Short tracks

Figures 3.3 and 3.4 show sections of low-LET tracks chosen to show a blob and a short track, respectively. Numerically, spurs dominate over blobs and short tracks. On the other hand, the fraction of energy held up in the extraspur entities is significant, and in a real sense these represent LET effect in electron tracks.

FIGURE 3.4 Section of a low-LET track selected to show a short track. On high-energy electron tracks, spurs outnumber short tracks by about 500 1. 

FIGURE 3.5 Energy partition among the track entities (spurs, blobs, and short tracks) as a function of electron energy in liquid water. Data from Pimblott et at. (1990), with permission of Am. Chem. Soc. ... 

Tritiated water in solution has been used in radiolysis scavenger studies are rare, but a few are known (Appleby and Gagnon, 1971 Lemaire and Ferradini, 1972). Electrons from the /3-decay of tritium have a broad spectrum between 0 and 18 KeV, with a peak at 5.5 KeV. Over this distribution, the energy is partitioned between spurs, blobs, and short tracks as 0.2 5 0.08 0.67, which... 

Figure 4 of Mozumder (1971) compares the kinetics of neutralization in an isolated ion-pair, a spherical blob, and a short track. For the isolated ion-pair there is vey little recombination until 5 x 10 u s, but most recombination is over by -Ins. The main difference in the recombination kinetics is between the isolated and multiple ion-pair cases. There is not such a great difference among the different multiple ion-pair blobs or short tracks. In the multiple-ion-pair cases, the neutralization is gradual and much faster than that in the isolated ion-pair case at short times. However, this could be an artifact of the model predicated by close proximity of the positive ions having essentially zero mobility (vide infra). 

These results imply that the use of the representative single ion-pair distribution in the ionization produced by low-LET irradiation in liquid hydrocarbons can be approximately justified even though the track itself has considerable contribution from multiple-ion-pair spurs and short tracks. It also means that even in the case of an isolated ion-pair, the long-time limit of the existence probability is perturbed by the long-range coulombic field. 

Electron Energy Isolated Spurs Short Tracks Blobs... 

Intratrack Reactions. Earlier It was noted that chemical reactions could occur between the species before they could diffuse away from each other. In the case of Irradiated water, for example, this will result In a greater yield of the molecular species, H2 and H202, and a lower yield of the radical species, 0H, e and H. Additionally, the amount of solute present In a short track or blob Is limited and this may conceivably alter the course of reactions. In other respects, once the radlolytlc species diffuse away from their place of origin Into the bulk of the solution, they follow conventional solution behaviour. However, even In homogeneous solutions there will be differences attributable to the three track entitles because of differences In the yields of molecular products formed by reactions between primary radicals and the yields of radical species which are able to escape out of the tracks. Thus It Is possible to consider the overall yield of products as the sum of the Individual yields from the three track entitles, duly adjusted for the relative contributions from each, giving a weighted average equivalent to the observed experimental yields (10,19). 

Such a presentation of a fast electron track as a set of spurs, blobs, and short tracks is widely used in radiation chemistry for describing the processes that occur in a condensed medium exposed to electron or gamma radiation.7 However, this presentation is not the only one there is. Other possible approaches are discussed in Ref. 305, where, in particular, the authors note that the most general description of track structures is the one using correlation functions. 

Minimum rhabdomyolysis—non-myoglobinuric acute renal failure due to exercise-induced acute renal failure—ALPE (acute renal failure with severe loin pain and patchy renal ischemia after anaerobic exercise) after sprint, short track event such as 200-m race, etc. 

Short track Soccer Swimming Running Baseball Bicycle race Physical training Marathon Weightlifting Skiing Press-ups/sit-ups Quarrel Flying a light plane... 

If a renal hypouricemia patient with a serum uric acid level of l.Omg/dl or less wishes to join an athletics sports team (short track sprint) at school, a physician should instruct them to change to other activities. If a patient participates in a track event at an athletics meeting, a physician should instruct them to comply with the preventive methods described above. 

Special Regulations Speed Skating and Short Track Speed Skating 2004, ISU, 2004, 60. 

A more refined model was then presented by Mozumder and Magee [11]. It takes into account glancing and knock-on collisions and gives a complete picture of the track. Many new entitites called blobs, short tracks and branch tracks were defined in order to obtain this picture. 

Fig. 6. Energy partition between spurs, blobs, and short tracks for electrons in water. Ordinate gives the fractional energy in a given form through all generations as a function of primary energy [10].

The basic assumption is that water is decomposed by radiation into eaq, OH, and H30+, which are formed inhomogeneously in spurs. In these spurs, which are spherical, with a diameter of 10-40 A., several pairs of these radicals are initially formed where their initial concentration is very high (0.1-1M). The distance between spurs depends on the LET of the radiation. For y-, x-rays, or fast electrons most of the spurs are isolated, and only a small fraction overlaps and forms blobs or short tracks (56). At high LET radiation, the overlapping of the spurs produces cylindrical tracks. 

A survey is given of the theory of the physical stage of radiolysis. Using the optical approximation to cross sections for the interaction between fast electrons and molecules, expressions have been derived for the yield g° of primary optical activations, and for the total absorbed energy Qtot It is shown that the total yield g of primary activations is conveniently discussed as a sum g° + gs, where the first term includes the action of fast electrons, while g8 describes the action of slow electrons (kinetic energy less than about 100 e.v.) on molecules of the medium. This approach is compared with Platzmans considerations on primary yields and the differences are pointed out. Finally, theoretical results of the present approach are applied to the analysis of the initial structure of the track of a fast electron, consisting of spurs, blobs, and short tracks. 

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