Erlend S. Riis

ORCID: 0000-0001-9656-4123
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About
Contact & Profiles
Research Areas
  • Sparse and Compressive Sensing Techniques
  • Advanced Optimization Algorithms Research
  • Merger and Competition Analysis
  • Numerical methods in inverse problems
  • Advanced Numerical Methods in Computational Mathematics
  • Stochastic Gradient Optimization Techniques
  • Advanced Numerical Analysis Techniques
  • Gaussian Processes and Bayesian Inference
  • Neurogenesis and neuroplasticity mechanisms
  • Digital Platforms and Economics
  • Single-cell and spatial transcriptomics
  • Pluripotent Stem Cells Research
  • Global trade and economics
  • Model Reduction and Neural Networks
  • Economic Growth and Productivity

University of Cambridge
2017-2024

Norwegian University of Science and Technology
2024

University of Bath
2024

Ufuk University
2023

The human brain has undergone rapid expansion since humans diverged from other great apes, but the mechanism of this human-specific enlargement is still unknown. Here, we use cerebral organoids derived human, gorilla, and chimpanzee cells to study developmental mechanisms driving evolutionary expansion. We find that neuroepithelial differentiation a protracted process in involving previously unrecognized transition state characterized by change cell shape. Furthermore, show are larger due...

10.1016/j.cell.2021.02.050 article EN cc-by Cell 2021-03-24

Abstract The human brain has undergone rapid expansion since humans diverged from other great apes, but the mechanism of this human-specific enlargement is still unknown. Here, we use cerebral organoids derived human, gorilla and chimpanzee cells to study developmental mechanisms driving evolutionary expansion. We find that differentiation neuroepithelial neurogenic radial glia a protracted process in involving previously unrecognized transition state characterized by change cell shape....

10.1101/2020.07.04.188078 preprint EN bioRxiv (Cold Spring Harbor Laboratory) 2020-07-04

Discrete gradient methods are geometric integration techniques that can preserve the dissipative structure of flows. Due to monotonic decay function values, they well suited for general convex and nonconvex optimization problems. Both zero- first-order algorithms be derived from discrete method by selecting different gradients. In this paper, we present a comprehensive analysis optimisation which provides solid theoretical foundation. We show is well-posed proving existence uniqueness...

10.48550/arxiv.1805.06444 preprint EN other-oa arXiv (Cornell University) 2018-01-01

Discrete gradient methods are geometric integration techniques that can preserve the dissipative structure of flows. Due to monotonic decay function values, they well suited for general convex and nonconvex optimisation problems. Both zero- first-order algorithms be derived from discrete method by selecting different gradients. In this paper, we present a thorough analysis which provides solid theoretical foundation. We show is well-posed proving existence iterates any positive time step, as...

10.1093/imanum/drae037 article EN cc-by IMA Journal of Numerical Analysis 2024-07-01

10.1016/j.ijindorg.2018.10.001 article EN International Journal of Industrial Organization 2018-10-13

Abstract The optimisation of nonsmooth, nonconvex functions without access to gradients is a particularly challenging problem that frequently encountered, for example in model parameter problems. Bilevel parameters standard setting areas such as variational regularisation problems and supervised machine learning. We present efficient robust derivative-free methods called randomised Itoh–Abe methods. These are generalisations the discrete gradient method, well-known scheme from geometric...

10.1007/s10208-020-09489-2 article EN cc-by Foundations of Computational Mathematics 2021-07-29

Stepwise models of technological progress described by Philippe Aghion and his co-authors (1997, 2001, 2005) capture the incentives firms to innovate in order escape competition disincentives from sharing profits with other leaders. The yield intuitively appealing predictions about effects on innovation, but they are limited duopolies. This paper extends oligopolies shows that innovation duopoly do not generalize oligopolies.

10.2139/ssrn.2964062 article EN SSRN Electronic Journal 2017-01-01

In this paper we propose optimisation methods for variational regularisation problems based on discretising the inverse scale space flow with discrete gradient methods. Inverse generalises flows by incorporating a generalised Bregman distance as underlying metric. Its discrete-time counterparts, iterations and linearised iterations, are popular schemes that incorporate priori information without loss of contrast. Discrete tools from geometric numerical integration preserving energy...

10.1007/s10851-020-00944-x article EN cc-by Journal of Mathematical Imaging and Vision 2020-02-03

The optimisation of nonsmooth, nonconvex functions without access to gradients is a particularly challenging problem that frequently encountered, for example in model parameter problems. Bilevel parameters standard setting areas such as variational regularisation problems and supervised machine learning. We present efficient robust derivative-free methods called randomised Itoh--Abe methods. These are generalisations the discrete gradient method, well-known scheme from geometric integration,...

10.48550/arxiv.1807.07554 preprint EN other-oa arXiv (Cornell University) 2018-01-01

The effects of monopoly power or mergers on incentives to innovate are important issues for antitrust enforcement, but they receive relatively little attention in litigated cases compared the analysis predicted prices. This paper reviews what is known about relationship between market structure and innovation its implications enforcement. A focus significance inverted-U result dynamic markets identified research by Philippe Aghion, Peter Howitt, their co-authors. We note that these results...

10.2139/ssrn.4034800 article EN SSRN Electronic Journal 2022-01-01
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