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Important Driving Force (important + driving_force)
Selected AbstractsPHYLOGEOGRAPHY AND DEMOGRAPHY OF SYMPATRIC SISTER SURFPERCH SPECIES, EMBIOTOCA JACKSONI AND E. LATERALIS ALONG THE CALIFORNIA COAST: HISTORICAL VERSUS ECOLOGICAL FACTORSEVOLUTION, Issue 2 2005Glacomo Bernardi Abstract With 18 closely related endemic species that radiated in a diversity of ecological niches, the California surfperches (Embiotocidae) species flock is a good candidate for the study of sympatric speciation. Resource partitioninghas been suggested as an important driving force in the radiation of the surfperch family. Within the family, two congeneric sister species, Embiotoca jacksoni and E. lateralis, are known to compete strongly for a preferred singleood resource and may be used as a model of ecological interactions for the family. Along the California coast, the distribution of the two species differs. Embiotoca jacksoni has a continuous range, whereas E. lateralis shows a disjunction with a distribution gap in the Southern California Bight. Two hypotheses may explain this disjunct distribution. Ecological competition may have displaced E. lateralis in favor of E. jacksoni. Alternatively, a common vicariant event may have separated the species into northern and southern populations, followed by secondary contactin E. jacksoni but not in E. lateralis. The two hypotheses predict different phylogeographic and demographic signatures. Using a combined phylogeographic and coalescent approach based on mitochondrial control region data, we show that vicariance can only account for a portion of the observed divergences. Our results are compatible with a significant role played by ecological competition in the southern range of the species. [source] Impact of land use changes on mountain vegetationAPPLIED VEGETATION SCIENCE, Issue 2 2002Erich Tasser Abstract. In this study the impact of land use changes on vegetation in the sub-alpine-alpine belt is analysed. The study sites (4.7 km2) are located in the Passeier Valley (South Tyrol, Italy), at an elevation of 1500,2300 m a.s.l. The whole study area was used for hay-making ca. 60 yr ago. Today, part of the meadows are more intensively used, while other parts have been converted to pasture or have been abandoned. We analysed the reasons for these land use changes and the effects on vegetation with a Geographical Information System and geostatistical analysis. The result of these analyses are: (1) Current land use is mainly controlled by the degree of accessibility for vehicles. Accessible areas are being used more and more intensively, while poorly accessible areas are being abandoned or used as pasture. (2) Current vegetation is highly determined by current land use. Particular vegetation units can be assigned to each form of land use. (3) Succession starts immediately after abandonment. Depending on altitude, succession proceeds at different speeds and with different numbers of stages. Hence the type of vegetation indicates the time passed since abandonment. (4) Land use changes lead to characteristic changes in vegetation; they are considered to be the most important driving force for vegetation change. (5) Measures of intensification and abandonment of extensively used areas both lead to a decrease in the number of species. [source] Mouse dendritic cells matured by ingestion of apoptotic blebs induce T cells to produce interleukin-17ARTHRITIS & RHEUMATISM, Issue 8 2009Justin H. Fransen Objective Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the formation of antinuclear autoantibodies. Increased apoptosis and reduced clearance of apoptotic material have been assigned a role in the pathogenesis of SLE, but the underlying mechanisms remain elusive. During apoptosis apoptotic blebs are formed in which autoantigens are clustered. The cellular remnants after blebbing are referred to as apoptotic cell bodies. We undertook this study to compare the effects of apoptotic blebs and apoptotic cell bodies on maturation of dendritic cells (DCs) and their T cell stimulatory capacity in a murine setting. Methods The uptake by DCs of apoptotic blebs and apoptotic cell bodies was analyzed by flow cytometry and confocal microscopy. DC maturation and DC-induced T cell activation were determined by measuring expression of costimulatory molecules using flow cytometry and by measuring production of cytokines using enzyme-linked immunosorbent assay. Results DCs internalized apoptotic blebs more efficiently than apoptotic cell bodies. Incubation of DCs with apoptotic blebs resulted in increased CD40 and CD86 expression and increased interleukin-6 (IL-6) and tumor necrosis factor , production, while apoptotic cell bodies had no stimulatory effects. Using chloroquine, apoptotic bleb,induced DC maturation was shown to be independent of Toll-like receptors 3, 7, and 9. Interestingly, in cocultures with allogeneic T cells, bleb-matured DCs induced production of IL-2, interferon-,, and, in particular, IL-17, suggesting a Th1/Th17 response. Conclusion Apoptotic blebs, in contrast to apoptotic cell bodies, induce DC maturation, thereby providing DCs with increased Th17 cell stimulatory capacity. These data imply that apoptotic bleb,induced DC maturation represents an important driving force in the autoimmune response in SLE. [source] Negative Momentum Profit in Korea and its Sources,ASIA-PACIFIC JOURNAL OF FINANCIAL STUDIES, Issue 2 2009Joon Chae Abstract To analyze the negative momentum profit in Korea, we further divide the decomposition of Lo and MacKinlay (1990) into winners' and losers' auto- and cross-serial covariances. We find that the negative autocovariance and the positive cross-serial covariance in Lo and MacKinlay's decomposition are asymmetric between winners and losers. The negative autocovariance is mainly from losers and the positive cross-serial covariance mainly between past winners and current losers. By investigating time-series characteristics of auto-(cross-serial) covariances, we cannot observe any systematic change of auto-(cross-serial) covariances in the momentum period. Based upon the evidence in this paper, we argue that positive cross-serial covariance between past winners and current losers seems to be an important driving force behind the negative momentum profit in Korea. Therefore, investors' underreaction to market-wide information would be plausible explanation of the negative momentum profit. [source] Dynamic changes in the epigenomic state and nuclear organization of differentiating mouse embryonic stem cellsGENES TO CELLS, Issue 4 2007Satoru Kobayakawa Changes in nuclear organization and the epigenetic state of the genome are important driving forces for developmental gene expression. However, a strategy that allows simultaneous visualization of the dynamics of the epigenomic state and nuclear structure has been lacking to date. We established an experimental system to observe global DNA methylation in living mouse embryonic stem (ES) cells. The methylated DNA binding domain (MBD) and the nuclear localization signal (nls) sequence coding for human methyl CpG-binding domain protein 1 (MBD1) were fused to the enhanced green fluorescent protein (EGFP) reporter gene, and ES cell lines carrying the construct (EGFP-MBD-nls) were established. The EGFP-MBD-nls protein was used to follow DNA methylation in situ under physiological conditions. We also monitored the formation and rearrangement of methylated heterochromatin using EGFP-MBD-nls. Pluripotent mouse ES cells showed unique nuclear organization in that methylated centromeric heterochromatin coalesced to form large clusters around the nucleoli. Upon differentiation, the organization of these heterochromatin clusters changed dramatically. Time-lapse microscopy successfully captured a moment of dramatic change in chromosome positioning during the transition between two differentiation stages. Thus, this experimental system should facilitate studies focusing on relationships between nuclear organization, epigenetic status and cell differentiation. [source] The Urge to Merge: A Multiple-Case StudyNONPROFIT MANAGEMENT & LEADERSHIP, Issue 2 2002Martha Golensky The authors undertook a comparative study of three recent mergers of nonprofit organizations in a Midwestern urban center, within the context of political-economy theory. The research explored the impact of the same environmental factor, managed care, on the initial decisions by organizational leaders and the effects of these early decisions on subsequent actions taken to implement the merger. The study tested the authors' model of the motivations for merging, which proposes that the relationship between the decision-making style of the leadership and the internal and external resources of the prospective partners determines whether the merger is driven primarily by mission, practicality, stability, or fear. Although the findings provide initial support for the hypotheses derived from the model, a demonstration of the differences in the approach to the merger by each organization indicated that other factors emerged as important driving forces during the various phases of the process. [source] | |||||||||||||