Simulation of femtosecond "double-slit" experiments for a chromophore in a dissipative environment.

We performed simulations of the prototypical femtosecond "double-slit" experiment with strong pulsed laser fields for a chromophore in solution. The chromophore is modeled as a system with two electronic levels and a single Franck-Condon active underdamped vibrational mode. All other (intra- and inter-molecular) vibrational modes are accounted for as a thermal bath. The system-bath coupling is treated in a computationally accurate manner using the hierarchy equations of motion approach. The double-slit signal is evaluated numerically exactly without invoking perturbation theory in the matter-field interaction. We show that the strong-pulse double-slit signal consists of a superposition of N-wave-mixing (N = 2, 4, 6...) responses and can be split into population and coherence contributions. The former reveals the dynamics of vibrational wave packets in the ground state and the excited electronic state of the chromophore, while the latter contains information on the dephasing of electronic coherences of the chromophore density matrix. We studied the influence of heat baths with different coupling strengths and memories on the double-slit signal. Our results show that the double-slit experiment performed with strong (nonperturbative) pulses yields substantially more information on the photoinduced dynamics of the chromophore than the weak-pulse experiment, in particular, if the bath-induced dephasings are fast.

DEVELOPMENT OF A HIGH-EFFICIENCY PROTON RECOIL TELESCOPE FOR D-T NEUTRON FLUENCE MEASUREMENT.

A high-efficiency proton recoil telescope was developed to determine neutron fluences in neutron fields using the 3H(d,n)4He reaction. A 2-mm thick plastic scintillation detector was employed as a radiator to increase the detection efficiency and compensate for the energy loss of the recoil proton within. Two silicon detectors were employed as the ΔE and E detectors. The distance between the radiator and the E detector was varied between 50 and 150 mm. The telescope had detection efficiencies of 3.5 × 10-3 and 7.1 × 10-4 cm2 for distances of 50 and 100 mm, respectively, which were high enough to determine the neutron fluence in 14.8-MeV neutron fields, with a few thousand cm-2 s-1 fluence rate, within a few hours.

Construction of monoenergetic neutron calibration fields using 45Sc(p, n)45Ti reaction at JAEA.

The 8 and 27 keV monoenergetic neutron calibration fields have been developed by using (45)Sc(p, n)(45)Ti reaction. Protons from a 4-MV Pelletron accelerator are used to bombard a thin scandium target evaporated onto a platinum disc. The proton energies are finely adjusted to the resonance to generate the 8 and 27 keV neutrons by applying a high voltage to the target assemblies. The neutron energies were measured using the time-of-flight method with a lithium glass scintillation detector. The neutron fluences at a calibration point located at 50 cm from the target were evaluated using Bonner spheres. A long counter was placed at 2.2 m from the target and at 60 degrees to the direction of the proton beam in order to monitor the fluence at the calibration point. Fluence and dose equivalent rates at the calibration point are sufficient to calibrate many types of the neutron survey metres.

Investigation of properties of the TIARA neutron beam facility of importance for calibration applications.

Evaluation of the properties for quasi-monoenergetic neutron calibration fields of high energies more than 20 MeV at TIARA is proceeding for development of the field. Among the properties needed for the development as the standard calibration field, we report on measurement of the neutron beam profile using an imaging plate with a polyethylene converter and on estimation of the contribution of scattered neutrons into the irradiation field based on pulse height distribution at various off-beam positions measured using an organic liquid scintillation detector.

Hemangioblastoma of the central nervous system: nature of the stromal cells as studied by the immunoperoxidase technique.

Ten hemangioblastomas of the central nervous system were examined by an immunoperoxidase technique for glial fibrillary acidic protein (GFAP), S-100 protein, and Factor VIII-related antigen to determine the origin of the stromal cells. In seven cases scattered stromal cells were positive for GFAP, and eight cases showed variable numbers of S-100 protein-positive cells. These positive cells were present throughout the tumors. S-100 protein-positive stromal cells corresponded to GFAP-positive cells, but the former were more numerous than the latter. Staining for Factor VIII-related antigen was negative in stromal cells, except in endothelial cells lining capillaries. It was suggested that stromal cells of capillary hemangioblastomas are composed by heterogeneous cell populations.

Primary choriocarcinoma of the lung.

Choriocarcinoma was found in the lung of a 34-year-old woman. Examination of the patient's entire body, especially the genital tract, failed to disclose foci of choriocarcinoma other than that in the right lung. After surgery, the levels of human chorionic gonadotropin in the blood and the urine fell. It was concluded that the choriocarcinoma of the lung was, in fact, the primary tumor. The genesis of choriocarcinoma was also studied in ten patients who died after delivery or abortion. Autopsy disclosed trophoblasts in the pulmonary arteries in nine of these ten patients. These findings suggest that primary choriocarcinoma in women is due to pulmonary embolism caused by trophoblasts at the time of abortion or delivery.

Heme-copper oxidase family structure of Magnetospirillum magnetotacticum 'cytochrome a1'-like hemoprotein without cytochrome c oxidase activity.

The genes encoding 'cytochrome a1'-like hemoprotein of Magnetospirillum magnetotacticum were identified and sequenced. Three ORFs, mcalI, mcaI and hosA, were included in the sequenced region. The six histidine residues which were predicted to associate with the prosthetic cofactors of heme-copper oxidase superfamily were conserved in the hemoprotein. However, none of the amino acid residues which were proposed to participate in the oxygen-reducing and the coupled proton pumping reactions in cytochrome c oxidase were at all conserved in the hemoprotein.

Two human papillomavirus DNAs molecularly cloned from a patient with epidermodysplasia verruciformis: restriction maps.

Two distinct human papillomavirus (HPV) DNAs (MY-1 and MY-2) were molecularly cloned from the benign skin lesions of a patient with epidermodysplasia verruciformis. The restriction map of MY-1 was the same as that of HPV 3a. The map of MY-2 appeared to be different from those of any HPVs reported in the literature. MY-2 did not cross-hybridize with MY-1 or the DNAs of HPV types 1, 2 and 4 under stringent conditions.

Risk factors for falls among blind elderly in a nursing home for the blind.

The present study is a retrospective investigation of falls and the risk factor for falls among 84 blind elderly residents of a nursing home for the blind over a period of 2 years. During these 2 years, 20 residents (24%) experienced falls, and 6 (7%) of them sustained bone fractures. An investigation of risk factors for falls revealed a relation between falls and depressive symptoms, a deterioration in the sense of balance, and presbyacusis. Due to the heightened risk of falls among the visually handicapped, sufficient attention must be paid to signs of depression, decline of balance, and presbyacusis in the care of the blind elderly.

Conceptual design of spectrum changeable neutron calibration fields in JAERI/FRS.

Spectrum changeable neutron calibration fields are planned to be established with an accelerator installed in Japan Atomic Energy Research Institute/Facility of Radiation Standards. The neutron fields are provided by bombarding a target surrounded by a moderator, with charged particles from the accelerator. In the fields, a wide variety of neutron spectra is provided with sufficient fluence rate for the calibration of dosemeters. In this study, necessity of the field was first discussed in view of relationship between readings of existing dosemeters and true dose equivalents where the dosemeters were used. Second, test simulation of neutron spectra was carried out with the Monte Carlo technique for some arrangements with a LiF target and quasi-cylindrical moderators with different materials. The simulated spectra were summarised in terms of fluence-average energy, fluence rate and calibration factor for the dosemeters.

Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI.

The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.

Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI.

Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.

[Polychlorinated biphenyls (PCBs) and polychlorinated quaterphenyls (PCQs) concentrations in skin surface lipids and blood of patients with Yusho].

The relationship between Polychlorinated Biphenyls (PCBs), and Polychlorinated Quaterphenyls (PCQs) concentrations in the skin surface lipids and blood was investigated in twenty two patients with PCB poisoning (Yusho) and 9 control subjects were analyzed. The collection of skin surface lipids was performed by the method of cotton pad with 70% ethyl alcohol. The alkaline decomposition method described as "the official standard analytical methods for the isolation of PCBs and PCQs fractions" was used. In the blood of control group, the mean value of PCBs concentration was 1.8 ng/g, and that of PCQs concentration was very low and undetectable by our analytical method. On the other hand, the PCBs concentration in the Yusho group was three times higher than those in the control group. The mean value of PCQs concentration was 1.90 ng/g in Yusho group, while it was not detectable in the control group. In the skin surface lipids of patients with Yusho, the mean value of PCBs concentration was 668.6 ng/g, but was 256.7 ng/g in the control group. The mean value of PCQs concentration in the skin surface lipids of Yusho patients was 35.4 ng/g, although it was not detected in the control group. These values of the skin surface lipids in 1993 were decreased as compared with those in 1992. PCBs and PCQs levels in the skin surface lipids were higher than those in the blood. These findings suggests that cutaneous sebaceous system is one of the excretory systems of polyhalogenated chemicals, such as PCBs or PCQs, when these chemicals are precipitated in human or mammalian.

An attempt to decrease anisotropic emissions of neutrons from a cylindrical 241Am-Be-encapsulation source.

An attempt to decrease the anisotropic emissions of neutrons from a cylindrical (241)Am-Be-encapsulated X3 source was conducted with Monte Carlo calculations and experiments. The influence of metal materials and shapes of the external casing to the anisotropy factor were focussed on. Results obtained by calculations using MCNP4C implied that a light and spherical-shaped external casing decreases the anisotropic emission of neutrons. Experimental results using the spherical-shaped aluminium protection case also revealed that the anisotropy factor was close to 1.0 with wide zenith angle ranges.

Photon dose mixed in monoenergetic neutron calibration fields using 7Li(p,n)7Be reaction.

The ambient dose equivalents H*(10) of photons mixed in the 144, 250 and 565 keV monoenergetic neutron fields were evaluated using measurements from an NaI(Tl) detector and calculations done using the MCNP-ANT code. It was found that H*(10) of the photons produced in the target assembly dominates the dose, particularly near the target. The H*(10) of the photons produced in other materials in the field increases with the increase in distance from the target and could not be neglected at a large distance from the target. The ratios of the H*(10) of the mixed photons to that of the monoenergetic neutrons for 144, 250 and 565 keV neutron fields, were evaluated to be below 5.5, 6.9 and 1.5 %, respectively. The ratios were calculated at calibration points between 100 and 500 cm from the target.

Development of portable long counter with two different moderator materials.

A portable, light-weight long counter (LC) with small dimensions was developed. This LC consists of a (3)He thermal neutron counter, a cylindrical moderator and outer shields. It was designed to have an almost flat response in a neutron energy range of 0.4 eV to 5 MeV. The portable LC has a radius of 11 cm and a length of 39 cm. Its weight was successfully reduced to 15 kg. Polystyrene was employed instead of polyethylene for the front part of the moderator in order to increase the sensitivity to low-energy neutrons. The response function calculated using the MCNP code was consistent with the results of experiments using monoenergetic neutron calibration fields.

Exercise-induced muscle damage impairs insulin signaling pathway associated with IRS-1 oxidative modification.

Strenuous exercise induces delayed-onset muscle damage including oxidative damage of cellular components. Oxidative stress to muscle cells impairs glucose uptake via disturbance of insulin signaling pathway. We investigated glucose uptake and insulin signaling in relation to oxidative protein modification in muscle after acute strenuous exercise. ICR mice were divided into sedentary and exercise groups. Mice in the exercise group performed downhill running exercise at 30 m/min for 30 min. At 24 hr after exercise, metabolic performance and insulin-signaling proteins in muscle tissues were examined. In whole body indirect calorimetry, carbohydrate utilization was decreased in the exercised mice along with reduction of the respiratory exchange ratio compared to the rested control mice. Insulin-stimulated uptake of 2-deoxy-[(3)H]glucose in damaged muscle was decreased after acute exercise. Tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and phosphatidyl-3-kinase/Akt signaling were impaired by exercise, leading to inhibition of the membrane translocation of glucose transporter 4. We also found that acute exercise caused 4-hydroxy-nonenal modification of IRS-1 along with elevation of oxidative stress in muscle tissue. Impairment of insulin-induced glucose uptake into damaged muscle after strenuous exercise would be related to disturbance of insulin signal transduction by oxidative modification of IRS-1.