113 research outputs found
New estimates of the hybrid US Phillips curve
This paper examines the validity of Rudd and Whelanâs (2006) critiques of Gali and Gertlerâs (1999) hybrid Phillips curve (HYPC) by re-estimating the HYPC using full information maximum likelihood (FIML). We also estimate HYPC with the constraint that the weights for the sum of forward looking and backward looking expectations should be unity. Our results support Rudd and Whelanâs conclusion that the weight for forward looking expectations is insignificant.New Keynesian Phillips Curve, Price Rigidities, FIML Estimation
New estimates of the hybrid US Phillips curve
This paper examines the validity of Rudd and Whelanâs (2006) critiques of Gali and Gertlerâs (1999) hybrid Phillips curve (HYPC) by re-estimating the HYPC using full information maximum likelihood (FIML). We also estimate HYPC with the constraint that the weights for the sum of forward looking and backward looking expectations should be unity. Our results support Rudd and Whelanâs conclusion that the weight for forward looking expectations is insignificant
Spectral Clustering: An Empirical Study of Approximation Algorithms and its Application to the Attrition Problem
Clustering is the problem of separating a set of objects into groups (called clusters) so that objects within the same cluster are more similar to each other than to those in different clusters. Spectral clustering is a now well-known method for clustering which utilizes the spectrum of the data similarity matrix to perform this separation. Since the method relies on solving an eigenvector problem, it is computationally expensive for large datasets. To overcome this constraint, approximation methods have been developed which aim to reduce running time while maintaining accurate classification. In this article, we summarize and experimentally evaluate several approximation methods for spectral clustering. From an applications standpoint, we employ spectral clustering to solve the so-called attrition problem, where one aims to identify from a set of employees those who are likely to voluntarily leave the company from those who are not. Our study sheds light on the empirical performance of existing approximate spectral clustering methods and shows the applicability of these methods in an important business optimization related problem
New estimates of the hybrid US Phillips curve
This paper examines the validity of Rudd and Whelanâs (2006) critiques of Gali and Gertlerâs (1999) hybrid Phillips curve (HYPC) by re-estimating the HYPC using full information maximum likelihood (FIML). We also estimate HYPC with the constraint that the weights for the sum of forward looking and backward looking expectations should be unity. Our results support Rudd and Whelanâs conclusion that the weight for forward looking expectations is insignificant
High energy photon-neutrino elastic scattering
The one-loop helicity amplitudes for the elastic scattering process
in the Standard Model are computed at high center of
mass energies. A general decomposition of the amplitudes is utilized to
investigate the validity of some of the key features of our results. In the
center of mass, where , the cross section grows roughly as
to near the threshold for -boson production, .
Although suppressed at low energies, we find that the elastic cross section
exceeds the cross section for when
GeV. We demonstrate that the scattered photons are circularly polarized and the
net value of the polarization is non-zero. Astrophysical implications of high
energy photon-neutrino scattering are discussed.Comment: 9 pages, 7 figures, RevTeX
The Amplitude in an External Homogeneous Electromagnetic Field
Neutrino-photon interactions in the presence of an external homogeneous
constant electromagnetic field are studied. The amplitude is
calculated in an electromagnetic field of the general type, when the two field
invariants are nonzero.Comment: 7 pages, 1 figur
MEKK2 mediates aberrant ERK activation in neurofibromatosis type I
Neurofibromatosis type I (NF1) is characterized by prominent skeletal manifestations caused by NF1 loss. While inhibitors of the ERK activating kinases MEK1/2 are promising as a means to treat NF1, the broad blockade of the ERK pathway produced by this strategy is potentially associated with therapy limiting toxicities. Here, we have sought targets offering a more narrow inhibition of ERK activation downstream of NF1 loss in the skeleton, finding that MEKK2 is a novel component of a noncanonical ERK pathway in osteoblasts that mediates aberrant ERK activation after NF1 loss. Accordingly, despite mice with conditional deletion of Nf1 in mature osteoblasts (Nf1(fl/fl);Dmp1-Cre) and Mekk2(-/-) each displaying skeletal defects, Nf1(fl/fl);Mekk2(-/-);Dmp1-Cre mice show an amelioration of NF1-associated phenotypes. We also provide proof-of-principle that FDA-approved inhibitors with activity against MEKK2 can ameliorate NF1 skeletal pathology. Thus, MEKK2 functions as a MAP3K in the ERK pathway in osteoblasts, offering a potential new therapeutic strategy for the treatment of NF1
High-energy neutrino conversion and the lepton asymmetry in the universe
We study matter effects on oscillations of high-energy neutrinos in the
Universe. Substantial effect can be produced by scattering of the neutrinos
from cosmological sources (z\gta 1) on the relic neutrino background,
provided that the latter has large CP-asymmetry: \eta\equiv
(n_\nu-n_{\bar{\nu}})/n_\gamma\gta 1, where , and
are the concentrations of neutrinos, antineutrinos and photons. We
consider in details the dynamics of conversion in the expanding neutrino
background. Applications are given to the diffuse fluxes of neutrinos from
GRBs, AGN, and the decay of super-heavy relics. We find that the vacuum
oscillation probability can be modified by and in extreme cases
allowed by present bounds on the effect can reach .
Signatures of matter effects would consist (i) for both active-active and
active-sterile conversion, in a deviation of the numbers of events produced in
a detector by neutrinos of different flavours,
, and of their ratios from the values given by
vacuum oscillations; such deviations can reach , (ii) for
active-sterile conversion, in a characteristic energy dependence of the ratios
. Searches for these matter
effects will probe large CP and lepton asymmetries in the universe.Comment: 32 pages, RevTeX, 16 figures. Substantial changes in the treatment of
conversion effects in the relic neutrino background and of active-active
oscillations of high-energy neutrinos. Figures and references added;
conclusions partially modifie
Reduction of the two-body dynamics to a one-body description in classical electrodynamics
We discuss the mapping of the conservative part of two-body electrodynamics
onto that of a test charged particle moving in some external electromagnetic
field, taking into account recoil effects and relativistic corrections up to
second post-Coulombian order. Unlike the results recently obtained in general
relativity, we find that in classical electrodynamics it is not possible to
implement the matching without introducing external parameters in the effective
electromagnetic field. Relaxing the assumption that the effective test particle
moves in a flat spacetime provides a feasible way out.Comment: 20 pages, revtex; minor change
- âŠ