scholarly journals An Analysis of Pulsar Nulling Statistics

1992 ◽  
Vol 128 ◽  
pp. 265-270
Author(s):  
James D. Biggs
Keyword(s):  
Wide Band ◽  
Emission Mechanism ◽  
Frequency Range ◽  
Pulse Period ◽  
Pulse Profile ◽  
Pulsar Emission ◽  
Rotation Axes ◽  
Upper Limit ◽  
The Mean ◽  
Explicit Correlation

AbstractWe have sought correlations between the fraction of null pulses with other pulsar parameters for an ensemble of 72 pulsars using survival analysis methods. The strongest correlation was found between the null fraction and pulse period. Correlations were also found between other parameters that typically have strong dependencies on pulse period, and this tends to indicate that the null fraction increases with age as was first suggested by Ritchings (1976). However, no explicit correlation was found between pulsar characteristic age and null fraction. A significant anti-correlation was found between the angle subtended by the magnetic and rotation axes and the null fraction.Many of the pulsars presented here were found to null. In particular, all pulse profile classes in the scheme devised by Rankin (1983a) have members that null. Differences in the mean age of these pulsar classes are not very pronounced, and the influence of class on pulse nulling statistics is probably less than that suggested by Rankin (1986), but cannot entirely be ruled out. Also, there is considerable variation in the fraction of null pulses from pulsars within each class, but generally class St pulsars null the least. Of special note is the fact that two pulsars PSR 0833-45 and PSR 1556-44 apparently do not null. The upper limit for PSR 0833–45 is quite low; no nulls were detected in observations of over 120,000 pulses.The similarity of the nulling parameters of pulsars observed at two frequencies near 400 MHz and 843 MHz suggests that the pulsar emission mechanism is wide band over this frequency range.

The Magnetic Pole Model for Pulsar Emission

1978 ◽  
Vol 3 (3) ◽  
pp. 200-205 ◽  
Author(s):  
R. N. Manchester
Keyword(s):  
Duty Cycle ◽  
Pulse Train ◽  
Pole Model ◽  
Magnetic Pole ◽  
Pulse Profile ◽  
Pulsar Emission ◽  
Periodic Pulse ◽  
The Mean

Pulsars are unique astronomical objects in that their emission is in the form of a periodic pulse train. For most pulsars the pulse duty cycle is small, only a few per cent of the period. The shapes and intensities of individual pulses are in general quite variable. This is illustrated in Figure 1 which shows a series of individual pulses from PSR 1133 + 16. Despite this variation in shape of individual pulses, it is found that the mean or integrated pulse profile obtained by adding many pulses synchronously with the period is in most cases stable in shape.

An Analysis of Vocal Communication in the Adult Brown Noddy (Anous stolidus)

The Auk ◽  
1986 ◽  
Vol 103 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Diane E. Riska
Keyword(s):  
Vocal Communication ◽  
Wide Band ◽  
Basic Unit ◽  
Frequency Range ◽  
Mean Frequency ◽  
Dry Tortugas ◽  
Msec Duration ◽  
Vocal Signals ◽  
The Mean ◽  
Nesting Season

Abstract I analyzed vocal signals of marked adult Brown Noddies (Anous stolidus) throughout their nesting season in the Dry Tortugas, Florida from 1979 to 1982. The basic unit of the adult repertoire is a wide-band click, less than 4 msec duration, ranging in frequency from 200 to 3,300 Hz. I identified nine temporal arrangements of these clicks, which form the notes of the calls. These calls differ little in frequency range, but they differ in the mean frequency of the most intense sound energy band, in note duration, in the number of clicks per note, and in internote interval. These calls are used in different contexts, which sometimes overlap. Frequency, note duration, and internote interval do not differ between sexes. Mean frequency and note length varied among individuals for some calls. No tonal elements characteristic of calls of Brown Noddy nestlings remain in the adult repertoire.

scholarly journals Multi Radio Frequency Observations of Pulsars

1981 ◽  
Vol 95 ◽  
pp. 177-185
Author(s):  
Norbert Bartel
Keyword(s):  
Radio Emission ◽  
Frequency Dependence ◽  
Coherence Time ◽  
List Type ◽  
Focal Points ◽  
Type Number ◽  
Emission Mechanism ◽  
Frequency Range ◽  
Pulsar Emission ◽  
Points Of Interest

An investigation of the frequency dependence of the radio emission of pulsars promises to contribute considerably to the understanding of such outstanding questions as: 1.Is the emission mechanism narrowband or broadband?2.What is the coherence time of the radiation?3.Does a radius-to-frequency mapping exist?4.Is pulsed radiation absorbed in the magnetosphere?The 100-m telescope in Effelsberg is satisfactorily sensitive in the GHz frequency range so that we could observe averaged pulses up to 22.7 GHz (Bartel et al., 1977; Bartel et al., 1978) and single pulses at 8.8 GHz (Bartel et al., 1980a), which are the highest radio frequencies respectively at which pulsars have been detected. Therefore quite naturally the analysis of the frequency dependent pulsar emission became one of the focal points of interest in pulsar research at the MPIfR.

Microwave wide band absorption by carbon from Corn cob-1

2016 ◽  
Vol 12 (2) ◽  
pp. 4204-4212 ◽  
Author(s):  
Maheshwar Sharon ◽  
Ritesh Vishwakarma ◽  
Abhijeet Rajendra Phatak ◽  
Golap Kalita ◽  
Nallin Sharma ◽  
...  
Keyword(s):  
Microwave Absorption ◽  
Agricultural Waste ◽  
Wide Band ◽  
Nickel Nitrate ◽  
Equivalent Amount ◽  
Frequency Range ◽  
Corn Cob ◽  
Different Temperatures ◽  
Band Absorption ◽  
5 Ghz

Corn cob, an agricultural waste, is paralyzed at different temperatures (700oC, 800oC and 900oC). Microwave absorption of carbon in the frequency range of 2 GHz to 8 GHz is reported. Carbon activated  with 5%  nickel nitrate showed more than 90% absorption of microwave in the frequency range from 6 GHz to 8 GHz, while carbon activated  with 10% Nickel nitrate treated corn cob showed 90% absorption  in the frequency range of 2.5 GHz to 5 GHz. Carbon showing the best absorption are characterized by XRD, Raman spectra and SEM . It is suggested that corn cob treatment   alone with KOH did not improve the microwave absorption, whereas treatment along with nickel nitrate improved the absorption property much better. It is proposed that treatment with nickel nitrate helps in creating suitable pores in carbon   which improved the absorption behavior because while treating carbon with 1N HCl helps to leach out nickel creating equivalent amount of pores in the carbon.

scholarly journals Band notched self complementaryultra wideband antenna for wireless applications

2018 ◽  
Vol 7 (2.8) ◽  
pp. 529 ◽  
Author(s):  
Ch Ramakrishna ◽  
G A.E.Satish Kumar ◽  
P Chandra Sekhar Reddy
Keyword(s):  
High Frequency ◽  
Return Loss ◽  
Wide Band ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Relative Dielectric Permittivity ◽  
Frequency Range ◽  
Ground Structure ◽  
Wireless Applications ◽  
Patch Edge

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton  substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz,  band rejected WLAN frequency range 5.6-6.5 GHz with  vswr is less than 2.

Stationary and Transient Response of Cylindrical Shells Under Random Excitation

1988 ◽  
Vol 110 (2) ◽  
pp. 205-209
Author(s):  
A. V. Singh
Keyword(s):  
Transient Response ◽  
Random Vibration ◽  
Time History ◽  
Wide Band ◽  
Random Excitation ◽  
Mode Shapes ◽  
The Finite Element Method ◽  
History Of ◽  
The Mean ◽  
Random Vibration Analysis

This paper presents the random vibration analysis of a simply supported cylindrical shell under a ring load which is uniform around the circumference. The time history of the excitation is assumed to be a stationary wide-band random process. The finite element method and the condition of symmetry along the length of the cylinder are used to calculate the natural frequencies and associated mode shapes. Maximum values of the mean square displacements and velocities occur at the point of application of the load. It is seen that the transient response of the shell under wide band stationary excitation is nonstationary in the initial stages and approaches the stationary solution for large value of time.

An Electrophysiological Measure of Temporal Resolution in Normal Subjects Using Frequency Modulated Signals

2002 ◽  
Vol 11 (1) ◽  
pp. 42-49
Author(s):  
Devin L. McCaslin ◽  
Lawrence L. Feth ◽  
Gary P. Jacobson ◽  
Pamela J. Mishler
Keyword(s):  
Temporal Resolution ◽  
Mismatch Negativity ◽  
Normal Subjects ◽  
Single Step ◽  
Event Related Potential ◽  
Frequency Range ◽  
Temporal Properties ◽  
Step Duration ◽  
The Mean ◽  
Modulated Signals

This investigation was conducted to determine whether an exogenous event-related potential called the mismatch negativity (MMN) would change systematically in response to frequency-modulated signals with varying temporal properties. Both N1 and P2 waveforms were recorded for 50-ms frequency-modulated signals from normal hearing listeners. The standard stimuli for this investigation were continuous sweep tones with center frequencies of 1000 Hz that traversed a frequency range of 200 Hz in a single step. The rare stimuli were signals that traversed the same frequency range in two, four, six, or eight discrete steps. Results suggest that for the 10 participants, 1) the mean MMN peak-to-peak amplitude and mean area decreased significantly with decreases in step duration, 2) MMN area amplitude was the best indicator of psychophysical performance for the two magnitude measures, and 3) MMN onsets and peak latencies did not show either a significant increase or decrease in latency as step duration decreased.

Prolactin Screening in a Cohort of Schizophrenia Patients in Birmingham

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
I. Waheed ◽  
A. Khan
Keyword(s):  
Health Centre ◽  
Drug Dosage ◽  
Oral Risperidone ◽  
Clinical Symptomatology ◽  
Upper Limit ◽  
Routine Monitoring ◽  
Current Medication ◽  
The Mean ◽  
Unselected Group

Aim:To establish the numerical prevalence and severity of raised prolactin levels in patients apparently asymptomatic.Method:All outpatients with schizophrenia receiving antipsychotics at Small Heath Health Centre had routine annual prolactin measurements. the sampling was done 0900-1300 either in clinic or at patient's homes. the Upper Limit of Normal (ULN) for prolactin was set by the hospital pathology service at 324 mIU/L (males) and 496 mIU/L (females). Sampling was done 0900-1200 either in clinic or at patient's homes. We recorded the patient's name, age, unit number, ethnicity, details of current medication, recent changes to medication and symptoms of hyperprolactinaemia.Results:Prolactin levels were obtained for 43 patients (M: 24 F:19). All of these patients had no clinical symptomatology that had led to prolactin measurements previously. Abnormal values were found in 47 per cent of females and 58 per cent of males, or 56 per cent (n=24) of the whole cohort. the mean prolactin was 789 mIU/L with a mean of 497 mIU/L in males and 1100 mIU/L in females. All patients on oral risperidone had hyperprolactinaemia.Conclusion:Routine prolactin screening showed abnormal values in 56 per cent of patients and significantly abnormal levels (>1000 mIU/L) that should lead to consideration of drug/dosage alterations in 26% of patients. the prevalence of hyperprolactinaemia in an unselected group of outpatients with schizophrenia suggests that consideration may be given to routine monitoring.

Topographic Analysis of Steady-State Visual Evoked Potentials (SVEPs) in The Medium Frequency Range in Migraine With and Without Aura

Cephalalgia ◽  
1992 ◽  
Vol 12 (4) ◽  
pp. 244-249 ◽  
Author(s):  
Franco M Puca ◽  
Marina de Tommaso ◽  
Maria A Savarese ◽  
Sergio Genco ◽  
Addolorata Prudenzano
Keyword(s):  
Steady State ◽  
Frequency Range ◽  
Medium Frequency ◽  
Topographic Analysis ◽  
Absolute Power ◽  
Interhemispheric Coherence ◽  
The Mean ◽  
Student’S T ◽  
Medium Frequency Range ◽  
Student’S T Test

Topographic analysis of SVEPs in the medium frequencies range was performed in 30 migraineurs without aura, 20 migraineurs with aura and in 20 control subjects. The mean absolute power values of the fundamental component F1, the subharmonic F1/2 and the first harmonic F2, corrected by logarithmic transformation, were computed in each group and then compared using Student's t-test. The interhemispheric coherence of the F1 component was also evaluated. The 18, 21 and 27 Hz F1 components were increased in both migraineurs with and without aura, particularly in the temporo-parietal regions. The 24 Hz F1 component was augmented only in migraineurs without aura in the parieto-occipital regions in comparison with migraineurs with aura and controls. Migraine with aura patients had a reduced interhemispheric coherence mostly of 12 Hz and 15 Hz F1 components in frontal and temporo-parietal regions. Results of the study confirm abnormalities of SVEPs in migraineurs with and without aura. These consist of widespread increases of F1 components in the medium frequency range over the temporo-parietal regions.

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