Reduced complexity MASH delta-sigma modulator
Ye, Zhipeng; Kennedy, Michael Peter
2007-01-01
A reduced complexity digital multi-stage noise shaping (MASH) delta-sigma modulator for fractional-N frequency synthesizer applications is proposed. A long word is used for the first modulator in a MASH structure; the sequence length is maximized by setting the least significant bit of the input to 1; shorter words are used in subsequent stages. Experimental results confirm simulations
All optical binary delta-sigma modulator
Sayeh, Mohammad R.; Siahmakoun, Azad
2005-09-01
This paper describes a novel A/D converter called "Binary Delta-Sigma Modulator" (BDSM) which operates only with nonnegative signal with positive feedback and binary threshold. This important modification to the conventional delta-sigma modulator makes the high-speed (>100GHz) all-optical implementation possible. It has also the capability to modify its own sampling frequency as well as its input dynamic range. This adaptive feature helps designers to optimize the system performance under highly noisy environment and also manage the power consumption of the A/D converters.
Superconducting bandpass delta-sigma modulator
Bulzacchelli, J. F.; Lee, H.-S.; Misewich, J. A.; Ketchen, M. B.
1999-11-01
Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS.
Superconducting bandpass delta-sigma modulator
Energy Technology Data Exchange (ETDEWEB)
Bulzacchelli, J.F.; Lee, H.-S. [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Misewich, J.A.; Ketchen, M.B. [IBM Research Division, T. J. Watson Research Center, Yorktown Heights, NY 10598 (United States)
1999-11-01
Bandpass delta-sigma modulators digitize narrowband signals with high dynamic range and linearity. The required sampling rate is only a few times higher than the centre frequency of the input. This paper presents a superconducting bandpass delta-sigma modulator for direct analogue-to-digital conversion of RF signals in the GHz range. The input signal is capacitively coupled to one end of a microstrip transmission line, and a single flux quantum balanced comparator quantizes the current flowing out of the other end. Quantization noise is suppressed at the quarter-wave resonance of the transmission line (about 2 GHz in our design). Circuit performance at a 20 GHz sampling rate has been studied with several long JSIM simulations. Full-scale (FS) input sensitivity is 20 mV (rms), and in-band noise is -53 dBFS and -57 dBFS over bandwidths of 39 MHz and 19.5 MHz, respectively. In-band intermodulation distortion is better than -69 dBFS. (author)
Automatisierte VHDL-Code-Generierung eines Delta-Sigma Modulators
Spilka, R.; Ostermann, T.
2006-09-01
Im vorliegenden Beitrag wird eine automatische Generierung des VHDL-Codes eines Delta-Sigma Modulators präsentiert. Die Koeffizientenmultiplikation wird hierbei durch Bit-Serielle-Addition durchgeführt. Mit Hilfe zweier neuer Matlab Funktionen wird der Systementwurf durch die bekannte Delta-Sigma Toolbox von R. Schreier erweitert und direkt synthesefähiger VHDL Code erzeugt.
Delta- Sigma Modulator with Signal Dependant Feedback Gain
National Research Council Canada - National Science Library
K.Diwakar; V.Vinoth Kumar
2015-01-01
Higher order Delta-Sigma Modulator (DSM) is basically an unstable system. The approximate conditions for stability cannot be used for the design of a DSM for industrial applications where risk is involved...
A High Performance Delta-Sigma Modulator for Neurosensing
National Research Council Canada - National Science Library
Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md Kafiul; Yang, Zhi
2015-01-01
... to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power...
Automatisierte VHDL-Code-Generierung eines Delta-Sigma Modulators
Directory of Open Access Journals (Sweden)
R. Spilka
2006-01-01
Full Text Available Im vorliegenden Beitrag wird eine automatische Generierung des VHDL-Codes eines Delta-Sigma Modulators präsentiert. Die Koeffizientenmultiplikation wird hierbei durch Bit-Serielle-Addition durchgeführt. Mit Hilfe zweier neuer Matlab Funktionen wird der Systementwurf durch die bekannte Delta-Sigma Toolbox von R. Schreier erweitert und direkt synthesefähiger VHDL Code erzeugt.
An analysis of nonlinear behavior in delta-sigma modulators
Ardalan, Sasan H.; Paulos, John J.
1987-06-01
The paper introduces a new method of analysis for delta-sigma modulators based on modeling the nonlinear quantizer with a linearized gain, obtained by minimizing a mean-square-error criterion, followed by an additive noise source representing distortion components. In the paper, input signal amplitude dependencies of delta-sigma modulator stability and signal-to-noise ratio are analyzed. It is shown that due to the nonlinearity of the quantizer, the signal-to-noise ratio of the modulator may decrease as the input amplitude increases prior to saturation. Also, a stable third-order delta-sigma modulator may become unstable by increasing the input amplitude beyond a certain threshold. Both of these phenomena are explained by the nonlinear analysis of this paper. The analysis is carried out for both dc and sinusoidal excitations.
Sliding mode control the delta-sigma modulation approach
Sira-Ramírez, Hebertt
2015-01-01
This monograph presents a novel method of sliding mode control for switch-regulated nonlinear systems. The Delta Sigma modulation approach allows one to implement a continuous control scheme using one or multiple, independent switches, thus effectively merging the available linear and nonlinear controller design techniques with sliding mode control. Sliding Mode Control: The Delta-Sigma Modulation Approach, combines rigorous mathematical derivation of the unique features of Sliding Mode Control and Delta-Sigma modulation with numerous illustrative examples from diverse areas of engineering. In addition, engineering case studies demonstrate the applicability of the technique and the ease with which one can implement the exposed results. This book will appeal to researchers in control engineering and can be used as graduate-level textbook for a first course on sliding mode control.
Sigma-delta modulator: loop filters and quantization noise
Directory of Open Access Journals (Sweden)
Golub V. S.
2013-05-01
Full Text Available In this paper the sigma-delta modulator was analyzed with the use of simulation. In particular, the author studied dependence of the quantization noise on the loop filtration. The obtained results explain certain operation features of the modulator and make it possible to give advice as to its application.
All optical asynchronous binary delta-sigma modulator
Tafazoli, M.; Davoudzadeh, N.; Sayeh, M. R.
2013-03-01
We present the first all optical delta-sigma modulator using a bistable device and a leaky integrator. In this paper, a novel tri-coupled ring geometry is utilized, resulting in resonance which is a building block for delta-sigma modulator. In each ring, the main active element is a semiconductor optical amplifier (SOA). The experimental result of the implemented setup is in a good agreement with our presented theory. Applying optical discrete components leads to a sampling rate of 660 kS/s. The higher frequency can be reached easily by using faster bistable devices and shorter loops.
Multiplexed noise shaping structures for Delta-Sigma modulators
Czarnul, Z.; Yesilyurt, A. G.; Temes, G. C.
1991-12-01
A new structure for realizing a multiplexed noise-shaping A/D convertor is proposed. It improves the performance of first- or second-order Delta-Sigma modulators by employing additional feedback paths for suppressing the quantizer error. The structure, its theoretical analysis, and simulations confirming the improved resolution are presented.
Adaptive Delta-Sigma Modulation for Enhanced Input Dynamic Range
Directory of Open Access Journals (Sweden)
Clemens M. Zierhofer
2008-06-01
Full Text Available An adaptive delta-sigma modulator of 1st order with one-bit quantization is presented. Adaptation is instantaneous and based on an exponential law. The feedback signal is a multibit discrete-level signal generated by a digital-to-analog converter (DAC. Compared to a nonadaptive delta-sigma modulator of 1st order, the input dynamic range is significantly enhanced. The gain in dynamic range is 6Ã¢Â€Â‰dB per bit defining the feedback amplitude. The influence of nonideal DAC performance is discussed. It is demonstrated that an implementation of the system is realistic with standard CMOS technology. To relax the requirements to the one-bit quantizer, the quantizer input signal is amplified adaptively (Q-Switching.
Sigma Delta Modulation Based Ternary FIR Filter Mapping on FPGA
Directory of Open Access Journals (Sweden)
Tayabuddin Memon
2011-07-01
Full Text Available In this paper single-bit SDM (Sigma Delta Modulation based TFF (Ternary FIR Filter with balanced ternary coefficients (i.e. -1/0/+1 has been mapped on small commercially available FPGAs (Field Programmable Gate Arrays. Filter coefficients were obtained using second order sigma delta modulator. The filter structure is based on a hierarchical adder tree that can easily be pipelined for high performance purpose. Filter structure was coded in VHDL (Very High Speed Integrated Circuit Hardware Description Language and simulated in Quartus-II software. The filter exhibits low I/O (Input Output and core area usage and high performance-achieving clock speeds close to 200MHz on a low-cost FPGA and over 500MHz on a latest FPGA commercially available device. This single-bit ternary filter is intended to support video and audio processing applications in mobile communication systems.
Adaptive Delta-Sigma Modulation for Enhanced Input Dynamic Range
Zierhofer, Clemens M.
2006-12-01
An adaptive delta-sigma modulator of 1st order with one-bit quantization is presented. Adaptation is instantaneous and based on an exponential law. The feedback signal is a multibit discrete-level signal generated by a digital-to-analog converter (DAC). Compared to a nonadaptive delta-sigma modulator of 1st order, the input dynamic range is significantly enhanced. The gain in dynamic range is 6 dB per bit defining the feedback amplitude. The influence of nonideal DAC performance is discussed. It is demonstrated that an implementation of the system is realistic with standard CMOS technology. To relax the requirements to the one-bit quantizer, the quantizer input signal is amplified adaptively (Q-Switching).
Continuous-Time Delta-Sigma Modulators for Wireless Communication
Andersson, Mattias
2014-01-01
The ever increasing data rates in wireless communication require analog to digital converters (ADCs) with greater requirements on speed and accuracy, while being power efficient to prolong battery life. This dissertation contains an introduction to the field and five papers that focus on the continuous-time (CT) Delta-Sigma modulator (DSM) as ADC. Paper I analyses the performance degradation of dynamic nonlinearity in the feedback DAC of the DSM, caused by Vth mismatch in the current-s...
Low-voltage switched-current delta-sigma modulator
Tan, Nianxiong; Eriksson, Sven
1995-05-01
This paper presents the design of a fully differential switched-current delta-sigma modulator using a single 3.3-V power-supply voltage. At system level, we tailor the modulator structure considering the similarity and difference of switched-capacitor and switched-current realizations. At circuit level, we propose a new switched-current memory cell and integrator with improved common mode feedback, without which low power-supply-voltage operation would not be possible. The whole modulator was implemented in a 0.8- micron double-metal digital CMOS process. It occupies an active area of 0.53 x 0.48 mm(sup 2) and consumes a current of 0.6 mA from a single 3.3-V power supply. The measured dynamic range is over 10 b.
Nanometer CMOS Sigma-Delta Modulators for Software Defined Radio
Morgado, Alonso; Rosa, José M
2012-01-01
This book presents innovative solutions for the implementation of Sigma-Delta Modulation (SDM) based Analog-to-Digital Conversion (ADC), required for the next generation of wireless hand-held terminals. These devices will be based on the so-called multistandard transceiver chipsets, integrated in nanometer CMOS technologies. One of the most challenging and critical parts in such transceivers is the analog-digital interface, because of the assorted signal bandwidths and dynamic ranges that can be required to handle the A/D conversion for several operation modes. This book describes new adaptive and reconfigurable SDM ADC topologies, circuit strategies and synthesis methods, specially suited for multi-standard wireless telecom systems and future Software-defined-radios (SDRs) integrated in nanoscale CMOS. It is a practical book, going from basic concepts to the frontiers of SDM architectures and circuit implementations, which are explained in a didactical and systematic way. It gives a comprehensive overview...
Improved stability and performance from sigma-delta modulators using 1-bit vector quantization
DEFF Research Database (Denmark)
Risbo, Lars
1993-01-01
A novel class of sigma-delta modulators is presented. The usual scalar 1-b quantizer in a sigma-delta modulator is replaced by a 1-b vector quantizer with a N-dimensional input state-vector from the linear feedback filter. Generally, the vector quantizer changes the nonlinear dynamics...
A 3rd Order Low Power Switched Current Sigma-Delta Modulator
DEFF Research Database (Denmark)
Jørgensen, Ivan Herald Holger; Bogason, Gudmundur
1996-01-01
This paper presents a 3rd order switched current Sigma-Delta modulator. The Sigma-Delta modulator operates at a sampling rate of 600kHz and the signal band is 5.5kHz, i.e. an oversampling factor of 54.5 is used. Multiple input signals are used to reduce the internal signal swings which results...
A High Performance Delta-Sigma Modulator for Neurosensing.
Xu, Jian; Zhao, Menglian; Wu, Xiaobo; Islam, Md Kafiul; Yang, Zhi
2015-08-07
Recorded neural data are frequently corrupted by large amplitude artifacts that are triggered by a variety of sources, such as subject movements, organ motions, electromagnetic interferences and discharges at the electrode surface. To prevent the system from saturating and the electronics from malfunctioning due to these large artifacts, a wide dynamic range for data acquisition is demanded, which is quite challenging to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power. The modulator was fabricated in a 0.18-µm CMOS process. Powered by a 1.0-V supply, the chip can achieve an 85-dB peak signal-to-noise-and-distortion ratio (SNDR) and an 87-dB dynamic range when integrated over a 10-kHz bandwidth. The total power consumption of the modulator is 13 µW, which corresponds to a figure-of-merit (FOM) of 45 fJ/conversion step. These competitive circuit specifications make this design a good candidate for building high precision neurosensors.
A High Performance Delta-Sigma Modulator for Neurosensing
Directory of Open Access Journals (Sweden)
Jian Xu
2015-08-01
Full Text Available Recorded neural data are frequently corrupted by large amplitude artifacts that are triggered by a variety of sources, such as subject movements, organ motions, electromagnetic interferences and discharges at the electrode surface. To prevent the system from saturating and the electronics from malfunctioning due to these large artifacts, a wide dynamic range for data acquisition is demanded, which is quite challenging to achieve and would require excessive circuit area and power for implementation. In this paper, we present a high performance Delta-Sigma modulator along with several design techniques and enabling blocks to reduce circuit area and power. The modulator was fabricated in a 0.18-µm CMOS process. Powered by a 1.0-V supply, the chip can achieve an 85-dB peak signal-to-noise-and-distortion ratio (SNDR and an 87-dB dynamic range when integrated over a 10-kHz bandwidth. The total power consumption of the modulator is 13 µW, which corresponds to a figure-of-merit (FOM of 45 fJ/conversion step. These competitive circuit specifications make this design a good candidate for building high precision neurosensors.
Delta- Sigma Modulator with Signal Dependant Feedback Gain
Directory of Open Access Journals (Sweden)
K.Diwakar
2015-02-01
Full Text Available Higher order Delta-Sigma Modulator (DSM is basically an unstable system. The approximate conditions for stability cannot be used for the design of a DSM for industrial applications where risk is involved. The conventional second order, single stage, single bit, unity feedback gain, discrete DSM cannot be used for the normalized full range (-1 to +1 of input signal since the DSM becomes unstable when the modulus of the input signal is above 0.55. The stability is also not guaranteed for amplitude of input signal less than 0.55. In this proposal, the conventional second order DSM is modified with input signal dependant feedback path gain. The proposed DSM is suitable for industrial applications where one needs the digital representation of the analog input signal, during each sampling period. This first configuration of proposed DSM can operate for the full range of input signal without causing instability. In order to improve the SNR of first configuration, it is combined with conventional second order DSM and proposed the second configuration of DSM.
Approximation Formula for Easy Calculation of Signal-to-Noise Ratio of Sigma-Delta Modulators
2011-01-01
The signal-to-noise ratio (SNR) is one of the most significant measures of performance of the sigma-delta modulators. An approximate formula for calculation of signal-to-noise ratio of an arbitrary sigma-delta modulator (SDM) has been proposed. Our approach for signal-to-noise ratio computation does not require modulator modeling and simulation. The proposed formula is compared with SNR calculations based on output bitstream obtained by simulations, and the reasons for small discrepancies are...
Space-time delta-sigma modulation for reception of multiple simultaneous independent RF beams
Rong, Guoguang; Black, Bruce A.; Siahmakoun, Azad Z.
2005-09-01
In this paper we introduce and analyze a multiple-RF-beam beamformer in receive mode utilizing the principle of space-time delta-sigma modulation. This principle is based on sampling input signals in both time and space and converting the sampled signals into a digital format by delta-sigma conversion. Noise shaping is achieved in 2D frequency domain. We show that the modulator can receive signals of narrow and wide bandwidths with steering capability, can receive multiple beams, and establish tradeoffs between sampling in time and in space. The ability of the modulator to trade off between time and space provides an effective way to sample high frequency RF signals without down conversion. In addition, a space-time delta-sigma modulator has better performance than a solely temporal delta-sigma modulator (for the same filter order), as is typically used in communication systems to digitize the down-converted analog signals.
Design and Simulation of First Order Sigma-Delta Modulator Using LT spice Tool
Directory of Open Access Journals (Sweden)
Prince Kumar Pandey
2014-07-01
Full Text Available A switched-capacitor single-stage Sigma-Delta ADC with a first-order modulator is proposed. Efficient low power first Order 1-Bit Sigma-Delta ADC designed which accepts input signal bandwidth of 10 MHz. This circuitry performs the function of an analog-to-digital converter. A first-order 1-Bit Sigma-Delta (Σ-Δ modulator is designed, simulated and analyzed using LTspice standard 250nm CMOS technology power supply of 1.8V. The modulator is proved to be robustness, the high performance in stability. The simulations are compared with those from a traditional analog-to-digital converter to prove that Sigma-Delta is performing better with low power and area.
Design of the 12-bit Delta-Sigma Modulator using SC Technique for Vibration Sensor Output Processing
Directory of Open Access Journals (Sweden)
M. Pavlik
2012-04-01
Full Text Available The work deals with the design of the 12-bit Delta-Sigma modulator using switched capacitors (SC technique. The modulator serves to vibration sensor output processing. The first part describes the Delta-Sigma modulator parameters definition. Results of the proposed topology ideal model were presented as well. Next, the Delta-Sigma modulator circuitry on the transistor level was done. The ONSemiconductor I2T100 0.7 um CMOS technology was used for design. Then, the Delta-Sigma modulator nonidealities were simulated and implemented into the MATLAB ideal model of the modulator. The model of real Delta-Sigma modulator was derived. Consequently, modulator coefficients were optimized. Finally, the corner analysis of the Delta-Sigma modulator with the optimized coefficients was simulated. The value of SNDR = 82.2 dB (ENOB = 13.4 bits was achieved.
A Multiplierless DC-Blocker for Single-Bit Sigma-Delta Modulated Signals
O'Shea Peter; Sadik Amin Z; Hussain Zahir M
2007-01-01
The DC content in single-bit domain is both undesirable and hard to remove. In this paper we propose a single-bit multiplierless DC-blocker structure. The input is assumed to be sigma-delta modulated bitstream. This DC-blocker is designed using a delta modulator topology with a sigma-delta modulator (SDM) embedded in its feedback path. Its performance is investigated in terms of the overall signal-to-noise ratio, the effectiveness of DC removal, and the stability. The proposed structure is e...
A Multiplierless DC-Blocker for Single-Bit Sigma-Delta Modulated Signals
Directory of Open Access Journals (Sweden)
O'Shea Peter
2007-01-01
Full Text Available The DC content in single-bit domain is both undesirable and hard to remove. In this paper we propose a single-bit multiplierless DC-blocker structure. The input is assumed to be sigma-delta modulated bitstream. This DC-blocker is designed using a delta modulator topology with a sigma-delta modulator (SDM embedded in its feedback path. Its performance is investigated in terms of the overall signal-to-noise ratio, the effectiveness of DC removal, and the stability. The proposed structure is efficient for hardware realisation.
Design of the 12-bit Delta-Sigma Modulator using SC Technique for Vibration Sensor Output Processing
Pavlik, M; Kledrowetz, V.; J. Haze
2012-01-01
The work deals with the design of the 12-bit Delta-Sigma modulator using switched capacitors (SC) technique. The modulator serves to vibration sensor output processing. The first part describes the Delta-Sigma modulator parameters definition. Results of the proposed topology ideal model were presented as well. Next, the Delta-Sigma modulator circuitry on the transistor level was done. The ONSemiconductor I2T100 0.7 um CMOS technology was used for design. Then, the Delta-Sigma modulator nonide...
Energy Technology Data Exchange (ETDEWEB)
Welling, P.A.
1977-09-01
The report describes the operation of the delta sigma modulator A-D converter and addresses the issues of integrating and hardening the circuit. The input/output relationship of the converter is stated for both DC and AC signals. A survey of commercial converters which use delta sigma modulation or related techniques is summarized. Various current switch designs, amplifier technologies, and resistive materials are examined to develop a radiation hard, integrated circuit configuration. A design which automatically nulls offset in the converter is outlined. (Author)
Design Methodology for a Maximum Sequence Length MASH Digital Delta-Sigma Modulator
Tao Xu; Marissa Condon
2009-01-01
The paper proposes a novel structure for a MASH digital delta-sigma modulator (DDSM) in order to achieve a long sequence length. The expression for the sequence length is derived. The condition to produce the maximum sequence length is also stated. It is proved that the modulator output only depends on the structure of the first-order error feedback modulator (EFM1) which is the first stage of a Multi-stAge noise SHaping (MASH) modulator.
A 1V low power second-order delta-sigma modulator for biomedical signal application.
Hsu, Chih-Han; Tang, Kea-Tiong
2013-01-01
This paper presents the design and implementation of a low-power delta-sigma modulator for biomedical application with a standard 90 nm CMOS technology. The delta-sigma architecture is implemented as 2nd order feedforward architecture. A low quiescent current operational transconductance amplifier (OTA) is utilized to reduce power consumption. This delta-sigma modulator operated in 1V power supply, and achieved 64.87 dB signal to noise distortion ratio (SNDR) at 10 KHz bandwidth with an oversampling ratio (OSR) of 64. The power consumption is 17.14 µW, and the figure-of-merit (FOM) is 0.60 pJ/conv.
Directory of Open Access Journals (Sweden)
L. Michaeli
2008-12-01
Full Text Available The paper deals with a novel approach to processing of pressure sensor signals. A bandpass sigma-delta modulator is used for this purpose. This technique is relatively new and it is not used widely, because this kind of modulator is usually utilized for wireless and video applications. Since the bandpass sigma-delta modulator works within its defined band it is resistant to offsets of its sub-circuits. The main stages of this modulator are implemented by means of switched-capacitor (SC technique. The article presents the basic ideas of this approach and simulation results of the first order of ideal and real modulator. The paper also shows the design of the phase locked loop (PLL block for synchronization of sensor signal and modulator driving signal. The simple evaluation board was fabricated for confirmation of the proposed principle. Also shown are the results of the chip testing, the modulator layout and the design and test results of the second order of bandpass sigma-delta modulator briefly.
A low noise high efficiency buck DC-DC converter with sigma-delta modulation
Energy Technology Data Exchange (ETDEWEB)
Cai Shujiang; Pi Changming; Yan Wei; Li Wenhong, E-mail: wenhongli@fudan.edu.cn [State Key Laboratory of ASIC and Systems, Fudan University, Shanghai 201203 (China)
2011-07-15
Some research efforts to improve the efficiency and noise performance of buck DC-DC converters are explored. A carefully designed power MOSFET driver, including a dead time controller, discontinuous current mode (DCM) controller and gate width controller, is proposed to improve efficiency. Instead of PWM modulation, sigma-delta modulation is introduced into the feedback loop of the converter to move out the clock-referred harmonic spike. The proposed converter has been designed and fabricated by a 0.35 {mu}m CMOS process. Measured results show that the peak efficiency of the converter can reach 93% and sigma-delta modulation suppresses the harmonic spike by 30 dB over PWM modulation. (semiconductor integrated circuits)
Delta-Sigma Modulated Displacement of a Digital Fluid Power Pump
DEFF Research Database (Denmark)
Johansen, Per; Roemer, Daniel Beck; Andersen, Torben Ole
2015-01-01
chambers of the pump are operated in full-stroke mode and a pulse density modulation method is used to approximate a desired displacement output. This pulse density modulation is performed with delta-sigma modulation, whereby the chamber activation pattern is determined. The method is implemented......Successful application of digital fluid power displacement pumps rely on proper control of the actively controlled high pressure and low pressure manifold valves. This paper concerns a method, where the valve timing control and the overall displacement modulation are separated. The displacement...
Kanno, Atsushi; Kawanishi, Tetsuya
2013-12-01
We propose a delta-sigma modulation scheme for low- and medium-frequency signal transmission in a digital photonic network system. A 10-Gb/s-class optical transceiver with a delta-sigma modulator utilized as a high-speed analog-to-digital converter (ADC) provides a binary optical signal. On the signal reception side, a low-cost and slow-speed photonic receiver directly converts the binary signal into an analog signal at frequencies from several hundreds of kilohertz several tens of megahertz. Further, by using a clock and data recovery circuit at the receiver to reduce jitters, the single-sideband phase noise of the generated signals can be significantly reduced.
Sigma-Delta 调制器的设计与仿真%Design and Simulation of a Sigma-Delta Modulator
Institute of Scientific and Technical Information of China (English)
黄锐敏; 杨清河; 陈兴; 梅丹丹
2015-01-01
This paper introduce a design method for the fifth-order digital Sigma-Delta modulator based on linear systems analysis and simulation fitting.Simulink simulation result shows that compared to the fourth-order modulator of oversam-pling ratio of 64,the oversampling ratio of the designed fifth-order modulator reduces to only 32,output signal to noise ratio can reach 104 dB,which improves 6 dB over the former design.Therefore,in the same oversampling ratio,this fifth-order modulator can get wider signal bandwidth.%提出一种基于线性系统分析和仿真拟合的5阶数字 Sigma-Delta 调制器的设计方法．Simulink 仿真结果表明：与过采样率为64的4阶调制器比较，所设计的5阶 Sigma-Delta 调制器在过采样率降低到只有32的情况下，输出信噪比可以达到104 dB，比前者改善了6 dB．因此，在相同过采样率下，该5阶调制器可以得到更宽的信号带宽．
On linearity of all optical asynchronous binary delta-sigma modulator
Davoudzadeh, N.; Tafazoli, M.; Sayeh, M. R.
2013-11-01
Since the role of optical signal processing is rapidly increasing within the communication systems, the opportunity to convert the analog signal to digital pulses directly in the optical domain will result in a systems simplification. Following our previous work, this paper describes a simple highly linear all-optical delta-sigma modulator, using the gain modulation in optically coupled single mode ring lasers. The key building blocks are an optical leaky integrator and a switching device, leading to meet the requirements of high-speed dynamic response, input/averaged-output linearity, and functioning without external clock. Linearity of the modulator and the corresponding parameters are discussed in theory, simulation, and experiment.
Study and analysis of coefficient mismatch in a MASH21 sigma-delta modulator
Energy Technology Data Exchange (ETDEWEB)
Ge Binjie; Wang Xin' an; Zhang Xing; Feng Xiaoxing; Wang Qingqin, E-mail: wangxa@szpku.edu.c [Key Laboratory of Integrated Microsystem Science and Engineering Applications, Shenzhen Graduate School of Peking University, Shenzhen 518055 (China)
2010-01-15
The quantization noise leakage of the first stage in a MASH21 sigma-delta modulator is analyzed. The results show that the finite DC gain of the opamp is the main reason for noise leakage, and finite GBW and SR only generate harmonic distortion. The relationship between DC gain and leakage is modeled and conclusions on design criteria are reached. As an example, a MASH21 modulator for a digital audio application is realized. This modulator, fabricated in an 0.18 {mu}m mixed signal process, achieves an SNDR of 91 dB with 1.8 V supply, which verifies the analysis and design criteria. (semiconductor integrated circuits)
A 10 MHz Bandwidth Continuous-Time Delta-Sigma Modulator for Portable Ultrasound Scanners
DEFF Research Database (Denmark)
Llimos Muntal, Pere; Jørgensen, Ivan Harald Holger; Bruun, Erik
2016-01-01
A fourth-order 1-bit continuous-time delta-sigma modulator designed in a 65 nm process for portable ultrasound scanners is presented in this paper. The loop filter consists of RCintegrators, with programmable capacitor arrays and resistors, and the quantizer is implemented with a high-speed clocked...... comparator and a pull-down clocked latch. The feedback signal is generated with voltage DACs based on transmission gates. Using this implementation, a small and low-power solution required for portable ultrasound scanner applications is achieved. The modulator has a bandwidth of 10 MHz with an oversampling...
Single-Bit All Digital Frequency Synthesis Using Homodyne Sigma-Delta Modulation.
Sotiriadis, Paul
2016-10-05
All-digital frequency synthesis using band-pass sigma-delta modulation to achieve spectrally clean single-bit output is presented and mathematically analyzed resulting in a complete model to predict stability and output spectrum. The quadrature homodyne filter architecture is introduced resulting in efficient implementations of carrier-frequency centred bandpass filters for the modulator. A multiplier-less version of the quadrature homodyne filter architecture is also introduced to reduce complexity maintaining clean in-band spectrum. MATLAB and SIMULINK simulation results present the potential capabilities of the synthesizer architectures and validate the accuracy of the developed theoretical framework.
Cost-effective bidirectional digitized radio-over-fiber systems employing sigma delta modulation
Lee, Kyung Woon; Jung, HyunDo; Park, Jung Ho
2016-11-01
We propose a cost effective digitized radio-over-fiber (D-RoF) system employing a sigma delta modulation (SDM) and a bidirectional transmission technique using phase modulated downlink and intensity modulated uplink. SDM is transparent to different radio access technologies and modulation formats, and more suitable for a downlink of wireless system because a digital to analog converter (DAC) can be avoided at the base station (BS). Also, Central station and BS share the same light source by using a phase modulation for the downlink and an intensity modulation for the uplink transmission. Avoiding DACs and light sources have advantages in terms of cost reduction, power consumption, and compatibility with conventional wireless network structure. We have designed a cost effective bidirectional D-RoF system using a low pass SDM and measured the downlink and uplink transmission performance in terms of error vector magnitude, signal spectra, and constellations, which are based on the 10MHz LTE 64-QAM standard.
Switching Arithmetic for DC to DC Converters Using Delta Sigma Modulator Based Control Circuit
Directory of Open Access Journals (Sweden)
K.Diwakar
2016-02-01
Full Text Available In the proposed arithmetic unit for dc to dc converters using delta sigma modulator, a new technique is proposed for addition and multiplication of sampled analog signals. The output is in digital form to drive the converters. The conventional method has input signal limitation whereas in the proposed method the inputs can vary to full-scale. The addition of two discrete signals is done by sampling the two signals at a period called update period and feeding each signal to the input of signal dependant delta sigma modulator for half of the update period and combining the outputs for the update period. The extension of three discrete data addition can be carried out by using the same technique. For the multiplication of two discrete signals different method is adopted. One analog signal is fed to the input of first delta-sigma modulator (DSM1 after sampling. The sampled output of the second analog signal is negated or not negated depending on the bit state at the output of DSM1 and is fed to the input of second DSM(DSM2. The resulting bit stream at the output of DSM2 is the digital representation of the product of the sampled data of the two analog signals. In order to multiply three discrete data, the sampled output of third data is negated or not negated depending on the bit state at the output of DSM2 and is fed to the input of third DSM(DSM3. The resulting bit stream at the output of DSM3 is the digital representation of the product of the sampled data of the three analog signals. Using the proposed adder and multiplier circuits any expressions can be evaluated such that the average value of the digital output of the arithmetic unit over the update period gives the value of expressions during that period. The digital output of the arithmetic unit is used to drive the dc-dc converters.
Second-order sigma-delta modulator in standard cmos technology
Directory of Open Access Journals (Sweden)
Milovanović Dragiša
2004-01-01
Full Text Available As a part of wider project sigma-delta modulator was designed. It represents an A/D part of a power meter IC. Requirements imposed were: SNDR and dynamic range > 50 dB for maximum input swing of 250 mV differential at 50 Hz. Over sampling ratio is 128 with clock frequency of 524288 Hz which gives bandwidth of 2048 Hz. Circuit is designed in 3.3 V supply standard CMOS 0.35 µm technology.
Hirata, S.; Kurosawa, M. K.; Katagiri, T.
Ultrasonic distance measurement is based on determining the time of flight of ultrasonic wave. The pulse compression technique that obtains the cross-correlation function between the received signal and the reference signal is used to improve the resolution of distance measurement. The cross-correlation method requires high-cost digital signal processing. This paper presents a cross-correlation method using a delta-sigma modulated single-bit digital signal. Sensor signal processing composed of the cross-correlation between two single-bit signals and a post-moving average filter is proposed and enables reducing the cost of digital signal processing.
Optimization of Modulator and Circuits for Low Power Continuous-Time Delta-Sigma ADC
DEFF Research Database (Denmark)
Marker-Villumsen, Niels; Bruun, Erik
2014-01-01
This paper presents a new optimization method for achieving a minimum current consumption in a continuous-time Delta-Sigma analog-to-digital converter (ADC). The method is applied to a continuous-time modulator realised with active-RC integrators and with a folded-cascode operational transconduc......- tance amplifier (OTA). Based on a detailed circuit analysis of the integrator and the OTA, key expression are derived relating the biasing current of the OTA to the noise requirements of the integrator. In the optimization the corner frequency of the modulator loop filter and the number of quantizer...... levels are swept. Based on the results of the circuit analysis, for each modulator combination the summed current consumption of the 1st integrator and quantizer of the ADC is determined. By also sweeping the partitioning of the noise power for the different circuit parts, the optimum modulator...
Low-power switched-capacitor delta-sigma modulator for EEG recording applications
Energy Technology Data Exchange (ETDEWEB)
Chen Jin; Zhang Xu; Chen Hongda, E-mail: chenjin@semi.ac.c [State Key Laboratory of Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)
2010-07-15
This paper presents a third-order single-loop delta-sigma modulator of a biomedical micro-system for portable electroencephalogram (EEG) monitoring applications. To reduce the power consumption, the loop filter of the proposed modulator is implemented by applying a switched-capacitor structure. The modulator is designed in a 0.35-{mu}m 2P4M standard CMOS process, with an active area of 365 x 290 {mu}m{sup 2}. Experimental results show that this modulator achieves a 68 dB dynamic range with an input sinusoidal signal of 100 Hz signal bandwidth under a 64 over-sampling ratio. The whole circuit consumes 515 {mu}W under a 2.5 V power supply, which is suitable for portable EEG monitoring.
On the synthesis and optimization of cascaded continuous-time Sigma-Delta modulators
Directory of Open Access Journals (Sweden)
M. Keller
2006-01-01
Full Text Available Up to now, there exist two completely different approaches for the synthesis of cascaded CT Sigma-Delta modulators. While the first method is based on a DT prototype and thus on the application of a DT-to-CT transformation, the second one is entirely performed in the CT domain. In this contribution, the method of lifting will be applied to overcome the disadvantages afflicted with the first method (e.g. less ideal anti-aliasing filter performance, increased circuit complexity and to establish a time efficient DT simulation model for the second method. Thereby, optimal modulator coefficients as well as optimal digital cancellation filters for an arbitrary cascaded CT modulator can be simulated in an efficient and rapid manner. For illustrative purposes, the complete synthesis procedure is demonstrated by the example of a 2-1-1 cascaded CT modulator.
SEMICONDUCTOR INTEGRATED CIRCUITS: Sigma-delta modulator modeling analysis and design
Binjie, Ge; Xin'an, Wang; Xing, Zhang; Xiaoxing, Feng; Qingqin, Wang
2010-09-01
This paper introduces a new method for SC sigma-delta modulator modeling. It studies the integrator's different equivalent circuits in the integrating and sampling phases. This model uses the OP-AMP input pair's tail current (I0) and overdrive voltage (von) as variables. The modulator's static and dynamic errors are analyzed. A group of optimized I0 and von for maximum SNR and power × area ratio can be obtained through this model. As examples, a MASH21 modulator for digital audio and a second order modulator for RFID baseband are implemented and tested, and they can achieve 91 dB and 72 dB respectively, which verifies the modeling and design criteria.
Kanemoto, Daisuke; Ido, Toru; Taniguchi, Kenji
A low power and high performance with third order delta-sigma modulator for audio applications, fabricated in a 0.18µm CMOS process, is presented. The modulator utilizes a third order noise shaping with only one opamp by using an opamp sharing technique. The opamp sharing among three integrator stages is achieved through the optimal operation timing, which makes use of the load capacitance differences between the three integrator stages. The designed modulator achieves 101.1dB signal-to-noise ratio (A-weighted) and 101.5dB dynamic range (A-weighted) with 7.5mW power consumption from a 3.3V supply. The die area is 1.27mm2. The fabricated delta-sigma modulator achieves the highest figure-of-merit among published high performance low power audio delta-sigma modulators.
A low-noise delta-sigma phase modulator for polar transmitters.
Zhou, Bo
2014-01-01
A low-noise phase modulator, using finite-impulse-response (FIR) filtering embedded delta-sigma (ΔΣ) fractional-N phase-locked loop (PLL), is fabricated in 0.18 μ m CMOS for GSM/EDGE polar transmitters. A simplified digital compensation filter with inverse-FIR and -PLL features is proposed to trade off the transmitter noise and linearity. Experimental results show that the presented architecture performs RF phase modulation well with 20 mW power dissipation from 1.6 V supply and achieves the root-mean-square (rms) and peak phase errors of 4° and 8.5°, respectively. The measured and simulated phase noises of -104 dBc/Hz and -120 dBc/Hz at 400-kHz offset from 1.8-GHz carrier frequency are observed, respectively.
Correlation-based correction of sound velocity inhomogeneities using delta-sigma modulators.
Li, P C; Huang, J J; O'Donnell, M
2000-10-01
Delta-sigma (deltasigma) modulator based beamformers have been proposed for high-quality ultrasonic imaging. Due to the high sampling rate and single bit data width, the cost and complexity of the receive beamformer can be significantly reduced. It was shown that with proper dynamic focusing controls, equivalent image quality could be achieved with an adequate signal-to-quantization noise ratio (SQNR). In this paper, deltasigma modulator based beamformers are used for correlation-based phase aberrations correction of sound velocity inhomogeneities in the body. It is shown that the correction can be efficiently implemented at a performance level similar to that of a conventional radio frequency (rf) beamformer. In addition, more than 6 dB contrast improvement is demonstrated. The different dynamic focusing techniques are also investigated in the context of phase aberration correction. It is shown that the single bit dynamic focusing approach does not affect the overall performance of phase aberration correction.
An improved single-loop sigma-delta modulator for GSM applications
Institute of Scientific and Technical Information of China (English)
Li Hongyi; Wang Yuan; Jia Song; Zhang Xing
2011-01-01
Traditional feedforward structures suffer from performance constraints caused by the complex adder before quantizer.This paper presents an improved 4th-order l-bit sigma-delta modulator which has a simple adder and delayed input feedforward to relax timing constraints and implement low-distortion.The modulator was fabricated in a 0.35μm CMOS process,and it achieved 92.8 dB SNDR and 101 dB DR with a signal bandwidth of 100 kHz dissipating 8.6 mW power from a 3.3-V supply.The performance satisfies the requirements of a GSM system.
A Low-Noise Delta-Sigma Phase Modulator for Polar Transmitters
Directory of Open Access Journals (Sweden)
Bo Zhou
2014-01-01
Full Text Available A low-noise phase modulator, using finite-impulse-response (FIR filtering embedded delta-sigma (ΔΣ fractional-N phase-locked loop (PLL, is fabricated in 0.18 μm CMOS for GSM/EDGE polar transmitters. A simplified digital compensation filter with inverse-FIR and -PLL features is proposed to trade off the transmitter noise and linearity. Experimental results show that the presented architecture performs RF phase modulation well with 20 mW power dissipation from 1.6 V supply and achieves the root-mean-square (rms and peak phase errors of 4° and 8.5°, respectively. The measured and simulated phase noises of −104 dBc/Hz and −120 dBc/Hz at 400-kHz offset from 1.8-GHz carrier frequency are observed, respectively.
COMPARISON OF SIGMA-DELTA MODULATOR FOR FRACTIONAL-N PLL FREQUENCY SYNTHESIZER
Institute of Scientific and Technical Information of China (English)
Mao Xiaojian; Yang Huazhong; Wang Hui
2007-01-01
This paper investigates the design of digital Sigma-Delta Modulator(SDM)for fractional-N frequency synthesizer.Characteristics of SDMs are compared through theory analysis and simulation.The curve of maximum-loop-bandwidth vs.maximum-phase-noise is suggested to be a new criterion to the performance of SDM.which greatly helps designers to select an appropriate SDM structure to meet their real application requirements and to reduce the cost as low as possible.A low-spur 3-order Multistage Noise Shaping(MASH)-1-1-1 SDM using three 2-bit first-order cascaded modulators is proposed,which balances the requirements of tone-free and maximum operation frequency.
Delta-Sigma Modulated Photodetection Method to Reduce Laser Power Project
National Aeronautics and Space Administration — This delta-sigma technique may be thought of as a form of analog-to-digital converter (ADC). The proposed network offers a means of processing electronic signals...
Realization of High-Order Filters for 1-bit Signal Processing Based on Delta-Sigma Modulation
Murahashi, Yoshimitsu; Doki, Shinji; Okuma, Shigeru
We discuss a realization method of basic 1-bit signal processing based on Delta-Sigma modulation in this paper. Additionally, we show the characteristics of basic 1-bit processor and an effective design method from the view point of SNR. As the application of the 1-bit signal processing, we proposed a realization method of high-order filters based on Delta-Sigma modulation. We applied the effective design method to decide coefficients of a 4th-order butterworth low pass filter. We show that the filter designed by using the proposed method achieves the highest SNR.
Systematic Design Methodology of a Wideband Multibit Continuous-Time Delta-Sigma Modulator
Directory of Open Access Journals (Sweden)
Awinash Anand
2013-01-01
Full Text Available Systematic design of a low power, wideband and multi-bit continuous-time delta-sigma modulator (CTDSM is presented. The design methodology is illustrated with a 640 MS/s, 20 MHz signal bandwidth 4th order 2-bit CTDMS implemented in 0.18 µm CMOS technology. The implemented design achieves a peak SNDR of 65.7 dB and a high dynamic range of 70 dB while consuming only 19.7 mW from 1.8 V supply. The design achieves a FoM of 0.31 pJ/conv. Direct path compensation is employed for one clock excess loop delay compensation. In the feedforward topology, capacitive summation using the last opamp eliminates extra summation opamp.
DEFF Research Database (Denmark)
Jørgensen, Ivan Harald Holger; Bogason, Gudmundur
1998-01-01
This paper presents a third order switched current sigma delta-modulator. The modulator is optimized at the system level for minimum power consumption by careful design of the noise transfer function. A thorough noise analysis of the cascode type current copiers used to implement the modulator......, together with a new methodology for evaluating the nonlinear settling behavior is presented. This leads to a new optimization methodology that minimize the power consumption in switched current circuits for given design parameters. The optimization methodology takes process variations into account...... to internal clamping in the integrators and proper scaling the modulator shows excellent stability properties. In order to compare the performance of the modulator presented in this paper to other sigma delta-modulators two figure-of-merits (FOMs) are proposed. From these figure-of-merits it is found...
Continuous-Time Delta-Sigma Modulators: Tutorial Overview, Design Guide, and State-of-the-Art Survey
Dosho, Shiro
This paper presents a tutorial overview of Continuous-Time Delta-Sigma Modulators (CTDSM); their operating principles to understand what is important intuitively and architectures to achieve higher conversion efficiency and to operate low supply voltage, design methods against loop stability problem, tuning methods of the bandwidth and so on. A survey of cutting-edge CMOS implementations is described.
Siahmakoun, A.; Reeves, E.; Costanzo-Caso, P.
2015-03-01
A novel photonic analog-to-digital converter (ADC) based on asynchronous delta-sigma modulation (ADSM) has been investigated. The architecture utilizes an optical leaky integrator, optoelectronic bistable quantizer, and positive corrective feedback for a non-interferometric optical implementation of ADSM. The principles of the proposed 1st -order ADSM are mathematically modeled and simulated.
Li, Haibo; Hu, Rong; Yang, Qi; Luo, Ming; He, Zhixue; Jiang, Peng; Liu, Yongpiao; Li, Xiang; Yu, Shaohua
2017-01-09
An improved high-order delta-sigma modulator with multi-level quantizer is proposed to enable carrier aggregation of 4G-LTE signals in mobile fronthaul. Different from conventional delta-sigma modulation-based digital mobile fronthaul, a 2-bit quantizer is employed to reduce the quantization noise, which enabling the transmission via PAM-4 based IM-DD channel. Moreover, we employ the 4th-order high-pass filter (HPF) to replace the 1st-order HPF in the conventional delta-sigma modulator, resulting in a much better noise shaping performance. In the experiment, a PAM-4 based mobile fronthaul transmission of 32 aggregated 4G-LTE signals with a CPRI equivalent data rate of 39.32-Gb/s is demonstrated in a single-λ 10-Gb/s IM-DD channel. Significant improvement of 68% is achieved in the average EVM performance compared to the previous delta-sigma modulation-based digital mobile fronthaul.
Kitayabu, Toru; Hagiwara, Mao; Ishikawa, Hiroyasu; Shirai, Hiroshi
A novel delta-sigma modulator that employs a non-uniform quantizer whose spacing is adjusted by reference to the statistical properties of the input signal is proposed. The proposed delta-sigma modulator has less quantization noise compared to the one that uses a uniform quantizer with the same number of output values. With respect to the quantizer on its own, Lloyd proposed a non-uniform quantizer that is best for minimizing the average quantization noise power. The applicable condition of the method is that the statistical properties of the input signal, the probability density, are given. However, the procedure cannot be directly applied to the quantizer in the delta-sigma modulator because it jeopardizes the modulator's stability. In this paper, a procedure is proposed that determine the spacing of the quantizer with avoiding instability. Simulation results show that the proposed method reduces quantization noise by up to 3.8dB and 2.8dB with the input signal having a PAPR of 16dB and 12dB, respectively, compared to the one employing a uniform quantizer. Two alternative types of probability density function (PDF) are used in the proposed method for the calculation of the output values. One is the PDF of the input signal to the delta-sigma modulator and the other is an approximated PDF of the input signal to the quantizer inside the delta-sigma modulator. Both approaches are evaluated to find that the latter gives lower quantization noise.
Design of resolution/power controllable Asynchronous Sigma-Delta Modulator
Deshmukh, Anita Arvind; Deshmukh, Raghvendra B.
2016-12-01
This paper presents the design of a Programmable Asynchronous Modulator (PAM) with field control of resolution and power. A novel variable hysteresis Schmitt Trigger (ST) is used for external programmability. Asynchronous Sigma-Delta Modulator (ASDM) implementation with external control voltages is proposed to supervise the resolution and power. This architecture with reduced circuit complexity considerably improves the earlier realizations by eliminating multiple current sources as well switched capacitor circuits and results in power saving up to 87 %. Proposed PAM design demonstrates an improved SNDR of 115 dB, DR of 96 dB, and power consumption below 280 μW. It illustrates Effective Number of Bits (ENOB) to 18.81 and Figure of Merit (FoM) to 0.15 fJ/conversion step. Modulator is implemented in Cadence UMC Hspice 0.18 μm CMOS analog technology. Off-chip PAM control for resolution/power performance has potential applications in battery operated ultra low power applications like IoT; where ADC is one of the major power consuming components. It offers the promise for an efficient performance with power saving.
Energy Technology Data Exchange (ETDEWEB)
Bulzacchelli, John F [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Lee, Hae-Seung [Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hong, Merit Y [Motorola, Inc., Semiconductor Products Sector, Tempe, AZ 85284 (United States); Misewich, James A [IBM Research Division, T J Watson Research Center, Yorktown Heights, NY 10598 (United States); Ketchen, Mark B [IBM Research Division, T J Watson Research Center, Yorktown Heights, NY 10598 (United States)
2003-12-01
Segmented correlation is a useful technique for testing a superconducting analogue-to-digital converter, as it allows the output spectrum to be estimated with fine frequency resolution even when data record lengths are limited by small on-chip acquisition memories. Previously, we presented segmented correlation measurements on a superconducting bandpass delta-sigma modulator sampling at 40.2 GHz under idle channel (no input) conditions. This paper compares the modulator output spectra measured by segmented correlation with and without an input tone. Important practical considerations of calculating segmented correlations are discussed in detail. Resolution enhancement by segmented correlation does reduce the spectral width of the input tone in the desired manner, but the signal power due to the input increases the variance of the spectral estimate near the input frequency, hindering accurate calculation of the in-band noise. This increased variance, which is predicted by theory, must be considered carefully in the application of segmented correlation. Methods for obtaining more accurate estimates of the quantization noise spectrum which are closer to those measured with no input are described.
Bulzacchelli, John F.; Lee, Hae-Seung; Hong, Merit Y.; Misewich, James A.; Ketchen, Mark B.
2003-12-01
Segmented correlation is a useful technique for testing a superconducting analogue-to-digital converter, as it allows the output spectrum to be estimated with fine frequency resolution even when data record lengths are limited by small on-chip acquisition memories. Previously, we presented segmented correlation measurements on a superconducting bandpass delta-sigma modulator sampling at 40.2 GHz under idle channel (no input) conditions. This paper compares the modulator output spectra measured by segmented correlation with and without an input tone. Important practical considerations of calculating segmented correlations are discussed in detail. Resolution enhancement by segmented correlation does reduce the spectral width of the input tone in the desired manner, but the signal power due to the input increases the variance of the spectral estimate near the input frequency, hindering accurate calculation of the in-band noise. This increased variance, which is predicted by theory, must be considered carefully in the application of segmented correlation. Methods for obtaining more accurate estimates of the quantization noise spectrum which are closer to those measured with no input are described.
Gao, Shanghua; Xue, Bing
2017-04-01
The dynamic range of the currently most widely used 24-bit seismic data acquisition devices is 10-20 dB lower than that of broadband seismometers, and this can affect the completeness of seismic waveform recordings under certain conditions. However, this problem is not easy to solve because of the lack of analog to digital converter (ADC) chips with more than 24 bits in the market. So the key difficulties for higher-resolution data acquisition devices lie in achieving more than 24-bit ADC circuit. In the paper, we propose a method in which an adder, an integrator, a digital to analog converter chip, a field-programmable gate array, and an existing low-resolution ADC chip are used to build a third-order 16-bit oversampling delta-sigma modulator. This modulator is equipped with a digital decimation filter, thus forming a complete analog to digital converting circuit. Experimental results show that, within the 0.1-40 Hz frequency range, the circuit board's dynamic range reaches 158.2 dB, its resolution reaches 25.99 dB, and its linearity error is below 2.5 ppm, which is better than what is achieved by the commercial 24-bit ADC chips ADS1281 and CS5371. This demonstrates that the proposed method may alleviate or even solve the amplitude-limitation problem that broadband observation systems so commonly have to face during strong earthquakes.
Experimental evaluation of a digitized fiber-wireless system employing sigma delta modulation.
Pessoa, Luis M; Coelho, Diogo; Salgado, Henrique M
2014-07-14
Digitized radio-over-fiber (D-RoF) transport schemes are being pointed as viable alternative solutions to their analog counterparts, in order to avoid distortion/dynamic range problems. Here we propose a novel D-RoF architecture that takes advantage of a bandpass sigma-delta modulator at the transmitter which subsequently permits the usage of a simpler/cheaper base station that avoids the employment of a digital to analog converter. The proposed architecture exploits the properties of the digital signal to enable the extraction of an higher carrier frequency through the employment of a bandpass filter. Furthermore, we present a comprehensive analysis regarding the impact of a low-cost electro-optic modulation on the quality of received demodulated signal. Finally, a comparison performance analysis between the conventional D-RoF and the proposed architecture is presented. We conclude that although the proposed architecture performs similarly to conventional D-RoF schemes, it is more competitive for either upgrading installed systems as well as for new deployments.
Multibit sigma-delta modulator with reduced sensitivity to DAC nonlinearity
Hairapetian, A.; Zhang, Z. X.; Temes, G. C.
1991-01-01
A new architecture is presented for a multibit oversampled Sigma-Delta A/D convertor. A novel feedback arrangement is employed to reduce the sensitivity of the overall resolution to the nonlinearity of the multibit DAC. Simulations confirm the improved performance achieved by the proposed structure.
分片旋转的Sigma-Delta模型的全局吸引子%Global Attraction in the Piecewise Rotation of the Sigma-Delta Modulator
Institute of Scientific and Technical Information of China (English)
余荣忠; 傅新楚; 袁利国
2005-01-01
This paper presents a complete proof of a conjecture given by Ashwin, Deane and Fu that the map describing the dynamical behavior of the Sigma-Delta modulator has a global attractor. By viewing the map as a piecewise rotation, and by geometric analysis,the authors give a simpler and more sufficient proof of the conjecture, than the one presented by Deane and published in Dynamical Systems, 2002,17: 377 - 388.
Genetic Algorithm for the Design of Electro-Mechanical Sigma Delta Modulator MEMS Sensors
Directory of Open Access Journals (Sweden)
Michael Kraft
2011-09-01
Full Text Available This paper describes a novel design methodology using non-linear models for complex closed loop electro-mechanical sigma-delta modulators (EMΣΔM that is based on genetic algorithms and statistical variation analysis. The proposed methodology is capable of quickly and efficiently designing high performance, high order, closed loop, near-optimal systems that are robust to sensor fabrication tolerances and electronic component variation. The use of full non-linear system models allows significant higher order non-ideal effects to be taken into account, improving accuracy and confidence in the results. To demonstrate the effectiveness of the approach, two design examples are presented including a 5th order low-pass EMΣΔM for a MEMS accelerometer, and a 6th order band-pass EMΣΔM for the sense mode of a MEMS gyroscope. Each example was designed using the system in less than one day, with very little manual intervention. The strength of the approach is verified by SNR performances of 109.2 dB and 92.4 dB for the low-pass and band-pass system respectively, coupled with excellent immunities to fabrication tolerances and parameter mismatch.
Comparisons of Feed-Forward and Multiple-Feedback Sigma-Delta Modulators for MEMS Accelerometers
Directory of Open Access Journals (Sweden)
Meimei Zhang
2016-01-01
Full Text Available This paper investigates two different architectures of a 5th order electro-mechanical sigma-delta modulator: a feed-forward (FF architecture and a multiple-feedback (MF architecture. And a comparison was performed in terms of stability and noise shaping ability, sensitivities to parameter variances due to fabrication tolerances and loop gain, and nonlinearity in feedback force. Both architectures were modeled in Simulink and investigated at system level. The results show that: a both architectures are stable and achieve the similar noise floor level of -170dB within 250Hz in the ideal condition; b both architectures have good ability in fabrication tolerance; c the performance of the MF architecture will degrade heavily with the loop gain decreasing and become unstable if the loop gain beyond one optimal value, while the FF architecture is insensitive; d the FF architecture controls the proof mass well and achieves better SNDR, whereas the MF has a 56dB degradation in consideration of nonlinearity in feedback force.
Recent advances in the analysis, design and optimization of Digital Delta-Sigma Modulators
Kennedy, Michael Peter
Digital Delta-Sigma Modulators (DDSMs) are almost univerally used in integrated circuits for wireless communications and digital audio, particularly in fractional-N frequency synthesizers and oversampled digital-to-analog converters (DACs). A DDSM is a nonlinear dynamical system which reduces the wordlength of an oversampled digital signal without significantly degrading the SNR in the signal band. DDSMs can exhibit a number of behaviors that are characteristic of nonlinear dynamical systems such as oscillation, coexisting steady-state solutions, sensitivity to initial conditions, and sensitivity to the input. This paper explains the root cause of deterministic spurious and idle tones in DDSMs—short periodic cycles—and describes strategies to eliminate them. The use of a DDSM simplifies the design of analog circuitry in a mixed-signal system. By reducing the bus width in a prescribed way, a DDSM can also permit more efficient downstream digital signal processing—in terms of power and speed—with negligible degradation in performance.
Genetic algorithm for the design of electro-mechanical sigma delta modulator MEMS sensors.
Wilcock, Reuben; Kraft, Michael
2011-01-01
This paper describes a novel design methodology using non-linear models for complex closed loop electro-mechanical sigma-delta modulators (EMΣΔM) that is based on genetic algorithms and statistical variation analysis. The proposed methodology is capable of quickly and efficiently designing high performance, high order, closed loop, near-optimal systems that are robust to sensor fabrication tolerances and electronic component variation. The use of full non-linear system models allows significant higher order non-ideal effects to be taken into account, improving accuracy and confidence in the results. To demonstrate the effectiveness of the approach, two design examples are presented including a 5th order low-pass EMΣΔM for a MEMS accelerometer, and a 6th order band-pass EMΣΔM for the sense mode of a MEMS gyroscope. Each example was designed using the system in less than one day, with very little manual intervention. The strength of the approach is verified by SNR performances of 109.2 dB and 92.4 dB for the low-pass and band-pass system respectively, coupled with excellent immunities to fabrication tolerances and parameter mismatch.
A contribution to continuous-time quadrature bandpass sigma-delta modulators for low-IF receivers
Kim, Song-Bok
2009-01-01
This work presents the implementation of the continuous-time quadrature bandpass sigma-delta modulators (CT-QBP SDMs). CT-QBP SDMs is well suited for low-IF receivers due to some significant advantages over other implementations. Firstly, the possible design methodologies have been defined and compared. The proposed inverse method is desirable for the design of CT-QBP SDM. Starting from CT loop filter optimization, the equivalent noise shaping transfer function is finally calculated and its s...
Binjie, Ge; Xin'an, Wang; Xing, Zhang; Xiaoxing, Feng; Qingqin, Wang
2010-01-01
The quantization noise leakage of the first stage in a MASH21 sigma-delta modulator is analyzed. The results show that the finite DC gain of the opamp is the main reason for noise leakage, and finite GBW and SR only generate harmonic distortion. The relationship between DC gain and leakage is modeled and conclusions on design criteria are reached. As an example, a MASH21 modulator for a digital audio application is realized. This modulator, fabricated in an 0.18 μm mixed signal process, achieves an SNDR of 91 dB with 1.8 V supply, which verifies the analysis and design criteria.
Multi-Bit Sigma-Delta Modulators with Enhanced Dynamic Range using Non-Linear DAC for Hearing Aids
DEFF Research Database (Denmark)
Custòdio, José; Paulino, Nuno; Goes, João
2008-01-01
This paper presents the possibility of employing non-linear low-resolution DACs in the feedback paths of multi-bit second-order Sigma-Delta modulators. The proposed technique is particularly attractive in applications such as hearing aids, requiring a very large dynamic range and medium signal......-to-noise-plus-distortion-ratio. As demonstrated through simulated results in which noise and mismatch effects are included, for the same over-sampling ratio, improvements in the order of 6-to-9 dB in the dynamic range can be achieved when comparing with the same topology employing linear-DACs....
Design of Low Power Sigma Delta ADC
Directory of Open Access Journals (Sweden)
Mohammed Arifuddin Sohel
2012-08-01
Full Text Available A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC filter is proposed. The second order modulator is designed to work at a signal band of 20 K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18 micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a total power 1.96mW.
Design of Low Power Sigma Delta ADC
Directory of Open Access Journals (Sweden)
Mohammed Arifuddin Sohel
2012-09-01
Full Text Available A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a total power 1.96mW.
运放和比较器共享的双通道Sigma-Delta调制器%Double-Channel Sigma-Delta Modulator with Opamp and Comparator Sharing
Institute of Scientific and Technical Information of China (English)
余有芳
2014-01-01
提出了一个低功耗的双通道Sigma-Delta调制器，利用运放和比较器共享的技术，实现了功耗的减半。相比于普通的运放共享技术，本文提出的方法消除了通道间的串扰。根据分析，前馈结构的双通道调制器可以使用普通的运放共享技术，而没有通道间串扰的问题。仿真结果验证了这些分析。%This paper presents a low-power double-channel sigma-delta modulator which features current consumption halved by opamp and comparator sharing. Compared to the common opamp sharing technique, the proposed method eliminates the cross interfere between channels. An alternative modulator architecture using common opamp sharing technique without cross interfere is analysed. The simulation results validate these analyses.
An 11 mW 79 dB DR {Delta}{Sigma} modulator for ADSL applications
Energy Technology Data Exchange (ETDEWEB)
Zhu Yingjia; Li Dongmei [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China); Liu Liyuan, E-mail: syj03@mails.tsinghua.edu.c [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)
2009-10-15
This paper shows the design of a second-order multi-bit {Delta}{Sigma} modulator with hybrid structure for ADSL applications. A modified two phase non-overlapping clock generator is designed to let PH2 borrow 12% of the time from PH1, which relaxes the speed of OTAs, comparators and the DEM block. The clock feed through problem of the passive adder is solved by revising the timing of the comparators and the adder. The chip is designed and fabricated in UMC 0.18 {mu}m CMOS technology. Measurement results show that with an oversampling ratio of 32 and a clock rate of 80 MHz, the modulator can achieve 79 dB dynamic range, 71.3 dB SNDR, 11 mW power consumption from a 1.8 V power supply. The FOM is 1.47 pJ/step.
A 1.1 mW 87 dB dynamic range {Delta} {sigma} modulator for audio applications
Energy Technology Data Exchange (ETDEWEB)
Liu Liyuan; Wang Zhihua; Wei Shaojun [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China); Chen Liangdong; Li Dongmei, E-mail: lidmei@tsinghua.edu.c [Department of Electronic Engineering, Tsinghua University, Beijing 100084 (China)
2010-05-15
This paper presents a 1.1 mW 87 dB dynamic range third order {Delta} {sigma} modulator implemented in 0.18 {mu}m CMOS technology for audio applications. By adopting a feed-forward multi-bit topology, the signal swing at the output of the first integrator can be suppressed. A simple current mirror single stage OTA with 34 dB DC gain working under 1 V power supply is used in the first integrator. The prototype modulator achieves 87 dB DR and 83.8 dB peak SNDR across the bandwidth from 100 Hz to 24 kHz with 3 kHz input signal. (semiconductor integrated circuits)
A 100-MHz bandpass sigma-delta modulator with a 75-dB dynamic range for IF receivers
Energy Technology Data Exchange (ETDEWEB)
Yuan Yudan; Li Li; Chang Hong; Guo Yawei; Cheng Xu; Zeng Xiaoyang, E-mail: 082052025@fudan.edu.cn, E-mail: chengxu@fudan.edu.cn [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)
2011-02-15
A fourth-order switched-capacitor bandpass {Sigma}{Delta} modulator is presented for digital intermediate-frequency (IF) receivers. The circuit operates at a sampling frequency of 100 MHz. The transfer function of the resonator considering nonidealities of the operational amplifier is proposed so as to optimize the performance of resonators. The modulator is implemented in a 0.13-{mu}m standard CMOS process. The measurement shows that the signal-to-noise-and-distortion ratio and dynamic range achieve 68 dB and 75 dB, respectively, over a bandwidth of 200 kHz centered at 25 MHz, and the power dissipation is 8.2 mW at a 1.2 V supply. (semiconductor integrated circuits)
不确定Sigma-Delta调制器的鲁棒滤波%Robust filtering for uncertain Sigma-Delta modulators
Institute of Scientific and Technical Information of China (English)
王英俊; 王武; 王骞
2013-01-01
研究级联Sigma-Delta调制器在非理想性电路中的鲁棒校正滤波器设计问题.基于MARKOV区间算法和线性区间系统的等价描述,将扰动抑制问题转化为增广系统的鲁棒稳定问题.给出以线性矩阵不等式描述的鲁棒滤波器存在的充分条件,该条件保证所设计的校正滤波器能有效抑制电路不确定性对调制器性能的影响.仿真结果表明,与传统校正滤波器相比,该调制器获得了更好的信号噪声比.方案降低了电路实现过程中器件精确度的要求,从而达到低应用成本的目的.%The design of robust correction filter for cascaded Sigma - Delta modulators with analog circuit imperfection is studied. Based on MARKOV interval algorithm and the equivalent description of linear interval system, the problem related to disturbance suppression is transformed into a robust stability problem. A linear matrix inequality approach is developed to obtain the parameters of a robust filter, which guarantees that the correction filter can effectively suppress the influence of analog circuit imperfection to the modulators. Simulation results show that the modulators exhibit lower variation in the signal - to - noise and distortion ratio over the nominal correction filter. The proposed scheme decreases requirements of accuracy during the circuit implementation, then achieve the purpose of low cost application.
Ito, Yuji; Doki, Shinji; Okuma, Sigeru
1-bit signal processing based on delta-sigma modulation has been studied for hardware implementation of signal processng systems. In the 1-bit signal processing, finite word-length problems such as overflow and coefficent quantization error occur. To solve the problems, new design method with state space is proposed in this paper. Digital filters are designed to show the feasibility of the method. Firstly, L1/L2-sensitivity is shown to evaluate coefficient quantization error and L2 scaling constraints to prevent overflow. Secondly, state space equation is shown and L1/L2-sensitivity and L2-scaling constraints are extended to take filter structure and oversampling effects into account. Finally, the proposed method is shown to attain higher SNR than conventional ones.
Performance evaluation of photonic Sigma Delta ADCS
Tan, Yean Wee
2010-01-01
Approved for public release; distribution is unlimited The integration of photonic and electronic components to realize a photonic sigma delta ADC is considered in this thesis. The integration process was broken up into steps. First, the performance of a pair of dual-port Mach-Zehnder interferometers (MZI) modulating a train of narrow high-speed laser pulses from a mode-locked laser was investigated. Various parameters like the half-wave voltage (V) and insertion loss were verified. Nex...
A Simple Signal Shaper for GMSK/GFSK and MSK Modulator Based on Sigma-Delta Look-up Table
Directory of Open Access Journals (Sweden)
T. Svedek
2009-06-01
Full Text Available Due to wide power spectrums of rectangular data streams, it is important for base-band signals to be heavily band limited before modulation. That can be achieved by pulse shaping of rectangular bits. Some of the most common are a half-sine pulse shaper and a Gaussian pulse shaper which are used in Minimum Shift Keying (MSK, Gaussian Minimum Shift Keying (GMSK and Gaussian Frequency Shift Keying (GFSK modulations, respectively. The most common solutions of such shapers use PCM based look-up-table (LUT, which requires an nbit D/A converter. We proposed the use of a 1-bit Sigma Delta Modulation (SDM LUT, which results in smaller ROM capacity, a 1-bit wide output word, and a simple1-bit D/A converter realized as an out-of-chip first-order lowpass RC filter, or an in-chip charge pump. This article describes a simple, but efficient SDM LUT-based half-sine and Gaussian shaper that can be used for generation of MSK and GMSK/GFSK modulated signals. Oscillograms and power spectrums are measured on SDM LUT realized in FLEX AlteraTM PLD, for a 10-bit pseudo-noise sequence test input signal.
低电源电压超低功耗Delta-Sigma调制器%Low voltage ultra-low power delta-sigma modulator
Institute of Scientific and Technical Information of China (English)
赵津晨; 赵梦恋; 吴晓波
2013-01-01
为了在低电源电压约束下实现delta-sigma模数转换器(ADC)的低功耗与高精度设计,提出基于开关型运放以及新颖DWA技术的delta-sigma调制器.其中的开关型运放仅工作于半周期相位,可以在低于1V的电源电压下正常工作,节省了系统功耗.调制器的积分器采用运放分享技术,以降低硬件开销.采用双向循环移位数据加权平均(DCS-DWA)技术,在抑制调制回路中匹配单元误差引起的非线性失真的同时消除了与输入信号相关的寄生音调,提高系统分辨率.提出的delta-sigma调制器在SMIC 0.18 μm 1P6M工艺下流片,动态范围与峰值SNDR分别达94.6和92.5 dB,芯片面积为0.72 mm2.在0.9V电源电压下,测得系统功耗仅为56 μW,品质因数(FoM)低至34.2 fJ/c-step.结果表明,预期的主要设计目标均已实现.%A switched-opamp (SO) based delta-sigma modulator with novel data weighted averaging (DWA) technique was presented in order to achieve a high resolution low power consumption delta-sigma analog-to-digital converter (ADC) under the constraint of low supply voltage.The proposed SO structure operated only during a half clock phase under a sub-1 V supply voltage,which effectively reduced the power consumption of the system.The opamp-shared technique was applied to save the hardware overhead.Due to the use of dual cycle shift data weighted averaging (DCS-DWA) technique,the nonlinear distortion caused by units mismatch in the feedback loop of the modulator was removed without introducing signaldependent tones,so that the resolution of the system could be improved.The proposed delta-sigma modulator was implemented in a SMIC 0.18 μm 1P6M process.The measured dynamic range and peak signal to noise and distortion ratio (SNDR) were 94.6 dB and 92.5 dB,respectively,and the core area of the modulator was 0.72 mm2.The total power consumption was 56μW when a 0.9 V supply voltage was provided,and the figure-of-merit (FoM) was only 34.2 f
Ruck, B.; Chong, Y.; Dittmann, R.; Engelhardt, A.; Sodtke, E.; Siegel, M.
1999-11-01
We have designed, fabricated and successfully tested a first-order delta-sigma modulator using a high-temperature superconducting multilayer technology with bicrystal Josephson junctions. The circuit has been fabricated on a SrTiO3 bicrystal substrate. The YBa2Cu3O7/SrTiO3/YBa2Cu3O7 trilayer was fabricated by laser deposition. The bottom layer served as a superconducting groundplane. The Josephson junctions were formed at the bicrystal line in the upper layer. The integrator resistance has been made from a Pd/Au thin film. The circuit consists of a dc-SFQ converter, a Josephson transmission line, a comparator, an L/R integrator and an output stage. The correct operation of the modulator has been tested using dc measurements. The linearity of the modulator was studied by measuring the harmonic distortions of a 19.5 kHz sine wave input signal. From the recorded spectrum, a minimum resolution of at least 5 bits can be estimated. This accuracy was limited by the noise of the preamplifier. The correct operation of the current feedback loop was demonstrated by cutting the feedback inductance.
Energy Technology Data Exchange (ETDEWEB)
Ruck, B.; Chong, Y.; Dittmann, R.; Engelhardt, A.; Sodtke, E.; Siegel, M. [Institut fur Schicht- und Ionentechnik (ISI), Forschungszentrum Julich GmbH, 52425 Juelich (Germany)
1999-11-01
We have designed, fabricated and successfully tested a first-order delta-sigma modulator using a high-temperature superconducting multilayer technology with bicrystal Josephson junctions. The circuit has been fabricated on a SrTiO{sub 3} bicrystal substrate. The YBa{sub 2}Cu{sub 3}O{sub 7}/SrTiO{sub 3}/YBa{sub 2}Cu{sub 3}O{sub 7} trilayer was fabricated by laser deposition. The bottom layer served as a superconducting ground plane. The Josephson junctions were formed at the bicrystal line in the upper layer. The integrator resistance has been made from a Pd/Au thin film. The circuit consists of a dc-SFQ converter, a Josephson transmission line, a comparator, an L/R integrator and an output stage. The correct operation of the modulatorhas been tested using dc measurements. The linearity of the modulator was studied by measuring the harmonic distortions of a 19.5 kHz sine wave input signal. From the recorded spectrum, a minimum resolution of at least 5 bits can be estimated. This accuracy was limited by the noise of the preamplifier. The correct operation of the current feedback loop was demonstrated by cutting the feedback inductance. (author)
An integrated delta-sigma based IIR filter
Au, Dennis Kin-Wah
Delta-sigma based infinite impulse response (IIR) filters are a recently developed circuit technique for efficiently realizing IIR filters operating directly on oversampled delta-sigma modulated signals. The design and single-chip implementation of a fifth-order delta-sigma based IIR filter are described. The filter coefficients are fully programmable and with the use of a structure that is inherently scaled for dynamic range, good filter performance is maintained over a wide variety of transfer functions. To eliminate multi-bit multiplications, five second-order digital delta-sigma modulators were used and dynamic range improvement was obtained through the use of multi-bit quantizers in these modulators. The filter was implemented as a very large scale integration chip using 1.2 micron complementary metal oxide semiconductor technology, occupying an area of 4,355 by 5,962 square microns. Simulations indicate that the clock range should operate up to 45 MHz.
Vilain, J. P.; Lesbroussart, Ch.
1995-07-01
In this paper, the authors propose a new strategy for the command of the three-phase voltage inverter's switches. After a recall of the principle on which the Delta-Sigma modulation single-phase converter works, they emphasize the avantages it provides and they show how this strategy can be extended to the three-phase voltage inverter by a vectorial approach. Compared to usual modulations and space vector modulation techniques that are now frequently to be found, for identical average switching frequency, this process improves the quality of the output voltages applied to the load. The numerical simulation results are presented. Dans cet article, les auteurs proposent une nouvelle stratégie de commande des interrupteurs d'un onduleur de tension triphasé. Après avoir rappelé le principe de la modulation Delta Sigma utilisée pour les convertisseurs monophasés, et souligné les avantages qu'elle apporte, ils montrent comment cette stratégie peut être étendue au cas de l'onduleur de tension triphasé par une approche vectorielle. Par rapport aux modulations classiques et aux techniques de “Modulation du Vecteur d'Espace", que l'on rencontre aujourd'hui fréquemment et pour une fréquence moyenne de commutation identique, ce procédé améliore la “qualité" des tensions de sortie appliquées à la charge. Les résultats de la simulation numérique sont présentés.
A 8X Oversampling Ratio, 14bit, 5-MSamples/s Cascade 3-1 Sigma-delta Modulator
Directory of Open Access Journals (Sweden)
Y. Yin
2005-01-01
Full Text Available A 14-b, 5-MHz output-rate cascaded 3-1 sigma-delta analog-to-digital converters (ADC has been developed for broadband communication applications, and a novel 4th-order noise-shaping is obtained by using the proposed architecture. At a low oversampling ratio (OSR of 8, the ADC achieves 91.5dB signal-to-quantization ratio (SQNR, in contrast to 71.8dB of traditional 2-1-1 cascaded sigma-delta ADC in 2.5-MHz bandwidth and over 80dB signal-to-noise and distortion (SINAD even under assumptions of awful circuit non-idealities and opamp non-linearity. The proposed architecture can potentially operates at much more high frequencies with scaled IC technology, to expand the analog-to-digital conversion rate for high-resolution applications.
A 8X Oversampling Ratio, 14bit, 5-MSamples/s Cascade 3-1 Sigma-delta Modulator
Yin, Y.; Klar, H.; Wennekers, P.
2005-05-01
A 14-b, 5-MHz output-rate cascaded 3-1 sigma-delta analog-to-digital converters (ADC) has been developed for broadband communication applications, and a novel 4th-order noise-shaping is obtained by using the proposed architecture. At a low oversampling ratio (OSR) of 8, the ADC achieves 91.5dB signal-to-quantization ratio (SQNR), in contrast to 71.8dB of traditional 2-1-1 cascaded sigma-delta ADC in 2.5-MHz bandwidth and over 80dB signal-to-noise and distortion (SINAD) even under assumptions of awful circuit non-idealities and opamp non-linearity. The proposed architecture can potentially operates at much more high frequencies with scaled IC technology, to expand the analog-to-digital conversion rate for high-resolution applications.
System Level Design of a Continuous-Time Delta-Sigma Modulator for Portable Ultrasound Scanners
DEFF Research Database (Denmark)
Llimos Muntal, Pere; Færch, Kjartan; Jørgensen, Ivan Harald Holger;
2015-01-01
In this paper the system level design of a continuous-time ∆Σ modulator for portable ultrasound scanners is presented. The overall required signal-to-noise ratio (SNR) is derived to be 42 dB and the sampling frequency used is 320 MHz for an oversampling ratio of 16. In order to match these requir......, based on high-level VerilogA simulations, the performance of the ∆Σ modulator versus various block performance parameters is presented as trade-off curves. Based on these results, the block specifications are derived....
Design of low power and low area passive sigma delta modulators for audio applications
Fouto, David
2017-01-01
This book presents the study, design, modulation, optimization and implementation of low power, passive DT-ΣΔMs for use in audio applications. The high gain and bandwidth amplifier normally used for integration in ΣΔ modulation, is replaced by passive, switched-capacitor branches working under the Ultra Incomplete Settling (UIS) condition, leading to a reduction of the consumed power. The authors describe a design process that uses high level models and an optimization process based in genetic algorithms to achieve the desired performance.
System Level Design of a Continuous-Time Delta-Sigma Modulator for Portable Ultrasound Scanners
DEFF Research Database (Denmark)
Llimos Muntal, Pere; Færch, Kjartan; Jørgensen, Ivan Harald Holger
2015-01-01
In this paper the system level design of a continuous-time ∆Σ modulator for portable ultrasound scanners is presented. The overall required signal-to-noise ratio (SNR) is derived to be 42 dB and the sampling frequency used is 320 MHz for an oversampling ratio of 16. In order to match these requir......In this paper the system level design of a continuous-time ∆Σ modulator for portable ultrasound scanners is presented. The overall required signal-to-noise ratio (SNR) is derived to be 42 dB and the sampling frequency used is 320 MHz for an oversampling ratio of 16. In order to match...... these requirements, a fourth order, 1-bit modulator with optimal zero placing is used. An analysis shows that the thermal noise from the resistors and operational transconductance amplifier is not a limiting factor due to the low required SNR, leading to an inherently very low-power implementation. Furthermore......, based on high-level VerilogA simulations, the performance of the ∆Σ modulator versus various block performance parameters is presented as trade-off curves. Based on these results, the block specifications are derived....
Non-Inverted Buck-Boost Converters with Dual Delta Sigma Modulators
Kobori, Yasunori; Kono, Masashi; Shimizu, Toshihiko; Kobayashi, Haruo
This paper presents a new control circuit to create high-performance non-inverted Buck-Boost converter with dual ⊿∑ modulations. Experimental load regulation, corresponding to load current steps of ±0.5A, is within 45mVpp, and the efficiency without synchronized rectifier is 83% at input voltage 2.5V and load current 0.8A.
Kaneko, Nobu-hisa; Maruyama, Michitaka; Urano, Chiharu; Kiryu, Shogo
2012-01-01
A method of AC waveform synthesis with quantum-mechanical accuracy has been developed on the basis of the Josephson effect in national metrology institutes, not only for its scientific interest but its potential benefit to industries. In this paper, we review the development of Josephson arbitrary waveform synthesizers based on the two types of Josephson junction array and their distinctive driving methods. We also discuss a new operation technique with multibit delta-sigma modulation and a thermometer code, which possibly enables the generation of glitch-free waveforms with high voltage levels. A Josephson junction array for this method has equally weighted branches that are operated by thermometer-coded bias current sources with multibit delta-sigma conversion.
Reconfigurable Bandpass Sigma-Delta Modulator With Programmable NTF for Low-IF Multi-Mode Receivers
DEFF Research Database (Denmark)
Zhang, Ke; Mikkelsen, Jan H.; Shen, Ming
2012-01-01
A new reconfigurable bandpass sigma–delta modulator (BPSDM) structure is proposed for low-IF multi-mode wireless systems. The proposed modulator can be reconfigured to operate in different signal bandwidths and at different signal-to-noise ratios by rearranging and optimizing the order of the noise...
A 1-V 60-{mu}W 85-dB dynamic range continuous-time third-order sigma-delta modulator
Energy Technology Data Exchange (ETDEWEB)
Li Yuanwen; Qi Da; Dong Yifeng; Xu Jun; Ren Junyan, E-mail: 072021068@fudan.edu.c [State Key Laboratory of ASIC and System, Shanghai 201203 (China)
2009-12-15
A 1-V third order one-bit continuous-time (CT) EA modulator is presented. Designed in the SMIC mixed-signal 0.13-{mu}m CMOS process, the modulator utilizes active RC integrators to implement the loop filter. An efficient circuit design methodology for the CT {Sigma}{Delta} modulator is proposed and verified. Low power dissipation is achieved through the use of two-stage class A/AB amplifiers. The presented modulator achieves 81.4-dB SNDR and 85-dB dynamic range in a 20-kHz bandwidth with an over sampling ratio of 128. The total power consumption of the modulator is only 60 {mu}W from a 1-V power supply and the prototype occupies an active area of 0.12 mm{sup 2}. (semiconductor integrated circuits)
Institute of Scientific and Technical Information of China (English)
严博; 曾韡; 高峰
2009-01-01
研究一种基于非延时积分器Delta-Sigma调制的差分电容探测接口电路,该电路的Delta-Sigma调制使用非延时积分器将采样与积分同时进行,减小普通Delta-Sigma调制型电容探测电路中积分保持阶段的电荷泄露效应,仿真结果表明该结构可明显提高探测较小电容的信噪比,增加了调制器可探测电容的动态范围.%This paper introduces a Delta-Sigma modulator with non-delay integrator for capacitance detection, which reduces the leak charge by integrating and sampling simultaneously instead of taking them separately in most occasions. This structure can greatly improve the performance of Delta-Sigma modulator u-sing in small capacitance detection. The end of this paper shows the simulation results of a 2nd order modulation which achieve a great increase ability in detecting SNR(Signal to Noise Ratio) for ultra small capacitance and a larger dynamic range in application.
Kaald, Rune; Eggen, Trym; Ytterdal, Trond
2017-02-01
Fully digitized 2D ultrasound transducer arrays require one ADC per channel with a beamforming architecture consuming low power. We give design considerations for per-channel digitization and beamforming, and present the design and measurements of a continuous time delta-sigma modulator (CTDSM) for cardiac ultrasound applications. By integrating a mixer into the modulator frontend, the phase and frequency of the input signal can be shifted, thereby enabling both improved conversion efficiency and narrowband beamforming. To minimize the power consumption, we propose an optimization methodology using a simulated annealing framework combined with a C++ simulator solving linear electrical networks. The 3rd order single-bit feedback type modulator, implemented in a 65 nm CMOS process, achieves an SNR/SNDR of 67.8/67.4 dB across 1 MHz bandwidth consuming 131 [Formula: see text] of power. The achieved figure of merit of 34.2 fJ/step is comparable with state-of-the-art feedforward type multi-bit designs. We further demonstrate the influence to the dynamic range when performing dynamic receive beamforming on recorded delta-sigma modulated bit-stream sequences.
A Low Distortion 3rd-Order Continuous-Time Delta-Sigma Modulator for a Worldwide Digital TV-Receiver
Obata, Koji; Matsukawa, Kazuo; Mitani, Yosuke; Takayama, Masao; Tokunaga, Yusuke; Sakiyama, Shiro; Dosho, Shiro
This paper presents a low distortion 3rd-order continuous-time delta-sigma modulator for a worldwide digital TV-receiver whose peak SNDR is 69.8dB and SNR is 70.2dB under 1V power supply. To enhance SNDR performance, the mechanisms to occur harmonic distortions at feedback current-steering DAC and flash ADC have been analyzed. A low power tuning system using RC-relaxation oscillator has been developed in order to achieve high yield against PVT variations. A 3rd-order modulator with modified single opamp resonator contributes to cost reduction by realizing a very compact circuit. Reduction schemes of the distortions enabled the modulator to achieve FOM of 0.18pJ/conv-step.
Okcan, Burak; Gielen, Georges; Van Hoof, Chris
2012-02-01
This paper presents a third-order switched-capacitor sigma-delta modulator implemented in a standard 0.35-μm CMOS process. It operates from 300 K down to 4.2 K, achieving 70.8 dB signal-to-noise-plus-distortion ratio (SNDR) in a signal bandwidth of 5 kHz with a sampling frequency of 500 kHz at 300 K. The modulator utilizes an operational transconductance amplifier in its loop filter, whose architecture has been optimized in order to eliminate the cryogenic anomalies below the freeze-out temperature. At 4.2 K, the modulator achieves 67.7 dB SNDR consuming 21.17 μA current from a 3.3 V supply.
Nonlinearities in SC Delta-Sigma A/D Converters
DEFF Research Database (Denmark)
Steensgaard-Madsen, Jesper
1998-01-01
The effects of using nonlinear low-gain opamps in switched-capacitor delta-sigma modulators are analyzed. Using unconventional topologies, the state variables are made essentially uncorrelated with the input signal, hence opamp nonlinearity will cause very little harmonic distortion. Nonlinearity...
Periodicity in Delta-modulated feedback control
Institute of Scientific and Technical Information of China (English)
Xiaohua XIA; Guanrong CHEN; Rudong GAI; Alan S. I. ZINOBER
2008-01-01
The Delta-modulated feedback control of a linear system introduces nonlinearity into the system through switchings between two input values. It has been found that Delta-modulation gives rise to periodic orbits. The existence of periodic points of all orders of Sigma-Delta modulation with "leaky" integration is completely characterized by some interesting groups of polynomials with "sign" coefficients. The results are naturally generalized to Sigma-Delta modulations with multiple delays, Delta-modulations in the "downlink", unbalanced Delta-modulations and systems with two-level quantized feedback. Further extensions relate to the existence of periodic points arising from Delta-modulated feedback control of a stable linear system in an arbitrary direction, for which some necessary and sufficient conditions are given.
Directory of Open Access Journals (Sweden)
R. Silva-Ortigoza
2014-01-01
Full Text Available Sliding mode control is a discontinuous control technique that is, by its nature, appropriate for controlling variable structure systems, such as the switch regulated systems employed in power electronics. However, when designing control laws based on the average models of these systems a modulator is necessary for their experimental implementation. Among the most widely used modulators in power electronics are the pulse width modulation (PWM and, more recently, the sigma-delta-modulator (Σ-Δ-modulator. Based on the importance of achieving an appropriate implementation of average control laws and the relevance of the trajectory tracking task in DC/DC power converters, for the first time, this research presents the assessment of the experimental results obtained when one of these controllers is implemented through either a PWM or a Σ-Δ-modulator to perform such a task. A comparative assessment based on the integral square error (ISE index shows that, at frequencies with similar efficiency, the Σ-Δ-modulator provides a better tracking performance for the DC/DC Buck converter. In this paper, an average control based on differential flatness was used to perform the experiments. It is worth mentioning that a different trajectory tracking controller could have been selected for this research.
Bandpass Delta Sigma A/D convertor using two-path multibit structure
Zhang, Z. X.; Temes, G. C.; Czarnul, Z.
1991-10-01
The concept of an N-path bandpass Delta Sigma A/D convertor is introduced. A multibit sixth-order SC implementation is described. The new scheme appears to be very effective for the realization of the narrowband bandpass delta-sigma modulators needed for communication applications.
Institute of Scientific and Technical Information of China (English)
王淳; 谢妮慧; 林喆
2014-01-01
在目前的空间指向镜位置伺服系统中，数字控制器输出脉宽调制（PWM）的量化误差会导致指向出现小幅角度振荡，使得指向的稳定性降低，进而导致光学遥感成像质量发生退化。针对航天器工程实现的特点，将 Delta-Sigma 调制器引入到数控软件中，在不改变硬件电路与系统参数的前提下，显著的降低了输出量化误差对伺服系统的影响。Matlab仿真结果表明，该方法可使指向镜的指向角度振荡幅值衰减至原来的1/5以下，有效地提高了指向镜的指向稳定性。%The quantization error of DPWM causes slight angle oscillation and stability decrease in pointer mirror position servo system, which results in degradation of optical imaging quality in space remote sensor. On the premise of changing no circuit and system parameters, Delta-Sigma modulator is applied to the software of products in this paper, which significantly lessens the impact of DPWM quantization error on the servo system. A Matlab simulation of pointer mirror position servo system is presented, with the result of more than 5 times attenuation of the amplitude of the angle oscillation by using Delta-Sigma modulator.
基于Verilog-A的Sigma Delta系统行为级建模%Sigma Delta Modulators Behavioral Modeling Based on Verilog-A
Institute of Scientific and Technical Information of China (English)
倪劼; 姚建楠
2009-01-01
介绍Verilog-A设计语言的特点,基于Sigma Delta系统介绍分级设计思想.分析开关电容型Sigma Delta调制器的非理想特性,主要包括时钟抖动、开关热噪声、运放增益、摆率等.在建立各自噪声模型的基础上,基于Verilog-A对二阶Sigma Delta系统行为级完整建模,通过仿真结果的比对,验证Verilog-A建模,总结其可准确预测指标并在一定程度上有效地削减仿真时间的优点.
Understanding delta-sigma data converters
Pavan, Shanti; Temes, Gabor C
2017-01-01
This new edition introduces novel analysis and design techniques for delta-sigma (ΔΣ) converters in physical and conceptual terms, and includes new chapters that explore developments in the field over the last decade. This book explains the principles and operation of delta-sigma analog-to-digital converters (ADCs) in physical and conceptual terms in accordance with the most recent developments in the field. The interest of ΔΣ converter designers has shifted significantly over the past decade, due to many new applications for data converters at the far ends of the frequency spectrum. Continuous-time delta-sigma A/D converters with GHz clocks, of both lowpass and bandpass types, are required for wireless applications. At the other extreme, multiplexed ADCs with very narrow (sometimes 10 Hz wide) signal bandwidths, but very high accuracy are needed in the interfaces of biomedical and environmental sensors. To reflect the changing eeds of designers, the second edition includes significant new material on bo...
Dei, Michele; Sutula, Stepan; Cisneros, Jose; Pun, Ernesto; Jansen, Richard Jan Engel; Terés, Lluís; Serra-Graells, Francisco
2017-01-01
Infrared imaging technology, used both to study deep-space bodies’ radiation and environmental changes on Earth, experienced constant improvements in the last few years, pushing data converter designers to face new challenges in terms of speed, power consumption and robustness against extremely harsh operating conditions. This paper presents a 96.6-dB-SNDR (Signal-to-Noise-plus-Distortion Ratio) 50-kHz-bandwidth fourth-order single-bit switched-capacitor delta-sigma modulator for ADC operating at 1.8 V and consuming 7.9 mW fit for space instrumentation. The circuit features novel Class-AB single-stage switched variable-mirror amplifiers (SVMAs) enabling low-power operation, as well as low sensitivity to both process and temperature deviations for the whole modulator. The physical implementation resulted in a 1.8-mm2 chip integrated in a standard 0.18-μm 1-poly-6-metal (1P6M) CMOS technology, and it reaches a 164.6-dB Schreier figure of merit from experimental SNDR measurements without making use of any clock bootstrapping, analog calibration, nor digital compensation technique. When coupled to a 2048×2048 IR imager, the current design allows more than 50 frames per minute with a resolution of 16 effective number of bits (ENOB) while consuming less than 300 mW. PMID:28574466
Dei, Michele; Sutula, Stepan; Cisneros, Jose; Pun, Ernesto; Jansen, Richard Jan Engel; Terés, Lluís; Serra-Graells, Francisco
2017-06-02
Infrared imaging technology, used both to study deep-space bodies' radiation and environmental changes on Earth, experienced constant improvements in the last few years, pushing data converter designers to face new challenges in terms of speed, power consumption and robustness against extremely harsh operating conditions. This paper presents a 96.6-dB-SNDR (Signal-to-Noise-plus-Distortion Ratio) 50-kHz-bandwidth fourth-order single-bit switched-capacitor delta-sigma modulator for ADC operating at 1.8 V and consuming 7.9 mW ﬁt for space instrumentation. The circuit features novel Class-AB single-stage switched variable-mirror ampliﬁers (SVMAs) enabling low-power operation, as well as low sensitivity to both process and temperature deviations for the whole modulator. The physical implementation resulted in a 1.8-mm(2) chip integrated in a standard 0.18-µm 1-poly-6-metal (1P6M) CMOS technology, and it reaches a 164.6-dB Schreier ﬁgure of merit from experimental SNDR measurements without making use of any clock bootstrapping,analogcalibration,nordigitalcompensationtechnique. Whencoupledtoa2048×2048 IR imager, the current design allows more than 50 frames per minute with a resolution of 16 effective number of bits (ENOB) while consuming less than 300 mW.
一种新的带通Sigma-Delta调制器的设计%The Design of a New Band-Pass Sigma-Delta Modulator
Institute of Scientific and Technical Information of China (English)
程剑平; 魏同立
2005-01-01
设计了一种带宽为1.25MHz,中心频率为20MHz的带通Sigma-Delta调制器,提出了一种新的结构及其系数的计算方法,该结构的性能受系数变化的影响较小,其谐振器的输出摆幅也较小,因而降低了对运算放大器的设计要求.模拟结果表明:考虑各种非理想因素后,调制器的动态范围(DR)为60dB.
A high performance receiver using a subsampling mixer and Delta-Sigma ADC
小林,和也; Kobayashi, Kazuya
2012-01-01
In this paper, we propose a high performance receiver architecture for wireless communication systems, such as Bluetooth. This architecture uses a subsampling mixer and a delta-sigma modulator. The proposed sub-sampling mixer has complex band-pass characteristics. The band-pass filter suppresses the aliasing noise generated by the subsampling mixer. The proposed discrete time delta-sigma modulator has an up-conversion mixer and a down-conversion mixer. An intermediate frequency signal convert...
Interference Resilient Sigma Delta-Based Pulse Oximeter.
Shokouhian, Mohsen; Morling, Richard; Kale, Izzet
2016-06-01
Ambient light and optical interference can severely affect the performance of pulse oximeters. The deployment of a robust modulation technique to drive the pulse oximeter LEDs can reduce these unwanted effects and increases the resilient of the pulse oximeter against artificial ambient light. The time division modulation technique used in conventional pulse oximeters can not remove the effect of modulated light coming from surrounding environment and this may cause huge measurement error in pulse oximeter readings. This paper presents a novel cross-coupled sigma delta modulator which ensures that measurement accuracy will be more robust in comparison with conventional fixed-frequency oximeter modulation technique especially in the presence of pulsed artificial ambient light. Moreover, this novel modulator gives an extra control over the pulse oximeter power consumption leading to improved power management.
Heterodyning technique to improve performance of delta-sigma-based beamformers.
Freeman, S R; Quick, M K; Morin, M A; Anderson, R C; Desilets, C S; Linnenbrink, T E; O'Donnell, M
1999-01-01
Delta-sigma (DeltaSigma) modulators can implement a simpler digital ultrasound beamformer than can traditional architectures based on multi-bit analog-to-digital converters (A/D). The signal-to-noise ratio (SNR) of the DeltaSigma modulators, however, suffers from limited oversampling ratios. To improve the SNR of each channel, a mixing signal heterodynes narrowband signals to lower frequencies where the baseband DeltaSigma modulator performs better. Noise figure analyses are presented that illustrate the effectiveness of this technique in improving noise performance. Also, spectral Doppler and color flow simulations are presented that realistically emulate a 32 channel oversampled beamformer and compare these results with traditional and ideal systems.
Small-area decimators for delta-sigma video sensors
Azabache Villar, Erika; Skorka, Orit; Joseph, Dileepan
2014-04-01
A delta-sigma, or sigma-delta, analog-to-digital converter (ADC) comprises both a modulator, which implements oversampling and noise shaping, and a decimator, which implements low-pass filtering and downsampling. Whereas these ADCs are ubiquitous in audio applications, their usage in video applications is emerging. Because of oversampling, it is preferable to integrate delta-sigma ADCs at the pixel level of megapixel video sensors. Moreover, with pixel-level applications, area usage per ADC is much more important than with chip-level applications, where there is only one or a few ADCs per chip. Recently, a small-area decimator was presented that is suitable for pixel-level applications. However, though the pixel-level design is small enough for invisible-band video sensors, it is too large for visible-band ones. As shown here, nanoscale CMOS processes offer a solution to this problem. Given constant specifications, small-area decimators are designed, simulated, and laid out, full custom, for 180, 130, and 65nm standard CMOS processes. Area usage of the whole decimator is analyzed to establish a roadmap for the design and demonstrate that it could be competitive compared to other digital pixel sensors, based on Nyquist-rate ADCs, that are being commercialized.
Webb, Matthew; Tang, Hua
2016-08-01
In the past decade or two, due to constant and rapid technology changes, analog design re-use or design retargeting to newer technologies has been brought to the table in order to expedite the design process and improve time-to-market. If properly conducted, analog design retargeting could significantly cut down design cycle compared to designs starting from the scratch. In this article, we present an empirical and general method for efficient analog design retargeting by design knowledge re-use and circuit synthesis (CS). The method first identifies circuit blocks that compose the source system and extracts the performance parameter specifications of each circuit block. Then, for each circuit block, it scales the values of design variables (DV) from the source design to derive an initial design in the target technology. Depending on the performance of this initial target design, a design space is defined for synthesis. Subsequently, each circuit block is automatically synthesised using state-of-art analog synthesis tools based on a combination of global and local optimisation techniques to achieve comparable performance specifications to those extracted from the source system. Finally, the overall system is composed of those synthesised circuit blocks in the target technology. We illustrate the method using a practical example of a complex Delta-Sigma modulator (DSM) circuit.
Ninh, Hong Phuc; Miyahara, Masaya; Matsuzawa, Akira
This paper considers a simple type of Dynamic Element Matching (DEM), Clocked Averaging (CLA) method referred to as one-element-shifting (OES) and its effectiveness for the implementation of high spurious-free dynamic range (SFDR) multi-bit Delta-Sigma modulators (DSMs). Generic DEM techniques are successful at suppressing the mismatch error and increasing the SFDR of data converters. However, they will induce additional glitch energy in most cases. Some recent DEM methods achieve improvements in minimizing glitch energy but sacrificing their effects in harmonic suppression due to mismatches. OES technique discussed in this paper can suppress the effect of glitch while preserving the reduction of element mismatch effects. Hence, this approach achieves better SFDR performance over the other published DEM methods. With this OES, a 3rd order, 10MHz bandwidth continuous-time DSM is implemented in 90nm CMOS process. The measured SFDR attains 83dB for a 10MHz bandwidth. The measurement result also shows that OES improves the SFDR by higher than 10dB.
DEFF Research Database (Denmark)
Furst, Claus Efdmann
1996-01-01
-sampling ratio (OSR) of 128 and a sampling frequency of 1.28MHz. The very low power consumption is achieved by using a new type of efficient class AB amplifiers in a fully differential configuration. The modulator is implemented in a 0.7 micron n-well CMOS technology. Optimisation details concerning modulator...... coefficients and bias requirement of amplifiers is described....
Continuous time sigma delta ADC design and non-idealities analysis
Institute of Scientific and Technical Information of China (English)
Yuan Jun; Zhang Zhaofeng; Wu Jun; Wang Chao; Chen Zhenhai; Qian Wenrong; Yang Yintang
2011-01-01
A wide bandwidth continuous time sigma delta ADC is implemented in 130 nm CMOS.A detailed nonidealities analysis(excess loop delay,clock jitter,finite gain and GBW,comparator offset and DAC mismatch)is performed developed in Matlab/Simulink.This design is targeted for wide bandwidth applications such as video or wireless base-stations.A third-order continuous time sigma delta modulator comprises a third-order RC operationalamplifier-based loop filter and 3-bit internal quantizer operated at 512 MHz clock frequency.The sigma delta ADC achieves 60 dB SNR and 59.3 dB SNDR over a 16-MHz signal band at an OSR of 16.The power consumption of the CT sigma delta modulator is 22 mW from the 1.2-V supply.
Hotta, Hirohisa; Murahashi, Yoshimitsu; Doki, Shinji; Okuma, Shigeru
In order to ride on the strength of paralell operation a feature of neural network, it is preferable that all neuron is implemented on hardware. Formerly, we combine Neural Network and ΔΣ modulation, which is a method of converting to 1bit pulsed signal. Then we succeeded to configurate “a Pulsed Neural Network based on ΔΣ modulation(DSM-PNN)", which keep the circuit scale as same as to operate precisely. In last paper, we proposed hardware implementation methods of DSM-PNN with GHA learning rule and show its availability in linear operation. However, since neural networks are characterized by nonlinear map, signals needs to be treated with sufficient precision, also in nonlinear operation. In this paper, in order to shows that the 1-bit signal processing by DSM-PNN can be available, even when it includes nonlinear operation, we proposed the technique of realizing algorithm of ICA including nonlinear operation in DSM-PNN and confirm the performance of it.
Chen, Fang; Chang, Honglong; Yuan, Weizheng; Wilcock, Reuben; Kraft, Michael
2012-10-01
This paper describes a novel multiobjective parameter optimization method based on a genetic algorithm (GA) for the design of a sixth-order continuous-time, force feedback band-pass sigma-delta modulator (BP-ΣΔM) interface for the sense mode of a MEMS gyroscope. The design procedure starts by deriving a parameterized Simulink model of the BP-ΣΔM gyroscope interface. The system parameters are then optimized by the GA. Consequently, the optimized design is tested for robustness by a Monte Carlo analysis to find a solution that is both optimal and robust. System level simulations result in a signal-to-noise ratio (SNR) larger than 90 dB in a bandwidth of 64 Hz with a 200° s-1 angular rate input signal; the noise floor is about -100 dBV Hz-1/2. The simulations are compared to measured data from a hardware implementation. For zero input rotation with the gyroscope operating at atmospheric pressure, the spectrum of the output bitstream shows an obvious band-pass noise shaping and a deep notch at the gyroscope resonant frequency. The noise floor of measured power spectral density (PSD) of the output bitstream agrees well with simulation of the optimized system level model. The bias stability, rate sensitivity and nonlinearity of the gyroscope controlled by an optimized BP-ΣΔM closed-loop interface are 34.15° h-1, 22.3 mV °-1 s-1, 98 ppm, respectively. This compares to a simple open-loop interface for which the corresponding values are 89° h-1, 14.3 mV °-1 s-1, 7600 ppm, and a nonoptimized BP-ΣΔM closed-loop interface with corresponding values of 60° h-1, 17 mV °-1 s-1, 200 ppm.
High speed and wide bandwidth delta-sigma ADCs
Bolatkale, Muhammed; Makinwa, Kofi A A
2014-01-01
This book describes techniques for realizing wide bandwidth (125MHz) over-sampled analog-to-digital converters (ADCs) in nanometer-CMOS processes. The authors offer a clear and complete picture of system level challenges and practical design solutions in high-speed Delta-Sigma modulators. Readers will be enabled to implement ADCs as continuous-time delta-sigma (CT∆Σ) modulators, offering simple resistive inputs, which do not require the use of power-hungry input buffers, as well as offering inherent anti-aliasing, which simplifies system integration. The authors focus on the design of high speed and wide-bandwidth ΔΣMs that make a step in bandwidth range which was previously only possible with Nyquist converters. More specifically, this book describes the stability, power efficiency, and linearity limits of ΔΣMs, aiming at a GHz sampling frequency. • Provides overview of trends in Wide Bandwidth and High Dynamic Range analog-to-digital converters (ADCs); • Enables the design of a wide band...
Institute of Scientific and Technical Information of China (English)
2013-01-01
In order to make the analog - digital converter can be directly used for various battery capacity measurement system without voltage conversion chip ,the modulator in the Delta -Sigma ADC is designed in second-order single-loop structure with 0 .35μm CMOS technology ,and its measurement scope of application range 1 .4 V to 4 .2 V with 12bits resolution at the 5V power supply .The ADC with this modulator has the advantages of wide measurement scope of range to batteries and low cost .% 为使模拟－数字信号转换芯片能直接用于各种电池电量测量的系统中而无需另加电压转换芯片，在应用于Delta－Sigma结构的ADC（模数转换器）的调制器设计中，使用0．35μm CMOS的集成电路工艺，采用二阶单环的电路结构，在5V供电的工作电压下可达到的电压测量范围为1．4V至4．2V ，测量精度为12位．因而采用此Del-ta－Sigma调制器的ADC可直接用于多种电池种类的电量测量，且具有制作成本低廉的特点．
van Roermund, Arthur
2007-01-01
Preface. Part I: Structured Mixed-Mode Design. Introduction. Structured Oscillator Design; C. Verhoeven, A. van Staveren. Systematic Design of High-frequency gm-C Filters; E. Lauwers, G. Gielen. Structured LNA Design; E.H. Nordholt. High-Level Simulation and Modeling Tools for Mixed-Signal Front-ends of Wireless Systems; P. Wambacq, et al. Structured Simulation-Based Analog Design Synthesis; R.A. Rutenbar. Structured Analog layout Design; K. Lampaert. Part II: Multi-Bit Sigma Delta Converters. Introduction. Architecture Considerations for Multi-Bit SigmaDelta ADCs; T. Brooks. Multirate Sigma-Delta Modulators, an Alternative to Multibit; F. Colodro, A. Torralba. Circuit Design Aspects of Multi-Bit Delta-Sigma Converters; Y. Geerts, et al. High-speed Digital to Analog Converter Issues with Applications to Sigma Delta Modulators; K. Doris, et al. Correction-Free Multi-Bit Sigma-Delta Modulators for ADSL; R. del Rio, et al. Sigma Delta Converters in Wireline Communications; A. Wiesbauer, et al. Part III: Short Ra...
A sigma-delta-based sparse synthetic aperture beamformer for real-time 3-D ultrasound.
Inerfield, M; Lockwood, G R; Garverick, S L
2002-02-01
Sigma-delta modulation allows delay resolution in ultrasound beamformers to be achieved by simple clock cycle delays applied to the undecimated bit-stream, greatly reducing the complexity of the signal processing and the number of bits in the datapath. The simplifications offered by this technique have the potential for low power and portable operation in advanced systems such as 3-D and color Doppler imagers. In this paper, an architecture for a portable, real-time, 3-D sparse synthetic aperture ultrasound beamformer based on sigma-delta modulation is presented, and its simulated performance is analyzed. Specifically, with a 65-element linear phased array and three transmit events, this architecture is shown to achieve a 1.1 degrees beamwidth, a -54-dB secondary lobe level, and a theoretical frame rate of 1700 frames/s at lambda/64 delay resolution using a second-order low pass sigma-delta modulator. Finally, a technique for modifying the proposed multi-beam architecture to allow improved analog-to-digital (A/D) resolution by premodulating the input signal for bandpass sigma-delta modulation is also presented.
Novel Design for High Speed and Resolution Delta-sigma A/D Converter
Institute of Scientific and Technical Information of China (English)
TANG Sheng-xue; HE Yi-gang; GUO Jie-rong; LI Hong-min
2007-01-01
The delta-sigma converter is one of the high speed and resolution analog-to-digital modulators. Its implementation needs the low oversampling technique and the multi-bit D/A converter. The noise induced by the multi-bit D/A converter becomes one of the key factors deteriorating the signal-to-noise rate of the delta-sigma A/D converter. A novel structure with signal unity transfunction, dynamic element matching(DEM) and noise-shaping is discussed. The method is investigated to design converter based on the proposed structure. The behavior simulation indicates that the structure and the design method are feasible.
An 18-bit high performance audio {sigma}-{Delta} D/A converter
Energy Technology Data Exchange (ETDEWEB)
Zhang Hao; Han Yan; Han Xiaoxia; Wang Hao; Liang Guo [Institute of Microelectronics and Photoelectronics, Zhejiang University, Hangzhou 310027 (China); Huang Xiaowei [CISD, Institute of Microelectronic CAD, Hangzhou 310018 (China); Cheung, Ray C., E-mail: huangxw@hdu.edu.c [Department of Electronic Engineering, City University of Hong Kong (Hong Kong)
2010-07-15
A multi-bit quantized high performance sigma-delta ({sigma}-{Delta}) audio DAC is presented. Compared to its single-bit counterpart, the multi-bit quantization offers many advantages, such as simpler {sigma}-{Delta} modulator circuit, lower clock frequency and smaller spurious tones. With the data weighted average (DWA) mismatch shaping algorithm, element mismatch errors induced by multi-bit quantization can be pushed out of the signal band, hence the noise floor inside the signal band is greatly lowered. To cope with the crosstalk between digital and analog circuits, every analog component is surrounded by a guard ring, which is an innovative attempt. The 18-bit DAC with the above techniques, which is implemented in a 0.18 {mu}m mixed-signal CMOS process, occupies a core area of 1.86 mm{sup 2}. The measured dynamic range (DR) and peak SNDR are 96 dB and 88 dB, respectively.
CMOS sigma-delta converters practical design guide
De la Rosa, Jose M
2013-01-01
A comprehensive overview of Sigma-Delta Analog-to-Digital Converters (ADCs) and a practical guide to their design in nano-scale CMOS for optimal performance. This book presents a systematic and comprehensive compilation of sigma-delta converter operating principles, the new advances in architectures and circuits, design methodologies and practical considerations - going from system-level specifications to silicon integration, packaging and measurements, with emphasis on nanometer CMOS implementation. The book emphasizes practical design issues - from high-level behavioural modelling i
A dynamic focusing technique for delta-sigma-based beamformers.
Li, P C; Huang, J J; Liu, H L; O'Donnell, M
2000-10-01
Beamformation using oversampling delta-sigma (deltasigma) modulators has been proposed for diagnostic ultrasound. Such a beamformer can reduce the size, complexity and cost of an imaging system while providing adequate signal-to-quantization noise ratio (SQNR). High quality images can also be generated if dynamic receive delays are applied correctly. Several dynamic focusing techniques were previously proposed. Generally, an additional bit or extra compensation circuit is required to preserve the power and frequency distribution of the signal. Without preserving the power and frequency distribution, the image background noise is increased. In this paper, an alternative technique is presented. The new technique exploits the symmetry of focusing delays relative to the center of a transducer array. By properly synchronizing the delays and selecting the inserted values, no noise is added to the beam sum signal and the image background level is not increased. Using real ultrasound data, it is shown that the proposed technique provides the same imaging performance as the previous approaches with reduced system complexity by using only a single bit to encode the output of the deltasigma modulator.
High Speed and Wide Bandwidth Delta-Sigma ADCs
Bolatkale, M.
2013-01-01
This thesis describes the theory, design and implementation of a high-speed, high-performance continuous-time delta-sigma (CTΔΣ) ADC for applications such as medical imaging, high-definition video processing, and wireline and wireless communications. In order to achieve a GHz clocking speed, this
High Speed and Wide Bandwidth Delta-Sigma ADCs
Bolatkale, M.
2013-01-01
This thesis describes the theory, design and implementation of a high-speed, high-performance continuous-time delta-sigma (CTΔΣ) ADC for applications such as medical imaging, high-definition video processing, and wireline and wireless communications. In order to achieve a GHz clocking speed, this th
GaAs multibit delta-sigma A/D converters based upon a new comparator design
Energy Technology Data Exchange (ETDEWEB)
Hickling, R.M.; Yagi, M.N.; Salman, H.H. [TechnoConcepts, Inc., Newbury Park, CA (United States)
1995-12-31
In this paper, the design of multibit delta-sigma converters based upon a new comparator bank structure is described. The comparator bank approach (patent pending) eliminates the need for comparator threshold terminals, allowing each of the individual latched comparators to operate upon the same differential input signal. This new comparator design was incorporated into a complete four-bit delta-sigma modulator which was fabricated on a 0.6{mu}m GaAs MESFET process.
A Delta-Sigma Analog-to-Digital Converter Using Resonant Tunneling Diodes
Yokoyama, Yuji; Ohno, Yutaka; Kishimoto, Shigeru; Maezawa, Koichi; Mizutani, Takashi
2001-10-01
A novel delta-sigma (ΔΣ) analog-to-digital converter (ADC) using resonant tunneling diodes (RTDs) is proposed. A ΔΣ modulator circuit, which is the key element of the ΔΣ ADC, can be designed in a very simple form using a monostable-bistable transition logic element (MOBILE). The operation of this ΔΣ modulator circuit is confirmed by numerical simulation.
Design and Research on Sigma-Delta Digital-to-Analog Converters for Audio Power Amplifiers
Puidokas, Vytenis
2011-01-01
The dissertation investigates the issues of analyzing a digital Sigma-Delta digital-to-analog converter (DAC) for audio power amplifiers. The main objects of research include a digital Sigma-Delta audio power DAC, improvement of its structure and an experimental research. The primary purpose of the dissertation is to suggest methods for improvement the structure of digital Sigma-Delta audio power DAC interpolator and the converter analysis. Disertacijoje nagrinėjami Sigma-Delta skaitmenini...
VHDL Implementation of Sigma-Delta Analog To Digital Converter
Chavan, R. N.; Chougule, D. G.
2010-11-01
Sigma-Delta modulation techniques provide a range of opportunities in a signal processing system for both increasing performance and data path optimization along the silicon area axis in the design space. One of the most challenging tasks in Analog to Digital Converter (ADC) design is to adapt the circuitry to ever new CMOS process technology. For digital circuits the number of gates per square mm app. doubles per chip generation. Integration of analog parts in newer deep submicron technologies is much more tough and additionally complicated because the usable voltage ranges are decreasing with every new integration step. This paper shows an approach which only uses 2 resistors and 1 capacitor which are located outside a pure digital chip. So all integration advantages of pure digital chips are preserved, there is no design effort for a new chip generation and the ADC also can be used for FPGAs. Resolutions of up to 16 bit are achievable. Sample rates in the 1 MHz region are feasible so that the approach is also useful for ADCs for xDSL technologies.
A low-power triple-mode sigma-delta DAC for reconfigurable (WCDMA/TD-SCDMA/GSM) transmitters
Energy Technology Data Exchange (ETDEWEB)
Qiu Dong; Yi Ting; Hong Zhiliang, E-mail: yiting@fudan.edu.cn [State Key Laboratory of ASIC and System, Fudan University, Shanghai 201203 (China)
2011-02-15
A sigma-delta ({Sigma}{Delta}) DAC with channel filtering for multi-standard wireless transmitters used in the software-defined-radio (SDR) system is presented. The conversion frequency, transfer function of the digital filter and the {Sigma}{Delta} modulator, word-length of the IDAC and cut-off frequency of the analog reconstruction filter can be digitally programmed to satisfy specifications of WCDMA, TD-SCDMA and GSM standards. The {Sigma}{Delta} DAC fabricated in SMIC 0.13-{mu}m CMOS process occupies a die area of 0.72 mm{sup 2}, while consuming 5.52/4.82/3.04 mW in WCDMA/TD-SCDMA/GSM mode from a single 1.2-V supply voltage. The measured SFDR is 62.8/60.1/75.5 dB for WCDMA/TD-SCDMA/GSM mode, respectively. (semiconductor integrated circuits)
A Delta-Sigma beamformer with integrated apodization
DEFF Research Database (Denmark)
Tomov, Borislav Gueorguiev; Stuart, Matthias Bo; Hemmsen, Martin Christian
2013-01-01
remains the same as in an unmodified one. The outputs of all receiving channels are delayed and summed, and the resulting multi-bit sample stream is filtered and decimated to become an image line. The simplicity of this beamformer allows the production of high-channel-count or very compact beamformers......This paper presents a new design of a discrete time Delta-Sigma (ΔΣ) oversampled ultrasound beamformer which integrates individual channel apodization by means of variable feedback voltage in the Delta-Sigma analog to digital (A/D) converters. The output bit-width of each oversampled A/D converter...... suitable for 2-D arrays or compact portable scanners. The new design is evaluated using measured data from the research scanner SARUS and a BK-8811 192 element linear array transducer (BK Medical, Herlev, Denmark), insonifying a water-filled wire phantom containing four wires orthogonal to the image plane...
Digital Pixel Sensor Array with Logarithmic Delta-Sigma Architecture
Mahmoodi, Alireza; Li, Jing; Joseph, Dileepan
2013-01-01
Like the human eye, logarithmic image sensors achieve wide dynamic range easily at video rates, but, unlike the human eye, they suffer from low peak signal-to-noise-and-distortion ratios (PSNDRs). To improve the PSNDR, we propose integrating a delta-sigma analog-to-digital converter (ADC) in each pixel. An image sensor employing this architecture is designed, built and tested in 0.18 micron complementary metal-oxide-semiconductor (CMOS) technology. It achieves a PSNDR better than state-of-the-art logarithmic sensors and comparable to the human eye. As the approach concerns an array of many ADCs, we use a small-area low-power delta-sigma design. For scalability, each pixel has its own decimator. The prototype is compared to a variety of other image sensors, linear and nonlinear, from industry and academia. PMID:23959239
Digital Pixel Sensor Array with Logarithmic Delta-Sigma Architecture
Directory of Open Access Journals (Sweden)
Jing Li
2013-08-01
Full Text Available Like the human eye, logarithmic image sensors achieve wide dynamic range easily at video rates, but, unlike the human eye, they suffer from low peak signal-to-noise-and-distortion ratios (PSNDRs. To improve the PSNDR, we propose integrating a delta-sigma analog-to-digital converter (ADC in each pixel. An image sensor employing this architecture is designed, built and tested in 0.18 micron complementary metal-oxide-semiconductor (CMOS technology. It achieves a PSNDR better than state-of-the-art logarithmic sensors and comparable to the human eye. As the approach concerns an array of many ADCs, we use a small-area low-power delta-sigma design. For scalability, each pixel has its own decimator. The prototype is compared to a variety of other image sensors, linear and nonlinear, from industry and academia.
Digital pixel sensor array with logarithmic delta-sigma architecture.
Mahmoodi, Alireza; Li, Jing; Joseph, Dileepan
2013-08-16
Like the human eye, logarithmic image sensors achieve wide dynamic range easily at video rates, but, unlike the human eye, they suffer from low peak signal-to-noise-and-distortion ratios (PSNDRs). To improve the PSNDR, we propose integrating a delta-sigma analog-to-digital converter (ADC) in each pixel. An image sensor employing this architecture is designed, built and tested in 0.18 micron complementary metal-oxide-semiconductor (CMOS) technology. It achieves a PSNDR better than state-of-the-art logarithmic sensors and comparable to the human eye. As the approach concerns an array of many ADCs, we use a small-area low-power delta-sigma design. For scalability, each pixel has its own decimator. The prototype is compared to a variety of other image sensors, linear and nonlinear, from industry and academia.
All digital monolithic scanning readout based on Sigma-Delta analog to digital conversion
Mandl, William; Rutschow, Carl
1992-07-01
It is generally accepted that sensor systems can benefit from some form of on-focal-plane A/D conversion in terms of overall system noise improvement. The issue of whether or not the Delta-Sigma modulation process can be applied to the development of an approach using conventional A/D converters or cryogenic circuit materials is addressed from the standpoint of the scanning focal plane. Each pixel row of the scanning sensor is treated as a continuous analog signal source with a fixed signal bandwidth. By allocating a Delta-Sigma converter per sensor pixel row, theory predicts the oversample rate required to achieve the designed conversion resolution. The Delta-Sigma consists of two major parts. The modulator, which samples the analog input and develops a corresponding digital bit stream, and the digital signal processor, which compresses the bit stream into the Nyquist rate multibit codes and performs noise filtering, are described. Only the modulator needs to be on the focal plane since its output is digital. This reduces the development problem to one of fitting the modulator only into the allocated space and power budget per sensor.
Multiple-Description Coding by Dithered Delta-Sigma Quantization
Ostergaard, Jan
2007-01-01
We address the connection between the multiple-description (MD) problem and Delta-Sigma quantization. The inherent redundancy due to oversampling in Delta-Sigma quantization, and the simple linear-additive noise model resulting from dithered lattice quantization, allow us to construct a symmetric MD coding scheme. We show that the use of a noise shaping filter makes it possible to trade off central distortion for side distortion. Asymptotically as the dimension of the lattice vector quantizer and order of the noise shaping filter approach infinity, the entropy rate of the dithered Delta-Sigma quantization scheme approaches the symmetric two-channel MD rate-distortion function for a memoryless Gaussian source and MSE fidelity criterion, at any side-to-central distortion ratio and any resolution. In the optimal scheme, the infinite-order noise shaping filter must be minimum phase and have a piece-wise flat power spectrum with a single jump discontinuity. We further show that the optimal noise-shaping filter of ...
12位Sigma-Delta模数转换器的降采样滤波器设计%Decimation Filter Design for 12-bit Sigma-Delta ADC
Institute of Scientific and Technical Information of China (English)
黄博志
2014-01-01
The paper presents a signal-noise-ratio (SNR) based design method for the decimation filter of a 12-bit Sigma-Delta ADC (analog-to-digital converter). Sigma-Delta ADC consists of Sigma-Delta modulatorand decimation filter. Sigma-Delta modulatoris used for signal modulation and over-sampling quantization. Decimation filter is used for down-sampling the digital signal to its normal frequency and the quantization noise is filtered at the same time. Sigma-Delta ADC has higher sampling frequency, higher precision and less hardware cost than traditional ADC. There are two specifications for decimation filter:down-sampling rate and filter performance. This filter design method is driven by SNR and two solutions are applied. Simulation is done using MATLAB and the result is met the requirement of 12-bit Sigma-Delta ADC with SNR larger than 74 dB.%一种由SNR（信噪比）驱动的滤波器设计，用于12位Sigma-Delta模数转换器。Sigma-Delta模数转换器包括Sigma-Delta调制器和降采样滤波器两部分，首先用Sigma-Delta调制器对信号进行过采样率量化，然后通过降采样滤波器进行数字信号处理，将信号还原到原始采样率并去除量化噪声。和传统的模数转换器相比，Sigma-Delta模数转换器具有采样率高、精度高、面积小等优点。Sigma-Delta模数转换器的滤波器设计有降采样率和滤波性能两个指标要求，该设计方法由SNR驱动并采用了两种滤波器方案，设计结果在MATLAB里进行了仿真，其SNR大于74 dB，达到12位Sigma-Delta模数转换器的要求。
A 16-bit cascaded sigma-delta pipeline A/D converter
Institute of Scientific and Technical Information of China (English)
Li Liang; Li Ruzhang; Yu Zhou; Zhang Jiabin; Zhang Jun'an
2009-01-01
A low-noise cascaded multi-bit sigma-delta pipeline analog-to-digital converter (ADC) with a low oversampling rate is presented. The architecture is composed of a 2-order 5-bit sigma-delta modulator and a cascaded 4-stage 12-bit pipelined ADC, and operates at a low 8X oversampling rate, The static and dynamic performances of the whole ADC can be improved by using dynamic element matching technique. The ADC operates at a 4 MHz clock rate and dissipates 300 mW at a 5 V/3 V analog/digital power supply. It is developed in a 0.35 μm CMOS process and achieves an SNR of 82 dB.
A Design of Sigma-Delta ADC Using OTA
Directory of Open Access Journals (Sweden)
Miss. Niveditha Yadav M
2017-06-01
Full Text Available Sigma-Delta Analog-to-Digital converter (ADC, is widely used in portable electronic products. An operational transconductance amplifier (OTA is one of the most important components of ADC. This paper presents a new design of two stages OTA. The design incorporates Sleep insertion technique and leakage feedback current approach for improving design parameters such as gain, and power as compared to earlier work. The design is simulated in 0.18µm CMOS technology with supply voltage 1.8V.
Practical Design of Delta-Sigma Multiple Description Audio Coding
DEFF Research Database (Denmark)
Leegaard, Jack Højholt; Østergaard, Jan; Jensen, Søren Holdt
2014-01-01
It was recently shown that delta-sigma quantization (DSQ) can be used for optimal multiple description (MD) coding of Gaussian sources. The DSQ scheme combined oversampling, prediction, and noise-shaping in order to trade off side distortion for central distortion in MD coding. It was shown......, it is possible to obtain good quality audio in the presence of packet losses. Simulations on real audio reveal that, contrary to existing designs, it is straightforward to obtain a large number of trade-off points between side distortion and central distortion, which makes the proposed coder suitable for a wide...
Institute of Scientific and Technical Information of China (English)
陶呈瑶; 邓康发
2013-01-01
针对微加速度计接口电路的Sigma-Delta(撞驻)数字反馈系统，提出了一种基于脉宽调制( PWM)的力反馈回路：利用模拟低通滤波器将PWM波解调成模拟输出信号，具有滤波和数模转换功能。首先建立微加速度计撞驻闭环反馈系统的Simulink模型并进行了系统级仿真。之后采用Filter Solutions滤波器设计软件确定三阶低通巴特沃斯滤波器，并采用Pspice仿真软件进行电路级仿真。最后将制作的PCB版电路进行测试：PWM波通过力反馈回路能还原成高保真度的模拟信号，输出信号和输入信号的频率相对误差小于0.36%，等效DAC分辨率为8 bit。试验表明，此方案结构简单、成本低，能以较低电路复杂度实现高精度的模拟信号输出。%Aiming at the Sigma-Delta(Σ△) digital force feedback system in Mcro-accelerometer interface circuit,this paper presents a force feedback loop based on Pulse Width Modulator(PWM). The PWM wave can be translated into output analog singal using low pass filter,indicating that this circuit has a dual function of filter and digital to analog conversion( DAC) . Firstly,Σ△closed loop feedback system was simulated in Simulink model for system level simulation,then Filter Solutions software was used for designing three-order Butterworth low pass filter,and Pspice software was adopted for circuit level simulation. Finally electronic circuit was made by PCB and then tested. Through the force back loop,the wave can be successfully translate to undistorted analog signal,and the maximun relative error is below 0. 36% compared to the input signal,the equivalent DAC resolution is 8 bit. This experiment shows that this method has the advantages of simple structure,low cost,and easy way to produce high precise output analog signal.
Study of First-Order Thermal Sigma-Delta Architecture for Convective Accelerometers
Nouet, Pascal; Latorre, Laurent; Nouet, Pascal
2008-01-01
This paper presents the study of an original closed-loop conditioning approach for fully-integrated convective inertial sensors. The method is applied to an accelerometer manufactured on a standard CMOS technology using an auto-aligned bulk etching step. Using the thermal behavior of the sensor as a summing function, a first order sigma-delta modulator is built. This "electro-physical" modulator realizes an analog-to-digital conversion of the signal. Besides the feedback scheme should improve the sensor performance.
Development of superconducting bandpass delta-sigma analog-to-digital converter
Energy Technology Data Exchange (ETDEWEB)
Bulzacchelli, John F.; Lee, Hae-Seung; Misewich, James A.; Ketchen, Mark
2004-10-01
This paper recounts the development of a superconducting bandpass delta-sigma ({delta}{sigma}) modulator for direct analog-to-digital conversion of radio frequency signals in the GHz range. The modulator design benefits from several advantages of superconducting electronics: high-Q resonators, fast Josephson comparators, naturally quantized single flux quantum pulses, and high circuit sensitivity. The measured center frequency (2.23 GHz), sampling rate (up to 45 GHz), dynamic range (greater than 57 dB over a 19.6 MHz bandwidth), and input sensitivity (-17.4 dBm full-scale) of the bandpass modulator are the highest reported to date in any technology. The SNR (49 dB over a 20.8 MHz bandwidth) is limited by the frequency resolution of the measurement but still exceeds the SNRs of semiconductor modulators with comparable center frequencies. The design of the modulator test chip and the high speed testing methodology are reviewed. Finally, the paper examines the prospects for improved performance with more advanced modulator architectures.
Maezawa, Koichi; Sakou, Mario; Matsubara, Wataru; Mizutani, Takashi; Matsuzaki, Hideaki
2006-04-01
A ΔΣ modulator using a frequency modulation intermediate signal was demonstrated using a resonant tunneling logic gate called a monostable bistable transition logic element (MOBILE). This ΔΣ modulator is based on the nature of an FM signal and suitable for high-speed operation. Experiments using an InP-based MOBILE demonstrate good noise shaping characteristics. Moreover, the operation with a higher FM carrier frequency than the sampling frequency was demonstrated, showing equally good noise shaping performance. This makes the design of the voltage-controlled oscillator, which is a key component of the FM ΔΣ modulator, much easier. Consequently, an FM ΔΣ modulator using MOBILE is promising for high-resolution, wide-band analog-to-digital converters (ADCs).
A 1-V 60-μW 85-dB dynamic range continuous-time third-order sigma-delta modulator
Institute of Scientific and Technical Information of China (English)
Li Yuanwen; Qi Da; Dong Yifeng; Xu Jun; Ren Junyan
2009-01-01
A 1-V third order one-bit continuous-time (CT) ΣΔ modulator is presented. Designed in the SMIC mixed-signal 0.13-μm CMOS process, the modulator utilizes active RC integrators to implement the loop filter. An efficient circuit design methodology for the CT ΣΔ modulator is proposed and verified. Low power dissipation is achieved through the use of two-stage class A/AB amplifiers. The presented modulator achieves 81.4-dB SNDR and 85-dBdynamic range in a 20-kHz bandwidth with an over sampling ratio of 128. The total power consumption of the modulator is only 60μW from a 1-V power supply and the prototype occupies an active area of 0.12 mm~2.
Design of a High-speed Wide-band Continuous-Time Delta-Sigma Modulator%一种高速宽带连续时间 Delta-Sigma调制器设计
Institute of Scientific and Technical Information of China (English)
王轶彬; 韩晨曦; 李冬梅
2014-01-01
利用MATLAB SIMULINK工具设计了一款高速连续时间Delta‐Sigma调制器．该调制器采用单环3阶4位量化带前馈结构，设计指标为14位精度、2M Hz信号带宽．通过对积分器运放有限直流增益（DC gain）、积分器运放有限增益带宽积（GBW）、额外环路延时（ELD ）等电路非理想因素进行建模，确定各非理想因素边界范围并提供电路级各模块设计指标．在U M C 180 nm工艺下进行电路、版图设计及流片实现．量化器中设计采用了一款高速、高精度、低噪声、带预放大级的动态锁存比较器．调制器中采用一种低延时的动态元件匹配（DEM ）结构来抑制DAC单元非线性失配对系统性能造成的影响．通过电阻RPI引入一条前馈路径来对额外环路延时（ELD ）进行补偿．电路级前仿真达到13．5 bit有效位数（ENOB），核心面积约0．1 mm2，优值（FOM ）约为220 fJ ．%This paper presents a high‐speed wide‐band continuous‐time (CT ) Delta‐Sigma (Δ‐Σ) modulator .The modulator is modeled in MATLAB SIMULINK with a single‐loop 3rd‐order 4‐bit quantization structure . By modeling non‐ideal factors such as limited OPAMP DC gain ,limited gain bandwidth product (GBW) and excess loop delay (ELD) ,design properties of circuit module are determined .The modulator is designed and implemented in UMC 180 nm process . High‐speed dynamic latch comparator with low‐noise and high‐resolution is designed for quantization .Dynamic element matching (DEM ) module with low latency is included to suppress DAC mismatching .A direct feedforward path is introduced by RPI to compensate for excess loop delay (ELD) .The modulator achieves a pre‐layout 83 dB signal to noise distortion ratio (SNDR) with a figure of merit (FOM ) of 220 fJ/conv‐step and occupies 0 .1 mm2 active area .
Waki, Naoya; Sato, Hiroki; Hyogo, Akira; Sekine, Keitaro
In this paper, horizontal (where an opamp is shared in two adjacent stages) and vertical (where an opamp is shared across two paths) opamp sharing techniques for a two-path band-pass (BP) ΔΣ modulator are described, and input-feedforward two-path fourth-order BP ΔΣ modulators that have only two opamps are proposed. The proposed modulators are based on the horizontal or vertical opamp sharing technique. They can be realized with both a summation circuit using a switched capacitor (SC) network and a second-order high-pass filter (HPF) with a horizontal shared opamp or a double-sampling first-order HPF with a vertical shared opamp, which are based on an SC first-order HPF with an opamp. These techniques can reduce the number of opamps with no additional component and the chip area as well as realize lower power consumption.
A 16-bit sigma-delta ADC applied in micro-machined inertial sensor
Directory of Open Access Journals (Sweden)
Li Qiang
2015-04-01
Full Text Available This paper presents a low-distortion sigma-delta (Σ-Δ ADC for micro-machined inertial sensors. The design adopts a single-loop, fourth-order low-pass single-bit modulator with feedforward paths which can ensure the signal transfer lossless and reduce the nonlinearity and power consumption. The chip is manufactured in standard 0.5µm CMOS process, and the area is 2.2mm2. The ADC achieves 108dB signal to noise ratio (SNR and 110dB dynamic range (DR. Total power consumption is less than 15mW with 5V supply.
High-speed decimation filter for a delta-sigma analog-to-digital converter
Xie, Yiqun
1998-10-01
A decimation filter is a key component in a delta-sigma analog-to-digital converter system. The importance of the design of the decimation filter for the delta-sigma converter is due to several factors. The first, high resolution, which is the major advantage of the delta-sigma converter, can only be possible if the decimation filter can remove the high-frequency noise generated by the quantizer, without introducing significant distortion of the signals. The second is that a decimation filter occupies the dominant portion of the area and consumes the dominant portion of power in a delta-sigma converter; therefore, a well designed decimation filter can significantly save power and area for the converter and reduce production cost. The third is that the first-stage decimation filter has to operate in a very high frequency, equal to the sampling frequency of the delta-sigma converter. The circuit complexity and high-speed operation pose challenges to the design of a decimation filter. A superconductive decimation filter has the advantage of allowing sampling the analog signal at an ultra-high frequency in the modulator. This dissertation presents a superconductive decimation filter designed with voltage-state logic, which has the advantage of robustness, being relatively insensitive to clock timing, and easier to interface with semiconductor circuitry than other prevailing superconductive logic families. A structure of a multi-channel-input filter is developed to improve the speed performance. The filter is aimed to work at 16 Gbit/s or higher with state-of-the-art niobium technology. Extensive simulation is performed to optimize the circuit design. Circuit yield is predicted by Monte Carlo simulation using the knowledge of existing process variations. To improve yield, the circuit is simplified by using an accumulate-and-dump structure. A novel XOR gate is invented and used in the circuit to reduce gate count even further. A single-rail operation of signals, rather
Circuits and systems based on delta modulation linear, nonlinear and mixed mode processing
Zrilic, Djuro G
2005-01-01
This book is intended for students and professionals who are interested in the field of digital signal processing of delta-sigma modulated sequences. The overall focus is on the development of algorithms and circuits for linear, non-linear, and mixed mode processing of delta-sigma modulated pulse streams. The material presented here is directly relevant to applications in digital communication, DSP, instrumentation, and control.
Design of Continuous Time Multibit Sigma Delta ADC for Next Generation Wireless Applications
Directory of Open Access Journals (Sweden)
Sharon Theresa George
2015-03-01
Full Text Available This paper presents the design of CT ΣΔ modulator which can provide high DR and SNR over a 20 MHz signal bandwidth. So far all the CT SDM uses either feedback or feedforward loop filter architecture. The proposed topology is a 3rd order low-pass sigma-delta modulator, which employs a combination of feedforward and feedback schemes. Loop filter is designed as RC integrators due to its high linearity and easy interface. The design starts from system level using Matlab/Simulink. Then, the first integrator in the loop, which is the most critical block in the modulator, is implemented at transistor level using Cadence Virtuoso 180 nm CMOS technology.
A high-performance, low-power {sigma} {Delta} ADC for digital audio applications
Energy Technology Data Exchange (ETDEWEB)
Luo Hao; Han Yan; Han Xiaoxia; Ma Shaoyu; Ying Peng; Zhu Dazhong [Institute of Microelectronics and Photoelectronics, Zhejiang University, Hangzhou 310027 (China); Cheung, Ray C. C., E-mail: hany@zju.edu.c [Department of Electronic Engineering, City University of Hong Kong, Hong Kong 999077 (China)
2010-05-15
A high-performance low-power {sigma} {Delta} analog-to-digital converter (ADC) for digital audio applications is described. It consists of a 2-1 cascaded {sigma} {Delta} modulator and a decimation filter. Various design optimizations are implemented in the system design, circuit implementation and layout design, including a high-overload-level coefficient-optimized modulator architecture, a power-efficient class A/AB operational transconductance amplifier, as well as a multi-stage decimation filter conserving area and power consumption. The ADC is implemented in the SMIC 0.18-{mu}m CMOS mixed-signal process. The experimental chip achieves a peak signal-to-noise-plus-distortion ratio of 90 dB and a dynamic range of 94 dB over 22.05-kHz audio band and occupies 2.1 mm{sup 2}, which dissipates only 2.1 mA quiescent current in the analog circuits. (semiconductor integrated circuits)
Delta isobars in relativistic mean-field models with $\\sigma$-scaled hadron masses and couplings
Kolomeitsev, E E; Voskresensky, D N
2016-01-01
We extend the relativistic mean-field models with hadron masses and meson-baryon coupling constants dependent on the scalar $\\sigma$ field, studied previously to incorporate $\\Delta(1232)$ baryons. Available empirical information is analyzed to put constraints on the couplings of $\\Delta$s with meson fields. Conditions for the appearance of $\\Delta$s are studied. We demonstrate that with inclusion of the $\\Delta$s our equations of state continue to fulfill majority of known empirical constraints including the pressure-density constraint from heavy-ion collisions, the constraint on the maximum mass of the neutron stars, the direct Urca and the gravitational-baryon mass ratio constraints.
Directory of Open Access Journals (Sweden)
Lesyani León Viltre
2011-02-01
Full Text Available Se realiza un estudio sobre la conversión sigma-delta aplicada al control de inversores de enlace decontinua resonantes. Este tipo de configuración inversora (inversor resonante con enlace CD es factiblede utilizar como parte integrante de un sistema fotovoltaico de energía porque presenta la ventaja de quetodos los elementos conmutan a tensión o corriente cero, tanto los elementos de alta frecuencia como losque actúan de inversor, sin necesidad de modular la tensión de continua, lo cual simplifica considerablementeel lazo de control. La conversión análoga digital es una etapa clave en la mayoría de los sistemaselectrónicos modernos. Una vez, en formato digital, las señales pueden ser fácilmente almacenadas yprocesadas para obtener la información deseada. This paper presents an analysis of the sigma-delta conversion applied to the control of the DC linkresonant inverters. This inverter configuration is often employed as a part of photovoltaic system becauseit presents the advantage that the semiconductors elements commute at zero tension or zero current. Ithappen on the high frequency elements and the inverter elements, and it is not necessary to modulate theDC tension, condition that simplified the control loop. Conversion analog-digital is an important step of thealmost every modern electronics systems. After the signal is translated to the digital format, it can beprocessed easily in order to obtain the required information.
Di, Li; Yintang, Yang; Zhangming, Zhu; Lichun, Shi; Xiaofeng, Wu; Jiangan, Wang
2010-02-01
An improved low distortion sigma-delta ADC (analog-to-digital converter) for wireless local area network standards is presented. A feed-forward MASH 2-2 multi-bit cascaded sigma-delta ADC is adopted; however, this work shows a much better performance than the ADCs which have been presented to date by adding a feedback factor in the second stage to improve the performance of the in-band SNDR (signal to noise and distortion ratio), using 4-bit ADCs in both stages to minimize the quantization noise. Data weighted averaging technology is therefore used to decrease the mismatch noise induced by the 4-bit DACs, which improves the SFDR (spurious free dynamic range) of the ADC. The modulator has been implemented by a 0.18 μm CMOS process and operates at a single 1.8 V supply voltage. Experimental results show that for a 1.25 MHz @ -6 dBFS input signal at 160 MHz sampling frequency, the improved ADC with all non-idealities considered achieves a peak SNDR of 80.9 dB and an SFDR of 87 dB, and the effective number of bits is 13.15 bits.
High-resolution IF-to-baseband sigma delta ADC for car radios
Silva, Paulo G R
2008-01-01
High-Resolution IF-to-Baseband SigmaDelta ADC for Car Radios addresses the theory, system level design and circuit implementation of a high-resolution continuous-time IF-to-baseband quadrature SigmaDelta ADC. The target application of this ADC is in AM/FM/IBOC car radios. The ADC achieves a dynamic range of 118dB, which eliminates the need for an IF VGA or AM channel filter in car radios.
An Integrated Multilevel Converter with Sigma Delta Control for LED Lighting
Gerber, Daniel L.
High brightness LEDs have become a mainstream lighting technology due to their efficiency, life span, and environmental benefits. As such, the lighting industry values LED drivers with low cost, small form factor, and long life span. Additional specifications that define a high quality LED driver are high efficiency, high power factor, wide-range dimming, minimal flicker, and a galvanically isolated output. The flyback LED driver is a popular topology that satisfies all these specifications, but it requires a bulky and costly flyback transformer. In addition, its passive methods for cancelling AC power ripple require electrolytic capacitors, which have been known to have life span issues. This dissertation details the design, construction, and verification of a novel LED driver that satisfies all the specifications. In addition, it does not require a flyback transformer or electrolytic capacitors, thus marking an improvement over the flyback driver on size, cost, and life span. This dissertation presents an integrated circuit (IC) LED driver, which features a pair of generalized multilevel converters that are controlled via sigma-delta modulation. The first is a multilevel rectifier responsible for power factor correction (PFC) and dimming. The PFC rectifier employs a second order sigma-delta loop to precisely control the input current harmonics and amplitude. The second is a bidirectional multilevel inverter used to cancel AC power ripple from the DC bus. This ripple-cancellation module transfers energy to and from a storage capacitor. It uses a first order sigma-delta loop with a preprogrammed waveform to swing the storage capacitor voltage. The system also contains an output stage that powers the LEDs with DC and provides for galvanic isolation. The output stage consists of an H-bridge stack that connects to the output through a small toroid transformer. The IC LED driver was simulated and prototyped on an ABCD silicon test chip. Testing and verification
Development of superconducting bandpass delta-sigma analog-to-digital converter
Bulzacchelli, John F.; Lee, Hae-Seung; Misewich, James A.; Ketchen, Mark B.
2004-10-01
This paper recounts the development of a superconducting bandpass delta-sigma (ΔΣ) modulator for direct analog-to-digital conversion of radio frequency signals in the GHz range. The modulator design benefits from several advantages of superconducting electronics: high-Q resonators, fast Josephson comparators, naturally quantized single flux quantum pulses, and high circuit sensitivity. The measured center frequency (2.23 GHz), sampling rate (up to 45 GHz), dynamic range (greater than 57 dB over a 19.6 MHz bandwidth), and input sensitivity (-17.4 dBm full-scale) of the bandpass modulator are the highest reported to date in any technology. The SNR (49 dB over a 20.8 MHz bandwidth) is limited by the frequency resolution of the measurement but still exceeds the SNRs of semiconductor modulators with comparable center frequencies. The design of the modulator test chip and the high speed testing methodology are reviewed. Finally, the paper examines the prospects for improved performance with more advanced modulator architectures.
光学Sigma-Delta模数转换器的研究进展%Research and development of optical sigma-delta analog to digital converter
Institute of Scientific and Technical Information of China (English)
周雯; 王目光; 李博
2012-01-01
Optical analog to digital conversion techniques have been the developing trend of analog to digital converter(ADC) with high conversion rate and high bit accuracy in recent years. As a kind of optical ADC, optical Sigma-Delta ADC has distinguished advantages such as high conversion accuracy and simple analog circuitry. Basic principle of optical Sigma-Delta ADC is introduced. The structures of several typical optical Sigma-Delta ADCs are described detailedly.Finally the merits and demerits of optical Sigma-Delta ADCs with different structures are summed up.%采用光学模数转换技术已经成为高转换速率、高比特精度模数转换器(ADC)的发展趋势.光学Sigma-Delta ADC作为一种光学ADC,具有转换精度高和模拟电路简单等显著优点.介绍了光学Sigma-Delta ADC的基本原理,详细阐述了几种典型的光学Sigma-Delta ADC的系统结构,对不同结构的光学Sigma-Delta ADC的优缺点进行了归纳总结.
High-Speed Superconductive Decimation Filter for Sigma-Delta Analog to Digital Converter
Wakamatsu, Tomu; Yamanashi, Yuki; Yoshikawa, Nobuyuki
2017-07-01
A superconducting decimation filter is required to convert high-speed output data from a superconducting sigma-delta analog to digital (A/D) modulator to low-speed data for data acquisition by room-temperature electronics. Because the operating frequency of the conventional superconducting decimation filter is lower than that of the maximum operation frequency of A/D modulator, the system performance of the superconducting A/D converter is limited by the decimation filter. We propose a decimation filter that can operate at the sampling frequency of the A/D modulator by hybridizing a shift-register-based and a counter-based decimation filters. The investigated decimation filter can be implemented with a practical circuit area. We designed and tested the investigated decimation filter. The simulation result indicates that the maximum operation frequency of the designed decimation filter is 39.8 GHz assuming the 2.5 kA/cm2 Nb fabrication process. We experimentally confirmed the low-speed operation of the designed decimation filter with the bias margin of 93.8%-110.8%.
A High Performance Sigma-Delta ADC for Audio Decoder Chip
Directory of Open Access Journals (Sweden)
Yu Fan
2013-11-01
Full Text Available This paper gives a high performance sigma delta Analog to Digital Converter (ADC applied in computer audio decoder chip. In this design, a 3rd-order single-loop CIFF topology is chosen to achieve the high performance ADC. Its signal bandwidth is 20KHz, sampling frequency is 10.24MHz and oversampling ratio is 256. Local feedback coefficient is used to reduce quantization noise. The non-linear model of modulator is given and the stability is analyzed. It is got that when quantizer gain is bigger than 0.322 the system is stable. According to simulation, Signal to Noise Ratio (SNR is 123.1dB and Effective Number of Bits (ENOB is 20.15bits. When input level is bigger than -3dBFs, the modulator is overload and becomes unstable. Then the integrator, quantizer and feed forward summation in ADC circuit are designed. Then the ADC is implemented in 0.6um CMOS process, and the test result shows that its performance is 99.28dB.
Low-consumption sigma-delta DAC for audio mobile applications
Benabes, Philippe; Kielbasa, Richard
2008-01-01
International audience; In this paper, we present a new Three-level D-to-A sigma delta converter for low consumption applications. The two one bit outputs of this converter can drive a loudspeaker directly without requiring passive components and with a sufficient audio quality. The global consumption is minimized by reducing the number of active states.
Developmental studies on the Sigma and Delta-1 glutathione transferases of Lucilia cuprina.
Pal, Ramavati; Sanil, Nitasha; Clark, Alan
2012-03-01
The glutathione transferases (GSTs) are a large group of enzymes having both detoxication roles and specialist metabolic functions. The present work represents an initial approach to identifying some of these roles by examining the variation of specific members of the family under differing conditions. The GSTs from Lucilia cuprina have been partially purified, members of two families being isolated, by the use of glutathione immobilised on epichlorhydrin-activated Sepharose 6B. The GSTs were separated by 2D SDS-PAGE and characterised by MALDI-TOF analysis of tryptic peptides. The mass fragments were then matched against the corresponding Drosophila melanogaster and Musca domestica sequences. GSTs were identified as coming from only the Sigma and Delta classes. The multiple Delta zones appear all to be derived from the Lucilia GSTD1 isoform. The distribution of these GST proteins has been studied during different developmental stages of the insect. Delta isoforms were present in all developmental stages of L. cuprina. The Sigma GST was not detectable in the egg, was just detectable in the larval and pupal stages and was the major GST isolated in the adult. Sigma and Delta isoforms were both found in all body segments of the insect. Both isoforms appear to undergo extensive post-translational modification. Activities of the two types of protein with model substrates have been determined.
Functional modules of sigma factor regulons guarantee adaptability and evolvability
Binder, Sebastian C.; Eckweiler, Denitsa; Schulz, Sebastian; Bielecka, Agata; Nicolai, Tanja; Franke, Raimo; Häussler, Susanne; Meyer-Hermann, Michael
2016-02-01
The focus of modern molecular biology turns from assigning functions to individual genes towards understanding the expression and regulation of complex sets of molecules. Here, we provide evidence that alternative sigma factor regulons in the pathogen Pseudomonas aeruginosa largely represent insulated functional modules which provide a critical level of biological organization involved in general adaptation and survival processes. Analysis of the operational state of the sigma factor network revealed that transcription factors functionally couple the sigma factor regulons and significantly modulate the transcription levels in the face of challenging environments. The threshold quality of newly evolved transcription factors was reached faster and more robustly in in silico testing when the structural organization of sigma factor networks was taken into account. These results indicate that the modular structures of alternative sigma factor regulons provide P. aeruginosa with a robust framework to function adequately in its environment and at the same time facilitate evolutionary change. Our data support the view that widespread modularity guarantees robustness of biological networks and is a key driver of evolvability.
Projeto e implementação de um transdutor sigma-delta térmico linear
Rosa, Valter da Conceição
2009-01-01
Neste trabalho é mostrado um transdutor sigma-delta térmico, i.e., um circuito realimentado baseado no modulador sigma-delta térmico. O circuito tem como base um modulador sigma-delta de primeira ordem de um bit, no qual algumas partes da conversão são realizadas por um termistor, po-dendo ser usado para realizar medidas digitais das grandezas que interagem com o sensor como: temperatura, radiação térmica e velocidade de fluido. Baseado neste princípio é demonstrado, através de uma aplicação ...
ROIC with on-chip sigma-delta AD converter for HgCdTe e-APD FPA
Chen, Guoqiang; Zhang, Junling; Wang, Pan; Zhou, Jie; Gao, Lei; Ding, Ruijun
2013-10-01
HgCdTe electron injection avalanche photodiodes (e-APDs) work at linear mode. A weak optical current signal is amplified orders of magnitude due to the internal avalanche mechanism and it has been demonstrated to be one of the most promising methods to focal-plane arrays (FPAs) for low-flux like hyper-spectral imaging and high-speed applications such as active imaging. This paper presents the design of a column-shared ADC for cooled e-APDs FPA. Designing a digital FPA requires fulfilling very stringent requirements in terms of power consumption, silicon area and speed. Among the various ADC architectures sigma-delta conversion is a promising solution for high-performance and medium size FPA such as 128×128. The performance of Sigma-delta ADC rather relies on the modulator structure which set over-sampling and noise shaping characteristics than on critical analog circuits. This makes them quite robust and flexible. A multistage noise shaping (MASH) 2-1 single bit architecture sigma-delta conversion with switched-capacitor circuits is designed for column-shared ADC, which is implanted in the GLOBALFOUNDRIES 0.35um CMOS process with 4-poly and 4-metal on the basis of a 100um pixel pitch. It operates under 3.3V supply and the output range of the quantizer is 2V. A quantization noise subtraction circuit in modulator is designed to subtract the quantization noise of first-stage modulator. The quantization noise of the modulator is shaped by a high-pass filter. The silicon area and power consumption are mainly determined by the decimation low pass filter. A cascaded integrator-comb (CIC) filter is designed as the digital decimator filter. CIC filter requires no multipliers and use limited storage thereby leading to more economical hardware implementation. The register word length of the filter in each stage is carefully dimensioned in order to minimize the required hardware. Furthermore, the digital filters operate with a reduced supply voltage to 1.5V. Simulation
Directory of Open Access Journals (Sweden)
M. Becker
2005-01-01
Full Text Available Dieser Beitrag stellt die Implementierung eines neuartigen Ansatzes einer effizienten Dezimator-Architektur für kaskadierte Sigma-Delta Modulatoren vor. Die Rekombinationslogik kaskadierter Modulatoren und die Korrektur des Verstärkungsfehlers zeitkontinuierlicher (CT Modulatoren werden in die erste Stufe des Dezimators integriert. Eine entsprechende Filtertopologie wird hergeleitet und auf einem Hardware-Emulator der Firma Mentor Graphics implementiert. Der Vergleich der vorgeschlagenen Struktur mit einer herkömmlichen Implementierung zeigt eine nennenswerte Verbesserung der Effizienz.
A continuous-time/discrete-time mixed audio-band sigma delta ADC
Institute of Scientific and Technical Information of China (English)
Liu Yan; Hua Siliang; Wang Donghui; Hou Chaohuan
2011-01-01
This paper introduces a mixed continuous-time/discrete-time, single-loop, fourth-order, 4-bit audioband sigma delta ADC that combines the benefits of continuous-time and discrete-time circuits, while mitigating the challenges associated with continuous-time design. Measurement results show that the peak SNR of this ADC reaches 100 dB and the total power consumption is less than 30 mW.
Low-power switched-capacitor delta—sigma modulator for EEG recording applications
Jin, Chen; Xu, Zhang; Hongda, Chen
2010-07-01
This paper presents a third-order single-loop delta-sigma modulator of a biomedical micro-system for portable electroencephalogram (EEG) monitoring applications. To reduce the power consumption, the loop filter of the proposed modulator is implemented by applying a switched-capacitor structure. The modulator is designed in a 0.35-μm 2P4M standard CMOS process, with an active area of 365 × 290 μm2. Experimental results show that this modulator achieves a 68 dB dynamic range with an input sinusoidal signal of 100 Hz signal bandwidth under a 64 over-sampling ratio. The whole circuit consumes 515 μW under a 2.5 V power supply, which is suitable for portable EEG monitoring.
Digital Repository Service at National Institute of Oceanography (India)
Somayajulu, B.L.K.; Bhushan, R.; Narvekar, P.V.
ppt, as revealed by the GEOSECS data (1977-78). The delta sup(14)C-sigma CO sub(2)-salinity relationships show better correlation in the western sector. High biological productivity induced changes and corrosive deepwaters could account for sigma CO...
The use of variable-step delta modulation in digital filtering and correlation analysis
Pogribnoi, V. A.
1985-11-01
General expressions are obtained for convolutions and correlation functions using variable-quantization-step DM in conjunction with PCM, making it possible to realize low-cost processor circuits. Algorithms for the operation of processors for digital filtering and correlation analysis on the basis of this type of modulation are proposed. In addition, they are compared with algorithms for the operation of processors with linear PCM, DM, and delta-sigma modulation.
A low-power triple-mode sigma-delta DAC for reconfigurable (WCDMA/ TD-SCDMA/GSM) transmitters*
Institute of Scientific and Technical Information of China (English)
Qiu Dong; Yi Ting; Hong Zhiliang
2011-01-01
A sigma-delta (ΣΔ) DAC with channel filtering for multi-standard wireless transmitters used in the software-defined-radio (SDR) system is presented. The conversion frequency, transfer function of the digital filter and the ΣΔ modulator, word-length of the IDAC and cut-off frequency of the analog reconstruction filter can be digitally programmed to satisfy specifications of WCDMA, TD-SCDMA and GSM standards. The Σ Δ DAC fabricated in SMIC 0.13-μm CMOS process occupies a die area of 0.72 mm2, while consuming 5.52/4.82/3.04 mW in WCDMA/TD-SCDMA/GSM mode from a single 1.2-V supply voltage. The measured SFDR is 62.8/60.1/ 75.5 dB for WCDMA/TD-SCDMA/GSM mode, respectively.
Design of a Low-Light-Level Image Sensor with On-Chip Sigma-Delta Analog-to- Digital Conversion
Mendis, Sunetra K.; Pain, Bedabrata; Nixon, Robert H.; Fossum, Eric R.
1993-01-01
The design and projected performance of a low-light-level active-pixel-sensor (APS) chip with semi-parallel analog-to-digital (A/D) conversion is presented. The individual elements have been fabricated and tested using MOSIS* 2 micrometer CMOS technology, although the integrated system has not yet been fabricated. The imager consists of a 128 x 128 array of active pixels at a 50 micrometer pitch. Each column of pixels shares a 10-bit A/D converter based on first-order oversampled sigma-delta (Sigma-Delta) modulation. The 10-bit outputs of each converter are multiplexed and read out through a single set of outputs. A semi-parallel architecture is chosen to achieve 30 frames/second operation even at low light levels. The sensor is designed for less than 12 e^- rms noise performance.
Design of a Low-Light-Level Image Sensor with On-Chip Sigma-Delta Analog-to- Digital Conversion
Mendis, Sunetra K.; Pain, Bedabrata; Nixon, Robert H.; Fossum, Eric R.
1993-01-01
The design and projected performance of a low-light-level active-pixel-sensor (APS) chip with semi-parallel analog-to-digital (A/D) conversion is presented. The individual elements have been fabricated and tested using MOSIS* 2 micrometer CMOS technology, although the integrated system has not yet been fabricated. The imager consists of a 128 x 128 array of active pixels at a 50 micrometer pitch. Each column of pixels shares a 10-bit A/D converter based on first-order oversampled sigma-delta (Sigma-Delta) modulation. The 10-bit outputs of each converter are multiplexed and read out through a single set of outputs. A semi-parallel architecture is chosen to achieve 30 frames/second operation even at low light levels. The sensor is designed for less than 12 e^- rms noise performance.
The design of adaptive sigma-delta A/D converter
Institute of Scientific and Technical Information of China (English)
Feng Hui; Lin Zhenghui
2005-01-01
The signal to noise vatio (SNR) of conventional sigma delta analog to digital converter (ΣΔADC) reduces with input signal strength. The existing concept of adaptive quantization is applied to the design of ΣΔADC to improve SNR with high dynamic range. An adaptive algorithm and its circuit implementation is proposed. Because of the error due to the circuit implementation,an error self-calibration circuit is also designed. Simulation results indicate that SNR can be nearly independent of the signal strength.
Sobolev Duals for Random Frames and Sigma-Delta Quantization of Compressed Sensing Measurements
Güntürk, S; Saab, R; Y\\ilmaz, Ö
2010-01-01
Quantization of compressed sensing measurements is typically justified by the robust recovery results of Cand\\`es, Romberg and Tao, and of Donoho. These results guarantee that if a uniform quantizer of step size $\\delta$ is used to quantize $m$ measurements $y = \\Phi x$ of a $k$-sparse signal $x \\in \\R^N$, where $\\Phi$ satisfies the restricted isometry property, then the approximate recovery $x^#$ via $\\ell_1$-minimization is within $O(\\delta)$ of $x$. The simplest and commonly assumed approach is to quantize each measurement independently. In this paper, we show that if instead an $r$th order $\\Sigma\\Delta$ quantization scheme with the same output alphabet is used to quantize $y$, then there is an alternative recovery method via Sobolev dual frames which guarantees a reduction of the approximation error by a factor of $(m/k)^{(r-1/2)\\alpha}$ for any $0 < \\alpha < 1$, if $m \\gtrsim_r k (\\log N)^{1/(1-\\alpha)}$. The result holds with high probability on the initial draw of the measurement matrix $\\Phi$ f...
基于ARM Integrator的Sigma-Delta音频DAC的实现%Implementation of Sigma-Delta Audio DAC Based on ARM Integrator
Institute of Scientific and Technical Information of China (English)
于芳玲; 闫华; 钟锐
2007-01-01
介绍了ARM公司的一款FPGA验证开发平台ARM Integrator,以及基于该平台设计的Sigma-Delta音频DAC的实现.在详细介绍Integrator的各个模块的基础之上,利用开发平台的FPGA上验证实现了一个1阶的6位的Sigma-Delta型的DAC,主要包括Sigma-Delta DAC的原理与主要电路,FPGA验证实现过程中的DAC数字滤波器以及调制器的设计以及验证流程,通过virsim仿真时序波形,验证了所设计的DAC正确性和可实现性.
FPGA based sigma –Delta analogue to digital converter design
Directory of Open Access Journals (Sweden)
P. A. Uchagaonkar
2012-03-01
Full Text Available This paper reports design and development of modified Sigma- Delta ADC realized in FPGA paradigm. The wide gain of this ADC makes it a potential candidate in data converter applications in wide ranging domains such as communication systems, instrumentation, precision measurement devices and manyothers wherein the high resolution precision converter is essential. The proposed architecture encompasses of mixed mode design in which few of the analog and up to 90% digital blocks have been realized on a single platform. The digital building blocks have been tested and implemented in Xilinx ISE with the help of MATLAB system generator tool and instantiated on Spartan 3e FPGA. System performance has been ascertained using the hardware co-simulation and further post verified on the Xilinx analyzer tool.
A 0.9-V switched-opamp-based delta-sigma ADC with dual cycle shift DWA
Institute of Scientific and Technical Information of China (English)
Zhao Jinchen; Zhao Menglian; Wu Xiaobo; Wang Hanqing
2013-01-01
This paper presents a low-power high-precision switched-opamp (SO)-based delta-sigma (△ ∑) analogto-digital converter (ADC).The proposed SO design allows circuit operation at sub-1 V supply voltage,only needs to work in half of a clock cycle,and thus is suitable for low power applications.In addition,an opamp-sharing technique is applied to save on hardware overheads.Due to the use of a dual cycle shift data weighted averaging (DCS-DWA) technique,mismatch errors caused in the feedback DAC have been eliminated without introducing signal-dependent tones.The proposed ADC has been implemented in a standard 0.18μm process and measured to have a 92.2 dB peak SNDR and 94.1 dB dynamic range with 25 kHz signal bandwidth.The power consumption is 58 μW for the modulator at 0.9 V supply voltage and 96 μW for the decimation filter,which translate to the figure-of-merit (FOM) of 35.4 fJ/step for the solo modulator,and 94 fJ/step for the whole system.
Pixel-level continuous-time incremental sigma-delta A/D converter for THz sensors
Khatib, Moustafa; Perenzoni, Matteo
2016-04-01
A readout channel based on continuous-time incremental sigma-delta analog-to-digital converter for FET-based terahertz (THz) imaging applications was implemented in a 0.15 μm standard CMOS technology. The designed readout circuit is suitable for implementation in pixel arrays due to its compact size and power consumption. The system-level analysis used to define the modulator parameters and to specify its analog building blocks is presented. The loop filter has been realized by using a Gm-C integrator. Circuit linearization techniques have been implemented to improve the linearity of the transconductor cell and reduce the impact of parasitic capacitances. Moreover, chopper stabilization technique is adopted in the loop filter, significantly reducing the low-frequency flicker noise thereby preserving the Noise Equivalent Power (NEP) of the FET detector within the required specifications of minimum detectable signal. The resulting input referred noise voltage is 87.5 nV/√Hz . The incremental ADC achieves 68-dB peak signal-to-noise-and-distortion-ratio (SNDR), equivalent to 11 bits effective resolution over 1 kHz signal bandwidth at 1 MHz sampling frequency. In order to meet the requirements of large sensor arrays, a first order architecture is realized. This leads to lower area occupancy and power consumption. The readout circuit draws 80 μW of power from a supply voltage of 1.8 V. The channel occupies an area of 90 x 273μm2.
Adjustable Nyquist-rate System for Single-Bit Sigma-Delta ADC with Alternative FIR Architecture
Frick, Vincent; Dadouche, Foudil; Berviller, Hervé
2016-09-01
This paper presents a new smart and compact system dedicated to control the output sampling frequency of an analogue-to-digital converters (ADC) based on single-bit sigma-delta (ΣΔ) modulator. This system dramatically improves the spectral analysis capabilities of power network analysers (power meters) by adjusting the ADC's sampling frequency to the input signal's fundamental frequency with a few parts per million accuracy. The trade-off between straightforwardness and performance that motivated the choice of the ADC's architecture are preliminary discussed. It particularly comes along with design considerations of an ultra-steep direct-form FIR that is optimised in terms of size and operating speed. Thanks to compact standard VHDL language description, the architecture of the proposed system is particularly suitable for application-specific integrated circuit (ASIC) implementation-oriented low-power and low-cost power meter applications. Field programmable gate array (FPGA) prototyping and experimental results validate the adjustable sampling frequency concept. They also show that the system can perform better in terms of implementation and power capabilities compared to dedicated IP resources.
Low Power Continuous-Time Delta-Sigma ADC with Current Output DAC
DEFF Research Database (Denmark)
Marker-Villumsen, Niels; Jørgensen, Ivan Harald Holger; Bruun, Erik
2015-01-01
The paper presents a continuous-time (CT) DeltaSigma (∆Σ) analog-to-digital converter (ADC) using a current output digital-to-analog converter (DAC) for the feedback. From circuit analysis it is shown that using a current output DAC makes it possible to relax the noise requirements of the 1st...... integrator of the loopfilter, and thereby reduce the current consumption. Furthermore, the noise of the current output DAC being dependent on the ADC input signal level, enabling a dynamic range that is larger than the peak signal-to-noise ratio (SNR). The current output DAC is used in a 3rd order multibit...... CT ∆Σ ADC for audio applications, designed in a 0.18 µm CMOS process, with active-RC integrators, a 7-level Flash ADC quantizer and current output DAC for the feedback. From simulations the ADC achieves a dynamic range of 95.0 dB in the audio band, with a current consumption of 284 µA for a 1.7 V...
Radiation-tolerant delta-sigma time-to-digital converters
Cao, Ying; Steyaert, Michiel
2015-01-01
This book focuses on the design of a Mega-Gray (a standard unit of total ionizing radiation) radiation-tolerant ps-resolution time-to-digital converter (TDC) for a light detection and ranging (LIDAR) system used in a gamma-radiation environment. Several radiation-hardened-by-design (RHBD) techniques are demonstrated throughout the design of the TDC and other circuit techniques to improve the TDC's resolution in a harsh environment are also investigated. Readers can learn from scratch how to design a radiation-tolerant IC. Information regarding radiation effects, radiation-hardened design techniques and measurements are organized in such a way that readers can easily gain a thorough understanding of the topic. Readers will also learn the design theory behind the newly proposed delta-sigma TDC. Readers can quickly acquire knowledge about the design of radiation-hardened bandgap voltage references and low-jitter relaxation oscillators, which are introduced in the content from a designer's perspective. · �...
Institute of Scientific and Technical Information of China (English)
赵迎新; 向坤; 李艳红; 吴虹
2012-01-01
UWB-OFDM (ultra wide band and orthogonal frequency division multiplexing) in wireless communication systems offers several advantages, including robustness to multi-path interference, low power consumption and wide bandwidth. According to the signal characteristics, a novel sigma-delta modulator based on time domain interpolation and decimation was designed for multi-band OFDM-UWB signal conversion. The time domain interpolation resulted in the gaps between sub-carriers. The outputs of sigma-delta modulator were one bit binary streams that carried signal plus quantization noise. The sigma-delta modulator produced zeros in the quantization noise spectrum. These zeros were located at the frequencies of multi-band OFDM-UWB sub-carriers so that the quantization noise filled the gaps in the signal spectrum. Consequently, the presented non-oversampling sigma-delta modulator achieved hardware realization more easily. The large peak-to-average power ratio problem was eliminated in this structure. The time domain interpolation and decimation greatly reduced the complexity and saved the time. Theoretical analysis and simulation results were given to illustrate the validity and feasibility of the modulator.%无线通信系统中,超宽带(UWB)与正交频分复用(OFDM)技术相结合,具有超宽带、低功耗、抗多径衰落等优势.针对多频带OFDM-UWB信号的特点,提出一种基于时域插值和抽取的新型sigma-delta转换器用于完成数据的转换.时域插值使得多频带OFDM-UWB子载波间形成空隙,sigma-delta调制器将输入信号量化为1比特数据流的同时完成量化噪声整形.该sigma-delta调制器在量化噪声频谱中引入位于多频带OFDM-UWB子载波频点上的零点,将大部分量化噪声推到子载波空隙中,达到噪声整形效果.新型sigma-delta调制器采用无过采样结构,使得硬件实现相对容易,同时该结构还避免了OFDM系统的高峰均比问题.对信号进行时域插值与抽取降
Directory of Open Access Journals (Sweden)
Liang Tao
2010-05-01
Full Text Available The prophage is one of the most important components of variable regions in bacterial genomes. Some prophages carry additional genes that may enhance the toxicity and survival ability of their host bacteria. This phenomenon is predominant in Staphylococcus aureus, a very common human pathogen. Bioinformatics analysis of several staphylococcal prophages revealed a highly conserved 40-bp untranslated region upstream of the int gene. A small transcript encoding phage integrase was identified to be initiated from the region, demonstrating that the untranslated region contained a promoter for int. No typical recognition sequence for either sigma(A or sigma(B was identified in the 40-bp region. Experiments both in vitro and in vivo demonstrated that sigma(H recognized the promoter and directed transcription. Genetic deletion of sigH altered the int expression, and subsequently, the excision proportion of prophage DNAs. Phage assays further showed that sigH affected the ability of spontaneous lysis and lysogenization in S. aureus, suggesting that sigH plays a role in stabilizing the lysogenic state. These findings revealed a novel mechanism of prophage integration specifically regulated by a host-source alternative sigma factor. This mechanism suggests a co-evolution strategy of staphylococcal prophages and their host bacteria.
Institute of Scientific and Technical Information of China (English)
张信; 于敦山; 盛世敏; 谭志超
2009-01-01
提出了一种行为级仿真方法,可以用于Sigma-Delta模数转换器系统级和行为级设计.与传统的行为级设计方法相比,该方法拥有更高的速度,更加易于使用,并且对于行为级设计来说有更高的效率.采用这种仿真方法,能详细分析模拟电路单元的非理想特性如积分器、比较器、运算放大器等,有助于实现高性能设计.为了验证该设计方法的有效性,设计了一个二阶Sigma-Delta模数转换器,并采用0.13 μm混合信号CMOS工艺进行了流片.测试结果显示,调制器可以实现77.2 dB的最高信噪比,相当于12.5位量化精度,而功耗仅为5.9 mW(包括抽取滤波器为6.2 mW).%A behavioral simulation method is proposed for both system level and behavioral level design of Sigma-Delta ADCs (analog to digital converters).Compared with traditional behavioral simulation methods,the proposed method has a higher simulating speed and is more efficient in the behavioral design.With this simulation method,the imperfections of the analog cells as integrators,comparator,and the Op-Amps are analyzed in detail,which guides the design towards high performance. As a proof for the effectiveness of this method,a second-order Sigma-Delta modulator was designed and fabricated using a 0.13 μm mixed signal CMOS technology.The test results show that the modulator can achieve a peak SNR of 77.2 dB,which equals to a 12.5 bit resolution,and a power dissipation of 5.9 mW (6.2 mW with decimator) was occupied.
Walch, S. P.; Bauschlicher, C. W., Jr.
1983-01-01
Calculations are performed for the predicted ground states of TiH(4-phi), VH(5-delta), CrH(6-sigma-plus), MnH(7-sigma-plus), Fett(4,6-delta) and NiH(2-delta). For FeH both the 6-delta and 4-delta states are studied, since both are likely candidates for the ground state. The ground state symmetries are predicted based on a combination of atomic coupling arguments and coupling of 4s(2)3d(n) and 4s(1)3d(n+1) terms in the molecular system. Electron correlation is included by a CASSCF/CI (SD) treatment. The CASSCF includes near-degeneracy effects, while correlation of the 3d electrons in included at the CI level.
Sigma-1 Receptor Modulates Neuroinflammation After Traumatic Brain Injury.
Dong, Hui; Ma, Yunfu; Ren, Zengxi; Xu, Bin; Zhang, Yunhe; Chen, Jing; Yang, Bo
2016-07-01
Traumatic brain injury (TBI) remains a significant clinical problem and contributes to one-third of all injury-related deaths. Activated microglia-mediated inflammatory response is a distinct characteristic underlying pathophysiology of TBI. Here, we evaluated the effect and possible mechanisms of the selective Sigma-1 receptor agonist 2-(4-morpholinethyl)-1-phenylcyclohexanecarboxylate (PRE-084) in mice TBI model. A single intraperitoneal injection 10 μg/g PRE-084, given 15 min after TBI significantly reduced lesion volume, lessened brain edema, attenuated modified neurological severity score, increased the latency time in wire hang test, and accelerated body weight recovery. Moreover, immunohistochemical analysis with Iba1 staining showed that PRE-084 lessened microglia activation. Meanwhile, PRE-084 reduced nitrosative and oxidative stress to proteins. Thus, Sigma-1 receptors play a major role in inflammatory response after TBI and may serve as useful target for TBI treatment in the future.
Institute of Scientific and Technical Information of China (English)
韩雪梅; 彭虎; 杜宏伟; 陈强; 冯焕清
2005-01-01
基于过采样Sigma-delta ADC的波束形成器直接利用过采样Sigma-delta ADC所产生的1bit码流的相位信息进行高质量的聚焦延迟-求和.但此1bit码流速率极高,一般不能直接用USB接口送到计算机进行波束形成等后续处理,须先将其进行无损压缩,即在降低码流速度的同时保留波束形成所需的相位信息.采用Huffman编码方式对高速1bit流进行压缩.结果表明,Huffman编码能实现一半以上的压缩,从而使1bit码流通过USB接口传送成为可能.
DEFF Research Database (Denmark)
Custódio, José R.; Goes, João; Paulino, Nuno
2013-01-01
This paper describes the design and experimental evaluation of a multibit Sigma-Delta (ΣΔ) modulator (ΣΔM) with enhanced dynamic range (DR) through the use of nonlinear digital-to-analog converters (DACs) in the feedback paths. This nonlinearity imposes a trade-off between DR and distortion, which...... is well suited to the intended hearing aid application. The modulator proposed here uses a fully-differential self-biased amplifier and a 4-bit quantizer based on fully dynamic comparators employing MOS parametric pre-amplification to improve both energy and area efficiencies. A test chip was fabricated...
Schilling, D. L.
1975-01-01
Encoding of video signals using adaptive delta modulation (DM) was investigated, along with the error correction of DM encoded signals corrupted by thermal noise. Conversion from pulse code modulation to delta modulation was studied; an expression for the signal to noise ratio of the DM signal derived was achieved by employing linear, 2-sample, interpolation between sample points. A phase locked loop using a nonlinear processor in lieu of a loop filter is discussed.
On the Stability of a Double Integration Delta Modulator
DEFF Research Database (Denmark)
Nielsen, Palle Tolstrup
1971-01-01
A delta modulator with a second-order network in the feedback path is considered. For zero input signal the possible modes of oscillation are determined as a function of the zero of the linear network. The method could be employed with other types of feedback networks. A comparison is made...
Mass splittings in $\\Sigma_b$ and $\\Sigma_b^*$
Rosner, Jonathan L.
2006-01-01
The charged $\\Sigma_b$ and $\\Sigma^*_b$ states have recently been reported by the CDF Collaboration. The relation of their reported charge-averaged masses to expectations based on the quark model is reviewed briefly. A relation is proved among the $\\Delta I = 1$ electromagnetic mass differences $\\Sigma_1 \\equiv M(\\Sigma^+) - M(\\Sigma^-)$, $\\Sigma^*_1 \\equiv M(\\Sigma^{*+})- M(\\Sigma^{*-})$, $\\Sigma_{b1} \\equiv M(\\Sigma_b^+) - M(\\Sigma_b^-)$, and $\\Sigma^*_{b1} \\equiv M(\\Sigma_b^{*+}) - M(\\Sigm...
Allosteric modulation of sigma-1 receptors by SKF83959 inhibits microglia-mediated inflammation.
Wu, Zhuang; Li, Linlang; Zheng, Long-Tai; Xu, Zhihong; Guo, Lin; Zhen, Xuechu
2015-09-01
Recent studies have shown that sigma-1 receptor orthodox agonists can inhibit neuroinflammation. SKF83959 (3-methyl-6-chloro-7,8-hydroxy-1-[3-methylphenyl]-2,3,4,5-tetrahydro-1H-3-benzazepine), an atypical dopamine receptor-1 agonist, has been recently identified as a potent allosteric modulator of sigma-1 receptor. Here, we investigated the anti-inflammatory effects of SKF83959 in lipopolysaccharide (LPS)-stimulated BV2 microglia. Our results indicated that SKF83959 significantly suppressed the expression/release of the pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS), and inhibited the generation of reactive oxygen species. All of these responses were blocked by selective sigma-1 receptor antagonists (BD1047 or BD1063) and by ketoconazole (an inhibitor of enzyme cytochrome c17 to inhibit the synthesis of endogenous dehydroepiandrosterone, DHEA). Additionally, we found that SKF83959 promoted the binding activity of DHEA with sigma-1 receptors, and enhanced the inhibitory effects of DHEA on LPS-induced microglia activation in a synergic manner. Furthermore, in a microglia-conditioned media system, SKF83959 inhibited the cytotoxicity of conditioned medium generated by LPS-activated microglia toward HT-22 neuroblastoma cells. Taken together, our study provides the first evidence that allosteric modulation of sigma-1 receptors by SKF83959 inhibits microglia-mediated inflammation. SKF83959 is a potent allosteric modulator of sigma-1 receptor. Our results indicated that SKF83959 enhanced the activity of endogenous dehydroepiandrosterone (DHEA) in a synergic manner, and inhibited the activation of BV2 microglia and the expression/release of the pro-inflammatory mediators, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), inducible nitric oxide synthase (iNOS).
Dayou, Fabrice; Hernández, Marta I; Campos-Martínez, José; Hernández-Lamoneda, Ramón
2007-05-21
The dynamics of collisional deactivation of O(2)(X (3)Sigma(g) (-),v=20-32) by O(2)(X (3)Sigma(g) (-),v(')=0) is investigated in detail by means of quantum-mechanical calculations. The theoretical approach involves ab initio potential energy surfaces correlating to the X (3)Sigma(g) (-), a (1)Delta(g), and b (1)Sigma(g) (+) states of O(2) and their corresponding spin-orbit couplings [F. Dayou, M. I. Hernandez, J. Campos-Martinez, and R. Hernandez-Lamoneda, J. Chem. Phys. 123, 074311 (2005)]. Accurate Rydberg-Klein-Rees potentials are included in order to improve the description of the vibrational structure of the fragments. The calculated Boltzmann-averaged depletion probabilities display a dependence with v in good agreement with experimental measurements. The onset of the vibrational-to-electronic (V-E) depletion mechanism is noticeable for v>/=26, and it is due to energy transfer to both a (1)Delta(g) and b (1)Sigma(g) (+) states of the diatom. For O(2)(X (3)Sigma(g) (-),v=28), a further and sharp increase in the removal probabilities is caused by a near degeneracy with the O(2)(b (1)Sigma(g) (+),v=19) vibrational state. Analysis of the temperature dependence of the Boltzmann-averaged probabilities indicates a transition from the vibrational-to-translational to the V-E energy transfer regime, which can be traced back to the behavior of the inelastic probabilities as functions of kinetic energy. Furthermore, branching ratios for outcomes through the three different electronic states show a strong propensity towards populating a unique vibrational level within each electronic state. These results provide supported evidence that spin-orbit couplings account for a large portion of the "dark channel" reported in total depletion measurements. New insight for further experimental and theoretical investigations is also given.
New pulse modulator with low switching frequency
Directory of Open Access Journals (Sweden)
Golub V. S.
2014-12-01
Full Text Available The author presents an integrating pulse modulator (analog signal converter with the pulse frequency and duration modulation similar to sigma-delta modulation (with low switching frequency, without quantization. The modulator is characterized by the absence of the quantization noise inherent in sigma-delta modulator, and a low switching frequency, unlike the pulse-frequency modulator. The modulator is recommended, in particular, to convert signals at the input of the class D power amplifier.
Directory of Open Access Journals (Sweden)
Koh Jinseok
2006-01-01
Full Text Available We present a discrete-time second-order multibit sigma-delta ADC that filters and decimates by two the input data samples. At the same time it provides gain control function in its input sampling stage. A 4-tap FIR switched capacitor (SC architecture was chosen for antialiasing filtering. The decimation-by-two function is realized using divided-by-two clock signals in the antialiasing filter. Antialiasing, gain control, and sampling functions are merged in the sampling network using SC techniques. This compact architecture allows operating the preceding blocks at twice the ADC's clock frequency, thus improving the noise performance of the wireless receiver channel and relaxing settling requirements of the analog building blocks. The presented approach has been validated and incorporated in a commercial single-chip Bluetooth radio realized in a 1.5 V 130 nm digital CMOS process. The measured antialiasing filtering shows better than 75 dB suppression at the folding frequency band edge. A 67 dB dynamic range was measured with a sampling frequency of 37.5MHz.
Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning
2014-03-01
Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.
Energy Technology Data Exchange (ETDEWEB)
Madigan, W.P.; Bell, D.A.; Buchanan, J.A.; Calkin, M.M.; Clement, J.M.; Copel, M.; Corcoran, M.D.; Johns, K.A.; Lesikar, J.D.; Miettinen, H.E.; Mutchler, G.S.; Naudet, C.J.; Pepin, G.P.; Phillips, G.C.; Roberts, J.B.; Turpin, S.E.; Hungerford, E.V.; Mayes, B.W.; Hancock, A.D.; Pinsky, L.S.; Sekharan, K.K.; Hollas, C.L.; Riley, P.J.; Allred, J.C.; Bonner, B.E.; Cameron, P.; Linn, S.T.; von Witsch, W.; Furic, M.; Valkovic, V.
1985-03-01
The difference ..delta..sigma/sub T/ = sigma(arrow-downup-arrow)-sigma(up-arrowup-arrow) between the proton-proton total cross sections for protons in pure transverse-spin states, was measured at incident momenta 0.8 to 2.5 GeV/c in experiments performed at the Los Alamos Clinton P. Anderson Meson Physics Facility and the Argonne Zero Gradient Synchrotron. In agreement with other data, peaks were observed at center-of-mass energies of 2.14 and 2.43 GeV/c/sup 2/, where /sup 1/D/sub 2/ and /sup 1/G/sub 4/ dibaryon resonances have been proposed.
Delta-Sigma AD-Converters Practical Design for Communication Systems
Gaggl, Richard
2013-01-01
The emphasis of this book is on practical design aspects for broadband A/D converters for communication systems. The embedded designs are employed for transceivers in the field of ADSL solutions and WLAN applications. An area- and power-efficient realization of a converter is mandatory to remain competitive in the market. The right choice for the converter topology and architecture needs to be done very carefully to result in a competitive FOM. The book begins with a brief overview of basic concepts about ADSL and WLAN to understand the ADC requirements. At architectural level, issues on different modulator topologies are discussed employing the provided technology node. The design issues are pointed out in detail for modern digital CMOS technologies, beginning with 180nm followed by 130nm and going down to 65nm feature size. Beside practical aspects, challenges to mixed-signal design level are addressed to optimize the converters in terms of consumed chip area, power consumption and design for high yield in ...
Energy Technology Data Exchange (ETDEWEB)
Beddo, M.E.
1990-10-01
A measurement off {Delta}{sigma}{sub L}(np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. The results will help determine the isospin-zero (I = 0) scattering amplitudes, which are not well known above laboratory energies of 500 MeV, whereas the isospin-one (I = 1) amplitudes are fairly well-determined to 1 GeV. Data points were taken at the Los Alamos Meson Physics Facility (LAMPF) at Los Alamos, New Mexico, for five neutron beam energies: 484, 568, 634,720 and 788 MeV; they are the first in this energy range. Polarized neutrons were produced by charge-exchange of polarized protons on a liquid deuterium target (LD{sub 2}). Large-volume neutron counters detected the neutrons that passed through a polarized proton target. The counters subtended a range of solid angles large enough to allow extrapolation of the scattered neutrons to 0{degree}. Two modifications to the LAMPF accelerator system which were made for this work are described. They included a beam buncher,'' which modified the normal rf-time structure of the proton beam and allowed for the selection of peak-energy neutrons by time-of-flight means, and a computerized beam steering program, which reduced systematic effects due to beam motion at the LD{sub 2} target. The experimental values of {Delta}{sigma}{sub L}(np) are found to be consistent with other np data, including preliminary data from SIN and Saclay, but not with some results from Argonne which used a polarized proton beam and a polarized deuteron target. The I = 0 component was extracted from {Delta}{sigma}{sub L}(np) using existing pp data (I = 1), with the unexpected result that {Delta}{sigma}{sub L}(I = 0) was found to be essentially identical in shape to {Delta}{sigma}{sub L}(I = 1). The significance of this is not yet understood.
Tortosa, Ramón
2012-01-01
Esta tesis doctoral es el resultado de un conjunto de trabajos de investigación encaminados a sistematizar y optimizar el diseño de convertidores analógico-digitales de tipo Sigma-Delta, realizados mediante técnicas de circuito en tiempo continuo. Para ello, se ha desarrollado una nueva metodología de diseño de alto nivel que está especialmente orientada a topologías de moduladores en cascada. En esencia, el método propuesto consiste en sintetizar el filtro del modulador complementamente e...
Energy Technology Data Exchange (ETDEWEB)
Howle, Chris R.; Arrowsmith, Alan N.; Chikan, Viktor; Leone,Stephen R.
2007-01-18
Fourier transform visible spectroscopy, in conjunction withVUV photons produced by a synchrotron, is employed to investigate thephotodissociation of CH3CN. Emission is observed from both theCN(B2Sigma+ - X2Sigma+) and CH(A2Delta - X2PI) transitions; only theformer is observed in spectra recorded at 10.2 and 11.5 eV, whereas bothare detected in the 16 eV spectrum. The rotational and vibrationaltemperatures of both the CN(B2Sigma+) and CH(A2Delta) radical productsare derived using a combination of spectral simulations and Boltzmannplots. The CN(B2Sigma+) fragment displays a bimodal rotationaldistribution in all cases. Trot(CN(B2Sigma+)) ranges from 375 to 600 K atlower K' and from 1840 to 7700 K at higher K' depending on the photonenergy used. Surprisal analyses indicate clear bimodal rotationaldistributions, suggesting CN(B2Sigma+) is formed via either linear orbent transition states, respectively, depending on the extent ofrotational excitation in this fragment. CH(A2Delta) has a singlerotational distribution when produced at 16 eV which results inTrot(CH(A2Delta)) = 4895 +- 140 K in nu' = 0 and 2590 +- 110 K in nu' =1. From thermodynamic calculations, it is evident that CH(A2Delta) isproduced along with CN(X2Sigma+) + H2. These products can be formed by atwo step mechanism (via excited CH3* and ground state CN(X2Sigma+) or aprocess similar to the "roaming" atom mechanism; the data obtained hereare insufficient to definitively conclude whether either pathway occurs.A comparison of the CH(A2Delta) and CN(B2Sigma+) rotational distributionsproduced by 16 eV photons allows the ratio between the two excitedfragments at this energy to be determined. An expression that considersthe rovibrational populations of both band systems results in aCH(A2Delta):CN(B2Sigma+) ratio of (1.2 +- 0.1):1 at 16 eV, therebyindicating that production of CH(A2Delta) is significant at 16eV.
Energy Technology Data Exchange (ETDEWEB)
Neidel, Andreas; Fischer, Boromir; Riesenbeck, Susanne; Cagliyan, Erhan [Siemens AG, Berlin (Germany). Werkslaboratorien
2014-04-01
A service temperature increase of turbine exhaust casing liners of heavy-duty industrial gas turbines, driven by the need to raise thermal efficiencies, motivated a number of ageing trials. Casing liners are often made of metastable austenitic stainless steels, suitable for high temperature applications. Alloys such as 321SS and 347SS might contain, in the as-cast condition, rather large amounts of delta ferrite, if not further processed by rolling or forging, easily in excess of 15 %. Even rolled sheet and bar might contain significant volume fractions of that phase if welded, up to 15 % or so in the heat affected zone (HAZ) immediately adjacent to the fusion line, and in the weld metal. It is known from the literature and from field experience that delta ferrite might decompose into sigma phase after long-term service exposure at elevated temperatures. This may embrittle the material and can be detrimental to mechanical properties. It could also deleteriously affect creep strength. The main aim of ageing trials described in this paper was to study the phase stability of delta ferrite under simulated service conditions. The results are correlated to metallographic testing results, obtained from examining actual service components of heavy-duty gas turbine engines in the field. (orig.)
Bhutada, Pravinkumar S; Mundhada, Yogita R; Ghodki, Yogesh R; Chaware, Parag; Dixit, Pankaj V; Jain, Kishor S; Umathe, Sudhir N
2012-02-01
Sigma-1 receptor agonists are reported to augment and antagonists block the rewarding effects of drugs of abuse. However, their effect on reinstatement of ethanol-induced conditioned place preference (CPP) has not yet been explored. Therefore, we investigated the ability of 2-(4-morpholino)ethyl-1-phenylcyclohexane-1-carboxylate (PRE-084), a sigma-1 receptor agonist, and N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino) ethylamine dihydrobromide (BD-1047), a sigma-1 receptor antagonist, on the acquisition, expression, and reinstatement of ethanol-induced CPP using adult male Swiss mice. BD-1047 (0.1-10 μg/mouse, intracerebroventricularly) dose-dependently blocked the development, expression, and reinstatement of ethanol-induced CPP, and PRE-084 (0.01-10 μg/mouse, intracerebroventricularly) dose-dependently reinstated the extinguished response. These effects of PRE-084 and BD-1047 alone or in combination with ethanol did not influence the motor activity. Therefore, it is concluded that sigma-1 receptor ligands can modulate the acquisition, expression, and reinstatement of conditioned reinforcing effects of ethanol with no reinforcing or aversive influence of their own. The results add to the growing literature on sigma-1 receptor modulation in the pharmacotherapy of ethanol addiction.
Custodio, José R; Goes, João; Paulino, Nuno; Oliveira, João P; Bruun, Erik
2013-06-01
This paper describes the design and experimental evaluation of a multibit Sigma-Delta (ΣΔ) modulator (ΣΔM) with enhanced dynamic range (DR) through the use of nonlinear digital-to-analog converters (DACs) in the feedback paths. This nonlinearity imposes a trade-off between DR and distortion, which is well suited to the intended hearing aid application. The modulator proposed here uses a fully-differential self-biased amplifier and a 4-bit quantizer based on fully dynamic comparators employing MOS parametric pre-amplification to improve both energy and area efficiencies. A test chip was fabricated in a 130 nm digital CMOS technology, which includes the proposed modulator with nonlinear DACs and a modulator with conventional linear DACs, for comparison purposes. The measured results show that the ΣΔM using nonlinear DACs achieves an enhancement of the DR around 8.4 dB (to 91.4 dB). Power dissipation and silicon area are about the same for the two cases. The performance achieved is comparable to that of the best reported multibit ΣΔ ADCs, with the advantage of occupying less silicon area (7.5 times lower area when compared with the most energy efficient ΣΔM).
Domínguez Suárez, Marcos
2013-01-01
La adquisición de señales biomédicas requiere de convertidores analógico a digital de alta resolución, baja tensión de alimentación y bajo consumo. La solución para esta necesidad es el uso de nuevas arquitecturas de conversión sigma delta como la presentada en este proyecto de fin de carrera, que resulta de la combinación de un modulador sigma delta con un cuantificador de doble rampa. Este proyecto de fin de carrera abarca la fase de implementación en un circuito integrado CMOS del siste...
Amplitude modulation in $\\delta$ Sct stars: statistics from an ensemble study of Kepler targets
Bowman, Dominic M; Breger, Michel; Murphy, Simon J; Holdsworth, Daniel L
2016-01-01
We present the results of a search for amplitude modulation of pulsation mode frequencies in 983 $\\delta$ Sct stars, which have effective temperatures between 6400 $\\leq T_{\\rm eff} \\leq$ 10 000 K in the Kepler Input Catalogue and were continuously observed by the Kepler Space Telescope for 4 yr. We demonstrate the diversity in pulsational behaviour observed, in particular nonlinearity, which is predicted for $\\delta$ Sct stars. We analyse and discuss examples of $\\delta$ Sct stars with constant amplitudes and phases; those that exhibit amplitude modulation caused by beating of close-frequency pulsation modes; those that exhibit pure amplitude modulation (with no associated phase variation); those that exhibit phase modulation caused by binarity; and those that exhibit amplitude modulation caused by nonlinearity. Using models and examples of individual stars, we demonstrate that observations of the changes in amplitude and phase of pulsation modes can be used to distinguish among the different scenarios. We f...
Photonic Front-End and Comparator Processor for a Sigma-Delta Modulator
2008-09-01
bipolar transistor (HBT) technology would need to be demonstrated for an on-chip integrated circuit design. 40 THIS PAGE INTENTIONALLY LEFT BLANK 41...MODELS USED .MODEL QX PNP (BF=34.188) .MODEL QY PNP (BF=32.52) .MODEL DX D(N=0.001 TT=1E-15) .MODEL NMOS NMOS(KP=1 TOX=100U VTO=0.39 W
A digital filter for an analog-digital converter with delta-sigma modulation
Beliavskaia, T. G.; Levchuk, Iu. P.; Strigina, E. V.
1986-05-01
Various methods of implementing the digital versions of analog-digital converters are examined, with attention given to homogeneous, triangular, and low-frequency digital filters. A comparison of the implementations proposed here makes it possible to optimize the structure of an analog-digital converter with respect to the hardware costs depending on the required accuracy.
Joo, K; Aznauryan, I G; Burkert, V D; Minehart, R C; Adams, G; Ambrozewicz, P; Anciant, E; Anghinolfi, M; Asavapibhop, B; Asryan, G; Audit, G; Auger, T; Avakian, H; Bagdasaryan, H; Ball, J P; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bektasoglu, M; Benmouna, N; Bianchi, N; Biselli, A S; Boiarinov, S; Bonner, B E; Bouchigny, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Butuceanu, C; Calarco, J R; Carman, D S; Carnahan, B; Cetina, C; Chen, S; Ciciani, L; Cole, P L; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Cummings, J P; De Sanctis, E; De Vita, R; Degtyarenko, P V; Dennis, L; Deur, A; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Doughty, D; Dragovitsch, P; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; Elouadrhiri, L; Empl, A; Eugenio, P; Fersch, R; Feuerbach, R J; Forest, T A; Funsten, H; Gaff, S J; Garçon, M; Gavalian, G; Gilad, S; Gilfoyle, G P; Giovanetti, K L; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M R; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hu, J; Hyde-Wright, C E; Ilieva, Y; Ireland, D; Ito, M M; Jenkins, D; Jüngst, H G; Kellie, J D; Kelley, J H; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Klusman, M; Kossov, M; Koubarovski, V; Kramer, L H; Kuhn, S E; Kühn, J; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Livingston, K; Lukashin, K; Manak, J J; Marchand, C; McAleer, S; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mikhailov, K; Mirazita, M; Miskimen, R; Mokeev, V; Morand, L; Morrow, S A; Muccifora, V; Müller, J; Mutchler, G S; Napolitano, J; Nasseripour, R; Nelson, S O; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E A; Peterson, G; Philips, S A; Pivnyuk, N; Pocanic, D; Pogorelko, O I; Polli, E; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatie, F; Sabourov, K; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabyan, Yu G; Shaw, J; Simionatto, S; Skabelin, A V; Smith, E S; Sober, D I; Spraker, M; Stavinsky, A V; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Taylor, S; Tedeschi, D J; Thoma, U; Thompson, R; Tkabladze, A; Todor, L; Tur, C; Ungaro, M; Vineyard, M F; Vlassov, A V; Wang, K; Weinstein, L B; Weller, H; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L
2004-01-01
The polarized longitudinal-transverse structure function $\\sigma_{LT^\\prime}$ has been measured using the $p(\\vec e,e'\\pi^+)n$ reaction in the $\\Delta(1232)$ resonance region at $Q^2=0.40$ and 0.65 GeV$^2$. No previous $\\sigma_{LT^\\prime}$ data exist for this reaction channel. The kinematically complete experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. A partial wave analysis of the data shows generally better agreement with recent phenomenological models of pion electroproduction compared to the previously measured $\\pi^0 p$ channel. A fit to both $\\pi^0 p$ and $\\pi^+ n$ channels using a unitary isobar model suggests the unitarized Born terms provide a consistent description of the non-resonant background. The $t$-channel pion pole term is important in the $\\pi^0 p$ channel through a rescattering correction, which could be model-dependent.
Chackerian, C., Jr.; Guelachvili, G.; Lopez-Pineiro, A.; Tipping, R. H.
1989-01-01
The vibrational transition dipole moment for the highly reactive radical species NH in its ground electronic state is obtained via the Herman-Wallis effect manifest in emission spectra produced in a plasma reactor. The results of these experiments on the five lowest Delta V = 1 bands are in good agreement with high quality ab initio calculations of the electric dipole moment function.
Horikoshi, Mina; Yura, Takashi; Tsuchimoto, Sachie; Fukumori, Yoshihiro; Kanemori, Masaaki
2004-11-01
Escherichia coli heat shock transcription factor sigma32 is rapidly degraded in vivo, with a half-life of about 1 min. A set of proteins that includes the DnaK chaperone team (DnaK, DnaJ, GrpE) and ATP-dependent proteases (FtsH, HslUV, etc.) are involved in degradation of sigma32. To gain further insight into the regulation of sigma32 stability, we isolated sigma32 mutants that were markedly stabilized. Many of the mutants had amino acid substitutions in the N-terminal half (residues 47 to 55) of region 2.1, a region highly conserved among bacterial sigma factors. The half-lives ranged from about 2-fold to more than 10-fold longer than that of the wild-type protein. Besides greater stability, the levels of heat shock proteins, such as DnaK and GroEL, increased in cells producing stable sigma32. Detailed analysis showed that some stable sigma32 mutants have higher transcriptional activity than the wild type. These results indicate that the N-terminal half of region 2.1 is required for modulating both metabolic stability and the activity of sigma32. The evidence suggests that sigma32 stabilization does not result from an elevated affinity for core RNA polymerase. Region 2.1 may, therefore, be involved in interactions with the proteolytic machinery, including molecular chaperones.
Delta-N formalism for curvaton with modulated decay
Energy Technology Data Exchange (ETDEWEB)
Kohri, Kazunori [Cosmophysics group, Theory Center, IPNS, KEK, and The Graduate University for Advanced Study (Sokendai), Tsukuba 305-0801 (Japan); Lin, Chia-Min [Department of Physics, Kobe University, Kobe 657-8501 (Japan); Matsuda, Tomohiro, E-mail: kohri@post.kek.jp, E-mail: cmlin@boar.kobe-u.ac.jp, E-mail: matsuda@sit.ac.jp [Laboratory of Physics, Saitama Institute of Technology, Fukaya, Saitama 369-0293 (Japan)
2013-06-01
In this paper, the curvature perturbation generated by the modulated curvaton decay is studied by a direct application of δN-formalism. Our method has a sharp contrast with the non-linear formalism which may be regarded as an indirect usage of δN-formalism. We first show that our method can readily reproduce results in previous works of modulation of curvaton. Then we move on to calculate the case where the curvaton mass (and hence also the decay rate) is modulated. The method can be applied to the calculation of the modulation in the freezeout model, in which the heavy species are considered instead of the curvaton. Our method explains curvaton and various modulation on an equal footing.
A 3rd Order Low Power SI Sigma-Delta A/D Converter for Voice-Band Applications
DEFF Research Database (Denmark)
Jørgensen, Ivan Herald Holger; Bogason, Gudmundur
1997-01-01
This paper presents a 3rd order switched current-ΣΔ-modulator. The ΣΔ-modulator operates at a sampling rate of fs=600 kHz and the signal band is fb=5.5 kHz, i.e., an oversampling factor of R=54.5 is used. Multiple input signals are used to reduce the internal signal swings which results in reduced...
Ancona, Veronica; Li, Wenting; Zhao, Youfu
2014-01-01
In Erwinia amylovora, ECF (extracytoplasmic functions) alternative sigma factor HrpL regulates the transcription of hrp (hypersensitive response and pathogenicity)-type III secretion system (T3SS) genes by binding to a consensus sequence known as the hrp box in hrp gene promoters. In turn, the expression of hrpL has been proposed to be positively controlled by alternative sigma factor 54 (σ(54)) (RpoN) and HrpS, a member of the σ(54) enhancer-binding proteins (EBPs). However, the function of RpoN has not been characterized genetically in E. amylovora. In this study, we investigated the role of RpoN, a nitrogen limitation sigma factor, and its modulation protein YhbH, a novel ribosome-associated protein, in E. amylovora virulence. Our results showed that mutations in hrpS, hrpL, rpoN and yhbH, but not yfiA and rmf3, resulted in a nonpathogenic phenotype on immature pear fruits and apple shoots. Consistently, the expression of T3SS genes, including hrpL, dspE, hrpN and hrpA, was barely detected in hrpS, hrpL, rpoN and yhbH mutants. These mutants were also not capable of eliciting a hypersensitive response (HR) on tobacco; however, the overexpression of hrpL using an inducible promoter rescued the HR-eliciting abilities of these mutants. These results suggest that a sigma factor cascade exists in the regulatory networks of E. amylovora and regulates important virulence factors. On the basis of this study and previously reported data, a model is proposed for the regulation of T3SS in E. amylovora.
Interleaved IIR filter on Δ-Σ modulated signals
Lewis, David M.
1996-10-01
This paper describes a circuit implementing 12 fully independent biquad digital filters operating on (Delta) - (Sigma) modulated signals with 28 b resolution. A carry-save adder with partial carry propagation (Delta) -(Sigma) modulator is used together with a pipelined architecture that interleaves all of the filters on a single datapath. Implemented in TSPC logic, the circuit comprises 95 K transistors, including a variable frequency on-chip clock generator.
Been, M.W.H.J. de; Francke, C.; Siezen, R.J.; Abee, T.
2011-01-01
A common bacterial strategy to cope with stressful conditions is the activation of alternative sigma factors that control specific regulons enabling targeted responses. In the human pathogen Bacillus cereus, activation of the major stress-responsive sigma factor sigma(B) is controlled by a signallin
Energy Technology Data Exchange (ETDEWEB)
Kyungseon Joo; L.C. Smith; V.D. Burkert; R. Minehart
2003-05-01
The polarized longitudinal-transverse structure function {sigma}{sub LT'} has been measured for the first time in the {Delta}(1232) resonance region at Q{sup 2} = 0.40 and 0.65 GeV{sup 2}. Data for the p{rvec e},e'p {pi}{sup 0} reaction were taken at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. Evidence for interference between resonant and non-resonant amplitudes is discussed using a partial wave analysis. Comparison with previous beam asymmetry measurements at MAMI indicate a deviation from the predicted Q{sup 2} dependence of {sigma}{sub LT'} using recent phenomenological models.
Patón Álvarez, Susana
2004-01-01
Los moduladores Sigma-Delta de tiempo continuo constituyen una técnica de conversión de señal analógica a señal digital que resulta ser una alternativa interesante para aplicaciones de alta velocidad. Comparado con otras alternativas, son especialmente insensibles a las imperfecciones del circuito y a las tolerancias de los componentes, pero tradicionalmente se han diseñado para aplicaciones de baja-media velocidad. Esta tesis aporta contribuciones al análisis y modelado de moduladores Si...
Optimal space communications techniques. [discussion of video signals and delta modulation
Schilling, D. L.
1974-01-01
The encoding of video signals using the Song Adaptive Delta Modulator (Song ADM) is discussed. The video signals are characterized as a sequence of pulses having arbitrary height and width. Although the ADM is suited to tracking signals having fast rise times, it was found that the DM algorithm (which permits an exponential rise for estimating an input step) results in a large overshoot and an underdamped response to the step. An overshoot suppression algorithm which significantly reduces the ringing while not affecting the rise time is presented along with formuli for the rise time and the settling time. Channel errors and their effect on the DM encoded bit stream were investigated.
Directory of Open Access Journals (Sweden)
Eric B Emmons
2016-04-01
Full Text Available Organizing movements in time is a critical and highly conserved feature of mammalian behavior. Temporal control of action requires corticostriatal networks. We investigate these networks in rodents using a two-interval timing task while recording local field potentials in medial frontal cortex or dorsomedial striatum. Consistent with prior work, we found cue-triggered delta (1-4 Hz and theta activity (4-8 Hz primarily in rodent medial frontal cortex. We observed delta activity across temporal intervals in medial frontal cortex and dorsomedial striatum. Rewarded responses were associated with increased delta activity in medial frontal cortex. Activity in theta bands in medial frontal cortex and delta bands in the striatum was linked with the timing of responses. These data suggest both delta and theta activity in frontostriatal networks are modulated during interval timing and that activity in these bands may be involved in the temporal control of action.
Anticic, T; Bartke, J; Beck, H; Betev, L; Bialkowska, H; Blume, C; Boimska, B; Book, J; Botje, M; Buncic, P; Christakoglou, P; Chung, P; Chvala, O; Cramer, J; Eckardt, V; Fodor, Z; Foka, P; Friese, V; Gazdzicki, M; Grebieszkow, K; Hohne, C; Kadija, K; Karev, A; Kolesnikov, V; Kowalski, M; Kresan, D; Laszlo, A; Lacey, R; van Leeuwen, M; Mackowiak-Pawlowska, M; Makariev, M; Malakhov, A; Melkumov, G; Mitrovski, M; Mrowczynski, S; Palla, G; Panagiotou, A; Pluta, J; Prindle, D; Puhlhofer, F; Renfordt, R; Roland, C; Roland, G; Rybczynski, M; Rybicki, A; Sandoval, A; Rustamov, A; Schmitz, N; Schuster, T; Seyboth, P; Sikler, F; Skrzypczak, E; Slodkowski, M; Stefanek, G; Stock, R; Strobele, H; Susa, T; Szuba, M; Varga, D; Vassiliou, M; Veres, G; Vesztergombi, G; Vranic, D; Wlodarczyk, Z; Wojtaszek-Szwarc, A
2015-01-01
Results from the NA49 experiment at the CERN SPS are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb+Pb interactions at beam momenta 20$A$, 30$A$, 40$A$, 80$A$, and 158$A$ GeV/c, as well as in systems of different size ($p+p$, C+C, Si+Si, and Pb+Pb) at 158$A$ GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure $\\Phi_{p_T}$ by a study of the recently proposed strongly intensive measures of fluctuations $\\Delta[P_T, N]$ and $\\Sigma[P_T, N]$. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both $\\Delta[P_T, N]$ and $\\Sigma[P_T, N]$, with the largest values measured in peripheral Pb+Pb interactions. The results are compared with NA61/SHINE measurements in $p+p$ collisions, as well as with predictions of the UrQMD and ...
Energy Technology Data Exchange (ETDEWEB)
Heijboer, Aart; /Pennsylvania U.
2007-10-01
The author discusses results from the Tevatron experiments on mixing and CP-violation in B{sub s} mesons, including the observation of B{sub s} oscillations and the first precision measurement of the mixing frequency, as well as a measurement of the lifetime difference {Delta}{Lambda}{sub s} and the first measurement of the CP-violating phase {delta}{sub s}. The author also briefly reports on the observation of four new bottom baryons at CDF.
Energy Technology Data Exchange (ETDEWEB)
Fuersch, Jonathan
2014-10-16
In DELTA especially at high beam currents often the occurence of an instability of a longitudinal oscillation mode is observed. In the framework of the present thesis first with different procedure the cause of the longitudinal oscillation mode, which is especially strongly excited at high beam currents, is searched for. Thereby connections between the occurrence of this mode and parameters from the region of the storage-ring high-frequency system is observed. It is shown by comparison of different procedures, simulation calculations, and experimental pre-examinations, that especially by a phase modulation of the storage-ring high frequency an essential improvement of especially the longitudinal beam stability and the beam lifetime can be reached. For the durable and reliable improvement of these beam properties in the framework of the present thesis a system for the longitudinal phase modulation of the after-acceleration voltage in the cavity resonator of the DELTA storage ring is concipated, developed, constructed, taken in operation, and tested. Finally the results aimed hereby are presented and discussed.
Bruns, Peter C
2016-01-01
We give some estimates for the light-quark mass dependence of the pole position of the sigma ($f_{0}(500)$) resonance in the complex energy plane, with the help of a chiral Lagrangian for the resonance field and some input from hadronic models constrained by Chiral Perturbation Theory and elastic unitarity. We also speculate on the fate of the sigma resonance when the quark masses become unphysically large.
Harper, Jeremy; Malone, Stephen M; Bachman, Matthew D; Bernat, Edward M
2016-05-01
Recent work suggests that dissociable activity in theta and delta frequency bands underlies several common ERP components, including the no-go N2/P3 complex, which can better index separable functional processes than traditional time-domain measures. Reports have also demonstrated that neural activity can be affected by stimulus sequence context information (i.e., the number and type of preceding stimuli). Stemming from prior work demonstrating that theta and delta index separable processes during response inhibition, the current study assessed sequence context in a go/no-go paradigm in which the number of go stimuli preceding each no-go was selectively manipulated. Principal component analysis of time-frequency representations revealed differential modulation of evoked theta and delta related to sequence context, where delta increased robustly with additional preceding go stimuli, while theta did not. Findings are consistent with the view that theta indexes simpler initial salience-related processes, while delta indexes more varied and complex processes related to a variety of task parameters. © 2016 Society for Psychophysiological Research.
Omubo-Pepple V. B; Tamunobereton-ari I.; Briggs-Kamara M. A.
2013-01-01
This paper reports the investigation of some metrological parameters on the efficiency of photovoltaic module in some areas in the Niger Delta region of Nigeria. Results obtained show that efficiency of solar panel is directly proportional to solar flux and output current. Also, that increase in solar flux results to increase in output current of solar panel and enhance efficiency. It was also observed that relative humidity reduces output current and increases efficiency.
Carter, Pam
2010-12-01
When I was first introduced to the Six Sigma process, I resisted it with every ounce of energy I had. I continuously fabricated reasons so that I was unable to complete the training that my company required. When it came time for my performance review, I could not hide the truth from my manager; I had not completed the required training. It was then that I began my journey into the world of Six Sigma. Once I understood that a black belt and a green belt certification had nothing to do with karate, I felt much better.
Institute of Scientific and Technical Information of China (English)
刘宝宝; 李国刚; 杨骁; 凌朝东
2012-01-01
The establishment of behavioral-level system simulation platform can provide the accurate and overall time-domain simulations for Fractional-N Frequency Synthesizers design.It laid special stress on analyzing the 2/3 multi-modulus programmable divider and MASH Σ modulator.A new approach for calculating the parameters of loop filter was given.A set of Simulink circuit modes was designed.These modes structure an integrity Σ Fractional-N Frequency Synthesizers which can be used to predict and verify the circuit topologies in practice.%行为级仿真平台的建立,可以对小数频率综合器的设计提供快速全面的时域仿真.重点分析了2/3多模可编程分频器和MASH结构调制器电路,并给出了一种计算环路滤波器参数的新型工程方法.建立了的Simulink仿真模型,可用于检验电路结构的正确性.
Yi, Bitna; Sahn, James J.; Ardestani, Pooneh Memar; Evans, Andrew K.; Scott, Luisa; Chan, Jessica Z.; Iyer, Sangeetha; Crisp, Ashley; Zuniga, Gabriella; Pierce-Shimomura, Jonathan; Martin, Stephen F.; Shamloo, Mehrdad
2017-01-01
Accumulating evidence suggests that modulating the sigma 2 receptor (Sig2R) can provide beneficial effects for neurodegenerative diseases. Herein, we report the identification of a novel class of Sig2R binding ligands and their cellular and in vivo activity in experimental models of Alzheimer’s disease (AD). We report that SAS-0132 and DKR-1051, selective ligands of Sig2R, modulate intracellular Ca2+ levels in human SK-N-SH neuroblastoma cells. The Sig2R antagonists SAS-0132 and JVW-1009 are neuroprotective in a C. elegans model of amyloid precursor protein-mediated neurodegeneration. Since this neuroprotective effect is replicated by genetic knockdown and knockout of vem-1, the ortholog of progesterone receptor membrane component-1 (PGRMC1), it indicates that Sig2R ligands modulate a PGRMC1-related pathway. Last, we demonstrate that SAS-0132 improves cognitive performance both in the Thy-1 hAPPLond/Swe+ transgenic mouse model of AD and in healthy wild-type mice. These results demonstrate that Sig2R is a promising therapeutic target for neurocognitive disorders including AD. PMID:27926996
Operating principles of Notch-Delta-Jagged module of cell-cell communication
Jolly, Mohit Kumar; Boareto, Marcelo; Lu, Mingyang; Onuchic, Jose' N.; Clementi, Cecilia; Ben-Jacob, Eshel
2015-05-01
Notch pathway is an evolutionarily conserved cell-cell communication mechanism governing cell-fate during development and tumor progression. It is activated when Notch receptor of one cell binds to either of its ligand—Delta or Jagged—of another cell. Notch-Delta (ND) signaling forms a two-way switch, and two cells interacting via ND signaling adopt different fates—Sender (high ligand, low receptor) and Receiver (low ligand, high receptor). Notch-Delta-Jagged signaling (NDJ) behaves as a three-way switch and enables an additional fate—hybrid Sender/Receiver (S/R) (medium ligand, medium receptor). Here, by extending our framework of NDJ signaling for a two-cell system, we show that higher production rate of Jagged, but not that of Delta, expands the range of parameters for which both cells attain the hybrid S/R state. Conversely, glycosyltransferase Fringe and cis-inhibition reduces this range of conditions, and reduces the relative stability of the hybrid S/R state, thereby promoting cell-fate divergence and consequently lateral inhibition-based patterns. Lastly, soluble Jagged drives the cells to attain the hybrid S/R state, and soluble Delta drives them to be Receivers. We also discuss the critical role of hybrid S/R state in promoting cancer metastasis by enabling collective cell migration and expanding cancer stem cell (CSC) population.
Springs, Alison E B; Karmaus, Peer W F; Crawford, Robert B; Kaplan, Barbara L F; Kaminski, Norbert E
2008-12-01
The role of cannabinoid receptors, CB1 and CB2, in immune competence and modulation by Delta9-tetrahydrocannabinol (Delta9-THC) was investigated in CB1(-/-)/CB2(-/-) mice. Immunofluorescence analysis of splenic leukocytes showed no significant differences in the percentage of T cell subsets, B cells, or macrophages between wild-type and CB1(-/-)/CB2(-/-) mice. Lymphoproliferative control responses to PHA, phorbol ester plus ionomycin, or LPS and sensitivity to suppression by Delta9-THC showed no profound differences between the two genotypes, although some differences were observed in control baseline responses. Likewise, similar control responses and sensitivity to Delta9-THC were observed in mixed lymphocyte responses (MLR) and in IL-2 and IFN-gamma production in both genotypes. Conversely, humoral immune responses showed a markedly different profile of activity. Delta9-THC suppressed the in vivo T cell-dependent, anti-sheep RBC (anti-sRBC) IgM antibody-forming cell (AFC) response in wild-type but not in CB1(-/-)/CB2(-/-) mice, and the in vitro anti-sRBC IgM response in CB1(-/-)/CB2(-/-) splenocytes was too low to rigorously assess CB1/CB2 involvement in modulation by Delta9-THC. Conversely, comparable in vitro IgM AFC control responses to LPS and CD40 ligand (CD40L) activation were observed in the two genotypes. Interestingly, LPS-induced IgM responses were refractory to suppression by Delta9-THC, regardless of genotype, and CD40L-induced IgM responses were only suppressed by Delta9-THC in wild-type but not in CB1(-/-)/CB2(-/-) B cells. Collectively, we demonstrate differential involvement of CB1 and/or CB2 in immune modulation by Delta9-THC and in some control responses. Moreover, CB1/CB2 involvement was observed in humoral responses requiring CD40-initiated signaling for suppression by Delta9-THC.
∑∆ Modulator System-Level Considerations for Hearing-Aid Audio Class-D Output Stage Application
DEFF Research Database (Denmark)
Pracný, Peter; Bruun, Erik
2012-01-01
This paper deals with a system-level design of a digital sigma-delta (∑∆) modulator for hearing-aid audio Class D output stage application. The aim of this paper is to provide a thorough discussion on various possibilities and tradeoffs of ∑∆ modulator system-level design parameter combinations...
Realization of DVCCTA Based Versatile Modulator
Directory of Open Access Journals (Sweden)
Neeta Pandey
2014-01-01
Full Text Available A Differential Voltage Current Conveyor Transconductance Amplifier (DVCCTA based versatile modulator is proposed which can work as an amplitude modulator, frequency modulator, delta modulator, and sigma delta modulator. The modulator operational scheme uses pulse generator as a core and its output is used as carrier signal. A DVCCTA based pulse generator is proposed first and subsequently configured as different modulators. Compact realization is the key feature of the proposed circuit as it uses two DVCCTA; a grounded resistor and a grounded capacitor hence are appropriate for IC realization. The functionality of the proposed circuit is verified through SPICE simulations using TSMC 0.25 μm CMOS process model parameters. The performance parameters such as power dissipation and noise for various modulator schemes are also obtained.
Hoyle, C H; Kamm, M A; Burnstock, G; Lennard-Jones, J E
1990-01-01
1. A sucrose-gap technique was used to investigate the neuromodulatory actions of enkephalins on non-adrenergic, non-cholinergic inhibitory junction potentials (IJPs) in the circular muscle of the human large intestine. 2. The native enkephalins, [Leu5]enkephalin (LENK) and [Met5]enkephalin (MENK) caused a concentration-dependent reduction in amplitude of IJPs without a significant effect on the smooth muscle membrane. 3. The actions of LENK and MENK were mimicked by the delta-selective opioid receptor agonists [D-Pen2, D-Pen5]enkephalin (DPDPE) and [D-Ala2, D-Leu5]enkephalin (DADLE). 4. The actions of LENK, MENK and DPDPE were antagonized to similar extents by the delta-selective opioid receptor antagonist ICI 174,864. 5. The mu-selective opioid receptor agonist [D-Ala2, Me Phe, Gly-ol5]enkephalin was approximately 100-fold less potent than any of the native or synthetic enkephalins at reducing the amplitude of the IJP. Dynorphin A and beta-endorphin both had very weak activity. 6. Responses to all of the agonists were inhibited by naloxone. The degree of antagonism of DPDPE or DADLE by naloxone (1 microM) was the same as that of LENK or MENK. 7. Neither MENK nor LENK affected hyperpolarization of the smooth muscle membrane induced by ATP or 5-hydroxytryptamine. Vasoactive intestinal polypeptide (1 pM-1 microM) did not produce any observable responses and this lack of reactivity was not affected by the enkephalins. 8. It is concluded that in the circular muscle of the human colon, LENK and MENK can act on prejunctional delta-opioid receptors to produce inhibition of non-adrenergic, non-cholinergic inhibitory neuromuscular transmission. Possible physiological significance of this prejunctional receptor is discussed. PMID:1966052
Depke, Maren; Burian, Marc; Schäfer, Tina; Bröker, Barbara M; Ohlsen, Knut; Völker, Uwe
2012-01-01
Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Kidney tissues of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant were analyzed by transcriptome profiling to monitor the host response, and additionally expression of selected S. aureus genes was monitored by RT-qPCR. Direct transcript analysis by RT-qPCR revealed significant SigB activity in all mice infected with the wild-type strain, but not in its isogenic sigB mutant (p<0.0001). Despite a clear-cut difference in the SigB-dependent transcription pattern of virulence genes (clfA, aur, and hla), the host reaction to infection (either wild type or sigB mutant) was almost identical. Despite its significant activity in vivo, loss of SigB did neither have an effect on the outcome of infection nor on murine kidney gene expression pattern. Thus, these data support the role of SigB as virulence modulator rather than being a virulence determinant by itself.
Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats
Directory of Open Access Journals (Sweden)
Victoria Andino-Pavlovsky
2017-05-01
Full Text Available Dopamine release and phase-amplitude cross-frequency coupling (CFC have independently been implicated in prefrontal cortex (PFC functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP recorded from the medial PFC (mPFC of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC.
用精益六西格玛方法完善某T/R组件生产工艺%T/R Module Production Process Optimization Using Lean 6 Sigma Method
Institute of Scientific and Technical Information of China (English)
汤俊; 傅涛
2013-01-01
本文介绍了精益生产和六西格玛的基本含义及特点，通过精益生产和六西格玛管理的对比分析，指出了实施精益六西格玛的必要性和可行性。针对我所某T/R组件生产工艺中存在的实际问题，成立精益六西格玛绿带项目组，根据精益六西格玛的五个基本步骤，充分运用适宜的常用方法和工具，改进、完善了该产品T/R组件生产工艺，大大缩短了调试时间，取得了较好的经济效益，达到了预期的目标。%The concept and characteristic of lean production and 6 sigma method is introduced in the paper. Lean production and 6 sigma management is contrastively analyzed, which is indicated that it is necessary and feasible for introducing lean 6 sigma into mass production. Aiming at actual problems in T/R module production process, 6 sigma management group was setup, and based on 6 sigma five basic analysis approach, methods and tools were adequately used in the study. T/R module production process was improved and optimized, which decreased tuning time. Great economic benefit is gained, and expectant target is achieved.
Positive modulation of delta-subunit containing GABA_{A} receptors in mouse neurons
DEFF Research Database (Denmark)
Vardya, Irina; Hoestgaard-Jensen, Kirsten; Nieto-Gonzalez, Jose Luis;
2012-01-01
δ-subunit containing extrasynaptic GABA(A) receptors are potential targets for modifying neuronal activity in a range of brain disorders. With the aim of gaining more insight in synaptic and extrasynaptic inhibition, we used a new positive modulator, AA29504, of δ-subunit containing GABA(A) recep...
Role of melatonin in modulation of oxidative stress induced by delta-
Directory of Open Access Journals (Sweden)
El-Sawi, MR, Badawy, ME and El-Gharieb, NM.
2007-09-01
Full Text Available Backgrounds: Delta-aminolevulinic acid (ALA is a heme precursor that accumulates in acute intermittent porphyria (AIP due to enzymatic deficiencies in the heme biosynthetic pathway, its accumulation has been associated with several symptoms because it works as an endogenous source of reactive oxygen species, which can exert oxidative damage to cell structures. The present work was designed to examine the ability of melatonin, a well known antioxidant and a free radical scavenger secreted from the pineal gland, to revert ALA-promoted damage in brain, liver and kidney of rats. Results: The present data demonstrated that chronically ALA-treated rats (40 mg / kg body wt day after day for 14 days exhibited very highly significant increases in malondialdehyde (MDA and protein carbonyl (PC whereas the level of glutathione (GSH was significantly diminished in the tissue homogenates of all tested organs (brain, kidney & liver. Among antioxidant enzymes, superoxide dismutase (SOD, catalase (CAT, glutathione reductase (GSH-Rd, glutathione-S-transferase (GST activities were significantly diminished by ALA treatment. Intraperitoneal injection of melatonin (10 mg / kg body weight, every day for 14 consecutive days significantly ameliorated all the tested parameters. Melatonin moderately increased SOD, CAT, GSH-Rd and GST activities, thereby counteracting the oxidative stress induced by ALA. Nevertheless, exogenous ALA caused a strong net rise in MDA and PC and a significant decrease in GSH when given together with ALA, melatonin antagonized these effects and largely protected the integrity of tissue structures. From the present data, the protection of melatonin against ALA oxidative stress is obviously, so it is well recommended to use melatonin in patients suffering from symptoms related to ALA accumulation
SIGMA Final Report: Volume V, Part 4. The Design of SIGMA.
1982-05-01
sender , subject, date/time stamp, etc.--so that the message behind it is identifiable. It also specifies the nature of transmission, whether a message is...number, the new mail and alert counts, the load aerage, and the time of day. is generated and sent to the Driver. - Ithe user queue is not empty. the...deletes folders from the SIGMA folder database (DELETE-FOLDER). " It updates folders with delta file information (DELTA-UPDATE). * It creates inboxes
Directory of Open Access Journals (Sweden)
Prof. Ph.D. Sorin-George Toma
2008-12-01
Full Text Available Over the past decades, several business improvement methods were launched, includingthe one known as Six Sigma. The Six Sigma implies the application of scientific principles to business processesand allows companies to obtain better, faster and cheaper products and services. Motorola was thefirst company that introduced and implemented Six Sigma in its business processes in the 1980s.
Mobility modulation in inverted delta doped coupled double quantum well structure
Sahoo, N.; Sahu, T.
2016-10-01
We have studied the modulation of electron mobility μ as a function of the electric field perpendicular to the interface plane Fp in a GaAs/AlGaAs double quantum well structure near the resonance of subband states. The functional dependence of μ on Fp exhibits a minimum near the anticrossing of subband states leading to an oscillatory behavior of μ. We show that the oscillatory enhancement of μ becomes more pronounced with increase in the difference between the doping concentrations in the side barriers. The oscillation of μ also increases by varying the widths of the two wells through shifting of the position of the middle barrier. It is interesting to show that the oscillation of μ is always larger when there is doping in barrier towards the substrate side compared to that of the surface side due to the difference in the influence of the interface roughness scattering potential. Further, broadening of the central barrier width increases the peaks of the oscillation of μ mostly due to the changes in the ionized impurity scattering potential. Our results can be utilized for the performance enhancement of quantum well field effect transistor devices.
Mobility modulation in inverted delta doped coupled double quantum well structure
Energy Technology Data Exchange (ETDEWEB)
Sahoo, N. [Department of Electronic Science, Berhampur University, 760007, Odisha (India); Sahu, T., E-mail: tsahu_bu@rediffmail.com [Department of Electronics and Communication Engineering, National Institute of Science and Technology, Palur Hills, Berhampur 761008, Odisha (India)
2016-10-01
We have studied the modulation of electron mobility μ as a function of the electric field perpendicular to the interface plane F{sub p} in a GaAs/AlGaAs double quantum well structure near the resonance of subband states. The functional dependence of μ on F{sub p} exhibits a minimum near the anticrossing of subband states leading to an oscillatory behavior of μ. We show that the oscillatory enhancement of μ becomes more pronounced with increase in the difference between the doping concentrations in the side barriers. The oscillation of μ also increases by varying the widths of the two wells through shifting of the position of the middle barrier. It is interesting to show that the oscillation of μ is always larger when there is doping in barrier towards the substrate side compared to that of the surface side due to the difference in the influence of the interface roughness scattering potential. Further, broadening of the central barrier width increases the peaks of the oscillation of μ mostly due to the changes in the ionized impurity scattering potential. Our results can be utilized for the performance enhancement of quantum well field effect transistor devices.
Stellar delta matter with delta-meson coupling constants constrained by QCD sum rule
Energy Technology Data Exchange (ETDEWEB)
Silva, Antonio Ferreira da [Secretaria de Educacao, Cultura e Desportos do Estado de Roraima (SECD/RR), Boa Vista, RR (Brazil); Oliveira, Jose Carlos Teixeira de [Universidade Federal de Roraima (UFRR), Boa Vista, RR (Brazil); Rodrigues, Hilario [Centro Federal de Educacao Tecnologica (CEFET-RJ), Rio de Janeiro, RJ (Brazil); Duarte, Sergio Barbosa [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Chiapparini, Marcelo [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil)
2010-07-01
The considerable presence of delta-resonances (30% of baryonic population) in the dense phase of relativistic heavy ion collisions leads to a great interest in the study of the delta matter formation in the deep interior of compact stars. In the present work we determine the equation of state and the population of baryons and leptons and discuss the effects of the baryon-meson coupling constants to the formation of delta matter in the stellar medium. We use the non-linear Walecka model consisting of the octet of baryons of spin 1=2 (n, p, {Lambda}{sup 0}, {Sigma}{sup -}, {Sigma}{sup 0}, {Sigma}{sup +}, {Xi}{sup -}, {Xi}{sup 0}) and baryonic resonances of spin 3=2, represented by the delta resonances ({Delta}{sup -}, ({Delta}{sup 0}, ({Delta}{sup +}, ({Delta}{sup ++}) and {Omega}{sup -}, in the baryonic sector. In the leptonic sector we consider the electrons and muons. The coupling constants between the hyperons {Lambda}, {Sigma}, and {Xi} and the mesons {omega} and {rho} are fixed by using SU(6) symmetry, while the hyperons-{sigma} coupling constants are constrained by the consistence of the hypernuclear potential in the nuclear matter with hypernuclear data. In addition, we use the finite density QCD sum rule to determine the possible values of delta-meson coupling constants. (author)
A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator
DEFF Research Database (Denmark)
Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre
The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub...
Institute of Scientific and Technical Information of China (English)
Feng Hui(冯晖); Lin Zhenghui
2004-01-01
Cascaded sigma-delta (MASH) modulators for higher order oversampled analog-to-digital conversion rely on precise matching of contributions from different quantizers to cancel lower order quantization noise from intermediate delta-sigma stages. This paper studies the effect of analog imperfections in the implementation, such as finite gain of the amplifiers and capacitor ratio mismatch, and presents an adaptive algorithm and implementation architectures for digital correction of such analog imperfections. Behavioral simulations on 1-1-1 oversampled converters demonstrate over 10dB improvements in signal-to-noise and over 20 dB improvements in dynamic range performance.
Energy Technology Data Exchange (ETDEWEB)
Tang, Jun [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China); Department of Physiology, Third Military Medical University, Chongqing 400038 (China); Song, Min; Wang, Yanyan [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China); Fan, Xiaotang [Department of Histology and Embryology, Third Military Medical University, Chongqing 400038 (China); Xu, Haiwei, E-mail: haiweixu2001@yahoo.com.cn [Department of Physiology, Third Military Medical University, Chongqing 400038 (China); Bai, Yun, E-mail: baiyungene@gmail.com [Department of Medical Genetics, Third Military Medical University, Chongqing 400038 (China)
2009-07-31
In addition to the subventricular zone, the dentate gyrus of the hippocampus is one of the few brain regions in which neurogenesis continues into adulthood. Perturbation of neurogenesis can alter hippocampal function, and previous studies have shown that neurogenesis is dysregulated in Alzheimer disease (AD) brain. Bone morphogenetic protein-4 (BMP4) and its antagonist Noggin have been shown to play important roles both in embryonic development and in the adult nervous system, and may regulate hippocampal neurogenesis. Previous data indicated that increased expression of BMP4 mRNA within the dentate gyrus might contribute to decreased hippocampal cell proliferation in the APP{sub swe}/PS1{sub {Delta}E9} mouse AD model. However, it is not known whether the BMP antagonist Noggin contributes to the regulation of neurogenesis. We therefore studied the relative expression levels and localization of BMP4 and its antagonist Noggin in the dentate gyrus and whether these correlated with changes in neurogenesis in 6-12 mo old APP{sub swe}/PS1{sub {Delta}E9} transgenic mice. Bromodeoxyuridine (BrdU) was used to label proliferative cells. We report that decreased neurogenesis in the APP/PS1 transgenic mice was accompanied by increased expression of BMP4 and decreased expression of Noggin at both the mRNA and protein levels; statistical analysis showed that the number of proliferative cells at different ages correlated positively with Noggin expression and negatively with BMP4 expression. Intraventricular administration of a chimeric Noggin/Fc protein was used to block the action of endogenous BMP4; this resulted in a significant increase in the number of BrdU-labeled cells in dentate gyrus subgranular zone and hilus in APP/PS1 mice. These results suggest that BMP4 and Noggin co-modulate neurogenesis.
Sigma-1 Receptor in Motoneuron Disease.
Mancuso, Renzo; Navarro, Xavier
2017-01-01
Amyotrophic Lateral Sclerosis (ALS ) is a neurodegenerative disease affecting spinal cord and brain motoneurons , leading to paralysis and early death. Multiple etiopathogenic mechanisms appear to contribute in the development of ALS , including glutamate excitotoxicity, oxidative stress , protein misfolding, mitochondrial defects, impaired axonal transport, inflammation and glial cell alterations. The Sigma-1 receptor is highly expressed in motoneurons of the spinal cord, particularly enriched in the endoplasmic reticulum (ER) at postsynaptic cisternae of cholinergic C-terminals. Several evidences point to participation of Sigma-1R alterations in motoneuron degeneration. Thus, mutations of the transmembrane domain of the Sigma-1R have been described in familial ALS cases. Interestingly, Sigma-1R KO mice display muscle weakness and motoneuron loss. On the other hand, Sigma-1R agonists promote neuroprotection and neurite elongation through activation of protein kinase C on motoneurons in vitro and in vivo after ventral root avulsion. Remarkably, treatment of SOD1 mice, the most usual animal model of ALS , with Sigma-1R agonists resulted in significantly enhanced motoneuron function and preservation, and increased animal survival. Sigma-1R activation also reduced microglial reactivity and increased the glial expression of neurotrophic factors. Two main interconnected mechanisms seem to underlie the effects of Sigma-1R manipulation on motoneurons: modulation of neuronal excitability and regulation of calcium homeostasis. In addition, Sigma-1R also contributes to regulating protein degradation, and reducing oxidative stress. Therefore, the multi-functional nature of the Sigma-1R represents an attractive target for treating aspects of ALS and other motoneuron diseases .
Sigma photoproduction in the resonance region
Janssen, S; Debruyne, D; Van Cauteren, T
2002-01-01
A study of p(gamma,K)Sigma processes in an isobar model at tree level is reported. By comparing model calculations to the published SAPHIR data, we explore the possible role of different isospin I=1/2 (N*) and I=3/2 (Delta*) resonances in the reaction dynamics. In our analysis, the inclusion of the ``missing'' D_{13}(1895) resonance does only slightly improve the global description of the Sigma photoproduction data. More convincing signals for the presence of such a ``missing'' resonance emerged in the analysis of the isospin related p(gamma,K+)Lambda reaction. Various implementations of the nonresonant part of the Sigma photoproduction amplitude are presented. The sensitivity of the computed observables and extracted resonance parameters to the uncertainties inherent to the treatment of the nonresonant (background) diagrams are discussed.
Gulcin Daglioglu; Inal, Tamer C.; Kiymet Aksoy
2009-01-01
Sigma (σ) refers to Standard Deviation which is a measure of variation in statistics. Methodology of Six Sigma is a management philosophy that is based on the theory that parameters can be cotrolled. Six Sigma applications follow the process of identifying and defining defects, analyzing the defects using various measures, suggesting improvements and having metrics or controls in place to achieve the goals of the business. The error rate is defined as the number of error in a million. An...
Directory of Open Access Journals (Sweden)
Gulcin Daglioglu
2009-04-01
Full Text Available Sigma (σ refers to Standard Deviation which is a measure of variation in statistics. Methodology of Six Sigma is a management philosophy that is based on the theory that parameters can be cotrolled. Six Sigma applications follow the process of identifying and defining defects, analyzing the defects using various measures, suggesting improvements and having metrics or controls in place to achieve the goals of the business. The error rate is defined as the number of error in a million. An increase in Sigma means decrease in the number of error, and lower values of Sigma correspond to higher number of error. The Six Sigma philosophy aims to bring about improvements in processes that have zero error. The Six Sigma approach is to implement methodologies that aim at reaching world standard quality which is 6 Sigma or more. The Six Sigma methodology used in clinical laboratories appears to be a quality management tool involving statistical calculations, process parameter based, and reports about the process performance. [Archives Medical Review Journal 2009; 18(2.000: 132-139
Six Sigma software development
Tayntor, Christine B
2002-01-01
Since Six Sigma has had marked success in improving quality in other settings, and since the quality of software remains poor, it seems a natural evolution to apply the concepts and tools of Six Sigma to system development and the IT department. Until now however, there were no books available that applied these concepts to the system development process. Six Sigma Software Development fills this void and illustrates how Six Sigma concepts can be applied to all aspects of the evolving system development process. It includes the traditional waterfall model and in the support of legacy systems,
Stamhuis, Eize; Lengkeek, W
2015-01-01
A support structure (2) is installed in or near a water (50). The support structure is holding a deltalike-wing (3) under an angle of incidence relative to an incoming flow (54), caused by at least a prevailing current in the water, thus generating a vortex (77). The action of the vortex is
Plastid sigma factors: Their individual functions and regulation in transcription.
Chi, Wei; He, Baoye; Mao, Juan; Jiang, Jingjing; Zhang, Lixin
2015-09-01
Sigma factors are the predominant factors involved in transcription regulation in bacteria. These factors can recruit the core RNA polymerase to promoters with specific DNA sequences and initiate gene transcription. The plastids of higher plants originating from an ancestral cyanobacterial endosymbiont also contain sigma factors that are encoded by a small family of nuclear genes. Although all plastid sigma factors contain sequences conserved in bacterial sigma factors, a considerable number of distinct traits have been acquired during evolution. The present review summarises recent advances concerning the regulation of the structure, function and activity of plastid sigma factors since their discovery nearly 40 years ago. We highlight the specialised roles and overlapping redundant functions of plastid sigma factors according to their promoter selectivity. We also focus on the mechanisms that modulate the activity of sigma factors to optimise plastid function in response to developmental cues and environmental signals. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
Shiba, Yasuo; Ueda, Masayoshi
2013-02-01
We studied the December sigma-Virginids from the TV meteor observation network database in Japan (the "SonotaCo Network"). The December sigma-Virginids are a minor annual meteor shower that has a broad peak around December 20 and about 40 days active duration. The visual maximum zenithal hourly rate (ZHR) is estimated at 1.5.
Generalized Poisson sigma models
Batalin, I; Batalin, Igor; Marnelius, Robert
2001-01-01
A general master action in terms of superfields is given which generates generalized Poisson sigma models by means of a natural ghost number prescription. The simplest representation is the sigma model considered by Cattaneo and Felder. For Dirac brackets considerably more general models are generated.
LeMahieu, Paul G.; Nordstrum, Lee E.; Cudney, Elizabeth A.
2017-01-01
Purpose: This paper is one of seven in this volume that aims to elaborate different approaches to quality improvement in education. It delineates a methodology called Six Sigma. Design/methodology/approach: The paper presents the origins, theoretical foundations, core principles and a case study demonstrating an application of Six Sigma in a…
LeMahieu, Paul G.; Nordstrum, Lee E.; Cudney, Elizabeth A.
2017-01-01
Purpose: This paper is one of seven in this volume that aims to elaborate different approaches to quality improvement in education. It delineates a methodology called Six Sigma. Design/methodology/approach: The paper presents the origins, theoretical foundations, core principles and a case study demonstrating an application of Six Sigma in a…
Membrillo-Hernández, J; Kim, S O; Cook, G M; Poole, R K
1997-01-01
We report the first example of a gene, hmp, encoding a soluble flavohemoglobin in Escherichia coli K-12, which is up-regulated by paraquat in a SoxRS-independent manner. Unlike what is found for other paraquat-inducible genes, high concentrations of paraquat (200 microM) were required to increase the level of hmp expression, and maximal induction was observed only after 20 min of exposure to paraquat. Neither a mutation in soxS nor one in soxR prevented the paraquat-dependent increase in phi(hmp-lacZ) expression, but either mutant allele delayed full expression of phi(hmp-lacZ) activity after paraquat addition. Induction of hmp by paraquat was demonstrated in aerobically grown cultures during exponential growth and the stationary phase, thus revealing two Sox-independent regulatory mechanisms. Induction of hmp by paraquat in the stationary phase was dependent on the global regulator of stationary-phase gene expression, RpoS (sigma S). However, a mutation in rpoS did not prevent an increase in hmp expression by paraquat in exponentially growing cells. Induction of sigma S in the exponential phase by heat shock also induced phi(hmp-lacZ) expression in the presence of paraquat, supporting the role of sigma S in one of the regulatory mechanisms. Mutations in oxyR or rob, known regulators of several stress promoters in E. coli, had no effect on the induction of hmp by paraquat. Other known superoxide-generating agents (plumbagin, menadione, and phenazine methosulfate) were not effective in inducing hmp expression. PMID:9150210
Lin, Ping-Yuan; Lee, Jeng-Woei; Liao, Ming-Huei; Hsu, Hsue-Yin; Chiu, Shu-Jun; Liu, Hung-Jen; Shih, Wen-Ling
2009-03-15
ARV S1133 infection caused apoptosis in vivo and in vitro; however, the intracellular signaling pathways have not been fully delineated. We have previously demonstrated that ARV S1133 activates proapoptotic signaling from Src to p53, and further investigated how ARV S1133 modulates p53. We found that ARV S1133 forms syncytia and induces apoptosis in CEF, DF1 and Vero cells with different kinetics. Enhancement of p53 phosphorylation and DNA-binding capacity to bax and bad promoters was found in this study to increase bax and bad expression in ARV S1133-infected cells. ARV S1133 activates PKC delta and p38 and JNK/SAPK pathways, and inhibition of Ras, p38, JNK/SAPK and PKC delta works efficiently against apoptosis. Suppression of p38, JNK/SAPK and PKC delta selectively abolished ARV S1133-mediated p53 phosphorylation; moreover, inhibition of Src did not affect ARV S1133-induced p38 and JNK/SAPK activation, whereas blocking of Ras resulted in a reduction in the activities of p38 and JNK/SAPK.
Narrow Sigma -hypernuclear states
Gal, A
1980-01-01
It is shown that the spin-isospin dependence of low-energy Sigma N to Lambda N conversion leads to substantial quenching of nuclear-matter estimates of the widths of some Sigma -hypernuclear states produced in (K/sup -/, pi ) reactions, to a level below 10 MeV. The estimated widths compare favorably with those of the Sigma -hypernuclear peaks recently observed at CERN for /sup 7/Li, /sup 9/Be, and /sup 12/C. Tentative quantum number assignments are suggested for these states. (10 refs).
Cesbron, Sophie; Paulin, Jean-Pierre; Tharaud, Michel; Barny, Marie-Anne; Brisset, Marie-Noëlle
2006-04-01
In this work we present evidence of an opposite regulation in the phytopathogenic bacteria Erwinia amylovora between the virulence-associated Type III secretion system (TTSS) and the flagellar system. Using loss-of-function mutants we show that motility enhanced the virulence of wild-type bacteria relative to a nonmotile mutant when sprayed on apple seedlings with unwounded leaves. Then we demonstrated through analyses of motility, flagellin export and visualization of flagellar filament that HrpL, the positive key regulator of the TTSS, also down-regulates the flagellar system. Such a dual regulation mediated by an alternative sigma factor of the TTSS appears to be a level of regulation between virulence and motility not yet described among Proteobacteria.
Energy Technology Data Exchange (ETDEWEB)
Bagger, J.A.
1984-09-01
We begin to construct the most general supersymmetric Lagrangians in one, two and four dimensions. We find that the matter couplings have a natural interpretation in the language of the nonlinear sigma model.
A topological sigma model of biKaehler geometry
Energy Technology Data Exchange (ETDEWEB)
Zucchini, Roberto [Dipartimento di Fisica, Universita degli Studi di Bologna, V. Irnerio 46, I-40126 Bologna (Italy); I.N.F.N., sezione di Bologna (Italy)
2006-01-15
BiKaehler geometry is characterized by a riemannian metric g{sub ab} and two covariantly constant generally non commuting complex structures K{sub {+-}}{sup a}{sub b}, with respect to which g{sub ab} is hermitean. It is a particular case of the bihermitean geometry of Gates, Hull and Roceck, the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. We present a sigma model for biKaehler geometry that is topological in the following sense: i) the action is invariant under a fermionic symmetry {delta}; ii) {delta} is nilpotent on shell; iii) the action is {delta}-exact on shell up to a topological term; iv) the resulting field theory depends only on a subset of the target space geometrical data. The biKaehler sigma model is obtainable by gauge fixing the Hitchin model with generalized Kaehler target space. It further contains the customary A topological sigma model as a particular case. However, it is not seemingly related to the (2,2) supersymmetric biKaehler sigma model by twisting in general.
A topological sigma model of biKaehler geometry
Zucchini, R
2006-01-01
BiKaehler geometry is characterized by a Riemannian metric g_{ab} and two covariantly constant generally non commuting complex structures K_+^a_b, K_-^a_b, with respect to which g_{ab} is Hermitian. It is a particular case of the biHermitian geometry of Gates, Hull and Roceck, the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. We present a sigma model for biKaehler geometry that is topological in the following sense: i) the action is invariant under a fermionic symmetry delta; ii) delta is nilpotent on shell; iii) the action is delta--exact on shell up to a topological term; iv) the resulting field theory depends only on a subset of the target space geometrical data. The biKaehler sigma model is obtainable by gauge fixing the Hitchin model with generalized Kaehler target space. It further contains the customary A topological sigma model as a particular case. However, it is not seemingly related to the (2,2) supersymmetric biKaehler sigma model by twisting in gener...
Sigma factors in Pseudomonas aeruginosa.
Potvin, Eric; Sanschagrin, François; Levesque, Roger C
2008-01-01
In Pseudomonas aeruginosa, as in most bacterial species, the expression of genes is tightly controlled by a repertoire of transcriptional regulators, particularly the so-called sigma (sigma) factors. The basic understanding of these proteins in bacteria has initially been described in Escherichia coli where seven sigma factors are involved in core RNA polymerase interactions and promoter recognition. Now, 7 years have passed since the completion of the first genome sequence of the opportunistic pathogen P. aeruginosa. Information from the genome of P. aeruginosa PAO1 identified 550 transcriptional regulators and 24 putative sigma factors. Of the 24 sigma, 19 were of extracytoplasmic function (ECF). Here, basic knowledge of sigma and ECF proteins was reviewed with particular emphasis on their role in P. aeruginosa global gene regulation. Summarized data are obtained from in silico analysis of P. aeruginosasigma and ECF including rpoD (sigma(70)), RpoH (sigma(32)), RpoF (FliA or sigma(28)), RpoS (sigma(S) or sigma(38)), RpoN (NtrA, sigma(54) or sigma(N)), ECF including AlgU (RpoE or sigma(22)), PvdS, SigX and a collection of uncharacterized sigma ECF, some of which are implicated in iron transport. Coupled to systems biology, identification and functional genomics analysis of P. aeruginosasigma and ECF are expected to provide new means to prevent infection, new targets for antimicrobial therapy, as well as new insights into the infection process.
Yajima, Y; Narita, M; Takahashi-Nakano, Y; Misawa, M; Nagase, H; Mizoguchi, H; Tseng, L F; Suzuki, T
2000-04-17
The present study investigated the effects of micro-, delta- and kappa-opioid receptor agonists on seizures produced by blockade of gamma-aminobutyric acid (GABA)-mediated synaptic transmission in the mouse. The selective GABA(A) receptor antagonist bicuculline (1.25-3 mg/kg) given subcutaneously caused dose-dependent clonic-tonic convulsions. These convulsions were potentiated by the prototypic mu-opioid receptor agonist morphine given subcutaneously 20 min prior to a subconvulsive dose of bicuculline. The potentiation by morphine was completely reversed by pretreatment intraventricularly with the selective mu-opioid receptor antagonist beta-funaltrexamine (0.5 microgram/mouse). Pretreatment intraventricularly with the selective delta-opioid receptor agonists 2-methyl-4aalpha-(3-hydroxyphenyl)-1,2,3,4,4a,5,12, 12abeta-octahydro-quinolino[2,3,3-g]isoquinoline ((-)TAN-67) or [D-Pen(2,5)]-enkephalin (DPDPE) showed a dose-dependent increase in the incidence of convulsions. Pretreatment with naltrindole (2 mg/kg, s.c.), a selective delta-opioid receptor antagonist, abolished the enhancement of the bicuculline-induced convulsions by DPDPE. In contrast, pretreatment with the selective kappa-opioid receptor agonist U-50,488H (0.6-80 mg/kg, subcutaneously or 25-100 microgram/mouse, intraventricularly) produced a dose-dependent suppression of the bicuculline-induced convulsions. The inhibitory effect of U-50,488H was completely blocked by pretreatment subcutaneously with nor-binaltorphimine (5 mg/kg), a selective kappa-opioid receptor antagonist. This study demonstrates that activation of both mu- and delta-opioid receptors increases the incidence of convulsions produced by blockade of GABA-mediated synaptic transmission, while stimulation of kappa-opioid receptors has an anticonvulsive effect.
Behler, Matthias
2007-01-01
The radiative decay of a hyperon into a light hyperon and a photon allows to study the structure of the electroweak interaction of hadrons. For this purpose, the decay asymmetry is an appropriate observable. It describes the distribution of the daughter hyperon with respect to the polarization $vec{P}$ of the mother hyperon by $dN / d cos(Theta) propto 1 + alpha |vec{P}| cos(Theta)$, where $Theta$ is the angle between $vec{P}$ and the momentum of the daughter hyperon. The radiative decay $Xi^0 to Lambda gamma$ is of particular interest since all calculations at quark level predict a positive decay asymmetry whereas two existing measurements result in a negative value of $alpha_{Lambda gamma} = -0.73 pm 0.17$. The goal of the analysis presented here was to verify these results and to improve the accuracy of the decay asymmetry measurement. In addition, the decay asymmetry of the similar decay $Xi^0 to Sigma^0 gamma$ was measured, and the well-known decay $Xi^0 to Lambda pi^0$ was used to test the analysis str...
$sigma(600)$ and background in $pipi$ scattering
Kaloshin, A E; Vall, A N
2003-01-01
We suggest a simple analytical description of the S-wave isoscalar $pipi$ amplitude, which corresponds to a joint dressing of the bare resonance and background contributions. The amplitude describes well the experimental data on the $delta^0_0$ phase shift in the energy region below 900 MeV and has two poles in the $Re s > 0$ half-plane. Besides the well-known pole of $sigma(600)$-meson with $Re s sim m_{pi}^2$, there exists a more distant pole with $Re s sim 0.6 GeV^2$. Our analysis indicates for the dynamical origin of the $sigma(600)$ pole, while the second pole should be associated with lowest $qbar{q}$ state.
Charged current weak electroproduction of $\\Delta$ resonance
Alvarez-Ruso, L; Vacas, M J V
1998-01-01
We study the weak production of $\\Delta$ (i.e. $e^{-} + p \\to \\Delta^{0}+ energy range corresponding to the Mainz and TJNAF electron accelerators. The differential cross sections $\\sigma(\\theta)$ are found to be of the order of $ 10^{-39}$ cm$^2$/sr, over a range of angles which increases with energy. The possibility of observing these reactions with the high luminosities available at these accelerators, and studying the weak N-$\\Delta$ transition form factors through these reactions is discussed. The production cross section of N$^*(1440)$ in the kinematic region of $\\Delta$ production is also estimated and found to be small.
Energy Technology Data Exchange (ETDEWEB)
Hsieh, Chih-Chun [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China); Wu, Weite, E-mail: wwu@dragon.nchu.edu.t [Department of Materials Science and Engineering, National Chung Hsing University, 250 Kuo-Kuang Rd., Taichung 402, Taiwan (China)
2010-09-17
Research highlights: This article concentrates the phase transformation in {delta} {yields} {sigma} in dissimilar stainless steels using the Vitek equation and thermodynamics simulation during the multi-pass welding. The phase transformation in {delta} {yields} {sigma} is very important to the properties of stainless steel composites. In this study, the diffusion behavior of Cr, Ni and Si in the {delta}, {sigma}, and {gamma} phases were discussed using the DSC analysis and diffusion equation calculation. This method has a novelty for discussing the phase transformation in {delta} {yields} {sigma} in the dissimilar stainless steel. We hope that we can give a scientific contribution for the phase transformation of the dissimilar stainless steels during the multi-pass welding. - Abstract: This study performed a precipitation examination of the {sigma} phase using the Vitek diffusion equation and thermodynamic simulation in dissimilar stainless steels during multi-pass welding. The results of the experiment demonstrate that the diffusion rates (D{sub Cr}{sup {delta}} and D{sub Ni}{sup {delta}}) of Cr and Ni are higher in {delta}-ferrite than (D{sub Cr}{sup {gamma}} and D{sub Ni}{sup {gamma}}) in the {gamma} phase and that they facilitate the precipitation of {sigma} phase in the third pass fusion zone. When the diffusion activation energy of Cr in {delta}-ferrite is equal to that of Ni in {delta}-ferrite (Q{sub dCr}{sup {delta}}=Q{sub dNi}{sup {delta}}), phase transformation of the {delta} {yields} {sigma} can be occurred.
Energy Technology Data Exchange (ETDEWEB)
Mitev, Vladimir
2010-08-15
The purpose of this thesis is to deepen our understanding of the fundamental properties and defining features of non-linear sigma models on superspaces. We begin by presenting the major concepts that we have used in our investigation, namely Lie superalgebras and supergroups, non-linear sigma models and two dimensional conformal field theory. We then exhibit a method, called cohomological reduction, that makes use of the target space supersymmetry of non-linear sigma models to compute certain correlation functions. We then show how the target space supersymmetry of Ricci flat Lie supergroups simplifies the perturbation theory of suitable deformed Wess-Zumino-Witten models, making it possible to compute boundary conformal weights to all orders. This is then applied to the OSP (2S+2 vertical stroke 2S) Gross-Neveu Model, leading to a dual description in terms of the sigma model on the supersphere S{sup 2S+1} {sup vertical} {sup stroke} {sup 2S}. With this results in mind, we then turn to the similar, yet more intricate, theory of the non-linear sigma model on the complex projective superspaces CP{sup N-1} {sup vertical} {sup stroke} {sup N}. The cohomological reduction allows us to compute several important quantities non-perturbatively with the help of the system of symplectic fermions. Combining this with partial perturbative results for the whole theory, together with numerical computations, we propose a conjecture for the exact evolution of boundary conformal weights for symmetry preserving boundary conditions. (orig.)
Directory of Open Access Journals (Sweden)
Glen P Carter
2011-10-01
Full Text Available Nosocomial infections are increasingly being recognised as a major patient safety issue. The modern hospital environment and associated health care practices have provided a niche for the rapid evolution of microbial pathogens that are well adapted to surviving and proliferating in this setting, after which they can infect susceptible patients. This is clearly the case for bacterial pathogens such as Methicillin Resistant Staphylococcus aureus (MRSA and Vancomycin Resistant Enterococcus (VRE species, both of which have acquired resistance to antimicrobial agents as well as enhanced survival and virulence properties that present serious therapeutic dilemmas for treating physicians. It has recently become apparent that the spore-forming bacterium Clostridium difficile also falls within this category. Since 2000, there has been a striking increase in C. difficile nosocomial infections worldwide, predominantly due to the emergence of epidemic or hypervirulent isolates that appear to possess extended antibiotic resistance and virulence properties. Various hypotheses have been proposed for the emergence of these strains, and for their persistence and increased virulence, but supportive experimental data are lacking. Here we describe a genetic approach using isogenic strains to identify a factor linked to the development of hypervirulence in C. difficile. This study provides evidence that a naturally occurring mutation in a negative regulator of toxin production, the anti-sigma factor TcdC, is an important factor in the development of hypervirulence in epidemic C. difficile isolates, presumably because the mutation leads to significantly increased toxin production, a contentious hypothesis until now. These results have important implications for C. difficile pathogenesis and virulence since they suggest that strains carrying a similar mutation have the inherent potential to develop a hypervirulent phenotype.
Energy Technology Data Exchange (ETDEWEB)
Babinski, Adam; Witczak, P.; Twardowski, A.; Baranowski, J. M.
2001-06-18
Electroluminescence (EL) from a forward-biased Schottky barrier diode on modulation Si {delta}-doped pseudomorphic GaAs/InGaAs/AlGaAs heterostructure with high mobility electron gas is investigated in this work. It has been found that the EL from the InGaAs quantum well can be observed at temperatures up to 90 K. The EL line shape depends on the current density, which reflects the filling of the InGaAs channel with electrons. The total integrated EL intensity depends linearly on the current density. We propose that hole diffusion from an inversion layer at the Schottky barrier is responsible for the observed optical recombination with electrons in the InGaAs quantum well. {copyright} 2001 American Institute of Physics.
Mlynczak, Martin G.
1993-01-01
The rate at which molecular oxygen absorbs radiation in the O2(X3Sigma-g - b1Sigma-g) transition is calculated using a line-by-line radiative transfer model. This rate is critical to the determination of the population of the O2(b1Sigma-g) state required for studies of the O2(b1Sigma-g - X3Sigma-g) dayglow, the O2(a1Delta-g - X3Sigma-g) dayglow, and possibly the rates of oxidation of H2 and N2O. Previous evaluations of this rate (which is sometimes called the g-factor) have significantly overestimated its value. The rate is tabulated as a function of altitude, pressure, and solar zenith angle.
A model for sigma factor competition in bacterial cells.
Mauri, Marco; Klumpp, Stefan
2014-10-01
Sigma factors control global switches of the genetic expression program in bacteria. Different sigma factors compete for binding to a limited pool of RNA polymerase (RNAP) core enzymes, providing a mechanism for cross-talk between genes or gene classes via the sharing of expression machinery. To analyze the contribution of sigma factor competition to global changes in gene expression, we develop a theoretical model that describes binding between sigma factors and core RNAP, transcription, non-specific binding to DNA and the modulation of the availability of the molecular components. The model is validated by comparison with in vitro competition experiments, with which excellent agreement is found. Transcription is affected via the modulation of the concentrations of the different types of holoenzymes, so saturated promoters are only weakly affected by sigma factor competition. However, in case of overlapping promoters or promoters recognized by two types of sigma factors, we find that even saturated promoters are strongly affected. Active transcription effectively lowers the affinity between the sigma factor driving it and the core RNAP, resulting in complex cross-talk effects. Sigma factor competition is not strongly affected by non-specific binding of core RNAPs, sigma factors and holoenzymes to DNA. Finally, we analyze the role of increased core RNAP availability upon the shut-down of ribosomal RNA transcription during the stringent response. We find that passive up-regulation of alternative sigma-dependent transcription is not only possible, but also displays hypersensitivity based on the sigma factor competition. Our theoretical analysis thus provides support for a significant role of passive control during that global switch of the gene expression program.
Orient, O. J.; Chutjian, A.; Murad, E.
1995-01-01
Optical emissions in single-collision, beam-beam reactions of fast (3-22 eV translational energy) O(P-3) atoms with C2H2 have been measured in the wavelength range 300-850 nm. Two features were observed, one with a peak wavelength at 431 nm, corresponding to the CH A (sup 2)Delta yields X (sup 2)Pi(sub r) transition, and a second weaker emission in the range 380-400 nm corresponding to the B (sup 2)Sigma(sup -) yields X (sup 2)Pi(sub r) transition. Both the A yields X and B yields X emissions were fit to a synthetic spectrum of CH(A) at a vibrational temperature T(sub v) of 10,000 K (0.86 eV) and a rotational temperature T(r) of approximately 5000 K (0.43 eV); and CH(B) to T(sub v) = 2500 K (0.22 eV) and T(sub r) = 1000 K (0.09 eV). The energy threshold for the A yields X emission was measured to be 7.3 +/- 0.4 eV (lab) or 4.5 +/- 0.2 eV (c.m.). This agrees with the energy threshold of 7.36 eV (lab) for the reaction O(P-3) + C2H2 yields CH(A) + HCO.
Inclusive $\\Sigma^{+}$ and $\\Sigma^{0}$ Production in Hadronic Z Decays
Acciarri, M; Adriani, O; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Ambrosi, G; Anderhub, H; Andreev, V P; Angelescu, T; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, L; Balandras, A; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Barone, L; Bartalini, P; Basile, M; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Bhattacharya, S; Biasini, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brigljevic, V; Brochu, F; Buffini, A; Buijs, A; Burger, J D; Burger, W J; Cai, X D; Campanelli, M; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Castellini, G; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada-Canales, M; Cesaroni, F; Chamizo-Llatas, M; Chang, Y H; Chaturvedi, U K; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Civinini, C; Clare, I; Clare, R; Coignet, G; Colijn, A P; Colino, N; Costantini, S; Cotorobai, F; Cozzoni, B; de la Cruz, B; Csilling, Akos; Cucciarelli, S; Dai, T S; van Dalen, J A; D'Alessandro, R; De Asmundis, R; Déglon, P L; Degré, A; Deiters, K; Della Volpe, D; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Van Dierendonck, D N; Di Lodovico, F; Dionisi, C; Dittmar, Michael; Dominguez, A; Doria, A; Dova, M T; Duchesneau, D; Dufournaud, D; Duinker, P; Durán, I; El-Mamouni, H; Engler, A; Eppling, F J; Erné, F C; Extermann, Pierre; Fabre, M; Faccini, R; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Ferroni, F; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisk, I; Forconi, G; Fredj, L; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gau, S S; Gentile, S; Gheordanescu, N; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hasan, A; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hidas, P; Hirschfelder, J; Hofer, H; Holzner, G; Hoorani, H; Hou, S R; Hu, Y; Iashvili, I; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Khan, R A; Kaur, M; Kienzle-Focacci, M N; Kim, D; Kim, J K; Kirkby, Jasper; Kiss, D; Kittel, E W; Klimentov, A; König, A C; Kopp, A; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Lassila-Perini, K M; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Lee, H J; Le Goff, J M; Leiste, R; Leonardi, E; Levchenko, P M; Li Chuan; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luckey, D; Lugnier, L; Luminari, L; Lustermann, W; Ma Wen Gan; Maity, M; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Marchesini, P A; Marian, G; Martin, J P; Marzano, F; Massaro, G G G; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Von der Mey, M; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Molnár, P; Monteleoni, B; Moulik, T; Muanza, G S; Muheim, F; Muijs, A J M; Musy, M; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Organtini, G; Oulianov, A; Palomares, C; Pandoulas, D; Paoletti, S; Paolucci, P; Paramatti, R; Park, H K; Park, I H; Pascale, G; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pieri, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Postema, H; Pothier, J; Produit, N; Prokofev, D; Prokofiev, D O; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Raspereza, A V; Raven, G; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Van Rhee, T; Riemann, S; Riles, K; Robohm, A; Rodin, J; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Rubio, Juan Antonio; Ruschmeier, D; Rykaczewski, H; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Sarakinos, M E; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Sciarrino, D; Seganti, A; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Smith, B; Spillantini, P; Steuer, M; Stickland, D P; Stone, A; Stone, H; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Suter, H; Swain, J D; Szillási, Z; Sztaricskai, T; Tang, X W; Tauscher, Ludwig; Taylor, L; Tellili, B; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Uchida, Y; Ulbricht, J; Valente, E; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Vorvolakos, A; Wadhwa, M; Wallraff, W; Wang, M; Wang, X L; Wang, Z M; Weber, A; Weber, M; Wienemann, P; Wilkens, H; Wu, S X; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Ye, J B; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhu, G Y; Zhu, R Y; Zichichi, A; Zilizi, G; Zöller, M
2000-01-01
We report on measurements of the inclusive production rate of $\\Sigma^+$ and $\\Sigma^0$ baryons in hadronic Z decays collected with the L3 detector at LEP. The $\\Sigma^+$ baryons are detected through the decay $\\Sigma^+ \\rightarrow {\\rm p} \\pi^0$, while the $\\Sigma^0$ baryons are detected via the decay mode $\\Sigma^0 \\rightarrow \\Lambda \\gamma$. The average numbers of $\\Sigma^+$ and $\\Sigma^0$ per hadronic Z decay are measured to be: \\begin{eqnarray*} \\left + \\left & = & 0.114 \\pm 0.011_{\\mbox{\\it \\small stat}} \\pm 0.009_{\\mbox{\\it \\small syst}} \\\\ \\left + \\left & = & 0.095 \\pm 0.015_{\\mbox{\\it \\small stat}} \\pm 0.013_{\\mbox{\\it \\small syst}} \\ \\mbox{.} \\end{eqnarray*} These rates are found to be higher than the predictions from Monte Carlo hadronization models and analytical parameterizations of strange baryon production.
VLSI Potentiostat Array With Oversampling Gain Modulation for Wide-Range Neurotransmitter Sensing.
Stanacevic, M; Murari, K; Rege, A; Cauwenberghs, G; Thakor, N V
2007-03-01
A 16-channel current-measuring very large-scale integration (VLSI) sensor array system for highly sensitive electrochemical detection of electroactive neurotransmiters like dopamine and nitric-oxide is presented. Each channel embeds a current integrating potentiostat within a switched-capacitor first-order single-bit delta-sigma modulator implementing an incremental analog-to-digital converter. The duty-cycle modulation of current feedback in the delta-sigma loop together with variable oversampling ratio provide a programmable digital range selection of the input current spanning over six orders of magnitude from picoamperes to microamperes. The array offers 100-fA input current sensitivity at 3.4-muW power consumption per channel. The operation of the 3 mm times3 mm chip fabricated in 0.5-mum CMOS technology is demonstrated with real-time multichannel acquisition of neurotransmitter concentration.
Six Sigma and Implementations of Six Sigma in Finance Sector
Gokhan Senol; Adem Anbar
2010-01-01
Quality is a one of the critical factors for achieving competitive advantage. Six sigma approach is a business strategy which usage has increased gradually in last years for quality improvement initiative. Although six sigma established by a manufacturing firm and it has been successfully implemented in many manufacturing firms, service firms have began to use six sigma for reducing cost, enhanced quality of service, increasing customer satisfaction and profitability. In this paper, six sigma...
Direct observations of sigma phase growth and dissolution in 2205 duplex stainless steel
Energy Technology Data Exchange (ETDEWEB)
Palmer, T.A.; Elmer, J.W.; Babu, S.S.; Specht, E.D. (LLNL); (ORNL)
2007-10-10
The formation and growth of sigma ({sigma}) phase in a 2205 duplex stainless steel is monitored during an 850 C isothermal heat treatment using an in situ synchrotron x-ray diffraction technique. At this temperature, {sigma} phase is first observed within approximately 40 seconds of the start of the isothermal heat treatment and grows rapidly over the course of the 3600 second heat treatment to a volume fraction of approximately 13%. A simultaneous increase in the austenite ({gamma}) volume fraction and a decrease in the ferrite ({delta}) volume fraction are observed. The {sigma} phase formed at this temperature is rapidly dissolved within approximately 200 seconds when the temperature is increased to 1000 C. Accompanying this rapid dissolution of the {sigma} phase, the {delta} and {gamma} volume fractions both approach the balanced (50/50) level observed in the as-received material.
Geometry of Membrane Sigma Models
Vysoky, Jan
2015-01-01
String theory still remains one of the promising candidates for a unification of the theory of gravity and quantum field theory. One of its essential parts is relativistic description of moving multi-dimensional objects called membranes (or p-branes) in a curved spacetime. On the classical field theory level, they are described by an action functional extremalising the volume of a manifold swept by a propagating membrane. This and related field theories are collectively called membrane sigma models. Differential geometry is an important mathematical tool in the study of string theory. It turns out that string and membrane backgrounds can be conveniently described using objects defined on a direct sum of tangent and cotangent bundles of the spacetime manifold. Mathematical field studying such object is called generalized geometry. Its integral part is the theory of Leibniz algebroids, vector bundles with a Leibniz algebra bracket on its module of smooth sections. Special cases of Leibniz algebroids are better ...
Supersymmetric Sigma Model Geometry
Ulf Lindström
2012-01-01
This is a review of how sigma models formulated in Superspace have become important tools for understanding geometry. Topics included are: The (hyper)k\\"ahler reduction; projective superspace; the generalized Legendre construction; generalized K\\"ahler geometry and constructions of hyperk\\"ahler metrics on Hermitean symmetric spaces.
Liem Ferryanto
2007-01-01
This article provides a step by step process of executing analytical or computer based Design for Six Sigma using a Sliding Door project as an example. It comprises of identification of Voice Of the Customer (VOC), transformation of VOC to what it is called Critical To Quality characteristics (CTQs), modeling of system transfers function, optimal and robust solutions, and tolerance design approach
Supersymmetric Sigma Model geometry
Lindström, Ulf
2012-01-01
This is a review of how sigma models formulated in Superspace have become important tools for understanding geometry. Topics included are: The (hyper)k\\"ahler reduction; projective superspace; the generalized Legendre construction; generalized K\\"ahler geometry and constructions of hyperk\\"ahler metrics on Hermitean symmetric spaces.
Six Sigma and Implementations of Six Sigma in Finance Sector
Directory of Open Access Journals (Sweden)
Gokhan Senol
2010-04-01
Full Text Available Quality is a one of the critical factors for achieving competitive advantage. Six sigma approach is a business strategy which usage has increased gradually in last years for quality improvement initiative. Although six sigma established by a manufacturing firm and it has been successfully implemented in many manufacturing firms, service firms have began to use six sigma for reducing cost, enhanced quality of service, increasing customer satisfaction and profitability. In this paper, six sigma was examined in a view of finance sector and applications of six sigma within the finance sector were evaluated.
Does \\Sigma -\\Sigma -\\alpha Form a Quasi-Bound State?
Htun Oo, H; Kamada, H; Glöckle, W
2004-01-01
We have investigated the possible existence of a quasi-bound state for the \\Sigma -\\Sigma -\\alpha system in the framework of Faddeev calculations. We are particularly interested in the state of total iso-spin T=2, since for an inert \\alpha particle there is no strong conversion to \\Xi -N-\\alpha or \\Lambda -\\Lambda -\\alpha possible. A \\Sigma -\\alpha optical potential based on Nijmegen model D and original \\Sigma -\\Sigma interactions of the series of Nijmegen potentials NSC97 as well a simulated Gaussian type versions thereof are used. Our investigation of the \\Sigma -\\Sigma -\\alpha system leads to a quasi bound state where, depending on the potential parameters, the energy ranges between -1.4 and -2.4 MeV and the level width is about 0.2MeV.
Bajc, B.; Blin, A. H.; Hiller, B.; Nemes, M. C.; Rosina, M.
1994-01-01
We calculate the momentum dependence of three particle vertices $\\sigma \\gamma \\gamma$, $\\sigma \\rho \\gamma$ and $\\sigma \\rho \\rho$ in the context of a Nambu Jona Lasinio type model. We show how they influence the processes $\\gamma \\gamma \\rightarrow \\sigma \\rightarrow \\pi \\pi$, $\\rho \\rightarrow \\gamma \\sigma$ and $\\gamma \\gamma \\rightarrow \\rho \\rho$ and how chiral symmetry shadows the presence of the $\\sigma$.
Directory of Open Access Journals (Sweden)
Liem Ferryanto
2007-01-01
Full Text Available This article provides a step by step process of executing analytical or computer based Design for Six Sigma using a Sliding Door project as an example. It comprises of identification of Voice Of the Customer (VOC, transformation of VOC to what it is called Critical To Quality characteristics (CTQs, modeling of system transfers function, optimal and robust solutions, and tolerance design approach
Zajícová, Hana
2010-01-01
Bachelor thesis deals with the desription of the statistical foundations and individual steps of Six Sigma, which are descibed by the DMAIC model. The thesis focuses on statistical process control and control charts. The main goal is to evaluate the possible use of control charts for attributes, namely the control chart for fraction nonconforming or p-diagram and to describe its properties expressed by the operating characteristic (OC). The influence of the sample size on the OC curve is exam...
Gravitating $\\sigma$ Model Solitons
Kim, Yoonbai; Moon, Sei-Hoon
1998-01-01
We study axially symmetric static solitons of O(3) nonlinear $\\sigma$ model coupled to (2+1)-dimensional anti-de Sitter gravity. The obtained solutions are not self-dual under static metric. The usual regular topological lump solution cannot form a black hole even though the scale of symmetry breaking is increased. There exist nontopological solitons of half integral winding in a given model, and the corresponding spacetimes involve charged Ba$\\tilde n$ados-Teitelboim-Zanelli black holes with...
Sodhi, ManMohan S; Sodhi, Navdeep S
2005-05-01
Many companies are now good at managing costs and wringing out manufacturing efficiencies. The TQM movement and the disciplines of Six Sigma have seen to that. But the discipline so often brought to the cost side of the business equation is found far less commonly on the revenue side. The authors describe how a global manufacturer of industrial equipment, which they call Acme Incorporated, recently applied Six Sigma to one major revenue related activity--the price-setting process. It seemed to Acme's executives that pricing closely resembled many manufacturing processes. So, with the help of a Six Sigma black belt from manufacturing, a manager from Acme's pricing division recruited a team to carry out the five Six Sigma steps: Define what constitutes a defect. At Acme, a defect was an item sold at an unauthorized price. Gather data and prepare it for analysis. That involved mapping out the existing pricing-agreement process. Analyze the data. The team identified the ways in which people failed to carry out or assert effective control at each stage. Recommend modifications to the existing process. The team sought to decrease the number of unapproved prices without creating an onerous approval apparatus. Create controls. This step enabled Acme to sustain and extend the improvements in its pricing procedures. As a result of the changes, Acme earned dollar 6 million in additional revenue on one product line alone in the six months following implementation--money that went straight to the bottom line. At the same time, the company removed much of the organizational friction that had long bedeviled its pricing process. Other companies can benefit from Acme's experience as they look for ways to exercise price control without alienating customers.
Purification and activities of the Rhodobacter capsulatus RpoN (sigma N) protein.
Cannon, W; Missailidis, S; Austin, S; Moore, M; Drake, A; Buck, M
1996-07-01
The rpoN-encoded sigma factors (sigma N) are a distinct class of bacterial sigma factors, with no obvious homology to the major sigma 70 class. The sigma N-containing RNA polymerase holoenzyme functions in enhancer-dependent transcription to allow expression of positively controlled genes. We have purified the Rhodobacter capsulatus sigma N protein, which is distinctive in lacking an acidic region implicated in the melting of promoter DNA by the Escherichia coll sigma N holoenzyme, and may represent a minor subclass of sigma N proteins. Assays of promoter recognition and holoenzyme formation and function showed that the purified R. capsulatus sigma N protein is distinct in activity compared to the enteric proteins, but retains the broad functions described for these proteins. As first described for the Klebsiella pneumoniae protein, promoter recognition in the absence of core RNA polymerase was detected, but contact of certain promoter bases by the R. capsulatus sigma N protein and its response to core RNA polymerase was clearly different from that determined for the K. pneumoniae and E. coli proteins. Results are discussed in the context of a requirement to modulate the activity of the DNA-binding surfaces of sigma N to regulate sigma N function. Circular dichroism was used to evaluate the structure of the R. capsulatus protein and revealed differences in the tertiary signals as compared to the K. pneumoniae protein, some of which are attributable to the DNA-binding domain of sigma N.
Charfi, Iness; Nagi, Karim; Mnie-Filali, Ouissame; Thibault, Dominic; Balboni, Gianfranco; Schiller, Peter W; Trudeau, Louis-Eric; Pineyro, Graciela
2014-04-01
Signaling bias refers to G protein-coupled receptor ligand ability to preferentially activate one type of signal over another. Bias to evoke signaling as opposed to sequestration has been proposed as a predictor of opioid ligand potential for generating tolerance. Here we measured whether delta opioid receptor agonists preferentially inhibited cyclase activity over internalization in HEK cells. Efficacy (τ) and affinity (KA) values were estimated from functional data and bias was calculated from efficiency coefficients (log τ/KA). This approach better represented the data as compared to alternative methods that estimate bias exclusively from τ values. Log (τ/KA) coefficients indicated that SNC-80 and UFP-512 promoted cyclase inhibition more efficiently than DOR internalization as compared to DPDPE (bias factor for SNC-80: 50 and for UFP-512: 132). Molecular determinants of internalization were different in HEK293 cells and neurons with βarrs contributing to internalization in both cell types, while PKC and GRK2 activities were only involved in neurons. Rank orders of ligand ability to engage different internalization mechanisms in neurons were compared to rank order of E max values for cyclase assays in HEK cells. Comparison revealed a significant reversal in rank order for cyclase E max values and βarr-dependent internalization in neurons, indicating that these responses were ligand-specific. Despite this evidence, and because kinases involved in internalization were not the same across cellular backgrounds, it is not possible to assert if the magnitude and nature of bias revealed by rank orders of maximal responses is the same as the one measured in HEK cells.
Gravitating $\\sigma$ Model Solitons
Kim, Y; Kim, Yoonbai; Moon, Sei-Hoon
1998-01-01
We study axially symmetric static solitons of O(3) nonlinear $\\sigma$ model coupled to (2+1)-dimensional anti-de Sitter gravity. The obtained solutions are not self-dual under static metric. The usual regular topological lump solution cannot form a black hole even though the scale of symmetry breaking is increased. There exist nontopological solitons of half integral winding in a given model, and the corresponding spacetimes involve charged Ba$\\tilde n$ados-Teitelboim-Zanelli black holes without non-Abelian scalar hair.
Hernández, Antonio García; Monteiro, Mário J P F G; Suárez, Juan Carlos; Reese, Daniel R; Pascual-Granado, Javier; Garrido, Rafael
2015-01-01
Delta Scuti ($\\delta$ Sct) stars are intermediate-mass pulsators, whose intrinsic oscillations have been studied for decades. However, modelling their pulsations remains a real theoretical challenge, thereby even hampering the precise determination of global stellar parameters. In this work, we used space photometry observations of eclipsing binaries with a $\\delta$ Sct component to obtain reliable physical parameters and oscillation frequencies. Using that information, we derived an observational scaling relation between the stellar mean density and a frequency pattern in the oscillation spectrum. This pattern is analogous to the solar-like large separation but in the low order regime. We also show that this relation is independent of the rotation rate. These findings open the possibility of accurately characterizing this type of pulsator and validate the frequency pattern as a new observable for $\\delta$ Sct stars.
Observation of the Heavy Baryons Sigma b and Sigma b*.
Aaltonen, T; Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; DaRonco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Tesarek, R J; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S
2007-11-16
We report an observation of new bottom baryons produced in pp collisions at the Tevatron. Using 1.1 fb(-1) of data collected by the CDF II detector, we observe four Lambda b 0 pi+/- resonances in the fully reconstructed decay mode Lambda b 0-->Lambda c + pi-, where Lambda c+-->pK* pi+. We interpret these states as the Sigma b(*)+/- baryons and measure the following masses: m Sigma b+=5807.8 -2.2 +2.0(stat.)+/-1.7(syst.) MeV/c2, m Sigma b- =5815.2+/-1.0(stat.)+/-1.7(syst.) MeV/c2, and m(Sigma b*)-m(Sigma b)=21.2-1.9 +2.0(stat.)-0.3+0.4(syst.) MeV/c2.
The sigma receptor as a ligand-regulated auxiliary potassium channel subunit.
Aydar, Ebru; Palmer, Christopher P; Klyachko, Vitaly A; Jackson, Meyer B
2002-04-25
The sigma receptor is a novel protein that mediates the modulation of ion channels by psychotropic drugs through a unique transduction mechanism depending neither on G proteins nor protein phosphorylation. The present study investigated sigma receptor signal transduction by reconstituting responses in Xenopus oocytes. Sigma receptors modulated voltage-gated K+ channels (Kv1.4 or Kv1.5) in different ways in the presence and absence of ligands. Association between Kv1.4 channels and sigma receptors was demonstrated by coimmunoprecipitation. These results indicate a novel mechanism of signal transduction dependent on protein-protein interactions. Domain accessibility experiments suggested a structure for the sigma receptor with two cytoplasmic termini and two membrane-spanning segments. The ligand-independent effects on channels suggest that sigma receptors serve as auxiliary subunits to voltage-gated K+ channels with distinct functional interactions, depending on the presence or absence of ligand.
Energy Technology Data Exchange (ETDEWEB)
Doucleff, Michaeleen; Malak, Lawrence T.; Pelton, Jeffrey G.; Wemmer, David E.
2005-11-01
The ''{delta}'' subunit of prokaryotic RNA-polymerase allows gene-specific transcription initiation. Two {sigma} families have been identified, {sigma}{sup 70} and {sigma}{sup 54}, which use distinct mechanisms to initiate transcription and share no detectable sequence homology. Although the {sigma}{sup 70}-type factors have been well characterized structurally by x-ray crystallography, no high-resolution structural information is available for the {sigma}{sup 54}-type factors. Here we present the NMR derived structure of the C-terminal domain of {sigma}{sup 54} from Aquifex aeolicus. This domain (Thr323 to Gly389), which contains the highly conserved RpoN box sequence, consists of a poorly structured N-terminal tail followed by a three-helix bundle, which is surprisingly similar to domains of the {sigma}{sup 70}-type proteins. Residues of the RpoN box, which have previously been shown to be critical for DNA binding, form the second helix of an unpredicted helix-turn-helix motif. This structure's homology with other DNA binding proteins, combined with previous biochemical data, suggest how the C-terminal domain of {sigma}{sup 54} binds to DNA.
Rudolph, H.; McKoy, V.; Dixit, S. N.; Huo, W. M.
1988-01-01
Results are presented for the rotationally resolved photoelectron spectra resulting from a (2 + 1) one-color resonant enhanced multiphoton ionization (REMPI) of NO via the rotationally clean S21(11.5) and mixed S11(15.5) + R21(15.5) branches of the 0-0 transition in the D-X band. The calculations were done in the fixed-nuclei frozen core approximation. The resulting photoionization spectra, convoluted with a Lorentzian detection function, agree qualitatively with experimental results of Viswanathan et al. (1986) and support their conclusion that the nonspherical nature of the molecular potential creates a substantial l-mixing in the continuum, which in turn leads to the intense Delta N = 0 peak. The rather strong photoelectron energy dependence of the rotational branching ratios of the D 2Sigma(+) S21(11.5) line was investigated and compared to the weak energy dependence of the A 2Sigma(+) R22(21.5) line.
Das, Sudhakar; Mohapatra, Meryleen; Nayak, Rasmita K.; Panda, Ajit K.; Sahu, Trinath
2017-03-01
We study the enhancement of electron mobility μ in barrier delta-doped GaAs/AlGaAs quantum-well-based modulation-doped field-effect transistor (MODFET) structures. We asymmetrically vary the doping concentrations N d1 and N d2 in the barriers on the substrate and surface sides, respectively, to obtain a nonlinear enhancement of μ as a function of the well width w through multi-subband effects. We show that an increase in doping concentration increases the surface electron density N s, which in turn enhances μ. Interchanging N d1 and N d2 leads to no change in N s but rather, an enhancement of μ as a function of w for N d2 > N d1 owing to asymmetric variation of subband wave functions, thereby implying a higher channel conductivity in a surface-doped structure than in an inverted doped structure. By keeping (N d1 + N d2) unchanged, the conductivity of a single-channel MODFET, N d1 (N d2) ≠ 0 and N d2 (N d1) = 0, can be enhanced by considering a MODFET based on an asymmetrically doped (N d1 ≠ N d2 ≠ 0) quantum well structure. We show that the highest N s and μ product for these structures occurs almost before the onset of the occupation of the second subband. Our analysis of the effect of asymmetric doping profiles on channel conductivity can be utilized for the performance improvement of MODFET-like devices.
Institute of Scientific and Technical Information of China (English)
刘素娟; 张特; 陈建新
2011-01-01
A novel design method for hardware-efficient digital interpolation filter applied to stereo audio SigmaDelta Digital-to-Analog Converter ( ∑ - △ DAC) is proposed in this paper. The method proclaims a new structure of multiplexing the interpolation filter by the left and right channel. The reorder technique is presented to keep the two channels being completely synchronization after multiplexing. The design is fabricated on TSMC 0.18μm 1.8 V/3.3 V 1P5M CMOS process. The measurement results show that the DAC achieves 106 dB SNR over the 20 kHz audio band. The digital part of chip occupies only 0.198 mm2 and dissipates only 0.65 mW power. This design method benefits low chip area and power consumption and leaves much more design margin to the analog part of the ∑ - △ DAC, which provides important significance in mixed-signal system design.%该文提出了一种新型双声道音频∑-△数模转换器(DAC)小面积插值滤波器设计方法.该方法采用左右两个声道复用一个插值滤波器的新型结构,并利用存储器实现第1级半带滤波器,从而降低芯片的实现面积.提出重新排序方法,保证复用后两个声道的同步.设计在TSMC 0.18μm 1.8 V/3.3 V 1P5M CMOS工艺上实现,测试信噪比为106dB,数字部分芯片的面积仅为0.198 mm2,功耗为0.65 mW.这种设计方法降低了∑-△DAC系统中数字部分的面积和功耗,给模拟部分留有较大的设计裕量,这对模数混合系统的设计具有重要的意义.
Stability predictions for high-order ΣΔ modulators based on quasilinear modeling
DEFF Research Database (Denmark)
Risbo, Lars
1994-01-01
This paper introduces a novel interpretation of the instability mechanisms in high-order one-bit Sigma-Delta modulators. Furthermore, it is demonstrated how the maximum stable amplitude range can be predicted very well. The results are obtained using an extension of the well known quasilinear mod...... modeling of the one-bit quantizer. The theoretical results are verified by numerical simulations of a number of realistic 4th order modulators designed by means of standard filter design tools. The results are useful for automated design and optimization of loop filters...
Herder, J.L.; Van der Wijk, V.
2010-01-01
The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le
Herder, J.L.; Van der Wijk, V.
2010-01-01
The invention relates to a delta robot comprising a stationary base (2) and a movable platform (3) that is connected to the base with three chains of links (4,5,6), and comprising a balancing system incorporating at least one pantograph (7) for balancing the robot's center of mass, wherein the at le
Energy Technology Data Exchange (ETDEWEB)
Candu, Constantin [Institut fuer Theoretische Physik, Zuerich (Switzerland); Mitev, Vladimir [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Mathematik; Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group
2013-08-15
We compute the complete 1-loop spectrum of anomalous dimensions for the bulk fields of non-linear sigma models on symmetric coset (super)spaces G/H, both with and without world-sheet supersymmetry. In addition, we provide two new methods for the construction of partition functions in the infinite radius limit and demonstrate their efficiency in the case of (super)sphere sigma models. Our results apply to a large number of target spaces including superspheres and superprojective spaces such as the N=2 sigma model on CP{sup 3} {sup vertical} {sup stroke} {sup 4}.
Six sigma for revenue retrieval.
Plonien, Cynthia
2013-01-01
Deficiencies in revenue retrieval due to failures in obtaining charges have contributed to a negative bottom line for numerous hospitals. Improving documentation practices through a Six Sigma process improvement initiative can minimize opportunities for errors through reviews and instill structure for compliance and consistency. Commitment to the Six Sigma principles with continuous monitoring of outcomes and constant communication of results to departments, management, and payers is a strong approach to reducing the financial impact of denials on an organization's revenues and expenses. Using Six Sigma tools can help improve the organization's financial performance not only for today, but also for health care's uncertain future.
N, Vivekananthamoorthy; S, ankar
2011-01-01
Методология Lean Six Sigma, которая идеально подходит для проектов, направленных на уменьшение объема потерь, длительности бизнес-циклов, их вариаций, а также для увеличения качества продукта, может служить основой для улучшения бизнес-процессов.
Baryonic resonances close to the Kbar-N threshold: the case of Sigma(1385)^+ in pp collisions
Agakishiev, G; Belver, D; Belyaev, A V; Blanco, A; Boehmer, M; Boyard, J L; Cabanelas, P; Castro, E; Chen, J C; Chernenko, S; Christ, T; Destefanis, M; Dohrmann, F; Dybczak, A; Epple, E; Eberl, T; Fabbietti, L; Fateev, O V; Finocchiaro, P; Fonte, P; Friese, J; Froehlich, I; Galatyuk, T; Garzon, J A; Gernhaeuser, R; Gilardi, C; Golubeva, M; Gonzalez-Diaz, D; Guber, F; Gumberidze, M; Heinz, T; Hennino, T; Holzmann, R; Iori, I; Ivashkin, A; Jurkovic, M; Kaempfer, B; Kanaki, K; Karavicheva, T; Koenig, I; Koenig, W; Kolb, B W; Kotte, R; Krasa, A; Krizek, F; Kruecken, R; Kuc, H; Kuehn, W; Kugler, A; Kurepin, A; Lalik, R; Lang, S; Lange, J S; Lapidus, K; Liu, T; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Markert, J; Metag, V; Michalska, B; Michel, J; Moriniere, E; Mousa, J; Muentz, C; Naumann, L; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Pietraszko, J; Przygoda, W; Ramstein, B; Reshetin, A; Rustamov, A; Sadovsky, A; Salabura, P; Schmah, A; Schwab, E; Siebenson, J; Sobolev, Yu G; Spataro, S; Spruck, B; Stroebele, H; Stroth, J; Sturm, C; Tarantola, A; Teilab, K; Tlusty, P; Traxler, M; Trebacz, R; Tsertos, H; Wagner, V; Weber, M; Wendisch, C; Wuestenfeld, J; Yurevich, S; Zanevsky, Y V
2011-01-01
We present results of an exclusive measurement of the first excited state of the Sigma hyperon, Sigma(1385)^+, produced in p+p -> Sigma^+ + K^+ + n at 3.5 GeV beam energy. The extracted data allow to study in detail the invariant mass distribution of the Sigma(1385)^+. The mass distribution is well described by a relativistic Breit-Wigner function with a maximum at m_0 = 1383.2 +- 0.9 MeV/c^2 and a width of 40.2 +- 2.1 MeV/c^2. The exclusive production cross-section comes out to be 22.27 +- 0.89 +- 1.56 +3.07 -2.10 mu b. Angular distributions of the Sigma(1385)^+ in different reference frames are found to be compatible with the hypothesis that 33 % of Sigma(1385)^+ result from the decay of an intermediate Delta^{++} resonance.
Nguyen, Linda; Lucke-Wold, Brandon P; Mookerjee, Shona; Kaushal, Nidhi; Matsumoto, Rae R
2017-01-01
Sigma-1 receptors are molecular chaperones that may act as pathological mediators and targets for novel therapeutic applications in neurodegenerative diseases. Accumulating evidence indicates that sigma-1 ligands can either directly or indirectly modulate multiple neurodegenerative processes, including excitotoxicity, calcium dysregulation, mitochondrial and endoplasmic reticulum dysfunction, inflammation, and astrogliosis. In addition, sigma-1 ligands may act as disease-modifying agents in the treatment for central nervous system (CNS) diseases by promoting the activity of neurotrophic factors and neural plasticity. Here, we summarize their neuroprotective and neurorestorative effects in different animal models of acute brain injury and chronic neurodegenerative diseases, and highlight their potential role in mitigating disease. Notably, current data suggest that sigma-1 receptor dysfunction worsens disease progression, whereas enhancement amplifies pre-existing functional mechanisms of neuroprotection and/or restoration to slow disease progression. Collectively, the data support a model of the sigma-1 receptor as an amplifier of intracellular signaling, and suggest future clinical applications of sigma-1 ligands as part of multi-therapy approaches to treat neurodegenerative diseases.
Running Head: Implementing Six Sigma Efforts
Lindsay, Jamie Eleaitia Mae
2005-01-01
Six Sigma is an organization wide program that provides common set of goals, language, and methodology for improving the overall quality of the processes within the organization (Davis & Heineke 2004). Six Sigma main concern is for the customer. What will the customers want? Need? Six Sigma has a model that helps Sigma get implemented DMAIC model…
A 0.2V, 7.5 μW, 20 kHz ΣΔ modulator with 69 dB SNR in 90 nm CMOS
DEFF Research Database (Denmark)
Wismar, Ulrik Sørensen; Wisland, D; Andreani, Pietro
2007-01-01
This paper presents a frequency-to-digital SigmaDelta modulator designed in a digital 90nm CMOS process, operating with a supply voltage of 0.2 V. For a 7.5 muW power consumption, the SNR is 68.9 dB and the SNDR is 60.3 dB over a 20Hz-20kHz bandwidth. This work shows that the SNR/SNDR performance...
Longitudinal spin asymmetries and $\\Delta G$ at COMPASS
Le Goff, Jean-Marc
2008-01-01
The spin structure $g_{1}$ of the deuteron has been measured by COMPASS with unprecedented accuracy at low $x$, providing much more reliable values for the first moment $\\Gamma_{1}$ and for the quark spin contribution $\\Delta\\Sigma$. Difference-charge semi-inclusive asymmetries have been measured and seem to favor a flavor asymmetric polarized sea. The gluon polarization has been measured in the open-charm and high-$p_{t}$ channels. Large values of $\\Delta G$ are now unlikely.
Huang, X; Helmann, J D
1998-05-29
The promoter selectivity of RNA polymerase (RNAP) can be altered by the association with alternative sigma subunits. Bacillus subtilis hosts a multitude of sigma factors, several of which coordinate the complex developmental program culminating in endospore formation. Genome sequencing has revealed an unanticipated seven new sigma factors of the highly divergent extracytoplasmic function (ECF) sub-family. Virtually nothing is known regarding either the promoter selectivity or the target genes for these newly identified sigma factors. We have used saturation mutagenesis to define a promoter consensus for recognition by one such ECF sigma factor, sigma X. The resulting consensus sequence was used to identify candidate sigma X target sites. Three newly identified sigma X-dependent promoters precede genes encoding regulatory proteins: an AbrB homolog (Abh), a putative response regulator aspartate phosphatase (RapD), and a regulator of autolysin expression (LytR). sigma X also contributes to the expression of CsbB, a putative membrane-bound glucosyl transferase that is partially controlled by the sigma B stress response sigma factor. Since LytR modulates the expression of the major autolytic amidase and CsbB may function in peptidoglycan synthesis or modification, we suggest that sigma X participates in the regulation of peptidoglycan synthesis and turnover.
Energy Technology Data Exchange (ETDEWEB)
Babinski, A.; Li, G.; Jagadish, C. [The Australian National University, ACT (Australia). Institute of Advanced Studies, Research School of Physical Sciences and Engineering, Department of Electronic Materials Engineering
1998-07-01
The effect of doping concentration on electrical properties of Si {delta}-doped pseudomorphic In{sub 0} {sub .2}Ga{sub 0.} {sub 8}As/GaAs quantum wells (QWs) was examined in this work. Magnetotransport measurements were carried out in the magnetic fields up to 12 T in the dark at the temperature of T=1.7 K. The results were analysed using the fast Fourier transform (FFT). It was found that one electron subband was occupied in the QW with the doping concentrations of 2.3 x 10{sup 12} or 6.0 x 10{sup 12} cm{sup -2}. The parallel conduction was present in both samples, which increased with an increase of Si {delta}-doping concentration. The well-developed plateaus arising from the quantised Hall effect were observed in the Si {delta}-doped In{sub 0.} {sub 2}Ga{sub 0.} {sub 8}As/GaAs QW with reduced parallel conduction. The two subbands remain occupied within the V-shaped potential well formed at the Si doping plane when the Si {delta}-doping concentration was high. The results of measurements in tilted magnetic fields, confirming the attribution of FFT peaks to the particular 2DEG systems, are also presented.
DEFF Research Database (Denmark)
Qiu, Weimin; Abdallah, Basem; Kassem, Moustapha
DLK1/FA1 (delta-like 1/fetal antigen-1) is a negative regulator of bone mass that acts to inhibit osteoblast differentiation and stimulate osteoclast differentiation. However, the molecular mechanisms underlying these effects are not known. Thus, we studied the effect of DLK1/FA1 on different...
A High Performance Spread Spectrum Clock Generator Using Two-Point Modulation Scheme
Kao, Yao-Huang; Hsieh, Yi-Bin
A new spread spectrum clock generator (SSCG) using two-point delta-sigma modulation is presented in this paper. Not only the divider is varied, but also the voltage controlled oscillator is modulated. This technique can enhance the modulation bandwidth so that the effect of EMI suppression is improved with lower order ΣΔ modulator and can simultaneously optimize the jitter and the modulation profile. In addition, the method of two-path is applied to the loop filter to reduce the capacitance value such that the total integration can be achieved. The proposed SSCG has been fabricated in a 0.35μm CMOS process. The clock of 400MHz with center spread ratios of 1.25% and 2.5% are verified. The peak EMI reduction is 19.73dB for the case of 2.5%. The size of chip area is 0.90×0.89mm2.
Gauging the Poisson sigma model
Zucchini, Roberto
2008-01-01
We show how to carry out the gauging of the Poisson sigma model in an AKSZ inspired formulation by coupling it to the a generalization of the Weil model worked out in ref. arXiv:0706.1289 [hep-th]. We call the resulting gauged field theory, Poisson--Weil sigma model. We study the BV cohomology of the model and show its relation to Hamiltonian basic and equivariant Poisson cohomology. As an application, we carry out the gauge fixing of the pure Weil model and of the Poisson--Weil model. In the first case, we obtain the 2--dimensional version of Donaldson--Witten topological gauge theory, describing the moduli space of flat connections on a closed surface. In the second case, we recover the gauged A topological sigma model worked out by Baptista describing the moduli space of solutions of the so--called vortex equations.
The extracytoplasmic function (ECF) sigma factors.
Helmann, John D
2002-01-01
Bacterial sigma (sigma) factors are an essential component of RNA polymerase and determine promoter selectivity. The substitution of one sigma factor for another can redirect some or all of the RNA polymerase in a cell to activate the transcription of genes that would otherwise be silent. As a class, alternative sigma factors play key roles in coordinating gene transcription during various stress responses and during morphological development. The extracytoplasmic function (ECF) sigma factors are small regulatory proteins that are quite divergent in sequence relative to most other sigma factors. Many bacteria, particularly those with more complex genomes, contain multiple ECF sigma factors and these regulators often outnumber all other types of sigma factor combined. Examples include Bacillus subtilis (7 ECF sigma factors), Mycobacterium tuberculosis (10), Caulobacter crescentus (13), Pseudomonas aeruginosa (approximately 19), and Streptomyces coelicolor (approximately 50). The roles and mechanisms of regulation for these various ECF sigma factors are largely unknown, but significant progress has been made in selected systems. As a general trend, most ECF sigma factors are cotranscribed with one or more negative regulators. Often, these include a transmembrane protein functioning as an anti-sigma factor that binds, and inhibits, the cognate sigma factor. Upon receiving a stimulus from the environment, the sigma factor is released and can bind to RNA polymerase to stimulate transcription. In many ways, these anti-sigma:sigma pairs are analogous to the more familiar two-component regulatory systems consisting of a transmembrane histidine protein kinase and a DNA-binding response regulator. Both are mechanisms of coordinating a cytoplasmic transcriptional response to signals perceived by protein domains external to the cell membrane. Here, I review current knowledge of some of the better characterized ECF sigma factors, discuss the variety of experimental approaches
Spectra of conformal sigma models
Energy Technology Data Exchange (ETDEWEB)
Tlapak, Vaclav
2015-04-15
In this thesis the spectra of conformal sigma models defined on (generalized) symmetric spaces are analysed. The spaces where sigma models are conformal without the addition of a Wess-Zumino term are supermanifolds, in other words spaces that include fermionic directions. After a brief review of the general construction of vertex operators and the background field expansion, we compute the diagonal terms of the one-loop anomalous dimensions of sigma models on semi-symmetric spaces. We find that the results are formally identical to the symmetric case. However, unlike for sigma models on symmetric spaces, off diagonal terms that lead to operator mixing are also present. These are not computed here. We then present a detailed analysis of the one-loop spectrum of the supersphere S{sup 3} {sup vertical} {sup stroke} {sup 2} sigma model as one of the simplest examples. The analysis illustrates the power and simplicity of the construction. We use this data to revisit a duality with the OSP(4 vertical stroke 2) Gross-Neveu model that was proposed by Candu and Saleur. With the help of a recent all-loop result for the anomalous dimension of (1)/(2)BPS operators of Gross-Neveu models, we are able to recover the entire zero-mode spectrum of the supersphere model. We also argue that the sigma model constraints and its equations of motion are implemented correctly in the Gross-Neveu model, including the one-loop data. The duality is further supported by a new all-loop result for the anomalous dimension of the ground states of the sigma model. However, higher-gradient operators cannot be completely recovered. It is possible that this discrepancy is related to a known instability of the sigma model. The instability of sigma models is due to symmetry preserving high-gradient operators that become relevant at arbitrarily small values of the coupling. This feature has been observed long ago in one-loop calculations of the O(N)-vector model and soon been realized to be a generic
Szabo, Attila; Kovacs, Attila; Frecska, Ede; Rajnavolgyi, Eva
2014-01-01
The orphan receptor sigma-1 (sigmar-1) is a transmembrane chaperone protein expressed in both the central nervous system and in immune cells. It has been shown to regulate neuronal differentiation and cell survival, and mediates anti-inflammatory responses and immunosuppression in murine in vivo models. Since the details of these findings have not been elucidated so far, we studied the effects of the endogenous sigmar-1 ligands N,N-dimethyltryptamine (NN-DMT), its derivative 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and the synthetic high affinity sigmar-1 agonist PRE-084 hydrochloride on human primary monocyte-derived dendritic cell (moDCs) activation provoked by LPS, polyI:C or pathogen-derived stimuli to induce inflammatory responses. Co-treatment of moDC with these activators and sigma-1 receptor ligands inhibited the production of pro-inflammatory cytokines IL-1β, IL-6, TNFα and the chemokine IL-8, while increased the secretion of the anti-inflammatory cytokine IL-10. The T-cell activating capacity of moDCs was also inhibited, and dimethyltryptamines used in combination with E. coli or influenza virus as stimulators decreased the differentiation of moDC-induced Th1 and Th17 inflammatory effector T-cells in a sigmar-1 specific manner as confirmed by gene silencing. Here we demonstrate for the first time the immunomodulatory potential of NN-DMT and 5-MeO-DMT on human moDC functions via sigmar-1 that could be harnessed for the pharmacological treatment of autoimmune diseases and chronic inflammatory conditions of the CNS or peripheral tissues. Our findings also point out a new biological role for dimethyltryptamines, which may act as systemic endogenous regulators of inflammation and immune homeostasis through the sigma-1 receptor.
Directory of Open Access Journals (Sweden)
Attila Szabo
Full Text Available The orphan receptor sigma-1 (sigmar-1 is a transmembrane chaperone protein expressed in both the central nervous system and in immune cells. It has been shown to regulate neuronal differentiation and cell survival, and mediates anti-inflammatory responses and immunosuppression in murine in vivo models. Since the details of these findings have not been elucidated so far, we studied the effects of the endogenous sigmar-1 ligands N,N-dimethyltryptamine (NN-DMT, its derivative 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT and the synthetic high affinity sigmar-1 agonist PRE-084 hydrochloride on human primary monocyte-derived dendritic cell (moDCs activation provoked by LPS, polyI:C or pathogen-derived stimuli to induce inflammatory responses. Co-treatment of moDC with these activators and sigma-1 receptor ligands inhibited the production of pro-inflammatory cytokines IL-1β, IL-6, TNFα and the chemokine IL-8, while increased the secretion of the anti-inflammatory cytokine IL-10. The T-cell activating capacity of moDCs was also inhibited, and dimethyltryptamines used in combination with E. coli or influenza virus as stimulators decreased the differentiation of moDC-induced Th1 and Th17 inflammatory effector T-cells in a sigmar-1 specific manner as confirmed by gene silencing. Here we demonstrate for the first time the immunomodulatory potential of NN-DMT and 5-MeO-DMT on human moDC functions via sigmar-1 that could be harnessed for the pharmacological treatment of autoimmune diseases and chronic inflammatory conditions of the CNS or peripheral tissues. Our findings also point out a new biological role for dimethyltryptamines, which may act as systemic endogenous regulators of inflammation and immune homeostasis through the sigma-1 receptor.
Energy Technology Data Exchange (ETDEWEB)
Meot-Reymond, S
1996-12-31
Physical properties of actinide metals are essentially ruled by the 5f electrons localization. From a theoretically point of view, this localization is more important in the {delta}-phase than in the {alpha}-one. To compare their magnetic behaviour, low temperature magnetic susceptibility measurements have been performed and previous-resistivity data have been analysed. Experimental results and theoretical data can be conciliate by the existence of a Kondo effect in the {delta}-Pu phase. (author) 63 refs.
Attila Szabo; Attila Kovacs; Ede Frecska; Eva Rajnavolgyi
2014-01-01
The orphan receptor sigma-1 (sigmar-1) is a transmembrane chaperone protein expressed in both the central nervous system and in immune cells. It has been shown to regulate neuronal differentiation and cell survival, and mediates anti-inflammatory responses and immunosuppression in murine in vivo models. Since the details of these findings have not been elucidated so far, we studied the effects of the endogenous sigmar-1 ligands N,N-dimethyltryptamine (NN-DMT), its derivative 5-methoxy-N,N-dim...
Attila Szabo; Attila Kovacs; Ede Frecska; Eva Rajnavolgyi
2014-01-01
The orphan receptor sigma-1 (sigmar-1) is a transmembrane chaperone protein expressed in both the central nervous system and in immune cells. It has been shown to regulate neuronal differentiation and cell survival, and mediates anti-inflammatory responses and immunosuppression in murine in vivo models. Since the details of these findings have not been elucidated so far, we studied the effects of the endogenous sigmar-1 ligands N,N-dimethyltryptamine (NN-DMT), its derivative 5-methoxy-N,N-dim...
Polarimetric observations of $\\sigma$ Orionis E
Carciofi, Alex C; Townsend, Richard H D; Bjorkman, Jon E
2013-01-01
Some massive stars possess strong magnetic fields that confine plasma in the circumstellar environment. These \\textit{magnetospheres} have been studied spectroscopically, photometrically and, more recently, interferometrically. Here we report on the first firm detection of a magnetosphere in continuum linear polarization, as a result of monitoring of $\\sigma$\\,Ori\\,E at the Pico dos Dias Observatory. {The non-zero intrinsic polarization indicates an asymmetric structure, whose minor elongation axis is oriented $150\\fdg0$ east of the celestial north.} A modulation of the polarization was observed, with a period of half of the rotation period, which supports the theoretical prediction of the presence of two diametrally opposed, co-rotating blobs of gas. A phase lag of -0.085 was detected between the polarization minimum and the primary minimum of the light curve, suggestive of a complex shape of the plasma clouds. We present a preliminary analysis of the data with the Rigidly Rotating Magnetosphere model, which...
Six Sigma in healthcare delivery.
Liberatore, Matthew J
2013-01-01
The purpose of this paper is to conduct a comprehensive review and assessment of the extant Six Sigma healthcare literature, focusing on: application, process changes initiated and outcomes, including improvements in process metrics, cost and revenue. Data were obtained from an extensive literature search. Healthcare Six Sigma applications were categorized by functional area and department, key process metric, cost savings and revenue generation (if any) and other key implementation characteristics. Several inpatient care areas have seen most applications, including admission, discharge, medication administration, operating room (OR), cardiac and intensive care. About 42.1 percent of the applications have error rate as their driving metric, with the remainder focusing on process time (38 percent) and productivity (18.9 percent). While 67 percent had initial improvement in the key process metric, only 10 percent reported sustained improvement. Only 28 percent reported cost savings and 8 percent offered revenue enhancement. These results do not favorably assess Six Sigma's overall effectiveness and the value it offers healthcare. Results are based on reported applications. Future research can include directly surveying healthcare organizations to provide additional data for assessment. Future application should emphasize obtaining improvements that lead to significant and sustainable value. Healthcare staff can use the results to target promising areas. This article comprehensively assesses Six Sigma healthcare applications and impact.
Tawfik, Abdel Nasser; Hussein, M T
2016-01-01
In mean field approximation, the grand canonical potential of SU(3) Polyakov linear-$\\sigma$ model (PLSM) is analysed for chiral phase-transition, $\\sigma_l$ and $\\sigma_s$ and for deconfinement order-parameters, $\\phi$ and $\\phi^*$ of light- and strange-quarks, respectively. Various PLSM parameters are determined from the assumption of global minimization of the real part of the potential. Then, we have calculated the subtracted condensates ($\\Delta_{l,s}$). All these results are compared with recent lattice QCD simulations. Accordingly, essential PLSM parameters are determined. The modelling of the relaxation time is utilized in estimating the conductivity properties of the QCD matter in thermal medium, namely electric [$\\sigma_{el}(T)$] and heat [$\\kappa(T)$] conductivities. We found that the PLSM results on the electric conductivity and on the specific heat agree well with the available lattice QCD calculations. Also, we have calculated bulk and shear viscosities normalized to the thermal entropy, $\\xi/s$...
Energy Technology Data Exchange (ETDEWEB)
Widesott, Lamberto; Lomax, Antony J.; Schwarz, Marco [AtreP, Agenzia Provinciale per la Protonterapia, 38122 Trento (Italy); Paul Scherrer Institute, 5232 Villigen (Switzerland); AtreP, Agenzia Provinciale per la Protonterapia, 38122 Trento (Italy)
2012-03-15
Purpose: To assess the quality of dose distributions in real clinical cases for different dimensions of scanned proton pencil beams. The distance between spots (i.e., the grid of delivery) is optimized for each dimension of the pencil beam. Methods: The authors vary the {sigma} of the initial Gaussian size of the spot, from {sigma}{sub x} = {sigma}{sub y} = 3 mm to {sigma}{sub x} = {sigma}{sub y} = 8 mm, to evaluate the impact of the proton beam size on the quality of intensity modulated proton therapy (IMPT) plans. The distance between spots, {Delta}x and {Delta}y, is optimized on the spot plane, ranging from 4 to 12 mm (i.e., each spot size is coupled with the best spot grid resolution). In our Hyperion treatment planning system (TPS), constrained optimization is applied with respect to the organs at risk (OARs), i.e., the optimization tries to satisfy the dose objectives in the planning target volume (PTV) as long as all planning objectives for the OARs are met. Three-field plans for a nasopharynx case, two-field plans for a prostate case, and two-field plans for a malignant pleural mesothelioma case are considered in our analysis. Results: For the head and neck tumor, the best grids (i.e., distance between spots) are 5, 4, 6, 6, and 8 mm for {sigma} = 3, 4, 5, 6, and 8 mm, respectively. {sigma} {<=} 5 mm is required for tumor volumes with low dose and {sigma}{<=} 4 mm for tumor volumes with high dose. For the prostate patient, the best grid is 4, 4, 5, 5, and 5 mm for {sigma} = 3, 4, 5, 6, and 8 mm, respectively. Beams with {sigma} > 3 mm did not satisfy our first clinical requirement that 95% of the prescribed dose is delivered to more than 95% of prostate and proximal seminal vesicles PTV. Our second clinical requirement, to cover the distal seminal vesicles PTV, is satisfied for beams as wide as {sigma} = 6 mm. For the mesothelioma case, the low dose PTV prescription is well respected for all values of {sigma}, while there is loss of high dose PTV coverage
Bethe Ansatz in Stringy Sigma Models
Klose, T.; Zarembo, K.
2006-01-01
We compute the exact S-matrix and give the Bethe ansatz solution for three sigma-models which arise as subsectors of string theory in AdS(5)xS(5): Landau-Lifshitz model (non-relativistic sigma-model on S(2)), Alday-Arutyunov-Frolov model (fermionic sigma-model with su(1|1) symmetry), and Faddeev-Reshetikhin model (string sigma-model on S(3)xR).
Lean Six Sigma in financial services
de Koning, H.; Does, R.J.M.M.; Bisgaard, S.
2008-01-01
Lean Thinking and Six Sigma are typically considered as separate approaches to process innovation, with complementary strengths. When combined as Lean Six Sigma, this approach provides a unified framework for systematically developing innovations. Lean Six Sigma can also bring about significant resu
Lean Six Sigma in financial services
de Koning, H.; Does, R.J.M.M.; Bisgaard, S.
2008-01-01
Lean Thinking and Six Sigma are typically considered as separate approaches to process innovation, with complementary strengths. When combined as Lean Six Sigma, this approach provides a unified framework for systematically developing innovations. Lean Six Sigma can also bring about significant
K to \\pi\\pi decays and the K to \\sigma weak amplitude
Trofimenkoff, N N
2012-01-01
We use a twice-subtracted partial-wave dispersion relation in the elastic unitarity approximation for final-state interactions to study the amplitude for the delta I = 1/2 CP-conserving weak process K+spurion->pi+pi. We use a simple parameterization to approximate the low energy I = 0 S-wave pipi->pipi scattering phase shift and extract the residue of the sigma pole in the weak amplitude obtained from the dispersion relation. Using this residue, we relate the K->pipi decay amplitude, the weak amplitude at the soft pion point and the K->sigma weak amplitude.
Delta III—an evolutionary delta growth
Arvesen, R. J.; Simpson, J. S.
1996-03-01
In order to remain competitive in the future and expand the McDonnell Douglas Aerospace market share, MDA has developed an expendable launch system strategy that devices cost-effective launch systems from the Delta II with a growth vehicle configuration called Delta III. The Delta III evolves from the Delta II launch system through development of a larger payload fairing (4-meter diameter), new cryogenically propelled upper stage, new first stage fuel tank, and larger strap-on solid rocket motors. We are developing the Delta III using Integrated Product Development Teams that capitalize on the experience base that has led us to a world record breaking mission success of 49 consecutive Delta II missions. The Delta III first-launch capability is currently planned for the spring of 1998 in support of our first spacecraft customer, Hughes Space and Communications International.
The sausage sigma model revisited
Suneeta, Vardarajan
2015-06-01
Fateev’s sausage sigma models in two and three dimensions are known to be integrable. We study their stability under renormalization group (RG) flow in the target space by using results from the mathematics of Ricci flow. We show that the three-dimensional sausage is unstable, whereas the two-dimensional sausage appears to be stable at least at leading order as it approaches the sphere. We speculate that the stability results obtained are linked to the classification of ancient solutions to Ricci flow (i.e., sigma models that are nonperturbative in the infrared regime) in two and three dimensions. We also describe a class of perturbations of the three-dimensional sausage (with the same continuous symmetries) which remarkably decouple. This indicates that there could be a new solution to RG flow, which is described at least perturbatively as a deformation of the sausage.
Topological sigma models on supermanifolds
Energy Technology Data Exchange (ETDEWEB)
Jia, Bei, E-mail: beijia@physics.utexas.edu
2017-02-15
This paper concerns constructing topological sigma models governing maps from semirigid super Riemann surfaces to general target supermanifolds. We define both the A model and B model in this general setup by defining suitable BRST operators and physical observables. Using supersymmetric localization, we express correlation functions in these theories as integrals over suitable supermanifolds. In the case of the A model, we obtain an integral over the supermoduli space of “superinstantons”. The language of supergeometry is used extensively throughout this paper.
Topological sigma models on supermanifolds
Jia, Bei
2017-02-01
This paper concerns constructing topological sigma models governing maps from semirigid super Riemann surfaces to general target supermanifolds. We define both the A model and B model in this general setup by defining suitable BRST operators and physical observables. Using supersymmetric localization, we express correlation functions in these theories as integrals over suitable supermanifolds. In the case of the A model, we obtain an integral over the supermoduli space of "superinstantons". The language of supergeometry is used extensively throughout this paper.
Topological Sigma Models On Supermanifolds
Jia, Bei
2016-01-01
This paper concerns constructing topological sigma models governing maps from semirigid super Riemann surfaces to general target supermanifolds. We define both the A model and B model in this general setup by defining suitable BRST operators and physical observables. Using supersymmetric localization, we express correlation functions in these theories as integrals over suitable supermanifolds. In the case of the A model, we obtain an integral over the supermoduli space of "superinstantons". The language of supergeometry is used extensively throughout this paper.
de Koning, Henk; Verver, John P S; van den Heuvel, Jaap; Bisgaard, Soren; Does, Ronald J M M
2006-01-01
Healthcare, as with any other service operation, requires systematic innovation efforts to remain competitive, cost efficient, and up-to-date. This article outlines a methodology and presents examples to illustrate how principles of Lean Thinking and Six Sigma can be combined to provide an effective framework for producing systematic innovation efforts in healthcare. Controlling healthcare cost increases, improving quality, and providing better healthcare are some of the benefits of this approach.
Optimal Six-Sigma Level in TFT-LCD Manufacturing: A Case Study
Directory of Open Access Journals (Sweden)
Jen-Ming Chenand Tsung-Te Cheng
2010-11-01
Full Text Available Abstract. This paper deals with six-sigma project decision-making in TFT-LCDmanufacturing using multi-objective goal programming approach to assist theproject leader in deciding process improving opportunities. The model considers amulti-stage process rolled throughput yield in a TFT Liquid Crystal Display (LCDmajor Array, Cell, and Module process. Meanwhile, the other factors such asinvestment cost, profit, and expected sigma level will be taken into consideration inthe model. Numerical result shows an organization can reap the profit through thesix-sigma project implementation.
The sigma Orionis substellar population
Barrado y Navascués, D; Mundt, R; Martín, E L; Rebolo, R; Zapatero-Osorio, M R; Bailer-Jones, C A L; Navascu\\'es, David Barrado y; Mundt, Reinhard; Mart\\'{\\i}n, Eduardo L.; Rebolo, Rafael; Osorio, Mar\\'{\\i}a Rosa Zapatero; Bailer-Jones, Coryn A.L.
2003-01-01
VLT/FORS spectroscopy and 2MASS near-infrared photometry, together with previously known data, have been used to establish the membership and the properties of a sample of low-mass candidate members of the sigma Orionis cluster with masses spanning from 1 Msun down to about 0.013 Msun (i.e., deuterium-burning mass limit). We have observed K-band infrared excess and remarkably intense H(alpha) emission in various cluster members, which, in addition to the previously detected forbidden emision lines and the presence of LiI in absorption at 6708 A, have allowed us to tentatively classify sigma Orionis members as classical or weak-line TTauri stars and substellar analogs. Variability of the H(alpha) line has been investigated and detected in some objects. Based on the K-band infrared excesses and the intensity of H(alpha) emission, we estimate that the minimum disk frequency of the sigma Orionis low-mass population is in the range 5-12%.
Sigma-class glutathione transferases.
Flanagan, Jack U; Smythe, Mark L
2011-05-01
Mammalian cytosolic glutathione transferases (GSTs) can be grouped into seven classes. Of these, the sigma class is also widely distributed in nature, with isoforms found in both vertebrates and invertebrates. It contains examples of proteins that have evolved specialized functions, such as the cephalopod lens S-crystallins, the mammalian hematopoietic prostaglandin D(2) synthase, and the helminth 28-kDa antigen. In mammals, the sigma-class GST has both anti- and proinflammatory functions, depending on the type of immune response, and an immunomodulatory function is also associated with the enzyme from helminth parasites. In the fly, it is associated with a specific detoxication activity toward lipid oxidation products. Mice genetically depleted of the sigma-class GST, or transgenically overexpressing it, have provided insight into the physiological roles of the GST. Inhibitors of the mammalian enzyme developed by structure-based methods are effective in controlling allergic response. This review covers the structure, function, and pharmacology of vertebrate and invertebrate GSTs.
The sausage sigma model revisited
Suneeta, Vardarajan
2014-01-01
Fateev's sausage sigma models in two and three dimensions are known to be integrable. We study their stability under RG flow in the target space by using results from the mathematics of Ricci flow. We show that the three dimensional sausage is unstable, whereas the two dimensional sausage appears to be stable at least at leading order as it approaches the sphere. The $n$-sphere, corresponding to the integrable O(n) sigma model, is geometrically stable and an attractor for nearby solutions to RG flow. We speculate that the stability results obtained seem to be linked to the classification of ancient solutions to Ricci flow (i.e., sigma models which are asymptotically free in the UV and nontrivial in the IR) in two and three dimensions. We also describe a class of perturbations of the three dimensional sausage (with the same continuous symmetries) which remarkably decouple. This indicates that there could be a new solution to RG flow which is described at least perturbatively as a deformation of the sausage.
Sign ambiguity in the K Sigma channel
Anisovich, A V; Nikonov, V A; Sarantsev, A V; Thoma, U
2013-01-01
Ambiguities of the signs of $N\\to \\Sigma K$ coupling constants are studied in a multichannel partial wave analysis of a large body of pion and photo-induced reactions. It is shown that the signs are not free from some ambiguities, and further experimental data are needed. Data on the reactions $\\pi^+p\\to \\Sigma^+K^+$ and $\\gamma p\\to K^+\\Sigma^0$ define rather well the isospin 3/2 contributions to these channels. However the lack of information on polarization observables for the reactions $\\pi^-p\\to \\Sigma^0K^0$, $\\pi^-p\\to \\Sigma^-K^+$ and $\\gamma p\\to K^0\\Sigma^+$ does not allow us to fix uniquely the signs of $N\\to \\Sigma K$ coupling constants. As a consequence, also the contributions of nucleon resonances to these channels remain uncertain.
Ousley, Gilbert W., Sr.
1991-12-01
The utilization of the Delta 2 as the vehicle for launching Aristoteles into its near Sun synchronous orbit is addressed. Delta is NASA's most reliable launch vehicle and is well suited for placing the present Aristoteles spacecraft into a 400 m circular orbit. A summary of some of the Delta 2 flight parameters is presented. Diagrams of a typical Delta 2 two stage separation are included along with statistics on delta reliability and launch plans.
Bacterial Sigma Factors and Anti-Sigma Factors: Structure, Function and Distribution.
Paget, Mark S
2015-06-26
Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP) that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (Group 1) that directs the bulk of transcription during active growth, and structurally-related alternative sigma factors (Groups 2-4) that control a wide variety of adaptive responses such as morphological development and the management of stress. A recurring theme in sigma factor control is their sequestration by anti-sigma factors that occlude their RNAP-binding determinants. Sigma factors are then released through a wide variety of mechanisms, often involving branched signal transduction pathways that allow the integration of distinct signals. Three major strategies for sigma release are discussed: regulated proteolysis, partner-switching, and direct sensing by the anti-sigma factor.
Juang, Y L; Helmann, J D
1994-02-04
Sigma factor (sigma) is a dissociable subunit of bacterial RNA polymerase that determines promoter recognition. It has been proposed that a cluster of highly conserved aromatic amino acids in bacterial sigma factors (region 2.3) defines a melting motif that functions in strand-separation during open complex formation. We demonstrate that many alterations in region 2.3 of the Bacillus subtilis sigma A protein specifically impair open complex formation. The region 2.3 mutations can be grouped in three classes: (1) mutations that do not significantly affect promoter recognition or melting; (2) mutations that lead to cold-sensitive transcription of linear templates; and (3) mutations that lead to little activity on linear templates but retain activity at high temperatures on supercoiled templates. RNA polymerase holoenzymes containing sigma factor melting mutants (classes 2 and 3) form predominantly closed complexes at 40 degrees C and are defective for RNA synthesis when initiation is rate-limiting. The melting defect of these mutant sigma factors is suppressed by template supercoiling, but further enhanced by inclusion of the auxiliary RNA polymerase subunit delta. Consequently, in the presence of the delta polypeptide, the mutant holoenzymes display cold-sensitive transcription on supercoiled templates: conditions which mimic the in vivo situation. A subset of these mutations also affects promoter selectivity, suggesting that region 2.3 may participate in both -10 recognition and DNA melting.
Sigma Factors for Cyanobacterial Transcription
Directory of Open Access Journals (Sweden)
Sousuke Imamura
2009-04-01
Full Text Available Cyanobacteria are photosynthesizing microorganisms that can be used as a model for analyzing gene expression. The expression of genes involves transcription and translation. Transcription is performed by the RNA polymerase (RNAP holoenzyme, comprising a core enzyme and a sigma (σ factor which confers promoter selectivity. The unique structure, expression, and function of cyanobacterial σ factors (and RNAP core subunits are summarized here based on studies, reported previously. The types of promoter recognized by the σ factors are also discussed with regard to transcriptional regulation.
Topological sigma models on supermanifolds
Directory of Open Access Journals (Sweden)
Bei Jia
2017-02-01
Full Text Available This paper concerns constructing topological sigma models governing maps from semirigid super Riemann surfaces to general target supermanifolds. We define both the A model and B model in this general setup by defining suitable BRST operators and physical observables. Using supersymmetric localization, we express correlation functions in these theories as integrals over suitable supermanifolds. In the case of the A model, we obtain an integral over the supermoduli space of “superinstantons”. The language of supergeometry is used extensively throughout this paper.
Cohomological reduction of sigma models
Energy Technology Data Exchange (ETDEWEB)
Candu, Constantin; Mitev, Vladimir; Schomerus, Volker [DESY, Hamburg (Germany). Theory Group; Creutzig, Thomas [North Carolina Univ., Chapel Hill, NC (United States). Dept. of Physics and Astronomy
2010-01-15
This article studies some features of quantum field theories with internal supersymmetry, focusing mainly on 2-dimensional non-linear sigma models which take values in a coset superspace. It is discussed how BRST operators from the target space super- symmetry algebra can be used to identify subsectors which are often simpler than the original model and may allow for an explicit computation of correlation functions. After an extensive discussion of the general reduction scheme, we present a number of interesting examples, including symmetric superspaces G/G{sup Z{sub 2}} and coset superspaces of the form G/G{sup Z{sub 4}}. (orig.)
A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator
DEFF Research Database (Denmark)
Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre
The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub......-threshold to saturation. By using the 1/f-noise reduction circuit which is based on the switched bias technique, the simulations indicate that less noise is transferred to the output when the 1/f-noise reduction circuit is used. The phase noise of the proposed VCO is improved by 7.6% while maintaining tuning...
Conserved and Variable Functions of the sigma(E Stress Response in Related Genomes.
Directory of Open Access Journals (Sweden)
2005-12-01
Full Text Available Bacteria often cope with environmental stress by inducing alternative sigma (sigma factors, which direct RNA polymerase to specific promoters, thereby inducing a set of genes called a regulon to combat the stress. To understand the conserved and organism-specific functions of each sigma, it is necessary to be able to predict their promoters, so that their regulons can be followed across species. However, the variability of promoter sequences and motif spacing makes their prediction difficult. We developed and validated an accurate promoter prediction model for Escherichia coli sigma(E, which enabled us to predict a total of 89 unique sigma(E-controlled transcription units in E. coli K-12 and eight related genomes. sigma(E controls the envelope stress response in E. coli K-12. The portion of the regulon conserved across genomes is functionally coherent, ensuring the synthesis, assembly, and homeostasis of lipopolysaccharide and outer membrane porins, the key constituents of the outer membrane of Gram-negative bacteria. The larger variable portion is predicted to perform pathogenesis-associated functions, suggesting that sigma(E provides organism-specific functions necessary for optimal host interaction. The success of our promoter prediction model for sigma(E suggests that it will be applicable for the prediction of promoter elements for many alternative sigma factors.
Resonances in the Sigma NN system
Gibson, B. F.; Afnan, I. R.
We first review certain unique aspects of few-body Lambda-hypernuclei and then explore the physics of Sigma-hypernuclei that would produce structure near the Sigma threshold in few-body elastic scattering and reactions. In particular, we discuss a predicted enhancement in the lambda(d) cross section near the Sigma NN threshold in terms of poles in the Tau = 0 Y N N amplitude. A brief discussion of anticipated poles in the Tau = 1 amplitudes is also given.
The bi Hermitian topological sigma model
Zucchini, R
2006-01-01
BiHermitian geometry, discovered long ago by Gates, Hull and Roceck, is the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. By using the twisting procedure proposed by Kapustin and Li, we work out the type A and B topological sigma models for a general biHermtian target space, we write down the explicit expression of the sigma model's action and BRST transformations and present a computation of the topological gauge fermion.
Lean Six Sigma in financial services
Koning, H.; Does, R.J.M.M.; Bisgaard, S.
2008-01-01
Lean Thinking and Six Sigma are typically considered as separate approaches to process innovation, with complementary strengths. When combined as Lean Six Sigma, this approach provides a unified framework for systematically developing innovations. Lean Six Sigma can also bring about significant results and breakthrough improvements in financial services, as demonstrated with four case studies from Dutch multinational insurance companies. These cases demonstrate the importance of incremental i...
Delta Plaza kohvik = Delta Plaza cafe
2010-01-01
Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)
Delta Plaza kohvik = Delta Plaza cafe
2010-01-01
Tallinnas Pärnu mnt 141 asuva kohviku Delta Plaza sisekujundusest. Sisearhitektid Tiiu Truus ja Marja Viltrop (Stuudio Truus OÜ). Tiiu Truusi tähtsamate tööde loetelu. Büroohoone Delta Plaza arhitektid Marika Lõoke ja Jüri Okas (AB J. Okas & M. Lõoke)
Applying Sigma Metrics to Reduce Outliers.
Litten, Joseph
2017-03-01
Sigma metrics can be used to predict assay quality, allowing easy comparison of instrument quality and predicting which tests will require minimal quality control (QC) rules to monitor the performance of the method. A Six Sigma QC program can result in fewer controls and fewer QC failures for methods with a sigma metric of 5 or better. The higher the number of methods with a sigma metric of 5 or better, the lower the costs for reagents, supplies, and control material required to monitor the performance of the methods.
Separation of Delta S=0 and Delta S=1 in the response of {sup 12}C to 318 MeV protons
Energy Technology Data Exchange (ETDEWEB)
F. T. Baker; D. Beatty; L. Bimbot; V. Cupps; C. Djalali; R. W. Fergerson; C. Glashausser; G. Graw; A. Green; K. Jones; M. Morlet; S. K. Nanda; A. Sethi; B. H. Storm; W. Unkelbach; and A. Willis
1993-04-01
Angular distributions of the double-differential cross section d{sup 2} sigma/d Omega dE (sigma) and the spin-flip probability S{sub nn} have been measured for inclusive inelastic proton scattering from {sup 12}C at E{sub p}=318 MeV. Data have been obtained over an excitation energy range 9 MeV {le} E{sub x} {le} 42 MeV for laboratory scattering angles of 3{sup o}, 5{sup o}, 7{sup o}, 9{sup o}, 12{sup o}, 15{sup o}, and 18{sup o}. Multipole decompositions of angular distributions of both the spin-flip cross section sigma {sub SF} = sigma S{sub nn} and the estimated cross section for Delta S=0 transitions have been performed. The distribution of deduced Delta L=1, Delta S=0 (the giant-dipole resonance) strength peaks near E{sub x}=22 MeV; although there is apparently much more strength relative to the energy-weighted sum rule (EWSR) than expected, this appears to be an artifact of instrumental background at small angles. Approximately 55% of the EWSR for Delta L=2, Delta S=0 was observed spread uniformly across the spectrum with no evidence for a giant-quadrupole resonance. Angular distributions for sigma{sub SF} were analyzed using the predictions from random-phase approximation calculations for the nuclear structure and distorted-wave impulse approximation calculations for the scattering. These predictions are found to provide a good description of the sigma{sub SF} data above E{sub x}=25 MeV; values of S{sub nn} are predicted somewhat too low in this region.
Foufoula-Georgiou, E.; Tessler, Z. D.; Brondizio, E.; Overeem, I.; Renaud, F.; Sebesvari, Z.; Nicholls, R. J.; Anthony, E.
2016-12-01
Deltas are highly dynamic and productive environments: they are food baskets of the world, home to biodiverse and rich ecosystems, and they play a central role in food and water security. However, they are becoming increasingly vulnerable to risks arising from human activities, land subsidence, regional water management, global sea-level rise, and climate extremes. Our Belmont Forum DELTAS project (BF-DELTAS: Catalyzing actions towards delta sustainability) encompasses an international network of interdisciplinary research collaborators with focal areas in the Mekong, Ganges Brahmaputra, and the Amazon deltas. The project is organized around five main modules: (1) developing an analytical framework for assessing delta vulnerability and scenarios of change (Delta-SRES), (2) developing an open-acess, science-based integrative modeling framework for risk assessment and decision support (Delta-RADS), (3) developing tools to support quantitative mapping of the bio-physical and socio-economic environments of deltas and consolidate bio-physical and social data within shared data repositories (Delta-DAT), (4) developing Global Delta Vulnerability Indices (Delta-GDVI) that capture current and projected scenarios for major deltas around the world , and (5) collaborating with regional stakeholders to put the science, modeling, and data into action (Delta-ACT). In this talk, a research summary will be presented on three research domains around which significant collaborative work was developed: advancing biophysical classification of deltas, understanding deltas as coupled socio-ecological systems, and analyzing and informing social and environmental vulnerabilities in delta regions.
Narrow structure in [Lambda]d scattering near the [Sigma] threshold ([sub [Sigma
Energy Technology Data Exchange (ETDEWEB)
Gibson, B.F. (Los Alamos National Lab., NM (United States). Theoretical Div.); Afnan, I.R. (Flinders Univ. of South Australia, Bedford Park (Australia). School of Physical Sciences)
1992-09-14
A separable-potential, Faddeev-type calculation of [Lambda]-deuteron scattering near the threshold for [Sigma] production is shown to produce structure (a resonance peak) in the cross section which lies below the [Sigma] threshold for two different Y N ([Lambda]N - [Sigma]N coupled-channel) potential models. In one case the [Sigma]NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the pole lies above the threshold. (orig.).
Narrow structure in. Lambda. d scattering near the. Sigma. threshold ( sub. Sigma. sup 3 He states)
Energy Technology Data Exchange (ETDEWEB)
Gibson, B.F. (Los Alamos National Lab., NM (United States)); Afnan, I.R. (Flinders Univ. of South Australia, Bedford Park (Australia). School of Physical Sciences)
1991-01-01
A separable-potential, Faddeev-type calculation of {Lambda}-deuteron scattering near the threshold for {Sigma} production is shown to produce structure (a resonance peak) in the cross section which lies below the {Sigma} threshold for two different YN ({Lambda}N-{Sigma}N coupled-channel) potential models. In one case the {Sigma}NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold.
Bacterial Sigma Factors and Anti-Sigma Factors: Structure, Function and Distribution
Paget, Mark S.
2015-01-01
Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP) that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (Group 1) that directs the bulk of transcription during active growth, and structurally-related alternative sigma factors (Groups 2–4) that control ...
van Schaik, Willem; Abee, Tjakko
2005-04-01
The alternative sigma factor sigmaB modulates the stress response of several Gram-positive bacteria, including Bacillus subtilis and the food-borne human pathogens Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. In all these bacteria, sigmaB is responsible for the transcription of genes that can confer stress resistance to the vegetative cell. Recent findings indicate that sigmaB also plays an important role in antibiotic resistance, pathogenesis and cellular differentiation processes such as biofilm formation and sporulation. Although there are important differences in the regulation of sigmaB and in the set of genes regulated by sigmaB in B. subtilis, B. cereus, L. monocytogenes and S. aureus, there are also some conserved themes. A mechanistic understanding of the sigmaB activation processes and assessment of its regulon could provide tools for pathogen control and inactivation both in the food industry and clinical settings.
Sigma Receptors in Oncology : Therapeutic and Diagnostic Applications of Sigma Ligands
van Waarde, Aren; Rybczynska, Anna A.; K. Ramakrishnan, Nisha; Ishiwata, Kiichi; Elsinga, Philip H.; Dierckx, Rudi A. J. O.
2010-01-01
Sigma receptors (subtypes sigma-1 and sigma-2) are a unique class of binding sites expressed throughout the mammalian body. The endogenous ligand for these sites has not been identified, but steroid hormones (particularly progesterone), sphingolipid-derived amines and N,N-dimethyltryptamine can bind
Sigma Receptors in Oncology : Therapeutic and Diagnostic Applications of Sigma Ligands
van Waarde, Aren; Rybczynska, Anna A.; K. Ramakrishnan, Nisha; Ishiwata, Kiichi; Elsinga, Philip H.; Dierckx, Rudi A. J. O.
2010-01-01
Sigma receptors (subtypes sigma-1 and sigma-2) are a unique class of binding sites expressed throughout the mammalian body. The endogenous ligand for these sites has not been identified, but steroid hormones (particularly progesterone), sphingolipid-derived amines and N,N-dimethyltryptamine can bind
Energy Technology Data Exchange (ETDEWEB)
Spearing, Dane Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Safeguards Science and Technology Group (NEN-1)
2016-11-29
These are slides from a facility overview presentation for visiting agencies to Los Alamos National Laboratory (LANL). The TA-55 Plutonium Facility (PF-4) is discussed in detail. PF-4 is a unique resource for US plutonium programs. The basic design is flexible and has adapted to changing national needs. It is a robust facility with strong safety and security implementation. It supports a variety of national programs. It will continue for many years into the future. Sigma is then discussed in detail, which handles everything from hydrogen to uranium. It has been in long term service to the Nation (nearly 60 years). It has a flexible authorization basis to handle almost the entire periodic table. It has a wide breadth of prototyping and characterization capabilities. It has integrated program and line management.
Exploring the Supersymmetric $\\sigma$ Model
De Oliveira-Imbiriba, B C
1999-01-01
The purpose of this work is to present some basic concepts about the non-linear sigma model in a simple and direct way. We start with showing the bosonic model and the Wess-Zumino-Witten term, making some comments about its topological nature, and its association with the torsion. It is also shown that to cancel the quantum conformal anomaly the model should obey the Einstein equations. We provide a quick introduction about supersymmetry in chapter 2 to help the understanding the supersymmetric extension of the model. In the last chapter we present the supersymmetric model and its equations of motion. Finally we work-out the two-supersymmetry case, introducing the chiral as well as the twisted chiral fields, expliciting the very specific $SU(2)\\otimes U(1)$ case.
Toselli, M; Tosetti, P; Taglietti, V
1999-01-01
The voltage-dependent inhibition of N-type Ca2+ channel current by the delta-opioid agonist [D-pen2, D-pen5]-enkephalin (DPDPE) was investigated in the mammalian cell line NG108-15 with 10 microM nifedipine to block L-type channels, with whole-cell voltage clamp methods. In in vitro differentiated NG108-15 cells DPDPE reversibly decreased omega-conotoxin GVIA-sensitive Ba2+ currents in a concentration-dependent way. Inhibition was maximal with 1 microM DPDPE (66% at 0 mV) and was characterized by a slowing of Ba2+ current activation at low test potentials. Both inhibition and kinetic slowing were attenuated at more positive potentials and could be relieved up to 90% by strong conditioning depolarizations. The kinetics of removal of inhibition (de-inhibition) and of its retrieval (re-inhibition) were also voltage dependent. Both de-inhibition and re-inhibition were single exponentials and, in the voltage range from -20 to +10 mV, had significantly different time constants at a given membrane potential, the time course of re-inhibition being faster than that of de-inhibition. The kinetics of de-inhibition at -20 mV and of reinhibition at -40 mV were also concentration dependent, both processes becoming slower at lower agonist concentrations. The rate of de-inhibition at +80/+120 mV was similar to that of Ca2+ channel activation at the same potentials measured during application of DPDPE (approximately 7 ms), both processes being much slower than channel activation in controls (<1 ms). Moreover, the amplitude but not the time course of tail currents changed as the depolarization to +80/+120 mV was made longer. The state-dependent properties of DPDPE Ca2+ channel inhibition could be simulated by a model that assumes that inhibition by DPDPE results from voltage- and concentration-dependent binding of an inhibitory molecule to the N-type channel. PMID:10233071
van den Heuvel, J.; Does, R.J.M.M.; de Koning, H.
2006-01-01
Abstract Hospitals today face major challenges. Patients demand quality of care to be improved continuously. Health insurance companies demand the lowest possible prices. Lean Six Sigma is a program that can help healthcare providers to achieve these (seemingly) conflicting goals. Lean Six Sigma is
Six Sigma als blauwdruk voor de kenniseconomie.
de Mast, J.; Does, R.J.M.M.
2005-01-01
Abstract Six Sigma is zo langzamerhand een niet weg te denken programma voor kwaliteits- en efficiencyverbeteringen. Het heeft met name voor enorme successen gezorgd in productiebedrijven. Six Sigma ligt ook onder vuur: het zou een trend zijn die voorbij gaat. De auteurs van dit artikel zijn het van
Integrating the Many Facets of Six Sigma
de Mast, J.
2007-01-01
We seek to provide a unified characterization of Six Sigma by studying the phenomenon from the perspectives of business economics, organizational theory, competitive strategy and industrial statistics, and we pinpoint its core methodological principles. We describe Six Sigma as a prescriptive framew
De praktijk van Lean Six Sigma
Does, R.J.M.M.; de Koning, H.
2008-01-01
Zowel Lean als Six Sigma zijn benaderingen van kwaliteits- en efficiëntieverbetering die op dit moment sterk in de belangstelling staan van zowel de industrie als de dienstverlening. Lean Six Sigma integreert beide benaderingen. Ze wordt door sommigen gezien als panacee voor alle mogelijke organisat
van den Heuvel, J.; Does, R.J.M.M.; de Koning, H.
2006-01-01
Abstract Hospitals today face major challenges. Patients demand quality of care to be improved continuously. Health insurance companies demand the lowest possible prices. Lean Six Sigma is a program that can help healthcare providers to achieve these (seemingly) conflicting goals. Lean Six Sigma is
Six Sigma als blauwdruk voor de kenniseconomie.
de Mast, J.; Does, R.J.M.M.
2005-01-01
Abstract Six Sigma is zo langzamerhand een niet weg te denken programma voor kwaliteits- en efficiencyverbeteringen. Het heeft met name voor enorme successen gezorgd in productiebedrijven. Six Sigma ligt ook onder vuur: het zou een trend zijn die voorbij gaat. De auteurs van dit artikel zijn het van
Integrating the Many Facets of Six Sigma
de Mast, J.
2007-01-01
We seek to provide a unified characterization of Six Sigma by studying the phenomenon from the perspectives of business economics, organizational theory, competitive strategy and industrial statistics, and we pinpoint its core methodological principles. We describe Six Sigma as a prescriptive
Lean Six Sigma implementation and organizational culture.
Knapp, Susan
2015-01-01
The purpose of this paper is to examine the relationship between four organizational cultural types defined by the Competing Values Framework and three Lean Six Sigma implementation components - management involvement, use of Lean Six Sigma methods and Lean Six Sigma infrastructure. The study involved surveying 446 human resource and quality managers from 223 hospitals located in Maine, New Hampshire, Vermont, Massachusetts and Rhode Island using the Organizational Culture Assessment Instrument. Findings - In total, 104 completed responses were received and analyzed using multivariate analysis of variance. Follow-up analysis of variances showed management support was significant, F(3, 100)=4.89, p Six Sigma methods was also not significant, F(3, 100)=1.34, p=0.26, η2=0.04. Post hoc analysis identified group and development cultures having significant interactions with management support. The relationship between organizational culture and Lean Six Sigma in hospitals provides information on how specific cultural characteristics impact the Lean Six Sigma initiative key components. This information assists hospital staff who are considering implementing quality initiatives by providing an understanding of what cultural values correspond to effective Lean Six Sigma implementation. Managers understanding the quality initiative cultural underpinnings, are attentive to the culture-shared values and norm's influence can utilize strategies to better implement Lean Six Sigma.
POLARIMETRIC OBSERVATIONS OF {sigma} ORIONIS E
Energy Technology Data Exchange (ETDEWEB)
Carciofi, A. C.; Faes, D. M. [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900 Sao Paulo, SP (Brazil); Townsend, R. H. D. [Department of Astronomy, University of Wisconsin-Madison, Sterling Hall, 475 N. Charter Street, Madison, WI 53706 (United States); Bjorkman, J. E., E-mail: carciofi@usp.br [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States)
2013-03-20
Some massive stars possess strong magnetic fields that confine plasma in the circumstellar environment. These magnetospheres have been studied spectroscopically, photometrically, and, more recently, interferometrically. Here we report on the first firm detection of a magnetosphere in continuum linear polarization, as a result of monitoring {sigma} Ori E at the Pico dos Dias Observatory. The non-zero intrinsic polarization indicates an asymmetric structure whose minor elongation axis is oriented 150. Degree-Sign 0 east of the celestial north. A modulation of the polarization was observed with a period of half of the rotation period, which supports the theoretical prediction of the presence of two diametrally opposed, corotating blobs of gas. A phase lag of -0.085 was detected between the polarization minimum and the primary minimum of the light curve, suggestive of a complex shape of the plasma clouds. We present a preliminary analysis of the data with the Rigidly Rotating Magnetosphere model, which could not reproduce simultaneously the photometric and polarimetric data. A toy model comprising two spherical corotating blobs joined by a thin disk proved more successful in reproducing the polarization modulation. With this model we were able to determine that the total scattering mass of the thin disk is similar to the mass of the blobs (2M{sub b}/M{sub d} = 1.2) and that the blobs are rotating counterclockwise on the plane of the sky. This result shows that polarimetry can provide a diagnostic of the geometry of clouds, which will serve as an important constraint for improving the Rigidly Rotating Magnetosphere model.
Binding of kappa- and sigma-opiates in rat brain
Energy Technology Data Exchange (ETDEWEB)
Wolozin, B.L.; Nishimura, S.; Pasternak, G.W.
1982-06-01
Detailed displacements of (/sup 3/H)dihydromorphine by ketocyclazocine and SKF 10,047, (/sup 3/H)ethylketocyclazocine by SKF 10,047, and (/sup 3/H)SKF 10,047 by ketocyclazocine are all multiphasic, suggesting multiple binding sites. After treating brain tissue in vitro with naloxazone, all displacements lose the initial inhibition of /sup 3/H-ligand binding by low concentrations of unlabeled drugs. Together with Scatchard analysis of saturation experiments, these studies suggest a common site which binds mu-, kappa, and sigma-opiates and enkephalins equally well and with highest affinity (KD less than 1 nM). The ability of unlabeled drugs to displace the low affinity binding of (/sup 3/H)dihydromorphine (KD . 3 nM), (/sup 3/H)ethylketocyclazocine (KD . 4 nM), (/sup 3/H)SKF 10,047 (KD . 6 nM), and D-Ala2-D-Leu5-(/sup 3/H)enkephalin (KD . 5 nM) remaining after treating tissue with naloxazone demonstrates unique pharmacological profiles for each. These results suggest the existence of distinct binding sites for kappa- and sigma-opiates which differ from those sites which selectively bind morphine (mu) and enkephalin (delta).
Comparative Analysis between Lean, Six Sigma and Lean Six Sigma Concepts
Directory of Open Access Journals (Sweden)
Alexandra Mirela Cristina MUNTEANU
2017-06-01
Full Text Available This paper analyzes the benefits of Lean Six Sigma in comparison with Lean and Six Sigma, traditional improvement methodologies. The introduction highlights the appearance of Lean Six Sigma, early 2000s, as well as the benefits brought by the integrated approach. The following parts of the study emphasize the main differences between methodologies and their commonalities based on their synergy. Finally the advantages of Lean Six Sigma versus Lean and Six Sigma are analyzed and systematized by author in order to reveal Lean Six Sigma’s benefits.
THE LEAN AND SIX SIGMA SINERGY
Directory of Open Access Journals (Sweden)
Mirko Sokovic
2008-12-01
Full Text Available Many organizations, dealing with continuous improvement methods, have realized that Lean and Six Sigma methodologies complement each other. Lean manufacturing focuses on the remova l of waste so that all processes in the total system add value from the customers' perspectives. The main emphasis of Six Sigma is the application of statistical tools in a disciplined manner, which requires data-driven decision-making. The integration of Lean and Six Sigma provides a synergetic effect, a rapid process improvement strategy for attaining organizational goals. When separated, Lean manufacturing cannot bring a process under statistical control, and Six Sigma cannot dramatically improve cycle time or reduce invested capital. Together, synergistic qualities are created to maximize the potential for a process improvement. The paper deals with Lean and Six Sigma principles and approaches used in modern manufacturing for process improvements, and bring forward benefits that are gained when these two methodologies are integrated.
Production of Sigma{\\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy
Agakishiev, G; Belver, D; Belyaev, A; Berger-Chen, J C; Blanco, A; Boehmer, M; Boyard, J L; Cabanelas, P; Castro, E; Chernenko, S; Destefanis, T Christ M; Dohrmann, F; Dybczak, A; Epple, E; Fabbietti, L; Fateev, O; Finocchiaro, P; Fonte, P; Friese, J; Fröhlich, I; Galatyuk, T; Garzon, J A; Gernhäuser, R; Gilardi, C; Golubeva, M; Gonza'lez-Di'az, D; Guber, F; Gumberidze, M; Heinz, T; Hennino, T; Holzmann, R; Ierusalimov, A; Iori, I; Ivashkin, A; Jurkovic, M; Kämpfer, B; Kanaki, K; Karavicheva, T; Koenig, I; Koenig, W; Kolb, B W; Kotte, R; Kr'asa, A; Krizek, F; Krücken, R; Kuc, H; Kuehn, W; Kugler, A; Kurepin, A; Lalik, R; Lang, S; Lange, J S; Lapidus, K; Liu, T; Lopes, L; Lorenz, M; Maier, L; Mangiarotti, A; Markert, J; Metag, V; Michalska, B; Michel, J; Morinie're, E; Mousa, J; Müntz, C; Naumann, L; Otwinowski, J; Pachmayer, Y C; Palka, M; Parpottas, Y; Pechenov, V; Pechenova, O; Pietraszko, J; Przygoda, W; Ramstein, B; Reshetin, A; Rustamov, A; Sadovsky, A; Salabura, P; Schmah, A; Schwab, E; Siebenson, J; Sobolev, Yu G; Spataro, S; Spruck, B; Ströbele, H; Stroth, J; Sturm, C; Tarantola, A; Teilab, K; Tlusty, P; Traxler, M; Trebacz, R; Tsertos, H; Wagner, V; Weber, M; Wendisch, C; Wüstenfeld, J; Yurevich, S; Zanevsky, Y
2012-01-01
We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES experiment at GSI. This report evaluates the contribution of resonances like Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to the experimental data in several angular distributions and it shows itself as suitable to evaluate the acceptance corrections properly.
Leitnaker, James M.
1981-01-01
Austenitic stainless steel alloys containing delta ferrite, such as are used as weld deposits, are protected against the transformation of delta ferrite to sigma phase during aging by the presence of carbon plus nitrogen in a weight percent 0.015-0.030 times the volume percent ferrite present in the alloy. The formation of chi phase upon aging is controlled by controlling the Mo content.
Boyault, S; Simonin, M A; Bianchi, A; Compe, E; Liagre, B; Mainard, D; Bécuwe, P; Dauça, M; Netter, P; Terlain, B; Bordji, K
2001-07-13
The activation of peroxisome proliferator-activated receptor gamma (PPARgamma) has been shown to inhibit the production and the effects of proinflammatory cytokines. Since interleukin-1beta (IL-1beta) directly mediates cartilage degradation in osteoarthritis, we investigated the capability of PPARgamma ligands to modulate IL-1beta effects on human chondrocytes. RT-PCR and Western blot analysis revealed that PPARgamma expression was decreased by IL-1beta. 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2), in contrast to troglitazone, was highly potent to counteract IL-1beta-induced cyclooxygenase-2 and inductible nitric oxide synthase expression, NO production and the decrease in proteoglycan synthesis. Western blot and gel-shift analyses demonstrated that 15d-PGJ2 inhibited NF-kappaB activation, while troglitazone was ineffective. Although 15d-PGJ2 attenuated activator protein-1 binding on the DNA, it potentiated c-jun migration in the nucleus. The absence or the low effect of troglitazone suggests that 15d-PGJ2 action in human chondrocytes is mainly PPARgamma-independent.
Energy Technology Data Exchange (ETDEWEB)
Mahon, Jose Roberto Pinheiro
1993-12-31
We have measured the branching ratio of the radiative decay of the hyperon {Sigma}{sup -}. This experiment (E761) was performed with a 375 GeV/c charged hyperon beam in the Proton Center at Fermi National Accelerator Laboratory in Batavia, Illinois. We found a value for the branching ratio BR({Sigma}{sup -} -> p{gamma}) = (1,079 {+-} 0,230) x 10{sup -3} where the first error is statistical and the second is systematic. This result is based on a sample of 213 {+-} 19 events. We have also measured the {delta} parameter for a test of CP violation in hyperon decays. This result is consistent with CP invariance. (author) 79 refs., 42 figs., 13 tabs.
Proto-neutron stars with delta-resonances using the Zimanyi-Moszkowski model
Energy Technology Data Exchange (ETDEWEB)
Gomes, Luzinete Vilanova da Silva [Secretaria de Educacao, Cultura e Desportos do Estado de Roraima (SECD), RR (Brazil); Oliveira, Jose Carlos Teixeira de [Centro Federal de Educacao Tecnologica (CEFET-RJ), Rio de Janeiro, RJ (Brazil); Duarte, Sergio Barbosa [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
2011-07-01
Full text: In the present work we obtained the equation of state to be used to study the structure of proto-neutron stars. To this end, we adopted the model of Zimanyi-Moszkowski in the mean field approximation. In this model the equation of state consists of the octet of baryons of spin 1/2 (n, p, {Lambda}{sup 0}, {Sigma}{sup -}, {Sigma}{sup 0}, {Sigma}{sup +}, {Xi}{sup -}, {Xi}{sup 0}) and of the baryonic resonances of spin 3/2, represented by the delta matter ({Delta}{sup -}, {Delta}{sup 0}, {Delta}{sup +}, {Delta}{sup +}+ and by {Omega}{sup -}, in the baryonic sector. In the leptonic sector we consider the electrons, the muons and the trapped neutrinos. Thus, we studied the effects of the corresponding neutrinos on the equation of state during the initial formation of a neutron star. We discuss the structure of the proto-neutron stars including the delta resonances in their composition, and compared the results at the cooling phase induced by escape of neutrinos. From the equation of state obtained with this model we solve numerically the equation TOV (Tolman-Oppenheimer-Volkoff) and so we obtained the values of the maximum mass, before and after cooling. (author)
SIGMA WEB INTERFACE FOR REACTOR DATA APPLICATIONS
Energy Technology Data Exchange (ETDEWEB)
Pritychenko,B.; Sonzogni, A.A.
2010-05-09
We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma.
The biHermitian topological sigma model
Energy Technology Data Exchange (ETDEWEB)
Zucchini, Roberto [Dipartimento di Fisica, Universita degli Studi di Bologna, V. Irnerio 46, I-40126 Bologna (Italy); I.N.F.N., sezione di Bologna (Italy)
2006-12-15
BiHermitian geometry, discovered long ago by Gates, Hull and Rocek, is the most general sigma model target space geometry allowing for (2,2) world sheet supersymmetry. By using the twisting procedure proposed by Kapustin and Li, we work out the type A and B topological sigma models for a general biHermtian target space, we write down the explicit expression of the sigma model's action and BRST transformations and present a computation of the topological gauge fermion and the topological action.
Higher-Dimensional Geometric $\\sigma$-Models
Vasilic, M
1999-01-01
Geometric $\\sigma$-models have been defined as purely geometric theories of scalar fields coupled to gravity. By construction, these theories possess arbitrarily chosen vacuum solutions. Using this fact, one can build a Kaluza--Klein geometric $\\sigma$-model by specifying the vacuum metric of the form $M^4\\times B^d$. The obtained higher dimensional theory has vanishing cosmological constant but fails to give massless gauge fields after the dimensional reduction. In this paper, a modified geometric $\\sigma$-model is suggested, which solves the above problem.
Measurement of Natural Widths of Sigma-c-0 and Sigma-c-++ Baryons
Link, J M; Reyes, M; Yager, P M; Anjos, J C; Bediaga, I; Göbel, C; Magnin, J; Massafferri, A; De Miranda, J M; Pepe, I M; Dos Reis, A C; Carrillo, S; Casimiro, E; Cuautle, E; Sánchez-Hernández, A; Uribe, C; Vázquez, F; Agostino, L; Cinquini, L; Cumalat, J P; O'Reilly, B; Ramírez, J E; Segoni, I; Butler, J N; Cheung, H W K; Chiodini, G; Gaines, I; Garbincius, P H; Garren, L A; Gottschalk, E; Kasper, P H; Kreymer, A E; Kutschke, R; Bianco, S; Fabbri, Franco Luigi; Zallo, A; Cawlfield, C; Kim, D Y; Rahimi, A; Wiss, J; Gardner, R; Kryemadhi, A; Chung, Y S; Kang, J S; Ko, B R; Kwak, J W; Lee, K B; Park, H; Alimonti, G; Barberis, S; Boschini, M; D'Angelo, P; Di Corato, M; Dini, P; Edera, L; Erba, S; Giammarchi, M; Inzani, P; Leveraro, F; Malvezzi, S; Menasce, D; Mezzadri, M; Milazzo, L; Moroni, L; Pedrini, D; Pontoglio, C; Prelz, F; Rovere, M; Sala, S; Davenport, T F; Arena, V; Boca, G; Bonomi, G; Gianini, G; Liguori, G; Merlo, M M; Pantea, D; Ratti, S P; Riccardi, C; Vitulo, P; Hernández, H; López, A M; Méndez, H; Méndez, L; Montiel, E; Olaya, D; Paris, A; Quinones, J; Rivera, C; Xiong, W; Zhang, Y; Wilson, J R; Cho, K; Handler, T; Mitchell, R; Engh, D; Hosack, M; Johns, W E; Nehring, M; Sheldon, P D; Stenson, K; Vaandering, E W; Webster, M; Sheaff, M
2002-01-01
In this paper we present a measurement of the natural widths of $\\Sigma_c^0$ and $\\Sigma_c^{++}$. Using data from the FOCUS experiment, we find $\\Gamma(\\Sigma_c^0) = 1.55 +0.41/-0.37 \\pm 0.38$ MeV/c^2 and $\\Gamma(\\Sigma_c^0) = 2.05 +0.41/-0.38 \\pm 0.38$ MeV/c^2. The first errors are statistical, the second systematic. These results are obtained with a sample of 913 $\\Sigma_c^0 \\to \\Lambda_c^+ \\pi^-$ decays and 1110 $\\Sigma_c^++ \\to \\Lambda_c^+ \\pi^+$ decays. These results are compared with recent theoretical predictions. PACS numbers: 14.20.Lq 13.30Eg
Measurements of the $\\Sigma_{c}^{0}$ and $\\Sigma_{c}^{++}$ Mass Splittings
Link, J M; Reyes, M; Yager, P M; Anjos, J C; Bediaga, I; Göbel, C; Magnin, J; De Miranda, J M; Pepe, I M; Dos Reis, A C; Simão, F R A; Carrillo, S; Casimiro, E; Méndez, H; Sánchez-Hernández, A; Uribe, C; Vázquez, F; Cinquini, L; Cumalat, J P; Ramírez, J E; O'Reilly, B; Vaandering, E W; Butler, J N; Cheung, H W K; Gaines, I; Garbincius, P H; Garren, L A; Gottschalk, E E; Gourlay, S A; Kasper, P H; Kreymer, A E; Kutschke, R; Bianco, S; Fabbri, Franco Luigi; Sarwar, S; Zallo, A; Cawlfield, C; Kim, D Y; Park, K S; Rahimi, A; Wiss, J; Gardner, R; Chung, Y S; Kang, J S; Ko, B R; Kwak, J W; Lee, K B; Myung, S S; Park, H; Alimonti, G; Boschini, M; Brambilla, D; Caccianiga, B; Calandrino, A; D'Angelo, P; Di Corato, M; Dini, P; Giammarchi, M G; Inzani, P; Leveraro, F; Malvezzi, S; Menasce, D; Mezzadri, M; Milazzo, L; Moroni, L; Pedrini, D; Prelz, F; Rovere, M; Sala, A; Sala, S; Davenport, T F; Arena, V; Boca, G; Bonomi, G; Gianini, G; Liguori, G; Merlo, M; Pantea, D; Ratti, S P; Riccardi, C; Torre, P; Viola, L; Vitulo, P; Hernández, H; López, A M; Méndez, L; Mirles, M A; Montiel, E; Olaya, D; Quinones, J; Rivera, C; Zhang, Y; Copty, N K; Purohit, M; Wilson, J R; Cho, K; Handler, T; Engh, D; Johns, W E; Hosack, M; Nehring, M S; Sales, M; Sheldon, P D; Stenson, K; Webster, M S; Sheaff, M; Kwon, Y J
2000-01-01
Using a high statistics sample of photoproduced charmed particles from the FOCUS experiment at Fermilab (FNAL-E831), we measure the mass splittings of the charmed baryons Sigma_c^0 and Sigma_c^{++}. We find M(Sigma_c^0 - Lambda_c^+) = 167.38 +/- 0.21 +/- 0.13 MeV/c^2 and M(Sigma_c^++ - Lambda_c^+) = 167.35 +/- 0.19 +/- 0.12 MeV/c^2 with samples of 362 +/- 36 and 461 +/- 39 events, respectively. We measure the isospin mass splitting M(Sigma_c^++ - Sigma_c^0) to be -0.03 +/- 0.28 +/- 0.11 Mev/c^2. The first errors are statistical and the second are systematic.
Pion-Nucleon Scattering in a Large-N Sigma Model
Mattis, M P; MATTIS, Michael P.; SILBAR, Richard R.
1995-01-01
We review the large-N_c approach to meson-baryon scattering, including recent interesting developments. We then study pion-nucleon scattering in a particular variant of the linear sigma-model, in which the couplings of the sigma and pi mesons to the nucleon are echoed by couplings to the entire tower of I=J baryons (including the Delta) as dictated by large-N_c group theory. We sum the complete set of multi-loop meson-exchange \\pi N --> \\pi N and \\pi N --> \\sigma N Feynman diagrams, to leading order in 1/N_c. The key idea, reviewed in detail, is that large-N_c allows the approximation of LOOP graphs by TREE graphs, so long as the loops contain at least one baryon leg; trees, in turn, can be summed by solving classical equations of motion. We exhibit the resulting partial-wave S-matrix and the rich nucleon and Delta resonance spectrum of this simple model, comparing not only to experiment but also to pion-nucleon scattering in the Skyrme model. The moral is that much of the detailed structure of the meson-bary...
Six Sigma: not for the faint of heart.
Benedetto, Anthony R
2003-01-01
higher-level institutional leaders. This document should address the specific outcomes desired, the resources available, a rough tentative timeline, and any political constraints imposed on the project (e.g., inviolate HR policies, compatibility with enterprise strategic goals). The document should be comprehensive enough and explicit enough to be useful as a major component of the bid package for hiring a consultant or for writing the job description for the hiring of an in-house expert. A full-time project manager should be designated if an in-house expert is not hired. This person should be a senior leader in the department, but not the department director. Leading a Six Sigma project is a full-time job in itself and cannot be performed as an additional duty. Although it may be tempting to appoint a senior staff technologist or nurse, keep in mind that the project manager must have sufficient authority to expect cooperation from departmental supervisors without resorting to frequent appeals to the department director. Contact the institution's CIO and ask that a knowledgeable person on the IT staff be appointed to serve as the IT liaison for the project. This person should have in-depth familiarity with the HIS and the ways that it interfaces with the RIS (if the RIS is not a module within the HIS). Most importantly, this liaison must understand the exact data definitions and the origins of the data that are passed between the HIS and the RIS. The steering committee should consist of at least one physician and one department-level administrator from outside of the radiology department. From within the radiology department, there should be at least one radiologist and one senior modality manager (whose modality is not the primary focus), the project manager, and the manager of a radiology component that is a focus of the project (e.g., the film library manager). The consultant should be an ex officio member without vote. The steering committee should be small enough to
IDENTIFICATION AND SELECTION OF SIX SIGMA PROJECTS
Directory of Open Access Journals (Sweden)
Abdalhkeim FA. Flifel
2017-04-01
Full Text Available Six Sigma is a well-structured and proven methodology for improving organizational performance. It helps achieving the goals of the organization through the use of project-driven approach. The implementation of Six sigma approach depends on proper identification and selection of projects, moreover, the selection of right Six sigma projects is one of the critical success factors of six sigma efforts. The paper provides the sources for the identification of potential projects, top down and bottom up approaches, the process of selection of projects, guidelines that assist the selection of appropriate projects, selection criteria which must be precisely chosen in accordance with the objectives, needs and capabilities of the organization as well as sophisticated techniques and tools recommended in the literature for the selection of projects.
Operation of six sigma in production engineering
Directory of Open Access Journals (Sweden)
Eduardo José Pereira Martin
2016-03-01
Full Text Available In an increasingly competitive world, where deadlines and targets are becoming more narrow and difficult to achieve, organizations are seeking new competitive advantages that allow them to improve their development, and it is in this context that the Six Sigma program offers a way to enable such income. This study consists of a literature review on the topic: Six Sigma; and a bibliometric review in order to identify the use of the Six Sigma program in Production Engineering. The database ABEPRO was used for the research, which resulted in a set of 34 publications that identified the main centers of studies, authors and more universities that have published articles on the subject, the most recurrent keywords used, number of publications per year, the type of research presented and the tools used in conjunction with the Six Sigma program. Through analysis of the selected articles, it was possible to answer such questions as those asked above
Regulation of alternative sigma factor use.
Österberg, Sofia; del Peso-Santos, Teresa; Shingler, Victoria
2011-01-01
Alternative bacterial sigma factors bind the catalytic core RNA polymerase to confer promoter selectivity on the holoenzyme. The different holoenzymes are thus programmed to recognize the distinct promoter classes in the genome to allow coordinated activation of discrete sets of genes needed for adaptive responses. To form the holoenzymes, the different sigma factors must be available to compete for their common substrate (core RNA polymerase). This review highlights (a) the roles of antisigma factors in controlling the availability of alternative sigma factors and (b) the involvement of diverse regulatory molecules that promote the use of alternative sigma factors through subversion of the domineering housekeeping σ(70). The latter include the nucleotide alarmone ppGpp and small proteins (DksA, Rsd, and Crl), which directly target the transcriptional machinery to mediate their effects.
Lean six sigma application to transportation logistics
Directory of Open Access Journals (Sweden)
Simone Tavares Fernandes
2012-06-01
Full Text Available This work presents the application of Lean Six Sigma in a case study of a metallurgic industry. The Six Sigma and the Lean are two processes used by enterprises in Brazil and worldwide. Currently the integration of these processes is a challenge for these companies, which search a way more efficient to reduce their wastes and to adapt to the needs of their markets. The paper had as purpose to demonstrate the applicability of the Lean Six Sigma in a real logistical problem related to the transportation of goods among units of a metallurgic industry. The stages used for the solution of the problem follow the DMAIC cycle – Define, Measure, Analyze, Improve and Control. The paper presents in details the integrated approach of the improvement processes Lean and Six Sigma, their tools set, as well the excellent results obtained in the case study.
Properties of sigma and kappa Production Amplitudes
Ishida, M; Ishida, Muneyuki; Ishida, Shin
2003-01-01
Our method of analysis, which led to existence of sigma and kappa mesons, is reviewed and examined from a viewpoint of general S-matrix. It is shown that the method is consistent with the constraints from chiral symmetry and unitarity. Accordingly the long-believed common analyses of pipi (Kpi) scattering and production processes, based on elastic unitarity, prove to lose its theoretical base. The observed phase motion by 180 degrees of sigma shows also the validity of our method.
Generalized Kahler Geometry from supersymmetric sigma models
Bredthauer, A; Persson, J; Zabzine, M; Bredthauer, Andreas; Lindstrom, Ulf; Persson, Jonas; Zabzine, Maxim
2006-01-01
We give a physical derivation of generalized Kahler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri regarding the equivalence between generalized Kahler geometry and the bi-hermitean geometry of Gates-Hull-Rocek. When cast in the language of supersymmetric sigma models, this relation maps precisely to that between the Lagrangian and the Hamiltonian formalisms. We also discuss topological twist in this context.
Rudder-roll stabilization using fgs-pid controller for sigma-e warship
Santoso, M. Y.; Munadhif, I.; Wahidin, A.; Ruddianto; Fathulloh; Soelistijono, R. T.
2017-06-01
The aim of rudder-roll stabilization (RSS) is controlling ship heading and reducing roll motion simultaneously using one actuator, rudder. In this paper, RSS using FGS-PID for SIGMA-e warship was performed, both in normal and disturbed sea conditions. The fuzzy system for determining PID controller are constructed from SIGMA-e linear mathematical model. The wave disturbances are generated based on the WMO. The results show that FGS-PID has superior performance compared to conventional PID controller in heading control and roll damping. It means that the proposed control method can encounter the environmental changes.
Bacterial Sigma Factors and Anti-Sigma Factors: Structure, Function and Distribution
Directory of Open Access Journals (Sweden)
Mark S. Paget
2015-06-01
Full Text Available Sigma factors are multi-domain subunits of bacterial RNA polymerase (RNAP that play critical roles in transcription initiation, including the recognition and opening of promoters as well as the initial steps in RNA synthesis. This review focuses on the structure and function of the major sigma-70 class that includes the housekeeping sigma factor (Group 1 that directs the bulk of transcription during active growth, and structurally-related alternative sigma factors (Groups 2–4 that control a wide variety of adaptive responses such as morphological development and the management of stress. A recurring theme in sigma factor control is their sequestration by anti-sigma factors that occlude their RNAP-binding determinants. Sigma factors are then released through a wide variety of mechanisms, often involving branched signal transduction pathways that allow the integration of distinct signals. Three major strategies for sigma release are discussed: regulated proteolysis, partner-switching, and direct sensing by the anti-sigma factor.
Delta hedging strategies comparison
DEFF Research Database (Denmark)
De Giovanni, Domenico; Ortobelli, S.; Rachev, S.T.
2008-01-01
In this paper we implement dynamic delta hedging strategies based on several option pricing models. We analyze different subordinated option pricing models and we examine delta hedging costs using ex-post daily prices of S&P 500. Furthermore, we compare the performance of each subordinated model ...
Regulation of antimicrobial resistance by extracytoplasmic function (ECF) sigma factors.
Woods, Emily C; McBride, Shonna M
2017-01-30
Extracytoplasmic function (ECF) sigma factors are a subfamily of σ(70) sigma factors that activate genes involved in stress-response functions. In many bacteria, ECF sigma factors regulate resistance to antimicrobial compounds. This review will summarize the ECF sigma factors that regulate antimicrobial resistance in model organisms and clinically relevant pathogens.
The Oscillator Strengths of H2+, 1s\\sigma_{g}-2p\\sigma_{u}, 1s\\sigma_{g}-2p\\pi_{u}
Tsogbayar, Ts
2010-01-01
The oscillator strengths of the $H^+_2$ molecular ion, $1s\\sigma_{g}-2p\\sigma_{u}$, $1s\\sigma_{g}-2p\\pi_{u}$ are calculated within the Born-Oppenheimer approximation. The variational expansion with randomly chosen exponents has been used for numerical studies. The oscillator strengths obtained for the transitions $1s\\sigma_{g}-2p\\sigma_{u}$, $1s\\sigma_{g}-2p\\pi_{u}$ of $H^+_2$ are accurate up to ten significant digits. Results are given for the internuclear distances between 0.10 and 20.0 a.u.
Babusci, D.; Balwierz-Pytko, I.; Bencivenni, G.; Bini, C.; Bloise, C.; Bossi, F.; Branchini, P.; Budano, A.; Caldeira Balkestahl, L.; Capon, G.; Ceradini, F.; Ciambrone, P.; Curciarello, F.; Czerwinski, E.; Dane, E.; De Leo, V.; De Lucia, E.; De Robertis, G.; De Santis, A.; De Simone, P.; Di Domenico, A.; Di Donato, C.; Domenici, D.; Erriquez, O.; Fanizzi, G.; Felici, G.; Fiore, S.; Franzini, P.; Gauzzi, P.; Giardina, G.; Giovannella, S.; Gonnella, F.; Graziani, E.; Happacher, F.; Heijkenskjold, L.; Hoistad, B.; Iafolla, L.; Iarocci, E.; Jacewicz, M.; Johansson, T.; Kluge, W.; Kupsc, A.; Lee-Franzini, J.; Loddo, F.; Lukin, P.; Mandaglio, G.; Martemianov, M.; Martini, M.; Mascolo, M.; Messi, R.; Miscetti, S.; Morello, G.; Moricciani, D.; Moskal, P.; Muller, S.; Nguyen, F.; Passeri, A.; Patera, V.; Prado Longhi, I.; Ranieri, A.; Redmer, C.F.; Santangelo, P.; Sarra, I.; Schioppa, M.; Sciascia, B.; Silarski, M.; Taccini, C.; Tortora, L.; Venanzoni, G.; Versaci, R.; Wislicki, W.; Wolke, M.; Zdebik, J.
2013-01-01
We have measured the ratio $\\sigma(e^+e^-\\rightarrow\\pi^+\\pi^-\\gamma)/\\sigma(e^+e^-\\rightarrow \\mu^+\\mu^-\\gamma)$, with the KLOE detector at DA$\\Phi$NE for a total integrated luminosity of $\\sim$ 240 pb$^{-1}$. From this ratio we obtain the cross section $\\sigma(e^+e^-\\rightarrow\\pi^+\\pi^-)$. From the cross section we determine the pion form factor $|F_\\pi|^2$ and the two-pion contribution to the muon anomaly $a_\\mu$ for $0.592
Horizontal Symmetries $\\Delta(150)$ and $\\Delta(600)$
Lam, C S
2013-01-01
Using group theory of mixing to examine all finite subgroups of SU(3) with an order less than 512, we found recently that only the group $\\Delta(150)$ can give rise to a correct reactor angle $\\th_{13}$ of neutrino mixing without any free parameter. It predicts $\\sin^22\\th_{13}=0.11$ and a sub-maximal atmospheric angle with $\\sin^22\\th_{23}=0.94$, in good agreement with experiment. The solar angle $\\th_{12}$, the CP phase $\\d$, and the neutrino masses $m_i$ are left as free parameters. In this article we provide more details of this case, discuss possible gain and loss by introducing right-handed symmetries, and/or valons to construct dynamical models. A simple model is discussed where the solar angle agrees with experiment, and all its mixing parameters can be obtained from the group $\\Delta(600)$ by symmetry alone. The promotion of $\\Delta(150)$ to $\\Delta(600)$ is on the one hand analogous to the promotion of $S_3$ to $S_4$ in the presence of tribimaximal mixing, and on the other hand similar to the extens...
Yamanaka, Nodoka
2016-01-01
We calculate the electric dipole moment (EDM) of the deuteron in the standard model with $|\\Delta S| =1$ interactions by taking into account the $NN - \\Lambda N - \\Sigma N$ channel coupling. The two-body problem is solved with the Gaussian Expansion Method using the realistic Argonne $v18$ nuclear force and the $YN$ potential which can reproduce the binding energies of $^3_\\Lambda$H, $^3_\\Lambda$He, and $^4_\\Lambda$He. The $|\\Delta S| =1$ interbaryon potential is modeled by the one-meson exchange process. It is found that the deuteron EDM is modified by less than 10\\%, and the main contribution to this deviation is due to the polarization of the hyperon-nucleon channels. The effect of the $YN$ interaction is small, and treating $ \\Lambda N$ and $ \\Sigma N$ channels as free is a good approximation for the EDM of the deuteron.
Six sigma quality for fuel manufacturing
Energy Technology Data Exchange (ETDEWEB)
Gabbani, M.D.; Onderwater, T. [GE Canada, Fuel Manufacturing Plant, Peterborough, Ontario (Canada)
1997-07-01
It is widely recognized that operational performance in product manufacturing is largely determined by understanding and maintaining process capability. By definition, Six Sigma is a statistical unit of measure reflecting process capability that yields less' than 6.8 defects per million product produced. Statistically, this translates into obtaining a long term manufacturing process capability of {+-} 4.5 standard deviations aboutthe mean within specification limits. The heart of the Six Sigma program developed by the Six Sigma Academy is what we refer to as the Breakthrough Strategy. This rigorous analytical methodology is the driving force in obtaining world class performance of Six Sigma. The methodology applies statistical and practical tools in resolving a problem or improving a product or process. The application of Six Sigma focuses on attacking process input variables (independent) rather than the output variables. Focusing on these independent variables (temperature, power, force, etc.) and the variation in the end product they create, enables us to get to the root of the problem rather than react to the symptoms of the problem. In this manner we prevent defects from occurring rather than inspecting and monitoring the product. Why the need for such an ambitious program? It is estimated that the cost of failure (rework, scrap, warranties, etc.) can be as high as 15% of sales for companies typically operating at 3-4 sigma. In achieving Six Sigma, costs of failure are typically less than 5%. The thought of reducing business costs while achieving the recognition of being our customer's premier choice provides enormous incentive to reach such status. (author)
Isobar Model for Photoproduction of K+Sigma0 and K0Sigma+ on the Proton
Mart, T
2005-01-01
Kaon photoproductions on the proton gamma p --> K+Sigma0 and gamma p --> K0Sigma+ have been simultaneously analyzed by using isobar models and new SAPHIR data. The result shows that isobar models such as KAON MAID require more resonances in order to explain the data.
Cosmic Evolution of Black Holes And Spheroids. 1, the M(BH)-Sigma Relation at Z=0.36
Energy Technology Data Exchange (ETDEWEB)
Woo, Jong-Hak; Treu, Tommaso; /UC, Santa Barbara; Malkan, Matthew A.; /UCLA; Blandford, Roger D.; /KIPAC, Menlo Park
2006-04-17
We test the evolution of the correlation between black hole mass and bulge velocity dispersion (M{sub BH} - {sigma}), using a carefully selected sample of 14 Seyfert 1 galaxies at z = 0.36 {+-} 0.01. We measure velocity dispersion from stellar absorption lines around Mgb (5175 {angstrom}) and Fe (5270 {angstrom}) using high S/N Keck spectra, and estimate black hole mass from the H{beta} line width and the optical luminosity at 5100 {angstrom}, based on the empirically calibrated photo-ionization method. We find a significant offset from the local relation, in the sense that velocity dispersions were smaller for given black hole masses at z = 0.36 than locally. We investigate various sources of systematic uncertainties and find that those cannot account for the observed offset. The measured offset is {Delta} log M{sub BH} = 0.62 {+-} 0.10 {+-} 0.25, i.e. {Delta} log {sigma} = 0.15 {+-} 0.03 {+-} 0.06, where the error bars include a random component and an upper limit to the systematics. At face value, this result implies a substantial growth of bulges in the last 4 Gyr, assuming that the local M{sub BH} - {sigma} relation is the universal evolutionary end-point. Along with two samples of active galaxies with consistently determined black hole mass and stellar velocity dispersion taken from the literature, we quantify the observed evolution with the best fit linear relation, {Delta} log M{sub BH} = (1.66 {+-} 0.43)z + (0.04 {+-} 0.09) with respect to the local relationship of Tremaine et al. (2002), and {Delta} log M{sub BH} = (1.55 {+-} 0.46)z +(0.01 {+-} 0.12) with respect to that of Ferrarese (2002). This result is consistent with the growth of black holes predating the final growth of bulges at these mass scales (<{sigma}> = 170 km s{sup -1}).
Sigma-drop in galaxies and the sigma-metallicity degeneracy
Koleva, Mina; De Rijcke, Sven
2008-01-01
In some galaxies, the central velocity dispersion, sigma, is depressed with respect to the surroundings. This sigma-drop phenomenon may have different physical origins, bearing information about the internal dynamics of the host galaxy. In this article, we stress the importance also of observational artifacts due to the sigma-metallicity degeneracy: when a spectrum of a population is compared with a template of miss-matched metallicity, the velocity dispersion may be wrongly estimated. A sigma-drop may appear in place of a metallicity peak. The discussion is illustrated using VLT/FORS spectra of diffuse elliptical galaxies. Some of the sigma-drop galaxies reported in the literature may be analysis artifacts.
Glennon, Richard A.
2005-01-01
Sigma (sigma) receptors, once considered a type of opioid receptor, are now recognized as representing a unique receptive entity and at least two different types of sigma receptors have been identified: sigma1 and sigma2 receptors. Evidence suggests that these receptors might be targeted and exploited for the development of agents potentially useful for the treatment of several central disorders. This review primarily describes some of our efforts to understand those structural features that ...
On the width of N-Delta and Delta-Delta states
Niskanen, J A
2016-01-01
It is seen by a coupled-channel calculation that in the two-baryon N-Delta or Delta-Delta system the width of the state is greatly diminished due to the relative kinetic energy of the two baryons, since the internal energy of the particles, available for pionic decay, is smaller. A similar state dependent effect arises from the centrifugal barrier in N-Delta or Delta-Delta systems with non-zero orbital angular momentum. The double-Delta width can become even smaller than the free width of a single Delta. This has some bearing to the interpretation of the d'(2380) resonance recently discovered at COSY.
Six Lessons We Learned Applying Six Sigma
Carroll, Napoleon; Casleton, Christa H.
2005-01-01
As Chief Financial Officer of Kennedy Space Center (KSC), I'm not only responsible for financial planning and accounting but also for building strong partnerships with the CFO customers, who include Space Shuttle and International Space Station operations as well all who manage the KSC Spaceport. My never ending goal is to design, manage and continuously improve our core business processes so that they deliver world class products and services to the CFO's customers. I became interested in Six Sigma as Christa Casleton (KSC's first Six Sigma Black belt) applied Six Sigma tools and methods to our Plan and Account for Travel Costs Process. Her analysis was fresh, innovative and thorough but, even more impressive, was her approach to ensure ongoing, continuous process improvement. Encouraged by the results, I launched two more process improvement initiatives aimed at applying Six Sigma principles to CFO processes that not only touch most of my employees but also have direct customer impact. As many of you know, Six Sigma is a measurement scale that compares the output of a process with customer requirements. That's straight forward, but demands that you not only understand your processes but also know your products and the critical customer requirements. The objective is to isolate and eliminate the causes of process variation so that the customer sees consistently high quality.
Geometric sigma model of the Universe
Vasilić, Milovan
2017-05-01
The purpose of this work is to demonstrate how an arbitrarily chosen background of the Universe can be made a solution of a simple geometric sigma model. Geometric sigma models are purely geometric theories in which spacetime coordinates are seen as scalar fields coupled to gravity. Although they look like ordinary sigma models, they have the peculiarity that their complete matter content can be gauged away. The remaining geometric theory possesses a background solution that is predefined in the process of constructing the theory. The fact that background configuration is specified in advance is another peculiarity of geometric sigma models. In this paper, I construct geometric sigma models based on different background geometries of the Universe. Whatever background geometry is chosen, the dynamics of its small perturbations is shown to have a generic classical stability. This way, any freely chosen background metric is made a stable solution of a simple model. Three particular models of the Universe are considered as examples of how this is done in practice. Supported by Serbian Ministry of Education, Science and Technological Development (171031)
Santel, D; Chang, P; Abdesselam, A; Adachi, I; Aihara, H; Said, S Al; Arinstein, K; Asner, D M; Aushev, T; Ayad, R; Bakich, A M; Bansal, V; Bhuyan, B; Bobrov, A; Bondar, A; Bonvicini, G; Bračko, M; Browder, T E; Červenkov, D; Chekelian, V; Cheon, B G; Chilikin, K; Cho, K; Chobanova, V; Choi, S -K; Choi, Y; Cinabro, D; Dalseno, J; Danilov, M; Dingfelder, J; Doležal, Z; Drásal, Z; Drutskoy, A; Eidelman, S; Farhat, H; Fast, J E; Ferber, T; Gaur, V; Gabyshev, N; Garmash, A; Getzkow, D; Gillard, R; Goh, Y M; Haba, J; Hara, T; Hayasaka, K; Hayashii, H; He, X H; Hou, W -S; Hyun, H J; Iijima, T; Inami, K; Ishikawa, A; Itoh, R; Iwasaki, Y; Jaegle, I; Joffe, D; Julius, T; Kang, K H; Kato, E; Kawasaki, T; Kiesling, C; Kim, D Y; Kim, H J; Kim, J B; Kim, J H; Kim, M J; Kim, S H; Kim, Y J; Ko, B R; Kodyš, P; Korpar, S; Križan, P; Krokovny, P; Kuzmin, A; Lange, J S; Lee, I S; Li, Y; Gioi, L Li; Libby, J; Liventsev, D; Lukin, P; Matvienko, D; Miyabayashi, K; Miyata, H; Mizuk, R; Mohanty, G B; Moll, A; Mori, T; Mussa, R; Nakano, E; Nakao, M; Nanut, T; Natkaniec, Z; Nisar, N K; Nishida, S; Ogawa, S; Okuno, S; Olsen, S L; Oswald, C; Pakhlov, P; Pakhlova, G; Park, C W; Park, H; Pedlar, T K; Petrič, M; Piilonen, L E; Ribežl, E; Ritter, M; Rostomyan, A; Ryu, S; Sakai, Y; Sandilya, S; Santelj, L; Sanuki, T; Savinov, V; Schneider, O; Schnell, G; Schwanda, C; Schwartz, A J; Senyo, K; Sevior, M E; Shebalin, V; Shibata, T -A; Shiu, J -G; Shwartz, B; Sibidanov, A; Simon, F; Sohn, Y -S; Solovieva, E; Starič, M; Steder, M; Tamponi, U; Tatishvili, G; Teramoto, Y; Trabelsi, K; Uchida, M; Uglov, T; Unno, Y; Uno, S; Van Hulse, C; Vanhoefer, P; Varner, G; Vinokurova, A; Wagner, M N; Wang, P; Wang, X L; Watanabe, M; Watanabe, Y; Won, E; Yamaoka, J; Yang, Y -P; Yashchenko, S; Yook, Y; Yusa, Y; Zhang, Z P; Zhilich, V; Zhulanov, V; Zupanc, A
2016-01-01
We report new measurements of $R_{\\Upsilon\\pi\\pi}\\equiv\\sigma(e^+e^-\\to \\Upsilon(n{\\rm S})\\pi^+\\pi^-)/\\sigma^0_{\\mu\\mu}$ ($n$ = 1, 2, 3) and $R_b\\equiv\\sigma(e^+e^-\\to b\\bar b)/\\sigma^0_{\\mu\\mu}$ (where $\\sigma^0_{\\mu\\mu}$ is the muon-pair Born cross section) in the region $\\sqrt{s} = 10.63$-$11.05$ GeV, based on data collected with the Belle detector. Distributions in $R_{\\Upsilon\\pi\\pi}$ and $R_b$ are fit for the masses and widths of the $\\Upsilon(10860)$ and $\\Upsilon(11020)$ resonances. Unlike $R_b$, which includes a large non-resonant $b\\bar{b}$ component, we find that $R_{\\Upsilon\\pi\\pi}$ is dominated by the two resonances. With $R_{\\Upsilon\\pi\\pi}$ as the basis, the total rate at the $\\Upsilon(10860)$ peak for known final states containing bottomonium(-like) resonances is estimated. We find that $\\Upsilon(10860)$ is essentially saturated by such modes, raising doubts about the validity of masses measured using $R_b$. With $R_{\\Upsilon\\pi\\pi}$, we measure $M_{10860}=(10891.1\\pm3.2^{+0.6}_{-1.5})$ MeV/$c...
Karmazyn-Campelli, Céline; Rhayat, Lamya; Carballido-López, Rut; Duperrier, Sandra; Frandsen, Niels; Stragier, Patrick
2008-03-01
Sporulation in Bacillus subtilis is a primitive differentiation process involving two cell types, the forespore and the mother cell. Each cell implements two successive transcription programmes controlled by specific sigma factors. We report that activity of sigma(G), the late forespore sigma factor, is kept in check by Gin, the product of csfB, a gene controlled by sigma(F), the early forespore sigma factor. Gin abolishes sigma(G) transcriptional activity when sigma(G) is artificially synthesized during growth, but has no effect on sigma(F). Gin interacts strongly with sigma(G) but not with sigma(F) in a yeast two-hybrid experiment. The absence of Gin allows sigma(G) to be active during sporulation independently of the mother-cell development to which it is normally coupled. Premature sigma(G) activity leads to the formation of slow-germinating spores, and complete deregulation of sigma(G) synthesis is lethal when combined with gin inactivation. Gin allows sigma(F) to delay the switch to the late forespore transcription programme by preventing sigma(G) to take over before the cell has reached a critical stage of development. A similar strategy, following a completely unrelated route, is used by the mother cell.
Observation and calculation of the Cs2 2 3Delta(1g) and b 3Pi(0u) states.
Xie, Feng; Li, Dan; Tyree, Luke; Li, Li; Sovkov, Vladimir B; Ivanov, Valery S; Magnier, Sylvie; Marjatta Lyyra, A
2008-05-28
The Cs(2) 2 (3)Delta(1g) and b (3)Pi(0u) states have been observed by infrared-infrared double resonance spectroscopy for the first time. 221 2 (3)Delta(1g)<--A (1)Sigma(u) (+)<--X (1)Sigma(g) (+) double resonance lines have been assigned to transitions into the 2 (3)Delta(1g) v=6-13 vibrational levels. Resolved fluorescence into the b (3)Pi(0u) v(')=0-48 levels has been recorded. Molecular constants and potential energy curves are determined by the global fit of the entire set of the experimental data. Theoretical potential energy curves of the 2 (3)Delta(g) and b (3)Pi(u) states have been determined in the framework of the pseudopotential method and are compared with the experimental results.
California Department of Resources — Surficial geology of the Delta area of California by Brian Atwater of the U.S. Geological Survey. Source maps are from the USGS publication MF-1401. This digital...
Six Sigma Driven Enterprise Model Transformation
Directory of Open Access Journals (Sweden)
Raymond Vella
2009-10-01
Full Text Available Enterprise architecture methods provide a structured system to understand enterprise activities. However, existing enterprise modelling methodologies take static views of the enterprise and do not naturally lead to a path of improvement during enterprise model transformation. This paper discusses the need for a methodology to facilitate changes for improvement in an enterprise. The six sigma methodology is proposed as the tool to facilitate progressive and continual Enterprise Model Transformation to allow businesses to adapt to meet increased customer expectation and global competition. An alignment of six sigma with phases of GERAM life cycle is described with inclusion of Critical-To-Satisfaction (CTS requirements. The synergies of combining the two methodologies are presented in an effort to provide a more culturally embedded framework for Enterprise Model Transformation that builds on the success of six sigma.
Disc instantons in linear sigma models
Energy Technology Data Exchange (ETDEWEB)
Govindarajan, Suresh E-mail: suresh@chaos.iitm.ernet.in; Jayaraman, T. E-mail: jayaram@imsc.ernet.in; Sarkar, Tapobrata E-mail: tapo@theory.tifr.res.in
2002-12-16
We construct a linear sigma model for open-strings ending on special Lagrangian cycles of a Calabi-Yau manifold. We illustrate the construction for the cases considered by Aganagic and Vafa (AV). This leads naturally to concrete models for the moduli space of open-string instantons. These instanton moduli spaces can be seen to be intimately related to certain auxiliary boundary toric varieties. By considering the relevant Gelfand-Kapranov-Zelevinsky (GKZ) differential equations of the boundary toric variety, we obtain the contributions to the world volume superpotential on the A-branes from open-string instantons. By using an ansatz due to Aganagic, Klemm and Vafa (AKV), we obtain the relevant change of variables from the linear sigma model to the non-linear sigma model variables--the open-string mirror map. Using this mirror map, we obtain results in agreement with those of AV and AKV for the counting of holomorphic disc instantons.
Eugster, P.; Guerraoui, R.; Kouznetsov, P.
2001-01-01
This paper presents a new, non-binary measure of the reliability of broadcast algorithms, called Delta-Reliability. This measure quantifies the reliability of practical broadcast algorithms that, on the one hand, were devised with some form of reliability in mind, but, on the other hand, are not considered reliable according to the ``traditional'' notion of broadcast reliability [HT94]. Our specification of Delta-Reliability suggests a further step towards bridging the gap between theory and...
Optimization of Coaching Using Six Sigma
Directory of Open Access Journals (Sweden)
Dumitru Colibaba-Evulet
2011-01-01
Full Text Available Problem statement: In todays sports world, coaching and training methods are the subject of intensive competition amongst rivals. Innovative technologies, methodologies and preparation methods are employed to achieve a sustainable competitive advantage. Effective performance measurement, statistical analysis and data based decision taking have been identified as key elements towards efficient performance management. The statistical approach has been emphasized in order to fill the gaps in athletes preparation and improve performance. There is need to better connect the dots between the methods of statistical analysis and training and coaching methods used to improve the performance of an athlete or a team. Approach: Industry giants such as Motorola, General Electric and other improved the quality of their products through a statistically driven, six sigma methodology. Literatures in the six sigma performance measurement and improvement in industry, as well as traditional coaching in sports had been extensively reviewed. Research was carried out to establish potential application of six sigma in performance measurement and improvement in sports. Results: The six sigma approach was identified as a new method in measuring, analyzing, improving and analyzing sports performance and two examples were given. The methodology was applied on one example of data collected by authors over years of performance of a basketball team. Direction for further studies in the application of six sigma methodology in team and individual performance coaching and management were also identified. Conclusion: The results of this study determined that there is significant potential to successfully introduce the six sigma methodology of measurement, analysis and improvement in athletic performance. This new direction of analysis involved augmenting the existing traditional methods of coaching and performance management with a powerful methodology
SIX SIGMA - A NEW APPROACH OF QUALITY
Directory of Open Access Journals (Sweden)
Maria Nicolai, Sofia Totolici
2005-01-01
Full Text Available The term six sigma was elaborated by Motorola Corp, in the early ‘80s, after a visit in Japan. The method’s application with this name has reduced the fabrication deficiencies with 99,7%, thus, in 1998, Motorola Corp. was one of the first companies to receive The Quality National Award in USA,“Malcolm Baldrige”. Then the method was used by other companies as well, which have declared that using the six sigma method, the 3,4 deficiencies per million of opportunities level may beachieved, attaining not perfection, but almost perfection.
A Lean Six Sigma journey in radiology.
Bucci, Ronald V; Musitano, Anne
2011-01-01
The department of radiology at Akron Children's Hospital embarked on a Lean Six Sigma mission as part of a hospital wide initiative to show increased customer satisfaction, reduce employee dissatisfaction and frustration, and decrease costs. Three processes that were addressed were reducing the MRI scheduling back-log, reconciling discrepancies in billing radiology procedures, and implementing a daily management system. Keys to success is that managers provide opportunities to openly communicate between department sections to break down barriers. Executive leaders must be engaged in Lean Six Sigma for the company to be successful.
$K^0$-$\\Sigma^+$ Photoproduction with SAPHIR
Bennhold, C
1998-01-01
Preliminary results of the analysis of the reaction p(gamma,K0)Sigma+ are presented. We show the first measurement of the differential cross section and much improved data for the total cross section than previous data. The data are compared with model predictions from different isobar and quark models that give a good description of p(gamma,K+)Lambda and p(gamma,K+)Sigma0 data in the same energy range. None of the models yield an adequate description of the data at all energies.
Pion-nucleon amplitude near threshold the sigma-term and scattering lengths beyond few loops
Kondratyuk, S
2002-01-01
The pion-nucleon amplitude is considered in the vicinity of the elastic scattering threshold within a relativistic dynamical model dressing the $\\pi N N$ and $\\pi N \\Delta$ vertices self-consistently with an infinite number of meson loops. The dressing is formulated as solution of a system of coupled integral equations incorporating unitarity, crossing symmetry and analyticity constraints. The calculated scattering lengths and the sigma-term agree with recent data analyses. In this model multiple loops are significant both below and at threshold. The contribution of the $\\Delta$ resonance is discussed, including effects of its dressing. A comparison with the approaches of chiral perturbation theory and the Bethe-Salpeter equation is outlined.
Model Companions of T_\\sigma for stable T
Baldwin, John; Shelah, Saharon
2001-01-01
Let T be a complete first order theory in a countable relational language L . We assume relation symbols have been added to make each formula equivalent to a predicate. Adjoin a new unary function symbol sigma to obtain the language L_sigma; T_sigma is obtained by adding axioms asserting that sigma is an L-automorphism. We provide necessary and sufficient conditions for T_sigma to have a model companion when T is stable. Namely, we introduce a new condition: T_sigma admits obstructions, and s...
Multiple sigma subunits and the partitioning of bacterial transcription space.
Gruber, Tanja M; Gross, Carol A
2003-01-01
Promoter recognition in eubacteria is carried out by the initiation factor sigma, which binds RNA polymerase and initiates transcription. Cells have one housekeeping factor and a variable number of alternative sigma factors that possess different promoter-recognition properties. The cell can choose from its repertoire of sigmas to alter its transcriptional program in response to stress. Recent structural information illuminates the process of initiation and also shows that the two key sigma domains are structurally conserved, even among diverse family members. We use the sigma repertoire of Escherichia coli, Bacillus subtilis, Streptomyces coelicolor, and cyanobacteria to illustrate the different strategies utilized to organize transcriptional space using multiple sigma factors.
Region 4 of sigma as a target for transcription regulation.
Dove, Simon L; Darst, Seth A; Hochschild, Ann
2003-05-01
Bacterial sigma factors play a key role in promoter recognition, making direct contact with conserved promoter elements. Most sigma factors belong to the sigma70 family, named for the primary sigma factor in Escherichia coli. Members of the sigma70 family typically share four conserved regions and, here, we focus on region 4, which is directly involved in promoter recognition and serves as a target for a variety of regulators of transcription initiation. We review recent advances in the understanding of the mechanism of action of regulators that target region 4 of sigma.
Tintut, Y; Gralla, J D
1995-10-01
Sigma 54 is a minor bacterial sigma factor that is not a member of the sigma 70 family of proteins but binds the same core RNA polymerase. Previously, we identified a region of sigma 54 that is important for binding core polymerase. In this work, PCR mutagenesis was used to identify specific amino acids important for this binding. The results show that important residues are clustered most closely in a short sequence that was previously speculated to be potentially homologous to a sequence in sigma 70. The mutagenesis also identifies important residues in the flanking hydrophobic-acidic region of sigma 54, which is absent in sigma 70. Overall, the data indicate that sigma 54 binds core polymerase through a sequence homologous to that of sigma 70 but in addition uses unique motifs to modify this interaction.
Six Sigma in the process industries; Six Sigma in der Prozessindustrie
Energy Technology Data Exchange (ETDEWEB)
Bamberg, A. [Merck KgaA, Zentrale Verfahrensentwicklung, Darmstadt (Germany); Duennebier, G. [Bayer Technology Services GmbH, Leverkusen (Germany); Jaeckle, C. [Wacker Chemie AG, Burghausen (Germany); Kraemer, S. [INEOS Koeln GmbH, Koeln (Germany). Advanced Process Control, Engineering and Projects; Lamers, J. [Henkel KGaA, Duesseldorf (Germany); Piechottka, U. [Degussa AG, Hanau (Germany)
2007-07-01
Six Sigma is an established methodology supporting process improvements which originated from manufacturing industries with a strong focus on statistical methods. Its general applicability in other industries, in particular production processes in process industries, is, also due to the limited prevalence, not obvious. This contribution therefore discusses after an initial introduction of the Six Sigma methodology the special requirements of process industries and some useful extensions of the Six Sigma toolbox. The theoretical part is followed by the discussion of three successful improvement projects from three different companies in the German chemical industries to illustrate the applicability in industrial reality. (orig.)
Mooney, Rachel Anne; Landick, Robert
2003-11-15
Bacterial sigma factors compete for binding to RNA polymerase (RNAP) to control promoter selection, and in some cases interact with RNAP to regulate at least the early stages of transcript elongation. However, the effective concentration of sigmas in vivo, and the extent to which sigma can regulate transcript elongation generally, are unknown. We report that tethering sigma70 to all RNAP molecules via genetic fusion of rpoD to rpoC (encoding sigma70 and RNAP's beta' subunit, respectively) yields viable Escherichia coli strains in which alternative sigma-factor function is not impaired. beta'::sigma70 RNAP transcribed DNA normally in vitro, but allowed sigma70-dependent pausing at extended -10-like sequences anywhere in a transcriptional unit. Based on measurement of the effective concentration of tethered sigma70, we conclude that the effective concentration of sigma70 in E. coli (i.e., its thermodynamic activity) is close to its bulk concentration. At this level, sigma70 would be a bona fide elongation factor able to direct transcriptional pausing even after its release from RNAP during promoter escape.
A New Measurement of the Masses and Widths of the Sigma_c^*++ and Sigma_c^*0 Charmed Baryons
Athar, S. B.
2004-01-01
Using data recorded by the CLEO III detector at CESR, we have made measurements of some properties of the Sigma_c^{*++} and Sigma_c^{*0} charmed baryons. In particular: Gamma(Sigma_c^{*++})=14.4^{+1.6}_{-1.5}+-1.4 MeV, M(Sigma_c^{*++})-M(Lambda_c^+) = 231.5+-0.4+-0.3 MeV, Gamma(Sigma_c^{*0})=16.6^{+1.9}_{-1.7}+-1.4 MeV, M(Sigma_c^{*0})-M(Lambda_c^+) = 231.4+-0.5+-0.3 MeV.
The sigma-1 receptor: roles in neuronal plasticity and disease.
Kourrich, Saïd; Su, Tsung-Ping; Fujimoto, Michiko; Bonci, Antonello
2012-12-01
Sigma-1 receptors (Sig-1Rs) have been implicated in many neurological and psychiatric conditions. Sig-1Rs are intracellular chaperones that reside specifically at the endoplasmic reticulum (ER)-mitochondrion interface, referred to as the mitochondrion-associated ER membrane (MAM). Here, Sig-1Rs regulate ER-mitochondrion Ca(2+) signaling. In this review, we discuss the current understanding of Sig-1R functions. Based on this, we suggest that the key cellular mechanisms linking Sig-1Rs to neurological disorders involve the translocation of Sig-1Rs from the MAM to other parts of the cell, whereby Sig-1Rs bind and modulate the activities of various ion channels, receptors, or kinases. Thus, Sig-1Rs and their associated ligands may represent new avenues for treating aspects of neurological and psychiatric diseases. Published by Elsevier Ltd.
Sigma-models and Homotopy Algebras
Zeitlin, Anton M
2015-01-01
We review the relation between homotopy algebras of conformal field theory and geometric structures arising in sigma models. In particular we formulate conformal invariance conditions, which in the quasi-classical limit are Einstein equations with extra fields, as generalized Maurer-Cartan equations.
Need of Six Sigma in Education
Mehrotra, Dheeraj
2007-01-01
The marching trend of the new economic order has generated a new capsule of SIX SIGMA as a unified approach to process excellence. The tests reveal that it has transformed some of the most successful companies in the world like Motorola, GE etc. It is activated as an approach to aiming at the target by changing the culture of a company, involving…
Six Sigma and Introductory Statistics Education
Maleyeff, John; Kaminsky, Frank C.
2002-01-01
A conflict exists between the way statistics is practiced in contemporary business environments and the way statistics is taught in schools of management. While businesses are embracing programs, such as six sigma and TQM, that bring statistical methods to the forefront of management decision making, students do not graduate with the skills to…
Improving Learning Outcome Using Six Sigma Methodology
Tetteh, Godson A.
2015-01-01
Purpose: The purpose of this research paper is to apply the Six Sigma methodology to identify the attributes of a lecturer that will help improve a student's prior knowledge of a discipline from an initial "x" per cent knowledge to a higher "y" per cent of knowledge. Design/methodology/approach: The data collection method…
How Six Sigma Methodology Improved Doctors' Performance
Zafiropoulos, George
2015-01-01
Six Sigma methodology was used in a District General Hospital to assess the effect of the introduction of an educational programme to limit unnecessary admissions. The performance of the doctors involved in the programme was assessed. Ishikawa Fishbone and 5 S's were initially used and Pareto analysis of their findings was performed. The results…
Continuous selections and sigma-spaces
Repovs, Dusan; Zdomskyy, Lyubomyr
2007-01-01
Assume that X is a metrizable separable space, and each clopen-valued lower semicontinuous multivalued map Phi from X to Q has a continuous selection. Our main result is that in this case, X is a sigma-space. We also derive a partial converse implication, and present a reformulation of the Scheepers Conjecture in the language of continuous selections.
Lean Six Sigma for Service and Healthcare
de Mast, J.; Does, R.J.M.M.; de Koning, H.
2006-01-01
Lean Six Sigma is built on principles and methods that have proven themselves over the twentieth century. It has incorporated the most effective approaches and integrated them into a full programme. It offers a management structure for organizing continuous improvement of routine tasks, such as manu
Lean Six Sigma for Service and Healthcare
J. de Mast; R.J.M.M. Does; H. de Koning
2006-01-01
Lean Six Sigma is built on principles and methods that have proven themselves over the twentieth century. It has incorporated the most effective approaches and integrated them into a full programme. It offers a management structure for organizing continuous improvement of routine tasks, such as manu
The Scientific Underpinning of Lean Six Sigma
R.J.M.M. Does; J. de Mast; H. de Koning; S. Bisgaard
2007-01-01
The twentieth century saw an incredible development of professional organizations. The impact of technological advances is obvious, but besides these, innovations in management structures and methods have resulted in the highly productive organizations of today. Lean Six Sigma is not revolutionary.
Lean Six Sigma for Service and Healthcare
de Mast, J.; Does, R.J.M.M.; de Koning, H.
2006-01-01
Lean Six Sigma is built on principles and methods that have proven themselves over the twentieth century. It has incorporated the most effective approaches and integrated them into a full programme. It offers a management structure for organizing continuous improvement of routine tasks, such as
The Scientific Underpinning of Lean Six Sigma
Does, R.J.M.M.; de Mast, J.; de Koning, H.; Bisgaard, S.
2007-01-01
The twentieth century saw an incredible development of professional organizations. The impact of technological advances is obvious, but besides these, innovations in management structures and methods have resulted in the highly productive organizations of today. Lean Six Sigma is not revolutionary.
Lean Six Sigma: Stap voor stap
Does, R.J.M.M.; de Koning, H.; de Mast, J.
2008-01-01
Lean Six Sigma is de culminatie van ontwikkelingen in kwaliteitsverbetering in de 20ste eeuw. Het combineert belangrijke principes en technieken in een goed gestructureerde en geïntegreerde benadering. Het belichaamt wetenschappelijke inzichten over onderzoeksmethodologie, management en economie. In
Improving Learning Outcome Using Six Sigma Methodology
Tetteh, Godson A.
2015-01-01
Purpose: The purpose of this research paper is to apply the Six Sigma methodology to identify the attributes of a lecturer that will help improve a student's prior knowledge of a discipline from an initial "x" per cent knowledge to a higher "y" per cent of knowledge. Design/methodology/approach: The data collection method…
Six Sigma and Introductory Statistics Education
Maleyeff, John; Kaminsky, Frank C.
2002-01-01
A conflict exists between the way statistics is practiced in contemporary business environments and the way statistics is taught in schools of management. While businesses are embracing programs, such as six sigma and TQM, that bring statistical methods to the forefront of management decision making, students do not graduate with the skills to…
Extracytoplasmic function sigma factors in Pseudomonas syringae
DEFF Research Database (Denmark)
Kiil, Kristoffer; Oguiza, J.A.; Ussery, D.W.
2005-01-01
Genome analyses of the plant pathogens Pseudomonas syringae pv. tomato DC3000, pv. syringae B728a and pv. phaseolicola 1448A reveal fewer extracytoplasmic function (ECF) sigma factors than in related Pseudomonads with different lifestyles. We highlight the presence of a P. syringae-specific ECF...
SIX SIGMA: A METRIC, A METHODOLOGY AND A MANAGEMENT SYSTEM
Directory of Open Access Journals (Sweden)
Mureşan Ioana
2010-07-01
Full Text Available This article is a theoretical article regarding Six Sigma. Six Sigma has been interpreted over time within quality theory as a metric, methodology or a management system. We explain Six Sigma using a logistics context: Delivery-On-Time (DOT rate problem. It is a theoretical context useful both for academic users and practitioners. At the beginning of the paper the DOT problem is generally described, while Sigma is presented according to statisticians view in the second part of the paper. Six Sigma is then presented as a metric for process’ capability. The fourth part of this article contains details regarding Six Sigma usage as a methodology for improvement, while the fifth part of this article refers to Six Sigma as a management system which can be used at firms’ level. The last chapter is dedicated to conclusions regarding the possible use of Six Sigma in Romania.
Chugani, N.; Kumar, V.; Garza-Reyes, J. A.; Rocha-Lona, L.; Upadhyay, A.
2016-01-01
Purpose - The academic literature and research lines exploring the effect of quality improvement methods on environmental performance still remain in early stages. The purpose of this study is therefore to investigate, through a systematic review of the existing academic literature, the environmental (green) impact of using quality and operations improvement methods such as Lean, Six Sigma, and Lean Six Sigma. This includes the impact on energy saving and the usage of natural resources.\\ud \\u...
Strong $\\Sigma_bNB$ and $\\Sigma_cND$ vertices in QCD
Azizi, K; Sundu, H
2015-01-01
We study the strong interactions among the heavy bottom spin--1/2 $\\Sigma_b$ baryon, nucleon and $B$ meson as well as the heavy charmed spin--1/2 $\\Sigma_c$ baryon, nucleon and $D$ meson in the context of QCD sum rules. We calculate the corresponding strong coupling form factors defining these vertices using a three point correlation function. We obtain the numerical values of the corresponding strong coupling constants via different Dirac structures entering the calculations.
Talebian-Ashkezari, Alireza; Abolhasani, Ali Akbar
2016-01-01
We study the evolution of the "non-perturbative" metric perturbations in a Bianchi background in the long-wavelength limit. By applying the gradient expansion to the equations of motion we exhibit a generalized "Separate Universe" approach to the cosmological perturbation theory. Having found this consistent separate universe picture, we introduce the "{\\delta}M formalism" for calculating the evolution of the tensor perturbations in anisotropic inflation models in almost similar way as the so-called {\\delta}N formula for the super-horizon dynamics of the curvature perturbations. Likewise its ancestor, {\\delta}N formalism, this new method can substantially reduce the amount of calculations related to the evolution of the tensor modes.
Alternative Sigma Factors and Their Roles in Bacterial Virulence
Kazmierczak, Mark J.; Wiedmann, Martin; Boor, Kathryn J.
2005-01-01
Sigma factors provide promoter recognition specificity to RNA polymerase holoenzyme, contribute to DNA strand separation, and then dissociate from the core enzyme following transcription initiation. As the regulon of a single sigma factor can be composed of hundreds of genes, sigma factors can provide effective mechanisms for simultaneously regulating expression of large numbers of prokaryotic genes. One newly emerging field is identification of the specific roles of alternative sigma factors...
$\\bar{D}\\Sigma^*_c$ and $\\bar{D}^*\\Sigma_c$ interactions and LHCb pentaquarks
He, Jun
2016-01-01
Recently, LHCb collaboration reported the observation of two hidden-charmed resonances $P_c(4380)$ and $P_c(4450)$ consistent with hidden-charmed pentaquarks. We perform a dynamical investigation about the $\\bar{D}\\Sigma_c^*(2520)$ and $\\bar{D}^*\\Sigma_c(2455)$ interactions which are described by the meson exchanges in a quasipotential Bethe-Salpeter equation approach. Two poles around $4450$ and $4390$ MeV are produced from the $\\bar{D}^*\\Sigma_c(2455)$ interaction with spin parities $3/2^-$ and $5/2^+$, respectively. The peak for $5/2^+$ state has a comparable hight as that of $3/2^-$ state in the $J/\\psi p$ invariant mass spectrum. Another bound state with spin-parity $J^P=3/2^-$ is produced from the $\\bar{D}\\Sigma^*_c(2520)$ interaction. Such results suggest that the narrower LHCb pentaquark $P_c(4450)$ can be well interpreted as a $5/2^+$ $\\bar{D}^*\\Sigma_c(2455)$ molecular state while the $P_c(4380)$ is a $3/2^-$ $\\bar{D}^*\\Sigma_c(2455)$ molecular state mixed with other secondary origins.
Operational excellence (six sigma) philosophy: Application to software quality assurance
Energy Technology Data Exchange (ETDEWEB)
Lackner, M.
1997-11-01
This report contains viewgraphs on operational excellence philosophy of six sigma applied to software quality assurance. This report outlines the following: goal of six sigma; six sigma tools; manufacturing vs administrative processes; Software quality assurance document inspections; map software quality assurance requirements document; failure mode effects analysis for requirements document; measuring the right response variables; and questions.
Incorporating Six Sigma Methodology Training into Chemical Engineering Education
Dai, Lenore L.
2007-01-01
Six Sigma is a buzz term in today's technology and business world and there has been increasing interest to initiate Six Sigma training in college education. We have successfully incorporated Six Sigma methodology training into a traditional chemical engineering course, Engineering Experimentation, at Texas Tech University. The students have…
Incorporating Six Sigma Methodology Training into Chemical Engineering Education
Dai, Lenore L.
2007-01-01
Six Sigma is a buzz term in today's technology and business world and there has been increasing interest to initiate Six Sigma training in college education. We have successfully incorporated Six Sigma methodology training into a traditional chemical engineering course, Engineering Experimentation, at Texas Tech University. The students have…
The cholinergic system, sigma-1 receptors and cognition
van Waarde, Aren; Ramakrishnan, Nisha K.; Rybczynska, Anna A.; Elsinga, Philip H.; Ishiwata, Kiichi; Nijholt, Ingrid M.; Luiten, Paul G. M.; Dierckx, Rudi A.
2011-01-01
This article provides an overview of present knowledge regarding the relationship between the cholinergic system and sigma-1 receptors, and discusses potential applications of sigma-1 receptor agonists in the treatment of memory deficits and cognitive disorders. Sigma-1 receptors, initially consider
A deep look into the cores of young clusters I. sigma-Orionis
Bouy, H; Martín, E L; Marchis, F; Navascues, D Barrado y; Kolb, J; Marchetti, E; Petr-Gotzens, M G; Sterzik, M; Ivanov, V D; Köhler, R; Nürnberger, D
2008-01-01
Nearby young clusters are privileged places to study the star formation history. Over the last decade, the sigma-Orionis cluster has been a prime location for the study of young very low mass stars, substellar and isolated planetary mass objects and the determination of the initial mass function. To extend previous studies of this association to its core, we searched for ultracool members and new multiple systems within the 1.5'x1.5' central region of the cluster. We obtained deep multi-conjugate adaptive optics (MCAO) images of the core of the sigma-Orionis cluster with the prototype MCAO facility MAD at the VLT using the H and Ks filters. These images allow us to reach Delta H~5mag as close as 0.2" on a typical source with H=14.5mag. These images were complemented by archival SofI Ks-band images and Spitzer IRAC and MIPS mid-infrared images. We report the detection of 2 new visual multiple systems, one being a candidate binary proplyd and the other one a low mass companion to the massive star sigma Ori E. O...
Malik, Maninder; Rangel-Barajas, Claudia; Mach, Robert H; Luedtke, Robert R
2016-09-01
Several receptor mediated pathways have been shown to modulate the murine head twitch response (HTR). However, the role of sigma receptors in the murine (±)-2,5-dimethoxy-4-iodoamphetamine (DOI)-induced HTR has not been previously investigated. We examined the ability of LS-1-137, a novel sigma-1 vs. sigma-2 receptor selective phenylacetamide, to modulate the DOI-induced HTR in DBA/2J mice. We also assessed the in vivo efficacy of reference sigma-1 receptor antagonists and agonists PRE-084 and PPCC. The effect of the sigma-2 receptor selective antagonist RHM-1-86 was also examined. Rotarod analysis was performed to monitor motor coordination after LS-1-137 administration. Radioligand binding techniques were used to determine the affinity of LS-1-137 at 5-HT2A and 5-HT2C receptors. LS-1-137 and the sigma-1 receptor antagonists haloperidol and BD 1047 were able to attenuate a DOI-induced HTR, indicating that LS-1-137 was acting in vivo as a sigma-1 receptor antagonist. LS-1-137 did not compromise rotarod performance within a dose range capable of attenuating the effects of DOI. Radioligand binding studies indicate that LS-1-137 exhibits low affinity binding at both 5-HT2A and 5-HT2C receptors. Based upon the results from these and our previous studies, LS-1-137 is a neuroprotective agent that attenuates the murine DOI-induced HTR independent of activity at 5-HT2 receptor subtypes, D2-like dopamine receptors, sigma-2 receptors and NMDA receptors. LS-1-137 appears to act as a sigma-1 receptor antagonist to inhibit the DOI-induced HTR. Therefore, the DOI-induced HTR can be used to assess the in vivo efficacy of sigma-1 receptor selective compounds.
Narrow structure in {Lambda}d scattering near the {Sigma} threshold ({sub {Sigma}}{sup 3}He states)
Energy Technology Data Exchange (ETDEWEB)
Gibson, B.F. [Los Alamos National Lab., NM (United States); Afnan, I.R. [Flinders Univ. of South Australia, Bedford Park (Australia). School of Physical Sciences
1991-12-31
A separable-potential, Faddeev-type calculation of {Lambda}-deuteron scattering near the threshold for {Sigma} production is shown to produce structure (a resonance peak) in the cross section which lies below the {Sigma} threshold for two different YN ({Lambda}N-{Sigma}N coupled-channel) potential models. In one case the {Sigma}NN eigenvalue corresponds to a pole which lies below threshold (bound) and in the second case the poles lies above the threshold.
African Journals Online (AJOL)
chifaou.amzat
2013-09-28
Sep 28, 2013 ... lions de barils par jour à environ 1 million au plus fort de la crise du Delta ... (JTF) between 13 May 2009 and 4 October 2009 (the deadline for embrac- ..... He had just ended his welcome address as the occasion's chairman.
SEMICONDUCTOR INTEGRATED CIRCUITS: 4 GHz bit-stream adder based on ΣΔ modulation
Yong, Liang; Zhigong, Wang; Qiao, Meng; Xiaodan, Guo
2010-08-01
The conventional circuit model of a bit-stream adder based on sigma delta (ΣΔ) modulation is improved with pipeline technology to make it work correctly at high frequencies. The integrated circuit (IC) of the bit-stream adder is designed with the source coupled logic structure and designed at the transistor level to increase the operating frequency. The IC is fabricated in TSMC's 0.18-μm CMOS process. The chip area is 475 × 570 μm2. A fully digital ΣΔ signal generator is designed with a field programmable gate array to test the chip. Experimental results show that the chip meets the function and performance demand of the design, and the chip can work at a frequency of higher than 4 GHz. The noise performance of the adder is analyzed and compared with both theory and experimental results.
Behrens, F; Grüsser, O J; Weiss, L R
1999-02-01
Eye position and angular velocity were measured in squirrel monkeys (Saimiri sciureus) by means of the electromagnetic scleral search-coil technique. Horizontal sigma-optokinetic nystagmus (sigma-OKN) was elicited by a stationary, stroboscopically illuminated, periodic, vertical-stripe pattern lining a vertical cylinder. The relationship between the mean slow-phase eye angular velocity, Ve, of sigma-OKN and the product of pattern period, Ps, and flash frequency, f(s), was determined. When Ve approximated k x Ps x f(s) (deg x s(-1)) and k was an integer > or = 1, the sigma-paradigm was fulfilled. Sigma-OKN could be evoked in different "modes", whereby k approximated 1, 2,...n. The sigma-OKN properties of squirrel monkeys were similar to those measured for sigma-OKN in the "stare" mode in man, with the exception of a long-lasting optokinetic afternystagmus (sigma-OKAN) appearing in the monkey. A considerable amount of temporal variability in flash sequence intervals ("temporal noise"), causing retinal error signals that interfered with the sigma-paradigm, was accepted by the visuo-motor system without interruption of sigma-OKN. This observation was explained by the operation of a short memory device for perception of visual motion. The internal gain, g(i), which relates the retinal "error" displacement velocity, Vr, and Ve depended, in turn, on Vr according to a function resembling the known relationship between neuronal activity of NOT (nucleus of the optic tract) nerve cells and Vr. This observation may be taken as direct proof that sigma-OKN can be explained by a centrally preprogrammed relationship between the retinal velocity, Vr, and the OKN slow-phase eye velocity, Ve. It is stipulated that the sum of Vr and efference copy signals generated in cortical or subcortical gaze centers is the essential component controlling the perceived velocity of the sigma-movement, whereby a short-term integrator plays a role for squirrel monkey sigma-OKN. When the flash
Value Engineering Synergies with Lean Six Sigma
2010-09-01
70 Ibid. 71 Cook, Michael J., “How to Get Six Sigma Companies to Use VM and Function Analysis ,” in SAVE International 43rd Annual Conference...Voice of Customer Strengths, Weaknesses, Opportunities, and Threats ( SWOT ) Project Charter Benchmarking Design for Assembly Pareto Analysis Tear...initiative has different phases in its methodological approach: • VE phases are orientation, information, function analysis , creative, evaluation
Sigma-Model Solitons on Noncommutative Spaces
Dabrowski, Ludwik; Landi, Giovanni; Luef, Franz
2015-12-01
We use results from time-frequency analysis and Gabor analysis to construct new classes of sigma-model solitons over the Moyal plane and over noncommutative tori, taken as source spaces, with a target space made of two points. A natural action functional leads to self-duality equations for projections in the source algebra. Solutions, having nontrivial topological content, are constructed via suitable Morita duality bimodules.
Lean six sigma project for productivity enhancement
Morais, Valter Rocha; Sousa, Sérgio; Lopes, Isabel da Silva
2016-01-01
The competitive market that companies are facing nowadays leads them to introduce frequently new products and, therefore, producing small series. This dynamic environment requires frequent changes in production lines and requires flexibility in the processes, which can cause reductions in the level of quality and productivity. This paper presents a Lean Six Sigma improvement project performed in a production line of the machining sector of a company from the motorcycles components branch. The...
Non-Linear Sigma Model on Conifolds
Parthasarathy, R
2002-01-01
Explicit solutions to the conifold equations with complex dimension $n=3,4$ in terms of {\\it{complex coordinates (fields)}} are employed to construct the Ricci-flat K\\"{a}hler metrics on these manifolds. The K\\"{a}hler 2-forms are found to be closed. The complex realization of these conifold metrics are used in the construction of 2-dimensional non-linear sigma model with the conifolds as target spaces. The action for the sigma model is shown to be bounded from below. By a suitable choice of the 'integration constants', arising in the solution of Ricci flatness requirement, the metric and the equations of motion are found to be {\\it{non-singular}}. As the target space is Ricci flat, the perturbative 1-loop counter terms being absent, the model becomes topological. The inherent U(1) fibre over the base of the conifolds is shown to correspond to a gauge connection in the sigma model. The same procedure is employed to construct the metric for the resolved conifold, in terms of complex coordinates and the action ...
Thirunavukkarasu, Nagarajan; Mishra, Mukti Nath; Spaepen, Stijn; Vanderleyden, Jos; Gross, Carol A; Tripathi, Anil K
2008-07-01
Strains Sp7 and Cd of Azospirillum brasilense, a plant growth-promoting rhizobacterium, differ in synthesis of carotenoids. While colonies of strain Sp7 have a white-cream colour on plates, colonies of strain Cd are orange-pink coloured because of the synthesis of carotenoids. Screening of a mini-Tn5 mutant library of A. brasilense Sp7 revealed two orange-pink-coloured mutants that produced carotenoids. Cloning and sequencing of the Tn5 flanking region in both the carotenoid-producing mutants of Sp7 revealed insertion of Tn5 in an ORF encoding anti-sigma factor, a ChrR-like protein. The upstream region of the Tn5-mutated ORF contained another ORF that encoded an extra-cytoplasmic function (ECF)-class sigma factor (sigma(E), RpoE). When the nucleotide sequences of the corresponding ORFs from the carotenoid-producing strain Cd were analysed, the sequence of the Cd sigma(E) was identical to that of the carotenoid non-producing strain Sp7, but the Cd anti-sigma(E) ORF had a deletion that caused frame shifting and creation of a stop codon. This resulted in the premature termination of the protein, which was about 7 kDa smaller than the Sp7 anti-sigma(E). Cloning of Sp7 anti-sigma(E) in a broad-host-range expression vector and expression in A. brasilense Cd and in the anti-sigma(E) knockout mutant of A. brasilense Sp7 resulted in the inhibition of carotenoid synthesis. Similarly, cloning and overexpression of A. brasilense Sp7 sigma(E) in A. brasilense Sp7 resulted in the production of carotenoids. These observations clearly indicate that carotenoid synthesis in A. brasilense is controlled by sigma(E) with its cognate anti-sigma(E).
Six sigma and lean production adoption in a manufacturing company
Directory of Open Access Journals (Sweden)
Alisson Christian Scheller
2014-11-01
Full Text Available The connection among Lean Production with Six Sigma originated the Lean Six Sigma methodology, focused on processes variation and waste reduction. This methodology was developed on different ways in the companies and there is no consensus over its structure and its implementation. In this context, this paper aims to identify and analyze the main characteristics on the adoption and integration of Lean Six Sigma methodology through a case study conducted in a manufacturing company that adopts lean production and six sigma. The results show two important aspects of the Lean Six Sigma methodology. One of them is the adoption of the value stream mapping as a central tool on Lean Six Sigma. The other is the use of DMAIC for improvements actions. The study indicates that despite the difficulties on Lean Six Sigma implementation, the methodology offers benefits to the company that adopts it in the suitable way.
Rad-Hard Sigma-Delta 3-channel ADC for Fluxgate Magnetometers Project
National Aeronautics and Space Administration — The proposed project aims to develop a multi-channel analog to digital converter (ADC) required for a fluxgate magnetometer (EPD) employed on NASA's planetary...
Design and implementation of a sigma delta technology based pulse oximeter's acquisition stage
Rossi, E. E.; Peñalva, A.; Schaumburg, F.
2011-12-01
Pulse oximetry is a widely used tool in medical practice for estimating patient's fraction of hemoglobin bonded to oxygen. Conventional oximetry presents limitations when changes in the baseline, or low amplitude of signals involved occur. The aim of this paper is to simultaneously solve these constraints and to simplify the circuitry needed, by using ΣΔ technology. For this purpose, a board for the acquisition of the needed signals was developed, together with a PC managed software which controls it, and displays and processes in real time the information acquired. Also laboratory and field tests where designed and executed to verify the performance of this equipment in adverse situations. A simple, robust and economic instrument was achieved, capable of obtaining signals even in situations where conventional oximetry fails.
Basic Consideration for Signal Processing Solutions Used in Sigma-delta Based ADC and DAC Converters
Directory of Open Access Journals (Sweden)
ANTONESEI, G.
2010-02-01
Full Text Available During the last decade there was an explosion in the field of mobile multimedia devices that led to the emergence of new and very complex requirements for the producers of integrated circuits (IC's. Practically, many of the difficulties localized in the systems made with multiple discrete IC's have moved one level down, inside the IC itself (this is how the concept of System on Chip came up. This paper presents exactly such an example in which the audio section of a mobile phone must coexist with the intermediate radio frequency section in a single IC. It starts by mentioning the technical challenges facing this request, followed by an introduction of the fundamental theories used in finding the most efficient solution.
Gravació de senyal de veu en format sigma-delta
2005-01-01
Los objetivos principales del proyecto son el estudio de sistemas de conversión de señales analógicas a digitales, para ello se prestará especial atención al sistema convencional de modulación de voz, llamado PCM, y se comparará con otras arquitecturas denominadas de bajos bits, puesto que utilizan muchos menos bits para llevar a cabo la conversión, en ocasiones tan solo 1 bit. En este proceso se verán los diferentes pasos que son realizados para digitalizar una señal analógica (muestreo, cua...
First Observation of Heavy Baryons \\Sigma_b and \\Sigma_b^*
Aaltonen, T; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bölla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, Yu A; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca-Almenar, C; Cuevas-Maestro, J; Culbertson, R; Cully, J C; Da Ronco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; De Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'Orso, Mauro; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dorr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernández, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; García, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gómez, G; Gómez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Group, R C; Grundler, U; Guimarães da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Höcker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; LeCompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; MacQueen, D; Madrak, R; Maeshima, K; Makhoul, K; Mäki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martinez-Ballarin, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtälä, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Movilla-Fernández, P A; Mülmenstädt, J; Mukherjee, A; Müller, T; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Österberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, Aldo L; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P B; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Salto, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T G; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakian, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Söderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Saint-Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Tesarek, R J; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; Van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobuev, I P; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S
2007-01-01
We report an observation of new bottom baryons produced in proton-antiproton collisions at the Tevatron. Using 1.1 fb^{-1} of data collected by the CDF II detector, we observe four \\Lambda_b^0\\pi^{\\pm} resonances in the fully reconstructed decay mode \\Lambda_b^0 \\to \\Lambda_c^+ \\pi^-, where \\Lambda_c^+ \\to p K^- \\pi^+. We interpret these states as the \\Sigma_b^{(*)\\pm} baryons and measure their masses to be: m_{\\Sigma_b^+} = 5807.8^{+2.0}_{-2.2} (stat.) \\pm 1.7 (syst.) MeV/c^2 m_{\\Sigma_b^-} = 5815.2 \\pm 1.0 (stat.) \\pm 1.7 (syst.) MeV/c^2 m_{\\Sigma_b^{*+}} = 5829.0^{+1.6}_{-1.8} (stat.) ^{+1.7}_{-1.8} (syst.) MeV/c^2 m_{\\Sigma_b^{*-}} = 5836.4 \\pm 2.0 (stat.) ^{+1.8}_{-1.7} (syst.) MeV/c^2
K^0 pi^0 Sigma^+ and K^*0 Sigma^+ photoproduction off the proton
Nanova, M; Bantes, B; Bartholomy, O; Bayadilov, D; Beck, R; Beloglasov, Yu A; Castelijns, R; Credé, V; Dutz, H; Ehmanns, A; Elsner, D; Essig, K; Ewald, R; Fabry, I; Fornet-Ponse, K; Fuchs, M; Funke, C; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Hoffmeister, P; Horn, I; Jaegle, I; Junkersfeld, J; Kalinowsky, H; Kammer, S; Kleber, V; Klein, Frank; Klein, Friedrich; Klempt, E; Konrad, M; Kotulla, M; Krusche, B; Lang, M; Langheinrich, J; Löhner, H; Lopatin, I V; Lotz, J; Lugert, S; Menze, D; Messchendorp, J G; Mertens, T; Metag, V; Morales, C; Novinski, D V; Novotny, R; Ostrick, M; Pant, L M; Van Pee, H; Pfeiffer, M; Radkov, A; Roy, A; Schadmand, S; Schmidt, C; Schmieden, H; Schoch, B; Shende, S V; Sokhoyan, V; Sule, A; Sumachev, V V; Szczepanek, T; Thoma, U; Trnka, D; Varma, R; Walther, D; Weinheimer, C; Wendel, C
2008-01-01
The exclusive reactions $\\gamma p \\to K^{*0} \\Sigma^+(1189)$ and $\\gamma p \\to K^{0} \\pi^{0}\\Sigma^+(1189)$, leading to the p 4$\\pi^{0}$ final state, have been measured with a tagged photon beam for incident energies from threshold up to 2.5 GeV. The experiment has been performed at the tagged photon facility of the ELSA accelerator (Bonn). The Crystal Barrel and TAPS detectors were combined to a photon detector system of almost 4$\\pi$ geometrical acceptance. Differential and total cross sections are reported. At energies close to the threshold, a flat angular distribution has been observed for the reaction $\\gamma p\\to K^{0} \\pi^{0}\\Sigma^+$ suggesting dominant s-channel production. $\\Sigma^*(1385)$ and higher lying hyperon states have been observed. An enhancement in the forward direction in the angular distributions of the reaction $\\gamma p \\to K^{*0}\\Sigma^+$ indicates a $t$-channel exchange contribution to the reaction mechanism. The experimental data are in reasonable agreement with recent theoretical ...
Energy Technology Data Exchange (ETDEWEB)
K. Joo
2003-05-01
The polarized longitudinal-transverse structure function sigma_LT'in the p(e,e'p)pi^0 reaction has been measured for the first time in the Delta(1232) resonance region for invariant mass W = 1.1 - 1.3 GeV and at four-momentum transfer Q^2 = 0.40 and 0.65 GeV^2. Data were taken at the Thomas Jefferson National Accelerator Facility with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. This newly measured sigma_LT' provides new and unique information on the interference between resonant and non-resonant amplitudes in the Delta(1232) resonance region. The comparison to recent phenomenological calculations shows sensitivity to the description of non-resonant amplitudes and higher resonances.
Energy Technology Data Exchange (ETDEWEB)
K. Joo
2003-05-01
The polarized longitudinal-transverse structure function sigma_LT'in the p(e,e'p)pi^0 reaction has been measured for the first time in the Delta(1232) resonance region for invariant mass W = 1.1 - 1.3 GeV and at four-momentum transfer Q^2 = 0.40 and 0.65 GeV^2. Data were taken at the Thomas Jefferson National Accelerator Facility with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. This newly measured sigma_LT' provides new and unique information on the interference between resonant and non-resonant amplitudes in the Delta(1232) resonance region. The comparison to recent phenomenological calculations shows sensitivity to the description of non-resonant amplitudes and higher resonances.
DELTAS: A new Global Delta Sustainability Initiative (Invited)
Foufoula-Georgiou, E.
2013-12-01
Deltas are economic and environmental hotspots, food baskets for many nations, home to a large part of the world population, and hosts of exceptional biodiversity and rich ecosystems. Deltas, being at the land-water interface, are international, regional, and local transport hubs, thus providing the basis for intense economic activities. Yet, deltas are deteriorating at an alarming rate as 'victims' of human actions (e.g. water and sediment reduction due to upstream basin development), climatic impacts (e.g. sea level rise and flooding from rivers and intense tropical storms), and local exploration (e.g. sand or aggregates, groundwater and hydrocarbon extraction). Although many efforts exist on individual deltas around the world, a comprehensive global delta sustainability initiative that promotes awareness, science integration, data and knowledge sharing, and development of decision support tools for an effective dialogue between scientists, managers and policy makers is lacking. Recently, the international scientific community proposed to establish the International Year of Deltas (IYD) to serve as the beginning of such a Global Delta Sustainability Initiative. The IYD was proposed as a year to: (1) increase awareness and attention to the value and vulnerability of deltas worldwide; (2) promote and enhance international and regional cooperation at the scientific, policy, and stakeholder level; and (3) serve as a launching pad for a 10-year committed effort to understand deltas as complex socio-ecological systems and ensure preparedness in protecting and restoring them in a rapidly changing environment. In this talk, the vision for such an international coordinated effort on delta sustainability will be presented as developed by a large number of international experts and recently funded through the Belmont Forum International Opportunities Fund. Participating countries include: U.S., France, Germany, U.K., India, Japan, Netherlands, Norway, Brazil, Bangladesh
A comparison of simulated precipitation by hybrid isentropic-sigma and sigma models
Johnson, Donald R.; Zapotocny, Tom H.; Reames, Fred M.; Wolf, Bart J.; Pierce, R. B.
1993-01-01
Simulations of dry and moist baroclinic development from 10- and 22-layer hybrid isentropic-sigma coordinate models are compared with those from 11-, 27-, and 35-layer sigma coordinate models. The ability of the models to transport water vapor and simulate equivalent potential temperature is examined. Predictions of the timing, location, and amount of precipitation are compared. Several analytical distributions of water vapor are specified initially. It is shown that when the relative humidity is vertically uniform through a substantial extent of the atmosphere, all the models produce very similar precipitation distributions. However, when water vapor is confined to relatively shallow layers, the ability of the sigma coordinate models to simulate the timing, location, and amount of precipitation is severely compromised.
N-Delta(1232) axial form factors from weak pion production
Hernandez, E; Valverde, M; Vicente-Vacas, M J
2010-01-01
The N-Delta axial form factors are determined from neutrino induced pion production ANL & BNL data by using a state of the art theoretical model, which accounts both for background mechanisms and deuteron effects. We find violations of the off diagonal Goldberger-Treiman relation at the level of 2 sigma which might have an impact in background calculations for T2K and MiniBooNE low energy neutrino oscillation precision experiments.
Energy Technology Data Exchange (ETDEWEB)
Aubert, B.
2007-09-14
We study the e+e- --> Lambda anti-Lambda gamma, Lambda anti-Sigma0 gamma, Sigma0 anti-Sigma0 gamma processes using 230 fb-1 of integrated luminosity collected by the BaBar detector at e+e- center-of-mass energy of 10.58 GeV. From the analysis of the baryon-antibaryon mass spectra the cross sections for e+e- --> Lambda anti-Lambda, Lambda anti-Sigma0, Sigma0 anti-Sigma0 are measured in the dibaryon mass range from threshold up to 3 GeV/c{sup 2}. The ratio of electric and magnetic form factors, |G{sub E}/G{sub M}|, is measured for e+e- --> Lambda anti-Lambda, and limits on the relative phase between Lambda form factors are obtained. We also measure the J/psi --> Lambda anti-Lambda, Sigma0 anti-Sigma0 and psi(2S) --> Lambda anti-Lambda branching fractions.
CP Violation in the Linear Sigma Model
Mizher, Ana Júlia
2009-01-01
Motivated by the possibility of the formation of CP-odd domains in heavy ion collisions, we investigate the effects of CP violation on the chiral transition within the linear sigma model with two flavors of quarks. We also study how the CP-odd system is affected by the presence of a strong magnetic field, that is presumably generated in a non-central heavy ion collision. We find that both ingredients play an important role, influencing drastically the nature of the phase transition and the critical temperature.
CP Violation in the Linear Sigma Model
Mizher, Ana Júlia; Fraga, Eduardo S.
2008-01-01
Motivated by the possibility of the formation of CP-odd domains in heavy ion collisions, we investigate the effects of CP violation on the chiral transition within the linear sigma model with two flavors of quarks. We also study how the CP-odd system is affected by the presence of a strong magnetic field, that is presumably generated in a non-central heavy ion collision. We find that both ingredients play an important role, influencing drastically the nature of the phase transition and the cr...