bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ground‐ and satellite‐based evidence of the biophysical mechanisms behind the greening Sahel
Authors: Brandt Martin , Mbow Cheikh , Diouf Abdoul A. , Verger Aleixandre , Samimi Cyrus , Fensholt Rasmus 
Published: November 2014

AbstractAfter a dry period with prolonged droughts in the 1970s and 1980s, recent scientific outcome suggests that the decades of abnormally dry conditions in the Sahel have been reversed by positive anomalies in rainfall. Various remote sensing studies observed a positive trend in vegetation greenness over the last decades which is known as the re‐greening of the Sahel. However, little investment has been made in including long‐term ground‐based data collections to evaluate and better understand the biophysical mechanisms behind these findings. Thus, deductions on a possible increment in biomass remain speculative. Our aim is to bridge these gaps and give specifics on the biophysical background factors of the re‐greening Sahel. Therefore, a trend analysis was applied on long time series (1987–2013) of satellite‐based vegetation and rainfall data, as well as on ground‐observations of leaf biomass of woody species, herb biomass, and woody species abundance in different ecosystems located in the Sahel zone of Senegal. We found that the positive trend observed in satellite vegetation time series (+36%) is caused by an increment of in situ measured biomass (+34%), which is highly controlled by precipitation (+40%). Whereas herb biomass shows large inter‐annual fluctuations rather than a clear trend, leaf biomass of woody species has doubled within 27 years (+103%). This increase in woody biomass did not reflect on biodiversity with 11 of 16 woody species declining in abundance over the period. We conclude that the observed greening in the Senegalese Sahel is primarily related to an increasing tree cover that caused satellite‐driven vegetation indices to increase with rainfall reversal.
Effects of larval density and food stress on life‐history traits of Cnaphalocrocis medinalis (Lepidoptera: Pyralidae)
Authors: Yang F. , Hu G. , Shi J. J. , Zhai B. P. 
Published: November 2014

AbstractHigh population density and nutrition restriction can lead to phase variation in morphology and development, and subsequently induce changes in the reaction norms of adult flight in migrant insects. However, response of migratory propensity to such stress in Endopterygote insects, especially in several species of Lepidoptera, remains unclear. In this study, larval and adult developmental responses to crowding and food stress were investigated in the migratory moth, Cnaphalocrocis medinalis (Guenée). A high larval rearing density significantly reduced pupal mass, survival rate and female fecundity. Larvae developed rapidly under crowding conditions, and time to pupation was 2 days earlier than individuals reared alone. By contrast, short‐term starvation and associated compensatory growth prolonged larval duration by 3–4 days and pupal duration by 1–2 days. It also reduced the pupal mass, but showed no detectable effects on female reproductive performance. Both sexes had similar development strategies; however, females seemed to be more sensitive to crowding and food shortage than males. A positive effect was expected if such stress factors acted as cues that triggering a behavioural or physiological shift to a distinct migratory phase. To the contrary, we found no proof that crowding and starvation caused maturation delay in female reproductive development. All treatments did not significantly increase female pre‐oviposition period. Therefore, we concluded that life developmental responses to crowding and food shortage in this species were different. Adult migration propensity was not enhanced under such stress conditions during the larval phase.
Compositional decoupling of savanna canopy and understory tree communities in Serengeti
Authors: Anderson T. Michael , Morrison Thomas , Rugemalila Deusdedith , Holdo Ricardo 
Published: November 2014

AbstractQuestionsWhat is the pattern of compositional similarity for woody plants across the demographic bottleneck (i.e. canopy trees >2 m vs understorey trees <2 m) commonly observed in savannas? Does compositional similarity between woody plants in the canopy and understorey change across environmental gradients, and if so, which resource or disturbance factors explain the pattern? Finally, does disturbance history, i.e. whether individuals are newly established seedlings or top‐killed resprouts, help to explain the compositional similarity between canopy and understorey woody plants across sites?LocationThe Serengeti ecosystem, Tanzania, East Africa.MethodsWe compared the observed similarity to that expected from a simulated null model, and investigated the association between compositional similarity and soil bulk density, mean annual rainfall, fire return interval and elephant damage using a model selection approach. Moreover, we asked if disturbance history, i.e. whether individuals were newly established seedlings or top‐killed resprouts, helped explain compositional similarity between the canopy and understorey.ResultsThe composition of canopy (>2 m) and understorey (<2 m) trees was surprisingly distinct: Acacia robusta (37.9%) and Acacia tortilis (23.7%) dominated the canopy, while Ormocarpum trichocarpum (43.0%) and Dichrostachys cinerea (19.6%) dominated the understorey. Compositional similarity between canopy and understorey woody plants generally decreased with soil bulk density, while for top‐killed individuals there was support for an increase in compositional similarity with fire return interval.ConclusionsOur results suggest that the similarity between the canopy and recruitment communities is primarily associated with soil factors. Our results also suggest that long fire return intervals (i.e. infrequent fires) lead to increased similarity between the composition of the canopy and the recruitment pool, suggesting that disturbance promotes heterogeneity in the community across demographic bottlenecks. Despite the prominent role that megaherbivores and disturbance play in driving structural changes in savannas, our results suggest that previously unreported but pervasive species decoupling across demographic bottlenecks is primarily driven by resource availability or other bottom‐up constraints.
Genome‐wide scans of genetic variants for psychophysiological endophenotypes: A methodological overview
Authors: Iacono William. G. , Malone Stephen. M. , Vaidyanathan Uma , Vrieze Scott I. 
Published: November 2014

AbstractThis article provides an introductory overview of the investigative strategy employed to evaluate the genetic basis of 17 endophenotypes examined as part of a 20‐year data collection effort from the Minnesota Center for Twin and Family Research. Included are characterization of the study samples, descriptive statistics for key properties of the psychophysiological measures, and rationale behind the steps taken in the molecular genetic study design. The statistical approach included (a) biometric analysis of twin and family data, (b) heritability analysis using 527,829 single nucleotide polymorphisms (SNPs), (c) genome‐wide association analysis of these SNPs and 17,601 autosomal genes, (d) follow‐up analyses of candidate SNPs and genes hypothesized to have an association with each endophenotype, (e) rare variant analysis of nonsynonymous SNPs in the exome, and (f) whole genome sequencing association analysis using 27 million genetic variants. These methods were used in the accompanying empirical articles comprising this special issue, Genome‐Wide Scans of Genetic Variants for Psychophysiological Endophenotypes.
Heritability and molecular genetic basis of acoustic startle eye blink and affectively modulated startle response: A genome‐wide association study
Authors: Vaidyanathan Uma , Malone Stephen M. , Miller Michael B. , McGue Matt , Iacono William G. 
Published: November 2014

AbstractAcoustic startle responses have been studied extensively in relation to individual differences and psychopathology. We examined three indices of the blink response in a picture‐viewing paradigm—overall startle magnitude across all picture types, and aversive and pleasant modulation scores—in 3,323 twins and parents. Biometric models and molecular genetic analyses showed that half the variance in overall startle was due to additive genetic effects. No single nucleotide polymorphism was genome‐wide significant, but GRIK3 produced a significant effect when examined as part of a candidate gene set. In contrast, emotion modulation scores showed little evidence of heritability in either biometric or molecular genetic analyses. However, in a genome‐wide scan, PARP14 produced a significant effect for aversive modulation. We conclude that, although overall startle retains potential as an endophenotype, emotion‐modulated startle does not.
Genomic substrates of neurophysiological endophenotypes: Where we've been and where we're going
Authors: Braff David L. 
Published: November 2014

AbstractThis special issue of Psychophysiology is focused on an imaginative and labor‐intensive examination of the genomic substrates of heritable neurophysiological endophenotypes in the Minnesota Center for Twin and Family Research (MCTFR) cohorts. The authors artfully combine the power of family‐based behavioral data with the atheoretical genome‐wide association study (GWAS) platform to enrich the examination of the genomic substrates of endophenotypes. Neurophysiological endophenotype deficits are found in psychiatric patients and are heritable in families of these psychiatric patients, allowing the investigators to combine the explanatory power of endophenotypes, with their known neural and functional substrates, with the otherwise agnostic identification of genes in the GWAS platform. This amplifies the power of the MCTFR endophenotype database. These well‐considered studies add significantly to our understanding of normal human neurobiology and stimulate the use of these endophenotypes to expand our knowledge of the role of these measures and their genomic substrates in normal and psychopathology research.
Activation of Ca2+‐activated Cl− channel ANO1 by localized Ca2+ signals
Authors: Jin Xin , Shah Sihab , Du Xiaona , Zhang Hailin , Gamper Nikita 
Published: November 2014

AbstractCa2+‐activated chloride channels (CaCCs) regulate numerous physiological processes including epithelial transport, smooth muscle contraction and sensory processing. Anoctamin‐1 (ANO1, TMEM16A) is a principal CaCC subunit in many cell types, yet our understanding of the mechanisms of ANO1 activation and regulation are only beginning to emerge. Ca2+ sensitivity of ANO1 is rather low and at negative membrane potentials the channel requires several micromoles of intracellular Ca2+ for activation. However, global Ca2+ levels in cells rarely reach such levels and, therefore, there must be mechanisms that focus intracellular Ca2+ transients towards the ANO1 channels. Recent findings indeed indicate that ANO1 channels often co‐localize with sources of intracellular Ca2+ signals. Interestingly, it appears that in many cell types ANO1 is particularly tightly coupled to the Ca2+ release sites of the intracellular Ca2+ stores. Such preferential coupling may represent a general mechanism of ANO1 activation in native tissues.
Investigation of ATHLET System Code for Supercritical Water Applications
Authors: Samuel J. , Lerchl G. , Harvel G. D. , Pioro I. 
Published: November 2014

SuperCritical Water-cooled Reactors (SCWRs) are one of six Generation-IV nuclear-reactor concepts. They are expected to have high thermal efficiencies within the range of 45–50% owing to the reactor’s high pressures and outlet temperatures. Efforts have been made to study the supercritical phenomena both analytically and experimentally. However, codes that have been used to study the phenomena analytically have not been validated for supercritical water.
The thermal-hydraulic computer code ATHLET (Analysis of THermal-hydraulics of LEaks and Transients) is used for analysis of anticipated and abnormal plant transients, including safety analysis of Light Water Reactors (LWRs) and Russian Graphite-Moderated High Power Channel-type Reactors (RBMKs). The range of applicability of ATHLET has been extended to supercritical water by updating the fluid- and transport-properties packages, thus enabling a transition from subcritical to supercritical fluid states. This extension needs to be validated using experimental data.
In this work, the applicability of ATHLET code to predict supercritical-water behaviour in various heat-transfer conditions is assessed. Several well-known heat-transfer correlations for supercritical fluids are added to the code and applied for the first time in ATHLET simulations of experiments. A numerical model in ATHLET is created to represent an experimental test section and results for the heat transfer coefficient, bulk fluid temperature, and the tube inside-wall temperature are compared with the experimental data.
The results from the ATHLET simulations are promising in the Normal and Enhanced Heat-Transfer Regimes. However, important phenomena such as Deteriorated Heat Transfer are currently not accurately predicted. While ATHLET can be used to develop preliminary design solutions for SCWRs, a significant effort in analysis of experimental work is required to make further advancements in the use of ATHLET for SCW applications.
Assessment Oxidation Kinetics and Products in SCWR Media of Austenitic ODS Steels With Different Austenite Stabilisers
Authors: Mihalache Maria , Mihalache Mihail , Dumitrescu Iulia , Zhou Zhangjian 
Published: November 2014

In order to fulfil requirements for corrosion resistance for new reactor GIV, the austenitic 304L stainless steel and 18Cr-20Mn austenitic steel were improved by oxide dispersion strengthening (ODS), using two nano-oxide types: titanium and yttrium oxides.
Two new ODS steels and a reference material, A/SA-270 grade 304L SS as plate, were characterised by different techniques and its behaviour in SCWR environment was considered. Coolant compatibility studies have been performed in demineralised water at supercritical conditions: temperature of about 550°C and 25 MPa pressure. The oxide developed on the 304ODS samples is layered, thicker and more uniform than on 304L SS. Some oxides grown on 18Cr-20MnODS steel are un-adherently and they are lost in the simulated water coolant.
The weight gains of ODS samples are positive and higher than 304L SS up to approximately 1320 hours while on 18Cr-20MnODS steel is negative. The oxide films were investigated by SEM and EDS techniques.
Comparison of Nuclear Fitness for Service Codes: ASME Section XI and RSE-M AFCEN Codes
Authors: Faidy Claude 
Published: November 2014

Two major Codes are used for Fitness for Service of Nuclear Power Plants: one is the ASME B&PV Code Section XI and the other one is the French RSE-M Code. Both of them are largely used in many countries, partially or totally.
The last 2013 RSE-M covers “Mechanical Components of Pressurized Water Reactors (PWRs):
- Pre-service and In-service inspection
- Surveillance in operation or during shutdown
- Flaw evaluation
- Repairs-Replacements parts for plant in operation
- Pressure tests
The last 2013 ASME Section XI covers “Mechanical components and containment of Light Water Reactors (LWRs)” and has a larger scope with similar topics: more types of plants (PWR and Boiling Water Reactor-BWR), other components like metallic and concrete containments…
The paper is a first comparison covering the scope, the jurisdiction, the general organization of each section, the major principles to develop In Service Inspection, Repair-Replacement activities, the flaw evaluation rules, the pressure test requirements, the surveillance procedures (monitoring…) and the connections with Design Codes…
These Codes are extremely important for In-service inspection programs in particular and essential tools to justify long term operation of Nuclear Power Plants.
Fatigue Design Rules in Pressure Vessel Codes Uncertainties and Remaining Open Points
Authors: Faidy Claude 
Published: November 2014

During the past 30 years the main rules for fatigue analysis of pressure vessels were based on elastic approaches in order to evaluate a cyclic strain amplitude and compare with an S-N fatigue curve for the corresponding material. After review of some rules in different Nuclear and Non Nuclear Codes, like ASME Boiler & Pressure Vessel Code Section III, French RCC-M and RCC-MRx, European Standards EN 13445, the major conservatisms and uncertainties of different rules are discussed.
All these Codes propose simple rules to evaluate the strain amplitude based on elastic approaches and simplified correction factors (Ke and Kv), transient combination rules and damage cumulating procedure.
In the other hand, the material properties are based on standard fatigue tests done on the material associated to reduction factors to consider some particular effects like scatter, scale, surface roughness, mean stress or environmental effects to transfer them from small specimen to real structures.
Concerned components are mainly piping systems.
No existing Code covers all the aspects of fatigue with similar conservatisms that can affect the in-service inspection programs and the remaining life assessment of the corresponding components.
After the review of different rules, key factors that affect the results and predictions will be identified.
Some proposals will be issued to progress in the near future. Finally, a first set of recommendation on fatigue analysis will be presented to improve existing codes on an harmonized way, associated to material properties needed, as fatigue curves associated to reduction factors.
Two-Way Coupling Between the Reactor Dynamics Code DYN3D and the Fuel Performance Code TRANSURANUS at Assembly Level
Authors: Holt L. , Rohde U. , Seidl M. , Schubert A. , Van Uffelen P. , Macián-Juan R. 
Published: November 2014

In the last two decades the reactor dynamics code DYN3D was coupled to thermal hydraulics system codes, a sub-channel thermal hydraulics code and CFD codes. These earlier developed code systems allow modeling of the thermal hydraulics phenomena occurring during reactor transients and accidents in greater detail. Still these code systems lack a sufficiently sophisticated fuel behavior model, which is able i.e. to take into account the fission gas behavior during normal operation, off-normal conditions and transients. To our knowledge a two-way coupling to a fuel performance code hasn’t so far been reported in the open literature for calculating a full core with detailed and well validated fuel behavior models.
A new two-way coupling approach between DYN3D and the fuel performance code TRANSURANUS is presented. In the coupling, DYN3D provides the time-dependent rod power and thermal hydraulics conditions to TRANSURANUS, which in turn transfers parameters like fuel temperature and cladding temperature back to DYN3D. The main part of the development is a general TRANSURANUS coupling interface that is applicable for linking of any other reactor dynamics codes, thermal hydraulics system codes and sub-channel codes to TRANSURANUS. Beside its generality, other features of this interface are the application at either fuel assembly or fuel rod level, one-way or two-way coupling, automatic switching from steady to transient conditions in TRANSURANUS (including update of the material properties etc.), writing of all TRANSURANUS output files and the possibility of manual pre- and post-calculations with TRANSURANUS in standalone mode. The TRANSURANUS code can be used in combination with this coupling interface in various scenarios: different fuel compositions in the reactor types BWR, PWR, VVER, HWR and FBR, considering time scales from milliseconds (i.e. RIA) over seconds/ minutes (i.e. LOCA) to years (i.e. normal operation) and thence different reactor states.
Results of DYN3D-TRANSURANUS are shown for a control rod ejection transient in a German PWR. In particular, it appears that for all burn-up levels the two-way coupling approach systematically calculates higher maximum values for the node fuel enthalpy (max. difference of 46 J/g) and node centerline fuel temperature (max. difference of 181 K), compared to DYN3D standalone in best estimate calculations. These differences can be completely explained by the more detailed TRANSURANUS modeling of fuel thermal conductivity, radial power density profile and heat transfer in the gap. As known from fuel performance codes, the modeling of the heat transfer in the gap is sensitive and causes also larger differences in case of low burn-up.
The numerical convergence for DYN3D-TRANSURANUS is quick and stable. The coupled code system can improve the assessment of safety criteria, at a reasonable computational cost with a CPU time of less than seven hours without parallelization.
HFE Safety Evaluation in Angra-1 NPP for the Preparation and Inclusion of a Chapter 18 in the Plant Final Safety Analysis Report
Authors: Alonso Pedro Trueba , Valdivia Juan Carlos , Illobre Luís Fernández , Hulsmans Mark 
Published: November 2014

Angra-1 Nuclear Power Station (Westinghouse PWR-600 MW, 2 loops) started commercial operation in 1985, being property of Eletronuclear, subsidiary of Eletrobras in Brazil. Angra-1 has been preparing the necessary measures to renew the operating license and to apply for a lifetime extension up to 60 years.
Among the many activities to perform, there are some related to fulfilling the requirements of the Brazilian regulator, the CNEN. These include requirements related to Human Factors Engineering (HFE) that included the preparation of a Chapter 18 of HFE, to become part of the plant’s Final Safety Analysis Report (FSAR).
In the framework of the Instrument for Nuclear Safety Cooperation (INSC), created and funded by the European Union (EU) to enhance nuclear safety world-wide, cooperation activities between the EU and the Government of Brazil were set up in 2009. One of the INSC projects funded was to support the Brazilian nuclear operator of Angra-1 in the field of HFE. In 2010, the implementation of the project was awarded to a consortium lead by Tecnatom for performing a HFE Safety Evaluation to the plant and to provide support for preparing this Chapter 18.
For this Project a specific methodology was developed for the execution of the Safety Evaluation. The methodology has been developed for evaluating — from the HFE viewpoint — a plant in operation, from the beginning of commercial operation until nowadays, including the design modifications performed to date. The obtained results have been used for developing the aforementioned Chapter 18.
The main results of the Project Execution have been:
1. The developed methodology has made it possible to perform a comprehensive HFE evaluation of Angra-1, including the analysis of Post-TMI requirements, the design included in the current FSAR, the existing Angra-1 procedures and the verification of the current Main Control Room.
2. Technical support has been provided to Angra-1 for the preparation of Chapter 18 of the FSAR, following the structure of NUREG-0711, and using the results of the HFE Safety Evaluation.
3. An Action Plan has been developed for identifying and addressing in the future all those deficiencies found during the HFE Safety Evaluation, as well as those activities that are the consequence of the new FSAR Chapter 18.