Miniature capacitive accelerometer is especially applicable to telemetry

Capacitive accelerometer design enables the construction of highly miniaturized instruments having full-scale ranges from 1 g to several hundred g. This accelerometer is applicable to telemetry and can be tailored to cover any of a large number of acceleration ranges and frequency responses

Fully Constrained Majorana Neutrino Mass Matrices Using Σ(72×3)\Sigma(72\times 3)

In 2002, two neutrino mixing ansatze having trimaximally-mixed middle ($\nu_2$) columns, namely tri-chi-maximal mixing ($\text{T}\chi\text{M}$) and tri-phi-maximal mixing ($\text{T}\phi\text{M}$), were proposed. In 2012, it was shown that $\text{T}\chi\text{M}$ with $\chi=\pm \frac{\pi}{16}$ as well as $\text{T}\phi\text{M}$ with $\phi = \pm \frac{\pi}{16}$ leads to the solution, $\sin^2 \theta_{13} = \frac{2}{3} \sin^2 \frac{\pi}{16}$, consistent with the latest measurements of the reactor mixing angle, $\theta_{13}$. To obtain $\text{T}\chi\text{M}_{(\chi=\pm \frac{\pi}{16})}$ and $\text{T}\phi\text{M}_{(\phi=\pm \frac{\pi}{16})}$, the type~I see-saw framework with fully constrained Majorana neutrino mass matrices was utilised. These mass matrices also resulted in the neutrino mass ratios, $m_1:m_2:m_3=\frac{\left(2+\sqrt{2}\right)}{1+\sqrt{2(2+\sqrt{2})}}:1:\frac{\left(2+\sqrt{2}\right)}{-1+\sqrt{2(2+\sqrt{2})}}$. In this paper we construct a flavour model based on the discrete group $\Sigma(72\times 3)$ and obtain the aforementioned results. A Majorana neutrino mass matrix (a symmetric $3\times 3$ matrix with 6 complex degrees of freedom) is conveniently mapped into a flavon field transforming as the complex 6 dimensional representation of $\Sigma(72\times 3)$. Specific vacuum alignments of the flavons are used to arrive at the desired mass matrices.Comment: 20 pages, 1 figure. arXiv admin note: substantial text overlap with arXiv:1402.085

Deviations from Tribimaximal Neutrino Mixing using a Model with Δ(27)\Delta(27) Symmetry

We present a model of neutrino mixing based on the flavour group $\Delta(27)$ in order to account for the observation of a non-zero reactor mixing angle ($\theta_{13}$). The model provides a common flavour structure for the charged-lepton and the neutrino sectors, giving their mass matrices a `circulant-plus-diagonal' form. Mass matrices of this form readily lead to mixing patterns with realistic deviations from tribimaximal mixing, including non-zero $\theta_{13}$. With the parameters constrained by existing measurements, our model predicts an inverted neutrino mass hierarchy. We obtain two distinct sets of solutions in which the atmospheric mixing angle lies in the first and the second octants. The first (second) octant solution predicts the lightest neutrino mass, $m_3 \sim 29~\text{meV}$ ($m_3 \sim 65~\text{meV}$) and the $CP$ phase, $\delta_{CP} \sim -\frac{\pi}{4}$ ($\delta_{CP} \sim \frac{\pi}{2}$), offering the possibility of large observable $CP$ violating effects in future experiments.Comment: 9 pages, 3 figure

Confinement-induced Berry phase and helicity-dependent photocurrents

The photocurrent in an optically active metal is known to contain a component that switches sign with the helicity of the incident radiation. At low frequencies, this current depends on the orbital Berry phase of the Bloch electrons via the "anomalous velocity" of Karplus and Luttinger. We consider quantum wells in which the parent material, such as GaAs, is not optically active and the relevant Berry phase only arises as a result of quantum confinement. Using an envelope approximation that is supported by numerical tight-binding results, it is shown that the Berry phase contribution is determined for realistic wells by a cubic Berry phase intrinsic to the bulk material, the well width, and the well direction. These results for the magnitude of the Berry-phase effect suggest that it may already have been observed in quantum well experiments.Comment: 4 pages, 2 figure

Stark ladders as tunable far-infrared emitters

A superlattice of GaAs/Ga(1 – x)Al(x)As quantum wells forms a Stark ladder under the influence of a perpendicular electric field. A two level incoherent emitter system, formed by radiative intersubband transitions between adjacent wells, is investigated as a tunable far-infrared radiation source. Intersubband transition rates are calculated at 4, 77, and 300 K for applied fields from 0 to 40 kV cm(–1). It is shown that the quantum efficiency of the radiative emission reaches a maximum at low temperatures for a field of 32 kV cm(–1). Under these conditions the emission wavelength is 38 µm with an estimated power output of 1.1 mW. © 1998 American Institute of Physics

Study of Chromium-Frit-Type Coatings for High-Temperature Protection of Molybdenum

The achievement of more compact and efficient power plants for aircraft is dependent, among other factors, on the perfection of heat-resisting materials that are superior to those in current use. Molybdenum is one of the high-melting metals (melting point, 4750 F). It is fairly abundant and also can be worked into many of the shapes required in modern power plants. To permit its widespread use at elevated temperatures, however, some means must first be found to prevent its rapid oxidation. The application of a protective coating is one method that might be used to achieve this goal. In the present work, a number of chromium-frit-type coatings were studied. These were bonded to molybdenum specimens by firing in controlled atmospheres to temperatures in the range of 2400 to 2700 F

Trade policy options for Chile : a quantitative evaluation

Chile is currently evaluating a wide range of possible trade policies. Using a global computable general equilibrium model, the authors examine a range of trade policy and complementary tax policy options for Chile. They focus on Chile's principal preferential trade policy options: a free-trade area with MERCOSUR, a customs union with MERCOSUR, and a free trade area with NAFTA. They also examine such options as complementary tariff reduction with nonpartner countries in combination with implementing the free trade area options; unilateral or global trade liberalization; and the optimum unilateral tariff. Their principal policy conclusions: lowering Chile's tariffs preferentially or multilaterally leads to only small gains as Chile starts with a rather efficient external trade regime, uniform tariffs of 11 percent. Largely because of its efficient uniform tariff, preferential tariff reduction will reduce Chilean welfare through trade diversion, unless Chile can improve its access in the markets of partner countries. NAFTA offers enough access to benefit Chile; MERCOSUR does not, once the trade diversion costs of MERCOSUR are taken into account. Under their preferred-elasticity scenario, Chile can convert the MERCOSUR agreement from a loss to a gain if it lowers its external tariff to between 6 and 8 percent. Doing so will also increase the gains from a potential agreement with NAFTA. Chile's current value-added tax imposes distortionary costs because collection rates are nor uniform. Chile will gain if it can collect the VAT more uniformly. Tariff reductions from trade reform will require an increase in domestic taxes, so greater uniformity in domestic taxes (less distortion in replacement taxes) will maximize the benefits from trade reform. Welfare will be improved by moving toward unifromity in the VAT and lowering the Chilean tariff to between 6 and 8 percent. This model ignores dynamic gains from trade liberalization, the result of importing either a greater variety of products or more technologically advanced products.TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Environmental Economics&Policies,Trade and Regional Integration,Economic Theory&Research,Trade Policy