581 research outputs found
Comparison of thread-cutting behaviour in three specialist predatory mites to cope with complex webs of Tetranychus spider mites
Anti-predator defenses provided by complex webs of Tetranychus mites can severely impede the performance of generalist predatory mites, whereas this may not be true for specialist predatory mites. Although some specialist predatory mites have developed morphological protection to reduce the adverse effects of complex webs, little is known about their behavioral abilities to cope with the webs. In this study, we compared thread-cutting behavior of three specialist predatory mites, Phytoseiulus persimilis, Neoseiulus womersleyi and N. californicus, exhibited inside the complex web of T. urticae. No major difference was observed among them in the basic pattern of this behavior, using chelicerae and palps, and in the number of silken threads severed while moving inside the web. These results and observations suggest that each predator species cut many sticky silken threads to move inside the complex web without suffering from serious obstructio
Development of a beamline for the study of interactions between a relativistic electron beam and crystals at the SAGA Light Source
A beamline dedicated to the study of interactions of a relativistic electron beam with crystals has been designed and constructed at the SAGA Light Source (SAGA-LS). This beamline consists of a compact two-axis goniometer in a
vacuum chamber and two screen monitors placed downstream of the goniometer. An electron beam is provided from the SAGA-LS injector linac. The beam parameters such as the beam emittance and the Twiss parameters have been measured
using the “Q-scan method”. Proposals for experiments on channeling radiation and parametric X-ray radiation are also discussed
Spin frustration and magnetic ordering in theS=12molecular antiferromagnetfcc−Cs3C60
We have investigated the low-temperature magnetic state of face-centered-cubic (fcc) Cs3C60, a Mott insulator and the first molecular analog of a geometrically frustrated Heisenberg fcc antiferromagnet with S=1/2 spins. Specific heat studies reveal the presence of both long-range antiferromagnetic ordering and a magnetically disordered state below TN=2.2 K, which is in agreement with local probe experiments. These results together with the strongly suppressed TN are unexpected for conventional atom-based fcc antiferromagnets, implying that the fulleride molecular degrees of freedom give rise to the unique magnetic ground state
Experimental Study of Proton Irradiation on C3H/He Mice
開始ページ、終了ページ: 冊子体のページ付
Hadron and Quark Form Factors in the Relativistic Harmonic Oscillator Model
Nucleon, pion and quark form factors are studied within the relativistic
harmonic oscillator model including the quark spin. It is shown that the
nucleon charge, magnetic and axial form factors and the pion charge form factor
can be explained with one oscillator parameter if one accounts for the scaling
rule and the size of the constituent quarks.Comment: 9 pages, Latex, 3 postscript figures, DFTT 8/9
Planar channelling of relativistic electrons in half-wave silicon crystal and corresponding radiation
New experimental data on planar channeling of 255 MeV electrons in a 0.74 µm Si Half-Wave Crystal (HWC) obtained at SAGA-LS facility are presented. The computer simulation showed that the angular distribution of electrons after penetration through the HWC revealed the number of unknown before peculiarities is connected with specific electron trajectories in HWC. These specific trajectories lead to specific radiation, the properties of which are analyzed
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
Crystal structure of the new FeSe1-x superconductor
The newly discovered superconductor FeSe1-x (x=0.08, Tconset=13.5 K at
ambient pressure rising to 27 K at 1.48 GPa) exhibits a structural phase
transition from tetragonal to orthorhombic below 70 K at ambient pressure - the
crystal structure in the superconducting state shows remarkable similarities to
that of the REFeAsO1-xFx (RE = rare earth) superconductorsComment: Chem. Commun. (2008
Magnetism and Charge Dynamics in Iron Pnictides
In a wide variety of materials, such as copper oxides, heavy fermions,
organic salts, and the recently discovered iron pnictides, superconductivity is
found in close proximity to a magnetically ordered state. The character of the
proximate magnetic phase is thus believed to be crucial for understanding the
differences between the various families of unconventional superconductors and
the mechanism of superconductivity. Unlike the AFM order in cuprates, the
nature of the magnetism and of the underlying electronic state in the iron
pnictide superconductors is not well understood. Neither density functional
theory nor models based on atomic physics and superexchange, account for the
small size of the magnetic moment. Many low energy probes such as transport,
STM and ARPES measured strong anisotropy of the electronic states akin to the
nematic order in a liquid crystal, but there is no consensus on its physical
origin, and a three dimensional picture of electronic states and its relations
to the optical conductivity in the magnetic state is lacking. Using a first
principles approach, we obtained the experimentally observed magnetic moment,
optical conductivity, and the anisotropy of the electronic states. The theory
connects ARPES, which measures one particle electronic states, optical
spectroscopy, probing the particle hole excitations of the solid and neutron
scattering which measures the magnetic moment. We predict a manifestation of
the anisotropy in the optical conductivity, and we show that the magnetic phase
arises from the paramagnetic phase by a large gain of the Hund's rule coupling
energy and a smaller loss of kinetic energy, indicating that iron pnictides
represent a new class of compounds where the nature of magnetism is
intermediate between the spin density wave of almost independent particles, and
the antiferromagnetic state of local moments.Comment: 4+ pages with additional one-page supplementary materia
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