Minimum Step Research Articles

A 12.8-ns-Latency DDFS MMIC With Frequency, Phase, and Amplitude Modulations in 65-nm CMOS

This paper describes a digital-mapping direct digital frequency synthesizer having a tuning and amplitude resolutions of 24 and 10 bits, respectively. This Si-CMOS-monolithic microwave-integrated circuit (MMIC) is the first solution supporting a sampling rate of 7 GS/s with frequency modulation, phase modulation (PM), and amplitude modulation (AM) in the digital domain. It includes a 14 bits pipelined ripple-carry phase adder and a 10-bits high-speed amplitude multiplier. The minimum frequency, phase, and amplitude steps are 417.2 Hz, 0.022°, and 1.17 mV, respectively. A proof-of-concept chip with an active area of 0.23 mm2 was fabricated in a 1P9M 65-nm CMOS process and characterized in low-profile quad flat package (LQFP). The worst case wideband/narrowband spurious-free dynamic range is 32/42 dBc. This system consumes 85.9 mW/(GS/s) from a 1.2-V power supply when the PM/AM are enabled, resulting in an figure of merit (FoM) of 469.6 GS/ $\text {s}\cdot {2}^{(\mathrm {SFDR}/6)}$ /W. The absolute single sideband phase noise at 100 KHz offset from the carrier was better than −125 dBc/Hz in all the evaluated frequencies. A latency of 12.86 ns was measured when operating at 7 GS/s.

Penyelesaian Terus Persamaan Pembezaan Biasa Peringkat Tiga menggunakan Kaedah Blok Hibrid Kolokasi Diperbaiki

The improved block hybrid collocation method (KBHK(B)) with two off-step points and four collocation points is proposed for the direct solution of general third order ordinary differential equations. Modification is done by adding first derivative of third order function into the general form of block hybrid collocation method to yield KBHK(B). Both main and additional methods are derived via interpolation (power series function) and collocation of the basic polynomial. An improved block method is derived to provide the approximation at five points concurrently. Zero stability, consistency, convergence and absolute stability region of KBHK(B) are investigated. Some numerical examples with exact solution are tested to illustrate the efficiency of the method. KBHK(B) is compared by other block hibrid collocation method in term of global error and step number. It is shown that KBHK(B) generates minimum global error with minimum step number.

Coplanar Intermodulation Reference Generator Using Substrate Integrated Waveguide With Integrated Artificial Nonlinear Dipole

An intermodulation (IM) generator based on substrate integrated waveguide (SIW) is demonstrated. This generator has maximal 80 dB dynamic range with a size that is smaller than 65 mm × 40 mm × 1.5 mm. A biased Schottky diode is mounted onto the slotted plane of SIW and it consists of a nonlinear dipole to radiate nonlinear signal to the carrier domain and serve as reference signal. A polarized slot helps focus the linear carrier wave onto the diode and construct a bias-controlled IM distortion. The experiment proves that this device can generate the IM3 reference ranges from -112 to -32 dBm at 2 × 43 dBm, while its minimum step can reach lesser than 0.5 dB. This proposed device can serve as tunable IM standards in PIM test and calibrate the commercial PIM tester.

Application of a Log Likelihood Object In GARCH with T-distributed errors and EGARCH With Generalised Error Distribution Model of the Spot AUD/USD Exchange Rate Volatility.

In this article, we have tested the volatility of the returns of the spot exchange rate of AUD/USD for changing conditional variances by using a log likelihood model. Generalized autoregressive conditional heteroskedastic models, (GARCH) with t-distributed errors, and exponential generalized autoregressive conditional heteroskedastic model, (EGARCH) with generalised error distribution take into account the non-linearity that arises in the financial time series. The aim is to compare and select the maximum value of the log likelihood estimation of the AUD/USD spot exchange rate. The log likelihood model take into account autoregressive, (AR), moving average, (MA), and monthly seasonal moving average, (SMA) factors that could better explain volatility clusters. We have selected the model with the best forecasting ability in terms of the lowest value of the Akaike information criterion, the Schwarz criterion, the Hannan – Quinn criterion. The best model will help the arbitrageurs to better craft their investment strategy in terms of holding, buying or selling portfolios of foreign currencies. The software that we have used is EViews 6. We have concluded that the best fit model is the GRACH model with a t-distribution, as it has the maximum log likelihood estimation of -500.354. The average log likelihood is -1.81. The Akaike information criterion, the Schwarz criterion and the Hannan – Quinn criterion have the lowest error estimates. Their values are 3.60, 3.56 and 3.59 respectively. In terms of gradients at the estimated parameters, we have found that there are outlier values and significant fluctuations at the various observations of the coefficients vectors, C(1), C(2), and C(3) of the gradients. Finally, the analytic derivatives were calculated based on the specified values. The real and minimum step sizes are identical for all coefficients vectors and very close to zero. We have used one-sided numeric derivative. The data that we have used are monthly returns starting from 01/01/1990 to 01/01/2013, which total to 276 observations. The total dataset includes 277 observations. The data was obtained from the Federal Reserve Statistical Release Department and the symbol of the series is H.10.

Application of a Log Likelihood Object of An ARMA Model of Well – Known Closed – End Funds of Major Investment Banks.

In this article, we have applied an autoregressive moving average, ARMA(2,2) model of order AR(1), AR(2), MA(1), MA(2) and SMA(12) to test the natural logarithmic monthly market returns of the of the closed – end funds of major investment banks such as Van Kampen income trust, Aberden Asia Pacific income fund, Credit Suisse asset management income, Scudder high income and Templeton global income. The purpose of this article is to eliminate the seasonality, to compare and select the maximum value of the log likelihood estimation of the different closed-end funds. We have selected the model with the best forecasting ability in terms of the lowest value of the Akaike information criterion, the Schwarz criterion, the Hannan – Quinn criterion. The software that we have used is EViews 6. We have found that the natural logarithmic monthly market price returns of all closed-end funds are a stationary series. We have concluded that the best fit model is Scudder high income, (LNMPSHI), closed-end fund as it has the maximum log likelihood value of -123.16 and the Akaike information criterion, the Schwarz criterion, and the Hannan – Quinn criterion are 1.65, 1.55 an 1.61 respectively. In terms of gradients at the estimated parameters, we have found that there are outlier values and significant fluctuations at the various observations of the coefficients vectors, C(1), C(2), C(3), C(4) and C(5) of the gradients. The gradients of the log likelihood function have been computed at the estimated parameters and the unsuccessful estimation are displayed through the outliers of the peak of the graph of the four closed-end funds. Credit Suisse asset management income, (LNMPCS), closed-end fund displayed less outlier values and not significant fluctuations at the various observations of the coefficients vectors, C(1), C(2), C(3), C(4) and C(5) of the gradients. Finally, the analytic derivatives were calculated based on the specified values. The real and minimum step sizes are identical for all coefficients vectors and very close to zero. We have used one-sided numeric derivative. The whole dataset is from 31/01/1990 to 31/12/2001. The total observations are 144 and the logarithmic monthly market returns observations are 143.The data was obtained from Thomson Financial Investment View database.

Impact of the hardened floating-point cores on HIL technology

The Hardware-In-the-Loop (HIL) technique is increasingly used for testing power electronics. FPGAs (Field-Programmable Gate Array) are becoming usual in this kind of emulation due to their acceleration capabilities. But even using FPGAs, it has not been possible to reach real time simulations when small integration steps are necessary (around 100ns or lower) if floating-point representation is used. Fixed-point has been the solution, but at a high design effort cost. With the release of FPGAs with HFP (Hardened Floating-Point) cores – dedicated floating-point blocks implemented in silicon –, the minimum achievable simulation step decreases significantly. This paper presents a comparison between HFP cores, floating-point in programmable logic and fixed-point for HIL models. Results show that both HFP-based and fixed-point arithmetic achieve a simulation step around 10ns for a full-bridge converter model. A comparison regarding resolution and accuracy is also presented, because acceleration is not the only issue when decreasing the integration step. Numerical resolution also plays an important role, and 32-bit floating-point representation finds a double barrier: acceleration marked by technology, and numerical resolution. Both are explored in this paper.

Minimum Energy Efficiency Standards and steps to improve energy inefficient properties

The much-anticipated Minimum Energy Efficiency Standards (MEES) came into force on 1st April, 2018. This paper looks at the implications the regulations may have on the property market and whether the regulations can be the catalyst for improved energy efficiency that so many have hoped. While it was intended that the regulations would ensure that poor performing properties are brought up to standards, the unintended benefits may be even greater. The regulations will impact many aspects of the property market including rent reviews, lease renewals and service charge. The potential benefits to a landlord in having a highly-rated Energy Performance Certificate (EPC) could drive a ‘rush to the top’ as landlords seek to achieve a rating that goes well beyond the minimum requirement set out in the regulations.

Piezoelectric inchworm rotary actuator with high driving torque and self-locking ability

One major obstacle to the development of a piezoelectrically-driven actuator with a large motion range is the requirement to provide a high load capacity and a reliable self-locking capability simultaneously for most applications. In this work, a piezo-driven rotary actuator with a simple and compact structure is designed based on the inchworm principle to realize long-range rotary motion. High driving torque with a self-locking capability at rest is achieved by integral design of the overall structure, in which the distributions and stiffness values of the flexure hinges are carefully designed. A prototype was fabricated and the working performance of the device was tested. The test results demonstrate that the driving torque of the prototype is more than 245 Nmm, with self-locking torque of more than 882 Nmm. In addition, the maximum rotary speed is 26.74 mrad/s at a driving frequency of 180 Hz, and a minimum step rotary angle of 4.79 μrad is obtained at a step driving voltage of 10 V.

Direct nucleic acid analysis of mosquitoes for high fidelity species identification and detection of Wolbachia using a cellphone

Manipulation of natural mosquito populations using the endosymbiotic bacteria Wolbachia is being investigated as a novel strategy to reduce the burden of mosquito-borne viruses. To evaluate the efficacy of these interventions, it will be critical to determine Wolbachia infection frequencies in Aedes aegypti mosquito populations. However, current diagnostic tools are not well-suited to fit this need. Morphological methods cannot identify Wolbachia, immunoassays often suffer from low sensitivity and poor throughput, while PCR and spectroscopy require complex instruments and technical expertise, which restrict their use to centralized laboratories. To address this unmet need, we have used loop-mediated isothermal amplification (LAMP) and oligonucleotide strand displacement (OSD) probes to create a one-pot sample-to-answer nucleic acid diagnostic platform for vector and symbiont surveillance. LAMP-OSD assays can directly amplify target nucleic acids from macerated mosquitoes without requiring nucleic acid purification and yield specific single endpoint yes/no fluorescence signals that are observable to eye or by cellphone camera. We demonstrate cellphone-imaged LAMP-OSD tests for two targets, the Aedes aegypti cytochrome oxidase I (coi) gene and the Wolbachia surface protein (wsp) gene, and show a limit of detection of 4 and 40 target DNA copies, respectively. In a blinded test of 90 field-caught mosquitoes, the coi LAMP-OSD assay demonstrated 98% specificity and 97% sensitivity in identifying Ae. aegypti mosquitoes even after 3 weeks of storage without desiccant at 37°C. Similarly, the wsp LAMP-OSD assay readily identified the wAlbB Wolbachia strain in field-collected Aedes albopictus mosquitoes without generating any false positive signals. Modest technology requirements, minimal execution steps, simple binary readout, and robust accuracy make the LAMP-OSD-to-cellphone assay platform well suited for field vector surveillance in austere or resource-limited conditions.

A Fast Matrix Majorization-Projection Method for Penalized Stress Minimization With Box Constraints

Kruskal's stress minimization, though nonconvex and nonsmooth, has been a major computational model for dissimilarity data in multidimensional scaling. Semidefinite programming (SDP) relaxation (by dropping the rank constraint) would lead to a high number of SDP cone constraints. This has rendered the SDP approach computationally challenging even for problems of small size. In this paper, we reformulate the stress optimization as an Euclidean distance matrix (EDM) optimization with box constraints. A key element in our approach is the conditional positive-semidefinite cone with rank cut. Although nonconvex, this geometric object allows a fast computation of the projection onto it, and it naturally leads to a majorization-minimization algorithm with the minimization step having a closed-form solution. Moreover, we prove that our EDM optimization follows a continuously differentiable path, which greatly facilitated the analysis of the convergence to a stationary point. The superior performance of the proposed algorithm is demonstrated against some of the state-of-the-art solvers in the field of sensor network localization and molecular conformation.

ProPOSE: Direct Exhaustive Protein-Protein Docking with Side Chain Flexibility.

Despite decades of development, protein-protein docking remains a largely unsolved problem. The main difficulties are the immense space spanned by the translational and rotational degrees of freedom and the prediction of the conformational changes of proteins upon binding. FFT is generally the preferred method to exhaustively explore the translation-rotation space at a fine grid resolution, albeit with the trade-off of approximating force fields with correlation functions. This work presents a direct search alternative that samples the states in Cartesian space at the same resolution and computational cost as standard FFT methods. Operating in real space allows the use of standard force field functional forms used in typical non-FFT methods as well as the implementation of strategies for focused exploration of conformational flexibility. Currently, a few misplaced side chains can cause docking programs to fail. This work specifically addresses the problem of side chain rearrangements upon complex formation. Based on the observation that most side chains retain their unbound conformation upon binding, each rigidly docked pose is initially scored ignoring up to a limited number of side chain overlaps which are resolved in subsequent repacking and minimization steps. On test systems where side chains are altered and backbones held in their bound state, this implementation provides significantly better native pose recovery and higher quality (lower RMSD) predictions when compared with five of the most popular docking programs. The method is implemented in the software program ProPOSE (Protein Pose Optimization by Systematic Enumeration).

Dynamic stability of the actin ecosystem.

In cells, actin filaments continuously assemble and disassemble while maintaining an apparently constant network structure. This suggests a perfect balance between dynamic processes. Such behavior, operating far out of equilibrium by the hydrolysis of ATP, is called a dynamic steady state. This dynamic steady state confers a high degree of plasticity to cytoskeleton networks that allows them to adapt and optimize their architecture in response to external changes on short time-scales, thus permitting cells to adjust to their environment. In this Review, we summarize what is known about the cellular actin steady state, and what gaps remain in our understanding of this fundamental dynamic process that balances the different forms of actin organization in a cell. We focus on the minimal steps to achieve a steady state, discuss the potential feedback mechanisms at play to balance this steady state and conclude with an outlook on what is needed to fully understand its molecular nature.

An X-band Bi-Directional Transmit/Receive Module for a Phased Array System in 65-nm CMOS.

We present an X-band bi-directional transmit/receive module (TRM) for a phased array system utilized in radar-based sensor systems. The proposed module, comprising a 6-bit phase shifter, a 6-bit digital step attenuator, and bi-directional gain amplifiers, is fabricated using 65-nm CMOS technology. By constructing passive networks in the phase-shifter and the variable attenuator, the implemented TRM provides amplitude and phase control with 360° phase coverage and 5.625° as the minimum step size while the attenuation range varies from 0 to 31.5 dB with a step size of 0.5 dB. The fabricated T/R module in all of the phase shift states had RMS phase errors of less than 4° and an RMS amplitude error of less than 0.93 dB at 9–11 GHz. The output 1dB gain compression point (OP1dB) of the chip was 5.13 dBm at 10 GHz. The circuit occupies 3.92 × 2.44 mm2 of the chip area and consumes 170 mW of DC power.

Smart spectrophotometric methods based on normalized spectra for simultaneous determination of alogliptin and metformin in their combined tablets

Alogliptin (ALO) and metformin (MET) are coformulated for the treatment of type II diabetes mellitus. ALO is estimated at its λmax 277 nm (0D), while MET was determined accurately by four spectrophotometric methods with minimum manipulation steps based on normalized division spectrum namely; ratio difference, advanced amplitude modulation, first derivative ratio (1DD) and mean centering of the ratio spectra spectrophotometric methods. Linearity was acceptable over the concentration ranges of 5–40 and 2–16 μg/mL for ALO and MET, respectively. Accuracy and precision of the suggested methods were found to be within the acceptable limit. The specificity was inspected by analyzing laboratory prepared mixtures of the above drugs and their pharmaceutical preparation. The results of proposed and reported methods were statistically compared showing no significant difference regarding accuracy and precision. The developed methods could be applied for routine analysis of the cited drugs in quality control laboratories.

Novel Iterative Algorithm for the Solution of Electromagnetic Scattering From Layered Random Rough Surfaces

A robust and accurate iterative algorithm is proposed for the solution of electromagnetic wave scattering from 1-D layered rough surfaces. The forward–backward method (FBM) has been applied extensively for solving electromagnetic scattering from single-layer rough surfaces due to its rapid convergence rate. Nevertheless, the performance of the FBM deteriorates, as it is applied to layered random rough surface problems. The proposed method greatly improves the convergence rate of the FBM by applying a residual minimization step. The computational cost of the minimization step and the forward–backward sweeps is expedited by using the spectral acceleration. In this communication, the proposed algorithm is applied as a solution to the problem of electromagnetic wave scattering from layered rough surfaces. Numerical results are presented to demonstrate the better convergence properties of the proposed method as compared with the standard FBM. In addition, the proposed method is shown to be more robust than the FBM, especially as the distance between interfaces decreases. The computational complexity of the proposed algorithm is also presented and discussed.

In silico design of potentially functional artificial metallo-haloalkane dehalogenase containing catalytic zinc

Artificial metalloenzymes are unique as they combine the good features of homogeneous and enzymatic catalysts, and they can potentially improve some difficult catalytic assays. This study reports a method that can be used to create an artificial metal-binding site prior to proving it to be functional in a wet lab. Haloalkane dehalogenase was grafted into a metal-binding site to form an artificial metallo-haloalkane dehalogenase and was studied for its potential functionalities in silico. Computational protocols regarding dynamic metal docking were studied using native metalloenzymes and functional artificial metalloenzymes. Using YASARA Structure, a simulation box covering template structure was created to be filled with water molecules followed by one mutated water molecule closest to the metal-binding site to metal ion. A simple energy minimization step was subsequently run using an AMBER force field to allow the metal ion to interact with the metal-binding residues. Long molecular dynamic simulation using YASARA Structure was performed to analyze the stability of the metal-binding site and the distance between metal-binding residues. Metal ions fluctuating around 2.0Å across a 20ns simulation indicated a stable metal-binding site. Metal-binding energies were predicted using FoldX, with a native metalloenzyme (carbonic anhydrase) scoring 18.0kcal/mol and the best mutant model (C1a) scoring 16.4kcal/mol. Analysis of the metal-binding site geometry was performed using CheckMyMetal, and all scores for the metalloenzymes and mutant models were in an acceptable range. Like native metalloenzymes, the metal-binding site of C1a was supported by residues in the second coordination shell to maintain a more coordinated metal-binding site. Short-chain multihalogenated alkanes (1,2-dibromoethane and 1,2,3-trichloropropane) were able to dock in the active site of C1a. The halides of the substrate were in contact with both the metal and halide-stabilizing residues, thus indicating a better stabilization of the substrate. The simple catalytic mechanism proposed is that the metal ion interacted with halogen and polarized the carbon-halogen bond, thus making the alpha carbon susceptible to attack by nucleophilic hydroxide. The interaction between halogen in the metal ion and halide-stabilizing residues may help to improve the stabilization of the substrate-enzyme complex and reduce the activation energy. This study reports a modified dynamic metal-docking protocol and validation tests to verify the metal-binding site. These approaches can be applied to design different kinds of artificial metalloenzymes or metal-binding sites.

Harboring Contaminants in Repeatedly Reprocessed Pedicle Screws.

Study Design:It consisted of evaluation of the pedicle screws for presence of residual nonmicrobial contaminants and tabulation of the minimum steps and time required for reprocessing implants as per guidelines and its comparison with actual practice.Objective:An evaluation of the nonmicrobial contaminants prevalent on the pedicle screws used for spine surgery and the underlying practice cause behind the source.Methods:The first component consisted of a random selection of 6 pedicle screws and its assessment using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The second component consisted of review of implant reprocessing guidelines and its applicability.Results:Three types of contaminants were identified: corrosion, saccharide of unknown origin, and soap residue mixed with and were mostly present at the interfaces with low permeability. In addition, manufacturer’s guideline recommends 19 hours of reprocessing, whereas the real-time observation revealed a turnaround time of 1 hour 17 minutes.Conclusion:Repeatedly reprocessed pedicle screws host corrosion, carbohydrate, fat, and soap, which could be a cause of surgical site infection and inflammatory responses postsurgery. The cause behind it is the impracticality of repeated cleaning and inspection of such devices.

Computer Aided Diagnosis System To Distinguish Adhd From Similar Behavioral Disorders

ADHD is one of the most prevalent psychiatric disorder of childhood, characterized by inattention and distractibility, with or without accompanying hyperactivity. The main aim of this research work is to develop a Computer Aided Diagnosis (CAD) technique with minimal steps that can differentiate the ADHD children from the other similar children behavioral disorders such as anxiety, depression and conduct disorder based on the Electroencephalogram (EEG) signal features and symptoms. The proposed technique is based on soft computing and bio inspired computing algorithms. Four non-linear features are extracted from the EEG such as Higuchi fractal dimension, Katz fractal dimension, Sevick fractal dimension and Lyapunov exponent and 14 symptoms which are most important in differentiation are extracted by experts in the field of psychiatry. Particle Swarm Optimization (PSO) tuned Back Propagation Neural Network (BPNN) and PSO tuned Radial Basis Function (RBF) employed as a classifier. By investigating these integrated features, we obtained good classification accuracy. Simulation results suggest that the proposed technique offer high potential in the diagnosis of ADHD and may be a good preliminary assistant for psychiatrists in diagnosing high risk behavioral disorders of children.

From Tree to Tape: Direct Synthesis of Pressure Sensitive Adhesives from Depolymerized Raw Lignocellulosic Biomass.

We report a new and robust strategy toward the development of high-performance pressure sensitive adhesives (PSAs) from chemicals directly obtained from raw biomass deconstruction. A particularly unique and translatable aspect of this work was the use of a monomer obtained from real biomass, as opposed to a model compound or lignin-mimic, to generate well-defined and nanostructure-forming polymers. Herein, poplar wood depolymerization followed by minimal purification steps (filtration and extraction) produced two aromatic compounds, 4-propylsyringol and 4-propylguaiacol, with high purity and yield. Efficient functionalization of those aromatic compounds with either acrylate or methacrylate groups generated monomers that could be easily polymerized by a scalable reversible addition–fragmentation chain-transfer (RAFT) process to yield polymeric materials with high glass transition temperatures and robust thermal stabilities, especially relative to other potentially biobased alternatives. These lignin-derived compounds were used as a major component in low-dispersity triblock polymers composed of 4-propylsyringyl acrylate and n-butyl acrylate (also can be biobased). The resulting PSAs exhibited excellent adhesion to stainless steel without the addition of any tackifier or plasticizer. The 180° peel forces were up to 4 N cm–1, and tack forces were up to 2.5 N cm–1, competitive with commercial Fisherbrand labeling tape and Scotch Magic tape, demonstrating the practical significance of our biomass-derived materials.

Image formation in the scanning helium microscope

The scanning helium microscope (SHeM) is a new addition to the array of available microscopies, particularly for delicate materials that may suffer damage under techniques utilising light or charged particles. As with all other microscopies, the specifics of image formation within the instrument are required to gain a full understanding of the produced micrographs. We present work detailing the basics of the subject for the SHeM, including the specific nature of the projection distortions that arise due to the scattering geometry. Extension of these concepts allowed for an iterative ray tracing Monte Carlo model replicating diffuse scattering from a sample surface to be constructed. Comparisons between experimental data and simulations yielded a minimum resolvable step height of (67 ± 5) µm and a minimum resolvable planar angle of (4.3 ± 0.3)° for the instrument in question.