The Determination of Stellar Parameters of Giants in the Galactic Disks and Bulge

Here, we present our on-going work on the determination of stellar parameters of giants in the Galactic Disks and Bulge observed with UVES on the VLT. We present some preliminarily results.Comment: 2 pages, IAU241 conference proceeding

Response to Invasion by Antigen and Effects of Threshold in an Immune Network Dynamical System Model with a Small Number of Degrees of Freedom

We study a dynamical system model of an idiotypic immune network with a small number of degrees of freedom, mainly focusing on the effect of a threshold above which antibodies can recognise antibodies. The response of the system to invasions by antigens is investigated in the both models with and without the threshold and it turns out that the system changes in a desirable direction for moderate magnitude of perturbation. direction for moderate magnitude of perturbation. Also, the propagation of disturbance by an antigen is investigated in the system of one-dimensionally connected basic units taking the closed 3-clone system as a unit, and it is clarified that the threshold of the system has effects to enhance the stability of the network and to localise the immune response.Comment: 6 pages, 6 figures. Submitted to Prog. Theor. Phy

Strategic Reserves Versus Market-Wide Capacity Mechanisms

Many electricity markets use capacity mechanisms to support generation owners. Capacity payments can mitigate imperfections associated with “missing money” in the spot market and solve transitory capacity shortages caused by investment cycles, regulatory changes, or technology shifts. We discuss capacity mechanisms used in different electricity markets around the world. We argue that strategic reserves, if correctly designed, are likely to be more efficient than market-wide capacity mechanisms. This is especially so in electricity markets that rely on substantial amounts of intermittent generation, hydro power, and energy storage whose available capacity varies with circumstances and is difficult to estimate

The Dynamics of Forest Decline

The anthropogenic emissions into the atmosphere have changed the material flows in the system formed by the atmosphere, vegetation, soil, groundwater, and surface waters. The concentrations of several nutrients and toxic compounds are changing. These concentrations are environmental factors and forests are reacting to the changes in the environment. The material flows are analyzed and basic structures to describe the changing concentrations are outlined. Soil acidification is used as an example of changing environmental factors. The photosynthetic and nutritional response of trees is modeled. Aggregated variables are introduced to describe annual effects of environmental change on metabolism of trees. A stand growth model is described in a static environment and necessary modifications in a changing environment are introduced. A more aggregated model to account for the effects of changing environmental factors on forest growth is described

Anisotropic Distribution of SDSS Satellite Galaxies: Planar (not Polar) Alignment

The distribution of satellite galaxies relative to isolated host galaxies in the Sloan Digital Sky Survey (SDSS) is investigated. Host-satellite systems are selected using three different methods, yielding samples of ~3300, ~1600, and \~950 satellites. In the plane of the sky, the distributions of all three samples show highly significant deviations from circular symmetry (> 99.99%, > 99.99%, and 99.79% confidence levels, respectively), and the degree of anisotropy is a strong function of the projected radius, r_p, at which the satellites are found. For r_p < 100 kpc, the SDSS satellites are aligned preferentially with the major axes of the hosts. This is in stark contrast to the Holmberg effect, in which satellites are aligned with the minor axes of host galaxies. The degree of anisotropy in the distribution of the SDSS satellites decreases with r_p and is consistent with an isotropic distribution at of order the 1-sigma level for 250 kpc < r_p < 500 kpc.Comment: ApJ Letters (in press); Discussion section substantially revised, SDSS DR3 included in the analysis, no significant changes to the result

Central- versus Self-Dispatch in Electricity Markets

In centralized markets, producers submit detailed cost data to the dayahead market, and the market operator decides how much should be produced in each plant. This differs from decentralized markets that rely on self-commitment and where producers send less detailed cost information to the operator of the day-ahead market. Ideally centralized electricity markets would be more effective, as they consider more detailed information, such as start-up costs and no-load costs. On the other hand, the bidding format is rather simplified and does not allow producers to express all details in their costs. Moreover, due to uplift payments, producers have incentives to exaggerate their costs. As of today, US has centralized wholesale electricity markets, while most of Europe has decentralized wholesale electricity markets. The main problem with centralized markets in US is that they do not provide intra-day prices which can be used to continuously up-date the dispatch when the forecast for renewable output changes. Intra-day markets are more flexible and better adapted to deal with renewable power in decentralized markets. Iterative intra-day trading in a decentralized market can also be used to sort out coordination problems related to non-convexities in the production. The downside of this is that increased possibilities to coordinate increase the risk of getting collusive outcomes. Decentralized day-ahead markets in Europe can mainly be improved by considering network constraints in more detail

The Hamburg/ESO R-process Enhanced Star survey (HERES) II. Spectroscopic analysis of the survey sample

We present the results of analysis of ``snapshot'' spectra of 253 metal-poor halo stars -3.8 < [Fe/H] < -1.5 obtained in the HERES survey. The spectra are analysed using an automated line profile analysis method based on the Spectroscopy Made Easy codes of Valenti & Piskunov. Elemental abundances of moderate precision have been obtained for 22 elements, C, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, Sm, and Eu, where detectable. Among the sample of 253 stars, we find 8 r-II stars and 35 r-I stars. We also find three stars with strong enhancements of Eu which are s-process rich. A significant number of new very metal-poor stars are confirmed: 49 stars with [Fe/H] < -3 and 181 stars with -3 < [Fe/H] < -2. We find one star with [Fe/H] < -3.5. We find the scatter in the abundance ratios of Mg, Ca, Sc, Ti, Cr, Fe, Co, and Ni, with respect to Fe and Mg, to be similar to the estimated relative errors and thus the cosmic scatter to be small, perhaps even non-existent. The elements C, Sr, Y, Ba and Eu, and perhaps Zr, show scatter at [Fe/H] < -2.5 significantly larger than can be explained from the errors in the analysis, implying scatter which is cosmic in origin. Significant scatter is observed in abundance ratios between light and heavy neutron-capture elements at low metallicity and low levels of r-process enrichment. (*** abridged ***)Comment: Accepted for A&A; 31 pages, 2 electronic tables presently available at http://www.astro.uu.se/~barklem/papers/heres_tables.tar.gz ; Minor corrections adde

On the Relation Between Peak Luminosity and Parent Population of Type Ia Supernovae: A New Tool for Probing the Ages of Distant Galaxies

We study the properties of Type Ia Supernovae (SNe Ia) as functions of the radial distance from their host galaxy centers. Using a sample of 62 SNe Ia with reliable luminosity, reddening, and decline rate determinations, we find no significant radial gradients of SNe Ia peak absolute magnitudes or decline rates in elliptical+S0 galaxies, suggesting that the diversity of SN properties is not related to the metallicity of their progenitors. We do find that the range in brightness and light curve width of supernovae in spiral galaxies extends to brighter, broader values. These results are interpreted as support for an age, but not metallicity, related origin of the diversity in SNe Ia. If confirmed with a larger and more accurate sample of data, the age-luminosity relation would offer a new and powerful tool to probe the ages and age gradients of stellar populations in galaxies at redshift as high as $z\sim1-2$. The absence of significant radial gradients in the peak $\rm (B-V)_0$ and $\rm (V-I)_0$ colors of SNe Ia supports the redding correction method of Phillips et al (1999). We find no radial gradient in residuals from the SN Ia luminosity-width relation, suggesting that the relation is not affected by properties of the progenitor populations and supporting the reliability of cosmological results based upon the use of SNe Ia as distance indicators.Comment: 19 pages, incl. 3 tables & 3 figures; to appear in Nov 2000 issue of Ap