Avalanches in complex spin networks

We investigate the magnetization reversal processes on classes of complex spin networks with antiferromagnetic interaction along the network links. With slow field ramping the hysteresis loop and avalanches of spin flips occur due to topological inhomogeneity of the network, even without any disorder of the magnetic interaction [B. Tadic, et al., Phys. Rev. Lett. 94 (2005) 137204]. Here we study in detail properties of the magnetization avalanches, hysteresis curves and density of domain walls and show how they can be related to the structural inhomogeneity of the network. The probability distribution of the avalanche size, N_s(s), displays the power-law behaviour for small s, i.e. N_s(s)\propto s^{-\alpha}. For the scale-free networks, grown with preferential attachment, \alpha increases with the connectivity parameter M from 1.38 for M=1 (trees) to 1.52 for M=25. For the exponential networks, \alpha is close to 1.0 in the whole range of M.Comment: 16 pages, 10 figures in 29 eps file

Are Devaney hairs fast escaping?

Beginning with Devaney, several authors have studied transcendental entire functions for which every point in the escaping set can be connected to infinity by a curve in the escaping set. Such curves are often called Devaney hairs. We show that, in many cases, every point in such a curve, apart from possibly a finite endpoint of the curve, belongs to the fast escaping set. We also give an example of a Devaney hair which lies in a logarithmic tract of a transcendental entire function and contains no fast escaping points.Comment: 22 pages, 1 figur

Escape rate and Hausdorff measure for entire functions

The escaping set of an entire function is the set of points that tend to infinity under iteration. We consider subsets of the escaping set defined in terms of escape rates and obtain upper and lower bounds for the Hausdorff measure of these sets with respect to certain gauge functions.Comment: 24 pages; some errors corrected, proof of Theorem 2 shortene

Impurity and strain effects on the magnetotransport of La1.85Sr0.15Cu(1-y)Zn(y)O4 films

The influence of zinc doping and strain related effects on the normal state transport properties(the resistivity, the Hall angle and the orbital magneto- resistance(OMR) is studied in a series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with values of y between 0 and 0.12 and various degrees of strain induced by the mismatch between the films and the substrate. The zinc doping affects only the constant term in the temperature dependence of cotangent theta but the strain affects both the slope and the constant term, while their ratio remains constant.OMR is decreased by zinc doping but is unaffected by strain. The ratio delta rho/(rho*tan^2 theta) is T-independent but decreases with impurity doping. These results put strong constraints on theories of the normal state of high- temperature superconductors

Magnetotransport in the Normal State of La1.85Sr0.15Cu(1-y)Zn(y)O4 Films

We have studied the magnetotransport properties in the normal state for a series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with values of y, between 0 and 0.12. A variable degree of compressive or tensile strain results from the lattice mismatch between the substrate and the film, and affects the transport properties differently from the influence of the zinc impurities. In particular, the orbital magnetoresistance (OMR) varies with y but is strain-independent. The relations for the resistivity and the Hall angle and the proportionality between the OMR and tan^2 theta are followed about 70 K. We have been able to separate the strain and impurity effects by rewriting the above relations, where each term is strain-independent and depends on y only. We also find that changes in the lattice constants give rise to closely the same fractional changes in other terms of the equation.The OMR is more strongly supressed by the addition of impurities than tan^2 theta. We conclude that the relaxation ratethat governs Hall effect is not the same as for the magnetoresistance. We also suggest a correspondence between the transport properties and the opening of the pseudogap at a temperature which changes when the La-sr ratio changes, but does not change with the addition of the zinc impurities

The Śnieżka peatland as a candidate for the Global Boundary Stratotype Section and Point for the Anthropocene series

The subalpine, atmospherically fed Śnieżka peatland, located in the Polish part of the Sudetes, is one of the nominated candidates for the GSSP of the Anthropocene. Data from two profiles, Sn1 (2012) and Sn0 (2020), from this site are critical for distinguishing the proposed epoch, while an additional core Sn2 is presented to support main evidence. The Sn0 archive contains a wide array of critical markers such as plutonium (Pu), radiocarbon (F14C), fly ash particles, Hg and stable C and N isotopes which are consistent with the previously well documented 210Pb/14C dated Sn1 profile, which provides a high-resolution and comprehensive database of trace elements and rare earth elements (REE), Pb isotopes, Pu, Cs, pollen and testate amoebae. The 1952 worldwide appearance of Pu, owing to its global synchronicity and repeatability between the cores, is proposed here as a primary marker of the Anthropocene, supported by the prominent upturn of selected chemostratigraphic and biostratigraphic indicators as well as the appearance of technofossils and artificial radionuclides

Coherent Potential Approximation for `d - wave' Superconductivity in Disordered Systems

A Coherent Potential Approximation is developed for s-wave and d-wave superconductivity in disordered systems. We show that the CPA formalism reproduces the standard pair-breaking formula, the self-consistent Born Approximation and the self-consistent T-matrix approximation in the appropriate limits. We implement the theory and compute T_c for s-wave and d-wave pairing using an attractive nearest neighbor Hubbard model featuring both binary alloy disorder and a uniform distribution of scattering site potentials. We determine the density of states and examine its consequences for low temperature heat capacity. We find that our results are in qualitative agreement with measurements on Zn doped YBCO superconductors.Comment: 35 pages, 23 figures, submitted to Phys Rev.

Is FLT3 internal tandem duplication an unfavorable risk factor for high risk children with acute myeloid leukemia? : Polish experience

According to the AML-BFM 2004 Interim, a treatment protocol used in Poland since 2005, presence of FLT3 internal tandem duplication (FLT3/ITD) qualifies a patient with acute myeloid leukemia (AML) to a high-risk group (HRG). The present study was aimed to identify the prevalence of FLT3/ITD in children with AML in Poland and to evaluate its prognostic significance in the HRG patients. Out of 291 children with de novo AML treated in 14 Polish centers between January 2006 and December 2012, samples from 174 patients were available for FLT3/ITD analysis. Among study patients 108 children (61.7%) were qualified to HRG. Genomic DNA samples from bone marrow were tested for identification of FLT3/ITD mutation by PCR amplification of exon 14 and 15 of FLT3 gene. Clinical features and treatment outcome in patients with and without FLT3/ITD were analyzed in the study. The FLT3/ITD was found in 14 (12.9%) of 108 HRG children. There were no significant differences between children with and without FLT3/ITD in age and FAB distribution. The white blood cells count in peripheral blood at diagnosis was significantly higher (p <0.01) in the children with FLT3/ITD. Over 5-year overall survival rate for FLT3/ITD positive children was worse (42.4%) comparing to FLT3/ITD negative children (58.9%), but the statistical difference was not significant. However, over 5-year survivals free from treatment failures were similar. The FLT3/ITD rate (12.9%) observed in the study corresponded to the published data. There was no significant impact of FLT3/ITD mutation on survival rates, although further studies are needed on this subject

Abscisic Acid Insensitive 4 transcription factor is an important player in the response of Arabidopsis thaliana to two-spotted spider mite (Tetranychus urticae) feeding.

Plants growing in constantly changeable environmental conditions are compelled to evolve regulatory mechanisms to cope with biotic and abiotic stresses. Effective defence to invaders is largely connected with phytohormone regulation, resulting in the production of numerous defensive proteins and specialized metabolites. In our work, we elucidated the role of the Abscisic Acid Insensitive 4 (ABI4) transcription factor in the plant response to the two-spotted spider mite (TSSM). This polyphagous mite is one of the most destructive herbivores, which sucks mesophyll cells of numerous crop and wild plants. Compared to the wild-type (Col-0) Arabidopsis thaliana plants, the abi4 mutant demonstrated increased susceptibility to TSSM, reflected as enhanced female fecundity and greater frequency of mite leaf damage after trypan blue staining. Because ABI4 is regarded as an important player in the plastid-to-nucleus retrograde signalling process, we investigated the plastid envelope membrane dynamics using stroma-associated fluorescent marker. Our results indicated a clear increase in the number of stroma-filled tubular structures deriving from the plastid membrane (stromules) in the close proximity of the site of mite leaf damage, highlighting the importance of chloroplast-derived signals in the response to TSSM feeding activity

Cross-talk between high light stress and plant defence to the two-spotted spider mite in Arabidopsis thaliana

Little is known about how plants deal with arthropod herbivores under the fluctuating light intensity and spectra which occur in natural environments. Moreover, the role of simultaneous stress such as excess light (EL) in the regulation of plant responses to herbivores is poorly characterized. In the current study, we focused on a mite-herbivore, specifically, the two-spotted spider mite (TSSM), which is one of the major agricultural pests worldwide. Our results showed that TSSM-induced leaf damage (visualized by trypan blue staining) and oviposition rate (measured as daily female fecundity) decreased after EL pre-treatment in wild-type Arabidopsis plants, but the observed responses were not wavelength specific. Thus, we established that EL pre-treatment reduced Arabidopsis susceptibility to TSSM infestation. Due to the fact that a portion of EL energy is dissipated by plants as heat in the mechanism known as non-photochemical quenching (NPQ) of chlorophyll fluorescence, we tested an Arabidopsis npq4-1 mutant impaired in NPQ. We showed that npq4-1 plants are significantly less susceptible to TSSM feeding activity, and this result was not dependent on light pre-treatment. Therefore, our findings strongly support the role of light in plant defence against TSSM, pointing to a key role for a photo-protective mechanism such as NPQ in this regulation. We hypothesize that plants impaired in NPQ are constantly primed to mite attack, as this seems to be a universal evolutionarily conserved mechanism for herbivores