13,794 research outputs found

    The effective mass of atom-radiation field system and the cavity-field Wigner distribution in the presence of a homogeneous gravitational field in the Jaynes-Cummings model

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    The effective mass that approximately describes the effect of a classical homogeneous gravitational field on an interacting atom-radiation field system is determined within the framework of the Jaynes-Cummings model. By taking into account both the atomic motion and gravitational field, a full quantum treatment of the internal and external dynamics of the atom is presented. By solving exactly the Schrodinger equation in the interaction picture, the evolving state of the system is found. Influence of a classical homogeneous gravitational field on the energy eigenvalues, the effective mass of atom-radiation field system and the Wigner distribution of the radiation field are studied, when initially the radiation field is prepared in a coherent state and the two-level atom is in a coherent superposition of the excited and ground states.Comment: 12 pages, 9 figure

    Mask Programmable CMOS Transistor Arrays for Wideband RF Integrated Circuits

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    A mask programmable technology to implement RF and microwave integrated circuits using an array of standard 90-nm CMOS transistors is presented. Using this technology, three wideband amplifiers with more than 15-dB forward transmission gain operating in different frequency bands inside a 4-22-GHz range are implemented. The amplifiers achieve high gain-bandwidth products (79-96 GHz) despite their standard multistage designs. These amplifiers are based on an identical transistor array interconnected with application specific coplanar waveguide (CPW) transmission lines and on-chip capacitors and resistors. CPW lines are implemented using a one-metal-layer post-processing technology over a thick Parylene-N (15 mum ) dielectric layer that enables very low loss lines (~0.6 dB/mm at 20 GHz) and high-performance CMOS amplifiers. The proposed integration approach has the potential for implementing cost-efficient and high-performance RF and microwave circuits with a short turnaround time

    The effect of spin-orbit interaction on entanglement of two-qubit Heisenberg XYZ systems in an inhomogeneous magnetic field

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    The role of spin-orbit interaction on the ground state and thermal entanglement of a Heisenberg XYZ two-qubit system in the presence of an inhomogeneous magnetic field is investigated. For a certain value of spin-orbit parameter DD, the ground state entanglement tends to vanish suddenly and when DD crosses its critical value DcD_c, the entanglement undergoes a revival. The maximum value of the entanglement occurs in the revival region. In finite temperatures there are revival regions in DTD-T plane. In these regions, entanglement first increases with increasing temperature and then decreases and ultimately vanishes for temperatures above a critical value. This critical temperature is an increasing function of DD, thus the nonzero entanglement can exist for larger temperatures. In addition, the amount of entanglement in the revival region depends on the spin-orbit parameter. Also, the entanglement teleportation via the quantum channel constructed by the above system is investigated and finally the influence of the spin-orbit interaction on the fidelity of teleportation and entanglement of replica state is studied.Comment: Two columns, 9 pages, 8 Fig

    Application of Differential Transform Method to the Generalized Burgers–Huxley Equation

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    In this paper, the differential transform method (DTM) will be applied to the generalized Burgers-Huxley equation, and some special cases of the equation, say, Huxley equation and Fitzhugh-Nagoma equation. The DTM produces an approximate solution for the equation, with few and easy computations. Numerical comparison between differential transform method, Adomian decomposition method and Variational iteration method for Burgers-Huxley, Huxley equation and Fitzhugh-Nagoma equation reveal that differential transform method is simple, accurate and efficient

    Cephalometric norms for the upper airway in a healthy Hong Kong Chinese population

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    Objective. To obtain normative data for cephalometric measurements of the upper airway in the local Chinese population. Design. Observational study. Setting. University department and teaching hospital out-patient clinic. Subjects and methods. Subjects included 74 healthy patients, 29 males (age range, 18-35 years) and 45 females (age range, 16-42 years), with normal skeletal facial profile, no history of snoring, sleep apnoea, upper airway disease, tonsillectomy or adenoidectomy, obesity, of pathology in the pharynx. Twenty cephalometric airway measurements, including size of the tongue, soft palate, nasopharynx, oropharynx, hypopharynx, and relative position of the hyoid bone and valleculae were obtained. Landmarks on cephalometric radiographs were digitised and measurements were made using a specially designed computer programme. Error analysis of measurements was performed and comparison of measurements according to sex was made. Results. Significant sex dimorphism was seen for the majority of measurements, with the exception of minimal depth of the airway, oropharyngeal depth of the airway, and the soft palate angle with the hard palate. Conclusion. A minimum sagittal dimension of the upper airway was evident despite differences in measurements between sexes. Findings from this study should be a useful reference for the assessment of sleep apnoea in the local population.published_or_final_versio

    Human Peripheral Blood Derived Hematopoietic Stem Cell: History, the Isolation Methods and Investigation of Different Parameters Effects on Their Differentiation to the Body Cells

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    Blood and the system that forms it, known as the hematopoietic system, consist of many cell types with specialized functions. Red blood cells (erythrocytes) carry oxygen to the tissues. Platelets (derived from megakaryocytes) help prevent bleeding. Granulocytes (neutrophils, basophils and eosinophils) and macrophages (collectively known as myeloid cells) fight infections from bacteria, fungi, and other parasites such as nematodes (ubiquitous small worms). Some of these cells are also involved in tissue and bone remodeling and removal of dead cells. B-lymphocytes produce antibodies, while T-lymphocytes can directly kill or isolate by inflammation cells recognized as foreign to the body, including many virus-infected cells and cancer cells. Many blood cells are short-lived and need to be replenished continuously; the average human requires approximately one hundred billion new hematopoietic cells each day. The continued production of these cells depends directly on the presence of Hematopoietic Stem Cells (HSCs), the ultimate, and only, source of all these. Peripheral blood stem cells (PBSC) are rapidly becoming the primary rescue modality for autologous transplantation and are now actively being investigated in the allogeneic transplant setting. Many investigators and clinical researchers believe that PBSC are likely to replace bone marrow stem cells entirely, for use in clinical transplantation in the not too distant. Hematopoietic stem cells (HSCs) are the blood cells that give rise to all the other blood cells. They give rise to the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells). The definition of hematopoietic stem cells has changed in the last two decades. The hematopoietic tissue contains cells with long-term and short-term regeneration capacities and committed multipotent, oligopotent, and unipotent progenitors
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