The effects of change decomposition on code review -- a controlled experiment

Background: Code review is a cognitively demanding and time-consuming process. Previous qualitative studies hinted at how decomposing change sets into multiple yet internally coherent ones would improve the reviewing process. So far, literature provided no quantitative analysis of this hypothesis. Aims: (1) Quantitatively measure the effects of change decomposition on the outcome of code review (in terms of number of found defects, wrongly reported issues, suggested improvements, time, and understanding); (2) Qualitatively analyze how subjects approach the review and navigate the code, building knowledge and addressing existing issues, in large vs. decomposed changes. Method: Controlled experiment using the pull-based development model involving 28 software developers among professionals and graduate students. Results: Change decomposition leads to fewer wrongly reported issues, influences how subjects approach and conduct the review activity (by increasing context-seeking), yet impacts neither understanding the change rationale nor the number of found defects. Conclusions: Change decomposition reduces the noise for subsequent data analyses but also significantly supports the tasks of the developers in charge of reviewing the changes. As such, commits belonging to different concepts should be separated, adopting this as a best practice in software engineering

A Security Perspective on Code Review: The Case of Chromium

Modern Code Review (MCR) is an established software development process that aims to improve software quality. Although evidence showed that higher levels of review coverage relates to less post-release bugs, it remains unknown the effectiveness of MCR at specifically finding security issues. We present a work we conduct aiming to fill that gap by exploring the MCR process in the Chromium open source project. We manually analyzed large sets of registered (114 cases) and missed (71 cases) security issues by backtracking in the project's issue, review, and code histories. This enabled us to qualify MCR in Chromium from the security perspective from several angles: Are security issues being discussed frequently? What categories of security issues are often missed or found? What characteristics of code reviews appear relevant to the discovery rate? Within the cases we analyzed, MCR in Chromium addresses security issues at a rate of 1% of reviewers' comments. Chromium code reviews mostly tend to miss language-specific issues (e.g., C++ issues and buffer overflows) and domain-specific ones (such as Cross-Site Scripting), when code reviews address issues, mostly they address those that pertain to the latter type. Initial evidence points to reviews conducted by more than 2 reviewers being more successful at finding security issues

Immediate or delayed retrieval of the displaced third molar : A review

The displacement of a third molar is a rare occurrence, but it could lead to serious and/or life threatening complication. Aim of this review is to understand the most correlated causes of displacement and the possible solutions proposed in literature to avoid and solve this complication for maxillary and mandibular third molars at the appropriate time. A search for ?third molar displacement? was performed by using Pubmed database. Articles referred to soft tissues displacement, from 1957 to 2018, were included in the review. The references lists of all eligible articles were examined and additional studies were added to the review only if indexed on Pubmed. All the articles on maxillary sinus displacement and the dislocation of dental fragments or surgical equipment were excluded. From a total of 134 results, 68 articles were examined for satisfying inclusion criteria. 18 articles were excluded because not inherent with the topic; 19 articles on infratemporal space, 11 on sublingual space, 9 on submandibular space, 11 on lateral pharyngeal space displacement were considered congruent for the review and included. The displacement of the third molar in deeper tissues could be avoided by the use of proper surgical procedures and instrumentarium. If displacement occurs, and the operator could not reach the tooth in safe conditions, the patient should be immediately referred to a maxillo-facial surgeon, because of the possibility of further displacement or the onset of hazardous or potentially fatal infections in vital regions

Postextractive alveolar ridge preservation using L-PRF: clinical and histological evaluation

Leukocyte- and platelet-rich fibrin (L-PRF) is an autologous platelet concentrate rich in growth factors and plasma proteins, obtained by centrifugation of patient whole blood, and widely used in oral surgery. This report describes a case of alveolar ridge preservation with L-PRF membranes. Postextractive alveolar healing was then assessed through a histologic and histomorphometric analysis. A patient requiring tooth extraction and subsequent implant rehabilitation was treated with simple extraction and socket filling with L-PRF membranes. Implant placement was performed at 3 months, and a bone biopsy was obtained for histomorphometric analysis. Histological examination of the grafted sites showed that the use of L-PRF could achieve good results in terms of bone dimension and quality and soft tissue healing. The results of this study support the use of L-PRF membranes to preserve hard and soft tissues after tooth extraction

Electrocardiographic features, mapping and ablation of idiopathic outflow tract ventricular arrhythmias

Idiopathic outflow tract ventricular arrhythmias are ventricular tachycardias or premature ventricular contractions presumably not related to myocardial scar or disorders of ion channels. These arrhythmias have focal origin and display characteristic electrocardiographic features. The purpose of this article is to review the state of the art of diagnosis and treatment of idiopathic outflow tract ventricular arrhythmias

"Paradoxical" p16 overexpression in cutaneous melanoma: Molecular and immunohistochemical analysis of a rare phenomenon with a focus on cell cycle regulatory molecules

Background: One of the most relevant genetic alterations in cutaneous melanoma (CM) is the biallelic inactivation/loss-of-heterozygosis (LOH) of cyclin-dependent kinase inhibitor 2 A (CDKN2A), which results in the immunohistochemical loss of p16 frequently found in CM. However, we recently described a rare case of dermal/deep-seated melanoma arising in giant congenital nevus (DDM-GCN) with p16 overexpression combined with p53 loss and tumor protein 53 (TP53) mutation. Herein, we reported a case series of CM with p16 overexpression and analyzed their clinicopathologic features, immunohistochemical expression of the cell cycle regulatory molecules (CCRM: p53, p21, Cyclin D1, Rb), and mutational landscape. Methods: We retrospectively tested for p16 all cases of CM diagnosed at our institution between January 1st 2019-April 1st 2022. In CM with p16 overexpression, we reported clinicopathologic features, immunohistochemical results for melanocytic markers and CCRM, and mutational landscape investigated with a next-generation sequencing (NGS) panel. In cases with zonal p16 overexpression, the immunohistochemical assessment for melanocytic markers and CCRM, as well as the NGS analysis have been performed in both components {with and without p16 overexpression [p16(+)c and p16(-)]}. Results: Overexpression of p16 was found in 10/2879 (0.35%) CM [5/10 (50%) diffuse and 5/10 (50%) zonal]. We combined the immunohistochemical results for CCRM and molecular data to classify the cases as follows: a) Group 1 with altered expression of at least one CCRM but no TP53 mutations [3/10 (30%), all with Rb altered/lost]; b) Group 2 with altered expression of at least one CCRM and TP53 mutations [4/10 (40%), all with p53 altered]; c) Group 3 with normal expression of CCRM and no TP53 mutations [3/10 (30%), all with mutations in MAPK pathway genes (NRAS and BRAF)]. In CM with zonal p16 overexpression, the histologic appearance of p16(+)c was heterogeneous, whereas combining CCRM profiles and molecular data the cases could be categorized as follows: a) cases with the same CCRM and molecular profiles in both p16(+)c and p16(-)c; b) cases with p16(+)c showing additional genetic mutations and/or modifications of CCRM expression. Conclusions: p16 overexpression is a rare event, occurring in advanced-stage, clinically- and histologically-heterogeneous CM. These lesions may be classified into three different groups based on CCRM expression and mutational profiles (including TP53 mutation). The analysis of CM with zonal p16 overexpression suggests that, at least in a subset of cases, this phenomenon could represent a sign of "molecular progression" due to the acquisition of additional genetic mutations and/or modifications of the CCRM profile

The thick-bedded tail of turbidite thickness distribution as a proxy for flow confinement: examples from Tertiary basins of central and northern Apennines (Italy)

This study reviews the thickness statistics of non-channelized turbidites from four tertiary basins of Central-Northern Apennines (Italy), where bed geometry and sedimentary character have been previously assessed. Though very different in terms of size and, arguably, character of feeder system, these basins share a common stratigraphic evolution consisting in transition from an early ponded to a late unconfined setting of deposition. Based on comparison of thickness subsets from diverse locations and stratigraphic heights within the studied turbidite fills, this paper seeks to answer the following questions: i) how data collection procedures and field operational constraints (e.g. measure location, outcrop quality, use of thicknesses data from single vs. multiple correlative sections, stratigraphic thickness of the study interval) can affect statistics of sample data? ii) how depositional controls of confined vs. unconfined turbidite basins can result in different thickness-frequency distributions?; and iii) is there in thickness statistics a ‘flow confinement’ signature which can be used to distinguish between confined and unconfined turbidites? Results suggest that: i) best practices of data collection are crucial to a meaningful interpretation of sample data statistics, especially in presence of stratigraphic and spatial trends of turbidite bed thickness; ii) a systematic bias against cm-thick Tcd Bouma sequence turbidites exists in sample data, which can result in the low-end tail of empirical thickness-frequency distributions to depart significantly from the actual distribution of turbidite thickness; and iii) thickness statistics of beds starting with a basal Ta/Tb Bouma division bear a coherent relationship to the transition from ponded to unconfined depositional settings, consisting in reduction of variance and mean and, consequently, parameters, or even type, of best fit model distribution. This research highlights the role of flow stripping, sediment by-pass and bed geometry in altering the initial thickness distribution of ponded turbidites and suggests how fully ponded mini-basins represent the ideal setting for further research linking turbidite thickness statistics and frequency distribution of parent flow volumes