Search results for "Frequency drift"

showing 2 items of 2 documents

Black Hole Shadow Drift and Photon Ring Frequency Drift

2021

The apparent angular size of the shadow of a black hole in an expanding Universe is redshift-dependent. Since cosmological redshifts change with time - known as the redshift drift - all redshift-dependent quantities acquire a time-dependence, and a fortiori so do black hole shadows. We find a mathematical description of the black hole shadow drift and show that the amplitude of this effect is of order $10^{-16}$ per day for M87$^{\star}$. While this effect is small, we argue that its non-detection can be used to constrain the accretion rate around supermassive black holes, as well as a novel probe of the equivalence principle. If general relativity is assumed, we infer from the data obtaine…

Cosmology and Nongalactic Astrophysics (astro-ph.CO)General relativityAstrophysics::High Energy Astrophysical PhenomenasuhteellisuusteoriaFrequency driftFOS: Physical sciencesmustat aukotGeneral Relativity and Quantum Cosmology (gr-qc)Astrophysics::Cosmology and Extragalactic AstrophysicsAstrophysicskosmologiaGeneral Relativity and Quantum CosmologyGeneral Relativity and Quantum CosmologyavaruustutkimusfysiikkaEvent Horizon TelescopePhysicsSupermassive black holemaailmankaikkeusOrder (ring theory)Coupling (probability)varjotRedshiftBlack holeavaruusvaloAstrophysics - Cosmology and Nongalactic AstrophysicsThe Open Journal of Astrophysics
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Radial Basis Function Interpolation for Referenceless Thermometry Enhancement

2015

MRgFUS (Magnetic Resonance guided Focused UltraSound) is a new and non-invasive technique to treat different diseases in the oncology field, that uses Focused Ultrasound (FUS) to induce necrosis in the lesion. Temperature change measurements during ultrasound thermo-therapies can be performed through magnetic resonance monitoring by using Proton Resonance Frequency (PRF) thermometry. It measures the phase variation resulting from the temperature-dependent changes in resonance frequency by subtracting one phase baseline image from actual phase. Referenceless thermometry aims to re-duce artefacts caused by tissue motion and frequency drift, fitting the back-ground phase outside the heated reg…

Settore ING-INF/05 - Sistemi Di Elaborazione Delle InformazioniProton resonance frequencyMaterials sciencemedicine.diagnostic_testbusiness.industryFrequency driftUltrasoundPhase (waves)Magnetic resonance imagingRadial Basis Function Interpolation Referenceless Thermometry Artificial Neural Network MRgFUS.Radial basis function interpolationmedicineRadial basis functionbusinessBiomedical engineeringInterpolation
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