A unified numerical model of collisional depolarization and broadening rates due to hydrogen atom collisions

Interpretation of solar polarization spectra accounting for partial or complete frequency redistribution requires data on various collisional processes. Data for depolarization and polarization transfer are needed but often missing, while data for collisional broadening are usually more readily available. Recent work by Sahal-Br\'echot and Bommier concluded that despite underlying similarities in the physics of collisional broadening and depolarization processes, relationships between them are not possible to derive purely analytically. We aim to derive accurate numerical relationships between the collisional broadening rates and the collisional depolarization and polarization transfer rates due to hydrogen atom collisions. Such relationships would enable accurate and efficient estimation of collisional data for solar applications. Using earlier results for broadening and depolarization processes based on general (i.e. not specific to a given atom), semi-classical calculations employing interaction potentials from perturbation theory, genetic programming (GP) has been used to fit the available data and generate analytical functions describing the relationships between them. The predicted relationships from the GP-based model are compared with the original data to estimate the accuracy of the method.Comment: 10 pages, 7 figures, Accepted for publication in Astronomy & Astrophysic

Propagation of cracks and dislocations in 2D quasicrystals

A closed-form solution is provided for the stress, strain and velocity fields due to a planar crack steadily propagating in an elastic quasicrystal with fivefold symmetry at speed lower than the bulk wave-speeds. The cases of a semi-infinite rectilinear crack and a Griffith crack which propagates maintaining a constant length, according to the Yoffe model, are considered. Crack face loading and remote loading conditions are taken into consideration. The dynamic theory of quasicrystal with inertia forces, but neglecting dissipative phonon activity, is assumed to govern the motion of the medium. The phonon and phason stress fields turn out to be square-root singular at crack tip. The energy release rate is positive for subsonic and subRayleigh crack propagation

Dispersed fs-FWM for Investigations of Low Frequency Vibrations of Transient Species in Combustion

Understanding the role of peroxides in combustion, in atmospheric and in surface science involves investigations on a molecular level, at which energy transfers and rearrangements of the nuclei dictate the chemistry. Due to their high reactivity they appear as unstable transient species, which impedes detailed spectroscopic investigations. Low frequency modes, especially internal and hindered rotations with energies less than 200 cm-1 play an important role for the determination of molecular energies and reaction rates. Unfortunately, these motions are in general difficult to address. Femtosecond four-wave mixing (fs-FWM) is a powerful tool that allows for investigations of ground state dynamics of molecules. The high peak-power output of fs-lasers, facilitates the excitation of weak Raman coherences. Results from the combustion relevant di-tert-butyl peroxide molecule are exemplified

Gas-phase diagnostics by laser-induced gratings II. Experiments

In this article we review the results achieved in the past ten years at the Paul Scherrer Institute on the topic of diagnostics in the gas phase by laser-induced gratings (LIGs). The technique has been applied for thermometry in air and in flames at different pressures, for flow velocimetry, for concentration measurements, and for imaging purposes. The influence of collisional energy-transfer and relaxation processes in molecules on the temporal evolution of the LIG signals has also been investigated. It has been demonstrated that, for molecules with a low fluorescence quantum yield, excitation of laser-induced thermal gratings can be used as a sensitive spectroscopic tool. For the quantitative interpretation of the experiments shown in this work, the findings presented in the companion paper [1] have been use

Gas phase diagnostics by laser-induced gratings I. theory

Electrostriction and collisional thermalization of absorbed laser energy are the two dominant mechanisms leading to the formation of laser-induced gratings (LIGs) in the gas phase. In this article the results of the theoretical investigations that have been achieved in the past ten years at the Paul Scherrer Institute on this issue are summarized and yield a comprehensive understanding of the underlying physical concepts. Furthermore, a study of the influence of various parameters, such as the alignment and the spatial intensity profile of the beams on the generated electrostrictive and thermal signal is presented for the first time to the authors' knowledge. The variations of the refractive index responsible for the appearance of laser-induced gratings have been theoretically described by solving the linearized hydrodynamic equations. The contributions from electrostriction, as well as from instantaneous and slow relaxation of the absorbed radiation energy into heat is obtained. These expressions are employed for analysis of experimental data presented in the companion paper [1] which is devoted to the application of the technique for diagnostic purposes in the gas phase. Much effort has been undertaken in order to allow a straightforward physical interpretation of the experimental findings of the expressions presented her

Hybrid Neural Network Predictive-Wavelet Image Compression System

This paper considers a novel image compression technique called hybrid predictive wavelet coding. The new proposed technique combines the properties of predictive coding and discrete wavelet coding. In contrast to JPEG2000, the image data values are pre-processed using predictive coding to remove interpixel redundancy. The error values, which are the difference between the original and the predicted values, are discrete wavelet coding transformed. In this case, a nonlinear neural network predictor is utilised in the predictive coding system. The simulation results indicated that the proposed technique can achieve good compressed images at high decomposition levels in comparison to JPEG2000

A position paper on predicting the onset of nocturnal enuresis using advanced machine learning

Bed-wetting during normal sleep in children and young people has a significant impact on the child and their parents. The condition is known as nocturnal enuresis and its underlying cause has been subject to different explanatory factors that include, neurological, urological, sleep, genetic and psychosocial influences. Several clinical and technological interventions for managing nocturnal enuresis exist that include the clinician’s opinions, pharmacology interventions, and alarm systems. However, most have failed to produce any convincing results. Clinical information is often subjective and often inaccurate, the use of desmopressin and tricyclic antidepressants only report between 20 % and 40 % success, and alarms only a 50 % success fate. This position paper posits an alternative research idea concerned with the early detection of impending involuntary bladder release. The proposed framework is a measurement and prediction system that processes moisture and bladder volume data from sensors fitted into undergarments that are used by patients suffering with nocturnal enuresis. The proposed framework represents a level of sophistication in nocturnal enuresis treatment not previously considered

MARKETING MIX STRATEGY DETERMINANTS AND SOCIAL MEDIA IN VETERINARY-BASED BUSINESS: EXPERIENCE FROM SERBIA

The paper is dedicated to testing the entrepreneurial idea of founding a service micro company in the field of veterinary medicine - Animal Care. The starting point is the theoretical aspect of marketing mix services observed through the prism of a specific company in the field of agribusiness. For the needs of the research, secondary sources were used and a survey was conducted which gave the results of the influence of the elements of marketing mix services on marketing communication towards the users of the company Animal Care. It was determined that the effects of promotion, especially in the field of digital marketing, directly affect the increase in sales of products and services, and thus the satisfaction of consumers & users in veterinary services. The results of the research provided answers to research questions and helped the entrepreneur to understand that selected elements of the marketing mix help in the promotion of products and services of Animal Care companies. Respondents showed interest in using the services of the Animal Care company with the help of the Animal Care android application and website as a selected distribution channel, but also for the promotion of new services and offers of the company

MARKETING MIX STRATEGY DETERMINANTS AND SOCIAL MEDIA IN VETERINARY-BASED BUSINESS: EXPERIENCE FROM SERBIA

The paper is dedicated to testing the entrepreneurial idea of founding a service micro company in the field of veterinary medicine - Animal Care. The starting point is the theoretical aspect of marketing mix services observed through the prism of a specific company in the field of agribusiness. For the needs of the research, secondary sources were used and a survey was conducted which gave the results of the influence of the elements of marketing mix services on marketing communication towards the users of the company Animal Care. It was determined that the effects of promotion, especially in the field of digital marketing, directly affect the increase in sales of products and services, and thus the satisfaction of consumers & users in veterinary services. The results of the research provided answers to research questions and helped the entrepreneur to understand that selected elements of the marketing mix help in the promotion of products and services of Animal Care companies. Respondents showed interest in using the services of the Animal Care company with the help of the Animal Care android application and website as a selected distribution channel, but also for the promotion of new services and offers of the company

Analysis of Radicals in Combustion Processes

This work reports on a variety of radical analysis applications in combustion that are performed in the laboratories of the Paul Scherrer Institute. Planar Laser-Induced Fluorescence and Resonant Holographic Interferometry is applied to the two-dimensional imaging of radicals in flames. The potential of Four-Wave Mixing Spectroscopy for non-perturbing combustion diagnostics is investigated and the method is applied to radicals in flames. Phase-Conjugation and the use of two different input frequencies are utilized to address typical problems in a combustion environment, i.e., lensing effects due to temperature and density gradients and congested spectra of the analyte due to significant thermal population of the ground state.More fundamentally, experiments are aimed to obtain detailed knowledge on the spectroscopy of many important radicals that are not yet characterized sufficiently for diagnostic purposes. A molecular beam apparatus has been set up where the collisionless and cold environment provides well defined experimental conditions to produce and investigate the relevant radicals. Finally, temporally and spectrally resolved fluorescence decays in the picosecond time domain are measured in an atmospheric pressure flame. These experiments yield results on vibrational and rotational energy transfer that are required for quantitative laser-induced fluorescence measurements