740 research outputs found
Beyond the crisis: revisiting emerging Europe’s growth model
Focusing on the nexus between economic growth and the buildup of external vulnerabilities, this paper provides a systematic account of different growth strategies followed in Central and Eastern Europe in 2000-08 and then uses this growth diagnostics to derive implications for a post-crisis recovery. The main findings point to three policy lessons for improving growth sustainability. First, greater reliance on tradable sectors should be the cornerstone of a future growth model. Second, enhancing domestic sources of bank credit funding would contribute to the mitigation of external vulnerabilities and make the domestic financial system more resilient to global financial shocks. Third, prudential and macroeconomic policies will have to be more proactive in managing capital inflows, including funneling these inflows into investment in export-oriented industries.sustainable economic growth, sources of growth, external vulnerabilities
Neutrinos and Gamma Rays from Photomeson Processes in Gamma Ray Bursts
Acceleration of high-energy hadrons in GRB blast waves will be established if
high-energy neutrinos are detected from GRBs. Recent calculations of photomeson
neutrino production are reviewed, and new calculations of high-energy neutrinos
and the accompanying hadronic cascade radiation are presented. If hadrons are
injected in GRB blast waves with an energy corresponding to the measured hard
X-ray/soft gamma-ray emission, then only the most powerful bursts at fluence
levels >~ 3e-4 erg cm^{-2} offer a realistic prospect for detection of muon
neutrinos. Detection of high-energy neutrinos are likely if GRB blast waves
have large baryon loads and Doppler factors <~ 200. Significant limitations on
the hadronic baryon loading and the number of expected neutrinos are imposed by
the fluxes from pair-photon cascades initiated in the same processes that
produce neutrinos.Comment: 4 pages, 2 figures, in 2003 Santa Fe Conference on GRB
On Hadronic Models for the Anomalous -ray Emission Component in GRB 941017
Gonz\'alez et al. (2003) have reported the discovery of an anomalous
radiation component from ~ 1 -- 200 MeV in GRB 941017. This component varies
independently of and contains >~ 3 times the energy found in the prompt ~ 50
keV -- 1 MeV radiation component that is well described by the relativistic
synchrotron-shock model. Acceleration of hadrons to very high energies by GRBs
could give rise to a separate emission component. Two models, both involving
acceleration of ultra-high energy cosmic rays with subsequent photomeson
interactions, are considered. The first involves a pair-photon cascade
initiated by photohadronic processes in the GRB blast wave. Calculations
indicate that the cascade produces a spectrum that is too soft to explain the
observations. A second model is proposed where photopion interactions in the
GRB blast-wave shell give rise to an escaping collimated neutron beam. The
outflowing neutrons undergo further photopion interactions to produce a beam of
hyper-relativistic electrons that can lose most of their energy during a
fraction of a gyroperiod in the Gauss-strength magnetic fields found in the
circumburst medium. This secondary electron beam produces a hard synchrotron
radiation spectrum that could explain the anomalous component in GRB 941017.Comment: 5 pages, 1 figure, in 2003 Santa Fe Conference on GRB
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