Time Evolution and Deterministic Optimisation of Correlator Product States

We study a restricted class of correlator product states (CPS) for a spin-half chain in which each spin is contained in just two overlapping plaquettes. This class is also a restriction upon matrix product states (MPS) with local dimension $2^n$ ($n$ being the size of the overlapping regions of plaquettes) equal to the bond dimension. We investigate the trade-off between gains in efficiency due to this restriction against losses in fidelity. The time-dependent variational principle formulated for these states is numerically very stable. Moreover, it shows significant gains in efficiency compared to the naively related matrix product states - the evolution or optimisation scales as $2^{3n}$ for the correlator product states versus $2^{4n}$ for the unrestricted matrix product state. However, much of this advantage is offset by a significant reduction in fidelity. Correlator product states break the local Hilbert space symmetry by the explicit selection of a local basis. We investigate this dependence in detail and formulate the broad principles under which correlator product states may be a useful tool. In particular, we find that scaling with overlap/bond order may be more stable with correlator product states allowing a more efficient extraction of critical exponents - we present an example in which the use of correlator product states is several orders of magnitude quicker than matrix product states.Comment: 19 pages, 14 figure

The visual-oral conditional reasoning test : predicting scholastic misconduct and deception

A student misconduct study and a deception experiment were conducted to establish the validity of the Visual-Oral Conditional Reasoning Test (VCRT). In the misconduct study, students\u27 VCRT scores (n = 225) were compared to university records of scholastic misconduct. Results indicate that VCRT scores were significantly correlated with misconduct (r = .55, p \u3c .05). In the deception experiment, students\u27 VCRT scores (n = 60) were compared to whether or not they engaged in deceptive behavior to get a higher grade on an extra credit project. Results indicate that VCRT scores were significantly correlated with engaging in deceptive behavior (r = .49, p \u3c .05). Implications for future research are discussed

Information gathering and conflict resolution in Polistes wasps

Signals are used to communicate resource-holding potential (RHP) to rivals during contests across a wide range of taxa. A controversial subset of RHP signals are status signals. In the last decade, research on North American populations of the paper wasp Polistes dominulus has provided evidence for a visual status signal based on variable clypeal patterns. However, observations of P. dominulus in its native European range indicate that the use of status signals across populations might be limited in this species. In Part I of this thesis (Chapters 3-5), I investigate status signalling in a Spanish population of P. dominulus. Using choice experiments, I show that clypeal patterns do not signal RHP in the Spanish population. Using large-scale field observations and microsatellite sequencing, I then show that patterns do not reflect individual quality in the wild. Together, these results strongly suggest that the clypeal pattern does not function in conflict resolution in the Spanish population. I conclude Part I by exploring the development of the clypeal patterns. I show that pattern expression is strongly temperature-dependent. This finding may provide an explanation for the variation in the signal value of clypeal patterns between populations. Contests among paper wasps are not limited to conspecific interactions, but may involve interactions with social parasites. In Parts II and III of this thesis (Chapters 6-7), I explore interactions between P. dominulus and the social parasite P. semenowi in the contexts of nest usurpation and conflict over reproduction. By experimentally staging usurpation contests, I show that neither parasites nor hosts gather information about rivals during nest usurpation. I then compare reproduction in parasitised and unparasitised colonies to test the predictions of competing models of reproductive skew. Incomplete control models receive qualified support; however, assumptions of skew models about players’ information gathering abilities are questioned

Temporal characteristics of spoken consonants as discriminants in automatic speech recognition

Three time-varying functions, which can be extracted. directly from the raw speech waveform, are of importance in the field of automatic speech recognition. These functions arc the zero-crossing rate, the turnaround (local maximum or minimum) rate and the amplitude of the speech wave envelope. The aim of the work described here was to assess the feasibility of using these three variables to distinguish between the various consonant phonemes in English speech. The investigation was confined to consonants spoken in isolated consonant-vowel syllables, with the consonant in the initial position. All the consonant phonems which occur in the initial position in English were spoken with each of ten vowel phonemes by four male speakers. The three functions mentioned above wore extracted from the speech wave by computer routines and displayed simultaneously using an on-line C.R.T. display. On these traces, the consonant part of the syllable could be readily distinguished by eye from that of the vowel, and the consonant was normally represented by a single peak on each trace. Further computer routines were evolved to identify these consonant peaks and extract recognition parameters describing the form of the peaks. Mistakes made by these programmes could be corrected manually from observation of the display. An attempt was then made to identify tho consonant phoneme, using the values of the recognition parameters. The recognition algorithms took the form of modified binary threshold decision trees, and the task of designing these algorithms to fit new data was mostly automated. Separate algorithms were constructed to recognise the utterances of each of the four speakers. For the appropriate speakers, the performances of these algorithms were very similar, about 65% of the utterances being classified correctly, with a further 25% of 'possibly' or tentatively correct identifications. The algorithms were, however, greatly speaker dependant, and performance fell off sharply when the speaker was changed. The performance of the algorithms was independent of the vowel spoken a.ft er the consonant sound. For each speaker, satisfactory means were found to identify most of the consonant phonemes except the semi-vowel and nasal sounds. Many similarities could be seen between the four recognition algorithms, and it was concluded that the speaker dependance might be reduced by the use of a differ­ent type of recognition algorithm coupled with normalis­ation of the recognition parameters

Welfare Reform in Agricultural California

When welfare reforms were enacted in 1996, a higher than average percentage of residents in the agricultural heartland of California, the San Joaquin Valley, received cash assistance. Average annual unemployment rates during the 1990s ranged from 12% to 20%, and 15% to 20% of residents in major farming counties received cash benefits. This analysis develops and estimates a two-equation cross-sectionally correlated and timewise autoregressive model to test the hypothesis that in agricultural areas, seasonal work, low earnings, and high unemployment, as well as few entry-level jobs that offer wages and benefits equivalent to welfare benefits, promote welfare use and limit the potential of local labor markets to absorb ex-welfare recipients.cross-sectionally correlated and timewise autoregressive model, farm workers, immigration, welfare reform, Public Economics,

Reviews

Teaching and Learning Materials and the Internet by Ian Forsyth, London: Kogan Page, 1996. ISBN: 0–7494‐ 20596. 181 pages, paperback. £18.99