4,199 research outputs found
An institutional perspective on retail internationalization success: Home Depot in Chile
This study utilizes institutional theory to assess the effect of the host institutional environment on the success of internationalizing retailers. According to this framework, retailers succeed in international markets when they adapt their retail format and practices to the salient institutional norms in the host market and achieve legitimation from the relevant social actors. This framework was used in a case study of Home Depot’s entry into Chile in 1998 and its exit three years later. Findings showed that Home Depot lacked legitimacy in Chile because they failed to offer the range of merchandise and store atmosphere demanded by the traditional family shopping activity, and because their management team did not embed themselves in the broader social network. It was also apparent the competition had anticipated and responded to Home Depot’s source of competitive advantage and that Home Depot’s scale was not great enough to command any advantages in the supply chain network
Constructing Light Spanners Deterministically in Near-Linear Time
Graph spanners are well-studied and widely used both in theory and practice. In a recent breakthrough, Chechik and Wulff-Nilsen [Shiri Chechik and Christian Wulff-Nilsen, 2018] improved the state-of-the-art for light spanners by constructing a (2k-1)(1+epsilon)-spanner with O(n^(1+1/k)) edges and O_epsilon(n^(1/k)) lightness. Soon after, Filtser and Solomon [Arnold Filtser and Shay Solomon, 2016] showed that the classic greedy spanner construction achieves the same bounds. The major drawback of the greedy spanner is its running time of O(mn^(1+1/k)) (which is faster than [Shiri Chechik and Christian Wulff-Nilsen, 2018]). This makes the construction impractical even for graphs of moderate size. Much faster spanner constructions do exist but they only achieve lightness Omega_epsilon(kn^(1/k)), even when randomization is used.
The contribution of this paper is deterministic spanner constructions that are fast, and achieve similar bounds as the state-of-the-art slower constructions. Our first result is an O_epsilon(n^(2+1/k+epsilon\u27)) time spanner construction which achieves the state-of-the-art bounds. Our second result is an O_epsilon(m + n log n) time construction of a spanner with (2k-1)(1+epsilon) stretch, O(log k * n^(1+1/k) edges and O_epsilon(log k * n^(1/k)) lightness. This is an exponential improvement in the dependence on k compared to the previous result with such running time. Finally, for the important special case where k=log n, for every constant epsilon>0, we provide an O(m+n^(1+epsilon)) time construction that produces an O(log n)-spanner with O(n) edges and O(1) lightness which is asymptotically optimal. This is the first known sub-quadratic construction of such a spanner for any k = omega(1).
To achieve our constructions, we show a novel deterministic incremental approximate distance oracle. Our new oracle is crucial in our construction, as known randomized dynamic oracles require the assumption of a non-adaptive adversary. This is a strong assumption, which has seen recent attention in prolific venues. Our new oracle allows the order of the edge insertions to not be fixed in advance, which is critical as our spanner algorithm chooses which edges to insert based on the answers to distance queries. We believe our new oracle is of independent interest
Review of First International Conference on Computer Music, Massachusetts Institute of Technology
 
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Session B7 - York Haven Shad Migration: Which Way Did They Go?
The York Haven Hydroelectric Project is fourth in a series of hydroelectric dams on the lower Susquehanna River with upstream passage facilities for American shad and other species. As part of relicensing studies at York Haven, resource agencies have requested that a radio telemetry tracking study of American shad be performed to estimate upstream passage efficiency at the existing Project fish ladder and to evaluate migratory patterns within the larger Project area. In response to this request, a two tiered radio telemetry study of both long distance migration efficiency and near field movements and behavior was conducted in the spring of 2010. American shad were captured at the downstream dam fishway and 180 radio tagged fish were tracked over 26 miles of the Susquehanna River via a network of 17 monitoring stations with 21 antenna zones. Tier 1 study results showed that 70 percent (127 shad) migrated the 26 miles of river between dams, and 4 percent of those arriving at York Haven (5 shad) successfully passed upstream through the fishway. Tier 2 detailed analyses of shad movements and migratory behavior within the large and complex study area at the base of the York Haven dams was also undertaken. This analysis revealed a diverse array of shad migratory behaviors, and also some very consistent patterns. Overall, every fish arriving at the project visited the powerhouse tailrace at least once and generally spent the majority of time there. Beyond this common behavior however, many of the shad moved beyond the powerhouse tailrace, and displayed a wide array of searching migratory patterns in the study area. These study results have now led to an evaluation of possible fish passage enhancement scenarios at York Haven
Angular EPR paradox
The violation of local uncertainty relations is a valuable tool for detecting
entanglement, especially in multi-dimensional systems. The orbital angular
momentum of light provides such a multi-dimensional system. We study quantum
correlations for the conjugate variables of orbital angular momentum and
angular position. We determine an experimentally testable criterion for the
demonstration of an angular version of the EPR paradox. For the interpretation
of future experimental results from our proposed setup, we include a model for
the indeterminacies inherent to the angular position measurement. For this
measurement angular apertures are used to determine the probability density of
the angle. We show that for a class of aperture functions a demonstration of an
angular EPR paradox, according to our criterion, is to be expected.Comment: 21 pages, 9 figures, to be published in J. Mod. Opt. special issue on
quantum imagin
The Exile\u27s War
In Gaelwyn, the village of a thousand stories, Katchan receives a powerful ruby and an ancient technique called writing hidden by his grandmother, Maggaline. Jealous of the power Katchan has, the village Elder seeks to destroy him. After escaping the Elder, Katchan must leave his home and traverse a dangerous and mysterious wasteland that will lead him directly into an ancient conflict that lost a powerful empire to the sands of time
Swellable polymer substrates for use in magnetochemical and optical chemical sensing
Lightly cross-linked, animated polymers that swell and shrink with changing pH were prepared and evaluated. At low pHs amine sites protonate causing charge to accumulate along the polymer backbone. The polymer then swells to maximize the charge separation. The swelling of the polymer causes a change in a magnetic or optical property that can be measured and related to pH.
Animated hydrogel membranes were prepared by copolymerizing dimethyl amino ethyl methacrylate(DMAEMA) with various comonomer hydrogels. Experiments were conducted to examine the effect of formulation on the ability of the hydrogel membrane to swell. Factors examined included cross-linker type, cross-linker concentration, DMAEMA concentration and comonomer hydrophilicity.
Polymer microspheres were prepared using dispersion polymerization and seeded emulsion polymerization techniques. Poly-(vinyl benzyl chloride-co-2,4,5-trichloro phenyl acrylate)(VBC/TCPA) microspheres were prepared by dispersion polymerization. A factorial design experiment was carried out to examine the effect of monomer concentration, stabilizer concentration and water concentration on the size of VBC/TCPA particles stabilized with poly-acrylic acid. Microspheres were prepared using poly(vinylpyrrolidone) as the steric stabilizer. These particles were 0.6 mum in diameter and were used in optical sensing experiments. Seeded emulsion polymerization was used to produce porous particles of poly(VBC) with diameters of 1.3 mum.
The pH sensitive hydrogel membranes were incorporated into two types of magnetochemical sensors; the magnetostatic coupled sensor and the magnetoelastic sensor. Both sensor designs responded to solution pH due to swelling or shrinking of the hydrogel. In addition, the magnetoelastic strip was evaluated for measuring viscosity and for monitoring polymerization processes.
VBC/TCPA microspheres were used in several optical sensing methods. Poly(vinyl alcohol) membranes with VBC/TCPA microspheres were used to examine the feasibility of monitoring solution pH by surface plasmon resonance. A number of hydrogels of varying hydrophilicities with VBC/TCPA microspheres were examined by UV/Vis spectrophotometry, to examine the effect of membrane hydrophilicity on response for potential use in a remote fiber optic chemical sensor. The reproducibility of poly(VBC) microspheres in a HEMA membrane was examined. No change in response was observed after 100 swelling and shrinking cycles. Exposure to 80°C temperature or light for 40 days had only a small change on the magnitude of response
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