Ion-cyclotron modes in weakly relativistic plasmas

1994 ◽  
Vol 51 (3) ◽  
pp. 371-379 ◽  
Author(s):  
Chandu Venugopal ◽  
P. J. Kurian ◽  
G. Renuka
Keyword(s):  
Dispersion Relation ◽  
High Frequency ◽  
Low Frequency ◽  
Dispersion Relations ◽  
The Other ◽  
Larmor Radius ◽  
Relativistic Plasmas ◽  
Ion Plasma ◽  
Maxwellian Plasma ◽  
Relativistic Dispersion

We derive a dispersion relation for the perpendicular propagation of ioncyclotron waves around the ion gyrofrequency ω+ in a weaklu relaticistic anisotropic Maxwellian plasma. These waves, with wavelength greater than the ion Larmor radius rL+ (k⊥ rL+ < 1), propagate in a plasma characterized by large ion plasma frequencies (). Using an ordering parameter ε, we separated out two dispersion relations, one of which is independent of the relativistic terms, while the other depends sensitively on them. The solutions of the former dispersion relation yield two modes: a low-frequency (LF) mode with a frequency ω < ω+ and a high-frequency (HF) mode with ω > ω+. The plasma is stable to the propagation of these modes. The latter dispersion relation yields a new LF mode in addition to the modes supported by the non-relativistic dispersion relation. The two LF modes can coalesce to make the plasma unstable. These results are also verified numerically using a standard root solver.

P3392Potential of imaging-guided PCI for event suppression in Japanese acute myocardial infarction patients: J-MINUET substudy

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
T Yamashita ◽  
K Sakamoto ◽  
K Tsujita ◽  
K Nakao ◽  
Y Ozaki ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
High Frequency ◽  
Low Frequency ◽  
The Other ◽  
Intravascular Imaging ◽  
Clinical Events ◽  
Coronary Imaging ◽  
Usage Frequency ◽  
Moderate Frequency ◽  
Event Rates

Abstract Background Intravascular ultrasound (IVUS) and Optical Coherence Tomography (OCT) has been widely used in clinical settings. Although favorable results of imaging-guided percutaneous coronary intervention (PCI) compared with angio-guided PCI were observed in several studies, impacts of institutional-based usage frequency, about imaging-guided PCI, have not been well elucidated. Methods To elucidate the impact of imaging-guided PCI and the effects of frequency of its usage, we analyzed data of the Japanese registry of acute Myocardial INfarction diagnosed by Universal dEfiniTion (J-MINUET). This was a prospective and multicenter registry consisting of 3,283 AMI patients, who were hospitalized within 48 hours of onset from July 2012 to March 2014. Clinical follow-up data was obtained for 3 years. In this sub-study, a total of 2,788 patients who underwent urgent PCI having detailed procedural information were enrolled. We analyzed the differences of utilization rates of imaging-guided PCI among the participating institutions and the impacts for the clinical events. The participating institutions were divided into 3 groups by the frequency of IVUS usage: low frequency institutions: under 50%; moderate frequency institutions: 50% to 90%; and, high frequency institutions: over 90%. Results In this cohort registry, patients were enrolled from 28 institutions. The utilization rate of coronary imaging varied widely depending on each institution from 15.4% to 100% (mean 85.7%±24.3, median 97.4%). When the institutions were divided into 3 groups by the frequency of intravascular imaging usage, four low frequency institutions enrolled 295 patients, five moderate frequency institutions enrolled 624 patients, and 19 high frequency institutions enrolled 1,491 patients. Although the incidence of MACE (death, MI, stroke, cardiac failure, or revascularization for unstable angina) decreased stepwise (33.2%, 23.7%, and 19.7%) (gray bar in the Figure), the event rates of the imaging-guided PCI cases among the 3 groups were comparable (21.6%, 21.9%, and 19.6%) (white bar in the Figure). On the other hand, a gradual event reduction between the 3 groups was observed in the angio-guided PCI cases (black bar in the Figure). In comparison of MACE rate between imaging-guided and angio-guided PCI, there were statistically significant differences in the low frequency and moderate frequency institutions (p=0.001 and p=0.012, respectively). In contrast, comparable event rates were observed in the high frequency institutions (p=0.441). MACE rate by imaging usage frequency Conclusions In Japanese ACS patients treated with imaging-guided PCI, better suppression of clinical events during 3-year was found in the institutions with the more frequent use of intravascular imaging, mainly due to stepwise event suppression in the cases of angio-guided PCI. On the other hand, the clinical benefit of coronary imaging was obtained independently of the frequency of use and its experience.

scholarly journals Optimizing smoke alarm signals: Testing the effectiveness of children’s smoke alarms for sleeping adults

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Gary A. Smith ◽  
Sandhya Kistamgari ◽  
Mark Splaingard
Keyword(s):  
Median Time ◽  
High Frequency ◽  
Low Frequency ◽  
The Other ◽  
Wilcoxon Test ◽  
Smoke Alarm ◽  
Smoke Alarms ◽  
Alarm Signals ◽  
Frequency Tone ◽  
Residential Fire

Abstract Background Being asleep is an important risk factor for death during a residential fire; however, the high-frequency tone smoke alarms in many homes will not adequately awaken children who are old enough to self-rescue. In a series of previous studies, we identified smoke alarm signals that effectively awaken children 5–12 years old and prompt their escape. Because it is impractical to have separate alarms for children and adults in a household, the purpose of this study is to test whether alarms that are effective in awakening children and prompting their escape are also effective among adults. Methods Using a randomized, non-blinded, repeated measures design, 150 adults 20–49 years old were exposed during stage 4 sleep to four different smoke alarms. Statistical tests included the Kaplan-Meier estimator, generalized Wilcoxon test, and hazard ratios with Wald’s 95% confidence intervals. Results The median age of study subjects was 30.0 years and 67.3% were female. Almost all (n = 149) subjects awakened and performed the escape procedure to all four alarms; one individual did not awaken or escape to the high-frequency tone alarm. The median time-to-awaken was 2.0 s for the high-frequency tone alarm and 1.0 s for the other three alarms. The median time-to-escape for the high-frequency tone alarm was 12.0 s, compared with 10.0 s for the low-frequency tone alarm and 9.0 s each for the female and male voice alarms. All pairwise comparisons between the high-frequency tone alarm and each of the other three alarms were statistically significant for the probability functions for time-to-awaken and time-to-escape. There were no significant differences in these outcome measures between the latter three alarms, except for female voice versus low-frequency tone alarms for time-to-escape. Conclusions All alarms performed well, demonstrating that smoke alarms developed for the unique developmental requirements of sleeping children are also effective among sleeping adults. Compared with a high-frequency tone alarm, use of these alarms may reduce residential fire-related injuries and deaths among children, while also successfully alerting adult members of the household.

Stability of anisotropic plasmas to almost-perpendicular magnetosonic waves

1971 ◽  
Vol 6 (3) ◽  
pp. 495-512 ◽  
Author(s):  
R. W. Landau† ◽  
S. Cuperman
Keyword(s):  
Magnetic Field ◽  
Dispersion Relation ◽  
Simple Form ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Alfven Wave ◽  
Larmor Radius ◽  
Ion Plasma ◽  
The Stability ◽  
The Magnetic Field

The stability of anisotropic plasmas to the magnetosonic (or right-hand compressional Alfvén) wave, near the ion cyclotron frequency, propagating almost perpendicular to the magnetic field, is investigated. For this case, and for wavelengths larger than the ion Larmor radius and for large ion plasma frequency (w2p+ ≫ Ωp+) the dispersion relation is obtained in a simple form. It is shown that for T # T' (even T ≫ T) no instabifity occurs. The resonant ters are also included, and it is shown that there is no resonant instabifity, only damping.

scholarly journals THE AGRO-PASTORAL CONFLICTS AND FORAGE SPECIES PRIZED BY CATTLE: CASE OF THE NORTHERN PERIPHERY OF THE MBAM AND DJEREM NATIONAL PARK (ADAMAOUA-CAMEROON)

2021 ◽  
Vol 9 (02) ◽  
pp. 965-985
Author(s):  
Marie Mvu Njoya ◽  
◽  
Ambahe Duplex Rufin ◽  
Keyword(s):  
High Frequency ◽  
National Park ◽  
Low Frequency ◽  
Partial Solution ◽  
The Other ◽  
Survey Method ◽  
Other Hand ◽  
Forage Species ◽  
The One ◽  
The Relationship

In the outskirts of the northern periphery of Mbam and Djerem National Park, agro-pastoral conflicts have become very frequent in recent years. The resulting damage is so surprising that it leaves no one indifferent. Unfortunately, many writings analyze the causes of these agro-pastoral conflicts without, however, dwelling on the fodder resources which constitute not only the staple food of cattle but also one of the primary factors of these antagonisms. To overcome this knowledge gap, the authors adopted the survey method in order to identify, on the one hand, the attributes of agro-pastoral conflicts and the plant species consumed in all seasons by cattle on the northern periphery of the PNMD and, on the other hand, the relationship between these forage species with the frequency of agro-pastoral conflicts according to the protagonists and the seasons. Thus, from field observations and a questionnaire sent to 44 breeders and 103 farmers in four control villages, it results, after processing the data, that the high frequency of conflicts experienced by the farmers in the dry season (35.9 %) and especially by the breeders (70.5%) is due to the location of the forage species prized in this season at the bottom of the valleys where the herds are concentrated and compete. On the other hand, the low frequency of conflicts experienced during the rainy season especially by breeders, except in Mbitom, is more justified by the extension of fodder registers to woody leaves from the start of this season. Finally, the fodder fields of Brachiaria constitute a partial solution to the shortage of pastures even if it sometimes gives rise to new conflicts between herders.

Stability of relativistic anisotropic plasmas to perpendicular magnetosonic waves

1970 ◽  
Vol 4 (3) ◽  
pp. 495-510 ◽  
Author(s):  
R. W. Landau ◽  
S. Cuperman
Keyword(s):  
Dispersion Relation ◽  
Cyclotron Frequency ◽  
Plasma Frequency ◽  
Interplanetary Medium ◽  
Alfven Wave ◽  
Larmor Radius ◽  
First Order ◽  
Ion Plasma ◽  
The Stability ◽  
The Magnetic Field

The stability of relativistic anisotropic plasmas to the magnetosonic (or righthand compressional Alfvén) wave, near the ion cyclotron frequency, propagating perpendicular to the magnetic field, is investigated. For this case, and for wavelengths larger than the ion Larmor radius and large ion plasma frequency () the dispersion relation is obtained in a simple form and solved. It is shown that for T‖ ╪ T⊥ (even T‖ ≥ T⊥) no instability occurs. This conclusion applies also to the case of the anisotropic interplanetary medium.We note a peculiarity of the dispersion relation. Zero-order and first-order terms cancel so that the relation is of second order in our expansion parameter. The non-relativistic numerical results of Fredricks and Kennel are recovered.

Existence of Dominant Players and their Role in the Formation of a Cabinet Coalition

2017 ◽  
Vol 19 (01) ◽  
pp. 1750005
Author(s):  
Artyom Jelnov
Keyword(s):  
Empirical Evidence ◽  
High Frequency ◽  
Winning Coalition ◽  
Low Frequency ◽  
The Other ◽  
Dominant Party ◽  
Frequency Occurrence

A party is dominant if there is a majority coalition to which that party belongs such that it affords this party more possibilities to form an alternative winning coalition than any of the other members of the coalition. I present empirical evidence showing that an allocation of seats in a parliament is biased toward the high frequency occurrence of a dominant party and the low frequency occurrence of a dictator. If a dominant party forms a cabinet coalition, and if that cabinet coalition has a majority in parliament, then the dominant party tends to form a coalition which it dominates.

scholarly journals Modifikasi Permukaan Elemen Peredam Bising Dengan Profil Berbentuk Prisma

2016 ◽  
Vol 6 (01) ◽  
Author(s):  
Hanif Azimut
Keyword(s):  
High Frequency ◽  
Sound Absorption ◽  
Coupling Effect ◽  
Low Frequency ◽  
The Other ◽  
Frequency Range ◽  
Closed Type ◽  
Wave Resonance ◽  
Half Wave ◽  
Absorption Performance

<p class="AbstractText">The influence of surface modification by using prism shaped profile on the sound absorption of absorber element was investigated experimentally. A prime number based configuration of the two types opened and closed type rism shaped profile inclusion was tested by using impedance tube according ASTM E1050 standard. The result shows that sound absorption at low frequency band below 200 Hz increased with the increasing of closed prism number. It is related to the coupling effect between the cavities of the absorber element and the prisms that changes reactance of the coupled structure. In the other side, a half wave resonance like effect occur on the use of opened prisms inclusion, which is increase the sound absorption performance at mid to high frequency range between 800 Hz to 1,25 kHz.  </p>

Identification of Voiceless Fricatives by High Frequency Hearing Impaired Listeners

1969 ◽  
Vol 12 (2) ◽  
pp. 426-434 ◽  
Author(s):  
Donald L. Lawrence ◽  
Vincent W. Byers
Keyword(s):  
High Frequency ◽  
Energy Intensity ◽  
Low Frequency ◽  
Hearing Impaired ◽  
The Other

Identification of voiceless fricatives was investigated in five subjects having steep hearing losses above 1000 Hz. Sixteen consonant-vowel test syllables were formed by combining each of the voiceless fricatives /s, ∫, f, θ/ with the vowels /i, e, o, u/. The fricatives were identified correctly as follows: /∫/ 87%; /s/ 83%; /f/ 77%; and /θ/ 72%. Subjects showed idiosyncratic fricative confusion patterns. Confusions of the fricatives generally divided into two groups: /s/ and /∫/ were confused one for the other, and /f/ and /θ/ one for the other. There were no vowel confusions; however, the fricatives were more often confused in association with the front vowels, /i/ and /e/, than with the back vowels, /u/ and /o/. Examination of the fricative syllables suggests that low frequency energy, intensity, and duration of the fricative sounds, as well as formant transitions of vowels are available to these subjects to serve as possible cues for voiceless fricative identification.

scholarly journals High resolution VLBI observations of the nuclei of bright galaxies and quasars at 327 MHz

1986 ◽  
Vol 119 ◽  
pp. 169-170
Author(s):  
S. Ananthakrishnan ◽  
V.K. Kulkarni
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
The Other ◽  
Radio Sources ◽  
Interplanetary Scintillation ◽  
Ss 433 ◽  
Vlbi Observations ◽  
Nearby Galaxies ◽  
Compact Sources ◽  
3C 120

An intercontinental VLBI experiment at 327 MHz involving the Ooty Radio Telescope and telescopes at Jodrell Bank, Westerbork, Torun and Crimea was carried out during December 8–12, 1983. The purpose of the experiment was to (i) establish the feasibility of performing MKII VLBI observations from India and (ii) to study the low frequency structure of nearby galaxies, quasars and some other well known radio sources at metre wavelengths. The sources observed were NGC 262, 315, 1052, 1068, 1265, 1275, 4151, 4486, 7674 and 3C 120; PKS 1055+018, 1148−001 and CTA 102; 3C 237 and SS 433. The bright NGC galaxies chosen were selected from an Interplanetary Scintillation survey of 150 nearby galaxies (Bagri and Ananthakrishnan 1983); they were found to have a flux density greater than about 0.2 Jy in subarcsec components at 327 MHz and have high frequency VLBI observations. The quasars chosen are amongst the most compact sources known at metrewavelengths. The other objects were the well known sources which have been studied extensively at higher frequencies.

Low-frequency drift-induced instabilities in a magnetized two-ion plasma

1986 ◽  
Vol 35 (3) ◽  
pp. 393-412 ◽  
Author(s):  
R. Bharuthram ◽  
M. A. Hellberg
Keyword(s):  
Dispersion Relation ◽  
Numerical Solutions ◽  
Cyclotron Frequency ◽  
Low Frequency ◽  
Frequency Drift ◽  
Transition Diagram ◽  
Electrostatic Waves ◽  
Ion Plasma ◽  
Parameter Values ◽  
A Current

Numerical solutions of a dispersion relation for low-frequency electrostatic waves in a current-carrying, cold, weakly collisional, magnetized two-ion plasma are used to discuss the two-stream and resistive natures of the ion-ion hybrid instability. An instability with analogous behaviour is found to be associated with the light ion cyclotron frequency. Analytical results explain the behaviour. A numerically derived transition diagram summarizes the parameter values for which transitions between different modes take place.

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