All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing

We developed and fabricated an all-fiber add-drop filter by recording a Bragg grating in the waist of an asymmetric mode converter-coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers. The insertion loss of the device was ~0.1 dB .A narrow spectral bandwidth (<1 nm) and a large add-drop efficiency (>90%) were also demonstrated. In addition, the filter was polarization independent.     

Dembowski semi-2-spaces

The Dembowski semi-planes are the semi-planes which were determined by P. Dembowski [3]. A Dembowski semi-i-space (i1) is an incidence structure J=(P,B,I) for which: (i) each element of B is incident with at least i+3 elements of P, and (ii) each i-residual space of J is a Dembowski semi-plane. The article [5] contained the complete classification of all Dembowski semi-1-spaces, in this article we classify all Dembowski semi-2-spaces.     

Analysis of benzo[a]pyrene diol epoxide-DNA adducts by capillary zone electrophoresis- electrospray ionization-mass spectrometry in conjunction with sample stacking

Benzo[a]pyrene diol epoxide (BPDE) was reacted in vitro with (2'-deoxy)nucleotides and with calf thymus DNA. The modified DNA was enzymatically hydrolyzed to the 5'-monophosphate nucleotides using deoxyribonuclease I (DNA-ase I), nuclease P1 and snake venom phosphodiesterase (SVP). Most of the unmodified nucleotides were removed using solid phase extraction (SPE) in a polystyrene divinylbenzene copolymer. Three adducts could be detected and identified using capillary zone electrophoresis(negative)-ion electrospray ionization-mass spectrometry (CZE-(-)-ESI-MS) in conjunction with sample stacking. This way, not only a BPDE-dGMP adduct [(M-H)(-) at m/z 648], a well-known nucleotide adduct, could be retrieved, but also a BPDE-dAMP [(M-H)(-) at m/z 632] and a BPDE-dCMP adduct [(M-H)(-) at m/z 608] could be detected for the first time. The presence of the prominent ion at m/z 195 (the deoxyribose-phosphate ion) in the three low-energy collision-activated decomposition (CAD) spectra indicated that the adducts were formed through base-alkylation. CZE-positive ion ESI-MS/MS experiments were performed to obtain further information on base-alkylation. The absence of the loss of NH(3) from the nucleobase in each CAD spectrum points to an alkylated exocyclic NH(2) position of the nucleobase. So, the three adducts could be identified as BPDE-N(2)-dGMP, BPDE-N(6)-dAMP and BPDE-N(4)-dCMP using CZE-ESI-MS and CZE-ESI-MS/MS.     

p-Brauer characters ofq-defect 0

For ap-solvable groupG the number of irreducible Brauer characters ofG with a given vertexP is equal to the number of irreducible Brauer characters of the normalizer ofP with vertexP. In this paper we prove in addition that for solvable groups one can control the number of those characters whose degrees are divisible by the largest possibleq-power dividing the order of |G|. supported by DGICYT.PB 90-0414-C03-01     

Cartan invariants and defect zero elements

In this note we prove relations between Cartan invariants in characteristc p and p defect zero elements. Exploiting duality arguments in characteristic two we show that the existence of real 2-defect zero elements is equivalent to the existence of odd diagonal entries in the Cartan matrix corresponding to real-valued Brauer characters. In addition, we present an independent and elementary proof of Theorem 3.3 part (iii) in [2]. Received: 9 January 2006     

Dissipative dynamical systems Part II: Linear systems with quadratic supply rates

This paper presents the theory of dissipative systems in the context of finite dimensional stationary linear systems with quadratic supply rates. A necessary and sufficient frequency domain condition for dissipativeness is derived. This is followed by the evaluation of the available storage and the required supply and of a time-domain criterion for dissipativeness involving certain matrix inequalities. The quadratic storage functions and the dissipation functions are then examined. The discussion then turns to reciprocal systems and it is shown that external reciprocity and dissipativeness imply the existence of a state space realization which is also internally reciprocal and dissipative. The paper proceeds with an examination of reversible systems and of relaxation systems. In particular, it is shown how a unique internal storage function may be defined for relaxation systems. These results are applied to the synthesis of electrical networks and the theory of linear viscoelastic materials.     

Oxygen evolution on La0.5Ba0.5CoO3: Transient measurements

The recovery behavior of an aged La_0.5Ba_0.5CoO₃ electrode after interrupting a cathodic discharge current (forced decay, all starting from a high prepolarized state) at a still positive overpotential of 150 mV is discussed. It was found that the potential rises again after interrupting the cathodic current. This rise in potential decreases with decreasing cathodic currents when the electrodes are stabilized at the same starting overpotential before applying the cathodic current. The rise in potential also decreases with decreasing starting overpotential for the same cathodic discharge current. From these measurements it was concluded that higher oxides are present to a certain depth in the oxide layer at high positive overpotentials.Open-circuit decay measurements with different starting overpotentials were performed, all showing logarithmic slopes of ～ 50 mV/dec. The decay rates increased for lower starying overpotentials. Impedances were measured during a decay, from which effective capacitances were calculated. For a given overpotential, the capacitances during a decay were practically constant in the overpotential range from 220 to 150 mV for a given staring overpontential. But for higher starting overpotentials the capacitances were found to be higher. These effects are explained by a change in effective surface area for different starting overpotentials caused by the above-mentioned higher oxides blocking the surface.