Comments on the measurements of multiple muon phenomena

The extensive air showers in the energy around 10 to the 15th power eV include those initiated by astrophysical primary gamma-rays. The observations need a precise measurement on the directions of primary particles. It is one of the methods to measure the directions of high-energy muons in air showers. The accuracy in measuring the direction, by calculating the cosmic-ray phenomena in the atmosphere at very high energy was investgated. The results calculated by Monte Carlo method suggest that one may determine the direction of primary cosmic-rays within errors of 10/3 rad in observing muons of above 100 GeV at sea level

Development of colon cancer after liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis

Between February 26, 1981, and July 30, 1987, 36 patients underwent orthotopic liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis. Three of the 36 recipients died within 3 mo because of graft nonfunction or surgical complications. The other 33 (92%) lived for at least 1 yr. Two of the 33 died after 12 and 14 mo, respectively, of recurrent cholangiocarcinoma that was not diagnosed before transplantation. Four other patients died of recurrent liver failure (three cases) or immunoblastic sarcoma (one case) after 14, 21, 36 and 44 mo. Twenty‐seven (75%) of the patients are still alive 23 to 81 mo after transplantation. Two patients have been diagnosed as having colorectal cancer 11 and 21 mo respectively, after transplantation, for an overall incidence of 5.6% (2 of 36) and a corrected incidence of 6.5% (2 of 31) if the three early deaths and two later deaths caused by cholangiocarcinomas are excluded. It is not known whether colorectal malignancies were present but undetected at the time of transplantation or whether they developed afterward. It is clear that patients who undergo liver transplantation for primary sclerosing cholangitis associated with ulcerative colitis should have careful follow‐up of the colon, including colonoscopy and multiple biopsies of the colorectal mucosa. Whether proctocolectomy should be considered prophylactically after liver transplantation is an unresolved issue.(HEPATOLOGY 1990;11:477–480.) Copyright © 1990 American Association for the Study of Liver Disease

Search for magnetic monopoles using proportional counters filled with helium gas

Slow magnetic monopoles in cosmic rays have been searched at sea level with the detector which consists of seven layers of proportional counters filled with a mixture of He + 20% CH4. The velocities and the energy losses of the incident particles are measured. The upper limit of flux for the monopoles in the velocity range of 1 x 0.001 Beta 4 x 0.001 is 2.78 x 10 to the minus 12th power square centimeters sr sec of 90% confidence level

Correlation of high energy muons with primary composition in extensive air shower

An experimental investigation of high energy muons above 200 GeV in extensive air showers has been made for studying high energy interaction and primary composition of cosmic rays of energies in the range 10 to the 14th power approx. 10 to the 15th power eV. The muon energies are estimated from the burst sizes initiated by the muons in the rock, which are measured by four layers of proportional counters, each of area 5 x 2.6 sq m, placed at 30 m.w.e. deep, Funasaka tunnel vertically below the air shower array. These results are compared with Monte Carlo simulations based on the scaling model and the fireball model for two primary compositions, all proton and mixed

A new ultra high energy gamma ray telescope at Ohya mine

The search for ultra high energy gamma rays coming from point sources is one of the main experimental aims. A fast air shower timing system was constructed at ICRR for the study of the angular resolution of the system and operated approximately half a year. The characteristics of the surface array of Ohya air shower telescope is described

Bacillus-Shaped Deposits Composed of Hexahedrally Based Crystals in Human Dental Calculus

In human supra- and subgingival calculus, bacillus-shaped deposits showing various rocky-pile forms composed of hexahedrally based crystals were observed by scanning electron microscopy. The crystal size measured approximately 0.1 - 1.5 μm. The electron probe microanalysis always detected calcium, phosphorous, and magnesium. Their molar ratios resembled those of magnesium-containing whitlockite and moreover the crystals also gave the electron diffraction pattern of whitlockite. The bacillus-shaped deposits happened to coexist with the intracellular calcifying microorganisms, furthermore, oral microorganisms partially replaced by the hexahedrally based crystals were found. The crystal deposits were never seen in the surface layers of calculus exposed to the oral cavity, but occurred in the innermost layers and intra-spaces of supragingival and ledge-type subgingival calculus and in the outer layers of deep subgingival calculus

Proportional drift tubes for large area muon detectors

A proportional drift chamber which consists of eight rectangular drift tubes with cross section of 10 cm x 5 cm, a sense wire of 100 micron phi gold-plated tungsten wire and the length of 6 m, was tested using cosmic ray muons. Spatial resolution (rms) is between 0.5 and 1 mm over drift space of 50 mm, depending on incident angle and distance from sense wire

Surface Chemical Reactions at the Atomic Scale: Gas Reactions with Semiconductors Studied with Scanning Tunneling Microscopy

The vacuum tunneling microscope has been extensively utilized in the study of the surface atomic configuration of conducting materials. Analysis of features in both the tunneling images and in the tunnel junction I-V characteristic yields insight into a wide variety of processes occurring at surfaces. In the last few years, elementary chemical reactions occurring at surfaces have been examined in this manner, principally adsorption of simple gas species such as H2, O2, and NH3 on semiconductors and metals. Adsorption sites have been deduced from changes brought about in surface configuration subsequent to gas exposure. The relationship of these sites with one another and their evolution as a function of exposure has been utilized to constrain mechanisms for the adsorption process. More recently, work has been performed where the scanning tunneling microscope (STM) takes on an active role. Hydrogen terminated silicon surfaces have been prepared and imaged with the STM. The tunneling images and infrared absorption spectra showed that configurations of both the terraces and steps are radically changed due to hydrogen capping. Moreover, the low-energy high-current density electron source, which is formed by the STM tip, has been used to selectively desorb this species from the surface. This process results in configuration changes which are derived from both the desorption kinetics and the long-range configuration of the initial surface