Mutation Testing as a Safety Net for Test Code Refactoring

Refactoring is an activity that improves the internal structure of the code without altering its external behavior. When performed on the production code, the tests can be used to verify that the external behavior of the production code is preserved. However, when the refactoring is performed on test code, there is no safety net that assures that the external behavior of the test code is preserved. In this paper, we propose to adopt mutation testing as a means to verify if the behavior of the test code is preserved after refactoring. Moreover, we also show how this approach can be used to identify the part of the test code which is improperly refactored

Senescent cells in the development of cardiometabolic disease

Purpose of review Senescent cells have recently been identified as key players in the development of metabolic dysfunction. In this review, we will highlight recent developments in this field and discuss the concept of targeting these cells to prevent or treat cardiometabolic diseases. Recent findings Evidence is accumulating that cellular senescence contributes to adipose tissue dysfunction, presumably through induction of low-grade inflammation and inhibition of adipogenic differentiation leading to insulin resistance and dyslipidaemia. Senescent cells modulate their surroundings through their bioactive secretome and only a relatively small number of senescent cells is sufficient to cause persistent physical dysfunction even in young mice. Proof-of-principle studies showed that selective elimination of senescent cells can prevent or delay the development of cardiometabolic diseases in mice. Summary The metabolic consequences of senescent cell accumulation in various tissues are now unravelling and point to new therapeutic opportunities for the treatment of cardiometabolic diseases

Analytical expressions for the conductance noise measured with four circular contacts placed in a square array

In the ideal case, noise measurements with four contacts minimize the contribution of the contact interface. There is a need to characterize conductance noise and noise correction factors for the different geometries provided with four contacts, as already is the case for resistivity measurements with van der Pauw structures. Here, we calculate the noise correction factors for two geometries with a pair of sensors and a pair of current driver electrodes placed in a square array. The first geometry investigated is a very large film compared to the distance L between four circular electrodes, which are placed in a square array far away from the borders of the film. The second is a square-shaped conductive film with side length L and provided with four quarter-circle corner contacts with radius l. The effect of the conductance noise in the film can be observed between current free sensors in a four-point measurement or between current carrying drivers in a two-point measurement. Our analytical expressions are based on approximations to solve the integrals (J·)2dA and |J|4dA for the voltage noise measured across a pair of sensors, SVQ, and across the drivers, SVD, respectively. The first and second integrands represent the squared dot product of the current density and adjoint current density and the modulus of the current density to the fourth power, respectively. The current density J in the samples is due to the current I passing through the driver contacts. The calculated expressions are applicable to samples with thickness tl0.1L. Hence, the disturbances in the neighborhood of the sensors on J and of the drivers on are ignored. Noise correction factors for two- and four-point measurements are calculated for sensors on an equipotential (transversal noise) with the driver contacts on the diagonal of a square and for sensors next to each other on one side of the square with the drivers next to each other on the other side of the square (longitudinal noise). In all cases the noise between the sensors is smaller and less sensitive to the contact size 2l/L than the noise between the drivers. The ratio SVQ/SVD becomes smaller with smaller contact radius l. Smaller sensors give a better suppression of interface noise at the contacts. But overly low 2l/L values result in overly high resistance between the sensors and too strong a contribution of thermal noise at the sensors. Therefore, equations are derived to calculate the current level needed to observe 1/f conductance fluctuations on top of the thermal noise. The results from the calculated analytical expressions show good agreement with experimental results obtained from the noise in carbon sheet resistance and numerical results. Transversal noise measurements on a square sample with corner contacts are recommended to characterize the 1/f noise of the layer. This is due to the increased current densities in the sample compared to the open structure, which result in easier detection of the 1/f on top of the thermal noise. ©2007 American Institute of Physic

Fermi Surface Properties of Low Concentration Cex_{x}La1−x_{1-x}B6_{6}: dHvA

The de Haas-van Alphen effect is used to study angular dependent extremal areas of the Fermi Surfaces (FS) and effective masses of Ce$_{x}$La$_{1-x}$B$_{6}$ alloys for $x$ between 0 and 0.05. The FS of these alloys was previously observed to be spin polarized at low Ce concentration ($x$ = 0.05). This work gives the details of the initial development of the topology and spin polarization of the FS from that of unpolarized metallic LaB$_{6}$ to that of spin polarized heavy Fermion CeB$_{6}$ .Comment: 7 pages, 9 figures, submitted to PR

Ferromagnetic Properties of ZrZn2_2

The low Curie temperature (T_C approx 28K) and small ordered moment (M_0 approx 0.17 mu_B f.u.^-1) of ZrZn2 make it one of the few examples of a weak itinerant ferromagnet. We report results of susceptibility, magnetization, resistivity and specific heat measurements made on high-quality single crystals of ZrZn2. From magnetization scaling in the vicinity of T_C (0.001<|T-T_C|/T_C<0.08), we obtain the critical exponents beta=0.52+/-0.05 and delta=3.20+/-0.08, and T_C=27.50+/-0.05K. Low-temperature magnetization measurements show that the easy axis is [111]. Resistivity measurements reveal an anomaly at T_C and a non-Fermi liquid temperature dependence rho(T)=rho_0+AT^n, where n=1.67+/-0.02, for 1<T<14K. The specific heat measurements show a mean-field-like anomaly at T_C. We compare our results to various theoretical models.Comment: submitted to PR

Evaluating the usability of a visual feature modeling notation

International audienceFeature modeling is a popular Software Product Line Engineering (SPLE) technique used to describe variability in a product family. A usable feature modeling tool environment should enable SPLE practitioners to produce good quality models, in particular, models that effectively communicate modeled information. FAMILIAR is a text-based environment for manipulating and composing Feature Models (FMs). In this paper we present extensions we made to FAMILIAR to enhance its usability. The extensions include a visualization of FMs, or more precisely , a feature diagram rendering mechanism that supports the use of a combination of text and graphics to describe FMs, their configurations, and the results of FM analyses. We also present the results of a preliminary evaluation of the environment's usability. The evaluation involves comparing the use of the extended environment with the previous text-based console-driven version. The preliminary experiment provides some evidence that use of the new environment results in increased cognitive effectiveness of novice users and improved quality of new FMs

Automated reasoning on feature models

Software Product Line (SPL) Engineering has proved to be an effective method for software production. However, in the SPL community it is well recognized that variability in SPLs is increasing by the thousands. Hence, an automatic support is needed to deal with variability in SPL. Most of the current proposals for automatic reasoning on SPL are not devised to cope with extra– functional features. In this paper we introduce a proposal to model and reason on an SPL using constraint programming. We take into account functional and extra–functional features, improve current proposals and present a running, yet feasible implementation

Interpretation of pre-morbid cardiac 3T MRI findings in overweight and hypertensive young adults

In young adults, overweight and hypertension possibly already trigger cardiac remodeling as seen in mature adults, potentially overlapping non-ischemic cardiomyopathy findings. To this end, in young overweight and hypertensive adults, we aimed to investigate changes in left ventricular mass (LVM) and cardiac volumes, and the impact of different body scales for indexation. We also aimed to explore the presence of myocardial fibrosis, fat and edema, and changes in cellular mass with extracellular volume (ECV), T(1) and T(2) tissue characteristics. We prospectively recruited 126 asymptomatic subjects (51% male) aged 27–41 years for 3T cardiac magnetic resonance imaging: 40 controls, 40 overweight, 17 hypertensive and 29 hypertensive overweight. Myocyte mass was calculated as (100%–ECV) * height(2.7)-indexed LVM. Absolute LVM was significantly increased in overweight, hypertensive and hypertensive overweight groups (104 ± 23, 109 ± 27, 112 ± 26 g) versus controls (87 ± 21 g), with similar volumes. Body surface area (BSA) indexation resulted in LVM normalization in overweights (48 ± 8 g/m(2)) versus controls (47 ± 9 g/m(2)), but not in hypertensives (55 ± 9 g/m(2)) and hypertensive overweights (52 ± 9 g/m(2)). BSA-indexation overly decreased volumes in overweight versus normal-weight (LV end-diastolic volume; 80 ± 14 versus 92 ± 13 ml/m(2)), where height(2.7)-indexation did not. All risk groups had lower ECV (23 ± 2%, 23 ± 2%, 23 ± 3%) than controls (25 ± 2%) (P = 0.006, P = 0.113, P = 0.039), indicating increased myocyte mass (16.9 ± 2.7, 16.5 ± 2.3, 18.1 ± 3.5 versus 14.0 ± 2.9 g/m(2.7)). Native T(1) values were similar. Lower T(2) values in the hypertensive overweight group related to heart rate. In conclusion, BSA-indexation masks hypertrophy and causes volume overcorrection in overweight subjects compared to controls, height(2.7)-indexation therefore seems advisable

Clinical importance of urinary sodium excretion in acute heart failure

Aims: Urinary sodium assessment has recently been proposed as a target for loop diuretic therapy in acute heart failure (AHF). We aimed to investigate the time course, clinical correlates and prognostic importance of urinary sodium excretion in AHF. Methods and results: In a prospective cohort of 175 consecutive patients with an admission for AHF we evaluated urinary sodium excretion 6 h after initiation of loop diuretic therapy. Clinical outcome was all-cause mortality or heart failure rehospitalization. Mean age was 71 ± 14 years, and 44% were female. Median urinary sodium excretion was 130 (67–229) mmol at 6 h, 347 (211–526) mmol at 24 h, and decreased from day 2 to day 4. Lower urinary sodium excretion was independently associated with male gender, younger age, renal dysfunction and pre-admission loop diuretic use. There was a strong association between urinary sodium excretion at 6 h and 24 h urine volume (beta = 0.702, P < 0.001). Urinary sodium excretion after 6 h was a strong predictor of all-cause mortality after a median follow-up of 257 days (hazard ratio 3.81, 95% confidence interval 1.92–7.57; P < 0.001 for the lowest vs. the highest tertile of urinary sodium excretion) independent of established risk factors and urinary volume. Urinary sodium excretion was not associated with heart failure rehospitalization. Conclusion: In a modern, unselected, contemporary AHF population, low urinary sodium excretion during the first 6 h after initiation of loop diuretic therapy is associated with lower urine output in the first day and independently associated with all-cause mortality