Three Order Parameters in Quantum XZ Spin-Oscillator Models with Gibbsian Ground States

Quantum models on the hyper-cubic d-dimensional lattice of spin-1/2 particles interacting with linear oscillators are shown to have three ferromagnetic ground state order parameters. Two order parameters coincide with the magnetization in the first and third directions and the third one is a magnetization in a continuous oscillator variable. The proofs use a generalized Peierls argument and two Griffiths inequalities. The class of spin-oscillator Hamiltonians considered manifest maximal ordering in their ground states. The models have relevance for hydrogen-bond ferroelectrics. The simplest of these is proven to have a unique Gibbsian ground state.Comment: This is a contribution to the Proc. of the Seventh International Conference ''Symmetry in Nonlinear Mathematical Physics'', published in SIGMA (Symmetry, Integrability and Geometry: Methods and Applications) at http://www.emis.de/journals/SIGMA/ v2: sections 1 and 2 have been rewritten, the main result and the proof have not been change

Fighting for the spoils : Cape burgerschap and faction disputes in Cape Town in the 1770s

Includes bibliographical references.The Cape of Good Hope was rocked by a period of political turmoil at the end of the 1770s and beginning of 1780s. Coenraad Beyers published an extensive study about this period and labelled the protesters: Cape Patriots ("Die Kaapse Patriotte"). In his view they were pre-Afrikaner burghers who, driven by ideological arguments, opposed a colonial VOC tyranny. This thesis aims to revise this analysis, while seeking to demonstrate that late eighteenth century Cape society was marked by a complex and intertwined network of status groups. The burgher protests are used as a case study to illustrate that the Cape settlement was part and parcel of the Dutch empire. The protesters emphasised that their burgerschap was on par with that in cities in the Dutch Republic. The first part of the thesis compares Cape and Dutch burgerschap and argues that the Cape burghers were justified in stating that they were burghers of a city belonging to the United Netherlands. It furthermore becomes clear that the Cape burghers had developed a robust burgher identity. This certainly contributed to the outbreak of the conflict, but was not the determining factor. Because the Cape settlement was essentially a Dutch city, many elements many elements of political and social life derived from the Dutch Republic. One of these was that at the Cape a ruling elite consisting of higher VOC officials and prominent burghers had developed with close familial and entrepreneurial links between them

Endocrine processes underlying victory and defeat in the male rat

The central questions of the present study were:1. does base line hormonal state determine agonistic behavior in male-male encounters? 2. does agonistic behavior affect hormonal state? Such an interrelationship between agonistic behavior and hormonal processes might serve as a regulatory system for behavior, in which hormonal changes due to agonistic experiences mediate behavioral changes after these experiences. The above questions were asked inrelation to gonadal and adrenal hormones. ...Zie: General discussio

The Combinatorics of the Foldings of RNA

RNA, much like DNA, is made up of four building blocks called nucleotides, Adenine, Guanine, Cytosine, and Uracil. These nucleotides form words that like to fold in on itself and bond together, each type of nucleotide bonding with only one other type of nucleotide. Therefore, order and number of nucleotides present will determine how many times the strand of RNA can fold. Using these guidelines, we considered what happens when we have only one bonding pair. Expanding on what was proven in k-Foldability of Words” (2017), we were able to expand on the number of ways a word can fold by adding to the list of ways any word of length 2n can fold. We also approached the problem from a different view by looking at how words with the same length and foldability compare to each other and defining operations between these words

A new spinning technique for hollow fiber ultrafiltration membranes

A new spinning technique for hollow fiber membranes with a densified outer toplayer has been developed in our laboratory. This technique makes use of a new type of spinneret having three concentric orifices. Apart from polymer solution and bore liquid as applied in classical spinnerets a third liquid can be pumped through an outer layer. After a certain contact time with the third liquid the nascent hollow fiber membrane meets the coagulation bath. This spinning technique has been applied to produce hollow fiber ultrafiltration membranes. The presence of poly-vinylpyrrolidone in the polymer solution is shown to be essential to induce a porous toplayer. Membranes having a waterflux of 275 L-m-2-hr-1-bar-1 and BSA retention of 97% have been spun. Although more research has to be done the first results seem to be very promising