10,843 research outputs found

    White Dwarfs In Ngc6397 And M4: Constraints On The Physics Of Crystallization

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    We explore the physics of crystallization in the dense Coulomb plasma of the deep interiors of white dwarf stars using the color-magnitude diagram and luminosity function constructed from Hubble Space Telescope photometry of the globular cluster M 4 and compare it with our results for proper motion cleaned Hubble Space Telescope photometry of the globular cluster NGC 6397. We demonstrate that the data are consistent with a binary mixture of carbon and oxygen crystallizing at a value of Gamma higher than the theoretical value for a One Component Plasma (OCP). We show that this result is in line with the latest Molecular Dynamics simulations for binary mixtures of C/O. We discuss implications for future work.Astronom

    Long-distance entanglement and quantum teleportation in XX spin chains

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    Isotropic XX models of one-dimensional spin-1/2 chains are investigated with the aim to elucidate the formal structure and the physical properties that allow these systems to act as channels for long-distance, high-fidelity quantum teleportation. We introduce two types of models: I) open, dimerized XX chains, and II) open XX chains with small end bonds. For both models we obtain the exact expressions for the end-to-end correlations and the scaling of the energy gap with the length of the chain. We determine the end-to-end concurrence and show that model I) supports true long-distance entanglement at zero temperature, while model II) supports {\it ``quasi long-distance''} entanglement that slowly falls off with the size of the chain. Due to the different scalings of the gaps, respectively exponential for model I) and algebraic in model II), we demonstrate that the latter allows for efficient qubit teleportation with high fidelity in sufficiently long chains even at moderately low temperatures.Comment: 9 pages, 6 figure

    Phenomenology Tools on Cloud Infrastructures using OpenStack

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    We present a new environment for computations in particle physics phenomenology employing recent developments in cloud computing. On this environment users can create and manage "virtual" machines on which the phenomenology codes/tools can be deployed easily in an automated way. We analyze the performance of this environment based on "virtual" machines versus the utilization of "real" physical hardware. In this way we provide a qualitative result for the influence of the host operating system on the performance of a representative set of applications for phenomenology calculations.Comment: 25 pages, 12 figures; information on memory usage included, as well as minor modifications. Version to appear in EPJ

    Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

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    In this work, the capability of primary, monocyte-derived dendritic cells (DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a strategy to induce selective cell death in these MNP-loaded DCs using external alternating magnetic fields (AMFs) is reported. No significant decrease in the cell viability of MNP-loaded DCs, compared to the control samples, was observed after five days of culture. The amount of MNPs incorporated into the cytoplasm was measured by magnetometry, which confirmed that 1 to 5 pg of the particles were uploaded per cell. The intracellular distribution of these MNPs, assessed by transmission electron microscopy, was found to be primarily inside the endosomic structures. These cells were then subjected to an AMF for 30 min, and the viability of the blank DCs (i.e., without MNPs), which were used as control samples, remained essentially unaffected. However, a remarkable decrease of viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was observed after the same 30 min exposure to an AMF. The same results were obtained using MNPs having either positive (NH2+) or negative (COOH-) surface functional groups. In spite of the massive cell death induced by application of AMF to MNP-loaded DCs, the amount of incorporated magnetic particles did not raise the temperature of the cell culture. Clear morphological changes at the cell structure after magnetic field application were observed using scanning electron microscopy. Therefore, local damage produced by the MNPs could be the main mechanism for the selective cell death of MNP-loaded DCs under an AMF. Based on the ability of these cells to evade the reticuloendothelial system, these complexes combined with an AMF should be considered as a potentially powerful tool for tumour therapy.Comment: In Press. 33 pages, 11 figure

    Determining R-parity violating parameters from neutrino and LHC data

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    In supersymmetric models neutrino data can be explained by R-parity violating operators which violate lepton number by one unit. The so called bilinear model can account for the observed neutrino data and predicts at the same time several decay properties of the lightest supersymmetric particle. In this paper we discuss the expected precision to determine these parameters by combining neutrino and LHC data and discuss the most important observables. We show that one can expect a rather accurate determination of the underlying R-parity parameters assuming mSUGRA relations between the R-parity conserving ones and discuss briefly also the general MSSM as well as the expected accuracies in case of a prospective e+ e- linear collider. An important observation is that several parameters can only be determined up to relative signs or more generally relative phases.Comment: 13 pages, 13 figure

    Where are the black caimans, Melanosuchus niger (Crocodylia: Alligatoridae), in the Xingu River basin, Brazil?

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    The black caiman, Melanosuchus niger (Spix, 1825), which can reach a length of 6 meters (Medem, 1981), was considered endangered due to intense hunting for its skin in the 1970s (Rebelo and Magnusson, 1983), but densities in several areas have recovered after the implementation of environmental laws and conservation programs (Da Silveira and Thorbjarnason, 1999), as well as changes in contraband routes.Na publicação: Zilca Campos

    Long‐Term Survival After Choriocarcinoma Transmitted by Liver Graft: A Successful Report in Pediatric Transplantation

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    Background: LT is the standard of care for many pediatric liver disorders. Although long-term outcomes have improved, some rare complications such as transmission of occult donor tumors have been reported. Case report: An adolescent diagnosed with tyrosinemia was submitted to LT from a previous healthy donor due to HCC. Almost 8 months after LT, the patient presented a nodular hepatic lesion. Clinically, he had mild weight loss, lower limb edema, and gynecomastia. Thorax CT found lesions in the left lung parenchyma, which showed no increased uptake in PET SCAN. Liver biopsy revealed a carcinoma with desmoplastic stroma. ISS was withdrawn, and palliative chemotherapy was started for presumptive HCC relapse. AFP remained normal, but HCG had reached unexpected values of 1984 IU/L. As we requested detailed information about the other organ recipients from the same donor, we found that one of them passed away due to disseminated tumor. Five months after the beginning of chemotherapy, the patient underwent resection of liver segments V and VI. Histological examination confirmed liver metastatic choriocarcinoma. At the time of writing, with 11 years of follow-up, the patient had sustained remission with no signs of relapse. Discussion: This case reports a diagnostic challenge in an adolescent with a particular unique background and a very rare pattern of tumor transmission. The authors aim to highlight the risk of cancer-bearing organs reveled post-LT and to testimony the experience of the successful outcome after a choriocarcinoma transmitted by liver graft.info:eu-repo/semantics/publishedVersio
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