Early central andean metalworking from mina perdida, peru     

RL Burger  RB Gordon 《Science (New York, N.Y.)》1998,282(5391):1108-1111

Copper and gold artifacts in contexts dated to approximately 3120 to 3020 carbon-14 years before the present ( approximately 1410 to 1090 calendar years B.C.) recovered in excavations at Mina Perdida, Lurin Valley, Peru, show that artisans hammered native metals into thin foils, in some cases with intermediate anneals. They gilded copper artifacts by attaching gold foil. The artifacts show that fundamental elements of the Andean metallurgical tradition were developed before the Chavin horizon, and that on the Peruvian coast the working of native copper preceded the production of smelted copper objects.  相似文献   

Magnetic microstructure of magnetotactic bacteria by electron holography     

RE Dunin-Borkowski  MR McCartney  RB Frankel  DA Bazylinski  M Posfai  PR Buseck 《Science (New York, N.Y.)》1998,282(5395):1868-1870

Off-axis electron holography in the transmission electron microscope was used to correlate the physical and magnetic microstructure of magnetite nanocrystals in magnetotactic bacteria. The magnetite crystals were all single magnetic domains, and the magnetization directions of small superparamagnetic crystals were constrained by magnetic interactions with larger crystals in the chains. Shape anisotropy was found to dominate magnetocrystalline anisotropy in elongated crystals. A coercive field between 300 and 450 oersted was determined for one chain.  相似文献   

Estimation of a reliable evapotranspiration model and crop coefficient in red gram ( Cajanus cajan L .) for semi-arid environments in India     

RB Singandhupe  Ranu Rani Sethi  GS Katti 《Archives of Agronomy and Soil Science》2013,59(4):433-445

The study aims to compute the reference evapotranspiration (ETo) by six standard methods such as Penman Monteith, Modified Penman, Hargreaves, Radiation Balance, Blaney Criddle and Pan Evaporation by using the meteorological data of the All India Coordinated Research Project on Water Management at Rahuri, India (long. 74° 18′, lat. 19° 45′). These methods were compared with lysimeter crop evapotranspiration (ETc) by statistical tools. The results revealed that the total lysimeter ETc of red gram in 132 days' growing period (sowing to harvest) was 494?mm and the ETo in the above-mentioned models were 485.2, 486.9, 544.6, 547.6, 563.9 and 485.2?mm, respectively. Out of six models, ETo of Modified Penman and Pan Evaporation methods were very much close to lysimeter ETc, but the coefficient of variation was very high, i.e., 43.05% and 23.91%, respectively. But in the Hargreaves and Blaney Criddle methods, the coefficient of variation was low, i.e., 15.97% and 12.6%, respectively. Besides low coefficient of variation, these two methods require limited meteorological parameters such as minimum and maximum temperature, radiation. For generating these parameters even at regional level, minimum expenditure is involved. The crop coefficient (Kc) estimated by Hargreaves (Kc 0.90) and the Blaney Criddle (0.87) model for the entire growing season was very much close to the Food and Agricultural Organization (FAO) 56 model, and this can be used for estimating the irrigation requirement of red gram.  相似文献   

Nocardiosis in a tui (Prosthemadera novazeelandiae)     

RB Suepaul  MR Alley 《New Zealand veterinary journal》2013,61(1)

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Vertical Flux of Biogenic Carbon in the Ocean: Is There Food Web Control?     

RB Rivkin  L Legendre  D Deibel  JE Tremblay  B Klein  K Crocker  S Roy  N Silverberg  C Lovejoy  F Mesple  N Romero  MR Anderson  P Matthews  C Savenkoff  A Vezina  JC Therriault  J Wesson  C Berube  RG Ingram 《Science (New York, N.Y.)》1996,272(5265):1163-1166

Models of biogenic carbon (BC) flux assume that short herbivorous food chains lead to high export, whereas complex microbial or omnivorous food webs lead to recycling and low export, and that export of BC from the euphotic zone equals new production (NP). In the Gulf of St. Lawrence, particulate organic carbon fluxes were similar during the spring phytoplankton bloom, when herbivory dominated, and during nonbloom conditions, when microbial and omnivorous food webs dominated. In contrast, NP was 1.2 to 161 times greater during the bloom than after it. Thus, neither food web structure nor NP can predict the magnitude or patterns of BC export, particularly on time scales over which the ocean is in nonequilibrium conditions.  相似文献   

Genetics and molecular specificity of sialylation of Histophilus somni lipooligosaccharide (LOS) and the effect of LOS sialylation on Toll-like receptor-4 signaling     

Howard MD  Willis L  Wakarchuk W  St Michael F  Cox A  Horne WT  Hontecillas R  Bassaganya-Riera J  Lorenz E  Inzana TJ 《Veterinary microbiology》2011,153(1-2):163-172

Histophilus somni is an etiologic agent of bovine respiratory and systemic diseases. Most pathogenic strains of H. somni that have been tested (36 of 42) are able to utilize N-acetyl-5-neuraminic acid (Neu5Ac) to sialylate their lipooligosaccharide (LOS). Homologs of all the genes required for transport, metabolism, and regulation of Neu5Ac in Haemophilus influenzae were identified in the sequenced genomes of H. somni. Three open reading frames (ORFs) in H. somni strain 2336 were identified that contained homology to genes required for LOS sialylation in related bacteria. ORF-1 (hssT-I), ORF-2 (hssT-II), and ORF-3 (neuA(Hs)) were predicted to encode for putative proteins with 37% amino acid homology to an α-(2-3)-sialyltransferase in H. influenzae, 43% amino acid homology to an Haemophilus ducreyi sialyltransferase, and 72% amino acid homology to an H. influenzae CMP-Neu5Ac synthetase, respectively. The specific enzyme activity of each ORF was determined using synthetic acceptor substrates. The HssT-I sialyltransferase primarily sialylated N-acetyllactosamine (LacNAc, Gal-β-[1-4]-GlcNAc-R), which is expressed on strain 2336, whereas HssT-II preferentially sialylated lacto-N-biose (LNB, Gal-β-[1-3]-GlcNAc-R), which is expressed on a phase variant of strain 2336: strain 738. Phase variation of the terminal galactose linkage in strain 738 from β-(1-3)-(LNB) to β-(1-4)-(LacNAc) was confirmed using monoclonal antibody reactivity and nuclear magnetic resonance spectroscopy. Sialylated LOS induced significantly less chemokine response from macrophages derived from Toll-like receptor (TLR)-4 knockout mice than from de-sialylated LOS. Furthermore, sialylated LOS induced significantly less NF-κB activity from mouse-derived bone marrow macrophages than de-sialylated LOS. Therefore, sialylation inhibited LOS signaling through TLR-4. In conclusion, H. somni utilizes linkage-specific sialyltransferases to sialylate its LOS to avoid innate host defense mechanisms despite simultaneous epitope phase variation.  相似文献   

Release of protein-bound residues of thiabendazole from liver   总被引：1，自引：0，他引：1  

Horne E  Coyle T  O'Keeffe M  Alvinerie M  Galtier P  Brandon DL 《Journal of agricultural and food chemistry》2003,51(18):5552-5555

Tissue-bound residues of thiabendazole (TBZ), a veterinary anthelmintic and postharvest fungicide, are formed when this compound is incubated with rabbit hepatocytes or administered to mice or pigs. Several pretreatment steps were investigated for removing free TBZ and metabolites prior to the release of bound residues, and three procedures were evaluated for the release of bound residues from solvent-extracted rabbit hepatocytes: incubation under acidic conditions, enzymatic action using cystathionine beta-lyase, and Raney nickel desulfurization. Immunoaffinity chromatography utilizes monoclonal antibodies capable of binding TBZ or its 5-hydroxy metabolite enabled isolation of crossreactive residue fractions. Residues released from incurred pig liver and isolated by immunoaffinity included TBZ, as determined by HPLC with photodiode array detection. The methodology described should facilitate food safety assessments of TBZ.  相似文献   

A cross-sectional study to show Eperythrozoon ovis infection is prevalent in Western Australian sheep farms   总被引：4，自引：0，他引：4  

MJ KABAY  RB RICHARDS  TE ELLIS 《Australian veterinary journal》1991,68(5):170-173

A serological survey and risk factor study was conducted to estimate the prevalence of Eperythrozoon ovis infection in Western Australian weaner sheep, the prevalence of farms with infected sheep, and to identify factors affecting initiation and maintenance of infection on the farm. The study was conducted on 91 farms, purposively chosen from 41 randomly selected regional shires stratified by sheep number and rainfall zones. Twenty sheep were selected systematically from a mixed-sex flock on each farm and tested for serum antibody to E ovis using an enzyme-linked immunosorbent assay. Information on putative risk factors was collected using an interview questionnaire. Antibody to E ovis was detected in 4.5% of sheep on 47% of the farms sampled. The prevalence of E ovis infection in sheep was estimated at the 95% confidence level to be between 3.6 and 5.5%, and the prevalence of farms with infected sheep was estimated to be between 37.5 and 56.5%. Most farms with serological evidence of infection occurred in the Great Southern agricultural region (79.5%), south-east of Perth through to Albany (latitude 32 to 34 degrees S, longitude 116 to 120 degrees E), and in the Northern region (12.8%) surrounding Geraldton (latitude 29 degrees S, longitude 114 degrees E). There were significantly more farms (P less than 0.05) with evidence of infection in the Great Southern region compared to the Central region between Geraldton and Perth, and on farms in the region south compared to north of latitude 32 degrees S. None of the putative risk factors examined in the questionnaire were associated with serological evidence of infection on the farm.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Epidemiology of salmonellosis in the live sheep export industry     

ARE HIGGS  RT NORRIS  RB RICHARDS 《Australian veterinary journal》1993,70(9):330-335

SUMMARY Salmonellosis in sheep was studied on 7 commercial voyages from Australia to the Middle East and in one animal house study. Faecal excretion of salmonellas was not a good indicator of pathological changes in the gastrointestinal tract. The ratio of the proportion of sheep excreting salmonellas to the proportion with histological lesions of salmonellosis ranged from 1:1 to 23:1. Increasing excretion rates in our studies indicated that most sheep would be exposed to infection, although deaths from salmonellosis were not spatially or temporally clustered as would be expected if challenge alone was a sufficient cause. We considered that inappetence predisposed to death from salmonellosis, and that sheep with inappetence were likely to be randomly distributed aboard ship. In the animal house study, histological lesions of salmonellosis were exclusively in inappetent sheep although almost all sheep excreted salmonellas in faeces. Lesions of salmonellosis were found only in sheep that were seriously ill or had died, which suggested that, under the conditions of lot-feeding and sea transport, most sheep with enteric lesions are likely to die. Lesions were not found in feeding controls. Adrenal gland weights, an indicator of stress duration and severity, were used to examine the temporal sequence of events in the development of salmonellosis. Weights were greater in sheep that died of inanition than in controls, suggesting that inappetent sheep were already stressed for that reason. The presence of enteric lesions of salmonellosis was associated with further increases in adrenal gland weights. In a small proportion of cases, septicaemic salmonellosis developed rapidly and without adrenal gland hypertrophy suggesting that the sheep succumbed before the adrenal glands had time to enlarge. We concluded that sheep were predisposed to salmonellosis by inappetence and that stress was involved in lesion development. We considered that the development of enteric lesions of salmonellosis, in the live export system, inevitably led to death.  相似文献   

SPINAL FRACTURE [LUXATION] FIXATION BY VERTEBRAL BODY PLATING, SCREWS, OR WIRE     

R. D. Horne 《Veterinary surgery : VS》1974,3(2):22-23

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