11,456 research outputs found
Ethanol production and maximum cell growth are highly correlated with membrane lipid composition during fermentation as determined by lipidomic analysis of 22 saccharomyces cerevisiae strains
No full textOptimizing ethanol yield during fermentation is important for efficient production of fuel alcohol, as well as wine and other alcoholic beverages. However, increasing ethanol concentrations during fermentation can create problems that result in arrested or sluggish sugar-to-ethanol conversion. The fundamental cellular basis for these problem fermentations, however, is not well understood. Small-scale fermentations were performed in a synthetic grape must using 22 industrial Saccharomyces cerevisiae strains (primarily wine strains) with various degrees of ethanol tolerance to assess the correlation between lipid composition and fermentation kinetic parameters. Lipids were extracted at several fermentation time points representing different growth phases of the yeast to quantitatively analyze phospholipids and ergosterol utilizing atmospheric pressure ionization-mass spectrometry methods. Lipid profiling of individual fermentations indicated that yeast lipid class profiles do not shift dramatically in composition over the course of fermentation. Multivariate statistical analysis of the data was performed using partial least-squares linear regression modeling to correlate lipid composition data with fermentation kinetic data. The results indicate a strong correlation (R² = 0.91) between the overall lipid composition and the final ethanol concentration (wt/wt), an indicator of strain ethanol tolerance. One potential component of ethanol tolerance, the maximum yeast cell concentration, was also found to be a strong function of lipid composition (R² = 0.97). Specifically, strains unable to complete fermentation were associated with high phosphatidylinositol levels early in fermentation. Yeast strains that achieved the highest cell densities and ethanol concentrations were positively correlated with phosphatidylcholine species similar to those known to decrease the perturbing effects of ethanol in model membrane systems.Clark M. Henderson, Michelle Lozada-Contreras, Vladimir Jiranek, Marjorie L. Longo, David E. Bloc
A survey of blockholders and corporate control
No full textThe author surveys the empirical literature on large-percentage shareholders in public corporations, focusing on four key issues: the prevalence of blockholders; the motivation for block ownership; the effect of blockholders on executive compensation, leverage, the incidence of takeovers, and a wide range of corporate decisions; and the effect of blockholders on firm value. A central finding of this study is that there is little reason for policymakers or small investors to fear large-percentage shareholders in general, especially when the blockholders are active in firm management.Stockholders ; Corporate governance
XLBlocks: a Block-based Formula Editor for Spreadsheet Formulas
No full textSpreadsheets are frequently used in industry to support critical business decisions. Unfortunately, they also suffer from error-proneness, which sometimes results in costly consequences. Experiments in the field of program education have shown that programmers tend to make fewer errors and can better focus on the logic of a program if they use a block-based language instead of a textual one. We hypothesize that a block-based formula editor could support spreadsheet users in a similar way. Therefore, we develop XLBlocks and conduct a think-aloud study with 13 experienced spreadsheet users from industry. Participants are asked to create and edit several formulas, using our block-based language. We then ask them to evaluate this editor using the Cognitive Dimensions of Notations framework. We found that for all dimensions the block-based formula editor received a better evaluation than the default text-based formula editor.Accepted author manuscriptSoftware Engineerin
An Approximate Conflict Detection and Resolution Model for Moving-Block Signalling by Enhancing RECIFE-MILP
No full textConflict detection and resolution models are being developed to support railway traffic management in taking optimised rescheduling decisions in case of disturbances. Existing models mostly concern fixed-block signalling systems, in which minimum train separation distances are determined based on a preset number of blocks representing worst-case braking distances. In a moving-block signalling system, minimum train separation is based on absolute braking distances and hence depends on train speed differently from how fixed-block conflict detection and resolution models. In this paper, we propose a conflict detection and resolution model that approximates moving-block operations. The model enhances the state-of-the-art fixed-block rescheduling model RECIFE-MILP. The enhancements include a reconsideration of the discretisation of the infrastructure, the introduction of a speed profile alternative and a redefinition of the blocking times. We verify the model by comparing the solutions of the moving-block version with the fixed-block version for a specific scenario. The results indicate that the moving-block model can propose different rescheduling decisions than the fixed-block model with a better delay recovery.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Plannin
Nested row-column designs for near-factorial experiments with two treatment factors and one control treatment
No full textThe authors also thank Queen Mary, University of London, the University of St Andrews and the Poznan University of Life Sciences for financial support. The second author was also supported by the British-Polish Young Scientists Programme, grant WAR/342/116.This paper presents some methods of designing experiments in a block design with nested rows and columns. The treatments consist of all combinations of levels of two treatment factors, with an additional control treatment.Peer reviewe
The Block in the Field: Intensive Out-of-Classroom Experiences
No full textThe purpose of this paper is to examine the extent to which block field trips constitute authentic generative learning opportunities for students and effective curricular choices for instructors. The field trips featured in this research are situated within the context of work integrated learning (WIL) (e.g., Sachs, Rowe, & Wilson, 2016). The theoretical frame used in this study is the WIL Framework developed by Campbell et al. (2019) whose four domains of practice are the student experience, curriculum design, institutional requirements, and stakeholder engagement. Case study methods are used, supported by the interpretivist approaches used in phenomenography. Four types of field trips provide case studies which are analyzed according to their contexts, strengths, challenges, opportunities, and risks. Results of this research reveal that for field trips within the block model, faculty preparation, disciplinary accessibility to field excursions, administrative expectations, student commitment, and user-friendliness of field trip sites must be considered. 
A Block ILUT Smoother for Multipatch Geometries in Isogeometric Analysis
No full textSince its introduction in [20], Isogeometric Analysis (IgA) has established itself as a viable alternative to the Finite Element Method (FEM). Solving the resulting linear systems of equations efficiently remains, however, challenging when high-order B-spline basis functions of order p> 1 are adopted for approximation. The use of Incomplete LU (ILU) type factorizations, like ILU(k) or ILUT, as a preconditioner within a Krylov method or as a smoother within a multigrid method is very effective, but costly [37]. In this paper, we investigate the use of a block ILUT smoother within a p-multigrid method, where the coarse grid correction is obtained at p= 1, and compare it to a global ILUT smoother in case of multipatch geometries. A spectral analysis indicates that the use of the block ILUT smoother improves the overall convergence rate of the resulting p-multigrid method. Numerical results, obtained for a variety of two dimensional benchmark problems, illustrate the potential of this block ILUT smoother for multipatch geometries.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Numerical Analysi
Additive block diagonal preconditioning for block two-by-two linear systems of skew-Hamiltonian coefficient matrices
No full textFor a class of block two-by-two systems of linear equations with certain skew-Hamiltonian coefficient matrices, we construct additive block diagonal preconditioning matrices and discuss the eigen-properties of the corresponding preconditioned matrices. The additive block diagonal preconditioners can be employed to accelerate the convergence rates of Krylov subspace iteration methods such as MINRES and GMRES. Numerical experiments show that MINRES preconditioned by the exact and the inexact additive block diagonal preconditioners are effective, robust and scalable solvers for the block two-by-two linear systems arising from the Galerkin finite-element discretizations of a class of distributed control problems
Experimental Design
No full textThis site, created by Michelle Lacey of Yale University, gives an explanation, a definition of and an example using experimental design. Topics include: experimentation, control, randomization, randomized design, block randomization and replication. Overall, this site provides a good overview of these topics
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