An extremely luminous panchromatic outburst from the nucleus of a distant galaxy     

Levan AJ  Tanvir NR  Cenko SB  Perley DA  Wiersema K  Bloom JS  Fruchter AS  Postigo Ade U  O'Brien PT  Butler N  van der Horst AJ  Leloudas G  Morgan AN  Misra K  Bower GC  Farihi J  Tunnicliffe RL  Modjaz M  Silverman JM  Hjorth J  Thöne C  Cucchiara A  Cerón JM  Castro-Tirado AJ  Arnold JA  Bremer M  Brodie JP  Carroll T  Cooper MC  Curran PA  Cutri RM  Ehle J  Forbes D  Fynbo J  Gorosabel J  Graham J  Hoffman DI  Guziy S  Jakobsson P  Kamble A  Kerr T  Kasliwal MM  Kouveliotou C  Kocevski D  Law NM  Nugent PE  Ofek EO  Poznanski D 《Science (New York, N.Y.)》2011,333(6039):199-202

Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source. We pinpoint the event to the center of a small, star-forming galaxy at redshift z = 0.3534. Its high-energy emission has lasted much longer than any γ-ray burst, whereas its peak luminosity was ～100 times higher than bright active galactic nuclei. The association of the outburst with the center of its host galaxy suggests that this phenomenon has its origin in a rare mechanism involving the massive black hole in the nucleus of that galaxy.  相似文献   

泸州荔枝果园AM真菌菌根及孢子数量调查与分析   总被引：1，自引：0，他引：1  

姜国金  许兰珍  杨晓红  王容春  朱邦松 《安徽农业科学》2007,35(22):6701-6702

[目的]对泸州荔枝园AM真菌进行调查,确认荔枝菌根类型,了解果园土壤中AM真菌孢子种群数量的大致情况。[方法]利用"湿筛法"和Phllips&Hayman的方法对3个泸州荔枝果园春季的土壤AM真菌进行了调查分析。[结果]荔枝菌根是内生菌根,共生真菌为囊泡——丛枝菌根真菌,即AM真菌。春季的菌根感染率在9%~32%之间,普遍低于25%。VA菌根感染率的平均值在15%~21%之间,低于25%。三个荔枝园每25 g土样中AM真菌孢子数平均值为869±76个。[结论]果园生草或对果园进行有机覆盖,是促进荔枝生长,增加荔枝果实产量,改善荔枝果实品质的一种绿色环保途径。  相似文献   

Local Control of Microdomain Orientation in Diblock Copolymer Thin Films with Electric Fields     

TL Morkved  M Lu  AM Urbas  EE Ehrichs  HM Jaeger  P Mansky  TP Russell 《Science (New York, N.Y.)》1996,273(5277):931-933

Local control of the domain orientation in diblock copolymer thin films can be obtained by the application of electric fields on micrometer-length scales. Thin films of an asymmetric polystyrene-polymethylmethacrylate diblock copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned with planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation of the electrodes and the copolymer domain structure by transmission electron microscopy. The cylinders aligned parallel to the electric field lines for fields exceeding 30 kilovolts per centimeter, after annealing at 250°C in an inert atmosphere for 24 hours. This technique could find application in nanostructure fabrication.  相似文献   

Neutron imaging of laser fusion targets     

Ress D  Lerche RA  Ellis RJ  Lane SM  Nugent KA 《Science (New York, N.Y.)》1988,241(4868):956-958

Along-term goal of inertial-confinement fusion research is the generation of energy by imploding capsules containing deuterium-tritium fuel. Progress in designing the capsules is aided by accurate imaging of the fusion burn. Penumbral coded-aperture techniques have been used to obtain neutron images that are a direct measurement of the fusion burn region in the capsules.  相似文献   

Controlled pollination transfer of a nuclear male-sterile gene from a diploid to a tetraploid watermelon line     

S. L. Love  B. B. Rhodes  P. E. Nugent 《Euphytica》1986,35(2):633-638

Summary A recessive male-sterility (ms) gene was transferred from a diploid to a tetraploid watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai) line through a series of controlled pollinations. Progeny testing and morphological characteristics confirmed the development of tetraploid lines containing the ms gene. The possible use of this gene transfer system in the improvement of tetraploid watermelon cultivars and the use of male-sterile tetraploids in the production of seedless triploid watermelons is discussed.  相似文献   

Amplification of acidic protease virulence gene (aprV2) in samples from footrot lesions did not help in diagnosis of clinical virulent footrot in affected sheep flocks in New South Wales     

AM Collins  BG Bowring 《Australian veterinary journal》2020,98(7):298-304

  相似文献   

Mycobacterium avium subsp. paratuberculosis infection in wildlife on three deer farms with a history of Johne's disease     

Nugent G  Whitford EJ  Hunnam JC  Wilson PR  Cross M  de Lisle GW 《New Zealand veterinary journal》2011,59(6):293-298

  相似文献   

Last occurrence and survival during winter of the arbovirus vector Culicoides brevitarsis at the southern limits of its distribution     

AL BISHOP  IM BARCHIA  AM HARRIS 《Australian veterinary journal》1995,72(2):53-55

SUMMARY: Linear regression analysis was used to describe the decline in numbers of Culicoides brevitarsis Kieffer into winter with monthly maximum, average and minimum temperatures at the southern limits to its distribution in New South Wales. From this, low temperature thresholds were derived when C brevitarsis would be absent from the field. The low minimum threshold ± 2 SE (95% Confidence Interval) of 8.1 ± 0.3°C was used with historical temperature data to estimate the last month that the species should occur (March to June) and the mean number of months (2 to 6.5) below the threshold at 17 selected sites. Probability for survival during winter at these sites was estimated from years when the number of consecutive months below the threshold was ≤ 2 months. This varied from zero to 51% depending on the location of the site. Last occurrence was 0.7 months later on average and absolute probabilities for survival ranged from zero to 100% when the temperatures were increased by an arbitrary 2°C.  相似文献   

Association of avian reovirus M and S genes with viral behavior in vivo. I. Viral persistence   总被引：1，自引：0，他引：1  

D D Huang  M A Nugent  J K Rosenberger  T J Schnitzer 《Avian diseases》1987,31(3):438-445

Persistent infections were initiated in chickens with four different avian reovirus strains of varying virulence. Chickens 1 day old, 1 week old, or 2 weeks old were inoculated with each. Eight weeks later, isolates from all four parent strains were obtained; all isolates but one were from the tendons, and that was from the pancreas. Biochemical characterization of the isolates showed their genomes to be similar to those of the parent strains, although the proteins of the persistent isolates occasionally appeared to migrate differently from those of the original strains. Hybridization studies of the genes of the isolates indicated that at least two genes, S2 and S4, consistently seemed to undergo the greatest degree of mutation in the most virulent strain. These data suggest that the S2 and S4 genes may be associated with initiation and maintenance of persistent infection in vivo, and that changes in these genes may be noted by 56 days postinfection.  相似文献   

Use of magnetic particles to improve the diagnosis of sheep-associated malignant catarrhal fever by polymerase chain reaction     

TM ELLIS  AM MASTERS 《Australian veterinary journal》1997,75(7):520-521

  相似文献