bluuebunny/crossref_metadata_2025_split huggingface dataset:
Uplifting the Iwasawa
Authors: Franzen A. , Kaura P. , Misra A. , Ray R. 
Published: January 2006

AbstractThe Iwasawa manifold is uplifted to seven‐folds of eitherG2holonomy orSU(3) structure, explicit new metrics for the same having been constructed in this work. We uplift the Iwasawa manifold to aG2manifold through “size” deformation (of the Iwasawa metric), via Hitchin's Flow equations, showing also the impossibility of the uplift for “shape” and “size” deformations (of the Iwasawa metric). Using results of Dall'Agata and Prezas, Phys. Rev. D69, 066004 (2004) [arXiv:hep‐th/0311146] [1], we also uplift the Iwasawa manifold to a 7‐fold withSU(3) structure through “size” and “shape” deformations via generalisation of Hitchin's Flow equations. For seven‐folds withSU(3)‐structure, the result could be interpreted asM5‐branes wrapping two‐cycles embedded in the seven‐fold (as in [1]) ‐ a warped product of either a special hermitian six‐fold or a balanced six‐fold with the unit interval. There can be no uplift to seven‐folds ofSU(3) structure involving non‐trivial “size” and “shape” deformations (of the Iwasawa metric) retaining the “standard complex structure” ‐ the uplift generically makes one move in the space of almost complex structures such that one is neither at the standard complex structure point nor at the “edge”. Using the results of Konopelchenko and Landolfi, J. Geom. Phys.29, 319 (1999) [arXiv:math.DG/9804144] [2], we show that given two “shape deformation” functions, and the dilaton, one can construct a Riemann surface obtained via Weierstraß representation for the conformal immersion of a surface inRl, for a suitablel, with the condition of having conformal immersion being a quadric inCPl‐1.
Moduli stabilization in the heterotic/IIB discretuum
Authors: Curio G. , Krause A. , Lüst D. 
Published: January 2006

AbstractWe consider supersymmetric compactifications of type IIB and the weakly coupled heterotic string with G resp. H‐flux and gaugino condensation in a hidden sector included. We point out that proper inclusion of the non‐perturbative effects changes the Hodge structure of the allowed fluxes in type IIB significantly. In the heterotic theory it is known that, in contrast to the potential read off from dimensional reduction, the effective four‐dimensional description demands for consistency a non‐vanishing H2,1 component if a H3,0 component is already present balancing the condensate. The H2,1 component causes a non‐Kählerness of the underlying geometry whose moduli space is, however, not well‐understood. We show that the occurrence of H2,1 might actually be avoided by using a KKLT‐like two‐step procedure for moduli stabilization. Independently of the H2,1 issue one‐loop corrections to the gauge couplings were argued to cause a not well‐controlled strong coupling transition. This problem can be avoided as well when the effects of world‐sheet instantons are included. They will also stabilize the Kähler modulus what was accomplished by H2,1 before.
Predicting the redox state and secondary structure of cysteine residues in proteins using NMR chemical shifts
Authors: Wang Ching‐Cheng , Chen Jui‐Hung , Yin Shih‐His , Chuang Woei‐Jer 
Published: January 2006

AbstractWe report 2D cluster analyses of 1Hα, 1HN, 13Cα, and 13C′ versus 13Cβ NMR chemical shifts (CSs) that can be used to predict the redox state and secondary structure of cysteine residues in proteins. A database of cysteine 1Hα, 1Hβ2, 1Hβ3, 1HN, 13Cα, 13Cβ, 13C′, and 15NH CSs as a function of secondary structure and redox state was constructed from BioMagResBank entries. One‐dimensional statistical analysis showed that cysteine 1Hα, 1HN, 13Cα, 13C′, and 15NH CSs reflected the secondary structure, and that cysteine Cβ CS is extremely sensitive to the redox state. In contrast, cysteine 1Hβ CS was not correlated with its redox state or secondary structure. Two‐dimensional cluster analysis revealed that 2D Cα/Cβ, C′/Cβ, HN/Cβ, and Hα/Cβ clusters were helpful in distinguishing both the redox state and secondary structure of cysteine residues. Based on these results, we derived rules using a score matrix to predict the redox state and secondary structure of cysteines using their CSs. The score matrix predicts the redox state and secondary structure of cysteine residues in proteins with ∼90% accuracy. This suggests that the redox state and secondary structure of cysteine residues in peptides and proteins can be obtained from their CSs without recourse to nuclear Overhauser effect measurements. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Simultaneous determination of 109 pesticides in unpolished rice by a combination of gel permeation chromatography and Florisil column purification, and gas chromatography/mass spectrometry
Authors: Zhang Wei‐Guo , Chu Xiao‐Gang , Cai Hui‐Xia , An Juan , Li Chong‐Jiu 
Published: January 2006

AbstractA multi‐residue method is described for the simultaneous analysis of 109 pesticides with different properties in unpolished rice. The range covers organophosphorus, organochlorine, carbamate, and synthetic pyrethroid pesticides. The pesticides were extracted from the sample using ethyl acetate. Most higher molecular weight components such as lipids in the co‐extractives were removed by gel permeation chromatography (GPC) with a Bio‐bead SX‐3 column. A Florisil column with ethyl acetate/hexane as the eluting solvents was used for further cleanup. The pesticides were finally simultaneously determined by gas chromatography/mass spectrometry (GC/MS) in selective ion monitoring (SIM) mode. The average recoveries for most pesticides (spiked level 0.02, 0.1 and 1 µg/g) ranged from 70% to 110%, the relative standard deviation (RSD) was below 20% in every case, and the limit of detection (LOD) varied from 1 to 20 ng/g. Copyright © 2006 John Wiley & Sons, Ltd.
Citric acid traps to replace sulphuric acid in the ammonia diffusion of dilute water samples for 15N analysis
Authors: Schleppi Patrick , Bucher‐Wallin Inga , Saurer Matthias , Jäggi Maya , Landolt Werner 
Published: January 2006

AbstractThe analysis of 15N in aqueous samples requires the concentration of dissolved nitrogen (N) into a small volume that can be analysed by mass spectrometry. This is conveniently achieved by the NH3 diffusion technique, where NH is captured on small acidified filters enclosed in PTFE. NO can be analysed the same way by reducing it to NH with Devarda's alloy. H2SO4 is commonly used for the acidification of the filters. During combustion, however, this acid leads to the production of SO2 and elemental sulphur, which both have detrimental effects on the mass spectrometer. We propose here to replace H2SO4 with citric acid because it is combusted completely to CO2 and H2O in the elemental analyser before entering the mass spectrometer. Citric acid was found to give comparable results in terms of N recovery and 15N values, both for NH and for NO samples. Blank samples revealed that N contamination was slightly lower using citric instead of sulphuric acid as acidifier of the glass filters. NH samples first concentrated over cation‐exchange columns were strongly acidic and several methods were tested to raise the pH for the subsequent diffusion. These samples gave incomplete N recoveries, but this problem was independent of the acid used on the filters and of the final pH of the sample. Complete recovery was achieved only by increasing the volume of the eluate from the columns. Citric acid can thus generally be recommended instead of H2SO4 for ammonia diffusion. Copyright © 2006 John Wiley & Sons, Ltd.
Mobile robot motion estimation by 2D scan matching with genetic and iterative closest point algorithms
Authors: Martínez Jorge L. , González Javier , Morales Jesús , Mandow Anthony , García‐Cerezo Alfonso J. 
Published: January 2006

AbstractThe paper reports on mobile robot motion estimation based on matching points from successive two‐dimensional (2D) laser scans. This ego‐motion approach is well suited to unstructured and dynamic environments because it directly uses raw laser points rather than extracted features. We have analyzed the application of two methods that are very different in essence: (i) A 2D version of iterative closest point (ICP), which is widely used for surface registration; (ii) a genetic algorithm (GA), which is a novel approach for this kind of problem. Their performance in terms of real‐time applicability and accuracy has been compared in outdoor experiments with nonstop motion under diverse realistic navigation conditions. Based on this analysis, we propose a hybrid GA‐ICP algorithm that combines the best characteristics of these pure methods. The experiments have been carried out with the tracked mobile robot Auriga‐α and an on‐board 2D laser scanner. © 2006 Wiley Periodicals, Inc.
Online turnover‐free control for a mobile agent with a terrain prediction sensor
Authors: Park Jae Byung , Lee Jeong Hee , Lee Beom Hee 
Published: January 2006

AbstractThis paper proposes a turnover‐free control method for a teleoperated mobile agent (or vehicle) moving through uneven terrain. The teleoperated agent is primarily driven by an operator at a remote site and is able to react autonomously when a possible turnover is predicted. In order to predict the turnover, a low‐cost terrain prediction sensor has been developed using a camera vision with a structured laser light. Since it is difficult for an operator to predict the reactive motion of the agent, a force reflection technique with a force feedback joystick is employed to intuitively recognize the inconsistency between the intended motion and the reactive motion of the agent. Finally, to verify the feasibility and effectiveness of the proposed method, experiments with the ROBHAZ‐DT (actual mobile agent) have been carried out. In the experiments, the operator could recognize the reactive motion of the agent for turnover prevention through force reflection while the agent was moving on slopped terrain. © 2006 Wiley Periodicals, Inc.
A demand‐based perspective on sustainable competitive advantage
Authors: Adner Ron , Zemsky Peter 
Published: January 2006

AbstractWe develop an approach to analyzing the sustainability of competitive advantage that emphasizes demand‐side factors. We extend the added‐value approach to business strategy by introducing an explicit treatment of how firms create value for consumers. This allows us to characterize how consumer heterogeneity and marginal utility from performance improvements on the demand side interact with resource heterogeneity and improving technologies on the supply side. Using this approach, we address a variety of questions including whether technology substitutions will be permanent or transitory; the sequence in which new technologies attack different market segments; how rents from different types of resources change over time; whether decreasing marginal utility and imitation give rise to similar rent profiles; the extent of synergies within a firm's resource portfolio; the emergence of new generic strategies; and the conditions that support strategic diversity in a market. Our focus on consumer utility and value creation complements the traditional focus in the strategy literature on competition and value capture. Copyright © 2006 John Wiley & Sons, Ltd.
Increasing the flexural modulus of rigid PVC at elevated temperatures
Authors: Wiebking Henry E. 
Published: January 2006

AbstractThe use of PVC building products in hot climates has demonstrated the need for formulations that exhibit increased stiffness at elevated temperatures. Talc has been used as an additive to increase flexural modulus but this approach can produce an unacceptable drop in impact strength. This report presents the results of laboratory work designed to find ways to increase the stiffness of rigid PVC compounds at elevated temperatures while maintaining their room temperature impact performance. J. VINYL. ADDIT. TECHNOL., 12:37–40, 2006. © 2006 Society of Plastics Engineers
Inter-identity amnesia in dissociative identity disorder: a simulated memory impairment?
Authors: HUNTJENS RAFAËLE J. C. , PETERS MADELON L. , WOERTMAN LIESBETH , BOVENSCHEN LOES M. , MARTIN ROY C. , POSTMA ALBERT 
Published: January 2006

Background. Although included in the current edition of the DSM, there does not seem to be consensus among mental health professionals regarding the diagnostic status and scientific validity of dissociative identity disorder (DID). This study was aimed at the detection of simulation of inter-identity amnesia in DID.Method. A sample of 22 DID patients was included, together with a matched control sample of subjects instructed to simulate inter-identity amnesia, a guessor group that had no knowledge of the stimulus material and a normal control group. A multiple-choice recognition test was included. The rate of incorrect answers was determined. Moreover, the specific simulation strategy used was examined by providing subjects with a range of choices that varied in extent of disagreement with the correct answer and determining whether plausible or implausible answer alternatives were selected.Results. On the recognition test DID patients selected incorrect answers above chance like simulators. Patients thus seem to use their knowledge of the correct answer in determining their given answer. They were not characterized by a well-thought-out simulating behaviour style, as indicated by the differences in selection of specific answer alternatives found between patients and simulators.Conclusions. DID patients were found not to be characterized by an actual memory retrieval inability, in contrast to their subjective reports. Instead, it is suggested that DID may more accurately be considered a disorder characterized by meta-memory problems, holding incorrect beliefs about their own memory functioning.
The Singing Neanderthals: the Origins of Music, Language, Mind and Body, by Steven Mithen. London: Weidenfeld & Nicholson, 2005. ISBN 0-297-64317-7 hardback £20 & US$25.2; ix+374 pp.
Authors: Mithen Steven , Morley Iain , Wray Alison , Tallerman Maggie , Gamble Clive 
Published: January 2006

Why are humans musical? Why do people in all cultures sing or play instruments? Why do we appear to have specialized neurological apparatus for hearing and interpreting music as distinct from other sounds? And how does our musicality relate to language and to our evolutionary history?Anthropologists and archaeologists have paid little attention to the origin of music and musicality — far less than for either language or ‘art’. While art has been seen as an index of cognitive complexity and language as an essential tool of communication, music has suffered from our perception that it is an epiphenomenal ‘leisure activity’, and archaeologically inaccessible to boot. Nothing could be further from the truth, according to Steven Mithen; music is integral to human social life, he argues, and we can investigate its ancestry with the same rich range of analyses — neurological, physiological, ethnographic, linguistic, ethological and even archaeological — which have been deployed to study language. In The Singing Neanderthals Steven Mithen poses these questions and proposes a bold hypothesis to answer them. Mithen argues that musicality is a fundamental part of being human, that this capacity is of great antiquity, and that a holistic protolanguage of musical emotive expression predates language and was an essential precursor to it.This is an argument with implications which extend far beyond the mere origins of music itself into the very motives of human origins. Any argument of such range is bound to attract discussion and critique; we here present commentaries by archaeologists Clive Gamble and Iain Morley and linguists Alison Wray and Maggie Tallerman, along with Mithen's response to them. Whether right or wrong, Mithen has raised fascinating and important issues. And it adds a great deal of charm to the time-honoured, perhaps shopworn image of the Neanderthals shambling ineffectively through the pages of Pleistocene prehistory to imagine them humming, crooning or belting out a cappella harmonies as they went.
Determinants of AQP6 trafficking to intracellular sites versus the plasma membrane in transfected mammalian cells
Authors: Beitz Eric , Liu Kun , Ikeda Masahiro , Guggino William B. , Agre Peter , Yasui Masato 
Published: January 2006

Background information. Most AQPs (aquaporins) function at the plasma membrane, however AQP6 is exclusively localized to membranes of intracellular vesicles in acid‐secreting type‐A intercalated cells of renal collecting ducts. The intracellular distribution indicates that AQP6 has a function distinct from trans‐epithelial water movement.Results. We show by mutational analyses and immunofluorescence that the N‐terminus of AQP6 is a determinant for its intracellular localization. Presence or absence at the plasma membrane of AQP6 constructs was confirmed by electrophysiological methods. Addition of a GFP (green fluorescent protein) or a HA (haemagglutinin) epitope tag (GFP—AQP6 or HA—AQP6) to the N‐terminus of AQP6, directed AQP6 to the plasma membranes of transfected Madin—Darby canine kidney cells. In contrast, addition of a GFP tag to the C‐terminus (AQP6–GFP) caused the protein to remain intracellular, similar to untagged wild‐type AQP6. Replacement of the N‐terminus of AQP6 by that of AQP1 also directed AQP6 to the plasma membranes, whereas the N‐terminus of AQP6 retained AQP1 in cytosolic sites.Conclusion. Our results suggest that the N‐terminus of AQP6 is critical for trafficking of the protein to the intracellular sites. Moreover, our studies provide an approach for future identification of proteins involved in vesicle sorting in the acid‐secreting type‐A intercalated cells.
Extracellular NAD+ regulates intracellular calcium levels and induces activation of human granulocytes
Authors: Bruzzone Santina , Moreschi Iliana , Guida Lucrezia , Usai Cesare , Zocchi Elena , De Flora Antonio 
Published: January 2006

β-NAD+e (extracellular β-NAD+), present at nanomolar levels in human plasma, has been implicated in the regulation of [Ca2+]i (the intracellular calcium concentration) in various cell types, including blood cells, by means of different mechanisms. Here, we demonstrate that micromolar NAD+e (both the α and the β extracellular NAD+ forms) induces a sustained [Ca2+]i increase in human granulocytes by triggering the following cascade of causally related events: (i) activation of adenylate cyclase and overproduction of cAMP; (ii) activation of protein kinase A; (iii) stimulation of ADP-ribosyl cyclase activity and consequent overproduction of cADP-ribose, a universal Ca2+ mobilizer; and (iv) influx of extracellular Ca2+. The NAD+e-triggered [Ca2+]i elevation translates into granulocyte activation, i.e. superoxide and nitric oxide generation, and enhanced chemotaxis in response to 0.1–10 μM NAD+e. Thus extracellular β-NAD+e behaves as a novel pro-inflammatory cytokine, stimulating human granulocytes and potentially recruiting them at sites of inflammation.
Effect of chronic N-acetylcysteine treatment on the development of spontaneous hypertension
Authors: Pecháňová Olga , Zicha Josef , Kojšová Stanislava , Dobešová Zdenka , Jendeková Lýdia , Kuneš Jaroslav 
Published: January 2006

The imbalance between NO (nitric oxide) and ROS (reactive oxygen species) is an important factor in the development of hypertension. The aim of the present study was to determine the preventive and therapeutic effects of NAC (N-acetylcysteine) in SHRs (spontaneously hypertensive rats). Young and adult SHRs and WKY (Wistar–Kyoto) rats were treated with NAC (20 g/l in the drinking water). After 8 weeks of treatment, BP (blood pressure) and NOS (NO synthase) activity, conjugated dienes and GSH (reduced glutathione) in the kidney and left ventricle were determined. Protein expression of eNOS (endothelial NOS), inducible NOS and NF-κB (nuclear factor κB) were also determined in the left ventricle and kidney. Chronic NAC treatment partially attenuated the rise in BP in young SHRs (179±6 compared with 210±8 mmHg in untreated animals), but it had no significant effect on BP in adult SHRs. The antioxidant action of NAC, measured as a decrease of the concentration of conjugated dienes or inhibition of NF-κB expression, was greater in young than in adult SHRs. Similarly, eNOS protein expression was attenuated more in young than in adult SHRs, although NAC treatment increased NOS activity to a similar extent in both young and adult rats. In conclusion, both decreased ROS production and increased NOS activity appear to participate in the BP changes after NAC treatment in young SHRs. In adult SHRs with established hypertension, however, the secondary alterations (such as pronounced structural remodelling of resistance vessels) might attenuate the therapeutic effect of NAC.
Endothelial dysfunction in growth hormone transgenic mice
Authors: Andersson Irene J. , Johansson Maria E. , Wickman Anna , Bohlooly-Y Mohammad , Klintland Natalia , Caidahl Kenneth , Gustafsson Maria , Borén Jan , Gan Li-ming , Bergström Göran 
Published: January 2006

Acromegaly [overproduction of GH (growth hormone)] is associated with cardiovascular disease. Transgenic mice overexpressing bGH (bovine GH) develop hypertension and hypercholesterolaemia and could be a model for cardiovascular disease in acromegaly. The aims of the present study were to investigate the effects of excess GH on vascular function and to test whether oxidative stress affects endothelial function in bGH transgenic mice. We studied the ACh (acetylcholine)-induced relaxation response in aortic and carotid rings of young (9–11 weeks) and aged (22–24 weeks) female bGH transgenic mice and littermate control mice, without and with the addition of a free radical scavenger {MnTBAP [Mn(III)tetrakis(4-benzoic acid)porphyrin chloride]}. We also measured mRNA levels of eNOS (endothelial nitric oxide synthase) and EC-SOD (extracellular superoxide dismutase). Intracellular superoxide anion production in the vascular wall was estimated using a dihydroethidium probe. Carotid arteries from bGH transgenic mice had an impaired ACh-induced relaxation response (young, 46±7% compared with 69±8%; aged, 52±5% compared with 80±3%; P&lt;0.05), whereas endothelial function in aorta was intact in young but impaired in aged bGH transgenic mice. Endothelial dysfunction was corrected by addition of MnTBAP in carotid arteries from young mice and in aortas from aged mice; however, MnTBAP did not correct endothelial dysfunction in carotid arteries from aged bGH transgenic mice. There was no difference in intracellular superoxide anion production between bGH transgenic mice and control mice, whereas mRNA expression of EC-SOD and eNOS was increased in aortas from young bGH transgenic mice compared with control mice (P&lt;0.05). We interpret these data to suggest that bGH overexpression is associated with a time- and vessel-specific deterioration in endothelial function, initially caused by increased oxidative stress and later by other alterations in vascular function.