Logarithmic-function generator

Solid-state logarithmic-function generator is compact and provides improved accuracy. Generator includes a stable multivibrator feeding into RC circuit. Resulting exponentially decaying voltage is compared with input signal. Generator output is proportional to time required for exponential voltage to decay from preset reference level to level of input signal

Phase control circuits using frequency multiplications for phased array antennas

A phase control coupling circuit for use with a phased array antenna is described. The coupling circuit includes a combining circuit which is coupled to a transmission line, a frequency multiplier circuit which is coupled to the combining circuit, and a recombining circuit which is coupled between the frequency multiplier circuit and phased array antenna elements. In a doubler embodiment, the frequency multiplier circuit comprises frequency doublers and the combining and recombining circuits comprise four-port hybrid power dividers. In a generalized embodiment, the multiplier circuit comprises frequency multiplier elements which multiply to the Nth power, the combining circuit comprises four-part hybrid power dividers, and the recombinding circuit comprises summing circuits

Phase interpolation circuits using frequency multiplication for phased arrays

Antenna phasing circuit is described with the following advantages - 1/ increased number of phased elements, 2/ current repetition for each array element, 3/ circuit simplicity, and 4/ accurate phase interpolation. This circuit functions with Huggins Scan or with nearly any other phasing system

Phased-array antenna phase control circuit using frequency multiplication

Circuit separates out, from multiplied signals, antenna element signals which have desirable phase angles and feeds them to appropriate antenna elements of phased array. System may be used in either transmitting or receiving mode

A Renormalization Group Method for Quasi One-dimensional Quantum Hamiltonians

A density-matrix renormalization group (DMRG) method for highly anisotropic two-dimensional systems is presented. The method consists in applying the usual DMRG in two steps. In the first step, a pure one dimensional calculation along the longitudinal direction is made in order to generate a low energy Hamiltonian. In the second step, the anisotropic 2D lattice is obtained by coupling in the transverse direction the 1D Hamiltonians. The method is applied to the anisotropic quantum spin half Heisenberg model on a square lattice.Comment: 4 pages, 4 figure

Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3

We report long-range ordered antiferromagnetism concomitant with local iron displacements in the spin-ladder compound BaFe$_2$Se$_3$. Short-range magnetic correlations, present at room temperature, develop into long-range antiferromagnetic order below T$_N$ = 256 K, with no superconductivity down to 1.8 K. Built of ferromagnetic Fe$_4$ plaquettes, the magnetic ground state correlates with local displacements of the Fe atoms. These iron displacements imply significant magnetoelastic coupling in FeX$_4$-based materials, an ingredient hypothesized to be important in the emergence of superconductivity. This result also suggests that knowledge of these local displacements is essential for properly understanding the electronic structure of these systems. As with the copper oxide superconductors two decades ago, our results highlight the importance of reduced dimensionality spin ladder compounds in the study of the coupling of spin, charge, and atom positions in superconducting materials

Revitalizing the Estate Tax: 5 Easy Pieces

In a previous article, we argued that contrary to the state of the law over 35 years ago — when George Cooper wrote his seminal article on the estate tax (A Voluntary Tax? New Perspectives on Sophisticated Estate Tax Avoidance, 77 Colum. L. Rev. 161 (1977))—taxpayers today generally ‘‘can reduce the value of assets subject to transfer tax in many instances only if they are willing to assume the risk that the reduction may be economically real and reduce the actual value of assets transferred to heirs or, alternatively, in narrow situations if they are willing to incur some tax risk.’’ (The Estate Tax Non-Gap: Why Repeal a Voluntary Tax?, 20 Stan. L. & Pol’y Rev. 153 (2009)) In another article, we documented the dramatic increase in income and wealth inequality over the past 30 years and the accompanying adverse social consequences and long-term negative effect on economic growth. (Occupy the Tax Code: Using the Estate Tax to Reduce Inequality and Spur Economic Growth, 40 Pepp. L. Rev. 1255 (2013)) We argued that tax policy historically has played an important role in reducing inequality and that the estate tax is a particularly apt reform vehicle in light of the role of inherited assets among the very rich and the adverse economic effects of that inherited wealth. In this article, we advance five estate and gift tax reform proposals that would generate needed revenue, reduce inequality, and contribute to economic growth: (1) disallow minority discounts when the transferred asset or business is controlled by family before and after the transfer; (2) maintain parity between the unified credit exemption amounts for the estate and gift taxes; (3) reduce the wealth transfer tax exemptions to $3.5 million, increase the maximum tax rate to 45 percent, and limit the generation-skipping transfer tax (GSST) exemption period to 50 years; (4) restrict the ability for gifts made in trust to qualify for the gift tax annual exclusion; and (5) impose a lifetime cap on the amount that can be contributed to a grantor retained annuity trust (GRAT). This article was presented on January 17 at a symposium in Malibu, California cosponsored by Pepperdine University School of Law and Tax Analysts. Twenty of the nation’s leading tax academics, practitioners, and journalists gathered to discuss the prospects for tax reform as it is affected by two crises facing Washington: dangerously misaligned spending and tax policies, resulting in a crippling$17.4 trillion national debt; and the IRS’s alleged targeting of conservative political organizations. A video recording of the symposium is available online

Multi Spectural Flourescence Imager (MSFI)

Genetic transformation with in vivo reporter genes for fluorescent proteins can be performed on a variety of organisms to address fundamental biological questions. Model organisms that may utilize an ISS imager include unicellular organisms (Saccharomyces cerevisiae), plants (Arabidopsis thaliana), and invertebrates (Caenorhabditis elegans)

A way to estimate the heavy quark thermalization rate from the lattice

The thermalization rate of a heavy quark is related to its momentum diffusion coefficient. Starting from a Kubo relation and using the framework of the heavy quark effective theory, we argue that in the large-mass limit the momentum diffusion coefficient can be defined through a certain Euclidean correlation function, involving color-electric fields along a Polyakov loop. Furthermore, carrying out a perturbative computation, we demonstrate that the spectral function corresponding to this correlator is relatively flat at small frequencies. Therefore, unlike in the case of several other transport coefficients, for which the narrowness of the transport peak makes analytic continuation from Euclidean lattice data susceptible to severe systematic uncertainties, it appears that the determination of the heavy quark thermalization rate could be relatively well under control.Comment: 17 pages. v2: clarifications and references added, published versio