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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. [ABSTRACT FROM AUTHOR]

This paper investigates theoretically and numerically local heating effects in plasmon nanofocusing structures with a particular focus on the sharp free-standing metal wedges. The developed model separates plasmon propagation in the wedge from the resultant heating effects. Therefore, this model is only applicable where the temperature increments in a nanofocusing structure are sufficiently small not to result in significant variations of the metal permittivity in the wedge. The problem is reduced to a one-dimensional heating model with a distributed heat source resulting from plasmon dissipation in the metal wedge. A simple heat conduction equation governing the local heating effects in a nanofocusing structure is derived and solved numerically for plasmonic pulses of different lengths and reasonable energies. Both the possibility of achieving substantial local temperature increments in the wedge (with a significant self-influence of the heating plasmonic pulses), and the possibility of relatively weak heating (to ensure the validity of the previously developed nanofocusing theory) are demonstrated and discussed, including the future applications of the obtained results. Applicability conditions for the developed model are also derived and discussed. [ABSTRACT FROM AUTHOR]

We develop a computationally efficient method for the theoretical analysis of thermophoresis of nanoparticles and adatoms on crystalline surfaces (thermal tweezers) for efficient parallel nanofabrication. The analysis of surface diffusion of particles or adatoms in the presence of strong temperature gradients is conducted through the direct determination of probability distributions for diffusing particles, using the numerical solution of the Smoluchowski diffusion equation with varying (temperature-dependent) diffusion constant. The local values of the diffusion constant are determined from the Fokker–Planck equation for the considered crystalline potential of the substrate and local temperature. Steady-state and nonsteady-state particle distributions on the surface are obtained and analyzed in the presence of optically-induced strong temperature gradients. Detailed comparison of this approach with the previously obtained results from the Monte Carlo simulations of the Langevin equation is conducted, demonstrating high computational efficiency, and accuracy of the new method in the high-friction regime. Applicability conditions for the developed method are also determined and discussed. [ABSTRACT FROM AUTHOR]

In this paper, we investigate theoretically and numerically the efficiency of energy coupling from a plasmon generated by a grating coupler at one of the interfaces of a metal wedge into the plasmonic eigenmode (i.e., symmetric or quasisymmetric plasmon) experiencing nanofocusing in the wedge. Thus the energy efficiency of energy coupling into metallic nanofocusing structure is analyzed. Two different nanofocusing structures with the metal wedge surrounded by a uniform dielectric (symmetric structure) and with the metal wedge enclosed between a substrate and a cladding with different dielectric permittivities (asymmetric structure) are considered by means of the geometrical optics (adiabatic) approximation. It is demonstrated that the efficiency of the energy coupling from the plasmon generated by the grating into the symmetric or quasisymmetric plasmon experiencing nanofocusing may vary between ∼50% to ∼100%. In particular, even a very small difference (of ∼1%-2%) between the permittivities of the substrate and the cladding may result in a significant increase in the efficiency of the energy coupling (from ∼50% up to ∼100%) into the plasmon experiencing nanofocusing. Distinct beat patterns produced by the interference of the symmetric (quasisymmetric) and antisymmetric (quasiantisymmetric) plasmons are predicted and analyzed with significant oscillations of the magnetic and electric field amplitudes at both the metal wedge interfaces. Physical interpretations of the predicted effects are based upon the behavior, dispersion, and dissipation of the symmetric (quasisymmetric) and antisymmetric (quasiantisymmetric) film plasmons in the nanofocusing metal wedge. The obtained results will be important for optimizing metallic nanofocusing structures and minimizing coupling and dissipative losses. [ABSTRACT FROM AUTHOR]

We conduct the detailed numerical investigation of a nanomanipulation and nanofabrication technique—thermal tweezers with dynamic evolution of surface temperature, caused by absorption of interfering laser pulses in a thin metal film or any other absorbing surface. This technique uses random Brownian forces in the presence of strong temperature modulation (surface thermophoresis) for effective manipulation of particles/adatoms with nanoscale resolution. Substantial redistribution of particles on the surface is shown to occur with the typical size of the obtained pattern elements of ∼100 nm, which is significantly smaller than the wavelength of the incident pulses used (532 nm). It is also demonstrated that thermal tweezers based on surface thermophoresis of particles/adatoms are much more effective in achieving permanent high maximum-to-minimum concentration ratios than bulk thermophoresis, which is explained by the interaction of diffusing particles with the periodic lattice potential on the surface. Typically required pulse regimes including pulse lengths and energies are also determined. The approach is applicable for reproducing any holographically achievable surface patterns, and can thus be used for engineering properties of surfaces including nanopatterning and design of surface metamaterials. [ABSTRACT FROM AUTHOR]

Using rigorous numerical methods of analysis, this paper investigates nonadiabatic nanofocusing in tapered nanorods with the major emphasis on structural optimization for achieving maximal possible local field enhancement. Simple analytical equations for the determination of the optimal length of the tapered rod are presented and discussed. It is also shown that for the considered structures, optimal taper angle and optimal length of the rod only very weakly depend on the radius of curvature of the rounded tip of the rod. Contrary to this, enhancement of the local electric field at the rounded tip strongly increases with decreasing radius of the tip. Comparison of the numerical results with the adiabatic theory of nanofocusing results in accurate verification of the applicability conditions for adiabatic approximation in tapered nanorods. [ABSTRACT FROM AUTHOR]

We investigated the effect of dielectric filling in a V groove on the propagation parameters of channel plasmon-polariton (CPP) modes. In particular, existence conditions and critical groove angles, mode localization, field structure, dispersion, and propagation distances of CPP modes are analyzed as functions of dielectric permittivity inside the groove. It is demonstrated that increasing dielectric permittivity in the groove results in a rapid increase of mode localization near the tip of the groove and increase of both the critical angles that determine a range of groove angles for which CPP modes can exist. Detailed analysis of the field structure has demonstrated that the maximum of the field in a CPP mode is typically reached at a small distance from the tip of the groove. The effect of rounded tip is also investigated. [ABSTRACT FROM AUTHOR]

We demonstrate that efficient adiabatic nanofocusing of plasmons can be achieved using a sharp metal wedge (thin tapered film) on a dielectric substrate. It is shown that the quasisymmetric (with respect to the charge distribution across the wedge) plasmon mode can experience infinite adiabatic slowing down with both its phase and group velocities reducing to zero as the plasmon propagates towards the tip of the wedge. Conditions for strong local field enhancement near the tip are determined and analyzed. In particular, it is demonstrated that the electric field in the plasmon experiences much stronger local enhancement than the magnetic field. Two distinct asymptotic regimes with the electric field amplitude approaching either zero or infinity at the tip of the wedge (tapered film) are described. The results are compared to adiabatic nanofocusing of plasmons by metallic V grooves and sharp metal wedges in a uniform dielectric. [ABSTRACT FROM AUTHOR]

Nanofocusing of electromagnetic radiation, that is, reducing the cross sections of propagating optical modes far beyond the diffraction limit in dielectric media, can be achieved in tapered metal-dielectric waveguides that support surface plasmon-polariton modes. Although the main principles of nanofocusing were formulated over a decade ago, a deep theoretical understanding and conclusive experimental verification were achieved only a few years ago. These advances have spawned a variety of new important technological possibilities for the efficient delivery, control and manipulation of optical radiation on the nanoscale. Here, we present the underlying physical principles of radiation nanofocusing in metallic nanostructures, overview recent progress and major developments, and consider future directions and potential applications of this subfield of nano-optics. [ABSTRACT FROM AUTHOR]

An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Objective: 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. Methods: 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 (∼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. Results: 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 ∼2 months. Only ∼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 ∼1,400 × 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. Conclusions: 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. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Recent years have seen a rapid expansion of research into nanophotonics based on surface plasmon–polaritons. These electromagnetic waves propagate along metal–dielectric interfaces and can be guided by metallic nanostructures beyond the diffraction limit. This remarkable capability has unique prospects for the design of highly integrated photonic signal-processing systems, nanoresolution optical imaging techniques and sensors. This Review summarizes the basic principles and major achievements of plasmon guiding, and details the current state-of-the-art in subwavelength plasmonic waveguides, passive and active nanoplasmonic components for the generation, manipulation and detection of radiation, and configurations for the nanofocusing of light. Potential future developments and applications of nanophotonic devices and circuits are also discussed, such as in optical signals processing, nanoscale optical devices and near-field microscopy with nanoscale resolution. [ABSTRACT FROM AUTHOR]

A simple semianalytical model of dispersion of nanoparticle aerosols from a busy road in the presence of intensive particle fragmentation is developed. In particular, it is predicted that the total number concentration may be characterized by a significant maximum at an optimal distance from the road. Simple analytical existence conditions of such a maximum are derived. Applicability conditions for the model and the effect of turbulent diffusion and dry deposition of nanoparticles on the theoretical predictions are also discussed. As a result of the comparison of the theoretical predictions with the experimental results on the total number concentration as a function of distance from the road, the typical fragmentation rate coefficient has been determined as ≈0.086 s-1, with an estimated error of ∼30%. [ABSTRACT FROM AUTHOR]

The approximate method of analysis of grazing-angle scattering (GAS), based on allowance for the diffractional divergence of the scattered wave, is justified and extended to GAS in infinitely wide, slanted, periodic gratings. The analysis has revealed an unusual and strong dependence of the pattern of GAS on small variations of mean structural parameters at the grating boundary. Several times increase of already resonantly large scattered wave amplitudes can be achieved in this case. Sharp resonance-like maximums on the angular dependence of the scattered wave amplitude are predicted inside the grating. The theory is extended to the case of GAS of optical modes guided by a slab with a semi-infinite periodic groove array. Physical interpretation of the obtained results is presented. [ABSTRACT FROM AUTHOR]

A strong maximum of absorptivity (as much as dozens of per cent) of bulk shear acoustic waves by an ultra-thin layer of a non-Newtonian fluid between two solid surfaces is shown to be achieved at an optimal layer thickness. This optimal thickness is demonstrated to be usually much smaller than the wavelength and the wave penetration depth in the fluid. The coefficients of reflection, transmission, and absorption of shear waves polarized perpendicular to the plane of incidence are determined as functions of incidence angle, layer thickness, fluid viscosity, relaxation time(s), frequency, and parameters of solids. A frictional contact approximation, in which the layer can be considered as a contact with friction is justified for non-Newtonian fluids. The anomalous absorption of bulk shear waves in thin nonuniform fluid layers with viscosity and/or relaxation time varying across the layer is analyzed in the frictional contact approximation. It is shown that unlike the anomalous absorption in Newtonian fluids, the anomalous absorption in non-Newtonian fluid layers is frequency dependent even in the frictional contact approximation. This dependence is analyzed analytically and numerically. © 1999 Acoustical Society of America. [ABSTRACT FROM AUTHOR]

In this letter, the authors demonstrate that random Brownian forces can be used for effective trapping and manipulation of nanoparticles and molecules on surfaces in the presence of strong temperature modulation. Substantial (approximately two orders of magnitude) increase in the modulation of particle concentration (trapping efficiency) compared to thermophoresis in a bulk medium is predicted and explained by a periodic potential of interaction between a particle/molecule and the crystalline surface. As a result, a new nanofabrication and manipulation technique for creating optically induced complex surface structures with nanoscale resolution below tens of nanometers is proposed and developed. [ABSTRACT FROM AUTHOR]

The article discusses the existence of coupled wedge plasmons (CWP) which propagates along a nano gap of twin metal wedges. This CWP were formed by wedge plasmons which can interact with each other. The study has stated that the dispersion relations of the wavenumber, propagation distance, and beam area of CWP, have showed that the characteristics of CWP were similar to wedge plasmons and gap plasmons.

Clinical and biochemical diversity of Parkinson's disease (PD) presents a major challenge for accurate diagnosis and prediction of its progression. We propose, develop and optimize PD clinical scores as efficient integrated progression biomarkers for prediction of the likely rate of cognitive decline in PD patients. We considered 269 drug-naïve participants from the Parkinson's Progression Marker Initiative database, diagnosed with idiopathic PD and observed between 4 and 6 years. Nineteen baseline clinical and pathological measures were systematically considered. Relative variable importance and logistic regressions were used to optimize combinations of significant baseline measures as integrated biomarkers. Parkinson's disease cognitive decline scores were designed as new clinical biomarkers using optimally categorized baseline measures. Specificities and sensitivities of the biomarkers reached ~93% for prediction of severe rate of cognitive decline (with more than 5 points decline in 4 years on the Montreal Cognitive Assessment scale), and up to ~73% for mild-to-moderate decline (between 1 and 5 points decline). The developed biomarkers and clinical scores could resolve the long-standing clinical problem about reliable prediction of PD progression into cognitive deterioration. The outcomes also provide insights into the contributions of individual clinical and pathological measures to PD progression, and will assist with better-targeted treatment regiments, stratification of clinical trial and their evaluation. [ABSTRACT FROM AUTHOR]

We studied adiabatic nanofocusing of strongly localized surface plasmons in tapered metal rods with parabolic perturbations of the conical shape of the taper. Typical plasmon propagation parameters and local field enhancements are determined along the tapered rod, depending on the shape and plasmon frequency (wavelength). In particular, it is demonstrated that metal rods with tapered convex shape are more efficient in achieving larger local field enhancements at the tip, as compared to rods with the concave shape of the taper. This is explained by weaker dissipative losses in tapered rods with convex shape. In addition, plasmon nanofocusing in tapered rods with convex shape is less sensitive to further variations of the shape. As a result, it is demonstrated that tapered rods with the convex shape could be advantageous for practical applications where strong local field enhancement near the tip is required, and/or where metal rods with relatively large dissipation are used. The obtained results will be important for optimization and practical fabrication of efficient nanofocusing structures using tapered metal rods. [ABSTRACT FROM AUTHOR]

This letter presents the results of an experimental observation and investigation of the recently predicted anomalous absorption of bulk shear acoustic waves polarized normally to the plane of incidence by an ultrathin layer of viscous fluid between two elastic media. Strong increase of the absorptivity of the incident wave by the fluid layer has been observed at layer thicknesses that are much smaller than the wavelength and wave penetration depth into the fluid. A good agreement between the experimental results and the theoretical predictions has been achieved. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]