Patrones de distribución de la producción de forraje de Bromus catharticus Vahl. y B. parodii Covas et Itria

The objectives of this study were to estimate the growth rate, seasonal distribution of dry matter production and accumulated yield in five cultivars of Bromus catharticus Vahl. and one cultivar of B. parodii Covas et Itria. A secuential cuts methodology was used in a split plot design arranged in random blocks. At each cutting date dry matter yield was estimated. Growth rates were calculated for each mean date, accumulated seasonal yield was estimated and the seasonal distribution patterns were obtained. Growth rates and accumulated yield were analyzed by ANOVA and FLSD tests. B. parodii had lower initial growth rate and higher spring growth rate than B. catharticus. Differences in install growth rates and at the end of winter and beginning of spring were found among B. catharticus cultivars (p<0.05). Accumulated yield was similar for all cultivars (p>0.05).Los objetivos de este trabajo fueron obtener la tasa de crecimiento diaria, las curvas de distribución estacional de la producción de materia seca y la producción acumulada de cinco cultivares de cebadilla criolla y uno de cebadilla Intermedia. Se utilizó una metodología de cortes secuenciales en un diseño de parcelas divididas en bloques aleatorizados. En cada corte se determinó la producción de materia seca. Para cada fecha media se calcularon las tasas medias de crecimiento, la producción de materia seca acumulada y se elaboraron las curvas de distribución estacional. Las tasas medias, de crecimiento y la producción de materia seca acumulada se sometieron a análisis de varianza y prueba de diferencia mínima significativa (FLSD). Los resultados mostraron que la cebadilla intermedia tuvo menor crecimiento Inicial (p<0,05) y mayor crecimiento primaveral (p<0,05) que la cebadilla criolla. Dentro de cebadilla criolla se detectaron diferencias entre cultivares respecto del crecimiento inicial y el de fin de invierno - principios de primavera (p<0,05). No se encontraron diferencias en la producción acumulada de materia seca entre cultivares (5492 :1: 590 kgMS.ha) (p>0,05)

Peso de grano y vigor de plántula en centenos diploide y tetraploide

The objetives of this study were to determine the influence of seed weight and ploidy level on rye seedling vigor. Three seed weight and two ploidy levels were evaluated in blotting paper sandwich. Data were subjeted to analysis of variance and LSDs were calculated. Seedling vigor measured as green biomass, leaf blade length and seedling diameter increased with seed weight and ploidy level. Also the leaf blade length and coleoptile length increased with seed weight. Dry matter percentage decreased as the ploidy level increased.El objetivo del presente trabajo fue determinar el efecto del peso de grano y del nivel de ploidía sobre el vigor de plántula en centeno. Se establecieron tres categorías de peso de grano y se trabajó con dos niveles de ploidía. Se utilizaron germinadores tipo "sandwich". Se usó prueba de diferencia mínima significativa para comparación de medias. El vigor de plántula, medido por la producción de biomasa del sector aéreo, por el largo de la lámina de la primera hoja y por el diámetro de la plántula aumentó a medida que se incrementó el peso de grano y el nivel de ploidia. El largo del coleoptilo y el largo de la vaina de la primera hoja aumentaron a medida que se incrementó el peso de grano. El porcentaje de materia seca disminuyó con el incremento del nivel de ploidía pero no fue influenciado por el peso de grano

Variabilidad en Bromus brevis Nees. (cebadilla pampeana)

The objective of this study was to evaluate the variability of B. brevis Nees. Nineteen accessions were collected at different locations of La Pampa and Buenos Aires provinces and characterized in 1992 on the basis of agronomic characters. Accessions were arranged in a randomized complete block design with 3 replications. Analysis of variance and FLSD tests were performed. High variabi-lity (p<0.01) was found for seed yield, weight of 1000 anthecium, days to flowering, plant height, flag leaf length, number of spike-Iets per panicle, and panicle lenght. Significant variability (p<0.05) was also found for dry matter yield, leaf flag width, spikelet length and number of anthecium per panicle. No variability was found for internode lenght, spikelet width, number of anthecium per spikelet, awn length, fresh matter yield, and dry matter percentage. These results showed different levels of variabilily tor the agronomic characters evaluated in B. brevis.El objetivo de este trabajo fué analizar la variabilidad existente entre 19 accesiones de cebadilla pampeana (Bromus brevis Nees.) recolectadas en diferentes localidades de las provincias de La Pampa y Buenos Aires, para caracteres agronómicos, fisiológicos y morfológicos. Durante el año 1992, se realizaron dos ensayos: en uno se determinó producción de forraje y en el otro producción de semilla, caracteres de panoja y espiguilla; se midieron en total 18 variables. Para ambos ensayos se IJSÓ un diseño en bloques aleatorizados completos con tres repeticiones, Para separación de medias se utilizó la prueba DMS protegida. Se encontraron diferencias altamente significativas (p<0,01) para producción de semilla, peso de mil antecios, periodo a panojamiento, altura de planta, largo de hoja bandera, espiguillas por panoja y largo de panoja. Las diferencias fueron significativas (p<0,05) para peso seco, ancho de hoja bandera, largo de espiguilla y numero de antecios por panoja. No se halló variabilidad para largo de entrenudo, ancho de espiguilla, numero de antecios por espiguilla, largo de arista, peso verde ni para porcentaje de materia seca. Los resultados obtenidos señalan la presencia de variabilidad para caracteres de importancia desde el punto de vista forrajero

Sensing electric fields using single diamond spins

The ability to sensitively detect charges under ambient conditions would be a fascinating new tool benefitting a wide range of researchers across disciplines. However, most current techniques are limited to low-temperature methods like single-electron transistors (SET), single-electron electrostatic force microscopy and scanning tunnelling microscopy. Here we open up a new quantum metrology technique demonstrating precision electric field measurement using a single nitrogen-vacancy defect centre(NV) spin in diamond. An AC electric field sensitivity reaching ~ 140V/cm/\surd Hz has been achieved. This corresponds to the electric field produced by a single elementary charge located at a distance of ~ 150 nm from our spin sensor with averaging for one second. By careful analysis of the electronic structure of the defect centre, we show how an applied magnetic field influences the electric field sensing properties. By this we demonstrate that diamond defect centre spins can be switched between electric and magnetic field sensing modes and identify suitable parameter ranges for both detector schemes. By combining magnetic and electric field sensitivity, nanoscale detection and ambient operation our study opens up new frontiers in imaging and sensing applications ranging from material science to bioimaging

A robust, scanning quantum system for nanoscale sensing and imaging

Controllable atomic-scale quantum systems hold great potential as sensitive tools for nanoscale imaging and metrology. Possible applications range from nanoscale electric and magnetic field sensing to single photon microscopy, quantum information processing, and bioimaging. At the heart of such schemes is the ability to scan and accurately position a robust sensor within a few nanometers of a sample of interest, while preserving the sensor's quantum coherence and readout fidelity. These combined requirements remain a challenge for all existing approaches that rely on direct grafting of individual solid state quantum systems or single molecules onto scanning-probe tips. Here, we demonstrate the fabrication and room temperature operation of a robust and isolated atomic-scale quantum sensor for scanning probe microscopy. Specifically, we employ a high-purity, single-crystalline diamond nanopillar probe containing a single Nitrogen-Vacancy (NV) color center. We illustrate the versatility and performance of our scanning NV sensor by conducting quantitative nanoscale magnetic field imaging and near-field single-photon fluorescence quenching microscopy. In both cases, we obtain imaging resolution in the range of 20 nm and sensitivity unprecedented in scanning quantum probe microscopy

Resonant enhancement of the zero-phonon emission from a color center in a diamond cavity

We demonstrate coupling of the zero-phonon line of individual nitrogen-vacancy centers and the modes of microring resonators fabricated in single-crystal diamond. A zero-phonon line enhancement exceeding ten-fold is estimated from lifetime measurements at cryogenic temperatures. The devices are fabricated using standard semiconductor techniques and off-the-shelf materials, thus enabling integrated diamond photonics.Comment: 5 pages, 4 figure

Coherent, mechanical control of a single electronic spin

The ability to control and manipulate spins via electrical, magnetic and optical means has generated numerous applications in metrology and quantum information science in recent years. A promising alternative method for spin manipulation is the use of mechanical motion, where the oscillation of a mechanical resonator can be magnetically coupled to a spins magnetic dipole, which could enable scalable quantum information architectures9 and sensitive nanoscale magnetometry. To date, however, only population control of spins has been realized via classical motion of a mechanical resonator. Here, we demonstrate coherent mechanical control of an individual spin under ambient conditions using the driven motion of a mechanical resonator that is magnetically coupled to the electronic spin of a single nitrogen-vacancy (NV) color center in diamond. Coherent control of this hybrid mechanical/spin system is achieved by synchronizing pulsed spin-addressing protocols (involving optical and radiofrequency fields) to the motion of the driven oscillator, which allows coherent mechanical manipulation of both the population and phase of the spin via motion-induced Zeeman shifts of the NV spins energy. We demonstrate applications of this coherent mechanical spin-control technique to sensitive nanoscale scanning magnetometry.Comment: 6 pages, 4 figure

Enhanced Single Photon Emission from a Diamond-Silver Aperture

We have developed a scalable method for coupling single color centers in diamond to plasmonic resonators and demonstrated Purcell enhancement of the single photon emission rate of nitrogen-vacancy (NV) centers. Our structures consist of single nitrogen-vacancy (NV) center-containing diamond nanoposts embedded in a thin silver film. We have utilized the strong plasmon resonances in the diamond-silver apertures to enhance the spontaneous emission of the enclosed dipole. The devices were realized by a combination of ion implantation and top-down nanofabrication techniques, which have enabled deterministic coupling between single NV centers and the plasmonic modes for multiple devices in parallel. The plasmon-enhanced NV centers exhibited over six-fold improvements in spontaneous emission rate in comparison to bare nanoposts and up to a factor of 3.6 in radiative lifetime reduction over bulk samples, with comparable increases in photon counts. The hybrid diamond-plasmon system presented here could provide a stable platform for the implementation of diamond-based quantum information processing and magnetometry schemes.Comment: 16 pages, 4 figure

The enhanced X-ray Timing and Polarimetry mission – eXTP: an update on its scientific cases, mission profile and development status

The enhanced X-ray Timing and Polarimetry mission (eXTP) is a flagship observatory for X-ray timing, spectroscopy and polarimetry developed by an International Consortium. Thanks to its very large collecting area, good spectral resolution and unprecedented polarimetry capabilities, eXTP will explore the properties of matter and the propagation of light in the most extreme conditions found in the Universe. eXTP will, in addition, be a powerful X-ray observatory. The mission will continuously monitor the X-ray sky, and will enable multiwavelength and multi-messenger studies. The mission is currently in phase B, which will be completed in the middle of 2022

A Diamond Nanowire Single Photon Antenna

The development of a robust light source that emits one photon at a time is an outstanding challenge in quantum science and technology. Here, at the transition from many to single photon optical communication systems, fully quantum mechanical effects may be utilized to achieve new capabilities, most notably perfectly secure communication via quantum cryptography. Practical implementations place stringent requirements on the device properties, including stable photon generation, room temperature operation, and efficient extraction of many photons. Single photon light emitting devices based on fluorescent dye molecules, quantum dots, and carbon nanotube material systems have all been explored, but none have simultaneously demonstrated all criteria. Here, we describe the design, fabrication, and characterization of a bright source of single photons consisting of an individual Nitrogen-vacancy color center (NV center) in a diamond nanowire operating in ambient conditions. The nanowire plays a positive role in increasing the number of single photons collected from the NV center by an order of magnitude over devices based on bulk diamond crystals, and allows operation at an order of magnitude lower power levels. This result enables a new class of nanostructured diamond devices for room temperature photonic and quantum information processing applications, and will also impact fields as diverse as biological and chemical sensing, opto-mechanics, and scanning-probe microscopy.Comment: 16 pages, 4 figures, v2: Includes improved reference list; modified figure 1 to show a large array of NW and FDTD simulation of field profile; direct experimental comparsion of several bulk/NW devices in figure