Electronic structure of In1-xMnxAs studied by photoemission spectroscopy: Comparison with Ga1-xMnxAs

We have investigated the electronic structure of the p-type diluted magnetic semiconductor In1-xMnxAs by photoemission spectroscopy. The Mn 3d partial density of states is found to be basically similar to that of Ga1-xMnxAs. However, the impurity-band-like states near the top of the valence band have not been observed by angle-resolved photoemission spectroscopy unlike Ga1-xMnxAs. This difference would explain the difference in transport, magnetic and optical properties of In1-xMnxAs and Ga1-xMnxAs. The different electronic structures are attributed to the weaker Mn 3d-As 4p hybridization in In1-xMnxAs than in Ga1-xMnxAs.

Understanding the building-up process of three dimensional open-framework metal phosphates: Acid degradation of the 3D structures to lower dimensional structures

Acid degradation of 3D zinc phosphates primarily yields a one-dimensional ladder compound, an observation that is significant considering that the latter forms 3D structures on heating in water.

Band Structures of Bilayer Graphene Superlattices

We formulate a low energy effective Hamiltonian to study superlattices in bilayer graphene (BLG) using a minimal model which supports quadratic band touching points. We show that a one dimensional (1D) periodic modulation of the chemical potential or the electric field perpendicular to the layers leads to the generation of zero-energy anisotropic massless Dirac fermions and finite energy Dirac points with tunable velocities. The electric field superlattice maps onto a coupled chain model comprised of ``topological'' edge modes. 2D superlattice modulations are shown to lead to gaps on the mini-Brillouin zone boundary but do not, for certain symmetries, gap out the quadratic band touching point. Such potential variations, induced by impurities and rippling in biased BLG, could lead to subgap modes which are argued to be relevant to understanding transport measurements.

Wavelet Transform Codec for Fast Retrieval of Slices of 3D Objects

We propose a method to encode a 3D magnetic resonance image data and a decoder in such way that fast access to any 2D image is possible by decoding only the corresponding information from each subband image and thus provides minimum decoding time. This will be of immense use for medical community, because most of the PET and MRI data are volumetric data. Preprocessing is carried out at every level before wavelet transformation, to enable easier identification of coefficients from each subband image. Inclusion of special characters in the bit stream facilitates access to corresponding information from the encoded data. Results are taken by performing Daub4 along x (row), y (column) direction and Haar along z (slice) direction. Comparable results are achieved with the existing technique. In addition to that decoding time is reduced by 1.98 times. Arithmetic coding is used to encode corresponding information independently

Study of band offsets in InN/Ge heterojunctions

InN layers were directly grown on Ge substrate by plasma-assisted molecular beam epitaxy (PAMBE). The valence band offset (VBO) of wurtzite InN/Ge heterojunction is determined by X-ray photoemission spectroscopy (XPS). The valence band of Ge is found to be 0.18 +/- 0.04 eV above that of InN and a type-II heterojunction with a conduction band offset (CBO) of similar to 0.16 eV is found. The accurate determination of the VBO and CBO is important for the design of InN/Ge based electronic devices. (C) 2011 Elsevier B.A. All rights reserved.

An Efficient and Optimized Bluetooth Scheduling Algorithm for Scatternets

Bluetooth is a short-range radio technology operating in the unlicensed industrial-scientific-medical (ISM) band at 2.45 GHz. A scatternet is established by linking several piconets together in ad hoc fashion to yield a global wireless ad hoc network. This paper proposes a polling policy that aims to achieve increased system throughput and reduced packet delays while providing reasonably good fairness among all traffic flows in a Bluetooth Scatternet. Experimental results from our proposed algorithm show performance improvements over a well known existing algorithm.

LTCC ultra wide band filter

This article presents the analysis of ultra wide band (UWB) filler designed using a symmetrical three parallel coupled line resonator in low temperature co-fired ceramic (LTCC) medium: The ground plane with an aperture incorporated in it improves the coupling. Based on circuit models, the designed UWB filter has been analyzed, and the results have been confirmed by experiments. The filter has been realized with Dupont LTCC tape DuPont 951 (that has dielectric constant of 7.8). Maximum insertion loss of the experimental filter is 1.5 dB. The group variation over the pass band of the filter is within 0.2 us. Dimensions of the experimental LTCC filter are 20 x 10 x 0.72 mm. (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2580-2583,2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26311

3D Image Reconstruction From Truncated Helical Cone Beam Projection Data - A Linear Prediction Approach

With the introduction of 2D flat-panel X-ray detectors, 3D image reconstruction using helical cone-beam tomography is fast replacing the conventional 2D reconstruction techniques. In 3D image reconstruction, the source orbit or scanning geometry should satisfy the data sufficiency or completeness condition for exact reconstruction. The helical scan geometry satisfies this condition and hence can give exact reconstruction. The theoretically exact helical cone-beam reconstruction algorithm proposed by Katsevich is a breakthrough and has attracted interest in the 3D reconstruction using helical cone-beam Computed Tomography.In many practical situations, the available projection data is incomplete. One such case is where the detector plane does not completely cover the full extent of the object being imaged in lateral direction resulting in truncated projections. This result in artifacts that mask small features near to the periphery of the ROI when reconstructed using the convolution back projection (CBP) method assuming that the projection data is complete. A number of techniques exist which deal with completion of missing data followed by the CBP reconstruction. In 2D, linear prediction (LP)extrapolation has been shown to be efficient for data completion, involving minimal assumptions on the nature of the data, producing smooth extensions of the missing projection data.In this paper, we propose to extend the LP approach for extrapolating helical cone beam truncated data. The projection on the multi row flat panel detectors has missing columns towards either ends in the lateral direction in truncated data situation. The available data from each detector row is modeled using a linear predictor. The available data is extrapolated and this completed projection data is backprojected using the Katsevich algorithm. Simulation results show the efficacy of the proposed method.

A Profilometric Approach to 3D Face Reconstruction and Its Application to Face Recognition

3D Face Recognition is an active area of research for past several years. For a 3D face recognition system one would like to have an accurate as well as low cost setup for constructing 3D face model. In this paper, we use Profilometry approach to obtain a 3D face model.This method gives a low cost solution to the problem of acquiring 3D data and the 3D face models generated by this method are sufficiently accurate. We also develop an algorithm that can use the 3D face model generated by the above method for the recognition purpose.