841 research outputs found

    Learning from one another: the U.S. and European banking experience

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    Banking structure ; European Economic Community

    Control-oriented modelling and simulation of a variable-frequency efficiency-optimized flyback converter

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    Driven by the requirement for a fairly accurate and fast simulation of a variable frequency digital controlled flyback converter, this paper develops a control-oriented mathematical model, which retains the essential dynamic characteristics of the real system, but offers significant computational complexity reduction compared to a full modelling approach. In addition to the model simplification, an approach to further improve the simulation speed, through a specific implementation of the differential equation solver, is also considered. To verify the accuracy of the proposed model, different tests with both open-loop and closed-loop flyback converters are performed. The results from both simulation and experiment show good agreement in all the test cases

    Primary-side sensing for a yback converter in both continuous and discontinuous conduction mode

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    Primary-side sensing is an observer-based approach to estimate the out- put voltage of yback converters from a primary winding (or an auxiliary winding). Various observer-laws have been recently developed for yback converters operating in discontinuous conduction mode (DCM). The extension to continuous conduction mode (CCM), however, has not been considered due to the diculties in compensating for the voltage drop in the secondary winding. From the possibility to predict the winding volt- age drop using the magnetizing current and the transformer model, this paper presents a new observer method that can work accurately and smoothly in both CCM and DCM. The methodology can be combined with any controller to provide either output voltage regulation or output current regulation. The proposed sensing technique is veried by simulation

    Real world CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars.

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    In this study CO2 and NOx emissions from 149 Euro 5 and 6 diesel, gasoline and hybrid passenger cars were compared using a Portable Emissions Measurement System (PEMS). The models sampled accounted for 56% of all passenger cars sold in Europe in 2016. We found gasoline vehicles had CO2 emissions 13-66% higher than diesel. During urban driving, the average CO2 emission factor was 210.5 (sd. 47) gkm-1 for gasoline and 170.2 (sd. 34) gkm-1 for diesel. Half the gasoline vehicles tested were Gasoline Direct Injection (GDI). Euro 6 GDI engines <1.4ℓ delivered ~17% CO2 reduction compared to Port Fuel Injection (PFI). Gasoline vehicles delivered an 86-96% reduction in NOx emissions compared to diesel cars. The average urban NOx emission from Euro 6 diesel vehicles 0.44 (sd. 0.44) gkm-1 was 11 times higher than for gasoline 0.04 (sd. 0.04) gkm-1. We also analysed two gasoline-electric hybrids which out-performed both gasoline and diesel for NOx and CO2. We conclude action is required to mitigate the public health risk created by excessive NOx emissions from modern diesel vehicles. Replacing diesel with gasoline would incur a substantial CO2 penalty, however greater uptake of hybrid vehicles would likely reduce both CO2 and NOx emissions. Discrimination of vehicles on the basis of Euro standard is arbitrary and incentives should promote vehicles with the lowest real-world emissions of both NOx and CO2

    Differences in biomechanical determinants of ACL injury risk in Change of Direction tasks between males and females: A systematic review and meta-analysis

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    Background Change of direction (COD) movements are associated with non-contact anterior cruciate ligament (ACL) injuries in multidirectional sports. Females appear at increased risk compared to males, which could be attributable to whole body kinematic strategies and greater multiplanar knee joint loads (KJLs) during COD which can increase ACL loading. Objective The aim of this systematic review and meta-analysis was to examine and quantitatively synthesise the evidence for differences between males and females regarding KJLs and their biomechanical determinants (whole body kinematic strategies determining KJLs) during COD tasks. Methods Databases including SPORTDiscus, Web of Science, and PubMed were systematically searched (July 2021–June 2023) for studies that compared differences in knee joint loads and biomechanical determinants of KJLs during COD between males and females. Inclusion criteria were: (1) females and males with no prior history of ACL injury (18–40 years); (2) examined biomechanical determinants of KJLs and/ or KJLs during COD tasks > 20°; (3) compared ≄ 1 outcome measure between males and females. Studies published between 2000 and 2023 examining a cutting task > 20° with a preceding approach run that compared KJLs or the whole body multiplanar kinematics associated with them, between sexes, using three-dimensional motion analysis. Results This meta-analysis included 17 studies with a pooled sample size of 451 participants (227 males, 224 females). Meta-analysis revealed females displayed significantly less peak knee flexion during stance (SMD: 0.374, 95% CI 0.098–0.649, p = 0.008, I2: 0%); greater knee abduction at initial contact (IC) (SMD: 0.687, 95% CI 0.299–1.076, p = 0.001, I2: 55%); less hip internal rotation (SMD: 0.437, 95% CI 0.134–0.741, p = 0.005, I2: 34%) and hip abduction at IC (SMD: −0.454, 95% CI 0.151–0.758, p = 0.003, I2: 33%). No significant differences were observed between males and females for any internal or externally applied KJLs. All retrieved studies failed to control for strength, resistance training or skill history status. Conclusion No differences were observed in KJLs between males and females despite females displaying greater knee abduction at IC and less peak knee flexion during the stance phase of CODs, which are visual characteristics of non-contact ACL injury. Further research is required to examine if this translates to a similar injury risk, considering morphological differences in strain characteristics of the ACL between males and females. This observation may in part explain the disproportionate ACL injury incidence in female multidirectional athletes. Further higher quality controlled research is required whereby participants are matched by skill training history, resistance training history and strength status to ensure an appropriate comparison between males and females

    p-p' System with B-field, Branes at Angles and Noncommutative Geometry

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    We study the generic p−pâ€Čp-p^\prime system in the presence of constant NS 2-form BijB_{ij} field. We derive properties concerning with the noncommutativity of D-brane worldvolume, the Green functions and the spectrum of this system. In the zero slope limit, a large number of light states appear as the lowest excitations in appropriate cases. We are able to relate the energies of the lowest states after the GSO projection with the configurations of branes at angles. Through analytic continuation, the system is compared with the branes with relative motion.Comment: 21 pages, Latex. References regarding to section 3 and 4 added. Typos correcte

    Blood pressure and cardiac autonomic adaptations to isometric exercise training: A randomized sham‐controlled study

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    Isometric exercise training (IET) is increasingly cited for its role in reducing resting blood pressure (BP). Despite this, few studies have investigated a potential sham effect attributing to the success of IET, thus dictating the aim of the present study. Thirty physically inactive males (n = 15) and females (n = 15) were randomly assigned into three groups. The IET group completed a wall squat intervention at 95% peak heart rate (HR) using a prescribed knee joint angle. The sham group performed a parallel intervention, but at an intensity (<75% peak HR) previously identified to be inefficacious over a 4-week training period. No-intervention controls maintained their normal daily activities. Pre- and post-measures were taken for resting and continuous blood pressure and cardiac autonomic modulation. Resting clinic and continuous beat-to-beat systolic (−15.2 ± 9.2 and −7.3 ± 5.6 mmHg), diastolic (−4.6 ± 5 and −4.5 ± 5.1), and mean (−7 ± 4.2 and −7.5 ± 5.3) BP, respectively, all significantly decreased in the IET group compared to sham and no-intervention control. The IET group observed a significant decrease in low-frequency normalized units of heart rate variability concurrent with a significant increase in high-frequency normalized units of heart rate variability compared to both the sham and no-intervention control groups. The findings of the present study reject a nonspecific effect and further support the role of IET as an effective antihypertensive intervention. Clinical Trials ID: NCT05025202

    Blood pressure and cardiac autonomic adaptations to isometric exercise training: A randomized sham-controlled study

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    Isometric exercise training (IET) is increasingly cited for its role in reducing resting blood pressure (BP). Despite this, few studies have investigated a potential sham effect attributing to the success of IET, thus dictating the aim of the present study. Thirty physically inactive males (n=15) and females (n=15) were randomly assigned into 3 groups. The IET group completed a wall-squat intervention at 95% peak heart rate (HR) using a prescribed knee joint angle. The sham group performed a parallel intervention, but at an intensity (<75% peak HR) previously identified to be inefficacious over a 4-week training period. No-intervention controls maintained their normal daily activities. Pre- and post-measures were taken for resting and continuous blood pressure and cardiac autonomic modulation. Resting clinic and continuous beat to beat systolic (-15.2±9.2 and -7.3±5.6 mmHg), diastolic (-4.6±5 and -4.5±5.1) and mean (-7±4.2 and -7.5±5.3) BP, respectively, all significantly decreased in the IET group compared to sham and no-intervention control. The IET group observed a significant decrease in low frequency normalised units of heart rate variability concurrent with a significant increase in high frequency normalised units of heart rate variability compared to both the sham and no-intervention control groups. The findings of the present study reject a non-specific effect and further support the role of IET as an effective anti-hypertensive intervention

    Speckle tracking echocardiography: new ways of translational approaches in preeclampsia to detect cardiovascular dysfunction

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    Several studies have shown that women with a preeclamptic pregnancy exhibit an increased risk of cardiovascular disease. However, the underlying molecular mechanisms are unknown. Animal models are essential to investigate the causes of this increased risk and have the ability to assess possible preventive and therapeutic interventions. Using the latest technologies such as speckle tracking echocardiography (STE), it is feasible to map subclinical changes in cardiac diastolic and systolic function as well as structural changes of the maternal heart. The aim of this work is to compare cardiovascular changes in an established transgenic rat model with preeclampsia-like pregnancies with findings from human preeclamptic pregnancies by STE. The same algorithms were used to evaluate and compare the changes in echos of human and rodents. Parameters of functionality like global longitudinal strain (animal -23.54 ± 1.82 % vs. -13.79 ± 0.57 %, human -20.60 ± 0.47 % vs. -15.45 ± 1.55 %) as well as indications of morphological changes like relative wall thickness (animal 0.20 ± 0.01 vs. 0.25 ± 0.01, human 0.34 ± 0.01 vs. 0.40 ± 0.02) are significantly altered in both species after preeclamptic pregnancies. Thus, the described rat model simulates the human situation quite well and is a valuable tool for future investigations regarding cardiovascular changes. STE is a unique technique which can be applied in animal models and human with a high potential to uncover cardiovascular maladaptation and subtle pathologies
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