The role of E1-E2 interplay in multiphonon Coulomb excitation

In this work we study the problem of a charged particle, bound in a harmonic-oscillator potential, being excited by the Coulomb field from a fast charged projectile. Based on a classical solution to the problem and using the squeezed-state formalism we are able to treat exactly both dipole and quadrupole Coulomb field components. Addressing various transition amplitudes and processes of multiphonon excitation we study different aspects resulting from the interplay between E1 and E2 fields, ranging from classical dynamic polarization effects to questions of quantum interference. We compare exact calculations with approximate methods. Results of this work and the formalism we present can be useful in studies of nuclear reaction physics and in atomic stopping theory.Comment: 10 pages, 6 figure

B-cell Zone Reticular Cell Microenvironments Shape CXCL13 Gradient Formation

Through the formation of concentration gradients, morphogens drive graded responses to extracellular signals, thereby fine-tuning cell behaviors in complex tissues. Here we show that the chemokine CXCL13 forms both soluble and immobilized gradients. Specifically, CXCL13+ follicular reticular cells form a small-world network of guidance structures, with computer simulations and optimization analysis predicting that immobilized gradients created by this network promote B-cell trafficking. Consistent with this prediction, imaging analysis show that CXCL13 binds to extracellular matrix components in situ, constraining its diffusion. CXCL13 solubilization requires the protease cathepsin B that cleaves CXCL13 into a stable product. Mice lacking cathepsin B display aberrant follicular architecture, a phenotype associated with effective B cell homing to but not within lymph nodes. Our data thus suggest that reticular cells of the B cell zone generate microenvironments that shape both immobilized and soluble CXCL13 gradient

Up-regulation of IGF-1 in the frontal cortex of piglets exposed to an environmentally enriched arena

Environmental enrichment (EE) is widely used in the life sciences to study effects of environment on the brain. In pigs, despite lack of EE being a key welfare issue there is little understanding of brain effects of EE in pigs. This project aimed to study the effects of exposure to an EE arena on piglet behaviours and on brain gene expression levels with a focus on IGF-1 and related genes. Eight litters of large white × landrace × Hampshire piglets were farrowed and raised in a free farrowing system (PigSAFE). At 42 days of age, 6 piglets per litter were given access to an enriched arena with plentiful peat, straw and space, (in groups of 4 made up of stable pairs) for 15 min per day on 5 consecutive days to allow them to habituate to the apparatus. Piglet behaviours were recorded in the arena for 15 min periods on 3 consecutive days. On the final day only one pair of test piglets per litter was given access to the arena. Brain tissue was collected within 45 min of the test from piglets exposed to the arena on the day and their non-exposed littermate controls. RNA was extracted from the frontal cortex and QRT-PCR for selected genes run on a Stratgene MX3005P. In both the home pen and the EE arena litters spent the largest proportion of time engaging in foraging behaviour which was significantly increased in the enriched arena (t(7) = 5.35, df = 6, p = 0.001). There were decreases in non-running play (t(7) = 4.82, p = 0.002) and inactivity (t(7) = 4.6, p = 0.002) in the arena. A significant fold change increase (FC = 1.07, t = 4.42, p = 0.002) was observed in IGF-1 gene expression in the frontal cortex of piglets exposed to the enriched arena compared to those not exposed on the day of culling. No change in expression was observed in CSF1, the IGF-1 receptor gene nor in any of the binding proteins tested (IGFBP1-6). There was a weak tendency for increased expression of the neurotrophic factor BDNF1 (fold change: 1.03; t(7) = 1.54, p = 0.1). We believe this work is the first to explore effects of EE on pig brain physiology and development, and also points to a potential role for IGF-1 in brain effects of EE

Clinical characteristics of patients with lymphoproliferative neoplasms in the setting of systemic autoimmune diseases

Clinical features of 40 lymphoproliferative neoplasm patients in the setting of systemic autoimmune diseases managed in the Clinic of Hematology during 1994-2006 were analyzed retrospectively. The classification of systemic autoimmune disease patients was as follows: 15 systemic lupus erythematosus-SLE, 11 rheumatoid arthritis-RA, 12 Sjögren's syndrome-SS, 1 scleroderma, and 1 dermatomyositis. Patients comprised 31 women and 9 men of mean age 55 years (range 33-76). Systemic autoimmune diseases preceeded the development of lymphoproliferative neoplasms in 37/40 (92.5%) patients. Mean latency period between the onset of systemic autoimmune diseases and lymphoproliferative neoplasms occurrence was significantly longer in RA (113 months) than in SLE (75 months) and SS patients (65 months)-P 0.05. Our findings are in line with earlier reports showing a high proportion of patients with advanced disease, constitutional symptoms, extranodal manifestations, high grade histology, and low OS in the systemic autoimmune diseases setting. Copyright © Springer Science+Business Media, LLC 2011