Enseñanza media

Generalmente se ha hecho coincidir el punto de partida de la ciencia moderna con la aparición del método experimental (siglos XVI y XVII) Todo el saber de la antigüedad era empírico. Arquímedes es la excepción al realizar experiencias e interpretar los hechos de forma experimental. La Edad Media no fue un periodo totalmente oscuro pues se ha demostrado que aquí están las bases de la ciencia moderna. Si la ciencia no llega a la madurez en este periodo es como demuestra más interés por la cualidad que por la cantidad. El paso de lo cualitativo a lo cuantitativo es una de las características más importantes de los siglos XVI y XVII.. los progresos científicos iniciados en este último siglo siguen dos caminos el de Galileo-Newton, caracterizado por el descubrimiento de gran número de fenómenos y el invento de aparatos destinados a ponerlos en práctica. El otro caracterizado por la introducción de magnitudes extensivas: masa, volumen, energía. Por ambos caminos se coordinan los resultados, se enuncian leyes y sus fórmulas. Así, se edifica la teoría. Pero el desarrollo de la teoría exige el concurso de las matemáticas, física y en menor medida de la química. Por eso se explican los grandes trabajos teóricos del siglo XVIII. Los dos caminos utilizados para la construcción de la ciencia son el deductivo, (utilizado por la química) y el inductivo (propio de la física) si bien quedan muchos problemas por resolver, han sido muchas las conquistas realizadas en los últimos años. En realidad, las distintas ramas de la ciencia están íntimamente relacionadas, de tal forma que el avance de una de ellas supone un mejor conocimiento de las demás.Ministerio Educación CIDEBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín, 5 - 3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]

Tom\ue1s Quintero Guerra y Ram\uf3n Trujillo Torres, los primeros canarios que publican en los anales de la Sociedad de F\uedsica y Qu\uedmica trabajos de investigaci\uf3n realizados en la Universidad de La Laguna

Volume: 20Start Page: 145End Page: 17

Exploring chromium (VI) dioxodihalides chemistry: is density functional theory the most suitable tool?

A comparative systematic study of the CrO2F2 compound has been performed using different conventional ab initio methodologies and density functional procedures. Two points have been analyzed: first, the accuracy of results yielded by each method under study, and second, the computational cost required to reach such results. Weighing up both aspects, density functional theory has been found to be more appropriate than the Hartree-Fock (HF) and the analyzed post-HF methods. Hence, the structural characterization and spectroscopic elucidation of the full CrO2X2 series (X=F,Cl,Br,I) has been done at this level of theory. Emphasis has been given to the unknown CrO2I2 species, and specially to the UV/visible spectra of all four compounds. Furthermore, a topological analysis in terms of charge density distributions has revealed why the valence shell electron pair repulsion model fails in predicting the molecular shape of such CrO2X2 complexe

Estructura del N-[2-(3-etil-indol)-piridoxaldimina]

Volume: 11Start Page: 305End Page: 31

Clinical Presentation and Short- and Long-term Outcomes in Patients With Isolated Distal Deep Vein Thrombosis vs Proximal Deep Vein Thrombosis in the RIETE Registry

International audienceImportance: Insufficient data exist about the clinical presentation, short-term, and long-term outcomes of patients with isolated distal deep vein thrombosis (IDDVT), that is, thrombosis in infrapopliteal veins without proximal extension or pulmonary embolism (PE).Objective: To determine the clinical characteristics, short-term, and 1-year outcomes in patients with IDDVT and to compare the outcomes in unadjusted and multivariable adjusted analyses with patients who had proximal DVT.Design, setting, and participants: This was a multicenter, international cohort study in participating sites of the Registro Informatizado Enfermedad Tromboembólica (RIETE) registry conducted from March 1, 2001, through February 28, 2021. Patients included in this study had IDDVT. Patients with proximal DVT were identified for comparison. Patients were excluded if they had a history of asymptomatic DVT, upper-extremity DVT, coexisting PE, or COVID-19 infection.Main outcomes and measures: Primary outcomes were 90-day and 1-year mortality, 1-year major bleeding, and 1-year venous thromboembolism (VTE) deterioration, which was defined as subsequent development of proximal DVT or PE.Results: A total of 33 897 patients were identified with isolated DVT (without concomitant PE); 5938 (17.5%) had IDDVT (mean [SD] age, 61 [17] years; 2975 male patients [50.1%]), and 27 959 (82.5%) had proximal DVT (mean [SD] age, 65 [18] years; 14 315 male patients [51.2%]). Compared with individuals with proximal DVT, those with IDDVT had a lower comorbidity burden but were more likely to have had recent surgery or to have received hormonal therapy. Patients with IDDVT had lower risk of 90-day mortality compared with those with proximal DVT (odds ratio [OR], 0.47; 95% CI, 0.40-0.55). Findings were similar in 1-year unadjusted analyses (hazard ratio [HR], 0.52; 95% CI, 0.46-0.59) and adjusted analyses (HR, 0.72; 95% CI, 0.64-0.82). Patients with IDDVT had a lower 1-year hazard of VTE deterioration (HR, 0.83; 95% CI, 0.69-0.99). In 1-year adjusted analyses of patients without an adverse event within the first 3 months, IDDVT was associated with lower risk of VTE deterioration (adjusted HR, 0.48; 95% CI, 0.24-0.97). By 1-year follow-up, symptoms or signs of postthrombotic syndrome were less common in patients with IDDVT (47.6% vs 60.5%).Conclusions and relevance: Results of this cohort study suggest that patients with IDDVT had a less ominous prognosis compared with patients with proximal DVT. Such differences were likely multifactorial, including the differences in demographics, risk factors, comorbidities, particularly for all-cause mortality, and a potential association of thrombus location with VTE deterioration and postthrombotic syndrome. Randomized clinical trials are needed to assess the optimal long-term management of IDDVT