2,681 research outputs found
The space and technology transfer program Quarterly report, Jun. - Aug. 1970
Space and technology transfer program of KAS
The space and technology transfer program Annual report
Space and technology transfer program at Knowledge Availability Center of Pittsburgh Universit
Young's experiment and the finiteness of information
Young's experiment is the quintessential quantum experiment. It is argued
here that quantum interference is a consequence of the finiteness of
information. The observer has the choice whether that information manifests
itself as path information or in the interference pattern or in both partially
to the extent defined by the finiteness of information.Comment: 5 pages, 3 figures, typos remove
Oligocene Deep Water Export from the North Atlantic and the Development of the Antarctic Circumpolar Current Examined with Neodymium Isotopes
Neodymium (Nd) isotopes were measured on 181 samples of fossil fish teeth recovered from Oligocene toMiocene sections at Ocean Drilling Program Site 1090 (3700 m water depth) on Agulhas Ridge in the Atlanticsector of the Southern Ocean. A long-term decreasing trend toward less radiogenic Nd isotope compositionsdominates the record. This trend is interrupted by shifts toward more radiogenic compositions near the early/lateOligocene boundary and the Oligocene/Miocene boundary. Overall, eNd values at Agulhas Ridge are moreradiogenic than at other Atlantic locations, and are similar to those at Indian Ocean locations. The pattern ofvariability is remarkably similar to Nd isotope results from Walvis Ridge (South Atlantic) and Ninetyeast Ridge(Indian Ocean). In contrast, Agulhas Ridge and Maud Rise Nd isotope records do not show similar patterns overthis interval. Results from this study indicate that deep water in the Atlantic flowed predominantly from north tosouth during the Oligocene and Miocene, and that export of Northern Component Water (NCW) to the SouthernOcean increased in the late Oligocene. There is also evidence for efficient exchange of deep waters between theAtlantic sector of the Southern Ocean and the Indian Ocean, although the direction of deep water flow is notentirely clear from these data. The shifts to more radiogenic Nd isotopic compositions most likely representincreases in the flux of Pacific waters through Drake Passage, and the timing of these events reflect developmentof a mature Antarctic Circumpolar Current (ACC). The relative timing of increased NCW export and ACCmaturation support hypotheses that link deep water formation in the North Atlantic to the opening of DrakePassage
Relative hyperbolicity and similar properties of one-generator one-relator relative presentations with powered unimodular relator
A group obtained from a nontrivial group by adding one generator and one
relator which is a proper power of a word in which the exponent-sum of the
additional generator is one contains the free square of the initial group and
almost always (with one obvious exception) contains a non-abelian free
subgroup. If the initial group is involution-free or the relator is at least
third power, then the obtained group is SQ-universal and relatively hyperbolic
with respect to the initial group.Comment: 11 pages. A Russian version of this paper is at
http://mech.math.msu.su/department/algebra/staff/klyachko/papers.htm V3:
revised following referee's comment
Induction of tolerance to a murine fibrosarcoma in two zones of dosage--the involvement of suppressor cells.
Small size inocula (10(1)-10(3) cells) of cells from a syngeneic methylcholanthrene-induced fibrosarcoma (FSA) induced tolerance when injected s.c. into C3Hf mice. Mice were unable to respond to subsequent challenge with moderate, immunogenic doses of FSA. Tolerance was demonstrated in an in vivo transfer (Winn) assay and an in vitro tumour-specific TH cell assay. Low zone tolerance was associated with the presence of tumour-specific TS cells in the spleen. Moderate size inocula (10(4)-10(6) FSA cells) were immunogenic but larger cell doses (greater than 10(6)) were again tolerogenic. In the high zone, tolerance was associated with both tumour-specific TS cells and non T suppressor cells that were not tumour-specific. These results support the view that immunogenic tumours, as they grow from small cell numbers, might be able to escape host surveillance by specifically tolerizing the immune system. They also suggest that large tumour burdens can interfere with the host's immune response by inducing suppressor cells
L^2-Betti numbers of one-relator groups
We determine the L^2-Betti numbers of all one-relator groups and all
surface-plus-one-relation groups (surface-plus-one-relation groups were
introduced by Hempel who called them one-relator surface groups). In particular
we show that for all such groups G, the L^2-Betti numbers b_n^{(2)}(G) are 0
for all n>1. We also obtain some information about the L^2-cohomology of
left-orderable groups, and deduce the non-L^2 result that, in any
left-orderable group of homological dimension one, all two-generator subgroups
are free.Comment: 18 pages, version 3, minor changes. To appear in Math. An
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