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Transition Patterns (transition + pattern)
Selected AbstractsDynamics of Benzene and Toluene Degradation in Pseudomonas putida F1 in the Presence of the Alternative Substrate SuccinateENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2007I. Rüegg Abstract In batch and continuous culture, the regulation of benzene and toluene degradation by Pseudomonas putida,F1 was investigated in the presence of the alternative carbon and energy source succinate. In batch culture, benzene and toluene were used simultaneously, whereas succinate suppressed benzene consumption under carbon excess conditions resulting in diauxic growth. In carbon-limited continuous culture mixed substrate growth was observed. Since in nature low substrate concentrations and ever changing conditions prevail, this paper focuses on the dynamics of benzene/toluene degradation, biomass synthesis, and the regulation of benzene/toluene-degrading enzymes in cultures growing continuously at a dilution rate of 0.1,h,1, when shifting the supply of the carbon and energy source from succinate to various mixtures of succinate and benzene/toluene, or to benzene only. When the succinate concentration was kept constant (1.25,mM) and the medium was supplemented with benzene (2,mM), growth with benzene began already two hours after the shift. In contrast, replacing succinate with benzene only led to a wash out of biomass for more then ten hours, before biomass production from benzene started. A striking and reproducible transition pattern was observed for all shifts where the succinate concentration was reduced or succinate was omitted. After an initial period of biomass production from benzene, the culture collapsed and a wash-out of biomass was observed. However, this wash-out was not accompanied by an increase in benzene in the cultivation liquid, indicating a benzene uptake without conversion into biomass. Another possibility is that in phases of low biomass concentrations, cells were only able to use the low amounts of benzene/toluene dissolved in the cultivation liquid yielding low biomass concentrations whereas in phases of high biomass concentrations, they were able to rapidly utilize the aromatic solvents so that additional benzene from the gas phase diffused into the cultivation liquid resulting in more biomass production. In most cases, growth resumed again after 10 to 80,h. Currently, the reasons for the decrease in biomass after the first rise are unknown. However, several indications rule out intoxication of the cells by either the solvents benzene or toluene themselves, or by toxic degradation intermediates, or by-products. [source] Pension Valuation Under Uncertainties: Implementation of a Stochastic and Dynamic Monitoring SystemJOURNAL OF RISK AND INSURANCE, Issue 2 2002Shih-Chieh Chang Financial soundness and funding stability are two critical issues in pension fund management. First, we construct a generalized stochastic model to monitor the solvency risk and cash flow dynamics of the defined benefit pension plan. A semi-Markov process proposed by Dominicis et al. (1991) and Janssen and Manca (1997) is employed in structuring the transition pattern of the plan's population, and the economic-based factors are generated through plausible stochastic processes. Modifications according to classification and movements of the plan member and the plan's turnover pattern are also employed to improve its practical usefulness. Then the actuarial valuations, cash flow analyses, and workforce projection are performed and investigated. Second, we explicitly formulate the plan dynamics and implement the proposed mechanism into a risk management framework for pension management. By employing the stochastic and dynamic approach, the cost factors can be monitored throughout the valuation process. Third, we outline the procedure of implementing the proposed methodology into a monitoring system. Finally, the Taiwan Public Employees Retirement System is simplified to illustrate techniques in achieving risk management goals. [source] Causes and Consequences of Unexpected Educational Transitions in SwitzerlandJOURNAL OF SOCIAL ISSUES, Issue 1 2008Markus P. Neuenschwander The present study examines transition patterns of Swiss secondary and tertiary school students. Switzerland's highly canalized education system allows us to test how tracking affects person,environment fit of students for students who choose a normative versus unexpected downward transition pattern. In addition, we investigate how self-efficacy expectations and personal values affect an unexpected transition choice. Results indicate that students with strong expectancies and personal values can oppose institutional norms and chart their own academic course; however, these students are less likely to perceive a good fit between their own interests and competencies and institutional demands after the transition. Our findings underscore the importance of developmentally appropriate educational environments and systems permeable enough to adapt to developing students' changing interests. [source] Use of Process Data To Assess Chromatographic Performance in Production-Scale Protein Purification ColumnsBIOTECHNOLOGY PROGRESS, Issue 2 2003Tina M. Larson Transition analysis was performed on production-scale chromatography data in order to monitor column performance. Analysis of over 300 transitions from several different chromatography operations demonstrated the utility of the techniques presented. Several of the transitions analyzed occurred on columns with known integrity breaches. The techniques proved sensitive for detection of these breaches. Seven transition calculations are presented, which were combined to produce a single overall integrity value for each column. In addition, principal components analysis (PCA) was used to detect shifts in the transition pattern, including those attributed to integrity breaches. Besides detection of integrity breaches, transition analysis proved useful in monitoring column efficiency over multiple column uses. [source] Song Learning in Wild and Domesticated Strains of White-Rumped Munia, Lonchura striata, Compared by Cross-Fostering Procedures: Domestication Increases Song Variability by Decreasing Strain-Specific BiasETHOLOGY, Issue 5 2010Miki Takahasi Song diversity results from the interactions between natural selection, sexual selection, and individual learning. To understand song diversity, all three factors must be considered collectively, not separately. Bengalese Finches were domesticated about 250 yr ago. Their courtship songs have become different from their ancestor, the White-rumped Munia. Bengalese Finches sing songs with complex note-to-note transition patterns and with acoustically diverse song notes while White-rumped Munias sing songs with fixed note sequence and mostly broad band song notes. Bengalese Finches were selected for domestication based on their good parenting ability, not their songs, but this artificial selection has nonetheless affected their songs. To test whether divergence occurred not only in the song phenotypes but also in the genetic basis for predisposition of strain specific song learning, we conducted a cross-fostering experiment between Bengalese Finches and White-rumped Munias. In both strains, song learning was affected by rearing condition: the acoustical feature and transition patterns followed those of the foster fathers. However, the accuracy of song learning differed between the wild and the domesticated strains: sharing of song note between sons and tutors in Finches was not very accurate regardless of the tutor, while Munias were highly accurate in copying Munia songs but often omitted song elements from Finch fathers. These results suggest that White-rumped Munias are strongly constrained to learn their own strain's song, and that this constraint was relaxed in the Bengalese Finch by domestication. [source] Causes and Consequences of Unexpected Educational Transitions in SwitzerlandJOURNAL OF SOCIAL ISSUES, Issue 1 2008Markus P. Neuenschwander The present study examines transition patterns of Swiss secondary and tertiary school students. Switzerland's highly canalized education system allows us to test how tracking affects person,environment fit of students for students who choose a normative versus unexpected downward transition pattern. In addition, we investigate how self-efficacy expectations and personal values affect an unexpected transition choice. Results indicate that students with strong expectancies and personal values can oppose institutional norms and chart their own academic course; however, these students are less likely to perceive a good fit between their own interests and competencies and institutional demands after the transition. Our findings underscore the importance of developmentally appropriate educational environments and systems permeable enough to adapt to developing students' changing interests. [source] Stochastic modeling of usage patterns in a web-based information systemJOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 7 2002Hui-Min Chen Users move from one state (or task) to another in an information system's labyrinth as they try to accomplish their work, and the amount of time they spend in each state varies. This article uses continuous-time stochastic models, mainly based on semi-Markov chains, to derive user state transition patterns (both in rates and in probabilities) in a Web-based information system. The methodology was demonstrated with 126,925 search sessions drawn from the transaction logs of the University of California's MELVYL® library catalog system (www.melvyl.ucop.edu). First, user sessions were categorized into six groups based on their similar use of the system. Second, by using a three-layer hierarchical taxonomy of the system Web pages, user sessions in each usage group were transformed into a sequence of states. All the usage groups but one have third-order sequential dependency in state transitions. The sole exception has fourth-order sequential dependency. The transition rates as well as transition probabilities of the semi-Markov model provide a background for interpreting user behavior probabilistically, at various levels of detail. Finally, the differences in derived usage patterns between usage groups were tested statistically. The test results showed that different groups have distinct patterns of system use. Knowledge of the extent of sequential dependency is beneficial because it allows one to predict a user's next move in a search space based on the past moves that have been made. It can also be used to help customize the design of the user interface to the system to facilitate interaction. The group CL6 labeled "knowledgeable and sophisticated usage" and the group CL7 labeled "unsophisticated usage" both had third-order sequential dependency and had the same most-frequently occurring search pattern: screen display, record display, screen display, and record display. The group CL8 called "highly interactive use with good search results" had fourth-order sequential dependency, and its most frequently occurring pattern was the same as CL6 and CL7 with one more screen display action added. The group CL13, called "known-item searching" had third-order sequential dependency, and its most frequently occurring pattern was index access, search with retrievals, screen display, and record display. Group CL14 called "help intensive searching," and CL18 called "relatively unsuccessful" both had third-order sequential dependency, and for both groups the most frequently occurring pattern was index access, search without retrievals, index access, and again, search without retrievals. [source] The Sex Ratio Transition in AsiaPOPULATION AND DEVELOPMENT REVIEW, Issue 3 2009Christophe Z. Guilmoto This article adopts a comparative perspective to review the recent increase in the sex ratio at birth (SRB) across Asia. It first describes and compares the most recent birth statistics in Asia in order to identify commonalities in the gradual rise of SRBs observed from Armenia to South Korea. This comparison provides the basis for identifying specific transition patterns in the changes in SRBs. Their recent rise is then interpreted in a social and historical framework borrowed from fertility decline and based on three preconditions: access to sex-selection technology, preference for male births, and pressure from low fertility. On a broader plane, the process of growing imbalances in the sex composition of the population gives rise to a tragedy of the commons. This article indicates the factors that appear most likely to trigger a turnaround in this transitional demographic situation and to facilitate a return to biologically normal sex ratios in the future. [source] | ||||||||||