A Land-Cover Classification for Modeling Natural Land Cover within the IIASA LUC Project

Natural forces have always shaped the global land cover, however resulting in mainly gradual changes. More recently anthropogenic impacts have resulted in fast changes and which dominate the natural impacts in many areas. Many studies to understand these changes and their consequences have been started. One common point of interest is the behavior and classification of the land cover. This kind of information is for example required within modeling activities, that intent to evaluate (for example climate change) impacts on land cover, scale independent. As result of the studies land cover information exists at different places around the world. However, although vegetation and land cover classifications exist already some time large differences have been found and no general accepted way of classification exists, e.g. in the level of detail. The land-cover datasets and the large number of classification systems/map legends differ in spatial resolution, definition, purposes, and outcome. For example the classifications use three different main bases: Eco-physiognomy (=relation between plant structure and its environment), environmental conditions (especially climate) and floristics. Coming up with a consistent classification is a common wish of many modelers. Therefore studies to harmonize the existing classifications have just recently started. Although they yet didn't have come up with the ultimate classification they recommended to start with coming up with a set of important attributes, and define these for the different classes. This is in agreement with other studies, which for example want to derive land cover from satellite data. The following step should be to develop a methodology through which the different classifications could be linked, by using these attributes. We are involved within the project "Modeling land-use/land-cover changes in Europe and Northern-Asia". Although is has not been our purpose to come up with a new land-cover classification, we developed a new list to integrate the land-cover diversity within the large region with small scale information as derived from e.g. case studies activities. In this paper we want describe how the land-cover classification for the modeling part of the project has been set up. First we give a short description of the project. Secondly, we come up with our definition of land cover, we indicate the requirements of a good classification and describe the attributes which are important within the classification. These attributes can be classified into internal, eco-physiognomic attributes, such as leaf phenology, and into environmental attributes. We agree with the UNEP harmonization project that such physiognomic attributes should be used for the basic definition of the classes, but it is our believe that for the evaluation of environmental impacts and for mapping purposes environmental attributes are also required

Molecular gas in QSO host galaxies

We present the results of a survey for CO line emission from a sample of nearby QSO hosts taken from the Hamburg/ESO survey (HES) and the Veron-Cetty and Veron quasar catalogue. From a total of 39 observed sources we clearly detected 5 objects with >10sigma signals (HE 0108-4743, HE 0224-2834, J035818.7-612407, HE 1029-1831, HE 2211-3903). Further 6 sources show marginal detections on the 2sigma level.Comment: 4 pages, 1 figure, submitted to "QSO Hosts: Evolution and Environment", P.D. Barthel, D.B. Sanders, eds., August 2005, Leiden University (The Netherlands), New Astr. Re

Helicity Analysis of Semileptonic Hyperon Decays Including Lepton Mass Effects

Using the helicity method we derive complete formulas for the joint angular decay distributions occurring in semileptonic hyperon decays including lepton mass and polarization effects. Compared to the traditional covariant calculation the helicity method allows one to organize the calculation of the angular decay distributions in a very compact and efficient way. In the helicity method the angular analysis is of cascade type, i.e. each decay in the decay chain is analyzed in the respective rest system of that particle. Such an approach is ideally suited as input for a Monte Carlo event generation program. As a specific example we take the decay $\Xi^0 \to \Sigma^+ + l^- + \bar{\nu}_l$ ($l^-=e^-, \mu^-$) followed by the nonleptonic decay $\Sigma^+ \to p + \pi^0$ for which we show a few examples of decay distributions which are generated from a Monte Carlo program based on the formulas presented in this paper. All the results of this paper are also applicable to the semileptonic and nonleptonic decays of ground state charm and bottom baryons, and to the decays of the top quark.Comment: Published version. 40 pages, 11 figures included in the text. Typos corrected, comments added, references added and update

O(αs) O(\alpha_s) corrections to polarized top decay into a charged Higgs t(↑)→H++b t(\uparrow) \to H^+ + b

We calculate the $O(\alpha_s)$ radiative corrections to polarized top quark decay into a charged Higgs boson and a massive bottom quark in two variants of the two-Higgs-doublet model. The radiative corrections to the polarization asymmetry of the decay may become as large as $25$. We provide analytical formulae for the unpolarized and polarized rates for $m_b \neq 0$ and for $m_b = 0$. For $m_b = 0$ our closed-form expressions for the unpolarized and polarized rates become rather compact.Comment: 24 pages, 5 figures in the text, content modified, comments added, appendices added, references updated, replaced with published versio

O(\alpha_s) corrections to the decays of polarized W^+- and Z bosons into massive quark pairs

We present O(\alpha_s) results on the decays of polarized W^+- and Z bosons into massive quark pairs. The NLO QCD corrections to the polarized decay functions are given up to the second order in the quark mass expansion. We find a surprisingly strong dependence of the NLO polarized decay functions on finite quark mass effects even at the relatively large mass scale of the W^+- and Z bosons. As a main application we consider the decay t -> b + W^+ involving the helicity fractions \rho_{mm} of the W^+ boson followed by the polarized decay W^+(\uparrow) -> q_1 qbar_2 for which we determine the O(\alpha_s) polar angle decay distribution. We also discuss NLO polarization effects in the production/decay process e^+e^- -> Z(\uparrow) -> q qbar.Comment: 25 pages, 2 figures and 1 tabl

Leptonic μ \mu - and τ \tau -decays: mass effects, polarization effects and O(α) O(\alpha) radiative corrections

We calculate the radiative corrections to the unpolarized and the four polarized spectrum and rate functions in the leptonic decay of a polarized $\mu$ into a polarized electron. The new feature of our calculation is that we keep the mass of the final state electron finite which is mandatory if one wants to investigate the threshold region of the decay. Analytical results are given for the energy spectrum and the polar angle distribution of the final state electron whose longitudinal and transverse polarization is calculated. We also provide analytical results on the integrated spectrum functions. We analyze the $m_e \to 0$ limit of our general results and investigate the quality of the $m_e \to 0$ approximation. In the $m_e \to 0$ case we discuss in some detail the role of the $O(\alpha)$ anomalous helicity flip contribution of the final electron which survives the $m_e \to 0$ limit. The results presented in this 0203048 also apply to the leptonic decays of polarized $\tau$-leptons for which we provide numerical results.Comment: 39 pages, 11 postscript figures added. Updated version. Four references added. A few text improvements. Final version to appear in Phys.Rev.

Positive specific heat of the quantum corrected dilaton black hole

Path integral quantization of dilaton gravity in two dimensions is applied to the CGHS model to the first nontrivial order in matter loops. Our approach is background independent as geometry is integrated out exactly. The result is an effective shift of the Killing norm: the apparent horizon becomes smaller. The Hawking temperature which is constant to leading order receives a quantum correction. As a consequence, the specific heat becomes positive and proportional to the square of the black hole mass.Comment: 18 pages, JHEP style, 1 eps figure, v2: extended the discussion, added new formulas for mass change, added three new references (in particular [35]

Polarized top decay into polarized W: t(up)->W(up) + b at O(alpha_s)

We consider the decay of a polarized top quark into a polarized W-boson plus a bottom quark, followed by the decay of the W-boson into a pair of leptons or quarks. The polar angle distribution of the top spin relative to the W-momentum and the polar angle distribution of the lepton (or quark) in the W-rest frame is governed by three polarized and three unpolarized rate functions which are related to the double density matrix elements of the decay $t \to W^+ + b$. We obtain analytical expressions for the $O(\alpha_s)$ radiative corrections to the three polarized and three unpolarized rate functions. We also provide a comprehensive discussion of the dependence of the longitudinal, transverse and normal polarization of the top quarks produced at $e^+e^-$-colliders on beam polarization parameters.Comment: 13 pages, 3 postscript figures added, file standard.sty included, material on normal polarization added, some misprints correcte

Scanning microscopies of superconductors at very low temperatures

We discuss basics of scanning tunneling microscopy and spectroscopy (STM/S) of the superconducting state with normal and superconducting tips. We present a new method to measure the local variations in the Andreev reflection amplitude between a superconducting tip and the sample. This method is termed Scanning Andreev Reflection Spectroscopy (SAS). We also briefly discuss vortex imaging with STM/S under an applied current through the sample, and show the vortex lattice as a function of the angle between the magnetic field and sample's surface