Constant of Motion for several one-dimensional systems and outlining the problem associated with getting their Hamiltonians

The constants of motion of the following systems are deduced: a relativistic particle with linear dissipation, a no-relativistic particle with a time explicitly depending force, a no-relativistic particle with a constant force and time depending mass, and a relativistic particle under a conservative force with position depending mass. The problem of getting the Hamiltonian for these systems is determined by getting the velocity as an explicit function of position and generalized linear momentum, and this problem can be solved a first approximation for the first above system.Comment: 15 pages, Te

The Second Wind in McArdle Patients: Fitness Matters

Glucogenosis tipo 5; Deficiencia de miofosforilasa; Umbral de ventilaciónGlycogenosis type 5; Myophosphorylase deficiency; Ventilatory thresholdGlucogenosi tipus 5; Deficiència de miofosforilasa; Llindar ventilatoriBackground: The “second wind” (SW) phenomenon—commonly referring to both an initial period of marked intolerance to dynamic exercise (e.g., brisk walking) that is not followed by perceived improvement and disappearance of previous tachycardia (i.e., the actual “SW”) until 6–10 min has elapsed—is an almost unique feature of McArdle disease that limits adherence to an active lifestyle. In this regard, an increase in the workload eliciting the SW could potentially translate into an improved patients’ exercise tolerance in daily life. We aimed to determine whether aerobic fitness and physical activity (PA) levels are correlated with the minimum workload eliciting the SW in McArdle patients—as well as with the corresponding heart rate value. We also compared the SW variables and aerobic fitness indicators in inactive vs. active patients. Methods: Fifty-four McArdle patients (24 women, mean ± SD age 33 ± 12 years) performed 12-min constant-load and maximum ramp-like cycle-ergometer tests for SW detection and aerobic fitness [peak oxygen uptake (VO2peak) and workload and ventilatory threshold] determination, respectively. They were categorized as physically active/inactive during the prior 6 months (active = reporting ≥150 min/week or ≥75 min/week in moderate or vigorous-intensity aerobic PA, respectively) and were also asked on their self-report of the SW. Results: Both peak and submaximal indicators of aerobic fitness obtained in the ramp tests were significantly correlated with the workload of the SW test, with a particularly strong correlation for the VO2peak and peak workload attained by the patients (both Pearson’s coefficients > 0.70). Twenty (seven women) and 24 patients (18 women) were categorized as physically active and inactive, respectively. Not only the aerobic fitness level [∼18–19% higher values of VO2peak (ml⋅kg–1⋅min–1)] but also the workload of the SW tests was significantly higher in active than in inactive patients. All the inactive patients reported that they experienced the SW during walking/brisk walking in daily life, whereas active patients only reported experiencing this phenomenon during more strenuous activities (very brisk walking/jogging and bicycling). Conclusion: A higher aerobic fitness and an active lifestyle are associated with a higher workload eliciting the so-called SW phenomenon in patients with McArdle disease, which has a positive impact on their exercise tolerance during daily living.Research by AL, CF-L, GN-G, MM, and TP was funded by the Instituto de Salud Carlos III (ISCIII) and Fondos Feder (grants PI18/00139, PI20/00645, PI18/00713, PI17/00093, and PI19/01313). CF-L and GN-G were supported by Miguel Servet contracts (CP18/00034 and CPII19/00021, respectively) from ISCIII. The funders had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the manuscript for publication

Adhesion mechanisms of Actinobacillus pleuropneumoniae to the porcine respiratory system and biofilm formation

Actinobacillus pleuropneumoniae is a Gram-negative bacterium and the causative agent of porcine pleuropneumonia, a highly contagious disease of pigs characterised by fibrinohaemorrhagic necrotising pneumonia. Although it has been well controlled in some developed countries, outbreaks can occur in pigs of all ages in contact with asymptomatic carriers, leading to significant economic losses to the swine industry due to the high morbidity and mortality rates. Adhesion is a critical step in the colonisation of the swine respiratory tract and the pathogenesis of the porcine pleuropneumonia; however, a literature review of this process is not available to date. Therefore, this review aims to provide information regarding the molecules that have been described in the adhesion of A. pleuropneumoniae to cells and tissues of the porcine respiratory tract. Since adhesion is the first step in biofilm formation, we included a section to describe the genes involved in this process; some of these genes could participate directly or indirectly in the adhesion of A. pleuropneumoniae to the porcine respiratory system. Although the role of biofilms in porcine pleuropneumonia is still not clear, these molecules could be considered in the future as candidates for vaccine development

Género, identidad de género y sistema de género: un recorrido conceptual desde la filosofía y las ciencias sociales

Este trabajo se realiza en el marco del proyecto de investigación “Conocimientos infantiles sobre la sociedad: estudio de casos sobre las representaciones acerca de las diferencias de género en niños y niñas de 10 y 11 años” (Secyt – UNLP). El objetivo de este artículo es presentar una sistematización sobre diferentes conceptualizaciones acerca de la noción de género desde diversas perspectivas teórico disciplinares, relevadas a partir de un primer rastreo bibliográfico. El recorrido realizado por las ideas de John Money, Robert Stoller, Simone de Beauvoir, Kate Millet, Gayle Rubin, Verena Stolcke, Joan Scott, Marta Lamas, Judith Butler y Jessica Benjamin, entre otros autores y autoras, muestra concepciones binarias, no binarias o sistémico relacionales sobre género, identidad de género y sistema de género, que utilizamos como marco conceptual para la elaboración del instrumento metodológico de nuestra investigación y la interpretación de las respuestas infantiles. Los estudios de género denuncian la lógica binaria, ofreciendo argumentos que visibilizan el hecho de que el ordenamiento en oposiciones y jerarquías no responde a un orden natural sino a largos procesos histórico-sociales, e implican posiciones de poder. Desde nuestro marco de investigación, este recorrido resulta no sólo imprescindible en tanto análisis histórico para conocer el problema epistemológico en juego, sino también ilustrativo de las diversas disciplinas y teorías involucradas en su estudio y discusión