771 research outputs found

    Testing Long-Run Purchasing Power Parity under Exchange Rate Targeting

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    The present paper exploits the idea that empirical estimates of the long-run PPP relationship may compound two distinct influences coming from the behavior of market participants and policy makers when the latter are targeting the exchange rate. This tends to bias tests of long-run PPP against its acceptance. The validity of the theoretical arguments is assessed by drawing on the experience of two European Union countries, Greece and France for the post-Bretton Woods period. Estimation biases due to the omission of policy effects are found to be significant only in the case of Greece. For France, our test results provide evidence bearing on the effectiveness of the competitive disinflation strategy pursued by the French authorities.Long-run PPP; exchange rate targeting; intervention policy; multivariate cointegration

    Gravimetric geoid refinement using high resolution gravity and terrain data

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    In regions where additional, spatially dense gravity and terrain information are available to augment existing data, a gravimetric determination of the geoid can be improved by incorporating these new data. In this study, 4,016 additional gravity observations, measured on a near-regular 2km by 3km grid in Western Australia have been used to compute a gravimetric geoid model using fast Fourier transform (FFT) techniques. A digital terrain model is also used during the geoid computations, which is derived from gravity station elevations and spot heights in the area. Using 21 spirit-levelled Australian Height Datum (AHD) heights in conjunction with Global Positioning System (GPS) ellipsoidal heights as control data, the standard deviation of the new gravimetric geoid is ±0.0824m. This represents a 31% improvement over the existing AUSGEOID93 gravimetric geoid and a 48% improvement over the OSU91A global geopotential model. Of these improvements, approximately 10% is due to the additional gravity data and approximately 1% is due to the terrain effects; the remainder is due to the dense gridding of the data prior to the FFT computations

    Residual mechanical characteristics and spalling resistance of fiber reinforced self-compacting concretes exposed to elevated temperatures

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    h i g h l i g h t s " We examined the performance at elevated temperatures of two normally vibrated concretes and six self compacted concretes. " The strength classes of the mixtures were C25/30 and C30/37. " Polypropylene fibres with a length of 6 and 12 mm were used to produce fibre reinforced SCC. " The spalling tendency was increased for specimens of higher strength class irrespective of the mixture type (SCC or NVC). " Both 6 m and 12 mm fibres had the same positive effect since all fiber reinforced SCC mixtures did not perform any spalling. a r t i c l e i n f o t r a c t The study presented in this paper concerns the effect that polypropylene fibres have on the properties of SCC of different strength classes when exposed to elevated temperatures. A total of six different SCC and two normal concrete mixtures were produced. The strength classes of the mixtures were C25/30 and C30/ 37. The specimens produced were placed at the age of 120 days in an electrical furnace and the heat was applied with a rate of 5°C/min. The tested temperatures were 300°C and 600°C. Once reached, the maximum temperature was maintained for 1 h. Then the specimens were naturally cooled down to ambient temperature in the furnace. The properties measured after heat exposures were the compressive strength, splitting tensile strength, water capillary absorption and ultrasonic pulse velocity. It was noticed that, the spalling tendency was increased for specimens of higher strength class C30/37 irrespective of the mixture type (SCC or NVC). Such an explosive behavior was not observed when polypropylene fibers were added in the mixtures; however, in this case the residual mechanical characteristics of concretes were significantly reduced

    Total score of athleticism: Profiling strength and power characteristics in professional soccer players following anterior cruciate ligament reconstruction to assess return to sport readiness

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    Single leg drop jump (SLDJ) assessment is commonly used during the later stages of rehabilitation to identify residual deficits in reactive strength but the effects of physical capacity on kinetic and kinematic variables in male soccer players following ACL reconstruction remains unknown. Isokinetic knee extension strength, kinematics from an inertial measurement unit 3D system and SLDJ performance variables and mechanics derived from a force plate were measured in 64 professional soccer players (24.7 ± 3.4 years) prior to return to sport (RTS). SLDJ between-limb differences were measured (part 1) and players were divided into tertiles based on isokinetic knee extension strength (weak, moderate and strong) and reactive strength index (RSI) (low, medium and high) (part 2). Moderate to large significant differences between the ACL reconstructed and uninjured limb in SLDJ performance (d = 0.92 – 1.05), kinetic (d = 0.62 – 0.71) and kinematic variables (d = 0.56) were evident. Stronger athletes jumped higher (p = 0.002; d = 0.85), produced greater concentric (p = 0.001; d = 0.85) and eccentric power (p = 0.002; d = 0.84). Similar findings were present for RSI, but the effects were larger (d = 1.52 – 3.84). Weaker players, and in particular those who had lower RSI, displayed landing mechanics indicative of a “stiff” knee movement strategy. SLDJ performance, kinetic and kinematic differences were identified between-limbs in soccer players at the end of their rehabilitation following ACL reconstruction. Players with lower knee extension strength and RSI displayed reduced performance and kinetic strategies associated with increased injury risk

    Single leg drop jump is affected by physical capacities in male soccer players following ACL reconstruction

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    Single leg drop jump (SLDJ) assessment is commonly used during the later stages of rehabilitation to identify residual deficits in reactive strength but the effects of physical capacity on kinetic and kinematic variables in male soccer players following ACL reconstruction remains unknown. Isokinetic knee extension strength, kinematics from an inertial measurement unit 3D system and SLDJ performance variables and mechanics derived from a force plate were measured in 64 professional soccer players (24.7 ± 3.4 years) prior to return to sport (RTS). SLDJ between-limb differences were measured (part 1) and players were divided into tertiles based on isokinetic knee extension strength (weak, moderate and strong) and reactive strength index (RSI) (low, medium and high) (part 2). Moderate to large significant differences between the ACL reconstructed and uninjured limb in SLDJ performance (d = 0.92 – 1.05), kinetic (d = 0.62 – 0.71) and kinematic variables (d = 0.56) were evident. Stronger athletes jumped higher (p = 0.002; d = 0.85), produced greater concentric (p = 0.001; d = 0.85) and eccentric power (p = 0.002; d = 0.84). Similar findings were present for RSI, but the effects were larger (d = 1.52 – 3.84). Weaker players, and in particular those who had lower RSI, displayed landing mechanics indicative of a “stiff” knee movement strategy. SLDJ performance, kinetic and kinematic differences were identified between-limbs in soccer players at the end of their rehabilitation following ACL reconstruction. Players with lower knee extension strength and RSI displayed reduced performance and kinetic strategies associated with increased injury risk

    Catheter ablation of atrial fibrillation in patients with left ventricular dysfunction

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    There is a complex interplay between atrial fibrillation and congestive heart failure. These two clinical entities often coexist, resulting in significant morbidity, affecting prognosis and rendering their management even more challenging. New nonpharmacologic therapies are emerging and may alter the management of these patients. Among them, catheter ablation of atrial fibrillation seems to be a promising therapeutic approach as it leads to improvement of cardiac function, symptoms, exercise capacity, and quality of life. This article reviews the role of catheter ablation in contemporary management of atrial fibrillation among patients with left ventricular dysfunction

    A comparison of strength and power characteristics prior to anterior cruciate ligament rupture and at the end of rehabilitation in professional soccer players

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    Background: Strength and power is often reduced on the involved vs. contralateral limb and healthy controls following anterior cruciate ligament (ACL) reconstruction but no study has compared to pre-injury values at the time of return to sport (RTS). Hypothesis: Divergent recovery patterns in strength and power characteristics will be present at RTS relative to pre-injury baseline data and healthy matched controls. Study design: Cohort study Level of evidence: Level 3 Methods: Isokinetic strength tests, bilateral and single leg countermovement jumps (CMJ; SLCMJ) were measured prior to ACL rupture in 20 professional soccer players. These then had surgical reconstruction (ACL group) and completed follow up testing prior to RTS. Healthy controls (uninjured group) were tested at the same time as the ACL group pre-injury. Values recorded at RTS of the ACL group were compared to pre-injury. We also compared the uninjured and ACL groups at baseline and RTS. Results: Compared to pre-injury, ACL normalised quadriceps peak torque of the involved limb (% difference = -7%), SLCMJ height (% difference = -12.08%) and Reactive Strength Index modified (RSImod) (% difference = -5.04%) were reduced following ACL reconstruction. No significant reductions in CMJ height, RSImod and relative peak power were indicated at RTS in the ACL group when compared to pre-injury values but deficits were present relative to controls. The uninvolved limb significantly improved quadriceps (% difference = 9.34%) and hamstring strength (% difference = 7.36%) from pre-injury to RTS. No significant differences from baseline were shown in SLCMJ height, power and reactive strength of the uninvolved limb following ACL reconstruction. Conclusion: Strength and power in professional soccer players at RTS following ACL reconstruction were often reduced compared to preinjury values and matched healthy controls. Clinical relevance: Deficits were more apparent in the SLCMJ suggesting dynamic and multijoint unilateral force production is an important component of rehabilitation. Use of the uninvolved limb and normative data to determine recovery may not always be appropriate

    Binary particle swarm optimized 2 Ă— 2 power splitters in a standard foundry silicon photonic platform

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    Compact power splitters designed ab initio using binary particle swarm optimization in a 2D mesh for a standard foundry silicon photonic platform are studied. Designs with a 4.8  μm×4.8  μm footprint composed of 200  nm×200  nm and 100  nm×100  nm cells are demonstrated. Despite not respecting design rules, the design with the smaller cells had lower insertion losses and broader bandwidth and showed consistent behavior across the wafer. Deviations between design and experiments point to the need for further investigations of the minimum feature dimensions

    Variation in Outcome Reporting in Studies of Fertility-Sparing Surgery for Cervical Cancer: a Systematic Review.

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    BACKGROUND: Cervical cancer affects 3,197 women in the UK, and 604000 women worldwide annually, with peak incidence seen between 30-34 years of age. For many, fertility-sparing surgery is an appealing option where possible. However, absence of large-scale data, along with a notable variation in reported outcomes in relevant studies may undermine future efforts for consistent evidence synthesis. OBJECTIVES: To systematically review the reported outcomes measured in studies that include women who underwent fertility-sparing surgery for cervical cancer and identify whether variation exists. SEARCH STRATEGY: We searched MEDLINE, EMBASE, and CENTRAL from inception to February 2019. SELECTION CRITERIA: Randomised controlled trials, cohort and observational studies, and case studies of more than 10 participants from January 1990 to date. DATA COLLECTION AND ANALYSIS: Study characteristics and all reported treatment outcomes. MAIN RESULTS: 104 studies with a sum of 9535 participants were identified. Most studies reported on oncological outcomes (97/104), followed by fertility and pregnancy (86/104), post-operative complications (74/104), intra-operative complications (72/104), and quality of life (5). There were huge variation and heterogeneity in reported outcomes, with only 12% being good quality and 87% being of poor quality. CONCLUSIONS: There is significant heterogeneity in the reported outcomes. An agreed Core Outcome Set (COS) is necessary for future studies to effectively harmonise reported outcomes that are measurable and relevant to patients, clinicians, and researchers. This systematic review sets the groundwork for the development of a COS for fertility-sparing surgery in cervical cancer

    Activity Participation Among Children With Autism Spectrum Disorder

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    OBJECTIVE. The purpose of this study was to empirically derive dimensions of activity participation among a sample of school-age children with autism spectrum disorder (ASD; n = 713). Additionally, we examined the associations between dimensions of activity participation and child characteristics (i.e., chronological age, autism severity, gender) and family demographics (i.e., maternal education)
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