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991.
After mating, mammalian spermatozoa are transported to the lower oviductal isthmus. Spermatozoa are sequestered at the isthmus by attaching and interacting with oviductal epithelial cells, hence forming a sperm reservoir. In several mammalian species, specific carbohydrates mediate sperm-oviductal epithelial cell binding. A quantitative in vitro free cell bioassay was developed to investigate the involvement of carbohydrate recognition in pig sperm-oviductal epithelial cell interactions. This assay was validated. The sensitivity of the assay was such that it was possible to discriminate between different sperm concentrations and sperm-oviductal epithelial cell co-incubation periods, spermatozoa with damaged plasma membranes and epithelial cells of non-reproductive origin. Optimal conditions were used to incubate spermatozoa and oviductal epithelial cells in the presence of six hexose sugars at concentrations of 0, 2, 10 and 50 mmol l(-1). A significant (P < or = 0.05) reduction in the binding of spermatozoa to the oviductal epithelium was detected with 2, 10 and 50 mmol maltose l(-1), 50 mmol lactose l(-1) and 50 mmol mannose l(-1). These findings support the hypothesis that attachment of pig spermatozoa to oviductal epithelium before fertilization is mediated by carbohydrate recognition.  相似文献   
992.
Domestic coal combustion can emit various air pollutants. In the present study, we measured emissions of particulate matter (PM) and gaseous pollutants from burning a specially formulated honeycomb coal (H-coal) and a coal cake (C-coal). Flue gas samples for PM2.5, PM coarse (PM2.5-10), and TSP were collected isokinetically using a cascade impactor; PM mass concentrations were determined gravimetrically. Concentrations of SO2, NOx, and ionic Cr(VI) in PM were analyzed using spectrometric methods. Fluoride concentrations were measured using a specific ion electrode method. PM elemental components were analyzed using an X-ray fluorescence technique. Total (gas and particle phase) benzo[a]pyrene (BaP) concentration was determined using an HPLC/fluorescence method. Elemental and organic carbon contents of PM were analyzed using a thermal/optical reflectance technique. The compositional and structural differences between the H-coal and C-coal resulted in different emission characteristics. In generating 1 MJ of delivered energy, the H-coal resulted in a significant reduction in emissions of SO2 (by 68%), NOx (by 47%), and TSP (by 56%) as compared to the C-coal, whereas the emissions of PM2.5 and total BaP from the H-coal combustion were 2-3-fold higher, indicating that improvements are needed to further reduce emissions of these pollutants in developing future honeycomb coals. Although the H-coal and the C-coal had similar emission factors for gas-phase fluoride, the H-coal had a particle-phase fluoride emission factor that was only half that of the C-coal. The H-coal had lower energy-based emissions of all the measured toxic elements in TSP but higher emissions of Cd and Ni in PM2.5.  相似文献   
993.
A prototype walk-through fly vacuum system, designed to remove horn flies Haematobia irritans (L.) (Diptera: Muscidae) from cattle, was developed and tested for efficacy. The study was conducted during 4 fly seasons over 17 consecutive weeks each year within the months of May through September at 1 dairy research herd in the coastal plain of North Carolina. Additional data on horn flies, as well as face flies (Musca autumnalis) and stable flies (Stomoxys calcitrans), were collected during 1 yr from 7 commercial pasture-based and organic dairy farms in the piedmont region of North Carolina. The number of flies observed on animals in the pasture was compared with the number of flies collected in the trap. Studies were initiated after horn fly densities had met or exceeded a threshold of 200 flies per animal. The vacuum trap removed between 1.3 and 2.5 million flies annually from the research station cattle. Most fly removal occurred during the first few weeks of operation and maintained densities below threshold thereafter. Cattle using the fly trap at the research farm had only about 28% the number of horn flies as untreated cattle, and reductions ranged from 67.5 to 74.5% across the 4-yr study. In addition to large numbers of horn flies, traps placed on commercial dairies during 1 yr collected stable flies, face flies, and house flies, all species with differing behavior and larger in size than horn flies. The estimated cost of running the trap is $72 per season at commercial rates of $0.12 per hour and an expected 4 h of daily operation during the time of milking. Use of a vacuum system as described herein has potential as a cost-effective method in reducing populations of parasitic flies in pasture-based dairy production systems without the use of insecticides.  相似文献   
994.
Sensory properties and rate of meltdown of nonfat (0% fat) and low-fat (2% fat) vanilla ice creams processed either by conventional valve homogenization or microfluidization of their mixes were compared with each other and to ice cream (10% fat) processed by conventional valve homogenization. Mixes for frozen dairy desserts containing 0, 2, and 10% fat were manufactured. Some of the nonfat and low-fat ice cream mixes were processed by microfluidization at 50, 100, 150, and 200 MPa, and the remaining nonfat and low-fat ice cream mixes and all of the ice cream mix were processed by conventional valve homogenization at 13.8 MPa, first stage, and 3.4 MPa, second stage. The finished frozen and hardened products were evaluated at d 1 and 45 for meltdown rate and for flavor and body and texture by preference testing. Nonfat and low-fat ice creams that usually had a slower meltdown were produced when processing their mixes by microfluidization instead of by conventional valve homogenization. Sensory scores for the ice cream were significantly higher than sensory scores for the nonfat and low-fat ice creams, but the sensory scores for the conventional valve homogenized controls for the nonfat ice cream and low-fat ice cream were not significantly different from the sensory scores for the nonfat ice cream and low-fat ice cream processed by microfluidization of the mixes, respectively. Microfluidization produced nonfat and low-fat ice creams that usually had a slower meltdown without affecting sensory properties.  相似文献   
995.
Processes of state-society engagement around urban development issues, termed co-production, have been documented in both the Public Administration and Development Studies fields, but until recently have not attracted much attention in planning. Yet, particularly more recent approaches and cases of co-production from global South contexts do offer the possibility of adding to planning debates in this area, by expanding the context which shapes planning ideas beyond the global North, and perhaps shifting planning theory in the direction of becoming truly international. The paper identifies the important differences which underlie various strands of thinking about co-production, and also between these and planning assumptions in the area of collaborative and communicative planning.  相似文献   
996.
Researchers have hypothesized that words that are highly related semantically are more likely to occur within the same intonational phrase (F. zzaq;, 1988; E. O. Selkirk, 1984). D. Watson and E. Gibson (2004) proposed that semantic closeness can be captured by using the argument/adjunct distinction, such that intonational boundaries are more likely to occur before adjuncts than before arguments. In the current experiment, the authors compared two aspects of argumenthood: semantic relatedness and obligatoriness. In a production study, speakers were more likely to place an intonational phrase boundary between a word and a dependent if the dependent was optional (e.g., after "investigation" in "The reporter's investigation [of the crash] unnerved the officials") than if the dependent was obligatory (e.g., after "investigated" in "The reporter investigated [the crash], and this unnerved the officials"). These data suggest that obligatoriness is a better predictor of intonational boundary placement than semantic closeness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
997.
Recent studies have shown improved NMOSFET transistor hot-carrier lifetime with the inclusion of a low-temperature post-metal anneal in a deuterium ambient. There have been few published results, however, on the optimization of the deuterium anneal or on the effect of further processing on deuterium-annealed samples. This paper reports the first results incorporating deuterium anneals at earlier steps in the process and the stability of the deuterium effect with further wafer processing. We also examine the effects of varying deuterium concentration in the anneal from 10 to 100% and annealing at different temperatures. Finally, the effect of combining a deuterium anneal with nitrided gate oxide is discussed  相似文献   
998.
As a small-cell path-loss prediction model, the COST 231-Walfisch-Ikegami model has been used extensively. It facilitates radio frequency (RF) path-loss predictions in typical suburban and urban environments where the building heights are quasi-uniform. However, it was found that the expression accounting for the diffraction loss from the last rooftop to the street was erroneously obtained. In this paper, we show why the error is present in the COST 231-Walfisch-Ikegami model and how it impacts on path-loss prediction  相似文献   
999.
1000.
Managing the three Levels of Change   总被引:1,自引:0,他引:1  
Change may be introduced into an organization a variety of ways - implementing new technology, employing new people, or in establishing new organizational structures, new policies, or new procedures. Just as change is made up of different components, it comes in varying degrees. A three-level classification of change can help IS managers gain control over the variable components and nature of change.  相似文献   
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