Varying Levels Of Protection Research Articles

Efficacy of AIDS vaccine strategies in nonhuman primates

Since only a limited number of vaccines can be tested for efficacy in phase 3 studies in humans, a filter is needed allowing selection of the most promising ones. Although differences between HIV infection in humans and simian immunodeficiency virus infection in nonhuman primates (NHP) might limit the predictive value of these models, comparative efficacy studies in NHPs could facilitate ranking of vaccine candidates. While various forms of protein vaccines failed to induce consistent protection, live-attenuated vaccines, DNA vaccines and viral vector vaccines provided various levels of protection in NHPs. However, variability in the experimental models limits the conclusions that can be drawn with respect to the relative efficacy of vaccines not tested in the same experiment. Therefore, better standardization is an urgent necessity in order to exploit the full potential of nonhuman primate models in AIDS vaccine development.

Innovative corrosion mitigation solutions for existing concrete structures

Reinforced concrete has developed a strong reputation as a versatile, durable and economical building material. However, when concrete is subjected to aggressive environmental conditions, repair and maintenance is required over time to keep the structure in a serviceable and safe condition. In recent years, the range of corrosion mitigation systems provides engineers and owners with more options to mitigate corrosion and extend the service life of existing structures. Various types of electrochemical corrosion mitigation systems (including electrochemical treatments, impressed current cathodic protection, and galvanic protection) and an overview of the various levels of protection offered by electrochemical corrosion mitigation technologies (corrosion prevention, corrosion control, cathodic protection and corrosion passivation) is presented. Project reviews detail the application of certain specialised technologies including electrochemical treatments (re-alkalisation and chloride extraction), targeted corrosion control with embedded galvanic anodes, and galvanic cathodic protection using embedded strip anodes and humectant-activated zinc metalising.

Risk-Based Design of Bridge Scour Countermeasures

HYRISK was originally developed to prioritize bridges with unknown foundations to determine where to spend limited resources to investigate those bridges. It was later modified to prioritize bridges of any type for scour evaluations where there are limited resources for the evaluations each year. The model is based on information that can be read from the National Bridge Inventory and accounts for average daily traffic, detour lengths, value of lost time, risks associated with scour at various types of foundations, bridge condition, bridge geometry, and bridge age. The model can readily be modified for use as a decision tool to select various levels of countermeasures for a bridge that has already been evaluate and determined to be scour critical for some probability flood event. For that application, the model can use the determined probability of failure and does not need to rely on the assumed risks for various foundation types. The model will need to account for the risk of loss of life on the basis of recent experience. The bridge owner will provide information on the expected life of the bridge and the costs of various levels of protection. The model will determine the optimum level of protection for the bridge and the maximum expenditures that should be accepted to increase the level of protection.

Determining the Level of Ship Protection

AbstractThe types and levels of protection provided in naval ships have always been determined by the judgement of experienced naval officers in a way that is basically external to the main analysis/design loop. A major consequence has been an inability to demonstrate a clear need for a particular level of protection, with the result that important protection features have been eliminated to reduce cost.This paper outlines a methodology for bringing ship protection inside the main loop and determining its characteristics as an integrated element of a ship design. The level of protection is established as a natural consequence of the ship's mission requirements, and no separately stated requirements for protection are needed.Two concepts are introduced for achieving this. The first is a life cycle, measure of ship effectiveness that takes account of the ship's entire service life, including periods when operating in a degraded condition in combat or unavailable for service while being repaired or modernized. The second is the concept of “battle cost.” Battle costs are defined as the hypothetical future costs of weapons expended and ship damage and personnel casualties sustained, plus other related costs, as a ship engages in battle in the course of its service life. These devices, within the system analysis framework, make it possible to estimate both effectiveness and cost implications of providing various levels of protection in the ship—and thus to derive better cost‐effectiveness measures for comparing ship alternatives and selecting the best.

Determining the Level of Ship Protection

ABSTRACT The types and levels of protection provided in naval ships have always been determined by the judgment of experienced naval officers in a way that is basically external to the main analysis/design loop. A major consequence has been an inability to demonstrate objectively a clear need for a particular level of protection, with the result that important protection features have been eliminated to reduce cost.This paper outlines a methodology for bringing ship protection inside the main loop and determining its characteristics as an integrated element of a ship design. The level of protection is established as a natural consequence of the ship's mission requirements, and no separately stated requirements for protection are needed.Two concepts are introduced for achieving this. The first is a life cycle measure of ship effectiveness that takes account of the ship's entire service life, including periods when operating in a degraded condition in combat or unavailable for service while being repaired or modernized. The second is the concept of “battle cost.” Battle costs are defined as the hypothetical future costs of weapons expended and ship damage and personnel casualties sustained, plus other related costs, as a ship engages in battle in the course of its service life. These devices, within the systems analysis framework, make it possible to estimate both effectiveness and cost implications of providing various levels of protection in the ship—and thus to derive better cost‐effectiveness measures for comparing ship alternatives and selecting the best.

Developing a river protection policy for Texas: Paddling upstram against the current

State-level wild and scenic river programs currently provide varying levels of protection to over 450 river segments covering 15,500 river miles in 32 states. Collectively, these state-level programs have surpassed the federal system under the National Wild and Scenic Rivers Act in terms of both the number of river miles protected and the quality of protection provided. Content analysis and location quotient analyses are used to evaluate the programmatic features of existing state programs and the spatial distribution of river mileage protected across the United States. Results of the analyses were applied to developing policy recommendations for river protection in Texas, where nine previous legislative attempts to establish a river program have failed. Policy recommendations focus on nurturing local support for watershed and greenway protection programs, and working to overcome riparian landowner fears regarding trespass, littering, and vandalism. © 1997 John Wiley & Sons, Inc.

Thermotolerance and nuclear protein aggregation: protection against initial damage or better recovery?

Heat-induced nuclear protein aggregation and subsequent disaggregation were measured in nonpreheated and preheated (thermotolerant) HeLa S3 cells. The effect of thermotolerance on the formation of and recovery from heat-induced nuclear protein aggregates was related to the cellular levels of hsp27, hsp60, hsp70, hsc70, and hsp90. Cells heated at different time points after the thermotolerance trigger showed various levels of protection against heat-induced nuclear protein aggregation. This protection, however, did not parallel the development and decay of thermotolerance on cell survival. The protection was maximal when the thermotolerance level already had started to decay. The level of protection against nuclear protein aggregation did however parallel the cellular level of hsp70 indicating that hsp70 may be involved in this process. At all stages during the development and decay, thermotolerant cells showed a more rapid recovery (disaggregation) from the heat-induced nuclear protein aggregates than non-thermotolerant cells. The rates of disaggregation during development and decay of thermotolerance paralleled the cellular levels of hsp27 suggesting that hsp27 is somehow involved in this recovery process from heat-induced nuclear protein aggregates. The total cellular levels of none of the individual hsp's completely correlate with development and decay of thermotolerance, indicating that overexpression of any of these hsp's alone does not determine the level of thermotolerance. Clonogenic cell survival paralleled the rates of disaggregation, leading to the notion that recovery processes are the most important determinant for the thermotolerant state of HeLa S3 cells. The best correlation with clonogenic survival was found when both initial aggregation and subsequent disaggregation were taken into account, suggesting that the combined action of various hsp's in these two processes have to be included in thermotolerance development and decay.

The role of high ionic concentrations in protection against X-irradiation.

Various levels of protection against x-irradiation damage in bacteriophage T1 may be obtained by the addition of inorganic salts to the aqueous virus suspensions during irradiation. The highest survival values are obtained with the nitrite salts, and their protective power is attributed primarily to their function as reducing agents. The nitrate ion shows greater protection than the corresponding sulfate or chloride ions. This may be due in part to the lower energy level of the nitrate ion, by reason of resonance. Since greater expenditure of incident energy is required to raise the ion from the ground state, the energy thus dissipated may be ineffective in the inactivation of virus particles. The ammonium salts exhibit protection of a different order of magnitude from that of the metallic salts. It is postulated that NH(4) (+) protects in a threefold way: (a) dehydration, (b) reduction, in which the ammonia is oxidized to nitrite and the nitrite to nitrate, and (c) stabilization of the virus protein. Metallic salts likewise protect, but a point of maximum protection is reached in lower concentrations than in the case of the ammonium salts. After this maximum protection is reached, there is a rapid decline in survival with increased concentration. This prevents protection of the order of magnitude that can be obtained with the ammonium salts. It is postulated that a specific cationic interaction with the phage may be responsible for the decreased protection. Bacteriophage is protected during x-irradiation by an alkaline pH, in the case of NH(4)OH. This protection could not be produced with NaOH, presumably because of the greater hydrolysis of the protein components of the virus particle in solutions of NaOH, whereas NH(4)OH stabilizes the protein.