Trellis-Coded Non-Orthogonal Multiple Access

In this letter, we propose a trellis-coded non-orthogonal multiple access (NOMA) scheme. The signals for different users are produced by trellis coded modulation (TCM) and then superimposed on different power levels. By interpreting the encoding process via the tensor product of trellises, we introduce a joint detection method based on the Viterbi algorithm. Then, we determine the optimal power allocation between the two users by maximizing the free distance of the tensor product trellis. Finally, we manifest that the trellis-coded NOMA outperforms the uncoded NOMA at high signal-to-noise ratio (SNR)

Catalytic RNA and synthesis of the peptide bond

We are studying whether the L-19 IVS ribozyme from Tetrahymena thermophila can catalyze the formation of the peptide bond when it is supplied with synthetic aminoacyl oligonucleotides. If this reaction works, it could give us some insight into the mechanism of peptide bond formation and the origin of coded protein synthesis. Two short oligoribonucleotides, CCCCC and a protected form of CCCCU were prepared; the former was made by the controlled hydrolysis of Poly(C), and the later by multistep chemical synthesis from the protected monomers. The homopentamer was then aminocylated using C-14 labelled Boc-protected glycine imidazolide. This aminoacylated oligo-nucleotide has now been shown to enter the active site of the L-19 IVS, and aminoacyl transfer, and peptide bond formation reactions are being sought. Our synthesis of CCCCU made us aware of the inadequacy of many of the 2'- hydroxyl protecting groups that are in use today and we therefore designed a new 2'- protecting group that is presently being tested

A large-scale one-way quantum computer in an array of coupled cavities

We propose an efficient method to realize a large-scale one-way quantum computer in a two-dimensional (2D) array of coupled cavities, based on coherent displacements of an arbitrary state of cavity fields in a closed phase space. Due to the nontrivial geometric phase shifts accumulating only between the qubits in nearest-neighbor cavities, a large-scale 2D cluster state can be created within a short time. We discuss the feasibility of our method for scale solid-state quantum computationComment: 5 pages, 3 figure

Active control of sound transmission through a hole in a large thick wall

Holes in walls of enclosures or buildings are often the weak link in the chain of sound insulation. This paper introduces an analytical model to calculate the sound transmission from a baffled rectangular hole based on the modal expansion approach, and proposes to install an active noise control system inside the hole to improve the transmission loss of the perforated wall. Different control source and error sensing strategies are investigated, and it is found that for a 30 cm thick wall with a 6 cm by 6 cm hole, an active control system with 1 control source and 1 error sensor can achieve more than 20 dB attenuation up to 2700 Hz, while that with a compound control source consisting of 4 loudspeakers, the system can achieve similar reduction up to 3900 Hz

High-Mobility Few-Layer Graphene Field Effect Transistors Fabricated on Epitaxial Ferroelectric Gate Oxides

The carrier mobility \mu of few-layer graphene (FLG) field-effect transistors increases ten-fold when the SiO_2 substrate is replaced by single-crystal epitaxial Pb(Zr_0.2Ti_0.8)O_3 (PZT). In the electron-only regime of the FLG, \mu reaches 7x10^4 cm^2/Vs at 300K for n = 2.4x10^12/cm^2, 70% of the intrinsic limit set by longitudinal acoustic (LA) phonons; it increases to 1.4x10^5 cm^2/Vs at low temperature. The temperature-dependent resistivity \rho(T) reveals a clear signature of LA phonon scattering, yielding a deformation potential D = 7.8+/-0.5 eV.Comment: 5 pages, 4 figure

Vector magnetic field sensing by single nitrogen vacancy center in diamond

In this Letter, we proposed and experimentally demonstrated a method to detect vector magnetic field with a single nitrogen vacancy (NV) center in diamond. The magnetic field in parallel with the axis of the NV center can be obtained by detecting the electron Zeeman shift, while the Larmor precession of an ancillary nuclear spin close to the NV center can be used to measure the field perpendicular to the axis. Experimentally, both the Zeeman shift and Larmor precession can be measured through the fluorescence from the NV center. By applying additional calibrated magnetic fields, complete information of the vector magnetic field can be achieved with such a method. This vector magnetic field detection method is insensitive to temperature fluctuation and it can be applied to nanoscale magnetic measurement.Comment: 5 pages, 5 figure

Spin correlated interferometry for polarized and unpolarized photons on a beam splitter

Spin interferometry of the 4th order for independent polarized as well as unpolarized photons arriving simultaneously at a beam splitter and exhibiting spin correlation while leaving it, is formulated and discussed in the quantum approach. Beam splitter is recognized as a source of genuine singlet photon states. Also, typical nonclassical beating between photons taking part in the interference of the 4th order is given a polarization dependent explanation.Comment: RevTeX, 19 pages, 1 ps figure, author web page at http://m3k.grad.hr/pavici

Secondary source and error sensing strategies for the active control of sound transmission through a small opening

© 2019 Elsevier Ltd The openings of an enclosure allow natural ventilation and light ingress but also act as a point of entry for noise of the whole structure. In this paper, the active control of the sound transmitted through a small opening in a wall formed by two infinitely-large baffles is investigated up to 4 kHz. Based on an analytical model developed with the modal expansion method, the effects of different secondary source and error sensor strategies are compared numerically for different types of primary sound fields. The upper frequency limit of effective control is found to be determined by the eigen-frequency of the acoustic modes of the opening. Experimental results with an opening of 6 cm by 6 cm on a 31.8 cm thick wall agree well with the numerical results. The upper frequency limit of effective control is found to be 2750 Hz for a single-channel system and 3900 Hz for a 4-channel system with more than 10 dB noise reduction. It is concluded that implementing active control in small openings with an appropriate secondary source and error sensing strategy can extend the frequency range of control significantly, so that the active control systems can be applied to more noise control scenarios which have both noise reduction and ventilation requirements in the middle to high frequency range

Retirement Income and Financial Market Participation in New Zealand

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