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Spatiotemporal sculpturing of light pulse with ultimately sophisticated structures represents a major goal of the everlasting pursue of ultra-fast information transmission and processing as well as ultra-intense energy concentration and extraction. It also holds the key to unlock new extraordinary fundamental physical effects. Traditionally, spatiotemporal light pulses are always treated as spatiotemporally separable wave packet as solution of the Maxwell’s equations. In the past decade, however, more generalized forms of spatiotemporally nonseparable solution started to emerge with growing importance for their striking physical effects. This roadmap intends to highlight the recent advances in the creation and control of increasingly complex spatiotemporally sculptured pulses, from spatiotemporally separable to complex nonseparable states, with diverse geometric and topological structures, presenting a bird’s eye viewpoint on the zoology of spatiotemporal light fields and the outlook of future trends and open challenges., SCOPUS: ar.j, info:eu-repo/semantics/published

We investigate the macroscopic physics of noncollinear high harmonic generation (HHG) at high pressures. We make the first experimental demonstration of phase matching of noncollinear high-order-difference-frequency generation at ionization fractions above the critical ionization level, which normally sets an upper limit on the achievable cutoff photon energies. Additionally, we show that noncollinear high-order-sum-frequency generation requires much higher pressures for phase matching than single-beam HHG does, which mitigates the short interaction region in this geometry. We also dramatically increase the experimentally realized cutoff energy of noncollinear circularly polarized HHG, reaching photon energies of 90 eV. Finally, we achieve complete angular separation of high harmonic orders without the use of a spectrometer.

We investigate the macroscopic physics of noncollinear high harmonic generation (HHG) at high pressures. We make the first experimental demonstration of phase matching of noncollinear high-order-difference-frequency generation at ionization fractions above the critical ionization level, which normally sets an upper limit on the achievable cutoff photon energies. Additionally, we show that noncollinear high-order-sum-frequency generation requires much higher pressures for phase matching than single-beam HHG does, which mitigates the short interaction region in this geometry. We also dramatically increase the experimentally realized cutoff energy of noncollinear circularly polarized HHG, reaching photon energies of 90 eV. Finally, we achieve complete angular separation of high harmonic orders without the use of a spectrometer.

Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

We generate angularly isolated beams of circularly polarized extreme ultraviolet light through the first implementation of non-collinear high harmonic generation with circularly polarized driving lasers. This non-collinear technique offers numerous advantages over previous methods, including the generation of higher photon energies, the separation of the harmonics from the pump beam, the production of both left and right circularly polarized harmonics at the same wavelength and the capability of separating the harmonics without using a spectrometer. To confirm the circular polarization of the beams and to demonstrate the practicality of this new light source, we measure the magnetic circular dichroism of a 20 nm iron film. Furthermore, we explain the mechanisms of non-collinear high harmonic generation using analytical descriptions in both the photon and wave models. Advanced numerical simulations indicate that this non-collinear mixing enables the generation of isolated attosecond pulses with circular polarization., Article

High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Because of reduced quantum diffusion of the radiating electron wave function, the emission from each species is highest when a short-wavelength ultraviolet driving laser is used. However, phase matching--the constructive addition of x-ray waves from a large number of atoms--favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth-limited pulse trains of ~100 attoseconds.

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

High-harmonic generation is a universal response of matter to strong femtosecond laser fields, coherently upconverting light to much shorter wavelengths. Optimizing the conversion of laser light into soft x-rays typically demands a trade-off between two competing factors. Because of reduced quantum diffusion of the radiating electron wave function, the emission from each species is highest when a short-wavelength ultraviolet driving laser is used. However, phase matching--the constructive addition of x-ray waves from a large number of atoms--favors longer-wavelength mid-infrared lasers. We identified a regime of high-harmonic generation driven by 40-cycle ultraviolet lasers in waveguides that can generate bright beams in the soft x-ray region of the spectrum, up to photon energies of 280 electron volts. Surprisingly, the high ultraviolet refractive indices of both neutral atoms and ions enabled effective phase matching, even in a multiply ionized plasma. We observed harmonics with very narrow linewidths, while calculations show that the x-rays emerge as nearly time-bandwidth-limited pulse trains of ~100 attoseconds.

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest subfemtosecond (attosecond, 10(-18) s) pulses have been produced only in the extreme UV region of the spectrum below 100 eV, which limits the range of materials and molecular systems that can be explored. Here we experimentally demonstrate a remarkable convergence of physics: when midinfrared lasers are used to drive high harmonic generation, the conditions for optimal bright, soft X-ray generation naturally coincide with the generation of isolated attosecond pulses. The temporal window over which phase matching occurs shrinks rapidly with increasing driving laser wavelength, to the extent that bright isolated attosecond pulses are the norm for 2-µm driving lasers. Harnessing this realization, we experimentally demonstrate the generation of isolated soft X-ray attosecond pulses at photon energies up to 180 eV for the first time, to our knowledge, with a transform limit of 35 attoseconds (as), and a predicted linear chirp of 300 as. Most surprisingly, advanced theory shows that in contrast with as pulse generation in the extreme UV, long-duration, 10-cycle, driving laser pulses are required to generate isolated soft X-ray bursts efficiently, to mitigate group velocity walk-off between the laser and the X-ray fields that otherwise limit the conversion efficiency. Our work demonstrates a clear and straightforward approach for robustly generating bright isolated attosecond pulses of electromagnetic radiation throughout the soft X-ray region of the spectrum.

High harmonic generation driven by femtosecond lasers makes it possible to capture the fastest dynamics in molecules and materials. However, to date the shortest subfemtosecond (attosecond, 10(-18) s) pulses have been produced only in the extreme UV region of the spectrum below 100 eV, which limits the range of materials and molecular systems that can be explored. Here we experimentally demonstrate a remarkable convergence of physics: when midinfrared lasers are used to drive high harmonic generation, the conditions for optimal bright, soft X-ray generation naturally coincide with the generation of isolated attosecond pulses. The temporal window over which phase matching occurs shrinks rapidly with increasing driving laser wavelength, to the extent that bright isolated attosecond pulses are the norm for 2-µm driving lasers. Harnessing this realization, we experimentally demonstrate the generation of isolated soft X-ray attosecond pulses at photon energies up to 180 eV for the first time, to our knowledge, with a transform limit of 35 attoseconds (as), and a predicted linear chirp of 300 as. Most surprisingly, advanced theory shows that in contrast with as pulse generation in the extreme UV, long-duration, 10-cycle, driving laser pulses are required to generate isolated soft X-ray bursts efficiently, to mitigate group velocity walk-off between the laser and the X-ray fields that otherwise limit the conversion efficiency. Our work demonstrates a clear and straightforward approach for robustly generating bright isolated attosecond pulses of electromagnetic radiation throughout the soft X-ray region of the spectrum.

We report on the analysis of the spatial beam profile of high-order harmonic radiation originating from a semi-infinite gas cell (SIGC). We experimentally assign contributions of electron trajectories to different spatial regions of the harmonic radiation beam. The angular divergence of the harmonic radiation is studied for the first time in a SIGC as a function of different phase-matching parameters. We relate the ratio of the dipole phase coefficients to the coherence time and divergence angle measurements. Simulations, including high-order-harmonic propagation, give further insight into the generation process and the influence of phase matching. The analysis reveals that the SIGC enables tuning of the cutoff frequency by altering the absorption of the generating medium. © 2013 American Physical Society.

In order to analyze the potencial effects of a financial reform aimed to provide more flexibility to Colombian Pension Funds’ regulation, this document theoretically evaluates the effects of this reform over agents’ welfare, by applying the Constant Absolute Risk Aversion (CARA) assumption and Modern Portfolio (Diversification) Theory. An empirical counterfactual exercise is used to estimate the value of pension personal account’s on the case that the foundations of this financial reform happen to be present between 1980 and 2009. Theoretical analysis suggests that individuals decrease their risk exposition according to an increase in the accumulated value in their personal accounts. In contrast, counterfactual’s exercise conclusion is that the best choice for individuals would have been to invest the whole portfolio in variable rent assets, Con el fin de analizar los posibles efectos de una reforma financiera dirigida a flexibilizar la regulacion de los Fondos de Pensiones en Colombia, este documento evalua los potenciales efectos de esta reforma sobre el bienestar de los agentes, aplicando el supuesto de individuos con funciones de utilidad con aversion absoluta al riesgo constante (CARA) y la Teorıa de Diversificacion del Portafolio. Adicionalmente se presenta un ejercicio contrafactual para estimar el valor del activo pensional si los principios de esta legislaci´on hubiesen sido aplicados en el periodo 1980-2009. Los resultados del analisis teorico sugieren que ante un mayor valor acumulado en las cuentas de pension, los individuos disminuyen su exposicion ante el riesgo en sus portafolios. Mientras que el ejercicio contrafactual indica que la mejor decision para los individuos habrıa sido invertir todo el portafolio en activos de renta variable.

In order to analyze the potencial effects of a financial reform aimed to provide more flexibility to Colombian Pension Funds’ regulation, this document theoretically evaluates the effects of this reform over agents’ welfare, by applying the Constant Absolute Risk Aversion (CARA) assumption and Modern Portfolio (Diversification) Theory. An empirical counterfactual exercise is used to estimate the value of pension personal account’s on the case that the foundations of this financial reform happen to be present between 1980 and 2009. Theoretical analysis suggests that individuals decrease their risk exposition according to an increase in the accumulated value in their personal accounts. In contrast, counterfactual’s exercise conclusion is that the best choice for individuals would have been to invest the whole portfolio in variable rent assets, Con el fin de analizar los posibles efectos de una reforma financiera dirigida a flexibilizar la regulacion de los Fondos de Pensiones en Colombia, este documento evalua los potenciales efectos de esta reforma sobre el bienestar de los agentes, aplicando el supuesto de individuos con funciones de utilidad con aversion absoluta al riesgo constante (CARA) y la Teorıa de Diversificacion del Portafolio. Adicionalmente se presenta un ejercicio contrafactual para estimar el valor del activo pensional si los principios de esta legislaci´on hubiesen sido aplicados en el periodo 1980-2009. Los resultados del analisis teorico sugieren que ante un mayor valor acumulado en las cuentas de pension, los individuos disminuyen su exposicion ante el riesgo en sus portafolios. Mientras que el ejercicio contrafactual indica que la mejor decision para los individuos habrıa sido invertir todo el portafolio en activos de renta variable.

Al següent projecte s'ha dissenyat i calculat una nau industrial per a la producció de motlles d'injecció de plàstics per a constructors d'automòbils. A la mateixa nau es donarà cabuda tant la zona productiva com l'administrativa. S'ha dimensionat els elements estructurals d'ambdós edificis i les instal•lacions d'il•luminació, electricitat, sanejament, aigua sanitària, aclimatació de l'aire i protecció contra incendis.

Introducción La nefrolitotomía percutánea (NLP) convencional utiliza derivación con nefrostomía para mejorar el drenaje de orina, facilitar la hemostasia postoperatoria y permitir un trayecto seguro para intervenciones adicionales futuras. Sin embargo, en los últimos años el procedimiento de NLP se ha modificado: ahora permite el retiro del uso del catéter de nefrostomía o de derivación urinaria, procedimiento conocido como tubeless. El presente estudio pretende evaluar la experiencia institucional en cuanto a seguridad, eficacia y ventajas de la NLP tubeless. Materiales y métodos Entre agosto de 2012 y mayo de 2014 se reclutó a 51 pacientes del Hospital Universitario San Ignacio y Clínica Fundadores para manejo con nefrolitotomía percutánea. Se incluyó a 49 pacientes con litiasis renal menor de 5cm de diámetro y mayor de 2cm con punción única o múltiple. Se aleatorizaron en 2 grupos: grupo A sin derivación (no nefrostomía no catéter doble J) 26 pacientes, grupo B con derivación (nefrostomía sonda Foley 18 Fr) 23 pacientes. Los desenlaces evaluados fueron: efectividad verificada mediante revisión de imágenes postoperatorias y definida como cálculo residual menor de 5mm, sangrado postoperatorio con medición de hemoglobina durante las primeras 24 h después de cirugía, valoración de dolor con escala visual análoga, necesidad de analgésicos durante las primeras 4 h, cantidad de rescates de analgésico durante las primeras 24 h de cirugía. Los datos se analizaron mediante el paquete estadístico IBM SPSS versión 20, utilizando estadística no paramétrica con la prueba de Wilcoxon Mann-Whitney una vez se determinó que la muestra no tenía una distribución normal. Las variables dicotómicas se analizaron utilizando la prueba de Chi2. Resultados Las características de base de los pacientes son comparables: la edad promedio en el grupo A fue de 44,73 años y en el B de 50,26 años (p=0,186), el peso en el grupo A fue de 75,96 kg y en el B de 71,96 kg (p=0,054), el tamaño de los cál

Objetivo: Evaluar las variables operatorias y de complicaciones en pacientes llevados a resección transuretral de próstata bipolar en un hospital universitario.Materiales y métodos: Estudio descriptivo de corte transversal. Revisión del registro de pacientes con hipertrofia prostática benigna del HUSI, llevados a RTUP entre el 1 de enero de 2011 al 31 de marzo de 2013. Variables demográficas; edad. Variables quirúrgicas: tiempo de resección, tiempo de cateterismo, tiempo de estancia hospitalaria. Variables de complicación: hasta 30 días del procedimiento: sangrado con requerimiento de transfusión, retención urinaria, revisión quirúrgica.Resultados: En los 27 meses se realizaron 107 RTUP, 17 con resectoscopio monopolar, 90 con bipolar, con datos completos en 85 pacientes en lo que se utilizó sistema monopolar. La edad promedio fue 67,8 años (46-85). El tiempo promedio de resección fue 69 minutos (30-120). El tiempo de catéter en la población global promedio fue 54,7 horas (19-187), y en los pacientes a quienes se les retiró la sonda antes del egreso fue 47,8 horas (19-111). Tiempo de estancia promedio 50,3 horas (23-176). Tasa de sangrado que requirió transfusión 4,7%, tasa de revisión quirúrgica 3,5%, tasa de retención urinaria 3,5%, se presentó un síndrome post-RTUP y una infección urinaria. El promedio del peso de tejido resecado fue de 25,4 (6-80). Al comparar los resultados con la serie de 2007-8, se aumentó la edad de los pacientes en 3,23 años, incremento del tiempo de resección en 11 minutos, aumento el tiempo de cateterismo en 9,3 horas, así como la estancia hospitalaria en 11,8 horas, se encuentra un aumento en la tasa de transfusión en 1,4% y de revisión quirúrgica en 1,87%. Conclusiones: El tratamiento del crecimiento prostático obstructivo con RTUP bipolar en nuestra institución ha permitido intervenir pacientes de mayor edad y con un mayor tiempo quirúrgico Las complicaciones permanecen estables en cuanto a frecuencia. Dentro del ámbito hospitalario y s