The radio-frequency single-electron transistor (RF-SET): A fast and ultrasensitive electrometer     

RJ Schoelkopf  P Wahlgren  AA Kozhevnikov  P Delsing  DE Prober 《Science (New York, N.Y.)》1998,280(5367):1238-1242

A new type of electrometer is described that uses a single-electron transistor (SET) and that allows large operating speeds and extremely high charge sensitivity. The SET readout was accomplished by measuring the damping of a 1.7-gigahertz resonant circuit in which the device is embedded, and in some ways is the electrostatic "dual" of the well-known radio-frequency superconducting quantum interference device. The device is more than two orders of magnitude faster than previous single-electron devices, with a constant gain from dc to greater than 100 megahertz. For a still-unoptimized device, a charge sensitivity of 1.2 x 10(-5) e/hertz was obtained at a frequency of 1.1 megahertz, which is about an order of magnitude better than a typical, 1/f-noise-limited SET, and corresponds to an energy sensitivity (in joules per hertz) of about 41 Planck's over 2pi.  相似文献   

Biomass as a source of chemical feedstocks: an economic evaluation     

Palsson BO  Fathi-Afshar S  Rudd DF  Lightfoot EN 《Science (New York, N.Y.)》1981,213(4507):513-517

It is suggested that the raw materials and technology exist for basing a major fraction of the U.S. chemical industry on four fermentation products, used in the proper portions: ethanol, isopropanol, n-butanol, and 2,3-butanediol. The primary route for introduction of these materials is dehydration of the alcohols and diols to olefins, which would cause little disruption of the existing industry downstream from the olefins. The proposed substitution has the advantages that it would provide a smooth transition toward renewable feedstocks, while decreasing dependence on fossil sources of organic material and use of toxic materials. However, to make these materials attractive as feedstocks or intermediates in chemical production, their current prices must be substantially reduced. Even with the optimum mix, their largeseale utilization will only occur at about 20 to 40 percent of their estimated chemical prices.  相似文献   

Genomic and genetic definition of a functional human centromere   总被引：1，自引：0，他引：1  

Schueler MG  Higgins AW  Rudd MK  Gustashaw K  Willard HF 《Science (New York, N.Y.)》2001,294(5540):109-115

The definition of centromeres of human chromosomes requires a complete genomic understanding of these regions. Toward this end, we report integration of physical mapping, genetic, and functional approaches, together with sequencing of selected regions, to define the centromere of the human X chromosome and to explore the evolution of sequences responsible for chromosome segregation. The transitional region between expressed sequences on the short arm of the X and the chromosome-specific alpha satellite array DXZ1 spans about 450 kilobases and is satellite-rich. At the junction between this satellite region and canonical DXZ1 repeats, diverged repeat units provide direct evidence of unequal crossover as the homogenizing force of these arrays. Results from deletion analysis of mitotically stable chromosome rearrangements and from a human artificial chromosome assay demonstrate that DXZ1 DNA is sufficient for centromere function. Evolutionary studies indicate that, while alpha satellite DNA present throughout the pericentromeric region of the X chromosome appears to be a descendant of an ancestral primate centromere, the current functional centromere based on DXZ1 sequences is the product of the much more recent concerted evolution of this satellite DNA.  相似文献   

Oceanic Anoxia and the End Permian Mass Extinction   总被引：6，自引：0，他引：6  

PB Wignall  RJ Twitchett 《Science (New York, N.Y.)》1996,272(5265):1155-1158

Data on rocks from Spitsbergen and the equatorial sections of Italy and Slovenia indicate that the world's oceans became anoxic at both low and high paleolatitudes in the Late Permian. Such conditions may have been responsible for the mass extinction at this time. This event affected a wide range of shelf depths and extended into shallow water well above the storm wave base.  相似文献   

Arthropod-transmitted infectious diseases of cats     

SE Shaw  RJ Birtles  MJ Day 《Journal of Feline Medicine and Surgery》2001,3(4):193-209

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Family-based QTL mapping of heat stress tolerance in primitive tetraploid wheat (Triticum turgidum L.)     

Mohamed B. Ali  Amir M. H. Ibrahim  Subas Malla  Jackie Rudd  Dirk B. Hays 《Euphytica》2013,192(2):189-203

Identification of quantitative trait loci (QTL) and markers associated with heat and drought tolerance is warranted for marker-assisted selection in wheat (Triticum aestivum L.) breeding programs in areas prone to these abiotic stresses. Our study used a family-based mapping approach in which 19 families consisting of 384 individuals were developed by three-way crosses involving the heat tolerant, tetraploid cultivated emmer (Triticum turgidum L. var dicoccum) genotype IG45069 and ten heat susceptible tetraploid genotypes, IG44999, IG44961, IG45413, IG83047, IG45441, IG127682, IG45448, IG110572, IG88723 and IG54073, in order to detect QTL and markers associated with heat tolerance. The 384 individuals were phenotyped for physiological traits associated with heat tolerance and genotyped by SSR markers. The QTL associated with heat stress tolerance, as measured by chlorophyll content, flag leaf temperature depression (FLTD) and individual kernel weight (IKW) were mapped on chromosomes 1B (QChlc.tamu-1B), 2B (QFlt.tamu-2B), and 5A (QIkw.tamu-5A), respectively, using linkage analysis. Alleles from IG45069 possessed the highest associations with the phenotypic data for the studied traits. This study demonstrates that a family-based mapping approach can be utilized in rapid detection of QTL associated with heat tolerance in wheat based on linkage and association analyses.  相似文献   

Cross‐sectional survey of health management and prevalence of vector‐borne diseases,endoparasites and ectoparasites in Samoan dogs          下载免费PDF全文

RJ Carslake  KE Hill  K Sjölander  SF Hii  D Prattley  E Acke 《Australian veterinary journal》2017,95(12):462-468

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Epizootics of sudden death in tammar wallabies (Macropus eugenii) associated with an orbivirus infection     

KA Rose  PD Kirkland  RJ Davis  D Blumstein  LI Pritchard  KM Newberry  RA Lunt 《Australian veterinary journal》2012,90(12)

Epizootics of sudden death in tammar wallabies (Macropus eugenii) occurred at six research facilities and zoological gardens in New South Wales, Australia, in late 1998 and at one Queensland research facility in March 1999. There were 120 confirmed tammar wallaby deaths during this period; however, population censuses indicated that up to 230 tammar wallabies may have died. The majority of animals died without premonitory signs. A small proportion of wallabies exhibited increased respiratory rate, sat with a lowered head shortly before death or were discovered in lateral recumbency, moribund and with muscle fasciculations. Gross postmortem findings consistently included massive pulmonary congestion, mottled hepatic parenchyma and subcutaneous oedema throughout the hindlimbs and inguinal region. Approximately 30% of the animals examined also had extensive haemorrhage within the fascial planes and skeletal muscle of the hindlimb adductors, inguinal region, ventral thorax, dorsal cervical region and perirenal retroperitoneal area. The tissues of affected animals became autolytic within a short period after death. Bacteriological examination of tissues from 14 animals did not provide any significant findings. Toxicological examination of the gastric and colonic contents of four animals did not reveal evidence of brodifacoume or other rodenticides. Viruses from the Eubenangee serogroup of the Orbivirus genus were isolated from the cerebral cortex of nine, and the myocardium of two, tammar wallabies and the liver and intestine of another tammar wallaby. A similar orbivirus was also isolated from the cerebrospinal fluid of another tammar wallaby that died suddenly. The disease agent appears to be a previously unrecognised orbivirus in the Eubenangee serogroup. This is the first report of epizootics of sudden deaths in tammar wallabies apparently associated with an orbivirus infection.  相似文献   

Foliage re-establishment of <Emphasis Type="Italic">Pinus palustris</Emphasis> Mill. saplings after spring or fall prescribed fire     

Mary Anne S. Sayer  Michael C. Tyree  Dylan N. Dillaway  Brian M. Rudd 《New Forests》2018,49(6):851-869

Repeated fire is key to the viability of longleaf pine (Pinus palustris Mill.) ecosystems, but its acceptance as a management tool may depend on satisfactory longleaf pine growth. This is because longleaf pine establishment often has the dual-purpose of ecosystem restoration and stemwood production. Timely recovery of scorched foliage among longleaf pine seedlings and saplings supports maximum juvenile growth. We identified two means of foliage re-establishment in the growing season after prescribed fire regardless of the season of fire application. New foliage growth after spring or fall fire was correlated with un-scorched foliage biomass and the presence of lateral branches. After prescribed fire in spring, foliage biomass recovery also appeared to benefit from the mobilization of starch. The high carbon demand of foliage recovery after fall prescribed fire was associated with interruption of seasonal starch accumulation in the stem and taproot. The implication of low starch accumulation in stem and taproot tissues during the growing season after fall prescribed fire is unknown and warrants further investigation. Our results demonstrate a positive influence of residual foliage, lateral branches, and stored starch on timely foliage recovery of young longleaf pines after fire. Together with knowledge of longleaf pine development and fuel and climate conditions at the time of prescribed fire, this information will aid prescribed fire practitioners charged with maintaining longleaf pine stands of high vigor.  相似文献   

Early molecular signatures of responses of wheat to Zymoseptoria tritici in compatible and incompatible interactions          下载免费PDF全文

E. S. Orton  J. J. Rudd  J. K. M. Brown 《Plant pathology》2017,66(3):450-459

Zymoseptoria tritici, the causal agent of septoria tritici blotch, a serious foliar disease of wheat, is a necrotrophic pathogen that undergoes a long latent period. Emergence of insensitivity to fungicides, and pesticide reduction policies, mean there is a pressing need to understand septoria and control it through greater varietal resistance. Stb6 and Stb15, the most common qualitative resistance genes in modern wheat cultivars, determine specific resistance to avirulent fungal genotypes following a gene‐for‐gene relationship. This study investigated compatible and incompatible interactions of wheat with Z. tritici using eight combinations of cultivars and isolates, with the aim of identifying molecular responses that could be used as markers for disease resistance during the early, symptomless phase of colonization. The accumulation of TaMPK3 was estimated using western blotting, and the expression of genes implicated in gene‐for‐gene interactions of plants with a wide range of other pathogens was measured by qRT‐PCR during the presymptomatic stages of infection. Production of TaMPK3 and expression of most of the genes responded to inoculation with Z. tritici but varied considerably between experimental replicates. However, there was no significant difference between compatible and incompatible interactions in any of the responses tested. These results demonstrate that the molecular biology of the gene‐for‐gene interaction between wheat and Zymoseptoria is unlike that in many other plant diseases, indicate that environmental conditions may strongly influence early responses of wheat to infection by Z. tritici, and emphasize the importance of including both compatible and incompatible interactions when investigating the biology of this complex pathosystem.  相似文献