764 research outputs found

    The new keynesian approach to dynamic general equilibrium modeling: models, methods, and macroeconomic policy evaluation

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    This chapter aims to provide a hands-on approach to New Keynesian models and their uses for macroeconomic policy analysis. It starts by reviewing the origins of the New Keynesian approach, the key model ingredients and representative models. Building blocks of current-generation dynamic stochastic general equilibrium (DSGE) models are discussed in detail. These models address the famous Lucas critique by deriving behavioral equations systematically from the optimizing and forward-looking decision-making of households and firms subject to well-defined constraints. State-of-the-art methods for solving and estimating such models are reviewed and presented in examples. The chapter goes beyond the mere presentation of the most popular benchmark model by providing a framework for model comparison along with a database that includes a wide variety of macroeconomic models. Thus, it offers a convenient approach for comparing new models to available benchmarks and for investigating whether particular policy recommendations are robust to model uncertainty. Such robustness analysis is illustrated by evaluating the performance of simple monetary policy rules across a range of recently-estimated models including some with financial market imperfections and by reviewing recent comparative findings regarding the magnitude of government spending multipliers. The chapter concludes with a discussion of important objectives for on-going and future research using the New Keynesian framework

    A new comparative approach to macroeconomic modeling and policy analysis

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    In the aftermath of the global financial crisis, the state of macroeconomic modeling and the use of macroeconomic models in policy analysis has come under heavy criticism. Macroeconomists in academia and policy institutions have been blamed for relying too much on a particular class of macroeconomic models. This paper proposes a comparative approach to macroeconomic policy analysis that is open to competing modeling paradigms. Macroeconomic model comparison projects have helped produce some very influential insights such as the Taylor rule. However, they have been infrequent and costly, because they require the input of many teams of researchers and multiple meetings to obtain a limited set of comparative findings. This paper provides a new approach that enables individual researchers to conduct model comparisons easily, frequently, at low cost and on a large scale. Using this approach a model archive is built that includes many well-known empirically estimated models that may be used for quantitative analysis of monetary and fiscal stabilization policies. A computational platform is created that allows straightforward comparisons of models’ implications. Its application is illustrated by comparing different monetary and fiscal policies across selected models. Researchers can easily include new models in the data base and compare the effects of novel extensions to established benchmarks thereby fostering a comparative instead of insular approach to model development

    Ethikmanagement in der Naturkostbranche - Eine Machbarkeitsstudie

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    In mehrfacher Weise hat es sich als fruchtbares und aussichtsreiches Projekt erwiesen, die Themen „Naturkostbranche“ und „Ethikmanagement“ als die beiden Untersuchungsgegenstände dieser Machbarkeitsstudie zusammenzuführen. Zunächst hat man es bei der Naturkostbranche mit einem aus unternehmensethischer Perspektive außergewöhnlichen Wirtschaftszweig zu tun. Denn er zeichnet sich – wie die Studie anschaulich belegt – in vielfältiger Weise durch einen besonderen moralisch-gesellschaftlichen Anspruch aus. Diese Ansprüche bewusster und wirkungsvoller zur praktischen Geltung zu bringen, wäre die Aufgabe eines Ethikmanagementsystems. Die aktuelle Situation der Naturkostunternehmen mit ihren Umbrüchen und Risiken, unterstreicht zudem die Sinnhaftigkeit von Ethikmanagement. Indem die konzeptionellen Vorschläge von Ethikmanagementsystemen mit ihren praktischen Instrumenten vor der spezifischen Situation der Unternehmen gespiegelt wurden, konnten auch vielfältige Anregungen für ihre erforderliche branchenbezogene Ausgestaltung gewonnen werden. Neben praktischen Erfolgsfaktoren für Ethikmanagement liefert die Studie auch Hinweise für die strategische Weiterentwicklung einer gesellschaftsorientierten Unternehmenspolitik, die über die bisherige Entwicklung in den Naturkostunternehmen hinausweist: Die dauerhafte Verankerung normativer Orientierungen in wachsenden Unternehmen, das Auf-den-Weg-bringen (auch) moralisch inspirierter Innovationen und – nicht zuletzt – der offene und konstruktive Austausch in Markt und Gesellschaft über ein ethisch verantwortungsvolles Engagement beim Geschäftsgebaren und darüber hinaus – all dies sind Herausforderungen, die gerade die Naturkostunternehmen unter Zuhilfenahme eines Ethikmanagementsystems erfolgreich zur eigenen Profilbildung nutzen könnten. Daher lautet das Fazit dieser Machbarkeitsstudie, dass die Einführung von Ethikmanagementsystemen in Naturkostunternehmen ein nicht nur machbares, sondern auch höchst vielversprechendes Projekt wäre

    Effect of Lateral Sliding Calcaneus Osteotomy on Tarsal Tunnel Pressure

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    Background: Lateral sliding calcaneus osteotomies are common procedures to correct hindfoot varus deformities. Shifting the calcaneal tuberosity laterally (lateralization) can lead to tarsal tunnel pressure increase and tibial nerve palsy. The purpose of this cadaveric biomechanical study was to investigate the correlation of lateralization and pressure increase underneath the flexor retinaculum. Methods: The pressure in the tarsal tunnel of 12 Thiel-fixated human cadaveric lower legs was measured in different foot positions and varying degrees of calcaneal lateralization. Results: The mean pressure increased from plantarflexion (PF) to neutral position (NP) and from NP to hindfoot dorsiflexion (DF), and with increasing amounts of lateralization of the calcaneal tuberosity. The mean baseline pressure in PF was 1.5, in NP 2.2, and in DF 6.5 mmHg and increased to 8.1 in PF, 18.4 in NP, and 33.1 mmHg with 12 mm of lateralization. The release of the flexor retinaculum significantly lowered the pressure. Conclusion: Increasing pressures were found in the tarsal tunnel with increasing lateralization of the tuberosity and with both dorsiflexion and plantarflexion of the ankle. Clinical Relevance: A pre-emptive release of the flexor retinaculum for a lateralization of the calcaneal tuberosity of more than 8 mm should be considered, especially if specific patient risk factors are present. No tibial nerve palsy should be expected with 4 mm of lateralization

    Computational mechanisms of belief updating in relation to psychotic-like experiences

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    Introduction Psychotic-like experiences (PLEs) may occur due to changes in weighting prior beliefs and new evidence in the belief updating process. It is still unclear whether the acquisition or integration of stable beliefs is altered, and whether such alteration depends on the level of environmental and belief precision, which reflects the associated uncertainty. This motivated us to investigate uncertainty-related dynamics of belief updating in relation to PLEs using an online study design. Methods We selected a sample (n = 300) of participants who performed a belief updating task with sudden change points and provided self-report questionnaires for PLEs. The task required participants to observe bags dropping from a hidden helicopter, infer its position, and dynamically update their belief about the helicopter's position. Participants could optimize performance by adjusting learning rates according to inferred belief uncertainty (inverse prior precision) and the probability of environmental change points. We used a normative learning model to examine the relationship between adherence to specific model parameters and PLEs. Results PLEs were linked to lower accuracy in tracking the outcome (helicopter location) (β = 0.26 ± 0.11, p = 0.018) and to a smaller increase of belief precision across observations after a change point (β = −0.003 ± 0.0007, p < 0.001). PLEs were related to slower belief updating when participants encountered large prediction errors (β = −0.03 ± 0.009, p = 0.001). Computational modeling suggested that PLEs were associated with reduced overall belief updating in response to prediction errors (βPE = −1.00 ± 0.45, p = 0.028) and reduced modulation of updating at inferred environmental change points (βCPP = −0.84 ± 0.38, p = 0.023). Discussion We conclude that PLEs are associated with altered dynamics of belief updating. These findings support the idea that the process of balancing prior belief and new evidence, as a function of environmental uncertainty, is altered in PLEs, which may contribute to the development of delusions. Specifically, slower learning after large prediction errors in people with high PLEs may result in rigid beliefs. Disregarding environmental change points may limit the flexibility to establish new beliefs in the face of contradictory evidence. The present study fosters a deeper understanding of inferential belief updating mechanisms underlying PLEs.Peer Reviewe

    Computational mechanisms of belief updating in relation to psychotic-like experiences

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    Introduction: Psychotic-like experiences (PLEs) may occur due to changes in weighting prior beliefs and new evidence in the belief updating process. It is still unclear whether the acquisition or integration of stable beliefs is altered, and whether such alteration depends on the level of environmental and belief precision, which reflects the associated uncertainty. This motivated us to investigate uncertainty-related dynamics of belief updating in relation to PLEs using an online study design. Methods: We selected a sample (n = 300) of participants who performed a belief updating task with sudden change points and provided self-report questionnaires for PLEs. The task required participants to observe bags dropping from a hidden helicopter, infer its position, and dynamically update their belief about the helicopter's position. Participants could optimize performance by adjusting learning rates according to inferred belief uncertainty (inverse prior precision) and the probability of environmental change points. We used a normative learning model to examine the relationship between adherence to specific model parameters and PLEs. Results: PLEs were linked to lower accuracy in tracking the outcome (helicopter location) (beta = 0.26 +/- 0.11, p = 0.018) and to a smaller increase of belief precision across observations after a change point (beta = -0.003 +/- 0.0007, p < 0.001). PLEs were related to slower belief updating when participants encountered large prediction errors (beta = -0.03 +/- 0.009, p = 0.001). Computational modeling suggested that PLEs were associated with reduced overall belief updating in response to prediction errors (beta(PE) = -1.00 +/- 0.45, p = 0.028) and reduced modulation of updating at inferred environmental change points (beta(CPP) = -0.84 +/- 0.38, p = 0.023). Discussion: We conclude that PLEs are associated with altered dynamics of belief updating. These findings support the idea that the process of balancing prior belief and new evidence, as a function of environmental uncertainty, is altered in PLEs, which may contribute to the development of delusions. Specifically, slower learning after large prediction errors in people with high PLEs may result in rigid beliefs. Disregarding environmental change points may limit the flexibility to establish new beliefs in the face of contradictory evidence. The present study fosters a deeper understanding of inferential belief updating mechanisms underlying PLEs

    Defective Secretion of Islet Hormones in Chromogranin-B Deficient Mice

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    Granins are major constituents of dense-core secretory granules in neuroendocrine cells, but their function is still a matter of debate. Work in cell lines has suggested that the most abundant and ubiquitously expressed granins, chromogranin A and B (CgA and CgB), are involved in granulogenesis and protein sorting. Here we report the generation and characterization of mice lacking chromogranin B (CgB-ko), which were viable and fertile. Unlike neuroendocrine tissues, pancreatic islets of these animals lacked compensatory changes in other granins and were therefore analyzed in detail. Stimulated secretion of insulin, glucagon and somatostatin was reduced in CgB-ko islets, in parallel with somewhat impaired glucose clearance and reduced insulin release, but normal insulin sensitivity in vivo. CgB-ko islets lacked specifically the rapid initial phase of stimulated secretion, had elevated basal insulin release, and stored and released twice as much proinsulin as wildtype (wt) islets. Stimulated release of glucagon and somatostatin was reduced as well. Surprisingly, biogenesis, morphology and function of insulin granules were normal, and no differences were found with regard to β-cell stimulus-secretion coupling. We conclude that CgB is not required for normal insulin granule biogenesis or maintenance in vivo, but is essential for adequate secretion of islet hormones. Consequentially CgB-ko animals display some, but not all, hallmarks of human type-2 diabetes. However, the molecular mechanisms underlying this defect remain to be determined

    Investigating Alkylated Prodigiosenes and Their Cu(II)-Dependent Biological Activity: Interactions with DNA, Antimicrobial and Photoinduced Anticancer Activity

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    Prodigiosenes are a family of red pigments with versatile biological activity. Their tripyrrolic core structure has been modified many times in order to manipulate the spectrum of activity. We have been looking systematically at prodigiosenes substituted at the C ring with alkyl chains of different lengths, in order to assess the relevance of this substituent in a context that has not been investigated before for these derivatives: Cu(II) complexation, DNA binding, self-activated DNA cleavage, photoinduced cytotoxicity and antimicrobial activity. Our results indicate that the hydrophobic substituent has a clear influence on the different aspects of their biological activity. The cytotoxicity study of the Cu(II) complexes of these prodigiosenes shows that they exhibit a strong cytotoxic effect towards the tested tumor cell lines. The Cu(II) complex of a prodigiosene lacking any alkyl chain excelled in its photoinduced anticancer activity, thus demonstrating the potential of prodigiosenes and their metal complexes for an application in photodynamic therapy (PDT). Two derivatives along with their Cu(II) complexes showed also antimicrobial activity against Staphylococcus aureus strains

    Three-Dimensional High-Resolution Black-Blood Magnetic Resonance Imaging for Detection of Arteritic Anterior Ischemic Optic Neuropathy in Patients With Giant Cell Arteritis

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    Objectives: Arteritic anterior ischemic optic neuropathy (A-AION) caused by inflammatory occlusion of the posterior ciliary arteries is the most common reason for irreversible vision loss in patients with giant cell arteritis. Atypical clinical presentation and negative funduscopy can delay systemic high-dose corticosteroid therapy to prevent impending permanent blindness and involvement of the contralateral eye. The purpose of this study was to assess the diagnostic accuracy of 3-dimensional (3D) high-resolution T1-weighted black-blood magnetic resonance imaging (T1-BB-MRI) for the detection of posterior ciliary artery involvement in patients with giant cell arteritis and funduscopic A-AION. Materials and Methods: After institutional review board approval and informed consent, 27 patients with suspected giant cell arteritis and vision disturbances were included in this monocentric prospective cohort study. Giant cell arteritis was diagnosed in 18 patients according to the diagnostic reference standard (6 men, 73.8 [69.0-78.0] years);14 of those were positive for A-AION. Precontrast and postcontrast 3D T1-BB-MRI was performed in all 27 patients. Two radiologists separately assessed image quality and local fat suppression (4-point scale), visual contrast enhancement (3-point scale), and diagnostic confidence (5-point scale) regarding arteritic posterior ciliary artery involvement. Magnetic resonance imaging findings were assessed in comparison to funduscopy. Statistical analysis included accuracy parameters and interrater agreement. Results: Sensitivity of 3D T1-BB-MRI was 92.9% (95% confidence interval, 66.1%-99.8%) and specificity was 92.3% (95% confidence interval, 64.0%-99.8%) for detection of A-AION-positive patients. Image quality and local fat suppression were assessed with 3.2 +/- 0.8 (median 3) and 3.8 +/- 0.5 (median 4). Visual contrast enhancement with 2.3 +/- 0.8 (median 3) and diagnostic confidence was rated at 4.7 +/- 0.5 (median 5). Interrater agreement was high (kappa = 0.85, P < 0.001). Three-dimensional T1-BB-MRI displayed bilateral findings in 50% of the cases, whereas only unilateral A-AION was detected in funduscopy as a possible indication for the contralateral eye at risk. Conclusions: Three-dimensional T1-BB-MRI allows accurate detection of arteritic posterior ciliary artery involvement in patients with A-AION. Further, 3D T1-BB-MRI seems to display arteritic involvement of the posterior ciliary arteries earlier than funduscopy and might, therefore, display "vision-at-risk" in patients with visual impairment and suspected giant cell arteritis but unremarkable funduscopy
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