Weiss oscillations in the electronic structure of modulated graphene

We present a theoretical study of the electronic structure of modulated graphene in the presence of a perpendicular magnetic field. The density of states and the bandwidth for the Dirac electrons in this system are determined. The appearance of unusual Weiss oscillations in the bandwidth and density of states is the main focus of this work.Comment: 8 pages, 2 figures, accepted in J. Phys.: Conden. mat

Icmapen: an icmetric based security framework for sleep apnea monitoring

Smart devices are becoming increasingly powerful which is why they are being used for point of care health services. Wearable devices can be purchased which allow continuous monitoring of a wearers vital signs. The data is generated, processed and stored remotely where it can be readily accessible to health professionals. Recent attacks on healthcare systems and health data shows that the systems are insecure and that security is a major hurdle in their wide adoption. Conventional cryptographic systems rely on stored keys for the provision of security. The stored keys can be captured in many ways which leads to the system being exposed. The ICMetric technology remedies this by eliminating the need for stored keys. Thus, the ICMetric technology functions as a key theft deterrent and as a basis for cryptographic services. This paper studies the design and implementation of an ICMetric based health monitoring system for people diagnosed with sleep apnea. The proposed system provides key generation, authentication and confidentiality by using the novel ICMetric technology. The proposed scheme is constituent of a cloud computing component which enables remote monitoring and data storage for access by health professionals.  This paper studies the performance of the proposed schemes by studying the running time. The security of the scheme has also been studied to show that the system provides high levels of security without resource compromise.Keywords: ICMetric; Sleep apnea; Cloud computing; Authentication; Confidentialit

A secure cloud framework for ICMetric based IoT health devices.

Wearable devices are an important part of internet of things (IoT)with many applications in healthcare. Prevalent security concerns create a compelling case for a renewed approach by incorporating the ICMetric technology in IoT healthcare. The ICMetric technology is a novel security approach and uses the features of a device to form the basis of cryptographic services like key generation, authentication and admission control. Cryptographic systems designed using ICMetric technology use unique measurable device features to form a root of trust. This paper uses the MEMS bias in a body wearable Shimmer sensor to create a device ICMetric. The ICMetric identity is used to generate cryptographic key to perform encryption and decryption of patients data which is being communicated to health professionals. The cloud based component of the proposed framework provides much needed distributed data processing and availability. The proposed schemes have been simulated and tested for conformance to high levels of security and performance

Multi-parameter approach to R-parity violating SUSY couplings

We introduce and implement a new, extended approach to placing bounds on trilinear R-parity violating couplings. We focus on a limited set of leptonic and semi-leptonic processes involving neutrinos, combining multidimensional plotting and cross-checking constraints from different experiments. This allows us to explore new regions of parameter space and to relax a number of bounds given in the literature. We look for qualitatively different results compared to those obtained previously using the assumption that a single coupling dominates the R-parity violating contributions to a process (SCD). By combining results from several experiments, we identify regions in parameter space where two or more parameters approach their maximally allowed values. In the same vein, we show a circumstance where consistency between independent bounds on the same combinations of trilinear coupling parameters implies mass constraints among slepton or squark masses. Though our new bounds are in most cases weaker than the SCD bounds, the largest deviations we find on individual parameters are factors of two, thus indicating that a conservative, order of magnitude bound on an individual coupling is reliably estimated by making the SCD assumption.Comment: 30 pages, 8 figures, 2 tables. Typos fixed, two references added and references updated. Eq. (41) removed, Eq. (40) and text modified. Published versio

Ab Initio Evidence for the Formation of Impurity d(3z^2-r^2) Holes in Doped La_{2-x}Sr_xCuO_4

Using the spin unrestricted Becke-3-Lee-Yang-Parr density functional, we computed the electronic structure of explicitly doped La_{2-x}Sr_xCuO_4 (x = 0.125, 0.25, and 0.5). At each doping level, an impurity hole band is formed within the undoped insulating gap. This band is well-localized to CuO_6 octahedra adjacent to the Sr impurities. The nature of the impurity hole is A_{1g} in symmetry, formed primarily from the z^2 orbital on the Cu and p_z orbitals on the apical O's. There is a strong triplet coupling of this hole with the intrinsic B_{1g} Cu x^2-y^2/O1 p_{sigma} hole on the same site. Optimization of the c coordinate of the apical O's in the doped CuO_6 octahedron lead to an asymmetric anti-Jahn-Teller distortion of the O2 atoms toward the central Cu. In particular, the O2 atom between the Cu and Sr is displaced 0.26 A while the O2 atom between the Cu and La is displaced 0.10 A. Contrary to expectations, investigation of a 0.1 A enhanced Jahn-Teller distortion of this octahedron does not force formation of an x^2-y^2 hole, but instead leads to migration of the z^2 hole to the four other CuO_6 octahedra surrounding the Sr impurity. This latter observation offers a simple explanation for the bifurcation of the Sr-O2 distance revealed in x-ray absorption fine structure data.Comment: Submitted to Phys. Rev. B. See http://www.firstprinciples.com for more informatio

Commissioning Existing Buildings: A Program Perspective

Since September 2002, the Oakland Energy Partnership's Large Commercial Building Tune-Up Program has recruited managers and operators of existing large commercial buildings in the City of Oakland for program participation. The Tune-Up Program is an aggressive effort to obtain 16.7 GWh in energy savings in over 10 Mft2 in office, institutional, healthcare, hotel, educational, and retail buildings. Sponsored under the California Public Utility Commission's 2002 Local Program initiative, the Tune-Up program provides retro commissioning (r-Cx) teams to help building owners and operators thoroughly investigate the operations and performance of their existing building systems, identify measures that improve energy performance, assist with measure installation and verification, and provide documentation to operators on optimum system performance. Great importance has been placed on the initial assessment of each building, in order to answer important questions from the program's and owner's perspectives. These issues include: condition of building's systems and equipment, amount of savings potential, skill sets of r-Cx teams, assurance that measures will be installed, persistence of installed measures. This paper describes how the program recruits buildings, assesses the potential for savings, and assigns engineering teams. The type and size of buildings, their HVAC and lighting configurations, common r-Cx measures found, and their savings are described Results for each building are described, and the program's cost-effectiveness is reviewed. Currently, six buildings totaling 2.8 million square feet have been recruited, for an expected savings of approximately 2.4 GWh. This is 14% toward our program goal

Electronic and Optical Properties of Aluminum Oxide Before and After Surface Reduction by Ar+ Bombardment

The electronic and optical properties of a-Al2O3 after induced by 3-keV Ar+ sputtering  have been studied quantitatively by use of reflection electron energy loss spectroscopy (REELS) spectra. The band gap values of a-Al2O3 was determined from the onset values of the energy loss spectrum to the background level of REELS spectra as a function of time Ar+ bombardment. The bandgap changes from 8.4 eV before sputtering to 6.2 eV after 4 minutes of sputtering.The optical properties of α-Al2O3 thin films have been determined by comparing the experimental cross section obtained from reflection electron energy loss spectroscopy with the theoretical inelastic scattering cross section, deduced from the simulated energy loss function (ELF) by using QUEELS-ε(k)-REELS software. The peak assignments are based on ELF and compared with reported data on the electronic structure of α-Al2O3 obtained using different techniques. The results demonstrate that the electronic and optical properties before and after surface reduction will provide further understanding in the fundamental properties of α-Al2O3 which will be useful in the design, modeling and analysis of devices applications performance.Received: 18 November 2013; Revised:12 June 2014; Accepted: 25 June 2014

Deviation Value of CTDI100 for Phantom Regional Territories by Using Chamber Ionization Detector

Determining CTDI100 and CTDI100 deviation values at the central and side region of the phantom by using head protocols have been performed as CT-Scan test parameters. Methods and materials of Axial CT scanning are used at the head phantom that contains a chamber ionization detector. The head phantom is a PMMA given a hole in the middle of the phantom, the top side (clockwise 12), right side (clockwise 3), bottom side (clockwise 6) and left side (clockwise 9). Head phantom has 16 cm of diameter and 15 cm of length. In this study, to determine the comparison of CTDI100 values at the phantom center against all sides phantom against CTDI100 factory baseline values. The result shows that the comparison of CTDI100 at the top side is highest value about 26.87 mGy and the smallest at the bottom side about 25,15 mGy. On the right side is 26.12 mGy, on the left side is 25.92 mGy, and at the center is 25.84 mGy. For smaller deviations at the center is 9.82% compared to other phantom sides, the highest deviation value at the bottom side is 12.83% while at the top side is 12.05%, at right side is 11.65% and at the left side is 11.72 %, but this deviation value is still within the tolerance limit of ≤ 20%

Determination of the Half-Value Layer by Using Filter Aluminum Sheets for Digital Mammography

A method of determining the half-value layers (HVL) with or without using an aluminum (Al) filter sheet for digital mammography has been developed. HVL measurements using a single exposure method are performed without the addition of an aluminium filter. This study was conducted to evaluate the accuracy of measurements of HVL values in a single exposure method using a RaySave ion space detector. a standard method with a variation in aluminium filter thickness from 0.110 to 0.980 mm. The HVL measurement values were performed with the distance between the focus of the detector 60.5 cm, and the current 80 mAs at a voltage of 23 kVp, 25 kVp, 27 kVp, 29 kVp and 32 kVp. The HVL value is determined by using the interpolation formula. The results showed that the HVL value using aluminium filter was 0.03 mm higher than the standard method by using multiple exposures for the same thickness of the aluminium filter

Electronic and Optical Properties of Aluminum Oxide Before and After Surface Reduction by Ar+ Bombardment

The electronic and optical properties of a-Al2O3 after induced by 3-keV Ar+ sputtering have been studied quantitatively by use of reflection electron energy loss spectroscopy (REELS) spectra. The band gap values of a-Al2O3 was determined from the onset values of the energy loss spectrum to the background level of REELS spectra as a function of time Ar+ bombardment. The bandgap changes from 8.4 eV before sputtering to 6.2 eV after 4 minutes of sputtering.The optical properties of α-Al2O3 thin films have been determined by comparing the experimental cross section obtained from reflection electron energy loss spectroscopy with the theoretical inelastic scattering cross section, deduced from the simulated energy loss function (ELF) by using QUEELS-ε(k)-REELS software. The peak assignments are based on ELF and compared with reported data on the electronic structure of α-Al2O3 obtained using different techniques. The results demonstrate that the electronic and optical properties before and after surface reduction will provide further understanding in the fundamental properties of α-Al2O3 which will be useful in the design, modeling and analysis of devices applications performance.Received: 18 November 2013; Revised:12 June 2014; Accepted: 25 June 201