A Survey on Metamorphic Testing

A test oracle determines whether a test execution reveals a fault, often by comparing the observed program output to the expected output. This is not always practical, for example when a program's input-output relation is complex and difficult to capture formally. Metamorphic testing provides an alternative, where correctness is not determined by checking an individual concrete output, but by applying a transformation to a test input and observing how the program output “morphs” into a different one as a result. Since the introduction of such metamorphic relations in 1998, many contributions on metamorphic testing have been made, and the technique has seen successful applications in a variety of domains, ranging from web services to computer graphics. This article provides a comprehensive survey on metamorphic testing: It summarises the research results and application areas, and analyses common practice in empirical studies of metamorphic testing as well as the main open challenges

The Performance of SiO2 and TiO2 Nanoparticles as Lubricant Additives in Sunflower Oil

In recent years, there has been growing concern regarding the use of petroleum-based lubricants. This concern has generated interest in readily biodegradable fluids such as vegetable oils. The present work evaluated the rheological and tribological characteristics of sunflower oil modified with silicon dioxide (SiO2) and titanium dioxide (TiO2) nanoparticles as lubricant additives at different concentrations. A parallel plate rheometer was used to evaluate the eects of concentration and shear rate on the shear viscosity, and the experimental data was compared with conventional models. The wear protection and friction characteristics of the oil-formulations were evaluated by conducting block-on-ring sliding tests. Surface analysis-based instruments, including scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and profilometry, were used to characterize the morphology and structure of the worn surfaces. The experimental results showed that the coeffcient of friction decreased with the addition of SiO2 and TiO2 nanoparticles by 77.7% and 93.7%, respectively when compared to base sunflower oil. Furthermore, the volume loss was lowered by 74.1% and 70.1%, with the addition of SiO2 and TiO2 nanoparticles, respectively. Based on the experimental results, the authors conclude that modified sunflower oil enhanced with nanoparticles has the potential for use as a good biodegradable lubricant

Fighting the disagreement in Explainable Machine Learning with consensus

Machine learning (ML) models are often valued by the accuracy of their predictions. However, in some areas of science, the inner workings of models are as relevant as their accuracy. To understand how ML models work internally, the use of interpretability algorithms is the preferred option. Unfortunately, despite the diversity of algorithms available, they often disagree in explaining a model, leading to contradictory explanations. To cope with this issue, consensus functions can be applied once the models have been explained. Nevertheless, the problem is not completely solved because the final result will depend on the selected consensus function and other factors. In this paper, six consensus functions have been evaluated for the explanation of five ML models. The models were previously trained on four synthetic datasets whose internal rules were known in advance. The models were then explained with model-agnostic local and global interpretability algorithms. Finally, consensus was calculated with six different functions, including one developed by the authors. The results demonstrated that the proposed function is fairer than the others and provides more consistent and accurate explanations.Comment: 21 pages, 7 figure

Analysis of the tautomeric equilibrium of two red monoazo dyes by UV–Visible, Raman and SERS spectroscopies

Acid Red 26 and Acid Red 18 are two early synthetic dyes belonging to the monazo dye class. The molecular structure of this class of dyes is characterized by the chromophoric azo group (N[dbnd]N) generally attached to benzene or naphthalene derivatives containing electron withdrawing and/or donating groups as substituents. As both red dyes have an OH group in ortho- position respect to the azo group, they undergo an azo-hydrazone tautomerism. In this work, UV–Vis, Raman and SERS spectroscopic analysis of the red dye solutions were carried out at different pH conditions, in order to evaluate the preponderance of one tautomer over the other as a function of the pH. Different experimental conditions were tested in order to find the best ones for the detection of both dyes. Thus, Raman spectra of the powder and aqueous solutions of AR26 and AR18 were obtained at the natural pH of the solutions, and above and below that value. The SERS analysis of the dye solutions were carried out at various pH values between 2 and 10, and with excitation at 442, 532 and 633 nm. The molecular structure and the theoretical Raman spectra of the two tautomers of both red dyes were calculated by DFT methods. The obtained results were used for the assignment of the Acid Red 26 and Acid Red 18 vibrational modes. Finally, a textile sample dyed with AR18 was analyzed by SERS

Assessment of volaemia using ultrasound of the heart

In humans, echocardiography is the standard of care in patients in shock, helping intensivists to characterize the haemodynamic disorder, to select a therapeutic approach and to monitor the response to treatment. In veterinary medicine the use of ultrasonography is limited to the assessment of the caudal vena cava (CVC), as a method of estimating volaemia. The current study aimed to explore whether echocardiographic measurements can be useful in the diagnosis and monitoring of the response to treatment in cases of suspected hypovolaemia. The study cohort comprised of eighteen dogs presented to an out of hours service for suspicion of hypovolaemia, and the control cohort consisted of nineteen dogs presented for echocardiography that were diagnosed as not having substantial cardiac disease. Data from the physical exam (mucous membrane colour, heart rate, pulse quality, capillary refill time), systolic blood pressure (SBP), and laboratory findings (lactate concentration (LAC), total protein (TP), packed cell volume (PCV)) were recorded for the study cohort and used to decide if the patients were suspected to be hypovolaemic. Dogs from both cohorts were scanned conscious in right lateral recumbency. Ultrasonographic measurements comprised: maximal diameter of the CVC (CVCmax), CVC collapsibility index (CVC CI), CVC to aorta ratio (CVC/Ao), maximal dimension of left atrium to aorta ratio (LAmajor/Ao), left ventricular internal diameter in diastole normalized for bodyweight by allometric scaling (LVIDdN), end diastolic ventricular volume index (EDVI), and stroke volume (SV) obtained from the aortic velocity- time integral. All the physical exam variables, laboratory tests and ultrasonographic measurements were measured again in the study cohort after the administration of intravenous fluid therapy. The median time to perform the ultrasonographic protocol was 4 (3-4) minutes. The best discriminator to differentiate between cases and controls was the EDVI (P=0.047), however the specificity (42%) and sensitivity (53%) were very low. The heart rate, capillary refill time, TP, PCV, CVCmax, CVC/Ao, LAmajor/Ao, LVIDdN, EDVI and SV were significantly different (P≤0.05) after treatment. This study shows that a simplified echocardiographic protocol, that can be performed in a limited time can provide useful information about the volume status of the conscious, spontaneously breathing, clinically ill dog and can be helpful in monitoring the response to treatment

Implementación de talleres recreativos y ludicos para la mejora de prácticas en procesos de seguridad ocupacional y clima laboral de los empleados del área logística de una empresa de alimentos dedicada a abastecer las aeronaves

El presente trabajo de investigación surge de la necesidad de una empresa del sector de alimentos, de llegar a los empleados con una metodología innovadora para la organización con el fin de formar y a la vez motivar a los empleados pertenecientes del área de logística ya que es el área donde más se presenta rotación de personal y accidentes de trabajo de alto grado esto debida a inconformismos esta empresa está ubicada sobre la localidad de Fontibón en cercanías al aeropuerto internacional El dorado. Por ello el proyecto implementa como posible solución el implementar una metodología lúdico recreativa por medio de talleres para lo cual se generó una planificación de 10 talleres pensando en horarios en los que los empleados tengan menos carga laboral, cada uno de estos talleres llevo un registro de asistencia, unas evidencias fotográficas y un diario de campo con el fin de identificar situaciones significativas que ayudan a reconocer la realidad del proyecto para con el momento

Expression of Homing Receptors in IgM+IgD+CD27+ B Cells and Their Frequencies in Appendectomized and/or Tonsillectomized Individuals

Q4Q3Pacientes apendicectomizados y/o amigdalectomizadosBackground: In humans, blood circulating IgM+IgD+CD27+ B cells are considered analogous to those described in the marginal zone of the spleen and are involved in important immunological processes. The homing receptors they express, and the organs involved in their development (for example, intestinal organs in rabbits) are only partially known. We recently reported that this population is heterogeneous and composed of at least two subsets: one expressing high levels of IgM – IgMhi B cells – and another low levels – IgMlo B cells. Objectives: To evaluate the expression of homing receptors on IgD+CD27+ IgMhi and IgMlo B cells and quantify their frequencies in blood of control and appendectomized and/or tonsillectomized volunteers. Materials and Methods: Using spectral flow cytometry, the simultaneous expression of 12 previously reported markers that differentiate IgMhi B cells and IgMlo B cells and of α4β7, CCR9, CD22 and CCR10 were evaluated in blood circulating B cells of control and appendectomized and/or tonsillectomized volunteers. Results The existence of phenotypically defined IgMlo and IgMhi B cell subsets was confirmed. They differentially expressed intestinal homing receptors, and the expression of α4β7 and CCR9 seems to determine new IgM subpopulations. IgMlo and IgMhi B cells were detected at lower frequencies in the appendectomized and/or tonsillectomized volunteers relative to controls. Conclusions: Human blood circulating IgD+CD27+ IgMlo and IgMhi B cell subsets differentially express homing receptors, and it is necessary to investigate if mucosal organs are important in their development.https://orcid.org/0000-0002-0817-2718https://orcid.org/0000-0002-6973-7639https://orcid.org/0000-0002-0265-0563https://orcid.org/0000-0001-6623-5337Revista Internacional - IndexadaA2N