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1.
Nature ; 579(7798): 205-209, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32161384

RESUMEN

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers1 and demonstrations of quantum search2 and factoring3 algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron4-6. However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods7-9 relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single 123Sb (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 196110 but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots11,12 could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.


Asunto(s)
Modelos Teóricos , Silicio/química , Fenómenos Electromagnéticos , Electrones , Puntos Cuánticos/química
2.
Urology ; 136: 270-271, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-32033678
3.
Phys Chem Chem Phys ; 22(4): 2188-2192, 2020 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-31912828

RESUMEN

The interplay between multiple chromophores in nucleic acids and photosynthetic proteins gives rise to complex electronic phenomena and largely governs the de-excitation dynamics. Electronic coupling between bases in the excited states of single strands of DNA and RNA may extend over several bases and likely protects nucleic acids from harmful UV damage. Here we report on the coupling between bases in single RNA strands of cytosine and find that the excited state is delocalized over up to five bases at neutral pH, where all bases are non-protonated (i.e. neutral). Delocalization is over four bases at 278 nm excitation, while it involves five bases at shorter wavelengths of 188 nm and 201 nm. This is in contrast to only nearest-neighbour interactions for corresponding DNA strands as previously reported. The current results seemingly corroborate earlier findings of larger spatial communication in RNA than in DNA strands of adenine, but there is no obvious link between the overall structure of strands and delocalization lengths. RNA cytosine strands form a tight helix, while comparatively, adenine strands show less tight packing, also compared to their DNA counterparts, and yet exhibit even higher delocalisation.


Asunto(s)
Citosina/química , Citosina/efectos de la radiación , ARN/química , ARN/efectos de la radiación , Fenómenos Electromagnéticos , Conformación de Ácido Nucleico/efectos de la radiación , Rayos Ultravioleta
4.
Adv Exp Med Biol ; 1232: 99-104, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-31893400

RESUMEN

The incidence of stress-induced psychological and somatic diseases has been increasing rapidly, and it is important to clarify the neurophysiological mechanisms of stress response in order to establish effective stress management methods. We previously reported that the prefrontal cortex (PFC) plays an important role in stress response. In the present study, we employed near-infrared spectroscopy (NIRS) and electroencephalography (EEG) to investigate the characteristics of PFC activity during mental arithmetic tasks. A two-channel NIRS device was used to measure hemoglobin (Hb) concentration changes in the bilateral PFC during a mental arithmetic task (2 min) in normal adults. Simultaneously, EEG was used to also measure bilateral PFC activity during the same task. We evaluated concentration changes of oxy-Hb induced by the task while analyzing α wave changes using power spectrum analysis. It was observed that oxy-Hb in the bilateral PFC increased significantly during the task (p < 0.05), while α wave power in the PFC decreased significantly (p < 0.01). The present results indicate that mental stress tasks caused the activation of the bilateral PFC. Simultaneous measurements of NIRS and EEG are useful for evaluating the neurophysiological mechanism of stress responses in the brain.


Asunto(s)
Electroencefalografía , Fenómenos Electromagnéticos , Oxígeno , Espectroscopía Infrarroja Corta , Estrés Psicológico , Adulto , Hemoglobinas/análisis , Humanos , Oxígeno/sangre , Oxihemoglobinas/análisis , Corteza Prefrontal/fisiopatología , Estrés Psicológico/fisiopatología
6.
Magy Onkol ; 63(4): 354-358, 2019 Dec 09.
Artículo en Húngaro | MEDLINE | ID: mdl-31821390

RESUMEN

Our objective was to develop an electromagnetic tumor therapy device in a consortial cooperation between Semmelweis University and Oncotherm Ltd., to provide data and contribute to the development of the next generation of devices through preclinical, clinical and developmental modules via in vivo, in vitro studies, and patient treatments. Our numerous preclinical studies support the efficacy of mEHT. Clinical treatments were performed in 181 patients with inoperable and/or oligometastatic solid tumors. The protocols were developed, an international guideline was completed, and the planned steps of device development were realized. By optimizing previous selective RF techniques based on recent research findings, we can provide the most modern evidence-based treatment in the future.


Asunto(s)
Neoplasias , Fenómenos Electromagnéticos , Humanos
7.
Zhongguo Yi Liao Qi Xie Za Zhi ; 43(6): 439-441, 2019 Nov 30.
Artículo en Chino | MEDLINE | ID: mdl-31854532

RESUMEN

In view of the background that the regulation of medical device supervision and management is about to cancel the registration and inspection, this paper analyses the risk of electromagnetic compatibility of medical devices, combs the current situation of electromagnetic compatibility testing, discusses the factors to be considered in the approval of third-party testing reports, and gives relevant solutions suitable for China's national conditions.


Asunto(s)
Estudios de Factibilidad , China , Fenómenos Electromagnéticos
8.
J Vet Sci ; 20(5): e51, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31565894

RESUMEN

In ultrasound/computed tomography (CT) fusion images, ultrasound allows visualization of the target in real time. CT provides a navigation for ultrasound scanning and improves the overview in areas of limited visualization with ultrasound. This study was performed to investigate the feasibility of ultrasound/CT fusion based on an electromagnetic tracking technique using external fiducial markers for canine ocular and periocular regions. In 7 Beagle dogs, contrast-enhanced CT images of the head were obtained with placing external fiducial markers over the frontal region and both sides of the forepaws of the dog. Ultrasonography was performed under a magnetic field by installing a position sensor in the linear probe, without changing the dog's position. The positions of the external fiducial markers were adjusted and matched, based on the CT images. The execution time of co-registration and the distance between the regions of interest and the co-registration points, the frontal bone, cornea, retina, and optic nerve, were estimated. Approximately 60% of external fiducial markers were properly recognized in all dogs. After adjustment, all external fiducial markers were precisely matched. The co-registration execution time was less than 1 min. The distances between the regions of interest and co-registration points were less than 3 mm in all dogs. The electromagnetic tracking technique using external fiducial markers was a simple and applicable method for fusion imaging of a canine head using real-time ultrasonography and CT. This technique can be useful for interventional procedures of retrobulbar and periorbital lesions.


Asunto(s)
Ojo/diagnóstico por imagen , Marcadores Fiduciales/veterinaria , Tomografía Computarizada por Rayos X/veterinaria , Ultrasonografía/veterinaria , Animales , Perros , Fenómenos Electromagnéticos , Masculino , Tomografía Computarizada por Rayos X/métodos , Ultrasonografía/métodos
9.
Nat Commun ; 10(1): 4405, 2019 09 27.
Artículo en Inglés | MEDLINE | ID: mdl-31562319

RESUMEN

The emergence of smart electronics, human friendly robotics and supplemented or virtual reality demands electronic skins with both tactile and touchless perceptions for the manipulation of real and virtual objects. Here, we realize bifunctional electronic skins equipped with a compliant magnetic microelectromechanical system able to transduce both tactile-via mechanical pressure-and touchless-via magnetic fields-stimulations simultaneously. The magnetic microelectromechanical system separates electric signals from tactile and touchless interactions into two different regions, allowing the electronic skins to unambiguously distinguish the two modes in real time. Besides, its inherent magnetic specificity overcomes the interference from non-relevant objects and enables signal-programmable interactions. Ultimately, the magnetic microelectromechanical system enables complex interplay with physical objects enhanced with virtual content data in augmented reality, robotics, and medical applications.


Asunto(s)
Fenómenos Fisiológicos de la Piel , Percepción del Tacto/fisiología , Tacto , Dispositivos Electrónicos Vestibles , Algoritmos , Electricidad , Fenómenos Electromagnéticos , Electrónica/instrumentación , Electrónica/métodos , Humanos , Magnetismo , Robótica , Transductores
10.
IEEE Int Conf Rehabil Robot ; 2019: 163-168, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31374624

RESUMEN

Freedom of neck range of motion has been identified for decades as an important indicator of neck health. In the past, neck motion has been measured in clinical settings using straight-plane movements that do not represent real-world 'ecological' performance. The tools currently used are low-fidelity analog or digital tools that rely greatly on the orientation of the person with respect to gravity, or the evaluator's ability to accurately align protractor arms with key surface markers for angle measurement. A possible solution lies in the use of wearable sensors for tracking the motion of the neck without clinical instruction. For this purpose, the focus of this paper is on the assessment of a commercially available stretch sensitive sensor, C-Stretch® against a gold standard for motion tracking. The sensor's accuracy and agreement for measuring neck rotations were evaluated. The results show that the stretch sensitive sensor was accurate with an average RMSE of 5.86° (SD=$4.38^{\circ}, \mathrm{n}=2$) and highly correlated $r=0.88-0.99,(p\lt0.01)$ with Aurora, an electromagnetic tracking system. This work may lead to using wearable sensors as a cost-effective, lightweight, and safe alternative to assess real-world neck range of motion for clinical application.


Asunto(s)
Capacidad Eléctrica , Movimiento , Cuello/fisiología , Rotación , Electrodos , Fenómenos Electromagnéticos , Humanos , Rango del Movimiento Articular
11.
Int J Nanomedicine ; 14: 5799-5816, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31440048

RESUMEN

Purpose: Bone consolidation after severe trauma is the most challenging task in orthopedic surgery. This study aimed to develop biomimetic composite for coating Ti implants. Afterwards, these implants were tested in vivo to assess bone consolidation in the absence or the presence of high-frequency pulsed electromagnetic short-waves (HF-PESW). Materials: Biomimetic coating was successfully developed using multi-substituted hydroxyapatite (ms-HAP) functionalized with collagen (ms-HAP/COL), embedded into poly-lactic acid (PLA) matrix (ms-HAP/COL@PLA), and subsequently covered with self-assembled COL layer (ms-HAP/COL@PLA/COL, named HAPc). Methods: For in vivo evaluation, 32 Wistar albino rats were used in four groups: control group (CG) with Ti implant; PESW group with Ti implant+HF-PESW; HAPc group with Ti implant coated with HAPc; HAPc+PESW group with Ti implant coated with HAPc+HF-PESW. Left femoral diaphysis was fractured and fixed intramedullary. From the first post-operative day, PESW and HAPc+PESW groups underwent HF-PESW stimulation for 14 consecutive days. Biomimetic coating was characterized by XRD, HR-TEM, SEM, EDX and AFM. Results: Osteogenic markers (ALP and osteocalcin) and micro-computed tomography (CT) analysis (especially bone volume/tissue volume ratio results) indicated at 2 weeks the following group order: HAPc+PESW>HAPc≈PESW (P>0.05) and HAPc+PESW>control (P<0.05), indicating the higher values in HAPc+PESW group compared to CG. The fracture-site bone strength showed, at 2 weeks, the highest average value in HAPc+PESW group. Moreover, histological analysis revealed the most abundant COL fibers assembled in dense bundles in HAPc-PESW group. At 8 weeks, micro-CT indicated higher values only in HAPc+PESW group vs CG (P<0.05), and histological results showed a complete-healed fracture in groups: HAPc+PESW, HAPc and PESW, but with more advanced bone remodeling in HAPc+PESW group. Conclusion: Using Ti implants coated by HAPc jointly with HF-PESW stimulation positively influenced the bone consolidation process, especially in its early phase, thus potentially providing a superior strategy for clinical applications.


Asunto(s)
Materiales Biomiméticos/farmacología , Huesos/efectos de los fármacos , Materiales Biocompatibles Revestidos/farmacología , Fenómenos Electromagnéticos , Poliésteres/química , Prótesis e Implantes , Titanio/farmacología , Animales , Biomarcadores/sangre , Fenómenos Biomecánicos , Bovinos , Colágeno/farmacología , Durapatita/farmacología , Fémur/efectos de los fármacos , Osteogénesis/efectos de los fármacos , Ratas Wistar , Propiedades de Superficie , Microtomografía por Rayos X
12.
Phys Chem Chem Phys ; 21(29): 16198-16206, 2019 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-31298234

RESUMEN

The secondary structure of proteins is of prime importance to their proper functioning and protein misfolding may cause serious disorders in the human body. Here, the electric field influence on the conformational stability of model alpha helical peptides is studied by employing density functional theory calculations combined with continuum dielectric method computations. Our results show that the basic parameters of the electric field - its strength and directionality - are determinative for the alpha helix stability. An electric field strength of 0.005 a.u. (2.5 V nm-1) applied along the X coordinate axis (the long axis of the helix) in the direction of the µx component of the molecular dipole moment does affect the peptide conformation, destroys the helix, and leads to the formation of a cyclic-peptide-like structure. Interestingly, the process of denaturation can be reversible when the electric field is switched-off. The reversibility of the process of the electric field induced disruption of the peptide secondary structure suggests a possible mechanism for the healing of misfolded proteins.


Asunto(s)
Fenómenos Electromagnéticos , Modelos Químicos , Péptidos/química , Péptidos/efectos de la radiación , Conformación Proteica en Hélice alfa , Pliegue de Proteína/efectos de la radiación
13.
Radiat Oncol ; 14(1): 124, 2019 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-31296231

RESUMEN

BACKGROUND: Stereotactic ablative radiotherapy (SABR) is a treatment option for patients with early stage non-small cell lung cancer (NSCLC) and recurrent or oligometastatic disease who are not surgical candidates. Due to the continuous motion of tumors within the lungs, implementing a strategy to track the target lesion is crucial. One method is to place fiducial markers which the robotic SABR system is able to track during treatment. However, placing these markers in a manner that maximizes tracking efficacy can be challenging. Using a novel fiducial placement guidance system (FPGS) during fiducial deployment may offer a way to improve the quantity of fiducials tracked by the robotic SABR system. METHOD: This was an institutional, retrospective review identifying all patients who received robotic SABR for lung tumors from May 2015 until January 2017. The FPGS was instituted in May 2016. The median number of fiducials tracked and the rate of complication was compared between patients whose fiducials were placed using FPGS versus those that were not. RESULTS: A total of 128 patients with 147 treated lung lesions were identified. Of the lesions that utilized FPGS (n = 44), 28 had 2 tracked fiducials (63.6%), 14 had 3 (31.8%) and 2 had 4 (4.6%). Of the lesions treated without FPGS (n = 103), 5 had 1 tracked fiducial (4.9%), 91 had 2 (88.4%), 6 had 3 (5.8%), and 2 had 4 (1.9%). A significant improvement in the median number of fiducials tracked per fraction was observed for the lesions with fiducials placed using FPGS on Wilcoxon rank sum test (p < 0.001). The rate of complication was low and not statistically different between cohorts (p = 0.44). CONCLUSIONS: The FPGS can be used during the deployment of fiducial markers and may increase the number of fiducials tracked. TRIAL REGISTRATION: An exemption for this retrospective review was granted by the East Carolina University IRB under UMCIRB 15-001726.


Asunto(s)
Broncoscopía/métodos , Carcinoma de Pulmón de Células no Pequeñas/cirugía , Marcadores Fiduciales , Neoplasias Pulmonares/cirugía , Monitoreo Fisiológico , Radiocirugia/métodos , Mecánica Respiratoria , Fenómenos Electromagnéticos , Humanos , Movimiento , Planificación de la Radioterapia Asistida por Computador/métodos , Técnicas de Imagen Sincronizada Respiratorias , Estudios Retrospectivos
14.
Sensors (Basel) ; 19(13)2019 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-31288428

RESUMEN

This paper presents a mathematical model of measuring blood flow based on electromagnetic induction for predicting the rate of arterial stenosis. Firstly, an electrode sensor was used to collect the induced potential differences from human skin surface in a uniform magnetic field. Then, the inversion matrix was constructed by the weight function theory and finite element method. Next, the blood flow volume inversion model was constructed by combining the induction potential differences and inversion matrix. Finally, the rate of arterial stenosis was predicted based on mathematical relationship between blood flow and the area of arterial stenosis. To verify the accuracy of the model, a uniform magnetic field distribution of Helmholtz coil and a 3D geometric model of the ulnar artery of the forearm with different rates of stenosis were established in COMSOL, a finite element analysis software. Simulation results showed that the inversion model had high accuracy in the measurement of blood flow and the prediction of rate of stenosis, and is of great significance for the early diagnosis of arterial stenosis and other vessel diseases.


Asunto(s)
Arterias/fisiopatología , Fenómenos Electromagnéticos , Modelos Cardiovasculares , Enfermedades Vasculares/sangre , Simulación por Computador , Constricción Patológica , Diseño de Equipo , Análisis de Elementos Finitos , Humanos , Modelos Lineales , Flujo Sanguíneo Regional , Programas Informáticos
15.
J Med Eng Technol ; 43(3): 165-172, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31313608

RESUMEN

Hyperthermia is potentially an effective method for the treatment of cancer tumours. In the present manuscript, improvement in the treatment of liver cancer through electromagnetic heating is studied using high dielectric material through mathematical modelling in COMSOL Multiphysics. It is observed from the result that without increasing the power input, intensity of the temperature can be increased by changing the dielectric constant. Treatment time in ablation of the liver tumour can also be reduced. Results are obtained for total power dissipation density, heat flux, temperature distribution and fraction of necrosis tissue.


Asunto(s)
Calefacción , Hipertermia Inducida/métodos , Neoplasias Hepáticas/terapia , Microondas/uso terapéutico , Fenómenos Electromagnéticos , Humanos , Modelos Teóricos , Temperatura Ambiental
16.
Chemosphere ; 236: 124302, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31306974

RESUMEN

A pulsed corona discharge above liquid combined with ozonation has been investigated for the degradation of organic pollutants in water, as well as regarding the generation of several oxidizing species: ozone in gas phase, hydrogen peroxide and hydroxyl radicals in the liquid. A considerable improvement in the energy efficiency for organic compounds removal has been observed when reducing the width of the discharge pulses. This finding was correlated with the efficient formation of oxidizing species in case of short pulses. Recycling of the effluent gas from the plasma also enhances contaminants degradation. This was mainly attributed to an in situ peroxone process, i.e. the reaction between plasma-generated O3 and H2O2, forming highly reactive OH radicals, largely responsible for organic compounds degradation. This assumption is supported by the decline in O3 and H2O2 concentrations and simultaneous increase in OH concentration detected in plasma-ozonation experiments as compared to results obtained with plasma alone.


Asunto(s)
Fenómenos Electromagnéticos , Peróxido de Hidrógeno/análisis , Radical Hidroxilo/análisis , Ozono/análisis , Contaminantes Químicos del Agua/análisis , Purificación del Agua/métodos , Electricidad , Peróxido de Hidrógeno/química , Radical Hidroxilo/química , Oxidación-Reducción , Ozono/química , Agua/química
17.
Bioelectromagnetics ; 40(6): 402-411, 2019 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31310336

RESUMEN

This article presents the pre-clinical evaluation of our custom-built, single-band microwave radiometer centered at 1.3 GHz for deep tissue thermometry, and a pilot study on volunteers for passive detection of inflammation in knee joints. The electromagnetic (EM) compatibility of the battery-operated radiometer for clinical use was assessed as per International Special Committee on Radio Interference (CISPR) 22 standard. The ability to detect inflammation in knee joints was assessed using a substrate integrated waveguide antenna connected to the radiometer. EM compatibility tests carried out in the laboratory indicated device immunity to intentional radiated interference up to -20 dBm injected power in the global system for mobile communication frequency band, and pre-compliance to CISPR 22 standard. Radiometer temperature measurements recorded at the lateral and medial aspects of both knees of 41 volunteers indicated mean temperature greater than 33°C for the diseased sites compared with the mean temperature of 28°C measured for the healthy sites. One-way analysis of variance statistics indicated significantly (P < 0.005) higher radiometer temperature at the diseased sites unlike the healthy sites. Thus, the EM pre-compliance of the device and the potential to measure deep tissue inflammation were demonstrated. Bioelectromagnetics. 2019;40:402-411. © 2019 Bioelectromagnetics Society.


Asunto(s)
Inflamación/diagnóstico , Articulación de la Rodilla/metabolismo , Microondas , Adulto , Fenómenos Electromagnéticos , Femenino , Calor , Humanos , Masculino , Persona de Mediana Edad , Proyectos Piloto , Radiometría/instrumentación , Termometría/instrumentación
18.
Sensors (Basel) ; 19(12)2019 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-31212999

RESUMEN

Breath gas analysis is a promising tool for medical research and diagnosis. A particularly powerful technological approach is millimeter-wave/terahertz (mmW/THz) spectroscopy, because it is a very sensitive and highly selective technique. In addition, it offers the potential for compact and affordable sensing systems for wide use. In this work, we demonstrate the capability of a mmW/THz spectrometer for breath analysis. Samples from three volunteers and a sample from ambient air were analyzed with respect to 31 different molecular species. High-resolution absorption spectra were measured by scanning two absorption lines from each species. Out of the 31, a total of 21 species were detected. The results demonstrate the potential of mmW/THz spectroscopy for breath analysis.


Asunto(s)
Pruebas Respiratorias/métodos , Gases/análisis , Espectroscopía de Terahertz/métodos , Fenómenos Electromagnéticos , Humanos , Refractometría/métodos
19.
Physiol Res ; 68(4): 611-622, 2019 08 29.
Artículo en Inglés | MEDLINE | ID: mdl-31177802

RESUMEN

Effects of low-frequency electromagnetic fields (LF EMF) on the activation of different tissue recovery processes have not yet been fully understood. The detailed quantification of LF EMF effects on the angiogenesis were analysed in our experiments by using cultured human and mouse endothelial cells. Two types of fields were used in the tests as follows: the LF EMF with rectangular pulses, 340-microsecond mode at a frequency of 72 Hz and peak intensity 4 mT, and the LF EMF with sinusoidal alternating waveform 5 000 Hz, amplitude-modulated by means of a special interference spectrum mode set to a frequency linear sweep from 1 to 100 Hz for 6 s and from 100 Hz to 1 Hz return also for 6 s, swing period of 12 second. Basic parameters of cultured cells measured after the LF EMF stimulus were viability and proliferation acceleration. Both types of endothelial cells (mouse and human ones) displayed significant changes in the proliferation after the application of the LF EMF under conditions of a rectangular pulse mode. Based on the results, another test of the stimulation on a more complex endothelial-fibroblast coculture model will be the future step of the investigation.


Asunto(s)
Supervivencia Celular/fisiología , Campos Electromagnéticos , Células Endoteliales de la Vena Umbilical Humana/fisiología , Animales , Células Cultivadas , Fenómenos Electromagnéticos , Células Endoteliales/fisiología , Humanos , Ratones
20.
Proc Jpn Acad Ser B Phys Biol Sci ; 95(6): 278-289, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31189780

RESUMEN

Electrons in solids constitute quantum many-body systems showing a variety of phenomena. It often happens that the eigen states of the Hamiltonian are classified into subgroups separated by energy gaps. Band structures in solids and spin polarization in Mott insulators are two representative examples. The subspace spanned by these wavefunctions belonging to each of this subgroup can be regarded as a manifold in Hilbert space, and concepts concerning differential geometry become relevant. Connection and curvature are two key quantities, which correspond to the vector potential and field strength of electromagnetism, respectively. Therefore, one can construct an effective electromagnetic field from the structure of the Hilbert space, which is called an "emergent electromagnetic field". In this article, we review the physics related to this emergent electromagnetic field in solids, including the gauge theory of strongly correlated electrons, various Hall effects, multiferroics, topological matter, magnetic texture such as skyrmions, and the shift current in noncentrosymmetric materials.


Asunto(s)
Fenómenos Electromagnéticos , Teoría Cuántica , Electrones
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