207 research outputs found

    Laser induced distortion of band structure in solids: an analytic model

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    We consider a spatially periodic (cosine) potential as a model for a crystalline solid that interacts with a harmonically oscillating external electric field. This problem is periodic both in space and time and can be solved analytically using the Kramers-Henneberger co-moving frame. By analyzing the stability of the closely related Mathieu-type differential equation, the electronic band structure can be obtained. We demonstrate that by changing the field intensity, the width of the zero-field band gaps can be drastically modified, including the special case when the external field causes the band gaps to disappearComment: 8 pages, 3 figure

    Electron Acceleration in Underdense Plasmas Described with a Classical Effective Theory

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    An effective theory of laser--plasma based particle acceleration is presented. Here we treated the plasma as a continuous medium with an index of refraction nmn_{m} in which a single electron propagates. Because of the simplicity of this model, we did not need to perform PIC simulations in order to study the properties of the electron acceleration. We studied the properties of the electron motion due to the Lorentz force and the relativistic equations of motion were numerically solved and analysed. We compared our results to PIC simulations and experimental data. Keywords: Underdense plasma; Electron acceleration; Classical electrodynamics; Relativistic equation of motion; Ultrashort laser pulsesComment: 14 pages, 7 figures. Proceedings to the ECLIM 2014 Conference (Paris). Submitted to Laser and Particle Beams (Cambridge Journals

    Electron Acceleration by a Bichromatic Chirped Laser Pulse in Underdense Plasmas

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    A theoretical study of laser and plasma based electron acceleration is presented. An effective model has been used, in which the presence of an underdense plasma has been taken account via its index of refraction nmn_{m}. In the confines of this model, the basic phenomena can be studied by numerically solving the classical relativistic equations of motion. The key idea of this paper is the application of chirped, bichromatic laser fields. We investigated the advantages and disadvantages of mixing the second harmonic to the original λ=800nm\lambda = 800 \, \mathrm{nm} wavelength pulse. We performed calculations both for plane wave and Gaussian pulses.Comment: 6 pages, 7 figures. Proceedings to the PIPAMON (2015) conference. Submitted to NIM-B Special Issue (SI:PIPAMON-2015). Accepted for publication: 7th of October, 201

    Artificial Intelligence in the Path Planning Optimization of Mobile Agent Navigation

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    AbstractMany difficult problem solving require computational intelligence. One of the major directions in artificial intelligence consists in the development of efficient computational intelligence algorithms, like: evolutionary algorithms, and neural networks. Systems, that operate in isolation or cooperate with each other, like mobile robots could use computational intelligence algorithms for different problems/tasks solving, however in their behavior could emerge an intelligence called system's intelligence, intelligence of a system. The traveling salesman problem TSP has a large application area. It is a well-known business problem. Maximum benefits TSP, price collecting TSP have a large number of economic applications. TSP is also used in the transport logic Raja, 2012. It also has a wide range of applicability in the mobile robotic agent path planning optimization. In this paper a mobile robotic agent's path planning will be discussed, using unsupervised neural networks for the TSP solving, and from the TSP results the finding of a closely optimal path between two points in the agent's working area. In the paper a modification of the criteria function of the winner neuron selection will also be presented. At the end of the paper measurement results will be presented

    THE EFFECTIVENESS OF FAMILY CONSTELLATION THERAPY IN REDUCING PSYCHOPATHOLOGICAL SYMPTOMS IN A NATURALISTIC SETTING

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    Background: The aim of this study (ClinicalTrials.gov identifier: NCT03233958) was to provide further evidence on the effectiveness and safety of family/systemic constellation therapy, a widely used but rarely investigated form of brief group psychotherapy. Subjects and methods: Altogether, 102 individuals from the general population were followed up 1- and 6 months after their participation in the 2-day intervention. Indicators of general and problem-area-specific psychopathology, interpersonal quality of life, meaning in life, and general wellbeing were assessed. Both statistical and clinical significance were considered, and active surveillance of potential iatrogenic effects was also conducted. Results: The data showed significant improvement post-intervention in the case of the vast majority of the 17 outcome variables. At 1-month follow-up, the magnitude of improvements was typically in the moderate range. The patterns were very similar at the 6- month follow-up, suggesting that most intervention benefits were sustained in the middle term. Sensitivity analyses showed no therapist effects across the three intervention providers. Analyses into clinical significance showed that the most reliable improvements occurred in relation to interpersonal quality of life and non-diagnosis-specific psychopathology, with approximately half of the participants showing reliable improvement. Iatrogenic effects were comparable - both in terms of frequency and severity - to those reported for other forms of psychotherapy. Conclusions: Findings of the present study point toward the safety and effectiveness of family constellation therapy in reducing a variety of psychopathological symptoms (e.g., depression and anxiety) and increasing general well-being. This effectiveness is especially remarkable when considering the brevity and cost-effectiveness of the intervention

    Recent Advances Of Mucosal Capnometry And The Perspectives Of Gastrointestinal Monitoring In The Critically Ill. A Pilot Study

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    Mucosal capnometry involves the monitoring of partial pressure of carbon dioxide (PCO2) in mucous membranes. Different techniques have been developed and applied for this purpose, including sublingual or buccal sensors, or special gastrointestinal tonometric devices. The primary use of these procedures is to detect compensated shock in critically ill patients or patients undergoing major surgery. Compensatory mechanisms, in the early phases of shock, lead to the redistribution of blood flow towards the vital organs, within ostensibly typical macro-haemodynamic parameters. Unfortunately, this may result in microcirculatory disturbances, which can play a pivotal role in the development of organ failure. In such circumstances mucosal capnometry monitoring, at different gastrointestinal sites, can provide a sensitive method for the early diagnosis of shock. The special PCO2 monitoring methods assess the severity of ischaemia and help to define the necessary therapeutic interventions and testing of these monitors have justified their prognostic value. Gastrointestinal mucosal capnometry monitoring also helps in determining the severity of ischaemia and is a useful adjunctive in the diagnosis of occlusive splanchnic arterial diseases. The supplementary functional information increases the diagnostic accuracy of radiological techniques, assists in creating individualized treatment plans, and helps in follow-up the results of interventions. The results of a pilot study focusing on the interrelation of splanchnic perfusion and gastrointestinal function are given and discussed concerning recent advances in mucosal capnometry

    The role of 99mTc-DTPA retrobulbar SPECT in staging and follow-up of Graves’ orbitopathy

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    The pathogenesis of Graves’ orbitopathy (GO) is not completely understood. Coexistent hyperfunction of the thyroid gland is frequent; however, GO may also coexist with hypo- or euthyrodism. The course of GO is largely independent of thyroid function, although elevated serum TSH is known to negatively interfere with GO course. GO is severe in 10% of the cases; sight threatening complications may also develop. A successful therapy of GO requires the assesment of both the severity and activity of orbital inflammation. Based on relevant studies and our own experiences, the possible management choices are reviewed here. For this purpose, we compare the clinical value of imaging techniques for detecting the activity of the disease. During the last 15 years, we used 99mTc-DTPA retrobulbar SPECT routinely in more than 1400 patients to facilitate the right therapeutic decision. This diagnostic utility simplified management decisions compared to previously applied alternative techniques. We recommended the routine use of 99mTc-DTPA retrobulbar SPECT for the evaluation and follow-up of GO.The pathogenesis of Graves’ orbitopathy (GO) is not completely understood. Coexistent hyperfunction of the thyroid gland is frequent; however, GO may also coexist with hypo- or euthyrodism. The course of GO is largely independent of thyroid func­tion, although elevated serum TSH is known to negatively interfere with GO course. GO is severe in 10% of the cases; sight threatening complications may also develop. A successful therapy of GO requires the assesment of both the severity and activity of orbital inflammation. Based on relevant studies and our own experiences, the possible management choices are reviewed here. For this purpose, we compare the clinical value of imaging techniques for detecting the activity of the disease. During the last 15 years, we used 99mTc-DTPA retrobulbar SPECT routinely in more than 1400 patients to facilitate the right therapeutic decision. This diagnostic utility simplified management decisions compared to previously applied alternative techniques. We recommended the routine use of 99mTc-DTPA retrobulbar SPECT for the evaluation and follow-up of GO.

    The characteristics of the consumption of medicinal herbs in Hungary

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    Our research we aimed to examine a topic that has so far not been explored. In our study we analysed consumer habits related to herbs in Hungary. The national representative questionnaire involved 1050 individuals. Several multivariable statistical techniques were applied for the analysis of the data: Principal Component Analysis (PCA), cluster analysis. In our analysis we found that one third of the respondents are regular consumers. Typically, they turn to herbs for colds, flu or stomach upsets. The most popular are chamomile, rosehip, and lime flowers (consumed in the form of dried or essential oils). As a new element in our research, we studied health attitudes to the use of medicinal herbs. Based on health attitudes, we identified a total of 5 influencing factors: health awareness, sport, healthy nutrition, medical check-ups and the presence of some illness. A total of 5 clusters were defined for these factors: comprehensive regenerators, seeking objective control, comprehensive health consciousness, regenerating with food, non-users. The most important element of our conclusions is that strengthening preventive healthcare can be one of the key factors in the growth of medicinal herb consumption. Medical feedback about the state of health makes people more willing to purchase herbs. The expert recommendation as the key communication channel is an important element too
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