On the distribution of source code file sizes

Source code size is an estimator of software effort. Size is also often used to calibrate models and equations to estimate the cost of software. The distribution of source code file sizes has been shown in the literature to be a lognormal distribution. In this paper, we measure the size of a large collection of software (the Debian GNU/Linux distribution version 5.0.2), and we find that the statistical distribution of its source code file sizes follows a double Pareto distribution. This means that large files are to be found more often than predicted by the lognormal distribution, therefore the previously proposed models underestimate the cost of software

Ionospheric biases correction for coordinates derived from GPS single point positioning

Most GPS users employ low cost receivers. These receivers do not allow users to record the pseudorange that they observe, but the computed coordinates. This work presents an original and simple method to correct ionospheric biases introduced in GPS signals. The originality of this method is based on the fact that no pseudorange is needed to correct the biases, only the calculated coordinates are used. This distinguishes this method from other classic alternatives. This paper evaluates the efficiency of the method with the use of real data

Time domain reconstruction of sound speed and attenuation in ultrasound computed tomography using full wave inversion

Ultrasound computed tomography (USCT) is a non-invasive imaging technique that provides information about the acoustic properties of soft tissues in the body, such as the speed of sound (SS) and acoustic attenuation (AA). Knowledge of these properties can improve the discrimination between benign and malignant masses, especially in breast cancer studies. Full wave inversion (FWI) methods for image reconstruction in USCT provide the best image quality compared to more approximate methods. Using FWI, the SS is usually recovered in the time domain, and the AA is usually recovered in the frequency domain. Nevertheless, as both properties can be obtained from the same data, it is desirable to have a common framework to reconstruct both distributions. In this work, an algorithm is proposed to reconstruct both the SS and AA distributions using a time domain FWI methodology based on the fractional Laplacian wave equation, an adjoint field formulation, and a gradient-descent method. The optimization code employs a Compute Unified Device Architecture version of the software k-Wave, which provides high computational efficiency. The performance of the method was evaluated using simulated noisy data from numerical breast phantoms. Errors were less than 0.5% in the recovered SS and 10% in the AA. V

Chromatic induction and the layout of colours within a complex scene

AbstractA target’s apparent colour is influenced by the colours in its surrounding. If the surrounding consists of a single coloured surface, the influence is a shift ‘away’ from the surface’s colour. If the surface is more than 1° from the target area the shift is very small. If there are many surfaces, then not only the average luminance and chromaticity of the surfaces matters, but also the chromatic variability. It is not yet clear whether it makes any difference where the chromatic variability is within the scene, so we constructed stimuli in which the chromatic variability was restricted to certain regions. We found that it made very little difference where the chromatic variability was located. The extent to which the average colour of nearby surfaces influences the apparent colour of the target seems to depend on the average chromatic variability of the whole scene

Code smells survival analysis in web apps

Web applications are heterogeneous, both in their target platform (split across client and server sides) and on the formalisms they are built with, usually a mixture of programming and formatting languages. This heterogeneity is perhaps an explanation why software evolution of web applications (apps) is a poorly addressed topic in the literature. In this paper we focus on web apps built with PHP, the most widely used server-side programming language. We analyzed the evolution of 6 code smells in 4 web applications, using the survival analysis technique. Since code smells are symptoms of poor design, it is relevant to study their survival, that is, how long did it take from their introduction to their removal. It is obviously desirable to minimize their survival. In our analysis we split code smells in two categories: scattered smells and localized smells, since we expect the former to be more harmful than the latter. Our results provide some evidence that the survival of PHP code smells depends on their spreadness. We have also analyzed whether the survival curve varies in the long term, for the same web application. Due to the increasing awareness on the potential harm-fulness of code smells, we expected to observe a reduction in the survival rate in the long term. The results show that there is indeed a change, for all applications except one, which lead us to consider that other factors should be analyzed in the future, to explain the phenomenon.info:eu-repo/semantics/acceptedVersio

The Spanish SpaceWeather Service SeNMEs. A Case Study on the Sun-Earth Chain

Comunicación presentada en el Coimbra Solar Physics Meeting, 5-9 October 2015, Coimbra, PortugalThe Spanish Space Weather Service SeNMEs, www.senmes.es, is a portal created by the SRG-SW of the Universidad de Alcalá, Spain, to meet societal needs of near real-time space weather services. This webpage-portal is divided in different sections to fulfill users needs about space weather effects: radio blackouts, solar energetic particle events, geomagnetic storms and presence of geomagnetically induced currents. In less than one year of activity, this service has released a daily report concerning the solar current status and interplanetary medium, informing about the chances of a solar perturbation to hit the Earth’s environment. There are also two different forecasting tools for geomagnetic storms, and a daily ionospheric map. These tools allow us to nowcast a variety of solar eruptive events and forecast geomagnetic storms and their recovery, including a new local geomagnetic index, LDiñ, along with some specific new scaling. In this paper we also include a case study analysed by SeNMEs. Using different high resolution and cadence data from space-borne solar telescopes SDO, SOHO and GOES, along with ionospheric and geomagnetic data, we describe the Sun-Earth feature chain for the event.MINECO project AYA2013-47735PPeer reviewe

Capsule endoscopy interpretation: the role of physician extenders

Background and aims: capsule endoscopy (CE) allows for a new era in small-bowel examination. Nevertheless, physicians’ time for CE-interpretation remains longer than desirable. Alternative strategies to physicians have not been widely investigated. The aim of this study was to evaluate the accuracy of physician extenders in CE-interpretation. Material and methods: one CE-experienced gastroenterologist and two physician extenders reviewed independently 20 CEprocedures. Each reader was blinded to the findings of their colleagues. A consensus formed by the readers and a second CE-experienced gastroenterologist was used as gold standard. Number, type and location of images selected, character of CEexams and their relationship with indications were recorded. Gastric emptying time (GEt), small-bowel transit time (SBTt) and time spent by readers were also noted. Results: sensitivity and specificity for “overall” lesions was 79 and 99% for the gastroenterologist; 86 and 43% for the nurse; and 80 and 57% for the resident. All 34 “major” lesions considered by consensus were found by the readers. Agreement between consensus and readers for images classification and procedures interpretation was good to excellent (κ from 0.55 to 1). No significant differences were found in the GEt and SBTt obtained by consensus and readers. The gastroenterologist was faster than physician extenders (mean time spent was 51.9 ± 13.5 minutes versus 62.2 ± 19 and 60.9 ± 17.1 for nurse and resident, respectively; p < 0.05). Conclusions: physician extenders could be the perfect complement to gastroenterologists for CE-interpretation but gastroenterologists should supervise their findings. Future cost-efficacy analyses are required to assess the benefits of this alternative

Asymptotic expansions of the solutions of the Cauchy problem for nonlinear parabolic equations

Let $u$ be a solution of the Cauchy problem for the nonlinear parabolic equation $$\partial_t u=\Delta u+F(x,t,u,\nabla u) \quad in \quad{\bf R}^N\times(0,\infty), \quad u(x,0)=\varphi(x)\quad in \quad{\bf R}^N,$$ and assume that the solution $u$ behaves like the Gauss kernel as $t\to\infty$. In this paper, under suitable assumptions of the reaction term $F$ and the initial function $\varphi$, we establish the method of obtaining higher order asymptotic expansions of the solution $u$ as $t\to\infty$. This paper is a generalization of our previous paper, and our arguments are applicable to the large class of nonlinear parabolic equations

Viabilidad del uso de fotodetectores SiPM en sistemas PET/IRM

Actas de: XXVIII Congreso Anual de la Sociedad Española de Ingeniería Biomédica (CASEIB 2010). Madrid, 24-26 de noviembre de 2010.El fotomultiplicador de silicio (SiPM) es un detector compuesto por una matriz de fotodiodos funcionando en modo avalancha, también conocido como modo Geiger. Se trata de un dispositivo de alta eficiencia en la detección de fotones que, por tratarse de un semiconductor, es compacto, teóricamente insensible a campos magnéticos, y de bajo coste. Además, la electrónica asociada es sencilla y podría integrarse en el mismo dispositivo. Estas características hacen de este componente un buen candidato para construir detectores de rayos gamma para imagen médica nuclear (PET y SPECT). En este trabajo se evalúan las prestaciones de tres detectores diferentes de 1 x 1 mm2 y una matriz de 2 x 2 SiPMs (6 x 6 mm² área activa total). Se ha analizado la dependencia de los parámetros operacionales del dispositivo en presencia de campos magnéticos estáticos intensos y de los campos de radiofrecuencia generados por un sistema de IRM preclínico, en condiciones extremas de trabajo en cuanto a intensidad y frecuencia de conmutación de los gradientes de campo. Al mismo tiempo se ha verificado que la presencia de estos dispositivos en la zona de imagen de la RM no afecta a la calidad de la misma.Este trabajo ha sido financiado por los proyectos TEC2007-64731, TEC 2008-06715-C02-1 del Ministerio de Ciencia e Innovación, por la RETIC-RECAVA del Ministerio de Sanidad y Consumo, por el programa ARTEMIS S2009/DPI-1802 de la Comunidad de Madrid, por el proyecto europeo FMT-XCT FP7-201792, los programas FPA2007-62216, TEC2008-06715-C02-01, UCM (Grupos UCM; 910059), CPAN (Consolider-Ingenio 2010) y CSPD-2007-00042. Parte de los cálculos realizados en este trabajo se han hecho en el ‘‘High Capacity Cluster for Physical Techniques’’ de la UCM, financiados en parte por la UE bajo el programa FEDER, y en otra parte por la UCM.Publicad

Self-similarity and long-time behavior of solutions of the diffusion equation with nonlinear absorption and a boundary source

This paper deals with the long-time behavior of solutions of nonlinear reaction-diffusion equations describing formation of morphogen gradients, the concentration fields of molecules acting as spatial regulators of cell differentiation in developing tissues. For the considered class of models, we establish existence of a new type of ultra-singular self-similar solutions. These solutions arise as limits of the solutions of the initial value problem with zero initial data and infinitely strong source at the boundary. We prove existence and uniqueness of such solutions in the suitable weighted energy spaces. Moreover, we prove that the obtained self-similar solutions are the long-time limits of the solutions of the initial value problem with zero initial data and a time-independent boundary source