42,544 research outputs found
Time series behavior of the short-term real interest rates in industrial countries
With quarterly data of a sample period starting from 1973, the conventional unit root tests reject the null of nonstationarity in favor of the alternative of linear stationarity for short-term real interest rates (RIRs) of non-European industrial countries. There is evidence of nonlinearities in many European countries’ RIRs, most of which appear to be stationary exponential smooth transition autoregressive processes.Real interest rates; Unit root; Nonlinear stationarity
Tolerating Correlated Failures in Massively Parallel Stream Processing Engines
Fault-tolerance techniques for stream processing engines can be categorized
into passive and active approaches. A typical passive approach periodically
checkpoints a processing task's runtime states and can recover a failed task by
restoring its runtime state using its latest checkpoint. On the other hand, an
active approach usually employs backup nodes to run replicated tasks. Upon
failure, the active replica can take over the processing of the failed task
with minimal latency. However, both approaches have their own inadequacies in
Massively Parallel Stream Processing Engines (MPSPE). The passive approach
incurs a long recovery latency especially when a number of correlated nodes
fail simultaneously, while the active approach requires extra replication
resources. In this paper, we propose a new fault-tolerance framework, which is
Passive and Partially Active (PPA). In a PPA scheme, the passive approach is
applied to all tasks while only a selected set of tasks will be actively
replicated. The number of actively replicated tasks depends on the available
resources. If tasks without active replicas fail, tentative outputs will be
generated before the completion of the recovery process. We also propose
effective and efficient algorithms to optimize a partially active replication
plan to maximize the quality of tentative outputs. We implemented PPA on top of
Storm, an open-source MPSPE and conducted extensive experiments using both real
and synthetic datasets to verify the effectiveness of our approach
Interaction Between Supernova Remnant G22.7-0.2 And The Ambient Molecular Clouds
We have carried out 12CO (J=1-0 and 2-1), 13CO (J=1-0), and C18O (J=1-0)
observations in the direction of the supernova remnant (SNR) G22.7-0.2. A
filamentary molecular gas structure, which is likely part of a larger molecular
complex with VLSR~75-79 km/s, is detected and is found to surround the southern
boundary of the remnant. In particular, the high-velocity wing (77-110 km/s) in
the 12CO (J=1-0 and J=2-1) emission shows convincing evidence of the
interaction between SNR G22.7-0.2 and the 75-79 km/s molecular clouds (MCs).
Spectra with redshifted profiles, a signature of shocked molecular gas, are
seen in the southeastern boundary of the remnant. The association between the
remnant and the 77 km/s MCs places the remnant at the near distance of 4.0-4.8
kpc, which agrees with a location on the Scutum-Crux arm. We suggest that SNR
G22.7-0.2, SNR W41, and HII region G022.760-0.485 are at the same distance and
are associated with GMC G23.0-0.4.Comment: 9 pages, 9 figures, 3 tables, accepted for publication in Ap
Evolutionary multiplayer games on graphs with edge diversity
Evolutionary game dynamics in structured populations has been extensively
explored in past decades. However, most previous studies assume that payoffs of
individuals are fully determined by the strategic behaviors of interacting
parties and social ties between them only serve as the indicator of the
existence of interactions. This assumption neglects important information
carried by inter-personal social ties such as genetic similarity, geographic
proximity, and social closeness, which may crucially affect the outcome of
interactions. To model these situations, we present a framework of evolutionary
multiplayer games on graphs with edge diversity, where different types of edges
describe diverse social ties. Strategic behaviors together with social ties
determine the resulting payoffs of interactants. Under weak selection, we
provide a general formula to predict the success of one behavior over the
other. We apply this formula to various examples which cannot be dealt with
using previous models, including the division of labor and relationship- or
edge-dependent games. We find that labor division facilitates collective
cooperation by decomposing a many-player game into several games of smaller
sizes. The evolutionary process based on relationship-dependent games can be
approximated by interactions under a transformed and unified game. Our work
stresses the importance of social ties and provides effective methods to reduce
the calculating complexity in analyzing the evolution of realistic systems.Comment: 50 pages, 7 figure
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