4653 research outputs found
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Fiscal Resilience or Vulnerability? Assessing Public Debt Sustainability in the Developing Countries During 1996-2020
No full textThe topic of public debt sustainability is very relevant in the present context when developing countries are experiencing a continuous rise in their public debt stocks with unprecedented pressures on their primary balances. In such context, we aim in this study to examine public debt sustainability in a large sample of developing countries, using panel fiscal reaction function and panel unit root analysis as well as time series unit root tests for each country over the period 1996-2020. To delve further into the issue, we bifurcate developing countries as lower-middle-income economies and upper-middle-income economies, respectively. Our empirical estimates from the standard regressions (OLS, Sys GMM, and instrumental variable regression) and panel quantile regressions indicate the sustainability of public debt in developing countries and the two subsamples: lower-middle-income economies and upper-middle-income economies over the period under examination. Our time series unit root tests (ADF and PP) show that developing countries are largely sustainable except for four countries: Pakistan, Sri Lanka, Sudan, and Uganda, implying that although the fiscal response is stronger to the rising public debt ratios in the majority of the developing countries, there are countries in need of fiscal tightening and required to enhance primary balances in order to put their public debt ratios on a sustainable path. We suggest that developing countries need to be prudent in their debt policies, even if their fiscal responses are sustainable, in order to be better prepared for future uncertainties or crises.Economic
Protecting IoT Servers Against Flood Attacks with the Quasi Deterministic Transmission Policy
No full textServers at Supply Chains and othet Cyber-physical systems that receive packets from IoT devices should meet the QoS needs of incoming packets, and protect the system from Cyberattacks. UDP Floods are often included in attacks to overwhelm Supply Chains and the IoT through congestion that paralyzes their ability for timely Attack Detection and Mitigation. Thus this paper proposes an architecture that protects a connected Server using a Smart Quasi-Deterministic Transmission Policy Forwarder at its input. This Forwarder shapes the incoming traffic, sends it to the Server without increasing the overall packet delay, and avoids Server congestion. The relevant theoretical background is reviewed, and measurements during a UDP Flood Attack are provided to compare the Server performance, with and without the Forwarder. It is seen that during a UDP Flood Attack, the Forwarder protects the Server from congestion, allowing it to effectively identify Attack Packets. Congestion at the Forwarder is rapidly eliminated with drop commands generated by the Forwarder, or sent by the Server to the Forwarder.Computer Science, Artificial Intelligence || Computer Science, Information Systems || Computer Science, Theory & Methods || Telecommunication
Proteomic profiling of an extreme halophyte Schrenkiella parvula with accelerated root elongation under mild salt stress.
No full textIncreased salinity in soil is one of the impacts of climate change and a major problem for crop cultivation. Halophytes have the ability to survive in hypersaline environments, and investigating their adaptation mechanisms is effective in imparting salt tolerance to plants. Recently, we discovered a strategy by the extreme halophyte Schrenkiella parvula to promote primary root elongation, a morpho-physiological response that may be given to have access to groundwater sources, while reducing meristem DNA replication, root hair development, and biomass at moderate salinities around 100 mM NaCl. However, when NaCl concentration exceeds 200 mM, seedling root elongation is inhibited, and seedlings change to respond to severe stress induced by salinity. To understand the interesting physiological and molecular mechanisms underlying primary root elongation at moderate salinity, we performed a proteomic analysis using two-dimensional gel electrophoresis and MALDI-TOF MS. Ultimately, a total of 300 different proteins were identified, of which 20 showed significant increases and 25 showed significant decreases at 100 mM NaCl. Among the increased proteins, proteins responding to abiotic stress such as glutathione transferases were found, and among the decreased proteins, proteins involved in glycolysis, purine nucleotide synthesis, and protein synthesis were found. Accumulation levels of proline, an osmotic regulator that inhibits root growth, were lower in S. parvula than in A. thaliana. On the other hand, interestingly, the expression levels of fructose-bisphosphate aldolase, sucrose phosphatase, and alpha-subunit of acetyl-CoA carboxylase increased. In addition, increases in P5CDH, an enzyme in the proline catabolism process, and decreases in GLN and GDH in glutamate synthesis in S. parvula suggest that these may lead to a fine-tuning of proline content. For annexins, a family of calcium -binding and membrane -bound proteins that regulate plant tolerance, moderate salt treatment showed a significant decrease in SpANN7, a non -significant downtrend for SpANN2, but no change for SpANN1. These findings suggest that the 100 mM NaCl does not create a serious stress for S. parvula. We also performed gene expression analysis of these altered proteins between S. parvula and A. thaliana. Taken together, in S. parvula roots, 100 mM NaCl partially induced the redox homeostasis system, stress response, and proline-mediated osmoregulation, moderately suppressing carbon metabolism, nucleotide, and protein synthesis to accelerate primary root elongation.Plant Science
Performance evaluation of machine learning algorithms for the prediction of particle Froude number (Frn) using hyper-parameter optimizations techniques
No full textThe sewer system is a critical component of urban infrastructure, responsible for transporting wastewater and stormwater away from populated areas. Proper design and management of sewer systems are essential to prevent flooding, reduce environmental pollution, and ensure public health and safety. One crucial parameter in sewer system design and management is the particle Froude number (F-rn). The goal of this study is to develop a predictive algorithm that takes into account the relevant input parameters, such as volumetric sediment concentration (C-v), dimensionless grain size of particles (D-gr), the ratio of sediment median size to the hydraulic radius (d/R), pipe friction factor (lambda) to accurately predict the F-rn using an ablation study for the condition of non-deposition with clean bed data. The proposed approach is based on hyper-parameter optimization techniques, i.e., Babysitting method (BSM), GridSearchCV (GS), random search (RS), Bayesian optimization with Gaussian process (BO-GP), Bayesian optimization with tree-structures Parzen estimator (BO-TPE), and particle swarm optimization (PSO), which are applied to the four machine learning algorithms such as random forest (RF), gradient boosting (GB), K-nearest neighbor (KNN), and support vector regression (SVR). The proposed algorithms are compared with the existing algorithms in terms of coefficient of determination (R-2), root mean square error-observations standard deviation ratio (RSR), and normalized mean absolute error (NMAE) to assess the performance of the proposed algorithms. The results show that the proposed algorithms yield superior outcomes across all performance metrics. Among the proposed algorithms, GB+PSO predicted F-rn with significant accuracy and has the highest prediction accuracy (R-2 = 0.996, RSR = 0.068, and NMAE = 0.009, respectively), followed by RF+BO-GP, SVR+RS, and KNN+PSO. We have provided a comparison with the existing state-of-the-art methods and beat them. We evaluate these proposed algorithms against several widely recognized empirical equations found in the existing literature.Computer Science, Artificial Intelligence || Engineering, Electrical & Electronic || Operations Research & Management Scienc
Interrelationship between environmental degradation, geopolitical risk, crude oil prices, and green bonds: Evidence from the globe by sectoral analysis
No full textBy considering the motion of the world is our home, this study investigates the interrelationship between environmental degradation, geopolitical risk, crude oil prices, and green bonds across the globe. So, the research considers the probable differences between the sectors by making a detailed analysis of CO 2 emissions across sectors, applies the novel WLMC method, and uses daily data from 2nd January 2020 through 30th November 2023 for a time and frequency -based empirical analysis. The outcomes present that (i) the geopolitical risk is the most important variable on CO 2 emissions between 2020/1 and 2021/11 followed by Brent oil prices for the period 2021/12-2023/10 || (ii) green bonds are highly effective on CO 2 emissions only around 2023/11 || (iii) the impacts of the variables are quite weaker (stronger) at lower (higher) frequencies || (iv) the impacts of the variables are the same at aggregated and disaggregated levels || (v) the impact of the variables on CO 2 emissions change based on times and frequencies. Thus, the outcomes demonstrate new insights for differentiating impacts across times and frequencies, whereas the direction of the impacts is the same across aggregated and disaggregated levels. (c) 2024 International Association for Gondwana Research. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.Geosciences, Multidisciplinar
Conservatism Negatively Predicts Creativity: A Study Across 28 Countries
No full textPrevious studies have found a negative relationship between creativity and conservatism. However, as these studies were mostly conducted on samples of homogeneous nationality, the generalizability of the effect across different cultures is unknown. We addressed this gap by conducting a study in 28 countries. Based on the notion that attitudes can be shaped by both environmental and ecological factors, we hypothesized that parasite stress can also affect creativity and thus, its potential effects should be controlled for. The results of multilevel analyses showed that, as expected, conservatism was a significant predictor of lower creativity, adjusting for economic status, age, sex, education level, subjective susceptibility to disease, and country-level parasite stress. In addition, most of the variability in creativity was due to individual rather than country-level variance. Our study provides evidence for a weak but significant negative link between conservatism and creativity at the individual level (beta = -0.08, p < .001) and no such effect when country-level conservatism was considered. We present our hypotheses considering previous findings on the behavioral immune system in humans.Psychology, Socia
COVID-19 and Social Distancing: A Cross-Cultural Study of Interpersonal Distance Preferences and Touch Behaviors Before and During the Pandemic
No full textThe COVID-19 pandemic has led to the introduction of unprecedented safety measures, one of them being physical distancing recommendations. Here, we assessed whether the pandemic has led to long-term effects on two important physical distancing aspects, namely interpersonal distance preferences and interpersonal touch behaviors. We analyzed nearly 14,000 individual cases from two large, cross-cultural surveys - the first conducted 2 years prior to the pandemic and the second during a relatively stable period of a decreased infection rate in May-June 2021. Preferred interpersonal distances increased by 54% globally during the COVID-19 pandemic. This increase was observable across all types of relationships, all countries, and was more pronounced in individuals with higher self-reported vulnerability to diseases. Unexpectedly, participants reported a higher incidence of interpersonal touch behaviors during than before the pandemic. We discuss our results in the context of prosocial and self-protection motivations that potentially promote different social behaviors.Social Sciences, Interdisciplinar
Pop-ups can be ugly: temporary architecture built with emotions
No full textPop-ups are temporary installations, constructions, or structures that suddenly appear in urban contexts to draw attention for commercial, artistic, or social purposes. Temporary pavilions, whose existence is bound to their capability to engage with unknown citizens or passers-by and offer them a spatial experience, are also identified as pop-ups. However, what are the features that make a temporary structure a pop-up? What architectural elements do designers outsource when conceiving and materialising pop-up architecture? At what point does a pop-up become something else? This paper aims to answer these questions by providing insights into design explorations that extend the meaning of pop-ups and enquiring, through a survey and interviews, the boundaries of what can be understood as pop-up architecture. Collective definitions address the fundamental role of human emotions in the conceptualisation and materialisation of these temporary structures, suggesting the secondary role of aesthetics when engaging with users.Architectur
Exergy-based techno-economic and environmental assessments of a proposed integrated solar powered electricity generation system along with novel prioritization method and performance indices
No full textThis study focused on the two important gaps in the literature. The first is solar energy- powered electricity generation in a more economical way via the integration of flat plate solar collector (FPSC), an Organic Rankine Cycle (ORC), and an absorptional heat transformer (AHT) system. Another gap is advanced exergy analysis of the AHT cycle/ORC process based on renewable energy integration to reveal clues for improving the system. To close these gaps, a novel system including a lithium bromide AHT cycle-ORC with a FPSC system application was proposed in this study. In this proposed system, the temperature of the heat source for the ORC system was upgraded via an integration of the AHT and FPSC cycles. The main components of the AHT cycle are the condenser (ABScon), refrigerant cycle pump (P1), evaporator (EV), absorber (ABS), solution heat exchanger (SHX), absorbent cycle pump (P2), expansion valve (V), generator (Gen), ORC turbine (ORCT) and ORC condenser (ORCcon). To demonstrate the electricity production from solar energy in a more economical way thanks to the proposed system, a comparison was made with similar-scaled existing solar power plants. The results supported the main purpose of this study. The annual electricity production with the proposed system was calculated as 2601 MWh, with initial investment cost and payback period values of US$3.924 million and 4.531 years, respectively. The conventional and advanced exergy, exergoeconomic, environmental impact, and sustainability analyzes were also performed. Based on these, the novel performance parameters and prioritization method were proposed to assess the improvement potential of the system. The results indicated that SHX and FPSC had the highest exergy destruction rates (EDRs) of 23.711% and 21.849% over 5853.89 kW due to the stronger thermal and chemical reactions. Similarly, Gen, FPSC, and SHX had the highest ED cost rates (CRs) of 67.59%, 59.09%, and, 47.98%, respectively. Gen, V, and ORCcon were higher contributors to the exergy destruction rates of almost all the components. However, these showed an adverse manner for irreversibility activities. So, the temperatures of Gen and ORCcon should be optimized carefully. ABScon, P2, P1, ABS, Gen, ORCT, and ORCcon had high development priority to improve the whole system.Engineering, Environmental || Engineering, Chemica
Mathematical modelling and performance analysis of a novel auto-cascade refrigeration cycle for ultra-low temperature applications
No full textThe main objective of this study is to assess both energetically and exergetically the performance of a novel auto-cascade refrigeration (NACR) cycle enhanced by an internal heat exchanger using R290/R170. In contrast to the ACR cycle with a -60 degrees C evaporation temperature, the NACR cycle displays a COP increase of 140.78% and a 148.67% improvement in exergy efficiency. Additionally, there is a notable decrease of 13.77% in compressor discharge temperature. For an evaporation temperature of -55 degrees C, the NACR cycle achieves a COP of 0.403 and an exergy efficiency of 14.61%, with the compressor discharge temperature registering at 126.60 degrees C.Thermodynamics || Energy & Fuel