Long exciton spin memory in coupled quantum wells

Spatially indirect excitons in a coupled quantum well structure were studied by means of polarization and time resolved photoluminescence. A strong degree of circular polarization (> 50%) in emission was achieved when the excitation energy was tuned into resonance with the direct exciton state. The indirect transition remained polarized several tens of nanoseconds after the pumping laser pulse, demonstrating directly a very long relaxation time of exciton spin. The observed spin memory effect exceeds the radiative lifetime of the indirect excitons.Comment: 4 pages, 2 figure

A depolarization and attenuation experiment using the CTS satellite. Volume 1: Experiment description

An experiment for measuring precipitation attenuation and depolarization on the Communications Technology Satellite (CTS) 11.7 GHz downlink is described. Attenuation and depolarization of the signal received from the spacecraft is monitored on a 24 hour basis. Data is correlated with ground weather conditions. Theoretical models for millimeter wave propagation through rain are refined for maximum agreement with observed data. Techniques are developed for predicting and mimimizing the effects of rain scatter and depolarization on future satellite communication systems

Kualitas Produk, Harga, dan Kualitas Layanan, Pengaruhnya terhadap Kepuasan Pelanggan Kartu Prabayar Tri di Kelurahan Wawalintouan Tondano Barat

Persaingan dalam bisnis operator seluler saat ini kian meningkat seiring berkembangnya teknologi komunikasi. Hal ini menuntut Perusahaan untuk terus berinovasi dalam meningkatkan kualitas produk serta layanannya dan lebih cermat dalam menentukan harga agar Perusahan dapat bersaing dengan kompetitornya. Tujuan penelitian untuk mengetahui pengaruh kualitas produk, harga serta kualitas layanan terhadap kepuasan pelanggan kartu prabayar Tri di Kelurahan Wawalintouan Tondano Barat. Penelitian ini menggunakan metode penelitian asosiatif dengan teknik analisis regresi berganda. Sampel yang digunakan 100 responden. Hasil penelitian menunjukan kualitas produk, harga serta kualitas layanan secara simultan dan parsial berpengaruh signifikan terhadap kepuasan pelanggan kartu prabayar Tri. Manajemen PT. Hutchison 3, sebaiknya tidak cepat puas dengan pencapaian yang diperoleh, melainkan terus berinovasi agar mampu meningkatkan kualitas produk, dan layanannya sehingga Perusahaan dapat tetap bertahan mengingat persaingan dalam bidang telekomunikasi semakin ketat, juga dikarenakan semakin meningkatnya selera konsumen sebagai dampak dari perkembangan zaman yang semakin modern. . Kata kunci : kualitas produk, harga, kualitas layanan, kepuasan pelangga

The Thermal Renormalization Group for Fermions, Universality, and the Chiral Phase-Transition

We formulate the thermal renormalization group, an implementation of the Wilsonian RG in the real-time (CTP) formulation of finite temperature field theory, for fermionic fields. Using a model with scalar and fermionic degrees of freedom which should describe the two-flavor chiral phase-transition, we discuss the mechanism behind fermion decoupling and universality at second order transitions. It turns out that an effective mass-like term in the fermion propagator which is due to thermal fluctuations and does not break chiral symmetry is necessary for fermion decoupling to work. This situation is in contrast to the high-temperature limit, where the dominance of scalar over fermionic degrees of freedom is due to the different behavior of the distribution functions. The mass-like contribution is the leading thermal effect in the fermionic sector and is missed if a derivative expansion of the fermionic propagator is performed. We also discuss results on the phase-transition of the model considered where we find good agreement with results from other methods.Comment: References added, minor typos correcte

A depolarization and attenuation experiment using the CTS satellite

Rain attenuation and depolarization data collected on the communications technology satellite 11.7 GHz downlink, and changes made in equipment following rain leak damage to the parametric amplifier are discussed. A 15 GHz radar system is described

Growth of 1T ' MoTe2 by thermally assisted conversion of electrodeposited tellurium films

Molybdenum ditelluride (MoTe2) is a transition metal dichalcogenide (TMD) which has two phases stable under ambient conditions, a semiconducting (2H) and semimetallic (1T') phase. Despite a host of interesting properties and potential applications, MoTe2 is one of the less-studied TMDs, perhaps due its relatively low abundance in nature or challenges associated with its synthesis, such as the toxicity of most precursors. In this report, we describe the fabrication of thin films of phase-pure IT' MoTe2 using predeposited molybdenum and electrodeposited tellurium layers, at the relatively low temperature of 450 C. This method allows control over film geometry and over the tellurium concentration during the conversion. The MoTe2 films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, and electron microscopies. When applied as a catalyst for the hydrogen evolution reaction, the films display promising initial results. The MoTe2 films have a Tafel slope of below 70 mV dec(-1) and compare favorably with other MoTe2 catalysts reported in the literature, especially considering the inherently scalable fabrication method. The variation in electrocatalytic behavior with thickness and morphology of the films is also investigated

Weak-Field Gravity of Revolving Circular Cosmic Strings

A weak-field solution of Einstein's equations is constructed. It is generated by a circular cosmic string revolving in its plane about the centre of the circle. (The revolution is introduced to prevent the string from collapsing.) This solution exhibits a conical singularity, and the corresponding deficit angle is the same as for a straight string of the same linear energy density, irrespective of the angular velocity of the string.Comment: 13 pages, LaTe