Regge Asymptotics of Scattering with Flavour Exchange in QCD

The contribution to the perturbative Regge asymptotics of the exchange of two reggeized fermions with opposite helicity is investigated. The methods of conformal symmetry known for the case of gluon exchange are extended to this case where double-logarithmic contributions dominate the asymptotics. The Regge trajectories at large momentum transfer are calculated.Comment: 18 pages LATEX, 3 figures using package FEYNMAN, N3-9

Impeller blade design method for centrifugal compressors

The design of a centrifugal impeller with blades that are aerodynamically efficient, easy to manufacture, and mechanically sound is discussed. The blade design method described here satisfies the first two criteria and with a judicious choice of certain variables will also satisfy stress considerations. The blade shape is generated by specifying surface velocity distributions and consists of straight-line elements that connect points at hub and shroud. The method may be used to design radially elemented and backward-swept blades. The background, a brief account of the theory, and a sample design are described

Preliminary Orbit Determination System (PODS) for Tracking and Data Relay Satellite System (TDRSS)-tracked target Spacecraft using the homotopy continuation method

The Preliminary Orbit Determination System (PODS) provides early orbit determination capability in the Trajectory Computation and Orbital Products System (TCOPS) for a Tracking and Data Relay Satellite System (TDRSS)-tracked spacecraft. PODS computes a set of orbit states from an a priori estimate and six tracking measurements, consisting of any combination of TDRSS range and Doppler tracking measurements. PODS uses the homotopy continuation method to solve a set of nonlinear equations, and it is particularly effective for the case when the a priori estimate is not well known. Since range and Doppler measurements produce multiple states in PODS, a screening technique selects the desired state. PODS is executed in the TCOPS environment and can directly access all operational data sets. At the completion of the preliminary orbit determination, the PODS-generated state, along with additional tracking measurements, can be directly input to the differential correction (DC) process to generate an improved state. To validate the computational and operational capabilities of PODS, tests were performed using simulated TDRSS tracking measurements for the Cosmic Background Explorer (COBE) satellite and using real TDRSS measurements for the Earth Radiation Budget Satellite (ERBS) and the Solar Mesosphere Explorer (SME) spacecraft. The effects of various measurement combinations, varying arc lengths, and levels of degradation of the a priori state vector on the PODS solutions were considered

Geophysical data base

A general data-management system that provides a random-access capability for large amounts of data is described. The system operates on a CDC 6400 computer using a combination of magnetic tape and disk storage. A FORTRAN subroutine package is provided to simplify the maintenance and use of the data

High Energy Quark-Antiquark Elastic scattering with Mesonic Exchange

We studies the high energy elastic scattering of quark anti-quark with an exchange of a mesonic state in the $t$ channel with $-t/\Lambda^{2} \gg 1$. Both the normalization factor and the Regge trajectory can be calculated in PQCD in cases of fixed (non-running) and running coupling constant. The dependence of the Regge trajectory on the coupling constant is highly non-linear and the trajectory is of order of $0.2$ in the interesting physical range.Comment: 29 page

Supersymmetric Sudakov corrections

For superpartner masses not much heavier than the weak scale $M=M_{\rm W}$, large logarithmic corrections of the Sudakov type arise at TeV energies. In this paper we discuss the general structure of electroweak supersymmetric (susy) Sudakov corrections in the framework of the infrared evolution equation method. We discuss Yukawa sector Ward-identities which lead to the exponentiation of the subleading (SL) logarithmic Yukawa enhanced Sudakov corrections in both the Standard Model (SM) as well as in softly broken supersymmetric extensions. The results are given to SL accuracy to all orders in perturbation theory for arbitrary external lines in the ``light'' susy-mass scenario. The susy-QCD limit for virtual corrections is presented. Phenomenological applications regarding the precise determination of the important parameter $\tan \beta$ through virtual corrections are discussed which are independent of the soft susy breaking mechanism to sub-subleading accuracy to all orders.Comment: 5 pages, 2 figures, contribution to RADCOR02/Loops and Legs 200

Dynamic approach for micromagnetics close to the Curie temperature

In conventional micromagnetism magnetic domain configurations are calculated based on a continuum theory for the magnetization which is assumed to be of constant length in time and space. Dynamics is usually described with the Landau-Lifshitz-Gilbert (LLG) equation the stochastic variant of which includes finite temperatures. Using simulation techniques with atomistic resolution we show that this conventional micromagnetic approach fails for higher temperatures since we find two effects which cannot be described in terms of the LLG equation: i) an enhanced damping when approaching the Curie temperature and, ii) a magnetization magnitude that is not constant in time. We show, however, that both of these effects are naturally described by the Landau-Lifshitz-Bloch equation which links the LLG equation with the theory of critical phenomena and turns out to be a more realistic equation for magnetization dynamics at elevated temperatures

TESS. La banca dati on-line dei rivestimenti a mosaico

A project undertaken by the University of Padua has developed the new database system TESS for mosaics. This database system meets the national standards required by the Istituto Centrale per il Catalogo e la Documentazione – ICCD. The database is available on-line thanks to the project «Cultural heritage in the Adriatic area: knowledge, preservation and enhancement», co-financed by the Community Initiative INTERREG III A – Adriatic Cross Border Programme. In detail, the database TESS includes informative files regarding Building and Rooms, Location, relevant Bibliography and Mosaic Pavement. Each file contains plans, designs and photographs. Furthermore, all the fields have a list of univocal and exhaustive terms in the Italian language. The mosaics database aims to provide a key working tool for the identification of the origins of iconographic themes, their geographic distribution and the development of local fashions which vary according to the context. The software was developed on a FileMaker client/server environment to achieve these key goals: multiplatform availability (Windows/Macintosh), multiuser capability and remote connectivity. Making wide use of the latest tools included in FileMaker 8, the development group created a smart and complete GUI to access the complex data structure, and at the same time implemented a stringent control of user privileges by setting data-related group policies. The result is a powerful middleware application that allows data entry, analysis and publication to geographically distributed operators and will provide data consultation to other users through normal web browsers