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Mixed Response (mixed + response)
Selected AbstractsSite productivity and plant size explain the response of annual species to grazing exclusion in a Mediterranean semi-arid rangelandJOURNAL OF ECOLOGY, Issue 2 2004Yagil Osem Summary 1The response of an annual plant community to protection from grazing as a function of variation in site productivity was studied in a semi-arid Mediterranean rangeland in Israel over 4 years (1996,99). The abundance of species was compared in grazed vs. ungrazed plots (exclosures) in four neighbouring topographic sites (south- and north-facing slopes, hilltop and Wadi shoulders), representing a gradient of resource availability and productivity. 2Above-ground potential productivity at peak standing crop in spring (i.e. inside exclosures) varied considerably between years and topographic sites. Productivity was similar among the hilltop, south- and north-facing slopes, and was typical of semi-arid ecosystems (10,200 g,2). Productivity in the Wadi was consistently greater (up to 700 g,2) and reached the range of subhumid grassland ecosystems. 3The effect of grazing exclusion on the composition of the annual vegetation was productivity-dependent. Lower similarity (Sorenson's quantitative similarity index) between grazed and ungrazed subplots was observed in the productive Wadi compared with the less productive sites. The small-scale variation in grazing impact on species composition, due to differences in productivity, is consistent with models predicting similar trends in perennial grasslands across larger scale gradients. 4The relationship between plant size (above-ground dry-weight), site productivity and response to fencing was analysed for the 36 most abundant annual species. Large species were more abundant in more productive sites, and small species at lower productivity, although few species were restricted to particular productivity levels. The response of individual species to protection from grazing was productivity dependent, with plant size playing a central role. Larger species tended to increase and small ones to decrease in abundance after fencing, with a mixed response in species with intermediate size. 5A conceptual model is presented relating the response to protection from grazing along gradients of productivity to species plant size. [source] Phase I study of paclitaxel with standard dose ifosfamide in children with refractory solid tumors: A Pediatric Oncology Group study (POG 9376)PEDIATRIC BLOOD & CANCER, Issue 3 2009James I. Geller MD Abstract Purpose A dose-escalation Phase I study of taxol (paclitaxel) administered in combination with standard dose ifosfamide was conducted in children with relapsed or refractory solid tumors. Primary objectives were to estimate the maximum tolerated dose (MTD) and to describe the dose-limiting toxicities (DLTs). Patients and Methods Paclitaxel was administered as a 6-hr continuous infusion (hr 0,6), followed by intravenous ifosfamide (2 g/m2/day,×,3 days) over 1 hr at hours 6,7, 24,25, and 48,49. Patients at dose level 1 received 250 mg/m2 paclitaxel. Subsequent dose escalation proceeded using a standard 3,×,3 Phase I design. Results Fifteen patients received a combined 46 courses of therapy. The median age was 14.5 years (range, 2,19 years), and diagnoses included sarcoma (7), neuroblastoma (3), and other (5). Three patients received paclitaxel at 250 mg/m2 (10 courses), six at 325 mg/m2 (19 courses), three at 425 mg/m2 (8 courses), and three at 550 mg/m2 (9 courses). DLTs occurred in 2/3 patients at 550 mg/m2 paclitaxel during cycle 1, including grade 3 hypotension and grade 4 anaphylaxis in 1 patient each. Common non-dose-limiting toxicities included bone marrow suppression and peripheral neuropathy. Response was evaluable in 14 patients and included mixed response (3), stable disease (5), and progressive disease (6). Conclusion Paclitaxel hypersensitivity reactions were dose limiting when the drug was administered as a 6-hr infusion. The MTD and recommended Phase II dose of paclitaxel administered as a 6-hr continuous intravenous infusion followed by standard dose intravenous ifosfamide is 425 mg/m2 paclitaxel. Pediatr Blood Cancer 2009;52:346,350. © 2008 Wiley-Liss, Inc. [source] Physiologic neurocirculatory patterns in the head-up tilt test in children with orthostatic intolerancePEDIATRICS INTERNATIONAL, Issue 2 2008Zhang Qingyou Abstract Background: Orthostatic intolerance (OI) is a common clinical manifestation in clinical pediatrics. The head-up tilt (HUT) table test is considered the standard of orthostatic assessment, but the physiologic neurocirculatory profile during HUT has not been fully realized in children with OI. The present study, therefore, was designed to investigate the physiologic patterns that occur during HUT in children with OI. Methods: Ninety children (56 girls; mean age, 11.6 ± 2.3 years) with OI underwent HUT under quiet circumstances. Blood pressure and heart rate were monitored simultaneously. Results: Forty-nine children with OI (54.4%) had vasovagal response with HUT testing; 33 (36.7%), vasodepressor response; six (6.7%), cardioinhibitory response; and 10 (11.1%), mixed response. Twenty-eight children (31.1%) had postural orthostatic tachycardia; one (1.1%), orthostatic hypotension (OH); and 12 (13.3%), normal physiologic response. Patterns of cerebral syncope response and chronotropic incompetence were not observed. Conclusions: Classical vasovagal response was the major physiologic pattern seen in children with OI during HUT testing, and postural orthostatic tachycardia response ranked second. [source] Ecological responses to altered flow regimes: a literature review to inform the science and management of environmental flowsFRESHWATER BIOLOGY, Issue 1 2010N. LEROY POFF Summary 1.,In an effort to develop quantitative relationships between various kinds of flow alteration and ecological responses, we reviewed 165 papers published over the last four decades, with a focus on more recent papers. Our aim was to determine if general relationships could be drawn from disparate case studies in the literature that might inform environmental flows science and management. 2.,For all 165 papers we characterised flow alteration in terms of magnitude, frequency, duration, timing and rate of change as reported by the individual studies. Ecological responses were characterised according to taxonomic identity (macroinvertebrates, fish, riparian vegetation) and type of response (abundance, diversity, demographic parameters). A ,qualitative' or narrative summary of the reported results strongly corroborated previous, less comprehensive, reviews by documenting strong and variable ecological responses to all types of flow alteration. Of the 165 papers, 152 (92%) reported decreased values for recorded ecological metrics in response to a variety of types of flow alteration, whereas 21 papers (13%) reported increased values. 3.,Fifty-five papers had information suitable for quantitative analysis of ecological response to flow alteration. Seventy per cent of these papers reported on alteration in flow magnitude, yielding a total of 65 data points suitable for analysis. The quantitative analysis provided some insight into the relative sensitivities of different ecological groups to alteration in flow magnitudes, but robust statistical relationships were not supported. Macroinvertebrates showed mixed responses to changes in flow magnitude, with abundance and diversity both increasing and decreasing in response to elevated flows and to reduced flows. Fish abundance, diversity and demographic rates consistently declined in response to both elevated and reduced flow magnitude. Riparian vegetation metrics both increased and decreased in response to reduced peak flows, with increases reflecting mostly enhanced non-woody vegetative cover or encroachment into the stream channel. 4.,Our analyses do not support the use of the existing global literature to develop general, transferable quantitative relationships between flow alteration and ecological response; however, they do support the inference that flow alteration is associated with ecological change and that the risk of ecological change increases with increasing magnitude of flow alteration. 5.,New sampling programs and analyses that target sites across well-defined gradients of flow alteration are needed to quantify ecological response and develop robust and general flow alteration,ecological response relationships. Similarly, the collection of pre- and post-alteration data for new water development programs would significantly add to our basic understanding of ecological responses to flow alteration. [source] Trend analysis of Indian summer monsoon rainfall at different spatial scalesATMOSPHERIC SCIENCE LETTERS, Issue 4 2009Subimal Ghosh Abstract The results obtained from a conventional trend analysis of the Indian summer monsoon rainfall over a larger region are contradicted when analysis is performed at a finer resolution because of spatial variability and heterogeneity in the rainfall pattern. The present study analyzes the trend of summer monsoon rainfall all over India at a finer spatial resolution (1° latitude × 1° longitude) to identify the places that have a significant trend in terms of both rainfall amount and occurrence. The results obtained from this study are compared with those of a recent study by Goswami et al. (2006), where trend analysis is performed over a larger region [Central India (CI); 10° latitude × 12° longitude; assumed to be homogeneous in that study]. The increasing trend of occurrence of heavy rainfall and decreasing trend of occurrence of moderate rainfall, as concluded from that study, are contradicted by the present results for some places in CI. The present analysis shows spatially varying mixed responses of global warming toward rainfall occurrence and amounts all over India. The perception of increase in daily rainfall amount and occurrence due to climate change is found to be not correct for some of the regions in India. The possible reason may be the spatial variability of local changes such as rapid urbanization, industrialization and deforestation. Copyright © 2009 Royal Meteorological Society [source] | |||||||||||||