111 research outputs found
Non-linearities and unit roots in G7 macroeconomic variables
We carry out a meta-analysis on the frequency of unit-roots in macroeconomic time series with a dataset covering 249 variables for the G7 countries. We use linear tests and the three popular non-linear tests (TAR, ESTAR and Markov Switching). In general, the evidence in favour of the random walk hypothesis is weaker than in previous studies. This evidence against unit roots is stronger for real and nominal asset prices. Our results show that rejection of the null of a unit root in the macro dataset is substantially higher for non-linear than linear models. Finally, the results from a Monte Carlo experiment show that rejection frequencies are very close to the nominal size of the test when the DGP is a linear unit root process. This leads us to reject the hypothesis that overfitting deterministic components explains the higher rejection frequencies of nonlinear tests
The evolution of the universe from noncompact Kaluza-Klein theory
We develope a 5D mechanism inspired in the Campbell's theorem, to explain the
(neutral scalar field governed) evolution of the universe from a initially
inflationary expansion that has a change of phase towards a decelerated
expansion and thereinafter evolves towards the present day observed celerated
(quintessential) expansion.Comment: version accepted in Eur. Phys. J.
Extra force and extra mass from noncompact Kaluza-Klein theory in a cosmological model
Using the Hamilton-Jacobi formalism, we study extra force and extra mass in a
recently introduced noncompact Kaluza-Klein cosmological model. We examine the
inertial 4D mass of the inflaton field on a 4D FRW bulk in two examples.
We find that has a geometrical origin and antigravitational effects on a
non inertial 4D bulk should be a consequence of the motion of the fifth
coordinate with respect to the 4D bulk.Comment: final version to be published in EPJ
Origin of FRW cosmology in slow-roll inflation from noncompact Kaluza-Klein theory
Using a recently introduced formalism we discuss slow-roll inflaton from
Kaluza-Klein theory without the cylinder condition. In particular, some
examples corresponding to polynomic and hyperbolic -potentials are
studied. We find that the evolution of the fifth coordinate should be
determinant for both, the evolution of the early inflationary universe and the
quantum fluctuations.Comment: (final version) to be published in EPJ
Scale invariant scalar metric fluctuations during inflation: non-perturbative formalism from a 5D vacuum
We extend to 5D an approach of a 4D non-perturbative formalism to study
scalar metric fluctuations of a 5D Riemann-flat de Sitter background metric. In
contrast with the results obtained in 4D, the spectrum of cosmological scalar
metric fluctuations during inflation can be scale invariant and the background
inflaton field can take sub-Planckian values.Comment: final version to be published in Eur. Phys. J.
Occupational choice of return migrants in Moldova
This paper analyzes the occupational choice of return migrants. Using the survey data on different aspects of migration in Moldova, we find that those who stayed illegally in the host country tend to go into wage employment on return to the home country. We also show that relatively better educated migrants tend not to be in formal employment (i.e., appear not to participate in the labor market), whereas those with relatively lower skills or who obtained a worse-than-expected outcome in the host country are more likely to be wage employed in the home country on return. We offer an economic analysis of these paradoxical results
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Gelatin Methacryloyl Bioadhesive Improves Survival and Reduces Scar Burden in a Mouse Model of Myocardial Infarction.
Background Delivery of hydrogels to the heart is a promising strategy for mitigating the detrimental impact of myocardial infarction (MI). Challenges associated with the in vivo delivery of currently available hydrogels have limited clinical translation of this technology. Gelatin methacryloyl (GelMA) bioadhesive hydrogel could address many of the limitations of available hydrogels. The goal of this proof-of-concept study was to evaluate the cardioprotective potential of GelMA in a mouse model of MI. Methods and Results The physical properties of GelMA bioadhesive hydrogel were optimized in vitro. Impact of GelMA bioadhesive hydrogel on post-MI recovery was then assessed in vivo. In 20 mice, GelMA bioadhesive hydrogel was applied to the epicardial surface of the heart at the time of experimental MI. An additional 20 mice underwent MI but received no GelMA bioadhesive hydrogel. Survival rates were compared for GelMA-treated and untreated mice. Left ventricular function was assessed 3 weeks after experimental MI with transthoracic echocardiography. Left ventricular scar burden was measured with postmortem morphometric analysis. Survival rates at 3 weeks post-MI were 89% for GelMA-treated mice and 50% for untreated mice (P=0.011). Left ventricular contractile function was better in GelMA-treated than untreated mice (fractional shortening 37% versus 26%, P<0.001). Average scar burden in GelMA-treated mice was lower than in untreated mice (6% versus 22%, P=0.017). Conclusions Epicardial GelMA bioadhesive application at the time of experimental MI was performed safely and was associated with significantly improved post-MI survival compared with control animals. In addition, GelMA treatment was associated with significantly better preservation of left ventricular function and reduced scar burden
Seminal magnetic fields from Inflato-electromagnetic Inflation
We extend some previous attempts to explain the origin and evolution of
primordial magnetic fields during inflation induced from a 5D vacuum. We show
that the usual quantum fluctuations of a generalized 5D electromagnetic field
cannot provide us with the desired magnetic seeds. We show that special fields
without propagation on the extra non-compact dimension are needed to arrive to
appreciable magnetic strengths. We also identify a new magnetic tensor field
in this kind of extra dimensional theories. Our results are in very
good agreement with observational requirements, in particular from TeV Blazars
and CMB radiation limits we obtain that primordial cosmological magnetic fields
should be close scale invariance.Comment: Improved version. arXiv admin note: text overlap with arXiv:1007.3891
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