Shade and leaf retention: an aspect of effective Coffee Leaf Rust management

Coffee Leaf Rust (CLR) has been reported in over 50 coffee growing countries causing significant economic losses in Arabica coffee. The aim of this study was to determine the effect of shade on leaf life span in relation to severity of coffee leaf rust. To achieve this objective, three shade levels (shaded, partial shade, unshaded) were applied in three agro-ecological zones (AEZ) i.e. Upper-Midland (UM) I, II and III. Each treatment was replicated 4 times in 7 farms in each AEZ. All the farms had similar agronomic management levels. Infected leaves were counted per tree and disease severity was scored every month, between January and September, 2014 which is the peak period for CLR. Yields per plot were estimated using the method of Cilas and Descroix, 2004. The results showed that shaded trees retained the infected leaves 8 weeks longer than the unshaded in all the agro-ecological zones. Similarly, yield estimate from the shaded coffee (1521kg/ha clean coffee) was significantly higher than the unshaded (1050kg/ha clean coffee). Although leaves remain longer on shaded trees, allowing more time for the disease to develop and progress, severity level of shaded trees remains lower (12.8%) than unshaded (19.0%), suggesting the expression of regulation mechanism under the control of shade. Moreover, full shade generated by dense canopy, such as the one from mango or avocado tree best manages CLR across all the tested three agro-ecological zones

High-sensitivity optical measurement of mechanical Brownian motion

We describe an experiment in which a laser beam is sent into a high-finesse optical cavity with a mirror coated on a mechanical resonator. We show that the reflected light is very sensitive to small mirror displacements. We have observed the Brownian motion of the resonator with a very high sensitivity.Comment: 4 pages, 4 figures, RevTe

Selective readout and back-action reduction for wideband acoustic gravitational wave detectors

We present the concept of selective readout for broadband resonant mass gravitational wave detectors. This detection scheme is capable of specifically selecting the signal from the contributions of the vibrational modes sensitive to the gravitational waves, and efficiently rejecting the contribution from non gravitationally sensitive modes. Moreover this readout, applied to a dual detector, is capable to give an effective reduction of the back-action noise within the frequency band of interest. The overall effect is a significant enhancement in the predicted sensitivity, evaluated at the standard quantum limit for a dual torus detector. A molybdenum detector, 1 m in diameter and equipped with a wide area selective readout, would reach spectral strain sensitivities 2x10^{-23}/sqrt{Hz} between 2-6 kHz.Comment: 9 pages, 4 figure

Long-lived quantum memory with nuclear atomic spins

We propose to store non-classical states of light into the macroscopic collective nuclear spin ($10^{18}$ atoms) of a $^3$He vapor, using metastability exchange collisions. These collisions, commonly used to transfer orientation from the metastable state $2^{3}S\_1$ to the ground state state of $^3$He, can also transfer quantum correlations. This gives a possible experimental scheme to map a squeezed vacuum field state onto a nuclear spin state with very long storage times (hours).Comment: 4 page

Seeking Sustainability: COSA preliminary analysis of sustainability initiatives in the coffee sector

The growing economic value and consumer popularity of sustainability standards inevitably raise questions about the extent to which their structure and dynamics actually address many environmental, economic and public welfare issues. The Committee on Sustainable Assessment (COSA) was formed, in part, to develop a scientifically credible framework capable of assessing the impacts associated with the adoption of sustainability initiatives. This paper examines the pilot phase of vetting and testing the COSA method, an innovative management tool used to gather and analyze data using economic, environmental and social metrics.sustainability initiatives, standards, organic, fair trade, Rainforest, social, environmental, economic certification

Squeezing and entangling nuclear spins in helium 3

We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of $^3$He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically

Quantum engineering of squeezed states for quantum communication and metrology

We report the experimental realization of squeezed quantum states of light, tailored for new applications in quantum communication and metrology. Squeezed states in a broad Fourier frequency band down to 1 Hz has been observed for the first time. Nonclassical properties of light in such a low frequency band is required for high efficiency quantum information storage in electromagnetically induced transparency (EIT) media. The states observed also cover the frequency band of ultra-high precision laser interferometers for gravitational wave detection and can be used to reach the regime of quantum non-demolition interferometry. And furthermore, they cover the frequencies of motions of heavily macroscopic objects and might therefore support the attempts to observe entanglement in our macroscopic world.Comment: 12 pages, 3 figure

2D photonic-crystal optomechanical nanoresonator

We present the optical optimization of an optomechanical device based on a suspended InP membrane patterned with a 2D near-wavelength grating (NWG) based on a 2D photonic-crystal geometry. We first identify by numerical simulation a set of geometrical parameters providing a reflectivity higher than 99.8 % over a 50-nm span. We then study the limitations induced by the finite value of the optical waist and lateral size of the NWG pattern using different numerical approaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane, is used to form a compact microcavity involving the suspended nano-membrane as end mirror. The resulting cavity has a waist size smaller than 10 $\mu$m and a finesse in the 200 range. It is used to probe the Brownian motion of the mechanical modes of the nanomembrane

A micropillar for cavity optomechanics

We present a new micromechanical resonator designed for cavity optomechanics. We have used a micropillar geometry to obtain a high-frequency mechanical resonance with a low effective mass and a very high quality factor. We have coated a 60-$\mu$m diameter low-loss dielectric mirror on top of the pillar and are planning to use this micromirror as part of a high-finesse Fabry-Perot cavity, to laser cool the resonator down to its quantum ground state and to monitor its quantum position fluctuations by quantum-limited optical interferometry

Can optical squeezing be generated via polarization self-rotation in a thermal vapour cell?

The traversal of an elliptically polarized optical field through a thermal vapour cell can give rise to a rotation of its polarization axis. This process, known as polarization self-rotation (PSR), has been suggested as a mechanism for producing squeezed light at atomic transition wavelengths. In this paper, we show results of the characterization of PSR in isotopically enhanced Rubidium-87 cells, performed in two independent laboratories. We observed that, contrary to earlier work, the presence of atomic noise in the thermal vapour overwhelms the observation of squeezing. We present a theory that contains atomic noise terms and show that a null result in squeezing is consistent with this theory.Comment: 10 pages, 11 figures, submitted to PRA. Please email author for a PDF file if the article does not appear properl