21,109 research outputs found
Experimental and Analytical Investigation of the Transonic and Supersonic Divergence Characteristics of a Delta-Plan-Form All- Movable Control
The static aeroelastic divergence characteristics of a delta-planform model of the canard control surface of a proposed air-to-ground missile have been studied both analytically and experimentally in the Mach number range from 0.6 to 3.0. The experiments indicated that divergence occurred at a nearly constant value of dynamic pressure at Mach numbers up to 1.2. At higher Mach numbers somewhat higher values of dynamic pressure were required to produce divergence. The analysis and the experiment indicate that the camber stiffness of the control surface and the stiffness of the control actuator are both important in divergence of surfaces of this type
MARKETING CHARACTERISTICS ASSOCIATED WITH SEAFOOD COUNTERS IN GROCERY STORES
This study provides a benchmark analysis of seafood counter characteristics corresponding to the peaking of per capita seafood demand in the U.S. Logistic regression results show separate seafood counters are less likely in small stores, in rural stores, and in stores in low or medium income areas. Chain stores and stores with a significant number of non-white customers were more likely to have a seafood counter. Stores in the East South Central region were less likely, and stores in New England more likely, to have a seafood counter. The likelihood that stores will develop seafood counters was related to differences in sales volume, floor space, urban/rural location, income level of clients and regional location. Continuing innovations in marketing technology of seafood counters are likely to provide expanded marketing opportunities in the future.Marketing,
Fast Single-Charge Sensing with an rf Quantum Point Contact
We report high-bandwidth charge sensing measurements using a GaAs quantum
point contact embedded in a radio frequency impedance matching circuit
(rf-QPC). With the rf-QPC biased near pinch-off where it is most sensitive to
charge, we demonstrate a conductance sensitivity of 5x10^(-6) e^(2)/h Hz^(-1/2)
with a bandwidth of 8 MHz. Single-shot readout of a proximal few-electron
double quantum dot is investigated in a mode where the rf-QPC back-action is
rapidly switched.Comment: related papers available at http://marcuslab.harvard.ed
Polarization and readout of coupled single spins in diamond
We study the coupling of a single nitrogen-vacancy center in diamond to a
nearby single nitrogen defect at room temperature. The magnetic dipolar
coupling leads to a splitting in the electron spin resonance frequency of the
nitrogen-vacancy center, allowing readout of the state of a single nitrogen
electron spin. At magnetic fields where the spin splitting of the two centers
is the same we observe a strong polarization of the nitrogen electron spin. The
amount of polarization can be controlled by the optical excitation power. We
combine the polarization and the readout in time-resolved pump-probe
measurements to determine the spin relaxation time of a single nitrogen
electron spin. Finally, we discuss indications for hyperfine-induced
polarization of the nitrogen nuclear spin
IDENTIFYING FREQUENT SEAFOOD PURCHASERS IN THE NORTHEASTERN U.S.
Factors affecting the frequency of purchase of fish and other seafood for at-home and restaurant consumption by Northeastern consumers were investigated. Cluster analysis identified six groups of consumers with similar perceptions of the attributes of fish. Demographic and cluster membership variables were employed in logistic regressions to identify the characteristics of frequent at-home use and restaurant purchasers. At-home purchase was more likely to be frequent among respondents with white collar occupations, older ages, urban/suburban and New England residence, recreational fishing participation, and membership in one of five attitudinal clusters. Restaurant purchase was more likely to be frequent among whites and among those with higher incomes, white collar occupations, recreational fishing involvement and among members of two clusters with favorable attitudes toward fish; it was less likely to be frequent in households with children age 10 and under present.Consumer/Household Economics,
Cotunneling Spectroscopy in Few-Electron Quantum Dots
Few-electron quantum dots are investigated in the regime of strong tunneling
to the leads. Inelastic cotunneling is used to measure the two-electron
singlet-triplet splitting above and below a magnetic field driven
singlet-triplet transition. Evidence for a non-equilibrium two-electron
singlet-triplet Kondo effect is presented. Cotunneling allows orbital
correlations and parameters characterizing entanglement of the two-electron
singlet ground state to be extracted from dc transport.Comment: related papers available at http://marcuslab.harvard.ed
Aquatic Vegetation, Largemouth Bass and Water Quality Responses to Low-Dose Fluridone Two Years Post Treatment
Whole-lake techniques are increasingly being used to selectively
remove exotic plants, including Eurasian watermilfoil
(
Myriophyllum spicatum
L.). Fluridone (1-methyl-3-phenyl-
5-[3-(trifluoromethyl)phenyl]-4(1
H
)-pyridinone), a systemic
whole-lake herbicide, is selective for Eurasian watermilfoil
within a narrow low concentration range. Because fluridone
applications have the potential for large effects on plant assemblages
and lake food webs, they should be evaluated at
the whole-lake scale. We examined effects of low-dose (5 to 8
ppb) fluridone applications by comparing submersed plant
assemblages, water quality and largemouth bass (
Micropterus
salmoides
) growth rates and diets between three reference
lakes and three treatment lakes one- and two-years post treatment.
In the treatment lakes, fluridone reduced Eurasian watermilfoil
cover without reducing native plant cover, although
the duration of Eurasian watermilfoil reduction varied among
treatment lakes. (PDF has 11 pages.
Rapid Single-Shot Measurement of a Singlet-Triplet Qubit
We report repeated single-shot measurements of the two-electron spin state in
a GaAs double quantum dot. The readout scheme allows measurement with fidelity
above 90% with a 7 microsecond cycle time. Hyperfine-induced precession between
singlet and triplet states of the two-electron system are directly observed, as
nuclear Overhauser fields are quasi-static on the time scale of the measurement
cycle. Repeated measurements on millisecond to second time scales reveal
evolution of the nuclear environment.Comment: supplemental material at
http://marcuslab.harvard.edu/papers/single_shot_sup.pd
Coherent spin manipulation in an exchange-only qubit
Initialization, manipulation, and measurement of a three-spin qubit are
demonstrated using a few-electron triple quantum dot, where all operations can
be driven by tuning the nearest-neighbor exchange interaction. Multiplexed
reflectometry, applied to two nearby charge sensors, allows for qubit readout.
Decoherence is found to be consistent with predictions based on gate voltage
noise with a uniform power spectrum. The theory of the exchange-only qubit is
developed and it is shown that initialization of only two spins suffices for
operation. Requirements for full multi-qubit control using only exchange and
electrostatic interactions are outlined.Comment: related work at http://marcuslab.harvard.ed
Research Notes : United States : Inheritance of metribuzin sensitivity in the soybean cultivar \u27Altona\u27
Metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] is an herbicide that can be effective in controlling many broadleaf weeds in soybeans. However, some soybean cultivars are sensitive to metribuzin and can suffer considerable damage (Wax et al., 1976). Previous research has established that a single recessive gene, hm, conditions the sensitive reaction of \u27Semmes\u27 (Edwards et al., 1976) and \u27Tracy\u27 (Kilen and Barrentine, 1983) to b metribuzin
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