Comparison of different fractal dimension measuring algorithms for RE-TM M-O films

Noise in magneto-optical recording devices is discussed. In general, it appears that either the divider technique or amplitude spectrum technique may be used interchangeably to measure the fractal dimension (D) in the domain wall structure of ideal images. However, some caveats must be observed for best results. The divider technique is attractive for its simplicity and relatively modest computation requirements. However, it is sensitive to noise, in that noise pixels that touch the domain boundary are interpreted as being part of the boundary, skewing the measurement. Also, it is not useful in measuring nucleation-dominated films or domains that have significant amounts of structure within the interior of the domain wall. The amplitude spectrum method is more complex, and less intuitive than the divider method, and somewhat more expensive to implement computationally. However, since the camera noise tends to be white, the noise can be avoided in the measurement of D by avoiding that portion of the curve that is flat (due to the white noise) when the least squares line is fit to the plot. Also, many image processing software packages include a Fast Fourier Transformation (FFT) facility, while the user will most likely have to write his own edge extraction routine for the divider method. The amplitude spectrum method is a true two dimensional technique that probes the interior of the domain wall, and in fact, can measure arbitrary clusters of domains. It can also be used to measure grey-level images, further reducing processing steps needed to threshold the image

Analysis of stress intensity factors and T-stress to control crack propagation for kerf-less spalling of single crystal silicon foils

International audienceMonocrystalline silicon (called mono silicon) is extensively used in the electronic and solar photovoltaic industries. During the last decade, many new manufacturing processes have been developed to improve solar cells' efficiency while reducing their cost of production. This paper focuses on a kerf-less technique based on the controlled fracture of silicon foils by depositing an adherent stress-inducing layer on {hkl} cleavage plans. A finite element model (FEM) is defined to study the stress intensity factors (SIFs) associated with a pre-crack located at a certain depth from the interface between the silicon substrate and the stress-inducing layer. A parametric study elucidates the dependence of the crack propagation direction on process variables including thickness of the stress-inducing layer, silicon substrate thickness, and pre-crack depth. The use of stress intensity factors and the T-stress characterize the crack propagation. These results are essential for efficient control of this kerf-less spalling process

Anatomy of flower and fruit of Vassobia breviflora (Solanaceae) in the south of the southern Yungas (Argentina)

Solanaceae es una familia con aproximadamente 2400 especies de distribución cosmopolita. Vassobia breviflora es la única especie del género presente en Argentina. El objetivo de este trabajo fue revisar y caracterizar la anatomía de la flor y fruto de V. breviflora a partir de muestras recolectadas en poblaciones de las Yungas del noroeste argentino. Se aplicaron técnicas anatómicas convencionales. Los resultados mostraron que la mayoría de las estructuras de la flor, el fruto y la semilla no difirieron de lo previamente reportado respecto de la organización estructural descripta para otras especies de Solanaceae. No obstante, por primera vez, describimos el androceo, el fruto, la semilla, pedicelo floral y frutal, cinco tipos de tricomas y cinco tipos de estomas en el perianto. Encontramos diferencias en la forma del tejido de transmisión y del tipo de óvulo respecto de lo previamente descripto. Además, localizamos el parénquima y las células epidérmicas secretoras del nectario. En el contexto de la familia Solanaceae, discutimos la función y valor diagnóstico de las estructuras descriptas.Solanaceae is a family with nearly 2400 species of cosmopolitan distribution. Vassobia breviflora is the only species of the genus present in Argentina. The goal of this work was to review and characterize the anatomy of the flower and fruit of V. breviflora from samples collected in populations of Yungas in the argentine Northwest. Conventional anatomical techniques were applied. The results showed that most flower, fruit and seed structures did not differ from those previously reported regarding the structural organization described for other species of the Solanaceae family. However, for the first time, we described the androecium, fruit, seed, floral and fruit pedicels, five types of tricomes and five types of stomata in the perianth. We found some differences in the shape of the transmission tissue and in the type of ovule with respect to that previously reported. Also, we located the parenchyma and the epidermic secretory cells of the nectary. In the context of the family Solanaceae, we discussed the function and diagnostic value of the described structures.Fil: Bernacki, F. G.. Fundación Miguel Lillo; ArgentinaFil: Albornoz, P. L.. Fundación Miguel Lillo; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; ArgentinaFil: Valoy, M.. Fundación Miguel Lillo; ArgentinaFil: Ordano, Mariano Andrés. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

BRITE-Constellation: Data processing and photometry

The BRITE mission is a pioneering space project aimed at the long-term photometric monitoring of the brightest stars in the sky by means of a constellation of nano-satellites. Its main advantage is high photometric accuracy and time coverage inaccessible from the ground. The main aim of this paper is the presentation of procedures used to obtain high-precision photometry from a series of images acquired by the BRITE satellites in two modes of observing, stare and chopping. We developed two pipelines corresponding to the two modes of observing. The assessment of the performance of both pipelines is presented. It is based on two comparisons, which use data from six runs of the UniBRITE satellite: (i) comparison of photometry obtained by both pipelines on the same data, which were partly affected by charge transfer inefficiency (CTI), (ii) comparison of real scatter with theoretical expectations. It is shown that for CTI-affected observations, the chopping pipeline provides much better photometry than the other pipeline. For other observations, the results are comparable only for data obtained shortly after switching to chopping mode. Starting from about 2.5 years in orbit, the chopping mode of observing provides significantly better photometry for UniBRITE data than the stare mode. This paper shows that high-precision space photometry with low-cost nano-satellites is achievable. The proposed meth- ods, used to obtain photometry from images affected by high impulsive noise, can be applied to data from other space missions or even to data acquired from ground-based observations

Predicting STEM Achievement with Learning Management System Data: Prediction Modeling and a Test of an Early Warning System

ABSTRACT Learning management systems log users' behaviors, which can be used to predict achievement in a course. This paper examines the implications of data representations (e.g., dichotomous vs. count vs. principled, per learning theory) and applies forward selection algorithms to predict achievement in a biology course. Accuracy is compared across models. The paper closes with a description of an ongoing experiment that employs the prediction model, tests how multiple versions of an early alert message impact students' access of learning resources, and compares the influence of messaging approaches related to personalization and feedback

Digestive tract morphometry and breast muscle microstructure in spent breeder ducks maintainedin a conservation programme of genetic resources

The objective of this study was to compare three genetic groups of ducks: P9 (French Pekin), K2 (bred from wild mallards – Anas platyrhynchos L. and Pekin duck), and KhO1 (hybrid of Khaki Campbell drake and Orpington Fauve duck) after two breeding seasons for body weight and length, length of intestine and its segments, percentage of other internal organs, and breast muscle microstructure. The study used 60 ducks, 20 birds (10 males and 10 females) from each genetic group. At 110 weeks of age, P9 ducks exhibited significantly (p&lt;0.05) greater body weight and length, and length of intestine and its segments (except for colon length) compared to K2 and KhO1 ducks. KhO1 ducks had significantly shorter jejunum and ileum compared to K2 birds. The lighter K2 and KhO1 ducks had significantly greater relative length of intestine and its segments. In P9 ducks, liver, heart, and gizzard were heavier and spleen percentage in body weight significantly lower than in K2 and KhO1 birds. KhO1 ducks had a significantly higher percentage of proventriculus compared to the other duck groups. The different genetic origins of the ducks had no effect on microstructural characteristics of m. pectoralis superficialis except for perimysium and endomysium thickness. Our study provided information about differences in the digestive tract morphometry and breast muscle microstructure of ducks from three genetic groups after two reproductive seasons, which are maintained in a conservation programme of genetic resources in Poland.</p

Thermo-mechanical factors influencing annealing twin development in nickel during recrystallization

Abstract The effects of prior stored energy level, annealing temperature, heating velocity, and initial grain size on annealing twin development during static recrystallization of commercially pure nickel (99.999 %) are investigated. The twin content (measured as the twin boundary density or as the number of twins per grain) at the end of recrystallization is shown to be primarily influenced by the prior stored energy level and by the initial grain size, but the effects of heating rate and the annealing temperature are negligible. Taken together, the results are consistent with a new proposition that roughness of the recrystallization front promotes the formation of annealing twins during recrystallization