11,967 research outputs found
Differential Input from the Amygdaloid Body to the Ventromedial Hypothalamic Nucleus in the Rat
Differential amygdaloid afferents to anterior dorsal, anterior ventral, posterior dorsal and posterior ventral subdivisions of the ventromedial hypothalamic nucleus (VMH) were studied by means of retrograde transport of horseradish peroxidase (HRP). Injections of tracer confined to the VMH subdivisions mentioned, and enhancement of tracer uptake and transport were achieved by iontophoretic delivery of an HRP solution containing poly-L-α-ornithine. It was shown that the medial, central, basolateral, basomedial, lateroposterior and intercalated nuclei of the amygdala constitute afferent input sources to the ventromedial nucleus in a topographic pattern related to the various subdivisions of the VMH. This topographically organized amygdala-VMH projection is discussed against the background of the functional role that both amygdala and VMH play in the control of feeding, apart from various other autonomous functions that both brain centers are known to be concerned with.
Experiment of static and dynamic characteristics of spiral grooved seals
The leakages and the dynamic characteristics of six types of spiral grooved seals are experimentally investigated. The effect of the helix angle of the seal is investigated mainly under the condition of the same nominal clearances, land and groove lengths, and groove depths. The dynamic characteristics are measured for various parameters such as preswirl velocity, pressure difference between inlet and outlet of the seal, whirling amplitude, whirling speed, and rotating speed of the rotor. The results are also compared with leakage increases with the increase of the helix angle, but as the rotating speed increases, the leakages of the larger helix angle seals quickly drop. The leakage of the smooth-stator (SS)/smooth-grooved rotor (SGR) seal drops faster than that of the spiral-grooved stator (SGS)/smooth-rotor (SR) seal. It is found that a circumferential flow can be produced by the flow along the helix angle direction, and this circumferential flow acts as a negative swirl. For the present helix angle range, there is an optimum helix angle with which the seal has a comparatively positive effect on the rotor stability. Compared with the SGS/SR seals, the SS/SGR seal has a worse effect on the rotor stability
Single-dot spectroscopy via elastic single-electron tunneling through a pair of coupled quantum dots
We study the electronic structure of a single self-assembled InAs quantum dot
by probing elastic single-electron tunneling through a single pair of weakly
coupled dots. In the region below pinch-off voltage, the non-linear threshold
voltage behavior provides electronic addition energies exactly as the linear,
Coulomb blockade oscillation does. By analyzing it, we identify the s and p
shell addition spectrum for up to six electrons in the single InAs dot, i.e.
one of the coupled dots. The evolution of shell addition spectrum with magnetic
field provides Fock-Darwin spectra of s and p shell.Comment: 7 pages, 3 figures, Accepted for publication in Phys. Rev. Let
Electrochemical synthesis and properties of CoO2, the x = 0 phase of the AxCoO2 systems (A = Li, Na)
Single-phase bulk samples of the "exotic" CoO2, the x = 0 phase of the AxCoO2
systems (A = Li, Na), were successfully synthesized through electrochemical
de-intercalation of Li from pristine LiCoO2 samples. The samples of pure CoO2
were found to be essentially oxygen stoichiometric and possess a hexagonal
structure consisting of stacked triangular-lattice CoO2 layers only. The
magnetism of CoO2 is featured with a temperature-independent susceptibility of
the magnitude of 10-3 emu/mol Oe, being essentially identical to that of a
Li-doped phase, Li0.12CoO2. It is most likely that the CoO2 phase is a
Pauli-paramagnetic metal with itinerant electrons.Comment: 12 pages, 3 figure
Dynamic nuclear polarization induced by breakdown of fractional quantum Hall effect
We study dynamic nuclear polarization (DNP) induced by breakdown of the
fractional quantum Hall (FQH) effect. We find that voltage-current
characteristics depend on current sweep rates at the quantum Hall states of
Landau level filling factors = 1, 2/3, and 1/3. The sweep rate dependence
is attributed to DNP occurring in the breakdown regime of FQH states. Results
of a pump and probe experiment show that the polarities of the DNP induced in
the breakdown regimes of the FQH states is opposite to that of the DNP induced
in the breakdown regimes of odd-integer quantum Hall states.Comment: 4 pages, 4 figure
Multi-layer structure of mid-latitude sporadic-<i>E</i> observed during the SEEK-2 campaign
In the mid-latitude ionospheric region, sporadic-<i>E</i> layers (<i>E<sub>s</sub></i> layers) have often been observed, revealing multiple layers. The <i>E<sub>s</sub></i> layers observed during the SEEK-2 rocket campaign showed double electron density peaks; namely, there are stable lower peaks and relatively unstable upper peaks. We examined the effects of wind shear and the electric fields on the generation of the multiple layer structure, in comparison with the electron density profile, the neutral wind, and the DC electric field observed by the S310 rocket experiments. The results showed that the neutral wind shear is mainly responsible for the generation of the lower layer, while the DC electric field makes a significant contribution to the formation of the upper layer. The difference between the lower and upper layers was also explained by the enhanced AC electric field observed at about 103–105 km altitude. The external DC electric field intensity is expected to be ~5 mV/m, which is enough to contribute to generate the <i>E<sub>s</sub></i> layers in the ionosphere.<br><br> <b>Keywords.</b> Ionosphere (Electric fields; Ionospheric irregularities, Mid-latitude ionosphere
Fabrication of graphene nanoribbon by local anodic oxidation lithography using atomic force microscope
We conducted local anodic oxidation (LAO) lithography in single-layer,
bilayer, and multilayer graphene using tapping-mode atomic force microscope.
The width of insulating oxidized area depends systematically on the number of
graphene layers. An 800-nm-wide bar-shaped device fabricated in single-layer
graphene exhibits the half-integer quantum Hall effect. We also fabricated a
55-nm-wide graphene nanoribbon (GNR). The conductance of the GNR at the charge
neutrality point was suppressed at low temperature, which suggests the opening
of an energy gap due to lateral confinement of charge carriers. These results
show that LAO lithography is an effective technique for the fabrication of
graphene nanodevices.Comment: 4 pages, 4 figure
Oblique triangular antiferromagnetic phase in CsCuCoCl
The spin-1/2 stacked triangular antiferromagnet CsCuCoCl with
undergoes two phase transitions at zero field. The
low-temperature phase is produced by the small amount of Co doping. In
order to investigate the magnetic structures of the two ordered phases, the
neutron elastic scattering experiments have been carried out for the sample
with . It is found that the intermediate phase is identical to
the ordered phase of CsCuCl, and that the low-temperature phase is an
oblique triangular antiferromagnetic phase in which the spins form a triangular
structure in a plane tilted from the basal plane. The tilting angle which is
42 at K decreases with increasing temperature, and becomes
zero at K. An off-diagonal exchange term is proposed as the
origin of the oblique phase.Comment: 6 pages, 7 figure
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