The development of differential inductors using double air-bridge structure based on integrated passive device technology

NASA Astrophysics Data System (ADS)

Li, Yang; Yao, Zhao; Fu, Xiao-Qian; Li, Zhi-Ming; Shan, Fu-Kai; Wang, Cong

2017-05-01

Recently, integrated passive devices have become increasingly popular; inductor realization, in particular, offers interesting high performance for RF modules and systems. In this paper, a development of differential inductor fabricated by integrated passive devices technology using a double air-bridge structure is presented. A study of the model development of the differential inductor is first demonstrated. In this model section, a segment box analysis method is applied to provide a clear presentation of the differential inductor. Compared with other work that only shows a brief description of the process, the integrated passive devices process used to fabricate the inductor in this study is elaborated on. Finally, a characterization of differential inductors with different physical layout parameters is illustrated based on inductance and quality factors, which provides a valuable reference for realizing high performance. The proposed work provides a good solution for the design, fabrication and practical application of RF modules and systems.

Rheumatoid Arthritis-Associated Autoantibodies and Subclinical Interstitial Lung Disease: The Multi-Ethnic Study of Atherosclerosis

PubMed Central

Bernstein, Elana J.; Barr, R. Graham; Austin, John H.M.; Kawut, Steven M.; Raghu, Ganesh; Sell, Jessica L.; Hoffman, Eric A.; Newell, John D.; Watts, Jubal R.; Nath, P. Hrudaya; Sonavane, Sushil K.; Bathon, Joan M.; Majka, Darcy S.; Lederer, David J.

2016-01-01

Background Adults with interstitial lung disease (ILD) often have serologic evidence of autoimmunity of uncertain significance without overt autoimmune disease. We examined associations of rheumatoid arthritis (RA)-associated antibodies with subclinical ILD in community-dwelling adults. Methods We measured serum rheumatoid factor (RF) and anti-cyclic citrullinated peptide antibody (anti-CCP) and high attenuation areas (HAA; CT attenuation values between −600 and −250 HU) on cardiac CT in 6,736 community-dwelling U.S. adults enrolled in the Multi-Ethnic Study of Atherosclerosis. We measured interstitial lung abnormalities (ILA) in 2,907 full-lung CTs at 9.5-year median follow-up. We used generalized linear and additive models to examine associations between autoantibodies and both HAA and ILA, and tested for effect modification by smoking. Results In adjusted models, HAA increased by 0.49% (95% CI 0.11–0.86%) per doubling of RF IgM and by 0.95% (95% CI 0.50–1.40%) per RF IgA doubling. ILA prevalence increased by 11% (95% CI 3–20%) per RF IgA doubling. Smoking modified the associations of both RF IgM and anti-CCP with both HAA and ILA (interaction p-values varied from 0.01 to 0.09). Among ever smokers, HAA increased by 0.81% (95% CI 0.33–1.30%) and ILA prevalence increased by 14% (95% CI 5–24%,) per RF IgM doubling; and HAA increased by 1.31% (95% CI 0.45–2.18%) and ILA prevalence increased by 13% (95% CI 2–24%) per anti-CCP doubling. Among never smokers, no meaningful associations were detected. Conclusions RA-related autoimmunity is associated with both quantitative and qualitative subclinical ILD phenotypes on CT, particularly among ever smokers. PMID:27609750

Distributing coil elements in three dimensions enhances parallel transmission multiband RF performance: A simulation study in the human brain at 7 Tesla.

PubMed

Wu, Xiaoping; Tian, Jinfeng; Schmitter, Sebastian; Vaughan, J Tommy; Uğurbil, Kâmil; Van de Moortele, Pierre-François

2016-06-01

We explore the advantages of using a double-ring radiofrequency (RF) array and slice orientation to design parallel transmission (pTx) multiband (MB) pulses for simultaneous multislice (SMS) imaging with whole-brain coverage at 7 Tesla (T). A double-ring head array with 16 elements split evenly in two rings stacked in the z-direction was modeled and compared with two single-ring arrays consisting of 8 or 16 elements. The array performance was evaluated by designing band-specific pTx MB pulses with local specific absorption rate (SAR) control. The impact of slice orientations was also investigated. The double-ring array consistently and significantly outperformed the other two single-ring arrays, with peak local SAR reduced by up to 40% at a fixed excitation error of 0.024. For all three arrays, exciting sagittal or coronal slices yielded better RF performance than exciting axial or oblique slices. A double-ring RF array can be used to drastically improve SAR versus excitation fidelity tradeoff for pTx MB pulse design for brain imaging at 7 T; therefore, it is preferable against single-ring RF array designs when pursuing various biomedical applications of pTx SMS imaging. In comparing the stripline arrays, coronal and sagittal slices are more advantageous than axial and oblique slices for pTx MB pulses. Magn Reson Med 75:2464-2472, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Low temperature probe for dynamic nuclear polarization and multiple-pulse solid-state NMR.

PubMed

Cho, HyungJoon; Baugh, Jonathan; Ryan, Colm A; Cory, David G; Ramanathan, Chandrasekhar

2007-08-01

Here, we describe the design and performance characteristics of a low temperature probe for dynamic nuclear polarization (DNP) experiments, which is compatible with demanding multiple-pulse experiments. The competing goals of a high-Q microwave cavity to achieve large DNP enhancements and a high efficiency NMR circuit for multiple-pulse control lead to inevitable engineering tradeoffs. We have designed two probes-one with a single-resonance RF circuit and a horn-mirror cavity configuration for the microwaves and a second with a double-resonance RF circuit and a double-horn cavity configuration. The advantage of the design is that the sample is in vacuum, the RF circuits are locally tuned, and the microwave resonator has a large internal volume that is compatible with the use of RF and gradient coils.

Impact of Lateral Straggle on the Analog/RF Performance of Asymmetric Gate Stack Double Gate MOSFET

NASA Astrophysics Data System (ADS)

Sivaram, Gollamudi Sai; Chakraborty, Shramana; Das, Rahul; Dasgupta, Arpan; Kundu, Atanu; Sarkar, Chandan K.

2016-09-01

This paper presents a systematic comparative study of Analog and RF performances of an underlapped double gate (U-DG) NMOSFET with Gate Stack (GS) for varying straggle lengths. Asymmetric underlap devices (A-U-DG) have been proposed as one of the remedies for reducing Short Channel Effects (SCE's) with the underlap being present towards the source for sub 20 nm devices. However, the Source to Drain (S/D) implant lateral diffusion leads to a variation in the effective underlap length. This paper investigates the impact of variation of straggle length on the Analog and RF parameters of the device. The RF performance is analyzed by considering the intrinsic capacitances (Cgd, Cgs), intrinsic resistances (Rgd, Rgs), transport delay (τm), inductance (Lsd), cutoff frequency (fT), and the maximum frequency of oscillations (fmax). The circuit performance of the devices are also studied. It is seen that the Analog and RF performances of the devices are improved by optimizing the S/D lateral straggle.

Transmit/receive 3-20 GHz 1.2 mW packaged double-pole-16-throw switching matrix for radar-based target detection

NASA Astrophysics Data System (ADS)

Azhari, Afreen; Kuwano, Yuki; Xiao, Xia; Kikkawa, Takamaro

2018-01-01

A 3-20 GHz transmit/receive (T/R) double-pole-16-throw (DP16T) switching matrix has been developed on a printed circuit board (PCB) to control sixteen antennas in a radar-based portable breast-cancer detection system. The DP16T switch consists of four 65 nm CMOS 0.01-20 GHz double-pole-four-throw (DP4T) switches. The proposed switch increase the number of T/R combinations to 224 from the 196 of a conventional switching matrix in order to construct high-resolution images. Using this switch and a 4 × 4 slot antenna array, a 10 × 10 mm2 aluminum target was detected with an 8-GHz-center-frequency Gaussian monocycle pulse. The power consumption of the switch is only 1.2 mW. To the best of the authors’ knowledge, this is the first T/R radio frequency (RF) DP16T switching matrix, which was realized with four CMOS DP4T switches on a PCB and was measured with RF PCB connectors.

Design of RF energy harvesting platforms for power management unit with start-up circuits

NASA Astrophysics Data System (ADS)

Costanzo, Alessandra; Masotti, Diego

2013-12-01

In this contribution we discuss an unconventional rectifier design dedicated to RF energy harvesting from ultra-low sources, such as ambient RF sources which are typically of the order of few to few tens of μW. In such conditions unsuccessful results may occur if the rectenna is directly connected to its actual load since either the minimum power or the minimum activation voltage may not be simultaneously available. For this reason a double-branch rectifier topology is considered for the power management unit (PMU), instead of traditional single-branch one. The new PMU, interposed between the rectenna and application circuits, allows the system to operate with significantly lower input power with respect to the traditional solution, while preserving efficiency during steady-state power conversion.

Linear bunchers and half-frequency bunching method

NASA Astrophysics Data System (ADS)

Tang, J. Y.; Jiang, J. Z.; Shi, A. M.; Yin, Z. K.; Wang, Y. F.

2000-12-01

A new buncher system consisting of two bunchers has been designed and constructed for HIRFL injector cyclotron, working at the SFC acceleration modes of H=1 and H=3, respectively. The bunchers use saw-tooth RF waveform, but with double-gap drift tube electrodes and single-gap grid electrodes, respectively. The special merit of the design is introduction of the half-frequency bunching mode, utilizing half of the cyclotron RF frequency. With this method, a perfect longitudinal match between the injector SFC and the main cyclotron SSC has been reached theoretically, compared to the original efficiency of 50% for most cases. Detailed studies have been made concerning space charge effects, longitudinal dispersions through the yoke hole and the spiral inflector, and non-linearity in both the RF waveform and the stray electric field of electrodes.

Double-loop frequency selective surfaces for multi frequency division multiplexing in a dual reflector antenna

NASA Technical Reports Server (NTRS)

Wu, Te-Kao (Inventor)

1994-01-01

A multireflector antenna utilizes a frequency-selective surface (FSS) in a subreflector to allow signals in two different RF bands to be selectively reflected back into a main reflector and to allow signals in other RF bands to be transmitted through it to the main reflector for primary focus transmission. A first approach requires only one FSS at the subreflector which may be an array of double-square-loop conductive elements. A second approach uses two FSS's at the subreflector which may be an array of either double-square-loop (DSL) or double-ring (DR). In the case of DR elements, they may be advantageously arranged in a triangular array instead of the rectangular array for the DSL elements.

Comparison of symmetric and asymmetric double quantum well extended-cavity diode lasers for broadband passive mode-locking at 780  nm.

PubMed

Christopher, Heike; Kovalchuk, Evgeny V; Wenzel, Hans; Bugge, Frank; Weyers, Markus; Wicht, Andreas; Peters, Achim; Tränkle, Günther

2017-07-01

We present a compact, mode-locked diode laser system designed to emit a frequency comb in the wavelength range around 780 nm. We compare the mode-locking performance of symmetric and asymmetric double quantum well ridge-waveguide diode laser chips in an extended-cavity diode laser configuration. By reverse biasing a short section of the diode laser chip, passive mode-locking at 3.4 GHz is achieved. Employing an asymmetric double quantum well allows for generation of a mode-locked optical spectrum spanning more than 15 nm (full width at -20  dB) while the symmetric double quantum well device only provides a bandwidth of ∼2.7  nm (full width at -20  dB). Analysis of the RF noise characteristics of the pulse repetition rate shows an RF linewidth of about 7 kHz (full width at half-maximum) and of at most 530 Hz (full width at half-maximum) for the asymmetric and symmetric double quantum well devices, respectively. Investigation of the frequency noise power spectral density at the pulse repetition rate shows a white noise floor of approximately 2100  Hz 2 /Hz and of at most 170  Hz 2 /Hz for the diode laser employing the asymmetric and symmetric double quantum well structures, respectively. The pulse width is less than 10 ps for both devices.

Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells

PubMed Central

Wu, Wei; Wang, KaiJun; Ni, Shuang; Ye, PanPan; Yu, YiBo; Ye, Juan; Sun, LiXia

2008-01-01

Purpose The goal of this study was to investigate whether superposing of electromagnetic noise could block or attenuate DNA damage and intracellular reactive oxygen species (ROS) increase of cultured human lens epithelial cells (HLECs) induced by acute exposure to 1.8 GHz radiofrequency field (RF) of the Global System for Mobile Communications (GSM). Methods An sXc-1800 RF exposure system was used to produce a GSM signal at 1.8 GHz (217 Hz amplitude-modulated) with the specific absorption rate (SAR) of 1, 2, 3, and 4 W/kg. After 2 h of intermittent exposure, the ROS level was assessed by the fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DNA damage to HLECs was examined by alkaline comet assay and the phosphorylated form of histone variant H2AX (γH2AX) foci formation assay. Results After exposure to 1.8 GHz RF for 2 h, HLECs exhibited significant intracellular ROS increase in the 2, 3, and 4 W/kg groups. RF radiation at the SAR of 3 W/kg and 4 W/kg could induce significant DNA damage, examined by alkaline comet assay, which was used to detect mainly single strand breaks (SSBs), while no statistical difference in double strand breaks (DSBs), evaluated by γH2AX foci, was found between RF exposure (SAR: 3 and 4 W/kg) and sham exposure groups. When RF was superposed with 2 μT electromagnetic noise could block RF-induced ROS increase and DNA damage. Conclusions DNA damage induced by 1.8 GHz radiofrequency field for 2 h, which was mainly SSBs, may be associated with the increased ROS production. Electromagnetic noise could block RF-induced ROS formation and DNA damage. PMID:18509546

Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells.

PubMed

Yao, Ke; Wu, Wei; Wang, KaiJun; Ni, Shuang; Ye, PanPan; Yu, YiBo; Ye, Juan; Sun, LiXia

2008-05-19

The goal of this study was to investigate whether superposing of electromagnetic noise could block or attenuate DNA damage and intracellular reactive oxygen species (ROS) increase of cultured human lens epithelial cells (HLECs) induced by acute exposure to 1.8 GHz radiofrequency field (RF) of the Global System for Mobile Communications (GSM). An sXc-1800 RF exposure system was used to produce a GSM signal at 1.8 GHz (217 Hz amplitude-modulated) with the specific absorption rate (SAR) of 1, 2, 3, and 4 W/kg. After 2 h of intermittent exposure, the ROS level was assessed by the fluorescent probe, 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). DNA damage to HLECs was examined by alkaline comet assay and the phosphorylated form of histone variant H2AX (gammaH2AX) foci formation assay. After exposure to 1.8 GHz RF for 2 h, HLECs exhibited significant intracellular ROS increase in the 2, 3, and 4 W/kg groups. RF radiation at the SAR of 3 W/kg and 4 W/kg could induce significant DNA damage, examined by alkaline comet assay, which was used to detect mainly single strand breaks (SSBs), while no statistical difference in double strand breaks (DSBs), evaluated by gammaH2AX foci, was found between RF exposure (SAR: 3 and 4 W/kg) and sham exposure groups. When RF was superposed with 2 muT electromagnetic noise could block RF-induced ROS increase and DNA damage. DNA damage induced by 1.8 GHz radiofrequency field for 2 h, which was mainly SSBs, may be associated with the increased ROS production. Electromagnetic noise could block RF-induced ROS formation and DNA damage.

Preparation of Double-Stranded (Replicative Form) Bacteriophage M13 DNA.

PubMed

Green, Michael R; Sambrook, Joseph

2017-11-01

The double-stranded, closed-circular, replicative form (RF) of M13 DNA is present in high copy numbers in infected cells, and its physical characteristics are essentially identical to those of closed-circular plasmid DNAs. Any of the methods commonly used to purify plasmid DNA can therefore be used to isolate M13 RF DNA. This protocol describes the isolation of M13 RF DNA by alkaline lysis from small volumes (1-2 mL) of infected bacterial cultures. The yield of DNA (1-4 mg, depending on the size of the M13 clone) is more than enough for most purposes in molecular cloning. However, should more DNA be needed, the procedure can easily be scaled up. © 2017 Cold Spring Harbor Laboratory Press.

Broadband excitation in nuclear magnetic resonance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tycko, Robert

1984-10-01

Theoretical methods for designing sequences of radio frequency (rf) radiation pulses for broadband excitation of spin systems in nuclear magnetic resonance (NMR) are described. The sequences excite spins uniformly over large ranges of resonant frequencies arising from static magnetic field inhomogeneity, chemical shift differences, or spin couplings, or over large ranges of rf field amplitudes. Specific sequences for creating a population inversion or transverse magnetization are derived and demonstrated experimentally in liquid and solid state NMR. One approach to broadband excitation is based on principles of coherent averaging theory. A general formalism for deriving pulse sequences is given, along withmore » computational methods for specific cases. This approach leads to sequences that produce strictly constant transformations of a spin system. The importance of this feature in NMR applications is discussed. A second approach to broadband excitation makes use of iterative schemes, i.e. sets of operations that are applied repetitively to a given initial pulse sequences, generating a series of increasingly complex sequences with increasingly desirable properties. A general mathematical framework for analyzing iterative schemes is developed. An iterative scheme is treated as a function that acts on a space of operators corresponding to the transformations produced by all possible pulse sequences. The fixed points of the function and the stability of the fixed points are shown to determine the essential behavior of the scheme. Iterative schemes for broadband population inversion are treated in detail. Algebraic and numerical methods for performing the mathematical analysis are presented. Two additional topics are treated. The first is the construction of sequences for uniform excitation of double-quantum coherence and for uniform polarization transfer over a range of spin couplings. Double-quantum excitation sequences are demonstrated in a liquid crystal system. The second additional topic is the construction of iterative schemes for narrowband population inversion. The use of sequences that invert spin populations only over a narrow range of rf field amplitudes to spatially localize NMR signals in an rf field gradient is discussed.« less

Does acute radio-frequency electromagnetic field exposure affect visual event-related potentials in healthy adults?

PubMed

Dalecki, Anna; Loughran, Sarah P; Verrender, Adam; Burdon, Catriona A; Taylor, Nigel A S; Croft, Rodney J

2018-05-01

To use improved methods to address the question of whether acute exposure to radio-frequency (RF) electromagnetic fields (RF-EMF) affects early (80-200 ms) sensory and later (180-600 ms) cognitive processes as indexed by event-related potentials (ERPs). Thirty-six healthy subjects completed a visual discrimination task during concurrent exposure to a Global System for Mobile Communications (GSM)-like, 920 MHz signal with peak-spatial specific absorption rate for 10 g of tissue of 0 W/kg of body mass (Sham), 1 W/kg (Low RF) and 2 W/kg (High RF). A fully randomised, counterbalanced, double-blind design was used. P1 amplitude was reduced (p = .02) and anterior N1 latency was increased (p = .04) during Exposure compared to Sham. There were no effects on any other ERP latencies or amplitudes. RF-EMF exposure may affect early perceptual (P1) and preparatory motor (anterior N1) processes. However, only two ERP indices, out of 56 comparisons, were observed to differ between RF-EMF exposure and Sham, suggesting that these observations may be due to chance. These observations are consistent with previous findings that RF-EMF exposure has no reliable impact on cognition (e.g., accuracy and response speed). Copyright © 2018 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Specific interaction of the nonstructural protein NS1 of minute virus of mice (MVM) with [ACCA](2) motifs in the centre of the right-end MVM DNA palindrome induces hairpin-primed viral DNA replication.

PubMed

Willwand, Kurt; Moroianu, Adela; Hörlein, Rita; Stremmel, Wolfgang; Rommelaere, Jean

2002-07-01

The linear single-stranded DNA genome of minute virus of mice (MVM) is replicated via a double-stranded replicative form (RF) intermediate DNA. Amplification of viral RF DNA requires the structural transition of the right-end palindrome from a linear duplex into a double-hairpin structure, which serves for the repriming of unidirectional DNA synthesis. This conformational transition was found previously to be induced by the MVM nonstructural protein NS1. Elimination of the cognate NS1-binding sites, [ACCA](2), from the central region of the right-end palindrome next to the axis of symmetry was shown to markedly reduce the efficiency of hairpin-primed DNA replication, as measured in a reconstituted in vitro replication system. Thus, [ACCA](2) sequence motifs are essential as NS1-binding elements in the context of the structural transition of the right-end MVM palindrome.

Double-quantum homonuclear correlations of spin I=5/2 nuclei.

PubMed

Iuga, Dinu

2011-02-01

The challenges associated with acquiring double-quantum homonuclear Nuclear Magnetic Resonance correlation spectra of half-integer quadrupolar nuclei are described. In these experiments the radio-frequency irradiation amplitude is necessarily weak in order to selectively excite the central transition. In this limit only one out of the 25 double-quantum coherences possible for two coupled spin I=5/2 nuclei is excited. An investigation of all the 25 two spins double quantum transitions reveals interesting effects such as a compensation of the first-order quadrupolar interaction between the two single quantum transitions involved in the double quantum coherence. In this paper a full numerical study of a hypothetical two spin I=5/2 system is used to show what happens when the RF amplitude during recoupling is increased. In principle this is advantageous, since the required double quantum coherence should build up faster, but in practice it also induces adiabatic passage transfer of population and coherence which impedes any build up. Finally an optimized rotary resonance recoupling (oR(3)) sequence is introduced in order to decrease these transfers. This sequence consists of a spin locking irradiation whose amplitude is reduced four times during one rotor period, and allows higher RF powers to be used during recoupling. The sequence is used to measure (27)Al DQ dipolar correlation spectra of Y(3)Al(5)O(12) (YAG) and gamma alumina (γAl(2)O(3)). The results prove that aluminium vacancies in gamma alumina mainly occur in the tetrahedral sites. Copyright © 2010 Elsevier Inc. All rights reserved.

Single-shot readout of accumulation mode Si/SiGe spin qubits using RF reflectometry

NASA Astrophysics Data System (ADS)

Volk, Christian; Martins, Frederico; Malinowski, Filip; Marcus, Charles M.; Kuemmeth, Ferdinand

Spin qubits based on gate-defined quantum dots are promising systems for realizing quantum computation. Due to their low concentration of nuclear-spin-carrying isotopes, Si/SiGe heterostructures are of particular interest. While high fidelities have been reported for single-qubit and two-qubit gate operations, qubit initialization and measurement times are relatively slow. In order to develop fast read-out techniques compatible with the operation of spin qubits, we characterize double and triple quantum dots confined in undoped Si/Si0.7Ge0.3 heterostructures using accumulation and depletion gates and a nearby RF charge sensor dot. We implement a RF reflectometry technique that allows single-shot charge read-out at integration times on the order of a few μs. We show our recent advancement towards implementing spin qubits in these structures, including spin-selective single-shot read-out.

Ultra-wideband microwave photonic link based on single-sideband modulation

NASA Astrophysics Data System (ADS)

Li, Jingnan; Wang, Yunxin; Wang, Dayong; Zhou, Tao; Zhong, Xin; Xu, Jiahao; Yang, Dengcai; Rong, Lu

2017-10-01

Comparing with the conventional double-sideband (DSB) modulation in communication system, single-sideband (SSB) modulation only demands half bandwidth of DSB in transmission. Two common ways are employed to implement SSB modulation by using optical filter (OF) or electrical 90° phase shift, respectively. However, the bandwidth of above methods is limited by characteristics of current OF and electrical phase shift. To overcome this problem, an ultra-wideband microwave photonic link based on SSB modulation is proposed and demonstrated. The radio frequency (RF) signal modulates a single-drive dual-parallel Mach-Zehnder modulator, and the SSB modulation is realized by combining an electrical 90° hybrid coupler and an optical bandpass filter. The experimental results indicate that the system can achieve SSB modulation for RF signal from 2 to 40 GHz. The proposed microwave photonic link provides an ultra-wideband approach based on SSB modulation for radio-over-fiber system.

Development of high-efficiency power amplifiers for PIP2 (Project X), Phase II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raab, Frederick

The Fermi Lab PIP II (formerly Project X) accelerator will require the generation of over a megawatt of radio-frequency (RF) power at 325 and 650 MHz. This Phase-II SBIR grant developed techniques to generate this RF power efficienly. The basis of this approach is a system comprising high-efficiency RF power amplifiers, high-efficiency class-S modulators to maintain efficiency at all power levels, and low-loss power combiners. A digital signal processor adjusts signal parameters to obtain the maximum efficiency while producing a signal of the desired amplitude and phase. Components of 4-kW prototypes were designed, assembled, and tested. The 500-W modules producemore » signals at 325 MHz with an overall efficiency of 83 percent and signals at 650 MHz with an overall efficiency of 79 percent. This efficiency is nearly double that available from conventional techniques, which makes it possible to cut the power consumption nearly in half. The system is designed to be scalable to the multi-kilowatt level and can be adapted to other DoE applications.« less

A dual-stimuli-responsive fluorescent switch ultrathin film

NASA Astrophysics Data System (ADS)

Li, Zhixiong; Liang, Ruizheng; Liu, Wendi; Yan, Dongpeng; Wei, Min

2015-10-01

Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP@PTBEM and Rf-PSS with cationic layered double hydroxide (LDH) nanoplatelets to obtain the (Rf-PSS/LDH/SP@PTBEM)n UTFs (n: bilayer number). The assembly process of the UTFs and their luminescence properties, as monitored by fluorescence spectroscopy and scanning electron microscopy (SEM), present a uniform and ordered layered structure with stepwise growth. The resulting Rf-PSS/LDH/SP@PTBEM UTF serves as a three-state switchable multicolor (green, yellow, and red) luminescent system based on stimulation from UV/Vis light and pH, with an acceptable reversibility. Therefore, this work provides a facile way to fabricate stimuli-responsive solid-state film switches with tunable-color luminescence, which have potential applications in the areas of displays, sensors, and rewritable optical memory and fluorescent logic devices.Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP@PTBEM and Rf-PSS with cationic layered double hydroxide (LDH) nanoplatelets to obtain the (Rf-PSS/LDH/SP@PTBEM)n UTFs (n: bilayer number). The assembly process of the UTFs and their luminescence properties, as monitored by fluorescence spectroscopy and scanning electron microscopy (SEM), present a uniform and ordered layered structure with stepwise growth. The resulting Rf-PSS/LDH/SP@PTBEM UTF serves as a three-state switchable multicolor (green, yellow, and red) luminescent system based on stimulation from UV/Vis light and pH, with an acceptable reversibility. Therefore, this work provides a facile way to fabricate stimuli-responsive solid-state film switches with tunable-color luminescence, which have potential applications in the areas of displays, sensors, and rewritable optical memory and fluorescent logic devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05376e

Crossed-coil detection of two-photon excited nuclear quadrupole resonance

NASA Astrophysics Data System (ADS)

Eles, Philip T.; Michal, Carl A.

2005-08-01

Applying a recently developed theoretical framework for determining two-photon excitation Hamiltonians using average Hamiltonian theory, we calculate the excitation produced by half-resonant irradiation of the pure quadrupole resonance of a spin-3/2 system. This formalism provides expressions for the single-quantum and double-quantum nutation frequencies as well as the Bloch-Siegert shift. The dependence of the excitation strength on RF field orientation and the appearance of the free-induction signal along an axis perpendicular to the excitation field provide an unmistakable signature of two-photon excitation. We demonstrate single- and double-quantum excitation in an axially symmetric system using 35Cl in a single crystal of potassium chlorate ( ωQ = 28 MHz) with crossed-coil detection. A rotation plot verifies the orientation dependence of the two-photon excitation, and double-quantum coherences are observed directly with the application of a static external magnetic field.

rf traveling-wave electron gun for photoinjectors

NASA Astrophysics Data System (ADS)

Schaer, Mattia; Citterio, Alessandro; Craievich, Paolo; Reiche, Sven; Stingelin, Lukas; Zennaro, Riccardo

2016-07-01

The design of a photoinjector, in particular that of the electron source, is of central importance for free electron laser (FEL) machines where a high beam brightness is required. In comparison to standard designs, an rf traveling-wave photocathode gun can provide a more rigid beam with a higher brightness and a shorter pulse. This is illustrated by applying a specific optimization procedure to the SwissFEL photoinjector, for which a brightness improvement up to a factor 3 could be achieved together with a double gun output energy compared to the reference setup foreseeing a state-of-the-art S-band rf standing-wave gun. The higher brightness is mainly given by a (at least) double peak current at the exit of the gun which brings benefits for both the beam dynamics in the linac and the efficiency of the FEL process. The gun design foresees an innovative coaxial rf coupling at both ends of the structure which allows a solenoid with integrated bucking coil to be placed around the cathode in order to provide the necessary focusing right after emission.

MR Coagulation: A Novel Minimally Invasive Approach to Aneurysm Repair.

PubMed

Cohen, Ouri; Zhao, Ming; Nevo, Erez; Ackerman, Jerome L

2017-11-01

To demonstrate a proof of concept of magnetic resonance (MR) coagulation, in which MR imaging scanner-induced radiofrequency (RF) heating at the end of an intracatheter long wire heats and coagulates a protein solution to effect a vascular repair by embolization. MR coagulation was simulated by finite-element modeling of electromagnetic fields and specific absorption rate (SAR) in a phantom. A glass phantom consisting of a spherical cavity joined to the side of a tube was incorporated into a flow system to simulate an aneurysm and flowing blood with velocities of 0-1.7 mL/s. A double-lumen catheter containing the wire and fiberoptic temperature sensor in 1 lumen was passed through the flow system into the aneurysm, and 9 cm 3 of protein solution was injected into the aneurysm through the second lumen. The distal end of the wire was laid on the patient table as an antenna to couple RF from the body coil or was connected to a separate tuned RF pickup coil. A high RF duty-cycle turbo spin-echo pulse sequence excited the wire such that RF energy deposited at the tip of the wire coagulated the protein solution, embolizing the aneurysm. The protein coagulation temperature of 60°C was reached in the aneurysm in ∼12 seconds, yielding a coagulated mass that largely filled the aneurysm. The heating rate was controlled by adjusting pulse-sequence parameters. MR coagulation has the potential to embolize vascular defects by coagulating a protein solution delivered by catheter using MR imaging scanner-induced RF heating of an intracatheter wire. Copyright © 2017 SIR. Published by Elsevier Inc. All rights reserved.

Impact of underlap and mole-fraction on RF performance of strained-Si/Si1-xGex/strained-Si DG MOSFETs

NASA Astrophysics Data System (ADS)

Dutta, Arka; Koley, Kalyan; Sarkar, Chandan K.

2014-11-01

In this paper, a systematic RF performance analysis of double-gate strained silicon (DGSS) nMOSFETs is presented. The analysis is focused upon impact of Germanium mole-fraction variation on RF performance of underlap engineered DGSS nMOSFET. The RF performance of the device is analysed as a function of intrinsic RF figure of merits (FOMs) including non-quasi static effects (NQS). The RF FOMs are represented by the intrinsic gate to source/drain capacitance (Cgs and Cgd) and resistance (Rgs and Rgd), the transport delay (τm), the intrinsic inductance (Lsd), the cut-off frequency (fT), and the maximum oscillation frequency (fMAX). The results of the study suggested a significant improvement in the device performance, up to 40% increase in Germanium mole fraction (χ).

Radio-frequency low-coherence interferometry.

PubMed

Fernández-Pousa, Carlos R; Mora, José; Maestre, Haroldo; Corral, Pablo

2014-06-15

A method for retrieving low-coherence interferograms, based on the use of a microwave photonics filter, is proposed and demonstrated. The method is equivalent to the double-interferometer technique, with the scanning interferometer replaced by an analog fiber-optics link and the visibility recorded as the amplitude of its radio-frequency (RF) response. As a low-coherence interferometry system, it shows a decrease of resolution induced by the fiber's third-order dispersion (β3). As a displacement sensor, it provides highly linear and slope-scalable readouts of the interferometer's optical path difference in terms of RF, even in the presence of third-order dispersion. In a proof-of-concept experiment, we demonstrate 20-μm displacement readouts using C-band EDFA sources and standard single-mode fiber.

Double and triple-harmonic RF buckets and their use for bunch squeezing in AGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gardner, C. J.

2016-08-24

For the past several years we have merged bunches in AGS in order to achieve the desired intensity per bunch prior to injection into RHIC. The merging is done on a flat porch at or above AGS injection energy. Because the merges involve the reduction of the RF harmonic number by a factor of 2 (for a 2 to 1 merge) and then a factor of 3 (for a 3 to 1 merge), one requires RF frequencies 6hf s, 3hf s, 2hf s and hf s, where f s is the revolution frequency on the porch and h = 4more » is the fundamental harmonic number. The standard AGS RF cavities cannot operate at the lowest frequencies 2hf s and hf s; these are provided by two modified cavities. Upon completion of the merges, the bunches are sitting in harmonic h buckets. In order to be accelerated they need to be squeezed into harmonic 3h buckets. This is accomplished by producing a double-harmonic bucket in which harmonics h and 2h act in concert, and then a triple-harmonic bucket in which harmonics h, 2h, and 3h act in concert. Simulations have shown that the squeeze presents an acceptance bottleneck which limits the longitudinal emittance that can be put into the harmonic 3h bucket. In this note the areas of the double and triple-harmonic buckets are calculated explicitly, and it is shown that these go through a minimum as the RF voltages are raised to the desired values. Several RF voltage ranges are examined, and the acceptance bottleneck is determined for each of these. Finally, the acceptance bottleneck for Au77+ bunches in AGS is calculated for several RF voltage ranges. The main result is that the RF voltages for the low-frequency harmonic h and 2h cavities both must be at least 22 kV in order to achieve an acceptance of 0:6 eV s per nucleon. If the harmonic h and 2h voltages are 15 and 22 kV, respectively, then the acceptance is reduced to 0:548 eV s per nucleon.« less

Design of RF MEMS switches without pull-in instability

NASA Astrophysics Data System (ADS)

Proctor, W. Cyrus; Richards, Gregory P.; Shen, Chongyi; Skorczewski, Tyler; Wang, Min; Zhang, Jingyan; Zhong, Peng; Massad, Jordan E.; Smith, Ralph

2010-04-01

Micro-electro-mechanical systems (MEMS) switches for radio-frequency (RF) signals have certain advantages over solid-state switches, such as lower insertion loss, higher isolation, and lower static power dissipation. Mechanical dynamics can be a determining factor for the reliability of RF MEMS. The RF MEMS ohmic switch discussed in this paper consists of a plate suspended over an actuation pad by four double-cantilever springs. Closing the switch with a simple step actuation voltage typically causes the plate to rebound from its electrical contacts. The rebound interrupts the signal continuity and degrades the performance, reliability and durability of the switch. The switching dynamics are complicated by a nonlinear, electrostatic pull-in instability that causes high accelerations. Slow actuation and tailored voltage control signals can mitigate switch bouncing and effects of the pull-in instability; however, slow switching speed and overly-complex input signals can significantly penalize overall system-level performance. Examination of a balanced and optimized alternative switching solution is sought. A step toward one solution is to consider a pull-in-free switch design. In this paper, determine how simple RC-circuit drive signals and particular structural properties influence the mechanical dynamics of an RF MEMS switch designed without a pull-in instability. The approach is to develop a validated modeling capability and subsequently study switch behavior for variable drive signals and switch design parameters. In support of project development, specifiable design parameters and constraints will be provided. Moreover, transient data of RF MEMS switches from laser Doppler velocimetry will be provided for model validation tasks. Analysis showed that a RF MEMS switch could feasibly be designed with a single pulse waveform and no pull-in instability and achieve comparable results to previous waveform designs. The switch design could reliably close in a timely manner, with small contact velocity, usually with little to no rebound even when considering manufacturing variability.

Estimation of chemical carcass composition from 8th rib characteristics with Belgian blue double-muscled bulls.

PubMed

De Campeneere, S; Fiems, L O; Van de Voorde, G; Vanacker, J M; Boucque, C V; Demeyer, D I

1999-01-01

Characteristics from the 8th rib cut: chemical composition, tissue composition after dissection, specific gravity (SG) and m. longissimus thoracis (LT) composition, collected on 17 Belgian Blue double-muscled fattening bulls were used to generate equations for predicting chemical carcass composition. Carcass composition was best predicted from chemical analysis of the 8th rib cut and the empty body weight (EBW) of the bull. Carcass chemical fat content (CCF, kg) was predicted from the 8th rib cut fat content (ether extract, 8RF, kg) by the following regression: CCF=1.94+27.37 8RF (R(2)=0.957, RSD =9.89%). A higher coefficient was found for carcass water (CCW, kg) predicted from 8RF and EBW: CCW=-2.26+0.28 EBW-34.28 8RF (R(2)=0.997, RSD=1.48%). No parameter was found to improve the prediction of CCP from EBW solely: CCP=-0.86+0.08 EBW (R(2) =0.992, RSD=2.61%). Prediction equations based solely on LT composition had low R(2) values of between 0.38 and 0.67, whereas no significant equations were found using SG. However, equations based on EBW had R(2) values between 0.78 and 0.99. Chemical components of the 8th rib cut in combination with EBW are most useful in predicting the chemical composition of the carcass of Belgian-Blue double-muscled bulls.

Water consumption, grain yield, and water productivity in response to field water management in double rice systems in China.

PubMed

Wu, Xiao Hong; Wang, Wei; Yin, Chun Mei; Hou, Hai Jun; Xie, Ke Jun; Xie, Xiao Li

2017-01-01

Rice cultivation has been challenged by increasing food demand and water scarcity. We examined the responses of water use, grain yield, and water productivity to various modes of field water managements in Chinese double rice systems. Four treatments were studied in a long-term field experiment (1998-2015): continuous flooding (CF), flooding-midseason drying-flooding (F-D-F), flooding-midseason drying-intermittent irrigation without obvious standing water (F-D-S), and flooding-rain-fed (F-RF). The average precipitation was 483 mm in early-rice season and 397 mm in late-rice season. The irrigated water for CF, F-D-F, F-D-S, and F-RF, respectively, was 263, 340, 279, and 170 mm in early-rice season, and 484, 528, 422, and 206 mm in late-rice season. Grain yield for CF, F-D-F, F-D-S, and F-RF, respectively, was 4,722, 4,597, 4,479, and 4,232 kgha-1 in early-rice season, and 5,420, 5,402, 5,366, and 4,498 kgha-1 in late-rice season. Compared with CF, F-D-F consumed more irrigated water, which still decreased grain yield, leading to a decrease in water productivity by 25% in early-rice season and by 8% in late-rice season. Compared with F-D-F, F-D-S saved much irrigated water with a small yield reduction, leading to an increase in water productivity by 22% in early-rice season and by 26% in late-rice season. The results indicate that CF is best for early-rice and FDS is best for late-rice in terms of grain yield and water productivity.

Rheumatoid factor and anti-citrullinated protein antibody positivity, but not level, are associated with increased mortality in patients with rheumatoid arthritis: results from two large independent cohorts.

PubMed

Humphreys, Jennifer H; van Nies, Jessica A B; Chipping, Jackie; Marshall, Tarnya; van der Helm-van Mil, Annette H M; Symmons, Deborah P M; Verstappen, Suzanne M M

2014-12-04

This study aimed to investigate rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) status and levels as predictors of mortality in two large cohorts of patients with early inflammatory arthritis (EIA). Data from the Norfolk Arthritis Register (NOAR) and Leiden Early Arthritis Clinic (EAC) cohorts were used. At baseline, patients had demographic data and smoking status recorded; RF, ACPA and inflammatory markers were measured in the local laboratories. Patients were flagged with national death registers until death or censor date. Antibody status was stratified as negative, low or high positive by RF and ACPA levels individually. In addition, patients were grouped as seronegative, RF positive, ACPA positive or double antibody (RF and ACPA) positive. Cox regression models explored associations between antibody status and mortality adjusting for age, sex, smoking status, inflammatory markers and year of enrolment. A total of 4962 patients were included, 64% were female. Median age at onset was 56 (NOAR) and 54 (EAC) years. In NOAR and EAC respectively, 35% and 42% of patients were ACPA/RF positive. When antibody status was stratified as negative, low or high positive, there were no consistent findings between the two cohorts. Double antibody positivity was associated with excess mortality in both cohorts compared to seronegative patients: NOAR and EAC respective adjusted HR (95% confidence interval) 1.35 (1.09 to 1.68) and 1.58 (1.16 to 2.15). Patients with EIA who are seropositive for both RF and ACPA have increased mortality compared to those who are single positive or seronegative. Antibody level in seropositive patients was not consistently associated with excess mortality.

B1 transmit phase gradient coil for single-axis TRASE RF encoding.

PubMed

Deng, Qunli; King, Scott B; Volotovskyy, Vyacheslav; Tomanek, Boguslaw; Sharp, Jonathan C

2013-07-01

TRASE (Transmit Array Spatial Encoding) MRI uses RF transmit phase gradients instead of B0 field gradients for k-space traversal and high-resolution MR image formation. Transmit coil performance is a key determinant of TRASE image quality. The purpose of this work is to design an optimized RF transmit phase gradient array for spatial encoding in a transverse direction (x- or y- axis) for a 0.2T vertical B0 field MRI system, using a single transmitter channel. This requires the generation of two transmit B1 RF fields with uniform amplitude and positive and negative linear phase gradients respectively over the imaging volume. A two-element array consisting of a double Maxwell-type coil and a Helmholtz-type coil was designed using 3D field simulations. The phase gradient polarity is set by the relative phase of the RF signals driving the simultaneously energized elements. Field mapping and 1D TRASE imaging experiments confirmed that the constructed coil produced the fields and operated as designed. A substantially larger imaging volume relative to that obtainable from a non-optimized Maxwell-Helmholtz design was achieved. The Maxwell (sine)-Helmholtz (cosine) approach has proven successful for a horizontal phase gradient coil. A similar approach may be useful for other phase-gradient coil designs. Copyright © 2013 Elsevier Inc. All rights reserved.

Simulations of 'decoherence' with noise pulses

NASA Astrophysics Data System (ADS)

Stodolsky, L.

A simulation of decoherence as random noise in the Hamiltonian is studied. The full Hamiltonian for the rf Squid is used, with the parameters chosen such that there is a double-potential well configuration where the two quasi-degenerate lowest levels are well separated from the rest. The results for these first two levels are in quantitative agreement with expectations from the 'spin 1/2' picture for the behaviour of a two-state system.

A homonuclear spin-pair filter for solid-state NMR based on adiabatic-passage techniques

NASA Astrophysics Data System (ADS)

Verel, René; Baldus, Marc; Ernst, Matthias; Meier, Beat H.

1998-05-01

A filtering scheme for the selection of spin pairs (and larger spin clusters) under fast magic-angle spinning is proposed. The scheme exploits the avoided level crossing in spin pairs during an adiabatic amplitude sweep through the so-called HORROR recoupling condition. The advantages over presently used double-quantum filters are twofold. (i) The maximum theoretical filter efficiency is, due to the adiabatic variation, 100% instead of 73% as for transient methods. (ii) Since the filter does not rely on the phase-cycling properties of the double-quantum coherence, there is no need to obtain the full double-quantum intensity for all spins in the sample at one single point in time. The only important requirement is that all coupled spins pass through a two-spin state during the amplitude sweep. This makes the pulse scheme robust with respect to rf-amplitude missetting, rf-field inhomogeneity and chemical-shift offset.

Multiplexed HTS rf SQUID magnetometer array for eddy current testing of aircraft rivet joints

NASA Astrophysics Data System (ADS)

Gärtner, S.; Krause, H.-J.; Wolters, N.; Lomparski, D.; Wolf, W.; Schubert, J.; Kreutzbruck, M. v.; Allweins, K.

2002-05-01

Using three rf SQUID magnetometers, a multiplexed SQUID array was implemented. The SQUIDs are positioned in line with 7 mm spacing and operated using one feedback electronics with sequential read out demodulation at different radio frequencies (rf). The cross-talk between SQUID channels was determined to be negligible. To show the performance of the SQUID array, eddy current (EC) measurements of aluminum aircraft samples in conjunction with a differential (double-D) EC excitation and lock-in readout were carried out. With computer-controlled continuous switching of the SQUIDs during the scan, three EC signal traces of the sample are obtained simultaneously. We performed measurements with an EC excitation frequency of 135 Hz to localize an artificial crack (sawcut flaw) of 20 mm length in an aluminum sheet with 0.6 mm thickness. The flaw was still detected when covered with aluminum of up to 10 mm thickness. In addition, measurements with varying angles between scanning direction and flaw orientation are presented.

Application of Double Spin-Echo Spiral Chemical Shift Imaging to Rapid Metabolic Mapping of Hyperpolarized [1-13C]-Pyruvate

PubMed Central

Josan, Sonal; Yen, Yi-Fen; Hurd, Ralph; Pfefferbaum, Adolf; Spielman, Daniel; Mayer, Dirk

2011-01-01

Undersampled spiral CSI (spCSI) using a free induction decay (FID) acquisition allows sub-second metabolic imaging of hyperpolarized 13C. Phase correction of the FID acquisition can be difficult, especially with contributions from aliased out-of-phase peaks. This work extends the spCSI sequence by incorporating double spin-echo radiofrequency (RF) pulses to eliminate the need for phase correction and obtain high quality spectra in magnitude mode. The sequence also provides an added benefit of attenuating signal from flowing spins, which can otherwise contaminate signal in the organ of interest. The refocusing pulses can potentially lead to a loss of hyperpolarized magnetization in dynamic imaging due to flow of spins through the fringe field of the RF coil, where the refocusing pulses fail to provide complete refocusing. Care must be taken for dynamic imaging to ensure that the spins remain within the B1-homogeneous sensitive volume of the RF coil. PMID:21316280

Growth of the parvovirus minute virus of mice MVMp3 in EL4 lymphocytes is restricted after cell entry and before viral DNA amplification: cell-specific differences in virus uncoating in vitro.

PubMed

Previsani, N; Fontana, S; Hirt, B; Beard, P

1997-10-01

Two murine parvoviruses with genomic sequences differing only in 33 nucleotides (8 amino acids) in the region coding for the capsid proteins show different host cell specificities: MVMi grows in EL4 T lymphocytes and MVMp3 grows in A9 fibroblasts. In this study we compared the courses of infections with these two viruses in EL4 cells in order to investigate at which step(s) the infection process of MVMp3 is interrupted. The two viruses bound equally well to EL4 cells, and similar amounts of MVMi and MVMp3 input virion DNA appeared in the nuclear fractions of EL4 cells 1 h after infection. However, double-stranded replicative-form (RF) DNA of the two viruses appeared at different times, at 10 h postinfection with MVMi and at 24 h postinfection with MVMp3. The amount of MVMp3 RF DNA detected at 24 h was very small because it was produced only in a tiny subset of the population of EL4 cells that proved to be permissive for MVMp3. Replication of double-stranded viral DNA in EL4 cells was measured after transfection of purified RF DNA, cloned viral DNA, and cloned viral DNA with a mutation preventing synthesis of the capsid proteins. In each of these cases, DNA replication was comparable for MVMi and MVMp3. Production of virus particles also appeared to be similar after transfection of the two types of RF DNA into EL4 cells. Conversion of incoming 32P-labeled single-stranded MVM DNA to 32P-labeled double-stranded RF DNA was detected only after RF DNA amplification, indicating that few molecules serve as templates for viral DNA amplification. We showed that extracts of EL4 cells contain a factor which can destabilize MVMi virions but not MVMp3 by testing the sensitivity of viral DNA to DNase and by CsCl gradient analyses of viral particles. We therefore conclude that the MVMp3 life cycle is arrested after the transport of virions to the nucleus and prior to the replication of RF DNA, most likely at the stage of viral decapsidation.

The effect of radio-frequency self bias on ion acceleration in expanding argon plasmas in helicon sources

NASA Astrophysics Data System (ADS)

Wiebold, Matthew D.

Time-averaged plasma potential differences up to ˜ 165 V over several hundred Debye lengths are observed in low pressure (pn < 1 mTorr) expanding argon plasmas in the Madison Helicon Experiment. The potential gradient leads to ion acceleration exceeding Ei ≈ 7 kTe in some cases. Up to 1 kW of 13.56 MHz RF power is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field up to 1 kG. An RPA measures the IEDF and an emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, are identified by jumps in electron density as RF power is increased. In the capacitive mode, large fluctuations of the plasma potential (Vp--p ≳ 140 V, Vp--p/Vp ≈ 150%) exist at the RF frequency, leading to formation of a self-bias voltage. The mobile electrons can flow from the upstream region during an RF cycle whereas ions cannot, leading to an initial imbalance of flux, and the self-bias voltage builds as a result. The plasma potential in the expansion chamber is held near the floating potential for argon (Vp ≈ 5kTe/e). In the capacitive mode, the ion acceleration is not well described by an ambipolar relation. The accelerated population decay is consistent with that predicted by charge-exchange collisions. Grounding the upstream endplate increases the self-bias voltage compared to a floating endplate. In the inductive and helicon modes, the ion acceleration more closely follows an ambipolar relation, a result of decreased capacitive coupling due to the decreased RF skin depth. The scaling of the potential gradient with the argon flow rate, magnetic field and RF power are investigated, with the highest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees well with that predicted for RF sheaths. Use of the self-bias effect in a plasma thruster is explored, possibly for a low thrust, high specific impulse mode in a multi-mode helicon thruster. This work could also explain similar potential gradients in expanding helicon plasmas that are ascribed to double layer formation in the literature.

Investigation of Noise in Photonic Links and Components

DTIC Science & Technology

2017-10-24

radio-frequency (RF) domain were studied : double Rayleigh scattering-induced relative intensity noise and component-induced phase noise. Techniques to...oscillators were built and characterized, one of which incorporated a method to potentially minimize close-in RF phase noise that entailed using the...phase noise impressed on one continuous-wave laser wavelength to cancel that impressed on another. 24-10-2017 Memorandum Office of Naval Research One

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mutic, S; Low, D; Chmielewski, T

Purpose: To describe the design and characteristics of a novel linac-based MRI guided radiation therapy system that addresses RF and magnetic field interference and that can be housed in conventional radiotherapy vaults. Methods: The MR-IGRT system will provide simultaneous MR imaging combined with both simple (3D) and complex (IMRT, SBRT, SRS) techniques. The system is a combination of a) double-donut split solenoidal superconducting 0.345T MRI; and b) a 90 cm isocenter ring-gantry mounted 6MV, flattening filter-free linac coupled with a stacked doubly-focused multileaf collimator with 4 mm resolution. A novel RF shielding and absorption technology was developed to isolate themore » beam generating RF emissions from the MR, while a novel magnetic shielding sleeve system was developed to place the magnetic field-sensitive components in low-magnetic field regions. The system design produces high spatial resolution radiation beams with state-of-the art radiation dose characteristics and simultaneous MR imaging. Results: Prototype testing with a spectrum analyzer has demonstrated complete elimination of linac RF inside the treatment room. The magnetic field inside of the magnetic shielding was well below the specification, allowing the linear accelerator to operate normally. A novel on-gantry shimming system maintained < 25 ppm magnetic field homogeneity over a 45 cm spherical field of view for all gantry angles. Conclusion: The system design demonstrates the feasibility coupling a state-of-the art linac system with a 0.345T MRI, enabling highly conformal radiation therapy with simultaneous MR image guidance. S. Mutic’s employer (Washington University) has grant with ViewRay; D. Low is former ViewRay scientific advisory board member (ended October 2015); T. Chmielewski, G. Fought, M. Hernandez, I. Kawrakow, A. Sharma, S. Shvartsman, J. Dempsey are employees of ViewRay with stock options (Dempsey has leadership role and Dempsey/Kawrakow have stock).« less

A dual-stimuli-responsive fluorescent switch ultrathin film.

PubMed

Li, Zhixiong; Liang, Ruizheng; Liu, Wendi; Yan, Dongpeng; Wei, Min

2015-10-28

Stimuli-responsive fluorescent switches have shown broad applications in optical devices, biological materials and intelligent responses. Herein, we describe the design and fabrication of a dual-stimuli-responsive fluorescent switch ultrathin film (UTF) via a three-step layer-by-layer (LBL) technique: (i) encapsulation of spiropyran (SP) within an amphiphilic block copolymer (PTBEM) to give the (SP@PTBEM) micelle; (ii) the mixture of riboflavin (Rf) and poly(styrene 4-sulfonate) (PSS) to enhance the adhesion ability of small molecules; (iii) assembly of negatively charged SP@PTBEM and Rf-PSS with cationic layered double hydroxide (LDH) nanoplatelets to obtain the (Rf-PSS/LDH/SP@PTBEM)n UTFs (n: bilayer number). The assembly process of the UTFs and their luminescence properties, as monitored by fluorescence spectroscopy and scanning electron microscopy (SEM), present a uniform and ordered layered structure with stepwise growth. The resulting Rf-PSS/LDH/SP@PTBEM UTF serves as a three-state switchable multicolor (green, yellow, and red) luminescent system based on stimulation from UV/Vis light and pH, with an acceptable reversibility. Therefore, this work provides a facile way to fabricate stimuli-responsive solid-state film switches with tunable-color luminescence, which have potential applications in the areas of displays, sensors, and rewritable optical memory and fluorescent logic devices.

Impedance matched, high-power, rf antenna for ion cyclotron resonance heating of a plasma

DOEpatents

Baity, Jr., Frederick W.; Hoffman, Daniel J.; Owens, Thomas L.

1988-01-01

A resonant double loop radio frequency (rf) antenna for radiating high-power rf energy into a magnetically confined plasma. An inductive element in the form of a large current strap, forming the radiating element, is connected between two variable capacitors to form a resonant circuit. A real input impedance results from tapping into the resonant circuit along the inductive element, generally near the midpoint thereof. The impedance can be matched to the source impedance by adjusting the separate capacitors for a given tap arrangement or by keeping the two capacitances fixed and adjustng the tap position. This results in a substantial reduction in the voltage and current in the transmission system to the antenna compared to unmatched antennas. Because the complete circuit loop consisting of the two capacitors and the inductive element is resonant, current flows in the same direction along the entire length of the radiating element and is approximately equal in each branch of the circuit. Unidirectional current flow permits excitation of low order poloidal modes which penetrate more deeply into the plasma.

[Investigation of sleep disorders in the vicinity of high frequency transmitters].

PubMed

Leitgeb, N; Schröttner, J; Cech, R; Kerbl, R

2004-08-01

To investigate the potential impact of RF electromagnetic fields of transmitters on the sleep quality of nearby residents, a new study design is presented. In a double-blind crossover field study the effect of on-site shielding, rather than of additional exposure, is investigated. For improved sleep quality differentiation the polysomnographic parameters are expanded by additional parameters. The feasibility study showed that checking the raw data and correcting the software-generated results by visual reading of the polysomnographic recordings is essential. Long-term RF measurement showed that exposure may vary considerably throughout the night, as well as from one night to the next. This variation may be greater than the GSM contribution itself. Mostly, the contributions of USW radio frequency fields dominated over GSM. Thus, continuous broadband RF recording is required for reliable interpretation of the results, in particular with regard to the potential role of mobile telephony emissions. Results show that simple sleep monitoring systems based on single-channel EEG analysis without acces to original biosignals are not adequate for sleep studies.

Device simulation of GeSn/GeSiSn pocket n-type tunnel field-effect transistor for analog and RF applications

NASA Astrophysics Data System (ADS)

Wang, Suyuan; Zheng, Jun; Xue, Chunlai; Li, Chuanbo; Zuo, Yuhua; Cheng, Buwen; Wang, Qiming

2017-11-01

We present the device simulations of analog and radio frequency (RF) performances of four double-gate pocket n-type tunneling field-effect transistors (NTFETs). The direct current (DC), analog and RF performances of the Ge-homo, GeSn-homo, GeSn/Ge and GeSn/GeSiSn NTFETs, are compared. The GeSn NTFETs greatly improve the on-state current (ION) and average subthreshold slope (SS), when compared with the Ge NTFET. Moreover, the GeSn/GeSiSn NTFET has the largest intrinsic gain (Av), and exhibits a suppressed ambipolar behavior, improved cut-off frequency (fT), and gain bandwidth product (GBW), according to the analyzed analog and RF figures of merit (FOM). Therefore, it can be concluded that the GeSn/GeSiSn NTFET has great potential as a promising candidate for the realization of future generation low-power analog/RF applications.

Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films

NASA Astrophysics Data System (ADS)

Gnapareddy, Bramaramba; Dugasani, Sreekantha Reddy; Son, Junyoung; Park, Sung Ha

2018-02-01

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF]C, approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF]C. [RF]C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF]C followed by an increase above [RF]C. By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices.

Topological, chemical and electro-optical characteristics of riboflavin-doped artificial and natural DNA thin films

PubMed Central

Gnapareddy, Bramaramba; Son, Junyoung

2018-01-01

DNA is considered as a useful building bio-material, and it serves as an efficient template to align functionalized nanomaterials. Riboflavin (RF)-doped synthetic double-crossover DNA (DX-DNA) lattices and natural salmon DNA (SDNA) thin films were constructed using substrate-assisted growth and drop-casting methods, respectively, and their topological, chemical and electro-optical characteristics were evaluated. The critical doping concentrations of RF ([RF]C, approx. 5 mM) at given concentrations of DX-DNA and SDNA were obtained by observing the phase transition (from crystalline to amorphous structures) of DX-DNA and precipitation of SDNA in solution above [RF]C. [RF]C are verified by analysing the atomic force microscopy images for DX-DNA and current, absorbance and photoluminescence (PL) for SDNA. We study the physical characteristics of RF-embedded SDNA thin films, using the Fourier transform infrared spectrum to understand the interaction between the RF and DNA molecules, current to evaluate the conductance, absorption to understand the RF binding to the DNA and PL to analyse the energy transfer between the RF and DNA. The current and UV absorption band of SDNA thin films decrease up to [RF]C followed by an increase above [RF]C. By contrast, the PL intensity illustrates the reverse trend, as compared to the current and UV absorption behaviour as a function of the varying [RF]. Owing to the intense PL characteristic of RF, the DNA lattices and thin films with RF might offer immense potential to develop efficient bio-sensors and useful bio-photonic devices. PMID:29515837

Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain.

PubMed

Alecci, M; Romanzetti, S; Kaffanke, J; Celik, A; Wegener, H P; Shah, N J

2006-08-01

MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides (1)H and (23)Na images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the (1)H frequency and a smaller co-planar loop tuned to the (23)Na frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned (23)Na coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the (23)Na sensitivity (about 28 %) because of signal losses in the trap inductance. Typical congruent (1)H and (23)Na rat brain images showing good SNR ((23)Na: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution ((23)Na: 1.25 x 1.25 x 5mm(3)) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature.

Toward Realization of 2.4 GHz Balunless Narrowband Receiver Front-End for Short Range Wireless Applications.

PubMed

El-Desouki, Munir M; Qasim, Syed Manzoor; BenSaleh, Mohammed S; Deen, M Jamal

2015-05-07

The demand for radio frequency (RF) transceivers operating at 2.4 GHz band has attracted considerable research interest due to the advancement in short range wireless technologies. The performance of RF transceivers depends heavily on the transmitter and receiver front-ends. The receiver front-end is comprised of a low-noise amplifier (LNA) and a downconversion mixer. There are very few designs that focus on connecting the single-ended output LNA to a double-balanced mixer without the use of on-chip transformer, also known as a balun. The objective of designing such a receiver front-end is to achieve high integration and low power consumption. To meet these requirements, we present the design of fully-integrated 2.4 GHz receiver front-end, consisting of a narrow-band LNA and a double balanced mixer without using a balun. Here, the single-ended RF output signal of the LNA is translated into differential signal using an NMOS-PMOS (n-channel metal-oxide-semiconductor, p-channel metal-oxide-semiconductor) transistor differential pair instead of the conventional NMOS-NMOS transistor configuration, for the RF amplification stage of the double-balanced mixer. The proposed receiver circuit fabricated using TSMC 0.18 µm CMOS technology operates at 2.4 GHz and produces an output signal at 300 MHz. The fabricated receiver achieves a gain of 16.3 dB and consumes only 6.74 mW operating at 1.5 V, while utilizing 2.08 mm2 of chip area. Measurement results demonstrate the effectiveness and suitability of the proposed receiver for short-range wireless applications, such as in wireless sensor network (WSN).

Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain

NASA Astrophysics Data System (ADS)

Alecci, M.; Romanzetti, S.; Kaffanke, J.; Celik, A.; Wegener, H. P.; Shah, N. J.

2006-08-01

MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides 1H and 23Na images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the 1H frequency and a smaller co-planar loop tuned to the 23Na frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned 23Na coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the 23Na sensitivity (about 28 %) because of signal losses in the trap inductance. Typical congruent 1H and 23Na rat brain images showing good SNR ( 23Na: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution ( 23Na: 1.25 × 1.25 × 5 mm 3) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature.

Role of Escherichia coli dnaG function in coliphage M13 DNA synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dasgupta, S.; Mitra, S.

Examination of the role of Escherichia coli dnaG function in different stages of M13 phage DNA synthesis by ultracentrifugal analysis of intracellular phage DNA in a thermosensitive dnaG mutant shows that: (a) the formation of parental double-strand replicative-form DNA (rfDNA) from the infecting virus is independent of dnaG function; (b) the synthesis of progeny rfDNA requires dnaG product; (c) after a pool of rfDNA is made up, dnaG function is not required for the progeny single-strand DNA (ssDNA) synthesis. The ssDNAs produced under nonpermissive condition are mostly circular and biologically functional.

Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

NASA Astrophysics Data System (ADS)

Baudrenghien, P.; Mastoridis, T.

2015-10-01

The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of β* to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

Measured performance of the GTA rf systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denney, P.M.; Jachim, S.P.

1993-06-01

This paper describes the performance of the RF systems on the Ground Test Accelerator (GTA). The RF system architecture is briefly described. Among the RF performance results presented are RF field flatness and stability, amplitude and phase control resolution, and control system bandwidth and stability. The rejection by the RF systems of beam-induced disturbances, such as transients and noise, are analyzed. The observed responses are also compared to computer-based simulations of the RF systems for validation.

Measured performance of the GTA rf systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Denney, P.M.; Jachim, S.P.

1993-01-01

This paper describes the performance of the RF systems on the Ground Test Accelerator (GTA). The RF system architecture is briefly described. Among the RF performance results presented are RF field flatness and stability, amplitude and phase control resolution, and control system bandwidth and stability. The rejection by the RF systems of beam-induced disturbances, such as transients and noise, are analyzed. The observed responses are also compared to computer-based simulations of the RF systems for validation.

Effects of mobile phone exposure (GSM 900 and WCDMA/UMTS) on polysomnography based sleep quality: An intra- and inter-individual perspective.

PubMed

Danker-Hopfe, Heidi; Dorn, Hans; Bolz, Thomas; Peter, Anita; Hansen, Marie-Luise; Eggert, Torsten; Sauter, Cornelia

2016-02-01

Studies on effects of radio frequency-electromagnetic fields (RF-EMF) on the macrostructure of sleep so far yielded inconsistent results. This study investigated whether possible effects of RF-EMF exposure differ between individuals. In a double-blind, randomized, sham-controlled cross-over study possible effects of electromagnetic fields emitted by pulsed Global System for Mobile Communications (GSM) 900 and Wideband Code-Division Multiple Access (WCDMA)/Universal Mobile Telecommunications System (WCDMA/UMTS) devices on sleep were analysed. Thirty healthy young men (range 18-30 years) were exposed three times per exposure condition while their sleep was recorded. Sleep was evaluated according to the American Academy of Sleep Medicine standard and eight basic sleep variables were considered. Data analyses at the individual level indicate that RF-EMF effects are observed in 90% of the individuals and that all sleep variables are affected in at least four subjects. While sleep of participants was affected in various numbers, combinations of sleep variables and in different directions, showing improvements but also deteriorations, the only consistent finding was an increase of stage R sleep under GSM 900MHz exposure (9 of 30 subjects) as well as under WCDMA/UMTS exposure (10 of 30 subjects). The results underline that sleep of individuals can be affected differently. The observations found here may indicate an underlying thermal mechanism of RF-EMF on human REM sleep. Nevertheless, the effect of an increase in stage R sleep in one third of the individuals does not necessarily indicate a disturbance of sleep. Copyright © 2015 Elsevier Inc. All rights reserved.

Rf Feedback free electron laser

DOEpatents

Brau, Charles A.; Swenson, Donald A.; Boyd, Jr., Thomas J.

1981-01-01

A free electron laser system and electron beam system for a free electron laser which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

An investigation of the DC and RF performance of InP DHBTs transferred to RF CMOS wafer substrate

NASA Astrophysics Data System (ADS)

Ren, Kun; Zheng, Jiachen; Lu, Haiyan; Liu, Jun; Wu, Lishu; Zhou, Wenyong; Cheng, Wei

2018-05-01

This paper investigated the DC and RF performance of the InP double heterojunction bipolar transistors (DHBTs) transferred to RF CMOS wafer substrate. The measurement results show that the maximum values of the DC current gain of a substrate transferred device had one emitter finger, of 0.8 μm in width and 5 μm in length, are changed unobviously, while the cut-off frequency and the maximum oscillation frequency are decreased from 220 to 171 GHz and from 204 to 154 GHz, respectively. In order to have a detailed insight on the degradation of the RF performance, small-signal models for the InP DHBT before and after substrate transferred are presented and comparably extracted. The extracted results show that the degradation of the RF performance of the device transferred to RF CMOS wafer substrate are mainly caused by the additional introduced substrate parasitics and the increase of the capacitive parasitics induced by the substrate transfer process itself. Project supported by the National Natural Science Foundation of China (No. 61331006) and the Natural Science Foundation of Zhejiang Province (No. Y14F010017).

Rf feedback free electron laser

DOEpatents

Brau, C.A.; Swenson, D.A.; Boyd, T.J. Jr.

1979-11-02

A free electron laser system and electron beam system for a free electron laser are provided which use rf feedback to enhance efficiency. Rf energy is extracted from an electron beam by decelerating cavities and returned to accelerating cavities using rf returns such as rf waveguides, rf feedthroughs, etc. This rf energy is added to rf klystron energy to lower the required input energy and thereby enhance energy efficiency of the system.

A two-dimensional (2D) analytical subthreshold swing and transconductance model of underlap dual-material double-gate (DMDG) MOSFET for analog/RF applications

NASA Astrophysics Data System (ADS)

Narendar, Vadthiya; Rai, Saurabh; Tiwari, Siddharth; Mishra, R. A.

2016-12-01

The double-gate (DG) metal-oxide-semiconductor field effect transistors (MOSFETs) are the choice of technology in sub -100 nm regime of leading microelectronics industry. To enhance the analog and RF performance of DG MOSFET, an underlap dual-material (DM) DG MOSFET device structure has been considered because, it has the advantages of both underlap as well as that of dual-material gate (DMG). A 2D analytical surface potential, subthreshold current, subthreshold swing as well as transconductance modelling of underlap DMDG MOSFET has been done by solving the Poisson's equation. It has also been found that, numerically simulated data approves the analytically modelled data with commendable accuracy. As underlap length (Lun) increases, a substantial reduction of subthreshold current due to enhanced gate control over channel regime is observed. DMG structure facilitates to improve the average velocity of carriers which leads to superior drive current of the device. The underlap DMDG MOSFET device structure demonstrates an ameliorated subthreshold characteristic. The analog figure of merits (FOMs) such as transconductance (gm), transconductance generation factor (TGF), output conductance (gd), early voltage (VEA), intrinsic gain (AV) and RF FOMs namely cut-off frequency (fT), gain frequency product (GFP), transconductance frequency product (TFP) and gain transconductance frequency product (GTFP) have been evaluated. The aforesaid analysis revels that, the device is best suited for communication related Analog/RF applications.

Frequency-doubled microwave waveforms generation using a dual-polarization quadrature phase shift keying modulator driven by a single frequency radio frequency signal

NASA Astrophysics Data System (ADS)

Zhu, Zihang; Zhao, Shanghong; Li, Xuan; Qu, Kun; Lin, Tao

2018-01-01

A photonic approach to generate frequency-doubled microwave waveforms using an integrated dual-polarization quadrature phase shift keying (DP-QPSK) modulator driven by a sinusoidal radio frequency (RF) signal is proposed. By adjusting the dc bias points of the DP-QPSK modulator, the obtained second-order and six-order harmonics are in phase while the fourth-order harmonics are complementary when the orthogonal polarized outputs of the modulator are photodetected. After properly setting the modulation indices of the modulator, the amplitude of the second-order harmonic is 9 times of that of the six-order harmonic, indicating a frequency-doubled triangular waveform is generated. If a broadband 90° microwave phase shifter is attached after the photodetector (PD) to introduce a 90° phase shift, a frequency-doubled square waveform can be obtained after adjusting the amplitude of the second-order harmonic 3 times of that of the six-order harmonic. The proposal is first theoretically analyzed and then validated by simulation. Simulation results show that a 10 GHz triangular and square waveform sequences are successfully generated from a 5 GHz sinusoidal RF drive signal.

High stability buffered phase comparator

NASA Technical Reports Server (NTRS)

Adams, W. A.; Reinhardt, V. S. (Inventor)

1984-01-01

A low noise RF signal phase comparator comprised of two high stability driver buffer amplifiers driving a double balanced mixer which operate to generate a beat frequency between the two RF input signals coupled to the amplifiers from the RF sources is described. The beat frequency output from the mixer is applied to a low noise zero crossing detector which is the phase difference between the two RF inputs. Temperature stability is provided by mounting the amplifiers and mixer on a common circuit board with the active circuit elements located on one side of a circuit board and the passive circuit elements located on the opposite side. A common heat sink is located adjacent the circuit board. The active circuit elements are embedded into the bores of the heat sink which slows the effect of ambient temperature changes and reduces the temperature gradients between the active circuit elements, thus improving the cancellation of temperature effects. The two amplifiers include individual voltage regulators, which increases RF isolation.

DOUBLE ENDOR with a linearly and a circularly polarized radiofrequency field

NASA Astrophysics Data System (ADS)

Schweiger, A.; Rudin, M.; Forrer, J.; Günthard, Hs. H.

The combination of the two spectroscopical techniques, DOUBLE ENDOR and ENDOR with a circularly polarized radiofrequency field (CP-ENDOR), is described. with this new method, termed by the acronym CP-DOUBLE ENDOR, the selective induction of transitions of different types of nuclei and of different paramagnetic species allows a drastic reduction of the number of observed ENDOR lines. With this technique, analysis of hitherto not interpretable ENDOR spectra is often made possible. The experimental setup of the CP-DOUBLE ENDOR spectrometer is described. The advantage of using circularly polarized rf fields in DOUBLE ENDOR spectroscopy is illustrated by two applications on transition metal complexes in single crystals.

Single electron beam rf feedback free electron laser

DOEpatents

Brau, C.A.; Stein, W.E.; Rockwood, S.D.

1981-02-11

A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

Recent developments in trapping and manipulation of atoms with adiabatic potentials

NASA Astrophysics Data System (ADS)

Garraway, Barry M.; Perrin, Hélène

2016-09-01

A combination of static and oscillating magnetic fields can be used to ‘dress’ atoms with radio-frequency (RF), or microwave, radiation. The spatial variation of these fields can be used to create an enormous variety of traps for ultra-cold atoms and quantum gases. This article reviews the type and character of these adiabatic traps and the applications which include atom interferometry and the study of low-dimensional quantum systems. We introduce the main concepts of magnetic traps leading to adiabatic dressed traps. The concept of adiabaticity is discussed in the context of the Landau-Zener model. The first bubble trap experiment is reviewed together with the method used for loading it. Experiments based on atom chips show the production of double wells and ring traps. Dressed atom traps can be evaporatively cooled with an additional RF field, and a weak RF field can be used to probe the spectroscopy of the adiabatic potentials. Several approaches to ring traps formed from adiabatic potentials are discussed, including those based on atom chips, time-averaged adiabatic potentials and induction methods. Several proposals for adiabatic lattices with dressed atoms are also reviewed.

Electromagnetic Modeling of Distributed-Source-Excitation of Coplanar Waveguides: Applications to Traveling-Wave Photomixers

NASA Technical Reports Server (NTRS)

Pasqualini, Davide; Neto, Andrea; Wyss, Rolf A.

2001-01-01

In this work an electromagnetic model and subsequent design is presented for a traveling-wave, coplanar waveguide (CPW) based source that will operate in the THz frequency regime. The radio frequency (RF) driving current is a result of photoexcitation of a thin GaAs membrane using two frequency-offset lasers. The GaAs film is grown by molecular-beam-epitaxy (MBE) and displays sub-ps carrier lifetimes which enable the material conductivity to be modulated at a very high rate. The RF current flows between electrodes deposited on the GaAs membrane which are biased with a DC voltage source. The electrodes form a CPW and are terminated with a double slot antenna that couples the power to a quasi-optical system. The membrane is suspended above a metallic reflector to launch all radiation in one direction. The theoretical investigation and consequent design is performed in two steps. The first step consists of a direct evaluation of the magnetic current distribution on an infinitely extended coplanar waveguide excited by an impressed electric current distributed over a finite area. The result of the analysis is the difference between the incident angle of the laser beams and the length of the excited area that maximizes the RF power coupled to the CPW. The optimal values for both parameters are found as functions of the CPW and membrane dimensions as well as the dielectric constants of the layers. In the second step, a design is presented of a double slot antenna that matches the CPW characteristic impedance and gives good overall performance. The design is presently being implemented and measurements will soon be available.

Lattice design for the CEPC double ring scheme

NASA Astrophysics Data System (ADS)

Wang, Yiwei; Su, Feng; Bai, Sha; Zhang, Yuan; Bian, Tianjian; Wang, Dou; Yu, Chenghui; Gao, Jie

2018-01-01

A future Circular Electron Positron Collider (CEPC) has been proposed by China with the main goal of studying the Higgs boson. Its baseline design, chosen on the basis of its performance, is a double ring scheme; an alternative design is a partial double ring scheme which reduces the budget while maintaining an adequate performance. This paper will present the collider ring lattice design for the double ring scheme. The CEPC will also work as a W and a Z factory. For the W and Z modes, except in the RF region, compatible lattices were obtained by scaling down the magnet strength with energy.

A Phase 1 Randomized, Blinded Comparison of the Pharmacokinetics and Colonic Distribution of Three Candidate Rectal Microbicide Formulations of Tenofovir 1% Gel with Simulated Unprotected Sex (CHARM-02)

PubMed Central

Hiruy, Hiwot; Fuchs, Edward J.; Marzinke, Mark A.; Bakshi, Rahul P.; Breakey, Jennifer C.; Aung, Wutyi S.; Manohar, Madhuri; Yue, Chen; Caffo, Brian S.; Du, Yong; Abebe, Kaleab Z.; Spiegel, Hans M.L.; Rohan, Lisa C.; McGowan, Ian

2015-01-01

Abstract CHARM-02 is a crossover, double-blind, randomized trial to compare the safety and pharmacokinetics of three rectally applied tenofovir 1% gel candidate rectal microbicides of varying osmolalities: vaginal formulation (VF) (3111 mOsmol/kg), the reduced glycerin vaginal formulation (RGVF) (836 mOsmol/kg), and an isoosmolal rectal-specific formulation (RF) (479 mOsmol/kg). Participants (n = 9) received a single, 4 ml, radiolabeled dose of each gel twice, once with and once without simulated unprotected receptive anal intercourse (RAI). The safety, plasma tenofovir pharmacokinetics, colonic small molecule permeability, and SPECT/CT imaging of lower gastrointestinal distribution of drug and virus surrogate were assessed. There were no Grade 3 or 4 adverse events reported for any of the products. Overall, there were more Grade 2 adverse events in the VF group compared to RF (p = 0.006) and RGVF (p = 0.048). In the absence of simulated unprotected RAI, VF had up to 3.8-fold greater systemic tenofovir exposure, 26- to 234-fold higher colonic permeability of the drug surrogate, and 1.5- to 2-fold greater proximal migration in the colonic lumen, when compared to RF and RGVF. Similar trends were observed with simulated unprotected RAI, but most did not reach statistical significance. SPECT analysis showed 86% (standard deviation 19%) of the drug surrogate colocalized with the virus surrogate in the colonic lumen. There were no significant differences between the RGVF and RF formulation, with the exception of a higher plasma tenofovir concentration of RGVF in the absence of simulated unprotected RAI. VF had the most adverse events, highest plasma tenofovir concentrations, greater mucosal permeability of the drug surrogate, and most proximal colonic luminal migration compared to RF and RGVF formulations. There were no major differences between RF and RGVF formulations. Simultaneous assessment of toxicity, systemic and luminal pharmacokinetics, and colocalization of drug and viral surrogates substantially informs rectal microbicide product development. PMID:26227279

Prospective evaluation of a simplified approach for common atrial flutter radio frequency ablation with only two catheters.

PubMed

Klug, D; Lacroix, D; Marquié, C; Mairesse, G; Alix, D; Dennetière, S; d'Hautefeuille, B; Zghal, N; Kacet, S

2001-07-01

Intra-atrial conduction block within the inferior vena cava-tricuspid annulus isthmus (IVCT) has been shown to predict successful common atrial flutter ablation. However, its demonstration requires the use of several electrode catheters and mapping of the line of block. The aim of this study was prospectively to test the feasibility of a simplified ablation procedure using only two catheters. Radio frequency (RF) ablation of common atrial flutter was performed in 30 patients with the sole use of a catheter for atrial pacing and a RF catheter. RF ablation lesions were created in the IVCT. Surface ECG criteria were used to monitor the conduction within the IVCT. The end point during low lateral atrial pacing was an increment in the interval between the pacing artefact and the peak of the R wave in surface lead II >50 ms and clockwise rotation of the P wave axis beyond -30 degrees and inferiorly. Then, the line of lesions was mapped during atrial pacing with the RF catheter. Additional RF lesions were applied if mapping disclosed a zone of residual conduction. Otherwise the procedure was stopped if mapping showed parallel double potentials all along the line. Finally, the block was reassessed with a 'Halo' catheter. Surface ECG criteria were met in 26 patients. Mapping the line of lesions showed a complete corridor of parallel double potentials in these 26 cases and in 3 of the 4 patients in whom ECG criteria were not met. Conduction evaluated with the Halo catheter showed bi-directional complete block in these 29 patients. After a follow-up of 16 +/- 4 months there was no recurrence of atrial flutter. Surface ECG criteria combined with mapping of the line of block demonstrate evidence of bi-directional IVCT block. This simplified RF ablation of common atrial flutter is feasible with a low recurrence rate.

Investigation of radiofrequency plasma sources for space travel

NASA Astrophysics Data System (ADS)

Charles, C.; Boswell, R. W.; Takahashi, K.

2012-12-01

Optimization of radiofrequency (RF) plasma sources for the development of space thrusters differs from other applications such as plasma processing of materials since power efficiency, propellant usage, particle acceleration or heating become driving parameters. The development of two RF (13.56 MHz) plasma sources, the high-pressure (˜1 Torr) capacitively coupled ‘pocket rocket’ plasma micro-thruster and the low-pressure (˜1 mTorr) inductively coupled helicon double layer thruster (HDLT), is discussed within the context of mature and emerging electric propulsion devices. The density gradient in low-pressure expanding RF plasmas creates an electric field that accelerates positive ions out of the plasma. Generally, the total potential drop is similar to that of a wall sheath allowing the plasma electrons to neutralize the ion beam. A high-pressure expansion with no applied magnetic field can result in large dissociation rates and/or a collimated beam of ions of small area and a flowing heated neutral beam (‘pocket rocket’). A low-pressure expansion dominated by a magnetic field can result in the formation of electric double layers which produce a very directed neutralized beam of ions of large area (HDLT).

Novel exposure units for at-home personalized testing of electromagnetic sensibility.

PubMed

Huss, Anke; Murbach, Manuel; van Moorselaar, Imke; Kuster, Niels; van Strien, Rob; Kromhout, Hans; Vermeulen, Roel; Slottje, Pauline

2016-01-01

Previous experimental studies on electromagnetic hypersensitivity have been criticized regarding inflexibility of choice of exposure and of study locations. We developed and tested novel portable exposure units that can generate different output levels of various extremely low frequency magnetic fields (ELF-MF; 50 Hz field plus harmonics) and radiofrequency electromagnetic fields (RF-EMF). Testing was done with a group of healthy volunteers (n = 25 for 5 ELF-MF and n = 25 for 5 RF-EMF signals) to assess if units were indeed able to produce double-blind exposure conditions. Results substantiated that double-blind conditions were met; on average participants scored 50.6% of conditions correct on the ELF-MF, and 50.0% on the RF-EMF unit, which corresponds to guessing probability. No cues as to exposure conditions were reported. We aim to use these units in a future experiment with subjects who wish to test their personal hypothesis of being able to sense or experience when being exposed to EMF. The new units allow for a high degree of flexibility regarding choice of applied electromagnetic signal, output power level and location (at home or another environment of subjects' choosing). © 2015 Wiley Periodicals, Inc.

Radio frequency switching network: a technique for infrared sensing

NASA Astrophysics Data System (ADS)

Mechtel, Deborah M.; Jenkins, R. Brian; Joyce, Peter J.; Nelson, Charles L.

2016-10-01

This paper describes a unique technique that implements photoconductive sensors in a radio frequency (RF) switching network designed to locate in real-time the position and intensity of IR radiation incident on a composite structure. In the implementation described here, photoconductive sensors act as rapid response switches in a two-layer RF network embedded in an FR-4 laminate. To detect radiation, phosphorous-doped silicon photoconductive sensors are inserted in GHz range RF transmission lines. By permitting signal propagation only when a sensor is illuminated, the RF signals are selectively routed from lower layer transmission lines to upper layer lines, thereby pinpointing the location and strength of incident radiation. Simulations based on a high frequency three-dimensional planar electromagnetics model are presented and compared to the experimental results. The experimental results are described for GHz range RF signal control for 300- and 180-mW incident energy from 975- to 1060-nm wavelength lasers, respectively, where upon illumination, RF transmission line signal output power doubled when compared to nonilluminated results. The experimental results are also reported for 100-W incident energy from a 1060-nm laser. Test results illustrate real-time signal processing would permit a structure to be controlled in response to incident radiation.

Molecular determinants for the high constitutive activity of the human histamine H4 receptor: functional studies on orthologues and mutants

PubMed Central

Wifling, D; Löffel, K; Nordemann, U; Strasser, A; Bernhardt, G; Dove, S; Seifert, R; Buschauer, A

2015-01-01

Background and Purpose Some histamine H4 receptor ligands act as inverse agonists at the human H4 receptor (hH4R), a receptor with exceptionally high constitutive activity, but as neutral antagonists or partial agonists at the constitutively inactive mouse H4 receptor (mH4R) and rat H4 receptor (rH4R). To study molecular determinants of constitutive activity, H4 receptor reciprocal mutants were constructed: single mutants: hH4R-F169V, mH4R-V171F, hH4R-S179A, hH4R-S179M; double mutants: hH4R-F169V+S179A, hH4R-F169V+S179M and mH4R-V171F+M181S. Experimental Approach Site-directed mutagenesis with pVL1392 plasmids containing hH4 or mH4 receptors were performed. Wild-type or mutant receptors were co-expressed with Gαi2 and Gβ1γ2 in Sf9 cells. Membranes were studied in saturation and competition binding assays ([3H]-histamine), and in functional [35S]-GTPγS assays with inverse, partial and full agonists of the hH4 receptor. Key Results Constitutive activity decreased from the hH4 receptor via the hH4R-F169V mutant to the hH4R-F169V+S179A and hH4R-F169V+S179M double mutants. F169 alone or in concert with S179 plays a major role in stabilizing a ligand-free active state of the hH4 receptor. Partial inverse hH4 receptor agonists like JNJ7777120 behaved as neutral antagonists or partial agonists at species orthologues with lower or no constitutive activity. Some partial and full hH4 receptor agonists showed decreased maximal effects and potencies at hH4R-F169V and double mutants. However, the mutation of S179 in the hH4 receptor to M as in mH4 receptor or A as in rH4 receptor did not significantly reduce constitutive activity. Conclusions and Implications F169 and S179 are key amino acids for the high constitutive activity of hH4 receptors and may also be of relevance for other constitutively active GPCRs. Linked Articles This article is part of a themed issue on Histamine Pharmacology Update published in volume 170 issue 1. To view the other articles in this issue visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2013.170.issue-1/issuetoc PMID:24903527

Investigation and statistical modeling of InAs-based double gate tunnel FETs for RF performance enhancement

NASA Astrophysics Data System (ADS)

Poorvasha, S.; Lakshmi, B.

2018-05-01

In this paper, RF performance analysis of InAs-based double gate (DG) tunnel field effect transistors (TFETs) is investigated in both qualitative and quantitative fashion. This investigation is carried out by varying the geometrical and doping parameters of TFETs to extract various RF parameters, unity gain cut-off frequency (f t), maximum oscillation frequency (f max), intrinsic gain and admittance (Y) parameters. An asymmetric gate oxide is introduced in the gate-drain overlap and compared with that of DG TFETs. Higher ON-current (I ON) of about 0.2 mA and less leakage current (I OFF) of 29 fA is achieved for DG TFET with gate-drain overlap. Due to increase in transconductance (g m), higher f t and intrinsic gain is attained for DG TFET with gate-drain overlap. Higher f max of 985 GHz is obtained for drain doping of 5 × 1017 cm‑3 because of the reduced gate-drain capacitance (C gd) with DG TFET with gate-drain overlap. In terms of Y-parameters, gate oxide thickness variation offers better performance due to the reduced values of C gd. A second order numerical polynomial model is generated for all the RF responses as a function of geometrical and doping parameters. The simulation results are compared with this numerical model where the predicted values match with the simulated values. Project supported by the Department of Science and Technology, Government of India under SERB Scheme (No. SERB/F/2660).

Efficient, balanced, transmission line RF circuits by back propagation of common impedance nodes.

PubMed

Markhasin, Evgeny; Hu, Jianping; Su, Yongchao; Herzfeld, Judith; Griffin, Robert G

2013-06-01

We present a new, efficient strategy for designing fully balanced transmission line RF circuits for solid state NMR probes based on back propagation of common impedance nodes (BPCIN). In this approach, the impedance node phenomenon is the sole means of achieving mutual RF isolation and balance in all RF channels. BPCIN is illustrated using a custom double resonance 3.2 mm MAS probe operating at 500 MHz ((1)H) and 125 MHz ((13)C). When fully optimized, the probe is capable of producing high homogeneity (810°/90° ratios of 86% and 89% for (1)H and (13)C, respectively) and high efficiency (γB1=100 kHz for (1)H and (13)C at 70 W and 180 W of RF input, respectively; up to 360 kHz for (1)H). The probe's performance is illustrated by 2D MAS correlation spectra of microcrystals of the tripeptide N-f-MLF-OH and hydrated amyloid fibrils of the protein PI3-SH3. Copyright © 2013 Elsevier Inc. All rights reserved.

Simultaneous radiofrequency (RF) heating and magnetic resonance (MR) thermal mapping using an intravascular MR imaging/RF heating system.

PubMed

Qiu, Bensheng; El-Sharkawy, Abdel-Monem; Paliwal, Vaishali; Karmarkar, Parag; Gao, Fabao; Atalar, Ergin; Yang, Xiaoming

2005-07-01

Previous studies have confirmed the possibility of using an intravascular MR imaging guidewire (MRIG) as a heating source to enhance vascular gene transfection/expression. This motivated us to develop a new intravascular system that can perform MR imaging, radiofrequncy (RF) heating, and MR temperature monitoring simultaneously in an MR scanner. To validate this concept, a series of mathematical simulations of RF power loss along a 0.032-inch MRIG and RF energy spatial distribution were performed to determine the optimum RF heating frequency. Then, an RF generator/amplifier and a filter box were built. The possibility for simultaneous RF heating and MR thermal mapping of the system was confirmed in vitro using a phantom, and the obtained thermal mapping profile was compared with the simulated RF power distribution. Subsequently, the feasibility of simultaneous RF heating and temperature monitoring was successfully validated in vivo in the aorta of living rabbits. This MR imaging/RF heating system offers a potential tool for intravascular MR-mediated, RF-enhanced vascular gene therapy.

Airborne RF Measurement System (ARMS) and Analysis of Representative Flight RF Environment

NASA Technical Reports Server (NTRS)

Koppen, Sandra V.; Ely, Jay J.; Smith, Laura J.; Jones, Richard A.; Fleck, Vincent J.; Salud, Maria Theresa; Mielnik, John J.

2007-01-01

Environmental radio frequency (RF) data over a broad band of frequencies (30 MHz to 1000 MHz) were obtained to evaluate the electromagnetic environment in airspace around several airports. An RF signal measurement system was designed utilizing a spectrum analyzer connected to the NASA Lancair Columbia 300 aircraft's VHF/UHF navigation antenna. This paper presents an overview of the RF measurement system and provides analysis of sample RF signal measurement data. This aircraft installation package and measurement system can be quickly returned to service if needed by future projects requiring measurement of an RF signal environment or exploration of suspected interference situations.

Radio Frequency (RF) Micro-Electromechanical Systems (MEMS) Switches for Space Communications

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Ponchak, George E.; Scardelletti, Maximillian C.; Varaljay, Nicholas C.

2000-01-01

Micro-electromechanical systems (MEMS) is an emerging technology for radio frequency (RF) systems because it has the potential to dramatically decrease loss and improve efficiency. In this paper, we address the design and fabrication of novel MEMS switches being developed at NASA Glenn Research Center. Two types of switches are being developed: a microstrip series single pole single throw (SPST) switch and a coplanar waveguide (CPW) series SPST and single pole double throw (SPDT) switches. These are being fabricated as an integral part of 50 Ohm microstrip and CPW RF integrated circuits using microfabrication techniques. The construction of the switch relies on a cantilever beam that is partially supported by a dielectric post. The cantilever beam is electro-magnetically actuated. To decrease stiction, a Si3N4 thin film is deposited over the contact area. Thus, when the switch is closed, the ON-state insertion loss is governed by the parallel plate capacitance formed by the two contacts. The isolation in the OFF-state is governed by the parasitic capacitance when the cantilever is in the up position. RF MEMS switches have been demonstrated with 80% lower insertion loss than conventional solid state devices (GaAs Metal Semiconductor Field Effect Transistors (MESFETs) and Silicon PIN diodes) based switches. For example, a conventional GaAs five-bit phase shifter which is required for beam steering in a phased array antenna has approximately 7 dB of insertion loss at 26.5 GHz where as a comparable MEMS based phase shifter is expected to have only 2 dB of insertion loss. This translates into 56% lower power dissipation and therefore decreases the thermal load on the spacecraft and also reduces the power amplifier requirements. These benefits will enable NASA to build the next generation of deep space science crafts and micro/nano satellites.

ACCELERATORS: RF system design and measurement of HIRF-CSRe

NASA Astrophysics Data System (ADS)

Xu, Zhe; Zhao, Hong-Wei; Wang, Chun-Xiao; Xia, Jia-Wen; Zhan, Wen-Long; Bian, Zhi-Bin

2009-05-01

An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections: ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB interface and has three feedback loops. Finally we give the results of the measurement on our system.

Design and Vertical Tests of SPS-series Double-Quarter Wave (DQW) Cavity Prototypes for the HL-LHC Crab Cavity System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verdú-Andrés, S.; et al.

Crab crossing is essential for high-luminosity colliders. The High Luminosity Large Hadron Collider (HL-LHC) will equip one of its Interaction Points (IP1) with Double-Quarter Wave (DQW) crab cavities. A DQW cavity is a new generation of deflecting RF cavities that stands out for its compactness and broad frequency separation between fundamental and first high-order modes. The deflecting kick is provided by its fundamental mode. Each HL-LHC DQW cavity shall provide a nominal deflecting voltage of 3.4 MV, although up to 5.0 MV may be required. A Proof-of-Principle (PoP) DQW cavity was limited by quench at 4.6 MV. This paper describesmore » a new, highly optimized cavity, designated DQW SPS-series, which satisfies dimensional, cryogenic, manufacturing and impedance requirements for beam tests at SPS and operation in LHC. Two prototypes of this DQW SPS-series were fabricated by US industry and cold tested after following conventional SRF surface treatment. Both units outperformed the PoP cavity, reaching a deflecting voltage of 5.3-5.9 MV. This voltage - the highest reached by a DQW cavity - is well beyond the nominal voltage of 3.4 MV and may even operate at the ultimate voltage of 5.0MVwith sufficient margin. This paper covers fabrication, surface preparation and cryogenic RF test results and implications.« less

Airborne RF Measurement System and Analysis of Representative Flight RF Environment

NASA Technical Reports Server (NTRS)

Koppen, Sandra V.; Ely, Jay J.; Smith, Laura J.; Jones, Richard A.; Fleck, Vincent J.; Salud, Maria Theresa; Mielnik, John

2007-01-01

Environmental radio frequency (RF) data over a broad band of frequencies were needed to evaluate the airspace around several airports. An RF signal measurement system was designed using a spectrum analyzer connected to an aircraft VHF/UHF navigation antenna installed on a small aircraft. This paper presents an overview of the RF measurement system and provides analysis of a sample of RF signal measurement data over a frequency range of 30 MHz to 1000 MHz.

Components of treatment delay in rheumatoid arthritis differ according to autoantibody status: validation of a single-centre observation using national audit data.

PubMed

Pratt, Arthur G; Lendrem, Dennis; Hargreaves, Ben; Aslam, Osman; Galloway, James B; Isaacs, John D

2016-10-01

To determine whether time to treatment following symptom onset differs between RA patients according to autoantibody status. A single-centre retrospective analysis of a UK early RA inception cohort was first undertaken to identify those components of the patient journey that differed by serological subtype. Data from a UK national audit of early inflammatory arthritis patients was accessed to replicate the key finding. A total of 173 RA patients were diagnosed over a 31-month period, of whom 80 (46%) were ACPA/RF double-seropositive (ACPA(+)/RF(+)), 53 (31%) ACPA(-)/RF(-), 17 (10%) ACPA(+)/RF(-) and 23 (13%) RF(+)/ACPA(-) Overall, ACPA(+)/RF(+) patients experienced significantly longer symptom duration before DMARD initiation. This was accounted for by delays in their presentation to primary care following symptom onset-a finding that was robustly confirmed in an independent dataset of 2192 UK early RA patients. In contrast, ACPA(-)/RF(-) patients were significantly more likely to experience delays in DMARD initiation after presenting to secondary care. Causes of treatment delays in early RA differ according to patients' autoantibody status. More insidious symptom onset and/or distinct health-seeking behaviours among ACPA(+)/RF(+) patients may contribute to late presentations in primary care, whereas ACPA(-)/RF(-) patients experience delayed diagnosis and treatment in secondary care. These observations inform the research agenda, potentially influencing the design of service delivery for early arthritis patients. © The Author 2016. Published by Oxford University Press on behalf of the British Society for Rheumatology.

Solving the Orientation Specific Constraints in Transcranial Magnetic Stimulation by Rotating Fields

PubMed Central

Neef, Nicole E.; Agudelo-Toro, Andres; Rakhmilevitch, David; Paulus, Walter; Moses, Elisha

2014-01-01

Transcranial Magnetic Stimulation (TMS) is a promising technology for both neurology and psychiatry. Positive treatment outcome has been reported, for instance in double blind, multi-center studies on depression. Nonetheless, the application of TMS towards studying and treating brain disorders is still limited by inter-subject variability and lack of model systems accessible to TMS. The latter are required to obtain a deeper understanding of the biophysical foundations of TMS so that the stimulus protocol can be optimized for maximal brain response, while inter-subject variability hinders precise and reliable delivery of stimuli across subjects. Recent studies showed that both of these limitations are in part due to the angular sensitivity of TMS. Thus, a technique that would eradicate the need for precise angular orientation of the coil would improve both the inter-subject reliability of TMS and its effectiveness in model systems. We show here how rotation of the stimulating field relieves the angular sensitivity of TMS and provides improvements in both issues. Field rotation is attained by superposing the fields of two coils positioned orthogonal to each other and operated with a relative phase shift in time. Rotating field TMS (rfTMS) efficiently stimulates both cultured hippocampal networks and rat motor cortex, two neuronal systems that are notoriously difficult to excite magnetically. This opens the possibility of pharmacological and invasive TMS experiments in these model systems. Application of rfTMS to human subjects overcomes the orientation dependence of standard TMS. Thus, rfTMS yields optimal targeting of brain regions where correct orientation cannot be determined (e.g., via motor feedback) and will enable stimulation in brain regions where a preferred axonal orientation does not exist. PMID:24505266

Erosive arthritis in systemic lupus erythematosus: analysis of a distinct clinical and serological subset.

PubMed

Richter Cohen, M; Steiner, G; Smolen, J S; Isenberg, D A

1998-04-01

Erosive arthritis (EA) in systemic lupus erythematosus (SLE) can be debilitating and deforming with uncertain factors for risk, although antibodies to the A2 hnRNP core protein, known as anti-RA33, have been associated with EA. Two hundred patients under long-term follow-up for SLE were evaluated for EA and associated clinical and serological abnormalities. In addition, sera were tested in a masked fashion for anti-RA33 antibodies in a total of 60 patients: 10 with EA and 50 age-, sex- and ethnically matched controls. Ten of 200 (5%) patients with SLE, mainly non-white women, had EA. There were trends for increased renal involvement (P = 0.06), Sjögren's syndrome (P = 0.07) and Raynaud's phenomenon (P = 0.03) in patients with EA compared to those without EA. Rheumatoid factor (RF) was increased in patients with EA (P < 0.02), as were antibodies to double-stranded DNA (P < 0.05), Sm (P < 0.01) and La/SS-B (P < 0.001). Anti-RA33 antibodies were present in 70% with EA compared to 28% without EA (P < 0.05). RF correlated with anti-RA33 antibodies in patients with EA, but not with the presence of anti-RA33 alone. Thus, anti-RA33 antibodies may identify those patients with SLE who are at risk for EA, and an association with RF suggests a common immune response or pathological mechanism in autoimmune erosive joint disease.

Is topical anesthesia useful in noninvasive skin tightening using radiofrequency?

PubMed

Kushikata, Nobuharu; Negishi, Kei; Tezuka, Yukiko; Takeuchi, Kaori; Wakamatsu, Shingo

2005-05-01

The radiofrequency (RF) system has been applied to Asian skin for noninvasive skin tightening. The only drawback is the pain during the treatment. The relationships between the effectiveness of a topical anesthetic at various RF levels and the respective treatment results were compared and assessed after 3 months. Eighty-four females, ranging in age from 30 to 60 years, were divided into three groups of 28 subjects each. In all groups, the entire bilateral cheeks were treated. Group A underwent RF treatment (ThermaCool TC, Thermage, Hayward, CA, USA) with topical anesthesia and group B without anesthesia, and in group C, half of the face was treated with anesthesia and the other half was not. The degree of pain was recorded. Digital photographs of the patients pre- and post-treatment were objectively assessed by double-blinded physicians. Subjective assessment was performed with questionnaires. The average treatment levels for groups A and B were 14.13 and 14.02, respectively. Although anesthesia was useful for pain reduction, it did not allow a significant energy upgrade. In group C, 8 (28.6%) patients showed a statistically insignificant difference in the treatment levels, but not in the results, between the anesthetized and the unanesthetized sides. The use of anesthesia did not affect the final efficacy of the treatment compared with no anesthesia.

rf power system for thrust measurements of a helicon plasma source.

PubMed

Kieckhafer, Alexander W; Walker, Mitchell L R

2010-07-01

A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line. Second, the rf power cabinet was placed remotely in order to reduce vibration-induced noise in the thrust stand. Finally, a relationship between transmission line length and rf was developed, which allows good transmission of rf power from the matching network to the helicon antenna. The modified system was tested on a thrust measurement stand and showed that rf power has no statistically significant contribution to the thrust stand measurement.

CEBAF Superconducting Cavity RF Drive System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fugitt, Jock; Moore, Thomas

1987-03-01

The CEBAR RF system consists of 418 individual RF amplifier chains. Each superconducting cavity is phase locked to the master drive reference line to within 1 degree, and the cavity field gradient is regulated to within 1 part in 10 by a state-of-the-art RF control module. Precision, continuously adjustable, modulo 360 phase shifters are used to generate the individual phase references, and a compensated RF detector is used for level feedback. The close coupled digital system enhances system accuracy, provides self-calibration, and continuously checks the system for malfunction. Calibration curves, the operating program, and system history are stored in anmore » on board EEPROM. The RF power is generated by a 5Kw, water cooled, permanent magnet focused klystorn. The klystons are clustered in groups of 8 and powered from a common supply. RF power is transmitted to the accelerator sections by semiflexible waveguide.« less

Generation of multiple analog pulses with different duty cycles within VME control system for ICRH Aditya system

NASA Astrophysics Data System (ADS)

Joshi, Ramesh; Singh, Manoj; Jadav, H. M.; Misra, Kishor; Kulkarni, S. V.; ICRH-RF Group

2010-02-01

Ion Cyclotron Resonance Heating (ICRH) is a promising heating method for a fusion device due to its localized power deposition profile, a direct ion heating at high density, and established technology for high RF power generation and transmission at low cost. Multiple analog pulse with different duty cycle in master of digital pulse for Data acquisition and Control system for steady state RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya to produce pre ionization and second analog pulse will produce heating. The control system software is based upon single digital pulse operation for RF source. It is planned to integrate multiple analog pulses with different duty cycle in master of digital pulse for Data acquisition and Control system for RF ICRH System(RF ICRH DAC) to be used for operating of RF Generator in Aditya tokamak. The task of RF ICRH DAC is to control and acquisition of all ICRH system operation with all control loop and acquisition for post analysis of data with java based tool. For pre ionization startup as well as heating experiments using multiple RF Power of different powers and duration. The experiment based upon the idea of using single RF generator to energize antenna inside the tokamak to radiate power twise, out of which first analog pulse will produce pre ionization and second analog pulse will produce heating. The whole system is based on standard client server technology using tcp/ip protocol. DAC Software is based on linux operating system for highly reliable, secure and stable system operation in failsafe manner. Client system is based on tcl/tk like toolkit for user interface with c/c++ like environment which is reliable programming languages widely used on stand alone system operation with server as vxWorks real time operating system like environment. The paper is focused on the Data acquisition and monitoring system software on Aditya RF ICRH System with analog pulses in slave mode with digital pulse in master mode for control acquisition and monitoring and interlocking.

A Novel Cost-effective OFDM WDM-PON Radio Over Fiber System Employing FBG to Generate Optical mm-wave

NASA Astrophysics Data System (ADS)

Nguyen, HoangViet

2015-03-01

We have investigated and demonstrated a novel scheme to generate 2.5 Gbit/s 64 QAM orthogonal frequency division multiplexing (OFDM) signals for Radio Over Fiber (ROF) systems. We employ Fiber Bragg Grating (FBG) because the repetitive frequency of the RF source and the bandwidth of the optical modulator are largely reduced and the architecture of the ROF system is simpler. Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) has been considered as a promising solution for future broadband access networks. Principle of WDM-PON access network compatible with OFDM-ROF systems is investigated. This novel scheme which has multiple double-frequency technique to generate mm-wave signal to carry OFDM signals is a practical scheme to be applied for future broadband access networks.

Selective RF pulses in NMR and their effect on coupled and uncoupled spin systems

NASA Astrophysics Data System (ADS)

Slotboom, J.

1993-10-01

This thesis describes various aspects of the usage of shaped RF-pulses for volume selection and spectral editing. Contents: Introduction--The History of Magnetic Resonance in a Nutshell, and The Usage of RF Pulses in Contemporary MRS and MRI; Theoretical and Practical Aspects of Localized NMR Spectroscopy; The Effects of RF Pulse Shape Discretization on the Spatially Selective Performance; Design of Frequency-Selective RF Pulses by Optimizing a Small Number of Pulse Parameters; A Single-Shot Localization Pulse Sequence Suited for Coils with Inhomogeneous RF Fields Using Adiabatic Slice-Selective RF Pulses; The Bloch Equations for an AB System and the Design of Spin State Selective RF Pulses for Coupled Spin Systems; The Effects of Frequency Selective RF Pulses on J Coupled Spin-1/2 Systems; A Quantitative (1)H MRS in vivo Study of the Effects of L-Ornithine-L-Aspartate on the Development of Mild Encephalopathy Using a Single Shot Localization Technique Based on SAR Reduced Adiabatic 2(pi) Pulses.

Design and Calibration of an RF Actuator for Low-Level RF Systems

NASA Astrophysics Data System (ADS)

Geng, Zheqiao; Hong, Bo

2016-02-01

X-ray free electron laser (FEL) machines like the Linac Coherent Light Source (LCLS) at SLAC require high-quality electron beams to generate X-ray lasers for various experiments. Digital low-level RF (LLRF) systems are widely used to control the high-power RF klystrons to provide a highly stable RF field in accelerator structures for beam acceleration. Feedback and feedforward controllers are implemented in LLRF systems to stabilize or adjust the phase and amplitude of the RF field. To achieve the RF stability and the accuracy of the phase and amplitude adjustment, low-noise and highly linear RF actuators are required. Aiming for the upgrade of the S-band Linac at SLAC, an RF actuator is designed with an I/Qmodulator driven by two digital-to-analog converters (DAC) for the digital LLRF systems. A direct upconversion scheme is selected for RF actuation, and an on-line calibration algorithm is developed to compensate the RF reference leakage and the imbalance errors in the I/Q modulator, which may cause significant phase and amplitude actuation errors. This paper presents the requirements on the RF actuator, the design of the hardware, the calibration algorithm, and the implementation in firmware and software and the test results at LCLS.

rf power system for thrust measurements of a helicon plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieckhafer, Alexander W.; Walker, Mitchell L. R.

2010-07-15

A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line. Second, the rf power cabinet was placed remotely in order to reduce vibration-induced noise in the thrust stand. Finally, a relationship between transmission line length and rf was developed, which allows goodmore » transmission of rf power from the matching network to the helicon antenna. The modified system was tested on a thrust measurement stand and showed that rf power has no statistically significant contribution to the thrust stand measurement.« less

Development and study of charge sensors for fast charge detection in quantum dots

NASA Astrophysics Data System (ADS)

Thalakulam, Madhu

Charge detection at microsecond time-scales has far reaching consequences in both technology and in our understanding of electron dynamics in nanoscale devices such as quantum dots. Radio-frequency superconducting single electron transistors (RF-SET) and quantum point contacts (QPC) are ultra sensitive charge sensors operating near the quantum limit. The operation of RF-SETs outside the superconducting gap has been a topic of study; the sub-gap operation, especially in the presence of large quantum fluctuations of quasiparticles remains largely unexplored, both theoretically and experimentally. We have investigated the effects of quantum fluctuations of quasiparticles on the operation of RF-SETs for large values of the quasiparticle cotunneling parameter alpha = 8EJ/Ec, where EJ and Ec are the Josephson and charging energies. We find that, for alpha > 1, sub-gap RF-SET operation is still feasible despite quantum fluctuations that wash out quasiparticle tunneling thresholds. Such RF-SETs show linearity and signal-to-noise ratio superior to those obtained when quantum fluctuations are weak, while still demonstrating excellent charge sensitivity. We have operated a QPC charge detector in a radio frequency mode that allows fast charge detection in a bandwidth of several megahertz. The noise limiting the sensitivity of the charge detector is not the noise of a secondary amplifier, but the non-equilibrium device noise of the QPC itself. The noise power averaged over a measurement bandwidth of about 10MHz around the carrier frequency is in agreement with the theory of photon-assisted shot noise. Frequency-resolved measurements, however show several significant discrepancies with the theoretical predictions. The measurement techniques developed can also be used to investigate the noise of other semiconductor nanostructures such as quantum dots in the Kondo regime. A study of the noise characteristics alone can not determine whether the device is operating at the quantum limit; a characterization of back action is also necessary. The inelastic current through a double quantum dot system (DQD) is sensitive to the spectral density of voltage fluctuations in its electromagnetic environment. Electrical transport studies on a DQD system electrostatically coupled to an SET shows qualitative evidence of back-action of SET. The design and fabrication of a few electron DQD device with integrated RF-SET and QPC charge sensors for the study of back action of the sensors and real-time electron dynamics in the DQD are also discussed.

Ion acceleration and non-Maxwellian electron distributions in a low collisionality, high power helicon plasma source

NASA Astrophysics Data System (ADS)

Li, Yan; Sung, Yung-Ta; Scharer, John

2015-11-01

Ion acceleration through plasma double layer and non-Maxwellian two temperature electron distributions have been observed in Madison Helicon Experiment (MadHeX) operated in high RF power (>1000 W) and low Ar pressure (0.17 mtorr) inductive mode. By applying Optical Emission Spectroscopy (OES) cross-checked with an RF-compensated Langmuir probe (at 13.56 MHz and its second and third harmonics), the fast (>80 eV), untrapped electrons downstream of the double layer have a higher temperature of 13 eV than the trapped bulk electrons upstream with a temperature of 4 eV. The reduction of plasma potential and density observed in the double layer region require an upstream temperature ten times the measured 4 eV if occurring via Boltzmann ambipolar expansion. The hot tail electrons of the non-Maxwellian electron distribution affect the formation and the potential drop of the double layer region. The mechanism behind this has been explored via several non-invasive plasma diagnostics tools. The OES measured electron temperatures and densities are also cross-checked with Atomic Data and Analysis Structure (ADAS) and a millimeter wave interferometer respectively. The IEDF is measured by a four-grid RPA and also cross-checked with argon 668 nm Laser Induced Fluorescence (LIF). An emissive probe has been used to measure the plasma potential.

Impact of device engineering on analog/RF performances of tunnel field effect transistors

NASA Astrophysics Data System (ADS)

Vijayvargiya, V.; Reniwal, B. S.; Singh, P.; Vishvakarma, S. K.

2017-06-01

The tunnel field effect transistor (TFET) and its analog/RF performance is being aggressively studied at device architecture level for low power SoC design. Therefore, in this paper we have investigated the influence of the gate-drain underlap (UL) and different dielectric materials for the spacer and gate oxide on DG-TFET (double gate TFET) and its analog/RF performance for low power applications. Here, it is found that the drive current behavior in DG-TFET with a UL feature while implementing dielectric material for the spacer is different in comparison to that of DG-FET. Further, hetero gate dielectric-based DG-TFET (HGDG-TFET) is more resistive against drain-induced barrier lowering (DIBL) as compared to DG-TFET with high-k (HK) gate dielectric. Along with that, as compared to DG-FET, this paper also analyses the attributes of UL and dielectric material on analog/RF performance of DG-TFET in terms of transconductance (gm ), transconductance generation factor (TGF), capacitance, intrinsic resistance (Rdcr), cut-off frequency (F T), and maximum oscillation frequency (F max). The LK spacer-based HGDG-TFET with a gate-drain UL has the potential to improve the RF performance of device.

Effects of short-term radiation emitted by WCDMA mobile phones on teenagers and adults

PubMed Central

2014-01-01

Background With the rapid increasing use of third generation (3 G) mobile phones, social concerns have arisen concerning the possible health effects of radio frequency-electromagnetic fields (RF-EMFs) emitted by wideband code division multiple access (WCDMA) mobile phones in humans. The number of people, who complain of various symptoms such as headache, dizziness, and fatigue, has also increased. Recently, the importance of researches on teenagers has been on the rise. However, very few provocation studies have examined the health effects of WCDMA mobile phone radiation on teenagers. Methods In this double-blind study, two volunteer groups of 26 adults and 26 teenagers were simultaneously investigated by measuring physiological changes in heart rate, respiration rate, and heart rate variability for autonomic nervous system (ANS), eight subjective symptoms, and perception of RF-EMFs during sham and real exposure sessions to verify its effects on adults and teenagers. Experiments were conducted using a dummy phone containing a WCDMA module (average power, 250 mW at 1950 MHz; specific absorption rate, 1.57 W/kg) within a headset placed on the head for 32 min. Results Short-term WCDMA RF-EMFs generated no significant changes in ANS, subjective symptoms or the percentages of those who believed they were being exposed in either group. Conclusions Considering the analyzed physiological data, the subjective symptoms surveyed, and the percentages of those who believed they were being exposed, 32 min of RF radiation emitted by WCDMA mobile phones demonstrated no effects in either adult or teenager subjects. PMID:24886241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Champion, Mark S; Dean, Robert A; Galambos, John D

The Proton Power Upgrade Project is underway at the Spallation Neutron Source at Oak Ridge National Labor-atory and will double the proton beam power capability from 1.4 MW to 2.8 MW to provide increased neutron intensity at the first target station and to support future operation of the second target station. This will be ac-complished by increasing the beam energy to 1.3 GeV and the beam current to 38 mA (average during the macropulse). Installation of 28 additional superconduct-ing cavities and their associated technical systems will provide for the energy increase. Increased beam loading throughout the accelerator will be accommodatedmore » primar-ily through the use of existing margin in the RF systems and the installation of 700 kW klystrons to power the new superconducting cavities. Upgrades of a few existing RF stations may also be needed. The injection and ex-traction regions of the accumulator ring will be upgraded, a ring to second target station tunnel stub will be con-structed, and a 2 MW target will be developed for the first target station. The project anticipates attainment of Criti-cal Decision 1 in 2017 to ratify the project conceptual design and cost range.« less

Phase stable RF transport system

DOEpatents

Curtin, Michael T.; Natter, Eckard F.; Denney, Peter M.

1992-01-01

An RF transport system delivers a phase-stable RF signal to a load, such as an RF cavity of a charged particle accelerator. A circuit generates a calibration signal at an odd multiple frequency of the RF signal where the calibration signal is superimposed with the RF signal on a common cable that connects the RF signal with the load. Signal isolating diplexers are located at both the RF signal source end and load end of the common cable to enable the calibration to be inserted and extracted from the cable signals without any affect on the RF signal. Any phase shift in the calibration signal during traverse of the common cable is then functionally related to the phase shift in the RF signal. The calibration phase shift is used to control a phase shifter for the RF signal to maintain a stable RF signal at the load.

Mobile phone signal exposure triggers a hormesis-like effect in Atm+/+ and Atm-/- mouse embryonic fibroblasts.

PubMed

Sun, Chuan; Wei, Xiaoxia; Fei, Yue; Su, Liling; Zhao, Xinyuan; Chen, Guangdi; Xu, Zhengping

2016-11-18

Radiofrequency electromagnetic fields (RF-EMFs) have been classified by the International Agency for Research on Cancer as possible carcinogens to humans; however, this conclusion is based on limited epidemiological findings and lacks solid support from experimental studies. In particular, there are no consistent data regarding the genotoxicity of RF-EMFs. Ataxia telangiectasia mutated (ATM) is recognised as a chief guardian of genomic stability. To address the debate on whether RF-EMFs are genotoxic, we compared the effects of 1,800 MHz RF-EMF exposure on genomic DNA in mouse embryonic fibroblasts (MEFs) with proficient (Atm +/+ ) or deficient (Atm -/- ) ATM. In Atm +/+ MEFs, RF-EMF exposure for 1 h at an average special absorption rate of 4.0 W/kg induced significant DNA single-strand breaks (SSBs) and activated the SSB repair mechanism. This effect reduced the DNA damage to less than that of the background level after 36 hours of exposure. In the Atm -/- MEFs, the same RF-EMF exposure for 12 h induced both SSBs and double-strand breaks and activated the two repair processes, which also reduced the DNA damage to less than the control level after prolonged exposure. The observed phenomenon is similar to the hormesis of a toxic substance at a low dose. To the best of our knowledge, this study is the first to report a hormesis-like effect of an RF-EMF.

A Novel Highly Bioavailable Curcumin Formulation Improves Symptoms and Diagnostic Indicators in Rheumatoid Arthritis Patients: A Randomized, Double-Blind, Placebo-Controlled, Two-Dose, Three-Arm, and Parallel-Group Study.

PubMed

Amalraj, Augustine; Varma, Karthik; Jacob, Joby; Divya, Chandradhara; Kunnumakkara, Ajaikumar B; Stohs, Sidney J; Gopi, Sreeraj

2017-10-01

Rheumatoid arthritis (RA) is an autoimmune, chronic systemic inflammatory disorder. The long-term use of currently available drugs for the treatment of RA has many potential side effects. Natural phytonutrients may serve as alternative strategies for the safe and effective treatment of RA, and curcuminoids have been used in Ayurvedic medicine for the treatment of inflammatory conditions for centuries. In this study, a novel, highly bioavailable form of curcumin in a completely natural turmeric matrix was evaluated for its ability to improve the clinical symptoms of RA. A randomized, double-blind, placebo-controlled, three-arm, parallel-group study was conducted to evaluate the comparative efficacy of two different doses of curcumin with that of a placebo in active RA patients. Twelve patients in each group received placebo, 250 or 500 mg of the curcumin product twice daily for 90 days. The responses of the patients were assessed using the American College of Rheumatology (ACR) response, visual analog scale (VAS), C-reactive protein (CRP), Disease Activity Score 28 (DAS28), erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF) values. RA patients who received the curcumin product at both low and high doses reported statistically significant changes in their clinical symptoms at the end of the study. These observations were confirmed by significant changes in ESR, CPR, and RF values in patients receiving the study product compared to baseline and placebo. The results indicate that this novel curcumin in a turmeric matrix acts as an analgesic and anti-inflammatory agent for the management of RA at a dose as low as 250 mg twice daily as evidenced by significant improvement in the ESR, CRP, VAS, RF, DAS28, and ACR responses compared to placebo. Both doses of the study product were well tolerated and without side effects.

T-gate aligned nanotube radio frequency transistors and circuits with superior performance.

PubMed

Che, Yuchi; Lin, Yung-Chen; Kim, Pyojae; Zhou, Chongwu

2013-05-28

In this paper, we applied self-aligned T-gate design to aligned carbon nanotube array transistors and achieved an extrinsic current-gain cutoff frequency (ft) of 25 GHz, which is the best on-chip performance for nanotube radio frequency (RF) transistors reported to date. Meanwhile, an intrinsic current-gain cutoff frequency up to 102 GHz is obtained, comparable to the best value reported for nanotube RF transistors. Armed with the excellent extrinsic RF performance, we performed both single-tone and two-tone measurements for aligned nanotube transistors at a frequency up to 8 GHz. Furthermore, we utilized T-gate aligned nanotube transistors to construct mixing and frequency doubling analog circuits operated in gigahertz frequency regime. Our results confirm the great potential of nanotube-based circuit applications and indicate that nanotube transistors are promising building blocks in high-frequency electronics.

Acute effects of mobile phone radiations on subtle energy levels of teenagers using electrophotonic imaging technique: A randomized controlled study

PubMed Central

Bhargav, Hemant; Srinivasan, TM; Bista, Suman; Mooventhan, A; Suresh, Vandana; Hankey, Alex; Nagendra, HR

2017-01-01

Background: Mobile phones induce radio frequency electromagnetic field (RF-EMF) which has been found to affect subtle energy levels of adults through Electrophotonic Imaging (EPI) technique in a previous pilot study. Materials and Methods: We enrolled 61 healthy right-handed healthy teenagers (22 males and 39 females) in the age range of 17.40 ± 0.24 years from educational institutes in Bengaluru. Subjects were randomly divided into two groups: (1) (mobile phone in ON mode [MPON] at right ear) and (2) mobile phone in OFF mode (MPOF). Subtle energy levels of various organs of the subjects were measured using gas discharge visualization Camera Pro device, in double-blind conditions, at two points of time: (1) baseline and (2) after 15 min of MPON/MPOF exposure. As the data were found normally distributed, paired and independent samples t-test were applied to perform within and between group comparisons, respectively. Results: The subtle energy levels were significantly reduced after RF-EMF exposure in MPON group as compared to MPOF group for following areas: (a) Pancreas (P = 0.001), (b) thyroid gland (P = 0.002), (c) cerebral cortex (P < 0.01), (d) cerebral vessels (P < 0.05), (e) hypophysis (P = 0.013), (f) left ear and left eye (P < 0.01), (g) liver (P < 0.05), (h) right kidney (P < 0.05), (i) spleen (P < 0.04), and (j) immune system (P < 0.02). Conclusion: Fifteen minutes of RF-EMF exposure exerted quantifiable effects on subtle energy levels of endocrine glands, nervous system, liver, kidney, spleen, and immune system of healthy teenagers. Future studies should try to correlate these findings with respective biochemical markers and standard radio-imaging techniques. PMID:28149063

Systematic analysis of CMOS-micromachined inductors with application to mixer matching circuits

NASA Astrophysics Data System (ADS)

Wu, Jerry Chun-Li

The growing demand for consumer voice and data communication systems and military communication applications has created a need for low-power, low-cost, high-performance radio-frequency (RF) front-end. To achieve this goal, bringing passive components, especially inductors, to silicon is imperative. On-chip passive components such as inductors and capacitors generally enhance the reliability and efficiency of silicon-integrated RF cells. They can provide circuit solutions with superior performance and contribute to a higher level of integration. With passive components on chip, there is a great opportunity to have transformers, filters, and matching networks on chip. However, inductors on silicon have a low quality factor (Q) due to both substrate and metal loss. This dissertation demonstrates the systematic analysis of inductors fabricated using standard complementary metal-oxide-semiconductor (CMOS) and micro-electro-mechanical (MEMS) system technologies. We report system-on-chip inductor modeling, simulation, and measurements of effective inductance and quality factors. In this analysis methodology, a number of systematic simulations are performed on regular and micromachined inductors with different parameters such as spiral topology, number of turns, outer diameter, thickness, and percentage of substrate removed by using micromachining technologies. Three different novel support structures of the micromachined spiral inductor are proposed, analyzed, and implemented for larger size suspended inductors. The sensitivity of the structure support and different degree of substrate etching by post-processing is illustrated. The results provide guidelines for the selection of inductor parameters, post-processing methodologies, and its spiral supports to meet the RF design specifications and the stability requirements for mobile communication. The proposed CMOS-micromachined inductor is used in a low cost-effective double-balanced Gilbert mixer with on-chip matching network. The integrated mixer inductor was implemented and tested to prove the concept.

Compact Power Conditioning and RF Systems for a High Power RF Source

DTIC Science & Technology

2008-12-01

RF systems have increasing potential for application by the Army. High power RF, or high power microwave ( HPM ), systems can disrupt or disable...that are small, lightweight, portable, and use an independent energy source. The resulting system will be able to produce HPM from a compact package...The consortium was formed to advance the technology of the components required for a compact HPM source with the final goal of full system

Heart Rate Detection During Sleep Using a Flexible RF Resonator and Injection-Locked PLL Sensor.

PubMed

Kim, Sung Woo; Choi, Soo Beom; An, Yong-Jun; Kim, Byung-Hyun; Kim, Deok Won; Yook, Jong-Gwan

2015-11-01

Novel nonintrusive technologies for wrist pulse detection have been developed and proposed as systems for sleep monitoring using three types of radio frequency (RF) sensors. The three types of RF sensors for heart rate measurement on wrist are a flexible RF single resonator, array resonators, and an injection-locked PLL resonator sensor. To verify the performance of the new RF systems, we compared heart rates between presleep time and postsleep onset time. Heart rates of ten subjects were measured using the RF systems during sleep. All three RF devices detected heart rates at 0.2 to 1 mm distance from the skin of the wrist over clothes made of cotton fabric. The wrist pulse signals of a flexible RF single resonator were consistent with the signals obtained by a portable piezoelectric transducer as a reference. Then, we confirmed that the heart rate after sleep onset time significantly decreased compared to before sleep. In conclusion, the RF system can be utilized as a noncontact nonintrusive method for measuring heart rates during sleep.

Circulation system for flowing uranium hexafluoride cavity reactor experiments

NASA Technical Reports Server (NTRS)

Jaminet, J. F.; Kendall, J. S.

1976-01-01

Research related to determining the feasibility of producing continuous power from fissile fuel in the gaseous state is presented. The development of three laboratory-scale flow systems for handling gaseous UF6 at temperatures up to 500 K, pressure up to approximately 40 atm, and continuous flow rates up to approximately 50g/s is presented. A UF6 handling system fabricated for static critical tests currently being conducted is described. The system was designed to supply UF6 to a double-walled aluminum core canister assembly at temperatures between 300 K and 400 K and pressure up to 4 atm. A second UF6 handling system designed to provide a circulating flow of up to 50g/s of gaseous UF6 in a closed-loop through a double-walled aluminum core canister with controlled temperature and pressure is described. Data from flow tests using UF6 and UF6/He mixtures with this system at flow rates up to approximately 12g/s and pressure up to 4 atm are presented. A third UF6 handling system fabricated to provide a continuous flow of UF6 at flow rates up to 5g/s and at pressures up to 40 atm for use in rf-heated, uranium plasma confinement experiments is described.

Electromagnetic radiation and behavioural response of ticks: an experimental test.

PubMed

Vargová, Blažena; Majláth, Igor; Kurimský, Juraj; Cimbala, Roman; Kosterec, Michal; Tryjanowski, Piotr; Jankowiak, Łukasz; Raši, Tomáš; Majláthová, Viktória

2018-05-01

Factors associated with the increased usage of electronic devices, wireless technologies and mobile phones nowadays are present in increasing amounts in our environment. All living organisms are constantly affected by electromagnetic radiation which causes serious environmental pollution. The distribution and density of ticks in natural habitats is influenced by a complex of abiotic and biotic factors. Exposure to radio-frequency electromagnetic field (RF-EMF) constitutes a potential cause altering the presence and distribution of ticks in the environment. Our main objective was to determine the affinity of Dermacentor reticulatus ticks towards RF-EMF exposure. Originally designed and constructed radiation-shielded tube (RST) test was used to test the affinity of ticks under controlled laboratory conditions. All test were performed in an electromagnetic compatibility laboratory in an anechoic chamber. Ticks were irradiated using a Double-Ridged Waveguide Horn Antenna to RF-EMF at 900 and 5000 MHz, 0 MHz was used as control. The RF-EMF exposure to 900 MHz induced a higher concentration of ticks on irradiated arm of RST as opposed to the RF-EMF at 5000 MHz, which caused an escape of ticks to the shielded arm. This study represents the first experimental evidence of RF-EMF preference in D. reticulatus. The projection of obtained results to the natural environment could help assess the risk of tick borne diseases and could be a tool of preventive medicine.

J-Refocused Coherence Transfer Spectroscopic Imaging at 7 T in Human Brain

PubMed Central

Pan, J.W.; Avdievich, N.; Hetherington, H.P.

2013-01-01

Short echo spectroscopy is commonly used to minimize signal modulation due to J-evolution of the cerebral amino acids. However, short echo acquisitions suffer from high sensitivity to macromolecules which make accurate baseline determination difficult. In this report, we describe implementation at 7 T of a double echo J-refocused coherence transfer sequence at echo time (TE) of 34 msec to minimize J-modulation of amino acids while also decreasing interfering macromolecule signals. Simulation of the pulse sequence at 7 T shows excellent resolution of glutamate, glutamine, and N-acetyl aspartate. B1 sufficiency at 7 T for the double echo acquisition is achieved using a transceiver array with radiofrequency (RF) shimming. Using an alternate RF distribution to minimize receiver phase cancellation in the transceiver, accurate phase determination for the coherence transfer is achieved with rapid single scan calibration. This method is demonstrated in spectroscopic imaging mode with n = 5 healthy volunteers resulting in metabolite values consistent with literature and in a patient with epilepsy. PMID:20648684

Observation of warm, higher energy electrons transiting a double layer in a helicon plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sung, Yung-Ta, E-mail: ysung2@wisc.edu; Li, Yan; Scharer, John E.

2015-03-15

Measurements of an inductive RF helicon argon plasma double layer with two temperature electron distributions including a fast (>80 eV) tail are observed at 0.17 mTorr Ar pressure. The fast, untrapped electrons observed downstream of the double layer have a higher temperature (13 eV) than the trapped (T{sub e} = 4 eV) electrons. The reduction of plasma potential and density observed in the double layer region would require an upstream temperature ten times the measured 4 eV if occurring via Boltzmann ambipolar expansion. The experimental observation in Madison helicon experiment indicates that fast electrons with substantial density fractions can be created at low helicon operating pressures.

Pantechnik new superconducting ion source: PantechniK Indian Superconducting Ion Source.

PubMed

Gaubert, G; Bieth, C; Bougy, W; Brionne, N; Donzel, X; Leroy, R; Sineau, A; Vallerand, C; Villari, A C C; Thuillier, T

2012-02-01

The new ECR ion source PantechniK Indian Superconducting Ion Source (PKISIS) was recently commissioned at Pantechnik. Three superconducting coils generate the axial magnetic field configuration, while the radial magnetic field is done with the multi-layer permanent magnets. Special care was devoted to the design of the hexapolar structure, allowing a maximum magnetic field of 1.32 T at the wall of the 82 mm diameter plasma chamber. The three superconducting coils using low temperature superconducting wires are cooled by a single double stage cryo-cooler (4.2 K). Cryogen-free technology is used, providing reliability and easy maintenance at low cost. The maximum installed RF power (18.0 GHz) is of 2 kW. Metallic beams can be produced with an oven (T(max) = 1400 °C) installed with an angle of 5° with respect to the source axis or a sputtering system, mounted on the axis of the source. The beam extraction system is constituted of three electrodes in accel-decel configuration. The new source of Pantechnik is conceived for reaching optimum performances at 18 GHz RF frequencies. PKISIS magnetic fields are 2.1 T axial B(inj) and 1.32 T radial field in the wall, variable B(min) with an independent coil and a large and opened extraction region. Moreover, PKISIS integrates modern design concepts, like RF direct injection (2 kW availability), dc-bias moving disk, out-of-axis oven and axial sputtering facility for metal beams. Finally, PKISIS is also conceived in order to operate in a high-voltage platform with minor power consumption.

SNP-markers in Allium species to facilitate introgression breeding in onion.

PubMed

Scholten, Olga E; van Kaauwen, Martijn P W; Shahin, Arwa; Hendrickx, Patrick M; Keizer, L C Paul; Burger, Karin; van Heusden, Adriaan W; van der Linden, C Gerard; Vosman, Ben

2016-08-31

Within onion, Allium cepa L., the availability of disease resistance is limited. The identification of sources of resistance in related species, such as Allium roylei and Allium fistulosum, was a first step towards the improvement of onion cultivars by breeding. SNP markers linked to resistance and polymorphic between these related species and onion cultivars are a valuable tool to efficiently introgress disease resistance genes. In this paper we describe the identification and validation of SNP markers valuable for onion breeding. Transcriptome sequencing resulted in 192 million RNA seq reads from the interspecific F1 hybrid between A. roylei and A. fistulosum (RF) and nine onion cultivars. After assembly, reliable SNPs were discovered in about 36 % of the contigs. For genotyping of the interspecific three-way cross population, derived from a cross between an onion cultivar and the RF (CCxRF), 1100 SNPs that are polymorphic in RF and monomorphic in the onion cultivars (RF SNPs) were selected for the development of KASP assays. A molecular linkage map based on 667 RF-SNP markers was constructed for CCxRF. In addition, KASP assays were developed for 1600 onion-SNPs (SNPs polymorphic among onion cultivars). A second linkage map was constructed for an F2 of onion x A. roylei (F2(CxR)) that consisted of 182 onion-SNPs and 119 RF-SNPs, and 76 previously mapped markers. Markers co-segregating in both the F2(CxR) and the CCxRF population were used to assign the linkage groups of RF to onion chromosomes. To validate usefulness of these SNP markers, QTL mapping was applied in the CCxRF population that segregates for resistance to Botrytis squamosa and resulted in a QTL for resistance on chromosome 6 of A. roylei. Our research has more than doubled the publicly available marker sequences of expressed onion genes and two onion-related species. It resulted in a detailed genetic map for the interspecific CCxRF population. This is the first paper that reports the detection of a QTL for resistance to B. squamosa in A. roylei.

Tunable photonic band gaps and optical nonreciprocity by an RF-driving ladder-type system in moving optical lattice

NASA Astrophysics Data System (ADS)

Ba, Nuo; Zhong, Xin; Wang, Lei; Fei, Jin-You; Zhang, Yan; Bao, Qian-Qian; Xiao, Li

2018-03-01

We investigate photonic transport properties of the 1D moving optical lattices filled with vast cold atoms driven into a four-level ladder-type system and obtain dynamically controlled photonic bandgaps and optical nonreciprocity. It is found that the two obvious optical nonreciprocity can be generated at two well-developed photonic bandgaps based on double dark states in the presence of a radio-frequency field. However, when the radio-frequency field is absence, the only one induced photonic bandgaps with distinguishing optical nonreciprocity can be opened up via single dark state. Dynamic control of the induced photonic bandgaps and optical nonreciprocity could be exploited to achieve all-optical diodes and routing for quantum information networks.

The application of "double isolation" in Fourier transform ion cyclotron resonance sustained off-resonance irradiation collisionally-induced dissociation tandem mass spectrometry to remove labile isobaric impurities.

PubMed

Gates, Paul J; Lopes, Norberto P; Pinto, Emani; Colepicolo, Pio; Cardozo, Karina H M

2011-01-01

This study reports the application of "double isolation" in sustained off-resonance irradiation collisionally-induced dissociation tandem mass spectrometry (SORI-CID-MS/MS) to remove radio- frequency (RF) fragment ions of very close mass isobaric ions (0.02 m/z apart). Analyses were performed with a fraction of a biological extract isolated from a macroalgae containing the mycosporine-like amino acid asterina-330. Direct isolation of the precursor ion by narrowing the isolation window proved ineffective as it impinged upon the required ion thus substantially reducing its intensity. By increasing the correlated sweep time, ejection efficiency of the isolation was improved, but caused the unwanted side-effect of RF fragmentation of labile ions. Finally, by skipping the ion activation step and performing a second isolation (in the MS(3) module) the RF fragments from the first isolation were removed leaving a very pure isolation of the required precursor ion and allowed a very clean CID fragmentation. We demonstrated that the m/z 272.1351 ion is derived from the loss of NH(3) from m/z 289.1620 isobaric impurity and is not related to asterina-330. This application represents a powerful tool to remove unwanted ions in the MS/MS spectrum that result from fragmentation of isobaric ions.

No increased sensitivity in brain activity of adolescents exposed to mobile phone-like emissions.

PubMed

Loughran, S P; Benz, D C; Schmid, M R; Murbach, M; Kuster, N; Achermann, P

2013-07-01

To examine the potential sensitivity of adolescents to radiofrequency electromagnetic field (RF EMF) exposures, such as those emitted by mobile phones. In a double-blind, randomized, crossover design, 22 adolescents aged 11-13 years (12 males) underwent three experimental sessions in which they were exposed to mobile phone-like RF EMF signals at two different intensities, and a sham session. During exposure cognitive tasks were performed and waking EEG was recorded at three time-points subsequent to exposure (0, 30 and 60 min). No clear significant effects of RF EMF exposure were found on the waking EEG or cognitive performance. Overall, the current study was unable to demonstrate exposure-related effects previously observed on the waking EEG in adults, and also provides further support for a lack of an influence of mobile phone-like exposure on cognitive performance. Adolescents do not appear to be more sensitive than adults to mobile phone RF EMF emissions. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

High-power microstrip RF switch

NASA Technical Reports Server (NTRS)

Choi, S. D.

1971-01-01

A microstrip-type single-pole double-throw (SPDT) switch whose RF and bias portions contain only a metallized alumina substrate and two PIN diodes has been developed. A technique developed to eliminate the dc blocking capacitors needed for biasing the diodes is described. These capacitors are extra components and could lower the reliability significantly. An SPDT switch fabricated on a 5.08 x 5.08 x 0.127-cm (2 x 2 x 0.050-in.) substrate has demonstrated an RF power-handling capability greater than 50 W at S-band. The insertion loss is less than 0.25 db and the input-to-off port isolation is greater than 36 db over a bandwidth larger than 30 MHz. The input voltage standing-wave ratio is lower than 1.07 over the same bandwidth. Theoretical development of the switch characteristics and experimental results, which are in good agreement with theory, are presented.

Development of sub-100 femtosecond timing and synchronization system

NASA Astrophysics Data System (ADS)

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (˜0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Development of sub-100 femtosecond timing and synchronization system.

PubMed

Lin, Zhenyang; Du, Yingchao; Yang, Jin; Xu, Yilun; Yan, Lixin; Huang, Wenhui; Tang, Chuanxiang; Huang, Gang; Du, Qiang; Doolittle, Lawrence; Wilcox, Russell; Byrd, John

2018-01-01

The precise timing and synchronization system is an essential part for the ultra-fast electron and X-ray sources based on the photocathode injector where strict synchronization among RF, laser, and beams are required. In this paper, we present an integrated sub-100 femtosecond timing and synchronization system developed and demonstrated recently in Tsinghua University based on the collaboration with Lawrence Berkeley National Lab. The timing and synchronization system includes the fiber-based CW carrier phase reference distribution system for delivering stabilized RF phase reference to multiple receiver clients, the Low Level RF (LLRF) control system to monitor and generate the phase and amplitude controllable pulse RF signal, and the laser-RF synchronization system for high precision synchronization between optical and RF signals. Each subsystem is characterized by its blocking structure and is also expansible. A novel asymmetric calibration sideband signal method was proposed for eliminating the non-linear distortion in the optical synchronization process. According to offline and online tests, the system can deliver a stable signal to each client and suppress the drift and jitter of the RF signal for the accelerator and the laser oscillator to less than 100 fs RMS (∼0.1° in 2856 MHz frequency). Moreover, a demo system with a LLRF client and a laser-RF synchronization client is deployed and operated successfully at the Tsinghua Thomson scattering X-ray source. The beam-based jitter measurement experiments have been conducted to evaluate the overall performance of the system, and the jitter sources are discussed.

Precursor and Neutral Loss Scans in an RF Scanning Linear Quadrupole Ion Trap

NASA Astrophysics Data System (ADS)

Snyder, Dalton T.; Szalwinski, Lucas J.; Schrader, Robert L.; Pirro, Valentina; Hilger, Ryan; Cooks, R. Graham

2018-03-01

Methodology for performing precursor and neutral loss scans in an RF scanning linear quadrupole ion trap is described and compared to the unconventional ac frequency scan technique. In the RF scanning variant, precursor ions are mass selectively excited by a fixed frequency resonance excitation signal at low Mathieu q while the RF amplitude is ramped linearly to pass ions through the point of excitation such that the excited ion's m/z varies linearly with time. Ironically, a nonlinear ac frequency scan is still required for ejection of the product ions since their frequencies vary nonlinearly with the linearly varying RF amplitude. In the case of the precursor scan, the ejection frequency must be scanned so that it is fixed on a product ion m/z throughout the RF scan, whereas in the neutral loss scan, it must be scanned to maintain a constant mass offset from the excited precursor ions. Both simultaneous and sequential permutation scans are possible; only the former are demonstrated here. The scans described are performed on a variety of samples using different ionization sources: protonated amphetamine ions generated by nanoelectrospray ionization (nESI), explosives ionized by low-temperature plasma (LTP), and chemical warfare agent simulants sampled from a surface and analyzed with swab touch spray (TS). We lastly conclude that the ac frequency scan variant of these MS/MS scans is preferred due to electronic simplicity. In an accompanying manuscript, we thus describe the implementation of orthogonal double resonance precursor and neutral loss scans on the Mini 12 using constant RF voltage. [Figure not available: see fulltext.

RF switching network: a novel technique for IR sensing

NASA Astrophysics Data System (ADS)

Mechtel, Deborah M.; Jenkins, R. Brian; Joyce, Peter J.; Nelson, Charles L.

2016-05-01

Rapid sensing of near infrared (IR) energy on a composite structure would provide information that could mitigate damage to composite structures. This paper describes a novel technique that implements photoconductive sensors in a radio frequency (RF) switching network designed to locate in real time the position and intensity of IR radiation incident on a composite structure. In the implementation described here, photoconductive sensors act as rapid response switches in a two layer RF network embedded in an FR-4 laminate. To detect radiation, phosphorous doped silicon photoconductive sensors are inserted in GHz range RF transmission lines. Photoconductive sensors use semiconductor materials that are optically sensitive at material dependent wavelengths. Incident radiation at the appropriate wavelength produces hole-electron pairs, so that the semiconductor becomes a conductor. By permitting signal propagation only when a sensor is illuminated, the RF signals are selectively routed from the lower layer transmission lines to the upper layer lines, thereby pinpointing the location and strength of incident radiation on a structure. Simulations based on a high frequency 3D planar electromagnetics model are presented and compared to experimental results. Experimental results are described for GHz range RF signal control for 300 mW and 180 mW incident energy from 975 nm and 1060 nm wavelength lasers respectively, where upon illumination, RF transmission line signal output power doubled when compared to non-illuminated results. Experimental results are reported for 100 W incident energy from a 1060 nm laser. Test results illustrate that real-time signal processing would permit a structure or vehicle to be controlled in response to incident radiation

Doubling The Intensity Of An ERL Based Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andrew Hutton

2005-05-01

A light source based on an Energy Recovered Linac (ERL) [1] consists of a superconducting linac and a transfer line that includes wigglers and undulators to produce the synchrotron light. The transfer line brings the electron bunches back to the beginning of the linac so that their energy can be recovered when they traverse the linac a second time, {lambda}/2 out of RF phase. There is another interesting condition when the length of the transfer line is (n {+-} 1/4) {lambda}. In this case, the electrons drift through on the zero RF crossing, and make a further pass around themore » transfer line, effectively doubling the circulating current in the wigglers and undulators. On the third pass through the linac, they will be decelerated and their energy recovered. The longitudinal focusing at the zero crossing is a problem, but it can be canceled if the drifting beam sees a positive energy gradient for the first half of the linac and a negative gradient for the second half (or vice versa). This paper presents a proposal to use a double chicane at the center of the linac to provide this focusing inversion for the drifting beam while leaving the accelerating and decelerating beams on crest. [1] G. R. Neil, et al, Phys. Rev. Let. 84, 662 2000« less

Long pulse EBW start-up experiments in MAST

DOE PAGES

Shevchenko, V. F.; Baranov, Y. F.; Bigelow, T.; ...

2015-03-12

Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (O) mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even inmore » cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.« less

Long pulse EBW start-up experiments in MAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shevchenko, V. F.; Baranov, Y. F.; Bigelow, T.

Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (O) mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even inmore » cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.« less

Long Pulse EBW Start-up Experiments in MAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shevchenko, V. F.; Bigelow, Tim S; Caughman, J. B. O.

Start-up technique reported here relies on a double mode conversion (MC) for electron Bernstein wave (EBW) excitation. It consists of MC of the ordinary (0) mode, entering the plasma from the low field side of the tokamak, into the extraordinary (X) mode at a mirror-polarizer located at the high field side. The X mode propagates back to the plasma, passes through electron cyclotron resonance (ECR) and experiences a subsequent X to EBW MC near the upper hybrid resonance (UHR). Finally the excited EBW mode is totally absorbed at the Doppler shifted ECR. The absorption of EBW remains high even inmore » cold rarefied plasmas. Furthermore, EBW can generate significant plasma current giving the prospect of a fully solenoid-free plasma start-up. First experiments using this scheme were carried out on MAST [1]. Plasma currents up to 33 kA have been achieved using 28 GHz 100kW 90ms RF pulses. Recently experimental results were extended to longer RF pulses showing further increase of plasma currents generated by RF power alone. A record current of 73kA has been achieved with 450ms RF pulse of similar power. The current drive enhancement was mainly achieved due to RF pulse extension and further optimisation of the start-up scenario.« less

Microelectronic bioinstrumentation systems

NASA Technical Reports Server (NTRS)

Ko, W. H.

1976-01-01

Progress was made in the development of an RF cage, a single channel RF powered ECG telemetry system, and a three channel RF powered ECG, aortic blood pressure, and body temperature telemetry system. Encapsulation materials for chronic implantation of electronic circuits in the body were also evaluated.

Booster Synchrotron RF System Upgrade for SPEAR3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Sanghyun; /SLAC; Corbett, Jeff

2012-07-06

Recent progress at the SPEAR3 includes the increase in stored current from 100 mA to 200 mA and top-off injection to allow beamlines to stay open during injection. Presently the booster injects 3.0 GeV beam to SPEAR3 three times a day. The stored beam decays to about 150 mA between the injections. The growing user demands are to increase the stored current to the design value of 500 mA, and to maintain it at a constant value within a percent or so. To achieve this goal the booster must inject once every few minutes. For improved injection efficiency, all RFmore » systems at the linac, booster and SPEAR3 need to be phase-locked. The present booster RF system is basically a copy of the SPEAR2 RF system with 358.5 MHz and 40 kW peak RF power driving a 5-cell RF cavity for 1.0 MV gap voltage. These requirements entail a booster RF system upgrade to a scaled down version of the SPEAR3 RF system of 476.3 MHz with 1.2 MW cw klystron output power capabilities. We will analyze each subsystem option for their merits within budgetary and geometric space constraints. A substantial portion of the system will come from the decommissioned PEP-II RF stations.« less

Sb-Based Double Heterojunction Bipolar Transistors (DHBTs) With Fmax 650GHz for 340GHz Transmitter

DTIC Science & Technology

2008-12-01

PROPER IDENTIFICATION . NOT TO BE USED FOR INTERIM PROGRESS REPORTS SEE PAGE 2 FOR INTERIM PROGRESS REPORT INSTRUCTIONS MEMORANDUM OF TRANSMITTAL...conduction band lineup . These advantages have led to rapid progress in increasing device bandwidths, allowing competitive RF performance with established

Construction and Testing of Broadband High Impedance Ground Planes (HIGPS) for Surface Mount Antennas

DTIC Science & Technology

2008-03-01

Conductor PMC: Perfect Magnetic Conductor RF: Radio Frequency RH: Right-handed SNG : Single Negative TACAN: Tactical Air Navigation UAV: Unmanned Aerial...negative ( SNG ) and double-negative (DNG) materials, and their fascinating properties have driven the interest in MTMs (Engheta and Ziolkowski, 2006

An analog RF gap voltage regulation system for the Advanced Photon Source storage ring.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horan, D.

1999-04-13

An analog rf gap voltage regulation system has been designed and built at Argonne National Laboratory to maintain constant total storage ring rf gap voltage, independent of beam loading and cavity tuning effects. The design uses feedback control of the klystron mod-anode voltage to vary the amount of rf power fed to the storage ring cavities. The system consists of two independent feedback loops, each regulating the combined rf gap voltages of eight storage ring cavities by varying the output power of either one or two rf stations, depending on the mode of operation. It provides full operator control andmore » permissive logic to permit feedback control of the rf system output power only if proper conditions are met. The feedback system uses envelope-detected cavity field probe outputs as the feedback signal. Two different methods of combining the individual field probe signals were used to generate a relative DC level representing one-half of the total storage ring rf voltage, an envelope-detected vector sum of the field probe rf signals, and the DC sum of individual field probe envelope detector outputs. The merits of both methods are discussed. The klystron high-voltage power supply (HVPS) units are fitted with an analog interface for external control of the mod-anode voltage level, using a four-quadrant analog multiplier to modulate the HVPS mod-anode voltage regulator set-point in response to feedback system commands.« less

Active high-power RF switch and pulse compression system

DOEpatents

Tantawi, Sami G.; Ruth, Ronald D.; Zolotorev, Max

1998-01-01

A high-power RF switching device employs a semiconductor wafer positioned in the third port of a three-port RF device. A controllable source of directed energy, such as a suitable laser or electron beam, is aimed at the semiconductor material. When the source is turned on, the energy incident on the wafer induces an electron-hole plasma layer on the wafer, changing the wafer's dielectric constant, turning the third port into a termination for incident RF signals, and. causing all incident RF signals to be reflected from the surface of the wafer. The propagation constant of RF signals through port 3, therefore, can be changed by controlling the beam. By making the RF coupling to the third port as small as necessary, one can reduce the peak electric field on the unexcited silicon surface for any level of input power from port 1, thereby reducing risk of damaging the wafer by RF with high peak power. The switch is useful to the construction of an improved pulse compression system to boost the peak power of microwave tubes driving linear accelerators. In this application, the high-power RF switch is placed at the coupling iris between the charging waveguide and the resonant storage line of a pulse compression system. This optically controlled high power RF pulse compression system can handle hundreds of Megawatts of power at X-band.

The CEBAF RF Separator System Upgrade

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. Hovater; Mark Augustine; Al Guerra

2004-08-01

The CEBAF accelerator uses RF deflecting cavities operating at the third sub-harmonic (499 MHz) of the accelerating frequency (1497 MHz) to ''kick'' the electron beam to the experimental halls. The cavities operate in a TEM dipole mode incorporating mode enhancing rods to increase the cavity's transverse shunt impedance [1]. As the accelerators energy has increased from 4 GeV to 6 GeV the RF system, specifically the 1 kW solid-state amplifiers, have become problematic, operating in saturation because of the increased beam energy demands. Two years ago we began a study to look into replacement for the RF amplifiers and decidedmore » to use a commercial broadcast Inductive Output Tube (IOT) capable of 30 kW. The new RF system uses one IOT amplifier on multiple cavities as opposed to one amplifier per cavity as was originally used. In addition, the new RF system supports a proposed 12 GeV energy upgrade to CEBAF. We are currently halfway through the upgrade with three IOTs in operation and the remaining one nearly installed. This paper reports on the new RF system and the IOT performance.« less

Fast shut-down protection system for radio frequency breakdown and multipactor testing.

PubMed

Graves, T P; Hanson, P; Michaelson, J M; Farkas, A D; Hubble, A A

2014-02-01

Radio frequency (RF) breakdown such as multipactor or ionization breakdown is a device-limiting phenomenon for on-orbit spacecraft used for communication, navigation, or other RF payloads. Ground testing is therefore part of the qualification process for all high power components used in these space systems. This paper illustrates a shut-down protection system to be incorporated into multipactor/ionization breakdown ground testing for susceptible RF devices. This 8 channel system allows simultaneous use of different diagnostic classes and different noise floors. With initiation of a breakdown event, diagnostic signals increase above a user-specified level, which then opens an RF switch to eliminate RF power from the high power amplifier. Examples of this system in use are shown for a typical setup, illustrating the reproducibility of breakdown threshold voltages and the lack of multipactor conditioning. This system can also be utilized to prevent excessive damage to RF components in tests with sensitive or flight hardware.

Ion acceleration in a helicon source due to the self-bias effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiebold, Matt; Sung, Yung-Ta; Scharer, John E.

2012-05-15

Time-averaged plasma potential differences up to 165 V over several hundred Debye lengths are observed in low pressure (p{sub n} < 1 mTorr) expanding argon plasmas in the Madison Helicon eXperiment (MadHeX). The potential gradient leads to ion acceleration greater than that predicted by ambipolar expansion, exceeding E{sub i} Almost-Equal-To 7 kT{sub e} in some cases. RF power up to 500 W at 13.56 MHz is supplied to a half-turn, double-helix antenna in the presence of a nozzle magnetic field, adjustable up to 1 kG. A retarding potential analyzer (RPA) measures the ion energy distribution function (IEDF) and a sweptmore » emissive probe measures the plasma potential. Single and double probes measure the electron density and temperature. Two distinct mode hops, the capacitive-inductive (E-H) and inductive-helicon (H-W) transitions, are identified by jumps in density as RF power is increased. In the capacitive (E) mode, large fluctuations of the plasma potential (V{sub p-p} Greater-Than-Or-Equivalent-To 140V, V{sub p-p}/V{sub p} Almost-Equal-To 150%) exist at the RF frequency and its harmonics. The more mobile electrons can easily respond to RF-timescale gradients in the plasma potential whereas the inertially constrained ions cannot, leading to an initial flux imbalance and formation of a self-bias voltage between the source and expansion chambers. In the capacitive mode, the ion acceleration is not well described by an ambipolar relation, while in the inductive and helicon modes the ion acceleration more closely follows an ambipolar relation. The scaling of the potential gradient with the argon flow rate and RF power are investigated, with the largest potential gradients observed for the lowest flow rates in the capacitive mode. The magnitude of the self-bias voltage agrees with that predicted for RF self-bias at a wall. Rapid fluctuations in the plasma potential result in a time-dependent axial electron flux that acts to 'neutralize' the accelerated ion population, resulting in a zero net time-averaged current through the acceleration region when an insulating upstream boundary condition is enforced. Grounding the upstream endplate increases the self-bias voltage compared to a floating endplate.« less

Instrumentation and test methods of an automated radiated susceptibility system

NASA Astrophysics Data System (ADS)

Howard, M. W.; Deere, J.

1983-09-01

The instrumentation and test methods of an automated electromagnetic compatibility (EMC) system for performing radiated susceptibility tests from 14 kHz to 1000 MHz is described. Particular emphasis is given to the effectiveness of the system in the evaluation of electronic circuits for susceptibility to RF radiation. The system consists of a centralized data acquisition/control unit which interfaces with the equipment under test (EUT), the RF isolated field probes, and RF amplifier ALC output; four broadband linear RF amplifiers; and a frequency synthesizer with drive level increments in steps of 0.1 dB. Centralized control of the susceptibility test system is provided by a desktop computer. It is found that the system can reduce the execution time of RF susceptibility tests by as much as 70 percent. A block diagram of the system is provided.

Complementary clinical effects of topical tightening treatment in conjunction with a radiofrequency procedure.

PubMed

Goldberg, David J; Yatskayer, Margarita; Raab, Susana; Chen, Nannan; Krol, Yevgeniy; Oresajo, Christian

2014-10-01

Abstract Background: Skin laxity and cellulite on the buttocks and thighs are two common cosmetic concerns. Skin tightening with radiofrequency (RF) devices has become increasingly popular. The purpose of this study is to evaluate the efficacy and safety of a topical skin laxity tightening agent when used in combination with an RF device. A double-blinded, randomized clinical trial enrolled twenty females with mild-to-moderate skin laxity on the posterior thighs/buttocks. Each subject underwent two monthly treatments with an RF source (Alma Accent) to both legs. Subjects were then randomized to apply a topical agent (Skinceuticals Body Tightening Concentrate) twice daily to only one designated thigh/buttock throughout the eight-week duration of the study. All subjects were evaluated for improvement in lifting, skin tone, radiance, firmness/tightness, skin texture, and overall appearance based on photographic evaluation by blinded investigators at 12 weeks following the final RF treatment. A statistically significant improvement was found in the overall appearance on both sides treated with the RF device when compared to baseline. However, the area treated with the topical agent showed a statistically significantly greater degree of improvement than the side where no topical agent was applied. No adverse effects were reported. The use of a novel skin tightening agent used after RF procedures is both safe and effective for treatment of skin laxity on the buttocks and thighs. Combined therapy leads to a better result.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vorogushin, M.F.

Principle and experimental analysis of RF power feed system, based on 3 db directional couplers, for undesirable modes eliminating, divided power coupling with the RFQ accelerating structure, endotron type RF power source matching, are presented. The structure fine tuning and the system adjustment results and high-speed RF autocontrol system design are considered also.

A noncontact RF-based respiratory sensor: results of a clinical trial.

PubMed

Madsen, Spence; Baczuk, Jordan; Thorup, Kurt; Barton, Richard; Patwari, Neal; Langell, John T

2016-06-01

Respiratory rate (RR) is a critical vital signs monitored in health care setting. Current monitors suffer from sensor-contact failure, inaccurate data, and limited patient mobility. There is a critical need for an accurate and reliable and noncontact system to monitor RR. We developed a contact-free radio frequency (RF)-based system that measures movement using WiFi signal diffraction, which is converted into interpretable data using a Fourier transform. Here, we investigate the system's ability to measure fine movements associated with human respiration. Testing was conducted on subjects using visual cue, fixed-tempo instruction to breath at standard RRs. Blinded instruction-based RRs were compared to RF-acquired data to determine measurement accuracy. The RF-based technology was studied on postoperative ventilator-dependent patients. Blinded ventilator capnographic RR data were collected for each patient and compared to RF-acquired data to determine measurement accuracy. Respiratory rate data collected from 10 subjects breathing at a fixed RR (14, 16, 18, or 20) demonstrated 95.5% measurement accuracy between the patient's actual rate and that measured by our RF technology. Ten patients were enrolled into the clinical trial. Blinded ventilator capnographic RR data were compared to RF-based acquired data. The RF-based data showed 88.8% measurement accuracy with ventilator capnography. Initial clinical pilot trials with our contact-free RF-based monitoring system demonstrate a high degree of RR measurement accuracy when compared to capnographic data. Based on these results, we believe RF-based systems present a promising noninvasive, inexpensive, and accurate tool for continuous RR monitoring. Copyright © 2016 Elsevier Inc. All rights reserved.

Divergent fifteen-year trends in traditional and cardiometabolic risk factors of cardiovascular diseases in the Seychelles.

PubMed

Bovet, Pascal; Romain, Sarah; Shamlaye, Conrad; Mendis, Shanti; Darioli, Roger; Riesen, Walter; Tappy, Luc; Paccaud, Fred

2009-06-26

Few studies have assessed secular changes in the levels of cardiovascular risk factors (CV-RF) in populations of low or middle income countries. The systematic collection of a broad set of both traditional and metabolic CV-RF in 1989 and 2004 in the population of the Seychelles islands provides a unique opportunity to examine trends at a fairly early stage of the "diabesity" era in a country in the African region. Two examination surveys were conducted in independent random samples of the population aged 25-64 years in 1989 and 2004, attended by respectively 1081 and 1255 participants (participation rates >80%). All results are age-standardized to the WHO standard population. In 2004 vs. 1989, the levels of the main traditional CV-RF have either decreased, e.g. smoking (17% vs. 30%, p < 0.001), mean blood pressure (127.8/84.8 vs. 130.0/83.4 mmHg, p < 0.05), or only moderately increased, e.g. median LDL-cholesterol (3.58 vs. 3.36 mmol/l, p < 0. 01). In contrast, marked detrimental trends were found for obesity (37% vs. 21%, p < 0.001) and several cardiometabolic CVD-RF, e.g. mean HDL-cholesterol (1.36 vs. 1.40 mmol/l, p < 0.05), median triglycerides (0.80 vs. 0.78 mmol/l, p < 0.01), mean blood glucose (5.89 vs. 5.22 mmol/l, p < 0.001), median insulin (11.6 vs. 8.3 micromol/l, p < 0.001), median HOMA-IR (2.9 vs. 1.8, p < 0.001) and diabetes (9.4% vs. 6.2%, p < 0.001). At age 40-64, the prevalence of elevated total cardiovascular risk tended to decrease (e.g. WHO-ISH risk score > or =10; 11% vs. 13%, ns), whereas the prevalence of the metabolic syndrome (which integrates several cardiometabolic CVD-RF) nearly doubled (36% vs. 20%, p < 0.001). Data on physical activity and on intake of alcohol, fruit and vegetables are also provided. Awareness and treatment rates improved substantially for hypertension and diabetes, but control rates improved for the former only. Median levels of the cardiometabolic CVD-RF increased between 1989 and 2004 within all BMI strata, suggesting that the worsening levels of cardiometabolic CVD-RF in the population were not only related to increasing BMI levels in the interval. The levels of several traditional CVD-RF improved over time, while marked detrimental trends were observed for obesity, diabetes and several cardiometabolic factors. Thus, in this population, the rapid health transition was characterized by substantial changes in the patterns of CVD-RF. More generally, this analysis suggests the importance of surveillance systems to identify risk factor trends and the need for preventive strategies to promote healthy lifestyles and nutrition.

Impurity screening behavior of the high-field side scrape-off layer in near-double-null configurations: prospect for mitigating plasma-material interactions on RF actuators and first-wall components

NASA Astrophysics Data System (ADS)

LaBombard, B.; Kuang, A. Q.; Brunner, D.; Faust, I.; Mumgaard, R.; Reinke, M. L.; Terry, J. L.; Howard, N.; Hughes, J. W.; Chilenski, M.; Lin, Y.; Marmar, E.; Rice, J. E.; Rodriguez-Fernandez, P.; Wallace, G.; Whyte, D. G.; Wolfe, S.; Wukitch, S.

2017-07-01

The impurity screening response of the high-field side (HFS) scrape-off layer (SOL) to localized nitrogen injection is investigated on Alcator C-Mod for magnetic equilibria spanning lower-single-null, double-null and upper-single-null configurations under otherwise identical plasma conditions. L-mode, EDA H-mode and I-mode discharges are investigated. HFS impurity screening is found to depend on magnetic flux balance and the direction of B  ×  \

System integration of RF based negative ion experimental facility at IPR

NASA Astrophysics Data System (ADS)

Bansal, G.; Bandyopadhyay, M.; Singh, M. J.; Gahlaut, A.; Soni, J.; Pandya, K.; Parmar, K. G.; Sonara, J.; Chakraborty, A.

2010-02-01

The setting up of RF based negative ion experimental facility shall witness the beginning of experiments on the negative ion source fusion applications in India. A 1 MHz RF generator shall launch 100 kW RF power into a single driver on the plasma source to produce a plasma of density ~5 × 1012 cm-3. The source can deliver a negative ion beam of ~10 A with a current density of ~30 mA/cm2 and accelerated to 35 kV through an electrostatic ion accelerator. The experimental system is similar to a RF based negative ion source, BATMAN, presently operating at IPP. The subsystems for source operation are designed and procured principally from indigenous resources, keeping the IPP configuration as a base line. The operation of negative ion source is supported by many subsystems e.g. vacuum pumping system with gate valves, cooling water system, gas feed system, cesium delivery system, RF generator, high voltage power supplies, data acquisition and control system, and different diagnostics. The first experiments of negative ion source are expected to start at IPR from the middle of 2009.

Direct coupling of pulsed radio frequency and pulsed high power in novel pulsed power system for plasma immersion ion implantation.

PubMed

Gong, Chunzhi; Tian, Xiubo; Yang, Shiqin; Fu, Ricky K Y; Chu, Paul K

2008-04-01

A novel power supply system that directly couples pulsed high voltage (HV) pulses and pulsed 13.56 MHz radio frequency (rf) has been developed for plasma processes. In this system, the sample holder is connected to both the rf generator and HV modulator. The coupling circuit in the hybrid system is composed of individual matching units, low pass filters, and voltage clamping units. This ensures the safe operation of the rf system even when the HV is on. The PSPICE software is utilized to optimize the design of circuits. The system can be operated in two modes. The pulsed rf discharge may serve as either the seed plasma source for glow discharge or high-density plasma source for plasma immersion ion implantation (PIII). The pulsed high-voltage glow discharge is induced when a rf pulse with a short duration or a larger time interval between the rf and HV pulses is used. Conventional PIII can also be achieved. Experiments conducted on the new system confirm steady and safe operation.

Commissioning and Early Operation Experience of the NSLS-II Storage Ring RF System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, F.; Rose, J.; Cupolo, J.

2015-05-03

The National Synchrotron Light Source II (NSLS-II) is a 3 GeV electron X-ray user facility commissioned in 2014. The storage ring RF system, essential for replenishing energy loss per turn of the electrons, consists of digital low level RF controllers, 310 kW CW klystron transmitters, CESR-B type superconducting cavities, as well as a supporting cryogenic system. Here we will report on RF commissioning and early operation experience of the system for beam current up to 200mA.

FERMILAB CRYOMODULE TEST STAND RF INTERLOCK SYSTEM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Petersen, Troy; Diamond, J. S.; McDowell, D.

2016-10-12

An interlock system has been designed for the Fermilab Cryo-module Test Stand (CMTS), a test bed for the cryo- modules to be used in the upcoming Linac Coherent Light Source 2 (LCLS-II) project at SLAC. The interlock system features 8 independent subsystems, one per superconducting RF cavity and solid state amplifier (SSA) pair. Each system monitors several devices to detect fault conditions such as arcing in the waveguides or quenching of the SRF system. Additionally each system can detect fault conditions by monitoring the RF power seen at the cavity coupler through a directional coupler. In the event of amore » fault condition, each system is capable of removing RF signal to the amplifier (via a fast RF switch) as well as turning off the SSA. Additionally, each input signal is available for re- mote viewing and recording via a Fermilab designed digitizer board and MVME 5500 processor.« less

History and Technology Developments of Radio Frequency (RF) Systems for Particle Accelerators

NASA Astrophysics Data System (ADS)

Nassiri, A.; Chase, B.; Craievich, P.; Fabris, A.; Frischholz, H.; Jacob, J.; Jensen, E.; Jensen, M.; Kustom, R.; Pasquinelli, R.

2016-04-01

This article attempts to give a historical account and review of technological developments and innovations in radio frequency (RF) systems for particle accelerators. The evolution from electrostatic field to the use of RF voltage suggested by R. Wideröe made it possible to overcome the shortcomings of electrostatic accelerators, which limited the maximum achievable electric field due to voltage breakdown. After an introduction, we will provide reviews of technological developments of RF systems for particle accelerators.

HIMAC RF system with a digital synthesizer

NASA Astrophysics Data System (ADS)

Kanazawa, M.; Sato, K.; Itano, A.; Sudou, M.; Noda, K.; Takada, E.; Kumada, M.; Yamazaki, C.; Yamagishi, T.; Morii, Y.; Toyoda, E.; Tsuzuki, N.; Yagi, T.

2000-04-01

An RF acceleration system, in which digital control with a direct digital synthesizer (DDS) is applied, has been developed for the Heavy Ion Medical Accelerator in Chiba (HIMAC) synchrotron. This digital system allows us to obtain stable operation of the acceleration system over a wide frequency range from 1.04 to 7.9 MHz. In this paper the designed digital RF control system and its performance are described.

Slip-stacking Dynamics for High-Power Proton Beams at Fermilab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldred, Jeffrey Scott

Slip-stacking is a particle accelerator configuration used to store two particle beams with different momenta in the same ring. The two beams are longitudinally focused by two radiofrequency (RF) cavities with a small frequency difference between them. Each beam is synchronized to one RF cavity and perturbed by the other RF cavity. Fermilab uses slip-stacking in the Recycler so as to double the power of the 120 GeV proton beam in the Main Injector. This dissertation investigates the dynamics of slip-stacking beams analytically, numerically and experimentally. In the analytic analysis, I find the general trajectory of stable slip-stacking particles andmore » identify the slip-stacking parametric resonances. In the numerical analysis, I characterize the stable phase-space area and model the particle losses. In particular, I evaluate the impact of upgrading the Fermilab Booster cycle-rate from 15 Hz to 20 Hz as part of the Proton Improvement Plan II (PIP-II). The experimental analysis is used to verify my approach to simulating slip-stacking loss. I design a study for measuring losses from the longitudinal single-particle dynamics of slip-stacking as a function of RF cavity voltage and RF frequency separation. I further propose the installation of a harmonic RF cavity and study the dynamics of this novel slip-stacking configuration. I show the harmonic RF cavity cancels out parametric resonances in slip-stacking, reduces emittance growth during slip-stacking, and dramatically enhances the stable phase-space area. The harmonic cavity is expected to reduce slip-stacking losses to far exceed PIP-II requirements. These results raise the possibility of extending slip-stacking beyond the PIP-II era.« less

Radiofrequency electromagnetic field exposure and non-specific symptoms of ill health: a systematic review.

PubMed

Röösli, Martin

2008-06-01

This article is a systematic review of whether everyday exposure to radiofrequency electromagnetic field (RF-EMF) causes symptoms, and whether some individuals are able to detect low-level RF-EMF (below the ICNIRP [International Commission on Non-Ionizing Radiation Protection] guidelines). Peer-reviewed articles published before August 2007 were identified by means of a systematic literature search. Meta-analytic techniques were used to pool the results from studies investigating the ability to discriminate active from sham RF-EMF exposure. RF-EMF discrimination was investigated in seven studies including a total of 182 self-declared electromagnetic hypersensitive (EHS) individuals and 332 non-EHS individuals. The pooled correct field detection rate was 4.2% better than expected by chance (95% CI: -2.1 to 10.5). There was no evidence that EHS individuals could detect presence or absence of RF-EMF better than other persons. There was little evidence that short-term exposure to a mobile phone or base station causes symptoms based on the results of eight randomized trials investigating 194 EHS and 346 non-EHS individuals in a laboratory. Some of the trials provided evidence for the occurrence of nocebo effects. In population based studies an association between symptoms and exposure to RF-EMF in the everyday environment was repeatedly observed. This review showed that the large majority of individuals who claims to be able to detect low level RF-EMF are not able to do so under double-blind conditions. If such individuals exist, they represent a small minority and have not been identified yet. The available observational studies do not allow differentiating between biophysical from EMF and nocebo effects.

Radiofrequency electromagnetic field exposure and non-specific symptoms of ill health: A systematic review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roeoesli, Martin

2008-06-15

This article is a systematic review of whether everyday exposure to radiofrequency electromagnetic field (RF-EMF) causes symptoms, and whether some individuals are able to detect low-level RF-EMF (below the ICNIRP [International Commission on Non-Ionizing Radiation Protection] guidelines). Peer-reviewed articles published before August 2007 were identified by means of a systematic literature search. Meta-analytic techniques were used to pool the results from studies investigating the ability to discriminate active from sham RF-EMF exposure. RF-EMF discrimination was investigated in seven studies including a total of 182 self-declared electromagnetic hypersensitive (EHS) individuals and 332 non-EHS individuals. The pooled correct field detection rate wasmore » 4.2% better than expected by chance (95% CI: -2.1 to 10.5). There was no evidence that EHS individuals could detect presence or absence of RF-EMF better than other persons. There was little evidence that short-term exposure to a mobile phone or base station causes symptoms based on the results of eight randomized trials investigating 194 EHS and 346 non-EHS individuals in a laboratory. Some of the trials provided evidence for the occurrence of nocebo effects. In population based studies an association between symptoms and exposure to RF-EMF in the everyday environment was repeatedly observed. This review showed that the large majority of individuals who claims to be able to detect low level RF-EMF are not able to do so under double-blind conditions. If such individuals exist, they represent a small minority and have not been identified yet. The available observational studies do not allow differentiating between biophysical from EMF and nocebo effects.« less

Terminal field specificity of forebrain efferent axons to the pontine parabrachial nucleus and medullary reticular formation

PubMed Central

Zhang, Chi; Kang, Yi; Lundy, Robert F.

2010-01-01

The pontine parabrachial nucleus (PBN) and medullary reticular formation (RF) are hindbrain regions that, respectively, process sensory input and coordinate motor output related to ingestive behavior. Neural processing in each hindbrain site is subject to modulation originating from several forebrain structures including the insular gustatory cortex (IC), bed nucleus of the stria terminalis (BNST), central nucleus of the amygdala (CeA), and lateral hypothalamus (LH). The present study combined electrophysiology and retrograde tracing techniques to determine the extent of overlap between neurons within the IC, BNST, CeA and LH that target both the PBN and RF. One fluorescent retrograde tracer, red (RFB) or green (GFB) latex microbeads, was injected into the gustatory PBN under electrophysiological guidance and a different retrograde tracer, GFB or fluorogold (FG), into the ipsilateral RF using the location of gustatory NST as a point of reference. Brain tissue containing each forebrain region was sectioned, scanned using a confocal microscope, and scored for the number of single and double labeled neurons. Neurons innervating the RF only, the PBN only, or both the medullary RF and PBN were observed, largely intermingled, in each forebrain region. The CeA contained the largest number of cells retrogradely labeled after tracer injection into either hindbrain region. For each forebrain area except the IC, the origin of descending input to the RF and PBN was almost entirely ipsilateral. Axons from a small percentage of hindbrain projecting forebrain neurons targeted both the PBN and RF. Target specific and non specific inputs from a variety of forebrain nuclei to the hindbrain likely reflect functional specialization in the control of ingestive behaviors. PMID:21040715

Repetitively Pulsed High Power RF Solid-State System

NASA Astrophysics Data System (ADS)

Bowman, Chris; Ziemba, Timothy; Miller, Kenneth E.; Prager, James; Quinley, Morgan

2017-10-01

Eagle Harbor Technologies, Inc. (EHT) is developing a low-cost, fully solid-state architecture for the generation of the RF frequencies and power levels necessary for plasma heating and diagnostic systems at validation platform experiments within the fusion science community. In Year 1 of this program, EHT has developed a solid-state RF system that combines an inductive adder, nonlinear transmission line (NLTL), and antenna into a single system that can be deployed at fusion science experiments. EHT has designed and optimized a lumped-element NLTL that will be suitable RF generation near the lower-hybrid frequency at the High Beta Tokamak (HBT) located at Columbia University. In Year 2, EHT will test this system at the Helicity Injected Torus at the University of Washington and HBT at Columbia. EHT will present results from Year 1 testing and optimization of the NLTL-based RF system. With support of DOE SBIR.

Fabrication and analysis of radiofrequency MEMS series capacitive single-pole double-throw switch

NASA Astrophysics Data System (ADS)

Bansal, Deepak; Bajpai, Anuroop; Kumar, Prem; Kaur, Maninder; Rangra, Kamaljit

2016-10-01

A compact radiofrequency (RF) MEMS single-pole double-throw (SPDT) switch based on series capacitive configuration is proposed. The critical process parameters are analyzed to improve the fabrication process. A technique of cold-hot thermal shock for lift-off method is explored. The residual stress in the structure is quantified by lancet test structures that come out to be 51 MPa. Effect of residual stress on actuation voltage is explored, which changes its value from 24 to 22 V. Resonance frequency and switching speed of the switch are 11 kHz and 44 μs, respectively, measured using laser Doppler vibrometer. Measured bandwidth of the SPDT switch is 20 GHz (5 to 25 GHz), which is verified with finite element method simulations in high frequency structure simulator©; and an equivalent LCR circuit in advanced design system©;. Insertion loss of the switch lies in -0.1 to -0.5 dB with isolation better than -20 dB for the above-mentioned bandwidth.

Electron bunch energy and phase feed-forward stabilization system for the Mark V RF-linac free-electron laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadmack, M. R.; Kowalczyk, J. M. D.; Lienert, B. R.

2013-06-15

An amplitude and phase compensation system has been developed and tested at the University of Hawai'i for the optimization of the RF drive system to the Mark V free-electron laser. Temporal uniformity of the RF drive is essential to the generation of an electron beam suitable for optimal free-electron laser performance and the operation of an inverse Compton scattering x-ray source. The design of the RF measurement and compensation system is described in detail and the results of RF phase compensation are presented. Performance of the free-electron laser was evaluated by comparing the measured effects of phase compensation with themore » results of a computer simulation. Finally, preliminary results are presented for the effects of amplitude compensation on the performance of the complete system.« less

SalB inactivation modulates culture supernatant exoproteins and affects autolysis and viability in Enterococcus faecalis OG1RF.

PubMed

Shankar, Jayendra; Walker, Rachel G; Wilkinson, Mark C; Ward, Deborah; Horsburgh, Malcolm J

2012-07-01

The culture supernatant fraction of an Enterococcus faecalis gelE mutant of strain OG1RF contained elevated levels of the secreted antigen SalB. Using differential fluorescence gel electrophoresis (DIGE) the salB mutant was shown to possess a unique complement of exoproteins. Differentially abundant exoproteins were identified using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Stress-related proteins including DnaK, Dps family protein, SOD, and NADH peroxidase were present in greater quantity in the OG1RF salB mutant culture supernatant. Moreover, several proteins involved in cell wall synthesis and cell division, including d-Ala-d-Lac ligase and EzrA, were present in reduced quantity in OG1RF salB relative to the parent strain. The salB mutant displayed reduced viability and anomalous cell division, and these phenotypes were exacerbated in a gelE salB double mutant. An epistatic relationship between gelE and salB was not identified with respect to increased autolysis and cell morphological changes observed in the salB mutant. SalB was purified as a six-histidine-tagged protein to investigate peptidoglycan hydrolytic activity; however, activity was not evident. High-pressure liquid chromatography (HPLC) analysis of reduced muropeptides from peptidoglycan digested with mutanolysin revealed that the salB mutant and OG1RF were indistinguishable.

Development of a dual-pulse RF driver for an S-band (= 2856 MHz) RF electron linear accelerator

NASA Astrophysics Data System (ADS)

Cha, Sungsu; Kim, Yujong; Lee, Byeong-No; Lee, Byung Cheol; Cha, Hyungki; Ha, Jang Ho; Park, Hyung Dal; Lee, Seung Hyun; Kim, Hui Su; Buaphad, Pikad

2016-04-01

The radiation equipment research division of Korea Atomic Energy Research Institute has developed a Container Inspection System (CIS) using a Radio Frequency (RF) electron linear accelerator for port security. The primary purpose of the CIS is to detect nuclear materials and explosives, as well country-specific prohibited substances, e.g., smuggled. The CIS consists of a 9/6 MeV dualenergy electron linear accelerator for distinguishing between organic and inorganic materials. The accelerator consists of an electron gun, an RF accelerating structure, an RF driver, a modulator, electromagnets, a cooling system, a X-ray generating target, X-ray collimator, a detector, and a container moving system. The RF driver is an important part of the configuration because it is the RF power source: it supplies the RF power to the accelerating structure. A unique aspect of the RF driver is that it generates dual RF power to generate dual energy (9/6 MeV). The advantage of this RF driver is that it can allow the pulse width to vary and can be used to obtain a wide range of energy output, and pulse repetition rates up to 300 Hz. For this reason, 140 W (5 MW - 9 MeV) and 37 W (3.4 MW - 6 MeV) power outputs are available independently. A high power test for 20 minutes demonstrate that stable dual output powers can be generated. Moreover, the dual power can be applied to the accelerator which has stable accelerator operation. In this paper, the design, fabrication and high power test of the RF driver for the RF electron linear accelerator (linac) are presented.

Synthesis of ultrafine Si3N4 powder in RF-RF plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, Michitaka; Nishio, Hiroaki

1991-10-01

A newly designed plasma-CVD apparatus mounted with the RF-RF type plasma torch was introduced to synthesize ultrafine powders of silicon nitride (Si3N4). The RF-RF plasma system (the combination of a main (lower) and controlling (upper) RF plasma) improved the stability of simple RF plasma and solved the impurity problem of dc-RF hybrid plasma. The reaction of SiCl4 and NH3, which were radially injected into the tail flames of the upper and lower plasmas, respectively, yielded near-stoichiometric amorphous powders of Si3N4. The nitrogen content in the products largely depended on the flow rate of the quenching gas, a mixture of NH3more » (reactant) and H2. The oxygen content and metal impurities are 2-3 wt pct and less than 200 ppm, respectively. The powder particles had an average diameter of about 15 nm with a narrow size distribution, and showed extreme air sensitivity. Conspicuous crystallazation and particle growth occurred when heated at temperatures above 1400 C. These results suggested that the RF-RF system was a potential reactor for the synthesis of ultrafine powders with excellent sinterability at relatively low temperatures. 9 refs.« less

Comparison of radiofrequency body coils for MRI at 3 Tesla: a simulation study using parallel transmission on various anatomical targets

PubMed Central

Wu, Xiaoping; Zhang, Xiaotong; Tian, Jinfeng; Schmitter, Sebastian; Hanna, Brian; Strupp, John; Pfeuffer, Josef; Hamm, Michael; Wang, Dingxin; Nistler, Juergen; He, Bin; Vaughan, J. Thomas; Ugurbil, Kamil; Van de Moortele, Pierre-Francois

2015-01-01

The performance of multichannel transmit coil layouts and parallel transmission (pTx) radiofrequency (RF) pulse design was evaluated with respect to transmit B1 (B1+) homogeneity and Specific Absorption Rate (SAR) at 3 Tesla for a whole body coil. Five specific coils were modeled and compared: a 32-rung birdcage body coil (driven either in a fixed quadrature mode or a two-channel transmit mode), two single-ring stripline arrays (with either 8 or 16 elements), and two multi-ring stripline arrays (with 2 or 3 identical rings, stacked in the z-axis and each comprising eight azimuthally distributed elements). Three anatomical targets were considered, each defined by a 3D volume representative of a meaningful region of interest (ROI) in routine clinical applications. For a given anatomical target, global or local SAR controlled pTx pulses were designed to homogenize RF excitation within the ROI. At the B1+ homogeneity achieved by the quadrature driven birdcage design, pTx pulses with multichannel transmit coils achieved up to ~8 fold reduction in local and global SAR. When used for imaging head and cervical spine or imaging thoracic spine, the double-ring array outperformed all coils including the single-ring arrays. While the advantage of the double-ring array became much less pronounced for pelvic imaging with a substantially larger ROI, the pTx approach still provided significant gains over the quadrature birdcage coil. For all design scenarios, using the 3-ring array did not necessarily improve the RF performance. Our results suggest that pTx pulses with multichannel transmit coils can reduce local and global SAR substantially for body coils while attaining improved B1+ homogeneity, particularly for a “z-stacked” double-ring design with coil elements arranged on two transaxial rings. PMID:26332290

10 GHz dual loop opto-electronic oscillator without RF-amplifiers

NASA Astrophysics Data System (ADS)

Zhou, Weimin; Okusaga, Olukayode; Nelson, Craig; Howe, David; Carter, Gary

2008-02-01

We report the first demonstration of a 10 GHz dual-fiber-loop Opto-Electronic Oscillator (OEO) without RF-amplifiers. Using a recently developed highly efficient RF-Photonic link with RF-to-RF gain facilitated by a high power laser, highly efficient optical modulator and high power phototectectors, we have built an amplifier-less OEO that eliminates the phase noise produced by the electronic amplifier. The dual-loop approach can provide additional gain and reduce unwanted multi-mode spurs. However, we have observed RF phase noise produced by the high power laser include relative intensity noise (RIN) and noise related to the laser's electronic control system. In addition, stimulated Brillouin scattering limits the fiber loop's length to ~2km at the 40mW laser power needed to provide the RF gain which limits the system's quality factor, Q. We have investigated several different methods for solving these problems. One promising technique is the use of a multi-longitudinal-mode laser to carry the RF signal, maintaining the total optical power but reducing the optical power of each mode to eliminate the Brillouin scattering in a longer fiber thereby reducing the phase noise of the RF signal produced by the OEO. This work shows that improvement in photonic components increases the potential for more RF system applications such as an OEO's with higher performance and new capabilities.

RF control at SSCL — an object oriented design approach

NASA Astrophysics Data System (ADS)

Dohan, D. A.; Osberg, E.; Biggs, R.; Bossom, J.; Chillara, K.; Richter, R.; Wade, D.

1994-12-01

The Superconducting Super Collider (SSC) in Texas, the construction of which was stopped in 1994, would have represented a major challenge in accelerator research and development. This paper addresses the issues encountered in the parallel design and construction of the control systems for the RF equipment for the five accelerators comprising the SSC. An extensive analysis of the components of the RF control systems has been undertaken, based upon the Schlaer-Mellor object-oriented analysis and design (OOA/OOD) methodology. The RF subsystem components such as amplifiers, tubes, power supplies, PID loops, etc. were analyzed to produce OOA information, behavior and process models. Using these models, OOD was iteratively applied to develop a generic RF control system design. This paper describes the results of this analysis and the development of 'bridges' between the analysis objects, and the EPICS-based software and underlying VME-based hardware architectures. The application of this approach to several of the SSCL RF control systems is discussed.

Unloading-induced slow-to-fast myosin shift in soleus muscle: nuclear MuRFs and calsarcin expression

NASA Astrophysics Data System (ADS)

Shenkman, Boris; Lomonosova, Yulia

Exposure to actual and simulated microgravity is known to induce decrease in slow MyHC mRNA expression and increase in fast MyHC mRNAs expression. We supposed that altered expression of the calsarcin (CS) I and II (specific for type I and type II fibers respectively) may provide the control over myosin phenotype during unloading. We found that after 3 days of hindlimb unloading (HU) the content of CSII mRNA increased two-fold in rat soleus as compared to the cage controls. This level was maintained till the 7th day of the exposure and increased by more than 5-fold (as compared to controls) after two weeks of HU. In contrast to CSII, CSI mRNA expression didn’t change after 3 days of HU, but decreased more than 2-fold by the 7th and 14th day of HU. The increase of CSII RNA (in type II fibers) may be explained as the mechanism of stabilization of fast phenotype in all, but more important, in newly transformed type II fibers. At the same time, the decrease of CSI mRNA (in type I fibers) may be understood as counteracting the slow-to-fast transformation. Morriscot et al, (2010) demonstrated that calsarcin II expression decreased only in the double knockouts MuRF1-/MuRF2-. So, we hypothesized that CSII expression in unloaded soleus muscle might be associated with the cytoplasm-nucleus translocation of MuRF1 and MuRF2. We observed significant accumulation of MuRF1 and MuRF2 in the nuclear fraction after 3 days of HU. Thus the accumulation of MuRFs in myonuclei may promote the expression of CSII, necessary for stabilization of fast phenotype in the course of slow-to-fast shift in unloaded soleus muscle. We express our gratitude to Prof. S. Labeit (Mannheim) for kind presenting us the best antibodies against MuRF1 and MuRF2.

Screening and identification of gastric adenocarcinoma metastasis-related genes by using cDNA microarray coupled to FDD-PCR.

PubMed

Wang, Jian-Hua; Chen, Shi-Shu

2002-07-01

To clone gastric adenocarcinoma metastasis related genes, RF-1 cell line (primary tumor of a gastric adenocarcinoma patient ) and RF-48 cell line (its metastatic counterpart) were used as a model for studying the molecular mechanism of tumor metastasis. Two fluorescent cDNA probes, labeled with Cy3 and Cy5 dyes, were prepared from RF-1 and RF-48 mRNA samples by reverse transcription method. The two color probes were then mixed and hybridized to the cDNA chip constructed by double-dots of 4 096 human genes, and scanned at two wavelengths. The experiment was repeated for 2 times. Differential expression genes from the above two cells were analyzed using the computer. 138 in all genes (3.4%) revealed differential expression in RF-48 cells compared with RF-1 cells: 81(2.1%) genes revealed apparent up-regulation, and 56(1.3%) genes revealed down-regulation. 45 genes involved in gastric adenocarcinoma metastasis were cloned using fluorescent differential display-PCR (FDD-PCR), including 3 novel genes. There were 7 differential expression genes that agreed with each other in two detection methods. The possible roles of some differential expressed genes, which maybe involved in the mechanism of tumor metastasis, were discussed. cDNA chip was used to analyze gene expression in a high-throughput and large scale manner, in combination with FDD-PCR for cloning unknown novel genes. In conclusion, some genes related to metastasis were preliminarily scanned, which would contribute to disclose the molecular mechanism of gastric adenocarcinoma metastasis.

rf improvements for Spallation Neutron Source H- ion sourcea)

NASA Astrophysics Data System (ADS)

Kang, Y. W.; Fuja, R.; Goulding, R. H.; Hardek, T.; Lee, S.-W.; McCarthy, M. P.; Piller, M. C.; Shin, K.; Stockli, M. P.; Welton, R. F.

2010-02-01

The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering ˜38 mA H- beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier.

rf improvements for Spallation Neutron Source H- ion source.

PubMed

Kang, Y W; Fuja, R; Goulding, R H; Hardek, T; Lee, S-W; McCarthy, M P; Piller, M C; Shin, K; Stockli, M P; Welton, R F

2010-02-01

The Spallation Neutron Source at Oak Ridge National Laboratory is ramping up the accelerated proton beam power to 1.4 MW and just reached 1 MW. The rf-driven multicusp ion source that originates from the Lawrence Berkeley National Laboratory has been delivering approximately 38 mA H(-) beam in the linac at 60 Hz, 0.9 ms. To improve availability, a rf-driven external antenna multicusp ion source with a water-cooled ceramic aluminum nitride (AlN) plasma chamber is developed. Computer modeling and simulations have been made to analyze and optimize the rf performance of the new ion source. Operational statistics and test runs with up to 56 mA medium energy beam transport beam current identify the 2 MHz rf system as a limiting factor in the system availability and beam production. Plasma ignition system is under development by using a separate 13 MHz system. To improve the availability of the rf power system with easier maintenance, we tested a 70 kV isolation transformer for the 80 kW, 6% duty cycle 2 MHz amplifier to power the ion source from a grounded solid-state amplifier.

Double-quantum homonuclear rotary resonance: Efficient dipolar recovery in magic-angle spinning nuclear magnetic resonance

NASA Astrophysics Data System (ADS)

Nielsen, N. C.; Bildsøe, H.; Jakobsen, H. J.; Levitt, M. H.

1994-08-01

We describe an efficient method for the recovery of homonuclear dipole-dipole interactions in magic-angle spinning NMR. Double-quantum homonuclear rotary resonance (2Q-HORROR) is established by fulfilling the condition ωr=2ω1, where ωr is the sample rotation frequency and ω1 is the nutation frequency around an applied resonant radio frequency (rf) field. This resonance can be used for double-quantum filtering and measurement of homonuclear dipolar interactions in the presence of magic-angle spinning. The spin dynamics depend only weakly on crystallite orientation allowing good performance for powder samples. Chemical shift effects are suppressed to zeroth order. The method is demonstrated for singly and doubly 13C labeled L-alanine.

Experimental observation of standing wave effect in low-pressure very-high-frequency capacitive discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yong-Xin; Gao, Fei; Liu, Jia

2014-07-28

Radial uniformity measurements of plasma density were carried out by using a floating double probe in a cylindrical (21 cm in electrode diameter) capacitive discharge reactor driven over a wide range of frequencies (27–220 MHz). At low rf power, a multiple-node structure of standing wave effect was observed at 130 MHz. The secondary density peak caused by the standing wave effect became pronounced and shifts toward the axis as the driving frequency further to increase, indicative of a much more shortened standing-wave wavelength. With increasing rf power, the secondary density peak shift toward the radial edge, namely, the standing-wave wavelength was increased,more » in good qualitative agreement with the previous theory and simulation results. At higher pressures and high frequencies, the rf power was primarily deposited at the periphery of the electrode, due to the fact that the waves were strongly damped as they propagated from the discharge edge into the center.« less

Superconducting terahertz mixer using a transition-edge microbolometer

NASA Technical Reports Server (NTRS)

Prober, D. E.

1993-01-01

We present a new device concept for a mixer element for THz frequencies. This uses a superconducting transition-edge microbridge biased at the center of its superconducting transition near 4.2 K. It is fed from an antenna or waveguide structure. Power from a local oscillator and an RF signal produce a temperature and resulting resistance variation at the difference frequency. The new aspect is the use of a very short bridge in which rapid (less than 0.1 ns) outdiffusion of hot electrons occurs. This gives large intermediate frequency (IF) response. The mixer offers about 4 GHz IF bandwidth, about 80 ohm RF resistive impedance, good match to the IF amplifier, and requires only 1-20 nW of local oscillator power. The upper RF frequency is determined by antenna or waveguide properties. Predicted mixer conversion efficiency is 1/8, and predicted double-sideband receiver noise temperatures are 260 and 90 K for transition widths of 0.1 and 0.5 Tc, respectively.

Analog Techniques in CEBAF's RF Control System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovater, J.; Fugitt, Jock

1988-01-01

Recent developments in high-speed analog technology have progressed into the areas of traditional RF technology.Diode-related devices are being replaced by analog IC's in the CEBAF RF control system.Complex phase modulators and attenuators have been successfully tested at 70 MHz.They have three advantages over existing technology: lower cost, less temperature sensitivity, and more linearity.RF signal conditioning components and how to implement the new analog IC's will be covered in this paper.

rf design of a pulse compressor with correction cavity chain for klystron-based compact linear collider

NASA Astrophysics Data System (ADS)

Wang, Ping; Zha, Hao; Syratchev, Igor; Shi, Jiaru; Chen, Huaibi

2017-11-01

We present an X-band high-power pulse compression system for a klystron-based compact linear collider. In this system design, one rf power unit comprises two klystrons, a correction cavity chain, and two SLAC Energy Doubler (SLED)-type X-band pulse compressors (SLEDX). An rf pulse passes the correction cavity chain, by which the pulse shape is modified. The rf pulse is then equally split into two ways, each deploying a SLEDX to compress the rf power. Each SLEDX produces a short pulse with a length of 244 ns and a peak power of 217 MW to power four accelerating structures. With the help of phase-to-amplitude modulation, the pulse has a dedicated shape to compensate for the beam loading effect in accelerating structures. The layout of this system and the rf design and parameters of the new pulse compressor are described in this work.

Integrated Inductors for RF Transmitters in CMOS/MEMS Smart Microsensor Systems

PubMed Central

Kim, Jong-Wan; Takao, Hidekuni; Sawada, Kazuaki; Ishida, Makoto

2007-01-01

This paper presents the integration of an inductor by complementary metal-oxide-semiconductor (CMOS) compatible processes for integrated smart microsensor systems that have been developed to monitor the motion and vital signs of humans in various environments. Integration of radio frequency transmitter (RF) technology with complementary metal-oxide-semiconductor/micro electro mechanical systems (CMOS/MEMS) microsensors is required to realize the wireless smart microsensors system. The essential RF components such as a voltage controlled RF-CMOS oscillator (VCO), spiral inductors for an LC resonator and an integrated antenna have been fabricated and evaluated experimentally. The fabricated RF transmitter and integrated antenna were packaged with subminiature series A (SMA) connectors, respectively. For the impedance (50 Ω) matching, a bonding wire type inductor was developed. In this paper, the design and fabrication of the bonding wire inductor for impedance matching is described. Integrated techniques for the RF transmitter by CMOS compatible processes have been successfully developed. After matching by inserting the bonding wire inductor between the on-chip integrated antenna and the VCO output, the measured emission power at distance of 5 m from RF transmitter was -37 dBm (0.2 μW).

RF/optical shared aperture for high availability wideband communication RF/FSO links

DOEpatents

Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

2014-04-29

An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

RF/optical shared aperture for high availability wideband communication RF/FSO links

DOEpatents

Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

2015-03-24

An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

Single frequency RF powered ECG telemetry system

NASA Technical Reports Server (NTRS)

Ko, W. H.; Hynecek, J.; Homa, J.

1979-01-01

It has been demonstrated that a radio frequency magnetic field can be used to power implanted electronic circuitry for short range telemetry to replace batteries. A substantial reduction in implanted volume can be achieved by using only one RF tank circuit for receiving the RF power and transmitting the telemetered information. A single channel telemetry system of this type, using time sharing techniques, was developed and employed to transmit the ECG signal from Rhesus monkeys in primate chairs. The signal from the implant is received during the period when the RF powering radiation is interrupted. The ECG signal is carried by 20-microsec pulse position modulated pulses, referred to the trailing edge of the RF powering pulse. Satisfactory results have been obtained with this single frequency system. The concept and the design presented may be useful for short-range long-term implant telemetry systems.

Increasing Gas Hydrate Formation Temperature for Desalination of High Salinity Produced Water with Secondary Guests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cha, Jong-Ho; Seol, Yongkoo

We suggest a new gas hydrate-based desalination process using water-immiscible hydrate formers; cyclopentane (CP) and cyclohexane (CH) as secondary hydrate guests to alleviate temperature requirements for hydrate formation. The hydrate formation reactions were carried out in an isobaric condition of 3.1 MPa to find the upper temperature limit of CO2 hydrate formation. Simulated produced water (8.95 wt % salinity) mixed with the hydrate formers shows an increased upper temperature limit from -2 °C for simple CO2 hydrate to 16 and 7 °C for double (CO2 + CP) and (CO2 + CH) hydrates, respectively. The resulting conversion rate to double hydratemore » turned out to be similar to that with simple CO2 hydrate at the upper temperature limit. Hydrate formation rates (Rf) for the double hydrates with CP and CH are shown to be 22 and 16 times higher, respectively, than that of the simple CO2 hydrate at the upper temperature limit. Such mild hydrate formation temperature and fast formation kinetics indicate increased energy efficiency of the double hydrate system for the desalination process. Dissociated water from the hydrates shows greater than 90% salt removal efficiency for the hydrates with the secondary guests, which is also improved from about 70% salt removal efficiency for the simple hydrates.« less

A 20fs synchronization system for lasers and cavities in accelerators and FELs

NASA Astrophysics Data System (ADS)

Wilcox, R. B.; Byrd, J. M.; Doolittle, L. R.; Huang, G.; Staples, J. W.

2010-02-01

A fiber-optic RF distribution system has been developed for synchronizing lasers and RF plants in short pulse FELs. Typical requirements are 50-100fs rms over time periods from 1ms to several hours. Our system amplitude modulates a CW laser signal, senses fiber length using an interferometer, and feed-forward corrects the RF phase digitally at the receiver. We demonstrate less than 15fs rms error over 12 hours, between two independent channels with a fiber path length difference of 200m and transmitting S-band RF. The system is constructed using standard telecommunications components, and uses regular telecom fiber.

An Overview of the MaRIE X-FEL and Electron Radiography LINAC RF Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bradley, Joseph Thomas III; Rees, Daniel Earl; Scheinker, Alexander

The purpose of the Matter-Radiation Interactions in Extremes (MaRIE) facility at Los Alamos National Laboratory is to investigate the performance limits of materials in extreme environments. The MaRIE facility will utilize a 12 GeV linac to drive an X-ray Free-Electron Laser (FEL). Most of the same linac will also be used to perform electron radiography. The main linac is driven by two shorter linacs; one short linac optimized for X-FEL pulses and one for electron radiography. The RF systems have historically been the one of the largest single component costs of a linac. We will describe the details of themore » different types of RF systems required by each part of the linacs. Starting with the High Power RF system, we will present our methodology for the choice of RF system peak power and pulselength with respect to klystron parameters, modulator parameters, performance requirements and relative costs. We will also present an overview of the Low Level RF systems that are proposed for MaRIE and briefly describe their use with some proposed control schemes.« less

Tunable Q-Factor RF Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balcazar, Mario D.; Yonehara, Katsuya; Moretti, Alfred

Intense neutrino beam is a unique probe for researching beyond the standard model. Fermilab is the main institution to produce the most powerful and widespectrum neutrino beam. From that respective, a radiation robust beam diagnostic system is a critical element in order to maintain the quality of the neutrino beam. Within this context, a novel radiation-resistive beam profile monitor based on a gasfilled RF cavity is proposed. The goal of this measurement is to study a tunable Qfactor RF cavity to determine the accuracy of the RF signal as a function of the quality factor. Specifically, measurement error of themore » Q-factor in the RF calibration is investigated. Then, the RF system will be improved to minimize signal error.« less

Direct thrust measurement of a permanent magnet helicon double layer thruster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, K.; Lafleur, T.; Charles, C.

2011-04-04

Direct thrust measurements of a permanent magnet helicon double layer thruster have been made using a pendulum thrust balance and a high sensitivity laser displacement sensor. At the low pressures used (0.08 Pa) an ion beam is detected downstream of the thruster exit, and a maximum thrust force of about 3 mN is measured for argon with an rf input power of about 700 W. The measured thrust is proportional to the upstream plasma density and is in good agreement with the theoretical thrust based on the maximum upstream electron pressure.

[Cerebrovascular risk factors seen in a university hospital].

PubMed

Hernández Chávez, M; Samsó Zepeda, C; López Espejo, M; Escobar Henríquez, R; Mesa Latorre, T

2014-09-01

Risk factors (RF) in pediatric stroke differ from those of adults, and they include a wide range of diseases such as heart disease, infections, leukemias, and inborn errors of metabolism. To describe RF for ischemic stroke in a pediatric population, and to examine the relationship of RF with age, sex and type of stroke. An analysis was made of database of 114 children and adolescents with ischemic stroke from January 2003 to July 2012. Risk factors were stratified into 6 categories and ischemic strokes were classified as arterial and venous. We compared the RF with age, sex, and type of stroke (chi2 and OR). The median age was 2.5 years, with 74 (62.2%) males. No RF was identified in 7.9% of patients, and 67% had more than one RF. The most common RF were acute systemic diseases (56.1%), heart disease (35.1%), and chronic systemic diseases (29.8%). There was a statistically significant association between acute systemic disease and age less than 5 years (P<.001), and between chronic systemic disease and age 5 years or more (P<.02). The RF of heart disease was associated with arterial infarction (P<.05), and the acute head and neck disease RF was associated with venous infarction (P<.05). The RF for ischemic stroke are multiple in the pediatric population, and some of them are associated with a specific age and type of stroke. The detection of these factors may help in the primary prevention of people at risk, an early diagnosis, and treatment and prevention of recurrences. Copyright © 2013 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.

RF and Optical Communications: A Comparison of High Data Rate Returns From Deep Space in the 2020 Timeframe

NASA Technical Reports Server (NTRS)

Williams, W. Dan; Collins, Michael; Boroson, Don M.; Lesh, James; Biswas, Abihijit; Orr, Richard; Schuchman, Leonard; Sands, O. Scott

2007-01-01

As NASA proceeds with plans for increased science data return and higher data transfer capacity for science missions, both RF and optical communications are viable candidates for significantly higher-rate communications from deep space to Earth. With the inherent advantages, smaller apertures and larger bandwidths, of optical communications, it is reasonable to expect that at some point in time and combination of increasing distance and data rate, the rapidly emerging optical capabilities would become more advantageous than the more mature and evolving RF techniques. This paper presents a comparison of the burden to a spacecraft by both RF and optical communications systems for data rates of 10, 100, and 1000 Mbps and large distances. Advanced technology for RF and optical communication systems have been considered for projecting capabilities in the 2020 timeframe. For the comparisons drawn, the optical and RF ground terminals were selected to be similar in cost. The RF system selected is composed of forty-five 12-meter antennas, whereas the selected optical system is equivalent to a 10-meter optical telescope. Potential differences in availability are disregarded since the focus of this study is on spacecraft mass and power burden for high-rate mission data, under the assumption that essential communications will be provided by low-rate, high availability RF. For both the RF and optical systems, the required EIRP, for a given data rate and a given distance, was achieved by a design that realized the lowest possible communications subsystem mass (power + aperture) consistent with achieving the lowest technology risk. A key conclusion of this paper is that optical communications has great potential for high data rates and distances of 2.67 AU and beyond, but requires R&D and flight demonstrations to prove out technologies.

Measuring the residual stress of transparent conductive oxide films on PET by the double-beam shadow Moiré interferometer

NASA Astrophysics Data System (ADS)

Chen, Hsi-Chao; Huang, Kuo-Ting; Lo, Yen-Ming; Chiu, Hsuan-Yi; Chen, Guan-Jhen

2011-09-01

The purpose of this research was to construct a measurement system which can fast and accurately analyze the residual stress of the flexible electronics. The transparent conductive oxide (TCO) films, tin-doped indium oxide (ITO), were deposited by radio frequency (RF) magnetron sputtering using corresponding oxide targets on PET substrate. As we know that the shadow Moiré interferometry is a useable way to measure the large deformation. So we set up a double beam shadow Moiré interferometer to measure and analyze the residual stress of TCO films on PET. The feature was to develop a mathematical model and combine the image processing software. By the LabVIEW graphical software, we could measure the distance which is between the left and right fringe on the pattern to solve the curvature of deformed surface. Hence, the residual stress could calculate by the Stoney correction formula for the flexible electronics. By combining phase shifting method with shadow Moiré, the measurement resolution and accuracy have been greatly improved. We also had done the error analysis for the system whose relative error could be about 2%. Therefore, shadow Moiré interferometer is a non-destructive, fast, and simple system for the residual stress on TCO/PET films.

RF signal detection by a tunable optoelectronic oscillator based on a PS-FBG.

PubMed

Shao, Yuchen; Han, Xiuyou; Li, Ming; Zhao, Mingshan

2018-03-15

Low-power radio frequency (RF) signal detection is highly desirable for many applications, ranging from wireless communication to radar systems. A tunable optoelectronic oscillator (OEO) based on a phase-shifted fiber Bragg grating for detecting low-power RF signals is proposed and experimentally demonstrated. When the frequency of the input RF signal is matched with the potential oscillation mode of the OEO, it is detected and amplified. The frequency of the RF signal under detection can be estimated simultaneously by scanning the wavelength of the laser source. The RF signals from 1.5 to 5 GHz as low as -91  dBm are detected with a gain of about 10 dB, and the frequency is estimated with an error of ±100  MHz. The performance of the OEO system for detecting an RF signal with different modulation rates is also investigated.

The efficiency of photovoltaic cells exposed to pulsed laser light

NASA Technical Reports Server (NTRS)

Lowe, R. A.; Landis, G. A.; Jenkins, P.

1993-01-01

Future space missions may use laser power beaming systems with a free electron laser (FEL) to transmit light to a photovoltaic array receiver. To investigate the efficiency of solar cells with pulsed laser light, several types of GaAs, Si, CuInSe2, and GaSb cells were tested with the simulated pulse format of the induction and radio frequency (RF) FEL. The induction pulse format was simulated with an 800-watt average power copper vapor laser and the RF format with a frequency-doubled mode-locked Nd:YAG laser. Averaged current vs bias voltage measurements for each cell were taken at various optical power levels and the efficiency measured at the maximum power point. Experimental results show that the conversion efficiency for the cells tested is highly dependent on cell minority carrier lifetime, the width and frequency of the pulses, load impedance, and the average incident power. Three main effects were found to decrease the efficiency of solar cells exposed to simulated FEL illumination: cell series resistance, LC 'ringing', and output inductance. Improvements in efficiency were achieved by modifying the frequency response of the cell to match the spectral energy content of the laser pulse with external passive components.

An experimental system for symmetric capacitive rf discharge studies

NASA Astrophysics Data System (ADS)

Godyak, V. A.; Piejak, R. B.; Alexandrovich, B. M.

1990-09-01

An experimental system has been designed and built to comprehensively study the electrical and plasma characteristics in symmetric capacitively coupled rf discharges at low gas pressures. Descriptions of the system concept, the discharge chamber, the vacuum-gas control system, and the rf matching and electrical measurement system are presented together with some results of electrical measurements carried out in an argon discharge at 13.56 MHz. The system has been specifically designed to facilitate external discharge parameter measurements and probe measurements and to be compatible with a wide variety of other diagnostics. External electrical measurements and probe measurements within the discharge show that it is an ideal vehicle to study low-pressure rf discharge physics. Measurements from this system should be comparable to one-dimensional rf symmetric capacitive discharge theories and may help to verify them. Although only a few results are given here, the system has been operated reliably over a wide range of gas pressures and should give reproducible and accurate results for discharge electrical characteristics and plasma parameters over a wide range of driving frequency and gas components.

Divergent fifteen-year trends in traditional and cardiometabolic risk factors of cardiovascular diseases in the Seychelles

PubMed Central

Bovet, Pascal; Romain, Sarah; Shamlaye, Conrad; Mendis, Shanti; Darioli, Roger; Riesen, Walter; Tappy, Luc; Paccaud, Fred

2009-01-01

Objective Few studies have assessed secular changes in the levels of cardiovascular risk factors (CV-RF) in populations of low or middle income countries. The systematic collection of a broad set of both traditional and metabolic CV-RF in 1989 and 2004 in the population of the Seychelles islands provides a unique opportunity to examine trends at a fairly early stage of the "diabesity" era in a country in the African region. Methods Two examination surveys were conducted in independent random samples of the population aged 25–64 years in 1989 and 2004, attended by respectively 1081 and 1255 participants (participation rates >80%). All results are age-standardized to the WHO standard population. Results In 2004 vs. 1989, the levels of the main traditional CV-RF have either decreased, e.g. smoking (17% vs. 30%, p < 0.001), mean blood pressure (127.8/84.8 vs. 130.0/83.4 mmHg, p < 0.05), or only moderately increased, e.g. median LDL-cholesterol (3.58 vs. 3.36 mmol/l, p < 0. 01). In contrast, marked detrimental trends were found for obesity (37% vs. 21%, p < 0.001) and several cardiometabolic CVD-RF, e.g. mean HDL-cholesterol (1.36 vs. 1.40 mmol/l, p < 0.05), median triglycerides (0.80 vs. 0.78 mmol/l, p < 0.01), mean blood glucose (5.89 vs. 5.22 mmol/l, p < 0.001), median insulin (11.6 vs. 8.3 μmol/l, p < 0.001), median HOMA-IR (2.9 vs. 1.8, p < 0.001) and diabetes (9.4% vs. 6.2%, p < 0.001). At age 40–64, the prevalence of elevated total cardiovascular risk tended to decrease (e.g. WHO-ISH risk score ≥10; 11% vs. 13%, ns), whereas the prevalence of the metabolic syndrome (which integrates several cardiometabolic CVD-RF) nearly doubled (36% vs. 20%, p < 0.001). Data on physical activity and on intake of alcohol, fruit and vegetables are also provided. Awareness and treatment rates improved substantially for hypertension and diabetes, but control rates improved for the former only. Median levels of the cardiometabolic CVD-RF increased between 1989 and 2004 within all BMI strata, suggesting that the worsening levels of cardiometabolic CVD-RF in the population were not only related to increasing BMI levels in the interval. Conclusion The levels of several traditional CVD-RF improved over time, while marked detrimental trends were observed for obesity, diabetes and several cardiometabolic factors. Thus, in this population, the rapid health transition was characterized by substantial changes in the patterns of CVD-RF. More generally, this analysis suggests the importance of surveillance systems to identify risk factor trends and the need for preventive strategies to promote healthy lifestyles and nutrition. PMID:19558646

An RF amplifier for ICRF studies in the LAPD

NASA Astrophysics Data System (ADS)

Martin, M. J.; Pribyl, P.; Gekelman, W.; Lucky, Z.

2015-12-01

An RF amplifier system was designed and is under construction at the UCLA Basic Plasma Science Facility. The system is designed to output 200 kW peak RMS power at 1% duty cycle with a 1 Hz rep rate at frequencies of 2-6 MHz. This paper describes the RF amplifier system with preliminary benchmarks. Current design challenges and future work are discussed.

Rf system for the NSLS coherent infrared radiation source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Broome, W.; Biscardi, R.; Keane, J.

1995-05-01

The existing NSLS X-ray Lithography Source (XLS Phase I) is being considered for a coherent synchrotron radiation source. The existing 211 MHz warm cavity will be replaced with a 5-cell 2856 MHz superconducting RF cavity, driven by a series of 2 kW klystrons. The RF system will provide a total V{sub RF} of 1.5 MV to produce {sigma}{sub L} = 0.3 mm electron bunches at an energy of 150 MeV. Superconducting technology significantly reduces the required space and power needed to achieve the higher voltage. It is the purpose of this paper to describe the superconducting RF system and cavity,more » power requirements, and cavity design parameters such as input coupling, Quality Factor, and Higher Order Modes.« less

RF cavity using liquid dielectric for tuning and cooling

DOEpatents

Popovic, Milorad [Warrenville, IL; Johnson, Rolland P [Newport News, VA

2012-04-17

A system for accelerating particles includes an RF cavity that contains a ferrite core and a liquid dielectric. Characteristics of the ferrite core and the liquid dielectric, among other factors, determine the resonant frequency of the RF cavity. The liquid dielectric is circulated to cool the ferrite core during the operation of the system.

Optimization of a RF-generated CF4/O2 gas plasma sterilization process.

PubMed

Lassen, Klaus S; Nordby, Bolette; Grün, Reinar

2003-05-15

A sterilization process with the use of RF-generated (13.56 MHz) CF(4)/O(2) gas plasma was optimized in regards to power, flow rate, exposure time, and RF-system type. The dependency of the sporicidal effect on the spore inoculum positioning in the chamber of the RF systems was also investigated. Dried Bacillus stearothermophilus ATCC 7953 endospores were used as test organisms. The treatments were evaluated on the basis of survival curves and corresponding D values. The only parameter found to affect the sterilization process was the power of the RF system. Higher power resulted in higher kill. Finally, when the samples were placed more than 3-8 cm away from a centrally placed electrode in System 2, the sporicidal effect was reduced. The results are discussed and compared to results from the present literature. The RF excitation source is evaluated to be more appropriate for sterilization processes than the MW source. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 65B: 239-244, 2003

III-N light emitting diodes fabricated using RF nitrogen gas source MBE

NASA Astrophysics Data System (ADS)

Van Hove, J. M.; Carpenter, G.; Nelson, E.; Wowchak, A.; Chow, P. P.

1996-07-01

Homo- and heterojunction III-N light emitting diodes using RF atomic nitrogen plasma molecular beam epitaxy have been grown. GaN films deposited on sapphire using this growth technique exhibited an extremely sharp X-ray diffraction with a full width half maximum of 112 arc sec. p-type doping of the nitride films was done with elemental Mg and resulted in as-grown p-type material with resistivities as low as 2 Ω · cm. Both homo- and heterojunction LEDs showed clear rectification. Emission from the GaN homojunction deposited on n-type SiC was peaked at 410 nm while the AlGaNGaN(Zn)AlGaN double heterojunction LEDs emission was centered about 520 nm.

Ecological mechanisms underlying the sustainability of the agricultural heritage rice-fish coculture system.

PubMed

Xie, Jian; Hu, Liangliang; Tang, Jianjun; Wu, Xue; Li, Nana; Yuan, Yongge; Yang, Haishui; Zhang, Jiaen; Luo, Shiming; Chen, Xin

2011-12-13

For centuries, traditional agricultural systems have contributed to food and livelihood security throughout the world. Recognizing the ecological legacy in the traditional agricultural systems may help us develop novel sustainable agriculture. We examine how rice-fish coculture (RF), which has been designated a "globally important agricultural heritage system," has been maintained for over 1,200 y in south China. A field survey demonstrated that although rice yield and rice-yield stability are similar in RF and rice monoculture (RM), RF requires 68% less pesticide and 24% less chemical fertilizer than RM. A field experiment confirmed this result. We documented that a mutually beneficial relationship between rice and fish develops in RF: Fish reduce rice pests and rice favors fish by moderating the water environment. This positive relationship between rice and fish reduces the need for pesticides in RF. Our results also indicate a complementary use of nitrogen (N) between rice and fish in RF, resulting in low N fertilizer application and low N release into the environment. These findings provide unique insights into how positive interactions and complementary use of resource between species generate emergent ecosystem properties and how modern agricultural systems might be improved by exploiting synergies between species.

Use of a compact range approach to evaluate rf and dual-mode missiles

NASA Astrophysics Data System (ADS)

Willis, Kenneth E.; Weiss, Yosef

2000-07-01

This paper describes a hardware-in-the-loop (HWIL) system developed for testing Radio Frequency (RF), Infra-Red (IR), and Dual-Mode missile seekers. The system consists of a unique hydraulic five-axis (three seeker axes plus two target axes) Flight Motion Table (FMT), an off-axis parabolic reflector, and electronics required to generate the signals to the RF feeds. RF energy that simulates the target is fed into the reflector from three orthogonal feeds mounted on the inner target axis, at the focal point area of the parabolic reflector. The parabolic reflector, together with the three RF feeds (the Compact Range), effectively produces a far-field image of the target. Both FMT target axis motion and electronic control of the RF beams (deflection) modify the simulated line-of-sight target angles. Multiple targets, glint, multi-path, ECM, and clutter can be introduced electronically. To evaluate dual-mode seekers, the center section of the parabolic reflector is replaced with an IR- transparent, but RF-reflective section. An IR scene projector mounts to the FMT target axes, with its image focused on the intersection of the FMT seeker axes. The system eliminates the need for a large anechoic chamber and 'Target Wall' or target motion system used with conventional HWIL systems. This reduces acquisition and operating costs of the facility.

Electromagnetic assessment of embedded micro antenna for a novel sphincter in the human body.

PubMed

Zan, Peng; Liu, Jinding; Ai, Yutao; Jiang, Enyu

2013-05-01

This paper presents a wireless, miniaturized, bi-directional telemetric artificial anal sphincter system that can be used for controlling patients' anal incontinence. The artificial anal sphincter system is mainly composed of an executive mechanism, a wireless power supply system and a wireless communication system. The wireless communication system consists of an internal RF transceiver, an internal RF antenna, a data transmission pathway, an external RF antenna and an external RF control transceiver. A micro NMHA (Normal Mode Helical Antenna) has been used for the transceiver of the internal wireless communication system and a quarter wave-length whip antenna of 7.75 cm has been used for the external wireless communication system. The RF carrier frequency of wireless communication is located in a license-free 433.1 MHz ISM (Industry, Science, and Medical) band. The radiation characteristics and SAR (Specific Absorption Rate) are evaluated using the finite difference time-domain method and 3D human body model. Results show that the SAR values of the antenna satisfy the ICNIRP (International Commission on Nonionizing Radiation Protection) limitations.

The effects of radiofrequency electromagnetic radiation on sperm function.

PubMed

Houston, B J; Nixon, B; King, B V; De Iuliis, G N; Aitken, R J

2016-12-01

Mobile phone usage has become an integral part of our lives. However, the effects of the radiofrequency electromagnetic radiation (RF-EMR) emitted by these devices on biological systems and specifically the reproductive systems are currently under active debate. A fundamental hindrance to the current debate is that there is no clear mechanism of how such non-ionising radiation influences biological systems. Therefore, we explored the documented impacts of RF-EMR on the male reproductive system and considered any common observations that could provide insights on a potential mechanism. Among a total of 27 studies investigating the effects of RF-EMR on the male reproductive system, negative consequences of exposure were reported in 21. Within these 21 studies, 11 of the 15 that investigated sperm motility reported significant declines, 7 of 7 that measured the production of reactive oxygen species (ROS) documented elevated levels and 4 of 5 studies that probed for DNA damage highlighted increased damage due to RF-EMR exposure. Associated with this, RF-EMR treatment reduced the antioxidant levels in 6 of 6 studies that discussed this phenomenon, whereas consequences of RF-EMR were successfully ameliorated with the supplementation of antioxidants in all 3 studies that carried out these experiments. In light of this, we envisage a two-step mechanism whereby RF-EMR is able to induce mitochondrial dysfunction leading to elevated ROS production. A continued focus on research, which aims to shed light on the biological effects of RF-EMR will allow us to test and assess this proposed mechanism in a variety of cell types. © 2016 Society for Reproduction and Fertility.

Advancement of In-Flight Alumina Powder Spheroidization Process with Water Droplet Injection Using a Small Power DC-RF Hybrid Plasma Flow System

NASA Astrophysics Data System (ADS)

Jang, Juyong; Takana, Hidemasa; Park, Sangkyu; Nishiyama, Hideya

2012-09-01

The correlation between plasma thermofluid characteristics and alumina powder spheroidization processes with water droplet injection using a small power DC-RF hybrid plasma flow system was experimentally clarified. Micro-sized water droplets with a low water flow rate were injected into the tail of thermal plasma flow so as not to disturb the plasma flow directly. Injected water droplets were vaporized in the thermal plasma flow and were transported upstream in the plasma flow to the torch by the backflow. After dissociation of water, the production of hydrogen was detected by the optical emission spectroscopy in the downstream RF plasma flow. The emission area of the DC plasma jet expanded and elongated in the vicinity of the RF coils. Additionally, the emission area of RF plasma flow enlarged and was visible as red emission in the downstream RF plasma flow in the vicinity below the RF coils due to hydrogen production. Therefore, the plasma flow mixed with produced hydrogen increased the plasma enthalpy and the highest spheroidization rate of 97% was obtained at a water flow rate of 15 Sm l/min and an atomizing gas flow rate of 8 S l/min using a small power DC-RF hybrid plasma flow system.

Study of the damage rate caused by intervertebral foramen type inside and outside and the pass of the intervertebral DRG RF puncture way.

PubMed

Sun, Jiashu; Zhang, Haitao

2014-09-01

This paper was to analyze and contrast the damage rate on the thoracic segment different position of the dorsal root ganglion(dorsal root ganglion, DRG) caused by different puncture path in radiofrequency ablation, thus the best RF target way for the thoracic segment of different types of DRG was confirmed. According to the difference of puncture and ablation damage way, 14 segmental spinal specimens were randomly divided into three groups, and then conducted DRG radiofrequency damage on percutaneous puncture path according to the type of DRG position.The damage effect of different puncture path by the judgment standard of the result of pathology analyzed. The experiment showed that RF damage of group A were 72.58 ± 18.88%, 54.16 ± 24.84% and 32.85 ± 28.11%; that of group B were 771.86 ± 15.15% and 72.02 ± 17.86%, 57.14 ± 18.02% and 52.47 ± 20.64%, 68.75 ± 14.63% and 71.78 ± 16.00%; and that of group C were 82.46 ± 14.10%, 81.53 ± 11.81% and 80.83 ± 13.33%. It was concluded that the singleness of DRG puncture route is one of the important reasons for the poor thoracic segments DRG radiofrequency (RF) ablation effect. While according to the type of DRG different positions with double joint puncture path can significantly improve the rate of DRG RF damage.

Mobile phone radiofrequency exposure has no effect on DNA double strand breaks (DSB) in human lymphocytes.

PubMed

Danese, Elisa; Lippi, Giuseppe; Buonocore, Ruggero; Benati, Marco; Bovo, Chiara; Bonaguri, Chiara; Salvagno, Gian Luca; Brocco, Giorgio; Roggenbuck, Dirk; Montagnana, Martina

2017-07-01

The use of mobile phones has been associated with an increased risk of developing certain type of cancer, especially in long term users. Therefore, this study was aimed to investigate the potential genotoxic effect of mobile phone radiofrequency exposure on human peripheral blood mononuclear cells in vitro. The study population consisted in 14 healthy volunteers. After collection of two whole blood samples, the former was placed in a plastic rack, 1 cm from the chassis of a commercial mobile phone (900 MHz carrier frequency), which was activated by a 30-min call. The second blood sample was instead maintained far from mobile phones or other RF sources. The influence of mobile phone RF on DNA integrity was assessed by analyzing γ-H2AX foci in lymphocytes using immunofluorescence staining kit on AKLIDES. No measure of γ-H2AX foci was significantly influenced by mobile phone RF exposure, nor mobile phone exposure was associated with significant risk of genetic damages in vitro (odds ratio comprised between 0.27 and 1.00). The results of this experimental study demonstrate that exposure of human lymphocytes to a conventional 900 MHz RF emitted by a commercial mobile phone for 30 min does not significantly impact DNA integrity.

Method of making radio frequency ion source antenna

DOEpatents

Ehlers, Kenneth W.; Leung, Ka-Ngo

1988-01-01

In the method, the radio frequency (RF) antenna is made by providing a clean coil made of copper tubing or other metal conductor, which is coated with a tacky organic binder, and then with a powdered glass frit, as by sprinkling the frit uniformly over the binder. The coil is then heated internally in an inert gas atmosphere, preferably by passing an electrical heating current along the coil. Initially, the coil is internally heated to about 200.degree. C. to boil off the water from the binder, and then to about 750.degree. C.-850.degree. C. to melt the glass frit, while also burning off the organic binder. The melted frit forms a molten glass coating on the metal coil, which is then cooled to solidify the glass, so that the metal coil is covered with a thin continuous homogeneous impervious glass coating of substantially uniform thickness. The glass coating affords complete electrical insulation and complete dielectric protection for the metal coil of the RF antenna, to withstand voltage breakdown and to prevent sputtering, while also doubling the plasma generating efficiency of the RF antenna, when energized with RF power in the vacuum chamber of an ion source for a particle accelerator or the like. The glass frit preferably contains apprxoimately 45% lead oxide.

Method of making radio frequency ion source antenna and such antenna

DOEpatents

Ehlers, K.W.; Leung, K.N.

1985-05-22

In the method, the radio frequency (rf) antenna is made by providing a clean coil made of copper tubing or other metal conductor, which is coated with a tacky organic binder, and then with a powdered glass frit, as by sprinkling the frit uniformly over the binder. The coil is then heated internally in an inert gas atmosphere, preferably by passing an electrical heating current along the coil. Initially, the coil is internally heated to about 200/sup 0/C to boil off the water from the binder, and then to about 750 to 850/sup 0/C to melt the glass frit, while also burning off the organic binder. The melted frit forms a molten glass coating on the metal coil, which is then cooled to solidify the glass, so that the metal coil is covered with a thin continuous homogeneous impervious glass coating of substantially uniform thickness. The glass coating affords complete electrical insulation and complete dielectric protection for the metal coil of the rf antenna, to withstand voltage breakdown and to prevent sputtering, while also doubling the plasma generating efficiency of the rf antenna, when energized with RF power in the vacuum chamber of an ion source for a particle accelerator or the like. The glass frit preferably contains approximately 45% lead oxide.

The design and implementation of a broadband digital low-level RF control system for the cyclotron accelerators at iThemba LABS

NASA Astrophysics Data System (ADS)

Duckitt, W. D.; Conradie, J. L.; van Niekerk, M. J.; Abraham, J. K.; Niesler, T. R.

2018-07-01

iThemba LABS has successfully designed a new broadband digital low-level RF control system for cyclotrons, that operates over the wide frequency range of 2-100 MHz and can achieve peak-peak amplitude and phase stabilities of 0.01% and 0.01°, respectively. The presented system performs direct digital synthesis (DDS) to directly convert the digital RF signals to analog RF and local-oscillator (LO) signals with 16-bit amplitude accuracy, programmable in steps of 1 μHz and 0.0001°. Down-conversion of the RF pick-up signals to an optimal intermediate frequency (IF) of 1 MHz and sampling of the IF channels by 16-bit, single sample-latency 10 MHz ADCs was implemented to allow digital high-speed low-latency in-phase/quadrature (I/Q) demodulation of the IF channels within the FPGA. This in turn allows efficient real-time digital closed-loop control of the amplitude and phase of the RF drive-signal to be achieved. The systems have been successfully integrated at iThemba LABS into the K = 8 and K = 10 injector cyclotrons (SPC1, and SPC2), the K = 200 separated sector cyclotron (SSC), the SSC flat-topping system, the pulse-selector system and the AX , J, and K-line RF bunchers. The systems have led to a substantial improvement in the beam quality of the SSC at iThemba LABS with a reduction in beam losses by more than 90%. The design, implementation and performance is discussed.

Screening and identification of gastric adenocarcinoma metastasis-related genes using cDNA microarray coupled to FDD-PCR.

PubMed

Wang, Jianhua; Chen, Shishu

2002-10-01

To identify certain gastric adenocarcinoma metastasis-related genes, an RF-1 cell line (primary tumor from a gastric adenocarcinoma patient) and an RF-48 cell line (its metastatic counterpart) were used as a model for studying the molecular mechanism of tumor metastasis. Two fluorescent cDNA probes, labeled with Cy3 and Cy5 dyes, were prepared from RF-1 and RF-48 mRNA samples by the reverse transcription method. The two color probes were then mixed and hybridized to a cDNA chip constructed with double-dots from 4,096 human genes, and scanned at two wavelengths. The experiment was repeated twice. Differentially expressedn genes from the above two cells were analyzed by use of computer. Of the total genes, 138 (3.4%) revealed differential expression in RF-48 cells compared with RF-1 cells: 81 (2.1%) genes revealed apparent up-regulation, and 56 (1.3%) genes revealed down-regulation. Forty-five genes involved in gastric adenocarcinoma metastasis were cloned using fluorescent differential display-PCR (FDD-PCR), including three novel genes. There were seven differentially expressed genes that presented the same behaviour under both detection methods. The possible roles of some differentially expressed genes, which may be involved in the mechanism of tumor metastasis, were discussed. cDNA chip was used to analyze gene expression in a high-throughput and large-scale manner in combination with FDD-PCR for cloning unknown novel genes. Some genes related to metastasis were preliminarily scanned, which would contribute to disclose the molecular mechanism of gastric adenocarcinoma metastasis and provide new targets for therapeutic intervention.

Up gradation of LHCD system for rf power level up to 2MW for SST1

NASA Astrophysics Data System (ADS)

Sharma, P. K.; Ambulkar, K. K.; Parmar, P. R.; Virani, C. G.; Thakur, A. L.; Kulkarni, S. V.; Lhcd Group

2010-02-01

To operate superconducting steadystate tokamak (SST1) for 1000 seconds, lower hybrid current drive (LHCD) system has been designed at a frequency of 3.7 GHz., which would couple 1.0 MW CW of microwave power to the shaped plasma. The system consists of various rf passive components and transmission line, employing which the rf power from the source is transported to the antenna. During calibration of transmission line, it was observed that the losses in the transmission line is substantial and eventually would lead to less coupled power to the plasma. Further it is anticipated that more LH power would be required for advanced operation of SST1 machine. Thus it is decided to upgrade the existing LHCD system to 2 MW CW power level. The proposed up gradation would demand several infra structural changes and needs to be addressed. Due to lack of space, we have proposed a scheme in which additional two klystrons, along with existing two klystrons would be accommodated in the existing space. The low rf power requirements have also been increased to cater the new needs. Accordingly additional cooling requirements have been proposed to accommodate the two new klystrons. The DAC and auxiliary power supplies have been also designed. The new up graded LHCD system would address several key technological issues. Firstly it would establish the operation of four klystrons at rated power in parallel employing single RHVPS (80kV, 70A). Secondly it would establish the operation of two high power klystrons operation at rated power when their collectors are cooled in series. In this paper we would present the various requirements for up-gradation of LHCD system to 2MW. The main requirements like high power rf source, along with modified support structure, low power rf systems to drive the high power rf source, auxiliary power supplies required for high power rf source, DAC system improvement, cooling improvements, etc. would be discussed.

Local gate control in carbon nanotube quantum devices

NASA Astrophysics Data System (ADS)

Biercuk, Michael Jordan

This thesis presents transport measurements of carbon nanotube electronic devices operated in the quantum regime. Nanotubes are contacted by source and drain electrodes, and multiple lithographically-patterned electrostatic gates are aligned to each device. Transport measurements of device conductance or current as a function of local gate voltages reveal that local gates couple primarily to the proximal section of the nanotube, hence providing spatially localized control over carrier density along the nanotube length. Further, using several different techniques we are able to produce local depletion regions along the length of a tube. This phenomenon is explored in detail for different contact metals to the nanotube. We utilize local gating techniques to study multiple quantum dots in carbon nanotubes produced both by naturally occurring defects, and by the controlled application of voltages to depletion gates. We study double quantum dots in detail, where transport measurements reveal honeycomb charge stability diagrams. We extract values of energy-level spacings, capacitances, and interaction energies for this system, and demonstrate independent control over all relevant tunneling rates. We report rf-reflectometry measurements of gate-defined carbon nanotube quantum dots with integrated charge sensors. Aluminum rf-SETs are electrostatically coupled to carbon nanotube devices and detect single electron charging phenomena in the Coulomb blockade regime. Simultaneous correlated measurements of single electron charging are made using reflected rf power from the nanotube itself and from the rf-SET on microsecond time scales. We map charge stability diagrams for the nanotube quantum dot via charge sensing, observing Coulomb charging diamonds beyond the first order. Conductance measurements of carbon nanotubes containing gated local depletion regions exhibit plateaus as a function of gate voltage, spaced by approximately 1e2/h, the quantum of conductance for a single (non-degenerate) mode. Plateau structure is investigated as a function of bias voltage, temperature, and magnetic field. We speculate on the origin of this surprising quantization, which appears to lack band and spin degeneracy.

An electromyographic analysis of selected asana in experienced yogic practitioners.

PubMed

Kelley, Kathleen; Slattery, Katherine; Apollo, Kaitlyn

2018-01-01

The purpose of this study was to assess electromyographic (EMG) output of the anterior tibialis (TA), medial head of the gastrocnemius (GA), rectus femoris (RF), bicep femoris (BF), and gluteus medius (GM) in experienced yogic practitioners during selected yoga asana. A secondary purpose was to examine the differences in EMG output in unilateral V. bilateral standing yoga asana. The study was a single occasion descriptive design. Thirteen healthy yoga practitioners (1 male, 12 females, average age of 37.5) with more than five years of experience were recruited. EMG activity was recorded during maximum voluntary isometric contractions (MVIC) of the TA, GA, RF, and BF using the Biodex Multijoint System ® , and GM using manual muscle testing position. Subjects then performed the following yoga asana while EMG activity was recorded: downward facing dog, half-moon, tree, chair, and warrior three pose. Each asana was held for fifteen seconds and performed three times. EMG data were band pass filtered and the root mean square was obtained. Asana data were then amplitude normalized with the subjects' MVIC data. Integrated EMG was calculated for TA, GA, RF, BF and GM, in each asana. A multilevel regression analysis was performed, and peak EMG data was compared. Analysis between muscles showed that during CH and DD EMG activity was greatest in the TA muscle compared to the other muscles, while during HM and WR the GA muscle showed the greatest activity. Analysis within muscles showed low GA, BF, and GM activity during chair pose and downward facing dog compared to half moon, tree, and warrior three, and high RF activity during chair compared to the other poses. In conclusion, there were differences in frontal and sagittal plane muscle activation between single limb and double limb poses in experienced yogic practitioners. Copyright © 2017. Published by Elsevier Ltd.

Transient effects in π-pulse sequences in MAS solid-state NMR

NASA Astrophysics Data System (ADS)

Hellwagner, Johannes; Wili, Nino; Ibáñez, Luis Fábregas; Wittmann, Johannes J.; Meier, Beat H.; Ernst, Matthias

2018-02-01

Dipolar recoupling techniques that use isolated rotor-synchronized π pulses are commonly used in solid-state NMR spectroscopy to gain insight into the structure of biological molecules. These sequences excel through their simplicity, stability towards radio-frequency (rf) inhomogeneity, and low rf requirements. For a theoretical understanding of such sequences, we present a Floquet treatment based on an interaction-frame transformation including the chemical-shift offset dependence. This approach is applied to the homonuclear dipolar-recoupling sequence Radio-Frequency Driven Recoupling (RFDR) and the heteronuclear recoupling sequence Rotational Echo Double Resonance (REDOR). Based on the Floquet approach, we show the influence of effective fields caused by pulse transients and discuss the advantages of pulse-transient compensation. We demonstrate experimentally that the transfer efficiency for homonuclear recoupling can be doubled in some cases in model compounds as well as in simple peptides if pulse-transient compensation is applied to the π pulses. Additionally, we discuss the influence of various phase cycles on the recoupling efficiency in order to reduce the magnitude of effective fields. Based on the findings from RFDR, we are able to explain why the REDOR sequence does not suffer in the recoupling efficiency despite the presence of effective fields.

Examining Innovative Divertor and Main Chamber Options for a National Divertor Test Tokamak

NASA Astrophysics Data System (ADS)

Labombard, B.; Umansky, M.; Brunner, D.; Kuang, A. Q.; Marmar, E.; Wallace, G.; Whyte, D.; Wukitch, S.

2016-10-01

The US fusion community has identified a compelling need for a National Divertor Test Tokamak. The 2015 Community Planning Workshop on PMI called for a national working group to develop options. Important elements of a NDTT, adopted from the ADX concept, include the ability to explore long-leg divertor `solutions for power exhaust and particle control' (Priority Research Direction B) and to employ inside-launch RF actuators combined with double-null topologies as `plasma solution for main chamber wall components, including tools for controllable sustained operation' (PRD-C). Here we examine new information on these ideas. The projected performance of super-X and X-point target long-leg divertors is looking very promising; a stable fully-detached divertor condition handling an order-of-magnitude increase in power handling over conventional divertors may be possible. New experiments on Alcator C-Mod are addressing issues of high-field side versus low-field side heat flux sharing in double-null topologies and the screening of impurities that might originate from RF actuators placed in the high-field side - both with favorable results. Supported by USDoE Awards DE-FC02-99ER54512 and DE-AC52-07NA27344.

Performance analysis of InGaAs/GaAsP heterojunction double gate tunnel field effect transistor

NASA Astrophysics Data System (ADS)

Ahish, S.; Sharma, Dheeraj; Vasantha, M. H.; Kumar, Y. B. N.

2017-03-01

In this paper, analog/RF performance of InGaAs/GaAsP heterojunction double gate tunnel field effect transistor (HJTFET) has been explored. A highly doped n+ layer is placed at the Source-Channel junction in order to improve the horizontal electric field component and thus, improve the realiability of the device. The analog performance of the device is analysed by extracting current-voltage characteristics, transcondutance (gm), gate-to-drain capacitance (Cgd) and gate-to-source capacitance (Cgs). Further, RF performance of the device is evaluated by obtaining cut-off frequency (fT) and Gain Bandwidth (GBW) product. ION /IOFF ratio equal to ≈ 109, subthreshold slope of 27 mV/dec, maximum fT of 2.1 THz and maximum GBW of 484 GHz were achieved. Also, the impact of temperature variation on the linearity performance of the device has been investigated. Furthermore, the circuit level performance of the device is performed by implementing a Common Source (CS) amplifier; maximum gain of 31.11 dB and 3-dB cut-off frequency equal to 91.2 GHz were achieved for load resistance (RL) = 17.5 KΩ.

The rf coil as a sensitive motion detector for magnetic resonance imaging.

PubMed

Buikman, D; Helzel, T; Röschmann, P

1988-01-01

A new sensor principle for detection of patient movement in magnetic resonance imaging has been successfully applied for the reduction of motion artifacts. It uses a device that is already present in every MRI system, namely the rf coil. Patient movement within the coil causes changes in the rf impedance match of the coil, which can be measured as variations in the reflected rf power. The principle used for the detection of respiratory and cardiac motion is described, and experimental results measured with several coil arrangements are given. Images are presented which were acquired with respiratory gating derived from the rf body coil of a 2 Tesla whole body MRI system.

A modified quadrupole mass spectrometer with custom RF link rods driver for remote operation

NASA Technical Reports Server (NTRS)

Tashbar, P. W.; Nisen, D. B.; Moore, W. W., Jr.

1973-01-01

A commercial quadrupole residual gas analyzer system has been upgraded for operation at extended cable lengths. Operation inside a vacuum chamber for the standard quadrupole nude head is limited to approximately 2 m from its externally located rf/dc generator because of the detuning of the rf oscillator circuits by the coaxial cable reactance. The advance of long distance remote operation inside a vacuum chamber for distances of 45 and 60 m was made possible without altering the quadrupole's rf/dc generator circuit by employing an rf link to drive the quadrupole rods. Applications of the system have been accomplished for in situ space simulation thermal/vacuum testing of sophisticated payloads.

[Study of anatomy of the lateral attachment of the renal fascia in adult with multidetector computed tomography].

PubMed

Qi, Rui; Zhou, Xianping; Yu, Jianqun; Chen, Weixia; Li, Zhenlin; Zhang, Chunle

2012-08-01

The present paper is aimed to observe the lateral attachment of the renal fascia (RF) in vivo with multidetector computed tomography (MDCT) scanning, and to discuss its diagnostic value. 121 healthy adults were adopted into this experiment. All images were obtained with MDCT and double phase enhancement scanning. Then we observed the lateral attachment of RF. In addition, we mad a fresh body specimen as anatomical basis. The study found that above the renal hilar plane (RHP), the anterior renal fascia laterally fused with the peritoneum of the liver on the right and the peritoneum of the spleen on the left,and the posterior renal fascia fused with the subdiaphragmatic fascia. The lateral attachment of the RF at the RHP and the lower renal pole(LRP)is divided into three types. The RF in Type I is about 47.9% (58/121) at the left RHP, while about 33.9% (41/121) at the right RHP. At the LRP of the kidney is about 55.3% (67/121) on the left, and about 42.1% (51/121) on the right. The RF in Type I is about 38.8% (47/121) on the left side at the RHP, about 26.4% (32/121) on the right side. At the LRP, left side about 27.3% (33/121), right side about 13.3%(16/121). The RF in Type III at the RHP is 13.3% (16/121) on the left side, and on the right side is about 39.7% (48/121). At the LRP, it is about 17.4% (21/121) on the left side, and about 44.6% (54/121) on the right side. MDCT can display the lateral attachment of the RF better as well as the outside connection of the retroperitoneal space.

A new RF window designed for high-power operation in an S-band LINAC RF system

NASA Astrophysics Data System (ADS)

Joo, Youngdo; Kim, Seung-Hwan; Hwang, Woonha; Ryu, Jiwan; Roh, Sungjoo

2016-09-01

A new RF window is designed for high-power operation at the Pohang Light Source-II (PLSII) S-band linear accelerator (LINAC) RF system. In order to reduce the strength of the electric field component perpendicular to the ceramic disk, which is commonly known as the main cause of most discharge breakdowns in ceramic disk, we replace the pill-box type cavity in the conventional RF window with an overmoded cavity. The overmoded cavity is coupled with input and output waveguides through dual side-wall coupling irises to reduce the electric field strength at the iris and the number of possible mode competitions. The finite-difference time-domain (FDTD) simulation, CST MWS, was used in the design process. The simulated maximum electric field component perpendicular to the ceramic for the new RF window is reduced by an order of magnitude compared with taht for the conventional RF window, which holds promise for stable high-power operation.

RF pulse compression for future linear colliders

NASA Astrophysics Data System (ADS)

Wilson, Perry B.

1995-07-01

Future (nonsuperconducting) linear colliders will require very high values of peak rf power per meter of accelerating structure. The role of rf pulse compression in producing this power is examined within the context of overall rf system design for three future colliders at energies of 1.0-1.5 TeV, 5 TeV, and 25 TeV. In order to keep the average AC input power and the length of the accelerator within reasonable limits, a collider in the 1.0-1.5 TeV energy range will probably be built at an x-band rf frequency, and will require a peak power on the order of 150-200 MW per meter of accelerating structure. A 5 TeV collider at 34 GHz with a reasonable length (35 km) and AC input power (225 MW) would require about 550 MW per meter of structure. Two-beam accelerators can achieve peak powers of this order by applying dc pulse compression techniques (induction linac modules) to produce the drive beam. Klystron-driven colliders achieve high peak power by a combination of dc pulse compression (modulators) and rf pulse compression, with about the same overall rf system efficiency (30-40%) as a two-beam collider. A high gain (6.8) three-stage binary pulse compression system with high efficiency (80%) is described, which (compared to a SLED-II system) can be used to reduce the klystron peak power by about a factor of two, or alternatively, to cut the number of klystrons in half for a 1.0-1.5 TeV x-band collider. For a 5 TeV klystron-driven collider, a high gain, high efficiency rf pulse compression system is essential.

Impact of a radio frequency management information system on the process and timing of providing respiratory care services.

PubMed

Stoller, James K; Kester, Lucy; Orens, Douglas K; McCarthy, Kevin

2002-08-01

Although radio frequency (RF) systems have proliferated and are designed to simplify care delivery in many clinical settings, little information is available on the impact of such RF systems on the delivery of patient care. Having used a hand-held-device-based management information system in our Respiratory Therapy Section for 16 years, we assessed the impact of an RF system on the delivery of respiratory therapy (RT) services. A single nursing unit dedicated to pulmonary and ear, nose, and throat care was selected for the RF system trial. Baseline (pre-RF) data were collected over 2 separate 1-month intervals (February 1999 and February 2000). The main outcome measures were (1) the amount of time needed at the beginning of the shift to organize and assign orders for RT services, (2) the time interval between notification of an RT consult order and completion of the RT consult, and (3) the time interval between notification of an RT treatment order and completion of the RT treatment. The activities required for organizing and assigning the orders were manually timed. Starting 6 weeks after therapists were trained to use the RF system, similar data were collected while using the RF system for two 1-month intervals (February and March 2001). The mean +/- SD time interval between receiving an RT consult order and completing the consult was reduced from 7.8 +/- 18.9 h to 2.8 +/- 2.4 h (p = 0.002). The percentage of patients who waited longer than 8 hours between receipt of a consult order and completion of the consult decreased from 18% to 4.7% (p = 0.026). The total time required for organizing and assigning RT work was reduced from 81.6 min to 43.6 min. The RF system had several advantages over the hand-held-device-based system: (1) shorter interval between the order for and completion of an RT consult, (2) lower percentage of patients for whom the interval between the order and the consult exceeded 8 hours, and (3) less time required to make shift assignments. These results invite assessment of whether accelerated delivery of RT services confers clinical benefits.

NASA Advanced Refrigerator/Freezer Technology Development Project Overview

NASA Technical Reports Server (NTRS)

Cairelli, J. E.

1995-01-01

NASA Lewis Research Center (LeRC) has recently initiated a three-year project to develop the advanced refrigerator/freezer (R/F) technologies needed to support future life and biomedical sciences space experiments. Refrigerator/freezer laboratory equipment, most of which needs to be developed, is enabling to about 75 percent of the planned space station life and biomedical science experiments. These experiments will require five different classes of equipment; three storage freezers operating at -20 C, -70 C and less than 183 C, a -70 C freeze-dryer, and a cryogenic (less than 183 C) quick/snap freezer. This project is in response to a survey of cooling system technologies, performed by a team of NASA scientists and engineers. The team found that the technologies, required for future R/F systems to support life and biomedical sciences spaceflight experiments, do not exist at an adequate state of development and concluded that a program to develop the advanced R/F technologies is needed. Limitations on spaceflight system size, mass, and power consumption present a significant challenge in developing these systems. This paper presents some background and a description of the Advanced R/F Technology Development Project, project approach and schedule, general description of the R/F systems, and a review of the major R/F equipment requirements.

FPGA-based RF interference reduction techniques for simultaneous PET–MRI

PubMed Central

Gebhardt, P; Wehner, J; Weissler, B; Botnar, R; Marsden, P K; Schulz, V

2016-01-01

Abstract The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) as a multi-modal imaging technique is considered very promising and powerful with regard to in vivo disease progression examination, therapy response monitoring and drug development. However, PET–MRI system design enabling simultaneous operation with unaffected intrinsic performance of both modalities is challenging. As one of the major issues, both the PET detectors and the MRI radio-frequency (RF) subsystem are exposed to electromagnetic (EM) interference, which may lead to PET and MRI signal-to-noise ratio (SNR) deteriorations. Early digitization of electronic PET signals within the MRI bore helps to preserve PET SNR, but occurs at the expense of increased amount of PET electronics inside the MRI and associated RF field emissions. This raises the likelihood of PET-related MRI interference by coupling into the MRI RF coil unwanted spurious signals considered as RF noise, as it degrades MRI SNR and results in MR image artefacts. RF shielding of PET detectors is a commonly used technique to reduce PET-related RF interferences, but can introduce eddy-current-related MRI disturbances and hinder the highest system integration. In this paper, we present RF interference reduction methods which rely on EM field coupling–decoupling principles of RF receive coils rather than suppressing emitted fields. By modifying clock frequencies and changing clock phase relations of digital circuits, the resulting RF field emission is optimised with regard to a lower field coupling into the MRI RF coil, thereby increasing the RF silence of PET detectors. Our methods are demonstrated by performing FPGA-based clock frequency and phase shifting of digital silicon photo-multipliers (dSiPMs) used in the PET modules of our MR-compatible Hyperion IID PET insert. We present simulations and magnetic-field map scans visualising the impact of altered clock phase pattern on the spatial RF field distribution, followed by MRI noise and SNR scans performed with an operating PET module using different clock frequencies and phase patterns. The methods were implemented via firmware design changes without any hardware modifications. This introduces new means of flexibility by enabling adaptive RF interference reduction optimisations in the field, e.g. when using a PET insert with different MRI systems or when different MRI RF coil types are to be operated with the same PET detector. PMID:27049898

FPGA-based RF interference reduction techniques for simultaneous PET-MRI.

PubMed

Gebhardt, P; Wehner, J; Weissler, B; Botnar, R; Marsden, P K; Schulz, V

2016-05-07

The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) as a multi-modal imaging technique is considered very promising and powerful with regard to in vivo disease progression examination, therapy response monitoring and drug development. However, PET-MRI system design enabling simultaneous operation with unaffected intrinsic performance of both modalities is challenging. As one of the major issues, both the PET detectors and the MRI radio-frequency (RF) subsystem are exposed to electromagnetic (EM) interference, which may lead to PET and MRI signal-to-noise ratio (SNR) deteriorations. Early digitization of electronic PET signals within the MRI bore helps to preserve PET SNR, but occurs at the expense of increased amount of PET electronics inside the MRI and associated RF field emissions. This raises the likelihood of PET-related MRI interference by coupling into the MRI RF coil unwanted spurious signals considered as RF noise, as it degrades MRI SNR and results in MR image artefacts. RF shielding of PET detectors is a commonly used technique to reduce PET-related RF interferences, but can introduce eddy-current-related MRI disturbances and hinder the highest system integration. In this paper, we present RF interference reduction methods which rely on EM field coupling-decoupling principles of RF receive coils rather than suppressing emitted fields. By modifying clock frequencies and changing clock phase relations of digital circuits, the resulting RF field emission is optimised with regard to a lower field coupling into the MRI RF coil, thereby increasing the RF silence of PET detectors. Our methods are demonstrated by performing FPGA-based clock frequency and phase shifting of digital silicon photo-multipliers (dSiPMs) used in the PET modules of our MR-compatible Hyperion II (D) PET insert. We present simulations and magnetic-field map scans visualising the impact of altered clock phase pattern on the spatial RF field distribution, followed by MRI noise and SNR scans performed with an operating PET module using different clock frequencies and phase patterns. The methods were implemented via firmware design changes without any hardware modifications. This introduces new means of flexibility by enabling adaptive RF interference reduction optimisations in the field, e.g. when using a PET insert with different MRI systems or when different MRI RF coil types are to be operated with the same PET detector.

FPGA-based RF interference reduction techniques for simultaneous PET-MRI

NASA Astrophysics Data System (ADS)

Gebhardt, P.; Wehner, J.; Weissler, B.; Botnar, R.; Marsden, P. K.; Schulz, V.

2016-05-01

The combination of positron emission tomography (PET) and magnetic resonance imaging (MRI) as a multi-modal imaging technique is considered very promising and powerful with regard to in vivo disease progression examination, therapy response monitoring and drug development. However, PET-MRI system design enabling simultaneous operation with unaffected intrinsic performance of both modalities is challenging. As one of the major issues, both the PET detectors and the MRI radio-frequency (RF) subsystem are exposed to electromagnetic (EM) interference, which may lead to PET and MRI signal-to-noise ratio (SNR) deteriorations. Early digitization of electronic PET signals within the MRI bore helps to preserve PET SNR, but occurs at the expense of increased amount of PET electronics inside the MRI and associated RF field emissions. This raises the likelihood of PET-related MRI interference by coupling into the MRI RF coil unwanted spurious signals considered as RF noise, as it degrades MRI SNR and results in MR image artefacts. RF shielding of PET detectors is a commonly used technique to reduce PET-related RF interferences, but can introduce eddy-current-related MRI disturbances and hinder the highest system integration. In this paper, we present RF interference reduction methods which rely on EM field coupling-decoupling principles of RF receive coils rather than suppressing emitted fields. By modifying clock frequencies and changing clock phase relations of digital circuits, the resulting RF field emission is optimised with regard to a lower field coupling into the MRI RF coil, thereby increasing the RF silence of PET detectors. Our methods are demonstrated by performing FPGA-based clock frequency and phase shifting of digital silicon photo-multipliers (dSiPMs) used in the PET modules of our MR-compatible Hyperion II D PET insert. We present simulations and magnetic-field map scans visualising the impact of altered clock phase pattern on the spatial RF field distribution, followed by MRI noise and SNR scans performed with an operating PET module using different clock frequencies and phase patterns. The methods were implemented via firmware design changes without any hardware modifications. This introduces new means of flexibility by enabling adaptive RF interference reduction optimisations in the field, e.g. when using a PET insert with different MRI systems or when different MRI RF coil types are to be operated with the same PET detector.

PEEL-AND-STICK SENSORS POWERED BY DIRECTED RF ENERGY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalau-Keraly, Chrisopher; Daniel, George; Lee, Joseph

PARC, a Xerox Company, is developing a low-cost system of peel-and-stick wireless sensors that will enable widespread building environment sensor deployment with the potential to deliver up to 30% energy savings. The system is embodied by a set of RF hubs that provide power to automatically located sensor nodes, and relay data wirelessly to the building management system (BMS). The sensor nodes are flexible electronic labels powered by rectified RF energy transmitted by an RF hub and can contain multiple printed and conventional sensors. The system design overcomes limitations in wireless sensors related to power delivery, lifetime, and cost bymore » eliminating batteries and photovoltaic devices. Sensor localization is performed automatically by the inclusion of a programmable multidirectional antenna array in the RF hub. Comparison of signal strengths while the RF beam is swept allows for sensor localization, reducing installation effort and enabling automatic recommissioning of sensors that have been relocated, overcoming a significant challenge in building operations. PARC has already demonstrated wireless power and temperature data transmission up to a distance of 20m with less than one minute between measurements, using power levels well within the FCC regulation limits in the 902-928 MHz ISM band. The sensor’s RF energy harvesting antenna achieves high performance with dimensions below 5cm x 9cm.« less

Peel-and-Stick Sensors Powered by Directed RF Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalau-Keraly, Christopher; Daniel, George; Lee, Joseph

PARC, a Xerox Company, is developing a low-cost system of peel-and-stick wireless sensors that will enable widespread building environment sensor deployment with the potential to deliver up to 30% energy savings. The system is embodied by a set of RF hubs that provide power to automatically located sensor nodes, and relay data wirelessly to the building management system (BMS). The sensor nodes are flexible electronic labels powered by rectified RF energy transmitted by an RF hub and can contain multiple printed and conventional sensors. The system design overcomes limitations in wireless sensors related to power delivery, lifetime, and cost bymore » eliminating batteries and photovoltaic devices. Sensor localization is performed automatically by the inclusion of a programmable multidirectional antenna array in the RF hub. Comparison of signal strengths while the RF beam is swept allows for sensor localization, reducing installation effort and enabling automatic recommissioning of sensors that have been relocated, overcoming a significant challenge in building operations. PARC has already demonstrated wireless power and temperature data transmission up to a distance of 20m with less than one minute between measurements, using power levels well within the FCC regulation limits in the 902-928 MHz ISM band. The sensor’s RF energy harvesting antenna achieves high performance with dimensions below 5cm x 9cm« less

RF Energy Harvesting Peel-and-Stick Sensors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalau-Keraly, Christopher; Schwartz, David; Daniel, George

PARC, a Xerox Company, is developing a low-cost system of peel-and-stick wireless sensors that will enable widespread building environment sensor deployment with the potential to deliver up to 30% energy savings. The system is embodied by a set of RF hubs that provide power to the automatically located sensor nodes, and relays data wirelessly to the building management system (BMS). The sensor nodes are flexible electronic labels powered by rectified RF energy transmitted by a RF hub and can contain multiple printed and conventional sensors. The system design overcomes limitations in wireless sensors related to power delivery, lifetime, and costmore » by eliminating batteries and photovoltaic devices. The sensor localization is performed automatically by the inclusion of a programmable multidirectional antenna array in the RF hub. Comparison of signal strengths when the RF beam is swept allows for sensor localization, further reducing installation effort and enabling automatic recommissioning of sensors that have been relocated, overcoming a significant challenge in building operations. PARC has already demonstrated wireless power and temperature data transmission up to a distance of 20m with a duty cycle less than a minute between measurements, using power levels well within the FCC regulation limits in the 902-928 MHz ISM band. The sensor’s RF energy harvesting antenna dimensions was less than 5cmx9cm, demonstrating the possibility of small form factor for the sensor nodes.« less

Intelligent signal analysis and recognition

NASA Technical Reports Server (NTRS)

Levinson, Robert; Helman, Daniel; Oswalt, Edward

1987-01-01

Progress in the research and development of self-organizing database system that can support the identification and characterization of signals in an RF environment is described. As the radio frequency spectrum becomes more crowded, there are a number of situations that require a characterization of the RF environment. This database system is designed to be practical in applications where communications and other instruments encounter a time varying and complex RF environment. The primary application of this system is the guidance and control of NASA's SETI Microwave Observing Project. Other possible applications include selection of telemety bands for communication with spacecraft, and the scheduling of antenna for radio astronomy are two examples where characterization of the RF environment is required. In these applications, the RF environment is constantly changing, and even experienced operators cannot quickly identify the multitude of signals that can be encountered. Some of these signals are repetitive, others appear to occur sporadically.

Commissioning and Early Operation for the NSLS-II Booster RF System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marques, C.; Cupolo, J.; Davila, P.

2015-05-03

The National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a third generation 3GeV, 500mA synchrotron light source. We discuss the booster synchrotron RF system responsible for providing power to accelerate an electron beam from 200MeV to 3GeV. The RF system design and construction are complete and is currently in the operational phase of the NSLS-II project. Preliminary operational data is also discussed.

Development and performance test of a new high power RF window in S-band PLS-II LINAC

NASA Astrophysics Data System (ADS)

Hwang, Woon-Ha; Joo, Young-Do; Kim, Seung-Hwan; Choi, Jae-Young; Noh, Sung-Ju; Ryu, Ji-Wan; Cho, Young-Ki

2017-12-01

A prototype of RF window was developed in collaboration with the Pohang Accelerator Laboratory (PAL) and domestic companies. High power performance tests of the single RF window were conducted at PAL to verify the operational characteristics for its application in the Pohang Light Source-II (PLS-II) linear accelerator (Linac). The tests were performed in the in-situ facility consisting of a modulator, klystron, waveguide network, vacuum system, cooling system, and RF analyzing equipment. The test results with Stanford linear accelerator energy doubler (SLED) have shown no breakdown up to 75 MW peak power with 4.5 μs RF pulse width at a repetition rate of 10 Hz. The test results with the current operation level of PLS-II Linac confirm that the RF window well satisfies the criteria for PLS-II Linac operation.

Sub-micron resolution rf cavity beam position monitor system at the SACLA XFEL facility

NASA Astrophysics Data System (ADS)

Maesaka, H.; Ego, H.; Inoue, S.; Matsubara, S.; Ohshima, T.; Shintake, T.; Otake, Y.

2012-12-01

We have developed and constructed a C-band (4.760 GHz) rf cavity beam position monitor (RF-BPM) system for the XFEL facility at SPring-8, SACLA. The demanded position resolution of the RF-BPM is less than 1 μm, because an electron beam and x-rays must be overlapped within 4 μm precision in the undulator section for sufficient FEL interaction between the electrons and x-rays. In total, 57 RF-BPMs, including IQ demodulators and high-speed waveform digitizers for signal processing, were produced and installed into SACLA. We evaluated the position resolutions of 20 RF-BPMs in the undulator section by using a 7 GeV electron beam having a 0.1 nC bunch charge. The position resolution was measured to be less than 0.6 μm, which was sufficient for the XFEL lasing in the wavelength region of 0.1 nm, or shorter.

Ex vivo mouse brain microscopy at 15T with loop-gap RF coil.

PubMed

Cohen, Ouri; Ackerman, Jerome L

2018-04-18

The design of a loop-gap-resonator RF coil optimized for ex vivo mouse brain microscopy at ultra high fields is described and its properties characterized using simulations, phantoms and experimental scans of mouse brains fixed in 10% formalin containing 4 mM Magnevist™. The RF (B 1 ) and magnetic field (B 0 ) homogeneities are experimentally quantified and compared to electromagnetic simulations of the coil. The coil's performance is also compared to a similarly sized surface coil and found to yield double the sensitivity. A three-dimensional gradient-echo (GRE) sequence is used to acquire high resolution mouse brain scans at (47 μm) 3 resolution in 1.8 h and a 20 × 20 × 19 μm 3 resolution in 27 h. The high resolution obtained permitted clear visualization and identification of multiple structures in the ex vivo mouse brain and represents, to our knowledge, the highest resolution ever achieved for a whole mouse brain. Importantly, the coil design is simple and easy to construct. Copyright © 2018 Elsevier Inc. All rights reserved.

Design simulations for a small emittance 2.7-cell photo-cathode rf-gun in jector

NASA Astrophysics Data System (ADS)

Yongzhang, Huang

1997-05-01

In order to produce the electron bunch with small emittance which is the key issue in the so-called SASE studies, the design studies on a two-and-half cell photocathode rf-gun has been conducted. The rf gun injector is optimized by using the code of Par mela. As a main result, the optimum is found to be a 2.7-cell cavity. The geometry and the coupling scheme of the requested cavity is studied in more detail with the codes of Mafia and Superfish. The beam iris of each cells is enlarged in order to wide n the mode separations. For the purpose of cancelling the influence of the coupling iris upon the field symmetry, the so-called symmetrical double-side input coupler is studied. The coupler will be assembled to the second cell and the critical matchin g has been achieved in the Mafia-T3 simulation. With this cavity, the final normalized rms emittance reaches the value of 0.81πmm-mrad at a charge of 1nC in the Parmela simulation.

DC and analog/RF performance optimisation of source pocket dual work function TFET

NASA Astrophysics Data System (ADS)

Raad, Bhagwan Ram; Sharma, Dheeraj; Kondekar, Pravin; Nigam, Kaushal; Baronia, Sagar

2017-12-01

We investigate a systematic study of source pocket tunnel field-effect transistor (SP TFET) with dual work function of single gate material by using uniform and Gaussian doping profile in the drain region for ultra-low power high frequency high speed applications. For this, a n+ doped region is created near the source/channel junction to decrease the depletion width results in improvement of ON-state current. However, the dual work function of the double gate is used for enhancement of the device performance in terms of DC and analog/RF parameters. Further, to improve the high frequency performance of the device, Gaussian doping profile is considered in the drain region with different characteristic lengths which decreases the gate to drain capacitance and leads to drastic improvement in analog/RF figures of merit. Furthermore, the optimisation is performed with different concentrations for uniform and Gaussian drain doping profile and for various sectional length of lower work function of the gate electrode. Finally, the effect of temperature variation on the device performance is demonstrated.

A new slip stacking RF system for a twofold power upgrade of Fermilab's Accelerator Complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madrak, Robyn

2014-05-15

Fermilab's Accelerator Complex has been recently upgraded, in order to increase the 120 GeV proton beam power on target from about 400 kW to over 700 kW for NOvA and other future intensity frontier experiments. One of the key ingredients of the upgrade is the offloading of some Main Injector synchrotron operations - beam injection and RF manipulation called ''slip stacking'' - to the 8GeV Recycler Ring, which had until recently been used only for low-intensity antiproton storage and cooling. This required construction of two new 53 MHz RF systems for the slip-stacking manipulations. The cavities operate simultaneously at Vmore » peak ≲150 kV, but at slightly different frequencies (Δf=1260 Hz). Their installation was completed in September 2013. This article describes the novel solutions used in the design of the new cavities, their tuning system, and the associated high power RF system. First results showing effective operation of the RF system, beam capture and successful slip-stacking in the Recycler Ring are presented.« less

Plasma characteristics of direct current enhanced cylindrical inductively coupled plasma source

NASA Astrophysics Data System (ADS)

Yue, HUA; Jian, SONG; Zeyu, HAO; Chunsheng, REN

2018-06-01

Experimental results of a direct current enhanced inductively coupled plasma (DCE-ICP) source which consists of a typical cylindrical ICP source and a plate-to-grid DC electrode are reported. With the use of this new source, the plasma characteristic parameters, namely, electron density, electron temperature and plasma uniformity, are measured by Langmuir floating double probe. It is found that DC discharge enhances the electron density and decreases the electron temperature, dramatically. Moreover, the plasma uniformity is obviously improved with the operation of DC and radio frequency (RF) hybrid discharge. Furthermore, the nonlinear enhancement effect of electron density with DC + RF hybrid discharge is confirmed. The presented observation indicates that the DCE-ICP source provides an effective method to obtain high-density uniform plasma, which is desirable for practical industrial applications.

rf measurements and tuning of the 750 MHz radio frequency quadrupole

NASA Astrophysics Data System (ADS)

Koubek, Benjamin; Grudiev, Alexej; Timmins, Marc

2017-08-01

In the framework of the program on medical applications a compact 750 MHz RFQ has been designed and built to be used as an injector for a hadron therapy linac. This RFQ was designed to accelerate protons to an energy of 5 MeV within only 2 m length. It is divided into four segments and equipped with 32 tuners in total. The length of the RFQ corresponds to 5 λ which is considered to be close to the limit for field adjustment using only piston tuners. Moreover the high frequency, which is about double the frequency of existing RFQs, results in a sensitive structure and requires careful tuning. In this paper we present the tuning algorithm, the tuning procedure and rf measurements of the RFQ.

Single-crystalline graphene radio-frequency nanoswitches

NASA Astrophysics Data System (ADS)

Li, Peng; Cui, Tianhong

2015-07-01

Growth of monolayer single-crystalline graphene (SCG) using the low-pressure chemical vapor deposition method is reported. Graphene’s superb quality and single-crystalline nature were characterized and verified by Raman microscopy, atomic force microscopy, and carrier mobility measurement. Radio-frequency (RF) nanoelectromechanical switches based on coplanar waveguide double-clamped SCG membrane were achieved, and the superb properties of SCG enable the switches to operate at a pull-in voltage as low as 1 V, with switch time in the nanosecond regime. Owing to their single-crystalline nature, the switches’ lifetime (>5000 times) is much longer than that of polycrystalline graphene ones reported. The RF devices exhibit good isolation (-30 dB at 40 GHz (Ka band)), which can be further improved by SCG’s conductivity variation due to actuation voltage.

High-powered microwave ablation with a small-gauge, gas-cooled antenna: initial ex vivo and in vivo results.

PubMed

Lubner, Meghan G; Hinshaw, J Louis; Andreano, Anita; Sampson, Lisa; Lee, Fred T; Brace, Christopher L

2012-03-01

To evaluate the performance of a gas-cooled, high-powered microwave system. Investigators performed 54 ablations in ex vivo bovine livers using three devices-a single 17-gauge cooled radiofrequency(RF) electrode; a cluster RF electrode; and a single 17-gauge, gas-cooled microwave (MW) antenna-at three time points (n = 6 at 4 minutes, 12 minutes, and 16 minutes). RF power was applied using impedance-based pulsing with maximum 200 W generator output. MW power of 135 W at 2.45 GHz was delivered continuously. An approved in vivo study was performed using 13 domestic pigs. Hepatic ablations were performed using single applicators and the above-mentioned MW and RF generator systems at treatment times of 2 minutes (n = 7 MW, n = 6 RF), 5 minutes (n = 23 MW, n = 8 RF), 7 minutes (n = 11 MW, n = 6 RF), and 10 minutes (n = 7 MW, n = 9 RF). Mean transverse diameter and length of the ablation zones were compared using analysis of variance (ANOVA) with post-hoc t tests and Wilcoxon rank-sum tests. Single ex vivo MW ablations were larger than single RF ablations at all time points (MW mean diameter range 3.5-4.8 cm 4-16 minutes; RF mean diameter range 2.6-3.1 cm 4-16 minutes) (P < .05). There was no difference in mean diameter between cluster RF and MW ablations (RF 3.3-4.4 cm 4-16 minutes; P = .4-.9). In vivo lesion diameters for MW (and RF) were as follows: 2.6 cm ± 0.72 (RF 1.5 cm ± 0.14), 3.6 cm ± 0.89 (RF 2.0 cm ± 0.4), 3.4 cm ± 0.87 (RF 1.8 cm ± 0.23), and 3.8 cm ± 0.74 (RF 2.1 cm ± 0.3) at 2 minutes, 5 minutes, 7 minutes, and 10 minutes (P < .05 all time points). Gas-cooled, high-powered MW ablation allows the generation of large ablation zones in short times. Copyright © 2012 SIR. Published by Elsevier Inc. All rights reserved.

Characterization of an Outdoor Ambient Radio Frequency Environment

DTIC Science & Technology

2016-02-16

radio frequency noise ”) prior to testing of a specific system under test (SUT). With this characterization, locations can be selected to avoid RF...spectrum analyzer, ambient RF noise floor, RF interference 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...environment (sometimes referred to as “radio frequency noise ”) prior to testing of a specific system under test (SUT). With this characterization

Overview of diagnostic implementation on Proto-MPEX at ORNL

NASA Astrophysics Data System (ADS)

Biewer, T. M.; Bigelow, T.; Caughman, J. B. O.; Fehling, D.; Goulding, R. H.; Gray, T. K.; Isler, R. C.; Martin, E. H.; Meitner, S.; Rapp, J.; Unterberg, E. A.; Dhaliwal, R. S.; Donovan, D.; Kafle, N.; Ray, H.; Shaw, G. C.; Showers, M.; Mosby, R.; Skeen, C.

2015-11-01

The Prototype Material Plasma Exposure eXperiment (Proto-MPEX) recently began operating with an expanded diagnostic set. Approximately 100 sightlines have been established, delivering the plasma light emission to a ``patch panel'' in the diagnostic room for distribution to a variety of instruments: narrow-band filter spectroscopy, Doppler spectroscopy, laser induced breakdown spectroscopy, optical emission spectroscopy, and Thomson scattering. Additional diagnostic systems include: IR camera imaging, in-vessel thermocouples, ex-vessel fluoroptic probes, fast pressure gauges, visible camera imaging, microwave interferometry, a retarding-field energy analyzer, rf-compensated and ``double'' Langmuir probes, and B-dot probes. A data collection and archival system has been initiated using the MDSplus format. This effort capitalizes on a combination of new and legacy diagnostic hardware at ORNL and was accomplished largely through student labor. This work was supported by the US. D.O.E. contract DE-AC05-00OR22725.

Multiband DSB-SC modulated radio over IsOWC link with coherent homodyne detection

NASA Astrophysics Data System (ADS)

Kang, Zong; Zhu, Jiang

2018-02-01

In this paper, we present a multiband double sideband-suppressed carrier (DSB-SC) modulated radio over intersatellite optical wireless communication (IsOWC) link with coherent homodyne detection. The proposed system can provide the transparent transport of multiband radio frequency (RF) signals with higher linearity and better receiver sensitivity than the intensity modulated with direct detection (IM/DD) scheme. The full system model and the exactly analytical expression of signal to noise and distortion ratio (SNDR) are derived considering the third-order intermodulation product and amplifier spontaneous emission (ASE) noise. The finite extinction ratio (ER) of Mach-Zehnder Modulator (MZM) and the saturation property of erbium doped fiber amplifier (EDFA) are also considered. Numerical results of SNDR with various numbers of subchannels and ERs are given. Results indicate that the optimal modulation index exists to maximize the SNDR and the power of local oscillator (LO) carrier should be within an appropriate range.

Overview of High Power Vacuum Dry RF Load Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasnykh, Anatoly

2015-08-27

A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is tomore » use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.« less

Performance evaluation of hybrid VLC using device cost and power over data throughput criteria

NASA Astrophysics Data System (ADS)

Lee, C. C.; Tan, C. S.; Wong, H. Y.; Yahya, M. B.

2013-09-01

Visible light communication (VLC) technology has attained its attention in both academic and industry lately. It is determined by the development of light emitting diode (LED) technology for solid-state lighting (SSL).It has great potential to gradually replace radio frequency (RF) wireless technology because it offers unregulated and unlicensed bandwidth to withstand future demand of indoor wireless access to real-time bandwidth-demanding applications. However, it was found to provide intrusive uplink channel that give rise to unpleasant irradiance from the user device which could interfere with the downlink channel of VLC and hence limit mobility to users as a result of small coverage (field of view of VLC).To address this potential problem, a Hybrid VLC system which integrates VLC (for downlink) and RF (for uplink) technology is proposed. It offers a non-intrusive RF back channel that provides high throughput VLC and maintains durability with conventional RF devices. To deploy Hybrid VLC system in the market, it must be energy and cost saving to attain its equivalent economical advantage by comparing to existing architecture that employs fluorescent or LED lights with RF technology. In this paper, performance evaluation on the proposed hybrid system was carried out in terms of device cost and power consumption against data throughput. Based on our simulation, Hybrid VLC system was found to reduce device cost by 3% and power consumption by 68% when compares to fluorescent lights with RF technology. Nevertheless, when it is compared to LED lights with RF technology, our proposed hybrid system is found to achieve device cost saving as high as 47% and reduced power consumption by 49%. Such promising results have demonstrated that Hybrid VLC system is a feasible solution and has paved the way for greater cost saving and energy efficient compares with the current RF architecture even with the increasing requirement of indoor area coverage.

Multi-level RF identification system

DOEpatents

Steele, Kerry D.; Anderson, Gordon A.; Gilbert, Ronald W.

2004-07-20

A radio frequency identification system having a radio frequency transceiver for generating a continuous wave RF interrogation signal that impinges upon an RF identification tag. An oscillation circuit in the RF identification tag modulates the interrogation signal with a subcarrier of a predetermined frequency and modulates the frequency-modulated signal back to the transmitting interrogator. The interrogator recovers and analyzes the subcarrier signal and determines its frequency. The interrogator generates an output indicative of the frequency of the subcarrier frequency, thereby identifying the responding RFID tag as one of a "class" of RFID tags configured to respond with a subcarrier signal of a predetermined frequency.

Genetic damage in human cells exposed to non-ionizing radiofrequency fields: a meta-analysis of the data from 88 publications (1990-2011).

PubMed

Vijayalaxmi; Prihoda, Thomas J

2012-12-12

Based on the 'limited' evidence suggesting an association between exposure to radiofrequency fields (RF) emitted from mobile phones and two types of brain cancer, glioma and acoustic neuroma, the International Agency for Research on Cancer has classified RF as 'possibly carcinogenic to humans' in group 2B. In view of this classification and the positive correlation between increased genetic damage and carcinogenesis, a meta-analysis was conducted to determine whether a significant increase in genetic damage in human cells exposed to RF provides a potential mechanism for its carcinogenic potential. The extent of genetic damage in human cells, assessed from various end-points, viz., single-/double-strand breaks in the DNA, incidence of chromosomal aberrations, micronuclei and sister chromatid exchanges, reported in a total of 88 peer-reviewed scientific publications during 1990-2011 was considered in the meta-analysis. Among the several variables in the experimental protocols used, the influence of five specific variables related to RF exposure characteristics was investigated: (i) frequency, (ii) specific absorption rate, (iii) exposure as continuous wave, pulsed wave and occupationally exposed/mobile phone users, (iv) duration of exposure, and (v) different cell types. The data indicated the following. (1) The magnitude of difference between RF-exposed and sham-/un-exposed controls was small with some exceptions. (2) In certain RF exposure conditions there was a statistically significant increase in genotoxicity assessed from some end-points: the effect was observed in studies with small sample size and was largely influenced by publication bias. Studies conducted within the generally recommended RF exposure guidelines showed a smaller effect. (3) The multiple regression analyses and heterogeneity goodness of fit data indicated that factors other than the above five variables as well as the quality of publications have contributed to the overall results. (4) More importantly, the mean indices for chromosomal aberrations, micronuclei and sister chromatid exchange end-points in RF-exposed and sham-/un-exposed controls were within the spontaneous levels reported in a large data-base. Thus, the classification of RF as possibly carcinogenic to humans in group 2B was not supported by genotoxicity-based mechanistic evidence. Copyright © 2012 Elsevier B.V. All rights reserved.

Loran digital phase-locked loop and RF front-end system error analysis

NASA Technical Reports Server (NTRS)

Mccall, D. L.

1979-01-01

An analysis of the system performance of the digital phase locked loops (DPLL) and RF front end that are implemented in the MINI-L4 Loran receiver is presented. Three of the four experiments deal with the performance of the digital phase locked loops. The other experiment deals with the RF front end and DPLL system error which arise in the front end due to poor signal to noise ratios. The ability of the DPLLs to track the offsets is studied.

Radio Frequency Microelectromechanical Systems [Book Chapter Manuscript

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nordquist, Christopher; Olsson, Roy H.

2014-12-15

Radio frequency microelectromechanical system (RF MEMS) devices are microscale devices that achieve superior performance relative to other technologies by taking advantage of the accuracy, precision, materials, and miniaturization available through microfabrication. To do this, these devices use their mechanical and electrical properties to perform a specific RF electrical function such as switching, transmission, or filtering. RF MEMS has been a popular area of research since the early 1990s, and within the last several years, the technology has matured sufficiently for commercialization and use in commercial market systems.

Process control monitoring systems, industrial plants, and process control monitoring methods

DOEpatents

Skorpik, James R [Kennewick, WA; Gosselin, Stephen R [Richland, WA; Harris, Joe C [Kennewick, WA

2010-09-07

A system comprises a valve; a plurality of RFID sensor assemblies coupled to the valve to monitor a plurality of parameters associated with the valve; a control tag configured to wirelessly communicate with the respective tags that are coupled to the valve, the control tag being further configured to communicate with an RF reader; and an RF reader configured to selectively communicate with the control tag, the reader including an RF receiver. Other systems and methods are also provided.

Design of double gate vertical tunnel field effect transistor using HDB and its performance estimation

NASA Astrophysics Data System (ADS)

Seema; Chauhan, Sudakar Singh

2018-05-01

In this paper, we demonstrate the double gate vertical tunnel field-effect transistor using homo/hetero dielectric buried oxide (HDB) to obtain the optimized device characteristics. In this concern, the existence of double gate, HDB and electrode work-function engineering enhances DC performance and Analog/RF performance. The use of electrostatic doping helps to achieve higher on-current owing to occurrence of higher tunneling generation rate of charge carriers at the source/epitaxial interface. Further, lightly doped drain region and high- k dielectric below channel and drain region are responsible to suppress the ambipolar current. Simulated results clarifies that proposed device have achieved the tremendous performance in terms of driving current capability, steeper subthreshold slope (SS), drain induced barrier lowering (DIBL), hot carrier effects (HCEs) and high frequency parameters for better device reliability.

Superconductor Digital-RF Receiver Systems

NASA Astrophysics Data System (ADS)

Mukhanov, Oleg A.; Kirichenko, Dmitri; Vernik, Igor V.; Filippov, Timur V.; Kirichenko, Alexander; Webber, Robert; Dotsenko, Vladimir; Talalaevskii, Andrei; Tang, Jia Cao; Sahu, Anubhav; Shevchenko, Pavel; Miller, Robert; Kaplan, Steven B.; Sarwana, Saad; Gupta, Deepnarayan

Digital superconductor electronics has been experiencing rapid maturation with the emergence of smaller-scale, lower-cost communications applications which became the major technology drivers. These applications are primarily in the area of wireless communications, radar, and surveillance as well as in imaging and sensor systems. In these areas, the fundamental advantages of superconductivity translate into system benefits through novel Digital-RF architectures with direct digitization of wide band, high frequency radio frequency (RF) signals. At the same time the availability of relatively small 4K cryocoolers has lowered the foremost market barrier for cryogenically-cooled digital electronic systems. Recently, we have achieved a major breakthrough in the development, demonstration, and successful delivery of the cryocooled superconductor digital-RF receivers directly digitizing signals in a broad range from kilohertz to gigahertz. These essentially hybrid-technology systems combine a variety of superconductor and semiconductor technologies packaged with two-stage commercial cryocoolers: cryogenic Nb mixed-signal and digital circuits based on Rapid Single Flux Quantum (RSFQ) technology, room-temperature amplifiers, FPGA processing and control circuitry. The demonstrated cryocooled digital-RF systems are the world's first and fastest directly digitizing receivers operating with live satellite signals in X-band and performing signal acquisition in HF to L-band at ˜30GHz clock frequencies.

An optically coupled system for quantitative monitoring of MRI-induced RF currents into long conductors.

PubMed

Zanchi, Marta G; Venook, Ross; Pauly, John M; Scott, Greig C

2010-01-01

The currents induced in long conductors such as guidewires by the radio-frequency (RF) field in magnetic resonance imaging (MRI) are responsible for potentially dangerous heating of surrounding media, such as tissue. This paper presents an optically coupled system with the potential to quantitatively measure the RF currents induced on these conductors. The system uses a self shielded toroid transducer and active circuitry to modulate a high speed light-emitting-diode transmitter. Plastic fiber guides the light to a photodiode receiver and transimpedance amplifier. System validation included a series of experiments with bare wires that compared wire tip heating by fluoroptic thermometers with the RF current sensor response. Validations were performed on a custom whole body 64 MHz birdcage test platform and on a 1.5 T MRI scanner. With this system, a variety of phenomena were demonstrated including cable trap current attenuation, lossy dielectric Q-spoiling and even transverse electromagnetic wave node patterns. This system should find applications in studies of MRI RF safety for interventional devices such as pacemaker leads, and guidewires. In particular, variations of this device could potentially act as a realtime safety monitor during MRI guided interventions.

A Mechanism of Unidirectional Transformation, Leading to Antibiotic Resistance, Occurs within Nasopharyngeal Pneumococcal Biofilm Consortia

PubMed Central

2018-01-01

ABSTRACT Streptococcus pneumoniae acquires genes for resistance to antibiotics such as streptomycin (Str) or trimethoprim (Tmp) by recombination via transformation of DNA released by other pneumococci and closely related species. Using naturally transformable pneumococci, including strain D39 serotype 2 (S2) and TIGR4 (S4), we studied whether pneumococcal nasopharyngeal transformation was symmetrical, asymmetrical, or unidirectional. Incubation of S2Tet and S4Str in a bioreactor simulating the human nasopharynx led to the generation of SpnTet/Str recombinants. Double-resistant pneumococci emerged soon after 4 h postinoculation at a recombination frequency (rF) of 2.5 × 10−4 while peaking after 8 h at a rF of 1.1 × 10−3. Acquisition of antibiotic resistance genes by transformation was confirmed by treatment with DNase I. A high-throughput serotyping method demonstrated that all double-resistant pneumococci belonged to one serotype lineage (S2Tet/Str) and therefore that unidirectional transformation had occurred. Neither heterolysis nor availability of DNA for transformation was a factor for unidirectional transformation given that the density of each strain and extracellular DNA (eDNA) released from both strains were similar. Unidirectional transformation occurred regardless of the antibiotic-resistant gene carried by donors or acquired by recipients and regardless of whether competence-stimulating peptide-receptor cross talk was allowed. Moreover, unidirectional transformation occurred when two donor strains (e.g., S4Str and S19FTmp) were incubated together, leading to S19FStr/Tmp but at a rF 3 orders of magnitude lower (4.9 × 10−6). We finally demonstrated that the mechanism leading to unidirectional transformation was due to inhibition of transformation of the donor by the recipient. PMID:29764945

Activity-based anorexia activates nesfatin-1 immunoreactive neurons in distinct brain nuclei of female rats.

PubMed

Scharner, Sophie; Prinz, Philip; Goebel-Stengel, Miriam; Lommel, Reinhard; Kobelt, Peter; Hofmann, Tobias; Rose, Matthias; Stengel, Andreas

2017-12-15

Activity-based anorexia (ABA) is an established animal model for the eating disorder anorexia nervosa (AN). The pathophysiology of AN and the involvement of food intake-regulatory peptides is still poorly understood. Nesfatin-1, an anorexigenic peptide also involved in the mediation of stress, anxiety and depression might be a likely candidate involved in the pathogenesis of AN. Therefore, activation of nesfatin-1 immunoreactive (ir) brain nuclei was investigated under conditions of ABA. Female Sprague-Dawley rats were used and divided into four groups (n=6/group): activity-based anorexia (ABA), restricted feeding (RF), activity (AC) and ad libitum fed (AL). After the 21-day experimental period and development of ABA, brains were processed for c-Fos/nesfatin-1 double labeling immunohistochemistry. ABA increased the number of nesfatin-1 immunopositive neurons in the paraventricular nucleus, arcuate nucleus, dorsomedial hypothalamic nucleus, locus coeruleus and in the rostral part of the nucleus of the solitary tract compared to AL and AC groups (p<0.05) but not to RF rats (p>0.05). Moreover, we observed significantly more c-Fos and nesfatin-1 ir double-labeled cells in ABA rats compared to RF, AL and AC in the supraoptic nucleus (p<0.05) and compared to AL and AC in the paraventricular nucleus, arcuate nucleus, dorsomedial hypothalamic nucleus, dorsal raphe nucleus and the rostral raphe pallidus (p<0.05). Since nesfatin-1 plays a role in the inhibition of food intake and the response to stress, we hypothesize that the observed changes of brain nesfatin-1 might play a role in the pathophysiology and symptomatology under conditions of ABA and potentially also in patients with AN. Copyright © 2017 Elsevier B.V. All rights reserved.

A low-level rf control system for a quarter-wave resonator

NASA Astrophysics Data System (ADS)

Kim, Jongwon; Hwang, Churlkew

2012-06-01

A low-level rf control system was designed and built for an rf deflector, which is a quarter wave resonator, and was designed to deflect a secondary electron beam to measure the bunch length of an ion beam. The deflector has a resonance frequency near 88 MHz, its required phase stability is approximately ±1° and its amplitude stability is less than ±1%. The control system consists of analog input and output components and a digital system based on a field-programmable gate array for signal processing. The system is cost effective, while meeting the stability requirements. Some basic properties of the control system were measured. Then, the capability of the rf control was tested using a mechanical vibrator made of a dielectric rod attached to an audio speaker system, which could induce regulated perturbations in the electric fields of the resonator. The control system was flexible so that its parameters could be easily configured to compensate for the disturbance induced in the resonator.

Quantitative evaluation of anatomical noise in chest digital tomosynthesis, digital radiography, and computed tomography

NASA Astrophysics Data System (ADS)

Lee, D.; Choi, S.; Lee, H.; Kim, D.; Choi, S.; Kim, H.-J.

2017-04-01

Lung cancer is currently the worldwide leading cause of death from cancer. Thus, detection of lung cancer at its early stages is critical for improving the survival rate of patients. Chest digital tomosynthesis (CDT) is a recently developed imaging modality, combining many advantages of digital radiography (DR) and computed tomography (CT). This method has the potential to be widely used in the clinical setting. In this study, we introduce a developed CDT R/F system and compare its image quality with those of DR and CT, especially with respect to anatomical noise and lung nodule conspicuity, for LUNGMAN phantoms. The developed CDT R/F system consists of a CsI scintillator flat panel detector, X-ray tube, and tomosynthesis data acquisition geometry. For CDT R/F imaging, 41 projections were acquired at different angles, over the ± 20° angular range, in a linear translation geometry. To evaluate the clinical effectiveness of the CDT R/F system, the acquired images were compared with CT (Philips brilliance CT 64, Philips healthcare, U.S.) and DR (ADR-M, LISTEM, Korea) phantom images in terms of the anatomical noise power spectrum (aNPS). DR images exhibited low conspicuity for a small-size lung nodule, while CDT R/F and CT exhibited relatively high sensitivity for all lung nodule sizes. The aNPS of the CDT R/F system was better than that of DR, by resolving anatomical overlapping problems. In conclusion, the developed CDT R/F system is likely to contribute to early diagnosis of lung cancer, while requiring a relatively low patient dose, compared with CT.

IBS and expected luminosity performance for RHIC beams at top energy with 56 MHz SRF cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fedotov,A.

The purpose of RF system in RHIC is to capture injected bunches, accelerate them to the top energy, and store bunches at the top energy for many hours. The accelerating RF system operates at harmonic number h=360 of the particle revolution frequency f=78.196 kHz, which corresponds to 28.15MHz. The storage RF system accepts the shortened bunches at top energy and provides longitudinal focusing to keep these bunches short during the store time (collision mode). The storage system operates at harmonic number h=7x360=2520, which corresponds to an RF frequency of 197.05 MHz [1]. Recently, an upgrade of storage RF system withmore » a superconducting 56 MHz cavity was proposed [2]. This upgrade will provide significant increase in the acceptance of storage RF bucket. Presently, the short bunch length for collisions is obtained via RF gymnastics with bunch rotation (called re-bucketing), because the length of 197MHz bucket of 5 nsec is too short to accommodate long bunches otherwise. However, due to bucket non-linearity and hardware complications some increase in the longitudinal emittance occurs during re-bucketing. The 56MHz cavity will produce sufficiently short bunches which would allow one to operate without re-bucketing procedure. This Note summarizes simulation of beam evolution due to Intra-beam scattering (IBS) for beam parameters expected with the 56 MHz SRF cavity upgrade. Expected luminosity improvement is shown both for Au ions at 100 GeV/nucleon and for protons at 250 GeV.« less

Development of new S-band RF window for stable high-power operation in linear accelerator RF system

NASA Astrophysics Data System (ADS)

Joo, Youngdo; Lee, Byung-Joon; Kim, Seung-Hwan; Kong, Hyung-Sup; Hwang, Woonha; Roh, Sungjoo; Ryu, Jiwan

2017-09-01

For stable high-power operation, a new RF window is developed in the S-band linear accelerator (Linac) RF systems of the Pohang Light Source-II (PLS-II) and the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The new RF window is designed to mitigate the strength of the electric field at the ceramic disk and also at the waveguide-cavity coupling structure of the conventional RF window. By replacing the pill-box type cavity in the conventional RF window with an overmoded cavity, the electric field component perpendicular to the ceramic disk that caused most of the multipacting breakdowns in the ceramic disk was reduced by an order of magnitude. The reduced electric field at the ceramic disk eliminated the Ti-N coating process on the ceramic surface in the fabrication procedure of the new RF window, preventing the incomplete coating from spoiling the RF transmission and lowering the fabrication cost. The overmoded cavity was coupled with input and output waveguides through dual side-wall coupling irises to reduce the electric field strength at the waveguide-cavity coupling structure and the possibility of mode competitions in the overmoded cavity. A prototype of the new RF window was fabricated and fully tested with the Klystron peak input power, pulse duration and pulse repetition rate of 75 MW, 4.5 μs and 10 Hz, respectively, at the high-power test stand. The first mass-produced new RF window installed in the PLS-II Linac is running in normal operation mode. No fault is reported to date. Plans are being made to install the new RF window to all S-band accelerator RF modules of the PLS-II and PAL-XFEL Linacs. This new RF window may be applied to the output windows of S-band power sources like Klystron as wells as the waveguide windows of accelerator facilities which operate in S-band.

Functional and Expression Analysis of the Metal-Inducible dmeRF System from Rhizobium leguminosarum bv. viciae

PubMed Central

Rubio-Sanz, L.; Prieto, R. I.; Imperial, J.; Brito, B.

2013-01-01

A gene encoding a homolog to the cation diffusion facilitator protein DmeF from Cupriavidus metallidurans has been identified in the genome of Rhizobium leguminosarum UPM791. The R. leguminosarum dmeF gene is located downstream of an open reading frame (designated dmeR) encoding a protein homologous to the nickel- and cobalt-responsive transcriptional regulator RcnR from Escherichia coli. Analysis of gene expression showed that the R. leguminosarum dmeRF genes are organized as a transcriptional unit whose expression is strongly induced by nickel and cobalt ions, likely by alleviating the repressor activity of DmeR on dmeRF transcription. An R. leguminosarum dmeRF mutant strain displayed increased sensitivity to Co(II) and Ni(II), whereas no alterations of its resistance to Cd(II), Cu(II), or Zn(II) were observed. A decrease of symbiotic performance was observed when pea plants inoculated with an R. leguminosarum dmeRF deletion mutant strain were grown in the presence of high concentrations of nickel and cobalt. The same mutant induced significantly lower activity levels of NiFe hydrogenase in microaerobic cultures. These results indicate that the R. leguminosarum DmeRF system is a metal-responsive efflux mechanism acting as a key element for metal homeostasis in R. leguminosarum under free-living and symbiotic conditions. The presence of similar dmeRF gene clusters in other Rhizobiaceae suggests that the dmeRF system is a conserved mechanism for metal tolerance in legume endosymbiotic bacteria. PMID:23934501

Fiber-Optic Network Architectures for Onboard Avionics Applications Investigated

NASA Technical Reports Server (NTRS)

Nguyen, Hung D.; Ngo, Duc H.

2003-01-01

This project is part of a study within the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Center. The main focus of the program is the improvement of air transportation, with particular emphasis on air transportation safety. Current and future advances in digital data communications between an aircraft and the outside world will require high-bandwidth onboard communication networks. Radiofrequency (RF) systems, with their interconnection network based on coaxial cables and waveguides, increase the complexity of communication systems onboard modern civil and military aircraft with respect to weight, power consumption, and safety. In addition, safety and reliability concerns from electromagnetic interference between the RF components embedded in these communication systems exist. A simple, reliable, and lightweight network that is free from the effects of electromagnetic interference and capable of supporting the broadband communications needs of future onboard digital avionics systems cannot be easily implemented using existing coaxial cable-based systems. Fiber-optical communication systems can meet all these challenges of modern avionics applications in an efficient, cost-effective manner. The objective of this project is to present a number of optical network architectures for onboard RF signal distribution. Because of the emergence of a number of digital avionics devices requiring high-bandwidth connectivity, fiber-optic RF networks onboard modern aircraft will play a vital role in ensuring a low-noise, highly reliable RF communication system. Two approaches are being used for network architectures for aircraft onboard fiber-optic distribution systems: a hybrid RF-optical network and an all-optical wavelength division multiplexing (WDM) network.

Box truss analysis and technology development. Task 1: Mesh analysis and control

NASA Technical Reports Server (NTRS)

Bachtell, E. E.; Bettadapur, S. S.; Coyner, J. V.

1985-01-01

An analytical tool was developed to model, analyze and predict RF performance of box truss antennas with reflective mesh surfaces. The analysis system is unique in that it integrates custom written programs for cord tied mesh surfaces, thereby drastically reducing the cost of analysis. The analysis system is capable of determining the RF performance of antennas under any type of manufacturing or operating environment by integrating together the various disciplines of design, finite element analysis, surface best fit analysis and RF analysis. The Integrated Mesh Analysis System consists of six separate programs: The Mesh Tie System Model Generator, The Loadcase Generator, The Model Optimizer, The Model Solver, The Surface Topography Solver and The RF Performance Solver. Additionally, a study using the mesh analysis system was performed to determine the effect of on orbit calibration, i.e., surface adjustment, on a typical box truss antenna.

Initial operation of high power ICRF system for long pulse in EAST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, C. M., E-mail: chmq@ipp.ac.cn; Zhao, Y. P.; Zhang, X. J.

2015-12-10

The ICRF heating system on EAST upgraded by active cooling aims for long pulse operation. In this paper, the main technical features of the ICRF system are described. One of a major challenges for long pulse operation is RF-edge interactions induced impurity production and heat loading. In EAST, ICRF antenna protections and Faraday screen bars damaged due to LH electron beam are found. Preliminary results for the analysis of the interaction between LHCD and ICRF antenna are discussed. Increase of metal impurities in the plasma during RF pulse and in a larger core radiation are also shown. These RF-edge interactionsmore » at EAST and some preliminary results for the optimizing RF performance will be presented.« less

The development of data acquisition and processing application system for RF ion source

NASA Astrophysics Data System (ADS)

Zhang, Xiaodan; Wang, Xiaoying; Hu, Chundong; Jiang, Caichao; Xie, Yahong; Zhao, Yuanzhe

2017-07-01

As the key ion source component of nuclear fusion auxiliary heating devices, the radio frequency (RF) ion source is developed and applied gradually to offer a source plasma with the advantages of ease of control and high reliability. In addition, it easily achieves long-pulse steady-state operation. During the process of the development and testing of the RF ion source, a lot of original experimental data will be generated. Therefore, it is necessary to develop a stable and reliable computer data acquisition and processing application system for realizing the functions of data acquisition, storage, access, and real-time monitoring. In this paper, the development of a data acquisition and processing application system for the RF ion source is presented. The hardware platform is based on the PXI system and the software is programmed on the LabVIEW development environment. The key technologies that are used for the implementation of this software programming mainly include the long-pulse data acquisition technology, multi-threading processing technology, transmission control communication protocol, and the Lempel-Ziv-Oberhumer data compression algorithm. Now, this design has been tested and applied on the RF ion source. The test results show that it can work reliably and steadily. With the help of this design, the stable plasma discharge data of the RF ion source are collected, stored, accessed, and monitored in real-time. It is shown that it has a very practical application significance for the RF experiments.

Radio-frequency energy quantification in magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Alon, Leeor

Mapping of radio frequency (RF) energy deposition has been challenging for 50+ years, especially, when scanning patients in the magnetic resonance imaging (MRI) environment. As result, electromagnetic simulation software is often used for estimating the specific absorption rate (SAR), the rate of RF energy deposition in tissue. The thesis work presents challenges associated with aligning information provided by electromagnetic simulation and MRI experiments. As result of the limitations of simulations, experimental methods for the quantification of SAR were established. A system for quantification of the total RF energy deposition was developed for parallel transmit MRI (a system that uses multiple antennas to excite and image the body). The system is capable of monitoring and predicting channel-by-channel RF energy deposition, whole body SAR and capable of tracking potential hardware failures that occur in the transmit chain and may cause the deposition of excessive energy into patients. Similarly, we demonstrated that local RF power deposition can be mapped and predicted for parallel transmit systems based on a series of MRI temperature mapping acquisitions. Resulting from the work, we developed tools for optimal reconstruction temperature maps from MRI acquisitions. The tools developed for temperature mapping paved the way for utilizing MRI as a diagnostic tool for evaluation of RF/microwave emitting device safety. Quantification of the RF energy was demonstrated for both MRI compatible and non-MRI-compatible devices (such as cell phones), while having the advantage of being noninvasive, of providing millimeter resolution and high accuracy.

Special Technology Area Review on Vacuum Electronics Technology for RF Applications

DTIC Science & Technology

2000-12-12

systems. QUESTIONS TO BE ADDRESSED AT THE STAR: 1. What are the RF applications and systems that will benefit from advances in Vacuum Electronic...technologies? What are the status and prospects of early insertion efforts? What is the impact if technology efforts are successful? 2. What are the RF...technical barriers best addressed by Vacuum Electronic technologies? What are the technology advancement needs and opportunities? Can the barriers

The alteration of spontaneous low frequency oscillations caused by acute electromagnetic fields exposure.

PubMed

Lv, Bin; Chen, Zhiye; Wu, Tongning; Shao, Qing; Yan, Duo; Ma, Lin; Lu, Ke; Xie, Yi

2014-02-01

The motivation of this study is to evaluate the possible alteration of regional resting state brain activity induced by the acute radiofrequency electromagnetic field (RF-EMF) exposure (30min) of Long Term Evolution (LTE) signal. We designed a controllable near-field LTE RF-EMF exposure environment. Eighteen subjects participated in a double-blind, crossover, randomized and counterbalanced experiment including two sessions (real and sham exposure). The radiation source was close to the right ear. Then the resting state fMRI signals of human brain were collected before and after the exposure in both sessions. We measured the amplitude of low frequency fluctuation (ALFF) and fractional ALFF (fALFF) to characterize the spontaneous brain activity. We found the decreased ALFF value around in left superior temporal gyrus, left middle temporal gyrus, right superior temporal gyrus, right medial frontal gyrus and right paracentral lobule after the real exposure. And the decreased fALFF value was also detected in right medial frontal gyrus and right paracentral lobule. The study provided the evidences that 30min LTE RF-EMF exposure modulated the spontaneous low frequency fluctuations in some brain regions. With resting state fMRI, we found the alteration of spontaneous low frequency fluctuations induced by the acute LTE RF-EMF exposure. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Negative ion kinetics in RF glow discharges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gottscho, R.A.; Gacbe, C.E.

1986-04-01

Using temporally and spatially resolved laser spectroscopy, the authors have determined the identities, approximate concentrations, effects on the local field, and kinetics of formation and loss of negative ions in RF discharges. CI/sup -/ and BCI/sub 3//sup -/ are the dominant negative ions found in low-frequency discharges through CI/sub 2/ and BCI/sub 3/, respectively. The electron affinity for CI is measured to be 3.6118 +- 0.0005 eV. Negative ion kinetics are strongly affected by application of the RF field. Formation of negative ions by attachment of slow electrons in RF discharges is governed by the extent and duration of electronmore » energy relaxation. Similarly, destruction of negative ions by collisional detachment and field extraction is dependent upon ion energy modulation. Thus, at low frequency, the anion density peaks at the beginning of the anodic and cathodic half-cycles after electrons have attached but before detachment and extraction have had time to occur. At higher frequencies, electrons have insufficient time to attach before they are reheated and the instantaneous anion density in the sheath is greatly reduced. When the negative ion density is comparable to the positive ion density, the plasma potential is observed to lie below the anode potential, double layers form between sheath and plasma, and anions and electrons are accelerated by large sheath fields to electrode surfaces.« less

A Model-Based Fast Protection System for High-Power RF Tube Amplifiers Used at the European XFEL Accelerator

NASA Astrophysics Data System (ADS)

Butkowski, Łukasz; Vogel, Vladimir; Schlarb, Holger; Szabatin, Jerzy

2017-06-01

The driving engine of the superconducting accelerator of the European X-ray free electron laser (XFEL) is a set of 27 radio frequency (RF) stations. Each of the underground RF stations consists of a multibeam horizontal klystron that can provide up to 10 MW of power at 1.3 GHz. Klystrons are sensitive devices with a limited lifetime and a high mean time between failures. In real operation, the lifetime of the tube can be significantly reduced because of failures. The special fast protection klystron lifetime management (KLM) system has been developed to minimize the influence of service conditions on the lifetime of klystrons. The main task of this system is to detect all events which can destroy the tube as quickly as possible, and switch off the driving RF signal or the high voltage. Detection of events is based on a comparison of the value of the real signal obtained at the system output with the value estimated on the basis of a high-power RF amplifier model and input signals. The KLM system has been realized in field-programmable gate array (FPGA) and implemented in XFEL. Implementation is based on the standard low-level RF micro telecommunications computing architecture (MTCA.4 or xTCA). The main part of the paper focuses on an estimation of the klystron model and the implementation of KLM in FPGA. The results of the performance of the KLM system will also be presented.

Bioengineered riboflavin in nanotechnology.

PubMed

Beztsinna, N; Solé, M; Taib, N; Bestel, I

2016-02-01

Riboflavin (RF) is an essential water-soluble vitamin with unique biological and physicochemical properties such as transporterspecific cell internalization, implication in redox reactions, fluorescence and photosensitizing. Due to these features RF attracted researchers in various fields from targeted drug delivery and tissue engineering to optoelectronics and biosensors. In this review we will give a brief reminder of RF chemistry, its optical, photosensitizing properties, RF transporter systems and its role in pathologies. We will point a special attention on the recent findings concerning RF applications in nanotechnologies such as RF functionalized nanoparticles, polymers, biomolecules, carbon nanotubes, hydrogels and implants for tissue engineering. Copyright © 2015 Elsevier Ltd. All rights reserved.

Spacecraft-level verification of the Van Allen Probes' RF communication system

NASA Astrophysics Data System (ADS)

Crowne, M. J.; Srinivasan, D.; Royster, D.; Weaver, G.; Matlin, D.; Mosavi, N.

This paper presents the verification process, lessons learned, and selected test results of the radio frequency (RF) communication system of the Van Allen Probes, formerly known as the Radiation Belt Storm Probes (RBSP). The Van Allen Probes mission is investigating the doughnut-shaped regions of space known as the Van Allen radiation belts where the Sun interacts with charged particles trapped in Earth's magnetic field. Understanding this dynamic area that surrounds our planet is important to improving our ability to design spacecraft and missions for reliability and astronaut safety. The Van Allen Probes mission features two nearly identical spacecraft designed, built, and operated by the Johns Hopkins University Applied Physics Laboratory (JHU/APL) for the National Aeronautics and Space Administration (NASA). The RF communication system features the JHU/APL Frontier Radio. The Frontier Radio is a software-defined radio (SDR) designed for spaceborne communications, navigation, radio science, and sensor applications. This mission marks the first spaceflight usage of the Frontier Radio. RF ground support equipment (RF GSE) was developed using a ground station receiver similar to what will be used in flight and whose capabilities provided clarity into RF system performance that was previously not obtained until compatibility testing with the ground segments. The Van Allen Probes underwent EMC, acoustic, vibration, and thermal vacuum testing at the environmental test facilities at APL. During this time the RF communication system was rigorously tested to ensure optimal performance, including system-level testing down to threshold power levels. Compatibility tests were performed with the JHU/APL Satellite Communication Facility (SCF), the Universal Space Network (USN), and the Tracking and Data Relay Satellite System (TDRSS). Successful completion of this program as described in this paper validated the design of the system and demonstrated that it will be able to me- t all of the Van Allen Probes's communications requirements with its intended ground segments.

Design and Implementation of RF Energy Harvesting System for Low-Power Electronic Devices

NASA Astrophysics Data System (ADS)

Uzun, Yunus

2016-08-01

Radio frequency (RF) energy harvester systems are a good alternative for energizing of low-power electronics devices. In this work, an RF energy harvester is presented to obtain energy from Global System for Mobile Communications (GSM) 900 MHz signals. The energy harvester, consisting of a two-stage Dickson voltage multiplier circuit and L-type impedance matching circuits, was designed, simulated, fabricated and tested experimentally in terms of its performance. Simulation and experimental works were carried out for various input power levels, load resistances and input frequencies. Both simulation and experimental works have been carried out for this frequency band. An efficiency of 45% is obtained from the system at 0 dBm input power level using the impedance matching circuit. This corresponds to the power of 450 μW and this value is sufficient for many low-power devices. The most important parameters affecting the efficiency of the RF energy harvester are the input power level, frequency band, impedance matching and voltage multiplier circuits, load resistance and the selection of diodes. RF energy harvester designs should be optimized in terms of these parameters.

Development progresses of radio frequency ion source for neutral beam injector in fusion devices.

PubMed

Chang, D H; Jeong, S H; Kim, T S; Park, M; Lee, K W; In, S R

2014-02-01

A large-area RF (radio frequency)-driven ion source is being developed in Germany for the heating and current drive of an ITER device. Negative hydrogen ion sources are the major components of neutral beam injection systems in future large-scale fusion experiments such as ITER and DEMO. RF ion sources for the production of positive hydrogen (deuterium) ions have been successfully developed for the neutral beam heating systems at IPP (Max-Planck-Institute for Plasma Physics) in Germany. The first long-pulse ion source has been developed successfully with a magnetic bucket plasma generator including a filament heating structure for the first NBI system of the KSTAR tokamak. There is a development plan for an RF ion source at KAERI to extract the positive ions, which can be applied for the KSTAR NBI system and to extract the negative ions for future fusion devices such as the Fusion Neutron Source and Korea-DEMO. The characteristics of RF-driven plasmas and the uniformity of the plasma parameters in the test-RF ion source were investigated initially using an electrostatic probe.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rowe, Nathan C; Younkin, James R; Pickett, Chris A

Radio-Frequency (RF) devices have revolutionized many aspects of modern industrial processes. RF technology can enable wireless communication for tag identification, sensor communication, and asset tracking. Radio-frequency identification (RFID) is a technology that utilizes wireless communication to interrogate and identify an electronic tag attached to an item in order to identify the item. The technology can come in many forms: passive or active tags, low to ultra-wideband frequencies, small paper-thin tags to brick-sized units, and simple tags or highly integrated sensor packages. RF technology, and specifically RFID, has been applied widely in commercial markets for inventory, supply chain management, and assetmore » tracking. Several recent studies have demonstrated the safeguards benefits of utilizing RFID versus conventional inventory tagging methods for tracking nuclear material. These studies have indicated that the RF requirements for safeguards functions are more stringent than the RF requirements for other inventory tracking and accounting applications. Additionally, other requirements must be addressed, including environmental and operating conditions, authentication, and tag location and attachment. Facility restrictions on radio spectrum, method of tag attachment, and sensitivity of the data collected impact the tag selection and system design. More important, the intended use of the system must be considered. The requirements for using RF to simply replace or supplement container identifiers such as bar codes that facilitate the inventory function will differ greatly from the requirements for deploying RF for unattended monitoring applications. Several studies have investigated these considerations to advance commercial RF devices for safeguards use, and a number of system concepts have been developed. This paper will provide an overview of past studies and current technologies, and will investigate the requirements, existing gaps, and several potential next steps for advancing RF techniques for safeguards use.« less

NLC Special Projects

Science.gov Websites

Measurement (with NLC RF group) LCLS and related technologies (LCLS work related to NLC work) Collimation Systems (with Beam Delivery group) Combined Laser System (with NLC sources group) Polarized Positron Sources (with NLC sources group) Crab Cavity Phase Control System Timing and RF distribution System (with

Observation of a Discrete Time Crystal

NASA Astrophysics Data System (ADS)

Kyprianidis, A.; Zhang, J.; Hess, P.; Becker, P.; Lee, A.; Smith, J.; Pagano, G.; Potter, A.; Vishwanath, A.; Potirniche, I.-D.; Yao, N.; Monroe, C.

2017-04-01

Spontaneous symmetry breaking is a key concept in the understanding of many physical phenomena, such as the formation of spatial crystals and the phase transition from paramagnetism to magnetic order. While the breaking of time translation symmetry is forbidden in equilibrium systems, it is possible for non-equilibrium Floquet driven systems to break a discrete time translation symmetry, and we present clear signatures of the formation of such a discrete time crystal. We apply a time periodic Hamiltonian to a chain of interacting spins under many-body localization conditions and observe the system's sub-harmonic response at twice that period. This spontaneous doubling of the periodicity is robust to external perturbations. We represent the spins with a linear chain of trapped 171Yb+ ions in an rf Paul trap, generate spin-spin interactions through spin-dependent optical dipole forces, and measure each spin using state-dependent fluorescence. This work is supported by the ARO Atomic Physics Program, the AFOSR MURI on Quantum Measurement and Verification, and the NSF Physics Frontier Center at JQI.

Advanced RF Front End Technology

NASA Technical Reports Server (NTRS)

Herman, M. I.; Valas, S.; Katehi, L. P. B.

2001-01-01

The ability to achieve low-mass low-cost micro/nanospacecraft for Deep Space exploration requires extensive miniaturization of all subsystems. The front end of the Telecommunication subsystem is an area in which major mass (factor of 10) and volume (factor of 100) reduction can be achieved via the development of new silicon based micromachined technology and devices. Major components that make up the front end include single-pole and double-throw switches, diplexer, and solid state power amplifier. JPL's Center For Space Microsystems - System On A Chip (SOAC) Program has addressed the challenges of front end miniaturization (switches and diplexers). Our objectives were to develop the main components that comprise a communication front end and enable integration in a single module that we refer to as a 'cube'. In this paper we will provide the latest status of our Microelectromechanical System (MEMS) switches and surface micromachined filter development. Based on the significant progress achieved we can begin to provide guidelines of the proper system insertion for these emerging technologies. Additional information is contained in the original extended abstract.

Local oscillator induced degradation of medium-term stability in passive atomic frequency standards

NASA Technical Reports Server (NTRS)

Dick, G. John; Prestage, John D.; Greenhall, Charles A.; Maleki, Lute

1990-01-01

As the performance of passive atomic frequency standards improves, a new limitation is encountered due to frequency fluctuations in an ancillary local oscillator (L.O.). The effect is due to time variation in the gain of the feedback which compensates L.O. frequency fluctuations. The high performance promised by new microwave and optical trapped ion standards may be severely compromised by this effect. Researchers present an analysis of this performance limitation for the case of sequentially interrogated standards. The time dependence of the sensitivity of the interrogation process to L.O. frequency fluctuations is evaluated for single-pulse and double-pulse Ramsey RF interrogation and for amplitude modulated pulses. The effect of these various time dependencies on performance of the standard is calculated for an L.O. with frequency fluctuations showing a typical 1/f spectral density. A limiting 1/sq. root gamma dependent deviation of frequency fluctuations is calculated as a function of pulse lengths, dead time, and pulse overlap. Researchers also present conceptual and hardware-oriented solutions to this problem which achieve a much more nearly constant sensitivity to L.O. fluctuations. Solutions involve use of double-pulse interrogation; alternate interrogation of multiple traps so that the dead time of one trap can be covered by operation of the other; and the use of double-pulse interrogation for two traps, so that during the time of the RF pulses, the increasing sensitivity of one trap tends to compensate for the decreasing sensitivity of the other. A solution making use of amplified-modulated pulses is also presented which shows nominally zero time variation.

UWB dual burst transmit driver

DOEpatents

Dallum, Gregory E [Livermore, CA; Pratt, Garth C [Discovery Bay, CA; Haugen, Peter C [Livermore, CA; Zumstein, James M [Livermore, CA; Vigars, Mark L [Livermore, CA; Romero, Carlos E [Livermore, CA

2012-04-17

A dual burst transmitter for ultra-wideband (UWB) communication systems generates a pair of precisely spaced RF bursts from a single trigger event. An input trigger pulse produces two oscillator trigger pulses, an initial pulse and a delayed pulse, in a dual trigger generator. The two oscillator trigger pulses drive a gated RF burst (power output) oscillator. A bias driver circuit gates the RF output oscillator on and off and sets the RF burst packet width. The bias driver also level shifts the drive signal to the level that is required for the RF output device.

Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

NASA Astrophysics Data System (ADS)

Brombin, M.; Spolaore, M.; Serianni, G.; Pomaro, N.; Taliercio, C.; Palma, M. Dalla; Pasqualotto, R.; Schiesko, L.

2014-11-01

A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors' holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.

Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from Radio Frequency plasma) experiment: tests in BATMAN (BAvarian Test Machine for Negative ions).

PubMed

Brombin, M; Spolaore, M; Serianni, G; Pomaro, N; Taliercio, C; Dalla Palma, M; Pasqualotto, R; Schiesko, L

2014-11-01

A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors' holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.

RF Guns for Generation of Polarized Electron Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clendenin, J.E.; Brachmann, A.; Dowell, D.H.

2005-11-09

Several accelerators, including the SLC, JLAB, Mainz, Bates/MIT, and Bonn have successfully operated for medium and high energy physics experiments using polarized electron beams generated by dc-biased guns employing GaAs photocathodes. Since these guns have all used a bias on the order of 100 kV, the longitudinal emittance of the extracted bunch is rather poor. Downstream rf bunching systems increase the transverse emittance. An rf gun with a GaAs photocathode would eliminate the need for separate rf bunchers, resulting in a simpler injection system. In addition, the thermal emittance of GaAs-type cathodes is significantly lower than for other photocathode materials.more » The environmental requirements for operating activated GaAs photocathodes cannot be met by rf guns as currently designed and operated. These requirements, including limits on vacuum and electron back bombardment, are discussed in some detail. Modifications to actual and proposed rf gun designs that would allow these requirements to be met are presented.« less

Ultra High-Speed Radio Frequency Switch Based on Photonics.

PubMed

Ge, Jia; Fok, Mable P

2015-11-26

Microwave switches, or Radio Frequency (RF) switches have been intensively used in microwave systems for signal routing. Compared with the fast development of microwave and wireless systems, RF switches have been underdeveloped particularly in terms of switching speed and operating bandwidth. In this paper, we propose a photonics based RF switch that is capable of switching at tens of picoseconds speed, which is hundreds of times faster than any existing RF switch technologies. The high-speed switching property is achieved with the use of a rapidly tunable microwave photonic filter with tens of gigahertz frequency tuning speed, where the tuning mechanism is based on the ultra-fast electro-optics Pockels effect. The RF switch has a wide operation bandwidth of 12 GHz and can go up to 40 GHz, depending on the bandwidth of the modulator used in the scheme. The proposed RF switch can either work as an ON/OFF switch or a two-channel switch, tens of picoseconds switching speed is experimentally observed for both type of switches.

Microfluidic stretchable RF electronics.

PubMed

Cheng, Shi; Wu, Zhigang

2010-12-07

Stretchable electronics is a revolutionary technology that will potentially create a world of radically different electronic devices and systems that open up an entirely new spectrum of possibilities. This article proposes a microfluidic based solution for stretchable radio frequency (RF) electronics, using hybrid integration of active circuits assembled on flex foils and liquid alloy passive structures embedded in elastic substrates, e.g. polydimethylsiloxane (PDMS). This concept was employed to implement a 900 MHz stretchable RF radiation sensor, consisting of a large area elastic antenna and a cluster of conventional rigid components for RF power detection. The integrated radiation sensor except the power supply was fully embedded in a thin elastomeric substrate. Good electrical performance of the standalone stretchable antenna as well as the RF power detection sub-module was verified by experiments. The sensor successfully detected the RF radiation over 5 m distance in the system demonstration. Experiments on two-dimensional (2D) stretching up to 15%, folding and twisting of the demonstrated sensor were also carried out. Despite the integrated device was severely deformed, no failure in RF radiation sensing was observed in the tests. This technique illuminates a promising route of realizing stretchable and foldable large area integrated RF electronics that are of great interest to a variety of applications like wearable computing, health monitoring, medical diagnostics, and curvilinear electronics.

500-Watt Solid-State RF Power Amplifier AM-7209( )/VRC.

DTIC Science & Technology

1983-03-18

AD-A127 462 580-WRATT SOLID-STATE RF POWER AMPLIFIER AM-7289( )/VRC 1/2 (U) E- SYSTEMS INC ST PETERSBURG FL ECI DIV N HARRIS 18 MAR 83 60-6±289 CECOM...AND DEVELOPMENT TECHNICAL REPORT CECOM-82-C-J23 1 500-WATT SOLID-STATE RF POWER AMPLIFIER AM-7209( )/VRC M. Harris E- SYSTEMS , INC., ECI DIVISION 1502...CONTRACT OR GRANT NUMSER(t) M. Harris DAABO7-82-C-J231 9m PERFORMING ORGANIZATION NAME AND ADDRESS II. PROGRAM ELEMENT. PROJECT TASK E- SYSTEMS , INC

Scaling of Multimillion-Atom Biological Molecular Dynamics Simulation on a Petascale Supercomputer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schulz, Roland; Lindner, Benjamin; Petridis, Loukas

2009-01-01

A strategy is described for a fast all-atom molecular dynamics simulation of multimillion-atom biological systems on massively parallel supercomputers. The strategy is developed using benchmark systems of particular interest to bioenergy research, comprising models of cellulose and lignocellulosic biomass in an aqueous solution. The approach involves using the reaction field (RF) method for the computation of long-range electrostatic interactions, which permits efficient scaling on many thousands of cores. Although the range of applicability of the RF method for biomolecular systems remains to be demonstrated, for the benchmark systems the use of the RF produces molecular dipole moments, Kirkwood G factors,more » other structural properties, and mean-square fluctuations in excellent agreement with those obtained with the commonly used Particle Mesh Ewald method. With RF, three million- and five million atom biological systems scale well up to 30k cores, producing 30 ns/day. Atomistic simulations of very large systems for time scales approaching the microsecond would, therefore, appear now to be within reach.« less

Scaling of Multimillion-Atom Biological Molecular Dynamics Simulation on a Petascale Supercomputer.

PubMed

Schulz, Roland; Lindner, Benjamin; Petridis, Loukas; Smith, Jeremy C

2009-10-13

A strategy is described for a fast all-atom molecular dynamics simulation of multimillion-atom biological systems on massively parallel supercomputers. The strategy is developed using benchmark systems of particular interest to bioenergy research, comprising models of cellulose and lignocellulosic biomass in an aqueous solution. The approach involves using the reaction field (RF) method for the computation of long-range electrostatic interactions, which permits efficient scaling on many thousands of cores. Although the range of applicability of the RF method for biomolecular systems remains to be demonstrated, for the benchmark systems the use of the RF produces molecular dipole moments, Kirkwood G factors, other structural properties, and mean-square fluctuations in excellent agreement with those obtained with the commonly used Particle Mesh Ewald method. With RF, three million- and five million-atom biological systems scale well up to ∼30k cores, producing ∼30 ns/day. Atomistic simulations of very large systems for time scales approaching the microsecond would, therefore, appear now to be within reach.

Toward high fidelity spectral sensing and RF signal processing in silicon photonic and nano-opto-mechanical platforms

NASA Astrophysics Data System (ADS)

Siddiqui, Aleem; Reinke, Charles; Shin, Heedeuk; Jarecki, Robert L.; Starbuck, Andrew L.; Rakich, Peter

2017-05-01

The performance of electronic systems for radio-frequency (RF) spectrum analysis is critical for agile radar and communications systems, ISR (intelligence, surveillance, and reconnaissance) operations in challenging electromagnetic (EM) environments, and EM-environment situational awareness. While considerable progress has been made in size, weight, and power (SWaP) and performance metrics in conventional RF technology platforms, fundamental limits make continued improvements increasingly difficult. Alternatively, we propose employing cascaded transduction processes in a chip-scale nano-optomechanical system (NOMS) to achieve a spectral sensor with exceptional signal-linearity, high dynamic range, narrow spectral resolution and ultra-fast sweep times. By leveraging the optimal capabilities of photons and phonons, the system we pursue in this work has performance metrics scalable well beyond the fundamental limitations inherent to all electronic systems. In our device architecture, information processing is performed on wide-bandwidth RF-modulated optical signals by photon-mediated phononic transduction of the modulation to the acoustical-domain for narrow-band filtering, and then back to the optical-domain by phonon-mediated phase modulation (the reverse process). Here, we rely on photonics to efficiently distribute signals for parallel processing, and on phononics for effective and flexible RF-frequency manipulation. This technology is used to create RF-filters that are insensitive to the optical wavelength, with wide center frequency bandwidth selectivity (1-100GHz), ultra-narrow filter bandwidth (1-100MHz), and high dynamic range (70dB), which we will present. Additionally, using this filter as a building block, we will discuss current results and progress toward demonstrating a multichannel-filter with a bandwidth of < 10MHz per channel, while minimizing cumulative optical/acoustic/optical transduced insertion-loss to ideally < 10dB. These proposed metric represent significant improvements over RF-platforms.

Study of RF breakdown and multipacting in accelerator components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pande, Manjiri; Singh, P., E-mail: manjiri@barc.gov.in, E-mail: psingh@barc.gov.in

2014-07-01

Radio frequency (RF) structures that are part of accelerators and energy sources, operate with sinusoidally varying electromagnetic fields under high RF energy. Here, RF breakdown and multipacting take place in RF structures and limit their performance. Electron field emission processes in a RF structure are precursors for breakdown processes. RF breakdown is a major phenomena affecting and causing the irreversible damage to RF structures. Breakdown rate and the damage induced by the breakdowns are its important properties. The damage is related to power absorbed during breakdown, while the breakdown rate is determined by the amplitudes of surface electric and magneticmore » fields, geometry, metal surface preparation and conditioning history. It limits working power and produces irreversible surface damage. The breakdown limit depends on the RF circuit, structure geometry, RF frequency, input RF power, pulse width, materials used, surface processing technique and surface electric and magnetic fields. Multipactor (MP) is a low power, electron multiplication based resonance breakdown phenomenon in vacuum and is often observed in RF structures. A multipactor discharge is undesirable, as it can create a reactive component that detunes the resonant cavities and components, generates noise in communication system and induces gas desorption from the conductor surfaces. In RF structures, certain conditions are required to generate multipacting. (author)« less

Development and testing of a double length pets for the CLIC experimental area

NASA Astrophysics Data System (ADS)

Sánchez, L.; Carrillo, D.; Gavela, D.; Lara, A.; Rodríguez, E.; Gutiérrez, J. L.; Calero, J.; Toral, F.; Samoshkin, A.; Gudkov, D.; Riddone, G.

2014-05-01

CLIC (compact linear collider) is a future e+e- collider based on normal-conducting technology, currently under study at CERN. Its design is based on a novel two-beam acceleration scheme. The main beam gets RF power extracted from a drive beam through power extraction and transfer structures (PETS). The technical feasibility of CLIC is currently being proved by its Third Test Facility (CTF3) which includes the CLIC experimental area (CLEX). Two Double Length CLIC PETS will be installed in CLEX to validate their performance with beam. This paper is focused on the engineering design, fabrication and validation of this PETS first prototype. The design consists of eight identical bars, separated by radial slots in which damping material is located to absorb transverse wakefields, and two compact couplers placed at both ends of the bars to extract the generated power. The PETS bars are housed inside a vacuum tank designed to make the PETS as compact as possible. Several joint techniques such as vacuum brazing, electron beam and arc welding were used to complete the assembly. Finally, several tests such as dimensional control and leak testing were carried out to validate design and fabrication methods. In addition, RF measurements at low power were made to study frequency tuning.

Exploring channeling optimized radiofrequency energy: a review of radiofrequency history and applications in esthetic fields.

PubMed

Belenky, Inna; Margulis, Ariel; Elman, Monica; Bar-Yosef, Udi; Paun, Silviu D

2012-03-01

Because of its high efficiency and safety, radiofrequency (RF) energy is widely used in the dermatological field for heating biological tissue in various esthetic applications, including skin tightening, skin lifting, body contouring, and cellulite reduction. This paper reviews the literature on the use of nonablative RF energy in the esthetic field and its scientific background. The purpose of this article is to describe in detail the extensive use of medical devices based on RF technology, the development of these medical devices over the years, and recent developments and trends in RF technology. The authors conducted a systematic search of publications that address safety and efficacy issues, technical system specifications, and clinical techniques. Finally, the authors focused on their own clinical experiences with the use of patented Channeling Optimized RF Energy technique and mechanical massage. An in-vivo study was conducted in domestic pigs, with a thermal video camera. Twenty-seven female patients participated in a cellulite and body shaping study. The treatments were conducted according to a three-phase protocol. An additional 16 females participated in a skin tightening case study. All of the patients underwent three treatment sessions at 3-week intervals, each according to a protocol specific to the area being treated. The review of the literature on RF-based systems revealed that these systems are safe, with low risks for potential side effects, and effective for cellulite, body contouring, and skin tightening procedures. The in-vivo measurements confirmed the theory that the penetration depth of RF is an inverse function of its frequency, and using a vacuum mechanism makes an additional contribution to the RF energy penetration. The heating effect of RF was also found to increase blood circulation and to induce collagen remodeling. The results from the cellulite and body shaping treatments showed an overall average improvement of 55% in the appearance of cellulite, with an average circumferential reduction of 3.31 cm in the buttocks, 2.94 cm in the thighs, and 2.14 cm in the abdomen. The results from the skin tightening procedure showed moderate improvement of skin appearance in 50% and significant improvement in 31%. At the follow-up visits the results were found to be sustained without any significant side effects. Of all tissue heating techniques, RF-based technologies appear to be the most established and clinically proven. The design and specifications of the described vacuumassisted bipolar RF device fall within the range of the specifications currently prescribed for esthetic, nonablative RF systems.

Thermal and dynamic range characterization of a photonics-based RF amplifier

NASA Astrophysics Data System (ADS)

Noque, D. F.; Borges, R. M.; Muniz, A. L. M.; Bogoni, A.; Cerqueira S., Arismar, Jr.

2018-05-01

This work reports a thermal and dynamic range characterization of an ultra-wideband photonics-based RF amplifier for microwave and mm-waves future 5G optical-wireless networks. The proposed technology applies the four-wave mixing nonlinear effect to provide RF amplification in analog and digital radio-over-fiber systems. The experimental analysis from 300 kHz to 50 GHz takes into account different figures of merit, such as RF gain, spurious-free dynamic range and RF output power stability as a function of temperature. The thermal characterization from -10 to +70 °C demonstrates a 27 dB flat photonics-assisted RF gain over the entire frequency range under real operational conditions of a base station for illustrating the feasibility of the photonics-assisted RF amplifier for 5G networks.

Effects of long-term fertilization practices on heavy metal cadmium accumulation in the surface soil and rice plants of double-cropping rice system in Southern China.

PubMed

Xu, Yilan; Tang, Haiming; Liu, Tangxing; Li, Yifeng; Huang, Xinjie; Pi, Jun

2018-05-08

Fertilizer regime is playing an important role in heavy metal cadmium (Cd) accumulation in paddy soils and crop plant. It is necessary to assess the Cd accumulation in soils and rice (Oryza sativa L.) plants under long-term fertilization managements, and the results which help to assess the environmental and food risk in Southern China. However, the effects of different organic manure and chemical fertilizers on Cd accumulation in soils and rice plant remain unclear under intensively cultivated rice conditions. Therefore, the objective was to explore Cd accumulation in paddy soils and rice plant at mature stage under different long-term fertilization managements in the double-cropping rice system. Cd accumulation in the surface soils (0-20 cm) and rice plant with chemical fertilizer alone (MF), rice straw residue and chemical fertilizer (RF), 30% organic matter and 70% chemical fertilizer (LOM), 60% organic matter and 40% chemical fertilizer (HOM), and without fertilizer input (CK) basis on 32 years long-term fertilization experiment were analyzed. The results showed that the soil total Cd content was increased by 0.296 and 0.351 mg kg -1 and 0.261 and 0.340 mg kg -1 under LOM and HOM treatments at early and late rice mature stages, respectively, compared with the CK treatment. And the soil available Cd content was increased by 0.073 and 0.137 mg kg -1 and 0.102 and 0.160 mg kg -1 under LOM and HOM treatments at early and late rice mature stages, respectively, compared with the CK treatment. The bioconcentration factor of Cd across different parts of rice plant was the highest in root, followed by stem and grain, and the lowest in leaves. At early and late rice mature stages, the root Cd concentration of rice plant was increased by 0.689 and 0.608 mg kg -1 with HOM treatment, the stem Cd concentration of rice plant was increased by 0.666 and 0.758 mg kg -1 with RF treatment, and the leaf and grain Cd concentration of rice plant was increased 0.094 and 0.082 mg kg -1 and 0.086 and 0.083 mg kg -1 with LOM treatment, respectively, compared with the CK treatment. The soil Cd single-factor contaminant index (P Cd ) under different fertilization treatments was as the following HOM > LOM > RF > MF > CK. Meanwhile, the P Cd with LOM and HOM treatments was higher than that of the MF, RF, and CK treatments, but there is no significant difference between that of MF and RF treatments. Therefore, long-term application of rice straw residue and chemical fertilizer had no obvious effect on the accumulation of Cd in paddy soils and grain, and soil Cd accumulation was increased as application of organic fertilizer.

SITE project. Phase 1: Continuous data bit-error-rate testing

NASA Technical Reports Server (NTRS)

Fujikawa, Gene; Kerczewski, Robert J.

1992-01-01

The Systems Integration, Test, and Evaluation (SITE) Project at NASA LeRC encompasses a number of research and technology areas of satellite communications systems. Phase 1 of this project established a complete satellite link simulator system. The evaluation of proof-of-concept microwave devices, radiofrequency (RF) and bit-error-rate (BER) testing of hardware, testing of remote airlinks, and other tests were performed as part of this first testing phase. This final report covers the test results produced in phase 1 of the SITE Project. The data presented include 20-GHz high-power-amplifier testing, 30-GHz low-noise-receiver testing, amplitude equalization, transponder baseline testing, switch matrix tests, and continuous-wave and modulated interference tests. The report also presents the methods used to measure the RF and BER performance of the complete system. Correlations of the RF and BER data are summarized to note the effects of the RF responses on the BER.

A novel photonic oscillator

NASA Technical Reports Server (NTRS)

Yao, X. S.; Maleki, L.

1995-01-01

We report a novel oscillator for photonic RF systems. This oscillator is capable of generating high-frequency signals up to 70 GHz in both electrical and optical domains and is a special voltage-controlled oscillator with an optical output port. It can be used to make a phase-locked loop (PLL) and perform all functions that a PLL is capable of for photonic systems. It can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and PLL. It can also be self-phase locked and self-injection locked to generate a high-stability photonic RF reference. Its applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb-frequecy and square-wave generation, carrier recovery, and clock recovery. We anticipate that such photonic voltage-controlled oscillators (VCOs) will be as important to photonic RF systems as electrical VCOs are to electrical RF systems.

Two non-allelic nuclear genes restore fertility in a gametophytic pattern and enhance abiotic stress tolerance in the hybrid rice plant.

PubMed

Huang, Wenchao; Hu, Jun; Yu, Changchun; Huang, Qi; Wan, Lei; Wang, Lili; Qin, Xiaojian; Ji, Yanxiao; Zhu, Renshan; Li, Shaoqing; Zhu, Yingguo

2012-03-01

In indica rice, the HongLian (HL)-type combination of cytoplasmic male sterility (CMS) and fertility restoration (Rf) is widely used for the production of commercial hybrid seeds in China, Laos, Vietnam and other Southeast Asian countries. Generally, any member of the gametophytic fertility restoration system, 50% of the pollen in hybrid F(1) plants displays recovered sterility. In this study, however, a HL-type hybrid variety named HongLian You6 had approximately 75% normal (viable) pollen rather than the expected 50%. To resolve this discrepancy, several fertility segregation populations, including F(2) and BC(1)F(1) derived from the HL-CMS line Yuetai A crossed with the restorer line 9311, were constructed and subjected to genetic analysis. A gametophytic restoration model was discovered to involve two non-allelic nuclear restorer genes, Rf5 and Rf6. The Rf5 had been previously identified using a positional clone strategy. The Rf6 gene represents a new restorer gene locus, which was mapped to the short arm of chromosome 8. The hybrid F(1) plants containing one restorer gene, either Rf5 or Rf6, displayed 50% normal pollen grains with I(2)-KI solution; however, those with both Rf5 and Rf6 displayed 75% normal pollens. We also established that the hybrid F(1) plants including both non-allelic restorer genes exhibited an increased stable seed setting when subjected to stress versus the F(1) plants with only one restorer gene. Finally, we discuss the breeding scheme for the plant gametophytic CMS/Rf system.

Planting Patterns and Deficit Irrigation Strategies to Improve Wheat Production and Water Use Efficiency under Simulated Rainfall Conditions

PubMed Central

Ali, Shahzad; Xu, Yueyue; Ma, Xiangcheng; Ahmad, Irshad; Kamran, Muhammad; Dong, Zhaoyun; Cai, Tie; Jia, Qianmin; Ren, Xiaolong; Zhang, Peng; Jia, Zhikuan

2017-01-01

The ridge furrow (RF) rainwater harvesting system is an efficient way to enhance rainwater accessibility for crops and increase winter wheat productivity in semi-arid regions. However, the RF system has not been promoted widely in the semi-arid regions, which primarily exist in remote hilly areas. To exploit its efficiency on a large-scale, the RF system needs to be tested at different amounts of simulated precipitation combined with deficit irrigation. Therefore, in during the 2015–16 and 2016–17 winter wheat growing seasons, we examined the effects of two planting patterns: (1) the RF system and (2) traditional flat planting (TF) with three deficit irrigation levels (150, 75, 0 mm) under three simulated rainfall intensity (1: 275, 2: 200, 3: 125 mm), and determined soil water storage profile, evapotranspiration rate, grain filling rate, biomass, grain yield, and net economic return. Over the two study years, the RF treatment with 200 mm simulated rainfall and 150 mm deficit irrigation (RF2150) significantly (P < 0.05) increased soil water storage in the depth of (200 cm); reduced ET at the field scale by 33%; increased total dry matter accumulation per plant; increased the grain-filling rate; and improved biomass (11%) and grain (19%) yields. The RF2150 treatment thus achieved a higher WUE (76%) and RIWP (21%) compared to TF. Grain-filling rates, grain weight of superior and inferior grains, and net economic profit of winter wheat responded positively to simulated rainfall and deficit irrigation under both planting patterns. The 200 mm simulated rainfall amount was more economical than other precipitation amounts, and led to slight increases in soil water storage, total dry matter per plant, and grain yield; there were no significant differences when the simulated rainfall was increased beyond 200 mm. The highest (12,593 Yuan ha−1) net income profit was attained using the RF system at 200 mm rainfall and 150 mm deficit irrigation, which also led to significantly higher grain yield, WUE, and RIWP than all other treatments. Thus, we recommend the RF2150 treatment for higher productivity, income profit, and improve WUE in the dry-land farming system of China. PMID:28878787

Surface shapes and surrounding environment analysis of single- and double-stranded DNA-binding proteins in protein-DNA interface.

PubMed

Wang, Wei; Liu, Juan; Sun, Lin

2016-07-01

Protein-DNA bindings are critical to many biological processes. However, the structural mechanisms underlying these interactions are not fully understood. Here, we analyzed the residues shape (peak, flat, or valley) and the surrounding environment of double-stranded DNA-binding proteins (DSBs) and single-stranded DNA-binding proteins (SSBs) in protein-DNA interfaces. In the results, we found that the interface shapes, hydrogen bonds, and the surrounding environment present significant differences between the two kinds of proteins. Built on the investigation results, we constructed a random forest (RF) classifier to distinguish DSBs and SSBs with satisfying performance. In conclusion, we present a novel methodology to characterize protein interfaces, which will deepen our understanding of the specificity of proteins binding to ssDNA (single-stranded DNA) or dsDNA (double-stranded DNA). Proteins 2016; 84:979-989. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Standard/Handbook for RF Ionization Breakdown Prevention in Spacecraft Components

DTIC Science & Technology

2015-06-19

localized glow discharge of the plasma ( corona ) while RF power is being applied. 8.4.3 RF Performance Changes If a breakdown occurs and damages the...in spacecraft components and systems. Ionization breakdown is a high-energy radio frequency (RF) discharge that can occur when the insulating media...energy can be discharged in a small volume, releasing large amounts of heat, melting local surfaces, and generating debris, all of which will likely

Standard/Handbook for RF Ionization Breakdown Prevention in Spacecraft Components

DTIC Science & Technology

2015-06-19

localized glow discharge of the plasma ( corona ) while RF power is being applied. 8.4.3 RF Performance Changes If a breakdown occurs and damages the part...in spacecraft components and systems. Ionization breakdown is a high-energy radio frequency (RF) discharge that can occur when the insulating media...energy can be discharged in a small volume, releasing large amounts of heat, melting local surfaces, and generating debris, all of which will likely

Investigation of the RF efficiency of inductively coupled hydrogen plasmas at 1 MHz

NASA Astrophysics Data System (ADS)

Rauner, D.; Mattei, S.; Briefi, S.; Fantz, U.; Hatayama, A.; Lettry, J.; Nishida, K.; Tran, M. Q.

2017-08-01

The power requirements of RF heated sources for negative hydrogen ions in fusion are substantial, which poses strong demands on the generators and components of the RF circuit. Consequently, an increase of the RF coupling efficiency would be highly beneficial. Fundamental investigations of the RF efficiency in inductively coupled hydrogen and deuterium discharges in cylindrical symmetry are conducted at the lab experiment CHARLIE. The experiment is equipped with several diagnostics including optical emission spectroscopy and a movable floating double probe to monitor the plasma parameters. The presented investigations are performed in hydrogen at a varying pressure between 0.3 and 10 Pa, utilizing a conventional helical ICP coil driven at a frequency of 1 MHz and a fixed power of 520 W for plasma generation. The coupling efficiency is strongly affected by the variation in pressure, reaching up to 85 % between 1 and 3 Pa while dropping down to only 50 % at 0.3 Pa, which is the relevant operating pressure for negative hydrogen ion sources for fusion. Due to the lower power coupling, also the measured electron density at 0.3 Pa is only 5 . 1016 m-3, while it reaches up to 2.5 . 1017 m-3 with increasing coupling efficiency. In order to gain information on the spatially resolved aspects of RF coupling and plasma heating which are not diagnostically accessible, first simulations of the discharge by an electromagnetic Particle-In-Cell Monte Carlo collision method have been conducted and are compared to the measurement data. At 1 Pa, the simulated data corresponds well to the results of both axially resolved probe measurements and radially resolved emission profiles obtained via OES. Thereby, information regarding the radial distribution of the electron density and mean energy is provided, revealing a radial distribution of the electron density which is well described by a Bessel profile.

Improvements in Technique of NMR Imaging and NMR Diffusion Measurements in the Presence of Background Gradients.

NASA Astrophysics Data System (ADS)

Lian, Jianyu

In this work, modification of the cosine current distribution rf coil, PCOS, has been introduced and tested. The coil produces a very homogeneous rf magnetic field, and it is inexpensive to build and easy to tune for multiple resonance frequency. The geometrical parameters of the coil are optimized to produce the most homogeneous rf field over a large volume. To avoid rf field distortion when the coil length is comparable to a quarter wavelength, a parallel PCOS coil is proposed and discussed. For testing rf coils and correcting B _1 in NMR experiments, a simple, rugged and accurate NMR rf field mapping technique has been developed. The method has been tested and used in 1D, 2D, 3D and in vivo rf mapping experiments. The method has been proven to be very useful in the design of rf coils. To preserve the linear relation between rf output applied on an rf coil and modulating input for an rf modulating -amplifying system of NMR imaging spectrometer, a quadrature feedback loop is employed in an rf modulator with two orthogonal rf channels to correct the amplitude and phase non-linearities caused by the rf components in the rf system. The modulator is very linear over a large range and it can generate an arbitrary rf shape. A diffusion imaging sequence has been developed for measuring and imaging diffusion in the presence of background gradients. Cross terms between the diffusion sensitizing gradients and background gradients or imaging gradients can complicate diffusion measurement and make the interpretation of NMR diffusion data ambiguous, but these have been eliminated in this method. Further, the background gradients has been measured and imaged. A dipole random distribution model has been established to study background magnetic fields Delta B and background magnetic gradients G_0 produced by small particles in a sample when it is in a B_0 field. From this model, the minimum distance that a spin can approach a particle can be determined by measuring and <{bf G}_sp{0 }{2}>. From this model, the particle concentration in a sample can be determined by measuring the lineshape of a free induction decay (fid).

A high capacity data centre network: simultaneous 4-PAM data at 20 Gbps and 2 GHz phase modulated RF clock signal over a single VCSEL carrier

NASA Astrophysics Data System (ADS)

Isoe, G. M.; Wassin, S.; Gamatham, R. R. G.; Leitch, A. W. R.; Gibbon, T. B.

2017-11-01

Optical fibre communication technologies are playing important roles in data centre networks (DCNs). Techniques for increasing capacity and flexibility for the inter-rack/pod communications in data centres have drawn remarkable attention in recent years. In this work, we propose a low complexity, reliable, alternative technique for increasing DCN capacity and flexibility through multi-signal modulation onto a single mode VCSEL carrier. A 20 Gbps 4-PAM data signal is directly modulated on a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm, therefore, doubling the network bit rate. Carrier spectral efficiency is further maximized by modulating its phase attribute with a 2 GHz reference frequency (RF) clock signal. We, therefore, simultaneously transmit a 20 Gbps 4-PAM data signal and a phase modulated 2 GHz RF signal using a single mode 10 GHz bandwidth VCSEL carrier. It is the first time a single mode 10 GHz bandwidth VCSEL carrier is reported to simultaneously transmit a directly modulated 4-PAM data signal and a phase modulated RF clock signal. A receiver sensitivity of -10. 52 dBm was attained for a 20 Gbps 4-PAM VCSEL transmission. The 2 GHz phase modulated RF clock signal introduced a power budget penalty of 0.21 dB. Simultaneous distribution of both data and timing signals over shared infrastructure significantly increases the aggregated data rate at different optical network units within the DCN, without expensive optics investment. We further demonstrate on the design of a software-defined digital signal processing assisted receiver to efficiently recover the transmitted signal without employing costly receiver hardware.

Systems Analysis of Alternative Architectures for Riverine Warfare in 2010

DTIC Science & Technology

2006-12-01

propose system of systems improvements for the RF in 2010. With the RF currently working to establish a command structure, train and equip its forces...opposing force. Measures of performance such as time to first enemy detection and loss exchange ratio were collected from MANA. A detailed statistical

Efficient Direct-Matching Rectenna Design for RF Power Transfer Applications

NASA Astrophysics Data System (ADS)

Keyrouz, Shady; Visser, Huib

2013-12-01

This paper presents the design, simulation, fabrication and measurements of a 50 ohm rectenna system. The paper investigates each part (in terms of input impedance) of the rectenna system starting from the antenna, followed by the matching network, to the rectifier. The system consists of an antenna, which captures the transmitted RF signal, connected to a rectifier which converts the AC captured signal into a DC power signal. For maximum power transfer, a matching network is designed between the rectifier and the antenna. At an input power level of -10 dBm, the system is able to achieve an RF/DC power conversion efficiency of 49.7%.

VLF Radio Field Strength Measurement of power line carrier system in San Diego, California

NASA Technical Reports Server (NTRS)

Mertel, H. K.

1981-01-01

The radio frequency interference (RFI) potential was evaluated for a Powerline Carriet (PLC) installed in San Diego which monitors the performance of an electrical power system. The PLC system generated 30 amperes at 5.79 kHz. The RF radiations were measured to be (typically) 120 dBuV/m at the beginning of the 12 kV powerline and 60 dBuV/m at the end of the powerline. The RF fields varied inversely as the distance squared. Measurements were also performed with a 45 kHz PLC system. The RF fields were of similar amplitude.

Painless, safe, and efficacious noninvasive skin tightening, body contouring, and cellulite reduction using multisource 3DEEP radiofrequency.

PubMed

Harth, Yoram

2015-03-01

In the last decade, Radiofrequency (RF) energy has proven to be safe and highly efficacious for face and neck skin tightening, body contouring, and cellulite reduction. In contrast to first-generation Monopolar/Bipolar and "X -Polar" RF systems which use one RF generator connected to one or more skin electrodes, multisource radiofrequency devices use six independent RF generators allowing efficient dermal heating to 52-55°C, with no pain or risk of other side effects. In this review, the basic science and clinical results of body contouring and cellulite treatment using multisource radiofrequency system (Endymed PRO, Endymed, Cesarea, Israel) will be discussed and analyzed. © 2015 Wiley Periodicals, Inc.

Shuttle STS-2 mission communication systems RF coverage and performance predictions. Volume 1: Ascent

NASA Technical Reports Server (NTRS)

Porter, J. A.; Gibson, J. S.; Kroll, Q. D.; Loh, Y. C.

1981-01-01

The RF communications capabilities and nominally expected performance for the ascent phase of the second orbital flight of the shuttle are provided. Predicted performance is given mainly in the form of plots of signal strength versus elapsed mission time for the STDN (downlink) and shuttle orbiter (uplink) receivers for the S-band PM and FM, and UHF systems. Performance of the NAV and landing RF systems is treated for RTLS abort, since in this case the spacecraft will loop around and return to the launch site. NAV and landing RF systems include TACAN, MSBLS, and C-band altimeter. Signal strength plots were produced by a computer program which combines the spacecraft trajectory, antenna patterns, transmit and receive performance characteristics, and system mathematical models. When available, measured spacecraft parameters were used in the predictions; otherwise, specified values were used. Specified ground station parameter values were also used. Thresholds and other criteria on the graphs are explained.

RF Coupling into the Fuel Tank of a Large Transport Aircraft from Intentionally Transmitting Peds in the Passenger Cabin

NASA Technical Reports Server (NTRS)

Nguyen, Truong X.; Dudley, Kenneth L.; Scearce, Stephen A.; Ely, Jay J.; Richardson, Robert E.; Hatfield, Michael O.

2000-01-01

An investigation was performed to study the potential for radio frequency (RF) power radiated from Portable Electronic Devices (PEDs) to create an arcing/sparking event within the fuel tank of a large transport aircraft. This paper describes the experimental methods used for measuring RF coupling to the fuel tank and Fuel Quantity Indication System (FQIS) wiring from PED sources located in the passenger cabin. To allow comparison of voltage/current data obtained in a laboratory chamber FQIS installation to an actual aircraft FQIS installation, aircraft fuel tank RF reverberation characteristics were also measured. Results from the measurements, along with a survey of threats from typical intentional transmitting PEDs are presented. The resulting worst-case power coupled onto fuel tank FQIS wiring is derived. The same approach can be applied to measure RF coupling into various other aircraft systems.

Study of Pulsed vs. RF Plasma Properties for Surface Processing Applications

NASA Astrophysics Data System (ADS)

Tang, Ricky; Hopkins, Matthew; Barnat, Edward; Miller, Paul

2015-09-01

The ability to manipulate the plasma parameters (density, E/N) was previously demonstrated using a double-pulsed column discharge. Experiments extending this to large-surface plasmas of interest to the plasma processing community were conducted. Differences between an audio-frequency pulsed plasma and a radio-frequency (rf) discharge, both prevalent in plasma processing applications, were studied. Optical emission spectroscopy shows higher-intensity emission in the UV/visible range for the pulsed plasma comparing to the rf plasma at comparable powers. Data suggest that the electron energy is higher for the pulsed plasma leading to higher ionization, resulting in increased ion density and ion flux. Diode laser absorption measurements of the concentration of the 1S5 metastable and 1S4 resonance states of argon (correlated with the plasma E/N) provide comparisons between the excitation/ionization states of the two plasmas. Preliminary modeling efforts suggest that the low-frequency polarity switch causes a much more abrupt potential variation to support interesting transport phenomena, generating a ``wave'' of higher temperature electrons leading to more ionization, as well as ``sheath capture'' of a higher density bolus of ions that are then accelerated during polarity switch.

Low temperature RF plasma nitriding of self-organized TiO2 nanotubes for effective bandgap reduction

NASA Astrophysics Data System (ADS)

Bonelli, Thiago Scremin; Pereyra, Inés

2018-06-01

Titanium dioxide is a widely studied semiconductor material found in many nanostructured forms, presenting very interesting properties for several applications, particularly photocatalysis. TiO2 nanotubes have a high surface-to-volume ratio and functional electronic properties for light harvesting. Despite these manifold advantages, TiO2 photocatalytic activity is limited to UV radiation due to its large band gap. In this work, TiO2 nanotubes produced by electrochemical anodization were submitted to plasma nitriding processes in a PECVD reactor. The plasma parameters were evaluated to find the best conditions for gap reduction, in order to increase their photocatalytic activity. The pressure and RF power density were varied from 0.66 to 2.66 mbar and 0.22 to 3.51 W/cm2 respectively. The best gap reduction, to 2.80 eV, was achieved using a pressure of 1.33 mbar and 1.75 W/cm2 RF power at 320 °C, during a 2-h process. This leads to a 14% reduction in the band gap value and an increase of 25.3% in methylene blue reduction, doubling the range of solar photons absorption from 5 to 10% of the solar spectrum.

Acoustic Wave Filter Technology-A Review.

PubMed

Ruppel, Clemens C W

2017-09-01

Today, acoustic filters are the filter technology to meet the requirements with respect to performance dictated by the cellular phone standards and their form factor. Around two billion cellular phones are sold every year, and smart phones are of a very high percentage of approximately two-thirds. Smart phones require a very high number of filter functions ranging from the low double-digit range up to almost triple digit numbers in the near future. In the frequency range up to 1 GHz, surface acoustic wave (SAW) filters are almost exclusively employed, while in the higher frequency range, bulk acoustic wave (BAW) and SAW filters are competing for their shares. Prerequisites for the success of acoustic filters were the availability of high-quality substrates, advanced and highly reproducible fabrication technologies, optimum filter techniques, precise simulation software, and advanced design tools that allow the fast and efficient design according to customer specifications. This paper will try to focus on innovations leading to high volume applications of intermediate frequency (IF) and radio frequency (RF) acoustic filters, e.g., TV IF filters, IF filters for cellular phones, and SAW/BAW RF filters for the RF front-end of cellular phones.

Airborne characterization of smoke marker ratios from prescribed burning

NASA Astrophysics Data System (ADS)

Sullivan, A. P.; May, A. A.; Lee, T.; McMeeking, G. R.; Kreidenweis, S. M.; Akagi, S. K.; Yokelson, R. J.; Urbanski, S. P.; Collett, J. L., Jr.

2014-05-01

A Particle-into-Liquid Sampler - Total Organic Carbon and fraction collector system was flown aboard aTwin Otter aircraft sampling prescribed burning emissions in South Carolina in November2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated off-line samples for carbohydrate (i.e., smoke markers levoglucosan, mannosan, galactosan) analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Each fire location appeared to have aunique Δ levoglucosan / Δ water-soluble organic carbon (WSOC) ratio (RF01/RF02/RF03/RF05 = 0.163 ± 0.007 μg C μg C-1, RF08 = 0.115 ± 0.011 μg C μg C-1, RF09A = 0.072 ± 0.028 μg C μg C-1, RF09B = 0.042 ± 0.008 μg C μg C-1). These ratios were comparable to those obtained from controlled laboratory burns and suggested that the emissions sampled during RF01/RF02/RF03/RF05 were dominated by the burning of grasses, RF08 by leaves, RF09A by needles, and RF09B by marsh grasses. These findings were further supported by the Δ galactosan / Δ levoglucosan ratios (RF01/RF02/RF03/RF05 = 0.067 ± 0.004 μg μg-1, RF08 = 0.085 ± 0.009 μg μg-1, RF09A = 0.101 ± 0.029 μg μg-1) obtained as well as by the ground-based fuel and filter sample analyses during RF01/RF02/RF03/RF05. Differences between Δ potassium / Δ levoglucosan ratios obtained for these prescribed fires vs. laboratory-scale measurements suggest that some laboratory burns may not accurately represent potassium emissions from prescribed burns. The Δ levoglucosan / Δ WSOC ratio had no clear dependence on smoke age or fire dynamics suggesting that this ratio is more dependent on the type of fuel being burned. Levoglucosan was stable over a timescale of at least 1.5 h and could be useful to help estimate the air quality impacts of biomass burning.

The Hyper-X Antenna Radiation Pattern Tests and Radio Frequency System Redesign

NASA Technical Reports Server (NTRS)

Hodge, Mark W.; Kelley, John W.

2006-01-01

Testing was performed to determine the antenna radiation pattern measurements of the Hyper-X, X-43 ship 2 aircraft. One test was conducted at the Air Force Flight Test Center (AFFTC) Benefield Anechoic Facility (BAF) on January 24-January 27, 2000. A second test was done at MicroCraft in Tullahoma Tennessee by the Naval Air Weapons Center (NAWC) China Lake, California on September 8, 2001. The overall test objective was to gather qualitative antenna radiation pattern data from installed antennas on the HXRV. This objective was accomplished by collecting antenna radiation patterns at selected elevations of the HXRV. The test data was used to identify areas of RF coverage and assist in positioning the P-3 aircraft for best RF reception. The antenna pattern data presented nulls and possible low RF reception areas around the aircraft. This led to a redesign of the RF system. The redesigned system provided redundancy in case a telemetry transmitter should fail. The redesign provided more complete RF coverage within the antenna's capabilities. A second look at the flight path and necessary data collection led to a change in the beacon transponder system.

Spontaneous Magnetic Alignment by Yearling Snapping Turtles: Rapid Association of Radio Frequency Dependent Pattern of Magnetic Input with Novel Surroundings

PubMed Central

Landler, Lukas; Painter, Michael S.; Youmans, Paul W.; Hopkins, William A.; Phillips, John B.

2015-01-01

We investigated spontaneous magnetic alignment (SMA) by juvenile snapping turtles using exposure to low-level radio frequency (RF) fields at the Larmor frequency to help characterize the underlying sensory mechanism. Turtles, first introduced to the testing environment without the presence of RF aligned consistently towards magnetic north when subsequent magnetic testing conditions were also free of RF (‘RF off → RF off’), but were disoriented when subsequently exposed to RF (‘RF off → RF on’). In contrast, animals initially introduced to the testing environment with RF present were disoriented when tested without RF (‘RF on → RF off’), but aligned towards magnetic south when tested with RF (‘RF on → RF on’). Sensitivity of the SMA response of yearling turtles to RF is consistent with the involvement of a radical pair mechanism. Furthermore, the effect of RF appears to result from a change in the pattern of magnetic input, rather than elimination of magnetic input altogether, as proposed to explain similar effects in other systems/organisms. The findings show that turtles first exposed to a novel environment form a lasting association between the pattern of magnetic input and their surroundings. However, under natural conditions turtles would never experience a change in the pattern of magnetic input. Therefore, if turtles form a similar association of magnetic cues with the surroundings each time they encounter unfamiliar habitat, as seems likely, the same pattern of magnetic input would be associated with multiple sites/localities. This would be expected from a sensory input that functions as a global reference frame, helping to place multiple locales (i.e., multiple local landmark arrays) into register to form a global map of familiar space. PMID:25978736

Spontaneous magnetic alignment by yearling snapping turtles: rapid association of radio frequency dependent pattern of magnetic input with novel surroundings.

PubMed

Landler, Lukas; Painter, Michael S; Youmans, Paul W; Hopkins, William A; Phillips, John B

2015-01-01

We investigated spontaneous magnetic alignment (SMA) by juvenile snapping turtles using exposure to low-level radio frequency (RF) fields at the Larmor frequency to help characterize the underlying sensory mechanism. Turtles, first introduced to the testing environment without the presence of RF aligned consistently towards magnetic north when subsequent magnetic testing conditions were also free of RF ('RF off → RF off'), but were disoriented when subsequently exposed to RF ('RF off → RF on'). In contrast, animals initially introduced to the testing environment with RF present were disoriented when tested without RF ('RF on → RF off'), but aligned towards magnetic south when tested with RF ('RF on → RF on'). Sensitivity of the SMA response of yearling turtles to RF is consistent with the involvement of a radical pair mechanism. Furthermore, the effect of RF appears to result from a change in the pattern of magnetic input, rather than elimination of magnetic input altogether, as proposed to explain similar effects in other systems/organisms. The findings show that turtles first exposed to a novel environment form a lasting association between the pattern of magnetic input and their surroundings. However, under natural conditions turtles would never experience a change in the pattern of magnetic input. Therefore, if turtles form a similar association of magnetic cues with the surroundings each time they encounter unfamiliar habitat, as seems likely, the same pattern of magnetic input would be associated with multiple sites/localities. This would be expected from a sensory input that functions as a global reference frame, helping to place multiple locales (i.e., multiple local landmark arrays) into register to form a global map of familiar space.

Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Shaoheng; Guo, Jiquan; Lin, Fanglei

2015-09-01

The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energymore » ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.« less

Concurrent System Engineering and Risk Reduction for Dual-Band (RF/optical) Spacecraft Communications

NASA Technical Reports Server (NTRS)

Fielhauer, Karl, B.; Boone, Bradley, G.; Raible, Daniel, E.

2012-01-01

This paper describes a system engineering approach to examining the potential for combining elements of a deep-space RF and optical communications payload, for the purpose of reducing the size, weight and power burden on the spacecraft and the mission. Figures of merit and analytical methodologies are discussed to conduct trade studies, and several potential technology integration strategies are presented. Finally, the NASA Integrated Radio and Optical Communications (iROC) project is described, which directly addresses the combined RF and optical approach.

Radiofrequency Electric Field Heating of Conductive Media: Understanding Aqueous and Nanoparticle Heating Mechanisms and a Method for Heating Optimization

NASA Astrophysics Data System (ADS)

Lara, Nadia Chantal

Use of radiofrequency (RF) electric fields coupled with nanoparticles to enhance non-invasive hyperthermia in cancer cells and tumors sparked debate over the RF heating mechanisms of nanoparticles and the role of salts in heating. Under RF field exposure at 13.56 MHz, aqueous systems including electrolyte solutions, buffers, and blood, were shown to heat according to bulk material properties, regardless of composition. This universal aqueous heating behavior extended to suspensions of nanoparticles such as gold nanoparticles, full-length and ultra-short single-walled carbon nanotubes, and water-soluble fullerene derivatives. These suspensions displayed the same RF heating properties as saline solutions of the same conductivity, indicating that these nanoparticles themselves do not contribute to RF heating by any unique mechanism; rather, they modulate bulk conductivity, which in turn affects bulk RF heating. At 13.56 MHz, peak heating for an aqueous system occurs at a conductivity of 0.06 S/m, beyond which increases in conductivity result in reduced heating rates. Biologically relevant materials, such as blood, intra- and extracellular fluids, and most human tissues, exceed this peak heating conductivity, precluding the use of conductive materials for RF heating rate enhancement. Instead, kosmotropic or water-structuring materials, including sugars, glycols, zwitterionic molecules, and a water-soluble fullerene derivative, when added to blood or phosphate buffered saline reduced the bulk conductivity of these materials and enhanced their heating rates accordingly. A dielectric heating rate model taking into account the geometry of the sample under RF exposure was used to explain the experimental RF heating behavior of aqueous solutions and semi-aqueous materials, which generated distinct RF heating curves due to differences in bulk dielectric and physical properties.

46 CFR 111.60-2 - Specialty cable for communication and RF applications.

Code of Federal Regulations, 2012 CFR

2012-10-01

... ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-2 Specialty cable for communication and RF applications. Specialty cable such as certain coaxial cable that cannot pass the... 46 Shipping 4 2012-10-01 2012-10-01 false Specialty cable for communication and RF applications...

46 CFR 111.60-2 - Specialty cable for communication and RF applications.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-2 Specialty cable for communication and RF applications. Specialty cable such as certain coaxial cable that cannot pass the... 46 Shipping 4 2013-10-01 2013-10-01 false Specialty cable for communication and RF applications...

46 CFR 111.60-2 - Specialty cable for communication and RF applications.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-2 Specialty cable for communication and RF applications. Specialty cable such as certain coaxial cable that cannot pass the... 46 Shipping 4 2014-10-01 2014-10-01 false Specialty cable for communication and RF applications...

46 CFR 111.60-2 - Specialty cable for communication and RF applications.

Code of Federal Regulations, 2010 CFR

2010-10-01

... ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-2 Specialty cable for communication and RF applications. Specialty cable such as certain coaxial cable that cannot pass the... 46 Shipping 4 2010-10-01 2010-10-01 false Specialty cable for communication and RF applications...

46 CFR 111.60-2 - Specialty cable for communication and RF applications.

Code of Federal Regulations, 2011 CFR

2011-10-01

... ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-2 Specialty cable for communication and RF applications. Specialty cable such as certain coaxial cable that cannot pass the... 46 Shipping 4 2011-10-01 2011-10-01 false Specialty cable for communication and RF applications...

A flow cytometry-based strategy to identify and express IgM from VH1-69+ clonal peripheral B cells.

PubMed

Charles, Edgar D; Orloff, Michael I M; Dustin, Lynn B

2011-01-05

Pathologic rheumatoid factor (RF) levels are hallmarks of several human diseases. Production of monoclonal RF in vitro is essential for studies of the antigenic specificities of RF, as well as for a dissection of the mechanisms of aberrant RF+ B cell activation. We have expanded upon previous methods to develop a flow cytometry-based method to efficiently clone monoclonal antibodies (mAbs) from humans with expansions of RF-like, immunoglobulin heavy chain variable region (IgVH) 1-69 gene segment-containing B cells. The cloned variable regions are expressed as IgM and produced during culture at concentrations between 5 and 20 μg/ml. Using this system, we show that clonal Igs from patients with HCV-related mixed cryoglobulinemia, when expressed as IgM, have RF activity. We anticipate that this system will be useful for the cloning and expression of mAbs partially encoded by VH1-69 and for determination of the reactivity patterns of polyspecific, low-affinity IgMs of human pathogenic importance. Copyright © 2010 Elsevier B.V. All rights reserved.

Demonstration of Space Optical Transmitter Development for Multiple High Frequency Bands

NASA Technical Reports Server (NTRS)

Nguyen, Hung; Simons, Rainee; Wintucky, Edwin; Freeman, Jon

2013-01-01

As the demand for multiple radio frequency carrier bands continues to grow in space communication systems, the design of a cost-effective compact optical transmitter that is capable of transmitting selective multiple RF bands is of great interest, particularly for NASA Space Communications Network Programs. This paper presents experimental results that demonstrate the feasibility of a concept based on an optical wavelength division multiplexing (WDM) technique that enables multiple microwave bands with different modulation formats and bandwidths to be combined and transmitted all in one unit, resulting in many benefits to space communication systems including reduced size, weight and complexity with corresponding savings in cost. Experimental results will be presented including the individual received RF signal power spectra for the L, C, X, Ku, Ka, and Q frequency bands, and measurements of the phase noise associated with each RF frequency. Also to be presented is a swept RF frequency power spectrum showing simultaneous multiple RF frequency bands transmission. The RF frequency bands in this experiment are among those most commonly used in NASA space environment communications.

SU-E-T-558: An Exploratory RF Pulse Sequence Technique Used to Induce Differential Heating in Tissues Containing Iron Oxide Nanoparticles for a Possible Hyperthermic Adjuvant Effect to Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yee, S; Ionascu, D; Wilson, G

2014-06-01

Purpose: In pre-clinical trials of cancer thermotherapy, hyperthermia can be induced by exposing localized super-paramagnetic iron oxide nanoparticles (SPION) to external alternating magnetic fields generated by a solenoid electrical circuit (Zhao et al., Theranostics 2012). Alternatively, an RF pulse technique implemented in a regular MRI system is explored as a possible hyperthermia induction technique . Methods: A new thermal RF pulse sequence was developed using the Philips pulse programming tool for the 3T Ingenia MRI system to provide a sinusoidal magnetic field alternating at the frequency of 1.43 kHz (multiples of sine waves of 0.7 ms period) before each excitationmore » RF pulse for imaging. The duration of each thermal RF pulse routine was approximately 3 min, and the thermal pulse was applied multiple times to a phantom that contains different concentrations (high, medium and low) of SPION samples. After applying the thermal pulse each time, the temperature change was estimated by measuring the phase changes in the T1-weighted inversion-prepared multi-shot turbo field echo (TFE) sequence (TR=5.5 ms, TE=2.7 ms, inversion time=200 ms). Results: The phase values and relative differences among them changed as the number of applied thermal RF pulses increased. After the 5th application of the thermal RF pulse, the relative phase differences increased significantly, suggesting the thermal activation of the SPION. The increase of the phase difference was approximately linear with the SPION concentration. Conclusion: A sinusoidal RF pulse from the MRI system may be utilized to selectively thermally activate tissues containing super-paramagnetic iron oxide nanoparticles.« less

Sci-Fri PM: Radiation Therapy, Planning, Imaging, and Special Techniques - 09: Impact of the distance of reflective markers from linac isocenter on the positional accuracy of an infrared tracking system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ali, Elsayed; Nyiri, Balazs

Purpose: The HexaPOD™ six degree of freedom couchtop is equipped with an optical tracking system, consisting of a stereoscopic camera and a reference frame (RF) carrying infrared reflective markers. The manufacturer recommends placing the RF within 50 cm from linac isocenter (ISO), which is a serious limitation since the RF does not fit around the shoulders of most brain patients. This study quantifies the impact of extended RF distances from ISO on positional accuracy. Methods: An in-house tool with an estimated resolution of 0.3 mm and 0.1° was used. It is a large cube and a mathematical model of HexaPODmore » motion to determine the intersection of room lasers with the ruled cube edges. Combinations of translations (±1 and ±3 cm) and rotations (±2.5°) were executed on two HexaPOD couchtops for multiple RF distances from ISO (35 to 77 cm). For each combination, ten laser readings were fed into a least squares algorithm to determine the executed translations and rotations while minimizing operator reading errors. Results: The usable tracking volume is up to an RF distance of 82 cm from ISO. Positional accuracy of the HexaPOD/iGuide system is 0.6 mm and 0.1° (95% confidence). Positional accuracy variations versus RF distance from ISO are statistically insignificant (p = 0.05). Our results generally confirm recent internal estimates by the manufacturer (for future release). Conclusions: RF distances up to 77 cm from ISO are clinically acceptable, provided performing a patient safety study with a verification scan.« less

Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brombin, M., E-mail: matteo.brombin@igi.cnr.it; Spolaore, M.; Serianni, G.

2014-11-15

A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors’ holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation.more » No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.« less

Considerations for an Earth Relay Satellite with RF and Optical Trunklines

NASA Technical Reports Server (NTRS)

Israel, David J.

2016-01-01

Support for user platforms through the use of optical links to geosynchronous relay spacecraft are expected to be part of the future space communications architecture. The European Data Relay Satellite System (EDRS) has its first node, EDRS-A, in orbit. The EDRS architecture includes space-to-space optical links with a Ka-Band feeder link or trunkline. NASA's Laser Communications Relay Demonstration (LCRD) mission, originally baselined to support a space-to-space optical link relayed with an optical trunkline, has added an Radio Frequency (RF) trunkline. The use of an RF trunkline avoids the outages suffered by an optical trunkline due to clouds, but an RF trunkline will be bandwidth limited. A space relay architecture with both RF and optical trunklines could relay critical realtime data, while also providing a high data volume capacity. This paper considers the relay user scenarios that could be supported, and the implications to the space relay system and operations. System trades such as the amount of onboard processing and storage required, the use of link layer switching vs. network layer routing, and the use of Delay/Disruption Tolerant Networking (DTN) are discussed.

Thermal magnetic resonance: physics considerations and electromagnetic field simulations up to 23.5 Tesla (1GHz).

PubMed

Winter, Lukas; Oezerdem, Celal; Hoffmann, Werner; van de Lindt, Tessa; Periquito, Joao; Ji, Yiyi; Ghadjar, Pirus; Budach, Volker; Wust, Peter; Niendorf, Thoralf

2015-09-22

Glioblastoma multiforme is the most common and most aggressive malign brain tumor. The 5-year survival rate after tumor resection and adjuvant chemoradiation is only 10 %, with almost all recurrences occurring in the initially treated site. Attempts to improve local control using a higher radiation dose were not successful so that alternative additive treatments are urgently needed. Given the strong rationale for hyperthermia as part of a multimodal treatment for patients with glioblastoma, non-invasive radio frequency (RF) hyperthermia might significantly improve treatment results. A non-invasive applicator was constructed utilizing the magnetic resonance (MR) spin excitation frequency for controlled RF hyperthermia and MR imaging in an integrated system, which we refer to as thermal MR. Applicator designs at RF frequencies 300 MHz, 500 MHz and 1GHz were investigated and examined for absolute applicable thermal dose and temperature hotspot size. Electromagnetic field (EMF) and temperature simulations were performed in human voxel models. RF heating experiments were conducted at 300 MHz and 500 MHz to characterize the applicator performance and validate the simulations. The feasibility of thermal MR was demonstrated at 7.0 T. The temperature could be increased by ~11 °C in 3 min in the center of a head sized phantom. Modification of the RF phases allowed steering of a temperature hotspot to a deliberately selected location. RF heating was monitored using the integrated system for MR thermometry and high spatial resolution MRI. EMF and thermal simulations demonstrated that local RF hyperthermia using the integrated system is feasible to reach a maximum temperature in the center of the human brain of 46.8 °C after 3 min of RF heating while surface temperatures stayed below 41 °C. Using higher RF frequencies reduces the size of the temperature hotspot significantly. The opportunities and capabilities of thermal magnetic resonance for RF hyperthermia interventions of intracranial lesions are intriguing. Employing such systems as an alternative additive treatment for glioblastoma multiforme might be able to improve local control by "fighting fire with fire". Interventions are not limited to the human brain and might include temperature driven targeted drug and MR contrast agent delivery and help to understand temperature dependent bio- and physiological processes in-vivo.

State-Of High Brightness RF Photo-Injector Design

NASA Astrophysics Data System (ADS)

Ferrario, Massimo; Clendenin, Jym; Palmer, Dennis; Rosenzweig, James; Serafini, Luca

2000-04-01

The art of designing optimized high brightness electron RF Photo-Injectors has moved in the last decade from a cut and try procedure, guided by experimental experience and time consuming particle tracking simulations, up to a fast parameter space scanning, guided by recent analytical results and a fast running semi-analytical code, so to reach the optimum operating point which corresponds to maximum beam brightness. Scaling laws and the theory of invariant envelope provide to the designers excellent tools for a first parameters choice and the code HOMDYN, based on a multi-slice envelope description of the beam dynamics, is tailored to describe the space charge dominated dynamics of laminar beams in presence of time dependent space charge forces, giving rise to a very fast modeling capability for photo-injectors design. We report in this talk the results of a recent beam dynamics study, motivated by the need to redesign the LCLS photoinjector. During this work a new effective working point for a split RF photoinjector has been discovered by means of the previous mentioned approach. By a proper choice of rf gun and solenoid parameters, the emittance evolution shows a double minimum behavior in the drifting region. If the booster is located where the relative emittance maximum and the envelope waist occur, the second emittance minimum can be shifted at the booster exit and frozen at a very low level (0.3 mm-mrad for a 1 nC flat top bunch), to the extent that the invariant envelope matching conditions are satisfied.

Feed-forward and feedback projections of midbrain reticular formation neurons in the cat

PubMed Central

Perkins, Eddie; May, Paul J.; Warren, Susan

2014-01-01

Gaze changes involving the eyes and head are orchestrated by brainstem gaze centers found within the superior colliculus (SC), paramedian pontine reticular formation (PPRF), and medullary reticular formation (MdRF). The mesencephalic reticular formation (MRF) also plays a role in gaze. It receives a major input from the ipsilateral SC and contains cells that fire in relation to gaze changes. Moreover, it provides a feedback projection to the SC and feed-forward projections to the PPRF and MdRF. We sought to determine whether these MRF feedback and feed-forward projections originate from the same or different neuronal populations by utilizing paired fluorescent retrograde tracers in cats. Specifically, we tested: 1. whether MRF neurons that control eye movements form a single population by injecting the SC and PPRF with different tracers, and 2. whether MRF neurons that control head movements form a single population by injecting the SC and MdRF with different tracers. In neither case were double labeled neurons observed, indicating that feedback and feed-forward projections originate from separate MRF populations. In both cases, the labeled reticulotectal and reticuloreticular neurons were distributed bilaterally in the MRF. However, neurons projecting to the MdRF were generally constrained to the medial half of the MRF, while those projecting to the PPRF, like MRF reticulotectal neurons, were spread throughout the mediolateral axis. Thus, the medial MRF may be specialized for control of head movements, with control of eye movements being more widespread in this structure. PMID:24454280

Feed-forward and feedback projections of midbrain reticular formation neurons in the cat.

PubMed

Perkins, Eddie; May, Paul J; Warren, Susan

2014-01-10

Gaze changes involving the eyes and head are orchestrated by brainstem gaze centers found within the superior colliculus (SC), paramedian pontine reticular formation (PPRF), and medullary reticular formation (MdRF). The mesencephalic reticular formation (MRF) also plays a role in gaze. It receives a major input from the ipsilateral SC and contains cells that fire in relation to gaze changes. Moreover, it provides a feedback projection to the SC and feed-forward projections to the PPRF and MdRF. We sought to determine whether these MRF feedback and feed-forward projections originate from the same or different neuronal populations by utilizing paired fluorescent retrograde tracers in cats. Specifically, we tested: 1. whether MRF neurons that control eye movements form a single population by injecting the SC and PPRF with different tracers, and 2. whether MRF neurons that control head movements form a single population by injecting the SC and MdRF with different tracers. In neither case were double labeled neurons observed, indicating that feedback and feed-forward projections originate from separate MRF populations. In both cases, the labeled reticulotectal and reticuloreticular neurons were distributed bilaterally in the MRF. However, neurons projecting to the MdRF were generally constrained to the medial half of the MRF, while those projecting to the PPRF, like MRF reticulotectal neurons, were spread throughout the mediolateral axis. Thus, the medial MRF may be specialized for control of head movements, with control of eye movements being more widespread in this structure.

MoRFchibi SYSTEM: software tools for the identification of MoRFs in protein sequences.

PubMed

Malhis, Nawar; Jacobson, Matthew; Gsponer, Jörg

2016-07-08

Molecular recognition features, MoRFs, are short segments within longer disordered protein regions that bind to globular protein domains in a process known as disorder-to-order transition. MoRFs have been found to play a significant role in signaling and regulatory processes in cells. High-confidence computational identification of MoRFs remains an important challenge. In this work, we introduce MoRFchibi SYSTEM that contains three MoRF predictors: MoRFCHiBi, a basic predictor best suited as a component in other applications, MoRFCHiBi_ Light, ideal for high-throughput predictions and MoRFCHiBi_ Web, slower than the other two but best for high accuracy predictions. Results show that MoRFchibi SYSTEM provides more than double the precision of other predictors. MoRFchibi SYSTEM is available in three different forms: as HTML web server, RESTful web server and downloadable software at: http://www.chibi.ubc.ca/faculty/joerg-gsponer/gsponer-lab/software/morf_chibi/. © The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research.

RF low-level control for the Linac4 H{sup −} source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Butterworth, A., E-mail: andrew.butterworth@cern.ch; Grudiev, A.; Lettry, J.

2015-04-08

The H{sup −} source for the Linac4 accelerator at CERN uses an RF driven plasma for the production of H{sup −}. The RF is supplied by a 2 MHz RF tube amplifier with a maximum power output of 100 kW and a pulse duration of up to 2 ms. The low-level RF signal generation and measurement system has been developed using standard CERN controls electronics in the VME form factor. The RF frequency and amplitude reference signals are generated using separate arbitrary waveform generator channels. The frequency and amplitude are both freely programmable over the duration of the RF pulse, which allowsmore » fine-tuning of the excitation. Measurements of the forward and reverse RF power signals are performed via directional couplers using high-speed digitizers, and permit the estimation of the plasma impedance and deposited power via an equivalent circuit model. The low-level RF hardware and software implementations are described, and experimental results obtained with the Linac4 ion sources in the test stand are presented.« less

The RF Probe: providing space situational awareness through broad-spectrum detection and characterization

NASA Astrophysics Data System (ADS)

Zenick, Raymond; Kohlhepp, Kimberly; Partch, Russell

2004-09-01

AeroAstro's patented RF Probe is a system designed to address the needs of spacecraft developers and operators interested in measuring and analyzing near-field RF emissions emanating from a nearby spacecraft of interest. The RF Probe consists of an intelligent spectrum analyzer with digital signal processing capabilities combined with a calibrated, wide-bandwidth antenna and RF front end that covers the 50 kHz to 18 GHz spectrum. It is capable of acquiring signal level and signal vector information, classifying signals, assessing the quality of a satellite"s transponders, and characterizing near-field electromagnetic emissions. The RF Probe is intended for either incorporation as part of a suite of spacecraft sensors, or as a stand-alone sensor on spacecraft or other platforms such as Unmanned Aerial Vehicles (UAVs). The RF Probe was initially conceived as a tool to detect and aid in diagnosis of malfunctions in a spacecraft of interest. However, the utility of the RF Probe goes far beyond this initial concept, spanning a wide range of military applications. Most importantly, the RF Probe can provide space situational awareness for critical on-orbit assets by detecting externally induced RF fields, aiding in protection against potentially devastating attacks.

Report on the technical review workshop on the reference dose for Aroclor 1016. Held in Washington, DC on May 24-25, 1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

1994-11-01

The report includes information and material from a technical review workshop organized by the U.S. Environmental Protection Agency`s (EPA`s) Risk Assessment Forum for EPA`s Reference Dose/Reference Concentration (RfD/RfC) Work Group. The meeting was held in Washington, DC, at the Barcelo Washington Hotel on May 24-25, 1994. The subject of the technical review was the Integrated Risk Information System (IRIS) RfD entry for Aroclor 1016, a polychlorinated biphenyl (PCB). The expert technical review panel was convened to independently evaluate whether the RfD for Aroclor 1016 is based on a scientifically responsible analysis that represents full consideration of the available data andmore » clean articulation of that analysis in the IRIS RfD entry. EPA also requested panel members to consider four broad options for the Aroclor 1016 RfD as potential recommendations to the RfD/RfC Work Group.« less

Ultrananocrystalline diamond films with optimized dielectric properties for advanced RF MEMS capacitive switches

DOEpatents

Sumant, Anirudha V.; Auciello, Orlando H.; Mancini, Derrick C.

2013-01-15

An efficient deposition process is provided for fabricating reliable RF MEMS capacitive switches with multilayer ultrananocrystalline (UNCD) films for more rapid recovery, charging and discharging that is effective for more than a billion cycles of operation. Significantly, the deposition process is compatible for integration with CMOS electronics and thereby can provide monolithically integrated RF MEMS capacitive switches for use with CMOS electronic devices, such as for insertion into phase array antennas for radars and other RF communication systems.

Reverse flexing as a physical/mechanical treatment to mitigate fouling of fine bubble diffusers.

PubMed

Odize, Victory O; Novak, John; De Clippeleir, Haydee; Al-Omari, Ahmed; Smeraldi, Joshua D; Murthy, Sudhir; Rosso, Diego

2017-10-01

Achieving energy neutrality has shifted focus towards aeration system optimization, due to the high energy consumption of aeration processes in modern advanced wastewater treatment plants. A study on fine bubble diffuser fouling and mitigation, quantified by dynamic wet pressure (DWP), oxygen transfer efficiency and alpha was carried out in Blue Plains, Washington, DC. Four polyurethane fine bubble diffusers were installed in a pilot reactor column fed with high rate activated sludge from a full scale system. A mechanical cleaning method, reverse flexing (RF), was used to treat two diffusers (RF1, RF2), while two diffusers were kept as a control (i.e., no reverse flexing). There was a 45% increase in DWP of the control diffuser after 17 months of operation, an indication of fouling. RF treated diffusers (RF1 and RF2) did not show significant increase in DWP, and in comparison to the control diffuser prevented about 35% increase in DWP. Hence, reverse flexing potentially saves blower energy, by reducing the pressure burden on the air blower which increases blower energy requirement. However, no significant impact of the RF treatment in preventing a decrease in alpha-fouling (αF) of the fine pore diffusers, over time in operation was observed.

Transmit-reference methods in software defined radio platforms for communication in harsh propagation environments and systems thereof

DOEpatents

Dowla, Farid U; Nekoogar, Faranak

2015-03-03

A method for adaptive Radio Frequency (RF) jamming according to one embodiment includes dynamically monitoring a RF spectrum; detecting any undesired signals in real time from the RF spectrum; and sending a directional countermeasure signal to jam the undesired signals. A method for adaptive Radio Frequency (RF) communications according to another embodiment includes transmitting a data pulse in a RF spectrum; and transmitting a reference pulse separated by a predetermined period of time from the data pulse; wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated. A method for adaptive Radio Frequency (RF) communications according to yet another embodiment includes receiving a data pulse in a RF spectrum; and receiving a reference pulse separated in time from the data pulse, wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated; and demodulating the pulses.

Transmit-reference methods in software defined radio platforms for communication in harsh propagation environments and systems thereof

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dowla, Farid; Nekoogar, Faranak

A method for adaptive Radio Frequency (RF) jamming according to one embodiment includes dynamically monitoring a RF spectrum; detecting any undesired signals in real time from the RF spectrum; and sending a directional countermeasure signal to jam the undesired signals. A method for adaptive Radio Frequency (RF) communications according to another embodiment includes transmitting a data pulse in a RF spectrum; and transmitting a reference pulse separated by a predetermined period of time from the data pulse; wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated. A method for adaptive Radio Frequency (RF) communications accordingmore » to yet another embodiment includes receiving a data pulse in a RF spectrum; and receiving a reference pulse separated in time from the data pulse, wherein the data pulse is modulated with data, wherein the reference pulse is unmodulated; and demodulating the pulses.« less

Fiber-Optic Communication Links Suitable for On-Board Use in Modern Aircraft

NASA Technical Reports Server (NTRS)

Nguyen, Hung; Ngo, Duc; Alam, Mohammad F.; Atiquzzaman, Mohammed; Sluse, James; Slaveski, Filip

2004-01-01

The role of the Advanced Air Transportation Technologies program undertaken at the NASA Glenn Research Centers has been focused mainly on the improvement of air transportation safety, with particular emphasis on air transportation communication systems in on-board aircraft. The conventional solutions for digital optical communications systems specifically designed for local/metro area networks are, unfortunately, not capable of transporting the microwave and millimeter RF signals used in avionics systems. Optical networks capable of transporting RF signals are substantially different from the standard digital optical communications systems. The objective of this paper is to identify a number of different communication link architectures for RF/fiber optic transmission using a single backbone fiber for carrying VHF and UHF RF signals in the aircraft. To support these architectures, two approaches derived from both hybrid RF-optical and all-optical processing methodologies are discussed with single and multiple antennas for explicitly transporting VHF and UHF signals, while the relative merits and demerits of each architecture are also addressed. Furthermore, the experimental results of wavelength division multiplexing (WDM) link architecture from our test-bed platform, configured for aircraft environment to support simultaneous transmission of multiple RF signals over a single optical fiber, exhibit no appreciable signal degradation at wavelengths of both 1330 and 1550 nm, respectively. Our measurements of signal to noise ratio carried out for the transmission of FM and AM analog modulated signals at these wavelengths indicate that WDM is a fiber optic technology which is potentially suitable for avionics applications.

Biological indicators in response to radiofrequency/microwave exposure.

PubMed

Marjanović, Ana Marija; Pavičić, Ivan; Trošić, Ivančica

2012-09-01

Over the years, due to rapid technological progress, radiation from man-made sources exceeded that of natural origin. There is a general concern regarding a growing number of appliances that use radiofrequency/ microwave (RF/MW) radiation with particular emphasis on mobile communication systems. Since nonthermal biological effects and mechanisms of RF/MW radiation are still uncertain, laboratory studies on animal models, tissues, cells, and cell free system are of extraordinary importance in bioelectromagnetic research. We believe that such investigations play a supporting role in public risk assessment. Cellular systems with the potential for a clear response to RF/MW exposures should be used in those studies. It is known that organism is a complex electrochemical system where processes of oxidation and reduction regularly occur. One of the plausible mechanisms is connected with generation of reactive oxygen species (ROS). Depending on concentration, ROS can have both beneficial and deleterious effects. Positive effects are connected with cell signalling, defence against infectious agents, and proliferative cell ability. On the other hand, excessive production, which overloads antioxidant defence mechanism, leads to cellular damage with serious potential for disease development. ROS concentration increase within the cell caused by RF/MW radiation seems to be a biologically relevant hypothesis to give clear insight into the RF/MW action at non-thermal level of radiation. In order to better understand the exact mechanism of action and its consequences, further research is needed in the field. We would like to present current knowledge on possible biological mechanisms of RF/MW actions.

Can You Hear Me Now? Come in Loud and Clear with a Wireless Classroom Audio System

ERIC Educational Resources Information Center

Smith, Mark

2006-01-01

As school performance under NCLB becomes increasingly important, districts can not afford to have barriers to learning. That is where wireless sound-field amplification systems come into play. Wireless sound-field amplification systems come in two types: radio frequency (RF) and infrared (IR). RF systems are based on FCC-approved FM and UHF bands…

Characterization Of Superconducting Samples With SIC System For Thin Film Developments: Status And Recent Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, H. Lawrence; Reece, Charles E.; Valente-Feliciano, Anne-Marie

2014-02-01

Within any thin film development program directed towards SRF accelerating structures, there is a need for an RF characterization device that can provide information about RF properties of small samples. The current installation of the RF characterization device at Jefferson Lab is Surface Impedance Characterization (SIC) system. The data acquisition environment for the system has recently been improved to allow for automated measurement, and the system has been routinely used for characterization of bulk Nb, films of Nb on Cu, MgB{sub 2}, NbTiN, Nb{sub 3}Sn films, etc. We present some of the recent results that illustrate present capabilities and limitationsmore » of the system.« less

Effects of electromagnetic fields emitted by mobile phones (GSM 900 and WCDMA/UMTS) on the macrostructure of sleep.

PubMed

Danker-Hopfe, Heidi; Dorn, Hans; Bahr, Achim; Anderer, Peter; Sauter, Cornelia

2011-03-01

In the present double-blind, randomized, sham-controlled cross-over study, possible effects of electromagnetic fields emitted by Global System for Mobile Communications (GSM) 900 and Wideband Code-Division Multiple Access (WCDMA)/Universal Mobile Telecommunications System (UMTS) cell-phones on the macrostructure of sleep were investigated in a laboratory environment. An adaptation night, which served as screening night for sleep disorders and as an adjustment night to the laboratory environment, was followed by 9 study nights (separated by a 2-week interval) in which subjects were exposed to three exposure conditions (sham, GSM 900 and WCDMA/UMTS). The sample comprised 30 healthy male subjects within the age range 18-30 years (mean ± standard deviation: 25.3 ± 2.6 years). A cell-phone usage at maximum radio frequency (RF) output power was simulated and the transmitted power was adjusted in order to approach, but not to exceed, the specific absorption rate (SAR) limits of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines for general public exposure (SAR(10g) = 2.0 W kg(-1)). In this study, possible effects of long-term (8 h) continuous RF exposure on the central nervous system were analysed during sleep, because sleep is a state in which many confounding intrinsic and extrinsic factors (e.g. motivation, personality, attitude) are eliminated or controlled. Thirteen of 177 variables characterizing the initiation and maintenance of sleep in the GSM 900 and three in the WCDMA exposure condition differed from the sham condition. The few significant results are not indicative of a negative impact on sleep architecture. From the present results there is no evidence for a sleep-disturbing effect of GSM 900 and WCDMA exposure. © 2010 European Sleep Research Society.

Widely tunable opto-electronic oscillator based on a dual frequency laser

NASA Astrophysics Data System (ADS)

Maxin, J.; Saleh, K.; Pillet, G.; Morvan, L.; Llopis, O.; Dolfi, D.

2013-03-01

We present the stabilization of the beatnote of an Er,Yb:glass Dual Frequency Laser at 1.53 μm with optical fiber delay lines. Instead of standard optoelectronics oscillators, this architecture does not need RF filter and offers a wide tunability from 2.5 to 5.5 GHz. Thank to a fine analysis of the laser RIN to phase noise conversion in the photodiodes, the expected RF-amplifiers noise limit is reached with a phase noise power spectral density of -25 dBc/Hz at 10 Hz (respectively -110 dBc/Hz at 10 kHz) from the carrier over the whole tuning range. Implementation of a double fiber coil architecture improves the oscillator spectral purity: the phase noise reaches a level of -35 dBc/Hz at 10 Hz (respectively -112 dBc/Hz respectively 10 kHz) from the carrier.

Experimental study of unipolar arcs in a low pressure mercury discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, C.T.

1979-12-31

An experimental study of unipolar arcs was conducted in a low pressure mercury discharge inductively heated with RF. The results were found to be consistent with the concept of a sheath mechanism for driving the unipolar arcs. Floating double-probe measurements of the unipolar arc plasma parameters yielded electron temperatures of approx. 2 eV and electron number densities of approx. 1 x 10/sup 11/ cm/sup -3/ assuming quasi-neutral plasma conditions. The variation of the unipolar arc current with: (1) the RF power input; and (2) the metal surface area exposed to the plasma verified the predicted dependence of the arc currentmore » on the plasma parameters and the metal surface area. Finally, alternative mechanisms for sustaining the observed arcs by high frequency rectification were ruled out on the basis of the recorded current waveforms of the unipolar arcs.« less

An RF-only ion-funnel for extraction from high-pressure gases

DOE PAGES

Brunner, T.; Fudenberg, D.; Varentsov, V.; ...

2015-01-27

An RF ion-funnel technique has been developed to extract ions from a high-pressure (10 bar) noble-gas environment into a vacuum (10 -6 mbar). Detailed simulations have been performed and a prototype has been developed for the purpose of extracting 136Ba ions from Xe gas with high efficiency. With this prototype, ions have been extracted for the first time from high-pressure xenon gas and argon gas. Systematic studies have been carried out and compared to simulations. This demonstration of extraction of ions, with mass comparable to that of the gas generating the high-pressure, has applications to Ba tagging from a Xe-gasmore » time-projection chamber for double-beta decay, as well as to the general problem of recovering trace amounts of an ionized element in a heavy (m > 40 u) carrier gas.« less

Comparison of the observed and calculated coherent forward scattering spectra of the 842.5 nm Ar I and 844.6 nm O I lines in a radio frequency glow discharge

NASA Astrophysics Data System (ADS)

Matsuta, Hideyuki

2017-06-01

The coherent forward scattering (CFS) spectra of O I 844.6 nm and Ar I 842.5 nm lines in a radio frequency (RF) glow discharge were measured using a CFS spectrometer that functions in the Faraday configuration with permanent double-ring magnets and a diode-laser source. A significant change in the CFS spectrum of the Ar I 842.5 nm line was observed when the partial pressures of argon in a Hesbnd Ar RF glow discharge were changed . Based on the theoretical calculations of the CFS spectra performed using Faraday functions, a comparison between the observed and calculated spectra was performed. The CFS line profile of O I 844.6 nm and changes in the Ar I 842.5 nm CFS spectrum are explained by theoretical calculations.

Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

Extraction chromatography of the Rf homologs, Zr and Hf, using TEVA and UTEVA resins in HCl, HNO3, and H2SO4 media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alfonso, M. C.; Bennett, M. E.; Folden, C. M.

2015-06-20

The extraction behavior of the Rf homologs, Zr and Hf, has been studied in HCl, HNO3, and H2SO4 media using TEVA (R) (a trioctyl and tridecyl methyl ammonium-based resin) and UTEVA (R) (a diamyl amylphosphonate-based resin). All six systems were considered for the future chemical characterization of Rf. Batch uptake studies were first performed to determine which systems could separate Zr and Hf and these results were used to determine what acid concentration range to focus on for the column studies. The batch uptake studies showed that UTEVA separates Zr and Hf in all media, while the intergroup separation wasmore » only observed in HCl media with TEVA. Both HCl systems showed viability for potential extraction chromatographic studies of Rf.« less

Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

DOE PAGES

Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed; ...

2015-03-01

The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

Estimation of RF energy absorbed in the brain from mobile phones in the Interphone Study.

PubMed

Cardis, E; Varsier, N; Bowman, J D; Deltour, I; Figuerola, J; Mann, S; Moissonnier, M; Taki, M; Vecchia, P; Villegas, R; Vrijheid, M; Wake, K; Wiart, J

2011-09-01

The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study. We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries. The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy. While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take these into account in analyses of risk of brain tumours from RF exposure from mobile phones.

Estimation of RF energy absorbed in the brain from mobile phones in the Interphone Study

PubMed Central

Varsier, N; Bowman, J D; Deltour, I; Figuerola, J; Mann, S; Moissonnier, M; Taki, M; Vecchia, P; Villegas, R; Vrijheid, M; Wake, K; Wiart, J

2011-01-01

Objectives The objective of this study was to develop an estimate of a radio frequency (RF) dose as the amount of mobile phone RF energy absorbed at the location of a brain tumour, for use in the Interphone Epidemiological Study. Methods We systematically evaluated and quantified all the main parameters thought to influence the amount of specific RF energy absorbed in the brain from mobile telephone use. For this, we identified the likely important determinants of RF specific energy absorption rate during protocol and questionnaire design, we collected information from study subjects, network operators and laboratories involved in specific energy absorption rate measurements and we studied potential modifiers of phone output through the use of software-modified phones. Data collected were analysed to assess the relative importance of the different factors, leading to the development of an algorithm to evaluate the total cumulative specific RF energy (in joules per kilogram), or dose, absorbed at a particular location in the brain. This algorithm was applied to Interphone Study subjects in five countries. Results The main determinants of total cumulative specific RF energy from mobile phones were communication system and frequency band, location in the brain and amount and duration of mobile phone use. Though there was substantial agreement between categorisation of subjects by cumulative specific RF energy and cumulative call time, misclassification was non-negligible, particularly at higher frequency bands. Factors such as adaptive power control (except in Code Division Multiple Access networks), discontinuous transmission and conditions of phone use were found to have a relatively minor influence on total cumulative specific RF energy. Conclusions While amount and duration of use are important determinants of RF dose in the brain, their impact can be substantially modified by communication system, frequency band and location in the brain. It is important to take these into account in analyses of risk of brain tumours from RF exposure from mobile phones. PMID:21659468

Harmonic ratcheting for fast acceleration

NASA Astrophysics Data System (ADS)

Cook, N.; Brennan, J. M.; Peggs, S.

2014-04-01

A major challenge in the design of rf cavities for the acceleration of medium-energy charged ions is the need to rapidly sweep the radio frequency over a large range. From low-power medical synchrotrons to high-power accelerator driven subcritical reactor systems, and from fixed focus alternating gradient accelerators to rapid cycling synchrotrons, there is a strong need for more efficient, and faster, acceleration of protons and light ions in the semirelativistic range of hundreds of MeV/u. A conventional way to achieve a large, rapid frequency sweep (perhaps over a range of a factor of 6) is to use custom-designed ferrite-loaded cavities. Ferrite rings enable the precise tuning of the resonant frequency of a cavity, through the control of the incremental permeability that is possible by introducing a pseudoconstant azimuthal magnetic field. However, rapid changes over large permeability ranges incur anomalous behavior such as the "Q-loss" and "f-dot" loss phenomena that limit performance while requiring high bias currents. Notwithstanding the incomplete understanding of these phenomena, they can be ameliorated by introducing a "harmonic ratcheting" acceleration scheme in which two or more rf cavities take turns accelerating the beam—one turns on when the other turns off, at different harmonics—so that the radio frequency can be constrained to remain in a smaller range. Harmonic ratcheting also has straightforward performance advantages, depending on the particular parameter set at hand. In some typical cases it is possible to halve the length of the cavities, or to double the effective gap voltage, or to double the repetition rate. This paper discusses and quantifies the advantages of harmonic ratcheting in general. Simulation results for the particular case of a rapid cycling medical synchrotron ratcheting from harmonic number 9 to 2 show that stability and performance criteria are met even when realistic engineering details are taken into consideration.

Precision phase control for the radio frequency system of K500 superconducting cyclotron at Variable Energy Cyclotron Centre, Kolkata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Som, Sumit; Ghosh, Surajit; Seth, Sudeshna

2013-11-15

Variable Energy Cyclotron Centre (VECC) has commissioned K500 Superconducting cyclotron (SCC) based on MSU and Texas A and M university cyclotrons. The radio frequency (RF) system of SCC has been commissioned with the stringent requirement of various RF parameters. The three-phase RF system of Superconducting cyclotron has been developed in the frequency range 9–27 MHz with amplitude and phase stability of 100 ppm and ±0.1°, respectively. The phase control system has the option to change the relative phase difference between any two RF cavities and maintain the phase stability within ±0.1° during round-the-clock cyclotron operation. The said precision phase loopmore » consists of both analogue In-phase/Quadrature modulator to achieve faster response and also Direct Digital Synthesis based phase shifter to achieve wide dynamic range as well. This paper discusses detail insights into the various issues of phase control for the K500 SCC at VECC, Kolkata.« less

Space Station communications and tracking systems modeling and RF link simulation

NASA Technical Reports Server (NTRS)

Tsang, Chit-Sang; Chie, Chak M.; Lindsey, William C.

1986-01-01

In this final report, the effort spent on Space Station Communications and Tracking System Modeling and RF Link Simulation is described in detail. The effort is mainly divided into three parts: frequency division multiple access (FDMA) system simulation modeling and software implementation; a study on design and evaluation of a functional computerized RF link simulation/analysis system for Space Station; and a study on design and evaluation of simulation system architecture. This report documents the results of these studies. In addition, a separate User's Manual on Space Communications Simulation System (SCSS) (Version 1) documents the software developed for the Space Station FDMA communications system simulation. The final report, SCSS user's manual, and the software located in the NASA JSC system analysis division's VAX 750 computer together serve as the deliverables from LinCom for this project effort.

A Target Region Amplified Polymorphism (TRAP) Marker for Fertility Restorer Gene Rf1 and Chromosomal Localization of Rf1 and Rf2 in Cotton

USDA-ARS?s Scientific Manuscript database

Cytoplasmic male sterility (CMS), a maternally inherited trait and characterized as an inability to produce functional pollen , is an important biological system for economically producing hybrid seed to enhance crop yield and studying cytoplasmic and nuclear gene interactions. In cultivated tetrapl...

Microwave vs optical crosslink study

NASA Technical Reports Server (NTRS)

Kwong, Paulman W.; Bruno, Ronald C.; Marshalek, Robert G.

1992-01-01

The intersatellite links (ISL's) at geostationary orbit is currently a missing link in commercial satellite services. Prior studies have found that potential application of ISL's to domestic, regional, and global satellites will provide more cost-effective services than the non-ISL's systems (i.e., multiple-hop systems). In addition, ISL's can improve and expand the existing satellite services in several aspects. For example, ISL's can conserve the scarce spectrum allocated for fixed satellite services (FSS) by avoiding multiple hopping of the relay stations. ISL's can also conserve prime orbit slot by effectively expanding the geostationary arc. As a result of the coverage extension by using ISL's more users will have direct access to the satellite network, thus providing reduced signal propagation delay and improved signal quality. Given the potential benefits of ISL's system, it is of interest to determine the appropriate implementations for some potential ISL architectures. Summary of the selected ISL network architecture as supplied by NASA are listed. The projected high data rate requirements (greater than 400 Mbps) suggest that high frequency RF or optical implementations are natural approaches. Both RF and optical systems have their own merits and weaknesses which make the choice between them dependent on the specific application. Due to its relatively mature technology base, the implementation risk associated with RF (at least 32 GHz) is lower than that of the optical ISL's. However, the relatively large antenna size required by RF ISL's payload may cause real-estate problems on the host spacecraft. In addition, because of the frequency sharing (for duplex multiple channels communications) within the limited bandwidth allocated, RF ISL's are more susceptible to inter-system and inter-channel interferences. On the other hand, optical ISL's can offer interference-free transmission and compact sized payload. However, the extremely narrow beam widths (on the order of 10 micro-rad) associated with optical ISL's impose very stringent pointing, acquisition, and tracking requirements on the system. Even if the RF and optical systems are considered separately, questions still remain as to selection of RF frequency, direct versus coherent optical detection, etc. in implementing an ISL for a particular network architecture. These and other issues are studied.

Accuracy of Voltage Signal Measurement During Radiofrequency Delivery Through the SMARTTOUCH Catheter.

PubMed

Safavi-Naeini, Payam; Zafar-Awan, Dreema; Zhu, Hongjian; Zablah, Gerardo; Ganapathy, Anand V; Rasekh, Abdi; Saeed, Mohammad; Razavi, Joanna Esther Molina; Razavi, Mehdi

2017-01-01

Current methods for measuring voltage during radiofrequency (RF) ablation (RFA) necessitate turning off the ablation catheter. If voltage could be accurately read without signal attenuation during RFA, turning off the catheter would be unnecessary, allowing continuous ablation. We evaluated the accuracy of the Thermocool SMARTTOUCH catheter for measuring voltage while RF traverses the catheter. We studied 26 patients undergoing RFA for arrhythmias. A 7.5F SMARTTOUCH catheter was used for sensing voltage and performing RFA. Data were collected from the Carto-3 3-dimensional mapping system. Voltages were measured during ablation (RF-ON) and immediately before or after ablation (RF-OFF). In evaluating the accuracy of RF-ON measurements, we utilized the RF-OFF measure as the gold standard. We measured 465 voltage signals. The median values were 0.2900 and 0.3100 for RF-ON and RF-OFF, respectively. Wilcoxon signed rank testing showed no significant difference in these values (P = 0.608). The intraclass correlation coefficient (ICC) was 0.96, indicating that voltage measurements were similarly accurate during RF-OFF versus RF-ON. Five patients had baseline atrial fibrillation (AF), for whom 82 ablation points were measured; 383 additional ablation points were measured for the remaining patients. The voltages measured during RF-ON versus RF-OFF were similar in the presence of AF (P = 0.800) versus non-AF rhythm (P = 0.456) (ICC, 0.96 for both). Voltage signal measurement was similarly accurate during RF-ON versus RF-OFF independent of baseline rhythm. Physicians should consider not turning off the SMARTTOUCH ablation catheter when measuring voltage during RFA. © 2016 Wiley Periodicals, Inc.

Liquid Methane Conditioning Capabilities Developed at the NASA Glenn Research Center's Small Multi- Purpose Research Facility (SMiRF) for Accelerated Lunar Surface Storage Thermal Testing

NASA Technical Reports Server (NTRS)

Bamberger, Helmut H.; Robinson, R. Craig; Jurns, John M.; Grasl, Steven J.

2011-01-01

Glenn Research Center s Creek Road Cryogenic Complex, Small Multi-Purpose Research Facility (SMiRF) recently completed validation / checkout testing of a new liquid methane delivery system and liquid methane (LCH4) conditioning system. Facility checkout validation was conducted in preparation for a series of passive thermal control technology tests planned at SMiRF in FY10 using a flight-like propellant tank at simulated thermal environments from 140 to 350K. These tests will validate models and provide high quality data to support consideration of LCH4/LO2 propellant combination option for a lunar or planetary ascent stage.An infrastructure has been put in place which will support testing of large amounts of liquid methane at SMiRF. Extensive modifications were made to the test facility s existing liquid hydrogen system for compatibility with liquid methane. Also, a new liquid methane fluid conditioning system will enable liquid methane to be quickly densified (sub-cooled below normal boiling point) and to be quickly reheated to saturation conditions between 92 and 140 K. Fluid temperatures can be quickly adjusted to compress the overall test duration. A detailed trade study was conducted to determine an appropriate technique to liquid conditioning with regard to the SMiRF facility s existing infrastructure. In addition, a completely new roadable dewar has been procured for transportation and temporary storage of liquid methane. A new spherical, flight-representative tank has also been fabricated for integration into the vacuum chamber at SMiRF. The addition of this system to SMiRF marks the first time a large-scale liquid methane propellant test capability has been realized at Glenn.This work supports the Cryogenic Fluid Management Project being conducted under the auspices of the Exploration Technology Development Program, providing focused cryogenic fluid management technology efforts to support NASA s future robotic or human exploration missions.

Airborne characterization of smoke marker ratios from prescribed burning

NASA Astrophysics Data System (ADS)

Sullivan, A. P.; May, A. A.; Lee, T.; McMeeking, G. R.; Kreidenweis, S. M.; Akagi, S. K.; Yokelson, R. J.; Urbanski, S. P.; Collett, J. L., Jr.

2014-10-01

A Particle-Into-Liquid Sampler - Total Organic Carbon (PILS-TOC) and fraction collector system was flown aboard a Twin Otter aircraft sampling prescribed burning emissions in South Carolina in November 2011 to obtain smoke marker measurements. The fraction collector provided 2 min time-integrated offline samples for carbohydrate (i.e., smoke markers levoglucosan, mannosan, and galactosan) analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Each fire location appeared to have a unique Δlevoglucosan/Δwater-soluble organic carbon (WSOC) ratio (RF01/RF02/RF03/RF05 = 0.163 ± 0.007 μg C μg-1 C, RF08 = 0.115 ± 0.011 μg C μg-1 C, RF09A = 0.072 ± 0.028 μg C μg-1 C, and RF09B = 0.042 ± 0.008 μg C μg-1 C, where RF means research flight). These ratios were comparable to those obtained from controlled laboratory burns and suggested that the emissions sampled during RF01/F02/RF03/RF05 were dominated by the burning of grasses, RF08 by leaves, RF09A by needles, and RF09B by marsh grasses. These findings were further supported by the Δgalactosan/Δlevoglucosan ratios (RF01/RF02/RF03/RF05 = 0.067 ± 0.004 μg μg-1, RF08 = 0.085 ± 0.009 μg μg-1, and RF09A = 0.101 ± 0.029 μg μg-1) obtained as well as by the ground-based fuel and filter sample analyses during RF01/RF02/RF03/RF05. Differences between Δpotassium/Δlevoglucosan ratios obtained for these prescribed fires vs. laboratory-scale measurements suggest that some laboratory burns may not accurately represent potassium emissions from prescribed burns. The Δlevoglucosan/ΔWSOC ratio had no clear dependence on smoke age or fire dynamics suggesting that this ratio is more dependent on the type of fuel being burned. Levoglucosan was stable over a timescale of at least 1.5 h and could be useful to help estimate the air quality impacts of biomass burning.

Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de

Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating andmore » applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at positions closer to attenuating hardware structures of the RF coil. The position accuracy of the RF coil on the patient table when using the positioning frame was determined well below 1 mm for all three spatial dimensions. This ensures perfect position match between the RF coil and its three-dimensional attenuation template during the PET data reconstruction process. When applying the CT-based AC of the RF coil, the global attenuation bias was mostly compensated to ±0.5% across the entire breast imaging volume. The patient study revealed high quality MR, PET, and combined PET/MR imaging of breast cancer. Quantitative activity measurements in all 11 breast cancer lesions of the ten patients resulted in increased mean difference values of SUV{sub max} 11.8% (minimum 3.2%; maximum 23.2%) between nonAC images and images when AC of the RF breast coil was applied. This supports the quantitative results of the phantom study as well as successful attenuation correction of the RF coil. Conclusions: A 16-channel breast RF coil was designed for optimized MR imaging performance and PET transparency and was successfully integrated with its dedicated attenuation correction template into a whole-body PET/MR system. Systematic PET/MR imaging evaluation with phantoms and an initial study on patients with breast cancer provided excellent MR and PET image quality and accurate PET quantification.« less

[Study of New Micropore RF system on Lesion Formation and Complications].

PubMed

Song, Yuwen; Xu, Xiulin; Cai, Yameng

2017-07-30

To study the safety and effectiveness of a new type of micropore ablation catheter in vitro ablation system, and to provide reference for clinical practice. To evaluate two kinds of catheter in cardiac tissue ablation depth, tissue temperature and thrombosis situation by the same RF system. The power set 25 W, There was no significant difference in ablation depth between the two groups, and no Pop and thrombosis occurred. When the power is more than 40 W, two groups occurred more Pop and thrombosis. When using high power for Cardiac RF ablation, doctors should pay more attention to complications and thrombosis.

Novel Escherichia coli RF1 mutants with decreased translation termination activity and increased sensitivity to the cytotoxic effect of the bacterial toxins Kid and RelE.

PubMed

Diago-Navarro, Elizabeth; Mora, Liliana; Buckingham, Richard H; Díaz-Orejas, Ramón; Lemonnier, Marc

2009-01-01

Novel mutations in prfA, the gene for the polypeptide release factor RF1 of Escherichia coli, were isolated using a positive genetic screen based on the parD (kis, kid) toxin-antitoxin system. This original approach allowed the direct selection of mutants with altered translational termination efficiency at UAG codons. The isolated prfA mutants displayed a approximately 10-fold decrease in UAG termination efficiency with no significant changes in RF1 stability in vivo. All three mutations, G121S, G301S and R303H, were situated close to the nonsense codon recognition site in RF1:ribosome complexes. The prfA mutants displayed increased sensitivity to the RelE toxin encoded by the relBE system of E. coli, thus providing in vivo support for the functional interaction between RF1 and RelE. The prfA mutants also showed increased sensitivity to the Kid toxin. Since this toxin can cleave RNA in a ribosome-independent manner, this result was not anticipated and provided first evidence for the involvement of RF1 in the pathway of Kid toxicity. The sensitivity of the prfA mutants to RelE and Kid was restored to normal levels upon overproduction of the wild-type RF1 protein. We discuss these results and their utility for the design of novel antibacterial strategies in the light of the recently reported structure of ribosome-bound RF1.

[Development of RF coil of permanent magnet mini-magnetic resonance imager and mouse imaging experiments].

PubMed

Hou, Shulian; Xie, Huantong; Chen, Wei; Wang, Guangxin; Zhao, Qiang; Li, Shiyu

2014-10-01

In the development of radio frequency (RF) coils for better quality of the mini-type permanent magnetic resonance imager for using in the small animal imaging, the solenoid RF coil has a special advantage for permanent magnetic system based on analyses of various types.of RF coils. However, it is not satisfied for imaging if the RF coils are directly used. By theoretical analyses of the magnetic field properties produced from the solenoid coil, the research direction was determined by careful studies to raise further the uniformity of the magnetic field coil, receiving coil sensitivity for signals and signal-to-noise ratio (SNR). The method had certain advantages and avoided some shortcomings of the other different coil types, such as, birdcage coil, saddle shaped coil and phased array coil by using the alloy materials (from our own patent). The RF coils were designed, developed and made for keeled applicable to permanent magnet-type magnetic resonance imager, multi-coil combination-type, single-channel overall RF receiving coil, and applied for a patent. Mounted on three instruments (25 mm aperture, with main magnetic field strength of 0.5 T or 1.5 T, and 50 mm aperture, with main magnetic field strength of 0.48 T), we performed experiments with mice, rats, and nude mice bearing tumors. The experimental results indicated that the RF receiving coil was fully applicable to the permanent magnet-type imaging system.

Application of random forests methods to diabetic retinopathy classification analyses.

PubMed

Casanova, Ramon; Saldana, Santiago; Chew, Emily Y; Danis, Ronald P; Greven, Craig M; Ambrosius, Walter T

2014-01-01

Diabetic retinopathy (DR) is one of the leading causes of blindness in the United States and world-wide. DR is a silent disease that may go unnoticed until it is too late for effective treatment. Therefore, early detection could improve the chances of therapeutic interventions that would alleviate its effects. Graded fundus photography and systemic data from 3443 ACCORD-Eye Study participants were used to estimate Random Forest (RF) and logistic regression classifiers. We studied the impact of sample size on classifier performance and the possibility of using RF generated class conditional probabilities as metrics describing DR risk. RF measures of variable importance are used to detect factors that affect classification performance. Both types of data were informative when discriminating participants with or without DR. RF based models produced much higher classification accuracy than those based on logistic regression. Combining both types of data did not increase accuracy but did increase statistical discrimination of healthy participants who subsequently did or did not have DR events during four years of follow-up. RF variable importance criteria revealed that microaneurysms counts in both eyes seemed to play the most important role in discrimination among the graded fundus variables, while the number of medicines and diabetes duration were the most relevant among the systemic variables. We have introduced RF methods to DR classification analyses based on fundus photography data. In addition, we propose an approach to DR risk assessment based on metrics derived from graded fundus photography and systemic data. Our results suggest that RF methods could be a valuable tool to diagnose DR diagnosis and evaluate its progression.

Architecture for a 1-GHz Digital RADAR

NASA Technical Reports Server (NTRS)

Mallik, Udayan

2011-01-01

An architecture for a Direct RF-digitization Type Digital Mode RADAR was developed at GSFC in 2008. Two variations of a basic architecture were developed for use on RADAR imaging missions using aircraft and spacecraft. Both systems can operate with a pulse repetition rate up to 10 MHz with 8 received RF samples per pulse repetition interval, or at up to 19 kHz with 4K received RF samples per pulse repetition interval. The first design describes a computer architecture for a Continuous Mode RADAR transceiver with a real-time signal processing and display architecture. The architecture can operate at a high pulse repetition rate without interruption for an infinite amount of time. The second design describes a smaller and less costly burst mode RADAR that can transceive high pulse repetition rate RF signals without interruption for up to 37 seconds. The burst-mode RADAR was designed to operate on an off-line signal processing paradigm. The temporal distribution of RF samples acquired and reported to the RADAR processor remains uniform and free of distortion in both proposed architectures. The majority of the RADAR's electronics is implemented in digital CMOS (complementary metal oxide semiconductor), and analog circuits are restricted to signal amplification operations and analog to digital conversion. An implementation of the proposed systems will create a 1-GHz, Direct RF-digitization Type, L-Band Digital RADAR--the highest band achievable for Nyquist Rate, Direct RF-digitization Systems that do not implement an electronic IF downsample stage (after the receiver signal amplification stage), using commercially available off-the-shelf integrated circuits.

Submillimeter-Wave Phasor Beam-Pattern Measurement Based on Two-Stage Heterodyne Mixing With Unitary Harmonic Difference

NASA Astrophysics Data System (ADS)

Hwang, Yuh-Jing; Rao, Ramprasad; Christensen, Rob; Chen, Ming-Tang; Chu, Tah-Hsiung

2007-06-01

A near-field phasor beam measurement system is developed for the characterization of heterodyne receiver optics at submillimeter-wave frequencies. The system synthesizes a pair of submillimeter-wave signals as the RF and local oscillator (LO) sources from common reference sources. The synthesized harmonic numbers of the RF and LO sources are arranged with difference by one, which makes this a new configuration with a unitary harmonic difference. The coherent RF and LO signal are down-converted by the receiver under test, then mixed with the microwave-frequency common reference signal to generate the second-order IF signal around 100 MHz for amplitude and phase comparison. The amplitude and phase fluctuation of the measurement system at 683 GHz is within +-0.2 dB and +-4deg in a 1-h period, respectively. The system dynamic range at 683 and 250 GHz can be as high as 43 and 47 dB, respectively. The system is then used to measure the receiver beam patterns at 683 and 250 GHz with different RF transmitting probe antennas.

Novel Ultrahigh Vacuum System for Chip-Scale Trapped Ion Quantum Computing

NASA Astrophysics Data System (ADS)

Chen, Shaw-Pin; Trapped Team

2011-05-01

This presentation reports the experimental results of an ultrahigh vacuum (UHV) system as a scheme to implement scalable trapped-ion quantum computers that use micro-fabricated ion traps as fundamental building blocks. The novelty of this system resides in our design, material selection, mechanical liability, low complexity of assembly, and reduced signal interference between DC and RF electrodes. Our system utilizes RF isolation and onsite-filtering topologies to attenuate AC signals generated from the resonator. We use a UHV compatible printed circuit board (PCB) material to perform DC routing, while the RF high and RF ground received separated routing via wire-wrapping. The standard PCB fabrication process enabled us to implement ceramic-based filter components adjacent to the chip trap. The DC electrodes are connected to air-side electrical feed through using four 25D adaptors made with polyether ether ketone (PEEK). The assembly process of this system is straight forward and in-chamber structure is self-supporting. We report on initial testing of this concept with a linear chip trap fabricated by the Sandia National Labs.

Radiofrequency ablation of chondroblastoma using a multi-tined expandable electrode system: initial results.

PubMed

Tins, Bernhard; Cassar-Pullicino, Victor; McCall, Iain; Cool, Paul; Williams, David; Mangham, David

2006-04-01

The standard treatment for chondroblastoma is surgery, which can be difficult and disabling due to its apo- or epiphyseal location. Radiofrequency (RF) ablation potentially offers a minimally invasive alternative. The often large size of chondroblastomas can make treatment with plain electrode systems difficult or impossible. This article describes the preliminary experience of RF treatment of chondroblastomas with a multi-tined expandable RF electrode system. Four cases of CT guided RF treatment are described. The tumour was successfully treated in all cases. In two cases, complications occurred; infraction of a subarticular chondroblastoma in one case and cartilage and bone damage in the unaffected compartment of a knee joint in the other. Radiofrequency treatment near a joint surface threatens the integrity of cartilage and therefore long-term joint function. In weight-bearing areas, the lack of bone replacement in successfully treated lesions contributes to the risk of mechanical failure. Multi-tined expandable electrode systems allow the treatment of large chondroblastomas. In weight-bearing joints and lesions near to the articular cartilage, there is a risk of cartilage damage and mechanical weakening of the bone. In lesions without these caveats, RF ablation appears promising. The potential risks and benefits need to be evaluated for each case individually.

Narrow field electromagnetic sensor system and method

DOEpatents

McEwan, Thomas E.

1996-01-01

A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments.

Narrow field electromagnetic sensor system and method

DOEpatents

McEwan, T.E.

1996-11-19

A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments. 12 figs.

Random Forest-Based Approach for Maximum Power Point Tracking of Photovoltaic Systems Operating under Actual Environmental Conditions.

PubMed

Shareef, Hussain; Mutlag, Ammar Hussein; Mohamed, Azah

2017-01-01

Many maximum power point tracking (MPPT) algorithms have been developed in recent years to maximize the produced PV energy. These algorithms are not sufficiently robust because of fast-changing environmental conditions, efficiency, accuracy at steady-state value, and dynamics of the tracking algorithm. Thus, this paper proposes a new random forest (RF) model to improve MPPT performance. The RF model has the ability to capture the nonlinear association of patterns between predictors, such as irradiance and temperature, to determine accurate maximum power point. A RF-based tracker is designed for 25 SolarTIFSTF-120P6 PV modules, with the capacity of 3 kW peak using two high-speed sensors. For this purpose, a complete PV system is modeled using 300,000 data samples and simulated using the MATLAB/SIMULINK package. The proposed RF-based MPPT is then tested under actual environmental conditions for 24 days to validate the accuracy and dynamic response. The response of the RF-based MPPT model is also compared with that of the artificial neural network and adaptive neurofuzzy inference system algorithms for further validation. The results show that the proposed MPPT technique gives significant improvement compared with that of other techniques. In addition, the RF model passes the Bland-Altman test, with more than 95 percent acceptability.

NMR measurement system including two synchronized ring buffers, with 128 rf coils for in situ water monitoring in a polymer electrolyte fuel cell

NASA Astrophysics Data System (ADS)

Ogawa, Kuniyasu; Haishi, Tomoyuki; Aoki, Masaru; Hasegawa, Hiroshi; Morisaka, Shinichi; Hashimoto, Seitaro

2017-01-01

A small radio-frequency (rf) coil inserted into a polymer electrolyte fuel cell (PEFC) can be used to acquire nuclear magnetic resonance (NMR) signals from the water in a membrane electrode assembly (MEA) or in oxygen gas channels in the PEFC. Measuring the spatial distribution of the water in a large PEFC requires using many rf probes, so an NMR measurement system which acquires NMR signals from 128 rf probes at intervals of 0.5 s was manufactured. The system has eight rf transceiver units with a field-programmable gate array (FPGA) for modulation of the excitation pulse and quadrature phase detection of the NMR signal, and one control unit with two ring buffers for data control. The sequence data required for the NMR measurement were written into one ring buffer. The acquired NMR signal data were then written temporarily into the other ring buffer and then were transmitted to a personal computer (PC). A total of 98 rf probes were inserted into the PEFC that had an electrical generation area of 16 cm × 14 cm, and the water generated in the PEFC was measured when the PEFC operated at 100 A. As a result, time-dependent changes in the spatial distribution of the water content in the MEA and the water in the oxygen gas channels were obtained.

Random Forest-Based Approach for Maximum Power Point Tracking of Photovoltaic Systems Operating under Actual Environmental Conditions

PubMed Central

Shareef, Hussain; Mohamed, Azah

2017-01-01

Many maximum power point tracking (MPPT) algorithms have been developed in recent years to maximize the produced PV energy. These algorithms are not sufficiently robust because of fast-changing environmental conditions, efficiency, accuracy at steady-state value, and dynamics of the tracking algorithm. Thus, this paper proposes a new random forest (RF) model to improve MPPT performance. The RF model has the ability to capture the nonlinear association of patterns between predictors, such as irradiance and temperature, to determine accurate maximum power point. A RF-based tracker is designed for 25 SolarTIFSTF-120P6 PV modules, with the capacity of 3 kW peak using two high-speed sensors. For this purpose, a complete PV system is modeled using 300,000 data samples and simulated using the MATLAB/SIMULINK package. The proposed RF-based MPPT is then tested under actual environmental conditions for 24 days to validate the accuracy and dynamic response. The response of the RF-based MPPT model is also compared with that of the artificial neural network and adaptive neurofuzzy inference system algorithms for further validation. The results show that the proposed MPPT technique gives significant improvement compared with that of other techniques. In addition, the RF model passes the Bland–Altman test, with more than 95 percent acceptability. PMID:28702051

Development of a Low-Cost UAV Doppler Radar Data System

NASA Technical Reports Server (NTRS)

Knuble, Joseph; Li, Lihua; Heymsfield, Gerry

2005-01-01

A viewgraph presentation on the design of a low cost unmanned aerial vehicle (UAV) doppler radar data system is presented. The topics include: 1) Science and Mission Background; 2) Radar Requirements and Specs; 3) Radar Realization: RF System; 4) Processing of RF Signal; 5) Data System Design Process; 6) Can We Remove the DSP? 7) Determining Approximate Speed Requirements; 8) Radar Realization: Data System; 9) Data System Operation; and 10) Results.

100 km CEPC parameters and lattice design

NASA Astrophysics Data System (ADS)

Wang, D.; Gao, J.; Yu, C. H.; Zhang, Y.; Wang, Y. W.; Su, F.; Y Zhai, J.; Bai, S.; Geng, H. P.; Bian, T. J.; Wang, N.; Cui, X. H.; Zhang, C.; Qin, Q.

2017-07-01

The 100km double ring configuration with shared superconducting RF system has been defined as baseline by the circular electron positron collider (CEPC) steering committee. Based on this new scheme, we will get higher luminosity for Higgs (+170%) keeping the beam power in preliminary conceptual design report (Pre-CDR) or to reduce the beam power (19 MW) while keeping same luminosity. CEPC will be compatible with W and Z experiment. The luminosity for Z is designed at the level of 1035 cm-2s-1. The requirement for the energy acceptance of Higgs has been reduced to 1.5% by enlarging the ring to 100 km. The optics of arc and final focus system (FFS) with crab sextupoles has been designed, and also some primary dynamic aperture (DA) results were introduced. Work supported by the National Key Programme for S&T Research and Development (Grant NO. 2016YFA0400400) and the National Natural Science Foundation of China (11505198, 11575218, 11605210 and 11605211).

Simulation of InGaAs subchannel DG-HEMTs for analogue/RF applications

NASA Astrophysics Data System (ADS)

Saravana Kumar, R.; Mohanbabu, A.; Mohankumar, N.; Godwin Raj, D.

2018-03-01

The paper reports on the influence of a barrier thickness and gate length on the various device parameters of double gate high electron mobility transistors (DG-HEMTs). The DC and RF performance of the device have been studied by varying the barrier thickness from 1 to 5 nm and gate length from 10 to 150 nm, respectively. As the gate length is reduced below 50 nm regime, the barrier thickness plays an important role in device performance. Scaling the gate length leads to higher transconductance and high frequency operations with the expense of poor short channel effects. The authors claim that the 30-nm gate length, mole fractions tuned In0.53Ga0.47As/In0.7Ga0.3As/In0.53Ga0.47As subchannel DG-HEMT with optimised device structure of 2 nm In0.48Al0.52As barrier layer show a peak gm of 3.09 mS/µm, VT of 0.29 V, ION/IOFF ratio of 2.24 × 105, subthreshold slope 73 mV/decade and drain induced barrier lowering 68 mV/V with fT and fmax of 776 and 905 GHz at Vds = 0.5 V is achieved. These superior performances are achieved by using double-gate architecture with reduced gate to channel distance.

Review of ion energy and angular distributions in capacitively coupled RF plasma reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawamura, E.; Lieberman, M.A.; Birdsall, C.K.

1995-12-31

The authors present a historical review and discussion of previous works on ion energy and angular distributions (IED and IAD) arriving at the target in the collisionless regime. This regime is of great interest to experimentalists and modelers studying the new generation of high density sources in which the sheath is much thinner than in the conventional RIE systems. The purpose of the review is to asses what has been done so far, and to clarify some issues about sheaths in high density systems. Having determined the important parameters, the authors show some particle-in-cell simulation results of a dually excitedmore » capacitively coupled plasma in which the sheath ions roughly see the scaling as in high density sources. The results show that when {tau}{sub ion}/{tau}{sub rf} < 1, the oscillating voltage and width of the rf sheath significantly affect the IEDs, where {tau}{sub ion} is the ion transit-time and {tau}{sub rf} is rf period.« less

Comparison of approaches to rheumatic fever surveillance across Organisation for Economic Co-operation and Development countries.

PubMed

Oliver, Jane; Baker, Michael G; Pierse, Nevil; Carapetis, Jonathan

2015-11-01

Rheumatic fever (RF) prevention, control and surveillance are increasingly important priorities in New Zealand (NZ) and Australia. We compared RF surveillance across Organisation for Economic Co-operation and Development (OECD) member countries to assist in benchmarking and identifying useful approaches. A structured literature review was completed using Medline and PubMed databases, investigating RF incidence rates. Surveillance methods were noted. Health department websites were searched to assess whether addressing RF was a Government priority. Of 32 OECD member countries, nine reported RF incidence rates after 1999. Highest rates were seen in indigenous Australians, and NZ Māori and Pacific peoples. NZ and Australian surveillance systems are highly developed, with notification and register data compiled regularly. Only these two Governments appeared to prioritise RF surveillance and control. Other countries relied mainly on hospitalisation data. There is a lack of standardisation across incidence rate calculations. Israel and Italy may have relatively high RF rates among developed countries. RF lingers in specific populations in OECD member countries. At a minimum, RF registers are needed in higher incidence countries. Countries with low RF incidences should periodically review surveillance information to ensure rates are not increasing. © 2015 The Authors. Journal of Paediatrics and Child Health © 2015 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

CAT/RF Simulation Lessons Learned

DTIC Science & Technology

2003-06-11

IVSS-2003-MAS-7 CAT /RF Simulation Lessons Learned Christopher Mocnik Vetronics Technology Area, RDECOM TARDEC Tim Lee DCS Corporation...developed a re- configurable Unmanned Ground Vehicle (UGV) simulation for the Crew integration and Automation Test bed ( CAT ) and Robotics Follower (RF...Advanced Technology Demonstration (ATD) experiments. This simulation was developed as a component of the Embedded Simulation System (ESS) of the CAT

Assessment of the potential noncancer health hazards of PCBs for inclusion on EPA’s Integrated Risk Information System (IRIS)

EPA Science Inventory

At present, there are IRIS RfDs for two commercial PCB mixtures: Aroclor 1016 and Aroclor 1254. There is no IRIS RfD for complex PCB mixtures in general; and the RfDs for Aroclor 1016 and Aroclor 1254 were last updated in 1993 and 1994, respectively. The new assessment will integ...

Development of a prototype chest digital tomosynthesis R/F system

NASA Astrophysics Data System (ADS)

Choi, Sunghoon; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Jang, Woojin; Seo, Chang-Woo; Kim, Hee-Joung

2017-03-01

Digital tomosynthesis has an advantage of low radiation dose compared to conventional computed tomography (CT) by utilizing small number of projections ( 80) acquired over a limited angular range. It can produce 3D volumetric data although they may have some artifacts due to incomplete sampling. Based upon these attractive merits, we developed a prototype digital tomosynthesis R/F system especially for the purpose of applications in chest imaging. Prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including precise motor controller, and a reconstruction server. For image reconstruction, users could select the reconstruction option between analytic and iterative methods. Reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of the phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module was higher in images using the simultaneous algebraic reconstruction technique (SART) than those using filtered backprojection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92 sec and 86.29 sec on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from the system (5.68 mGy) could demonstrate a significant lowered radiation dose compared to conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.

Development of a prototype chest digital tomosynthesis (CDT) R/F system with fast image reconstruction using graphics processing unit (GPU) programming

NASA Astrophysics Data System (ADS)

Choi, Sunghoon; Lee, Seungwan; Lee, Haenghwa; Lee, Donghoon; Choi, Seungyeon; Shin, Jungwook; Seo, Chang-Woo; Kim, Hee-Joung

2017-03-01

Digital tomosynthesis offers the advantage of low radiation doses compared to conventional computed tomography (CT) by utilizing small numbers of projections ( 80) acquired over a limited angular range. It produces 3D volumetric data, although there are artifacts due to incomplete sampling. Based upon these characteristics, we developed a prototype digital tomosynthesis R/F system for applications in chest imaging. Our prototype chest digital tomosynthesis (CDT) R/F system contains an X-ray tube with high power R/F pulse generator, flat-panel detector, R/F table, electromechanical radiographic subsystems including a precise motor controller, and a reconstruction server. For image reconstruction, users select between analytic and iterative reconstruction methods. Our reconstructed images of Catphan700 and LUNGMAN phantoms clearly and rapidly described the internal structures of phantoms using graphics processing unit (GPU) programming. Contrast-to-noise ratio (CNR) values of the CTP682 module of Catphan700 were higher in images using a simultaneous algebraic reconstruction technique (SART) than in those using filtered back-projection (FBP) for all materials by factors of 2.60, 3.78, 5.50, 2.30, 3.70, and 2.52 for air, lung foam, low density polyethylene (LDPE), Delrin® (acetal homopolymer resin), bone 50% (hydroxyapatite), and Teflon, respectively. Total elapsed times for producing 3D volume were 2.92 s and 86.29 s on average for FBP and SART (20 iterations), respectively. The times required for reconstruction were clinically feasible. Moreover, the total radiation dose from our system (5.68 mGy) was lower than that of conventional chest CT scan. Consequently, our prototype tomosynthesis R/F system represents an important advance in digital tomosynthesis applications.

Studies and optimization of Pohang Light Source-II superconducting radio frequency system at stable top-up operation with beam current of 400 mA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joo, Youngdo, E-mail: Ydjoo77@postech.ac.kr; Yu, Inha; Park, Insoo

After three years of upgrading work, the Pohang Light Source-II (PLS-II) is now successfully operating. The final quantitative goal of PLS-II is a top-up user-service operation with beam current of 400 mA to be completed by the end of 2014. During the beam store test up to 400 mA in the storage ring (SR), it was observed that the vacuum pressure around the radio frequency (RF) window of the superconducting cavity rapidly increases over the interlock level limiting the availability of the maximum beam current storing. Although available beam current is enhanced by setting a higher RF accelerating voltage, it is bettermore » to keep the RF accelerating voltage as low as possible in the long time top-up operation. We investigated the cause of the window vacuum pressure increment by studying the changes in the electric field distribution at the superconducting cavity and waveguide according to the beam current. In our simulation, an equivalent physical modeling was developed using a finite-difference time-domain code. The simulation revealed that the electric field amplitude at the RF window is exponentially increased as the beam current increases, thus this high electric field amplitude causes a RF breakdown at the RF window, which comes with the rapid increase of window vacuum pressure. The RF accelerating voltage of PLS-II RF system was set to 4.95 MV, which was estimated using the maximum available beam current that works as a function of RF voltage, and the top-up operation test with the beam current of 400 mA was successfully carried out.« less

A NEW THERMIONIC RF ELECTRON GUN FOR SYNCHROTRON LIGHT SOURCES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kutsaev, Sergey; Agustsson, R.; Hartzell, J

A thermionic RF gun is a compact and efficient source of electrons used in many practical applications. RadiaBeam Systems and the Advanced Photon Source at Argonne National Laboratory collaborate in developing of a reliable and robust thermionic RF gun for synchrotron light sources which would offer substantial improvements over existing thermionic RF guns and allow stable operation with up to 1A of beam peak current at a 100 Hz pulse repetition rate and a 1.5 μs RF pulse length. In this paper, we discuss the electromagnetic and engineering design of the cavity and report the progress towards high power testsmore » of the cathode assembly of the new gun.« less

Recent research trends of radio-frequency biosensors for biomolecular detection.

PubMed

Lee, Hee-Jo; Yook, Jong-Gwan

2014-11-15

This article reviews radio-frequency (RF) biosensors based on passive and/or active devices and circuits. In particular, we focus on RF biosensors designed for detection of various biomolecules such as biotin-streptavidin, DNA hybridization, IgG, and glucose. The performance of these biosensors has been enhanced by the introduction of various sensing schemes with diverse nanomaterials (e.g., carbon nanotubes, graphene oxide, magnetic and gold nanoparticles, etc.). In addition, the RF biosensing platforms that can be associated with an RF active system are discussed. Finally, the challenges of RF biosensors are presented and suggestions are made for their future direction and prospects. Copyright © 2014 Elsevier B.V. All rights reserved.

Design and Optimization of AlN based RF MEMS Switches

NASA Astrophysics Data System (ADS)

Hasan Ziko, Mehadi; Koel, Ants

2018-05-01

Radio frequency microelectromechanical system (RF MEMS) switch technology might have potential to replace the semiconductor technology in future communication systems as well as communication satellites, wireless and mobile phones. This study is to explore the possibilities of RF MEMS switch design and optimization with aluminium nitride (AlN) thin film as the piezoelectric actuation material. Achieving low actuation voltage and high contact force with optimal geometry using the principle of piezoelectric effect is the main motivation for this research. Analytical and numerical modelling of single beam type RF MEMS switch used to analyse the design parameters and optimize them for the minimum actuation voltage and high contact force. An analytical model using isotropic AlN material properties used to obtain the optimal parameters. The optimized geometry of the device length, width and thickness are 2000 µm, 500 µm and 0.6 µm respectively obtained for the single beam RF MEMS switch. Low actuation voltage and high contact force with optimal geometry are less than 2 Vand 100 µN obtained by analytical analysis. Additionally, the single beam RF MEMS switch are optimized and validated by comparing the analytical and finite element modelling (FEM) analysis.

Electrostatic sensors for SPIDER experiment: Design, manufacture of prototypes, and first tests

NASA Astrophysics Data System (ADS)

Brombin, M.; Spolaore, M.; Serianni, G.; Barzon, A.; Franchin, L.; Pasqualotto, R.; Pomaro, N.; Schiesko, L.; Taliercio, C.; Trevisan, L.

2014-02-01

A system of electrostatic sensors has been designed for the SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) experiment, prototype RF source of the ITER NBI (neutral beam injection). A prototype of the sensor system was manufactured and tested at the BATMAN (BAvarian Test MAchine for Negative ions) facility, where the plasma environment is similar to that of SPIDER. Different aspects concerning the mechanical manufacturing and the signal conditioning are presented, among them the RF compensation adopted to reduce the RF effects which could lead to overestimated values of the electron temperature. The first commissioning tests provided ion saturation current values in the range assumed for the design, so the deduced plasma density estimate is consistent with the expected values.

Electrostatic sensors for SPIDER experiment: design, manufacture of prototypes, and first tests.

PubMed

Brombin, M; Spolaore, M; Serianni, G; Barzon, A; Franchin, L; Pasqualotto, R; Pomaro, N; Schiesko, L; Taliercio, C; Trevisan, L

2014-02-01

A system of electrostatic sensors has been designed for the SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) experiment, prototype RF source of the ITER NBI (neutral beam injection). A prototype of the sensor system was manufactured and tested at the BATMAN (BAvarian Test MAchine for Negative ions) facility, where the plasma environment is similar to that of SPIDER. Different aspects concerning the mechanical manufacturing and the signal conditioning are presented, among them the RF compensation adopted to reduce the RF effects which could lead to overestimated values of the electron temperature. The first commissioning tests provided ion saturation current values in the range assumed for the design, so the deduced plasma density estimate is consistent with the expected values.

Electrostatic sensors for SPIDER experiment: Design, manufacture of prototypes, and first tests

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brombin, M., E-mail: matteo.brombin@igi.cnr.it; Spolaore, M.; Serianni, G.

2014-02-15

A system of electrostatic sensors has been designed for the SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) experiment, prototype RF source of the ITER NBI (neutral beam injection). A prototype of the sensor system was manufactured and tested at the BATMAN (BAvarian Test MAchine for Negative ions) facility, where the plasma environment is similar to that of SPIDER. Different aspects concerning the mechanical manufacturing and the signal conditioning are presented, among them the RF compensation adopted to reduce the RF effects which could lead to overestimated values of the electron temperature. The first commissioningmore » tests provided ion saturation current values in the range assumed for the design, so the deduced plasma density estimate is consistent with the expected values.« less

Real-time cavity simulator-based low-level radio-frequency test bench and applications for accelerators

NASA Astrophysics Data System (ADS)

Qiu, Feng; Michizono, Shinichiro; Miura, Takako; Matsumoto, Toshihiro; Liu, Na; Wibowo, Sigit Basuki

2018-03-01

A Low-level radio-frequency (LLRF) control systems is required to regulate the rf field in the rf cavity used for beam acceleration. As the LLRF system is usually complex, testing of the basic functions or control algorithms of this system in real time and in advance of beam commissioning is strongly recommended. However, the equipment necessary to test the LLRF system, such as superconducting cavities and high-power rf sources, is very expensive; therefore, we have developed a field-programmable gate array (FPGA)-based cavity simulator as a substitute for real rf cavities. Digital models of the cavity and other rf systems are implemented in the FPGA. The main components include cavity baseband models for the fundamental and parasitic modes, a mechanical model of the Lorentz force detuning, and a model of the beam current. Furthermore, in our simulator, the disturbance model used to simulate the power-supply ripples and microphonics is also carefully considered. Based on the presented cavity simulator, we have established an LLRF system test bench that can be applied to different cavity operational conditions. The simulator performance has been verified by comparison with real cavities in KEK accelerators. In this paper, the development and implementation of this cavity simulator is presented first, and the LLRF test bench based on the presented simulator is constructed. The results are then compared with those for KEK accelerators. Finally, several LLRF applications of the cavity simulator are illustrated.

Using the ATL HDI 1000 to collect demodulated RF data for monitoring HIFU lesion formation

NASA Astrophysics Data System (ADS)

Anand, Ajay; Kaczkowski, Peter J.; Daigle, Ron E.; Huang, Lingyun; Paun, Marla; Beach, Kirk W.; Crum, Lawrence A.

2003-05-01

The ability to accurately track and monitor the progress of lesion formation during HIFU (High Intensity Focused Ultrasound) therapy is important for the success of HIFU-based treatment protocols. To aid in the development of algorithms for accurately targeting and monitoring formation of HIFU induced lesions, we have developed a software system to perform RF data acquisition during HIFU therapy using a commercially available clinical ultrasound scanner (ATL HDI 1000, Philips Medical Systems, Bothell, WA). The HDI 1000 scanner functions on a software dominant architecture, permitting straightforward external control of its operation and relatively easy access to quadrature demodulated RF data. A PC running a custom developed program sends control signals to the HIFU module via GPIB and to the HDI 1000 via Telnet, alternately interleaving HIFU exposures and RF frame acquisitions. The system was tested during experiments in which HIFU lesions were created in excised animal tissue. No crosstalk between the HIFU beam and the ultrasound imager was detected, thus demonstrating synchronization. Newly developed acquisition modes allow greater user control in setting the image geometry and scanline density, and enables high frame rate acquisition. This system facilitates rapid development of signal-processing based HIFU therapy monitoring algorithms and their implementation in image-guided thermal therapy systems. In addition, the HDI 1000 system can be easily customized for use with other emerging imaging modalities that require access to the RF data such as elastographic methods and new Doppler-based imaging and tissue characterization techniques.

Matching network for RF plasma source

DOEpatents

Pickard, Daniel S.; Leung, Ka-Ngo

2007-11-20

A compact matching network couples an RF power supply to an RF antenna in a plasma generator. The simple and compact impedance matching network matches the plasma load to the impedance of a coaxial transmission line and the output impedance of an RF amplifier at radio frequencies. The matching network is formed of a resonantly tuned circuit formed of a variable capacitor and an inductor in a series resonance configuration, and a ferrite core transformer coupled to the resonantly tuned circuit. This matching network is compact enough to fit in existing compact focused ion beam systems.

Focused electron and ion beam systems

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

2004-07-27

An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

8.0-Tesla human MR system: temperature changes associated with radiofrequency-induced heating of a head phantom.

PubMed

Kangarlu, Allahyar; Shellock, Frank G; Chakeres, Donald W

2003-02-01

To investigate if the heat induced in biological tissues by typical radio frequency (RF) energy associated with an 8.0-Tesla magnetic resonance (MR) system causes excessive temperature changes. Fluoroptic thermometry was used to measure temperatures in multiple positions in a head phantom made of ground turkey breast. A series of experiments were conducted with measurements obtained at RF power levels ranging from a specific absorption rate (SAR) of up to 4.0 W/kg for 10 minutes. The highest temperature increases were up to 0.7 degrees C. An inhomogeneous heating pattern was observed. In general, the deep regions within the phantom registered higher temperature increases compared to the peripheral sites. The expectation of an inhomogeneous RF distribution in ultra high field systems (> 4 T) was confirmed. At a frequency of 340 MHz and in-tissue RF wave length of about 10 cm, the RF inhomogeneity was measured to create higher temperatures in deeper regions of a human head phantom compared to peripheral tissues. Our results agree with the computational electromagnetic calculations for such frequencies. Importantly, these experiments indicated that there were no regions of heating that exceeded the current FDA guidelines. Copyright 2003 Wiley-Liss, Inc.

Experimental Study of RF Sheath Formation on a Fast Wave Antenna and Limiter in the LAPD

NASA Astrophysics Data System (ADS)

Martin, Michael; Gekelman, Walter; Pribyl, Patrick; van Compernolle, Bart; Carter, Troy

2015-11-01

Ion cyclotron resonance heating (ICRH) will be an essential component of heating power in ITER. During ICRH, radio frequency (RF) sheaths may form both at the exciting antenna and further away, e.g. in the divertor region, and may cause wall material sputtering and decreased RF power coupling to the plasma. It is important to do detailed laboratory experiments that fully diagnose the sheaths and wave fields. This is not possible in fusion devices. A new RF system has recently been constructed for performing such studies in the LAPD plasma column (ne ~1012 -1013cm-3 , Te ~ 1 - 10 eV ,B0 ~ 400 - 2000 G , diameter ~ 60cm , length ~ 18 m) . The RF system is capable of pulsing at the 1 Hz rep. rate of the LAPD plasma and operating between 2-6 MHz (1st - 9th harmonic of fci in H) with a power output of 200 kW. First results of this system driving a single-strap fast wave antenna will be presented. Emissive and Langmuir probe measurements in the vicinity of both the antenna and a remote limiter and wave coupling measured by magnetic pickup loops will be presented.

Center conductor diagnostic for multipactor detection in inaccessible geometries.

PubMed

Chaplin, Vernon H; Hubble, Aimee A; Clements, Kathryn A; Graves, Timothy P

2017-01-01

Electron collecting current probes are the most reliable diagnostic of multipactor and radiofrequency (RF) ionization breakdown; however, stand-alone probes can only be used in test setups where the breakdown region is physically accessible. This paper describes techniques for measuring multipactor current directly on the center conductor of a coaxial RF device (or more generally, on the signal line in any two-conductor RF system) enabling global multipactor detection with improved sensitivity compared to other common diagnostics such as phase null, third harmonic, and reflected power. The center conductor diagnostic may be AC coupled for use in systems with a low DC impedance between the center conductor and ground. The effect of DC bias on the breakdown threshold was studied: in coaxial geometry, the change in threshold was <1 dB for positive biases satisfying V DC /V RF0 <0.8, where V RF0 is the RF voltage amplitude at the unperturbed breakdown threshold. In parallel plate geometry, setting V DC /V RF0 <0.2 was necessary to avoid altering the threshold by more than 1 dB. In most cases, the center conductor diagnostic functions effectively with no bias at all-this is the preferred implementation, but biases in the range V DC =0-10V may be applied if necessary. The polarity of the detected current signal may be positive or negative depending on whether there is net electron collection or emission globally.

Electronic characterization of lithographically patterned microcoils for high sensitivity NMR detection.

PubMed

Demas, Vasiliki; Bernhardt, Anthony; Malba, Vince; Adams, Kristl L; Evans, Lee; Harvey, Christopher; Maxwell, Robert S; Herberg, Julie L

2009-09-01

Nuclear magnetic resonance (NMR) offers a non-destructive, powerful, structure-specific analytical method for the identification of chemical and biological systems. The use of radio frequency (RF) microcoils has been shown to increase the sensitivity in mass-limited samples. Recent advances in micro-receiver technology have further demonstrated a substantial increase in mass sensitivity [D.L. Olson, T.L. Peck, A.G. Webb, R.L. Magin, J.V. Sweedler, High-resolution microcoil H-1-NMR for mass-limited, nanoliter-volume samples, Science 270 (5244) (1995) 1967-1970]. Lithographic methods for producing solenoid microcoils possess a level of flexibility and reproducibility that exceeds previous production methods, such as hand winding microcoils. This paper presents electrical characterizations of RF microcoils produced by a unique laser lithography system that can pattern three dimensional surfaces and compares calculated and experimental results to those for wire wound RF microcoils. We show that existing optimization conditions for RF coil design still hold true for RF microcoils produced by lithography. Current lithographic microcoils show somewhat inferior performance to wire wound RF microcoils due to limitations in the existing electroplating technique. In principle, however, when the pitch of the RF microcoil is less than 100mum lithographic coils should show comparable performance to wire wound coils. In the cases of larger pitch, wire cross sections can be significantly larger and resistances lower than microfabricated conductors.

The protective effect of autophagy on mouse spermatocyte derived cells exposure to 1800MHz radiofrequency electromagnetic radiation.

PubMed

Liu, Kaijun; Zhang, Guowei; Wang, Zhi; Liu, Yong; Dong, Jianyun; Dong, Xiaomei; Liu, Jinyi; Cao, Jia; Ao, Lin; Zhang, Shaoxiang

2014-08-04

The increasing exposure to radiofrequency (RF) radiation emitted from mobile phone use has raised public concern regarding the biological effects of RF exposure on the male reproductive system. Autophagy contributes to maintaining intracellular homeostasis under environmental stress. To clarify whether RF exposure could induce autophagy in the spermatocyte, mouse spermatocyte-derived cells (GC-2) were exposed to 1800MHz Global System for Mobile Communication (GSM) signals in GSM-Talk mode at specific absorption rate (SAR) values of 1w/kg, 2w/kg or 4w/kg for 24h, respectively. The results indicated that the expression of LC3-II increased in a dose- and time-dependent manner with RF exposure, and showed a significant change at the SAR value of 4w/kg. The autophagosome formation and the occurrence of autophagy were further confirmed by GFP-LC3 transient transfection assay and transmission electron microscopy (TEM) analysis. Furthermore, the conversion of LC3-I to LC3-II was enhanced by co-treatment with Chloroquine (CQ), indicating autophagic flux could be enhanced by RF exposure. Intracellular ROS levels significantly increased in a dose- and time-dependent manner after cells were exposed to RF. Pretreatment with anti-oxidative NAC obviously decreased the conversion of LC3-I to LC3-II and attenuated the degradation of p62 induced by RF exposure. Meanwhile, phosphorylated extracellular-signal-regulated kinase (ERK) significantly increased after RF exposure at the SAR value of 2w/kg and 4w/kg. Moreover, we observed that RF exposure did not increase the percentage of apoptotic cells, but inhibition of autophagy could increase the percentage of apoptotic cells. These findings suggested that autophagy flux could be enhanced by 1800MHz GSM exposure (4w/kg), which is mediated by ROS generation. Autophagy may play an important role in preventing cells from apoptotic cell death under RF exposure stress. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Wireless Orbiter Hang-Angle Inclinometer System

NASA Technical Reports Server (NTRS)

Lucena, Angel; Perotti, Jose; Green, Eric; Byon, Jonathan; Burns, Bradley; Mata, Carlos; Randazzo, John; Blalock, Norman

2011-01-01

A document describes a system to reliably gather the hang-angle inclination of the orbiter. The system comprises a wireless handheld master station (which contains the main station software) and a wireless remote station (which contains the inclinometer sensors, the RF transceivers, and the remote station software). The remote station is designed to provide redundancy to the system. It includes two RF transceivers, two power-management boards, and four inclinometer sensors.

Novel Escherichia coli RF1 mutants with decreased translation termination activity and increased sensitivity to the cytotoxic effect of the bacterial toxins Kid and RelE

PubMed Central

Diago-Navarro, Elizabeth; Mora, Liliana; Buckingham, Richard H; Díaz-Orejas, Ramón; Lemonnier, Marc

2008-01-01

Novel mutations in prfA, the gene for the polypeptide release factor RF1 of Escherichia coli, were isolated using a positive genetic screen based on the parD (kis, kid) toxin–antitoxin system. This original approach allowed the direct selection of mutants with altered translational termination efficiency at UAG codons. The isolated prfA mutants displayed a ∼10-fold decrease in UAG termination efficiency with no significant changes in RF1 stability in vivo. All three mutations, G121S, G301S and R303H, were situated close to the nonsense codon recognition site in RF1:ribosome complexes. The prfA mutants displayed increased sensitivity to the RelE toxin encoded by the relBE system of E. coli, thus providing in vivo support for the functional interaction between RF1 and RelE. The prfA mutants also showed increased sensitivity to the Kid toxin. Since this toxin can cleave RNA in a ribosome-independent manner, this result was not anticipated and provided first evidence for the involvement of RF1 in the pathway of Kid toxicity. The sensitivity of the prfA mutants to RelE and Kid was restored to normal levels upon overproduction of the wild-type RF1 protein. We discuss these results and their utility for the design of novel antibacterial strategies in the light of the recently reported structure of ribosome-bound RF1. PMID:19019162

Identifying possible non-thermal effects of radio frequency energy on inactivating food microorganisms.

PubMed

Kou, Xiaoxi; Li, Rui; Hou, Lixia; Zhang, Lihui; Wang, Shaojin

2018-03-23

Radio frequency (RF) heating has been successfully used for inactivating microorganisms in agricultural and food products. Athermal (non-thermal) effects of RF energy on microorganisms have been frequently proposed in the literature, resulting in difficulties for developing effective thermal treatment protocols. The purpose of this study was to identify if the athermal inactivation of microorganisms existed during RF treatments. Escherichia coli and Staphylococcus aureus in apple juice and mashed potato were exposed to both RF and conventional thermal energies to compare their inactivation populations. A thermal death time (TDT) heating block system was used as conventional thermal energy source to simulate the same heating treatment conditions, involving heating temperature, heating rate and uniformity, of a RF treatment at a frequency of 27.12 MHz. Results showed that a similar and uniform temperature distribution in tested samples was achieved in both heating systems, so that the central sample temperature could be used as representative one for evaluating thermal inactivation of microorganisms. The survival patterns of two target microorganisms in two food samples were similar both for RF and heating block treatments since their absolute difference of survival populations was <1 log CFU/ml. The statistical analysis indicated no significant difference (P > 0.05) in inactivating bacteria between the RF and the heating block treatments at each set of temperatures. The solid temperature and microbial inactivation data demonstrated that only thermal effect of RF energy at 27.12 MHz was observed on inactivating microorganisms in foods. Copyright © 2018 Elsevier B.V. All rights reserved.

Wireless-powered electroactive soft microgripper

NASA Astrophysics Data System (ADS)

Cheong, Hau Ran; Teo, Choon Yee; Leow, Pei Ling; Lai, Koon Chun; Chee, Pei Song

2018-05-01

This paper presents a wireless powered single active finger ionic polymer metal composite (IPMC) based microgripper that is operated using external radio-frequency (RF) magnetic field for biological cell manipulation application. A unimorph-like active finger is fabricated by integrating the IPMC actuator to the planar resonant LC receiver and DC rectifier circuits (made of flexible double-sided copper clad polyimide). The finger activated when the device is exposed to the external magnetic field generated by transmitter circuit that matches the resonant frequency of LC receiver circuit, ∼13.6 MHz in magnetic resonant coupling power transfer mechanism. The fabricated prototype shows a maximum IPMC deflection of 0.765 mm (activation force of 0.17 mN) at the RF power of 0.65 W with 3.5 VDC supplied from the LC receiver circuit. Three repeated ON-OFF wireless activation cycle was performed with the reported cumulative deflection of 0.57 mm. The cumulative deflection was increased to 1.17 mm, 1.19 mm and 1.24 mm for three different samples respectively at 5 VDC supplied. As a proof of concept, fish egg was used to represent the biological cell manipulation operation. The microgripper successfully gripped the fish egg sample without any damages. The experiments result validates the effectiveness of wireless RF soft microgripper towards the target application.

Performance characterization of a permanent-magnet helicon plasma thruster

NASA Astrophysics Data System (ADS)

Takahashi, Kazunori; Charles, Christine; Boswell, Rod

2012-10-01

Helicon plasma thrusters operated at a few kWs of rf power is an active area of an international research. Recent experiments have clarified part of the thrust-generation mechanisms. Thrust components which have been identified include an electron pressure inside the source region and a Lorentz force due to an electron diamagnetic drift current and a radial component of the applied magnetic field. The use of permanent magnets (PMs) instead of solenoids is one of the solutions for improving the thruster efficiency because it does not require electricity for the magnetic nozzle formation. Here the thrust imparted from a permanent-magnet helicon plasma thruster is directly measured using a pendulum thrust balance. The source consists of permanent magnet (PM) arrays, a double turn rf loop antenna powered by a 13.56 MHz rf generator and a glass source tube. The PM arrays provide a magnetic nozzle near the open exit of the source and two configurations, which have maximum field strengths of about 100 and 270 G, are tested. A thrust of 15 mN, specific impulse of 2000 sec and a thrust efficiency of 8 percent are presently obtained for 2 kW of input power, 24 sccm flow rate of argon and the stronger magnetic field configuration.

Application of Random Forests Methods to Diabetic Retinopathy Classification Analyses

PubMed Central

Casanova, Ramon; Saldana, Santiago; Chew, Emily Y.; Danis, Ronald P.; Greven, Craig M.; Ambrosius, Walter T.

2014-01-01

Background Diabetic retinopathy (DR) is one of the leading causes of blindness in the United States and world-wide. DR is a silent disease that may go unnoticed until it is too late for effective treatment. Therefore, early detection could improve the chances of therapeutic interventions that would alleviate its effects. Methodology Graded fundus photography and systemic data from 3443 ACCORD-Eye Study participants were used to estimate Random Forest (RF) and logistic regression classifiers. We studied the impact of sample size on classifier performance and the possibility of using RF generated class conditional probabilities as metrics describing DR risk. RF measures of variable importance are used to detect factors that affect classification performance. Principal Findings Both types of data were informative when discriminating participants with or without DR. RF based models produced much higher classification accuracy than those based on logistic regression. Combining both types of data did not increase accuracy but did increase statistical discrimination of healthy participants who subsequently did or did not have DR events during four years of follow-up. RF variable importance criteria revealed that microaneurysms counts in both eyes seemed to play the most important role in discrimination among the graded fundus variables, while the number of medicines and diabetes duration were the most relevant among the systemic variables. Conclusions and Significance We have introduced RF methods to DR classification analyses based on fundus photography data. In addition, we propose an approach to DR risk assessment based on metrics derived from graded fundus photography and systemic data. Our results suggest that RF methods could be a valuable tool to diagnose DR diagnosis and evaluate its progression. PMID:24940623

Radiofrequency heating of metallic dental devices during 3.0 T MRI

PubMed Central

Hasegawa, M; Miyata, K; Abe, Y; Ishigami, T

2013-01-01

Objectives: To estimate the risk of injury from radiofrequency (RF) heating of metallic dental devices in use during 3.0 T MRI. Methods: The whole-body specific absorption rate (WB-SAR) was calculated on the basis of saline temperature elevation under the maximum RF irradiation for 15 min to determine the operation parameters for the heating test. The temperature changes of three types of three-unit bridges, a full-arch fixed dental prosthesis and an orthodontic appliance in use during MRI with a 3.0 T MR system (Magnetom® Verio; Siemens AG, Erlangen, Germany) were then tested in accordance with the American Society for Testing and Materials F2182-09 standardized procedure under the maximum RF heating during 15 min RF irradiation. Results: The system console-predicted WB-SAR was approximately 1.4 W kg−1 and that measured with a saline phantom was 2.1 W kg−1. In the assessment of RF heating, the highest temperature increase was +1.80 °C in the bridges, +1.59 °C in the full-arch fixed dental prosthesis and +2.61 °C in the orthodontic appliance. Conclusions: The relatively minor RF heating of dental casting material-based prostheses in Magnetom Verio systems in the normal operating mode should not pose a risk to patients. However, orthodontic appliances may exhibit RF heating above the industrial standard (CENELEC standard prEN45502-2-3); therefore, the wire should be removed from the bracket or a spacer should be used between the appliance and the oral mucosa during MRI. PMID:23520391

Experimental investigation of current free double layers in helicon plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahu, B. B.; Tarey, R. D.; Ganguli, A.

2014-02-15

The paper presents investigations of current free double layer (CFDL) that forms in helicon plasmas. In contrast to the other work reporting on the same subject, in the present investigations the double layer (DL) forms in a mirror-like magnetic field topology. The RF compensated Langmuir probe measurements show multiple DLs, which are in connection with, the abrupt fall of densities along with potential drop of about 24 V and 18 V. The DLs strengths (e ΔV{sub p})/(k T{sub e}) are about 9.5 and 6, and the corresponding widths are about 6 and 5 D lengths. The potential drop is nearly equal tomore » the thermal anisotropies between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike the earlier studies on the DL formation in the region of strong gradients in the magnetic field. Also, it presents a qualitative discussion on the mechanism of DL formation.« less

Prevalence of positive autoimmune biomarkers in the brucellosis patients.

PubMed

Ahmadinejad, Zahra; Abdollahi, Alireza; Ziaee, Vahid; Domiraei, Zeinab; Najafizadeh, Seyed-Reza; Jafari, Sirus; Ahmadinejad, Mahdi

2016-10-01

Brucellosis is a chronic infectious disease with articular involvement. Discrimination between brucellosis and rheumatologic disorders is difficult in regions endemic for brucellosis. There are few studies about the rate of positive autoantibodies as rheumatologic biomarkers in brucellosis, and the prevalence is variable. In this study, the rheumatologic tests were studied in brucellosis patients. This cross sectional study was performed in two teaching hospitals in Tehran, Iran. Forty-nine patients with brucella infection and 42 healthy participants were enrolled in this study. Brucellosis was diagnosed on the basis of the clinical symptoms and positive serology for brucellosis. Rheumatic factor (RF) and antinuclear antibodies (ANA) were evaluated in all patients. Cyclic citrullinated peptides antibody (ACPA) and anti-double strand DNA (anti-dsDNA) were checked in all patients and control groups. Out of 49 patients, 15 (30.6 %) were RF positive and 4 (8.2 %) were ANA positive. Anti-dsDNA was concurrently positive with ANA in 1 patient (2 %) but ACPA titer was positive in 8 patients (16.3 %). None of the patients with positive autoantibody biomarkers fulfilled the criteria for rheumatologic disorders. The rate of positive RF in healthy people was significantly lower than patient group (2.4 vs. 30.6 %), but the positiveness rate of other biomarkers did not have significant difference in two groups. Sixty percent of the patients with positive RF and 75 % with positive ACPA had skeletal involvement (P < 0.05). Autoantibody biomarkers can be positive in brucellosis. Rheumatologists should be aware of brucellosis in patients with musculoskeletal involvement and positive autoantibody biomarkers in endemic regions.

MR-compatibility assessment of MADPET4: a study of interferences between an SiPM-based PET insert and a 7 T MRI system.

PubMed

Omidvari, Negar; Topping, Geoffrey; Cabello, Jorge; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I

2018-05-01

Compromises in the design of a positron emission tomography (PET) insert for a magnetic resonance imaging (MRI) system should minimize the deterioration of image quality in both modalities, particularly when simultaneous demanding acquisitions are performed. In this work, the advantages of using individually read-out crystals with high-gain silicon photomultipliers (SiPMs) were studied with a small animal PET insert for a 7 T MRI system, in which the SiPM charge was transferred to outside the MRI scanner using coaxial cables. The interferences between the two systems were studied with three radio-frequency (RF) coil configurations. The effects of PET on the static magnetic field, flip angle distribution, RF noise, and image quality of various MRI sequences (gradient echo, spin echo, and echo planar imaging (EPI) at 1 H frequency, and chemical shift imaging at 13 C frequency) were investigated. The effects of fast-switching gradient fields and RF pulses on PET count rate were studied, while the PET insert and the readout electronics were not shielded. Operating the insert inside a 1 H volume coil, used for RF transmission and reception, limited the MRI to T1-weighted imaging, due to coil detuning and RF attenuation, and resulted in significant PET count loss. Using a surface receive coil allowed all tested MR sequences to be used with the insert, with 45-59% signal-to-noise ratio (SNR) degradation, compared to without PET. With a 1 H/ 13 C volume coil inside the insert and shielded by a copper tube, the SNR degradation was limited to 23-30% with all tested sequences. The insert did not introduce any discernible distortions into images of two tested EPI sequences. Use of truncated sinc shaped RF excitation pulses and gradient field switching had negligible effects on PET count rate. However, PET count rate was substantially affected by high-power RF block pulses and temperature variations due to high gradient duty cycles.

RF MEMS devices for multifunctional integrated circuits and antennas

NASA Astrophysics Data System (ADS)

Peroulis, Dimitrios

Micromachining and RF Micro-Electro-Mechanical Systems (RF MEMS) have been identified as two of the most significant enabling technologies in developing miniaturized low-cost communications systems and sensor networks. The key components in these MEMS-based architectures are the RF MEMS switches and varactors. The first part of this thesis focuses on three novel RF MEMS components with state-of-the-art performance. In particular, a broadband 6 V capacitive MEMS switch is presented with insertion loss of only 0.04 and 0.17 dB at 10 and 40 GHz respectively. Special consideration is given to particularly challenging issues, such as residual stress, planarity, power handling capability and switching speed. The need for switches operating below 1 GHz is also identified and a spring-loaded metal-to-metal contact switch is developed. The measured on-state contact resistance and off-state series capacitance are 0.5 O and 10 fF respectively for this switch. An analog millimeter-wave variable capacitor is the third MEMS component presented in this thesis. This variable capacitor shows an ultra high measured tuning range of nearly 4:1, which is the highest reported value for the millimeter-wave region. The second part of this thesis primarily concentrates on MEMS-based reconfigurable systems and their potential to revolutionize the design of future RF/microwave multifunctional systems. High-isolation switches and switch packets with isolation of more than 60 dB are designed and implemented. Furthermore, lowpass and bandpass tunable filters with 3:1 and 2:1 tuning ratios respectively are demonstrated. Similar methods have been also applied to the field of slot antennas and a novel design technique for compact reconfigurable antennas has been developed. The main advantage of these antennas is that they essentially preserve their impedance, radiation pattern, polarization, gain and efficiency for all operating frequencies. The thesis concludes by discussing the future challenges of RF MEMS, such as packaging and reliability.

Antiproton acceleration in the Fermilab Main Ring and Tevatron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martin, P.; Dinkel, J.; Ducar, R.

1987-03-01

The operation of the Fermilab Main Ring and Tevatron rf systems for colliding beams physics is discussed. The changes in the rf feedback system required for the accelration of antiprotons, and the methods for achieving proper transfer of both protons and antiprotons are described. Data on acceleration and transfer efficiencies are presented.

A strip-shield improves the efficiency of a solenoid coil in probes for high-field solid-state NMR of lossy biological samples.

PubMed

Wu, Chin H; Grant, Christopher V; Cook, Gabriel A; Park, Sang Ho; Opella, Stanley J

2009-09-01

A strip-shield inserted between a high inductance double-tuned solenoid coil and the glass tube containing the sample improves the efficiency of probes used for high-field solid-state NMR experiments on lossy aqueous samples of proteins and other biopolymers. A strip-shield is a coil liner consisting of thin copper strips layered on a PTFE (polytetrafluoroethylene) insulator. With lossy samples, the shift in tuning frequency is smaller, the reduction in Q, and RF-induced heating are all significantly reduced when the strip-shield is present. The performance of 800MHz (1)H/(15)N and (1)H/(13)C double-resonance probes is demonstrated on aqueous samples of membrane proteins in phospholipid bilayers.

Single-Pole Double-Throw MMIC Switches for a Microwave Radiometer

NASA Technical Reports Server (NTRS)

Montes, Oliver; Dawson, Douglas E.; Kangaslahti, Pekka P.

2012-01-01

In order to reduce the effect of gain and noise instabilities in the RF chain of a microwave radiometer, a Dicke radiometer topology is often used, as in the case of the proposed surface water and ocean topography (SWOT) radiometer instrument. For this topology, a single-pole double-throw (SPDT) microwave switch is needed, which must have low insertion loss at the radiometer channel frequencies to minimize the overall receiver noise figure. Total power radiometers are limited in accuracy due to the continuous variation in gain of the receiver. High-frequency SPDT switches were developed in the form of monolithic microwave integrated circuits (MMICs) using 75 micron indium phosphide (InP) PIN-diode technology. These switches can be easily integrated into Dicke switched radiometers that utilize microstrip technology.

Double layer-like structures in the core of an argon helicon plasma source with uniform magnetic fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Umair Siddiqui, M., E-mail: musiddiqui@wisc.edu; Hershkowitz, Noah

2014-02-15

A hot (T{sub e} ≈ 10 eV) electron population is observed in the core of a 3 mTorr argon helicon plasma source at 500 W RF power and 900 G uniform axial magnetic field strength, 12 cm from the edge of the helicon antenna. A double layer-like structure consisting of a localized axial electric field of approximately 8 V/cm over 1–2 cm is observed adjacent to the hot electron population. The potential step generated by the electric field is shown to be large enough to trap the hot electrons. To our knowledge this is the first observation of these structures in the core of amore » helicon discharge.« less

RF MEMS and Their Applications in NASA's Space Communication Systems

NASA Technical Reports Server (NTRS)

Williams, W. Daniel; Ponchak, George E.; Simons, Rainee N.; Zaman, Afroz; Kory, Carol; Wintucky, Edwin; Wilson, Jeffrey D.; Scardelletti, Maximilian; Lee, Richard; Nguyen, Hung

2001-01-01

Radio frequency (RF) and microwave communication systems rely on frequency, amplitude, and phase control circuits to efficiently use the available spectrum. Phase control circuits are required for electronically scanning phase array antennas that enable radiation pattern shaping, scanning, and hopping. Two types of phase shifters, which are the phase control circuits, are most often used. The first is comprised of two circuits with different phase characteristics such as two transmission lines of different lengths or a high pass and low pass filter and a switch that directs the RF power through one of the two circuits. Alternatively, a variable capacitor, or varactor, is used to change the effective electrical path length of a transmission line, which changes the phase characteristics. Filter banks are required for the diplexer at the front end of wide band communication satellites. These filters greatly increase the size and mass of the RF/microwave systems, but smaller diplexers may be made with a low loss varactor or a group of capacitors, a switch and an inductor.

Study of Electron Swarm in High Pressure Hydrogen Gas Filled RF Cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yonehara, K.; Chung, M.; Jansson, A.

2010-05-01

A high pressure hydrogen gas filled RF cavity has been proposed for use in the muon collection system for a muon collider. It allows for high electric field gradients in RF cavities located in strong magnetic fields, a condition frequently encountered in a muon cooling channel. In addition, an intense muon beam will generate an electron swarm via the ionization process in the cavity. A large amount of RF power will be consumed into the swarm. We show the results from our studies of the HV RF breakdown in a cavity without a beam and present some results on themore » resulting electron swarm dynamics. This is preliminary to actual beam tests which will take place late in 2010.« less

Slice-selective RF pulses for in vivo B1+ inhomogeneity mitigation at 7 tesla using parallel RF excitation with a 16-element coil.

PubMed

Setsompop, Kawin; Alagappan, Vijayanand; Gagoski, Borjan; Witzel, Thomas; Polimeni, Jonathan; Potthast, Andreas; Hebrank, Franz; Fontius, Ulrich; Schmitt, Franz; Wald, Lawrence L; Adalsteinsson, Elfar

2008-12-01

Slice-selective RF waveforms that mitigate severe B1+ inhomogeneity at 7 Tesla using parallel excitation were designed and validated in a water phantom and human studies on six subjects using a 16-element degenerate stripline array coil driven with a butler matrix to utilize the eight most favorable birdcage modes. The parallel RF waveform design applied magnitude least-squares (MLS) criteria with an optimized k-space excitation trajectory to significantly improve profile uniformity compared to conventional least-squares (LS) designs. Parallel excitation RF pulses designed to excite a uniform in-plane flip angle (FA) with slice selection in the z-direction were demonstrated and compared with conventional sinc-pulse excitation and RF shimming. In all cases, the parallel RF excitation significantly mitigated the effects of inhomogeneous B1+ on the excitation FA. The optimized parallel RF pulses for human B1+ mitigation were only 67% longer than a conventional sinc-based excitation, but significantly outperformed RF shimming. For example the standard deviations (SDs) of the in-plane FA (averaged over six human studies) were 16.7% for conventional sinc excitation, 13.3% for RF shimming, and 7.6% for parallel excitation. This work demonstrates that excitations with parallel RF systems can provide slice selection with spatially uniform FAs at high field strengths with only a small pulse-duration penalty. (c) 2008 Wiley-Liss, Inc.

Workgroup report: base stations and wireless networks-radiofrequency (RF) exposures and health consequences.

PubMed

Valberg, Peter A; van Deventer, T Emilie; Repacholi, Michael H

2007-03-01

Radiofrequency (RF) waves have long been used for different types of information exchange via the air waves--wireless Morse code, radio, television, and wireless telephone (i.e., construction and operation of telephones or telephone systems). Increasingly larger numbers of people rely on mobile telephone technology, and health concerns about the associated RF exposure have been raised, particularly because the mobile phone handset operates in close proximity to the human body, and also because large numbers of base station antennas are required to provide widespread availability of service to large populations. The World Health Organization convened an expert workshop to discuss the current state of cellular-telephone health issues, and this article brings together several of the key points that were addressed. The possibility of RF health effects has been investigated in epidemiology studies of cellular telephone users and workers in RF occupations, in experiments with animals exposed to cell-phone RF, and via biophysical consideration of cell-phone RF electric-field intensity and the effect of RF modulation schemes. As summarized here, these separate avenues of scientific investigation provide little support for adverse health effects arising from RF exposure at levels below current international standards. Moreover, radio and television broadcast waves have exposed populations to RF for > 50 years with little evidence of deleterious health consequences. Despite unavoidable uncertainty, current scientific data are consistent with the conclusion that public exposures to permissible RF levels from mobile telephone and base stations are not likely to adversely affect human health.

Workgroup Report: Base Stations and Wireless Networks—Radiofrequency (RF) Exposures and Health Consequences

PubMed Central

Valberg, Peter A.; van Deventer, T. Emilie; Repacholi, Michael H.

2007-01-01

Radiofrequency (RF) waves have long been used for different types of information exchange via the airwaves—wireless Morse code, radio, television, and wireless telephony (i.e., construction and operation of telephones or telephonic systems). Increasingly larger numbers of people rely on mobile telephone technology, and health concerns about the associated RF exposure have been raised, particularly because the mobile phone handset operates in close proximity to the human body, and also because large numbers of base station antennas are required to provide widespread availability of service to large populations. The World Health Organization convened an expert workshop to discuss the current state of cellular-telephone health issues, and this article brings together several of the key points that were addressed. The possibility of RF health effects has been investigated in epidemiology studies of cellular telephone users and workers in RF occupations, in experiments with animals exposed to cell-phone RF, and via biophysical consideration of cell-phone RF electric-field intensity and the effect of RF modulation schemes. As summarized here, these separate avenues of scientific investigation provide little support for adverse health effects arising from RF exposure at levels below current international standards. Moreover, radio and television broadcast waves have exposed populations to RF for > 50 years with little evidence of deleterious health consequences. Despite unavoidable uncertainty, current scientific data are consistent with the conclusion that public exposures to permissible RF levels from mobile telephony and base stations are not likely to adversely affect human health. PMID:17431492

RF-amide neuropeptides and their receptors in Mammals: Pharmacological properties, drug development and main physiological functions.

PubMed

Quillet, Raphaëlle; Ayachi, Safia; Bihel, Frédéric; Elhabazi, Khadija; Ilien, Brigitte; Simonin, Frédéric

2016-04-01

RF-amide neuropeptides, with their typical Arg-Phe-NH2 signature at their carboxyl C-termini, belong to a lineage of peptides that spans almost the entire life tree. Throughout evolution, RF-amide peptides and their receptors preserved fundamental roles in reproduction and feeding, both in Vertebrates and Invertebrates. The scope of this review is to summarize the current knowledge on the RF-amide systems in Mammals from historical aspects to therapeutic opportunities. Taking advantage of the most recent findings in the field, special focus will be given on molecular and pharmacological properties of RF-amide peptides and their receptors as well as on their implication in the control of different physiological functions including feeding, reproduction and pain. Recent progress on the development of drugs that target RF-amide receptors will also be addressed. Copyright © 2016 Elsevier Inc. All rights reserved.

NQR detection of explosive simulants using RF atomic magnetometers

NASA Astrophysics Data System (ADS)

Monti, Mark C.; Alexson, Dimitri A.; Okamitsu, Jeffrey K.

2016-05-01

Nuclear Quadrupole Resonance (NQR) is a highly selective spectroscopic method that can be used to detect and identify a number of chemicals of interest to the defense, national security, and law enforcement community. In the past, there have been several documented attempts to utilize NQR to detect nitrogen bearing explosives using induction sensors to detect the NQR RF signatures. We present here our work on the NQR detection of explosive simulants using optically pumped RF atomic magnetometers. RF atomic magnetometers can provide an order of magnitude (or more) improvement in sensitivity versus induction sensors and can enable mitigation of RF interference, which has classically has been a problem for conventional NQR using induction sensors. We present the theory of operation of optically pumped RF atomic magnetometers along with the result of laboratory work on the detection of explosive simulant material. An outline of ongoing work will also be presented along with a path for a fieldable detection system.

RF radiation from lightning

NASA Technical Reports Server (NTRS)

Levine, D. M.

1978-01-01

Radiation from lightning in the RF band from 3-300 MHz were monitored. Radiation in this frequency range is of interest as a potential vehicle for monitoring severe storms and for studying the lightning itself. Simultaneous measurements were made of RF radiation and fast and slow field changes. Continuous analogue recordings with a system having 300 kHz of bandwidth were made together with digital records of selected events (principally return strokes) at greater temporal resolution. The data reveal patterns in the RF radiation for the entire flash which are characteristic of flash type and independent of the frequency of observation. Individual events within the flash also have characteristic RF patterns. Strong radiation occurs during the first return strokes, but delayed about 20 micron sec with respect to the begining of the return stroke; whereas, RF radiation from subsequent return strokes tends to be associated with cloud processes preceding the flash with comparatively little radiation occurring during the return stroke itself.

Instantaneous and efficient surface wave excitation of a low pressure gas or gases

DOEpatents

Levy, Donald J.; Berman, Samuel M.

1988-01-01

A system for instantaneously ionizing and continuously delivering energy in the form of surface waves to a low pressure gas or mixture of low pressure gases, comprising a source of rf energy, a discharge container, (such as a fluorescent lamp discharge tube), an rf shield, and a coupling device responsive to rf energy from the source to couple rf energy directly and efficiently to the gas or mixture of gases to ionize at least a portion of the gas or gases and to provide energy to the gas or gases in the form of surface waves. The majority of the rf power is transferred to the gas or gases near the inner surface of the discharge container to efficiently transfer rf energy as excitation energy for at least one of the gases. The most important use of the invention is to provide more efficient fluorescent and/or ultraviolet lamps.

On-Board Fiber-Optic Network Architectures for Radar and Avionics Signal Distribution

NASA Technical Reports Server (NTRS)

Alam, Mohammad F.; Atiquzzaman, Mohammed; Duncan, Bradley B.; Nguyen, Hung; Kunath, Richard

2000-01-01

Continued progress in both civil and military avionics applications is overstressing the capabilities of existing radio-frequency (RF) communication networks based on coaxial cables on board modem aircrafts. Future avionics systems will require high-bandwidth on- board communication links that are lightweight, immune to electromagnetic interference, and highly reliable. Fiber optic communication technology can meet all these challenges in a cost-effective manner. Recently, digital fiber-optic communication systems, where a fiber-optic network acts like a local area network (LAN) for digital data communications, have become a topic of extensive research and development. Although a fiber-optic system can be designed to transport radio-frequency (RF) signals, the digital fiber-optic systems under development today are not capable of transporting microwave and millimeter-wave RF signals used in radar and avionics systems on board an aircraft. Recent advances in fiber optic technology, especially wavelength division multiplexing (WDM), has opened a number of possibilities for designing on-board fiber optic networks, including all-optical networks for radar and avionics RF signal distribution. In this paper, we investigate a number of different novel approaches for fiber-optic transmission of on-board VHF and UHF RF signals using commercial off-the-shelf (COTS) components. The relative merits and demerits of each architecture are discussed, and the suitability of each architecture for particular applications is pointed out. All-optical approaches show better performance than other traditional approaches in terms of signal-to-noise ratio, power consumption, and weight requirements.

On the performance of dual-hop mixed RF/FSO wireless communication system in urban area over aggregated exponentiated Weibull fading channels with pointing errors

NASA Astrophysics Data System (ADS)

Wang, Yue; Wang, Ping; Liu, Xiaoxia; Cao, Tian

2018-03-01

The performance of decode-and-forward dual-hop mixed radio frequency / free-space optical system in urban area is studied. The RF link is modeled by the Nakagami-m distribution and the FSO link is described by the composite exponentiated Weibull (EW) fading channels with nonzero boresight pointing errors (NBPE). For comparison, the ABER results without pointing errors (PE) and those with zero boresight pointing errors (ZBPE) are also provided. The closed-form expression for the average bit error rate (ABER) in RF link is derived with the help of hypergeometric function, and that in FSO link is obtained by Meijer's G and generalized Gauss-Laguerre quadrature functions. Then, the end-to-end ABERs with binary phase shift keying modulation are achieved on the basis of the computed ABER results of RF and FSO links. The end-to-end ABER performance is further analyzed with different Nakagami-m parameters, turbulence strengths, receiver aperture sizes and boresight displacements. The result shows that with ZBPE and NBPE considered, FSO link suffers a severe ABER degradation and becomes the dominant limitation of the mixed RF/FSO system in urban area. However, aperture averaging can bring significant ABER improvement of this system. Monte Carlo simulation is provided to confirm the validity of the analytical ABER expressions.

Beam energy tracking system on Optima XEx high energy ion implanter

DOE Office of Scientific and Technical Information (OSTI.GOV)

David, Jonathan; Satoh, Shu; Wu Xiangyang

2012-11-06

The Axcelis Optima XEx high energy implanter is an RF linac-based implanter with 12 RF resonators for beam acceleration. Even though each acceleration field is an alternating, sinusoidal RF field, the well known phase-focusing principle produces a beam with a sharp quasi-monoenergetic energy spectrum. A magnetic energy filter after the linac further attenuates the low energy continuum in the energy spectrum often associated with RF acceleration. The final beam energy is a function of the phase and amplitude of the 12 resonators in the linac. When tuning a beam, the magnetic energy filter is set to the desired energy, andmore » each linac parameter is tuned to maximize the transmission through the filter. Once a beam is set up, all the parameters are stored in a recipe, which can be easily tuned and has proven to be quite repeatable. The magnetic field setting of the energy filter selects the beam energy from the RF Linac accelerator, and in-situ verification of beam energy in addition to the magnetic energy filter setting has long been desired. An independent energy tracking system was developed for this purpose, using the existing electrostatic beam scanner as a deflector to construct an in-situ electrostatic energy analyzer. This paper will describe the system and performance of the beam energy tracking system.« less

Structural Basis for Bc12-Regulated Mitochondrion-Dependent Apoptosis

DTIC Science & Technology

2005-04-01

groups , double-resonance (’H/15N or 1H/ 31P) probes had square r.f. which have a considerably narrower ’IN chemical shift coils wrapped directly around...bilayers, which provides no res- B E H olution [Fig. 5(D)]. The peak near 35 ppm results from the amino groups of the lysine side-chains and the N...tissue-specific and physiological state-specific sub- 21. Huang Q, Petros AM, Virgin HW, Fesik SW, Olejniczak ET. Proc. units of the Na+, K+-ATPase. The

Nonlinear Optics Technology. Volume 1. Solid State Laser Technology. Phase 3

DTIC Science & Technology

1991-01-12

84 Figure 5.6 Modulator diffraction efficiency as a function of peak power for several 86 RF frequencies Figure 5.7 Thermal effects in the modulator. a...far-field profile of a beam making a 87 double pass through the modulator operating with a peak power of 80 W and average power of 1.6 W. b) same...AU three shown incorporate phase conjugation to provide good beam quality. Figure 1.1a is a standard phase conjugated master oscillator power

Development of a Silicon Metal-Oxide-Semiconductor-Based Qubit Using Spin Exchange Interactions Alone

DTIC Science & Technology

2016-03-31

Electron spin resonance and spin–valley physics in a silicon double quantum dot, Nature Communications, (05 2014): 0. doi: 10.1038/ncomms4860 Ming...new scheme to better manipulate the exchange-only qubit using a pulsed RF source [5], known as a resonant -exchange-qubit [6,7], in GaAs further...triple points into a quadruple point [10], as shown in Fig. 1. We can also gate control the tunnel coupling over a broad energy range. The

Theoretical study of a dual harmonic system and its application to the CSNS/RCS

NASA Astrophysics Data System (ADS)

Yuan, Yao-Shuo; Wang, Na; Xu, Shou-Yan; Yuan, Yue; Wang, Sheng

2015-12-01

Dual harmonic systems have been widely used in high intensity proton synchrotrons to suppress the space charge effect, as well as reduce the beam loss. To investigate the longitudinal beam dynamics in a dual rf system, the potential well, the sub-buckets in the bunch and the multi-solutions of the phase equation are studied theoretically in this paper. Based on these theoretical studies, optimization of bunching factor and rf voltage waveform are made for the dual harmonic rf system in the upgrade phase of the China Spallation Neutron Source Rapid Cycling Synchrotron (CSNS/RCS). In the optimization process, the simulation with space charge effect is done using a newly developed code, C-SCSIM. Supported by National Natural Science Foundation of China (11175193)

Concurrent recording of RF pulses and gradient fields - comprehensive field monitoring for MRI.

PubMed

Brunner, David O; Dietrich, Benjamin E; Çavuşoğlu, Mustafa; Wilm, Bertram J; Schmid, Thomas; Gross, Simon; Barmet, Christoph; Pruessmann, Klaas P

2016-09-01

Reconstruction of MRI data is based on exact knowledge of all magnetic field dynamics, since the interplay of RF and gradient pulses generates the signal, defines the contrast and forms the basis of resolution in spatial and spectral dimensions. Deviations caused by various sources, such as system imperfections, delays, eddy currents, drifts or externally induced fields, can therefore critically limit the accuracy of MRI examinations. This is true especially at ultra-high fields, because many error terms scale with the main field strength, and higher available SNR renders even smaller errors relevant. Higher baseline field also often requires higher acquisition bandwidths and faster signal encoding, increasing hardware demands and the severity of many types of hardware imperfection. To address field imperfections comprehensively, in this work we propose to expand the concept of magnetic field monitoring to also encompass the recording of RF fields. In this way, all dynamic magnetic fields relevant for spin evolution are covered, including low- to audio-frequency magnetic fields as produced by main magnets, gradients and shim systems, as well as RF pulses generated with single- and multiple-channel transmission systems. The proposed approach permits field measurements concurrently with actual MRI procedures on a strict common time base. The combined measurement is achieved with an array of miniaturized field probes that measure low- to audio-frequency fields via (19) F NMR and simultaneously pick up RF pulses in the MRI system's (1) H transmit band. Field recordings can form the basis of system calibration, retrospective correction of imaging data or closed-loop feedback correction, all of which hold potential to render MRI more robust and relax hardware requirements. The proposed approach is demonstrated for a range of imaging methods performed on a 7 T human MRI system, including accelerated multiple-channel RF pulses. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Methodological Preliminaries to the Development of an Expert System for Aerial Photo Interpretation.

DTIC Science & Technology

1984-01-01

Region prl.7.2 Colorado Plateaus Province prl.7.2.1 High Plateaus of Utah Region prl.7.2.2 Uinta Basin Region prl.7.2.3 Canyon Lands Region prI.7.2.4...have a flat to undulating basin --does it?). If a majority of the questions generate negative answers some other hypothesis is sought. % (13) All...rf2.2 Lineaments rf2.3 Troughs -f2.4 Joints f2.5 Escarpments rf2.6 Gorges rfZ.7 Folds Rock Forms 3 Domes Rock Forms 4 Canyons Rock Forms 5 Basins

Communication methods, systems, apparatus, and devices involving RF tag registration

DOEpatents

Burghard, Brion J [W. Richland, WA; Skorpik, James R [Kennewick, WA

2008-04-22

One technique of the present invention includes a number of Radio Frequency (RF) tags that each have a different identifier. Information is broadcast to the tags from an RF tag interrogator. This information corresponds to a maximum quantity of tag response time slots that are available. This maximum quantity may be less than the total number of tags. The tags each select one of the time slots as a function of the information and a random number provided by each respective tag. The different identifiers are transmitted to the interrogator from at least a subset of the RF tags.

Efficient RF energy harvesting by using a fractal structured rectenna system

NASA Astrophysics Data System (ADS)

Oh, Sechang; Ramasamy, Mouli; Varadan, Vijay K.

2014-04-01

A rectenna system delivers, collects, and converts RF energy into direct current to power the electronic devices or recharge batteries. It consists of an antenna for receiving RF power, an input filter for processing energy and impedance matching, a rectifier, an output filter, and a load resistor. However, the conventional rectenna systems have drawback in terms of power generation, as the single resonant frequency of an antenna can generate only low power compared to multiple resonant frequencies. A multi band rectenna system is an optimal solution to generate more power. This paper proposes the design of a novel rectenna system, which involves developing a multi band rectenna with a fractal structured antenna to facilitate an increase in energy harvesting from various sources like Wi-Fi, TV signals, mobile networks and other ambient sources, eliminating the limitation of a single band technique. The usage of fractal antennas effects certain prominent advantages in terms of size and multiple resonances. Even though, a fractal antenna incorporates multiple resonances, controlling the resonant frequencies is an important aspect to generate power from the various desired RF sources. Hence, this paper also describes the design parameters of the fractal antenna and the methods to control the multi band frequency.

Effects of tissue impedance on heat generation during RF delivery with the Thermage system

NASA Astrophysics Data System (ADS)

Tomkoria, Sara; Pope, Karl

2005-04-01

The Thermage ThermaCool TC system is a non-ablative RF device designed to promote tissue tightening and contouring. The system delivers RF energy to a target area under the skin, with volumetric tissue heating in that area. While the amount of energy delivered to a patient can be controlled by ThermaCool system settings, the distribution of energy to the treatment area and underlying layers is variable from individual to individual due to differences in body composition. The present study investigated how local tissue impedance affects the amount of discomfort experienced by patients during RF energy delivery. Discomfort results from heat generation in the treatment area. By using features of the ThermaCool TC System, local impedance (impedance of the treatment area), bulk impedance (impedance of the underlying tissue layers), and total impedance (the sum of local and bulk impedance) were measured for 35 patients. For each patient, impedance measurements were compared to discomfort levels expressed during treatment. Analysis of whole body, local, and bulk impedance values indicate that the percent of total body impedance in the local treatment area contributes to discomfort levels expressed by patients during treatment.

Neurobiological effects of repeated radiofrequency exposures in male senescent rats.

PubMed

Bouji, Marc; Lecomte, Anthony; Gamez, Christelle; Blazy, Kelly; Villégier, Anne-Sophie

2016-11-01

The increasing use of mobile phones by aging people raises issues about the effects of radiofrequency electromagnetic fields (RF-EMF) on the aging central nervous system. Here, we tested if mobile phone RF-EMF exposures could exacerbate senescence-typical neurobiological deficits. Thus, aged (22-24 months) and young (4-6 months) adult male rats were subjected to head RF-EMF exposures (900 MHz, specific absorption rate (SAR) of 6 W/kg, 45 min/day for 1 month in restraint rockets). To assess senescence-typical neurobiological deficits, spatial memory, emotional memory, anxiety-related behavior, locomotor activity, interleukins (IL)-1β and 6, glial fibrillary acidic protein and corticosterone were measured. Aged rats presented deficits in spatial learning, exploration, anxiety-related behaviors, and increased hippocampal ILs and cortical IL-1β. Results showed that senescence-typical neurobiological deficits were not modified by RF-EMF exposures. RF-EMF-exposed rats (young and aged adults pooled) had decreased anxiety-related behaviors in the elevated plus maze. This study which is the first to assess RF-EMF exposures during late aging did not support the hypothesis of a specific cerebral vulnerability to RF-EMF during senescence. More investigations using longer RF-EMF exposures should be performed to conclude regarding the inoffensiveness of RF-EMF exposures.

Integrating a Microwave Radiometer into Radar Hardware for Simultaneous Data Collection Between the Instruments

NASA Technical Reports Server (NTRS)

McLinden, Matthew; Piepmeier, Jeffrey

2013-01-01

The conventional method for integrating a radiometer into radar hardware is to share the RF front end between the instruments, and to have separate IF receivers that take data at separate times. Alternatively, the radar and radiometer could share the antenna through the use of a diplexer, but have completely independent receivers. This novel method shares the radar's RF electronics and digital receiver with the radiometer, while allowing for simultaneous operation of the radar and radiometer. Radars and radiometers, while often having near-identical RF receivers, generally have substantially different IF and baseband receivers. Operation of the two instruments simultaneously is difficult, since airborne radars will pulse at a rate of hundreds of microseconds. Radiometer integration time is typically 10s or 100s of milliseconds. The bandwidth of radar may be 1 to 25 MHz, while a radiometer will have an RF bandwidth of up to a GHz. As such, the conventional method of integrating radar and radiometer hardware is to share the highfrequency RF receiver, but to have separate IF subsystems and digitizers. To avoid corruption of the radiometer data, the radar is turned off during the radiometer dwell time. This method utilizes a modern radar digital receiver to allow simultaneous operation of a radiometer and radar with a shared RF front end and digital receiver. The radiometer signal is coupled out after the first down-conversion stage. From there, the radar transmit frequencies are heavily filtered, and the bands outside the transmit filter are amplified and passed to a detector diode. This diode produces a DC output proportional to the input power. For a conventional radiometer, this level would be digitized. By taking this DC output and mixing it with a system oscillator at 10 MHz, the signal can instead be digitized by a second channel on the radar digital receiver (which typically do not accept DC inputs), and can be down-converted to a DC level again digitally. This unintuitive step allows the digital receiver to sample both the radiometer and radar data at a rapid, synchronized data rate (greater than 1 MHz bandwidth). Once both signals are sampled by the same digital receiver, high-speed quality control can be performed on the radiometer data to allow it to take data simultaneously with the radar. The radiometer data can be blanked during radar transmit, or when the radar return is of a power level high enough to corrupt the radiometer data. Additionally, the receiver protection switches in the RF front end can double as radiometer calibration sources, the short (four-microsecond level) switching periods integrated over many seconds to estimate the radiometer offset. The major benefit of this innovation is that there is minimal impact on the radar performance due to the integration of the radiometer, and the radiometer performance is similarly minimally affected by the radar. As the radar and radiometer are able to operate simultaneously, there is no extended period of integration time loss for the radiometer (maximizing sensitivity), and the radar is able to maintain its full number of pulses (increasing sensitivity and decreasing measurement uncertainty).

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics

NASA Astrophysics Data System (ADS)

Nagayama, Y.; Ito, N.; Kuwahara, D.; Tsuchiya, H.; Yamaguchi, S.

2017-04-01

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 1019 m-3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

Development of 2-D horn-antenna millimeter-wave imaging device (HMID) for the plasma diagnostics.

PubMed

Nagayama, Y; Ito, N; Kuwahara, D; Tsuchiya, H; Yamaguchi, S

2017-04-01

The two-dimensional (2-D) Horn-antenna Millimeter-wave Imaging Device (HMID) has been developed for the O-mode Microwave Imaging Reflectometry (O-MIR) in the Large Helical Device (LHD). The detectable frequency range of the HMID is 23-33 GHz, which corresponds to the cutoff electron density of 0.8-1.5 × 10 19 m -3 in the O-MIR. The HMID is a 2-D imaging device that improves on the horn-antenna mixer array, which had been developed for the X-mode MIR in the LHD. In the HMID, the signal (RF) wave from the horn antenna is transmitted to the microstrip line by the finline transmitter, and this is mixed by the double-balanced-mixer with the local oscillation wave that is fed by a coaxial cable. By using the HMID, the MIR optical system can be significantly simplified.

Laser pumping Cs atom magnetometer of theory research based on gradient tensor measuring

NASA Astrophysics Data System (ADS)

Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

2011-02-01

At present, due to space exploration, military technology, geological exploration, magnetic navigation, medical diagnosis and biological magnetic fields study of the needs of research and development, the magnetometer is given strong driving force. In this paper, it will discuss the theoretical analysis and system design of laser pumping cesium magnetometer, cesium atomic energy level formed hyperfine structure with the I-J coupling, the hyperfine structure has been further split into Zeeman sublevels for the effects of magnetic field. To use laser pump and RF magnetic field make electrons transition in the hyperfine structure to produce the results of magneto-optical double resonance, and ultimately through the resonant frequency will be able to achieve accurate value of the external magnetic field. On this basis, we further have a discussion about magnetic gradient tensor measuring method. To a large extent, it increases the magnetic field measurement of information.

Compact double-bunch x-ray free electron lasers for fresh bunch self-seeding and harmonic lasing

DOE PAGES

Emma, C.; Feng, Y.; Nguyen, D. C.; ...

2017-03-03

This study presents a novel method to improve the longitudinal coherence, efficiency and maximum photon energy of x-ray free electron lasers (XFELs). The method is equivalent to having two separate concatenated XFELs. The first uses one bunch of electrons to reach the saturation regime, generating a high power self-amplified spontaneous emission x-ray pulse at the fundamental and third harmonic. The x-ray pulse is filtered through an attenuator/monochromator and seeds a different electron bunch in the second FEL, using the fundamental and/or third harmonic as an input signal. In our method we combine the two XFELs operating with two bunches, separatedmore » by one or more rf cycles, in the same linear accelerator. We discuss the advantages and applications of the proposed system for present and future XFELs.« less

RF Stealth (Or Low Observable) and Counter- RF Stealth Technologies: Implications of Counter- RF Stealth Solutions for Turkish Air Force

DTIC Science & Technology

2009-03-01

Robotics Coating Facility for Low Observable Material Applications...aircraft. After separation, it would fly to around 78,000 ft altitude and self navigate with its internal Doppler guidance system. If desired, it...lossy magnetic material, with 2 cm of soft rubber , were utilized for purposes of absorbing radar energy and reducing IR signature. Moreover, some tail

High-Fidelity Simulations of Electromagnetic Propagation and RF Communication Systems

DTIC Science & Technology

2017-05-01

addition to high -fidelity RF propagation modeling, lower-fidelity mod- els, which are less computationally burdensome, are available via a C++ API...expensive to perform, requiring roughly one hour of computer time with 36 available cores and ray tracing per- formed by a single high -end GPU...ER D C TR -1 7- 2 Military Engineering Applied Research High -Fidelity Simulations of Electromagnetic Propagation and RF Communication

Thermo-Acoustic Ultrasound for Detection of RF-Induced Device Lead Heating in MRI.

PubMed

Dixit, Neerav; Stang, Pascal P; Pauly, John M; Scott, Greig C

2018-02-01

Patients who have implanted medical devices with long conductive leads are often restricted from receiving MRI scans due to the danger of RF-induced heating near the lead tips. Phantom studies have shown that this heating varies significantly on a case-by-case basis, indicating that many patients with implanted devices can receive clinically useful MRI scans without harm. However, the difficulty of predicting RF-induced lead tip heating prior to scanning prevents numerous implant recipients from being scanned. Here, we demonstrate that thermo-acoustic ultrasound (TAUS) has the potential to be utilized for a pre-scan procedure assessing the risk of RF-induced lead tip heating in MRI. A system was developed to detect TAUS signals by four different TAUS acquisition methods. We then integrated this system with an MRI scanner and detected a peak in RF power absorption near the tip of a model lead when transmitting from the scanner's body coil. We also developed and experimentally validated simulations to characterize the thermo-acoustic signal generated near lead tips. These results indicate that TAUS is a promising method for assessing RF implant safety, and with further development, a TAUS pre-scan could allow many more patients to have access to MRI scans of significant clinical value.

Effects Of Environmental And Operational Stresses On RF MEMS Switch Technologies For Space Applications

NASA Technical Reports Server (NTRS)

Jah, Muzar; Simon, Eric; Sharma, Ashok

2003-01-01

Micro Electro Mechanical Systems (MEMS) have been heralded for their ability to provide tremendous advantages in electronic systems through increased electrical performance, reduced power consumption, and higher levels of device integration with a reduction of board real estate. RF MEMS switch technology offers advantages such as low insertion loss (0.1- 0.5 dB), wide bandwidth (1 GHz-100 GHz), and compatibility with many different process technologies (quartz, high resistivity Si, GaAs) which can replace the use of traditional electronic switches, such as GaAs FETS and PIN Diodes, in microwave systems for low signal power (x < 500 mW) applications. Although the electrical characteristics of RF MEMS switches far surpass any existing technologies, the unknown reliability, due to the lack of information concerning failure modes and mechanisms inherent to MEMS devices, create an obstacle to insertion of MEMS technology into high reliability applications. All MEMS devices are sensitive to moisture and contaminants, issues easily resolved by hermetic or near-hermetic packaging. Two well-known failure modes of RF MEMS switches are charging in the dielectric layer of capacitive membrane switches and contact interface stiction of metal-metal switches. Determining the integrity of MEMS devices when subjected to the shock, vibration, temperature extremes, and radiation of the space environment is necessary to facilitate integration into space systems. This paper will explore the effects of different environmental stresses, operational life cycling, temperature, mechanical shock, and vibration on the first commercially available RF MEMS switches to identify relevant failure modes and mechanisms inherent to these device and packaging schemes for space applications. This paper will also describe RF MEMS Switch technology under development at NASA GSFC.

Human auditory system response to pulsed radiofrequency energy in RF coils for magnetic resonance at 2.4 to 170 MHz.

PubMed

Röschmann, P

1991-10-01

The threshold conditions for an auditory perception of pulsed radiofrequency (RF) energy absorption in the human head have been studied on six volunteers with RF coils for magnetic resonance (MR) imaging. For homogeneous RF exposure with MR head coils in the 2.4- to 170-MHz range and pulse widths 3 microseconds less than or equal to Tp less than 100 microseconds, the auditory thresholds were observed at 16 +/- 4 mJ pulse energy. Localized RF exposure with optimized surface coils positioned flush with the ear lowers the auditory threshold to only 3 +/- 0.6 mJ. The hearing threshold of RF pulses with Tp greater than 200 microseconds occurs at more or less constant peak power levels of typically 150 +/- 50 W for head coils and as low as 20 W for surface coils. The results from this study confirm theoretical predictions from a thermoelastic expansion model and compare well with reported thresholds from near field antenna measurements at 425 to 3000 MHz. Details of the threshold dependence on RF pulse length reveal primary sites of RF to acoustic energy conversion at the mastoid and temporal bone region and the outer layer of the brain from where thermoelastically generated pressure transients excite audible pressure waves at the resonance modes of the skull around 1.7 kHz and of the brain around 11 kHz. If not masked by usually dominating noise from switched gradients, the conditions for hearing RF pulses, as applied to head coils in MR studies with flip angle alpha at main field B0, is given by Tp/ms less than or equal to 0.4 (alpha/pi)B0/[T]. At peak power levels up to 15 kW presently available in clinical MR systems, there is no evidence known for detrimental health effects arising from the RF auditory phenomenon which is a secondary cause associated with primary RF to thermal energy conversion in body tissues. To avoid the RF-evoked sound pressure levels in the head rising above the discomfort threshold at 110 dB SPL, an upper limit of 30 kW applied peak pulse power is suggested for head coils and 6 kW for surface coils.

Design development and testing of high voltage power supply with crowbar protection for IOT based RF amplifier system in VECC

NASA Astrophysics Data System (ADS)

Thakur, S. K.; Kumar, Y.

2018-05-01

This paper described the detailed design, development and testing of high voltage power supply (‑30 kV, 3.2 A) and different power supplies for biasing electrodes of Inductive Output Tube (IOT) based high power Radio Frequency (RF) amplifier. This IOT based RF amplifier is further used for pursuing research and development activity in superconducting RF cavity project at Variable Energy Cyclotron Centre (VECC) Kolkata. The state-of-the-art technology of IOT-based high power RF amplifier is designed, developed, and tested at VECC which is the first of its kind in India. A high voltage power supply rated at negative polarity of 30 kV dc/3.2 A is required for biasing cathode of IOT with crowbar protection circuit. This power supply along with crowbar protection system is designed, developed and tested at VECC for testing the complete setup. The technical difficulties and challenges occured during the design of cathode power supply, its crowbar protection techniques along with other supported power supplies i.e. grid and ion pump power supplies are discussed in this paper.

Vehicle-mounted high-power microwave systems and health risk communication in a deployed environment.

PubMed

Westhoff, John L; Roberts, Brad J; Erickson, Kristin

2013-01-01

Vehicle-mounted high-power microwave systems have been developed to counter the improvised explosive device threat in southwest Asia. Many service members only vaguely comprehend the nature of these devices and the nonionizing radio frequency (RF) radiation they emit. Misconceptions about the health effects of RF radiation have the potential to produce unnecessary anxiety. We report an incident in which concern for exposure to radiation from a high-power microwave device thought to be malfunctioning led to an extensive field investigation, multiple evaluations by clinicians in theater, and subsequent referrals to an Occupational Health clinic upon return from deployment. When acute exposure to RF does occur, the effects are thermally mediated and immediately perceptible--limiting the possibility of injury. Unlike ionizing radiation, RF radiation is not known to cause cancer and the adverse health effects are not cumulative. Medical officers counseling service members concerned about potential RF radiation exposure should apply established principles of risk communication, attend to real and perceived risks, and enlist the assistance of technical experts to properly characterize an exposure when appropriate.

Thermal mechanisms of interaction of radiofrequency energy with biological systems with relevance to exposure guidelines.

PubMed

Foster, Kenneth R; Glaser, Roland

2007-06-01

This article reviews thermal mechanisms of interaction between radiofrequency (RF) fields and biological systems, focusing on theoretical frameworks that are of potential use in setting guidelines for human exposure to RF energy. Several classes of thermal mechanisms are reviewed that depend on the temperature increase or rate of temperature increase and the relevant dosimetric considerations associated with these mechanisms. In addition, attention is drawn to possible molecular and physiological reactions that could be induced by temperature elevations below 0.1 degrees, which are normal physiological responses to heat, and to the so-called microwave auditory effect, which is a physiologically trivial effect resulting from thermally-induced acoustic stimuli. It is suggested that some reported "nonthermal" effects of RF energy may be thermal in nature; also that subtle thermal effects from RF energy exist but have no consequence to health or safety. It is proposed that future revisions of exposure guidelines make more explicit use of thermal models and empirical data on thermal effects in quantifying potential hazards of RF fields.

Reaction of the immune system to low-level RF/MW exposures.

PubMed

Szmigielski, Stanislaw

2013-06-01

Radiofrequency (RF) and microwave (MW) radiation have been used in the modern world for many years. The rapidly increasing use of cellular phones in recent years has seen increased interest in relation to the possible health effects of exposure to RF/MW radiation. In 2011 a group of international experts organized by the IARC (International Agency for Research on Cancer in Lyon) concluded that RF/MW radiations should be listed as a possible carcinogen (group 2B) for humans. The incomplete knowledge of RF/MW-related cancer risks has initiated searches for biological indicators sensitive enough to measure the "weak biological influence" of RF/MWs. One of the main candidates is the immune system, which is able to react in a measurable way to discrete environmental stimuli. In this review, the impacts of weak RF/MW fields, including cell phone radiation, on various immune functions, both in vitro and in vivo, are discussed. The bulk of available evidence clearly indicates that various shifts in the number and/or activity of immunocompetent cells are possible, however the results are inconsistent. For example, a number of lymphocyte functions have been found to be enhanced and weakened within single experiments based on exposure to similar intensities of MW radiation. Certain premises exist which indicate that, in general, short-term exposure to weak MW radiation may temporarily stimulate certain humoral or cellular immune functions, while prolonged irradiation inhibits the same functions. Copyright © 2013. Published by Elsevier B.V.

Radio frequency telemetry system for sensors and actuators

NASA Technical Reports Server (NTRS)

Simons, Rainee N. (Inventor); Miranda, Felix A. (Inventor)

2003-01-01

The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote powering/receiving device. Such technology has many applications, but is especially useful in the biomedical area.

Radio Frequency Telemetry System for Sensors and Actuators

NASA Technical Reports Server (NTRS)

Simons, Rainee N. (Inventor); Miranda, Felix A. (Inventor)

2003-01-01

The present invention discloses and teaches apparatus for combining Radio Frequency (RF) technology with novel micro-inductor antennas and signal processing circuits for RF telemetry of real time, measured data, from microelectromechanical system (MEMS) sensors, through electromagnetic coupling with a remote poweringheceiving device. Such technology has many applications, but is especially useful in the biomedical area.

Performance of mixed RF/FSO systems in exponentiated Weibull distributed channels

NASA Astrophysics Data System (ADS)

Zhao, Jing; Zhao, Shang-Hong; Zhao, Wei-Hu; Liu, Yun; Li, Xuan

2017-12-01

This paper presented the performances of asymmetric mixed radio frequency (RF)/free-space optical (FSO) system with the amplify-and-forward relaying scheme. The RF channel undergoes Nakagami- m channel, and the Exponentiated Weibull distribution is adopted for the FSO component. The mathematical formulas for cumulative distribution function (CDF), probability density function (PDF) and moment generating function (MGF) of equivalent signal-to-noise ratio (SNR) are achieved. According to the end-to-end statistical characteristics, the new analytical expressions of outage probability are obtained. Under various modulation techniques, we derive the average bit-error-rate (BER) based on the Meijer's G function. The evaluation and simulation are provided for the system performance, and the aperture average effect is discussed as well.

An Optical Receiver Post Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administrations (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

An Optical Receiver Post-Processing System for the Integrated Radio and Optical Communications Software Defined Radio Test Bed

NASA Technical Reports Server (NTRS)

Nappier, Jennifer M.; Tokars, Roger P.; Wroblewski, Adam C.

2016-01-01

The Integrated Radio and Optical Communications (iROC) project at the National Aeronautics and Space Administration's (NASA) Glenn Research Center is investigating the feasibility of a hybrid radio frequency (RF) and optical communication system for future deep space missions. As a part of this investigation, a test bed for a radio frequency (RF) and optical software defined radio (SDR) has been built. Receivers and modems for the NASA deep space optical waveform are not commercially available so a custom ground optical receiver system has been built. This paper documents the ground optical receiver, which is used in order to test the RF and optical SDR in a free space optical communications link.

System-Level Integrated Circuit (SLIC) development for phased array antenna applications

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Raquet, C. A.

1991-01-01

A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

System-level integrated circuit (SLIC) development for phased array antenna applications

NASA Technical Reports Server (NTRS)

Shalkhauser, K. A.; Raquet, C. A.

1991-01-01

A microwave/millimeter wave system-level integrated circuit (SLIC) being developed for use in phased array antenna applications is described. The program goal is to design, fabricate, test, and deliver an advanced integrated circuit that merges radio frequency (RF) monolithic microwave integrated circuit (MMIC) technologies with digital, photonic, and analog circuitry that provide control, support, and interface functions. As a whole, the SLIC will offer improvements in RF device performance, uniformity, and stability while enabling accurate, rapid, repeatable control of the RF signal. Furthermore, the SLIC program addresses issues relating to insertion of solid state devices into antenna systems, such as the reduction in number of bias, control, and signal lines. Program goals, approach, and status are discussed.

Neurostimulation systems for deep brain stimulation: in vitro evaluation of magnetic resonance imaging-related heating at 1.5 tesla.

PubMed

Rezai, Ali R; Finelli, Daniel; Nyenhuis, John A; Hrdlicka, Greg; Tkach, Jean; Sharan, Ashwini; Rugieri, Paul; Stypulkowski, Paul H; Shellock, Frank G

2002-03-01

To assess magnetic resonance imaging (MRI)-related heating for a neurostimulation system (Activa Tremor Control System, Medtronic, Minneapolis, MN) used for chronic deep brain stimulation (DBS). Different configurations were evaluated for bilateral neurostimulators (Soletra Model 7426), extensions, and leads to assess worst-case and clinically relevant positioning scenarios. In vitro testing was performed using a 1.5-T/64-MHz MR system and a gel-filled phantom designed to approximate the head and upper torso of a human subject. MRI was conducted using the transmit/receive body and transmit/receive head radio frequency (RF) coils. Various levels of RF energy were applied with the transmit/receive body (whole-body averaged specific absorption rate (SAR); range, 0.98-3.90 W/kg) and transmit/receive head (whole-body averaged SAR; range, 0.07-0.24 W/kg) coils. A fluoroptic thermometry system was used to record temperatures at multiple locations before (1 minute) and during (15 minutes) MRI. Using the body RF coil, the highest temperature changes ranged from 2.5 degrees-25.3 degrees C. Using the head RF coil, the highest temperature changes ranged from 2.3 degrees-7.1 degrees C.Thus, these findings indicated that substantial heating occurs under certain conditions, while others produce relatively minor, physiologically inconsequential temperature increases. The temperature increases were dependent on the type of RF coil, level of SAR used, and how the lead wires were positioned. Notably, the use of clinically relevant positioning techniques for the neurostimulation system and low SARs commonly used for imaging the brain generated little heating. Based on this information, MR safety guidelines are provided. These observations are restricted to the tested neurostimulation system.

Mobile phone base station radiation does not affect neoplastic transformation in BALB/3T3 cells.

PubMed

Hirose, H; Suhara, T; Kaji, N; Sakuma, N; Sekijima, M; Nojima, T; Miyakoshi, J

2008-01-01

A large-scale in vitro study focusing on low-level radiofrequency (RF) fields from mobile radio base stations employing the International Mobile Telecommunication 2000 (IMT-2000) cellular system was conducted to test the hypothesis that modulated RF fields affect malignant transformation or other cellular stress responses. Our group previously reported that DNA strand breaks were not induced in human cells exposed to 2.1425 GHz Wideband Code Division Multiple Access (W-CDMA) radiation up to 800 mW/kg from mobile radio base stations employing the IMT-2000 cellular system. In the current study, BALB/3T3 cells were continuously exposed to 2.1425 GHz W-CDMA RF fields at specific absorption rates (SARs) of 80 and 800 mW/kg for 6 weeks and malignant cell transformation was assessed. In addition, 3-methylcholanthrene (MCA)-treated cells were exposed to RF fields in a similar fashion, to assess for effects on tumor promotion. Finally, the effect of RF fields on tumor co-promotion was assessed in BALB/3T3 cells initiated with MCA and co-exposed to 12-O-tetradecanoylphorbol-13-acetate (TPA). At the end of the incubation period, transformation dishes were fixed, stained with Giemsa, and scored for morphologically transformed foci. No significant differences in transformation frequency were observed between the test groups exposed to RF signals and the sham-exposed negative controls in the non-, MCA-, or MCA plus TPA-treated cells. Our studies found no evidence to support the hypothesis that RF fields may affect malignant transformation. Our results suggest that exposure to low-level RF radiation of up to 800 mW/kg does not induce cell transformation, which causes tumor formation. (c) 2007 Wiley-Liss, Inc.

57. Building 105, another view of ion return RF balance ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

57. Building 105, another view of ion return RF balance tube system, and beginning of waveguide return connections to right of photograph; note bottoms of waveguide systems around circumference of scanner switch in upper part of photograph. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

Design of an RF System for Electron Bernstein Wave Studies in MST

NASA Astrophysics Data System (ADS)

Kauffold, J. X.; Seltzman, A. H.; Anderson, J. K.; Nonn, P. D.; Forest, C. B.

2010-11-01

Motivated by the possibility of current profile control a 5.5GHz RF system for EBW is being developed. The central component is a standard radar Klystron with 1.2MW peak power and 4μs typical pulse length. Meaningful experiments require RF pulse lengths similar to the characteristic electron confinement times in MST necessitating the creation of a power supply providing 80kV at 40A for 10ms. A low inductance IGBT network switches power at 20kHz from an electrolytic capacitor bank into the primary of a three-phase resonant transformer system that is then rectified and filtered. The system uses three magnetically separate transformers with microcrystalline iron cores to provide suitable volt-seconds and low hysteresis losses. Each phase has a secondary with a large leakage inductance and a parallel capacitor providing a boost ratio greater than 60:1 with a physical turns ratio of 13.5:1. A microprocessor feedback control system varies the drive frequency around resonance to regulate the boost ratio and provide a stable output as the storage bank discharges. The completed system will deliver RF to the plasma boundary where coupling to the Bernstein mode and subsequent heating and current drive can occur.

Mutagenic and morphologic impacts of 1.8GHz radiofrequency radiation on human peripheral blood lymphocytes (hPBLs) and possible protective role of pre-treatment with Ginkgo biloba (EGb 761).

PubMed

Esmekaya, Meric Arda; Aytekin, Ebru; Ozgur, Elcin; Güler, Göknur; Ergun, Mehmet Ali; Omeroğlu, Suna; Seyhan, Nesrin

2011-12-01

The mutagenic and morphologic effects of 1.8GHz Global System for Mobile Communications (GSM) modulated RF (radiofrequency) radiation alone and in combination with Ginkgo biloba (EGb 761) pre-treatment in human peripheral blood lymphocytes (hPBLs) were investigated in this study using Sister Chromatid Exchange (SCE) and electron microscopy. Cell viability was assessed with 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay. The lymphocyte cultures were exposed to GSM modulated RF radiation at 1.8GHz for 6, 8, 24 and 48h with and without EGb 761. We observed morphological changes in pulse-modulated RF radiated lymphocytes. Longer exposure periods led to destruction of organelle and nucleus structures. Chromatin change and the loss of mitochondrial crista occurred in cells exposed to RF for 8h and 24h and were more pronounced in cells exposed for 48h. Cytoplasmic lysis and destruction of membrane integrity of cells and nuclei were also seen in 48h RF exposed cells. There was a significant increase (p<0.05) in SCE frequency in RF exposed lymphocytes compared to sham controls. EGb 761 pre-treatment significantly decreased SCE from RF radiation. RF radiation also inhibited cell viability in a time dependent manner. The inhibitory effects of RF radiation on the growth of lymphoctes were marked in longer exposure periods. EGb 761 pre-treatment significantly increased cell viability in RF+EGb 761 treated groups at 8 and 24h when compared to RF exposed groups alone. The results of our study showed that RF radiation affects cell morphology, increases SCE and inhibits cell proliferation. However, EGb 761 has a protective role against RF induced mutagenity. We concluded that RF radiation induces chromosomal damage in hPBLs but this damage may be reduced by EGb 761 pre-treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

Low-cost TDRSS communications for NASA's long duration balloon project

NASA Technical Reports Server (NTRS)

Israel, David J.

1993-01-01

A new transponder and RF ground support equipment for the NASA Tracking and Data Relay Satellite System (TDRSS) intended to support long duration scientific balloon flights in Antarctica are described. The new balloon class transponder features a highly integrated spread spectrum receiver design based on programmable charge coupled device (CCD) correlators and digital signal processing chips. The correlator chip is a Lincoln Labs 4ABC with four CCD channels. The balloon transponder is capable of reporting an estimate of its input bit error rate using digital signal processing. The TDRSS user RF test set is based on a set of RF ground support equipment capable of providing both the RF communications and direct control and monitoring necessary for transponder testing and a two-way RF link for preflight testing.

Efficient Radio Frequency Inductive Discharges in Near Atmospheric Pressure Using Immittance Conversion Topology

NASA Astrophysics Data System (ADS)

Razzak, M. Abdur; Takamura, Shuichi; Uesugi, Yoshihiko; Ohno, Noriyasu

A radio frequency (rf) inductive discharge in atmospheric pressure range requires high voltage in the initial startup phase and high power during the steady state sustainment phase. It is, therefore, necessary to inject high rf power into the plasma ensuring the maximum use of the power source, especially where the rf power is limited. In order to inject the maximum possible rf power into the plasma with a moderate rf power source of few kilowatts range, we employ the immittance conversion topology by converting a constant voltage source into a constant current source to generate efficient rf discharge by inductively coupled plasma (ICP) technique at a gas pressure with up to one atmosphere in argon. A novel T-LCL immittance circuit is designed for constant-current high-power operation, which is practically very important in the high-frequency range, to provide high effective rf power to the plasma. The immittance conversion system combines the static induction transistor (SIT)-based radio frequency (rf) high-power inverter circuit and the immittance conversion elements including the rf induction coil. The basic properties of the immittance circuit are studied by numerical analysis and verified the results by experimental measurements with the inductive plasma as a load at a relatively high rf power of about 4 kW. The performances of the immittance circuit are also evaluated and compared with that of the conventional series resonance circuit in high-pressure induction plasma generation. The experimental results reveal that the immittance conversion circuit confirms injecting higher effective rf power into the plasma as much as three times than that of the series resonance circuit under the same operating conditions and same dc supply voltage to the inverter, thereby enhancing the plasma heating efficiency to generate efficient rf inductive discharges.

UWB multi-burst transmit driver for averaging receivers

DOEpatents

Dallum, Gregory E

2012-11-20

A multi-burst transmitter for ultra-wideband (UWB) communication systems generates a sequence of precisely spaced RF bursts from a single trigger event. There are two oscillators in the transmitter circuit, a gated burst rate oscillator and a gated RF burst or RF power output oscillator. The burst rate oscillator produces a relatively low frequency, i.e., MHz, square wave output for a selected transmit cycle, and drives the RF burst oscillator, which produces RF bursts of much higher frequency, i.e., GHz, during the transmit cycle. The frequency of the burst rate oscillator sets the spacing of the RF burst packets. The first oscillator output passes through a bias driver to the second oscillator. The bias driver conditions, e.g., level shifts, the signal from the first oscillator for input into the second oscillator, and also controls the length of each RF burst. A trigger pulse actuates a timing circuit, formed of a flip-flop and associated reset time delay circuit, that controls the operation of the first oscillator, i.e., how long it oscillates (which defines the transmit cycle).

High output lamp with high brightness

DOEpatents

Kirkpatrick, Douglas A.; Bass, Gary K.; Copsey, Jesse F.; Garber, Jr., William E.; Kwong, Vincent H.; Levin, Izrail; MacLennan, Donald A.; Roy, Robert J.; Steiner, Paul E.; Tsai, Peter; Turner, Brian P.

2002-01-01

An ultra bright, low wattage inductively coupled electrodeless aperture lamp is powered by a solid state RF source in the range of several tens to several hundreds of watts at various frequencies in the range of 400 to 900 MHz. Numerous novel lamp circuits and components are disclosed including a wedding ring shaped coil having one axial and one radial lead, a high accuracy capacitor stack, a high thermal conductivity aperture cup and various other aperture bulb configurations, a coaxial capacitor arrangement, and an integrated coil and capacitor assembly. Numerous novel RF circuits are also disclosed including a high power oscillator circuit with reduced complexity resonant pole configuration, parallel RF power FET transistors with soft gate switching, a continuously variable frequency tuning circuit, a six port directional coupler, an impedance switching RF source, and an RF source with controlled frequency-load characteristics. Numerous novel RF control methods are disclosed including controlled adjustment of the operating frequency to find a resonant frequency and reduce reflected RF power, controlled switching of an impedance switched lamp system, active power control and active gate bias control.

Design and RF measurements of a 5 GHz 500 kW window for the ITER LHCD system

NASA Astrophysics Data System (ADS)

Hillairet, J.; Achard, J.; Bae, Y. S.; Bernard, J. M.; Dechambre, N.; Delpech, L.; Ekedahl, A.; Faure, N.; Goniche, M.; Kim, J.; Larroque, S.; Magne, R.; Marfisi, L.; Namkung, W.; Park, H.; Park, S.; Poli, S.; Vulliez, K.

2014-02-01

CEA/IRFM is conducting R&D efforts in order to validate the critical RF components of the 5 GHz ITER LHCD system, which is expected to transmit 20 MW of RF power to the plasma. Two 5 GHz 500 kW BeO pill-box type window prototypes have been manufactured in 2012 by the PMB Company, in close collaboration with CEA/IRFM. Both windows have been validated at low power, showing good agreement between measured and modeling, with a return loss better than 32 dB and an insertion loss below 0.05 dB. This paper reports on the window RF design and the low power measurements. The high power tests up to 500kW have been carried out in March 2013 in collaboration with NFRI. Results of these tests are also reported.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogacz, Alex

We summarize the current state of a concept for muon acceleration aimed at a future Neutrino Factory and extendable to Higgs Factory. The main thrust of these studies was to reduce the overall cost while maintaining performance by exploring the interplay between the complexity of the cooling systems and the acceptance of the accelerator complex. To ensure adequate survival for the short-lived muons, acceleration must occur at high average gradient. The need for large transverse and longitudinal acceptances drives the design of the acceleration system to an initially low RF frequency, e.g., 325 MHz, which is then increased to 650more » MHz as the transverse size shrinks with increasing energy. High-gradient normal conducting RF cavities at these frequencies require extremely high peak-power RF sources. Hence superconducting RF (SRF) cavities are chosen. We consider an SRF-efficient design based on a multi-pass (4.5) ?dogbone? RLA, extendable to multi-pass FFAG-like arcs.« less

Radio frequency cavity analysis, measurement, and calibration of absolute Dee voltage for K-500 superconducting cyclotron at VECC, Kolkata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Som, Sumit; Seth, Sudeshna; Mandal, Aditya

2013-02-15

Variable Energy Cyclotron Centre has commissioned a K-500 superconducting cyclotron for various types of nuclear physics experiments. The 3-phase radio-frequency system of superconducting cyclotron has been developed in the frequency range 9-27 MHz with amplitude and phase stability of 100 ppm and {+-}0.2{sup 0}, respectively. The analysis of the RF cavity has been carried out using 3D Computer Simulation Technology (CST) Microwave Studio code and various RF parameters and accelerating voltages ('Dee' voltage) are calculated from simulation. During the RF system commissioning, measurement of different RF parameters has been done and absolute Dee voltage has been calibrated using a CdTemore » X-ray detector along with its accessories and known X-ray source. The present paper discusses about the measured data and the simulation result.« less

Electromagnetic coupling to centimeter-scale mechanical membrane resonators via RF cylindrical cavities

NASA Astrophysics Data System (ADS)

Martinez, Luis A.; Castelli, Alessandro R.; Delmas, William; Sharping, Jay E.; Chiao, Raymond

2016-11-01

We present experimental and theoretical results for the excitation of a mechanical oscillator via radiation pressure with a room-temperature system employing a relatively low-(Q) centimeter-size mechanical oscillator coupled to a relatively low-Q standard three-dimensional radio-frequency (RF) cavity resonator. We describe the forces giving rise to optomechanical coupling using the Maxwell stress tensor and show that nanometer-scale displacements are possible and experimentally observable. The experimental system is composed of a 35 mm diameter silicon nitride membrane sputtered with a 300 nm gold conducting film and attached to the end of a RF copper cylindrical cavity. The RF cavity is operated in its {{TE}}011 mode and amplitude modulated on resonance with the fundamental drum modes of the membrane. Membrane motion is monitored using an unbalanced, non-zero optical path difference, optically filtered Michelson interferometer capable of measuring sub-nanometer displacements.

Design of 6 MeV X-band electron linac for dual-head gantry radiotherapy system

NASA Astrophysics Data System (ADS)

Shin, Seung-wook; Lee, Seung-Hyun; Lee, Jong-Chul; Kim, Huisu; Ha, Donghyup; Ghergherehchi, Mitra; Chai, Jongseo; Lee, Byung-no; Chae, Moonsik

2017-12-01

A compact 6 MeV electron linac is being developed at Sungkyunkwan University, in collaboration with the Korea atomic energy research institute (KAERI). The linac will be used as an X-ray source for a dual-head gantry radiotherapy system. X-band technology has been employed to satisfy the size requirement of the dual-head gantry radiotherapy machine. Among the several options available, we selected a pi/2-mode, standing-wave, side-coupled cavity. This choice of radiofrequency (RF) cavity design is intended to enhance the shunt impedance of each cavity in the linac. An optimum structure of the RF cavity with a high-performance design was determined by applying a genetic algorithm during the optimization procedure. This paper describes the detailed design process for a single normal RF cavity and the entire structure, including the RF power coupler and coupling cavity, as well as the beam dynamics results.

RF-photonic chirp encoder and compressor for seamless analysis of information flow.

PubMed

Zalevsky, Zeev; Shemer, Amir; Zach, Shlomo

2008-05-26

In this paper we realize an RF photonic chirp compression system that compresses a continuous stream of incoming RF data (modulated on top of an optical carrier) into a train of temporal short pulses. Each pulse in the train can be separated and treated individually while being sampled by low rate optical switch and without temporal loses of the incoming flow of information. Each such pulse can be filtered and analyzed differently. The main advantage of the proposed system is its capability of being able to handle, seamlessly, high rate information flow with all-optical means and with low rate optical switches.

Decoupling PI Controller Design for a Normal Conducting RF Cavity Using a Recursive LEVENBERG-MARQUARDT Algorithm

NASA Astrophysics Data System (ADS)

Kwon, Sung-il; Lynch, M.; Prokop, M.

2005-02-01

This paper addresses the system identification and the decoupling PI controller design for a normal conducting RF cavity. Based on the open-loop measurement data of an SNS DTL cavity, the open-loop system's bandwidths and loop time delays are estimated by using batched least square. With the identified system, a PI controller is designed in such a way that it suppresses the time varying klystron droop and decouples the In-phase and Quadrature of the cavity field. The Levenberg-Marquardt algorithm is applied for nonlinear least squares to obtain the optimal PI controller parameters. The tuned PI controller gains are downloaded to the low-level RF system by using channel access. The experiment of the closed-loop system is performed and the performance is investigated. The proposed tuning method is running automatically in real time interface between a host computer with controller hardware through ActiveX Channel Access.

Test results of 3.7 GHz 500kW CW klystron for SST1 LHCD system

NASA Astrophysics Data System (ADS)

Sharma, Promod Kumar; Ambulkar, Kiran K.; Dalakoti, Shefali; Rajan Babu, N.; Parmar, Pramod R.; Virani, Chetan G.; Thakur, Arvind L.

2012-10-01

A 3.7 GHz, LHCD system aims to driving non inductive plasma current for SST1 machine. Its capability has been enhanced up to 2 MW by adding two additional klystrons, each rated for 500kW, CW power. The additional klystrons are installed and commissioned at site, for rated power, for more than 1000 seconds, before connecting them to main LHCD system. The auxiliary systems, like supporting power supply system (magnet, filament, ion pump, etc.), active heat management system, slow and fast interlock system, transmission line pressurization system, low power rf drive system, etc. are inter-connected with klystron system through VME based data acquisition and control system for remote CW operation of klystron at rated power. The calorimetric measurements, employing Pt-100 sensors, suggests that the maximum rf power (˜500kW CW) extracted from klystron is dissipated on water cooled dummy loads. The unspent DC power (˜800 kW CW) is dissipated in collector which is heavily cooled with water flowing at ˜1300 litres/min (lpm). The power loss in the klystron body remained within 20 kW. The cavity temperature, measured using J-type thermocouple, remained below 150 ^oC. The output rf power, sampled through directional couplers and measured by rf detectors shows good agreement with calorimetric measurements. A detailed description of the klystron test set up and the test results obtained during its commissioning is presented in this paper.

Development of an automatic frequency control system for an X-band (=9300 MHz) RF electron linear accelerator

NASA Astrophysics Data System (ADS)

Cha, Sungsu; Kim, Yujong; Lee, Byung Cheol; Park, Hyung Dal; Lee, Seung Hyun; Buaphad, Pikad

2017-05-01

KAERI is developing a 6 MeV X-band radio frequency (RF) electron linear accelerator for medical purposes. The proposed X-band accelerator consists of an e-gun, an accelerating structure, two solenoid magnets, two steering magnets, a magnetron, a modulator, and an automatic frequency control (AFC) system. The accelerating structure of the component consists of oxygen-free high-conductivity copper (OFHC). Therefore, the ambient temperature changes the volume, and the resonance frequency of the accelerating structure also changes. If the RF frequency of a 9300 MHz magnetron and the resonance frequency of the accelerating structure do not match, it can degrade the performance. That is, it will decrease the output power, lower the beam current, decrease the X-ray dose rate, increase the reflection power, and result in unstable operation of the accelerator. Accelerator operation should be possible at any time during all four seasons. To prevent humans from being exposed to radiation when it is operated, the accelerator should also be operable through remote monitoring and remote control. Therefore, the AFC system is designed to meet these requirements; it is configured based on the concept of a phase-locked loop (PLL) model, which includes an RF section, an intermediate frequency (IF) [1-3] section, and a local oscillator (LO) section. Some resonance frequency controllers use a DC motor, chain, and potentiometer to store the position and tune the frequency [4,5]. Our AFC system uses a step motor to tune the RF frequency of the magnetron. The maximum tuning turn number of our magnetron frequency tuning shaft is ten. Since the RF frequency of our magnetron is 9300±25 MHz, it gives 5 MHz (∵±25 MHz/10 turns → 50 MHz/10 turns =5 MHz/turn) frequency tuning per turn. The rotation angle of our step motor is 0.72° per step and the total step number per one rotation is 360°/0.72°=500 steps. Therefore, the tuning range per step is 10 kHz/step (=5 MHz per turn/500 steps per turn). The developed system is a more compact new resonance frequency control system. In addition, a frequency measuring part is included and it can measure the real-time resonance frequency from the magnetron. We have succeeded in the stable provisioning of RF power by recording the results of a 0.01% frequency deviation in the AFC during an RF test. Accordingly, in this paper, the detailed design, fabrication, and a high power test of the AFC system for the X-band linac are presented.

The state of technology in electromagnetic (RF) sensors (for lightning detection)

NASA Technical Reports Server (NTRS)

Shumpert, T. H.; Honnell, M. A.

1979-01-01

A brief overview of the radio-frequency sensors which were applied to the detection, isolation, and/or identification of the transient electromagnetic energy (sferics) radiated from one or more lightning discharges in the atmosphere is presented. Radio frequency (RF) characteristics of lightning discharges, general RF sensor (antenna) characteristics, sensors and systems previously used for sferic detection, electromagnetic pulse sensors are discussed. References containing extensive bibliographies concerning lightning are presented.

Deployed Communications in an Austere Environment: A Delphi Study

DTIC Science & Technology

2013-12-01

gateways to access the Global Information Grid ( GIG ) will escalate dramatically. The ability simply to “deploy” a unit similar to the RF- SATCOM network...experts had divergent views on how deployed communications systems would link back to the GIG . The scenario uses both projected technologies. First...the self-configuring RF-SATCOM network link acts as a gateway to the GIG , providing wireless RF connectivity to autho- rized devices within the area

Petroleum taxation: a comparison between Russia and Kazakhstan

NASA Astrophysics Data System (ADS)

Tsibulnikova, M. R.; Salata, D. V.; Drebot, V. V.; Vorozheykina, E. A.

2016-09-01

The paper compares mineral resource recovery taxes for oil to be paid in Kazakhstan and the RF. It provides a case study on an average Kazakh oil and gas company and presents tax calculations as an example. To compare the taxation systems in Kazakhstan and the RF, the situation is modelled as if the field was located in the RF and the relevant calculations are carried out in compliance with national laws and regulations.

Laboratory Directed Research and Development Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

Laboratory Directed Research and Development Program. Annual report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogeka, G.J.; Romano, A.J.

This report briefly discusses the following research: Advances in Geoexploration; Transvenous Coronary Angiography with Synchrotron X-Rays; Borehole Measurements of Global Warming; Molecular Ecology: Development of Field Methods for Microbial Growth Rate and Activity Measurements; A New Malaria Enzyme - A Potential Source for a New Diagnostic Test for Malaria and a Target for a New Antimalarial Drug; Basic Studies on Thoron and Thoron Precursors; Cloning of the cDNA for a Human Serine/Threonine Protein Kinase that is Activated Specifically by Double-Stranded DNA; Development of an Ultra-Fast Laser System for Accelerator Applications; Cluster Impact Fusion; Effect of a Bacterial Spore Protein onmore » Mutagenesis; Structure and Function of Adenovirus Penton Base Protein; High Resolution Fast X-Ray Detector; Coherent Synchrotron Radiation Longitudinal Bunch Shape Monitor; High Grain Harmonic Generation Experiment; BNL Maglev Studies; Structural Investigations of Pt-Based Catalysts; Studies on the Cellular Toxicity of Cocaine and Cocaethylene; Human Melanocyte Transformation; Exploratory Applications of X-Ray Microscopy; Determination of the Higher Ordered Structure of Eukaryotic Chromosomes; Uranium Neutron Capture Therapy; Tunneling Microscopy Studies of Nanoscale Structures; Nuclear Techiques for Study of Biological Channels; RF Sources for Accelerator Physics; Induction and Repair of Double-Strand Breaks in the DNA of Human Lymphocytes; and An EBIS Source of High Charge State Ions up to Uranium.« less

The LLRF System for the S-Band RF Plants of the FERMI Linac

NASA Astrophysics Data System (ADS)

Fabris, A.; Byrd, J.; D'Auria, G.; Doolittle, L.; Gelmetti, F.; Huang, G.; Jones, J.; Milloch, M.; Predonzani, M.; Ratti, A.; Rohlev, T.; Salom, A.; Serrano, C.; Stettler, M.

2016-04-01

Specifications on electron beam quality for the operation of a linac-based free-electron laser (FEL), as FERMI in Trieste (Italy), impose stringent requirements on the stability of the electromagnetic fields of the accelerating sections. These specifications can be met only with state-of-the-art low-level RF (LLRF) systems based on advanced digital technologies. Design considerations, construction, and performance results of the FERMI digital LLRF are presented in this paper. The stability requirements derived by simulations are better than 0.1% in amplitude and 0.1° S-band in phase. The system installed in the FERMI Linac S-band RF plants has met these specifications and is in operation on a 24-h basis as a user facility. Capabilities of the system allow planning for new developments that are also described here.

RF-subcarrier-assisted four-state continuous-variable QKD based on coherent detection.

PubMed

Qu, Zhen; Djordjevic, Ivan B; Neifeld, Mark A

2016-12-01

We theoretically investigate and experimentally demonstrate a RF-assisted four-state continuous-variable quantum key distribution (CV-QKD) system. Classical coherent detection is implemented with a simple digital phase noise cancelation scheme. In the proposed system, there is no need for frequency and phase locking between the quantum signals and the local oscillator laser. Moreover, in principle, there is no residual phase noise, and a mean excess noise of 0.0115 (in shot-noise units) can be acquired experimentally. In addition, the minimum transmittance of 0.45 is reached experimentally for secure transmission with commercial photodetectors, and the maximum secret key rate (SKR) of >12  Mbit/s can be obtained. The proposed RF-assisted CV-QKD system opens the door of incorporating microwave photonics into a CV-QKD system and improving the SKR significantly.

Dry etch challenges for CD shrinkage in memory process

NASA Astrophysics Data System (ADS)

Matsushita, Takaya; Matsumoto, Takanori; Mukai, Hidefumi; Kyoh, Suigen; Hashimoto, Kohji

2015-03-01

Line pattern collapse attracts attention as a new problem of the L&S formation in sub-20nm H.P feature. Line pattern collapse that occurs in a slight non-uniformity of adjacent CD (Critical dimension) space using double patterning process has been studied with focus on micro-loading effect in Si etching. Bias RF pulsing plasma etching process using low duty cycle helped increase of selectivity Si to SiO2. In addition to the effect of Bias RF pulsing process, the thin mask obtained from improvement of selectivity has greatly suppressed micro-loading in Si etching. However it was found that micro-loading effect worsen again in sub-20nm space width. It has been confirmed that by using cycle etch process to remove deposition with CFx based etching micro-loading effect could be suppressed. Finally, Si etching process condition using combination of results above could provide finer line and space without "line pattern collapse" in sub-20nm.

Refractory organic matter in coastal salt marshes-effect on C sequestration calculations.

PubMed

Leorri, Eduardo; Zimmerman, Andrew R; Mitra, Siddhartha; Christian, Robert R; Fatela, Francisco; Mallinson, David J

2018-08-15

The age and ability of salt marshes to accumulate and sequester carbon is often assessed using the carbon isotopic signatures (Δ 14 C and δ 13 C) of sedimentary organic matter. However, transfers of allochthonous refractory carbon (C RF ) from the watershed to marshes would not represent new C sequestration. To better understand how refractory carbon (C RF ) inputs affect assessments of marsh age and C sequestration, Δ 14 C and δ 13 C of both total organic carbon (TOC), C RF , and non-C RF organic matter fractions were measured in salt marshes from four contrasting systems on the North Atlantic coast. To our knowledge, no salt marsh sediment study has considered refractory or allochthonous carbon in carbon budget calculations or the impact on chronologies. Stable and radiogenic isotope data suggest that while TOC was dominated by autochthonous plant inputs, C RF was dominated by locally recycled or allochthonous C, the delivery of which was controlled by the size and slope of each watershed. Steep-gradient rivers analyzed delivered Δ 14 C-depleted C RF to their estuarine marshes, while the site located in the low-gradient river was associated with larger C RF content. Finally, the marsh isolated from riverine input contained the least fraction of TOC as C RF . Laterally transported C RF caused only a small offset in Δ 14 C in relation to TOC in low-gradient systems (average Δ 14 C offset was -44.4 and -24.2‰ at each location). However, the presence of allochthonous Δ 14 C-depleted C RF in sediments of steep-gradient rivers led to large overestimates of the time of organic matter deposition (i.e. apparent age was older than the 'true' time of deposition) (Δ 14 C offset ranged from -170.6 to -528.9‰). Further, reliance on TOC or loss on ignition analyses to calculate C sequestration by marshes might produce overestimates of at least as much as 10 to 20% since neither account for the lateral transport of allochthonous carbon. Copyright © 2018 Elsevier B.V. All rights reserved.

SU-F-J-142: Proposed Method to Broaden Inclusion Potential of Patients Able to Use the Calypso Tracking System in Prostate Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fiedler, D; Kuo, H; Bodner, W

2016-06-15

Purpose: To introduce a non-standard method of patient setup, using BellyBoard immobilization, to better utilize the localization and tracking potential of an RF-beacon system with EBRT for prostate cancer. Methods: An RF-beacon phantom was imaged using a wide bore CT scanner, both in a standard level position and with a known rotation (4° pitch and 7.5° yaw). A commercial treatment planning system (TPS) was used to determine positional coordinates of each beacon, and the centroid of the three beacons for both setups. For each setup at the Linac, kV AP and Rt Lateral images were obtained. A full characterization ofmore » the RF-beacon system in clinical mode was completed for various beacons’ array-to-centroid distances, which includes vertical, lateral, and longitudinal offset data, as well as pitch and yaw offset measurements for the tilted phantom. For the single patient who has been setup using the proposed BellyBoard method, a supine simulation was first obtained. When abdominal protrusion was found to be exceeding the limits of the RF-Beacon system through distance-based analysis in the TPS, the patient is re-simulated prone with the BellyBoard. Array to centroid distance is measured again in the TPS, and if found to be within the localization or tracking region it is applied. Results: Characterization of limitations for the RF-beacon system in clinical mode showed acceptable consistency of offset determination for phantom setup accuracy. The nonstandard patient setup method reduced the beacons’ centroid-to-array distance by 8.32cm, from 25.13cm to 16.81cm; completely out of tracking range (greater than 20cm) to within setup tracking range (less than 20cm). Conclusion: Using the RF-beacon system in combination with this novel patient setup can allow patients who would otherwise not be candidates for beacon enhanced EBRT to now be able to benefit from the reduced PTV margins of this treatment method.« less

Effects of doping concentration ratio on electrical characterization in pseudomorphic HEMT-based MMIC switches for ICT system

NASA Astrophysics Data System (ADS)

Mun, Jae-Kyoung; Oh, Jung-Hun; Sung, Ho-Kun; Wang, Cong

2015-12-01

The effects of the doping concentration ratios between upper and lower silicon planar-doping layers on the DC and RF characteristics of the double planar doped pseudomorphic high electron mobility transistors (pHEMTs) are investigated. From the device simulation, an increase of maximum extrinsic transconductance and a decrease of total on- and off-state capacitances are observed, as well as an increase of the upper to lower planar-doping concentration ratios (UTLPDR), which give rise to an enhancement of the switching speed and isolation characteristics. On the basis of simulation results, two types of pHEMTs are fabricated with two different UTLPDRs of 4:1 and 1:2. After applying these two types' pHEMTs, single-pole-double-throw (SPDT) transmitter/receiver monolithic microwave integrated circuit (MMIC) switches are also designed and fabricated. The SPDT MMIC switch with a 4:1 UTLPDR shows an insertion loss of 0.58 dB, isolation of 40.2 dB, and switching speed of 100 ns, respectively, which correspondingly indicate a 0.23 dB lower insertion loss, 2.90 dB higher isolation and 2.5 times faster switching speed than those of 1:2 UTLPDR at frequency range of 2-6 GHz. From the simulation results and comparative studies, we propose that the UTLPDR must be greater than 4:1 for the best switching performance. With the abovementioned excellent performances, the proposed switch would be quite promising in the application of information and communications technology system.

Evaluation of a role functioning computer adaptive test (RF-CAT).

PubMed

Anatchkova, M; Rose, M; Ware, J; Bjorner, J B

2013-06-01

To evaluate the validity and participants' acceptance of an online assessment of role function using computer adaptive test (RF-CAT). The RF-CAT and a set of established quality of life instruments were administered in a cross-sectional study in a panel sample (n = 444) recruited from the general population with over-selection of participants with selected self-report chronic conditions (n = 225). The efficiency, score accuracy, validity, and acceptability of the RF-CAT were evaluated and compared to existing measures. The RF-CAT with a stopping rule of six items with content balancing used 25 of the available bank items and was completed on average in 66 s. RF-CAT and the legacy tools scores were highly correlated (.64-.84) and successfully discriminated across known groups. The RF-CAT produced a more precise assessment over a wider range than the SF-36 Role Physical scale. Patients' evaluations of the RF-CAT system were positive overall, with no differences in ratings observed between the CAT and static assessments. The RF-CAT was feasible, more precise than the static SF-36 RP and equally acceptable to participants as legacy measures. In empirical tests of validity, the better performance of the CAT was not uniformly statistically significant. Further research exploring the relationship between gained precision and discriminant power of the CAT assessment is needed.

FPGA-based RF spectrum merging and adaptive hopset selection

NASA Astrophysics Data System (ADS)

McLean, R. K.; Flatley, B. N.; Silvius, M. D.; Hopkinson, K. M.

The radio frequency (RF) spectrum is a limited resource. Spectrum allotment disputes stem from this scarcity as many radio devices are confined to a fixed frequency or frequency sequence. One alternative is to incorporate cognition within a reconfigurable radio platform, therefore enabling the radio to adapt to dynamic RF spectrum environments. In this way, the radio is able to actively sense the RF spectrum, decide, and act accordingly, thereby sharing the spectrum and operating in more flexible manner. In this paper, we present a novel solution for merging many distributed RF spectrum maps into one map and for subsequently creating an adaptive hopset. We also provide an example of our system in operation, the result of which is a pseudorandom adaptive hopset. The paper then presents a novel hardware design for the frequency merger and adaptive hopset selector, both of which are written in VHDL and implemented as a custom IP core on an FPGA-based embedded system using the Xilinx Embedded Development Kit (EDK) software tool. The design of the custom IP core is optimized for area, and it can process a high-volume digital input via a low-latency circuit architecture. The complete embedded system includes the Xilinx PowerPC microprocessor, UART serial connection, and compact flash memory card IP cores, and our custom map merging/hopset selection IP core, all of which are targeted to the Virtex IV FPGA. This system is then incorporated into a cognitive radio prototype on a Rice University Wireless Open Access Research Platform (WARP) reconfigurable radio.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ryan, Philip Michael; Ahn, Joonwook; Bell, R. E.

High-harmonic fast wave (HHFW) heating and current drive is being developed in NSTX to provide bulk electron heating and q(0) control during non-inductively sustained Hmode plasmas fuelled by deuterium neutral-beam injection (NBI). In addition, it is used to assist the plasma current ramp-up. A major modification to increase the RF power limit was made in 2009; the original end-grounded, single end-powered current straps of the 12- element array were replaced with center-grounded, double end-powered straps. Greater than 3 MW have been coupled into NBI-driven, ELMy H-mode plasmas with this upgraded antenna. Improved core HHFW heating, particularly at longer wavelengths andmore » during low-density start-up and plasma current ramp-up, has been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for fast-wave propagation away from the vessel wall [1]. Significant core electron heating of NBI-fuelled H-modes has been observed for the first time over a range of launched wavelengths and H-modes can be accessed by HHFW alone. Visible and IR camera images of the antenna and divertor indicate that fast wave interactions can deposit considerable RF energy on the outboard divertor plate, especially at longer wavelengths that begin to propagate closer to the vessel walls. Edge power loss can also arise from HHFWgenerated parametric decay instabilities; edge ion heating is observed that is wavelength dependent. During plasmas where HHFW is combined with NBI, there is a significant enhancement in neutron rate, and fast-ion D-alpha (FIDA) emission measurements clearly show broadening of the fast-ion profile in the plasma core. Large edge localized modes (ELMs) have been observed immediately following the termination of RF power, whether the power turn off is programmed or due to antenna arcing. Causality has not been established but new experiments are planned and will be reported. Fast digitization of the reflected power signal indicates a much faster rise time for arcs than for ELMs. Based on this observation, an ELM/arc discrimination system is being implemented to maintain RF power during ELMs even when the reflection coefficient becomes large. This work is supported by US DOE contracts DE-AC-05-00OR22725 and DE-AC02- 09CH11466. References [1] C. K. Phillips, et al, Nuclear Fusion 10, 075015 (2009)« less