12,338 research outputs found

    Performance, physiological, and oculometer evaluation of VTOL landing displays

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    A methodological approach to measuring workload was investigated for evaluation of new concepts in VTOL aircraft displays. Physiological, visual response, and conventional flight performance measures were recorded for landing approaches performed in the NASA Visual Motion Simulator (VMS). Three displays (two computer graphic and a conventional flight director), three crosswind amplitudes, and two motion base conditions (fixed vs. moving base) were tested in a factorial design. Multivariate discriminant functions were formed from flight performance and/or visual response variables. The flight performance variable discriminant showed maximum differentation between crosswind conditions. The visual response measure discriminant maximized differences between fixed vs. motion base conditions and experimental displays. Physiological variables were used to attempt to predict the discriminant function values for each subject/condition trial. The weights of the physiological variables in these equations showed agreement with previous studies. High muscle tension, light but irregular breathing patterns, and higher heart rate with low amplitude all produced higher scores on this scale and thus represent higher workload levels

    Build a Miracle: Building Homes and Building Relationships – A Community Perspective

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    The purpose of this research was to look at how community support can facilitate the transformation of an impoverished neighborhood, through the case study of the nonprofit Build A Miracle (BAM) in the community of El Florido in Tijuana, Mexico. Mexico is a country that has long struggled with income inequality and high poverty rates (Martínez, 2003). There are many organizations that are involved with charitable work in Mexico, each with its own goals and approaches (e.g. Habitat for Humanity Mexico; Christian Base Communities – CBCs). BAM is a San Diego-based nonprofit organization that has built over 270 homes and provided dozens of educational scholarships for people living in poverty in Tijuana. Through the narrative of eleven women from El Florido, I examined the impact that BAM has had on an economically struggling community. This involved interviewing female community leaders about their experiences working with BAM and their outlook on how their lives and community have changed since BAM’s arrival. This investigation brought to light that one of the integral components of BAM’s model is the fostering of relationships between the American volunteers and the Mexican families in addition to traditional monetary support. The data also suggest that the strong Mexican female leaders have played a crucial role in the operation of the organization

    Assessment of different urban traffic control strategy impacts on vehicle emissions

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    This paper investigates the influence of traffic signal control strategy on vehicle emissions, vehicle journey time and total throughput flow within a single isolated four-armed junction. Two pre-timed signal plans are considered, one with two-stages involving permissive-only opposing turns and the other with four-stages which has no conflicting traffic. Additionally, the increase in efficiency by utilising actuated signal timing where green time is re-optimised as flow values vary is investigated. A microscopic traffic simulation model is used to model flows and AIRE (Analysis of Instantaneous Road Emissions) microscopic emissions model is utilised to out- put emission levels from the flow data. A simple junction model shows that the two-stage signal plan is more efficient in both emis- sions and journey time. However, as the level of opposed turning vehicles and conflicting movement increases, the two-stage model moves to being the inferior signal plan choice and the four-stage plan outputs fewer emissions than the two-stage plan. A real-world example of a four-armed junction has been used in this study and from the traffic survey data and existing junction layout; it is rec- ommended that a two-stage plan is used as it produces lower amounts of emissions and shorter journey times compared to a four-stage plan. The results also show that nitrogen oxides (NOx) are the most sensitive to changes in flow followed by carbon dioxide (CO2), Black Carbon and then particulate matter (PM10)

    Which SMEs seek external support? Business characteristics, management behaviour and external influences in a contingency approach

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    To improve SME growth and competitiveness, governments often encourage business owner-managers to make use of external sources of support. Whether they seek this depends on the degree to which they perceive themselves to need assistance. Additionally its use can be constrained by market failures. In this paper, we model whether SME owner-managers seek information and advice from formal sources, including public and private providers. In 2011, the researchers conducted a telephone survey of 1202 SMEs (1-249 employees) in England to assess the use and non-use of external support between 2008 and 2011. Using a contingency approach, we model various influences on the use and non-use of formal support and identify those owner-managers who face more concerns but have less confidence in their capabilities. We find the demand for support, especially from private providers, is fuelled by a firm’s objective to grow and a size threshold, although this is moderated by various concerns which increase the likelihood of using public sources. The willingness to take informal advice can act as a stepping stone to using formal sources. Whilst market failures affected less than a fifth of firms, those with women directors were particularly affected as were newly founded firms

    Empirical constraints on vacuum decay in the stringy landscape

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    It is generally considered as self evident that the lifetime of our vacuum in the landscape of string theory cannot be much shorter than the current age of the universe. Here I show why this lower limit is invalid. A certain type of ``parallel universes'' is a necessary consequence of the string-landscape dynamics and might well allow us to ``survive'' vacuum decay. As a consequence our stringy vacuum's lifetime is empirically unconstrained and could be very short. Based on this counter-intuitive insight I propose a novel type of laboratory experiment that searches for an apparent violation of the quantum-mechanical Born rule by gravitational effects on vacuum decay. If the lifetime of our vacuum should turn out to be shorter than 6 x 10^{-13} seconds such an experiment is sufficiently sensitive to determine its value with state-of-the-art equipment.Comment: 13 pages, 2 figures, proposes a laboratory experimen

    Impact of traffic management on black carbon emissions: a microsimulation study

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    This paper investigates the effectiveness of traffic management tools, includ- ing traffic signal control and en-route navigation provided by variable message signs (VMS), in reducing traffic congestion and associated emissions of CO2, NOx, and black carbon. The latter is among the most significant contributors of climate change, and is associated with many serious health problems. This study combines traffic microsimulation (S-Paramics) with emission modeling (AIRE) to simulate and predict the impacts of different traffic management measures on a number traffic and environmental Key Performance Indicators (KPIs) assessed at different spatial levels. Simulation results for a real road network located in West Glasgow suggest that these traffic management tools can bring a reduction in travel delay and BC emission respectively by up to 6 % and 3 % network wide. The improvement at local levels such as junctions or corridors can be more significant. However, our results also show that the potential benefits of such interventions are strongly dependent on a number of factors, including dynamic demand profile, VMS compliance rate, and fleet composition. Extensive discussion based on the simulation results as well as managerial insights are provided to support traffic network operation and control with environmental goals. The study described by this paper was conducted under the support of the FP7-funded CARBOTRAF project

    Pregnancy without ovarian function A case report

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    A 38-year-old nulliparous woman suffering from premature menopause was stimulated with oestradiol valerate in order to create an artificial endometrial cycle. Three oocytes were donated by a woman on an in vitro fertilisation cycle and were inseminated with the patient's husband's sperm. These were then transferred into the patient's uterus after the endometrium had been primed with progesterone to change it to the secretory phase. Pregnancy resulted and proceeded well. Gestation was terminated at the 34th week by caesarean section and 2 healthy boys and 1 girl were delivered
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