bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the difficulty of assigning crustal residence, magmatic protolith and metamorphic ages to Lewisian granulites: constraints from combined
in situ
U–Pb and Lu–Hf isotopes
Authors: Whitehouse M. J. , Kemp A. I. S. 
Published: June 2010

Abstract

Zircons from two granulite facies gneisses from the central region of the Lewisian Complex have been investigated by high spatial resolution ion-microprobe U–Pb dating and laser ablation combined Pb–Hf isotope methods. The ion-microprobe data reveal a complex pattern of zircon ages distributed along the concordia curve between the time of granulite facies metamorphism at
c
. 2.5 Ga and the oldest zircon in each sample (respectively 2.89 Ga and 3.04 Ga). This Pb-loss pattern complicates assignment of an unambiguous magmatic protolith age to the zircon although cathodoluminescence (CL) imaging is used to suggest a preferred age of
c
. 2.85 Ga for both samples, with older grains being inherited.
In situ
Hf isotopes show a larger spread in the sample containing older grains which is also consistent with inheritance and further suggests that several crust extraction events are represented in the inherited population. Comparison of Hf isotope compositions with plausible model evolution curves suggests that crustal precursors to the Lewisian granulites were derived from their mantle source at
c
. 3.05–3.2 Ga.

Supplementary material:

Analytical methods and data tables are available at:
http://www.geolsoc.org.uk/SUP18395
The Laxford Shear Zone: an end-Archaean terrane boundary?
Authors: Goodenough K. M. , Park R. G. , Krabbendam M. , Myers J. S. , Wheeler J. , Loughlin S. C. , Crowley Q. G. , Friend C. R. L. , Beach A. , Kinny P. D. , Graham R. H. 
Published: June 2010

Abstract
The Lewisian Gneiss Complex of northwestern Scotland consists of Archaean gneisses, variably reworked during the Proterozoic. It can be divided into three districts – a central granulite-facies district between districts of amphibolite-facies gneiss to the north and south. Recent work has interpreted these districts in terms of separate terranes, initiating a controversy that has implications for how Precambrian rocks are understood worldwide. The northern district of the Lewisian Gneiss Complex (the Rhiconich terrane) is separated from the central district (the Assynt terrane) by a broad ductile shear zone known as the Laxford Shear Zone. This paper reviews the geology of the Laxford Shear Zone, clarifying field relationships and discussing other evidence, to consider whether or not it does indeed represent a terrane boundary. A detailed review of field, geochemical and geochronological evidence supports the recognition of the separate Assynt and Rhiconich terranes. Mafic dykes (the Scourie Dyke Swarm) and granitoids, of Palaeoproterozoic age, occur on both sides of the Laxford Shear Zone and thus the terranes were most probably juxtaposed during the late Archaean to early Palaeoproterozoic Inverian event. Subsequently, the less-competent, more-hydrous amphibolite-facies gneisses of the Rhiconich terrane were affected by later Palaeoproterozoic (Laxfordian) deformation and partial melting, to a greater extent than the more-competent granulite-facies gneisses of the Assynt terrane.
The North‐West Highlands memoir: a century-old legacy for understanding Earth before Pangaea
Authors: Dalziel Ian W. D. 
Published: June 2010

Abstract
Benjamin Peach, John Horne and their co-workers recognized a century ago that the identical fauna and lithofacies of the lower Palaeozoic strata in the NW Highlands of Scotland and the North American craton could only be explained if they were: ‘part of one and the same geological and zoological province’. In this sense their work provided critical geological underpinning for the subsequent understanding of Mesozoic–Cenozoic seafloor spreading and continental drift. ‘Tectonic tracers’ such as the fragment of Laurentian craton in the NW Highlands of Scotland, provide the strongest evidence available for deciphering pre-Pangaea palaeogeography. The Laurentian craton appears to have left several such tectonic ‘calling cards’ in today's southern continents. Intriguingly, it is the presence in the Andean Precordillera of northwestern Argentina of an early Palaeozoic fauna identical to that of the NW Highlands that provides perhaps the most unequivocal geological clue to pre-Pangaea palaeogeography. Recent work in East Antarctic and Laurentian cratons has provided a positive test of the hypothesis that they were once juxtaposed prior to the Neoproterozoic opening of the Pacific Ocean basin. Geochronology and isotope geochemistry, supported by palaeomagnetic studies indicate that the Coats Land crustal block of East Antarctica at the head of the Weddell Sea is also a fragment of the Laurentian craton. These three ‘tectonic tracers’ permit tracking of the Laurentian craton in relation to the present southern continents from the Neoproterozoic break-up of the Rodinian supercontinent to the late Palaeozoic assembly of Pangaea.
Calcareous tufa as indicators of climatic variability: a case study from southern Tuscany (Italy)
Authors: Capezzuoli Enrico , Gandin Anna , Sandrelli Fabio 
Published: June 2010

Abstract
A carbonate terraced succession mainly consisting of fluvial/palustrine calcareous tufa and of lacustrine limestone was deposited during recent Quaternary in a limited segment of the Valdelsa fluvial pattern (southern Tuscany, Italy).
The radiometric data obtained from three carbonate terraces indicate that the depositional/erosional history of the Valdelsa succession during Late Pleistocene–Holocene, has been constrained by the same cyclic events observed in coeval detrital lacustrine successions of Central Italy. At least three of the Valdelsa carbonate Synthems and the interposed erosional phases can be correlated with the major climatic changes recognized in the European–Mediterranean area, from the Last Glacial Interstadial through the Younger Dryas to the Atlantic ‘Optimum Climatic’, the Sub-Boreal and finally at 2.5 ka the last Sub-Atlantic oscillation.
This climatic correlation and the radiometric data imply that the deposition of calcareous tufa in Valdelsa was mainly dependent on rainfall availability and, consequently, was active during the milder oscillations within the cold periods.
Calcium carbonate precipitation by cyanobacterial polysaccharides
Authors: Dittrich M. , Sibler S. 
Published: June 2010

Abstract

Cyanobacteria have been recognized as key players in the precipitation of calcium carbonate in marine and freshwater systems. These bacteria increase pH, (as a result of photosynthetic activity) and also produce extracellular polysaccharides, which act as binding sites for Ca
2+
and CO
3
2−
. Both processes influence the morphology and the mineralogy of the carbonate minerals. In order to clarify the role of polysaccharides of picocyanobacteria upon calcium carbonate precipitation, both their buffering capacity and ability to induce precipitation need to be investigated. In this experimental study, we characterized the polysaccharides of three unicellular autotrophic picocyanobacterial
Synechococcus
-type strains by potentiometric titration and infrared spectroscopy. Potentiometric titrations were conducted to determine the total buffering capacity. The nature and concentration of active sites of the polysaccharides was clarified with the aid of potentiometric titration and spectral analysis of an aqueous cellular suspension. Precipitation experiments with polysaccharides of different strains allowed an estimation of their potential to precipitate calcium carbonate. The results presented here indicate that polysaccharides from cyanobacteria have a strong potential to exchange protons with their surrounding environment. Precipitation experiments demonstrated that extracellular polysaccharides of all the strains studied able to precipitate calcium carbonate.
Microbial influence on macroenvironment chemical conditions in alkaline (tufa) streams: perspectives from
in vitro
experiments
Authors: Rogerson M. , Pedley H. M. , Middleton R. 
Published: June 2010

Abstract

Tufas represent a palaeoclimatic archive of potentially global significance. However, uncertainty remains over the exact process of calcite precipitation from these systems, inhibiting our ability to decipher the precise meaning of geochemical records. For example, field studies of alkaline stream systems are unable to disentangle the influence of temperature and photosynthesis on ambient hydrochemistry on diurnal and annual timescales. This report describes a series of flume experiments in which temperature and light conditions are manipulated separately. These experiments reveal that precipitation of calcite occurs preferentially under conditions of rising pH, and consequently at the night–day transition. The amplitude of diurnal changes is regulated by the buffering capacity (i.e. alkalinity) of the ambient water and by the daytime balance of photosynthesis and respiration. Respiration is shown to be strongly affected by temperature, whereas photosynthesis is found to be limited by nutrient and/or DIC availability making temperature impacts minor. Consequently, macroenvironment pH during both day and night-time tend to be higher under lower temperatures, in contrast to expectation. These observations may have potential implications for the isotopic geochemistry of tufa carbonate, promoting slightly lower δ
18
O, due to the carbonate ion effect, and more significantly negative δ
13
C, due to incorporation of respired CO
2
accumulated during the night. The observation that long periods of daylight are not necessarily needed for photosynthetically induced precipitation to occur confirm previous arguments that seasonal lamination requires either strong variability in ambient physicochemical activity or an ecological change in the microbial assemblage, and cannot be ascribed to reduced temperature and light intensity.
Tufa-forming biofilms of German karstwater streams: microorganisms, exopolymers, hydrochemistry and calcification
Authors: Arp Gernot , Bissett Andrew , Brinkmann Nicole , Cousin Sylvie , De Beer Dirk , Friedl Thomas , Mohr Kathrin I. , Neu Thomas R. , Reimer Andreas , Shiraishi Fumito , Stackebrandt Erko , Zippel Barbara 
Published: June 2010

Abstract

To understand mechanisms of tufa biofilm calcification, selected karstwater stream stromatolites in Germany have been investigated with regard to their hydrochemistry, biofilm community, exopolymers, physicochemical microgradients, calcification pattern and lamination. In stream waters, CO
2
degassing drives the increase in calcite saturation to maximum values of approximately 10-fold, independent from the initial Ca
2+
/alkalinity ratio. For the cyanobacteria of tufa biofilms, a culture-independent molecular approach showed that microscopy of resin-embedded biofilm thin sections underestimated the actual diversity of cyanobacteria, i.e. the six cyanobacteria morphotypes were opposed to nine different lineages of the 16S rDNA phylogeny. The same morphotype may even represent two genetically distant cyanobacteria and the closest relatives of tufa biofilm cyanobacteria may be from quite different habitats. Diatom diversity was even higher in the biofilm at the studied exemplar site than that of the cyanobacteria, i.e. 13 diatom species opposed to 9 cyanobacterial lineages. The non-phototrophic prokaryotic biofilm community is clearly different from the soil-derived community of the stream waters, and largely composed of flavobacteria, firmicutes, proteobacteria and actinobacteria. The exopolymeric biofilm matrix can be divided into three structural domains by fluorescence lectin-binding analysis. Seasonal and spatial variability of these structural EPS domains is low in the investigated streams. As indicated by microsensor data, biofilm photosynthesis is the driving mechanism in tufa stromatolite formation. However, photosynthesis-induced biofilm calcification accounts for only 10–20% of the total Ca
2+
loss in the streams, and occurs in parallel to inorganic precipitation driven by CO
2
-degassing within the water column and on biofilm-free surfaces. Annual stromatolite laminae reflect seasonal changes in temperature and light supply. The stable carbon isotope composition of the laminae is not affected by photosynthesis-induced microgradients, but mirrors that of the bulk water body only reflecting climate fluctuations. Tufa stromatolites with their cyanobacterial–photosynthesis-related calcification fabrics form an analogue to porostromate cyanobacterial stromatolites in fossil settings high in CaCO
3
mineral supersaturation but comparatively low in dissolved inorganic carbon. Here, the sum-effect of heterotrophic exopolymer-degradation and secondary Ca
2+
-release rather decreases calcite saturation, contrary to settings high in dissolved inorganic carbon such as soda lakes.
Some Fixed Point Properties of Self-Maps Constructed by Switched Sets of Primary Self-Maps on Normed Linear Spaces
Authors: De la Sen M 
Published: June 2010

AbstractThis paper is devoted to the investigation of the existence of fixed points in a normed linear space "Equation missing" endowed with a norm "Equation missing" for self-maps "Equation missing" from "Equation missing" to "Equation missing" which are constructed from a given class of so-called primary self- maps being also from "Equation missing" to "Equation missing". The construction of the self-maps of interest is performed via a so-called switching rule which is a piecewise-constant map from a set "Equation missing" to some finite subset of the positive integers or a sequence map which domain in some discrete subset of "Equation missing".
Metabolic Approach to the Enhancement of Antitumor Effect of Chemotherapy: a Key Role of Acetyl-l-Carnitine
Authors: Pisano Claudio , Vesci Loredana , Milazzo Ferdinando Maria , Guglielmi Mario Berardino , Foderà Rosanna , Barbarino Marcella , D'Incalci Maurizio , Zucchetti Massimo , Petrangolini Giovanna , Tortoreto Monica , Perego Paola , Zuco Valentina , Orlandi Augusto , Passeri Daniela , Carminati Paolo , Cavazza Claudio , Zunino Franco 
Published: June 2010

Abstract
Purpose: Acetyl-l-carnitine (ALC) plays a relevant role in energy metabolism and stress response because of its function in the complex metabolic system regulating the acetyl-CoA levels that provide a source of acetyl groups for metabolic and acetylation-regulated processes. Because acetylation may influence p53 activity/stability and, therefore, the response to platinum compounds, this study was designed to investigate the effect of ALC in combination with platinum compounds.
Experimental Design: The antiproliferative and antitumor activity studies were done in a panel of human tumor cell lines with functional or defective p53. The antimetastatic drug efficacy was investigated in the s.c. growing H460/M tumor subline, which is able to generate lung metastases.
Results: ALC enhanced the sensitivity to cisplatin of tumor cells with functional p53. The sensitization by ALC was reflected in an improved in vivo antitumor efficacy of the combination over cisplatin alone in wild-type p53 lung tumors. ALC did not increase the cisplatin efficacy in the p53-mutant SW620 tumor. ALC exhibited a significant antimetastatic activity, and this effect was better exploited in combination with the histone deacetylase inhibitor, ST3595. The in vivo ALC/cisplatin combination caused the activation of p53, associated with protein acetylation and induction of target genes.
Conclusions: ALC was effective in enhancing the antitumor potential of platinum compounds in wild-type p53 tumors. ALC, alone and in combination with a histone deacetylase inhibitor, exhibited an outstanding antimetastatic activity. Both effects, likely mediated by protein acetylation, may have implications for platinum-based therapy and combinations with histone deacetylase inhibitors. Clin Cancer Res; 16(15); 3944–53. ©2010 AACR.
Chronic Ambulatory Intracardiac Pressures and Future Heart Failure Events
Authors: Stevenson Lynne Warner , Zile Michael , Bennett Tom D. , Kueffer Fred J. , Jessup Mariell L. , Adamson Philip , Abraham William T. , Manda Ven , Bourge Robert C. 
Published: June 2010

Background—
Intracardiac pressures in heart failure (HF) have been measured in patients while supine in the hospital but change at home with posture and activity. The optimal level of chronic ambulatory pressure is unknown. This analysis compared chronic intracardiac pressures to later HF events and sought a threshold above which higher pressures conferred worse outcomes.

Methods and Results—
Median pressures were measured every 24 hours from continuous 8-minute segments for 6 months after implantation of hemodynamic monitors in 261 patients with New York Heart Association class III-IV HF in the Chronicle Offers Management to Patients with Advanced Signs and Symptoms of Heart Failure Study. Baseline and chronic daily medians of estimated pulmonary artery diastolic, right ventricular systolic, and right ventricular end-diastolic pressures were compared with HF event rate. The group median for chronic 24-hour estimated pulmonary artery diastolic pressure was 28 mm Hg (excluding 7 days before and after events). Despite weight-guided management, events occurred in 100 of 261 (38%) patients. Event risk increased progressively with higher chronic 24-hour estimated pulmonary artery diastolic pressure, from 20% at 18 mm Hg to 34% at 25 mm Hg and 56% at 30 mm Hg, with similar relations for right ventricular pressures. Among patients with baseline day median estimated pulmonary artery diastolic pressures of ≥25 mm Hg, event risk was 1.10/6 mo when they remained chronically ≥25 mm Hg, but risk fell to 0.47 when 24-hour pressures declined to <25 mm Hg for more than half of the days.

Conclusions—
Despite current management, many patients with advanced HF live on a plateau of high filling pressures from which later events occur. This risk is progressively higher with higher chronic ambulatory pressures. It is not known whether more targeted intervention could maintain lower chronic ambulatory pressures and better outcomes.
Dual task interference in estimating the risk of falls and measuring change: a comparative, psychometric study of four measurements
Authors: Hofheinz Martin , Schusterschitz Claudia 
Published: June 2010

Objective: The aim is to examine the validity and reliability of the Timed Up and Go Test with dual task for predicting the risk of falls. Standard values for the TUG with dual task were determined, taking account of age and gender. Design: Validation study Setting: Data was recorded for 120 volunteers in an outpatient physiotherapy centre. Subjects: The sample comprised 120 healthy men and women aged 60 to 87 years living at home. Twenty-three subjects selected at random were tested again, after one day and after one week, in order to ascertain the retest reliability. Main measures: Berg Balance Scale, times for Timed Up and Go Test with manual dual task (TUGman) and with cognitive dual task (TUGcog). Results: Strong correlations between the TUGman and the BBS (r = -0.72) and between the TUGcog and the BBS (r = -0.66) indicate high criterion validity. The retest reliability of the TUGman (rT1-T2 = 0.97 and rT1-T3 = 0.98) and TUGcog (rT1-T2 = 0.98 and rT1-T3 = 0.98) is very good. The intra-rater reliability is very high with an ICC = 0.99 for the TUGman and an ICC = 0.94 for the TUGcog. The mean time needed to perform the TUGman is 11.6 s (95% CI 11.2—11.9); the mean time needed to perform the TUGcog is 9.8 s (95% CI 9.5—10.2). Conclusions: The tests with dual task can be recommended because they possess high criterion validity and very good retest reliability. Faster and simpler performance of the TUG-DT is another factor in its favour.
A retrospective review of the management of asymptomatic retinal emboli identified during diabetic retinopathy screening: a case of inappropriate referral?
Authors: Wilde Craig , Rathore Deepa , Chen Hean-Choon 
Published: June 2010

Background Diabetic retinopathy screening generates many referrals of diabetic patients to ophthalmic clinics for incidental non-retinopathy pathology such as asymptomatic retinal emboli. Evidence exists that these patients have a 10 fold increased relative risk of stroke. With this in mind we evaluated our current management for this group. Methods A retrospective review was conducted for patients referred by the screening programme to the Eye Clinic, Derbyshire Royal Infirmary in 2008. Data were collected on modifiable cardiovascular risk factors, investigations conducted and treatment decisions. Results Nineteen patients were identified with asymptomatic retinal emboli: nine (47%) had known vascular disease; 13 patients (68%) were taking anti-platelet agents and 11 (58%) a statin. The mean blood pressure (BP) was 152/81 mmHg, but 10 patients (53%) had a BP > 140 mmHg and 47% were on antihypertensive medication. Carotid Doppler scans were performed on eight patients (42%), of whom two (25%) had stenosis over 70%. No new medications such as aspirin were started, nor any alteration made to anti-hypertensive medication. Conclusion As the eye clinic visit resulted in no change to the patients’ management, we feel that it may be more appropriate to refer these patients to a medical clinic to optimise their stroke risk reduction management. Br J Diabetes Vasc Dis 2010; 10:126—129
Association between circulating endothelial progenitor cells and hs-CRP in patients with diabetes
Authors: Koshikawa Megumi , Izawa Atsushi , Tomita Takeshi , Kumazaki Setsuo , Koyama Jun , Shimodaira Shigetaka , Ikeda Uichi 
Published: June 2010

Aim Endothelial progenitor cells (EPCs) play a critical role in maintaining endothelial function and might affect the progression of vascular disease. This study investigated the relationship between circulating EPCs and high-sensitivity C-reactive protein (hs-CRP) in patients with diabetes. Methods Our study population comprised 190 consecutive patients, with and without diabetes. To obtain EPC numbers, CD34+ and CD133+ cells in peripheral blood were counted by flow cytometry. Results Significantly higher hs-CRP levels were observed in patients with diabetes than in those without diabetes. However, the number of EPCs was significantly lower in diabetic patients and in patients with high hs-CRP levels. Patients with diabetes and high hs-CRP levels showed a marked decrease in the number of EPCs compared with non-diabetic patients with low hs-CRP levels. Conclusion These results suggest that inflammation leads to decreased circulating EPCs in patients with diabetes, which might be related to the pathogenesis of diabetic vascular disease.