Contracts in Practice

Contracts are a form of lightweight formal specification embedded in the program text. Being executable parts of the code, they encourage programmers to devote proper attention to specifications, and help maintain consistency between specification and implementation as the program evolves. The present study investigates how contracts are used in the practice of software development. Based on an extensive empirical analysis of 21 contract-equipped Eiffel, C#, and Java projects totaling more than 260 million lines of code over 7700 revisions, it explores, among other questions: 1) which kinds of contract elements (preconditions, postconditions, class invariants) are used more often; 2) how contracts evolve over time; 3) the relationship between implementation changes and contract changes; and 4) the role of inheritance in the process. It has found, among other results, that: the percentage of program elements that include contracts is above 33% for most projects and tends to be stable over time; there is no strong preference for a certain type of contract element; contracts are quite stable compared to implementations; and inheritance does not significantly affect qualitative trends of contract usage

Effect of RecA inactivation and detoxification systems on the evolution of ciprofloxacin resistance in Escherichia coli

Background Suppression of SOS response and overproduction of reactive oxygen species (ROS) through detoxification system suppression enhance the activity of fluoroquinolones. Objectives To evaluate the role of both systems in the evolution of resistance to ciprofloxacin in an isogenic model of Escherichia coli. Methods Single-gene deletion mutants of E. coli BW25113 (wild-type) (ΔrecA, ΔkatG, ΔkatE, ΔsodA, ΔsodB), double-gene (ΔrecA-ΔkatG, ΔrecA-ΔkatE, ΔrecA-ΔsodA, ΔrecA-ΔsodB, ΔkatG-ΔkatE, ΔsodB-ΔsodA) and triple-gene (ΔrecA-ΔkatG-ΔkatE) mutants were included. The response to sudden high ciprofloxacin pressure was evaluated by mutant prevention concentration (MPC). The gradual antimicrobial pressure response was evaluated through experimental evolution and antibiotic resistance assays. Results For E. coli BW25113 strain, ΔkatE, ΔsodB and ΔsodB/ΔsodA mutants, MPC values were 0.25 mg/L. The ΔkatG, ΔsodA, ΔkatG/katE and ΔrecA mutants showed 2-fold reductions (0.125 mg/L). The ΔkatG/ΔrecA, ΔkatE/ΔrecA, ΔsodA/ΔrecA, ΔsodB/ΔrecA and ΔkatG/ΔkatE/ΔrecA strains showed 4–8-fold reductions (0.03–0.06 mg/L) relative to the wild-type. Gradual antimicrobial pressure increased growth capacity for ΔsodA and ΔsodB and ΔsodB/ΔsodA mutants (no growth in 4 mg/L) compared with the wild-type (no growth in the range of 0.5–2 mg/L). Accordingly, increased growth was observed with the mutants ΔrecA/ΔkatG (no growth in 2 mg/L), ΔrecA/ΔkatE (no growth in 2 mg/L), ΔrecA/ΔsodA (no growth in 0.06 mg/L), ΔrecA/ΔsodB (no growth in 0.25 mg/L) and ΔrecA/ΔkatG/ΔkatE (no growth in 0.5 mg/L) compared with ΔrecA (no growth in the range of 0.002–0.015 mg/L). Conclusions After RecA inactivation, gradual exposure to ciprofloxacin reduces the evolution of resistance. After suppression of RecA and detoxification systems, sudden high exposure to ciprofloxacin reduces the evolution of resistance in E. coli.Plan Nacional de I+D+i 2013-2016 and the Instituto de Salud Carlos III (projects and PI17/01501 and PI20-00239)Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI; RD16/0016/0001 and REIPI RD16/ 0016/0009

Representación del álgebra de Lie, leyes de conservación y algunas soluciones invariantes para una ecuación de Emden-Fowler generalizada

All generators of the optimal algebra associated with a generalization of the Endem-Fowler equation are showed; some of them allow to give invariant solutions. Variational symmetries and the respective conservation laws are also showed. Finally, a representation of Lie symmetry algebra is showed by groups of matrices.Se muestran todos los generadores del álgebra óptima asociados con una generalización de la ecuación de Endem-Fowler; algunos de ellos permiten dar soluciones invariantes. También se muestran las simetrías variacionales y las respectivas leyes de conservación. Finalmente, se muestra una representación del álgebra de simetría de Lie mediante grupos de matrices

Clasificación del álgebra de Lie, leyes de conservación y soluciones invariantes para un caso particular de la ecuación generalizada e Levinson-Smith

In this study, we examine a specific instance of the generalized Levinson-Smith equation, which is linked to the Liènard equation and holds significant importance from the perspectives of physics, mathematics, and engineering. This underlying equation has practical applications in mechanics and nonlinear dynamics and has been extensively explored in the qualitative scheme. Our approach involves applying the Lie group method to this equation. By doing so, we derive the optimal generating operators for the system that pertain to the specific instance of the generalized Levinson-Smith equation. These operators are then used to define all invariant solutions associated with the equation. In addition, we demonstrate the variational symmetries and corresponding conservation laws using Noether's theorem. Finally, we categorize the Lie algebra related to the given equation.En este estudio, examinamos una instancia específica de la ecuación generalizada de Levinson-Smith, que está vinculada con la ecuación de Liènard y tiene una gran importancia desde las perspectivas de la física, las matemáticas y la ingeniería. Esta ecuación subyacente tiene aplicaciones prácticas en mecánica y dinámica no lineal, y ha sido ampliamente explorada en el esquema cualitativo. Nuestro enfoque implica aplicar el método de grupos de Lie a esta ecuación. Al hacerlo, obtenemos los operadores generadores óptimos del sistema que se refieren a la instancia específica de la ecuación generalizada de Levinson-Smith. Luego, se utilizan estos operadores para definir todas las soluciones invariantes asociadas con la ecuación. Además, demostramos las simetrías variacionales y las leyes de conservación correspondientes utilizando el teorema de Noether. Finalmente, categorizamos el álgebra de Lie relacionada con la ecuación dada

Osteomielitis crónica de extremidades inferiores en pacientes ancianos: colgajo sóleo, una opción efectiva

La osteomielitis crónica (OC) en extremidades inferiores afecta al hueso y tejidos blandos circundantes, produciéndose úlceras crónicas que exponen el hueso necrosado. El tratamiento de la OC combina: antibióticos, desbridamiento-estabilización ósea, y una adecuada cobertura cutánea. La reconstrucción de las pérdidas de sustancia localizadas en el tercio medio de la pierna puede realizarse con colgajos fasciocutáneos, colgajos libres, colgajos en piernas cruzadas y colgajos locales musculares. La edad avanzada del paciente es un factor importante a considerar para la indicación de la técnica reparadora. El colgajo sóleo tiene múltiples ventajas: rica vascularización, corto tiempo quirúrgico, postoperatorio cómodo para el paciente y mínima limitación funcional. Presentamos 2 casos de pacientes ancianos con defectos osteocutáneos tibiales secundarios a OC, en ambos casos la cobertura del defecto se realizó con el colgajo muscular sóleo, la evolución clínica fue favorable y la recuperación funcional total.Cronic osteomyelitis (CO) in lower legs involves tibial-fibular bones and soft tissues around, with cronic ulcers by necrosed bone exposure. CO treatment combines: antibiotics, removes necrotic bone, bony stabilization and an adequate soft tissue coverage. Soft tissue loss reconstruction in the medium third of the legs can be made with fasciocutaneous flaps, free flaps, cross leg flaps and local muscle flaps. Elderly age is an important condition for the reconstruction procedure indication. Soleus muscle flap has multiple advantages: great blood supply, short surgical time, comfortable postoperative and minimum functional sequels. Two cases: Both elderly patients with osteocutaneous defects in tibia, by CO. Treatment coverage was performed with soleus muscle flap. Clinic course increased positively and the patients got completely functional restitution

Traumatismos de partes blandas en la muñeca: cobertura fasciocutánea

Las pérdidas de sustancia traumática localizadas en la muñeca afectan frecuentemente a los tendones, vasos y nervios. Estas lesiones requieren un tratamiento reparador de las estructuras lesionadas y una cobertura adecuada que permita el deslizamiento de los tendones, y proporcione protección neurovascular segura. El colgajo fasciocutáneo basado en perforantes de la arteria cubital aporta piel, tejido subcutáneo y fascia sobre las estructuras expuestas en la muñeca tanto en la cara palmar como dorsal. Presentamos cuatro casos de traumatismos de partes blandas en la muñeca, en ellos tras la reparación neurotendinosa requerida, se optó por la cobertura final mediante el colgajo fasciocutáneo cubito-dorsal. Destacamos la versatilidad de estos colgajos, su fácil ejecución, mínima secuela estética y la posibilidad de iniciar precozmente el tratamiento rehabilitador, consiguiendo así una mejor recuperación funcional del paciente.Traumatic soft tissue loss in wrist usually involves tendons, vessels and nerves. These injuries need the adequate reconstructive treatment and the safe coverage which lets to slide the tendons and it gives a safe protection to neurovascular structures. The fasciocutaneous flap based in perforator branches of the ulnar artery brings skin, fat and fascia enough over the exposed tissues in the dorsal or volar surface of the wrist. We report four cases of traumatic lesions in soft tissues of the wrist, in all of them the fasciocutaneous dorsal cubital flap was the option for the end coverage. We emphasize the versatility of these flaps, its easy ejecution, the minimal aesthetic sequel and the early rehabilitation beginning, so we obtain the best functional restitution for the patien

Till death (or an intruder) do us part: intrasexual-competition in a monogamous Primate

Polygynous animals are often highly dimorphic, and show large sex-differences in the degree of intra-sexual competition and aggression, which is associated with biased operational sex ratios (OSR). For socially monogamous, sexually monomorphic species, this relationship is less clear. Among mammals, pair-living has sometimes been assumed to imply equal OSR and low frequency, low intensity intra-sexual competition; even when high rates of intra-sexual competition and selection, in both sexes, have been theoretically predicted and described for various taxa. Owl monkeys are one of a few socially monogamous primates. Using long-term demographic and morphological data from 18 groups, we show that male and female owl monkeys experience intense intra-sexual competition and aggression from solitary floaters. Pair-mates are regularly replaced by intruding floaters (27 female and 23 male replacements in 149 group-years), with negative effects on the reproductive success of both partners. Individuals with only one partner during their life produced 25% more offspring per decade of tenure than those with two or more partners. The termination of the pair-bond is initiated by the floater, and sometimes has fatal consequences for the expelled adult. The existence of floaters and the sporadic, but intense aggression between them and residents suggest that it can be misleading to assume an equal OSR in socially monogamous species based solely on group composition. Instead, we suggest that sexual selection models must assume not equal, but flexible, context-specific, OSR in monogamous species.Wenner-Gren Foundation, L.S.B. Leakey Foundation, the National Geographic Society, National Science Foundation (BCS- 0621020), the University of Pennsylvania Research Foundation and the Zoological Society of San Diego, German Science Foundation (HU 1746-2/1

Úlceras por presión en pacientes traumatológicos: prevención basada en la evidencia médica

Las úlceras por presión (UPP) suponen una complicación importante que puede afectar a pacientes cuya movilidad está limitada. El tratamiento quirúrgico de las fracturas en pacientes ancianos y el encamamiento prolongado pueden ser predisponentes de lesiones por decúbito. En este trabajo de revisión buscamos las medidas de prevención de UPP basadas en la evidencia médica. La Medicina Basada en la Evidencia (MBE) propone utilizar la mejor evidencia científica y clínica sobre las UPP, según la cual, la prevención es el objetivo fundamental en estos pacientes. Se destaca en la literatura relativa a las úlceras por presión que las medidas de prevención con evidencia médica probada incluyen: valoración integral del paciente, identificación del riesgo, reconocer el estadio de la UPP, aminorar el efecto de la presión, evaluar el estado nutricional, eliminar el exceso de humedad (incontinencia), evitar encamamientos prolongados y preservar la integridad de la piel.Pressure sores are an important complication, which can affects to patients with restricted motion. Surgical treatment of elderly people with fractures in addition prolonged time lying in same position are able to develop bedsores. This review paper searches the prevention features of pressure sores in evidence based medicine. Evidence Based Medicine proposes the best clinical and scientifical evidence available about to pressure sores, being prevention the main goal in these patients. The results founded in the literature relative to pressure sores affirms these are the facts in evidence based medicine: the general approach of the patient, recognising risk, staging pressure sores, reducing pressure effect, assessing nutritional status, avoiding excess moisture (incontinence) reducing bed rest and preserving the integrity of the skin

Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA

[EN] A proper diagnosis of the state of an induction motor is of great interest to industry given the great importance of the extended use of this motor. Presently, the use of this motor driven by a frequency converter is very widespread. However, operation by means of an inverter introduces certain difficulties for a correct diagnosis, which results in a signal with higher harmonic content and noise level, which makes it difficult to perform a correct diagnosis. To solve these problems, this article proposes the use of a time-frequency technique known as Dragon Transform together with the functional ANOVA statistical technique to carry out a proper diagnosis of the state of the motor by working directly with the curves obtained from the application of the transform. A case study is presented showing the good results obtained by applying the methodology in which the state of the rotor bars of an inverter-fed motor is diagnosed considering three failure states and operating at different load levels.This research has been partially funded by the University of Valladolid.Fernández-Cavero, V.; García-Escudero, LA.; Pons Llinares, J.; Fernández-Temprano, MA.; Duque-Perez, O.; Morinigo-Sotelo, D. (2021). Diagnosis of Broken Rotor Bars during the Startup of Inverter-Fed Induction Motors Using the Dragon Transform and Functional ANOVA. Applied Sciences. 11(9):1-12. https://doi.org/10.3390/app1109376911211

Effects of human versus mouse leukemia inhibitory factor on the in vitro development of bovine embryos

Leukemia inhibitory factor (LIF) is a cytokine that shows conflicting effects on in vitro produced (IVP) bovine embryos. Bovine LIF (bLIF) has been cloned and used in culture, but there is no commercially available bLIF. Thus, researchers use human LIF (hLIF) to supplement the culture medium for bovine embryos because of its greater sequence homology compared to murine LIF (mLIF). We compared the effects of mLIF and hLIF on the development of bovine embryos in culture with the effects described for bLIF. Oocytes were matured and fertilized in vitro and cultured in modified synthetic oviduct fluid with BSA. On Day 6 post-insemination, morulae were cultured for 48 h in the presence of: (1) mLIF, 100 ng ml−1; (2) hLIF, 100 ng ml−1; or (3) no LIF. Reduced blastocyst rates were observed on Day 8 for hLIF at the middle and expanded stages, while mLIF had no effect. In contrast, Day 8 blastocysts showed decreased cell counts both in terms of inner cell mass (ICM) and ICM/total cell proportions in the presence of mLIF, while hLIF had no effect. No changes were seen in trophectoderm (TE) and total cell counts. The increased hatching rates and TE cell counts previously described for bLIF, together with the disparate effects exhibited by hLIF and mLIF during blastocyst formation indicate these compounds are inappropriate to replace bLIF. We recommend that heterospecific LIF should not be used to supplement the culture medium for bovine embryo or embryonic stem cells