Nitrification parameter measurement for plant design: experience and experimental issues with new methods.

Nitrification kinetics are important for process design, optimization, and capacity rating of activated sludge wastewater treatment plants. A Water Environment Research Foundation (WERF) project on Methods for Wastewater Characterization in Activated Sludge Modeling (WERF, 2003) focused significantly on the development of procedures for measuring the nitrifier maximum specific growth rate, micro(AUT). In addition, the importance of (and lack of data for) the nitrifier decay rate, b(AUT), was identified. This paper describes three bench-scale methods for measuring micro(AUT): the Low F/M SBR, Washout and High F/M methods. During the WERF project, the importance of pH and temperature control was investigated briefly; this paper summarizes further experimental work performed to address these issues. A summary of micro(AUT) measurements in a number of locations and using the different measurement techniques is provided.     

Effects of poly(acrylic acid) and poly(ethylene oxide) adsorption on the stability of alumina suspension

The effect of adsorbed polymer on the stability of alumina suspension was investigated. Poly(ethylene oxide) (PEO), poly(acrylic acid) (PAA) and similar kinds of polymer salts were used as a dispersant. The amount of polymer adsorbed on alumina surface and the suspension stability was measured. The pH, molecular weight, and concentration were considered as experimental parameters. PEO shows low affinity on the alumina surface while PAA has high affinity. In the case of PAA adsorption, the surface charge change by polymer adsorption influences suspension stability strongly, but not in the case of PEO adsorption. In simultaneous adsorption of PEO and PAA, the PAA concentration was fixed and PEO concentration was varied. The stability of suspension increased with increasing PEO concentration, and this is partly due to the steric stabilization by adsorption of PAA-PEO complex or adsorption of PEO through pre-adsorbed PAA and the depletion effect of non-adsorbed polymer. Suspension adsorbing sodium salts of PAA and poly(methacrylic acid) (PMA) each showed similar stability. But, when the PEO and these kinds of salts were added together to the suspension, the one with PAA sodium salt could keep a higher stability even with lower molecular weights of PEO compared with suspension with PMA sodium salt.     

Cryptography during the French and American Wars in Vietnam

After Vietnam’s Declaration of Independence on 2 September 1945, the country had to suffer through two long, brutal wars, first against the French and then against the Americans, before finally becoming a unified country free of colonial domination in 1975. The authors’ purpose is to examine the role of cryptography in those two wars. Despite the far greater technological resources of their opponents, the communications intelligence specialists of the Vi?t Minh, the National Liberation Front, and the Democratic Republic of Vietnam had considerable success in both protecting Vietnamese communications and acquiring tactical and strategic secrets from the enemy. Perhaps surprisingly, in both wars there was a balance between the sides. Generally speaking, cryptographic knowledge and protocol design were at a high level at the central commands, but deployment for tactical communications in the field was difficult, and there were many failures on all sides.     

Review of Revitalizng retirement: Reshaping your identity, relationships, and purpose.

Reviews the book, Revitalizng retirement: Reshaping your identity, relationships, and purpose by Nancy K. Schlossberg (2009). Therapists, counsellors, and life coaches working with older middle-age adults will find this handbook to happiness in retirement a useful working tool. The author introduces the book by stating that some content resembles notes she resurrected from a freshman undergraduate lecture on personal development; accordingly, both the format and the issues discussed in this book generalise to life span motivational needs, but the intended focus is on the transition to retirement. As a result, this book would make a useful tool for a support group or workshop on psychosocial transitions in postemployment life, with some limitations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inflow shortages in deregulated power markets — Reasons for concern?

In many countries hydropower constitutes a large share of the electricity producing capacity. In the earlier regulated electricity markets, production capacities exceeded demand due to security of supply concerns. The present deregulated markets base investments upon profitability alone, and security of supply issues are claimed to be less important. Market operators trust the pricing mechanism in competitive markets to clear. Then low inflow constitutes a less problem. Several markets, both under regulated and deregulated regimes, have faced serious droughts. Some of them have experienced problems with market clearance (Chile, Brazil, California) while other markets functioned well (The Nordic market). Important features to the market response are the flexibility of demand, the pattern of inflow shortage, the storage capacities, the possibility of trade between regions with different production technologies, and the market design and concentration. We apply an empirical based market model to simulate the effects under two inflow shortage scenarios in an international market with combined hydro and thermal capacities and restricted transmission capacities. We compare the scenarios with actual events and show that the model and the real market outcome are comparable. The simulations do not reveal any problems with the functioning of the market, which should calm down the anxiousness about security of supply in deregulated markets with stochastic energy supply.     

Mixed effect modeling of sumatriptan pharmacokinetics during drug development. I: Interspecies allometric scaling

A sample of 22 subjects was studied from a population of adults who had suffered from bacterial meningitis in childhood. Audiovestibular, oculomotor and neuropsychological investigations were performed and quality of life was assessed. An age-matched control group of 20 subjects was recruited. In the meningitis group, nine subjects had abnormal pure tone audiograms. One was previously undiagnosed and a progression was found in four. There was an overrepresentation of subclinical vestibular pathology (6 out of 9 (67%)) in this group. Audiovestibular test results showed a peripheral pattern and oculomotor tests were normal. The quality of life scores of those with hearing loss were significantly higher than those in the control group. Neuropsychological tests of brain dysfunction were abnormal in six out of 22 (27%) who had recovered from meningitis. The prevalence of such dysfunctions was not related to audiovestibular disorder. The quality of life scores of those with brain dysfunctions were similar to those of the control group. The findings of reduced auditory memory and tone level perception in four out of 22 (18%), suggest that lesions of central auditory pathways may follow from bacterial meningitis. The results support the idea that inner ear damage is the major cause of hearing loss after bacterial meningitis. Despite the absence of brainstem involvement, central nervous system lesions with disturbed auditory processing and language functions can be of significance. The high frequency of discrete brain dysfunctions indicate that a thorough neuropsychological investigation is required after bacterial meningitis.