1,121 research outputs found
Skistodiaptomus pallidus (Copepoda: Diaptomidae) establishment in New Zealand natural lakes, and its effects on zooplankton community composition
The North American calanoid copepod Skistodiaptomus pallidus is an emerging invader globally, with non-indigenous populations recorded from constructed waters in New Zealand, Germany and Mexico since 2000. We examined the effects of S. pallidus establishment on the zooplankton community of a natural lake, Lake Kereta, where it was first recorded in late-2008, coincident with releases of domestically cultured grass carp (Ctenopharyngodon idella). Although not present in any of our samples prior to August 2008, S. pallidus was found in all samples collected in the subsequent five years. ANOSIM indicated zooplankton community composition significantly differed between samples collected before and after S. pallidus invasion, whether the invader was included in the analysis or not. Zooplankton species affected most greatly were the copepods Calamoecia lucasi and Mesocyclops sp., which decreased in their relative importance, and the cladocerans Bosmina meridionalis and Daphnia galeata, which increased. Rotifer species were relatively unaffected. As the length of grass carp released were >6.5 cm, direct predatory effects by this species on the zooplankton community are unlikely. Associated reductions in macrophyte biomass could explain increases in the relative abundances of planktonic cladocerans (B. meridionalis and D. galeata). However, the effect of macrophyte reduction by grass carp on zooplankton communities is considered to be limited elsewhere, while the reduced macrophyte biomass cannot explain the decrease in relative abundance of the native planktonic calanoid copepod C. lucasi. Competition between C. lucasi and S. pallidus is the most compelling explanation for the reduction in importance of the native calanoid copepod species. Skistodiaptomus pallidus appears to have undergone a âboom-and-bustâ cycle in Lake Kereta, increasing in relative abundance in the first three years following establishment, before declining in importance
Representing composition, spatial structure and management intensity of European agricultural landscapes: A new typology
Comprehensive maps that characterize the variation in agricultural landscapes across Europe are lacking. In this paper we present a new Europe-wide, spatially-explicit typology and inventory of the diversity in composition, spatial structure and management intensity of European agricultural landscapes. Agricultural landscape types were characterized at a 1 k
Sexual dimorphism in adverse pregnancy outcomes - A retrospective Australian population study 1981-2011
Published: July 11, 2016Objectives: Sexual inequality starts in utero. The contribution of biological sex to the developmental origins of health and disease is increasingly recognized. The aim of this study was to assess and interpret sexual dimorphisms for three major adverse pregnancy outcomes which affect the health of the neonate, child and potentially adult. Methods: Retrospective population-based study of 574,358 South Australian singleton live births during 1981â2011. The incidence of three major adverse pregnancy outcomes [preterm birth (PTB), pregnancy induced hypertensive disorders (PIHD) and gestational diabetes mellitus (GDM)] in relation to fetal sex was compared according to traditional and fetus-at-risk (FAR) approaches. Results: The traditional approach showed male predominance for PTB [20â24 weeks: Relative Risk (RR) M/F 1.351, 95%-CI 1.274â1.445], spontaneous PTB [25â29 weeks: RR M/F 1.118, 95%-CI 1.044â1.197%], GDM [RR M/F 1.042, 95%-CI 1.011â1.074], overall PIHD [RR M/F 1.053, 95%-CI 1.034â1.072] and PIHD with term birth [RR M/F 1.074, 95%-CI 1.044â1.105]. The FAR approach showed that males were at increased risk for PTB [20â24 weeks: RR M/F 1.273, 95%-CI 1.087â1.490], for spontaneous PTB [25â29 weeks: RR M/F 1.269, 95%-CI 1.143â1.410] and PIHD with term birth [RR M/F 1.074, 95%-CI 1.044â1.105%]. The traditional approach demonstrated female predominance for iatrogenic PTB [25â29 weeks: RR M/F 0.857, 95%-CI 0.780â0.941] and PIHD associated with PTB [25â29 weeks: RR M/F 0.686, 95%-CI 0.581â0.811]. The FAR approach showed that females were at increased risk for PIHD with PTB [25â29 weeks: RR M/F 0.779, 95%-CI 0.648â0.937]. Conclusions: This study confirms the presence of sexual dimorphisms and presents a coherent framework based on two analytical approaches to assess and interpret the sexual dimorphisms for major adverse pregnancy outcomes. The mechanisms by which these occur remain elusive, but sex differences in placental gene expression and function are likely to play a key role. Further research on sex differences in placental function and maternal adaptation to pregnancy is required to delineate the causal molecular mechanisms in sex-specific pregnancy outcome. Identifying these mechanisms may inform fetal sex specific tailored antenatal and neonatal care.Petra E. Verburg, Graeme Tucker, Wendy Scheil, Jan Jaap H. M. Erwich, Gus A. Dekker, Claire Trelford Robert
Predictive ability of logistic regression, auto-logistic regression and neural network models in empirical land-use change modeling: a case study
The objective of this study is to compare the abilities of logistic, auto-logistic and artificial neural network (ANN) models for quantifying the relationships between land uses and their drivers. In addition, the application of the results obtained by the three techniques is tested in a dynamic land-use change model (CLUE-s) for the Paochiao watershed region in Taiwan. Relative operating characteristic curves (ROCs), kappa statistics, multiple resolution validation and landscape metrics were used to assess the ability of the three techniques in estimating the relationship between driving factors and land use and its subsequent application in land-use change models. The validation results illustrate that for this case study ANNs constitute a powerful alternative for the use of logistic regression in empirical modeling of spatial land-use change processes. ANNs provide in this case a better fit between driving factors and land-use pattern. In addition, auto-logistic regression performs better than logistic regression and nearly as well as ANNs. Auto-logistic regression and ANNs are considered especially useful when the performance of more conventional models is not satisfactory or the underlying data relationships are unknown. The results indicate that an evaluation of alternative techniques to specify relationships between driving factors and land use can improve the performance of land-use change models
Land system science and sustainable development of the earth system: A global land project perspective
Land systems are the result of human interactions with the natural environment. Understanding the drivers, state, trends and impacts of different land systems on social and natural processes helps to reveal how changes in the land system affect the functioning of the socio-ecological system as a whole and the tradeoff these changes may represent. The Global Land Project has led advances by synthesizing land systems research across different scales and providing concepts to further understand the feedbacks between social-and environmental systems, between urban and rural environments and between distant world regions. Land system science has moved from a focus on observation of change and understanding the drivers of these changes to a focus on using this understanding to design sustainable transformations through stakeholder engagement and through the concept of land governance. As land use can be seen as the largest geo-engineering project in which mankind has engaged, land system science can act as a platform for integration of insights from different disciplines and for translation of knowledge into action
State-of-the-art imaging for glioma surgery.
Diffuse gliomas are infiltrative primary brain tumors with a poor prognosis despite multimodal treatment. Maximum safe resection is recommended whenever feasible. The extent of resection (EOR) is positively correlated with survival. Identification of glioma tissue during surgery is difficult due to its diffuse nature. Therefore, glioma resection is imaging-guided, making the choice for imaging technique an important aspect of glioma surgery. The current standard for resection guidance in non-enhancing gliomas is T2 weighted or T2w-fluid attenuation inversion recovery magnetic resonance imaging (MRI), and in enhancing gliomas T1-weighted MRI with a gadolinium-based contrast agent. Other MRI sequences, like magnetic resonance spectroscopy, imaging modalities, such as positron emission tomography, as well as intraoperative imaging techniques, including the use of fluorescence, are also available for the guidance of glioma resection. The neurosurgeon's goal is to find the balance between maximizing the EOR and preserving brain functions since surgery-induced neurological deficits result in lower quality of life and shortened survival. This requires localization of important brain functions and white matter tracts to aid the pre-operative planning and surgical decision-making. Visualization of brain functions and white matter tracts is possible with functional MRI, diffusion tensor imaging, magnetoencephalography, and navigated transcranial magnetic stimulation. In this review, we discuss the current available imaging techniques for the guidance of glioma resection and the localization of brain functions and white matter tracts
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Lake surface temperature [in âState of the Climate in 2017â]
Observed lake surface water temperature anomalies
in 2017 are placed in the context of the recent
warming observed in global surface air temperature
by collating long-term in situ lake
surface temperature observations from some of the
worldâs best-studied lakes and a satellite-derived
global lake surface water temperature dataset. The
period 1996â2015, 20 years for which satellite-derived
lake temperatures are available, is used as the base
period for all lake temperature anomaly calculations
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