4,478 research outputs found
MEASURING FOOD SAFETY PREFERENCES: IDENTIFYING CONSUMER SEGMENTS
Conjoint analysis was used to estimate individual preference functions for food safety attributes. Consumer segments were constructed by using cluster analysis to form groups which were homogeneous with respect to preferences regarding food safety. Although substantial differences existed among the three distinct groups, consumers in all segments were willing to pay a moderate amount to ensure that apples met established safety standards. However, a policy which restricts pesticide use would likely result in substantial consumer dissatisfaction, unless it could be achieved with little impact on price or quality.Food Consumption/Nutrition/Food Safety,
Fast microwave-assisted synthesis of Li-stuffed garnets and insights into Li diffusion from muon spin spectroscopy
Lithium-stuffed garnets attract huge attention due to their outstanding potential as solid-state electrolytes for lithium batteries. However, there exists a persistent challenge in the reliable synthesis of these complex functional oxides together with a lack of complete understanding of the lithium-ion diffusion mechanisms in these important materials. Addressing these issues is critical to realizing the application of garnet materials as electrolytes in all solid-state lithium-ion batteries. In this work, a cubic phase garnet of nominal composition Li6.5Al0.25La2.92Zr2O12 is synthesized through a microwave-assisted solid-state route for the first time, reducing considerably the reaction times and heating temperatures. Lithium-ion diffusion behavior is investigated by electrochemical impedance spectroscopy (EIS) and state-of-art muon spin relaxation (ÎźSR) spectroscopy, displaying activation energies of 0.55 Âą 0.03 eV and 0.19 Âą 0.01 eV respectively. This difference arises from the high inter-grain resistance, which contributes to the total resistance in EIS measurements. In contrast, ÎźSR acts as a local probe providing insights on the order of the lattice, giving an estimated value of 4.62 Ă 10â11 cm2 sâ1 for the lithium diffusion coefficient. These results demonstrate the potential of this lithium-stuffed garnet as a solid-state electrolyte for all-solid state lithium-ion batteries, an area of growing interest in the energy storage community
Possible quadrupolar nematic phase in the frustrated spin chain LiCuSbO: an NMR investigation
The frustrated one-dimensional (1D) quantum magnet LiCuSbO is one rare
realization of the spin chain model with an easily accessible
saturation field, formerly estimated to 12~T. Exotic multipolar nematic phases
were theoretically predicted in such compounds just below the saturation field,
but without unambiguous experimental observation so far. In this paper we
present extensive experimental research of the compound in the wide temperature
(30mK300K) and field (013.3T) range by muon spin rotation (SR),
Li nuclear magnetic resonance (NMR) and magnetic susceptibility (SQUID).
SR experiments in zero magnetic field demonstrate the absence of long
range 3D ordering down to 30mK. Together with former heat capacity data [S.E.
Dutton \emph{et al}, Phys. Rev. Lett. 108, 187206 (2012)], magnetic
susceptibility measurements suggest short range correlated vector chiral phase
in the field range T. In the intermediate field values (512T), the
system enters in a 3D ordered spin density wave phase with 0.75 per
copper site at lowest temperatures (125mK), estimated by NMR. At still higher
field, the magnetization is found to be saturated above 13T where the spin
lattice relaxation reveals a spin gap estimated to 3.2(2)K. We
narrow down the possibility of observing a multipolar nematic phase to the
range 12.513T.Comment: 12 pages, 15 figure
Cognitive impairment and decline in cognitively normal older adults with high amyloid-β: A meta-analysis
AbstractIntroductionThis meta-analysis aimed to characterize the nature and magnitude of amyloid (Aβ)-related cognitive impairment and decline in cognitively normal (CN) older individuals.MethodMEDLINE Ovid was searched from 2012 to June 2016 for studies reporting relationships between cerebrospinal fluid or positron emission tomography (PET) Aβ levels and cognitive impairment (cross-sectional) and decline (longitudinal) in CN older adults. Neuropsychological data were classified into domains of episodic memory, executive function, working memory, processing speed, visuospatial function, semantic memory, and global cognition. Type of Aβ measure, how Aβ burden was analyzed, inclusion of control variables, and clinical criteria used to exclude participants, were considered as moderators. Random-effects models were used for analyses with effect sizes expressed as Cohen's d.ResultsA total of 38 studies met inclusion criteria contributing 30 cross-sectional (N = 5005) and 14 longitudinal (N = 2584) samples. Aβ-related cognitive impairment was observed for global cognition (d = 0.32), visuospatial function (d = 0.25), processing speed (d = 0.18), episodic memory, and executive function (both d's = 0.15), with decline observed for global cognition (d = 0.30), semantic memory (d = 0.28), visuospatial function (d = 0.25), and episodic memory (d = 0.24). Aβ-related impairment was moderated by age, amyloid measure, type of analysis, and inclusion of control variables and decline moderated by amyloid measure, type of analysis, inclusion of control variables, and exclusion criteria used.DiscussionCN older adults with high Aβ show a small general cognitive impairment and small to moderate decline in episodic memory, visuospatial function, semantic memory, and global cognition
Control via electron count of the competition between magnetism and superconductivity in cobalt and nickel doped NaFeAs
Using a combination of neutron, muon and synchrotron techniques we show how
the magnetic state in NaFeAs can be tuned into superconductivity by replacing
Fe by either Co or Ni. Electron count is the dominant factor, since Ni-doping
has double the effect of Co-doping for the same doping level. We follow the
structural, magnetic and superconducting properties as a function of doping to
show how the superconducting state evolves, concluding that the addition of 0.1
electrons per Fe atom is sufficient to traverse the superconducting domain, and
that magnetic order coexists with superconductivity at doping levels less than
0.025 electrons per Fe atom.Comment: 4 pages, 6 figure
Identification of stable endogenous reference genes for real-time PCR in the human fetal gonad using an external standard technique
Peer reviewedPostprin
Two-gap superconductivity with line nodes in CsCaFeAsF
We report the results of a muon-spin rotation (SR) experiment to
determine the superconducting ground state of the iron-based superconductor
CsCaFeAsF with K. This compound is
related to the fully-gapped superconductor CaCsFeAs, but here the
Ca-containing spacer layer is replaced with one containing CaF. The
temperature evolution of the penetration depth strongly suggests the presence
of line nodes and is best modelled by a system consisting of both an - and a
-wave gap. We also find a potentially magnetic phase which appears below
K but does not appear to compete with the superconductivity. This
compound contains the largest alkali atom in this family of superconductors and
our results yield a value for the in-plane penetration depth of
nm.Comment: 6 pages, 2 figure
Binary black hole initial data for numerical general relativity based on post-Newtonian data
With the goal of taking a step toward the construction of astrophysically
realistic initial data for numerical simulations of black holes, we for the
first time derive a family of fully general relativistic initial data based on
post-2-Newtonian expansions of the 3-metric and extrinsic curvature without
spin. It is expected that such initial data provide a direct connection with
the early inspiral phase of the binary system. We discuss a straightforward
numerical implementation, which is based on a generalized puncture method.
Furthermore, we suggest a method to address some of the inherent ambiguity in
mapping post-Newtonian data onto a solution of the general relativistic
constraints.Comment: 13 pages, 8 figures, RevTex
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