| 1. |
- Gunawardena, D., et al.
(författare)
-
Scoop : Decentralized and opportunistic multicasting of information streams
- 2011
-
Ingår i: Proceedings of the Annual International Conference on Mobile Computing and Networking. - New York, NY, USA : ACM. - 9781450304924 ; , s. 169-180
-
Konferensbidrag (refereegranskat)abstract
- We consider the problem of delivering information streams to interested mobile users, leveraging both access to the infrastructure and device-to-device data transfers. The goal is to design practical relaying algorithms that aim at optimizing a global system objective that accounts for two important aspects: first, the user interest in content with respect to its type and delivery time; and, second, resource constraints such as storage and transmission costs. We first examine a set of real-world datasets reporting contacts between users moving in relatively restricted geographic areas (e.g. a city). These datasets provide evidence that significant performance gains can be achieved by extending the information dissemination from one to two hops, and that using longer paths only brings marginal benefits. We also show that correlation of delays through different paths is typically significant, thus asking for system design that would allow for general user mobility. We then propose a class of relaying strategies (referred to as SCOOP) that aim at optimizing a global system objective, are fully decentralized, require only locally observable states by individual devices, and allow for general user mobility. These properties characterize a practical scheme whose efficiency is evaluated using real-world mobility traces.
|
|
| 2. |
- Rojas, Ana Maria, et al.
(författare)
-
Radiosensitisation in normal tissues with oxygen, carbogen and nicotinamide: therapeutic gain comparisons for fractionated X-ray schedules
- 1996
-
Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 39:1, s. 53-64
-
Tidskriftsartikel (refereegranskat)abstract
- METHODS: Radiosensitisation with oxygen, carbogen or nicotinamide alone and oxygen or carbogen combined with nicotinamide was compared in early and late responding normal tissues in rodents. X-ray treatments were delivered as single doses or fractionated schedules of 2 fractions in 1 day, 2, 12 and 36 fractions in an overall time of 12 days and 10 fractions in 5 or 12 days. Acute skin reactions, survival of intestinal crypts, breathing rate, reduction in the packed red-cell volume and clearance of 51Cr-EDTA were used as assays of epidermal, gut, lung and renal damage. RESULTS: Relative to air-breathing mice, carbogen or oxygen produced a small, and not always significant, increase in sensitivity (enhancement ratios < or = 1.15) in gut, lung and kidneys; however, in skin a dose enhancement of 1.2-1.3 was observed. The effect of nicotinamide in air, carbogen or oxygen was studied only in lung and gut. The drug produced variable but generally significant increases in radiosensitisation ( < or = 1.26) in all three gases. Relative to treatments in air, enhancement ratios for nicotinamide alone were usually slightly higher than those observed when either carbogen or oxygen were administered without the drug. With all three modifiers (i.e. oxygen, carbogen, nicotinamide alone or for the drug-gas combinations) there was no significant change in the enhancement ratios observed as the number of radiation dose fractions was varied. CONCLUSIONS: Comparisons with fractionated X-ray studies done previously in rodent tumours indicate that a therapeutic benefit, relative to lung, gut and renal damage, would be observed with oxygen or carbogen alone but not with nicotinamide alone. The greatest gain would be achieved with the combination of carbogen and nicotinamide, with which a benefit was observed even relative to epidermal damage. These results indicate that some decrease in normal tissue tolerance could be observed when using these modifiers in clinical radiotherapy and, although small, the appropriate dose reductions should be considered; caution should be exercised especially when carbogen and nicotinamide are used in conjunction with the more radical accelerated schedules.
|
|
