Nonexponential Relaxations in a Two-Dimensional Electron System in Silicon

The relaxations of conductivity have been studied in a strongly disordered two-dimensional (2D) electron system in Si after excitation far from equilibrium by a rapid change of carrier density n_s at low temperatures T. The dramatic and precise dependence of the relaxations on n_s and T strongly suggests (a) the transition to a glassy phase as T->0, and (b) the Coulomb interactions between 2D electrons play a dominant role in the observed out-of-equilibrium dynamics.Comment: 5 pages, 5 figure

The glass transition and the Coulomb gap in electron glasses

We establish the connection between the presence of a glass phase and the appearance of a Coulomb gap in disordered materials with strongly interacting electrons. Treating multiparticle correlations in a systematic way, we show that in the case of strong disorder a continuous glass transition takes place whose Landau expansion is identical to that of the Sherrington-Kirkpatrick spin glass. We show that the marginal stability of the glass phase controls the physics of these systems: it results in slow dynamics and leads to the formation of a Coulomb gap

The sources of the deep water of the Eastern Mediterranean Sea

The deep water in the two basins of the eastern Mediterranean Sea, the Levant and the Ionian Sea, is identical in temperature and salinity though differing slightly in oxygen content. Contrary to Nielsen\u27s thesis, none of this water is formed in the southern Aegean Sea...

Static stability parameters in oceanography

The use of static vertical stability criteria in oceanography is discussed and two basic types of such stability parameters are derived. It is shown how these can be determined by using sound velocity as one of the variables. Computation can be simplified by means of a graph

Notes on determining the depths of sampling in serial oceanographic observations

In order to interpolate between thermometrically determined depths of sampling in serial oceanographic observations it ha.s been customary to plot a curve of depth to wire length ratio against wire length. It is shown that a simpler and probably more accurate method consists of plotting wire length minus depth against wire length. In this method the surface wire angle is converted into a line of tangency to the curve which always terminates at the zero point of the graph. Furthermore, the limiting slope of this curve is more readily defined and utilized

The use of electrical conductivity measurements for chlorinity determination

Limitations in our knowledge of the electrical conductivity of sea water are discussed. An empirical equation is presented which gives chlorinity aa a function of specific conductance and temperature at atmospheric pressure

Electroreflectance spectroscopy in self-assembled quantum dots: lens symmetry

Modulated electroreflectance spectroscopy $\Delta R/R$ of semiconductor self-assembled quantum dots is investigated. The structure is modeled as dots with lens shape geometry and circular cross section. A microscopic description of the electroreflectance spectrum and optical response in terms of an external electric field (${\bf F}$) and lens geometry have been considered. The field and lens symmetry dependence of all experimental parameters involved in the $\Delta R/R$ spectrum have been considered. Using the effective mass formalism the energies and the electronic states as a function of ${\bf F}$ and dot parameters are calculated. Also, in the framework of the strongly confined regime general expressions for the excitonic binding energies are reported. Optical selection rules are derived in the cases of the light wave vector perpendicular and parallel to $$. Detailed calculation of the Seraphin coefficients and electroreflectance spectrum are performed for the InAs and CdSe nanostructures. Calculations show good agreement with measurements recently performed on CdSe/ZnSe when statistical distribution on size is considered, explaining the main observed characteristic in the electroreflectance spectra

Dielectric susceptibility of the Coulomb-glass

We derive a microscopic expression for the dielectric susceptibility $\chi$ of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation-dissipation theorem tells us that $\chi$ is a function of the thermal fluctuations of the dipole moment of the system. We calculate $\chi$ numerically for three-dimensional Coulomb glasses as a function of temperature and frequency

Proposal of a new solution for mold temperature monitoring

The paper deals with the proposal of a new solution for monitoring the mold temperature. The mold is used for the production of thermosetting products by pressing technology. At present, the mold temperature is measured separately at sixteen locations of the mold. This measurement is lengthy and laborious, causing production downtime. At the same time, measurement is physically problematic since the mold has a temperature in the range of 130 to 150°C. The controller must manually record all measured data in the record and re-write the record to the computer. The new solution is to measure four control points at once. The controller will measure these points and the measured data will be sent online to the system. This method will clearly speed up the measurement process

Sigma-t surfaces in the Atlantic Ocean

Wüst (1936) shows the distribution