4,494 research outputs found
Difference L operators and a Casorati determinant solution to the T-system for twisted quantum affine algebras
We propose factorized difference operators L(u) associated with the twisted
quantum affine algebras U_{q}(A^{(2)}_{2n}),U_{q}(A^{(2)}_{2n-1}),
U_{q}(D^{(2)}_{n+1}),U_{q}(D^{(3)}_{4}). These operators are shown to be
annihilated by a screening operator. Based on a basis of the solutions of the
difference equation L(u)w(u)=0, we also construct a Casorati determinant
solution to the T-system for U_{q}(A^{(2)}_{2n}),U_{q}(A^{(2)}_{2n-1}).Comment: 15 page
The Quantum Nature of a Nuclear Phase Transition
In their ground states, atomic nuclei are quantum Fermi liquids. At finite
temperatures and low densities, these nuclei may undergo a phase change similar
to, but substantially different from, a classical liquid gas phase transition.
As in the classical case, temperature is the control parameter while density
and pressure are the conjugate variables. At variance with the classical case,
in the nucleus the difference between the proton and neutron concentrations
acts as an additional order parameter, for which the symmetry potential is the
conjugate variable. Different ratios of the neutron to proton concentrations
lead to different critical points for the phase transition. This is analogous
to the phase transitions occurring in He-He liquid mixtures. We
present experimental results which reveal the N/Z dependence of the phase
transition and discuss possible implications of these observations in terms of
the Landau Free Energy description of critical phenomena.Comment: 5 pages, 4 figure
Waxy starch to replace vegetable fat in extruded snack aromatisation and different salt delivery way to decrease sodium intake
Food industries must adapt their formulations to consumer needs, for a healthy diet. Extruded snacks are
products where 10 to 20 % of fat, and large amounts of salt, are sprinkled on to fix flavours. Considering the
need for flavouring and simultaneously reducing fat and sodium on snacks, an alternative flavouring method
based on polysaccharides and a different salt delivery method was studied. This work aimed to evaluate waxy
starch solutions to replace the oil in snacks, and a different approach to deliver salt, decreasing sodium
content while keeping the same salt perception. To change the salt level, agglomerates were made with 70 %,
and 85 % salt amounts, 30 % and 15 % starch added, respectively, in three different treatments, T1 (70 % of
salt), T2 (85 % of salt), and T3 (100 % of salt, without waxy starch) as a control sample. All samples were
milled in the same granulometry as regular salt. The snacks were flavoured using coatings consisting of waxywater
solutions. The products were analysed by evaluating: i) physical-chemical parameters (lipids and
sodium content, agglomeration index analysis (IA), and colour); ii) instrumental hardness; iii) sensorial
parameters with 52 non-trained tasters. The main results showed no significant differences between T1, T2,
and control samples in terms of lipids, sensorial perception, colour, and texture. As expected, in the sodium
content, 30 % of reduction were found in T1 and 15 % of reduction in T2 compared with control. In this
context, snacks produced in the present study would be healthier without a significant saltness perception
difference from the controlsinfo:eu-repo/semantics/publishedVersio
Upper critical field, lower critical field and critical current density of FeTe0.60Se0.40 single crystal
The transport and magnetic studies are performed on high quality
FeTe0.60Se0.40 single crystals to determine the upper critical fields (Hc2),
lower critical field (Hc1) and the Critical current density (Jc). The value of
upper critical field Hc2 are very large, whereas the activation energy as
determined from the slope of the Arrhenius plots are was found to be lower than
that in the FeAs122 superconductor. The lower critical field was determined in
ab direction and c direction of the crystal, and was found to have a anisotropy
of 'gamma'{=(Hc1//c) / (Hc1//b)} ~ 4. The magnetic isotherms measured up to 12
Tesla shows the presence of fishtail behavior. The critical current densities
at 1.8K of the single crystal was found to almost same in both ab and c
direction as 1X105 Amp/cm2 in low field regime.Comment: 9 pages, 6 figure
Effects of Disorder in FeSe : An Ab Initio Study
Using the coherent-potential approximation, we have studied the effects of
excess Fe, Se-deficiency, and substitutions of S, Te on Se sub-lattice and Co,
Ni and Cu on Fe sub-lattice in FeSe. Our results show that (i) a small amount
of excess Fe substantially disorders the Fe-derived bands while Se-deficiency
affects mainly the Se-derived bands, (ii) the substitution of S or Te enhances
the possibility of Fermi surface nesting, specially in FeSeTe,
in spite of disordering the Se-derived bands, (iii) the electron doping through
Co, Ni or Cu disorders the system and pushes down the Fe-derived bands, thereby
destroying the possibility of Fermi surface nesting. A comparison of these
results with the rigid-band, virtual-crystal and supercell approximations
reveals the importance of describing disorder with the coherent-potential
approximation.Comment: Redone VCA calculations, and some minor changes. (Accepted for
publication in Journal of Physics:Condensed Matter
Curie temperature enhancement of electron doped SrFeMoO perovskites studied by photoemission spectroscopy
We report here on the electronic structure of electron-doped half-metallic
ferromagnetic perovskites such SrLaFeMoO (=0-0.6) as
obtained from high-resolved valence-band photoemission spectroscopy (PES). By
comparing the PES spectra with band structure calculations, a distinctive peak
at the Fermi level (E) with predominantly (Fe+Mo) t
character has been evidenced for all samples, irrespectively of the values
investigated. Moreover, we show that the electron doping due to the La
substitution provides selectively delocalized carriers to the
t metallic spin channel. Consequently, a gradual rising of
the density of states at the E has been observed as a function of the La
doping. By changing the incoming photon energy we have shown that electron
doping mainly rises the density of states of Mo parentage. These findings
provide fundamental clues for understanding the origin of ferromagnetism in
these oxides and shall be of relevance for tailoring oxides having still higher
T
Difference L operators related to q-characters
We introduce a factorized difference operator L(u) annihilated by the
Frenkel-Reshetikhin screening operator for the quantum affine algebra
U_q(C^{(1)}_n). We identify the coefficients of L(u) with the fundamental
q-characters, and establish a number of formulas for their higher analogues.
They include Jacobi-Trudi and Weyl type formulas, canceling tableau sums,
Casorati determinant solution to the T-system, and so forth. Analogous
operators for the orthogonal series U_q(B^{(1)}_n) and U_q(D^{(1)}_n) are also
presented.Comment: 25 pages, LaTeX2e, no figur
Search for Radiative Decays of Cosmic Background Neutrino using Cosmic Infrared Background Energy Spectrum
We propose to search for the neutrino radiative decay by fitting a photon
energy spectrum of the cosmic infrared background to a sum of the photon energy
spectrum from the neutrino radiative decay and a continuum. By comparing the
present cosmic infrared background energy spectrum observed by AKARI and
Spitzer to the photon energy spectrum expected from neutrino radiative decay
with a maximum likelihood method, we obatined a lifetime lower limit of to years at 95% confidence level for the
third generation neutrino in the mass range between 50 \mmev
and 150 \mmev under the present constraints by the neutrino oscillation
measurements. In the left-right symmetric model, the minimum lifetime of
is predicted to be years for of 50 \mmev. We
studied the feasibility of the observation of the neutrino radiative decay with
a lifetime of years, by measuring a continuous energy
spectrum of the cosmic infrared background
Techniques for Arbuscular Mycorrhiza Inoculum Reduction
It is well established that arbuscular mycorrhizal (AM) fungi can play a significant role in sustainable crop production and environmental conservation. With the increasing awareness of the ecological significance of mycorrhizas and their diversity, research needs to be directed away from simple records of their occurrence or casual speculation of their function (Smith and Read 1997). Rather, the need is for empirical studies and investigations of the quantitative aspects of the distribution of different types and their contribution to the function of ecosystems.
There is no such thing as a fungal effect or a plant effect, but there is an interaction between both symbionts. This results from the AM fungi and plant community size and structure, soil and climatic conditions, and the interplay between all these factors (Kahiluoto et al. 2000). Consequently, it is readily understood that it is the problems associated with methodology that limit our understanding of the functioning and effects of AM fungi within field communities.
Given the ubiquous presence of AM fungi, a major constraint to the evaluation of the activity of AM colonisation has been the need to account for the indigenous soil native inoculum. This has to be controlled (i.e. reduced or eliminated) if we are to obtain a true control treatment for analysis of arbuscular mycorrhizas in natural substrates. There are various procedures possible for achieving such an objective, and the purpose of this chapter is to provide details of a number of techniques and present some evaluation of their advantages and disadvantages.
Although there have been a large number of experiments to investigated the effectiveness of different sterilization procedures for reducing pathogenic soil fungi, little information is available on their impact on beneficial organisms such as AM fungi. Furthermore, some of the techniques have been shown to affect physical and chemical soil characteristics as well as eliminate soil microorganisms that can interfere with the development of mycorrhizas, and this creates difficulties in the interpretation of results simply in terms of possible mycorrhizal activity.
An important subject is the differentiation of methods that involve sterilization from those focussed on indigenous inoculum reduction. Soil sterilization aims to destroy or eliminate microbial cells while maintaining the existing chemical and physical characteristics of the soil (Wolf and Skipper 1994). Consequently, it is often used for experiments focussed on specific AM fungi, or to establish a negative control in some other types of study. In contrast, the purpose of inoculum reduction techniques is to create a perturbation that will interfere with mycorrhizal formation, although not necessarily eliminating any component group within the inoculum. Such an approach allows the establishment of different degrees of mycorrhizal formation between treatments and the study of relative effects.
Frequently the basic techniques used to achieve complete sterilization or just an inoculum reduction may be similar but the desired outcome is accomplished by adjustments of the dosage or intensity of the treatment. The ultimate choice of methodology for establishing an adequate non-mycorrhizal control depends on the design of the particular experiments, the facilities available and the amount of soil requiring treatment
Control of magnetic anisotropy by orbital hybridization in (La0.67Sr0.33MnO3)n/(SrTiO3)n superlattice
The asymmetry of chemical nature at the hetero-structural interface offers an
unique opportunity to design desirable electronic structure by controlling
charge transfer and orbital hybridization across the interface. However, the
control of hetero-interface remains a daunting task. Here, we report the
modulation of interfacial coupling of (La0.67Sr0.33MnO3)n/(SrTiO3)n
superlattices by manipulating the periodic thickness with n unit cells of
SrTiO3 and n unit cells La0.67Sr0.33MnO3. The easy axis of magnetic anisotropy
rotates from in-plane (n = 10) to out-of-plane (n = 2) orientation at 150 K.
Transmission electron microscopy reveals enlarged tetragonal ratio > 1 with
breaking of volume conservation around the (La0.67Sr0.33MnO3)n/(SrTiO3)n
interface, and electronic charge transfer from Mn to Ti 3d orbitals across the
interface. Orbital hybridization accompanying the charge transfer results in
preferred occupancy of 3d3z2-r2 orbital at the interface, which induces a
stronger electronic hopping integral along the out-of-plane direction and
corresponding out-of-plane magnetic easy axis for n = 2. We demonstrate that
interfacial orbital hybridization in superlattices of strongly correlated
oxides may be a promising approach to tailor electronic and magnetic properties
in device applications
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