677 research outputs found
Survival and development of embryos of Gallus gallus domesticus treated with inorganic bromide
The range of bromide (Br-) in groundwater sources surveyed in South Africa is 0 - 18.4 mg/L. The research aimed to establish chicken embryo sensitivity to a range of Br- treatments (mg/L) injected into fertilised Ross-308 eggs in three phases: (1) five eggs injected with 10 mg Br-/L; (2) 45 eggs divided into groups and injected with 0, 1 and 5 mg Br-/L; (3) 148 eggs divided into groups injected with 0, 0.01, 0.05, 0.5, and 1 mg Br-/L. Incubation was at standard conditions. Breakout analysis was done at various stages of incubation. The mass of the embryo and of the heart, liver and brain was measured at Day 20. Statistical analysis used Statistical Analyses System® software FREQ procedure to determine the chi-square goodness-of-fit test for percentages of live or dead embryos within and between treatments. The GLM procedure was applied to test for differences in relative organ mass (g) between treatments using F-test. The results showed: (1) 10 mg Br-/L is toxic; (2) Br- is lethal to embryos at concentrations >1 mg/L and toxic at 1 mg/L; and (3) embryo survival was significantly negatively correlated (R2 = -0.92) with increasing Br- concentrations. Concentrations >0.5 mg Br-/L showed greater risk on differential development. Concentrations >0.01 mg Br-/L showed potentially severe effects on developing embryos. The heart showed the greatest relative growth response followed by the brain. The no observed adverse effect level target water quality range (NOAEL-TWQR) in developing chicken embryos was 0 - 0.01 mg/L.Keywords: Bromine, embryo model, halogens, maximum residue level, toxicity, water qualit
Qualification Tests of 474 Photomultiplier Tubes for the Inner Detector of the Double Chooz Experiment
The hemispherical 10" photomultiplier tube (PMT) R7081 from Hamamatsu
Photonics K.K. (HPK) is used in various experiments in particle and
astroparticle physics. We describe the test and calibration of 474 PMTs for the
reactor antineutrino experiment Double Chooz. The unique test setup at
Max-Planck-Institut f\"ur Kernphysik Heidelberg (MPIK) allows one to calibrate
30 PMTs simultaneously and to characterize the single photo electron response,
transit time spread, linear behaviour and saturation effects, photon detection
efficiency and high voltage calibration
Qualification Tests of 474 Photomultiplier Tubes for the Inner Detector of the Double Chooz Experiment
The hemispherical 10" photomultiplier tube (PMT) R7081 from Hamamatsu
Photonics K.K. (HPK) is used in various experiments in particle and
astroparticle physics. We describe the test and calibration of 474 PMTs for the
reactor antineutrino experiment Double Chooz. The unique test setup at
Max-Planck-Institut f\"ur Kernphysik Heidelberg (MPIK) allows one to calibrate
30 PMTs simultaneously and to characterize the single photo electron response,
transit time spread, linear behaviour and saturation effects, photon detection
efficiency and high voltage calibration
Qualification Tests of 474 Photomultiplier Tubes for the Inner Detector of the Double Chooz Experiment
The hemispherical 10" photomultiplier tube (PMT) R7081 from Hamamatsu
Photonics K.K. (HPK) is used in various experiments in particle and
astroparticle physics. We describe the test and calibration of 474 PMTs for the
reactor antineutrino experiment Double Chooz. The unique test setup at
Max-Planck-Institut f\"ur Kernphysik Heidelberg (MPIK) allows one to calibrate
30 PMTs simultaneously and to characterize the single photo electron response,
transit time spread, linear behaviour and saturation effects, photon detection
efficiency and high voltage calibration
Sums of products of Ramanujan sums
The Ramanujan sum is defined as the sum of -th powers of the
primitive -th roots of unity. We investigate arithmetic functions of
variables defined as certain sums of the products
, where are polynomials with
integer coefficients. A modified orthogonality relation of the Ramanujan sums
is also derived.Comment: 13 pages, revise
Recommended from our members
Closing the loop: Reconnecting human dynamics to Earth System science
International commitment to the appropriately ambitious Paris climate agreement and the United Nations Sustainable Development Goals in 2015 has pulled into the limelight the urgent need for major scientific progress in understanding and modelling the Anthropocene, the tightly intertwined social-environmental planetary system that humanity now inhabits. The Anthropocene qualitatively differs from previous eras in Earth’s history in three key characteristics: (1) There is planetary-scale human agency. (2) There are social and economic networks of teleconnections spanning the globe. (3) It is dominated by planetary-scale social-ecological feedbacks. Bolting together old concepts and methodologies cannot be an adequate approach to describing this new geological era. Instead, we need a new paradigm in Earth System science that is founded equally on a deep understanding of the physical and biological Earth System – and of the economic, social and cultural forces that are now an intrinsic part of it. It is time to close the loop and bring socially mediated dynamics explicitly into theory, analysis and models that let us study the whole Earth System
Lithium and aluminium carbamato derivatives of the utility amide 2, 2, 6, 6- tetramethylpiperidide
Insertion of CO2 into the metal-N bond of a series of synthetically-important alkali-metal TMP (2,2,6,6-tetramethylpiperidide) complexes has been studied. Determined by X-ray crystallography, the molecular structure of the TMEDA-solvated Li derivative shows a central 8-membered (LiOCO)2 ring lying in a chair conformation with distorted tetrahedral lithium centres. While trying to obtain crystals of a THF solvated derivative, a mixed carbonato/carbamato dodecanuclear lithium cluster was formed containing two central (CO3)2- fragments and eight O2CTMP ligands with four distinct bonding modes. A bisalkylaluminium carbamato complex has also been prepared via two different methods (CO2 insertion into a pre-formed Al-N bond and ligand transfer from the corresponding lithium reagent) which adopts a dimeric structure in the solid state
Spectral line shape of resonant four-wave mixing induced by broad-bandwidth lasers
We present a theoretical and experimental study of the line shape of resonant four-wave mixing induced by broad-bandwidth laser radiation that revises the theory of Meacher, Smith, Ewart, and Cooper (MSEC) [Phys. Rev. A 46, 2718 (1992)]. We adopt the same method as MSEC but correct for an invalid integral used to average over the distribution of atomic velocities. The revised theory predicts a Voigt line shape composed of a homogeneous, Lorentzian component, defined by the collisional rate Γ, and an inhomogeneous, Doppler component, which is a squared Gaussian. The width of the inhomogeneous component is reduced by a factor of √2 compared to the simple Doppler width predicted by MSEC. In the limit of dominant Doppler broadening, the width of the homogeneous component is predicted to be 4Γ, whereas in the limit of dominant homogeneous broadening, the predicted width is 2Γ. An experimental measurement is reported of the line shape of the four-wave-mixing signal using a broad-bandwidth, "modeless", laser resonant with the Q1 (6) line of the A2 Σ - X2 Π(0,0) system of the hydroxyl radical. The measured widths of the Voigt components were found to be consistent with the predictions of the revised theory
Prewetting transitions of Ar and Ne on alkali metal surfaces
We have studied by means of Density-Functional calculations the wetting
properties of Ar and Ne adsorbed on a plane whose adsorption properties
simulate the Li and Na surfaces. We use reliable ab-initio potentials to model
the gas-substrate interactions. Evidence for prewetting transitions is found
for all the systems investigated and their wetting phase diagrams are
calculated.Comment: 6 pages, 8 figures, submitted for publication in Phys. Rev.
Detailed investigation of the superconducting transition of niobium disks exhibiting the paramagnetic Meissner effect
The superconducting transition region in a Nb disk showing the paramagnetic
Meissner effect (PME) has been investigated in detail. From the field-cooled
magnetization behavior, two well-defined temperatures can be associated with
the appearance of the PME: T_1 (< T_c) indicates the characteristic temperature
where the paramagnetic moment first appears and a lower temperature T_p (< T_1)
defines the temperature where the positive moment no longer increases. During
the subsequent warming, the paramagnetic moment begins to decrease at T_p and
then vanishes at T_1 with the magnitude of the magnetization change between
these two temperatures being nearly the same as that during cooling. This
indicates that the nature of the PME is reversible and not associated with flux
motion. Furthermore, the appearance of this paramagnetic moment is even
observable in fields as large as 0.2 T even though the magnetization does not
remain positive to the lowest temperatures. Magnetic hysteresis loops in the
temperature range between T_1 and T_p also exhibit a distinct shape that is
different from the archetypal shape of a bulk type-II superconductor. These
behaviors are discussed in terms of the so-called 'giant vortex state'.Comment: Total 4 printed pages, 4 Figure
- …