Thermal Structure and Major Ion Composition of the Venus Ionosphere: First RPA Results from Venus Orbiter     

Knudsen WC  Spenner K  Whitten RC  Spreiter JR  Miller KL  Novak V 《Science (New York, N.Y.)》1979,203(4382):757-763

Thermal plasma quantities measured by, the retarding potential analyzer (RPA) are, together with companion Pioneer Venus measurements, the first in situ measurements of the Venus ionosphere. High ionospheric ion and electron temperatures imply significant solar wind heating of the ionosphere. Comparison of the measured altitude profiles of the dominant ions with an initial modlel indicates that the ionosphere is close to diffusive equilibrium. The ionopause height was observed to vary from 400 to 1000 kilometers in early orbits. The ionospheric particle pressure at the ionopause is apparently balanced at a solar zenith angle of about 70 degrees by the magnetic field pressure with little contribution from energetic solar wind particles. The measured ratio of ionospheric scale height to ionopause radius is consistent with that inferred from previously measured bow shock positions.  相似文献   

How does research address the design of innovative agricultural production systems at the farm level? A review   总被引：1，自引：0，他引：1  

P.-Y. Le Gal  P. Dugué  G. Faure  S. Novak 《Agricultural Systems》2011,104(9):714-728

In trying to respond to societal demands for sustainable development, farming systems worldwide face a range of environmental, technical and economic challenges. These challenges call for renewed methodologies that can be used to support farmers in designing innovative agricultural production systems at the farm level. This paper aims to analyze the various methods described in scientific literature. The review is based on the analysis of 80 reference papers published in international scientific journals between 1999 and 2010. We focused in particular on the purpose of the research, which fell into two broad categories: “design” and “design support”. We also examined the use of models to represent production systems and to evaluate ex-ante the impact of innovations on these systems’ functioning and performance. In so doing, we developed a classification system to organize the studies into five sub-categories according to the type of methodology followed, namely: prototyping and design modelling for design orientated studies; participation, support modelling and advisory for design-support orientated studies. We found that very few studies attempt to address the three main components of an innovation process in agricultural production systems (biotechnical processes, farm management, and advisory services) within a single research framework. We therefore developed such a framework by connecting the design and design support orientations together with biotechnical research and conducting integrated research both at farm and advisory service levels.  相似文献   

Use of irradiated pollen as mentor pollen to induce self-fertilization of two self-incompatible Upper Amazon cacao clones     

Y. Adu-Ampomah  F. J. Novak  G. Y. P. Klu  T. V. O. Lamptey 《Euphytica》1990,51(3):219-225

Summary Two self-incompatible Upper Amazon cacao clones, T85/799 and T79/501, were pollinated with compatible Amelonado pollen subjected to varying doses of gamma irradiation (10–100 Gy). The proportion of flat non-viable beans to fully formed, viable beans in the pods increased with an increase in dosage of gamma rays. At 60 Gy all the beans produced were flat and non-viable, beyond this dosage fruit set was zero. Pollinating the self-incompatible cacao clones with a 1 : 1 mixture of compatible mentor pollen irradiated at 60 Gy and normal self pollen produced a mixture of flat, non-viable beans and fully-formed viable beans. Similar experiments using irradiated pollen with a marker gene suggested that the fully-formed viable beans resulted from selfing. Increasing the proportion of the radiation-treated compatible pollen in the mixture increased the number of fully-formed beans. However, when compatible pollen which had been treated either at 80 Gy or with temperatures of 35° C, 40° C and 45° C for periods of five, ten and fifteen minutes in factorial combination were mixed with self pollen, no successful pollinations were achieved. Pollen viability tests indicated that, whilst pollen treated at 60 Gy were about 50% viable, those treated at either 80 Gy or with temperatures of 35–45° C were mostly not viable. This suggests that, to overcome the incompatibility in cacao, the tubes of the mentor pollen grains used should at least grow into the style. The possible causes for overcoming the self-incompatibility in cacao are discussed.  相似文献   

Development of a hybrid variety system in marjoram (Origanum majorana L.)     

J. Langbehn  F. Pank  J. Novak  W.D. Blüthner  Ch. Franz  W. Junghanns  C. Vender 《Euphytica》2001,118(1):83-90

20 accessions of marjoram (Origanum majorana L.)were characterized in two field experiments in Quedlinburg, Germany in 1997. The variation was assessed both on single plants as a base for the development of pollinator inbred lines of a prospective hybrid variety system and also on plots on a larger scale. The characterization comprised yield of leaf-flower fraction, content of essential oil and its proportion of cis-sabinene hydrate. The anther status of the regrowth after the herb harvest was used as an indicator of male fertility. The investigations revealed a high variability between and within accessions. The correlation of some traits is discussed as a clue to indirect selection. The yield rises with increasing bush diameter of the single plants and with longer vegetation periods caused by late flowering. Relations between the essential oil content and the duration of the vegetation period were not consistent and could be caused by the environment. There were no relations between the anther status and agronomical or physiological traits. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Removal of aldrin, heptachlor epoxide, and endrin from potatoes during processing     

J M Solar  J A Liuzzo  A F Novak 《Journal of agricultural and food chemistry》1971,19(5):1008-1010

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Mycotic bronchopneumonia in cattle     

V T Kotov  D D Novak  A M Borisov 《Veterinariia》1969,46(2):55-57

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Double Strand Breaks and Cell-Cycle Arrest Induced by the Cyanobacterial Toxin Cylindrospermopsin in HepG2 Cells     

Alja ?traser  Metka Filipi?  Matja? Novak  Bojana ?egura 《Marine drugs》2013,11(8):3077-3090

The newly emerging cyanobacterial cytotoxin cylindrospermopsin (CYN) is increasingly found in surface freshwaters, worldwide. It poses a potential threat to humans after chronic exposure as it was shown to be genotoxic in a range of test systems and is potentially carcinogenic. However, the mechanisms of CYN toxicity and genotoxicity are not well understood. In the present study CYN induced formation of DNA double strand breaks (DSBs), after prolonged exposure (72 h), in human hepatoma cells, HepG2. CYN (0.1–0.5 µg/mL, 24–96 h) induced morphological changes and reduced cell viability in a dose and time dependent manner. No significant increase in lactate dehydrogenase (LDH) leakage could be observed after CYN exposure, indicating that the reduction in cell number was due to decreased cell proliferation and not due to cytotoxicity. This was confirmed by imunocytochemical analysis of the cell-proliferation marker Ki67. Analysis of the cell-cycle using flow-cytometry showed that CYN has an impact on the cell cycle, indicating G0/G1 arrest after 24 h and S-phase arrest after longer exposure (72 and 96 h). Our results provide new evidence that CYN is a direct acting genotoxin, causing DSBs, and these facts need to be considered in the human health risk assessment.  相似文献   

Effect of supplementation with an electrolyte containing a Bacillus-based direct-fed microbial on immune development in dairy calves     

Novak KN  Davis E  Wehnes CA  Shields DR  Coalson JA  Smith AH  Rehberger TG 《Research in veterinary science》2012,92(3):427-434

Immune characteristics in 65 calves were evaluated in response to a Bacillus-based direct-fed microbial (DFM) provided in electrolyte scour treatment. Blood samples were analyzed for cell surface markers and α(1)-acid glycoprotein (AGP) concentration. AGP increased in scouring calves given electrolyte containing Bacillus at day 7 post-placement compared to scouring calves administered electrolyte alone and non-scouring calves, enhancing the inflammatory response for pathogen clearance. The Bacillus promotes T cell subsets including greater proportions of activated, mature cells (CD8(-)CD25(+), CD8(-)CD45RO(+), CD8(-)TCR1(+)) in calves given electrolyte containing Bacillus than scouring calves administered electrolyte alone and non-scouring calves. Also, the Bacillus may be alleviating inflammation at day 3 post-placement as the proportion of monocytes and granulocytes lacking L-selectin (CD172a(+)CD62L(-)) was greater in scouring calves given electrolyte compared to the other groups. Electrolyte containing Bacillus administered at the onset of scours influences components of innate and adaptive immune development during and following the scouring event.  相似文献   

The Banfield Education Program     

Lewis HB  Novak W 《Journal of veterinary medical education》2003,30(1):33-40

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Comparison of prophylactic or therapeutic dietary administration of capsaicin for reduction of Salmonella in broiler chickens     

Orndorff BW  Novak CL  Pierson FW  Caldwell DJ  McElroy AP 《Avian diseases》2005,49(4):527-533

In three experiments the effects of prophylactic or therapeutic dietary inclusion of capsaicin, the pungent component of peppers, were evaluated as a nonantibiotic alternative for reduction of Salmonella in broiler chickens through culture and morphologic assessment of cecal tissue. Expt. 1 evaluated the effects of 0 or 10 ppm purified capsaicin (CAP) in the starter phase (days 1-16) on chicks challenged with Salmonella Enteritidis (SE) on day of age. Therapeutic inclusion of 10 ppm purified CAP increased (P < 0.05) liver/spleen (L/S) and ceca positive results for SE. In Expt. 2, capsaicin oleoresin (CO) was included in the finisher diet (days 30-37) at 0, 5, or 20 ppm with SE challenge on day 31. Inclusion of 5 ppm CO increased ceca positive results for SE, and a linear decrease in cecal lamina propria thickness of SE-challenged birds was observed with increased CO concentration in the diet. Expt. 3 evaluated prophylactic CO treatment at 0, 5, or 20 ppm in starter, grower, and finisher diets for resistance to SE or Salmonella Typhimurium (ST) challenge on day 14 or 29. With challenge on day 14, 5 and 20 ppm prophylactic CO feeding reduced ceca SE positive results by 37% and 26%, respectively, and ST culture rate was reduced similarly with 5 ppm CO. Lamina propria thickness of the ceca increased with 5 ppm CO feeding in SE-challenged birds, whereas a decrease was observed in nonchallenged birds fed 5 ppm CO. Challenge on day 29 of birds fed 20 ppm CO resulted in reduced L/S positive results for SE. Lamina propria thickness decreased with 5 ppm CO and SE or ST challenge compared with nonchallenged birds fed 5 ppm. An increase was observed in ST- or SE-challenged birds fed 20 ppm CO compared with nonchallenged birds fed 20 ppm CO. No differences were observed in mast cell number in either Expt. 2 or 3. These data provide evidence that prophylactic or therapeutic dietary capsaisin differentially affects broiler susceptibility to Salmonella.  相似文献