Eikonal perturbation theory in photoionization

The eikonal perturbation theory is formulated and applied to photoionization by strong laser pulses. A special emphasis is put on the first order approximation with respect to the binding potential, which is known as the generalized eikonal approximation [2015 Phys. Rev. A 91 053417]. The ordinary eikonal approximation and its domain of applicability is derived from the generalized eikonal approximation. While the former approach is singular for the electron trajectories which return to the potential center, the generalized eikonal avoids this problem. This property makes it a promising tool for further investigations of rescattering and high-order harmonic generation processes

Mercury removal in wastewater by iron oxide nanoparticles

Mercury is one of the persistent pollutants in wastewater; it is becoming a severe environmental and public health problem, this is why nowadays its removal is an obligation. Iron oxide nanoparticles are receiving much attention due to their properties, such as: great biocompatibility, ease of separation, high relation of surface-area to volume, surface modifiability, reusability, excellent magnetic properties and relative low cost. In this experiment, Fe3O4 and γ-Fe2O3 nanoparticles were synthesized using iron salts and NaOH as precipitation agents, and Aloe Vera as stabilizing agent; then these nanoparticles were characterized by three different measurements: first, using a Zetasizer Nano ZS for their size estimation, secondly UV-visible spectroscopy which showed the existence of resonance of plasmon at λmax∼360 nm, and lastly by Scanning Electron Microscopy (SEM) to determine nanoparticles form. The results of this characterization showed that the obtained Iron oxides nanoparticles have a narrow size distribution (∼100nm). Mercury removal of 70% approximately was confirmed by atomic absorption spectroscopy measurements

Evaluation of Eight Alfalfa Cultivars in a Cumulic Haplustolls of Southern Puerto Rico

Herbage and crude protein yields of 8 non-hardy alfalfa (Medicago sativa) cultivars under irrigation were evaluated at the Fortuna Agricultural Research and Development Center during 1980-1981. First year yields were excellent and ranged from 26,453 to 32,660 kg/ha in 343 days. The best performance (yield and persistence) was obtained with Hayden PX-1, Florida 66, Mesa Sirsa, and UC-163. Yields were highest during the months of April, May, and June, and lowest during August. In 1981, yields were lower and ranged from 13,060 to 19,534 kg/ha in 218 days. The cultivars with the highest forage and crude protein yields during the 10 cuttings in 1980, were also highest during the 7 cuttings in 1981. After 17 cuttings, the persistence of Mesa Sirsa, Florida 66, Tanhuato, Hayden PX-1, and UC-163 was 87, 85, 77, 76, and 65%, respectively. Mean crude protein, phosphorus, potassium, calcium, and magnesium contents for the 1980 cuttings were 21.5, 0.37, 3.44, 1.47, and 0.29%, respectively; for the 1981 cuttings, mean crude protein, phosphorus, and potassium contents were 23.2, 0.35, and 3. 11%, respectively.En el Centro de lnvestigación y Desarrollo Agrícola de Fortuna se estudiaron la productividad y la persistencia de 8 cultivares no resistentes de alfalfa por 583 días consecutivos. El suelo fue de la serie San Antón, con buen drenaje, tanto superficial como interno, y con pH 7.3. El herbicida Trifluralin (1.4 Kg/ha ingrediente activo) se incorporó a los primeros 5 cm de suelo el día anterior a la siembra. La semilla, inmediatamente después de inocularla con la cepa de bacteria apropiada, se sembró a razón de 13.5 kg/ha en surcos de 1.5 a 2.0 cm. de profundidad. Cada parcela consistió de 8 surcos a 30.5 cm de separación por 5.50 m de largo. Después de 2 meses de establecidas, las plantas se cortaron a 5 cm. de alto cada 4 a 5 semanas aproximadamente. En el 1980, se cortó 10 veces y en el 1981 7 hasta el día 6 de agosto. Generalmente, se aplicaron de 3 a 5 riegos por aspersión mensuales, dependiendo de la cantidad de lluvia. La plantación se abonó a razón de 224 y 672 kg de P y K/ha y año, respectivamente. En el 1980 se obtuvieron los siguientes rendimientos de forraje seco y proteína bruta (kg/ha): Hayden PX-1, 32,660 y 7, 135; Florida 66, 29,867 y 6,506; Mesa Sirsa, 30,547 y 6,702; UC-163, 29,224 y 6,335; UC-164, 28,194 y 5,906, Tanhuato, 26,453 y 5,548; Moapa, 27,492 y 5,830; y UC- 176 E, 27,144 y 5,906. Los rendimientos de forraje seco y proteína bruta de los 7 cortes en 1981 fueron más bajos, pero bajaron en la misma proporción que en 1980. Las cultivares más productivas durante el período de días cortos (20 de noviembre de 1980 al 18 de marzo de 1981) fueron Florida 66, Hayden PX-1, Mesa Sirsa y UC-163. El contenido medio de proteína bruta, fósforo, potasio, calcio y magnesio de las 8 cultivares en los 10 cortes del 1980 fue 21.5, 0.37, 3.44, 1.47 y 0.29%, respectivamente; el contenido medio de proteína bruta, fósforo y potasio de las 8 cultivares en los 7 cortes del 1981 fue 23.2, 0.35 t 3.11 %, respectivamente. Un nivel de potasio de 3% en los tejidos de la planta se considera adecuado para que la plantación sostenga buenos rendimientos y persistencia. Se concluye que las 4 cultivares de más alta productividad (Hayden PX- 1, Florida 66, Mesa Sirsa y UC-163) sobrepasan ampliamente la producción de 20,000 kg par hectárea y año, considerada como la mínima requerida para cultivos comerciales, y aunque la alta persistencia de la plantación de estas 4 cultivares demuestra que este cultivo puede perdurar par 2 años, o posiblemente más, en suelos aptos bajo condiciones de riego y bien administradas

Vortex Structures and Momentum Sharing in Dynamic Sauter-Schwinger Process

Vortex pattern formation in electron-positron pair creation from vacuum by a time-dependent electric field of linear polarization is analyzed. It is demonstrated that in such scenario the momentum distributions of created particles exhibit vortex-antivortex pairs. Their sensitivity to the laser field parameters such as the field frequency and intensity is also studied. Specifically, it is shown that with increasing field frequency accross the one-photon threshold additional vortex-antivortex pairs appear. Their location in the momentum space is consistent with a general threshold behavior of probability distributions of created electrons (positrons). Namely, while for small field frequencies the particles tend to be created along the field polarization direction, for large enough frequencies they are predominantly generated in the perpendicular direction. Such change in longitudinal and transverse momentum sharing of created particles occurs accross the one-photon threshold.Comment: This article belongs to the special issue of Acta Physica Polonica A printed in honor of Professor Iwo Bialynicki-Birula on the occasion of his 90th birthday (Ed. Tomasz Sowinski, DOI:10.12693/APhysPolA.143.S0

Nondipole signatures in ionization

A general method for solving numerically the time-dependent Schr\"odinger equation, that is based on the Suzuki-Trotter scheme with the split-step Fourier approach, is introduced. The method relies on a Hamiltonian decomposition, where except of the components depending exclusively on the momentum or on the position operators, there are also terms depending on both momentum and position operators in particular configurations. We demonstrate that, for as long as the latter does not depend on noncommuting coordinates of the momentum and position operators, nondipole effects in laser-matter interactions can be studied without applying extra unitary operations. Specifically, we analyze the effect of nondipole corrections in ionization of a two-dimensional hydrogen atom for low- and high-frequency pulses. In the former case, the electron wave packet dynamics is dominated by rescattering processes within the laser pulse, leading to the high-order harmonic generation. We illustrate that harmonics of even orders are generated in the direction of the laser field polarization. On the contrary, for high-frequency pulses, such rescattering processes can be neglected. We demonstrate that a significant portion of the low-energy photoelectrons is detected opposite to the laser pulse propagation direction as a consequence of their post-pulse wave packet spreading and interaction with the parent ion.Comment: 9 figure

Use of Virtual Reality and Videogames in the Physiotherapy Treatment of Stroke Patients: A Pilot Randomized Controlled Trial

© 2023 by the authors. This document is made available under the CC-BY 4.0 license http://creativecommons.org/licenses/by /4.0/ This document is the Accepted version of a Published Work that appeared in final form in International Journal of Environmental Research and Public Health. To access the final edited and published work see https:// doi.org/10.3390/ijerph20064747 AA stroke is a neurological condition with a high impact in terms of physical disability in the adult population, requiring specific and effective rehabilitative approaches. Virtual reality (VR), a technological approach in constant evolution, has great applicability in many fields of rehabilitation, including strokes. The aim of this study was to analyze the effects of a traditional neurological physiotherapy-based approach combined with the implementation of a specific VR-based program in the treatment of patients following rehabilitation after a stroke. Participants (n = 24) diagnosed with a stroke in the last six months were randomly allocated into a control group (n = 12) and an experimental group (n = 12). Both groups received one-hour sessions of neurological physiotherapy over 6 weeks, whilst the experimental group was, in addition, supplemented with VR. Patients were assessed through the Daniels and Worthingham Scale, Modified Ashworth Scale, Motor Index, Trunk Control Test, Tinetti Balance Scale, Berg Balance Scale and the Functional Ambulation Classification of the Hospital of Sagunto. Statistically significant improvements were obtained in the experimental group with respect to the control group on the Motricity Index (p = 0.005), Trunk Control Test (p = 0.008), Tinetti Balance Scale (p = 0.004), Berg Balance Scale (p = 0.007) and the Functional Ambulation Classification of the Hospital of Sagunto (p = 0.038). The use of VR in addition to the traditional physiotherapy approach is a useful strategy in the treatment of strokes