Accurate measurement of ^{13}C - ^{15}N distances with solid-state NMR

Solid-state NMR technique for measureing distances between hetero-nuclei in static powder samples is described. It is based on a two-dimensional single-echo scheme enhanced with adiabatic cross-polarization. As an example, the results for intra-molecular distances in $\alpha$-crystalline form of glycine are presented. The measured NMR distances ^13 C(2) - ^15 N and ^13 C(1) - ^15 N are 1.496 $\pm$ 0.002 \AA and 2.50 $\pm$ 0.02 \AA, respectively.Comment: 12 page

Alcohol Induced Psychotic Disorder: a comparitive study in patients with alcohol dependance, schizophrenia and normal controls

Thesis(DMed (Psychiatry))-- University of Stellenbosch, 2007.Alcohol-induced psychotic disorder (also known as alcohol hallucinosis) is a complication of alcohol abuse that requires clinical differentiation from alcohol withdrawal delirium and schizophrenia. Although extensively described, few studies utilized standardized research instruments and brain-imaging has thus far been limited to case reports. The aim of this study was to prospectively compare four population groups (ie. patients with alcohol-induced psychotic disorder, schizophrenia, uncomplicated alcohol dependence and a healthy volunteer group) according to demographic, psychopathological and brainimaging variables utilizing (i) rating scales and (ii) single photon emission computed tomography (SPECT). The third component of the study was designed to investigate the (iii) effect of anti-psychotic treatment on the psychopathology and regional cerebral blood flow (rCBF) before and after six weeks of treatment with haloperidol. Effort was made to ensure exclusion of comorbid medical disorders, including substance abuse. The study provides further supportive evidence that alcohol-induced psychotic disorder can be distinguished from schizophrenia. Statistically significant differences in rCBF were demonstrated between the alcohol-induced psychotic disorder and other groups. Changes in frontal, temporal, parietal, occipital, thalamic and cerebellar rCBF showed statistically significant negative correlations with post-treatment improvement on psychopathological variables and imply dysfunction of these areas in alcohol-induced psychotic disorder. The study was unable to distinguish between pharmacological effects and improvement acccomplished by abstinence from alcohol.Stellenbosch: Stellenbosch Universit

Self-induced water intoxication : a case report

CITATION: Emsley, R. A. & Taljaard, J. J. F. 1988. Self-induced water intoxication : a case report. South African Medical Journal, 74:80-81.The original publication is available at http://www.samj.org.zaA 19-year-old female schizophrenic with self-induced water intoxication is described. Factors of pathogenic significance included primary polydipsia and non-maximal urinary diluting capacity.Publisher’s versio

Psychiatric disorders and general medical conditions: implications for the clinician

Patients with severe mental illness have higher than expected prevalence rates of co-morbid general medical conditions, particularly metabolic and cardiovascular disease. They are also at increased risk of contracting HIV. Conversely, these and other medical disorders also increase the risk of developing mental disorders. Mental illness and general medical conditions have mutually adverse effects on long-term outcome. This interaction of diseases contributes significantly to the excess morbidity in and higher than expected standard mortality ratios for patients with mental illness. As medical practice becomes more specialized and arguably compartmentalized it may increasingly fail to integrate health care for patients with severe mental illness. In this paper we discuss the high co-morbidity of mental illness with other medical disorders as well some of the potential mechanisms involved. We furthermore argue that the bidirectional relationship between mental and medical disorders should be considered in the planning of treatment for either group of disorders. The central role of the psychiatrist in co-ordinating and integrating the health care of patients with severe mental illness is emphasized.African Journal of Psychiatry Vol. 11 (1) 2008: pp. 18-2

Quantum information processing using strongly-dipolar coupled nuclear spins

Dipolar coupled homonuclear spins present challenging, yet useful systems for quantum information processing. In such systems, eigenbasis of the system Hamiltonian is the appropriate computational basis and coherent control can be achieved by specially designed strongly modulating pulses. In this letter we describe the first experimental implementation of the quantum algorithm for numerical gradient estimation on the eigenbasis of a four spin system.Comment: 5 pages, 5 figures, Accepted in PR

Fidelity enhancement by logical qubit encoding

We demonstrate coherent control of two logical qubits encoded in a decoherence free subspace (DFS) of four dipolar-coupled protons in an NMR quantum information processor. A pseudo-pure fiducial state is created in the DFS, and a unitary logical qubit entangling operator evolves the system to a logical Bell state. The four-spin molecule is partially aligned by a liquid crystal solvent, which introduces strong dipolar couplings among the spins. Although the system Hamiltonian is never fully specified, we demonstrate high fidelity control over the logical degrees of freedom. In fact, the DFS encoding leads to higher fidelity control than is available in the full four-spin Hilbert space.Comment: 10 pages, 2 figure

Design of Strongly Modulating Pulses to Implement Precise Effective Hamiltonians for Quantum Information Processing

We describe a method for improving coherent control through the use of detailed knowledge of the system's Hamiltonian. Precise unitary transformations were obtained by strongly modulating the system's dynamics to average out unwanted evolution. With the aid of numerical search methods, pulsed irradiation schemes are obtained that perform accurate, arbitrary, selective gates on multi-qubit systems. Compared to low power selective pulses, which cannot average out all unwanted evolution, these pulses are substantially shorter in time, thereby reducing the effects of relaxation. Liquid-state NMR techniques on homonuclear spin systems are used to demonstrate the accuracy of these gates both in simulation and experiment. Simulations of the coherent evolution of a 3-qubit system show that the control sequences faithfully implement the unitary operations, typically yielding gate fidelities on the order of 0.999 and, for some sequences, up to 0.9997. The experimentally determined density matrices resulting from the application of different control sequences on a 3-spin system have overlaps of up to 0.99 with the expected states, confirming the quality of the experimental implementation.Comment: RevTeX3, 11 pages including 2 tables and 5 figures; Journal of Chemical Physics, in pres