Double Conversion Research Articles

Spinal Muscular Atrophy Due to Double Gene Conversion Event

ABSTRACTSpinal muscular atrophy (SMA) is an autosomal recessive disease characterized by degeneration of the anterior horn cells of the spinal cord. The survival motor neuron (SMN) gene has been identified as an SMA-determining gene. SMN exists as two copies in 5q13, and deletions in exons 7 and 8 of the telomeric copy (SMNT) occur in 95% of patients, regardless of disease severity. In a minority of patients, exon 7 but not exon 8 of SMNT appears deleted. We now report a patient with typical features of SMA type II who carried homozygous deletions of SMNT exon 7 and centromeric SMN (SMNC) exon 8 but retained SMNT exon 8 and SMNC exon 7. Sequence analysis demonstrated that SMNC exon 7 was adjacent to SMNT exon 8 on both SMN copies, indicating a double conversion. We confirm that sequence conversion is a common event in SMA and is associated with the milder form of the disease. The severity, however, can be modified in either positive or negative direction by other factors.

New frequency translation technique for FM-CW reflectometry

In broadband microwave reflectometry, coherent detection is widely used to obtain the phase information and to improve the systems sensitivity, both in diagnostics measuring the electronic density profile and plasma fluctuations. Coherent detection uses a translated version of the probing signal to guarantee a stable intermediate frequency. Here, a novel technique to generate the frequency translation by double frequency conversion is presented and its advantages over the commonly used single frequency conversion techniques employing image rejection mixers are discussed. The results obtained with the new frequency translator modules developed for the three JET FM-CW reflectometers, operating successfully at JET since mid-2009, are presented.

Generation of double femtosecond pulses by using two transmissive gratings

Double femtosecond laser pulses are usually generated by using a Michelson structure. We propose a novel and simple device by using two high-density transmissive gratings for generation of double pulses and conversion between single and double laser pulses by shifting one of the two gratings by a quarter period. The apparatus has the advantages of compact volume, simple structure, and convenience in manipulation. Experimental outputs of the double laser pulses are well verified in experiment, which can be properly explained by numerical simulation with the rigorous coupled-wave theory. This structure provides an interesting approach for generation of double pulses and conversion between single and double laser pulses for practical applications of the femtosecond laser.

Preparation and characterisation of composite double phosphate conversion coatings on AZ91D magnesium alloy

A composite double zinc phosphate conversion coating was obtained via forming a hopeite crystal layer on an amorphous phosphate layer on the AZ91D magnesium alloy. The surface morphology, structure and phase composition of the composite coating were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). As a comparison, the single zinc phosphate coating and the bare substrate were also discussed. The phosphate crystal clusters can form on the amorphous layer densely and fine. According to the open circuit potential (OCP) and potentiodynamic polarisation curve tests, the composite phosphate conversion coating on the AZ91D magnesium alloy yielded the best protective effect compared with the single amorphous layer and crystal layer.

Double Conversion Uninterrupted Energy System With Rectifier And The Inverter Integration

This paper presents the design, implementation and experimental results of a double conversion uninterrupted power supply (UPS), with integration of the rectifier and the inverter stages. The system is composed by a rectifier and an inverter, which employs a single-pole strategy for the switching modulation. The main system characteristics are: the control assembled with commercial integrated circuits, and the unified circuit of the rectifier and the inverter. Theoretical analysis, operation principle, and topology details are presented and validated through experimental results.

Kink effect upon the electromagnetic generation of ultrasound in isotropic ferromagnets

The influence of the shape anisotropy on the field dependences of double electromagnetic-acoustic conversion in samples of an Invar alloy 29NK in the high-temperature range below the Curie point is experementally studied. It is shown that at a constant temperature the value of the polarizing field in which a jumplike generation of ultrasound occurs is determined by the demagnetizing factor of the sample, and the observed anomaly of the electromagnetic-acoustic conversion is caused by the kink effect.

The choice of torsional or longitudinal excitation in guided wave pipe inspection

Long-range screening of pipework using guided waves is now in routine industrial use. The T(0,1) mode is generally preferable to the L(0,2) mode as the transduction system required is simpler and lighter. The L(0,2) mode may be useful in a small number of cases but tests reported here demonstrate that it is unlikely to be useful in liquid-filled pipes. It also tends to give poorer signal-to-noise ratio, and a double mode conversion phenomenon can give extra echoes that could be incorrectly called as defects. In principle it is possible to test each length of pipe using both modes, though at a considerable penalty in equipment complexity, weight and cost. It is argued that if increased confidence is required, a better strategy generally is to test each section of pipe from both directions using the torsional mode.

A CMOS image-rejection mixer with 58-dB IRR for DTV receivers

The design, implementation, and characterization of an image-rejection double quadrature conversion mixer based on RC asymmetric polyphase filters (PPF) are presented. The mixer consists of three sets of PPFs and a mixer core for quadrature down conversion. Two sets of PPFs are used for the quadrature generation and the other one is used for the IF signal selection to reject the unwanted image band. Realized in 0.18-μm CMOS technology as a part of the DVB-T receiver chip, the mixer exhibits a high image rejection ratio (IRR) of 58 dB, a power consumption of 11 mW, and a 1-dB gain compression point of −15 dBm.

Dirac-neutrino magnetic moment and the dynamics of a supernova explosion

The double conversion of the neutrino helicity $\nu_L \to \nu_R \to \nu_L$ has been analyzed for supernova conditions, where the first stage is due to the interaction of the neutrino magnetic moment with plasma electrons and protons in the supernova core, and the second stage, due to the resonance spin flip of the neutrino in the magnetic field of the supernova envelope. It is shown that, in the presence of the neutrino magnetic moment in the range $10^{-13} \mu_{\rm B} < \mu_\nu < 10^{-12} \mu_{\rm B}$ and a magnetic field of $\sim 10^{13}$ G between the neutrinosphere and the shock-stagnation region, an additional energy of about $10^{51}$ erg, which is sufficient for a supernova explosion, can be injected into this region during a typical shock-stagnation time.

Advanced Soldier-Based Thermoelectric Power Systems Using Battlefield Heat Sources

AbstractThe U.S. military uses large amounts of fuel during deployments and battlefield operations. Consequently, the U.S. military has a strong need to develop technologies that increase fuel efficiency and minimize fuel requirements all along the logistics trail and in all battlefield operations. There are additional requirements to reduce and minimize the environmental footprint of various military equipment and operations and reduce the need for batteries (non-rechargeable) in battlefield operations. The tri-agency SERDP (Strategic Environmental Research and Development Program) office is sponsoring a challenging, high-payoff project to develop a lightweight, small form-factor, soldier-portable advanced thermoelectric generator (TEG) system prototype to recover and convert waste heat from a variety of deployed equipment with the ultimate purpose of obtaining additional power for soldier battery charging, advanced capacitor charging, and other battlefield power applications. The project seeks to achieve power conversion efficiencies of 10% (double current commercial TE conversion efficiencies) in a system with ˜1.6-kW power output for a spectrum of battlefield power applications. In order to meet this objective, the project is taking on the multi-faceted challenges of tailoring LAST/LASTT-based thermoelectric (TE) materials for the proper temperature ranges (300 K – 700 K), fabricating these materials with cost-effective hot-pressed and sintered processes while maintaining their TE properties, measuring and characterizing their thermal fatigue and structural properties, developing the proper manufacturing processes for the TE materials and modules, designing and fabricating the necessary microtechnology heat exchangers, and fabricating and testing the final TEG system. The ultimate goal is to provide an opportunity to deploy these TEG systems in a wide variety of current military equipment. This would help the Army in achieving one of the Office of Secretary of Defense’s major strategic objectives to maintain and enhance operational effectiveness while reducing total force energy demands. The presentation will review the progress made on 1) the performance of LAST / LASTT TE materials and tailoring their temperature dependency; 2) evaluating the structural (Elastic modulus, Poisson’s ratio and mechanical strength) properties of these materials, 3) development of the necessary LAST/LASTT-based TE modules, 4) development of the required hot- and cold-side microtechnology heat exchangers, and 5) the overall system designs for 30 kW and 60 kW TQG applications and potential performance pathways/differences for these two TQG cases. This work leverages critical fundamental research performed by the Office of Naval Research in developing LAST/LASTT materials.

Simplified Voltage-Sag Filler for Line-Interactive Uninterruptible Power Supplies

There are three types of static uninterruptible power supplies (UPSs): passive standby, line interactive, and double conversion. The last one protects the load against all types of line disturbances, but it is the most expensive and the one with the lowest efficiency. On the other hand, passive-standby and line-interactive UPSs have higher efficiency and lower cost, but they show an important drawback: a switching time from normal to stored-energy mode. As a consequence, there is a notch in the UPS output voltage during this switching time. In a previous paper, the authors proposed a method for filling these voltage notches with a sinusoidal waveform generated by a switch-mode converter. In this one, a simplified notch filler is proposed. It consists of two capacitors, one charged with positive voltage and the other with negative voltage. If the fault occurs in the positive period, the positive-charged capacitor is connected to the load. This connection is then modulated in order to obtain a sinusoidal waveform at the load. In the negative period, the other capacitor is used in the same way.

Precise methods for conducted EMI modeling, analysis, and prediction

Focusing on the state-of-the-art conducted EMI prediction, this paper presents a noise source lumped circuit modeling and identification method, an EMI modeling method based on multiple slope approximation of switching transitions, and double Fourier integral method modeling PWM conversion units to achieve an accurate modeling of EMI noise source. Meanwhile, a new sensitivity analysis method, a general coupling model for steel ground loops, and a partial element equivalent circuit method are proposed to identify and characterize conducted EMI coupling paths. The EMI noise and propagation modeling provide an accurate prediction of conducted EMI in the entire frequency range (0–10 MHz) with good practicability and generality. Finally a new measurement approach is presented to identify the surface current of large dimensional metal shell. The proposed analytical modeling methodology is verified by experimental results.

A concise synthesis of (R)-Bgugaine, a pyrrolidine alkaloid from arisarum vulgare

A new short method for the preparation of (R)-Bgugaine (1) has been described using Wittig condensation of a non-stabilised ylide with N-carboethoxy prolinal followed by reduction of double bond and conversion of N-carboethoxy group to N-methyl.

Electron Bernstein wave heating of over-dense H-mode plasmas in the TCV tokamak via O-X-B double mode conversion

This paper reports on the first demonstration of electron Bernstein wave heating (EBWH) by double mode conversion from ordinary (O-) to Bernstein (B-) via the extraordinary (X-) mode in an over-dense tokamak plasma, using low field side launch, achieved in the TCV tokamak H-mode, making use of its naturally generated steep density gradient. This technique offers the possibility of overcoming the upper density limit of conventional EC microwave heating. The sensitive dependence of the O-X mode conversion on the microwave launching direction has been verified experimentally. Localized power deposition, consistent with theoretical predictions, has been observed at densities well above the conventional cut-off. Central heating has been achieved, at powers up to two megawatts. This demonstrates the potential of EBW in tokamak H-modes, the intended mode of operation for a reactor such as ITER.

2.4 GHz ISM-Band Receiver Design in a 0.18 $\mu{\hbox{m}}$ Mixed Signal CMOS Process

This letter presents the design and measurement results of a fully integrated CMOS receiver front-end and voltage controlled oscillator (VCO) for 2.4 GHz industrial, scientific and medical (ISM)-band application. For low cost design, this receiver has been fabricated with a 0.18 mum thin metal CMOS process with a top metal thickness of only 0.84 mum. The receiver integrates radio frequency (RF) front-end (a single-ended low-noise amplifier (LNA) with on-chip spiral inductors and a double balanced down conversion mixer), VCO and local oscillation buffers on a single chip together with an internal output buffer. To obtain the high-quality factor inductor in LNA, VCO and down conversion mixer design, patterned-ground shields (PGS) are placed under the inductor to reduce the effect from image current of resistive Si substrate. Moreover, in VCO and mixer design, due to the incapability of using thick top metal layer of which the thickness is over 2 mum, as used in many RF CMOS process, the structure of dual-metal layer in which we make electrically short circuit between the top metal and the next metal below it by a great number of via arrays along the metal traces is adopted to compensate the Q -factor degradation. In this letter, the receiver achieves a conversion gain of 23 dB, noise figure of 8.1 dB and P1 dB of -20 dBm at 39 MHz with 21 mW power dissipation from a 1.8 V power supply. It occupies a whole circuit area of 2 mm2.

Electron Bernstein Wave Heating and Emission in the TCV Tokamak

Electron cyclotron resonance heating (ECRH) of high-density tokamak plasmas is limited because of reflections of the waves at so-called wave cutoffs. Electron Bernstein wave (EBW) heating (EBWH) via a double mode conversion process from ordinary (O)-mode, launched from the low field side, to extraordinary (X)-mode and finally to Bernstein (B)-mode offers the possibility of overcoming these density limits.In this paper, the O-X mode conversion dependence on the microwave injection angle is demonstrated experimentally. The dependence on the injection angle is studied in high-density plasmas in H-mode, in the presence of magnetohydrodynamic activity, edge-localized modes, and sawteeth. The results of localized heat deposition at an overdense location are presented, demonstrating EBWH for the first time via the O-X-B mode conversion process in a standard aspect-ratio tokamak. The results of global and local power deposition are compared with ray-tracing calculations. Moreover, a temperature increase due to EBWH is observed.Initial EBW emission measurements with a newly installed ECRH reception launcher are presented. The inverse double mode conversion process B-X-O is observed by measuring the emission for several frequencies at an optimum angle.

Light Pseudoscalar Bosons, PVLAS and the Double Pulsar J0737-3039

Light Pseudoscalar Bosons (LPBs) coupled to two photons are predicted by many realistic extensions of the Standard Model and give rise to birefringence and dichroism in a light beam travelling in an external magnetic field. These effects have recently been detected by the PVLAS collaboration, thereby strongly suggesting the existence of a LPB. We provide an astrophysical cross-check for such a claim. Actually, we show that in the double pulsar J0737-3039 photon-LPB conversion can give rise to a characteristic attenuation pattern of the light beam emitted by one of the pulsars when it goes through the magnetosphere of the companion. The effect under consideration shows up in the $\gamma$-ray band and can be detected by the upcoming GLAST mission.

A comparative analysis of the accuracy and dynamic characteristics of two systems for converting the parameters of passive electrical quantities into an active quantity

A comparative analysis of an autocompensation bridge with double conversion of the unbalance signal and a two-channel active converter with additive correction is presented. The advantages of the latter in power and speed of response are pointed out.

Design of low-cost 183 GHz subharmonic mixers for commercial applications

Techniques are presented for designing fixed-tuned millimetre-wave components with the least number of parts to minimise the cost and maximise the potential for volume manufacture. Design techniques for millimeter-wave mixer components targeted at potentially high volume applications, such as medical and security screening and nondestructive testing, require certain compromises in the use of CAD tools. The compromise techniques are demonstrated using commercially available foundry diodes in the design of a 183 GHz subharmonic mixer for earth observation applications. The resulting mixer exhibits 6.85 dB double sideband conversion loss and a mixer temperature of 988 K using 5 mW of local oscillator power at 92 GHz.

A wide band up-conversion mixer for cable television tuner

An up-conversion mixer implemented in a 0.35μm SiGe BiCMOS technology for a double conversion cable TV tuner is described. The mixer converts the 100MHz to 1000MHz band to the Intermediate Frequency of 1GHz above. The mixer meets the linearity and noise figure requirements for a TV tuner. The noise figure (IF) of 19.2∼17.5dB, 1dB compression of 12.1dBm, and gain of −1∼0.7dB in the 900MHz band are achieved at a supply voltage of 5V. The power consumption is 47mW.