| PTN | pain transmission neuron; pleiotrophin; posterior tibial nerve |
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| PTT | partial thromboplastin time; particle transport time; posterior tibial tendon (transfer); prothrombi... |
| RPT | rapid pull-through; refractory period of transmission; Registered Physical Therapist; renal parenchy... |
| t | Greek lower case letter tau; life [of radioisotope]; relaxation time; shear stress; spectral transmi... |
| TCP/IP | transmission control protocol/Internet protocol |
| secondary electron imaging | <microscopy> Production of secondary electrons is very topography related. Due to their low energy, 5eV, only secondaries that are very near the surface (less than 10nm) can exit the sample and be examined. Any changes in topography in the sample that are larger than this sampling depth will change the yield of secondaries due to collection efficiencies. Collection of these electrons is aided by using a collector in conjunction with the secondary electron detector. The collector is a grid or mesh with a +100V potential applied to it which is placed in front of the detector, attracting the negatively charged secondary electrons to it which then pass through the grid-holes and into the detector to be counted. When a Secondary Electrons collide with the solid-state saemiconductor detector an electron-hole pairs are created which are then counted. This quantity is translated into a pixel intensity and displayed on the CRT, forming the image. (05 Aug 1998) |
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| Selected Area Electron Diffraction | <technique> In this diffraction mode an aperture is used to define the area from which a diffraction pattern is to be recorded from a thin sample. This aperture is typically located in an image plane below the sample. Selected Area Electron Diffraction patterns are simple spot patterns and are of use in phase determination (lattice spacing measurement) and defect analysis (sample orientation). Acronym: SAED (05 Aug 1998) |
| internal conversion electron | An electron, similar to an Auger electron, released from one of the electron orbits of the atom upon activation by a gamma-ray from that atom's nucleus; the electron has kinetic energy equal to the net energy transition of the disintegration. (05 Mar 2000) |
| electron | <chemistry, physics> A stable atomic particle that has a negative charge, the flow ofelectrons through a substance constitutes electricity. (19 Jan 1998) |
| electron acceptor | <chemistry> A molecule or compound that gets electrons during an oxidation-reduction reaction. (19 Jan 1998) |
| electron beam | <microscopy> A stream of electrons in an electron optical system. (05 Aug 1998) |
| electron capture | <radiobiology> Nuclear decay process whereby a proton in the nucleus absorbs an orbiting electron and converts to a neutron. (09 Oct 1997) |
| electron carrier | <chemistry> A protein which can either accept or donate electrons in oxidation-reduction reactions. (19 Jan 1998) |
| Electron Channeling Pattern | <microscopy> A pattern formed by the periodic backscattering of electrons by the specimen lattice in a transmission electron microscope. Allows determination of crystal structure and lattice parameters in crystals greater than 10 micrometres diameter. Acronym: ECP (05 Aug 1998) |
| electron cyclotron discharge cleaning | Using relatively low power microwaves (at the electron cyclotron frequency) to create a weakly ionised, essentially unconfined hydrogen plasma in the vacuum chamber. The ions react with impurities on the walls of the tokamak and help remove them from the chamber. For instance, Alcator C-mod typically applies electron cyclotron discharge cleaning for a few days prior to beginning a campaign, and a few hours before each day's run. (09 Oct 1997) |
| electron cyclotron emission | <physics, radiobiology> As electrons gyrate around in a magnetic field (see also larmor radius or cyclotron radius), they radiate radio-frequency electromagnetic waves. This is known as electron cyclotron emission, and can be measured to help diagnose a plasma. (09 Oct 1997) |
| electron cyclotron heating | <physics, radiobiology> Radiofrequency heating scheme that works by injecting electromagnetic wave energy at the electron cyclotron gyration frequency. The electric field of the electromagnetic wave at this frequency looks to a gyrating electron like a static electric field, and thus causes large acceleration of the electron (larger than if the frequency were off the cyclotron frequency and thus, to the electron, appearing to change direction as a function of time). The accelerated electron gains energy, which is then shared with other particles through collisions, resulting in heating. Higher harmonics (multiples) of the cyclotron frequency can also be used in principle. (09 Oct 1997) |
| electron diffraction | <technique> The phenomenon, or technique of producing diffraction patterns through the incidence of electrons upon matter. (05 Aug 1998) |
| electron donor | A molecule or compound that gives up electrons in an oxidation-reduction reaction. (09 Oct 1997) |
| electron gun | <apparatus> A cathode/anode device intended to produce a stream of electrons. Also used inside a video camera tube and monitor picture tube that contains a heated cathode. Electrons emitted by the gun are focused to produce the scanning beam. (05 Aug 1998) |