274 research outputs found
Evidence of Nodal Line in the Superconducting Gap Symmetry of Noncentrosymmetric ThCoC
The newly discovered noncentrosymmetric superconductor ThCoC exhibits
numerous unconventional behavior in the field dependent heat capacity data.
Here we present the first measurement of the gap symmetry of ThCoC by
muon spin rotation/relaxation SR) measurements. Temperature dependence of
the magnetic penetration depth measured using the transverse field SR
measurement reveal the evidence of nodal pairing symmetry. To understand these
findings, we carry out the calculations of superconducting pairing eigenvalue
and eigenfunction symmetry due to the spin-fluctuation mechanism, by directly
implemented the {\it ab-initio} band structures. We find that the system
possesses a single Fermi surface with considerable three-dimensionality, and
hence a strong nesting along the -direction. Such a nesting promotes a
superconducting pairing with a -like symmetry with a prominent nodal
line on the plane. The result agrees well with the experimental
data.Comment: 3 pages, 5 figure
Physical properties of noncentrosymmetric superconductor LaIrSi3: A {\mu}SR study
The results of heat capacity C_p(T, H) and electrical resistivity \rho(T,H)
measurements down to 0.35 K as well as muon spin relaxation and rotation
(\muSR) measurements on a noncentrosymmetric superconductor LaIrSi3 are
presented. Powder neutron diffraction confirmed the reported noncentrosymmetric
body-centered tetragonal BaNiSn3-type structure (space group I4\,mm) of
LaIrSi3. The bulk superconductivity is observed below T_c = 0.72(1) K. The
intrinsic \Delta C_e/\gamma_n T_c = 1.09(3) is significantly smaller than the
BCS value of 1.43, and this reduction is accounted by the \alpha-model of BCS
superconductivity. The analysis of the superconducting state C_e(T) data by the
single-band \alpha-model indicates a moderately anisotropic order parameter
with the s-wave gap \Delta(0)/k_B T_c = 1.54(2) which is lower than the BCS
value of 1.764. Our estimates of various normal and superconducting state
parameters indicate a weakly coupled electron-phonon driven type-I s-wave
superconductivity in LaIrSi3. The \muSR results also confirm the conventional
type-I superconductivity in LaIrSi3 with a preserved time reversal symmetry and
hence a singlet pairing superconducting ground state.Comment: 11 pages, 8 figures, 2 table
Light-ion production in the interaction of 175 MeV quasi-mono-energetic neutrons with iron and with bismuth
Nuclear data for neutron-induced reactions in the intermediate energy range
of 20 to 200 MeV are of great importance for the development of nuclear
reaction codes since little data exist in that range. Also several different
applications benefit from such data, notably accelerator-driven incineration of
nuclear waste. The Medley setup was used for a series of measurements of p, d,
t, He and -particle production by 175 MeV quasi-mono-energetic
neutrons on various target nuclei. The measurements were performed at the The
Svedberg Laboratory in Uppsala, Sweden. Eight detector telescopes placed at
angles between 20 and 160 were used. Medley uses the -- technique to discriminate among the particle types and is
able to measure double-differential cross sections over a wide range of
particle energies. This paper briefly describes the experimental setup,
summarizes the data analysis and reports on recent changes in the previously
reported preliminary data set on bismuth. Experimental data are compared with
INCL4.5-Abla07, MCNP6 using CEM03.03, TALYS and PHITS model calculations as
well as with nuclear data evaluations. The models agree fairly well overall but
in some cases systematic differences are found.Comment: 16 pages, 19 figures; submitted to Phys. Rev.
Recent advances of metabolomics in plant biotechnology
Biotechnology, including genetic modification, is a very important approach to regulate the production of particular metabolites in plants to improve their adaptation to environmental stress, to improve food quality, and to increase crop yield. Unfortunately, these approaches do not necessarily lead to the expected results due to the highly complex mechanisms underlying metabolic regulation in plants. In this context, metabolomics plays a key role in plant molecular biotechnology, where plant cells are modified by the expression of engineered genes, because we can obtain information on the metabolic status of cells via a snapshot of their metabolome. Although metabolome analysis could be used to evaluate the effect of foreign genes and understand the metabolic state of cells, there is no single analytical method for metabolomics because of the wide range of chemicals synthesized in plants. Here, we describe the basic analytical advancements in plant metabolomics and bioinformatics and the application of metabolomics to the biological study of plants
In-medium nuclear interactions of low-energy hadrons
Experimental and theoretical developments of the last decade in the study of
exotic atoms and some related low-energy reactions are reviewed, in order to
provide information on the in-medium hadron-nucleon t matrix over a wide range
of densities up to central nuclear densities. In particular, we review pionic
deeply bound atomic states and related evidence for partial restoration of
chiral symmetry in dense nuclear matter. The case for relatively narrow deeply
bound atomic states for antikaons and antiprotons is made, based on the physics
of strong nuclear absorption. Recent experimental suggestions for signals of
antikaon-nuclear deeply bound states are reviewed, and dynamical models for
calculating binding energies, widths and densities of antikaon nuclear states
are discussed. Specific features of low-energy in-medium interactions of kaons,
antiprotons and of Sigma hyperons are discussed, and suggestions to study
experimentally Cascade atoms are reviewed.Comment: 86 pages, 44 figures, slight revisions, references added, Physics
Reports (in press
Identification of distinct human invariant natural killer T-cell response phenotypes to alpha-galactosylceramide.
Background
Human CD1d-restricted, invariant natural killer T cells (iNKT) are a unique class of T lymphocytes that recognise glycolipid antigens such as α-galactosylceramide (αGalCer) and upon T cell receptor (TCR) activation produce both Th1 and Th2 cytokines. iNKT cells expand when cultured in-vitro with αGalCer and interleukin 2 (IL-2) in a CD1d-restricted manner. However, the expansion ratio of human iNKT cells varies between individuals and this has implications for attempts to manipulate this pathway therapeutically. We have studied a panel of twenty five healthy human donors to assess the variability in their in-vitro iNKT cell expansion responses to stimulation with CD1d ligands and investigated some of the factors that may influence this phenomenon.
Results
Although all donors had comparable numbers of circulating iNKT cells their growth rates in-vitro over 14 days in response to a range of CD1d ligands and IL-2 were highly donor-dependent. Two reproducible donor response patterns of iNKT expansion were seen which we have called 'strong' or 'poor' iNKT responders. Donor response phenotype did not correlate with age, gender, frequency of circulating iNKT, or with the CD1d ligand utilised. Addition of exogenous recombinant human interleukin 4 (IL-4) to 'poor' responder donor cultures significantly increased their iNKT proliferative capacity, but not to levels equivalent to that of 'strong' responder donors. However in 'strong' responder donors, addition of IL-4 to their cultures did not significantly alter the frequency of iNKT cells in the expanded CD3+ population.
Conclusion
(i) in-vitro expansion of human iNKT cells in response to CD1d ligand activation is highly donor variable, (ii) two reproducible patterns of donor iNKT expansion were observed, which could be classified into 'strong' and 'poor' responder phenotypes, (iii) donor iNKT response phenotypes did not correlate with age, gender, frequency of circulating iNKT cells, or with the CD1d ligand utilised, (iv) addition of IL-4 to 'poor' but not 'strong' responder donor cultures significantly increased their in-vitro iNKT cell expansion to αGalCer
The effect of spin orbit interaction on the physical properties of LaTSi3 (T = Ir, Pd, and Rh): First-principles calculations
This is the final version of the article. Available from AIP Publishing via the DOI in this record.We have presented the structural, elastic, electronic, phononic, and electron-phonon interaction properties of the La-based noncentrosymmetric superconductors, such as LaIrSi3, LaRhSi3, and LaPdSi3, by using the generalized gradient approximation of the density functional theory. The calculated elastic constants reveal the mechanical stability of all the studied compounds in their noncentrosymmetric structure, while the lack of inversion symmetry gives rise to lift the degeneracy of their electronic bands, except in the Γ-Z and X-P directions. The calculated Eliashberg spectral function shows that all phonon branches of these materials couple considerably with electrons, and thus, all of them make contribution to the average electron-phonon coupling parameter λ. Using the calculated values of λ and the logarithmically averaged phonon frequency ωln, the superconducting critical temperature Tc values for LaIrSi3, LaRhSi3, and LaPdSi3 are estimated to be 0.89, 2.56, and 2.40 K, respectively, which accord very well with their corresponding experimental values of 0.77, 2.16, and 2.60 K.This work was supported by the Scientific and Technical Research Council of Turkey (TÜBİTAK) (Project No. MFAG-115F135)
Discovery of naked charm particles and lifetime differences among charm species using nuclear emulsion techniques innovated in Japan
This is a historical review of the discovery of naked charm particles and lifetime differences among charm species. These discoveries in the field of cosmic-ray physics were made by the innovation of nuclear emulsion techniques in Japan. A pair of naked charm particles was discovered in 1971 in a cosmic-ray interaction, three years prior to the discovery of the hidden charm particle, J/Ψ, in western countries. Lifetime differences between charged and neutral charm particles were pointed out in 1975, which were later re-confirmed by the collaborative Experiment E531 at Fermilab. Japanese physicists led by K.Niu made essential contributions to it with improved emulsion techniques, complemented by electronic detectors. This review also discusses the discovery of artificially produced naked charm particles by us in an accelerator experiment at Fermilab in 1975 and of multiple-pair productions of charm particles in a single interaction in 1987 by the collaborative Experiment WA75 at CERN
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