1,107 research outputs found
Computation using Noise-based Logic: Efficient String Verification over a Slow Communication Channel
Utilizing the hyperspace of noise-based logic, we show two string
verification methods with low communication complexity. One of them is based on
continuum noise-based logic. The other one utilizes noise-based logic with
random telegraph signals where a mathematical analysis of the error probability
is also given. The last operation can also be interpreted as computing
universal hash functions with noise-based logic and using them for string
comparison. To find out with 10^-25 error probability that two strings with
arbitrary length are different (this value is similar to the error probability
of an idealistic gate in today's computer) Alice and Bob need to compare only
83 bits of the noise-based hyperspace.Comment: Accepted for publication in European Journal of Physics B (November
10, 2010
Release of cetyl pyridinium chloride from fatty acid chelate temporary dental cement
Objective To determine whether the antimicrobial nature of a fatty acid chelate temporary dental cement can be enhanced by the addition of 5% cetyl pyridinium chloride (CPC).
Materials and methods The temporary cement, Cavex Temporary was employed, and additions of CPC were made to either the base or the catalyst paste prior to mixing the cement. Release of CPC from set cement specimens was followed using reverse-phase HPLC for a period of up to 2 weeks following specimen preparation. Potential interactions between Cavex and CPC were examined by Fourier transform infrared spectroscopy (FTIR) and antimicrobial effects were determined using zone of inhibition measurements after 24âh with disc-shaped specimens in cultured Streptococcus mutans.
Results FTIR showed no interaction between CPC and the components of the cement. CPC release was found to follow a diffusion mechanism for the first 6âh or so, and to equilibrate after approximately 2 weeks, with no significant differences between release profiles when the additive was incorporated into the base or the catalyst paste. Diffusion was rapid, and had a diffusion coefficient of approximately 1âĂâ10â9âm2âsâ1 in both cases. Total release was in the range 10â12% of the CPC loading. Zones of inhibition around discs containing CPC were significantly larger than those around the control discs of CPC-free cement.
Conclusions The antimicrobial character of this temporary cement can be enhanced by the addition of CPC. Such enhancement is of potential clinical value, though further in vivo work is needed to confirm this
COMPARISON OF MODELS AND ESTIMATION OF MISSING PARAMETERS OF SOME MATHEMATICAL MODELS RELATED TO IN SITU DRY MATTER DEGRADATION
ABSTRACT The aim of this study was to estimate missing parameters of the models such as the Orskov, Gompertz, Logistic and Richard models. These missing parameters for some models were estimated on the rapidly soluble fraction, the insoluble but potentially degradable fraction and the partial potentially degradable fraction. No difference was found among the values of these parameters (P>0.05), except for the constant rate of degredation. Besides, other missing parameters of the models studied were: partial dry matter disappearance in rumen for the percent rate at time t (t p ) and Rt p , rate of the partial dry matter disapparance in rumen at the time t p (t 0 , t 25 , t 50 , t 75 and t 95 ). These values and formulas for these values in different time intervals were also obtained. The second objective was especially on the comparison of the results of all t p`s (t 25 , t 50 , t 75 and t 95 ) and Rt p`s (Rt 0 , Rt 25 , Rt 50 , Rt 75 and Rt 95 ) in the models. The results of all t p`s and Rt p`s in the models were compatible with each other (P>0.05). The thirth objective was to investigate the fit performance of the models for in situ degradation studies. Some criteria used with the purpose of evaluating performances of models studied were on the analysis of residual (The Runs test and Durbin Watson) and goodness-of-fit (Residual Mean Square, the coefficient of determination and F-ratio). As a result of this study, while the Orskov model showed the best statistical performance and goodness of fit, the Richard model showed the worst. it is determined that the Gompertz model showed a systematic deviation from the data and is not appropriate for describing in situ data
Quasi-free Compton Scattering from the Deuteron and Nucleon Polarizabilities
Cross sections for quasi-free Compton scattering from the deuteron were
measured for incident energies of 236--260 MeV at the laboratory angle -135
degrees. The recoil nucleons were detected in a liquid-scintillator array
situated at 20 degrees. The measured differential cross sections were used,
with the calculations of Levchuk et al., to determine the polarizabilities of
the bound nucleons. For the bound proton, the extracted values were consistent
with the accepted value for the free proton. Combining our results for the
bound neutron with those from Rose et al., we obtain one-sigma constraints of
alpha_n = 7.6-14.0 and beta_n = 1.2-7.6.Comment: 4 pages, 3 figures, accepted in PR
Automorphisms of graphs of cyclic splittings of free groups
We prove that any isometry of the graph of cyclic splittings of a finitely
generated free group of rank is induced by an outer automorphism
of . The same statement also applies to the graphs of maximally-cyclic
splittings, and of very small splittings.Comment: 22 pages, 5 figures. Small modifications. To appear in Geometriae
Dedicat
Addition of vardenafil into storage solution protects the endothelium in a hypoxia-reoxygenation model
OBJECTIVE: Based upon the well known protective effect of intracellular cyclic guanosine monophosphate (cGMP) accumulation, we tested the hypothesis that storage solution enriched with optimal concentration of the phosphodiestherase-5 inhibitor vardenafil could provide better protection of vascular grafts against reperfusion injury after long-term cold ischaemic storage. METHODS: Isolated thoracic aorta obtained from rats underwent 24-h cold ischaemic preservation in physiological saline or vardenafil (10(-11) M)-supplemented saline solution. Reperfusion injury was simulated by hypochlorite (200 muM) exposure for 30 minutes. Endothelium-dependent vasorelaxation was assessed, and histopathological and molecular-biological examination of the aortic tissue were performed. RESULTS: Compared with the control group, the saline group showed significantly attenuated endothelium-dependent maximal relaxation (Rmax) to acetylcholine after hypoxia-reoxygenation, which was significantly improved by vardenafil supplementation (Rmax control: 98 +/- 1%; saline: 48 +/- 6%; vardenafil: 75 +/- 4%; p < .05). Vardenafil treatment significantly reduced DNA strand breaks (control: 10.6 +/- 6.2%; saline: 72.5 +/- 4.0%; vardenafil: 14.2 +/- 5.2%; p < .05) and increased cGMP score in the aortic wall (control: 8.2 +/- 0.6; saline: 4.5 +/- 0.3; vardenafil: 6.7 +/- 0.6; p < .05). CONCLUSIONS: Our results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction induced by cold storage warm reperfusion, which can be effectively reversed by pharmacological phosphodiesterase-5 inhibition
Higher order forward spin polarizability
As a guideline for future experiments to extract the four (leading) spin
polarizabilities of the nucleon, we have constructed the forward amplitude for
polarized Compton scattering by dispersion integrals. These integrals have been
saturated by recently measured helicity-dependent photoabsorption cross
sections as well as predictions for pion photoproduction multipoles from
several phenomenological descriptions and chiral perturbation theory. The
comparison of these results corroborates the strategy to extract the spin
polarizabilities by fitting them to polarized Compton data and fixing all
higher order spin effects by dispersion relations based on pion photoproduction
multipoles.Comment: 21 pages, 6 figures, 3 Tables; version to appear in Phys. Lett.
Analytical study of quality-biased competition dynamics for memes in social media
The spreading of news, memes and other pieces of information occurring via
online social platforms has a strong and growing impact on our modern
societies, with enormous consequences, that may be beneficial but also
catastrophic. In this work we consider a recently introduced model for
information diffusion in social media taking explicitly into account the
competition of a large number of items of diverse quality. We map the meme
dynamics onto a one-dimensional diffusion process that we solve analytically,
deriving the lifetime and popularity distributions of individual memes. We also
present a mean-field type of approach that reproduces the average stationary
properties of the dynamics. In this way we understand and control the role of
the different ingredients of the model, opening the path for the inclusion of
additional, more realistic, features.Comment: 6 pages + 9 pages of Supplementary Materia
Acute and delayed sulfur mustard toxicity; novel mechanisms and future studies
Sulfur mustard (SM), also known as mustard gas, has been the most widely used chemical weapon. The toxicity of SM as an incapacitating agent is of much greater importance than its ability to cause lethality. Acute toxicity of SM is related to reactive oxygen and nitrogen species, DNA damage, poly(ADP-ribose) polymerase activation and energy depletion within the affected cell. Therefore melatonin shows beneficial effects against acute SM toxicity in a variety of manner. It scavenges most of the oxygen- and nitrogen-based reactants, inhibits inducible nitric oxide synthase, repairs DNA damage and restores cellular energy depletion. The delayed toxicity of SM however, currently has no mechanistic explanation. We propose that epigenetic aberrations may be responsible for delayed detrimental effects of mustard poisoning. Epigenetic refers to the study of changes that influence the phenotype without causing alteration of the genotype. It involves changes in the properties of a cell that are inherited but do not involve a change in DNA sequence. It is now known that in addition to genetic mutations, epimutations can also involve in the pathogenesis of a variety of human diseases. Several actions of melatonin are now delineated by epigenetic actions including modulation of histone acetylation and DNA methylation. Future studies are warranted to clarify whether epigenetic mechanisms are involved in pathogenesis of delayed sulfur mustard toxicity and melatonin alleviates delayed toxicity of this warfare agent
In Vitro Studies of Cells Grown on the Superconductor PrOxFeAs
The recent discovery of arsenic-based high temperature superconductors has
reignited interest in the study of superconductor : biological interfaces.
However, the new superconductor materials involve the chemistry of arsenic,
their toxicity remain unclear [ Nature, 2008, 452(24):922]. In this study the
possible adverse effects of this new family of superconductors on cells have
been examined. Cell culture studies in conjunction with microscopy and
viability assays were employed to examine the influence of arsenic-based
superconductor PrOxFeAs (x=0.75) material in vitro. Imaging data revealed that
cells were well adhered and spread on the surface of the superconductor.
Furthermore, cytotoxicity studies showed that cells were unaffected during the
time-course of the experiments, providing support for the biocompatibility
aspects of PrOxFeAs-based superconductor material.Comment: Are the FeAs based superconductors toxic
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