1,537 research outputs found

    Clarity of Microstamped Identifiers as a Function of Primer Hardness and Type of Firearm Action

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    The transfer of microstamped identifiers to the primers of fired cartridges was examined using a stereomicroscope and scanning electron microscope (SEM). The identifiers were placed on the firing pins of three different 9mm handguns, namely, a Sig Sauer, a Taurus, and a Hi-Point. Ten different brands of ammunition were fired from each handgun, 100 rounds being fired using each brand for a total of 1000 rounds fired per handgun. The quality of the markings was evaluated using a simple observation rubric. These results were compared to Vickers hardness values obtained from the ammunition primers and are discussed in light of the types of actions of firearms used

    5.5-7.5 MeV Proton generation by a moderate intensity ultra-short laser interaction with H2O nano-wire targets

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    We report on the first generation of 5.5-7.5 MeV protons by a moderate intensity short-pulse laser (4.5 \times 1017 W/cm^2, 50 fsec) interacting with H2O nano-wires (snow) deposited on a Sapphire substrate. In this setup, the laser intensity is locally enhanced by the tip of the snow nano-wire, leading to high spatial gradients. Accordingly, the plasma near the tip is subject to enhanced ponderomotive potential, and confined charge separation is obtained. Electrostatic fields of extremely high intensities are produced over the short scale length, and protons are accelerated to MeV-level energies.Comment: submitted to PRL, under press embargo. 6 figure

    Current Challenges And Solution Approaches In Empirical Engineering Design Research – A Workshop For Empirical Research

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    The requirements on validity for studies in design research are very high. Therefore, this paper aims at identifying challenges that occur when setting up studies and suggests solution strategies to address them. Three different institutes combining their experience discussed several studies in a workshop. Resulting main challenges are to find a suitable task, to operationalise the variables and to deal with a high analysis effort per participant. Automation in data evaluation and a detailed practical guideline on studies in design research are considered necessary

    Surrogate-based optimization of tidal turbine arrays: a case study for the Faro-OlhĂŁo inlet

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    This paper presents a study for estimating the size of a tidal turbine array for the Faro-OlhĂŁo Inlet (Potugal) using a surrogate optimization approach. The method compromises problem formulation, hydro-morphodynamic modelling, surrogate construction and validation, and constraint optimization. A total of 26 surrogates were built using linear RBFs as a function of two design variables: number of rows in the array and Tidal Energy Converters (TECs) per row. Surrogates describe array performance and environmental effects associated with hydrodynamic and morphological aspects of the multi inlet lagoon. After validation, surrogate models were used to formulate a constraint optimization model. Results evidence that the largest array size that satisfies performance and environmental constraints is made of 3 rows and 10 TECs per row.Eduardo GonzĂĄlez-Gorbeña has received funding for the OpTiCA project (http://msca-optica.eu/) from the Marie SkƂodowska-Curie Actions of the European Union's H2020-MSCA-IF-EF-RI-2016 / GA#: 748747. The paper is a contribution to the SCORE pro-ject, funded by the Portuguese Foundation for Science and Technology (FCT–PTDC/AAG-TEC/1710/2014). AndrĂ© Pacheco was supported by the Portuguese Foun-dation for Science and Technology under the Portuguese Researchers’ Programme 2014 entitled “Exploring new concepts for extracting energy from tides” (IF/00286/2014/CP1234).info:eu-repo/semantics/publishedVersio

    Fools gold? Developer dilemmas in a closed mobile application market platform

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    In this paper, we outline some potential conflicts that platform owners and software developers face in mobile application markets. Our arguments are based on comments captured in specialized online discussion forums, in which developers gather to share knowledge and experiences. The key findings indicate conflicts of interests, including 1) intra-platform competition, 2) discriminative promotion, 3) entry prevention, 4) restricted monetization, 5) restricted knowledge sharing, 6) substitution, and 7) strategic technology selection. Opportunistic platform owners may use their power to discriminate between third-part software developers. However, there are also potential strategic solutions that developers can apply; for example diversification (multi-homing), syndication and brand building.Comment: Presented at the 15th International Conference on Electronic Commerce, ICEC 2013, Turku, Finland, August 13-15, 201

    Investigating the mix of strategic choices and performance of transaction platforms: Evidence from the crowdfunding setting

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    Research Summary: The platform literature offers keen insights on the pricing and non-pricing strategies that transaction platforms undertake. We supplement this work by studying how platforms mix together their strategic choices and the association with platforms’ performance. To that end, we focus on crowdfunding platforms; a prominent setting of transaction platforms. We present an inductive large-N study of the population of 788 crowdfunding platforms that operated in EU-15 countries up to 2018. Our contribution is threefold: (a) identifying common mixes of strategic choices; (b) tracking deviations from these mixes; and (c) associating these with platforms’ survival and growth. We discuss our findings and how they advance knowledge at the intersection of the platform and strategic management literatures. Managerial Summary: Notable transaction-platforms such as eBay, LinkedIn, and Tencent have an aggregate market-value in the hundreds of billions of dollars. We know that platforms’ success is driven by the strategic choices they undertake. Yet, we know less about how they mix together these choices and the association with platforms’ performance. Our study addresses this gap by focusing on a prominent setting: crowdfunding. Using data on the population of 788 crowdfunding platforms in EU-15 countries, we show that these platforms cluster around three common mixes of strategic choices. Moreover, crowdfunding platforms do not strictly adhere to the strategy mix they are affiliated with. Interestingly, there is a positive association between the degree to which a platform's choices differentiate from its strategy mix and platform's subsequent performance

    Synergistic Effect of Co and Mn Co-Doping on SnO2 Lithium-Ion Anodes

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    The incorporation of transition metals (TMs) such as Co, Fe, and Mn into SnO2 substantially improves the reversibility of the conversion and the alloying reaction when used as a negative electrode active material in lithium-ion batteries. Moreover, it was shown that the specific benefits of different TM dopants can be combined when introducing more than one dopant into the SnO2 lattice. Herein, a careful characterization of Co and Mn co-doped SnO2 via transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction including Rietveld refinement is reported. Based on this in-depth investigation of the crystal structure and the distribution of the two TM dopants within the lattice, an ex situ X-ray photoelectron spectroscopy and ex situ X-ray absorption spectroscopy were performed to better understand the de-/lithiation mechanism and the synergistic impact of the Co and Mn co-doping. The results specifically suggest that the antithetical redox behaviour of the two dopants might play a decisive role for the enhanced reversibility of the de-/lithiation reaction

    Growing with the market : how changing conditions during market growth affect formation and evolution of interfirm ties

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    Research Summary: Market conditions are known to matter for firm performance and growth. This study explores how changing levels of uncertainty and competition affect interfirm ties of entrepreneurial firms as markets transition from nascent to growth stage. Tracing 6 entrepreneurial game publishers during the growth stage of the US wireless gaming market, the findings reveal that in a growth stage market, as uncertainty decreases, certain ties of entrepreneurial firms are terminated. First, existing partners may cut ties and become competitors after entering the market directly. This is a “winner's curse” as more successful firms are more likely to entice their partners to enter the market directly. Second, ties may be terminated as prominent firms that are “overwhelmed” with too many partners cut ties with low to mediocre performance while their remaining partners enter a positive spiral of tie strength and performance. Finally, as uncertainty decreases, new firms may enter the market as competitors to prominent firms. While entrepreneurial firms with high and low performing ties to prominent partners may find ties with these new entrants attractive, those with mediocre ties to few prominent partners find this move too risky and wait for a first mover to legitimate it. Overall, the findings show that changing levels of uncertainty and competition in growth stage markets can have different consequences for firms due to heterogeneity in their ties and power relative to partners. The findings provide several contributions to literature regarding the relationship between interfirm ties, firm performance, and market evolution. Managerial Summary: Based on interviews at 6 entrepreneurial game publishers in the US and their partners, this study shows how changing levels of uncertainty and competition in growing markets can have different consequences for firms based on the different types of alliances in their portfolio and their power relative to partners. The findings highlight the importance of managing partners differently based on alliance type and goal of the partner. They advocate remaining flexible in alliance management as information asymmetries, intentions and bargaining power of partners can change and lead to abrupt alliance dissolution. They show that alliance portfolio management goes beyond a firm's capability of managing individual alliances, and provide a tool for managers to evaluate their alliance portfolios and take the necessary precautions

    Inhibition of the glycaemic response by onion : a comparison between lactose-tolerant and lactose-intolerant adults

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    This document is the Accepted Manuscript of the following article: R Hoffman, G Ranjbar and A M Madden, ‘Inhibition of the glycaemic response by onion: a comparison between lactose-tolerant and lactose-intolerant adults’, European Journal of Clinical Nutritin, (2016), 70: 1089-1091. The Version of Record is available online at doi: 10.1038/ejcn.2016.44.This pilot study compared inhibition of the glycaemic response to glucose by a dietary source of quercetin glucosides (onion) in lactose-tolerant adults (n = 12) and lactose-intolerant adults (n = 12). We hypothesised that lactose-intolerant people (who do not express lactase) will retain intact quercetin glucosides that can inhibit glucose uptake via the glucose transporter SGLT1 whereas lactose-tolerant people (who do express lactase) will hydrolyse quercetin glucosides to free quercetin which does not inhibit glucose uptake. In a glucose tolerance test, reduction of peak glucose levels by an onion meal was higher in lactose-intolerant people than lactose-tolerant people (44.2% versus 19.3%, p = 0.04). Incremental area under the blood glucose curve was reduced more in lactose-intolerant people, but was not statistically significantly (54.5% versus 42.1%, p = 0.42). A diet containing quercetin glucosides may be of greater benefit for glycaemic control in lactose-intolerant people than in lactose-tolerant people.Peer reviewedFinal Accepted Versio
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