Simulation of static and random errors on Grover's search algorithm implemented in a Ising nuclear spin chain quantum computer with few qubits

We consider Grover's search algorithm on a model quantum computer implemented on a chain of four or five nuclear spins with first and second neighbour Ising interactions. Noise is introduced into the system in terms of random fluctuations of the external fields. By averaging over many repetitions of the algorithm, the output state becomes effectively a mixed state. We study its overlap with the nominal output state of the algorithm, which is called fidelity. We find either an exponential or a Gaussian decay for the fidelity as a function of the strength of the noise, depending on the type of noise (static or random) and whether error supression is applied (the 2pi k-method) or not.Comment: 18 pages, 8 figures, extensive revision with new figure

Toxic effects of phenothiazines on the eye

Publications about the retinotoxic action of phenothiazine derivatives led the author to undertake an ophthalmological investigation in two psychiatric hospitals in The Netherlands. The pharmacological actions of phenothiazine preparations are listed and a survey of the phenothiazine derivatives which are at present in use is given. Some retinotoxic substances are discussed and a survey is given of the literature on the ocular complications of phenothiazine therapy. The eyes of 561 patients were examined. of whom 541 are included in this study. 343 of these patients(63.4 %) were found to have retinopathy. The correlation between the retinopathy and the total dose of phenothiazine preparations taken. and between the retinopathy and the duration of treatment. was highly significant. The correlation between the retinopathy and the average daily dose taken was significant. The retinopathy was associated with a reduced standing potential of the eye. as determined by electro-oculography. It was possibly responsible for diminished visual acuity in some cases, and for an abnormally large proportion of protans in the group of patients with colour defects. It was not possible to ascribe a more severe retinotoxic action to one or more specific phenothiazine derivatives than to others. In the author's opinion regular examination of the eyes of patients who are being treated with phenothiazine preparations in high dosage and for for a long period of time is indicated

A geometrical model to predict the wear evolution of coated surfaces

The improvement of the thin films production techniques leads to the availability of a wide range of coatings with high mechanical properties difficult to be reached with monolithic materials. Thin coated surfaces reveal promising results in several applications, especially where high wear resistance is required. However, selecting the best solution for an envisaged application is a difficult task because the tribological performance depends on both coating and substrate properties and also on adhesion between the coating and the substrate. Therefore, among the main challenges of the surface engineering are included suitable procedures to assure enough adhesion between the coating and the substrate and calculation methods to predict the wear and the mechanical behaviour of each coating + substrate arrangement. Ball-cratering micro-scale abrasion technique solve partially this problem once it allows to determine the specific wear rates of coating and substrate by only one set of tests done with the coated surfaces. In this paper, prediction models based on the micro-scale abrasion tests, will be presented and discussed. The derived geometrical models allow the study of ball-on-plane contact and also of crossed-cylinders contact. The ability of these models to be applied on coating development was demonstrated applying the prediction criteria to study the effect of coating thickness and the coating intrinsic specific wear rate. The wear evolution forecasted by the model was also compared to experimental results of hard chromium plated steel and very good correlations were reached.http://www.sciencedirect.com/science/article/B6V5B-4NYSH52-2/1/066d4a0412b158d5c7f084db824c899

Study of abrasive resistance of composites for dental restoration by ball-cratering

Two-body abrasion occurs in the mouth whenever there is tooth-to-tooth contact. This is what most dentists call attrition. Abrasive wear may also occur when there is an abrasive slurry interposed between two surfaces, such that the two solid surfaces are not actually in contact, this is called three-body abrasion, with food acting as the abrasive agent, and occurs in the mouth during mastication. Abrasion is the key physiological wear mechanism that is present in dental materials during normal masticatory function. The two main categories of restoration materials are dental amalgam and composite restorative material. Although amalgam has excellent mechanical properties, it also has certain limitations and disadvantages. The main negative factors for amalgam are: aesthetic factor, toxicity of mercury, weak adhesion to healthy dental tissue, duration of restoration, corrosion and feeble resistance to fracture.http://www.sciencedirect.com/science/article/B6V5B-48DXVSV-9/1/89cbc08def34c844243d168488b3bf1

Micro-scale abrasive wear of coated surfaces-prediction models

Micro-scale abrasive wear testing is widely used to characterise thinly coated surfaces. Beyond the several advantages of this technique, the possibility of finding the specific wear rates both for the substrate and for the coating with only one set of tests on coated specimens is certainly an important reason for the rapid spread of the micro-scale abrasive technique. It has not yet been established if the coating and the uncoated substrate can be characterized separately, with the results subsequently being used to calculate the wear characteristics of thin-coated surfaces. This paper concerns the development of a model to predict the behaviour of coated surfaces, based on previous characterisation of the coating and of the substrate in non-perforating tests. By comparison with experimental results, the method developed is used to forecast the abrasion resistance of TiN and of thinly coated copper specimens.http://www.sciencedirect.com/science/article/B6TVV-4FXMD14-6/1/6fd97daa15842d867f59bb04afc3e2c