Estimating development effort in free/open source software projects by mining software repositories: A case study of OpenStack

Because of the distributed and collaborative nature of free/open source software (FOSS) projects, the development effort invested in a project is usually unknown, even after the software has been released. However, this information is becoming of major interest, especially-but not only-because of the growth in the number of companies for which FOSS has become relevant for their business strategy. In this paper we present a novel approach to estimate effort by considering data from source code management repositories. We apply our model to the OpenStack project, a FOSS project with more than 1,000 authors, in which several tens of companies cooperate. Based on data from its repositories and together with the input from a survey answered by more than 100 developers, we show that the model offers a simple, but sound way of obtaining software development estimations with bounded margins of error.Gregorio Robles, Carlos Cervig on and Jes us M. Gonz alez-Barahona, project SobreSale (TIN2011-28110). and The work of Daniel Izquierdo has been funded in part by the Torres Quevedo program (PTQ-12-05577

Algunos elementos de cultura material tardorromana procedentes de la "Villa" de San Blas (Olite, Navarra)

Se estudia un pequeño lote de materiales de fecha tardorromana (mediados del siglo IV, siglo V de J.C.) procedentes de la villa de San Blas (Olite). Se trata de fragmentos de DS- P gris (representadas las formas la, 5b, 15 y 18b), un huso de hierro y un recipiente de chapa de bronce. Tanto el plato D-S-P la, como el huso y el recipiente de bronce, pudieran provenir de un contexto funerario

Algunos elementos de armamento de la Segunda Edad del Hierro localizados en prospección en Navarra

Se estudia un pequeño lote de elementos de equipamiento militar de la Segunda Edad del Hierro. Todos ellos han sido localizados en prospección superficial en Navarra. Un pomo de puñal -de cuerna- procede de El Dorre (Artajona) y puede fecharse dentro del siglo IV a. de J.e. Parte de un vástago y de una punta de lanza - de hierro- y una escama de coraza -de aleación de cobre- proceden de Cabezo Lobo (Bardenas Reales) y podrían fecharse en el siglo 11 a. de J.e. o a finales del anterior

La necrópolis de San Pelayo (Alegría-Dulantzi, Álava) y la cuestión de la fecha de inicio de las necrópolis de tipo merovingio en Álava

En este artículo se discute, fundamentalmente, la fecha de establecimiento de las dos necrópolis de tipo merovingio descubiertas, por el momento, en Álava. De las evidencias publicadas hasta ahora por su excavador, A. Azkarate, parece desprenderse para Aldaieta (Nanclares de Gamboa) un inicio durante la primera mitad del siglo VI de J.e. Ligeramente más antigua parece la de San Pelayo (Alegría), fechada por la presencia de TSHT en sus ajuares a comienzos del mismo siglo. De esa manera, resulta factible conectar el origen de un área dependiente del reino franco en la zona occidental al sur de los Pirineos con el hundimiento del reino visigodo de Tolosa tras la batalla de Vouillé

La Extremadura Castellano-Leonesa: hacia la construcción de un modelo

Publicad

Revisión de los elementos de ajuar conservados del sepulcro megalítico de Unón (Clavijo, La Rioja)

En este artículo se procede a la revisión de los materiales conservados del megalito desaparecido de Uñón (Clavijo, La Rioja), entre los que destacan varios recipientes campaniformes

Effect of the presence of pyrite traces on silver behavior in natural porous media

In order to better understand the fate of the toxic element Ag(I), sorption of Ag(I) was studied from batch experiments, at different pHs (2–8) and at 298K. A pure quartz sand (99.999% SiO2) and “natural” quartz sand (99% SiO2, and traces of Fe, Al, Mn (hydr)oxides, of clays and of pyrite) were used as sorbents. The Ag(I) sorption behavior depends strongly on pH with isotherm shapes characteristic of Langmuir-type relationship for initial Ag concentration [Ag(I)], range between 5.0×10−7 and 1.0×10−3M. Even if the Ag (I) sorption capacity on pure quartz sand is very low compared to the natural quartz sands, its affinity is rather high. From speciation calculations, several sites were proposed: at pHi 4, 6 and 8, the first surface site is assumed to be due to iron (hydr)oxides while the second surface site is attributed to silanols. At pHi 2, sorption of Ag(I) was assumed to be on two surface sites of iron (hydr)oxides and a third surface site on silanol groups. Even if the sand is mainly composed of silica, the trace minerals play an important role in sorption capacity compared to silica. The conditional surface complexation constants of Ag(I) depend on pH. On the other hand, it is shown that the Ag speciation depends strongly on the history of “natural” quartz sand due to initial applied treatment, little rinsing or longer washing. In the presence of low amount of pyrite, strong complexes between Ag(I) and sulfur compounds such as thiosulfates due to oxidative dissolution of pyrite are formed what decreases Ag sorption capability. SEM–EDS analyses highlighted the surface complexation–precipitation of Ag2S and Ag(0) colloids which confirmed the important role of pyrite on Ag(I) speciation

Jejunal microvilli atrophy and reduced nutrient transport in rats with advanced liver cirrhosis: improvement by Insulin-like Growth Factor I

BACKGROUND: Previous results have shown that in rats with non-ascitic cirrhosis there is an altered transport of sugars and amino acids associated with elongated microvilli. These alterations returned to normal with the administration of Insulin-Like Growth Factor-I (IGF-I). The aims of this study were to explore the evolution of these alterations and analyse the effect of IGF-I in rats with advanced cirrhosis and ascites. Thus, jejunal structure and nutrient transport (D-galactose, L-leucine, L-proline, L-glutamic acid and L-cystine) were studied in rats with ascitic cirrhosis. METHODS: Advanced cirrhosis was induced by CCl(4 )inhalation and Phenobarbital administration for 30 weeks. Cirrhotic animals were divided into two groups which received IGF-I or saline during two weeks. Control group was studied in parallel. Jejunal microvilli were studied by electron microscopy. Nutrient transport was assessed in brush border membrane vesicles using (14)C or (35)S-labelled subtracts in the three experimental groups. RESULTS: Intestinal active Na(+)-dependent transport was significantly reduced in untreated cirrhotic rats. Kinetic studies showed a decreased V(max )and a reduced affinity for sugar and four amino acids transporters (expressed as an increased K(t)) in the brush border membrane vesicles from untreated cirrhotic rats as compared with controls. Both parameters were normalised in the IGF-I-treated cirrhotic group. Electron microscopy showed elongation and fusion of microvilli with degenerative membrane lesions and/or notable atrophy. CONCLUSIONS: The initial microvilli elongation reported in non ascitic cirrhosis develops into atrophy in rats with advanced cirrhosis and nutrient transports (monosaccharides and amino acids) are progressively reduced. Both morphological and functional alterations improved significantly with low doses of IGF-I