Mesoscopic pinning forces in neutron star crusts

The crust of a neutron star is thought to be comprised of a lattice of nuclei immersed in a sea of free electrons and neutrons. As the neutrons are superfluid their angular momentum is carried by an array of quantized vortices. These vortices can pin to the nuclear lattice and prevent the neutron superfluid from spinning down, allowing it to store angular momentum which can then be released catastrophically, giving rise to a pulsar glitch. A crucial ingredient for this model is the maximum pinning force that the lattice can exert on the vortices, as this allows us to estimate the angular momentum that can be exchanged during a glitch. In this paper we perform, for the first time, a detailed and quantitative calculation of the pinning force \emph{per unit length} acting on a vortex immersed in the crust and resulting from the mesoscopic vortex-lattice interaction. We consider realistic vortex tensions, allow for displacement of the nuclei and average over all possible orientation of the crystal with respect to the vortex. We find that, as expected, the mesoscopic pinning force becomes weaker for longer vortices and is generally much smaller than previous estimates, based on vortices aligned with the crystal. Nevertheless the forces we obtain still have maximum values of order $f_{\rm{pin}}\approx 10^{15}$ dyn/cm, which would still allow for enough angular momentum to be stored in the crust to explain large Vela glitches, if part of the star is decoupled during the event.Comment: 17 pages, 16 figures, 5 table

Integrated Analysis of Myocardial Blush and ST-Segment Elevation Recovery After Successful Primary Angioplasty

Background — ST-segment elevation (ΣSTe) recovery and the angiographic myocardial blush (MB) grade are useful markers of microvascular reperfusion after recanalization of the infarct-related artery. We investigated the ability of a combined analysis of MB grade and ΣSTe changes to identify different patterns of myocardial reperfusion shortly after primary percutaneous coronary angioplasty (PTCA) and to predict 7-day and 6-month left ventricular (LV) functional recovery. Methods and Results — MB grade and ΣSTe recovery were evaluated shortly after successful primary PTCA (restoration of TIMI grade 3 flow) in 114 consecutive patients with ΣSTe acute myocardial infarction. LV function was assessed by 2D echocardiograms before PTCA and at 7 days and 6 months thereafter. By combining MB and ΣSTe changes, 3 main groups of patients were identified. Group 1 patients (n=60) had both significant MB (grade 2 to 3) and ΣSTe recovery (>50% versus basal ΣSTe) and a high rate of 7-day (65%) and 6-month (95%) LV functional recovery. In group 2 patients (n=21), who showed MB but persistent ΣSTe, the prevalence of early LV functional recovery was low (24%) but increased up to 86% in the late phase. Group 3 patients (n=28), who had neither significant MB nor ΣSTe resolution, had poor early (18%) and late (32%) LV functional recovery. Conclusions — After successful primary PTCA, integrated analysis of MB and ΣSTe recovery allows a real-time grading of microvascular reperfusion of the infarct area and predicts the time-course and magnitude of LV functional recovery

Geometry and Dynamics of a Coupled 4D-2D Quantum Field Theory

Geometric and dynamical aspects of a coupled 4D-2D interacting quantum field theory - the gauged nonAbelian vortex - are investigated. The fluctuations of the internal 2D nonAbelian vortex zeromodes excite the massless 4D Yang-Mills modes and in general give rise to divergent energies. This means that the well-known 2D CP(N-1) zeromodes associated with a nonAbelian vortex become nonnormalizable. Moreover, all sorts of global, topological 4D effects such as the nonAbelian Aharonov-Bohm effect come into play. These topological global features and the dynamical properties associated with the fluctuation of the 2D vortex moduli modes are intimately correlated, as shown concretely here in a U(1) x SU(N) x SU(N) model with scalar fields in a bifundamental representation of the two SU(N) factor gauge groups.Comment: Latex, 39 pages, 5 figure

Systematics and character evolution of capitate hydrozoans

Capitate hydrozoans are a morphologically and ecologically diverse hydrozoan suborder, currently including about 200 species. Being grouped in two clades, Corynida and Zancleida, these hydrozoans still show a number of taxonomic uncertainties at the species, genus and family levels. Many Capitata species established symbiotic relationships with other benthic organisms, including bryozoans, other cnidarians, molluscs and poriferans, as well as with planktonic dinoflagellates for mixotrophic relationships and with bacteria for thiotrophic ectosymbioses. Our study aimed at providing an updated and comprehensive phylogeny reconstruction of the suborder, at modelling the evolution of selected morphological and ecological characters, and at testing evolutionary relationships between the symbiotic lifestyle and the other characters, by integrating taxonomic, ecological and evolutionary data. The phylogenetic hypotheses here presented shed light on the evolutionary relationships within Capitata, with most families and genera being recovered as monophyletic. The genus Zanclea and family Zancleidae, however, were divided into four divergent clades, requiring the establishment of the new genus Apatizanclea and the new combinations for species in Zanclea and Halocoryne genera. The ancestral state reconstructions revealed that symbiosis arose multiple times in the evolutionary history of the Capitata, and that homoplasy is a common phenomenon in the group. Correlations were found between the evolution of symbiosis and morphological characters, such as the perisarc. Overall, our results highlighted that the use of genetic data and a complete knowledge of the life cycles are strongly needed to disentangle taxonomic and systematic issues in capitate hydrozoans. Finally, the colonization of tropical habitat appears to have influenced the evolution of a symbiotic lifestyle, playing important roles in the evolution of the group.</p

Host-derived circulating cells do not significantly contribute to cardiac regeneration in heterotopic rat heart transplants

OBJECTIVES: The aim of this study was to investigate the contribution of host-derived circulating cells to cardiac repair after tissue damage using the model of heterotopic heart transplantation between transgenic recipient rats expressing green fluorescent protein (GFP) and wild-type donors. METHODS: Unlabeled donor rat hearts, some of which underwent prolonged cold ischemia pretreatment, were transplanted into the abdominal cavity of GFP+ transgenic recipient rats and were analyzed 15 and 90 days after surgery. An additional experimental group underwent heart transplantation following administration of granulocyte-colony stimulatory factor (G-CSF) to mobilize bone marrow cells. RESULTS: Most transplants contained GFP+ mature cardiomyocytes. However, systematic counting in the transplants showed that the proportion of GFP+ cardiomyocytes was only 0.0005% to 0.008% of all cardiomyocytes. These relative proportions did not change after G-CSF treatment, despite evidence for sustained marrow cell mobilization. Confocal image analysis showed that the majority of GFP+ cardiomyocytes contained a high number of nuclei, suggesting that these cells may derive from fusion events. Very rarely, small GFP+ undifferentiated cells, expressing GATA-4, were also identified. Occasionally, GFP+ endothelial cells, but not smooth muscle cells, were detected in blood vessels of some transplants. CONCLUSIONS: Our results demonstrate that cardiomyocytes expressing a host transgenic marker are detectable in heterotopic heart transplants; however, they do not significantly contribute to repopulation of the damaged myocardium

Stem cell engraftment in a heterotopic cardiac hamster-to-rat xenotransplantation model

Introduction: The hamster-to-rat species combination is considered a concordant difficult xenotransplantation model that resembles the immunological situation observed when transplanting hDAF pig organs into non-human primates. The aim of the present study was to investigate in a hamster-to-rat cardiac model the capacity of progenitor stem cells to engraft the transplanted heart and transdifferentiate into cardiomyocytes. Material and methods: A heterotopic cardiac transplantation procedure was performed between Golden Syrian hamsters (Harlan Italia) which served as organ donors and green fluorescent protein (GFP) transgenic Sprague\u2013 Dawley rat (Japan SLC) recipients. Recipients underwent splenectomy during the transplantation procedure and were treated by intramuscular cyclosporine A (Novartis) at a dose of 15 mg/kg/day throughout the postoperative period. As a control, a group of GFP transgenic recipients underwent allogeneic heterotopic heart transplantation and immunosuppression by the administration of cyclosporine A. The transplanted hearts were harvested on postoperative day 15 and analyzed histologically for the presence of GFP positive cells. The GFP positive cells were characterized for specific muscle differentiation markers and analyzed by immunofluoresence and confocal microscopy. Results: A high number of GFP positive cells were found in the xenotransplanted hamster hearts, however the majority were inflammatory in nature. In four out of six (67%) cases analyzed, a limited number of GFP positive cardiac cells with shape and morphology compatible with that of mature cardiomyocytes were found. It is noteworthy that these cells expressed cardiomyocyte-specific markers such as desmin and myosin heavy chain. In the allotransplanted group similar GFP positive cardiac cells were observed in 10 out of 12 (83%) cases. Conclusions: The heterotopic cardiac hamster-to-rat xenotransplantation model is an appropriate animal model to study stem cell engraftment in damaged hearts after a transplant procedure between different species. Our preliminary data also suggest that also a xenogeneic environment may provide adequate mediators and cell signals to allow donor stem cell engraftment and differentiation into cardiomyocytes. Fusion vs. transdifferentiation events are currently under examination

IgE-Mediated Immune Response and Antibody-Mediated Rejection

Active antibody-mediated rejection is the main cause of kidney transplant loss, sharing with SLE the alloimmune response and the systemic activation of the IFN-α&nbsp;pathway. IgE-mediated immune response plays a key role in the development of SLE nephritis and is associated with IFN-α secretion. The aim of our study was to investigate IgE-mediated immune response in antibody-mediated rejection