4,756 research outputs found

    Mode mixing induced by disorder in graphene PNP junction in a magnetic field

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    We study the electron transport through the graphene PNP junction under a magnetic field and show that modes mixing plays an essential role. By using the non-equilibrium Green's function method, the space distribution of the scattering state for a specific incident modes as well the elements of the transmission and reflection coefficient matrixes are investigated. All elements of the transmission (reflection) coefficient matrixes are very different for a perfect PNP junction, but they are same at a disordered junction due to the mode mixing. The space distribution of the scattering state for the different incident modes also exhibit the similar behaviors, that they distinctly differ from each other in the perfect junction but are almost same in the disordered junction. For a unipolar junction, when the mode number in the center region is less than that in the left and right regions, the fluctuations of the total transmission and reflection coefficients are zero, although each element has a large fluctuation. These results clearly indicate the occurrence of perfect mode mixing and it plays an essential role in a graphene PNP junction transport

    Spin-dependent Rotating Wigner Molecules in Quantum dots

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    The spin-dependent trial wave functions with rotational symmetry are introduced to describe rotating Wigner molecular states with spin degree of freedom in four- and five-electron quantum dots under magnetic fields. The functions are constructed with unrestricted Hartree-Fock orbits and projection technique in long-range interaction limit. They highly overlap with the exact-diagonalized ones and give the accurate energies in strong fields. The zero points, i.e. vortices of the functions have straightforward relations to the angular momenta of the states. The functions with different total spins automatically satisfy the angular momentum transition rules with the increase of magnetic fields and explicitly show magnetic couplings and characteristic oscillations with respect to the angular momenta. Based on the functions, it is demonstrated that the entanglement entropies of electrons depend on the z-component of total spin and rise with the increase of angular momenta

    Multi-channel Wireless Networks with Infrastructure Support: Capacity and Delay

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    In this paper, we propose a novel multi-channel network with infrastructure support, called an \textit{MC-IS} network, which has not been studied in the literature. To the best of our knowledge, we are the first to study such an \textit{MC-IS} network. Our \textit{MC-IS} network is equipped with a number of infrastructure nodes which can communicate with common nodes using a number of channels where a communication between a common node and an infrastructure node is called an infrastructure communication and a communication between two common nodes is called an ad-hoc communication. Our proposed \textit{MC-IS} network has a number of advantages over three existing conventional networks, namely a single-channel wireless ad hoc network (called an \textit{SC-AH} network), a multi-channel wireless ad hoc network (called an \textit{MC-AH} network) and a single-channel network with infrastructure support (called an \textit{SC-IS} network). In particular, the \textit{network capacity} of our proposed \textit{MC-IS} network is nlog⁑n\sqrt{n \log n} times higher than that of an \textit{SC-AH} network and an \textit{MC-AH} network and the same as that of an \textit{SC-IS} network, where nn is the number of nodes in the network. The \textit{average delay} of our \textit{MC-IS} network is log⁑n/n\sqrt{\log n/n} times lower than that of an \textit{SC-AH} network and an \textit{MC-AH} network, and min⁑(CI,m)\min(C_I,m) times lower than the average delay of an \textit{SC-IS} network, where CIC_I and mm denote the number of channels dedicated for infrastructure communications and the number of interfaces mounted at each infrastructure node, respectively.Comment: 12 pages, 6 figures, 3 table

    On Capacity and Delay of Multi-channel Wireless Networks with Infrastructure Support

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    In this paper, we propose a novel multi-channel network with infrastructure support, called an MC-IS network, which has not been studied in the literature. To the best of our knowledge, we are the first to study such an MC-IS network. Our proposed MC-IS network has a number of advantages over three existing conventional networks, namely a single-channel wireless ad hoc network (called an SC-AH network), a multi-channel wireless ad hoc network (called an MC-AH network) and a single-channel network with infrastructure support (called an SC-IS network). In particular, the network capacity of our proposed MC-IS network is nlog⁑n\sqrt{n \log n} times higher than that of an SC-AH network and an MC-AH network and the same as that of an SC-IS network, where nn is the number of nodes in the network. The average delay of our MC-IS network is log⁑n/n\sqrt{\log n/n} times lower than that of an SC-AH network and an MC-AH network, and min⁑{CI,m}\min\{C_I,m\} times lower than the average delay of an SC-IS network, where CIC_I and mm denote the number of channels dedicated for infrastructure communications and the number of interfaces mounted at each infrastructure node, respectively. Our analysis on an MC-IS network equipped with omni-directional antennas only has been extended to an MC-IS network equipped with directional antennas only, which are named as an MC-IS-DA network. We show that an MC-IS-DA network has an even lower delay of c⌊2Ο€ΞΈβŒ‹β‹…CI\frac{c}{\lfloor \frac{2\pi}{\theta}\rfloor \cdot C_I} compared with an SC-IS network and our MC-IS network. For example, when CI=12C_I=12 and ΞΈ=Ο€12\theta=\frac{\pi}{12}, an MC-IS-DA network can further reduce the delay by 24 times lower that of an MC-IS network and reduce the delay by 288 times lower than that of an SC-IS network.Comment: accepted, IEEE Transactions on Vehicular Technology, 201

    Human platelets repurposed as vehicles for in vivo imaging of myeloma xenotransplants.

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    Human platelets were identified in tumors by Trousseau in 1865, although their roles in tumor microenvironments have only recently attracted the attention of cancer researchers. In this study we exploit and enhance platelet interactions in tumor microenvironments by introducing tumor-targeting and imaging functions. The first step in repurposing human platelets as vehicles for tumor-targeting was to inhibit platelet-aggregation by cytoplasmic-loading of kabiramide (KabC), a potent inhibitor of actin polymerization and membrane protrusion. KabC-Platelets can accumulate high levels of other membrane-permeable cytoxins and probes, including epidoxorubicin, carboxyfluorescein di-ester and chlorin-e6. Finally, mild reaction conditions were developed to couple tumor-targeting proteins and antibodies to KabC-platelets. Fluorescence microscopy studies showed KabC-platelets, surface-coupled with transferrin and Cy5, bind specifically to RPMI8226 and K562 cells, both of which over-express the transferrin receptor. Repurposed platelets circulate for upto 9-days a feature that increases their chance of interacting with target cells. KabC-platelets, surface-coupled with transferrin and Cy7, or chlorin-e6, and injected in immuno-compromised mice were shown to accumulate specifically in sub-cutaneous and intra-cranial myeloma xenotransplants. The high-contrast, in vivo fluorescence images recorded from repurposed platelets within early-stage myeloma is a consequence in part of their large size (Ο†~2Β΅m), which allows them to transport 100 to 1000-times more targeting-protein and probe molecules respectively. Human platelets can be configured with a plurality of therapeutic and targeting antibodies to help stage tumor environments for an immunotherapy, or with combinations of therapeutic antibodies and therapeutic agents to target and treat cardiovascular and neurologic diseases
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