A novel view of plane wave expansion method in photonic crystals

We propose a method derived from the simple plane wave expansion that can easily solve the interface problem between vacuum and a semi-infinite photonic crystal. The method is designed to find the complete set of all the eigenfunctions, propagating or evanescent, of the translation operators $\{{\bf T_R} \}$, at a fixed frequency. With these eigenfunctions and their eigenvalues, the transmitted and reflected waves can be determined. Two kinds of applications are presented for 2D photonic crystals. The first is a selection rule for determine the normal direction of the vacuum-photonic crystal interface to achieve the highest attenuation effect at a gap frequency. The second is to calculate the transmittance and reflectance for a light incident from vacuum to an semi-infinite photonic crystal. As an example we recalculate a system studied previously by K. Sakoda et al. and get results in agreement with theirs

Limits of Binaries That Can Be Characterized by Gravitational Microlensing

Due to the high efficiency of planet detections, current microlensing planet searches focus on high-magnification events. High-magnification events are sensitive to remote binary companions as well and thus a sample of wide-separation binaries are expected to be collected as a byproduct. In this paper, we show that characterizing binaries for a portion of this sample will be difficult due to the degeneracy of the binary-lensing parameters. This degeneracy arises because the perturbation induced by the binary companion is well approximated by the Chang-Refsdal lensing for binaries with separations greater than a certain limit. For binaries composed of equal mass lenses, we find that the lens binarity can be noticed up to the separations of $\sim 60$ times of the Einstein radius corresponding to the mass of each lens. Among these binaries, however, we find that the lensing parameters can be determined only for a portion of binaries with separations less than $\sim 20$ times of the Einstein radius.Comment: 5 pages, 3 figures, 1 tabl

Microlensing Detections of Planets in Binary Stellar Systems

We demonstrate that microlensing can be used for detecting planets in binary stellar systems. This is possible because in the geometry of planetary binary systems where the planet orbits one of the binary component and the other binary star is located at a large distance, both planet and secondary companion produce perturbations at a common region around the planet-hosting binary star and thus the signatures of both planet and binary companion can be detected in the light curves of high-magnification lensing events. We find that identifying planets in binary systems is optimized when the secondary is located in a certain range which depends on the type of the planet. The proposed method can detect planets with masses down to one tenth of the Jupiter mass in binaries with separations <~ 100 AU. These ranges of planet mass and binary separation are not covered by other methods and thus microlensing would be able to make the planetary binary sample richer.Comment: 5 pages, two figures in JPG forma

Attenuation of sound in lined ducts

September 1974Includes bibliographical references (page 264)Extensive computations have been carried out of the attenuation characteristics of resonator and porous type duct liners in rectangular and circular ducts. First the frequency dependence of the attenuation constant and the phase velocity of the fundamental duct mode are obtained for a large number of duct and liner parameters. Then, assuming that the fundamental mode is dominant in the lined duct element, the octave band transmission losses have been computed. The effect of the shape of the input spectrum is discussed and shown explicitly for three different spectra, namely, a "flat" spectrum and spectra with slopes of + 6 dB per octave and - 6 dB per octave, respectively. Finally the effect of the length of the duct liner on the octave band transmission loss has been computed. It is found that the octave band transmission loss does not increase linearly with the length of the duct liner, particularly in regions where the attenuation varies strongly with frequency.This research was carried out in the Gas Turbine Laboratory, M.I.T., supported by the Office of Noise Abatement, Department of Transportation, under Grant DOT-OS-3001

Attenuation of sound in lined circular ducts

April 1975This is an addendum to Gas Turbine Laboratory Report No. 119. --PrefaceIn the previous report, we have used approximate expressions for the wall impedance for the discussion of sound attenuation in lined circular ducts. For instance, Eq. (2.5) has been used for the wall impedance of a circular duct lined with a resonator with a resistive screen, and Eq. (2.8) for a circular duct lined with a porous material. If the ratio of the duct radius to the liner thickness (D/L) is large and the sound frequency is large, the impedance given in Eq. (2.5) or Eq. (2.8) is a good approximation for a lined circular duct. However, when either one of these conditions is not fulfilled, the radial spread of the wave in the liner imposes some effects on the sound attenuation, whereas no wave spreading takes place in the liner of a rectangular duct. In this addendum we derive expressions for the wall impedance of lined circular ducts, accounting for the cylindrical spreading of the waves within the liner. The assumption of a locally reacting surface is still made. On the basis of the impedance thus obtained, the attenuation characteristics of a circular lined duct are computed for a wide range of parameters.This research was carried out in the Gas Turbine Laboratory, M.I.T., supported by the Office of Noise Abatement, Department of Transportation, under Grant DOT-OS-3001

Shareholder Litigation Rights and Corporate Acquisitions

We examine the effect of shareholder litigation rights on managers’ acquisition decisions. Our experimental design exploits a U.S. Ninth Circuit Court of Appeals ruling on July 2, 1999 that resulted in a reduction in shareholder class actions. We find that, since the ruling, firms in Ninth Circuit states acquire larger targets. Furthermore, acquirers’ returns are lower in these states, especially for those with weaker corporate governance. Further analysis shows that value destruction is the result of managers’ freedom to conduct empire-building acquisitions using overvalued equity. Overall, our findings indicate the importance of shareholder litigation as an external governance mechanism

Partially composite two-Higgs doublet model

In the extra dimensional scenarios with gauge fields in the bulk, the Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type attractive four-fermion interactions, which can break electroweak symmetry dynamically with accompanying composite Higgs fields. We consider a possibility that electroweak symmetry breaking (EWSB) is triggered by both a fundamental Higgs and a composite Higgs arising in a dynamical symmetry breaking mechanism induced by a new strong dynamics. The resulting Higgs sector is a partially composite two-Higgs doublet model with specific boundary conditions on the coupling and mass parameters originating at a compositeness scale $\Lambda$. The phenomenology of this model is discussed including the collider phenomenology at LHC and ILC.Comment: 20 pages, 7 figure

Patterns of Interactions in Complex Social Networks Based on Coloured Motifs Analysis

Coloured network motifs are small subgraphs that enable to discover and interpret the patterns of interaction within the complex networks. The analysis of three-nodes motifs where the colour of the node reflects its high – white node or low – black node centrality in the social network is presented in the paper. The importance of the vertices is assessed by utilizing two measures: degree prestige and degree centrality. The distribution of motifs in these two cases is compared to mine the interconnection patterns between nodes. The analysis is performed on the social network derived from email communication

Structural and Functional Analysis of a β2-Adrenergic Receptor Complex with GRK5.

The phosphorylation of agonist-occupied G-protein-coupled receptors (GPCRs) by GPCR kinases (GRKs) functions to turn off G-protein signaling and turn on arrestin-mediated signaling. While a structural understanding of GPCR/G-protein and GPCR/arrestin complexes has emerged in recent years, the molecular architecture of a GPCR/GRK complex remains poorly defined. We used a comprehensive integrated approach of cross-linking, hydrogen-deuterium exchange mass spectrometry (MS), electron microscopy, mutagenesis, molecular dynamics simulations, and computational docking to analyze GRK5 interaction with the β2-adrenergic receptor (β2AR). These studies revealed a dynamic mechanism of complex formation that involves large conformational changes in the GRK5 RH/catalytic domain interface upon receptor binding. These changes facilitate contacts between intracellular loops 2 and 3 and the C terminus of the β2AR with the GRK5 RH bundle subdomain, membrane-binding surface, and kinase catalytic cleft, respectively. These studies significantly contribute to our understanding of the mechanism by which GRKs regulate the function of activated GPCRs. PAPERCLIP

Radiological Significance of Ligamentum Flavum Hypertrophy in the Occurrence of Redundant Nerve Roots of Central Lumbar Spinal Stenosis

Objective: There were previous reports of redundant nerve roots (RNRs) focused on their clinical significance and pathogenesis. In this study, we investigated the significant radiologic findings that correlate with RNRs occurrence. These relations would provide an advanced clue for clinical significance and pathogenesis of RNRs. Methods: Retrospective research was performed with data from 126 patients who underwent surgery for central lumbar spinal stenosis (LSS). Finally, 106 patients with common denominators (inter-observer accuracy : 84%) were included on this study. We divided the patients into two groups by MRI, patients with RNRs and those with no RNRs (NRNRs). Comparative analyses were performed with clinical and radiologic parameters. Results: RNRs were found in 45 patients (42%) with central LSS. There were no statistically significant differences between the two groups in severity of symptoms. On the other hand, we found statistically significant differences in duration of symptom and number of level included (p<0.05). In the maximal stenotic level, ligamentum flavum (LF) thickness, LF cross-sectional area (CSA), dural sac CSA, and segmental angulation are significantly different in RNRs group compared to NRNRs group (p<0.05). Conclusion: RNRs patients showed clinically longer duration of symptoms and multiple levels included. We also confirmed that wide segmental angulation and LF hypertrophy play a major role of the development of RNRs in central LSS. Together, our results suggest that wide motion in long period contribute to LF hypertrophy, and it might be the key factor of RNRs formation in central LSS