2,112 research outputs found

    Weakening boom?

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    Federal Reserve District, 12th ; Economic conditions - West (U.S.)

    Boom in the West

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    Federal Reserve District, 12th ; Economic conditions - West (U.S.)

    Synthetic biology: advancing biological frontiers by building synthetic systems

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    Advances in synthetic biology are contributing to diverse research areas, from basic biology to biomanufacturing and disease therapy. We discuss the theoretical foundation, applications, and potential of this emerging field

    A note on uniform power connectivity in the SINR model

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    In this paper we study the connectivity problem for wireless networks under the Signal to Interference plus Noise Ratio (SINR) model. Given a set of radio transmitters distributed in some area, we seek to build a directed strongly connected communication graph, and compute an edge coloring of this graph such that the transmitter-receiver pairs in each color class can communicate simultaneously. Depending on the interference model, more or less colors, corresponding to the number of frequencies or time slots, are necessary. We consider the SINR model that compares the received power of a signal at a receiver to the sum of the strength of other signals plus ambient noise . The strength of a signal is assumed to fade polynomially with the distance from the sender, depending on the so-called path-loss exponent α\alpha. We show that, when all transmitters use the same power, the number of colors needed is constant in one-dimensional grids if α>1\alpha>1 as well as in two-dimensional grids if α>2\alpha>2. For smaller path-loss exponents and two-dimensional grids we prove upper and lower bounds in the order of O(logn)\mathcal{O}(\log n) and Ω(logn/loglogn)\Omega(\log n/\log\log n) for α=2\alpha=2 and Θ(n2/α1)\Theta(n^{2/\alpha-1}) for α<2\alpha<2 respectively. If nodes are distributed uniformly at random on the interval [0,1][0,1], a \emph{regular} coloring of O(logn)\mathcal{O}(\log n) colors guarantees connectivity, while Ω(loglogn)\Omega(\log \log n) colors are required for any coloring.Comment: 13 page

    Effect of Local District Expenditure in Education per Pupil on SAT Scores

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    Although it seems logical to assume a positive correlation between school funding and student achievement, past studies suggested mixed results. The purpose of this study is to reexamine this association between expenditure and performance. To that end, we investigated various assessment measures and found one that best served as a proxy for student achievement – average district SAT scores, converted from ACT. Data from several states were collected and analyzed initially, but we narrowed down to the State of Illinois – the location with most complete data for our research purpose and least data irregularities. Illinois is the chosen population, each school district represents a statistic, and there are three districts defined – rural, suburban, and populous. Our research concluded with a similar observation by the previous literature: more money invested in education does not necessarily translate to higher test scores. However, our finding suggests that when population is taken into account, the more populous the district is, the greater and positive correlation may be present between spending and performance

    Adaptive Choice-Based Conjoint Analysis

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    Conjoint analysis (CA) has emerged as an important approach to the assessment of health service preferences. This article examines Adaptive Choice-Based Conjoint Analysis (ACBC) and reviews available evidence comparing ACBC with conventional approaches to CA. ACBC surveys more closely approximate the decision-making processes that influence real-world choices. Informants begin ACBC surveys by completing a build-your-own (BYO) task identifying the level of each attribute that they prefer. The ACBC software composes a series of attribute combinations clustering around each participant’s BYO choices. During the Screener section, informants decide whether each of these concepts is a possibility or not. Probe questions determine whether attribute levels consistently included in or excluded from each informant’s Screener section choices reflect ‘Unacceptable’ or ‘Must Have’ simplifying heuristics. Finally, concepts identified as possibilities during the Screener section are carried forward to a Choice Tournament. The winning concept in each Choice Tournament set advances to the next choice set until a winner is determined. A review of randomized trials and cross-over studies suggests that, although ACBC surveys require more time than conventional approaches to CA, informants find ACBC surveys more engaging. In most studies, ACBC surveys yield lower standard errors, improved prediction of hold-out task choices, and better estimates of real-world product decisions than conventional choice-based CA surveys
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