299 research outputs found

    Holstein model and Peierls instability in 1D boson-fermion lattice gases

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    We study an ultracold bose-fermi mixture in a one dimensional optical lattice. When boson atoms are heavier then fermion atoms the system is described by an adiabatic Holstein model, exhibiting a Peierls instability for commensurate fermion filling factors. A Bosonic density wave with a wavenumber of twice the Fermi wavenumber will appear in the quasi one-dimensional system.Comment: 5 pages, 4 figure

    Rough Set Theory Applied To Hyper BCK-Algebra

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    The aim of this paper is to introduce the notions of lower and upper approximation of a subset of a hyper BCK-algebra with respect to a hyper BCK-ideal. We give the notion of rough hyper subalgebra and rough hyper BCK-ideal, too, and we investigate their properties

    Disordered Carbon nanotube alloys in the Effect Medium Super Cell Approximation

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    We investigate a disordered single-walled carbon nanotube (SWCNT) in an effective medium super cell approximation (EMSCA). First type of disorder that we consider is the presence of vacancies. Our results show that the vacancies induce some bound states on their neighbor host sites, leading to the creation of a band around the Fermi energy in the SWCNT average density of states.Second type of disorder considered is a substitutional BcbNcnC1cbcnB_{cb}N_{cn}C_{1-cb-cn} alloy due to it's applications in hetrojunctions. We found that for a fixed boron (nitrogen) concentration, by increasing the nitrogen (boron) concentration the averaged semiconducting gap, EgE_{g}, decreases and at a critical concentration it disappears. A consequence of our results for nano electronic devices is that by changing the boron(nitrogen) concentration, one can make a semiconductor SWCNT with a pre-determined energy gap.Comment: 4 page

    Ferromagnetic semiconductor single wall carbon nanotube

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    Possibility of a ferromagnetic semiconductor single wall carbon nanotube (SWCNT), where ferromagnetism is due to coupling between doped magnetic impurity on a zigzag SWCNT and electrons spin, is investigate. We found, in the weak impurity-spin couplings, at low impurity concentrations the spin up electrons density of states remain semiconductor while the spin down electrons density of states shows a metallic behavior. By increasing impurity concentrations the semiconducting gap of spin up electrons in the density of states is closed, hence a semiconductor to metallic phase transition is take place. In contrast, for the case of strong coupling, spin up electrons density of states remain semiconductor and spin down electron has metallic behavior. Also by increasing impurity spin magnitude, the semiconducting gap of spin up electrons is increased.Comment: 10 pages and 9 figure

    Intranasal administration of endometrial mesenchymal stem cells as a suitable approach for Parkinson�s disease therapy

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    This study aimed to investigate the therapeutic effects of intranasal administration of human endometrium-derived stem cells (HEDSCs) in the mouse model of Parkinson�s disease (PD). Thirty days after intrastriatal injection of 6-OHDA, HEDSCs were administrated intranasally in three doses (104, 5 � 104 and 105 cells µl�1). During 120 days after stem cell administration, behavioral tests were examined. Then the mice were sacrificed and the fresh section of the substantia nigra pars compacta (SNpc) was used for detection of HEDSCs-GFP labeled by fluorescence microscopy method. In addition, immunohistochemistry was used to assay GFP, human neural Nestin, and tyrosine hydroxylase (TH) markers in the fixed brain tissue at the SNpc. Our data revealed that behavioral parameters were significantly improved after cell therapy. Fluorescence microscopy assay in fresh tissue and GFP analysis in fixed tissue were showed that the HEDSCs-GFP labeled migrated to SNpc. The data from immunohistochemistry revealed that the Nestin as a differential neuronal biomarker was expressed in SNpc. Also, TH as a dopaminergic neuron marker significantly increased after HEDSCs therapy in an optimized dose 5 � 104 cells µl�1. Our results suggest that intranasal administration of HEDSCs improve the PD symptoms in the mouse model of PD dose-dependent manner as a noninvasive method. © 2019, Springer Nature B.V

    Petrology, geochemistry and tectonomagmatic evolution of Hezar Igneous Complex (Rayen - south of Kerman - Iran): the first description of an arc remnant of the Neotethyan subduction zone

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    The Hezar Igneous Complex (HIC) in the south-eastern part of Urumieh-Dokhtar magmatic arc, is the most prominent magmatic feature in the Kerman Porphyry Copper Belt, that understanding magmatic evolution of which may shed light on the tectonomagmatic development of this less-studied part of an important magmatic arc in the Neotethys realm. The HIC has been developed in the the intersection of the N-S striking Sabzevaran fault and the NW-SE striking Rafsanjan-Rayen fault. It is indicated that the possible place of the conduit and vent is in Jalas Mountain which has been splitted later by the Sabzevaran fault into Minor and Major Jalas. The current summit had been constructed by ascending magma chamber under the HIC that constitutes the Kamali Mountain at the south of the summit. Some plutonic rocks of the HIC are exposed at Kamali Mountain. The subalkaline rocks of this complex mainly are composed of different pyroclastic and lava flow rocks, acidic to basic in composition, showing the evidences of fractional crystallization and mineral segregation. Sequential explosive and effusive eruptions with Strombolian to Vulcanian types are evident in the successive volcanic layers. The compositional trend shows the melting of spinel lherzolite, not garnet lherzolite. The subduction-related mechanism of the magma genesis has been indicated by IAB nature of the magma formation in geochemical diagrams.publishe

    Superconducing Alloys with Weak and Strong Scattering: Anderson's Theorem and a Superconductor-Insulator Transition

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    We have studied the effects of strong impurity scattering on disordered superconductors beyond the low impurity concentration limit. By applying the full CPA to a superconductiong A-B binary alloy, we calculated the fluctuations of the local order parameters ΔA,ΔB\Delta_{A}, \Delta_{B} and charge densities, nA,nBn_{A}, n_{B} for weak and strong on site disorder. We find that for narrow band alloy s-wav e superconductors the conditions for Anderson's theorem are satisfied in general only for the case of particle-hole symmetry. In this case it is satisfied regardless whether we are in the weak or strong scattering regimes. Interestingly, we find that strong scattering leads to band splitting and in this regime for any band filling we have a critical concentration where a superconductor-insulator quantum phase transition occurs at T=0.Comment: 28 pages, 13 figure

    Left atrial drainage of the right superior vena cava: A case report

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    An isolated right superior vena cava (RSVC) draining into the left atrium represents a very rare congenital malformation, especially in the absence of a partial anomalous pulmonary venous return. This condition leads to hypoxemia, cyanosis, and clubbing without any other signs of heart defects. We describe an 8-year-old girl, who was referred to our hospital due to unexplained cyanosis. Segmental approach in transthoracic echocardiography showed left atrial drainage of the RSVC, which was subsequently confirmed by contrast echocardiography and angiography. Surgical repair via trans-section and anastomosis of the superior vena cava to the right atrium was performed to prevent the complications of right-to-left shunting and cyanosis. During a 4-year follow-up, the patient remained in very good clinical status and her serial echocardiography was normal except for very mild left atrial and left ventricular enlargement. © 2018, Tehran Heart Center. All rights reserved

    Structural Analysis of a Repetitive Protein Sequence Motif in Strepsirrhine Primate Amelogenin

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    Strepsirrhines are members of a primate suborder that has a distinctive set of features associated with the development of the dentition. Amelogenin (AMEL), the better known of the enamel matrix proteins, forms 90% of the secreted organic matrix during amelogenesis. Although AMEL has been sequenced in numerous mammalian lineages, the only reported strepsirrhine AMEL sequences are those of the ring-tailed lemur and galago, which contain a set of additional proline-rich tandem repeats absent in all other primates species analyzed to date, but present in some non-primate mammals. Here, we first determined that these repeats are present in AMEL from three additional lemur species and thus are likely to be widespread throughout this group. To evaluate the functional relevance of these repeats in strepsirrhines, we engineered a mutated murine amelogenin sequence containing a similar proline-rich sequence to that of Lemur catta. In the monomeric form, the MQP insertions had no influence on the secondary structure or refolding properties, whereas in the assembled form, the insertions increased the hydrodynamic radii. We speculate that increased AMEL nanosphere size may influence enamel formation in strepsirrhine primates
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