Visual processing of concentric sine-wave gratings in adolescents and adults

The aim of this study was to compare the contrast visual processing of concentric sinusoidal gratings stimuli between adolescents and adults. The study included 20 volunteers divided into two groups: 10 adolescents aged 13-19 years (M=16.5, SD=1.65) and 10 adults aged 20-26 years (M=21.8, SD=2.04). In order to measure the contrast sensitivity at spatial frequencies of 0.6, 2.5, 5 and 20 degrees of visual angle (cpd), it was used the psychophysical method of two alternative forced choice (2AFC). A One Way ANOVA performance showed a significant difference in the comparison between groups: F [(4, 237)=3.74, p<.05]. The post-hoc Tukey HSD showed a significant difference between the frequencies of 0.6 (p <.05) and 20 cpd (p<.05). Thus, the results showed that the visual perception behaves differently with regard to the sensory mechanisms that render the contrast towards adolescents and adults. These results are useful to better characterize and comprehend human vision development.

Self-medication and related terms: a conceptual reflection

Introduction: self-medication has become a growing practice in the world population. This phenomenon has been promoted as a form of self-care, with a positive impact on reducing spending in health systems, however there is concern about the potential negative effects related to inadequate diagnosis and treatment, which can affect health of individuals. This dual perception of the phenomenon is partly related to a variety of terms and concepts used, that make difficult its theoretical and empirical approach. Harmonization of the definitions involved is required in order to make adequate epidemiological comparisons. Objectives: analyze the concept of self medication and related terms from the definitions in the literature of the subject. Conclusions: in the last four decades it has been an evolution of both the wording and the definitions related to self-medication, from a very simple concept that implies the absence of prescription, to more complex ones that encompass very diverse behaviors, even those mediated by an act of prescription but not followed or not completed by the patient. Additionally the conceptual proliferation seen, justify the ordering of the terms related to self-medication. This paper presents a proposal for classification in four groups: a. self-medication, b. self care, c. pharmaceutical preparations and medicines, and d. prescription. This proposal should facilitate the exploration and analysis of the phenomenon and allow future theoretical approaches.

Al – Qaeda and the international politics: a teorical Reflection

Through the study of the relationship between non-state actors and states, is pretended to analyze the role of Al-Qaeda in international politics. It is argued that Al-Qaeda tries or has the ability to promote or accelerate changes in the power  structure, where stands the American hegemony and the pursuit of balance by  various actors, implementing asymmetric strategies as counter-hegemonic responses.

Towards the 3rd wave school leadership. 'Hacia el 3er paradigma del liderazgo de la escuela'.

Resumen basado en el de la publicación

New wave!

Ayudas a la Innovación Educativa, 1997-98. Anexo Memoria en C-Innov. 54

Integrative Behavioral Couple Therapy (IBCT) as a third-wave therapy

Resumen tomado de la publicaci??n

Building Professional Capacity Aiming to Improve the Educational Position of Migrant Children : a reflection on the Sirius network activities

Resumen basado en el de la publicaci??n

Simple finite field nuclear relaxation method for calculating vibrational contribution to degenerate four-wave mixing

A simple extended finite field nuclear relaxation procedure for calculating vibrational contributions to degenerate four-wave mixing (also known as the intensity-dependent refractive index) is presented. As a by-product one also obtains the static vibrationally averaged linear polarizability, as well as the first and second hyperpolarizability. The methodology is validated by illustrative calculations on the water molecule. Further possible extensions are suggested

Evolving definition of sociomuseology : proposal for reflection

Sociomuseology expresses a considerable amount of the effort made to suit museological facilities to the conditions of contemporary society. The process of opening up the museum, as well as its organic relation with the social context that infuses it with life, has resulted in the need to structure and clarify the relations, notions and concepts that may define this process. Sociomuseology is thus a scientific field of teaching, research and performance which emphasizes the articulation of museology, in particular, with the areas of knowledge covered by Human Sciences, Development Studies, Services Science, and Urban and Rural Planning. The multidisciplinary approach of Sociomuseology aims to strengthen the acknowledgement of museology as a resource for the sustainable development of Humanity, based on equal opportunities as well as social and economic inclusion. Sociomuseology bases its social intervention on mankind’s cultural and natural heritage, both tangible and intangible. What characterizes Sociomuseology is not so much the nature of its premises and its goals, as is the case with other areas of knowledge, but the interdisciplinary focus which makes it draw on perfectly consolidated areas of knowledge and relate them with Museology itself.

Are there hazardous auditory effects of high-frequency turbines and ultrasonic dental scalers on dental professionals?

The purpose of this pilot study was to survey dentists in the St. Louis area to assess their subjective opinion of commonly used dental handpieces as well as history of noise exposure and use of hearing protection. Selected handpieces were then chosen to measure their output levels and determine if emissions are hazardous to the auditory system.

The counter-propagating Rossby-wave perspective on baroclinic instability. I: Mathematical basis

It is shown that Bretherton's view of baroclinic instability as the interaction of two counter-propagating Rossby waves (CRWs) can be extended to a general zonal flow and to a general dynamical system based on material conservation of potential vorticity (PV). The two CRWs have zero tilt with both altitude and latitude and are constructed from a pair of growing and decaying normal modes. One CRW has generally large amplitude in regions of positive meridional PV gradient and propagates westwards relative to the flow in such regions. Conversely, the other CRW has large amplitude in regions of negative PV gradient and propagates eastward relative to the zonal flow there. Two methods of construction are described. In the first, more heuristic, method a ‘home-base’ is chosen for each CRW and the other CRW is defined to have zero PV there. Consideration of the PV equation at the two home-bases gives ‘CRW equations’ quantifying the evolution of the amplitudes and phases of both CRWs. They involve only three coefficients describing the mutual interaction of the waves and their self-propagation speeds. These coefficients relate to PV anomalies formed by meridional fluid displacements and the wind induced by these anomalies at the home-bases. In the second method, the CRWs are defined by orthogonality constraints with respect to wave activity and energy growth, avoiding the subjective choice of home-bases. Using these constraints, the same form of CRW equations are obtained from global integrals of the PV equation, but the three coefficients are global integrals that are not so readily described by ‘PV-thinking’ arguments. Each CRW could not continue to exist alone, but together they can describe the time development of any flow whose initial conditions can be described by the pair of growing and decaying normal modes, including the possibility of a super-modal growth rate for a short period. A phase-locking configuration (and normal-mode growth) is possible only if the PV gradient takes opposite signs and the mean zonal wind and the PV gradient are positively correlated in the two distinct regions where the wave activity of each CRW is concentrated. These are easily interpreted local versions of the integral conditions for instability given by Charney and Stern and by Fjørtoft.

The counter-propagating Rossby-wave perspective on baroclinic instability. II: Application to the Charney model

The constant-density Charney model describes the simplest unstable basic state with a planetary-vorticity gradient, which is uniform and positive, and baroclinicity that is manifest as a negative contribution to the potential-vorticity (PV) gradient at the ground and positive vertical wind shear. Together, these ingredients satisfy the necessary conditions for baroclinic instability. In Part I it was shown how baroclinic growth on a general zonal basic state can be viewed as the interaction of pairs of ‘counter-propagating Rossby waves’ (CRWs) that can be constructed from a growing normal mode and its decaying complex conjugate. In this paper the normal-mode solutions for the Charney model are studied from the CRW perspective. Clear parallels can be drawn between the most unstable modes of the Charney model and the Eady model, in which the CRWs can be derived independently of the normal modes. However, the dispersion curves for the two models are very different; the Eady model has a short-wave cut-off, while the Charney model is unstable at short wavelengths. Beyond its maximum growth rate the Charney model has a neutral point at finite wavelength (r=1). Thereafter follows a succession of unstable branches, each with weaker growth than the last, separated by neutral points at integer r—the so-called ‘Green branches’. A separate branch of westward-propagating neutral modes also originates from each neutral point. By approximating the lower CRW as a Rossby edge wave and the upper CRW structure as a single PV peak with a spread proportional to the Rossby scale height, the main features of the ‘Charney branch’ (0wave propagation mechanism and the CRW interaction. The behaviour of the Charney modes and the first neutral branch, which rely on tropospheric PV gradients, are arguably more applicable to the atmosphere than modes of the Eady model where the positive PV gradient exists only at the tropopause

The counterpropagating Rossby wave perspective on Kelvin Helmholtz instability as a limiting case of a Rayleigh shear layer with zero width

The Kelvin Helmholtz (KH) problem, with zero stratification, is examined as a limiting case of the Rayleigh model of a single shear layer whose width tends to zero. The transition of the Rayleigh modal dispersion relation to the KH one, as well as the disappearance of the supermodal transient growth in the KH limit, are both rationalized from the counterpropagating Rossby wave perspective.