2,690 research outputs found

    Monitoring and Predicting Air Quality in Ulaanbaatar, Mongolia Using IoT IoT

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    Air quality is a concern for people living all over the world. Pollutants in the air we breathe causes quality of life issues for everyone, particularly for those who are at risk, such as the very young, the elderly and those with lung disease. At very high levels, even healthy people suffer adverse effects. Ulaanbaatar, Mongolia is a city of a million and a half people, in Central Asia, surrounded by high hills. In the winter temperatures average below 0 degrees C from November to March, and most of the city is heated by coal. Beginning in 2015, the U.S. State Department has been monitoring the air quality at the US Embassy in Mongolia, and that data is available online through the Internet of Things, (IoT). Using this data we are seeking to use Extreme Value Analysis to predict future maximum levels of pollutants during the year, so that organizations within the country can plan appropriately. One of the benefits of continuous monitoring using IoT, is that data that in the past was difficult or extremely costly to get is becoming much more available. Because of this, one type of analysis that is becoming more common is Extreme Value Analysis, where statistics such as the maximums or minimums of samples are studied, as opposed to the more common analysis of mean averages. While a mean is often a very important measure of a population, it may not be the most interesting statistic. For example, when building a bridge over a river, the expected water level of the river is important, but far more important would be the expected highest water level over the next ten years, especially during periods of flooding. Likewise, when measuring levels of air pollution, the average level of pollution is important, but knowing when the highest and lowest levels of pollution during the day might be critical, especially for people in sensitive groups. The data that is available indicates strong seasonality, making the data set an excellent teaching tool for educators wanting to demonstrate statistical techniques necessary for handling such data, while the specific technique, Extreme Value Analysis, is quite appropriate to the study of pollution and other environmental issues

    IT Portfolio Management: A Case Study

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    IT Portfolio Management is increasingly becoming an important topic of research in IS/IT. The number of IT projects in a company can number in the hundreds, and it is difficult for upper level executives to manage this portfolio effectively without using some guiding methodology. This paper focuses on one such methodology that is being developed by a Fortune 100 company. Although many excellent papers have discussed using Real Options in the valuation of IT, there has been relatively little work in using Real Options in the IT Portfolio management context. Furthermore, most of the papers in the main IS journals have used relatively simple option models to evaluate (1) a single investment decision (2) assuming independence between projects. The focus of this paper is on a company that is actually managing IT portfolios of projects, and on some issues that may make exotic option models and more appropriate valuation tools

    Occasional essay: upper motor neuron syndrome in amyotrophic lateral sclerosis

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    The diagnosis of amyotrophic lateral sclerosis (ALS) requires recognition of both lower (LMN) and upper motor neuron (UMN) dysfunction.1 However, classical UMN signs are frequently difficult to identify in ALS.2 LMN involvement is sensitively detected by electromyography (EMG)3 but, as yet, there are no generally accepted markers for monitoring UMN abnormalities,4 the neurobiology of ALS itself, and disease spread through the brain and spinal cord,.5 Full clinical assessment is therefore necessary to exclude other diagnoses and to monitor disease progression. In part, this difficulty regarding detection of UMN involvement in ALS derives from the definition of ‘the UMN syndrome’. Abnormalities of motor control in ALS require reformulation within an expanded concept of the UMN, together with the neuropathological, neuro-imaging and neurophysiological abnormalities in ALS. We review these issues here

    A High Power Solar Electric Propulsion - Chemical Mission for Human Exploration of Mars

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    Recently Solar Electric Propulsion (SEP) as a main propulsion system has been investigated as an option to support manned space missions to near-Earth destinations for the NASA Gateway spacecraft. High efficiency SEP systems are able to reduce the amount of propellant long duration chemical missions require, ultimately reducing the required mass delivered to Low Earth Orbit (LEO) by a launch vehicle. However, for long duration interplanetary Mars missions, using SEP as the sole propulsion source alone may not be feasible due to the long trip times to reach and insert into the destination orbit. By combining an SEP propulsion system with a chemical propulsion system the mission is able to utilize the high-efficiency SEP for sustained vehicle acceleration and deceleration in heliocentric space and the chemical system for orbit insertion maneuvers and trans-earth injection, eliminating the need for long duration spirals. By capturing chemically instead of with low-thrust SEP, Mars stay time increases by nearly 200 days. Additionally, the size the of chemical propulsion system can be significantly reduced from that of a standard Mars mission because the SEP system greatly decreases the Mars arrival and departure hyperbolic excess velocities (V(sub infinity))

    Determination of Unfrozen Water in Winter Cereals at Subfreezing Temperatures

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    A Millisecond Interferometric Search for Fast Radio Bursts with the Very Large Array

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    We report on the first millisecond timescale radio interferometric search for the new class of transient known as fast radio bursts (FRBs). We used the Very Large Array (VLA) for a 166-hour, millisecond imaging campaign to detect and precisely localize an FRB. We observed at 1.4 GHz and produced visibilities with 5 ms time resolution over 256 MHz of bandwidth. Dedispersed images were searched for transients with dispersion measures from 0 to 3000 pc/cm3. No transients were detected in observations of high Galactic latitude fields taken from September 2013 though October 2014. Observations of a known pulsar show that images typically had a thermal-noise limited sensitivity of 120 mJy/beam (8 sigma; Stokes I) in 5 ms and could detect and localize transients over a wide field of view. Our nondetection limits the FRB rate to less than 7e4/sky/day (95% confidence) above a fluence limit of 1.2 Jy-ms. Assuming a Euclidean flux distribution, the VLA rate limit is inconsistent with the published rate of Thornton et al. We recalculate previously published rates with a homogeneous consideration of the effects of primary beam attenuation, dispersion, pulse width, and sky brightness. This revises the FRB rate downward and shows that the VLA observations had a roughly 60% chance of detecting a typical FRB and that a 95% confidence constraint would require roughly 500 hours of similar VLA observing. Our survey also limits the repetition rate of an FRB to 2 times less than any known repeating millisecond radio transient.Comment: Submitted to ApJ. 13 pages, 9 figure

    NASA GRC Compass Team Conceptual Point Design and Trades of a Hybrid Solar Electric Propulsion (SEP)/Chemical Propulsion Human Mars Deep Space Transport (DST) Vehicle

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    NASA has long been conducting studies which apply different in-space propulsion technology assumptions to the mission of sending humans to Mars. Two of the technologies under study that are considered to be the most near-term with respect to technology readiness level (TRL) are traditional chemical propulsion systems and high-power Solar Electric Propulsion (SEP) systems. The benefit of relatively low trip times inherent in using impulsive chemical propulsion systems to perform the full round-trip delta V is hampered by the large propellant mass required to perform these burns for human Mars missions. SEP systems offer the benefit of much lower propellant requirements to perform the same round-trip missions, at the cost of longer trip times. Traditionally, impulsive chemical systems are better suited than SEP when used in a gravity well, and SEP systems are more efficient than traditional impulsive systems when used in interplanetary space. A mission to Mars includes both of these scenarios, and thus several NASA architecture studies performed over the last few years have looked to combine the use of both SEP and chemical propulsion systems where they are the most beneficial to human Mars missions. This combined propulsion system concept has been referred to as a SEP/Chem hybrid Mars Transfer Vehicle and is currently shown as the concept Deep Space Transport (DST) in the March 2017 NASA presentation to the National Aerospace Council (NAC)

    Contamination of domestic groundwater systems by verotoxigenic escherichia coli (VTEC), 2003–2019: A global scoping review

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    peer-reviewedVerocytotoxin-producing E. coli (VTEC) are important agents of diarrhoeal disease in humans globally. As a noted waterborne disease, emphasis has been given to the study VTEC in surface waters, readily susceptible to microbial contamination. Conversely, the status of VTEC in potable groundwater sources, generally regarded as a “safe” drinking-water supply remains largely understudied. As such, this investigation presents the first scoping review seeking to determine the global prevalence of VTEC in groundwater supply sources intended for human consumption. Twenty-three peer-reviewed studies were identified and included for data extraction. Groundwater sample and supply detection rates (estimated 0.6 and 1.3%, respectively) indicate VTEC is infrequently present in domestic groundwater sources. However, where generic (fecal indicator) E. coli are present, the VTEC to E. coli ratio was found to be 9.9%, representing a latent health concern for groundwater consumers. Geographically, extracted data indicates higher VTEC detection rates in urban (5.4%) and peri–urban (4.9%) environments than in rural areas (0.9%); however, this finding is confounded by the predominance of research studies in lower income regions. Climate trends indicate local environments classified as ‘temperate’ (14/554; 2.5%) and ‘cold’ (8/392; 2%) accounted for a majority of supply sources with VTEC present, with similar detection rates encountered among supplies sampled during periods typically characterized by ‘high’ precipitation (15/649; 2.3%). Proposed prevalence figures may find application in preventive risk-based catchment and groundwater quality management including development of Quantitative Microbial Risk Assessments (QMRA). Notwithstanding, to an extent, a large geographical disparity in available investigations, lack of standardized reporting, and bias in source selection, restrict the transferability of research findings. Overall, the mechanisms responsible for VTEC transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between hydrogeological and public health research. Key recommendations and guidelines are provided for prospective studies directed at increasingly integrative and multi-disciplinary research
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