Why Modern Open Source Projects Fail

Open source is experiencing a renaissance period, due to the appearance of modern platforms and workflows for developing and maintaining public code. As a result, developers are creating open source software at speeds never seen before. Consequently, these projects are also facing unprecedented mortality rates. To better understand the reasons for the failure of modern open source projects, this paper describes the results of a survey with the maintainers of 104 popular GitHub systems that have been deprecated. We provide a set of nine reasons for the failure of these open source projects. We also show that some maintenance practices -- specifically the adoption of contributing guidelines and continuous integration -- have an important association with a project failure or success. Finally, we discuss and reveal the principal strategies developers have tried to overcome the failure of the studied projects.Comment: Paper accepted at 25th International Symposium on the Foundations of Software Engineering (FSE), pages 1-11, 201

a comparison of morphological and petrological methods

In planetary sciences, the emplacement of lava flows is commonly modelled using a single rheological parameter (apparent viscosity or apparent yield strength) calculated from morphological dimensions using Jeffreysʼ and Hulmeʼs equations. The rheological parameter is then typically further interpreted in terms of the nature and chemical composition of the lava (e.g., mafic or felsic). Without the possibility of direct sampling of the erupted material, the validity of this approach has remained largely untested. In modern volcanology, the complex rheological behaviour of lavas is measured and modelled as a function of chemical composition of the liquid phase, fractions of crystals and bubbles, temperature and strain rate. Here, we test the planetary approach using a terrestrial basaltic lava flow from the Western Volcanic Zone in Iceland. The geometric parameters required to employ Jeffreysʼ and Hulmeʼs equations are accurately estimated from high-resolution HRSC-AX Digital Elevation Models. Samples collected along the lava flow are used to constrain a detailed model of the transient rheology as a function of cooling, crystallisation, and compositional evolution of the residual melt during emplacement. We observe that the viscosity derived from the morphology corresponds to the value estimated when significant crystallisation inhibits viscous deformation, causing the flow to halt. As a consequence, the inferred viscosity is highly dependent on the details of the crystallisation sequence and crystal shapes, and as such, is neither uniquely nor simply related to the bulk chemical composition of the erupted material. This conclusion, drawn for a mafic lava flow where crystallisation is the primary process responsible for the increase of the viscosity during emplacement, should apply to most of martian, lunar, or mercurian volcanic landforms, which are dominated by basaltic compositions. However, it may not apply to felsic lavas where vitrification resulting from degassing and cooling may ultimately cause lava flows to halt

Impact interaction of in-flight high-energy molten volcanic ash droplets with jet engines

© 2019 The turbine technology incorporated in jet engines is inherently vulnerable to attack by environmental silicate debris. Amongst the various kinds of such debris, volcanic ash is a particular threat as its glass softens to a liquid at temperatures of 500–800 °C, far below jet engine operating temperatures of ∼1500 °C. As a result, ingested re-molten droplets impact and form splats on the protective thermal barrier coatings (TBCs). Investigation of the damage to jet engines ensuing from this process has, to date been restricted to forensic observations after critical encounters. Here, we employ a thermal spray technology to recreate the ‘in-situ’ generation of molten volcanic ash droplets and observe their morphological evolution and interaction with TBCs. The mechanism of splat formation is found to depend both on substrate topography and on in-flight droplet characteristics, whereby splat circularity increases with surface roughness and with the product of the Weber and Reynolds numbers. The experiments reveal that the molten ash droplet adhesion rate is dictated by droplet temperature and viscosity, ash concentration and substrate roughness. A new dimensionless number, S, is developed to quantify the molten ash droplet adhesion rate to both substrate topography and in-flight droplet characteristics. These findings provide a greatly improved basis for the quantification of the hazard potential of volcanic ash to jet engines and should be incorporated into protocols for operational aviation response during volcanic crises

Incidence of gallbladder lithiasis after ceftriaxone treatment

Ceftriaxone has potent activity against a broad range of Gram-positive and Gram-negative bacteria. While it is eliminated mainly by the kidney, 10-20% of the drug is eliminated in the bile and ceftriaxone salt precipitates have been described in the gallbladder of animals dosed with ceftriaxone. The purpose of the present study was to investigate the incidence of biliary lithiasis 6 and 12 months after treatment with ceftriaxone and to compare it with that in patients treated with amoxycillin/clavulanate. Biliary ultrasonography was performed at the start of treatment, at 6 months and at 12 months after the beginning of the study. One hundred patients were randomized and 74 were evaluable: 34 were given amoxycillin/clavulanate, 40 ceftriaxone. Gallbladder lithiasis developed in one patient 12 months after the amoxycillin/clavulanate treatment and in none in the ceftriaxone treatment arm. Biliary precipitate during ceftriaxone treatment was not looked for because this phenomenon was not known at the beginning of the study, but gallbladder precipitation that was seen in two patients given ceftriaxone during and at the end of treatment, respectively, resolved spontaneously. In conclusion, ceftriaxone treatment does not appear to lead to gallstone formation more often than an antibiotic that is not eliminated through the bil

What promotes or prevents greater use of appropriate compression in people with venous leg ulcers? A qualitative interview study with nurses in the north of England using the Theoretical Domains Framework

OBJECTIVES: To investigate factors that promote and prevent the use of compression therapy in people with venous leg ulcers. DESIGN: Qualitative interview study with nurses using the Theoretical Domains Framework (TDF). SETTING: Three National Health Service Trusts in England. PARTICIPANTS: Purposive sample of 15 nurses delivering wound care. RESULTS: Nurses described factors which made provision of compression therapy challenging. Organisational barriers (TDF domains environmental context and resources/knowledge, skills/behavioural regulation) included heavy/increasing caseloads; lack of knowledge/skills and the provision of training; and prescribing issues (variations in bandaging systems/whether nurses could prescribe). Absence of specialist leg ulcer services to refer patients into was perceived as a barrier to providing optimal care by some community-based nurses. Compression use was perceived to be facilitated by clinics for timely initial assessment; continuity of staff and good liaison between vascular/leg ulcer clinics and community teams; clear local policies and care pathways; and opportunities for training such as ‘shadowing’ in vascular/leg ulcer clinics. Patient engagement barriers (TDF domains goals/beliefs about consequences) focused on getting patients ‘on board’ with compression, and supporting them in using it. Clear explanations were seen as key in promoting compression use. CONCLUSIONS: Rising workload pressures present significant challenges to enhancing leg ulcer services. There may be opportunities to develop facilitated approaches to enable community nursing teams to make changes to practice, enhancing quality of patient care. The majority of venous leg ulcers could be managed in the community without referral to specialist community services if issues relating to workloads/skills/training are addressed. Barriers to promoting compression use could also be targeted, for example, through the development of clear patient information leaflets. While the patient engagement barriers may be easier/quicker to address than organisational barriers, unless organisational barriers are addressed it seems unlikely that all people who would benefit from compression therapy will receive it

One-Year Risk of Stroke after Transient Ischemic Attack or Minor Stroke

BACKGROUND Previous studies conducted between 1997 and 2003 estimated that the risk of stroke or an acute coronary syndrome was 12 to 20% during the first 3 months after a transient ischemic attack (TIA) or minor stroke. The TIAregistry.org project was designed to describe the contemporary profile, etiologic factors, and outcomes in patients with a TIA or minor ischemic stroke who receive care in health systems that now offer urgent evaluation by stroke specialists. METHODS We recruited patients who had had a TIA or minor stroke within the previous 7 days. Sites were selected if they had systems dedicated to urgent evaluation of patients with TIA. We estimated the 1-year risk of stroke and of the composite outcome of stroke, an acute coronary syndrome, or death from cardiovascular causes. We also examined the association of the ABCD2 score for the risk of stroke (range, 0 [lowest risk] to 7 [highest risk]), findings on brain imaging, and cause of TIA or minor stroke with the risk of recurrent stroke over a period of 1 year. RESULTS From 2009 through 2011, we enrolled 4789 patients at 61 sites in 21 countries. A total of 78.4% of the patients were evaluated by stroke specialists within 24 hours after symptom onset. A total of 33.4% of the patients had an acute brain infarction, 23.2% had at least one extracranial or intracranial stenosis of 50% or more, and 10.4% had atrial fibrillation. The Kaplan–Meier estimate of the 1-year event rate of the composite cardiovascular outcome was 6.2% (95% confidence interval, 5.5 to 7.0). Kaplan–Meier estimates of the stroke rate at days 2, 7, 30, 90, and 365 were 1.5%, 2.1%, 2.8%, 3.7%, and 5.1%, respectively. In multivariable analyses, multiple infarctions on brain imaging, large-artery atherosclerosis, and an ABCD2 score of 6 or 7 were each associated with more than a doubling of the risk of stroke. CONCLUSIONS We observed a lower risk of cardiovascular events after TIA than previously reported. The ABCD2 score, findings on brain imaging, and status with respect to large-artery atherosclerosis helped stratify the risk of recurrent stroke within 1 year after a TIA or minor stroke. (Funded by Sanofi and Bristol-Myers Squibb.)Supported by an unrestricted grant from Sanofi and Bristol-Myers Squibb