Comprehension of object-oriented software cohesion: The empirical quagmire

Chidamber and Kemerer (1991) proposed an object-oriented (OO) metric suite which included the Lack of Cohesion Of Methods (LCOM) metric. Despite considerable effort both theoretically and empirically since then, the software engineering community is still no nearer finding a generally accepted definition or measure of OO cohesion. Yet, achieving highly cohesive software is a cornerstone of software comprehension and hence, maintainability. In this paper, we suggest a number of suppositions as to why a definition has eluded (and we feel will continue to elude) us. We support these suppositions with empirical evidence from three large C++ systems and a cohesion metric based on the parameters of the class methods; we also draw from other related work. Two major conclusions emerge from the study. Firstly, any sensible cohesion metric does at least provide insight into the features of the systems being analysed. Secondly however, and less reassuringly, the deeper the investigative search for a definitive measure of cohesion, the more problematic its understanding becomes; this casts serious doubt on the use of cohesion as a meaningful feature of object-orientation and its viability as a tool for software comprehension

Values, norms, transactions and organizations

This paper may be considered an essay on metaeconomics, since it deals with the meaning of several concepts often left undefined, or very briefly defined in economic theories. These concepts are the following: value including the values of things and moral values, social norms or institutions, social power, goods and services, transactions and organizations (firms, and others). The paper starts by proposing a general concept of value, encompassing both the value of things and moral values. From this concept it proceeds to the definition of six different types of values of things and moral values and to the concept of value transformation process of things which includes all the operations dealt with in economic theory as well as many other human actions. The last part of the paper starts with the distinction between moral values and social norms (or institutions) and the roles of social power and human organization in connecting the domains of morality and social normativity. The paper proceeds by distinguishing different types of norms, including possession norms which are important for defining the concepts of goods and services and transaction processes.

Participation of non-industrial private forest owners in National Forest Programmes: a discrete choice model for Northern Portugal

In countries where private forest ownership is very important, knowledge of the behaviour of private forest owners is useful for the design and implementation of successful forest policies. This applies to Portugal where 86 % of the forest lands are private property. This paper presents a study carried out in a region of the Northern part of the country covered by a local forest owners’ association. Based on individual data about the members of this association concerning some of their characteristics (implementation of publicly subsidised afforestation projects, size of the forest holdings, number of forest holdings belonging to the same owner and distance between the permanent residence of the owner and his forest holdings), a multinomial logit model is estimated for the probabilities of participation on public incentive schemes to finance individual and grouped afforestation projects.non industrial private forest owners, afforestation projects, public incentives

Intergenerational transfers in rural households: A game theoretical approach

The household membership decision is viewed as a “research project” where the offspring invests in human and non human capital to influence the probability of finding an alternative to the parental household. The problem is formulated as a differential game between a selfish offspring and altruistic parents. The solution is consistent with facts” such as the “flexibility of inheritance systems” and the “generational fragmentation” of the family property when the economic opportunities expand outside the parental household.intergenerational transfers, rural households, game theory

Identifying and modeling patterns of tetrapod vertebrate mortality rates in the Gulf of Mexico oil spill

The accidental oil spill in the Gulf of Mexico in 2010 has caused perceptible damage to marine and freshwater ecosystems. The large quantity of oil leaking at a constant rate and the long duration of the event caused an exponentially increasing mortality of vertebrates. Using data provided by NOAA and USFWS, we assessed the effects of this event on birds, sea turtles, and mammals. Mortality rates (measured as the number of carcasses recorded per day) were exponential for all three groups. Birds were the most affected group, as indicated by the steepest increase of mortality rates over time. For sea turtles and mammals, an exponential increase in mortality was observed after an initial delay. These exponential behaviors are consistent with a unified scenario for the mortality rate for tetrapod vertebrates. However, at least for mammals, pre-spill data seem to indicate that the growth in the mortality rate is not entirely a consequence of the spill.Comment: 4 pages, 1 figur

Evolution of a sandpile in a thick flow regime

We solve a one-dimensional sandpile problem analytically in a thick flow regime when the pile evolution may be described by a set of linear equations. We demonstrate that, if an income flow is constant, a space periodicity takes place while the sandpile evolves even for a pile of only one type of particles. Hence, grains are piling layer by layer. The thickness of the layers is proportional to the input flow of particles $r_0$ and coincides with the thickness of stratified layers in a two-component sandpile problem which were observed recently. We find that the surface angle $\theta$ of the pile reaches its final critical value ($\theta_f$) only at long times after a complicated relaxation process. The deviation ($\theta_f - \theta$) behaves asymptotically as $(t/r_{0})^{-1/2}$. It appears that the pile evolution depends on initial conditions. We consider two cases: (i) grains are absent at the initial moment, and (ii) there is already a pile with a critical slope initially. Although at long times the behavior appears to be similar in both cases, some differences are observed for the different initial conditions are observed. We show that the periodicity disappears if the input flow increases with time.Comment: 14 pages, 7 figure