bluuebunny/crossref_metadata_2025 huggingface dataset:
High Resolution Radiocarbon Dating at the Gerstle River Site, Central Alaska
Authors: Potter Ben A. , Reuther Joshua D. , Newbold Bradley A. , Yoder David T.
Published: April 2012

Early Holocene cultural material at Gerstle River, central Alaska, provides excellent contextual controls for examining variability in radiocarbon dating. Over 4,000 bone and teeth fragments are directly associated with over 7,000 lithic artifacts and 10 discrete charcoal-rich hearths in a thin occupation layer (∼10 cm vertical thickness) within well-stratified loess deposits. Radiocarbon dating of the hearth features indicates overlapping ages at 2σ, suggesting contemporaneity. This study uses the high level of resolution at Gerstle River to evaluate systematic radiocarbon variation due to different materials (collagen and charcoal), different pretreatments of collagen (regular and ultrafiltered), and interlaboratory variation through paired bone and hearth charcoal dates, split samples, and cross-checks. Accurately dating bone collagen is important given the closer association of dated samples with human activities (e.g., butchering) compared with charcoal fragments in certain contexts (e.g., driftwood, paleosols, or alluvial deposits). This study demonstrates the efficacy of bone collagen dating with ultrafiltration to counter potential site-specific contamination. These results also indicate that even in high-resolution situations with little evidence for old-wood effect and contamination, considerable variability can exist among cross-check and even split samples from single pieces of charcoal from short-lived species.
Craft Specialists at Moche: Organization, Affiliations, and Identities
Authors: Bernier Hélène
Published: April 2012

This article examines the organization of specialized craft production at the urban site of Moche, known as the capital of the Southern Moche state. Recent excavations in workshop contexts revealed that the urban population of Moche was in part composed of ceramists, metallurgists, and lapidaries. These craft specialists played a significant role in the economic, political, and religious spheres of the Moche polity. Data obtained during excavations of workshops and domestic compounds are used to analyze the context, scale, and intensity of craft production, taking into account the nature of the goods produced and the identity of consumers. The discussion also considers the integration of craft specialists into the daily life and social structure at the site of Moche. Excavations showed that while urban craft specialists were not independent, they were not tightly controlled by a centralized ruling elite. They produced symbolic goods in various small to middle-scale workshops integrated into residential units, under the direct authority of urban leaders taking advantage of this particular organization of semi-attached craft production in various status-building strategies.
Continuity and Transformation During the Terminal Middle Horizon (A.D. 950–1150): A Bioarchaeological Assessment of Tumilaca Origins within the Middle Moquegua Valley, Peru
Authors: Sutter Richard C. , Sharratt Nicola
Published: April 2012

Previous archaeological studies suggest that terminal Middle Horizon Tumilaca populations (cal A.D. 950–1150) of the middle Moquegua Valley represent direct descendants of earlier Chen Chen-style Tiwankau colonists of the region. This study tests this idea by comparing dentally derived biodistance analyses of Tumilaca, Chen Chen-style, Tiwanaku, and other regional samples. The results indicate that the Tumilaca and Chen Chen-style mortuary samples are similar to one another suggesting that these populations might share an ancestral-descendant relationship. The phenetic relations of the Tumilaca and Chen Chen to other regional samples are also discussed.
Cerro Lampay: Architectural Design and Human Interaction in the North Central Coast of Peru
Authors: Vega-Centeno Rafael
Published: April 2012

Recent fieldwork concerning the late Preceramic/late Archaic period on the PeruvianNorth-Central Ccoast has revealed the existence of large architectural complexes, which scholars interpret as indicative of social complexity. This article is especially concerned with architectural design as an effective means to define social and political organization at Cerro Lampay. It concludes that there was not a highly formalized hierarchy but that power positions within the community could have been negotiated through ritual practices that included the dual organization of participants. It is highly probable that the residents of the North Central Coast were in constant and intense interaction during the late Archaic, which may have resulted in displays of competitive emulationin ritual settings.
Lecturas estratigráficas: arquitectura funeraria y depositación de residuos en el sambaquí Jabuticabeira II
Authors: Villagran Ximena Suarez , Klokler Daniela , Nishida Paula , Gaspar Maria Dulce , DeBlasis Paulo
Published: April 2012

Sambaquís (concheros o shell mounds) son construcciones antrópicas que aperecen en la costa brasileña hace aproximada mente 8000 años erguidas a partir de la acumulación formal de valvas de moluscos. En el Estado de Santa Catarina, algunos sitios tienen la particularidad de presentar un depósito ictiológico superior con características estratigráficas y composicionales semejantes al depósito malacológico (conchero) subyacente. La aparición del depósito superior fue tradicionalmente asociada a cambios en la subsistencia de estos grupos, con el reemplazo del consumo de moluscos por peces. Sin embargo, análisis faunísticos indicaron que la pesca siempre fue una actividad de subsistencia predominante. Nuevas interpretaciones del fenómeno sugirieron que la substitución de valvas de molusco por huesos de pescado responde a alteraciones tardías en la funcionalidad de los sitios. En este trabajo, la micromorfología de depósitos arqueológicos fue aplicada como herramienta principal de análisis para descifrar la formación del sitio Jabuticabeira II. A partir de la combinación de estudios geoarqueológicos, microestratigráficos y arqueofaunísticos realizados en ambos depósitos, proponemos un modelo para la formación de este sambaquí como resultado de sucesivos procesos de depositación antrópicos asociados a actividades rituales. Estos procesos envolvieron la quema de materiales, acumulación y re-depositación como diferentes etapas en el ritual funerario del grupo constructor. El origen de los materiales constructivos es discutido desde un abordaje contextual a través de la valorización del papel simbólico que la depositación de residuos tuvo entre estas poblaciones.
Inka Sacrifice and the Mummy of Salinas Grandes
Authors: Besom Thomas
Published: April 2012

In the last 25 years, materials from some human sacrifices that the Inkas carried out on high mountains (e.g., Aconcagua and Llullaillaco) have been thoroughly analyzed and adequately interpreted. Remains from immolations that took place in other contexts, however, which tend to be poorly preserved and incompletely studied, are not as well understood. In this article, I begin to remedy this imbalance in our knowledge by discussing the sacrifice from Salinas Grandes, which is a salt flat situated in northwestern Argentina. I describe the body of the victim—who was very likely aqhapaq hucha, a specially chosen child—and his clothing, accouterments, and hairstyle. I offer hypotheses on where he came from and on the reasons behind his ritual dispatch. I demonstrate how the different items that were buried with him all contributed to the meaning of his immolation. I also show how the lords of Cuzco may have employed the sacrifice to tie the region where the salt flat is located to the empire.
The La Tolita—Tumaco Culture: Master Metalsmiths in Gold and Platinum
Authors: Scott David A.
Published: April 2012

The archaeological setting of the La Tolita—Tumaco culture is briefly discussed as a framework for the examination of the metallurgy of the area, in particular the gold—platinum alloys used to make platinum-coated gold objects, platinum—gold sintered alloys, and platinum—gold foil—plated objects. The sophisticated approach to the manipulation of metallic materials resulted in several notable advances being made by the La Tolita—Tumaco culture: the production of extremely fine rectangular wire, bimetallic tumbaga alloys, small lead spheres inlaid with platinum, soldering, granulation, and a degree of sophistication to metalworking that is very impressive and, in some cases, unique in the world. Some selected examples are discussed, and the microstructure of a representative selection of the La Tolita material, bimetallic tumbaga construction, the initial sintered gold—platinum product, platinum-plated gold, and heavily worked gold—platinum composite artifacts are presented.
People Who Lived in Stone Houses: Local Knowledge and Social Difference in the Classic Maya Puuc Region of Yucatan, Mexico
Authors: Carmean Kelli , McAnany Patricia A. , Sabloff Jeremy A.
Published: April 2012

This study builds on the premise that local knowledge of limestone—and its workable characteristics—was foundational to landscape inhabitation in the Puuc region of Yucatán, México. Classic Maya architecture of the northern Yucatán generally is considered to represent the apogee of Maya construction prowess with extensive use of core-veneer masonry and the creation of tall, wide corbelled vaults. Less commonly discussed is the variable distribution of high-quality limestone across the Yucatán, the social matrix that undergirds the quarrying, transporting, and working of limestone, and the pronounced social differences materialized in stone architecture. This study explores these three topics by bringing to bear Yucatec Mayan linguistic evidence and excavation data from the archaeological site of Sayil, in the hilly Puuc region of Yucatán. That information provides a basis for understanding the development of a sprawling residential complex, the role that variable limestone quality played in its expansion, and serves as an index of intra-compound social difference. Late additions to the dwellings indicate that recognition of the cultural value of carved stone persisted long after masonry skills became attenuated. The durability of stone renders it a particularly effective—if underutilized—medium for interpreting social landscapes of the past.
Ritual among the Masses: Deconstructing Identity and Class in an Ancient Maya Neighborhood
Authors: Blackmore Chelsea
Published: April 2012

Equating a single cultural group to a classificatory scheme has implications for not only how archaeologists develop the concept of cultural identity but how we investigate and theorize about internal social dynamics within that same society. For the ancient Maya, social organization remains largely understood as a two-class system—that of commoner and elite. While these categories reflect the extreme ends of known social strata, they inadequately characterize the reality of day-to-day interactions. This has led to tacit assumptions that commoners did not participate in or comprehend the political and social complexity of the world around them. This paper examines how occupants of a Late Classic Maya neighborhood employed ritual and public practices as a means of social differentiation. Excavations at the Northeast Group, part of the ancient Maya site of Chan, Belize, identified considerable diversity between households, suggesting that occupants shaped status and identity through the control and centralization of ritual. Understanding how people distinguished themselves within the context of a neighborhood provides direct evidence of class complexity, challenging traditional models of commoner behavior and more importantly the role they played in ancient Maya society as a whole.
Formation of a Complex Polity on the Eastern Periphery of the Maya Lowlands
Authors: Prufer Keith M. , Moyes Holley , Culleton Brendan J. , Kindon Andrew , Kennett Douglas J.
Published: April 2012

This paper pursues the application of a central tenet of the dual-processual framework, the corporate/network continuum, to the development of Uxbenká, a small monument-bearing polity in the southern Maya Lowlands. During its growth, Uxbenká underwent a transformation from a small farming community to a complex polity with many of the trappings of elite authority that characterizes Classic Maya centers. It was one of the earliest complex polities to develop on the southeastern periphery of the Maya lowlands during the Early Classic period (A.D. 300—600). The polity was founded upon earlier agricultural communities that are now known to extend back to at least A.D. 100. Starting after A.D. 200 the location of the original agricultural village (Group A) was leveled and reorganized to form a public monument garden and the center of political authority throughout much of the Classic period (A.D. 400—800). In this article we present radiocarbon ages from well-defined stratigraphic contexts to establish a site chronology. Based on these data we suggest that by A.D. 450 Uxbenká was the center of a regional political system connected to some of the larger polities in the Maya world (e.g., Tikal). We argue that at this time Uxbenká underwent a significant change from a polity organized by a corporate inclusionary form of ruler-ship to a more networked one marked by exclusionary authority vested in elites who privileged their ancestral relations and network interactions across the geopolitical landscape.
Urns, Bowls, and Ollas: Pottery-Making Practices and Technical Identity in the Southern Andes During the Late Period (ca. A.D. 900—A.D. 1450) (Catamarca, Northwestern Argentine Region, Argentina)
Authors: De La Fuente Guillermo A.
Published: April 2012

This paper presents studies and discussions of pottery-making practices during the Late period (ca. A.D. 900—1450) in Northwestern Argentina. It stems from an extensive archaeological research project carried out in the middle sector of the Abaucán Valley, Province of Catamarca, Argentina. Pottery production during this period is evaluated through the study of technological choices and technical identity, as well as its relationship to the technical behaviors developed by potters. The analysis of a large sample of ceramic sherds, complete vessels, and overfired sherds indicates that the potters produced a very narrow repertoire of ceramic forms (bowls, urns, and ollas) using local raw materials and technology, the latter with a strong hold in the area. Pottery production during the Late period was carried out in household contexts, becoming increasingly intensified and concentrated with the appearance of Inkas in the region. Additionally, some ideas are discussed concerning the technological choices of ancient potters during this period, and the implications for technological studies in archaeological ceramics.
The Square-Room Unit as an Emblem of Power and Authority within the Initial Period Sechín Alto Polity, Casma Valley, Peru
Authors: Pozorski Shelia , Pozorski Thomas
Published: April 2012

Some 3,500 years ago, the Sechín Alto Polity built large, precisely planned cities, one of which contained the largest structures in the New World at that time. Such accomplishments reflect strong, enduring leadership, and we propose that the power and leadership role of these leaders was tangibly manifested by a unique, widely used architectural element and by a related symbol within polity iconography. The distinctive architectural form is a free-standing module that is omnipresent in power loci: temple, palace, storehouse, mid-level administrative buildings, roadside structures, and a satellite site. We also interpret recurring symbols within Sechín Alto Polity iconography as more abstract representations of this architectural form in its capacity as a power symbol. The essence of this "architecture of power" transcended time as the modular form was imitated by a subsequent polity.
Death and Religion in the Southern Moche Periphery: Funerary Practices at Huambacho, Nepeña Valley, Peru
Authors: Chicoine David
Published: April 2012

This article explores religion, death, and mortuary practices in the Southern Moche (A.D. 1-800) periphery as viewed through the excavation of grave contexts at the site of Huambacho, Nepeña Valley, Peru. Moche influence reached Nepeña as is visible in the construction of religious buildings at the site of Pañamarca and the presence of Moche style ceramics at several sites. In 2003 and 2004, scientific excavations at Huambacho, an Early Horizon center mainly built and occupied during the first millennium B.C., yielded a series of intrusive graves containing Gallinazo, Virú, and Moche style objects. This contribution contextualizes these discoveries and focuses on the analysis of funerary patterns of burial, osteological evidence, and symbolic meanings with the objective of understanding local funerary practices and Moche religious and cultural expressions. Symbolic references to coast-highland interactions, inversions in body positioning, and possible human sacrifices bring insights into the complex and potentially tense sociohistorical cirmcumstances in Nepeña during the Moche phase.
Consumo Antropico de Pequeños Mamiferos en el Holoceno de Argentina Central: Perspectivas desde el Abrigo Rocoso Quebrada del Real 1 (Pampa de Achala, Cordoba)
Authors: Medina Matías , Rivero Diego , Teta Pablo
Published: April 2012

Se estudiaron los restos de micromamíferos y otros pequeños vertebrados (Número de Especímenes Identificados = 2,754) del sitio arqueológico Quebrada del Real 1, provincia de Córdoba, Argentina. Las muestras analizadas estuvieron dominadas por roedores caviomorfos de las familias Caviidae y Ctenomyidae, incluyendo taxones de tamaño relativamente grande (200—700 g), hábitos coloniales o gregarios, ubicación predecible, y fáciles de explotar como recurso. El estudio tafonómico de los restos sugiere que las acumulaciones tienen un origen mayoritario en actividades antrópicas de consumo. Las evidencias incluyen la presencia de huellas de corte (especialmente en mandíbulas y huesos del esqueleto apendicular) y un patrón diferencial de alteración térmica, mayormente restringido a las porciones distales de tibias. En el contexto regional, el consumo de pequeños vertebrados sugiere que la implementación de una dieta de amplio espectro posiblemente no sea un proceso arqueológico exclusivamente tardío, sino que se remonta al menos al límite Holoceno Medio-Tardío (ca. 3000 a.P.).
The Color of Influence: A Provenance Study of Hematite-Based Paints on Early Olmec Carved Pottery
Authors: Backes Clarus J. , Cheetham David , Neff Hector
Published: April 2012

Recent research and debates regarding the origin and spread of Olmec iconography during the Early Formative have centered on provenance and stylistic analyses of carved and incised pottery. Studies by instrumental neutron activation analysis (INAA) have indicated that Gulf Coast-style carved-incised pots were exported extensively from the area of the first Olmec capital, San Lorenzo, to several other regions of Mesoamerica. More recently, excavations at the Pacific Coast site of Cantón Corralito have shown that carved-incised pottery and other Olmec-style artifacts dominate strata contemporary with Early Olmec, suggesting the site may represent a settlement enclave of Gulf Olmec peoples. In this study we provide additional evidence of exchange between the Gulf Olmec and the Pacific Coast region by using laser ablation time-of-flight inductively coupled plasma mass spectrometry (LA-TOF-ICP-MS) to characterize hematite-based paints on Olmec-style pottery from Cantón Corralito, and to compare these paints to raw hematite recovered from Cantón Corralito and San Lorenzo. When examined in combination with sherd provenance data, the LA-TOF-ICP-MS data demonstrate that Olmec vessels were decorated in the San Lorenzo region before being exported to the Pacific Coast, and that Gulf Coast hematite was exported to Cantón Corralito, where it was used to enhance Olmec-style symbolism on locally produced vessels.
Photochemistry
Authors: Pfoertner Karl‐Heinz , Oppenländer Thomas
Published: April 2012

The article contains sections titled:1.Introduction2.Primary Photophysical Processes2.1.The Laws of Photochemistry2.2.Quantum Yield3.Performance of Photochemical Reactions3.1.Photoreactor Design3.2.Light Sources3.3.Materials3.4.Scale‐up and Scale‐down (Micro‐Photoreactors)3.5.Economic Considerations4.Light‐Induced Chain Reactions4.1.Photohalogenation4.2.Photosulfochlorination4.3.Photosulfoxidation4.4.Type I Photooxidation4.5.Photopolymerization5.Quasi‐Stoichiometric Photoreactions5.1.Photonitrosation5.2.Photosynthesis of Previtamin D5.3.Photoreactions in Supercritical Fluids6.Photosensitized Reactions6.1.(E/Z)‐Isomerization of Tachysterol6.2.Type II Photooxidation7.Selected Useful Photoreactions7.1.Enamide Cyclization7.2.Cyclobutane Formation7.3.Oxetane Formation7.4.Oxadi‐π‐Methane Rearrangement7.5.1,3‐Dipolar Cycloaddition8.Environmental Applications8.1.Advanced Oxidation Technologies (AOTs)8.2.Photocatalysis8.3.UV‐Disinfection
Polyoxymethylenes
Authors: Haubs Michael , Kurz Klaus , Sextro Guenter
Published: April 2012

The article contains sections titled:

1.

Introduction

2.

Physical and Chemical Properties

2.1.

Morphology

2.2

Mechanical Properties

2.3.

Thermal Properties

2.4.

Chemical Stability

2.5.

UV and Weather Resistance

2.6.

Permeability

2.7.

Fire Behavior

2.8.

Optical Properties

2.9.

Electrical Properties

3.

Production

3.1.

Polymerization of Formaldehyde and Trioxane

3.2.

Homopolymers

3.3.

Copolymers

3.3.1.

Polymerization of Trioxane

3.3.1.1.

Initiation

3.3.1.2.

Chain Propagation

3.3.1.3.

Chain Termination by Chain Transfer

3.4.

Additives

3.4.1.

Stabilizers

4.4.2.

Nucleation Agents

3.4.3.

Release Agents

3.5.

Impact‐Resistant Types

3.6.

Low VOC‐Grades

3.7.

High Strength POM Copolymer

4.

Economic Aspects

5.

Quality Specifications and Analysis

6.

Product Range and Processing

7.

Uses

8.

Recycling

9.

Toxicology and Occupational Health
Antipsychotics
Authors: Kleemann Axel
Published: April 2012

The article contains sections titled:1.Introduction2.Phenothiazines2.1.Phenothiazines with Aliphatic Side Chains2.2.Phenothiazines Substituted by Piperazines2.3.Phenothiazines Substituted by Piperidines3.Butyrophenones4.Indole Derivatives5.Thioxanthene Derivatives6.Diphenylbutylpiperidine Derivatives7.Diazepines, Oxazepines, and Thiazepines8.Sulfonylbenzamide Derivatives9.Other Antipsychotics
Zeolites
Authors: Broach Robert W. , Jan Deng‐Yang , Lesch David A. , Kulprathipanja Santi , Roland Eckehart , Kleinschmit Peter
Published: April 2012

The article contains sections titled:1.Introduction2.Nomenclature3.History4.Structure, Composition, and Properties4.1.Framework Structure4.2.Nonframework Cations4.3.Chemical and Physical Properties4.3.1.Physical Properties4.3.2.Chemical Properties5.Characterization6.Occurrence, Mining, and Processing of Natural Zeolites7.Production of Synthetic Zeolites7.1.Chemistry of Zeolite Synthesis7.2.Composition of Reaction Mixtures7.3.Raw Materials7.3.1.Synthesis Conditions7.3.2.Examples of Industrial Zeolite Syntheses7.3.3.Post Synthesis Treatments7.3.4.Environmental Aspects8.Commercial Applications and Importance8.1.Natural Zeolites8.2.Synthetic Zeolites8.2.1.Adsorption8.2.2.Membranes8.2.3.Catalysis8.2.4.Other Uses9.Toxicology

Zeolites are hydrated aluminosilicates with a three‐dimensional framework structure constructed of SiO4and AlO4tetrahedra linked through oxygen atoms. They contain regular channels or interlinked voids whose aperture diameters are in the micropore range. The regular nature of the channels and apertures, whose dimensions are of the same order of magnitude as molecular diameters, enables the zeolites to function as molecular sieves and gives them value as selective adsorbents for separating substances and as shape‐selective catalysts. This article gives an overview of history, structure, properties, occurrence, production, and applications of zeolites.
Nanoscale Ferroelectricity in Crystalline γ‐Glycine
Authors: Heredia Alejandro , Meunier Vincent , Bdikin Igor K. , Gracio José , Balke Nina , Jesse Stephen , Tselev Alexander , Agarwal Pratul K. , Sumpter Bobby G. , Kalinin Sergei V. , Kholkin Andrei L.
Published: April 2012

Ferroelectrics are multifunctional materials that reversibly change their polarization under an electric field. Recently, the search for new ferroelectrics has focused on organic and bio‐organic materials, where polarization switching is used to record/retrieve information in the form of ferroelectric domains. This progress has opened a new avenue for data storage, molecular recognition, and new self‐assembly routes. Crystalline glycine is the simplest amino acid and is widely used by living organisms to build proteins. Here, it is reported for the first time that γ‐glycine, which has been known to be piezoelectric since 1954, is also a ferroelectric, as evidenced by local electromechanical measurements and by the existence of as‐grown and switchable ferroelectric domains in microcrystals grown from the solution. The experimental results are rationalized by molecular simulations that establish that the polarization vector in γ‐glycine can be switched on the nanoscale level, opening a pathway to novel classes of bioelectronic logic and memory devices.
Thinning and Shaping Solid Films into Functional and Integrative Nanomembranes
Authors: Huang Gaoshan , Mei Yongfeng
Published: April 2012

Conventional solid films on certain substrates play a crucial role in various applications, for example in flat panel displays, silicon technology, and protective coatings. Recently, tremendous attention has been directed toward the thinning and shaping of solids into so‐called nanomembranes, offering a unique and fantastic platform for research in nanoscience and nanotechnology. In this Review, a conceptual description of nanomembranes is introduced and a series of examples demonstrate their great potential for future applications. The thinning of nanomembranes indeed offers another strategy to fabricate nanomaterials, which can be integrated onto a chip and exhibit valuable properties (e.g. giant persistent photoconductivity and thermoelectric property). Furthermore, the stretching of nanomembranes enables a macroscale route for tuning the physical properties of the membranes at the nanoscale. The process by which nanomembranes release from a substrate presents several approaches to shaping nanomembranes into three‐dimensional architectures, such as rolled‐up tubes, wrinkles, and the resulting channels, which can provide fascinating applications in electronics, mechanics, fluidics, and photonics. Nanomembranes as a new type of nanomaterial promise to be an attractive direction for nanoresearch.
Conversion of Methanol to Hydrocarbons: How Zeolite Cavity and Pore Size Controls Product Selectivity
Authors: Olsbye Unni , Svelle Stian , Bjørgen Morten , Beato Pablo , Janssens Ton V. W. , Joensen Finn , Bordiga Silvia , Lillerud Karl Petter
Published: April 2012

Liquid hydrocarbon fuels play an essential part in the global energy chain, owing to their high energy density and easy transportability. Olefins play a similar role in the production of consumer goods. In a post‐oil society, fuel and olefin production will rely on alternative carbon sources, such as biomass, coal, natural gas, and CO2. The methanol‐to‐hydrocarbons (MTH) process is a key step in such routes, and can be tuned into production of gasoline‐rich (methanol to gasoline; MTG) or olefin‐rich (methanol to olefins; MTO) product mixtures by proper choice of catalyst and reaction conditions. This Review presents several commercial MTH projects that have recently been realized, and also fundamental research into the synthesis of microporous materials for the targeted variation of selectivity and lifetime of the catalysts.
Simulation-based training and learning curves in laparoscopic Roux-en-Y gastric bypass
Authors: Zevin B , Aggarwal R , Grantcharov T P
Published: April 2012

Background

Ex vivo simulation-based technical skills training has been shown to improve operating room performance and shorten learning curves for basic laparoscopic procedures. The application of such training for laparoscopic Roux-en-ϒ gastric bypass (LRYGBP) has not been reviewed.

Methods

Relevant studies were identified by one author from a search of MEDLINE and Embase databases from 1 January 1994 to 30 November 2010. Studies examining the learning curves and ex vivo training methods for LRYGBP were included; all other types of bariatric operations were excluded. A manual search of the references was also performed to identify additional potentially relevant papers.

Results

Twelve studies (5 prospective and 7 retrospective case series) were selected for review. The learning curve for LRYGBP was reported to be 50–100 procedures. Bench-top laparoscopic jejunojejunostomy, anaesthetized animals and Thiel human cadavers made up the bulk of the reported models for ex vivo training. Most studies were of relatively poor quality. An evidence-based ex vivo training curriculum for LRYGBP is currently lacking.

Conclusion

Better quality studies are needed to define the learning curve for LRYGBP. Future studies should focus on the design and validation of training models, and a comprehensive curriculum for training and assessment of cognitive, technical and non-technical components of competency for laparoscopic bariatric surgery.
Use of a green (bio) solvent – limonene – as extractant and immiscible diluent for large volume injection in the RPLC‐tandem MS assay of statins and related metabolites in human plasma
Authors: Medvedovici Andrei , Udrescu Stefan , David Victor
Published: April 2012

Limonene, considered a green solvent, was successfully used to extract simvastatin, lovastatin, and their hydroxy‐acid metabolites from human plasma samples. The extraction process was followed by the direct injection of a large volume aliquot (100 μL) from the limonene layer into a Zorbax SB‐C18 Rapid Resolution chromatographic column (50 mm length × 4.6 mm i.d. × 1.8 µm d.p.), operated under gradient elution reversed‐phase separation mechanism. Tandem mass spectrometry operated under the multiple reaction monitoring mode was used for detection, providing low quantitation limits in the 0.25–0.5 ng/mL concentration interval. This method was validated and used for quantitation of simvastatin and its hydroxy acid metabolite in incurred plasma samples obtained from two volunteers participating in a bioequivalence study, using lovastatin and its hydroxy analog as internal standards. The results were statistically compared with those produced by means of an alternative RPLC‐tandem MS using protein precipitation with acetonitrile. The quality attributes of the two methods are comparatively discussed. The agreement between the quality characteristics of the two methods and the experimental results obtained on real samples may be considered as a consistent basis for the simultaneous use of limonene as extraction medium and injection diluent for hydrophobic compounds in bioanalytical approaches. Copyright © 2012 John Wiley & Sons, Ltd.
Authenticity as meaning validation: An empirical investigation of iconic and indexical cues in a context of “green” products
Authors: Ewing Douglas R. , Allen Chris T. , Ewing Randall L.
Published: April 2012

Authenticity judgments involve how individuals distinguish what appears to be real versus fake, genuine versus phony. In this investigation, we bring authenticity into the laboratory to assess it in a manner quite different from most extant approaches. Taking a Peircian semiotic view in a context of environmentally conscious consumption, we develop and test a set of hypotheses concerning the effects of indexical and iconic cues to an authentic “green” product meaning. Results suggest that effects of these indicators of authenticity can be induced in a controlled manner with products being assessed as more or less “green” on the basis of particular cue arrangements. Furthermore, the effectiveness of these semiotic cues is moderated by a basic distinction among products. Taken together, the results provide evidence supporting a meaning validation process as the basis of authenticity judgments and suggest new directions for theory building in a domain where there is substantial practitioner interest. Copyright © 2012 John Wiley & Sons, Ltd.
A “modified crossover technique” for vascular access management in high‐risk patients undergoing transfemoral transcatheter aortic valve implantation
Authors: Buchanan Gill Louise , Chieffo Alaide , Montorfano Matteo , Maccagni Davide , Maisano Francesco , Latib Azeem , Covello Remo Daniel , Grimaldi Antonio , Alfieri Ottavio , Colombo Antonio
Published: April 2012

Objectives

To describe results from our “modified crossover technique” for vascular access management during transcatheter aortic valve implantation (TAVI).

Background

Vascular access management remains a major cause of complications following TAVI due to the large bore sheaths required.

Methods

All suitable patients undergoing TAVI in our center, between June and August 2011, underwent our “modified crossover technique,” which enables the passage of a balloon through left radial access and inflation in the proximal iliac to allow percutaneous closure in a clean field.

Results

In total, 15 patients were included: the logistic EuroSCORE was 19.7 ± 12.1% and STS score 5.7 ± 5.6%. The mean therapeutic femoral access site diameter was 8.1 ± 1.0 mm. Ten (66.7%) patients received Edwards SAPIEN™ XT (two using the new E‐sheath) and five (33.3%) patients a Medtronic CoreValve ReValving System® device. The “modified crossover technique” was used successfully in all patients. There were three vascular complications occurring at the therapeutic access site: one rupture of the external iliac artery, one Prostar failure, and one pseudoaneurysm of the right common femoral artery. All complications were successfully treated percutaneously with covered stent implantation via access from the contralateral femoral artery. In view of the balloon inflation from the left radial artery, the complications could be treated in a clean field with minimal blood loss.

Conclusions

Our “modified crossover technique” using the left radial artery as the diagnostic site for balloon inflation appears a helpful adjunct in managing TAVI vascular access sites. © 2012 Wiley Periodicals, Inc.
Complete interventional heart repair of multiple concomitant cardiac pathologies in a staged approach
Authors: Puls Miriam , Seipelt Ralf , Schillinger Wolfgang
Published: April 2012

Objectives and Background

The evidence of multiple percutaneous cardiac procedures in patients with numerous concomitant cardiac pathologies is limited.

Methods and Results

We report on the case of a 90‐year‐old male patient presenting with advanced heart failure because of degenerative aortic valve stenosis and degenerative mitral valve regurgitation. Moreover, significant coronary artery disease and intolerance of anticoagulation in atrial fibrillation were present. The patient was rejected from surgery because of age and frailty and underwent a staged interventional procedure with percutaneous coronary intervention, followed by transfemoral aortic valve implantation with Edwards Sapien XT, percutaneous mitral valve repair with MitraClip, and left atrial appendage closure with Amplatzer Cardiac Plug. The last procedure was complicated by pericardial tamponade necessitating pericardial drainage. Eight weeks later, the patient reported on the absence of dyspnea in activities of daily living and a significant gain in quality of live.

Conclusions

The case demonstrates feasibility of a staged interventional approach in a select high‐risk patient. © 2012 Wiley Periodicals, Inc.
Significance of the structure of data in partial least squares regression predictions involving both natural and human experimental design
Authors: Rinnan Åsmund , Munck Lars
Published: April 2012

When predicting the chemical composition of food samples from near‐infrared spectroscopy using partial least squares regression, deep knowledge of the origin of the information is not present. We are aiming at opening a Pandora's box of how the prediction of protein proceeds in a unique set of chemically diverse barley mutant samples. An external validation of the sources of co‐variation in nature that are exploited by chemometric models would give a framework for manipulating the deciding information to make expensive calibration more economical. The barley samples were supplemented by two designed data sets: one mirroring the coarse composition of the barley samples by mixing six main chemical components and one set where the biological covariance between the six chemical components had been reduced.

The three original data sets give remarkably comparable prediction models, albeit their regression coefficients are quite different. The origin of the prediction ability of the data is elucidated by splitting the natural barley samples into two parts: one based on simulated biology extracted from a set of chemical mixtures, and the residual after the chemistry has been removed from the raw data. As much as 98.1% of the spectral information in the natural barley data is explained through the simulated biology, leaving as little as 1.9% of the spectral information for the unexplained biological variation and noise. However, unexplained biological variation still gives a fair prediction of protein (RMSECV = 1.23 andr2 = 0.80, compared with RMSECV = 0.46 andr2 = 0.97 for the natural data), and it gives a clear principal component analysis separation of the three genotype classes. The results were interpreted by conducting spectral inspection on the origin of the unique covariate patterns appearing in self‐organised biological systems that should motivate researchers and industry to investigate the compressive effect that the model has on the essential deterministic biological data. Copyright © 2012 John Wiley & Sons, Ltd.
An Amine‐Catalyzed Enantioselective [3+2] Cycloaddition of Azomethine Ylides and α,β‐Unsaturated Aldehydes: Applications and Mechanistic Implications
Authors: Reboredo Silvia , Reyes Efraím , Vicario Jose L. , Badía Dolores , Carrillo Luisa , de Cózar Abel , Cossío Fernando P.
Published: April 2012

The catalytic enantioselective [3+2] cycloaddition between azomethine ylides and α,β‐unsaturated aldehydes catalyzed by α,α‐diphenylprolinol has been studied in detail. In particular, the reaction has been extended to the use of 2‐alkenylidene aminomalonates generated in situ as azomethine ylide precursors. These reactions lead to the formation of pyrrolidines containing a 5‐alkenyl side chain with potential for chemical manipulation. Moreover, a detailed and concise computational study has been carried out to understand the exact nature of the mechanism of this reaction and especially the consequences derived from the incorporation of the chiral secondary amine catalyst on the reaction pathway.
Quantifying Homo‐ and Heteromolecular Hydrogen Bonds as a Guide for Adduct Formation
Authors: Delori Amit , Galek Peter T. A. , Pidcock Elna , Jones William
Published: April 2012

An investigation into the predictability of molecular adduct formation is presented by using the approach of hydrogen bond propensity. Along with the predictions, crystallisation reactions (1a–1j) were carried out between the anti‐malarial drug pyrimethamine (1) and the acids oxalic (a), malonic (b), acetylenedicarboxylic (c), adipic (d), pimelic (e), suberic (f), azelaic acids (g), as well as hexachlorobenzene (h), 1,4‐diiodobenzene (i), and 1,4‐diiodotetrafluorobenzene (j); seven (1a to 1g) of these successfully formed salts. Five of these seven salts were found to be either hydrated or solvated. Hydrogen bond propensity calculations predict that hydrogen bonds between 1 and acids a–g are more likely to form rather than the H bonds involved in self‐association, providing a rationale for the observation of the seven new salts. In contrast, propensity of hydrogen bonds between 1 and h–j is much smaller as compared to other bonds predicted for self‐association/solvate formation, in agreement with the observed unsuccessful reactions.
Preparation of Carbohydrate Arrays by Using Diels–Alder Reactions with Inverse Electron Demand
Authors: Beckmann Henning S. G. , Niederwieser Andrea , Wiessler Manfred , Wittmann Valentin
Published: April 2012

Carbohydrate microarrays are an emerging tool for the high‐throughput screening of carbohydrate–protein interactions that represent the basis of many biologically and medicinally relevant processes. The crucial step in the preparation of carbohydrate arrays is the attachment of carbohydrate probes to the surface. We examined the Diels–Alder reaction with inverse‐electron‐demand (DARinv) as an irreversible, chemoselective ligation reaction for that purpose. After having shown the efficiency of the DARinv in solution, we prepared a series of carbohydrate–dienophile conjugates that were printed onto tetrazine‐modified glass slides. Binding experiments with fluorescently labeled lectins proved successful and homogeneous immobilization was achieved by the DARinv. For immobilization of nonfunctionalized reducing oligosaccharides we developed a bifunctional chemoselective linker that enabled the attachment of a dienophile tag to the oligosaccharides through oxime ligation. The conjugates obtained were successfully immobilized on glass slides. The presented strategies for the immobilization of both synthetic carbohydrate derivatives and unprotected reducing oligosaccharides facilitate the preparation of high‐quality carbohydrate microarrays by means of the chemoselective DARinv. This concept can be readily adapted for the preparation of other biomolecule arrays.
Magic Pairs and Structural Transitions in Binary Metallic Clusters
Authors: Cune Liviu‐Cristian
Published: April 2012

Structures and binding energies for bimetallic clusters consisting of a large variety of atomic species are obtained for all atomic sizes N≤40 and all concentrations, using an interatomic potential derived within a quasi‐classical description. It is found that increasing the difference between the two types of atoms leads to a gradual disappearance of the well‐known homo‐atomic geometric magic numbers and the appearance of magic pairs corresponding to the number of atoms of each atomic species in binary nanostructures with higher stability. This change is accompanied by structural transitions and ground‐state↔isomer inversions, induced by changes in composition or concentration. There is a clear tendency towards phase separation, the core–shell radial segregation being predominant (energetically favored) in this model.
The Protonation of Dimethyl Sulfoxide: Spectroscopic Examinations of [(CX3)2SOX]+MF6− (X=H, D; M=As, Sb) and the X‐Ray Structure of [(CH3)2SOH+]4Ge3F164−
Authors: Hopfinger Mathias , Lux Karin , Kornath Andreas
Published: April 2012

Dimethyl sulfoxide (DMSO) reacts with the superacidic solutions of XF/MF5 and XF/GeF4 (X=H, D; M=As, Sb) under formation of the corresponding salts [(CX3)2SOX+]MF6− and [(CH3)2SOH+]4Ge3F164−, respectively. The salts are characterized by vibrational and NMR spectroscopy, and in the case of [(CH3)2SOH+]4Ge3F164− also by single‐crystal X‐ray analysis. The salt [(CH3)2SOH+]4Ge3F164− crystallizes in the monoclinic space group P21/c with two formula units in the unit cell. The crystal structure possesses an unusual anion consisting of a chain of three slightly distorted fluorine‐bridged GeF6 octahedra. The vibrational spectra are compared to the quantum chemically calculated free [(CX3)2SOX+] cations. The described salts are isolated examples of completely protonated DMSO molecules in the condensed phase.
An energy efficient medium access control protocol for target tracking based on dynamic convey tree collaboration in wireless sensor networks
Authors: Wang Yun , Shi Peizhong , Li Kai , Chen Zhikui
Published: April 2012

Collisions and interferences among nodes pose a challenge for data aggregation in many applications, such as target tracking by adopting dynamic convey tree‐based collaboration (DCTC). Because coordination with a time division multiple access (TDMA) medium access control (MAC) might provide an opportunity for better interference control, in this paper, we refine slot allocation to nodes in a dynamic convey tree and design an energy efficient MAC protocol called dynamic‐time division multiple access (D‐TDMA). The D‐TDMA protocol avoids collisions and interferences and allocates contiguous active slots to nodes as far as possible during data aggregation from leaf nodes to a root node. As a result, energy consumption in switching from sleep to active state is saved. In comparison with Always‐On scheme, theoretical analysis results show that the proposed protocol D‐TDMA improves energy efficiency by up to 28.3% during one data aggregation. Furthermore, simulation results show that D‐TDMA does not suffer from collisions and interferences among nodes in a dynamic convey tree and performs similar throughput to that of Always‐On scheme. Because of its advantage of parallel and continuous scheduling among node pairs in the convey tree, D‐TDMA outperforms efficient slot reservation in both energy efficiency and low delay because of to slot saving. Copyright © 2012 John Wiley & Sons, Ltd.
Performance of a Bismuth Bulk Rotating Disk Electrode for Heavy Metal Analysis: Determination of Lead in Environmental Samples
Authors: de la Gala Morales María , Marín Mª Rosario Palomo , Calvo Blázquez Lorenzo , Gil Eduardo Pinilla
Published: April 2012

The bismuth bulk electrode is proposed here for the first time in the rotating configuration (BiB‐RDE) as the electrode of choice for voltammetric analysis of selected heavy metal ions. Optimization of chemical and instrumental parameters was carried out to develop a reliable and convenient method for the determination of Zn(II), Cd(II) and Pb(II) by SWASV. Appropriate detection limits were found for environmental monitoring applications in the medium – low µg/L range. The method was validated for Pb(II) determination by certified reference materials. Successful application to the determination of Pb(II) in samples of fortified rainwater and sewage sludge from a steel industry is described.
Sensitivity analyses of crop yields and changes in climate variables simulated with iGAEZ
Authors: Tatsumi Kenichi , Yamashiki Yosuke
Published: April 2012

The objective of this study is to evaluate the influence that minimum temperature, average temperature, and maximum temperature have on yield when using the iGAEZ model. Simulated yields on each grid cell for 1980–1999, in three leading producers of wheat, rice and maize, were combined with climate datasets to evaluate the relationships between temperature and simulated crop yields. A generalized additive model was evaluated to analyse changes in diurnal temperature range (DTR) and crop yields. Results differ depending on crop and region as to whether there was a clear positive/negative response of yields to daily temperature indices (DTIs) (including DTR, Tmax, Tmin and Tave). However, the effects of DTIs were statistically significant using a generalized additive model for all crops and regions. To evaluate whether future changes in DTIs are relevant for impact assessment, yield responses to projected changes in DTIs by 2080–2099, from 19 climate models under SRES A2, B1 scenarios, were estimated. Among DTIs, DTR changes did significantly affect yield responses in several cases, such as in maize and rice yields in South Asia under B1 scenario. The decreasing/increasing trend of DTIs has an important implication for estimating the future impact of climate changes. Copyright © 2012 John Wiley & Sons, Ltd.