Optically controllable photonic structures with zero absorption

We show the possibility to periodically modulate refractive index in atomic medium in space or/and time while simultaneously keeping vanishing absorption/gain. Such modulation is based on periodic resonant enhancement of refractive index, controlled by an external optical field, and opens a way to produce coherently controllable photonic structures. We suggest possible implementation of the proposed scheme in rare-earth doped crystals with excited state absorption.Comment: 4 pages and 5 figure

Design of the VLT-CUBES image slicers: Field re-formatters to provide two spectral resolutions

CUBES is a high efficiency spectrograph designed for a Cassegrain focus of the Very Large Telescope and is expected to be in operation in 2028. It is designed to observe point or compact sources in a spectral range from 300 to 405nm. CUBES will provide two spectral resolving powers: R≥20,000 for high resolution (HR) and R≥5,000 for low resolution (LR). This is achieved by using an image slicer for each resolution mode. The image slicers re-format a rectangular on-sky field of view of either 1.5arcsec by 10arcsec (HR) or 6arcsec by 10arcsec (LR) into six side-by-side slitlets which form the spectrograph slit. The slit dimensions are 0.19mm × 88mm for HR and 0.77mm × 88mm for LR. The on-sky and physical widths of the slicer mirrors are 0.25arcsec/0.5mm (HR) and 1arcsec/2mm (LR). The image slicers reduce the spectrograph entrance slit etendue and hence the size of the spectrograph optics without associated slit losses. Each of the proposed image slicers consists of two arrays of six spherical mirrors (slicer mirror and camera mirror arrays) which provide a straight entrance slit to the spectrograph with almost diffraction-limited optical quality. This paper presents the description of the image slicers at the end of the Phase A conceptual design, including their optical design and expected performance

IMPACT OF TEHNICAL SPRAYING FACTORS ON LEAF AREA COVERAGE IN PERMANENT CROPS

Istraživanja su obavljena u vinogradu i nasadu jabuke sa dva tipa raspršivača, aksijalni (Hardi Zaturn) i radijalni (Hardi Arrow). Istraživan je utjecaj glavnih tehničkih čimbenika raspršivanja (tip mlaznice, brzina rada i norma raspršivanja) na pokrivenost tretirane površine, prosječni promjer kapljica, broja kapljica/cm2 i zanošenje tekućine. Brzina rada raspršivača podešava se na 6 i 8 km/h, a norma raspršivanja na 250, 325 i 400 l/ha za nasad jabuke te 250, 300 i 350 l/ha za vinograd. Koriste se plave (TR 8003), žute (TR 8002) i zelene (TR 80015) Lechler mlaznice. Istraživanje se postavlja kao trofaktorijalni poljski pokus sa 18 tretmana u 4 ponavljanja, kako za tip raspršivača tako i za vrstu nasada. Po tretmanu na stablo/trs postavljeno je 60 vodoosjetljivih papirića koji su obrađeni pomoću računalne analize slike i računalnog programa ImageJ. Uz glavna svojstva istraživanja utvrđuje se indeks lisne površine i gustoće, brzina i protok zračne struje, radni tlak, usmjerenje mlaznica te se prate vremenski uvjeti tijekom istraživanja. Prije samog istraživanja, raspršivači se testiraju prema europskom standardu EN 13790. Smanjivanjem ISO broja mlaznice, povećanjem brzine rada raspršivača te povećanjem norme raspršivanja povećava se pokrivenost tretirane površine, broj kapljica/cm2 i zanošenje tekućine, a smanjuje se prosječni promjer kapljica. Usporedbom dobivenih rezultata istraživanja eksploatacijom aksijalnog i radijalnog raspršivača u vinogradu i nasadu jabuke, bolje rezultate postiže radijalni raspršivač (Hardi Arrow) u oba slučaja. Najbolji odnos pokrivenosti tretirane površine i zanošenja tekućine u vinogradu ostvaruje se sa pokrivenošću tretirane površine od 64,22% i zanošenja tekućine od 17,11% (zelena mlaznica, brzina rada od 6 km/h, norma raspršivanja od 350 l/ha te radni tlak od 10,99 bar). U nasadu jabuke navedeni odnos ostvaruje se sa pokrivenošću tretirane površine od 59,55% i zanošenja tekućine od 21,10% (zelena mlaznica, brzina rada od 8 km/h, norma raspršivanja od 325 l/ha te radni tlak od 16,84 bar).Researches are conducted in vineyard and apple orchard with two different types of mist blowers, axial (Hardi Zaturn) and radial (Hardi Arrow). The influence of major technical spraying factors (type of nozzle, working speed and spray volume) were observed on coverage of the treated area, average droplet diameter, number of droplets per cm2 and drift. The working speed of sprayer was set at 6 and 8 km/h, and spray volume on 250, 325 and 400 l/ha for apple orchard and 250, 300 and 350 l/ha for vineyard. Researchers used Lechler blue (TR 8003), yellow (TR 8002) and green (TR 80015) nozzles. The research was set as three - factorial field experiment with 18 treatments in 4 repetitions, for different type of sprayer and permanent crops. We used 60 water sensitive papers for that treatment, which were processed with digital image analysis and ImageJ software. In addition to the main features of the research, research showed leaf area index and density, speed and flow of air current, working pressure, orientation of the nozzles and weather conditions, which were monitored during the study. Before the research, mist blowers are tested according to the European standard 13790. By decreasing the ISO number of nozzles and by increasing the working speed and spray volume, we found increasement of area coverage, number of droplets per cm2and drift, and decreasement of average droplet diameter. Also, by comparing the results of research exploitation by axial and radial mist blower in the vineyards and apple orchards, better results are achieved with radial mist blower (Hardi Arrow) in both cases. The best relationship of area coverage and liquid drift in vineyard were achieved with 64,22% area coverage and 17,11% of liquid drift (green nozzle, working speed of 6 km/h, spray volume of 350 l/ha, and working pressure of 10,99 bar). In apple orchard the best relationship of area coverage and liquid drift were achieved with 59,55% area coverage and 21,10% of liquid drift (green nozzle, working speed of 8 km/h, spray volume of 325 l/ha, and working pressure of 16,84 bar)

Supramolecular structural influences from remote functionality in coordination complexes of 4-picolylamine ligands

Supramolecular structural influences from remote functionality in coordination complexes of 4-picolylamine ligand

Measuring protein concentration with entangled photons

Optical interferometry is amongst the most sensitive techniques for precision measurement. By increasing the light intensity a more precise measurement can usually be made. However, in some applications the sample is light sensitive. By using entangled states of light the same precision can be achieved with less exposure of the sample. This concept has been demonstrated in measurements of fixed, known optical components. Here we use two-photon entangled states to measure the concentration of the blood protein bovine serum albumin (BSA) in an aqueous buffer solution. We use an opto-fluidic device that couples a waveguide interferometer with a microfluidic channel. These results point the way to practical applications of quantum metrology to light sensitive samples

Laser Welding of a Stent

We consider the problem of modelling the manufacture of a cylindrical Stent, in which layers of a plastic material are welded together by a Laser beam. We firstly set up the equations for this system and solve them by using a Finite Element method. We then look at various scalings which allow the equations to be simplified. The resulting equations are then solved analytically to obtain approximate solutions to the radial temperature profile and the averaged axial temperature profile

At Sea Test 2 recovery cruise : Cruise 206 on board R/V Knorr April 10 - 15, 2012 Woods Hole - Woods Hole, MA

The R/V Knorr, on Cruise 206, carried out the recovery of three moorings for the Coastal and Global Scale Nodes (CGSN) Implementing Organization of the NSF Ocean Observatories Initiative. These three moorings are prototypes of the moorings to be used by CGSN at the Pioneer, Endurance, and Global Arrays. Knorr departed from Woods Hole, Massachusetts on April 10, 2012 and steamed south to the location of the mooring deployments on the shelf break. Over five days, April 10-15, Knorr surveyed the bottom at the planned mooring sites, recovered the moorings, and carried out preliminary investigations of mechanical and electrical functionality on the recovered moorings and mooring hardware, including observations of biofouling and corrosion. Knorr returned to Woods Hole on April 15, 2012.Funding was provided by the National Science Foundation contract #SA9-10 through the Consortium for Ocean Leadershi

Where There Is No History: How to Create Trust and Connection in Learning for Transformation in Water Governance

Trust is often seen as an important element in settings of knowledge sharing and the co-creation of knowledge for dealing with transformations in water governance. However, seemingly similar conversations during a co-creation workshop in Uppsala resulted in both trust and distrust, and thereby influenced consequent possibilities for the co-creation of knowledge. Therefore, this article focuses on how trust influences knowledge sharing and how knowledge sharing influences trust. We use a case study approach to analyze the Uppsala co-creation workshop — part of the Climate Change Adaptation and Water Governance (CADWAGO) project — by comparing 25 conversations, making use of theories on swift trust and trust dynamics. We found four different conversation patterns (1) sending; (2) defending; (3) misunderstanding; and (4) connecting. The first three patterns influenced trust negatively and did not lead to knowledge sharing, whereas pattern four showed trust development and co-creation of knowledge. From our comparative analyses, we conclude that trust starts to emerge when there is mutual openness and empathy visible in turn-taking patterns. More specifically, trust emerges when communication styles allow for recognition and exploring underlying needs and wishes, resulting in a more dynamic dialogue, further trust development, and connection between actors. Our list of conversation patterns is provisional but we argue that understanding how different kinds of interactions can lead to trust or distrust is crucial to understanding why and how learning takes place—insights that are essential for fostering learning and transformations in water governance

CUBES: application of image slicers to reformat the field for two spectral resolving powers

The Cassegrain U-Band Efficient Spectrograph (CUBES) is a high-efficiency spectrograph designed for observations from 305 to 400nm. It will be integrated at a Cassegrain focus of the Very Large Telescope (VLT). The image slicer technology is applied to reformat the field of view reducing the spectrograph entrance slit etendue and minimising the spectrograph volume and weight without slit losses. Two image slicers will provide CUBES with two spectral resolving powers: R≥20,000 for high resolution (HR) and R≥5,000 for low resolution (LR). Both image slicers are composed of two arrays of six spherical mirrors. For the HR mode, a rectangular field of view of 1.5arcsec by 10arcsec is reorganised into a slit of 0.19mm × 88mm; for the LR mode, a field of view of 6arcsec by 10arcsec is reformatted into a slit of 0.77mm × 88mm, with slicer mirrors of width 0.5mm and 2mm, respectively. CUBES is currently in the Preliminary Design Phase (Phase B). This communication presents the Conceptual (Phase A) design and the main performance for the HR and LR image slicers addressing the following technological challenges: compact layout with the minimum number of optical components to optimise throughput, near diffraction limited optical quality, telecentric design with overlapped exit pupils for all slices of the field of view, distribution of the slicer mirrors to reduce shadows and selection of the best substrate for the very short wavelengths at which CUBES will operate