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

Application of the NASA airborne oceanographic lidar to the mapping of chlorophyll and other organic pigments

Laser fluorosensing techniques used for the airborne measurement of chlorophyll a and other naturally occurring waterborne pigments are reviewed. Previous experiments demonstrating the utility of the airborne oceanographic lidar (AOL) for assessment of various marine parameters are briefly discussed. The configuration of the AOL during the NOAA/NASA Superflux experiments is described. The participation of the AOL in these experiments is presented and the preliminary results are discussed. The importance of multispectral receiving capability in a laser fluorosensing system for providing reproducible measurements over wide areas having spatial variations in water column transmittance properties is addressed. This capability minimizes the number of truthing points required and is usable even in shallow estuarine areas where resuspension of bottom sediment is common. Finally, problems encountered on the Superflux missions and the resulting limitations on the AOL data sets are addressed and feasible solutions to these problems are provided

Object-oriented cohesion as a surrogate of software comprehension: An empirical study

The concept of software cohesion in both the procedural and object-oriented paradigm is well known and documented. What is not so well known or documented is the perception of what empirically constitutes a cohesive 'unit' by software engineers. In this paper, we describe an empirical investigation using object-oriented (OO) classes as a basis. Twenty-four subjects (drawn from IT experienced and IT inexperienced groups) were asked to rate ten classes sampled from two industrial systems in terms of their overall cohesiveness; a class environment was used to carry out the study. Four key results were observed. Firstly, class size (when expressed in terms of number of methods) did not tend to influence the perception of cohesion by any subjects. Secondly, well-commented classes were rated most highly amongst both IT experienced and inexperienced subjects. Thirdly, the empirical study suggests that cohesion comprises a combination of various class factors including low coupling, small numbers of attributes and well-commented methods, rather than any single, individual class feature per se. Finally, the research supports the view that cohesion is a subjective concept reflecting a cognitive combination of class features; as such it is a surrogate for class comprehension

The Use of Quantitative and Qualitative Analysis in the General Chemistry Laboratory

Author Institution: California Institute of Technology, Pasadena, Californi

Fourteen Years of Education and Public Outreach for the Swift Gamma-ray Burst Explorer Mission

The Sonoma State University (SSU) Education and Public Outreach (E/PO) group leads the Swift Education and Public Outreach program. For Swift, we have previously implemented broad efforts that have contributed to NASA's Science Mission Directorate E/PO portfolio across many outcome areas. Our current focus is on highly-leveraged and demonstrably successful activities, including the wide-reaching Astrophysics Educator Ambassador program, and our popular websites: Epo's Chronicles and the Gamma-ray Burst (GRB) Skymap. We also make major contributions working collaboratively through the Astrophysics Science Education and Public Outreach Forum (SEPOF) on activities such as the on-line educator professional development course NASA's Multiwavelength Universe. Past activities have included the development of many successful education units including the GEMS Invisible Universe guide, the Gamma-ray Burst Educator's guide, and the Newton's Laws Poster set; informal activities including support for the International Year of Astronomy, the development of a toolkit about supernovae for the amateur astronomers in the Night Sky Network, and the Swift paper instrument and glider models.Comment: 7th Huntsville Gamma-Ray Burst Symposium, GRB 2013: paper 42 in eConf Proceedings C130414

A Case of Alopecia Areata in an Opossum

On Dec. 30, 1949 a male opossum of undetermined age was presented at Stange Memorial Clinic, with a history of having lost its hair in irregular shaped patches

PEST CONTROL METHODS AND PEOPLE

Frankly I am not sure what Pest Control Methods and People really means. When I asked what I should cover, I was told to give a general discussion on pesticides. I am not sure this is appropriate even though the laws and regulations that pertain to other pesticides apply equally to those materials used in vertebrate pest control; the conditions of use, the types of chemicals used, their effect upon various animal species, and the number of chemicals available are so different from the pesticides used in controlling invertebrate pests that generalizations may not cover the topic. There are, however, a few basic principles that do pertain and I will discuss these. Mr. Cummings suggested that I cover the University\u27s policy in regards to the use of and recommendations for pesticides by our experiment station and Extension Service personnel and I will do this a little later. Looking back to your last conference in February of 1962 we find that a number of topics were discussed at that time which is being further elaborated upon during the present conference and some of these lend themselves to the discussion this morning. Dean Aldrich pointed out the importance of several bird and rodent species as enemies of our agriculture. Further, he brought out the point that many of these pests are the result of our intensified agricultural practices. When we plant certain crops over a wide area we change the environmental and ecological conditions and frequently bring about a situation that is conducive to large populations of organisms which, under the natural conditions that prevailed before the land was put into crop production, would not have occurred and, furthermore, these animals would not have been considered pests under ordinary population densities. Field mice in our orchards and sugar beet fields, gophers in alfalfa, starlings in feed lots and grapes are examples of vertebrates that fall into this category. Some imported species such as the starling have found conditions good. Others are native species which have adapted to these changed conditions. There are many such examples among insects. One striking case is that of the alfalfa butterfly. This insect is native to the United States. It lived upon various legumes and was considered a pretty but unimportant butterfly for many years