Imaging properties of scanning equalization digital radiography: A simulation study

We have developed an empirically based simulation system to create images equivalent in SNR and SPR to those that would be acquired with various possible SEDR configurations. This system uses a collection of spot collimated full-field images (SCFFIs) of an anthropomorphic chest phantom, taken at high exposure levels and rescaled in noise and intensity, then digitally collimated and combined to produce the simulated SEDR images. This system allows for the study of design trade-offs between different equalization feedback schemes and scatter rejection geometries in addition to estimating the clinical benefits of SEDR over traditional imaging techniques. Data from this simulation system has demonstrated that SEDR techniques offer potential significant improvements over currently used digital radiography techniques for chest imaging. ^

Validity and reliability of using MVP 4 Function Walk4Life digital pedometers to assess physical activity levels among preschool-aged Head Start children

The Surgeon General recommends preschoolers 3-5 years old accumulate 60 minutes of moderate-to-vigorous physical activity (MVPA) per day. However, there is limited data measuring physical activity (PA) and MVPA amongst this population. The purpose of this cross-sectional study is to determine the validity, reliability, and feasibility of using MVP 4 Function Walk4Life digital pedometers (MVP-4) in measuring MVPA among preschoolers using the newly modified direct observational technique, System for Observing Fitness Instruction Time-Preschool Version (SOFIT-P) as the gold standard. An ethnically diverse population of 3-5 year old underserved children were recruited from two Harris County Department of Education (HCDE) Head Start centers. For 2 days at baseline and 2 days at post-test, 75 children enrolled wore MVP-4 pedometers for approximately 6-hours per observation day and were observed using SOFIT-P during predominantly active times. Statistical analyses used Pearson "r" correlation coefficients to determine mean minutes of PA and MVPA, convergent and criterion validity, and reliability. Significance was set at p = <0.05. Feasibility was determined through process evaluation information collected during this study via observations from data collectors and teacher input. Results show mean minutes of PA and MVPA ranged between 30-42 and 11-14 minutes, respectively. Convergent validity comparing BMI percentiles with MVP-4 PA outcomes show no significance at pre-test; however, each measurement at post-test showed significance for MVPA (p = 0.0247, p = 0.0056), respectively. Criterion validity comparing percent MVPA time between SOFIT-P and MVP-4 pedometers was determined; however, results deemed insufficient due to inconsistency in observation times while using the newly developed SOFIT-P. Reliability measures show no significance at pre-test, yet show significant results for all PA outcomes at post-test (p = 0.001, p = 0.001, p = 0.0010, p = 0.003), respectively. Finally, MVP-4 pedometers lacked feasibility due to logistical barriers in design. Researchers feel the significant results at post-test are secondary to increased familiarity and more accurate placement of pedometers across time. Researchers suggest manufacturers of MVP-4 pedometers further modify the instrument for ease of use with this population, following which future studies ought to determine validity using objective measures or all-day direct observation techniques.^

Modelo de organización de la información territorial : observatorio ambiental

La gestión del territorio no cuenta hasta el presente con una respuesta clara en cuanto a acciones a desarrollar para una concreta toma de decisiones. Para ello es necesario contar con información precisa y oportuna. Aquí los SIG se presentan como verdaderos sistemas de gestión en los que interactúan los componentes tecnológicos, organizacionales, metodológicos y estadísticos, que permiten elaborar planes de ordenamiento territorial y de manejo ambiental, monitorear la biodiversidad y construir indicadores ambientales. Su organización se basa en subsistemas tales como: • modelo de organización de la información espacial (que sustenta la plataforma SIG y de la Teledetección ), el que genera una base de datos relacional asociada a información contenida en el observatorio, representa cartográficamente los inicadores ambientales y el monitoreo de los mismos; • la metadata que incorpora las fuentes y datos vinculados a la documentación de datos geoespaciales digitales estandarizados y, por ultimo, • el modelo de monitoreo de la biodiversidad que conlleva a una serie de procesos tendientes especializar y analizar la dinámica presente en la cobertura vegetal a partir de imágenes del programa Landsat. El modelo involucra una integración de procesos apoyados en métodos científicos de teledetección y Sistemas de Información geográfica, permitiendo así el monitoreo para el diagnostico de estado actual de la cobertura marítima y terrestre, el análisis multitemporal, la espacialización y la transferencia de resultados. Un resultado directo de esta metodología es la detección de alertas tempranas.

Arte y nuevas tecnologías : acerca de la producción, modalidades expositivas y diversas aplicaciones de la imagen digital

Se propone la producción y posterior análisis de obras digitales que presenta una elaboración teórica-práctica intrínseca como sustento de las nuevas categorías y neologismos surgidos dentro del ámbito artístico digital. Se estudian distintas aplicaciones, modalidades de creación, exposición y transferencia al medio como así también las posibilidades relacionales que surgen entre imagen digital, objeto artístico y diseño de productos traspasando las fronteras de campos disciplinares como Arte y Diseño. La metodología empleada se concentra en enfoques sociológicos y semiótico-pragmáticos que permiten realizar un análisis profundo de las obras digitales en sí mismas y en relación a los contextos de producción, circulación, exposición y consumo.

Direct visualization of solute locations in laboratory ice samples, links to videos

Many important chemical reactions occur in polar snow, where solutes may be present in several reservoirs, including at the air-ice interface and in liquid-like regions within the ice matrix. Some recent laboratory studies suggest chemical reaction rates may differ in these two reservoirs. While investigations have examined where solutes are found in natural snow and ice, similar research has not identified solute locations in laboratory samples, nor the possible factors controlling solute segregation. To address this, we examined solute locations in ice samples prepared from either aqueous cesium chloride (CsCl) or Rose Bengal solutions that were frozen using several different methods. Samples frozen in a laboratory freezer had the largest liquid-like inclusions and air bubbles, while samples frozen in a custom freeze chamber had somewhat smaller air bubbles and inclusions; in contrast, samples frozen in liquid nitrogen showed much smaller concentrated inclusions and air bubbles, only slightly larger than the resolution limit of our images (~2 µm). Freezing solutions in plastic versus glass vials had significant impacts on the sample structure, perhaps because the poor heat conductivity of plastic vials changes how heat is removed from the sample as it cools. Similarly, the choice of solute had a significant impact on sample structure, with Rose Bengal solutions yielding smaller inclusions and air bubbles compared to CsCl solutions frozen using the same method. Additional experiments using higher-resolution imaging of an ice sample show that CsCl moves in a thermal gradient, supporting the idea that the solutes in ice are present in liquid-like regions. Our work shows that the structure of laboratory ice samples, including the location of solutes, is sensitive to freezing method, sample container, and solute characteristics, requiring careful experimental design and interpretation of results.

Digital surface model, hillshade and Lambertian reflectance model of the rock glaciers Oelgrube and Aeusseres Hochebenkar (Oetztal Alps, Tyrol, Austria)

With full-waveform (FWF) lidar systems becoming increasingly available from different commercial manufacturers, the possibility for extracting physical parameters of the scanned surfaces in an area-wide sense, as addendum to their geometric representation, has risen as well. The mentioned FWF systems digitize the temporal profiles of the transmitted laser pulse and of its backscattered echoes, allowing for a reliable determination of the target distance to the instrument and of physical target quantities by means of radiometric calibration, one of such quantities being the diffuse Lambertian reflectance. The delineation of glaciers is a time-consuming task, commonly performed manually by experts and involving field trips as well as image interpretation of orthophotos, digital terrain models and shaded reliefs. In this study, the diffuse Lambertian reflectance was compared to the glacier outlines mapped by experts. We start the presentation with the workflow for analysis of FWF data, their direct georeferencing and the calculation of the diffuse Lambertian reflectance by radiometric calibration; this workflow is illustrated for a large FWF lidar campaign in the Ötztal Alps (Tyrol, Austria), operated with an Optech ALTM 3100 system. The geometric performance of the presented procedure was evaluated by means of a relative and an absolute accuracy assessment using strip differences and orthophotos, resp. The diffuse Lambertian reflectance was evaluated at two rock glaciers within the mentioned lidar campaign. This feature showed good performance for the delineation of the rock glacier boundaries, especially at their lower parts.

Study of the fronts of Johnsons and Hurd Glaciers (Livingston Island, Antarctica) from 1957 to 2013, with links to shapefiles

The study of glacier fronts combines different geomatics measurement techniques as the classic survey using total station or theodolite, technical GNSS (Global Navigation Satellite System), using laser-scanner or using photogrammetry (air or ground). The measure by direct methods (classical surveying and GNSS) is useful and fast when accessibility to the glaciers fronts is easy, while it is practically impossible to realize, in the case of glacier fronts that end up in the sea (tide water glaciers). In this paper, a methodology that combines photogrammetric methods and other techniques for lifting the front of the glacier Johnsons, inaccessible is studied. The images obtained from the front, come from a non-metric digital camera; its georeferencing to a global coordinate system is performed by measuring points GNSS support in accessible areas of the glacier front side and applying methods of direct intersection in inaccessible points of the front, taking measurements with theodolite. The result of observations obtained were applied to study the temporal evolution (1957-2014) of the position of the Johnsons glacier front and the position of the Argentina, Las Palmas and Sally Rocks lobes front (Hurd glacier).

Digital image processing techniques as a tool for evaluating and mapping patinas on granite monuments

Monument conservation is related to the interaction between the original petrological parameters of the rock and external factors in the area where the building is sited, such as weather conditions, pollution, and so on. Depending on the environmental conditions and the characteristics of the materials used, different types of weathering predominate. In all, the appearance of surface crusts constitutes a first stage, whose origin can often be traced to the properties of the material itself. In the present study, different colours of “patinas” were distinguished by defining the threshold levels of greys associated with “pathology” in the histogram. These data were compared to background information and other parameters, such as mineralogical composition, porosity, and so on, as well as other visual signs of deterioration. The result is a map of the pathologies associated with “cover films” on monuments, which generate images by relating colour characteristics to desired properties or zones of interest.