Novel Compact and High Selectivity Dual-band BPF with Wide Stopband

A novel type of compact and high selectivity dual-band bandpass filter (BPF) incorporating a dual-mode defected ground structure resonator (DDGSR) and a dual-mode open-stub loaded stepped impedance resonator (DOLSIR) is proposed in this paper. Utilizing capacitive source-load coupling and the intrinsic characteristics of the two types of dual-mode resonators, compact dual-band BPF with multi transmission zeros near the passband edges as well as a wide stopband which can be used to achieve high selectivity is realized. An experimental dual-band BPF located at 2.4 and 3.2 GHz was designed and fabricated. The validity of the design approach is verified by good agreement between simulated and measurement results

Evolution of electromagnetic and Dirac perturbations around a black hole in Horava gravity

The evolution of electromagnetic and Dirac perturbations in the spacetime geometry of Kehagias-Sfetsos(KS) black hole in the deformed Horava-Lifshitz(HL) gravity is investigated and the associated quasinormal modes are evaluated using time domain integration and WKB methods. We find a considerable deviation in the nature of field evolution in HL theory from that in the Schwarzschild spacetime and QNMs region extends over a longer time in HL theory before the power-law tail decay begins. The dependence of the field evolution on the HL parameter $\alpha$ are studied. In the time domain picture we find that the length of QNM region increases with $\alpha$. But the late time decay of field follows the same power-law tail behavior as in the case of Schwarzschild black hole.Comment: The article was fully rewritten, references added, to appear in MPL

Macroporous materials: microfluidic fabrication, functionalization and applications

This article provides an up-to-date highly comprehensive overview (594 references) on the state of the art of the synthesis and design of macroporous materials using microfluidics and their applications in different fields

Optical spectroscopy study of the collapsed tetragonal phase of CaFe2_2(As0.935_{0.935}P0.065_{0.065})2_2 single crystals

We present an optical spectroscopy study on P-doped CaFe$_2$As$_2$ which experiences a structural phase transition from tetragonal to collapsed tetragonal (cT) phase near 75 K. The measurement reveals a sudden reduction of low frequency spectral weight and emergence of a new feature near 3200 \cm (0.4 eV) in optical conductivity across the transition, indicating an abrupt reconstruction of band structure. The appearance of new feature is related to the interband transition arising from the sinking of hole bands near $\Gamma$ point below Fermi level in the cT phase, as expected from the density function theory calculations in combination with the dynamical mean field theory. However, the reduction of Drude spectral weight is at variance with those calculations. The measurement also indicates an absence of the abnormal spectral weight transfer at high energy (near 0.5-0.7 eV) in the cT phase, suggesting a suppression of electron correlation effect.Comment: 6 pages, 4 figure

Topological Quantum Field Theory and Seiberg-Witten Monopoles

A topological quantum field theory is introduced which reproduces the Seiberg-Witten invariants of four-manifolds. Dimensional reduction of this topological field theory leads to a new one in three dimensions. Its partition function yields a three-manifold invariant, which can be regarded as the Seiberg-Witten version of Casson's invariant. A Geometrical interpretation of the three dimensional quantum field theory is also given.Comment: 15 pages, Latex file, no figure