Die wêreld en ons

Hoewel die tweespalt tussen die Weste en Ooste nog onveranderd voortduur, het die onmiddellike spanning effens afgeneem of miskien het ons ook so gewoond geraak daaraan dat die abnormale vir ons normaal geword het

Paul Kruger en Cecil Rhodes.

As Paul Kruger ’n galery moes gehad het, behang met die portrette van belangrike manne wie se weë syne gekruis het, sou daar aangetref word ’n bonte versameling bestaande uit gekroonde hoofde van Europesestate, goewerneurs, staatsmanne, hoë amptenare en groot leiersop elke terrein vanaf Bismarck tot Ferdinand de Lesseps

Die grondslae van die unie.

Die huidige Unie fees bied die geleentheid, in besonder vir die Afrikaner,om hom opnuut rekenskap te gee van die basis van sy trou teenoor die Unie. Dit was lank die gebruik om die vraag van trou en lojaliteit as nie van toepassing op die Afrikaans-sprekende deel van die bevolking te beskou nie. Dit souslegs geldig wees vir ons landgenote van Engelse herkoms

Die kolonisasie van Afrika

Anders as Amerika en Asië, wat geografies verder verwyder was van die middelpunt van die Wes-Europese beskawing, het die Afrikaanse kontinent eers laat in die moderne tyd die voorwerp van belangstelling van Europa geword

Jan Christiaan Smuts.

In die geskiedenis van Suid-Afrika was daar geen enkele leier oor wie se persoon soveel meningsverskil bestaan as wyle Generaal Smutsnie. Vereer deur sy partygenote in ons land en tallose bewonderaars dwarsdeur die wêreld, is hy nogtans deur die grootste deel van sy volkas leier verwerp en dikwels gehoon

Politieke Gedagte van die Calvinisme: Hullr verspreiding en invloed

Dit word taamlik algemeen aangeneem dat die demokratiese denke van die moderne tyd sy oorsprong in die 16de eeu het

Symmetry of re-entrant tetragonal phase in Ba1-xNaxFe2As2: Magnetic versus orbital ordering mechanism

Magneto-structural phase transitions in Ba1-xAxFe2As2 (A = K, Na) materials are discussed for both magnetically and orbitally driven mechanisms, using a symmetry analysis formulated within the Landau theory of phase transitions. Both mechanisms predict identical orthorhombic space-group symmetries for the nematic and magnetic phases observed over much of the phase diagram, but they predict different tetragonal space-group symmetries for the newly discovered re-entrant tetragonal phase in Ba1-xNaxFe2As2 (x ~ 0.24-0.28). In a magnetic scenario, magnetic order with moments along the c-axis, as found experimentally, does not allow any type of orbital order, but in an orbital scenario, we have determined two possible orbital patterns, specified by P4/mnc1' and I4221' space groups, which do not require atomic displacements relative to the parent I4/mmm1' symmetry and, in consequence, are indistinguishable in conventional diffraction experiments. We demonstrate that the three possible space groups are however, distinct in resonant X-ray Bragg diffraction patterns created by Templeton & Templeton scattering. This provides an experimental method of distinguishing between magnetic and orbital models

Another exact inflationary solution

A new closed-form inflationary solution is given for a hyperbolic interaction potential. The method used to arrive at this solution is outlined as it appears possible to generate additional sets of equations which satisfy the model. In addition a new form of decaying cosmological constant is presented.Comment: 10 pages, 0 figure

Bose-Einstein Condensation in a Harmonic Potential

We examine several features of Bose-Einstein condensation (BEC) in an external harmonic potential well. In the thermodynamic limit, there is a phase transition to a spatial Bose-Einstein condensed state for dimension D greater than or equal to 2. The thermodynamic limit requires maintaining constant average density by weakening the potential while increasing the particle number N to infinity, while of course in real experiments the potential is fixed and N stays finite. For such finite ideal harmonic systems we show that a BEC still occurs, although without a true phase transition, below a certain ``pseudo-critical'' temperature, even for D=1. We study the momentum-space condensate fraction and find that it vanishes as 1/N^(1/2) in any number of dimensions in the thermodynamic limit. In D less than or equal to 2 the lack of a momentum condensation is in accord with the Hohenberg theorem, but must be reconciled with the existence of a spatial BEC in D=2. For finite systems we derive the N-dependence of the spatial and momentum condensate fractions and the transition temperatures, features that may be experimentally testable. We show that the N-dependence of the 2D ideal-gas transition temperature for a finite system cannot persist in the interacting case because it violates a theorem due to Chester, Penrose, and Onsager.Comment: 34 pages, LaTeX, 6 Postscript figures, Submitted to Jour. Low Temp. Phy