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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)
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)
To B. L. van der Waerden on his eightieth birthday 1. For every set X and every cardinal number r we put if and only if x k = ^ for XeL. In [1] the following result was proved: THEOREM 1. Given any partition f: [A] r-> F, there is an infinite set B ^ A and a set L £ {0, ..., r— 1} such that fis L-canonical on B. The object of this note is (i) to give a new(More)
Let S be an abstract set and n, an ordinal number. Denote by 1V,S(n) the set of all vectors over S of " length " n, i.e. the set of all mappings v->x, of [0, n) into S. As notation for such a vector we use juxtaposition of its components : X = xo xl. .. (m < n) Ws(n?). Suppose that x < y is a quasi-order ([I], p. 4) on S. This order induces ([2]) a(More)