Concept Of Amplification Research Articles

Spin amplification by controlled symmetry breaking for spin-based logic

Spin amplification is one of the most critical challenges for spintronics and spin-based logic in order to achieve spintronic circuits with fan-out. We propose a new concept for spin amplification that will allow a small spin current in a non-magnetic spin channel to control the magnetization of an attached ferromagnet. The key step is to bring the ferromagnet into an unstable symmetric state (USS), so that a small spin transfer torque from a small spin current can provide a magnetic bias to control the spontaneous symmetry breaking and select the final magnetization direction of the ferromagnet. Two proposed methods for achieving the USS configuration are voltage-controlled Curie temperature (VC-TC) and voltage-controlled magnetic anisotropy (VC-MA). We believe the development of new 2D magnetic materials with greater tunability of VC-TC and VC-MA will be needed for practical applications. A successful realization of spin amplification by controlled symmetry breaking will be important for the implementation of existing spin-logic proposals (e.g. ‘all spin logic’) and could inspire alternative ideas for spintronic circuits and devices.

Demonstration of a highly-sensitive tunable beam displacer with no use of beam deflection based on the concept of weak value amplification

We report the implementation of a highly sensitive tunable beam displacer based on the concept of weak value amplification, that allows to displace the centroid of a Gaussian beam a distance much smaller than its beam width without the need to deflect the direction of propagation of the input beam with movable optical elements. The beam's centroid position can be displaced by controlling the linear polarization of the output beam, and the dependence between the centroid's position and the angle of polarization is linear.

Self-induced parametric amplification arising from nonlinear elastic coupling in a micromechanical resonating disk gyroscope.

Parametric amplification, resulting from intentionally varying a parameter in a resonator at twice its resonant frequency, has been successfully employed to increase the sensitivity of many micro- and nano-scale sensors. Here, we introduce the concept of self-induced parametric amplification, which arises naturally from nonlinear elastic coupling between the degenerate vibration modes in a micromechanical disk-resonator, and is not externally applied. The device functions as a gyroscope wherein angular rotation is detected from Coriolis coupling of elastic vibration energy from a driven vibration mode into a second degenerate sensing mode. While nonlinear elasticity in silicon resonators is extremely weak, in this high quality-factor device, ppm-level nonlinear elastic effects result in an order-of-magnitude increase in the observed sensitivity to Coriolis force relative to linear theory. Perfect degeneracy of the primary and secondary vibration modes is achieved through electrostatic frequency tuning, which also enables the phase and frequency of the parametric coupling to be varied, and we show that the resulting phase and frequency dependence of the amplification follow the theory of parametric resonance. We expect that this phenomenon will be useful for both fundamental studies of dynamic systems with low dissipation and for increasing signal-to-noise ratio in practical applications such as gyroscopes.

Numerically exact solution of the many emitter–cavity laser problem: Application to the fully quantized spaser emission

A numerically exact solution to the many emitter -- cavity problem as an open many body system is presented. The solution gives access to the full, nonperturbative density matrix and thus the full quantum statistics and quantum correlations. The numerical effort scales with the third power in the number of emitters. Notably the solution requires none of the common approximations like good/bad cavity limit. As a first application the recently discussed concept of coherent surface plasmon amplification -- spaser -- is addressed: A spaser consists of a plasmonic nanostructure that is driven by a set of quantum emitters. In the context of laser theory it is a laser in the (very) bad cavity limit with an extremely high light matter interaction strength. The method allows us to answer the question of spasing with a fully quantized theory.

Design and synthesis of ultrasensitive off-on fluoride detecting fluorescence probe via autoinductive signal amplification.

We prepared an off-on fluorometric probe, DPF1, by incorporating the concept of autoinductive signal amplification into its molecular design. In the presence of fluoride, DPF1 undergoes a cascade of self-immolative reactions concomitant with unmasking fluorogenic coumarin, which results in the ejection of two fluoride ions. These fluoride ions are continuously activating the cascade reaction and accumulating coumarins, which leads to exponentially amplifying the signal with high sensitivity. The fluorescence signal generated by this cascade reaction is rapid, specific and insensitive to other anions. Its limit of detection was 0.5 pM, considerably lower than other current methods of fluoride detection. In addition, DCC, a long wavelength fluorometric probe, was prepared. Interestingly, an assay platform coupling DPF1 and DCC showed an outstanding sensing ability at higher wavelengths, suggesting that this can be a promising method for the sensitive and selective detection of fluoride in biological samples. The practical applicability of the proposed approach has been demonstrated in urine and water samples.

Biobar-Coded Gold Nanoparticles and DNAzyme-Based Dual Signal Amplification Strategy for Ultrasensitive Detection of Protein by Electrochemiluminescence

A dual signal amplification strategy for electrochemiluminescence (ECL) aptasensor was designed based on biobar-coded gold nanoparticles (Au NPs) and DNAzyme. CdSeTe@ZnS quantum dots (QDs) were chosen as the ECL signal probes. To verify the proposed ultrasensitive ECL aptasensor for biomolecules, we detected thrombin (Tb) as a proof-of-principle analyte. The hairpin DNA designed for the recognition of protein consists of two parts: the sequences of catalytical 8-17 DNAzyme and thrombin aptamer. Only in the presence of thrombin could the hairpin DNA be opened, followed by a recycling cleavage of excess substrates by catalytic core of the DNAzyme to induce the first-step amplification. One part of the fragments was captured to open the capture DNA modified on the Au electrode, which further connected with the prepared biobar-coded Au NPs-CdSeTe@ZnS QDs to get the final dual-amplified ECL signal. The limit of detection for Tb was 0.28 fM with excellent selectivity, and this proposed method possessed good performance in real sample analysis. This design introduces the new concept of dual-signal amplification by a biobar-coded system and DNAzyme recycling into ECL determination, and it is promising to be extended to provide a highly sensitive platform for various target biomolecules.

Target-responsive DNA-capped nanocontainer used for fabricating universal detector and performing logic operations.

Nucleic acids have become a powerful tool in nanotechnology because of their controllable diverse conformational transitions and adaptable higher-order nanostructure. Using single-stranded DNA probes as the pore-caps for various target recognition, here we present an ultrasensitive universal electrochemical detection system based on graphene and mesoporous silica, and achieve sensitivity with all of the major classes of analytes and simultaneously realize DNA logic gate operations. The concept is based on the locking of the pores and preventing the signal-reporter molecules from escape by target-induced the conformational change of the tailored DNA caps. The coupling of ‘waking up’ gatekeeper with highly specific biochemical recognition is an innovative strategy for the detection of various targets, able to compete with classical methods which need expensive instrumentation and sophisticated experimental operations. The present study has introduced a new electrochemical signal amplification concept and also adds a new dimension to the function of graphene-mesoporous materials hybrids as multifunctional nanoscale logic devices. More importantly, the development of this approach would spur further advances in important areas, such as point-of-care diagnostics or detection of specific biological contaminations, and hold promise for use in field analysis.

Parametric amplifier based dynamic clocked comparator

The dynamic clocked comparator using a parametric amplifier is proposed and designed using a concept of the charge transfer amplification (CTA). A low gain (5V/V) reverse discrete-time parametric amplifier (RDTPA) was used as a pre-amplifier stage of the proposed comparator. The level shifter scheme to nullify an input common-mode voltage (VCMI) shows minimal deviation for varying process corners. The complete design including the latch and the RDTPA is designed and fabricated in an STMicroelectronics 32nm CMOS technology with the supply voltage of 1V and a sampling frequency of 50MHz. The fabricated chip results show 7mV of an input offset voltage, 120μW of power consumption and 2.4pJ of energy per comparison.

Amplification of Angular Rotations Using Weak Measurements

We present a weak measurement protocol that permits a sensitive estimation of angular rotations based on the concept of weak-value amplification. The shift in the state of a pointer, in both angular position and the conjugate orbital angular momentum bases, is used to estimate angular rotations. This is done by an amplification of both the real and imaginary parts of the weak-value of a polarization operator that has been coupled to the pointer, which is a spatial mode, via a spin-orbit coupling. Our experiment demonstrates the first realization of weak-value amplification in the azimuthal degree of freedom. We have achieved effective amplification factors as large as 100, providing a sensitivity that is on par with more complicated methods that employ quantum states of light or extremely large values of orbital angular momentum.

Current understanding of signal amplification in phototransduction.

The studies of visual signal transduction, or phototransduction, have played a pivotal role in elucidating the most general principles of G protein signaling, particularly in regards to the concept of signal amplification, i.e., the process by which activation of a relatively small number of G protein coupled receptors is transformed into a robust downstream signaling event. In this essay, we summarize our current quantitative understanding of this process in living rods of lower and higher vertebrate animals. An integration of biochemical experiments in vitro with electrophysiological recordings from intact rod photoreceptors indicates that the total number of G protein molecules activated in the course of a light response to a single photon is ~16 in the mouse and ~60 in the frog. This further translates into hydrolysis of ~2000 and ~72 000 molecules of cGMP downstream of G protein, respectively, which represents the total degree of biochemical amplification in the phototransduction cascade.

Exploring urban parks and their peripheral food environments using a case study approach: Young people and obesogenic environments

Childhood overweight and obesity and physical inactivity are a major public health concern globally. This observational area-level case study examined and evaluated the attributes of two urban parks and 400 m peripheries influencing eating and activity behaviours in young people (aged 11–20 years). No single park variable principally or consistently attracted young people to parks or facilitated activity. Socio-economic advantage, however, was observed with higher park usership, food outlet provision (P=0.002) and food environment healthfulness (P=0.001) in more affluent areas. Inequities in obesogenic determinants are consistent with the concept of deprivation amplification. This issue needs to be more fully understood by urban designers and those involved in the planning, design and maintenance of urban parks and their peripheral environments. Furthermore, interdisciplinary cooperation and intervention between health and built environment professionals is needed to ensure that greater health equity is achieved for young people.

Measurement of sub-pulse-width temporal delays via spectral interference induced by weak value amplification

We demonstrate experimentally a scheme to measure small temporal delays, much smaller than the pulse width, between optical pulses. Specifically, we observe an interference effect, based on the concepts of quantum weak measurements and weak value amplification, through which a sub-pulsewidth temporal delay between two femtosecond pulses induces a measurable shift of the central frequency of the pulse. The amount of frequency shift, and the accompanying losses of the measurement, can be tailored by post-selecting different states of polarization. Our scheme requires only spectrum measurements and linear optics elements, hence greatly facilitating its implementation. Thus it appears as a promising technique for measuring small and rapidly varying temporal delays.

Towards novel non-chemically amplified (n-CARS) negative resists for electron beam lithography applications

A novel, non-chemically amplified negative resist was synthesized and characterized for next generation lithography applications. This resist material was shown to be directly sensitive to radiation without utilizing the concept of chemical amplification (CAR) and resulted in high-resolution 20 nm features. This resist design is accomplished by copolymers that are prepared from a monomer containing a sulfonium group which is sensitive to e-beam irradiation. Under 20 keV e-beam imaging and TMAH development, a sensitivity of 2.06 μC cm−2 and contrast of 1.8 were obtained. It has an LER of 20 nm, 10 line pattern varies from 1.8 ± 0.3 to 2.3 ± 0.4 nm.

Circle-to-circle amplification on a digital microfluidic chip for amplified single molecule detection.

We demonstrate a novel digital microfluidic nucleic acid amplification concept which is based on padlock probe mediated DNA detection and isothermal circle-to-circle amplification (C2CA). This assay platform combines two digital approaches. First, digital microfluidic manipulation of droplets which serve as micro-reaction chambers and shuttling magnetic particles between these droplets facilitates the integration of complex solid phase multistep assays. We demonstrate an optimized novel particle extraction and transfer protocol for superparamagnetic particles on a digital microfluidic chip that allows for nearly 100% extraction efficiencies securing high assay performance. Second, the compartmentalization required for digital single molecule detection is solved by simple molecular biological means, circumventing the need for complex microfabrication procedures necessary for most, if not all, other digital nucleic acid detection methods. For that purpose, padlock probes are circularized in a strictly target dependent ligation reaction and amplified through two rounds of rolling circle amplification, including an intermediate digestion step. The reaction results in hundreds of 500 nm sized individually countable DNA nanospheres per detected target molecule. We demonstrate that integrated miniaturized digital microfluidic C2CA results in equally high numbers of C2CA products μL(-1) as off-chip tube control experiments indicating high assay performance without signal loss. As low as 1 aM synthetic Pseudomonas aeruginosa DNA was detected with a linear dynamic range over 4 orders of magnitude up to 10 fM proving excellent suitability for infectious disease diagnostics.

Optimal design of ultrahigh-energy laser amplifier chain with high storage energy extraction

This paper presents the concept of constant-fluence amplification. It refers to the fact that laser fluence anywhere in the amplifier gain medium is identical to the design fluence E(design), which represents the maximum allowed fluence in consideration of the laser-induced damage threshold (LIDT). Based on this concept, we explore ideal amplifier model (IAM) and near-ideal amplifier chain (NIAC) and propose an optimal NIAC design method and analytically offer an indicator of the extraction efficiency. Finally, the paper discusses the influences of losses on the NIAC's extraction efficiency.

Theoretical study of power amplification in tapered fiber with multi-seed parallel injection

We proposed the concept of parallel injection power amplification. A tapered fiber amplifier with multi-seed sources by the way of parallel injection was studied. The lower-order modes are excited and more than 90% of the input signal power remains in the fiber core if optimal injection and taper design are set. The power in the doped-core is amplified with high optical-optical efficiency. When light is propagating along the fiber, the higher-order modes are filtered which results in the high output beam quality. Incoherent combination of multi-seed lights launched through the wide end gives rise to the output power of several kW.

Mediated Medication-Risk Messages: A Content Analysis of Print News Coverage of Increased Medication Risk

The social amplification of risk framework approaches risk as a combination of the objective risk of physical harm and the process through which individuals interpret the hazard. Within that framework, this study included a content analysis of media coverage of a changed risk profile of prescription medication. Considering frequency of news coverage as one cue to audience attention, results indicate that veterans as an at-risk population garner more media attention than children as an at-risk population. The concept of amplification was associated with an amplifying lead, the use of narrative, the identification of children as the at-risk population, and article length.

Development of a glass GEM

Gas electron multipliers (GEMs) apply the concept of gas amplification inside many tiny holes, realizing robust and high-gain proportional counters. However, the polyimide substrate of GEMs prevents them from being used in sealed detector applications. We have fabricated and tested glass GEMs (G-GEMs) with substrates made of photosensitive glass material from the Hoya Corporation. We fabricated G-GEMs with several different hole diameters and thicknesses and successfully operated test G-GEMs with a 100×100mm2 effective area. The uniformity of our G-GEMs was good, and the energy resolution for 5.9keV X-rays was 18.8% under uniform irradiation of the entire effective area. A gas gain by the G-GEMs of up to 6700 was confirmed with a gas mixture of Ar (70%)+CH4 (30%). X-ray imaging using the charge division readout method was demonstrated.

Risk amplification as social attribution

The Social Amplification of Risk Framework (SARF) occupies a significant position as a risk perception model and is widely recognised in risk management discourse particularly when controversial risk episodes are unfolding. This is despite criticism that it does not achieve its integrative goals to be an overarching framework for diverse social science approaches. This article accounts for the longevity of SARF and explores some of the longstanding philosophical issues. The concept of risk amplification as a social attribution is presented to strengthen the integrative appeal of the framework and to act as a counter to objections that the framework necessarily reifies risk, is ill equipped to describe social complexity and sides with the risk assessor against ‘non-expert’ stakeholders.

Active GaN MMIC diplexer based on distributed amplification concept

A review of the fundamentals of distributed amplification is presented along with the design and performance of a novel dual-band/diplexer monolithic distributed amplifier based on the combination of CRLH and RH transmission lines. The MMIC prototype, operating in the C-band and featuring a 10 dB gain with less than −20 dB crosstalk levels, represents the first monolithic implementation in GaN technology for this type of topology. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1041–1045, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27471