Generalized semistable probability distributions in Hilbert space

1980 ◽  
Vol 20 (2) ◽  
pp. 111-118 ◽  
Author(s):  
D. Krapavickaitė
1980 ◽  
Vol 22 (3) ◽  
pp. 479-480
Author(s):  
R.G. Laha ◽  
V.K. Rohatgi

A faulty typescript of [2] was, regrettably, submitted. The following changes should be made:Page 398, line 7: replace A є G with A є L.Page 398, line 12: replace A є G with A є L.


1980 ◽  
Vol 22 (3) ◽  
pp. 397-406 ◽  
Author(s):  
R.G. Laha ◽  
V.K. Rohatgi

A characterization of the class of operator semistable probability measures on a real separable Hilbert space is given.


2020 ◽  
Vol 75 (5) ◽  
pp. 465-473 ◽  
Author(s):  
Jürgen Schnack ◽  
Johannes Richter ◽  
Tjark Heitmann ◽  
Jonas Richter ◽  
Robin Steinigeweg

AbstractAccording to the concept of typicality, an ensemble average can be accurately approximated by an expectation value with respect to a single pure state drawn at random from a high-dimensional Hilbert space. This random-vector approximation, or trace estimator, provides a powerful approach to, e.g. thermodynamic quantities for systems with large Hilbert-space sizes, which usually cannot be treated exactly, analytically or numerically. Here, we discuss the finite-size scaling of the accuracy of such trace estimators from two perspectives. First, we study the full probability distribution of random-vector expectation values and, second, the full temperature dependence of the standard deviation. With the help of numerical examples, we find pronounced Gaussian probability distributions and the expected decrease of the standard deviation with system size, at least above certain system-specific temperatures. Below and in particular for temperatures smaller than the excitation gap, simple rules are not available.


1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.


Author(s):  
J. R. Retherford
Keyword(s):  

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