Requirements engineering in software product line engineering

Many attempts have been made to increase the productivity and quality of software products based on software reuse. Software product line practice is one such approach, one that focuses on developing a family of products which have a majority of features in common. Hence, there are numerous requirements that are common across the family, but others are unique to individual products. Traditional requirements engineering methods were conceived to deal with single product requirements and are usually not flexible enough to address the needs arising from reusing requirements for a family of products. There is also the additional burden of correctly identifying and engineering both product-line-wide requirements and product-specific requirements as well as evolving them. Therefore, in this special issue, we want to highlight the importance and the role of requirements engineering for product line development as well as to provide insights into the state of the art in the field.     

Bioactive compounds,in vitro antioxidant capacity and Maillard reaction products of raw,boiled and fried garlic (Allium sativum L.)

Garlic is used in many dishes but some of its bioactive compounds are lost when exposed to heat. This study evaluated bioactive compounds, antioxidant activity and Maillard reaction products of raw (RG), boiled (BG) and fried garlic (FG). Total phenolic compounds, flavonoids, allicin and phytosterol were quantified as well as dietary fibres and mineral content. Antioxidant activities of RG, BG and FG were evaluated by oxygen radical absorbance capacity (ORAC), oxidation of β‐carotene/linoleic acid and Rancimat methods. The main results were the following: thermal processing of RG decreased both bioactive compounds and antioxidant capacity, boiling was found to be less aggressive than frying, and strong correlations were obtained between total phenolic compounds and the antioxidant assays. However, phytosterol content was higher in FG than in RG and BG and higher temperatures increased the formation of Maillard reaction products. It was concluded that RG and BG should be preferred for human consumption as they present higher antioxidant capacity.     

Using Proteomics to Understand How Leishmania Parasites Survive inside the Host and Establish Infection

Leishmania is a protozoan parasite that causes a wide range of different clinical manifestations in mammalian hosts. It is a major public health risk on different continents and represents one of the most important neglected diseases. Due to the high toxicity of the drugs currently used, and in the light of increasing drug resistance, there is a critical need to develop new drugs and vaccines to control Leishmania infection. Over the past few years, proteomics has become an important tool to understand the underlying biology of Leishmania parasites and host interaction. The large-scale study of proteins, both in parasites and within the host in response to infection, can accelerate the discovery of new therapeutic targets. By studying the proteomes of host cells and tissues infected with Leishmania, as well as changes in protein profiles among promastigotes and amastigotes, scientists hope to better understand the biology involved in the parasite survival and the host-parasite interaction. This review demonstrates the feasibility of proteomics as an approach to identify new proteins involved in Leishmania differentiation and intracellular survival.     

Purification and characterization of a kinin-releasing and fibrinogen-clotting serine proteinase (KN-BJ) from the venom of Bothrops jararaca, and molecular cloning and sequence analysis of its cDNA

Two forms of a proteinase, KN-BJ 1 and 2, were purified to homogeneity from the venom of Bothrops jararaca. In SDS/PAGE reduced KN-BJ 1 and 2 migrated as single bands with molecular masses of 38 kDa and 39 kDa. The two enzymes have similar N-terminal amino acid sequences and specific activities on synthetic chromogenic substrates, and both release bradykinin from bovine low-molecular-mass kininogen. KN-BJ 1 and KN-BJ 2 clot fibrinogen with specific activities of 245 NIH U/mg and 219 NIH U/mg, releasing only fibrinopeptide A. The amidolytic, kinin-releasing and coagulant activities are inhibited by phenylmethylsulfonyl fluoride, demonstrating that KN-BJ is a serine proteinase. Benzamidine derivatives, which are competitive inhibitors of trypsin-like proteinases, also inhibited the amidolytic activity of KN-BJ. A cDNA clone (HS104, 2.2 kb) has been isolated from a cDNA library of B. jararaca venom glands with an ORF of 771 bp. The deduced amino acid sequence contains segments that are identical to the sequences of the N-terminus and three tryptic peptides of KN-BJ 2. Therefore, the cDNA is believed to represent the gene of KN-BJ 2. The deduced amino acid sequence indicates that KN-BJ 2 is synthesized as a prezymogen of 257 amino acids with a putative signal peptide of 18 amino acids and an activating peptide of six amino acid residues. The sequence of 233 amino acids representing the mature enzyme exhibits high similarity to sequences of serine proteinases isolated from crotalid venoms.     

An algebraic approach to the design of compilers for object-oriented languages

In this paper we describe an algebraic approach to construct provably correct compilers for object-oriented languages; this is illustrated for programs written in a language similar to a sequential subset of Java. It includes recursive classes, inheritance, dynamic binding, recursion, type casts and test, assignment, and class-based visibility, but a copy semantics. In our approach, we tackle the problem of compiler correctness by reducing the task of compilation to that of program refinement. Compilation is identified with the reduction of a source program to a normal form that models the execution of object code. The normal form is generated by a series of correctness-preserving transformations that are proved sound from the basic laws of the language; therefore it is correct by construction. The main advantages of our approach are the characterisation of compilation within a uniform framework, where comparisons and translations between semantics are avoided, and the modularity and extensibility of the resulting compiler.     

On the Grundy and b-Chromatic Numbers of a Graph

The Grundy number of a graph G, denoted by Γ(G), is the largest k such that G has a greedy k-colouring, that is a colouring with k colours obtained by applying the greedy algorithm according to some ordering of the vertexes of G. The b-chromatic number of a graph G, denoted by χ _b (G), is the largest k such that G has a b-colouring with k colours, that is a colouring in which each colour class contains a b-vertex, a vertex with neighbours in all other colour classes. Trivially χ _b (G),Γ(G)≤Δ(G)+1. In this paper, we show that deciding if Γ(G)≤Δ(G) is NP-complete even for a bipartite graph G. We then show that deciding if Γ(G)≥|V(G)|?k or if χ _b (G)≥|V(G)|?k are fixed parameter tractable problems with respect to the parameter k.     

Biological nitrogen fixation in tropical dry forests with different legume diversity and abundance

Tropical dry forests have high diversity and plant abundance of potentially biologically nitrogen fixing (BNF) legume species, attributed to the ecological advantage of fixation. However, there are few estimates of N quantities annually fixed, hindering the understanding of factors that control BNF, like low phosphorus availability. The quantities of N fixed in three dry forest (caatinga) fragments of the semiarid Brazilian northeastern region with different legume plant proportions were determined and seedlings of Mimosa tenuiflora were grown with phosphorous fertilized soil from the fragments to verify if lack of fixation was due to the absence of rhizobia populations or P deficiency. The vegetation of all areas was dominated by legume plants, mainly potentially nodulating ones, despite the relatively high soil N availability. M. tenuiflora was the most abundant nodulating legume in all fragments, with annual leaf productions from 800 to 1400 kg ha^?1. BNF amounts were low (1.4, 18 and 3.6 kg ha^?1 year^?1 in the mature caatinga of Petrolina and in the mature and regenerating caatingas of São João, respectively) considering the high proportions of potentially nodulating plants (33, 61 and 82% of total plant basal area), because 80, 10 and 70% of these plants were not fixing and those fixing had only 20–46% of their N derived from the atmosphere. Since the pot grown seedlings nodulated abundantly, the low BNF could not be explained by absence of microsymbionts but likely to low symbiosis efficiency due to relatively high N and low P availability.     

Accumulation and apparent recovery of N,P and K after the incorporation of gliricidia and manure in intercropping during the cultivation of corn–cowpea–cotton

Fertilization with manure is widely adopted by farmers in the semiarid region of northeastern Brazil, although the quantity of available manure is limited. Thus, among other alternatives, gliricidia has been used as an additional source of organic fertilizer. The objective of this study was to evaluate the accumulation and apparent recovery of N, P and K after using different forms of gliricidia and manure application in the intercropping of corn, cowpea and cotton in three crop cycles in the semi-arid northeast region of Brazil. The following treatments were used: gliricidia incorporated into the soil before planting; gliricidia spread on the surface of the soil at 45 days after planting; manure and gliricidia incorporated into the soil before planting; manure incorporated into the soil before planting and gliricidia spread on the surface of the soil at 45 days after planting; manure incorporated into the soil before planting; and no addition of organic fertilizer (control). Accumulations followed the same pattern as biomass production but differed greatly from the concentrations. Low apparent recoveries were obtained in the first and second cycles, and high apparent recoveries were obtained in the third cycle. The nutrient balances indicated that the incorporation of gliricidia before planting or spread on the surface does not meet crop needs. The incorporation of manure as well as manure and gliricidia when applied on the surface, were able to meet growth needs and maintain soil fertility.