Alpha-particle activity of apollo 11 samples     

Richardson KA  McCkay DS  Greenwood WR  Foss TH 《Science (New York, N.Y.)》1970,167(3918):516-517

Nine polishled thin sectionis have been exposed to nulclear track plates, three have been counted by alplia-particle spectrometry, and one has been examined by electron mocroprobe. Interpretation of the results is in a preliminary stage. Alpha track distribiutioni in the autoradiograph of a breccia forms a network that appears related to the rims of accretionary lapilli comiiposinig the breccia. Thorium in a coarse-grained crystalline rock is concenitrated in micron-sized, zirconium-rich crystals. Alplia count rates agree with what would be predicted from previously reported thorium and uranium contents of the same rocks, suggesting secular equilibriunm for the thorium and uranium decay series.  相似文献   

Morphology and related chemistry of small lunar particles from tranquillity base     

McKay DS  Greenwood WR  Morrison DA 《Science (New York, N.Y.)》1970,167(3918):654-656

Glass spherules show multiple high-velocity impact craters and are coated with small particles including glass, plagioclase, clinopyroxene, ilmenite, olivine, chromite, rock fragments, and frozen droplets of iron, nickel-iron, and troilite. These spherules passed through an impact cloud of hot fragmental material, condensing iron-rich vapor and high-velocity projectiles. Breccia contains concentric, accretionary lapilli units and appears to be a sintered deposit from a hot lunar base surge generated by impact.  相似文献   

Malaria--a shadow over Africa     

Miller LH  Greenwood B 《Science (New York, N.Y.)》2002,298(5591):121-122

Reduction in severe disease and death from falciparum malaria in Africa requires new, more effective and inexpensive public health measures. The completed genomes of Plasmodium falciparum and its vector Anopheles gambiae represent a big step toward the discovery of these needed tools.  相似文献   

Comparative losses of British butterflies, birds, and plants and the global extinction crisis     

Thomas JA  Telfer MG  Roy DB  Preston CD  Greenwood JJ  Asher J  Fox R  Clarke RT  Lawton JH 《Science (New York, N.Y.)》2004,303(5665):1879-1881

There is growing concern about increased population, regional, and global extinctions of species. A key question is whether extinction rates for one group of organisms are representative of other taxa. We present a comparison at the national scale of population and regional extinctions of birds, butterflies, and vascular plants from Britain in recent decades. Butterflies experienced the greatest net losses, disappearing on average from 13% of their previously occupied 10-kilometer squares. If insects elsewhere in the world are similarly sensitive, the known global extinction rates of vertebrate and plant species have an unrecorded parallel among the invertebrates, strengthening the hypothesis that the natural world is experiencing the sixth major extinction event in its history.  相似文献   

Continuous infusion of propofol in dogs premedicated with methotrimeprazine   总被引：1，自引：0，他引：1  

Antonio JA Aguiar p  hd Stelio PL Luna p  hd Valéria NLS Oliva p  hd  Flávia R Eugênio MSc  Gladys B Castro p  hd 《Veterinary anaesthesia and analgesia》2001,28(4):220-224

Objective To evaluate the cardiopulmonary and clinical effects of three different infusion rates of propofol in dogs premedicated with methotrimeprazine. Study design Randomized experimental trial. Animals Ten healthy adult mixed‐breed male and female dogs, weighing from 14 to 20 kg. Methods Dogs were premedicated with methotrimeprazine [1 mg kg^?1 intravenously (IV)] followed by induction of anesthesia with 4.5 mg kg^?1 of propofol IV and maintenance with propofol for 60 minutes as follows: T1, 0.2 mg kg^?1 minute^?1; T2, 0.3 mg kg^?1minute^?1; and T3, 0.4 mg kg^?1minute^?1. Heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP), end‐tidal CO₂ (P_ETCO₂), arterial hemoglobin O₂ saturation, arterial blood gases, and pedal and cutaneous reflexes were measured before and 5, 10, 20, 30, 45 and 60 minutes after the beginning of the propofol infusion. Statistical analysis was performed using an anova . Results Heart rate increased during anesthesia in all cases and arterial blood pressure decreased only in dogs in the T3 category. Respiratory depression was proportional to the infusion rate of propofol. Muscle relaxation was satisfactory, but analgesia was inadequate in the three treatments. Conclusions The infusion of 0.2–0.4 mg kg^?1 minute^?1 of propofol produced a dose‐dependent respiratory depression. The presence of a pedal withdrawal reflex and marked cardiovascular responses to this noxious stimulus suggests that anesthesia may not be of sufficient depth for surgery to be carried out. Clinical relevance Although several studies have been performed using propofol in animals, few studies have investigated the cardiopulmonary and analgesic effects with different doses. The determination of an adequate propofol infusion rate is necessary for the routine use of this intravenous anesthetic for the maintenance of anesthesia during major surgical procedures in dogs.  相似文献   

Apoptosis in regressing follicles from Solea solea and Gadus morhua     

P.R. Witthames  E. Andersson  L.N. Greenwood  B. Lyons  M. Fonn  O.S. Kjesbu 《Fish physiology and biochemistry》2003,28(1-4):377-378

Apoptosis in vitellogenic, atretic and post ovulatory follicles was studied in Solea solea and Gadus morhua by either measuring 180–200 bp oligonucleotides or by TUNEL in relation to each follicle type found in histological section. Specifically stained apoptotic nuclei were only present in the granulosa layer of recently produced cod post ovulatory follicles and 180–200 bp oligonucleotides were only found in spent sole ovaries.  相似文献   

Current attitudes regarding the use of perioperative analgesics in dogs and cats by Brazilian veterinarians     

Sílvia ERS Lorena  Stelio PL Luna  B Duncan X Lascelles  José E Corrente 《Veterinary anaesthesia and analgesia》2014,41(1):82-89

  相似文献   

Lunar metallic particle ("mini-moon"): an interpretation     

McKay DS  Carter JL  Greenwood WR 《Science (New York, N.Y.)》1971,171(3970):479-480

A troilite-rich nickel-iron particle ("mini-moon") recovered from the moon may be a mound detached from a sphere of silicate glass. Erosion and pitting of the particle may have been caused by passage through a cloud of hot gas and particulate matter formed by meteorite impact on the lunar surface. This explanation is in contrast to the theory that the particle was meteoritically derived molten material that was furrowed during solidification after lunar impact, subsequently pitted by high-velocity particles, and then abraded and polished by drifting dust while on the lunar surface.  相似文献   

Small ruminant lentivirus genetic subgroups associate with sheep TMEM154 genotypes     

Lucia H Sider  Michael P Heaton  Carol G Chitko-McKown  Greg P Harhay  Timothy PL Smith  Kreg A Leymaster  William W Laegreid  Michael L Clawson 《Veterinary research》2013,44(1):64

Small ruminant lentiviruses (SRLVs) are prevalent in North American sheep and a major cause of production losses for the U.S. sheep industry. Sheep susceptibility to SRLV infection is influenced by genetic variation within the ovine transmembrane 154 gene (TMEM154). Animals with either of two distinct TMEM154 haplotypes that both encode glutamate at position 35 of the protein (E35) are at greater risk of SRLV infection than those homozygous with a lysine (K35) haplotype. Prior to this study, it was unknown if TMEM154 associations with infection are influenced by SRLV genetic subgroups. Accordingly, our goals were to characterize SRLVs naturally infecting sheep from a diverse U.S. Midwestern flock and test them for associations with TMEM154 E35K genotypes. Two regions of the SRLV genome were targeted for proviral amplification, cloning, sequence analysis, and association testing with TMEM154 E35K genotypes: gag and the transmembrane region of env. Independent analyses of gag and env sequences showed that they clustered in two subgroups (1 and 2), they were distinct from SRLV subtypes originating from Europe, and that subgroup 1 associated with hemizygous and homozygous TMEM154 K35 genotypes and subgroup 2 with hemi- and homozygous E35 genotypes (gag p < 0.001, env p = 0.01). These results indicate that SRLVs in the U.S. have adapted to infect sheep with specific TMEM154 E35K genotypes. Consequently, both host and SRLV genotypes affect the relative risk of SRLV infection in sheep.  相似文献   

A survey of the prevalence of emerging macrocyclic lactone resistance and of benzimidazole resistance in sheep nematodes in the lower North Island of New Zealand     

PL Hughes  PB McKenna  AF Dowling 《New Zealand veterinary journal》2013,61(1):87-90

AIM: To investigate the occurrence of emerging macrocyclic lactone (ML) resistance and of resistance to benzimidazole anthelmintics on a number of sheep farms in the North Island of New Zealand.

METHODS: On commercial sheep farms (n=30) in the Taihape district in the North Island of New Zealand, 30 animals were randomly allocated to one of two equal-sized groups and treated with either half of the recommended dose rate of ivermectin (half of 0.2 mg/kg), or with the full recommended dose rate of oxfendazole (4.5 mg/kg). The ivermectin treatment only was used on a further six properties. Faecal egg counts, accompanied by pooled larval cultures, were conducted on all samples at the time of treatment and 7–10 days later.

RESULTS: Resistance, as indicated by a <95% faecal egg count reduction (FECR) in both instances, was found to oxfendazole on 13/30 (43%) farms and to a half dose of ivermectin on 12/36 (33%) properties. For oxfendazole, such resistance was found to involve all six nematode genera whereas for ivermectin it was almost entirely restricted to Ostertagia and Cooperia infections.

CONCLUSIONS: These results indicate that emerging ML resistance may be more common on sheep farms in New Zealand than is generally realised. They also suggest that the half-dose ivermectin faecal egg count reduction test (FECRT) may offer some very practical benefits for parasite control by providing early warning of developing resistance to ML drenches and by signalling the possible imminent failure of these at their therapeutic dose rates. The sensitivity and reliability of this procedure may be further enhanced by the inclusion of larval cultures.  相似文献