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  • 1
    Electronic Resource
    Electronic Resource
    Morphology and modes of cell proliferation in earliest signet-ring-cell carcinomas induced in canine stomachs byN-ethyl-N′-nitro-N- nitrosoguanidine (1991)
    Springer
    Journal of cancer research and clinical oncology 117 (1991), S. 197-204 
    Details
    ISSN: 1432-1335
    Keywords: Stomach ; Signet-ring-cell carcinoma ; Cell kinetics ; Bromodeoxyuridine ; N-ethyl-N′-nitro-N-nitrosoguanidine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Signet-ring-cell carcinomas were induced in the stomach of 12 beagle dogs by p.o. administration ofN-ethyl-N′-nitro-N-nitrosoguanidine (ENNG), and the morphology and modes of cell proliferation in an incipient stage of cancer growth were studied with bromodeoxyuridine (BrdUrd) incorporation. From 5 to 27 months after the completion of 8 months' carcinogen treatment, minute carcinomas were found in the stomachs of 9 dogs. Before sacrifice, the dogs were given a single or repeated i.v. injections of BrdUrd for 1–3 days. Minute signet-ring-cell carcinomas were found to form a layered structure, in which the cancer cells proliferated in the lamina propria at the gland-neck level and differentiated to postmitotic signet-ring cells at the upper and lower levels of the mucosa. From repeated injections of BrdUrd, the time required for all the proliferative cells to be labelled with BrdUrd (reflecting the maximum cellcycle time) was estimated to be 1.7 days for the normal glands, and 2.7 days for minute signet-ring-cell carcinomas. From the labelling index with BrdUrd as well as from the morphology, earliest carcinomas were identified in the single gland. There remained atrophic normal epithelium commonly in the single-gland lesions. Proliferative atypical cells appeared to be shed into the stroma passively through the atrophy and subsequent collapse of the gland rather than through active invasion. This may be a reason why cancer cells in minute signet-ring cell carcinomas preserved the normal pattern of cell renewal movement to form the layered structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01625425
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Theory of superconductivity. 3. 2D conduction bands for high Tc. Bose-Einstein condensation transition of the third order (1992)
    Springer
    Journal of superconductivity 5 (1992), S. 219-237 
    Details
    ISSN: 1572-9605
    Keywords: Theory of superconductivity ; new formula forT c ; high-T c superconductor ; Bose-Einstein condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract A general theory of superconductivity is developed, starting with a BCS Hamiltonian in which the interaction strengths (V 11,V 22,V 12) among and between “electron” (1) and “hole” (2) Cooper pairs are differentiated, and identifying “electrons” (“holes”) with positive (negative) masses as those Bloch electrons moving on the empty (filled) side of the Fermi surface. The supercondensate is shown to be composed of equal numbers of “electron” and “hole” ground (zero-momentum) Cooper pairs with charges ±2e and different masses. This picture of a neutral supercondensate naturally explains the London rigidity and the meta-stability of the supercurrent ring. It is proposed that for a compound conductor the supercondensate is formed between “electron” and “hole” Fermi energy sheets with the aid of optical phonons having momenta greater than the minimum distance (momentum) between the two sheets. The proposed model can account for the relatively short coherence lengthsξ observed for the compound superconductors including intermetallic compound, organic, and cuprous superconductors. In particular, the model can explain why these compounds are type II superconductors in contrast with type I elemental superconductors whose condensate is mediated by acoustic phonons. A cuprous superconductor has 2D conduction bands due to its layered perovskite lattice structure. Excited (nonzero momentum) Cooper pairs (bound by the exchange of optical phonons) aboveT c are shown to move like free bosons with the energy-momentum relationɛ=1/2vFq. They undergo a Bose-Einstein condensation atT c = 0.977ħv F k b −1 n 1/2, wheren is the number density of the Cooper pairs. The relatively high value ofT c (∼100 K) arises from the fact that the densityn is high:n 1/2∼ξ−1 ∼107 cm−1. The phase transition is of the third order, and the heat capacity has a reversed lambda (λ)-like peak atT c .
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617622
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  • 3
    Electronic Resource
    Electronic Resource
    On the Bose-Einstein condensation of nonzero-momentum cooper pairs. A second-order phase transition (1991)
    Springer
    Journal of superconductivity 4 (1991), S. 297-310 
    Details
    ISSN: 1572-9605
    Keywords: Theory of superconductivity ; new formula forT c ; BE condensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Based on the BCS Hamiltonian, the normal-to-super phase transition is investigated, approaching the critical temperatureT c from the high-temperature side. Nonzero-momentum Cooper pairs, that is, pairs of electrons (holes) with antiparallel spins and nearly opposite momenta aboveT c in the bulk limit, are shown to move like independent bosons with the energyε vs. momentump relationε=1/2vF ν, whereν F represents the Fermi velocity (1/2m*ν F 2 ≡ε F≡Fermi energy). The system of free Cooper pairs undergoes a phase transition of the second order with the critical temperatureT c given byk B T c=1/2(π2ħ3 ν F 3 n/1.20257)1/3 wheren is the number density of Cooper pairs. The ratio of the jump of the heat capacity, ΔC, to the maximum heat capacity,C s, is a universal constant: ΔC/C s=0.60874; this number is close to the universal constant 0.588 obtained by the finite-temperature BCS theory. The physical significance of these results is discussed, referring to the well-known BCS theory, which treats the many-Cooper-pair ground state exactly and the thermodynamic state belowT c approximately. An explanation is proposed on the question why sodium should remain normal down to 0 K, based on the band structures with the hypothesis that the supercondensate composed of zero-momentum “electron” and “hole” Cooper pairs is electrically neutral.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618152
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    Paper (German National Licenses)
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