Zipf's law in Multifragmentation

We discuss the meaning of Zipf's law in nuclear multifragmentation. We remark that Zipf's law is a consequence of a power law fragment size distribution with exponent $\tau \simeq 2$. We also recall why the presence of such distribution is not a reliable signal of a liquid-gas phase transition

Quantum-field dynamics of expanding and contracting Bose-Einstein condensates

We analyze the dynamics of quantum statistics in a harmonically trapped Bose-Einstein condensate, whose two-body interaction strength is controlled via a Feshbach resonance. From an initially non-interacting coherent state, the quantum field undergoes Kerr squeezing, which can be qualitatively described with a single mode model. To render the effect experimentally accessible, we propose a homodyne scheme, based on two hyperfine components, which converts the quadrature squeezing into number squeezing. The scheme is numerically demonstrated using a two-component Hartree-Fock-Bogoliubov formalism.Comment: 9 pages, 4 figure

Cannabinoid receptors expression in bone marrow trephine biopsy of chronic lymphocytic leukaemia patients treated with purine analogues

Background: Cannabinoid receptors CB1 and CB2 are part the endocannabinoid system that plays an important role in the process of proliferation and apoptosis of different neoplastic cells. B-cell chronic lymphocytic leukaemia is one of the diseases in which these processes are altered. Aim: The aim of our study was the assessment of cannabinoid receptor expression on the B-lymphocytes in bone marrow trephine biopsy from leukaemic patients at diagnosis and after purine analogue treatment. Methods: The biopsy was taken routinely and standard immunohistochemical staining procedure for paraffin embedded sections was applied. The cannabinoid receptors were detected using specific primary polyclonal antibody anti-CB1 and anti-CB2. Additionally, an existence of cannabinoid receptors was confirmed by flow cytometry. Results: The results showed that the expression of CB1 receptor on the surface of neoplastic cells was lower than that of CB2 (17.0 ± 3.1% and 92.1 ± 1.7% respectively, p < 0.001). Nine of the patients responded to applied treatment with a reduction in leukaemic infiltration (77.2 ± 6.9% to 30.2 ± 6.5%, p = 0.007) and CB1 receptor expression (24.4 ± 4.8% to 8.6 ± 2.9%, p = 0.01), but there was no change in CB2 expression (91.7 ± 2.7% vs 90.9 ± 2.8%, p = 0.69). Four patients without remission expressed even greater number of the receptors. In all of the cases both cannabinoid receptor types antibodies gave positive reaction. Furthermore, the existence of cannabinoid receptors on neoplastic lymphocytes was confirmed by flow cytometry. Conclusion: The study provides original evidence for the existence of cannabinoid receptors on B-lymphocytes in chronic lymphocytic leukaemia patients. The receptors are thought to be a new structure that can modify the course of the disease and may be considered as a new target in leukaemia treatment.Обоснование: рецепторы каннабиноидов CB1 и CB2 яв ляются частью системы эндоканнабиноидов, которая играет важную роль в процессах пролиферации и апоптоза различных неопластических клеток. Одним из заболеваний, при которых происходит нарушение этих процессов, является В-клеточный хронический лимфлейкоз. Цель: оценка экспрессии рецепторов каннабиноидов на В-лимфоцитах в трепанобиоптатах у больных лейкозом до и после проведения лечения с использованием пуриновых аналогов. Методы: биоптаты получили рутинными методами; иммуногистохимическое исследование депарафинизированных срезов проводили по стандартной процедуре. Рецепторы каннабиноидов определяли с использованием специфических моноклональных антител анти-CB1 и анти-CB2. Кроме того, наличие рецепторов подтверждено при по- мощи проточной цитофлуориметрии. Результаты: показано, что экспрессия рецептора CB1 на поверхности опухолевых клеток ниже, чем экспрессия CB2 (17,0  ± 3,1% и 92,1 1,7% твенно, p < 0,001). После проведенного лечения у 9 пациентов отмечалось уменьшение лейкозного инфильтрата (77,2 6,9% до 30,2 6,5%, p = 0,007) и снижение экспрессии рецептора CB1 (24,4 4,8% до 8,6 2,9%, p = 0,01), однако различий в экспрессии CB2 не отмечали (91,7 2,7% против 90,9 2,8%, p = 0,69). У 4 пациентов, у которых не удалось достичь ремиссии, определяли даже повышение экспрессии рецепторов. Во всех случаях маркировки антителами к обоим типам рецепторов каннабиноидов отмечали поло- жительную реакцию. Более того, присутствие рецепторов каннабиноидов на злокачественных клетках подтверждали при помощи проточной цитометрии. Выводы: в ходе исследования показано изначальное наличие рецепторов каннабиноидов на В-лимфоцитах у больных хроническим лимфолейкозом. Указанные рецепторы могут быть новой структурой, которая может быть модифицирована в течение болезни, и могут считаться новой мишенью при лечении больных лейкозом

Human bone marrow mesenchymal stem cell-derived extracellular vesicles attenuate neuroinflammation evoked by focal brain injury in rats

Background Ischemic stroke is the major cause of long-term severe disability and death in aged population. Cell death in the infarcted region of the brain induces immune reaction leading to further progression of tissue damage. Immunomodulatory function of mesenchymal stem cells (MSCs) has been shown in multiple preclinical studies; however, it has not been successfully translated to a routine clinical practice due to logistical, economical, regulatory, and intellectual property obstacles. It has been recently demonstrated that therapeutic effect of intravenously administered MSCs can be recapitulated by extracellular vesicles (EVs) derived from them. However, in contrast to MSCs, EVs were not capable to decrease stroke-induced neuroinflammation. Therefore, the aim of the study was to investigate if intra-arterial delivery of MSC-derived EVs will have stronger impact on focal brain injury-induced neuroinflammation, which mimics ischemic stroke, and how it compares to MSCs. Methods The studies were performed in adult male Wistar rats with focal brain injury induced by injection of 1 mu l of 50 nmol ouabain into the right hemisphere. Two days after brain insult, 5 x 10(5) human bone marrow MSCs (hBM-MSCs) labeled with Molday ION or 1.3 x 10(9) EVs stained with PKH26 were intra-arterially injected into the right hemisphere under real-time MRI guidance. At days 1, 3, and 7 post-transplantation, the rats were decapitated, the brains were removed, and the presence of donor cells or EVs was analyzed. The cellular immune response in host brain was evaluated immunohistochemically, and humoral factors were measured by multiplex immunoassay. Results hBM-MSCs and EVs transplanted intra-arterially were observed in the rat ipsilateral hemisphere, near the ischemic region. Immunohistochemical analysis of brain tissue showed that injection of hBM-MSCs or EVs leads to the decrease of cell activation by ischemic injury, i.e., astrocytes, microglia, and infiltrating leucocytes, including T cytotoxic cells. Furthermore, we observed significant decrease of pro-inflammatory cytokines and chemokines after hBM-MSC or EV infusion comparing with non-treated rats with focal brain injury. Conclusions Intra-arterially injected EVs attenuated neuroinflammation evoked by focal brain injury, which mimics ischemic stroke, and this effect was comparable to intra-arterial hBM-MSC transplantation. Thus, intra-arterial injection of EVs might be an attractive therapeutic approach, which obviates MSC-related obstacles

A search on Dirac equation

The solutions, in terms of orthogonal polynomials, of Dirac equation with analytically solvable potentials are investigated within a novel formalism by transforming the relativistic equation into a Schrodinger like one. Earlier results are discussed in a unified framework and certain solutions of a large class of potentials are given.Comment: 9 page

Supersonic optical tunnels for Bose-Einstein condensates

We propose a method for the stabilisation of a stack of parallel vortex rings in a Bose-Einstein condensate. The method makes use of a hollow laser beam containing an optical vortex. Using realistic experimental parameters we demonstrate numerically that our method can stabilise up to 9 vortex rings. Furthermore we point out that the condensate flow through the tunnel formed by the core of the optical vortex can be made supersonic by inserting a laser-generated hump potential. We show that long-living immobile condensate solitons generated in the tunnel exhibit sonic horizons. Finally, we discuss prospects of using these solitons for analogue gravity experiments.Comment: 14 pages, 3 figures, published versio

Assessment of prognostic significance of cytoplasmic survivin expression in advanced oesophageal cancer.

Survivin is a member of the family of proteins, which inhibit apoptosis (inhibitor of apoptosis proteins - IAP). Expression of survivin was found in colorectal cancer, neuroblastoma, bladder cancer, non-small cell lung cancer, and breast cancer. There is some recent data indicating the correlation of poor prognosis and worse response to chemotherapy in patients with oesophageal squamous cell carcinoma (OSCC) expressing survivin. The aim of the present study was to assess survivin expression in cancerous tissue of patients with advanced OSCC and to test the potential correlation between survivin expression and clinicopathological data. Forty two patients (mean age 58.36+/-8.97 yrs), who were oesophagectomised due to squamous cell carcinoma of the thoracic oesophagus between 1998 and 2000, were retrospectively analysed. Cytoplasmic survivin expression, examined immunohistochemically, was found in 35 (83.33%) cases. No statistically significant correlation between survivin expression in the tumour and patients' gender, TNM stage, or vascular involvement was noted. The mean survival of patients with cytoplasmic survivin expression (17.81+/-5.51 months) was not statistically different to those with negative survivin staining (16+/-6.28 months) as assessed by Mantel-Cox test (p=0.49). Univariate regression analysis revealed UICC staging as the only predictor of survival in the analysed group (

Relativistic shape invariant potentials

Dirac equation for a charged spinor in electromagnetic field is written for special cases of spherically symmetric potentials. This facilitates the introduction of relativistic extensions of shape invariant potential classes. We obtain the relativistic spectra and spinor wavefunctions for all potentials in one of these classes. The nonrelativistic limit reproduces the usual Rosen-Morse I & II, Eckart, Poschl-Teller, and Scarf potentials.Comment: Corrigendum: The last statement above equation (1) is now corrected and replaced by two new statement

Nonparametric estimation of conditional transition probabilities in a non-Markov illness-death model

One important goal in multi-state modeling is the estimation of transition probabilities. In longitudinal medical studies these quantities are particularly of interest since they allow for long-term predictions of the process. In recent years signi ficant contributions have been made regarding this topic. However, most of the approaches assume independent censoring and do not account for the influence of covariates. The goal of the paper is to introduce feasible estimation methods for the transition probabilities in an illness-death model conditionally on current or past covariate measures. All approaches are evaluated through a simulation study, leading to a comparison of two di erent estimators. The proposed methods are illustrated using real a colon cancer data set.This research was nanced by FEDER Funds through Programa Operacional Factores de Competitividade COMPETE and by Portuguese Funds through FCT - Funda ção para a Cência e a Tecnologia, within Projects Est-C/MAT/UI0013/2011 and PTDC/MAT/104879/2008. We also acknowledge nancial support from the project Grants MTM2008-03129 and MTM2011-23204 (FEDER support included) of the Spanish Ministerio de Ciencia e Innovaci on and 10PXIB300068PR of the Xunta de Galicia. Partial support from a grant from the US National Security Agency (H98230-11-1-0168) is greatly appreciated

New Exactly Solvable Two-Dimensional Quantum Model Not Amenable to Separation of Variables

The supersymmetric intertwining relations with second order supercharges allow to investigate new two-dimensional model which is not amenable to standard separation of variables. The corresponding potential being the two-dimensional generalization of well known one-dimensional P\"oschl-Teller model is proven to be exactly solvable for arbitrary integer value of parameter $p:$ all its bound state energy eigenvalues are found analytically, and the algorithm for analytical calculation of all wave functions is given. The shape invariance of the model and its integrability are of essential importance to obtain these results.Comment: 23 page