Scientific law | EPFL Graph Search

Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term law has diverse usage in many cases (approximate, accurate, broad, or narrow) across all fields of natural science (physics, chemistry, astronomy, geoscience, biology). Laws are developed from data and can be further developed through mathematics; in all cases they are directly or indirectly based on empirical evidence. It is generally understood that they implicitly reflect, though they do not explicitly assert, causal relationships fundamental to reality, and are discovered rather than invented. Scientific laws summarize the results of experiments or observations, usually within a certain range of application. In general, the accuracy of a law does not change when a new theory of the relevant phenomenon is worked out, but rather the scope of the law's application, since the mathematics or statement representing the law does

'Peak Oil' As Classical Economic Process

François Meynard

Forecasts about 'peak oil', the limits of oil production, are the subject of controversies. 'Peak oil' forecasts are based on extrapolations of a priori chosen mathematical models fitted to field data. Scientifically that is not very sound. To clarify this point, in this paper 'peak oil' is modelled in a generic reductionist, approach, in which the conflicting dynamic between economic forces and physical laws are well identified. This model finds a natural interpretation just supress in a classical economic analysis frame. The 'peak oil' controversy is thus brought into the field of economic thought as a debate between classical and mainstream economics, in particular between an objective and a faith based appraisal about this historical event. The goal is not to improve forecasts about 'peak oil', which is very likely not a predictable event, but to propose an objective framework for the analysis of its systemic effects on economic production.

Multi-Science Publ Co Ltd2014

Learning from radiation at a very high energy lepton collider

Siyu Chen, Alfredo Glioti, Riccardo Rattazzi, Lorenzo Ricci, Andrea Wulzer

We study the potential of lepton collisions with about 10 TeV center of mass energy to probe Electroweak, Higgs and Top short-distance physics at the 100 TeV scale, pointing out the interplay with the long-distance (100 GeV) phenomenon of Electroweak radiation. On one hand, we find that sufficiently accurate theoretical predictions require the resummed inclusion of radiation effects, which we perform at the double logarithmic order. On the other hand, we notice that short-distance physics does influence the emission of Electroweak radiation. Therefore the investigation of the radiation pattern can enhance the sensitivity to new short-distance physical laws. We illustrate these aspects by studying Effective Field Theory contact interactions in di-fermion and di-boson production, and comparing cross-section measurements that require or that exclude the emission of massive Electroweak bosons. The combination of the two types of measurements is found to enhance the sensitivity to the new interactions. Based on these results, we perform sensitivity projections to Higgs and Top Compositeness and to minimal Z' new physics scenarios at future muon colliders.

SPRINGER2022

Force Transmission in Migrating Cells

Maxime Fred Maurice Fournier

Ability to migrate is a fundamental property of all animal cells. Cell migration underlies such important physiological and pathological processes as embryonic development, immune response, tissue regeneration and cancer metastasis. As cell migration involves forces and motion, it is ultimately a physical phenomenon that should be understood in terms of fundamental physical laws. Cell migration mechanisms are based on the activity of the cytoskeleton, a system of intracellular filaments and motor proteins. During cell migration, forces developed by the cytoskeleton are transmitted, through specific adhesions complexes, to the substrate. Composition and dynamics of the cytoskeleton has been subject of many studies, but it remains poorly understood how the cytoskeleton reactions and its interaction with extra cellular matrix are orchestrated to result in coordinated migration behavior. The main part of this thesis consists of the experiments and analysis of force transmission during cell migration in the experimental system of fish epidermal keratocytes. Our experimental approaches involved microinjection for proteins dynamics quantification, micromanipulation, use of compliant substrate, simultaneous imaging of cytoskeleton and substrate deformation, and the use of cytoskeletal inhibitors. In parallel with the experiments, significant computational work has been performed to program and adapt existing algorithms to analyze experimental data. Thanks to the combination of our experimental and computational approaches, we were able to correlate actin dynamics and traction forces over the whole cell, to map the efficiency of force transmission, and to reveal slipping and gripping mechanisms differentially involved in stress transmission in different parts of the cell. We also investigated contributions of actin assembly and myosin-dependent contractility to force generation and provided evidence that cell translocation could be powered by two different engines. Additionally, we performed micromanipulation experiments to identify the cell polarity cues associated with specific cytoskelatal reactions and regions of the cell. We have also collaborated with the laboratory of one of the leading modellers in the field of cell biophysics to validate a new mathematical model of cell migration and force transmission.

EPFL2011

Force Transmission in Migrating Cells

Maxime Fred Maurice Fournier

EPFL2011