Estimating the mass of asteroid 253 mathilde from tracking data during the NEAR flyby   总被引：1，自引：0，他引：1  

DK Yeomans  J Barriot  DW Dunham  RW Farquhar  JD Giorgini  CE Helfrich  AS Konopliv  JV McAdams  JK Miller  WM Owen  DJ Scheeres  SP Synnott  BG Williams 《Science (New York, N.Y.)》1997,278(5346):2106-2109

The terminal navigation of the Near Earth Asteroid Rendezvous (NEAR) spacecraft during its close flyby of asteroid 253 Mathilde involved coordinated efforts to determine the heliocentric orbits of the spacecraft and Mathilde and then to determine the relative trajectory of the spacecraft with respect to Mathilde. The gravitational perturbation of Mathilde on the passing spacecraft was apparent in the spacecraft tracking data. As a result of the accurate targeting achieved, these data could be used to determine Mathilde's mass as 1.033 (+/- 0.044) x 10(20) grams. Coupled with a volume estimate provided by the NEAR imaging team, this mass suggests a low bulk density for Mathilde of 1.3 grams per cubic centimeter.  相似文献   

Genetic diversity among Japanese local populations of an edible and medicinal coastal plant Glehnia littoralis F. Schmidt ex Miq.     

Tamura  Yasuhiro  Kubo  Nakao  Ohsako  Takanori 《Genetic Resources and Crop Evolution》2022,69(1):85-97

Genetic Resources and Crop Evolution - To assess the current genetic status of a useful coastal plant Glehnia littoralis F. Schmidt ex Miq. in Japan, the genetic diversity within and among natural...  相似文献   

Genetic mechanisms of postzygotic reproductive isolation: An epistatic network in rice     

Takahiko Kubo 《Breeding Science》2013,63(4):359-366

Products of interspecific crosses often show abnormal phenotypes such as sterility, weakness and inviability. These phenomena play an important role in speciation as mechanisms of postzygotic reproductive isolation (RI). During the past two decades, genetics studies in rice have characterized a number of gene loci responsible for postzygotic RI. I have identified 10 loci including three sets of epistatic networks in a single inter-subspecific cross (Oryza sativa ssp. indica × japonica). These results suggest that RI genes cause developmental dysfunction of vegetative and/or reproductive organs through a variety of molecular pathways. The latest molecular studies demonstrated that hybrid incompatibility is mainly due to deleterious interactions caused by species-specific mutations of two or more genes, mediated by proteins acting within the same molecular pathway. Because genetic interactions provide a perspective on gene function, epistatic networks are a key to the understanding of the molecular basis of postzygotic RI. In this review, I focus on recent progress in postzygotic RI studies in rice and discuss the evolutionary significance as well as implications for improving rice productivity.  相似文献   

Acute small intestinal obstruction associated with Parascaris equorum infection in young horses: 25 cases (1985–2004)     

NC Cribb  NM Coté  LP Bouré  AS Peregrine 《New Zealand veterinary journal》2013,61(6):338-343

AIMS: To retrospectively evaluate the medical and surgical records of horses with acute small intestinal obstructions associated with Parascaris equorum infection; to describe the gastrointestinal lesions; and to determine the outcome of cases with such lesions.

METHODS: Records of 25 horses with acute small intestinal obstruction associated with P. equorum between 1985 and 2004 were reviewed to determine signalment, history, physical examination, surgical or post-mortem findings, and outcome.

RESULTS: All horses except one were less than 12 months old. Standardbreds were over-represented in the population studied. Sixteen horses (72%) had been administered anthelmintics, including pyrantel (n=8), ivermectin (n=7), and trichlorphon (n=1), within 24 h prior to the onset of colic. Of the 25 cases reviewed, 16 had simple obstructive ascarid impactions (SOAIs), and nine had complicated obstructive ascarid impaction (COAI) including volvulus (n=6) or intussusception (n=3), both concurrent with ascarid impaction of the small intestine. Short-term survival (discharge from hospital) occurred in 79% of horses treated for SOAI, and was 64% for all horses. Long-term survival (>1 year) occurred in 33% of horses with SOAI, and the overall long-term survival was 27% for all horses. Formation of adhesions was the most frequent finding associated with death for horses that did not survive long-term.

CONCLUSIONS AND CLINICAL RELEVANCE: The incidence of anthelmintic treatment within 24 h of the onset of colic in this study population (72%) was higher than that previously reported. Resistance of P. equorum to ivermectin recently reported in Ontario may be associated with increased ascarid burdens, predisposing horses to ascarid impaction. The long-term survival of these horses was better than that reported previously.  相似文献   

Operation of the Ba Lai irrigation system in the Mekong Delta, Vietnam     

Quang Huy Hoang  Naritaka Kubo  Ngan Giang Hoang  Hajime Tanji 《Paddy and Water Environment》2009,7(2):123-133

Ba Lai Irrigation Project is located at coastal area in the Mekong Delta. In dry season when the flow rate decreases and the strong east wind blows into the delta, the salinity intrusion increases and seriously affects agricultural and domestic water use. Intakes of Ba Lai system have to be closed for 1–3 months depending on their locations, and no water supply during this period often causes water pollution in the project area. In order to solve such problems, this study aims to seek gate operation procedures for salinity control and water environment improvement. A numerical model is developed to simulate water movement, salinity concentration and duration of remaining water (water age) within the system under three scenarios: (1) without control structures, (2) with available control structures, (3) with the full control structures. Through the numerical simulations, control structures are confirmed to be an effective measure for the salinity control and suitable gate operation schedules are proposed to improve the water environment in the project.  相似文献   

Chemotherapy for dogs with lymph node metastasis from histiocytic sarcomas          下载免费PDF全文

AS Moore  DP Taylor  G Reppas  AE Frimberger 《Australian veterinary journal》2017,95(1-2):37-40

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Comparison between indocyanine green angiography and fluorescein angiography in normal cats          下载免费PDF全文

Miri Hayashi  Seiya Maehara  Yosuke Ito  Kazuto Yamashita  Akira Kubo  Tetsuya Nakade 《Veterinary ophthalmology》2017,20(4):310-315

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Molecular mapping of a gene conferring resistance to Aphanomyces root rot (black root) in sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.)     

Kazunori Taguchi  Kazuyuki Okazaki  Hiroyuki Takahashi  Tomohiko Kubo  Tetsuo Mikami 《Euphytica》2010,173(3):409-418

Caused by Aphanomyces cochlioides Drechsler, Aphanomyces root rot is a serious disease of sugar beet (Beta vulgaris L.), for which sources of resistance are scarce. To identify the segregation pattern of the rare resistance trait found in Japanese sugar beet line ‘NK-310mm-O’, F₁ and BC₁F₂ seedings, drawn from a cross between ‘NK-310mm-O’ and susceptible line ‘NK-184mm-O’, were inoculated with zoospores and their survival evaluated in the greenhouse. Resistance segregation followed was that of a single dominant gene, which was designated Acr1 (Aphanomyces cochlioides resistance 1). Molecular markers tightly linked to Acr1 were identified by bulked segregant analysis of two BC₁F₂ populations. Fourteen AFLP markers linked to Acr1 were identified, the closest located within ±3.3 cM. Three F₅ lines and two BC₂F₁ lines, selected on the basis of their Acr1-AFLP markers, were tested for their resistance to Aphanomyces root rot in a highly infested field. Results indicated that Acr1 conferred significant resistance to Aphanomyces root rot at the field level. Based on its linkage with CAPS marker tk, a representative marker for chromosome III, Acr1 was located on this chromosome. The clear linkage between tk and Rhizomania resistance trait Rz1, suggests the clustering of major disease resistance genes on chromosome III.  相似文献   

CMA staining analysis of chromosomes in several species of Aurantioideae     

Masashi Yamamoto  Asad Asadi Abkenar  Ryoji Matsumoto  Tatsuya Kubo  Shigeto Tominaga 《Genetic Resources and Crop Evolution》2008,55(8):1167-1173

Fluorochrome staining with chromomycin A₃ (CMA) was used to characterize and compare the CMA banding patterns of chromosomes of 17 species from 13 genera of Aurantioideae, which is one of the seven subfamilies of Rutaceae. All species used in this study had 2n = 18 chromosomes. These chromosomes were classified into five types based on the number and position of CMA-positive bands; B: one telomeric and one proximal band, C: two telomeric bands, D: one telomeric band, E: without bands and Dst: type D with a satellite chromosome. Each species possessed two or four types of chromosomes and unique CMA banding patterns. The CMA banding patterns were 6D + 12E in Clausena anisata (Willd.) Hook. f.,1C + 3D + 14E in Murraya koenigii (L.) Spreng., 1C + 11D + 6E in Murraya paniculata (L.) Jack, 1B + 1C + 10D + 6E in Merrillia caloxylon (Ridl.) Swing., 1C + 9D + 7E + 1Dst in Paramignya lobata Burkill, 2C + 5D + 11E in Severinia buxifolia (Poir.) Tenore, 5D + 13E in Hesperethusa crenulata (Roxb.) Roem., 16D + 2E in Citropsis gabunensis (Engl.) Swing. et M. Kell, 14D + 4E in Citropsis schweinfurthii (Engl.) Swing. et M. Kell, 8D + 10E in Atalantia monophylla DC., 1C + 3D + 14E in Atalantia ceylanica (Arn.) Oliv., 2D + 16E in Atalantia roxburghiana Hook. f., 18E in Swinglea glutinosa (Blanco) Merr., 2D + 16E in Aegle marmelos (L.) Corr., 4D + 14E in Afraegle paniculata (Schum.) Engl., 2B + 2D + 13E + 2Dst in Feronia limonia (L.) Swing. and 3B + 9D + 6E in Feroniella oblata Swing. The advanced genera in each tribe and subtribe such as Merrillia and Feroniella showed heterochromatin (CMA-positive bands) rich chromosome configuration in general. Swinglea glutinosa without heterochromatin rich chromosome, which is considered to be the most primitive chromosome configuration, seems to be the key genus for clarifying the evolution of the tribe Citreae.  相似文献   

Effects of water on the alpha-beta transformation kinetics in san carlos olivine   总被引：3，自引：0，他引：3  

T Kubo  E Ohtani  T Kato  T Shinmei  K Fujino 《Science (New York, N.Y.)》1998,281(5373):85-87

In experiments at 13.5 gigapascals and 1030 degreesC, the growth rate of wadsleyite, which forms from transformation of olivine, was substantially enhanced by the presence of water. Wadsleyite had a low dislocation density and subgrain boundaries in wet runs. Water enhanced the dislocation recovery in wadsleyite and therefore caused inelastic relaxation of the localized pressure drop associated with the transformation, resulting in an increase of the growth rate in wet runs. These results imply that even a small amount of water of 0. 05 weight percent can weaken wadsleyite in the mantle.  相似文献