La protección ambiental : una nueva dimensión de la educación.

Título anterior de la publicación : Boletín de la Comisión Española de la UNESCO

La política exterior de Colombia y la internacionalización del proceso de paz (Artículos Varios)

El artículo reflexiona sobre la política exterior de Colombia, sus prioridades y desafíos. Iniciando con un recorrido de lo que fue la diplomacia tradicional colombiana, el autor analiza las relaciones de Colombia con Estados Unidos en la última parte del Siglo XX, caracterizadas por altibajos y por su concentración en el tema de lucha contra las drogas. Fernando Cepeda analiza además el papel de la llamada diplomacia por la paz, las condiciones que dan lugar a la internacionalización del proceso de paz y los objetivos prioritarios que ha definido la política exterior colombiana, alrededor de la búsqueda de una solución definitiva al conflicto armado.

Site Safety and Food Affect Movements of Semipalmated Sandpipers (Calidris pusilla) Migrating Through the Upper Bay of Fundy

The upper Bay of Fundy is a critical stopover site for Semipalmated Sandpipers (Calidris pusilla) during their fall migration. However, little is known about factors that influence selection of feeding and roosting sites by these birds, or the extent to which birds move between different sites during their time in the region. Using radio-telemetry, we studied movement patterns, examined habitat use, and tested hypotheses associated with factors influencing foraging and roost-site selection. Movements of radio-tagged sandpipers were tracked in the upper Bay of Fundy in August 2004 and 2005. In 2004, sandpipers from the Minas Basin, Nova Scotia and Chignecto Bay, New Brunswick and Nova Scotia, were tracked, and in 2005, sandpipers were tracked only in Chignecto Bay. Sandpipers were highly mobile in both the Minas Basin 2004 and Chignecto Bay 2005, making daily movements of up to 20 km between foraging and roosting sites, although very little movement was detected in Chignecto Bay in 2004. Migrating sandpipers appeared to select foraging sites based on relative safety, as measured by distance to cover, provided that these sites offered an adequate food supply. Similarly, roosting sandpipers preferred sites that were far from nearby trees that might offer cover to predators. This preference for safe sites became more apparent later in their stay in the Bay of Fundy, when birds were heavier and, therefore, possibly more vulnerable to predation. Semipalmated Sandpipers appear to be flexible during their time in the upper Bay of Fundy, displaying year-to-year and site-to-site variability in movement and mudflat usage. Therefore, multiple, synchronized population counts should be conducted at known roost sites in order to more accurately estimate Semipalmated Sandpiper abundance in this region. Furthermore, in a highly dynamic system where food can be variable, landscape features such as distance to cover may be important factors to consider when selecting candidate sites for shorebird conservation measures.

Preparation and properties of gallaborane, GaBH6: structure of the gaseous molecule H2Ga(μ-H)2BH2 as determined by vibrational, electron diffraction, and ab initio studies, and structure of the crystalline solid at 110 K as determined by x-ray diffraction``

Gallaborane (GaBH6, 1), synthesized by the metathesis of LiBH4 with [H2GaCl]n at ca. 250 K, has been characterized by chemical analysis and by its IR and 1H and 11B NMR spectra. The IR spectrum of the vapor at low pressure implies the presence of only one species, viz. H2Ga(μ-H)2BH2, with a diborane-like structure conforming to C2v symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements afforced by the results of ab initio molecular orbital calculations. Hence the principal distances (rα in Å) and angles ( α in deg) are as follows: r(Ga•••B), 2.197(3); r(Ga−Ht), 1.555(6); r(Ga−Hb), 1.800(6); r(B−Ht), 1.189(7); r(B−Hb), 1.286(7); Hb−Ga−Hb, 71.6(4); and Hb−B−Hb, 110.0(5) (t = terminal, b = bridging). Aggregation of the molecules occurs in the condensed phases. X-ray crystallographic studies of a single crystal at 110 K reveal a polymeric network with helical chains made up of alternating pseudotetrahedral GaH4 and BH4 units linked through single hydrogen bridges; the average Ga•••B distance is now 2.473(7) Å. The compound decomposes in the condensed phases at temperatures exceeding ca. 240 K with the formation of elemental Ga and H2 and B2H6. The reactions with NH3, Me3N, and Me3P are also described.

The vibrational spectra of natural and perdeuterated monochlorogallane, H2Ga([mu]-Cl)2GaH2, and an empirical harmonic potential function

The infrared and Raman spectra of monochlorogallane and its fully deuterated isotopomer are recorded and assigned on the basis of the dimeric structures. H2Ga(μ-Cl)2GaH2 and D2Ga(μ-Cl)2GaD2, conforming to D2 symmetry. The observed frequencies are corrected for anharmonicity and fitted to a potential function in which 19 of the 33 independent force constants are refined.

Numerical simulation of the 12 May 1997 CME Event: The role of magnetic reconnection

We perform a numerical study of the evolution of a Coronal Mass Ejection (CME) and its interaction with the coronal magnetic field based on the 12 May 1997, CME event using a global MagnetoHydroDynamic (MHD) model for the solar corona. The ambient solar wind steady-state solution is driven by photospheric magnetic field data, while the solar eruption is obtained by superimposing an unstable flux rope onto the steady-state solution. During the initial stage of CME expansion, the core flux rope reconnects with the neighboring field, which facilitates lateral expansion of the CME footprint in the low corona. The flux rope field also reconnects with the oppositely orientated overlying magnetic field in the manner of the breakout model. During this stage of the eruption, the simulated CME rotates counter-clockwise to achieve an orientation that is in agreement with the interplanetary flux rope observed at 1 AU. A significant component of the CME that expands into interplanetary space comprises one of the side lobes created mainly as a result of reconnection with the overlying field. Within 3 hours, reconnection effectively modifies the CME connectivity from the initial condition where both footpoints are rooted in the active region to a situation where one footpoint is displaced into the quiet Sun, at a significant distance (≈1R ) from the original source region. The expansion and rotation due to interaction with the overlying magnetic field stops when the CME reaches the outer edge of the helmet streamer belt, where the field is organized on a global scale. The simulation thus offers a new view of the role reconnection plays in rotating a CME flux rope and transporting its footpoints while preserving its core structure.

Bronze Age barrows on the heathlands of southern England: construction, forms and interpretations

The Bronze Age barrows on the downs of southern England have been investigated and discussed for nearly 200 years, but much less attention has been paid to similar structures in the areas of heathland beyond the chalk and river gravels. They were built in a phase of expansion towards the end of the Early Bronze Age, and more were constructed during the Middle Bronze Age. They have a number of distinctive characteristics. This paper considers the interpretation of these monuments and their wider significance in relation to the pattern of settlement. It also discusses the origins of field systems in lowland England.

A hydrogen-1 nuclear magnetic resonance, mass spectral and extended Hückel study of some olefin complexes of rhodium(I) and iridium(I) and the crystal and molecular structure of η4-2,4-dimethylpenta-1,4-diene(η5-formylcyclopentadienyl)rhodium(I)

A 1H NMR study of monosubstituted η-cyclopentadienyl-rhodium(I) complexes of type LLRh(C5H4X) and -iridium(I) complexes of type L2Ir(C5H4X) (L = ethene, LL = 1,3- or 1,5-diolefin; X = C(C6H5)3, CHO, or COOCH3) has been carried out. For complexes of both metals in which the neutral ligand is ethene or a non-conjugated diolefin the NMR spectra of the cyclopentadienyl protons are unusual in that H(2), H(5) resonate to high field either at room temperature or below. The corresponding NMR spectra for the cyclopentadienyl ring protons of complexes where the neutral ligand is a conjugated diene are, with one exception, normal. A single crystal X-ray structural analysis of (η4-2,4-dimethylpenta-1,4-diene)(η5-formylcyclopentadienyl)rhodium(I) (which exhibits an abnormal 1H NMR spectrum) reveals substantial localisation of electron density in the C(3)C(4) Cp ring bond (1.283(33) Å) which may be consistent with a contribution from an ‘allyl-ene’ rotamer to the ring—metal bonding scheme. An extended Hückel calculation with self consistent charge iteration was performed on this complex. The results predict a greater Mulliken overlap population for the C(3)C(4) bond in the cyclopentadienyl ring and show that the localisation is dependent on both the Cp ring substituent and the nature of the diolefin. The mass spectral fragmentation patterns of some representative diene complexes of iridium(I) and rhodium(I) are presented.

Influence of 10 wk of soy consumption on plasma concentrations and excretion of isoflavonoids and on gut microflora metabolism in healthy adults

Although interindividual variation in isoflavone metabolism was high, intraindividual variation was low. Only concentrations of O-DMA in plasma and urine appeared to be influenced by sex. Chronic soy consumption does not appear to induce many significant changes to the gut metabolism of isoflavones other than higher beta-glucosidase activity.

Ageing and taste

Taste perception has been studied frequently in young and older adult groups. This paper systematically reviews these studies to determine the effect of ageing on taste perception and establish the reported extent of sensory decline. Five databases were searched from 1900 to April 2012. Articles relating to healthy ageing in human subjects were included, reviewed and rated (Downs and Black scoring system). Sixty-nine studies investigated the effect of ageing on taste perception; forty examined detection thresholds of which twenty-three provided sufficient data for meta-analysis, eighteen reported identification thresholds and twenty-five considered supra-threshold intensity perception. Researchers investigating detection thresholds considered between one and thirteen taste compounds per paper. Overall, the consensus was that taste detection thresholds increased with age (Hedges' g = 0·91, P < 0·001), across all taste modalities. Identification thresholds were reported to be higher for older adults in seventeen out of eighteen studies. Sixteen out of twenty-five studies reported perception of taste intensity at supra-threshold levels to be significantly lower for older adults. However, six out of nine studies concerning sucrose found perceived intensity of sweet taste not to diminish with age. The findings of this systematic review suggest taste perception declines during the healthy ageing process, although the extent of decline varies between studies. Overall, the studies reviewed had low Downs and Black scores (mean 16 (SD 2)) highlighting the need for more robust large scale and longitudinal studies monitoring the impact of ageing on the sensory system, and how this influences the perception of foods and beverages.

Securing Peace in Europe, 1945-62: Thoughts for the Post-Cold War Era

Articles include: Beatrice Heuser: ‘Stalin as Hitler's Successor: Western Interpretations of the Soviet threat', pp. 17-40