752 research outputs found

    Bringing the Entrepreneurial Mindset into Mining Engineering Education

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    There has been an ongoing debate on how to transform engineering education to better prepare students for today`s professional world that is characterized by increasingly complex problems and challenges that engineers are tasked with upon entering the industry. Within the conceive–design–implement–operate (CDIO) framework, entrepreneurship education presents a valuable pedagogical approach to foster the necessary skills of the students through integrated, hands-on, active learning experiences. While numerous publications have addressed possibilities of how experiential, problem-based, project-based and active learning can be integrated into engineering curriculum, there has been hardly any attention on mining engineering with respect to adopting this approach. This paper will address the possibilities of integrating entrepreneurship education into mining engineering programs in particular. This paper will enhance and foster discussion among academics from mining engineering on how to integrate elements of entrepreneurship education on a course, program and departmental level to infuse value creation experiences across the curriculum

    Optical Properties of Deep Ice at the South Pole - Absorption

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    We discuss recent measurements of the wavelength-dependent absorption coefficients in deep South Pole ice. The method uses transit time distributions of pulses from a variable-frequency laser sent between emitters and receivers embedded in the ice. At depths of 800 to 1000 m scattering is dominated by residual air bubbles, whereas absorption occurs both in ice itself and in insoluble impurities. The absorption coefficient increases approximately exponentially with wavelength in the measured interval 410 to 610 nm. At the shortest wavelength our value is about a factor 20 below previous values obtained for laboratory ice and lake ice; with increasing wavelength the discrepancy with previous measurements decreases. At around 415 to 500 nm the experimental uncertainties are small enough for us to resolve an extrinsic contribution to absorption in ice: submicron dust particles contribute by an amount that increases with depth and corresponds well with the expected increase seen near the Last Glacial Maximum in Vostok and Dome C ice cores. The laser pulse method allows remote mapping of gross structure in dust concentration as a function of depth in glacial ice.Comment: 26 pages, LaTex, Accepted for publication in Applied Optics. 9 figures, not included, available on request from [email protected]

    Diversity of habitats and bacterial communities support landscape-scale multifunctionality differently across seasons

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    Abstract In this study, we demonstrate how changes in the diversity of habitat and bacterial communities affect landscape multifunctionality. Habitat diversity may beget species diversity by increasing niche availability and resource complementarity. Species diversity, in turn, generally promotes multifunctionality, i.e. the simultaneous performance of multiple ecosystem functions. However, the relationship between habitat diversity and functioning remains to be explicitly explored. In order to test the relationship between habitat diversity and multifunctionality we constructed experimental landscapes of four different habitats common in shallow-water sediment ecosystems: cyanobacterial mats, Ruppia maritima meadows, silty mud and sandy beach. We manipulated the diversity of these habitats over three consecutive seasons and measured bacterial diversity, benthic microalgal diversity and four functions related to marine nitrogen cycling (gross primary production, nitrogen fixation, denitrification and uptake of dissolved inorganic nitrogen). Our results showed that higher habitat and bacterial diversity, but not benthic microalgal diversity, increased landscape multifunctionality. However, the relative importance of habitat and bacterial diversity varied with season. Habitat diversity was generally the strongest driver, affecting multifunctionality directly in summer and indirectly via bacterial diversity in autumn. In spring, neither of the two aspects of diversity was important. Our study demonstrates the importance of considering temporal differences in both habitat and species diversity for landscape multifunctionality, and the importance of direct and indirect effects in mediating ecosystem functions. Habitat homogenization in concert with loss in biodiversity can thus be a driving force of declining ecosystem functioning and the services they underpin

    Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge II.} Charmonia

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    In the precedent paper of the authors (hep-ph/0510410), the bbˉb\bar b states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative decays of the considered bottomonia. In the present paper, such a study is carried out for the charmonium (ccˉ)(c\bar c) states. We reconstruct the interaction in the ccˉc\bar c-sector on the basis of data for the charmonium levels with JPC=0+J^{PC}=0^{-+}, 11^{--}, 0++0^{++}, 1++1^{++}, 2++2^{++}, 1+1^{+-} and radiative transitions ψ(2S)γχc0(1P)\psi(2S)\to\gamma\chi_{c0}(1P), γχc1(1P)\gamma\chi_{c1}(1P), γχc2(1P)\gamma\chi_{c2}(1P), γηc(1S)\gamma\eta_{c}(1S) and χc0(1P)\chi_{c0}(1P), χc1(1P)\chi_{c1}(1P), χc2(1P)γJ/ψ\chi_{c2}(1P)\to\gamma J/\psi. The ccˉc\bar c levels and their wave functions are calculated for the radial excitations with n6n\le 6. Also, we determine the ccˉc\bar c component of the photon wave function using the e+ee^+e^- annihilation data: e+eJ/ψ(3097)e^+e^- \to J/\psi(3097), ψ(3686)\psi(3686), ψ(3770)\psi(3770), ψ(4040)\psi(4040), ψ(4160) \psi(4160), ψ(4415)\psi(4415) and perform the calculations of the partial widths of the two-photon decays for the n=1n=1 states: ηc0(1S)\eta_{c0}(1S), χc0(1P)\chi_{c0}(1P), χc2(1P)γγ\chi_{c2}(1P)\to\gamma\gamma, and n=2n=2 states: ηc0(2S)γγ\eta_{c0}(2S)\to\gamma\gamma, χc0(2P)\chi_{c0}(2P), χc2(2P)γγ\chi_{c2}(2P)\to \gamma\gamma. We discuss the status of the recently observed ccˉc\bar c states X(3872) and Y(3941): according to our results, the X(3872) can be either χc1(2P)\chi_{c1}(2P) or ηc2(1D)\eta_{c2}(1D), while Y(3941) is χc2(2P)\chi_{c2}(2P).Comment: 24 pages, 9 figure

    Quark--antiquark states and their radiative transitions in terms of the spectral integral equation. {\Huge III.} Light mesons

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    We continue the investigation of mesons in terms of the spectral integral equation initiated before [hep-ph/0510410, hep-ph/0511005] for the bbˉb\bar b and ccˉc\bar c systems: in this paper we consider the light-quark (u,d,su, d,s) mesons with masses M3M\le 3 GeV. The calculations have been performed for the mesons lying on linear trajectories in the (n,M2)(n,M^2)-planes, where nn is the radial quantum number. Our consideration relates to the qqˉq\bar q states with one component in the flavor space, with the quark and antiquark masses equal to each other, such as π(0+)\pi(0^{-+}), ρ(1)\rho(1^{--}), ω(1)\omega(1^{--}), ϕ(1)\phi(1^{--}), a0(0++)a_0(0^{++}), a1(1++)a_1(1^{++}), a2(2++)a_2(2^{++}), b1(1+)b_1(1^{+-}), f2(2++)f_2(2^{++}), π2(2+)\pi_2(2^{-+}), ρ3(3)\rho_3(3^{--}), ω3(3)\omega_3(3^{--}), ϕ3(3)\phi_3(3^{--}), π4(4+)\pi_4(4^{-+}) at n6n\le 6. We obtained the wave functions and mass values of mesons lying on these trajectories. The corresponding trajectories are linear, in agreement with data. We have calculated the two-photon decays πγγ\pi\to \gamma\gamma, a0(980)γγa_0(980)\to \gamma\gamma, a2(1320)γγa_2(1320)\to \gamma\gamma, f2(1285)γγf_2(1285)\to \gamma\gamma, f2(1525)γγf_2(1525)\to \gamma\gamma and radiative transitions ργπ\rho\to\gamma\pi, ωγπ\omega\to\gamma\pi, that agree qualitatively with the experiment. On this basis, we extract the singular part of the interaction amplitude, which corresponds to the so-called "confinement interaction". The description of the data requires the presence of the strong tt-channel singularities for both scalar and vector exchanges.Comment: 48 pages, 24 figure

    Charmed quark component of the photon wave function

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    We determine the c-anti-c component of the photon wave function on the basis of (i) the data on the transitions e+ e- -> J/psi(3096), psi(3686), psi(4040), psi(4415), (ii) partial widths of the two-photon decays eta_{c0}(2979), chi_{c0}(3415), chi_{c2}(3556) -> gamma-gamma, and (iii) wave functions of the charmonium states obtained by solving the Bethe-Salpeter equation for the c-anti-c system. Using the obtained c-anti-c component of the photon wave function we calculate the gamma-gamma decay partial widths for radial excitation 2S state, eta_{c0}(3594) -> gamma-gamma, and 2P states chi_{c0}(3849), chi_{c2}(3950) -> gamma-gamma.Comment: 20 pages, 8 figure

    The AMANDA Neutrino Telescope and the Indirect Search for Dark Matter

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    With an effective telescope area of order 10^4 m^2, a threshold of ~50 GeV and a pointing accuracy of 2.5 degrees, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe its performance, focussing on the capability to detect halo dark matter particles via their annihilation into neutrinos.Comment: Latex2.09, 16 pages, uses epsf.sty to place 15 postscript figures. Talk presented at the 3rd International Symposium on Sources and Detection of Dark Matter in the Universe (DM98), Santa Monica, California, Feb. 199

    Inheritance patterns in citation networks reveal scientific memes

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    Memes are the cultural equivalent of genes that spread across human culture by means of imitation. What makes a meme and what distinguishes it from other forms of information, however, is still poorly understood. Our analysis of memes in the scientific literature reveals that they are governed by a surprisingly simple relationship between frequency of occurrence and the degree to which they propagate along the citation graph. We propose a simple formalization of this pattern and we validate it with data from close to 50 million publication records from the Web of Science, PubMed Central, and the American Physical Society. Evaluations relying on human annotators, citation network randomizations, and comparisons with several alternative approaches confirm that our formula is accurate and effective, without a dependence on linguistic or ontological knowledge and without the application of arbitrary thresholds or filters.Comment: 8 two-column pages, 5 figures; accepted for publication in Physical Review

    The AMANDA Neutrino Telescope: Principle of Operation and First Results

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    AMANDA is a high-energy neutrino telescope presently under construction at the geographical South Pole. In the Antarctic summer 1995/96, an array of 80 optical modules (OMs) arranged on 4 strings (AMANDA-B4) was deployed at depths between 1.5 and 2 km. In this paper we describe the design and performance of the AMANDA-B4 prototype, based on data collected between February and November 1996. Monte Carlo simulations of the detector response to down-going atmospheric muon tracks show that the global behavior of the detector is understood. We describe the data analysis method and present first results on atmospheric muon reconstruction and separation of neutrino candidates. The AMANDA array was upgraded with 216 OMs on 6 new strings in 1996/97 (AMANDA-B10), and 122 additional OMs on 3 strings in 1997/98.Comment: 36 pages, 23 figures, submitted to Astroparticle Physic
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