bluuebunny/crossref_metadata_2025 huggingface dataset:
Haematoma after Coronary Angiography and Percutaneous Coronary Intervention via the Femoral Artery Frequency and Risk Factors
Authors: Andersen Kirsten , Bregendahl Marianne , Kaestel Helen , Skriver Mette , Ravkilde Jan
Published: May 2005

Background: The most common complication after coronary angiography (CA) and percutaneous coronary intervention (PCI) is the development of haematoma. Several changes in procedures regarding CA and PCI have been made in our department in recent years. The aim of this audit is to establish how many patients develop haematoma after CA/PCI via the femoral artery and subsequently to find predictors that increase the risk of developing haematoma.

Methods: We initially included 474 consecutive patients-322 patients undergoing CA and 141 patients undergoing PCI. Eleven patients were later excluded due to the absence of complete data. Thirty-three variables were registered in order to find predictors, which might increase the haematoma frequency. A univariate as well as a multivariate logistic regression analysis was performed.

Results: Of the 463 patients, 6 patients developed a haematoma > 10 cm (1.3%) and 41 patients developed a haematoma > 5 cm (8.9%). The following factors were found to be associated with the generation of haematoma: Women, systolic blood pressure > 160 mm Hg, artery puncture > 1, sheath time > 16 min, ACT ≥ 175 s, Glycoprotein (GP) IIB/IIIa inhibitors, Low Molecular Weight Heparin before procedure, personnel change during compression, and anti-coagulant-treatment before procedure.

Conclusions: The frequency of haematoma was 1.3% (> 10 cm) and 8.9% (> 5 cm), which corresponds with reports from similar studies and departments. The factors found to increase the risk of haematoma development can provide background for procedural changes and increase the focus on patients at increased risk in order to minimize the development of haematomas.
TELL and CALL in the Third Millenium: Pegagogical Approaches in a Growing EU-Community
Authors: HOLZMANN CHRISTIAN , KOLEFF INGE-ANNA , PETERS KLAUS
Published: May 2005

Contained within this special issue is a selection of papers presented at the 2004 annual EUROCALL
conference, hosted in early September in Vienna, Austria. CALL Austria, which is part of the great EUROCALL family, has played
a major role in disseminating pedagogical approaches towards TELL and CALL within Europe since the early 1980s. It has always been
a grass-roots movement, and its work has always reflected that fact that CALL Austria is run by active teachers, many of them teaching
at secondary level. Thus the application of new ideas in the language classroom was a major consideration in the preparation of
the 2004 Conference. In this context welcoming Eurocallers to Vienna in 2004 has been a crowning achievement and a reward for our
attempts to promote the meaningful use of computer technologies in language
learning. “TELL and CALL in the Third Millenium: Pegagogical Approaches
in a Growing EU-Community”, focussed on the great variety of concepts, applications and best-practice models
concerning pedagogy and methodology supported by technological developments, particularly in relation to language learning and
teaching. As in previous conferences sub-themes focussed on the changes in practices involving literacy brought about by the
World Wide Web; the need to re-interpret current teaching paradigms; the relationship
between the more ‘traditional’ language skills and the ‘new
literacies’; interactivity, learner interaction and feedback; and spoken and written corpora in language
teaching and learning.
CALL from the margins: effective dissemination of CALL research and good practices
Authors: COLEMAN JAMES A.
Published: May 2005

The symbolic location of EUROCALL's 2004 conference in Vienna offered to both new members from Eastern
Europe and established members from the West an opportunity to review the relationship between computer assisted language learning
(CALL) and language teaching in general. CALL is defined as an ‘academic field that explores the role of information and
communication technologies in language learning and teaching’ (EUROCALL 1999; for a discussion of CALL as an interdisciplinary
research domain, see Levy, 1997). CALL practitioners and researchers have long been aware of the importance of recognition within the
broader discipline of language learning and teaching, as the joint EUROCALL/CALICO/IALL Research Policy Statement (EUROCALL 1999)
explicitly noted. Yet CALL in fact remains marginalised in several ways which this article will explore. In seeking to promote more
effective dissemination of good teaching practices and especially of research in CALL, the article will evoke the UKÕs predominant
role in introducing Quality Assurance (QA) to higher education teaching and
research – a trend which the Bologna Process will surely intensify throughout Europe. The author will draw on his current
role as language research coordinator at the UK's Open University, and on substantial experience as a QA insider in both
teaching and research, to analyse successes and failures in dissemination of both research and good teaching/learning practices.
He will propose strategies for moving CALL from the margins towards the centre of language learning. In so doing, he will also provide
an incidental overview of some key journals and conferences in the domain.
E-learning pedagogy in the third millennium: the need for combining social and cognitive constructivist approaches
Authors: FELIX USCHI
Published: May 2005

An analysis of the characteristics of education and educational institutions of the third millennium shows that
predominant features are flexibility, inclusiveness, collaboration, authenticity, relevance and extended institutional boundaries.
Roles of both students and teachers have changed significantly as educational goals have broadened to include lifelong learning,
global interaction, the acquisition of meta-cognitive knowledge and skills, and processes include negotiated curricula and real-life
tutors and informants. This is a demanding package that appears to lead us naturally to a social constructivist paradigm for
learning and teaching. While few would dispute the value of this approach in
humanistic terms, a series of dilemmas – social, conceptual, political,
pedagogical – have been articulated. The author will demonstrate that although these are not insurmountable, addressing
them has major time implications. The paper argues that to free up time we need to combine social constructivist activities
with cognitive constructivist ones, incorporating personalised ICALL systems.
A hybrid approach to developing CALL materials: authoring with Macromedia’s Dreamweaver/Coursebuilder
Authors: ROGERSON-REVELL PAMELA
Published: May 2005

This paper describes some of the pedagogical and technical issues involved in adopting a hybrid approach to CALL
materials development. It illustrates some of these issues with reference to a vocational CALL project, LANCAM, which took such a
hybrid approach. It describes some of the benefits and considerations involved in hybrid development and evaluates the commercial web
development tool, ‘Dreamweaver’ and its extension application
‘Coursebuilder’, which was used to author the LANCAM materials. It argues for a reconsideration of generic web development
tools in CALL authoring and also for language experts to be actively involved in the instructional design process.
Offshore breaking of impact tsunami: The Van Dorn effect revisited
Authors: Korycansky D. G. , Lynett P. J.
Published: May 2005

We report on calculations of the shoaling and off‐shore breaking of typical wavetrains from sub‐km impactors into the deep ocean. We use the COULWAVE code to compute the propagation of waves through simple bathymetry profiles typical of the North American Pacific coast and the Gulf of Mexico. Numerical results are consistent with those predicted by nonlinear shoaling theory. Our primary result is that large long‐period waves of the type considered should indeed break far offshore, as suggested by W. G. Van Dorn for similar waves generated by underwater explosions. Typical breaking distances range from ≈3–17 km for the Pacific coast, and up to ∼200 km for the Gulf coast. The inclusion of bottom friction affects the results; for very gentle slopes like the Gulf coast, a modest amount of bottom friction supplies enough dissipation to suppress wave breaking.
Terminal settling velocity measurements of volcanic ash during the 2002–2003 Etna eruption by an X‐band microwave rain gauge disdrometer
Authors: Scollo Simona , Coltelli Mauro , Prodi Franco , Folegani Marco , Natali Stefano
Published: May 2005

This is the first report in the scientific literature of direct measurement of the terminal settling velocity of volcanic particles during an eruption. Field measurements using a continuous wave X‐band disdrometer were carried out at Mt. Etna on 18 and 19 December 2002, when the explosive activity produced a 4 km high volcanic plume. These data allow the estimation of the intensity of the fallout and the measurement of the terminal settling velocities of the volcanic particles in real‐time. The main results are: (1) the tested instrument detected coherent falling volcanic particles from 0.2 to 1 mm diameter; (2) measured terminal settling velocities were in agreement with both experimental and theoretical methods; (3) however, the measured velocities were clustered around few discrete values, rather than a range of velocities as would be expected if the particles were falling simultaneously and discretely. This new methodology has many new applications for local hazard mitigation and improved understanding of fallout processes.
Large‐scale variabilities of wintertime wind stress curl field in the North Pacific and their relation to atmospheric teleconnection patterns
Authors: Ishi Yuko , Hanawa Kimio
Published: May 2005

Wintertime wind stress curl (WSC) field in the North Pacific is investigated to reveal large‐scale variabilities and their relation to atmospheric teleconnection patterns. It is found that the leading empirical orthogonal function (EOF) and the next three rotated‐EOF modes of wintertime WSC anomalies well correspond to those of atmospheric teleconnection patterns, i.e., Pacific/North American (PNA), Western Pacific (WP), Tropical/Northern Hemisphere (TNH), and Eastern Pacific (EP) teleconnection patterns, respectively. Time coefficient of the first EOF mode well correlates with the North Pacific Index, and does with the Pacific Decadal Oscillation Index, to some degree. It is also found that Sverdrup transports in the two zonal bands of 25°N–30°N and 42.5°N–47.5°N have highly negative correlation and these variations can be represented by the forcing field of the first EOF mode: the PNA forcing makes both subtropical and subpolar gyres spin‐up/spin‐down simultaneously.
Sublithospheric small‐scale convection and its implications for the residual topography at old ocean basins and the plate model
Authors: Huang Jinshui , Zhong Shijie
Published: May 2005

The seafloor topography and heat flux differ significantly from the predictions of the half‐space cooling (HSC) model at old ocean basins. Understanding the deviations has important implications for thermal evolution of oceanic lithosphere and large‐scale mantle dynamics. A widely used model that explains significant fraction of the deviations is the plate model, but the dynamical feasibility of the plate model has never been demonstrated. In this study, we investigated the effects of sublithospheric small‐scale convection (SSC) and of internal heating on seafloor heat flux and topography and mantle thermal structure, and we examined the dynamic feasibility of the plate model by formulating high‐ resolution two‐dimensional numerical models of mantle convection with strongly temperature‐ and depth‐dependent rheology. We found that mantle convection with tectonic plates often leads to formation of a broad thermal anomaly below old lithosphere where the mantle is not cooled by subducted slabs and heat transfer is less efficient because of thick lithosphere, especially when significant internal heating is present. This trapped heat may exist in the middle mantle when the SSC is absent, and it may also be redistributed by the SSC to shallow depths to reheat the lithosphere and to homogenize mantle temperature. When internal heating accounts for >∼60% of the total heat output, the trapped heat may provide sufficient heat supply to preferentially reheat old lithosphere via SSC while maintaining uniform mantle temperature. We suggest that the trapped heat and the SSC are responsible for the residual heat flux and topography at old ocean basins relative to the HSC model predictions. Our models also show that for the plate model to be dynamically viable, both the SSC and significant internal heating (>60%) are necessary. This is because only the SSC in a mantle with significant internal heating can erode and reheat the lithosphere while maintaining a nearly constant mantle temperature below lithosphere, which is the basic assumption of the plate model. With the viscosity structure and internal heating rate for the present‐day mantle, we think that the plate model is dynamically viable.
Vertical distribution of cloud condensation nuclei concentrations and their effect on microphysical properties of clouds over the sea near the southwest islands of Japan
Authors: Adhikari M. , Ishizaka Y. , Minda H. , Kazaoka R. , Jensen J. B. , Gras J. L. , Nakajima T.
Published: May 2005

Aircraft observations were performed over the sea near the southwest islands of Japan under Asian Atmospheric Particulate Environmental Change Experiment 2/Asian Pacific Regional Aerosol Characterization Experiment (APEX‐E2/ACE‐Asia) project during the period of 16–28 April 2001. The polluted air mass from east Asia was associated with very high concentrations of SO2 (1–10 ppb) and aerosol particles (3000–5000 cm−3) in the marine boundary layer. The cloud condensation nuclei (CCN) concentration at 0.3% supersaturation was as high as 800–2000 cm−3 during the penetrations of air pollutants from east Asia. The correlation coefficient between SO2 and aerosol particles was significant in such polluted atmosphere. Concentration of CCN (NCCN) was linearly related to concentration of aerosol particles (NAP) according to NCCN ∼ 0.75NAP. The ratio of CCN to aerosol condensation nuclei particle concentrations was lower than 0.3 in the relatively clean maritime atmosphere, but it was as high as ∼0.5 in the continentally influenced atmosphere in the boundary layer. These results indicated that the influence of anthropogenic pollutants from east Asia increased the contribution percentage of aerosol particles to CCN in the polluted atmosphere over the observation area. The observational results also indicated that a mean cloud droplet concentration (NC) in the continentally influenced clouds was ∼2 times as much as NC in the relatively clean maritime clouds. The slope of log‐log relationship between NC and NCCN was ∼0.39. This study strongly suggests that high CCN concentration formed many cloud droplets and decreased their effective radius at similar liquid water content under the outflow of air pollutants from east Asia.
Reactive uptake of glyoxal by particulate matter
Authors: Liggio John , Li Shao‐Meng , McLaren Robert
Published: May 2005

The uptake of gaseous glyoxal onto particulate matter has been studied in laboratory experiments under conditions relevant to the ambient atmosphere using an aerosol mass spectrometer. The growth rates and reactive uptake coefficients, γ, were derived by fitting a model of particle growth to the experimental data. Organic growth rates varied from 1.05 × 10−11 to 23.1 × 10−11 μg particle−1 min−1 in the presence of ∼5 ppb glyoxal. Uptake coefficients (γ) of glyoxal varied from 8.0 × 10−4 to 7.3 × 10−3 with a median γ = 2.9 × 10−3, observed for (NH4)2SO4 seed aerosols at 55% relative humidity. Increased γ values were related to increased particle acidity, indicating that acid catalysis played a role in the heterogeneous mechanism. Experiments conducted at very low relative humidity, with the potential to be highly acidic, resulted in very low reactive uptake. These uptake coefficients indicated that the heterogeneous loss of glyoxal in the atmosphere is at least as important as gas phase loss mechanisms, including photolysis and reaction with hydroxyl radicals. Glyoxal lifetime due to heterogeneous reactions under typical ambient conditions was estimated to be τhet = 5–287 min. In rural and remote areas the glyoxal uptake can lead to 5–257 ng m−3 of secondary organic aerosols in 8 hours, consistent with recent ambient measurements.
Effect of the onset of southwest monsoon on the atmospheric electric conductivity over the Arabian Sea
Authors: Pawar S. D. , Siingh Devendraa , Gopalakrishnan V. , Kamra A. K.
Published: May 2005

Measurements of the atmospheric electric conductivity and small, intermediate, and large ion concentrations made at four locations over the Arabian Sea onboard ORV Sagarkanya in the premonsoon and monsoon seasons during the Arabian Sea Monsoon Experiment in 2002–2003 are reported. Observations show a threefold increase in the daily average value of conductivity over a period of ∼10 days preceding the onset of southwest monsoon. The enhanced values of conductivity are accompanied with a higher concentration of large ions. Although ion concentrations in all categories exhibit large fluctuations, the average concentration levels of small ions decrease and of large ions increase during the monsoon period. It is proposed that the enhancement in conductivity associated with the onset of monsoon is due to the highly charged large ions produced by the bubble bursting process at the air‐sea interface caused by the breaking waves during the high‐wind‐speed periods over the Arabian Sea. The correlation coefficient between the large ion concentration and wind speed measured at Sagarkanya is found to increase from 0.41, 0.16, and 0.23 in the premonsoon and two monsoon periods to 0.56 during the monsoon onset period. The enhanced value and the large variability of large ion concentrations observed during the monsoon season are associated with the spatial and temporal heterogeneity in not only their production but also their dissipation by the cloud scavenging processes over the Arabian Sea.
Radiation from a monopole antenna in front of a conducting cylinder
Authors: Wang Quanxin , Shen Zhongxiang , Lu Yilong
Published: May 2005

A monopole antenna in front of a conducting cylinder is analyzed by the modal‐expansion method and scattering matrix method. An infinite perfectly conducting plate is introduced at the top of the monopole antenna to facilitate the modal‐expansion analysis. Scattered fields due to the reflecting cylinder are obtained by the scattering matrix method with the aid of cylindrical function's addition theorem. Enforcement of continuity conditions of the tangential field components across the regional surfaces results in the matrix equation for determining the expansion coefficients. Numerical results for the return loss and radiation pattern of a monopole antenna in front of a conducting cylinder are presented and are in good agreement with experimental ones. The effect of the cylindrical reflector's radius and its distance from the monopole on the antenna's radiation performance is also examined.
Zone of influence of a gas permeable membrane system for delivery of gases to groundwater
Authors: Agarwal Navin , Semmens Michael J. , Novak Paige J. , Hozalski Raymond M.
Published: May 2005

One approach for cleaning up aquifers contaminated with organic chemicals is to stimulate biological degradation in situ by addition of gases such as oxygen or hydrogen, which can be introduced into the groundwater using novel hollow‐fiber membrane gas transfer systems. In this research, pilot‐scale experiments were performed using a 1 m × 2 m × 1 m model sand aquifer to evaluate the effects of membrane system design and operation on the zone of influence of the dissolved gas plume about a vertical narrow bore (2.54 cm inner diameter) well installed in the aquifer. Two membrane systems were evaluated: (1) a membrane module installed directly in the narrow bore slotted well (“in‐well” design) which was operated passively and with addition of water pumped from a downgradient extraction well and (2) an “external” module located above the ground surface which was operated in pumped mode only. In addition to the physical experiments a two‐dimensional MODFLOW‐MT3D simulation model was created using commercial software, calibrated and verified using the experimental data, then used to evaluate additional operational strategies not investigated experimentally. The simulated zones of influence from the calibrated MODFLOW‐MT3D model were in good agreement (−1.3 to 14.4%) with experimental observations. Simulations of various well configurations (i.e., locations of extraction and injection wells), pumping rates, and dissolved gas consumption rates suggested that these factors can have a significant effect on the zone of influence and hence the cost of installation and operation of a membrane gas transfer system.
Serum Ferritin in Stroke: A Marker of Increased Body Iron Stores or Stroke Severity?
Authors: Millerot Emilie , Prigent-Tessier Anne S , Bertrand Nathalie M , Faure Philippe J-C , Mossiat Claude M , Giroud Maurice E , Beley Alain G , Marie Christine
Published: May 2005

To evaluate the effect of body iron stores on the vulnerability of the brain to ischemia, a focal permanent brain ischemia was induced by photothrombotic occlusion of cortical vessels in rats with or without chronic treatment with iron dextran (25 mg iron/kg, every other day for 20 days, intraperitoneally). Iron dextran induced systemic iron overload as evidenced by high ferritin (Ft) (x 5) and total iron levels (x 3) in serum as well as increased Ft expression in the liver and heart. Conversely, neither serum free iron levels nor Ft expression in the brain were changed by iron dextran. Finally, infarct volume was not modified by iron dextran. In addition, induction of ischemia in rats treated with FeCl3 (560 μg iron/kg, intravenously) as a means of increasing serum free iron levels during the ischemic period did not enlarge infarct volume. We then explored the effect of brain ischemia itself on serum Ft by measuring serum Ft before and after induction of brain ischemic insults with different neurologic outcomes in rats (brain embolization with microspheres, photothrombotic occlusion of cortical vessels, four-vessel occlusion). Serum Ft levels were found higher at day 1 after ischemia than before ischemia only in rats subjected to the most severe insult (brain embolization). In conclusion, our study showed that increased body iron stores do not increase the vulnerability of the brain to ischemia and that brain ischemia, if severe, results in the elevation of serum Ft levels.
Heat Acclimation Increases Hypoxia-Inducible Factor 1α and Erythropoietin Receptor Expression: Implication for Neuroprotection after Closed Head Injury in Mice
Authors: Shein Na'ama A , Horowitz Michal , Alexandrovich Alexander G , Tsenter Jeanna , Shohami Esther
Published: May 2005

Experimental evidence indicates that long-term exposure to moderately high ambient temperature (heat acclimation, HA) mediates cross-tolerance to various types of subsequently applied stress. The transcriptional activator hypoxia-inducible factor 1 (HIF-1) has been implicated in playing a critical role in HA. It also regulates the expression of Erythropoietin (Epo), whose neuroprotective effects have been shown in a variety of brain injuries. The aim of the present study was to examine whether HA exerts a beneficial effect on the outcome of closed head injury (CHI) in mice and to explore the possible involvement of HIF-1 and Epo in this process. Heat acclimated mice and matched normothermic controls were subjected to CHI or sham surgery. Postinjury motor and cognitive parameters of acclimated mice were compared with those of controls. Mice were killed at various time points after injury or sham surgery and brain levels of HIF-1α, the inducible subunit of HIF-1, Epo, and the specific erythropoietin receptor (EpoR) were analyzed by Western immunoblotting. Motor and cognitive functions of acclimated mice were significantly better than those of controls. Heat acclimation was found to induce a significant increase in expression of nuclear HIF-1α and EpoR. The EpoR/Epo ratio was also significantly higher in acclimated mice as compared with controls. Nuclear HIF-1α and EpoR were higher in the acclimated group at 4 h after injury as well. The improved outcome of acclimated mice taken together with the basal and postinjury upregulation of the examined proteins suggests the involvement of this pathway in HA-induced neuroprotection.
Effect of Targeted Deletion of the Heme Oxygenase-2 Gene on Hemoglobin Toxicity in the Striatum
Authors: Qu Yan , Chen Jing , Benvenisti-Zarom Luna , Ma Xin , Regan Raymond F
Published: May 2005

The heme oxygenase (HO) enzymes catalyze the rate-limiting step in the breakdown of heme to iron, carbon monoxide, and biliverdin. A prior cell culture study demonstrated that deletion of HO-2, the isoform constitutively expressed in neurons, attenuated hemoglobin (Hb) neurotoxicity. The present study tested the hypothesis that HO-2 gene deletion is cytoprotective in a model of Hb toxicity in vivo. Stereotactic injection of 6 μL stroma-free Hb (SFHb) into the striatum significantly increased protein oxidation in wild-type mice at 24 to 72 h, as detected by an assay for carbonyl groups. At 72 h, carbonylation was increased 2.5-fold compared with that in the contralateral striatum. In HO-2 knockout mice, protein oxidation was not increased at 24 h, and was increased by only 1.7-fold at 72 h. Similarly, striatal lipid peroxidation, as detected by the malondialdehyde assay, was significantly greater in the SFHb-injected striata of wild-type mice than in knockout mice. Striatal cell viability, determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, was 45.0%±6.3% of that in contralateral striata in wild-type mice at 72 h; it was increased to 85%±8% in knockouts. Heme oxygenase-2 gene deletion did not alter weight loss or mortality after SFHb injection. Baseline striatal HO-1 expression was similar in knockout and wild-type mice; induction after SFHb injection occurred more rapidly in the latter. These results suggest that HO-2 gene deletion protects striatal cells from the oxidative toxicity of Hb in vivo. Pharmacologic or genetic strategies that target HO-2 may be beneficial after central nervous system hemorrhage, and warrant further investigation.
VEGF-Induced BBB Permeability is Associated with an MMP-9 Activity Increase in Cerebral ischemia: Both Effects Decreased by ANG-1
Authors: Valable Samuel , Montaner Joan , Bellail Anita , Berezowski Vincent , Brillault Julien , Cecchelli Romeo , Divoux Didier , MacKenzie Eric T , Bernaudin Myriam , Roussel Simon , Petit Edwige
Published: May 2005

After cerebral ischemia, angiogenesis, by supplying for the deficient perfusion, may be a beneficial process for limiting neuronal death and promoting tissue repair. In this study, we showed that the combination of Ang-1 and vascular endothelial growth factor (VEGF) provides a more adapted therapeutic strategy than the use of VEGF alone. Indeed, we showed on a focal ischemia model that an early administration of VEGF exacerbates ischemic damage, because of its effects on blood—brain barrier (BBB) permeability. In contrast, a coapplication of Ang-1 and VEGF leads to a significant reduction of the ischemic and edema volumes by 50% and 42%, respectively, in comparison with VEGF-treated mice. We proposed that Ang-1 blocks the BBB permeability effect of VEGF in association with a modulation of matrix metalloproteinase (MMP) activity. Indeed, we showed on both ischemic in vivo and BBB in vitro models that VEGF enhances BBB damage and MMP-9 activity and that Ang-1 counteracts both effects. However, we also showed a synergic angiogenic effect of Ang-1 and VEGF in the brain. Taken together, these results allow to propose that, in cerebral ischemia, the combination of Ang-1 and VEGF could be used early to promote the formation of mature neovessels without inducing side effects on BBB permeability.
Density-matrix renormalization-group algorithms with nonorthogonal orbitals and non-Hermitian operators, and applications to polyenes
Authors: Chan Garnet Kin-Lic , Van Voorhis Troy
Published: May 2005

We describe the theory and implementation of two extensions to the density-matrix renormalization-group (DMRG) algorithm in quantum chemistry: (i) to work with an underlying nonorthogonal one-particle basis (using a biorthogonal formulation) and (ii) to use non-Hermitian and complex operators and complex wave functions, which occur naturally in biorthogonal formulations. Using these developments, we carry out ground-state calculations on ethene, butadiene, and hexatriene, in a polarized atomic-orbital basis. The description of correlation in these systems using a localized nonorthogonal basis is improved over molecular-orbital DMRG calculations, and comparable to or better than coupled-cluster calculations, although we encountered numerical problems associated with non-Hermiticity. We believe that the non-Hermitian DMRG algorithm may further become useful in conjunction with other non-Hermitian Hamiltonians, for example, similarity-transformed coupled-cluster Hamiltonians.
Projection of two-dimensional diffusion in a narrow channel onto the longitudinal dimension
Authors: Kalinay P. , Percus J. K.
Published: May 2005

Diffusion in a narrow two-dimensional channel of width A(x), depending on the longitudinal coordinate x, is the object of our study. We show how the 2+1 dimensional diffusion equation can be projected onto a 1+1 dimensional one, governing corresponding one-dimensional density, in a steady-state approximation. Then we demonstrate the method on a nontrivial exactly solvable case for A(x)=x and discuss projection of the initial condition.
Theoretical study on germanium cyanide radical GeCN and its ions
Authors: Wang Qiang , Ding Yi-hong , Sun Chia-chung
Published: May 2005

A detailed theoretical study is performed on the hitherto unknown germanium cyanide radical and its ions. The Π2 state GeCN lies 5.0 kcal/mol lower than the Π2 state GeNC at the coupled-cluster theory including single and double excitations and perturbative inclusion of triple excitations [CCSD(T)]/6-311++G(3df)//quadratic configuration interaction with single and double excitations (QCISD)/6-311G(d)+zero-point vibrational energy (ZPVE) level. For interconversion between them, two electronic state pathways A′2 and A″2 are located, with the latter being 0.7 kcal/mol more favorable than the former. On the A″2 path, the GeCN→GeNC and GeNC→GeCN conversion barriers are 14.5 and 9.5 kcal/mol, respectively. The detailed singlet and triplet potential-energy surfaces of both the cationic and anionic GeCN species are also investigated. On the ground-state electronic hypersurface, singlet GeNC+ is 4.6 kcal/mol more stable than singlet GeCN+, whereas triplet GeNC− is 10.0 kcal/mol less stable than triplet GeCN−. The relative energy difference between the GeCN0,± and GeNC0,± can be well correlated with the number of vacant orbitals on the Ge atom. The stability of the neutral and ionic CGeN and cyclic cGeCN is also discussed. The predicted structures, spectroscopies, ionization, and affinity energies as well as the Renner–Teller properties are expected to provide reliable estimates for future characterization of the potential GeCN and GeNC radicals as well as their ionic counterparts both in the laboratory and in the interstellar space.
The wetting-dewetting transition of monolayer water on a hydrophobic metal surface observed by surface-state resonant second-harmonic generation
Authors: Dounce Susan M. , Jen Shih-Hui , Yang Minchul , Dai Hai-Lung
Published: May 2005

The isothermal adsorption and desorption of monolayer water on a Ag(110) surface in the temperature range of 130–137 K were characterized by monitoring second-harmonic (SH) generation from the silver surface. The SH intensity resonantly enhanced by the silver surface-state transition is highly sensitive to the amount of silver surface area covered by water and allows the observation of an abrupt change in the adsorption/desorption behavior at 133.5 K. At temperatures below 133.5 K water wets the Ag surface in a two-dimensional structure with a measured desorption energy of 25.0 (±3.3)kJ∕mol. At temperatures greater than 133.5 K water desorbs from three-dimensional clusters with a measured desorption energy of 48.3 (±2.2)kJ∕mol, in agreement with temperature-programmed desorption measurements. This wetting-dewetting transition of water adsorbed on the silver surface at 133.5 K is supported by classical nucleation theory calculations.
Mechanism for singular behavior in vibrational spectra of topologically disordered systems: Short-range attractions
Authors: Wu Ten-Ming , Chang S. L. , Tsai K. H.
Published: May 2005

At low-enough fluid densities, we have found some naive singular behavior, like the van Hove singularities in the phonon spectra of lattices, appearing in the instantaneous normal mode spectra of the Lennard-Jones (LJ) 2n-n fluids, which serve as a prototype of topologically disordered systems. The singular behavior cannot be predicted by the mean-field theory, but interpreted by the perturbed binary modes of some special pairs, called the mutual nearest neighbor pairs, at separations corresponding to the extreme binary frequencies, which are solely determined by the attractive part of the LJ 2n-n pair potential. By reducing the range of attraction in the pair potential under the conditions of the same particle diameter and well depth, the tendency for the appearance of the singular behavior shifts to higher fluid densities. From this study, we conclude that pair potential with a short-range attraction can be a mechanism to produce a counterpart of the van Hove singularity in the vibrational spectra of disordered systems without a reference lattice.
Calculation of accurate permanent dipole moments of the lowest Σ+1,3 states of heteronuclear alkali dimers using extended basis sets
Authors: Aymar M. , Dulieu O.
Published: May 2005

Obtaining ultracold samples of dipolar molecules is a current challenge which requires an accurate knowledge of their electronic properties to guide the ongoing experiments. In this paper, we systematically investigate the ground state and the lowest triplet state of mixed alkali dimers (involving Li, Na, K, Rb, Cs) using a standard quantum chemistry approach based on pseudopotentials for atomic core representation, Gaussian basis sets, and effective terms for core polarization effects. We emphasize on the convergence of the results for permanent dipole moments regarding the size of the Gaussian basis set, and we discuss their predicted accuracy by comparing to other theoretical calculations or available experimental values. We also revisit the difficulty to compare computed potential curves among published papers, due to the differences in the modelization of core-core interaction.
Combinatorial and high-throughput measurements of the modulus of thin polymer films
Authors: Stafford Christopher M. , Guo Shu , Harrison Christopher , Chiang Martin Y. M.
Published: May 2005

We describe the design and refinement of a high-throughput buckling-based metrology for ascertaining the mechanical properties (e.g., modulus) of combinatorial thin polymer film libraries. We provide critical details for the construction of a suitable strain stage, describe sample preparation, and highlight methods for high-throughput data acquisition and data analysis. To illustrate the combinatorial and high-throughput capability of this metrology, we prepare and evaluate films possessing a gradient in the elastic modulus and compare the results with an analytical expression derived from composite beam theory. Application of this metrology is very simple and practically any laboratory, academic or industrial, can perform such measurements with only modest investment in equipment. Although developed as a platform for investigating combinatorial libraries, researchers can take advantage of the high-throughput nature of this metrology to measure noncombinatorial film specimens as well.
Library design using genetic algorithms for catalyst discovery and optimization
Authors: Clerc Frederic , Lengliz Mourad , Farrusseng David , Mirodatos Claude , Pereira Sílvia R. M. , Rakotomalala Ricco
Published: May 2005

This study reports a detailed investigation of catalyst library design by genetic algorithm (GA). A methodology for assessing GA configurations is described. Operators, which promote the optimization speed while being robust to noise and outliers, are revealed through statistical studies. The genetic algorithms were implemented in GA platform software called OptiCat, which enables the construction of custom-made workflows using a tool box of operators. Two separate studies were carried out (i) on a virtual benchmark and (ii) on real surface response which is derived from HT screening. Additionally, we report a methodology to model a complex surface response by binning the search space in small zones that are then independently modeled by linear regression. In contrast to artificial neural networks, this approach allows one to obtain an explicit model in an analogical form that can be further used in Excel or entered in OptiCat to perform simulations. While speeding the implementation of a hybrid algorithm combining a GA with a knowledge-based extraction engine is described, while speeding up the optimization process by means of virtual prescreening the hybrid GA enables one to open the “black-box” by providing knowledge as a set of association rules.
Evaluation of temperature-dependent adhesive performance via combinatorial probe tack measurements
Authors: Moon Seung-ho , Chiche Arnaud , Forster Aaron M. , Zhang Wenhua , Stafford Christopher M.
Published: May 2005

We describe the design and application of a temperature gradient probe tack apparatus for investigating the adhesive performance of model pressure-sensitive adhesives (PSAs). In particular, we illustrate a probe tack apparatus for studying the effect of temperature on three critical adhesion identifiers: adhesion energy, elongation at break, and debonding mechanisms. The measurement temperature is varied across the PSA film using a gradient temperature stage constructed from a transparent sapphire plate with a heating and cooling source positioned at opposite ends. The transparent substrate allows visualization of the contact area and debonding mechanisms during the test. The gradient temperature stage is integrated onto a motorized x-y stage, enabling a matrix of probe tack tests to be conducted across the PSA film at different sample temperatures. We use a spherical probe to evaluate the adhesive performance of a 150μm thick model poly(styrene-b-isoprene-b-styrene) PSA film between a temperature range of 10 °C to 100 °C. We demonstrate that this apparatus is a viable combinatorial design for tack measurements and may be extended to more complicated two-dimensional gradient films.
Integration of MALDI-TOFMS as high-throughput screening tool into the workflow of combinatorial polymer research
Authors: Meier Michael A. R. , Schubert Ulrich S.
Published: May 2005

The possibilities of an integration of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) as an high-throughput screening tool into the workflow of combinatorial materials research are discussed. A multiple layer sample preparation technique for MALDI is described in detail and its possibilities of automation and miniaturization are discussed. Automated MALDI sample preparation could be performed within an automated synthesizer robot as well as with an ink-jet printer. The first approach offers the possibility of online reaction monitoring, whereas the second approach gives the opportunity of applications in ultra-high-throughput environments. Moreover, an example of high-throughput screening of a polymerization reaction by MALDI-TOFMS is discussed.
Lagrangian formalism for nonlinear second-order Riccati systems: One-dimensional integrability and two-dimensional superintegrability
Authors: Cariñena José F. , Rañada Manuel F. , Santander Mariano
Published: May 2005

The existence of a Lagrangian description for the second-order Riccati equation is analyzed and the results are applied to the study of two different nonlinear systems both related with the generalized Riccati equation. The Lagrangians are non-natural and the forces are not derivable from a potential. The constant value E of a preserved energy function can be used as an appropriate parameter for characterizing the behavior of the solutions of these two systems. In the second part the existence of two-dimensional versions endowed with superintegrability is proved. The explicit expressions of the additional integrals are obtained in both cases. Finally it is proved that the orbits of the second system, that represents a nonlinear oscillator, can be considered as nonlinear Lissajous figures
Resistively heated high temperature atomic beam source
Authors: Ahmed N. , Nadeem Ali , Nawaz M. , Bhatti S. A. , Iqbal M. , Baig M. A.
Published: May 2005

We present the design and fabrication of a resistively heated high temperature atomic beam source for spectroscopic studies of refractory metals. The beam source consists of cylindrical shape crucible made of tantalum enclosed by a 0.05mm thick tantalum foil to heat the crucible by radiation. The atomic beam sources can be operated continuously for several hours under stable conditions for up to 2300°C. The design is simple and versatile and atomic beams of any element can be generated. This source has been used to study the Rydberg states of elements requiring high temperature such as uranium, tin, etc.
Scanning low-temperature element-specific magnetic microscopy
Authors: Cady A. , Haskel D. , Lang J. C. , Srajer G. , Chupas P. , Osborn R. , Mitchell J. F. , Ahn J. S. , Hur N. , Park S. , Cheong S.-W.
Published: May 2005

We have developed a low-temperature element-specific magnetic microscopy instrument at beamline 4-ID-D of the Advanced Photon Source. The setup enables simultaneous chemical and magnetic characterization of materials with ∼1μm2 resolution at low temperature (>10K) under a moderate applied field (<0.8T). We demonstrate the potential of this apparatus by presenting results correlating chemical and magnetic local behavior in inhomogeneous layered manganites and multiferroic systems.
Method of measuring resonant frequencies of solids with parts per million resolution over a wide temperature range
Authors: Tozaki K. , Okazaki T. , Kojima A. , Yoshimura Y.
Published: May 2005

An apparatus has been developed for the measurement of the ultrasonic resonances of a solid cube or parallelepiped, which involves a method of excitation and detection. The key point is that a small reentrant-type microwave cavity is used in the apparatus. The excitation of the sample vibration is due to the electrostatic force between a metal-coated sample surface and the outer surface of the cavity. The resonant frequency of the sample is measured by taking advantage of the amplitude modulation of the characteristic resonant frequency of the cavity. This modulation is caused by the capacitance change due to the sample vibration. The apparatus is so small that it is mounted in the “mK-stabilized cell” developed previously, which has a temperature stability and/or resolution of the order of 1mK. The usefulness of the apparatus combined with the “mK-stabilized cell” has been demonstrated by the precise measurement of the resonant frequency of BaTiO3 single crystal at its phase transition, which is relevant to the change of its elastic modulus at the critical point.
Strong near-infrared photoluminescence in erbium/ytterbium codoped porous silicon
Authors: Luo L. , Zhang X. X. , Li K. F. , Cheah K. W. , Gong M. L. , Shi J. X. , Wong W. K.
Published: May 2005

Erbium ions and ytterbium ions (1021∕cm3) were electrochemically codoped into porous silicon. When compared with the Er-doped porous silicon we found two salient features in its photoluminescence. One is that the 1.54μm emission of Er3+ ions was 50 times stronger under 980nm laser excitation at room temperature. This is due to the high efficiency of the Yb3+→Er3+ energy transfer. The other is that the photoluminescence intensity increases rapidly with temperature, while that in Er-doped porous silicon decreases monotonically with temperature. Our results show that the codoped Er∕Yb porous silicon has a promising potential for the application in optical communications.
Phonon confinement effect of silicon nanowires synthesized by laser ablation
Authors: Fukata N. , Oshima T. , Murakami K. , Kizuka T. , Tsurui T. , Ito S.
Published: May 2005

A gradual downshift and asymmetric broadening of the Si optical phonon peak were observed by Raman scattering measurements of continuously thermally oxidized silicon nanowires (SiNWs) synthesized by laser ablation. This downshift and broadening can be interpreted by the phonon confinement effect. Further thermal oxidation produced a reverse change; namely, an upshift of the optical phonon peak. This is considered to be due to compressive stress since this stress was relieved by removing the oxide layers formed around the SiNW cores, resulting in a downshift of the optical phonon peak.
Phased-array electro-optic steering of large aperture laser beams using ferroelectrics
Authors: Scrymgeour David A. , Tian L. , Gopalan Venkatraman , Chauvin Daren , Schepler Kenneth L.
Published: May 2005

We present a device concept for scanning large (>1cm) laser beams using a domain microengineered ferroelectric device. In our design, the large input beam is divided into smaller beamlets, which are then individually deflected through an angle, and then recombined in the far-field to reconstruct the large beam. As a demonstration of this concept, a five-stage cascaded rectangular domain micropatterned scanner device with 13 beamlet channels was fabricated in LiTaO3 and was demonstrated to deflect a 1.064μm infrared laser beam by a total of 10.3° at 5.39kV∕mm.
Transverse and longitudinal surface plasmon resonances of a hexagonal array of gold nanorods embedded in an alumina matrix
Authors: McMillan Brian G. , Berlouis Léonard E. A. , Cruickshank Francis R. , Pugh David , Brevet Pierre-François
Published: May 2005

The specular reflectance from a hexagonal array of gold nanorods embedded in an alumina matrix supported on an aluminum substrate is reported. The rods were grown by electrodeposition of gold in an alumina template and were oriented with their long axis perpendicular to the film surface. Optical reflectance measurements performed with an incident light beam of S polarization only exhibited the transverse surface plasmon resonance whereas the measurements obtained with P polarization exhibited both transverse and longitudinal resonances. A model for the reflectance from a thin anisotropic film was developed and shown to be in agreement with the experimental data.
Arsenic activation in molecular beam epitaxy grown, in situ doped HgCdTe(211)
Authors: Boieriu P. , Grein C. H. , Jung H. S. , Garland J. , Nathan V.
Published: May 2005

Photovoltaic p-n junctions are the most significant active components of both current infrared photodetectors and advanced ones being developed. It is of the utmost importance to control both p- and n-type extrinsic doping. This letter addresses the issue of activating arsenic as a p-type dopant of Hg1−xCdxTe at temperatures sufficiently low that the integrity of p-n junctions and the intrinsic advantages of molecular beam epitaxy as a growth technique will not be compromised. The p-type activation of arsenic in (211)B Hg1−xCdxTe is reported after a two-stage anneal at temperatures below 300 °C for Cd compositions suitable for the sensing of long wavelength infrared radiation.