The allocation of energy resources in the very long run

This paper investigates the Nordhaus (1973) model developed to understand how markets allocate energy resources. In particular, the model proposes that royalties earned by non-renewable energy producers are closely related to the cost of the backstop energy source, the interest rate and the switching date to the backstop energy source. Here, the paper presents the prices of the main and backstop energy sources, extraction costs and royalties, as well as transport costs, taxes and interest rates, over more than five hundred years in Britain to test the model’s ability to explain very long run market behavior. While the model needs a more rigorous analysis, the very long run data and this crude test suggests that certain episodes might be explained by the model and that others do not appear to be. Also, each of the three explanatory variables do appear to be relevant in these explained episodes. In general, though, energy markets appear to be myopic, unaware of the limits of the non-renewable resource being traded, and only in moments of crisis do they consider the finiteness of the resource and, then, perhaps too dramatically, triggering major new technological, infrastructure and R&D investments

Tracking the effects of rigidity percolation down to the liquid state: relaxational dynamics of binary chalcogen melts

4 pags. ; 4 figs.The stochastic dynamics of binary liquids with formula AxB1-x, x=0–0.4 is investigated by neutron spin-echo spectroscopy. These compositions comprise samples of varying chemical connectivity, ranging from twofold-coordinated liquid Se to higher average coordinated As2S3. The parameters giving the temperature dependence of the relaxation patterns show a quasilinear dependence on the average coordination number. The results thus extend the validity of the rigidity concept into the normal liquid state and emphasize the role played by the fine details of atomic bonding on the dynamics at 10 ps–1 ns scales.Work supported in part by Grant No. MAT2007-65711-C-4-01, MEC, Spain.Peer reviewe

Chloroplast-localized 6-phosphogluconate dehydrogenase is critical for maize endosperm starch accumulation

Plants have duplicate versions of the oxidative pentose phosphate pathway (oxPPP) enzymes with a subset localized to the chloroplast. The chloroplast oxPPP provides NADPH and pentose sugars for multiple metabolic pathways. This study identified two loss-of-function alleles of the Zea mays (maize) chloroplast-localized oxPPP enzyme 6-phosphogluconate dehydrogenase (6PGDH). These mutations caused a rough endosperm seed phenotype with reduced embryo oil and endosperm starch. Genetic translocation experiments showed that pgd3 has separate, essential roles in both endosperm and embryo development. Endosperm metabolite profiling experiments indicated that pgd3 shifts redox-related metabolites and increases reducing sugars similar to starch-biosynthetis mutants. Heavy isotope-labelling experiments indicates that carbon flux into starch is altered in pgd3 mutants. Labelling experiments with a loss of cytosolic 6PGDH did not affect flux into starch. These results support the known role for plastid-localized oxPPP in oil synthesis and argue that amyloplast-localized oxPPP reactions are integral to endosperm starch accumulation in maize kernels

Infrared Spectroscopic Study of a Selection of AGB and Post-AGB Stars

We present here near-infrared spectroscopy in the H and K bands of a selection of nearly 80 stars that belong to various AGB types, namely S type, M type and SR type. This sample also includes 16 Post-AGB (PAGB) stars. From these spectra, we seek correlations between the equivalent widths of some important spectral signatures and the infrared colors that are indicative of mass loss. Repeated spectroscopic observations were made on some PAGB stars to look for spectral variations. We also analyse archival SPITZER mid-infrared spectra on a few PAGB stars to identify spectral features due to PAH molecules providing confirmation of the advanced stage of their evolution. Further, we model the SEDs of the stars (compiled from archival data) and compare circumstellar dust parameters and mass loss rates in different types. Our near-infrared spectra show that in the case of M and S type stars, the equivalent widths of the CO(3-0) band are moderately correlated with infrared colors, suggesting a possible relationship with mass loss processes. A few PAGB stars revealed short term variability in their spectra, indicating episodic mass loss: the cooler stars showed in CO first overtone bands and the hotter ones showed in HI Brackett lines. Our spectra on IRAS 19399+2312 suggest that it is a transition object. From the SPITZER spectra, there seems to be a dependence between the spectral type of the PAGB stars and the strength of the PAH features. Modelling of SEDs showed among the M and PAGB stars that the higher the mass loss rates, the higher the [K-12] colour in our sample.Comment: 14 pages; accepted in MNRAS, 200

Hidden magnetic frustration by quantum relaxation in anisotropic Nd-langasite

The static and dynamic magnetic properties of the Nd$_3$Ga$_5$SiO$_{14}$ compound, which appears as the first materialization of a rare-earth kagome-type lattice, were re-examined, owing to contradictory results in the previous studies. Neutron scattering, magnetization and specific heat measurements were performed and analyzed, in particular by fully taking account of the crystal electric field effects on the Nd$^{3+}$ ions. One of the novel findings is that the peculiar temperature independent spin dynamics observed below 10 K expresses single-ion quantum processes. This would short-circuit the frustration induced cooperative dynamics, which would emerge only at very low temperature

Transverse and longitudinal spin-fluctuations in INVAR Fe0.65Ni0.35

The presence of spin-fluctuations deep within the ordered state of ferromagnetic [Formula: see text] alloy [Formula: see text] has long been suspected but seldom directly observed. Inhomogeneities of one type or another have been cited as important in stabilizing [Formula: see text] behaviour-either longitudinal spin-fluctuations associated with the [Formula: see text]-state (local environment) model or transverse magnetisation arising from non-collinear spin structures. In this study we employ small-angle neutron scattering with neutron polarization analysis to distinguish between the two possibilities. Surprisingly we in fact find evidence of dominant but uncorrelated longitudinal spin-fluctuations coexisting with transverse magnetisation which exists in short-range clusters of size ~[Formula: see text]. This finding supports recent first principles calculations of [Formula: see text] in which both longitudinal spin-fluctuations and magnetic short-range order are identified as important ingredients in reproducing the equilibrium [Formula: see text] lattice

Trip related factors

WP3 of the European Project TRACE is concerned with Types of Factors to analyse the causation of road traffic accidents from a factors' point of view. In task 3.3 'Trip-related Factors' it was tried to characterise accidents that are caused by certain contributing factors found on a trip level. This was done by applying one statistical method to existing databases of the WP3 Partners on the one hand and on the other hand by performing an in-depth case analysis using the WP5 method. The analysed factors stem from the Human Component of the accident causation classification, namely "alcohol", "vigilance", and "experience", from the Vehicle Component, namely "vehicle condition/maintenance", and from the Environment component, namely "road layout" and "road condition". This selection resulted from the task 3.1 conclusions and feasibility reasons. Due to inhomogeneous results for the databases from Austria, France, Germany, Great Britain, and Spain the detailed results will be pictured in an Internal TRACE Report by Sub-reports of the WP3 Partners, in this task report the main results are discussed with respect to findings and data in other databases available to the TRACE partners as requested from WP8. Both methods applied show that trip-related factors are possible to prevent not on a trip level only, but also from a background level and as well on a level closer to the accident (driving task level). However, only some suggestions are possible to give by these results. A more detailed view for preventing the different accidents that result from trip-related factors is necessary, as shown by the results of BASt with the statistic method, as well as by INRETS with the ultra in-depth WP5 method

Tracing kinematical and physical asymmetries in the jet from DG Tau B

Stellar jets can be highly asymmetric and have multiple velocity components. To clarify the origin of jet asymmetries and constrain their launch mechanism we study the physical and kinematical structure of the flow emitted by DG Tau B. The analysis of deep spectra taken at the KECK telescope allows us to infer the physical properties (the electron and total density, ne and nh, the ionisation fraction, xe, and the temperature, te) and the spatial distribution of the velocity components in the two jet lobes. The presence of dust grains in the jet is investigated by estimating the gas-phase abundance of calcium with respect to its solar value. At the base of the jet the lines are broad (~100 km/s) and up to three velocity components are detected. At 5" from the source, however, only the denser and more excited high velocity components survive and the lines are narrower (~10-30 km/s). The jet is strongly asymmetric both in velocity and in its physical structure. The red lobe, slower (~140 km/s) and more collimated, presents low ionisation fractions (xe~0.1-0.4) and temperatures (te<5e3 K), while the total density is up to ~2.5e4 ccm. The blue lobe, faster (~-320 km/s) and less collimated, is also less dense (nh~1e4 ccm) but highly excited (te up to ~5e4 K and xe up to 0.9). The estimated mass loss rate is similar in the two lobes (~6-8e-9 Msol/yr), suggesting that the ejection power is comparable on the two sides of the system, as expected from a magneto-centrifugal ejection mechanism, and that the observed asymmetries are due to different mass load and propagation properties in an inhomogeneous environment. Calcium is strongly depleted, indicating that the jet contains dust grains and, therefore, should originate from a region of the disk extending beyond the dust sublimation radius. The depletion is lower for higher velocities, consistent with dust destruction by shocks.Comment: 14 pages, 9 figures, accepted by A&