160 research outputs found
Seaweed as food – Attitudes and preferences among Swedish consumers. A pilot study
The demand for vegetarian food is increasing and seaweeds are promising raw materials with interesting nutritional and sensory profiles. The aim of this study was to investigate the attitudes and preferences of Swedish consumers regarding seaweed as food and study differences and similarities between different consumer groups. Data from 120 adult consumers showed an overall positive attitude. More young men than women preferred seaweeds in snack products and fast food. Products containing seaweed should preferably be bought in a food store and eaten at home or in a restaurant. The most popular serving alternatives were in snacks, bread and dishes
Adolescents’ attitudes, preferences and perceived behaviours regarding healthy eating and whole grains from a gender and health interest perspective
Background: A healthy diet is important not only for the growth and development of the human body but also for the prevention of chronic diseases. However, most Swedish adolescents do not follow dietary recommen-dations, especially the intake of whole grain is very low. To create targeted conditions for healthy food choices amongst adolescents, comprehensive knowledge of factors related to adolescents’ unhealthy and healthy eating is needed. Objective: To investigate adolescents’ attitudes, preferences and perceived behaviours regarding healthy eating, with a specific focus on whole grains and to evaluate differences between genders and between adolescents with higher versus lower health interest. Design: A total of 1,178 Swedish adolescents responded to a questionnaire about their attitudes, preferences and perceived behabviours towards healthy eating and whole grains, and their general interest in nutrition and health. Results of girls and boys were compared, as well as adolescents with a higher versus lower health interest. Results: Displays information about healthy eating among adolescents and a comprehensive set of factors that may affect their ability to eat healthier. Overall, adolescents had a positive attitude towards food and health, but less than half felt that they managed to eat healthy. The consumption of different whole grain products was low, although the willingness to eat healthier and more whole grain was high. The most reported barrier to healthy eating, as well as increasing whole grain intake, was the unavailability of tasty healthy products, taste being even more important for adolescents with a low health interest than those with a high interest. Whole grain consumption and factors increasing the willingness of whole grain consumption were most prominent not only in adolescents with high health interest but also in girls compared with boys. Conclusion: The results show good potential to improve dietary habits amongst adolescents. Taste and avail-ability of healthy products were rated the most important, whilst knowledge about the products’ healthiness was rated the least important, especially amongst those with low health interest. By focusing on the attitudes and preferences of adolescents, the effectiveness may increase of initiatives to improve their dietary habits
Andreev bound states and -junction transition in a superconductor / quantum-dot / superconductor system
We study Andreev bound states and -junction transition in a
superconductor / quantum-dot / superconductor (S-QD-S) system by Green function
method. We derive an equation to describe the Andreev bound states in S-QD-S
system, and provide a unified understanding of the -junction transition
caused by three different mechanisms: (1) {\it Zeeman splitting.} For QD with
two spin levels and , we find that the surface
of the Josephson current vs the configuration of
exhibits interesting profile: a sharp peak
around ; a positive ridge in the region of
; and a {\em % negative}, flat, shallow
plain in the region of . (2){\it \
Intra-dot interaction.} We deal with the intra-dot Coulomb interaction by
Hartree-Fock approximation, and find that the system behaves as a -junction when QD becomes a magnetic dot due to the interaction. The
conditions for -junction transition are also discussed. (3) {\it \
Non-equilibrium distribution.} We replace the Fermi distribution by
a non-equilibrium one , and allow
Zeeman splitting in QD where The curves of
vs show the novel effect of interplay of
non-equilibrium distribution with magnetization in QD.Comment: 18 pages, 8 figures, Late
Nonequilibrium Josephson effect in mesoscopic ballistic multiterminal SNS junctions
We present a detailed study of nonequilibrium Josephson currents and
conductance in ballistic multiterminal SNS-devices. Nonequilibrium is created
by means of quasiparticle injection from a normal reservoir connected to the
normal part of the junction. By applying a voltage at the normal reservoir the
Josephson current can be suppressed or the direction of the current can be
reversed. For a junction longer than the thermal length, , the
nonequilibrium current increases linearly with applied voltage, saturating at a
value equal to the equilibrium current of a short junction. The conductance
exhibits a finite bias anomaly around . For symmetric
injection, the conductance oscillates -periodically with the phase
difference between the superconductors, with position of the minimum
( or ) dependent on applied voltage and temperature. For
asymmetric injection, both the nonequilibrium Josephson current and the
conductance becomes -periodic in phase difference. Inclusion of barriers
at the NS-interfaces gives rise to a resonant behavior of the total Josephson
current with respect to junction length with a period . Both
three and four terminal junctions are studied.Comment: 21 pages, 19 figures, submitted to Phys. Rev.
Interqubit coupling mediated by a high-excitation-energy quantum object
We consider a system composed of two qubits and a high-excitation-energy
quantum object used to mediate coupling between the qubits. We treat the entire
system quantum mechanically and analyze the properties of the eigenvalues and
eigenstates of the total Hamiltonian. After reproducing well-known results
concerning the leading term in the mediated coupling, we obtain an expression
for the residual coupling between the qubits in the off state. We also analyze
the entanglement between the three objects, i.e. the two qubits and the
coupler, in the eigenstates of the total Hamiltonian. Although we focus on the
application of our results to the recently realized parametric-coupling scheme
with two qubits, we also discuss extensions of our results to
harmonic-oscillator couplers, couplers that are near resonance with the qubits
and multi-qubit systems. In particular, we find that certain errors that are
absent for a two-qubit system arise when dealing with multi-qubit systems.Comment: 15 pages (two-column
Excess Noise in Biased Superconducting Weak Links
Non-equilibrium excess noise of a short quasi one-dimensional constriction
between two superconductors is considered. A general expression for the
current-current correlation function valid for arbitrary temperatures and bias
voltages is derived. This formalism is applied to a current-carrying quantum
channel with perfect transparency. Contrary to a transparent channel separating
two normal conductors, a weak link between two superconductors exhibits a
finite level of noise. The source of noise is fractional Andreev scattering of
quasiparticles with energies greater than the half-width of the
superconducting gap. For high bias voltages, , the relation
between the zero-frequency limit of the noise spectrum, , and the excess
current reads . As both the excess noise and the excess current vanish linearly in
, %, their ratio being constant.Comment: 8 pages (Latex), 1 figur
Static flux bias of a flux qubit using persistent current trapping
Qubits based on the magnetic flux degree of freedom require a flux bias,
whose stability and precision strongly affect the qubit performance, up to a
point of forbidding the qubit operation. Moreover, in the perspective of
multiqubit systems, it must be possible to flux-bias each qubit independently,
hence avoiding the traditional use of externally generated magnetic fields in
favour of on-chip techniques that minimize cross-couplings. The solution
discussed in this paper exploits a persistent current, trapped in a
superconducting circuit integrated on chip that can be inductively coupled with
an individual qubit. The circuit does not make use of resistive elements that
can be detrimental for the qubit coherence. The trapping procedure allows to
control and change stepwise the amount of stored current; after that, the
circuit can be completely disconnected from the external sources. We show in a
practical case how this works and how to drive the bias circuit at the required
value.Comment: 5 figures submitted to Superconductor Science and Technolog
Post-harvest cultivation with seafood process waters improves protein levels of Ulva fenestrata while retaining important food sensory attributes
Seaweed aquaculture can provide the growing human population with a sustainable source of proteins. Sea-based cultivation is an effective method for farming seaweeds on a large scale and can yield high biomass output. However, the quality and biochemical composition of the biomass is seasonally dependent, which limits the harvests to certain periods of the year. Here we show the possibility to extend the sea-based cultivation season of Ulva fenestrata when aiming for high protein levels, by post-harvest treatment in herring production process waters. We harvested U. fenestrata at an optimal period in terms of yield, but suboptimal in terms of protein content. We then cultivated the seaweed in onshore tank systems with the nutrient-rich process waters for 14 days. We monitored biomass yield, crude protein content, amino acid composition, and content of the health concerning metals arsenic, mercury, lead, and cadmium, as well as the sensory properties of the dried biomass. After cultivation in the process waters, biomass yields were 30 - 40% higher (210 – 230 g fresh weight) compared to in seawater (160 g fresh weight). Also, the crude protein and amino acid content increased three to five times in the process waters, reaching 12 - 17 and 15 – 21% dry weight, respectively. The protein enriched biomass followed food graded standards for heavy metal content, and consumption of the biomass does not exceed health based reference points. Additionally, no sensory attributes regarded as negative were found. This rapid, post-harvest treatment can help extend the cultivation season of sea-based seaweed farms, maximizing their output of sustainable proteins
Multilevel effects in the Rabi oscillations of a Josephson phase qubit
We present Rabi oscillation measurements of a Nb/AlOx/Nb dc superconducting
quantum interference device (SQUID) phase qubit with a 100 um^2 area junction
acquired over a range of microwave drive power and frequency detuning. Given
the slightly anharmonic level structure of the device, several excited states
play an important role in the qubit dynamics, particularly at high power. To
investigate the effects of these levels, multiphoton Rabi oscillations were
monitored by measuring the tunneling escape rate of the device to the voltage
state, which is particularly sensitive to excited state population. We compare
the observed oscillation frequencies with a simplified model constructed from
the full phase qubit Hamiltonian and also compare time-dependent escape rate
measurements with a more complete density-matrix simulation. Good quantitative
agreement is found between the data and simulations, allowing us to identify a
shift in resonance (analogous to the ac Stark effect), a suppression of the
Rabi frequency, and leakage to the higher excited states.Comment: 14 pages, 9 figures; minor corrections, updated reference
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