9,484 research outputs found
Time-Response Functions of Mechanical Networks with Inerters and Causality
This paper derives the causal time-response functions of three-parameter
mechanical networks that have been reported in the literature and involve the
inerter-a two-node element in which the force-output is proportional to the
relative acceleration of its end-nodes. This two-terminal device is the
mechanical analogue of the capacitor in a force-current/velocity-voltage
analogy. The paper shows that all frequency-response functions that exhibit
singularities along the real frequency axis need to be enhanced with the
addition of a Dirac delta function or with its derivative depending on the
strength of the singularity. In this way the real and imaginary parts of the
enhanced frequency response functions are Hilbert pairs; therefore, yielding a
causal time-response function in the time domain. The integral representation
of the output signals offers an attractive computational alternative given that
the constitutive equations of the three-parameter networks examined herein
involve the third derivative of the nodal displacement which may challenge the
numerical accuracy of a state-space formulation when the input signal is only
available in digital form as in the case of recorded seismic accelerograms
Seignorage and Capital Taxation: Tax Competition Revisited
We re-examine the standard view that capital taxes are too low when capital is mobile across tax jurisdictions. We do so by emphasising a previously neglected implication of non-cooperative capital tax setting in a world with national currencies. Namely, capital taxes also affect foreign seignorage. This horizontal externality may lead, ceteris paribus, to too high national capital taxes, and may more than o set the usual effects of tax competition. In this case, and contrary to conventional wisdom, national capital taxes will be too high. Conditions under which the latter is indeed the case are derived and discussed.Tax Competition, Seignorage.
Administrative Bureaus with Standard Operating Procedures
We investigate the terms of exchange between the legislative branch of the government and an administrative bureau with standard operating procedures. An administrative bureau is a not-for-profit public organisation responsible for the production of a non-marketable good. Such a bureau is tax-financed and the budget appropriations can be linked directly to a verifiable measure of the agency's performance. Also, the tax-financed transfer must not be less than the monetary cost of running the public agency. When standard operating procedures are central to the workings of the bureau, the agency is unencumbered by moral hazard. Yet, such agency is likely to have superior information over its production technology relative to the legislature. In such an information environment, we focus on how the legislature could minimise its welfare losses. Our results come in striking contrast to those in the literature on bureaucracies and to the received adverse selection findings. In a setting where the agency can be either of two cost-types, the principal finds it optimal in most cases to distort the production performance of the beureau regardless of its cost-type. Also the distortions are not of the same direction.bureaucracy, non profit organisations, adverse selection
Complementarities and Macroeconomics: Poisson Games
In many situations in macroeconomics strategic complementarities arise, and agents face a coordination problem. An important issue, from both a theoretical and a policy perspective, is equilibrium uniqueness. We contribute to this literature by focusing on the macroeconomic aspect of the problem: the number of potential innovators, speculators e.t.c. is large. In particular, we follow Myerson (1998, 2000) that in large games âa more realistic model should admit some uncertainty about the number of players in the gameâ. In more detail, we model the coordination problem as a Poisson game, and investigate the conditions under which unique equilibrium selection is obtained.Strategic Complementarities, Coordination Games, Poisson Games, Currency Crises, Innovation.
Which Democracies Pay Higher Wages?*
The labor share of income varies markedly across the set of democracies. A model of the political process, situated in a simple macroeconomic environment is analyzed in which the cause of this variation is linked to differences in the form of democracy - in particular the adoption of a presidential or parliamentary system. Presidential regimes are associated with lower taxation but lower wages. Robust evidence for the negative impact of a presidential system on the labor share is obtained using a Bayesian Model Averaging approach. Evidence is also provided that this is due to lower taxation.Fertility; Economic growth; Health expenditures
Probing Transverse-Momentum Dependent Evolution With Groomed Jets
We propose an observable which involves measuring the properties (transverse
momentum and energy fraction ) of an identified hadron inside
a groomed jet. The jet is identified with an anti-kT/CA algorithm and is
groomed by implementing the modified mass drop procedure with an energy cut-off
parameter . The transverse momentum of the hadron inside the jet is
measured with respect to the groomed jet axis. We obtain a factorization
theorem in the framework of Soft Collinear Effective Theory (SCET), to define a
Transverse Momentum Dependent Fragmenting Jet Function (TMDFJF). The TMDFJF is
factorized into collinear and collinear soft modes by matching onto SCET.
We resum large logarithms in , where is the ungroomed jet
energy, to NLL accuracy and apply this formalism for computing the shape of the
distribution of a pion produced in an collision. We
observe that the introduction of grooming makes this observable insensitive to
non-global logarithms and particularly sensitive to non-perturbative physics of
the transverse momentum dependent evolution at low values of ,
which can be probed in the variation of the cut-off parameter of the
groomer. We discuss how this observable can be used to distinguish between
non-perturbative models that describe universal TMD evolution and provide a
window into the three dimensional structure of hadrons.Comment: 23 pages, 4 figure
Jet Shapes in Dijet Events at the LHC in SCET
We consider the class of jet shapes known as angularities in dijet production
at hadron colliders. These angularities are modified from the original
definitions in e+e- collisions to be boost invariant along the beam axis. These
shapes apply to the constituents of jets defined with respect to either
k_T-type (anti-k_T, C/A, and k_T) algorithms and cone-type algorithms. We
present an SCET factorization formula and calculate the ingredients needed to
achieve next-to-leading-log (NLL) accuracy in kinematic regions where
non-global logarithms are not large. The factorization formula involves
previously unstudied "unmeasured beam functions," which are present for finite
rapidity cuts around the beams. We derive relations between the jet functions
and the shape-dependent part of the soft function that appear in the factorized
cross section and those previously calculated for e+e- collisions, and present
the calculation of the non-trivial, color-connected part of the soft-function
to O(\alpha_s). This latter part of the soft function is universal in the sense
that it applies to any experimental setup with an out-of-jet p_T veto and
rapidity cuts together with two tagged jets and it is independent of the choice
of jet (sub-)structure measurement. In addition, we implement the recently
introduced soft-collinear refactorization to resum logarithms of the jet size,
valid in the region of non-enhanced non-global logarithm effects. While our
results are valid for all 2 \to 2 channels, we compute explicitly for the qq'
\to qq' channel the color-flow matrices and plot the NLL resummed differential
dijet cross section as an explicit example, which shows that the normalization
and scale uncertainty is reduced when the soft function is refactorized. For
this channel, we also plot the jet size R dependence, the p_T^{\rm cut}
dependence, and the dependence on the angularity parameter a.Comment: 41 pages, 4 figure
Interface solitons in two-dimensional photonic lattices
We analyze localization of light at the interface separating square and
hexagonal photonic lattices, as recently realized experimentally in
two-dimensional laser-written waveguide arrays in silica glass with
self-focusing nonlinearity [A. Szameit {\em et al.}, Opt. Lett. {\bf 33}, 663
(2008)]. We reveal the conditions for the existence of {\em linear} and {\em
nonlinear} surface states substantially influenced by the lattice topology, and
study the effect of the different symmetries and couplings on the stability of
two-dimensional interface solitons.Comment: 3 pages, 4 figures, submitted to Opt. Let
Indeterminacy, intergenerational redistribution, endogenous longevity and human capital accumulation
This paper sets up an OLG economy with endogenous life expectancy to study how fiscal policy that redistributes between generations can open the door to sunspot equilibria. Agents invest independently in their own human capital, produce and consume output, and receive a pension upon retirement. The model produces an expectations coordination problem that can explain significant differences in growth paths followed by otherwise identical countries. In particular, we show that our economy may be characterised by local indeterminacy of dynamic equilibria, and hence feature fluctuations which are driven by extrinsic uncertainty.Endogenous Longevity, Human Capital, Intergenerational Redistribution, Local Indeterminacy, Sunspots.
Quantum Zeno effect by indirect measurement: The effect of the detector
We study the quantum Zeno effect in the case of indirect measurement, where
the detector does not interact directly with the unstable system. Expanding on
the model of Koshino and Shimizu [Phys. Rev. Lett., 92, 030401, (2004)] we
consider a realistic Hamiltonian for the detector with a finite bandwidth. We
also take explicitly into account the position, the dimensions and the
uncertainty in the measurement of the detector. Our results show that the
quantum Zeno effect is not expected to occur, except for the unphysical case
where the detector and the unstable system overlap.Comment: 4 pages, 4 figure
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