Maximum Coronal Mass Ejection Speed as an Indicator of Solar and Geomagnetic Activities

We investigate the relationship between the monthly averaged maximal speeds of coronal mass ejections (CMEs), international sunspot number (ISSN), and the geomagnetic Dst and Ap indices covering the 1996-2008 time interval (solar cycle 23). Our new findings are as follows. (1) There is a noteworthy relationship between monthly averaged maximum CME speeds and sunspot numbers, Ap and Dst indices. Various peculiarities in the monthly Dst index are correlated better with the fine structures in the CME speed profile than that in the ISSN data. (2) Unlike the sunspot numbers, the CME speed index does not exhibit a double peak maximum. Instead, the CME speed profile peaks during the declining phase of solar cycle 23. Similar to the Ap index, both CME speed and the Dst indices lag behind the sunspot numbers by several months. (3) The CME number shows a double peak similar to that seen in the sunspot numbers. The CME occurrence rate remained very high even near the minimum of the solar cycle 23, when both the sunspot number and the CME average maximum speed were reaching their minimum values. (4) A well-defined peak of the Ap index between 2002 May and 2004 August was co-temporal with the excess of the mid-latitude coronal holes during solar cycle 23. The above findings suggest that the CME speed index may be a useful indicator of both solar and geomagnetic activities. It may have advantages over the sunspot numbers, because it better reflects the intensity of Earth-directed solar eruptions

Parameters of the Magnetic Flux inside Coronal Holes

Parameters of magnetic flux distribution inside low-latitude coronal holes (CHs) were analyzed. A statistical study of 44 CHs based on Solar and Heliospheric Observatory (SOHO)/MDI full disk magnetograms and SOHO/EIT 284\AA images showed that the density of the net magnetic flux, $B_{{\rm net}}$, does not correlate with the associated solar wind speeds, $V_x$. Both the area and net flux of CHs correlate with the solar wind speed and the corresponding spatial Pearson correlation coefficients are 0.75 and 0.71, respectively. A possible explanation for the low correlation between $B_{{\rm net}}$ and $V_x$ is proposed. The observed non-correlation might be rooted in the structural complexity of the magnetic field. As a measure of complexity of the magnetic field, the filling factor, $f(r)$, was calculated as a function of spatial scales. In CHs, $f(r)$ was found to be nearly constant at scales above 2 Mm, which indicates a monofractal structural organization and smooth temporal evolution. The magnitude of the filling factor is 0.04 from the Hinode SOT/SP data and 0.07 from the MDI/HR data. The Hinode data show that at scales smaller than 2 Mm, the filling factor decreases rapidly, which means a mutlifractal structure and highly intermittent, burst-like energy release regime. The absence of necessary complexity in CH magnetic fields at scales above 2 Mm seems to be the most plausible reason why the net magnetic flux density does not seem to be related to the solar wind speed: the energy release dynamics, needed for solar wind acceleration, appears to occur at small scales below 1 Mm.Comment: 6 figures, approximately 23 pages. Accepted in Solar Physic

Current Helicity and Twist as Two Indicators of The Mirror Asymmetry of solar Magnetic Fields

A comparison between the two tracers of magnetic field mirror asymmetry in solar active regions, twist and current helicity, is presented. It is shown that for individual active regions these tracers do not possess visible similarity while averaging by time over the solar cycle, or by latitude, reveals similarities in their behaviour. The main property of the dataset is anti-symmetry over the solar equator. Considering the evolution of helical properties over the solar cycle we find signatures of a possible sign change at the beginning of the cycle, though more systematic observational data are required for a definite confirmation. We discuss the role of both tracers in the context of the solar dynamo theory.Comment: 14 pages, 6 figure

\Lambda-buildings and base change functors

We prove an analog of the base change functor of \Lambda-trees in the setting of generalized affine buildings. The proof is mainly based on local and global combinatorics of the associated spherical buildings. As an application we obtain that the class of generalized affine building is closed under ultracones and asymptotic cones. Other applications involve a complex of groups decompositions and fixed point theorems for certain classes of generalized affine buildings.Comment: revised version, 29 pages, to appear in Geom. Dedicat

IGHV3-21 gene expression in patients with b-cell chronic lymphocytic leukemia in Ukraine

The aim of the study was to evaluate the frequency of IGHV3-21 gene usage and its clinical significance for patients with B-cell chronic lymphocytic leukemia (CLL) in Ukraine. Patients and Methods: Immunoglobulin variable heavy chain (IGHV) gene repertoire was studied in 189 CLL patients using reverse transcribed polymerase chain reaction and direct sequence of amplified products. Results: IGHV3-21 gene expression was found in 11 cases (5.8%), and its frequency was intermediate between Scandinavian (11.7%) and Mediterranean CLL (2.9%) cohorts. The most of cases (9 of 11) belonged to subset with heterogeneous HCDR3 (heteroHCDR3 subset), and only 2 cases – to subset with classical short ARDANGMDV motif (homHCDR3 subset). Six IGHV3-21 cases were mutated and 5 cases were unmutated. All unmutated cases (all were from heteroHCDR3 subset) had similarity of their HCDR3s with previously published sequences. The differences in overall (OS), progression-free (PFS) and treatment-free survival (TFS) for IGHV3-21 positive patients in comparison with CLL patients expressing the other IGHV genes were statistically insignificant. These survival parameters were comparable also for CLL patients with mutated IGHV3-21 gene usage and expression the others mutated IGHV genes. But remarkable feature of IGHV3-21 expressing patients was high incidence of solid tumors. They have developed in 4 IGHV3-21 positive cases (36.4%) and in 10 cases with expression of the others IGHV genes (5.6%, p = 0.0002). Furthermore, in small group of 6 patients with mutated IGHV3-21 gene expression, 3 patients had solid tumors and one underwent Richter transformation. Unmutated IGHV3-21 gene expressed patients had worse OS and PFS in comparison with CLL patients that expressed the others unmutated IGHV genes. Conclusion: Presented data are in agrement with the opinion about negative prognostic significance of IGHV3-21 gene expression regardless its mutation status. IGHV3-21 expression was associated with development of secondary solid tumors. Revealed high level of homology in heteroHDR3s subset might suggest about possible antigenic influence also, in addition to homHCDR3 subset that was proposed earlier.Цель: оценить частоту использования гена IGHV3-21 и его клиническое значение для больных B-клеточным хроническим лимфолейкозом (ХЛЛ) в Украине. Больные и методы исследования: репертуар генов вариабельных участков тяжелых цепей иммуноглобулинов (IGHV) изучали у 189 больных с ХЛЛ с помощью полимеразной цепной реакции на базе обратной транскрипции и прямого сиквенса амплифицированных продуктов. Результаты: экспрессия гена IGHV3-21 выявлена у 11 пациентов (5,8%), что занимает промежуточное положение между Скандинавской (11,7%) и Средиземноморской (2,9%) когортами. Большинство случаев (9 из 11) относились к подгруппе с гетерогенным третьим комплементарнымрегионом (heteroHCDR3 подгуппа) и только 2 случая — к подгруппе с коротким классическим ARDANGMDV мотивом (homHCDR уппа). есть IGHV3-21-позитивных случаев были мутированными и 5 — немутированными. Все немутированные случаи (все из heteroHCDR уппы) имели сходство HCDR3 с анее описанными последовательностями. Различия в общей выживаемости (OS), длительности периода до прогрессии заболевания (PFS) и начала лечения (TFS) для IGHV3-21-позитивных больных были статистически незначимы по сравнению с пациентами с ХЛЛ с экспрессией других IGHV-генов. Указанные параметры также сравнивали между больными ХЛЛ с экспрессией мутированных IGHV3-21- и других IGHV-генов. Отличительной чертой пациентов с экспрессией IGHV3-гена была высокая встречаемость солидных опухолей. Они развились в 4 IGHV3-21-позитивных случаях (36,4%) и в 10 случаях с экспрессией других IGHV-генов (5,6%, p = 0,0002). Кроме того, в небольшой группе больных (6) с экспрессией мутированного IGHV3-21-гена у 3 возникли солидные опухоли и 1 пациента — синдром Рихтера. У больных с экспрессией немутированного IGHV3-21-гена определяли худшие показатели OS и PFS по савнению с пациентами с экспрессией других немутированных IGHV-генов. Выводы: представленные данные согласуются с мнением о самостоятельном негативном прогностическом значении для больных с ХЛЛ экспрессии IGHV3-21-гена вне зависимости от его мутационного статуса. IGHV3-21-экспрессия была ассоциирована с развитием вторичных солидных опухолей. Выявленный высокий уровень гомологии в heteroHDR3s-подгруппе может свидетельствовать о возможном антигенном влиянии в дополнение к антигенному влиянию в homHCDR уппе, что было установлено ране

Magnetic Helicity Evolution During the Solar Activity Cycle: Observations and Dynamo Theory

We study a simple model for the solar dynamo in the framework of the Parker migratory dynamo, with a nonlinear dynamo saturation mechanism based on magnetic helicity conservation arguments. We find a parameter range in which the model demonstrates a cyclic behaviour with properties similar to that of Parker dynamo with the simplest form of algebraic alpha-quenching. We compare the nonlinear current helicity evolution in this model with data for the current helicity evolution obtained during 10 years of observations at the Huairou Solar Station of China. On one hand, our simulated data demonstrate behaviour comparable with the observed phenomenology, provided that a suitable set of governing dynamo parameters is chosen. On the other hand, the observational data are shown to be rich enough to reject some other sets of governing parameters. We conclude that, in spite of the very preliminary state of the observations and the crude nature of the model, the idea of using observational data to constrain our ideas concerning magnetic field generation in the framework of the solar dynamo appears promising.Comment: 10 pages, 3 Postscript figures, uses aa.cl

Turbulence in the Solar Atmosphere: Manifestations and Diagnostics via Solar Image Processing

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions.Comment: 26 pages, 7 figure

Distinction of representations via Bruhat-Tits buildings of p-adic groups

Introductory and pedagogical treatmeant of the article : P. Broussous "Distinction of the Steinberg representation", with an appendix by Fran\c{c}ois Court\`es, IMRN 2014, no 11, 3140-3157. To appear in Proceedings of Chaire Jean Morlet, Dipendra Prasad, Volker Heiermann Ed. 2017. Contains modified and simplified proofs of loc. cit. This article is written in memory of Fran\c{c}ois Court\`es who passed away in september 2016.Comment: 33 pages, 4 figure

Analysis of cancellation in two-dimensional magnetohydrodynamic turbulence

A signed measure analysis of two-dimensional intermittent magnetohydrodynamic turbulence is presented. This kind of analysis is performed to characterize the scaling behavior of the sign-oscillating flow structures, and their geometrical properties. In particular, it is observed that cancellations between positive and negative contributions of the field inside structures, are inhibited for scales smaller than the Taylor microscale, and stop near the dissipative scale. Moreover, from a simple geometrical argument, the relationship between the cancellation exponent and the typical fractal dimension of the structures in the flow is obtained.Comment: 21 pages, 5 figures (3 .jpg not included in the latex file