Coordination Implications of Software Coupling in Open Source Projects

The effect of software coupling on the quality of software has been studied quite widely since the seminal paper on software modularity by Parnas [1]. However, the effect of the increase in software coupling on the coordination of the developers has not been researched as much. In commercial software development environments there normally are coordination mechanisms in place to manage the coordination requirements due to software dependencies. But, in the case of Open Source software such coordination mechanisms are harder to implement, as the developers tend to rely solely on electronic means of communication. Hence, an understanding of the changing coordination requirements is essential to the management of an Open Source project. In this paper we study the effect of changes in software coupling on the coordination requirements in a case study of a popular Open Source project called JBoss

Pyrite oxidation and the associated geochemical processes in tailings in the Atacama desert / Chile: the influence of man controlled water input after disuse

This paper reports the results of a study of two tailings, under desert conditions in the III. Region of Chile. Both tailings received significant amounts of man controlled water from the hill side above, after operation had ceased. Sampling was undertaken with a soil sampling equipment up to a depth of 8 metre. The samples were analyzed by x-ray diffraction and ICP-MS. Sampling observation in the field showed a zonation inverse, known in humid climates zones, in which the oxidation zone lies above an accumulation zone and a basal primary zone. In the studied tailings the stratigraphic column changes from a homogenous primary zone at the top, to an inhomogenous zone with intercalations of oxidized layers, to a very homogenous oxidation zone at 5-8 metre depth. The pH changes from 7-8 to 4 and the grain size from fine sandy to clayey between the primary and the oxidation zone. These zones are directly related to the water level in the tailings. X-ray diffraction analysis has confirmed that sulphides such as pyrite are only present in the primary zone; whereas gypsum and jarosite are present in the oxidation zone. The latter indicate the influence of sulphate rich acid solutions, resulting from the oxidation of pyrite (known as acid mine drainage - AMD). The element distribution indicates also a sulfide oxidation zone. The distribution of environmentally unhealthy heavy metals shows an accumulation at the uppermost parts of the oxidation zone, as a result of "unspecified" adsorption (surface) on the Fe(IIl)hydroxides and / or of sulphide precipitation. Below in the homogenous oxidation zone, heavy metal distribution is also homogenous and the metal contents are much higher than in the primary zone, which indicates a "specified" adsorption (incorporation in the crystal system, stable at low pH) and a geochemical equilibrium. The results show clearly that the geochemical processes in the studied tailings are directly related to the man controlled water input. The detected processes are related to pyrite oxidation and show a strong mobilization of all types of elements. The distribution of elements is interpreted to indicate an upwards migrating oxidation zone, characterized by the precipitation of Fe(IIl)hydroxides from Fe(II), metal rich solutions, and a water flow confined to the top of the oxidation zone

Development of imaging-based risk scores for prediction of intracranial haemorrhage and ischaemic stroke in patients taking antithrombotic therapy after ischaemic stroke or transient ischaemic attack: a pooled analysis of individual patient data from cohort studies

Background Balancing the risks of recurrent ischaemic stroke and intracranial haemorrhage is important for patients treated with antithrombotic therapy after ischaemic stroke or transient ischaemic attack. However, existing predictive models offer insufficient performance, particularly for assessing the risk of intracranial haemorrhage. We aimed to develop new risk scores incorporating clinical variables and cerebral microbleeds, an MRI biomarker of intracranial haemorrhage and ischaemic stroke risk.Methods We did a pooled analysis of individual-patient data from the Microbleeds International Collaborative Network (MICON), which includes 38 hospital-based prospective cohort studies from 18 countries. All studies recruited participants with previous ischaemic stroke or transient ischaemic attack, acquired baseline MRI allowing quantification of cerebral microbleeds, and followed-up participants for ischaemic stroke and intracranial haemorrhage. Participants not taking antithrombotic drugs were excluded. We developed Cox regression models to predict the 5-year risks of intracranial haemorrhage and ischaemic stroke, selecting candidate predictors on biological relevance and simplifying models using backward elimination. We derived integer risk scores for clinical use. We assessed model performance in internal validation, adjusted for optimism using bootstrapping.Findings The included studies recruited participants between Aug 28, 2001, and Feb 4, 2018. 15 766 participants had follow-up for intracranial haemorrhage, and 15 784 for ischaemic stroke. Over a median follow-up of 2 years, 184 intracranial haemorrhages and 1048 ischaemic strokes were reported. The risk models we developed included cerebral microbleed burden and simple clinical variables. Optimism-adjusted c indices were 0.73 (95% CI 0.69-0.77) with a calibration slope of 0.94 (0.81-1.06) for the intracranial haemorrhage model and 0.63 (0.62-0.65) with a calibration slope of 0.97 (0.87-1.07) for the ischaemic stroke model. There was good agreement between predicted and observed risk for both models.Interpretation The MICON risk scores, incorporating clinical variables and cerebral microbleeds, offer predictive value for the long-term risks of intracranial haemorrhage and ischaemic stroke in patients prescribed antithrombotic therapy for secondary stroke prevention; external validation is warranted. Copyright (C) 2021 Elsevier Ltd. All rights reserved

Orbital controls and high-resolution cyclostratigraphy of Late Jurassic Early-Cretaceous in the Neuquén Basin

Detailed cyclostratigraphic analyses have been made from seven Tithonian–Hauterivian sections of the Vaca Muerta and Agrio Formations, exposed in southern Mendoza area of the Neuquén Basin. Both lithostratigraphic units are characterized by decimeter-scale rhythmic alternations of marlstones and limestones, showing a well-ordered hierarchy of cycles, including elementary cycles, bundles, and superbundles. According to biostratigraphic data, elementary cycles have a periodicity of ~18–21 ky, which correlates with the precessional cycle of the Earth’s axis. Spectral analysis based on time series of elementary cycle thicknesses allowed us to identify frequencies of ~400 ky, and ~90–120 ky, which we interpret as the modulation of the precessional cycle by the Earth’s orbital eccentricity. A third band frequency of ~40 ky was also identified that can be assigned to the obliquity cycle. Cyclostratigraphy enabled the construction of almost continuous floating astronomical time scale for the Tithonian–Hauterivian, for which a minimum duration of 5.67 myr for the Tithonian, 5.27 myr for the Berriasian, >3.45 myr for the Valanginian, and 5.96 myr for the Hauterivian have been assessed. Additionally, the likely transference mechanisms of the orbital signal to the sedimentary record are analyzed, proposing the coexistence of carbonate exportation and dilution as the dominant mechanisms.Fil: Kietzmann, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Iglesia Llanos, Maria Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Kohan Martinez, Melisa. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; Argentin