Studies of acoustic emission from point and extended sources

The use of simulated and controlled acoustic emission signals forms the basis of a powerful tool for the detailed study of various deformation and wave interaction processes in materials. The results of experiments and signal analyses of acoustic emission resulting from point sources such as various types of indentation-produced cracks in brittle materials and the growth of fatigue cracks in 7075-T6 aluminum panels are discussed. Recent work dealing with the modeling and subsequent signal processing of an extended source of emission in a material is reviewed. Results of the forward problem and the inverse problem are presented with the example of a source distributed through the interior of a specimen

Odor-driven attractor dynamics in the antennal lobe allow for simple and rapid olfactory pattern classification

The antennal lobe plays a central role for odor processing in insects, as demonstrated by electrophysiological and imaging experiments. Here we analyze the detailed temporal evolution of glomerular activity patterns in the antennal lobe of honeybees. We represent these spatiotemporal patterns as trajectories in a multidimensional space, where each dimension accounts for the activity of one glomerulus. Our data show that the trajectories reach odor-specific steady states (attractors) that correspond to stable activity patterns at about 1 second after stimulus onset. As revealed by a detailed mathematical investigation, the trajectories are characterized by different phases: response onset, steady-state plateau, response offset, and periods of spontaneous activity. An analysis based on support-vector machines quantifies the odor specificity of the attractors and the optimal time needed for odor discrimination. The results support the hypothesis of a spatial olfactory code in the antennal lobe and suggest a perceptron-like readout mechanism that is biologically implemented in a downstream network, such as the mushroom body

Trying to define Free Will : a cognitive and fonctional model proposal

The debate about Free Will has been in the human mind for centuries, but has become even more intense with the recent scientific findings adding new lights on the problem. This interdisciplinary explosion of interest for the topic has brought many insightful knowledge, but also a great deal of epistemological problems. We think that those epistemological problems are deeply related to the very definition of Free Will and how this definition interacts with the interpretations of experimental results. We will thus outline a few of these problems and then propose a definition of Free Will which takes into account those epistemological pitfalls

Anti-inflammatory effects of ciprofloxacin in S. aureus Newman induced nasal inflammation in vitro

<p>Abstract</p> <p>Objectives</p> <p>Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal mucosa. Recent studies suggest that <it>S. aureus </it>enterotoxins may play an etiologic role in the development of CRS. Apart from surgery and repeated courses of steroids, macrolide antibiotics have been reported to exert anti-inflammatory effects in CRS. Similar effects have been reported for fluoroquinolones on various cell types. Since these effects have poorly been characterized in CRS, we examined anti-inflammatory effects of ciprofloxacin on human nasal epithelial cells (HNECs).</p> <p>Methods</p> <p>Inflammation was induced in HNECs cultured from nasal turbinate mucosa with supernatants of <it>S. aureus Newman </it>for 12 hours. Subsequently, HNECs were coincubated with <it>S. aureus Newman </it>and ciprofloxacin (1.5 × 10^-5M), clarithromycin (10^-6M) or prednisolone (10^-5M) for another 12 hours. IL-8 synthesis was quantified after 12 and 24 hours by ELISA.</p> <p>Results</p> <p>Stimulation with <it>S. aureus Newman </it>supernatants was associated with an increase of IL-8 synthesis after 12 hours in all experiments. During the second 12 hours, IL-8 synthesis decreased and this effect was independent from any stimulus or inhibitor. However, coincubation of HNECs with ciprofloxacin was associated with a more extensive decrease of IL-8 synthesis. Similarly, addition of clarithromycin was associated with a reduction of IL-8 synthesis although this effect was not significant. Coincubation with prednisolone resulted in a significant reduction of IL-8 levels.</p> <p>Conclusion</p> <p>Ciprofloxacin exerts anti-inflammatory effects in <it>S. aureus Newman </it>driven nasal inflammation. Inhibitory effects were comparable to those of prednisolone and clarithromycin.</p

Sex differences in cardiovascular responses to orthostatic challenge in healthy older persons: A pilot study

Background Premenopausal women show a higher incidence of orthostatic hypotension than age-matched men, but there are limited data available on sex differences in cardiovascular responses to orthostatic challenge in healthy older persons. We investigated sex differences in hemodynamic and autonomic responses to orthostatic challenge in healthy older males and females. Materials and methods Fourteen older healthy women and 10 age-matched men performed a sit-to-stand test (5 min of sitting followed by 5 min of standing). A Task Force® Monitor continuously measured the following beat-to-beat hemodynamic parameters: heart rate, systolic blood pressure, diastolic blood pressure, mean blood pressure, stroke index, cardiac index, and total peripheral resistance index. Cardiac autonomic activity, low-frequency (LF: 0.04–0.15 Hz) normalized (LFnuRRI) and high-frequency (HF: 0.15–0.4 Hz) normalized (HFnuRRI) components, and the ratio between LF and HF power (LF/HF) were calculated using power spectral analysis of heart rate variability. Results Across all hemodynamic parameters, there were no significant differences between the sexes at baseline and during standing. LFnuRRI (median: 70.2 vs. 52.3, p < 0.05) and LF/HF ratio (median: 2.4 vs. 1.1, p < 0.05) were significantly higher, whereas HFnuRRI (median: 29.8 vs. 47.7, p < 0.05) was lower among women at baseline. All other heart rate variability measures did not differ between the sexes. Conclusions The data indicate that older women showed higher sympathetic and lower parasympathetic activity at rest compared to age-matched men. These results are contradictory to the observations from previous studies, which showed a reduced sympathetic and enhanced parasympathetic activity in women in all ages. Further studies are required to determine the underlying mechanisms contributing to higher incidence of orthostatic hypotension in older females

Interference of Higgs boson resonances in mu^+ mu^- -> neutralino_i neutralino_j with longitudinal beam polarization

We study the interference of resonant Higgs boson exchange in neutralino production in \mu^+ \mu^- annihilation with longitudinally polarized beams. We use the energy distribution of the decay lepton in the process \neutralino_j \to \ell^\pm \slepton^\mp to determine the polarization of the neutralinos. In the CP conserving Minimal Supersymmetric Standard Model a non-vanishing asymmetry in the lepton energy spectrum is caused by the interference of Higgs boson exchange channels with different CP eigenvalues. The contribution of this interference is large if the heavy neutral bosons H and A are nearly degenerate. We show that the asymmetry can be used to determine the couplings of the neutral Higgs bosons to the neutralinos. In particular, the asymmetry allows to determine the relative phase of the couplings. We find large asymmetries and cross sections for a set of reference scenarios with nearly degenerate neutral Higgs bosons.Comment: 20 pages, 6 figures, minor typos corrected, to appear in Eur. Phys. J.

Extended bidomain modeling of defibrillation: quantifying virtual electrode strengths in fibrotic myocardium

Defibrillation is a well-established therapy for atrial and ventricular arrhythmia. Here, we shed light on defibrillation in the fibrotic heart. Using the extended bidomain model of electrical conduction in cardiac tissue, we assessed the influence of fibrosis on the strength of virtual electrodes caused by extracellular electrical current. We created one-dimensional models of rabbit ventricular tissue with a central patch of fibrosis. The fibrosis was incorporated by altering volume fractions for extracellular, myocyte and fibroblast domains. In our prior work, we calculated these volume fractions from microscopic images at the infarct border zone of rabbit hearts. An average and a large degree of fibrosis were modeled. We simulated defibrillation by application of an extracellular current for a short duration (5 ms). We explored the effects of myocyte-fibroblast coupling, intra-fibroblast conductivity and patch length on the strength of the virtual electrodes present at the borders of the normal and fibrotic tissue. We discriminated between effects on myocyte and fibroblast membranes at both borders of the patch. Similarly, we studied defibrillation in two-dimensional models of fibrotic tissue. Square and disk-like patches of fibrotic tissue were embedded in control tissue. We quantified the influence of the geometry and fibrosis composition on virtual electrode strength. We compared the results obtained with a square and disk shape of the fibrotic patch with results from the one-dimensional simulations. Both, one- and two-dimensional simulations indicate that extracellular current application causes virtual electrodes at boundaries of fibrotic patches. A higher degree of fibrosis and larger patch size were associated with an increased strength of the virtual electrodes. Also, patch geometry affected the strength of the virtual electrodes. Our simulations suggest that increased fibroblast-myocyte coupling and intra-fibroblast conductivity reduce virtual electrode strength. However, experimental data to constrain these modeling parameters are limited and thus pinpointing the magnitude of the reduction will require further understanding of electrical coupling of fibroblasts in native cardiac tissues. We propose that the findings from our computational studies are important for development of patient-specific protocols for internal defibrillators

Lie Superalgebras and the Multiplet Structure of the Genetic Code II: Branching Schemes

Continuing our attempt to explain the degeneracy of the genetic code using basic classical Lie superalgebras, we present the branching schemes for the typical codon representations (typical 64-dimensional irreducible representations) of basic classical Lie superalgebras and find three schemes that do reproduce the degeneracies of the standard code, based on the orthosymplectic algebra osp(5|2) and differing only in details of the symmetry breaking pattern during the last step.Comment: 34 pages, 9 tables, LaTe