789 research outputs found
The Tangled Web: Studying Online Fake News
Fake news has become a ubiquitous and extremely worrying phenomenon, capturing the attention of academics, governments, businesses, media, and the general public. Despite this notoriety, many questions remain to be answered about the generation, diffusion, consumption, and impacts of fake news that are spread through social media and online communities. A nascent body of IS research is emerging that addresses some of these questions. In this panel, we aim to motivate further IS research and produce an agenda by highlighting some of the important issues that need to be discussed with regard to fake news. We examine how IS scholarship can address these issues by drawing on its existing body of knowledge as well as considering less-studied but potentially fruitful areas of research
Dealing and sharing : the construction of community in a Pretoria public park
This paper describes how a group of men, who are invisible to the state because they possess
no formal legal documentation, such as ID books or passports, and do not take part in the
formal economy, live in a public park in Gezina, Pretoria. It explores how they negotiate
some of the ambiguities of street life and community through acts of sharing and illegal public
gambling. While the moral and economic principles organising life in the park are plural, forms
of everyday communism predominate. I argue that this predominance allows for a form of
community that allows the men living there to navigate their daily uncertainties more easily, and
explore the ways in which public gambling functions to maintain the conditions for constructive
relations amongst them.http://www.tandfonline.com/loi/rasa20hb2016Anthropology and Archaeolog
Sub-arcsec X-Ray Telescope for Imaging The Solar Corona In the 0.25 - 1.2 keV Band
We have developed an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype X-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degee graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 sq cm at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the X-ray telescope's response to the Sun show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight
Formal Verification of Astronaut-Rover Teams for Planetary Surface Operations
This paper describes an approach to assuring the reliability of autonomous systems for Astronaut-Rover (ASRO) teams using the formal verification of models in the Brahms multi-agent modelling language. Planetary surface rovers have proven essential to several manned and unmanned missions to the moon and Mars. The first rovers were tele- or manuallyoperated, but autonomous systems are increasingly being used to increase the effectiveness and range of rover operations on missions such as the NASA Mars Science Laboratory. It is anticipated that future manned missions to the moon and Mars will use autonomous rovers to assist astronauts during extravehicular activity (EVA), including science, technical and construction operations. These ASRO teams have the potential to significantly increase the safety and efficiency of surface operations. We describe a new Brahms model in which an autonomous rover may perform several different activities including assisting an astronaut during EVA. These activities compete for the autonomous rovers āattentionā and therefore the rover must decide which activity is currently the most important and engage in that activity. The Brahms model also includes an astronaut agent, which models an astronauts predicted behaviour during an EVA. The rover must also respond to the astronauts activities. We show how this Brahms model can be simulated using the Brahms integrated development environment. The model can then also be formally verified with respect to system requirements using the SPIN model checker, through automatic translation from Brahms to PROMELA (the input language for SPIN). We show that such formal verification can be used to determine that mission- and safety critical operations are conducted correctly, and therefore increase the reliability of autonomous systems for planetary rovers in ASRO teams
AsteroidX: An Asteroid Exploration Simulation and Visualisation Tool
The use of multi-agent robotics for space exploration creates the need for verification and validation using formal methods and simulation-based testing of such systems. This paper presents an asteroid exploration simulation and visualisation tool that can facilitate agent research in an approximated space setting. The software is able to simulate and visualise multiple spacecrafts navigating a customisable asteroid field environment under the control of either user or agent commands and abiding to space physics constraints. A built-in autopilot system implements Lambertās algorithm to allow autonomous orbital entry/transfer manoeuvres, and collision-free long-range path-finding if the objective is distant. A simulated scenario is described, involving two agents observing multiple asteroids during a debris strike
Assessing Retinal Structure In Complete Congenital Stationary Night Blindness and Oguchi Disease
Purpose To examine retinal structure and changes in photoreceptor intensity after dark adaptation in patients with complete congenital stationary night blindness and Oguchi disease. Design Prospective, observational case series. Methods We recruited 3 patients with complete congenital stationary night blindness caused by mutations in GRM6, 2 brothers with Oguchi disease caused by mutations in GRK1, and 1 normal control. Retinal thickness was measured from optical coherence tomography images. Integrity of the rod and cone mosaic was assessed using adaptive optics scanning light ophthalmoscopy. We imaged 5 of the patients after a period of dark adaptation and examined layer reflectivity on optical coherence tomography in a patient with Oguchi disease under light- and dark-adapted conditions. Results Retinal thickness was reduced in the parafoveal region in patients with GRM6 mutations as a result of decreased thickness of the inner retinal layers. All patients had normal photoreceptor density at all locations analyzed. On removal from dark adaptation, the intensity of the rods (but not cones) in the patients with Oguchi disease gradually and significantly increased. In 1 Oguchi disease patient, the outer segment layer contrast on optical coherence tomography was 4-fold higher under dark-adapted versus light-adapted conditions. Conclusions The selective thinning of the inner retinal layers in patients with GRM6 mutations suggests either reduced bipolar or ganglion cell numbers or altered synaptic structure in the inner retina. Our finding that rods, but not cones, change intensity after dark adaptation suggests that fundus changes in Oguchi disease are the result of changes within the rods as opposed to changes at a different retinal locus
Key Data Gaps for Understanding Trends in Prescription Opioid Analgesic Abuse and Diversion Among Chronic Pain Patients and Nonmedical Users
Population dynamics of medical and nonmedical prescription opioid usage and adverse outcomes were modeled. Critical parameter values were determined by their amount of influence on model behavior. Results suggest that closing these data gaps would help researchers to better identify ways to reduce the risk of adverse outcomes
Highly purified human-derived follicle-stimulating hormone (BravelleĀ®) has equivalent efficacy to follitropin-beta (Follistim Ā®) in infertile women undergoing in vitro fertilization
BACKGROUND: These data compare the efficacy and safety of highly purified human-derived follicle-stimulating hormone (Bravelle(R)) and recombinant follitropin-Ī² (Follistim(R)) in women undergoing in vitro fertilization. METHODS: This report describes the pooled data from two, nearly identical, randomized, controlled, parallel-group, multicenter studies conducted in a total of 19 academic and private IVF-ET centers in the United States. Infertile premenopausal women underwent pituitary down-regulation using leuprolide acetate followed by a maximum of 12 days of subcutaneous Bravelle(R) (n = 120) or Follistim(R) (n = 118), followed by administration of human chorionic gonadotropin, oocyte retrieval and embryo transfer. The primary efficacy measure was the mean number of oocytes retrieved; secondary efficacy measures included the total dose and duration of gonadotropin treatment; peak serum estradion levels; embryo transfer and implantation rates; chemical, clinical and continuing pregnancies; and live birth rates. All adverse events were recorded and injection site pain was recorded daily using a patient, self-assessment diary. RESULTS: Similar efficacy responses were observed for all outcome parameters in the two treatment groups. Although patients receiving Bravelle(R) consistently reported a greater number of chemical, clinical and continuing pregnancies, as well as an increased rate of live birth, the data did not attain statistical significance (P > 0.05). The overall incidence of adverse events was similar in both groups, but compared to Follistim(R), injections of Bravelle(R) were reported by patients to be significantly less painful (P < 0.001). CONCLUSIONS: Bravelle(R) and Follistim(R) had comparable efficacy in controlled ovarian hyperstimulation in women undergoing IVF-ET. There were no differences in the nature or number of adverse events between the treatment groups although Bravelle(R) injections were reported to be significantly less painful
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