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

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

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

Economic implications for Turkey of a customs union with the European Union

Turkey and the European Union (EU) have agreed to implement a customs union. This means Turkey will eliminate its tariffs and levies on imports on manufactured products from the EU. Turkey will also apply EU's"common external tariff"on imports from third countries. Turkey will be obligated by 20001 to provide preferential access to its markets to all countries to which the EU grants such access. Since Turkey is both eliminating tariffs on EU imports and reducing tariffs on imports from third countries, it will become a rather open economy in nonagricultural sectors. And since preferential access agreements with third countries will typically be reciprocal, Turkish exporters can expect improved access to those markets. According to the authors, Turkey's biggest gains from the customs union arrangement will come from this improved access to third country markets. Using a comparative static computable general equilibrium model of Turkey, they estimate that Turkey stands to gain between 1 and 1.5 percent of gross domestic product (GDP) annually from the customs union arrangement with the EU, depending on what complementary policies it adopts. They also estimate that lost tariff revenues will amount to 1.4 percent of GDP. For Turkey to avoid worsening its fiscal deficit, it must find ways to reduce expenditures or increase revenues. Its best choice is to reduce expenditures through accelerating privatization of state-owned enterprises which will generate a number of macroeconomic and efficiency benefits in addition to the fiscal benefits. If a value-added tax (VAT) is used as a replacement tax, they estimate that VAT rates must increase 16.2 percent in each sector to compensate for the revenue losses from implementing the full customs union. But uniform application of the VAT would allow the VAT rates to fall while still compensating for the loss from reduced tariffs and would increase the welfare gain from the customs union.Economic Theory&Research,Environmental Economics&Policies,Trade Policy,Export Competitiveness,Trade Finance and Investment,Trade and Regional Integration,Trade Policy,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Environmental Economics&Policies

Piecemeal trade reform in partially liberalized economies : an evaluation for Turkey

Turkey undertook a major liberalization of trade policy in the 1980s. Import quotas disappeared, the Turkish lira was made convertible, and tariffs are generally lower. Those changes and the export subsidies that remain have removed the anti-export bias from Turkey's external incentive regime. Using a 40-sector computable general equilibrium model, the authors consider several more trade liberalization options available to the Turkish government. They conclude that uniformity of tariffs and export subsidies would substantially improve Turkey's welfare. Although the"Ramsey"optimal import taxation would call for non-uniform import taxes inversely proportional to the elasticity of import demand in each sector, the observed dispersion of tariff structure in Turkey is inconsistent with optimal departures from uniform protection. In fact, uniformity achieves an extremely high proportion of the benefits of full trade liberalization because, in the absence of a general anti-export bias, theprincipal distortion remaining in the trade regime derives from dispersion of the tariff and, especially the export subsidy structure. An increasing number of developing countries - including Chile, Indonesia, Mexico, and Poland - have in recent years undertaken extensive trade liberalization. It is no longer clear that these economies retain an anti-export bias in their trade regime. Perhaps the most important policy conclusion the authors reach is that one must be wary of advocating piecemeal reform of tariffs or export subsidies alone. Piecemeal across-the-board tariff reductions do not always improve welfare; they must generally be coordinated with reductions in export subsidies to ensure improved welfare. The authors counterfactually assume that Turkey's tariffs are at the 1985 level which reintroduces an anti-export bias of import tariffs. In this case, piecemeal tariff reduction to the 1989 level is beneficial. Even small export subsidies are not always beneficial, despite the rule of thumb that small export subsidies are a welfare-enhancing offset to the anti-export bias of import tariffs. Export subsidies in Turkey are highly dispersed, and piecemeal reductions in the export subsidies reduce that dispersion. When the authors counterfactually impose uniformity of tariffs and export subsidies, they note that small export subsidies are beneficial as a piecemeal policy for offsetting the anti-export bias. Policymakers in developing countries have occasionally applied export subsidies in individual sectors with high tariffs as a means of encouraging exports in a sector that may otherwise rely on the highly protected domestic market. The authors show that in Turkey high export subsidies in sectors with high tariffs are particularly counterproductive - because at the multisector level the distortion introduced by the export subsidy dominates the reduction in anti-export bias. Turkey's proposed policy of harmonizing its tariff to the European Community's (EC's) common external tariff would yield only small welfare changes. Harmonizing the EC tariffs will require lowering tariffs below already low levels, in the presence of export subsidies almost as large as the existing average effective tariff rate. However harmonizing to the EC tariff structure can be beneficial if at the same time export subsidies are removed or reduced.Environmental Economics&Policies,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Economic Theory&Research,Tax Law,Trade Policy

Chile's regional arrangements and the Free Trade Agreement of the Americas : the importance of market access

Using a multisector, computable general equilibrium model, the authors examine Chile's strategy of negotiating bilateral free trade agreements with all of its significant trading partners (referring to this policy as additive regionalism). They also evaluate the Free Trade Agreement of the Americas (FTAA) and global free trade. Among Chile's bilateral regional agreements, only Chile's agreements with"Northern"partners provide enough market access to offset the costs to Chile of trade diversion. Because of preferential market access, however, additive regionalism is likely to provide Chile with many times as many gains as the static welfare gains from unilateral free trade. The authors find that at least one partner country loses from each of the regional trade agreements they consider, and excluded countries as a group they always lose. They estimate that the FTAA produces large welfare gains for the members, with the European Union being the big loser. Gains to the world from global free trade are estimated to be at least 36 times greater than gains from the FTAA. Even countries of the Americas in aggregate gain more from global free trade than from the FTAA.Rules of Origin,Economic Theory&Research,Environmental Economics&Policies,Trade Policy,Payment Systems&Infrastructure,TF054105-DONOR FUNDED OPERATION ADMINISTRATION FEE INCOME AND EXPENSE ACCOUNT,Trade and Regional Integration,Economic Theory&Research,Environmental Economics&Policies,Rules of Origin

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