Circuit Design Principles Research Articles

Principles of genetic circuit design.

Cells navigate environments, communicate and build complex patterns by initiating gene expression in response to specific signals. Engineers seek to harness this capability to program cells to perform tasks or create chemicals and materials that match the complexity seen in nature. This Review describes new tools that aid the construction of genetic circuits. Circuit dynamics can be influenced by the choice of regulators and changed with expression 'tuning knobs'. We collate the failure modes encountered when assembling circuits, quantify their impact on performance and review mitigation efforts. Finally, we discuss the constraints that arise from circuits having to operate within a living cell. Collectively, better tools, well-characterized parts and a comprehensive understanding of how to compose circuits are leading to a breakthrough in the ability to program living cells for advanced applications, from living therapeutics to the atomic manufacturing of functional materials.

NSF workshop report: Discovering general principles of nervous system organization by comparing brain maps across species

Efforts to understand nervous system structure and function have received new impetus from the federal Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative. Comparative analyses can contribute to this effort by leading to the discovery of general principles of neural circuit design, information processing, and gene-structure-function relationships that are not apparent from studies on single species. We here propose to extend the comparative approach to nervous system 'maps' comprising molecular, anatomical, and physiological data. This research will identify which neural features are likely to generalize across species, and which are unlikely to be broadly conserved. It will also suggest causal relationships between genes, development, adult anatomy, physiology, and, ultimately, behavior. These causal hypotheses can then be tested experimentally. Finally, insights from comparative research can inspire and guide technological development. To promote this research agenda, we recommend that teams of investigators coalesce around specific research questions and select a set of 'reference species' to anchor their comparative analyses. These reference species should be chosen not just for practical advantages, but also with regard for their phylogenetic position, behavioral repertoire, well-annotated genome, or other strategic reasons. We envision that the nervous systems of these reference species will be mapped in more detail than those of other species. The collected data may range from the molecular to the behavioral, depending on the research question. To integrate across levels of analysis and across species, standards for data collection, annotation, archiving, and distribution must be developed and respected. To that end, it will help to form networks or consortia of researchers and centers for science, technology, and education that focus on organized data collection, distribution, and training. These activities could be supported, at least in part, through existing mechanisms at NSF, NIH, and other agencies. It will also be important to develop new integrated software and database systems for cross-species data analyses. Multidisciplinary efforts to develop such analytical tools should be supported financially. Finally, training opportunities should be created to stimulate multidisciplinary, integrative research into brain structure, function, and evolution.

Servo-Control System Design of Automatic Production Line Based on PLC and HMI

Automatic production line includes machinery, electric, control, communication and other multi-disciplinary technologies and knowledge. It is an ideal training platform for students majored in mechatronics and electric automation. In the designing of platform, however, the difficulty lies in the precise delivery and position control of linear guide rail system. To address this problem, this paper aims at designing an AC servo-control system based on PLC, AC servo driver, servo motor and human-machine interface (HMI) and elaborates the principle of servo-control system, circuit design and software design. The system will achieve reliable delivery and precise positioning with position error less than 1 mm, which, with great application value, will meet the actual demand from industrial production.

Scaling of Topologically Similar Functional Modules Defines Mouse Primary Auditory and Somatosensory Microcircuitry

Mapping the flow of activity through neocortical microcircuits provides key insights into the underlying circuit architecture. Using a comparative analysis we determined the extent to which the dynamics of microcircuits in mouse primary somatosensory barrel field (S1BF) and auditory (A1) neocortex generalize. We imaged the simultaneous dynamics of up to 1126 neurons spanning multiple columns and layers using high-speed multiphoton imaging. The temporal progression and reliability of reactivation of circuit events in both regions suggested common underlying cortical design features. We used circuit activity flow to generate functional connectivity maps, or graphs, to test the microcircuit hypothesis within a functional framework. S1BF and A1 present a useful test of the postulate as both regions map sensory input anatomically, but each area appears organized according to different design principles. We projected the functional topologies into anatomical space and found benchmarks of organization that had been previously described using physiology and anatomical methods, consistent with a close mapping between anatomy and functional dynamics. By comparing graphs representing activity flow we found that each region is similarly organized as highlighted by hallmarks of small world, scale free, and hierarchical modular topologies. Models of prototypical functional circuits from each area of cortex were sufficient to recapitulate experimentally observed circuit activity. Convergence to common behavior by these models was accomplished using preferential attachment to scale from an auditory up to a somatosensory circuit. These functional data imply that the microcircuit hypothesis be framed as scalable principles of neocortical circuit design.

Design of Broadband, High-Speed Dual-Modulus Prescaler for Multi-Mode PLL Frequency Synthesizer

A architecture of multi-mode PLL frequency synthesizer one can meet a variety of communication standards is presented in this paper, which can provide each mode with the required frequency, while reducing the system's hardware cost. Optimized broadband high-speed dual-mode prescaler (DMP)'s internal structure, the principle of circuit design and its layout is introduced. The DMP is produced by 0.18μm CMOS technology. The post simulation results show that with the 1.8V power, the DMP's operating frequency range is 0.4 ~ 9.6GHz, the power consumption is 7.6mA.

Hardware Technology Research on Ultra-High Pressure Water Jet Ship Rust Control System Based on PLC

Ultra-high pressure water jet ship rust is one development direction of ship rust removal technique. In order to ensure the normal working of the system, how to control each equipment is the key-part of the design. This study presents the analytical research on hardware technology of the control system of ultra-high pressure water jet ship rust system, the analysis of the principle of frequency control system and circuit design and control circuit of PLC, by analysis the structure and principles of ultra-high pressure water jet rust, and then demonstrates through experimental test that the hardware electronic circuit works properly.

An improved technique of expanding metal ring experiment under high explosive loading

An experimental technique for metal expanding ring subjected to high explosive loading is conducted to significantly improve the loading stability compared with the traditional setup of two-end detonator initiation. Aspects of the circuit design, experimental arrangement, and initiation principle are illustrated in great detail. In terms of this experimental platform, we examine the velocity response of an individual ring, which demonstrates the experimental reproducibility. Moreover, fragmentation of multiple rings stacked on a metal driver is discussed.

Hot-wiring cells

Hot-wiring cells

Synthetic in vitro transcriptional oscillators.

The construction of synthetic biochemical circuits from simple components illuminates how complex behaviors can arise in chemistry and builds a foundation for future biological technologies. A simplified analog of genetic regulatory networks, in vitro transcriptional circuits, provides a modular platform for the systematic construction of arbitrary circuits and requires only two essential enzymes, bacteriophage T7 RNA polymerase and Escherichia coli ribonuclease H, to produce and degrade RNA signals. In this study, we design and experimentally demonstrate three transcriptional oscillators in vitro. First, a negative feedback oscillator comprising two switches, regulated by excitatory and inhibitory RNA signals, showed up to five complete cycles. To demonstrate modularity and to explore the design space further, a positive-feedback loop was added that modulates and extends the oscillatory regime. Finally, a three-switch ring oscillator was constructed and analyzed. Mathematical modeling guided the design process, identified experimental conditions likely to yield oscillations, and explained the system's robust response to interference by short degradation products. Synthetic transcriptional oscillators could prove valuable for systematic exploration of biochemical circuit design principles and for controlling nanoscale devices and orchestrating processes within artificial cells.

반도체 광 증폭기 XOR 논리게이트를 이용한 10 Gbps 전광 암호화 시스템의 구현

전자 논리회로에서 이용되는 전자신호 암호화와 같은 방법으로, 반도체 광 증폭기 XOR논리 게이트를 이용한 전광 암호화 시스템을 제안하였다. 시스템의 변수를 최적화 하고 전체 디자인 과정을 빠르게 수행하기 위해 정상상태와(steady state) 과도상태에(dynamic) 대한 전산모사가 차례로 이루어졌다. 심각한 신호 왜곡이 없이 10 Gbps 속도에서 일반적인 반도체 광 증폭기의 연속적 연결을 통해 전광 신호에 대한 암호화와 해독이 수행될 수 있음을 전산모사와 실험에 의한 결과를 통해 보여주었다. An all-optical encryption system built on the basis of electrical logic circuit design principles is proposed, using semiconductor optical amplifier (SOA) exclusive or (XOR) logic gates. Numerical techniques (steady-state and dynamic) were employed in a sequential manner to optimize the system parameters, speeding up the overall design process. The results from both numerical and experimental testbeds show that the encoding/decoding of the optical signal can be achieved at a 10 Gbps data rate with a conventional SOA cascade without serious degradation in the data quality.

Robust Engineered Circuit Design Principles for Stochastic Biochemical Networks With Parameter Uncertainties and Disturbances

Biochemical regulatory networks including genes, proteins and other regulatory molecules suffer from internal parametrical fluctuations (thermal, transcriptional, and splicing) as well as external noises (environmental and intercellular). Robustness is an essential property of intracellular biochemical regulatory networks to attenuate the effects of internal fluctuation and external noise. In this study, several system control schemes are proposed for the robust circuit control design of stochastic linear and nonlinear biochemical regulatory networks. First, the robust stability of genetic and proteomic regulatory networks is discussed under internal fluctuations. Then, the filtering ability of external noises is analyzed for stochastic biochemical regulatory networks. For the case where a biochemical regulatory network is not sufficiently robust to tolerate internal fluctuation and does not have enough filtering ability to filter the external noise, how to improve the robustness and noise filtering ability of stochastic biochemical regulatory networks by engineered control mechanisms is also proposed via biochemical circuit design. The proposed robust gene circuit design principles have potential applications for robust biosynthetic network design. Finally, two design examples are given in-silico to illustrate the design procedure and to confirm the performance of the proposed robust circuit design method.

Demonstration of 10 Gbps, all-optical encryption and decryption system utilizing SOA XOR logic gates

An all-optical encryption system built on the basis of electrical logic circuit design principles is proposed, using semiconductor optical amplifier (SOA) exclusive or (XOR) logic gates. Numerical techniques (steady-state and dynamic) were employed in a sequential manner to optimize the system parameters, speeding up the overall design process. The results from both numerical and experimental testbeds show that the encoding/decoding of the optical signal can be achieved at a 10 Gbps data rate with a conventional SOA cascade without serious degradation in the data quality.

Quantum Circuit Design and Analysis for Database Search Applications

In this paper, we show how quantum Boolean circuits can be used to implement the oracle and the inversion-about-average function in Grover's search algorithm. Before illustrating how this can be done, we present the circuit design principle using the satisfiability (SAT) problem as an example. Then, based on this principle, we show the quantum circuits for two different kinds of applications. The first one is searching a phone book. Although this is a typical example of Grover's algorithm, we show that it is impractical as a real-world application. As the second application, we give the quantum circuits for a more practical application-breaking a symmetric cryptosystem. Although these two applications have quite different types of search criteria, they are both one-way functions and the proposed circuits can actually be generalized to any such problems. In this perspective, we conclude this paper by proposing a template of quantum circuits that is capable of searching the solution of a certain class of one-way functions.

The analysis of UWB SiGe HBT LNA for its noise, linearity, and minimum group delay variation

The design of ultra-wideband (UWB) low-noise amplifiers (LNAs) require additional circuit design principles, which differ from those used in conventional LNAs. The design of a low-dc-power-consumption SiGe HBT LNA covering the 2-10-GHz range is demonstrated for UWB applications. Important design factors that must be carefully considered for UWB applications are analyzed, which include power dissipation, operating bandwidth, noise figure, group delay variation, and linearity. The dominant factor for low group delay variation in UWB LNAs is identified through the theoretical analysis. The linearity behavior over the wide bandwidth is analyzed and explained using the Volterra series. Second-harmonic cancellation is determined to be the dominant degradation factor for linearity. The implemented SiGe LNA achieves a gain of 13 dB, a minimum noise figure of 3.3 dB, and an input third-order intercept point of -7.5 dBm between 2-10 GHz while consuming a dc power of only 9.6 mW. This SiGe UWB LNA exhibits less than 22 ps of uniform group delay variation over the entire band.

Design of Permanent Magnet Systems Using Finite Element Analysis

Rare earth permanent magnets have a wide range of magnetic properties to meet the requirements of an extensive variety of applications. Sintered Sm 2Co 17-type magnets have the best thermal stability with high magnetic performance at temperatures up to 550 °C. Sintered NdFeB magnets have the highest maximum energy product, ( BH) max, but are limited to applications with relatively low operating temperatures. Bonded magnets offer some design flexibility at the expense of magnetic properties. In view of these complexities, it is very important to understand the critical factors when designing the magnetic circuit. Using design examples based on finite element analysis (FEA), we will discuss magnetic materials selection, magnetic circuit design principles and design trade-offs for various applications.

Design and characteristics of a high-precision chopper wheel motor driver

The circuit diagram and design principles of a high-stability chopper wheel motor driver are presented. Experimental results show that this unit can be interfaced to molecular-beam machines to generate supersonic beams with extremely stable root-mean-square and peak velocities fluctuating on a day-to-day basis by less than 0.2%.

Design of gene circuits: lessons from bacteria.

Researchers are now building synthetic circuits for controlling gene expression and considering practical applications for engineered gene circuits. What can we learn from nature about design principles for gene circuits? A large body of experimental data is now available to test some important theoretical predictions about how gene circuits could be organized, but the data also raise some intriguing new questions.

A TFT Strategy for Polymer Circuits

ABSTRACTAlthough integrated circuit design principles are well understood, they lead to the possibility of radically new modes of device operation when applied to conjugated polymers. Design for speed is very important, even when this is not a primary requirement for a particular application, since supply voltage can be reduced and with it power dissipation. For all-polymer circuits, on thermally insulating plastic substrates, device operating temperature will also be reduced. This has implications for device stability. There are a number of factors that are important in increasing circuit speed. Reduction of channel length must be accompanied by a reduction of gate overlap capacitance and this makes the conventional versions of bottom gate TFT perform badly. Vertical devices are a particularly attractive proposition providing that off-currents can be maintained at a low level. One approach is to use Schottky barriers as the source and drain. Examples will be explained, as will the very unusual mode of operation of such devices. Optimum load structures will also be defined.

Design principles for elementary gene circuits: Elements, methods, and examples.

The control of gene expression involves complex circuits that exhibit enormous variation in design. For years the most convenient explanation for these variations was historical accident. According to this view, evolution is a haphazard process in which many different designs are generated by chance; there are many ways to accomplish the same thing, and so no further meaning can be attached to such different but equivalent designs. In recent years a more satisfying explanation based on design principles has been found for at least certain aspects of gene circuitry. By design principle we mean a rule that characterizes some biological feature exhibited by a class of systems such that discovery of the rule allows one not only to understand known instances but also to predict new instances within the class. The central importance of gene regulation in modern molecular biology provides strong motivation to search for more of these underlying design principles. The search is in its infancy and there are undoubtedly many design principles that remain to be discovered. The focus of this three-part review will be the class of elementary gene circuits in bacteria. The first part reviews several elements of design that enter into the characterization of elementary gene circuits in prokaryotic organisms. Each of these elements exhibits a variety of realizations whose meaning is generally unclear. The second part reviews mathematical methods used to represent, analyze, and compare alternative designs. Emphasis is placed on particular methods that have been used successfully to identify design principles for elementary gene circuits. The third part reviews four design principles that make specific predictions regarding (1) two alternative modes of gene control, (2) three patterns of coupling gene expression in elementary circuits, (3) two types of switches in inducible gene circuits, and (4) the realizability of alternative gene circuits and their response to phased environmental cues. In each case, the predictions are supported by experimental evidence. These results are important for understanding the function, design, and evolution of elementary gene circuits. (c) 2001 American Institute of Physics.

Teaching MOS integrated circuit amplifier design to undergraduates

The enhancement-mode MOSFET is the primary active device used in present-day digital and mixed-signal integrated circuit processes. Thus, it is important to introduce this device and associated circuit design methods early in the electronics curriculum. This article discusses four integrated circuit MOSFET amplifier configurations; the current source/active load stage, the source follower, the cascode connection, and the differential stage with a current mirror load. These stages serve as building blocks for more complex MOSFET amplifiers and allow the introduction of MOSFET integrated circuit design principles.