bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine
Authors: Peese Kevin M. , Gin David Y.
Published: November 2007

A dual cycloaddition strategy for the synthesis of the hetisine alkaloids has been developed, illustrated by a concise asymmetric total synthesis of (+)‐nominine (7). The approach relies on an early‐stage intramolecular 1,3‐dipolar cycloaddition of a 4‐oxido‐isoquinolinium betaine dipole with an ene–nitrile dipolarophile. Subsequent late‐stage pyrrolidine‐induced dienamine isomerization/Diels–Alder cascade allows for rapid construction of the carbonnitrogen polycyclic skeleton within this class of C20‐diterpenoid alkaloids.
The contingent influence of organizational capabilities on proactive environmental strategy in the service sector: An analysis of North American and European ski resorts
Authors: Sharma Sanjay , Aragón‐Correa J. Alberto , Rueda‐Manzanares Antonio
Published: November 2007

Our study of 134 North American and European ski resorts examines the influence of externally focused organizational capabilities on the generation of proactive environmental strategies under contingent effects of uncertainty in the general business environment. We find that the capabilities of strategic proactivity and continuous innovation are associated with proactive environmental strategies. Managerial perceptions of uncertainty in the general business environment moderate the deployment of the capability of continuous innovation at all levels of uncertainty and stakeholder engagement at low and average levels of uncertainty. The study contributes to the resource‐based view (RBV) by illuminating an important contingency under which capabilities are likely to be deployed to generate a proactive corporate strategy. Copyright © 2007 ASAC. Published by John Wiley & Sons, Ltd.
Comparison of the efficacy and safety of miconazole 50‐mg mucoadhesive buccal tablets with miconazole 500‐mg gel in the treatment of oropharyngeal candidiasis
Authors: Bensadoun Rene‐Jean , Daoud Jamel , El Gueddari Brahim , Bastit Laurent , Gourmet Rene , Rosikon Andrzej , Allavena Christophe , Céruse Philippe , Calais Gilles , Attali Pierre
Published: November 2007

BACKGROUND.

Topical antifungal treatments are recommended but rarely used as first‐line therapy for oropharyngeal candidiasis (OPC) in patients with cancer. Miconazole Lauriad 50‐mg mucoadhesive buccal tablet (MBT) Loramyc reportedly delivered rapid and prolonged, effective concentrations of miconazole in the mouth. The objective of the current study was to compare MBT with miconazole 500‐mg oral gel (MOG) in patients with head and neck cancer.

METHODS.

Two hundred eighty‐two patients with head and neck cancer received a 14‐day treatment of either single‐dose MBT or MOG administered in 4 divided doses. The primary endpoint was clinical success at Day 14, and secondary endpoints included clinical success at Day 7, clinical cure, improvement in clinical symptoms, mycologic cure, recurrence rate, and safety.

RESULTS.

The success rate was statistically not inferior (P < .0001) in the MBT population to the rate observed in the MOG group (56% vs 49%, respectively; P < .0001). After adjustment for the extent of lesions and salivary secretions, a trend toward superiority was observed in favor of MBT (P = .13), particularly among patients with multiple lesions (P = .013). Results for secondary endpoints were comparable to those observed for the primary endpoint. Compliance with MBT was excellent, and >80% of patients completed treatment. Both treatments were safe.

CONCLUSIONS.

The success rate of MBT Loramyc was significantly not inferior to that of MOG in the treatment of cancer patients with OPC; and, after adjusting for prognostic variables, it was more effective than MOG. MBT was well tolerated and, thus, may be recommended as first‐line treatment in cancer patients who have OPC as an alternative to systemic antifungal agents. Cancer 2008. © 2007 American Cancer Society.
Two‐sided fluorescence resonance energy transfer for assessing molecular interactions of up to three distinct species in confocal microscopy
Authors: Fazekas Zsolt , Petrás Miklós , Fábián Ákos , Pályi‐Krekk Zsuzsanna , Nagy Péter , Damjanovich Sándor , Vereb György , Szöllősi János
Published: November 2007

The role of the expression patterns of proteins involved in oncogenesis can be understood after characterizing their multimolecular interactions. Conventional FRET methods permit the analysis of interaction between two molecular species at the most, which necessitates the introduction of new approaches for studying multicomponent signaling complexes. Flow cytometric as well as microscopic donor (dbFRET) and acceptor (abFRET) photobleaching FRET measurements were performed to determine the association states of ErbB2, β1‐integrin, and CD44 receptors. Based on consecutively applied abFRET and dbFRET methods (two‐sided FRET), the relationship of β1‐integrin–ErbB2 heteroassociation to ErbB2 homoassociation and of β1‐integrin–ErbB2 heteroassociation to ErbB2–CD44 heteroassociation was studied by correlating pixel‐by‐pixel FRET values of the corresponding abFRET and dbFRET images in contour plots. Anticorrelation was observed between β1‐integrin–ErbB2 heteroassociation and ErbB2 homoassociation on trastuzumab sensitive N87 and SK‐BR‐3 cells, while modest positive correlation was found between β1‐integrin–ErbB2 and ErbB2–CD44 heteroassociation on trastuzumab resistant MKN‐7 cells. The FRET efficiency values of β1‐integrin–ErbB2 heteroassociation were markedly higher at the focal adhesion regions on attached cells than those measured by flow cytometry on detached cells. In conclusion, we implemented an experimental set‐up termed two‐sided FRET for correlating two pairwise interactions of three arbitrarily chosen molecular species. On the basis of our results, we assume that the homoassociation state of ErbB2 is dynamically modulated by its interaction with β1‐integrins. © 2007 International Society for Analytical Cytology
Testing NMDA receptor block as a therapeutic strategy for reducing ischaemic damage to CNS white matter
Authors: Bakiri Yamina , Hamilton Nicola B. , Káradóttir Ragnhildur , Attwell David
Published: November 2007

Damage to oligodendrocytes caused by glutamate release contributes to mental or physical handicap in periventricular leukomalacia, spinal cord injury, multiple sclerosis, and stroke, and has been attributed to activation of AMPA/kainate receptors. However, glutamate also activates unusual NMDA receptors in oligodendrocytes, which can generate an ion influx even at the resting potential in a physiological [Mg2+]. Here, we show that the clinically licensed NMDA receptor antagonist memantine blocks oligodendrocyte NMDA receptors at concentrations achieved therapeutically. Simulated ischaemia released glutamate which activated NMDA receptors, as well as AMPA/kainate receptors, on mature and precursor oligodendrocytes. Although blocking AMPA/kainate receptors alone during ischaemia had no effect, combining memantine with an AMPA/kainate receptor blocker, or applying the NMDA blocker MK‐801 alone, improved recovery of the action potential in myelinated axons after the ischaemia. These data suggest NMDA receptor blockers as a potentially useful treatment for some white matter diseases and define conditions under which these blockers may be useful therapeutically. Our results highlight the importance of developing new antagonists selective for oligodendrocyte NMDA receptors based on their difference in subunit structure from most neuronal NMDA receptors. © 2007 Wiley‐Liss, Inc.
Classification and Prognosis of Intrahepatic Biliary Stricture After Liver Transplantation
Authors: Lee Hae Won , Suh Kyung-Suk , Shin Woo Young , Cho Eung-Ho , Yi Nam-Joon , Lee Jeong Min , Han Joon Koo , Lee Kuhn Uk
Published: November 2007

Intrahepatic biliary stricture (IHBS) after liver transplantation (LT) may develop in patients with hepatic artery thrombosis, chronic rejection, or ABO incompatibility, as well as in patients with prolonged warm ischemia in non-heart-beating donor (NHBD) LT. However, the clinical course and methods of management have not been well defined for IHBSs to date. Thus, the purpose of this study was to provide a classification of post-LT IHBS and to investigate patient prognosis. Forty-four patients who developed IHBS after NHBD LT were enrolled. On the basis of the cholangiographic appearance, patients were classified into 4 groups: unilateral focal (UF, n = 8), confluence (CO, n = 10), bilateral multifocal (BM, n = 21), and diffuse necrosis (DN, n = 5). The UF type was defined as cases with stricture only in the segmental branch of the unilateral hemiliver; the CO type in cases with several strictures at confluence level; and the BM type in cases with multiple strictures bilaterally. Cases with diffuse obliteration of peripheral ducts or destruction of the central architectural integrity, over a long segment, were classified as the DN type. Five patients with the CO type required several interventions requiring biliary dilatation, yet all patients with the UF or CO type had a good prognosis. Among the patients with the BM type, 3 patients (14.3%) died or underwent retransplantation due to biliary complications, and 7 (33.3%) required repeated interventions for >1 year without improvement. Moreover, among 5 patients classified as the DN type, 1 (20%) died of biliary sepsis, 2 (40%) underwent retransplantation, and the remaining 2 (40%) did not recover from persistent jaundice and life-threatening cholangitis despite multiple interventions. In conclusion, all patients classified as UF or CO had a good outcome with or without additional interventions. However, all patients with the DN type and about half the patients with the BM type did not recover from life-threatening complications, despite repeated aggressive interventions; early retransplantation was therefore the only treatment option for these patients. Liver Transpl 13:1736–1742, 2007. © 2007 AASLD.
Liver Retransplantation of Patients With Hepatitis C Infection Is Associated With Acceptable Patient and Graft Survival
Authors: Ghabril Marwan , Dickson Rolland C. , Machicao Victor I. , Aranda-Michel Jaime , Keaveny Andrew , Rosser Barry , Bonatti Hugo , Krishna Murli , Yataco Maria , Satyanarayana Raj , Harnois Denise , Hewitt Winston , Willingham Darin D. , Grewal Hani , Hughes Christopher B. , Nguyen Justin
Published: November 2007

Infection with hepatitis C virus (HCV) is the leading cause of liver transplantation (LT), while liver retransplantation (RT) for HCV is controversial as a result of concerns over poor outcomes. We sought to compare patient and graft survival after RT in patients with and without HCV. We performed a retrospective chart review of all patients undergoing RT at our center between February 1998 and April 2004. Indications for RT, HCV status, patient, and donor characteristics, laboratory values, and hospitalization status at RT were collected. A total of 108 patients (48 HCV and 60 non-HCV) underwent RT during the study period, with mean post-RT follow-up of 1,096 days (range, 0–2,888 days). Grafts from donors aged >60 years were used less frequently in HCV patients at RT (6%) compared with LT (47%), P < 0.001. There was no difference between HCV vs. non-HCV patients in 1- and 3-year patient survival (respectively, 79% vs. 63%, and 71% vs. 63%) and graft survival (respectively, 67% vs. 66%, and 59% vs. 56%). Post-RT mortality and graft failure in HCV patients occurred within the first year in 89% of patients, and 83% were unrelated to HCV recurrence. We conclude that patients should not be excluded from consideration for retransplantation solely on the basis of a diagnosis of HCV. Liver Transpl 13:1717–1727, 2007. © 2007 AASLD.
Macromol. Chem. Phys. 23/2007
Authors: Chen Kai , Harris Kehley , Vyazovkin Sergey
Published: November 2007

Back Cover: Kinetic analysis of the thermal behavior of atactic, syndiotactic, and isotactic polystyrene suggests that the larger stability of the isotactic form is associated with an increase in the activation energy and a decrease in the values of the rate constant as well as the reaction model and can be explained by intramolecular confinement. Further details can be found in the article by K. Chen, K. Harris, and S. Vyazovkin* on page 2525.
Telomere length and risk of Parkinson's disease
Authors: Wang Hao , Chen Honglei , Gao Xiang , McGrath Monica , Deer Dwayne , De Vivo Immaculata , Schwarzschild Michael A. , Ascherio Alberto
Published: November 2007

We investigated whether telomere length was associated with the risk of Parkinson's disease (PD) in a case‐control study (96 cases and 172 age‐matched controls) nested within the Health Professionals Follow‐up Study. Relative ratio of telomere repeat copy number to single‐gene copy number in peripheral blood leukocytes was determined by quantitative real time PCR. Men with shorter telomeres had a lower PD risk (multivariate adjusted relative risk for the lowest vs. the highest quartile 0.33; 95% confidence interval: 0.12–0.90). Our results suggest that, contrary to telomere attrition observed in several aging‐related diseases, shorter telomeres are not associated with an increased risk of PD. © 2007 Movement Disorder Society
A catheter tracking method using reverse polarization for MR‐guided interventions
Authors: Celik Haydar , Ulutürk Aslı , Talı Turgut , Atalar Ergin
Published: November 2007

To conduct interventional procedures in MRI, reliable visualization of interventional devices such as catheters is necessary. For this purpose, the use of inductively‐coupled radio frequency (ICRF) coils has been proposed. Without a wired connection, the signal around the ICRF coil is amplified, enabling catheters to be visualized. The wireless connection allows easy handling of catheters, in some pulse sequences, however, it might be difficult to differentiate the catheters from anatomical background information. In this work, a novel ICRF coil visualization method, which allows separation of the catheter and the anatomical information by using the reverse and forward polarization modes of a coil, is proposed. This method allows images of the anatomy and the catheter to be combined into a color‐coded image. First, an ICRF coil with decoupling diodes was constructed; we call this a receive‐coupled RF (RCRF) coil. The RF safety profile of the RCRF coil is shown to be better than the ICRF coil. Second, to demonstrate the feasibility of this method, a receive‐only birdcage coil without a hybrid coupler was constructed and then connected to a scanner as a two‐channel phased‐array coil. MR signals acquired from two channels were added after phase adjustments to create the reverse and forward polarization mode images. The reverse polarization mode image contained signal only from the RCRF coil, but the forward polarization mode displayed both anatomical information and the RCRF coil. The performance of this novel tracking method was tested in phantom and animal experiments. Color‐coded images demonstrate the feasibility of the method to track catheters using RCRF coils. Magn Reson Med 58:1224–1231, 2007. © 2007 Wiley‐Liss, Inc.
Axonal injury detected by in vivo diffusion tensor imaging correlates with neurological disability in a mouse model of multiple sclerosis
Authors: Budde Matthew D. , Kim Joong Hee , Liang Hsiao‐Fang , Russell John H. , Cross Anne H. , Song Sheng‐Kwei
Published: November 2007

Recent studies have suggested that axonal damage, and not demyelination, is the primary cause of long‐term neurological impairment in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). The axial and radial diffusivities derived from diffusion tensor imaging have shown promise as non‐invasive surrogate markers of axonal damage and demyelination, respectively. In this study, in vivo diffusion tensor imaging of the spinal cords from mice with chronic EAE was performed to determine if axial diffusivity correlated with neurological disability in EAE assessed by the commonly used clinical scoring system. Axial diffusivity in the ventrolateral white matter showed a significant negative correlation with EAE clinical score and was significantly lower in mice with severe EAE than in mice with moderate EAE. Furthermore, the greater decreases in axial diffusivity were associated with greater amounts of axonal damage, as confirmed by quantitative staining for non‐phosphorylated neurofilaments (SMI32). Radial diffusivity and relative anisotropy could not distinguish between the groups of mice with moderate EAE and those with severe EAE. The results further the notion that axial diffusivity is a non‐invasive marker of axonal damage in white matter and could provide the necessary link between pathology and neurological disability. Copyright © 2007 John Wiley & Sons, Ltd.
Eine Fußgängerbrücke mit einer Spannweite von 230 m
Authors: Strobl Wolfgang , Kovacs Imre , Andrä Hans‐Peter , Häberle Uwe
Published: November 2007

Im Südwesten Deutschlands wurde im März 2006 die “Dreiländerbrücke”, eine Fußgängerbrücke zwischen Weil am Rhein (D) und Huningue (F), mit einer Rekordspannweite von 230m eröffnet. Die Brücke verbessert die Infrastruktur der Region und verbindet die Menschen über Grenzen hinweg.

Der Entwurf eines äußerst schlanken, asymmetrischen Bogens ist eine eindeutige Geste, die eine starke Verbindung zwischen den beiden Ländern Deutschland und Frankreich symbolisiert und gleichzeitig die Sichtbeziehung beibehält.
Einsatz des nichtrostenden Duplex‐Stahls 1.4362 als preisgünstige Alternative im Bauwesen
Authors: Eich Gerd , Burkert Annette , Burkert Andreas , Mietz Jürgen
Published: November 2007

Aufgrund der in den letzten Jahren stark angestiegenen Rohstoffpreise sind die im Bauwesen häufig eingesetzten nichtrostenden Standardaustenite in vielen Fällen nicht mehr wettbewerbsfähig. Eine deutlich kostengünstigere Alternative stellt der Duplex‐Stahl 1.4362 dar, der bisher aber noch nicht bauaufsichtlich zugelassen ist. Mit Hilfe von Auslagerungsversuchen sowie elektrochemischen Untersuchungen sollte das Korrosionsverhalten dieses Werkstoffs unter neutralen bis leicht sauren, chloridhaltigen Umgebungsbedingungen, wie sie in vielen Bereichen des Bauwesens vorkommen, geklärt werden. Insgesamt belegen die Ergebnisse, dass der kostengünstigere Werkstoff 1.4362 für baupraktische Anwendungen eine Alternative für Anwendungen darstellen kann, in denen bisher die Werkstoffe 1.4404 oder 1.4571 eingesetzt wurden.
Ezetimibe improves liver steatosis and insulin resistance in obese rat model of metabolic syndrome
Authors: Deushi Michiyo , Nomura Mitsunori , Kawakami Akio , Haraguchi Mihoko , Ito Mizuho , Okazaki Mitsuyo , Ishii Hideto , Yoshida Masayuki
Published: November 2007

Non‐alcoholic fatty liver disease (NAFLD) is associated with the metabolic syndrome characterized by dislipidemia and insulin resistance. We hypothesized that ezetimibe, an inhibitor of NPC1L1, improves these metabolic disorders in Zucker obese fatty rats (ZOF). Ezetimibe significantly lowered total cholesterol and triglycerides in ZOF with prominent reduction in the remnant lipoprotein fraction and small dense low density lipoprotein fraction. Moreover, lipid deposition and fibrosis of liver were decreased by ezetimibe. Interestingly, ezetimibe improved insulin and plasma glucose response after intraperitoneal glucose injection. Further, ezetimibe enhanced insulin signaling in cultured hepatocytes. Our results indicate the potential of ezetimibe in treating the metabolic syndrome and NAFLD.
The development and evaluation of a novel computer program to assess previous-day dietary and physical activity behaviours in school children: The Synchronised Nutrition and Activity ProgramTM(SNAPTM)
Authors: Moore Helen J. , Ells Louisa J. , McLure Sally A. , Crooks Sean , Cumbor David , Summerbell Carolyn D. , Batterham Alan M.
Published: November 2007

Self-report recall questionnaires used to measure physical activity and dietary intake in children can be labour intensive and monotonous and tend to focus on either dietary intake or physical activity. The web-based software, Synchronised Nutrition and Activity ProgramTM(SNAPTM), was developed to produce a novel, simple, quick and engaging method of assessing energy balance-related behaviours at a population level, combining principles from new and existing 24 h recall methodologies, set within a user-friendly interface. Dietary intake was measured using counts for twenty-one food groups and physical activity levels were measured in min of moderate to vigorous physical activity (MVPA). A combination of the mean difference between methods, type II regression and non-parametric limits of agreement techniques were used to examine the accuracy and precision of SNAPTM. Method comparison analyses demonstrated a good agreement for both dietary intake and physical activity behaviours. For dietary variables, accuracy of SNAPTM(mean difference) was within ± 1 count for the majority of food groups. The proportion of the sample with between-method agreement within ± 1 count ranged from 0·40 to 0·99. For min of MVPA, there was no substantial fixed or proportional bias, and a mean difference between methods (SNAPTM– accelerometry) of − 9 min. SNAPTMprovides a quick, accurate, low-burden, cost-effective and engaging method of assessing energy balance behaviours at a population level. Tools such as SNAPTM, which exploit the popularity, privacy and engagement of the computer interface, and linkages with other datasets, could make a substantial contribution to future public health monitoring and research.
Authors: McGhee Michael
Published: November 2007

This is a powerful and learned meditation on Christianity by a senior Irish theologian, and the main reason it should be noticed in a journal of philosophy is that James Mackey conceives theology as fundamentally philosophical in the way it reflects on and develops our ideas about the sources and nature of being and conduct as they have been articulated in myth, symbol and poetry, as well as more abstractly in metaphysics. On this view the philosophical aspect of theology is displayed no less in the scrutiny and interpretation of that myth, symbol and poetry than in the more narrowly focussed field of natural theology as this has come to be practised by recent analytic philosophers—a field, indeed, which might well be thought, on the evidence of this book, to depend upon and be undermined by an uncritical reception of discredited readings of the imagery of the creation myth (see 381). It is appropriate—and something of a relief—that in his nuanced and compelling reflections on that myth Mackey's philosophical temper leads him to stress the importance of the creative imagination, particularly that of the poet, who is ‘the seer, the prophet, the visionary, who sees so deeply into the fabric of reality that the ways of the Creator with creation are revealed in the ensuing poetry, and with a power and a clarity seldom equalled in other forms’ (35). Indeed he opens his chapter on Creation by highlighting the importance of the metaphors and imagery which are to be his theme and by which myth is constituted and ‘reality’ mediated. He refers to them as ‘configurations through which reality first rewards the attentive, or more precisely the contemplative mind’ (29) and remarks that at its outer limit ‘imagination … ends up by telling a cosmic story, resulting in nothing less than a cosmic myth’ (ibid.). One important implication of this fertile approach is that it also requires engagement with a question about the nature of the relationship between myth and metaphysics: after all, some philosophers still incline to the view that metaphysics underwrites and validates what the poet ‘sees’. However, it provokes another question, which is at least as important, about the status of theism as itself perhaps ‘a cosmic myth’. What kind of ‘reality’ is revealed by the poet? Are ‘the ways of the Creator with his creation’ the reality (in some way independently ascertained) whose nature is revealed by the poet? Or is it, rather, that ‘the ways of the Creator with his creation’ are part of a particular configuration of images by which the poets widen our perceptions and articulate their wonder at the world of creative forces in the form of story-telling, both mythopoeic and metaphysical.
Relation between rock uplift and denudation from cosmogenic nuclides in river sediment in the Central Alps of Switzerland
Authors: Wittmann Hella , von Blanckenburg Friedhelm , Kruesmann Tina , Norton Kevin P. , Kubik Peter W.
Published: November 2007

A north‐south traverse through the Swiss Central Alps reveals that denudation rates correlate with recent rock uplift rates in both magnitude and spatial distribution. This result emerges from a study of in situ–produced cosmogenic 10Be in riverborne quartz in Central Alpine catchments. As a prerequisite, we took care to investigate the potential influence of shielding from cosmic rays due to snow, glaciers, and topographic obstructions; to calculate a possible memory from Last Glacial Maximum (LGM) glaciation; and to identify a watershed size that is appropriate for systematic sampling. Mean denudation rates are 0.27 ± 0.14 mm/a for the Alpine foreland and 0.9 ± 0.3 mm/a for the crystalline Central Alps. The measured cosmogenic nuclide‐derived denudation rates are in good agreement with post‐LGM lake infill rates and are about twice as high as denudation rates from apatite fission track ages that record denudation from 9 to 5 Ma. In general, denudation rates are high in areas of high topography and high crustal thickness. The similarity in the spatial distribution and magnitude of denudation rates and those of rock uplift rates can be interpreted in several ways: (1) Postglacial rebound or climate change has introduced a transient change in which both uplift and denudation follow each other with a short lag time; (2) the amplitude of glacial to interglacial changes in both is small and is contained in the scatter of the data; (3) both are driven by ongoing convergence where their similarity might hint at some form of long‐term quasi steady state; or (4) enhanced continuous Quaternary erosion and isostatic compensation of the mass removed accounts for the distribution of present‐day rock uplift.
Characteristics of long‐duration precipitation events across the United States
Authors: Brommer David M. , Cerveny Randall S. , Balling Robert C.
Published: November 2007

Previous studies have indicated that extreme precipitation intensity is increasing over time, and has been attributed to anthropogenic warming. Generally these studies have limited analyses to data from daily rainfall totals. We extend those studies by examining characteristics associated with storms of varying duration. We find that significant differences exist in the character of long‐duration storms (those of twenty consecutive hours or more) from 1948 to 2004. Specifically we find that, although long‐duration storms are becoming wetter, (a) they are occurring less frequently and, consequently, comprising a progressively smaller proportion of the total storm number, and (b) they are contributing a smaller proportion of the total rainfall. Geographically, these storms are more likely to influence the Gulf States (particularly in autumn) and the central west coastal area of northern California. Fundamentally, this study suggests that evaluating precipitation over daily time frames may not capture the full complexities in extreme rainfall events.
Old iodine in fluids venting along the Central American convergent margin
Authors: Lu Zunli , Hensen Christian , Fehn Udo , Wallmann Klaus
Published: November 2007

Focused fluid expulsion at cold vents is a common feature of subduction zones, serving as an important backflux of water and volatile elements to the oceanic reservoir. The strong enrichment of iodine in fluids collected from mounds along the Central American convergent Margin allowed the determination of 129I/I ratios for age calculations in order to determine potential source formations in this active, erosional margin. The majority of the determined iodine ages are between 40 and 20 Ma. Because these ages are older than the age of host sediments and underthrust sediments on the oceanic plate (<18 Ma), a major contribution of iodine must come from old, organic rich sources in the upper plate. Both the iodine concentrations and ages determined for the mounds in this study are similar to reported values for hydrate fields at accretionary margins, indicating that iodine and associated organic carbon cycling at both erosional and accretionary margins may occur on similar time scales.
Inhomogeneous electromagnetic plane wave diffraction by a perfectly electric conducting wedge at oblique incidence
Authors: Kouyoumjian R. G. , Celandroni T. , Manara G. , Nepa P.
Published: November 2007

The diffraction of an inhomogeneous electromagnetic plane wave obliquely incident on the edge of a perfectly conducting wedge is analyzed, to extend the results for the normal incidence case reported by Kouyoumjian et al. (1996). Uniform high‐frequency expressions are obtained for the diffracted field in the format of the uniform geometrical theory of diffraction (UTD). The generalized dyadic diffraction coefficient in the standard UTD ray‐fixed coordinate system is represented by a 2 × 2 full matrix with the extra‐diagonal terms accounting for a coupling between the two components of the incident and diffracted electric field parallel and perpendicular to the edge‐fixed incidence and diffraction plane, respectively. The latter characteristic of the diffraction matrix is due to both the vectorial properties of the evanescent incident electric field and the inclusion of higher‐order terms in the asymptotic expression of the edge diffracted field. The introduction of higher‐order terms in the asymptotic evaluation also guarantees an improved accuracy for smaller values of the large parameter, namely, for observation points closer to the diffracting edge, as compared with the ordinary UTD.
Photodissociation spectroscopy of stored CH+ and CD+ ions: Analysis of theb 3Σ−-a 3Π system
Authors: Hechtfischer U. , Rostas J. , Lange M. , Linkemann J. , Schwalm D. , Wester R. , Wolf A. , Zajfman D.
Published: November 2007

We have measured the photodissociation spectrum of CH+ and CD+ molecular ions, stored as fast (MeV) ion beams in the heavy-ion storage ring TSR. Several bΣ−3-aΠ3 bands were observed as strong resonances because a large fraction of the ions in the metastable aΠ3(v=0) state were pumped to bΣ−3 levels and predissociated via the cΣ+3 state into C+ and H(D) fragments. From a rotational analysis of the 2-0, 3-0, and 4-0 bands in CH+ and the 3-0 and 4-0 bands in CD+, we derive spectroscopic constants for these levels and also revise a previous analysis of the 0-0 and 1-0 bands in CH+. Combining all data delivers new, significantly adjusted equilibrium constants for the bΣ−3 and aΠ3 electronic states. Apart from the spectroscopic analysis, we estimate the predissociation rates of the upper bΣ−3 vibrational levels in CH+ and compare them to a model. For the initial rovibrational distribution of the stored metastable CH+ molecules, the data indicate a faster vibrational cooling than derived before, and rotational cooling at a rate similar to the XΣ+1 ground state. New aspects of the spin-forbidden aΠ3-XΣ+1 radiative decay are discussed. Finally, we predict bΣ−3-aΠ3 absorption and aΠ3-XΣ+1 emission lines through which CH+ in the metastable aΠ3(v=0) state might be detectable in astrophysical environments.
Amplification of an ultrashort pulse laser by stimulated Raman scattering of a 1ns pulse in a low density plasma
Authors: Kirkwood R. K. , Dewald E. , Niemann C. , Meezan N. , Wilks S. C. , Price D. W. , Landen O. L. , Wurtele J. , Charman A. E. , Lindberg R. , Fisch N. J. , Malkin V. M. , Valeo E. O.
Published: November 2007

Experiments are described in which a 1mJ, 1ps, 1200nm seed laser beam is amplified by the interaction with an intersecting 350J, 1ns, 1054nm pump beam in a low density (1×1019∕cm3) plasma. The transmission of the seed beam is observed to be enhanced by ≳25× when the plasma is near the resonant density for stimulated Raman scattering, compared to measured transmissions at wavelengths just below the resonant value. The amplification is observed to increase rapidly with increases in both pump intensity and plasma density.
Single shot charge detection using a radio-frequency quantum point contact
Authors: Cassidy M. C. , Dzurak A. S. , Clark R. G. , Petersson K. D. , Farrer I. , Ritchie D. A. , Smith C. G.
Published: November 2007

We report on charge sensing measurements of a GaAs semiconductor quantum dot device using a radio frequency quantum point contact (rf-QPC). The rf-QPC is fully characterized at 4K and millikelvin temperatures and found to have a bandwidth exceeding 20MHz. For single shot charge sensing, we achieve a charge sensitivity of ∼2×10−4e∕Hz referred to the neighboring dot’s charge. The rf-QPC compares favorably with rf single electron transistor electrometers and promises to be an extremely useful tool for characterizing and measuring semiconductor quantum systems on fast time scales.
Magnetorotational instability in the Hall regime in a hot-electron plasma
Authors: Mikhailovskii A. B. , Lominadze J. G. , Galvão R. M. O. , Vladimirov S. V. , Churikov A. P. , Erokhin N. N. , Smolyakov A. I. , Tsypin V. S.
Published: November 2007

The magnetorotational instability (MRI) in the Hall regime in a hot-electron plasma is analyzed. The dispersion relation is derived for a rotating plasma with both finite electron pressure and pressure anisotropy. It is pointed out that the former effect has to be taken into account in the Hall regime, for β≳1, where β is the ratio of electron pressure to the magnetic field pressure. As a whole, the effects of order β weaken or suppress the MRI. It is shown that in the presence of electron pressure anisotropy, a hybrid of MRI and anisotropic instability appears, and that anisotropy of type T⊥>T∥ is destabilizing, while T∥>T⊥ is stabilizing, where T⊥ and T∥ are the perpendicular and parallel electron temperatures, respectively.
Engineering epitaxial γ-Al2O3 gate dielectric films on 4H-SiC
Authors: Tanner Carey M. , Toney Michael F. , Lu Jun , Blom Hans-Olof , Sawkar-Mathur Monica , Tafesse Melat A. , Chang Jane P.
Published: November 2007

The formation of epitaxial γ-Al2O3 thin films on 4H-SiC was found to be strongly dependent on the film thickness. An abrupt interface was observed in films up to 200 Å thick with an epitaxial relationship of γ-Al2O3(111)‖4H-SiC(0001) and γ-Al2O3(44¯0)‖4H-SiC(112¯0). The in-plane alignment between the film and the substrate is nearly complete for γ-Al2O3 films up to 115 Å thick, but quickly diminishes in thicker films. The films are found to be slightly strained laterally in tension; the strain increases with thickness and then decreases in films thicker than 200 Å, indicating strain relaxation which is accompanied by increased misorientation. By controlling the structure of ultrathin Al2O3 films, metal–oxide–semiconductor capacitors with Al2O3 gate dielectrics on 4H-SiC were found to have a very low leakage current density, suggesting suitability of Al2O3 for SiC device integration.
Plasma blobs in a basic toroidal experiment: Origin, dynamics, and induced transport
Authors: Müller S. H. , Diallo A. , Fasoli A. , Furno I. , Labit B. , Podestà M.
Published: November 2007

Detaching plasma blobs with very similar properties to tokamaks are observed in the basic toroidal plasma experiment TORPEX [A. Fasoli et al., Phys. Plasmas 13, 055902 (2006)]. The blobs originate from the breaking of wave crests of a drift-interchange wave, which span over regions characterized by strongly inhomogeneous background parameters. Once decoupled from the wave, the blobs follow a predominantly radial trajectory pattern. The blob-induced cross-field transport can instantaneously exceed the steady-state parallel fluxes by one order of magnitude, while accounting for only 10% of the time-average device losses. If the particles were confined in the parallel direction, as is the case in tokamaks, blobs would constitute the dominant loss mechanism in TORPEX. The presented results show that the presence of gradB is sufficient and neither a magnetic-topology change nor the presence of limiters, both absent in TORPEX, are necessary for the generation of blobs.
Formation processes of iron silicide nanoparticles studied by ex situ and in situ transmission electron microscopy
Authors: Won Jonghan , Kovács András , Naito Muneyuki , Ishimaru Manabu , Hirotsu Yoshihiko
Published: November 2007

The formation processes of iron silicide nanoparticles dependent on thermal annealing were examined by ex situ and in situ transmission electron microscopy (TEM). An Fe thin film with a thickness of ∼2 nm was deposited on a Si(100) substrate at room temperature using an electron-beam evaporation method, followed by thermal annealing at temperatures ranging from 573 to 1173 K. Ex situ TEM observations showed that pyramidal β-FeSi2 particles (1173 K) were formed via the ε-FeSi layer (573 K) and the γ-FeSi2 particle (873 K). Detailed observations by in situ TEM indicated that an amorphous Fe-Si layer was formed on the Si substrate in the as-deposited specimen. This amorphous layer was crystallized into ε-FeSi after thermal annealing and then hemispherical ε-FeSi particles together with metastable γ-FeSi2 were formed just beneath the surface of the Si substrate. With increasing annealing temperature, the ε phase changed to hemispherical γ-FeSi2 nanoparticles and finally the γ-FeSi2 particles transformed into pyramidal β-FeSi2 particles. We discuss the formation mechanism of the iron silicide nanoparticles at the atomic scale.
rf-microwave switches based on reversible semiconductor-metal transition of VO2 thin films synthesized by pulsed-laser deposition
Authors: Dumas-Bouchiat F. , Champeaux C. , Catherinot A. , Crunteanu A. , Blondy P.
Published: November 2007

Microwave switching devices based on the semiconductor-metal transition of VO2 thin films were developped on two types of substrates (C-plane sapphire and SiO2∕Si), and in both shunt and series configurations. Under thermal activation, the switches achieved up to 30–40dB average isolation of the radio-frequency (rf) signal on 500MHz–35GHz frequency band with weak insertion losses. These VO2-based switches can be electrically activated with commutation times less than 100ns, which make them promising candidates for realizing efficient and simple rf switches.
Formation and nonvolatile memory effect of nickel-oxygen-silicon nanoparticles
Authors: Chen Wei-Ren , Chang Ting-Chang , Yeh Jui-Lung , Sze Simon M. , Chang Chun-Yen , Chen Uei-Shin
Published: November 2007

This study reveals the formation of nickel-oxygen-silicon nanoparticles with nonvolatile memory effect by sputtering a commixed target in argon and oxygen ambiance. A transmission electron microscope clearly shows the embedded nanoparticles in the silicon oxide and the constituent was examined by x-ray photoelectron spectroscopy. The capacitor structure with embedded nickel-oxygen-silicon nanoparticles was also studied and it exhibited hysteresis characteristics after electrical operation. The memory window and retention of nickel-oxygen-silicon nanoparticles were enough to apply on nonvolatile memory. In addition, a physical mechanism was deduced to expound the role of oxygen in the formation of nickel-oxygen-silicon nanoparticles.
Surface-enhanced Raman spectroscopy and correlated scanning electron microscopy of individual carbon nanotubes
Authors: Kumar Rajay , Zhou Hao , Cronin Stephen B.
Published: November 2007

Raman spectra of individual carbon nanotubes are measured by scanning a focused laser spot (0.5μm diameter) over a large area (100μm2) before and after depositing silver nanoparticles. Local regions exhibiting surface enhanced Raman spectroscopy (SERS) were located with respect to a lithographically patterned grid, allowing subsequent scanning electron microscopy to be performed. The uniquely large aspect ratio of carbon nanotubes enables imaging of the nanoparticle geometry together with the SERS active molecule. By measuring the same individual carbon nanotube before and after metal nanoparticle deposition, the SERS enhancement factor is determined unambiguously. The data reveals SERS enhancement factors up to 134 000, a consistent upshift in the G band Raman frequency and nanoparticle heating in excess of 600°C.
The effect of coupling barrier thickness on structural and optical properties in asymmetrically coupled GaN/Al0.5Ga0.5N/GaN multiquantum wells
Authors: Park Young S. , Park Chang Mo , Hwang Bo Ra , Kang T. W. , Kim Yongmin , Im Hyunsik , Han Myung-Soo
Published: November 2007

The structural and optical properties of coupled, multiquantum-well structures, consisting of GaN(10 Å)/Al0.5Ga0.5N(12 or22 Å)/GaN(20 Å) bounded by Al0.5Ga0.5N (100 Å) barriers, were investigated by high resolution x-ray diffraction, transmission electron microscopy, and photoluminescence measurements. We studied the carrier dynamics in asymmetric double quantum wells by analyzing the temperature-dependent and time-resolved photoluminescence spectra. Carrier tunneling between the coupled quantum wells affected the optical properties. In our analysis of the effect of the carrier tunneling in terms of free-carrier screening, the effect was much weaker for the sample with Tib=12 Å than for that with Tib=22 Å.
Improved stability for piezoelectric crystals grown in the lead indium niobate–lead magnesium niobate–lead titanate system
Authors: Tian Jian , Han Pengdi , Huang Xinling , Pan Huixin , Carroll James F. , Payne David A.
Published: November 2007

Higher coercive fields (EC) and depoling temperatures (TR∕T) were obtained for crystals in the Pb(In1∕2Nb1∕2)O3–Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PIN–PMN–PT) ternary system. Data are given for a crystal boule with starting composition 0.24PIN-0.44PMN-0.32PT, and with chemical distributions along the growth direction. The dielectric, piezoelectric, and elastic properties were determined. Similar to binary PMN–PT, ternary PIN–PMN–PT crystals have outstanding piezoelectric properties (e.g., d33∼900–1900pm∕V, k33∼0.83–0.92). In addition, PIN stabilizes piezoelectric performance by doubling EC (∼6kV∕cm) and increasing TR∕T by ∼20°C. These improvements are advantageous for acoustic transducers used in high-drive applications.
Negative differential resistance at Ag∕Si nanowires on silicon carbide: From a passive to an active massively parallel architecture
Authors: Silly M. G. , Charra F. , Soukiassian P.
Published: November 2007

We study massively parallel Si atomic lines as a template for Ag deposition on silicon carbide surfaces by scanning tunneling microscopy and spectroscopy (electrons/photons). This atomically engineered passive system amazingly turns into an active network with Ag∕Si nanowires exhibiting a negative differential resistance behavior. This results from Ag atoms selectively inducing a surface state at Si nanowires yielding a double tunnel barrier. These findings lead to a massively parallel active architecture in the solid state.
Directed selection of a conformational antibody domain that prevents mature amyloid fibril formation by stabilizing Aβ protofibrils
Authors: Habicht Gernot , Haupt Christian , Friedrich Ralf P. , Hortschansky Peter , Sachse Carsten , Meinhardt Jessica , Wieligmann Karin , Gellermann Gerald P. , Brodhun Michael , Götz Jürgen , Halbhuber Karl-Jürgen , Röcken Christoph , Horn Uwe , Fändrich Marcus
Published: November 2007

The formation of amyloid fibrils is a common biochemical characteristic that occurs in Alzheimer's disease and several other amyloidoses. The unifying structural feature of amyloid fibrils is their specific type of β-sheet conformation that differentiates these fibrils from the products of normal protein folding reactions. Here we describe the generation of an antibody domain, termed B10, that recognizes an amyloid-specific and conformationally defined epitope. This antibody domain was selected by phage-display from a recombinant library of camelid antibody domains. Surface plasmon resonance, immunoblots, and immunohistochemistry show that this antibody domain distinguishes Aβ amyloid fibrils from disaggregated Aβ peptide as well as from specific Aβ oligomers. The antibody domain possesses functional activity in preventing the formation of mature amyloid fibrils by stabilizing Aβ protofibrils. These data suggest possible applications of B10 in the detection of amyloid fibrils or in the modulation of their formation.
Subnetwork analysis reveals dynamic features of complex (bio)chemical networks
Authors: Conradi Carsten , Flockerzi Dietrich , Raisch Jörg , Stelling Jörg
Published: November 2007

In analyzing and mathematical modeling of complex (bio)chemical reaction networks, formal methods that connect network structure and dynamic behavior are needed because often, quantitative knowledge of the networks is very limited. This applies to many important processes in cell biology. Chemical reaction network theory allows for the classification of the potential network behavior—for instance, with respect to the existence of multiple steady states—but is computationally limited to small systems. Here, we show that by analyzing subnetworks termed elementary flux modes, the applicability of the theory can be extended to more complex networks. For an example network inspired by cell cycle control in budding yeast, the approach allows for model discrimination, identification of key mechanisms for multistationarity, and robustness analysis. The presented methods will be helpful in modeling and analyzing other complex reaction networks.
DNA methylation, insulin resistance, and blood pressure in offspring determined by maternal periconceptional B vitamin and methionine status
Authors: Sinclair Kevin D. , Allegrucci Cinzia , Singh Ravinder , Gardner David S. , Sebastian Sonia , Bispham Jayson , Thurston Alexandra , Huntley John F. , Rees William D. , Maloney Christopher A. , Lea Richard G. , Craigon Jim , McEvoy Tom G. , Young Lorraine E.
Published: November 2007

A complex combination of adult health-related disorders can originate from developmental events that occurin utero. The periconceptional period may also be programmable. We report on the effects of restricting the supply of specific B vitamins (i.e., B12and folate) and methionine, within normal physiological ranges, from the periconceptional diet of mature female sheep. We hypothesized this would lead to epigenetic modifications to DNA methylation in the preovulatory oocyte and/or preimplantation embryo, with long-term health implications for offspring. DNA methylation is a key epigenetic contributor to maintenance of gene silencing that relies on a dietary supply of methyl groups. We observed no effects on pregnancy establishment or birth weight, but this modest early dietary intervention led to adult offspring that were both heavier and fatter, elicited altered immune responses to antigenic challenge, were insulin-resistant, and had elevated blood pressure–effects that were most obvious in males. The altered methylation status of 4% of 1,400 CpG islands examined by restriction landmark genome scanning in the fetal liver revealed compelling evidence of a widespread epigenetic mechanism associated with this nutritionally programmed effect. Intriguingly, more than half of the affected loci were specific to males. The data provide the first evidence that clinically relevant reductions in specific dietary inputs to the methionine/folate cycles during the periconceptional period can lead to widespread epigenetic alterations to DNA methylation in offspring, and modify adult health-related phenotypes.