scholarly journals Observations of Giant Pulses from Pulsar PSR B1937+21

1996 ◽  
Vol 160 ◽  
pp. 209
Author(s):  
S. E. Thorsett ◽  
J. A. Shrauner ◽  
I. Cognard ◽  
J. H. Taylor
Keyword(s):  
Power Law ◽  
Millisecond Pulsar ◽  
Power Law Distribution ◽  
Sampling System ◽  
Giant Pulse ◽  
Circularly Polarized ◽  
Giant Pulses ◽  
Interstellar Scattering ◽  
The Mean ◽  
The Individual

AbstractWe discuss observations of giant pulses from the millisecond pulsar PSR B1937+21 at 430 MHz, with a baseband sampling system at Arecibo (Shrauner et al., these proceedings) and coherent dedispersion techniques. About one pulse or interpulse per hundred thousand is stronger than 100 times the mean flux density, and the giant pulse strengths follow a power law distribution somewhat shallower than that of the Crab giant pulses. The individual giant pulses appear consistent with impulses shorter than a few microseconds, convolved with an exponential due to interstellar scattering. They are systematically delayed with respect to the average emission, and many are nearly 100% circularly polarized.

scholarly journals Detection of Giant pulses from pulsar PSR B0950+08

2012 ◽  
Vol 8 (S291) ◽  
pp. 502-504
Author(s):  
T. V. Smirnova
Keyword(s):  
Distribution Function ◽  
Flux Density ◽  
Power Law ◽  
Pulse Energy ◽  
Cumulative Distribution Function ◽  
Cumulative Distribution ◽  
Maximum Peak ◽  
Giant Pulses ◽  
Peak Flux ◽  
The Mean

AbstractWe investigated pulse intensities of PSR B0950+08 at 112 MHz at various longitudes (phases) and detected very strong pulses exceeding the amplitude of the mean profile by more than one hundred times. The maximum peak flux density of a recorded pulse is 15240 Jy, and the energy of this pulse exceeds the mean pulse energy by a factor of 153. The analysis shows that the cumulative distribution function (CDF) of pulse intensities at the longitudes of the main pulse is described by a piece-wise power law, with a slope changing from n=−1.25 ± 0.04 to n=−1.84 ± 0.07 at I≥600 Jy. The CDF for pulses at the longitudes of the precursor has a power law with n=−1.5 ± 0.1. Detected giant pulses from this pulsar have the same signature as giant pulses of other pulsars.

scholarly journals Giant Pulses — A Brief Review

2004 ◽  
Vol 218 ◽  
pp. 315-318
Author(s):  
Simon Johnston ◽  
Roger W. Romani
Keyword(s):  
Power Law ◽  
High Energy ◽  
Giant Pulse ◽  
Pulse Emission ◽  
Energy Emission ◽  
Giant Pulses ◽  
Definition Of ◽  
High Energy Emission

We briefly review observational manifestations of pulsars with giant pulse emission and consider quasi-giant pulse phenomena in other pulsars. We argue that power-law statistics give the best definition of giant pulses. Finally, we speculate as to the origin of the giant pulses and a possible link with high energy emission.

scholarly journals High use of the emergency department shows typical features of complex systems: analysis of multicentre linked data

2020 ◽  
Author(s):  
Christopher Burton ◽  
Tony Stone ◽  
Phillip Oliver ◽  
Jon M Dickson ◽  
Jen Lewis ◽  
...  
Keyword(s):  
Complex Systems ◽  
Power Law ◽  
Systems Analysis ◽  
Likelihood Estimation ◽  
Power Law Distribution ◽  
Health Records ◽  
One Year ◽  
The Individual ◽  
The Uk ◽  
Power Law Distributions

ABSTRACTObjectiveHigh use of the ED is a worldwide problem. We hypothesised that high use of the ED could be understood as a feature of a complex system comprising patients, healthcare and society. Complex systems have characteristic statistical properties, with stable patterns at the level of the system emerging from unstable patterns at the level of individuals who make up the system.MethodsAnalysis of a linked dataset of routinely collected health records from all 13 hospital trusts providing ED care in the Yorkshire and Humber region of the UK (population 5.5 million). We analysed the distribution of attendances per person in each of three years and measured the transition of individual patients between high, low and non-attendance. We fitted data to power law distributions typically seen in complex systems using maximum likelihood estimation.ResultsThe data included 3.6 million attendances at EDs in 13 hospital trusts. 29/39 (74.3%) analyses showed a statistical fit to a power law; 2 (5.1%) fitted an alternative distribution.. All trusts’ data fitted a power law in at least one year. Differences over time and between hospital trusts were small and partly explained by demographics. In contrast, individual patients’ high use was unstable between years.ConclusionsED attendance patterns are stable at the level of the system, but unstable at the level of individual high users. Attendances follow a power law distribution typical of complex systems. Interventions to address ED high use need to consider the whole system and not just the individual high users.

scholarly journals Frequent attendance at the emergency department shows typical features of complex systems: analysis of multicentre linked data

2021 ◽  
pp. emermed-2020-210772
Author(s):  
Christopher Burton ◽  
Tony Stone ◽  
Phillip Oliver ◽  
Jon M Dickson ◽  
Jen Lewis ◽  
...  
Keyword(s):  
Complex Systems ◽  
Power Law ◽  
Likelihood Estimation ◽  
Power Law Distribution ◽  
Health Records ◽  
Frequent Attenders ◽  
Frequent Attendance ◽  
The Individual ◽  
The Uk ◽  
Power Law Distributions

ObjectiveFrequent attendance at the ED is a worldwide problem. We hypothesised that frequent attendance could be understood as a feature of a complex system comprising patients, healthcare and society. Complex systems have characteristic statistical properties, with stable patterns at the level of the system emerging from unstable patterns at the level of individuals who make up the system.MethodsAnalysis of a linked dataset of routinely collected health records from all 13 hospital trusts providing ED care in the Yorkshire and Humber region of the UK (population 5.5 million). We analysed the distribution of attendances per person in each of 3 years and measured the transition of individual patients between frequent, infrequent and non-attendance. We fitted data to power law distributions typically seen in complex systems using maximum likelihood estimation.ResultsThe data included 3.6 million attendances at EDs in 13 hospital trusts. 29/39 (74.3%) analyses showed a statistical fit to a power law; 2 (5.1%) fitted an alternative distribution. All trusts’ data fitted a power law in at least 1 year. Differences over time and between hospital trusts were small and partly explained by demographics. In contrast, individual patients’ frequent attendance was unstable between years.ConclusionsED attendance patterns are stable at the level of the system, but unstable at the level of individual frequent attenders. Attendances follow a power law distribution typical of complex systems. Interventions to address ED frequent attendance need to consider the whole system and not just the individual frequent attenders.

scholarly journals Are Giant Pulses Evidence of Self-Organized Criticality?

1996 ◽  
Vol 160 ◽  
pp. 179-180 ◽  
Author(s):  
Matthew D. T. Young ◽  
Brian G. Kenny
Keyword(s):  
Power Laws ◽  
Crab Pulsar ◽  
Statistical Distributions ◽  
Millisecond Pulsar ◽  
Recent Discussion ◽  
Scale Invariant ◽  
Giant Pulse ◽  
Self Organized ◽  
Giant Pulses ◽  
Self Organized Criticality

The statistical distributions of certain giant pulse (GP) properties appear to be well described by power laws. This suggests that the emission mechanism that produces giant pulses is a scale-invariant one. In turn this may indicate that the source of the GPs is in a state of self-organized criticality (SOC). For a recent discussion of SOC see Sornetteet al. (1995).Prior to this conference, the only pulsars reported to exhibit GPs were the Crab pulsar, PSR B0531+21 (Lundgrenet al. 1995), and the millisecond pulsar PSR B1937+21 (Cognardet al. 1996). However, at the conference it was reported that giantmicropulseshad recently been observed from PSR J0437–4715 (Ables and McConnell, this volume). In all cases the statistical distributions of observed GP heights and/or fluxes are found to be well described by simple power laws. The arguments in this note apply to all these pulsars.

POWER LAW DISTRIBUTION IN EDUCATION: EFFECT OF ECONOMICAL, TEACHING, AND STUDY CONDITIONS IN UNIVERSITY ENTRANCE EXAMINATION

2003 ◽  
Vol 14 (04) ◽  
pp. 449-457 ◽  
Author(s):  
HARI M. GUPTA ◽  
JOSÉ R. CAMPANHA ◽  
FÁBIO R. CHAVARETTE
Keyword(s):  
Biological Sciences ◽  
Power Law ◽  
Family Income ◽  
Mean Value ◽  
Entrance Examination ◽  
Power Law Distribution ◽  
Student’S Performance ◽  
The Mean ◽  
Power Law Distributions ◽  
University Entrance Examination

We studied the statistical distribution of student's performance, which is measured through their marks, in university entrance examination (Vestibular) of UNESP (Universidade Estadual Paulista) with respect to (i) period of study — day versus night period (ii) teaching conditions — private versus public school (iii) economical conditions — high versus low family income. We observed long ubiquitous power law tails in physical and biological sciences in all cases. The mean value increases with better study conditions followed by better teaching and economical conditions. In humanities, the distribution is close to normal distribution with very small tail. This indicates that these power law tails in science subjects are due to the nature of the subjects themselves. Further and better study, teaching and economical conditions are more important for physical and biological sciences in comparison to humanities at this level of study. We explain these statistical distributions through Gradually Truncated Power law distributions. We discuss the possible reason for this peculiar behavior.

scholarly journals Spectral Flattening of Crab Giant Pulses at Low Frequencies

2017 ◽  
Vol 13 (S337) ◽  
pp. 378-379
Author(s):  
Bradley W. Meyers ◽  
Steven E. Tremblay ◽  
N. D. Ramesh Bhat ◽  
Ryan M. Shannon
Keyword(s):  
Crab Pulsar ◽  
Giant Pulse ◽  
Pulse Emission ◽  
Low Frequencies ◽  
Pulsar Radio ◽  
Giant Pulses ◽  
Spectral Behaviour ◽  
The Mean ◽  
Murchison Widefield Array ◽  
Pulsar Radio Emission

AbstractThe frequency dependence of normal pulsar radio emission is typically observed to be a power law, with some indications of a flattening or turnover at low frequencies (≲ 100 MHz). The spectrum of the Crab pulsar’s giant pulse emission has not been examined as closely. We conducted simultaneous wideband observations of the Crab pulsar, with the Parkes radio telescope and the Murchison Widefield Array, to study the spectral behaviour of its giant pulses. Our analysis shows that the mean spectral index of Crab giant pulses flattens at low frequencies, from −2.6 ± 0.5 between the Parkes bands, to −0.7 ± 1.4 between the lowest MWA subbands.

scholarly journals Detection of giant pulses in PSR J1047−6709

2020 ◽  
Author(s):  
S N Sun ◽  
W M Yan ◽  
N Wang
Keyword(s):  
Power Law Distribution ◽  
Pulse Profile ◽  
Weak State ◽  
Giant Pulses ◽  
Peak Flux ◽  
Average Profile ◽  
The Mean ◽  
First Time ◽  
Insight Into ◽  
Bright Emission

Abstract We report the emission variations in PSR J1047−6709 observed at 1369 MHz using the Parkes 64 m radio telescope. This pulsar shows two distinct emission states: a weak state and a bright emission state. We detected giant pulses (GPs) in the bright state for the first time. We found 75 GPs with pulse width ranging from 0.6 to 2.6 ms. The energy of GPs follows a power-law distribution with the index α = −3.26 ± 0.22. The peak flux density of the brightest GP is 19 Jy which is 110 times stronger than the mean pulse profile. The polarization properties of the average profile of GPs are similar to that of the pulses with energy less than 10 times average pulse energy in the bright state. This indicates that the emission mechanism is basically the same for them. Our results provide a new insight into the origin of the GPs in pulsars.

A Simple Method for the Evaluation of Internal Doses in Nuclear Medicine

1974 ◽  
Vol 13 (02) ◽  
pp. 193-206
Author(s):  
L. Conte ◽  
L. Mombelli ◽  
A. Vanoli
Keyword(s):  
Nuclear Medicine ◽  
Close Agreement ◽  
Whole Body ◽  
Simple Method ◽  
Rapid Estimation ◽  
Absorbed Doses ◽  
The Mean ◽  
The Individual ◽  
Estimation Of Risk

SummaryWe have put forward a method to be used in the field of nuclear medicine, for calculating internally absorbed doses in patients. The simplicity and flexibility of this method allow one to make a rapid estimation of risk both to the individual and to the population. In order to calculate the absorbed doses we based our procedure on the concept of the mean absorbed fraction, taking into account anatomical and functional variability which is highly important in the calculation of internal doses in children. With this aim in mind we prepared tables which take into consideration anatomical differences and which permit the calculation of the mean absorbed doses in the whole body, in the organs accumulating radioactivity, in the gonads and in the marrow; all this for those radionuclides most widely used in nuclear medicine. By comparing our results with dose obtained from the use of M.I.R.D.'s method it can be seen that when the errors inherent in these types of calculation are taken into account, the results of both methods are in close agreement.

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

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