601 research outputs found
Theory of high-order harmonic generation by an elliptically polarized laser field
We generalize a recently formulated theory of high-order harmonic generation by low-frequency laser fields [Anne L'Huillier et al., Phys. Rev. A 48, R3433 (1993)] to the case of an elliptically polarized light. Our theoretical description includes both the single-atom response and propagation. Phase matching significantly modifies the results obtained in the single-atom response. The results of our calculations, including propagation for both the intensity and polarization properties of harmonics as a function of laser ellipticity, compare very well with recent experimental observations
Total partial and electron-capture cross sections for ionization of water vapor by 20-150 keV protons
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Reply to the comment on direct experimental evidence for a negative heat capacity in the liquid to gas phase transition in hydrogen cluster ions backbending of the caloric curve
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Prevalence of electrocardiographic abnormalities in West-Asian and African male athletes
International audienceOBJECTIVES: To evaluate the electrocardiographic (ECG) characteristics of West-Asian, black and Caucasian male athletes competing in Qatar using the 2010 recommendations for 12-lead ECG interpretation by the European Society of Cardiology (ESC). DESIGN: Cardiovascular screening with resting 12-lead ECG analysis of 1220 national level athletes (800 West-Asian, 300 black and 120 Caucasian) and 135 West-Asian controls was performed. RESULTS: Ten per cent of athletes presented with 'uncommon' ECG findings. Black African descent was an independent predictor of 'uncommon' ECG changes when compared with West-Asian and Caucasian athletes (p0.05). Seven athletes (0.6%) were identified with a disease associated with sudden death; this prevalence was two times higher in black athletes than in West-Asian athletes (1% vs 0.5%), and no cases were reported in Caucasian athletes and West-Asian controls. Eighteen West-Asian and black athletes were identified with repolarisation abnormalities suggestive of a cardiomyopathy, but ultimately, none were diagnosed with a cardiac disease. CONCLUSION: West-Asian and Caucasian athletes demonstrate comparable rates of ECG findings. Black African ethnicity is positively associated with increased frequencies of 'uncommon' ECG traits. Future work should examine the genetic mechanisms behind ECG and myocardial adaptations in athletes of diverse ethnicity, aiding in the clinical differentiation between physiological remodelling and potential cardiomyopathy or ion channel disorders
Design of smart garments for sports and rehabilitation
Physical exercise has proved benefits for general health [1] and can reduce the number
of sports injuries to one third [2]. However, an athlete that has been injured during sports practice
may omit this out of fear of discrimination, and worsen the injury in the weight room, during
strength training [5]. Monitoring physiological status of an athlete or rehabilitation patients
during training may thus help the person to get an earlier intervention, preventing injuries from
getting worse. With this in mind, we propose a set of compression garments – shirt and leggings
– with textile sensors to continually monitor heart and muscle activity, breathing rate and
temperature. This paper reports the design of the garments and production of the shirt, which
comprised a 3-lead ECG system, sEMG (Surface Electromiography) electrodes and a breathing
sensor. The ECG (Electrocardiography) system was tested and presented some good results, in
particular for very even movements, but the system still needs to be improved, in order to get a
better signal, when it comes to movements with a considerable amplitude.This work is financed by Project “Deus ex Machina”, NORTE-01-0145-FEDER-000026, funded by CCDRN, through Sistema de Apoio à Investigação Cientifica e Tecnológica (Projetos Estruturados I&D&I) of Programa Operacional Regional do Norte, from Portugal 2020 and by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio
Event by event analysis of collision induced cluster ion fragmentation: sequential monomer evaporation versus fission reactions
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XUV interferometry using high-order harmonics: Application to plasma diagnostics
In this paper, we present and compare the two different XUV interferometric techniques using high-order harmonics that have been developed so far. The first scheme is based on the interference between two spatially separated phase-locked harmonic sources while the second uses two temporally separated harmonic sources. These techniques have been applied to plasma diagnostics in feasibility experiments where electron densities up to a few 1020 e[minus sign/cm3 have been measured with a temporal resolution of 200 fs. We present the main characteristics of each technique and discuss their respective potentials and limitations
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