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1. INTRODUCTION In this paper our main object is the study of relations between cardinal numbers which are written in the form a-(b o , b,,. . .) r or a-(b)C ~° or (b) (b o b,) Such relations were introduced in [3] and [1]. They are called I-relations, Ii-relations and III-relations respectively, and they will be defined in 3. 1, 3. 2 and 3. 3. In sections(More)
Many new neurons are added to the adult avian brain. Most of them die 3-5 weeks after they are born (Nature (Lond.) 335 (1988) 353; J. Comp. Neurol 411 (1999) 487). Those that survive replace, numerically, older ones that have died (Neuron 25 (2000) 481). It has been suggested that the new neurons enhance the brain's ability to acquire new long-term(More)
1. Introduction. Dedekind's pigeonhole principle, also known as the box argument or the chest of drawers argument (Schubfach-prinzip) can be described, rather vaguely, as follows. If sufficiently many objects are distributed over not too many classes, then at least one class contains many of these objects. In 1930 F. P. Ramsey [12] discovered a remarkable(More)
1. Let S be an ordered set, of power 1 SI and order type 8 = 4, We denote by #* the converse of 4, i.e. the order type obtained from + by replacing every order relation x < y by the corresponding relation y < x, and by wrc the least ordinal number of power N,. It is easy to see that, if ISl=tQ, then S contains a subset S' such that either s' = w,, or 8' =(More)
The mole rat Spalax ehrenbergi is a fossorial rodent. Although its peripheral visual system--eye and optic nerve--is highly degenerated, it shows some sensitivity to light. However, in the usual sense, it is essentially blind. An auditory take-over of the visual lateral geniculate nucleus and at least part of the visual cortices was recently demonstrated.(More)
The anatomy of the middle ear of the blind mole rat, a subterranean rodent that uses seismic signals for long distance communication, is described qualitatively and quantitatively. The ossicular chain is of the parallel type with a lever arms ratio of 0.55 and an effective areal ratio of stapedial footplate to eardrum of 0.09. Assuming an ideal mechanical(More)
Based on morphological and behavioral findings we suggest that the seismic vibratory signals that blind mole-rats (Spalax ehrenbergi) use for intraspecific communication are picked up from the substrate by bone conduction and processed by the auditory system. An alternative hypothesis, raised by others, suggest that these signals are processed by the(More)
I first became aware of Richard Rado's existence in 1933 when his important paper Studien zur Kombinatorik appeared. I thought a great deal about the many fascinating and deep unsolved problems stated in this paper but I never succeeded to obtain any significant results here and since I have to report here about our joint work I will mostly ignore these(More)