bluuebunny/crossref_metadata_2025 huggingface dataset:
Climate, sediment supply and tectonics as controls on the deposition and preservation of the aeolian-fluvial Etjo Sandstone Formation, Namibia
Authors: MOUNTNEY NIGEL , HOWELL JOHN , FLINT STEPHEN , JERRAM DOUGAL
Published: December 2007

Deposition and subsequent preservation of the Jurassic-Cretaceous Etjo Sandstone Formation of Namibia represents a complex interplay between climatic and tectonic factors and related variations in extrabasinal sediment supply. The aeolian and fluvial deposits indicate semi-arid to arid climatic conditions throughout the deposition of four distinct sedimentary units. The succession records either an upward increase in aridity or an upward increase in aeolian sediment supply, represented by a transition from a fluvially dominated basal unit, through a marginal fluvial-aeolian unit to an exclusively aeolian unit. A combination of inherited palaeotopography and syndepositional extensional faulting provided the space necessary for the accumulation of much of the succession. A basinwide unconformity (super surface) divides the succession. This hiatus resulted partly from a lack of available preservation space and partly from a shutdown in aeolian activity related to a regional climatic reorganization. A subsequent shift in the palaeowind direction from northwesterly to southwesterly exploited sand reserves in the Paraná Basin of South America and led to the resumption of aeolian sedimentation across the region. Variations in preserved bedform thickness were directly controlled by differential amounts of tectonic subsidence across the basin. A second major super surface towards the top of the succession resulted from the regional shutdown of large tracts of the aeolian system following the eruption of Etendeka flood basalts across the region.
The control of sedimentary facies by climate during phases of crustal extension: examples from the Triassic of onshore and offshore England and Northern Ireland
Authors: RUFFELL A. , SHELTON R.
Published: December 2007

Crustal extension controls the tectonic accommodation space available for sediments in rift settings and may be defined by the structural and depositional geometry of sedimentary successions observed on seismic data and the rate of subsidence through time as represented by the accommodation of sediment. The characteristic features of each are dependant on three variables: the time taken for deposition; the interplay between tectonics and eustasy and the lithology (thus facies) of the succession observed. The Sherwood Sandstone Group has been considered to represent a syn-rift phase of fluvial deposition throughout Europe, with the overlying Mercia Mudstone Group interpreted as the succeeding phase of deposition in an evaporitic seaway during post-rift thermal subsidence. More recently, however, there has been the recognition that it is the Mercia Mst Gp which is seen to thicken markedly into faults imaged on seismic data rather than the Sherwood Sandstone Group. This work demonstrates the Mercia Mst Gp to be a syn-rift phase of deposition, with the fine grained nature of the sedimentary record at this time controlled by the prevailing arid climate. Such conditions were not conducive to the large-scale and rapid movement of sediments from the hinterlands raised by relative footwall uplift, thus the sediments are fine grained. The minor thickening of the Sherwood Sst Gp into faults is interpreted to be a combination of minor extension in the early Triassic superimposed on thermal subsidence inherited from the important regional phase of extension in the early Permian. Analysis of the timing of fault growth indicates a larger proportion of fault-controlled, synsedimentary movement occurred during the mid-to-late Triassic (Mercia Mst Gp) rather than the early Triassic (Sherwood Sst Gp).
Distinguishing climatic and tectonic signals in the sedimentary successions of marginal basins using Sr isotopes: an example from the Messinian salinity crisis, Eastern Mediterranean
Authors: FLECKER R. , ELLAM R. M.
Published: December 2007

The evolution of oceanic
87
Sr/
86
Sr through the Tertiary has been sufficiently well documented to provide a useful stratigraphic tool for carbonate-rich marine sediments which were deposited in basins connected to the global oceans. In isolated basins, sea water
87
Sr/
86
Sr will diverge from coeval oceanic values; thus if independent age information exists, the geochemical signature can constrain the timing of isolation. In marginal basins formed in tectonically active settings, the timing of isolation is critical to the assessment of the relative importance of climate or tectonic controls on that event. Previously, isolation has been assumed to coincide with the last occurrence of open marine fauna. However, in an example from the Eastern Mediterranean,
87
Sr/
86
Sr data challenge that assumption and can be interpreted as indicating a protracted period of isolation (
c.
3 Ma), during which time marine conditions prevailed, prior to the Messinian salinity crisis at the end of the Miocene. This allows tectonic and climatic signals to be distinguished, since although convergence of Africa with Eurasia was responsible for isolation of this part of the Mediterranean, it is more likely that later climatic change triggered desiccation.
Evidence for a volcanic rifted margin and oceanic crustal structure for the Falkland Plateau Basin
Authors: BARKER P. F.
Published: December 2007

Marine geophysical data from the western Falkland Plateau show strongly lineated magnetic anomalies and a coincident linear gravity high that identify the southeastern margin of a Falkland Islands block as a volcanic rifted continental margin. Characteristics of onshore and offshore dykes suggest this margin is most probably slightly younger than 190 Ma. Together with these data, seismic reflection profiles and sonobuoy seismic refraction data from the basin province of the Falkland Plateau east of the islands indicate an elevated oceanic origin for the major part of the Falkland Plateau Basin, most probably within the Karoo hotspot province. These conclusions are compatible with, but do not directly indicate the independent rotation of a Falkland Islands block, and closely constrain models of southwest Gondwana evolution.
A Tibetan model for the early Tertiary western United States
Authors: DILEK YILDIRIM , MOORES ELDRIDGE M.
Published: December 2007

A comparative study of the geology of the early Tertiary western United States and the modern Tibetan and Turkish–Iranian Plateaux indicates that these three regions, situated in the hinterland of major orogenic belts, share a common taphrogenic evolutionary path. Both the Tibetan and Turkish–Iranian Plateaux have high mean elevations above sea level (>5 km and 2.0–2.5 km, respectively), have experienced fast uplift and widespread unroofing during the last 10–8 Ma, and are undergoing extension nearly perpendicular to the plate convergence direction. Successive accretionary and collisional events accompanied by significant shortening and underplating during the formation of these plateaux resulted in the generation of overthickened continental crust (>50 km) that is currently in the process of extending. A two-stage magmatism, characterized by widespread calc-alkaline volcanism followed and/or overlapped by bimodal (basaltic to rhyolitic) volcanism, occurs synchronously with crustal extension and thinning. The plateaux in general have an internal (closed) drainage system and are drained by antecedent rivers near their edges. The early Tertiary western US Cordillera displayed similar geological and geomorphic features to those observed in the Tibetan and Turkish–Iranian Plateaux in the aftermath of a prolonged Mesozoic orogeny and underwent an orogenic collapse starting around mid-Tertiary time. A N-trending crustal welt with a maximum thickness of 60 km and an elevation around >3 km formed a highland with alpine flora in the hinterland of the Cordilleran orogenic belt and separated internal drainage basins and saline lakes on the east from major flood plains of antecedent river systems on the west. This highland subsequently became the locus of crustal extension, metamorphic core complex formation, and wide-spread calcalkaline volcanism ('ignimbrite flare-up'). This early stage of orogenic collapse was followed by the Basin and Range extension, characterized by block faulting and bimodal volcanism, starting around 18–16 Ma. The Basin and Range extension and associated subsidence resulted in development of the Great Basin with a mean elevation of 1.5 km above sea level and a crustal thickness of 30 km. Similarities in the post-orogenic evolutionary paths of these three regions indicate that continental lithosphere reacts to overthickening in a consistent way through large-scale crustal remobilization and extensional collapse, regardless of the mode and nature of its orogenic build-up.
Emplacement of the Aya Variscan granitic pluton (Basque Pyrenees) in a dextral transcurrent regime inferred from a combined magneto-structural and gravimetric study
Authors: OLIVIER P. , AMÉGLIO L. , RICHEN H. , VADEBOIN F.
Published: December 2007

Magmatic structure, three-dimensional shape and emplacement mode of the Aya pluton, Variscan Pyrenees, have been studied by combining magneto-structural and gravimetric studies. The Aya pluton displays a fabric, acquired using the anisotropy of magnetic susceptibility technique, comparable to that of several other plutons in the Pyrenees, with shallow-plunging lineations and steep foliations trending E-W and NE-SW, forming an S pattern in map view. Gravity modelling was used to determine the probable root of the pluton, directly below the most basic (gabbro-dioritic) facies. This has a funnel shape, with an E-W-trending elliptical horizontal section and a maximum depth of 3.5 km. These different data demonstrate that this pluton was synorogenically emplaced during the main D2 Variscan tectonic phase, in a dextral transcurrent regime.
Late Variscan strike-slip tectonics between the Teplá-Barrandian and Moldanubian terranes (Czech Bohemian Massif): petrostructural evidence
Authors: PITRA PAVEL , BURG JEAN-PIERRE , GUIRAUD MICHEL
Published: December 2007

In the Variscan Bohemian Massif (Czech Republic), no agreement has been reached on the nature of the relationship between the Teplá-Barrandian and the Moldanubian terranes. However, the Teplá-Barrandian is interpreted as a central segment separating the Moldanubian and Saxothuringian terranes and its position is therefore essential for any reconstruction of this part of the Variscan belt.

Our petrological and structural study in the Domazlice-Klatovy region spans the boundary between the Teplá-Barrandian and Moldanubian terranes. There is no conformity of ductile structures in both domains near their interface and their
P–T
evolution is separate in time. The development of major structures and associated metamorphism in the southwestern part of the Barrandian was accompanied by syntectonic intrusions of granitoid and diorite bodies, dated at about 520 Ma. The Moldanubian migmatites are characterized by a LP-HT metamorphism that possibly took place at about 320 Ma. The metamorphic record of the Barrandian rocks shows no influence of the Moldanubian partial melting. The contacts are marked by semi-brittle to brittle structures: sinistral strike-slip faulting developed in the Central Bohemian Shear Zone, whereas the West Bohemian Shear Zone acted as a semi-brittle normal fault with a dextral component. Both shear zones may be nearly contemporaneous, accommodating a bulk N-S compression. The Central Bohemian Shear Zone was later reactivated in a dextral regime.

Although timing is uncertain, the juxtaposition of both terranes took place probably in the waning stages of the Variscan orogeny, earlier than the late Stephanian. We argue that the late-orogenic (semi)brittle strike-slip tectonics modified considerably the face of the Bohemian Massif and the geodynamic models of the Bohemian Massif have to be reviewed with reference to this essential point.
Regular terrestrially derived palynofacies cycles in irregular marine sedimentary cycles, Lower Lias, Dorset, UK
Authors: WATERHOUSE HELEN K.
Published: December 2007

The Lower Lias of Dorset, England comprises prominent limestone-marl-shale alternations considered to be obliquity orbitally controlled, probably enhanced by diagenesis. Palynofacies analysis, the study of microscopic particulate organic matter in a sediment, identifies six superimposed palaeo-environmental variations through 12 m of this sequence: (1) 90 cm cycles in abundance of terrestrially derived organic particles, (2) 45 cm cycles in abrasion of wood particles, (3) 1.2–1.8 m cycles in shape of wood particles; (4) irregular cycles (20 cm to 5.2 m) in limestone deposition, (5) irregular alternations (50 cm to 2.5 m) in shale-marl deposition and (6) irregular variation in marine phytoplankton abundance. These are interpreted as: (a) obliquity forcing of marine currents, bottom water oxygenation and organic preservation, (b) precessional forcing of rainfall, position of storm wave base and limestone deposition, (c) eccentricity driven shallow marine energy changes preventing limestone deposition, (d) irregular marine processes affecting shale-marl deposition and marine plankton productivity. Thus, three orbital cycles acted simultaneously with different effects on different environments. Palynofacies analysis is a sensitive tool for extracting palaeoenvironmental information, particularly terrestrial variations recorded in marine sedimentary rocks. In addition, it is demonstrated that regular proxy-climatic orbital cycles are preserved within irregular sedimentary sequences.
Rift basin architecture and stratigraphical implications for basement-cover relationships in the Neoproterozoic Grampian Group of the Scottish Caledonides
Authors: SMITH M. , ROBERTSON S. , ROLLIN K. E.
Published: December 2007

A revised and expanded lithostratigraphy is presented for the lower part of the Dalradian Supergroup in the Central Highlands. Stratigraphical correlations combined with lateral facies variations and geophysical studies are used to define a framework of NE-SW-trending marine basins that formed during a major phase of Neoproterozoic rifting. These basins extended rapidly and infilled with up to 5.5 km of turbiditic deposits, later thermal subsidence is indicated by the regional development of shallow marine shelf environments. The margins to these basins are characterized by lateral facies and thickness changes, stratigraphical omission and onlap relationships of both Grampian and Appin group strata onto a basement of predominantly gneissose strata. Whilst there is clear evidence for a stratigraphical and sedimentological break at the base of the Grampian Group there is presently insufficient structural or metamorphic evidence to prove an orogenic unconformity. Geochronological data confirm the presence of Precambrian events in the basement but have yet to do so in the cover.
The significance of the Geal Charn-Ossian Steep Belt in basin development in the Central Scottish Highlands
Authors: ROBERTSON S. , SMITH M.
Published: December 2007

The Geal Charn-Ossian Steep Belt is a major composite synclinal structure cored by an upward-facing Appin Group succession. It is located at the margin of a west-facing sedimentary basin where more than 8 km of Grampian Group sediment was deposited adjacent to an intrabasin structural ‘high’. The ‘high’ comprises mainly gneissose metasedimentary rocks, the Glen Banchor succession, which acted as the basement to the Grampian and Appin group rocks. Major unconformities are recognized at more than one level as the sedimentary basin successions onlapped onto the 'high'. The primary major upright folds and associated slides of the Steep Belt developed when considerable shortening was focused along the basin margin during the Caledonian Orogeny.
The timing and
P–T
conditions of regional metamorphisni in the Central Highlands, Scotland
Authors: PHILLIPS E. R. , HIGHTON A. J. , HYSLOP E. K. , SMITH M.
Published: December 2007

The Central Highlands of the Scottish Caledonides are dominated by a sequence of poly-deformed metasedimentary rocks largely belonging to the Grampian and Appin groups of the Dalradian Supergroup. In the northern part of the area these are separated from a suite of variably gneissose to locally migmatitic rocks by a number of prominent mid-crustal shear zones. The early evolution of the Central Highlands is interpreted in terms of regional (D1–D2) folding and N- to NW-directed thrusting accompanied by kyanite-grade metamorphism
(P=
7.0–8.0 kbar,
T=
500–600°C). The later stages of this event were characterized by continued ductile shearing along the pre-existing shear zones under sillimanite-grade metamorphic conditions (P=4.7–5.9 kbar,
T
=585–695°C). The exact age of this progressive tectonothermal event remains uncertain, however, available geochronological data can be interpreted as indicating an entirely Precambrian age (
c.
840–800 Ma). This questions previously held views of an entirely Caledonian age for deformation throughout the Highlands.
Testing for the presence of a terrane boundary within Neoproterozoic (Dalradian) to Cambrian siliceous turbidites at Callander, Perthshire, Scotland
Authors: TANNER P. W. GEOFF , PRINGLE MALCOLM S.
Published: December 2007

The Southern Highland Group (Dalradian) and Keltie Water Grit Formation, which includes the Lower Cambrian Leny Limestone, form an inverted, 1.4 km thick, largely arenaceous, sequence at Callander. The grits have the same detrital mineralogy throughout, mainly quartz, plagioclase (An
1–3
), muscovite, and biotite. Chlorite formed from detrital biotite during low-grade regional metamorphism (
T
<270°C). There are some vertical changes in major element (but not trace element) chemistry of the grits, and detrital muscovites have a wide, but comparable, range in composition throughout, apart from an influx of Na-rich micas in the Keltie Water Grits.
40
Ar/
39
Ar laser fusion dating of detrital muscovites yields an age spectrum with a peak at 1600–1800 Ma in the Dalradian rocks; similar old ages occur in the Keltie Water Grits but are diluted by ages of 507–886 Ma. We interpret these new data as showing that the rocks were most likely deposited as a single sequence, possibly with a disconformity, in Neoproterozoic to Early Cambrian times, before the onset of Grampian orogenesis in the Early Palaeozoic. No major structural or stratigraphical breaks have been identified and there is no direct evidence for the presence of two separate terranes.
A game-based framework for CTL counterexamples and 3-valued abstraction-refinement
Authors: Shoham Sharon , Grumberg Orna
Published: December 2007

This work exploits and extends the game-based framework of CTL model checking for counterexample and incremental abstraction-refinement. We define a game-based CTL model checking for abstract models over the 3-valued semantics, which can be used for verification as well as refutation. The model checking process of an abstract model may end with an indefinite result, in which case we suggest a new notion of refinement, which eliminates indefinite results of the model checking. This provides an iterative abstraction-refinement framework. This framework is enhanced by an
incremental
algorithm, where refinement is applied only where indefinite results exist and definite results from prior iterations are used within the model checking algorithm. We also define the notion of
annotated counterexamples
, which are sufficient and minimal counterexamples for full CTL. We present an algorithm that uses the game board of the model checking game to derive an
annotated counterexample
in case the examined system model refutes the checked formula.
Cognition in Organizations
Authors: Hodgkinson Gerard P. , Healey Mark P.
Published: December 2007

This article reviews major developments from 2000 to early 2007 in the psychological analysis of cognition in organizations. Our review, the first in this series to survey cognitive theory and research spanning the entire field of industrial and organizational psychology, considers theoretical, empirical, and methodological advances across 10 substantive domains of application. Two major traditions, the human factors and organizational traditions, have dominated cognitively oriented research in this field. Our central message is that the technological and human systems underpinning contemporary organizational forms are evolving in ways that demand greater cooperation among researchers across both traditions. Such cooperation is necessary in order to gain theoretical insights of sufficient depth and complexity to refine the explanation and prediction of behavior in organizations and derive psychologically sound solutions to the unprecedented information-processing burdens confronting the twenty-first century workforce.
Dual-Processing Accounts of Reasoning, Judgment, and Social Cognition
Authors: Evans Jonathan St. B. T.
Published: December 2007

This article reviews a diverse set of proposals for dual processing in higher cognition within largely disconnected literatures in cognitive and social psychology. All these theories have in common the distinction between cognitive processes that are fast, automatic, and unconscious and those that are slow, deliberative, and conscious. A number of authors have recently suggested that there may be two architecturally (and evolutionarily) distinct cognitive systems underlying these dual-process accounts. However, it emerges that (a) there are multiple kinds of implicit processes described by different theorists and (b) not all of the proposed attributes of the two kinds of processing can be sensibly mapped on to two systems as currently conceived. It is suggested that while some dual-process theories are concerned with parallel competing processes involving explicit and implicit knowledge systems, others are concerned with the influence of preconscious processes that contextualize and shape deliberative reasoning and decision-making.
The Education of Dyslexic Children from Childhood to Young Adulthood
Authors: Shaywitz Sally E. , Morris Robin , Shaywitz Bennett A.
Published: December 2007

The past two decades have witnessed an explosion in our understanding of dyslexia (or specific reading disability), the most common and most carefully studied of the learning disabilities. We first review the core concepts of dyslexia: its definition, prevalence, and developmental course. Next we examine the cognitive model of dyslexia, especially the phonological theory, and review empiric data suggesting genetic and neurobiological influences on the development of dyslexia. With the scientific underpinnings of dyslexia serving as a foundation, we turn our attention to evidence-based approaches to diagnosis and treatment, including interventions and accommodations. Teaching reading represents a major focus. We first review those reading interventions effective in early grades, and then review interventions for older students. To date the preponderance of intervention studies have focused on word-level reading; newer studies are beginning to examine reading interventions that have gone beyond word reading to affect reading fluency and reading comprehension. The article concludes with a discussion of the critical role of accommodations for dyslexic students and the recent neurobiological evidence supporting the need for such accommodations.
A Comprehensive Review of the Placebo Effect: Recent Advances and Current Thought
Authors: Price Donald D. , Finniss Damien G. , Benedetti Fabrizio
Published: December 2007

Our understanding and conceptualization of the placebo effect has shifted in emphasis from a focus on the inert content of a physical placebo agent to the overall simulation of a therapeutic intervention. Research has identified many types of placebo responses driven by different mechanisms depending on the particular context wherein the placebo is given. Some placebo responses, such as analgesia, are initiated and maintained by expectations of symptom change and changes in motivation/emotions. Placebo factors have neurobiological underpinnings and actual effects on the brain and body. They are not just response biases. Other placebo responses result from less conscious processes, such as classical conditioning in the case of immune, hormonal, and respiratory functions. The demonstration of the involvement of placebo mechanisms in clinical trials and routine clinical practice has highlighted interesting considerations for clinical trial design and opened up opportunities for ethical enhancement of these mechanisms in clinical practice.
Effects of CMP Slurry Chemistry on Agglomeration of Alumina and Copper Surface Hardness
Authors: Ihnfeldt Robin V. , Talbot Jan B.
Published: December 2007

The influence of common slurry additives on the colloidal behavior of alumina suspensions and the surface characteristics of copper were investigated. The effects of the addition of glycine and H2O2 to aqueous suspensions of alpha-alumina at various pH values were studied by zeta potential and agglomerate size distribution measurements. Depending on the state of copper in solution, alumina agglomerate size was found to either increase or decrease. Nanohardness of 1 µm copper films deposited onto 30 nm Ta on a silicon wafer was measured after exposure to the same slurry solutions and was found to be significantly affected by pH and addition of chemical additives. The agglomeration behavior and hardness measurements suggest that the states of the copper in solution or on the surface are consistent with potential-pH diagrams.
Deficiency of intramuscular ICC increases fundic muscle excitability but does not impede nitrergic innervation
Authors: Huizinga Jan D. , Liu Louis W. C. , Fitzpatrick Amanda , White Elizabeth , Gill Sandeep , Wang Xuan-Yu , Zarate Natalia , Krebs Lynn , Choi Catherine , Starret Tanya , Dixit Devika , Ye Jing
Published: December 2007

The motility of the gastrointestinal tract is generated by smooth muscle cells and is controlled to a large extent by an intrinsic neural network. A gap of ∼200 nm usually separates nerve varicosities from smooth muscle cells, which suggests that direct innervation of the smooth muscle by synapses does not occur. Enteric nerves do make synapse-like contact with proposed regulatory cells, the interstitial cells of Cajal (ICC), which in turn may be in gap junction contact with smooth muscle cells. The role played by ICC in enteric innervation is controversial. Experimental evidence has been presented in vitro for the hypothesis that nitrergic inhibitory innervation is strongly reduced in the absence of ICC. However, in vivo data appear to dispute that. The present report provides evidence that explains the discrepancy between in vivo and in vitro data and provides evidence that inhibitory neurotransmitters can reach smooth muscle cells without hindrance when ICC are absent. The fundic musculature shows increased responses to substance P-mediated innervation and shows marked spontaneous activity, which is consistent with increased muscle excitability.
Active and inactive pools of nNOS in the nerve terminals in mouse gut: implications for nitrergic neurotransmission
Authors: Rao Y. Manjula , Chaudhury Arun , Goyal Raj K.
Published: December 2007

Nitric oxide (NO) is responsible for nitrergic neurotransmission in the gut, and its release is dependent on its de novo synthesis by neuronal nitric oxide synthase (nNOS). The magnitude of NO synthesis and release during neurotransmission may be related to the fraction of catalytically active nNOS out of a larger pool of inactive nNOS in the nerve terminals. The purpose of the present study was to identify catalytically active and inactive pools of nNOS in the varicosities from mouse gut. Enteric varicosities were confirmed as nitrergic by colocalization of nNOS with the nerve varicosity marker synaptophysin. Low-temperature SDS-PAGE of these varicosity extracts showed 320-, 250-, and 155-kDa bands when blotted with anti-nNOS1422–1433and 320- and 155-kDa bands when blotted with anti-nNOS1–20antibodies, respectively. The 320- and 155-kDa bands represent dimers and monomers of nNOSα; the 250- and 135-kDa bands represent dimers and monomers of nNOSβ. Immunoprecipitation with calmodulin (CaM) showed that a portion of nNOSα dimer was bound with CaM. On the other hand, a portion of nNOSα dimer, nNOSβ dimer, and all monomers lacked CaM binding. The CaM-lacking nNOS fractions reacted with anti-serine 847-phospho-nNOS. In vitro assays of NO production revealed that only the CaM-bound dimeric nNOSα was catalytically active; all other forms were inactive. We suggest that the amount of catalytically active nNOSα dimers may be regulated by serine 847 phosphorylation and equilibrium between dimers and monomers of nNOSα.
Exercise-induced respiratory muscle fatigue: implications for performance
Authors: Romer Lee M. , Polkey Michael I.
Published: December 2007

It is commonly held that the respiratory system has ample capacity relative to the demand for maximal O2and CO2transport in healthy humans exercising near sea level. However, this situation may not apply during heavy-intensity, sustained exercise where exercise may encroach on the capacity of the respiratory system. Nerve stimulation techniques have provided objective evidence that the diaphragm and abdominal muscles are susceptible to fatigue with heavy, sustained exercise. The fatigue appears to be due to elevated levels of respiratory muscle work combined with an increased competition for blood flow with limb locomotor muscles. When respiratory muscles are prefatigued using voluntary respiratory maneuvers, time to exhaustion during subsequent exercise is decreased. Partially unloading the respiratory muscles during heavy exercise using low-density gas mixtures or mechanical ventilation can prevent exercise-induced diaphragm fatigue and increase exercise time to exhaustion. Collectively, these findings suggest that respiratory muscle fatigue may be involved in limiting exercise tolerance or that other factors, including alterations in the sensation of dyspnea or mechanical load, may be important. The major consequence of respiratory muscle fatigue is an increased sympathetic vasoconstrictor outflow to working skeletal muscle through a respiratory muscle metaboreflex, thereby reducing limb blood flow and increasing the severity of exercise-induced locomotor muscle fatigue. An increase in limb locomotor muscle fatigue may play a pivotal role in determining exercise tolerance through a direct effect on muscle force output and a feedback effect on effort perception, causing reduced motor output to the working limb muscles.
The Protective Effect of TiF4, SnF2 and NaF against Erosion-Like Lesions in situ
Authors: Hove L.H. , Holme B. , Young A. , Tveit A.B.
Published: December 2007

The aim of this in situ study was to compare the protective effect of TiF4, SnF2 and NaF on the development of erosion-like lesions in human enamel. Fourteen human molars were each divided into 4 specimens, mounted on acrylic mouth appliances and worn by 7 volunteers for 9 days. In order to mimic a feasible treatment procedure for patients with voluntary or involuntary gastric reflux, the specimens were etched for 2 min twice a day (0.01 M HCl) and fluoride applications were performed every third day (2 min). The controls were treated as the other specimens except for the fluoride applications. Etch depths and surface roughness changes (Rq) were measured by white light interferometry. Compared with the control, TiF4 and SnF2 reduced the etching depth by 100% (p < 0.001) and 91% (p < 0.001), respectively, and both treatments resulted in an observable surface layer. NaF had no significant protective effect (p = 0.46). It can be concluded that although SnF2 provided significant protection for the enamel surfaces, TiF4 showed the best protection against acid attack, while NaF had no significant protective effect in this study.
Indoxyl Sulfate Reduces Superoxide Scavenging Activity in the Kidneys of Normal and Uremic Rats
Authors: Owada Shigeru , Goto Sumie , Bannai Kenji , Hayashi Hideo , Nishijima Fuyuhiko , Niwa Toshimitsu
Published: December 2007

Background/Aim: Indoxyl sulfate (IS) is a uremic toxin that accelerates the progression of chronic renal failure (CRF). This study aimed at determining whether IS impairs antioxidative systems (redox status) in the kidney. Methods: IS was orally administered to normal and subtotally nephrectomized (three fourths and five sixths) rats (CRF rats) for 2 weeks. By use of in vivo and ex vivo electron spin resonance spectroscopy, the kidney redox status was evaluated using carbamoyl-PROXYL as a radical spin probe in living rats, and the kidney superoxide scavenging activity was measured. Immunohistochemistry of superoxide dismutase (SOD) in the kidney was performed. Results: Administration of IS increased serum and kidney levels of IS and serum creatinine and decreased creatinine clearance. CRF rats showed reduced spin reduction rate, prolonged half-life of the spin probe, and reduced superoxide scavenging activity and SOD-positive areas in the kidney as compared with normal rats. Administration of IS further reduced radical spin reduction rate, prolonged half-life of the spin probe, and reduced superoxide scavenging activity and SOD-positive areas in the kidneys. Conclusions: Administration of IS reduced superoxide scavenging activity in the kidneys of normal and CRF rats. Thus, the nephrotoxicity of IS may be induced by impairing the antioxidative systems in the kidney.
SLC40A1 c.1402G→A Results in Aberrant Splicing, Ferroportin Truncation after Glycine 330, and an Autosomal Dominant Hemochromatosis Phenotype
Authors: Lee Pauline L. , Gelbart Terri , West Carol , Barton James C.
Published: December 2007

Background/Aims: To determine the molecular basis of a mild hemochromatosis phenotype in a man of Scottish-Irish descent. Methods: We sequenced genomic DNA to detect mutations of HFE, SLC40A1, TFR2, HAMP, and HFE2. RNA isolated from blood mononuclear cells was used to make cDNA. RT-PCR was performed to amplify ferroportin from cDNA, and amplified products were visualized by electrophoresis and sequenced. Results: The proband was heterozygous for the novel mutation c.1402G→A (predicted G468S) in exon 7 of the ferroportin gene (SLC40A1). Located in the last nucleotide before the splice junction, this mutation results in aberrant splicing to a cryptic upstream splice site located at nt 990 within the same exon. This causes truncation of ferroportin after glycine 330 and the addition of 4 irrelevant amino acids before terminating. The truncated ferroportin protein, missing its C-terminal 241 amino acids, would lack all structural motifs beyond transmembrane region 7. The patient was also heterozygous for the common HFE H63D polymorphism, but did not have coding region mutations in TFR2, HAMP, or HFE2. Conclusions: We conclude that this patient represents a unique example of hemochromatosis due to a single base-pair mutation of SLC40A1 that results in aberrant splicing and truncation of ferroportin.
Laminar Shear Stress Regulates Liver X Receptor in Vascular Endothelial Cells
Authors: Zhu Minjia , Fu Yi , Hou Yingjian , Wang Nanping , Guan Youfei , Tang Chaoshu , Shyy John Y.-J. , Zhu Yi
Published: December 2007

Objective—

The liver X receptors (LXRs) regulate a set of genes involved in lipid metabolism and reverse cholesterol transport. We investigated the mechanism by which shear stress regulates LXR in vascular endothelial cells (ECs).

Methods and Results—

Western blot showed that the protein level of LXRα and its target ABCA1 in the mouse thoracic aorta was higher than that in the aortic arch. As well, the mRNA level of LXR and its target genes ABCA1, ABCG1, ApoE, and LPL in the thoracic aorta was higher. In vitro, bovine aortic ECs were subjected to a steady laminar flow (12 dyne/cm
2
). The expressions of LXR and the LXR-mediated transcription were increased by laminar shear stress. Laminar flow increased LXR-ligand binding and the gene expression of sterol 27-hydroxylase (CYP27), which suggests an increased level of LXR ligand in ECs. This effect was attenuated by LXRα and CYP27 RNAi. The decrease of LXR in the aorta of PPARγ
+/−
mice and that of C57 mice fed with PPARγ antagonist suggest the involvement of PPARγ in the LXR induction by flow.

Conclusion—

Laminar flow increases LXR function via a PPARγ-CYP27 dependent mechanism, which reveals an atheroprotective role for laminar flow exerting on endothelium.
Thyroid Hormone Regulates Developmental Titin Isoform Transitions via the Phosphatidylinositol-3-Kinase/ AKT Pathway
Authors: Krüger Martina , Sachse Christine , Zimmermann Wolfram H. , Eschenhagen Thomas , Klede Stefanie , Linke Wolfgang A.
Published: December 2007

Titins, giant sarcomere proteins with major mechanical/signaling functions, are expressed in 2 main isoform classes in the mammalian heart: N2B (3000 kDa) and N2BA (>3200 kDa). A dramatic isoform switch occurs during cardiac development, from fetal N2BA titin (3700 kDa) expressed before birth to a mix of smaller N2BA/N2B isoforms found postnatally; adult rat hearts almost exclusively have N2B titin. The isoform switch, which can be reversed in chronic human heart failure, alters myocardial distensibility and mechanosignaling. Here we determined factors regulating this switch using, as a model system, primary cardiomyocyte cultures prepared from embryonic rats. In standard culture, the mean N2B percentage initially was 14% and increased by ≈60% within 1 week, resembling the in vivo switching. The titin isoform transition was independent of endothelin-1–induced myocyte hypertrophy and was not altered by pacing, contractile arrest, or cell stretch; however, it was modestly impaired by decreasing substrate rigidity and strongly dependent on serum components. Angiotensin II significantly promoted the transition. The mean N2B proportion in 1-week-old cultures dropped 20% to 25% in hormone-reduced medium, but addition of 3,5,3′-triiodo-
l
-thyronine (T3) nearly restored the proportion to that found in standard culture. This T3 effect was not prevented by bisphenol A, a specific inhibitor of the classic genomic pathway of T3 action. In contrast, the titin switch could be stalled by the phosphatidylinositol 3-kinase inhibitor LY294002, which decreased the proportion of N2B mRNA transcripts within hours and suppressed a rapid T3-induced increase in Akt phosphorylation. Also, angiotensin II, but not endothelin-1 or cell stretch, enhanced Akt phosphorylation. Thus, although matrix stiffness modulates developmental titin isoform transitions, these transitions are mainly regulated through phosphatidylinositol 3-kinase/Akt-dependent signaling triggered particularly by T3 via a rapid action pathway.
Medical Complications in a Comprehensive Stroke Unit and an Early Supported Discharge Service
Authors: Indredavik Bent , Rohweder Gitta , Naalsund Eirik , Lydersen Stian
Published: December 2007

Background and Purpose—

The aims of the study were to examine the frequency and timing of predefined medical complications in unselected acute stroke patients treated in an acute comprehensive stroke unit and an early supported discharge service.

Methods—

Four hundred eighty-nine acute stroke patients were included and followed up with assessments of 16 prespecified complications during the first week. Two hundred forty-four of the patients were randomly allocated to a 3-month follow-up.

Results—

During the first week, 312 of 489 patients (63.8%) experienced 1 or more complications. The most common complications were pain in 117 patients (23.9%), temperature ≥38°C in 116 (23.7%), progressing stroke in 90 (18.4%), urinary tract infection in 78 (16.0%), troponin T elevation without criteria of myocardial infarction in 57 (11.7%), chest infections in 55 (11.2%), nonserious falls in 36 (7.4%), and myocardial infarction in 22 (4.5%), whereas stroke recurrence, seizure, deep venous thrombosis, pulmonary embolism, shoulder pain, serious falls, other infections, and pressure sores were each present in ≤2.5% of patients. During the 3-month follow-up, 201 of 244 patients (82.4%) experienced at least 1 complication, the most common of which was pain, which occurred in 134 patients (53.3%), followed by urinary tract infection in 68 (27.9%) and nonserious falls in 61 (25.0%). The severity of stroke on admission was the most important risk factor for developing complications.

Conclusions—

This is the first study of complications in unselected acute stroke patients treated in a comprehensive stroke unit and early supported discharge service and shows that pain, progressing stroke, infections, myocardial infarction, and falls are common complications, whereas others occur infrequently. Most complications occur during the first 4 days, and stroke severity is the most important risk factor.
Role of Promoter Polymorphisms in the Plasma Glutathione Peroxidase (
GPx-3
) Gene as a Risk Factor for Cerebral Venous Thrombosis
Authors: Voetsch Barbara , Jin Richard C. , Bierl Charlene , Deus-Silva Leonardo , Camargo Erica C.S. , Annichino-Bizacchi Joyce M. , Handy Diane E. , Loscalzo Joseph
Published: December 2007

Background and Purpose—

Plasma glutathione peroxidase (GPx-3) is a major antioxidant enzyme in plasma and the extracellular space that scavenges reactive oxygen species produced during normal metabolism or after oxidative insult. A deficiency of this enzyme increases extracellular oxidant stress, promotes platelet activation, and may promote oxidative posttranslational modification of fibrinogen. We recently identified a haplotype (H
2
) in the
GPx-3
gene promoter that increases the risk of arterial ischemic stroke among children and young adults.

Methods—

The aim of this study is to identify possible relationships between promoter haplotypes in the
GPx-3
gene and cerebral venous thrombosis (CVT). We studied the
GPx-3
gene promoter from 23 patients with CVT and 123 young controls (18 to 45 years) by single-stranded conformational polymorphism and sequencing analysis.

Results—

Over half of CVT patients (52.1%) were heterozygous (H
1
H
2
) or homozygous (H
2
H
2
) carriers of the H
2
haplotype compared with 12.2% of controls, yielding a more than 10-fold independent increase in the risk of CVT (OR=10.7; 95% CI, 2.70 to 42.36;
P
<0.0001). Among women, the interaction of the H
2
haplotype with hormonal risk factors increased the OR of CVT to almost 70 (
P
<0.0001).

Conclusions—

These findings show that a novel GPx-3 promoter haplotype is a strong, independent risk factor for CVT. As we have previously shown that this haplotype is associated with a reduction in transcriptional activity, which compromises antioxidant activity and antithrombotic benefits of the enzyme, these results suggest that a deficiency of
GPx-3
leads to a cerebral venous thrombophilic state.
Comparison of Intraarterial and Intravenous Thrombolysis for Ischemic Stroke With Hyperdense Middle Cerebral Artery Sign
Authors: Mattle Heinrich P. , Arnold Marcel , Georgiadis Dimitrios , Baumann Christian , Nedeltchev Krassen , Benninger David , Remonda Luca , von Büdingen Christian , Diana Anca , Pangalu Athina , Schroth Gerhard , Baumgartner Ralf W.
Published: December 2007

Background and Purpose—

It is unclear whether intraarterial (IAT) or intravenous (IVT) thrombolysis is more effective for ischemic stroke with hyperdense middle cerebral artery sign (HMCAS) on computed tomography (CT). The aim of this study was to compare IAT and IVT in stroke patients with HMCAS.

Methods—

Comparison of data from 2 stroke units with similar management of stroke associated with HMCAS, except that 1 unit performed IAT with urokinase and the other IVT with plasminogen activator. Time to treatment was up to 6 hours for IAT and up to 3 hours for IVT. Outcome was measured by mortality and the modified Rankin Scale (mRS), dichotomized at 3 months into favorable (mRS 0 to 2) and unfavorable (mRS 3 to 6).

Results—

One hundred twelve patients exhibited a HMCAS, 55 of 268 patients treated with IAT and 57 of 249 patients who underwent IVT. Stroke severity at baseline and patient age were similar in both groups. Mean time to treatment was longer in the IAT group (244±63 minutes) than in the IVT group (156±21 minutes;
P
=0.0001). However, favorable outcome was more frequent after IAT (n=29, 53%) than after IVT (n=13, 23%;
P
=0.001), and mortality was lower after IAT (n=4, 7%) than after IVT (n=13, 23%;
P
=0.022). After multiple regression analysis IAT was associated with a more favorable outcome than IVT (
P
=0.003) but similar mortality (
P
=0.192).

Conclusion—

In this observational study intraarterial thrombolysis was more beneficial than IVT in the specific group of stroke patients presenting with HMCAS on CT, even though IAT was started later. Our results indicate that a randomized trial comparing both thrombolytic treatments in patients with middle cerebral artery occlusion is warranted.
Association of Adiponectin With Cerebrovascular Disease
Authors: Matsumoto Masatoshi , Ishikawa Shizukiyo , Kajii Eiji
Published: December 2007

Background and Purpose—

Even though adiponectin is associated with many traditional cardiovascular risk factors, studies assessing the association between adiponectin and cerebrovascular disease (CVD) are scarce. We assessed the odds of CVD at different plasma levels of adiponectin.

Methods—

A nested case–control study was conducted involving 5243 subjects, drawn from 12 490 subjects of the Jichi Medical School Cohort Study, whose blood samples had been drawn between 1992 and 1995. Over an average of 9.7 years of follow-up, through 2005, 179 patients with cerebrovascular events were identified, in addition to 630 controls matched for age, sex, and community (total n=809). Odds ratios were estimated relative to the highest quartile of adiponectin level.

Results—

There was neither a significant difference in the odds of stroke between the lowest and highest adiponectin quartiles, nor a significant linear trend toward a reduced risk of stroke at higher adiponectin levels. These results did not change after excluding participants with diabetes, impaired glucose metabolism, or metabolic syndrome. The odds of ischemic stroke in the lowest quartile were significantly higher than in the highest quartile, when adjusted for age and sex (OR 2.04 [95% CI, 1.09 to 3.80]). However, the odds failed to achieve statistical significance when adjusted further for other cardiovascular risk factors. Again exclusion of subjects with diabetes, impaired glucose metabolism, or metabolic syndrome did not alter results.

Conclusions—

Adiponectin levels are not independently associated with stroke or brain infarction. The use of adiponectin as a cerebrovascular disease predictor may be premature.
Positive Antecedent and Consequent Components in Child Compliance Training
Authors: Speights Roberts Dannell , Tingstrom Daniel H. , Olmi D. Joe , Bellipanni Kimberly D.
Published: December 2007

This study evaluates the effects of positive antecedent (effective instruction delivery and time-in) and consequent components (contingent praise) on the compliance of 4 children in a clinic setting. Results suggest that the use of effective instruction delivery alone increased compliance above baseline levels for the 4 children and that the additions of time-in and contingent praise further increased compliance for 3 of the 4 children. All three positive treatment components resulted in compliance greater than 80% for all children. Compliance levels were maintained at 1-month follow-up for 2 children. Results are discussed in terms of the benefits to using all of the positive components in compliance training.