A band is a semigroup consisting of idempotents. It is proved that for any field K and any band S with finitely many components, the semigroup algebra K[S] can be embedded in upper triangular matrices over a commutative K-algebra. The proof of a theorem of Malcev [4, Theorem 10] on embeddability of algebras into matrix algebras over a field is corrected and it is proved that if S = F ∪ E is a b...

A class-F high efficiency GaN power amplifier (PA) for dual band operation at 2.14 GHz and 2.35 GHz is proposed. A novel dual band harmonic-rejection load network, which controls the terminating impedances of the second and third harmonics, and contributes greatly to efficiency improvement of PA, is described. In addition, a matching network which guarantees the high efficiency and gain of PA f...

Laves-phase Nb(1+c)Fe(2-c) is a rare itinerant intermetallic compound exhibiting magnetic quantum criticality at c(cr)∼1.5%Nb excess; its origin, and how alloying mediates it, remains an enigma. For NbFe(2), we show that an unconventional band critical point above the Fermi level E(F) explains most observations and that chemical alloying mediates access to this unconventional band critical poin...

Let X be a compact 2-manifold with nonempty boundary ∂X and let f : (X, ∂X) → (X, ∂X) be a boundary-preserving map. Denote by MF∂ [f ] the minimum number of fixed point among all boundary-preserving maps that are homotopic through boundary-preserving maps to f . The relative Nielsen number N∂(f) is the sum of the number of essential fixed point classes of the restriction f̄ : ∂X → ∂X and the num...

Oscillator strengths for 48 rotational lines in the 0È0 band of the transition of a c4@ 1&u`^X1&g` 14N2, prominent feature in planetary airglow emissions, have been determined from vacuum ultraviolet photoabsorption spectra recorded with an instrumental resolution of D6.5] 10~4 nm (resolving power B150,000). The sum of the integrated cross sections over all measured lines, including six lines a...

— Z\ centers have been produced in strontium-doped KC1 by a new method which allows one to send negative ion vacancies and electrons separately through the crystal. This new method of producing Z\ centers confirms that the Z\ center contains an F center as a component and gives direct experimental evidence for the existence of an intermediate product in the Zi center formation. This intermediat...

This paper presents two broadband LNAs covering the frequency ranges from 47 to 77 GHz and 73 to 140 GHz, with peak gain above 20 dB. A proposed Ttype matching topology has been adopted in both circuits to achieve the wide bandwidth. While the V-band LNA achieves the design target, the bandwidth in W/F-band is reduced to 73-140 GHz, with a mid-band gain of 20 dB. The measured NF is below 7.2 dB...

The influences of the filling rate on the photonic band gap properties of the two dimensional hex photonic crystals are investigated using the finite-difference time-domain method. When the filling rate f varies from 0.227 to 0.735 reminding the refractive index as 5, the number of the photonic band gaps decreases from 5 to 2 bands, the width of the photonic band gap between the transmit peaks ...

Two high efficiency Ku-band pHEMT power amplifier MMICs are presented in this paper. A single stage, high efficiency amplifier provides a peak power added efficiency of 57.6% with 10.5 dB associated gain and 26.5 dBm output power into a 50Ω load at 14 GHz. Additionally, a dual stage, high gain amplifier provides a peak power added efficiency of 50.4% with 19.7 dB associated gain and 27.5 dBm ou...

In a class F power amplifier, producing the required short circuit at even harmonics and the open circuit at the odd harmonics at the active device output can substantially increase efficiency of the power amplifier [1, 2]. With such harmonic tuning, the voltage across the active device output and current through it do not contain harmonics of the same order simultaneously. In practice, it is v...