Non-steady-state extremely asymmetrical scattering of waves in periodic gratings

Extremely asymmetrical scattering (EAS) is a highly resonant type of Bragg scattering with a strong resonant increase of the scattered wave amplitude inside and outside the grating. EAS is realized when the scattered wave propagates parallel to the grating boundaries. We present a rigorous algorithm for the analysis of non-steady-state EAS, and investigate the relaxation of the incident and scattered wave amplitudes to their steady-state values. Non-steady-state EAS of bulk TE electromagnetic waves is analyzed in narrow and wide, slanted, holographic gratings. Typical relaxation times are determined and compared with previous rough estimations. Physical explanation of the predicted effects is presented.Comment: 7 pages, 3 figures. This paper is freely available online at http://www.opticsexpress.org/abstract.cfm?URI=OPEX-10-6-268 which includes multimedia files not included in this preprint versio

Anomalous absorption of bulk shear sagittal acoustic waves in a layered structure with viscous fluid

It is demonstrated theoretically that the absorptivity of bulk shear sagittal waves by an ultra-thin layer of viscous fluid between two different elastic media has a strong maximum (in some cases as good as 100%) at an optimal layer thickness. This thickness is usually much smaller than the penetration depths and lengths of transverse and longitudinal waves in the fluid. The angular dependencies of the absorptivity are demonstrated to have significant and unusual structure near critical angles of incidence. The effect of non-Newtonian properties and non-uniformities of the fluid layer on the absorptivity is also investigated. In particular, it is shown that the absorption in a thin layer of viscous fluid is much more sensitive to non-zero relaxation time(s) in the fluid layer than the absorption at an isolated solid-fluid interface.Comment: 14 pages, 8 figure

Boosting Local Field Enhancement by on-Chip Nanofocusing and Impedance-Matched Plasmonic Antennas

Strongly confined surface plasmon-polariton modes can be used for efficiently delivering the electromagnetic energy to nano-sized volumes by reducing the cross sections of propagating modes far beyond the diffraction limit, i.e., by nanofocusing. This process results in significant local-field enhancement that can advantageously be exploited in modern optical nanotechnologies, including signal processing, biochemical sensing, imaging and spectroscopy. Here, we propose, analyze, and experimentally demonstrate on-chip nanofocusing followed by impedance-matched nanowire antenna excitation in the end-fire geometry at telecom wavelengths. Numerical and experimental evidences of the efficient excitation of dipole and quadrupole (dark) antenna modes are provided, revealing underlying physical mechanisms and analogies with the operation of plane-wave Fabry-P\'erot interferometers. The unique combination of efficient nanofocusing and nanoantenna resonant excitation realized in our experiments offers a major boost to the field intensity enhancement up to $\sim 12000$, with the enhanced field being evenly distributed over the gap volume of $30\times 30\times 10\ {\rm nm}^3$, and promises thereby a variety of useful on-chip functionalities within sensing, nonlinear spectroscopy and signal processing

Psychological stress and psychosomatic treatment: major impact on serious blood disorders?

To demonstrate evidence of possible major impacts of psychological stress and psychosomatic interventions on myeloproliferative blood disorders and develop new approaches for the unification and quantified analysis of stress and psychosomatic treatments.This 3.5- year longitudinal study was based upon the regular blood tests of a person with myelofibrosis who experienced severe and repeated work-related psychological stress and was subjected to psychosomatic treatment in the form of regular (approximately 4 h per day) self-hypnosis sessions. Statistical data analysis was conducted on the basis of an introduced concept of generalized stress that mathematically unifies psychological stress and psychosomatic treatment.Severe stress and psychosomatic treatment were statistically shown to have a major (dominant) impact on blood platelet counts well described by an exponential dependence on cumulative levels of generalized stress. The typical relaxation time for the impacts of both stress and treatment was shown to be approximately 2 months. Only approximately 12% of the total variation in platelet counts could be attributed to factors other than psychological stress and psychosomatic treatment. The psychosomatic intervention resulted in a consistent reduction of high platelet counts from approximately 1,400 x 10⁹ l⁻¹ to approximately the middle of the normal range, with other blood parameters being either approximately stable or showing indications of a strengthening immune system.Our findings give hope for a possible development of psychosomatic treatments of at least some blood disorders. They also indicate a highly instrumental role of platelets in the quantified analysis of stress, psychosomatic interventions, and their neuroimmunological pathways

Multi-channel statistical analysis of combustion aerosols : Part II: Negative correlations of particle modes and fragmentation theorem

This paper develops a new method of statistical analysis of interaction and transformation between different modes in the particle size distribution in atmospheric aerosols in the presence of strong stochastic fluctuations of the environmental and meteorological parameters. Fast processes of mode transformation are investigated in combustion aerosols near a busy road on the basis of the fragmentation mechanism of particle evolution. A unique anti-symmetric correlation pattern between different modes is described and explained by means of the formulated fragmentation theorem. This provides yet another confirmation of the fragmentation mechanisms of aerosol evolution

Path analysis of biomarkers for cognitive decline in early Parkinson's disease.

Clinical and biochemical diversity of Parkinson's disease (PD) and numerous demographic, clinical, and pathological measures influencing cognitive function and its decline in PD create problems with the determination of effects of individual measures on cognition in PD. This is particularly the case where these measures significantly interrelate with each other producing intricate networks of direct and indirect effects on cognition. Here, we use generalized structural equation modelling (GSEM) to identify and characterize significant paths for direct and indirect effects of 14 baseline measures on global cognition in PD at baseline and at 4 years later. We consider 269 drug-naïve participants from the Parkinson's Progression Marker Initiative database, diagnosed with idiopathic PD and observed for at least 4 years after baseline. Two GSEM networks are derived, highlighting the possibility of at least two different molecular pathways or two different PD sub-types, with either CSF p-tau181 or amyloid beta (1-42) being the primary protein variables potentially driving progression of cognitive decline. The models provide insights into the interrelations between the 14 baseline variables, and determined their total effects on cognition in early PD. High CSF amyloid concentrations (> 500 pg/ml) are associated with nearly full protection against cognitive decline in early PD in the whole range of baseline age between 40 and 80 years, and irrespectively of whether p-tau181 or amyloid beta (1-42) are considered as the primary protein variables. The total effect of depression on cognition is shown to be strongly amplified by PD, but not at the time of diagnosis or at prodromal stages. CSF p-tau181 protein could not be a reliable indicator of cognitive decline because of its significantly heterogeneous effects on cognition. The outcomes will enable better understanding of the roles of the clinical and pathological measures and their mutual effects on cognition in early PD

Non Steady State Double Resonant Extremely Asymmetrical Scattering of Waves in Periodic Gratings

Double-resonant extremely asymmetrical scattering (DEAS) is a strongly resonant type of Bragg scattering in two joint or separated uniform gratings with different phases. It is characterised by a very strong increase of the scattered and incident wave amplitudes inside and between the gratings at a resonant phase shift between the gratings. DEAS is realised when the first diffracted order satisfying the Bragg condition propagates parallel to the grating boundaries, and the joint or separated gratings interact by means of the diffractional divergence of the scattered waves from one grating into another. This Letter develops a theory of non-steady-state DEAS of bulk TE electromagnetic waves in holographic gratings, and investigates the process of relaxation of the incident and scattered wave amplitudes to their steady-state values inside and outside the gratings. Typical relaxation times are determined. Physical explanation of the predicted effects is presented