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By means of89Y nuclear magnetic resonance (NMR) spectra direct evidence of staggered magnetization induced by a uniform field has been obtained in the Heisenberg antiferromagnetic S = 1 chain Y2BaNi1−xMgxO5. A correspondence between the resonance lines and the lattice positions is established, providing an image of the alternating magnetic moments that develop around the Mg impurities at the chain boundaries. The amplitude of these moments is found to decrease exponentially from the edges, with a characteristic decay distance equal to the magnetic correlation length numerically evaluated for an infinite chain. While the magnetization pertaining to ions far from the boundaries behaves as in typical gapped systems, the edge spins exhibit an S = 1/2 Curie-like deviation. These results promote the NMR approach to access the spin-spin correlation function in antiferro-magnetic quantum spin systems at finite temperatures. [ABSTRACT FROM AUTHOR]

The nature of level set percolation in the two-dimensional Gaussian free field has been an elusive question. Using a loop-model mapping, we show that there is a nontrivial percolation transition and characterize the critical point. In particular, the correlation length diverges exponentially, and the critical clusters are "logarithmic fractals," whose area scales with the linear size as A∼L^{2}/sqrt[lnL]. The two-point connectivity also decays as the log of the distance. We corroborate our theory by numerical simulations. Possible conformal field theory interpretations are discussed.

We study transitions in log-correlated random energy models (logREMs) that are related to the violation of a Seiberg bound in Liouville field theory (LFT): the binding transition and the termination point transition (a.k.a., pre-freezing). By means of LFT-logREM mapping, replica symmetry breaking and traveling-wave equation techniques, we unify both transitions in a two-parameter diagram, which describes the free-energy large deviations of logREMs with a deterministic background log potential, or equivalently, the joint moments of the free energy and Gibbs measure in logREMs without background potential. Under the LFT-logREM mapping, the transitions correspond to the competition of discrete and continuous terms in a four-point correlation function. Our results provide a statistical interpretation of a peculiar nonlocality of the operator product expansion in LFT. The results are rederived by a traveling-wave equation calculation, which shows that the features of LFT responsible for the transitions are reproduced in a simple model of diffusion with absorption. We examine also the problem by a replica symmetry breaking analysis. It complements the previous methods and reveals a rich large deviation structure of the free energy of logREMs with a deterministic background log potential. Many results are verified in the integrable circular logREM, by a replica-Coulomb gas integral approach. The related problem of common length (overlap) distribution is also considered. We provide a traveling-wave equation derivation of the LFT predictions announced in a precedent work.

Lenalidomide is a therapeutically effective drug in chronic lymphocytic leukemia (CLL). Twenty-seven CLL patients were treated with lenalidomide in a phase II clinical trial. Ten patients were grouped as responders (R) and 6 as nonresponders (NR). We evaluated T lymphocytes, NK, monocytes and dendritic cells at baseline and after treatment. A gene expression analysis was performed on 16 CLL samples collected before treatment. The levels of immune cells or immune-related cytokines are not different between R and NR patients. However, CLL patients sensitive to lenalidomide clearly show a peculiar gene expression profile in leukemic cells. The most up-regulated gene (fold change =  +23 in R vs. NR) is Wnt inhibitor SHISA homolog 3 (SHISA3). SHISA3 high CLL are characterized by a restrained activation of Wnt signaling and sensibility to lenalidomide-induced apoptosis. In conclusion, SHISA3 is a candidate gene for the identification of CLL patients who will benefit of lenalidomide treatment as single agent.

An exact mapping is established between the c≥25 Liouville field theory (LFT) and the Gibbs measure statistics of a thermal particle in a 2D Gaussian free field plus a logarithmic confining potential. The probability distribution of the position of the minimum of the energy landscape is obtained exactly by combining the conformal bootstrap and one-step replica symmetry-breaking methods. Operator product expansions in the LFT allow us to unveil novel universal behaviors of the log-correlated random energy class. High-precision numerical tests are given.

Lenalidomide is an IMID immunomodulatory agent clinically active in patients with chronic lymphocytic leukemia (CLL). We evaluated the activity of lenalidomide inside an in vitro coculture system of endothelial and CLL cells. Lenalidomide was able to inhibit CLL survival advantage mediated by endothelial contact. Moreover, the marked increase of in vitro angiogenesis determined by CLL-derived conditioned media was reduced by lenalidomide. We also analyzed peripheral blood collected from 27 patients with relapsed or refractory CLL being treated with lenalidomide within a phase II trial. Plasma levels of VEGF and THBS-1 decreased, whereas Ang2 and Ang increased during treatment. Patients who respond to lenalidomide showed a more pronounced decrease of VEGF and bFGF than did patients with stable or progressive disease (p = 0.007 and p = 0.005). Furthermore, lenalidomide reduced circulating endothelial cells and endothelial progenitors by increasing the percentage of apoptotic cells. Conversely, for six matched bone marrow biopsies available before and after treatment, we did not detect any modification in vessel density, suggesting a possible mechanism of vessel normalization rather than regression. In conclusion, our study provides further evidence that the anti-CLL effect of lenalidomide is mediated through the alteration of microenvironmental elements, implying the modulation of several angiogenesis-related factors and disruption of CLL crosstalk with endothelial cells., (Copyright © 2014 ISEH - Society for Hematology and Stem Cells. Published by Elsevier Inc. All rights reserved.)

We report on the numerical measures on different spin interfaces and Fortuin-Kasteleyn (FK) cluster boundaries in the Askhin-Teller (AT) model. For a general point on the AT critical line, we find that the fractal dimension of a generic spin cluster interface can take one of four different possible values. In particular we found spin interfaces whose fractal dimension is d(f)=3/2 all along the critical line. Furthermore, the fractal dimension of the boundaries of FK clusters was found to satisfy all along the AT critical line a duality relation with the fractal dimension of their outer boundaries. This result provides clear numerical evidence that such duality, which is well known in the case of the O(n) model, exists in an extended conformal field theory.

The clinical relevance of angiopoietin-2 (Ang2) in chronic lymphocytic leukemia (CLL) was previously suggested by the association between high Ang2, and shorter progression-free survival reported in small series of patients. Here, we evaluated Ang2 glycoprotein levels in plasma samples collected from a multicentric cohort of CLL patients (n = 316) using an enzyme-linked immunosorbent assay method, and we investigated its prognostic role in relation to time to first treatment (TTFT) and overall survival. Based on a cutoff equal to 2459 pg/mL, we divided our cohort in 2 subsets (high and low Ang2) composing 100 (31.6%) and 216 (68.4%) patients, respectively. High Ang2 was predictive of reduced TTFT (P < .001) and overall survival (P = .002). Multivariate analysis confirmed that high Ang2 was an independent prognosticator for TTFT (hazard ratio = 1.739; 95% confidence interval, 1.059-2.857; P = .029). Significant associations were found between high Ang2 and advanced Binet stages (P < .001), high beta(2)-microglobulin (P < .001), unmutated variable region of immunoglobulin heavy chain gene status (P < .001), high CD38 and zeta-chain-associated protein kinase 70 expression (P < .001 and P = .003), and intermediate/high cytogenetic risk (P = .005). Moreover, Ang2 added prognostic power to other conventional prognosticators and helped to refine prognosis among CLL subsets with both high and low vascular endothelial growth factor plasma levels. Ang2 plasma level may be a useful independent prognosticator for CLL.

Emerging evidence suggests that angiogenic signalling pathways play important role in the patho-biology of chronic lymphocytic leukemia (CLL). Our goal was to investigate: (i) the spontaneous and hypoxia-induced production of pro-angiogenic factors, VEGF and Ang2, by Real-time PCR and ELISA, (ii) the degree of vascularization in CLL-infiltrated bone marrow (BM) compartment by CD34 immunohistochemical staining of microvessels and (iii) the direct angiogenic effect of CLL-derived VEGF and Ang2 by function-blocking experiments in Matrigel assays. The results demonstrated that CLL cells spontaneously express both VEGF and Ang2 and are able to secrete these factors in surrounding microenvironment. Full-length Ang2 mRNA and truncated form Ang2(443) were detectable. Moreover, CLL cells were shown to enhance secretion of both VEGF and Ang2 proteins when subjected to hypoxic condition. Furthermore, increased in vivo and in vitro angiogenesis was induced by CLL cells. Enhanced BM vascularity correlated with Ig-unmutated CLL subset and increased expression of Ang2. Then, we demonstrated that supernatants obtained from CLL cells significantly increase the HUVEC tube formation in Matrigel assays and that this enhanced angiogenic capacity is mediated by both CLL-derived VEGF and Ang2. Taken together, these results suggest that several simultaneous mechanisms may be involved in the CLL capacity to induce the disruption of pre-existing vessel structures to give rise to tumor neoangiogenesis. The preliminary studies in solid tumors, showing that the disruption of Ang2 function can inhibit tumor vessel density and growth, are encouraging and suggest the possibility of new future therapeutic options targeting CLL microenvironment., (Copyright (c) 2009 Elsevier Ltd. All rights reserved.)

We study geometrical properties of interfaces in the random-temperature q-states Potts model as an example of a conformal field theory weakly perturbed by quenched disorder. Using conformal perturbation theory in q-2 we compute the fractal dimension of Fortuin-Kasteleyn (FK) domain walls. We also compute it numerically both via the Wolff cluster algorithm for q=3 and via transfer-matrix evaluations. We also obtain numerical results for the fractal dimension of spin clusters interfaces for q=3. These are found numerically consistent with the duality kappaspinkappaFK=16 as expressed in putative SLE parameters.

We measured the angiopoietin-2 (Ang-2) expression in early chronic lymphocytic leukemia (CLL) patients, pointing our attention on the association with immunoglobulin (IgV(H)) mutational status, CD38 expression and clinical outcome. Our results indicate that Ang-2 expression is heterogeneous among Binet stage A CLL patients. CLL patients can be divided into two subgroups (Ang-2 positive and Ang-2 negative CLL) with 30% of them displaying Ang-2 RNA levels above the cut off. A shorter progression-free survival was observed in Ang-2 positive CLL subset (p=0.032). Abnormal Ang-2 expression was also associated with unmutated IgV(H) genes (p<0.0001) and increased bone marrow angiogenesis (p=0.028), suggesting a role of Ang-2 in disease-progression of early CLL patients.

The Schramm-Loewner evolution (SLE) is a powerful tool to describe fractal interfaces in 2D critical statistical systems, yet the application of SLE is well established for statistical systems described by quantum field theories satisfying only conformal invariance, the so-called minimal conformal field theories (CFTs). We consider interfaces in Z(N) spin models at their self-dual critical point for N = 4 and N = 5. These lattice models are described in the continuum limit by nonminimal CFTs where the role of a ZN symmetry, in addition to the conformal one, should be taken into account. We provide numerical results on the fractal dimension of the interfaces which are SLE candidates for nonminimal CFTs. Our results are in excellent agreement with some recent theoretical predictions.