Implementation issues in product line scoping

Often product line engineering is treated similar to the waterfall model in traditional software engineering, i.e., the different phases (scoping, analysis, architecting, implementation) are treated as if they could be clearly separated and would follow each other in an ordered fashion. However, in practice strong interactions between the individual phases become apparent. In particular, how implementation is done has a strong impact on economic aspects of the project and thus how to adequately plan it. Hence, assessing these relationships adequately in the beginning has a strong impact on performing a product line project right. In this paper we present a framework that helps in exactly this task. It captures on an abstract level the relationships between scoping information and implementation aspects and thus allows to provide rough guidance on implementation aspects of the project. We will also discuss the application of our framework to a specific industrial project

Multigraded Castelnuovo-Mumford Regularity

We develop a multigraded variant of Castelnuovo-Mumford regularity. Motivated by toric geometry, we work with modules over a polynomial ring graded by a finitely generated abelian group. As in the standard graded case, our definition of multigraded regularity involves the vanishing of graded components of local cohomology. We establish the key properties of regularity: its connection with the minimal generators of a module and its behavior in exact sequences. For an ideal sheaf on a simplicial toric variety X, we prove that its multigraded regularity bounds the equations that cut out the associated subvariety. We also provide a criterion for testing if an ample line bundle on X gives a projectively normal embedding.Comment: 30 pages, 5 figure

Synthetic control of a fitness tradeoff in yeast nitrogen metabolism

Background: Microbial communities are involved in many processes relevant to industrial and medical biotechnology, such as the formation of biofilms, lignocellulosic degradation, and hydrogen production. The manipulation of synthetic and natural microbial communities and their underlying ecological parameters, such as fitness, evolvability, and variation, is an increasingly important area of research for synthetic biology. Results: Here, we explored how synthetic control of an endogenous circuit can be used to regulate a tradeoff between fitness in resource abundant and resource limited environments in a population of Saccharomyces cerevisiae. We found that noise in the expression of a key enzyme in ammonia assimilation, Gdh1p, mediated a tradeoff between growth in low nitrogen environments and stress resistance in high ammonia environments. We implemented synthetic control of an endogenous Gdh1p regulatory network to construct an engineered strain in which the fitness of the population was tunable in response to an exogenously-added small molecule across a range of ammonia environments. Conclusion: The ability to tune fitness and biological tradeoffs will be important components of future efforts to engineer microbial communities

Catastrophic Risk Evaluation

A body of empirical evidence has shown that many managers would welcome new ways of highlighting catastrophic consequences, as well as means to evaluating decision situations involving high risks. When events occur frequently and their consequences are not severe, it is relatively simple to calculate the risk exposure of an organisation, as well as a reasonable premium when an insurance transaction is made. The usual methods rely on variations of the principle of maximising the expected utility (PMEU). When, on the other hand, the frequency of damages is low, the situation is considerably more difficult, especially if catastrophic events occur. When the quality of estimates is poor, e.g., when evaluating low-probability/high-consequence risks, the customary use of quantitative rules together with overprecise data could be harmful as well as misleading. This work extends the risk evaluation process by the integration of procedures for handling vague and numerically imprecise probabilities and utilities. The shortcomings of PMEU, and of utility theory in general, can in part be compensated for by the introduction of risk constraints. We point out some problematic features of the evaluations performed using utility theory. We also criticise the demand for precise data in situations where none is available. As an alternative to traditional models, we suggest a method for the evaluation of risks when the information at hand is numerically imprecise. The method includes procedures that allow for interval statements and comparisons, and thereby it does not require the use of numerically precise statements of probability, cost, or utility in a general sense. In order to attain a reasonable level of security, and because it has been shown that managers tend to focus on large negative losses, it is argued that a risk constraint should be imposed on the analysis. The strategies are evaluated relative to a set of such constraints considering how risky the strategies are

Participatory governance of energy transition in Jordan: a way to address existing uncertainties in decision- making processes

Energy transition towards a more significant share of domestically generated resources will inevitably lead to a societal transformation, which will affect the interests of existing and emerging electricity generation industries and other stakeholders. To be sustainable, such transition should also address issues of environmental protection and contribution to socio-economic development. A reasonable assumption is that human factors play an important role in energy transition. These human factors include perceptions of different risks connected with technological deployment, as well as views about benefits and impacts generated by different technologies. We present a multi-stakeholder multi-criteria approach to assess the relevance of the Jordan’s electricity generation technologies against a set of criteria under uncertainty, which reflect environmental, social and economic components of sustainable development. The results show that the discourse in the Jordanian society is currently dominated by economic rationality, such as electricity costs, supported by concerns about safety during operation and maintenance of electricity generation power plants. The results also show the strong desire of all stakeholder groups to have an opportunity to engage in decision-making processes on energy transition rather than purely to compensate local communities for the installation of electricity generation and transmission technologies

Sistemas Conservacionistas de Preparo do Solo e Implicações no Ciclo do Carbono.

bitstream/CNPDIA/10460/1/DOC12_2004.pd

Spin dynamics and magnetic-field-induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment

The exciton spin dynamics are investigated both experimentally and theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect band gap and a type-II band alignment. The magnetic-field-induced circular polarization of photoluminescence, $P_c$, is studied as function of the magnetic field strength and direction as well as sample temperature. The observed nonmonotonic behaviour of these functions is provided by the interplay of bright and dark exciton states contributing to the emission. To interpret the experiment, we have developed a kinetic master equation model which accounts for the dynamics of the spin states in this exciton quartet, radiative and nonradiative recombination processes, and redistribution of excitons between these states as result of spin relaxation. The model offers quantitative agreement with experiment and allows us to evaluate, for the studied structure, the heavy-hole $g$ factor, $g_{hh}=+3.5$, and the spin relaxation times of electron, $\tau_{se} = 33~\mu$s, and hole, $\tau_{sh} = 3~\mu$s, bound in the exciton.Comment: 17 pages, 16 figure