1,802 research outputs found
Accounting for the relationship between money and interest rates
No full textIn time-series from the United States, the relationship between the money to income ratio and the nominal interest rate is a negative and stable one. In Swedish data, there is no such stable relationship. In this paper, we argue that this difference can be explained by the differences in the shock processes that have hit the two countries. Using a dynamic general equilibrium model driven by shock processes estimated to fit the two countries, we find that we can account for the main properties of the data remarkably wel
Tax distortions in Sweden and the United States
No full textWe calculate the welfare costs of distortionary taxation (including inflation) in models calibrated for the United States and Sweden. The welfare costs are calculated using comparative steady state as well as dynamic analysis, where we take the costs of transition from the distorted to the optimal steady state into account. We also calculate the welfare costs of adding stochastic fluctuations. Our main finding is that the total welfare costs of the distortionary taxes including the distortionary effects of inflation are about five times higher in Sweden than in the United States. Meanwhile, stochastic fluctuations in policy turn out to have a relatively small impact on welfare.<br/
Investigation of High Pressure Turbine End-Wall Film Cooling Performances under Realistic Inlet Conditions
No full textThe mean value of turbine entry temperature increased to improve efficiency and specific power. Due to the combustor characteristics, thermal and aero-dynamics non-uniformities can be individuated at the turbine inlet section. Then, a further increase in the inlet temperature will generate in the next years harmful conditions also for vane end-walls. In other words, it is necessary to use realistic turbine inlet temperature and velocity profiles to evaluate the effects generated by this design tendency. The objective of the present work is to analyze a cooled high-pressure vane in terms of adiabatic effectiveness and aerodynamic behavior. An end-wall cooling geometry with both fan-shaped and cylindrical holes, tested by EPFL in the frame of the EU funded TATEF2 project, has been chosen. Numerical analysis has been performed by the Energy Engineering Department of the University of Florence. Inlet non-uniformity of total temperature and velocity profile has been considered as representative of realistic situations. According to the distributions of Cd, BR and ηaw, a steady RANS simulation is able to reproduce the experimental data with an error slightly higher that the one of the measurements. Once the inlet T0 profile is imposed, an increase of 100% in the laterally averaged ηaw, generated by the radial T0 distribution can be achieved. The improved performance is visible on the 2D maps, too. The gain in cooling efficiency is limited by the inlet swirl, whose presence modifies the horseshoe vortex development and generates a stronger passage vortex with a detrimental effect for the platform cooling. Therefore, an accurate estimation of the inlet conditions is vital for machine reliability.GT
Modeling the dialogue aspects of an information system.
Get PDFIn this paper we investigate techniques offered by current object-oriented development methods for the specification of the user-system dialogue aspect of a software system. Current development methods do not give very extensive guidelines on how to model this aspect and the available techniques need some refinement and elaboration to fit this particular task in the software specification process. The paper first compares a number of approaches. The common elements of these approaches are summarized and further developed into one comprehensive set of techniques that addresses the needs of functional requirements analysis.
Computing the minimum EDF feasible deadline in periodic systems
No full textIn most real-time applications, deadlines are artifices that need to be enforced to meet different performance requirements. For example, in periodic task sets, jitter requirements can be met by assigning suitable relative deadlines and guaranteeing the feasibility of the schedule. This paper presents a method (called minD) for calculating the minimum EDF-feasible deadline of a real-time task. More precisely, given a set of periodic tasks with hard real-time requirements, which is feasible under EDF, the proposed algorithm allows computing the shortest deadline that can be assigned to an arbitrary task in the set, or to a new incoming task (periodic or aperiodic), still preserving the EDF feasibility of the new task set. The algorithm has a pseudo polynomial complexity and handles arbitrary relative deadlines, which can be less than, equal to, or greater than periods.©2006 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.</p
Existential prime convex Jonsson theories and their models
Get PDFThis article is devoted to the study of the model - theoretic properties of special subclasses of Jonsson theories and their classes of models. Namely, introduce a new class of Jonsson theories is existentially prime convex Jonsson theories. The notion of convexity of theory was previously known, it was introduced by A.Robinson. The notion of existential simplicity introduced by the author of this article. Both conditions form a broad natural classes of theories. Thus two natural restrictions on Jonsson define a new class of theories with rich model - theoretic properties. Besides defined formulation of the problem, which define a new direction in the study Jonsson theories
The Forecasting Properties of Survey-Based Wage-Growth Expectations
Get PDFIn this paper, we evaluate survey-based wage-growth expectations in Sweden. Results show that the expectations are neither unbiased nor efficient forecasts. Evaluating out-of-sample forecasting performance, we find that the survey participants generally perform worse than a con-stant forecast based on reasonable assumptions regarding the inflation target and productivity growth. Our findings indicate that caution should be exercised when relying on these data for policymaking.Survey data;
Methodological aspects on carotid artery intervention
No full textIn Sweden, approximately 25000 patients suffer a cerebral infarction (stroke) annually. Stroke ranks as the third-leading cause of death, and is the leading cause of functional impairment. Carotid artery stenosis accounts for approximately 15% of all strokes and almost all of these are theoretically preventable. There are two conceptually different invasive methods used to treat carotid stenosis: carotid artery stenting (CAS) and carotid endarterectomy (CEA). There are various aspects of these treatments that remain to be evaluated in order to minimize the risks of poor outcome, namely: any differences in short-term and long-term outcomes after CEA or CAS, the potential risks of CAS early after a previous transient ischaemic attack (TIA)/stroke, and the methods to indicate the need of shunting during CEA. Furthermore, since data from randomised controlled trials (RCTs) are often from specialized high volume centres with selected patients, it is important to evaluate population-based results after CAS and CEA.The overall aim of this thesis was to investigate aspects of invasive treatment of carotid artery stenosis, in particular the outcome following endovascular treatment (CAS), and the efficacy of near-infrared spectroscopy in predicting selective shunt use during CEA. The outcome after endovascular treatment was investigated in three cohort studies (study I, II, and III). In study I, we analysed Swedish national short-term results of CAS and CEA and compared a high-volume centre with national results for CAS. In study II we evaluated the procedural risk of CAS, in relation to time from previous TIA /stroke. Study III assessed the long-term population-based outcomes after CAS as compared to CEA. In study IV, a multi-centre diagnostic study, we evaluated the ability of near-infrared spectroscopy (NIRS) to predict cerebral ischaemia during CEA.Study I was a retrospective single-centre review of all consecutive patients treated with CAS at Södersjukhuset between 2004-2011. These results were compared to data from the Swedish national registry for vascular surgery (Swedvasc), where data from all patients treated with CAS or CEA during the same period was extracted. We found that the Swedish national results for CAS were inferior to CEA, but also that it was possible to achieve acceptable results with CAS in a high volume centre. During the study period 464 CAS procedures were performed in Sweden, with 208 of them performed at Södersjukhuset. The stroke and death rate at 30 days among patients in Sweden (Södersjukhuset excluded) was 7.4%. In Södersjukhuset, the stroke and death rate was 2.9%. The results for CAS on a national basis improved over time, the stroke and death rate during the first half of the period was 6.4%, compared to 3.6% in the second part of the study period, which was probably due to the learning curve for the procedure.In study II, all CAS performed for symptomatic carotid stenosis between 2005-2014, were included in a retrospective analysis. Study II revealed that it was safe to perform CAS early (within 1 week), following a TIA/stroke. The stroke and death rate for patient treated within 7 days from neurologic symptom was 4.1%, compared to 6.3% between day 8-14, 4.8% between day 15-28, and 3.6% between days 29-180.The long-term results after CAS in Sweden were examined in study III. In this study, all primary CAS procedures registered in Swedvasc were included (all reoperations were excluded). We compared 409 CAS patients to a control group treated with CEA. The control group was matched with respect to known confounding factors. Postoperative stroke was identified by cross matching the cohort with the In-patient registry. Median follow-up time was 4.1 years, and follow-up data was almost complete. By using Cox regression, we found a substantial (59%) increased risk for late(>30 days) stroke or death for patients treated with CAS compared to CEA. This increased risk was mainly due to an increased risk of ipsilateral stroke during long-term follow-up.In study IV, we have shown that near-infrared spectroscopy has a high sensitivity and acceptable specificity to predict cerebral ischemia during CEA. When a cut-off point of 9% relative decrease in regional SO2 during carotid clamping was chosen, the sensitivity for detecting cerebral ischemia was 95%, and the specificity 81%. This was clearly superior to the conventional and widespread technique of measuring, “stump pressure”.In conclusion, the national population-based results for CAS were inferior to CEA, both short- and long-term. The short-term results after CAS in Sweden have improved over time, and acceptable results can be achieved in high volume centres. If CAS is performed due to symptomatic stenosis it could be performed early after onset of neurologic symptoms. Near-infrared spectroscopy is a reliable method for selective shunting during CEA and superior to stump pressure.List of scientific papersI. Outcome after 7 years of Carotid Artery Stenting and Endarterectomy in Sweden – Single Centre and National Results. David Lindström, Magnus Jonsson, Johan Formgren, Martin Delle, Stefan Rosfors, Peter Gillgren. European journal of vascular and endovascular surgery. 2012;43(5):499-503. https://doi.org/10.1016/j.ejvs.2012.01.024 II. Peri-procedural Risk with Urgent Carotid Artery Stenting: A Population based Swedvasc Study. Magnus Jonsson, Peter Gillgren, Anders Wanhainen, Stefan Acosta, David Lindström. European journal of vascular and endovascular surgery. 2015;49(5):506-12. https://doi.org/10.1016/j.ejvs.2015.01.007 III. Long-Term Outcome After Carotid Artery Stenting - A Population-Based Matched Cohort Study. Magnus Jonsson, David Lindström, Peter Gillgren, Anders Wanhainen, Jonas Malmstedt. Stroke. 2016;47:2083-2089. https://doi.org/10.1161/STROKEAHA.116.013018 IV. Near-infrared Spectroscopy (NIRS) as Predictor for Shunt Need During Carotid Endarterectomy. Magnus Jonsson, David Lindström, Anders Wanhainen, Khatereh Djavani-Gidlund, Peter Gillgren. [Submitted]</p
Real-time communication support for cooperative, infrastructure-based traffic safety applications
Get PDFThe implementation of ITS (Intelligent Transport Systems) services offers great potential to improve the level of safety, efficiency and comfort on our roads. Although cooperative traffic safety applications rely heavily on the support for real-time communication, the Medium Access Control (MAC) mechanism proposed for the upcoming IEEE 802.11p standard, intended for ITS applications, does not offer deterministic real-time support, that is, the access delay to the common radio channel is not upper bounded. To address this problem, we present a framework for a vehicle-to-infrastructure-based (V2I) communication solution extending IEEE 802.11p by introducing a collision-free MAC phase assigning each vehicle an individual priority based on its geographical position, its proximity to potential hazards and the overall road traffic density. Our solution is able to guarantee the timely treatment of safety-critical data, while minimizing the required length of this real-time MAC phase and freeing bandwidth for best-effort services (targeting improved driving comfort and traffic efficiency). Furthermore, we target fast connection setup, associating a passing vehicle to an RSU (Road Side Unit), and proactive handover between widely spaced RSUs. Our real-time MAC concept is evaluated analytically and by simulation based on a realistic task set from a V2I highway merge assistance scenario.Copyright © 2011 Annette Böhm and Magnus Jonsson. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</p
Labor-Force Participation Rates and the Informational Value of Unemployment Rates: Evidence from Disaggregated US Data
Get PDFThe informational value of the aggregate US unemployment rate has recently been questioned be-cause of a unit root in the labor-force participation rate; the lack of mean reversion implies that long-run changes in unemployment rates are highly unlikely to reflect long-run changes in jobless-ness. This paper shows that this critique also extends to unemployment rates for sub-populations, such as prime-aged males.Unit-root test;
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