Constant speed control of slider-crank mechanisms: a joint-task space hybrid control approach

In this paper, a constant speed control of slider-crank mechanisms for machine tools is proposed. A joint-task space hybrid controller based on a second-order sliding mode control and time-base generator was used to guarantee a constant speed trajectory tracking and a complete turn of the mechanism crank. A switching criterion was implemented in order to avoid the singularities located at the two extreme positions of the slider stroke. A trapezoidal speed profile with parabolic blends was designed directly over task space slider trajectory considering a constant cutting speed, the workpiece dimensions and the slider stroke length. Stability of the second-order sliding mode control was validated with the Lyapunov stability theory. Simulations were carried out to verify this approach

Efecto de cuatro compostas enzimáticas procedentes de la “planta frigorífico presidente Miguel Alemán Velasco”, Acayucan, Veracruz” en el cultivo del Frijol Ejotero

El presente trabajo analizó el efecto de compostas de origen enzimático procedentes de la “Planta Frigorífico Miguel Alemán”, de Acayucan, Veracruz, en el cultivo del frijol ejotero (Phaseolus vulgaris L.). Se compararon variables físicas y de rendimientos. Se utilizó un diseño de bloques al azar, con seis tratamientos y cuatro repeticiones. Cuatro de los tratamientos, T1 a T4, utilizaron fertilización con compostas (2,7 g por planta) obtenidas a partir de mezclas de contenido ruminal (CR), decomiso (D), sangre (S) y agua, procesadas con enzima Koprós® (E). Las combinaciones de los tratamientos fueron: T1: CR+D+S+E; T2: CR+S+E; T3: CR+D+H2O+E; T4: CR+H20+E. Los otros tratamientos fueron T5: NITROFOSKA® (granular, al pie 2,2 g) y T6: Testigo (sin fertilizante). El experimento se realizó en 24 parcelas demostrativas (parcela útil de 2,4m x 3m = 7,2m2, total de área de siembra: 172,80 m2). Se realizó un análisis de varianza y comparación de medias por el método de Tukey, utilizando el programa Statistica 7,0. En la comparación entre bloques, las variables Número de vainas por parcela (p=0,003), Largo de vainas (cm) (p=0,020) y Peso total por parcela (g) (p=0,008), presentaron diferencia significativa. El T2 (CR+S+E) presentó los mejores resultados para el número de vainas por planta (8,77) y por parcela (157), peso de la vaina (9,71 g) y rendimiento en grano por planta (34,33 g) (p≤0,008). El peso total por parcela fue mayor para el T5 con Nitrofoska® con 209,39 g (209,39 g)

Teoría sociológica contemporánea : un debate inconcluso

1 archivo PDF (155 páginas)"Uno de los propósitos de este conjunto de ensayos es plantear, a los futuros sociólogos y a los interesados en el tema, que la sociología no es una disciplina homogénea lidereada por una corriente teórica dominante. Es una disciplina que se mantiene en un equilibrio imperfecto, donde coexisten autores que comparten el intento de crear una teoría sintetizadora y; autores que parecen estar fuera de la "corriente teórica principal", que muestran la diversidad interpretativa y de objetos de investigación que se incluyen en el quehacer sociológico. Así, aparece frente a nosotros, una disciplina heterogénea y polémica, aunque no por eso, perdida en la diversidad inagotable.

A nationwide pilot study on breast cancer screening in Peru

"Introduction: A high prevalence of advanced breast cancer (BC) is a common scenario in Latin America. In Peru, the frequency of BC at Stages III/IV is ≈50% despite implementation of a programme for breast cancer screening (BCS) along the country. We carried out a study to assess the feasibility and develop an instrument to evaluate the knowledge, barriers and perception about BCS in a nationwide pilot study in Peru among candidates for BCS. Methods: We conducted a systematic review of 2,558 reports indexed in PubMed, Scopus, Web of Science, Medline-Ovid and EMBASE, regarding to our study theme. In total, 111 were selected and a 51-items survey was developed (eight items about sociodemographic characteristics). Patients were recruited in public hospitals or private clinics, in rural and urban areas of nine departments of Peru. Results: We surveyed 488 women from: Lima (150), Cajamarca (93), Ica (59), Arequipa (56), Loreto (48), Ancash (38), Junín (15), Puerto Maldonado (15) and Huancavelica (14); 27.9% of them were from rural areas. The mean of age was 53.3 years (standard deviation ± 9.1). Regarding education level, 29.8% had primary, 33.2% secondary and 37.0% higher education. In total, 28.7% of women did not know the term ‘mammogram’ and 47.1% reported never receiving a BCS (36.9% from urban and 73.5% from rural population). In women that underwent BCS, only 67% knew it is for healthy women. In total, 54.1% of patients had low levels of knowledge about risk factors for BC (i.e. 87.5% of women respond that injuries in the breast produce cancer). Cultural, economic and geographic barriers were significantly associated with having a mammogram where 56.9% of participants considered a cost ≤ 7 USD as appropriate. Mammogram was perceived as too painful for 54.9% of women. In addition, women with a self-perception of low-risk for BC and a fatalistic perception of cancer were less likely to have a BCS. Conclusion: We found that it is feasible to conduct a large-scale study in Peru. The results of this pilot study highlight an urgent need of extensive education and awareness about BCS in Peru.

Multiple Sclerosis and Its Relationship with Oxidative Stress, Glutathione Redox System, ATPase System, and Membrane Fluidity

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) with a focus on inflammation, demyelination, and damage to axons leading to neurological deficits. MS pathology is associated with excessive reactive oxygen species (ROS) and generation of reactive nitrogen species (RNS), causing oxidative/nitrosative stress. Deregulation of glutathione homeostasis and alterations in glutathione‐dependent enzymes are implicated in MS. Reactive oxygen species enhance both monocyte adhesion and migration across brain endothelial cells. In addition, ROS can activate the expression of the nuclear transcription factor‐kappa, which upregulates the expression of many genes involved in MS, such as tumor necrosis factor‐α and nitric oxide synthase, among others, leading to mitochondrial dysfunction and energy deficits that result in mitochondrial and cellular calcium overload. Loss of mitochondrial membrane potential can increase the release of cytochrome c, one pathway that leads to neuronal apoptosis. Clinical studies suggest that omega‐3 long‐chain polyunsaturated fatty acids (PUFAs) including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have anti‐inflammatory, antioxidant, and neuroprotective effects in MS and animal models of MS. Here, we review the relationship of oxidative stress, the glutathione redox system, the ATPase system, and membrane fluidity with the development of MS. In addition, we describe the main findings of a clinical trial conducted with relapsing‐remitting MS patients who received a diet supplemented with 4 g/day of fish oil or olive oil. The effects of PUFAs supplementation on the parameters indicated above are analyzed in this work

Primer consenso en leucemia linfocítica crónica de la agrupación mexicana para el estudio de la hematología: epidemiología, diagnóstico y tratamiento

La leucemia linfocítica crónica (LLC) es la leucemia crónica menos frecuente en México. En consideración a los avances recientes, a una mejor clasificación pronóstica y a la introducción de nuevas modalidades terapéuticas, la Agrupación Mexicana para el Estudio de la Hematología organizó el primer consenso mexicano en leucemia linfocítica crónica. Este consenso se llevó a cabo en Cancún, Quintana Roo, México, en Septiembre del 2007. Los objetivos de esta reunión fueron actualizar y compartir los conocimientos de la enfermedad entre los especialistas mexicanos, con el fin de mejorar el diagnóstico y el pronóstico de la LLC en México. En el artículo se discute los aspectos clínicos, diagnósticos y terapéuticos de la LLC

The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment

The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since July 2014. This paper describes the second data release from this phase, and the fourteenth from SDSS overall (making this, Data Release Fourteen or DR14). This release makes public data taken by SDSS-IV in its first two years of operation (July 2014-2016). Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey (eBOSS); the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data driven machine learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS website (www.sdss.org) has been updated for this release, and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020, and will be followed by SDSS-V.Comment: SDSS-IV collaboration alphabetical author data release paper. DR14 happened on 31st July 2017. 19 pages, 5 figures. Accepted by ApJS on 28th Nov 2017 (this is the "post-print" and "post-proofs" version; minor corrections only from v1, and most of errors found in proofs corrected

Territorios sustentables en contexto de pandemia

La obra ofrece trabajos que brindan un conocimiento científico sobre el impacto de la pandemia en la salud, la economía, el ambiente y los territorios y se plantean desafíos para hacer más sostenible la vida en las ciudades y en el campo para insertarse y poder competir a nivel global