A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals

NASA Astrophysics Data System (ADS)

Bakir, A.; Rocher, C.; Maréchal, B.; Bigler, E.; Boudot, R.; Kersalé, Y.; Millo, J.

2018-05-01

We report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10-14 at 1 s integration time and in the low 10-16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz-1 GHz range.

A pilot study of the efficacy of the POLARGEN® ultrahigh-frequency electric field (40.68 MHz) radiofrequency device in the treatment of facial contouring.

PubMed

Kim, Miri; Lim, Jihong; Bae, Jung Min; Park, Hyun Jeong

2017-11-01

Various radiofrequency (RF) devices are used to treat skin laxity and face contouring, but few studies have examined ultrahigh-frequency (UHF) electric field (40.68 MHz) RF devices. To evaluate the efficacy and safety of a UHF electric field (40.68 MHz) RF device for skin tightening and face contouring. Ten patients each underwent four sessions of UHF electric field RF device treatment at 2-week intervals. Clinical improvement was evaluated with the patient satisfaction score using a six-point scale, and clinical photographs taken at every visit and 2 months after the RF treatment were assessed. Skin biopsies were obtained from one patient before the first treatment and immediately after the last treatment. Adverse reactions were recorded at every follow-up visit. All patients were women with a mean age of 51.7 ± 7.2 years. The mean satisfaction score was 4.5 ± 0.9 immediately after the last treatment session. Cheek, jawline, and neck enhancement and tightening were apparent in all patients. Side effects were minimal, and there were no burns or major complications. The UHF electric field RF device was effective for skin tightening and facial contouring, without significant adverse reactions.

Radiation hardness of Efratom M-100 rubidium frequency standard

NASA Technical Reports Server (NTRS)

English, T. C.; Vorwerk, H.; Rudie, N. J.

1983-01-01

The effects of nuclear radiation on rubidium gas cell frequency standards and components are presented, including the results of recent tests where a continuously operating rubidium frequency standard (Effratom, Model M-100) was subjected to simultaneous neutron/gamma radiation. At the highest neutron fluence 7.5 10 to the 12th power n/sq cm and total dose 11 krad(Si) tested, the unit operated satisfactorily; the total frequency change over the 2 1/2 hour test period due to all causes, including repeated retraction from and insertion into the reactor, was less than 1 x 10 to the -10th power. The effects of combined neutron/gamma radiation on rubidium frequency standard physics package components were also studied, and the results are presented.

Ultrahigh-frequency ultrasound of fascicles in the median nerve at the wrist.

PubMed

Cartwright, Michael S; Baute, Vanessa; Caress, James B; Walker, Francis O

2017-10-01

An ultrahigh-frequency (70 MHZ) ultrasound device has recently been approved for human use. This study seeks to determine whether this device facilitates counting of fascicles within the median nerve at the wrist. Twenty healthy volunteers underwent imaging of the median nerve at the wrist bilaterally. The number of fascicles in each nerve was counted by two independent raters. The mean fascicle number was 22.68. Correlation was strong between the two raters (r = 0.68, P < 0.001). Age, sex, body mass index, and nerve area did not predict fascicle number. Those with bifid median nerves and persistent median arteries had lower fascicle density than those without anatomic anomalies (1.79 vs. 2.29; P = 0.01). Fascicles within the median nerve at the wrist can be readily imaged. Ultrahigh-frequency ultrasound technology may be informative in a variety of disorders affecting the peripheral nervous system. Muscle Nerve 56: 819-822, 2017. © 2017 Wiley Periodicals, Inc.

The Radio Background below 100 MHz

NASA Astrophysics Data System (ADS)

Dowell, Jayce; Taylor, Greg B.

2018-05-01

The recent detection of the “cosmic dawn” redshifted 21 cm signal at 78 MHz by the Experiment to Detect the Global EoR Signatures (EDGES) differs significantly from theoretical predictions. In particular, the absorption trough is roughly a factor of two stronger than the most optimistic theoretical models. The early interpretations of the origin of this discrepancy fall into two categories. The first is that there is increased cooling of the gas due to interactions with dark matter, while the second is that the background radiation field includes a contribution from a component in addition to the cosmic microwave background (CMB). In this Letter we examine the feasibility of the second idea using new data from the first station of the Long Wavelength Array. The data span 40–80 MHz and provide important constraints on the present-day background in a frequency range where there are few surveys with absolute temperature calibration suitable for measuring the strength of the radio monopole. We find support for a strong, diffuse radio background that was suggested by the ARCARDE 2 results in the 3–10 GHz range. We find that this background is well modeled by a power law with a spectral index of ‑2.58 ± 0.05 and a temperature at the rest frame 21 cm frequency of {603}-92+102 mK.

100 MHz high-speed strain monitor using fiber Bragg grating and optical filter applied for magnetostriction measurements of cobaltite at magnetic fields beyond 100 T

NASA Astrophysics Data System (ADS)

Ikeda, Akihiko; Nomura, Toshihiro; Matsuda, Yasuhiro H.; Tani, Shuntaro; Kobayashi, Yohei; Watanabe, Hiroshi; Sato, Keisuke

2018-05-01

High-speed 100 MHz strain monitor using fiber Bragg grating (FBG) and an optical filter has been devised for the magnetostriction measurements under ultrahigh magnetic fields. The longitudinal magnetostriction of LaCoO 3 has been measured at room temperature, 115, 7 and 4.2 K up to the maximum magnetic field of 150 T. The field-induced lattice elongations are observed, which are attributed to the spin-state crossover from the low-spin ground state to excited spin-states.

40 MHz high-frequency ultrafast ultrasound imaging.

PubMed

Huang, Chih-Chung; Chen, Pei-Yu; Peng, Po-Hsun; Lee, Po-Yang

2017-06-01

Ultrafast high-frame-rate ultrasound imaging based on coherent-plane-wave compounding has been developed for many biomedical applications. Most coherent-plane-wave compounding systems typically operate at 3-15 MHz, and the image resolution for this frequency range is not sufficient for visualizing microstructure tissues. Therefore, the purpose of this study was to implement a high-frequency ultrafast ultrasound imaging operating at 40 MHz. The plane-wave compounding imaging and conventional multifocus B-mode imaging were performed using the Field II toolbox of MATLAB in simulation study. In experiments, plane-wave compounding images were obtained from a 256 channel ultrasound research platform with a 40 MHz array transducer. All images were produced by point-spread functions and cyst phantoms. The in vivo experiment was performed from zebrafish. Since high-frequency ultrasound exhibits a lower penetration, chirp excitation was applied to increase the imaging depth in simulation. The simulation results showed that a lateral resolution of up to 66.93 μm and a contrast of up to 56.41 dB were achieved when using 75-angles plane waves in compounding imaging. The experimental results showed that a lateral resolution of up to 74.83 μm and a contrast of up to 44.62 dB were achieved when using 75-angles plane waves in compounding imaging. The dead zone and compounding noise are about 1.2 mm and 2.0 mm in depth for experimental compounding imaging, respectively. The structure of zebrafish heart was observed clearly using plane-wave compounding imaging. The use of fewer than 23 angles for compounding allowed a frame rate higher than 1000 frames per second. However, the compounding imaging exhibits a similar lateral resolution of about 72 μm as the angle of plane wave is higher than 10 angles. This study shows the highest operational frequency for ultrafast high-frame-rate ultrasound imaging. © 2017 American Association of Physicists in Medicine.

47 CFR 15.33 - Frequency range of radiated measurements.

Code of Federal Regulations, 2014 CFR

2014-10-01

... kHz, up to at least the frequency shown in this paragraph: (1) If the intentional radiator operates... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown in...

47 CFR 15.33 - Frequency range of radiated measurements.

Code of Federal Regulations, 2011 CFR

2011-10-01

... kHz, up to at least the frequency shown in this paragraph: (1) If the intentional radiator operates... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown in...

47 CFR 15.33 - Frequency range of radiated measurements.

Code of Federal Regulations, 2012 CFR

2012-10-01

... kHz, up to at least the frequency shown in this paragraph: (1) If the intentional radiator operates... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown in...

47 CFR 15.33 - Frequency range of radiated measurements.

Code of Federal Regulations, 2013 CFR

2013-10-01

... kHz, up to at least the frequency shown in this paragraph: (1) If the intentional radiator operates... level of radiated emissions within the frequency range 9 kHz to 30 MHz, such as a CB receiver or a... used in the device, without going below 9 kHz (25 MHz for CB receivers), up to the frequency shown in...

20 MHz/40 MHz dual element transducers for high frequency harmonic imaging.

PubMed

Kim, Hyung Ham; Cannata, Jonathan M; Liu, Ruibin; Chang, Jin Ho; Silverman, Ronald H; Shung, K Kirk

2008-12-01

Concentric annular type dual element transducers for second harmonic imaging at 20 MHz / 40 MHz were designed and fabricated to improve spatial resolution and depth of penetration for ophthalmic imaging applications. The outer ring element was designed to transmit the 20 MHz signal and the inner circular element was designed to receive the 40 MHz second harmonic signal. Lithium niobate (LiNbO(3)), with its low dielectric constant, was used as the piezoelectric material to achieve good electrical impedance matching. Double matching layers and conductive backing were used and optimized by KLM modeling to achieve high sensitivity and wide bandwidth for harmonic imaging and superior time-domain characteristics. Prototype transducers were fabricated and evaluated quantitatively and clinically. The average measured center frequency for the transmit ring element was 21 MHz and the one-way --3 dB bandwidth was greater than 50%. The 40 MHz receive element functioned at 31 MHz center frequency with acceptable bandwidth to receive attenuated and frequency downshifted harmonic signal. The lateral beam profile for the 20 MHz ring elements at the focus matched the Field II simulated results well, and the effect of outer ring diameter was also examined. Images of a posterior segment of an excised pig eye and a choroidal nevus of human eye were obtained both for single element and dual element transducers and compared to demonstrate the advantages of dual element harmonic imaging.

20 MHz/40 MHz Dual Element Transducers for High Frequency Harmonic Imaging

PubMed Central

Kim, Hyung Ham; Cannata, Jonathan M.; Liu, Ruibin; Chang, Jin Ho; Silverman, Ronald H.; Shung, K. Kirk

2009-01-01

Concentric annular type dual element transducers for second harmonic imaging at 20 MHz / 40 MHz were designed and fabricated to improve spatial resolution and depth of penetration for ophthalmic imaging applications. The outer ring element was designed to transmit the 20 MHz signal and the inner circular element was designed to receive the 40 MHz second harmonic signal. Lithium niobate (LiNbO3), with its low dielectric constant, was used as the piezoelectric material to achieve good electrical impedance matching. Double matching layers and conductive backing were used and optimized by KLM modeling to achieve high sensitivity and wide bandwidth for harmonic imaging and superior time-domain characteristics. Prototype transducers were fabricated and evaluated quantitatively and clinically. The average measured center frequency for the transmit ring element was 21 MHz and the one-way –3 dB bandwidth was greater than 50%. The 40 MHz receive element functioned at 31 MHz center frequency with acceptable bandwidth to receive attenuated and frequency downshifted harmonic signal. The lateral beam profile for the 20 MHz ring elements at the focus matched the Field II simulated results well, and the effect of outer ring diameter was also examined. Images of a posterior segment of an excised pig eye and a choroidal nevus of human eye were obtained both for single element and dual element transducers and compared to demonstrate the advantages of dual element harmonic imaging. PMID:19126492

Effect of 900 MHz radio frequency radiation on beta amyloid protein, protein carbonyl, and malondialdehyde in the brain.

PubMed

Dasdag, Suleyman; Akdag, Mehmet Zulkuf; Kizil, Goksel; Kizil, Murat; Cakir, Dilek Ulker; Yokus, Beran

2012-03-01

Recently, many studies have been carried out in relation to 900 MHz radiofrequency radiation (RF) emitted from a mobile phone on the brain. However, there is little data concerning possible mechanisms between long-term exposure of RF radiation and biomolecules in brain. Therefore, we aimed to investigate long-term effects of 900 MHz radiofrequency radiation on beta amyloid protein, protein carbonyl, and malondialdehyde in the rat brain. The study was carried out on 17 Wistar Albino adult male rats. The rat heads in a carousel were exposed to 900 MHz radiofrequency radiation emitted from a generator, simulating mobile phones. For the study group (n: 10), rats were exposed to the radiation 2 h per day (7 days a week) for 10 months. For the sham group (n: 7), rats were placed into the carousel and the same procedure was applied except that the generator was turned off. In this study, rats were euthanized after 10 months of exposure and their brains were removed. Beta amyloid protein, protein carbonyl, and malondialdehyde levels were found to be higher in the brain of rats exposed to 900 MHz radiofrequency radiation. However, only the increase of protein carbonyl in the brain of rats exposed to 900 MHz radiofrequency radiation was found to be statistically significant (p<0.001). In conclusion, 900 MHz radiation emitted from mobile/cellular phones can be an agent to alter some biomolecules such as protein. However, further studies are necessary.

47 CFR 15.245 - Operation within the bands 902-928 MHz, 2435-2465 MHz, 5785-5815 MHz, 10500-10550 MHz, and 24075...

Code of Federal Regulations, 2010 CFR

2010-10-01

... limited to intentional radiators used as field disturbance sensors, excluding perimeter protection systems. (b) The field strength of emissions from intentional radiators operated within these frequency bands shall comply with the following: Fundamental frequency (MHz) Field strength of fundamental (millivolts...

Transmission of 100-MHz-range ultrasound through a fused quartz fiber.

PubMed

Irie, Takasuke; Tagawa, Norio; Tanabe, Masayuki; Moriya, Tadashi; Yoshizawa, Masasumi; Iijima, Takashi; Itoh, Kouichi; Yokoyama, Taku; Kumagai, Hideki; Taniguchi, Nobuyuki

2011-07-01

This paper describes an investigation into direct observation of microscopic images of tissue using a thin acoustic wave guide. First, the characteristics of the ultrasonic wave propagated in a fused quartz fiber were measured using the reflection method in order to study the insertion loss and the frequency shift of the ultrasonic wave transmitted from the transducer. Next, a receiving transducer was placed close to the end of the fiber, and the characteristics of the ultrasonic waves propagated through the acoustic coupling medium were measured using the penetration method in order to study the insertion loss and the frequency-dependent attenuation of the penetrated waves. Finally, a C-mode image was obtained by optimizing the measuring conditions using the results of the above measurements and scanning the ultrasonic beams on a target (coin) in water. A reflected wave with a peak frequency of approximately 220 MHz was obtained from the end of the fiber. The transmitted ultrasonic waves propagated through the acoustic coupling medium were detected with a frequency range of approximately 125-170 MHz, and the maximum detectable distance of the waves was approximately 1.2 mm within the 100-MHz frequency range. Finally, a high-frequency C-mode image of a coin in water was obtained using a tapered fused quartz fiber. The results suggest that it is necessary to improve the signal-to-noise ratio and reduce the insertion loss in the experimental system in order to make it possible to obtain microscopic images of tissue.

[Effect of Low-Intensity 900 MHz Frequency Electromagnetic Radiation on Rat Brain Enzyme Activities Linked to Energy Metabolism].

PubMed

Petrosyan, M S; Nersesova, L S; Gazaryants, M G; Meliksetyan, G O; Malakyan, M G; Bajinyan, S A; Akopian, J I

2015-01-01

The research deals with the effect of low-intensity 900 MHz frequency electromagnetic radiation (EMR), power density 25 μW/cm2, on the following rat brain and blood serum enzyme activities: creatine kinase (CK), playing a central role in the process of storing and distributing the cell energy, as well as alanine aminotransferase (ALT) and aspartate aminotransferase (AST) that play a key role in providing the conjunction of carbohydrate and amino acid metabolism. The comparative analysis of the changes in the enzyme activity studied at different times following the two-hour single, as well as fractional, radiation equivalent of the total time showed that the most radiosensitive enzyme is the brain creatine kinase, which may then be recommended as a marker of the radio frequency radiation impact. According to the analysis of the changing dynamics of the CK, ALT and AST activity level, with time these changes acquire the adaptive character and are directed to compensate the damaged cell energy metabolism.

Lightning electromagnetic radiation field spectra in the interval from 0. 2 to 20 MHz

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

Willett, J.C.; Bailey, J.C.; Leteinturier, C.

1990-11-20

Average energy spectral densities are presented for the fast transitions in most of the components that produce large radiation field impulses from cloud-to-ground lightning; first and subsequent return strokes; stepped, dart-stepped, and 'chaotic' leaders; and 'characteristic' cloud pulses. A disagreement in the previous literature about the spectral energy radiated by return strokes at high frequencies is noted and explained. The authors show that the spectral amplitudes are not seriously distorted by propagation over less than 35 km of seawater, although as much as 45 km of such propagation does appear to produce significant attenuation above about 10 MHz. First andmore » subsequent return strokes produce identical spectra between 0.2 and 20 MHz. The spectra of stepped and dart-stepped leader steps are nearly identical and are very similar to that of characteristic pulses. The spectra of leader steps also match return stroke spectra above 2-3 MHz after the former are increased by about 7 dB. The shapes of individual spectra do not depend on their amplitude, so the shapes of the average spectra are probably not distorted by the trigger thresholds used in the data acquisition. Return strokes are the strongest sources of radiation from cloud-to-ground lightning in the 0.2- to 20-MHz frequency range, although certain intracloud processes are stronger radiators above 8 MHz.« less

Imaging Jupiter's radiation belts down to 127 MHz with LOFAR

NASA Astrophysics Data System (ADS)

Girard, J. N.; Zarka, P.; Tasse, C.; Hess, S.; de Pater, I.; Santos-Costa, D.; Nenon, Q.; Sicard, A.; Bourdarie, S.; Anderson, J.; Asgekar, A.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Bonafede, A.; Breitling, F.; Breton, R. P.; Broderick, J. W.; Brouw, W. N.; Brüggen, M.; Ciardi, B.; Corbel, S.; Corstanje, A.; de Gasperin, F.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Falcke, H.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Iacobelli, M.; Juette, E.; Kondratiev, V. I.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Loose, M.; Maat, P.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Moldon, J.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H.; Rowlinson, A.; Schwarz, D.; Smirnov, O.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijers, R. A. M. J.; Wucknitz, O.

2016-03-01

Context. With the limited amount of in situ particle data available for the innermost region of Jupiter's magnetosphere, Earth-based observations of the giant planets synchrotron emission remain the sole method today of scrutinizing the distribution and dynamical behavior of the ultra energetic electrons magnetically trapped around the planet. Radio observations ultimately provide key information about the origin and control parameters of the harsh radiation environment. Aims: We perform the first resolved and low-frequency imaging of the synchrotron emission with LOFAR. At a frequency as low as 127 MHz, the radiation from electrons with energies of ~1-30 MeV are expected, for the first time, to be measured and mapped over a broad region of Jupiter's inner magnetosphere. Methods: Measurements consist of interferometric visibilities taken during a single 10-hour rotation of the Jovian system. These visibilities were processed in a custom pipeline developed for planetary observations, combining flagging, calibration, wide-field imaging, direction-dependent calibration, and specific visibility correction for planetary targets. We produced spectral image cubes of Jupiter's radiation belts at the various angular, temporal, and spectral resolutions from which flux densities were measured. Results: The first resolved images of Jupiter's radiation belts at 127-172 MHz are obtained with a noise level ~20-25 mJy/beam, along with total integrated flux densities. They are compared with previous observations at higher frequencies. A greater extent of the synchrotron emission source (≥4 RJ) is measured in the LOFAR range, which is the signature - as at higher frequencies - of the superposition of a "pancake" and an isotropic electron distribution. Asymmetry of east-west emission peaks is measured, as well as the longitudinal dependence of the radial distance of the belts, and the presence of a hot spot at λIII = 230° ± 25°. Spectral flux density measurements are on the low

Local exposure of 849 MHz and 1763 MHz radiofrequency radiation to mouse heads does not induce cell death or cell proliferation in brain

PubMed Central

Kim, Tae-Hyoung; Huang, Tai-Qin; Jang, Ja-June; Kim, Man Ho; Kim, Hyun-Jeong; Lee, Jae-Seon; Pack, Jeong Ki; Seo, Jeong-Sun

2008-01-01

Even though there is no direct evidence to prove the cellular and molecular changes induced by radiofrequency (RF) radiation itself, we cannot completely exclude the possibility of any biological effect of mobile phone frequency radiation. We established a carousel-type exposure chamber for 849 MHz or 1763 MHz of mobile phone RF radiation to expose RF to the heads of C57BL mice. In this chamber, animals were irradiated intermittently at 7.8 W/kg for a maximum of 12 months. During this period, the body weights of 3 groups-sham, 849 MHz RF, and 1763 MHz RF-did not show any differences between groups. The brain tissues were obtained from 3 groups at 6 months and 12 months to examine the differences in histology and cell proliferation between control and RF exposure groups, but we could not find any change upon RF radiation. Likewise, we could not find changes in the expression and distribution of NeuN and GFAP in hippocampus and cerebellum, or in cell death by TUNEL assay in RF exposure groups. From these data, we conclude that the chronic exposure to 849 MHz and 1763 MHz RF radiation at a 7.8 W/kg specific absorption rate (SAR) could not induce cellular alterations such as proliferation, death, and reactive gliosis. PMID:18587267

Cytogenetic studies in human blood lymphocytes exposed in vitro to radiofrequency radiation at a cellular telephone frequency (835.62 MHz, FDMA).

PubMed

Vijayalaxmi; Leal, B Z; Meltz, M L; Pickard, W F; Bisht, K S; Roti Roti JL; Straube, W L; Moros, E G

2001-01-01

Freshly collected peripheral blood samples from four healthy human volunteers were diluted with RPMI 1640 tissue culture medium and exposed in sterile T-75 tissue culture flasks in vitro for 24 h to 835.62 MHz radiofrequency (RF) radiation, a frequency employed for customer-to-base station transmission of cellular telephone communications. An analog signal was used, and the access technology was frequency division multiple access (FDMA, continuous wave). A nominal net forward power of 68 W was used, and the nominal power density at the center of the exposure flask was 860 W/m(2). The mean specific absorption rate in the exposure flask was 4.4 or 5.0 W/kg. Aliquots of diluted blood that were sham-exposed or exposed in vitro to an acute dose of 1.50 Gy of gamma radiation were used as negative or positive controls. Immediately after the exposures, the lymphocytes were stimulated with a mitogen, phytohemagglutinin, and cultured for 48 or 72 h to determine the extent of genetic damage, as assessed from the frequencies of chromosomal aberrations and micronuclei. The extent of alteration in the kinetics of cell proliferation was determined from the mitotic indices in 48-h cultures and from the incidence of binucleate cells in 72-h cultures. The data indicated no significant differences between RF-radiation- and sham-exposed lymphocytes with respect to mitotic indices, incidence of exchange aberrations, excess fragments, binucleate cells, and micronuclei. In contrast, the response of the lymphocytes exposed to gamma radiation was significantly different from both RF-radiation- and sham-exposed cells for all of these indices. Thus, under the experimental conditions tested, there is no evidence for the induction of chromosomal aberrations and micronuclei in human blood lymphocytes exposed in vitro for 24 h to 835.62 MHz RF radiation at SARs of 4.4 or 5.0 W/kg.

[Effect of low-intensity 900 MHz frequency electromagnetic radiation on rat liver and blood serum enzyme activities].

PubMed

Nersesova, L S; Petrosian, M S; Gazariants, M G; Mkrtchian, Z S; Meliksetian, G O; Pogosian, L G; Akopian, Zh I

2014-01-01

The comparative analysis of the rat liver and blood serum creatine kinase, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and purine nucleoside phosphorylase post-radiation activity levels after a total two-hour long single and fractional exposure of the animals to low-intensity 900 MHz frequency electromagnetic field showed that the most sensitive enzymes to the both schedules of radiation are the liver creatine kinase, as well as the blood serum creatine kinase and alkaline phosphatase. According to the comparative analysis of the dynamics of changes in the activity level of the liver and blood serum creatine kinase, alanine aminotransferase, aspartate aminotransferase and purine nucleoside phosphorylase, both single and fractional radiation schedules do not affect the permeability of a hepatocyte cell membrane, but rather cause changes in their energetic metabolism. The correlation analysis of the post-radiation activity level changes of the investigated enzymes did not reveal a clear relationship between them. The dynamics of post-radiation changes in the activity of investigated enzyme levels following a single and short-term fractional schedules of radiation did not differ essentially.

Measurement of the 100 MHz EMF radiation in vivo effects on zebrafish D. rerio embryonic development: A multidisciplinary study.

PubMed

Piccinetti, Chiara Carla; De Leo, Alfredo; Cosoli, Gloria; Scalise, Lorenzo; Randazzo, Basilio; Cerri, Graziano; Olivotto, Ike

2018-06-15

The augmented exposure of both environment and human being to electromagnetic waves and the concomitant lack of an unequivocal knowledge about biological consequences of these radiations, raised public interest on electromagnetic pollution. In this context, the present study aims to evaluate the biological effects on zebrafish (ZF) embryos of 100 MHz radiofrequency electromagnetic field (RF-EMF) exposure through a multidisciplinary protocol. Because of the shared synteny between human and ZF genomes that validated its use in biomedical research, toxicology and developmental biology studies, ZF was here selected as experimental model and a measurement protocol and biological analyses have been set up to clearly discriminate between RF-EMF biological and thermal effects. The results showed that a 100 MHz EMF was able to affect ZF embryonic development, from 24 to 72 h post fertilization (hpf) in all the analyzed pathways. Particularly, at the 48 hpf stage, a reduced growth, an increased transcription of oxidative stress genes, the onset of apoptotic/autophagic processes and a modification in cholesterol metabolism were detected. ZF embryos faced stress induced by EMF radiation by triggering detoxification mechanisms and at 72 hpf they partially recovered from stress reaching the hatching time in a comparable way respect to the control group. Data here obtained showed unequivocally the in vivo effects of RF-EMF on an animal model, excluding thermal outcomes and thus represents the starting point for more comprehensive studies on dose response effects of electromagnetic fields radiations consequences. Copyright © 2018 Elsevier Inc. All rights reserved.

Imaging Buried Culverts Using Ground Penetrating Radar: Comparing 100 MHZ Through 1 GHZ Antennae

NASA Astrophysics Data System (ADS)

Abdul Aziz, A.; Stewart, R. R.; Green, S. L.

2013-12-01

*Aziz, A A aabdulaziz@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA Stewart, R R rrstewart@uh.edu Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA *Green, S L slgreen@yahoo.com Allied Geophysical Lab, Department of Earth and Atmospheric Sciences, University of Houston, TX, USA A 3D ground penetrating radar (GPR) survey, using three different frequency antennae, was undertaken to image buried steel culverts at the University of Houston's La Marque Geophysical Observatory 30 miles south of Houston, Texas. The four culverts, under study, support a road crossing one of the area's bayous. A 32 m by 4.5 m survey grid was designed on the road above the culverts and data were collected with 100 MHz, 250 MHz, and 1 GHz antennae. We used an orthogonal acquisition geometry for the three surveys. Inline sampling was from 1.0 cm to 10 cm (from 1 GHz to 100 MHz antenna) with inline and crossline spacings ranging from 0.2 m to 0.5 m. We used an initial velocity of 0.1 m/ns (from previous CMP work at the site) for the display purposes. The main objective of the study was to analyze the effect of different frequency antennae on the resultant GPR images. We are also interested in the accuracy and resolution of the various images, in addition to developing an optimal processing flow.The data were initially processed with standard steps that included gain enhancement, dewow and temporal-filtering, background suppression, and 2D migration. Various radar velocities were used in the 2D migration and ultimately 0.12 m/ns was used. The data are complicated by multipathing from the surface and between culverts (from modeling). Some of this is ameliorated via deconvolution. The top of each of the four culverts was evident in the GPR images acquired with the 250 MHz and 100 MHz antennas. For 1 GHz, the top of the culvert was not clear due to the signal's attenuation. The 250 MHz

Interdigital pair bonding for high frequency (20-50 MHz) ultrasonic composite transducers.

PubMed

Liu, R; Harasiewicz, K A; Foster, F S

2001-01-01

Interdigital pair bonding is a novel methodology that enables the fabrication of high frequency piezoelectric composites with high volume fractions of the ceramic phase. This enhancement in ceramic volume fraction significantly reduces the dimensional scale of the epoxy phase and increases the related effective physical parameters of the composite, such as dielectric constant and the longitudinal sound velocity, which are major concerns in the development of high frequency piezoelectric composites. In this paper, a method called interdigital pair bonding (IPB) is used to prepare 1-3 piezoelectric composite with a pitch of 40 microns, a kerf of 4 microns, and a ceramic volume fraction of 81%. The composites prepared in this fashion exhibited a very pure thickness-mode resonance up to a frequency of 50 MHz. Unlike the 2-2 piezoelectric composites with the same ceramic and epoxy scales developed earlier, the anticipated lateral modes between 50 to 100 MHz were not observed in the current 1-3 composites. The mechanisms for the elimination of the lateral modes at high frequency are discussed. The effective electromechanical coupling coefficient of the composite was 0.72 at a frequency of 50 MHz. The composites showed a high longitudinal sound velocity of 4300 m/s and a high clamped dielectric constant of 1111 epsilon 0, which will benefit the development of high frequency ultrasonic transducers and especially high frequency transducer arrays for medical imaging.

Frequency Arrangement For 700 MHz Band

NASA Astrophysics Data System (ADS)

Ancans, G.; Bobrovs, V.; Ivanovs, G.

2015-02-01

The 694-790 MHz (700 MHz) band was allocated by the 2012 World Radiocommunication Conference (WRC-12) in ITU Region 1 (Europe included), to the mobile service on a co-primary basis with other services to which this band was allocated on the primary basis and identified for the International Mobile Telecommunications (IMT). At the same time, the countries of Region 1 will be able also to continue using these frequencies for their broadcasting services if necessary. This allocation will be effective immediately after 2015 World Radiocommunication Conference (WRC-15). In order to make the best possible use of this frequency band for mobile service, a worldwide harmonized frequency arrangement is to be prepared to allow for large economies of scale and international roaming as well as utilizing the available spectrum in the best possible way, minimizing possible interference between services, facilitating deployment and cross-border coordination. The authors analyze different possible frequency arrangements and conclude on the frequency arrangement most suitable for Europe.

Influence of 1800 MHz GSM-like electromagnetic radiation exposure on fracture healing.

PubMed

Aslan, Ahmet; Kırdemır, Vecihi; Kocak, Ahmet; Atay, Tolga; Baydar, Metin Lütfi; Özerdemoglu, Remzi Arif; Aydogan, Nevres Hürriyet

2014-02-01

In this study, we aimed to investigate whether 1800 MHz frequency electromagnetic radiation (EMR) has an effect on bone healing. A total of 30 Wistar albino rats were divided into two equal groups. Fractures were created in the right tibias of all rats; next, intramedullary fixations with K-wire were performed. A control group (Group I) was kept under the same experimental conditions except without EMR exposure. Rats in Group II were exposed to an 1800 MHz frequency EMR for 30 min a day for 5 days a week. Next, radiological, mechanical, and histological examinations were performed to evaluate tibial fracture healing. Radiological, histological and mechanical scores were not significantly different between groups (respectively, p = 0.114, p = 0.184 and p = 0.083), and all of these scores were lower than those of the controls. EMR at 1800 MHz frequency emitted from cellular phones has no effect on bone fracture healing. Copyright © 2014 IMSS. Published by Elsevier Inc. All rights reserved.

Assessment of the Nucleus-to-Cytoplasmic Ratio in MCF-7 Cells Using Ultra-high Frequency Ultrasound and Photoacoustics

NASA Astrophysics Data System (ADS)

Moore, M. J.; Strohm, E. M.; Kolios, M. C.

2016-12-01

The nucleus-to-cytoplasmic (N:C) ratio of a cell is often used when assessing histology for the presence of malignant disease. In this proof of concept study, we present a new, non-optical method for determination of the N:C ratio using ultra-high Frequency ultrasound (US) and photoacoustics (PA). When using transducers in the 100 MHz-500 MHz range, backscattered US pulses and emitted PA waves are encoded with information pertaining to the dimension and morphology of micron-sized objects. If biological cells are interrogated, the diameter of the scattering or absorbing structure can be assessed by fitting the power spectra of the measured US or PA signals to theoretical models for US backscatter and PA emission from a fluid sphere. In this study, the cell and nucleus diameters of 9 MCF-7 breast cancer cells were determined using a new simplified model that calculates the theoretical values of the location of the power spectra minima for both US and PA signals. These diameters were then used to calculate the N:C ratio of the measured cells. The average cell diameter determined by US pulses from a transducer with a central frequency of 375 MHz was found to be 15.5 μ m± 1.8 μ m. The PA waves emitted by the cell nuclei were used to determine an average nuclear diameter of 12.0 μ m± 1.3 μ m. The N:C ratio for these cells was calculated to be 1.9± 1.0, which agrees well with previously reported N:C values for this cell type.

[The combined action of drinking mineral water and low-intensity electromagnetic radiation under the immobilization stress conditions (an experimental study)].

PubMed

Korolev, Yu N; Bobrovnitsky, I P; Geniatulina, M S; Mikhailik, L V; Nikulina, L A; Bobkova, A S; Yakovlev, M Yu

2015-01-01

The present study carried out on white male rats in experiments with the use of biochemical, radioimmunological, and electron- microscopic methods. It was shown that the combined treatment with potable mineral water (MV) and low-intensity electromagnetic radiation (LIEMR) of ultrahigh frequency (power density less than 1 pW/cm2, the frequency about 1000 MHz) facilitated the activation of metabolic and intracellular regenerative processes in the liver and testes. One of the advantages of the combined application of MV and LIEMR over the single-factor treatment manifested itself as the weakening of stress reactions, the increase in the frequency of the plastic processes, and the more harmonious development of different forms of intracellular regeneration. The results of the study provide a deeper insight ino the mechanisms underlying the combined actions of drinking mineral water and low-intensity electromagnetic radiation; also, they justify the application of these factors for the protection of the reproductive system and the entire body from stress-induced disorders.

Ultrahigh Frequency Nanomechanical Piezoresistive Amplifiers for Direct Channel-Selective Receiver Front-Ends.

PubMed

Ramezany, Alireza; Pourkamali, Siavash

2018-04-11

Channel-selective filtering and amplification in ultrahigh frequency (UHF) receiver front-ends are crucial for realization of cognitive radio systems and the future of wireless communication. In the past decade, there have been significant advances in the performance of microscale electromechanical resonant devices. However, such devices have not yet been able to meet the requirements for direct channel selection at RF. They also occupy a relatively large area on the chip making implementation of large arrays to cover several frequency bands challenging. On the other hand, electromechanical piezoresistive resonant devices are active devices that have recently shown the possibility of simultaneous signal amplification and channel-select filtering at lower frequencies. It has been theoretically predicted that if scaled down into the nanoscale, they can operate in the UHF range with a very low power consumption. Here, for the first time nanomechanical piezoresistive amplifiers with active element dimensions as small as 50 nm × 200 nm are demonstrated. With a device area of less than 1.5 μm 2 a piezoresistive amplifier operating at 730 MHz shows effective quality factor ( Q) of 89,000 for a 50Ω load and gains as high as 10 dB and Q of 330,000 for a 250Ω load while consuming 189 μW of power. On the basis of the measurement results, it is shown that for piezoresistor dimensions of 30 nm × 100 nm it is possible to get a similar performance at 2.4 GHz with device footprint of less than 0.2 μm 2 .

Modelling and simulation of high-frequency (100 MHz) ultrasonic linear arrays based on single crystal LiNbO3.

PubMed

Zhang, J Y; Xu, W J; Carlier, J; Ji, X M; Nongaillard, B; Queste, S; Huang, Y P

2012-01-01

High-frequency ultrasonic transducer arrays are essential for high resolution imaging in clinical analysis and Non-Destructive Evaluation (NDE). However, the fabrication of conventional backing-layer structure, which requires a pitch (distance between the centers of two adjacent elements) of half wavelength in medium, is really a great challenge. Here we present an alternative buffer-layer structure with a silicon lens for volumetric imaging. The requirement for the size of the pitch is less critical for this structure, making it possible to fabricate high-frequency (100MHz) ultrasonic linear array transducers. Using silicon substrate also makes it possible to integrate the arrays with IC (Integrated Circuit). To compare with the conventional backing-layer structure, a finite element tool, COMSOL, is employed to investigate the performances of acoustic beam focusing, the influence of pitch size for the buffer-layer configuration, and to calculate the electrical properties of the arrays, including crosstalk effect and electrical impedance. For a 100MHz 10-element array of buffer-layer structure, the ultrasound beam in azimuth plane in water could be electronically focused to obtain a spatial resolution (a half-amplitude width) of 86μm at the focal depth. When decreasing from half wavelength in silicon (42μm) to half wavelength in water (7.5μm), the pitch sizes weakly affect the focal resolution. The lateral spatial resolution is increased by 4.65% when the pitch size decreases from 42μm to 7.5μm. The crosstalk between adjacent elements at the central frequency is, respectively, -95dB, -39.4dB, and -60.5dB for the 10-element buffer, 49-element buffer and 49-element backing arrays. Additionally, the electrical impedance magnitudes for each structure are, respectively, 4kΩ, 26.4kΩ, and 24.2kΩ, which is consistent with calculation results using Krimholtz, Leedom, and Matthaei (KLM) model. These results show that the buffer-layer configuration is a promising

TEM Cell Testing of Cable Noise Reduction Techniques from 2 MHz to 200 MHz -- Part 2

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Evans, William C.; Reed, Joshua L.; Shimp, Samuel K., III; Fitzpatrick, Fred D.

2008-01-01

This paper presents empirical results of cable noise reduction techniques as demonstrated in a TEM cell operating with radiated fields from 2 - 200 MHz. It is the second part of a two-paper series. The first paper discussed cable types and shield connections. In this second paper, the effects of load and source resistances and chassis connections are examined. For each topic, well established theories are compared to data from a real-world physical system. Finally, recommendations for minimizing cable susceptibility (and thus cable emissions) are presented. There are numerous papers and textbooks that present theoretical analyses of cable noise reduction techniques. However, empirical data is often targeted to low frequencies (e.g. <50 KHz) or high frequencies (>100 MHz). Additionally, a comprehensive study showing the relative effects of various noise reduction techniques is needed. These include the use of dedicated return wires, twisted wiring, cable shielding, shield connections, changing load or source impedances, and implementing load- or source-to-chassis isolation. We have created an experimental setup that emulates a real-world electrical system, while still allowing us to independently vary a host of parameters. The goal of the experiment was to determine the relative effectiveness of various noise reduction techniques when the cable is in the presence of radiated emissions from 2 MHz to 200 MHz.

Characterization of Acoustic Streaming Beyond 100 MHz

NASA Astrophysics Data System (ADS)

Eisener, J.; Lippert, A.; Nowak, T.; Cairós, C.; Reuter, F.; Mettin, R.

The aim of this study is to investigate acoustic streaming in water at very high ultrasonic frequencies, namely beyond 100 MHz. At such high frequencies, the dissipation length of acoustic waves shrinks considerably, and the acoustic streaming transforms from the well-known Eckart type into a Stuart-Lighthill type: While Eckart streaming is driven by a small momentum transfer along the path of a weakly damped travelling sound wave, Stuart-Lighthill streaming is generated by rather local and strong momentum transfer of a highly damped and therefore rapidly decaying wave. Then the inertia of the induced flow cannot be neglected anymore, and a potentially turbulent jet flow emerges. Here we report on streaming velocity measurements for the case where the sound is completely absorbed within a region much smaller than the generated jet. In contrast to previous work in this frequency range, where mainly surface acoustic wave transducers have been employed, we use piston-type transducers that emit vertically to the transducer surface. The acoustic streaming effects are characterized by ink front tracking and particle tracking velocimetry, and by numerical studies. The results show narrow high-speed jet flows that extend much farther into the liquid than the acoustic field. Velocities of several m/s are observed.

Effects of radio frequency identification-related radiation on in vitro biologics.

PubMed

Uysal, Ismail; Hohberger, Clive; Rasmussen, R Scott; Ulrich, David A; Emond, Jean-Pierre; Gutierrez, Alfonso

2012-01-01

The recent developments on the use of e-pedigree to identify the chain of custody of drugs suggests the use of advanced track and trace technologies such as two-dimensional barcodes and radio frequency identification (RFID) tags. RFID technology is used mainly for valuable commodities such as pharmaceutical products while incorporating additional functionalities like monitoring environmental variables to ensure product safety and quality. In its guidance for the use of RFID technologies for drugs (Compliance Policy Guide Section 400.210), the Food and Drug Administration outlined multiple parameters that would apply to any study or application using RFID. However, drugs approved under a Biologics License Application or protein drugs covered by a New Drug Application were excluded mainly due to concerns about the effects of radio frequency radiation (thermal and/or non-thermal) on biologics. Even though the thermal effects of radio frequency on biologics are relatively well understood, there are few studies in the literature about the non-thermal effects of radio frequency with regards to the protein structure integrity. In this paper, we analyze the non-thermal effects of radio frequency radiation by exposing a wide variety of biologics including biopharmaceuticals with vaccines, hormones, and immunoglobulins, as well as cellular blood products such as red blood cells and whole blood-derived platelets as well as fresh frozen plasma. In order to represent the majority of the frequency spectrum used in RFID applications, five different frequencies (13.56 MHz, 433 MHz, 868 MHz, 915 MHz, and 2.4 GHz) are used to account for the most commonly used international frequency bands for RFID. With the help of specialized radio frequency signal-generating hardware, magnetic and electromagnetic fields are created around the exposed products with power levels greater than Federal Communications Commission-regulated limits. The in vitro test results on more than 100

Impact on storage quality of red blood cells and platelets by ultrahigh-frequency radiofrequency identification tags.

PubMed

Wang, Quan-Li; Wang, Xiao-Wei; Zhuo, Hai-Long; Shao, Chun-Yan; Wang, Jie; Wang, Hai-Ping

2013-04-01

Compared to ISBT128 code labels, radiofrequency identification (RFID) tags have incomparable advantages and gradually applied in blood management system. However, there is no global standard for the uses of RFID frequency. Even though ISBT recommended high-frequency RFID with 13.56MHz, 820- to 960-MHz ultrahigh frequency (UHF) RFID technology in many ways has even more advantages. For this reason, we studied the effect of UHF RFID tags with 820- to 960-MHz exposure on storage quality of red blood cells (RBCs) and platelets (PLTs). Thirty units of collected and prepared suspended RBCs (sRBCs) and PLTs were divided into two bags, one each for the test and control groups. The sRBCs were stored in 4±2°C refrigerator and the PLTs in a 22±2°C rocking box. The test groups were exposed to RF reader continuously during storage. Sampling at different time points and biologic changes were tested. As the extension of storage and the pH and chlorine levels in the supernatant of sRBCs were reduced, free hemoglobin, potassium, and sodium increased, but were not significant between test and control groups (p>0.05). During the storage period, the pH levels, PLT count, and PLT aggregation rate were decreased in both test and control groups, but were not significant (p>0.05). When exposed to 820- to 960-MHz RF, the biologic and biochemical indexes are not found to be exacerbated during 35 days of storage for sRBCs and 5 days for PLTs, respectively. © 2012 American Association of Blood Banks.

Aircraft measurement of radio frequency noise at 121.5 MHz, 243 MHz and 406 MHz

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Hill, J. S.

1977-01-01

An airborne survey measurement of terrestrial radio-frequency noise over U.S. metropolitan areas was carried out at 121.5, 243 and 406 MHz with horizontal-polarization monopole antennas. Flights were at 25,000 feet altitude. Radio-noise measurements, expressed in equivalent antenna-noise temperature, indicate a steady-background noise temperature of 572,000 K, at 121.5 MHz, during daylight over New York City. This data is helpful in compiling radio-noise temperature maps; in turn useful for designing satellite-aided, emergency-distress search and rescue communication systems.

Study of cavity type antenna structure of large-area 915 MHz ultra-high frequency wave plasma device based on three-dimensional finite difference time-domain analysis

NASA Astrophysics Data System (ADS)

Chang, Xijiang; Kunii, Kazuki; Liang, Rongqing; Nagatsu, Masaaki

2013-11-01

A large-area planar plasma source with a resonant cavity type launcher driven by a 915 MHz ultra-high frequency wave was developed. Theoretical analysis with the three-dimensional finite difference time-domain simulation was carried out to determine the optimized launcher structure by analyzing the resonant transverse magnetic mode in the resonant cavity. Numerical result expects that the resonant electric field distribution inside the cavity dominantly consists of the TM410 mode. The resonant cavity type launcher having 8 holes in an octagonal geometry was designed to fit the resonant transverse magnetic mode. Adjusting 8 hole positions of the launcher to the field pattern of the resonant TM410 mode, we found that the plasma density increased about 40%˜50% from 1.0˜1.1 × 1011 cm-3 to ˜1.5 × 1011 cm-3 at the same incident power of 2.5 kW, compared with the previous results with the launcher having 6 holes in the hexagonal geometry. It is also noted that the electron density changes almost linearly with the incident wave power without any mode jumps.

Sustaining GHz oscillation of carbon nanotube based oscillators via a MHz frequency excitation

NASA Astrophysics Data System (ADS)

Motevalli, Benyamin; Taherifar, Neda; Zhe Liu, Jefferson

2016-05-01

There have been intensive studies to investigate the properties of gigahertz nano-oscillators based on multi-walled carbon nanotubes (MWCNTs). Many of these studies, however, revealed that the unique telescopic translational oscillations in such devices would damp quickly due to various energy dissipation mechanisms. This challenge remains the primary obstacle against its practical applications. Herein, we propose a design concept in which a GHz oscillation could be re-excited by a MHz mechanical motion. This design involves a triple-walled CNT, in which sliding of the longer inner tube at a MHz frequency can re-excite and sustain a GHz oscillation of the shorter middle tube. Our molecular dynamics (MD) simulations prove this design concept at ˜10 nm scale. A mathematical model is developed to explore the feasibility at a larger size scale. As an example, in an oscillatory system with the CNT’s length above 100 nm, the high oscillatory frequency range of 1.8-3.3 GHz could be excited by moving the inner tube at a much lower frequency of 53.4 MHz. This design concept together with the mechanical model could energize the development of GHz nano-oscillators in miniaturized electro-mechanical devices.

Cosmic rays energy determination by radio emission registration method at frequency 30-35 MHz

NASA Astrophysics Data System (ADS)

Knurenko, S. P.; Petrov, I. S.

2017-11-01

The study of cosmic rays (CR) of ultrahigh energies first of all requires an estimate of the energy, the spectrum in terms of energies, masses, and the anisotropy of the arrival of primary particles. This can only be done by calculating the energies of all the secondary particles formed during the interaction of the primary particle with the nuclei of the air atoms [1]. First of all, this is the registration of Cherenkov and ionization radiation [2, 3]. According to model calculations, the loss of ionization of air by particles is spent up to 80% of the total energy of the primary particle [4]. The rest of the energy is spent on nuclear interactions of hadrons (nucleons) and is carried away by high-energy muons at sea level. In the hybrid registration of air showers, i.e. electron, muon, and Cherenkov components, we can empirically estimate the energy of the primary CR particle. Such a method has been developed and is being used to this day at the Yakutsk complex installation of the EAS. A detailed description of this method is given in [5, 6]. As an alternative to the energy balance method, we describe below the method of independent estimation of E0 obtained by measuring the radio emission of EAS at the frequency of 30-35 MHz at the Yakutsk array.

Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears.

PubMed

Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

2016-07-26

In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor.

Design of a New Built-in UHF Multi-Frequency Antenna Sensor for Partial Discharge Detection in High-Voltage Switchgears

PubMed Central

Zhang, Xiaoxing; Cheng, Zheng; Gui, Yingang

2016-01-01

In this study a new built-in ultrahigh frequency (UHF) antenna sensor was designed and applied in a high-voltage switchgear for partial discharge (PD) detection. The casing of the switchgear was initially used as the ground plane of the antenna sensor, which integrated the sensor into the high-voltage switchgear. The Koch snowflake patch was adopted as the radiation patch of the antenna to overcome the disadvantages of common microstrip antennas, and the feed position and the dielectric layer thickness were simulated in detail. Simulation results show that the antenna sensor possessed four resonant points with good impedance matching from 300 MHz to 1000 MHz, and it also presented good multi-frequency performance in the entire working frequency band. PD detection experiments were conducted in the high-voltage switchgear, and the fabricated antenna sensor was effectively built into the high-voltage switchgear. In order to reflect the advantages of the built-in antenna sensor, another external UHF antenna sensor was used as a comparison to simultaneously detect PD. Experimental results demonstrated that the built-in antenna sensor possessed high detection sensitivity and strong anti-interference capacity, which ensured the practicability of the design. In addition, it had more high-voltage switchgear PD detection advantages than the external sensor. PMID:27472331

Possible Explanation for Cancer in Rats due to Cell Phone Radio Frequency Radiation

NASA Astrophysics Data System (ADS)

Feldman, Bernard J.

Very recently, the National Toxicology Program reported a correlation between exposure to whole body 900 MHz radio frequency radiation and cancer in the brains and hearts of Sprague Dawley male rats. Assuming that the National Toxicology Program is statistically significant, I propose the following explanation for these results. The neurons around the brain and heart form closed electrical circuits and, following Faraday's Law, 900 MHz radio frequency radiation induces 900 MHz electrical currents in these neural circuits. In turn, these 900 MHz currents in the neural circuits generate sufficient localized heat in the neural cells to shift the equilibrium concentration of carcinogenic radicals to higher levels and thus, to higher incidences of cancer.

A MHz speed wavelength sweeping for ultra-high speed FBG interrogation

NASA Astrophysics Data System (ADS)

Kim, Gyeong Hun; Lee, Hwi Don; Eom, Tae Joong; Jeong, Myung Yung; Kim, Chang-Seok

2015-09-01

We demonstrated a MHz speed wavelength-swept fiber laser based on the active mode locking (AML) technique and applied to interrogation system of an array of fiber Bragg grating (FBG) sensors. MHz speed wavelength sweeping of wavelength-swept fiber laser can be obtained by programmable frequency modulation of the semiconductor optical amplifier (SOA) without any wavelength tunable filter. Both static and dynamic strain measurement of FBG sensors were successfully characterized with high linearity of an R-square value of 0.9999 at sweeping speed of 50 kHz.

Study of cavity type antenna structure of large-area 915 MHz ultra-high frequency wave plasma device based on three-dimensional finite difference time-domain analysis

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

Chang, Xijiang; Graduate School of Science and Engineering, Shizuoka University, 3-5-1 Johoku, Hamamatsu 432-8561; Kunii, Kazuki

2013-11-14

A large-area planar plasma source with a resonant cavity type launcher driven by a 915 MHz ultra-high frequency wave was developed. Theoretical analysis with the three-dimensional finite difference time-domain simulation was carried out to determine the optimized launcher structure by analyzing the resonant transverse magnetic mode in the resonant cavity. Numerical result expects that the resonant electric field distribution inside the cavity dominantly consists of the TM{sub 410} mode. The resonant cavity type launcher having 8 holes in an octagonal geometry was designed to fit the resonant transverse magnetic mode. Adjusting 8 hole positions of the launcher to the fieldmore » pattern of the resonant TM{sub 410} mode, we found that the plasma density increased about 40%∼50% from 1.0∼1.1 × 10{sup 11} cm{sup −3} to ∼1.5 × 10{sup 11} cm{sup −3} at the same incident power of 2.5 kW, compared with the previous results with the launcher having 6 holes in the hexagonal geometry. It is also noted that the electron density changes almost linearly with the incident wave power without any mode jumps.« less

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

DIFFERENTIAL EFFECTS OF 200, 591, AND 2,450 MHZ RADIATION ON RAT BRAIN ENERGY METABOLISM

EPA Science Inventory

Three key compounds in brain metabolism have been measured during and after exposure to continuous wave radiofrequency radiation at 200, 591, and 2,450 MHz. Frequency-dependent changes have been found for all three compounds. Changes in NADH fluorescence have been measured on the...

Harmful effects of 41 and 202 MHz radiations on some body parts and tissues.

PubMed

Kumar, Vijay; Vats, R P; Pathak, P P

2008-08-01

Many types of invisible electromagnetic waves are produced in our atmosphere. When these radiations penetrate our body, electric fields are induced inside the body, resulting in the absorption of power, which is different for different body parts and also depends on the frequency of radiations. Higher power absorption may result into health problems. In this communication, effects of electromagnetic waves (EMW) of 41 and 202 MHz frequencies transmitted by the TV tower have been studied on skin, muscles, bone and fat of human. Using international standards for safe exposure limits of specific absorption rate (SAR), we have found the safe distance from TV transmission towers for two frequencies. It is suggested that transmission towers should be located away from the thickly populated areas and people should keep away from the transmission towers, as they radiate electromagnetic radiations that are harmful to some parts/tissues of body.

Effects of acute and chronic exposure to both 900 MHz and 2100 MHz electromagnetic radiation on glutamate receptor signaling pathway.

PubMed

Gökçek-Saraç, Çiğdem; Er, Hakan; Kencebay Manas, Ceren; Kantar Gok, Deniz; Özen, Şükrü; Derin, Narin

2017-09-01

To demonstrate the molecular effects of acute and chronic exposure to both 900 and 2100 MHz radiofrequency electromagnetic radiation (RF-EMR) on the hippocampal level/activity of some of the enzymes - including PKA, CaMKIIα, CREB, and p44/42 MAPK - from N-methyl-D-aspartate receptor (NMDAR)-related signaling pathways. Rats were divided into the following groups: sham rats, and rats exposed to 900 and 2100 MHz RF-EMR for 2 h/day for acute (1 week) or chronic (10 weeks), respectively. Western blotting and activity measurement assays were used to assess the level/activity of the selected enzymes. The obtained results revealed that the hippocampal level/activity of selected enzymes was significantly higher in the chronic groups as compared to the acute groups at both 900 and 2100 MHz RF-EMR exposure. In addition, hippocampal level/activity of selected enzymes was significantly higher at 2100 MHz RF-EMR than 900 MHz RF-EMR in both acute and chronic groups. The present study provides experimental evidence that both exposure duration (1 week versus 10 weeks) and different carrier frequencies (900 vs. 2100 MHz) had different effects on the protein expression of hippocampus in Wistar rats, which might encourage further research on protection against RF-EMR exposure.

[The influence of ultrahigh-frequency electromagnetic radiation and low-intensity laser radiation on the body core temperature and basal metabolism in rats with systemic inflammation].

PubMed

Zhavoronok, I P; Molchanova, A Iu; Ulashik, V S

2012-01-01

The effects of ultrahigh-frequency electromagnetic radiation (UHF EMR) and low-intensity laser irradiation (LILI) on the body and skin temperature, oxygen consumption, production of carbon dioxide and heat release were investigated in the experiments on intact rats and during LPS-induced polyphasic fever. It was found that UHF EMR with the wavelength of 4,9 mm, 5,6 mm or 7,1 mm and LILI with the wavelength of 0.47 microm, 0.67 microm and 0.87 microm caused modulation of basal metabolism and thermal response to systemically administered lipopolysaccharide (LPS). These findings suggest that the most pronounced antipyretic and hypometabolic effects were observed after the treatment with UHF EMR at 7,1 mm and LILI at 470 microm.

Heat-power working regimes of a high-frequency (0.44 MHz) 1000-kW induction plasmatron

NASA Astrophysics Data System (ADS)

Gorbanenko, V. M.; Farnasov, G. A.; Lisafin, A. B.

2015-12-01

The energy working regimes of a superpower high-frequency induction (HFI) plasmatron with a high-frequency (HF) generator are studied. The HFI plasmatron with a power of 1000 kVA and a working frequency of 440 kHz, in which air is used as a plasma-forming gas, can be used for treatment of various oxide powder materials. The energy regimes substantially influence finish products and their costs. Various working regimes of the HFI plasma unit and the following characteristics are studied: the dependence of the vibration power on the anode power, the dependence of the power losses on the anode power at various of plasma-forming gas flow rates, and the coefficients of efficiency of the plasmatron and the HFI-plasma unit at various powers. The effect of the plasma-forming gas flow rate on the bulk temperature is determined.

Effects of GSM modulated radio-frequency electromagnetic radiation on permeability of blood-brain barrier in male & female rats.

PubMed

Sırav, Bahriye; Seyhan, Nesrin

2016-09-01

With the increased use of mobile phones, their biological and health effects have become more important. Usage of mobile phones near the head increases the possibility of effects on brain tissue. This study was designed to investigate the possible effects of pulse modulated 900MHz and 1800MHz radio-frequency radiation on the permeability of blood-brain barrier of rats. Study was performed with 6 groups of young adult male and female wistar albino rats. The permeability of blood-brain barrier to intravenously injected evans blue dye was quantitatively examined for both control and radio-frequency radiarion exposed groups. For male groups; Evans blue content in the whole brain was found to be 0.08±0.01mg% in the control, 0.13±0.03mg% in 900MHz exposed and 0.26±0.05mg% in 1800MHz exposed animals. In both male radio-frequency radiation exposed groups, the permeability of blood-brain barrier found to be increased with respect to the controls (p<0.01). 1800MHz pulse modulated radio-frequency radiation exposure was found more effective on the male animals (p<0.01). For female groups; dye contents in the whole brains were 0.14±0.01mg% in the control, 0.24±0.03mg% in 900MHz exposed and 0.14±0.02mg% in 1800MHz exposed animals. No statistical variance found between the control and 1800MHz exposed animals (p>0.01). However 900MHz pulse modulated radio-frequency exposure was found effective on the permeability of blood-brain barrier of female animals. Results have shown that 20min pulse modulated radio-frequency radiation exposure of 900MHz and 1800MHz induces an effect and increases the permeability of blood-brain barrier of male rats. For females, 900MHz was found effective and it could be concluded that this result may due to the physiological differences between female and male animals. The results of this study suggest that mobile phone radation could lead to increase the permeability of blood-brain barrier under non-thermal exposure levels. More studies are needed

GROWTH AND DEVELOPMENT OF MICE OFFSPRING AFTER IRRADIATION IN UTERO WITH 2,450-MHZ MICROWAVES

EPA Science Inventory

Mice offspring irradiated in utero with 2,450-MHz radio-frequency (RF) radiation at 0 or 28 mW/cm. sq. (whole-body averaged specific absorption rate = 0 or 16.5 W/kg) for 100 minutes daily on days 6 through 17 of gestation were evaluated for maturation and development on days 1, ...

Design of 1 MHz Solid State High Frequency Power Supply

NASA Astrophysics Data System (ADS)

Parmar, Darshan; Singh, N. P.; Gajjar, Sandip; Thakar, Aruna; Patel, Amit; Raval, Bhavin; Dhola, Hitesh; Dave, Rasesh; Upadhay, Dishang; Gupta, Vikrant; Goswami, Niranjan; Mehta, Kush; Baruah, Ujjwal

2017-04-01

High Frequency Power supply (HFPS) is used for various applications like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600 W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with Class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50ohm respectively. This paper describes the conceptual design of a 200 kW high frequency power supply and experimental results of the prototype 600 W, 1 MHz source.

Potential GPRS 900/180-MHz and WCDMA 1900-MHz interference to medical devices.

PubMed

Iskra, Steve; Thomas, Barry W; McKenzie, Ray; Rowley, Jack

2007-10-01

This study compared the potential for interference to medical devices from radio frequency (RF) fields radiated by GSM 900/1800-MHz, general packet radio service (GPRS) 900/1800-MHz, and wideband code division multiple access (WCDMA) 1900-MHz handsets. The study used a balanced half-wave dipole antenna, which was energized with a signal at the standard power level for each technology, and then brought towards the medical device while noting the distance at which interference became apparent. Additional testing was performed with signals that comply with the requirements of the international immunity standard to RF fields, IEC 61000-4-3. The testing provides a sense of the overall interference impact that GPRS and WCDMA (frequency division duplex) may have, relative to current mobile technologies, and to the internationally recognized standard for radiated RF immunity. Ten medical devices were tested: two pulse oximeters, a blood pressure monitor, a patient monitor, a humidifier, three models of cardiac defibrillator, and two models of infusion pump. Our conclusion from this and a related study on consumer devices is that WCDMA handsets are unlikely to be a significant interference threat to medical electronics at typical separation distances.

[The ultrastructural manifestations of the regenerative processes in the Sertoli cells under the action of low-intensity electromagnetic radiation in the rats subjected to stress].

PubMed

Korolev, Iu N; Geniatulina, M S; Nikulina, L A; Mikhaĭlik, L V

2015-01-01

The experiments on the outbred female rats using the electron microscopic technique have demonstrated that the application of ultrahigh frequency low-intensity electromagnetic radiation (LIEMR) with a flux density below 1 mCW/Cm2 and a frequency of approximately 1,000 MHz in the regime of primary prophylaxis and therapeutic-preventive action suppressed the development of the post-stress pathological ultrastructural changes and increased the activity of the regenerative processes in the Sertoli cells. It was shown that the developing adaptive and compensatory changes in the Sertoli cells most frequently involve the energy-producing structures (mitochondria) that undergo the enlargement of their average and total dimensions. Simultaneously, the amount of granular endoplasmic reticulum and the number of ribosomes increased while the intracellular links between the organelles strengthened and the reserve potential of the cells improved. It is concluded that the observed effects may be due to the action of both local and systemic regulation mechanisms.

Improved Anatomical Specificity of Non-invasive Neuro-stimulation by High Frequency (5 MHz) Ultrasound

NASA Astrophysics Data System (ADS)

Li, Guo-Feng; Zhao, Hui-Xia; Zhou, Hui; Yan, Fei; Wang, Jing-Yao; Xu, Chang-Xi; Wang, Cong-Zhi; Niu, Li-Li; Meng, Long; Wu, Song; Zhang, Huai-Ling; Qiu, Wei-Bao; Zheng, Hai-Rong

2016-04-01

Low frequency ultrasound (<1 MHz) has been demonstrated to be a promising approach for non-invasive neuro-stimulation. However, the focal width is limited to be half centimeter scale. Minimizing the stimulation region with higher frequency ultrasound will provide a great opportunity to expand its application. This study first time examines the feasibility of using high frequency (5 MHz) ultrasound to achieve neuro-stimulation in brain, and verifies the anatomical specificity of neuro-stimulation in vivo. 1 MHz and 5 MHz ultrasound stimulation were evaluated in the same group of mice. Electromyography (EMG) collected from tail muscles together with the motion response videos were analyzed for evaluating the stimulation effects. Our results indicate that 5 MHz ultrasound can successfully achieve neuro-stimulation. The equivalent diameter (ED) of the stimulation region with 5 MHz ultrasound (0.29 ± 0.08 mm) is significantly smaller than that with 1 MHz (0.83 ± 0.11 mm). The response latency of 5 MHz ultrasound (45 ± 31 ms) is also shorter than that of 1 MHz ultrasound (208 ± 111 ms). Consequently, high frequency (5 MHz) ultrasound can successfully activate the brain circuits in mice. It provides a smaller stimulation region, which offers improved anatomical specificity for neuro-stimulation in a non-invasive manner.

TEM Cell Testing of Cable Noise Reduction Techniques From 2 MHz to 200 MHz - Part 1

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Evans, William C.; Reed, Joshua L.; Shimp, Samuel K.; Fitzpatrick, Fred D.

2008-01-01

This paper presents empirical results of cable noise reduction techniques as demonstrated in a TEM cell operating with radiated fields from 2 - 200 MHz. It is the first part of a two-paper series. This first paper discusses cable types and shield connections. In the second paper, the effects of load and source resistances and chassis connections are examined. For each topic, well established theories are compared to data from a real-world physical system. Finally, recommendations for minimizing cable susceptibility (and thus cable emissions) are presented. There are numerous papers and textbooks that present theoretical analyses of cable noise reduction techniques. However, empirical data is often targeted to low frequencies (e.g. <50 KHz) or high frequencies (>100 MHz). Additionally, a comprehensive study showing the relative effects of various noise reduction techniques is needed. These include the use of dedicated return wires, twisted wiring, cable shielding, shield connections, changing load or source impedances, and implementing load- or source-to-chassis isolation. We have created an experimental setup that emulates a real-world electrical system, while still allowing us to independently vary a host of parameters. The goal of the experiment was to determine the relative effectiveness of various noise reduction techniques when the cable is in the presence of radiated emissions from 2 MHz to 200 MHz. The electronic system (Fig. 1) consisted of two Hammond shielded electrical enclosures, one containing the source resistance, and the other containing the load resistance. The boxes were mounted on a large aluminium plate acting as the chassis. Cables connecting the two boxes measured 81 cm in length and were attached to the boxes using standard D38999 military-style connectors. The test setup is shown in Fig. 2. Electromagnetic fields were created using an HP8657B signal generator, MiniCircuits ZHL-42W-SMA amplifier, and an EMCO 5103 TEM cell. Measurements were

Global Sky Model (GSM): A Model of Diffuse Galactic Radio Emission from 10 MHz to 100 GHz

NASA Astrophysics Data System (ADS)

de Oliveira-Costa, Angelica; Tegmark, Max; Gaensler, B. M.; Jonas, Justin; Landecker, T. L.; Reich, Patricia

2010-11-01

Understanding diffuse Galactic radio emission is interesting both in its own right and for minimizing foreground contamination of cosmological measurements. Cosmic Microwave Background experiments have focused on frequencies > 10 GHz, whereas 21 cm tomography of the high redshift universe will mainly focus on < 0.2 GHz, for which less is currently known about Galactic emission. Motivated by this, we present a global sky model derived from all publicly available total power large-area radio surveys, digitized with optical character recognition when necessary and compiled into a uniform format, as well as the new Villa Elisa data extending the 1.4 GHz map to the entire sky. We quantify statistical and systematic uncertainties in these surveys by comparing them with various global multi-frequency model fits. We find that a principal component based model with only three components can fit the 11 most accurate data sets (at 10, 22, 45 & 408 MHz and 1.4, 2.3, 23, 33, 41, 61, 94 GHz) to an accuracy around 1%-10% depending on frequency and sky region. The data compilation and software returning a predicted all-sky map at any frequency from 10 MHz to 100 GHz are publicly available at the link below.

BLAZAR SPECTRAL PROPERTIES AT 74 MHz

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

Massaro, F.; Funk, S.; Giroletti, M.

2013-10-01

Blazars are the most extreme class of active galactic nuclei. Despite a previous investigation at 102 MHz for a small sample of BL Lac objects and our recent analysis of blazars detected in the Westerbork Northern Sky Survey, a systematic study of the blazar spectral properties at frequencies below 100 MHz has been never carried out. In this paper, we present the first analysis of the radio spectral behavior of blazars based on the recent Very Large Array Low-frequency Sky Survey (VLSS) at 74 MHz. We search for blazar counterparts in the VLSS catalog, confirming that they are detected atmore » 74 MHz. We then show that blazars present radio-flat spectra (i.e., radio spectral indices of ∼0.5) when evaluated, which also about an order of magnitude in frequency lower than previous analyses. Finally, we discuss the implications of our findings in the context of the blazars-radio galaxies connection since the low-frequency radio data provide a new diagnostic tool to verify the expectations of the unification scenario for radio-loud active galaxies.« less

Electron density modulation in a pulsed dual-frequency (2/13.56 MHz) dual-antenna inductively coupled plasma discharge

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

Sirse, Nishant, E-mail: nishant.sirse@dcu.ie; Mishra, Anurag; Yeom, Geun Y.

The electron density, n{sub e}, modulation is measured experimentally using a resonance hairpin probe in a pulsed, dual-frequency (2/13.56 MHz), dual-antenna, inductively coupled plasma discharge produced in argon-C{sub 4}F{sub 8} (90–10) gas mixtures. The 2 MHz power is pulsed at a frequency of 1 kHz, whereas 13.56 MHz power is applied in continuous wave mode. The discharge is operated at a range of conditions covering 3–50 mTorr, 100–600 W 13.56 MHz power level, 300–600 W 2 MHz peak power level, and duty ratio of 10%–90%. The experimental results reveal that the quasisteady state n{sub e} is greatly affected by the 2 MHz power levels and slightly affected by 13.56 MHzmore » power levels. It is observed that the electron density increases by a factor of 2–2.5 on increasing 2 MHz power level from 300 to 600 W, whereas n{sub e} increases by only ∼20% for 13.56 MHz power levels of 100–600 W. The rise time and decay time constant of n{sub e} monotonically decrease with an increase in either 2 or 13.56 MHz power level. This effect is stronger at low values of 2 MHz power level. For all the operating conditions, it is observed that the n{sub e} overshoots at the beginning of the on-phase before relaxing to a quasisteady state value. The relative overshoot density (in percent) depends on 2 and 13.56 MHz power levels. On increasing gas pressure, the n{sub e} at first increases, reaching to a maximum value, and then decreases with a further increase in gas pressure. The decay time constant of n{sub e} increases monotonically with pressure, increasing rapidly up to 10 mTorr gas pressure and at a slower rate of rise to 50 mTorr. At a fixed 2/13.56 MHz power level and 10 mTorr gas pressure, the quasisteady state n{sub e} shows maximum for 30%–40% duty ratio and decreases with a further increase in duty ratio.« less

Resonance Frequency Readout Circuit for a 900 MHz SAW Device

PubMed Central

Liu, Heng; Zhang, Chun; Weng, Zhaoyang; Guo, Yanshu; Wang, Zhihua

2017-01-01

A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency searching strategy has been proposed based on the fact that the SAW device phase-frequency response crosses zero monotonically around the resonance frequency. A dedicated instant phase difference detecting circuit is adopted to facilitate the fast SAR operation for resonance frequency searching. The readout circuit has been implemented in 180 nm CMOS technology with a core area of 3.24 mm2. In the experiment, it works with a 900 MHz SAW resonator with a quality factor of Q = 130. Experimental results show that the readout circuit consumes 7 mW power from 1.6 V supply. The frequency resolution is 733 Hz, and the relative accuracy is 0.82 ppm, and it takes 0.48 ms to complete one measurement. Compared to the previous results in the literature, this work has achieved the shortest measurement time with a trade-off between measurement accuracy and measurement time. PMID:28914799

Resonance Frequency Readout Circuit for a 900 MHz SAW Device.

PubMed

Liu, Heng; Zhang, Chun; Weng, Zhaoyang; Guo, Yanshu; Wang, Zhihua

2017-09-15

A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency searching strategy has been proposed based on the fact that the SAW device phase-frequency response crosses zero monotonically around the resonance frequency. A dedicated instant phase difference detecting circuit is adopted to facilitate the fast SAR operation for resonance frequency searching. The readout circuit has been implemented in 180 nm CMOS technology with a core area of 3.24 mm². In the experiment, it works with a 900 MHz SAW resonator with a quality factor of Q = 130. Experimental results show that the readout circuit consumes 7 mW power from 1.6 V supply. The frequency resolution is 733 Hz, and the relative accuracy is 0.82 ppm, and it takes 0.48 ms to complete one measurement. Compared to the previous results in the literature, this work has achieved the shortest measurement time with a trade-off between measurement accuracy and measurement time.

Radiation Hardness of Efratom M-100 Rubidium Frequency Standard

DTIC Science & Technology

1982-12-01

h i ghes t f l uence o f 6.15 x 1012n/crn2 t h e norma l i zed ac pho tocur ren ts were about 702 o f t he normal ized dc photo- c u r r...100, FRK, M-1000. Pyrex ( t r ade name of Corning Glass) . e Cells produced i n Munich use Schott Duran 50 g lass which i s nearly ident ica l

Radiation sterilization of medical devices. Effects of ionizing radiation on ultra-high molecular-weight polyethylene

NASA Astrophysics Data System (ADS)

Buchalla, R.; Schüttler, C.; Bögl, K. W.

1995-02-01

Sterilization by ionizing radiation has become, next to ethylene oxide treament, the most important "cold" sterilization process for medical devices made from plastics. The effects of ionizing radiation on the most important polymer for medical devices, ultra-high molecular-weight polyethylene, are briefly described in this review.

CMOS-Compatible SOI MESFETS for Radiation-Hardened DC-to-DC Converters

NASA Technical Reports Server (NTRS)

Thornton, Trevor; Lepkowski, William; Wilk, Seth

2013-01-01

A radiation-tolerant transistor switch has been developed that can operate between 196 and +150 C for DC-to-DC power conversion applications. A prototype buck regulator component was demonstrated to be performing well after a total ionizing dose of 300 krad(Si). The prototype buck converters showed good efficiencies at ultra-high switching speeds in the range of 1 to 10 MHz. Such high switching frequency will enable smaller, lighter buck converters to be developed as part of the next project. Switching regulators are widely used in commercial applications including portable consumer electronics.

900 MHz radiation does not induce micronucleus formation in different cell types.

PubMed

Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Schrader, Thorsten; Stopper, Helga

2012-07-01

The exposure of the population to non-ionising electromagnetic radiation is still increasing, mainly due to mobile communication. Whether low-intensity electromagnetic fields can cause other effects apart from heating has been a subject of debate. One of the effects, which were proposed to be caused by mobile phone radiation, is the occurrence of mitotic disturbances. The aim of this study was to investigate possible consequences of these mitotic disturbances as manifest genomic damage, i.e. micronucleus induction. Cells were irradiated at a frequency of 900 MHz, which is located in one of the main frequency bands applied for mobile communication. Two cell types were used, HaCaT cells as human cells and A(L) cells (human-hamster hybrid cells), in which mitotic disturbances had been reported to occur. After different post-exposure incubation periods, cells were fixed and micronucleus frequencies were evaluated. Both cell types did not show any genomic damage after exposure. To adapt the protocol for the micronucleus test into the direction of the protocol for mitotic disturbances, the post-exposure incubation period was reduced and exposure time was extended to one cell cycle length. This did not result in any increase of the genomic damage. In conclusion, micronucleus induction was not observed as a consequence of exposure to non-ionising radiation, even though this agent was reported to cause mitotic disturbances under similar experimental conditions.

Investigation of a quadrupole ultra-high vacuum ion pump

NASA Technical Reports Server (NTRS)

Schwarz, H. J.

1974-01-01

The new nonmagnetic ion pump resembles the quadrupole ionization gage. The dimensions are larger, and hyperbolically shaped electrodes replace the four rods. Their surfaces follow y sq. = 36 + x sq. (x, y in centimeters). The electrodes, 55 cm long, are positioned lengthwise in a tube. At one end a cathode emits electrons; at the other end a narrowly wound flat spiral of tungsten clad with titanium on cathode potential can be heated for titanium evaporation. Electrons accelerated by a dc potential of the surface electrodes oscillate between the ends on rotational trajectories, if a high frequency potential superimposed on the dc potential is properly adjusted. Pumping speeds (4-100 liter/sec) for different gases at different peak voltages (1000-3000V) at corresponding frequencies (57-100 MHz), and at different pressures 0.00001 to the minus 9 power Torr were observed. The lowest pressure reached was below 10 to the minus 10 power Torr.

Survival of Chinese Hamster Ovary Cells Following Ultrahigh Dose Rate Electron and Bremsstrahlung Radiation

DTIC Science & Technology

1990-04-01

and a stepped lead flattening filter. The electron energy used for these studies was 13 MeV. Dosimetry was performed by the Health Physics Division...VolI LJSAFSAPA-TR-90-4 AD-A222 722 SURVIVAL OF CHINESE HAMSTER OVARY CELLS FOLLOWING ULTRAHIGH DOSE RATE ELECTRON AND BREMISSTRAHLUNG RADIATION...Include Security ;a!. iatcn) Survival of Chinese Hamster Ovary Cells Following Ultrahigh Dose Rate Electron and Bremsstrahlung Radiation 12 PERSONAL

Spectral-Temporal Evolution of Low-Frequency Pulsations in the Microwave Radiation of Solar Flares

NASA Astrophysics Data System (ADS)

Zaitsev, V. V.; Kislyakov, A. G.; Urpo, S.; Stepanov, A. V.; Shkelev, E. I.

2003-10-01

Low-frequency pulsations of 22 and 37 GHz microwave radiation detected during solar flares are analyzed. Several microwave bursts observed at the Metsähovi Radio Observatory are studied with time resolutions of 100 and 50 ms. A fast Fourier transformation with a sliding window and the Wigner-Ville method are used to obtain frequency-time diagrams for the low-frequency pulsations, which are interpreted as natural oscillations of coronal magnetic loops; the dynamical spectra of the pulsations are synthesized for the first time. Three types of low-frequency fluctuations modulating the flare microwave radiation can be distinguished in the observations. First, there are fast and slow magneto-acoustic oscillations with periods of 0.5 0.8 s and 200 280 s, respectively. The fast magneto-acoustic oscillations appear as trains of narrow-band signals with durations of 100 200 s, a positive frequency drift dν/dt=0.25 MHz/min, and frequency splitting δν=0.01 0.05 Hz. Second, there are natural oscillations of the coronal magnetic loops as equivalent electrical circuits. These oscillations have periods of 0.5 10 s and positive or negative frequency drift rates dν/dt=8×10-3 Hz/min or dν/dt=-1.3×10-2 Hz/min, depending on the phase of the radio outburst. Third, there are modulations of the microwave radiation by short periodic pulses with a period of 20 s. The dynamical spectra of the low-frequency pulsations supply important information about the parameters of the magnetic loops: the ratio of the loop radius to its length r/L≈0.1, the plasma parameter β≈10-3, the ratio of the plasma densities outside and inside the loop ρe/ρi≈10-2, and the electrical current flowing along the loop I≈1012 A.

Blood-brain barrier disruption by continuous-wave radio frequency radiation.

PubMed

Sirav, Bahriye; Seyhan, Nesrin

2009-01-01

The increasing use of cellular phones and the increasing number of associated base stations are becoming a widespread source of non ionizing electromagnetic radiation. Some biological effects are likely to occur even at low-level EM fields. This study was designed to investigate the effects of 900 and 1,800 MHz Continuous Wave Radio Frequency Radiation (CW RFR) on the permeability of Blood Brain Barrier (BBB) of rats. Results have shown that 20 min RFR exposure of 900 and 1,800 MHz induces an effect and increases the permeability of BBB of male rats. There was no change in female rats. The scientific evidence on RFR safety or harm remains inconclusive. More studies are needed to demonstrate the effects of RFR on the permeability of BBB and the mechanisms of that breakdown.

170-MHz electrodeless quartz crystal microbalance biosensor: capability and limitation of higher frequency measurement.

PubMed

Ogi, Hirotsugu; Nagai, Hironao; Naga, Hironao; Fukunishi, Yuji; Hirao, Masahiko; Nishiyama, Masayoshi

2009-10-01

We develop a highly sensitive quartz crystal microbalance (QCM) biosensor with a fundamental resonance frequency of 170 MHz. A naked AT-cut quartz plate of 9.7 microm thick is set in a sensor cell. Its shear vibration is excited by the line wire, and the vibration signals are detected by the other line wire, achieving the noncontacting measurement of the resonance frequency. The mass sensitivity of the 170 MHz QCM biosensor is 15 pg/(cm2 Hz), which is better than that of a conventional 5 MHz QCM by 3 orders of magnitude. Its high sensitivity is confirmed by detecting human immunoglobulin G (hIgG) via Staphylococcus protein A immobilized nonspecifically on both surfaces of the quartz plate. The detection limit is 0.5 pM. Limitation of the high-frequency QCM measurement is then theoretically discussed with a continuum mechanics model for a plate with point masses connected by elastic springs. The result indicates that a QCM measurement will break down at frequencies one-order-of-magnitude higher than the local resonance frequency at specific binding cites.

Solar U- and J- Bursts at the Frequencies 10-30MHz

NASA Astrophysics Data System (ADS)

Dorovskyy, V. V.; Melnik, V. N.; Konovalenko, A. A.; Abranin, E. P.; Rucker, H. O.; Lecacheux, A.

2006-08-01

In the present report we discuss the results of observations of solar U- and J- bursts over the frequency range 10-30MHz, which have been obtained within the framework of an international observational campaign in June - August, 2004 at the radio telescope UTR-2 (Kharkov, Ukraine). We succeed to observe these types of bursts for the first time at such a low frequencies due to combination of large effective area of the radio telescope and high sensitivity of the new back-end. During June - August, 2004 about 30 U- and J- bursts were registered, and only 5 of them were confidently identified as U-bursts that may speak about the relative sparsity of the latter at mentioned frequencies. Both the isolated bursts and their sequences were observed. On average the turning frequencies lay in the range 10-22 MHz that corresponds to the arches heliocentric heights of 1.6-2.2 solar radii. In some sequences the bursts turning frequency was stable that may indicate the arch stability, while in others the turning frequency had tendency to vary from burst to burst. Durations of U- and J- bursts did not differ from those of usual Type III bursts (3-7s), while the drift rates of an ascending arm (on the average -1MHz/ s) was a little bit lower, than those of ordinary Type III bursts in this range. The harmonic structure of U- and J- bursts, and also Jb-J pairs (analogous to IIIb-III pairs) were registered. Also L-shaped bursts (Leblanc and Hoyos, 1985) were recorded. A specific feature of L-shaped bursts is prolonged zero-drift region on their dynamic spectra. The sizes and configurations of the arches were estimated on the base of obtained data. Possible explanations of the observed properties of U- and J- bursts are discussed.

Effects of GSM-Frequency Electromagnetic Radiation on Some Physiological and Biochemical Parameters in Rats.

PubMed

Khirazova, E E; Baizhumanov, A A; Trofimova, L K; Deev, L I; Maslova, M V; Sokolova, N A; Kudryashova, N Yu

2012-10-01

Single exposure of white outbred rats to electromagnetic radiation with a frequency 905 MHz (GSM frequency) for 2 h increased anxiety, reduced locomotor, orientation, and exploration activities in females and orientation and exploration activities in males. Glucocorticoid levels and antioxidant system activity increased in both males and females. In addition to acute effects, delayed effects of radiation were observed in both males and females 1 day after the exposure. These results demonstrated significant effect of GSM-range radiation on the behavior and activity of stress-realizing and stress-limiting systems of the body.

Ultra-widefield retinal MHz-OCT imaging with up to 100 degrees viewing angle.

PubMed

Kolb, Jan Philip; Klein, Thomas; Kufner, Corinna L; Wieser, Wolfgang; Neubauer, Aljoscha S; Huber, Robert

2015-05-01

We evaluate strategies to maximize the field of view (FOV) of in vivo retinal OCT imaging of human eyes. Three imaging modes are tested: Single volume imaging with 85° FOV as well as with 100° and stitching of five 60° images to a 100° mosaic (measured from the nodal point). We employ a MHz-OCT system based on a 1060nm Fourier domain mode locked (FDML) laser with a depth scan rate of 1.68MHz. The high speed is essential for dense isotropic sampling of the large areas. Challenges caused by the wide FOV are discussed and solutions to most issues are presented. Detailed information on the design and characterization of our sample arm optics is given. We investigate the origin of an angle dependent signal fall-off which we observe towards larger imaging angles. It is present in our 85° and 100° single volume images, but not in the mosaic. Our results suggest that 100° FOV OCT is possible with current swept source OCT technology.

Ultra-widefield retinal MHz-OCT imaging with up to 100 degrees viewing angle

PubMed Central

Kolb, Jan Philip; Klein, Thomas; Kufner, Corinna L.; Wieser, Wolfgang; Neubauer, Aljoscha S.; Huber, Robert

2015-01-01

We evaluate strategies to maximize the field of view (FOV) of in vivo retinal OCT imaging of human eyes. Three imaging modes are tested: Single volume imaging with 85° FOV as well as with 100° and stitching of five 60° images to a 100° mosaic (measured from the nodal point). We employ a MHz-OCT system based on a 1060nm Fourier domain mode locked (FDML) laser with a depth scan rate of 1.68MHz. The high speed is essential for dense isotropic sampling of the large areas. Challenges caused by the wide FOV are discussed and solutions to most issues are presented. Detailed information on the design and characterization of our sample arm optics is given. We investigate the origin of an angle dependent signal fall-off which we observe towards larger imaging angles. It is present in our 85° and 100° single volume images, but not in the mosaic. Our results suggest that 100° FOV OCT is possible with current swept source OCT technology. PMID:26137363

Effects of 900 MHz radiofrequency radiation on skin hydroxyproline contents.

PubMed

Çam, Semra Tepe; Seyhan, Nesrin; Kavaklı, Cengiz; Çelikbıçak, Ömür

2014-09-01

The present study aimed to investigate the possible effect of pulse-modulated radiofrequency radiation (RFR) on rat skin hydroxyproline content, since skin is the first target of external electromagnetic fields. Skin hydroxyproline content was measured using liquid chromatography mass spectrometer method. Two months old male wistar rats were exposed to a 900 MHz pulse-modulated RFR at an average whole body specific absorption rate (SAR) of 1.35 W/kg for 20 min/day for 3 weeks. The radiofrequency (RF) signals were pulse modulated by rectangular pulses with a repetition frequency of 217 Hz and a duty cycle of 1:8 (pulse width 0.576 ms). A skin biopsy was taken at the upper part of the abdominal costa after the exposure. The data indicated that whole body exposure to a pulse-modulated RF radiation that is similar to that emitted by the global system for mobile communications (GSM) mobile phones caused a statistically significant increase in the skin hydroxyproline level (p = 0.049, Mann-Whitney U test). Under our experimental conditions, at a SAR less than the International Commission on Non-Ionizing Radiation Protection safety limit recommendation, there was evidence that GSM signals could alter hydroxyproline concentration in the rat skin.

In vitro fertilization of mouse ova by spermatozoa exposed isothermally to radio-frequency radiation

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

Cleary, S.F.; Liu, L.M.; Graham, R.

Mouse spermatozoa were exposed in vitro for 1 h to 27- or 2,450-MHz CW RF radiation at SARs of 0 to 90 W/kg under isothermal (37 +/- 0.2 degrees C) conditions. Exposure at either frequency to RF radiation at SARs of 50 W/kg or greater resulted in a statistically significant reduction in the ability of irradiated sperm to fertilize mouse ova in vitro (P less than .05). Over the range of SARs there was no apparent difference in the effects of 27- vs. 2,450-MHz RF radiation. There were no readily detectable exposure effects on spermatozoan morphology, ultrastructure, or capacitation. Themore » reduction of in vitro fertilization is attributed to a direct effect of RF radiation on spermatozoa rather than to heating.« less

ARM - Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers, 449 MHz Profiler(williams-449_prof)

DOE Data Explorer

Williams, Christopher; Jensen, Mike

2012-11-06

This data was collected by the NOAA 449-MHz and 2.8-GHz profilers in support of the Department of Energy (DOE) and NASA sponsored Mid-latitude Continental Convective Cloud Experiment (MC3E). The profiling radars were deployed in Northern Oklahoma at the DOE Atmospheric Radiation Mission (ARM) Southern Great Plans (SGP) Central Facility from 22 April through 6 June 2011. NOAA deployed three instruments: a Parsivel disdrometer, a 2.8-GHz profiler, and a 449-MHz profiler. The parasivel provided surface estimates of the raindrop size distribution and is the reference used to absolutely calibrate the 2.8 GHz profiler. The 2.8-GHz profiler provided unattenuated reflectivity profiles of the precipitation. The 449-MHz profiler provided estimates of the vertical air motion during precipitation from near the surface to just below the freezing level. By using the combination of 2.8-GHz and 449-MHz profiler observations, vertical profiles of raindrop size distributions can be retrieved. The profilers are often reference by their frequency band: the 2.8-GHz profiler operates in the S-band and the 449-MHz profiler operates in the UHF band. The raw observations are available as well as calibrated spectra and moments. This document describes how the instruments were deployed, how the data was collected, and the format of the archived data.

High-frequency attenuation and backscatter measurements of rat blood between 30 and 60 MHz.

PubMed

Huang, Chih-Chung

2010-10-07

There has recently been a great deal of interest in noninvasive high-frequency ultrasound imaging of small animals such as rats due to their being the preferred animal model for gene therapy and cancer research. Improving the interpretation of the obtained images and furthering the development of the imaging devices require a detailed knowledge of the ultrasound attenuation and backscattering of biological tissue (e.g. blood) at high frequencies. In the present study, the attenuation and backscattering coefficients of the rat red blood cell (RBC) suspensions and whole blood with hematocrits ranging from 6% to 40% were measured between 30 and 60 MHz using a modified substitution approach. The acoustic parameters of porcine blood under the same conditions were also measured in order to compare differences in the blood properties between these two animals. For porcine blood, both whole blood and RBC suspension were stirred at a rotation speed of 200 rpm. Three different rotation speeds of 100, 200 and 300 rpm were carried out for rat blood experiments. The attenuation coefficients of both rat and porcine blood were found to increase linearly with frequency and hematocrit (the values of coefficients of determination (r(2)) are around 0.82-0.97 for all cases). The average attenuation coefficient of rat whole blood with a hematocrit of 40% increased from 0.26 Nepers mm(-1) at 30 MHz to 0.47 Nepers mm(-1) at 60 MHz. The maximum backscattering coefficients of both rat and porcine RBC suspensions were between 10% and 15% hematocrits at all frequencies. The fourth-power dependence of backscatter on frequency was approximately valid for rat RBC suspensions with hematocrits between 6% and 40%. However, the frequency dependence of the backscatter estimate deviates from a fourth-power law for porcine RBC suspension with hematocrit higher than 20%. The backscattering coefficient plateaued for hematocrits higher than 15% in porcine blood, but for rat blood it was maximal around a

Monolithically integrated tri-axis shock accelerometers with MHz-level high resonant-frequency

NASA Astrophysics Data System (ADS)

Zou, Hongshuo; Wang, Jiachou; Chen, Fang; Bao, Haifei; Jiao, Ding; Zhang, Kun; Song, Zhaohui; Li, Xinxin

2017-07-01

This paper reports a novel monolithically integrated tri-axis high-shock accelerometer with high resonant-frequency for the detection of a broad frequency-band shock signal. For the first time, a resonant-frequency as high as about 1.4 MHz is designed for all the x-, y- and z-axis accelerometers of the integrated tri-axis sensor. In order to achieve a wide frequency-band detection performance, all the three sensing structures are designed into an axially compressed/stretched tiny-beam sensing scheme, where the p  +  -doped tiny-beams are connected into a Wheatstone bridge for piezoresistive output. By using ordinary (1 1 1) silicon wafer (i.e. non-SOI wafer), a single-wafer based fabrication technique is developed to monolithically integrate the three sensing structures for the tri-axis sensor. Testing results under high-shock acceleration show that each of the integrated three-axis accelerometers exhibit about 1.4 MHz resonant-frequency and 0.2-0.4 µV/V/g sensitivity. The achieved high frequencies for all the three sensing units make the tri-axis sensor promising in high fidelity 3D high-shock detection applications.

The Frequency Spectral Properties of Electrode-Skin Contact Impedance on Human Head and Its Frequency-Dependent Effects on Frequency-Difference EIT in Stroke Detection from 10Hz to 1MHz.

PubMed

Yang, Lin; Dai, Meng; Xu, Canhua; Zhang, Ge; Li, Weichen; Fu, Feng; Shi, Xuetao; Dong, Xiuzhen

2017-01-01

Frequency-difference electrical impedance tomography (fdEIT) reconstructs frequency-dependent changes of a complex impedance distribution. It has a potential application in acute stroke detection because there are significant differences in impedance spectra between stroke lesions and normal brain tissues. However, fdEIT suffers from the influences of electrode-skin contact impedance since contact impedance varies greatly with frequency. When using fdEIT to detect stroke, it is critical to know the degree of measurement errors or image artifacts caused by contact impedance. To our knowledge, no study has systematically investigated the frequency spectral properties of electrode-skin contact impedance on human head and its frequency-dependent effects on fdEIT used in stroke detection within a wide frequency band (10 Hz-1 MHz). In this study, we first measured and analyzed the frequency spectral properties of electrode-skin contact impedance on 47 human subjects' heads within 10 Hz-1 MHz. Then, we quantified the frequency-dependent effects of contact impedance on fdEIT in stroke detection in terms of the current distribution beneath the electrodes and the contact impedance imbalance between two measuring electrodes. The results showed that the contact impedance at high frequencies (>100 kHz) significantly changed the current distribution beneath the electrode, leading to nonnegligible errors in boundary voltages and artifacts in reconstructed images. The contact impedance imbalance at low frequencies (<1 kHz) also caused significant measurement errors. We conclude that the contact impedance has critical frequency-dependent influences on fdEIT and further studies on reducing such influences are necessary to improve the application of fdEIT in stroke detection.

The Frequency Spectral Properties of Electrode-Skin Contact Impedance on Human Head and Its Frequency-Dependent Effects on Frequency-Difference EIT in Stroke Detection from 10Hz to 1MHz

PubMed Central

Zhang, Ge; Li, Weichen; Fu, Feng; Shi, Xuetao; Dong, Xiuzhen

2017-01-01

Frequency-difference electrical impedance tomography (fdEIT) reconstructs frequency-dependent changes of a complex impedance distribution. It has a potential application in acute stroke detection because there are significant differences in impedance spectra between stroke lesions and normal brain tissues. However, fdEIT suffers from the influences of electrode-skin contact impedance since contact impedance varies greatly with frequency. When using fdEIT to detect stroke, it is critical to know the degree of measurement errors or image artifacts caused by contact impedance. To our knowledge, no study has systematically investigated the frequency spectral properties of electrode-skin contact impedance on human head and its frequency-dependent effects on fdEIT used in stroke detection within a wide frequency band (10 Hz-1 MHz). In this study, we first measured and analyzed the frequency spectral properties of electrode-skin contact impedance on 47 human subjects’ heads within 10 Hz-1 MHz. Then, we quantified the frequency-dependent effects of contact impedance on fdEIT in stroke detection in terms of the current distribution beneath the electrodes and the contact impedance imbalance between two measuring electrodes. The results showed that the contact impedance at high frequencies (>100 kHz) significantly changed the current distribution beneath the electrode, leading to nonnegligible errors in boundary voltages and artifacts in reconstructed images. The contact impedance imbalance at low frequencies (<1 kHz) also caused significant measurement errors. We conclude that the contact impedance has critical frequency-dependent influences on fdEIT and further studies on reducing such influences are necessary to improve the application of fdEIT in stroke detection. PMID:28107524

PROPERTIES OF PHANTOM TISSUE-LIKE POLYMETHYLPENTENE IN THE FREQUENCY RANGE 20–70 MHZ

PubMed Central

Madsen, Ernest L; Deaner, Meagan E; Mehi, James

2011-01-01

Quantitative ultrasound (QUS) has been employed to characterize soft tissues at ordinary abdominal ultrasound frequencies (2–15 MHz) and is beginning application at high frequencies (20–70 MHz). For example, backscatter and attenuation coefficients can be estimated in vivo using a reference phantom. At high frequencies it is crucial that reverberations do not compromise the measurements. Such reverberations can occur between the phantom's scanning window and transducer components as well as within the scanning window between its surfaces. Transducers are designed to minimize reverberations between the transducer and soft tissue. Thus, the acoustic impedance of a phantom scanning window should be tissue-like; polymethylpentene (TPX) is commonly used because of its tissue-like acoustic impedance. For QUS it is also crucial to correct for the transmission coefficient of the scanning window. Computation of the latter requires knowledge of the ultrasonic properties, viz, density, speed and attenuation coefficients. This work reports values for the ultrasonic properties of two versions of TPX over the high frequency range. One form (TPX film) is used as a scanning window on high frequency phantoms, and at 40 MHz and 22°C was found to have an attenuation coefficient of 120 dB/cm and a propagation speed of 2093 m/s. PMID:21723451

A low frequency RFI monitoring system

NASA Astrophysics Data System (ADS)

Amiri, Shahram; Shankar, N. Udaya; Girish, B. S.; Somashekar, R.

Radio frequency interference (RFI) is a growing problem for research in radio astronomy particularly at wavelengths longer than 2m. For satisfactory operation of a radio telescope, several bands have been protected for radio astronomy observations by the International Telecommunication Union. Since the radiation from cosmic sources are typically 40 to 100 dB below the emission from services operating in unprotected bands, often the out-of-band emission limits the sensitivity of astronomical observations. Moreover, several radio spectral emissions from cosmic sources are present in the frequency range outside the allocated band for radio astronomy. Thus monitoring of RFI is essential before building a receiver system for low frequency radio astronomy. We describe the design and development of an RFI monitoring system operating in the frequency band 30 to 100 MHz. This was designed keeping in view our proposal to extend the frequency of operation of GMRT down to 40 MHz. The monitor is a PC based spectrometer recording the voltage output of a receiver connected to an antenna, capable of digitizing the low frequency RF directly with an 8 bit ADC and sampling bandwidths up to 16 MHz. The system can operate continuously in almost real-time with a loss of only 2% of data. Here we will present the systems design aspects and the results of RFI monitoring carried out at the Raman Research Institute, Bangalore and at the GMRT site in Khodad.

Real-time ultrasound angiography using superharmonic dual-frequency (2.25MHz/30MHz) cylindrical array: In vitro study.

PubMed

Wang, Zhuochen; Martin, K Heath; Dayton, Paul A; Jiang, Xiaoning

2018-01-01

Recent studies suggest that dual-frequency intravascular ultrasound (IVUS) transducers allow detection of superharmonic bubble signatures, enabling acoustic angiography for microvascular and molecular imaging. In this paper, a dual-frequency IVUS cylindrical array transducer was developed for real-time superharmonic imaging. A reduced form-factor lateral mode transmitter (2.25MHz) was used to excite microbubbles effectively at 782kPa with single-cycle excitation while still maintaining the small size and low profile (5Fr) (3Fr=1mm) for intravascular imaging applications. Superharmonic microbubble responses generated in simulated microvessels were captured by the high frequency receiver (30MHz). The axial and lateral full-width half-maximum of microbubbles in a 200-μm-diameter cellulose tube were measured to be 162μm and 1039μm, respectively, with a contrast-to-noise ratio (CNR) of 16.6dB. Compared to our previously reported single-element IVUS transducers, this IVUS array design achieves a higher CNR (16.6dBvs 11dB) and improved axial resolution (162μmvs 616μm). The results show that this dual-frequency IVUS array transducer with a lateral-mode transmitter can fulfill the native design requirement (∼3-5Fr) for acoustic angiography by generating nonlinear microbubble responses as well as detecting their superharmonic responses in a 5Fr form factor. Copyright © 2017 Elsevier B.V. All rights reserved.

An Enhancing Effect of Gold Nanoparticles on the Lethal Action of 2450 MHz Electromagnetic Radiation in Microwave Oven

PubMed Central

Mollazadeh-Moghaddam, Kamyar; Moradi, Bardia Varasteh; Dolatabadi-Bazaz, Reza; Shakibae, Mojtaba; Shahverdi, Ahmad Reza

2011-01-01

Today, there is an increasing interest in the use of metal nanoparticles in health sciences. Amongst all nanoparticles, the gold nanoparticles have been known to kill the cancer cells under hyperthermic condition by near-infrared frequency electromagnetic waves. On the other hand, although there are different physiochemical methods for disinfection of microbial pollution, however applications of irradiated gold nanoparticles against microorganisms have not yet been investigated. In this study, gold nanoparticles were prepared using D-glucose and characterized (particle size <26 nm). In the next step, the enhancing effect of the non toxic level of gold nanoparticles (50 µg/mL) on the antimicrobial activity of 2450 MHz electromagnetic radiation generated at a microwave oven operated at low power (100 W), was investigated by time-kill course assay against Staphylococcus aureus (S.aureus) ATCC 29737. The results showed that application of gold nanoparticles can enhance the lethal effect of low power microwave in a very short exposure time (5 s). PMID:23407707

47 CFR 90.267 - Assignment and use of frequencies in the 450-470 MHz band for low power use.

Code of Federal Regulations, 2010 CFR

2010-10-01

...-470 MHz band for low power use. 90.267 Section 90.267 Telecommunication FEDERAL COMMUNICATIONS... Special Frequencies or Frequency Bands § 90.267 Assignment and use of frequencies in the 450-470 MHz band... medical radio telemetry device with an output power not to exceed 20 milliwatts without specific...

Thrombolysis using multi-frequency high intensity focused ultrasound at MHz range: an in vitro study

NASA Astrophysics Data System (ADS)

Suo, Dingjie; Guo, Sijia; Lin, Weili; Jiang, Xiaoning; Jing, Yun

2015-09-01

High intensity focused ultrasound (HIFU) based thrombolysis has emerged as a promising drug-free treatment approach for ischemic stroke. The large amount of acoustic power required by this approach, however, poses a critical challenge to the future clinical translation. In this study, multi-frequency acoustic waves at MHz range (near 1.5 MHz) were introduced as HIFU excitations to reduce the required power for treatment as well as the treatment time. In vitro bovine blood clots weighing around 150 mg were treated by single-frequency and multi-frequency HIFU. The pulse length was 2 ms for all experiments except the ones where the duty cycle was changed. It was found that dual-frequency thrombolysis efficiency was statistically better than single-frequency under the same acoustic power and excitation condition. When varying the acoustic power but fixing the duty cycle at 5%, it was found that dual-frequency ultrasound can save almost 30% power in order to achieve the same thrombolysis efficiency. In the experiment where the duty cycle was increased from 0.5% to 10%, it was shown that dual-frequency ultrasound can achieve the same thrombolysis efficiency with only half of the duty cycle of single-frequency. Dual-frequency ultrasound could also accelerate the thrombolysis by a factor of 2-4 as demonstrated in this study. No significant differences were found between dual-frequencies with different frequency differences (0.025, 0.05, and 0.1 MHz) and between dual-frequency and triple-frequency. The measured cavitation doses of dual-frequency and triple-frequency excitations were at about the same level but both were significantly higher than that of single-frequency.

47 CFR 15.243 - Operation in the band 890-940 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 890-940 MHz. 15.243 Section 15.243 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.243 Operation in the band 890-940...

47 CFR 15.241 - Operation in the band 174-216 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 174-216 MHz. 15.241 Section 15.241 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.241 Operation in the band 174-216...

Cavity ring-down spectroscopy of Doppler-broadened absorption line with sub-MHz absolute frequency accuracy.

PubMed

Cheng, C-F; Sun, Y R; Pan, H; Lu, Y; Li, X-F; Wang, J; Liu, A-W; Hu, S-M

2012-04-23

A continuous-wave cavity ring-down spectrometer has been built for precise determination of absolute frequencies of Doppler-broadened absorption lines. Using a thermo-stabilized Fabry-Pérot interferometer and Rb frequency references at the 780 nm and 795 nm, 0.1 - 0.6 MHz absolute frequency accuracy has been achieved in the 775-800 nm region. A water absorption line at 12579 cm(-1) is studied to test the performance of the spectrometer. The line position at zero-pressure limit is determined with an uncertainty of 0.3 MHz (relative accuracy of 0.8 × 10(-9)). © 2012 Optical Society of America

Long range ultra-high frequency (UHF) radio frequency identification (RFID) antenna design

NASA Astrophysics Data System (ADS)

Reynolds, Nathan D.

There is an ever-increasing demand for radio frequency identification (RFID) tags that are passive, long range, and mountable on multiple surfaces. Currently, RFID technology is utilized in numerous applications such as supply chain management, access control, and public transportation. With the combination of sensory systems in recent years, the applications of RFID technology have been extended beyond tracking and identifying. This extension includes applications such as environmental monitoring and healthcare applications. The available sensory systems usually operate in the medium or high frequency bands and have a low read range. However, the range limitations of these systems are being overcome by the development of RFID sensors focused on utilizing tags in the ultra-high frequency (UHF) band. Generally, RFID tags have to be mounted to the object that is being identified. Often the objects requiring identification are metallic. The inherent properties of metallic objects have substantial effects on nearby electromagnetic radiation; therefore, the operation of the tag antenna is affected when mounted on a metallic surface. This outlines one of the most challenging problems for RFID systems today: the optimization of tag antenna performance in a complex environment. In this research, a novel UHF RFID tag antenna, which has a low profile, long range, and is mountable on metallic surfaces, is designed analytically and simulated using a 3-D electromagnetic simulator, ANSYS HFSS. A microstrip patch antenna is selected as the antenna structure, as patch antennas are low profile and suitable for mounting on metallic surfaces. Matching and theoretical models of the microstrip patch antenna are investigated. Once matching and theory of a microstrip patch antenna is thoroughly understood, a unique design technique using electromagnetic band gap (EBG) structures is explored. This research shows that the utilization of an EBG structure in the patch antenna design yields

Real Space Imaging of the Microscopic Origins of the Ultrahigh Dielectric Constant in Polycrystalline CaCu 3Ti 4O 12

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

Kalinin, Sergei V; Shin, Junsoo; Veith, Gabriel M

2005-01-01

The origins of an ultrahigh dielectric constant in polycrystalline CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) were studied using the combination of impedance spectroscopy, electron microscopy, and scanning probe microscopy (SPM). Impedance spectra indicate that the transport properties in the 0.1 Hz-1 MHz frequency range are dominated by a single parallel resistive-capacitive (RC) element with a characteristic relaxation frequency of 16 Hz. dc potential distributions measurements by SPM illustrate that significant potential drops occur at the grain boundaries, which thus can be unambiguously identified as the dominant RC element. High frequency ac amplitude and phase distributions illustrate very weak grain boundary contrastmore » in SPM, indicative of strong capacitive coupling across the interfaces. These results demonstrate that the ultrahigh dielectric constant reported for polycrystalline CCTO materials is related to grain-boundary behavior.« less

Electromagnetic radiation at 900 MHz induces sperm apoptosis through bcl-2, bax and caspase-3 signaling pathways in rats.

PubMed

Liu, Qi; Si, Tianlei; Xu, Xiaoyun; Liang, Fuqiang; Wang, Lufeng; Pan, Siyi

2015-08-04

The decreased reproductive capacity of men is an important factor contributing to infertility. Accumulating evidence has shown that Electromagnetic radiation potentially has negative effects on human health. However, whether radio frequency electromagnetic radiation (RF-EMR) affects the human reproductive system still requires further investigation. Therefore, The present study investigates whether RF-EMR at a frequency of 900 MHz can trigger sperm cell apoptosis and affect semen morphology, concentration, and microstructure. Twenty four rats were exposed to 900 MHz electromagnetic radiation with a special absorption rate of 0.66 ± 0.01 W/kg for 2 h/d. After 50d, the sperm count, morphology, apoptosis, reactive oxygen species (ROS), and total antioxidant capacity (TAC), representing the sum of enzymatic and nonenzymatic antioxidants, were investigated. Western blotting and reverse transcriptase PCR were used to determine the expression levels of apoptosis-related proteins and genes, including bcl-2, bax, cytochrome c, and capase-3. In the present study, the percentage of apoptotic sperm cells in the exposure group was significantly increased by 91.42% compared with the control group. Moreover, the ROS concentration in exposure group was increased by 46.21%, while the TAC was decreased by 28.01%. Radiation also dramatically decreased the protein and mRNA expression of bcl-2 and increased that of bax, cytochrome c, and capase-3. RF-EMR increases the ROS level and decreases TAC in rat sperm. Excessive oxidative stress alters the expression levels of apoptosis-related genes and triggers sperm apoptosis through bcl-2, bax, cytochrome c and caspase-3 signaling pathways.

Polarization Observations of Giant Radio Pulses from the Millisecond Pulsar B1937+21 at a Frequency of 600 MHz

NASA Astrophysics Data System (ADS)

Popov, M. V.; Soglasnov, V. A.; Kondrat'ev, V. I.; Kostyuk, S. V.

2004-02-01

We performed polarization observations of giant radio pulses from the millisecond pulsar B1937+21. The observations were carried out in July 2002 with the 64-m Kalyazin radio telescope at a frequency of 600 MHz in two polarization channels with left- and right-hand circular polarizations (RCP and LCP). We used the S2 data acquisition system with a time resolution of 125 ns. The duration of an observing session was 20 min. We detected twelve giant radio pulses with peak flux densities higher than 1000 Jy; five and seven of these pulses appeared in the RCP and LCP channels, respectively. We found no event that exceeded the established detection threshold simultaneously in the two polarization channels. Thus, we may conclude that the detected giant pulses have a high degree of circular polarization, with the frequency of occurrence of RCP and LCP pulses being the same.

Measurement of high-degree solar oscillation frequencies

NASA Technical Reports Server (NTRS)

Bachmann, K. T.; Duvall, T. L., Jr.; Harvey, J. W.; Hill, F.

1995-01-01

We present m-averaged solar p- and f-mode oscillation frequencies over the frequency range nu greater than 1.8 and less than 5.0 mHz and the spherical harmonic degree range l greater than or equal to 100 and less than or equal to 1200 from full-disk, 1000 x 1024 pixel, Ca II intensity images collected 1993 June 22-25 with a temporal cadence of 60 s. We itemize the sources and magnitudes of statistical and systematic uncertainties and of small frequency corrections, and we show that our frequencies represent an improvement in accuracy and coverage over previous measurements. Our frequencies agree at the 2 micro Hz level with Mount Wilson frequencies determined for l less than or equal to 600 from full-disk images, and we find systematic offsets of 10-20 micro Hz with respect to frequencies measured from Big Bear and La Palma observations. We give evidence that these latter offsets are indicative of spatial scaling uncertainties associated with the analysis of partial-disk images. In comparison with theory, our p-mode frequencies agree within 10 micro Hz of frequencies predicted by the Los Alamos model but are as much as 100 micro Hz smaller than frequencies predicted by the Denmark and Yale models at degrees near 1000. We also find systematic differences between our n = 0 frequencies and the frequencies closely agreed upon by all three models.

Radiation cross-linking in ultra-high molecular weight polyethylene for orthopaedic applications

NASA Astrophysics Data System (ADS)

Oral, Ebru; Muratoglu, Orhun K.

2007-12-01

The motivation for radiation cross-linking of ultra-high molecular weight polyethylene (UHMWPE) is to increase its wear resistance to be used as bearing surfaces for total joint arthroplasty. However, radiation also leaves behind long-lived residual free radicals in this polymer, the reactions of which can detrimentally affect mechanical properties. In this review, we focus on the radiation cross-linking and oxidative stability of first and second generation highly cross-linked UHMWPEs developed in our laboratory.

Radio Frequency Electromagnetic Radiation From Streamer Collisions

NASA Astrophysics Data System (ADS)

Luque, Alejandro

2017-10-01

We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz. We also investigate the fast penetration, after a collision, of electromagnetic fields into the streamer heads and show that these fields are capable of accelerating electrons up to about 100 keV. By substantiating the link between X-rays and high-frequency radio emissions and by describing a mechanism for the early acceleration of runaway electrons, our results support the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges.

Radio Frequency Electromagnetic Radiation From Streamer Collisions.

PubMed

Luque, Alejandro

2017-10-16

We present a full electromagnetic model of streamer propagation where the Maxwell equations are solved self-consistently together with electron transport and reactions including photoionization. We apply this model to the collision of counter-propagating streamers in gaps tens of centimeters wide and with large potential differences of hundreds of kilovolts. Our results show that streamer collisions emit electromagnetic pulses that, at atmospheric pressure, dominate the radio frequency spectrum of an extended corona in the range from about 100 MHz to a few gigahertz. We also investigate the fast penetration, after a collision, of electromagnetic fields into the streamer heads and show that these fields are capable of accelerating electrons up to about 100 keV. By substantiating the link between X-rays and high-frequency radio emissions and by describing a mechanism for the early acceleration of runaway electrons, our results support the hypothesis that streamer collisions are essential precursors of high-energy processes in electric discharges.

Broadband pump-probe spectroscopy at 20-MHz modulation frequency.

PubMed

Preda, Fabrizio; Kumar, Vikas; Crisafi, Francesco; Figueroa Del Valle, Diana Gisell; Cerullo, Giulio; Polli, Dario

2016-07-01

We introduce an innovative high-sensitivity broadband pump-probe spectroscopy system, based on Fourier-transform detection, operating at 20-MHz modulation frequency. A common-mode interferometer employing birefringent wedges creates two phase-locked delayed replicas of the broadband probe pulse, interfering at a single photodetector. A single-channel lock-in amplifier demodulates the interferogram, whose Fourier transform provides the differential transmission spectrum. Our approach combines broad spectral coverage with high sensitivity, due to high-frequency modulation and detection. We demonstrate its performances by measuring two-dimensional differential transmission maps of a carbon nanotubes sample, simultaneously acquiring the signal over the entire 950-1350 nm range with 2.7·10^-6  rms noise over 1.5 s integration time.

47 CFR 15.223 - Operation in the band 1.705-10 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the band 1.705-10 MHz. 15.223 Section 15.223 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.223 Operation in the band 1.705-10...

Frequency agile microwave photonic notch filter with anomalously high stopband rejection.

PubMed

Marpaung, David; Morrison, Blair; Pant, Ravi; Eggleton, Benjamin J

2013-11-01

We report a novel class microwave photonic (MWP) notch filter with a very narrow isolation bandwidth (10 MHz), an ultrahigh stopband rejection (>60 dB), a wide frequency tuning (1-30 GHz), and flexible bandwidth reconfigurability (10-65 MHz). This performance is enabled by a new concept of sideband amplitude and phase controls using an electro-optic modulator and an optical filter. This concept enables energy efficient operation in active MWP notch filters, and opens up a pathway toward enabling low-power nanophotonic devices as high-performance RF filters.

Long term and excessive use of 900 MHz radiofrequency radiation alter microRNA expression in brain.

PubMed

Dasdag, Suleyman; Akdag, Mehmet Zulkuf; Erdal, Mehmet Emin; Erdal, Nurten; Ay, Ozlem Izci; Ay, Mustafa Ertan; Yilmaz, Senay Gorucu; Tasdelen, Bahar; Yegin, Korkut

2015-04-01

We still do not have any information on the interaction between radiofrequency radiation (RF) and miRNA, which play paramount role in growth, differentiation, proliferation and cell death by suppressing one or more target genes. The purpose of this study was to bridge this gap by investigating effects of long-term 900 MHz mobile phone exposure on some of the miRNA in brain tissue. The study was carried out on 14 Wistar Albino adult male rats by dividing them into two groups: Sham (n = 7) and exposure (n = 7). Rats in the exposure group were exposed to 900 MHz RF radiation for 3 h per day (7 days a week) for 12 months (one year). The same procedure was applied to the rats in the sham group except the generator was turned off. Immediately after the last exposure, rats were sacrificed and their brains were removed. rno-miR-9-5p, rno-miR-29a-3p, rno-miR-106b-5p, rno-miR-107 and rno-miR-125a-3p in brain were investigated in detail. Results revealed that long-term exposure of 900 MHz RF radiation only decreased rno-miR107 (adjP* = 0.045) value where the whole body (rms) SAR value was 0.0369 W/kg. However, our results indicated that other microRNA evaluated in this study was not altered by 900 MHz RF radiation. 900 MHz RF radiation can alter some of the miRNA, which, in turn, may lead to adverse effects. Therefore, further studies should be performed.

47 CFR 90.176 - Coordinator notification requirements on frequencies below 512 MHz, at 769-775/799-805 MHz, or at...

Code of Federal Regulations, 2014 CFR

2014-10-01

... Safety Pool, and subject to §§ 90.35(c)(13), (c)(25), or (d)(4) in the Industrial/Business Pool), all... Public Safety Pool and the Industrial/Business Pool. (c) Frequencies in the 769-775/799-805 MHz band... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND...

Optical injection locking-based amplification in phase-coherent transfer of optical frequencies.

PubMed

Kim, Joonyoung; Schnatz, Harald; Wu, David S; Marra, Giuseppe; Richardson, David J; Slavík, Radan

2015-09-15

We demonstrate the use of an optical injection phase locked loop (OIPLL) as a regenerative amplifier for optical frequency transfer applications. The optical injection locking provides high gain within a narrow bandwidth (<100  MHz) and is capable of preserving the fractional frequency stability of the incoming carrier to better than 10(-18) at 1000 s. The OIPLL was tested in the field as a mid-span amplifier for the transfer of an ultrastable optical carrier, stabilized to an optical frequency standard, over a 292 km long installed dark fiber link. The transferred frequency at the remote end reached a fractional frequency instability of less than 1×10(-19) at averaging time of 3200 s.

47 CFR 90.259 - Assignment and use of frequencies in the bands 216-220 MHz and 1427-1432 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... assignments will be made after January 1, 2002. (4) In the 217-220 MHz band, the maximum transmitter output... operations will not be authorized. The area of normal day-to-day operations will be described in the... will be assigned with a 6.25 kHz, 12.5 kHz, 25 kHz or 50 kHz channel bandwidth. Frequencies may be...

Energetic radiation influence on temperature dependency of Brillouin frequency in optical fibers

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

Pheron, X.; Ouerdane, Y.; Delepine-Lesoille, S.

We present a post mortem study of the influence of energetic radiation on optical fiber Brillouin sensors, both Brillouin spectrum and its temperature dependency in two different fibers, a photosensitive optical fiber and a SMF28. The target application is nuclear wastes repository monitoring where optical fiber Brillouin sensors might be exposed to energetic radiation. UV exposure induced optical losses, Brillouin frequency shifts up to 28 MHz and even a variation of the temperature dependency. The photosensitive optical fiber resulted more sensitive than SMF28{sup TM}. (authors)

Frequency-reconfigurable water antenna of circular polarization

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

Zou, Meng; Pan, Jin; Shen, Zhongxiang, E-mail: ezxshen@ntu.edu.sg

A circularly polarized frequency-reconfigurable water antenna with high radiation efficiency is proposed based on the design concept of combining a frequency-reconfigurable radiating structure with a frequency-independent feeding structure. In this letter, a resonator made of distilled water and an Archimedean spiral slot are employed as the radiating and feeding structures, respectively. The operating frequency of the antenna can be continuously tuned over a very wide range while maintaining good impendence matching and circular polarization by changing the dimensions of the water resonator. A prototype antenna is designed, fabricated, and measured. Simulated and measured results demonstrate that the designed antenna exhibitsmore » a wide tuning frequency range from 155 MHz to 400 MHz with an average radiation efficiency of about 90% and good circular polarization.« less

47 CFR 15.225 - Operation within the band 13.110-14.010 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation within the band 13.110-14.010 MHz. 15.225 Section 15.225 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.225 Operation within the band 13...

Square Kilometre Array Telescope—Precision Reference Frequency Synchronisation via 1f-2f Dissemination

PubMed Central

Wang, B.; Zhu, X.; Gao, C.; Bai, Y.; Dong, J. W.; Wang, L. J.

2015-01-01

The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, with a one-square-kilometre collecting area. In addition to its ambitious scientific objectives, such as probing cosmic dawn and the cradle of life, the SKA demands several revolutionary technological breakthroughs, such as ultra-high precision synchronisation of the frequency references for thousands of antennas. In this report, with the purpose of application to the SKA, we demonstrate a frequency reference dissemination and synchronisation scheme in which the phase-noise compensation function is applied at the client site. Hence, one central hub can be linked to a large number of client sites, thus forming a star-shaped topology. As a performance test, a 100-MHz reference frequency signal from a hydrogen maser (H-maser) clock is disseminated and recovered at two remote sites. The phase-noise characteristics of the recovered reference frequency signal coincide with those of the H-maser source and satisfy the SKA requirements. PMID:26349544

47 CFR 90.357 - Frequencies for LMS systems in the 902-928 MHz band.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 5 2010-10-01 2010-10-01 false Frequencies for LMS systems in the 902-928 MHz band. 90.357 Section 90.357 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.357 Frequencies for LMS systems in...

Analytical and numerical calculations of optimum design frequency for focused ultrasound therapy and acoustic radiation force.

PubMed

Ergün, A Sanlı

2011-10-01

Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well. Copyright © 2011 Elsevier B.V. All rights reserved.

47 CFR 15.229 - Operation within the band 40.66-40.70 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation within the band 40.66-40.70 MHz. 15.229 Section 15.229 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.229 Operation within the band 40.66...

47 CFR 15.227 - Operation within the band 26.96-27.28 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation within the band 26.96-27.28 MHz. 15.227 Section 15.227 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL RADIO FREQUENCY DEVICES Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.227 Operation within the band 26.96...

Direct link of a mid-infrared QCL to a frequency comb by optical injection.

PubMed

Borri, S; Galli, I; Cappelli, F; Bismuto, A; Bartalini, S; Cancio, P; Giusfredi, G; Mazzotti, D; Faist, J; De Natale, P

2012-03-15

A narrow-linewidth comb-linked nonlinear source is used as master radiation to injection lock a room-temperature mid-infrared quantum cascade laser (QCL). This process leads to a direct lock of the QCL to the optical frequency comb, providing the unique features of narrow linewidth, absolute frequency, higher output power, and wide mode-hop-free tunability. The QCL reproduces the injected radiation within more than 94%, with a reduction of the frequency-noise spectral density by 3 to 4 orders of magnitude up to about 100 kHz, and a linewidth narrowing from a few MHz to 20 kHz.

Initial report of the High Frequency Analyzer (HFA) onboard the ARASE (ERG) Satellite: Observations of the plasmasphere evolution and auroral kilometric radiation from the both hemisphere

NASA Astrophysics Data System (ADS)

Kumamoto, A.; Tsuchiya, F.; Kasahara, Y.; Kasaba, Y.; Kojima, H.; Yagitani, S.; Ishisaka, K.; Imachi, T.; Ozaki, M.; Matsuda, S.; Shoji, M.; Matsuoka, A.; Katoh, Y.; Miyoshi, Y.; Shinohara, I.; Obara, T.

2017-12-01

High Frequency Analyzer (HFA) is a subsystem of the Plasma Wave Experiment (PWE) onboard the ARASE (ERG, Exploration of energization and Radiation in Geospace) spacecraft for observation of radio and plasma waves in a frequency range from 0.01 to 10 MHz. In ARASE mission, HFA is expected to perform the following observations: (1) Upper hybrid resonance (UHR) waves in order to determine the electron number density around the spacecraft. (2) Magnetic field component of the chorus waves in a frequency range from 20 kHz to 100 kHz. (3) Radio and plasma waves excited via wave particle interactions and mode conversion processes in storm-time magnetosphere.HFA is operated in the following three observation modes: EE-mode, EB-mode, and PP-mode. In far-Earth region, HFA is operated in EE-mode. Spectrogram of two orthogonal or right and left-handed components of electric field in perpendicular directions to the spin axis of the spacecraft are obtained. In the near-Earth region, HFA is operated in EB-mode. Spectrogram of one components of electric field in perpendicular direction to the spin plane, and one component of the magnetic field in parallel direction to the spin axis are obtained. In EE and EB-modes, the frequency range from 0.01 to 10 MHz are covered with 480 frequency steps. The time resolution is 8 sec. We also prepared PP mode to measure the locations and structures of the plasmapause at higher resolution. In PP-mode, spectrogram of one electric field component in a frequency range from 0.01-0.4 MHz (PP1) or 0.1-1 MHz (PP2) can be obtained at time resolution of 1 sec.After the successful deployment of the wire antenna and search coils mast and initial checks, we could start routine observations and detect various radio and plasma wave phenomena such as upper hybrid resonance (UHR) waves, electrostatic electron cyclotron harmonic (ESCH) waves, auroral kilometric radiation (AKR), kilometric continuum (KC) and Type-III solar radio bursts. In the presentation, we

47 CFR 90.257 - Assignment and use of frequencies in the band 72-76 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... call box operations see § 90.241). (1) The following frequencies in the band 72-76 MHz may be used for fixed operations: MHz 72.02 72.80 72.04 72.82 72.06 72.84 72.08 72.86 72.10 72.88 72.12 72.90 72.14 72... any harmful interference caused by his operation to TV reception on either Channel 4 or 5 that might...

14 CFR Appendix J to Part 23 - HIRF Environments and Equipment HIRF Test Levels

Code of Federal Regulations, 2010 CFR

2010-01-01

... MHz. (4) From 100 MHz to 400 MHz, use radiated susceptibility tests at a minimum of 20 volts per meter... is specified in the following table: Table I.—HIRF Environment I Frequency Field strength(volts/meter) Peak Average 10 kHz-2 MHz 50 50 2 MHz-30 MHz 100 100 30 MHz-100 MHz 50 50 100 MHz-400 MHz 100 100 400...

Novel PMN-PT free standing film for high frequency (80MHz) intravascular ultrasonic imaging

PubMed Central

Li, Xiang; Zhou, Qifa; Shung, K. Kirk; Shih, Wei-Heng; Shih, Wan Y.

2011-01-01

[Pb(Mg1/3Nb2/3)O3]0.63[PbTiO3]0.37 (PMN-PT) free standing film of comparable piezoelectric property to bulk PMN-PT with a thickness of 33 μm has been fabricated using a modified precursor coating approach. At 1 KHz, the dielectric constant and loss were 4,160 and 0.0291, respectively. The remnant polarization and coercive field were 28 μC/cm2 and 18.43 kV/cm. The electromechanical coupling coefficient kt was measured to be 0.55, which was close to that of bulk PMN-PT single crystal material. A high frequency (80 MHz) miniature ultrasonic transducer with high sensitivity was fabricated from this film. In vitro imaging of a rabbit aorta was performed to demonstrate the application of this material to intravascular ultrasound imaging at 80 MHz. Compared to a 35 MHz ultrasonic image, the 80 MHz image showed superior resolution and contrast. PMID:22083761

High-Frequency (>50 MHz) Medical Ultrasound Linear Arrays Fabricated From Micromachined Bulk PZT Materials

PubMed Central

Liu, Changgeng; Zhou, Qifa; Djuth, Frank T.; Shung, K. Kirk

2012-01-01

This paper describes the development and characterization of a high-frequency (65-MHz) ultrasound transducer linear array. The array was built from bulk PZT which was etched using an optimized chlorine-based plasma dry-etching process. The median etch rate of 8 μm/h yielded a good profile (wall) angle (>83°) and a reasonable processing time for etch depths up to 40 μm (which corresponds to a 50-MHz transducer). A backing layer with an acoustic impedance of 6 MRayl and a front-end polymer matching layer yielded a transducer bandwidth of 40%. The major parameters of the transducer have been characterized. The two-way insertion loss and crosstalk between adjacent channels at the center frequency are 26.5 and −25 dB, respectively. PMID:24626041

Study on the electromagnetic radiation characteristics of discharging excimer laser system

NASA Astrophysics Data System (ADS)

Zhao, Duliang; Liang, Xu; Fang, Xiaodong; Wang, Qingsheng

2016-10-01

Excimer laser in condition of high voltage, large current and fast discharge will produce strong electromagnetic pulse radiation and electromagnetic interference on the around electrical equipment. The research on characteristics and distribution of excimer laser electromagnetic radiation could provide important basis for electromagnetic shielding and suppressing electromagnetic interference, and further improving the electromagnetic compatibility of system. Firstly, electromagnetic radiation source is analyzed according to the working principle of excimer laser. The key test points of the electromagnetic radiation, hydrogen thyratron, main discharge circuit and laser outlet, are determined by the mechanical structure and the theory of electromagnetic radiation. Secondly, characteristics of electromagnetic field were tested using a near field probe on the key positions of the vertical direction at 20, 50, and 80 cm, respectively. The main radiation frequencies and the radiation field characteristics in the near field are obtained. The experimental results show that the main radiation frequencies distribute in 47, 65, and 130 MHz for electric field and the main radiation frequencies distribute in 34, 100, and 165 MHz for magnetic field. The intensity of electromagnetic field decreases rapidly with the increase of test distance. The higher the frequency increases, the faster the amplitude attenuate. Finally, several electromagnetic interference suppression measurement methods are proposed from the perspective of electromagnetic compatibility according to the test results.

Airborne East Coast/Midwest urban survey at 121.5/243 MHz. [radio frequency interference measurement

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Hill, J. S.

1979-01-01

Results of an airborne RF interference measurement survey of the emergency-distress, Search and Rescue frequency bands at 121.5 and 243 MHz at an altitude of 25,000 ft over the U.S. East Coast and Midwest urban areas are presented. Included are a series of minutely median profile plots of antenna-noise temperature computed from RF interference power measurements at the output terminal of a quarter-wavelength monopole antenna, for both daytime and nighttime observations. The greatest value, 450,000 K, of minutely median temperature was recorded over New York City at 121.5 MHz during the day. East Coast urban areas exhibited a day-night effect at 121.5 MHz, where nighttime observations had a median value of 8.6-dB below daytime values; Midwest counterparts did not exhibit a significant day-night effect at 121.5 MHz.

Contactless microparticle control via ultrahigh frequency needle type single beam acoustic tweezers

NASA Astrophysics Data System (ADS)

Fei, Chunlong; Li, Ying; Zhu, Benpeng; Chiu, Chi Tat; Chen, Zeyu; Li, Di; Yang, Yintang; Kirk Shung, K.; Zhou, Qifa

2016-10-01

This paper reports on contactless microparticle manipulation including single-particle controlled trapping, transportation, and patterning via single beam acoustic radiation forces. As the core component of single beam acoustic tweezers, a needle type ultrasonic transducer was designed and fabricated with center frequency higher than 300 MHz and -6 dB fractional bandwidth as large as 64%. The transducer was built for an f-number close to 1.0, and the desired focal depth was achieved by press-focusing technology. Its lateral resolution was measured to be better than 6.7 μm by scanning a 4 μm tungsten wire target. Tightly focused acoustic beam produced by the transducer was shown to be capable of manipulating individual microspheres as small as 3 μm. "USC" patterning with 15 μm microspheres was demonstrated without affecting nearby microspheres. These promising results may expand the applications in biomedical and biophysical research of single beam acoustic tweezers.

Radiative instabilities and 1000 second fluctuations in astrophysical masers

NASA Technical Reports Server (NTRS)

Scappaticci, Gerardo A.; Watson, William D.

1992-01-01

A stability analysis for small (linear) perturbations is presented for the radiation in astrophysical masers treated in the usual, linear maser approximation. Instabilities that oscillate with a period of about L/c, where L is the length of the maser are found. They occur (1) when the maser is partly but not heavily saturated, (2) when the decay rate Gamma for the molecular states is near c/L, and (3) when the product of the brightness temperature T sub 0 of the incident radiation and the angle for the beaming is less than a critical value that depends upon the particular masing transition. A fourth parameter, the fractional inversion in the pumping multiplied by (T sub 0/frequency), determines the importance of spontaneous emission which can eliminate the instabilities. These instabilities are a likely cause for the fluctuations in the radiation from the 18 cm OH masers that have been reported to occur on time scales as short as 1000 s. The calculations are applicable to other types of astrophysical masers as well, and suggest that spontaneous emission will prevent similar instabilities in the H2O and SiO masers.

14 CFR Appendix L to Part 25 - HIRF Environments and Equipment HIRF Test Levels

Code of Federal Regulations, 2010 CFR

2010-01-01

... 400 MHz, use radiated susceptibility tests at a minimum of 20 volts per meter (V/m) peak with CW and 1... table: Table I.—HIRF Environment I Frequency Field strength(volts/meter) Peak Average 10 kHz-2 MHz 50 50 2 MHz-30 MHz 100 100 30 MHz-100 MHz 50 50 100 MHz-400 MHz 100 100 400 MHz-700 MHz 700 50 700 MHz-1...

Calibration of laser vibrometers at frequencies up to 100 kHz and higher

NASA Astrophysics Data System (ADS)

Silva Pineda, Guillermo; von Martens, Hans-Jürgen; Rojas, Sergio; Ruiz, Arturo; Muñiz, Lorenzo

2008-06-01

Manufacturers and users of laser vibrometers exploit the wide frequency and intensity ranges of laser techniques, ranging over many decades (e.g., from 0.1 Hz to 100 MHz). Traceability to primary measurement standards is demanded over the specified measurement ranges of any measurement instrumentation. As the primary documentary standard ISO 16063-11 for the calibration of vibration transducers is restricted to 10 kHz, a new international standard for the calibration of laser vibrometers, ISO 16063-41, is under development. The current stage of the 2nd Committee Draft (CD) of the ISO standard specifies calibration methods for frequencies from 0.4 Hz to 50 kHz which does not meet the demand for providing traceability at higher frequencies. New investigations will be presented which demonstrate the applicability of the laser interferometer methods specified in ISO 16063-11 and in the 2nd CD also at higher frequencies of 100 kHz and beyond. The three standard methods were simultaneously used for vibration displacement and acceleration measurements up to 100 kHz, and a fourth high-accuracy method has been developed and used. Their results in displacement and acceleration measurements deviated by less than 1 % from each other at vibration displacement amplitudes in the order of 100 nm. In addition to the three interferometer methods specified in ISO 16063-11 and 16063-15, and in the 2nd Committee Draft of 16063-41 as well, measurement results will be presented. Examples of laser vibrometer calibrations will bedemonstrated. Further investigations are aimed

Ultrahigh resolution radiation imaging system using an optical fiber structure scintillator plate.

PubMed

Yamamoto, Seiichi; Kamada, Kei; Yoshikawa, Akira

2018-02-16

High resolution imaging of radiation is required for such radioisotope distribution measurements as alpha particle detection in nuclear facilities or high energy physics experiments. For this purpose, we developed an ultrahigh resolution radiation imaging system using an optical fiber structure scintillator plate. We used a ~1-μm diameter fiber structured GdAlO 3 :Ce (GAP) /α-Al 2 O 3 scintillator plate to reduce the light spread. The fiber structured scintillator plate was optically coupled to a tapered optical fiber plate to magnify the image and combined with a lens-based high sensitivity CCD camera. We observed the images of alpha particles with a spatial resolution of ~25 μm. For the beta particles, the images had various shapes, and the trajectories of the electrons were clearly observed in the images. For the gamma photons, the images also had various shapes, and the trajectories of the secondary electrons were observed in some of the images. These results show that combining an optical fiber structure scintillator plate with a tapered optical fiber plate and a high sensitivity CCD camera achieved ultrahigh resolution and is a promising method to observe the images of the interactions of radiation in a scintillator.

Challenges and regulatory considerations in the acoustic measurement of high-frequency (>20 MHz) ultrasound.

PubMed

Nagle, Samuel M; Sundar, Guru; Schafer, Mark E; Harris, Gerald R; Vaezy, Shahram; Gessert, James M; Howard, Samuel M; Moore, Mary K; Eaton, Richard M

2013-11-01

This article examines the challenges associated with making acoustic output measurements at high ultrasound frequencies (>20 MHz) in the context of regulatory considerations contained in the US Food and Drug Administration industry guidance document for diagnostic ultrasound devices. Error sources in the acoustic measurement, including hydrophone calibration and spatial averaging, nonlinear distortion, and mechanical alignment, are evaluated, and the limitations of currently available acoustic measurement instruments are discussed. An uncertainty analysis of acoustic intensity and power measurements is presented, and an example uncertainty calculation is done on a hypothetical 30-MHz high-frequency ultrasound system. This analysis concludes that the estimated measurement uncertainty of the acoustic intensity is +73%/-86%, and the uncertainty in the mechanical index is +37%/-43%. These values exceed the respective levels in the Food and Drug Administration guidance document of 30% and 15%, respectively, which are more representative of the measurement uncertainty associated with characterizing lower-frequency ultrasound systems. Recommendations made for minimizing the measurement uncertainty include implementing a mechanical positioning system that has sufficient repeatability and precision, reconstructing the time-pressure waveform via deconvolution using the hydrophone frequency response, and correcting for hydrophone spatial averaging.

Long term exposure to cell phone frequencies (900 and 1800 MHz) induces apoptosis, mitochondrial oxidative stress and TRPV1 channel activation in the hippocampus and dorsal root ganglion of rats.

PubMed

Ertilav, Kemal; Uslusoy, Fuat; Ataizi, Serdar; Nazıroğlu, Mustafa

2018-06-01

Mobile phone providers use electromagnetic radiation (EMR) with frequencies ranging from 900 to 1800 MHz. The increasing use of mobile phones has been accompanied by several potentially pathological consequences, such as neurological diseases related to hippocampal (HIPPON) and dorsal root ganglion neuron (DRGN). The TRPV1 channel is activated different stimuli, including CapN, high temperature and oxidative stress. We investigated the contribution TRPV1 to mitochondrial oxidative stress and apoptosis in HIPPON and DRGN following long term exposure to 900 and 1800 MHz in a rat model. Twenty-four adult rats were equally divided into the following groups: (1) control, (2) 900 MHz, and (3) 1800 MHz exposure. Each experimental group was exposed to EMR for 60 min/ 5 days of the week during the one year. The 900 and 1800 MHz EMR exposure induced increases in TRPV1 currents, intracellular free calcium influx (Ca 2+ ), reactive oxygen species (ROS) production, mitochondrial membrane depolarization (JC-1), apoptosis, and caspase 3 and 9 activities in the HIPPON and DRGN. These deleterious processes were further increased in the 1800 MHz experimental group compared to the 900 MHz exposure group. In conclusion, mitochondrial oxidative stress, programmed cell death and Ca 2+ entry pathway through TRPV1 activation in the HIPPON and DRGN of rats were increased in the rat model following exposure to 900 and 1800 MHz cell frequencies. Our results suggest that exposure to 900 and 1800 MHz EMR may induce a dose-associated, TRPV1-mediated stress response.

Detection of Ultrahigh-Energy Cosmic Rays with the Auger Engineering Radio Array

NASA Astrophysics Data System (ADS)

Krause, Raphael; Pierre Auger Collaboration

2017-02-01

Ultrahigh-energy cosmic rays interact with the Earth's atmosphere and produce great numbers of secondary particles forming an extensive air shower. These air showers emit radiation in the radio frequency range which delivers important information about the processes of radio emission in extensive air showers and properties of the primary cosmic rays, e.g. arrival direction, energy and mass with a duty cycle close to 100%. The radio extension of the world's largest cosmic-ray experiment, the Pierre Auger Observatory, is called the Auger Engineering Radio Array (AERA). In addition to the particle and fluorescence detectors of the Pierre Auger Observatory, AERA investigates the electromagnetic component of extensive air showers using 153 autonomous radio stations on an area of 17km2 .

Micro-machined high-frequency (80 MHz) PZT thick film linear arrays.

PubMed

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K

2010-10-01

This paper presents the development of a micromachined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT sol-gel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (-6 dB) of 60%. An insertion loss of -41 dB and adjacent element crosstalk of -21 dB were found at the center frequency.

Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

NASA Astrophysics Data System (ADS)

Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

2016-09-01

Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

AlGaN/GaN-HEMTs with a breakdown voltage higher than 100 V and maximum oscillation frequency f{sub max} as high as 100 GHz

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

Mokerov, V. G., E-mail: vgmokerov@yandex.ru; Kuznetsov, A. L.; Fedorov, Yu. V.

2009-04-15

The N-Al{sub 0.27}Ga{sub 0.73}N/GaN High Electron Mobility Transistors (HEMTs) with different gate lengths L{sub g} (ranging from 170 nm to 0.5 {mu}m) and gate widths W{sub s} (ranging from 100 to 1200 {mu}m) have been studied. The S parameters have been measured; these parameters have been used to determine the current-gain cutoff frequency f{sub t}, the maximum oscillation frequency f{sub max}, and the power gain MSG/MAG and Mason's coefficients were investigated in the frequency range from 10 MHz to 67 GHz in relation to the gate length and gate width. It was found that the frequencies f{sub t} and f{submore » max} attain their maximum values of f{sub t} = 48 GHz and f{sub max} = 100 GHz at L{sub g} = 170 nm and W{sub g} = 100 {mu}m. The optimum values of W{sub g} and output power P out of the basic transistors have been determined for different frequencies of operation. It has also been demonstrated that the 170 nm Al{sub 0.27}Ga{sub 0.73}N/GaN HEMT technology provides both good frequency characteristics and high breakdown voltages and is very promising for high-frequency applications (up to 40 GHz)« less

[Blocking 1800 MHz mobile phone radiation-induced reactive oxygen species production and DNA damage in lens epithelial cells by noise magnetic fields].

PubMed

Wu, Wei; Yao, Ke; Wang, Kai-jun; Lu, De-qiang; He, Ji-liang; Xu, Li-hong; Sun, Wen-jun

2008-01-01

To investigate whether the exposure to the electromagnetic noise can block reactive oxygen species (ROS) production and DNA damage of lens epithelial cells induced by 1800 MHz mobile phone radiation. The DCFH-DA method and comet assay were used respectively to detect the intracellular ROS and DNA damage of cultured human lens epithelial cells induced by 4 W/kg 1800 MHz mobile phone radiation or/and 2 muT electromagnetic noise for 24 h intermittently. 1800 MHz mobile phone radiation at 4 W/kg for 24 h increased intracellular ROS and DNA damage significantly (P<0.05). However, the ROS level and DNA damage of mobile phone radiation plus noise group were not significant enhanced (P>0.05) as compared to sham exposure group. Electromagnetic noise can block intracellular ROS production and DNA damage of human lens epithelial cells induced by 1800 MHz mobile phone radiation.

The effect of 1800MHz radio-frequency radiation on NMDA receptor subunit NR1 expression and peroxidation in the rat brain in healthy and inflammatory states.

PubMed

Bodera, Paweł; Makarova, Katerina; Zawada, Katarzyna; Antkowiak, Bożena; Paluch, Małgorzata; Sobiczewska, Elżbieta; Sirav, Bahriye; Siwicki, Andrzej K; Stankiewicz, Wanda

2017-08-01

The aim of this study was to evaluate the effect of repeated exposure (5 times for 15min) of 1800MHz radio-frequency radiation (RFR) on N-methyl-d-aspartate receptor subunit NR1 (NMDA-NR1) expression in the brains of rats in a persistent inflammatory state. We also measured the effect of RFR combined with tramadol (TRAM) to determine the potential antioxidant capacity of this agent. The effects of the Global System for Mobile Communication (GSM) modulated 1800MHz RFR exposure on the expression and activity of glutamate receptor channels with antioxidative activity in brain tissue was measured using oxygen radical absorbance capacity (ORAC) and electron spin resonance (ESR) detection of the hydroxyl radical generated by the Fenton reaction. NMDA-NR1 was measured in the cerebral tissue of rats with inflammation (complete Freund's adjuvent) and those injected with tramadol after RFR exposure (RFR, RFR/TRAM) and in non-exposed (baseline, TRAM) rats. No differences between the baseline group and the exposed group (RFR) were observed. NMDA-NR1 expression decreased after CFA injection and RFR exposure, and an elevated expression of NMDA-NR1 was observed in healthy control rats of both groups: TRAM/RFR and RFR. ORAC assessment revealed a robust effect of RFR, however the other experiments revealed equivocal effects. Further studies examining the combination of ORAC with NMDA are warranted to elucidate more clearly the effect of RFR on the brain. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Evaluation of 220 MHz frequencies for ITS experimentation

DOT National Transportation Integrated Search

2002-02-01

The Kentucky Transportation Cabinet implemented a 220 MHz wireless communication system as part of the TRIMARC traffic management system. The purpose of this research effort was to evaluate the use of the 220 MHz system to transmit data collected at ...

47 CFR 15.109 - Radiated emission limits.

Code of Federal Regulations, 2011 CFR

2011-10-01

... of 9 kHz to 30 MHz, including devices that deliver the radio frequency energy to transducers, such as... for intentional radiators provided in § 15.209 for the frequency range of 9 kHz to 30 MHz. As an... 525 kHz to 1705 kHz may comply with the radiated emission limits provided in § 15.221(a). At...

47 CFR 15.109 - Radiated emission limits.

Code of Federal Regulations, 2014 CFR

2014-10-01

... of 9 kHz to 30 MHz, including devices that deliver the radio frequency energy to transducers, such as... for intentional radiators provided in § 15.209 for the frequency range of 9 kHz to 30 MHz. As an... 525 kHz to 1705 kHz may comply with the radiated emission limits provided in § 15.221(a). At...

47 CFR 15.109 - Radiated emission limits.

Code of Federal Regulations, 2013 CFR

2013-10-01

... of 9 kHz to 30 MHz, including devices that deliver the radio frequency energy to transducers, such as... for intentional radiators provided in § 15.209 for the frequency range of 9 kHz to 30 MHz. As an... 525 kHz to 1705 kHz may comply with the radiated emission limits provided in § 15.221(a). At...

47 CFR 15.109 - Radiated emission limits.

Code of Federal Regulations, 2012 CFR

2012-10-01

... of 9 kHz to 30 MHz, including devices that deliver the radio frequency energy to transducers, such as... for intentional radiators provided in § 15.209 for the frequency range of 9 kHz to 30 MHz. As an... 525 kHz to 1705 kHz may comply with the radiated emission limits provided in § 15.221(a). At...

Encapsulated high frequency (235 kHz), high-Q (100 k) disk resonator gyroscope with electrostatic parametric pump

NASA Astrophysics Data System (ADS)

Ahn, C. H.; Nitzan, S.; Ng, E. J.; Hong, V. A.; Yang, Y.; Kimbrell, T.; Horsley, D. A.; Kenny, T. W.

2014-12-01

In this paper, we explore the effects of electrostatic parametric amplification on a high quality factor (Q > 100 000) encapsulated disk resonator gyroscope (DRG), fabricated in <100> silicon. The DRG was operated in the n = 2 degenerate wineglass mode at 235 kHz, and electrostatically tuned so that the frequency split between the two degenerate modes was less than 100 mHz. A parametric pump at twice the resonant frequency is applied to the sense axis of the DRG, resulting in a maximum scale factor of 156.6 μV/(°/s), an 8.8× improvement over the non-amplified performance. When operated with a parametric gain of 5.4, a minimum angle random walk of 0.034°/√h and bias instability of 1.15°/h are achieved, representing an improvement by a factor of 4.3× and 1.5×, respectively.

Wireless, Room Temperature Volatile Organic Compound Sensor Based on Polypyrrole Nanoparticle Immobilized Ultrahigh Frequency Radio Frequency Identification Tag.

PubMed

Jun, Jaemoon; Oh, Jungkyun; Shin, Dong Hoon; Kim, Sung Gun; Lee, Jun Seop; Kim, Wooyoung; Jang, Jyongsik

2016-12-07

Due to rapid advances in technology which have contributed to the development of portable equipment, highly sensitive and selective sensor technology is in demand. In particular, many approaches to the modification of wireless sensor systems have been studied. Wireless systems have many advantages, including unobtrusive installation, high nodal densities, low cost, and potential commercial applications. In this study, we fabricated radio frequency identification (RFID)-based wireless sensor systems using carboxyl group functionalized polypyrrole (C-PPy) nanoparticles (NPs). The C-PPy NPs were synthesized via chemical oxidation copolymerization, and then their electrical and chemical properties were characterized by a variety of methods. The sensor system was composed of an RFID reader antenna and a sensor tag made from a commercially available ultrahigh frequency RFID tag coated with C-PPy NPs. The C-PPy NPs were covalently bonded to the tag to form a passive sensor. This type of sensor can be produced at a very low cost and exhibits ultrahigh sensitivity to ammonia, detecting concentrations as low as 0.1 ppm. These sensors operated wirelessly and maintained their sensing performance as they were deformed by bending and twisting. Due to their flexibility, these sensors may be used in wearable technologies for sensing gases.

Micro-Machined High-Frequency (80 MHz) PZT Thick Film Linear Arrays

PubMed Central

Zhou, Qifa; Wu, Dawei; Liu, Changgeng; Zhu, Benpeng; Djuth, Frank; Shung, K. Kirk

2010-01-01

This paper presents the development of a micro-machined high-frequency linear array using PZT piezoelectric thick films. The linear array has 32 elements with an element width of 24 μm and an element length of 4 mm. Array elements were fabricated by deep reactive ion etching of PZT thick films, which were prepared from spin-coating of PZT solgel composite. Detailed fabrication processes, especially PZT thick film etching conditions and a novel transferring-and-etching method, are presented and discussed. Array designs were evaluated by simulation. Experimental measurements show that the array had a center frequency of 80 MHz and a fractional bandwidth (−6 dB) of 60%. An insertion loss of −41 dB and adjacent element crosstalk of −21 dB were found at the center frequency. PMID:20889407

Proposed Ultra-High Sensitivity High-Frequency Gravitational Wave Detector

NASA Astrophysics Data System (ADS)

Baker, Robert M. L.; Stephenson, Gary V.; Li, Fangyu

2008-01-01

The paper discusses the proposed improvement of a High-Frequency Relic Gravitational Wave (HFRGW) detector designed by Li, Baker, Fang, Stephenson and Chen in order to greatly improve its sensitivity. The improved detector is inspired by the Laser Interferometer Gravitational Observatory or LIGO, but is sensitive to the high-frequency end of the gravitational-wave spectrum. As described in prior papers it utilizes the Gertsenshtein effect, which introduces the conversion of gravitational waves to electromagnetic (EM) waves in the presence of a static magnetic field. Such a conversion, if it leads to photons moving in a direction perpendicular to the plane of the EM waves and the magnetic field, will allow for ultra-high sensitivity HFRGW detection. The use of sensitive microwave, single photon detectors such as a circuit QED and/or the Rydberg Atom Cavity Detector, or off-the-shelf detectors, could lead to such detection. When the EM-detection photons are focused at the microwave detectors by fractal-membrane reflectors sensitivity is also improved. Noise sources external to the HFRGW detector will be eliminated by placing a tight mosaic of superconducting tiles (e.g., YBCO) and/or fractal membranes on the interior surface of the detector's cryogenic containment vessel in order to provide a perfect Faraday cage. Internal thermal noise will be eliminated by means of a microwave absorbing (or reflecting) interior enclosure shaped to conform to a high-intensity continuous microwave Gaussian beam (GB), will reduce any background photon flux (BPF) noise radiated normal to the GB's axis. Such BPF will be further attenuated by a series of microwave absorbing baffles forming tunnels to the sensitive microwave detectors on each side of the GB and at right angles to the static magnetic field. A HFGW detector of bandwidth of 1 KHz to 10 KHz or less in the GHz band has been selected. It is concluded that the utilization of the new ultra-high-sensitivity microwave detectors

Low-Frequency Carbon Recombination Lines in the Orion Molecular Cloud Complex

NASA Astrophysics Data System (ADS)

Tremblay, Chenoa D.; Jordan, Christopher H.; Cunningham, Maria; Jones, Paul A.; Hurley-Walker, Natasha

2018-05-01

We detail tentative detections of low-frequency carbon radio recombination lines from within the Orion molecular cloud complex observed at 99-129 MHz. These tentative detections include one alpha transition and one beta transition over three locations and are located within the diffuse regions of dust observed in the infrared at 100 μm, the Hα emission detected in the optical, and the synchrotron radiation observed in the radio. With these observations, we are able to study the radiation mechanism transition from collisionally pumped to radiatively pumped within the H ii regions within the Orion molecular cloud complex.

The TexOx-1000 redshift survey of radio sources I: the TOOT00 region

NASA Astrophysics Data System (ADS)

Vardoulaki, Eleni; Rawlings, Steve; Hill, Gary J.; Mauch, Tom; Inskip, Katherine J.; Riley, Julia; Brand, Kate; Croft, Steve; Willott, Chris J.

2010-01-01

We present optical spectroscopy, near-infrared (mostly K-band) and radio (151-MHz and 1.4-GHz) imaging of the first complete region (TOOT00) of the TexOx-1000 (TOOT) redshift survey of radio sources. The 0.0015-sr (~5 deg2) TOOT00 region is selected from pointed observations of the Cambridge Low-Frequency Survey Telescope at 151 MHz at a flux density limit of ~=100 mJy, approximately five times fainter than the 7C Redshift Survey (7CRS), and contains 47 radio sources. We have obtained 40 spectroscopic redshifts (~85 per cent completeness). Adding redshifts estimated for the seven other cases yields a median redshift zmed ~ 1.25. We find a significant population of objects with Fanaroff-Riley type I (FRI) like radio structures at radio luminosities above both the low-redshift FRI/II break and the break in the radio luminosity function. The redshift distribution and subpopulations of TOOT00 are broadly consistent with extrapolations from the 7CRS/6CE/3CRR data sets underlying the SKADS Simulated Skies Semi-Empirical Extragalactic Data base, S3-SEX.

1.55-μm mode-locked quantum-dot lasers with 300 MHz frequency tuning range

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

Sadeev, T., E-mail: tagir@mailbox.tu-berlin.de; Arsenijević, D.; Bimberg, D.

2015-01-19

Passive mode-locking of two-section quantum-dot mode-locked lasers grown by metalorganic vapor phase epitaxy on InP is reported. 1250-μm long lasers exhibit a wide tuning range of 300 MHz around the fundamental mode-locking frequency of 33.48 GHz. The frequency tuning is achieved by varying the reverse bias of the saturable absorber from 0 to −2.2 V and the gain section current from 90 to 280 mA. 3 dB optical spectra width of 6–7 nm leads to ex-facet optical pulses with full-width half-maximum down to 3.7 ps. Single-section quantum-dot mode-locked lasers show 0.8 ps broad optical pulses after external fiber-based compression. Injection current tuning from 70 tomore » 300 mA leads to 30 MHz frequency tuning.« less

Fully automated 1.5 MHz FDML laser with more than 100mW output power at 1310 nm

NASA Astrophysics Data System (ADS)

Wieser, Wolfgang; Klein, Thomas; Draxinger, Wolfgang; Huber, Robert

2015-07-01

While FDML lasers with MHz sweep speeds have been presented five years ago, these devices have required manual control for startup and operation. Here, we present a fully self-starting and continuously regulated FDML laser with a sweep rate of 1.5 MHz. The laser operates over a sweep range of 115 nm centered at 1315 nm, and provides very high average output power of more than 100 mW. We characterize the laser performance, roll-off, coherence length and investigate the wavelength and phase stability of the laser output under changing environmental conditions. The high output power allows optical coherence tomography (OCT) imaging with an OCT sensitivity of 108 dB at 1.5 MHz.

The effect of radio frequency interference on the 136- to 138-MHz return link and 400.5- to 401.5-MHz forward link of the Tracking and Data Relay Satellite System

NASA Technical Reports Server (NTRS)

Jenny, J.; Lyttle, J. D.

1973-01-01

The purpose is to update the RFI estimates in the 136- to 138-MHz VHF band and to make estimates for the first time for the 400.5- to 401.5-MHz UHF band. These preliminary predictions are based on primarily ITU frequency-registration data, with missing data bridged by engineering judgement.

Experimental investigations of driving frequency effect in low-pressure capacitively coupled oxygen discharges

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

Liu, Jia; Liu, Yong-Xin; Liu, Gang-Hu

2015-04-14

The effect of driving frequency on the electron density is investigated in low-pressure capacitively coupled oxygen plasmas by utilizing a floating hairpin probe. The power absorbed by the plasma is investigated and it is found that the power lost in the matching network can reach 50% or higher under certain conditions. The effect of driving frequency on the electron density is studied from two aspects, i.e., constant absorbed power and electrode voltage. In the former case, the electron density increases with the driving frequency increasing from 13.56 to 40.68 MHz and slightly changes depending on the gas pressures with the frequencymore » further increasing to 100 MHz. In the latter case, the electron density rapidly increases when the driving frequency increases from 13.56 to 40.68 MHz, and then decreases with the frequency further increasing to 100 MHz. The electron series resonance is observed at 40.68 MHz and can be attributed to the higher electron density. And the standing wave effect also plays an important role in increasing electron density at 100 MHz and 2.6 Pa.« less

A 30-MHz piezo-composite ultrasound array for medical imaging applications.

PubMed

Ritter, Timothy A; Shrout, Thomas R; Tutwiler, Rick; Shung, K Kirk

2002-02-01

Ultrasound imaging at frequencies above 20 MHz is capable of achieving improved resolution in clinical applications requiring limited penetration depth. High frequency arrays that allow real-time imaging are desired for these applications but are not yet currently available. In this work, a method for fabricating fine-scale 2-2 composites suitable for 30-MHz linear array transducers was successfully demonstrated. High thickness coupling, low mechanical loss, and moderate electrical loss were achieved. This piezo-composite was incorporated into a 30-MHz array that included acoustic matching, an elevation focusing lens, electrical matching, and an air-filled kerf between elements. Bandwidths near 60%, 15-dB insertion loss, and crosstalk less than -30 dB were measured. Images of both a phantom and an ex vivo human eye were acquired using a synthetic aperture reconstruction method, resulting in measured lateral and axial resolutions of approximately 100 microm.

BIOLOGICAL EFFECTS OF LONG-TERM EXPOSURE OF RATS TO 970-MHZ RADIOFREQUENCY RADIATION

EPA Science Inventory

Rats (N=16) exposed individually in circularly polarized waveguides to 970-MHz electromagnetic radiation (SAR=2.5 mW/g, 22 h daily for 70 consecutive days) had significantly higher serum levels of triglycerides, albumin, and total protein compared with sham-irradiated controls. N...

Unknown radio emission at about 3 MHz recorded in Norway

NASA Astrophysics Data System (ADS)

Farges, T.; Blanc, E.; Strand, E.

2012-04-01

A wideband electric field antenna has been installed in Norway (at Hessdalen, 62°41' North and 11°12' East). A signal of 50 ms is automatically recorded every 5 s in order to monitor the spectral variations from 1 kHz to 5 MHz. Signals have been acquired during more than one year from September 2010 to December 2011. The measured electromagnetic spectrum is very similar to other spectra commonly measured in other places in the World. It shows emissions in numerous bands at fixed frequencies corresponding to radio transmissions in VLF, LF, MF and HF bands. However, one emission is quite different and arouses our curiosity. We find a quasi-continuous radio emission at a frequency varying from 2.7 to more than 3.4 MHz with a mean value of 3.0 MHz. The bandwidth is quite large (about 40 kHz) while it is about 9 kHz for all the other radio emissions at frequencies higher than 100 kHz. During the night, the frequency is relatively stable at about 3.1 MHz while during day-time a frequency shift of 200-300 kHz is often observed. These variations can be quick (few tens of minutes) or slow (several hours). Moreover, the emission disappears during day-time, the disappearance duration depending on the daylight duration. From November to the end of March, there is almost no disappearance while in April disappearances are more frequent and longer. From May to July, the emission disappears systematically during day-time from 6:00 UT to 20:00 UT. At the sunrise time the emission frequency suddenly decreases and systematically disappears when it reaches a threshold value (from 2.7 to 2.85 MHz). The emission (frequency and duration) is not influenced by the magnetic storms. We will show in the paper statistical results and some hypothesis on the mechanism which can produce this radio emission.

SU-F-J-45: Sparing Normal Tissue with Ultra-High Dose Rate in Radiation Therapy

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

Feng, Y

Purpose: To spare normal tissue by reducing the location uncertainty of a moving target, we proposed an ultra-high dose rate system and evaluated. Methods: High energy electrons generated with a linear accelerator were injected into a storage ring to be accumulated. The number of the electrons in the ring was determined based on the prescribed radiation dose. The dose was delivered within a millisecond, when an online imaging system found that the target was in the position that was consistent with that in a treatment plan. In such a short time period, the displacement of the target was negligible. Themore » margin added to the clinical target volume (CTV) could be reduced that was evaluated by comparing of volumes between CTV and ITV in 14 cases of lung stereotactic body radiation therapy (SBRT) treatments. A design of the ultra-high dose rate system was evaluated based clinical needs and the recent developments of low energy (a few MeV) electron storage ring. Results: This design of ultra-high dose rate system was feasible based on the techniques currently available. The reduction of a target volume was significant by reducing the margin that accounted the motion of the target. ∼50% volume reduction of the internal target volume (ITV) could be achieved in lung SBRT treatments. Conclusion: With this innovation of ultra-high dose rate system, the margin of target is able to be significantly reduced. It will reduce treatment time of gating and allow precisely specified gating window to improve the accuracy of dose delivering.« less

ANDalyze Lead 100 Test Kit and AND1000 Fluorimeter Environmental Technology Verification Report and Statement

EPA Science Inventory

This report provides results for the verification testing of the Lead100/AND1000. The following is a description of the technology based on information provided by the vendor. The information provided below was not verified in this test. The ANDalyze Lead100/AND1000 was des...

Salt Neutrino Detector for Ultrahigh-Energy Neutrinos

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

Chiba, M.; Yasuda, O.; Kamijo, T.

2004-11-01

Rock salt and limestone are studied to determine their suitability for use as a radio-wave transmission medium in an ultrahigh energy (UHE) cosmic neutrino detector. A sensible radio wave would be emitted by the coherent Cherenkov radiation from negative excess charges inside an electromagnetic shower upon interaction of a UHE neutrino in a high-density medium (Askar'yan effect). If the attenuation length for the radio wave in the material is large, a relatively small number of radio-wave sensors could detect the interaction occurring in the massive material. We measured the complex permittivity of the rock salt and limestone by the perturbedmore » cavity resonator method at 9.4 and 1 GHz to good precision. We obtained new results of measurements at the frequency at 1.0 GHz. The measured value of the radio-wave attenuation length of synthetic rock salt samples is 1080 m. The samples from the Hockley salt mine in the United States show attenuation length of 180 m at 1 GHz, and then we estimate it by extrapolation to be as long as 900 m at 200 MHz. The results show that there is a possibility of utilizing natural massive deposits of rock salt for a UHE neutrino detector. A salt neutrino detector with a size of 2 x 2 x 2 km would detect 10 UHE neutrino/yr generated through the GZK process.« less

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.

Research on the electromagnetic radiation characteristics of the gas main switch of a capacitive intense electron-beam accelerator

NASA Astrophysics Data System (ADS)

Qiu, Yongfeng; Liu, Jinliang; Yang, Jianhua; Cheng, Xinbing; Li, Guolin

2017-11-01

Strong electromagnetic fields are radiated during the operation of the intense electron-beam accelerator (IEBA), which may lead to the nearby electronic devices out of order. In this paper, the research on the electromagnetic radiation characteristic of the gas main switch of a capacitive IEBA is carried out by the methods of theory analysis and experiment investigation. It is obtained that the gas main switch is the dominating radiation resource. In the absence of electromagnetic shielding for the gas main switch, when the pulse forming line of the IEBA is charged to 700 kV, the radiation field with amplitude of 3280 V/m, dominant frequency of 84 MHz and high frequency 100 MHz is obtained at a distance of 10 meters away from the gas main switch. The experimental results of the radiation field agree with the theoretical calculations. We analyze the achievements of several research groups and find that there is a relationship between the rise time (T) of the transient current of the gas main switch and the dominant frequency (F) of the radiation field, namely, F*T=1. Contrast experiment is carried out with a metal shield cover for the gas main switch. Experimental results show that for the shielded setup the radiation field reduces to 115 V/m, the dominant frequency increases to 86.5 MHz at a distance of 10 away meters from the gas main switch. These conclusions are beneficial for further research on the electromagnetic radiation and protection of the IEBA.

Second dip as a signature of ultrahigh energy proton interactions with cosmic microwave background radiation.

PubMed

Berezinsky, V; Gazizov, A; Kachelrieb, M

2006-12-08

We discuss as a new signature for the interaction of extragalactic ultrahigh energy protons with cosmic microwave background radiation a spectral feature located at E= 6.3 x 10(19) eV in the form of a narrow and shallow dip. It is produced by the interference of e+e(-)-pair and pion production. We show that this dip and, in particular, its position are almost model-independent. Its observation by future ultrahigh energy cosmic ray detectors may give the conclusive confirmation that an observed steepening of the spectrum is caused by the Greisen-Zatsepin-Kuzmin effect.

Exposure of cultured astroglial and microglial brain cells to 900 MHz microwave radiation.

PubMed

Thorlin, Thorleif; Rouquette, Jean-Michel; Hamnerius, Yngve; Hansson, Elisabeth; Persson, Mikael; Björklund, Ulrika; Rosengren, Lars; Rönnbäck, Lars; Persson, Mikael

2006-08-01

The rapid rise in the use of mobile communications has raised concerns about health issues related to low-level microwave radiation. The head and brain are usually the most exposed targets in mobile phone users. In the brain, two types of glial cells, the astroglial and the microglial cells, are interesting in the context of biological effects from microwave exposure. These cells are widely distributed in the brain and are directly involved in the response to brain damage as well as in the development of brain cancer. The aim of the present study was to investigate whether 900 MHz radiation could affect these two different glial cell types in culture by studying markers for damage-related processes in the cells. Primary cultures enriched in astroglial cells were exposed to 900 MHz microwave radiation in a temperature-controlled exposure system at specific absorption rates (SARs) of 3 W/kg GSM modulated wave (mw) for 4, 8 and 24 h or 27 W/kg continuous wave (cw) for 24 h, and the release into the extracellular medium of the two pro-inflammatory cytokines interleukin 6 (Il6) and tumor necrosis factor-alpha (Tnfa) was analyzed. In addition, levels of the astroglial cell-specific reactive marker glial fibrillary acidic protein (Gfap), whose expression dynamics is different from that of cytokines, were measured in astroglial cultures and in astroglial cell-conditioned cell culture medium at SARs of 27 and 54 W/kg (cw) for 4 or 24 h. No significant differences could be detected for any of the parameters studied at any time and for any of the radiation characteristics. Total protein levels remained constant during the experiments. Microglial cell cultures were exposed to 900 MHz radiation at an SAR of 3 W/kg (mw) for 8 h, and I16, Tnfa, total protein and the microglial reactivity marker ED-1 (a macrophage activation antigen) were measured. No significant differences were found. The morphology of the cultured astroglial cells and microglia was studied and appeared to be

High-frequency electric field measurement using a toroidal antenna

DOEpatents

Lee, Ki Ha

2002-01-01

A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

Radiation Performance of Commercial SiGe HBT BiCMOS-High Speed Operational Amplifiers

NASA Technical Reports Server (NTRS)

Chen, Dakai; Pellish, Jonathan; Phan, Anthony; Kim, Hak; Burns, Sam; Albarian, Rafi; Holcombe, Bruce; Little, Bradley; Salzman, James; LaBel, Kenneth

2010-01-01

We present results on heavy-ion and proton irradiations for commercial SiGe BiCMOS operational amplifiers: LTC6400-20 from Linear Technology and THS4304 from Texas Instruments. We found that the devices are susceptible to heavy-ion-induced SETs. The SET cross-sections increase with increasing operating frequency. The LTC6400 exhibits a LET(sub th) < 7.4 MeV·sq cm/mg for frequencies ranging from 10 to 1000 MHz. The THS4304 exhibits a LET(sub th) < 4.4 MeV·sq cm/mg at 200 MHz; the LET(sub th) decreases with increasing frequency. The significance of the SETs also increases with frequency. The SETs at 1000 MHz can erase several signal cycles. We al.so found that the LTC6400 is relatively robust against 198 and 54 MeV protons. We did not observe angular sensitivity from the proton irradiations.

Search for and detection of pulsars inmonitoring observations at 111 MHz

NASA Astrophysics Data System (ADS)

Tyul'bashev, S. A.; Tyul'bashev, V. S.; Kitaeva, M. A.; Chernyshova, A. I.; Malofeev, V. M.; Chashei, I. V.; Shishov, V. I.; Dagkesamanskii, R. D.; Klimenko, S. V.; Nikitin, I. N.; Nikitina, L. D.

2017-10-01

In the course of monitoring interplanetary scintillations of a large number of sources using the Big Scanning Antenna of the Lebedev Physical Institute, a search for pulsars with periods ≥0.4 s at declinations -9◦ < δ < 42◦ and right ascensions 0h < α < 24h was simultaneously carried out. The search was conducted using four years of observations carried out at 110.25MHz in six frequency channels making up a 2.5 MHz band and having a time resolution of 100 ms. The initial identification of pulsar candidates was done using Fourier power spectra averaged over the entire observational period; the pulsar candidates were then verified using observations with higher frequency and time resolution: 32 frequency channels and a time resolution of 12.5 ms. Eighteen new pulsars were discovered in the studied area, whose main characteristics are presented.

Emission characteristics of 6.78-MHz radio-frequency glow discharge plasma in a pulsed mode

NASA Astrophysics Data System (ADS)

Zhang, Xinyue; Wagatsuma, Kazuaki

2017-07-01

This paper investigated Boltzmann plots for both atomic and ionic emission lines of iron in an argon glow discharge plasma driven by 6.78-MHz radio-frequency (RF) voltage in a pulsed operation, in order to discuss how the excitation/ionization process was affected by the pulsation. For this purpose, a pulse frequency as well as a duty ratio of the pulsed RF voltage was selected as the experimenter parameters. A Grimm-style radiation source was employed at a forward RF power of 70 W and at an argon pressures of 670 Pa. The Boltzmann plot for low-lying excited levels of iron atom was on a linear relationship, which was probably attributed to thermal collisions with ultimate electrons in the negative glow region; in this case, the excitation temperature was obtained in a narrow range of 3300-3400 K, which was hardly affected by the duty ratio as well as the pulse frequency of the pulsed RF glow discharge plasma. This observation suggested that the RF plasma could be supported by a self-stabilized negative glow region, where the kinetic energy distribution of the electrons would be changed to a lesser extent. Additional non-thermal excitation processes, such as a Penning-type collision and a charge-transfer collision, led to deviations (overpopulation) of particular energy levels of iron atom or iron ion from the normal Boltzmann distribution. However, their contributions to the overall excitation/ionization were not altered so greatly, when the pulse frequency or the duty ratio was varied in the pulsed RF glow discharge plasma.

A coaxial slot antenna with frequency of 433 MHz for microwave ablation therapies: design, simulation, and experimental research.

PubMed

Jiang, Yingxu; Zhao, Jinzhe; Li, Weitao; Yang, Yamin; Liu, Jia; Qian, Zhiyu

2017-11-01

Investigation of the structures and properties of antennas is important in the design of microwave ablation (MWA) system. In this study, we studied the performance of the novel tri- and single-slot antennas with frequency of 433 MHz in ex vivo conditions. The dielectric properties of liver tissue under different thermal coagulation levels were explored, which was beneficial to evaluate ablation condition of tissue and simulate temperature field. Then, the performances of the antennas were analyzed by using numerical method based on finite element method (FEM). It indicated that the present antennas with frequency of 433 MHz could produce a gourd-shaped MWA area with a longer length. Compared to antenna with frequency of 2450 MHz, the designed single-slot antenna could obtain the larger MWA area. In addition, the multiple-point ablations and a larger MWA area could be achieved simultaneously by using the present tri-slot antenna. This study has a potential for the innovative design of MWA antenna for treatment of liver tumor with a large range and a long length.

Atmospheric-radiation boundary conditions for high-frequency waves in time-distance helioseismology

NASA Astrophysics Data System (ADS)

Fournier, D.; Leguèbe, M.; Hanson, C. S.; Gizon, L.; Barucq, H.; Chabassier, J.; Duruflé, M.

2017-12-01

The temporal covariance between seismic waves measured at two locations on the solar surface is the fundamental observable in time-distance helioseismology. Above the acoustic cut-off frequency ( 5.3 mHz), waves are not trapped in the solar interior and the covariance function can be used to probe the upper atmosphere. We wish to implement appropriate radiative boundary conditions for computing the propagation of high-frequency waves in the solar atmosphere. We consider recently developed and published radiative boundary conditions for atmospheres in which sound-speed is constant and density decreases exponentially with radius. We compute the cross-covariance function using a finite element method in spherical geometry and in the frequency domain. The ratio between first- and second-skip amplitudes in the time-distance diagram is used as a diagnostic to compare boundary conditions and to compare with observations. We find that a boundary condition applied 500 km above the photosphere and derived under the approximation of small angles of incidence accurately reproduces the "infinite atmosphere" solution for high-frequency waves. When the radiative boundary condition is applied 2 Mm above the photosphere, we find that the choice of atmospheric model affects the time-distance diagram. In particular, the time-distance diagram exhibits double-ridge structure when using a Vernazza Avrett Loeser atmospheric model.

Calibration of ultra-high frequency (UHF) partial discharge sensors using FDTD method

NASA Astrophysics Data System (ADS)

Ishak, Asnor Mazuan; Ishak, Mohd Taufiq

2018-02-01

Ultra-high frequency (UHF) partial discharge sensors are widely used for conditioning monitoring and defect location in insulation system of high voltage equipment. Designing sensors for specific applications often requires an iterative process of manufacturing, testing and mechanical modifications. This paper demonstrates the use of finite-difference time-domain (FDTD) technique as a tool to predict the frequency response of UHF PD sensors. Using this approach, the design process can be simplified and parametric studies can be conducted in order to assess the influence of component dimensions and material properties on the sensor response. The modelling approach is validated using gigahertz transverse electromagnetic (GTEM) calibration system. The use of a transient excitation source is particularly suitable for modeling using FDTD, which is able to simulate the step response output voltage of the sensor from which the frequency response is obtained using the same post-processing applied to the physical measurement.

Effects of sintering temperature on properties of toroid cores using NiZnCu ferrites for power applications at >1 MHz

NASA Astrophysics Data System (ADS)

Liu, Junchang; Mei, Yunhui; Liu, Wen; Li, Xin; Hou, Feng; Lu, Guo-Quan

2018-05-01

The microstructures, magnetic and electronic performance of NiZnCu ferrites have been investigated at temperature from 850 °C to 1000 °C. X-ray diffraction (XRD) patterns showed that only single phase with spinel structure existed. Scanning electron microscopy (SEM) results showed that grain size increased with enhancement of sintering temperature and the most homogeneous, compact microstructure was obtained at 950 °C. Magnetic properties measurements revealed that both complex permeability and saturation magnetization increased with increasing of sintering temperature. The initial permeability was approximately linear within the scope of 850-1000 °C as well as the resonance frequency decreased from 70 MHz to 30 MHz. Power loss density tests demonstrated that the core sintered at 950 °C instead of the one sintered at 1000 °C had the lower power loss density at both 5 mT and 10 mT and the higher inductance under a certain exciting direct current at 1 MHz. Also the inductance of the sample sintered at the higher temperature dropped faster than that at the lower temperature. The results showed that the core sintered at 950 °C had better electrical performance and was suitable for wide usage.

A comparison of 10 MHz and 20 MHz ultrasound probes in imaging the eye and orbit.

PubMed

Hewick, S A; Fairhead, A C; Culy, J C; Atta, H R

2004-04-01

/aims: B-scan ultrasonography is an invaluable, versatile, non-invasive tool in ophthalmology. Recently, a "high frequency" contact 20 MHz probe has been introduced. B-scanning ultrasonography of orbital and ocular structures was performed with both a 10 MHz and the new 20 MHz probe, to evaluate what information was best obtained from each probe, and provide recommendations for the use of each. Patients were selected from routine ultrasound clinics at Aberdeen Royal Infirmary between 1 January 2002 and 1 August 2002. The vitreous, retina, choroid, sclera and, in the orbit, the extraocular muscles, optic nerve, and orbital fat were assessed with both the 10 MHz and 20 MHz probes. In the laboratory, using a "point target," the characteristics of the ultrasound beam at different distances from the probe were also assessed. The point target showed that focus was deeper and that the lateral, and to a lesser degree the axial, resolution are sharper with the 20 MHz probe, compared with the 10 MHz probe. In patients' eyes, highly reflective structures are seen at higher resolution with the 20 MHz probe. Imaging of lower intensity reflectors such as the vitreous and particles within it are seen better with the 10 MHz probe. Increased tissue attenuation was evident with the 20 MHz probe. The 20 MHz probe has a superior resolution and can be used to better detect details at the posterior pole and in the orbit. The 10 MHz probe can be used to examine low intensity scatterers, such as the vitreous humour, that cannot be seen using a higher frequency probe.

Low Frequency (11 mHz) Oscillations in H1743-322: A New Class of Black Hole QPOs?

NASA Technical Reports Server (NTRS)

Altamirano, D.; Strohmayer, T.

2012-01-01

We report the discovery of quasi-periodic oscillations (QPO) at approx 11 mHz in two RXTE observations and one Chandra observation of the black hole candidate HI743-322. The QPO is observed only at the beginning of the 2010 and 2011 outbursts at similar hard color and intensity, suggestive of an accretion state dependence for the QPO. Although its frequency appears to be correlated with Xray intensity on timescales of a day, in successive outbursts eight months apart we measure a QPO frequency that differs by less than approximately equals 0.0015 Hz while the intensity had changed significantly. We show that this 11 mHz QPO is different from the so-called Type-C QPOs seen in black holes and that the mechanisms that produce the two flavors of variability are most probably independent. We compare the 11 mHz QPO with other variability phenomena seen in accreting black holes and neutron stars and conclude that although at 1-2 orders of magnitude lower in frequency, they best resemble the so-called "1 Hz" QPOs seen in dipping neutron star systems. If confirmed, H1743-322 is the first black hole showing this type of variability. Given the unusual characteristics and the hard-state dependence of the 11 mHz QPO, we speculate that these oscillations might instead be related to the radio jets observed in HI743-322. It remains unexplained, however, why similar QPOs have not yet been identified in other black holes and why they have only been seen in the last two outbursts of HI743-322.

A multi-MHz single-shot data acquisition scheme with high dynamic range: pump-probe X-ray experiments at synchrotrons.

PubMed

Britz, Alexander; Assefa, Tadesse A; Galler, Andreas; Gawelda, Wojciech; Diez, Michael; Zalden, Peter; Khakhulin, Dmitry; Fernandes, Bruno; Gessler, Patrick; Sotoudi Namin, Hamed; Beckmann, Andreas; Harder, Manuel; Yavaş, Hasan; Bressler, Christian

2016-11-01

The technical implementation of a multi-MHz data acquisition scheme for laser-X-ray pump-probe experiments with pulse limited temporal resolution (100 ps) is presented. Such techniques are very attractive to benefit from the high-repetition rates of X-ray pulses delivered from advanced synchrotron radiation sources. Exploiting a synchronized 3.9 MHz laser excitation source, experiments in 60-bunch mode (7.8 MHz) at beamline P01 of the PETRA III storage ring are performed. Hereby molecular systems in liquid solutions are excited by the pulsed laser source and the total X-ray fluorescence yield (TFY) from the sample is recorded using silicon avalanche photodiode detectors (APDs). The subsequent digitizer card samples the APD signal traces in 0.5 ns steps with 12-bit resolution. These traces are then processed to deliver an integrated value for each recorded single X-ray pulse intensity and sorted into bins according to whether the laser excited the sample or not. For each subgroup the recorded single-shot values are averaged over ∼10 7  pulses to deliver a mean TFY value with its standard error for each data point, e.g. at a given X-ray probe energy. The sensitivity reaches down to the shot-noise limit, and signal-to-noise ratios approaching 1000 are achievable in only a few seconds collection time per data point. The dynamic range covers 100 photons pulse -1 and is only technically limited by the utilized APD.

The Radio Frequency Environment at 240-270 MHz with Application to Signal-of-Opportunity Remote Sensing

NASA Technical Reports Server (NTRS)

Piepmeier, Jeffrey R.; Vega, Manuel; Fritts, Matthew; Du Toit, Cornelis; Knuble, Joseph; Lin, Yao-Cheng; Nold, Benjamin; Garrison, James

2017-01-01

Low frequency observations are desired for soil moisture and biomass remote sensing. Long wavelengths are needed to penetrate vegetation and Earths land surface. In addition to the technical challenges of developing Earth observing spaceflight instruments operating at low frequencies, the radio frequency spectrum allocated to remote sensing is limited. Signal-of-opportunity remote sensing offers the chance to use existing signals exploiting their allocated spectrum to make Earth science measurements. We have made observations of the radio frequency environment around 240-270 MHz and discuss properties of desired and undesired signals.

[The application of low-intensity electromagnetic radiation under immobilization stress conditions (an experimental study)].

PubMed

Korolev, Iu N; Bobrovnitskiĭ, I P; Nikoulina, L A; Mikhaĭlik, L V; Geniatulina, M S; Bobkova, A S

2014-01-01

The experiments carried out on outbred male white rats with the use of optical, electron-microscopic, biochemical, and radioimmunological methods have demonstrated that the application of low-intensity electromagnetic radiation (LI-EMR) with a flow density of 1 mcW/cm2 and a frequency of around 1,000 MHz both in the primary prophylaxis regime and as the therapeuticpreventive modality arrested the development of post-stress disorders in the rat testicles, liver, and thymus; moreover, it promoted activation of the adaptive, preventive, and compensatory processes. The data obtained provide a rationale for the application of low-intensity electromagnetic radiation to protect the organism from negative effects of stressful factors.

47 CFR 90.259 - Assignment and use of frequencies in the bands 216-220 MHz and 1427-1432 MHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... performed in the 1427-1429 MHz and 1431.5-1432 MHz bands. The maximum ERP limitations are as follows...) For all other locations, primary operations are performed in the 1429.5-1432 MHz band. The maximum ERP...

47 CFR 90.355 - LMS operations below 512 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... established, provided that: (a) For transmission between vehicles and base stations, each frequency in a... LMS station and the nearest co-channel base station of another licensee operating a voice system is 75... MHz, 150-170 MHz, and 450-512 MHz bands may use either base-mobile frequencies currently assigned the...

Dielectric relaxation of 1,2,6-hexanetriol at frequencies from 1 mHz to 10 MHz and at pressures to 1 GPa

NASA Astrophysics Data System (ADS)

Forsman, Hans

The complex permittivity of supercooled 1,2,6-hexanetriol has been studied at frequencies from 1 mHz to 10 MHz at pressures up to 1 GPa and at the temperatures 238 K, 248 K and 258 K. The dielectric loss peak is significantly broadened with increasing pressure. A numerical fitting routine has been developed to analyse the results in terms of the Dissado and Hill (DH) cooperative cluster model for relaxation. The peak broadening is explicitly expressed by the shape parameters of the DH theory which are associated with a change in correlation between neighbouring molecules. The relaxation results are also analysed using the Davidson and Cole function. The results of 1,2,6-hexanetriol at high pressure are compared with corresponding data for glycerol. It is found that 1,2,6-hexanetriol exhibits a higher degree of cooperative relaxation according to the DH theory, has a lower static dielectric susceptibility and has a longer characteristic relaxation time than glycerol.

Research and Development of Ultra-High Strength X100 Welded Pipe

NASA Astrophysics Data System (ADS)

Chuanguo, Zhang; Lei, Zheng; Ping, Hu; Bei, Zhang; Kougen, Wu; Weifeng, Huang

Ultra-high strength X100 welded pipe can be used in the construction of long distance oil and gas pipeline to improve transmission capacity and reduce operation cost. By using the way of thermo-simulation and pilot rolling, the CCT (Continuous Cooling Transformation) diagram and the relationship between ACC (Accelerated Cooling) parameters, microstructure and mechanical properties were studied for the designed X100 pipeline steel with low carbon, high manganese and niobium micro-alloyed composition in lab. The analysis of CCT diagram indicates that the suitable hardness and microstructure can be obtained in the cooling rate of 20 80°C/sec. The pilot rolling results show that the ACC cooling start temperature below Ar3 phase transformation point is beneficial to increase uniform elongation, and the cooling stop temperature of 150 350°C is helpful to obtain high strength and toughness combination. Based on the research conclusions, the X100 plate and UOE pipe with dimension in O.D.1219×W.T.14.8mm, O.D.1219×W.T.17.8mm, designed for the natural gas transmission pipeline, were trial produced. The manufactured pipe body impact absorbed energy at -10°C is over 250J. The DWTT shear area ratio at 0°C is over 85%. The transverse strength meets the X100 grade requirement, and uniform elongation is over 4%. The X100 plate and UOE pipe with dimension in O.D.711×W.T.20.0mm, O.D.711×W.T.12.5mm, designed for an offshore engineering, were also trial produced. The average impact absorbed energy of pipe body at -30°C is over 200J. The average impact absorbed energy of HAZ (Heat-affected zone) and WM (Welded Seam) at -30°C is over 100J. And the good pipe shapes were obtained

Radio frequency self-resonant coil for contactless AC-conductivity in 100 T class ultra-strong pulse magnetic fields

NASA Astrophysics Data System (ADS)

Nakamura, D.; Altarawneh, M. M.; Takeyama, S.

2018-03-01

A contactless measurement system of electrical conductivity was developed for application under pulsed high magnetic fields over 100 T by using a self-resonant-type, high-frequency circuit. Electromagnetic fields in the circuit were numerically analysed by the finite element method, to show how the resonant power spectra of the circuit depends on the electrical conductivity of a sample set on the probe-coil. The performance was examined using a high-temperature cuprate superconductor, La2-x Sr x CuO4, in magnetic fields up to 102 T with a high frequency of close to 800 MHz. As a result, the upper critical field could be determined with a good signal-to-noise ratio.

47 CFR 15.245 - Operation within the bands 902-928 MHz, 2435-2465 MHz, 5785-5815 MHz, 10500-10550 MHz, and 24075...

Code of Federal Regulations, 2011 CFR

2011-10-01

... limited to intentional radiators used as field disturbance sensors, excluding perimeter protection systems... field disturbance sensors operating in the 24075-24175 MHz band and for other field disturbance sensors... disturbance sensors, 7.5 mV/m. (iii) Field disturbance sensors designed to be used in motor vehicles or...

47 CFR 15.245 - Operation within the bands 902-928 MHz, 2435-2465 MHz, 5785-5815 MHz, 10500-10550 MHz, and 24075...

Code of Federal Regulations, 2013 CFR

2013-10-01

... limited to intentional radiators used as field disturbance sensors, excluding perimeter protection systems... field disturbance sensors operating in the 24075-24175 MHz band and for other field disturbance sensors... disturbance sensors, 7.5 mV/m. (iii) Field disturbance sensors designed to be used in motor vehicles or...

47 CFR 15.245 - Operation within the bands 902-928 MHz, 2435-2465 MHz, 5785-5815 MHz, 10500-10550 MHz, and 24075...

Code of Federal Regulations, 2014 CFR

2014-10-01

... limited to intentional radiators used as field disturbance sensors, excluding perimeter protection systems... field disturbance sensors operating in the 24075-24175 MHz band and for other field disturbance sensors... disturbance sensors, 7.5 mV/m. (iii) Field disturbance sensors designed to be used in motor vehicles or...

47 CFR 15.245 - Operation within the bands 902-928 MHz, 2435-2465 MHz, 5785-5815 MHz, 10500-10550 MHz, and 24075...

Code of Federal Regulations, 2012 CFR

2012-10-01

... limited to intentional radiators used as field disturbance sensors, excluding perimeter protection systems... field disturbance sensors operating in the 24075-24175 MHz band and for other field disturbance sensors... disturbance sensors, 7.5 mV/m. (iii) Field disturbance sensors designed to be used in motor vehicles or...

An impedance bridge measuring the capacitance ratio in the high frequency range up to 1 MHz

NASA Astrophysics Data System (ADS)

Bee Kim, Dan; Kew Lee, Hyung; Kim, Wan-Seop

2017-02-01

This paper describes a 2-terminal-pair impedance bridge, measuring the capacitance ratio in the high frequency range up to 1 MHz. The bridge was configured with two voltage sources and a phase control unit which enabled the bridge balance by synchronizing the voltage sources with an enhanced phase resolution. Without employing the transformers such as inductive voltage divider, injection and detection transformers, etc, the bridge system is quite simple to set up, and the balance procedure is quick and easy. Using this dual-source coaxial bridge, the 1:1 and 10:1 capacitance ratios were measured with 1 pF-1 nF capacitors in the frequency range from 1 kHz to 1 MHz. The measurement values obtained by the dual-source bridge were then compared with reference values measured using a commercial precision capacitance bridge of AH2700A, the Z-matrix method developed by ourselves, and the 4-terminal-pair coaxial bridge by the Czech Metrological Institute. All the measurements agreed within the reference uncertainty range of an order of 10-6-10-5, proving the bridge ability as a trustworthy tool for measuring the capacitance ratio in the high frequency range.

Absolute backscatter coefficient estimates of tissue-mimicking phantoms in the 5–50 MHz frequency range

PubMed Central

McCormick, Matthew M.; Madsen, Ernest L.; Deaner, Meagan E.; Varghese, Tomy

2011-01-01

Absolute backscatter coefficients in tissue-mimicking phantoms were experimentally determined in the 5–50 MHz frequency range using a broadband technique. A focused broadband transducer from a commercial research system, the VisualSonics Vevo 770, was used with two tissue-mimicking phantoms. The phantoms differed regarding the thin layers covering their surfaces to prevent desiccation and regarding glass bead concentrations and diameter distributions. Ultrasound scanning of these phantoms was performed through the thin layer. To avoid signal saturation, the power spectra obtained from the backscattered radio frequency signals were calibrated by using the signal from a liquid planar reflector, a water-brominated hydrocarbon interface with acoustic impedance close to that of water. Experimental values of absolute backscatter coefficients were compared with those predicted by the Faran scattering model over the frequency range 5–50 MHz. The mean percent difference and standard deviation was 54% ± 45% for the phantom with a mean glass bead diameter of 5.40 μm and was 47% ± 28% for the phantom with 5.16 μm mean diameter beads. PMID:21877789

ECG changes in factory workers exposed to 27.2  MHz radiofrequency radiation.

PubMed

Chen, Qingsong; Xu, Guoyong; Lang, Li; Yang, Aichu; Li, Shilin; Yang, Liwen; Li, Chaolin; Huang, Hanlin; Li, Tao

2013-05-01

To research the effect of 27.2 MHz radiofrequency radiation on electrocardiograms (ECG), 225 female workers operating radiofrequency machines at a shoe factory were chosen as the exposure group and 100 female workers without exposure from the same factory were selected as the control group. The 6 min electric field strength that the female workers were exposed to was 64.0 ± 25.2 V/m (mean ± SD), which exceeded 61 V/m, the International Commission on Non-Ionizing Radiation Protection reference root mean square levels for occupational exposure. A statistical difference was observed between the exposed group and the control group in terms of the rate of sinus bradycardia (χ(2)  = 11.48, P = 0.003). When several known risk factors for cardiovascular disease were considered, including smoking, age, alcohol ingestion habit, and so on, the exposure duration was not an effective factor for ECG changes, sinus arrhythmia, or sinus bradycardia according to α = 0.05, while P = 0.052 for sinus arrhythmia was very close to 0.05. We did not find any statistical difference in heart rate, duration of the QRS wave (ventricular depolarization), or corrected QT intervals (between the start of the Q wave and end of the T wave) between the exposed and control groups. Occupational exposure to radiofrequency radiation was not found to be a cause of ECG changes after consideration of the confounding factors. Copyright © 2012 Wiley Periodicals, Inc.

Micromachined ultrasonic transducers: 11.4 MHz transmission in air and more

NASA Astrophysics Data System (ADS)

Ladabaum, Igal; Khuri-Yakub, B. T.; Spoliansky, Dimitri

1996-01-01

The fabrication and modeling of novel, capacitive, ultrasonic air transducers is reported. Transmission experiments in air at 11.4, 9.2, and 3.1 MHz are shown to correspond with theory. The transducers are made using surface micromachining techniques, which enable the realization of center frequencies ranging from 1.8 to 11.6 MHz. The bandwidth of the transducers ranges from 5% to 20%, depending on processing parameters. Custom circuitry is able to detect 10 MHz capacitance fluctuations as small as 10-18 F, which correspond to displacements on the order of 10-3 Å, in a bandwidth of 2 MHz with a signal to noise ratio of 20 dB. Such detection sensitivity is shown to yield air transducer systems capable of withstanding over 100 dB of signal attenuation, a figure of merit that has significant implications for ultrasonic imaging, nondestructive evaluation, gas flow and composition measurements, and range sensing.

The effects of 2100-MHz radiofrequency radiation on nasal mucosa and mucociliary clearance in rats.

PubMed

Aydoğan, Filiz; Aydın, Emine; Koca, Gökhan; Özgür, Elçin; Atilla, Pergin; Tüzüner, Arzu; Demirci, Şule; Tomruk, Arin; Öztürk, Göknur Güler; Seyhan, Nesrin; Korkmaz, Meliha; Müftüoğlu, Sevda; Samim, Ethem Erdal

2015-07-01

Nasal mucociliary clearance has an important role in voiding the airways from inhaled foreign substances. This activity could be disturbed by environmental factors such as radiofrequency radiation. The aim of the present study was to investigate short-term and relatively long-term effects of 2100-MHz radiofrequency radiation emitted by a generator, simulating a 3G-mobile phone, on the nasal septal mucosa and mucociliary clearance in rats. Thirty Wistar albino rats were divided into 4 groups. There were 6 rats in Group A and Group B, which served as the control groups (10-day and 40-day groups, respectively). Groups C (10-day exposure) and D (40-day exposure) were both composed of 9 rats; they comprised the radiofrequency radiation exposure groups. The rats in groups C and D were exposed to 2100-MHz radiofrequency radiation emitted by a generator, simulating a 3G-mobile phone, 6 hours/day, for 10 or 40 days, respectively. After exposure, nasal mucociliary clearance was measured by rhinoscintigraphy. After euthanization, the nasal septa of the animals were removed, and tissue samples of the nasal mucosa were examined using a transmission electron microscope. The differences in mucociliary clearances between groups A and C, groups B and D, and groups C and D were found to be statistically significant (p = 0.005, p < 0.001, p < 0.001, respectively). Although there were no histopathological abnormalities in the control groups, the exposure groups showed a number of degenerated and apoptotic cells, ciliary disorganization and ciliary loss in the epithelial cells, epithelial metaplasia, alteration of normal chromatin distribution and karyolysis in nuclei, changes in the basal cells, and lymphocytic infiltration. The histopathological changes were more severe in group D. Radiofrequency radiation at 2100 MHz damaged the nasal septal mucosa, and disturbed the mucociliary clearance. Ciliary disorganization and ciliary loss in the epithelial cells resulted in deterioration of

Coherent Frequency Reference System for the NASA Deep Space Network

NASA Technical Reports Server (NTRS)

Tucker, Blake C.; Lauf, John E.; Hamell, Robert L.; Gonzaler, Jorge, Jr.; Diener, William A.; Tjoelker, Robert L.

2010-01-01

The NASA Deep Space Network (DSN) requires state-of-the-art frequency references that are derived and distributed from very stable atomic frequency standards. A new Frequency Reference System (FRS) and Frequency Reference Distribution System (FRD) have been developed, which together replace the previous Coherent Reference Generator System (CRG). The FRS and FRD each provide new capabilities that significantly improve operability and reliability. The FRS allows for selection and switching between frequency standards, a flywheel capability (to avoid interruptions when switching frequency standards), and a frequency synthesis system (to generate standardized 5-, 10-, and 100-MHz reference signals). The FRS is powered by redundant, specially filtered, and sustainable power systems and includes a monitor and control capability for station operations to interact and control the frequency-standard selection process. The FRD receives the standardized 5-, 10-, and 100-MHz reference signals and distributes signals to distribution amplifiers in a fan out fashion to dozens of DSN users that require the highly stable reference signals. The FRD is also powered by redundant, specially filtered, and sustainable power systems. The new DSN Frequency Distribution System, which consists of the FRS and FRD systems described here, is central to all operational activities of the NASA DSN. The frequency generation and distribution system provides ultra-stable, coherent, and very low phase-noise references at 5, l0, and 100 MHz to between 60 and 100 separate users at each Deep Space Communications Complex.

Development of a real-time, high-frequency ultrasound digital beamformer for high-frequency linear array transducers.

PubMed

Hu, Chang-Hong; Xu, Xiao-Chen; Cannata, Jonathan M; Yen, Jesse T; Shung, K Kirk

2006-02-01

A real-time digital beamformer for high-frequency (>20 MHz) linear ultrasonic arrays has been developed. The system can handle up to 64-element linear array transducers and excite 16 channels and receive simultaneously at 100 MHz sampling frequency with 8-bit precision. Radio frequency (RF) signals are digitized, delayed, and summed through a real-time digital beamformer, which is implemented using a field programmable gate array (FPGA). Using fractional delay filters, fine delays as small as 2 ns can be implemented. A frame rate of 30 frames per second is achieved. Wire phantom (20 microm tungsten) images were obtained and -6 dB axial and lateral widths were measured. The results showed that, using a 30 MHz, 48-element array with a pitch of 100 microm produced a -6 dB width of 68 microm in the axial and 370 microm in the lateral direction at 6.4 mm range. Images from an excised rabbit eye sample also were acquired, and fine anatomical structures, such as the cornea and lens, were resolved.

Performance of genotype imputation for low frequency and rare variants from the 1000 genomes.

PubMed

Zheng, Hou-Feng; Rong, Jing-Jing; Liu, Ming; Han, Fang; Zhang, Xing-Wei; Richards, J Brent; Wang, Li

2015-01-01

Genotype imputation is now routinely applied in genome-wide association studies (GWAS) and meta-analyses. However, most of the imputations have been run using HapMap samples as reference, imputation of low frequency and rare variants (minor allele frequency (MAF) < 5%) are not systemically assessed. With the emergence of next-generation sequencing, large reference panels (such as the 1000 Genomes panel) are available to facilitate imputation of these variants. Therefore, in order to estimate the performance of low frequency and rare variants imputation, we imputed 153 individuals, each of whom had 3 different genotype array data including 317k, 610k and 1 million SNPs, to three different reference panels: the 1000 Genomes pilot March 2010 release (1KGpilot), the 1000 Genomes interim August 2010 release (1KGinterim), and the 1000 Genomes phase1 November 2010 and May 2011 release (1KGphase1) by using IMPUTE version 2. The differences between these three releases of the 1000 Genomes data are the sample size, ancestry diversity, number of variants and their frequency spectrum. We found that both reference panel and GWAS chip density affect the imputation of low frequency and rare variants. 1KGphase1 outperformed the other 2 panels, at higher concordance rate, higher proportion of well-imputed variants (info>0.4) and higher mean info score in each MAF bin. Similarly, 1M chip array outperformed 610K and 317K. However for very rare variants (MAF ≤ 0.3%), only 0-1% of the variants were well imputed. We conclude that the imputation of low frequency and rare variants improves with larger reference panels and higher density of genome-wide genotyping arrays. Yet, despite a large reference panel size and dense genotyping density, very rare variants remain difficult to impute.

Mapping the Ice Depth of Europa with Ultrahigh Energy Particles

NASA Astrophysics Data System (ADS)

Romero-Wolf, A.; Naudet, C. J.

2012-12-01

There has been recent interest in applying radio emission of ultra-high energy neutrinos interacting in the ice of Europa. The idea was first described by Gorham (2004)[1] in the context of ultra-high energy particle detection. Shoji, Kurita, and Tanaka (2011)[2] proposed a technique for measuring ice depth using the radio intensity distribution of radio impulses emitted by interactions deep in the Europan ice. Miller, Schaefer, and Sequeira (2012)[3] follow up this study with a simulation of a radio detector mission to constrain the ice depth of Europa. The radio signal results from an effect proposed by Askar'yan (1962)[4] where the particle shower induced by the neutrino interaction accumulates a charge excess traveling faster than the speed of light in the medium and produces a coherent Cherenkov pulse at radio frequencies. We evaluate the feasibility of such a mission given the current state of knowledge of ultra-high energy particle detection and radio pulse production. References [1] Gorham (2004), Planet-sized Detectors for Ultra-high Energy Neutrinos & Cosmic Rays, NASA Advanced Planning Office's Capability Roadmap Public Workshop, Nov. 30, 2004, astro-ph/0411510 [2] Shoji, Kurita, and Tanaka (2011), Constraint of Europan ice thickness by measuring electromagnetic emissions induced by neutrino interaction, Geophysical Research Letters, 38, L08202 [3] Miller, Shaefer, Sequeira, PRIDE (Passive Radio [frequency] Ice Depth Experiment): An instrument to passively measure ice depth from a Europan orbiter using neutrinos, Icarus 220 877-888 [4] Askar'yan (1962), Excess negative charge of an electron photon shower and its coherent radiation originating from it. Radio recording of showers under the ground and on the Moon, Sov. Phys. JETP, 14, 441-443.

INDEX OF PUBLICATIONS ON BIOLOGICAL EFFECTS OF ELECTROMAGNETIC RADIATION (0-100 GHZ)

EPA Science Inventory

Considerable research effort has been made into the biological effects of electro-magnetic radiation over the frequency range of 0-100 GHz. This work intensified since 1966 when occupational exposure guidelines were made by American Standards Institute - C95.9. During this period...

Radiation comb generation with extended Josephson junctions

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

Solinas, P., E-mail: paolo.solinas@spin.cnr.it; Bosisio, R., E-mail: riccardo.bosisio@nano.cnr.it; NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa

2015-09-21

We propose the implementation of a Josephson radiation comb generator based on an extended Josephson junction subject to a time dependent magnetic field. The junction critical current shows known diffraction patterns and determines the position of the critical nodes when it vanishes. When the magnetic flux passes through one of such critical nodes, the superconducting phase must undergo a π-jump to minimize the Josephson energy. Correspondingly, a voltage pulse is generated at the extremes of the junction. Under periodic driving, this allows us to produce a comb-like voltage pulses sequence. In the frequency domain, it is possible to generate upmore » to hundreds of harmonics of the fundamental driving frequency, thus mimicking the frequency comb used in optics and metrology. We discuss several implementations through a rectangular, cylindrical, and annular junction geometries, allowing us to generate different radiation spectra and to produce an output power up to 10 pW at 50 GHz for a driving frequency of 100 MHz.« less

Remote monitoring of emission activity level from NPP using radiofrequencies 1420, 1665, 1667 MHz in real time.

PubMed

Kolotkov, Gennady; Penin, Sergei

2013-01-01

The Fukushima nuclear accident showed the importance of timely monitoring and detection of radioactive emissions released from enterprises of the nuclear fuel cycle. Nuclear power plants (NPP) working continuously are a stationary source of gas-aerosol emissions which presented in a ground surface layer persistently. Following radioactive emission, untypical effects can be observed, for example: the occurrences of areas with increased ionization, and increased concentration of some gases caused by photochemical reactions. The gases themselves and their characteristic radiation can be markers of radioactivity and can be monitored by a passive method. Hydrogen atom (H) and hydroxyl radical (OH) are formed in a radioactive plume by radiolysis of water molecules and other hydrogen-containing air components by the high energy electrons from beta-decay of radionuclides. The hydrogen atom and hydroxyl radical can spontaneously radiate at 1420 MHz and 1665-1667 MHz respectively. The passive method of remote monitoring of radiation levels using radio-frequencies of H and OH from radioactive emissions of NPP is described. The model data is indicative of the monitoring of radiation levels using these frequencies. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Study of complex permittivity spectra of binary mixtures of 2-chloroaniline and methanol in frequency range 10 KHz to 2 MHz at different temperatures

NASA Astrophysics Data System (ADS)

Shah, N. S.; Vankar, H. P.; Rana, V. A.

2017-05-01

The complex relative dielectric function ɛ*(ω)=ɛ'-jɛ″ of the binary mixture of 2-chloroaniline(2-CA) and methanol (MeOH) were measured using precision LCR meter in the frequency range of 10 KHz to 2 MHz The measurements were carried out at eight different temperatures and five different concentrations of 2-CA and MeOH. The loss tangent peaks were observed in the studied frequency range for all the binary mixtures. From the loss tangent peaks electrode polarization relaxation time were evaluated. In the plot of real part of complex permittivity against frequency, at different temperatures for 2-CA (54.54%) + MeOH (45.45%) and 2-CA (27.27%) + MeOH (72.72%)and 100% MeOH systems permittivity inversion effect was observed.

High-resolution simulations of the thermophysiological effects of human exposure to 100 MHz RF energy

NASA Astrophysics Data System (ADS)

Nelson, David A.; Curran, Allen R.; Nyberg, Hans A.; Marttila, Eric A.; Mason, Patrick A.; Ziriax, John M.

2013-03-01

Human exposure to radio frequency (RF) electromagnetic energy is known to result in tissue heating and can raise temperatures substantially in some situations. Standards for safe exposure to RF do not reflect bio-heat transfer considerations however. Thermoregulatory function (vasodilation, sweating) may mitigate RF heating effects in some environments and exposure scenarios. Conversely, a combination of an extreme environment (high temperature, high humidity), high activity levels and thermally insulating garments may exacerbate RF exposure and pose a risk of unsafe temperature elevation, even for power densities which might be acceptable in a normothermic environment. A high-resolution thermophysiological model, incorporating a heterogeneous tissue model of a seated adult has been developed and used to replicate a series of whole-body exposures at a frequency (100 MHz) which approximates that of human whole-body resonance. Exposures were simulated at three power densities (4, 6 and 8 mW cm-2) plus a sham exposure and at three different ambient temperatures (24, 28 and 31 °C). The maximum hypothalamic temperature increase over the course of a 45 min exposure was 0.28 °C and occurred in the most extreme conditions (Tamb = 31 °C, PD = 8 mW cm-2). Skin temperature increases attributable to RF exposure were modest, with the exception of a ‘hot spot’ in the vicinity of the ankle where skin temperatures exceeded 39 °C. Temperature increases in internal organs and tissues were small, except for connective tissue and bone in the lower leg and foot. Temperature elevation also was noted in the spinal cord, consistent with a hot spot previously identified in the literature.

High-resolution simulations of the thermophysiological effects of human exposure to 100 MHz RF energy.

PubMed

Nelson, David A; Curran, Allen R; Nyberg, Hans A; Marttila, Eric A; Mason, Patrick A; Ziriax, John M

2013-03-21

Human exposure to radio frequency (RF) electromagnetic energy is known to result in tissue heating and can raise temperatures substantially in some situations. Standards for safe exposure to RF do not reflect bio-heat transfer considerations however. Thermoregulatory function (vasodilation, sweating) may mitigate RF heating effects in some environments and exposure scenarios. Conversely, a combination of an extreme environment (high temperature, high humidity), high activity levels and thermally insulating garments may exacerbate RF exposure and pose a risk of unsafe temperature elevation, even for power densities which might be acceptable in a normothermic environment. A high-resolution thermophysiological model, incorporating a heterogeneous tissue model of a seated adult has been developed and used to replicate a series of whole-body exposures at a frequency (100 MHz) which approximates that of human whole-body resonance. Exposures were simulated at three power densities (4, 6 and 8 mW cm(-2)) plus a sham exposure and at three different ambient temperatures (24, 28 and 31 °C). The maximum hypothalamic temperature increase over the course of a 45 min exposure was 0.28 °C and occurred in the most extreme conditions (T(AMB) = 31 °C, PD = 8 mW cm(-2)). Skin temperature increases attributable to RF exposure were modest, with the exception of a 'hot spot' in the vicinity of the ankle where skin temperatures exceeded 39 °C. Temperature increases in internal organs and tissues were small, except for connective tissue and bone in the lower leg and foot. Temperature elevation also was noted in the spinal cord, consistent with a hot spot previously identified in the literature.

Ultra-high resolution water window x ray microscope optics design and analysis

NASA Technical Reports Server (NTRS)

Shealy, David L.; Wang, C.

1993-01-01

This project has been focused on the design and analysis of an ultra-high resolution water window soft-x-ray microscope. These activities have been accomplished by completing two tasks contained in the statement of work of this contract. The new results from this work confirm: (1) that in order to achieve resolutions greater than three times the wavelength of the incident radiation, it will be necessary to use spherical mirror surfaces and to use graded multilayer coatings on the secondary in order to accommodate the large variations of the angle of incidence over the secondary when operating the microscope at numerical apertures of 0.35 or greater; (2) that surface contour errors will have a significant effect on the optical performance of the microscope and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror; and (3) that tolerance analysis of the spherical Schwarzschild microscope has been shown that the water window operations will require 2-3 times tighter tolerances to achieve a similar performance of operations with 130 A radiation. These results have been included in a manuscript included in the appendix.

Nonequilibrium atmospheric pressure plasma jet using a combination of 50 kHz/2 MHz dual-frequency power sources

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

Zhou, Yong-Jie; Yuan, Qiang-Hua; Li, Fei

2013-11-15

An atmospheric pressure plasma jet is generated by dual sinusoidal wave (50 kHz and 2 MHz). The dual-frequency plasma jet exhibits the advantages of both low frequency and radio frequency plasmas, namely, the long plasma plume and the high electron density. The radio frequency ignition voltage can be reduced significantly by using dual-frequency excitation compared to the conventional radio frequency without the aid of the low frequency excitation source. A larger operating range of α mode discharge can be obtained using dual-frequency excitation which is important to obtain homogeneous and low-temperature plasma. A larger controllable range of the gas temperaturemore » of atmospheric pressure plasma could also be obtained using dual-frequency excitation.« less

Wide field polarimetry around the Perseus cluster at 350 MHz

NASA Astrophysics Data System (ADS)

Brentjens, M. A.

2011-02-01

Aims: This paper investigates the fascinating diffuse polarization structures at 350 MHz that have previously been tentatively attributed to the Perseus cluster and, more specifically, tries to find out whether the structures are located at (or near) the Perseus cluster, or in the Milky Way. Methods: A wide field, eight point Westerbork Synthesis Radio Telescope mosaic of the area around the Perseus cluster was observed in full polarization. The frequency range was 324 to 378 MHz and the resolution of the polarization maps was 2' × 3'. The maps were processed using Faraday rotation measure synthesis to counter bandwidth depolarization. The RM-cube covers Faraday depths of -384 to +381 rad m-2 in steps of 3 rad m-2. Results: There is emission all over the field at Faraday depths between -50 and +100 rad m-2. All previously observed structures were detected. However, no compelling evidence was found supporting association of those structures with either the Perseus cluster or large scale structure formation gas flows in the Perseus-Pisces super cluster. On the contrary, one of the structures is clearly associated with a Galactic depolarization canal at 1.41 GHz. Another large structure in polarized intensity, as well as Faraday depth at a Faraday depth of +30 rad m-2, coincides with a dark object in WHAM Hα maps at a kinematic distance of 0.5 ± 0.5 kpc. All diffuse polarized emission at 350 MHz towards the Perseus cluster is most likely located within 1 kpc from the Sun. The layers that emit the polarized radiation are less than 40 pc/|B_∥| thick. Appendix is only available in electronic form at http://www.aanda.org

Wireless communication link for capsule endoscope at 600 MHz.

PubMed

Khaleghi, A; Balasingham, I

2015-01-01

Simulation of a wireless communication link for a capsule endoscopy is presented for monitoring of small intestine in humans. The realized communication link includes the transmitting capsule antenna, the outside body receiving antenna and the model of the human body. The capsule antenna is designed for operating at the frequency band of 600 MHz with an impedance bandwidth of 10 MHz and omnidirectional radiation pattern. The quality of the communication link is improved by using directive antenna outside body inside matching layer for electromagnetic wave tuning to the body. The outside body antenna has circular polarization that guaranteeing the communication link for different orientations of the capsule inside intestine. It is shown that the path loss for the capsule in 60 mm from the abdomen surface varies between 37-47 dB in relation to the antenna orientation. This link can establish high data rate wireless communications for capsule endoscopy.

On the Variation of Eta with Energy in the 100-1000 ev Region

DOE R&D Accomplishments Database

Wigner, E. P.

1949-11-01

Fluctuations in the fission yield in the 100- to 1000-ev region led to an investigation of the influencing variables. Changes in fission width from level to level and higher angular momentum phenomena are seen as possible explanations. (D.E.B.)

47 CFR 76.610 - Operation in the frequency bands 108-137 and 225-400 MHz-scope of application.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 47 Telecommunication 4 2011-10-01 2011-10-01 false Operation in the frequency bands 108-137 and 225-400 MHz-scope of application. 76.610 Section 76.610 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES MULTICHANNEL VIDEO AND CABLE TELEVISION SERVICE Technical...

Calculations of low-frequency radio emission by cosmic-ray-induced particle showers

NASA Astrophysics Data System (ADS)

García-Fernández, Daniel; Revenu, Benoît; Charrier, Didier; Dallier, Richard; Escudie, Antony; Martin, Lilian

2018-05-01

The radio technique for the detection of high-energy cosmic rays consists in measuring the electric field created by the particle showers created inside a medium by the primary cosmic ray. The electric field is then used to infer the properties of the primary particle. Nowadays, the radio technique is a standard, well-established technique. While most current experiments measure the field at frequencies above 20 MHz, several experiments have reported a large emission at low frequencies, below 10 MHz. The EXTASIS experiment aims at measuring again and understanding this low-frequency electric field. Since at low frequencies the standard far-field approximation for the calculation of the electric field does not necessarily hold, in order to comprehend the low-frequency emission we need to go beyond the far-field approximation. We present in this work a formula for the electric field created by a particle track inside a dielectric medium that is valid for all frequencies. We then implement this formula in the SELFAS Monte Carlo code and calculate the low-frequency electric field of the extensive air shower (EAS). We also study the electric field of a special case of the transition radiation mechanism when the EAS particles cross the air-soil boundary. We introduce the sudden death pulse, the direct emission caused by the coherent deceleration of the shower front at the boundary, as a first approximation to the whole electric field for the air-soil transition, and study its properties. We show that at frequencies larger than 20 MHz and distances larger than 100 m, the standard far-field approximation for the horizontal polarizations of the field is always accurate at the 1% level.

75 MHz Ultrasound Biomicroscopy of Anterior Segment of Eye

PubMed Central

Silverman, Ronald H.; Cannata, Jonathan; Shung, K. Kirk; Gal, Omer; Patel, Monica; Lloyd, Harriet O.; Feleppa, Ernest J.; Coleman, D. Jackson

2006-01-01

Very high frequency ultrasound (35–50 MHz) has had a significant impact upon clinical imaging of the anterior segment of the eye, offering an axial resolution as small as 30 μm. Higher frequencies, while potentially offering even finer resolution, are more affected by absorption in ocular tissues and even in the fluid coupling medium. Our aim was to develop and apply improved transducer technology utilizing frequencies beyond those routinely used for ultrasound biomicroscopy of the eye. A 75-MHz lithium niobate transducer with 2 mm aperture and 6 mm focal length was fabricated. We scanned the ciliary body and cornea of a human eye six years post-LASIK. Spectral parameter images were produced from the midband fit to local calibrated power spectra. Images were compared with those produced using a 35 MHz lithium niobate transducer of similar fractional bandwidth and focal ratio. The 75-MHz transducer was found to have a fractional bandwidth (−6 dB) of 61%. Images of the post-LASIK cornea showed higher stromal backscatter at 75 MHz than at 35 MHz. The improved lateral resolution resulted in better visualization of discontinuities in Bowman’s layer, indicative of microfolds or breaks occurring at the time of surgery. The LASIK surface was evident as a discontinuity in stromal backscatter between the stromal component of the flap and the residual stroma. The iris and ciliary body were visualized despite attenuation by the overlying sclera. Very high frequency ultrasound imaging of the anterior segment of the eye has been restricted to the 35–50 MHz band for over a decade. We showed that higher frequencies can be used in vivo to image the cornea and anterior segment. This improvement in resolution and high sensitivity to backscatter from the corneal stroma will provide benefits in clinical diagnostic imaging of the anterior segment. PMID:17147058

75 MHz ultrasound biomicroscopy of anterior segment of eye.

PubMed

Silverman, Ronald H; Cannata, Jonathan; Shung, K Kirk; Gal, Omer; Patel, Monica; Lloyd, Harriet O; Feleppa, Ernest J; Coleman, D Jackson

2006-07-01

Very high frequency ultrasound (35-50 MHz) has had a significant impact upon clinical imaging of the anterior segment of the eye, offering an axial resolution as small as 30 microm. Higher frequencies, while potentially offering even finer resolution, are more affected by absorption in ocular tissues and even in the fluid coupling medium. Our aim was to develop and apply improved transducer technology utilizing frequencies beyond those routinely used for ultrasound biomicroscopy of the eye. A 75-MHz lithium niobate transducer with 2 mm aperture and 6 mm focal length was fabricated. We scanned the ciliary body and cornea of a human eye six years post-LASIK. Spectral parameter images were produced from the midband fit to local calibrated power spectra. Images were compared with those produced using a 35 MHz lithium niobate transducer of similar fractional bandwidth and focal ratio. The 75-MHz transducer was found to have a fractional bandwidth (-6 dB) of 61%. Images of the post-LASIK cornea showed higher stromal backscatter at 75 MHz than at 35 MHz. The improved lateral resolution resulted in better visualization of discontinuities in Bowman's layer, indicative of microfolds or breaks occurring at the time of surgery. The LASIK surface was evident as a discontinuity in stromal backscatter between the stromal component of the flap and the residual stroma. The iris and ciliary body were visualized despite attenuation by the overlying sclera. Very high frequency ultrasound imaging of the anterior segment of the eye has been restricted to the 35-50 MHz band for over a decade. We showed that higher frequencies can be used in vivo to image the cornea and anterior segment. This improvement in resolution and high sensitivity to backscatter from the corneal stroma will provide benefits in clinical diagnostic imaging of the anterior segment.

Frequency chirped light at large detuning with an injection-locked diode laser

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

Teng, K.; Disla, M.; Dellatto, J.

2015-04-15

We have developed a laser system to generate frequency-chirped light at rapid modulation speeds (∼100 MHz) with a large frequency offset. Light from an external cavity diode laser with its frequency locked to an atomic resonance is passed through a lithium niobate electro-optical phase modulator. The phase modulator is driven by a ∼6 GHz signal whose frequency is itself modulated with a RF MHz signal (<200 MHz). A second injection locked diode laser is used to filter out all of the light except the frequency-chirped ±1 order by more than 30 dB. Using this system, it is possible to generatemore » a 1 GHz frequency chirp in 5 ns.« less

Effect of Short-term 900 MHz low level electromagnetic radiation exposure on blood serotonin and glutamate levels.

PubMed

Eris, A H; Kiziltan, H S; Meral, I; Genc, H; Trabzon, M; Seyithanoglu, H; Yagci, B; Uysal, O

2015-01-01

Long term exposure to low level electromagnetic radiation (LLER) by using cellular phones causes serious health problems. Ten male Wistar Albino rats were anesthetized 30 min before the LLER exposure, 0.5 ml blood was taken from the tail vein of rats in order to determine control values. Rats were grouped by three and placed on a plexi-glass flat. A fixed equivalent frequency emitter device was used. A sign to be an electromagnetic field 15.14 V/m (608 mW/m(2)) in strength in the head region with 100 kHz FM modulation at 900 MHz was applied to the animals. After calculating the ideal position for the device, electromagnetic LLER energy was applied for 45 minutes from a distance to be equal with energy transmitted by a mobile phone from a 0.5-1 cm distance to their head regions. After 1.5 hours and before the rats awoke, 0.5 ml of blood was taken from the tail veins in order to determine the treatment values. Plasma 5-HT and glutamate levels were measured by enzyme immunoassay (EIA) using commercial kits. It was found that a single 45 min of LLER exposure increased the blood 5-HT level significantly, but did not change the glutamate level of rats. It was concluded that even a single 45 min of LLER exposure may produce an increase in 5-HT level without changing the blood glutamate level. Increased 5-HT level may lead to a retarded learning and a deficit in spatial memory (Tab. 2, Fig. 2, Ref. 24).

Effects of Long Term Exposure of 900-1800 MHz Radiation Emitted from 2G Mobile Phone on Mice Hippocampus- A Histomorphometric Study.

PubMed

Mugunthan, Narayanaperumal; Shanmugasamy, Kathirvelu; Anbalagan, Jayaram; Rajanarayanan, Swamynathan; Meenachi, Swamynathan

2016-08-01

The advancement in the telecommunications technology with multi-functional added features in mobile phone, attracts more users of all age group. It is alarming to note that, the mobile phone use has increased amongst children and they are exposed to potentially harmful radiofrequency radiation in their lifetime. To investigate the long term exposure of 900 to 1800 MHz radiations emitted from 2G mobile phone in mice hippocampus at histomorphometric level. With due approval from institutional animal ethics committee, 36 mice were exposed to 2G mobile phone radiation, 48 minutes per day for a period of 30-180 days. The control group was kept under similar conditions without 2G exposure. Mice were sacrificed and the brain was removed from the first month to six months period. Brain was removed from the cranial cavity and hippocampus region was dissected out carefully and processed for routine histological study. Random serial sections were analysed under microscope for histomorphometric changes. For statistical analysis, independent t-test was used for comparing control and 2G exposed groups. The mean density of neurons in the hippocampus regions CA1, CA2 and DGDB from first to sixth month was significantly lower in the 2G exposed groups; however, in CA3 and DGVB, the 2G exposed mice showed significantly higher density of neurons. The mean nuclear diameter of neurons in the hippocampus region of CA1, CA2, CA3, DGDB and DGVB from first to sixth months showed lower nuclear diameter in 2G exposed mice. The long term exposure to 900-1800 MHz frequency radiations emitted from 2G mobile phone could cause significantly reduced neuron density and decreased nuclear diameter in the hippocampus neurons of mice.

Effects of Long Term Exposure of 900-1800 MHz Radiation Emitted from 2G Mobile Phone on Mice Hippocampus- A Histomorphometric Study

PubMed Central

Shanmugasamy, Kathirvelu; Anbalagan, Jayaram; Rajanarayanan, Swamynathan; Meenachi, Swamynathan

2016-01-01

Introduction The advancement in the telecommunications technology with multi-functional added features in mobile phone, attracts more users of all age group. It is alarming to note that, the mobile phone use has increased amongst children and they are exposed to potentially harmful radiofrequency radiation in their lifetime. Aim To investigate the long term exposure of 900 to 1800 MHz radiations emitted from 2G mobile phone in mice hippocampus at histomorphometric level. Materials and Methods With due approval from institutional animal ethics committee, 36 mice were exposed to 2G mobile phone radiation, 48 minutes per day for a period of 30-180 days. The control group was kept under similar conditions without 2G exposure. Mice were sacrificed and the brain was removed from the first month to six months period. Brain was removed from the cranial cavity and hippocampus region was dissected out carefully and processed for routine histological study. Random serial sections were analysed under microscope for histomorphometric changes. For statistical analysis, independent t-test was used for comparing control and 2G exposed groups. Results The mean density of neurons in the hippocampus regions CA1, CA2 and DGDB from first to sixth month was significantly lower in the 2G exposed groups; however, in CA3 and DGVB, the 2G exposed mice showed significantly higher density of neurons. The mean nuclear diameter of neurons in the hippocampus region of CA1, CA2, CA3, DGDB and DGVB from first to sixth months showed lower nuclear diameter in 2G exposed mice. Conclusion The long term exposure to 900-1800 MHz frequency radiations emitted from 2G mobile phone could cause significantly reduced neuron density and decreased nuclear diameter in the hippocampus neurons of mice. PMID:27656427

Detection of Linear Polarization from SNR Cassiopeia A at Low Radio Frequencies

NASA Astrophysics Data System (ADS)

Raja, Wasim; Deshpande, Avinash A.

2015-03-01

We report detection of the weak but significant linear polarization from the Supernova Remnant Cas A at low radio frequencies (327 MHz) using the GMRT. The spectro-polarimetric data (16 MHz bandwidth with 256 spectral channels) was analyzed using the technique of Faraday Tomography. Ascertaining association of this weak polarization to the source is non-trivial in the presence of the remnant instrumental polarization (<1% in our case) - the expected anti-correlation ρlp,x, between the linear polarized intensity and the soft X-ray counts gets masked by the correlation between the Stokes-I dependent instrumental leakage and the X-radiation that is spatially correlated with Stokes-I, if ρ lp,x is computed naively. Hence, we compute ρ lp,x using pixels within ultra narrow bins of Stokes-I within which the instrumental leakage is expected to remain constant, and establish the anti-correlation as well as the correspondence of this correlation with the mean X-ray profile (Figure 1). Given the angular and RM-resolution in our data, the observed depolarization relative to that at higher frequencies, implies that the mixing of thermal and non-thermal plasma within the source might be occurring on spatial scales ~ 1000 AU, assuming random superposition of polarization states.

Initial Demonstration of 9-MHz Framing Camera Rates on the FAST UV Drive Laser Pulse Trains

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

Lumpkin, A. H.; Edstrom Jr., D.; Ruan, J.

2016-10-09

We report the configuration of a Hamamatsu C5680 streak camera as a framing camera to record transverse spatial information of green-component laser micropulses at 3- and 9-MHz rates for the first time. The latter is near the time scale of the ~7.5-MHz revolution frequency of the Integrable Optics Test Accelerator (IOTA) ring and its expected synchroton radiation source temporal structure. The 2-D images are recorded with a Gig-E readout CCD camera. We also report a first proof of principle with an OTR source using the linac streak camera in a semi-framing mode.

Development of a 20-MHz wide-bandwidth PMN-PT single crystal phased-array ultrasound transducer.

PubMed

Wong, Chi-Man; Chen, Yan; Luo, Haosu; Dai, Jiyan; Lam, Kwok-Ho; Chan, Helen Lai-Wa

2017-01-01

In this study, a 20-MHz 64-element phased-array ultrasound transducer with a one-wavelength pitch is developed using a PMN-30%PT single crystal and double-matching layer scheme. High piezoelectric (d 33 >1000pC/N) and electromechanical coupling (k 33 >0.8) properties of the single crystal with an optimized fabrication process involving the photolithography technique have been demonstrated to be suitable for wide-bandwidth (⩾70%) and high-sensitivity (insertion loss ⩽30dB) phased-array transducer application. A -6dBbandwidth of 91% and an insertion loss of 29dBfor the 20-MHz 64-element phased-array transducer were achieved. This result shows that the bandwidth is improved comparing with the investigated high-frequency (⩾20MHz) ultrasound transducers using piezoelectric ceramic and single crystal materials. It shows that this phased-array transducer has potential to improve the resolution of biomedical imaging, theoretically. Based on the hypothesis of resolution improvement, this phased-array transducer is capable for small animal (i.e. mouse and zebrafish) studies. Copyright © 2016 Elsevier B.V. All rights reserved.

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.

47 CFR 27.17 - Discontinuance of service in the 1695-1710 MHz, 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000...

Code of Federal Regulations, 2014 CFR

2014-10-01

..., 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000-2020 MHz, 2155-2180 MHz, and 2180-2200 MHz bands. 27... service in the 1695-1710 MHz, 1755-1780 MHz, 1915-1920 MHz, 1995-2000 MHz, 2000-2020 MHz, 2155-2180 MHz... MHz, 2000-2020 MHz, 2155-2180 MHz, and 2180-2200 MHz bands will automatically terminate, without...

Galactic background maps at 3.93 and 6.55 MHz. M.S. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Novaco, J. C.

1973-01-01

The Radio Astronomy Explorer Satellite (RAE-1), its hardware and its data processing are discussed. The data from the prime mapping antenna are discussed with emphasis on the problems involved in reducing the data. Particular attention is drawn to two problems - receiver instability and ground breakthrough - and their influence on the data. Galactic background maps of the nonthermal radiation at 3.93 and 6.55 MHz are produced. It is demonstrated that the positional uncertainity of the maps is about 20 deg. The maps at 3.93 and 6.55 MHz are compared to two ground based maps made at higher frequencies that are smoothed to the larger RAE antenna patterns.

Induction of adaptive response in human blood lymphocytes exposed to radiofrequency radiation.

PubMed

Sannino, Anna; Sarti, Maurizio; Reddy, Siddharth B; Prihoda, Thomas J; Vijayalaxmi; Scarfì, Maria Rosaria

2009-06-01

The incidence of micronuclei was evaluated to assess the induction of an adaptive response to non-ionizing radiofrequency (RF) radiation in peripheral blood lymphocytes collected from five different human volunteers. After stimulation with phytohemagglutinin for 24 h, the cells were exposed to an adaptive dose of 900 MHz RF radiation used for mobile communications (at a peak specific absorption rate of 10 W/kg) for 20 h and then challenged with a single genotoxic dose of mitomycin C (100 ng/ml) at 48 h. Lymphocytes were collected at 72 h to examine the frequency of micronuclei in cytokinesis-blocked binucleated cells. Cells collected from four donors exhibited the induction of adaptive response (i.e., responders). Lymphocytes that were pre-exposed to 900 MHz RF radiation had a significantly decreased incidence of micronuclei induced by the challenge dose of mitomycin C compared to those that were not pre-exposed to 900 MHz RF radiation. These preliminary results suggested that the adaptive response can be induced in cells exposed to non-ionizing radiation. A similar phenomenon has been reported in cells as well as in animals exposed to ionizing radiation in several earlier studies. However, induction of adaptive response was not observed in the remaining donor (i.e., non-responder). The incidence of micronuclei induced by the challenge dose of mitomycin C was not significantly different between the cells that were pre-exposed and unexposed to 900 MHz RF radiation. Thus the overall data indicated the existence of heterogeneity in the induction of an adaptive response between individuals exposed to RF radiation and showed that the less time-consuming micronucleus assay can be used to determine whether an individual is a responder or non-responder.

A 1-MHz 2-D CMUT array for HIFU thermal ablation

NASA Astrophysics Data System (ADS)

Yoon, Hyo-Seon; Vaithilingam, Srikant; Park, Kwan Kyu; Nikoozadeh, Amin; Firouzi, Kamyar; Choe, Jung Woo; Watkins, Ronald D.; Oguz, Huseyin Kagan; Kupnik, Mario; Pauly, Kim Butts; Khuri-Yakub, Pierre

2017-03-01

We developed a fully-populated 2-D capacitive micromachined ultrasonic transducer (CMUT) array for high intensity focused ultrasound (HIFU) treatment. The 2-D CMUT array, which consists of 20 × 20 square CMUT elements with an element-to-element pitch of 1 mm, was designed and fabricated using the thick-buried-oxide (BOX) fabrication process. It was then assembled on a custom interface board that can provide various array configurations depending on the desired applications. In this study, the interface board groups the CMUT array elements into eight channels, based on the phase delay from the element to the targeted focal point at a 20-mm distance from the array surface, which corresponds to an F-number of 1. An 8-channel phase generating system supplies continuous waves with eight different phases to the eight channels of the CMUT array through bias-tees and amplifiers. This array aperture, grouped into eight channels, gives a focusing gain of 6.09 according to field simulation using Field II. Assuming a peak-to-peak pressure of 1 MPa at the surface of the array, our custom temperature simulator predicts successful tissue ablation at the focus. During the measurements, each channel was tuned with a series inductor for an operational frequency of 1 MHz. With a CMUT DC bias of 100 V and a 1-MHz AC input voltage of 55 V, we achieved peak-to-peak output pressures of 173.9 kPa and 568.7 kPa at the array surface and at the focus, respectively. The focusing gain calculated from this measurement is 3.27, which is lower than the simulated gain of 6.09 because of the mutual radiation impedance among the CMUT cells. Further optimization of the operating condition of this array and design improvements for reducing the effect of mutual radiation impedance are currently on-going.

Measurement and analysis of radiofrequency radiations from some mobile phone base stations in Ghana.

PubMed

Amoako, J K; Fletcher, J J; Darko, E O

2009-08-01

A survey of the radiofrequency electromagnetic radiation at public access points in the vicinity of 50 cellular phone base stations has been carried out. The primary objective was to measure and analyse the electromagnetic field strength levels emitted by antennae installed and operated by the Ghana Telecommunications Company. On all the sites measurements were made using a hand-held spectrum analyser to determine the electric field level with the 900 and 1800 MHz frequency bands. The results indicated that power densities at public access points varied from as low as 0.01 microW m(-2) to as high as 10 microW m(-2) for the frequency of 900 MHz. At a transmission frequency of 1800 MHz, the variation of power densities is from 0.01 to 100 microW m(-2). The results were found to be in compliant with the International Commission on Non-ionizing Radiological Protection guidance level but were 20 times higher than the results generally obtained for such a practice elsewhere. There is therefore a need to re-assess the situation to ensure reduction in the present level as an increase in mobile phone usage is envisaged within the next few years.

47 CFR 90.355 - LMS operations below 512 MHz.

Code of Federal Regulations, 2011 CFR

2011-10-01

... PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.355 LMS... LMS station and the nearest co-channel base station of another licensee operating a voice system is 75... MHz, 150-170 MHz, and 450-512 MHz bands may use either base-mobile frequencies currently assigned the...

Probe And Enhancement Of SBS Based Phonons In Infrared Fibers Using Waveguide Coupled External Radiation

NASA Astrophysics Data System (ADS)

Yu, Chung; Chong, Yat C.; Fong, Chee K.

1989-06-01

Interaction of GHz and MHz radiation with CO2 laser propagation in a silver halide fiber using sBs based phonon coupling is furthet investigated. The external signal serves to both probe and enhance laser generated sBs phonons in the fiber. Efficient coupling of microwave radiation into the fiber is accomplished by placing the fiber in a hollow metallic waveguide, designed and constructed to transmit the dominant mode in the 0.9-2.0 GHz band. MHz radiation is conveniently coupled into the fiber using the guided microwave radiation as carrier. Phonon emissions from the fiber under CO2 laser pumping are first established on a spectrum analyzer; low frequency generators ale then tuned to match these frequencies and their maximum interaction recorded. Such interactions are systematically studied by monitoring the amplitude and waveform of the reflected and transmitted laser pulse at various power levels and frequencies of the externally coupled radiation. A plot of reflected laser power versus incident laser power reveals a distinct sBs generated phonon threshold. Variouslaunch directions of the GHz and MHz radiation with respect to the direction of laser propagation are realized to verify theory governing sBs interactions. The MHz radiation and its associated phonons in the fiber are convenient tools for probing sBs related phenomenon in infrared fibers.

Electromagnetic Radiation from Corona Discharges.

DTIC Science & Technology

1977-01-25

a 3 MHz bandwidth to cover frequencies below I GHz. Various TWT preamplifiers were used to increase the system gain. R-f energy from the corona point...100 MHz CENTER FREQUENCYr 0.05 mv/div 5 ps/div FIGURE 11. DETECTED I.F SIGNALS RECEIVED FROM A 20’ PIPE IN CORONA 29 the broadband impulsive background...noise at sea, with a secondary objective of measuring background noise at narrower bandwidths on a swept frequency basis. The broadband measurement

Electromagnetic emission from terrestrial lightning in the 0.1-30 MHz frequency range

NASA Astrophysics Data System (ADS)

Karashtin, A. N.; Gurevich, A. V.

Results of measurements carried out at SURA facility of Radiophisical Research Institute and at Tien-Shan Mountain Scientific Station of Lebedev Physical Institute using specially designed installations for short electromagnetic pulse observation in the frequency range from 0.1 to 30 MHz are presented. Specific attention is paid to initial stage of the lightning discharge. It is shown that lightning can be initiated by extensive atmospheric showers caused by high energy cosmic ray particles. Analysis of emission of few thousand lightning discharges showed that • Short wave radio emission of lightning consists of a series of short pulses with duration from less than 100 nanoseconds to several microseconds separated well longer gaps. • Background noise between lightning discharges is not differ from one observed without thunderstorm activity (at given sensitivity). Usually it is the same between lightning pulses at least at the initial stage. • Each lightning discharge radio emission starts with a number of very short (less than 100 nanoseconds at 0.7 level) bi-polar pulses. Gaps between initial pulses vary from several microseconds to few hundreds of microseconds. No radio emission was observed before the first pulse during at least 500 milliseconds. Both positive and negative polarity of the first pulses occur in approximately equal proportion in different lightning discharges while the polarity was the same in any individual lightning. • First pulse amplitude, width and waveform are consistent with predicted by the theory of combined action of runaway breakdown and extensive atmospheric shower caused by cosmic ray particle of 1016 eV energy. Lightning discharges at other planets can be initiated by cosmic ray particles as well. This work was partly supported by ISTC grant # 2236p. The work of one of the authors (A. N. Karashtin) was also partly supported by INTAS grant # 03-51-5727.

Variability in effective radiating area and output power of new ultrasound transducers at 3 MHz.

PubMed

Johns, Lennart D; Straub, Stephen J; Howard, Samuel M

2007-01-01

Spatial average intensity (SAI) is often used by clinicians to gauge therapeutic ultrasound dosage, yet SAI measures are not directly regulated by US Food and Drug Administration (FDA) standards. Current FDA guidelines permit a possible 50% to 150% minimum to maximum range of SAI values, potentially contributing to variability in clinical outcomes. To measure clinical values that describe ultrasound transducers and to determine the degree of intramanufacturer and intermanufacturer variability in effective radiating area, power, and SAI when the transducer is functioning at 3 MHz. A descriptive and interferential approach was taken to this quasi-experimental design. Measurement laboratory. Sixty-six 5-cm(2) ultrasound transducers were purchased from 6 different manufacturers. All transducers were calibrated and then assessed using standardized measurement techniques; SAI was normalized to account for variability in effective radiating area, resulting in an nSAI. Effective radiating area, power, and nSAI. All manufacturers with the exception of Omnisound (P = .534) showed a difference between the reported and measured effective radiating area values (P < .001). All transducers were within FDA guidelines for power (+/-20%). Chattanooga (0.85 +/- 0.05 W/cm(2)) had a lower nSAI (P < .05) than all other manufacturers functioning at 3 MHz. Intramanufacturer variability in SAI ranged from 16% to 35%, and intermanufacturer variability ranged from 22% to 61%. Clinicians should consider treatment values of each individual transducer, regardless of the manufacturer. In addition, clinicians should scrutinize the power calibration and recalibration record of the transducer and adjust clinical settings as needed for the desired level of heating. Our data may aid in explaining the reported heating differences among transducers from different manufacturers. Stricter FDA standards regarding effective radiating area and total power are needed, and standards regulating SAI should be

Variability in Effective Radiating Area and Output Power of New Ultrasound Transducers at 3 MHz

PubMed Central

Johns, Lennart D; Straub, Stephen J; Howard, Samuel M

2007-01-01

Context: Spatial average intensity (SAI) is often used by clinicians to gauge therapeutic ultrasound dosage, yet SAI measures are not directly regulated by US Food and Drug Administration (FDA) standards. Current FDA guidelines permit a possible 50% to 150% minimum to maximum range of SAI values, potentially contributing to variability in clinical outcomes. Objective: To measure clinical values that describe ultrasound transducers and to determine the degree of intramanufacturer and intermanufacturer variability in effective radiating area, power, and SAI when the transducer is functioning at 3 MHz. Design: A descriptive and interferential approach was taken to this quasi-experimental design. Setting: Measurement laboratory. Patients or Other Participants: Sixty-six 5-cm2 ultrasound transducers were purchased from 6 different manufacturers. Intervention(s): All transducers were calibrated and then assessed using standardized measurement techniques; SAI was normalized to account for variability in effective radiating area, resulting in an nSAI. Main Outcome Measure(s): Effective radiating area, power, and nSAI. Results: All manufacturers with the exception of Omnisound (P = .534) showed a difference between the reported and measured effective radiating area values (P < .001). All transducers were within FDA guidelines for power (±20%). Chattanooga (0.85 ± 0.05 W/cm2) had a lower nSAI (P < .05) than all other manufacturers functioning at 3 MHz. Intramanufacturer variability in SAI ranged from 16% to 35%, and intermanufacturer variability ranged from 22% to 61%. Conclusions: Clinicians should consider treatment values of each individual transducer, regardless of the manufacturer. In addition, clinicians should scrutinize the power calibration and recalibration record of the transducer and adjust clinical settings as needed for the desired level of heating. Our data may aid in explaining the reported heating differences among transducers from different manufacturers

1800 MHz in vitro exposure device for experimental studies on the effects of mobile communication systems.

PubMed

Ardoino, L; Lopresto, V; Mancini, S; Pinto, R; Lovisolo, G A

2004-01-01

A wire patch cell (WPC) operating at the uplink frequency band of GSM 1800 MHz has been designed for in vitro experiments with the aim of investigating the possible biological effects of electromagnetic radiation associated with cellular phones. The 1800 MHz WPC design is a direct descendant of the original 900 MHz WPC introduced by Laval et al. This system provides a homogeneous specific absorption rate distribution, using four 3.5 cm petri dishes simultaneously. Numerical dosimetry has been performed using a commercial code (CST Microwave Studio), in order to evaluate accurately the efficiency of the structure (in terms of W kg(-1) per 1 W input power) and the distribution in the chosen biological target. The numerical results have been confirmed by experimental measurements performed by measuring thermal increase due to a high power impulse. The efficiency of the structure is 1.25 +/- 25% W kg(-1) per 1 W input power higher than the efficiency of the 900 MHz WPC. A few adjustments have been made in order to use the WPC in a standard incubator and to avoid thermal increases related to the radio frequency exposure. This exposure system has been adopted for the experiments scheduled in the RAMP and GUARD projects (VFPE).

Exposure to 915 MHz radiation induces micronuclei in Vicia faba root tips.

PubMed

Gustavino, Bianca; Carboni, Giovanni; Petrillo, Roberto; Paoluzzi, Giovanni; Santovetti, Emanuele; Rizzoni, Marco

2016-03-01

The increasing use of mobile phones and wireless networks raised a great debate about the real carcinogenic potential of radiofrequency-electromagnetic field (RF-EMF) exposure associated with these devices. Conflicting results are reported by the great majority of in vivo and in vitro studies on the capability of RF-EMF exposure to induce DNA damage and mutations in mammalian systems. Aimed at understanding whether less ambiguous responses to RF-EMF exposure might be evidenced in plant systems with respect to mammalian ones, in the present work the mutagenic effect of RF-EMF has been studied through the micronucleus (MN) test in secondary roots of Vicia faba seedlings exposed to mobile phone transmission in controlled conditions, inside a transverse electro magnetic (TEM) cell. Exposure of roots was carried out for 72h using a continuous wave (CW) of 915 MHz radiation at three values of equivalent plane wave power densities (23, 35 and 46W/m(2)). The specific absorption rate (SAR) was measured with a calorimetric method and the corresponding values were found to fall in the range of 0.4-1.5W/kg. Results of three independent experiments show the induction of a significant increase of MN frequency after exposure, ranging from a 2.3-fold increase above the sham value, at the lowest SAR level, up to a 7-fold increase at the highest SAR. These findings are in agreement with the limited number of data on cytogenetic effects detected in other plant systems exposed to mobile phone RF-EMF frequencies and clearly show the capability of radiofrequency exposure to induce DNA damage in this eukaryotic cell system. © The Author 2015. Published by Oxford University Press on behalf of the UK Environmental Mutagen Society. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Spectropolarimetric Observations of Solar Noise Storms at Low Frequencies

NASA Astrophysics Data System (ADS)

Mugundhan, V.; Ramesh, R.; Kathiravan, C.; Gireesh, G. V. S.; Hegde, Aathira

2018-03-01

A new high-resolution radio spectropolarimeter instrument operating in the frequency range of 15 - 85 MHz has recently been commissioned at the Radio Astronomy Field Station of the Indian Institute of Astrophysics at Gauribidanur, 100 km north of Bangalore, India. We describe the design and construction of this instrument. We present observations of a solar radio noise storm associated with Active Region (AR) 12567 in the frequency range of {≈} 15 - 85 MHz during 18 and 19 July 2016, observed using this instrument in the meridian-transit mode. This is the first report that we are aware of in which both the burst and continuum properties are derived simultaneously. Spectral indices and degree of polarization of both the continuum radiation and bursts are estimated. It is found that i) Type I storm bursts have a spectral index of {≈} {+}3.5, ii) the spectral index of the background continuum is ≈+2.9, iii) the transition frequency between Type I and Type III storms occurs at ≈55 MHz, iv) Type III bursts have an average spectral index of ≈-2.7, v) the spectral index of the Type III continuum is ≈-1.6, and vi) the degree of circular polarization of all Type I (Type III) bursts is ≈90% (30%). The results obtained here indicate that the continuum emission is due to bursts occurring in rapid succession. We find that the derived parameters for Type I bursts are consistent with suprathermal electron acceleration theory and those of Type III favor fundamental plasma emission.

Bubble-based acoustic radiation force using chirp insonation to reduce standing wave effects.

PubMed

Erpelding, Todd N; Hollman, Kyle W; O'Donnell, Matthew

2007-02-01

Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young's modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200 and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size.

Vector similariton erbium-doped all-fiber laser generating sub-100-fs nJ pulses at 100 MHz.

PubMed

Olivier, Michel; Piché, Michel

2016-02-08

Erbium-doped mode-locked fiber lasers with repetition rates comparable to those of solid-state lasers and generating nJ pulses are required for many applications. Our goal was to design a fiber laser that would meet such requirements, that could be built at relatively low cost and that would be reliable and robust. We thus developed a high-fundamental-repetition-rate erbium-doped all-fiber laser operating in the amplifier similariton regime. Experimental characterization shows that this laser, which is mode-locked by nonlinear polarization evolution, emits 76-fs pulses with an energy of 1.17 nJ at a repetition rate of 100 MHz. Numerical simulations support the interpretation of self-similar evolution of the pulse in the gain fiber. More specifically we introduce the concept of vector similariton in fiber lasers. The coupled x- and y- polarization components of such a pulse have a pulse profile with a linear chirp and their combined power profile evolves self-similarly when the nonlinear asymptotic regime is reached in the gain fiber.

A 200 MHz surface acoustic wave mass microbalance

NASA Technical Reports Server (NTRS)

Bowers, William D.; Chuan, Raymond L.

1990-01-01

The principle of operation of the surface acoustic wave (SAW) piezoelectric crystals used as microgravimetric sensors in mass microbalances is discussed. Special attention is given to a SAW 200-MHz crystal developed for measuring molecular deposition on spacecrafts, whose operating frequency does not depend on the thickness of the crystal. The frequency stability of the 200 MHz SAW device is better than 5 x 10 exp -9, which corresponds to a lower limit-of-detection of 3 x 10 exp -12 g for a signal-to-noise ratio of 3. A block diagram of the 200 MHz SAW mass microbalance and a schematic diagram of SAW resonator are presented together with performance data of this device.

A search for ultrahigh-energy neutrinos and measurement of cosmic ray radio emission with the Antarctic Impulsive Transient Antenna

NASA Astrophysics Data System (ADS)

Hoover, Stephen Lam Douglas

2010-11-01

New astronomical messengers may reveal unexpected aspects of the Universe and have often provided a unique source of fresh physical insights. Neutrinos are a promising new messenger particle, capable of carrying information from otherwise inaccessible sources. The ANtarctic Impulsive Transient Antenna (ANITA) seeks to make the first detection of an ultrahigh-energy (E > 1018 eV) neutrino flux. Such a neutrino flux almost certainly exists, produced in interactions of ultrahigh-energy cosmic rays with photons from the cosmic microwave background. ANITA is a balloon payload which monitors large volumes of the Antarctic ice sheet from an altitude of 38 km. An ultrahigh-energy neutrino which interacts in the ice sheet will produce a particle shower which will coherently radiate Cherenkov radiation in radio wavelengths (<3 GHz). Antennas on the balloon payload can then detect the resulting impulsive radio signal. The full ANITA flew for the first time from 15 December 2006 to 19 January 2007. In this dissertation, I will describe the ground calibration system used to transmit calibration signals to the payload in-flight. I will then describe techniques for analysis of ANITA data and give limits on the ultrahigh-energy neutrino flux implied by the null result of that analysis. Finally, I will demonstrate that ANITA is also sensitive to ultrahigh-energy cosmic rays and show the detection of 16 ultrahigh-energy cosmic-ray events during ANITA's first flight. This constitutes the highest frequency and widest bandwidth radio observations of cosmic-ray emission to date I show the average waveform and spectrum of these events and describe their polarization properties, which are strongly correlated with the geomagnetic field.

Design and performance of an ultra-wideband stepped-frequency radar with precise frequency control for landmine and IED detection

NASA Astrophysics Data System (ADS)

Phelan, Brian R.; Sherbondy, Kelly D.; Ranney, Kenneth I.; Narayanan, Ram M.

2014-05-01

The Army Research Laboratory (ARL) has developed an impulse-based vehicle-mounted forward-looking ultra- wideband (UWB) radar for imaging buried landmines and improvised explosive devices (IEDs). However, there is no control of the radiated spectrum in this system. As part of ARL's Partnerships in Research Transition (PIRT) program, the above deficiency is addressed by the design of a Stepped-Frequency Radar (SFR) which allows for precise control over the radiated spectrum, while still maintaining an effective ultra-wide bandwidth. The SFR utilizes a frequency synthesizer which can be configured to excise prohibited and interfering frequency bands and also implement frequency-hopping capabilities. The SFR is designed to be a forward-looking ground- penetrating (FLGPR) Radar utilizing a uniform linear array of sixteen (16) Vivaldi notch receive antennas and two (2) Quad-ridge horn transmit antennas. While a preliminary SFR consisting of four (4) receive channels has been designed, this paper describes major improvements to the system, and an analysis of expected system performance. The 4-channel system will be used to validate the SFR design which will eventually be augmented in to the full 16-channel system. The SFR has an operating frequency band which ranges from 300 - 2000 MHz, and a minimum frequency step-size of 1 MHz. The radar system is capable of illuminating range swaths that have maximum extents of 30 to 150 meters (programmable). The transmitter has the ability to produce approximately -2 dBm/MHz average power over the entire operating frequency range. The SFR will be used to determine the practicality of detecting and classifying buried and concealed landmines and IEDs from safe stand-off distances.

Analysis of emotionality and locomotion in radio-frequency electromagnetic radiation exposed rats.

PubMed

Narayanan, Sareesh Naduvil; Kumar, Raju Suresh; Paval, Jaijesh; Kedage, Vivekananda; Bhat, M Shankaranarayana; Nayak, Satheesha; Bhat, P Gopalakrishna

2013-07-01

In the current study the modulatory role of mobile phone radio-frequency electromagnetic radiation (RF-EMR) on emotionality and locomotion was evaluated in adolescent rats. Male albino Wistar rats (6-8 weeks old) were randomly assigned into the following groups having 12 animals in each group. Group I (Control): they remained in the home cage throughout the experimental period. Group II (Sham exposed): they were exposed to mobile phone in switch-off mode for 28 days, and Group III (RF-EMR exposed): they were exposed to RF-EMR (900 MHz) from an active GSM (Global system for mobile communications) mobile phone with a peak power density of 146.60 μW/cm(2) for 28 days. On 29th day, the animals were tested for emotionality and locomotion. Elevated plus maze (EPM) test revealed that, percentage of entries into the open arm, percentage of time spent on the open arm and distance travelled on the open arm were significantly reduced in the RF-EMR exposed rats. Rearing frequency and grooming frequency were also decreased in the RF-EMR exposed rats. Defecation boli count during the EPM test was more with the RF-EMR group. No statistically significant difference was found in total distance travelled, total arm entries, percentage of closed arm entries and parallelism index in the RF-EMR exposed rats compared to controls. Results indicate that mobile phone radiation could affect the emotionality of rats without affecting the general locomotion.

High spectral purity Kerr frequency comb radio frequency photonic oscillator

PubMed Central

Liang, W.; Eliyahu, D.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

2015-01-01

Femtosecond laser-based generation of radio frequency signals has produced astonishing improvements in achievable spectral purity, one of the basic features characterizing the performance of an radio frequency oscillator. Kerr frequency combs hold promise for transforming these lab-scale oscillators to chip-scale level. In this work we demonstrate a miniature 10 GHz radio frequency photonic oscillator characterized with phase noise better than −60 dBc Hz−1 at 10 Hz, −90 dBc Hz−1 at 100 Hz and −170 dBc Hz−1 at 10 MHz. The frequency stability of this device, as represented by Allan deviation measurements, is at the level of 10−10 at 1–100 s integration time—orders of magnitude better than existing radio frequency photonic devices of similar size, weight and power consumption. PMID:26260955

Single Pixel Characterization of X-Ray TES Microcalorimeter Under AC Bias at MHz Frequencies

NASA Technical Reports Server (NTRS)

Gottardi, L.; Blandler, S. R.; Porter, F. S.; Sadleir, J. E.; Kilbourne, C. A.; Bailey, C. N.; Finkbeiner, F. M.; Chervenak, J. A.; Adams, J. S.; Eckart, M. E.;

A Hybrid Solution for Simultaneous Transfer of Ultrastable Optical Frequency, RF Frequency, and UTC Time-Tags Over Optical Fiber.

PubMed

Krehlik, Przemyslaw; Schnatz, Harald; Sliwczynski, Lukasz

2017-12-01

We describe a fiber-optic solution for simultaneous distribution of all signals generated at today's most advanced time and frequency laboratories, i.e., an ultrastable optical reference frequency derived from an optical atomic clock, a radio frequency precisely linked to a realization of the SI-Second, and a realization of an atomic timescale, being the local representation of the virtual, global UTC timescale. In our solution both the phase of the optical carrier and the delay of electrical signals (10-MHz frequency reference and one-pulse-per-second time tags) are stabilized against environmental perturbations influencing the fiber link instability and accuracy. We experimentally demonstrate optical transfer stabilities of and for 100 s averaging period, for optical carrier and 10-MHz signals, respectively.

Effect of laser intensity on radio frequency emissions from laser induced breakdown of atmospheric air

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

Vinoth Kumar, L.; Manikanta, E.; Leela, Ch.

2016-06-07

The studies on the effect of input laser intensity, through the variation of laser focusing geometry, on radio frequency (RF) emissions, over 30–1000 MHz from nanosecond (ns) and picosecond (ps) laser induced breakdown (LIB) of atmospheric air are presented. The RF emissions from the ns and ps LIB were observed to be decreasing and increasing, respectively, when traversed from tight to loose focusing conditions. The angular and radial intensities of the RF emissions from the ns and ps LIB are found to be consistent with sin{sup 2}θ/r{sup 2} dependence of the electric dipole radiation. The normalized RF emissions were observed tomore » vary with incident laser intensity (Iλ{sup 2}), indicating the increase in the induced dipole moment at moderate input laser intensities and the damping of radiation due to higher recombination rate of plasma at higher input laser intensities.« less

Frequency variations of the earth's obliquity and the 100-kyr ice-age cycles

NASA Technical Reports Server (NTRS)

Liu, Han-Shou

1992-01-01

Changes in the earth's climate are induced by variations in the earth's orbital parameters which modulate the seasonal distribution of solar radiation. Periodicities in the geological climate record with cycles of 100, 41, and 23 kyr have been linked with changes in obliquity, eccentricity, and precession of the equinoxes. The effect of variations of eccentricity during a 100 kyr period is weak relative to the signals from obliquity and precession variations and it may therefore be expected that the 100 kyr signal in the climate record would be of low intensity. However, this signal dominates the climate record and internal nonlinear processes within the climate system have previously been proposed to account for this fact. The author shows that variations in the frequency of the obliquity cycle can give rise to strong 100-kyr forcing of climate.

Distributing Frequency And Time Signals On Optical Fibers

NASA Technical Reports Server (NTRS)

Lutes, George F.

1993-01-01

Paper reports progress in distribution of frequency and time reference signals over optical fibers. Describes current performance at frequencies of 100 MHz, 1 GHz, and 8.4 GHz. Also describes transmitting and receiving equipment and discusses tradeoff between cost and performance. Concludes with discussion of likely future development and effects of developments on systems using distributed frequency reference signals.

Design Method For Ultra-High Resolution Linear CCD Imagers

NASA Astrophysics Data System (ADS)

Sheu, Larry S.; Truong, Thanh; Yuzuki, Larry; Elhatem, Abdul; Kadekodi, Narayan

1984-11-01

This paper presents the design method to achieve ultra-high resolution linear imagers. This method utilizes advanced design rules and novel staggered bilinear photo sensor arrays with quadrilinear shift registers. Design constraint in the detector arrays and shift registers are analyzed. Imager architecture to achieve ultra-high resolution is presented. The characteristics of MTF, aliasing, speed, transfer efficiency and fine photolithography requirements associated with this architecture are also discussed. A CCD imager with advanced 1.5 um minimum feature size was fabricated. It is intended as a test vehicle for the next generation small sampling pitch ultra-high resolution CCD imager. Standard double-poly, two-phase shift registers were fabricated at an 8 um pitch using the advanced design rules. A special process step that blocked the source-drain implant from the shift register area was invented. This guaranteed excellent performance of the shift registers regardless of the small poly overlaps. A charge transfer efficiency of better than 0.99995 and maximum transfer speed of 8 MHz were achieved. The imager showed excellent performance. The dark current was less than 0.2 mV/ms, saturation 250 mV, adjacent photoresponse non-uniformity ± 4% and responsivity 0.7 V/ μJ/cm2 for the 8 μm x 6 μm photosensor size. The MTF was 0.6 at 62.5 cycles/mm. These results confirm the feasibility of the next generation ultra-high resolution CCD imagers.

Contact resistance and overlapping capacitance in flexible sub-micron long oxide thin-film transistors for above 100 MHz operation

NASA Astrophysics Data System (ADS)

Münzenrieder, Niko; Salvatore, Giovanni A.; Petti, Luisa; Zysset, Christoph; Büthe, Lars; Vogt, Christian; Cantarella, Giuseppe; Tröster, Gerhard

2014-12-01

In recent years new forms of electronic devices such as electronic papers, flexible displays, epidermal sensors, and smart textiles have become reality. Thin-film transistors (TFTs) are the basic blocks of the circuits used in such devices and need to operate above 100 MHz to efficiently treat signals in RF systems and address pixels in high resolution displays. Beyond the choice of the semiconductor, i.e., silicon, graphene, organics, or amorphous oxides, the junctionless nature of TFTs and its geometry imply some limitations which become evident and important in devices with scaled channel length. Furthermore, the mechanical instability of flexible substrates limits the feature size of flexible TFTs. Contact resistance and overlapping capacitance are two parasitic effects which limit the transit frequency of transistors. They are often considered independent, while a deeper analysis of TFTs geometry imposes to handle them together; in fact, they both depend on the overlapping length (LOV) between source/drain and the gate contacts. Here, we conduct a quantitative analysis based on a large number of flexible ultra-scaled IGZO TFTs. Devices with three different values of overlap length and channel length down to 0.5 μm are fabricated to experimentally investigate the scaling behavior of the transit frequency. Contact resistance and overlapping capacitance depend in opposite ways on LOV. These findings establish routes for the optimization of the dimension of source/drain contact pads and suggest design guidelines to achieve megahertz operation in flexible IGZO TFTs and circuits.

Frequency dependence of tissue attenuation measured by acoustic microscopy.

PubMed

Daft, C M; Briggs, G A; O'Brien, W D

1989-05-01

Broadband scanning acoustic microscopy (SAM) has been used to investigate the mechanical properties of sections of tissue with a resolution of around 8 microns. The work reported here extends these results by reporting the frequency dependence of the attenuation coefficient from 100-500 MHz. A discussion of the theory of the measurements is presented. The scanning laser acoustic microscope (SLAM) is used to characterize similar tissue sections at 100 MHz. The data obtained with the two forms of acoustic microscopy are compared with results from the literature.

Gravitational Wave (GW) Classification, Space GW Detection Sensitivities and AMIGO (Astrodynamical Middle-frequency Interferometric GW Observatory)

NASA Astrophysics Data System (ADS)

Ni, Wei-Tou

2018-01-01

After first reviewing the gravitational wave (GW) spectral classification. we discuss the sensitivities of GW detection in space aimed at low frequency band (100 nHz-100 mHz) and middle frequency band (100 mHz-10 Hz). The science goals are to detect GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries; (v) Stellar-Size Black Hole Binaries; and (vi) Relic GW Background. The detector proposals have arm length ranging from 100 km to 1.35×109 km (9 AU) including (a) Solar orbiting detectors and (b) Earth orbiting detectors. We discuss especially the sensitivities in the frequency band 0.1-10 μHz and the middle frequency band (0.1 Hz-10 Hz). We propose and discuss AMIGO as an Astrodynamical Middlefrequency Interferometric GW Observatory.

The dielectric properties of human pineal gland tissue and RF absorption due to wireless communication devices in the frequency range 400-1850 MHz.

PubMed

Schmid, Gernot; Uberbacher, Richard; Samaras, Theodoros; Tschabitscher, Manfred; Mazal, Peter R

2007-09-07

In order to enable a detailed analysis of radio frequency (RF) absorption in the human pineal gland, the dielectric properties of a sample of 20 freshly removed pineal glands were measured less than 20 h after death. Furthermore, a corresponding high resolution numerical model of the brain region surrounding the pineal gland was developed, based on a real human tissue sample. After inserting this model into a commercially available numerical head model, FDTD-based computations for exposure scenarios with generic models of handheld devices operated close to the head in the frequency range 400-1850 MHz were carried out. For typical output power values of real handheld mobile communication devices, the obtained results showed only very small amounts of absorbed RF power in the pineal gland when compared to SAR limits according to international safety standards. The highest absorption was found for the 400 MHz irradiation. In this case the RF power absorbed inside the pineal gland (organ mass 96 mg) was as low as 11 microW, when considering a device of 500 mW output power operated close to the ear. For typical mobile phone frequencies (900 MHz and 1850 MHz) and output power values (250 mW and 125 mW) the corresponding values of absorbed RF power in the pineal gland were found to be lower by a factor of 4.2 and 36, respectively. These results indicate that temperature-related biologically relevant effects on the pineal gland induced by the RF emissions of typical handheld mobile communication devices are unlikely.

Ultrahigh Pressure Dynamic Compression

NASA Astrophysics Data System (ADS)

Duffy, T. S.

2017-12-01

Laser-based dynamic compression provides a new opportunity to study the lattice structure and other properties of geological materials to ultrahigh pressure conditions ranging from 100 - 1000 GPa (1 TPa) and beyond. Such studies have fundamental applications to understanding the Earth's core as well as the interior structure of super-Earths and giant planets. This talk will review recent dynamic compression experiments using high-powered lasers on materials including Fe-Si, MgO, and SiC. Experiments were conducted at the Omega laser (University of Rochester) and the Linac Coherent Light Source (LCLS, Stanford). At Omega, laser drives as large as 2 kJ are applied over 10 ns to samples that are 50 microns thick. At peak compression, the sample is probed with quasi-monochromatic X-rays from a laser-plasma source and diffraction is recorded on image plates. At LCLS, shock waves are driven into the sample using a 40-J laser with a 10-ns pulse. The sample is probed with X-rays form the LCLS free electron laser providing 1012 photons in a monochromatic pulse near 10 keV energy. Diffraction is recorded using pixel array detectors. By varying the delay between the laser and the x-ray beam, the sample can be probed at various times relative to the shock wave transiting the sample. By controlling the shape and duration of the incident laser pulse, either shock or ramp (shockless) loading can be produced. Ramp compression produces less heating than shock compression, allowing samples to be probed to ultrahigh pressures without melting. Results for iron alloys, oxides, and carbides provide new constraints on equations of state and phase transitions that are relevant to the interior structure of large, extrasolar terrestrial-type planets.

Frequency conversion of cw chemical HF laser radiation in nonlinear crystals

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

Klement'ev, V.M.; Kolpakov, Y.G.; Pecherskii, Y.Y.

1977-07-01

A description is given of a cw chemical HF laser and its characteristics. The results are reported of investigations of the efficiency of conversion of the HF laser radiation into second harmonics and combination frequencies in LiNbO/sub 3/, LiIO/sub 3/, and Ag/sub 3/AsS/sub 3/ crystals. The most efficient conversion was achieved in proustite (Ag/sub 3/AsS/sub 3/) when the second-harmonic power was approx.3..mu..W and the fundamental-frequency power was approx.100 mW. Twenty-one emission lines were obtained in the 1.39--1.49 ..mu.. range. The HF laser radiation was converted to the visible range (0.522--0.516 ..mu..).

A reconfigurable multi-mode multi-band transmitter with integrated frequency synthesizer for short-range wireless communication

NASA Astrophysics Data System (ADS)

Nan, Qi; Fan, Chen; Lingwei, Zhang; Xiaoman, Wang; Baoyong, Chi

2013-09-01

A reconfigurable multi-mode direct-conversion transmitter (TX) with integrated frequency synthesizer (FS) is presented. The TX as well as the FS is designed with a flexible architecture and frequency plan, which helps to support all the 433/868/915 MHz ISM band signals, with the reconfigurable bandwidth from 250 kHz to 2 MHz. In order to save power and chip area, only one 1.8 GHz VCO is adopted to cover the whole frequency range. All the operation modes can be regulated in real time by configuring the integrated register-bank through an SPI interface. Implemented in 180 nm CMOS, the FS achieves a frequency coverage of 320-460 MHz and 620-920 MHz. The lowest phase noise can be -107 dBc/Hz at a 100 kHz offset and -126 dBc/Hz at a 1 MHz offset. The transmitter features a + 10.2 dBm peak output power with a +9.5 dBm 1-dB-compression point and 250 kHz/500 kHz/1 MHz/2 MHz reconfigurable signal bandwidth.

Note: Fully integrated active quenching circuit achieving 100 MHz count rate with custom technology single photon avalanche diodes.

PubMed

Acconcia, G; Labanca, I; Rech, I; Gulinatti, A; Ghioni, M

2017-02-01

The minimization of Single Photon Avalanche Diodes (SPADs) dead time is a key factor to speed up photon counting and timing measurements. We present a fully integrated Active Quenching Circuit (AQC) able to provide a count rate as high as 100 MHz with custom technology SPAD detectors. The AQC can also operate the new red enhanced SPAD and provide the timing information with a timing jitter Full Width at Half Maximum (FWHM) as low as 160 ps.

Stable radio frequency dissemination by simple hybrid frequency modulation scheme.

PubMed

Yu, Longqiang; Wang, Rong; Lu, Lin; Zhu, Yong; Wu, Chuanxin; Zhang, Baofu; Wang, Peizhang

2014-09-15

In this Letter, we propose a fiber-based stable radio frequency transfer system by a hybrid frequency modulation scheme. Creatively, two radio frequency signals are combined and simultaneously transferred by only one laser diode. One frequency component is used to detect the phase fluctuation, and the other one is the derivative compensated signal providing a stable frequency for the remote end. A proper ratio of the frequencies of the components is well maintained by parameter m to avoid interference between them. Experimentally, a stable 200 MHz signal is transferred over 100 km optical fiber with the help of a 1 GHz detecting signal, and fractional instability of 2×10(-17) at 10(5) s is achieved.

Bubble-Based Acoustic Radiation Force Using Chirp Insonation to Reduce Standing Wave Effects

PubMed Central

Erpelding, Todd N.; Hollman, Kyle W.; O’Donnell, Matthew

2007-01-01

Bubble-based acoustic radiation force can measure local viscoelastic properties of tissue. High intensity acoustic waves applied to laser-generated bubbles induce displacements inversely proportional to local Young’s modulus. In certain instances, long pulse durations are desirable but are susceptible to standing wave artifacts, which corrupt displacement measurements. Chirp pulse acoustic radiation force was investigated as a method to reduce standing wave artifacts. Chirp pulses with linear frequency sweep magnitudes of 100, 200, and 300 kHz centered around 1.5 MHz were applied to glass beads within gelatin phantoms and laser-generated bubbles within porcine lenses. The ultrasound transducer was translated axially to vary standing wave conditions, while comparing displacements using chirp pulses and 1.5 MHz tone burst pulses of the same duration and peak rarefactional pressure. Results demonstrated significant reduction in standing wave effects using chirp pulses, with displacement proportional to acoustic intensity and bubble size. PMID:17306697

The effect of 2100 MHz radiofrequency radiation of a 3G mobile phone on the parotid gland of rats.

PubMed

Aydogan, Filiz; Unlu, Ilhan; Aydin, Emine; Yumusak, Nihat; Devrim, Erdinc; Samim, Ethem Erdal; Ozgur, Elcin; Unsal, Velid; Tomruk, Arin; Ozturk, Goknur Guler; Seyhan, Nesrin

2015-01-01

We aimed to evaluate the effect of 2100 MHz radiofrequency radiation on the parotid gland of rats in short and relatively long terms. Thirty Wistar albino rats were divided into four groups. Groups A and B served as the control groups (for 10 days and 40 days, respectively), and each group included six rats. Groups C and D were composed of nine rats each, and they were the exposure groups. The rats were exposed to 2100 MHz radiofrequency radiation emitted by a generator, simulating a third generation mobile phone for 6 hours/day, 5 days/week, for 10 or 40 days. Following exposure, the rats were sacrificed and parotid glands were removed. Histopathological and biochemical examinations were performed. Although there were no histopathological changes in the control groups except for two animals in group A and three animals in group B, the exposure groups C (10 days) and D (40 days) showed numerous histopathological changes regarding salivary gland damage including acinar epithelial cells, interstitial space, ductal system, vascular system, nucleus, amount of cytoplasm and variations in cell size. The histopathological changes were more prominent in group D compared to group C. There was statistically significant different parameter regarding variation in cell size between the groups B and D (p=0.036). The parotid gland of rats showed numerous histopathological changes after exposure to 2100 MHz radiofrequency radiation, both in the short and relatively long terms. Increased exposure duration led to an increase in the histopathological changes. Copyright © 2015 Elsevier Inc. All rights reserved.

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

MHz gravitational waves from short-term anisotropic inflation

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

Ito, Asuka; Soda, Jiro

2016-04-18

We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around 10{sup −26}∼10{sup −27} are copiously produced in high-frequency bands 10 MHz∼100 MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

Influence of Clay Content, Mineralogy and Fabric On Radar Frequency Response of Aquifer Materials

NASA Astrophysics Data System (ADS)

West, L. J.; Handley, K.

High frequency electromagnetic methods such as ground penetrating radar (GPR) and time domain reflectometry (TDR) are widely employed to measure water saturation in the vadose zone and water filled porosity in the saturated zone. However, previous work has shown that radar frequency dielectric properties are strongly influenced by clay as well as by water content. They have also shown that that the dielectric response of clay minerals is strongly frequency dependent, and that even a small proportion of clay such as that present in many sandstone aquifers can have a large effect at typi- cal GPR frequencies (around 100MHz). Hence accurate water content/porosity deter- mination requires clay type and content to be taken into account. Reported here are dielectric measurements on clay-sand mixtures, aimed at investigating the influence of clay mineralogy, particle shape, and the geometrical arrangement of the mixture constituents on GPR and TDR response. Dielectric permittivity (at 50-1000MHz) was measured for mixtures of Ottawa Sand and various clay minerals or clay size quartz rock flour, using a specially constructed dielectric cell. Both homogeneous and layered mixtures were tested. The influence of pore water salinity, clay type, and particle arrangement on the dielectric response is interpreted in terms of dielectric dispersion mechanisms. The appropriateness of var- ious dielectric mixing rules such as the Complex Refractive Index Method (CRIM) for determination of water content or porosity from field GPR and TDR data are dis- cussed.

Detection of Low Level Microwave Radiation Induced Deoxyribonucleic Acid Damage Vis-à-vis Genotoxicity in Brain of Fischer Rats

PubMed Central

Deshmukh, Pravin Suryakantrao; Megha, Kanu; Banerjee, Basu Dev; Ahmed, Rafat Sultana; Chandna, Sudhir; Abegaonkar, Mahesh Pandurang; Tripathi, Ashok Kumar

2013-01-01

Background: Non-ionizing radiofrequency radiation has been increasingly used in industry, commerce, medicine and especially in mobile phone technology and has become a matter of serious concern in present time. Objective: The present study was designed to investigate the possible deoxyribonucleic acid (DNA) damaging effects of low-level microwave radiation in brain of Fischer rats. Materials and Methods: Experiments were performed on male Fischer rats exposed to microwave radiation for 30 days at three different frequencies: 900, 1800 and 2450 MHz. Animals were divided into 4 groups: Group I (Sham exposed): Animals not exposed to microwave radiation but kept under same conditions as that of other groups, Group II: Animals exposed to microwave radiation at frequency 900 MHz at specific absorption rate (SAR) 5.953 × 10−4 W/kg, Group III: Animals exposed to 1800 MHz at SAR 5.835 × 10−4 W/kg and Group IV: Animals exposed to 2450 MHz at SAR 6.672 × 10−4 W/kg. At the end of the exposure period animals were sacrificed immediately and DNA damage in brain tissue was assessed using alkaline comet assay. Results: In the present study, we demonstrated DNA damaging effects of low level microwave radiation in brain. Conclusion: We concluded that low SAR microwave radiation exposure at these frequencies may induce DNA strand breaks in brain tissue. PMID:23833433

Effect of Low Level Subchronic Microwave Radiation on Rat Brain.

PubMed

Deshmukh, Pravin Suryakantrao; Megha, Kanu; Nasare, Namita; Banerjee, Basu Dev; Ahmed, Rafat Sultana; Abegaonkar, Mahesh Pandurang; Tripathi, Ashok Kumar; Mediratta, Pramod Kumari

2016-12-01

The present study was designed to investigate the effects of subchronic low level microwave radiation (MWR) on cognitive function, heat shock protein 70 (HSP70) level and DNA damage in brain of Fischer rats. Experiments were performed on male Fischer rats exposed to microwave radiation for 90 days at three different frequencies: 900, 1800, and 2450 MHz. Animals were divided into 4 groups: Group I: Sham exposed, Group II: animals exposed to microwave radiation at 900 MHz and specific absorption rate (SAR) 5.953 × 10-4 W/kg, Group III: animals exposed to 1800 MHz at SAR 5.835 × 10-4 W/kg and Group IV: animals exposed to 2450 MHz at SAR 6.672 × 10-4 W/kg. All the animals were tested for cognitive function using elevated plus maze and Morris water maze at the end of the exposure period and subsequently sacrificed to collect brain tissues. HSP70 levels were estimated by ELISA and DNA damage was assessed using alkaline comet assay. Microwave exposure at 900-2450 MHz with SAR values as mentioned above lead to decline in cognitive function, increase in HSP70 level and DNA damage in brain. The results of the present study suggest that low level microwave exposure at frequencies 900, 1800, and 2450 MHz may lead to hazardous effects on brain. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Real-time, ultrahigh-resolution, optical coherence tomography with an all-fiber, femtosecond fiber laser continuum at 1.5 microm.

PubMed

Nishizawa, N; Chen, Y; Hsiung, P; Ippen, E P; Fujimoto, J G

2004-12-15

Real-time, ultrahigh-resolution optical coherence tomography (OCT) is demonstrated in the 1.4-1.7-microm wavelength region with a stretched-pulse, passively mode-locked, Er-doped fiber laser and highly nonlinear fiber. The fiber laser generates 100-mW, linearly chirped pulses at a 51-MHz repetition rate. The pulses are compressed and then coupled into a normally dispersive highly nonlinear fiber to generate a low-noise supercontinuum with a 180-nm FWHM bandwidth and 38 mW of output power. This light source is stable, compact, and broadband, permitting high-speed, real-time, high-resolution OCT imaging. In vivo high-speed OCT imaging of human skin with approximately 5.5-microm resolution and 99-dB sensitivity is demonstrated.

A high-frequency transimpedance amplifier for CMOS integrated 2D CMUT array towards 3D ultrasound imaging.

PubMed

Huang, Xiwei; Cheong, Jia Hao; Cha, Hyouk-Kyu; Yu, Hongbin; Je, Minkyu; Yu, Hao

2013-01-01

One transimpedance amplifier based CMOS analog front-end (AFE) receiver is integrated with capacitive micromachined ultrasound transducers (CMUTs) towards high frequency 3D ultrasound imaging. Considering device specifications from CMUTs, the TIA is designed to amplify received signals from 17.5MHz to 52.5MHz with center frequency at 35MHz; and is fabricated in Global Foundry 0.18-µm 30-V high-voltage (HV) Bipolar/CMOS/DMOS (BCD) process. The measurement results show that the TIA with power-supply 6V can reach transimpedance gain of 61dBΩ and operating frequency from 17.5MHz to 100MHz. The measured input referred noise is 27.5pA/√Hz. Acoustic pulse-echo testing is conducted to demonstrate the receiving functionality of the designed 3D ultrasound imaging system.

Ruggedness testing and validation of a practical analytical method for > 100 veterinary drug residues in bovine muscle by ultrahigh performance liquid chromatography – tandem mass spectrometry

USDA-ARS?s Scientific Manuscript database

In this study, optimization, extension, and validation of a streamlined, qualitative and quantitative multiclass, multiresidue method was conducted to monitor great than100 veterinary drug residues in meat using ultrahigh-performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS). I...

The Importance of High Frequency Observations for the SKA

NASA Astrophysics Data System (ADS)

Welch, William J.

2007-12-01

The plan for the Square Kilometer Array (SKA) is one or more very large arrays operating in two or more contiguous frequency bands: roughly 15 - 90 MHz, 120 - 500 MHz, and 500 MHz - 25 GHz. The last band may be further divided into roughly 500 MHz - 1.5 GHz and 1.5 - 25 GHz. Construction costs may delay or forgo one or more of these bands. We argue that the entire high frequency band is of special importance for astronomy both in the local universe and at great distances and early times. One of the Key Science Projects, the Cradle of Life, requires high sensitivity and resolution at frequencies up to 20 GHz for the study of forming disks around new stars with disk opacities too great for millimeter wave observations. The larger issue of star formation, a poorly understood area, will also benefit from high sensitivity observations at short cm wavelengths. Magnetic field measurements through the Zeeman effect in the densest star forming gas are best done using tracers such as CCS at frequencies of 11 and 22 GHz. The wide frequency range of the SKA permits the observation of multiple rotational transitions of long chain molecules, providing accurate measures of both gas densities and temperatures. The wide field of view will permit large scale surveys of entire star forming clouds revealing, at high resolution, the formation of clusters of pre-protostellar stars and class 0-2 protostars in line radiation. The continuum cm wave radiation will reveal the growth of grains in disks. On the larger scale, observations of CO at high redshifts will trace the evolution of star formation and the formation of metals back to the Epic of Reionization.

LOFAR 150-MHz observations of SS 433 and W 50

NASA Astrophysics Data System (ADS)

Broderick, J. W.; Fender, R. P.; Miller-Jones, J. C. A.; Trushkin, S. A.; Stewart, A. J.; Anderson, G. E.; Staley, T. D.; Blundell, K. M.; Pietka, M.; Markoff, S.; Rowlinson, A.; Swinbank, J. D.; van der Horst, A. J.; Bell, M. E.; Breton, R. P.; Carbone, D.; Corbel, S.; Eislöffel, J.; Falcke, H.; Grießmeier, J.-M.; Hessels, J. W. T.; Kondratiev, V. I.; Law, C. J.; Molenaar, G. J.; Serylak, M.; Stappers, B. W.; van Leeuwen, J.; Wijers, R. A. M. J.; Wijnands, R.; Wise, M. W.; Zarka, P.

2018-04-01

We present Low-Frequency Array (LOFAR) high-band data over the frequency range 115-189 MHz for the X-ray binary SS 433, obtained in an observing campaign from 2013 February to 2014 May. Our results include a deep, wide-field map, allowing a detailed view of the surrounding supernova remnant W 50 at low radio frequencies, as well as a light curve for SS 433 determined from shorter monitoring runs. The complex morphology of W 50 is in excellent agreement with previously published higher frequency maps; we find additional evidence for a spectral turnover in the eastern wing, potentially due to foreground free-free absorption. Furthermore, SS 433 is tentatively variable at 150 MHz, with both a debiased modulation index of 11 per cent and a χ2 probability of a flat light curve of 8.2 × 10-3. By comparing the LOFAR flux densities with contemporaneous observations carried out at 4800 MHz with the RATAN-600 telescope, we suggest that an observed ˜0.5-1 Jy rise in the 150-MHz flux density may correspond to sustained flaring activity over a period of approximately 6 months at 4800 MHz. However, the increase is too large to be explained with a standard synchrotron bubble model. We also detect a wealth of structure along the nearby Galactic plane, including the most complete detection to date of the radio shell of the candidate supernova remnant G 38.7-1.4. This further demonstrates the potential of supernova remnant studies with the current generation of low-frequency radio telescopes.

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation

PubMed Central

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-01-01

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 106, which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results. PMID:26976363

Ultra-high dynamic range electro-optic sampling for detecting millimeter and sub-millimeter radiation.

PubMed

Ibrahim, Akram; Férachou, Denis; Sharma, Gargi; Singh, Kanwarpal; Kirouac-Turmel, Marie; Ozaki, Tsuneyuki

2016-03-15

Time-domain spectroscopy using coherent millimeter and sub-millimeter radiation (also known as terahertz radiation) is rapidly expanding its application, owing greatly to the remarkable advances in generating and detecting such radiation. However, many current techniques for coherent terahertz detection have limited dynamic range, thus making it difficult to perform some basic experiments that need to directly compare strong and weak terahertz signals. Here, we propose and demonstrate a novel technique based on cross-polarized spectral-domain interferometry to achieve ultra-high dynamic range electro-optic sampling measurement of coherent millimeter and sub-millimeter radiation. In our scheme, we exploit the birefringence in a single-mode polarization maintaining fiber in order to measure the phase change induced by the electric field of terahertz radiation in the detection crystal. With our new technique, we have achieved a dynamic range of 7 × 10(6), which is 4 orders of magnitude higher than conventional electro-optic sampling techniques, while maintaining comparable signal-to-noise ratio. The present technique is foreseen to have great impact on experiments such as linear terahertz spectroscopy of optically thick materials (such as aqueous samples) and nonlinear terahertz spectroscopy, where the higher dynamic range is crucial for proper interpretation of experimentally obtained results.

Exploratory Thermal-mechanical Fatigue Results for Rene' 80 in Ultrahigh Vacuum

NASA Technical Reports Server (NTRS)

Sheinker, A. A.

1978-01-01

A limited study was conducted of the use of strainage partitioning for predicting the thermalmechanical fatigue life of cast nickel-base superalloy Rene' 80. The fatigue lives obtained by combined inphase thermal and mechanical strain cycling between 400 C (752 F) and 1000 C (1802 F) in an ultrahigh vacuum were considerably shorter than those represented by the four basic partitioned inelastic strainrange fatigue life relationships established previously for this alloy at 871 C (1600 F) and 1000 C (1832 F) in an ultrahigh vacuum. This behavior was attributed to the drastic decrease in ductility with decreasing temperature for this alloy. These results indicated that the prediction of the thermal-mechanical fatigue life of Rene' 80 by the method of strainrange partioning may be improved if based on the four basic fatigue life relationships determined at a lower temperature in the thermal-mechanical strain cycle.

Design and analysis microstrip dipole using fractal Koch for 433 MHz applications

NASA Astrophysics Data System (ADS)

Zulfin, M.; Rambe, A. H.; Budi, B.

2018-02-01

This paper discussed the dipole microstrip antenna design using fractal Koch for working on frequency of 433 MHz. The fractal Koch was used to reduce the size of the microstrip antenna. The smaller the antenna size, the lighter the equipment. AWR simulator was employed to evaluate antenna parameters such as return loss, gain and radiation pattern. The antenna was designed on a FR4 substrate with relative permittivity of 4.4 and thickness 1.6 mm. The result shows that the fractal Koch reduce antenna size about 41.2% and decrease return loss about 30%.

Design of matching layers for high-frequency ultrasonic transducers

PubMed Central

Fei, Chunlong; Ma, Jianguo; Chiu, Chi Tat; Williams, Jay A.; Fong, Wayne; Chen, Zeyu; Zhu, BenPeng; Xiong, Rui; Shi, Jing; Hsiai, Tzung K.; Shung, K. Kirk; Zhou, Qifa

2015-01-01

Matching the acoustic impedance of high-frequency (≥100 MHz) ultrasound transducers to an aqueous loading medium remains a challenge for fabricating high-frequency transducers. The traditional matching layer design has been problematic to establish high matching performance given requirements on both specific acoustic impedance and precise thickness. Based on both mass-spring scheme and microwave matching network analysis, we interfaced metal-polymer layers for the matching effects. Both methods hold promises for guiding the metal-polymer matching layer design. A 100 MHz LiNbO3 transducer was fabricated to validate the performance of the both matching layer designs. In the pulse-echo experiment, the transducer echo amplitude increased by 84.4% and its −6dB bandwidth increased from 30.2% to 58.3% comparing to the non-matched condition, demonstrating that the matching layer design method is effective for developing high-frequency ultrasonic transducers. PMID:26445518

10 CFR 35.1000 - Other medical uses of byproduct material or radiation from byproduct material.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false Other medical uses of byproduct material or radiation from... MATERIAL Other Medical Uses of Byproduct Material or Radiation From Byproduct Material § 35.1000 Other medical uses of byproduct material or radiation from byproduct material. A licensee may use byproduct...

10 CFR 35.1000 - Other medical uses of byproduct material or radiation from byproduct material.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Other medical uses of byproduct material or radiation from... MATERIAL Other Medical Uses of Byproduct Material or Radiation From Byproduct Material § 35.1000 Other medical uses of byproduct material or radiation from byproduct material. A licensee may use byproduct...

10 CFR 35.1000 - Other medical uses of byproduct material or radiation from byproduct material.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Other medical uses of byproduct material or radiation from... MATERIAL Other Medical Uses of Byproduct Material or Radiation From Byproduct Material § 35.1000 Other medical uses of byproduct material or radiation from byproduct material. A licensee may use byproduct...

10 CFR 35.1000 - Other medical uses of byproduct material or radiation from byproduct material.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Other medical uses of byproduct material or radiation from... MATERIAL Other Medical Uses of Byproduct Material or Radiation From Byproduct Material § 35.1000 Other medical uses of byproduct material or radiation from byproduct material. A licensee may use byproduct...

10 CFR 35.1000 - Other medical uses of byproduct material or radiation from byproduct material.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Other medical uses of byproduct material or radiation from... MATERIAL Other Medical Uses of Byproduct Material or Radiation From Byproduct Material § 35.1000 Other medical uses of byproduct material or radiation from byproduct material. A licensee may use byproduct...

A 2-to-48-MHz Phase-Locked Loop

NASA Technical Reports Server (NTRS)

Koudelka, Robert D.

2004-01-01

A 2-to-48-MHz phase-locked loop (PLL), developed for the U.S. space program, meets or exceeds all space shuttle clock electrical interface requirements by taking as its reference a 2-to-48-MHz clock signal and outputting a phaselocked clock signal set at the same frequency as the reference clock with transistor- transistor logic (TTL) voltage levels. Because it is more adaptable than other PLLs, the new PLL can be used in industries that employ signaling devices and as a tool in future space missions. A conventional PLL consists of a phase/frequency detector, loop filter, and voltage-controlled oscillator in which each component exists individually and is integrated into a single device. PLL components phase-lock to a single frequency or to a narrow bandwidth of frequencies. It is this design, however, that prohibits them from maintaining phase lock to a dynamically changing reference clock when a large bandwidth is required a deficiency the new PLL overcomes. Since most PLL components require their voltage-controlled oscillators to operate at greater than 2-MHz frequencies, conventional PLLs often cannot achieve the low-frequency phase lock allowed by the new PLL. The 2-to-48-MHz PLL is built on a wire-wrap board with pins wired to three position jumpers; this makes changing configurations easy. It responds to variations in voltage-controlled oscillator (VCO) ranges, duty cycle, signal-to-noise ratio (SNR), amplitude, and jitter, exceeding design specifications. A consensus state machine, implemented in a VCO range detector which assures the PLL continues to operate in the correct range, is the primary control state machine for the 2-to-48-MHz PLL circuit. By using seven overlapping frequency ranges with hysteresis, the PLL output sets the resulting phase-locked clock signal at a frequency that agrees with the reference clock with TTL voltage levels. As a space-shuttle tool, the new PLL circuit takes the noisy, degraded reference clock signals as input and outputs

Tunable Heterodyne Receiver from 100 Micron to 1,000 Micron for Airborne Observations

NASA Technical Reports Server (NTRS)

Roeser, H. P.; Wattenbach, R.; Vanderwal, P.

1984-01-01

Interest in high resolution spectrometers for the submillimeter wavelength range from 100 micron to 1,000 micron is mostly stimulated by molecular spectroscopy in radioastronomy and atmospheric physics, and by plasma diagnostic experiments. Schottky diodes in waveguide mixer technology and InSb-hot electron bolometers are successfully used in the 0.5 to a few millimeter range whereas tandem Fabry-Perot spectrometers combined with photoconductive detectors (Ge:Sb and Ge:Ga) are used for the 100 micron range. Recent research on heterodyne spectrometers, with Schottky diodes in an open structure mixer and a molecular laser as local oscillators, which can be used over the whole wavelength range is summarized.

Examination of High Frequency MHz Rheology of Filled Polymer Composites and Photopolymers

NASA Astrophysics Data System (ADS)

Yeh, Chyi-Huey Joshua

The quartz crystal microbalance (QCM) is a versatile characterization tool capable of tracking changes in areal mass and high frequency MHz rheology of micron thick films. The QCM primarily consists of a single quartz disc with electrodes deposited on both sides of the disc. Due to the piezoelectric nature of quartz, introduction of an oscillating voltage near the resonance condition of the quartz disc produces a traveling shear wave that can be measured with electrical admittance analysis. This technique behaves like an acoustic reflectometer, where an induced mechanical shear wave propagates and reflects at the interfaces between material layers with differing acoustic impedances. Based on how the shear wave interacts with the interfaces, information on the material properties can be quantitatively modeled. In this dissertation, a quantitative approach of determining the magnitude and sources of error is presented, so that interpretation of viscoelastic information and areal mass changes can be performed with confidence. Specifically, the role of anharmonic coupling with harmonic modes are explored and simulated with COMSOL Multiphysics. Several case studies motivating and highlighting the utility of the QCM is presented. The fracture and thermal aging behavior of several nanofilled silicone elastomers are examined using traditional mechanical tests, such as pure shear geometry and dynamic mechanical analysis (DMA). Results can be qualitatively explained by the concept of dynamic mechanical heterogeneity, where a high mechanical contrast is desired for high fracture toughness. However, DMA results can be difficult to interpret (especially at shifted high frequencies) due to thermal rheological complexity, a characteristic commonly found in many polymer composites. This motivates the application of the QCM, where MHz viscoelastic behavior can be directly probed, providing insight on the dissipative behavior at local length scales. Investigation of polysilicate

Intravascular photoacoustic imaging at 35 and 80 MHz

PubMed Central

Li, Xiang; Wei, Wei; Shung, K. Kirk

2012-01-01

Abstract. The catheter-based intravascular photoacoustic (IVPA) imaging for diagnosing atherosclerosis, which can provide optical absorption contrast of the arterial wall besides acoustic scattering contrast from the conventional intravascular ultrasound (IVUS) imaging, has been intensively researched recently. The resolution of IVPA is determined by the frequency bandwidth of an ultrasonic transducer. Higher resolution can be achieved by increasing the transducer’s working frequency and bandwidth. We introduce IVPA imaging at 35 and 80 MHz by using newly designed integrated IVUS/IVPA probes. This is the first time IVPA has been achieved as high as 80 MHz. Six-micrometer tungsten wires were imaged to evaluate the probes’ spatial resolutions and beam patterns. Healthy rabbit aorta was imaged in vitro. Imaging results show that IVPA has superior contrast over IVUS in identifying the arterial wall, and IVPA at 80 MHz demonstrates extraordinary resolution (35 μm) compared to 35 MHz. PMID:23224004

High quality factor manganese-doped aluminum lumped-element kinetic inductance detectors sensitive to frequencies below 100 GHz

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

Jones, G.; Johnson, B. R.; Abitbol, M. H.

Aluminum lumped-element kinetic inductance detectors (LEKIDs) sensitive to millimeter-wave photons have been shown to exhibit high quality factors, making them highly sensitive and multiplexable. The superconducting gap of aluminum limits aluminum LEKIDs to photon frequencies above 100 GHz. Manganese-doped aluminum (Al-Mn) has a tunable critical temperature and could therefore be an attractive material for LEKIDs sensitive to frequencies below 100 GHz if the internal quality factor remains sufficiently high when manganese is added to the film. To investigate, we measured some of the key properties of Al-Mn LEKIDs. A prototype eight-element LEKID array was fabricated using a 40 nm thickmore » film of Al-Mn deposited on a 500 μm thick high-resistivity, float-zone silicon substrate. The manganese content was 900 ppm, the measured T c = 694 ± 1mK, and the resonance frequencies were near 150 MHz. Using measurements of the forward scattering parameter S 21 at various bath temperatures between 65 and 250 mK, we determined that the Al-Mn LEKIDs we fabricated have internal quality factors greater than 2 × 10 5, which is high enough for millimeter-wave astrophysical observations. In the dark conditions under which these devices were measured, the fractional frequency noise spectrum shows a shallow slope that depends on bath temperature and probe tone amplitude, which could be two-level system noise. In conclusion, the anticipated white photon noise should dominate this level of low-frequency noise when the detectors are illuminated with millimeter-waves in future measurements. The LEKIDs responded to light pulses from a 1550 nm light-emitting diode, and we used these light pulses to determine that the quasiparticle lifetime is 60 μs.« less

High quality factor manganese-doped aluminum lumped-element kinetic inductance detectors sensitive to frequencies below 100 GHz

DOE PAGES

Jones, G.; Johnson, B. R.; Abitbol, M. H.; ...

2017-05-29

Aluminum lumped-element kinetic inductance detectors (LEKIDs) sensitive to millimeter-wave photons have been shown to exhibit high quality factors, making them highly sensitive and multiplexable. The superconducting gap of aluminum limits aluminum LEKIDs to photon frequencies above 100 GHz. Manganese-doped aluminum (Al-Mn) has a tunable critical temperature and could therefore be an attractive material for LEKIDs sensitive to frequencies below 100 GHz if the internal quality factor remains sufficiently high when manganese is added to the film. To investigate, we measured some of the key properties of Al-Mn LEKIDs. A prototype eight-element LEKID array was fabricated using a 40 nm thickmore » film of Al-Mn deposited on a 500 μm thick high-resistivity, float-zone silicon substrate. The manganese content was 900 ppm, the measured T c = 694 ± 1mK, and the resonance frequencies were near 150 MHz. Using measurements of the forward scattering parameter S 21 at various bath temperatures between 65 and 250 mK, we determined that the Al-Mn LEKIDs we fabricated have internal quality factors greater than 2 × 10 5, which is high enough for millimeter-wave astrophysical observations. In the dark conditions under which these devices were measured, the fractional frequency noise spectrum shows a shallow slope that depends on bath temperature and probe tone amplitude, which could be two-level system noise. In conclusion, the anticipated white photon noise should dominate this level of low-frequency noise when the detectors are illuminated with millimeter-waves in future measurements. The LEKIDs responded to light pulses from a 1550 nm light-emitting diode, and we used these light pulses to determine that the quasiparticle lifetime is 60 μs.« less

Beam dynamics and electromagnetic studies of a 3 MeV, 325 MHz radio frequency quadrupole accelerator

NASA Astrophysics Data System (ADS)

Gaur, Rahul; Kumar, Vinit

2018-05-01

We present the beam dynamics and electromagnetic studies of a 3 MeV, 325 MHz H- radio frequency quadrupole (RFQ) accelerator for the proposed Indian Spallation Neutron Source project. We have followed a design approach, where the emittance growth and the losses are minimized by keeping the tune depression ratio larger than 0.5. The transverse cross-section of RFQ is designed at a frequency lower than the operating frequency, so that the tuners have their nominal position inside the RFQ cavity. This has resulted in an improvement of the tuning range, and the efficiency of tuners to correct the field errors in the RFQ. The vane-tip modulations have been modelled in CST-MWS code, and its effect on the field flatness and the resonant frequency has been studied. The deterioration in the field flatness due to vane-tip modulations is reduced to an acceptable level with the help of tuners. Details of the error study and the higher order mode study along with mode stabilization technique are also described in the paper.

Ultrahigh vacuum gauge having two collector electrodes

NASA Technical Reports Server (NTRS)

Torney, F. L., Jr. (Inventor)

1967-01-01

A gauge for measuring ultrahigh vacuums with great accuracy is described. It provides a means for ionizing the gas whose pressure is being measured, and consists of a collector electrode, a suppressor, radiation shielding, and a second collector.

Frequency comb based on a narrowband Yb-fiber oscillator: pre-chirp management for self-referenced carrier envelope offset frequency stabilization.

PubMed

Lim, Jinkang; Chen, Hung-Wen; Chang, Guoqing; Kärtner, Franz X

2013-02-25

Laser frequency combs are normally based on mode-locked oscillators emitting ultrashort pulses of ~100-fs or shorter. In this paper, we present a self-referenced frequency comb based on a narrowband (5-nm bandwidth corresponding to 415-fs transform-limited pulses) Yb-fiber oscillator with a repetition rate of 280 MHz. We employ a nonlinear Yb-fiber amplifier to both amplify the narrowband pulses and broaden their optical spectrum. To optimize the carrier envelope offset frequency (fCEO), we optimize the nonlinear pulse amplification by pre-chirping the pulses at the amplifier input. An optimum negative pre-chirp exists, which produces a signal-to-noise ratio of 35 dB (100 kHz resolution bandwidth) for the detected fCEO. We phase stabilize the fCEO using a feed-forward method, resulting in 0.64-rad (integrated from 1 Hz to 10 MHz) phase noise for the in-loop error signal. This work demonstrates the feasibility of implementing frequency combs from a narrowband oscillator, which is of particular importance for realizing large line-spacing frequency combs based on multi-GHz oscillators usually emitting long (>200 fs) pulses.

A 140 GHz Pulsed EPR/212 MHz NMR Spectrometer for DNP Studies

PubMed Central

Smith, Albert A.; Corzilius, Björn; Bryant, Jeffrey A.; DeRocher, Ronald; Woskov, Paul P.; Temkin, Richard J.; Griffin, Robert G.

2012-01-01

We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz (1H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE011 resonator acts as both an NMR coil and microwave resonator, and a double balanced (1H, 13C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = ½ electron spins, 100 kHz on 1H, and 50 kHz on 13C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (>3 T). PMID:22975246

A 140 GHz pulsed EPR/212 MHz NMR spectrometer for DNP studies

NASA Astrophysics Data System (ADS)

Smith, Albert A.; Corzilius, Björn; Bryant, Jeffrey A.; DeRocher, Ronald; Woskov, Paul P.; Temkin, Richard J.; Griffin, Robert G.

2012-10-01

We described a versatile spectrometer designed for the study of dynamic nuclear polarization (DNP) at low temperatures and high fields. The instrument functions both as an NMR spectrometer operating at 212 MHz (1H frequency) with DNP capabilities, and as a pulsed-EPR operating at 140 GHz. A coiled TE011 resonator acts as both an NMR coil and microwave resonator, and a double balanced (1H, 13C) radio frequency circuit greatly stabilizes the NMR performance. A new 140 GHz microwave bridge has also been developed, which utilizes a four-phase network and ELDOR channel at 8.75 GHz, that is then multiplied and mixed to obtain 140 GHz microwave pulses with an output power of 120 mW. Nutation frequencies obtained are as follows: 6 MHz on S = 1/2 electron spins, 100 kHz on 1H, and 50 kHz on 13C. We demonstrate basic EPR, ELDOR, ENDOR, and DNP experiments here. Our solid effect DNP results demonstrate an enhancement of 144 and sensitivity gain of 310 using OX063 trityl at 80 K and an enhancement of 157 and maximum sensitivity gain of 234 using Gd-DOTA at 20 K, which is significantly better performance than previously reported at high fields (⩾3 T).

Radiative Instabilities in Three-Dimensional Astrophysical Masers

NASA Technical Reports Server (NTRS)

Scappaticci, Gerardo A.; Watson, William D.

1995-01-01

Inherent instabilities in the radiative transfer for astrophysical masers have been recognized and calculated in the linear maser idealization in our previous investigations. The same instabilities are now shown to occur in the more realistic, three-dimensional geometries. Fluctuations in the emergent flux result and may be related to the observed fluctuations in the radiative flux from the 1665 MHz OH masers that have been reported to occur on timescales as short as 1000 s. The time-dependent differential equations of radiative transfer are solved numerically for three-dimensional astrophysical masers. Computations are performed for spherical and elongated (rectangular parallelepiped) geometries.

Synchrotron Spectral Curvature from 22 MHZ to 23 GHZ

NASA Technical Reports Server (NTRS)

Kogut, Alan J.

2012-01-01

We combine surveys of the radio sky at frequencies 22 MHz to 1.4 GHz with data from the ARCADE-2 instrument at frequencies 3 GHz to 10 GHz to characterize the frequency spectrum of diffuse synchrotron emission in the Galaxy. The radio spectrum steepens with frequency from 22 MHz to 10 GHz. The projected spectral index at 23 GHz derived from the low-frequency data agrees well with independent measurements using only data at frequencies 23 GHz and above. Comparing the spectral index at 23 GHz to the value from previously published analyses allows extension of the model to higher frequencies. The combined data are consistent with a power-law index beta = -2.64 +/-= 0.03 at 0.31 GHz, steepening by an amount of Delta-beta = 0.07 every octave in frequency. Comparison of the radio data to models including the cosmic-ray energy spectrum suggests that any break in the synchrotron spectrum must occur at frequencies above 23 GHz.

Supernova dynamics in the laboratory: Radiative shocks produced by ultra-high pressure implosion experiments on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Pak, Arthur

2012-10-01

Thermonuclear fuel experiments on the National Ignition Facility implode 2-mm diameter capsules with a cryogenic deuterium-tritium ice layer to 1000x liquid density and pressures exceeding 100 Gbar (10^11 atm). About 200 ps after peak compression, a spherical supernova-like radiative shock wave is observed that expands with shock velocities of uS = 300 km/s, temperatures of order 1 keV at densities of 1 g/cc resulting in a radiation strength parameter of Q ˜uS^5 = 10^4. Radiation-hydrodynamic simulations indicate that the shock launched at stagnation first goes down a strong density gradient while propagating outward from the highly compressed DT fuel (˜ 1000g/cc) to the ablation front (˜ 1 g/cc). Similar to what happens inside a star, the shock pressure drops as it accelerates and heats. The radiative shock emission is first observed when it breaks out of the dense compressed fuel shell into the low-density inflowing plasma at the ablation front mimicking the supernova situation where the shock breaks out through the star surface into surrounding in-falling matter [1,2]; the shock is subsequently approaching the supercritical state with a strong pre-cursor followed by rapid cooling. These observations are consistent with the rapid vanishing of the radiation ring 400 ps after peak compression due to strong radiation losses and spherical expansion. The evolution and brightness of the radiative shock provides insight into the performance of these implosions that have the goal to produce burning fusion plasmas in the laboratory. By modifying the capsule ablator composition and thickness, the stagnation pressure, density gradients, shock velocity and radiative properties could be tailored to study various regimes related to supernovae radiative remnants.[4pt] [1] W. David Arnett, Supernovae as phenomena of high-energy astrophysics, Ann NY Aca. Science 302, 90 (1977).[0pt] [2] L. Ensman and A. Burrows, Shock breakout in SN1987A, ApJ 393, 742.

Total absorption and photoionization cross sections of water vapor between 100 and 1000 A

NASA Technical Reports Server (NTRS)

Haddad, G. N.; Samson, J. A. R.

1986-01-01

Absolute photoabsorption and photoionization cross sections of water vapor are reported at a large number of discrete wavelengths between 100 and 1000 A with an estimate error of + or - 3 percent in regions free from any discrete structure. The double ionization chamber technique utilized is described. Recent calculations are shown to be in reasonable agreement with the present data.

CPW-fed Circularly Polarized Slot Antenna with Small Gap and Stick-shaped Shorted Strip for UHF FRID Readers

NASA Astrophysics Data System (ADS)

Pan, Chien-Yuan; Su, Chum-Chieh; Yang, Wei-Lin

2018-04-01

A new circularly polarized (CP) slot antenna with a small gap and a stick-shaped shorted strip is presented. The proposed antenna has a sufficient bandwidth for ultrahigh frequency (UHF) radio-frequency identification (RFID) reader applications. The antenna structure consists of a rectangular slot with a small gap, a stick-shaped shorted strip and a 50 Ω coplanar waveguide (CPW) feedline with an asymmetrical ground plane. By using the stick -shaped shorted strip to disturb magnetic current distribution on the slot, the CP radiation can be generated. The measured results demonstrate that the proposed antenna can reach a 10 dB return loss impedance bandwidth of 14.1 % (894-1030 MHz) and a 3 dB axial ratio (AR) bandwidth of 6.4 % (910-970 MHz). The whole antenna size is 80 × 80 × 1.6 mm3.

High-frequency phase shift measurement greatly enhances the sensitivity of QCM immunosensors.

PubMed

March, Carmen; García, José V; Sánchez, Ángel; Arnau, Antonio; Jiménez, Yolanda; García, Pablo; Manclús, Juan J; Montoya, Ángel

2015-03-15

In spite of being widely used for in liquid biosensing applications, sensitivity improvement of conventional (5-20MHz) quartz crystal microbalance (QCM) sensors remains an unsolved challenging task. With the help of a new electronic characterization approach based on phase change measurements at a constant fixed frequency, a highly sensitive and versatile high fundamental frequency (HFF) QCM immunosensor has successfully been developed and tested for its use in pesticide (carbaryl and thiabendazole) analysis. The analytical performance of several immunosensors was compared in competitive immunoassays taking carbaryl insecticide as the model analyte. The highest sensitivity was exhibited by the 100MHz HFF-QCM carbaryl immunosensor. When results were compared with those reported for 9MHz QCM, analytical parameters clearly showed an improvement of one order of magnitude for sensitivity (estimated as the I50 value) and two orders of magnitude for the limit of detection (LOD): 30μgl(-1) vs 0.66μgL(-1)I50 value and 11μgL(-1) vs 0.14μgL(-1) LOD, for 9 and 100MHz, respectively. For the fungicide thiabendazole, I50 value was roughly the same as that previously reported for SPR under the same biochemical conditions, whereas LOD improved by a factor of 2. The analytical performance achieved by high frequency QCM immunosensors surpassed those of conventional QCM and SPR, closely approaching the most sensitive ELISAs. The developed 100MHz QCM immunosensor strongly improves sensitivity in biosensing, and therefore can be considered as a very promising new analytical tool for in liquid applications where highly sensitive detection is required. Copyright © 2014 Elsevier B.V. All rights reserved.

Thermal and physiologic responses to 1200-MHz radiofrequency radiation: Differences between exposure in E and H orientation

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

Jauchem, J.R.; Frei, M.R.; Padilla, J.M.

1990-09-01

Ketamine-anesthetized Sprague-Dawley rats were exposed to far-field 1200-MHz continuous wave radiofrequency radiation in both E and H orientations (long axis of animal parallel to electric or magnetic field, respectively). Power densities were used that resulted in equivalent whole-body specific absorption rates of approximately 8 W/kg in both orientations (20 mW/cm{sup 2} for E and 45 mW/cm{sup 2} for H). Exposure was conducted to repeatedly increase colonic temperature from 38.5 to 39.5{degrees}C in both orientations in the same animal. Irradiation in E orientation resulted in greater colonic, tympanic, left subcutaneous (side toward antenna), and tail heating. The results indicated a moremore » uniform distribution of heat than that which occurred in previous experiments of 2450-MHz irradiation in E and H orientation. A lack of significant differences in blood pressure and heart rate responses between exposures in the two orientations in this study suggest that greater peripheral heating, as was seen in the earlier study of 2450 MHz, is necessary for these differences to occur.« less

Real-Time, Polyphase-FFT, 640-MHz Spectrum Analyzer

NASA Technical Reports Server (NTRS)

Zimmerman, George A.; Garyantes, Michael F.; Grimm, Michael J.; Charny, Bentsian; Brown, Randy D.; Wilck, Helmut C.

1994-01-01

Real-time polyphase-fast-Fourier-transform, polyphase-FFT, spectrum analyzer designed to aid in detection of multigigahertz radio signals in two 320-MHz-wide polarization channels. Spectrum analyzer divides total spectrum of 640 MHz into 33,554,432 frequency channels of about 20 Hz each. Size and cost of polyphase-coefficient memory substantially reduced and much of processing loss of windowed FFTs eliminated.

High-power, continuous-wave, solid-state, single-frequency, tunable source for the ultraviolet.

PubMed

Aadhi, A; Apurv Chaitanya, N; Singh, R P; Samanta, G K

2014-06-15

We report the development of a compact, high-power, continuous-wave, single-frequency, ultraviolet (UV) source with extended wavelength tunability. The device is based on single-pass, intracavity, second-harmonic-generation (SHG) of the signal radiation of a singly resonant optical parametric oscillator (SRO) working in the visible and near-IR wavelength range. The SRO is pumped in the green with a 25-mm-long, multigrating, MgO doped periodically poled stoichiometric lithium tantalate (MgO:sPPLT) as nonlinear crystal. Using three grating periods, 8.5, 9.0, and 9.5 μm of the MgO:sPPLT crystal and a single set of cavity mirrors, the SRO can be tuned continuously across 710.7-836.3 nm in the signal and corresponding idler across 2115.8-1462.1 nm with maximum idler power of 1.9 W and maximum out-coupled signal power of 254 mW. By frequency-doubling the intracavity signal with a 5-mm-long bismuth borate (BIBO) crystal, we can further tune the SRO continuously over 62.8 nm across 355.4-418.2 nm in the UV with maximum single-frequency UV power, as much as 770 mW at 398.28 nm in a Gaussian beam profile. The UV radiation has an instantaneous line-width of ∼14.5  MHz and peak-peak frequency stability of 151 MHz over 100 s. More than 95% of the tuning range provides UV power >260  mW. Access to lower UV wavelengths can in principle be realized by operating the SRO in the visible using shorter grating periods.

High frequency electromagnetic impedance measurements for characterization, monitoring and verification efforts. 1998 annual progress report

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

Lee, K.H.; Pellerin, L.; Becker, A.

1998-06-01

'Non-invasive, high-resolution imaging of the shallow subsurface is needed for delineation of buried waste, detection of unexploded ordinance, verification and monitoring of containment structures, and other environmental applications. Electromagnetic measurements at frequencies between 1 and 100 MHz are important for such applications, because the induction number of many targets is small due, and the ability to determine the dielectric permittivity in addition to electrical conductivity of the subsurface is possible. Earlier workers were successful in developing systems for detecting anomalous areas, but no quantifiable information was accurately determined. For high resolution imaging, accurate measurements are necessary so the field datamore » can be mapped into the space of the subsurface parameters. The authors are developing a non-invasive method for accurately imaging the electrical conductivity and dielectric permittivity of the shallow subsurface using the plane wave impedance approach, known as the magnetotelluric (MT) method at low frequencies. Electric and magnetic sensors are being tested in a known area against theoretical predictions, thereby insuring that the data collected with the high-frequency impedance (HFI) system will support high-resolution, multi-dimensional imaging techniques. The summary of the work to date is divided into three sections: equipment procurement, instrumentation, and theoretical developments. For most earth materials, the frequency range from 1 to 100 MHz encompasses a very difficult transition zone between the wave propagation of displacement currents and the diffusive behavior of conduction currents. Test equipment, such as signal generators and amplifiers, does not cover the entire range except at great expense. Hence the authors have divided the range of investigation into three sub-ranges: 1--10 MHz, 10--30 MHz, and 30--100 MHz. Results to date are in the lowest frequency range of 1--10 MHz. Even though conduction

A Simple Semaphore Signaling Technique for Ultra-High Frequency Spacecraft Communications

NASA Technical Reports Server (NTRS)

Butman, S.; Satorius, E.; Ilott, P.

2005-01-01

For planetary lander missions such as the upcoming Phoenix mission to Mars, the most challenging phase of the spacecraft-to-ground communications is during the critical phase termed entry, descent, and landing (EDL). At 8.4 GHz (X-band), the signals received by the largest Deep Space Network (DSN) antennas can be too weak for even 1 bit per second (bps) and therefore not able to communicate critical information to Earth. Fortunately, the lander s ultra-high frequency (UHF) link to an orbiting relay can meet the EDL requirements, but the data rate needs to be low enough to fit the capability of the UHF link during some or all of EDL. On Phoenix, the minimum data rate of the as-built UHF radio is 8 kbps and requires a signal level at the Odyssey orbiter of at least -120 dBm. For lower signaling levels, the effective data rate needs to be reduced, but without incurring the cost of rebuilding and requalifying the equipment. To address this scenario, a simple form of frequency-shift keying (FSK) has been devised by appropriately programming the data stream that is input to the UHF transceiver. This article describes this technique and provides performance estimates. Laboratory testing reveals that input signal levels at -140 dBm and lower can routinely be demodulated with the proposed signaling scheme, thereby providing a 20-dB and greater margin over the 8-kbps threshold.

A Simple Semaphore Signaling Technique for Ultra-High Frequency Spacecraft Communications

NASA Astrophysics Data System (ADS)

Butman, S.; Satorius, E.; Illott, P.

2005-11-01

For planetary lander missions such as the upcoming Phoenix mission to Mars, the most challenging phase of the spacecraft-to-ground communications is during the critical phase termed entry, descent, and landing (EDL). At 8.4 GHz (X-band), the signals received by the largest Deep Space Network (DSN) antennas can be too weak for even 1 bit per second (bps) and therefore not able to communicate critical information to Earth. Fortunately, the lander's ultra-high frequency (UHF) link to an orbiting relay can meet the EDL requirements, but the data rate needs to be low enough to fit the capability of the UHF link during some or all of EDL. On Phoenix, the minimum data rate of the as-built UHF radio is 8 kbps and requires a signal level at the Odyssey orbiter of at least minus 120 dBm. For lower signaling levels, the effective data rate needs to be reduced, but without incurring the cost of rebuilding and requalifying the equipment. To address this scenario, a simple form of frequency-shift keying (FSK) has been devised by appropriately programming the data stream that is input to the UHF transceiver. This article describes this technique and provides performance estimates. Laboratory testing reveals that input signal levels at minus 140 dBm and lower can routinely be demodulated with the proposed signaling scheme, thereby providing a 20-dB and greater margin over the 8-kbps threshold.

Non-thermal continuous and modulated electromagnetic radiation fields effects on sleep EEG of rats☆

PubMed Central

Mohammed, Haitham S.; Fahmy, Heba M.; Radwan, Nasr M.; Elsayed, Anwar A.

2012-01-01

In the present study, the alteration in the sleep EEG in rats due to chronic exposure to low-level non-thermal electromagnetic radiation was investigated. Two types of radiation fields were used; 900 MHz unmodulated wave and 900 MHz modulated at 8 and 16 Hz waves. Animals has exposed to radiation fields for 1 month (1 h/day). EEG power spectral analyses of exposed and control animals during slow wave sleep (SWS) and rapid eye movement sleep (REM sleep) revealed that the REM sleep is more susceptible to modulated radiofrequency radiation fields (RFR) than the SWS. The latency of REM sleep increased due to radiation exposure indicating a change in the ultradian rhythm of normal sleep cycles. The cumulative and irreversible effect of radiation exposure was proposed and the interaction of the extremely low frequency radiation with the similar EEG frequencies was suggested. PMID:25685416

77 FR 19575 - Promoting Interoperability in the 700 MHz Commercial Spectrum; Interoperability of Mobile User...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-02

... this document. FOR FURTHER INFORMATION CONTACT: Brenda Boykin, Wireless Telecommunications Bureau, (202... power levels of up to 1000 kW.\\2\\ The Lower A Block is also adjacent to the unpaired Lower 700 MHz E Block, where licensees (along with Lower 700 MHz D Block licensees) may operate at power levels up to 50...

Features of behavior of the plasma area formed by explosion spent in range of heights of 100-1000 km

NASA Astrophysics Data System (ADS)

Vasilev, Mikhail; Kholodov, Alexander; Stupitsky, Evgeny; Repin, Andrew

Explosive plasma experiments remain the important means of research of geophysical effects in the top ionosphere and magnetosphere. In particular their results can be useful for development of full model of powerful geomagnetic storms. Scientific and applied value of such experiments depends on our ability to simulate them numerically and to understand the physical processes. Complexity of mathematical modelling of such experiments is caused by two circumstances - complexity and variety of physical processes, and large-scale three-dimensional current of plasma. It's important to note that not all features of the processes under consideration are well known and well modelled. And plasma parameters in the indignant area can vary up to 5-7 orders. During last several years we have developed universal enough 3D algorithm for the simulation of large-scale movement of the plasma, based on MHD approach. Diffusion of a magnetic field and the ionization structure of plasma and air is considered. The full algorithm includes the most initial the radiation-gas dynamic stage, a stage of inertial scattering when the charging structure of plasma is formed, a stage of braking of plasma a geomagnetic field and the rarefied ionosphere and later (down to 100-500 s) the stage of convective movements of plasma in a geomagnetic field and the rarefied ionosphere. The algorithm is based on special updating of a monotonous conservative variant of grid-characteristic method 2-3 orders of the approximation, including splitting on spatial variables. Calculations of explosion of energy about 1015 J are executed for some heights from a range of 100-1000 km. Character of development of current essentially varies depending on height. For 100-120 km current is close to bi-dimensional, in an initial stage the shock wave is formed, and for the period of 40-60 seconds the plasma area rises up to 300 km. At heights more than 150 km current, for a while more than 5 seconds are got with character of a

Results from a MHz gravitational wave search using the Fermilab Holometer

NASA Astrophysics Data System (ADS)

Kamai, Brittany; Holometer Collaboration Collaboration

2017-01-01

The Fermilab Holometer, two nested 40 meter Michelson interferometers, has extended the accessible gravitational wave frequency range from kHz to a broad range of MHz frequencies. I will present results from a 130-hr campaign that measured the energy density of gravitational waves in the MHz band. Additionally, this dataset was used to place constraints on the abundance of primordial black hole binaries.

Mitigating intrinsic defects and laser damage using pulsetrain-burst (>100 MHz) ultrafast laser processing

NASA Astrophysics Data System (ADS)

McKinney, Luke; Frank, Felix; Graper, David; Dean, Jesse; Forrester, Paul; Rioblanc, Maxence; Nantel, Marc; Marjoribanks, Robin

2005-09-01

Ultrafast-laser micromachining has promise as an approach to trimming and 'healing' small laser-produced damage sites in laser-system optics--a common experience in state-of-the-art high-power laser systems. More-conventional approaches currently include mechanical micromachining, chemical modification, and treatment using cw and long-pulse lasers. Laser-optics materials of interest include fused silica, multilayer dielectric stacks for anti-reflection coatings or high-reflectivity mirrors, and inorganic crystals such as KD*P, used for Pockels cells and frequency-doubling. We report on novel efforts using ultrafast-laser pulsetrain-burst processing (microsecond bursts at 133 MHz) to mitigate damage in fused silica, dielectric coatings, and KD*P crystals. We have established the characteristics of pulsetrain-burst micromachining in fused silica, multilayer mirrors, and KD*P, and determined the etch rates and morphology under different conditions of fluence-delivery. From all of these, we have begun to identify new means to optimize the laser-repair of optics defects and damage.

Base-Level Guide for Electromagnetic Frequency Radiation

DTIC Science & Technology

2012-12-01

hazards of EMF-producing systems and equipment, e.g., hazard of electromagnetic radiation to ordnance (HERO), and hazard ...AFRL-SA-WP-SR-2013-0003 BASE-LEVEL GUIDE FOR ELECTROMAGNETIC FREQUENCY RADIATION Matthew W. Uelen Battelle Memorial Institute...COVERED (From – To) Dec 2011 – Dec 2012 4. TITLE AND SUBTITLE Base-Level Guide for Electromagnetic Frequency Radiation 5a. CONTRACT NUMBER

Programmable 10 MHz optical fiducial system for hydrodiagnostic cameras

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

Huen, T.

1987-07-01

A solid state light control system was designed and fabricated for use with hydrodiagnostic streak cameras of the electro-optic type. With its use, the film containing the streak images will have on it two time scales simultaneously exposed with the signal. This allows timing and cross timing. The latter is achieved with exposure modulation marking onto the time tick marks. The purpose of using two time scales will be discussed. The design is based on a microcomputer, resulting in a compact and easy to use instrument. The light source is a small red light emitting diode. Time marking can bemore » programmed in steps of 0.1 microseconds, with a range of 255 steps. The time accuracy is based on a precision 100 MHz quartz crystal, giving a divided down 10 MHz system frequency. The light is guided by two small 100 micron diameter optical fibers, which facilitates light coupling onto the input slit of an electro-optic streak camera. Three distinct groups of exposure modulation of the time tick marks can be independently set anywhere onto the streak duration. This system has been successfully used in Fabry-Perot laser velocimeters for over four years in our Laboratory. The microcomputer control section is also being used in providing optical fids to mechanical rotor cameras.« less

47 CFR 101.147 - Frequency assignments.

Code of Federal Regulations, 2013 CFR

2013-10-01

... video entertainment material to the licensee's customers. (30) The frequency band 18,580-19,300 GHz is... 18,820-18,870 MHz and 19,160-19,210 MHz. (31) This frequency band can be used for Multichannel Video... MHz (17) 941.0-941.5 MHz (27) 941.5-944 MHz (17) (18) 952.0-960.0 MHz (28) 1,850-1,990 MHz (20) (22) 2...

47 CFR 101.147 - Frequency assignments.

Code of Federal Regulations, 2014 CFR

2014-10-01

... video entertainment material to the licensee's customers. (30) The frequency band 18,580-19,300 GHz is... 18,820-18,870 MHz and 19,160-19,210 MHz. (31) This frequency band can be used for Multichannel Video... MHz (17) 941.0-941.5 MHz (27) 941.5-944 MHz (17) (18) 952.0-960.0 MHz (28) 1,850-1,990 MHz (20) (22) 2...

Lithographed Superconducting Resonator Development for Next-Generation Frequency Multiplexing Readout of Transition-Edge Sensors

NASA Astrophysics Data System (ADS)

Faramarzi, F.; De Haan, T.; Kusaka, A.; Lee, A.; Neuhauser, B.; Plambeck, R.; Raum, C.; Suzuki, A.; Westbrook, B.

2018-03-01

Ground-based cosmic microwave background (CMB) experiments are undergoing a period of exponential growth. Current experiments are observing with 1000-10,000 detectors, and the next-generation experiment (CMB stage 4) is proposing to deploy approximately 500,000 detectors. This order of magnitude increase in detector count will require a new approach for readout electronics. We have developed superconducting resonators for next-generation frequency-domain multiplexing (fMUX) readout architecture. Our goal is to reduce the physical size of resonators, such that resonators and detectors can eventually be integrated on a single wafer. To reduce the size of these resonators, we have designed spiral inductors and interdigitated capacitors that resonate around 10-100 MHz, an order of magnitude higher frequency compared to current fMUX readout systems. The higher frequency leads to a wider bandwidth and would enable higher multiplexing factor than the current ˜ 50 detectors per readout channel. We will report on the simulation, fabrication method, characterization technique, and measurement of quality factor of these resonators.

Oxidative changes and apoptosis induced by 1800-MHz electromagnetic radiation in NIH/3T3 cells.

PubMed

Hou, Qingxia; Wang, Minglian; Wu, Shuicai; Ma, Xuemei; An, Guangzhou; Liu, Huan; Xie, Fei

2015-03-01

To investigate the potential adverse effects of mobile phone radiation, we studied reactive oxygen species (ROS), DNA damage and apoptosis in mouse embryonic fibroblasts (NIH/3T3) after intermittent exposure (5 min on/10 min off, for various durations from 0.5 to 8 h) to an 1800-MHz GSM-talk mode electromagnetic radiation (EMR) at an average specific absorption rate of 2 W/kg. A 2',7'-dichlorofluorescin diacetate fluorescence probe was used to detect intracellular ROS levels, immunofluorescence was used to detect γH2AX foci as a marker for DNA damage, and flow cytometry was used to measure apoptosis. Our results showed a significant increase in intracellular ROS levels after EMR exposure and it reached the highest level at an exposure time of 1 h (p < 0.05) followed by a slight decrease when the exposure continued for as long as 8 h. No significant effect on the number of γH2AX was detected after EMR exposure. The percentage of late-apoptotic cells in the EMR-exposed group was significantly higher than that in the sham-exposed groups (p < 0.05). These results indicate that an 1800-MHz EMR enhances ROS formation and promotes apoptosis in NIH/3T3 cells.

Asymptotically zero power charge-recycling bus architecture for battery-operated ultrahigh data rate ULSI's

NASA Astrophysics Data System (ADS)

Yamauchi, Hiroyuki; Akamatsu, Hironori; Fujita, Tsutomu

1995-04-01

An asymptotically zero power charge recycling bus (CRB) architecture, featuring virtual stacking of the individual bus-capacitance into a series configuration between supply voltage and ground, has been proposed. This CRB architecture makes it possible to reduce not only each bus-swing but also a total equivalent bus-capacitance of the ultramultibit buses running in parallel. The voltage swing of each bus is given by the recycled charge-supplying from the upper adjacent bus capacitance, instead of the power line. The dramatical power reduction was verified by the simulated and measured data. According to these data, the ultrahigh data rate of 25.6 Gb/s can be achieved while maintaining the power dissipation to be less than 100 mW, which corresponds to less than 10% that of the previously reported 0.9 V suppressed bus-swing scheme, at V(sub cc) = 3.6 V for the bus width of 512 b with the bus-capacitance of 14 pF per bit operating at 50 MHz.

Pilot Search for 54-MHz Maser Emission from Interstellar Hydroxyl Using LOFAR

NASA Astrophysics Data System (ADS)

Hoffman, Ian M.; Heald, G.; Oonk, R.; McKean, J.; Mol, J.; Hessels, J.; Toribio, C.; LOFAR Collaboration

2014-01-01

We present the results of the most sensitive search to date for the two 54-MHz spectral lines of the hydroxyl (OH) molecule. These are the preliminary results of a larger, planned observational campaign. The splitting of the rotational ground state of the hydroxyl molecule gives rise to the four familiar 1.7-GHz transitions by which OH is known in the interstellar medium. There are also two magnetic-dipole transitions among these states at frequencies of 53.2 MHz and 55.1 MHz. These 54-MHz transitions have never been detected astronomically. Because of the relative weakness of the magnetic-dipole emission process, it is expected that only maser emission will generate a detectable 54-MHz signal. Two previous searches have been conducted by other authors with other instruments toward Galactic sources of known 1720-MHz OH maser emission: three sources were searched at 55.1 MHz and two other sources were searched at 53.2 MHz, resulting in upper limits of approximately 30 Jy for spectral channels of 2 km/s in width. In preparation for our future observational campaign that will apply the unprecedented sensitivity of LOFAR to the search for 54-MHz OH emission, we conducted a pilot project using six hours of Commissioning Time. These observations employed 21 48-element stations and produced a spectral resolution of approximately 0.5 km/s for both the 53.2- and 55.1-MHz lines. This spectral resolution is a considerable improvement over previous searches since it is suitable both for resolving the characteristically narrow width of maser lines and for identifying radiofrequency interference. In our pilot observations, no emission was detected at either frequency with an upper limit of approximately 3 Jy. We observed the Galactic sources W75N and W3(OH), neither of which have been searched previously at either frequency. We discuss the astrophysical implications of these sensitive non-detections. LOFAR, the Low Frequency Array designed and constructed by ASTRON, has

Effect of 935-MHz phone-simulating electromagnetic radiation on endometrial glandular cells during mouse embryo implantation.

PubMed

Liu, Wenhui; Zheng, Xinmin; Qu, Zaiqing; Zhang, Ming; Zhou, Chun; Ma, Ling; Zhang, Yuanzhen

2012-10-01

This study examined the impact of 935MHz phone-simulating electromagnetic radiation on embryo implantation of pregnant mice. Each 7-week-old Kunming (KM) female white mouse was set up with a KM male mouse in a single cage for mating overnight after induction of ovulation. In the first three days of pregnancy, the pregnant mice was exposed to electromagnetic radiation at low-intensity (150 μW/cm(2), ranging from 130 to 200 μW/cm(2), for 2- or 4-h exposure every day), mid-intensity (570 μW/cm(2), ranging from 400 to 700 μW/cm(2), for 2- or 4-h exposure every day) or high-intensity (1400 μW/cm(2), ranging from 1200 to 1500 μW/cm(2), for 2- or 4-h exposure every day), respectively. On the day 4 after gestation (known as the window of murine embryo implantation), the endometrium was collected and the suspension of endometrial glandular cells was made. Laser scanning microscopy was employed to detect the mitochondrial membrane potential and intracellular calcium ion concentration. In high-intensity, 2- and 4-h groups, mitochondrial membrane potential of endometrial glandular cells was significantly lower than that in the normal control group (P<0.05). The calcium ion concentration was increased in low-intensity 2-h group but decreased in high-intensity 4-h group as compared with the normal control group (P<0.05). However, no significant difference was found in mitochondrial membrane potential of endometrial glandular cells between low- or mid-intensity groups and the normal control group, indicating stronger intensity of the electromagnetic radiation and longer length of the radiation are required to inflict a remarkable functional and structural damage to mitochondrial membrane. Our data demonstrated that electromagnetic radiation with a 935-MHz phone for 4 h conspicuously decreased mitochondrial membrane potential and lowered the calcium ion concentration of endometrial glandular cells. It is suggested that high-intensity electromagnetic radiation is very likely

47 CFR 27.303 - Upper 700 MHz commercial and public safety coordination zone.

Code of Federal Regulations, 2011 CFR

2011-10-01

... safety coordinator. (1) The description must include, at a minimum; (i) The frequency or frequencies on... 47 Telecommunication 2 2011-10-01 2011-10-01 false Upper 700 MHz commercial and public safety... Rules for WCS § 27.303 Upper 700 MHz commercial and public safety coordination zone. (a) General. CMRS...

High Resolution Frequency Measurements of Far-Infrared Laser Lines

DTIC Science & Technology

2010-04-01

1 High Resolution Frequency Measurements of Far-Infrared Laser Lines Elizabeth J. Ehasz, Thomas M. Goyette, Robert H. Giles and William E. Nixon...Abstract—The frequency of four previously reported far- infrared laser lines have been measured to an accuracy of 100 kHz. These laser lines were measured ... frequencies measured here and the listed frequencies for these laser lines ranged from 59 MHz to 3.9 GHz. Index Terms—FIR Laser, Gas Laser, Molecular

935 MHz cellular phone radiation. An in vitro study of genotoxicity in human lymphocytes.

PubMed

Stronati, L; Testa, A; Moquet, J; Edwards, A; Cordelli, E; Villani, P; Marino, C; Fresegna, A M; Appolloni, M; Lloyd, D

2006-05-01

The possibility of genotoxicity of radiofrequency radiation (RFR) applied alone or in combination with x-rays was investigated in vitro using several assays on human lymphocytes. The chosen specific absorption rate (SAR) values are near the upper limit of actual energy absorption in localized tissue when persons use some cellular telephones. The purpose of the combined exposures was to examine whether RFR might act epigenetically by reducing the fidelity of repair of DNA damage caused by a well-characterized and established mutagen. Blood specimens from 14 donors were exposed continuously for 24 h to a Global System for Mobile Communications (GSM) basic 935 MHz signal. The signal was applied at two SAR; 1 and 2 W/Kg, alone or combined with a 1-min exposure to 1.0 Gy of 250 kVp x-rays given immediately before or after the RFR. The assays employed were the alkaline comet technique to detect DNA strand breakage, metaphase analyses to detect unstable chromosomal aberrations and sister chromatid exchanges, micronuclei in cytokinesis-blocked binucleate lymphocytes and the nuclear division index to detect alterations in the speed of in vitro cell cycling. By comparison with appropriate sham-exposed and control samples, no effect of RFR alone could be found for any of the assay endpoints. In addition RFR did not modify any measured effects of the x-radiation. This study has used several standard in vitro tests for chromosomal and DNA damage in Go human lymphocytes exposed in vitro to a combination of x-rays and RFR. It has comprehensively examined whether a 24-h continuous exposure to a 935 MHz GSM basic signal delivering SAR of 1 or 2 W/Kg is genotoxic per se or whether, it can influence the genotoxicity of the well-established clastogenic agent; x-radiation. Within the experimental parameters of the study in all instances no effect from the RFR signal was observed.

The Astronomical Low-Frequency Array

NASA Technical Reports Server (NTRS)

Jones, D. L.; Allen, R. J.; Blume, W. H.; Desch, M. M.; Erickson, W. C.; Kaiser, M. L.; Kassim, N. E.; Kuiper, T. B. H.; Mahoney, M. J.; Marsh, K. A.;

Frequency band adjustment match filtering based on variable frequency GPR antennas pairing scheme for shallow subsurface investigations

NASA Astrophysics Data System (ADS)

Shaikh, Shahid Ali; Tian, Gang; Shi, Zhanjie; Zhao, Wenke; Junejo, S. A.

2018-02-01

Ground penetrating Radar (GPR) is an efficient tool for subsurface geophysical investigations, particularly at shallow depths. The non-destructiveness, cost efficiency, and data reliability are the important factors that make it an ideal tool for the shallow subsurface investigations. Present study encompasses; variations in central frequency of transmitting and receiving GPR antennas (Tx-Rx) have been analyzed and frequency band adjustment match filters are fabricated and tested accordingly. Normally, the frequency of both the antennas remains similar to each other whereas in this study we have experimentally changed the frequencies of Tx-Rx and deduce the response. Instead of normally adopted three pairs, a total of nine Tx-Rx pairs were made from 50 MHz, 100 MHz, and 200 MHz antennas. The experimental data was acquired at the designated near surface geophysics test site of the Zhejiang University, Hangzhou, China. After the impulse response analysis of acquired data through conventional as well as varied Tx-Rx pairs, different swap effects were observed. The frequency band and exploration depth are influenced by transmitting frequencies rather than the receiving frequencies. The impact of receiving frequencies was noticed on the resolution; the more noises were observed using the combination of high frequency transmitting with respect to low frequency receiving. On the basis of above said variable results we have fabricated two frequency band adjustment match filters, the constant frequency transmitting (CFT) and the variable frequency transmitting (VFT) frequency band adjustment match filters. By the principle, the lower and higher frequency components were matched and then incorporated with intermediate one. Therefore, this study reveals that a Tx-Rx combination of low frequency transmitting with high frequency receiving is a better choice. Moreover, both the filters provide better radargram than raw one, the result of VFT frequency band adjustment filter is

Evaluating the More Suitable ISM Frequency Band for IoT-Based Smart Grids: A Quantitative Study of 915 MHz vs. 2400 MHz.

PubMed

Sandoval, Ruben M; Garcia-Sanchez, Antonio-Javier; Garcia-Sanchez, Felipe; Garcia-Haro, Joan

2016-12-31

IoT has begun to be employed pervasively in industrial environments and critical infrastructures thanks to its positive impact on performance and efficiency. Among these environments, the Smart Grid (SG) excels as the perfect host for this technology, mainly due to its potential to become the motor of the rest of electrically-dependent infrastructures. To make this SG-oriented IoT cost-effective, most deployments employ unlicensed ISM bands, specifically the 2400 MHz one, due to its extended communication bandwidth in comparison with lower bands. This band has been extensively used for years by Wireless Sensor Networks (WSN) and Mobile Ad-hoc Networks (MANET), from which the IoT technologically inherits. However, this work questions and evaluates the suitability of such a "default" communication band in SG environments, compared with the 915 MHz ISM band. A comprehensive quantitative comparison of these bands has been accomplished in terms of: power consumption, average network delay, and packet reception rate. To allow such a study, a dual-band propagation model specifically designed for the SG has been derived, tested, and incorporated into the well-known TOSSIM simulator. Simulation results reveal that only in the absence of other 2400 MHz interfering devices (such as WiFi or Bluetooth) or in small networks, is the 2400 MHz band the best option. In any other case, SG-oriented IoT quantitatively perform better if operating in the 915 MHz band.

Evaluating the More Suitable ISM Frequency Band for IoT-Based Smart Grids: A Quantitative Study of 915 MHz vs. 2400 MHz

PubMed Central

Sandoval, Ruben M.; Garcia-Sanchez, Antonio-Javier; Garcia-Sanchez, Felipe; Garcia-Haro, Joan

2016-01-01

IoT has begun to be employed pervasively in industrial environments and critical infrastructures thanks to its positive impact on performance and efficiency. Among these environments, the Smart Grid (SG) excels as the perfect host for this technology, mainly due to its potential to become the motor of the rest of electrically-dependent infrastructures. To make this SG-oriented IoT cost-effective, most deployments employ unlicensed ISM bands, specifically the 2400 MHz one, due to its extended communication bandwidth in comparison with lower bands. This band has been extensively used for years by Wireless Sensor Networks (WSN) and Mobile Ad-hoc Networks (MANET), from which the IoT technologically inherits. However, this work questions and evaluates the suitability of such a “default” communication band in SG environments, compared with the 915 MHz ISM band. A comprehensive quantitative comparison of these bands has been accomplished in terms of: power consumption, average network delay, and packet reception rate. To allow such a study, a dual-band propagation model specifically designed for the SG has been derived, tested, and incorporated into the well-known TOSSIM simulator. Simulation results reveal that only in the absence of other 2400 MHz interfering devices (such as WiFi or Bluetooth) or in small networks, is the 2400 MHz band the best option. In any other case, SG-oriented IoT quantitatively perform better if operating in the 915 MHz band. PMID:28042863

FIBER OPTICS. ACOUSTOOPTICS: High-frequency magnetooptics of fiber waveguides

NASA Astrophysics Data System (ADS)

Antonov, S. N.; Bulyuk, A. N.; Vetoshko, P. M.; Shkerdin, G. N.

1990-07-01

An investigation is made of the hf distributed magnetooptic interaction in fiber waveguides associated with the Faraday effect observed under the conditions of both spatial and temporal phase matching between the normal modes of the waveguide and an external magentic field. Analytic expressions are obtained for the main relationships governing modulation of the state of polarization of light in a long fiber waveguide at high and ultrahigh frequencies. An analysis is made of several variants of hf magnetooptic modulators. It is shown that in the specific case when a 10-m long quartz fiber waveguide wound to form a cylindrical coil is placed inside the cavity of a coaxial microwave resonator and the microwave control power is 10 W, the efficiency of modulation of light should be 50%. The main theoretical predictions were supported by the reported experiments. These experiments showed that at a frequency of 80 MHz the modulation efficiency was 1% when the control power was 0.5 W.

Electron Information in Single- and Dual-Frequency Capacitive Discharges at Atmospheric Pressure.

PubMed

Park, Sanghoo; Choe, Wonho; Moon, Se Youn; Shi, Jian Jun

2018-05-14

Determining the electron properties of weakly ionized gases, particularly in a high electron-neutral collisional condition, is a nontrivial task; thus, the mechanisms underlying the electron characteristics and electron heating structure in radio-frequency (rf) collisional discharges remain unclear. Here, we report the electrical characteristics and electron information in single-frequency (4.52 MHz and 13.56 MHz) and dual-frequency (a combination of 4.52 MHz and 13.56 MHz) capacitive discharges within the abnormal α-mode regime at atmospheric pressure. A continuum radiation-based electron diagnostic method is employed to estimate the electron density (n e ) and temperature (T e ). Our experimental observations reveal that time-averaged n e (7.7-14 × 10 11  cm -3 ) and T e (1.75-2.5 eV) can be independently controlled in dual-frequency discharge, whereas such control is nontrivial in single-frequency discharge, which shows a linear increase in n e and little to no change in T e with increases in the rf input power. Furthermore, the two-dimensional spatiotemporal evolution of neutral bremsstrahlung and associated electron heating structures is demonstrated. These results reveal that a symmetric structure in electron heating becomes asymmetric (via a local suppression of electron temperature) as two-frequency power is simultaneously introduced.

Optical Frequency Measurements Relying on a Mid-Infrared Frequency Standard

NASA Astrophysics Data System (ADS)

Rovera, G. Daniele; Acef, Ouali

Only a small number of groups are capable of measuring optical frequencies throughout the world. In this contribution we present some of the underlying philosophy of such frequency measurement systems, including some important theoretical hints. In particular, we concentrate on the approach that has been used with the BNM-LPTF frequency chain, where a separate secondary frequency standard in the mid-infrared has been used. The low-frequency section of the chain is characterized by a measurement of the phase noise spectral density Sφ at 716GHz.Most of the significant measurements performed in the last decade are briefly presented, together with a report on the actual stability and reproducibility of the CO2/ OsO4 frequency standard.Measuring the frequency of an optical frequency standard by direct comparison with the signal available at the output of a primary frequency standard (usually between 5MHz and 100MHz) requires a multiplication factor greater than 107. A number of possible configurations, using harmonic generation, sum or difference frequency generation, have been proposed and realized in the past [1,2,3,4,5,6] and in more recent times [7]. A new technique, employing a femtosecond laser, is presently giving its first impressive results [8].All of the classical frequency chains require a large amount of manpower, together with a great deal of simultaneously operating hardware. This has the consequence that only a very few systems are actually in an operating condition throughout the world.

47 CFR 15.239 - Operation in the band 88-108 MHz.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Intentional Radiators Radiated Emission Limits, Additional Provisions § 15.239 Operation in the band 88-108 MHz. (a) Emissions from the intentional radiator shall be confined within a band 200 kHz wide centered... the general radiated emission limits in § 15.209. (d) A custom built telemetry intentional radiator...

Low Frequency Variants, Collapsed Based on Biological Knowledge, Uncover Complexity of Population Stratification in 1000 Genomes Project Data

PubMed Central

Moore, Carrie B.; Wallace, John R.; Wolfe, Daniel J.; Frase, Alex T.; Pendergrass, Sarah A.; Weiss, Kenneth M.; Ritchie, Marylyn D.

2013-01-01

Analyses investigating low frequency variants have the potential for explaining additional genetic heritability of many complex human traits. However, the natural frequencies of rare variation between human populations strongly confound genetic analyses. We have applied a novel collapsing method to identify biological features with low frequency variant burden differences in thirteen populations sequenced by the 1000 Genomes Project. Our flexible collapsing tool utilizes expert biological knowledge from multiple publicly available database sources to direct feature selection. Variants were collapsed according to genetically driven features, such as evolutionary conserved regions, regulatory regions genes, and pathways. We have conducted an extensive comparison of low frequency variant burden differences (MAF<0.03) between populations from 1000 Genomes Project Phase I data. We found that on average 26.87% of gene bins, 35.47% of intergenic bins, 42.85% of pathway bins, 14.86% of ORegAnno regulatory bins, and 5.97% of evolutionary conserved regions show statistically significant differences in low frequency variant burden across populations from the 1000 Genomes Project. The proportion of bins with significant differences in low frequency burden depends on the ancestral similarity of the two populations compared and types of features tested. Even closely related populations had notable differences in low frequency burden, but fewer differences than populations from different continents. Furthermore, conserved or functionally relevant regions had fewer significant differences in low frequency burden than regions under less evolutionary constraint. This degree of low frequency variant differentiation across diverse populations and feature elements highlights the critical importance of considering population stratification in the new era of DNA sequencing and low frequency variant genomic analyses. PMID:24385916

Studies of radio frequency interference at Parkes Observatory

NASA Astrophysics Data System (ADS)

Backus, Peter R.; Laroque, Sam; Tarter, Jill C.; Dreher, John; Gullers, Kent; Patrick, Alan; Heiligman, Gary

1997-01-01

From February through early June 1995, Project Phoenix conducted SETI observations of 209 stars over the frequency range from 1195 to 3005 MHz. A byproduct of this search is a unique data set suitable for studying the Radio Frequency Interference (RFI) environment at the Parkes 64-m telescope in New South Wales, Australia. RFI is an increasing problem for SETI and other radio astronomy observations conducted outside of the 'protected' frequency bands. The data analyzed for this paper were 'mean baseline' spectra in Left and Right Circular Polarization (LCP, RCP), integrated for either 138 or 276 s, covering a 10-MHz bandwidth with 15,552 channels at a resolution of 643 Hz. Channels were identified as contaminated by RFI when the power in the channel exceeded the mean noise by 3 percent. The 'spectral occupancy', the fraction of time RFI was seen, was determined for each channel. The RFI occupancy for LCP and RCP are distinctly different. Approximately 100 MHz of the spectrum was too heavily contaminated for SETI observations.

Study Regarding Electromagnetic Radiation Exposure Generated By Mobile Phone

NASA Astrophysics Data System (ADS)

Marica, Lucia; Moraru, Luminita

2011-12-01

Number of mobile phone users reached to 5 billion subscribers in 2010 [ABI Research, 2010]. A large number of studies illustrated the public concern about adverse effects of mobile phone radiation and possible health hazards. Position of mobile phone use in close proximity to the head leads the main radiation between the hand and the head. Many investigations studying the possible effects of mobile phone exposure, founded no measurable effects of short-term mobile phone radiation, and there was no evidence for the ability to perceive mobile phone EMF in the general population. In this study, field radiation measurements were performed on different brand and different models of mobile phones in active mode, using an EMF RF Radiation Field Strength Power Meter 1 MHz-8 GHz. The study was effectuated on both the 2G and 3G generations phones connected to the providers operating in the frequency range 450 MHz-1800 MHz. There were recorded values in outgoing call and SMS mode, incoming call and SMS mode. Results were compared with ICNIRP guidelines for exposure to general public.

[The specific features of the development of metabolic and regenerative processes under the action of low-intensity electromagnetic radiation in radiation exposure conditions (an experimental study)].

PubMed

Korolev, Yu N; Mihajlik, L V; Nikulina, L A; Geniatulina, M S

The experiments on male white rats with the use of biochemical, photo-optical, and electron-microscopic techniques have demonstrated that the use of low-intensity electromagnetic radiation of ultrahigh frequency (EMR UHF) and low-intensity low-frequency magnetic field (MF) during the post-irradiation period (within 21 days after exposure to radiation) enhanced the metabolic and regenerative processes in the testes and liver. It was shown that the application of MF largely intensified the antioxidant activity whereas EMR UHF preferentially stimulated the biosynthetic processes as well as the processes of cellular and intracellular regeneration.

Radiation power and linewidth of a semifluxon-based Josephson oscillator

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

Paramonov, M.; Fominsky, M. Yu.; Koshelets, V. P.

We demonstrate a high-frequency generator operating at ∼200 GHz based on flipping a semifluxon in a Josephson junction of moderate normalized length. The semifluxon spontaneously appears at the π discontinuity of the Josephson phase artificially created by means of two tiny current injectors. The radiation is detected by an on-chip detector (tunnel junction). The estimated radiation power (at the detector) is ∼8 nW and should be compared with the dc power of ∼100 nW consumed by the generator. The measured radiation linewidth, as low as 1.1 MHz, is typical for geometrical (Fiske) resonances, although we tried to suppress such resonances by placing well-matched microwavemore » transformers at its both ends. Making use of a phase-locking feedback loop, we are able to reduce the radiation linewidth to less than 1 Hz measured relative to the reference oscillator and defined just by the resolution of our measurement setup.« less

Impacts of exposure to 900 MHz mobile phone radiation on liver function in rats.

PubMed

Ma, Hui-rong; Ma, Zhi-hong; Wang, Gui-ying; Song, Cui-miao; Ma, Xue-lian; Cao, Xiao-hui; Zhang, Guo-hong

2015-11-01

To study the impacts of exposure to electromagnetic radiation (EMR) on liver function in rats. Twenty adult male Sprague-Dawley rats were randomly divided into normal group and radiated group. The rats in normal group were not radiated, those in radiated group were exposed to EMR 4 h/ d for 18 consecutive days. Rats were sacrificed immediately after the end of the experiment. The serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and those of malondialdehyde (MDA) and glutathione (GSH) in liver tissue were evaluated by colorimetric method. The liver histopathological changes were observed by hematoxylin and eosin staining and the protein expression of bax and bcl- 2 in liver tissue were detected by immunohistochemical method. Terminal-deoxynucleotidyl transferase mediated nick and labelling (TUNEL) method was used for analysis of apoptosis in liver. Compared with the normal rats, the serum levels of ALT and AST in the radiated group had no obvious changes (P>0.05), while the contents of MDA increased (P < 0.01) and those of GSH decreased (P < 0.01) in liver tissues. The histopathology examination showed diffuse hepatocyte swelling and vacuolation, small pieces and focal necrosis. The immunohistochemical results displayed that the expression of the bax protein was higher and that of bcl-2 protein was lower in radiated group. The hepatocyte apoptosis rates in radiated group was higher than that in normal group (all P < 0.01). The exposure to 900 MHz mobile phone 4 h/d for 18 days could induce the liver histological changes, which may be partly due to the apoptosis and oxidative stress induced in liver tissue by electromagnetic radiation.

Effect of ultrasound frequency on the Nakagami statistics of human liver tissues.

PubMed

Tsui, Po-Hsiang; Zhou, Zhuhuang; Lin, Ying-Hsiu; Hung, Chieh-Ming; Chung, Shih-Jou; Wan, Yung-Liang

2017-01-01

The analysis of the backscattered statistics using the Nakagami parameter is an emerging ultrasound technique for assessing hepatic steatosis and fibrosis. Previous studies indicated that the echo amplitude distribution of a normal liver follows the Rayleigh distribution (the Nakagami parameter m is close to 1). However, using different frequencies may change the backscattered statistics of normal livers. This study explored the frequency dependence of the backscattered statistics in human livers and then discussed the sources of ultrasound scattering in the liver. A total of 30 healthy participants were enrolled to undergo a standard care ultrasound examination on the liver, which is a natural model containing diffuse and coherent scatterers. The liver of each volunteer was scanned from the right intercostal view to obtain image raw data at different central frequencies ranging from 2 to 3.5 MHz. Phantoms with diffuse scatterers only were also made to perform ultrasound scanning using the same protocol for comparisons with clinical data. The Nakagami parameter-frequency correlation was evaluated using Pearson correlation analysis. The median and interquartile range of the Nakagami parameter obtained from livers was 1.00 (0.98-1.05) for 2 MHz, 0.93 (0.89-0.98) for 2.3 MHz, 0.87 (0.84-0.92) for 2.5 MHz, 0.82 (0.77-0.88) for 3.3 MHz, and 0.81 (0.76-0.88) for 3.5 MHz. The Nakagami parameter decreased with the increasing central frequency (r = -0.67, p < 0.0001). However, the effect of ultrasound frequency on the statistical distribution of the backscattered envelopes was not found in the phantom results (r = -0.147, p = 0.0727). The current results demonstrated that the backscattered statistics of normal livers is frequency-dependent. Moreover, the coherent scatterers may be the primary factor to dominate the frequency dependence of the backscattered statistics in a liver.

Frequency characteristics of vibration generated by dual acoustic radiation force for estimating viscoelastic properties of biological tissues

NASA Astrophysics Data System (ADS)

Watanabe, Ryoichi; Arakawa, Mototaka; Kanai, Hiroshi

2018-07-01

We proposed a new method for estimating the viscoelastic property of the local region of a sample. The viscoelastic parameters of the phantoms simulating the biological tissues were quantitatively estimated by analyzing the frequency characteristics of displacement generated by acoustic excitation. The samples were locally strained by irradiating them with the ultrasound simultaneously generated from two point-focusing transducers by applying the sum of two signals with slightly different frequencies of approximately 1 MHz. The surface of a phantom was excited in the frequency range of 20–2,000 Hz, and its displacement was measured. The frequency dependence of the acceleration provided by the acoustic radiation force was also measured. From these results, we determined the frequency characteristics of the transfer function from the stress to the strain and estimated the ratio of the elastic modulus to the viscosity modulus (K/η) by fitting the data to the Maxwell model. Moreover, the elastic modulus K was separately estimated from the measured sound velocity and density of the phantom, and the viscosity modulus η was evaluated by substituting the estimated elastic modulus into the obtained K/η ratio.

47 CFR 80.379 - Maritime frequencies assignable to aircraft stations.

Code of Federal Regulations, 2010 CFR

2010-10-01

....300 MHz (5) 156.375 MHz (5) 156.400 MHz (5) 156.425 MHz (5) 156.450 MHz (5) 156.625 MHz (5) 156.800... aircraft stations does not exceed 300 meters (1,000 feet), except for reconnaissance aircraft participating in icebreaking operations where an altitude of 450 meters (1,500 feet) is allowed; (ii) The mean...

Search for nonthermal effects of 434 MHz microwave radiation on whole human blood

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

Dunscombe, P.B.; Gammampila, K.; Ramsey, N.W.

1983-11-01

Whole human blood was subjected to a microwave environment at 434 MHz for 6 h with external electric fields corresponding to free space power densities up to 598 mW cm/sup -2/ and the levels of hemoglobin, sodium, and potassium in the plasma were monitored. Under geometrical conditions in which the field strength within the samples was unknown, measurements indicated increased red cell membrane fragility following irradiation. It was possible to exclude localized heating as an explanation of this effect. However, with a known and reasonably uniform electric field distribution within spherical specimens, increased membrane fragility was not observed. We aremore » therefore unable to confirm previously reported results which indicate a nonthermal deleterious effect of microwave radiation on erythrocytes.« less

Radiated radiofrequency immunity testing of automated external defibrillators - modifications of applicable standards are needed

PubMed Central

2011-01-01

Background We studied the worst-case radiated radiofrequency (RF) susceptibility of automated external defibrillators (AEDs) based on the electromagnetic compatibility (EMC) requirements of a current standard for cardiac defibrillators, IEC 60601-2-4. Square wave modulation was used to mimic cardiac physiological frequencies of 1 - 3 Hz. Deviations from the IEC standard were a lower frequency limit of 30 MHz to explore frequencies where the patient-connected leads could resonate. Also testing up to 20 V/m was performed. We tested AEDs with ventricular fibrillation (V-Fib) and normal sinus rhythm signals on the patient leads to enable testing for false negatives (inappropriate "no shock advised" by the AED). Methods We performed radiated exposures in a 10 meter anechoic chamber using two broadband antennas to generate E fields in the 30 - 2500 MHz frequency range at 1% frequency steps. An AED patient simulator was housed in a shielded box and delivered normal and fibrillation waveforms to the AED's patient leads. We developed a technique to screen ECG waveforms stored in each AED for electromagnetic interference at all frequencies without waiting for the long cycle times between analyses (normally 20 to over 200 s). Results Five of the seven AEDs tested were susceptible to RF interference, primarily at frequencies below 80 MHz. Some induced errors could cause AEDs to malfunction and effectively inhibit operator prompts to deliver a shock to a patient experiencing lethal fibrillation. Failures occurred in some AEDs exposed to E fields between 3 V/m and 20 V/m, in the 38 - 50 MHz range. These occurred when the patient simulator was delivering a V-Fib waveform to the AED. Also, we found it is not possible to test modern battery-only-operated AEDs for EMI using a patient simulator if the IEC 60601-2-4 defibrillator standard's simulated patient load is used. Conclusions AEDs experienced potentially life-threatening false-negative failures from radiated RF, primarily

Radiated radiofrequency immunity testing of automated external defibrillators--modifications of applicable standards are needed.

PubMed

Umberger, Ken; Bassen, Howard I

2011-07-29

We studied the worst-case radiated radiofrequency (RF) susceptibility of automated external defibrillators (AEDs) based on the electromagnetic compatibility (EMC) requirements of a current standard for cardiac defibrillators, IEC 60601-2-4. Square wave modulation was used to mimic cardiac physiological frequencies of 1-3 Hz. Deviations from the IEC standard were a lower frequency limit of 30 MHz to explore frequencies where the patient-connected leads could resonate. Also testing up to 20 V/m was performed. We tested AEDs with ventricular fibrillation (V-Fib) and normal sinus rhythm signals on the patient leads to enable testing for false negatives (inappropriate "no shock advised" by the AED). We performed radiated exposures in a 10 meter anechoic chamber using two broadband antennas to generate E fields in the 30-2500 MHz frequency range at 1% frequency steps. An AED patient simulator was housed in a shielded box and delivered normal and fibrillation waveforms to the AED's patient leads. We developed a technique to screen ECG waveforms stored in each AED for electromagnetic interference at all frequencies without waiting for the long cycle times between analyses (normally 20 to over 200 s). Five of the seven AEDs tested were susceptible to RF interference, primarily at frequencies below 80 MHz. Some induced errors could cause AEDs to malfunction and effectively inhibit operator prompts to deliver a shock to a patient experiencing lethal fibrillation. Failures occurred in some AEDs exposed to E fields between 3 V/m and 20 V/m, in the 38 - 50 MHz range. These occurred when the patient simulator was delivering a V-Fib waveform to the AED. Also, we found it is not possible to test modern battery-only-operated AEDs for EMI using a patient simulator if the IEC 60601-2-4 defibrillator standard's simulated patient load is used. AEDs experienced potentially life-threatening false-negative failures from radiated RF, primarily below the lower frequency limit of present AED

The surface variation of Ti-14Al-21Nb as a function of temperature under ultrahigh vacuum conditions

NASA Technical Reports Server (NTRS)

Lee, W. S.; Sankaran, S. N.; Outlaw, R. A.; Clark, R. K.

1990-01-01

The effect of temperature, at conditions of ultrahigh vacuum, on the surface composition of the Ti-14Al-21Nb (in wt pct) alloy was investigated in samples heated to 1000 C in 100 C increments. Results of AES spectroscopy revealed that the Ti-14Al-21Nb alloy surface is extremely sensitive to temperature. At 300 C, the carbon and oxygen began to rapidly dissolve into the alloy, and at 600 C, bulk S segregated to the surface. The variation in the surface composition was extensive and different over the temperature range studied, indicating that there may be substantial changes in the hydrogen transport.

47 CFR 80.148 - Watch on 156.8 MHz (Channel 16).

Code of Federal Regulations, 2010 CFR

2010-10-01

... exchanging communications. For GMDSS ships, 156.525 MHz is the calling frequency for distress, safety, and general communications using digital selective calling and the watch on 156.800 MHz is provided so that... 80.148 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO...

Airborne urban/suburban noise measurements at 121.5/243 MHz

NASA Technical Reports Server (NTRS)

Taylor, R. E.; Hill, J. S.

1977-01-01

An airborne measurement of the terrestrial, radio-frequency (RF) noise environment over U.S. metropolitan urban/suburban areas has been made at the 121.5/243 MHz emergency-distress search and rescue (S&R) communications frequencies. Profile contour plots of antenna-noise temperature for U.S.A. East Coast and mid-west urban/suburban areas is presented for daytime/nighttime observations at 121.5/243 MHz. These plots are helpful for compiling radio-noise environment maps; in turn useful for designing satellite-aided, emergency-distress search and rescue communication systems.

Review of measurements of the RF spectrum of radiation from lightning

NASA Technical Reports Server (NTRS)

Levine, D. M.

1986-01-01

Measurements reported in the literature of the spectrum of electromagnetic radiation from lightning in the frequency range from 1 kHz to 1 GHz are reviewed. Measurements have been made either by monitoring the power received at individual frequencies using a narrow bandwidth recording device tuned to the frequencies under investigation or by recording the transient (time dependent) radiation with a wide bandwidth device and then Fourier transforming the waveform to obtain a spectrum. Measurements of the first type were made extensively in the 1950's and 1960's and several composite spectra have been deduced by normalizing the data of different investigators to common units of bandwidth and distance. The composite spectra tend to peak near 5 kHz and then decrease roughly as (frequency) to the -1, up to nearly 100 MHz where scatter in the data make the behavior uncertain. Measurements of the second type have been reported for return strokes, the stepped leader and for some intracloud processes. The spectrum of first return strokes obtained in this manner is very similar to the composite spectra obtained from the narrow-band measurements.

Observation of the seismic anisotropy effects on free oscillations below 4 mHz

NASA Astrophysics Data System (ADS)

Hu, X.; Liu, L.

2009-12-01

We present observations of significant fundamental spheroidal-toroidal mode coupling at frequencies below 4 mHz in the early part of vertical component records from seismic stations on near-equatorial source-receiver propagation paths and in Antarctica after the 26 December 2004 and 28 March 2005 great Sumatra earthquakes. When seismic surface waves propagate along the equator, the particle motion of Love waves runs parallels to the Earth’s rotation axis, and the particle motion of Rayleigh waves runs perpendicular to it, thus the Coriolis force has no vertical deflection effect on Love waves and no transverse deflection effect on the Rayleigh waves. Coriolis coupling can be naturally minimized at a station on a nearequatorial source-receiver propagation path. In Antarctica, especially near the South Pole, the vertical deflection of toroidial motion is very weak but there are lateral gradients in the anisotropic properties of upper mantle. Therefore, we can find a chance to directly observe seismic anisotropy coupling below 4 mHz without the disturbance of Coriolis coupling at Antarctic station, and at the seismic station locate close to the Earth’s equator when the epicenter also locates close to the equator. Our observations of strong anomalous toroidal-spheroidal coupling at these stations provide direct evidence to confirm the theory that the azimuthal anisotropy has pronounced effects on the quasi-toroidal mode excitations at the frequencies below 4 mHz, which can convince the skeptics that anisotropy really is visible in the low-frequency normal mode data. Strong anisotropic coupling is usually observed at stations having the geometric nodes for the spheroidal fundamentals, giving the association of quasi-toroidal excitation with the geometric effect. The presence of significant anisotropy coupling below 4 mHz depends not only on anisotropic depth, anisotropic identities and orientations but also on radiation nodes for Rayleigh waves and geometry nodes

Magnetic Resonance Imaging at Ultrahigh Fields

PubMed Central

Uğurbil, Kamil

2014-01-01

Since the introduction of 4 T human systems in three academic laboratories circa 1990, rapid progress in imaging and spectroscopy studies in humans at 4 T and animal model systems at 9.4 T have led to the introduction of 7 T and higher magnetic fields for human investigation at about the turn of the century. Work conducted on these platforms has demonstrated the existence of significant advantages in SNR and biological information content at these ultrahigh fields, as well as the presence of numerous challenges. Primary difference from lower fields is the deviation from the near field regime; at the frequencies corresponding to hydrogen resonance conditions at ultrahigh fields, the RF is characterized by attenuated traveling waves in the human body, which leads to image nonuniformities for a given sample-coil configuration because of interferences. These nonuniformities were considered detrimental to the progress of imaging at high field strengths. However, they are advantageous for parallel imaging for signal reception and parallel transmission, two critical technologies that account, to a large extend, for the success of ultrahigh fields. With these technologies, and improvements in instrumentation and imaging methods, ultra-high fields have provided unprecedented gains in imaging of brain function and anatomy, and started to make inroads into investigation of the human torso and extremities. As extensive as they are, these gains still constitute a prelude to what is to come given the increasingly larger effort committed to ultrahigh field research and development of ever better instrumentation and techniques. PMID:24686229

Dielectric study of aqueous solutions of sodium dodecyl sulfate in the frequency span 20 Hz to 2 MHz

NASA Astrophysics Data System (ADS)

Kadve, A. M.; Vankar, H. P.; Rana, V. A.

2017-05-01

Dielectric measurements were carried out for aqueous solutions of Sodium Dodecyl Sulfate (SDS) in the frequency span of 20 Hz to 2 MHz at 300.15 K temperature using precision LCR meter. Also the refractive indices were measured for the solutions at 300.15 K temperature using Abbe's refractometer. The measurements were done for ten different concentrations of SDS in distilled water. Determined values of complex permittivity as a function of frequency were used to evaluate other parameters like loss tangent and electric modulus for the liquid samples. The permittivity at optical frequency were also calculated from the measured refractive indices for the aqueous solutions. The effect of concentration variation of SDS in the aqueous solutions on the determined parameters is discussed.

Counter-evidence against multiple frequency nature of 0.75 mHz oscillation in V4743 Sgr

NASA Astrophysics Data System (ADS)

Dobrotka, A.; Ness, J.-U.

2017-06-01

All X-ray light curves of nova V4743 Sgr (2002), taken during and after outburst, contain a 0.75 mHz periodic signal that can most plausibly be interpreted as being excited by the rotation of the white dwarf in an intermediate polar system. This interpretation faces the challenge of an apparent multifrequency nature of this signal in the light curves taken days 180 and 196 after outburst. We show that the multisine fit method, based on a superposition of two sine functions, yields two inherently indistinguishable solutions, I.e. the presence of two close frequencies, or a single signal with constant frequency but variable modulation amplitude. Using a power spectrum time map, we show that on day 180, a reduction of the modulation amplitude of the signal coincides with a substantial overall flux decline, while on day 196, the signal is present only during the first half of the observation. Supported by simulations, we show that such variations in amplitude can lead to false beating, which manifests itself as a multiple signal if computing a periodogram over the full light curve. Therefore, the previously proposed double-frequency nature of both light curves was probably an artefact, while we consider a single signal with frequency equal to the white dwarf rotation as more plausible.

Narrow-band, slowly varying decimetric radiation from the dwarf M flare star YZ Canis Minoris

NASA Technical Reports Server (NTRS)

Lang, K. R.; Willson, R. F.

1986-01-01

Observations of slowly varying radiation from the dwarf M star YZ Canis Minoris with a maximum flux density of 20 mJy and narrow-band frequency structure at frequencies near 1465 MHz are presented. Possible explanations for this radiation are examined. Thermal gyroresonant radiation would require impossibly large coronal loops and magnetic field strengths. The narrow-band structure cannot be explained by continuum emission processes such as thermal bremsstrahlung, thermal gyroresonant radiation, or nonthermal gyrosynchrotron radiation. Coherent burst mechanisms seem to be required.

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.

Frequency control of tunable lasers using a frequency-calibrated λ-meter in an experiment on preparation of Rydberg atoms in a magneto-optical trap

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

Saakyan, S A; Vilshanskaya, E V; Zelener, B B

2015-09-30

A new technique is proposed and applied to study the frequency drift of an external-cavity semiconductor laser, locked to the transmission resonances of a thermally stabilised Fabry–Perot interferometer. The interferometer frequency drift is measured to be less than 2 MHz h{sup -1}. The laser frequency is measured using an Angstrom wavemeter, calibrated using an additional stabilised laser. It is shown that this system of laser frequency control can be used to identify Rydberg transitions in ultracold {sup 7}Li atoms. (control of laser radiation parameters)

Study of Ultra-High Energy Cosmic Rays from Extensive Air Showers Radio Emission

NASA Astrophysics Data System (ADS)

Petrov, Igor; Kozlov, Vladimir; Petrov, Zim; Knurenko, Stanislav; Pravdin, Mikhail

The study of cosmic rays with the help of radio detection from extensive air showers may be an alternative to traditional detecting methods, which use a large area array installed with hundreds and thousands of scintillation detectors for charged particles, or the detectors of measuring the emission produced by relativistic particles of EAS in the optical wavelengths. Processes that lead to the emission of electromagnetic radiation are well known and calculations show that the air shower radio emission depends on the processes of development of the electromagnetic cascade, i.e. related with the longitudinal development of the shower, with the magnetic field near sea level etc. In this regard, there is a question to establish the correlation between characteristics of EAS both longitudinal and lateral development and radio emission parameters observed when air shower particles pass through the atmosphere. For this purpose, in Yakutsk, radio array for detecting air shower radio emission was established. The array consists of the antenna field on which crossed antennas are installed; antennas oriented E - W and N - S. Radio emission measurements are conducted at frequency 32 MHz, free from industrial noise. In 2008 - 2013 years, Yakutsk array has measured several seasons of registration of EAS events, including showers with energies above 10 (19) eV. In the course of the data analysis the following results were obtained: a) lateral distribution of the radio signal plotted as a function of distance from the shower axis ; b) a correlation between the amplitude of the radio signal with the energy of the shower, which is determined by measuring the fluxes of charged particles , muons and EAS Cerenkov radiation (energy balance method); c) we made evaluation of the depth of maximum development of the shower using form of radio emission LDF measured in ultra-high energy showers; g) a comparison of the Yakutsk array data with data from other arrays.

High frequency EMI sensing for estimating depleted uranium radiation levels in soil

NASA Astrophysics Data System (ADS)

Shubitidze, Fridon; Barrowes, Benjamin E.; Ballard, John; Unz, Ron; Randle, Adam; Larson, Steve L.; O'Neill, Kevin A.

2018-04-01

This paper studies high (100 kHz up to 15 MHz) frequency electromagnetic responses (HFEMI) for DU metallic pieces and DU contaminated soils and derives a simple empirical expression from the measured HFEMI data for estimating DU contamination levels in soil. Depleted uranium (DU) is the byproduct of uranium enrichment and contains 33% less radioactive isotopes than natural uranium. There are at least thirty facilities at fourteen separate locations in the US, where munitions containing DU have been evaluated or used for training. At these sites, which vary in size, evaluation studies have been conducted with and without catch boxes. In addition, the DoD used DU at open firing ranges as large as thousands of acres (hundreds of hectares), for both artillery and aircraft training. These activities have left a legacy of DU contamination. Currently at military sites where DU munitions have been or are being used, cleanup activities mainly are done by excavating and shipping large volumes of site soil and berm materials to a hazardous material radiation disposal site. This approach is very time consuming, costly, and associated with the potential for exposure of personnel performing excavation and transportation. It also limits range use during the operation. So, there is an urgent need for technologies for rapid surveying of large areas to detect, locate, and removal of DU contaminants at test sites. Additionally, the technologies are needed to detect material at a depth of at least 30 cm as well as discriminate between DU metals and oxides from natural uranium and from other conductive metals such as natural and man-made range clutter. One of the potential technologies for estimating DU radiation levels in soils is HFEMI sensing. In this paper, HFEMI signals are collected for DU metal pieces, sodium diunarate (Na2U2 O3) and tri-uranium octoxide (U3O8). The EMI signal's sensitivity with respect to DU material composition and conditions are illustrated and analyzed. A

Wireless network of stand-alone end effect probes for soil in situ permittivity measurements over the 100MHZ-6GHz frequency range

NASA Astrophysics Data System (ADS)

Demontoux, François; Bircher, Simone; Ruffié, Gilles; Bonnaudiin, Fabrice; Wigneron, Jean-Pierre; Kerr, Yann

2017-04-01

Microwave remote sensing and non-destructive analysis are a powerful way to provide properties estimation of materials. Numerous applications using microwave frequency behavior of materials (remote sensing above land surfaces, non-destructive analysis…) are strongly dependent on the material's permittivity (i.e. dielectric properties). This permittivity depends on numerous parameters such as moisture, texture, temperature, frequency or bulk density. Permittivity measurements are generally carried out in the laboratory. Additionally, dielectric mixing models allow, over a restricted range of conditions, the assessment of a material's permittivity. in-situ measurements are more difficult to obtain. Some in situ measurement probes based on permittivity properties of soil exist (e.g. Time Domain Reflectometers and Transmissometers, capacitance and impedance sensors). They are dedicated to the acquisition of soil moisture data based on permittivity (mainly the real part) estimations over a range of frequencies from around 50 MHz to 1 or 2 GHz. Other Dielectric Assessment Kits exist but they are expensive and they are rather dedicated to laboratory measurements. Furthermore, the user can't address specific issues related to particular materials (e.g. organic soils) or specific measurement conditions (in situ long time records). At the IMS Laboratory we develop probes for in situ soil permittivity measurements (real and imaginary parts) in the 0.5 - 6 GHz frequency range. They are based on the end effect phenomenon of a coaxial waveguide and so are called end effect probes in this paper. The probes can be connected to a portable Vector Network Analyzer (VNA, ANRITSU MS2026A) for the S11 coefficient measurements needed to compute permittivity. It is connected to a PC to record data using an USB connection. This measurement set-up is already used for in situ measurement of soil properties in the framework of the European Space Agency's (ESA) SMOS space mission. However

Study Regarding Electromagnetic Radiation Exposure Generated By Mobile Phone

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

Marica, Lucia; Moraru, Luminita

Number of mobile phone users reached to 5 billion subscribers in 2010 [ABI Research, 2010]. A large number of studies illustrated the public concern about adverse effects of mobile phone radiation and possible health hazards. Position of mobile phone use in close proximity to the head leads the main radiation between the hand and the head. Many investigations studying the possible effects of mobile phone exposure, founded no measurable effects of short-term mobile phone radiation, and there was no evidence for the ability to perceive mobile phone EMF in the general population. In this study, field radiation measurements were performedmore » on different brand and different models of mobile phones in active mode, using an EMF RF Radiation Field Strength Power Meter 1 MHz-8 GHz. The study was effectuated on both the 2G and 3G generations phones connected to the providers operating in the frequency range 450 MHz-1800 MHz. There were recorded values in outgoing call and SMS mode, incoming call and SMS mode. Results were compared with ICNIRP guidelines for exposure to general public.« less

A micromachined efficient parametric array loudspeaker with a wide radiation frequency band.

PubMed

Je, Yub; Lee, Haksue; Been, Kyounghun; Moon, Wonkyu

2015-04-01

Parametric array (PA) loudspeakers generate directional audible sound via the PA effect, which can make private listening possible. The practical applications of PA loudspeakers include information technology devices that require large power efficiency transducers with a wide frequency bandwidth. Piezoelectric micromachined ultrasonic transducers (PMUTs) are compact and efficient units for PA sources [Je, Lee, and Moon, Ultrasonics 53, 1124-1134 (2013)]. This study investigated the use of an array of PMUTs to make a PA loudspeaker with high power efficiency and wide bandwidth. The achievable maximum radiation bandwidth of the driver was calculated, and an array of PMUTs with two distinct resonance frequencies (f1 = 100 kHz, f2 = 110 kHz) was designed. Out-of-phase driving was used with the dual-resonance transducer array to increase the bandwidth. The fabricated PMUT array exhibited an efficiency of up to 71%, together with a ±3-dB bandwidth of 17 kHz for directly radiated primary waves, and 19.5 kHz (500 Hz to 20 kHz) for the difference frequency waves (with equalization).

Radio frequency radiation exposure of the F-15 crewmember.

PubMed

Laughrey, Michael S; Grayson, J Kevin; Jauchem, James R; Misener, Andrea E

2003-08-01

In the United States Air Force, pilots of F-15 fighter aircraft use fire control radars to search for enemy targets and to launch beyond visual range radar missiles. The fire control radars must be of a sufficient power output to enable a target return, but pilots are concerned about deleterious health effects from the levels of radio frequency radiation (RFR) they are exposed to. Measurement of RFR while actually in flight in the F-15 has never been performed. This study was designed to document the RFR levels that pilots are exposed to on normal missions while in flight with the radar on and active. A hand-held meter was used to measure electromagnetic fields during three F-15 flights. Instrumentation consisted of a Narda Microwave Model 8718 digital survey meter and Model 8723 broadband isotropic E-field probe with a frequency range between 300 MHz and 50 GHz. The measurements were conducted in the rear cockpit of an F-15D aircraft. Three missions were flown representing the standard missions an F-15 pilot flies on an everyday basis. The missions were: night intercepts, offensive basic fighter maneuvers, and defensive basic fighter maneuvers. Based on the data collected during three F-15 missions, all recorded RFR exposure to the crewmember in the F-15 was within the OSHA Permissible Exposure Limit (PEL) of 10 mW x cm(-2). Based on a limited sample, RFR exposures in F-15 cockpits appear to be well below the PEL.

High frequency ultrasound imaging using Fabry-Perot optical etalon

NASA Astrophysics Data System (ADS)

Ashkenazi, S.; Witte, R.; O'Donnell, M.

2005-04-01

Optical detection of ultrasound provides a unique and appealing way of forming detector arrays (1D or 2D) using either raster beam scanning or simultaneous array detection exploiting wide area illumination. Etalon based optical techniques are of particular interest, due to their relatively high sensitivity resulting from multiple optical reflections within the resonance structure. Detector arrays formed by etalon based techniques are characterized by high element density and small element active area, which enables high resolution imaging at high ultrasonic frequencies (typically 10-50 MHz). In this paper we present an application of an optical etalon structure for very high frequency ultrasound detection (exceeding 100 MHz). A thin polymer Fabry-Perot etalon (10 μm thickness) has been fabricated using spin coating of polymer photoresist on a glass substrate and gold evaporation forming partially reflecting mirrors on both faces of the polymer layer. The optical resonator formed by the etalon structure has a measured Q-factor of 300. The characteristic broadband response of the optical signal was demonstrated by insonifying the etalon using two different ultrasound transducers and recording the resulting intensity modulation of optical reflection from the etalon. A focused 10 MHz transducer was used for the low MHz frequency region, and a 50 MHz focused transducer was used for the high frequency region. The optical reflection signal was compared to the pulse/echo signal detected by the same ultrasound transducer. The measured signal to noise ratio of the optically detected signal is comparable to that of the pulse/echo signal in both low and high frequency ranges. The etalon detector was integrated in a photoacoustic imaging system. High resolution images of phantom targets and biological tissue (nerve cord) were obtained. The additional information of optical absorption obtained by photoacoustic imaging, along with the high resolution detection of the etalon

An improved offset generator developed for Allan deviation measurement of ultra stable frequency standards

NASA Technical Reports Server (NTRS)

Hamell, Robert L.; Kuhnle, Paul F.; Sydnor, Richard L.

1992-01-01

Measuring the performance of ultra stable frequency standards such as the Superconducting Cavity Maser Oscillator (SCMO) necessitates improvement of some test instrumentation. The frequency stability test equipment used at JPL includes a 1 Hz Offset Generator to generate a beat frequency between a pair of 100 MHz signals that are being compared. The noise floor of the measurement system using the current Offset Generator is adequate to characterize stability of hydrogen masers, but it is not adequate for the SCMO. A new Offset Generator with improved stability was designed and tested at JPL. With this Offset Generator and a new Zero Crossing Detector, recently developed at JPL, the measurement flow was reduced by a factor of 5.5 at 1 second tau, 3.0 at 1000 seconds, and 9.4 at 10,000 seconds, compared against the previous design. In addition to the new circuit designs of the Offset Generator and Zero Crossing Detector, tighter control of the measurement equipment environment was required to achieve this improvement. The design of this new Offset Generator are described, along with details of the environment control methods used.

Intravascular ultrasound catheter to enhance microbubble-based drug delivery via acoustic radiation force.

PubMed

Kilroy, Joseph P; Klibanov, Alexander L; Wamhoff, Brian R; Hossack, John A

2012-10-01

Previous research has demonstrated that acoustic radiation force enhances intravascular microbubble adhesion to blood vessels in the presence of flow for moleculartargeted ultrasound imaging and drug delivery. A prototype acoustic radiation force intravascular ultrasound (ARFIVUS) catheter was designed and fabricated to displace a microbubble contrast agent in flow representative of conditions encountered in the human carotid artery. The prototype ARFIVUS transducer was designed to match the resonance frequency of 1.4- to 2.6-μm-diameter microbubbles modeled by an experimentally verified 1-D microbubble acoustic radiation force translation model. The transducer element was an elongated Navy Type I (hard) lead zirconate titanate (PZT) ceramic designed to operate at 3 MHz. Fabricated devices operated with center frequencies of 3.3 and 3.6 MHz with -6-dB fractional bandwidths of 55% and 50%, respectively. Microbubble translation velocities as high as 0.86 m/s were measured using a high-speed streak camera when insonating with the ARFIVUS transducer. Finally, the prototype was used to displace microbubbles in a flow phantom while imaging with a commercial 45-MHz imaging IVUS transducer. A sustained increase of 31 dB in average video intensity was measured following insonation with the ARFIVUS, indicating microbubble accumulation resulting from the application of acoustic radiation force.

Ultrahigh contrast from a frequency-doubled chirped-pulse-amplification beamline.

PubMed

Hillier, David; Danson, Colin; Duffield, Stuart; Egan, David; Elsmere, Stephen; Girling, Mark; Harvey, Ewan; Hopps, Nicholas; Norman, Michael; Parker, Stefan; Treadwell, Paul; Winter, David; Bett, Thomas

2013-06-20

This paper describes frequency-doubled operation of a high-energy chirped-pulse-amplification beamline. Efficient type-I second-harmonic generation was achieved using a 3 mm thick 320 mm aperture KDP crystal. Shots were fired at a range of energies achieving more than 100 J in a subpicosecond, 527 nm laser pulse with a power contrast of 10(14).

ACCURATE POLARIZATION CALIBRATION AT 800 MHz WITH THE GREEN BANK TELESCOPE

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

Liao, Yu-Wei; Chang, Tzu-Ching; Kuo, Cheng-Yu

Polarization leakage of foreground synchrotron emission is a critical issue in H i intensity mapping experiments. While the sought-after H i emission is unpolarized, polarized foregrounds such as Galactic and extragalactic synchrotron radiation, if coupled with instrumental impurity, can mimic or overwhelm the H i signals. In this paper, we present the methodology for polarization calibration at 700–900 MHz, applied on data obtained from the Green Bank Telescope (GBT). We use astrophysical sources, both polarized and unpolarized sources including quasars and pulsars, as calibrators to characterize the polarization leakage and control systematic effects in our GBT H i intensity mapping project.more » The resulting fractional errors on polarization measurements on boresight are well controlled to within 0.6%–0.8% of their total intensity. The polarized beam patterns are measured by performing spider scans across both polarized quasars and pulsars. A dominant Stokes I to V leakage feature and secondary features of Stokes I to Q and I to U leakages in the 700–900 MHz frequency range are identified. These characterizations are important for separating foreground polarization leakage from the H i 21 cm signal.« less

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms.

PubMed

Pruttivarasin, Thaned; Katori, Hidetoshi

2015-11-01

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

Compact field programmable gate array-based pulse-sequencer and radio-frequency generator for experiments with trapped atoms

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

Pruttivarasin, Thaned, E-mail: thaned.pruttivarasin@riken.jp; Katori, Hidetoshi; Innovative Space-Time Project, ERATO, JST, Bunkyo-ku, Tokyo 113-8656

We present a compact field-programmable gate array (FPGA) based pulse sequencer and radio-frequency (RF) generator suitable for experiments with cold trapped ions and atoms. The unit is capable of outputting a pulse sequence with at least 32 transistor-transistor logic (TTL) channels with a timing resolution of 40 ns and contains a built-in 100 MHz frequency counter for counting electrical pulses from a photo-multiplier tube. There are 16 independent direct-digital-synthesizers RF sources with fast (rise-time of ∼60 ns) amplitude switching and sub-mHz frequency tuning from 0 to 800 MHz.

Modulation of auroral electron fluxes in the frequency range 50 kHz to 10 MHz

NASA Technical Reports Server (NTRS)

Spiger, R. J.; Murphree, J. S.; Anderson, H. R.; Loewenstein, R. F.

1976-01-01

A sounding rocket-borne electron detector of high time resolution is used to search for modulation of auroral electron fluxes in the frequency range 50 kHz to 10 MHz and energy range 5-7 keV. Data were telemetered to ground via a 93-kHz subcarrier. A cross-correlation analysis of the data collected indicates low-level modulation near the detection threshold of the instrument. Two U-1 events are observed which are interpreted as indications of modulation. The two modulation events occur during a period of increasing flux for a region marking the boundary between two current sheets detected by the payload magnetometer. The strongest argument against interference contamination is the lack of any observable modulation at times other than those mentioned in the study.

Ion energy distributions in a pulsed dual frequency inductively coupled discharge of Ar/CF{sub 4} and effect of duty ratio

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

Mishra, Anurag; Seo, Jin Seok; Kim, Tae Hyung

2015-08-15

Controlling time averaged ion energy distribution (IED) is becoming increasingly important in many plasma material processing applications for plasma etching and deposition. The present study reports the evolution of ion energy distributions with radio frequency (RF) powers in a pulsed dual frequency inductively discharge and also investigates the effect of duty ratio. The discharge has been sustained using two radio frequency, low (P{sub 2 MHz} = 2 MHz) and high (P{sub 13.56 MHz} = 13.56 MHz) at a pressure of 10 mTorr in argon (90%) and CF{sub 4} (10%) environment. The low frequency RF powers have been varied from 100 to 600 W, whereas the high frequency powers frommore » 200 to 1200 W. Typically, IEDs show bimodal structure and energy width (energy separation between the high and low energy peaks) increases with increasing P{sub 13.56 MHz}; however, it shows opposite trends with P{sub 2 MHz}. It has been observed that IEDs bimodal structure tends to mono-modal structure and energy peaks shift towards low energy side as duty ratio increases, keeping pulse power owing to mode transition (capacitive to inductive) constant.« less

High pulse repetition frequency ultrasound system for ex vivo measurement of mechanical properties of crystalline lenses with laser-induced microbubble interrogated by acoustic radiation force

PubMed Central

Yoon, Sangpil; Aglyamov, Salavat; Karpiouk, Andrei; Emelianov, Stanislav

2012-01-01

A high pulse repetition frequency ultrasound system for ex vivo measurement of mechanical properties of animal crystalline lens was developed and validated. We measured the bulk displacement of laser-induced microbubbles created at different positions within the lens using nanosecond laser pulses. An impulsive acoustic radiation force was applied to the microbubble, and spatio-temporal measurements of the microbubble displacement were assessed using a custom-made high pulse repetition frequency ultrasound system consisting of two 25 MHz focused ultrasound transducers. One of these transducers was used to emit a train of ultrasound pulses and another transducer was used to receive the ultrasound echoes reflected from the microbubble. The developed system was operating at 1 MHz pulse repetition frequency. Based on measured motion of the microbubble, the Young’s moduli of surrounding tissue were reconstructed and the values were compared with those measured using indentation test. Measured values of Young’s moduli of 4 bovine lenses ranged from 2.6±0.1 to 26±1.4 kPa and there was good agreement between the two methods. Therefore, our studies, utilizing the high pulse repetition frequency ultrasound system, suggest that the developed approach can be used to assess the mechanical properties of ex vivo crystalline lenses. Furthermore, the potential of the presented approach for in vivo measurements is discussed. PMID:22797709

Separation of major catechins from green tea by ultrahigh pressure extraction.

PubMed

Jun, Xi; Shuo, Zhao; Bingbing, Lu; Rui, Zhang; Ye, Li; Deji, Shen; Guofeng, Zhou

2010-02-15

This study presents a novel extraction technique, ultrahigh pressure extraction, to obtain major catechins from green tea leaves. The effects of various high pressure level (100, 200, 300, 400, 500, 600 MPa) on the extract are examined. HPLC chromatographic analyses determine the concentration of four major catechins and caffeine. The extraction yields of active ingredients with ultrahigh pressure extraction (400 MPa pressure) for only 15 min were given the same as those of organic solvent extraction for 2h. These excellent results for the ultrahigh pressure extraction are promising for the future separation of active ingredients from traditional Chinese herbal medicine. Copyright 2009 Elsevier B.V. All rights reserved.

Frequency-tuning radiofrequency plasma source operated in inductively-coupled mode under a low magnetic field

NASA Astrophysics Data System (ADS)

Takahashi, Kazunori; Nakano, Yudai; Ando, Akira

2017-07-01

A radiofrequency (rf) inductively-coupled plasma source is operated with a frequency-tuning impedance matching system, where the rf frequency is variable in the range of 20-50 MHz and the maximum power is 100 W. The source consists of a 45 mm-diameter pyrex glass tube wound by an rf antenna and a solenoid providing a magnetic field strength in the range of 0-200 Gauss. A reflected rf power for no plasma case is minimized at the frequency of ˜25 MHz, whereas the frequency giving the minimum reflection with the high density plasma is about 28 MHz, where the density jump is observed when minimizing the reflection. A high density argon plasma above 1× {{10}12} cm-3 is successfully obtained in the source for the rf power of 50-100 W, where it is observed that an external magnetic field of a few tens of Gauss yields the highest plasma density in the present configuration. The frequency-tuning plasma source is applied to a compact and high-speed silicon etcher in an Ar-SF6 plasma; then the etching rate of 8~μ m min-1 is obtained for no bias voltage to the silicon wafer, i.e. for the case that a physical ion etching process is eliminated.

Ultrahigh-speed non-invasive widefield angiography

NASA Astrophysics Data System (ADS)

Blatter, Cedric; Klein, Thomas; Grajciar, Branislav; Schmoll, Tilman; Wieser, Wolfgang; Andre, Raphael; Huber, Robert; Leitgeb, Rainer A.

2012-07-01

Retinal and choroidal vascular imaging is an important diagnostic benefit for ocular diseases such as age-related macular degeneration. The current gold standard for vessel visualization is fluorescence angiography. We present a potential non-invasive alternative to image blood vessels based on functional Fourier domain optical coherence tomography (OCT). For OCT to compete with the field of view and resolution of angiography while maintaining motion artifacts to a minimum, ultrahigh-speed imaging has to be introduced. We employ Fourier domain mode locking swept source technology that offers high quality imaging at an A-scan rate of up to 1.68 MHz. We present retinal angiogram over ˜48 deg acquired in a few seconds in a single recording without the need of image stitching. OCT at 1060 nm allows for high penetration in the choroid and efficient separate characterization of the retinal and choroidal vascularization.

Ultra-high strain in epitaxial silicon carbide nanostructures utilizing residual stress amplification

NASA Astrophysics Data System (ADS)

Phan, Hoang-Phuong; Nguyen, Tuan-Khoa; Dinh, Toan; Ina, Ginnosuke; Kermany, Atieh Ranjbar; Qamar, Afzaal; Han, Jisheng; Namazu, Takahiro; Maeda, Ryutaro; Dao, Dzung Viet; Nguyen, Nam-Trung

2017-04-01

Strain engineering has attracted great attention, particularly for epitaxial films grown on a different substrate. Residual strains of SiC have been widely employed to form ultra-high frequency and high Q factor resonators. However, to date, the highest residual strain of SiC was reported to be limited to approximately 0.6%. Large strains induced into SiC could lead to several interesting physical phenomena, as well as significant improvement of resonant frequencies. We report an unprecedented nanostrain-amplifier structure with an ultra-high residual strain up to 8% utilizing the natural residual stress between epitaxial 3C-SiC and Si. In addition, the applied strain can be tuned by changing the dimensions of the amplifier structure. The possibility of introducing such a controllable and ultra-high strain will open the door to investigating the physics of SiC in large strain regimes and the development of ultra sensitive mechanical sensors.

Human serum albumin adsorption study on 62-MHz miniaturized quartz gravimetric sensors.

PubMed

Kao, Ping; Patwardhan, Ashish; Allara, David; Tadigadapa, Srinivas

2008-08-01

We have designed and fabricated 25-microm-thick quartz resonators operating at a fundamental resonance frequency of approximately 62 MHz. The results show a substantial increase in the mass sensitivity compared to single monolithic commercial resonators operating at lower frequencies in the approximately 5-10-MHz range. The overall performance of the micromachined resonators is demonstrated for the example of human serum albumin protein adsorption from aqueous buffer solutions onto gold electrodes functionalized with self-assembled monolayers. The results show a saturation adsorption frequency change of 6.8 kHz as opposed to 40 Hz for a commercial approximately 5-MHz sensor under identical loading conditions. From the analysis of the adsorption isotherm, the equilibrium adsorption constant of the adsorption of the protein layer was found to be K = 8.03 x 10(6) M(-1), which is in agreement with the values reported in the literature. The high sensitivity of the miniaturized QCM devices can be a significant advantage in both vapor and solution adsorption analyses.

47 CFR 15.33 - Frequency range of radiated measurements.

Code of Federal Regulations, 2010 CFR

2010-10-01

... radiator operates at or above 30 GHz: to the fifth harmonic of the highest fundamental frequency or to 200... kHz, up to at least the frequency shown in this paragraph: (1) If the intentional radiator operates below 10 GHz: to the tenth harmonic of the highest fundamental frequency or to 40 GHz, whichever is...

47 CFR 15.209 - Radiated emission limits; general requirements.

Code of Federal Regulations, 2013 CFR

2013-10-01

...) Measurement distance (meters) 0.009-0.490 2400/F(kHz) 300 0.490-1.705 24000/F(kHz) 30 1.705-30.0 30 30 30-88... CISPR quasi-peak detector except for the frequency bands 9-90 kHz, 110-490 kHz and above 1000 MHz...) The provisions in §§ 15.31, 15.33, and 15.35 for measuring emissions at distances other than the...

47 CFR 15.209 - Radiated emission limits; general requirements.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) Measurement distance (meters) 0.009-0.490 2400/F(kHz) 300 0.490-1.705 24000/F(kHz) 30 1.705-30.0 30 30 30-88... CISPR quasi-peak detector except for the frequency bands 9-90 kHz, 110-490 kHz and above 1000 MHz...) The provisions in §§ 15.31, 15.33, and 15.35 for measuring emissions at distances other than the...

47 CFR 15.209 - Radiated emission limits; general requirements.

Code of Federal Regulations, 2014 CFR

2014-10-01

...) Measurement distance (meters) 0.009-0.490 2400/F(kHz) 300 0.490-1.705 24000/F(kHz) 30 1.705-30.0 30 30 30-88... CISPR quasi-peak detector except for the frequency bands 9-90 kHz, 110-490 kHz and above 1000 MHz...) The provisions in §§ 15.31, 15.33, and 15.35 for measuring emissions at distances other than the...

Low-level ultrahigh-frequency and ultrashort-pulse blue laser irradiation enhances osteoblast extracellular calcification by upregulating proliferation and differentiation via transient receptor potential vanilloid 1.

PubMed

Mikami, Risako; Mizutani, Koji; Aoki, Akira; Tamura, Yukihiko; Aoki, Kazuhiro; Izumi, Yuichi

2018-04-01

Low-level laser irradiation (LLLI) exerts various biostimulative effects, including promotion of wound healing and bone formation; however, few studies have examined biostimulation using blue lasers. The purpose of this study was to investigate the effects of low-level ultrahigh-frequency (UHF) and ultrashort-pulse (USP) blue laser irradiation on osteoblasts. The MC3T3-E1 osteoblast cell line was used in this study. Following LLLI with a 405 nm newly developed UHF-USP blue laser (80 MHz, 100 fs), osteoblast proliferation, and alkaline phosphatase (ALP) activity were assessed. In addition, mRNA levels of the osteoblast differentiation markers, runt-related transcription factor 2 (Runx2), osterix (Osx), alkaline phosphatase (Alp), and osteopontin (Opn) was evaluated, and extracellular calcification was quantified. To clarify the involvement of transient receptor potential (TRP) channels in LLLI-induced biostimulation, cells were treated prior to LLLI with capsazepine (CPZ), a selective inhibitor of TRP vanilloid 1 (TRPV1), and subsequent proliferation and ALP activity were measured. LLLI with the 405 nm UHF-USP blue laser significantly enhanced cell proliferation and ALP activity, compared with the non-irradiated control and LLLI using continuous-wave mode, without significant temperature elevation. LLLI promoted osteoblast proliferation in a dose-dependent manner up to 9.4 J/cm 2 and significantly accelerated cell proliferation in in vitro wound healing assay. ALP activity was significantly enhanced at doses up to 5.6 J/cm 2 , and expression of Osx and Alp mRNAs was significantly increased compared to that of the control on days 3 and 7 following LLLI at 5.6 J/cm 2 . The extent of extracellular calcification was also significantly higher as a result of LLLI 3 weeks after the treatment. Measurement of TRPV1 protein expression on 0, 3, and 7 days post-irradiation revealed no differences between the LLLI and control groups; however, promotion of cell

47 CFR 90.719 - Individual channels available for assignment in the 220-222 MHz band.

Code of Federal Regulations, 2010 CFR

2010-10-01

... the 220-222 MHz band. 90.719 Section 90.719 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... Licensing and Use of Frequencies in the 220-222 MHz Band § 90.719 Individual channels available for assignment in the 220-222 MHz band. (a) Channels 171 through 200 are available to both Government and non...

Mechanisms of radiation embrittlement of VVER-1000 RPV steel at irradiation temperatures of (50-400)°C

NASA Astrophysics Data System (ADS)

Kuleshova, E. A.; Gurovich, B. A.; Bukina, Z. V.; Frolov, A. S.; Maltsev, D. A.; Krikun, E. V.; Zhurko, D. A.; Zhuchkov, G. M.

2017-07-01

This work summarizes and analyzes our recent research results on the effect of irradiation temperature within the range of (50-400)°C on microstructure and properties of 15Kh2NMFAA class 1 steel (VVER-1000 reactor pressure vessel (RPV) base metal). The paper considers the influence of accelerated irradiation with different temperature up to different fluences on the carbide and irradiation-induced phases, radiation defects, yield strength changes and critical brittleness temperature shift (ΔTK) as well as on changes of the fraction of brittle intergranular fracture and segregation processes in the steel. Low temperature irradiation resulted solely in formation of radiation defects - dislocation loops of high number density, the latter increased with increase in irradiation temperature while their size decreased. In this regard high embrittlement rate observed at low temperature irradiation is only due to the hardening mechanism of radiation embrittlement. Accelerated irradiation at VVER-1000 RPV operating temperature (∼300 °C) caused formation of radiation-induced precipitates and dislocation loops, as well as some increase in phosphorus grain boundary segregation. The observed ΔTK shift being within the regulatory curve for VVER-1000 RPV base metal is due to both hardening and non-hardening mechanisms of radiation embrittlement. Irradiation at elevated temperature caused more intense phosphorus grain boundary segregation, but no formation of radiation-induced precipitates or dislocation loops in contrast to irradiation at 300 °C. Carbide transformations observed only after irradiation at 400 °C caused increase in yield strength and, along with a contribution of the non-hardening mechanism, resulted in the lowest ΔTK shift in the studied range of irradiation temperature and fluence.

Higher operation temperature quadrant photon detectors of 2-11 μm wavelength radiation with large photosensitive areas

NASA Astrophysics Data System (ADS)

Pawluczyk, J.; Sosna, A.; Wojnowski, D.; Koźniewski, A.; Romanis, M.; Gawron, W.; Piotrowski, J.

2017-10-01

We report on the quadrant photon HgCdTe detectors optimized for 2-11 μm wavelength spectral range and Peltier or no cooling, and photosensitive area of a quad-cell of 1×1 to 4×4 mm. The devices are fabricated as photoconductors or multiple photovoltaic cells connected in series (PVM). The former are characterized by a relatively uniform photosensitive area. The PVM photovoltaic cells are distributed along the wafer surface, comprising a periodical stripe structure with a period of 20 μm. Within each period, there is an insensitive gap/trench < 9 μm wide between stripe mesas. The resulting spatial quantization error prevents positioning of the beam spot of size close to the period, but becomes negligible for the optimal spot size comparable to a quadrant-cell area. The photoconductors produce 1/f noise with about 10 kHz knee frequency, due to bias necessary for their operation. The PVM photodiodes are typically operated at 0 V bias, so they generate no 1/f noise and operation from DC is enabled. At 230 K, upper corner frequency of 16 to 100 MHz is obtained for photoconductor and 60 to 80 MHz for PVM, normalized detectivity D* 6×107 cm×Hz1/2/W to >1.4×108 cm×Hz1/2/W for photoconductor and >1.7×108 cm·Hz1/2/W for PVM, allowing for position control of the radiation beam with submicron accuracy at 16 MHz, 10.6 μm wavelength of pulsed radiation spot of 0.8 mm dia at the close-to-maximal input radiation power density in a range of detector linear operation.

47 CFR 95.1401 - Frequency.

Code of Federal Regulations, 2010 CFR

2010-10-01

... SERVICES Personal Locator Beacons (PLB). § 95.1401 Frequency. The frequency band 406.0-406.1 MHz is an emergency and distress frequency band available for use by Personal Locator Beacons (PLBs). Personal Locator Beacons that transmit on the frequency band 406.0-406.1 MHz must use G1D emission. Use of these...

A research of the propagation of LoRa signals at 433 and 868 MHz in difficult urban conditions

NASA Astrophysics Data System (ADS)

Eremin, V.; Borisov, A.

2018-05-01

The article examines the issue of investigating the propagation of LoRa signals at 433 MHz and 868 MHz in difficult urban conditions. A theoretical calculation was made, which showed that the signal propagation distance is about 1.8 km for the module with a frequency of 433 MHz and about 915 m for the 868 MHz frequency. Experimental studies show that the transmission distance of the 868 MHz module is approximately 660 m, module 433 MHz – 730 m. The discrepancy is due to the influence of interference, which is always present in the modern city, as well as with complex and diverse buildings, which is not taken into account in the parameter SOM when calculating the transmission range.

A sub-μs thermal time constant electrically driven Pt nanoheater: thermo-dynamic design and frequency characterization

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

Ottonello Briano, Floria, E-mail: floria@kth.se; Sohlström, Hans; Forsberg, Fredrik

2016-05-09

Metal nanowires can emit coherent polarized thermal radiation, work as uncooled bolometers, and provide localized heating. In this paper, we engineer the temperature dynamics of electrically driven Pt nanoheaters on a silicon-on-insulator substrate. We present three designs and we electrically characterize and model their thermal impedance in the frequency range from 3 Hz to 3 MHz. Finally, we show a temperature modulation of 300 K while consuming less than 5 mW of power, up to a frequency of 1.3 MHz. This result can lead to significant advancements in thermography and absorption spectroscopy.

High frequency pulsed electromigration

NASA Astrophysics Data System (ADS)

Malone, David Wayne

Electromigration life tests were performed on copper-alloyed aluminum test structures that were representative of modern CMOS metallization schemes, complete with Ti/TiN cladding layers and a tungsten-plug contact at the cathode. A total of 18 electrical stress treatments were applied. One was a DC current of 15 mA. The other 17 were pulsed currents, varied according to duty cycle and frequency. The pulse amplitude was 15 mA (˜2.7 × 10sp6 A/cmsp2) for all treatments. Duty cycles ranged from 33.3% to 80%, and frequencies fell into three rough ranges-100 KHz, 1 MHz, and 100 MHz. The ambient test temperature was 200sp°C in all experiments. Six to 9 samples were subjected to each treatment. Experimental data were gathered in the form of test stripe resistance versus time, R(t). For purposes of lifetime analysis, "failure" was defined by the criterion R(t)/R(0) = 1.10, and the median time to failure, tsb{50}, was used as the primary basis of comparison between test groups. It was found that the dependence of tsb{50} on pulse duty cycle conformed rather well to the so-called "average current density model" for duty cycles of 50% and higher. Lifetimes were less enhanced for a duty cycle of 33.3%, but they were still considerably longer than an "on-time" model would predict. No specific dependence of tsb{50} on pulse frequency was revealed by the data, that is, reasonably good predictions of tsb{50} could be made by recognizing the dominant influence of duty cycle. These findings confirm that IC miniaturization can be more aggressively pursued than an on-time prediction would allow. It is significant that this was found to be true for frequencies on the order of 100 MHz, where many present day digital applications operate. Post-test optical micrographs were obtained for each test subject in order to determine the location of electromigration damage. The pulse duty cycle was found to influence the location. Most damage occurred at the cathode contact, regardless of

47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., 2110-2150 MHz, and 2160-2200 MHz bands. 101.77 Section 101.77 Telecommunication FEDERAL COMMUNICATIONS...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify... a Police licensee, a Fire Licensee, or an Emergency Medical Licensee as defined in § 90.7 of this...

Analysis and design of an ultrahigh temperature hydrogen-fueled MHD generator

NASA Technical Reports Server (NTRS)

Moder, Jeffrey P.; Myrabo, Leik N.; Kaminski, Deborah A.

1993-01-01

A coupled gas dynamics/radiative heat transfer analysis of partially ionized hydrogen, in local thermodynamic equilibrium, flowing through an ultrahigh temperature (10,000-20,000 K) magnetohydrodynamic (MHD) generator is performed. Gas dynamics are modeled by a set of quasi-one-dimensional, nonlinear differential equations which account for friction, convective and radiative heat transfer, and the interaction between the ionized gas and applied magnetic field. Radiative heat transfer is modeled using nongray, absorbing-emitting 2D and 3D P-1 approximations which permit an arbitrary variation of the spectral absorption coefficient with frequency. Gas dynamics and radiative heat transfer are coupled through the energy equation and through the temperature- and density-dependent absorption coefficient. The resulting nonlinear elliptic problem is solved by iterative methods. Design of such MHD generators as onboard, open-cycle, electric power supplies for a particular advanced airbreathing propulsion concept produced an efficient and compact 128-MWe generator characterized by an extraction ratio of 35.5 percent, a power density of 10,500 MWe/cu m, and a specific (extracted) energy of 324 MJe/kg of hydrogen. The maximum wall heat flux and total wall heat load were 453 MW/sq m and 62 MW, respectively.

Design of an 81.25 MHz continuous-wave radio-frequency quadrupole accelerator for Low Energy Accelerator Facility

NASA Astrophysics Data System (ADS)

Ma, Wei; Lu, Liang; Xu, Xianbo; Sun, Liepeng; Zhang, Zhouli; Dou, Weiping; Li, Chenxing; Shi, Longbo; He, Yuan; Zhao, Hongwei

2017-03-01

An 81.25 MHz continuous wave (CW) radio frequency quadrupole (RFQ) accelerator has been designed for the Low Energy Accelerator Facility (LEAF) at the Institute of Modern Physics (IMP) of the Chinese Academy of Science (CAS). In the CW operating mode, the proposed RFQ design adopted the conventional four-vane structure. The main design goals are providing high shunt impendence with low power losses. In the electromagnetic (EM) design, the π-mode stabilizing loops (PISLs) were optimized to produce a good mode separation. The tuners were also designed and optimized to tune the frequency and field flatness of the operating mode. The vane undercuts were optimized to provide a flat field along the RFQ cavity. Additionally, a full length model with modulations was set up for the final EM simulations. Following the EM design, thermal analysis of the structure was carried out. In this paper, detailed EM design and thermal simulations of the LEAF-RFQ will be presented and discussed. Structure error analysis was also studied.

NICER Discovers mHz Oscillations and Marginally Stable Burning in GS 1826-24

NASA Astrophysics Data System (ADS)

Strohmayer, Tod E.; Gendreau, Keith C.; Keek, Laurens; Bult, Peter; Mahmoodifar, Simin; Chakrabarty, Deepto; Arzoumanian, Zaven; NICER Science Team

2018-01-01

To date, marginally stable thermonuclear burning, evidenced as mHz X-ray flux oscillations, has been observed in only five accreting neutron star binaries, 4U 1636-536, 4U 1608-52, Aql X-1, 4U 1323-619 and Terzan 5 X-2. Here we report the discovery with NASA's Neutron Star Interior Composition Explorer (NICER) of such oscillations from the well-known X-ray burster GS 1826-24. NICER observed GS 1826-24 on 9 September, 2017 for a total exposure of about 4 ksec. Timing analysis revealed highly significant oscillations at a frequency of 8.2 mHz in two successive pointings. The oscillations have a fractional modulation amplitude of approximately 3% for photon energies less than 6 keV. The observed frequency is consistent with the range observed in the other mHz QPO systems, and indeed is slightly higher than the frequency measured in 4U 1636-536 below which mHz oscillations ceased and unstable burning (X-ray bursts) resumed. We discuss the mass accretion rate dependence of the oscillations as well as the X-ray spectrum as a function of pulsation phase. We place the observations in the context of the current theory of marginally stable burning and briefly discuss the potential for constraining neutron star properties using mHz oscillations.

14 CFR Appendix E to Part 29 - HIRF Environments and Equipment HIRF Test Levels

Code of Federal Regulations, 2010 CFR

2010-01-01

... following table: Table I.—HIRF Environment I Frequency Field strength(volts/meter) Peak Average 10 kHz-2 MHz 50 50 2 MHz-30 MHz 100 100 30 MHz-100 MHz 50 50 100 MHz-400 MHz 100 100 400 MHz-700 MHz 700 50 700... Environment II Frequency Field strength(volts/meter) Peak Average 10 kHz-500 kHz 20 20 500 kHz-2 MHz 30 30 2...

14 CFR Appendix D to Part 27 - HIRF Environments and Equipment HIRF Test Levels

Code of Federal Regulations, 2010 CFR

2010-01-01

... following table: Table I.—HIRF Environment I Frequency Field strength(volts/meter) Peak Average 10 kHz-2 MHz 50 50 2 MHz-30 MHz 100 100 30 MHz-100 MHz 50 50 100 MHz-400 MHz 100 100 400 MHz-700 MHz 700 50 700... Environment II Frequency Field strength(volts/meter) Peak Average 10 kHz-500 kHz 20 20 500 kHz-2 MHz 30 30 2...

[The ultrastructure of Sertoli cells and spermatogonia in the rats exposed to radiation under conditions of therapeutic and prophylactic application of low-intensity electromagnetic emission].

PubMed

Korolev, Y N; Bobrovnitskii, I P; Geniatulina, M S; Nikulina, L A; Mikhailik, L V

2018-04-09

it has been demonstrated in various experimental studies that radiation exposure produces a negative impact on the processes of spermatogenesis associated with the disturbances of the microcirculation processes in the testes and the development of cellular and intracellular disintegration expressed as destructive changes in the cells leading to their death. The objective of the present study was to detect the ultrastructural abnormalities in the cells of Sertoli and spermatogonia under conditions of their exposure to radiation and to identify the peculiarities of their regeneration under the influence of the therapeutic and prophylactic application of low-intensity ultra-high frequency (UHF) electromagnetic radiation (EMR) and low-intensity low-frequency magnetic field (MF). The experiments were carried out on 28 non-pedigree mature male rats with the body weight 180-220 g that were divided into four groups. The first study group was comprised of the animals exposed to radiation followed by the application of low-intensity ultra-high frequency UHF electromagnetic radiation EMR. The rats in the second study group experienced effects of radiation and low-intensity low-frequency MF. The animals of the third (control) group were exposed to radiation alone, and those comprising the fourth group 1 (only radiation exposure) were considered to be intact. The studies with the use of electron microscopy showed that the therapeutic and prophylactic application of low-intensity ultra-high frequency (UHF) electromagnetic radiation and low-intensity low-frequency magnetic field caused the decrease in the number and the severity of post-radiation defects in the treated cells together with the increase of the number and size of mitochondria as well as hyperplasia of ribosomes; moreover, it promoted cellular and intracellular regeneration. UHF electromagnetic radiation had a more pronounced stimulating effect on the regeneration processes as compared with low-frequency MF

Laser frequency multiplication

NASA Astrophysics Data System (ADS)

1991-11-01

A high quality mode locked pulse train was obtained at 9.55 microns, the CO2 wavelength chosen for frequency doubling into the atmospheric window at 4.8 microns. The pulse train consists of a 3 micro sec burst of 1.5 nsec pulses separated by 40 nsec, in a TEM (sub 00) mode and with a total energy of 100 mJ. The pulse intensity without focussing is about 3 MW/sq.cm., already quite close to the target intensity of 10 MW/sq.cm. for frequency doubling in a AgGaSe2 crystal. The mode-locked train is obtained by intracavity modulation at 12.5 MHz using a germanium crystal driven with a power of about 30 Watts. Line selection is achieved firstly by the use of a 0.92 mm thick CaF2 plate at the Brewster angle within the cavity, which completely suppresses 10.6 micron band radiation. Secondly, a particular rotational line, the P20 at 9.55 micron, is selected by the injection of a continuous beam is mode-matched to the pulsed laser cavity using a long focal length lens, and for best line-locking it is necessary to fine tune the length of the pulsed laser resonator. Injection causes substantial depression of the gain switched spike.

Realization of a mW-level 10.7-eV (λ = 115.6 nm) laser by cascaded third harmonic generation of a Yb:fiber CPA laser at 1-MHz.

PubMed

Zhao, Zhigang; Kobayashi, Yohei

2017-06-12

We demonstrate a 10.7-eV (λ = 115.6 nm) laser with mW levels of average power and a 1-MHz repetition rate, which was driven by the third harmonic radiation (THG), at 347 nm, of an Yb:fiber chirped pulse amplifier (CPA) laser. The 347 nm ultraviolet radiation was obtained by frequency conversion of the high power output of a 1-MHz Yb:fiber CPA, using beta barium borate (BBO) nonlinear crystals. The frequency converted output was focused down into a gas cell filled with a mixture of Ar and Xe, and was subjected to a second THG frequency conversion. The generated 10.7-eV laser was separated from the fundamental beam using a LiF prism and no further separation from other harmonic waves was required. The highest measured output power was ~80 μW, which corresponded to an average power of ~1.25 mW inside the gas cell when the transmission coefficients of the LiF optics were taken into account. The corresponding conversion efficiency from 347 nm down to 115.6 nm was ~2.5 × 10 -4 .

RTE: A UNIX library with on-line documentation and sample programs for microwave radiative transfer calculations

NASA Astrophysics Data System (ADS)