Analyses of Groundwater for Trace Levels of Pesticides

Agricultural production is a major source of revenue in Arkansas. In order to increase productivity, it has been necessary to rely increasingly on the use of pesticides and irrigation water. In the last 15 years several states have reported finding pesticides in groundwater as a result of normal agricultural practices. Since almost half of the population also relies on groundwater as their source of drinking water, it is necessary to conduct research as to ascertain the presence or absence of commonly used pesticides in groundwater. Multi residue analytical techniques were developed for the analysis of acifluorfen, alachlor, atrazine, cyanazine, diuron, fluometuron, linuron, metolachlor and propanil from groundwater, by either GLC or HPLC. Analytical sensitivities ranged from 1 to 5 ppb. Groundwater samples were collected from three areas of southeastern Arkansas that are under heavy agricultural production. Samples were collected directly from irrigation wells just prior to and during the peak of the irrigation season and will be compared to determine whether any temporal differences exist. To-date, over 500 samples have been analyzed. No positive finding for any pesticide has been shown

Commissioning and Operation at β* = 1000m in the LHC

TUPWO050 - ISBN 978-3-95450-122-9International audienceWe have developed a special optics with a β* of 1000 m for two interaction regions (IR1 and IR5) in the LHC, to produce very low divergence beams required for elastic proton-proton scattering. We describe the design, commissioning and operation of this optics in the LHC. The β* of 1000 m was reached by de-squeezing the beams using 17 intermediate steps beyond the β* of 90 m, which had been the previous highest β* value reached in the LHC. The optics was measured and the beta beating globally corrected to a level of 10 per cent

Effects of Cooperative Learning on Performance, Attitude, and Group Behaviours in a Technical Team Environment.

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Measurement of circulating 25-hydroxyvitamin D: A historical review

The constantly increasing requests for the measurement of serum 25-hydroxyvitamin D over the last years has led reagent manufacturers to market different automated and semi-automated methods, that being unfortunately not fully harmonized, yield different results. Liquid chromatography coupled to tandem mass spectrometry (LC/MS2) has more recently been introduced. This approach allows the distinction between the two forms of 25-hydroxyvitamin D and to measure other metabolites. This approach also requires harmonization to curtail the differences between the different analytical methods. To meet this requirement, the American National Institutes of Health (NIH), the CDC (Centre for Disease Control and Prevention) in Atlanta, the NIST (National Institute of Standards and Technology) and the vitamin D Reference laboratory of Ghent University have pooled their expertise to develop a standardization program. This article reviews the main elements and the difficulties of the automated and semi-automated methods for 25-hydroxyvitamin D, from sample preparation to the analytical phase, as well as those related to mass spectrometry. It also addresses the issues related to the clinical decision thresholds and the possibility of measurements in different biological liquids

Reconstruction of source location in a network of gravitational wave interferometric detectors

This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a chi^2 minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructed one is about 1 degree. We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 degree on the source direction can be reached for 99% of the sky.Comment: Accepted in Phys. Rev.

Minimax estimation of the Wigner function in quantum homodyne tomography with ideal detectors

We estimate the quantum state of a light beam from results of quantum homodyne measurements performed on identically prepared pulses. The state is represented through the Wigner function, a ``quasi-probability density'' on $\mathbb{R}^{2}$ which may take negative values and must respect intrinsic positivity constraints imposed by quantum physics. The data consists of $n$ i.i.d. observations from a probability density equal to the Radon transform of the Wigner function. We construct an estimator for the Wigner function, and prove that it is minimax efficient for the pointwise risk over a class of infinitely differentiable functions. A similar result was previously derived by Cavalier in the context of positron emission tomography. Our work extends this result to the space of smooth Wigner functions, which is the relevant parameter space for quantum homodyne tomography.Comment: 15 page

90 m optics commissioning

http://accelconf.web.cern.ch/AccelConf/IPAC2011/papers/tupz001.pdfInternational audienceSpecial β∗ = 90 m optics have been developed for the two very high luminosity insertions of the LHC [1] [2], as a rst step to allow for very low angle precision measure- ments of the proton-proton collisions in the LHC. These optics were developed to be compatible with the stan- dard LHC injection and ramp optics. The target value of β∗ = 90 m is reached by an un-squeeze from the injection β∗ = 11 m. We report about the implementation of this op- tics and the rst experience gained in commissioning with beam during two machine studies

90m Optics Studies and Operation in the LHC

ISBN 978-3-95450-115-1 - http://accelconf.web.cern.ch/AccelConf/IPAC2012/papers/moppc006.pdfInternational audienceA high β* = 90 m optics was commissioned and used for first very forward physics operation in the LHC in 2011. The experience gained from working with this optics in 5 studies and operation periods in 2011 was very positive. The target β* = 90 m was reached by a de-squeeze from the standard 11 m injection and ramp optics on the first attempt and collisions and first physics results obtained in the second study. The optics was measured and corrected with good precision. The running conditions were very clean and allowed for measurements with roman pots very close to the beam

Performance of a thermally deformable mirror for correction of low-order aberrations in laser beams

The thermally deformable mirror is a device aiming at correcting beam-wavefront distortions for applications where classical mechanical methods are precluded by noise considerations, as in advanced gravitational wave interferometric detectors. This moderately low-cost technology can be easily implemented and controlled thanks to the good reproducibility of the actuation. By using a flexible printed circuit board technology, we demonstrate experimentally that a device of 61 actuators in thermal contact with the back surface of a high-reflective mirror is able to correct the low-order aberrations of a laser beam at 1064 nm and could be used to optimize the mode matching into Fabry-Perot cavities

PHIL photoinjector test line

LAL is now equiped with its own platform for photoinjectors tests and Research and Developement, named PHIL (PHotoInjectors at LAL). This facility has two main purposes: push the limits of the photoinjectors performances working on both the design and the associated technology and provide a low energy (MeV) short pulses (ps) electron beam for the interested users. Another very important goal of this machine will be to provide an opportunity to form accelerator physics students, working in a high technology environment. To achieve this goal a test line was realised equipped with an RF source, magnets and beam diagnostics. In this article we will desrcibe the PHIL beamline and its characteristics together with the description of the first two photoinjector realised in LAL and tested: the ALPHAX and the PHIN RF Guns