A Scenario to the Anomalous Hall Effect in the Mixed State of Superconductors

We argue that the motion of vacancies in a pinned vortex lattice may dominate the contribution to the Hall effect in an appropriate parameter regime for a superconductor. Based on this consideration a model is constructed to explain the anomalous Hall effect without any modification of the basic vortex dynamic equation. Quantitative predictions are obtained. Present model can be directly tested by an observation of the vacancy motion.Comment: latex, 6 pages (Presented at the Miami High Tc Conf., Jan 5-11, 1995. To appear at J. Supercond.

An architecture for interactive raster graphics

A radical reappraisal of the 3-D Interactive raster graphics pipeline has resulted In an experimental architecture for a workstation which is currently being evaluated at the CW!. The principal features of this architecture are that It: - concentrates exclusively on real-time interactive 3-D graphics (initially for CAD). - uses object space rather than Image space methods where possible. - avoids using a frame buffer. - only uses custom VLSI where commercial products are unlikely to suffice In the near term. Four years Into the project the system design Is complete and the major components have been acquired and the custom VLSI chips hove been packaged and tested. The current experience with the system is based on detailed simulations which gave a fairiy clear Idea on Its strengths and limitations. A complete, but reduced resolution, experimental prototype system is now being assembled

Larmor precession and tunneling time of a relativistic neutral spinning particle through an arbitrary potential barrier

The Larmor precession of a relativistic neutral spin-1/2 particle in a uniform constant magnetic field confined to the region of a one-dimensional arbitrary potential barrier is investigated. The spin precession serves as a clock to measure the time spent by a quantum particle traversing a potential barrier. With the help of general spin coherent state it is explicitly shown that the precession time is equal to the dwell time.Comment: 10 pages, 1 figure. To be published in Phys. Rev. A (01 February 2002

Nernst Effect in Electron-Doped Pr2−x_{2-x}Cex_{x}CuO4_4

The Nernst effect of Pr$_{2-x}$Ce$_{x}$CuO$_4$ (x=0.13, 0.15, and 0.17) has been measured on thin film samples between 5-120 K and 0-14 T. In comparison to recent measurements on hole-doped cuprates that showed an anomalously large Nernst effect above the resistive T$_c$ and H$_{c2}$ \cite{xu,wang1,wang2,capan}, we find a normal Nernst effect above T$_c$ and H$_{c2}$ for all dopings. The lack of an anomalous Nernst effect in the electron-doped compounds supports the models that explain this effect in terms of amplitude and phase fluctuations in the hole-doped cuprates. In addition, the H$_{c2}$(T) determined from the Nernst effect shows a conventional behavior for all dopings. The energy gap determined from H$_{c2}$(0) decreases as the system goes from under-doping to over-dopingin agreement with the recent tunnelling experiments

Морфология и трехмерные изображения рудника-пещеры Кан-и-Гут

Путём сравнительного анализа и компьютерной обработки данных чертежей и схем из разных источников впервые получена пространственная (3D) модель одного из самых сложных в морфологическом отношении подземелий смешанного типа – рудника-пещеры Кан-и-Гут (Кыргызстан). Описана методика перевода графических данных в цифровой формат. Найдены основные морфометрические параметры полости, представлены трехмерные изображения основных его отделов, обсуждается их морфология. В ряде полостей рудника-пещеры выявлены существенные изменения, произошедшие за последние 50 лет вследствие масштабных обрушений.Шляхом порівняльного аналізу і комп’ютерної обробки даних креслень і схем з різних джерел вперше отримана просторова (3d) модель одного з найскладніших в морфологічному відношенні підземель змішаного типа – копальні-печери Кан-і-Гут (Киргизстан). Описана методика переведення графічних даних в цифровий формат. Знайдені основні морфометричні параметри порожнини, представлені тривимірні зображення основних його відділів, обговорюється їх морфологія. У ряді порожнин копальні-печери виявлені істотні зміни, події за останніх 50 років унаслідок масштабних обвалень.Kan-i-Gut mined cave, located in Kyrgyzstan, is one of the most morphologically complex cavities of mixed genesis. For the first time, a 3D model was developed for this cave by comparative analyses and computer processing of cave maps and mine surveyor plan and profile, obtained from different sources. The methodology of transferring graphical data into digital format is described. Primary morphometric parameters of the mined cave are gathered, and 3D images of its main parts are presented. Essential morphological changes due to vast collapses during the last 50 years were discovered

Nernst Effect of stripe ordering La1.8−x_{1.8-x}Eu0.2_{0.2}Srx_xCuO4_4

We investigate the transport properties of La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ ($x=0.04$, 0.08, 0.125, 0.15, 0.2) with a special focus on the Nernst effect in the normal state. Various anomalous features are present in the data. For $x=0.125$ and 0.15 a kink-like anomaly is present in the vicinity of the onset of charge stripe order in the LTT phase, suggestive of enhanced positive quasiparticle Nernst response in the stripe ordered phase. At higher temperature, all doping levels except $x=0.2$ exhibit a further kink anomaly in the LTO phase which cannot unambiguously be related to stripe order. Moreover, a direct comparison between the Nernst coefficients of stripe ordering La$_{1.8-x}$Eu$_{0.2}$Sr$_x$CuO$_4$ and superconducting La$_{2-x}$Sr$_x$CuO$_4$ at the doping levels $x=0.125$ and $x=0.15$ reveals only weak differences. Our findings make high demands on any scenario interpreting the Nernst response in hole-doped cuprates

Self-dual noncommutative \phi^4-theory in four dimensions is a non-perturbatively solvable and non-trivial quantum field theory

We study quartic matrix models with partition function Z[E,J]=\int dM \exp(trace(JM-EM^2-(\lambda/4)M^4)). The integral is over the space of Hermitean NxN-matrices, the external matrix E encodes the dynamics, \lambda>0 is a scalar coupling constant and the matrix J is used to generate correlation functions. For E not a multiple of the identity matrix, we prove a universal algebraic recursion formula which gives all higher correlation functions in terms of the 2-point function and the distinct eigenvalues of E. The 2-point function itself satisfies a closed non-linear equation which must be solved case by case for given E. These results imply that if the 2-point function of a quartic matrix model is renormalisable by mass and wavefunction renormalisation, then the entire model is renormalisable and has vanishing \beta-function. As main application we prove that Euclidean \phi^4-quantum field theory on four-dimensional Moyal space with harmonic propagation, taken at its self-duality point and in the infinite volume limit, is exactly solvable and non-trivial. This model is a quartic matrix model, where E has for N->\infty the same spectrum as the Laplace operator in 4 dimensions. Using the theory of singular integral equations of Carleman type we compute (for N->\infty and after renormalisation of E,\lambda) the free energy density (1/volume)\log(Z[E,J]/Z[E,0]) exactly in terms of the solution of a non-linear integral equation. Existence of a solution is proved via the Schauder fixed point theorem. The derivation of the non-linear integral equation relies on an assumption which we verified numerically for coupling constants 0<\lambda\leq (1/\pi).Comment: LaTeX, 64 pages, xypic figures. v4: We prove that recursion formulae and vanishing of \beta-function hold for general quartic matrix models. v3: We add the existence proof for a solution of the non-linear integral equation. A rescaling of matrix indices was necessary. v2: We provide Schwinger-Dyson equations for all correlation functions and prove an algebraic recursion formula for their solutio

Diagnostic exome sequencing in 266 Dutch patients with visual impairment

Inherited eye disorders have a large clinical and genetic heterogeneity, which makes genetic diagnosis cumbersome. An exome-sequencing approach was developed in which data analysis was divided into two steps: the vision gene panel and exome analysis. In the vision gene panel analysis, variants in genes known to cause inherited eye disorders were assessed for pathogenicity. If no causative variants were detected and when the patient consented, the entire exome data was analyzed. A total of 266 Dutch patients with different types of inherited eye disorders, including inherited retinal dystrophies, cataract, developmental eye disorders and optic atrophy, were investigated. In the vision gene panel analysis (likely), causative variants were detected in 49% and in the exome analysis in an additional 2% of the patients. The highest detection rate of (likely) causative variants was in patients with inherited retinal dystrophies, for instance a yield of 63% in patients with retinitis pigmentosa. In patients with developmental eye defects, cataract and optic atrophy, the detection rate was 50, 33 and 17%, respectively. An exome-sequencing approach enables a genetic diagnosis in patients with different types of inherited eye disorders using one test. The exome approach has the same detection rate as targeted panel sequencing tests, but offers a number of advantages. For instance, the vision gene panel can be frequently and easily updated with additional (novel) eye disorder genes. Determination of the genetic diagnosis improved the clinical diagnosis, regarding the assessment of the inheritance pattern as well as future disease perspective

The complex variability of blazars: time-scales and periodicity analysis in S4 0954+65

Among active galactic nuclei, blazars show extreme variability properties. We here investigate the case of the BL Lac object S4 0954+65 with data acquired in 2019–2020 by the Transiting Exoplanet Survey Satellite (TESS) and by the Whole Earth Blazar Telescope (WEBT) Collaboration. The 2-min cadence optical light curves provided by TESS during three observing sectors of nearly 1 month each allow us to study the fast variability in great detail. We identify several characteristic short-term time-scales, ranging from a few hours to a few days. However, these are not persistent, as they differ in the various TESS sectors. The long-term photometric and polarimetric optical and radio monitoring undertaken by the WEBT brings significant additional information, revealing that (i) in the optical, long-term flux changes are almost achromatic, while the short-term ones are strongly chromatic; (ii) the radio flux variations at 37 GHz follow those in the optical with a delay of about 3 weeks; (iii) the range of variation of the polarization degree and angle is much larger in the optical than in the radio band, but the mean polarization angles are similar; (iv) the optical long-term variability is characterized by a quasi-periodicity of about 1 month. We explain the source behaviour in terms of a rotating inhomogeneous helical jet, whose pitch angle can change in time.Accepted manuscrip

An architecture for interactive raster graphics

A radical reappraisal of the 3-D Interactive raster graphics pipeline has resulted In an experimental architecture for a workstation which is currently being evaluated at the CW!. The principal features of this architecture are that It: - concentrates exclusively on real-time interactive 3-D graphics (initially for CAD). - uses object space rather than Image space methods where possible. - avoids using a frame buffer. - only uses custom VLSI where commercial products are unlikely to suffice In the near term. Four years Into the project the system design Is complete and the major components have been acquired and the custom VLSI chips hove been packaged and tested. The current experience with the system is based on detailed simulations which gave a fairiy clear Idea on Its strengths and limitations. A complete, but reduced resolution, experimental prototype system is now being assembled