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The Effective Electron-Positron Potential in Jellium

100%

Stachowiak H. , Boroński E. , Lach J.

nr 3

391-394

One of the methods of determining theoretical annihilation characteristics in real metals is the approximation called Bloch modified ladder approach. In this approach a Bethe-Goldstone type equation is solved with an effective electron-positron potential obtained previously for jellium of the corresponding electron density. If one wishes to include the dependence on the local electron density of the e^{+}-e^{-} effective potential in this formalism, it is necessary to know this potential for jellium, for metallic and above metallic densities. A review of different proposed e^{+}-e^{-} potentials is presented and their correctness is evaluated from the point of view of their application in a Bethe-Goldstone type formalism which is the jellium analogue of Bloch modified ladder approach.

Global Structure of the Falicov-Kimball Model Ground State Phase Diagram

100%

Lach J. , Łyżwa R. , Jędrzejewski J.

nr 2

327-344

The two-state spinless Falicov-Kimball model on a one-dimensional lattice is studied by means of well-controlled numerical procedures. Restricted phase diagrams in the grand-canonical ensemble and at zero temperature are constructed. The evolution of these phase diagrams, as the interaction parameter U is varied, including the band structures corresponding to configurations of localized particles (ions) and densities of mobile particles (electrons), is monitored. The changes observed enable us to draw conclusions for the global structure of the phase diagram and to make a qualitative plot of such a diagram. Particular attention is paid to the possibility of conductor-insulator transitions. The results obtained suggest that the system is an insulator for all U only if the electron and ion densities ρ_{e},ρ_{i} satisfy the conditions: ρ_{e} + ρ_{i} = 1, |ρ_{i} - 1/2| ≤ δ < 1/2. For all other pairs (ρ_{e},ρ_{i}) there is a critical U at which the system undergoes a conductor-insulator transition.

Inv(10) in a patient with hypogonadotropic hypogonadism

88%

Helszer Z. , Lach J. , Nowacka J. , Constantinou M. , Kaluzewski B.

nr 2

225-229

Hypogonadotropic hypogonadism (HH) was diagnosed in a 22-year-old patient with 46,XY,inv(10) karyotype. It may be associated with some gene mutations of chromosome X, (KAL-1: Kallman syndrome; and DAX-1: congenital adrenal hypoplasia), as well as of certain autosomes, including chromosome 10. This study aimed to: (1) elucidate the aetiopathogenesis of the disease in the studied case: (2) diagnose chromosome aberrations as accurately as possible: and (3) determine if the observed clinical picture can be referred to the diagnosed chromosomal aberration or it is a mere coincidence. The FISH technique, with the use of non-commercial DNA probes, was applied for a precise description of chromosome breaking points. The application of FISH enabled karyotype description: 46,XY, inv(10)(p15.2q11.22).ish inv(10)(p15.2q21.3)(p15?3)(q21?3)(p15conq21?2). The SSCP method revealed no mutation within the DAX-1 gene and no deletion in the KAL-1 gene.