248 research outputs found
Trends and cycles: How important are long- and short-run restictions? The case of Mexico
The document presents a test for the existence of binding long- and short-run (common trend-common cycle) restrictions in the dynamics of a set of Mexican macroeconomic variables. These restrictions are imposed in a VAR to decompose the series into their permanent and transitory components. The analysis shows that the magnitude of transitory (nominal) shocks is underestimated when such restrictions are not considered. In addition, we find that the timing and duration of recession and expansion periods are more accurately estimated when the trend-cycle decomposition is conducted with the imposition of cointegrating (long-run) and common feature (short-run) restrictions.
Efecto del gasto público sobre el gasto privado en México
Traditionally, the analysis of the impact of public expenditure on private expenditure has been performed via graphical evaluations and simple econometric exercises. In this document we present a detailed econometric analysis of the relationship between said variables. In particular, we evaluate the existence of a crowding out effect of public consumption and investment on private consumption and investment for the period 1980:I - 2002:II. The econometric results indicate that public investment crowds out private investment in the short-run but complements it in the long-run. In the case of private consumption we find statistically significant evidence of crowding out during the period of analysis.
Sincronización del empleo manufacturero en México y Estados Unidos
It is evident that there exists a high degree of economic interdependence betweenMexico and the United States at the aggregate level. It is not clear, however, that this relationship holds for individual economic sectors. In this document we investigate the existence of common movements, at trend and cyclical horizons, in the behavior of employment in the manufacturing sector for both countries.We find that employment in the non-maquila manufacturing sector in Mexico exhibits a higher degree of synchronization with the manufacturing employment in the U.S. than does the maquiladora sector.We argue that these results are consistent with the theories of economic integration and specialization in production.labor markets, common cycle, common trend.
Flavor changing neutral currents with a fourth family of quarks
For a model with a fourth family of quarks, new sources of flavor changing
neutral currents are identified by confronting the unitary 4x4 quark mixing
matrix with the experimental measured values of the familiar 3x3 quark mixing
matrix. By imposing as experimental constraints the known bounds for the flavor
changing neutral currents, the largest mixing of the known quarks with the
fourth family ones is established. The predictions are: a value for |V_{tb}|
significantly different from unity, large rates for rare top decays as
t->c\gamma and t->cZ, the last one reachable at the Large Hadrion Collider, and
large rates for rare strange decays s->d\gamma and s->dg, where g stands for
the gluon field.Comment: 7 pages, one figure. Published on Physical Review
Active gravitational mass and the invariant characterization of Reissner-Nordstrom spacetime
We analyse the concept of active gravitational mass for Reissner-Nordstrom
spacetime in terms of scalar polynomial invariants and the Karlhede
classification. We show that while the Kretschmann scalar does not produce the
expected expression for the active gravitational mass, both scalar polynomial
invariants formed from the Weyl tensor, and the Cartan scalars, do.Comment: 6 pages Latex, to appear in General Relativity and Gravitatio
Quintessential Phenomena in Higher Dimensional Space Time
The higher dimensional cosmology provides a natural setting to treat, at a
classical level, the cosmological effects of vacuum energy. Here we discuss two
situations where starting with an ordinary matter field without any equation of
state we end up with a Chaplygin type of gas apparently as a consequence of
extra dimensions. In the second case we study the quintessential phenomena in
higher dimensional spacetime with the help of a Chaplygin type of matter field.
The first case suffers from the disqualification that no dimensional reduction
occurs, which is, however, rectified in the second case. Both the models show
the sought after feature of occurrence of \emph{flip} in the rate of expansion.
It is observed that with the increase of dimensions the occurrence of
\emph{flip} is delayed for both the models, more in line with current
observational demands. Interestingly we see that depending on some initial
conditions our model admits QCDM, CDM and also Phantom like evolution
within a unified framework. Our solutions are general in nature in the sense
that when the extra dimensions are switched off the known 4D model is
recovered.Comment: 17 Pages, 7 figure
Expression of USP18 and IL2RA is increased in individuals receiving latent tuberculosis treatment with isoniazid
Background. The treatment of latent tuberculosis infection (LTBI) in individuals at risk of reactivation is essential for tuberculosis control. However, blood biomarkers associated with LTBI treatment have not been identified. Methods. Blood samples from tuberculin skin test (TST) reactive individuals were collected before and after one and six months of isoniazid (INH) therapy. Peripheral mononuclear cells (PBMC) were isolated, and an in-house interferon-γ release assay (IGRA) was performed. Expression of chemokine ligand 4 (CCL4), chemokine ligand 10 (CXCL10), chemokine ligand 11 (CXCL11), interferon alpha (IFNA), radical S-adenosyl methionine domain-containing 2 (RSAD2), ubiquitin-specific peptidase 18 (USP18), interferon-induced protein 44 (IFI44), interferon-induced protein 44 like (IFI44L), interferon-induced protein tetratricopeptide repeats 1(IFIT1), and interleukin 2 receptor subunit alpha (IL2RA) mRNA levels were assessed by qPCR before, during, and after INH treatment. Results. We observed significantly lower relative abundances of USP18, IFI44L, IFNA, and IL2RA transcripts in PBMC from IGRA-positive individuals compared to levels in IGRA-negative individuals before INH therapy. Also, relative abundance of CXCL11 was significantly lower in IGRA-positive than in IGRA-negative individuals before and after one month of INH therapy. However, the relative abundance of CCL4, CXCL10, and CXCL11 mRNA was significantly decreased and that of IL2RA and USP18 significantly increased after INH therapy, regardless of the IGRA result. Our results show that USP18, IFI44L, IFIT1, and IL2RA relative abundances increased significantly, meanwhile the relative abundance of CCL4, CXCL11, and IFNA decreased significantly after six months of INH therapy in TST-positive individuals. Conclusions. Changes in the profiles of USP18, IL2RA, IFNA, CCL4, and CXCL11 expressions during INH treatment in TST-positive individuals, regardless of IGRA status, are potential tools for monitoring latent tuberculosis treatment
Experimental Tests of Factorization in Charmless Non-Leptonic Two-Body B Decays
Using a theoretical framework based on the next-to-leading order QCD-improved
effective Hamiltonian and a factorization Ansatz for the hadronic matrix
elements of the four-quark operators, we reassess branching fractions in
two-body non-leptonic decays , involving the lowest lying
light pseudoscalar and vector mesons in the standard model. Using
the sensitivity of the decay rates on the effective number of colors, , as
a criterion of theoretical predictivity, we classify all the current-current
(tree) and penguin transitions in five different classes. The recently measured
charmless two-body decays and charge conjugates) are
dominated by the -stable QCD penguins (class-IV transitions) and their
estimates are consistent with data. The measured charmless and transition ,
on the other hand, belong to the penguin (class-V) and tree (class-III)
transitions. The class-V penguin transitions are in general more difficult to
predict. We propose a number of tests of the factorization framework in terms
of the ratios of branching ratios for some selected decays
involving light hadrons and , which depend only moderately on the
form factors. We also propose a set of measurements to determine the effective
coefficients of the current-current and QCD penguin operators. The potential
impact of decays on the CKM phenomenology is emphasized by
analyzing a number of decay rates in the factorization framework.Comment: 64 pages (LaTex) including 13 figures, requires epsfig.sty; submitted
to Phys. Rev.
Self-Similarity in General Relativity \endtitle
The different kinds of self-similarity in general relativity are discussed,
with special emphasis on similarity of the ``first'' kind, corresponding to
spacetimes admitting a homothetic vector. We then survey the various classes of
self-similar solutions to Einstein's field equations and the different
mathematical approaches used in studying them. We focus mainly on spatially
homogenous and spherically symmetric self-similar solutions, emphasizing their
possible roles as asymptotic states for more general models. Perfect fluid
spherically symmetric similarity solutions have recently been completely
classified, and we discuss various astrophysical and cosmological applications
of such solutions. Finally we consider more general types of self-similar
models.Comment: TeX document, 53 page
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