2,816 research outputs found

    A neutron scattering study of the interplay between structure and magnetism in Ba(Fe1x_{1-x}Cox_{x})2_2As2_2

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    Single crystal neutron diffraction is used to investigate the magnetic and structural phase diagram of the electron doped superconductor Ba(Fe1x_{1-x}Cox_x)2_2As2_2. Heat capacity and resistivity measurements have demonstrated that Co doping this system splits the combined antiferromagnetic and structural transition present in BaFe2_2As2_2 into two distinct transitions. For xx=0.025, we find that the upper transition is between the high-temperature tetragonal and low-temperature orthorhombic structures with (TTO=99±0.5T_{\mathrm{TO}}=99 \pm 0.5 K) and the antiferromagnetic transition occurs at TAF=93±0.5T_{\mathrm{AF}}=93 \pm 0.5 K. We find that doping rapidly suppresses the antiferromagnetism, with antiferromagnetic order disappearing at x0.055x \approx 0.055. However, there is a region of co-existence of antiferromagnetism and superconductivity. The effect of the antiferromagnetic transition can be seen in the temperature dependence of the structural Bragg peaks from both neutron scattering and x-ray diffraction. We infer from this that there is strong coupling between the antiferromagnetism and the crystal lattice

    Design and fabrication of 3D-printed anatomically shaped lumbar cage for intervertebra disc (IVD) degeneration treatment

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    Spinal fusion is the gold standard surgical procedure for degenerative spinal conditions when conservative therapies have been unsuccessful in rehabilitation of patients. Novel strategies are required to improve biocompatibility and osseointegration of traditionally used materials for lumbar cages. Furthermore, new design and technologies are needed to bridge the gap due to the shortage of optimal implant sizes to fill the intervertebral disc defect. Within this context, additive manufacturing technology presents an excellent opportunity to fabricate ergonomic shape medical implants. The goal of this study is to design and manufacture a 3D-printed lumbar cage for lumbar interbody fusion. Optimisations of the proposed implant design and its printing parameters were achieved via in silico analysis. The final construct was characterised via scanning electron microscopy, contact angle, x-ray micro computed tomography (μCT), atomic force microscopy, and compressive test. Preliminary in vitro cell culture tests such as morphological assessment and metabolic activities were performed to access biocompatibility of 3D-printed constructs. Results of in silico analysis provided a useful platform to test preliminary cage design and to find an optimal value of filling density for 3D printing process. Surface characterisation confirmed a uniform coating of nHAp with nanoscale topography. Mechanical evaluation showed mechanical properties of final cage design similar to that of trabecular bone. Preliminary cell culture results showed promising results in terms of cell growth and activity confirming biocompatibility of constructs. Thus for the first time, design optimisation based on computational and experimental analysis combined with the 3D-printing technique for intervertebral fusion cage has been reported in a single study. 3D-printing is a promising technique for medical applications and this study paves the way for future development of customised implants in spinal surgical applications

    W_{1+\infty} and W(gl_N) with central charge N

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    We study representations of the central extension of the Lie algebra of differential operators on the circle, the W-infinity algebra. We obtain complete and specialized character formulas for a large class of representations, which we call primitive; these include all quasi-finite irreducible unitary representations. We show that any primitive representation with central charge N has a canonical structure of an irreducible representation of the W-algebra W(gl_N) with the same central charge and that all irreducible representations of W(gl_N) with central charge N arise in this way. We also establish a duality between "integral" modules of W(gl_N) and finite-dimensional irreducible modules of gl_N, and conjecture their fusion rules.Comment: 29 pages, Latex, uses file amssym.def (a few remarks added, typos corrected

    Noves dades sobre la producció de ceràmica medieval de Barcelona. La caracterització arqueomètrica del taller del Carrer de Carders

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    Arran de la troballa d'un taller ceràmic al carrer de Carders de Barcelona, datat entre els segles XII i XIII, s'ha dut a terme la caracterització arqueomètrica de 31 individus per tal de definir les característiques químiques i petrogràfiques de la seva producció. A més, s'han contrastat els resultats amb els obtinguts per a l'altre taller del segle XIII conegut a la ciutat, el del carrer de l'Hospital. L'estudi ha permès de definir el grup de referència (GR) del carrer de Carders, com també indicar l'existència d"individus procedents d'aquesta excavació però que es relacionen amb la producció del carrer de l'Hospital. I a la inversa, l'existència d'individus procedents del carrer de l'Hospital que es relacionen amb el carrer de Carders. Finalment, entre els materials procedents del carrer de Carders s'han identificat dues noves produccions no conegudes anteriorment

    Searches for axioelectric effect of solar axions with BGO-scintillator and BGO-bolometer detectors

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    A search for axioelectric absorption of 5.5 MeV solar axions produced in the p+d3He+γ (5.5 MeV)p + d \rightarrow {^3\rm{He}}+\gamma~(5.5~ \rm{MeV}) reaction has been performed with a BGO detectors. A model-independent limit on the product of axion-nucleon gAN3g_{AN}^3 and axion-electron gAeg_{Ae} coupling constants has been obtained: gAe×gAN3<1.9×1010| g_{Ae}\times g_{AN}^3|< 1.9\times 10^{-10} for 90\% C.L..Comment: 5 pages, 3 figures, Proceedings of the 10th Patras Workshop on Axions, WIMPs and WISP 29 June - 4 July 2014, CERN, Geneva, Switzerlan

    Renormalization group and logarithmic corrections to scaling relations in conformal sector of 4D gravity

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    We study the effective theory of the conformal factor near its infrared stable fixed point.The renormalization group equations for the effective coupling constants are found and their solutions near the critical point are obtained, providing the logarithmic corrections to scaling relations.Some cosmological applications of the running of coupling constants are briefly discussed.Comment: 9 pages,LATEX fil

    Bosonization of current-current interactions

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    We discuss a generalization of the conventional bosonization procedure to the case of current-current interactions which get their natural representation in terms of current instead of fermion number density operators. A consistent bosonization procedure requires a geometrical quantization of the hamiltonian action of WW_\infty on its coadjoint orbits. An integrable example of a nontrivial realization of this symmetry is presented by the Calogero-Sutherland model. For an illustrative nonintegrable example we consider transverse gauge interactions and calculate the fermion Green function.Comment: 15 pages, TeX, C Version 3.0, Princeton preprin

    Iron Age and Anglo-Saxon genomes from East England reveal British migration history

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    British population history has been shaped by a series of immigrations, including the early Anglo-Saxon migrations after 400 CE. It remains an open question how these events affected the genetic composition of the current British population. Here, we present whole-genome sequences from 10 individuals excavated close to Cambridge in the East of England, ranging from the late Iron Age to the middle Anglo-Saxon period. By analysing shared rare variants with hundreds of modern samples from Britain and Europe, we estimate that on average the contemporary East English population derives 38% of its ancestry from Anglo-Saxon migrations. We gain further insight with a new method, rarecoal, which infers population history and identifies fine-scale genetic ancestry from rare variants. Using rarecoal we find that the Anglo-Saxon samples are closely related to modern Dutch and Danish populations, while the Iron Age samples share ancestors with multiple Northern European populations including Britain

    Phospho-p38 MAPK expression in COPD patients and asthmatics and in challenged bronchial epithelium

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    Background: The role of mitogen-activated protein kinases (MAPK) in regulating the inflammatory response in the airways of patients with chronic obstructive pulmonary disease (COPD) and asthmatic patients is unclear. Objectives: To investigate the expression of activated MAPK in lungs of COPD patients and in bronchial biopsies of asthmatic patients and to study MAPK expression in bronchial epithelial cells in response to oxidative and inflammatory stimuli. Methods: Immunohistochemical expression of phospho (p)-p38 MAPK, p-JNK1 and p-ERK1/2 was measured in bronchial mucosa in patients with mild/moderate (n = 17), severe/very severe (n = 16) stable COPD, control smokers (n = 16), control non-smokers (n = 9), in mild asthma (n = 9) and in peripheral airways from COPD patients (n = 15) and control smokers (n = 15). Interleukin (IL)-8 and MAPK mRNA was measured in stimulated 16HBE cells. Results: No significant differences in p-p38 MAPK, p-JNK or p-ERK1/2 expression were seen in bronchial biopsies and peripheral airways between COPD and control subjects. Asthmatics showed increased submucosal p-p38 MAPK expression compared to COPD patients (p 2O2), cytomix (tumour necrosis factor-\u3b1 + IL-1\u3b2 + interferon-\u3b3) and lipopolysaccharide (LPS) upregulated IL-8 mRNA at 1 or 2 h. p38 MAPK\u3b1 mRNA was significantly increased after H2O2 and LPS treatment. JNK1 and ERK1 mRNA were unchanged after H2O2, cytomix or LPS treatments. Conclusion: p-p38 MAPK expression is similar in stable COPD and control subjects but increased in the bronchi of mild asthmatics compared to stable COPD patients. p38 MAPK mRNA is increased after bronchial epithelial challenges in vitro. These data together suggest a potential role for this MAPK in Th2 inflammation and possibly during COPD exacerbations

    First array of enriched Zn82^{82}Se bolometers to search for double beta decay

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    The R&D activity performed during the last years proved the potential of ZnSe scintillating bolometers to the search for neutrino-less double beta decay, motivating the realization of the first large-mass experiment based on this technology: CUPID-0. The isotopic enrichment in 82^{82}Se, the Zn82^{82}Se crystals growth, as well as the light detectors production have been accomplished, and the experiment is now in construction at Laboratori Nazionali del Gran Sasso (Italy). In this paper we present the results obtained testing the first three Zn82^{82}Se crystals operated as scintillating bolometers, and we prove that their performance in terms of energy resolution, background rejection capability and intrinsic radio-purity complies with the requirements of CUPID-0
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