1,061 research outputs found
Satellite data for surface-mine inventory
To determine the feasibility of satellite data for surface-mine inventory, particularly as it applies to coal, a case study was conducted in Maryland. A band-ratio method was developed to measure disturbed surface areas, and it proved to be extendible both temporally and geographically. This method was used to measure area changes in the region over three time periods from September 1972 through July 1974 and to map the entire two-county area for 1973. For mines ranging between 31 and 244 acres (12 to 98 hectares) the measurement accuracy of total affected acreage was determined to be 92%. Mines of 120 acres (50 hectares) and larger were measured with greater accuracy, some within one percent of the actual area. The ability to identify, classify, and measure strip-mine surfaces in a two-county area (1,541 square kilometers - 595 square miles) of western Maryland was demonstrated through the use of computer processing. On the basis of these results the use of LANDSAT satellite data and multilevel sampling of aircraft and field verification inspections, multispectral analysis of digital data is shown to be an effective, rapid, and accurate means of monitoring the surface mining cycle
Exploring Planets with Directed Aerial Robot Explorers
Global Aerospace Corporation (GAC) is developing a revolutionary system architecture for exploration of planetary atmospheres and surfaces from atmospheric altitudes. The work is supported by the NASA Institute for Advanced Concepts (NIAC). The innovative system architecture relies upon the use of Directed Aerial Robot Explorers (DAREs), which essentially are long-duration-flight autonomous balloons with trajectory control capabilities that can deploy swarms of miniature probes over multiple target areas. Balloon guidance capabilities will offer unprecedented opportunities in high-resolution, targeted observations of both atmospheric and surface phenomena. Multifunctional microprobes will be deployed from the balloons once over the target areas, and perform a multitude of functions, such as atmospheric profiling or surface exploration, relaying data back to the balloons or an orbiter. This architecture will enable low-cost, low-energy, long-term global exploration of planetary atmospheres and surfaces. This paper focuses on a conceptual analysis of the DARE architecture capabilities and science applications for Venus, Titan and Jupiter. Preliminary simulations with simplified atmospheric models show that a relatively small trajectory control wing can enable global coverage of the atmospheres of Venus and Titan by a single balloon over a 100-day mission. This presents unique opportunities for global in situ sampling of the atmospheric composition and dynamics, atmospheric profiling over multiple sites with small dropsondes and targeted deployment of surface microprobes. At Jupiter, path guidance capabilities of the DARE platforms permits targeting localized regions of interest, such as "hot spots" or the Great Red Spot. A single DARE platform at Jupiter can sample major types of the atmospheric flows (zones and belts) over a 100-day mission. Observations by deployable probes would reveal if the differences exist in radiative, dynamic and compositional environments at these sites
Bregman Voronoi Diagrams: Properties, Algorithms and Applications
The Voronoi diagram of a finite set of objects is a fundamental geometric
structure that subdivides the embedding space into regions, each region
consisting of the points that are closer to a given object than to the others.
We may define many variants of Voronoi diagrams depending on the class of
objects, the distance functions and the embedding space. In this paper, we
investigate a framework for defining and building Voronoi diagrams for a broad
class of distance functions called Bregman divergences. Bregman divergences
include not only the traditional (squared) Euclidean distance but also various
divergence measures based on entropic functions. Accordingly, Bregman Voronoi
diagrams allow to define information-theoretic Voronoi diagrams in statistical
parametric spaces based on the relative entropy of distributions. We define
several types of Bregman diagrams, establish correspondences between those
diagrams (using the Legendre transformation), and show how to compute them
efficiently. We also introduce extensions of these diagrams, e.g. k-order and
k-bag Bregman Voronoi diagrams, and introduce Bregman triangulations of a set
of points and their connexion with Bregman Voronoi diagrams. We show that these
triangulations capture many of the properties of the celebrated Delaunay
triangulation. Finally, we give some applications of Bregman Voronoi diagrams
which are of interest in the context of computational geometry and machine
learning.Comment: Extend the proceedings abstract of SODA 2007 (46 pages, 15 figures
Focused Solar Ablation: A Nanosat-Based Method for Active Removal of Space Debris
A novel concept for the active removal of space debris using solar power is proposed. Focused solar ablation is an in-space propulsion concept based on using concentrator mirrors on nanosats and using the solar power to evaporate material from the debris to produce deceleration thrust thereby providing the âV necessary to deorbit. An energy balance is used along with free-molecular effusion theory to estimate the thrust produced by the concept and the corresponding deorbit times for an aluminum debris masses of 10 kg and 0.27 kg for various concentrator mirror areas and the diameter of the spot on which the solar power is concentrated. The analysis shows that the deorbit times of a few hours for both masses showing that the method is attractive for active space debris removal. Experiments performed using electron beams to evaporate aluminum in a vacuum chamber show that the method is also practically feasible to deorbit space debris using solar power available in low earth orbit (LEO)
Microfluidic Platform to Study Electric Field Based Root Targeting by Pathogenic Zoospores
This paper reports the fabrication and application of a
microfluidic Lab-on-a-Chip platform to study the
electrotactic movements of pathogenic microorganisms.
The movement of the pathogens in response to electric
fields are one way in which they are thought to locate their
hosts. Design and fabrication of the platform, and
associated micro-electronics are described. The platform
contains arrays of micro-electrodes that generate an electric
field of defined strength in a micro-chamber into which
feed inlet and outlet channels for entry and exit of media
and microorganisms. To demonstrate applicability of the
platform, motile zoospores of the pathogenic oomycete
Phytophthora nicotianae were seeded in the inlet and a
voltage was applied to investigate the electrotactic
responses of the zoospores. This platform offers a unique
opportunity to study electrotactic movements that may be
responsible for the ability of the pathogens to locate and
invade host tissue
Mars Exploration with Directed Aerial Robot Explorers
Global Aerospace Corporation (GAC) is developing a revolutionary system architecture for exploration of planetary atmospheres and surfaces from atmospheric altitudes. The work is supported by the NASA Institute for Advanced Concepts (NIAC). The innovative system architecture relies upon the use of Directed Aerial Robot Explorers (DAREs), which essentially are longâdurationâflight autonomous balloons with trajectory control capabilities that can deploy swarms of miniature probes over multiple target areas. Balloon guidance capabilities will offer unprecedented opportunities in highâresolution, targeted observations of both atmospheric and surface phenomena. Multifunctional microprobes will be deployed from the balloons when over the target areas, and perform a multitude of functions, such as atmospheric profiling or surface exploration, relaying data back to the balloons or an orbiter. This architecture will enable lowâcost, lowâenergy, longâterm global exploration of planetary atmospheres and surfaces. A conceptual analysis of DARE capabilities and science applications for Mars is presented. Initial results of simulations indicate that a relatively small trajectory control wing can significantly change planetary balloon flight paths, especially during summer seasons in Polar Regions. This opens new possibilities for highâresolution observations of crustal magnetic anomalies, polar layered terrain, polar clouds, dust storms at the edges of the Polar caps and of seasonal variability of volatiles in the atmosphere
Tracing The Sound Horizon Scale With Photometric Redshift Surveys
We propose a new method for cosmological parameters extraction using the
baryon acoustic oscillation scale as a standard ruler in deep galaxy surveys
with photometric determination of redshifts. The method consists in a simple
empirical parametric fit to the angular 2-point correlation function w(theta).
It is parametrized as a power law to describe the continuum plus a Gaussian to
describe the BAO bump. The location of the Gaussian is used as the basis for
the measurement of the sound horizon scale. This method, although simple,
actually provides a robust estimation, since the inclusion of the power law and
the use of the Gaussian removes the shifts which affect the local maximum. We
discuss the effects of projection bias, non-linearities, redshift space
distortions and photo-z precision, and apply our method to a mock catalog of
the Dark Energy Survey, built upon a large N-body simulation provided by the
MICE collaboration. We discuss the main systematic errors associated to our
method and show that they are dominated by the photo-z uncertainty.Comment: 12 pages, 12 figures, published online in MNRAS, 25 October 201
Creating a FACETS digital toolkit to promote quality of life of people with multiple sclerosis through Participatory Design
In this paper, we report on the first stages of creating a stand-alone digital toolkit focusing on the
homework elements of FACETS (Fatigue: Applying Cognitive behavioural and Energy effectiveness
Techniques to lifeStyle). FACETS is an evidence-based face-to-face fatigue management group
programme for people with multiple sclerosis. This paper details the participatory design process
from requirements elicitation to initial prototyping and how offline activities linked to each session
have been mapped in the digitised solution (mobile app)
Non-suicidal self-injury (Nssi) in adolescent inpatients: assessing personality features and attitude toward death
<p>Abstract</p> <p>Background</p> <p>Non-suicidal self-injury (NSSI) is a common concern among hospitalized adolescents, and can have significant implications for short and long-term prognosis. Little research has been devoted on how personality features in severely ill adolescents interact with NSSI and "attitude toward life and death" as a dimension of suicidality. Developing more specific assessment methodologies for adolescents who engage in self-harm without suicidal intent is relevant given the recent proposal of a non-suicidal self-injury (NSSI) disorder and may be useful in predicting risk in psychiatrically impaired subjects.</p> <p>Methods</p> <p>Consecutively hospitalized adolescents in a psychiatric unit (N = 52; 71% females; age 12-19 years), reporting at least one recent episode of self-harm according to the <it>Deliberate Self-harm Inventory</it>, were administered the <it>Structured Clinical Interview for DSM Mental Disorders and Personality Disorders (SCID I and II)</it>, the <it>Children's Depression Inventory </it>and the <it>Multi-Attitude Suicide Tendency Scale (MAST)</it>.</p> <p>Results</p> <p>Mean age onset of NSSI in the sample was 12.3 years. All patients showed "repetitive" NSSI (high frequency of self-harm), covering different modalities. Results revealed that 63.5% of adolescents met criteria for Borderline Personality Disorder (BPD) and that the rest of the sample also met criteria for personality disorders with dysregulated traits. History of suicide attempts was present in 46.1% of cases. Elevated depressive traits were found in 53.8%. Results show a statistically significant negative correlation between the score on the "Attraction to Life" subscale of the MAST and the <it>frequency </it>and <it>diversification </it>of self-harming behaviors.</p> <p>Conclusions</p> <p>Most adolescent inpatients with NSSI met criteria for emotionally dysregulated personality disorders, and showed a reduced "attraction to life" disposition and significant depressive symptoms. This peculiar psychopathological configuration must be addressed in the treatment of adolescent inpatients engaging in NSSI and taken into account for the prevention of suicidal behavior in self-injuring adolescents who do not exhibit an explicit intent to die.</p
Developing an Optical Microlever for Stable and Unsupported Force Amplification
â Optical micromachines have the potential to im prove the capabilities of optical tweezers by amplifying forces
and allowing for indirect handling and probing of specimens.
However, systematic design and testing of micromachine per formance is still an emerging field. In this work we have
designed and tested an unsupported microlever, suitable for
general-purpose optical tweezer studies, that demonstrates
stable trapping performance and repeatable doubling of applied
forces. Stable trapping was ensured by analysing images to
monitor focus shift when levers oscillated repeatedly, before
the best-performing design was selected for force amplification.
This study also shows that direct measurement of trap stiffness
using the equipartition theorem appears to be a valid method
for measuring applied forces on the spherical handles of
microlevers
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