4,250 research outputs found
Stock returns, term structure, inflation and real activity: An international perspective
This paper analyses the empirical interdependences among asset returns, real activity and inflation from a multicountry and international point of view. We find that nominal stock returns are significantly related to inflation only in the US, that the US term structure of interest rates predicts both domestic and foreign inflation rates while foreign term structures do not have this predictive power and that innovations in inflation and exchange rates induce insignificant responses of real and financial variables. An interpretation of the dynamics and some policy implications of the results are provided.Transmission, business cycles, international stock returns, financial markets
Large-signal stability conditions for semi-quasi-Z-source inverters: switched and averaged models
The recently introduced semi-quasi-Z-source in- verter can be interpreted as
a DC-DC converter whose input- output voltage gain may take any value between
minus infinity and 1 depending on the applied duty cycle. In order to generate
a sinusoidal voltage waveform at the output of this converter, a time-varying
duty cycle needs to be applied. Application of a time-varying duty cycle that
produces large-signal behavior requires careful consideration of stability
issues. This paper provides stability results for both the large-signal
averaged and the switched models of the semi-quasi-Z-source inverter operating
in continuous conduction mode. We show that if the load is linear and purely
resistive then the boundedness and ultimate boundedness of the state
trajectories is guaranteed provided some reasonable operation conditions are
ensured. These conditions amount to keeping the duty cycle away from the
extreme values 0 or 1 (averaged and switched models), and limiting the maximum
PWM switching period (switched model). The results obtained can be used to give
theoretical justification to the inverter operation strategy recently proposed
by Cao et al. in [1].Comment: Submitted to the IEEE Conf. on Decision and Control, Florence, Italy,
201
Entanglement criteria for microscopic-macroscopic systems
We discuss the conclusions that can be drawn on a recent experimental
micro-macro entanglement test [F. De Martini, F. Sciarrino, and C. Vitelli,
Phys. Rev. Lett. 100, 253601 (2008). The system under investigation is
generated through optical parametric amplification of one photon belonging to
an entangled pair. The adopted entanglement criterion makes it possible to
infer the presence of entanglement before losses, that occur on the macrostate,
under a specific assumption. In particular, an a priori knowledge of the system
that generates the micro-macro pair is necessary to exclude a class of
separable states that can reproduce the obtained experimental results. Finally,
we discuss the feasibility of a micro-macro "genuine" entanglement test on the
analyzed system by considering different strategies, which show that in
principle a fraction epsilon, proportional to the number of photons that
survive the lossy process, of the original entanglement persists in any losses
regime.Comment: 11 pages, 10 figure
Identifying hadronic charmonium decays in hadron colliders
Identification of charmonium states at hadron colliders has mostly been
limited to leptonic decays of the J/{\psi}. In this paper we present and
algorithm to identify hadronic decays of charmonium states (J/{\psi},
{\psi}(2S), \chi_{c0,1,2}) which make up the large majority of all decays. The
algorithm is able to identify hadronic decays with an efficiency of
36\% while suppressing a background of quark and gluon jets by a factor 100.Comment: 8 pages, 2 figures, submitted to SciPos
Long-term radiographic and clinical-functional outcomes of isolated, displaced, closed talar neck and body fractures treated by ORIF: the timing of surgical management
Background: The main purpose of this retrospective case series study was to evaluate long-term radiographic and clinical outcomes of a consecutive series of patients diagnosed with isolated, displaced, closed talar neck or body fractures treated by open reduction and internal fixation (ORIF). Secondly, the aim was to verify the influence of the location of talar fractures on the outcomes, the prognostic value of the Hawkins sign, whether operative delays promote avascular necrosis (AVN) and if the fractures require emergent surgical management.
Methods: From January 2007 to December 2012, at our institution, 31 patients underwent ORIF through the use of screws. On the basis of Inokuchi criteria, the injuries were divided between neck and body fractures, which were classified according to Hawkins and Sneppen, respectively. The patients included were divided into two groups in relation to fracture location and complexity. Radiographic assessment focused on reduction quality, bone healing, the Hawkins sign and post-traumatic arthritis (PTA) development. For the clinical evaluation, clinical-functional scores (AOFAS Ankle-Hindfoot Score; MFS; FFI-17; SF-36) and VAS were determined, and statistical analysis was performed.
Results: 27 patients, 19 males and 8 females, mean age 38.3 years, were included with an average follow-up period of 83.2 months (range 49\u2013119). There were 9 neck and 19 body fractures; their reduction was anatomical or nearly anatomical in 22 cases, and all reached radiographic consolidation after a mean period of 3.4 months (range 1.7\u20137). The Hawkins sign was observed in 9 cases, in which necrosis did not develop. With a 0\u201311 day surgical timing interval, more than 60% of the patients obtained good or fair results with different scores, while 18 (66.7%) were completely satisfied (VAS: 9\u201310). The early complications included malunions (21.4%) and wound problems (25%); the late complications involved AVN (25%) and PTA (78.6%).
Conclusions: Despite a high rate of long-term complications, satisfactory clinical results were achieved. Talar fracture location did not influence the outcomes, the Hawkins sign was confirmed as a positive prognostic factor, and operation timing did not influence AVN development. Hence, these injuries do not require emergent surgical management by ORIF
Perturbative estimates for the one-phase Stefan Problem
We provide perturbative estimates for the one-phase Stefan free boundary
problem and obtain the regularity of flat free boundaries via a linearization
technique in the spirit of the elliptic counterpart established by the first
author
First deep underground observation of rotational signals from an earthquake at teleseismic distance using a large ring laser gyroscope
Recent advances in large ring laser gyroscopes (RLG) technologies opened the
possibility to observe rotations of the ground with sensitivities up to
over the frequency band of seismological interest
(0.01-1Hz), thus opening the way to a new geophysical discipline, i.e.
rotational seismology. A measure of rotations in seismology is of fundamental
interest for (a) the determination of all the six degrees of freedom that
characterize a rigid body motion, and (b) the quantitative estimate of the
rotational motions contaminating ground translation measurements obtained from
standard seismometers. Within this framework, this paper presents and describes
GINGERino, a new large observatory-class RLG located in Gran Sasso underground
laboratory (LNGS), one national laboratories of the INFN (Istituto Nazionale di
Fisica Nucleare). We also report unprecedented observations and analyses of the
roto-translational signals from a tele-seismic event observed in such a deep
underground environment
Parameter clustering in Bayesian functional PCA of neuroscientific data
The extraordinary advancements in neuroscientific technology for brain recordings over the last decades have led to increasingly complex spatiotemporal data sets. To reduce oversimplifications, new models have been developed to be able to identify meaningful patterns and new insights within a highly demanding data environment. To this extent, we propose a new model called parameter clustering functional principal component analysis (PCl-fPCA) that merges ideas from functional data analysis and Bayesian nonparametrics to obtain a flexible and computationally feasible signal reconstruction and exploration of spatiotemporal neuroscientific data. In particular, we use a Dirichlet process Gaussian mixture model to cluster functional principal component scores within the standard Bayesian functional PCA framework. This approach captures the spatial dependence structure among smoothed time series (curves) and its interaction with the time domain without imposing a prior spatial structure on the data. Moreover, by moving the mixture from data to functional principal component scores, we obtain a more general clustering procedure, thus allowing a higher level of intricate insight and understanding of the data. We present results from a simulation study showing improvements in curve and correlation reconstruction compared with different Bayesian and frequentist fPCA models and we apply our method to functional magnetic resonance imaging and electroencephalogram data analyses providing a rich exploration of the spatiotemporal dependence in brain time series.Publisher PDFPeer reviewe
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