2,043 research outputs found
A note on the expectations hypothesis at the founding of the Fed
One of the most influential tests of the expectations hypothesis is Mankiw and Miron (1986), who found that the spread between the long-term and short-term rates provided predictive power for the short-term rate before the Fed's founding but not after. They suggested that the failure of the expectations hypothesis after the Fed's founding was due to the Fed's practice of smoothing short-term interest rates. We show that their finding that the expectations hypothesis fares better prior to the Fed's founding is due to the fact that the test they employ tends to generate results that are more favorable to the expectations hypothesis during periods when there is extreme volatility in the short-term rate. (Earlier version titled: The expectations theory and the founding of the Fed: another look at the evidence)Interest rates ; Rational expectations (Economic theory) ; Federal Reserve System - History
Virtual Segre and Verlinde numbers of projective surfaces
Recently, Marian-Oprea-Pandharipande established (a generalization of) Lehn's
conjecture for Segre numbers associated to Hilbert schemes of points on
surfaces. Extending work of Johnson, they provided a conjectural correspondence
between Segre and Verlinde numbers. For surfaces with holomorphic 2-form, we
propose conjectural generalizations of their results to moduli spaces of stable
sheaves of any rank.
Using Mochizuki's formula, we derive a universal function which expresses
virtual Segre and Verlinde numbers of surfaces with holomorphic 2-form in terms
of Seiberg-Witten invariants and intersection numbers on products of Hilbert
schemes of points. We prove that certain canonical virtual Segre and Verlinde
numbers of general type surfaces are topological invariants and we verify our
conjectures in examples.
The power series in our conjectures are algebraic functions, for which we
find expressions in several cases and which are permuted under certain Galois
actions. Our conjectures imply an algebraic analog of the Mari\~{n}o-Moore
conjecture for higher rank Donaldson invariants. For ranks and , we
obtain new expressions for Donaldson invariants in terms of Seiberg-Witten
invariants.Comment: Minor corrections. 38 page
You Help Me, He Helps You: Dispute Systems Design in the Sharing Economy
Kulp and Kool discuss the potential for dispute resolution schemes in a sharing economy, one they argue involves a more efficient use of resources. The sharing economy is at the nexus of fast-paced technology that connects people to previously inaccessible resources to increase local consumption. Kulp and Kool argue that such sharing economies maximize the benefits of ownership by leveraging goods and services into a resource generator allowing increased access to goods and services at a lower-than-market rate. This unique market structure requires a distinct set of laws to address the unique relationships involved, and this Article explores how attorneys can best assist in managing conflicts in a sharing economy
Verlinde formulae on complex surfaces: K-theoretic invariants
We conjecture a Verlinde type formula for the moduli space of Higgs sheaves
on a surface with a holomorphic 2-form. The conjecture specializes to a
Verlinde formula for the moduli space of sheaves. Our formula interpolates
between -theoretic Donaldson invariants studied by the first named author
and Nakajima-Yoshioka and -theoretic Vafa-Witten invariants introduced by
Thomas and also studied by the first and second named authors. We verify our
conjectures in many examples (e.g. on K3 surfaces).Comment: Published version. 37 page
Online tracking: Questioning the power of informed consent
Online tracking technologies have raised considerable concerns regarding privacy and the protection of personal data of users. In order to help users to regain control over their personal data, Europe has amended its ePrivacy directive towards an opt-in regime. There are however many open questions concerning its implementation, especially regarding the issue of informed consent. This paper explores how the new legal situation impacts on behavioral advertising practices via the storing and reading of cookies in the Netherlands. The results show that the majority of the surveyed parties involved in behavioural advertising do not inform users about the storing of cookies or the purposes of data processing of the subsequently obtained data, neither do they have obtained users' consent for the storage of cookies. We also found that the majority of users lack the skills and knowledge how to handle cookies. These findings critically question the wisdom of the informed consent regime which lies currently at the heart of Europe's ePrivacy directive. --Online behavioural advertising,profiling,cookies,informed consent,Do Not Track,ePrivacy Directive
Approaches for estimating unsaturated soil hydraulic conductivities at various bulk densities with the extended Mualem-van Genuchten model
The Mualem-van Genuchten model has been widely used for estimating unsaturated soil hydraulic conductivity (Ku) from measured saturated hydraulic conductivity (Ks) and fitted water retention curve (WRC) parameters. Soil bulk density (Ïb) variations affect the accuracy of Ku estimates. In this study, we extend the Mualem-van Genuchten model to account for the Ïb effect with Ïb-related WRC and Ks models. We apply two functions (A and B) that relate the van Genuchten WRC model to Ïb and two models (1 and 2) that estimate Ks with various Ïb. By combining the Ïb-related WRC functions and Ks models, we develop four integrated approaches (i.e., A1, A2, B1, and B2) for estimating Ku at various Ïb. Kumeasurements made on five soils with various textures and Ïb are used to evaluate the accuracy of the four approaches. The results show that all approaches produce reasonable Ku estimates, with average root mean square errors (RMSEs) less than 0.35 (expressed in dimensionless unit because logarithmic Ku values are used). Approach A2, with an average RMSE of 0.25, agrees better with Ku measurements than does Approach A1 that has an average RMSE of 0.28. This is because Model 2 accounts for the WRC shape effect near saturation. Approaches A1 and A2 give more accurate Ku estimates than do Approaches B1 and B2 which both have average RMSEs of 0.35, because Function A performs better in estimating WRCs than does Function B. The proposed approaches could be incorporated into simulation models for improved prediction of water, solute, and gas transport in soils
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