Introduction to string theory

El siguiente trabajo comienza, en su primer cap´ıtulo, tratando de enfatizar por qu´e se ha desarrollado la Teor´ıa de Cuerdas, explicando a qu´e cuestiones busca dar soluci´on, para ello se exponen una serie de ideas que giran entorno a la b´usqueda hist´orica de la unificaci´on en la f´ısica. Tras esta breve discusi´on, se repasa en el siguiente cap´ıtulo la cuerda cl´asica, dado que es el elemento del que se derivan e inspiran modelos m´as complejos que se tratan en sucesivos cap´ıtulos, precisamente se utiliza la misma para ilustrar c´omo se aplican los conceptos de acci´on y mec´anica lagrangiana al estudio de campos, y dejar as´ı patente la efectividad de estas herramientas. Tambi´en se derivan, a modo de ejemplo, una serie de expresiones correspondientes a campos complejos tales como la ecuaciones de Schr¨odinger y Dirac, con ello se persigue realzar el poder de la acci´on en la f´ısica matem´atica. En el cap´ıtulo 4 se estudia la part´ıcula puntual relativista, aqu´ı nos detenemos para repasar las bases de la relatividad especial, explicar las coordenadas del cono de luz y comprender la compactificaci´on como v´ıa para la posibilidad de dimensiones adicionales. Tras ello, se expone como estudiar la part´ıcula relativista empezando por la propuesta de una acci´on, desgranando a partir de la misma las ecuaciones de movimiento correspondientes. Posteriormente, en el cap´ıtulo 6, se utiliza este modelo para mostrar c´omo se realiza el proceso de cuantizaci´on de una teor´ıa no cu´antica. Para ello, se localizan las variables din´amicas del sistema y se transforman en los consiguientes operadores, se obtienen las relaciones de conmutaci´on, se define un hamiltoniano del que se pone a prueba su validez y se construyen el espacio de estados y la ecuaci´on de Schr¨odinger de la part´ıcula cu´antica libre. En paralelo, se comienza a estudiar la cuerda relativista. Mediante la hoja del mundo generada por la cuerda, que es una idea basada en la l´ınea del universo de la part´ıcula puntual, se justifica la acci´on de Nambu-Goto, esta acci´on pasa a ser la base la base de nuestro modelo. A partir de esta y de las condiciones de contorno que imponemos a los extremos de nuestra cuerda, derivamos su ecuaci´on de ondas, la forma de su energ´ıa potencial, obtenemos que los extremos de las cuerdas libres se mueven transversalmente a la velocidad de la luz y evaluamos las leyes de conservaci´on de la misma. Con esta informaci´on desarrollamos la soluci´on de la ecuaci´on de movimiento, que luego, sin llegar a demostrar expl´ı citamente, presentamos en el formalismo del cono de luz, definiendo en el proceso los modos transversales de Visasoro. Finalmente cuantizamos la cuerda relativista siguiendo un procedimiento similar al de la part´ıcula puntual, y discutimos como la primera se convierte en un oscilador arm´onico, cuyos modos de vibraci´on marcan la diferencia con segunda. Por ´ultimo presentamos, sin ´animo de demostrar expl´ıcitamente, como la Teor´ıa de Cuerdas bos´onica predice la existencia de hasta 26 dimensiones, es decir, 22 dimensiones adicionales

Prospective Exploratory Analysis of Angiogenic Biomarkers in Peripheral Blood in Advanced NSCLC Patients Treated With Bevacizumab Plus Chemotherapy: The ANGIOMET Study

Finding angiogenic prognostic markers in advanced non-small-cell lung cancer is still an unmet medical need. We explored a set of genetic variants in the VEGF-pathway as potential biomarkers to predict clinical outcomes of patients with non-small-cell lung cancer treated with chemotherapy plus bevacizumab. We prospectively analyzed the relationship between VEGF-pathway components with both pathological and prognostic variables in response to chemotherapy plus bevacizumab in 168 patients with non-squamous non-small-cell lung cancer. Circulating levels of VEGF and VEGFR2 and expression of specific endothelial surface markers and single-nucleotide polymorphisms in VEGF-pathway genes were analyzed. The primary clinical endpoint was progression-free survival. Secondary endpoints included overall survival and objective tumor response. VEGFR-1 rs9582036 variants AA/AC were associated with increased progression-free survival (p = 0.012 and p = 0.035, respectively), and with improved overall survival (p = 0.019) with respect to CC allele. Patients with VEGF-A rs3025039 harboring allele TT had also reduced mortality risk (p = 0.049) compared with the CC allele. The VEGF-A rs833061 variant was found to be related with response to treatment, with 61.1% of patients harboring the CC allele achieving partial treatment response. High pre-treatment circulating levels of VEGF-A were associated with shorter progression-free survival (p = 0.036). In conclusion, in this prospective study, genetic variants in VEGFR-1 and VEGF-A and plasma levels of VEGF-A were associated with clinical benefit, progression-free survival, or overall survival in a cohort of advanced non-squamous non-small-cell lung cancer patients receiving chemotherapy plus antiangiogenic therapy

Performance of standardised colposcopy to detect cervical precancer and cancer for triage of women testing positive for human papillomavirus : results from the ESTAMPA multicentric screening study

Correspondence to: Dr Joan Valls, Early Detection, Prevention and Infections Branch, International Agency for Research on Cancer, Lyon 69366, France. [email protected]. Colposcopy, currently included in WHO recommendations as an option to triage human papillomavirus (HPV)-positive women, remains as the reference standard to guide both biopsy for confirmation of cervical precancer and cancer and treatment approaches. We aim to evaluate the performance of colposcopy to detect cervical precancer and cancer for triage in HPV-positive women. Methods. This cross-sectional, multicentric screening study was conducted at 12 centres (including primary and secondary care centres, hospitals, laboratories, and universities) in Latin America (Argentina, Bolivia, Colombia, Costa Rica, Honduras, Mexico, Paraguay, Peru, and Uruguay). Eligible women were aged 30–64 years, sexually active, did not have a history of cervical cancer or treatment for cervical precancer or a hysterectomy, and were not planning to move outside of the study area. Women were screened with HPV DNA testing and cytology. HPV-positive women were referred to colposcopy using a standardised protocol, including biopsy collection of observed lesions, endocervical sampling for transformation zone (TZ) type 3, and treatment as needed. Women with initial normal colposcopy or no high-grade cervical lesions on histology (less than cervical intraepithelial neoplasia [CIN] grade 2) were recalled after 18 months for another HPV test to complete disease ascertainment; HPV-positive women were referred for a second colposcopy with biopsy and treatment as needed. Diagnostic accuracy of colposcopy was assessed by considering a positive test result when the colposcopic impression at the initial colposcopy was positive minor, positive major, or suspected cancer, and was considered negative otherwise. The main study outcome was histologically confirmed CIN3+ (defined as grade 3 or worse) detected at the initial visit or 18-month visit. Findings. Between Dec 12, 2012, and Dec 3, 2021, 42 502 women were recruited, and 5985 (14·1%) tested positive for HPV. 4499 participants with complete disease ascertainment and follow-up were included in the analysis, with a median age of 40·6 years (IQR 34·7–49·9). CIN3+ was detected in 669 (14·9%) of 4499 women at the initial visit or 18-month visit (3530 [78·5%] negative or CIN1, 300 [6·7%] CIN2, 616 [13·7%] CIN3, and 53 [1·2%] cancers). Sensitivity was 91·2% (95% CI 88·9–93·2) for CIN3+, whereas specificity was 50·1% (48·5–51·8) for less than CIN2 and 47·1% (45·5–48·7) for less than CIN3. Sensitivity for CIN3+ significantly decreased in older women (93·5% [95% CI 91·3–95·3] in those aged 30–49 years vs 77·6% [68·6–85·0] in those aged 50–65 years; p<0·0001), whereas specificity for less than CIN2 significantly increased (45·7% [43·8–47·6] vs 61·8% [58·7–64·8]; p<0·0001). Sensitivity for CIN3+ was also significantly lower in women with negative cytology than in those with abnormal cytology (p<0·0001). Interpretation. Colposcopy is accurate for CIN3+ detection in HPV-positive women. These results reflect ESTAMPA efforts in an 18-month follow-up strategy to maximise disease detection with an internationally validated clinical management protocol and regular training, including quality improvement practices. We showed that colposcopy can be optimised with proper standardisation to be used as triage in HPV-positive women.Consejo Nacional de Ciencia y TecnologíaPrograma Paraguayo para el Desarrollo de la Ciencia y Tecnología. Proyectos de investigación y desarrollo14-INV-036PINV18-25

Multicentric study of cervical cancer screening with human papillomavirus testing and assessment of triage methods in Latin America : the ESTAMPA screening study protocol

Q1Q1Introduction Human papillomavirus (HPV) testing is replacing cytology in primary screening. Its limited specificity demands using a second (triage) test to better identify women at high-risk of cervical disease. Cytology represents the immediate triage but its low sensitivity might hamper HPV testing sensitivity, particularly in low-income and middle-income countries (LMICs), where cytology performance has been suboptimal. The ESTAMPA (EStudio multicéntrico de TAMizaje y triaje de cáncer de cuello uterino con pruebas del virus del PApiloma humano; Spanish acronym) study will: (1) evaluate the performance of different triage techniques to detect cervical precancer and (2) inform on how to implement HPV-based screening programmes in LMIC. Methods and analysis Women aged 30–64 years are screened with HPV testing and Pap across 12 study centres in Latin America. Screened positives have colposcopy with biopsy and treatment of lesions. Women with no evident disease are recalled 18 months later for another HPV test; those HPV-positive undergo colposcopy with biopsy and treatment as needed. Biological specimens are collected in different visits for triage testing, which is not used for clinical management. The study outcome is histological high-grade squamous intraepithelial or worse lesions (HSIL+) under the lower anogenital squamous terminology. About 50 000 women will be screened and 500 HSIL+ cases detected (at initial and 18 months screening). Performance measures (sensitivity, specificity and predictive values) of triage techniques to detect HSIL+ will be estimated and compared with adjustment by age and study centre. Ethics and dissemination The study protocol has been approved by the Ethics Committee of the International Agency for Research on Cancer (IARC), of the Pan American Health Organisation (PAHO) and by those in each participating centre. A Data and Safety Monitoring Board (DSMB) has been established to monitor progress of the study, assure participant safety, advice on scientific conduct and analysis and suggest protocol improvements. Study findings will be published in peer-reviewed journals and presented at scientific meetings. Trial registration number NCT01881659Revista Internacional - Indexad

El docente de tercer nivel en las ciencias de la salud. Contexto ecuatoriano

Resumen: Introducción: La superación permanente del graduado universitario constituye una dirección de trabajo de la educación superior ecuatoriana. En la misma concurren procesos formativos y de desarrollo, no solo de enseñanza aprendizaje, sino también de investigación, innovación, creación, transferencia y otros, articulados armónicamente en una propuesta docente-educativa pertinente a este nivel. Profundizar en el rol del profesor que imparte docencia en la enseñanza de tercer nivel constituyó el objetivo de este trabajo, para lo cual se realizó una investigación descriptiva, con un enfoque cualitativo, durante el período comprendido entre abril-agosto de 2015. La población estuvo constituida por los reglamentos y documentos rectores a tener en cuenta en la formación universitaria. Se emplearon métodos lógico-práctico, inductivo-deductivo y analítico-sintético. Resultados: El docente es concebido como promotor del análisis reflexivo, inductor de cambios, activador de la búsqueda del saber, suscitador de la discusión científica, generador de hipótesis, frente a un grupo estudiantil que piensa, crea, transforma, organiza y estructura conocimientos en un sistema personal, dinámico y contextual, cada vez más plural y diverso. Conclusiones: La preparación permanente e integral del docente universitario constituye un eje fundamental para la formación del estudiante y la transformación de la sociedad. Se sustenta en adquisición por estos de habilidades del lenguaje, la comunicación, el pensamiento crítico, ético y del conocimiento de un idioma extranjero y de las TIC, lo que les permitirá integrar las funciones sustantivas de la universidad, guiadas estas por la investigación. Deben ser poseedores de valores y cualidades humanas que contribuyan al alcance del buen vivir por la población ecuatoriana, del dominio disciplinar, profesional e investigador, en un marco donde la interculturalidad, el diálogo de saberes, la unidad en la multiplicidad, el respeto a la diversidad y la convivencia armónica con la naturaleza, constituyen elementos componentes de la formación de tercer nivel. Abstract: Introduction: The constant improvement of university graduate courses is a work instigated by the Ecuadorian Higher Education. These include training and development processes, not only of learning, but also for research, innovation, development, transfer and others, harmoniously coordinated into an appropriate teacher-education model at this level. The aim of this work is to detail the role of the teacher who teaches in tertiary education, by conducting a study, with a qualitative approach, during the period April to August 2015. The population consisted of the regulations and regulatory documents to be considered in university education. Logical and practical, and inductive. and analytical-synthetic methods were used. Results: The teacher is conceived as a promoter of reflective analysis, instigator of changes, activator of the search for knowledge, trigger the search for knowledge, stimulator of scientific discussion, hypothesis generator, faced with a group of students that thinks, creates, transforms, organises, and structures knowledge in an increasingly pluralistic and diverse, in a personal and dynamic and contextual system. Conclusions: Permanent and comprehensive training of university teachers is fundamental to student training and the transformation of society. It is based on these acquisition of language skills, communication, critical, ethical and knowledge of a foreign language and information and communications technologies, enabling them to integrate the basic functions of the university, all guided by research. They must be holders of values and human qualities that contribute to the scope of good living for the Ecuadorian population, the domain discipline, professional and research, in a context where the intercultural dialogue of knowledge, unity in multiplicity, respect for diversity and harmonious co-existence with nature, constitute component elements of tertiary education. Palabras clave: Educación superior, Ciencias de la salud, Tercer nivel, Formación docente, Ecuador, Keywords: Higher education, Health sciences, Third level, Teacher training, Ecuado

Global diversity and distribution of aerobic anoxygenic phototrophs in the tropical and subtropical oceans

The aerobic anoxygenic phototrophic (AAP) bacteria are common in most marine environments but their global diversity and biogeography remain poorly characterized. Here, we analyzed AAP communities across 113 globally-distributed surface ocean stations sampled during the Malaspina Expedition in the tropical and subtropical ocean. By means of amplicon sequencing of the pufM gene, a genetic marker for this functional group, we show that AAP communities along the surface ocean were mainly composed of members of the Halieaceae (Gammaproteobacteria), which were adapted to a large range of environmental conditions, and of different clades of the Alphaproteobacteria, which seemed to dominate under particular circumstances, such as in the oligotrophic gyres. AAP taxa were spatially structured within each of the studied oceans, with communities from adjacent stations sharing more taxonomic similarities. AAP communities were composed of a large pool of rare members and several habitat specialists. When compared to the surface ocean prokaryotic and picoeukaryotic communities, it appears that AAP communities display an idiosyncratic global biogeographical pattern, dominated by selection processes and less influenced by dispersal limitation. Our study contributes to the understanding of how AAP communities are distributed in the horizontal dimension and the mechanisms underlying their distribution across the global surface ocean

La solidaridad, valor innegable del ser humano

El 16 de abril de 2016 Ecuador sufrió uno de los desastres naturales más grandes de la historia de este país; un terremoto de 7,8 grados sacudió al país dejando una enorme estela de muertos, heridos, daños económicos, sociales y psicológicos. La ayuda nacional e internacional no se hizo esperar. En este trabajo mostramos, de forma gráfica, como un grupo de trabajadores de la Universidad Nacional de Chimborazo, mediante una brigada de apoyo, brindan su aporte solidario en áreas afectadas por el sismo a solo pocos días de haber sucedido esta tragedia

Prevalencia de parasitosis intestinal y condicionantes de la salud en menores de 12 años con diarrea aguda atendidos en consulta externa, comunidad de Jamalteca, Comayagua, Honduras

Introduction: Acute diarrhea consists of an increase in the number of stools and / or a decrease in their consistency, of rapid onset. The most frequent parasite cause is by geohelminths. Objective: To determine the most frequent and determinant parasitic agents of health in children under 12 years of age with acute diarrhea in the community of Jamalteca in the department of Comayagua. Material and method:Quantitative study. With a universe of 80 children based on the prevalence of the disease of the previous month, a sample of 68 children was obtained, with a confidence level of 97%. Data collection by means of the implementation of a questionnaire, in addition, the general examination of feces was done to each participant and samples of drinking water of the houses were studied. Results: 55.8% had 1-5 years of age, with female predominance (54.4%). 17.6% of the parents finished secondary education, where, 86.7% are poor. The predominant parasite was Ascaris lumbricoides in 17.6% of the samples, followed by Entamoeba coli (16.1%), Chilomastis Meslini and Trichuris trichuria (both 13.2%). Samples of boiled and potable water (19.1%) were positive with colonies of coliforms and colonies of E. coli; Bottled water (33.3%) presented colony of coliforms. As hygienic measures 30.8% washes the breath before consumption, likewise, 13.2% of children are washing their hands before eating and 7.3% of children are washing their hands after going to the bathroom. Conclusion: Intestinal parasitism is the main cause of infectious diarrhea,where Ascaris lumbricoides is the referent. The determinants of health in the studied families are deplorable, presenting inadequate socioeconomic conditions. In addition, hygienic measures in food handling and water consumption demonstrated sources of intestinal infections with epidemic potential.Introducción: La diarrea aguda consiste en un aumento en el número de deposiciones y/o una disminución en su consistencia, de instauración rápida. La causa parasitaria más frecuente es por geohelmintos. Objetivo: Determinar los agentes parasitarios más frecuentes y determinantes de la salud en niños (as) menores de 12 años con diarrea aguda, en la comunidad de Jamalteca del departamento de Comayagua. Material y método: Estudio cuantitativo. Con un universo de 80 niños en base a la prevalencia de la enfermedad del mes previo, se obtuvo una muestra de 68 niños, con nivel de confianza de 97%. La recolección de datos fue mediante la implementación de un cuestionario, además, se realizó examen general de heces a cada participante, se estudiaron muestras de agua de consumo. Resultados: El 55.8% tenían de 1-5 años, con predominio del sexo femenino (54.4%). El 17.6% de los padres terminó la educación secundaria, donde, el 86.7% son pobres. El parasito predominante fue Ascaris lumbricoides (17.6%) de las muestras, seguido de Entamoeba coli (16.1%), Chilomastis Meslini y Trichuris trichuria (ambos 13.2%). Las muestras de agua hervida y potable (19.1%) resultaron positivas con colonias de coliformes y colonias de E. coli; El agua embotellada (33.3%) presentó colonia de coliformes. Como medidas higiénicas el 30.8% lava los alientos antes de su consumo, asimismo, el 13.2% de los niños se lava las manos antes de comer y el 7.3% de los niños se lava las manos después de ir al baño. Conclusión: El parasitismo intestinal es la principal causa de diarreas infecciosas, donde, Ascaris lumbricoides es el referente. Las determinantes de la salud en las familias estudiadas son deplorables presentando condiciones socioeconómicas inadecuadas, además, las medidas higiénicas en el manejo de los alimentos y el consumo de agua demostraron ser fuentes de infecciones intestinales con potencial epidémico

Exploring Microdiversity in Novel Kordia sp. (Bacteroidetes) with Proteorhodopsin from the Tropical Indian Ocean via Single Amplified Genomes

Marine Bacteroidetes constitute a very abundant bacterioplankton group in the oceans that plays a key role in recycling particulate organic matter and includes several photoheterotrophic members containing proteorhodopsin. Relatively few marine Bacteroidetes species have been described and, moreover, they correspond to cultured isolates, which in most cases do not represent the actual abundant or ecologically relevant microorganisms in the natural environment. In this study, we explored the microdiversity of 98 Single Amplified Genomes (SAGs) retrieved from the surface waters of the underexplored North Indian Ocean, whose most closely related isolate is Kordia algicida OT-1. Using Multi Locus Sequencing Analysis (MLSA) we found no microdiversity in the tested conserved phylogenetic markers (16S rRNA and 23S rRNA genes), the fast-evolving Internal Transcribed Spacer and the functional markers proteorhodopsin and the beta-subunit of RNA polymerase. Furthermore, we carried out a Fragment Recruitment Analysis (FRA) with marine metagenomes to learn about the distribution and dynamics of this microorganism in different locations, depths and size fractions. This analysis indicated that this taxon belongs to the rare biosphere, showing its highest abundance after upwelling-induced phytoplankton blooms and sinking to the deep ocean with large organic matter particles. This uncultured Kordia lineage likely represents a novel Kordia species (Kordia sp. CFSAG39SUR) that contains the proteorhodopsin gene and has a widespread spatial and vertical distribution. The combination of SAGs and MLSA makes a valuable approach to infer putative ecological roles of uncultured abundant microorganisms.ISSN:1664-302