bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complete basis set extrapolations of dispersion, exchange, and coupled‐clusters contributions to the interaction energy: a helium dimer study
Authors: Jeziorska Małgorzata , Cencek Wojciech , Patkowski Konrad , Jeziorski Bogumił , Szalewicz Krzysztof 
Published: May 2008

AbstractEffectiveness of various extrapolation schemes in predicting complete basis set (CBS) values of interaction energies has been investigated for the helium dimer as a function of interatomic separation R. The investigations were performed separately for the leading dispersion and exchange contributions to the interaction energy and for the interaction energy computed using the coupled cluster method with single and double excitations (CCSD). For all these contributions, practically exact reference values were obtained from Gaussian‐type geminal calculations. Sequences of orbital basis sets augmented with diffuse and bond functions or augmented with two sets of diffuse functions have been employed, with the cardinal numbers up to X = 7. The functional form EX = ECBS + A(X − k)−α was applied for the extrapolations, where EX is the contribution to the interaction energy computed with a basis set of cardinal number X. The main conclusion of this work is that CBS extrapolations of an appropriate functional form generally improve the accuracy of the interaction energies at a very small additional computational cost (of the order of 10%) and should be recommended in calculations of interatomic and intermolecular potentials. The effectiveness of the extrapolations significantly depends, however, on the interatomic separation R and on the composition of the basis set. Basis sets with midbond functions, well known to provide at a given size much more accurate nonextrapolated results than bases lacking such functions, have been found to perform best also in extrapolations. The X−1 extrapolations of dispersion energies computed with midbond function turned out to be very efficient (except at large R), reducing the errors by an order of magnitude for small X and a factor of two for large X (where the errors of nonextrapolated results are already very small). If midbond functions are not used, the X−3 formula is most appropriate for the dispersion energies. For the exchange component of the interaction energy, the best results are obtained—in both types of basis sets—with the X−4 extrapolation, which leads (in both cases) to almost an order of magnitude reduction of the error. The X−3 and (X − 1)−3 extrapolations work also well, but give smaller improvements. The correlation component of the CCSD interaction energy extrapolates best with α between 2 and 3 for bases with midbond functions and between 3 and 4 for bases without such functions. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Ultra‐high accuracy calculations for hydrogen molecule and helium dimer
Authors: Cencek Wojciech , Szalewicz Krzysztof 
Published: May 2008

AbstractLarge basis sets of explicitly correlated Gaussian (ECG) functions with carefully optimized nonlinear parameters have been used to calculate the binding energies of H2 and He2 at their equilibrium internuclear distances R. In the case of the helium dimer, the wave function includes a product of two helium atom functions, which accounts for the main part of the total energy. At R = 1.4 bohr, a strict upper bound to the H2 total energy in the Born‐Oppenheimer approximation is equal to −1.174 475 714 220 363 hartree and the complete basis set (CBS) limit is estimated as −1.174 475 714 220 44(6) hartree. At R = 1.4011 bohr, the corresponding values are −1.174 475 931 400 135 and −1.174 475 931 400 21(6). A strict upper bound to the interaction energy of He2 at R = 5.6 bohr is −11.00035 K and the CBS limit is −11.0006(2) K. The results for both systems are significantly more accurate than any results reported in literature. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Addition of spawning gravel—a means to restore spawning habitat of atlantic salmon (Salmo salar L.), and Anadromous and resident brown trout (Salmo trutta L.) in regulated rivers
Authors: Barlaup Bjørn T. , Gabrielsen Sven Erik , Skoglund Helge , Wiers Tore 
Published: May 2008

AbstractIn regulated rivers, canalization and reduced water discharge may lead to loss or impairment of salmonid spawning areas, and thereby negative effects on stock recruitment. We discuss the possibility of mitigating such effects through establishing new spawning areas by addition of gravel. We monitored the occurrence of nests in seven gravel deposition sites in five different Norwegian rivers. The total area covered by each of the depositions spanned from 25 m2 to 300 m2. The areas were examined for nests during a 2–5 year period following the addition of gravel, that is, a total of 27 spawning periods. The fish were found to spawn at all localities and years with the exception of two occasions when gravel was lost during floods. Spawning success measured as egg survival was generally high (>80%). These results show that the additions met the criteria for successful spawning. Nests of Atlantic salmon were found to be aggregated in the area with the highest water current. However, successful nests were also found in areas with added gravel where the water current was much reduced. This unusual selection of spawning site most likely reflects the lack of other, more favourable spawning areas. The results therefore suggest that gravel additions can be successful even if the only available areas are suboptimal with respect to water flow and water depth. Three of the seven localities were unsuitable as the gravel was partly or totally displaced downstream during floods. At two of these localities, nests were probably lost because the floods occurred after the spawning season. This shows that large floods can be a major drawback. Monitoring of the spawning success and displacement of gravel is therefore essential to evaluate the method. Subsequently, stable areas, favoured by the spawners, can be expanded by supplementary addition of gravel. In sum, the results show that the careful addition of gravel areas can be used to provide suitable spawning locations for salmonids in regulated rivers. Copyright © 2008 John Wiley & Sons, Ltd.
Long‐term brown trout populations responses to flow manipulation
Authors: Sabaton Catherine , Souchon Yves , Capra Herve , Gouraud Veronique , Lascaux Jean‐Marc , Tissot Laurence 
Published: May 2008

AbstractDespite the many habitat simulations that have been undertaken around the world, not enough biological monitoring has been performed following flow manipulations. It is difficult, however, to refine flow management decisions without a better understanding of the links between amounts, durations and seasonality of flow deliveries and population dynamics.Trout populations were monitored before and after flow alterations in five trout streams, involving 17 study sites over a 4‐ to 12‐year period, depending on the sites.A comparison of the trout populations observed to theoretical habitat/population models pointed up several helpful lessons. Various factors slow increases in population size, including the availability and quality of spawning grounds, the general connectivity of the bypass section (BPS) and severe spate events. In addition to these site‐dependent factors, hydrological dynamics may explain why it is so difficult to clearly identify relationships between habitat availability and real fish stocks. Moreover, opportunities to observe population changes are improved when the pre‐enhancement instream flow value is very low, and when there is a considerable difference between pre‐ and post‐enhancement values. A population dynamics model that incorporates different habitat limitations and demographic background can be a very precious tool to improve understanding of the different situations and to build scenarios of population recovery. Copyright © 2008 John Wiley & Sons, Ltd.
Changes in riparian habitats along five major tributaries of the saint Lawrence river, QuÉbec, Canada: 1964–1997
Authors: Charron Isabelle , Lalonde Olivier , Roy André G. , Boyer Claudine , Turgeon Samuel 
Published: May 2008

AbstractThis paper investigates spatiotemporal changes over a 30‐year period within the riparian landscapes of five major tributaries of the Saint Lawrence River (Québec, Canada). Aerial photographs from 1964(1967) for the Saint Maurice, Saint François, Richelieu, Batiscan and Yamachiche Rivers were compared with 1997 photographs to quantify changes in vegetation and land use. The riparian zones were divided into five cover types to create landscape cover maps: herbaceous vegetation, woody vegetation, agriculture, urban and water. The maps were converted into a geographic information system to quantify landscape changes, which were attributed to either natural processes, such as sediment deposition and bank erosion, or anthropogenic influences, such as human settlement. The results show that both natural and anthropogenic changes were limited over the 30‐year study period and that natural processes dominated over human‐caused impacts. Overall, riparian vegetation patches became more fragmented and isolated with time due to the disturbances. However, important differences were observed between and within rivers. Fluvial processes resulted in riparian vegetation losses on three rivers (Richelieu, Saint François and Batiscan) and gains on the other two rivers (Yamachiche and Saint Maurice) while anthropogenic influences resulted in vegetation gains on four rivers, except the Richelieu where gains and losses were equivalent. Thus, while riparian landscapes are sensitive to both fluvial and anthropogenic processes, there is great variability in sensitivity among the tributaries. By providing a better understanding of past changes, studies such as this can help make better predictions of future changes that are expected to occur with climate change. Copyright © 2008 John Wiley & Sons, Ltd.
An environmental scanning electron microscopy study of aqueous gibbsite suspensions
Authors: Houghton H.A. , Donald A.M. 
Published: May 2008

AbstractSynthetic gibbsite has been used as a model system for study in the environmental scanning electron microscopy (ESEM), to probe its utility as a tool to study clay dispersions under different conditions of aggregation. We have been able to show that we can study the nature of the platelet interactions as the pH is altered, by imaging the dispersions after water evaporation from the surface to permit the surface of the platelets to be clearly seen. It has been possible to show that at alkaline pH there are very few face–edge contacts between the platelets, consistent with what is known about the charges at high pH on the faces and edges of the gibbsite. In contrast, at lower pHs, when faces and edges have opposite sign charges, there are significantly more platelets touching with edge and faces in contact. Finally, when the salt lithium chloride is added to a dispersion at approximately neutral pH, the plates appear to stack suggesting face–face interactions in the dispersion. Thus, ESEM has been able to demonstrate the variability of packing in gibbsite dispersions and to correlate the structures observed with the known charge distribution on the gibbsite platelets. SCANNING 30: 223–227, 2008. © 2008 Wiley Periodicals, Inc.
Making sense of argumentation and explanation
Authors: Berland Leema Kuhn , Reiser Brian J. 
Published: May 2008

AbstractConstructing scientific explanations and participating in argumentative discourse are seen as essential practices of scientific inquiry (e.g., R. Driver, P. Newton, & J. Osborne, 2000). In this paper, we identify three goals of engaging in these related scientific practices: (1) sensemaking, (2) articulating, and (3) persuading. We propose using these goals to understand student engagement with these practices, and to design instructional interventions to support students. Thus, we use this framework as a lens to investigate the question: What successes and challenges do students face as they engage in the scientific practices of explanation and argumentation? We study this in the context of a curriculum that provides students and teachers with an instructional framework for constructing and defending scientific explanations. Through this analysis, we find that students consistently use evidence to make sense of phenomenon and articulate those understandings but they do not consistently attend to the third goal of persuading others of their understandings. Examining the third goal more closely reveals that persuading others of an understanding requires social interactions that are often inhibited by traditional classroom interactions. Thus, we conclude by proposing design strategies for addressing the social challenges inherent in the related scientific practices of explanation and argumentation. © 2008 Wiley Periodicals, Inc. Sci Ed 93:26–55, 2009
Surface characteristics of AZ91D alloy anodized with various conditions
Authors: Park Il Song , Jang Yong Seok , Kim Yu Kyoung , Lee Min Ho , Yoon Jeong Mo , Bae Tae Sung 
Published: May 2008

AbstractAnodic oxidation of an AZ91D magnesium alloy was carried out in an attempt to increase the corrosion resistance. The alloy was placed in an electrolyte containing 0.1 M sodium silicate (Na2SiO3), 2.0 M sodium hydroxide (NaOH) and 0.1 M sodium phosphate (Na3PO4), and treated with a current density of 100–400 mA/cm2 for 1 to 4 min. After the anodic oxidation treatment, the surface characteristics were analyzed by SEM, X‐ray diffraction (XRD) and a surface roughness tester. The corrosion resistance was determined by measuring the corrosion potential and corrosion current density using potentiodynamic polarization in a 3.5 wt% NaCl electrolyte solution. Although the anodic oxidation treatment with the base electrolyte resulted in an arrival voltage ranging from 60 to 70 V, the addition of silicate tended to reduce this arrival voltage by approximately 10–20 V and decrease the critical voltage required for the formation of a porous oxide film. The pore size and film thickness increased with increasing applied current and treatment time. The addition of silicate to the electrolyte resulted in films with a homogeneous pore size and a film thickness increasing with the increasing applied current and treatment time. XRD showed the formation of a new MgO and Mg2SiO4 phase. The formation of Mg2SiO4 was attributed to the presence of SiO44− in the film. After the addition of silicate, the corrosion potential increased and corrosion current decreased, resulting in improved corrosion resistance. Copyright © 2008 John Wiley & Sons, Ltd.
Microscopic computed tomography imaging of the cerebral circulation in mice: Feasibility and pitfalls
Authors: Abruzzo T. , Tumialan L. , Chaalala C. , Kim S. , Guldberg R.E. , Lin A. , Leach J. , Khoury J.C. , Morgan A.E. , Cawley C.M. 
Published: May 2008

AbstractThis study evaluates the utility and practical limitations of microcomputerized X‐ray tomography (CT) as a research tool for examination of the cerebral circulation in mice. Six micro CT angiograms of the circle of Willis (COW) from six mice were obtained by scanning whole head and brain specimen perfused with a radio‐opaque silicone contrast agent. Two‐dimensional volume rendered images were postprocessed from three‐dimensional image datasets using a partially automated high‐throughput model that generated 10 surface projections for each specimen. The image processing model employed a straightforward global thresholding and computerized component labeling software algorithm. Postprocessed images were analyzed and results correlated with microdissection. Micro CT demonstration of COW vessels and their branch anatomy was assessed. 71% of COW vessels were completely demonstrated, 26% were partially demonstrated, and 3% were not demonstrated. All cases of nondemonstration and most cases of partial demonstration resulted from scan coverage or postprocessing clip error. Thresholding effect caused pseudostenosis of 8% of COW vessels and accounted for a minority of partial demonstration cases. No imaging artifacts were caused by contrast extravasation or ineffective contrast perfusion. Volume averaging caused minor angioarchitectural distortion of 58% of COW vessels. Ninety‐five percent of COW ≥50 μm and 52% of COW vessels <50 μm were correctly identified by micro CT. Micro CT of the murine COW using a high‐throughput image processing model is feasible. Angioarchitectural distortion due to volume averaging and thresholding effect can occur and pathological findings should be confirmed. Synapse 62:557–565, 2008. © 2008 Wiley‐Liss, Inc.
Genetic and pharmacological manipulations of the CB1 receptor alter ethanol preference and dependence in ethanol preferring and nonpreferring mice
Authors: Vinod K. Yaragudri , Yalamanchili Ratnakumar , Thanos Panayotis K. , Vadasz Csaba , Cooper Thomas B. , Volkow Nora D. , Hungund Basalingappa L. 
Published: May 2008

AbstractRecent studies have indicated a role for the endocannabinoid system in ethanol‐related behaviors. This study examined the effect of pharmacological activation, blockade, and genetic deletion of the CB1 receptors on ethanol‐drinking behavior in ethanol preferring C57BL/6J (B6) and ethanol nonpreferring DBA/2J (D2) mice. The deletion of CB1 receptor significantly reduced the ethanol preference. Although the stimulation of the CB1 receptor by CP‐55,940 markedly increased the ethanol preference, this effect was found to be greater in B6 than in D2 mice. The antagonism of CB1 receptor function by SR141716A led to a significant reduction in voluntary ethanol preference in B6 than D2 mice. A significant lower hypothermic and greater sedative response to acute ethanol administration was observed in both the strains of CB1 −/− mice than wild‐type mice. Interestingly, genetic deletion and pharmacological blockade of the CB1 receptor produced a marked reduction in severity of handling‐induced convulsion in both the strains. The radioligand binding studies revealed significantly higher levels of CB1 receptor‐stimulated G‐protein activation in the striatum of B6 compared to D2 mice. Innate differences in the CB1 receptor function might be one of the contributing factors for higher ethanol drinking behavior. The antagonists of the CB1 receptor may have therapeutic potential in the treatment of ethanol dependence. Synapse 62:574–581, 2008. Published 2008 Wiley‐Liss, Inc.
Application of systems engineering and information models to optimize operation of gas export systems
Authors: Stærkebye Nørstebø Vibeke 
Published: May 2008

AbstractThis paper presents the use of systems engineering in analysis and optimization of gas export system operation. The Norwegian dry gas export system is selected as the subject for the analysis. The gas export system at the Norwegian Continental Shelf is the largest offshore gas transport network in the world, and it consists of many components, such as pipelines, platforms, processing and exit terminals, and many routing possibilities. There are two important factors that a gas export system shall satisfy. First, the system shall secure that the customers receive the gas that they have ordered. Second, the system shall do this in as energy efficient way as possible, i.e., minimize operating costs and environmental emissions. For the operator of gas export systems it is of vital importance that equipments and pipelines in the system are optimally integrated. This will secure flexibility, capability, availability and energy efficiency of the system, and enhance understanding between different system operators. Operational experience shows that there is a substantial need to analyze the integration between the system components and the effects on optimum operation, energy consumption and environmental emissions. The objective of this work is to demonstrate how systems engineering and information models have been applied as tools for analyzing the integration in and overcoming the complexity of gas export systems and system operation, and further for developing models that optimize the energy efficiency of system operation. © 2008 Wiley Periodicals, Inc. Syst Eng
Mouse toxicity of Anabaena flos‐aquae from Lake Dianchi, China
Authors: Pan Xiaojie , Chang Fengyi , Liu Yongding , Li Dunhai , Xu Aihua , Shen Yinwu , Huang Zebo 
Published: May 2008

AbstractSome species of the genera Anabaena can produce various kinds of cyanotoxins, which may pose risks to environment and human health. Anabaena has frequently been observed in eutrophic freshwater of China in recent years, but its toxicity has been reported only in a few studies. In the present study, the toxicity of an Anabaena flos‐aquae strain isolated from Lake Dianchi was investigated. Acute toxicity testing was performed by mouse bioassay using crude extracts from the lyophilized cultures. The mice exposed to crude extracts showed visible symptoms of toxicity and died within 10–24 h of the injection. Serum biochemical parameters were evaluated by the use of commercial diagnostic kits. Significant alterations were found in the serum biochemical parameters: alkaline phosphatase (AKP), γ‐glutamyl transpeptidase (γ‐GT), aspartate amino transferase (AST), alanine amino transferase (ALT), AST/ALT ratio, total protein content, albumin content, albumin/globulin (A/G) ratio, blood urea nitrogen (BUN), serum creatinine (Ssr), and total antioxidative capacity (T‐AOC). Histopathological observations were carried out with hematoxylin and eosin (HE) stain under light microscope. Severe lesions were seen in the livers, kidneys, and lungs of the mice injected with crude extracts. The alterations of biochemical parameters were in a dose‐dependent manner, and the severities of histological lesions were in the same manner. Based on biochemical and histological studies, this research firstly shows the presence of toxin‐producing Anabaena species in Lake Dianchi and the toxic effects of its crude extracts on mammals. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.