777 research outputs found
The diagnostic significance of the Stimulation of TSH secretion by administration of thyrotropin releasing hormone ( TRH ) in diseases of the hypothalamus and pituitary
On Retardation Effects in Space Charge Calculations Of High Current Electron Beams
Laser-plasma accelerators are expected to deliver electron bunches with high
space charge fields. Several recent publications have addressed the impact of
space charge effects on such bunches after the extraction into vacuum.
Artifacts due to the approximation of retardation effects are addressed, which
are typically either neglected or approximated. We discuss a much more
appropriate calculation for the case of laser wakefield acceleration with
negligible retardation artifacts due to the calculation performed in the mean
rest frame. This presented calculation approach also aims at a validation of
other simulation approaches
Magnetic field-induced one-magnon Raman scattering in the magnon Bose-Einstein condensation phase of TlCuCl
We report the observation of the -symmetric one-magnon Raman peak
in the magnon Bose-Einstein condensation phase of TlCuCl. Its Raman shift
traces the one-magnon energy at the magnetic point, and its intensity
is proportional to the squared transverse magnetization. The appearance of the
one-magnon Raman scattering originates from the exchange magnon Raman process
and reflects the change of the magnetic-state symmetry. Using the bond-operator
representation, we theoretically clarify the Raman selection rules, being
consistent with the experimental results.Comment: 6 pages, 4 figure
Spin gap and Luttinger liquid description of the NMR relaxation in carbon nanotubes
Recent NMR experiments by Singer et al. [Singer et al. Phys. Rev. Lett. 95,
236403 (2005).] showed a deviation from Fermi-liquid behavior in carbon
nanotubes with an energy gap evident at low temperatures. Here, a comprehensive
theory for the magnetic field and temperature dependent NMR 13C spin-lattice
relaxation is given in the framework of the Tomonaga-Luttinger liquid. The low
temperature properties are governed by a gapped relaxation due to a spin gap (~
30K), which crosses over smoothly to the Luttinger liquid behaviour with
increasing temperature.Comment: 5 pages, 1 figure, 1 tabl
All-optical phase-regenerative multicasting of 40 Gbit/s DPSK signal in a degenerate phase sensitive amplifier
We demonstrate all-optical 1-to-5 differential phase-shift keyed (DPSK) wavelength multicasting at 40 Gbit/s using a degenerate four-wave mixing (FWM) based phase sensitive amplifier (PSA). Phase regenerative properties are reported with a sensitivity improvement of more that 10 dB
Saturation effects in degenerate phase sensitive fiber optic parametric amplifiers
We experimentally study saturation effects in degenerate phase sensitive amplifiers, revealing and explaining a gain regime suitable for all-optical signal processing functions such as phase regeneration
Observation of correlations up to the micrometer scale in sliding charge-density waves
High-resolution coherent x-ray diffraction experiment has been performed on
the charge density wave (CDW) system KMoO. The satellite
reflection associated with the CDW has been measured with respect to external
dc currents. In the sliding regime, the satellite reflection displays
secondary satellites along the chain axis which corresponds to correlations up
to the micrometer scale. This super long range order is 1500 times larger than
the CDW period itself. This new type of electronic correlation seems inherent
to the collective dynamics of electrons in charge density wave systems. Several
scenarios are discussed.Comment: 4 pages, 3 figures Typos added, references remove
Dynamic Compressibility and aging in Wigner crystals and quantum glasses
We study the non-equilibrium linear response of quantum elastic systems
pinned by quenched disorder with Schwinger-Keldysh real-time techniques
complemented by a mean-field variational approach. We find (i) a
quasi-equilibrium regime in which the analytic continuation from the
imaginary-time replica results holds provided the marginality condition is
enforced; (ii) an aging regime. The conductivity and compressibility are
computed. The latter is found to cross over from its dynamic to static value on
a scale set by the waiting time after a quench, an effect which can be probed
in experiments in {\it e.g.} Wigner glasses
Temperature dependence of the excitation spectrum in the charge-density-wave ErTe and HoTe systems
We provide optical reflectivity data collected over a broad spectral range
and as a function of temperature on the ErTe and HoTe materials, which
undergo two consecutive charge-density-wave (CDW) phase transitions at
= 265 and 288 K and at = 157 and 110 K, respectively. We
observe the temperature dependence of both the Drude component, due to the
itinerant charge carriers, and the single-particle peak, ascribed to the
charge-density-wave gap excitation. The CDW gap progressively opens while the
metallic component gets narrow with decreasing temperature. An important
fraction of the whole Fermi surface seems to be affected by the CDW phase
transitions. It turns out that the temperature and the previously investigated
pressure dependence of the most relevant CDW parameters share several common
features and behaviors. Particularly, the order parameter of the CDW state is
in general agreement with the predictions of the BCS theory
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