An Empirical Study of Cohesion and Coupling: Balancing Optimisation and Disruption

Search based software engineering has been extensively applied to the problem of finding improved modular structures that maximise cohesion and minimise coupling. However, there has, hitherto, been no longitudinal study of developers’ implementations, over a series of sequential releases. Moreover, results validating whether developers respect the fitness functions are scarce, and the potentially disruptive effect of search-based remodularisation is usually overlooked. We present an empirical study of 233 sequential releases of 10 different systems; the largest empirical study reported in the literature so far, and the first longitudinal study. Our results provide evidence that developers do, indeed, respect the fitness functions used to optimise cohesion/coupling (they are statistically significantly better than arbitrary choices with p << 0.01), yet they also leave considerable room for further improvement (cohesion/coupling can be improved by 25% on average). However, we also report that optimising the structure is highly disruptive (on average more than 57% of the structure must change), while our results reveal that developers tend to avoid such disruption. Therefore, we introduce and evaluate a multi-objective evolutionary approach that minimises disruption while maximising cohesion/coupling improvement. This allows developers to balance reticence to disrupt existing modular structure, against their competing need to improve cohesion and coupling. The multi-objective approach is able to find modular structures that improve the cohesion of developers’ implementations by 22.52%, while causing an acceptably low level of disruption (within that already tolerated by developers)

Consumer Willingness to Pay for Preservative-Free Food: The Case of Beijing

Consumers are facing a trade-off between the benefits of an increase in the length of the shelf life of food, such as low food costs, and the potential health damages caused by food preservatives. However, few studies in the current literature place emphasis on food preservatives, neither from a scientific perspective nor from an economic perspective. This causes a lot of controversies about government regulations. By constructing a theoretical framework and using a survey of 293 customers from 25 supermarkets in Beijing, this paper studies the consumer attitude towards food preservatives and attempts to fill the gap in the current literature. The main findings include that food price, and consumers' age and income are important for the willingness to pay (WTP) for 'preservative-free food' in Beijing. In particular, food price and consumer incomes are positively correlated with the WTP and there might be an inverted U-shaped relationship between age and WTP. This study indicates that consumers in Beijing are willing to pay a very high premium for preservative-free food 62% for preservative-free Mooncakes compared to conventional ones

A 3-dimensional coordination polymer with a rare lonsdaleite topology constructed from a tetrahedral ligand

A new 3D coordination polymer was solvothermally synthesized. The coordination polymer possesses a lon network built from 4-connecting Co-2 clusters and tetracarboxylate ligands, and exhibits selective gas sorption behavior as well as antiferromagnetic interactions.close131

Enzymatic treatments to improve mechanical properties and surface hydrophobicity of jute fiber membranes

Fiber membranes prepared from jute fragments can be valuable, low cost, and renewable. They have broad application prospects in packing bags, geotextiles, filters, and composite reinforcements. Traditionally, chemical adhesives have been used to improve the properties of jute fiber membranes. A series of new laccase, laccase/mediator systems, and multi-enzyme synergisms were attempted. After the laccase treatment of jute fragments, the mechanical properties and surface hydrophobicity of the produced fiber membranes increased because of the cross-coupling of lignins with ether bonds mediated by laccase. The optimum conditions were a buffer pH of 4.5 and an incubation temperature of 60 °C with 0.92 U/mL laccase for 3 h. Laccase/guaiacol and laccase/alkali lignin treatments resulted in remarkable increases in the mechanical properties; in contrast, the laccase/2,2-azino-bis-(3-ethylthiazoline-6-sulfonate) (ABTS) and laccase/2,6-dimethoxyphenol treatments led to a decrease. The laccase/ guaiacol system was favorable to the surface hydrophobicity of jute fiber membranes. However, the laccase/alkali lignin system had the opposite effect. Xylanase/laccase and cellulase/laccase combined treatments were able to enhance both the mechanical properties and the surface hydrophobicity of jute fiber membranes. Among these, cellulase/laccase treatment performed better; compared to mechanical properties, the surface hydrophobicity of the jute fiber membranes showed only a slight increase after the enzymatic multi-step processes.Financially supported by the National Natural Science Foundation of China (51173071, 21274055), Program for New Century Excellent Talents in University (NCET-12-0883), Program for Changjiang Scholars, Innovative Research Team in University (IRT _15R26), and Fundamental Research Funds for the Central Universities (JUSRP51312B, JUSRP51505

Pulmonary alveolar type I cell population consists of two distinct subtypes that differ in cell fate.

Pulmonary alveolar type I (AT1) cells cover more than 95% of alveolar surface and are essential for the air-blood barrier function of lungs. AT1 cells have been shown to retain developmental plasticity during alveolar regeneration. However, the development and heterogeneity of AT1 cells remain largely unknown. Here, we conducted a single-cell RNA-seq analysis to characterize postnatal AT1 cell development and identified insulin-like growth factor-binding protein 2 (Igfbp2) as a genetic marker specifically expressed in postnatal AT1 cells. The portion of AT1 cells expressing Igfbp2 increases during alveologenesis and in post pneumonectomy (PNX) newly formed alveoli. We found that the adult AT1 cell population contains both Hopx+Igfbp2+ and Hopx+Igfbp2- AT1 cells, which have distinct cell fates during alveolar regeneration. Using an Igfbp2-CreER mouse model, we demonstrate that Hopx+Igfbp2+ AT1 cells represent terminally differentiated AT1 cells that are not able to transdifferentiate into AT2 cells during post-PNX alveolar regeneration. Our study provides tools and insights that will guide future investigations into the molecular and cellular mechanism or mechanisms underlying AT1 cell fate during lung development and regeneration

A supramoleculear self-assembled flexible open framework based on the coordination of honeycomb layers possessing octahedral and tetrahedral Co-II geometries

A flexible open framework, {[Co2(L)Cl(DMF)2(H 2O)]??Sx}n (H3L = 4,4???,4??????-[1,3,5-benzenetriyltris(carbonylimino)]-trisbenzoic acid, DMF = dimethylformamide), was constructed based on a honeycomb coordination subunit with both octahedral and tetrahedral CoII sites, showing moderate MeOH sorption and antiferromagnetic properties.close0