scholarly journals Scaling laws and phase space analysis of a geomagnetic domino model

2021 ◽  
Vol 2090 (1) ◽  
pp. 012030
Author(s):  
K Peqini ◽  
D Prenga ◽  
R Osmanaj
Keyword(s):  
Phase Space ◽  
Scaling Laws ◽  
Outer Core ◽  
Main Field ◽  
Field Reversal ◽  
Core Dynamics ◽  
The Mean ◽  
Reversed Polarity ◽  
The Relationship ◽  
Mean Time

Abstract The geomagnetic field is among the most striking features of the Earth. By far the most important ingredient of it is generate in the fluid conductive outer core and it is known as the main field. It is characterized by a strong dipolar component as measured on the Earth’s surface. It is well established the fact that the dipolar component has reversed polarity many times, a phenomenon dubbed as dipolar field reversal (DFR). There have been proposed numerous models focused on describing the statistical features of the occurrence of such phenomena. One of them is the domino model, a simple toy model that despite its simplicity displays a very rich dynamic. This model incorporates several aspects of the outer core dynamics like the effect of rotation of Earth, the appearance of convective columns which create their own magnetic field, etc. In this paper we analyse the phase space of parameters of the model and identify several regimes. The two main regimes are the polarity changing one and the regime where the polarity remains the same. Also, we draw some scaling laws that characterize the relationship between the parameters and the mean time between reversals (mtr), the main output of the model.

RELIABILITY PROPERTIES OF MEAN TIME TO FAILURE IN AGE REPLACEMENT MODELS

2010 ◽  
Vol 17 (01) ◽  
pp. 15-26 ◽  
Author(s):  
G. ASHA ◽  
N. UNNIKRISHNAN NAIR
Keyword(s):  
Residual Life ◽  
Stochastic Orders ◽  
Mean Residual Life ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Replacement Model ◽  
The Mean ◽  
Age Replacement ◽  
The Relationship ◽  
Mean Time

In this article some properties of the mean time to failure in an age replacement model is presented by examining the relationship it has with hazard (reversed hazard) rate and mean (reversed mean) residual life functions. An ordering based on mean time to failure is used to examine its implications with other stochastic orders.

scholarly journals Efficacy and adverse events related to the initial dose of methimazole in children and adolescents with Graves’ disease

2021 ◽  
Vol 26 (3) ◽  
pp. 199-204
Author(s):  
Hyun Gyung Lee ◽  
Eun Mi Yang ◽  
Chan Jong Kim
Keyword(s):  
Adverse Events ◽  
Children And Adolescents ◽  
Liver Dysfunction ◽  
Initial Dose ◽  
Graves Disease ◽  
Group A ◽  
The Mean ◽  
Group B ◽  
The Relationship ◽  
Mean Time

Purpose: The first-line antithyroid drug for children and adolescents with Graves’ disease (GD) is methimazole (MMI). This study evaluated the relationship between the initial MMI dose and the clinical course of GD after treatment.Methods: We studied the efficacy of the initial MMI dose and the relationship between the initial MMI dose and adverse events (AEs). We retrospectively enrolled 22 males and 77 females and divided those subjects into 3 groups according to the initial dose of MMI: <0.4 mg/kg/day (group A; n=32); 0.4–0.7 mg/kg/day (group B; n=39); and >0.7 mg/kg/day (group C; n=28).Results: The mean time to the normalization of free thyroxine (fT4) levels upon initial treatment was 5.64, 8.61, and 7.98 weeks in groups A, B, and C, respectively (P=0.116). The incidence of liver dysfunction, neutropenia, and skin rash was 12.5%, 20.5%, and 42.9% in groups A, B, and C, respectively (P=0.018). Neutropenia, as a severe AE, was absent in group A, but its prevalence was 7.7% in group B and 21.4% in group C (P=0.015). When comparing only groups B and C, the incidences of liver dysfunction and neutropenia were higher in group C (P=0.04 and P=0.021, respectively).Conclusion: The mean time to the normalization of fT4 levels did not differ among the 3 groups, but the incidence of AEs was higher in the groups that received high MMI doses. High doses of MMI (>0.7 mg/kg/day) should be reconsidered as an initial treatment for children and adolescents with GD.

Melnikov Process for Stochastically Perturbed, Slowly Varying Oscillators: Application to a Model of Wind-Driven Coastal Currents

1996 ◽  
Vol 63 (2) ◽  
pp. 429-435 ◽  
Author(s):  
E. Simiu
Keyword(s):  
Phase Space ◽  
Necessary Conditions ◽  
System Modeling ◽  
Time Interval ◽  
Stochastic Perturbations ◽  
The Mean ◽  
Induced Currents ◽  
Chaotic Transport ◽  
Parameter Ranges ◽  
Mean Time

The stochastic Melnikov approach is extended to a class of slowly varying dynamical systems. It is found that (1) necessary conditions for chaos induced by stochastic perturbations depend on the excitation spectrum and the transfer function in the expression for the Melnikov transform; (2) the Melnikov approach allows the estimation of lower bounds for (a) the mean time of exit from preferred regions of phase space, and (b) the probability that exits from those regions cannot occur during a specified time interval. For a system modeling wind-induced currents, the deterministic Melnikov approach would indicate that chaotic transport cannot occur for certain parameter ranges. However, the more realistic stochastic Melnikov approach shows that, for those same parameter ranges, the necessary conditions for exits during a specified time interval are satisfied with probabilities that increase as the time interval increases.

scholarly journals Are there correlations between attention, physical endurance and anthropometric parameters of athletes?

2019 ◽  
Vol 11 (1) ◽  
pp. 103-109
Author(s):  
Mirosław Mikicin ◽  
Sylwia Nowacka-Dobosz ◽  
Anna Mróz ◽  
Anna Kuk ◽  
Adriana Zagórska-Pachucka
Keyword(s):  
Performance Test ◽  
Visual Orientation ◽  
Physical Endurance ◽  
Test Results ◽  
Endurance Running ◽  
Anthropometric Parameters ◽  
The Mean ◽  
Vienna System ◽  
The Relationship ◽  
Mean Time

SummaryStudy aim: The aim of the study was to investigate the relationship between attention and physical endurance (running) and anthropometric parameters of athletes.Material and methods: The study examined 61 students aged 19 to 25 years, divided into two groups: athletes (33 participants) and non-athletes (28 participants). We employed anthropometric measurements and the Vienna System Test, including tools to measure focused attention, such as LVT (visual orientation performance test) and DAUF (test for examination of sustained attention) and the Cooper test to measure endurance.Results: Analysis of the results demonstrated a relationship between attention and physical endurance with median time from LVT (r = –0.552). A relationship was also found between the Cooper test results and the mean time to incorrect answer (r = –0.900).Conclusions: The analysis demonstrated a relationship between attention, physical endurance and anthropometric parameters of athletes.

Structure and Luminescence Characteristics of Terbium Hydroxide Nanosheets Doped with Eu3+

2012 ◽  
Vol 512-515 ◽  
pp. 174-177 ◽  
Author(s):  
Lin Zhang ◽  
Cai Xia Li ◽  
Dan Yu Jiang ◽  
Lei Su ◽  
Qiang Li
Keyword(s):  
Hydrothermal Reaction ◽  
Ultrasonic Method ◽  
Preparation Time ◽  
Layer Compound ◽  
Ion Exchange Reaction ◽  
The Mean ◽  
The Relationship ◽  
Mean Time ◽  
Luminescence Characteristics ◽  
Xrd And Tem

Eu3+ doped terbium hydroxide nanosheets were successfully synthesized from layer compound of Tb2(OH)5NO3·1.5H2O doped by Eu3+. Firstly layer compound of Tb2(OH)5NO3·1.5H2O doped by Eu3+ was obtained by hydrothermal reaction at 1200 . After ion exchange reaction with SDS under the microwave condition, the layer space of the compound increases from 0.907 nm to 2.34 nm. Furthermore stable nanosheet sol was obtained after exfoliation under ultrasonic condition. At the mean time we discovered that microwave and ultrasonic method can greatly shorten the preparation time. The structure of layer compound and the morphology of nanosheets were determined by XRD and TEM. The luminescence properties of terbium hydroxide nanosheets doped with Eu3+ were examined; the relationship between structure and spectra was discussed

Microelectrode recording-determined subthalamic nucleus length not predictive of stimulation-induced side effects

2005 ◽  
Vol 19 (5) ◽  
pp. 1-5 ◽  
Author(s):  
Shearwood McClelland ◽  
Brian Kim ◽  
Linda M. Winfield ◽  
Blair Ford ◽  
Tresha A. Edwards ◽  
...  
Keyword(s):  
Side Effects ◽  
Subthalamic Nucleus ◽  
Systematic Difference ◽  
Common Side Effect ◽  
Microelectrode Recording ◽  
Electrode Implantation ◽  
Significant Difference ◽  
The Mean ◽  
The Relationship ◽  
Mean Time

Object Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has become a popular treatment for patients with medically refractory Parkinson disease. Many surgeons believe that microelectrode recording (MER) during DBS electrode implantation is needed to optimize placement, whereas stimulation-induced side effects such as paresthesias, dystonic contractions, dyskinesias, and ocular motor signs that become apparent postoperatively may be an indicator of the proximity of the electrode to various boundaries of the STN. This study was performed to evaluate the relationship between mapping of the STN by using MER and postoperative stimulation-induced side effects. Methods Eighty-two electrodes implanted in 75 patients between March 1999 and March 2003 were retrospectively examined to evaluate the length of the STN defined by MER, and the number of and threshold for postoperative stimulation-induced side effects. Electrodes were typically tested with increasing stimulation amplitudes (maximum 6 V) by using a monopolar array. The 82 electrodes were associated with 97 stimulation-induced side effects. The mean time between surgery and testing stimulation-induced side effects was 3.9 months. Statistical analysis (two-tailed t-test) revealed no significant difference in the number of stimulation-induced side effects (or the mean threshold for paresthesias, the most common side effect) for electrodes associated with an STN length less than 4.5 mm (13 electrodes) compared with those associated with an STN greater than or equal to 4.5 mm (69 electrodes, p = 0.616). For every electrode, the target adjustment based on MER results was within 2 mm of the image-planned target (usually 1 mm anterior). In the x axis (medial–lateral orientation), there was no systematic difference in adjustments made for the electrodes associated with the shorter compared with the longer STN lengths. In the y axis (anterior–posterior orientation), there was a very small statistically significant difference in the mean adjustment (0.4 mm) between the two groups. Conclusions Analysis of these results suggests that a shorter MER-determined STN length alone does not reliably predict the incidence of stimulation-induced side effects.

Viscosity and density dependence during maximal flow in man

1980 ◽  
Vol 48 (2) ◽  
pp. 313-319 ◽  
Author(s):  
B. A. Staats ◽  
T. A. Wilson ◽  
S. J. Lai-Fook ◽  
J. R. Rodarte ◽  
R. E. Hyatt
Keyword(s):  
Density Dependence ◽  
Scaling Laws ◽  
Peripheral Resistance ◽  
Maximal Flow ◽  
Flow Curves ◽  
Gas Density ◽  
Maximal Expiratory Flow ◽  
The Mean ◽  
The Relationship ◽  
Viscosity Dependence

Maximal expiratory flow curves were obtained from ten healthy subjects white breathing air and three other gas mixtures with different densities and viscosities. From these data, the magnitudes of the dependence of maximal flow on gas density and viscosity were obtained. The scaling laws of fluid mechanics, together with a model for the flow-limiting mechanism, were used to obtain a prediction of the relationship between the density dependence and the viscosity dependence of maximal flow. Although the data for individual subjects were too variable to allow a precise comparison with this prediction, the relationship between the mean density dependence and the mean viscosity dependence of all usbjects agreed with the theoretic prediction. This agreement supports the assumption, which is frequently made, that flow resistance rather than tissue visoelasticity is the dominant contributor to peripheral resistance. Information on the relationships between the pressure drop to the flow-limiting segment and flow, gas density and viscosity, and lung volume were also obtained.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

Predicting Daily Maintenance Dose of Fluindione, an Oral Anticoagulant Drug

1996 ◽  
Vol 75 (05) ◽  
pp. 731-733 ◽  
Author(s):  
V Cazaux ◽  
B Gauthier ◽  
A Elias ◽  
D Lefebvre ◽  
J Tredez ◽  
...  
Keyword(s):  
Effective Dose ◽  
Maintenance Dose ◽  
Successive Approximations ◽  
Hemorrhagic Complication ◽  
Simple Method ◽  
Individual Variations ◽  
Anticoagulant Drug ◽  
The Mean ◽  
Mean Time ◽  
Daily Maintenance Dose

SummaryDue to large inter-individual variations, the dose of vitamin K antagonist required to target the desired hypocoagulability is hardly predictible for a given patient, and the time needed to reach therapeutic equilibrium may be excessively long. This work reports on a simple method for predicting the daily maintenance dose of fluindione after the third intake. In a first step, 37 patients were delivered 20 mg of fluindione once a day, at 6 p.m. for 3 consecutive days. On the morning of the 4th day an INR was performed. During the following days the dose was adjusted to target an INR between 2 and 3. There was a good correlation (r = 0.83, p<0.001) between the INR performed on the morning of day 4 and the daily maintenance dose determined later by successive approximations. This allowed us to write a decisional algorithm to predict the effective maintenance dose of fluindione from the INR performed on day 4. The usefulness and the safety of this approach was tested in a second prospective study on 46 patients receiving fluindione according to the same initial scheme. The predicted dose was compared to the effective dose soon after having reached the equilibrium, then 30 and 90 days after. To within 5 mg (one quarter of a tablet), the predicted dose was the effective dose in 98%, 86% and 81% of the patients at the 3 times respectively. The mean time needed to reach the therapeutic equilibrium was reduced from 13 days in the first study to 6 days in the second study. No hemorrhagic complication occurred. Thus the strategy formerly developed to predict the daily maintenance dose of warfarin from the prothrombin time ratio or the thrombotest performed 3 days after starting the treatment may also be applied to fluindione and the INR measurement.

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