Performances of Hybrid Amplitude Shape Modulation for UWB Communications Systems over AWGN Channel in a Single and Multi-User Environment

This paper analyzes the performance of the hybrid Amplitude Shape Modulation (h-ASM) scheme for the time-hopping ultra-wideband (TH-UWB) communication systems in the single and multi-user environment. h-ASM is the combination of Pulse Amplitude Modulation (PAM) and Pulse Shape Modulation (PSM) based on modified Hermite pulses (MHP). This scheme is suitable for high rate data transmission applications because b = log2(MN) bits can be mapped with one waveform. The channel capacity and error probability over AWGN channel are derived and compared with other modulation schemes

On generalizations of Ostrowski inequality via Euler harmonic identities

Copyright © 2002 L. J. Dedić et al. This work is licensed under a Creative Commons License.Some generalizations of Ostrowski inequality are given, by using some Euler identities involving harmonic sequences of polynomials.L. J. Dedić, M. Matić, J. Pečarić, and A. Vukeli

A Simple Signal Shaper for GMSK/GFSK and MSK Modulator Based on Sigma-Delta Look-up Table

Due to wide power spectrums of rectangular data streams, it is important for base-band signals to be heavily band limited before modulation. That can be achieved by pulse shaping of rectangular bits. Some of the most common are a half-sine pulse shaper and a Gaussian pulse shaper which are used in Minimum Shift Keying (MSK), Gaussian Minimum Shift Keying (GMSK) and Gaussian Frequency Shift Keying (GFSK) modulations, respectively. The most common solutions of such shapers use PCM based look-up-table (LUT), which requires an nbit D/A converter. We proposed the use of a 1-bit Sigma Delta Modulation (SDM) LUT, which results in smaller ROM capacity, a 1-bit wide output word, and a simple1-bit D/A converter realized as an out-of-chip first-order lowpass RC filter, or an in-chip charge pump. This article describes a simple, but efficient SDM LUT-based half-sine and Gaussian shaper that can be used for generation of MSK and GMSK/GFSK modulated signals. Oscillograms and power spectrums are measured on SDM LUT realized in FLEX AlteraTM PLD, for a 10-bit pseudo-noise sequence test input signal

Observation of the onset of strong scattering on high frequency acoustic phonons in densified silica glass

The linewidth of longitudinal acoustic waves in densified silica glass is obtained by inelastic x-ray scattering. It increases with a high power alpha of the frequency up to a crossover where the waves experience strong scattering. We find that \alpha is at least 4, and probably larger. Resonance and hybridization of acoustic waves with the boson-peak modes seems to be a more likely explanation for these findings than Rayleigh scattering from disorder.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Letter

Positive temperature versions of two theorems on first-passage percolation

The estimates on the fluctuations of first-passsage percolation due to Talagrand (a tail bound) and Benjamini--Kalai--Schramm (a sublinear variance bound) are transcribed into the positive-temperature setting of random Schroedinger operators.Comment: 15 pp; to appear in GAFA Seminar Note

Living IoT: A Flying Wireless Platform on Live Insects

Sensor networks with devices capable of moving could enable applications ranging from precision irrigation to environmental sensing. Using mechanical drones to move sensors, however, severely limits operation time since flight time is limited by the energy density of current battery technology. We explore an alternative, biology-based solution: integrate sensing, computing and communication functionalities onto live flying insects to create a mobile IoT platform. Such an approach takes advantage of these tiny, highly efficient biological insects which are ubiquitous in many outdoor ecosystems, to essentially provide mobility for free. Doing so however requires addressing key technical challenges of power, size, weight and self-localization in order for the insects to perform location-dependent sensing operations as they carry our IoT payload through the environment. We develop and deploy our platform on bumblebees which includes backscatter communication, low-power self-localization hardware, sensors, and a power source. We show that our platform is capable of sensing, backscattering data at 1 kbps when the insects are back at the hive, and localizing itself up to distances of 80 m from the access points, all within a total weight budget of 102 mg.Comment: Co-primary authors: Vikram Iyer, Rajalakshmi Nandakumar, Anran Wang, In Proceedings of Mobicom. ACM, New York, NY, USA, 15 pages, 201

A Sublinear Variance Bound for Solutions of a Random Hamilton Jacobi Equation

We estimate the variance of the value function for a random optimal control problem. The value function is the solution $w^\epsilon$ of a Hamilton-Jacobi equation with random Hamiltonian $H(p,x,\omega) = K(p) - V(x/\epsilon,\omega)$ in dimension $d \geq 2$. It is known that homogenization occurs as $\epsilon \to 0$, but little is known about the statistical fluctuations of $w^\epsilon$. Our main result shows that the variance of the solution $w^\epsilon$ is bounded by $O(\epsilon/|\log \epsilon|)$. The proof relies on a modified Poincar\'e inequality of Talagrand

Our Evolving Understanding of the Mechanism of Quinolones

The maintenance of DNA supercoiling is essential for the proper regulation of a plethora of biological processes. As a consequence of this mode of regulation, ahead of the replication fork, DNA replication machinery is prone to introducing supercoiled regions into the DNA double helix. Resolution of DNA supercoiling is essential to maintain DNA replication rates that are amenable to life. This resolution is handled by evolutionarily conserved enzymes known as topoisomerases. The activity of topoisomerases is essential, and therefore constitutes a prime candidate for targeting by antibiotics. In this review, we present hallmark investigations describing the mode of action of quinolones, one of the antibacterial classes targeting the function of topoisomerases in bacteria. By chronologically analyzing data gathered on the mode of action of this imperative antibiotic class, we highlight the necessity to look beyond primary drug-target interactions towards thoroughly understanding the mechanism of quinolones at the level of the cell. Keywords: antibiotics; quinolones; topoisomerases; DNA replication; DNA supercoilin

The Error and Repair Catastrophes: A Two-Dimensional Phase Diagram in the Quasispecies Model

This paper develops a two gene, single fitness peak model for determining the equilibrium distribution of genotypes in a unicellular population which is capable of genetic damage repair. The first gene, denoted by $\sigma_{via}$, yields a viable organism with first order growth rate constant $k > 1$ if it is equal to some target ``master'' sequence $\sigma_{via, 0}$. The second gene, denoted by $\sigma_{rep}$, yields an organism capable of genetic repair if it is equal to some target ``master'' sequence $\sigma_{rep, 0}$. This model is analytically solvable in the limit of infinite sequence length, and gives an equilibrium distribution which depends on \mu \equiv L\eps , the product of sequence length and per base pair replication error probability, and \eps_r , the probability of repair failure per base pair. The equilibrium distribution is shown to exist in one of three possible ``phases.'' In the first phase, the population is localized about the viability and repairing master sequences. As \eps_r exceeds the fraction of deleterious mutations, the population undergoes a ``repair'' catastrophe, in which the equilibrium distribution is still localized about the viability master sequence, but is spread ergodically over the sequence subspace defined by the repair gene. Below the repair catastrophe, the distribution undergoes the error catastrophe when $\mu$ exceeds \ln k/\eps_r , while above the repair catastrophe, the distribution undergoes the error catastrophe when $\mu$ exceeds $\ln k/f_{del}$, where $f_{del}$ denotes the fraction of deleterious mutations.Comment: 14 pages, 3 figures. Submitted to Physical Review