6,199 research outputs found
CONSUMER HOME-USE EVALUATION OF A DEVELOPED LEAN GROUND BEEF PRODUCT
This study reports findings on the acceptance of a new lean ground beef product. Tested products involved 1) a Developed Lean product (less than 10% fat plus quality enhancers), 2) a Lean product (less than 10% fat without quality enhancers), and 3) a Market product (slightly more than 20% fat). These products were home delivered on a rotating basis to a random sample of 91 households, one product each week for three weeks. Product traits were evaluated by the household meal preparer at three stages of home use: preparing (5 traits), cooking (3 traits), and eating (4 traits), and by other household members at the final consumption stage of eating. More favorable ratings were observed for both Developed Lean and Lean products over the Market product at the preparing and cooking stages. Ratings at the eating stage were similar between the Developed Lean and the Market products indicating a favorable response to the Developed Lean product.Consumer/Household Economics,
Precision neutron interferometric measurement of the nd coherent neutron scattering length and consequences for models of three-nucleon forces
We have performed the first high precision measurement of the coherent
neutron scattering length of deuterium in a pure sample using neutron
interferometry. We find b_nd = (6.665 +/- 0.004) fm in agreement with the world
average of previous measurements using different techniques, b_nd = (6.6730 +/-
0.0045) fm. We compare the new world average for the nd coherent scattering
length b_nd = (6.669 +/- 0.003) fm to calculations of the doublet and quartet
scattering lengths from several modern nucleon-nucleon potential models with
three-nucleon force (3NF) additions and show that almost all theories are in
serious disagreement with experiment. This comparison is a more stringent test
of the models than past comparisons with the less precisely-determined nuclear
doublet scattering length of a_nd = (0.65 +/- 0.04) fm.Comment: 4 pages, 4 figure
Matroids and Quantum Secret Sharing Schemes
A secret sharing scheme is a cryptographic protocol to distribute a secret
state in an encoded form among a group of players such that only authorized
subsets of the players can reconstruct the secret. Classically, efficient
secret sharing schemes have been shown to be induced by matroids. Furthermore,
access structures of such schemes can be characterized by an excluded minor
relation. No such relations are known for quantum secret sharing schemes. In
this paper we take the first steps toward a matroidal characterization of
quantum secret sharing schemes. In addition to providing a new perspective on
quantum secret sharing schemes, this characterization has important benefits.
While previous work has shown how to construct quantum secret sharing schemes
for general access structures, these schemes are not claimed to be efficient.
In this context the present results prove to be useful; they enable us to
construct efficient quantum secret sharing schemes for many general access
structures. More precisely, we show that an identically self-dual matroid that
is representable over a finite field induces a pure state quantum secret
sharing scheme with information rate one
Fast-response free-running frequency-stabilized dc-to-dc converter employing a state plane-trajectory control law
Implementations of a state-plane-trajectory control law for energy storage dc-to-dc converters are presented. Performance characteristics of experimental voltage step-up converter systems employing these implementations are reported and compared to theoretical predictions
Constraints on a Parity-Conserving/Time-Reversal-Non-Conserving Interaction
Time-Reversal-Invariance non-conservation has now been unequivocally
demonstrated in a direct measurement at CPLEAR. What about tests of
time-reversal-invariance in systems other than the kaon system? Tests of
time-reversal-invariance belong to two classes: searches for parity violating
(P-odd)/time-reversal-invariance-odd (T-odd) interactions, and for P-even/T-odd
interactions (assuming CPT conservation this implies C-conjugation
non-conservation). Limits on a P-odd/T-odd interaction follow from measurements
of the electric dipole moment of the neutron (with a present upper limit of 6 x
10^-26 e.cm [95% C.L.]). It provides a limit on a P-odd/T-odd pion-nucleon
coupling constant which is less than 10^-4 times the weak interaction strength.
Experimental limits on a P-even/T-odd interaction are much less stringent.
Following the standard approach of describing the nucleon-nucleon interaction
in terms of meson exchanges, it can be shown that only charged rho-meson
exchange and A_1 meson exchange can lead to a P-even/T-odd interaction. The
better constraints stem from measurements of the electric dipole moment of the
neutron and from measurements of charge-symmetry breaking in neutron-proton
elastic scattering. The latter experiments were executed at TRIUMF (497 and 347
MeV) and at IUCF (183 MeV). Weak decay experiments may provide limits which
will possibly be comparable. All other experiments, like gamma decay
experiments, detailed balance experiments, polarization - analyzing power
difference determinations, and five-fold correlation experiments with polarized
incident nucleons and aligned nuclear targets, have been shown to be at least
an order of magnitude less sensitive.Comment: 15 pages LaTeX, including 5 PostScript figures. Uses ijmpe1.sty. To
appear in International Journal of Modern Physics E (IJMPE). Slight change in
short abstrac
A Microscopic T-Violating Optical Potential: Implications for Neutron-Transmission Experiments
We derive a T-violating P-conserving optical potential for neutron-nucleus
scattering, starting from a uniquely determined two-body -exchange
interaction with the same symmetry. We then obtain limits on the T-violating
-nucleon coupling from neutron-transmission
experiments in Ho. The limits may soon compete with those from
measurements of atomic electric-dipole moments.Comment: 8 pages, 2 uuencoded figures in separate files (replaces version sent
earlier in the day with figures attached), in RevTeX 3, submitted to PR
High-Sensitivity Measurement of 3He-4He Isotopic Ratios for Ultracold Neutron Experiments
Research efforts ranging from studies of solid helium to searches for a
neutron electric dipole moment require isotopically purified helium with a
ratio of 3He to 4He at levels below that which can be measured using
traditional mass spectroscopy techniques. We demonstrate an approach to such a
measurement using accelerator mass spectroscopy, reaching the 10e-14 level of
sensitivity, several orders of magnitude more sensitive than other techniques.
Measurements of 3He/4He in samples relevant to the measurement of the neutron
lifetime indicate the need for substantial corrections. We also argue that
there is a clear path forward to sensitivity increases of at least another
order of magnitude.Comment: 11 pages, 10 figure
Far-Infrared Blocked Impurity Band Detector Development
DRS Sensors & Targeting Systems, supported by detector materials supplier Lawrence Semiconductor Research Laboratory, is developing far-infrared detectors jointly with NASA Langley under the Far-IR Detector Technology Advancement Partnership (FIDTAP). The detectors are intended for spectral characterization of the Earth's energy budget from space. During the first year of this effort we have designed, fabricated, and evaluated pilot Blocked Impurity Band (BIB) detectors in both silicon and germanium, utilizing pre-existing customized detector materials and photolithographic masks. A second-year effort has prepared improved silicon materials, fabricated custom photolithographic masks for detector process, and begun detector processing. We report the characterization results from the pilot detectors and other progress
Magnetic trapping of ultracold neutrons
Three-dimensional magnetic confinement of neutrons is reported. Neutrons are
loaded into an Ioffe-type superconducting magnetic trap through inelastic
scattering of cold neutrons with 4He. Scattered neutrons with sufficiently low
energy and in the appropriate spin state are confined by the magnetic field
until they decay. The electron resulting from neutron decay produces
scintillations in the liquid helium bath that results in a pulse of extreme
ultraviolet light. This light is frequency downconverted to the visible and
detected. Results are presented in which 500 +/- 155 neutrons are magnetically
trapped in each loading cycle, consistent with theoretical predictions. The
lifetime of the observed signal, 660 s +290/-170 s, is consistent with the
neutron beta-decay lifetime.Comment: 17 pages, 18 figures, accepted for publication in Physical Review
A unified approach to combinatorial key predistribution schemes for sensor networks
There have been numerous recent proposals for key predistribution schemes for wireless sensor networks based on various types of combinatorial structures such as designs and codes. Many of these schemes have very similar properties and are analysed in a similar manner. We seek to provide a unified framework to study these kinds of schemes. To do so, we define a new, general class of designs, termed “partially balanced t-designs”, that is sufficiently general that it encompasses almost all of the designs that have been proposed for combinatorial key predistribution schemes. However, this new class of designs still has sufficient structure that we are able to derive general formulas for the metrics of the resulting key predistribution schemes. These metrics can be evaluated for a particular scheme simply by substituting appropriate parameters of the underlying combinatorial structure into our general formulas. We also compare various classes of schemes based on different designs, and point out that some existing proposed schemes are in fact identical, even though their descriptions may seem different. We believe that our general framework should facilitate the analysis of proposals for combinatorial key predistribution schemes and their comparison with existing schemes, and also allow researchers to easily evaluate which scheme or schemes present the best combination of performance metrics for a given application scenario
- …