bluuebunny/crossref_metadata_2025_split huggingface dataset:
Palynostratigraphy of the Upper Carboniferous Langesttian-Duckmantian Stage Boundary in Britain
Authors: Mclean Duncan , Owens Bernard , Bodman David 
Published: September 2007

Abstract

A critique of palynostratigraphic zonation schemes associated with the Langsettian-Duckmantian Stage boundary shows that, at high levels of stratigraphic resolution, most criteria used as palynological proxies for the position of the boundary are unsuitable. Most importantly, in the Duckmantian stratotype section the highest stratigraphic occurrence of the index species
Schulzospora rara
is above (rather than below or within) the Vanderbeckei Marine Band, the base of which defines the Duckmantian Stage. A cored section through the boundary in southern North Sea well 44/22-1 displays comparable microfloral distributions. While data are as yet too sparse to provide detailed answers, the findings have implications for understanding how marine flooding events affected Carboniferous microfloral evolution and extinction. Ultimately this influences how microfloral biozone boundaries relate to the regional European Upper Carboniferous stage boundaries, which are largely defined in relation to strata deposited during marine flooding events similar to that associated with the Langsettian-Duckmantian boundary. The miospore genus
Sinuspores
Artüz is emended, and two new taxa are described:
Gondisporites bulboides
sp. nov. and
Hymenospora murdochensis
sp. nov.
Response of tropical African and East Atlantic climates to orbital forcing over the last 1.7 Ma
Authors: Jahn B. , Schneider R. R. , Müller P.-J. , Donner B. , Röhl U. 
Published: September 2007

Abstract
Records of organic matter accumulation, organic carbon isotopic composition and iron content covering the last 1.7 Ma are presented for the Congo Fan Ocean Drilling Program (ODP) Site 1075, and are compared with their counterparts from ODP Site 663 in the equatorial upwelling region. They are discussed with regard to variations in African precipitation and Congo River discharge and in the context of changes in trade-wind-driven marine productivity for the tropical Atlantic at periodicities typical of Milankovitch forcing. On the Congo Fan, elevated total organic carbon mass accumulation rates (TOC MAR) and Fe intensities occur predominantly during interglacial periods when the African monsoon was most intense. Band-pass filtering applied to TOC MAR shows distinct precessional variations, indicating that the African climate was largely controlled by low-latitude insolation changes. Only for the last 0.6 Ma, an interval of enhanced glacial-interglacial climate changes, is the precessional TOC MAR signal superimposed by a strong 100 ka oscillation. In contrast, variations in terrestrial iron input to the Congo Fan indicate pronounced 100 ka variance already well before global glacial-interglacial cycles increased in amplitude between 0.9 and 0.6 Ma. Obliquity cycles in the Fe signal are strongly expressed for the last 0.9 Ma. The highest amplitudes in the precessional variance of fluvial Fe input occur when amplitudes in the 100 ka oscillation were at intermediate levels and reveal a 800 ka cycle in phase shift with respect to precessional forcing. Together with a pronounced 800 ka signal in the 100 ka amplitude variations during the last 1.7 Ma, the Congo Fan iron record therefore suggests that eccentricity modulation of the low-latitude insolation directly influenced the equatorial African monsoon system and probably the weathering conditions on land. It further suggests that low-latitude precessional forcing and monsoonal response in the tropics might have played an important role for 100 ka cycles in global climate well before huge continental ice sheets existed.
Deep-sea benthic foraminiferal record of the mid-Pleistocene transition in the SW Pacific
Authors: Hayward Bruce W. , Grenfell Hugh R. , Sabaa Ashwaq T. , Sikes Elizabeth 
Published: September 2007

Abstract
Benthic foraminiferal faunas from three bathyal sequences provide a proxy record of oceanographic changes through the mid-Pleistocene transition (MPT) on either side of the Subtropical Front (STF), east of New Zealand. Canonical correspondence analyses show that factors related to water depth, latitude and climate cycles were more significant than oceanographic factors in determining changes in faunal assemblage composition over the last 1 Ma. Even so, mid-Pleistocene faunal changes are recognizable and can be linked to inferred palaeoceanographic causes.
North of the largely stationary STF the faunas were less variable than to the south, perhaps reflecting the less extreme glacial-interglacial fluctuations in the overlying Subtropical Surface Water. Prior to Marine Isotope Stage (MIS) 21 and after MIS 15, the northern faunas had fairly constant composition, but during most of the MPT faunal composition fluctuated in response to climate-related food-supply variations. Faunal changes through the MPT suggest increasing food supply and decreasing dissolved bottom oxygen.

South of the STF, beneath Subantarctic Surface Water, mid-Pleistocene faunas exhibited strong glacial-interglacial fluctuations, inferred to be due to higher interglacial nutrient supply and lower oxygen levels. The most dramatic faunal change in the south occurred at the end of the MPT (MIS 15–12), with an acme of
Abditodentrix pseudothalmanni
, possibly reflecting higher carbon flux and lowered bottom oxygen.

This study suggests that the mid-Pleistocene decline and extinction of a group of elongate, cylindrical deep-sea foraminifera may have been related to decreased bottom oxygen concentrations as a result of slower deep-water currents.
Distribution of the calcareous nannofossil
Reticulofenestra asanoi
within the Early-Middle Pleistocene transition in the Mediterranean Sea and Atlantic Ocean: correlation with magneto- and oxygen isotope stratigraphy
Authors: Reale Viviana , Monechi Simonetta 
Published: September 2007

Abstract

Quantitative analyses of the calcareous nannofossil
Reticulofenestra asanoi
and related species have been performed on the Early-Middle Pleistocene transition in the Mediterranean Sea (ODP Sites 976 and 963) and Atlantic Ocean (DSDP Hole 610A) in order to improve the understanding of their stratigraphic distributions. Abundance patterns have allowed the identification of the lowest common occurrence (LCO) and highest common occurrence (HCO) of
R. asanoi
in a short interval below and above the lowest occurrence of
Gephyrocapsa
sp. 3. Correlation with oxygen isotope stratigraphy at Site 976 places the LCO of
R. asanoi
at the Marine Isotope Stage (MIS) 34-33 transition and its HCO at the MIS 23-22 transition. At Site 963, the HCO of
R. asanoi
(estimated age of 0.96 Ma correlated to MIS 25) is regarded as ‘artificially’ low, and its highest occurrence (estimated age 0.90 Ma correlated to MIS 23) has therefore been used for bio-chronostratigraphic correlation. The LCO of
R. asanoi
is estimated at 1.05 Ma at Site 963 and 1.17 Ma at Hole 610A, which suggests correlation to MIS 30 and MIS 35, respectively. These data suggest a possible diachrony for the LCO of
R. asanoi
.
Pollen records and climatic cycles in the North Mediterranean region since 2.7 Ma
Authors: Suc Jean-Pierre , Popescu Speranta-Maria 
Published: September 2007

Abstract

This synthesis incorporates the 16 most important pollen records available across the North Mediterranean region
sensu lato
for the last 2.7 Ma. Their location is discussed with respect to the present-day bioclimatic Mediterranean realm. A special effort has been made to redraw, where necessary, the pollen records in terms of modern cyclostratigraphy. The complexity of the evolution of the Mediterranean flora and vegetation as forced by the climatic cycles is evident. The influence of the latitudinal thermic (and xeric) gradient is confirmed, and the superimposition of a longitudinal gradient, forced by the Asian monsoon, is considered. The Mediterranean flora and vegetation were not altered by any important event during the Early-Middle Pleistocene transition between 1.2 and 0.7 Ma.
Climatic patterns revealed by pollen and oxygen isotope records across the Matuyama-Brunhes Boundary in the central Mediterranean (southern Italy)
Authors: Capraro L. , Asioli A. , Backman J. , Bertoldi R. , Channell J. E. T. , Massari F. , Rio D. 
Published: September 2007

Abstract

A
c.
50 m thick section located in the Crotone Basin (southern Italy) was investigated using oxygen isotopes, pollen and planktonic foraminifera. The section records two complete transgressive-regressive cycles mainly driven by glacio-eustasy. Biostratigraphy and oxygen isotope chronology indicate that the section spans from Marine Isotope Stage (MIS) 22 (
c.
0.87 Ma) to MIS 18.3 (
c.
0.73 Ma), thus straddling the Matuyama-Brunhes (M-B) boundary which occurs in the middle of MIS 19. The rich pollen assemblages provide a unique record of the vegetation in the central Mediterranean during the Early-Middle Pleistocene climatic transition. Interglacials are characterized by a mesothermic vegetation similar to the present day, whereas a rain-demanding conifer forest dominates the glacials of MIS 20 and MIS 18. This is unexpected because it is generally considered that during the Pleistocene, glacials in central Mediterranean were characterized by steppe (arid) conditions. By contrast, arid conditions occur during the deglaciations. These results are inconsistent with the widespread practice of linking glacials with arid conditions in the central Mediterranean during Pliocene and Early Pleistocene times. This study emphasizes the need to establish more accurate land-sea correlation.
Early-Middle Pleistocene structural changes in mammalian communities from the Italian peninsula
Authors: Palombo Maria R. , Raia Pasquale , Giovinazzo Caterina 
Published: September 2007

Abstract
The late Early and Middle Pleistocene mammal fossil record of Italy has been revised by grouping faunal lists into discrete faunal complexes, termed cluster units, by means of bootstrapped cluster analysis which allows the evaluation of group partition sharpness. These complexes have been compared with previously erected Italian biochrons and then analysed for their body size (by cenogram analysis) and diversity trends. Some considerations about changes in predator-prey ratios are made. It is shown that diversity increased sharply at the onset of the middle Galerian mammal age, coincident with the well-known shift from 40 to 100 ka glacial-interglacial periodicity. This increased diversity was entirely driven by the concurrent arrival in Italy of some large ungulates. Cenograms reveal that the climate became wetter and markedly cooler following the arid conditions that characterize the late Early Pleistocene. Wetter environments are generally expected to sustain a higher proportion of large herbivore species. Because carnivore species did not respond in the same way, the predator-prey ratio changed in favour of prey. In summary, the transition from Early to Middle Pleistocene faunas (from early to middle Galerian mammal ages) represents a major reorganization in the large-mammal complexes from the Italian peninsula. This was reflected in both the diversity and trophic structure of large-mammal communities.
Hominins and the Early-Middle Pleistocene transition: evolution, culture and climate in Africa and Europe
Authors: McNabb John 
Published: September 2007

Abstract
Some of the more important evidence is reviewed for the archaeology of hominin colonization associated with the Early-Middle Pleistocene transition. This is done by reference to the nature of migration ‘out of Africa’ before the interval of transition, across the transition itself, and then after it. Technologically assisted behaviour may not have been so important in the colonization process, behaviour and biology being the primary factors that led to the success of a migrating species. While climate change and especially shifts in local aridity would have been experienced and possibly remembered by localized hominin groups, the Acheulean behavioural repertoire did not change much across Africa and Europe over a million years of time. It merely adapted to local conditions. The Acheulean was a generalized hand-held processing technology for a generalized hominin.
The Role of Chloride in Al Oxide Surface Transformations and Pitting -an AFM Study
Authors: Vasiljevic Natasa , Copeland Robert G. G. , Missert N. A. 
Published: September 2007

In this study we used the in situ AFM technique to examine the Al surface morphological transformations during anodic polarization. In order to elucidate the possible role of chloride in the surface oxide breakdown process, we conducted in situ AFM polarization studies in sulfate (50 mM K2SO4) and chloride (50 mM NaCl) solutions where Al corrosion behavior is known to be different.	The results show different changes and structures in two electrolytes: (a) for the case of polarization in sulfate solutions, uniform changes of oxide morphology are observed most likely resulting from oxide hydration and growth; (b) for the case of polarization in chloride solutions, morphological changes are observed to be surface-site energy dependant.	The changes of Al-oxide are very pronounced around the regions of faceted edges and grain boundaries i.e. regions of higher local roughness and curvature.
Anion Radical of 3,5-bis(1,1-dimethylethyl)-4-oxo-2,5-Cyclohexadienylideneacetonitrile: Dimerization
Authors: ul Haque Inam , Khan Asim , Sadaf Shamaila 
Published: September 2007

3,5-Bis(1,1-dimethylethyl)-4-oxo-2,5- cyclohexadienylideneacetonitrile, QM, is an electron acceptor. Simulation of cyclic voltammogram of 3,5-Bis(1,1-	dimethylethyl)-4-oxo-2,5-cyclohexadienylideneacetonitrile, QM,	in acetonitrile at platinum electrode was carried out, and a	scheme was suggested to obtain the heterogeneous rate	constants for electron transfer. The results of simulations based on two shareware programs are generally consistent with theoretical and experimental work.
Sexual Dimorphism in the Electrocardiographic Dynamics of Human Ventricular Repolarization
Authors: Lehmann Michael H. , Yang Hua 
Published: September 2007

Background—Previous characterizations of sex differences in ST-T waveform voltages have largely focused on amplitudes at selected time points during repolarization, subject to potential distortions from variations in heart rate (HR) or reliance on a JT-normalized time scale.Methods and Results—Using digitized 12-lead ECGs from 553 normal adults (426 males) with HRs confined to 60±1, 70±1, or 80±1 bpm, we derived X, Y, and Z lead voltages and then generated, for each HR category by sex, summary (population mean) resultant spatial vector amplitudes (ST-TXYZ) and instantaneous slopes (dV/dtXYZ) at successive 4-ms intervals following the J point. Within each HR category, there was an early intersex divergence of ST-TXYZtrajectories (95% CIs nonoverlapping), with men exhibiting 2- to 3-fold greater dV/dtXYZvalues during the ST segment and achieving greater maximum TXYZand dV/dtXYZvalues than women; descending TXYZlimbs were relatively more concordant between sexes but still steeper in men. The early sex differences in repolarization dynamics persisted in multiple regression analyses that took into account age and a morphometric index of left ventricular mass. In men, absolute values of extrema of TXYZand dV/dtXYZvaried inversely with HR.Conclusions—At physiological resting HRs, the spatial ST-T vector voltage time trajectory is steeper in men than in women, beginning virtually from the J point. In addition to its mechanistic implications, the demonstration of marked sensitivity of ST-TXYZand especially dV/dtXYZto sex raises the possibility that these time-based, ECG-derived parameters might be informative in pathophysiological studies of ventricular repolarization.
Gating-Dependent Mechanisms for Flecainide Action inSCN5A-Linked Arrhythmia Syndromes
Authors: Viswanathan Prakash C. , Bezzina Connie R. , George Alfred L. , Roden Dan M. , Wilde Arthur A.M. , Balser Jeffrey R. 
Published: September 2007

Background—Mutations in the cardiac sodium (Na) channel gene (SCN5A) give rise to the congenital long-QT syndrome (LQT3) and the Brugada syndrome. Na channel blockade by antiarrhythmic drugs improves the QT interval prolongation in LQT3 but worsens the Brugada syndrome ST-segment elevation. Although Na channel blockade has been proposed as a treatment for LQT3, flecainide also evokes “Brugada-like” ST-segment elevation in LQT3 patients. Here, we examine how Na channel inactivation gating defects in LQT3 and Brugada syndrome elicit proarrhythmic sensitivity to flecainide.Methods and Results—We measured whole-cell Na current (INa) from tsA-201 cells transfected with ΔKPQ, a LQT3 mutation, and 1795insD, a mutation that provokes both the LQT3 and Brugada syndromes. The 1795insD and ΔKPQ channels both exhibited modified inactivation gating (from the closed state), thus potentiating tonicINablock. Flecainide (1 μmol/L) tonic block was only 16.8±3.0% for wild type but was 58.0±6.0% for 1795insD (P<0.01) and 39.4±8.0% (P<0.05) for ΔKPQ. In addition, the 1795insD mutation delayed recovery from inactivation by enhancing intermediate inactivation, with a 4-fold delay in recovery from use-dependent flecainide block.Conclusions—We have linked 2 inactivation gating defects (“closed-state” fast inactivation and intermediate inactivation) to flecainide sensitivity in patients carrying LQT3 and Brugada syndrome mutations. These results provide a mechanistic rationale for predicting proarrhythmic sensitivity to flecainide based on the identification of specificSCN5Ainactivation gating defects.
Significance of Chymase-Dependent Angiotensin II–Forming Pathway in the Development of Vascular Proliferation
Authors: Nishimoto Masayoshi , Takai Shinji , Kim Shokei , Jin Denan , Yuda Atsushi , Sakaguchi Masato , Yamada Mayumi , Sawada Yoshihide , Kondo Keiichiro , Asada Kunio , Iwao Hiroshi , Sasaki Shinjiro , Miyazaki Mizuo 
Published: September 2007

BackgroundVascular tissues of humans and dogs contain chymase as an angiotensin II–forming enzyme. In this study, we investigated whether chymase-dependent angiotensin II formation plays a crucial role in the development of vascular proliferation in dog grafted veins.Methods and ResultsThe right external jugular vein of dogs was grafted to the ipsilateral carotid artery. As a control group, the right external jugular veins in dogs that had not received grafts were used. In the chymase inhibitor–treated group, the vein was infiltrated with 10 μmol/L Suc-Val-Pro-PheP(OPh)2and was grafted to the carotid artery. In the placebo-treated group, ACE activity in the grafted veins was significantly lower than that in the control veins up to 7 days after the operation, whereas chymase activity was increased significantly. After 7 days, the mRNA levels of collagen I, collagen III, and fibronectin, all of which are induced by an increase of angiotensin II action, were significantly increased in the grafted veins, and the intima-media ratio of the grafted veins was also increased. In the chymase inhibitor–treated group, the chymase activity in the grafted veins 7 days after the operation was suppressed to 12.1%. The elevated mRNA levels of fibronectin, collagen I, and collagen III in the grafted veins were significantly suppressed by treatment with the chymase inhibitor, and the intima-media ratio was also decreased significantly.ConclusionsWe demonstrate for the first time that chymase-dependent angiotensin II formation plays an important role in the development of vascular proliferation in the grafted veins.
Angiotensin II Induces Circadian Gene Expression of Clock Genes in Cultured Vascular Smooth Muscle Cells
Authors: Nonaka Hidemi , Emoto Noriaki , Ikeda Koji , Fukuya Hiroyuki , Rohman Mohammad Saifur , Raharjo Sunu Budhi , Yagita Kazuhiro , Okamura Hitoshi , Yokoyama Mitsuhiro 
Published: September 2007

BackgroundDaily rhythms of mammalian physiology and endocrinology are regulated by circadian pacemakers. The master circadian pacemaker resides in the suprachiasmatic nucleus, which is located in the hypothalamus of the brain, but circadian oscillators also exist in peripheral tissues. Because many studies have demonstrated apparent circadian variations in the frequency of cardiovascular disorders, it is of great interest to investigate a possible relation between circadian gene expression and cardiovascular function. We examined whether a circadian oscillation system exists in the aorta and/or in cultured vascular smooth muscle cells (VSMCs).Methods and ResultsThe mRNA levels of clock genes were assayed by northern blot analysis. The mouse aorta showed a clear circadian oscillation in the expression ofmPer2,dbp, andBmal1. Brief treatment of VSMCs with angiotensin II induced a robust increase inmPer2gene expression, followed by a marked reduction inmPer2mRNA levels and subsequent synchronous cycling ofmPer2,dbp, andBmal1mRNAs. The induction ofmPer2in VSMCs by angiotensin II was completely abolished by treatment with CV11947, a specific angiotensin II type1 receptor antagonist.ConclusionsThe present results demonstrate that the aorta and VSMCs possess a circadian oscillation system which is comparable to that of the suprachiasmatic nucleus and that the circadian gene expression in VSMCs is induced by angiotensin II through the angiotensin II type1 receptor. Our in vitro system will provide a useful tool to further analyze the physiological significance of the peripheral clock in cardiovascular function.
Electrophysiological Effects of Ibutilide in Patients With Accessory Pathways
Authors: Glatter Kathryn A. , Dorostkar Parvin C. , Yang Yanfei , Lee Randall J. , Van Hare George F. , Keung Edmund , Modin Gunnard , Scheinman Melvin M. 
Published: September 2007

BackgroundAtrial fibrillation (AF) may cause life-threatening ventricular arrhythmias in patients with Wolff-Parkinson-White syndrome. We prospectively evaluated the effects of ibutilide on the conduction system in patients with accessory pathways (AP).Methods and ResultsIn part I, we gave ibutilide to 22 patients (18 men, 31±13 years of age) who had AF during electrophysiology study, including 6 pediatric patients ≤18 years of age. Ibutilide terminated AF in 21 of 22 patients (95%) during or 8±5 minutes after infusion and prolonged the shortest preexcited R-R interval during AF. Successful ablation was performed in all patients. In part II, ibutilide was given to 18 patients (14 men, 28±21 years) to assess its effects on the AP and conduction system. Ibutilide prolonged the antegrade atrioventricular node effective refractory period (ERP) (from 252±60 to 303±70 ms;P<0.02). Ibutilide caused transient loss of the delta wave in 1 patient and abolished inducible tachycardia in 2 patients, although retrograde mapping still allowed for successful AP ablation. The antegrade AP ERP prolonged from 275±40 to 320±60 ms (P<0.01), as did the antegrade AP block cycle length; the retrograde AP ERP and block cycle length similarly prolonged with ibutilide. The relative and effective refractory period of the His-Purkinje system increased in 61% of patients after ibutilide. There were no adverse side effects.ConclusionsWe report the use of ibutilide in terminating AP-mediated AF, including the first report in the pediatric population. Ibutilide prolonged refractoriness of the atrioventricular node, His-Purkinje system, and AP.