15,975 research outputs found
Thermoelectric and thermal rectification properties of quantum dot junctions
The electrical conductance, thermal conductance, thermal power and figure of
merit (ZT) of semiconductor quantum dots (QDs) embedded into an insulator
matrix connected with metallic electrodes are theoretically investigated in the
Coulomb blockade regime. The multilevel Anderson model is used to simulate the
multiple QDs junction system. The charge and heat currents in the sequential
tunneling process are calculated by the Keldysh Green function technique. In
the linear response regime the ZT values are still very impressive in the small
tunneling rates case, although the effect of electron Coulomb interaction on ZT
is significant. In the nonlinear response regime, we have demonstrated that the
thermal rectification behavior can be observed for the coupled QDs system,
where the very strong asymmetrical coupling between the dots and electrodes,
large energy level separation between dots and strong interdot Coulomb
interactions are required.Comment: 8 page and 14 figure
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Wireless Inference-based Notification (WIN) without Packet Decoding
We consider ultra-energy-efficient wireless transmission of notifications in sensor networks. We argue that the usual practice where a receiver decodes packets sent by a remote node to acquire its state or message is suboptimal in energy use. We propose an alternative approach where a receiver first (1) performs physical-layer matched filtering on arrived packets without actually decoding them at the link layer or higher layer, and then (2) based on the matching results infers the sender's state or message from the time-series pattern of packet arrivals. We show that hierarchical multi-layer inference can be effective for this purpose in coping with channel noise. Because packets are not required to be decodable by the receiver, the sender can reach a farther receiver without increasing the transmit power or, equivalently, a receiver at the same distance with a lower transmit power. We call our scheme Wireless Inference-based Notification (WIN) without Packet Decoding. We demonstrate by analysis and simulation that WIN allows a sender to multiply its notification distance. We show how senders can realize these energy-efficiency benefits with unchanged system and protocols; only receivers, which normally are larger systems than senders and have ample computing and power resources for WIN-related processing.Engineering and Applied Science
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Liquid biopsy genotyping in lung cancer: ready for clinical utility?
Liquid biopsy is a blood test that detects evidence of cancer cells or tumor DNA in the circulation. Despite complicated collection methods and the requirement for technique-dependent platforms, it has generated substantial interest due, in part, to its potential to detect driver oncogenes such as epidermal growth factor receptor (EGFR) mutants in lung cancer. This technology is advancing rapidly and is being incorporated into numerous EGFR tyrosine kinase inhibitor (EGFR-TKI) development programs. It appears ready for integration into clinical care. Recent studies have demonstrated that biological fluids such as saliva and urine can also be used for detecting EGFR mutant DNA through application other user-friendly techniques. This review focuses on the clinical application of liquid biopsies to lung cancer genotyping, including EGFR and other targets of genotype-directed therapy and compares multiple platforms used for liquid biopsy
Majorana zero modes in a quantum Ising chain with longer-ranged interactions
A one-dimensional Ising model in a transverse field can be mapped onto a
system of spinless fermions with p-wave superconductivity. In the weak-coupling
BCS regime, it exhibits a zero energy Majorana mode at each end of the chain.
Here, we consider a variation of the model, which represents a superconductor
with longer ranged kinetic energy and pairing amplitudes, as is likely to occur
in more realistic systems. It possesses a richer zero temperature phase diagram
and has several quantum phase transitions. From an exact solution of the model
these phases can be classified according to the number of Majorana zero modes
of an open chain: 0, 1, or 2 at each end. The model posseses a multicritical
point where phases with 0, 1, and 2 Majorana end modes meet. The number of
Majorana modes at each end of the chain is identical to the topological winding
number of the Anderson's pseudospin vector that describes the BCS Hamiltonian.
The topological classification of the phases requires a unitary time-reversal
symmetry to be present. When this symmetry is broken, only the number of
Majorana end modes modulo 2 can be used to distinguish two phases. In one of
the regimes, the wave functions of the two phase shifted Majorana zero modes
decays exponentially in space but but in an oscillatory manner. The wavelength
of oscillation is identical to the asymptotic connected spin-spin correlation
of the XY-model in a transverse field to which our model is dual.Comment: 11 pages, 8 figures; brief clarifying comments added; few new
references; this version is accepted in Phys. Rev.
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