184 research outputs found

    Analog of the Clauser-Horne-Shimony-Holt inequality for steering

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    The Clauser-Horne-Shimony-Holt (CHSH) inequality (and its permutations), are necessary and sufficient criteria for Bell nonlocality in the simplest Bell-nonlocality scenario: 2 parties, 2 measurements per party and 2 outcomes per measurement. Here we derive an inequality for EPR-steering that is an analogue of the CHSH, in that it is necessary and sufficient in this same scenario. However, since in the case of steering the device at Bob's site must be specified (as opposed to the Bell case in which it is a black box), the scenario we consider is that where Alice performs two (black-box) dichotomic measurements, and Bob performs two mutually unbiased qubit measurements. We show that this inequality is strictly weaker than the CHSH, as expected, and use it to decide whether a recent experiment [Phys. Rev. Lett. 110, 130401 (2013).] involving a single-photon split between two parties has demonstrated EPR-steering.Comment: Expanded v2, new results, new figure. 9 pages, 2 figure

    Simulation of Shade Tree Effects on Residential Energy Consumption in Four U.S. Cities

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    Strategically placed trees can modify urban temperatures by casting shade and thus affect energy consumption for residential cooling and heating. Energy conservation benefits are influenced by the quantity as well as the quality of tree shade upon building surfaces. In this study, we employed an energy simulation program called EnergyPlus as a means to evaluate the effect of a single shade tree upon a structure model having a floor area of 200 m2 in four U.S. cities. Results of EnergyPlus simulations with various single tree planting configurations showed that a large tree on the west aspect of a structure could decrease annual energy costs by up to 160 kWh (valued at 18)insoutherncitieswithlongercoolingseasons.Whereas,thesametreeonthesouthaspectcouldincreaseannualenergycostsbyupto134kWh(−18) in southern cities with longer cooling seasons. Whereas, the same tree on the south aspect could increase annual energy costs by up to 134 kWh (−15) in northern cities with longer heating seasons. In addition to tree placement around the structure, interactions between sun angle, tree form, and tree distance were observed to influence the effects on energy consumption. Understanding the fundamental interactions between tree form, tree placement, and geographic settings, which influence both the quantity and quality of shade provision, is critical for improving energy conservation benefits of trees in urban settings

    Trees on K-12 School Campuses in Virginia

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    Trees and saplings growing on K-12 school campuses were investigated in 105 school districts across Virginia. There were 2812 trees (\u3e12.5 cm stem diameter at 1.4 m above ground level) inventoried across all campuses. The mean and median campus tree population was 27 and 18, respectively. Loblolly pine (Pinus taeda L.) was the most abundant species, accounting for 11% of all inventoried trees. Red maple (Acer rubrum L.) was the most frequently inventoried species, present on 44% of the campuses. Sapling (trees with 2.5-12.5 cm stem diameter at 1.4 m above ground level) populations were similar to tree populations. The mean and median campus sapling population was 23 and 13, respectively. Flowering dogwood (Cornus florida L.) and red maple were the most abundant sapling species, each accounting for about 10% of all inventoried saplings. Flowering dogwood, red maple, Bradford pear (Pyrus calleryana Decne. ‘Bradford’), willow oak (Quercus phellos L. ), and ornamental cherry (Prunus spp. ) were the most frequently inventoried sapling species, each present on more than 25% of the campuses. Across all campuses, species diversity was relatively low: less than 10 species accounted for over 50% of the inventoried trees and saplings. Prominent Virginia natives, in particular Carya and Quercus species, were under represented in the inventory

    A "thoughtful" Local Friendliness no-go theorem: a prospective experiment with new assumptions to suit

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    A recent paper by two of us and co-workers, based on an extended Wigner's friend scenario, demonstrated that certain empirical correlations predicted by quantum theory (QT) violate inequalities derived from a set of metaphysical assumptions we called "Local Friendliness" (LF). These assumptions are strictly weaker than those used for deriving Bell inequalities. Crucial to the theorem was the premise that a quantum system with reversible evolution could be an observer (colloquially, a "friend"). However, that paper was noncommittal on what would constitute an observer for the purpose of an experiment. Here, we present a new LF no-go theorem which takes seriously the idea that a system's having thoughts is a sufficient condition for it to be an observer. Our new derivation of the LF inequalities uses four metaphysical assumptions, three of which are thought-related, including one that is explicitly called "Friendliness". These four assumptions, in conjunction, imply LF for the type of friend that Friendliness commits one to accepting as an observer. In addition to these four metaphysical assumptions, this new no-go theorem requires two assumptions about what is technologically feasible: Human-Level Artificial Intelligence, and Universal Quantum Computing which is fast and large scale. The latter is often motivated by the belief that QT is universal, but this is not an assumption of the theorem. The intent of the new theorem is to give a clear goal for future experimentalists, and a clear motivation for trying to achieve that goal, by using carefully chosen and widely held assumptions. The popular stance that "quantum theory needs no interpretation" does not question any of our assumptions and so is ruled out by the theorem. Finally, we quantitatively discuss how difficult the experiment we envisage would be, and briefly discuss milestones on the paths towards it.Comment: 36 pages, 1 figur

    First-year Experience Course: Problem Solving, Inquiry, and Integration

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    In an effort to address academic deficiencies outlined in recent studies, Virginia Tech’s College of Natural Resources and Environment redesigned its first-year experience class to fit their activities into three components of activities: problem solving, inquiry, and integrative learning. The problem solving component required students to define a problem, identify problem-solving strategies, and propose solutions and hypotheses. The inquiry component of the first-year experience included selecting a research topic, learning how to access information about the topic, learning how to evaluate existing information about the topic, and deciding which information to use to achieve desired results about the topic. The final component of the program, integration of learning, connected different programs of study with in-class learning and outside experience. This component also stressed exploring the relationship between student’s self and their learning experiences. To evaluate these three categories, the Motivated Strategies for Learning Questionnaire and the Information Literacy Test surveys were administered to the students at the beginning of the semester and the end of the semester in order to evaluate student growth in each category, as well as students’ own self-awareness. Quantitative analysis of these two surveys illustrates the effectiveness of the assignments associated with each component. Knowledge gained from the redevelopment of the class, quantitative analysis of the surveys, and plans for additional amendments to the class will be shared during conference proceedings

    Use of Urban Tree Canopy Assessments by Localities in the Chesapeake Bay Watershed

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    Urban tree canopy (UTC) in the Chesapeake Bay watershed (CBW) provides numerous environmental, economic, and societal benefits. UTC assessments use remote sensing technology to deliver a comprehensive spatial snapshot of a locality’s existing UTC. Because UTC assessments delineate the extent and location of tree canopy cover in the context of other land covers (including plantable space), they are important for establishing tree canopy goals, creating and implementing strategies to achieve those goals, and monitoring progress. Over the past decade, UTC assessments have been completed for numerous localities in the CBW as a result of the Chesapeake Bay Program identifying UTC as a key strategy for Bay restoration. Our research investigated the prevalence of UTC assessments within the CBW and studied how localities are using them. We conducted two surveys: 1) a pilot survey of Virginia localities that received UTC assessments as part of the Virginia UTC project; and 2) a comprehensive survey of all 101 localities in the CBW with populations over 2,500 for which a UTC assessment existed as of May 2013. Surprisingly, 33% of localities in the CBW reported being unaware that a UTC assessment had been performed for their jurisdiction. In general, counties and cities were more likely to be aware of the assessments than were towns (or their jurisdictional equivalent). Most localities that were aware of their assessment were using it in some manner for urban forest planning and management; however, the most frequent activities were also the most basic uses, including: educating officials or citizens about the importance of tree canopy (57%), providing a baseline for evaluating progress toward UTC goals (49%), creating a locality-wide tree canopy goal (47%), planning and prioritizing tree plantings (45%), and informing larger initiatives (43%). All other uses of the assessments (i.e., specialized uses) were reported by 33% or fewer of the CBW localities. Our findings point to the need for outreach to local governments about UTC assessments and their potential uses, particularly in light of increasing emphasis in the CBW on managing urban forests and optimizing UTC as a Bay restoration strategy

    Sustainability Beliefs of First-year Students in Natural Resources

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    A crux of the environmental problem is change resistance and few college students possess the critical analysis and persuasive communication skills needed to engage in this dialogue. Furthermore, there is little appreciation among college students for the diversity of beliefs regarding sustainability issues. We surveyed students enrolled in a First-Year Experience class in Virginia Tech’s College of Natural Resources and Environment. We used the Dunlap and Van Liere New Environmental Paradigm (NEP) measurement scale to assess the individual student orientations toward nature and the environment. The students enrolled in this class had enrolled voluntarily based on their interest in the study of the environment or natural resources. Therefore, it was no surprise that the score reflected a belief orientation towards sustainability. Survey results allowed these first-year students to discover the range of opinion among members of a relatively homogeneous sample. The survey provided insights regarding the human-centered or eco-centered orientation of their student peers. We used these findings to encourage revision of a draft problem-solving essay. We plan further use of the NEP measurement scale in our curriculum and encourage its adoptions by instructors involved in pedagogy of sustainable thinking
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