Effect Of Fluctuations Research Articles

Local and Nonlocal Electronic Correlations at the Metal-Insulator Transition in the Two-Dimensional Hubbard Model.

Elucidating the physics of the single-orbital Hubbard model in its intermediate-coupling regime is a key missing ingredient to our understanding of metal-insulator transitions in real materials. Using recent nonperturbative many-body techniques that are able to interpolate between the spin-fluctuation-dominated Slater regime at weak coupling and the Mott insulator at strong coupling, we obtain the momentum-resolved spectral function in the intermediate regime and disentangle the effects of antiferromagnetic fluctuations and local electronic correlations in the formation of an insulating state. This allows us to identify the Slater and Heisenberg regimes in the phase diagram, which are separated by a crossover region of competing spatial and local electronic correlations. We identify the crossover regime by investigating the behavior of the local magnetic moment, shedding light on the formation of the insulating state at intermediate couplings.

Marginal Fermi liquid behavior at the onset of 2kF density wave order in two-dimensional metals with flat hot spots

We analyze quantum fluctuation effects at the onset of incommensurate 2kF charge- or spin-density-wave order in two-dimensional metals for a model in which the ordering wave vector Q connects a single pair of hot spots on the Fermi surface with a vanishing Fermi surface curvature. The tangential momentum dependence of the bare dispersion near the hot spots is proportional to |kt|α with α>2. We first compute the order parameter susceptibility and the fermion self-energy in a random phase approximation (RPA). Logarithmic divergences are subsequently treated by a renormalization-group analysis. The coupling between the order parameter fluctuations and the fermions vanishes logarithmically in the low-energy limit. As a consequence, the logarithmic divergences found in the RPA do not sum up to anomalous power laws. Instead, only logarithmic corrections to Fermi liquid behavior are obtained. In particular, the quasiparticle weight and the Fermi velocity vanish logarithmically at the hot spots. Published by the American Physical Society 2024

Eco-fertility: examining the climate change-total fertility rate nexus in the context of sustainable developmental goals in a systematic review approach

Abstract Sustainable Development Goals (SDGs) are paramount as the global community confronts the ramifications of climate alterations, especially its implications on population dynamics. Initial studies suggest an intricate relationship between environmental determinants and reproductive choices. This systematic review elucidates the complex interplay between climate-related challenges and observed global fertility rate variations. A comprehensive search and analysis of literature published in the last 10 years (2013–2023), available in the PubMed database, delineates the relationship between environmental changes and fertility patterns in both human and animal populations. The review highlighted significant effects of climatic fluctuations on reproductive health, manifested as either adaptive or maladaptive responses to environmental stressors. This relationship not only influences population trajectories but may also have complications for the SDGs, specifically those pertaining to health, well-being, and gender equality. The study emphasizes the importance of intertwining demographic insights with ecological considerations. A deeper understanding of the nexus between climate and fertility can augment strategies aimed at global sustainability. The synthesized evidence underscores the urgency for further research, which seeks to seamlessly incorporate eco-fertility perspectives into wider climate and sustainability discussions.

Phenotypic plasticity and the effects of thermal fluctuations on specialists and generalists.

Classical theories predict that relatively constant environments should generally favour specialists, while fluctuating environments should be selected for generalists. However, theoretical and empirical results have pointed out that generalist organisms might, on the contrary, perform poorly under fluctuations. In particular, if generalism is underlaid by phenotypic plasticity, performance of generalists should be modulated by the temporal characteristics of environmental fluctuations. Here, we used experiments in microcosms of Tetrahymena thermophila ciliates and a mathematical model to test whether the period or autocorrelation of thermal fluctuations mediate links between the level of generalism and the performance of organisms under fluctuations. In the experiment, thermal fluctuations consistently impeded performance compared with constant conditions. However, the intensity of this effect depended on the level of generalism: while the more specialist strains performed better under fast or negatively autocorrelated fluctuations, plastic generalists performed better under slow or positively autocorrelated fluctuations. Our model suggests that these effects of fluctuations on organisms' performance may result from a time delay in the expression of plasticity, restricting its benefits to slow enough fluctuations. This study points out the need to further investigate the temporal dynamics of phenotypic plasticity to better predict its fitness consequences under environmental fluctuations.

Statistical investigation on the relationship between climate change, food availability, agricultural productivity, and economic expansion

This study examined the connections between Benin's economic expansion, food production, agricultural productivity, and climate change. Using yearly statistics between 1961 and 2021, and R software version 4.2.2, we aim to: (1) Analyze how agricultural added value affects economic expansion; (2) analyze the effects of food production and temperature lagged values on economic growth; (3) investigate the different causality relationships between food production, temperature variation, agricultural added value and economic growth. To achieve these goals, statistical and econometric techniques such as Autoregressive Distributed Lags (ARDL) and the Toda-Yamamoto Granger causality framework were employed. The ARDL model verifies that there is a positive correlation between economic growth and the added value of agriculture based on empirical data. In addition, the Vector Autoregressive (VAR) model highlights the favorable impact of lagged food production values and the adverse effect of temperature fluctuations on economic growth. Granger causality analysis, employing the Toda-Yamamoto approach, unveils unidirectional links between food production and economic growth, as well as between temperature variation and agricultural added value. Interestingly, the study comes to the conclusion that there are no direct causal links between economic expansion and agricultural growth or between economic growth and temperature variance. Notably, bidirectional causality is established between livestock production and both economic growth and agricultural added value. These insights have significant implications for understanding climate change impacts on agriculture and suggest the need for adapted strategies to mitigate climate effects. Future research could focus on evaluating existing policies, exploring social and economic impacts, investigating market dynamics, and utilizing integrated assessment modeling to inform decision-making and foster sustainable economic growth in Benin's agricultural sector.

Effects of temperature fluctuations on the quality and characteristic volatile compounds of large yellow croaker ( Pseudosciaena crocea) during cold chain logistics

Effects of temperature fluctuations on the quality and characteristic volatile compounds of large yellow croaker ( <i>Pseudosciaena crocea</i>) during cold chain logistics

Linearity and intermodulation distortion analysis of single and dual metal gate junctionless transistor

Linearity and intermodulation distortion are very crucial parameters for RFICs design. Therefore, in this work, a detailed comparative analysis on linearity and intermodulation distortion of single metal (SMG) and double metal (DMG) double gate junction less transistor (JLT) is done using TCAD silvaco suite. Furthermore, the effects of temperature fluctuation, gate length variation, and gate material engineering on the linearity performance of both devices are also studied. A few significant figures of merit, including Voltage Intercept Point 2 (VIP2), Voltage Intercept Point 3 (VIP3), Third Order Intercept Power (IIP3), 1 dB Compression Point (P1dB), Third Order Intermodulation Distortion (IMD3), and the transconductance derivative parameters First Order Transconductance (gm1), Second Order Transconductance (gm2), and Third Order Transconductance (gm3) are used to assess the device linearity and intermodulation distortion of SMG and DMG JLT's. The findings show that higher VIP2, VIP3, IIP3, 1-dB compression point and lower gm3, IMD3 values are obtained for the SMG JLT device when compared to its counterpart DMG JLT. SMG JLT, which assures strong linearity and low distortion.

Retrospective Evaluation of the Effects of Local Anesthesia Before Tooth Extraction Procedures under General Anesthesia on Physiologic Parameters and Postoperative Bleeding in Children

Background: Studies have been conducted to evaluate changes in hemodynamics, postoperative bleeding, and pain in pediatric dental patients receiving general anesthesia (GA). However, a limited number of studies have evaluated the effects of local anesthetics (LA) on tooth extraction procedures during GA. There is no consensus in the literature regarding LA application in the perioperative period for dental treatments performed within the scope of GA. Aim: This study aimed to determine the retrospective physiologic effects of fluctuations in vital signs and postoperative bleeding in children who did or did not receive LA for tooth extraction under GA. Methods: A retrospective evaluation of 77 patients aged 5.16 ± 1.85 years who had the extraction of primary posterior teeth with or without LA under GA were reviewed in the post-anaesthesia care unit (PACU) for postoperative bleeding and the effects of intraoperative LA on fluctuations in postoperative parameters such as mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2), respiratory rate (RR), and the end-tidal carbon dioxide (EtCO2). These were compiled from the patient records of the procedures. Results: Significant differences between the baseline and peak MAP (P &lt; 0.001), HR (P = 0.011), and EtCO2 (P = 0.002) were noted in children without LA compared to those who had LA. In addition, substantial variations were observed between the baseline and peak values for MAP (P &lt; 0.001) and HR (P = 0.037) in children who had tooth extraction in the mandibular region. Statistically significant differences were noted between the baseline and peak values for patients who did not receive LA before the extraction of the first primary molar in terms of MAP (P &lt; 0.02) and EtCO2 (P = 0.032). Similarly, significant differences in MAP (P &lt; 0.02) and EtCO2 (P = 0.034) were noted in the extraction of the second primary molar. In addition, there was a significant difference in bleeding based on the number of tooth extractions in those who did not receive LA (P = 0.020). Conclusion: This study showed that in children who underwent tooth extraction under GA, additional LA application minimized changes in HR, MAP, and EtCO2, whereas a lack of LA application produced significant fluctuations from baseline to peak values of HR, MAP, and EtCO2. In addition, LA application reduced postoperative bleeding.

The Effect of Food Price Fluctuations on the Poverty Rate in Aceh Province, Indonesia

The government continues to address poverty through various policies including food security initiatives, but the poverty rate in Aceh is still relatively high when compared to other provinces in Indonesia. Given this urgency, this study aims to estimate the short-term and long-term effects of food prices on poverty rates in Aceh using an Error Correction Model (ECM) supplemented by observations of long-term equilibrium or cointegration relationships. The secondary data used is the period 2014Q1 - 2022Q4. The estimation results show that in the short and long run, food prices have a significant effect and are positively related to the poverty rate in Aceh. The imbalance between the actual poverty rate and the desired poverty rate will be adjusted over 3.32 quarters. Therefore, the Aceh Government's measures and policies in alleviating poverty need to be revisited by consistently improving the quality of human resources, quantity, and sustainability of agricultural production.

Efficient and accurate uncertainty quantification in engineering simulations using time-separated stochastic mechanics

A robust method for uncertainty quantification is undeniably leading to a greater certainty in simulation results and more sustainable designs. The inherent uncertainties of the world around us render everything stochastic, from material parameters, over geometries, up to forces. Consequently, the results of engineering simulations should reflect this randomness. Many methods have been developed for uncertainty quantification for linear elastic material behavior. However, real-life structure often exhibit inelastic material behavior such as visco-plasticity. Inelastic material behavior is described by additional internal variables with accompanying differential equations. This increases the complexity for the computation of stochastic quantities, e.g., expectation and standard deviation, drastically. The time-separated stochastic mechanics is a novel method for the uncertainty quantification of inelastic materials. It is based on a separation of all fields into a sum of products of time-dependent but deterministic and stochastic but time-independent terms. Only a low number of deterministic finite element simulations are then required to track the effect of (in)homogeneous material fluctuations on stress and internal variables. Despite the low computational effort the results are often indistinguishable from reference Monte Carlo simulations for a variety of boundary conditions and loading scenarios.

Effect of thermal fluctuations on mold coating delamination during continuous casting of high-alloy (Mn, Al) steel

During the continuous casting of high-alloy (Mn, Al) steels, mold coating delamination occurs specifically at the narrow face (NF) mold corner immediately below the meniscus, different from where mold surface problems are generally known to occur. Most mechanical analyses have been performed assuming negligible thermal fluctuations and steady state interfacial heat fluxes. However, high-alloy steels exhibit larger thermal fluctuations than general steels during continuous casting, attributable to the reaction between the high-alloy steels and mold flux. Therefore, in this study, thermo-mechanical analyses are performed under both steady and fluctuating interfacial heat fluxes to compare the effects of thermal fluctuations on the continuous casting mold, with the results indicating that monotonic stresses are generated under steady interfacial heat fluxes at the corner of the NF mold, whereas cyclic stresses are induced by thermal fluctuations under fluctuating interfacial heat fluxes. Accordingly, the cyclic stresses at the corner of the NF mold, induced by thermal fluctuations, are determined as the major cause of mold coating delamination. These results can be applied to develop methods to reduce mold coating delamination, prevent the degradation of strand quality, and improve mold life.

An Investigation into How Fluctuations in Global Crude Oil Prices Impact Tadawul All-Shares Index (TASI) (January 1995-December 2017)

This paper investigates the effect of fluctuations in the global oil market on the movement of the TADAWUL All Shares Index, TASI, by using monthly data for the period between January 1995 and December 2017. To capture the impact of the global oil market, this paper uses the two main benchmarks in the global oil market, West Texas Intermediate (WTI), and Brent Crude oil. As the stock market is known to be stochastic, a set of secondary explanatory variables is added to this research. It consists of the following: inflation rates, short-term interest rates, gold spot prices, level of imports, level of funds invested in private securities by the private sector, and proxy for global equity markets, FTSE 100. The FTSE 100 has a significant impact on the TASI index, the coefficient is close to 1. The significant impact of the FTSE 100 on the TASI index could signal the existence of many dual investors in both indices. The results show that all variables have an impact on the TASI index at a statistically significant level. Despite the positive impact of spot prices on both benchmarks, the futures strip curve for both benchmarks are inversely related to the predicted variable. Also, the TAIS index is more exposed to changes in the WTI than changes in Brent Crude. It is clearly shown in the coefficient values, .359 and .302, for WTI and Brent Crude respectively. Moreover, over the sample period there is an increase in the level of the explained variation in the TASI index by the explanatory variable. This would indicate that TASI has become a less speculative and more sophisticated market. Finally, as this paper provides evidence for the impact of the global equity market on TASI, it would open a window for future research to examine the impact of other international equity markets on TASI.

The effects of policy fluctuations on energy indices in Iran's agriculture sector

The effects of policy fluctuations on energy indices in Iran's agriculture sector

Dynamic changes in evapotranspiration, canopy photosynthesis and expansive growth in open field under rapid fluctuating radiation

In open fields, plants experience dynamic changes in environment, particularly radiation, temperature, wind, and humidity but their short-term responses have not been adequately characterized under natural conditions. In this study, we assessed causal effects of rapid radiation fluctuation on seven plant parameters in open fields of cotton and sweet corn canopies. The parameters are evapotranspiration (ET), canopy photosynthesis indicated by CO2 flux from air to canopy (FCO2), sensible heat energy flux (H), canopy conductance for water vapor (gcw), canopy surface temperature (Ts), shoot and leaf elongation rate, and stem diameter change. The energy and CO2 fluxes were measured with Bowen ratio/energy balance/CO2 gradient (BREB+) technique, using averaging time of 5 min. Shoot + leaf elongation and stem diameter change were monitored with position transducers using averaging time of 1 min. All parameters were all found to respond to change in radiation and transpiration within minutes or sooner. While radiation effects on canopy gas exchanges are expected, illuminating are the indirect but immediate effects on shoot + leaf growth and stem diameter change through radiation effects on transpiration and plant water status. A novel finding is that gcw also responded within minutes or sooner to radiation fluctuations and that FCO2 was related almost linearly to gcw. Results are discussed in terms of soil-plant-atmosphere continuum, and interpreted in terms of dynamic interactions between transpiration and plant water status. The clear inverse relationship between ET and elongation rate or stem diameter changes provides additional evidence supporting the validity of 5-min averaging for the BREB + technique.

Effect of thermal fluctuations on spectra and predictability in compressible decaying isotropic turbulence

This study investigates the impact of molecular thermal fluctuations on compressible decaying isotropic turbulence using the unified stochastic particle (USP) method, encompassing both two-dimensional (2-D) and three-dimensional (3-D) scenarios. The findings reveal that the turbulent spectra of velocity and thermodynamic variables follow the wavenumber (k) scaling law of ${k}^{(d-1)}$ for different spatial dimensions $d$ within the high wavenumber range, indicating the impact of thermal fluctuations on small-scale turbulent statistics. With the application of Helmholtz decomposition, it is found that the thermal fluctuation spectra of solenoidal and compressible velocity components ( ${\boldsymbol {u}}_{s}$ and ${\boldsymbol {u}}_{c}$ ) follow an energy ratio of 1 : 1 for 2-D cases, while the ratio changes to 2 : 1 for 3-D cases. Comparisons between 3-D turbulent spectra obtained through USP simulations and direct numerical simulations of the Navier–Stokes equations demonstrate that thermal fluctuations dominate the spectra at length scales comparable to the Kolmogorov length scale. Additionally, the effect of thermal fluctuations on the spectrum of ${\boldsymbol {u}}_{c}$ is significantly influenced by variations in the turbulent Mach number. We further study the impact of thermal fluctuations on the predictability of turbulence. With initial differences caused by thermal fluctuations, different flow realizations display significant disparities in velocity and thermodynamic fields at larger scales after a certain period of time, which can be characterized by ‘inverse error cascades’. Moreover, the results suggest a strong correlation between the predictabilities of thermodynamic fields and the predictability of ${\boldsymbol {u}}_{c}$ .

Superfluid-supersolid phase transition of elongated dipolar Bose-Einstein condensates at finite temperatures

We analyze the finite-temperature phase diagram of a dipolar Bose-Einstein condensate confined in a tubular geometry. The effect of thermal fluctuations is accounted for by means of Bogoliubov theory employing the local density approximation. In the considered geometry, the superfluid-supersolid phase transition can be of first and second order. We discuss how the corresponding transition point is affected by the finite temperature of the system. Published by the American Physical Society 2024

Symmetry breaking charge transfer and control of the transition dipole moment in excited octupolar molecules.

The structure of the energy levels of excited symmetric donor-acceptor octupolar molecules suggests a completely symmetric state and a degenerate doublet. For most molecules, the doublet is the first excited state, which is called the normal level order, but there are molecules with the reverse level order. Symmetry breaking charge transfer (SBCT) and its effect on the transient dipole moment in these structures are studied. It has been established that for reverse level order, SBCT is possible only if the reorganization energy exceeds a certain threshold, whereas for the normal level order, there is no such threshold. The lowest completely symmetric excited state is shown to become bright after SBCT. The dependence of the fluorescence transition dipole moment on the SBCT extent is calculated. It was established that the direction and magnitude of the transition dipole moment change similarly to the change in the dipole moment for the reverse level order, whereas for the normal level order, the changes are opposite. The effect of solvent thermal fluctuations on the transition dipole moment is simulated and discussed. A way for controlling the direction of the transition dipole moment by an external electric field is suggested.

The Effects of Exchange Rate Fluctuation on Bangladeshi Exports: An ARDL Bound Testing Technique

The Effects of Exchange Rate Fluctuation on Bangladeshi Exports: An ARDL Bound Testing Technique

The Impact of Energy-Related Uncertainty on Corporate Investment Decisions in China

This study investigates the impact of the Energy-related Uncertainty Index (EUI) on corporate investment among Chinese non-financial listed companies, focusing on two aspects: the effect of EUI fluctuations on investment behavior, and its differential impact on energy versus non-energy sectors. Utilizing a dataset of 2487 firms from 2007 to 2022, encompassing 22,346 firm-year observations, our analysis reveals that a 1% increase in the EUI leads to a 0.045% decrease in overall corporate investment. Notably, this effect is more pronounced in energy-related firms, where a 1% increase in EUI leads to a 0.057% reduction in investment. In comparison, non-energy-related firms exhibit a milder response, with a 1% increase in EUI resulting in a 0.026% decrease in investment. Given the average annual change in EUI over the sample period [2007–2022] of 27.710%, a 0.045% decrease in investment implies a substantial 1.246% per annum change in investment. This highlights the economically significant impact of EUI fluctuations on corporate investment decisions, particularly during periods of heightened uncertainty. These findings, validated through alternative EUI measures and investment metrics, provide crucial insights for understanding investment behavior under energy uncertainty. Conclusively, our study contributes to the literature by highlighting how energy uncertainty uniquely impacts corporate investment, taking into account the specific financial and operational conditions within different sectors. The findings highlight the importance of incorporating energy policy considerations into corporate strategic planning, particularly for energy-intensive industries within transitional economies like China.

Factors affecting the production of sugarcane yield and sucrose accumulation: suggested potential biological solutions.

Environmental stresses are the main constraints on agricultural productivity and food security worldwide. This issue is worsened by abrupt and severe changes in global climate. The formation of sugarcane yield and the accumulation of sucrose are significantly influenced by biotic and abiotic stresses. Understanding the biochemical, physiological, and environmental phenomena associated with these stresses is essential to increase crop production. This review explores the effect of environmental factors on sucrose content and sugarcane yield and highlights the negative effects of insufficient water supply, temperature fluctuations, insect pests, and diseases. This article also explains the mechanism of reactive oxygen species (ROS), the role of different metabolites under environmental stresses, and highlights the function of environmental stress-related resistance genes in sugarcane. This review further discusses sugarcane crop improvement approaches, with a focus on endophytic mechanism and consortium endophyte application in sugarcane plants. Endophytes are vital in plant defense; they produce bioactive molecules that act as biocontrol agents to enhance plant immune systems and modify environmental responses through interaction with plants. This review provides an overview of internal mechanisms to enhance sugarcane plant growth and environmental resistance and offers new ideas for improving sugarcane plant fitness and crop productivity.