One-off events? An empirical study of hackathon code creation and reuse.

Context: Hackathons have become popular events for teams to collaborate on projects and develop software prototypes. Most existing research focuses on activities during an event with limited attention to the evolution of the hackathon code. Objective: We aim to understand the evolution of code used in and created during hackathon events, with a particular focus on the code blobs, specifically, how frequently hackathon teams reuse pre-existing code, how much new code they develop, if that code gets reused afterwards, and what factors affect reuse. Method: We collected information about 22,183 hackathon projects from Devpost and obtained related code blobs, authors, project characteristics, original author, code creation time, language, and size information from World of Code. We tracked the reuse of code blobs by identifying all commits containing blobs created during hackathons and identifying all projects that contain those commits. We also conducted a series of surveys in order to gain a deeper understanding of hackathon code evolution that we sent out to hackathon participants whose code was reused, whose code was not reused, and developers who reused some hackathon code. Result: 9.14% of the code blobs in hackathon repositories and 8% of the lines of code (LOC) are created during hackathons and around a third of the hackathon code gets reused in other projects by both blob count and LOC. The number of associated technologies and the number of participants in hackathons increase reuse probability. Conclusion: The results of our study demonstrates hackathons are not always "one-off" events as the common knowledge dictates and it can serve as a starting point for further studies in this area.

Prescriptive process monitoring: Quo vadis?

Prescriptive process monitoring methods seek to optimize a business process by recommending interventions at runtime to prevent negative outcomes or address poorly performing cases. In recent years, various prescriptive process monitoring methods have been proposed. This article studies existing methods in this field via a systematic literature review (SLR). In order to structure the field, this article proposes a framework for characterizing prescriptive process monitoring methods according to their performance objective, performance metrics, intervention types, modeling techniques, data inputs, and intervention policies. The SLR provides insights into challenges and areas for future research that could enhance the usefulness and applicability of prescriptive process monitoring methods. This article highlights the need to validate existing and new methods in real-world settings, extend the types of interventions beyond those related to the temporal and cost perspectives, and design policies that take into account causality and second-order effects.

Influence of intramedullary nail diameter and locking mode on the stability of tibial shaft fracture fixation.

BACKGROUND: Fracture healing is affected by the type and the magnitude of movements at the fracture site. Mechanical conditions will be a function of the type of fracture management, the distance between the fracture fragments, and the loading of the fracture site. The hypothesis to be tested was that the use of a larger-diameter intramedullary nail, together with compressed interlocking, would enhance the primary stiffness and reduce fracture site movements, especially those engendered by shearing forces. MATERIALS AND METHODS: Six pairs of human tibiae were used to study the influence on fracture site stability of two different diameters (9 and 11 mm) of intramedullary nails, in tension/compression, torsional, four-point bending, and shear tests. The nails were used with two interlocking modes (static interlocking vs. dynamic compression). RESULTS: With static interlocking, the 11-mm-diameter nail provided significantly (30-59%) greater reduction of fracture site movement, as compared with the 9-mm-diameter nail. Using an 11-mm-diameter nail, the stiffness of the bone-implant construct was enhanced by between 20 and 50%. Dynamic compression allowed the interfragmentary movements at the fracture site to be further reduced by up to 79% and the system stiffness to be increased by up to 80%. CONCLUSION: On biomechanical grounds, the largest possible nail diameter should be used, with minimal reaming, so as to minimize fracture site movement. Compression after meticulous reduction should be considered in axially stable fractures.

Interfragmentary movement in diaphyseal tibia fractures fixed with locked intramedullary nails.

OBJECTIVES: Biomechanical study on cadaveric bones using physiological loading conditions to quantify interfragmentary movements in a tibial shaft fracture model fixed by intramedullary nailing. METHODS: Six fresh frozen human cadaveric tibiae were sequentially tested in axial, torsional, 4-point bending, and shear loading configurations. Tests were performed in intact specimens and osteotomized specimens equipped with interlocked intramedullary nails. The amount of clearance of the nail within the intramedullary canal was measured on computed tomography scans. Linear and angular deformations of the fragments were continuously measured in all directions to obtain the exact interfragmentary movements. RESULTS: The amount of movement at the site of the fracture was substantial. Especially shear and torsion resulted in gap movements of up to 10 mm. Movements in the transverse plane were significantly larger than axial movements for all loading conditions. For torsion and bending, a significant portion of the movement of the fracture gap resulted from the flexibility of the intramedullary nail; for compression and shear, the majority of the movement was related to the clearance of the nail within the bone. CONCLUSIONS: Clearance of the implant within the medullary canal, the flexibility of the implant itself, and the compliance of the implant (nail and locking screws) within the bone determine the extent of movement. The implant flexibility and the clearance are strongly dependent on the thickness of the intramedullary nail.