Problem Of Amplification Research Articles

Numerical simulation of Raman and Brillouin laser-pulse amplification in a magnetized plasma

AbstractWe apply an Eulerian Vlasov code to study the amplification of an ultra-short seed pulse via stimulated Raman and Brillouin backscattering of energy from a long pump pulse, assumed at constant amplitude, in a plasma embedded in an external magnetic field. Detailed analysis of the spectra developed during the amplification process are presented, together with the evolution showing the pump depletion, accompanied by the counter-propagating seed-pulse amplification, compression and increased steepness of the waveform. In addition to the problem of the amplification of ultra-short seed pulses, there is an obvious academic interest in the study of problems of amplification of electromagnetic waves observed in many situations in laboratory plasmas and in the magnetosphere and other geophysical situations, such as in the environments of planets, where important variations in the presence and strength of magnetic fields are observed. The numerical code solves a one-dimensional relativistic Vlasov–Maxwell set of equations for a plasma in a magnetic field for both electrons and ions. We also apply the code to the problem of wakefield acceleration. The absence of noise in the Eulerian Vlasov code allows one to follow the evolution of the system with an accurate representation of the phase-space structures of the distribution functions.

Differential beamforming with circular microphone arrays

Differential beamforming cannot only achieve high directional gain but also can form frequency-invariant beampatterns. Therefore, it has the great potential to be widely used in voice communications to process broadband speech signals. The performance of a differential beamformer in terms of directivity factor (DF), white noise gain (WNG), and frequency invariance of the beampattern depends on many factors including the array geometry, the number of sensors, the inter-sensor spacing, etc. In the literature, most studies on differential beamforming have been focused on linear microphone arrays and not much efforts have been devoted to other array geometries. This paper is devoted to the study of circular microphone arrays. In comparison with linear arrays whose spatial response is a function of the steering angle, circular microphone arrays can have the same spatial response along many different directions. The focal point of this paper is on differential beamforming with uniform circular microphone arrays. The main topics addressed include: (1) major properties of circular microphone arrays, (2) how to design differential beamformers with different beampatterns, (3) how to design differential beamformers with different orders, and (4) how to achieve a good control of the white noise amplification problem, high directional gains, and frequency-independent responses.

Schrodinger's scat: a critical review of the currently available tiger (Panthera Tigris) and leopard (Panthera pardus) specific primers in India, and a novel leopard specific primer.

BackgroundNon-invasive sampling has opened avenues for the genetic study of elusive species, which has contributed significantly to their conservation. Where field based identity of non-invasive sample is ambiguous (e.g. carnivore scats), it is essential to establish identity of the species through molecular approaches. A cost effective procedure to ascertain species identity is to use species specific primers (SSP) for PCR amplification and subsequent resolution through agarose gel electrophoresis. However, SSPs if ill designed can often cross amplify non-target sympatric species. Herein we report the problem of cross amplification with currently published SSPs, which have been used in several recent scientific articles on tigers (Panthera tigris) and leopards (Panthera pardus) in India. Since these papers form pioneering research on which future work will be based, an early rectification is required so as to not propagate this error further.ResultsWe conclusively show cross amplification of three of the four SSPs, in sympatric non-target species like tiger SSP amplifying leopard and striped hyena (Hyaena hyaena), and leopard SSP amplifying tiger, lion (Panthera leo persica) and clouded leopard (Neofelis nebulosa), with the same product size. We develop and test a non-cross-amplifying leopard specific primer pair within the mitochondrial cytochrome b region. We also standardize a duplex PCR method to screen tiger and leopard samples simultaneously in one PCR reaction to reduce cost and time.ConclusionsThese findings suggest the importance of an often overlooked preliminary protocol of conclusive identification of species from non-invasive samples. The cross amplification of published primers in conspecifics suggests the need to revisit inferences drawn by earlier work.Electronic supplementary materialThe online version of this article (doi:10.1186/s12863-016-0344-y) contains supplementary material, which is available to authorized users.

A panel of PCR-inhibitory reference materials for quality evaluation of multiplex STR analysis kits

PCR inhibition is a critical parameter in forensic DNA analysis. Substances interfering with amplification of short tandem repeats (STRs) may generate partial and/or ambiguous DNA profiles. We present a strategy for developing a broad panel of PCR-inhibitory reference materials (RMs), representing common casework samples. Our panel, including solutions prepared from for example cigarettes, chewing gum and soil, is a tool for in-house validation and lot testing of STR systems. PowerPlex ESX 16 Fast System tolerated high levels of some RMs, but several substances caused amplification problems. Humic acid had a negative effect on amelogenin, moist snuff hindered amplification of longer fragments, and chewing gum caused generally lowered allele peak heights. Applying a broad panel of RMs ensures that a wide range of inhibitory substances are tested, giving an improved understanding of inhibitor tolerance and effects.

Divine Action and the Quantum Amplification Problem

For quantum mechanics to form the crux of a robust model of divine action, random quantum fluctuations must be amplified into the macroscopic realm. What has not been recognized in the divine action literature to date is the degree to which differential dynamics, continuum mechanics, and condensed matter physics prevent such fluctuations from infecting meso- and macroscopic systems. Once all of the relevant physics is considered, models of divine action based on quantum randomness are shown to be far more limited than is generally assumed. Unless some sort of new physical mechanism is discovered, the amplification problem cannot be solved.

Comparative study of two dna extraction methods in different tissues and conditions of degradation

The aim of tis study is to compare two methods of extraction of DNA from different tissues (spleen, liver, lungs, kidney, hearth, mussles, and pancreas) with Ph–CL and QIAAamp® DMNA Mini kit and to confirm which of this two methods give better results. Degradation of the tissues was in 3 controled conditions in a period of 6 months: room temperature, in a refridgerator on +4 and outside temperature in a period 2.3–7.8.2010 year. In total 210 analyses were performed and 20–30mg of the tissye was taken. Quantification was performed with Quantifiler kit on 7500 RealTime PCR ABI and analysed with 7500 System SDS version 1,2,3 software. Continuosly temperature was measure with digital TESTO termomethers on each 2h. Comparation of the two extraction protocols from the tissues was performed with T-test. Comparation of different tissues who were degradated in 3 controled conditions and extracted in 5 periods was performed with AMOVA. This study show that biger yeld of DNA from the tissues can be isolated with PhCl extraction method, but also with QIAAamp® DNA Mini kit eaven there is les amount of isolated DNA it can be used for further PCR reaction. PhCl method its slow, cancerogenous, more expenicve and can be problem in amplification proces because of big amount of DNA. Comparative results from different tissues show that there is no big diferences in the extracted yeld of DNA. We proved that in putrefied tissues non toxic and fast method can be used for DNA extraction. Our study show that there in no decerasing of isolated DNA with increasing of PMI and ambiental temperature, maybe because of the short period of 6 months that we analyse. Althout in forensic DNA analysis we should take in mind that quality and quantity of extracted DNA depends of ambiental conditions, PMI and type of the tissue. The fastes degradation hapends in tissues who have more proteolotyc enzymes.

Gaussian State Amplification with Noisy Observations

We consider the problem of channel state amplification in a Gaussian channel with additive Gaussian channel states, where the encoder observes noncausally a noisy version of these states. A complete characterization is provided for the minimum reconstruction distortion under a transmitter power constraint, and it is shown that a simple analog scheme with power control is optimal. More precisely, if the power available to the encoder is below certain threshold, the analog scheme using full power is optimal, however, when the power available to the encoder is above that threshold, analog transmission using only a fixed amount of the available power is optimal. Furthermore, the problem of simultaneous message transmission and Gaussian state amplification with noisy observations is studied, for which an inner bound and two nontrivial outer bounds to the optimal tradeoff between the transmission rate and the state reconstruction distortion are provided. The coding scheme underlying the inner bound combines analog signaling and Gelfand-Pinsker coding, where the latter deviates from the operating point of Costa’s dirty paper coding. The first outer bound is obtained by extending the channel decomposition technique, while the second outer bound requires a strategic analysis of the covariance matrix of the relevant random variables.

Remarks on the Performance of the Linear Detectors in MIMO Spatial Multiplexing Systems

Linear minimum mean square error (MMSE) detector has been shown to alleviate the noise amplification problem associated with the conventional zero-forcing (ZF) detector. In this paper, we analyze the performance improvement by the MMSE detector in terms of the condition number of its filtering matrix, the post-processing signal to noise ratio (SNR) improvement, and the variance of the postprocessing SNRs. To this end, we derive explicit formulas for the condition numbers of the filtering matrices and the post-processing SNRs. Analytical and simulation results demonstrate that the improvement achieved by the MMSE detector over the ZF detector does not only depend on the noise variance and the condition number of the channel matrix, but also on how close the smallest singular values are to the noise variance. This conjecture is also proven correct via analyzing the post-processing SNR of both detectors.

Announcement of the awards of JSE Outstanding Papers

Journal of Systematics and Evolution (JSE) has a long history of publishing papers on plant taxonomy and systematics in general.The journal can be traced back to the 1920's as "Contributions from the Biological Laboratory of the Science Society of China,Botanical Series," an influential Chinese journal at that time.In 1951,it was established as Acta Phytotaxonomica.

A next generation semiconductor based sequencing approach for the identification of meat species in DNA mixtures.

The identification of the species of origin of meat and meat products is an important issue to prevent and detect frauds that might have economic, ethical and health implications. In this paper we evaluated the potential of the next generation semiconductor based sequencing technology (Ion Torrent Personal Genome Machine) for the identification of DNA from meat species (pig, horse, cattle, sheep, rabbit, chicken, turkey, pheasant, duck, goose and pigeon) as well as from human and rat in DNA mixtures through the sequencing of PCR products obtained from different couples of universal primers that amplify 12S and 16S rRNA mitochondrial DNA genes. Six libraries were produced including PCR products obtained separately from 13 species or from DNA mixtures containing DNA from all species or only avian or only mammalian species at equimolar concentration or at 1:10 or 1:50 ratios for pig and horse DNA. Sequencing obtained a total of 33,294,511 called nucleotides of which 29,109,688 with Q20 (87.43%) in a total of 215,944 reads. Different alignment algorithms were used to assign the species based on sequence data. Error rate calculated after confirmation of the obtained sequences by Sanger sequencing ranged from 0.0003 to 0.02 for the different species. Correlation about the number of reads per species between different libraries was high for mammalian species (0.97) and lower for avian species (0.70). PCR competition limited the efficiency of amplification and sequencing for avian species for some primer pairs. Detection of low level of pig and horse DNA was possible with reads obtained from different primer pairs. The sequencing of the products obtained from different universal PCR primers could be a useful strategy to overcome potential problems of amplification. Based on these results, the Ion Torrent technology can be applied for the identification of meat species in DNA mixtures.

Medical image enhancement algorithm based on NSCT and the improved fuzzy contrast

ABSTRACTIn order to solve the problem of noise amplification, low contrast and image distortion in the process of medical image enhancement, a new algorithm is proposed which combines NSCT (nonsubsampled contourlet transform) and improved fuzzy contrast. The image is decomposed by NSCT. Firstly, linear enhancement method is used in low frequency coefficients; secondly the improved adaptive threshold function is used to deal with the high frequency coefficients. Finally, the improved fuzzy contrast is used to enhance the global contrast and the Laplace operator is used to enhance the details of the medical images. Experimental results show that the proposed algorithm can improve the image visual effects, remove the noise and enhance the details of medical images. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 7–14, 2015

Optically Controlled Signal Amplification for DNA Computation.

The hybridization chain reaction (HCR) and fuel-catalyst cycles have been applied to address the problem of signal amplification in DNA-based computation circuits. While they function efficiently, these signal amplifiers cannot be switched ON or OFF quickly and noninvasively. To overcome these limitations, a light-activated initiator strand for the HCR, which enabled fast optical OFF → ON switching, was developed. Similarly, when a light-activated version of the catalyst strand or the inhibitor strand of a fuel-catalyst cycle was applied, the cycle could be optically switched from OFF → ON or ON → OFF, respectively. To move the capabilities of these devices beyond solution-based operations, the components were embedded in agarose gels. Irradiation with customizable light patterns and at different time points demonstrated both spatial and temporal control. The addition of a translator gate enabled a spatially activated signal to travel along a predefined path, akin to a chemical wire. Overall, the addition of small light-cleavable photocaging groups to DNA signal amplification circuits enabled conditional control as well as fast photocontrol of signal amplification.

최소 Disturbance 기법을 적용한 향상된 CMA 적응 등화 알고리즘

This paper related with the ECMA (Enchanced CMA) algorithm performance which is possible to simultaneously compensation of the amplitude and phase by appling the minimum disturbance techniques in the CMA adatpve equalizer. The ECMA can improving the gradient noise amplification problem, stability and roburstness performance by the minimum disturbance technique that is the minimization of the equalizer tap weight variation in the point of squared euclidiean norm and the decision directed mode, and then the now cost function were proposed in order to simultaneouly compensation of amplitude and phase of the received signal with the minimum increment of computational operations. The performance of ECMA algorithm was compared to present MCMA by the computer simulation. For proving the performance, the recovered signal constellation that is the output of equalizer output signal and the residual isi and Maximum Distortion charateristic and MSE learning curve that are presents the convergence performance in the equalizer and the overall frequency transfer function of channel and equalizer were used. As a result of computer simulation, the ECMA has more better compensation capability of amplitude and phase in the recovered constellation, and the convergence time of adaptive equalization has improved compared to the MCMA.

On the design and implementation of linear differential microphone arrays.

Differential microphone array (DMA), a particular kind of sensor array that is responsive to the differential sound pressure field, has a broad range of applications in sound recording, noise reduction, signal separation, dereverberation, etc. Traditionally, an Nth-order DMA is formed by combining, in a linear manner, the outputs of a number of DMAs up to (including) the order of N - 1. This method, though simple and easy to implement, suffers from a number of drawbacks and practical limitations. This paper presents an approach to the design of linear DMAs. The proposed technique first transforms the microphone array signals into the short-time Fourier transform (STFT) domain and then converts the DMA beamforming design to simple linear systems to solve. It is shown that this approach is much more flexible as compared to the traditional methods in the design of different directivity patterns. Methods are also presented to deal with the white noise amplification problem that is considered to be the biggest hurdle for DMAs, particularly higher-order implementations.

Analysis of transient amplification for a torsional system passing through resonance

The classical problem of vibration amplification of a linear torsional oscillator excited by an instantaneous sinusoidal torque is re-examined with focus on the development of new analytical solutions of the transient envelopes. First, a new analytical method in the instantaneous frequency (or speed) domain is proposed to directly find the closed-form solutions of transient displacement, velocity, and acceleration envelopes for passage through resonance during the run-up or run-down process. The proposed closed-form solutions are then successfully verified by comparing them with numerical predictions and limited analytical solutions as available in prior literature. Second, improved analytical approximations of maximum amplification and corresponding peak frequency are found, which are also verified by comparing them with prior analytical or empirical formulas. In addition, applicability of the proposed analytical solution is clarified, and their error bounds are identified. Finally, the utility of analytical solutions and approximations is demonstrated by application to the start-up process of a multi-degree-of-freedom vehicle driveline system.

Serviceability assessment of the Góis footbridge using vibration monitoring

Footbridges are structures that may experience vibration amplification problems caused by pedestrian and/or wind actions. Design codes deal with these phenomena limiting the natural frequencies and the maximum accelerations expected. Aiming at taking into consideration these dynamic phenomena, current procedures to evaluate the structural performance of light-weight bridges based on experimental dynamic analysis are evaluated in this study. To achieve this, the dynamic response of three pedestrians walking, running and jumping was obtained. Maximum comfort limits of dynamic responses were then determined. The results indicate that codes could overestimate the level of vibration in this kind of footbridge.

Beyond synchronization: String instability in coupled harmonic oscillator systems

Summary In this paper, we consider the problem of disturbance response and error amplification for a simple system of coupled harmonic oscillators. We first suppose that identical oscillators are connected in a string in which each oscillator attempts to track its predecessor by using the same control law that depends on the relative position information from its immediate predecessor. Such an oscillator string is called a homogeneous oscillator string with predecessor-following architecture. Motivated by terminology from the problem of vehicle platooning, we say that the synchronized oscillator system is string unstable if the effect of a disturbance to the lead oscillator is amplified as it propagates along the string. With the use of a new Bode-like integral relation that must be satisfied by the complementary sensitivity function, we provide sufficient conditions for string instability. The sufficient conditions show that any string of oscillators that satisfies certain time domain performance specifications and bandwidth limitations must necessarily be string unstable. We further introduce a concept of time headway for the oscillator system and extend our analysis of string instability to consider the heterogeneous oscillator string and a more general communication range. Copyright © 2014 John Wiley & Sons, Ltd.

Time–frequency domain SNR estimation and its application in seismic data processing

Abstract Based on an approach estimating frequency domain signal-to-noise ratio (FSNR), we propose a method to evaluate time–frequency domain signal-to-noise ratio (TFSNR). This method adopts short-time Fourier transform (STFT) to estimate instantaneous power spectrum of signal and noise, and thus uses their ratio to compute TFSNR. Unlike FSNR describing the variation of SNR with frequency only, TFSNR depicts the variation of SNR with time and frequency, and thus better handles non-stationary seismic data. By considering TFSNR, we develop methods to improve the effects of inverse Q filtering and high frequency noise attenuation in seismic data processing. Inverse Q filtering considering TFSNR can better solve the problem of amplitude amplification of noise. The high frequency noise attenuation method considering TFSNR, different from other de-noising methods, distinguishes and suppresses noise using an explicit criterion. Examples of synthetic and real seismic data illustrate the correctness and effectiveness of the proposed methods.

Analysis of dynamic and fatigue effects in an old metallic riveted bridge

The fatigue behaviour of steel railway bridges is a complex phenomenon. On the one side, the Engineer must face the problem of dynamic amplification of the loads and their randomness, on the other side, the fatigue resistance is highly dependent on the load itself, since for different stress levels the material can sustain different number of cycles. This complexity makes the identification of the critical elements for structural safety a difficult task. In this context, and in the framework of the European research project FADLESS, the Laboratory of Vibrations and Monitoring (ViBest) of FEUP has conducted extensive research concerning the evaluation of dynamic effects and fatigue analysis of an old riveted railway bridge. Owing to the importance of this phenomenon, complementary numerical and experimental approaches have been used to assess fatigue effects. This article describes the main steps taken towards the goal of evaluating the dynamic behaviour and the fatigue life of this structure.

Primer Based Approach for PCR Amplification of High GC Content Gene:MycobacteriumGene as a Model

The genome of Mycobacterium is rich in GC content and poses problem in amplification of some genes, especially those rich in the GC content in terminal regions, by standard/routine PCR procedures. Attempts have been made to amplify three GC rich genes of Mycobacterium sp. (Rv0519c and Rv0774c from M. tuberculosis and ML0314c from M. leprae). Out of these three genes, Rv0774c gene was amplified with normal primers under standard PCR conditions, while no amplification was observed in case of Rv0519c and ML0314c genes. In the present investigation a modified primer based approach was successfully used for amplification of GC rich sequence of Rv0519c through codon optimization without changing the native amino acid sequence. The strategy was successfully confirmed by redesigning the standard primers with similar modifications followed by amplification of ML0314c gene.