8,525 research outputs found
Infinite charge mobility in muscovite at 300K
Evidence is presented for infinite charge mobility in natural crystals of
muscovite mica at room temperature. Muscovite has a basic layered structure
containing a flat monatomic sheet of potassium sandwiched between mirror
silicate layers. It is an excellent electrical insulator. Studies of defects in
muscovite crystals indicated that positive charge could propagate over great
distances along atomic chains in the potassium sheets in absence of an applied
electric potential. The charge moved in association with anharmonic lattice
excitations that moved at about sonic speed and created by nuclear recoil of
the radioactive isotope K40. This was verified by measuring currents passing
through crystals when irradiated with energetic alpha particles at room
temperature. The charge propagated more than 1000 times the range of the alpha
particles of average energy and 250 times the range of channelling particles of
maximum energy. The range is limited only by size of the crystal.Comment: 6 pages, 8 figure
Utilização de Rsync com Windows e Linux para cópias automáticas de segurança introdução O Rsync.
bitstream/CPPSE-2010/18922/1/PROCIComTec89RFS2009.00279.pd
Multiple glomus tumors and segmental neurofibromatosis: there are no coincidences
Segmental neurofibromatosis is a rare subtype of neurofibromatosis type 1 (NF1). Glomus tumors are uncommon benign tumors. The authors report the association between these two rare conditions, not yet reported
Temporal and spatial variations of the absolute reflectivity of Jupiter and Saturn from 0.38 to 1.7 m with PlanetCam-UPV/EHU
We provide measurements of the absolute reflectivity of Jupiter and Saturn
along their central meridians in filters covering a wide range of visible and
near-infrared wavelengths (from 0.38 to 1.7 m) that are not often
presented in the literature. We also give measurements of the geometric albedo
of both planets and discuss the limb-darkening behavior and temporal
variability of their reflectivity values for a period of four years
(2012-2016). This work is based on observations with the PlanetCam-UPV/EHU
instrument at the 1.23 m and 2.2 m telescopes in Calar Alto Observatory
(Spain). The instrument simultaneously observes in two channels: visible (VIS;
0.38-1.0 m) and short-wave infrared (SWIR; 1.0--1.7 m). We obtained
high-resolution observations via the lucky-imaging method. We show that our
calibration is consistent with previous independent determinations of
reflectivity values of these planets and, for future reference, provide new
data extended in the wavelength range and in the time. Our results have an
uncertainty in absolute calibration of 10--20\%. We show that under the
hypothesis of constant geometric albedo, we are able to detect absolute
reflectivity changes related to planetary temporal evolution of about 5-10\%.Comment: 13 pages, 18 figures, (in press
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