Free Form of the Foldy-Wouthuysen Transformation in External Electromagnetic Fields

We derive the exact Foldy-Wouthuysen transformation for Dirac fermions in a time independent external electromagnetic field in the basis of the Ritus eigenfunctions, namely the eigenfunctions of the operator $(\gamma \cdot \Pi)^2$, with $\Pi^\mu = p^\mu - e A^\mu$. In this basis, the transformation acquires a free form involving the dynamical quantum numbers induced by the field.Comment: 8 pages. Accepted in J. Phys. A: Math. and Theo. (Fast Track Communication

Identification of the water stress level in olive trees during pit hardening using the trunk growth rate indicator.

Water scarcity is generating an increasing interest in deficit irrigation scheduling. The trunk diameter fluctuations are daily cycles that have been suggested as tools for irrigation scheduling. The trunk growth rate (TGR) was suggested as the best indicator for olive trees during pit hardening. The aim of this work is to clarify how the TGR could be used to identify water stress levels. The experiment was performed during the 2017 season, in a commercial, super-high-density orchard in Carmona (Seville, Spain). Four different irrigation treatments were performed according to midday stem water potential values and TGR. The data obtained were very variable and both indicators presented a wide range of water status throughout the season. The maximum trunk diameter data clearly showed the pattern of the trees water status but the comparison between treatments and the identification of the water stress level was not possible. The average TGR was linked to the midday stem water potential, but with a minimum amount of data. Irrigation scheduling based on the average TGR was difficult because of the great increases in some daily TGR values. For clarity, the pool of data was grouped by midday stem water potential. These water stress levels were characterized using the weekly frequency of TGR values. The increase of water stress reduced the frequency of values between -0.1 and 0.3mm day-1 from 60% to less than 25%. Moderate water stress levels increased the percentage of values lower than -0.3mm day-1 from 7% to 37%. The most severe water stress conditions increased the TGR values between -0.3 and -0.1mm day-1 from 16% up to 22%.IRNASINSTITUTO DE LA GRASACSI

Scatter search based met heuristic for robust optimization of the deploying of "DWDM" technology on optical networks with survivability

In this paper we discuss the application of a met heuristic approach based on the Scatter Search to deal with robust optimization of the planning problem in the deploying of the Dense Wavelength Division Multiplexing (DWDM) technology on an existing optical fiber network taking into account, in addition to the forecasted demands, the uncertainty in the survivability requirements

Sport Injuries in School and Extracurricular Activities in the Community of Madrid (Spain)

Este estudio tuvo como objetivo analizar la epidemiología lesional deportiva de las actividades desarrolladas bajo responsabilidad docente (Educación Física, recreo y actividades extraescolares) en centros de Educación Secundaria Obligatoria (ESO). Participaron 1.050 estudiantes (edad media 13,9 ± 1,3 años) que cumplimentaron un cuestionario sobre lesiones deportivas. De las 848 lesiones registradas en total, 319 (172 en chicos y 147 en chicas) ocurrieron en actividades desarrolladas bajo responsabilidad docente (0,30 lesiones/estudiante). Las actividades extraescolares fueron el ámbito con mayor promedio de lesiones (0,12 por estudiante). Se observó una mayor incidencia lesional a los 13 años y una menor probabilidad de que las lesiones ocurriesen en los chicos (OR = 0,64 (0,49-0,85); p < 0,05). Los esguinces y las contusiones fueron las lesiones más frecuentes, especialmente en tobillo y rodilla. Un 27,3% de las lesiones impidieron al alumnado participar activamente en las sesiones de Educación Física durante más de tres díasThis study aimed to analyse the epidemiology of sport injuries that occurred during activities performed under teacher supervision (Physical Education, break and extracurricular activities), at high school. A questionnaire regarding sport injuries were administered to 1050 students (mean age 13.9 ± 1.3 years). Out of the 848 sport injuries registered, 319 (172 in boys and 147 in girls) took place during activities performed under teacher supervision, (0.30 injuries/student). Extracurricular activities were the scenario in which the highest injury rate (0.12) was observed. There was a higher incidence of injury at age 13 and a lower likelihood of injuries occurring in boys (OR = 0.64 (0.49-0.85); p < 0.05). Sprains and contusions were the type of injury most frequently observed, especially in areas such as ankles and knees. A total of 27.3% of the injuries reported prevented the students from actively participating in the Physical Education sessions for more than three day

Diffusion dynamics on multiplex networks

We study the time scales associated to diffusion processes that take place on multiplex networks, i.e. on a set of networks linked through interconnected layers. To this end, we propose the construction of a supra-Laplacian matrix, which consists of a dimensional lifting of the Laplacian matrix of each layer of the multiplex network. We use perturbative analysis to reveal analytically the structure of eigenvectors and eigenvalues of the complete network in terms of the spectral properties of the individual layers. The spectrum of the supra-Laplacian allows us to understand the physics of diffusion-like processes on top of multiplex networks.Comment: 6 Pages including supplemental material. To appear in Physical Review Letter