The Long Run Demand for Lighting: Elasticities and Rebound Effects in Different Phases of Economic Development

25 p.The provision of artificial light was revolutionised by a series of discontinuous innovations in lighting appliances, fuels, infrastructures and institutions during the nineteenth and twentieth centuries. In Britain, the real price of lighting fell dramatically (3,000-fold between 1800 and 2000) and quality rose. Along with rises in real income and population, these developments meant that total consumption of lighting was 40,000 times greater by2000 than in 1800. The paper presents estimates of the income and price elasticities of demand for lighting services over the past three hundred years, and explores how they evolved. Income and price elasticities increased dramatically (to 3.5 and -1.7, respectively) between the 1840s and the 1890s and fell rapidly in the twentieth century. Even in the twentieth century and at the beginning of the twenty-first century, rebound effects in the lighting market still appear to be potentially important. This paper provides a first case study of the long run effects of socio-economic change and technological innovation on the consumption of energy services in the UK. We suggest that understanding the evolution of the demand for energy services and the factors that influence it contributes to a better understanding of future energy uses and associated greenhouse gas emissions

Time-Dependent MHD Shocks and Line Emission: The Case of the DG Tau Jet

The line emission from a growing number of Herbig-Haro jets can be observed and resolved at angular distances smaller than a few arcseconds from the central source. The interpretation of this emission is problematic, since the simplest model of a cooling jet cannot sustain it. It has been suggested that what one actually observes are shocked regions with a filling factor of $\sim 1$. In this framework, up to now, comparisons with observations have been based on stationary shock models. Here we introduce for the first time the self-consistent dynamics of such shocks and we show that considering their properties at different times, i.e. locations, we can reproduce observational data of the DG Tau microjet. In particular, we can interpret the spatial behavior of the [SII]6716/6731 and [NII]/[OI]6583/6300 line intensity ratios adopting a set of physical parameters that yield values of mass loss rates and magnetic fields consistent with previous estimates. We also obtain the values of the mean ionization fraction and electron density along the jet, compare these values with the ones derived from observations using the sulfur doublet to constrain the electron density (e.g. Bacciotti et al. 1995).Comment: 6 pages, 3 figure

HST NICMOS Images of the HH 7/11 Outflow in NGC1333

We present near infrared images in H2 at 2.12um of the HH 7/11 outflow and its driving source SVS 13 taken with HST NICMOS 2 camera, as well as archival Ha and [SII] optical images obtained with the WFPC2 camera. The NICMOS high angular resolution observations confirm the nature of a small scale jet arising from SVS 13, and resolve a structure in the HH 7 working surface that could correspond to Mach disk H2 emission. The H2 jet has a length of 430 AU (at a distance of 350 pc), an aspect ratio of 2.2 and morphologically resembles the well known DG Tau optical micro-jet. The kinematical age of the jet (approx. 10 yr) coincides with the time since the last outburst from SVS 13. If we interpret the observed H2 flux density with molecular shock models of 20-30 km/s, then the jet has a density as high as 1.e+5 cc. The presence of this small jet warns that contamination by H2 emission from an outflow in studies searching for H2 in circumstellar disks is possible. At the working surface, the smooth H2 morphology of the HH 7 bowshock indicates that the magnetic field is strong, playing a major role in stabilizing this structure. The H2 flux density of the Mach disk, when compared with that of the bowshock, suggests that its emission is produced by molecular shocks of less than 20 km/s. The WFPC2 optical images display several of the global features already inferred from groundbased observations, like the filamentary structure in HH 8 and HH 10, which suggests a strong interaction of the outflow with its cavity. The H2 jet is not detected in {SII] or Ha, however, there is a small clump at approx. 5'' NE of SVS 13 that could be depicting the presence either of a different outburst event or the north edge of the outflow cavity.Comment: 13 pages, 5 figures (JPEGs

Long run trends in energy services, 1300-2000

Over the last five centuries, industrialised societies have experienced major technological innovation, mass production of equipment, expansion of energy infrastructures and networks and falling costs of fuels. This has meant cheaper heating, power, transport and lighting. This paper presents evidence on the decline in the cost of these energy services and the associated rise in energy service use, from the fourteenth century to the present day, in what was to become the United Kingdom. For most of the services (i.e. heat, power, transport and lighting), there was an upward trend in average energy prices during the second-half of the nineteenth century and much of the twentieth century. During the period, energy systems were dramatically altered with large scale substitution towards more expensive but higher ‘quality’ fuels. From the beginning of the nineteenth century on, though, the average efficiency for energy services always improves. This means that, since 1750, apart from a brief period of stagnation in the first half of the nineteenth for power and transport, Britain experienced consistently declining prices of energy services. We also found that, since the Industrial Revolution, demand for power, transport and to a less extent lighting appear to be inelastic. However, in the last fifty years, power and transport demand have become far more sensitive to declining prices and rising income levels

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

Three-Dimensional Simulations of Jets from Keplerian Disks: Self--Regulatory Stability

We present the extension of previous two-dimensional simulations of the time-dependent evolution of non-relativistic outflows from the surface of Keplerian accretion disks, to three dimensions. The accretion disk itself is taken to provide a set of fixed boundary conditions for the problem. The 3-D results are consistent with the theory of steady, axisymmetric, centrifugally driven disk winds up to the Alfv\'en surface of the outflow. Beyond the Alfv\'en surface however, the jet in 3-D becomes unstable to non-axisymmetric, Kelvin-Helmholtz instabilities. We show that jets maintain their long-term stability through a self-limiting process wherein the average Alfv\'enic Mach number within the jet is maintained to order unity. This is accomplished in at least two ways. First, poloidal magnetic field is concentrated along the central axis of the jet forming a ``backbone'' in which the Alfv\'en speed is sufficiently high to reduce the average jet Alfv\'enic Mach number to unity. Second, the onset of higher order Kelvin-Helmholtz ``flute'' modes (m \ge 2) reduce the efficiency with which the jet material is accelerated, and transfer kinetic energy of the outflow into the stretched, poloidal field lines of the distorted jet. This too has the effect of increasing the Alfv\'en speed, and thus reducing the Alfv\'enic Mach number. The jet is able to survive the onset of the more destructive m=1 mode in this way. Our simulations also show that jets can acquire corkscrew, or wobbling types of geometries in this relatively stable end-state, depending on the nature of the perturbations upon them. Finally, we suggest that jets go into alternating periods of low and high activity as the disappearance of unstable modes in the sub-Alfv\'enic regime enables another cycle of acceleration to super-Alfv\'enic speeds.Comment: 57 pages, 22 figures, submitted to Ap

Multidisciplinary intensive functional restoration versus outpatient active physiotherapy in chronic low back pain: a randomized controlled trial.

STUDY DESIGN: Randomized parallel group comparative trial with a 1-year follow-up period. OBJECTIVE: To compare in a population of patients with chronic low back pain, the effectiveness of a functional restoration program (FRP), including intensive physical training and a multidisciplinary approach, with an outpatient active physiotherapy program at 1-year follow-up. SUMMARY OF BACKGROUND DATA: Controlled studies conducted in the United States and in Northern Europe showed a benefit of FRPs, especially on return to work. Randomized studies have compared these programs with standard care. A previously reported study presented the effectiveness at 6 months of both functional restoration and active physiotherapy, with a significantly greater reduction of sick-leave days for functional restoration. METHODS: A total of 132 patients with low back pain were randomized to either FRP (68 patients) or active individual therapy (64 patients). One patient did not complete the FRP; 19 patients were lost to follow-up (4 in the FRP group and 15 in the active individual treatment group). The number of sick-leave days in 2 years before the program was similar in both groups (180 ± 135.1 days in active individual treatment vs. 185 ± 149.8 days in FRP, P = 0.847). RESULTS: In both groups, at 1-year follow-up, intensity of pain, flexibility, trunk muscle endurance, Dallas daily activities and work and leisure scores, and number of sick-leave days were significantly improved compared with baseline. The number of sick-leave days was significantly lower in the FRP group. CONCLUSION: Both programs are efficient in reducing disability and sick-leave days. The FRP is significantly more effective in reducing sick-leave days. Further analysis is required to determine if this overweighs the difference in costs of both programs

Table ronde sur la place de la chirurgie dans les douleurs chroniques du membre supérieur

RésuméLa douleur chronique est d’origine plurifactorielle, elle réalise une véritable maladie à la fois neuromusculaire et psychosociale. Elle met en jeu l’individu dans sa globalité. Il ne faut pas limiter la consultation à une approche uniquement physique et ne pas s’abriter derrière des examens complémentaires inutiles. Il faut savoir écouter le patient, rechercher des éléments de catastrophisme, une hypervigilance, une stratégie d’évitement et évaluer le contexte socioprofessionnel. Le rôle des facteurs psychosociaux est déterminant dans le processus de chronicisation de la douleur et quant aux possibilités de réinsertion professionnelle. La place de la chirurgie peut se résumer au traitement d’une épine irritative (facteur déclenchant) sous réserve qu’elle soit toujours active et que sa suppression permette la régression de l’ensemble du tableau. Mais, le plus souvent, les signes sont mal limités avec une hypersensibilisation plus ou moins diffuse et un dysfonctionnement secondaire de l’ensemble du membre supérieur, une exclusion fonctionnelle et des éléments de déconditionnement sont présents et le contexte psychosocial est défavorable. La prise en charge ne peut alors être que pluridisciplinaire et réalisée au mieux en centre de réadaptation