Théories d'une vitesse de lumière variable

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Not fully grasping the concepts of relativity can lead to misunderstandings about the fundamental background of synchrotron emission. Here we deal with some intriguing cases, in which the relevant

speed of light' is not the invariant c but the speed with respect to a moving object. This specifically affects two pillars of synchrotron radiation: the Lorentz length contraction and the Doppler shift. We propose a teaching strategy relying on new versions of simple

thought' experiments. Besides putting synchr

Tunable lasers are essential for optical communication, spectroscopy, and precision sensing, where fast and stable wavelength control is required. Conventional tuning approaches rely on either current or temperature tuning, mechanical actuation, or bulky external modulators, limiting speed, stability, or integration. Here, we introduce an external cavity semiconductor laser incorporating a resonant electro-optic metasurface as the external mirror, enabling ultrafast frequency and amplitude control within a

Many aquatic animals, including larval zebrafish, exhibit intermittent locomotion, moving via discrete swimming bouts followed by passive glides rather than continuous movement. However, fundamental questions remain unresolved: What neural mechanisms drive this behavior, and what functional benefits does this behavior offer? Specifically, is intermittent swimming more energy efficient than continuous swimming, and, if so, by what mechanism? Live-animal experiments pose technical challenges, because observin

Nuclear laser spectroscopy at the 10−12 precision level (Nature 633.8028 (2024): 63–70) determined the fractional change in the nuclear quadrupole moment of 229Th upon excitation, ΔQ0/Q0 = 1.791(2)%. Such high-accuracy nuclear parameters enable stringent tests and refinement of 229Th nuclear models. Using a semi-classical prolate-spheroid model, we quantify the transition frequency’s sensitivity to fine-structure constant variations as K = 5900(2300), with uncertainty dominated by the measured charge-radius

Traffic forecasting has been a fundamental task in transportation research, with many methods and datasets mainly based on highway loop detector data. In recent years, drones are becoming a favorable choice for urban traffic monitoring, due to their flexibility, high data quality and larger spatial coverage. However, the lack of public datasets has made the joint use of drone and loop detector data fairly under-explored. Therefore, we create a novel simulated multi-source dataset SimBarca for urban traffic

Variations of material properties along fracture planes play a crucial role in crack propagation behavior. During detachment of adhesives, local perturbations of the crack front are observed, but the mechanisms occurring at the interface remain elusive. This thesis investigates how shapes of different fracture toughness on fracture planes can impede crack propagation. Five patterns are studied (horizontal, vertical and sinusoidal bands, check and crescent shapes). We assess the behaviors of cracks propagati

Pumps running as turbines are pointed out as a cost-effective solution for energy recovery in pressurised water supply systems. However, these hydraulic machines feature low efﬁciency under variable discharge operation due to the lack of an inlet ﬂow contr ...

We investigate viscoplastic fluids (described using a Herschel–Bulkley model) striking a body of water: a fixed volume of a viscoplastic material (a polymeric gel called Carbopol ultrez 10) initially contained in a box is released on a slope and flows down under gravity. When it enters flume filled with water, it generates an impulse wave. The problem is to determine impulse waves’ features from the viscoplastic fluid properties. First, we use momentum and mass conservation in a control volume for modeling

The most recent experiments of disruption mitigation by massive gas injection in ASDEX Upgrade have concentrated on small-relatively to the past-quantities of noble gas injected, and on the search for the minimum amount of gas necessary for the mitigation ...

Zonal flows (ZF) play a crucial role in regulating ion temperature gradient (ITG) turbulence. In previous global gyrokinetic simulations [1] using the ORB5 code with the adiabatic electron model, it was observed that long-lived ZF structures, leading to a ...

We present optical coherence correlation spectroscopy (OCCS), a novel method to study the motion dynamics of nanoparticles within many observation volumes simultaneously. For this purpose, OCCS combines the key features of dark-field optical coherence microscopy (dfOCM) and fluorescence correlation spectroscopy (FCS). dfOCM is a Fourier domain optical coherence microscopy technique offering micrometer three-dimensional spatial resolution and microseconds temporal sampling. The rapid temporal sampling is ach

We study online scheduling on m uniform machines, where m - 1 of them have a reference speed 1 and the last one a speed s with 0

Our goal is to develop motorway traffic risks identification models using disaggregate traffic data, meteorological data and crash database for a study site at a two-lane-per-direction section on motorway A1 in Urtenen-Schönbühl, Switzerland. We define traffic situations - TSs representing traffic status for a certain time duration and traffic regimes - TRs obtained by clustering TSs. The models are traffic regimes – based and are developed using classification and regression trees to identify rear-end coll

Théories d'une vitesse de lumière variable

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Teaching about the relativistic background of synchrotron radiation: some intriguing aspects with strong didactic implications

Metasurface-controlled high-speed tunable external cavity lasers

Energy efficiency and neural control of continuous versus intermittent swimming in a fishlike robot

Fine-structure constant sensitivity of the Th-229 nuclear clock transition

Multi-Source Urban Traffic Prediction Using Drone and Loop Detector Data

Detachment Dynamics of Heterogeneous Adhesive Pads

Variable speed operation of centrifugal pumps running as turbines. Experimental investigation

Viscoplastic fluid impacting a body of water: predicting wave features from the fluid properties

Disruption mitigation by injection of small quantities of noble gas in ASDEX Upgrade

Turbulence and zonal flow structures in the core and L-mode pedestal of tokamak plasmas

Optical Coherence Correlation Spectroscopy (OCCS)

Competitive ratio of List Scheduling on uniform machines and randomized heuristics

Vers un modèle proactif pour identifier des risques de trafic