Some remarks on particle size effects on the abrasion of a range of Fe based alloys

The low-stress three body abrasion behaviour of a range of steels was investigated. The tests were carried out in a rubber wheel tester (according to ASTM G65-94, reapproved in 2000) at room temperature. The abrasive particles used were angular alumina particles of four different sizes. The results showed that, in general, the smaller particles (50 8m and 125 8m average size) caused more damage. With these particles, observations of surface morphology indicarted a more intense cutting and ploughing action, leading to more damage, whereas bigger particles i.e. larger 250 8m and 560 8m particles produced less damage, and their action involved more plastic deformation type wear. The 304 SS had a lower abrasion resistance than the 310 SS. For the austentic and ferritic steels the subsurface deformation was larger for impact with the coarser particles. Variations in substrate hardness had no effect on the abrasive behaviour observed. On the whole, the hardest steel (mild steel in martensitic condition) showed the higher extent of damage, irrespective of particle size

Learning a logistic regression with the help of unknown features at prediction stage

The use of features available at training time, but not at prediction time, as additional information for training models is known as learning using privileged information paradigm. In this paper, the handling of privileged features is addressed from the logistic regression perspective, commonly used in the clinical setting. Two new proposals, LOGIT+ and LRPROB+, learned with the influence of privileged features and preserving the interpretability of conventional logistic regression, are proposed. Experimental results on datasets report improvements of our proposals over the performance of traditional logistic regression learned without privileged information

Ratchet universality in the bidirectional escape from a symmetric potential well

The present work discusses symmetry-breaking-induced bidirectional escape from a symmetric metastable potential well by the application of zero-average periodic forces in the presence of dissipation. We characterized the interplay between heteroclinic instabilities leading to chaotic escape and breaking of a generalized parity symmetry leading to directed ratchet escape to an attractor either at infinity or at -infinity. Optimal enhancement of directed ratchet escape is found to occur when the wave form of the zero-average periodic force acting on the damped driven oscillator matches as closely as possible to a universal wave form, as predicted by the theory of ratchet universality. Specifically, the optimal approximation to the universal force triggers the almost complete destruction of the nonescaping basin for driving amplitudes which are systematically lower than those corresponding to a symmetric periodic force having the same period. We expect that this work could be potentially useful in the control of elementary dynamic processes characterized by multidirectional escape from a potential well, such as forced chaotic scattering and laser-induced dissociation of molecular systems, among others

Genetics of obesity: gene x nutrient interactions

Obesity results from a long-term positive energy balance, in which gene-related differences may account for some of the disparities found in weight gain among populations. However, the rising prevalence of obesity in developed and developing societies must reflect lifestyle changes. Despite that the genetic background remains stable over many generations, obesity may be derived from a failure on the homeostasis systems, as a consequence of a dysfunction at the genetic level, which may be affected by changing environmental exposure (dietary habits, sedentarism, etc). In practice, obesity risk at least depends on two important factors, which mutually interact: 1) genetic variants and gene expression changes in candidate genes and 2) exposure to environmental risk factors. Disagreements among studies involving gene-nutrient interactions may reflect the difficulty of accurate measurement of specific types of dietary macro and micronutrients intake as well of phenotype assessment rather than a discrepancy in biological relevance. Identification of individuals who are genetically more likely to respond to particular dietary changes may be important for successful intervention in obesity treatment, since gene screening will allow health professionals to tailor-design weight management and dietary guidance in individuals with a genetic predisposition to become obese

Interaction between genes and lifestyle factors on obesity.

Obesity originates from a failure of the body-weight control systems, which may be affected by changing environmental influences. Basically, the obesity risk depends on two important mutually-interacting factors: (1) genetic variants (single-nucleotide polymorphisms, haplotypes); (2) exposure to environmental risks (diet, physical activity etc.). Common single-nucleotide polymorphisms at candidate genes for obesity may act as effect modifiers for environmental factors. More than 127 candidate genes for obesity have been reported and there is evidence to support the role of twenty-two genes in at least five different populations. Gene-environment interactions imply that the synergy between genotype and environment deviates from either the additive or multiplicative effect (the underlying model needs to be specified to appraise the nature of the interaction). Unravelling the details of these interactions is a complex task. Emphasis should be placed on the accuracy of the assessment methods for both genotype and lifestyle factors. Appropriate study design (sample size) is crucial in avoiding false positives and ensuring that studies have enough power to detect significant interactions, the ideal design being a nested case-control study within a cohort. A growing number of studies are examining the influence of gene-environmental interactions on obesity in either epidemiological observational or intervention studies. Positive evidence has been obtained for genes involved in adiposity, lipid metabolism or energy regulation such as PPARgamma2 (Pro12Ala), beta-adrenoceptor 2 (Gln27Glu) or uncoupling proteins 1, 2 and 3. Variants on other genes relating to appetite regulation such as melanocortin and leptin receptors have also been investigated. Examples of some recently-identified interactions are discussed

Nutrición en el enfermo con fibrosis quística

La fibrosis quística es una enfermedad que se asocia a una mutación de un gen localizado en el brazo largo del cromosoma 7. Esta enfermedad multisistémica afecta especialmente a los pulmones y al páncreas exocrino, lo cual supone el trastorno más influyente en la nutrición de estos pacientes. Generalmente, la suplementación con enzimas pancreáticas es necesaria como elemento terapéutico. La prevalencia de diabetes en esta enfermedad aumenta con la edad, mientras que la afectación hepática clínica es menos frecuente y otras complicaciones intestinales como el ileomeconial, el reflujo gastroesofágico o la obstrucción del intestino distal pueden condicionar también la malnutrición. La prevalencia de la desnutrición en los pacientes con fibrosis quística es elevada, aunque variable, y se asocia directamente con el estado pulmonar y la supervivencia. La terapia nutricional ha adquirido gran importancia ya que se asocia con un mejor crecimiento y mejora o estabilización de la función pulmonar, por lo que debe ser una parte integral del tratamiento de estos pacientes

Application of the trajectory error matrix for assessing the temporal transferability of OBIA for slum detection

High temporal and spatial-resolution imageries are a valuable data source for slum monitoring. However, the transferability of OBIA methods across space and time remains problematic, due to the complexity of the term “slum”. Hence, transparency is important when analysing the transferability of OBIA methods for slum mapping. Our research developed a framework for measuring the temporal transferability of OBIA methods employing the trajectory error matrix (TEM). We found relatively low trajectory accuracies indicating low temporal transferability of OBIA methods for slum monitoring using point-based assessment methods. However, the analysis of change needs to be combined with an analysis of the certainty of this change by considering the context of the change to deal with common problems such as variations of the viewing angles and uncertainties in producing reference data on slums

Learning Network Assisted by Means of Symbolic Computation

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