bluuebunny/crossref_metadata_2025 huggingface dataset:
Trace metal distributions within a Sitka eddy in the northern Gulf of Alaska
Authors: Brown Matthew T. , Lippiatt Sherry M. , Lohan Maeve C. , Bruland Kenneth W.
Published: March 2012

In the northern Gulf of Alaska, mesoscale, anticyclonic eddies have been implicated as a mechanism of the cross‐shelf exchange of iron (Fe)‐replete coastal waters with Fe‐deplete subarctic Alaskan gyre waters. Based on existing hydrography and macronutrient distributions, a Sitka eddy sampled during August 2007 is divided into a surface eddy core, a shallow subsurface eddy core, and a deeper subsurface eddy core. The distributions of aluminum (Al), manganese (Mn), and Fe in the eddy are examined and compared to distributions at shelf stations similar to where the eddy formed as well as basin stations representative of the Fe‐limited subarctic Alaskan gyre. Relative to basin stations, dissolved and particulate Al and dissolved Mn were elevated in eddy core waters. Reactive Fe concentrations within the shallow subsurface eddy core were nearly seven times greater than reactive Fe concentrations at similar densities at the basin stations. This shallow subsurface eddy core is likely mixed into the euphotic zone during storm‐induced mixing as well as mixing during isopycnal relaxation as an eddy dies out. The flux of reactive Fe to surface waters from the shallow subsurface core of eddies in the Gulf of Alaska is a significant source compared to both remote and local atmospheric dust deposition. It is hypothesized that Fe supply from eddies in the eastern Gulf of Alaska shifts the core of the high‐nutrient, lower‐than‐expected chlorophyll water farther west in conjunction with an “eddy desert” in that same region.
Factors controlling water‐column respiration in rivers of the central and southwestern Amazon Basin
Authors: Ellis Erin E. , Richey Jeffrey E. , Aufdenkampe Anthony K. , Krusche Alex V. , Quay Paul D. , Salimon Cleber , da Cunha Hilandia Brandão
Published: March 2012

We examined the factors controlling the variability in water‐column respiration rates in Amazonian rivers. Our objectives were to determine the relationship between respiration rates and the in situ concentrations of the size classes of organic carbon (OC), and the biological source (C3 and C4 plants and phytoplankton) of organic matter (OM) supporting respiration. Respiration was measured along with OC size fractions and dissolved oxygen isotopes (δ18O‐O2) in rivers of the central and southwestern Amazon Basin. Rates ranged from 0.034 µmol O2 L−1 h−1 to 1.78 µmol O2 L−1 h−1, and were four‐fold higher in rivers with evidence of photosynthetic production (demonstrated by δ18O‐O2 < 24.2‰) as compared to rivers lacking such evidence (δ18O‐O2 > 24.2‰; 1.35 ± 0.22 vs. 0.30 ± 0.29 µmol L−1 h−1). Rates were likely elevated in the former rivers, which were all sampled during low water, due to the stimulation of heterotrophic respiration via the supply of a labile, algal‐derived substrate and/or the occurrence of autotrophic respiration. The organic composition of fine particulate OM (FPOM) of these rivers is consistent with a phytoplankton origin. Multiple linear regression analysis indicates that [FPOC], C : NFPOC ratios, and [O2] account for a high amount of the variability in respiration rates (r2 = 0.80). Accordingly, FPOC derived from algal sources is associated with elevated respiration rates. The δ13C of respiration‐derived CO2 indicates that the role of phytoplankton, C3 plants, and C4 grasses in supporting respiration is temporally and spatially variable. Future scaling work is needed to evaluate the significance of phytoplankton production to basin‐wide carbon cycling.
Effects of CO2 and their modulation by light in the life‐cycle stages of the coccolithophore Emiliania huxleyi
Authors: Rokitta Sebastian D. , Rost Björn
Published: March 2012

The effects of ocean acidification on the life‐cycle stages of the coccolithophore Emiliania huxleyi and their modulation by light were examined. Calcifying diploid and noncalcifying haploid cells (Roscoff culture collection strains 1216 and 1217) were acclimated to present‐day and elevated CO2 partial pressures (PCO2; 38.5 vs. 101.3 Pa, i.e., 380 vs. 1000 µatm) under low and high light (50 vs. 300 µmol photons m−2 s−1). Growth rates as well as cellular quotas and production rates of C and N were measured. Sources of inorganic C for biomass buildup were determined using a 14C disequilibrium assay. Photosynthetic O2 evolution was measured as a function of dissolved inorganic C and light by means of membrane‐inlet mass spectrometry. The diploid stage responded to elevated PCO2 by shunting resources from the production of particulate inorganic C toward organic C yet keeping the production of total particulate C constant. As the effect of ocean acidification was stronger under low light, the diploid stage might be less affected by increased acidity when energy availability is high. The haploid stage maintained elemental composition and production rates under elevated PCO2. Although both life‐cycle stages involve different ways of dealing with elevated PCO2, the responses were generally modulated by energy availability, being typically most pronounced under low light. Additionally, PCO2 responses resembled those induced by high irradiances, indicating that ocean acidification affects the interplay between energy‐generating processes (photosynthetic light reactions) and processes competing for energy (biomass buildup and calcification). A conceptual model is put forward explaining why the magnitude of single responses is determined by energy availability.
Seasonal and interannual changes in water temperature affect the genetic structure of a Daphnia assemblage (D. longispina complex) through genotype‐specific thermal tolerances
Authors: Paul Rüdiger J. , Mertenskötter Ansgar , Pinkhaus Olaf , Pirow Ralph , Gigengack Ulrike , Buchen Ina , Koch Marita , Horn Wolfgang , Zeis Bettina
Published: March 2012

A field and laboratory study was carried out over 3 yr to determine relationships between seasonal and interannual changes in temperature (year‐specific temperature courses, presence or absence of ice in winter) and the genetic structure (composition of multilocus genotypes [MLGs]) of a Daphnia longispina assemblage. Field studies on temperature and genetic structures were linked with laboratory analyses to evaluate the thermal tolerance of long‐term 12°C‐, 18°C‐, and 24°C‐acclimated clonal lineages (CLs) derived from abundant MLGs sampled in the field (surface water and thermocline). The tolerance to warm temperatures (heat tolerance) was lowest in CLs derived from MLGs that were dominant directly after or before winter (winter‐CLs), higher in “spring‐autumn‐CLs,” and highest in “summer‐CLs.” Winter‐CLs also showed the highest degree of physiological plasticity. The differences in heat tolerance were mainly related to the different genotypes of the phosphoglucomutase (PGM) locus. Temperature conditions during winter and early spring affected the heat tolerance of all CLs as well as the success of different winter survival strategies (overwintering, resting eggs). Heat tolerance was lowest in CLs derived from MLGs sampled in 2006 (after the coldest winter and spring period), higher in CLs from 2005 (after a less cold winter and spring period), and highest in CLs from 2007 (after a warm, ice‐free winter). In addition to other environmental factors (predation, parasitism, food), seasonal and interannual changes in temperature affect Daphnia genetic structure through genetic differences in thermal responses, thermal tolerance, and physiological plasticity.
Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx
Authors: Saide P. E. , Spak S. N. , Carmichael G. R. , Mena-Carrasco M. A. , Yang Q. , Howell S. , Leon D. C. , Snider J. R. , Bandy A. R. , Collett J. L. , Benedict K. B. , de Szoeke S. P. , Hawkins L. N. , Allen G. , Crawford I. , Crosier J. , Springston S. R.
Published: March 2012

Abstract. We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and three aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign-averaged longitudinal gradients, and highlight differences in model simulations with (W) and without (NW) wet deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, especially in the activation parameterization, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions, and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, and may do so with the reliability required for policy analysis.
The historical pathway towards more accurate homogenisation
Authors: Domonkos P. , Venema V. , Auer I. , Mestre O. , Brunetti M.
Published: March 2012

Abstract. In recent years increasing effort has been devoted to objectively evaluate the efficiency of homogenisation methods for climate data; an important effort was the blind benchmarking performed in the COST Action HOME (ES0601). The statistical characteristics of the examined series have significant impact on the measured efficiencies, thus it is difficult to obtain an unambiguous picture of the efficiencies, relying only on numerical tests. In this study the historical methodological development with focus on the homogenisation of surface temperature observations is presented in order to view the progress from the side of the development of statistical tools. The main stages of this methodological progress, such as for instance the fitting optimal step-functions when the number of change-points is known (1972), cutting algorithm (1995), Caussinus – Lyazrhi criterion (1997), are recalled and their effects on the quality-improvement of homogenisation is briefly discussed. This analysis of the theoretical properties together with the recently published numerical results jointly indicate that, MASH, PRODIGE, ACMANT and USHCN are the best statistical tools for homogenising climatic time series, since they provide the reconstruction and preservation of true climatic variability in observational time series with the highest reliability. On the other hand, skilled homogenizers may achieve outstanding reliability also with the combination of simple statistical methods such as the Craddock-test and visual expert decisions. A few efficiency results of the COST HOME experiments are presented to demonstrate the performance of the best homogenisation methods.
Critical loads of nitrogen deposition and critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands
Authors: Pinho P. , Theobald M. R. , Dias T. , Tang Y. S. , Cruz C. , Martins-Loução M. A. , Máguas C. , Sutton M. , Branquinho C.
Published: March 2012

Abstract. Nitrogen (N) has emerged in recent years as a key factor associated with global changes, with impacts on biodiversity, ecosystems functioning and human health. In order to ameliorate the effects of excessive N, safety thresholds such as critical loads (deposition fluxes) and levels (concentrations) can be established. Few studies have assessed these thresholds for semi-natural Mediterranean ecosystems. Our objective was therefore to determine the critical loads of N deposition and long-term critical levels of atmospheric ammonia for semi-natural Mediterranean evergreen woodlands. We have considered changes in epiphytic lichen communities, one of the most sensitive comunity indicators of excessive N in the atmosphere. Based on a classification of lichen species according to their tolerance to N we grouped species into response functional groups, which we used as a tool to determine the critical loads and levels. This was done for a Mediterranean climate in evergreen cork-oak woodlands, based on the relation between lichen functional diversity and modelled N deposition for critical loads and measured annual atmospheric ammonia concentrations for critical levels, evaluated downwind from a reduced N source (a cattle barn). Modelling the highly significant relationship between lichen functional groups and annual atmospheric ammonia concentration showed the critical level to be below 1.9 μg m−3, in agreement with recent studies for other ecosystems. Modelling the highly significant relationship between lichen functional groups and N deposition showed that the critical load was lower than 26 kg (N) ha−1 yr−1, which is within the upper range established for other semi-natural ecosystems. Taking into account the high sensitivity of lichen communities to excessive N, these values should aid development of policies to protect Mediterranean woodlands from the initial effects of excessive N.
Carbon dynamics in the western Arctic Ocean: insights from full-depth carbon isotope profiles of DIC, DOC, and POC
Authors: Griffith D. R. , McNichol A. P. , Xu L. , McLaughlin F. A. , Macdonald R. W. , Brown K. A. , Eglinton T. I.
Published: March 2012

Abstract. Arctic warming is projected to continue throughout the coming century. Yet, our currently limited understanding of the Arctic Ocean carbon cycle hinders our ability to predict how changing conditions will affect local Arctic ecosystems, regional carbon budgets, and global climate. We present here the first set of concurrent, full-depth, dual-isotope profiles for dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), and suspended particulate organic carbon (POCsusp) at two sites in the Canada Basin of the Arctic Ocean. The carbon isotope composition of sinking and suspended POC in the Arctic contrasts strongly with open ocean Atlantic and Pacific sites, pointing to a combination of inputs to Arctic POCsusp at depth, including surface-derived organic carbon (OC), sorbed/advected OC, and OC derived from in situ DIC fixation. The latter process appears to be particularly important at intermediate depths, where mass balance calculations suggest that OC derived from in situ DIC fixation contributes up to 22% of POCsusp. As in other oceans, surface-derived OC is still a dominant source to Arctic POCsusp. Yet, we suggest that significantly smaller vertical POC fluxes in the Canada Basin make it possible to see evidence of DIC fixation in the POCsusp pool even at the bulk isotope level.
Organohalogen emissions from saline environments – spatial extrapolation using remote sensing as most promising tool
Authors: Kotte K. , Löw F. , Huber S. G. , Krause T. , Mulder I. , Schöler H. F.
Published: March 2012

Abstract. Due to their negative water budget most recent semi-/arid regions are characterized by vast evaporates (salt lakes and salty soils). We recently identified those hyper-saline environments as additional sources for a multitude of volatile halogenated organohalogens (VOX). These compounds can affect the ozone layer of the stratosphere and play a key role in the production of aerosols. A remote sensing based analysis was performed in the Southern Aral Sea basin, providing information of major soil types as well as their extent and spatial and temporal evolution. VOX production has been determined in dry and moist soil samples after 24 h. Several C1- and C2 organohalogens have been found in hyper-saline topsoil profiles, including CH3Cl, CH3Br, CHBr3 and CHCl3. The range of organohalogens also includes trans-1,2-dichloroethene (DCE), which is reported here to be produced naturally for the first time. Using MODIS time series and supervised image classification a daily production rate for DCE has been calculated for the 15 000 km2 ranging research area in the southern Aralkum. The applied laboratory setup simulates a short-term change in climatic conditions, starting from dried-out saline soil that is instantly humidified during rain events or flooding. It describes the general VOX production potential, but allows only for a rough estimation of resulting emission loads. VOX emissions are expected to increase in the future since the area of salt affected soils is expanding due to the regressing Aral Sea. Opportunities, limits and requirements of satellite based rapid change detection and salt classification are discussed.
A model-data comparison of the Holocene global sea surface temperature evolution
Authors: Lohmann G. , Pfeiffer M. , Laepple T. , Leduc G. , Kim J.-H.
Published: March 2012

Abstract. We compare the ocean temperature evolution of the Holocene as simulated by climate models and reconstructed from marine temperature proxies. We use transient simulations from a coupled atmosphere-ocean general circulation model, as well as an ensemble of time slice simulations from the Paleoclimate Modelling Intercomparison Project. The proxy dataset comprises a global compilation of marine alkenone- and Mg/Ca-derived sea surface temperature (SST) estimates. Independently of the choice of the climate model, we observe significant mismatches between modelled and estimated SST amplitudes in the trends for the last 6000 yr. Alkenone-based SST records show a similar pattern as the simulated annual mean SSTs, but the simulated SST trends underestimate the alkenone-based SST trends by a factor of two to five. For Mg/Ca, no significant relationship between model simulations and proxy reconstructions can be detected. We tested if such discrepancies can be caused by too simplistic interpretations of the proxy data. We therefore considered the additional environmental factor changes in the planktonic organisms' habitat depth and a time-shift in the recording season to diagnose whether invoking those environmental factors can help reconciling the proxy records and the model simulations. We find that invoking shifts in the living season and habitat depth can remove some of the model-data discrepancies in SST trends. Regardless whether such adjustments in the environmental parameters during the Holocene are realistic, they indicate that when modeled temperature trends are set up to allow drastic shifts in the ecological behavior of planktonic organisms, they do not capture the full range of reconstructed SST trends. These findings challenge the quantitative comparability of climate model sensitivity and reconstructed temperature trends from proxy data.
Inter-comparison of two land-surface models applied at different scales and their feedbacks while coupled with a regional climate model
Authors: Zabel F. , Mauser W. , Marke T. , Pfeiffer A. , Zängl G. , Wastl C.
Published: March 2012

Abstract. Downstream models are often used in order to study regional impacts of climate and climate change on the land surface. For this purpose, they are usually driven offline (i.e., 1-way) with results from regional climate models (RCMs). However, the offline approach does not allow for feedbacks between these models. Thereby, the land surface of the downstream model is usually completely different to the land surface which is used within the RCM. Thus, this study aims at investigating the inconsistencies that arise when driving a downstream model offline instead of interactively coupled with the RCM, due to different feedbacks from the use of different land surface models (LSM). Therefore, two physically based LSMs which developed from different disciplinary backgrounds are compared in our study: while the NOAH-LSM was developed for the use within RCMs, PROMET was originally developed to answer hydrological questions on the local to regional scale. Thereby, the models use different physical formulations on different spatial scales and different parameterizations of the same land surface processes that lead to inconsistencies when driving PROMET offline with RCM output. Processes that contribute to these inconsistencies are, as described in this study, net radiation due to land use related albedo and emissivity differences, the redistribution of this net radiation over sensible and latent heat, for example, due to different assumptions about land use impermeability or soil hydraulic reasons caused by different plant and soil parameterizations. As a result, simulated evapotranspiration, e.g., shows considerable differences of max. 280 mm yr−1. For a full interactive coupling (i.e., 2-way) between PROMET and the atmospheric part of the RCM, PROMET returns the land surface energy fluxes to the RCM and, thus, provides the lower boundary conditions for the RCM subsequently. Accordingly, the RCM responses to the replacement of the LSM with overall increased annual mean near surface air temperature (+1 K) and less annual precipitation (−56 mm) with different spatial and temporal behaviour. Finally, feedbacks can set up positive and negative effects on simulated evapotranspiration, resulting in a decrease of evapotranspiration South of the Alps a moderate increase North of the Alps. The inconsistencies are quantified and account for up to 30% from July to Semptember when focused to an area around Milan, Italy.
Delineating riparian zones for entire river networks using geomorphological criteria
Authors: Fernández D. , Barquín J. , Álvarez-Cabria M. , Peñas F. J.
Published: March 2012

Abstract. Riparian zone delineation is a central issue for riparian and river ecosystem management, however, criteria used to delineate them are still under debate. The area inundated by a 50-yr flood has been indicated as an optimal hydrological descriptor for riparian areas. This detailed hydrological information is, however, not usually available for entire river corridors, and is only available for populated areas at risk of flooding. One of the requirements for catchment planning is to establish the most appropriate location of zones to conserve or restore riparian buffer strips for whole river networks. This issue could be solved by using geomorphological criteria extracted from Digital Elevation Models. In this work we have explored the adjustment of surfaces developed under two different geomorphological criteria with respect to the flooded area covered by the 50-yr flood, in an attempt to rapidly delineate hydrologically-meaningful riparian zones for entire river networks. The first geomorphological criterion is based on the surface that intersects valley walls at a given number of bankfull depths above the channel (BFDAC), while the second is based on the surface defined by a~threshold value indicating the relative cost of moving from the stream up to the valley, accounting for slope and elevation change (path distance). As the relationship between local geomorphology and 50-yr flood has been suggested to be river-type dependant, we have performed our analyses distinguishing between three river types corresponding with three valley morphologies: open, shallow vee and deep vee valleys (in increasing degree of valley constrainment). Adjustment between the surfaces derived from geomorphological and hydrological criteria has been evaluated using two different methods: one based on exceeding areas (minimum exceeding score) and the other on the similarity among total area values. Both methods have pointed out the same surfaces when looking for those that best match with the 50-yr flood. Results have shown that the BFDAC approach obtains an adjustment slightly better than that of path distance. However, BFDAC requires bankfull depth regional regressions along the considered river network. Results have also confirmed that unconstrained valleys require lower threshold values than constrained valleys when deriving surfaces using geomorphological criteria. Moreover, this study provides: (i) guidance on the selection of the proper geomorphological criterion and associated threshold values, and (ii) an easy calibration framework to evaluate the adjustment with respect to hydrologically-meaningful surfaces.
MODIS snow cover mapping accuracy in small mountain catchment – comparison between open and forest sites
Authors: Parajka J. , Holko L. , Kostka Z. , Blöschl G.
Published: March 2012

Abstract. Numerous global and regional validation studies examined MODIS snow mapping accuracy by using measurements at climate stations, which are mainly at grassy sites. MODIS accuracy in alpine and forested regions is, however, still not well understood. The main objective of this study is to evaluate MODIS (MOD10A1 and MYD10A1) snow cover products in a small experimental catchment by using extensive snow course measurements at open and forest sites. The MODIS accuracy is tested in the Jalovecky creek catchment (Northern Slovakia) in the period 2000–2011. The results show that the combined Terra and Aqua images enables snow mapping to an overall accuracy of 91.5%. The accuracy at forested, open and mixed land uses at the Červenec sites is 92.7%, 98.3% and 81.8%, respectively. The use of a 2-day temporal filter enables a significant reduction in the number of days with cloud coverage and an increase in overall snow mapping accuracy. In total, the 2-day temporal filter decreases the number of cloudy days from 61% to 26% and increases the snow mapping accuracy to 94%. The results indicate three possible factors leading to misclassification of snow as land: patchy snow cover, limited MODIS geolocation accuracy and mapping algorithm errors. Out of a total of 27 misclassification cases, patchy snow cover, geolocation issues and mapping errors occur in 12, 12 and 3 cases, respectively.
Modelling catchment-scale shallow landslide occurrence by means of a subsurface flow path connectivity index
Authors: Lanni C. , Borga M. , Rigon R. , Tarolli P.
Published: March 2012

Abstract. Topographic index-based hydrological models have gained wide use to describe the hydrological control on the triggering of rainfall-induced shallow landslides at the catchment scale. A common assumption in these models is that a spatially continuous water table occurs simultaneously at any point across the catchment. However, during a rainfall event isolated patches of subsurface saturation form above an impeding layer and hydrological connectivity of these patches is a necessary condition for lateral flow initiation at a point on the hillslope. Here, a new hydrological model is presented, which allows to account for the concept of hydrological connectivity while keeping the simplicity of the topographic index approach. A dynamic topographic index is used to describe the transient lateral flow that is established at a hillslope element when the rainfall amount exceeds a threshold value allowing for (a) development of a perched water table above an impeding layer, (b) hydrological connectivity between the hillslope element and its own upslope contributing area. A spatially variable soil depth is the main control of hydrological connectivity in the model. The hydrological model is coupled with the infinite slope stability model, and with a scaling model for the rainfall frequency-duration relationship to determine the return period of the critical rainfall needed to cause instability on three catchments located in the Italian Alps. The results show the good ability of our model in predicting observed shallow landslides. The model is finally used to determine local rainfall intensity-duration thresholds that may lead to shallow landslide initiation.
Coupling the modified SCS-CN and RUSLE models to simulate hydrological effects of restoring vegetation in the Loess Plateau of China
Authors: Gao G. Y. , Fu B. J. , Lü Y. H. , Liu Y. , Wang S. , Zhou J.
Published: March 2012

Abstract. Predicting event runoff and soil loss under different land covers is essential to quantitatively evaluate the hydrological responses of vegetation restoration in the Loess Plateau of China. The Soil Conservation Service Curve Number (SCS-CN) and Revised Universal Soil Loss Equation (RUSLE) models are widely used in this region to this end. This study incorporated antecedent moisture condition (AMC) in runoff production and initial abstraction of the SCS-CN model, and considered the direct effect of runoff on event soil loss by adopting a rainfall-runoff erosivity factor in the RUSLE model. The modified SCS-CN and RUSLE models were coupled to link rainfall-runoff-erosion modeling. The effects of AMC, slope gradient and initial abstraction ratio on curve number of SCS-CN, as well as those of vegetation cover on cover-management factor of RUSLE were also considered. Three runoff plot groups covered by sparse young trees, native shrubs and dense tussock, respectively, were established in the Yangjuangou catchment of Loess Plateau. Rainfall, runoff and soil loss were monitored during the rainy season in 2008–2011 to test the applicability of the proposed approach. The original SCS-CN model significantly underestimated the event runoff, especially for the rainfall events that have large 5-day antecedent precipitation, whereas the modified SCS-CN model could predict event runoff well with Nash-Sutcliffe model efficiency (EF) over 0.85. The original RUSLE model overestimated low values of measured soil loss and under-predicted the high values with EF only about 0.30. In contrast to it, the prediction accuracy of the modified RUSLE model improved satisfactorily with EF over 0.70. Our results indicated that the AMC should be explicitly incorporated in runoff production, and direct consideration of runoff should be included in predicting event soil loss. Coupling the modified SCS-CN and RUSLE models appeared to be appropriate for runoff and soil loss simulation at plot scale in the Loess Plateau. The limitations and future study scopes of the proposed models were also indicated.
Influence of Ethnicity on Health-Related Quality of Life of Hemodialysis Patients in Singapore
Authors: Wang Vivian , Seow Ying-ying , Leng Chow Wai
Published: March 2012

Objectives

The association between health-related quality of life (HRQoL) and ethnicity has been studied among hemodialysis (HD) patients in several countries with varying results. However, the effect of ethnicity on the HRQoL of HD patients in the Asian context has yet to be evaluated. This study seeks to examine the HRQoL of HD patients in Singapore and to understand the influence of ethnicity on their HRQoL.

Methods

A census-style survey inclusive of the KDQoL-SF. The AMA was conducted among all HD patients from 22 dialysis centers across Singapore. Multiple linear regression models were used to analyze the influence of ethnicity on each SF-36 scale while adjusting for the influence of socioeconomic status (SES) factors and other determinants of HRQoL.

Results

Data from 1,249 HD patients were analyzed. Response rate was 63.3%. Compared with other ethnicities, Chinese were most likely to report lower HRQoL. After adjusting for sex, age, and other possible determinants of HRQoL, the influence of ethnicity on HRQoL persisted, with significant mean differences in role-physical, general health, role-emotional, and physical component summary scales.

Conclusions

After adjusting for demographic, SES, and other factors, ethnicity remained an important factor influencing HRQoL of Singaporean HD patients. Further studies are needed to identify modifiable factors that might explain the interethnic differences in HRQoL among HD patients.
Comparative Role of PET and Kt/V Determination in Pediatric Chronic Peritoneal Dialysis
Authors: Watanabe Andreia , Lanzarini Vivian V. , Filho Ulisses D. , Koch Vera H.
Published: March 2012

Introduction

Nutritional state and growth are considered as prognostic markers of chronic peritoneal dialysis (PD) adequacy in pediatric patients. The euvolemia, blood pressure control, and metabolic and electrolytic equilibrium are parameters to be achieved by PD treatment.

Objective

To describe the chronic PD prescription parameters of a cohort of pediatric patients and to compare the obtained hemodynamic, antrophometric and adequacy results with those suggested by the literature.

Methods

Retrospective analysis based on clinical records evaluation of 30 pediatric patients undergoing PD for more than 6 months from January 1998 to May 2005.

Results

In the present study, 17/30 (56.7%) were boys. Chronic kidney disease was secondary to uropathy in 66.7% of the cases. The infusion volume was > 1,000 ml/m2 in 9 patients. The peritoneal membrane was characterized as high (27.8%), high-average (33.3%), low-average (22.2%) and low transporter (16.7%). The weekly urea Kt/V was > 2.1 in all the evaluated patients. Blood pressure parameters above the 95th percentile despite the use of antihypertensive medication were observed in 5/30 patients, four of whom with CKD secondary to glomerulopathy. The initial and final Body Mass Index and weight for height ratio were preserved in 83.3% (25/30) patients.

Conclusion

Elevated indexes of small solutes removal are easily attained in pediatric PD patients and do not imply optimal clinical management do not imply optimal climanagement.
Stem Cell Banking: Ethical and Policy Issues
Authors: King Nancy
Published: March 2012

Much stem cell research and many stem cell-based interventions depend on the availability of numerous viable cell lines. Multipotent and pluripotent stem cell lines may be created from embryonic stem cells, but also from stem cells found in amniotic fluid, umbilical cord blood, and other non-embryonic sources. Stem cell banks could collect, store and share enough cell lines to make good HLA matches with the vast majority of the inhabitants of a country or region, and thus might be easier and less expensive to use widely than individually matched induced pluripotent stem cell lines.

The collection, storage and sharing of stem cells in and through biobanks raises a well-known set of interesting ethical and policy issues for stakeholders: the individuals who provide their stem cells for banking, the biobanks that collect and store them, the investigators who use them for many types of research, and the patient-subjects who receive them in research studies or innovative interventions.

This presentation explores these ethical and policy issues, which include: informed consent, confidentiality and recontact, ownership and benefit-sharing, scope and control of future uses, innovation and the therapeutic misconception, and considerations of justice.
Mechanisms of Mesoderm Differentiation in Pluripotent Mammalian Stem Cells
Authors: Pedersen Roger
Published: March 2012

Our research focuses on understanding how pluripotent mammalian stem cells maintain their undifferentiated state and undergo differentiation in culture – this reflecting my enduring interest in the emergence of diversity during mouse gastrulation.

In recent studies we have examined the role of transforming growth factor family members in both pluripotency and differentiation. This involved analysis of the signalling cascade induced by treating hESCs with Activin or Nodal, determining how their response to these growth factors maintains hESC pluripotency. We started by developing chemically defined culture conditions in which the activities of specific growth factors could be identified and studied in a controlled manner. We then carried out a detailed analysis of the roles of Smad proteins (Smad2 and Smad3) as direct regulators of Nanog, which in turn blocks an hESC default differentiation into neuroectoderm. These studies led to our discovery of a novel type of pluripotent epiblast stem cell (EpiSC) from the late epiblast layer of mouse and rat embryos. EpiSCs share many features with hESCs, and subsequent work supports our hypothesis that hESCs are the human counterparts of EpiSCs, with similar responses to growth factors and mechanisms of pluripotency and differentiation.

In our most recent work we have focused on the role of bone morphogenetic protein (BMP)-4 in the cell fate decision between endoderm and mesoderm, demonstrating the similarity of BMP-induced hESC and EpiSC differentiation to mesoderm induction during mouse gastrulation. This work reveals the importance of BRACHYURY and CDX2 genes as key mediators of embryonic and extraembryonic lineage differentiation in hESCs and EpiSCs. Our focus on mesoderm leads us on to molecular pathways for early human cardiomyocyte differentiation, with a goal of understanding the transcriptional networks responsible for cardiomyocyte identity and using this to generate more homogeneous cardiomyocyte populations for therapeutic applications and drug discovery. Taken together, these studies should significantly accelerate the progression from basic stem cell research to clinical applications.
Environmental Exposure and Nonadherence with Medicines Directly Correlate with Exacerbations and Hospitalization for Asthma: A Population-Based Survey from UAE
Authors: Mahboub Bassam , Vats Mayank , Afzal Shahid , Sharif Walid , Iqbal Mohammed Nizam
Published: March 2012

Acute severe exacerbation of asthma is directly related with the uncontrolled asthma including noncompliance with the medicines and exposure to the environmental factors. To our knowledge, none of the community-based study has explored the prevalence of asthma and other factors (namely, pattern of symptoms, environmental/occupational/housing/behavioral pattern/misperception about asthma, and educational factors) contributing to the exacerbation of asthma. We also studied the nonadherence issues related to the management of asthma in the United Arab Emirates (UAE). By using European Community Respiratory Health Survey (ECRHS) questionnaires and pooled data from AIRGNE (UAE) study, we aimed to determine the above-mentioned factors in the general population by means of a cross-sectional assessment of a random sample of 1,229 participants of which 62.97% were male and 20.01% were UAE nationals, with a mean age (±SD) of 32.9 (±14.1) years. Prevalence of individual respiratory symptoms from the ECRHS questionnaire in all participants ranged from 8 to 10%, while those participants aged 20–44 years presented a lower prevalence in all symptoms (P<0.05). Conclusion. Certain specific persistent environmental factor along with nonadherence to the controller medicines is a significant factor leading to uncontrolled asthma with consequent exacerbations, morbidity/mortality, and health care cost in UAE.
Equations of bark thickness and volume profiles at different heights with easy-measurement variables
Authors: Cellini J.M. , Galarza M. , Burns S.L. , Martinez-Pastur G.J. , Lencinas M.V.
Published: March 2012

The objective of this work was to develop equations of thickness profile and bark volume at different heights with easy-measurement variables, taking as a study case Nothofagus pumilio forests, growing in different site qualities and growth phases in Southern Patagonia. Data was collected from 717 harvested trees. Three models were fitted using multiple, non-lineal regression and generalized linear model, by stepwise methodology, iteratively reweighted least squares method for maximum likelihood estimation and Marquardt algorithm. The dependent variables were diameter at 1.30 m height (DBH), relative height (RH) and growth phase (GP). The statistic evaluation was made through the adjusted determinant coefficient (r2-adj), standard error of the estimation (SEE), mean absolute error and residual analysis. All models presented good fitness with a significant correlation with the growth phase. A decrease in the thickness was observed when the relative height increase. Moreover, a bark coefficient was made to calculate volume with and without bark of individual trees, where significant differences according to site quality of the stands and DBH class of the trees were observed. It can be concluded that the prediction of bark thickness and bark coefficient is possible using DBH, height, site quality and growth phase, common and easy measurement variables used in forest inventories.
Edible wild mushroom tourism as a source of income and employment in rural areas. The case of Castilla y León
Authors: De Frutos Madrazo P. , Martínez-Peña F. , Esteban S.
Published: March 2012

Edible wild mushroom picking is becoming an important source of income in rural areas. The wide range of activitieswhich add value to mycological production (initial sale, transformation, marketing, etc.) include those related to tourismwhich can attract visitors to mushroom producing areas, leading to so-called mycological tourism. To date, no researchexists quantifying the importance thereof in rural areas endowed with such resources. The present research provides thefirst model to estimate this activity’s contribution to the economy of rural areas in the region of Castilla y León. The mainfinding to emerge evidences a close link between influx of visitors, who come principally to pick, and mycological productivityin the region. Based on this relation, we estimate four key variables to determine the impact which said activityhas on the regional economy as a whole: the number of overnight stays and trips made by mycological tourists, as wellas associated expenditure and employment created. Findings underscore the importance of this activity in the regionaltourism industry and point to its significance as a major market niche, particularly during the hotel low season. The needfor public administrators to implement a related management policy is also inferred.
Adaptability to climate change in forestry species: drought effects on growth and wood anatomy of ponderosa pines growing at different competition levels
Authors: Fernández M.E. , Gyenge J.E. , De Urquiza M.M. , Varela S.
Published: March 2012

More stressful conditions are expected due to climatic change in several regions, including Patagonia, South-America. In this region, there are no studies about the impact of severe drought events on growth and wood characteristics of the most planted forestry species, Pinus ponderosa (Doug. ex-Laws). The objective of this study was to quantify the effect of a severe drought event on annual stem growth and functional wood anatomy of pines growing at different plantation densities aiming to understand how management practices can help to increase their adaptability to climate change. Growth magnitude and period, specific hydraulic conductivity, and anatomical traits (early- and latewood proportion, lumen diameter, cell-wall thickness, tracheid length and bordered pit dimensions) were measured in the ring 2008-2009, which was formed during drought conditions. This drought event decreased annual stem growth by 30-38% and 58-65% respect to previous mean growth, in open vs. closed stand trees, respectively, indicating a higher sensitivity of the latter, which is opposite to reports from the same species growing in managed native forests in USA. Some wood anatomical variables did differ in more water stressed trees (lower cell wall thickness of early wood cells and higher proportion of small-lumen cells in latewood), which in turn did not affect wood function (hydraulic conductivity and resistance to implosion). Other anatomical variables (tracheid length, pit dimensions, early- and latewood proportion, lumen diameter of early wood cells) did not differ between tree sizes and plantation density. The results suggest that severe drought affects differentially the amount but not the function and quality of formed wood in ponderosa pine growing at different competition levels.
Reporting Research for Practitioners: Proposed Guidelines
Authors: Heck Daniel J. , Tarr James E. , Hollebrands Karen F. , Walker Erica N. , Berry III Robert Q. , Baltzley Patricia C. , Rasmussen Chris L. , King Karen D.
Published: March 2012

The National Council of Teachers of Mathematics (NCTM) espouses priorities to foster stronger linkages between mathematics education research and teaching practice. Of the five foundational priorities, one is directly focused on research, indicating NCTM's commitment to “ensure that sound research is integrated into all activities of the Council” (NCTM, n.d.). Another priority specifically references the relationship between research and mathematics teaching; the priority on curriculum, instruction, and assessment states that NCTM pledges to “Provide guidance and resources for developing and implementing mathematics curriculum, instruction, and assessment that are coherent, focused, well-articulated, and consistent with research in the field [emphasis added], and focused on increasing student learning” (NCTM, n.d.).
Effects of a Teacher Professional Development Program on the Mathematics Achievement of Middle School Students
Authors: McMeeking Laura B. Sample , Orsi Rebecca , Cobb R. Brian
Published: March 2012

The effect of a 15- to 24-month in-service professional development (PD) program on state accountability mathematics test scores for middle school students was examined using a quasi-experimental design. Middle level mathematics teachers (n = 128) from 7 school districts and 64 middle schools volunteered for a PD sequence of content-oriented summer courses and pedagogy-oriented structured follow-up experiences during the subsequent academic year. Student effects of the PD program were measured using Colorado's state mathematics test results for 2 cohorts of students: 1 that received mathematics instruction from participant teachers in the year prior to the PD and another cohort that received mathematics instruction in the year following the PD. The odds of a student achieving a Proficient or Advanced score on the state test were then compared between cohorts. Results showed that students' odds of achieving a score of Proficient or better increased with teacher participation in the PD program.
On the Connections Between General Education Theories and Theories in Mathematics Education
Authors: Leikin Roza , Zazkis Rina
Published: March 2012

This book review explores Theories of Mathematics Education: Seeking New Frontiers, edited by Bharath Sriraman and Lyn English.
Straightforward Synthesis of Allylated Keto Esters: The Palladium‐Catalysed Haloketone Alkoxycarbonylation/ Allylation Domino Reaction
Authors: Wahl Benoit , Giboulot Steven , Mortreux André , Castanet Yves , Sauthier Mathieu , Liron Frédéric , Poli Giovanni
Published: March 2012

The palladium‐catalysed α‐chloro ketone methoxycarbonylation and allylic alkylation reactions can be efficiently combined to provide a new catalytic domino reaction. The first, carbonylative, step generates the β‐keto ester, which acts as the nucleophile in a subsequent allylation step. The use of allyl phenates in combination with Xantphos ligand are the key features allowing one to obtain the allylated β‐keto esters in good yields
The Effect of Attitudinal and Sociodemographic Factors on the Likelihood of Buying Locally Produced Food
Authors: Cranfield John , Henson Spencer , Blandon Jose
Published: March 2012

This study explores the factors associated with Canadian consumers locally produced food purchase intention. Data from an Internet‐based survey of consumers (n = 1,139) was analyzed using a bivariate probit model. The bivariate probit model related attitudinal, behavioral and sociodemographic factors to the intention to purchase fresh and nonfresh locally produced foods. Although sociodemographic characteristics play a limited role in shaping local food purchase intentions, attitudinally based variables have far greater influence. Positive views towards local farmers and agriculture in general, as well as food quality, are positively related to purchase intention. The importance placed on brand‐specific quality is inversely related to the intention to buy local food. Consumers with heightened levels of food involvement, either growing food or preparing most meals from scratch, are more likely to purchase local foods. (EconLit Citations: L660; Q130; Q180)