9,504 research outputs found

    Nuclear magnetic resonance implementation of the Deutsch-Jozsa algorithm using different initial states

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    The Deutsch-Jozsa algorithm distinguishes constant functions from balanced functions with a single evaluation. In the first part of this work, we present simulations of the nuclear magnetic resonance (NMR) application of the Deutsch-Jozsa algorithm to a 3-spin system for all possible balanced functions. Three different kinds of initial states are considered: a thermal state, a pseudopure state, and a pair (difference) of pseudopure states. Then, simulations of several balanced functions and the two constant functions of a 5-spin system are described. Finally, corresponding experimental spectra obtained by using a 16-frequency pulse to create an input equivalent to either a constant function or a balanced function are presented, and the results are compared with those obtained from computer simulations.Comment: accepted for publication in the Journal of Chemical Physic

    Modelling the sound absorption of panels with tapered elliptic micro-perforations

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    A theoretical model is developed in the present study to predict the spectral characteristics of the sound absorption of solid panels with tapered elliptic micro-perforations backed by a rigid wall cavity. In the model, plane wave propagation is assumed along the length of the perforation in the presence of a viscous boundary layer at the internal wall of the perforation. End impedances are approximated using results in existing literature. Validation is done using impedance tube measurements. It is confirmed that the present tapered elliptic perforation model can give much better agreement with experimental results than the conventional cylindrical perforation model for all micro-perforation configurations tested. Results also suggest the importance of perforation density in controlling the variation of sound absorption of the panel absorbers upon changes in perforation configurations

    Clinical trial of FK 506 immunosuppression in adult cardiac transplantation

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    The new immunosuppressive agent FK 506 was used as primary immunotherapy in conjunction with low-dose steroids and azathioprine in 72 patients subsequent to orthotopic cardiac transplantation. Overall patient survival at a mean follow-up of 360 days was 92%. The number of episodes of cardiac rejection (grade 3A or greater) within 90 days of transplantation was 0.95 per patient. The actuarial freedom from rejection at 90 days was 41%. Achievement of this level of immunosuppression is comparable with that of cyclosporine-based triple-drug therapy with OKT3 immunoprophylaxis. Thirty percent of patients were tapered off all steroids, and the average steroid dose in the group who received steroids was 8.6 mg of prednisone per day. The incidence of infection reflected the diminished necessity for steroids: seven major infections (10%) and 11 minor infections (16%). Renal dysfunction occurred during the perioperative period in most patients in this trial. However, the incidence of hypertension was 54% compared with 70% during the cyclosporine era. Ten adults underwent successful rescue therapy with FK 506 after cardiac rejection refractory to conventional immunotherapy. Side effects of FK 506 were notably few, and the results of the trial are encouraging for the future of the cardiac transplant recipient. © 1992

    Spin label EPR structural studies of the N-terminus of α-spectrin

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    AbstractSpectrin, a vital component in human erythrocyte, is composed of α- and β-subunits, which associate to form (αβ)2 tetramers. The tetramerization site is believed to involve the α-spectrin N-terminus and the β-spectrin C-terminus. Abnormal interactions in this region may lead to blood disorders. It has been proposed that both termini consist of partial structural domains and that tetramerization involves the association of these partial domains. We have studied the N-terminal region of a model peptide for α-spectrin by making a series of double spin-labeled peptides and studying their dipolar interaction by electron paramagnetic resonance methods. Our results indicate that residues 21–42 of the N-terminus region exhibit an α-helical conformation, even in the absence of β-spectrin

    Daily Sleep Quality is Associated with Daily Cognition in Late-Life

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    Background: Older adults often face sleep disturbance or cognitive decline that goes beyond the scope of normal aging. The present study examined the relationship between self-reported sleep quality and self-reported daytime attention in a community-dwelling sample of older men at the between-persons and within-persons levels of association. Methods: Thirty-eight participants (M age =75.36 years, SD age =7.51 years, range=66-90 years) completed a twice-daily sleep diary for one week. Sleep quality and attention were assessed using a single-item 0-10 rating scales from the morning diary (“How was the quality of your sleep last night?”) and from the evening diary (“How was your attention today?”). A two-level multilevel model was parameterized with days nested within individuals to examine whether nightly sleep quality predicts an individual’s daily attention rating. Results: A multilevel model predicting self-reported attention revealed (1) older individuals who reported better sleep quality reported having better daily attention [Beta=0.64, t(248.15)=10.12, p\u3c0.001] and (2) following a day of above-average sleep quality, older individuals experienced above-average attention [Beta=0.16, t(259.79)=2.75, p=.006]. Conclusion: Not only was overall sleep quality associated with self-reported attention, but a good night\u27s sleep was associated with better self-reported next-day attention. Results point to the potential importance of fluctuations in sleep quality for daytime functioning. Interventions aimed at improving nightly sleep consistency may be worth exploring as methods to improve daytime cognitive functioning in older adults. Support: This work was supported by the Sleep Research Society Foundation/Jazz Pharmaceuticals (001JP13, PI: Dzierzewski) and by the National Institute on Aging of the National Institutes of Health under Award Number K23AG049955 (PI: Dzierzewski), and National Heart Lung and Blood Institute at the National Institutes of Health under award number K24HL143055 (PI: Martin). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or the Department of Veterans Affairs.https://scholarscompass.vcu.edu/gradposters/1089/thumbnail.jp

    Combined liver-kidney transplantation: Analysis of patients with preformed lymphocytotoxic antibody

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    In this report, we address combined liver-kidney transplantation, with particular attention to the apparent phenomenon of protection of kidney allografts to antibody mediated destruction by liver allografts. Four patients were found to have positive crossmatch before the liver phase of the combined transplant (pre-OT/KT samples). These positive crossmatches were due entirely to anti-HLA class I antibodies, as demonstrated by their removal by immunoabsorption on pololed platelets. In three of these patients, post-OT/pre-KT samples showed a conversion to a negative crossmatch (in the fourth patient this was not done). A kidney allograft, harveted from the same donor, was then placed into the recipient, and in patients no. 3, 7, and 12, good initial function was noted. In one of these patients was there evidence of hyperacute rejection. Post-OT/KT samples were collected in patients no. 3, 7, and 8, and then analyzed for the reappearance of donor specific lymphocytotoxic antibodies in the posttransplant period (data on patient no. 12 was not available at time of preparation). Lymphocytotoxic antibodies with donor specificity could not be detected in any of the samples during the first week posttransplant. The decrease in %PRA and conversion of a positive to negative crossmatch following liver transplantation was correlated to the HLA specificty of the antibody found in the pretransplant serum and the HLA type of the tranplanted organs. In the two instances where an HLA specificity could be determined by panel analysis, transplantation with donor organs bearing these HLA specificities led to a specific disppearance of these antibodies during the postransplant phase
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