35,097 research outputs found
Delayed particles in EAS at Akeno
Using two 2.25 square meter fast scintillation detectors, delayed particles in cosmic ray showers (CRS) have been observed at Akeno Observatory. These are set under 1 m concrete and 2.5 cm lead plates respectively. About 2500 CRS are analyzed. The lateral distribution of delayed particles for the CRS size 10 to the 7th power is flatter than that for to the 7th power. The lateral density of delayed particles is almost constant for the size range 2.2 X 10 to the 5th power approx. 10 to the 7th power and increases rapidly above 10 to the 7th power. These facts may suggest change of nuclear interaction at 10 to the 7th power and substantially the existence of heavy particles with long life
Intestinal Metaplasia —The Effect of Acid on the Gastric Mucosa and Gastric Carcinogenesis—
This review concerns stem cells and their relation to intestinal metaplasia. When
gastric regions of mice, Mongolian gerbils or several strains of rats were
irradiated with a total dose of 20 Gy of X-rays given in two fractions,
intestinal metaplasia was only induced in rats. In addition, it was greatly
influenced by rat strain and sex. Alkaline phosphatase (ALP) positive
metaplastic foci were increased by administration of ranitidine (H2
receptor antagonist), crude stomach antigens or subtotal resection of the fundus
and decreased by cysteamine (gastric acid secretion stimulator), histamine or
removal of the submandibular glands. Recent studies have shown that
Cdx2 transgenic mice with gastric achlorhydria develop
intestinal metaplasia and that in men and animals, Helicobacter
pylori (H. pyrlori) infection can cause intestinal metaplasias
that are reversible on eradication. Our results combined with findings for
H. pylori infection or eradication and transgenic mice
suggest that an elevation in the pH of the gastric juice due to disappearance of
parietal cells is one of the principal factors for development of reversible
intestinal metaplasia. When different organs were transplanted into the stomach
or duodenum, they were found to transdifferentiate into gastric or duodenal
mucosae, respectively. Organ-specific stem cells in normal non-liver tissues
(heart, kidney, brain and skin) also differentiate into hepatocytes when
transplanted into an injured liver. Therefore, stem cells have a multipotential
ability, transdifferentiating into different organs when transplanted into
different environments. Finally, intestinal metaplasia has been found to
possibly increase sensitivity to the induction of tumors by colon carcinogens of
the 1,2-dimethylhydrazine (DMH), azoxymethane (AOM) or
2-amino-1-methyl-6-phenylimidazo[4.5-b]pyridine (PhIP) type. This carcinogenic
process, however, may be relatively minor compared with the main gastric
carcinogenesis process induced by N-methy1-N’-nitro-N-nitrosoguanidine (MMNG) or
N-methylnitrosourea (MNU), which is not affected by the presence of intestinal
metaplasia. The protocol used in these experiments may provide a new approach to
help distinguish between developmental events associated with intestinal
metaplasia and gastric tumors
Quantum multiparty key distribution protocol without use of entanglement
We propose a quantum key distribution (QKD) protocol that enables three
parties agree at once on a shared common random bit string in presence of an
eavesdropper without use of entanglement. We prove its unconditional security
and analyze the key rate.Comment: 8 pages, no figur
Gap Symmetry of Superconductivity in UPd2Al3
The angle dependent thermal conductivity of the heavy-fermion superconductor
UPdAl in the vortex state was recently measured by Watanabe et al. Here
we analyze this data from two perspectives: universal heat conduction and the
angle-dependence. We conclude that the superconducting gap function
in UPdAl has horizontal nodes and is given by
, with .Comment: 8 pages, 4 figures, improved figures in replacemen
Noise Tolerance of the BB84 Protocol with Random Privacy Amplification
We prove that BB84 protocol with random privacy amplification is secure with
a higher key rate than Mayers' estimate with the same error rate. Consequently,
the tolerable error rate of this protocol is increased from 7.5 % to 11 %. We
also extend this method to the case of estimating error rates separately in
each basis, which enables us to securely share a longer key.Comment: 26 pages, 1 figure, version 2 fills a logical gap in the proof.
Version 3 includes an upper bound on the mutual information with finete code
length by using the decoding error probability of the code. Version 4 adds a
paragraph clarifying that no previous paper has proved that the BB84 with
random privacy amplification can tolerate the 11% error rat
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