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81.
82.
A 17-year-old female blue and gold macaw ( Ara ararauna ) presented for evaluation of a discreet, conjunctival mass of the OD. No other abnormalities were found on ophthalmic or physical examination. A heterophilic leukocytosis was present on the complete blood count, and elevated aspartate aminotransferase activity, creatinine kinase activity and cholesterol were present on the plasma biochemistry panel. Surgical removal of the mass was complete and no recurrence has occurred by six months after excision. Reduction of dietary fats was recommended to reduce serum cholesterol levels and reduce the likelihood of future occurrence of xanthomas in this bird.  相似文献   
83.
Progesterone plays an important role in maintenance of pregnancy. It is hypothesized that insufficient progesterone early in pregnancy may result in embryonic loss, and that supplemental progesterone would decrease pregnancy loss in dairy cows. In Experiment 1, 84 cows and 16 heifers from a single dairy operation were selected randomly. Within each age category, controlled internal drug release (CIDR) devices were inserted into the vagina of every other female on Day 4 post-insemination and removed on Day 18 post-insemination. Transrectal ultrasonography was performed to determine pregnancy at 4 time periods [days 30 to 37 (week 5), days 44 to 51 (week 7), days 58 to 65 (week 9), and days 86 to 93 (week 13)]. Progesterone supplementation had no effect on pregnancy rate. In Experiment 2, there were no differences in progesterone concentrations between cows that did and did not receive a CIDR. Further, cows receiving CIDR devices did not have an increase in circulating progesterone concentrations 30 min or 1 h after CIDR insertion. It appears that progesterone supplementation does not increase circulating levels of progesterone in the early pregnant lactating dairy cow. Alterative methods to influence progesterone concentrations and/or early embryonic loss need to be investigated.  相似文献   
84.
Wood quality attributes were examined in six stands of slash pine (Pinus elliottii Engelm. var. elliottii) and loblolly pine (P. taeda L.) in the lower Coastal Plain of Georgia and Florida. Several plots comprised each stand, and each plot was divided so that it received three fertilizer treatments: a control treatment with herbaceous weed control at planting and brush control at mid-rotation only (control); 45 kg ha−1 N + 56 kg ha−1 P + herbaceous weed control at planting and 224 kg ha−1 N + 45 kg ha−1 P + brush control at mid-rotation (fertilizer with N at planting); and 56 kg ha−1 P + herbaceous weed control at planting and 224 kg ha−1 N + 45 kg ha−1 P + brush control at mid-rotation (fertilizer without N at planting). Ring width, ring earlywood specific gravity (SG), ring latewood SG, whole ring SG, and ring percent latewood were measured on each of seven trees. Of these measurements, this study focused mainly on the properties related to SG. Examination of the rings showed that latewood SG was significantly lower in trees treated with fertilizers with and without N at planting in the two to three years following fertilization, but that latewood SG gradually returned to a level similar to the control. Fertilizer without N at planting may also have had a brief negative effect on earlywood SG following mid-rotation fertilization, but it was not as clear or lasting as the effect on latewood SG. Additionally, although slash and loblolly pine appear to differ in the developmental patterns of these SG properties, there were no significant differences in how these patterns interacted with treatment. This study demonstrated that fertilization treatments have similar short-term effects on the SG of slash and loblolly pines, particularly in latewood, but the trees will return to a SG pattern consistent with unfertilized trees within two or three years.  相似文献   
85.
To improve sorghum grain protein nutritional quality, improved sorghum lines were transformed to suppress the synthesis of different kafirin sub-classes, or backcrossed into transgenic lines with improved protein quality. Co-suppression of the alpha-, gamma- and delta-kafirin sub-classes and removal of the tannin trait resulted in transgenic sorghum lines with high cooked protein digestibility (±80%), improved Amino Acid Score (0.8) and Protein Digestibility Corrected Amino Acid Score (0.7) compared to the non-transgenic null controls (±50%, 0.4 and 0.2, respectively). These high protein quality lines had a floury endosperm. They also had modified protein body structure, where the protein bodies were irregular shaped with few to numerous invaginations and were less densely packed, with a dense protein matrix visible around the protein bodies. When fewer sub-classes were suppressed, i.e. gamma 1 and delta 2, the endosperm was corneous with normal protein body structure but the improvement in cooked protein digestibility appeared to be less. Apparently, co-suppression of several kafirin sub-classes is required to obtain high protein nutritional quality sorghum lines, but this seems to result in floury-type grain endosperm texture.  相似文献   
86.
87.
Several remote observations have indicated that water ice may be presented in permanently shadowed craters of the Moon. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed to provide direct evidence. On 9 October 2009, a spent Centaur rocket struck the persistently shadowed region within the lunar south pole crater Cabeus, ejecting debris, dust, and vapor. This material was observed by a second "shepherding" spacecraft, which carried nine instruments, including cameras, spectrometers, and a radiometer. Near-infrared absorbance attributed to water vapor and ice and ultraviolet emissions attributable to hydroxyl radicals support the presence of water in the debris. The maximum total water vapor and water ice within the instrument field of view was 155 ± 12 kilograms. Given the estimated total excavated mass of regolith that reached sunlight, and hence was observable, the concentration of water ice in the regolith at the LCROSS impact site is estimated to be 5.6 ± 2.9% by mass. In addition to water, spectral bands of a number of other volatile compounds were observed, including light hydrocarbons, sulfur-bearing species, and carbon dioxide.  相似文献   
88.
Successful management or restoration of southern floodplain forest ecosystems requires an understanding of how subtle changes in environmental conditions such as site hydroperiod affect species suitability as well as the importance of recruitment limitation. In this research, we examined the effects of elevation, modeled flood regime, soil conditions and forest proximity on early, post-logging succession in clearcuts on the Congaree River floodplain near Columbia, South Carolina. Analyses of community composition clearly demonstrated that regeneration was structured along environmental gradients associated with site hydroperiod, with obligate wetland species dominating sites with the lowest elevations and deepest projected flood inundation depths. The effects of soil characteristics on site composition were in some cases inter-correlated with site hydroperiod, reflecting the influence of flood regime on soil drainage, aeration, and soil redox potential. In other cases, though, site composition was distinguished along a second, but equally important, orthogonal axis that was more reflective of the effects of geomorphic history on edaphic conditions. There was no evidence that fine-scale dispersal limitation affected succession, in part because of the effects of resprouting, but it is possible that past human activities have altered landscape-scale patterns of commercially valuable species such that seed and sprout sources for advance regeneration may have been absent at the time of the most recent clearcutting. Our examination of regeneration patterns, processes and controls clarified the relationships between current conditions and community composition, but, because patterns of elevation, flooding and soil characteristics across a floodplain have their roots in geomorphic processes, they are also ultimately a reflection of past hydrogeomorphic events.  相似文献   
89.
Global Assessment of Human-Induced Soil Degradation   总被引:1,自引:0,他引:1  

Soil is a valuable natural resource that in the short - term is nonrenewable and is difficult to reclaim when degraded. The use of soils on a sustainable basis requires that their capability to withstand the demands upon them is not exceeded. Those people concerned with conservation should be aware of the vital importance of soil for maintaining food supplies for an increasing world population. Increasing demands place a greater strain upon the soil. If the demands become too great, the soil becomes degraded. As soil is the basis of all terrestrial ecosystems, a degraded soil means lower fertility, reduced biodiversity, and human poverty. To provide basic information on soil degradation worldwide, a survey of soil loss through erosion, physical deterioration, and chemical pollution was made. Digital databases are not available to hold information necessary to monitor and combat soil degrada tion at global and national scales. Soil degradation is recognized as a serious and widespread problem, so in September 1987 the International Soil Reference and Information Centre was commissioned to make a survey for a map at a scale of 1:10,000,000 entitled "Global Assessment of Human - Induced Soil Degradation" (GLASOD). Until it was published in 1990, there was no uniformly collected body of information on soil degradation worldwide. The GLASOD survey provides basic data on the world distribution and intensity of erosional, chemical, and physical types of degradation. The original purpose of GLASOD was to provide factual information, to replace sweeping statements about soil and land degradation, and to raise awareness of policy makers and governments for the continuing need for soil conservation. The GLASOD survey also enables comparisons to be drawn between degraded soils of different continents, and the methodology used can be a basis upon which plans for restoration of degraded lands can be based.  相似文献   
90.
Improving our knowledge of pre-anthropogenic landscapes is vital for understanding landscape-scale heterogeneity and for setting goals and objectives for ecological restoration. This is especially important in highly modified landscapes that contain few remnants of pre-impact ecosystems. This study aims to develop new methodology to improve understanding of historical vegetation, using the now-degraded inhabited highlands of the Galapagos Islands as a case study. Our multidisciplinary approach innovatively combines data from interviews with residents who were familiar with the vegetation before most degradation occurred with the more traditional sources of historical aerial photography and information from early explorer and scientist reports. We reconstruct historical vegetation across the landscape by mapping it in the year 1960 and discussing this map in the historical context of anthropogenic change. Our results confirm published vegetation types but also define some other types not previously described, and suggest much greater spatial, temporal and structural heterogeneity than commonly understood. This result can be used by Galapagos land managers to better match species assemblages with sites and plan restoration actions that will maximise resilience against the ongoing and future threats of climate change and species invasions. Our methodology can be applied in extensive areas of the world where the majority of anthropogenic disturbance to natural ecosystems has been within the past 60 years.  相似文献   
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