El “Flaco” Mueller : un investigador de INTA que dejó huella

Referentes nacionales y extranjeros reconocen las contribuciones del Dr. Joaquín Mueller a la producción ovina nacional y destacan su pasión profesional, compromiso con el productor, compañerismo con sus colegas y generosidad con el prójimo. Fue pionero del mejoramiento genético de ovinos y caprinos en Argentina. Desarrolló el Servicio Nacional de Evaluación Genética Provino. Sus investigaciones fueron determinantes en la difusión de la esquila preparto y desencadenaron el afinamiento de las lanas patagónicas. Fue embajador de lujo del INTA y Argentina. Como legado formó especialistas que lo suceden con entusiasmoEstación Experimental Agropecuaria BarilocheFil: Giovannini, Nicolás. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentin

Influence of the pinhole size on the resolution of the 4Pi' microscope studied by means of the optical transfer function

Optical transfer functions are presented for the 4pi' microscope. The effects of the size of the confocal pinhole on the three-dimensional resolution are studied. It is shown that the resolution of the 4Pi' microscope depends weakly on the pinhole size. This result suggest that the pinhole can be removed in order to increase the signal-to-noise ratio

Evaluación genética caprinos criollos : Informe n°9 (incluye nacimientos 2020)

Este informe tiene como objetivo principal presentar el mérito genético de los caprinos Criollos del Norte Neuquino (CNN) candidatos al próximo servicio del Campo Anexo Pilcaniyeu (CAP) de INTA EEA Bariloche. Con la información contenida en el informe, más la inspección visual de los animales, los responsables del programa de mejoramiento genético podrán decidir los apareamientos según el tipo de progenie deseada. PARÁMETROSProCaprino. Servicio Nacional de evaluación genéticaEstación Experimental Agropecuaria BarilocheFil: Giovannini, Nicolas. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Maurino, Maria Julia. Instituto Nacional de Tecnologia Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; Argentin

Attosecond magnetization dynamics in non-magnetic materials driven by intense femtosecond lasers

Irradiating solids with ultrashort laser pulses is known to initiate femtosecond timescale magnetization dynamics. However, sub-femtosecond spin dynamics have not yet been observed or predicted. Here, we explore ultrafast light-driven spin dynamics in a highly non-resonant strong-field regime. Through state-of-the-art ab-initio calculations, we predict that a non-magnetic material can be transiently transformed into a magnetic one via dynamical extremely nonlinear spin-flipping processes, which occur on attosecond timescales and are mediated by a combination of multi-photon and spin-orbit interactions. These are non-perturbative non-resonant analogues to the inverse Faraday effect that build up from cycle-to-cycle as electrons gain angular momentum. Remarkably, we show that even for linearly polarized driving, where one does not intuitively expect any magnetic response, the magnetization transiently oscillates as the system interacts with light. This oscillating response is enabled by transverse anomalous light-driven currents in the solid, and typically occurs on timescales of ~500 attoseconds. We further demonstrate that the speed of magnetization can be controlled by tuning the laser wavelength and intensity. An experimental set-up capable of measuring these dynamics through pump-probe transient absorption spectroscopy is outlined and simulated. Our results pave the way for new regimes of ultrafast manipulation of magnetism.Comment: 21 pages, 14 figure

Are There Universal Signatures of Topological Phases in High-Harmonic Generation? Probably Not

High harmonic generation (HHG) has developed in recent years as a promising tool for ultrafast materials spectroscopy. At the forefront of these advancements, several works proposed using HHG as an all-optical probe for topology of quantum matter by identifying its signatures in the emission spectra. However, it remains unclear if such spectral signatures are indeed a robust and general approach for probing topology. To address this point, we perform a fully ab initio study of HHG from prototypical two-dimensional topological insulators in the Kane-Mele quantum spin-Hall and anomalous-Hall phases. We analyze the spectra and previously proposed topological signatures by comparing HHG from the topological and trivial phases and across the phase transition. We demonstrate and provide detailed microscopic explanations of why, in these systems, none of the observables proposed thus far uniquely and universally probes material topology. Specifically, we find that the (i) HHG helicity, (ii) anomalous HHG ellipticity, (iii) HHG elliptical dichroism, and (iv) temporal delays in HHG emission are all unreliable signatures of topological phases. Our results suggest that extreme care must be taken when interpreting HHG spectra for topological signatures and that contributions from the crystal symmetries and chemical nature might be dominant over those from topology. They hint that a truly universal topological signature in nonlinear optics is unlikely and raise important questions regarding possible utilization and detection of topology in out-of-equilibrium systems

Arrangement of a 4Pi microscope for reducing the confocal detection volume with two-photon excitation

The main advantage of two-photon fluorescence confocal microscopy is the low absorption obtained with live tissues at the wavelengths of operation. However, the resolution of two-photon fluorescence confocal microscopes is lower than in the case of one-photon excitation. The 4Pi microscope type C working in two-photon regime, in which the excitation beams are coherently superimposed and, simultaneously, the emitted beams are also coherently added, has shown to be a good solution for increasing the resolution along the optical axis and for reducing the amplitude of the side lobes of the point spread function. However, the resolution in the transverse plane is poorer than in the case of one-photon excitation due to the larger wavelength involved in the two-photon fluorescence process. In this paper we show that a particular arrangement of the 4Pi microscope, referenced as 4Pi0 microscope, is a solution for obtaining a lateral resolution in the two-photon regime similar or even better to that obtained with 4Pi microscopes working in the one-photon excitation regime

Light-Driven Extremely Nonlinear Bulk Photogalvanic Currents

We predict the generation of bulk photocurrents in materials driven by bichromatic fields that arc circularly polarized and corotating. The nonlinear photocurrents have a fully controllable directionality and amplitude without requiring carrier-envelope-phase stabilization or few-cycle pulses, and can be generated with photon energies much smaller than the band gap (reducing heating in the photoconversion process). We demonstrate with ab initio calculations that the photocurrent generation mechanism is universal and arises in gaped materials (Si, diamond, MgO, hBN), in semimetals (graphene), and in two- and three-dimensional systems. Photocurrents are shown to rely on sub-laser-cycle asymmetries in the nonlinear response that build-up coherently from cycle to cycle as the conduction band is populated. Importantly, the photocurrents are always transverse to the major axis of the co-circular lasers regardless of the material's structure and orientation (analogously to a Hall current), which we find originates from a generalized time-reversal symmetry in the driven system. At high laser powers (similar to 10(13) W/cm(2)) this symmetry can be spontaneously broken by vast electronic excitations, which is accompanied by an onset of carrier-envelope-phase sensitivity and ultrafast many-body effects. Our results are directly applicable for efficient light-driven control of electronics, and for enhancing sub-band-gap bulk photogalvanic effectsWe thank Dr. Shunsuke A. Sato for helpful discussions. We acknowledge financial support from the European Research Council (ERC-2015-AdG-694097), by the Cluster of Excellence "Advanced Imaging of Matter" (AIM), Grupos Consolidados (IT1249-19) and SFB925 "Light induced dynamics and control of correlated quantum systems." The Flatiron Institute is a division of the Simons Foundation. O. N. gratefully acknowledges the support of the Humboldt Foundatio

Vientiocho años de mejoramiento genético en una majada Merino comparada con una testigo sin selección

A los fines de demostrar progreso genético se separaron al azar dos majadas, cada una con 250 ovejas y 10 carneros, a partir de una misma población Merino del norte de la Patagonia argentina. La majada “Testigo” se mantuvo cerrada desde el servicio de 1984 hasta el servicio de 2011 con reemplazos anuales de hembras y machos elegidos al azar del propio Testigo. La majada “Núcleo” fue seleccionada por alto peso corporal (PCE), alto peso de vellón limpio (PVL) y bajo promedio de diámetro de fibras (PDF) durante un periodo de 9 años. En un segundo periodo de 8 años el Núcleo tuvo introducciones de padres de cabañas en prueba de progenie y en un tercer periodo de otros 11 años el Núcleo tuvo unas pocas introducciones de padres y fue seleccionado con énfasis en bajo PDF. El progreso genético fue calculado como la pendiente de la regresión de diferencias porcentuales en cada periodo y en el conjunto de los tres periodos. Además, se comparó la performance del Núcleo y del Testigo hacia el final de la experiencia en rasgos medidos y rasgos observados visualmente en corderos/as, borregos/as, ovejas y carneros. La tendencia genética promedio entre sexos en el primer periodo fue 0,68%, 0,31% y -0,50% para PCE, PVL y PDF, respectivamente. Estos valores se ubicaron entre el 82 y el 93% de los valores esperados teóricamente. Del primero al segundo periodo las diferencias genéticas entre Núcleo y Testigo aumentaron para PCE de 0,99 a 2,75 kg, para PVL de 0,08 a 0,27 kg y para PDF de -0,23 a -1,02 µm. Sin embargo, las diferencias no aumentaron durante el segundo periodo sugiriendo que los padres en prueba de progenie aportaron mejora genética inicial pero que no fueron siendo reemplazados por padres mejores durante el periodo. En el tercer periodo la diferencia de PDF entre majadas aumentó de -1,02 a -2,75 µm y el progreso genético en PCE, PVL y PDF durante el periodo fue sostenido. La tendencia genética en todo el ensayo fue 0,35%, 0,37% y -0,74% por año, para PCE, PVL y PDF, respectivamente. Hacia el final del experimento las diferencias entre borregos/as del Núcleo y el Testigo fueron para PCE 6,8 kg, para PVL 0,11 kg y para PDF -3,3 µm. Las respuestas correlacionadas fueron favorables para peso al destete, peso de vellón sucio y factor de confort. En ovejas las diferencias finales entre Núcleo y Testigo fueron 4,5 kg, 0,58 kg y -3,9 µm y en carneros fueron 5,4 kg, 0,66 kg y -3,5 µm para PCE, PVL y PDF, respectivamente. En borregas/os y ovejas no hubo efecto negativo sobre la resistencia a la tracción aunque en carneros el Núcleo tuvo menor resistencia a la tracción que el Testigo. Las puntuaciones visuales de suavidad, carácter, uniformidad, densidad, cabeza, cuerpo y categoría visuales fueron significativamente mayores en el Núcleo. Solo las diferencias en calidad visual de mecha y el nivel de pigmentación no resultaron significativas. El experimento demostró que es posible mejorar simultáneamente PCE, PVL y PDF. El experimento también tuvo gran impacto en la adopción del uso de mediciones para la selección de ovinos en el país.With the aim of demonstrating genetic progress two flocks, each with 250 ewes and 10 rams, were separated at random from a single Merino population of Argentina’s north Patagonia. The “Control” flock was closed from mating 1984 till mating 2011 with annual replacements of females and males selected at random from Control flock progeny. The “Nucleus” flock was selected for high body weight (PCE), high clean fleece weight (PVL) and low average fibre diameter (PDF) during a period of 9 years. In a second period of 8 years the Nucleus had introductions of stud rams on progeny test and in a third period of additional 11 years the Nucleus had a few introductions of rams and was selected with emphasis on low PDF. Genetic progress was calculated as the slope of the regression line of differences between flocks, as a percentage of the Control flock, in each period and in the three period’s altogether. In addition, towards the end of the experience the performance of Nucleus and Control lambs, hoggets, ewes and rams were compared in measured and visually scored traits. Genetic progress averaged over sexes in the first period was 0.68%, 0.31% y -0.50% for PCE, PVL and PDF, respectively. These values are within 82 and 93% of the theoretically expected values. From the first to the second period the average genetic differences between Nucleus and Control increased for PCE from 0.99 to 2.75 kg, for PVL from 0.08 to 0.27 kg and for PDF from -0.23 to -1.02 µm. The differences did not increase within the second period suggesting that rams in progeny test contributed initial improvement but were not replaced by better rams during the period. In the third period the difference in PDF between flocks increased from -1.02 to -2.75 µm and genetic progress in PCE, PVL and PDF during the period was sustained. Annual genetic progress over the full experiment resulted in 0.35%, 0.37% and -0.74% for PCE, PVL and PDF, respectively. Towards the end of the experiment the differences between Nucleus and Control hoggets was 6.8 kg for PCE, 0.11 kg for PVL and -3.3 µm for PDF. The correlated responses were favourable for weaning weight, greasy fleece weight and comfort factor. Final differences in PCE, PVL and PDF were 4.5 kg, 0.58 kg and -3.9 µm in ewes and 5.4 kg, 0.66 kg and -3.5 µm in rams, respectively. In hoggets and ewes there was no negative correlated response in staple strength but Nucleus rams had lower staple strength than Control rams. Visual scores for softness, character, uniformity, density, head, body and overall category were significantly larger in the Nucleus. Visual score differences in staple and pigmentation resulted non-significant. The experiment demonstrated that it is possible to improve PCE, PVL and PDF simultaneously. The experiment also had a large impact on the adoption of performance recording as an aid to selection of sheep in the country.EEA BarilocheFil: Mueller, Joaquin Pablo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Giovannini, Nicolas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche; ArgentinaFil: Bidinost, Franca. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Agencia de Extensión Rural Bariloche; Argentin