Browse
Submit Data
Databases
API
Help

Dataset Information

9 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Effect of Thomas Rotation on the Lorentz Transformation of Electromagnetic fields.

ABSTRACT: A relativistic particle undergoing successive boosts which are non collinear will experience a rotation of its coordinate axes with respect to the boosted frame. This rotation of coordinate axes is caused by a relativistic phenomenon called Thomas Rotation. We assess the importance of Thomas rotation in the calculation of physical quantities like electromagnetic fields in the relativistic regime. We calculate the electromagnetic field tensor for general three dimensional successive boosts in the particle's rest frame as well as the laboratory frame. We then compare the electromagnetic field tensors obtained by a direct boost [Formula: see text] and successive boosts [Formula: see text] and [Formula: see text] and check their consistency with Thomas rotation. This framework might be important to situations such as the calculation of frequency shifts for relativistic spin-1/2 particles undergoing Larmor precession in electromagnetic fields with small field non-uniformities.

SUBMITTER: Malhotra L

PROVIDER: S-EPMC7099098 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Lorentz microscopy of optical fields.

Project description:In electron microscopy, detailed insights into nanoscale optical properties of materials are gained by spontaneous inelastic scattering leading to electron-energy loss and cathodoluminescence. Stimulated scattering in the presence of external sample excitation allows for mode- and polarization-selective photon-induced near-field electron microscopy (PINEM). This process imprints a spatial phase profile inherited from the optical fields onto the wave function of the probing electrons. Here, we introduce Lorentz-PINEM for the full-field, non-invasive imaging of complex optical near fields at high spatial resolution. We use energy-filtered defocus phase-contrast imaging and iterative phase retrieval to reconstruct the phase distribution of interfering surface-bound modes on a plasmonic nanotip. Our approach is universally applicable to retrieve the spatially varying phase of nanoscale fields and topological modes.

| S-EPMC10582189 | biostudies-literature

Translation and Rotation of Transformation Media under Electromagnetic Pulse.

Project description:It is well known that optical media create artificial geometry for light, and curved geometry acts as an effective optical medium. This correspondence originates from the form invariance of Maxwell's equations, which recently has spawned a booming field called 'transformation optics'. Here we investigate responses of three transformation media under electromagnetic pulses, and find that pulse radiation can induce unbalanced net force on transformation media, which will cause translation and rotation of transformation media although their final momentum can still be zero. Therefore, the transformation media do not necessarily stay the same after an electromagnetic wave passes through.

| S-EPMC4913260 | biostudies-other

Effect of electromagnetic fields on the chondrogenic differentiation under microgravity conditions

Project description:A combination therapy of electromagnetic fields (EMF) and simulated microgravity (SMG) has not been examined in regenerative medicine of cartilage. In the present study, a bioreactor system using extremely low-frequency EMF and SMG was applied during the chondrogenic differentiation of human mesenchymal stem cells (hMSCs). It was hypothesized that a beneficial effect of EMF regarding chondrogenesis (COL2A) could be combined with an avoiding effect of SMG regarding hypertrophy (COLXA1) of cartilage. Pellet cultures of hMSCs formed cartilaginous tissue under the addition of growth factors (FGF; TGF-β3). Pure SMG reduced COLXA1 expression but also COL2A expression of hMSCs. Pure EMF showed no gene expression changes of hMSCs during chondrogenic differentiation. Combining EMF/SMG resulted in a re-increase of COL2A but did not reach control levels. The COL2A to COLXA1 ratio of combined EMF/SMG was not significantly different from control levels. The combination therapy of EMF/SMG did not significantly improve the chondrogenic potential of hMSCs.

2015-12-31 | GSE57298 | GEO

Effect of electromagnetic fields on the chondrogenic differentiation under microgravity conditions

Project description:A combination therapy of electromagnetic fields (EMF) and simulated microgravity (SMG) has not been examined in regenerative medicine of cartilage. In the present study, a bioreactor system using extremely low-frequency EMF and SMG was applied during the chondrogenic differentiation of human mesenchymal stem cells (hMSCs). It was hypothesized that a beneficial effect of EMF regarding chondrogenesis (COL2A) could be combined with an avoiding effect of SMG regarding hypertrophy (COLXA1) of cartilage. Pellet cultures of hMSCs formed cartilaginous tissue under the addition of growth factors (FGF; TGF-Î²3). Pure SMG reduced COLXA1 expression but also COL2A expression of hMSCs. Pure EMF showed no gene expression changes of hMSCs during chondrogenic differentiation. Combining EMF/SMG resulted in a re-increase of COL2A but did not reach control levels. The COL2A to COLXA1 ratio of combined EMF/SMG was not significantly different from control levels. The combination therapy of EMF/SMG did not significantly improve the chondrogenic potential of hMSCs. chondrogenic differentiation, electromagnetic stimulation-control, 1 timepoint with/without stimulation

2015-12-31 | E-GEOD-57298 | biostudies-arrayexpress

Electromagnetohydrodynamic modeling of Lorentz effect imaging.

Project description:Lorentz Effect Imaging (LEI) is an MRI technique that has been proposed for direct imaging of neuronal activity. While promising results have been obtained in phantoms and in the human median nerve in vivo, its contrast mechanism is still not fully understood. In this paper, computational model simulations were used to investigate how electromagnetohydrodynamics (EMHD) may explain the LEI contrast. Three computational models of an electrolyte-filled phantom subject to an applied current dipole, synchronized to oscillating magnetic field gradients of an LEI protocol, were developed to determine the velocity and displacement of water molecules as well as the resulting signal loss in an MR image. The simulated images were compared to images from previous LEI phantom experiments with identical properties for different stimulus current amplitudes and polarities. The first model, which evaluated ion trajectories based on Stokes flow using different mobility values, did not generate an appreciable signal loss due to an insufficient number of water molecules associated with the ion hydration shells. The second model, which computed particle drift based on the Lorentz force of charged particles in free space, was able to approximate the magnitude, but not the distribution of signal loss observed in the experimental images. The third model, which computed EMHD based on the Lorentz force and Navier-Stokes equations for flow of a conducting fluid, provided results consistent with both the magnitude and distribution of signal loss seen in the LEI experiments. Our EMHD model further yields information on electrical potential, velocity, displacement, and pressure, which are not readily available in an experiment, thereby providing a robust means to study and optimize LEI for imaging neuronal activity in the human cortex.

| S-EPMC3818387 | biostudies-literature

Effect of electromagnetic fields on human osteoarthritic and non-osteoarthritic chondrocytes.

Project description:Studies of the effects of electromagnetic fields (EMFs) on cartilaginous cells show a broad range of outcomes. However EMFs are not yet clinically applied as standard treatment of osteoarthritis, as EMF effects are showing varying outcomes in the literature. The aim of this study was to examine effects of EMFs (5 mT or 8 mT) on osteoarthritic (OA) and non-OA chondrocytes in order to investigate whether EMF effects are related to chondrocyte and EMF quality.Pellets of human OA and non-OA chondrocytes were exposed to a sinusoidal 15 Hz EMF produced by a solenoid. Control groups were cultivated without EMF under standard conditions for 7 days. Cultures were examined by staining, immunohistochemistry and quantitative real-time PCR for RNA corresponding to cartilage specific proteins (COL2A1, ACAN, SOX9).OA chondrocytes increased the expression of COL2A1 and ACAN under 5 mT EMF compared to control. In contrast no changes in gene expression were observed in non-OA chondrocytes. OA and non-OA chondrocytes showed no significant changes in gene expression under 8 mT EMF.A 5 mT EMF increased the expression of cartilage specific genes in OA chondrocytes whereas in non-OA chondrocytes no changes in gene expression were observed. An 8 mT EMF however showed no effect altogether. This suggests that EMF effects are related to EMF but also to chondrocyte quality. Further studies about the clinical relevance of this effect are necessary.

| S-EPMC5556359 | biostudies-other

Effect of Pulsed Electromagnetic Fields on Human Mesenchymal Stem Cells Using 3D Magnetic Scaffolds.

Project description:Alternative bone regeneration strategies that do not rely on harvested tissue or exogenous growth factors are needed. One of the major challenges in tissue reconstruction is recreating the bone tissue microenvironment using the appropriate combination of cells, scaffold, and stimulation to direct differentiation. This study presents a bone regeneration formulation that involves the use of human adipose-derived mesenchymal stem cells (hASCs) and a three-dimensional (3D) hydrogel scaffold based on self-assembled RADA16 peptides containing superparamagnetic iron oxide nanoparticles (NPs). Although superparamagnetic NPs could be used as stimulus to manipulate the cell proliferation and differentiation, in this paper their use is explored for assisting osteogenic differentiation of hASCs in conjunction with direct stimulation by extremely low-frequency pulsed electromagnetic fields (pEMFs). Cellular morphology, proliferation, and viability, as well as alkaline phosphatase activity, calcium deposition, and osteogenic capacity were monitored for cells cultured up to 21 days in the 3D construct. The results show that the pEMFs and NPs do not have any negative effect on cell viability, but instead distinctly induced early differentiation of hASCs to an osteoblastic phenotype, when compared with cells without biophysical stimulation. This effect is attributed to synergy between the pEMFs and NPs, which may have stimulated mechanotransduction pathways, which, in turn activated biochemical signals between cells to differentiate or proliferate. This approach may offer a safe and effective option for the treatment of non-union bone fractures. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.

| S-EPMC9290550 | biostudies-literature

Semi-quantitative proteomics of mammalian cells exposed to non-ionizing electromagnetic fields

Project description:Unbiased SILAC-based proteomics of human and mouse cells exposed to non-ionizing electromagnetic fields (EMFs) such as those emitted by power-lines (ELF), mobile cellular systems (UMTS) and wireless networking devices (WiFi).

2017-02-01 | PXD002862 | Pride

Probing the effect(s) of the microwaves' electromagnetic fields in enzymatic reactions.

Project description:This paper examines the effects that electromagnetic fields from microwave radiation have in enzymatic reactions. Hydrolysis of proteins in beef (in vivo case) and casein (in vitro case) by the papain enzyme, a major industrial enzyme, is used herein as a model reaction to assess, under highly controlled conditions, the various parameters of microwave radiation (electric field, magnetic field, pulsed microwave irradiation, continuous microwave irradiation) as they might influence these in vivo and in vitro enzymatic reactions. The effect(s) of the microwaves' electromagnetic fields was clearly evidenced in the in vivo case, contrary to the in vitro case where no such effect was observed, likely due to the nature of the hydrolysis reaction and to the autolysis (self-digestion) of the papain enzyme. Additionally, the effect of pulsed versus continuous microwave irradiation was further assessed by examining the catalase-assisted decomposition of hydrogen peroxide.

| S-EPMC6586677 | biostudies-other

Effect of low frequency electromagnetic fields on A2A adenosine receptors in human neutrophils.

Project description:The present study describes the effect of low frequency, low energy, pulsing electromagnetic fields (PEMFs) on A2A adenosine receptors in human neutrophils. Saturation experiments performed using a high affinity adenosine antagonist [3H]-ZM 241385 revealed a single class of binding sites in control and in PEMF-treated human neutrophils with similar affinity (KD=1.05+/-0.10 and 1.08+/-0.12 nM, respectively). Furthermore, after 1 h of exposure to PEMFs the receptor density was statistically increased (P<0.01) (Bmax =126+/-10 and 215+/-15 fmol mg-1 protein, respectively). The effect of PEMFs was specific to the A2A adenosine receptors. This effect was also intensity, time and temperature dependent. In the adenylyl cyclase assays the A2A receptor agonists, HE-NECA and NECA, increased cyclic AMP accumulation in untreated human neutrophils with an EC50 value of 43 (40 - 47) and 255 (228 - 284) nM, respectively. The capability of HE-NECA and NECA to stimulate cyclic AMP levels in human neutrophils was increased (P<0.01) after exposure to PEMFs with an EC50 value of 10(8 - 13) and 61(52 - 71) nM, respectively. In the superoxide anion (O2-) production assays HE-NECA and NECA inhibited the generation of O2- in untreated human neutrophils, with an EC50 value of 3.6(3.1 - 4.2) and of 23(20 - 27) nM, respectively. Moreover, in PEMF-treated human neutrophils, the same compounds show an EC50 value of 1.6(1.2 - 2.1) and of 6.0(4.7 - 7.5) nM respectively. These results indicate the presence of significant alterations in the expression and in the functionality of adenosine A2A receptors in human neutrophils treated with PEMFs.

| S-EPMC1762120 | biostudies-other

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data