bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of vestibular input on spatial and nonspatial memory and on hippocampal NMDA receptors
Authors: Besnard S. , Machado M.L. , Vignaux G. , Boulouard M. , Coquerel A. , Bouet V. , Freret T. , Denise P. , Lelong‐Boulouard V.
Published: April 2011

It has recently been shown that a lack of vestibular sensory information decreases spatial memory performance and induces biochemical changes in the hippocampus in rodents. After vestibular neurectomy, patients display spatial memory deficit and hippocampal atrophy. Our objectives were to explore: (a) spatial (Y maze, radial‐arm maze), and non‐spatial (object recognition) memory performance, (b) modulation of NMDA receptors within the hippocampus using radioligand binding, and (c) hippocampal atrophy, using MRI, in a rat model of bilateral labyrinthectomy realized in two operations. Chemical vestibular lesions (VLs) were induced in 24 animals by transtympanic injections of sodium arsanilate (30 mg/0.1 ml/ear), one side being lesioned 3 weeks after the other. The control group received transtympanic saline solution (0.1 ml/ear) (n= 24). Spatial memory performance (Y maze and radial maze) decreased after VL. Conversely, non‐spatial memory performance (object recognition) was not affected by VL. No hippocampal atrophy was observed with MRI, but density of NMDA receptors were increased in the hippocampus after VL. These findings show that the lack of vestibular information induced specific deficits in spatial memory. Additionally, quantitative autoradiographic data suggest the involvement of the glutamatergic system in spatial memory processes related to vestibular information. When studying spatial memory performances in the presence of vestibular syndrome, two‐step labyrinthectomy is a suitable procedure for distinguishing between the roles of the specific components of vestibular input loss and those of impaired locomotor activity. © 2011 Wiley Periodicals, Inc.
A broad‐scale assessment of the effect of improved soil management on catchment baseflow index
Authors: Holman I. P. , Hess T. M. , Rose S. C.
Published: April 2011

Although the importance of sustainable soil management is recognized, there are many threats to soils including widespread soil structural degradation. This reduces infiltration through the soil surface and/or the percolation of water through the soil profile, with important consequences for crop yields, nutrient cycling and the hydrological response of catchments. This article describes a broad‐scale modelling approach to assess the potential effect that improved agricultural soil management, through reduced soil structural degradation, may have on the baseflow index (BFI) of catchments across England and Wales. A daily soil–water balance model was used to simulate the indicative BFI of 45 696 thirty‐year model runs for different combinations of soil type, soil/field condition, land cover class and climate which encapsulate the variability across England and Wales. The indicative BFI of catchments was then calculated by upscaling the results by spatial weighting. WaSim model outputs of indicative BFI were within the 95% confidence intervals of the national‐average BFI values given for the Hydrology of Soil Type (HOST†) classes for 26 of the 28 classes. At the catchment scale, the concordance correlation coefficient between the BFI from the WaSim model outputs and those derived from HOST was 0·83. Plausible improvements in agricultural soil/field condition produced modest simulated increases of up to 10% in the indicative BFI in most catchments across England and Wales, although for much of southern and northern England the increases were less than 5%. The results suggest that improved soil management might partially mitigate the expected adverse effects of climate change on baseflow to rivers. Healthy, well‐functioning soils produce many additional benefits such as better agricultural yields and reduced pollutant movement, so improved soil management should provide win‐win opportunities for society, agricultural systems and the environment and provide resilience to some of the expected environmental impacts of climate change. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization of the infiltration rate in Las Tablas de Daimiel National Park, Central Spain
Authors: Navarro Vicente , García Beatriz , Asensio Laura
Published: April 2011

This article presents the characterization of the infiltration rate in the area known as ‘Las Cañas’ which is part of Las Tablas de Daimiel National Park, Central Spain. Available information was used for direct identification and while the results varied widely, it was proven that a functional dependence exists between the infiltration rate and the inundated area. After examining the structure of this dependence more closely, the most appropriate model was deemed to be a bilinear model. With these basic foundations, data from years 1997, 1998, 2003 and 2005 were used to identify the three parameters of the model. Highly satisfactory identifications were obtained. The model was then calibrated and the drying processes from 1996, 2000 and 2003 were simulated with considerable accuracy since the standard deviation was only 4 ha for a total of 400 inundated ha. The model was used to estimate the evolution that the inundated area would undergo after introducing contributions of treated sewage effluents. Even though it was assumed that the results would entail twice as many errors as the standard deviation, they did, however, allow us to provide a concise description of the behaviour of the system. Consequently, elements of judgement that highlight the advisability of the application of treated sewage effluents in Las Cañas, from a hydrological standpoint, were obtained. Copyright © 2011 John Wiley & Sons, Ltd.
Quantifying trends in indicator hydroecological variables for regime‐based groups of Canadian rivers
Authors: Monk Wendy A. , Peters Daniel L. , Allen Curry R. , Baird Donald J.
Published: April 2011

As a key contribution to Canada's Ecosystem Status and Trends (ESTR) national assessment, the goal of our study was to utilize available flow data as a surrogate of habitat suitability for aquatic ecological communities, and examine temporal trends in hydroecological variables over the 1970–2005 period. Daily flow data were extracted from the Reference Hydrological Basin Network, and an agglomerative hierarchical classification method was used to identify homogenous regions with similar seasonality of the flow regime. Six regime regions were identified reflecting the timing of the annual peaks and low flows in addition to the patterns in the rising and falling limbs. For each of the gauging station sites, the magnitude, duration, timing, frequency, and rate of change of annual hydrological events were quantified through 32 ecologically important hydrological variables. Long‐term patterns in the hydroecological variables were quantified using the nonparametric Mann‐Kendall trend statistic. The results revealed more trends than would be expected to occur by chance for most variables. Clear regional trend patterns were observed within individual regime groups demonstrating the often differing response to environmental variability within the different regions. Results at the national scale were highly variable, but trends towards increased variability in river flows were observed with a predominant increasing trend in the number of flow reversals over the water year and decreasing trend in the annual low‐flow indices. The identified river regime regions offer an initial framework for scientific investigation of hydroecological patterns and an opportunity to move towards a more predictive approach to environmental flows assessment in sustainable resource management and planning. Copyright © 2011 John Wiley & Sons, Ltd.
Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India
Authors: Garg Kaushal K. , Karlberg Louise , Barron Jennie , Wani Suhas P. , Rockstrom Johan
Published: April 2011

The paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India, developed through integrated management and a consortium approach. The impacts of various soil and water management interventions in the watershed are compared to no‐intervention during a 30‐year simulation period by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge and outflow under no‐intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by 10–30% and better crop yields compared to no‐intervention. Water outflows from the developed watershed were more than halved compared to no‐intervention, indicating potentially large negative downstream impacts if these systems were to be implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams were less than one‐tenth. It can be concluded that the hydrological impacts of large‐scale implementation of agricultural water interventions are significant. They result in improved rain‐fed agriculture and improved productivity and livelihood of farmers in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case‐specific studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at the mesoscale. Copyright © 2011 John Wiley & Sons, Ltd.
Trends in reference evapotranspiration in the humid region of northeast India
Authors: Jhajharia Deepak , Dinpashoh Yagob , Kahya Ercan , Singh Vijay P. , Fakheri‐Fard Ahmad
Published: April 2011

In the present study, the trends in the reference evapotranspiration (ETO) estimated through the Penman‐Monteith method were investigated over the humid region of northeast (NE) India by using the Mann‐Kendall (MK) test after removing the effect of significant lag‐1 serial correlation from the time series of ETO by pre‐whitening. During the last 22 years, ETO has been found to decrease significantly at annual and seasonal time scales for 6 sites in NE India and NE India as a whole. The seasonal decreases in ETO have, however, been more significant in the pre‐monsoon season, indicating the presence of an element of a seasonal cycle. The decreases in ETO are mainly attributed to the net radiation and wind speed, which are also corroborated by the observed trends in these two parameters at almost all the times scales over most of the sites in NE India. The steady decrease in wind speed and decline in net radiation not only balanced the impact of the temperature increases on ETO, but may have actually caused the decreases in ETO over the humid region of northeast India. Copyright © 2011 John Wiley & Sons, Ltd.
Modelling and analysis of the impact of irrigation on local arid climate over northwest China
Authors: Wen Lijuan , Jin Jiming
Published: April 2011

This study focuses on how irrigation processes affect local climate over arid areas. The chosen study area is northwest China, a typical arid region where three dominant land‐use types are irrigated cropland, grassland, and desert. Observational analysis indicates that the highest precipitation, the coolest surface temperatures, and the slowest warming trend are seen over irrigated cropland from 1979 to 2005. The single column atmospheric model (SCAM), developed by the National Center for Atmospheric Research (NCAR), was used to investigate and better understand the differences in long‐term climate conditions and change over the above three land‐use types. The results indicate that local climate conditions are predominantly controlled by large‐scale forcing in this arid region and that local land surface forcing related to vegetation cover change and irrigation processes also has a significant impact. This study strongly suggests that a realistic climate forecast for this region can be achieved only with both accurate large‐scale and local climate forcing. The irrigated cropland of the region generates stronger evaporation that cools the surface and slows the warming trend more than does the evaporation from the natural grassland and desert. Stronger evaporation also significantly increases precipitation, potentially alleviating the stress of irrigation demands in arid regions. A series of sensitivity SCAM simulations indicate that a drier and warmer climate occurs with decreasing vegetation cover in the irrigated cropland region. Copyright © 2011 John Wiley & Sons, Ltd.
Internal structure and hydrological functions of an alpine proglacial moraine
Authors: Langston Gregory , Bentley Laurence R. , Hayashi Masaki , McClymont Alastair , Pidlisecky Adam
Published: April 2011

Understanding groundwater processes in alpine watersheds is critical to understand the timing of water release and late‐season stream flow for both headwater and downstream environments. Moraines and talus features can play an important role in groundwater flow and storage processes in alpine watersheds, but neither process is well understood for these features. We examined the complex hydrogeological environment of a partially ice‐cored moraine in the Lake O'Hara watershed in the Canadian Rockies. Electrical resistivity imaging (ERI) and seismic refraction tomography delineated regions of buried ice and frozen and unfrozen moraine material. Seismic refraction data also clearly indicated the depth to bedrock, which varied primarily due to the thickness of the overlying moraine material. Water levels in a lake and several tarns on the moraine responded differently to inputs of rain, snowmelt, and glacier melt, indicating the different degree of hydrological connectivity of these features to the groundwater flow system in the moraine. Such differences reflect the effects of bedrock topography and the location and geometry of buried ice. Ground‐penetrating radar images and ERI indicated regions of perched groundwater and focused infiltration. The location of these regions appears to be controlled by buried ice. All geophysical and hydrological data suggest that a relatively thin (<5 m) layer of saturated sediments and/or fractured bedrock likely provides a major flow system within the moraine. Copyright © 2011 John Wiley & Sons, Ltd.
Assessment on variability of extreme climate events for the Upper Thames River basin in Canada
Authors: Eum Hyung‐Il , Simonovic Slobodan P.
Published: April 2011

Climate change may affect magnitude and frequency of regional extreme events with possibility of serious impacts on the existing infrastructure systems. This study investigates how the current spatial and temporal variations of extreme events are affected by climate change in the Upper Thames River basin, Ontario, Canada. A weather generator model is implemented to obtain daily time series of three climate variables for two future climate scenarios. The daily time series are disaggregated into hourly to capture characteristics of intense and rapidly changing storms. The maximum annual precipitation events for five short durations, 6‐, 12‐, 24‐, 48‐, and 72‐h durations, at each station are extracted from the generated hourly data. The frequency and seasonality analyses are conducted to investigate the temporal and spatial variability of extreme precipitation events corresponding to each duration. In addition, this study investigates the impacts of increase in temperature using reliability, resilience, and vulnerability. The results indicate that the extreme precipitation events under climate change will occur earlier than in the past. In addition, episodes of extremely high temperature may last longer up to 19·7% than under the no‐change climate scenario. This study points out that the revision of the design storms (e.g. 100‐ or 250‐year return period) is warranted for the west and the south east region of the basin. Copyright © 2011 John Wiley & Sons, Ltd.
The influence of dam and lakes on the Yangtze River streamflow: long‐range correlation and complexity analyses
Authors: Zhang Qiang , Zhou Yu , Singh Vijay P. , Chen Xiaohong
Published: April 2011

Employing long‐range correlation, complexity features and clustering, this study investigated the influence of dam and lake‐river systems on the Yangtze River flow. The impact of the Gezhouba Dam and the lake systems on streamflow was evaluated by analysing daily streamflow records at the Cuntan, the Yichang and the Datong station. Results indicated no evident influence of the Gezhouba Dam on streamflow changes. Distinct differences in scaling behaviour, long‐range correlation and clustering of streamflow at the Datong station when compared with those at the Cuntan and Yichang stations undoubtedly showed the influence of water storage and the buffering effect of the lake systems between the Datong station and other two hydrological stations on streamflow in the lower Yangtze River basin. Decreased regularity, enhanced long‐range correlation and increased clustering of streamflow in the lower Yangtze River basin due to the effect of water storage of the lake systems were corroborated. Copyright © 2011 John Wiley & Sons, Ltd.
Quantification of incoming all‐wave radiation in discontinuous forest canopies with application to snowmelt prediction
Authors: Lawler Robert R. , Link Timothy E.
Published: April 2011

Snowmelt dynamics in forested areas are largely driven by net radiation, which is controlled by solar elevation angle and spatial variations in canopy structure. Understanding of the spatiotemporal radiative regimes in discontinuous forests during the snow season is limited. To improve understanding of radiation dynamics in discontinuous forests, a theoretical, spatially explicit, all‐wave irradiance model was developed. The model was tested using detailed measurements collected with radiometer arrays consisting of 16 pyranometers and 14 pyrgeometers installed in a small forest canopy gap. The model was used to simulate incoming radiation over the snow season at mid‐latitude (47°N), level forest canopy gaps with diameters ranging from one to six times the surrounding tree heights (H). Theoretical results indicate that radiative regimes in small canopy gaps may be distinctly different from continuous open areas and closed‐canopy forests, especially at low solar elevation angles. At low sun angles, spatial radiative minima can occur in gaps due to low incoming shortwave radiation caused by canopy shading, coupled with minimal longwave radiation enhancement from surrounding forests. At 47°N latitude on 1 February, simulated incoming all‐wave radiation in canopy gaps was less than both open and forested areas over 100 to 33% of north‐south transects ranging from 25 to 150 m in 1H to 6H gaps, respectively. By 1 May, the zone of radiative minima in 1H to 6H gaps ranged from 44 to 8%, respectively. The outcome of this work is an enhanced understanding of radiation variability in discontinuous forest canopies during the snow season. Copyright © 2011 John Wiley & Sons, Ltd.
Influence of a thin veneer of low‐hydraulic‐conductivity sediment on modelled exchange between river water and groundwater in response to induced infiltration
Authors: Rosenberry Donald O. , Healy Richard W.
Published: April 2011

A thin layer of fine‐grained sediment commonly is deposited at the sediment–water interface of streams and rivers during low‐flow conditions, and may hinder exchange at the sediment–water interface similar to that observed at many riverbank‐filtration (RBF) sites. Results from a numerical groundwater‐flow model indicate that a low‐permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5–10% when a 2‐cm thick, low‐permeability veneer is present on the bed surface. Increasing thickness of the low‐permeability layer to 0·1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three‐orders‐of‐magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field‐measured values that were on the order of a factor of 20–25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low‐permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low‐permeability sediment veneer, as well as central‐pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells. Published in 2011 by John Wiley & Sons, Ltd.
Sensitivity of the snowcover energetics in a mountain basin to variations in climate
Authors: Reba Michele L. , Marks Danny , Winstral Adam , Link Timothy E. , Kumar Mukesh
Published: April 2011

Snow is an important natural reservoir that holds water on the landscape for release later in the season in western North America and other portions of the world. As air temperature increases with global climate change, the character of the generally established seasonal snowcover will be affected. To study the specific response to variable climate, a carefully collected and processed meteorological data set for the 1984–2008 water years (WYs) was assembled for a snow‐dominated headwater mountain catchment. The data were used to force a physically based, distributed energy balance snow model to simulate patterns of snow deposition and melt over the catchment for the 25‐year period. This period covers both the highest (1984) and lowest (1992) snow seasons on record and exhibits extreme inter‐annual variability. This unique forcing data set captured meteorological conditions that resulted in the range of variability in snowcover accumulation, timing of ablation, and the timing and amount of surface water input (SWI), and discharge during the 25‐year study period. SWI is the amount of liquid water delivered to the soil surface from melting snow or from rain that passes through the snowcover or falls directly on the soil. Warm winters, characterized by early‐ and mid‐winter rain, triggered earlier inputs from SWI and response in discharge than cool winters. Cool conditions prolonged the generation of SWI and streamflow out of the basin. Very wet conditions that were warm passed 50% of the SWI 27 days earlier and passed 50% of the discharge 15 days earlier, when compared to very wet conditions that were cool. Warmer conditions produced less snow water equivalent, shortened the melt season, and would be expected to extend the summer drought. Copyright © 2011 John Wiley & Sons, Ltd.
Modelling catchment‐scale shallow landslide occurrence and sediment yield as a function of rainfall return period
Authors: Bovolo C. I. , Bathurst J. C.
Published: April 2011

A model‐based method is proposed for improving upon existing threshold relationships which define the rainfall conditions for triggering shallow landslides but do not allow the magnitude of landsliding (i.e. the number of landslides) to be determined. The SHETRAN catchment‐scale shallow landslide model is used to quantify the magnitude of landsliding as a function of rainfall return period, for focus sites of 180 and 45 km2 in the Italian Southern Alps and the central Spanish Pyrenees. Rainfall events with intensities of different return period are generated for a range of durations (1‐day to 5‐day) and applied to the model to give the number of landslides triggered and the resulting sediment yield for each event. For a given event duration, simulated numbers of landslides become progressively less sensitive to return period as return period increases. Similarly, for an event of given return period, landslide magnitude becomes less sensitive to event duration as duration increases. The temporal distribution of rainfall within an event is shown to have a significant impact on the number of landslides and the timing of their occurrence. The contribution of shallow landsliding to catchment sediment yield is similarly quantified as a function of the rainfall characteristics. Rainfall intensity–duration curves are presented which define different levels of landsliding magnitude and which advance our predictive capability beyond, but are generally consistent with, published threshold curves. The magnitude curves are relevant to the development of guidelines for landslide hazard assessment and forecasting. Copyright © 2011 John Wiley & Sons, Ltd.
Bioaccumulation data from laboratory and field studies: Are they comparable?
Authors: Burkhard Lawrence P , Cowan-Ellsberry Christina , Embry Michelle R , Hoke Robert A , Kidd Karen A
Published: April 2011

Once they are released into the environment, a number of chemicals are known to bioaccumulate in organisms, sometimes to concentrations that may threaten the individual or their predators. However, use of physical or chemical properties or results from laboratory bioaccumulation tests to predict concentrations sometimes found in wild organisms remains a challenge. How well laboratory studies and field measurements agree or disagree, and the cause of any discrepancies, is a subject of great interest and discussion from both a scientific and a regulatory perspective. A workshop sponsored by the ILSI Health and Environmental Sciences Institute, US Environmental Protection Agency, and the Society of Environmental Toxicology and Chemistry assembled scientists from academia, industry, and government to compare and contrast laboratory and field bioaccumulation data. The results of this workshop are summarized in a series of 5 articles published in this issue of Integrated Environmental Assessment and Management. The articles describe: 1) a weight-of-evidence approach that uses fugacity ratios to bring field measurements into the assessment of biomagnification potential for legacy chemicals; 2) a detailed comparison between laboratory and field data for the most commonly measured bioaccumulation endpoint, the biota–sediment accumulation factor; 3) a study that identifies and quantifies the differences between laboratory and field metrics of bioaccumulation for aquatic and terrestrial organisms; and 4) 2 reports on trophic magnification factors: the 1st addresses how trophic magnification factors are determined and interpreted and the 2nd describes how they could be used in regulatory assessments. Collectively, these articles present the workshop participants' current understanding and assessment of bioaccumulation science and make a number of recommendations on how to improve the collection and interpretation of bioaccumulation data. Integr Environ Assess Manag 2012;8:13–16. © 2011 SETAC
Xplicit, a novel approach in probabilistic spatiotemporally explicit exposure and risk assessment for plant protection products
Authors: Schad Thorsten , Schulz Ralf
Published: April 2011

The quantification of risk (the likelihood and extent of adverse effects) is a prerequisite in regulatory decision making for plant protection products and is the goal of the Xplicit project. In its present development stage, realism is increased in the exposure assessment (EA), first by using real-world data on, e.g., landscape factors affecting exposure, and second, by taking the variability of key factors into account. Spatial and temporal variability is explicitly addressed. Scale dependencies are taken into account, which allows for risk quantification at different scales, for example, at landscape scale, an overall picture of the potential exposure of nontarget organisms can be derived (e.g., for all off-crop habitats in a given landscape); at local scale, exposure might be relevant to assess recovery and recolonization potential; intermediate scales might best refer to population level and hence might be relevant for risk management decisions (e.g., individual off-crop habitats). The Xplicit approach is designed to comply with a central paradigm of probabilistic approaches, namely, that each individual case that is derived from the variability functions employed should represent a potential real-world case. This is mainly achieved by operating in a spatiotemporally explicit fashion. Landscape factors affecting the local exposure of habitats of nontarget species (i.e., receptors) are derived from geodatabases. Variability in time is resolved by operating at discrete time steps, with the probability of events (e.g., application) or conditions (e.g., wind conditions) defined in probability density functions (PDFs). The propagation of variability of parameters into variability of exposure and risk is done using a Monte Carlo approach. Among the outcomes are expectancy values on the realistic worst-case exposure (predicted environmental concentration [PEC]), the probability p that the PEC exceeds the ecologically acceptable concentration (EAC) for a given fraction of habitats, and risk curves. The outcome can be calculated at any ecologically meaningful organization level of receptors. An example application of Xplicit is shown for a hypothetical risk assessment for nontarget arthropods (NTAs), demonstrating how the risk quantification can be improved compared with the standard deterministic approach. Integr Environ Assess Manag 2011;7:612–623. © 2011 SETAC
Development and evaluation of a dynamic model that projects population biomarkers of methylmercury exposure from local fish consumption
Authors: Chan Caroline , Heinbokel John F , Myers John A , Jacobs Robert R.
Published: April 2011

A dynamic model was developed to project Hg concentrations in common biomarkers of exposure in response to changes in Hg concentrations in predatory fish from local waters. The model predicts biomarkers in susceptible populations for intake rates representing the mean, 90th, 95th, and 99th percentiles of populations of interest. The biomarkers the model calculates are blood methylmercury, total hair Hg, and fetal blood methylmercury. Decision makers can use the model to determine the degree of reduction in fish tissue Hg levels necessary to protect the health of susceptible populations. Biomarker output was calibrated with literature sources. Output was then compared to additional literature sources to evaluate model function. Projected biomarkers were not different from literature sources. The model can be used as a tool to understand the impact of local fish consumption on susceptible populations. Integr Environ Assess Manag 2011;7:624–635. © 2011 SETAC
Use of trophic magnification factors and related measures to characterize bioaccumulation potential of chemicals
Authors: Conder Jason M , Gobas Frank A P C , Borgå Katrine , Muir Derek C G , Powell David E
Published: April 2011

Recent technical workgroups have concluded that trophic magnification factors (TMFs) are useful in characterizing the bioaccumulation potential of a chemical, because TMFs provide a holistic measure of biomagnification in food webs. The objectives of this article are to provide a critical analysis of the application of TMFs for regulatory screening for bioaccumulation potential, and to discuss alternative methods for supplementing TMFs and assessing biomagnification in cases where insufficient data are available to determine TMFs. The general scientific consensus is that chemicals are considered bioaccumulative if they exhibit a TMF > 1. However, comparison of study-derived TMF estimates to this threshold value should be based on statistical analyses such that variability is quantified and false positive and false negative errors in classification of bioaccumulation potential are minimized. An example regulatory decision-making framework is presented to illustrate the use of statistical power analyses to minimize assessment errors. Suggestions for considering TMF study designs and TMFs obtained from multiple studies are also provided. Alternative bioaccumulation metrics are reviewed for augmenting TMFs and for substituting in situations in which field data for deriving TMFs are unavailable. Field-derived, trophic level-normalized biomagnification factors (BMFTLs), biota–sediment accumulation factors (BSAFTLs), and bioaccumulation factors (BAFTLs) are recommended if data are available, because these measures are most closely related to the biomagnification processes characterized by TMFs. Field- and laboratory-derived BAFs and bioconcentration factors are generally less accurate in predicting biomagnification. However, bioconcentration factors and BAFs remain useful for characterizing bioaccumulation as a result of the transfer of chemicals from abiotic environmental compartments to lower trophic levels. Modeling that incorporates available laboratory and field data should also be considered for augmenting assessments of bioaccumulation potential. Modeling can provide a TMF-focused assessment for new or unreleased chemicals in the absence of field data by estimating TMF values and theoretical relationships between physical-chemical properties and TMF values (quantitative structure–activity relationships). An illustration of the use of physicochemical properties for estimating TMFs is provided. Overall, TMFs provide valuable information regarding bioaccumulation potential and should be incorporated into regulatory decision making following the suggestions outlined in this article. Integr Environ Assess Manag 2012;8:?–?. © 2011 SETAC
On the forecasting accuracy of multivariate GARCH models
Authors: Laurent Sébastien , Rombouts Jeroen V. K. , Violante Francesco
Published: April 2011

This paper addresses the question of the selection of multivariate generalized autoregressive conditional heteroskedastic (GARCH) models in terms of variance matrix forecasting accuracy, with a particular focus on relatively large‐scale problems. We consider 10 assets from the New York Stock Exchange and compare 125 models based 1‐, 5‐ and 20‐day‐ahead conditional variance forecasts over a period of 10 years using the model confidence set (MCS) and the superior predictive ability (SPA) tests. Model performance is evaluated using four statistical loss functions which account for different types and degrees of asymmetry with respect to over‐/under‐predictions. When considering the full sample, MCS results are strongly driven by short periods of high market instability during which multivariate GARCH models appear to be inaccurate. Over relatively unstable periods, i.e. the dot‐com bubble, the set of superior models is composed of sophisticated specifications such as orthogonal and dynamic conditional correlation (DCC), both with leverage effect in the conditional variances. However, unlike the DCC models, our results show that the orthogonal specifications tend to underestimate the conditional variance. Over calm periods, a simple assumption like constant conditional correlation and symmetry in the conditional variances cannot be rejected. Finally, during the 2007–2008 financial crisis, accounting for non‐stationarity in the conditional variance process generates superior forecasts. The SPA test suggests that, independently from the period, the best models do not provide significantly better forecasts than the DCC model of Engle (2002,Journal of Business and Economic Statistics20: 339–350) with leverage in the conditional variances of the returns. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and biological activities of a novel series of 3,6‐disubstituted‐1,2,4‐triazolo‐[3,4‐b]‐1,3,4‐thiadiazoles containing gem‐dimethylbenzyl moiety
Authors: Puthiyapurayil Pushpan , Poojary Boja , Kumar Sunil , Hunnur Raveendra
Published: April 2011

A novel series of 3,6‐disubstituted‐1,2,4‐triazolo‐[3,4‐b]‐1,3,4‐thiadiazoles (6a–r) containing gem‐dimethyl benzyl moiety were prepared by the condensation of 4‐amino‐3‐aryl/aralkyl substituted‐5‐mercapto‐1,2,4‐triazoles (5a, 5b, 5c) with various fluoro substituted aromatic acids in the presence of POCl3. IR, 1H NMR, 13C NMR, 2D NMR (COSY), and mass spectral data confirmed the structures of all the synthesized compounds. All the compounds were also screened for their antibacterial, antifungal and analgesic activities. Compounds 6b, 6d, 6f, 6g, 6h, 6i, 6m, 6n, 6o, 6p, and 6r exhibited promising antibacterial and compounds 6a, 6d, 6f, 6g, 6h, 6k, 6m, 6o, 6p, and 6q showed significant analgesic activities. J. Heterocyclic Chem., (2011)
A convenient synthesis of pyrrolo‐annelated 1,3‐diselenole‐2‐thione and 1,3‐diselenol‐2‐one derivatives via dipyrrolo‐annelated 1,2,5,6‐tetraselenocine derivatives
Authors: Park Joon Bum , Kim Ja Hong , Zong Kyukwan
Published: April 2011

The reaction of 2,5‐dimethyl‐3,4‐diselenocyanato‐1H‐pyrrole by NaBH4 or NaOCH3 led to tetraselenide 7 in quantitative yield. Treatment of protected tetraselenide 8 with LiAlH4 afforded the aluminum complex intermediate that was converted into pyrrole‐annelated 1,3‐diselenolo‐2‐thione 9 in excellent yield. Similarly, treatment of tetraselenide 8 with LiAlH4 followed by TFA afforded 1,2‐diselenol intermediate that was converted into pyrrole‐annelated 1,3‐diselenolo‐2‐one 10 upon treatment of diimidazole carbonate. J. Heterocyclic Chem., (2011).
Transcription and pathway analysis of the superior temporal cortex and anterior prefrontal cortex in schizophrenia
Authors: Barnes Michael R. , Huxley‐Jones Julie , Maycox Peter R. , Lennon Mark , Thornber Amy , Kelly Fiona , Bates Stewart , Taylor Adam , Reid Juliet , Jones Neil , Schroeder Jörn , Scorer Carol A. , Davies Ceri , Hagan Jim J. , Kew James N.C. , Angelinetta Claire , Akbar Tariq , Hirsch Steven , Mortimer Ann M. , Barnes Thomas R.E. , de Belleroche Jackie
Published: April 2011

The molecular basis of schizophrenia is poorly understood; however, different brain regions are believed to play distinct roles in disease symptomology. We have studied gene expression in the superior temporal cortex (Brodmann area 22; BA22), which may play a role in positive pathophysiology, and compared our results with data from the anterior prefrontal cortex (BA10), which shows evidence for a role in negative symptoms. Genome‐wide mRNA expression was determined in the BA22 region in 23 schizophrenics and 19 controls and compared with a BA10 data set from the same subjects. After adjustments for confounding sources of variation, we carried out GeneGO pathway enrichment analysis in each region. Significant differences were seen in age‐related transcriptional changes between the BA22 and the BA10 regions, 21.8% and 41.4% of disease‐associated transcripts showing age association, respectively. After removing age associated changes from our data, we saw the highest enrichment in processes mediating cell adhesion, synaptic contact, cytoskeletal remodelling, and apoptosis in the BA22 region. For the BA10 region, we observed the strongest changes in reproductive signalling, tissue remodelling, and cell differentiation. Further exploratory analysis also identified potentially disease‐relevant processes that were undetected in our more stringent primary analysis, including autophagy in the BA22 region and the amyloid process in the BA10 region. Collectively, our analysis suggests disruption of many common pathways and processes underpinning synaptic plasticity in both regions in schizophrenia, whereas individual regions emphasize changes in certain pathways that may help to highlight pathway‐specific therapeutic opportunities to treat negative or positive symptoms of the disease. © 2011 Wiley‐Liss, Inc.
Seasonal anomalous rainfall in the central and eastern Amazon and associated anomalous oceanic and atmospheric patterns
Authors: Andreoli Rita Valéria , Ferreira de Souza Rodrigo Augusto , Kayano Mary Toshie , Candido Luiz Antônio
Published: April 2011

Previous papers have shown that the rainfall anomalies over the Amazon region result from the independent or combined effects of the eastern tropical Pacific and Atlantic Basins. Here, the monthly rainfall data of Itaituba, Manaus, Parintins, and Santarém for the 1931–1996 period has been used to classify its dry and rainy seasons into dry, very dry, wet, and very wet categories. The sea surface temperature (SST) and sea level pressure (SLP) patterns associated with these climate conditions in the central and eastern Amazon are discussed in terms of the relative influence of the tropical Atlantic and Pacific sectors, as well as their seasonal differences. These seasonal differences are, in part, determined by the seasonal phase locking of the El Niño‐Southern Oscillation (ENSO) and Atlantic equatorial modes. The rainy season cases are mostly driven by the ENSO and the inter‐hemispheric SST gradient mode in the tropical Atlantic, and the dry season cases, by the Atlantic equatorial mode (AEM). A new result here is the role of the inter‐Pacific‐Atlantic anomalous SST gradient mode on the rainfall anomalies. This mode acts concordantly with the Atlantic modes on the rainfall over the central and eastern Amazon, and is responsible for precipitation extreme cases during the dry season and for the very wet rainy season case. In other words, the intense inter‐Pacific‐Atlantic mode for these cases is the differential factor in relation to the moderate cases. The results here, especially in relation to the role of the inter‐Pacific‐Atlantic gradient in the central and eastern Amazon precipitation, have not been discussed before and should be taken into consideration in the diagnostic activities. Copyright © 2011 Royal Meteorological Society
Summer night‐time temperature trends on the Iberian Peninsula and their connection with large‐scale atmospheric circulation patterns
Authors: Sanchez‐Lorenzo Arturo , Pereira Paulo , Lopez‐Bustins Joan A. , Lolis Christos J.
Published: April 2011

The present paper studies the variability and trends of Tropical Nights (>20 °C) (TNs) on the Iberian Peninsula (IP) over the 1961–2007 period during the extended summer (defined as June, July, August, and September, JJAS). The analyses were performed with the mean series calculated for the whole IP and for different subregions. We conducted a regionalisation by means of a S‐Mode Principal Component Analysis (PCA), which identified three subregions where the variability of TNs behaves similarly: the Mediterranean (M) region, the centre‐north of the Peninsula (CN) region, and the Atlantic (A) region. Throughout the entire period, the mean summer TN series for the whole IP shows a significant increase; there are, however, some regional differences, as the CN and M regions present higher rates of warming than the A region. Using Canonical Correlation Analysis (CCA) we detected the large‐scale atmospheric circulation patterns controlling the interannual variability of TNs over the IP. The occurrence of TNs in the M and CN subregions is highly dependent on anticyclonic conditions over Western Europe in the mid‐troposphere level. The increase in the positive phase of this canonical mode during the last three decades might explain part of the positive trend of the TNs detected in summer on the IP. Copyright © 2011 Royal Meteorological Society
Statistical analysis of freezing temperatures in Central and Southern Florida
Authors: Waylen Peter R.
Published: April 2011

The probability distributions of the number of freezing periods per year, their timing and severity are examined at 25 stations in southern and central Florida. The proposed distributions, derived from stochastic crossing theory, provide adequate fits with the exception of three variables at different stations. The estimated parameter values reflect the changing geography of the freeze hazard. The freeze variable that exhibits the greatest variability over the area appears to be the number of periods, while the average severity of freezes and their timings are fairly homogeneous. The theoretical basis of the method permits estimation of the distribution of the dates of first and last freezes and the distribution of the coldest temperature likely to be encountered during any period of interest. The risks of periods of extremely cold temperatures, rarely observed in the historic records, may also be obtained from those at the more commonly encountered level. The technique provides a thorough yet easily interpreted summary of cold‐spell risks at any location.
The role of radiation geometry in the climate response of mount kenya's glaciers, part 2: Sloping versus horizontal surfaces
Authors: Hastenrath Stefan , Kruss Phillip D.
Published: April 2011

This part of the study expands the modelling of incident solar radiation on Mount Kenya and its glaciers to include the behaviour for sloping as compared to horizontal surfaces. It is concluded that for the purposes of the ongoing climate study the broad‐scale generalizations reached in part 1 of the study for horizontal reference surfaces remain inviolate for sloping reference surfaces. However, significant additional information is brought out by reference to sloping surfaces. Further, differences in absolute radiation magnitudes are significant for realistic situations of cloudiness and shading when modelling short‐term (e.g. monthly) radiation means. In the annual case, these differences are small for glaciers having mean gradients up to 45°; for the one extremely steep glacier with mean slope approaching 60°, these differences are significant. It is anticipated that for higher latitudes the discrepancies between sloping and horizontal reference surfaces in the annual case may well be more substantial. For Mount Kenya, located as it is almost directly under the Equator, it must be concluded that the conventional horizontal reference surface is indeed appropriate for climatic heat and mass budget analyses.
Role of trabecular microarchitecture in the formation, accumulation, and morphology of microdamage in human cancellous bone
Authors: Karim Lamya , Vashishth Deepak
Published: April 2011

Alterations in microdamage morphology and accumulation are typically attributed to impaired remodeling, but may also result from changes in microdamage initiation and propagation. Such alterations are relevant for cancellous bone with high metabolic activity and numerous bone quality changes. This study investigates the role of trabecular microarchitecture on morphology and accumulation of microdamage in human cancellous bone. Trabecular bone cores from donors of varying ages and bone volume fraction (BV/TV) were separated into high and low BV/TV groups. Samples were subjected to no load or uniaxial compression to 0.6% (pre‐yield) or 1.1% (post‐yield) strain. Microdamage was stained with lead uranyl acetate and specimens were imaged via microcomputed tomography to quantify microdamage and determine its morphology in three‐dimensions (3D). Donors with high BV/TV had greater post‐yield strain and were tougher than low BV/TV donors. High BV/TV bone had less microdamage than low BV/TV bone under post‐ but not pre‐yield loading. Microdamage under both loading conditions showed significant correlations with microarchitecture and BV/TV, but the key predictor was structure model index (SMI). As SMI increased (more trabecular rods), microdamage morphology became crack‐like. Thus, low BV/TV and increased SMI have strong influences on microdamage accumulation in bone through altered initiation. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1739–1744, 2011