1,977 research outputs found

    The Technology Bias in Entrepreneur-Investor Negotiations

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    Entrepreneur-investor negotiations are pivotal for ventures in need of funding. Yet, to date, little is known about the dynamics of these negotiations. We investigate a critical feature of this phenomenon by examining the role of technology, via cognitive heuristics, in shaping entrepreneur and investor perceptions as well as subsequent negotiation outcomes. In a controlled laboratory setting, we simulated 103 negotiations between entrepreneurs and investors. We hypothesize and find that there is a pervasive technology bias that influences the perceptions of both parties of the negotiation, and consequently negotiation outcomes. Our findings offer unique insights into the relationships of technology, cognitive heuristics, and negotiations. We discuss the implications for both practitioners and theoreticians in the areas of technology, decision making, negotiations, and entrepreneurial financing

    Converting Land from Poplar Tree Bioenergy Planting to Cropland: An Example

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    Many landowners ask about the process and costs for returning land to crop production after trees are cut for biomass. A field on the Squaw Creek bottom, Story County, Iowa was planted to hybrid poplar trees in spring 2000. The trees were planted in rows with a 10-ft spacing. The trees were cut in spring 2010. The resulting field was four acres, and this is the account of the first corn crop in 2011 on the area

    Lessons from the Congested Clique Applied to MapReduce

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    The main results of this paper are (I) a simulation algorithm which, under quite general constraints, transforms algorithms running on the Congested Clique into algorithms running in the MapReduce model, and (II) a distributed O(Δ)O(\Delta)-coloring algorithm running on the Congested Clique which has an expected running time of (i) O(1)O(1) rounds, if Δ≄Θ(log⁥4n)\Delta \geq \Theta(\log^4 n); and (ii) O(log⁥log⁥n)O(\log \log n) rounds otherwise. Applying the simulation theorem to the Congested-Clique O(Δ)O(\Delta)-coloring algorithm yields an O(1)O(1)-round O(Δ)O(\Delta)-coloring algorithm in the MapReduce model. Our simulation algorithm illustrates a natural correspondence between per-node bandwidth in the Congested Clique model and memory per machine in the MapReduce model. In the Congested Clique (and more generally, any network in the CONGEST\mathcal{CONGEST} model), the major impediment to constructing fast algorithms is the O(log⁥n)O(\log n) restriction on message sizes. Similarly, in the MapReduce model, the combined restrictions on memory per machine and total system memory have a dominant effect on algorithm design. In showing a fairly general simulation algorithm, we highlight the similarities and differences between these models.Comment: 15 page

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    Minimally-invasive debulking of ovarian cancer in the rat pelvis by means of photodynamic therapy using the pegylated photosensitizer PEG-m-THPC

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    Interstitial photodynamic therapy (PDT) using the pegylated photosensitizer PEG-m-THPC was evaluated as a minimally-invasive procedure to selectively debulk unrespectable pelvic ovarian cancer (NuTu-19) in immunocompetent rats. To assess tumour selectivity, PEG-m-THPC at dosages of 0.3, 3.0 and 30 mg kg−1 body weight was administered intravenously to 30 rats 4 weeks following tumour induction. Eight days later laser light at 652 nm and optical doses ranging from 100 to 900 J cm−1 diffuser-length was delivered by an interstitial cylindrical diffusing fibre inserted blindly into the pelvis. Three days following light application, the volume of necrosis was measured and the damage to pelvic organs was assessed histologically on cross sections. For analysis of survival, 20 tumour-bearing rats received PDT using drug doses of 3 or 9 mg kg−1 body weight and an optical dose of 900 J cm−1 diffuser-length, whereas ten untreated tumour-bearing rats served as controls. The histological assessment of PDT induced necrosis showed a non-linear dose–response for both the photosensitizer dose and the optical dose. The lowest drug dose activated with the highest optical dose did not induce more necrosis than seen in tumour-bearing control animals. The same optical dose induced necrosis of 17 mm in diameter using 30 mg kg−1 and 11 mm using 3 mg kg−1 photosensitizer. The optical threshold for induction of significant necrosis was between 100 and 300 J cm−1 diffuser-length for 30 mg kg−1 and between 300 and 500 J cm−1 for 3 mg kg−1 PEG-m-THPC. Significant damage to normal pelvic organs was only seen if 30 mg kg−1 photosensitizer was activated with optical doses of 700 J cm−1 or more. In the survival study, all treated animals survived PDT for at least 2 weeks and the intestinal and urinary tract remained functional. No clinical signs of blood vessel or nerve injury were observed. Mean overall survival of untreated tumour-bearing rats was 25.0 ± 4.5 days compared to 38.4 ± 3.8 days and 40.0 ± 3.6 days for rats treated with 3 mg kg−1 or 9 mg kg−1 PEG-m-THPC mediated PDT respectively (P < 0.05). We conclude that PEG-m-THPC mediated PDT has a favourable therapeutic window and that this minimally-invasive procedure can reduce pelvic cancer bulks effectively and selectively. © 1999 Cancer Research Campaig

    Optical tweezers escape forces

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    With suitable calibration, optical tweezers can be used to measure forces. If the maximum force that can be exerted is of interest, calibration can be performed using viscous drag to remove a particle from the trap, typically by moving the stage. The stage velocity required to remove the particle then gives the escape force. However, the escape force can vary by up to 30% or more, depending on the particle trajectory. This can have significant quantitative impact on measurements. We describe the variation of escape force and escape trajectory, using both experimental measurements and simulations, and discuss implications for experimental measurement of forces

    On Convergence of the Inexact Rayleigh Quotient Iteration with the Lanczos Method Used for Solving Linear Systems

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    For the Hermitian inexact Rayleigh quotient iteration (RQI), the author has established new local general convergence results, independent of iterative solvers for inner linear systems. The theory shows that the method locally converges quadratically under a new condition, called the uniform positiveness condition. In this paper we first consider the local convergence of the inexact RQI with the unpreconditioned Lanczos method for the linear systems. Some attractive properties are derived for the residuals, whose norms are Οk+1\xi_{k+1}'s, of the linear systems obtained by the Lanczos method. Based on them and the new general convergence results, we make a refined analysis and establish new local convergence results. It is proved that the inexact RQI with Lanczos converges quadratically provided that Οk+1≀Ο\xi_{k+1}\leq\xi with a constant Ο≄1\xi\geq 1. The method is guaranteed to converge linearly provided that Οk+1\xi_{k+1} is bounded by a small multiple of the reciprocal of the residual norm ∄rk∄\|r_k\| of the current approximate eigenpair. The results are fundamentally different from the existing convergence results that always require Οk+1<1\xi_{k+1}<1, and they have a strong impact on effective implementations of the method. We extend the new theory to the inexact RQI with a tuned preconditioned Lanczos for the linear systems. Based on the new theory, we can design practical criteria to control Οk+1\xi_{k+1} to achieve quadratic convergence and implement the method more effectively than ever before. Numerical experiments confirm our theory.Comment: 20 pages, 8 figures. arXiv admin note: text overlap with arXiv:0906.223
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