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Downward Movement (downward + movement)
Selected AbstractsExoenzyme activities as indicators of dissolved organic matter composition in the hyporheic zone of a floodplain riverFRESHWATER BIOLOGY, Issue 8 2010SANDRA M. CLINTON Summary 1. We measured the hyporheic microbial exoenzyme activities in a floodplain river to determine whether dissolved organic matter (DOM) bioavailability varied with overlying riparian vegetation patch structure or position along flowpaths. 2. Particulate organic matter (POM), dissolved organic carbon (DOC), dissolved oxygen (DO), electrical conductivity and temperature were sampled from wells in a riparian terrace on the Queets River, Washington, U.S.A. on 25 March, 15 May, 20 July and 09 October 1999. Dissolved nitrate, ammonium and soluble reactive phosphorus were also collected on 20 July and 09 October 1999. Wells were characterised by their associated overlying vegetation: bare cobble/young alder, mid-aged alder (8,20 years) and old alder/old-growth conifer (25 to >100 years). POM was analysed for the ash-free dry mass and the activities of eight exoenzymes (,-glucosidase, ,-glucosidase, , -N-acetylglucosaminidase, xylosidase, phosphatase, leucine aminopeptidase, esterase and endopeptidase) using fluorogenic substrates. 3. Exoenzyme activities in the Queets River hyporheic zone indicated the presence of an active microbial community metabolising a diverse array of organic molecules. Individual exoenzyme activity (mean ± standard error) ranged from 0.507 ± 0.1547 to 22.8 ± 5.69 ,mol MUF (g AFDM),1 h,1, was highly variable among wells and varied seasonally, with the lowest rates occurring in March. Exoenzyme activities were weakly correlated with DO, DOC and inorganic nutrient concentrations. 4. Ratios of leucine aminopeptidase : ,-glucosidase were low in March, May and October and high in July, potentially indicating a switch from polysaccharides to proteins as the dominant component of microbial metabolism. 5. Principal components analysis indicated that there were patch effects and that these effects were strongest in the summer. 6. DOM degradation patterns did not change systematically along hyporheic flowpaths but varied with overlying forest patch type in the Queets River hyporheic zone, suggesting that additional carbon inputs exist. We hypothesise that the most likely input is the downward movement of DOM from overlying riparian soils. Understanding this movement of DOM from soils to subsurface water is essential for understanding both the hyporheic metabolism and the carbon budget of streams and rivers. [source] Redistribution of archaeological assemblages in plowzonesGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 3 2008Marta Navazo Archaeological surface surveys have located open-air sites on cropland in the Sierra de Atapuerca (Burgos, Spain). To what degree agricultural disturbances have impacted archaeological site integrity is poorly defined and may greatly affect interpretations of prehistoric land use. This paper presents the results of three experiments concerned with the effects of tillage on artifact distribution, focusing specifically on lateral and vertical artifact displacement. We demonstrate highly variable horizontal displacement of artifacts by plowing and overall downward movement of lithic materials within the soil. This results in an expansion of site boundaries and reduction of surface artifact density, yielding a biased and unrepresentative picture of past human activity. More experimental studies are needed to better define agricultural disturbances to surface archaeological assemblages. © 2008 Wiley Periodicals, Inc. [source] Artificial Recharge Through a Thick, Heterogeneous Unsaturated ZoneGROUND WATER, Issue 3 2008John A. Izbicki Thick, heterogeneous unsaturated zones away from large streams in desert areas have not previously been considered suitable for artificial recharge from ponds. To test the potential for recharge in these settings, 1.3 × 106 m3 of water was infiltrated through a 0.36-ha pond along Oro Grande Wash near Victorville, California, between October 2002 and January 2006. The pond overlies a regional pumping depression 117 m below land surface and is located where thickness and permeability of unsaturated deposits allowed infiltration and saturated alluvial deposits were sufficiently permeable to allow recovery of water. Because large changes in water levels caused by nearby pumping would obscure arrival of water at the water table, downward movement of water was measured using sensors in the unsaturated zone. The downward rate of water movement was initially as high as 6 m/d and decreased with depth to 0.07 m/d; the initial time to reach the water table was 3 years. After the unsaturated zone was wetted, water reached the water table in 1 year. Soluble salts and nitrate moved readily with the infiltrated water, whereas arsenic and chromium were less mobile. Numerical simulations done using the computer program TOUGH2 duplicated the downward rate of water movement, accumulation of water on perched zones, and its arrival at the water table. Assuming 10 × 106 m3 of recharge annually for 20 years, a regional ground water flow model predicted water level rises of 30 m beneath the ponds, and rises exceeding 3 m in most wells serving the nearby urban area. [source] An empirical analysis of US and Japanese health insurance using age,period,cohort decompositionHEALTH ECONOMICS, Issue 5 2007Kosei Fukuda Abstract Aggregate data on household health insurance expenditure in the US and Japan that are classified by period and age are decomposed into age, period, and cohort effects by using the Bayesian cohort models. These models are developed to overcome the identification problem involved in cohort analysis. Despite the differences between the health insurance systems of the two countries, three interesting empirical findings are obtained. First, in both the countries, the age effects are the most influential, and the cohort effects have negligible influence. The latter provides a striking policy implication since the generational imbalance in social security expenditures is widely recognized in developed countries. Second, in both the countries, the period effects show a roughly upward trend. Finally, the age effects exhibit a roughly upward movement for all age groups in the US; however, in Japan, these effects show a downward movement for the 55,59 age group due to the changes in the health insurance system on retirement. Copyright © 2006 John Wiley & Sons, Ltd. [source] MMP-2, TIMP-2 and MT1-MMP are differentially expressed in lesional skin of melanocytic nevi and their expression is modulated by UVB-lightJOURNAL OF CUTANEOUS PATHOLOGY, Issue 7 2002S. Krengel Background:, In malignant melanoma, recent studies have demonstrated an important role of matrix-metalloproteinase 2 (MMP-2), its co-activating enzyme membrane-type matrix-metalloproteinase 1 (MT1-MMP), and the endogenous inhibitor of MMP-2, tissue-inhibitor of matrix metalloproteinase 2 (TIMP-2). Melanocytic nevi are benign neoplasms of the melanocytic lineage, but may exhibit dysplastic features that can be difficult to distinguish from early stage melanoma. As shown in earlier studies, nevi show important morphological and phenotypical changes in response to ultraviolet light (UVB) irradiation. Objective:, To clarify the role of MMP-2, TIMP-2 and MT1-MMP in UVB-irradiated vs. non-irradiated melanocytic nevi. Methods:, Immunohistochemical comparison of the MMP-2, TIMP-2 and MT1-MMP expression pattern. Results:, MMP-2 is expressed by lesional keratinocytes and its expression is up-regulated by UVB-irradiation. MMP-2 expression was not observed in melanocytic cells. TIMP-2, by contrast, is predominantly expressed by melanocytic nevus cells, and its expression is in part down-regulated by UVB-irradiation. MT1-MMP is expressed by basal keratinocytes and to a weaker extent by melanocytic nevus cells. Conclusions:, MMP-2 expression by keratinocytes in nevi probably represents the result of activation of keratinocyte turnover in lesional epidermis. MMP-2 could play a role in the downward movement of junctional nevus cells into the dermis. The reduction of TIMP-2 expression in melanocytic cells by UV-light together with the enhanced expression of MMP-2 in the adjacent epidermis may promote basement membrane degradation. The expression pattern of MT1-MMP in close proximity to epithelial,mesenchymal interfaces underlines the synergistic role of MT1-MMP in this process. [source] Short-term changes in temporomandibular joint function in subjects with cleft lip and palate treated with maxillary distraction osteogenesisORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 2 2008K Hashimoto Structured Abstract Authors,,, Hashimoto K, Otsuka R, Minato A, Sato-Wakabayashi M, Takada J, Inoue-Arai MS, Miyamoto JJ, Ono T, Ohyama K, Moriyama K Objectives,,, To investigate the short-term effects of maxillary distraction osteogenesis (DO) on temporomandibular joint (TMJ) function in 21 subjects with cleft lip and palate (CLP). Design,,, Morphological changes in the maxillofacial region were measured using lateral cephalometric radiographs taken immediately before (pre-DO) and after DO (post-DO) and 1 year after DO (1-year follow-up). A questionnaire was evaluated using a visual analog scale. A chi-square test was used to compare the prevalence of TMJ symptoms between pre-DO and 1-year follow-up. The Spearman correlation coefficient was used to determine the correlation between changes in cephalometric variables and TMJ symptoms in association with maxillary DO. Statistical significance was set at p < 0.05. Results,,, The ANB (anteroposterior relationship of the maxilla with the mandible) angle and the mandibular plane angle at pre-DO, post-DO, and 1-year follow-up were ,4.3°, +5.8°, +4.3° and 32.1°, 33.5°, 33.6°, respectively. The average amounts of anterior and downward movement of the maxilla at post-DO and 1-year follow-up were 8.3, ,1.3 and 0.9, 1.1 mm, respectively. The prevalence of TMJ symptoms showed no significant increase in association with maxillary DO. Moreover, there was no significant correlation between changes in cephalometric variables and TMJ symptoms. Conclusion,,, These results suggest that there was no short-term (i.e., up to 1 year after DO) effect of maxillary DO on TMJ function in subjects with CLP. [source] Intergenerational class mobility in contemporary Britain: political concerns and empirical findings1THE BRITISH JOURNAL OF SOCIOLOGY, Issue 4 2007John H. Goldthorpe Abstract In Britain in recent years social mobility has become a topic of central political concern, primarily as a result of the effort made by New Labour to make equality of opportunity rather than equality of condition a focus of policy. Questions of the level, pattern and trend of mobility thus bear directly on the relevance of New Labour's policy analysis, and in turn are likely be crucial to the evaluation of its performance in government. However, politically motivated discussion of social mobility often reveals an inadequate grasp of both empirical and analytical issues. We provide new evidence relevant to the assessment of social mobility , in particular, intergenerational class mobility , in contemporary Britain through cross-cohort analyses based on the NCDS and BCS datasets which we can relate to earlier cross-sectional analyses based on the GHS. We find that, contrary to what seems now widely supposed, there is no evidence that absolute mobility rates are falling; but, for men, the balance of upward and downward movement is becoming less favourable. This is overwhelmingly the result of class structural change. Relative mobility rates, for both men and women, remain essentially constant, although there are possible indications of a declining propensity for long-range mobility. We conclude that under present day structural conditions there can be no return to the generally rising rates of upward mobility that characterized the middle decades of the twentieth century , unless this is achieved through changing relative rates in the direction of greater equality or, that is, of greater fluidity. But this would then produce rising rates of downward mobility to exactly the same extent , an outcome apparently unappreciated by, and unlikely to be congenial to, politicians preoccupied with winning the electoral ,middle ground'. [source] Your Money or Your Life: Changing Job Quality in OECD CountriesBRITISH JOURNAL OF INDUSTRIAL RELATIONS, Issue 3 2005Andrew E. Clark Job quality may usefully be thought of as depending on both job values (how much workers care about different job outcomes) and the job outcomes themselves. Here, both cross-section and panel data are used to examine changes in job quality in OECD countries during the 1990s. Despite rising wages and falling hours of work, overall job satisfaction is either stable or declining. These movements are neither due to changes in the type of workers nor because of changes in their job values. Some pieces of evidence point to stress and hard work as being strong candidates for what has gone wrong with employees' jobs. We find evidence of increasing inequality in a number of job outcomes. Some groups of workers have done better than others: the young and the highly educated have been insulated against downward movements in job quality, and there is tentative evidence that trade unions may have protected their members against adverse job outcomes. [source] | ||||||||||