Floquet Energies and Quantum Hall Effect in a Periodic Potential

The Quantum Hall Effect for free electrons in external periodic field is discussed without using the linear response approximation. We find that the Hall conductivity is related in a simple way to Floquet energies (associated to the Schroedinger equation in the co-moving frame). By this relation one can analyze the dependence of the Hall conductivity from the electric field. Sub-bands can be introduced by the time average of the expectation value of the Hamiltonian on the Floquet states. Moreover we prove previous results in form of sum rules as, for instance: the topological character of the Hall conductivity (being an integer multiple of e^2/h), the Diofantine equation which constrains the Hall conductivity by the rational number which measures the flux of the magnetic field through the periodicity cell. The Schroedinger equation fixes in a natural way the phase of the wave function over the reduced Brillouin zone: thus the topological invariant providing the Hall conductivity can be evaluated numerically without ambiguity.Comment: LaTex (revtex), 18 pages, 10 figures in .eps using epsf.sty. Changes in eq. (3.2). References adde

Section "Active, soft and magnetic matter": Abstract Book

This abstract book is made for the Active, soft and magnetic matter section of the 82nd International Scientific Conference of the University of Latvia, held on February 2, 2024. It is organized primarily by the MMML lab (Lab of Magnetic Soft Materials). The section includes reports on the latest developments in the research on magnetism and its interplay with active and soft systems.lzp-2021/1-0470, lzp-2020/1-0149, ES RTD/2022/1

Proceedings of the Scientific Workshop on the Health Effects of Electric and Magnetic Fields on Workers

"Participants in this workshop discussed various aspects of the health effects of worker exposure to electric and magnetic fields. Specific topics discussed included low frequency electromagnetic fields, biological effects of extremely low frequency electromagnetic fields, health effects of exposures, occupational exposure assessment for electric and magnetic fields in the 10 to 1000 hertz frequency range, and magnetic field management. Research recommendations from workshop panels concerning in-vitro/cellular mechanism studies, epidemiologic studies, exposure assessments, and methods for reducing exposures were provided." - NIOSHTIC-2Held Jan. 30-31, 1991, Cincinnati, Ohio.Also available via the World Wide Web.Includes bibliographical references

Charged Particles in a 2+1 Curved Background

The coupling to a 2+1 background geometry of a quantized charged test particle in a strong magnetic field is analyzed. Canonical operators adapting to the fast and slow freedoms produce a natural expansion in the inverse square root of the magnetic field strength. The fast freedom is solved to the second order. At any given time, space is parameterized by a couple of conjugate operators and effectively behaves as the `phase space' of the slow freedom. The slow Hamiltonian depends on the magnetic field norm, its covariant derivatives, the scalar curvature and presents a peculiar coupling with the spin-connection.Comment: 22 page

Variation in cardiovascular magnetic resonance myocardial contouring: Insights from an international survey.

LEVEL OF EVIDENCE: 5 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019

Breast imaging technology: Application of magnetic resonance imaging to early detection of breast cancer

Since its first introduction approximately 10 years ago, there has been extensive progress in the application of magnetic resonance imaging (MRI) to the detection and diagnosis of breast cancer. Contrast-enhanced MRI has been shown to have value in the diagnostic work-up of women who present with mammogram or clinical abnormalities. In addition, it has been demonstrated that MRI can detect mammogram occult multifocal cancer in patients who present with unifocal disease. Advances in risk stratification and limitations in mammography have stimulated interest in the use of MRI to screen high-risk women for cancer. Several studies of MRI high-risk screening are ongoing. Preliminary results are encouraging

The Death of Ferdinand De Saussure

I met Ferdinand de SaussureOn a night like thisOn love he said"I'm not so sureI even know what it isNo understandingNo closureIt is a nemesisYou can't use a bulldozerTo study orchids"He said...So we don't know anythingYou don't know anythingI don't know anythingabout loveBut we are nothingYou are nothingI am nothingWithout loveI'm just a great composerAnd not a violent manBut I lost my composureAnd I shot FerdinandCrying "it's well and kosherto say you don't understandbut this is for Holland-Dozier-Holland"His last words wereWe don't know anything…His fading words wereWe don't know anything

Northern/southern hemisphere asymmetry of sc/si in the nighttime sector

Magnetic field data from two pairs of conjugate stations along the 210°MM (Magnetic Meridian) are analyzed to re-examine characteristics of northern/southern hemisphere asymmetry of sc (sudden commencement)/si (sudden impulse) magnetic variations. We found that the seasonal variation of the asymmetry of sc/si can be seen even in the nighttime sector, where the ionospheric conductivity is much lower than that in the daytime sector. In order to interpret the observational fact, we have estimated the magnetic fields in the magnetosphere produced by the Chapman-Ferraro current (CF current) flowing at the dayside magnetopause, by using the Tsyganenko 96 model. It is found that the observed northern/southern hemisphere asymmetry of sc/si in the nighttime sector can be explained by invoking the seasonal variation in the tilt angle of Earth\u27s dipole axis