bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Pioglitazone vs Glyburide in Early Heart Failure: Insights From a Randomized Controlled Study of Patients With Type 2 Diabetes and Mild Cardiac Disease
Authors: Giles Thomas D. , Elkayam Uri , Bhattacharya Mondira , Perez Alfonso , Miller Alan B.
Published: April 2010

Pioglitazone may cause fluid retention, a well‐known side effect of thiazolidinediones, and may exacerbate heart failure. Patients with type 2 diabetes and mild cardiac disease (New York Heart Association functional class I) received pioglitazone (n=151) or glyburide (n=149) for 1 year. The primary endpoint was change in distance covered in the 6‐minute walk test. Main secondary endpoints included comparison of cardiovascular mortality and morbidity, analysis of changes from baseline in cardiac structure and function by echocardiogram, and lipid panel. There was no significant treatment difference in the mean change from baseline in the 6‐minute walk test (−11.7 m [95% confidence interval, −29.79 to 6.42]). Cardiovascular mortality and morbidity were not significantly different between the treatment groups. Echocardiographic data suggested no significant deterioration in cardiac function with pioglitazone, although more heart failure (10 vs 7 patients), edema (21.2% vs 12.8%), and weight gain (2.56±4.62 kg vs 0.86±3.85 kg) were observed than with glyburide. Congest Heart Fail. 2010;16:111–117. © 2010 Wiley Periodicals, Inc.
Comparative genome‐wide analysis of small RNAs of major Gram‐positive pathogens: from identification to application
Authors: Mraheil Mobarak A. , Billion André , Kuenne Carsten , Pischimarov Jordan , Kreikemeyer Bernd , Engelmann Susanne , Hartke Axel , Giard Jean‐Christophe , Rupnik Maja , Vorwerk Sonja , Beier Markus , Retey Julia , Hartsch Thomas , Jacob Anette , Cemič Franz , Hemberger Jürgen , Chakraborty Trinad , Hain Torsten
Published: April 2010

In the recent years, the number of drug‐ and multi‐drug‐resistant microbial strains has increased rapidly. Therefore, the need to identify innovative approaches for development of novel anti‐infectives and new therapeutic targets is of high priority in global health care. The detection of small RNAs (sRNAs) in bacteria has attracted considerable attention as an emerging class of new gene expression regulators. Several experimental technologies to predict sRNA have been established for the Gram‐negative model organism Escherichia coli. In many respects, sRNA screens in this model system have set a blueprint for the global and functional identification of sRNAs for Gram‐positive microbes, but the functional role of sRNAs in colonization and pathogenicity for Listeria monocytogenes, Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis and Clostridium difficile is almost completely unknown. Here, we report the current knowledge about the sRNAs of these socioeconomically relevant Gram‐positive pathogens, overview the state‐of‐the‐art high‐throughput sRNA screening methods and summarize bioinformatics approaches for genome‐wide sRNA identification and target prediction. Finally, we discuss the use of modified peptide nucleic acids (PNAs) as a novel tool to inactivate potential sRNA and their applications in rapid and specific detection of pathogenic bacteria.
Liparis guangxiensissp. nov. (Malaxideae: Orchidaceae) from China
Authors: Feng Chang‐Lin , Jin Xiao‐Hua
Published: April 2010

A new orchid species,Liparis guangxiensisC. L. Feng & X. H. Jin, is described and illustrated from Guangxi, China. It is a widespread epiphyte in the limestone region at elevations of 200–1400 m in tropical evergreen forest.Liparis guangxiensisis similar toL. rhombeasharing a similar habit, a bifid lip and a column without wings, but differs by having a compressed peduncle, lateral sepals forming in ‘V’ below the lip and an oblong lip with a callus at the base.
GOD IN AN IRRELIGIOUS WORLD
Authors: Bonhoeffer Dietrich
Published: April 2010

Note: The following reflections on the predicament of the Christian Church in the modern world have been taken from the collection of letters which Dietrich Bonhoeffer wrote during his emprisonment and which have been published under the title Widerstand und Ergebung (see Book Reviews). Bonhoeffer intended to develop this theme further and to indicate what consequences the Church should draw from this new situation. But after the events of July 20, 1944, he was brought first to the Prinz Albrechtstrasse, and then to various concentration‐camps, until the end came on April 9, 1944. Thus his task was accomplished when he had raised this fundamental question addressed to the whole Christian Church.
COOPERATION OF MEN AND WOMEN IN CHURCH AND SOCIETY
Authors: Waddams Herbert N.
Published: April 2010

a statement drawn up by the Department on Cooperation of Men and Women in Church and Society which the Central Committee of the World Council decided to commend to the Churches for their study and comment
POVERTY OF DIALOGUE OR DIALOGUE WITH THE POOR
Authors: Niilus Leopoldo J.
Published: April 2010

The major test case for Christian collaboration centres around the rich and poor nations dichotomy.

(THOMAS F. STRANSKY, Church and Society, Geneva 1966, The Ecumenist, Vol. 4, No. 6, Sept.–Oct. 1966.)

When the young man heard this he went away sorrowful; for he had great possessions. (Matthew 19. 22.)
“Not by bread alone…” How does Jesus free and unite us?
Authors: Koyama Kosuke
Published: April 2010

Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil. And he fasted forty days and forty nights, and afterwards he was hungry. And the tempter came and said to him: “If you are the Son of God, command these stones to become loaves of bread.” But he answered: “It is written: ‘Man shall not live by bread alone, but by every word that proceeds from the mouth of God’.” Matt. 4: 1–4.
Ecumenism and Renewal in Brazil: an Appraisal
Authors: Dias Zwinglio M.
Published: April 2010

The ecumenical experience is a call to an experience of renewal, as it makes a challenge for a new form of being‐a‐church to all of the ecclesiastical proposals crystallized over the centuries. For this reason it demands a decisive opening to cultural, political and religious experiences. These do not always correspond to the criteria maintained by the ecclesiastical institutions, but they contain and manifest in their own way the fundamental values of the gospel.
The Struggle for a Blessing. Reflections on Genesis 32:24–31
Authors: Hatzopoulos Athanasios
Published: April 2010

Jacob was left alone; and a man wrestled with him until daybreak. When the man saw that he did not prevail against Jacob, he struck him on the hip socket; and Jacob's hip was put out of joint as he wrestled with him. Then he said, “Let me go, for the day is breaking.” But Jacob said, “I will not let you go, unless you bless me.” So he said to him, “What is your name?” And he said, “Jacob.” Then the man said, “You shall no longer be called Jacob, but Israel, for you have striven with God and with humans, and have prevailed.” Then Jacob asked him, “Please tell me your name.” But he said, “Why is it that you ask my name?” And there he blessed him. So Jacob called the place Peniel, saying, “For I have seen God face to face, and yet my life is preserved.” Then sun rose upon him as he passed Penuel, limping because of his hip. (Gen. 32:24–31, NRSV)
Don Teo's Expulsion: Property Regimes, Moral Economies, and Ejido Reform
Authors: Castellanos M. Bianet
Published: April 2010

Este artículo analiza un caso de expulsión ejidal en Yucatán, México, que demuestra como la propiedad se convierte en un mecanismo de regulación social. La comunidad Maya expulsó a un ejidatario por no cumplir con sus faenas y no mantener su responsabilidad moral hacia su comunidad étnica. En la transición del sistema de tierra comunal hacia la privatización, las ideologías morales que sostienen regímenes de propiedad son tan importantes como las maneras en la que los derechos individuales y colectivos son imaginados y practicados. Este análisis ofrece una crítica de las políticas neoliberales, tal y como la reforma constitucional de la ley agraria de 1992, que intentan imponer un modelo occidental caracterizado por ingresos máximos y responsabilidad individual. Además, aporta una explicación alternativa a favor de la perseverancia de los ejidos ante la reforma constitucional.

Through a case study of an ejido (communal landholding) land eviction in Yucatán, Mexico, this article examines the ways in which land is converted into a socially regulating mechanism. An ejido member was evicted because he failed to fulfill his labor obligations and failed to maintain a moral responsibility toward his community. In the transition from communal land tenure to privatization, the moral ideologies that undergird property regimes matter as much as how individual and collective land rights are imagined and practiced. This analysis offers a critique of neoliberal policies such as ejido reform that attempt to impose a Western model of maximized profit and individual responsibility. It also provides another explanation for the continued existence of ejidos after ejido reform.
The Death of Don Pedro: Insecurity and Cultural Continuity in Peacetime Guatemala
Authors: Offit Thomas A. , Cook Garrett
Published: April 2010

Abstracto: Con enfoque en El Baile de los Monos, el baile‐drama más popular y duradero que se realiza en el pueblo de Momostenango en los Altos Occidentales Mayas de Guatemala, examinamos como la violencia epidémica que ha matado al líder espiritual del baile se ha combinado con la inseguridad económica que ahuyenta a la juventud Momosteca, quienes salen en búsqueda de un futuro económico, para amenazar el papel del baile como asilo cultural para los bailarines y para la comunidad. La amenaza hacia el Baile de los Monos es, en si, emblemático de la amenaza neoliberal a la cultura Maya en Guatemala; mas sin embargo la resistencia de los bailarines y su respaldo continuo en el sistema religioso tradicional entre tantas inseguridades enfrentadas paradójicamente brinda una esperanza perdurable. Esta continuidad indica la flexibilidad y plasticidad de la cosmovisión tradicional Maya. Pero también revela los efectos desnivelados del neoliberalismo en los Altos de Guatemala
Local Narratives of Distress and Resilience: Lessons in Psychosocial Well‐Being among the K'iche' Maya in Postwar Guatemala
Authors: Foxen Patricia
Published: April 2010

En Guatemala, las intervenciones psicosociales son fundamentales para el proceso de reconstrucción posguerra, pero la definición y comprensión de las nociones de angustia y bienestar en las comunidades indígenas sigue siendo problemática. Este artículo propone que, a fin de evitar la victimización o la generalización hacia las cuestiónes de salud mental en épocas de posguerra, tales intervenciones deben tener en cuenta los discursos individuales y de la colectivos sobre la vulnerabilidad y la resiliencia, que están conformadas por las historias y ecologías locales por un lado, y por las mas amplias desigualdades estructurales por otro. Al proporcionar una descripción etnográfica de las fuerzas históricas que han contribuido a la situación social y psicológica en la comunidad k'iche' de Tululché, la autora sugiere nuevas formas de pensar acerca de las conexiones entre violencia, cultura y salud mental en las zonas rurales que siguen en una situación de exclusión social. En particular, ella muestra cómo la acumulación de ambos procesos—procesos traumáticos y procesos de fortaleza—forman parte tanto de la memoria colectiva e individual que de las esperanzas futures, que juntas son la base del bienestar psicosocial.
A Cacophony of Autochthony: Representing Indigeneity in Oaxacan Popular Mobilization
Authors: Norget Kristin
Published: April 2010

Este artículo examina la movilización popular y social en Oaxaca, México a través del ejemplo del movimiento de la Asamblea Popular de los Pueblos de Oaxaca (APPO). Estas páginas se centran en la manera en que el concepto de “indigeneidad” fue utilizado en representaciones e identificaciones de la APPO por diversos actores sociales. Un análisis más profunda de la actual movilización social en Oaxaca, ejemplificado por la APPO, sugiere que el uso de indigeneidad como etiqueta de identidad requiere una perspectivacrítica. Este trabajo argumenta que una dependencia aparente de modos de pensar dicotomizados (por ej., indígena/no‐indígena) nos limita a la hora de revelar los diálogos de identidad dentro de la APPO y otras formas actuales de movilización colectiva a gran escala en Latinoamérica. También obstaculiza el reconocimiento de la extensión y medios con los que las identidades generadas por movilizaciones aquí y más allá son constituidas por una sociedad civil más global (y virtual).

This article examines popular social mobilization in Oaxaca, Mexico, through the example of the 2006 movement of the Asamblea Popular de los Pueblos de Oaxaca (APPO). It focuses on the way the concept of “indigeneity” came to be used in representations and identifications of the APPO by various social actors. A deeper examination of current social mobilization in Oaxaca as exemplified by the APPO suggests that the use of indigeneity as an identity label should be approached with a more sharply ground critical lens. This work argues that an apparent continued analytical reliance on modes of dichotomized thinking (e.g., indigenous/non‐indigenous) is limiting in terms of revealing the complicated interpellations of identity at play in the APPO and other current forms of large‐scale collective action in Latin America. It also prevents recognition of the extent and ways in which movement identities here and elsewhere are being constituted by an increasingly global (and virtual) civil society.
No Time Lag in the Photoelectric Effect
Authors: Gluck Paul , Saering Bernd
Published: April 2010

The photoelectric effect was discovered in the 19th century by Heinrich Hertz. It is interesting to note that the same scientist showed experimentally the wave nature of light, and thereby vindicated Maxwell's wave theory, and discovered the effect in which light shows corpuscular behavior. This paper describes a simple demonstration, enabling one to show the absence of a time lag in the photoelectric effect to an accuracy of a microsecond.
The Physics of the Imploding Can Experiment
Authors: Mohazzabi Pirooz
Published: April 2010

One of the popular demonstrations of atmospheric pressure in introductory physics courses is the “crushing can” or “imploding can” experiment.1–4 In this demonstration, which has also been extensively discussed on the Internet, a small amount of water is placed in a soda can and heated until it boils and water vapor almost entirely fills the can. The can is then quickly inverted and its opening is allowed to touch the surface of cold water in a container. Upon touching the cold water surface, the can implodes in a fraction of a second as the water vapor in the can condenses.
Einstein's Tea Leaves and Pressure Systems in the Atmosphere
Authors: Tandon Amit , Marshall John
Published: April 2010

Tea leaves gather in the center of the cup when the tea is stirred. In 1926 Einstein1 explained the phenomenon in terms of a secondary, rim-to-center circulation caused by the fluid rubbing against the bottom of the cup. This explanation can be connected to air movement in atmospheric pressure systems to explore, for example, why low-pressure systems tend to be stormy and high-pressure systems are fair weather. Here, following Einstein's lead, we revisit the tea leaf phenomenon, make the connection with atmospheric pressure systems, and describe an illustrative laboratory experiment.
Blue Skies, Coffee Creamer, and Rayleigh Scattering
Authors: Liebl Michael
Published: April 2010

The first physical explanation of Earths blue sky was fashioned in 1871 by Lord Rayleigh.1 Many discussions of Rayleigh scattering and approaches to studying it both in and out of the classroom are available.2–5 Rayleigh scattering accounts for the blue color of the sky and the orange/red color of the Sun near sunset and sunrise, and a number of classroom demonstrations have been described for showing the effects.6–11 This paper describes how these demonstrations can be enhanced by using a spectrometer to measure the preferential scattering of the shorter wavelength light.
Radiological Dispersion Devices and Basic Radiation Science
Authors: Bevelacqua Joseph John
Published: April 2010

Introductory physics courses present the basic concepts of radioactivity and an overview of nuclear physics that emphasizes the basic decay relationship and the various types of emitted radiation. Although this presentation provides insight into radiological science, it often fails to interest students to explore these concepts in a more rigorous manner. One reason for limited student interest is the failure to link the discussion to topics of current interest. The author has found that presenting this material with a link to radiological dispersion devices (RDDs), or dirty bombs, and their associated health effects provides added motivation for students. The events of Sept. 11, 2001, and periodic media focus on RDDs heighten student interest from both a scientific curiosity as well as a personal protection perspective. This article presents a framework for a more interesting discussion of the basics of radiation science and their associated health effects. The presentation can be integrated with existing radioactivity lectures or added as a supplementary or enrichment activity.
The Quark Puzzle: A Novel Approach to Visualizing the Color Symmetries of Quarks
Authors: Gettrust Eric
Published: April 2010

This paper describes a simple hands-on and visual-method designed to introduce physics students of many age groups to the topic of quarks and their role in forming composite particles (baryons and mesons). A set of puzzle pieces representing individual quarks that fit together in ways consistent with known restrictions of flavor, color, and charge are depicted. The employment of the pieces in modeling familiar particles, such as protons and neutrons, as well as other, less familiar hadrons, is shown. Included are notes describing the process of creating the puzzle pieces, followed by some suggestions for their use in educational settings.
Increasing Student Engagement and Enthusiasm: A Projectile Motion Crime Scene
Authors: Bonner David
Published: April 2010

Connecting physics concepts with real-world events allows students to establish a strong conceptual foundation. When such events are particularly interesting to students, it can greatly impact their engagement and enthusiasm in an activity. Activities that involve studying real-world events of high interest can provide students a long-lasting understanding and positive memorable experiences, both of which heighten the learning experiences of those students. One such activity, described in depth in this paper, utilizes a murder mystery and crime scene investigation as an application of basic projectile motion.
Storing the Electric Energy Produced by an AC Generator
Authors: Carvalho P. Simeão , Lima Ana Paula , Carvalho Pedro Simeão
Published: April 2010

Producing energy from renewable energy sources is nowadays a priority in our society. In many cases this energy comes as electric energy, and when we think about electric energy generators, one major issue is how we can store that energy. In this paper we discuss how this can be done and give some ideas for applications that can serve as a motivation for projects with students.
Surface Gravity Waves: Resonance in a Fish Tank
Authors: Sinick Scott J. , Lynch John J.
Published: April 2010

In this work, an inexpensive 10-gallon glass aquarium was used to study wave motion in water. The waves travel at speeds comparable to a person walking (∼1 m/s). The scale of the motion allows for distances to be measured with a meterstick and for times to be measured with a stopwatch. For a wide range of water depths, standing waves were excited by hand using strips of Styrofoam. Several resonant modes were studied starting with the fundamental. Experimental values of wave speed were obtained from measurements of wavelength and period of oscillation. Theoretical values of wave speed were calculated using the surface gravity wave dispersion relation. The agreement between experiment and theory was usually better than 0.5%. The aquarium was a winner in the Apparatus Competition (Low Cost Category) during the AAPT 2006 Summer Meeting at Syracuse University.
The Effect of High School Physics Laboratories on Performance in Introductory College Physics
Authors: Maltese Adam V. , Tai Robert H. , Sadler Philip M.
Published: April 2010

Laboratory experiences play a substantial role in most high school science courses, and many teachers believe the number of labs they offer is a measure of the quality of their curriculum. While some teachers believe labs are meant to confirm concepts taught during lectures, others feel labs should address students' everyday beliefs about the world. Still other teachers emphasize learning of the scientific method and laboratory techniques.1 Accordingly, many articles offer advice on “effective” pedagogical practices.2–5
Physics Is All Around Us
Authors: Greenslade Thomas B.
Published: April 2010

The finale of the weekly physics department seminar series at my college is my annual demonstration lecture. Normally, the front of the room is filled with apparatus, but in May 2008 I had only a giant kaleidoscope1 and a leaning tower of Pisa (Fig. 1) on display. Instead, there was a pile of overhead projector transparencies that showed examples of phenomena and devices that I had seen in my travels. They were largely examples of large-scale, real-world physics that I thought would be useful in starting class discussions. Here are some of them.
An inexpensive LED light sensor
Authors: Kutzner Mickey , Wright Richard , Kutzner Emily
Published: April 2010

Light irradiance measurements are important for students grappling with abstract optical phenomena such as the inverse square law,1 polarization, diffraction, interference, and spectroscopy. A variety of commercial light sensors are available from scientific vendors such as the CI-6504A from PASCO scientific2 and the LS-BTA from Vernier Software and Technology.3 These sensors, in combination with data acquisition interfaces, allow students to digitally record relative irradiances. Many experiments in elementary lab situations, however, do not require this level of sophistication, and a simple LED connected to a voltmeter performs admirably as a readily available and inexpensive photosensor. LEDs are frequently used in the laboratory as light sources,4,5 but their use as photodetectors6,7 is relatively unknown in the physics teaching community. Here we introduce a few of the basic laboratory applications of common LEDs as photosensors.
U–Pb geochronologic constraints on Paleoproterozoic orogenesis in the northwestern Makkovik Province, Labrador, Canada
Authors: Ketchum J. W. F. , Dunning G. R. , Culshaw N. G.
Published: April 2010

A 45 km wide, shear-zone-bounded segment of the northwestern Makkovik Province, Labrador, is underlain by Archean gneisses derived from the adjacent Nain craton. This lithotectonic block (Kaipokok domain) was reworked at high metamorphic grade, overthrust by supracrustal sequences (Lower Aillik and Moran Lake groups), and intruded by granitoid plutons during the Paleoproterozoic. Initial amphibolite-facies reworking of the Kaipokok domain at 1896 ± 6 Ma is indicated by U–Pb ages of metamorphic zircon from a foliated Kikkertavak metadiabase dyke. This is one of the oldest Paleoproterozoic tectonic events dated thus far in northeast Laurentia and may be linked with ca. 1890 Ma plutonism documented elsewhere in the Kaipokok domain. Intrusion of granitoid plutons at [Formula: see text], 1877 ± 5, and [Formula: see text] in the Kaipokok Bay area postdates early thick- and thin-skinned thrusting (possibly east to northeast directed) that involved Lower Aillik Group strata. U–Pb titanite ages of 1866–1847 Ma in part record a metamorphic event that followed this plutonic–tectonic activity. These early events are temporally and kinematically difficult to reconcile with accretion of juvenile Makkovikian terranes in the southeast and may instead be related to early stages of the ca. 1.91–1.72 Ga Torngat orogeny along the western margin of the Nain craton. In contrast, high-grade metamorphism, dextral shearing, and northwestward thrusting between 1841 and 1784 Ma, including crystallization of an Iggiuk granitic vein at 1811 ± 8 Ma, are in accord with accretion of Makkovikian terranes in a dextral transpressional regime (Makkovikian orogeny sensu stricto). Coeval sinistral transpression in the Torngat orogen suggests that both otogenic belts accommodated relative northward tectonic escape of the Nain craton during this interval.
Écoulements glaciaires et déglaciation hâtive (ca 11 ka Bp ?) du nord-est de la péninsule d'Ungava, Québec, Canada
Authors: Bruneau Denis , Gray James T.
Published: April 2010

Studies of the lithological composition and carbonate contents in the till, the glacial striations and the glacial geomorphology allowed the identification of two distinct ice flows at the northeast end of the Ungava Peninsula and in the area of the Hudson Strait. A general northeastward ice flow, from the Ungava Plateau, has marked the overall region. It joined to an eastward ice stream occupying the Hudson Strait that left traces on Charles Island. This ice stream evacuated the Foxe Basin and the Hudson Bay and overlapped to a limited extend the head of the Ungava Peninsula at Cape Nouvelle-France. The thinness of the till associated with the Ungava flow, the presence of perched blocks among which some are pedestal, and the lack of tapered forms suggest the presence of a ice with low content of debris and cold base in some areas. Subsequently to the westward glacial recession from the Hudson Strait, a readvance of the Ungava glacier with northeast-north direction intersected the earlier eastward movement and calved in the strait at the North of Charles Island. New 14C dating by accelerator mass spectrometry on marine mollusks permitted to locate the deglaciation of the plateau margin, between Deception Bay and Cape Nouvelle-France, prior to 8.5 ka BP. Many older dates suggest the possibility of a very early opening of the Hudson Strait, as early as 10.5–11 ka BP. The early deglaciation in some areas could explain the very high levels of the marine limit of the transgression observed at Cape Nouvelle-France. Furthermore, many ages are intersecting the interval of 8.4–8.9 ka BP, making suspicious the chronology of the glacial readvance of Noble Inlet across the Hudson Strait to the east.
Primitive intratransform volcanism at Garrett Transform Fault (East Pacific Rise)
Authors: Hébert R. , Hekinian R. , Bideau D.
Published: April 2010

The paper presents the results of a petrological study of samples collected by submersible from volcanic features that floor the intratransform domain of the Garrett Transform Fault. Most intratransform volcanics are typically highly porphyritic and primitive mid-ocean ridge basalt (MORB) (glasses have Mg# higher than 0.65), whereas most volcanics close to the East Pacific Rise – transform intersection zone are nearly aphyric evolved MORB (glasses have Mg# lower than 0.54). In the intratransform volcanics, phenocrysts and megacrysts are plagioclase and olivine and accessory spinel microphenocrysts in the magnesian lavas, and clinopyroxene and plagioclase in ferrobasalts. Variable mineral chemistry of plagioclase and spinel, chemical disequilibria between these phases and surrounding glass, and resorption features and oscillatory zoning in plagioclase suggest that limited magma mixing occurred during genesis of intratransform MORB. Aluminous- to chromian-spinel compositions are in agreement with melt interactions in small magma pockets. These processes are superimposed on complex partial melting events of a heterogeneous source region underlying the intratransform domain. Generation of most ferrobasalts can be explained by crystal fractionation of primitive MORB. Some ferrobasalts appear to derive from discrete magma bodies, since they are not simply connected to the magnesian tholeiites through fractional crystallization processes.
Structural interpretation of the Midcontinent Rift in eastern Lake Superior from seismic reflection and potential-field studies
Authors: Mariano John , Hinze William J.
Published: April 2010

Integrated interpretations of potential-field and GLIMPCE and industry seismic reflection data in eastern Lake Superior reveal the structural and stratigraphic complexity of the Midcontinent Rift in this region. Projection of the Keweenaw fault into southeastern Lake Superior suggested by early potential-field studies is confirmed by seismic reflection data. Analysis of seismic data in conjunction with aeromagnetic anomalies and regional gravity data also reveals a continuous section of basalt in the footwall of the Keweenaw fault. The lateral dimensions of this section vary along the strike of the rift from the center of the basin towards the southern flank. Spatially extensive anticlinal and synclinal features, reverse faults and related drag folds imaged by the reflection and enhanced potential-field data attest to the influence of a late-stage compressional event in this region. East-northeast trending gradients and displacements associated with observed potential-field anomalies and fault traces mapped at the surface also indicate a degree of accommodation perpendicular to the strike of the rift. These trends parallel the prevalent tectonic grain in the adjacent Archean basement rocks, perhaps suggesting that structures within the rift were in part controlled by preexisting crustal features.
Detailed basin structure and tectonic evolution of the Midcontinent Rift System in eastern Lake Superior from reprocessing of GLIMPCE deep reflection seismic data
Authors: Samson C. , West G. F.
Published: April 2010

Line F of the GLIMPCE deep marine reflection seismic survey has been reprocessed according to a data-dependent strategy aimed at enhancing the fine structural features of the Midcontinent Rift System in eastern Lake Superior. The processing sequence was specially designed to attenuate first-order water reverberations and to reduce the excessive oscillatory character of the basic wavelet. A detailed examination of the final migrated stacked section reveals that, beneath line F, the Midcontinent Rift System is an almost perfectly symmetric syncline. The structure appears to have formed in the beginning by the extrusion of lavas on a horizontal platform subsiding without major deformation. The initial phase was followed by local crustal sagging in the centre. The transition is marked by a major reflector, which is hypothesized to correspond to the boundary between reverse- and normal-polarity volcanics in eastern Lake Superior. Integrating the results of several recent investigations, a five-stage evolutionary scenario is proposed for the Midcontinent Rift System in eastern Lake Superior: (1) onset of extrusive volcanism, (2) platform subsidence, (3) local crustal sagging, (4) deposition of postrift sediments, and (5) tectonic inversion.
Gravity and magnetic models of the Midcontinent Rift in eastern Lake Superior
Authors: Mariano John , Hinze William J.
Published: April 2010

Gravity and magnetic models of the Midcontinent Rift (MCR) in eastern Lake Superior supplement recent structural and stratigraphic interpretations based on the seismic reflection method. An algorithm developed to accommodate spatially varying direction and magnitude of magnetization within a magnetic source is used in both forward and inverse modeling procedures. Structural attitudes of rift-filling basalts derived from seismic reflection sections are used to rotate the Keweenawan remanent magnetization vectors in the direction of deformation. An iterative linear inversion routine calculates magnitudes of induced and remanent magnetizations, as well as normal and reversed polarity basalt flow distributions. The results indicate that the Koenigsberger ratios of these basalts generally range from 1 to 3, which is in agreement with values obtained from rock property measurements. The models also suggest that the greater volume of the Keweenawan basalt section in eastern Lake Superior is reversely polarized and that remanent magnetizations persist to depths of up to 20 km. Our results, supplemented by isotopic and paleomagnetic data, suggest that the vast majority of the basalts predate 1097 ± 1 Ma. A prominent positive magnetic anomaly and a corresponding gravity low strike west across the trend of the rift from the vicinity of Michipicoten Island. These anomalies may reflect a relatively strongly magnetized, felsic igneous body of late-middle to upper Keweenawan in age. Forward gravity models suggest clastic sedimentary rocks up to several kilometers thick overlay the volcanic rocks in localized depressions. Deep crustal seismic data used to constrain gravity models provide evidence of anomalously dense lower crust beneath the MCR.
Three-dimensional magnetic modelling of the Midcontinent Rift beneath central Lake Superior
Authors: Teskey D. J. , Thomas M. D.
Published: April 2010

In 1987, a high-resolution aeromagnetic survey was carried out over Lake Superior as a contribution to the Great Lakes International Multidisciplinary Program on Crustal Evolution (GLIMPCE). The survey complemented a 20 s (two-way travel-time) shipborne seismic survey conducted over five profiles on the lake in 1986, the purpose of which was to study the 1.1 Ga Midcontinent Rift under the lake. Two and one-half dimensional (2.5D) magnetic modelling has demonstrated that the model predicted by the seismic results is compatible with the magnetic anomalies under the assumption that the magnetization is due essentially to a normally polarized upper layer and a reversely polarized lower layer. An approach has been developed and used to extend the model based on GLIMPCE seismic data westwards over the central portion of the lake by shifting the 2.5D model laterally to the adjacent north–south profile, adjusting the node points, and repeating the process until the area is covered. A surface integration was then carried out over the resulting three-dimensional (3D) structure. The modelling was constrained primarily by 8.0 s (two-way traveltime) seismic lines provided by industry, which are capable of defining the upper surface of the normally magnetized layer and the boundary between the normally and reversely magnetized layer. Values for the magnetization strengths and directions of both layers were estimated from published values on the shore and on islands in the lake. The model was adjusted to match the measured field as closely as possible, thus providing an estimate of the topography of the lower surface of the reversely magnetized layer. The final model was found to be compatible with the gravity anomaly pattern and seismic refraction studies. Varying the magnetization of the upper and lower layer within reasonable limits was found to change the absolute value of the maximum depth (48 km) of the model by approximately 10% but not to significantly effect the shape. The 3D modelling program was shown to be useful for studies of this type where continuity along strike is reasonable.
An interpretation of gravity anomalies over the Midcontinent Rift, Lake Superior, constrained by GLIMPCE seismic and aeromagnetic data
Authors: Thomas M. D. , Teskey D. J.
Published: April 2010

Cross sections of the Midcontinent Rift in Lake Superior, derived from GLIMPCE seismic reflection images, provide unprecedented structural details of the rift and a new constraint for modelling associated gravity anomalies. In turn, gravity modelling, constrained also by new high-resolution aeromagnetic data, has permitted critical examination of the seismic models. The latter generate gravity anomalies having limited agreement with observed anomalies when appropriate rock densities are assigned. Good agreement may be achieved, generally, by making comparatively local changes to the models, while retaining their larger-scale attributes. Gravity modelling thus enhances and supports GLIMPCE seismic models.Modifications to seismic models include revisions of initial densities within the geometrical framework of the models, leading to a redefinition of lithologies. For example, in some segments of the rift, mafic volcanics are substituted for Keweenawan sedimentary and sedimentary–volcanic sequences and for Lower Proterozoic sediments, and a felsic igneous body is modelled within a mafic volcanic unit. Positions of some unit boundaries and faults, or segments thereof, have also been modified.Gravity modelling traces the paths of the Keweenaw, Isle Royale, Thiel, Douglas, and Michipicoten Island faults deep into the crust, generally supporting the configurations outlined by seismic images and, thereby, arguments for rift development controlled by growth faults. Modelling also indicates a requirement for large, buried masses of mafic (plutonic?) igneous rocks of presumed Keweenawan age along the northern margin of the rift. This imparts an asymmetry to the rift, with northern and southern margins dominated by plutonic and volcanic igneous rocks, respectively.
Paleogeographic significance of Scaphites depressus in the Kanguk Formation (Upper Cretaceous), Axel Heiberg Island, Canadian Arctic
Authors: Hills L. V. , Braunberger W. F. , Núñez-Betelu L. K. , Hall R. L.
Published: April 2010

The late Coniacian Scaphites depressus Reeside has been found at Glacier Fiord, Axel Heiberg Island, in the Kanguk Formation for the first time. This ammonite find confirms and modifies earlier postulated connections between the Western Interior Seaway and the Sverdrup Basin during the late Coniacian.
Cryostructures in permafrost, Tuktoyaktuk coastlands, western arctic Canada
Authors: Murton Julian B. , French Hugh M.
Published: April 2010

The shape and distribution of ice and sediment within frozen ground constitute its cryostructure. Observations on perennially frozen sediments in the Tuktoyaktuk coastlands enable six cryostructures to be identified: (1) structureless, (2) lenticular, (3) layered, (4) reticulate, (5) crustal, and (6) suspended. These cryostructures can be transitional or composite. Five cryofacies types can also be identified according to volumetric ice content and grain size. They can be grouped into cryofacies assemblages. The utility of the descriptive classification of ice-rich sediments is illustrated from a palaeothaw layer at Crumbling Point.
Sedimentology, stratigraphy, and tectonic implications of a paleo-Proterozoic continental extensional basin: the El Sherana – Edith River groups, Northern Territory, Australia
Authors: Friedmann S. Julio , Grotzinger John P.
Published: April 2010

The ca. 1.83 Ga El Sherana – Edith River basin of Northern Territory, Australia, contains terrestrial sedimentary and volcanic rocks deposited during continental extension or transtension. Braid-plain sandstones and conglomerates, turbiditic sediments, and interbedded mafic and felsic volcanics, including ignimbrites, filled the basin. Alluvial fans and rock avalanche breccias are locally developed. Prebasinal structure controlled antecedent topography and influenced drainage patterns, thickness changes, and facies distribution.Unconformities bound all formations of the El Sherana and Edith River groups, revealed by beveled and incised strata, reversals in paleocurrent trends, sharp discordance in juxtaposed facies, and paleovalleys filled with unique sediments. Scarp-derived sediments are preserved only in a small, transfer-related strike-slip basin within the larger basin environment. Unconformities are regional and are interpreted as time lines throughout the basin. These unconformities developed during regrading of slopes forced by active tectonism, accompanied by syntectonic sedimentation and basin depocenter migration.The El Sherana – Edith River strata overlie older sediments (~2.1–1.88 Ga) of the Pine Creek orogen, which formed during a period of global orogeny related to continental assembly. Development of the El Sherana – Edith River basin began substantially (40–50 Ma) after denudation of the Pine Creek orogen belt, and is related to regional postcollisional extension. This extension is recorded by basin formation, bimodal tholeiitic and alkalic magmatism, and elevated geotherms. Other paleo-Proterozoic basins of northern Australia show a similar history of rift deposition above a fossil compressional belt.
A review of electromagnetic investigations in the Kapuskasing uplift and surrounding regions: electrical properties of key rocks
Authors: Mareschal Marianne , Kurtz Ron D. , Bailey Richard C.
Published: April 2010

Electromagnetic investigations of the Kapuskasing uplift show that the gross electrical conductivity structure of the present crust is subhorizontal (contrary to the lithology as defined by seismic experiments), with increasing conductivity with depth, a feature common to most continental crusts. The current upper crust of the Chapleau block includes zones of reduced resistivity; the near-surface expression of the Ivanhoe Lake cataclastic zone (< 1 km in depth and 600 m in width), with resistivities of a few hundred ohm metres, is typical of fluid infilling weathered rocks. At least two other zones are less resistive (ρ < 12 kΩ∙m) than the typical upper-crustal Chapleau block (> 40 kΩ∙m), these include a subhorizontal layer at ~ 5 km and a subhorizontal to dipping layer at ~ 2 km. The deeper layer is interpreted as imaging deep fluids (porosities > 0.5%) postdating the uplift. The shallower feature, possibly related to the seismically detected detachment zone dipping at ~ 15° could be imaging conductors such as recent fluids or remnants of solid films precipitated at grain boundaries by more ancient fluids.Auger spectrometry of high-grade rocks exposed near the extrapolated surface expression of the shallower conductor reveals that fragments of graphite films (3–30 nm thick) are commonly found at grain boundaries, whereas traces of sulphur and chlorine are relatively rare. The electrical resistivity of these rocks was measured in laboratory and is lower than normally observed for similar high-grade rocks from other parts of the Canadian shield (5–25 kΩ∙m as opposed to 30–100 kΩ∙m).The Kapuskasing Uplift has opened a new area of research on upper-mantle conductivity structure from surface electromagnetic field measurements, an endeavour believed impossible until now.
The geology and structure of the mid-crustal Wawa gneiss domain: a key to understanding tectonic variation with depth and time in the late Archean Abitibi–Wawa orogen
Authors: Moser D. E.
Published: April 2010

The amphibolite-facies central Wawa gneiss domain (CWGD) preserves structures that developed at the mid-crustal level of the ca. 2.7 Ga Abitibi–Wawa orogen in the southern Superior Province. The relative ages of these domainal structures are documented and brackets on their absolute ages established using existing U–Pb age data. Correlation of tectonic events within the CWGD, and comparison of these events with the evolution of other structural levels of the orogen, has led to subdivision of orogenesis into five stages. During stage 1 (2700–2680 Ma), 2.9 and 2.7 Ga rocks were tightly folded and (or) thrusted at all crustal levels in at least one thick-skinned compression event. During stage 2 (2680–2670 Ma), folding and thrusting of Timiskaming-age sediments at high levels of the orogen was thin-skinned and had no effect on CWGD gneisses. During stage 3 (2670–2660 Ma), while the upper crust was relatively stable, a 1 km thick package of volcanics and sediments, the Borden Lake belt, was underthrust northwards to depths of 30 km and in-folded with orthogneiss of the CWGD. During stage 4 (2660–2637 Ma), coeval east–west extension and granulite metamorphism of the middle crust produced gently dipping shear zones that overprinted earlier fold structures in the CWGD and lower structural levels of the orogen. This took place with minimal effect on the upper crust. Stage 5 (2630–2580 Ma) marks a period of east–west shortening and (or) fault reactivation in the Kapuskasing uplift and upper-crustal greenstone belts that allowed penetration of deep-crustal metamorphic fluids into the latter. In general, analysis of the structural evolution of the CWGD indicates that deformation and metamorphism in the middle crust of the Abitibi–Wawa orogen outlasted that at upper-crustal levels, resulting in the generally shallower dips of planar fabrics in the deeper structural levels of the Kapuskasing uplift crustal cross section.
U–Pb zircon and monazite ages from the Kapuskasing uplift: age constraints on deformation within the Ivanhoe Lake fault zone
Authors: Krogh T. E. , Moser D. E.
Published: April 2010

A decade of U–Pb dating of zircon and monazite from high-grade metamorphic rocks in the Kapuskasing uplift has identified a series of magmatic and metamorphic events between 2700 and 2585 Ma, and indicates that the onset of regional granulite metamorphism took place at mid-crustal levels of the southern Superior craton ca. 2660 Ma. New U–Pb ages for zircon and monazite have been used to constrain the age of ductile deformation fabrics at two sites in the Ivanhoe Lake fault zone, the structure along which the granulite-facies Kapuskasing structural zone was uplifted. These results suggest that the fault zone was probably active in the late Archean (as young as 2630 Ma) and again at approximately 2500 Ma.
Crustal geochemistry in the Wawa–Foleyet region, Ontario
Authors: Shaw D. M. , Dickin A. P. , Li H. , McNutt R. H. , Schwarcz H. P. , Truscott M. G.
Published: April 2010

Fifty-three rock samples from the Kapuskasing structural zone (KSZ) and 56 from the Wawa domal gneiss terrane (WGT), Ontario, have been analysed for major elements, 32 trace elements, and δ18O; δD was measured in a few samples.Average chemical compositions for the KSZ and WGT regions have been calculated from map unit averages weighted by regional abundance. Compared with estimates of the composition of the upper continental crust (UCC), the KSZ is enriched in Al, Fe, Mg, Ca, P, transition elements, Sc, and Sr; depleted in Si, B, most rare earth elements, Zr, Hf, Nb, Ta, Li, Na, K, U, Th, Ba, and Rb; but similar in composition to estimates of the lower continental crust. The WGT is closer in composition to the UCC. These data support the interpretation, on geophysical and petrological grounds, that the crust here is layered and has been uplifted, the WGT and KSZ regions representing progressively deeper levels.Igneous rock and orthogneiss δ18O values in the KSZ and WGT show good correlation with the weight percentages of SiO2. Paragneisses and clastic sediments and metavolcanics in the Michipicoten greenstone belt have higher ratios, as in other greenstone belts. Low δ18O and high δD values in most of the higher grade mafic gneisses show that they have never undergone low-temperature marine alteration. However, a few mafic gneisses with relict pillows show δ18O and δD values indicating low-temperature aqueous alteration. The δ18O and δD evidence throughout the two regions supports the view that no regional fluid homogenization took place.Errorchron ages of 2725 ± 130 Ma (Rb/Sr) and 2755 ± 110 Ma (Sm/Nd) were obtained for tonalite–granodiorite gneiss and agree within error with results from other workers. The intrusive Floranna Lake complex is 2580 ± 120 Ma (Rb/Sr), not significantly different from the age of the tonalite. Scatter in the data is to be attributed to localized late-stage alteration under low water–rock ratios by Sr-rich–Rb-poor brines. Model Nd ages suggest that there is no old crust [Formula: see text] in the region and that the 2700 Ma mantle was depleted relative to the bulk earth.