Las subidas en los precios de los alimentos y las materias primas: la importancia de los factores financieros y monetarios

Las subidas en los precios de los alimentos y las materias primas tienen consecuencias de gran relevancia. En este ARI se exploran las posibles causas, y se centra en la interrelación de este fenómeno con factores financieros y monetarios. La subida de los precios de las materias primas es un fenómeno complejo, en el cual podemos destacar como causas principales la demanda de los países de Asia emergente y la incidencia de factores financieros y monetarios. Es necesario analizar el fenómeno de las subidas de los precios de los alimentos conjuntamente con los del resto de materias primas, al existir evoluciones comunes y posibles causas comunes. Se destaca la importancia del contexto financiero internacional, anómalo por las turbulencias financieras y la crisis inmobiliaria, los bajos niveles de tipos de interés reales internacionales y la incertidumbre sobre la inflación mundial y tipos de cambio, que han motivado una fuerte “migración de la liquidez” internacional hacia las materias primas. No obstante, sectorialmente tampoco se debe obviar la incidencia de la demanda de biocombustibles, de políticas comerciales de restricción a la exportación y de una moderada desaceleración en la oferta de alimentos, que por otra parte sería prematuro calificar de estructural

Detection of 75+ pulsation frequencies in the δ Scuti star FG Virginis

Extensive photometric multisite campaigns of the δ Scuti variable FG Vir are presented. For the years 2003 and 2004, 926 h of photometry at the millimag precision level were obtained. The combinations with earlier campaigns lead to excellent frequency resolution and high signal/noise. A multifrequency analysis yields 79 frequencies. This represents a new record for this type of star. The modes discovered earlier were confirmed. Pulsation occurs over a wide frequency band from 5.7 to 44.3 c/d with amplitudes of 0.2 mmag or larger. Within this wide band the frequencies are not distributed at random, but tend to cluster in groups. A similar feature is seen in the power spectrum of the residuals after 79 frequencies are prewhitened. This indicates that many additional modes are excited. The interpretation is supported by a histogram of the photometric amplitudes, which shows an increase of modes with small amplitudes. The old question of the "missing modes" may be answered now: the large number of detected frequencies as well as the large number of additional frequencies suggested by the power spectrum of the residuals confirms the theoretical prediction of a large number of excited modes. FG Vir shows a number of frequency combinations of the dominant mode at 12.7162 c/d (m = 0) with other modes of relatively high photometric amplitudes. The amplitudes of the frequency sums are higher than those of the differences. A second mode (20.2878 c/d) also shows combinations. This mode of azimuthal order m = -1 is coupled with two other modes of m = +1. © ESO 2005.This investigation has been supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung. The Spanish observations were supported by the Junta de Andalucía and the DGI under project AYA2000-1580

IAA : Información y actualidad astronómica (33)

Sumario : Las estrellas jóvenes “imitan” a los agujeros negros.-- La Nebulosa de la Pipa.-- Galaxias “guisante verde”.-- HISTORIAS DE ASTRONOMÍA. Palomas y elefantes.-- DECONSTRUCCIÓN Y otros ENSAYOS. Misión Sunrise.-- EL “MOBY DICK” DE... Martín Guerrero Roncel (IAA-CSIC).-- ACTUALIDAD.-- ENTRE BASTIDORES.-- CIENCIA: PILARES E INCERTIDUMBRES : Agujeros negros.-- ACTIVIDADES IAA, AGENDA Y RECOMENDADOS.N

Multimode Pulsations of the λ Bootis Star 29 Cygni: The 1995 and 1996 Multisite Campaigns

In this paper we present the results of multisite photometric and spectroscopic campaigns, carried out during the years 1995 and 1996, to study the pulsations of a typical λ Bootis star, 29 Cyg. During the 1995 campaign we found well-defined multiperiodicity in 29 Cyg, which was studied in detail during a multilongitude campaign covering a 65 day time interval in 1996. The frequency analysis of the 1996 campaign's data easily revealed 11 excited low ℓ degree modes with frequencies of oscillation ranging from 20.3 to 37.4 cycles day-1 and mean photometric amplitudes ranging from 10.65 to 0.96 mmag in the V filter. After removing the well-identified frequencies, the discrete Fourier transform of the residuals showed excess power in the 20-40 cycle day-1 domain, which indicates the probable existence of unresolved rich p-mode spectra with photometric V amplitudes below 0.5 mmag. We found a regular spacing of 2.41 cycles day-1 within the modes of 29 Cyg, which was interpreted as the spacing of consecutive even and odd ℓ-values. The asteroseismic luminosity log L/L⊙ = 1.12, calculated from the frequency spacing, is in good agreement with the Hipparcos luminosity log L/L⊙ = 1.16 and with luminosities from photometric and spectroscopic calibrations. Using our multicolor photometry we tentatively identified the dominant f1 = 37.425 cycle day -1 mode as an ℓ= 2, n = 5 mode, and made radial overtone identification for all frequencies. These ranged from n = 2 to 5. Analysis of the photometric data shows the long-term (years) and probable short-term (days) variability of amplitudes for all of these modes in 29 Cyg. Using our multicolor WBVR filter photometry, we found the wavelength dependence of the pulsation amplitudes for the five highest amplitude modes. Based on the Hα line radial velocity observations of 29 Cyg, we detected multiperiodic radial velocity variations with frequencies of 38.36 and 29.99 cycles day-1 and semiamplitudes of 1.0 and 0.8 km s-1, respectively. These frequencies coincide within the errors with the photometric frequencies of the two highest amplitude modes, 37.425 and 29.775 cycles day-1. For the highest amplitude ℓ = 2, n = 5 mode (37.425 cycles day-1), the radial velocity-to-light amplitude ratio and velocity-to-light phase shift are equal to 2K(Hα)/ Δ V = 94 km mag-1 s-1 and Φf1 = φVr - φV = +0.08 ± 0.01, respectively, and are in good agreement with values for δ Scuti stars. The rich multiperiodic spectrum makes 29 Cyg a promising target for future multisite campaigns. © 2007. The American Astronomical Society. All rights reserved.M. D. E. and K. Y. W. acknowledge their work as part of the research activity of the Astrophysical Research Center for the Structure and Evolution of the Cosmos, which is supported by the Korean Science and Engineering Foundation. The participation of G. H., E. P., and W. W. was supported by the Austrian Fonds zur Förderung der wissenschaftlichen Forschung under grant S-7303. The spectroscopic observations described in this publication were made possible in part by grants R2Q000 and U1C000 from the International Science Foundation and by grant A-05-067 from the ESO C&EE programme. This work was supported in part by US Civilian and Research Development Foundation grant UP2-317.Peer reviewe

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

Strömgren photometry of the δ Scuti star 67 UMa

We present preliminary results derived from the data obtained during five observing campaigns in 2001, 2003, 2004, 2006 and 2007, of the δ Sct-type variable star 67 UMa, at Sierra Nevada Observatory, Spain. The analysis of the data was performed by means of the Fourier Transform method, and results are shown. The intrinsic b-y, m1, c1 values are derived and the physical parameters are determined.This research was supported by the Junta de Andalucía and the Dirección General de Investigación (MCYT) under project AYA 2006-06375.Peer reviewe

Empirical P-L-C relation for δ scuti stars

Empirical period-luminosity-colour (P-L-C) relations are obtained for the four lowest modes corresponding to radial pulsations. Agreement with predicted values indicates that, in general, both Strömgren photometric calibration and pulsation theory work well for these stars. © 1990 Kluwer Academic Publishers.This research was supported by the Dirección General de Investigación Científica y Técnica (DGICT) under project PB0310

The SX Phe stars

A systematic photometry study of SX Phe stars together with high amplitude δ Sct stars have been carried out. The uvbyß indices are obtained and the physical parameters are determined. The results obtained by using the pulsation and evolution theories independently are compared. A good agreement is found. © 1990 Kluwer Academic Publishers.This research was supported by the Dirección General de Investigación Científica y Técnica (DGICT) under project PB0310