An empirical study of the impact of modern code review practices on software quality

Software code review, i.e., the practice of having other team members critique changes to a software system, is a well-established best practice in both open source and proprietary software domains. Prior work has shown that formal code inspections tend to improve the quality of delivered software. However, the formal code inspection process mandates strict review criteria (e.g., in-person meetings and reviewer checklists) to ensure a base level of review quality, while the modern, lightweight code reviewing process does not. Although recent work explores the modern code review process, little is known about the relationship between modern code review practices and long-term software quality. Hence, in this paper, we study the relationship between post-release defects (a popular proxy for long-term software quality) and: (1) code review coverage, i.e., the proportion of changes that have been code reviewed, (2) code review participation, i.e., the degree of reviewer involvement in the code review process, and (3) code reviewer expertise, i.e., the level of domain-specific expertise of the code reviewers. Through a case study of the Qt, VTK, and ITK projects, we find that code review coverage, participation, and expertise share a significant link with software quality. Hence, our results empirically confirm the intuition that poorly-reviewed code has a negative impact on software quality in large systems using modern reviewing tools.     

Microfluidic‐Nanofiber Hybrid Array for Screening of Cellular Microenvironments

Cellular microenvironments are generally sophisticated, but crucial for regulating the functions of human pluripotent stem cells (hPSCs). Despite tremendous effort in this field, the correlation between the environmental factors—especially the extracellular matrix and soluble cell factors—and the desired cellular functions remains largely unknown because of the lack of appropriate tools to recapitulate in vivo conditions and/or simultaneously evaluate the interplay of different environment factors. Here, a combinatorial platform is developed with integrated microfluidic channels and nanofibers, associated with a method of high‐content single‐cell analysis, to study the effects of environmental factors on stem cell phenotype. Particular attention is paid to the dependence of hPSC short‐term self‐renewal on the density and composition of extracellular matrices and initial cell seeding densities. Thus, this combinatorial approach provides insights into the underlying chemical and physical mechanisms that govern stem cell fate decisions.     

Effects of chlorine on the decrease of estrogenic chemicals

The effects of chlorination on the elimination of three estrogenic chemicals such as 17beta-estradiol, nonylphenol and bis-phenol A were investigated using yeast two-hybrid assay (YTA), estrogen receptor (ER) competition assay (ER-CA), and high-performance liquid chromatography/mass spectrometry (LC/MS). The results of YTA, ER-CA and the analysis of LC/MS indicated that the estrogenic activity of the above-mentioned three endocrine disruptors were significantly reduced as a result of chlorination. The decrease in estrogenic activity paralleled a decrease in estrogenic chemicals under the influence of free chlorine. One common characteristic of estrogenic chemicals is the presence of a phenolic ring. Considering that a phenolic ring is likely to undergo some sort of transformation in an aqueous chlorination solution, the above-mentioned results may be applied to the rest of the estrogenic chemicals in natural waters.     

Removal efficiency and homologue patterns of dioxins in drinking water treatment

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (Co-PCBs) analyses in raw and treated water throughout Japan were implemented to identify the concentration and homologue patterns of dioxins before and after the water treatment process. In 40 surface water and 5 ground water treatment plants, the removal efficiency of dioxins and the influence of extent chlorination on dioxins increase in drinking water were also studied. Raw water and treated water were sampled twice, summer and winter. The mean concentration in raw water and treated water of dioxins was 56.45 pg/L (0.15 pg WHO-TEQ/L) and 4.24 pg/L (0.019 pg WHO-TEQ/L), respectively. Location of water treatment plants not only significantly influenced the concentration level of dioxins but also resulted in different homologue patterns of dioxins. Levels of dioxins in ground water were much less than that of surface water in both raw and treated water. This study shows most dioxin congeners are well removed (87% removal efficiency) by water treatment. However, in some water treatment plants, the level of TeCDFs (pg WHO-TEQ/L) increased as a result of chlorination.     

Laser‐addressed full‐color photo‐quality rewritable sheets based on thermochromic systems with leuco dyes

We have developed a laser‐addressed full‐color photographic quality rewritable sheet. The sheet was composed of a vertically stacked Cyan/Magenta/Yellow‐thermochromic system with a mixture of leuco dyes, developers and photothermal conversion agents in a polymer matrix. The sheet was simply manufactured by roll‐to‐roll (R2R) processes. Writing and erasing were performed by scan of near‐infrared laser light. It achieved full‐color photographic quality images with a wide color gamut with 70% coverage of the Specifications for Web Offset Publications (SWOP) standards and a high resolution of 426 ppi. Clear rewritability has also been confirmed. Non‐contact laser writing has other advantages in that it can create an image under a protection film, and it has form factor flexibility. We have developed a reliability model for high‐temperature storage and a light fastness test. This model showed a good agreement with experimental data, and the lifetime of an image was estimated to be over 8 years under ambient conditions. This technology will create applications for on‐demand rewritable image design while saving power and reducing the use of paper, which will eventually contribute to a sustainable society.     

Serum autoantibody to sideroflexin 3 as a novel tumor marker for oral squamous cell carcinoma

The purpose of this study is to establish a tumor marker that can be applied for the early detection and follow-up of oral cancer patients. Employing the proteomic approach using MALDI TOF-MS, 2-DE, patient's sera and culturing cell lines, the serum autoantibodies (autoAbs) were screened and the serum levels were estimated by ELISA. Targeting the tumor cell invasion into the surrounding stromal tissues, MRC-5 human fibroblasts were employed as the target cells and a mitochondrial membrane protein, sideroflexin 3 (SFXN3), was identified. The serum anti-SFXN3-autoAb levels elevated in patients with the oral squamous cell carcinoma significantly: with 77% sensitivity and 89% specificity against control samples. The serum anti-SFXN3-autoAb levels were mildly correlated with the primary tumor sizes, however, the levels were slightly highly elevated in T1 early cancer. An immunohistochemical analysis revealed that the SFXN3 protein is expressed in the stromal fibroblasts between the caner nests and also in the basal layer of the squamous epithelium. Changes in the serum anti-SFXN3-autoAb levels after therapy correlated with the clinical tumor burden. These findings demonstrated that the serum anti-SFXN3-autoAb is worthy of clinical evaluation as a potentially of the novel tumor maker for the early detection of oral squamous cell carcinoma.     

Active adaptation in human-agent collaborative interaction

When a human user interacts with an adaptive agent to achieve human-agent collaboration, active adaptation is considered to be one of the critical characteristics of the agent. In order to investigate the principal features of active adaptation, we developed a human-agent collaborative experimental environment called WAITER (waiter agent interactive training experimental restaurant) and conducted two types of experiments, a Wizard of OZ (WOZ) agent experiment and an autonomous agent experiment. The objective of these experiments is to observe how human users perceive the agents and change their instructions when interacting with adaptive agents. The results indicate that humans can recognize changes in the agent’s actions and change their instruction methods accordingly. This implies that active adaptation of the agents may encourage the adaptation of the human users and help to build an adaptation loop between them. The experimental results also suggest that active adaptation may play an important role in a human-agent collaborative task.     

Arsenic contamination of groundwater in Nawabganj, Bangladesh, focusing on the relationship with other metals and ions.

Serious arsenic contamination of groundwater in Bangladesh has been frequently reported and is of great concern. In this research, repeated water sampling from the same 10 tubewells in Nawabganj municipality, Bangladesh, was conducted and analysed, focusing on the seasonal variation of water quality and the relationship among arsenic and other metals and ions. For the seasonal variation of water quality, arsenic and iron concentrations were higher in the rainy season in general although the tendency was not consistent and it depended on the tubewell and the time. Correlation between arsenic and iron could not be observed in this study (r = -0.01) when using all cases. This was because no correlation was observed in the higher arsenic concentration range. Arsenic removal by co-precipitation with coexisting iron is known as one of the locally applicable techniques in Bangladesh, but the result from this study suggests that some additional treatments such as the extra injection of iron should be performed in some cases, especially where the arsenic concentration is high. The correlation between arsenic and other substances was also analysed. As a result, manganese (r = 0.37), molybdenum (r = 0.33) and sulfate ion (r = -0.33) significantly correlated with arsenic (p < 0.05). The negative correlation between arsenic and sulfate ion implies the dissolution of arsenic into groundwater under reductive conditions although there are some exceptional cases.