bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experience and Problem Representation in Statistics
Authors: Rabinowitz Mitchell , Hogan Tracy M. 
Published: May 2010

Abstract
This research investigated experience level differences in problem representation in statistics. A triad judgment task was designed so that source problems shared either surface similarity (story narrative) or structural (inferential level) features (t test, correlation, or chi-square) with the target problem. Graduate students with varying levels of experience in statistics were asked to choose which source problem "goes best" with the target problem for each triad. Given a choice between a problem that shares surface-level characteristics and one that shares inferential-level characteristics, students who had taken 0 to 4 courses in statistics tended to represent problems on the basis of surface-level features. Students who had more than 4 courses did not consistently make choices on the basis of surface-level features, nor did they consistently rely on structural features. However, all students with statistics course backgrounds noticed structural features when competition between different types of features was eliminated. The role of surface and structural features in determining problem representations is discussed.
The Early Bird Does Not Get the Worm: Time-of-Day Effects on College Students’ Basic Cognitive Processing
Authors: Allen Philip A. , Grabbe Jeremy , McCarthy Ann , Bush Aryn Harrison , Wallace Benjamin 
Published: May 2010

Abstract
We conducted a neuropsychological and cognitive assessment study to determine whether time of day affects cognitive performance. We measured executive control (fluency), processing speed, semantic memory, and episodic memory performance. We followed 56 students across 3 different times of day, testing performance on vocabulary, fluency, processing speed, and episodic memory. Results showed an advantage for fluency and digit symbol task performance in the afternoon and evening testing times relative to morning testing (regardless of testing order), but that time of day did not affect semantic or episodic memory performance. These results suggest that optimal executive functioning and processing speed may occur for typical college students in the afternoon and evening regardless of time-of-day preference.
Methodological Issues in the Provenance Investigation of Early Formative Mesoamerican Ceramics
Authors: Neff Hector , Blomster Jeffrey , Glascock Michael D. , Bishop Ronald L. , Blackman M. James , Coe Michael D. , Cowgill George L. , Diehl Richard A. , Houston Stephen , Joyce Arthur A. , Lipo Carl P. , Stark Barbara L. , Winter Marcus 
Published: May 2010

AbstractA recent study of Early Formative Mesoamerican pottery by instrumental neutron activation analysis (INAA) yielded surprising results that prompted two critiques in the Proceedings of the National Academy of Sciences. The INAA study indicated that the Olmec center of San Lorenzo was a major exporter of carved-incised and white pottery and that little if any pottery made elsewhere was consumed at San Lorenzo. The critiques purport to "overturn" the INAA study and demonstrate a more balanced exchange of pottery among Early Formative centers. However, the critiques rely on a series of mistaken claims and misunderstandings that are addressed here. New petrographic data on a small sample of Early Formative pottery (Stoltman et al. 2005) are potentially useful, but they do not overturn INAA of nearly 1000 pottery samples and hundreds of raw material samples.
Architecture, Caching, and Foreign Contacts at Chac (II), Yucatan, Mexico
Authors: Smyth Michael P. 
Published: May 2010

AbstractThe Puuc region of northern Yucatan was one of the most important areas of Maya civilization during the Terminal Classic florescent period. Despite its importance to Maya prehistory, there is little understanding of the times prior to the great cultural florescence. Eight seasons of research at Chac II provide new information regarding an important Maya center between the Classic and Terminal Classic periods (A.D. 300–800), including the changing nature of influence and contacts with foreign groups reaching central Mexico. The great antiquity of Chac, the presence of numerous substructures, and the variety of architectural styles in the Great Pyramid Plaza suggest that the site was an originator of the Early Puuc architectural style. It is argued that the major ritual offering below the central monument at the Gran Plaza re-creates the “turquoise” hearth reenacting the birth of the Fifth Sun at Teotihuacan. These new data are transforming understanding of the Puuc Maya and their relations with greater Mesoamerica.
Early Maya Adaptive Patterns: Mid-Late Holocene Paleoenvironmental Evidence from Pacific Guatemala
Authors: Neff Hector , Pearsall Deborah M. , Jones John G. , Arroyo Bárbara , Collins Shawn K. , Freidel Dorothy E. 
Published: May 2010

AbstractWe summarize what is known about Archaic period occupation of southeastern Mesoamerica and Central America as background for presenting new paleoenvironmental evidence of pre-Early Formative human impacts on the landscape of Pacific coastal Guatemala. Our evidence comes from sediment cores in three locations, all of which are in the mangrove-estuary zone of the lower coast. Pollen and phytoliths from the cores document increased burning, decreased forest cover, the appearance of domesticates, and increased disturbance indicators at various times during the Archaic period, the earliest being around 3500 cal B.C. The available evidence demonstrates that shifting horticulture was an early and widespread adaptation to the southeastern Mesoamerican deciduous tropical forest and constituted the base from which later adaptations, including that of early Maya farmers, differentiated. Early Formative adaptive innovations may have been favored by shifts in return rates from various estuarine and terrestrial resources during a dry and variable interval 2000 and 1500 cal B.C.
El Templete Tulán de la Puna de Atacama: Emergencia de Complejidad Ritual Durante el Formativo Temprano (Norte de Chile)
Authors: Núñez Lautaro , Cartajena Isabel , Carrasco Carlos , Souza Patricio de 
Published: May 2010

ResumenExcavaciones en las tierras altas del occidente de la Puna de Atacama han identificado una estructura templaria datada entre los 2630 ± 60 a 2490 ± 80 a.P. (no calibradas) en el centro de un montículo ocupacional estratificado, inserta en un asentamiento aldeano pastoralista. La arquitectura monumental registrada en el sitio Tulán-54, perteneciente a la fase Tilocalar (3030 ± 70 a 2380 ± 70 a.P.) es contemporánea con el período Formativo Temprano del altiplano central y meridional. Sin embargo, de acuerdo a su patrón arquitectónico e indicadores culturales no presenta analogía con el área centro sur andina. Un análisis cronoestratigráfico, contextual y tecnológico, permitió establecer una secuencia Arcaico-Formativa, incluyendo una fase transicional entre ambos períodos y caracterizar a la vez el desarrollo ocupacional del montículo. Estas evidencias permiten proponer que el proceso circumpuneño de emergencia de complejidad sociocultural tendría un carácter autónomo e independiente de las relaciones pan-andinas en términos de núcleo-periferia.
Montículos de la Cuenca de la Laguna Merín: Tiempo, Espacio y Sociedad
Authors: Boksar Roberto Bracco 
Published: May 2010

ResumenLa cuenca de la Laguna Merín fue habitada, durante cinco milenios, por pueblos constructores de montículos, responsables de la modificación antrópica más notable que experimentaron las llanuras de las latitudes medias sudamericanas. La composición, tamaño, densidad y distribución de los sitios hizo que las investigaciones se centraran en los procesos de "complejización". Similitudes con otros contextos motivaron la adopción de modelos explicativos generados para otras realidades culturales, causando la pérdida de visión de lo propio del registro regional. A través de la dimensión espacial y temporal se aborda el fenómeno cultural, discutiendo las interpretaciones funcionalistas. Más de 80 dataciones 14C sustentan que estas construcciones se elevaron en forma paulatina y continua. La distribución muestra que los sitios se concentran en los lugares de mayor productividad. Los ciclos de crecimiento de los montículos de India Muerta - Paso Barrancas evidencian vínculos con la historia ambiental. Por otra parte dentro de los conjuntos de montículos se advierten arreglos y distancias que se repiten entre sitios. Al interpretar el crecimiento de cada cerrito como asociado a un actor social, observamos como distancias y arreglos espaciales pasan a tener significado social; comportándose el registro, en desarrollo temporal, como un sistema de reproducción social.
Language, History and Prehistory: Mississippian Lexico-Reconstruction
Authors: Mochon Marion Johnson 
Published: May 2010

AbstractLexico-reconstruction techniques are used to examine the possible affinities between speakers of the Muskogean and Siouan families and the bearers of Mississippian culture. Lexical data are presented in terms of a typology of social systems which is descriptive of the range of socio-cultural complexity which characterizes Mississippian communities and societies. These social systems are defined as: descent-ranked societies, genealogy-ranked societies, and stratified societies. Non-material aspects of Mississippian culture are also examined. These suggest a concern with calendrics and the presence of mathematical decimal systems.
Archaic Funerary Pattern or Postdepositional Alteration? The Patapatane Burial in the Highlands of South Central Andes
Authors: Santoro Calogero M. , Standen Vivien G. , Arriaza Bernardo T. , Dillehay Tom D. 
Published: May 2010

AbstractThe burial found at Patapatane Cave in the highlands of Arica, northern Chile, yielded an incomplete skeleton of a 20-to-23-year-old female, dating to the end of the Middle Archaic period at 5910 ± 90 B.P. The site is located in a semiarid environment on the eastern side of Sierra de Huaylillas at 3800 m. in the hinterland of Arica, northern Chile. We argue that the missing bones, position of the cranium, and breakage of some elements resulted from both postdepositional human intervention and taphonomic processes. The body was laid to rest in a supine position and after it became skeletonized hunters revisited the inhumation and removed some bone elements. However, the other bones present in situ were not displaced and remained in proper anatomical position, with the exception of the cranium, which was placed vertically on top of the cervical vertebrae. The observed breakage of vertebrae, long bones, and skull seems to have been the result of taphonomic, nonanthropogenic, postburial actions. In reporting on the Patapatane burial, Archaic period funerary patterns from western South America are reviewed to support the notion that early hunters and gatherers systematically manipulated their dead through perimortem and postmortem alterations. These included several processes: (1) processes of body reduction and transformation by removal of body sections or removal of bone elements, cremation, and human remains discarded in domestic middens; and (2) processes of artificial preservation of the dead that included roasting, salting, and artificial mummification. In addition, we recognize the simultaneous existence of intact primary burial and that other skeletons were possibly altered accidentally by postdepositional natural or cultural agents.
Interregional Relationships in Mesoamerica: Interpreting Maya Ceramics at Teotihuacan
Authors: Clayton Sarah C. 
Published: May 2010

AbstractInteraction between distant, culturally distinct, complex societies can significantly impact the sociopolitical development of the societies involved. In Classic period Mesoamerica, the urban center of Teotihuacan was a dominant force in the Valley of Mexico, and there is compelling evidence that its influence extended well beyond this region. The role of Teotihuacan in the political development of Maya cities has been debated for decades, though interaction may have also included exchange and the presence of Maya individuals at Teotihuacan. In this study I investigate interaction between Teotihuacan and several Maya polities through typological, spatial, and compositional analyses of Maya ceramics found at Teotihuacan. Data from instrumental neutron activation analysis are used to identify probable subregions from which Maya ceramics were imported to Teotihuacan. Results indicate that diverse Maya polities interacted with Teotihuacan over the course of five centuries, and that relationships involving polities in the central Petén region were particularly long-lived. This research has important implications for understanding the sociopolitical histories of Mesoamerican complex societies specifically, and interaction among complex societies in general.
Using Refuse Disposal Patterns to Infer Olmec Site Structure in the San Lorenzo Region, Veracruz, Mexico
Authors: Wendt Carl J. 
Published: May 2010

AbstractIn this paper, I use data gathered from recent excavations conducted in the San Lorenzo region to explore the nature of Olmec site structure. Most studies dealing with this topic have focused on ceremonial precincts at large regional centers. Recent archaeological investigations conducted at the low lying Early Formative period (1500–900 B.C., radiocarbon years) site of El Remolino provide a unique opportunity to study how the Olmec organized domestic space outside primary centers. Although no easily identifiable structural remains were found at El Remolino, refuse disposal patterns are used to infer architectural arrangement and also provide clues on site layout. In order to investigate variations in household spatial structure in the San Lorenzo region, the Remolino data are compared with results from household archaeological studies conducted in an elite precinct (the Group D area) at the regional center of San Lorenzo. Findings indicate that household spatial layout at El Remolino ascribed to a residentially dispersed house-lot type of spatial patterning, whereas spatial structure in the Group D area of San Lorenzo adheres closer to the more nucleated house compound type of spatial patterning.
Fabrication of Density Gradients of Biodegradable Polymer Microparticles and Their Use in Guiding Neurite Outgrowth
Authors: Li Xiaoran , MacEwan Matthew R. , Xie Jingwei , Siewe Daku , Yuan Xiaoyan , Xia Younan 
Published: May 2010

AbstractA new method for generating both continuous and discrete density gradients in microparticles of biodegradable polymers via an electrospray technique is reported. The gradients are generated by spatially varying the deposition time of electrosprayed microparticles. The substrate coated with a density gradient of microparticles has varying surface roughness, offering a unique system for studying the effect of physical cues on neurite outgrowth from dorsal root ganglia. An optimal surface roughness for promoting neuron adhesion and neurite extension in vitro is obtained. Furthermore, this capability of approach is extended to generate a gradient of fluorescein isothiocyanate labeled bovine serum albumin by encapsulating it in the polymer microparticles in situ during electrospray. Taken together, this new class of substrates with gradients of microparticle density can potentially be used in various biomedical applications such as neural tissue engineering.
Applying soft computing methods to fluorescence modeling of the polydimethylsiloxane/silica composites containing lanthanum
Authors: Curteanu Silvia , Nistor Alexandra , Curteanu Neculai , Airinei Anton , Cazacu Maria 
Published: May 2010

AbstractLanthanum, as a fluorescent element, was encapsulated in complexing silica xerogel by using a one‐pot procedure: silica formation from tetraethyl‐orthosilicate and 3‐aminopropyltriethoxysilane, its chemical modification by reacting with 2,4‐dihydroxybenzaldehyde, and lanthanum complexation through the formed hydroxy‐azomethine groups occurred in the same reaction system. A polydimethylsiloxane‐α,ω‐diol with average number molecular weight of 20,000 was added in the sol–gel system to facilitate obtaining the flexible, free‐standing films. Using different molar ratios among the reactants, a series of experiments was performed and the fluorescence of the resulted compounds was evaluated, since the photophysical properties of the prepared compounds strongly depend on the composition. The acquired data have been used for fluorescence modeling based on soft computing instruments. Neural network models, individually or aggregated in stacks, were developed to estimate the fluorescence intensity depending on the reaction mixture composition: tetraethyl‐orthosilicate, 3‐aminopropyltriethoxysilane, 2,4‐dihydroxybenzaldehyde, lanthanum acetate, and polydimethylsiloxane‐α,ω‐diol amounts. A procedure based on genetic algorithms was used to design simple neural networks. Two main goals are pointed out in this article: developing a general methodology for modeling the complex processes with simple or stacked neural networks, and demonstrating the improvement of the modeling performance by combining different neural networks. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Evaluation of properties of unsaturated polyester/acetylated hydroxypropyl guar gum composites
Authors: Shenoy M. A. , D'Melo D. J. 
Published: May 2010

AbstractGuar gum is a naturally occurring galactomannan, which is extremely hydrophilic in nature. Hydroxypropyl guar gum (HPG) was subjected to acetylation using acetic anhydride and pyridine. The effect of the reduction in the hydrophilic nature of the polymer on its filler properties was studied by using the derivatized guar gum as filler in an unsaturated polyester composite. The effect of degree of substitution and the concentration of filler on the rheological, chemical, and mechanical properties of the composites were studied. Results indicated that an increase in the acetate content in the HPG resulted in an increased polymer–filler interaction. However, the composites resulting from these derivatized HPGs showed reduced mechanical properties. This decrease in the mechanical properties were attributed to the decrease in the hydrogen bonding in the filler particles, thus reducing the cohesiveness and strength of the filler particles themselves. Thus, polysaccharides can be used as fillers but chemically modifying them results in a change in the basic nature of the filler itself and is not just restricted to surface modification as is the case of inorganic fillers and fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Investigation of the phase morphology of dynamically vulcanized PVC/NBR blends using atomic force microscopy
Authors: Gheno S. M. , Passador F. R. , Pessan L. A. 
Published: May 2010

AbstractDynamic vulcanization is a mixing process employed in the melt state of elastomers with thermoplastics. This process may result in the formation of thermoplastic vulcanized (TPV) materials with improved properties such as mechanical strength, Young's modulus, hardness, and abrasion fatigue. In this study, a vulcanized thermoplastic was obtained by the dynamic vulcanization of poly(vinyl chloride)/acrylonitrile butadiene rubber (PVC/NBR) blends using a curative system based on sulfur (S)/tetramethylthiuram disulfide (TMTD) and mercaptobenzothiazyl disulfide (MBTS). The formation of crosslinks was characterized by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The mechanical properties were analyzed by tensile tests and the phase morphology was investigated using atomic force microscopy (AFM) operating in the tapping mode‐AFM. The phase images of the dynamically vulcanized blends showed an elongated morphology, which can be associated to the formation of crosslinks that give the material its excellent mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Comparative investigation on crystallization conditions dependence of polymorphs composition for β‐nucleated propylene/ethylene copolymer and propylene homopolymer
Authors: Xiao Wenchang , Feng Jiachun 
Published: May 2010

AbstractThe crystallization conditions dependence of polymorphs composition in β nucleated propylene/ethylene copolymers (PPR) and propylene homopolymers (PPH) were comparatively investigated via wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) measurements. It is interesting to note that the amount of β form as a function of crystallization conditions presents an opposite trend for the β nucleated PPR and the β nucleated PPH under the conditions we investigated. For the β nucleated copolymers, the content of β form shows also an opposite tendency with that of γ form with the change of crystallization conditions. The formation of γ form is preferred under lower cooling rates or higher isothermal crystallization temperatures, whereas the amount of β form increased with increasing the cooling rates or decreasing the isothermal temperatures. This opposite tendency could be interpreted in terms of the competition between the β nucleation ability of β nucleating agent and the γ nucleation action of the comonomer defects. The existing comonomer defects that favor the formation of γ form may suppress the nucleation ability of β nucleating agent. A higher proportion of β form in PPR containing a β nucleating agent could be achieved under faster cooling rates or lower crystallization temperatures. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Cross‐linked agarose for separation of low molecular weight natural products in hydrophilic interaction liquid chromatography
Authors: Tan Tianwei , Su Zhi‐Guo , Gu Ming , Xu Jun , Janson Jan‐Christer 
Published: May 2010

AbstractFollowing its market introduction in 1982, the cross‐linked 12% agarose gel media Superose 12 has become widely known as a tool for size exclusion chromatography of proteins and other biological macromolecules. In this review it is shown that, when appropriate mobile phases are used, Superose possesses adsorption properties similar to that of traditional media for hydrophilic interaction liquid chromatography (HILIC). This is illustrated by the separation and purification of low molecular weight compounds such as polyphenols including active components of traditional Chinese medicinal herbs and green tea. Structural features of the cross‐linked agarose that likely cause the observed adsorption effects are discussed aswell. These are identified as being primarily ether bonds acting as strong hydrogen bond acceptors as well as hydrophobic residues originating from the cross‐linking reagents.
Development of a validated LC method for enantiomeric separation and determination of adrafinil and its related substances on a Chiralcel OJ‐H column connected to PDA and polarimetric detectors in series
Authors: Rao R. Nageswara , Maurya Pawan K. , Shinde Dhananjay D. 
Published: May 2010

AbstractA rapid and reliable high‐performance liquid chromatographic method for resolution of enantiomers of adrafinil [(±)‐ADL], a novel vigilance promoting agent, and its synthetic intermediates was developed. The separation was carried out on a Chiralcel OJ‐H using n‐hexane–ethanol (62:38 v/v) as a mobile phase. The detection was carried out at 225 nm using a photodiode array (PDA) detector. The optical rotation and order of elution of enantiomers were assigned. The method is suitable not only for process development of ADL but also for quality assurance of bulk drugs and pharmaceuticals. Copyright © 2010 John Wiley & Sons, Ltd.