Rate Fluctuations Research Articles

Iron (hydr)oxide minerals-microbe interaction associated retention capacity boost and reaction rate fluctuation for perfluorooctanoic acid in an in-situ iron-based and microbe-based sustained-release system

Iron (hydr)oxide minerals-microbe interaction associated retention capacity boost and reaction rate fluctuation for perfluorooctanoic acid in an in-situ iron-based and microbe-based sustained-release system

Effects of the intrayear fluctuation in serum albumin levels on the prognosis of patients on hemodialysis: a six-center, 3-year observational study in Japan

Abstract Background Malnutrition and hypoalbuminemia are prognostic factors for mortality in patients undergoing hemodialysis (HD). We hypothesized that the monthly variability in albumin levels was a stronger prognostic factor than its baseline level. Therefore, in this study, we aimed to investigate the association between the 3-year prognosis and 1-year fluctuations in serum albumin levels of patients on HD. Methods In this retrospective follow-up study, we enrolled patients on HD from six centers between January 2014 and December 2014. Serum albumin levels were obtained every month during this period. We calculated the fluctuation rate of serum albumin levels using the following equation: (highest value – lowest value of the year)/average value of albumin during the year. We divided the patients into two groups on the basis of the median fluctuation rate. All patients were followed up from January 2015 to January 2017. The primary outcome of this study was all-cause mortality, and the secondary outcome was the combined endpoint of mortality and major cardio-cerebrovascular adverse events (MACCEs). Results Overall, 621 patients on HD were included in this study. The median rate of fluctuation in albumin levels in all patients was 14.5%. Compared with patients in the low fluctuation (LF) group (< 14.5%) (n = 308), those in the high fluctuation (HF) group (≥ 14.5%) (n = 313) were significantly older (67 versus 65 years; p = 0.009). During a mean follow-up period of 31.0 ± 10.1 months, there were 121 (19.5%) and 191 (30.5%) cases of all-cause death and combined endpoint, respectively. Kaplan–Meier analysis results showed that the HF group had a significantly worse prognosis in terms of all-cause mortality (log-rank test, p = 0.005) and combined endpoints (log-rank test, p = 0.001) than the LF group. Among patients with low albumin levels (< 3.7 g/dL), multivariate analysis results demonstrated that HF was independently associated with an increased risk of all-cause mortality and composite endpoint (hazard ratio [HR]: 1.02, 95% confidence interval [CI] 1.00–1.04, p = 0.011; HR: 1.02, 95% CI 1.00–1.03, p = 0.002). Conclusion In patients on HD, high fluctuations in serum albumin levels were significantly associated with increased all-cause mortality risk. Thus, attention should be paid not only to the monthly albumin level but also to its fluctuations.

Longitudinal Patterns and Predictors of Cognitive Impairment Classification Stability.

Classifications such as Cognitive Impairment, No Dementia (CIND) are thought to represent the transitory, pre-clinical phase of dementia. However, increasing research demonstrates that CIND represents a nonlinear, unstable entity that does not always lead to imminent dementia. The present study utilizes a longitudinal repeated measures design to gain a thorough understanding of CIND classification stability patterns and identify predictors of future stability. The objectives were to i) explore patterns of longitudinal stability in cognitive status across multiple assessments and ii) investigate whether select baseline variables could predict 6-year CIND stability patterns. Participants (N = 259) included older adults (aged 65-90years) from Project MIND, a six-year longitudinal repeated measures design in which participants were classified as either normal cognition (NC) or CIND at each annual assessment. A latent transition analysis approach was adapted in order to identify and characterize transitions in CIND status across annual assessments. Participants were classified as either Stable NC, Stable CIND, Progressers, Reverters, or Fluctuaters. Multinomial logistic regression was employed to test whether baseline predictors were associated with cognitive status stability patterns. The sample demonstrated high rates of reversion and fluctuation in CIND status across annual assessments. Additionally, premorbid IQ and CIND severity (i.e., single vs. multi-domain impairment) at baseline were significantly associated with select stability outcomes. CIND status was unstable for several years following baseline assessment and cognitive reserve may delay or protect against demonstrable cognitive impairment. Further, consideration of cognitive impairment severity at the time of initial classification may improve CIND classifications.

A Three‐Phase Omnidirectional Wireless Charger Based on Segmented Arc‐Shaped Coupler With High Anti‐Rotation Offset Feature for AUVs

ABSTRACTWhen the autonomous underwater vehicle (AUV) is charged by wireless charging technology (WCT), the coupler will be misalignment due to the impact of marine environment factors, which can lead to the weak stability of the system output. Besides, the electromagnetic field generated by the coaxial coil is concentrated in the center of the AUV hull, and the strong electromagnetic field may interfere with the normal operation of the power electronic equipment inside the AUVs. To address the above problems, this paper proposes a novel coupler with high anti‐offset and suppression of the central magnetic field of the AUVs. The coupler is composed of a three‐phase segmented arc‐shaped transmitter coils and a cylindrical receiver coil. The coupler can implement the suppression of the AUV central magnetic field and the promotion of anti‐rotation offset feature under the omnidirectional uniform magnetic field control method. To better adapt the proposed coupler and meet the battery charging requirements, a three‐phase wireless charging topology with a relay is designed, which can acquire the smooth transition between the two charging modes without constructing the wireless communication between two sides and detecting the state of charge (SOC). Finally, to verify the feasibility of the proposed scheme, a 1‐kW AUV wireless charging prototype is built. The experimental results indicate that the maximum output power fluctuation rate of the system is 1.1% in the case of the full‐angle rotation offset.

Filtration Behaviour of Ostrea edulis: Diurnal Rhythmicity Influenced by Light Cycles, Body Size and Water Temperature

AbstractDespite the existing studies on oyster physiology, it is a concern that, by ignoring the diurnal rhythmicity of feeding activities, the current knowledge on oyster filtration might be unrepresentative of their real filtration capacity. In the present study, the diurnal and nocturnal fluctuations of Ostrea edulis clearance rate were investigated for the first time under laboratory conditions, also considering the combined effects of water temperature and oyster size. A positive correlation was found between the mean clearance rate (CRm) and body size for both length and wet weight, with an average of 0.5 L h−1 and 0.1 L h−1 of water filtered by large and small adult oysters respectively during the 24-h experiment. A positive significant correlation between mean clearance rate and water temperature was found only for large oysters, suggesting further studies utilising temperature ranges closer to O. edulis thermal optimum are required to clarify the influence of temperature on oyster filtration activities across different size classes. The results of this study also showed a discontinuous ingestion of food by O. edulis throughout 24-h intervals, with higher values of clearance rate observed during hours of darkness at most temperatures for both size classes. This suggests photoperiod may have a potential influence on O. edulis filtration. Providing a better understanding of O. edulis filtration behaviour, these findings have implications for ecological restoration, aquaculture, and comparative studies on oyster bioenergetics and physiology, with direct applications to the development of predictive models and the assessment of ecosystem services provided by O. edulis habitat.

Vibration characteristics of rolling bearing cage under speed variation conditions

Speed variation conditions will deteriorate the stress state of the rolling bearing internal components and aggravate the vibration of the cage, thereby affecting the service life and reliability of rolling bearings. In this paper, a nonlinear dynamic analysis model of the cylindrical roller bearing is established considering the rubbing effect and hydrodynamic contact between the cage and the guiding ring, as well as the sliding between the cage and other rolling elements. The vibration characteristics of the cage is discussed under the start-stop conditions and different fluctuations of rotation rate. The results show that the vibration of the cage mainly occurs at the middle and late stages of the acceleration process, and the impact mainly occurs at the middle stage of the deceleration process under the start-stop conditions. Moreover, the fluctuation of inner ring speed will enhance the unstable motion of the cage, among which the vibration and impact of the cage are most severe under the rectangular fluctuation of speed, followed by simple harmonic and triangular fluctuations. The findings can provide a theoretical guidance for improving the performance of rolling bearings and ensuring their safe and reliable operation.

Base Rates of Non‐Proficiency in Reading and Math: Implications for Universal Screening

ABSTRACTSeveral researchers have called for schools to interpret universal screening results using posterior probabilities. Following this recommendation could require schools to move away from direct‐route, single‐measure screening unless base rates of risk fall within a narrow range. In this descriptive study, we investigated two questions surrounding the feasibility of adopting a probability‐based approach in schools. First, how many districts had base rates of risk that would allow educators to classify all students using a single screener? Second, to what extent would yearly fluctuation in base rates require planned flexibility in screening procedures? We used public state test data to estimate base rates of risk for each district in Florida, Oregon, and Wisconsin across four school years. Districts' base rates of risk were rarely within the required range for a single screener to classify all students based on posterior probabilities. Many districts had base rates conducive to direct route screening in at least 1 year but very few had base rates in the required zone across the 4 years. Using posterior probabilities to make screening decisions may require more changes to existing practices than simply interpreting screening results as probabilities. Additional research to promote the use of this approach in schools is needed.

Safety and Efficacy of opioid-sparing Anesthesia Compared with Traditional opioid-anesthesia

Objectives: The rationale of adoption opioid sparing anesthesia (OSA) is to achieve perioperative analgesia with a minimal amount of opioid combined to non-opioid adjuvants during and after surgery, namely multimodal anesthesia. The OSA approach was originally developed to overcome the known complications of opioid-based anesthesia (OA) and the present scoping review (ScR) aims at providing the clinical evidence of safety and efficacy of OSA with respect to OA. Methods: This ScR is mainly focused on studies presenting evidence on the safety and efficacy of OSA versus OA. PubMed, EMBASE databases were utilized to find relevant studies. Search strategy included the following keywords: “opioid sparing anesthesia complications, opioid sparing anesthesia efficacy, opioid sparing anesthesia safety”. The findings from the 25 included studies were categorized into the following subsections: article characteristics, goals of the studies, OSA protocols, and surgical settings analyzed. Results: In the 25 reviewed studies, evidence related to the impact of OSA versus OA was considered. Intraoperative safety and efficacy endpoints include hemodynamic stability and anesthetic/analgesic requirements. Postoperative endpoints include early cognitive dysfunction, opioid-induced bowel disorder, the physical status of mothers and newborns after labor and emergency cesarean, systemic immune and inflammation modifications, postoperative recovery, in-hospital and long-term opioid requirement, early postoperative pain, chronic postsurgical pain. The studies reported a lower intraoperative mean arterial pressure and heart rate fluctuations when α2 agonists are adopted, while no differences were recorded for other complication rates. Analysis of OSA approaches for the postoperative conditions includes α2 agonists, NMDA receptor blocking agents, gabapentinoids, nefopam hydrocloride and locoregional anesthesia techniques with a positive impact on most of the endpoints considered. Discussion: The clinical implementation of OSA encompasses the perioperative use of non-opioid drugs and locoregional anesthesia techniques. The reviewed studies reported OSA as a feasible approach to reduce opioid-related complications with no impact on patient’s safety.

Incentive Determination for Demand Response Considering Internal Rate of Return

The rapid expansion of renewable energy sources has led to increased instability in the power grid of Jeju Island, leading to the implementation of the plus demand response (DR) system, which aims to boost electricity consumption during curtailment periods. However, the frequency of curtailment owing to the increased utilization of renewable energy is outpacing the implementation of plus DR, highlighting the need for additional resources, such as energy storage systems (ESS). High initial investment costs have been the primary hindrance to the adoption of ESS by DR-participating companies but have not been fully considered in earlier studies on DR incentive determination. Therefore, this study proposes an algorithm for calculating appropriate incentives for plus DR participation considering the investment costs required for ESS. Based on actual load data, incentives are determined using an iterative mixed-integer programming (MIP) optimization method that progressively adjusts the incentive level to address the overall nonlinearity arising from both the multiplication of variables and the nonlinear characteristics of the internal rate of return (IRR), ensuring that the target IRR is achieved. A case study on the impact of factors such as IRR, ESS costs, and fluctuations in electricity rates on incentive calculations demonstrated that plus DR incentives required to achieve IRR targets of 5%, 10%, and 15% have increased linearly from 142.2 KRW/kWh to 363.0 KRW/kWh, confirming that the appropriate incentive level can be effectively determined based on ESS investment costs and target IRR. This result could help promote ESS adoption among DR companies and plus DR participation, thereby enhancing power grid stability.

A Comparison of the Vasicek and Cox, Ingersoll, and Ross Interest Rate Models in Valuation of Insurance Assets, Liabilities and Surplus

Insurance Company’s cash flows are subjected to the risk of interest rate (C-3 risk). To curb the effect of this risk, Insurance companies normally adopts an interest period model that predicts the movement of the rates of interest. The most common models adopted by the Insurance Companies are the vasicek (1977) model and The Cox, Ingersoll and Ross (1985) Model. These two models are stochastic single period short-rate models; however, they exhibit different assumptions and because of this, the future values of insurance Assets and liabilities are likely to differ when these models are applied to estimate their values. Valuing of Insurance Assets and liabilities, especially in the Kenyan market is very challenging because of the tremendous fluctuations of interest rates as a result of gradual increments of the rate of inflation. In order for insurance companies to correctly value their insurance policies, they need to have a substantive Knowledge of their cash flows. The current valuation methods of insurance assets, liabilities and Surplus based on a stochastic interest rate models do not consider the possibility of occurrence of model risk, and therefore there is a possibility of either under estimating the future values of insurance assets and liabilities or over estimating. In this research paper, Geometric simulation was used to explore the effect of model risk By creating a comparison between The vacisek and the Cox, Ingersoll and Ross interest rate model. First, we evaluated the value of an insurance company’s assets and liabilities by assuming that the interest rate process is followed by the Cox, Ingersoll and Ross model and The vasicek (1977). Model risk arose by the different Values obtained for both the vacisek and the Cox, Ingersoll and Ross model. The results of the simulation showed that the cox, Ingersoll and Ross interest rate model provided a better fit of interest as compared to The Vasicek model.

The Impact of Economic Factors on Saudi Arabia’s Foreign Trade with BRICS Countries: A Gravity Model Approach

Our investigation, bolstered by the robust gravity trade model and panel data econometric technique, underscores the pivotal factors that influence trade interactions between Saudi Arabia and the BRICS nations—Brazil, Russia, India, China, and South Africa. The study, spanning from 1998 to 2023, delves into key economic metrics such as the gross domestic product, exchange rate fluctuations, inflationary trends, political conditions, and trade deals. We employ a range of econometric strategies, including pooled Ordinary Least Squares (OLS) and fixed effects models, to reveal that the GDP of BRICS states consistently and significantly impacts trade volumes. Specifically, a 1% increase in the GDP of partner countries correlates with a 0.37% rise in trade volume within the pooled OLS model. This effect amplifies to 1.43% when adjusting for temporal and country-specific factors in the fixed effects, underscoring the importance of accommodating unobserved heterogeneity, which refers to the unmeasured factors that can influence the relationship between GDP and trade volume. The political stability of BRICS nations mitigates transactional risks and promotes more stable trade relationships, thereby enhancing trade flows. Fluctuations in exchange rates exert positive and significant effects. This indicates that a more robust Saudi Riyal, an essential policy instrument, can enhance trade by increasing the competitiveness of Saudi exports. This study demonstrates that economic magnitude, political stability, and exchange rates affect Saudi Arabia’s trade with BRICS nations. These results bolster the Kingdom’s Vision 2030 objectives for economic diversification. This research advocates for stable political climates and strategic trade agreements to enhance trade relations. This study asserts that this approach will guarantee sustainable growth and diminish the Kingdom’s reliance on oil exports, instilling optimism in the Saudi economy.

Joinpoint analyses of rates on hospital-recorded deliberate self-harm: an update on Danish national trends.

Deliberate self-harm (DSH) is a public health concern and the high rates among adolescents and females warrant continuous monitoring. The aim of this study was to determine trends in DSH rates by gender and age in Denmark during 2000-2021 using joinpoint regression analysis. A cohort design was applied to national register data on all individuals aged 10 + years living in Denmark during 2000-2021. DSH episodes were identified in somatic and psychiatric hospital data. Sex- and age-specific incidence rates (IR) were calculated by calendar years. Using joinpoint regression analyses, segments of change and their annual percent change (APC) were identified. The highest DSH rates were observed for males and females aged 19-24 years with IRs of 146.8 (95% CI 142.9-150.7) and 378.6 (95% CI 372.1-385.0) per 100,000 person-years, respectively. Major changes in DSH rates were found for the youngest age groups. A step decrease was found for males aged 19-24 years (-18.4; 95% CI -31.9- -2.3; p = < 0.030) during 2012 to 2015. A significant decline was observed during 2012-2016 for females aged 19-24 years (-18.9; 95% CI -26.8 - -10.2; p = 0.001). Poisoning was the most frequently used method. Seemingly, the financial recession in 2008 did not affect Danish DSH rates. Significant declines were observed for females in the years where means restrictive measures had been installed; thus, supporting their potential effect. Fluctuations in DSH rates among adolescents and young adults in recent years underscore the importance of continued monitoring.

Exchange Rate Dynamics and Monetary Fundamentals: Evidence from South Asian Countries

This paper examined the role of monetary fundamentals in determining nominal exchange rate changes in South Asian countries. The Vector Autoregressive (VAR) technique and Autoregressive Distribution Lag (ARDL) were used. Results from the VAR indicate that the exchange rate responds to shock originating from differences in money supply, inflation differential, interest rate, and real income differential and are consistent with the short-run predictions of the monetary model of the exchange rate. The results show that inflation and interest rate differentials are responsible for the majority of changes in exchange rates in the short run. The conclusion from the result is that, particularly in the short run, monetary fundamentals are the primary causes of exchange rate fluctuations in South Asian countries.

The impact of dollar price fluctuations on the GDP of developing countries: Iraq as a model

The exchange rate is a tool of monetary policy, which is a matter of monetary policy, determined by the Central Bank of Iraq, as well as the subject of the exchange rate of complex topics, and the importance of this research lies in understanding the impact of dollar price fluctuations on the Iraqi economy, which contributes to enhancing knowledge about how external factors interact with local economic conditions, providing valuable recommendations for decision-makers to design effective strategies to deal with these fluctuations and achieve greater economic stability. The descriptive approach was used to collect and analyze economic data related to dollar price fluctuations and its impact on GDP, which helps to understand the relationships between these variables in Iraq during the period (2003-2024), the most important conclusions reached by the research that the general trend indicates sustainable growth in GDP, but economic challenges, such as exchange rate fluctuations and inflation, need to be effectively addressed. The government and central bank should promote economic stability through effective monetary policies that support growth and maintain exchange rate stability.

Enhancing energy security and efficiency through a regional integration policy: The case of the Southern Cone

This paper addresses the knowledge gap concerning foreign exchange risk in energy transactions within the Regional Initiative Energy Integration System of the Southern Cone Countries (SIESUR) of the Latin American region. Focusing on the cross-border electricity, it investigates the impact of exchange rate fluctuations on the transaction model in SIESUR: US dollar-denominated cross-border energy contracts with a time lag between invoicing and payment. The objective of this paper is to estimate foreign exchange risk exposure and propose mitigation solutions. Analyzing foreign exchange risk of energy trading among SIESUR member countries reveals substantial financial costs hindering electricity integration. Energy importing countries, facing greater exposure of their local currencies and weakened bargaining power, are particularly vulnerable. A Monte Carlo simulation model, using historical exchange rate data, highlights significant currency volatility, emphasizing the substantial foreign exchange risk exposure within SIESUR. Notably, cost overruns of energy imports due to foreign exchange risk exposure can reach 12.6% of transaction value. Through a global analysis, potential strategies for risk management are explored to foster electricity exchange expansion. Efforts to mitigate foreign exchange risk are crucial for advancing electricity integration within the SIESUR region. This study underscores policy implications for enhancing regional energy security and promoting sustainable development.

Comparative efficacy of ciprofol and propofol in reducing respiratory depression during ERCP anesthesia: a randomized controlled trial

BackgroundPropofol is one of the important drug causes of respiratory depression in endoscopic retrograde cholangiopancreatography (ERCP) anesthesia. This study aims to clarify whether Ciprofol in ERCP anesthesia reduces the respiratory depression rate.MethodsIn this randomized controlled trial performed at the Surgical Endoscopy Center, the First Hospital of Lanzhou University between Jun 01, 2022 and Feb 20, 2024, patients undergoing ERCP anesthesia were randomly assigned into ciprofol (study group) or propofol (control group). Primary outcomes included respiratory depression rate during anesthesia, and secondary outcomes included body movement and hypoxemia, awakening time, mean arterial pressure and heart rate changes at key points during surgery.Results20 of the 306 patients had respiratory depression (6.5%). The frequency of respiratory depression was 3.3% in the group C and 9.8% in the group P, with a difference of 6.5% between the two groups (P = 0.035). Ciprofol anesthesia decreased the hyoxemia, injection pain, and circulation and heart rate fluctuations. Multivariable logistic regression analyses showed that Propofol (OR 1.970; 95% CI, 1.121–3.461, P = 0.018), mallampati classification>II (OR 1.594; 95% CI, 1.129–2.249, P = 0.008), and fasting time>10.5 h (OR 3.184; 95% CI, 1.531–6.621, P = 0.002) were independent risk factors for incidence of respiratory depression in ERCP anesthesia.ConclusionsFor patients undergoing anesthesia for ERCP, Ciprofol, compared to Propofol, has been shown to effectively reduce the incidence of intraoperative respiratory depression, thereby enhancing the safety of the anesthesia process.Trial registrationThis study was registered in the Chinese Clinical Trial Registry on 15/01/2022 (ChiCTR2200055629).

The Impact of Exchange Rate Fluctuations on Nigeria Capital Market Performance

The Impact of Exchange Rate Fluctuations on Nigeria Capital Market Performance

Direct combustion noise: Nearfield and non-compactness influences on pressure–heat release coherence

There are several mechanisms through which turbulent flames produce sound. In low Mach number, unconfined flows, direct combustion noise – i.e., unsteady gas expansion generated by heat release fluctuations – is known to be a dominant contributor. This study is motivated by the fact that in the farfield, the coherence between spatially integrated heat release fluctuations from acoustically compact flames and direct combustion noise is unity. This suggests that the role of direct combustion noise relative to other sources can be ascertained from the value of the coherence. However, in practice it is difficult to fully satisfy the requirements to achieve a unity coherence, even in cases where direct combustion noise is the dominant noise source. This paper explores the contribution of noncompactness and nearfield effects on coherence. For the noncompactness part, while it is often the case that flames are small relative to a wavelength, they are never infinitesimally small. For the nearfield aspect, it is often not possible or practical to obtain farfield measurements, particularly in confined environments. This paper presents calculations that quantify how these noncompactness and nearfield effects influence coherence values. These calculations provide guidance on frequency ranges over which direct combustion noise will lead to near-unity coherence values, as well as required distances and optimal angles for acoustic instrumentation.Novelty and significance statementThis study presents a theoretical study on the coherence between heat release rate and acoustic pressure fluctuations, which has been mostly overlooked in prior literature. To the extent of the author’s knowledge, this is the first attempt that identify and investigate the inconsistencies between traditional theory and experimental literature on coherence. Results have implications for our previous understanding of the relationship between the heat release rate fluctuations and direct noise, aiding in future studies on combustion noise.

Effects of Interest Rate Change on Private Sector Investment, Evidence From Pakistan

This study examines the effects of lending rates, inflation, and exchange rate fluctuations on private sector credits (PSC) in Pakistan from 1961 to 2017. The analysis shows that lending rates have a minimal impact on PSC, with an insignificant relationship. However, inflation and exchange rates show significant negative effects, indicating that rising prices and currency depreciation reduce private sector borrowing by increasing costs and uncertainty. These findings suggest that while interest rate management remains important, policymakers should prioritize strategies for stabilizing inflation and exchange rates to support private sector investment. Consequently, fostering macroeconomic stability may mitigate the indirect effects of the crowding-out phenomenon, promoting a favorable investment environment conducive to private sector growth.

The Role of Foreign Exchange Auctions in Yemen in Influencing Exchange Rate Fluctuations with Reference to Its Impact on Inflation Rates

The Role of Foreign Exchange Auctions in Yemen in Influencing Exchange Rate Fluctuations with Reference to Its Impact on Inflation Rates