Does the death postponement phenomenon really exist?

It is a common belief that people close to death from natural causes can postpone their imminent death if they see a strong reason to survive a bit longer. This is known as the Postponement hypothesis: that a meaningful occasion can act as a motivator to prolong life for a short amount of time. A few studies have already addressed this hypothesis but their conclusions are contradictory.To check the postponement hypothesis, we analysed almost 249 thousand cases in the dataset for South African people who died in the year 2015. We took a person’s birthday as the meaningful occasion and analyse the death rate around this date using statistical models offered by survival analysis. If the hypothesis is true, it can be expected that the mortality rate should be lower a period just before the birthday and, perhaps, higher shortly afterwards.The results of our analysis show that no postponement of death can be seen for the examined dataset. In fact, to the contrary, the data suggest that the mortality rate is higher both before and after the birthday. Speculations as to why this is the case might be a higher risk associated with the stress of expectations for the birthday as well as an earlier start of celebrations with associated departure from the recommended regime

Amendment to: populations in environments with a soft carrying capacity are eventually extinct

This sharpens the result in the paperJagers and Zuyev (J Math Biol 81:845-851, 2020): consider a population changing at discrete (but arbitrary and possibly random) time points, the conditional expected change, given the complete past population history being negative, whenever population size exceeds a carrying capacity. Further assume that there is an epsilon > 0 such that the conditional probability of a population decrease at the next step, given the past, always exceeds epsilon if the population is not extinct but smaller than the carrying capacity. Then the population must die out

Functional Central Limit Theorems for Occupancies and Missing Mass Process in Infinite Urn Models

We study the infinite urn scheme when the balls are sequentially distributed over an infinite number of urns labeled 1,2,..\ua0so that the urn j at every draw gets a ball with probability pj, where ∑ jpj= 1. We prove functional central limit theorems for discrete time and the Poissonized version for the urn occupancies process, for the odd occupancy and for the missing mass processes extending the known non-functional central limit theorems

Properties of Silicon Dioxide Amorphous Nanopowder Produced by Pulsed Electron Beam Evaporation

SiO2 amorphous nanopowder (NP) is produced with the specific surface area of 154 m2/g by means of evaporation by a pulsed electron beam aimed at Aerosil 90 pyrogenic amorphous NP (90 m2/g) as a target. SiO2 NP nanoparticles showed improved magnetic, thermal, and optical properties in comparison to Aerosil 90 NP. Possible reasons of emergence of d0 ferromagnetism at the room temperature in SiO2 amorphous NP are discussed. Photoluminescent and cathode luminescent properties of the SiO2 NP were investigated

Impact of Road Vehicle Accelerations on SAR-GMTI Motion Parameter Estimation

In recent years many powerful techniques and algorithms have been developed to detect moving targets and estimate their motion parameters from single- or multi-channel SAR data. In case of single- and two-channel systems, most of the developed algorithms rely on analysis of the Doppler history. Nowadays it is known, that even small unconsidered across-track accelerations can bias the along-track velocity estimation. Since we want to monitor real and more complex traffic scenarios with a future traffic monitoring system like TRAMRAD, we must know which target accelerations we have to handle in reality. For this reason a common passenger car was equipped with an inertial measurement system and differential GPS to measure accelerations in all three dimensions during rush-hour traffic. In this paper the results of the acceleration measurements are presented and discussed. The standard deviations of the measured accelerations are in the order of 0.5 m/s2 for accelerations in driving direction and 0.6 m/s2 for radial accelerations. A theoretical analysis (which is verified by detailed simulations) of the Doppler slope shows also that at such high across-track accelerations a reliable estimation of the along-track velocity by means of a Doppler slope analysis without further information is unemployable in practice. Also oscillations of the car body along the vertical axis are investigated in this paper. From the field of vehicle dynamics it is known that the eigen frequencies of the car body are in the range from 0.7 to 2.0 Hz. Deflections in the order of one wavelength (X-band) or higher are possible at such frequencies. The simulation results for spaceborne SAR systems with integration times in the order of one second show that the shape and azimuth shift of the impulse response depend beside the oscillation frequency and the deflection also on the initial phase of the oscillation. However, at practical applications the main part of the energy could also be reflected by double bounce from the road surface. Thus, further investigations in the topic of vehicle oscillations by using real radar data are necessary. Finally, some basic ideas are presented which enable a reliable separation between along-track velocity and across-track acceleration. For example, the easiest way to separate both just mentioned motion parameters is the use of a road database, from which the information about the motion direction of the assigned vehicle can be extracted. Hence, the accuracy of along-track velocity estimation is mainly given by the accuracy of the estimated across-track velocity and the angle of the road section in relation to the flight path of the SAR platform