1,667 research outputs found

    Changes in the Greenland Ice Sheet of the Southeastern Maniitsoq Coast from 1994-2004 and 2009-2019

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    Remote sensing mechanisms through the use of technology like the Landsat 5-7 Land Manager satellites are commonly used in conjunction with multispectral methods such as unsupervised classification to record and analyze changes in snow and ice over time in areas such as the Greenland Ice Sheet (GrIS). Unsupervised classification is a method of identifying, grouping, and labeling features in an image according to their spectral values and is therefore a good method of classifying snow and ice in areas such as Greenland. The goal of unsupervised classifications is to assign pixels into potentially meaningful subsurface classes based on similarities of geophysical responses, in order to create a final product that displays an accurate class map of the land cover of the area (Kvamme, 2019). Within the southwestern region of Greenland is the town Maniitsoq along the (GrIS) that is surrounded by natural canal-like channels and located in the Qeqqata municipality. The southwestern Maniitsoq Greenland territory lies within the northernmost area south of the Arctic Circle and contains big, long, and deep glaciers. Temperatures in southern Greenland do not exceed 20 °C within the summer months of June, July, or August. Greenland is warmest and driest on land closest to the ice sheet during these summer months (Topas Travel, 2019). The location of our study area, the southwestern region of Greenland near Maniitsoq, was captured with Landsat imagery. The ice land cover was classified into three different sectional groups: changed snow/ice, unchanged snow/ice, and other. The research question of this project is as follows: how have the Greenland Ice Sheet glaciers along the eastern coast and inland Greenland changed from June through August of 1994-2004 and 2009-2019

    Attenuation measurements in artificial clouds Final technical report

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    Attenuation and near-forward scattering of both ice and water fogs and dependence of spectral curves of transmittance on particle size distributio

    Air Traffic Management Blockchain Infrastructure for Security, Authentication, and Privacy

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    Current radar-based air traffic service providers may preserve privacy for military and corporate operations by procedurally preventing public release of selected flight plans, position, and state data. The FAA mandate for national adoption of Automatic Dependent Surveillance Broadcast (ADS-B) in 2020 does not include provisions for maintaining these same aircraft-privacy options, nor does it address the potential for spoofing, denial of service, and other well-documented risk factors. This paper presents an engineering prototype that embodies a design and method that may be applied to mitigate these ADS-B security issues. The design innovation is the use of an open source permissioned blockchain framework to enable aircraft privacy and anonymity while providing a secure and efficient method for communication with Air Traffic Services, Operations Support, or other authorized entities. This framework features certificate authority, smart contract support, and higher-bandwidth communication channels for private information that may be used for secure communication between any specific aircraft and any particular authorized member, sharing data in accordance with the terms specified in the form of smart contracts. The prototype demonstrates how this method can be economically and rapidly deployed in a scalable modular environment

    Augmented Reality Tower Technology Assessment

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    Augmented Reality technology may help improve Air Traffic Control Tower efficiency and safety during low-visibility conditions. This paper presents the assessments of five off-duty controllers who shadow-controlled' with an augmented reality prototype in their own facility. Initial studies indicated unanimous agreement that this technology is potentially beneficial, though the prototype used in the study was not adequate for operational use. Some controllers agreed that augmented reality technology improved situational awareness, had potential to benefit clearance, control, and coordination tasks and duties and could be very useful for acquiring aircraft and weather information, particularly aircraft location, heading, and identification. The strongest objections to the prototype used in this study were directed at aircraft registration errors, unacceptable optical transparency, insufficient display performance in sunlight, inadequate representation of the static environment and insufficient symbology

    Negligence—Doctrine of Macpherson v. Buick—Liability of Remote Supplier

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    La Rocca v. Farrington, 301 N.Y. 247, 93 N.E. 2d 829 (1950)

    Locomotor adaptability in persons with unilateral transtibial amputation

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    Background Locomotor adaptation enables walkers to modify strategies when faced with challenging walking conditions. While a variety of neurological injuries can impair locomotor adaptability, the effect of a lower extremity amputation on adaptability is poorly understood. Objective Determine if locomotor adaptability is impaired in persons with unilateral transtibial amputation (TTA). Methods The locomotor adaptability of 10 persons with a TTA and 8 persons without an amputation was tested while walking on a split-belt treadmill with the parallel belts running at the same (tied) or different (split) speeds. In the split condition, participants walked for 15 minutes with the respective belts moving at 0.5 m/s and 1.5 m/s. Temporal spatial symmetry measures were used to evaluate reactive accommodations to the perturbation, and the adaptive/de-adaptive response. Results Persons with TTA and the reference group of persons without amputation both demonstrated highly symmetric walking at baseline. During the split adaptation and tied post-adaptation walking both groups responded with the expected reactive accommodations. Likewise, adaptive and de-adaptive responses were observed. The magnitude and rate of change in the adaptive and de-adaptive responses were similar for persons with TTA and those without an amputation. Furthermore, adaptability was no different based on belt assignment for the prosthetic limb during split adaptation walking. Conclusions Reactive changes and locomotor adaptation in response to a challenging and novel walking condition were similar in persons with TTA to those without an amputation. Results suggest persons with TTA have the capacity to modify locomotor strategies to meet the demands of most walking conditions despite challenges imposed by an amputation and use of a prosthetic limb

    Soft systems methodology: a context within a 50-year retrospective of OR/MS

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    Soft systems methodology (SSM) has been used in the practice of operations research and management science OR/MS) since the early 1970s. In the 1990s, it emerged as a viable academic discipline. Unfortunately, its proponents consider SSM and traditional systems thinking to be mutually exclusive. Despite the differences claimed by SSM proponents between the two, they have been complementary. An extensive sampling of the OR/MS literature over its entire lifetime demonstrates the richness with which the non-SSM literature has been addressing the very same issues as does SSM

    Cooperative action in eukaryotic gene regulation: physical properties of a viral example

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    The Epstein-Barr virus (EBV) infects more than 90% of the human population, and is the cause of several both serious and mild diseases. It is a tumorivirus, and has been widely studied as a model system for gene (de)regulation in human. A central feature of the EBV life cycle is its ability to persist in human B cells in states denoted latency I, II and III. In latency III the host cell is driven to cell proliferation and hence expansion of the viral population, but does not enter the lytic pathway, and no new virions are produced, while the latency I state is almost completely dormant. In this paper we study a physico-chemical model of the switch between latency I and latency III in EBV. We show that the unusually large number of binding sites of two competing transcription factors, one viral and one from the host, serves to make the switch sharper (higher Hill coefficient), either by cooperative binding between molecules of the same species when they bind, or by competition between the two species if there is sufficient steric hindrance.Comment: 7 pages, 6 figures, 1 tabl
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