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Little Decline (little + decline)
Selected AbstractsModelling the effects of loss of soil biodiversity on ecosystem functionGLOBAL CHANGE BIOLOGY, Issue 1 2002H. W. Hunt Abstract There are concerns about whether accelerating worldwide loss of biodiversity will adversely affect ecosystem functioning and services such as forage production. Theoretically, the loss of some species or functional groups might be compensated for by changes in abundance of other species or functional groups such that ecosystem processes are unaffected. A simulation model was constructed for carbon and nitrogen transfers among plants and functional groups of microbes and soil fauna. The model was based on extensive information from shortgrass prairie, and employed stabilizing features such as prey refuges and predator switching in the trophic equations. Model parameters were derived either from the literature or were estimated to achieve a good fit between model predictions and data. The model correctly represented (i) the major effects of elevated atmospheric CO2 and plant species on root and shoot biomass, residue pools, microbial biomass and soil inorganic nitrogen, and (ii) the effects on plant growth of manipulating the composition of the microbial and faunal community. The model was evaluated by comparing predictions to data not used in model development. The 15 functional groups of microbes and soil fauna were deleted one at a time and the model was run to steady state. Only six of the 15 deletions led to as much as a 15% change in abundance of a remaining group, and only two deletions (bacteria and saprophytic fungi) led to extinctions of other groups. Functional groups with greater effect on abundance of other groups were those with greater biomass or greater number of consumers, regardless of trophic position. Of the six deletions affecting the abundance of other groups, only three (bacteria, saprophytic fungi, and root-feeding nematodes) caused as much as 10% changes in indices of ecosystem function (nitrogen mineralization and primary production). While the soil fauna as a whole were important for maintenance of plant production, no single faunal group had a significant effect. These results suggest that ecosystems could sustain the loss of some functional groups with little decline in ecosystem services, because of compensatory changes in the abundance of surviving groups. However, this prediction probably depends on the nature of stabilizing mechanisms in the system, and these mechanisms are not fully understood. [source] Changing cancer incidence in Kampala, Uganda, 1991,2006INTERNATIONAL JOURNAL OF CANCER, Issue 5 2010Donald Maxwell Parkin Abstract Incidence rates of different cancers have been calculated for the population of Kyadondo County (Kampala, Uganda) for a 16-year period (1991,2006). This period coincides with continuing social and lifestyle changes and the peak and subsequent wane of the epidemic of HIV-AIDS. There has been an overall increase in the risk of cancer during the period in both sexes, with the incidence rates of cancers of the breast and prostate showing particularly marked increases (4.5% annually). Prostate cancer is now the most common cancer in men. The incidence of cancer of the esophagus, formerly the most common cancer in men and second in frequency in women, has remained relatively constant, whereas the incidence of cancer of the cervix, the most common malignancy in women, continues to increase. Since the early 1990s the incidence of Kaposi sarcoma (KS) in men has declined, and while remaining relatively constant in women, it has been diagnosed at progressively later ages. The rates of pediatric KS have declined by about 1/3rd. The incidence of squamous cell cancers of the conjunctiva has also declined since the mid 1990s. Cancer control in Uganda, as elsewhere in sub-Saharan Africa, involves meeting the challenge of emerging cancers associated with westernization of lifestyles (large bowel, breast and prostate); although the incidence of cancers associated with poverty and infection (liver, cervix, esophagus) shows little decline, the residual burden of the AIDS-associated cancers remains a major burden. [source] Sedimentation of Soils from Three Physiographic Regions of Alabama at Different SalinitiesJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2009Gulnihal Ozbay This study evaluated the rate of sedimentation from water under various salinities, over a time period of 72 h. The particles come from soils that are commonly found in shrimp growing areas of Alabama: Black Belt Prairie, Piedmont Plateau, and Upper Coastal Plain. Different salinity treatments and settling times resulted in significant differences (P, 0.05) in the reduction of turbidity and TSS for each soil type. Solutions containing 2 ppt salinity had a similar rate of turbidity reduction as the solutions with 5, 10, or greater ppt treatments. Concentrations of turbidity and TSS decreased rapidly between 1 and 12 h of sedimentation; very little decline was observed during the time intervals 12,72 h. Higher salinity treatments yielded settling patterns similar to the 2 ppt salinity treatment. After 1 h, turbidity was removed by 65% in the control compared with 85% salinity treated samples. Variations in turbidity and TSS among the three sediments suggest that finer particles, the Piedmont Plateau soils, settled at a slower rate than larger particles. This difference occurs because the percentage of turbidity and TSS removed was significantly higher in mineralized waters compared to freshwater. Therefore, a small amount of salt, 2 ppt, can be used in pond aquaculture treatments to reduce the turbidity and TSS concentrations in shrimp ponds. [source] Plasma Clearance of Exogenous Creatinine, Exo-Iohexol, and Endo-Iohexol in Hyperthyroid Cats before and after Treatment with RadioiodineJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2008I. Van Hoek Background: Glomerular filtration rate (GFR) can be measured by clearance methods of different markers showing discrepancies and different reproducibility in healthy cats. Studies comparing different methods of GFR measurement in hyperthyroid cats have not yet been performed. Hypothesis: Plasma clearance of exogenous creatinine (PECCT), exo-iohexol (PexICT), and endo-iohexol (PenICT) could lead to differences in GFR measurement and the need to use the same clearance method when comparing GFR before and after radioiodine treatment in hyperthyroid cats. Animals: Fifteen client-owned hyperthyroid cats. Methods: GFR was measured 1 day before and 1, 4, 12, and 24 weeks after treatment. Intravenous injection of iohexol was followed immediately by IV injection of creatinine. Plasma creatinine was measured by an enzymatic method. Plasma endo- and exo-iohexol were measured by high-performance liquid chromatography coupled to ultraviolet detection. Results: Globally, the 3 GFR methods resulted in significantly different (P < .001) GFR results. GFR results among the different methods were the same (P= .999) at all time points. All 3 techniques indicated decreasing GFR after 131I treatment. For each GFR technique, a significant decrease in GFR was observed between time point 0 and all other time points. This decrease stabilized 4 weeks after treatment, with very little decline afterward. Conclusion and Clinical Importance: It is mandatory to use the same GFR technique in follow-up studies. GFR testing at 4 weeks posttreatment could allow assessment of the final renal functional loss after treatment in hyperthyroid cats. [source] Fertility transition in Ghana: looking back and looking forwardPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 6 2006Samuel Agyei-Mensah Abstract It is widely accepted that while the fertility transition is underway in sub-Saharan Africa, the pattern of change differs widely in both time and space. This paper examines the case of Ghana, regarded as the vanguard in the West African fertility transition. Based largely on analyses of Demographic and Health Survey data as well as localised studies, significant patterns emerge. One puzzling finding is that the increase in modern contraception usage has not kept pace with the declines in fertility. The paper suggests that this mismatch can be explained either by an increase in induced abortions, reduced exposure to sexual relations (perhaps due to HIV), or misreporting of contraceptive use. The paper also highlights the considerable geographical diversity in the ongoing fertility transition. The Northern region is still in the pre-transition stage, with little decline in fertility to date. In contrast, the pace of decline has been very rapid in the Greater Accra region. The factors underlying these patterns and the future trajectory of the fertility transition are discussed. It is argued that the fertility transition may be more leisurely in the near future than in the recent past. Among the factors working against future fertility decline are the stability in the infant mortality rate, the stall in fertility desires, and the low patronage of modern contraceptives especially in rural areas. Copyright © 2006 John Wiley & Sons, Ltd. [source] Growth and body composition of juvenile white shrimp, Litopenaeus vannamei, fed different ratios of dietary protein to energyAQUACULTURE NUTRITION, Issue 6 2008Y. HU Abstract A 10-week feeding experiment was conducted to evaluate the effect of different protein to energy ratios on growth and body composition of juvenile Litopenaeus vannamei (initial average weight of 0.09 ± 0.002 g, mean ± SE). Twelve practical test diets were formulated to contain four protein levels (300, 340, 380 and 420 g kg,1) and three lipid levels (50, 75 and 100 g kg,1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The water temperature was 28.5 ± 2 °C and the salinity was 28 ± 1 g L,1 during the experimental period. The results showed that the growth was significantly (P < 0.05) affected by dietary treatments. Shrimps fed the diets containing 300 g kg,1 protein showed the poorest growth. However, shrimp fed the 75 g kg,1 lipid diets had only slightly higher growth than that fed 50 g kg,1 lipid diets at the same dietary protein level, and even a little decline in growth with the further increase of dietary lipid to 100 g kg,1. Shrimp fed the diet with 420 g kg,1protein and 75 g kg,1 lipid had the highest specific growth rate. However, shrimp fed the diet with 340 g kg,1 protein and 75 g kg,1 lipid showed comparable growth, and had the highest protein efficiency ratio, energy retention and feed efficiency ratio among dietary treatments. Triglycerides and total cholesterol in the serum of shrimp increased with increasing dietary lipid level at the same dietary protein level. Body lipid and energy increased with increasing dietary lipid level irrespective of dietary protein. Results of the present study showed that the diet containing 340 g kg,1 protein and 75 g kg,1 lipid with digestible protein/digestible energy of 21.1 mg kJ,1 is optimum for L. vannamei, and the increase of dietary lipid level has not efficient protein-sparing effect. [source] | |||||||||||||