168 research outputs found
Coulomb Gap: How a Metal Film Becomes an Insulator
Electron tunneling measurements of the density of states (DOS) in ultra-thin
Be films reveal that a correlation gap mediates their insulating behavior. In
films with sheet resistance the correlation singularity appears
as the usual perturbative zero bias anomaly (ZBA) in the DOS. As R is
increased further, however, the ZBA grows and begins to dominate the DOS
spectrum. This evolution continues until a non-perturbative
Efros-Shklovskii Coulomb gap spectrum finally emerges in the highest R films.
Transport measurements of films which display this gap are well described by a
universal variable range hopping law .Comment: 4 figure
Development of Modern Trends in Higher and Secondary Professional School Based on Innovative Development
The article considers innovative processes taking place in modern socio-economic conditions in the system of higher and secondary professional education in the Russian Federation. The study points out negative factors that prevent the formation of innovative processes in the economy. They identify innovative ways of development in the system of higher and secondary professional schools and essential differences in the definition of significant trends of development. The study has defined a socially-oriented model as the most progressive model of innovative development of higher education institutions. It is the social-oriented model that allows us integrating scientific-research and professional-oriented assets creating an innovative environment in higher education. Other processes are typical for secondary vocational education, the main purpose of which is defined as providing the middle level of the Russian economy with highly skilled workers and specialists. The study has revealed that there are approach processes of the secondary vocational education system with production. Business structures are taking more active part in the organization of the educational process every year. In recent years, interregional centers of competence and vocational training centers have been created on the basis of professional educational organizations mean by innovative frameworks
Keywords: innovation, higher education, secondary vocational education, educational institution
Low temperature field-effect in crystalline organic material
Molecular organic materials offer the promise of novel electronic devices but
also present challenges for understanding charge transport in narrow band
systems. Low temperature studies elucidate fundamental transport processes. We
report the lowest temperature field effect transport results on a crystalline
oligomeric organic material, rubrene. We find field effect switching with
on-off ratio up to 10^7 at temperatures down to 10 K. Gated transport shows a
factor of ~10 suppression of the thermal activation energy in 10-50 K range and
nearly temperature independent resistivity below 10 K.Comment: 5 pages, 4 figure
Residual nuclide formation in 206,207,208,nat-Pb and 209-Bi induced by 0.04-2.6 GeV Protons as well as in 56-Fe induced by 0.3-2.6 GeV Protons
5972 independent and cumulative yields of radioactive residuals nuclei have
been measured in 55 thin 206,207,208,nat-Pb and 209-Bi targets irradiated by
0.04, 0.07, 0.10, 0.15, 0.25, 0.6, 0.8, 1.2, 1.4, 1.6, and 2.6 GeV protons.
Besides, 219 yields have been measured in 0.3, 0.5, 0.75, 1.0, 1.5, and 2.6 GeV
proton-irradiated 56-Fe target. The protons were extracted from the ITEP U-10
synchrotron. The measured data are compared with experimental results obtained
elsewhere and with theoretical calculations by LAHET, MCNPX, CEM03, LAQGSM03,
CASCADE, CASCADO, and LAHETO codes. The predictive power was found to be
different for each of the codes tested, but was satisfactory on the whole in
the case of spallation products. At the same time, none of the codes can
de-scribe well the product yields throughout the whole product mass range, and
all codes must be further improved.Comment: 4 pages, 4 figures, 2 tables, only pdf file, to be published in Proc.
Int. Conf. on Nucl. Data for Sci. and Technology (ND2007), Nice, France,
April 22-27, 20
Tenfold Magnetoconductance in a Non-Magnetic Metal Film
We present magnetoconductance (MC) measurements of homogeneously disordered
Be films whose zero field sheet conductance (G) is described by the
Efros-Shklovskii hopping law . The low field
MC of the films is negative with G decreasing 200% below 1 T. In contrast the
MC above 1 T is strongly positive. At 8 T, G increases 1000% in perpendicular
field and 500% in parallel field. In the simpler parallel case, we observe {\em
field enhanced} variable range hopping characterized by an attenuation of
via the Zeeman interaction.Comment: 9 pages including 5 figure
High-energy threshold reaction rates on 0.8 GeV proton-irradiated thick Pb-target
This works presents results of activation-aided determination of threshold
reaction rates in 92 209Bi, natPb, 197Au, 181Ta, 169Tm, natIn, 93Nb, 64Zn,
65Cu, 63Cu, 59Co, 19F, and 12C samples and in 121 27Al samples. All the samples
were aligned with the proton beam axis inside and outside the demountable 92-cm
thick Pb target of 15-cm diameter assembled of 23 4-cm thick discs. The samples
were placed on 12 target disks to reproduce the long axis distribution of
protons and neutrons. In June 2006, the target was exposed for 18 hours to a
800-MeV proton beam extracted from the ITEP U-10 accelerator. The proton
fluence and the proton beam shape were determined using the 27Al(p,x)7Be
monitor reaction. The reaction rates were determined by the direct
gamma-spectrometry techniques. In total, 1196 gamma-spectra have been measured,
and about 1500 reaction rates determined. The measured reaction rates were
simulated by the MCNPX code using the following databases: ENDF/B6 for neutrons
below 20 MeV, MENDL2 for 20-100 MeV neutrons, and MENDL2P for proton cross
sections up to 200 MeV. An acceptable agreement of simulations with
experimental data has been found.Comment: 4 pages, 5 figures, 3 tables, only pdf file, to be published in Proc.
Int. Conf. on Nucl. Data for Sci. and Technology (ND2007), Nice, France,
April 22-27, 200
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