777 research outputs found
VALUING AMBIGUITY: THE CASE OF GENETICALLY ENGINEERED GROWTH ENHANCERS
A split-valuation method is developed and implemented to elicit the willingness to pay to consume- or avoid consuming- a product of ambiguous quality. The split-valuation method uses experimental auction markets to separate and value the positive and negative attributes of the ambiguous good. The results show that the method can be used to successfully value a good ambiguous quality. Our application reveals that for a sample of students at a midwestern land-grant institution, the average respondent is willing to pay a premium for meat produced with the use of a genetically engineered growth enhancer that has 30% to 60% fewer calories and is 10% to 20% leaner.Consumer/Household Economics,
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An investigation of South Pole HOx chemistry: Comparison of model results with ISCAT observations
Unexpected high levels of OH and NO were recorded at the South Pole (SP) Atmospheric Research Observatory during the 1998-99 ISCAT field study. Model simulations suggest a major photochemical linkage between observed OH and NO. A detailed comparison of the observations with model predictions revealed good agreement for OH at NO levels between 120 and 380 pptv. However, the model tended to overestimate OH for NO levels < 120 pptv, while it underestimated OH at levels > 380 pptv. The reasons for these deviations appear not to involve NO directly but rather HOx radical scavenging for the low NO conditions and additional HOx sources for the high NO conditions. Because of the elevated levels of NO and highly activated HOx photochemistry, the SP was found to be a strong net source of surface ozone. It is quite likely that the strong oxidizing environment found at the South Pole extends over the entire polar plateau
Dissociative recombination measurements of HCl+ using an ion storage ring
We have measured dissociative recombination of HCl+ with electrons using a
merged beams configuration at the heavy-ion storage ring TSR located at the Max
Planck Institute for Nuclear Physics in Heidelberg, Germany. We present the
measured absolute merged beams recombination rate coefficient for collision
energies from 0 to 4.5 eV. We have also developed a new method for deriving the
cross section from the measurements. Our approach does not suffer from
approximations made by previously used methods. The cross section was
transformed to a plasma rate coefficient for the electron temperature range
from T=10 to 5000 K. We show that the previously used HCl+ DR data
underestimate the plasma rate coefficient by a factor of 1.5 at T=10 K and
overestimate it by a factor of 3.0 at T=300 K. We also find that the new data
may partly explain existing discrepancies between observed abundances of
chlorine-bearing molecules and their astrochemical models.Comment: Accepted for publication in ApJ (July 7, 2013
Spectroscopy and dissociative recombination of the lowest rotational states of H3+
The dissociative recombination of the lowest rotational states of H3+ has
been investigated at the storage ring TSR using a cryogenic 22-pole
radiofrequency ion trap as injector. The H3+ was cooled with buffer gas at ~15
K to the lowest rotational levels, (J,G)=(1,0) and (1,1), which belong to the
ortho and para proton-spin symmetry, respectively. The rate coefficients and
dissociation dynamics of H3+(J,G) populations produced with normal- and para-H2
were measured and compared to the rate and dynamics of a hot H3+ beam from a
Penning source. The production of cold H3+ rotational populations was
separately studied by rovibrational laser spectroscopy using chemical probing
with argon around 55 K. First results indicate a ~20% relative increase of the
para contribution when using para-H2 as parent gas. The H3+ rate coefficient
observed for the para-H2 source gas, however, is quite similar to the H3+ rate
for the normal-H2 source gas. The recombination dynamics confirm that for both
source gases, only small populations of rotationally excited levels are
present. The distribution of 3-body fragmentation geometries displays a broad
part of various triangular shapes with an enhancement of ~12% for events with
symmetric near-linear configurations. No large dependences on internal state or
collision energy are found.Comment: 10 pages, 9 figures, to be published in Journal of Physics:
Conference Proceeding
Energy-sensitive imaging detector applied to the dissociative recombination of D2H+
We report on an energy-sensitive imaging detector for studying the
fragmentation of polyatomic molecules in the dissociative recombination of fast
molecular ions with electrons. The system is based on a large area (10 cm x 10
cm) position-sensitive, double-sided Si-strip detector with 128 horizontal and
128 vertical strips, whose pulse height information is read out individually.
The setup allows to uniquely identify fragment masses and is thus capable of
measuring branching ratios between different fragmentation channels, kinetic
energy releases, as well as breakup geometries, as a function of the relative
ion-electron energy. The properties of the detection system, which has been
installed at the TSR storage ring facility of the Max-Planck Institute for
Nuclear Physics in Heidelberg, is illustrated by an investigation of the
dissociative recombination of the deuterated triatomic hydrogen cation D2H+. A
huge isotope effect is observed when comparing the relative branching ratio
between the D2+H and the HD+D channel; the ratio 2B(D2+H)/B(HD+D), which is
measured to be 1.27 +/- 0.05 at relative electron-ion energies around 0 eV, is
found to increase to 3.7 +/- 0.5 at ~5 eV.Comment: 11 pages, 12 figures, submitted to Physical Review
EMG Biofeedback as a Tool for Simulating the Effects of Specific Leg Muscle Weakness on a Lifting Task
This study investigated the use of EMG biofeedback to simulate weakened rectus femorii and gastrocnemii muscles during the performance of a lifting task. Eight healthy women performed 15 kg free-style lifts from floor level. Three conditions were tested: unconstrained lifting, lifting with rectus femorii activity volitionally limited bilaterally through EMG biofeedback to less than 45% of maximal EMG activity, and lifting with the gastrocnemii limited to a similar level. Limiting leg muscle activity through biofeedback led to an alteration of lifting strategy, with resulting performance variables (joint angles and torques, angular velocities, center of pressure excursion, and segment coordination) comparing favorably with those from lifting trials performed by six women with moderate leg muscle weaknesses. The data indicate that EMG biofeedback can be used to simulate the effects of leg muscle weakness during these lifts, providing a new tool to study the biomechanics of muscle weakness.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45023/1/10926_2004_Article_410626.pd
Vitrine Virtual Interativa: um sistema computacional para fazer propaganda utilizando tecnologia perceptual
This paper introduces the Intel Perceptual Computing SDK as a platform to develop computer applications that provide a more compelling user experience, by changing the way people interface with computers. The interactive virtual display case is a tool that allows a potential customer to interact with the system and navigate through the product’s list by moving its hands in front a camera and executing specific hand gestures and poses
Anisotropic fragmentation in low-energy dissociative recombination
On a dense energy grid reaching up to 75 meV electron collision energy the
fragmentation angle and the kinetic energy release of neutral dissociative
recombination fragments have been studied in a twin merged beam experiment. The
anisotropy described by Legendre polynomials and the extracted rotational state
contributions were found to vary on a likewise narrow energy scale as the
rotationally averaged rate coefficient. For the first time angular dependences
higher than 2 order could be deduced. Moreover, a slight anisotropy at
zero collision energy was observed which is caused by the flattened velocity
distribution of the electron beam.Comment: 8 pages, 4 figures; The Article will be published in the proceedings
of DR 2007, a symposium on Dissociative Recombination held in Ameland, The
Netherlands (18.-23. July 2008); Reference 19 has been published meanwhile in
S. Novotny, PRL 100, 193201 (2008
Effect of Antimony and Cerium on the Formation of Chunky Graphite during Solidification of Heavy-Section Castings of Near-Eutectic Spheroidal Graphite Irons
Thermal analysis is applied to the study of the formation of chunky graphite (CHG) in heavysection castings of spheroidal graphite cast irons. To that aim, near-eutectic melts prepared in one single cast house were poured into molds containing up to four large cubic blocks 30 cm in size. Four melts have been prepared and cast that had a cerium content varying in relation with the spheroidizing alloy used. Postinoculation or addition of antimony was achieved by fixing appropriate amounts of materials in the gating system of each block. Cooling curves recorded in the center of the blocks show that solidification proceeds in three steps: a short primary deposition of graphite followed by an initial and then a bulk eutectic reaction. Formation of CHG could be unambiguously associated with increased recalescence during the bulk eutectic reaction. While antimony strongly decreases the amount of CHG, it appears that the ratio of the contents in antimony and cerium should be higher than 0.8 in order to avoid this graphite degeneracy
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