Uniform asymptotics for robust location estimates when the scale is unknown

Most asymptotic results for robust estimates rely on regularity conditions that are difficult to verify in practice. Moreover, these results apply to fixed distribution functions. In the robustness context the distribution of the data remains largely unspecified and hence results that hold uniformly over a set of possible distribution functions are of theoretical and practical interest. Also, it is desirable to be able to determine the size of the set of distribution functions where the uniform properties hold. In this paper we study the problem of obtaining verifiable regularity conditions that suffice to yield uniform consistency and uniform asymptotic normality for location robust estimates when the scale of the errors is unknown. We study M-location estimates calculated with an S-scale and we obtain uniform asymptotic results over contamination neighborhoods. Moreover, we show how to calculate the maximum size of the contamination neighborhoods where these uniform results hold. There is a trade-off between the size of these neighborhoods and the breakdown point of the scale estimate.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Statistics (http://www.imstat.org/aos/) at http://dx.doi.org/10.1214/00905360400000054

Uniform asymptotics for robust location estimates when the scale is unknown

Most asymptotic results for robust estimates rely on regularity conditions that are difficult to verify and that real data sets rarely satisfy. Moreover, these results apply to fixed distribution functions. In the robustness context the distribution of the data remains largely unspecified and hence results that hold uniformly over a set of possible distribution functions are of theoretical and practical interest. In this paper we study the problem of obtaining verifiable and realistic conditions that suffice to obtain uniform consistency and uniform asymptotic normality for location robust estimates when the scale of the errors is unknown. We study M-location estimates calculated withan S-scale and we obtain uniform asymptotic results over contamination neighbourhoods. There is a trade-off between the size of these neighbourhoods and the breakdown point of the scale estimate. We also show how to calculate the maximum size of the contamination neighbourhoods where these uniform results hold.

Improving ocean-glider's payload with a new generation of spectrophotometric PH sensor

Ocean gliders have clearly become nowadays useful autonomous platforms addressed to measure a wide range of seawater parameters in a more sustainable and efficient way. This new ocean monitoring approach has implied the need to develop smaller, faster and more efficient sensors without reducing key features like accuracy, resolution, time-response, among others, in order to fit the glider operational capabilities. This work is aiming to present the latest development stages of a new spectrophotometric pH sensor, its integration process into a Wave Glider SV3 platform and the preliminary results derived from an offshore mission performed in subtropical waters between the Canary Islands and Cape Verde archipelagos.Peer Reviewe

Embarazo después de cirugía bariátrica

ResumenLa obesidad ha adquirido características de pandemia, extendida a todo el orbe, alcanzando a diferentes etnias, edades y sin diferencias de género. Las mujeres embarazadas constituyen un grupo particularmente vulnerable a los trastornos nutricionales y la obesidad representa un importante factor de riesgo para la madre y el feto. Múltiples estrategias se han desarrollado con el objeto de disminuir la prevalencia de los trastornos alimenticios en exceso y aminorar sus efectos, con resultados limitados. En los últimos años la cirugía bariátrica con sus distintas modalidades se ha constituido en una alternativa para el tratamiento de la mujer obesa y los resultados reportados señalan significativas bajas de peso y un mejor control de comorbilidades asociadas. La aparición de un población cada vez más numerosa de mujeres sometidas a cirugía bariátrica que se embarazan, ha llevado a desarrollar estrategias de control de esos embarazos, con recomendaciones nutricionales y vigilancia estricta de la madre y el feto, por equipos multidisciplinarios. Respecto de los resultados de embarazos posteriores a cirugía bariátrica, se ha reportado un gran número de publicaciones comunicando la experiencia de distintos grupos, utilizando variados diseños de estudio, haciendo referencia a distintas técnicas quirúrgicas con diferentes grupos control y tiempos de seguimiento, con resultados heterogéneos y a veces inconsistentes. Si bien se observa una tendencia a la disminución de desórdenes hipertensivos, diabetes gestacional y macrosomía fetal, con aumento de la incidencia de recién nacidos pequeños para la edad gestacional y parto prematuro, se requiere de nuevos estudios que permitan con mayor confiabilidad establecer los resultados de esos embarazos y desarrollar recomendaciones a lo equipos médicos, a los pacientes y sus familias.SummaryObesity has become pandemic characteristics, extended to the whole world, reaching all ethnicities, ages without gender differences. Pregnant women are particularly vulnerable to nutritional disorders and obesity is a major risk factor for mother and fetus. Multiple strategies have been developed in order to reduce the prevalence of eating disorders in excess and reduce its effects, with limited results. In recent years, bariatric surgery with its various forms has become an alternative for the treatment of obese women and the reported results indicate significant lower weight and better control of comorbidities. The emergence of an increasingly large cask of women undergoing surgery who become pregnant population, has led to develop control strategies of these pregnancies, nutritional recommendations and close monitoring of the mother and fetus by multidisciplinary teams. Regarding the results of pregnancies after bariatric surgery, there have been a large number of publications communicating the experience of different groups, using different study designs, referring to different surgical techniques, with different control groups and followup times, with results heterogeneous and sometimes inconsistent. While a decreasing trend of hypertensive disorders, gestational diabetes and fetal macrosomia, with increased incidence of infants small for gestational age and preterm birth, it appears it requires new studies to more reliably establish the results of these pregnancies and develop recommendations to medical equipment, patients and their families

Magnetic field detection in the B2Vn star HR 7355

The B2Vn star HR 7355 is found to be a He-rich magnetic star. Spectropolarimetric data were obtained with FORS1 at UT2 on Paranal observatory to measure the disk-averaged longitudinal magnetic field at various phases of the presumed 0.52 d cycle. A variable magnetic field with strengths between B_z = -2200 and +3200G was found, with confidence limits of 100 to 130G. The field topology is that of an oblique dipole, while the star itself is seen about equator-on. In the intensity spectra the HeI-lines show the typical equivalent width variability of He-strong stars, usually attributed to surface abundance spots. The amplitudes of the equivalent width variability of the HeI lines are extraordinarily strong compared to other cases. These results not only put HR 7355 unambiguously among the early-type magnetic stars, but confirm its outstanding nature: With v sin i = 320 km/s the parameter space in which He-strong stars are known to exist has doubled in terms of rotational velocity.Comment: 6 pages, 5 figures, 1 Table. Accepted for publication in MNRAS Letter

The (B0+?)+O6 system FN CMa: A case for tidal-pulsational interaction?

FN CMa is visually double with a separation of about 0.6arcsec. Sixty high-cadence VLT/UVES spectra permit the A and B components to be disentangled, as the relative contribution of each star to the total light entering the spectrograph fluctuates between exposures due to changes in seeing. Component A exhibits rapid line-profile variations, leading us to attribute the photometric variability seen by HIPPARCOS (with a derived P=0.08866d) to this component. From a total of 122 archival and new echelle spectra it is shown that component A is an SB1 binary with an orbital period of 117.55 days. The eccentricity of 0.6 may result in tidal modulation of the pulsation(s) of component Aa.Comment: 2 pages, 1 figure, IAUS 272 - Active OB Stars: Structure, Evolution, Mass Loss and Critical Limit

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

Machine characterization and benchmark performance prediction

From runs of standard benchmarks or benchmark suites, it is not possible to characterize the machine nor to predict the run time of other benchmarks which have not been run. A new approach to benchmarking and machine characterization is reported. The creation and use of a machine analyzer is described, which measures the performance of a given machine on FORTRAN source language constructs. The machine analyzer yields a set of parameters which characterize the machine and spotlight its strong and weak points. Also described is a program analyzer, which analyzes FORTRAN programs and determines the frequency of execution of each of the same set of source language operations. It is then shown that by combining a machine characterization and a program characterization, we are able to predict with good accuracy the run time of a given benchmark on a given machine. Characterizations are provided for the Cray-X-MP/48, Cyber 205, IBM 3090/200, Amdahl 5840, Convex C-1, VAX 8600, VAX 11/785, VAX 11/780, SUN 3/50, and IBM RT-PC/125, and for the following benchmark programs or suites: Los Alamos (BMK8A1), Baskett, Linpack, Livermore Loops, Madelbrot Set, NAS Kernels, Shell Sort, Smith, Whetstone and Sieve of Erathostenes