The Puzzling Mutual Orbit of the Binary Trojan Asteroid (624) Hektor

Asteroids with satellites are natural laboratories to constrain the formation and evolution of our solar system. The binary Trojan asteroid (624) Hektor is the only known Trojan asteroid to possess a small satellite. Based on W.M. Keck adaptive optics observations, we found a unique and stable orbital solution, which is uncommon in comparison to the orbits of other large multiple asteroid systems studied so far. From lightcurve observations recorded since 1957, we showed that because the large Req=125-km primary may be made of two joint lobes, the moon could be ejecta of the low-velocity encounter, which formed the system. The inferred density of Hektor's system is comparable to the L5 Trojan doublet (617) Patroclus but due to their difference in physical properties and in reflectance spectra, both captured Trojan asteroids could have a different composition and origin.Comment: 13 pages, 3 figures, 2 table

Uso de Análisis de Covarianza (ANCOVA) en investigación científica

Key words: ANCOVA, auxiliary variable, error reduction, statisticsAbstract. The basics of the ANalisis of COVAriance (ANCOVA) are given. The objectives and the application of ANCOVA are laid out. Techniques for the estimation of contrasts and for the control and reduction of the degree of error are discussed. The application of a simple ANCOVA using real data is highlighted. The application of this technique in fixing the auxiliary variable in experimentation is emphasized.Palabras clave: ANCOVA, Estadística, reducción de error, variable auxiliarResumen. Se presentan las bases del ANálisis de COVArianza (ANCOVA). Se manejan los propósitos y la aplicación de este método estadístico. Se discuten las técnicas para la estimación de los contrastes, el control y la disminución del grado de error. Se presentan un ANCOVA simple mediante un ejemplo de datos reales. Se enfatiza el papel de esta técnica estadística en fijar el efecto de la variable auxiliar en el experimento

Childhood growth and development and DNA methylation age in mid-life

Background: In the first study of its kind, we examine the association between growth and development in early life and DNAm age biomarkers in mid-life. / Methods: Participants were from the Medical Research Council National Survey of Health and Development (n = 1376). Four DNAm age acceleration (AgeAccel) biomarkers were measured when participants were aged 53 years: AgeAccelHannum; AgeAccelHorvath; AgeAccelLevine; and AgeAccelGrim. Exposure variables included: relative weight gain (standardised residuals from models of current weight z-score on current height, and previous weight and height z-scores); and linear growth (standardised residuals from models of current height z-score on previous height and weight z-scores) during infancy (0–2 years, weight gain only), early childhood (2–4 years), middle childhood (4–7 years) and late childhood to adolescence (7–15 years); age at menarche; and pubertal stage for men at 14–15 years. The relationship between relative weight gain and linear growth and AgeAccel was investigated using conditional growth models. We replicated analyses from the late childhood to adolescence period and pubertal timing among 240 participants from The National Child and Development Study (NCDS). / Results: A 1SD increase in relative weight gain in late childhood to adolescence was associated with 0.50 years (95% CI 0.20, 0.79) higher AgeAccelGrim. Although the CI includes the null, the estimate was similar in NCDS [0.57 years (95% CI − 0.01, 1.16)] There was no strong evidence that relative weight gain and linear growth in childhood was associated with any other AgeAccel biomarker. There was no relationship between pubertal timing in men and AgeAccel biomarkers. Women who reached menarche ≥ 12 years had 1.20 years (95% CI 0.15, 2.24) higher AgeAccelGrim on average than women who reached menarche < 12 years; however, this was not replicated in NCDS and was not statistically significant after Bonferroni correction. / Conclusions: Our findings generally do not support an association between growth and AgeAccel biomarkers in mid-life. However, we found rapid weight gain during pubertal development, previously related to higher cardiovascular disease risk, to be associated with older AgeAccelGrim. Given this is an exploratory study, this finding requires replication

Uso de Análisis de Covarianza (ANCOVA) en investigación científica (Use of covariance analysis (ANCOVA) in scientific research)

Abstract. The basics of the ANalisis of COVAriance (ANCOVA) are given. The objectives and the application of ANCOVA are laid out. Techniques for the estimation of contrasts and for the control and reduction of the degree of error are discussed. The application of a simple ANCOVA using real data is highlighted. The application of this technique in fixing the auxiliary variable in experimentation is emphasized. Resumen. Se presentan las bases del ANálisis de COVArianza (ANCOVA). Se manejan los propósitos y la aplicación de este método estadístico. Se discuten las técnicas para la estimación de los contrastes, el control y la disminución del grado de error. Se presentan un ANCOVA simple mediante un ejemplo de datos reales. Se enfatiza el papel de esta técnica estadística en fijar el efecto de la variable auxiliar en el experimento

Diseños de distribucion libre (Free distribution designs)

Abstract. Science advances via discovery of patterns. Research in experimental sciences requires data gathering and hypothesis testing. The stochastic validity of the results is based entirely upon statistical analysis. Distribution free designs include the techniques of choice to be used in situations where assumptions on the type of the distribution are lacking. In this paper several distribution free models of common usage are discussed and an example for each model is provided. Resumen. La ciencia avanza via el descubrimiento de los patrones. La investigación en ciencias experimentales requiere colectar datos y probar hipótesis. La validez estocástica de los resultados depende totalmente de los análisis estadísticos. Los diseños de tipo distribución libre incluyen las técnicas de selección a utilizarse en condiciones en donde carecen supuestos sobre el de distribución de los datos. En este artículo se discuten varios modelos comunes de tipo de distribución libre y para cada caso se presenta un ejemplo práctico

Precisión de los índices estadísticas: Técnicas de jacknife & bootstrap

Key words: Bootstrap, jacknife, precision, statisticsAbstract. The processes involved in jacknife and bootstrap techniques are described. The relevance of these techniques as the means of estimating the degree of sampling precision is explained.Palabras claves: Bootstrap, estadística, jacknife, precisiónResumen. Se describen los procesos involucrados en las técnicas de jacknife y de bootstrap. Se explica la relevancia de estas dos técnicas como herramientas estadísticas para determinar el grado de la precisión de los datos muestrales

Spin models on random graphs with controlled topologies beyond degree constraints

We study Ising spin models on finitely connected random interaction graphs which are drawn from an ensemble in which not only the degree distribution $p(k)$ can be chosen arbitrarily, but which allows for further fine-tuning of the topology via preferential attachment of edges on the basis of an arbitrary function Q(k,k') of the degrees of the vertices involved. We solve these models using finite connectivity equilibrium replica theory, within the replica symmetric ansatz. In our ensemble of graphs, phase diagrams of the spin system are found to depend no longer only on the chosen degree distribution, but also on the choice made for Q(k,k'). The increased ability to control interaction topology in solvable models beyond prescribing only the degree distribution of the interaction graph enables a more accurate modeling of real-world interacting particle systems by spin systems on suitably defined random graphs.Comment: 21 pages, 4 figures, submitted to J Phys

Diseños experimentales e investigación científica

Key words: Design, experiment, research, scienceAbstract. The basics of the experimental designs are noted. Different features of common types of experimental designs such as the completely randomized design, the randomized block design, the Latin Square design, the split plot design and the factorial design are described. Each experimental design is illustrated by an example using real data. The application of experimental designs to the scientific research is discussed.Palabras claves: Ciencia, diseño, experimento, investigaciónResumen. Se describen los fundamentos de los diseños experimentales. Se explican las distintas características de los diseños experimentales del uso común, tales como el diseño completamente aleatorio, e diseño de bloques al azar, el diseño de cuadro latino, el diseño de parcelas divididas y el de factorial. Para cada diseño se presenta un ejemplo con los datos reales del campo. Se discute la aplicación de estos diseños en relación con la investigación científica

Precisión de los índices estadísticas: Técnicas de jacknife & bootstrap = Precision of statistical indices: Jacknife &bootstrap techniques.

Abstract. The processes involved in jacknife and bootstrap techniques are described. The relevance of these techniques as the means of estimating the degree of sampling precision is explained. Resumen. Se describen los procesos involucrados en las técnicas de jacknife y de bootstrap. Se explica la relevancia de estas dos técnicas como herramientas estadísticas para determinar el grado de la precisión de los datos muestrales

DNA methylation age and physical and cognitive ageing

Background: DNA methylation (DNAm) age acceleration (AgeAccel) has been shown to be predictive of all-cause mortality but it is unclear what functional aspect/s of ageing it captures. We examine associations between four measures of AgeAccel in adults aged 45-87 years and physical and cognitive performance and their age-related decline. / Methods: AgeAccelHannum, AgeAccelHorvath, AgeAccelPheno and AgeAccelGrim were calculated in the Medical Research Council National Survey of Health and Development (NSHD), National Child Development Study (NCDS) and TwinsUK. Three measures of physical (grip strength, chair rise speed and forced expiratory volume in one second[FEV1]) and two measures of cognitive (episodic memory and mental speed) performance were assessed. / Results: AgeAccelPheno and AgeAccelGrim, but not AgeAccelHannum and AgeAccelHorvath were related to performance in random effects meta-analyses (n=1388-1685). For example, a one year increase in AgeAccelPheno/AgeAccelGrim was associated with a 0.01ml[95%CI:0.01,0.02]/0.03ml[95%CI:0.01,0.05] lower mean FEV1. In NSHD, AgeAccelPheno and AgeAccelGrim at 53 years were associated with age-related decline in performance between 53 and 69 years as tested by linear mixed models (p<0.05). In a subset of NSHD participants(n=482), there was little evidence that change in any AgeAccel measure was associated with change in performance conditional on baseline performance. / Conclusions: We found little evidence to support associations between the first generation of DNAm-based biomarkers of ageing and age-related physical or cognitive performance in mid-life to early old age. However, there was evidence that the second generation biomarkers, AgeAccelPheno and AgeAccelGrim, could act as makers of an individual’s health-span as proposed