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T Yuda

Publications and source records attributed to T Yuda.

At least 19 recordsLinked to original sources
PubMed2006

Anisotropy and corotation of galactic cosmic rays.

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Journal Article↗
PubMed2004

Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.

Journal Article↗
PubMed2001

Growth and development in higher plants under simulated microgravity conditions on a 3-dimensional clinostat.

Growth and development of etiolated pea (Pisum sativum L. cv. Alaska) and maize (Zea mays L. cv. Golden Cross Bantam) seedlings grown under simulated microgravity conditions were intensively studied using a 3-dimensional clinostat as a simulator of weightlessness. Epicotyls of etiolated pea seedlings grown on the clinostat were the most oriented toward the direction far from cotyledons. Mesocotyls of etiolated maize seedlings grew at random and coleoptiles curved slightly during clinostat rotation. Clinostat rotation promoted the emergence of the 3rd internodes in etiolated pea seedlings, while it significantly inhibited the growth of the 1st internodes. In maize seedlings, the growth of coleoptiles was little affected by clinostat rotation, but that of mesocotyls was suppressed, and therefore, the emergence of the leaf out of coleoptile was promoted. Clinostat rotation reduced the osmotic concentration in the 1st internodes of pea seedlings, although it has little effect on the 2nd and the 3rd internodes. Clinostat rotation also reduced the osmotic concentrations in both coleoptiles and mesocotyls of maize seedlings. Cell-wall extensibilities of the 1st and the 3rd internodes of pea seedlings grown on the clinostat were significantly lower and higher as compared with those on 1 g conditions, respectively. Cell-wall extensibility of mesocotyls in seedlings grown on the clinostat also decreased. Changes in cell wall properties seem to be well correlated to the growth of each organ in pea and maize seedlings. These results suggest that the growth and development of plants is controlled under gravity on earth, and that the growth responses of higher plants to microgravity conditions are regulated by both cell-wall mechanical properties and osmotic properties of stem cells.

Biomechanical Phenomena↗
PubMed2001

Leaf senescence under various gravity conditions: relevance to the dynamics of plant hormones.

Effects of simulated microgravity and hypergravity on the senescence of oat leaf segments excised from the primary leaves of 8-d-old green seedlings were studied using a 3-dimensional (D) clinostat as a simulator of weightlessness and a centrifuge, respectively. During the incubation with water under 1-g conditions at 25 degrees C in the dark, the loss of chlorophyll of the segments was found dramatically immediately after leaf excision, and leaf color completely turned to yellow after 3-d to 4-d incubation. In this case kinetin (10 micromolar) was effective in retarding senescence. The application of simulated microgravity conditions on a 3-D clinostat enhanced chlorophyll loss in the presence or absence of kinetin. The loss of chlorophyll was also enhanced by hypergravity conditions (ca. 8 to 16 g), but the effect was smaller than that of simulated microgravity conditions on the clinostat. Jasmonates (JAs) and abscisic acid (ABA) promoted senescence under simulated microgravity conditions on the clinostat as well as under 1-g conditions. After 2-d incubation with water or 5-d incubation with kinetin, the endogenous levels of JAs and ABA of the segments kept under simulated microgravity conditions on the clinostat remained higher than those kept under 1-g conditions. These findings suggest that physiological processes of leaf senescence and the dynamics of endogenous plant hormone levels are substantially affected by gravity.

Abscisic Acid↗
PubMed2000

Surgical repair of a solitary deep femoral arterial aneurysm: report of two cases.

We report herein two cases of a solitary deep femoral arterial aneurysm that were successfully treated by aneurysmectomy and ligation of the deep femoral artery. The patients were a 69-year-old man and a 73-year-old man, both of whom presented with localized pain and a pulsatile mass in the femoral area showing rapid enlargement. Ultrasonography and arteriography confirmed the diagnosis and revealed no evidence of aneurysm or occlusive disease in the other arteries. Aneurysmectomy and ligation of the deep femoral artery were performed, and no ischemic symptoms or thrombus developed postoperatively in either patient. Preoperative arteriography is essential to delineate not only the state of the aneurysm, but also that of the distal arterial tree. An emergency operation is also mandatory due to the rapid enlargement of this type of aneurysm, even if rupture occurs.

Aged↗
PubMed2000

STS-95 space experiment for plant growth and development, and auxin polar transport.

The principal objective of the space experiment, BRIC-AUX on STS-95, was the integrated analysis of the growth and development of etiolated pea and maize seedlings in space, and the effect of microgravity conditions in space on auxin polar transport in the segments. Microgravity conditions in space strongly affected the growth and development of etiolated pea and maize seedlings. Etiolated pea and maize seedlings were leaned and curved during space flight, respectively. Finally the growth inhibition of these seedlings was also observed. Roots of some pea seedlings grew toward the aerial space of Plant Growth Chamber. Extensibilities of cell walls of the third internode of etiolated pea epicotyls and the top region of etiolated maize coleoptiles which were germinated and grown under microgravity conditions in space were significantly low. Activities of auxin polar transport in the second internode segments of etiolated pea seedlings and coleoptile segments of etiolated maize seedlings were significantly inhibited and extremely promoted, respectively, under microgravity conditions in space. These results strongly suggest that auxin polar transport as well as the growth and development of plants is controlled under gravity on the earth.

Biological Transport↗
PubMed2000

[Traumatic cardiac tamponade due to the nail stabbing].

A 45-year-old man was admitted to our hospital complaining of mild chest pain. The stab wound on the chest was very small and the nail had been completely buried under the skin. Emergency operation was mandatory for cardiac tamponade by the nail stabbing. Contused right ventricular wall was repaired using Teflon felt under cardiopulmonary bypass. It was important to have a suspicion as cardiac tamponade, when the patient showed uncertain hypotension.

Cardiac Tamponade↗
PubMed1999

Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array.

The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

Journal Article↗
PubMed1999

Growth and development, and auxin polar transport in higher plants under microgravity conditions in space: BRIC-AUX on STS-95 space experiment.

The principal objectives of the space experiment, BRIC-AUX on STS 95, were the integrated analysis of the growth and development of etiolated pea and maize seedlings in space and a study of the effects of microgravity conditions in space on auxin polar transport in these segments. Microgravity significantly affected the growth and development of etiolated pea and maize seedlings. Epicotyls of etiolated pea seedlings were the most oriented toward about 40 to 60 degrees from the vertical. Mesocotyls of etiolated maize seedlings were curved at random during space flight but coleoptiles were almost straight. Finally the growth inhibition of these seedlings in space was also observed. Roots of some pea seedlings grew toward to the aerial space of Plant Growth Chamber. Extensibilities of cell walls of the third internode of etiolated pea epicotyls and the top region of etiolated maize coleoptiles, which were germinated and grown under microgravity conditions in space, were significantly low as compared with those grown on the ground of the earth. Activities of auxin polar transport in the second internode segments of etiolated pea seedlings and coleoptile segments of etiolated maize seedlings were significantly inhibited and promoted, respectively, under microgravity conditions in space. These results strongly suggest that auxin polar transport as well as the growth and development of plants is controlled under gravity on the earth.

Biological Transport↗
PubMed1998

[Acute ventricular septal perforation in a patient with autoimmune hemolytic anemia].

A 71-year-old woman with autoimmune hemolytic anemia underwent an emergency endocardial patch repair for ventricular septal perforation after acute myocardial infarction. Use of washed red blood cells was effective in averting hemolytic crisis throughout perioperative period. In spite of improvement of her hemodynamics, liver dysfunction which had been present preoperatively deteriorated after the operation. Finally she died of hepatic failure on the 21st postoperative day. Deterioration of liver function could not be associated with autoimmune hemolytic anemia. To date, little information is available concerning the influence of cardiopulmonary bypass on hemolysis in patients with autoimmune hemolytic anemia. Therefore, prudent management and use of washed red blood cells transfusion would prevent hemolytic aggravation even in open heart surgery.

Acute Disease↗
PubMed1998

Pedicle transposition of the greater omentum for sternal osteomyelitis and mediastinitis after cardiac operation.

Three patients underwent pedicle transposition of the greater omentum for sternal osteomyelitis and mediastinitis after cardiac operation. These patients were previously operated on with coronary artery bypass grafting, aortic valve replacement and redo Fontan operation in each. This procedure was carried out on 4, 6, 8, and 14th postoperative day. The complications cured within about one month after the procedure in all cases. It is suggested that this maneuver is effective for obtaining healing osteomyelitis and mediastinitis following cardiac operation.

Adult↗
PubMed1997

[Retrieval of intravascular catheter fragment remaining for 15 years--a case report].

A 66-year-old woman was operated on aortic valve replacement, mitral valve replacement, and tricuspid annuloplasty. Retrieval of remaining Swan-Ganz Thermodilution catheter in the superior vena cava and the right atrium for 15 years was also made. Fortunately, contamination and embolism have not occurred for 15 years. Extracted catheter showed to be stiff due to the degradation. It was suggested that the cause of remaining was the thread for closing the left atrium on the previous operation. The explanation to patient and one's recognition are most important. We recommend that retrieval of remaining catheter for a long time and/or after open heart surgery should be made under extracorporeal circulation because that remaining catheter may be involved with the intima, and preventing from bleeding.

Aged↗
PubMed1997

[A surgical case of aortic valve stenosis associated with systemic lupus erythematosus].

A 46-year-old woman was hospitalized for aortic valve stenosis (AS) associated with systemic lupus erythematosus (SLE) on April 12, 1996. She had a syncopal episode six months before admission. She was found to have thrombocytopenia, and was diagnosed with SLE by further examination. Irregular genital bleeding was also seen on admission while her SLE was being controlled with steroid therapy. Aortic valve replacement was performed after the steroids had been reduced to avoid excessive bleeding. The aortic valve was the bicuspid with raphe. There was much calcification on the cusps and the annulus, but there were no degenerative changes. The postoperative course was uneventful, and her SLE has been in remission two years after the operation. The management of steroid therapy for SLE patients complicated with cardiovascular disease is discussed.

Aortic Valve Stenosis↗
PubMed1996

Right atrial mural thrombus associated with pericarditis.

A 33-year-old man was hospitalized with right heart failure. He was diagnosed as having right atrial mural thrombus complicated with pericarditis on echocardiography, thoracic computed tomography, and cardiac catheterization. Pericardiectomy and thrombectomy with a partial resection of the right atrial wall were performed under extracorporeal circulation. It was suggested that the cause of right atrial thrombus was congestion, atrial fibrillation, and pericarditis. The cause of pericarditis could not be determined by pathologic examination and laboratory data. Surgical treatment should be performed as soon as possible to prevent pulmonary embolism.

Adult↗
PubMed1996

Prolongation of liposome circulation time by various derivatives of polyethyleneglycols.

New lipid derivatives of polyethyleneglycol (PEG) have been synthesized and tested for the ability to allow liposomes to evade uptake by the reticuloendothelial system (RES) and to prolong the circulation time of liposomes in mice. Liposomes were prepared from distearoylphosphatidylcholine (DSPC) and cholesterol (CH) (1:1, m/m) containing 6 mol% of various PEG-derivatives. The activity of the CH derivative of PEG (CH-PEG) in prolonging the circulation time of liposomes was proportional to the average molecular weight of PEG, i.e., 4800 > 2600 > 1700 > 800. alpha-Methoxy-omega-(1,2-dioctadecenoyloxy glyceryl)polyoxyethylene (DO-PEG) 1000 and alpha-methoxy-omega-(1,2-ditetradecenoyloxy glyceryl) polyoxyethylene (DT-PEG) 1000, in which PEG is directly linked to glycerol, prolonged the circulation time as effectively as distearoylphosphatidyl-N-(methoxy polyoxyethylene succinyl)-ethanolamine (DSPE-PEG). PEG-derivatives with a functional group at the PEG terminal, such as distearoyl-phosphatidyl-N-(3-carboxypropionyl polyoxyethylene succinyl)ethanolamine (DSPE-PEG-COOH) and alpha-(dipalmitoylphosphatidyl)-omega-hydroxypolyoxyethylene (DPP-PEG-OH), effectively prolonged the circulation time of liposomes. Incorporation of PEG-derivatives did not change membrane fluidity even after treatment with serum. Furthermore, incorporation of PEG-derivatives into liposomes decreased uptake by J774 cells, a murine macrophage-like cell line, in vitro. The newly synthesized PEG-derivatives seem to prevent or reduce the interactions of liposomes with serum protein and macrophages, resulting in enhanced stability and a prolonged circulation time.

Animals↗
PubMed1996

[Use of the omentum for infected sternal dehiscence after aortic valve replacement--a case report].

A 68-year-old man had prosthetic valve replacement for aortic stenosis. Unfortunately, sternal dehiscence with osteomyelitis occurred on the fifth postoperative day. Implantation of the pedicled omentum to the wound was carried out three days later. The result was excellent. This is the worthy method to try to such wound of infected sternum with dehiscence. From the point of view of anatomy and physiology, the omentum has a great benefit to repair the infected space and promote the wound healing process.

Aged↗
PubMed1996

[Re-do Fontan operation--a case report].

A 32-year-old woman developed heart failure. She had received Glenn operation 26 years ago and Fontan operation using valved conduit (Björk-Shiley: 21 mm) seven years ago for tricuspid atresia type 1b. She underwent extirpation of the struck prosthetic valve. Neither graft stenosis nor pressure gradient between the right atrium and the pulmonary artery were observed on postoperative right arteriography. Sternotomy on redo Fontan operation should be carefully performed for preventing breaking down the implanted valved conduit. Though the prosthetic valve was not necessary on redo Fontan operation, anticoagulation after operation should be done.

Adult↗