Attention-deficit hyperactivity disorder symptoms and lead exposure in children: A systematic review of literature

Blood lead levels > 10 µg/dL are known to affect various areas of the brain that influence behavior and cause many other health problems in children. As a result, the Centers for Disease Control and Prevention (CDC) set the blood lead action level at 10 µg/dL. However, recent research provides evidence that blood lead levels <10 µg/dL also may lead to behavioral problems in children. With the recent increase in diagnosis of Attention-Deficit Hyperactivity Disorder (ADHD) in children in the U.S. it is important to determine possible environmental toxins such as lead that may play a role in causing ADHD symptoms. The aim of this systematic review of the literature was to identify recent published studies that examine an association between blood lead levels < 10 µg/dL and ADHD symptoms in children in order to summarize their findings and describe major gaps in the literature. Although available research is limited, the articles reviewed indicate that blood lead at levels much below the CDC action level of 10 µg/dL may affect a child's level of attention, hyperactivity, impulsivity and ADHD diagnosis. Additional prospective research is warranted in order to inform the revision of current blood lead action levels as well as better elucidate the relationship between lead and ADHD diagnoses.^

Assessing the Environmental Protection Agency's guidelines for cumulative risk assessment: Are they suitable for state agencies and EPA regional offices?

In the field of health risk analysis, cumulative risk assessment (CRA) is a necessary, although undeniably more complex approach to understanding the mixture of stressors, whether chemical or psychosocial, that exist in our environment, in all the pathways through which the chemicals may evolve—air, soil, or water, as well as the accumulation of these exposures over time. Related, or attached to the developing awareness of scientists understanding this mix of combined health effects is the burgeoning of the environmental justice movement, in which educated community advocates and even affected community members have called attention to evidence of a higher pollution burden in minority and/or lower SES communities. The intention of this paper is to 1) examine the development and understanding of CRA, primarily by the U.S. Environmental Protection Agency; 2) to assess several states agencies and some EPA regional offices' interpretation of CRA, again based primarily on EPA guidance, and 3) to analyze how CRA might be refined in its implementation—giving some cues as to how the EPA may more effectively interact with communities interested in CRA.^

The attention/support to students in the socio-labor transition

In the present paper I intend to put forward some inquiries regarding the socio-labor guidance and transition of the young people in the co-ordinates of contemporary society. The outstanding paradox in which some young people are immersed when trying to get a first, second, third employment is also analyzed: "The job of looking for a job". This is a common experience shared by many young people when they try to find a place in the complex labor panorama. Looking for a job is a recurrent situation in contemporary society, given the high dose of precarious employment in which the productive world moves. Life-long jobs belong to the past and what is normal is that people strive to enter the competitive labor market repeatedly. Moreover, the paper offers the partial results of a larger research project that approaches tutorship, decision taking and expectations before the academic-labor future of the studentship in the last years of secondary school. Finally, I suggest some insights in the line that it is not longer feasible to work with old-fashioned guidance, trying to channel people's vocation and offering them information so that they get a job that provides them with the happiness of "doing what you like". Behind these ideas lay the normal biographies, the predictable itineraries. Labor market complexity makes the transition to working life very difficult. Once immersed in it, biographies and labor itineraries are constructed and reconstructed at the rhythm of the changing fortunes of times.

Psychosocial construction of time and social change

This paper analyzes the psychosocial construction of the conceptions of time and social change, and their relation with the notion of progress set up by modernity as well as their contradictory aspects, considering their historicity as psychosocial and social phenomena. The social construction of the notion of time is discussed; it responds to social organization forms, thus turning the social changes into historical and temporal landmarks. The association between social changes and social movements is argued and the concept of progress is deconstructed. Finally, the importance of the idea of movement in the construction of time, change and progress concepts is pointed out; it is also explained how modernity imbued such notions with direction and goals, in the direction of an arrow, according to the prevailing interests, while modeling them in its own image and likeness.

The attention/support to students in the socio-labor transition

In the present paper I intend to put forward some inquiries regarding the socio-labor guidance and transition of the young people in the co-ordinates of contemporary society. The outstanding paradox in which some young people are immersed when trying to get a first, second, third employment is also analyzed: "The job of looking for a job". This is a common experience shared by many young people when they try to find a place in the complex labor panorama. Looking for a job is a recurrent situation in contemporary society, given the high dose of precarious employment in which the productive world moves. Life-long jobs belong to the past and what is normal is that people strive to enter the competitive labor market repeatedly. Moreover, the paper offers the partial results of a larger research project that approaches tutorship, decision taking and expectations before the academic-labor future of the studentship in the last years of secondary school. Finally, I suggest some insights in the line that it is not longer feasible to work with old-fashioned guidance, trying to channel people's vocation and offering them information so that they get a job that provides them with the happiness of "doing what you like". Behind these ideas lay the normal biographies, the predictable itineraries. Labor market complexity makes the transition to working life very difficult. Once immersed in it, biographies and labor itineraries are constructed and reconstructed at the rhythm of the changing fortunes of times.

Psychosocial construction of time and social change

This paper analyzes the psychosocial construction of the conceptions of time and social change, and their relation with the notion of progress set up by modernity as well as their contradictory aspects, considering their historicity as psychosocial and social phenomena. The social construction of the notion of time is discussed; it responds to social organization forms, thus turning the social changes into historical and temporal landmarks. The association between social changes and social movements is argued and the concept of progress is deconstructed. Finally, the importance of the idea of movement in the construction of time, change and progress concepts is pointed out; it is also explained how modernity imbued such notions with direction and goals, in the direction of an arrow, according to the prevailing interests, while modeling them in its own image and likeness.

The attention/support to students in the socio-labor transition

In the present paper I intend to put forward some inquiries regarding the socio-labor guidance and transition of the young people in the co-ordinates of contemporary society. The outstanding paradox in which some young people are immersed when trying to get a first, second, third employment is also analyzed: "The job of looking for a job". This is a common experience shared by many young people when they try to find a place in the complex labor panorama. Looking for a job is a recurrent situation in contemporary society, given the high dose of precarious employment in which the productive world moves. Life-long jobs belong to the past and what is normal is that people strive to enter the competitive labor market repeatedly. Moreover, the paper offers the partial results of a larger research project that approaches tutorship, decision taking and expectations before the academic-labor future of the studentship in the last years of secondary school. Finally, I suggest some insights in the line that it is not longer feasible to work with old-fashioned guidance, trying to channel people's vocation and offering them information so that they get a job that provides them with the happiness of "doing what you like". Behind these ideas lay the normal biographies, the predictable itineraries. Labor market complexity makes the transition to working life very difficult. Once immersed in it, biographies and labor itineraries are constructed and reconstructed at the rhythm of the changing fortunes of times.

Psychosocial construction of time and social change

This paper analyzes the psychosocial construction of the conceptions of time and social change, and their relation with the notion of progress set up by modernity as well as their contradictory aspects, considering their historicity as psychosocial and social phenomena. The social construction of the notion of time is discussed; it responds to social organization forms, thus turning the social changes into historical and temporal landmarks. The association between social changes and social movements is argued and the concept of progress is deconstructed. Finally, the importance of the idea of movement in the construction of time, change and progress concepts is pointed out; it is also explained how modernity imbued such notions with direction and goals, in the direction of an arrow, according to the prevailing interests, while modeling them in its own image and likeness.

Effects of binaural stimulation in attention and EEG

When two pure tones of slightly different frequency are presented separately to each ear, the listener perceives a third single tone with amplitude variations at a frequency that equals the difference between the two tones, this perceptual illusion is known as binaural auditory beat. There are anecdotal reports that suggest that the binaural beat can entrain EEG activity and may affect the arousal levels, although few studies have been published. There is a need for double-blind, well-designed studies in order to establish a solid foundation for these sounds, as most of the documented benefits come from self-reported cases that could be affected by placebo effect. As BB’s are a cheap technology (it even exists a free open source programmable bin aural-beat generator on the internet named Gnaural), any achievement in this area could be of public interest. The aim in our research was to explore the potential of BB’s in a particular field: tasks that require focus and concentration. In order to detect changes in the brain waves that could relate to any particular improvement, EEG recordings of a small sample of individuals were also obtained. In this study we compare the effect of different binaural stimulation in 7 EEG frequency ranges, 78 participants were exposed to 20 min binaural beat stimulation. The effects were obtained both qualitative with cognitive test and quantitative with EEG analysis. Results suggest no significant statistical improvement in 20 min stimulation.

Effect of binaural stimulation on attention and EEG

When two pure tones of slightly different frequency are presented separately to each ear, the listener perceives a third single tone with amplitude variations at a frequency that equals the difference between the two tones; this perceptual illusion is known as the binaural auditory beat (BB). There are anecdotal reports that suggest that the binaural beat can entrain EEG activity and may affect the arousal levels, although few studies have been published. There is a need for double-blind, well-designed studies in order to establish a solid foundation for these sounds, as most of the documented benefits come from self-reported cases that could be affected by placebo effect. As BBs are a cheap technology (it even exists a free open source programmable binaural- beat generator on the Internet named Gnaural), any achievement in this area could be of public interest. The aim in our research was to explore the potential of BBs in a particular field: tasks that require focus and concentration. In order to detect changes in the brain waves that could relate to any particular improvement, EEG recordings of a small sample of individuals were also obtained. In this study we compare the effect of different binaural stimulation in 7 EEG frequency ranges. 78 participants were exposed to 20-min binaural beat stimulation. The effects were obtained both quali- tative with cognitive test and quantitative with EEG analysis. Results suggest no significant statistical improvement in 20-min stimulation.

Monitoring visual attention on a neurorehabilitation environment based on interactive video

The use of new technologies in neurorehabilitation has led to higher intensity rehabilitation processes, extending therapies in an economically sustainable way. Interactive Video (IV) technology allows therapists to work with virtual environments that reproduce real situations. In this way, patients deal with Activities of the Daily Living (ADL) immersed within enhanced environments [1]. These rehabilitation exercises, which focus in re-learning lost functions, will try to modulate the neural plasticity processes [2]. This research presents a system where a neurorehabilitation IV-based environment has been integrated with an eye-tracker device in order to monitor and to interact using visual attention. While patients are interacting with the neurorehabilitation environment, their visual behavior is closely related with their cognitive state, which in turn mirrors the brain damage condition suffered by them [3] [4]. Patients’ gaze data can provide knowledge on their attention focus and their cognitive state, as well as on the validity of the rehabilitation tasks proposed [5].

Background noise and its influence on the brain waves related to attention

In this work, we present a study whose objective is to prove the influence of background noise produced inside university facilities on the brain waves related to attention processes. Recordings of background noise were carried out in study areas inside university facilities. Volunteers were asked to perform an attention test without any background noise but also while being exposed to the sound recordings, and their cerebral activity was recorded through electroencephalography (EEG). After the application of the test in both conditions, changes in the frequency bands related to attention processes (beta 13-30 Hz and theta 4-7 Hz) were studied. The results of this study show that when the students were performing the test while being exposed to background noise, both beta and theta frequency bands decreased statistically significantly. Because attentional improvement is related to increases of the beta and theta waves, we believe that those decreases are directly related to a lack of attention caused by the exposure to background noise. Nevertheless, the results do not allow us to conclude that background noise produced inside university facilities has an influence on the attentional processes.

A journey through Spain in the years 1786 and 1787 : with particular attention to the agriculture, manufactures, commerce, population, taxes and revenue of that country and remarks in passing through a part of France

Sign.: A4, B-Z8, Aa-Bb8, Cc4

A journey through Spain in the years 1786 and 1787 : with particular attention to the agriculture, manufactures, commerce, population, taxes, and revenue of that country and remarks in passing through a part of France

Contiene: "Appendix" con las equivalencias entre la moneda castellana y la inglesa y un indice de nombres geograficos

Visual attention and perception models for assessing quality in 2D and 3D stereoscopic video

La medida de calidad de vídeo sigue siendo necesaria para definir los criterios que caracterizan una señal que cumpla los requisitos de visionado impuestos por el usuario. Las nuevas tecnologías, como el vídeo 3D estereoscópico o formatos más allá de la alta definición, imponen nuevos criterios que deben ser analizadas para obtener la mayor satisfacción posible del usuario. Entre los problemas detectados durante el desarrollo de esta tesis doctoral se han determinado fenómenos que afectan a distintas fases de la cadena de producción audiovisual y tipo de contenido variado. En primer lugar, el proceso de generación de contenidos debe encontrarse controlado mediante parámetros que eviten que se produzca el disconfort visual y, consecuentemente, fatiga visual, especialmente en lo relativo a contenidos de 3D estereoscópico, tanto de animación como de acción real. Por otro lado, la medida de calidad relativa a la fase de compresión de vídeo emplea métricas que en ocasiones no se encuentran adaptadas a la percepción del usuario. El empleo de modelos psicovisuales y diagramas de atención visual permitirían ponderar las áreas de la imagen de manera que se preste mayor importancia a los píxeles que el usuario enfocará con mayor probabilidad. Estos dos bloques se relacionan a través de la definición del término saliencia. Saliencia es la capacidad del sistema visual para caracterizar una imagen visualizada ponderando las áreas que más atractivas resultan al ojo humano. La saliencia en generación de contenidos estereoscópicos se refiere principalmente a la profundidad simulada mediante la ilusión óptica, medida en términos de distancia del objeto virtual al ojo humano. Sin embargo, en vídeo bidimensional, la saliencia no se basa en la profundidad, sino en otros elementos adicionales, como el movimiento, el nivel de detalle, la posición de los píxeles o la aparición de caras, que serán los factores básicos que compondrán el modelo de atención visual desarrollado. Con el objetivo de detectar las características de una secuencia de vídeo estereoscópico que, con mayor probabilidad, pueden generar disconfort visual, se consultó la extensa literatura relativa a este tema y se realizaron unas pruebas subjetivas preliminares con usuarios. De esta forma, se llegó a la conclusión de que se producía disconfort en los casos en que se producía un cambio abrupto en la distribución de profundidades simuladas de la imagen, aparte de otras degradaciones como la denominada “violación de ventana”. A través de nuevas pruebas subjetivas centradas en analizar estos efectos con diferentes distribuciones de profundidades, se trataron de concretar los parámetros que definían esta imagen. Los resultados de las pruebas demuestran que los cambios abruptos en imágenes se producen en entornos con movimientos y disparidades negativas elevadas que producen interferencias en los procesos de acomodación y vergencia del ojo humano, así como una necesidad en el aumento de los tiempos de enfoque del cristalino. En la mejora de las métricas de calidad a través de modelos que se adaptan al sistema visual humano, se realizaron también pruebas subjetivas que ayudaron a determinar la importancia de cada uno de los factores a la hora de enmascarar una determinada degradación. Los resultados demuestran una ligera mejora en los resultados obtenidos al aplicar máscaras de ponderación y atención visual, los cuales aproximan los parámetros de calidad objetiva a la respuesta del ojo humano. ABSTRACT Video quality assessment is still a necessary tool for defining the criteria to characterize a signal with the viewing requirements imposed by the final user. New technologies, such as 3D stereoscopic video and formats of HD and beyond HD oblige to develop new analysis of video features for obtaining the highest user’s satisfaction. Among the problems detected during the process of this doctoral thesis, it has been determined that some phenomena affect to different phases in the audiovisual production chain, apart from the type of content. On first instance, the generation of contents process should be enough controlled through parameters that avoid the occurrence of visual discomfort in observer’s eye, and consequently, visual fatigue. It is especially necessary controlling sequences of stereoscopic 3D, with both animation and live-action contents. On the other hand, video quality assessment, related to compression processes, should be improved because some objective metrics are adapted to user’s perception. The use of psychovisual models and visual attention diagrams allow the weighting of image regions of interest, giving more importance to the areas which the user will focus most probably. These two work fields are related together through the definition of the term saliency. Saliency is the capacity of human visual system for characterizing an image, highlighting the areas which result more attractive to the human eye. Saliency in generation of 3DTV contents refers mainly to the simulated depth of the optic illusion, i.e. the distance from the virtual object to the human eye. On the other hand, saliency is not based on virtual depth, but on other features, such as motion, level of detail, position of pixels in the frame or face detection, which are the basic features that are part of the developed visual attention model, as demonstrated with tests. Extensive literature involving visual comfort assessment was looked up, and the development of new preliminary subjective assessment with users was performed, in order to detect the features that increase the probability of discomfort to occur. With this methodology, the conclusions drawn confirmed that one common source of visual discomfort was when an abrupt change of disparity happened in video transitions, apart from other degradations, such as window violation. New quality assessment was performed to quantify the distribution of disparities over different sequences. The results confirmed that abrupt changes in negative parallax environment produce accommodation-vergence mismatches derived from the increasing time for human crystalline to focus the virtual objects. On the other side, for developing metrics that adapt to human visual system, additional subjective tests were developed to determine the importance of each factor, which masks a concrete distortion. Results demonstrated slight improvement after applying visual attention to objective metrics. This process of weighing pixels approximates the quality results to human eye’s response.