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    Existence of an information unit as a postulate of quantum theory

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    Does information play a significant role in the foundations of physics? Information is the abstraction that allows us to refer to the states of systems when we choose to ignore the systems themselves. This is only possible in very particular frameworks, like in classical or quantum theory, or more generally, whenever there exists an information unit such that the state of any system can be reversibly encoded in a sufficient number of such units. In this work we show how the abstract formalism of quantum theory can be deduced solely from the existence of an information unit with suitable properties, together with two further natural assumptions: the continuity and reversibility of dynamics, and the possibility of characterizing the state of a composite system by local measurements. This constitutes a new set of postulates for quantum theory with a simple and direct physical meaning, like the ones of special relativity or thermodynamics, and it articulates a strong connection between physics and information.Comment: Published version - 6 pages, 3 appendices, 3 figure

    A Coronal Jet Ejects from Sunspot Light Bridge

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    Chromospheric brighten and Hα\alpha surge are the evident and common phenomena along sunspot light bridge. In this paper, a coronal jet ejects from sunspot light bridge is presented. Using the data from the Solar Dynamics Observatory (SDO) and Hinode satellites, it is confirmed that the jet has the root near light bridge, this suggests that the jet may be a result of reconnection between main sunspot and light bridge. Due to the processing of jet ejects, the intensity and width of light bridge have some changes at some extent. This also suggests that jet is related to the interaction between light bridge and umbra, possibly magnetic reconnection or heat plasma trapped in light bridge escaping and moving along field line.Comment: It has been accepted for publication in PAS

    Rotational friction on small globular proteins: Combined dielectric and hydrodynamic effect

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    Rotational friction on proteins and macromolecules is known to derive contributions from at least two distinct sources -- hydrodynamic (due to viscosity) and dielectric friction (due to polar interactions). In the existing theoretical approaches, the effect of the latter is taken into account in an {\it ad hoc} manner, by increasing the size of the protein with the addition of a hydration layer. Here we calculate the rotational dielectric friction on a protein (ζDF\zeta_{DF}) by using a generalized arbitrary charge distribution model (where the charges are obtained from quantum chemical calculation) and the hydrodynamic friction with stick boundary condition, (ζhydstick\zeta_{hyd}^{stick}) by using the sophisticated theoretical technique known as tri-axial ellipsoidal method, formulated by Harding [S. E. Harding, Comp. Biol. Med. {\bf 12}, 75 (1982)]. The calculation of hydrodynamic friction is done with only the dry volume of the protein (no hydration layer). We find that the total friction obtained by summing up ζDF\zeta_{DF} and ζhydstick\zeta_{hyd}^{stick} gives reasonable agreement with the experimental results, i.e., ζexpζDF+ζhydstick\zeta_{exp} \approx \zeta_{DF} + \zeta_{hyd}^{stick}

    Glucose-targeted niosomes deliver vasoactive intestinal peptide (VIP) to the brain

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    The aim of this study was to evaluate glucose-bearing niosomes as a brain targeted delivery system for the vasoactive intestinal peptide (VIP). To this end, VIP/125I-VIP-loaded glucose-bearing niosomes were intravenously injected to mice. Brain uptake was determined by measuring the radioactivity of 125I-labeled VIP using gamma-counting, after intravenous administration of VIP in solution or encapsulated in glucose-bearing niosomes or in control niosomes. VIP integrity was assessed by reversed-phase HPLC analysis of brain extracts. Distribution of 125I-VIP derived radioactivity was examined from serial brain slices. HPLC analysis confirmed the presence of intact VIP in brain after administration of VIP-loaded niosomes, but not after administration of VIP solution. Encapsulation within glucose-bearing niosomes mainly allowed a significantly higher VIP brain uptake compared to control niosomes (up to 86%, 5min after treatment). Brain distribution of intact VIP after injection of glucose-bearing niosomes, indicated that radioactivity was preferentially located in the posterior and the anterior parts of the brain, whereas it was homogeneously distributed in the whole brain after the administration of control vesicles. In conclusion, this novel vesicular formulation of VIP delivers intact VIP to particular brain regions in mice. Glucose-bearing vesicles might be therefore a novel tool to deliver drugs across the blood-brain barrier (BBB)

    The effects of buserelin microparticles on ovarian function in healthy women

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    Objective. To investigate the tolerance, pharmacokinetics and pharmacodynamJcs of the microparticle fonnulation of buserelin, when it wasaaministered subcutaneously.Design. A single-blind, randomised, parallel-group design was used to investigate the duration of suppression of ovarian function associated with doses of 1,8, 3,6 and 7,2 mg buserelin administered subcutaneously as microparticles.Setting. The study was carried out at the Hoechst Research Centre for Clinical Pharmacology, Department of Pharmacology, University of the Orange Free State, Bloemfontein.Patients. Thirty-two healthy premenopausal female volunteers aged between 19 and 39 years and weighing between 52 and 85 kg completed the study.Outcome measures. Serum progesterone and oestradiol concentrations were measured twice weekly until normal ovarian function resumed, i.e. when serum progesterone concentrations increased to at least 8 nmoVI (a sign of ovulation) and oestradiol concentrations increased to values above 300 pmol/l. Serum and urinary concentrations of buserelin were measured at the same times as those of progesterone and oestradiol.Results. Doses of 1,8,3,6 and 7,2 mg elicited anovulation for mean periods of 52, 77 and 113 days and suppressed ovarian production of oestrogen for 19, 38 and 69 days. Resumption of normal ovarian function occurred when serum buserelin concentrations decreased to between 0,03 and 0,05 lJg/ml. The correlation coefficient between dose and duration of anovulation was 0,75; the correlation coefficient between dose and duration of suppression of oestrogen production was 0,76.Conclusion. Apart from minor side-effects such as hot flushes, vaginal spotting and acne, the compound was tolerated well. We conclude that a good relationship exists between dose and duration of suppression of ovarian function. Doses of 3,6 - 7,2 mg buserelin should suppress oestrogen production for approximately 6 - 9 weeks and ovulation for 11 - 16 weeks

    Development of a 3D model of clinically relevant microcalcifications

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    A realistic 3D anthropomorphic software model of microcalcifications may serve as a useful tool to assess the performance of breast imaging applications through simulations. We present a method allowing to simulate visually realistic microcalcifications with large morphological variability. Principal component analysis (PCA) was used to analyze the shape of 281 biopsied microcalcifications imaged with a micro-CT. The PCA analysis requires the same number of shape components for each input microcalcification. Therefore, the voxel-based microcalcifications were converted to a surface mesh with same number of vertices using a marching cube algorithm. The vertices were registered using an iterative closest point algorithm and a simulated annealing algorithm. To evaluate the approach, input microcalcifications were reconstructed by progressively adding principal components. Input and reconstructed microcalcifications were visually and quantitatively compared. New microcalcifications were simulated using randomly sampled principal components determined from the PCA applied to the input microcalcifications, and their realism was appreciated through visual assessment. Preliminary results have shown that input microcalcifications can be reconstructed with high visual fidelity when using 62 principal components, representing 99.5% variance. For that condition, the average L2 norm and dice coefficient were respectively 10.5 μ\mum and 0.93. Newly generated microcalcifications with 62 principal components were found to be visually similar, while not identical, to input microcalcifications. The proposed PCA model of microcalcification shapes allows to successfully reconstruct input microcalcifications and to generate new visually realistic microcalcifications with various morphologies

    Multiple doses of trandolapril do not affect warfarin pharmacodynamics

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    Objective. The effects of multiple doses of trandolapril (a new angiotensin-converting enzyme inhibitor) on the pharmacodynamics of a single 25 mg dose of warfarin were investigated in 19 men.Design. A double-blind, placebo-controlled cross-over design was used. The study consisted of two periods of 13 days each, during which subjects received either trandolapril 2 mg or placebo once daily according to a randomisation plan. Warfarin was given on day 8 of each of these periods.Setting. The study was carried out at the Hoechst Research Centre for Clinical Pharmacology, Department of Pharmacology, University of the Orange Free State, Bloemfontein.Patients. Nineteen healthy white men aged between 18 and 28 years and weighing between 65 and 98 kg volunteered for the study.Outcome measures. Prothrombin time (PT) and coagulation factors II, VII, IX and X were measured before and sequentially up to 6 days after warfarin administration. Areas under the PT and coagulation factor time curves for warfarin + trandolapril were compared with the corresponding areas for warfarin + placebo. The two treatment combinations were also compared at each measuring time.Results. The point estimate for the ratio of the treatment means of warfarin + trandolapril relative to warfarin + placebo for PT was 97% (90% confidence interval: 90% 103%). The corresponding value for factor VII was 97% (90% confidence interval: 91 % - 102%).Conclusion. The concomitant administration of trandolapril did not affect the pharmacodynamic effects of warfarin
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