Stability of Runge–Kutta–Nyström methods

AbstractIn this paper, a general and detailed study of linear stability of Runge–Kutta–Nyström (RKN) methods is given. In the case that arbitrarily stiff problems are integrated, we establish a condition that RKN methods must satisfy so that a uniform bound for stability can be achieved. This condition is not satisfied by any method in the literature. Therefore, a stable method is constructed and some numerical comparisons are made

Changes in frequency-doubling perimetry in patients with type i diabetes prior to retinopathy

Purpose. To evaluate the ability of frequency-doubling technology (FDT) perimetry in detecting visual field defects in young adults with type I diabetes prior to retinopathy or with minor retinovascular changes. Methods. This comparative cross-sectional study included 30 healthy subjects and 73 age-matched patients with type I diabetes mellitus. All subjects underwent a full ocular examination including an FDT with the threshold C-20-5 strategy. Only one eye per subject was randomly included in the statistical analysis. FDT results and time to perform the test were compared between the groups. Results. The mean age was 27.1 years in the control group and 26.6 years in the diabetic group ( ). The mean period from the onset of diabetes was years, while minimal retinovascular changes were observed in 18 eyes. Mean deviation of FDT did not differ between the groups. Although global indices of FDT were within normal limits, pattern standard deviation of FDT was higher in the diabetic group ( ). The area under the receiver operating characteristic curve was 0.647 for pattern standard deviation of FDT (standard error = 0.052; ). Conclusion. FDT can detect retinal dysfunctions in diabetic patients prior to the onset of significant vascular complications

Using EIS to analyse samples of Al–Mg alloy AA5083 treated by thermal activation in cerium salt baths

This paper describes a study undertaken of the morphological and anticorrosive characteristics of surface layers formed on the Al–Mg alloy AA5083 from solutions of Ce(III), by means of various heat treatments while immersed in baths of cerium salts. SEM/EDS studies have demonstrated the existence of a heterogeneous layer formed by a film of aluminium oxide/hydroxide on the matrix and a series of dispersed islands of cerium deposited on the cathodic intermetallics. With the object of evaluating the degree of protection provided by the layers formed and of characterising the particular contribution of the electrochemical response of the system in NaCl, the results obtained by means of EIS are presented and discusse

The interaction of depressive symptoms and hazardous drinking in relation to tobacco craving among treatment seeking depressed smokers: Sex differences

Objectives: The present study sought to address whether there is sex effect in the interactive effect between depressive symptoms and hazardous drinking in the prediction of smoking craving after cognitive-behavioral smoking cessation treatment among those with at least mild depression. Methods: Participants (n=114, mean age 42.0, SD=9.73, 64% women) were treatment-seeking smokers who attended 6 weekly 1-hour sessions involving psychological treatment for cessation. Participants reported depressive symptoms and alcohol use at baseline and reported craving at baseline and after treatment. Results: Results indicated that there was a statistically significant 3-way interaction (depression by alcohol use by sex) for smoking craving (B=-0.30, standard error [SE]=0.14, P=0.042) and appetitive craving (B=-.21, SE=0.09, P=0.031), but not negative reinforcement craving. The form of the significant interactions indicted that higher levels of depressive symptoms and alcohol use were related to greater levels of craving at the end of treatment only among men. Conclusions: The current findings provide novel empirical evidence suggesting that there is a clinically relevant interplay between depressive symptoms and alcohol use regarding general craving and appetitive craving among male treatment-seeking smokers. Although the present results should be replicated in larger samples, this type of research can inform the development of sex-specific interventions for smoking cessation

What are microRNAs? Potential biomarkers and therapeutic targets in osteoporosis

Los micro-ARN (miRs) son pequeñas moléculas de ARN no codificantes que regulan la expresión génica a nivel post-transcripcional. Generalmente actúan sobre la expresión genética mediante el silenciamiento o degradación de los ARNm, y están implicados en la regulación de varios procesos biológicos, como la diferenciación celular, la proliferación, la apoptosis y en el desarrollo embrionario y tisular. Actualmente son un importante foco de interés para el estudio de diversas enfermedades como el cáncer o la diabetes mellitus tipo 2. A nivel del metabolismo óseo, están surgiendo diversos miRs implicados en su regulación, abriendo un campo de investigación importante para identificar nuevos biomarcadores para el diagnóstico de la enfermedad osteoporótica, de su evolución, así como para diseñar nuevas terapias farmacológicas.Micro-RNAs (miRs) are small non-coding RNA molecules that regulate gene expression at post-transcriptional level. Generally, they act on gene expression by silencing or degrading mRNAs, and are involved in regulating various biological processes, such as cell differentiation, proliferation, apoptosis and in embryonic and tissue development. They are currently a major focus of interest in the study of various diseases such as cancer or type 2 diabetes mellitus. At level of bone metabolism, various miRs are emerging that are involved in their regulation, opening an important research field to identify new biomarkers for diagnosis of osteoporosis and its development, and to design new drug therapies