bluuebunny/crossref_metadata_2025 huggingface dataset:
Partial Union of Acute Scaphoid Fractures
Authors: SINGH H. P. , FORWARD D. , DAVIS T. R. C. , DAWSON J. S. , ONI J. A. , DOWNING N. D.
Published: July 2005

Sixty-six patients with acute scaphoid fractures were treated non-operatively in a below elbow plaster for 8 to 12 weeks and underwent CT scans along the longitudinal axis of the scaphoid at 12 to 18 weeks. These scans showed that 14 fractures had not united and that 30 had united throughout the whole cross-section of the scaphoid. The other 22 had partially united with bridging trabeculae in some areas of the cross-section. These 22 partial unions were graded as 0% to 24% union (0 cases), 25% to 49% union (5 cases), 50% to 74% union (7 cases), and 75% to 99% union (10 cases). The 12 patients who had less than 75% fracture union were followed-up further and nine underwent another CT scan at 23 to 40 weeks after the initial injury. These showed union across the whole of the cross-section of the fracture in seven cases and 75% to 99% union in the other two cases, who had full and painless wrist function. We conclude that partial union of the scaphoid is a common occurrence but, in most cases, it progresses to full union without the need for prolonged plaster immobilization.
Cardiac dimensions during extracorporeal membrane oxygenation
Authors: Tanke Ronald B. , Daniëls Otto , van Heijst Arno F. , van Lier Henk , Festen Cees
Published: July 2005

Our aim was to analyze left ventricular fractional shortening during extracorporeal membrane oxygenation under the influence of changing volume loading conditions induced by a ductal left-to-right shunt. In all patients, the fractional shortening was observed using echocardiography before, during, and after bypass, irrespective of the presence or absence of the ductal left-to-right shunt. During membrane oxygenation, there was a significant decrease in fractional shortening (p less than 0.001), with no difference before and after membrane oxygenation. A greater decrease in fractional shortening was observed in the group with a ductal left-to-right shunt when compared to patients lacking the ductal shunt (p less than 0.006). The diastolic diameter of the left ventricle also increased significantly during the membrane oxygenation in those patients with left-to-right ductal shunting. Moreover, the patients with left-to-right shunting showed a very severe decreased fractional shortening, lower than 10 per cent, with significantly greater frequency (p less than 0.05) during the course of membrane oxygenation.Conclusion:An important decrease in left ventricular fractional shortening is observed during veno-arterial extracorporeal membrane oxygenation. Left-to-right shunting during bypass, as seen in the patients with patency of the arterial duct, increases the loading conditions on the left ventricle, and produces a significant increase in left ventricular diastolic dimensions. Despite the effects of volume loading produced by the ductal shunt during bypass, the decrease in fractional shortening is significantly more pronounced for these patients. Therefore, during membrane oxygenation the volume loading produced by the ductal shunt is unable to prevent a decrease in left ventricular fractional shortening.
Levels of brain natriuretic peptide in children with right ventricular overload due to congenital cardiac disease
Authors: Mir Thomas S. , Falkenberg Jan , Friedrich Bernd , Gottschalk Urda , Lê Throng Phi , Laer Stephanie , Weil Jochen
Published: July 2005

Objective:To evaluate the role of the concentration of brain natriuretic peptide in the plasma, and its correlation with haemodynamic right ventricular parameters, in children with overload of the right ventricle due to congenital cardiac disease.Methods:We studied 31 children, with a mean age of 4.8 years, with volume or pressure overload of the right ventricle caused by congenital cardiac disease. Of the patients, 19 had undergone surgical biventricular correction of tetralogy of Fallot, 11 with pulmonary stenosis and 8 with pulmonary atresia, and 12 patients were studied prior to operations, 7 with atrial septal defects and 5 with anomalous pulmonary venous connections. We measured brain natriuretic peptide using Triage®, from Biosite, United States of America. We determined end-diastolic pressures of the right ventricle, and the peak ratio of right to left ventricular pressures, by cardiac catheterization and correlated them with concentrations of brain natriuretic peptide in the plasma.Results:The mean concentrations of brain natriuretic peptide were 87.7, with a range from 5 to 316, picograms per millilitre. Mean end-diastolic pressure in the right ventricle was 5.6, with a range from 2 to 10, millimetres of mercury, and the mean ratio of right to left ventricular pressure was 0.56, with a range from 0.24 to 1.03. There was a positive correlation between the concentrations of brain natriuretic peptide and the ratio of right to left ventricular pressure (r equal to 0.7844, p less than 0.0001) in all patients. These positive correlations remained when the children with tetralogy of Fallot, and those with atrial septal defects or anomalous pulmonary venous connection, were analysed as separate groups. We also found a weak correlation was shown between end-diastolic right ventricular pressure and concentrations of brain natriuretic peptide in the plasma (r equal to 0.5947, p equal to 0.0004).Conclusion:There is a significant correlation between right ventricular haemodynamic parameters and concentrations of brain natriuretic peptide in the plasma of children with right ventricular overload due to different types of congenital cardiac disease. The monitoring of brain natriuretic peptide may provide a non-invasive and safe quantitative follow up of the right ventricular pressure and volume overload in these patients.
Complications of paediatric interventional catheterisation: an analysis of risk factors
Authors: Agnoletti Gabriella , Bonnet Caroline , Boudjemline Younes , Le Bihan Christine , Bonnet Damien , Sidi Daniel , Bonhoeffer Philipp
Published: July 2005

Objectives:To identify predictive factors of complications occurring during paediatric interventional catheterisation.Background:Interventional paediatric catheterisation is still burdened by a substantial risk. Risk factors, however, have rarely been investigated.Methods:We analysed prospectively 1,022 interventional procedures performed over a period of 8 years, excluding 260 procedures for atrial septostomy. We considered several patient-related variables, specifically age, weight, and gender, type of procedure, times required for fluoroscopy and the overall procedure, technical challenge, and the severity of the clinical condition. We also analysed variables linked to the environment, specifically the date of the examination, whether the operator remained in training, the novelty of the material, any breakdown in the installation, and errors made by the operator. We classified complications as those without clinical consequence, those which proved lethal, those requiring cardiopulmonary resuscitation, elective or emergency surgery, hospitalisation in the intensive care unit, and those leading to recatheterisation.Results:Our average incidence of complications was 4.1 per cent, which did not change significantly during the period of study. Of the patients, 4 died, 7 needed urgent surgery, 5 elective surgery, 3 hospitalisation in intensive care unit, and 8 recatheterisation. Independent risk factors for complications were technical challenge, critical clinical condition, operator in training, operator error, and breakdown of the installation. Young age was not associated with a higher risk of complications. Patients in whom no cause for complication could be found, either related to their own features or the environment, had a risk of complication of 1.4 per cent (95 per cent confidence intervals from 0.7 to 2.5 per cent).Conclusions:Our data show that variables relating either to the patient or the environment of catheterisation are associated with an increased risk of procedural complications. Knowledge of the risk factors can improve the odds of paediatric interventional catheterisation.
Dilated cardiomyopathy presenting during fetal life
Authors: Sivasankaran Sivasubramonian , Sharland Gurleen K. , Simpson John M.
Published: July 2005

Objectives: To describe the echocardiographic features, underlying causes, and outcome of fetuses with dilated cardiomyopathy. Design: A retrospective observational study between 1983 and 2003 at a tertiary centre for fetal cardiology. Patients: Affected fetuses were identified using a computerised database. We included fetuses with dilation and reduced systolic function of either the right ventricle, left ventricle, or both. We excluded fetuses with abnormal cardiac connections, arrhythmias, or stenosis of the aortic or pulmonary valves. In all, we identified 50 fetuses, born to 46 mothers. Of the fetuses, 24 had biventricular cardiomyopathy, 17 had isolated right ventricular cardiomyopathy, and 9 had isolated left ventricular cardiomyopathy. Two-thirds of the fetuses (32) were hydropic at some point during gestation. Main outcomes: A cause of cardiomyopathy was identified in 37 cases (74 per cent). This was genetic or metabolic in 11 fetuses; infective in 11; fetal anaemia, without proven parvovirus infection, in 5; of cardiac origin in 5; and an association with renal disease in 5. In 10 cases (20 per cent), the pregnancy was terminated. Based on an intention to treat, the survival to delivery was 25 of 40 (62.5 per cent, 95 per cent confidence intervals from 46 to 77 per cent), at 28 days was 17 of 40 (42.5 per cent, 95 per cent confidence intervals from 27 to 59 per cent), and at 1 year was 15 of 40 (37.5 per cent, 95 per cent confidence intervals from 23 to 54 per cent). The overall survival of non-hydropic fetuses was 9 of 18 (50 per cent), compared to 6 of 32 (18 per cent) hydropic fetuses. Conclusions: Genetic, metabolic, infective, and cardiac diseases may present with dilated cardiomyopathy during fetal life. There is a high rate of spontaneous intra-uterine and early neonatal death. The prognosis is particularly poor for hydropic fetuses.
Prolonged treatment with prostaglandin in an infant born with extremely low weight
Authors: Barker Claire L. , Yates Robert W. , Kelsall A. Wilf
Published: July 2005

We describe an infant with duct-dependent cardiac disease diagnosed prenatally who was born prematurely, and at extremely low weight. Treatment by infusion of prostaglandin maintained ductal patency for 66 days, permitting weight to be gained whilst under the care of a regional unit for neonatal intensive care prior to transfer for palliative cardiac surgery.
Neurologische Entwicklung, Körperkoordination und Visuomotorik bei ehemals gesund entlassenen frühgeborenen Kindern im Alter von neun bis zwölf Jahren
Authors: Steiß Jens-Oliver , Langner Cornelia , Neuhäuser Gerhard
Published: July 2005

Zusammenfassung. Es wurden 31 als neurologisch unauffällig entlassene Frühgeborene (< 2500 g Geburtsgewicht, < 37 Schwangerschaftswochen) untersucht; zum Vergleich dienten reifgeborene Kinder. Im Alter von neun bis zwölf Jahren wurde durch eine neurologisch-motoskopische Untersuchung (nach Touwen) sowie mit dem Körperkoordinationstest für Kinder (KTK) und dem Leistungsdominanztest (LDT) vor allem die “Bewegungskoordination“ erfasst; das Verhalten während der Untersuchung wurde vergleichend beurteilt. Trotz äußerst geringer Risikofaktoren bei den ehemals frühgeborenen Kindern zeigten sich im Alter von neun bis zwölf Jahren signifikante Unterschiede bei der neurologisch-motoskopischen Untersuchung sowie im Körperkoordinationstest gegenüber den Kontrollen. Die Ergebnisse zeigen, dass langfristige Verlaufsstudien auch bei ehemals als gesund entlassenen frühgeborenen Kindern notwendig sind. Diese haben zwar nur ein leicht erhöhtes Risiko für langfristige Entwicklungsstörungen; der Anteil von auffälligen Kindern mit Störungen von Koordination und Visuomotorik ist jedoch vermehrt.
Allen Telescope Array digital processing requirements driven by radio frequency interference concerns
Authors: Harp G. R.
Published: July 2005

As a new generation radio telescope, the Allen Telescope Array (ATA) is a prototype for the Square Kilometer Array (SKA). Here we describe recently developed design constraints for the ATA digital signal processing chain as a case study for SKA processing. As radio frequency interference (RFI) becomes increasingly problematic for radio astronomy, radio telescopes must support a wide range of RFI mitigation strategies, including online adaptive RFI nulling. We observe that the requirements for digital accuracy and control speed are driven not by astronomical imaging but by RFI. This can be understood from the fact that high dynamic range and digital precision are necessary to remove strong RFI signals from the weak astronomical background and because RFI signals may change rapidly compared with celestial sources. We review and critique lines of reasoning that lead us to some of the design specifications for ATA digital processing, including these specifications: Beam former coefficients must be specified with at least 1° precision and at least once per millisecond to enable flexible RFI excision.
A new design for a very low frequency spaceborne radio interferometer
Authors: Oberoi Divya , Pinçon Jean‐Louis
Published: July 2005

The nontransparency and severe propagation effects of the terrestrial ionosphere make it impossible for Earth‐based instruments to study the universe at low radio frequencies. An exploration of the low‐frequency radio window with the resolution and sensitivity essential to meet the scientific objectives will necessarily require a dedicated satellite‐based interferometer operating at these frequencies. Such missions have been proposed in the literature for about the past 15 years. Today, the steady and impressive advances in technology and computing resources have brought us to the brink of a quantum jump in the performance and capabilities of such missions, increasing their scientific desirability manyfold. This paper presents the concept design which emerged from a study to investigate the feasibility of a low‐frequency satellite‐based interferometer operating in the frequency range 0.1–40 MHz titled Preparation for Radio Interferometry in Space. In place of trying to stretch and adapt the existing solutions to the requirements of very low frequency interferometry, this study attempts to tailor a design to meet its specific needs. The salient features of the design are an onboard correlator to reduce the data volumes to be transmitted to the Earth by about 2 orders of magnitude, use of three orthogonal dipoles in place of two to achieve better polarization characteristics, direct digitization of the entire radio frequency band of interest allowing broadband observations, an overlap in the observing frequency range with upcoming ground‐based instruments to aid in imaging and calibration, and an all‐sky imaging capability. The most constraining bottleneck for the present design is the large intraconstellation telemetry requirement. It is expected that technological solutions to meet this requirement will be found in the near future as other formation‐flying missions which share this requirement emerge.
Comparison of electric fields and density structures seen in simulations and satellite observations
Authors: Singh Nagendra , Deverapalli C. , Khazanov I.
Published: July 2005

There are now clear observations of large parallel electric fields (E∥) from Polar and FAST in the auroral upward‐current region (UCR). Such fields in some events are associated with large perpendicular electric fields (E⊥) and density cavities while in others they could occur without them. The observed features of the fields and density are found to be compatible with the spatial structures seen in a simulated U‐shaped potential structure (PS) using a 2.5D electrostatic code. The spatial and temporal evolution of the U‐shaped PS (USPS) including its upward and downward motions and its striations into thin long potential structures suggest a variety of signatures in the satellite detection of E∥ and E⊥.
Measurements of O3, NO2 and Temperature during the 2004 Canadian Arctic ACE Validation Campaign
Authors: Kerzenmacher Tobias E. , Walker Kaley A. , Strong Kimberly , Berman Richard , Bernath Peter F. , Boone Chris D. , Drummond James R. , Fast Hans , Fraser Annemarie , MacQuarrie Keith , Midwinter Clive , Sung Keeyoon , McElroy C. Thomas , Mittermeier Richard L. , Walker Jennifer , Wu Hongjiang
Published: July 2005

The 2004 Canadian Arctic ACE Validation Campaign was conducted to provide correlative data for validating measurements from the Atmospheric Chemistry Experiment (ACE) satellite mission. These measurements were made at Eureka, Nunavut during polar springtime 2004. Six ground‐based instruments were operated during the intensive phase of the campaign and ozonesondes and radiosondes were flown. During this time, ACE‐FTS and ACE‐MAESTRO were performing solar‐occultation measurements over the Canadian Arctic. We report the first comparisons between campaign measurements and those from ACE, focusing on O3, NO2 and temperature. Initial mean O3 profiles from ACE‐FTS and ACE‐MAESTRO agree to within 20% between 10 and 30 km, and the NO2 profiles agree to within 40% between 17 and 40 km, which is within the standard deviations. The ACE‐FTS temperature profiles agree to better than 2.5 K with the radiosonde temperatures from 10 to 32 km and with the lidar temperatures from 17 to 45 km.
Electron anisotropy constraint in the magnetosheath: Cluster observations
Authors: Gary S. Peter , Lavraud Benoit , Thomsen Michelle F. , Lefebvre Bertrand , Schwartz Steven J.
Published: July 2005

The whistler anisotropy instability is driven by the condition T⊥e/T∥e > 1, where the subscript e denotes electrons and the other subscripts denote directions relative to the background magnetic field Bo. Instability growth leads to enhanced field fluctuations which scatter the electrons; theory and simulations show that this scattering imposes an upper bound on the electron anisotropy in the form T⊥e/T∥e − 1 = with fitting parameters 0.1 ≲ Se ≲ 1 and 0.5 ≲ αe < 0.7 over 0.10 ≤ β∥e ≤ 1.0 where β∥e = 8πneT∥e/Bo2. Here measurements from the PEACE instrument on the Cluster 1 spacecraft show that electron anisotropies in two crossings of the dayside terrestrial magnetosheath are constrained statistically by this equation with Se ≃ 0.2 and αe ≃ 0.6. This is the first reported observation of this constraint in a space plasma.
Brain Endothelial Hemostasis Regulation by Pericytes
Authors: Kim Jeong Ai , Tran Nam D , Li Zhen , Yang Fan , Zhou Weilin , Fisher Mark J
Published: July 2005

Pericytes are known to regulate brain capillary endothelial functions. The purpose of this study was to define the hemostatic regulatory role of human brain pericytes. We used blood–brain barrier models consisting of human pericytes grown on transwell membrane inserts and cocultured with human brain microvascular endothelial cells (HBEC), or pericytes grown in direct contact with HBEC. When grown in cocultures in which pericytes were physically separated from endothelial cells, pericytes induced significant changes in endothelial tissue plasminogen activator (tPA) messenger ribonucleic acid (mRNA) and protein: tPA mRNA level was decreased in pericyte cocultures (52% ± 25% of monocultures, P < 0.05) and tPA protein level was decreased (66% ± 23% of monocultures, P < 0.05). Pericyte effects on endothelial fibrinolysis were enhanced when the two cell types were cocultured in direct contact, with tPA protein reduced in cocultures compared with monocultures (25% ± 15% of monocultures, P < 0.05). Endotoxin (lipopolysaccharide (LPS)), used as a standardized stimulus to define brain-specific inflammation-induced change, amplified pericyteinduced enhanced release of the tPA inhibitor plasminogen activator inhibitor-1 (PAI-1); the latter was released by endothelial cells first cocultured with pericytes and then incubated with LPS in the absence of pericytes. Pericytes (in contrast to endothelial cells and astrocytes) were found to be the principal in vitro source of the serpin protease nexin-1 (PN-1), known to have primarily antithrombin effects. These in vitro findings suggest that pericytes negatively regulate brain endothelial cell fibrinolysis, while pericyte expression of PN-1 may provide endogenous anticoagulant activity.
Density-functional theory (hyper)polarizabilities of push-pull π-conjugated systems: Treatment of exact exchange and role of correlation
Authors: Bulat Felipe A. , Toro-Labbé Alejandro , Champagne Benoît , Kirtman Bernard , Yang Weitao
Published: July 2005

The performance of the optimized effective potential procedure for exact exchange in calculating static electric-field response properties of push-pull π-conjugated systems has been studied, with an emphasis on NO2–(CHCH)n–NH2 chains. Good agreement with Hartree–Fock dipole moments and (hyper)polarizabilities is obtained; particularly noteworthy is the chain length dependence for β∕n. Thus, the problem that conventional density-functional theory functionals dramatically overestimate these properties is largely solved, although there remains a significant correlation contribution that cannot be accounted for with current correlation functionals.
Renner–Teller vibronic analysis for a tetra-atomic molecule. I. The effective Hamiltonian and matrix elements
Authors: He Sheng-Gui , Clouthier Dennis J.
Published: July 2005

The effective vibronic Hamiltonian for a linear tetra-atomic molecule in a Π state has been investigated. In addition to the usual vibrational and Renner–Teller coupling terms, the bending mode anharmonicity, spin-orbit coupling, and Fermi resonance interactions have been added to the model. Terms in the Hamiltonian up to the fourth order are given explicitly for molecules of C∞υ symmetry and simplifications for symmetric D∞h molecules are discussed. The matrix elements for the HCCS free radical have been obtained and are used to analyze the observed ground-state levels of HCCS and DCCS in a companion paper. The Sears resonance vibronic interaction that couples levels with the selection rules ΔK=±1, ΔΣ=∓1, and ΔP=0 has also been studied and the matrix elements derived. The determinable combinations of signs for the major parameters in the model are discussed.
Renner–Teller vibronic analysis for a tetra-atomic molecule. II. The ground state of the HCCS free radical
Authors: He Sheng-Gui , Clouthier Dennis J.
Published: July 2005

We have studied the tetra-atomic Renner–Teller effect in the ground state of the jet-cooled HCCS and DCCS free radicals. The reactive intermediates were produced in a pulsed discharge jet using thiophene or deuterated thiophene precursors and the ground-state vibronic energies were measured using the single vibronic level emission spectroscopy technique. In HCCS, emission and fluorescence depletion experiments proved that some previously unassigned laser-induced fluorescence (LIF) features were anomalous Δ3∕22−Π3∕22 transitions, which gave information on several ground-state Δ3∕22 levels. In DCCS, rotational mixing of the excited state v′=0(Π3∕22) level with the 41(1Σ1∕22) level allowed several ground-state Σ2 levels to be observed in emission. In addition, we have shown that some previously unassigned weak LIF bands of DCCS are anomalous Π1∕22−Π3∕22 transitions which have allowed us to accurately measure the ground-state spin-orbit splitting (259.0cm−1) for the first time. All of the expected ground-state Π3∕22 levels and the majority of the Π1∕22 levels up to 1700cm−1 have been observed for both isotopomers. The data have been fitted by an effective Hamiltonian matrix treatment that included Renner–Teller, spin-orbit coupling, anharmonicity, and Fermi resonance effects for the two bending vibrations and the CS stretching mode. This has allowed an unusually complete description of the orbital angular momentum coupling effects, including the determination of the ϵ4, ϵ5, and ϵ45 terms for the first time. Subtle effects in both the LIF and emission spectra signal the presence of Sears resonances in both the ground and excited states of these radicals.
Composition and temperature dependence of cesium-borate glasses by molecular dynamics
Authors: Vegiri Alice , Varsamis Cristos-Platon E. , Kamitsos Efstratios I.
Published: July 2005

The structural aspects of xCs2O-(1−x)B2O3 glasses have been investigated by molecular dynamics as functions of Cs2O content (x=0.2, 0.3, and 0.4) and temperature (T=300 and 1250 K). The tetrahedral (BØ4−) and triangular (BØ3,BØ2O−, and BØO22−) short-range order borate units were found to be the structure-building entities of the simulated glasses [Ø=bridging oxygen (BO) and O−=nonbridging oxygen (NBO) atom]. The increase of Cs2O content results in the progressive increase of the NBO-containing triangle population at the expense of the BØ4− tetrahedral units. The same effect is caused by temperature increase at a fixed Cs2O content, and this was associated with the “fragile” characteristics of alkali borate glasses. A comparison of simulated Cs and Li borates showed very similar structures at x=0.2, but dissimilar ones when the alkali content exceeds this composition. In particular, for x>0.2 Cs borates exhibit a preference for NBO formation relative to Li borates. Differences in the microstructure of sites hosting Cs ions were found, and this permits their classification into bridging (b type) and nonbridging type (nb type) of sites. b-type sites consist exclusively of BO atoms, while both BO and NBO atoms participate in nb-type sites. These differences in Cs-site local bonding characteristics were found to be reflected on the Cs–O(site) vibration frequencies. Also, the computed Cs–O vibrational responses for simulated Cs borates were found to compare well with experimental far-infrared spectra.
Universal isotope effect in thermal diffusion of mixtures containing cyclohexane and cyclohexane-d12
Authors: Wittko G. , Köhler W.
Published: July 2005

The Soret coefficients ST of the liquids acetone, benzene, benzene-d1, 1,3,5-benzene-d3, benzene-d5, benzene-C613, benzene-d6, n-hexane, toluene, 1,2,3,4-tetrahydronaphthalene, isobutylbenzene, and 1,6-dibromohexane have been measured in protonated and perdeuterated cyclohexane by a transient holographic grating technique. It has been found that ST can be either positive or negative and even change its sign as a function of concentration. The isotope effect ΔST=−0.99×10−3K−1, which is the change of ST after isotopic substitution of cyclohexane, neither depends on concentration nor on the nature of the mixing partner. Only in the case of the polar acetone is ΔST approximately 30% larger but still concentration independent. Based on the experimental findings, some general conclusions about the dependence of the Soret coefficient on molecular properties are drawn.
Pulsed-field ionization electron spectroscopy and binding energies of alkali metal-dimethyl ether and -dimethoxyethane complexes
Authors: Sohnlein Bradford R. , Li Shenggang , Fuller Jason F. , Yang Dong-Sheng
Published: July 2005

Lithium and sodium complexes of dimethyl ether (DME) and dimethoxyethane (DXE) were produced by reactions of laser-vaporized metal atoms with organic vapors in a pulsed nozzle cluster source. The mono-ligand complexes were studied by photoionization and pulsed field ionization zero electron kinetic energy (ZEKE) spectroscopy. Vibrationally resolved ZEKE spectra were obtained for Li(DME), Na(DME) and Li(DXE) and a photoionization efficiency spectrum for Na(DXE). The ZEKE spectra were analyzed by comparing with the spectra of other metal-ether complexes and with electronic structure calculations and spectral simulations. Major vibrations measured for the M(DME) (M=Li,Na) ions were M–O and C–O stretches and M–O–C and C–O–C bends. These vibrations and additional O–Li–O and O–C–C–O bends were observed for the Li(DXE) ion. The M(DME) complexes were in C2v symmetry with the metal atom binding to oxygen, whereas Li(DXE) was in a C2 ring configuration with the Li atom attaching to both oxygen atoms. Moreover, the ionization energies of these complexes were measured from the ZEKE or photoionization spectra and bond dissociation energies were derived from a thermodynamic cycle.
Anomalous vibrational energy diffusion in carbon nanotubes
Authors: Zhang Gang , Li Baowen
Published: July 2005

We study the vibrational energy diffusion in single-walled carbon nanotubes by using the molecular-dynamics method. It is found that energy transports ballistically at low temperature and superdiffusively at room temperature. The velocity of energy transport along the axis in carbon nanotube at room temperature is about 0.10Å∕fs. It is also found that energy transport in carbon nanotube is different from that one in one-dimensional carbon lattice with the same interaction potential.
Plasmon hybridization in nanoshell dimers
Authors: Brandl Daniel W. , Oubre Chris , Nordlander Peter
Published: July 2005

We extend the plasmon hybridization method to investigate the plasmon modes of metallic nanoshell dimers. The formalism is also generalized to include the effects of dielectric backgrounds. It is shown that the presence of dielectrics shifts the plasmon resonances of the individual nanoparticles to lower energies and screens their interaction in the dimer configuration. The net result is a redshift of dimer energies compared to the system without dielectrics and a weaker dependence of the dimer plasmon energies on dimer separation. We calculate the plasmon energies and optical absorption of nanoshell dimers as a function of dimer separation. The results are in excellent agreement with the results of finite difference time domain simulations.
Time-dependent density-functional theory based on optimized effective potentials for van der Waals forces
Authors: Hirata So
Published: July 2005

The C6 coefficients of van der Waals interactions have been evaluated by the dynamic polarizabilities at imaginary frequencies computed by time-dependent density-functional theory using the optimized effective potentials. The C6 coefficients thus obtained agree accurately with those from the exact-exchange counterpart in ab initio molecular-orbital theory.
Ab initio prediction of the infrared-absorption spectrum of the C2Cl radical
Authors: Tarroni Riccardo , Carter Stuart
Published: July 2005

The three lowest (12A′, 22A′, and 12A″) potential-energy surfaces of the C2Cl radical, correlating at linear geometries with Σ+2 and Π2 states, have been studied ab initio using a large basis set and multireference configuration-interaction techniques. The electronic ground state is confirmed to be bent with a very low barrier to linearity, due to the strong nonadiabatic electronic interactions taking place in this system. The rovibronic energy levels of the C12C12Cl35 isotopomer and the absolute absorption intensities at a temperature of 5K have been calculated, to an upper limit of 2000cm−1, using diabatic potential-energy and dipole moment surfaces and a recently developed variational method. The resulting vibronic states arise from a strong mixture of all the three electronic components and their assignments are intrinsically ambiguous.
Quasiperiodic trajectories in the unimolecular dissociation of ethyl radicals by time-frequency analysis
Authors: Bach Andreas , Hostettler Jonas M. , Chen Peter
Published: July 2005

Direct classical trajectory calculations for ethyl radical, C2H5, at the HCTH147@6-31+G**∕6-31G** level of theory support the experimental observation that the dissociation of highly excited ethyl radicals to ethylene and and a hydrogen atom can occur much more slowly than predicted by statistical rate theories. Only 78% of the trajectories of ethyl radicals prepared in a microcanonical ensemble with 120-kcal∕mol excitation energy above the zero-point energy and zero total angular momentum dissociate to form C2H4+H. The remaining hot ground-state ethyl radicals have a lifetime of ⪢2ps, during which a time-frequency analysis finds them trapped for extended periods of time in long-lived quasiperiodic trajectories.
A metal-dielectric antenna for terahertz near-field imaging
Authors: Klein N. , Lahl P. , Poppe U. , Kadlec F. , Kužel P.
Published: July 2005

We present an antenna-based approach to near-field imaging and spectroscopy, which can be used for both continuous-wave and pulsed broadband electromagnetic radiations from microwave to terahertz frequencies. Our near-field antenna consists of a rectangular-shaped block of low-loss dielectric material sharpened to a pyramidal tip which is partially metallized and terminated by a micron-sized plane facet. At this facet the entire energy of the incident wave is concentrated as a very high but strongly localized electric field, which can be used as a sensitive near-field microprobe for electromagnetic radiation. Currently, experiments in reflection geometry with pulsed terahertz radiation and continuous-wave radiation near 80GHz reveal a frequency-independent spatial resolution of about 20μm corresponding to λ∕200 at 80GHz, which is only limited by the size of the facet terminating the tip.
Three-dimensional imaging of individual hafnium atoms inside a semiconductor device
Authors: van Benthem Klaus , Lupini Andrew R. , Kim Miyoung , Baik Hion Suck , Doh SeokJoo , Lee Jong-Ho , Oxley Mark P. , Findlay Scott D. , Allen Leslie J. , Luck Julia T. , Pennycook Stephen J.
Published: July 2005

The aberration-corrected scanning transmission electron microscope allows probes to be formed with less than 1-Å diameter, providing sufficient sensitivity to observe individual Hf atoms within the SiO2 passivating layer of a HfO2∕SiO2∕Si alternative gate dielectric stack. Furthermore, the depth resolution is sufficient to localize the atom positions to half-nanometer precision in the third dimension. From a through-focal series of images, we demonstrate a three-dimensional reconstruction of the Hf atom sites, representing a three-dimensional map of potential breakdown sites within the gate dielectric.
Investigation of metal diffusion into polymers by ab initio molecular dynamics
Authors: Dai Ling , Yang Shuo-Wang , Chen Xian-Tong , Wu Ping , Tan V. B. C.
Published: July 2005

Ab initio molecular dynamics simulations were performed to study the motion of single metal atoms and atom clusters of Cu and Ta in SiLK-like polymers to gain an insight into their diffusion mechanisms and characteristics. The analysis suggests that Cu atom motions are largely affected by jumps between cavities inside the polymer and that Ta is more sluggish than Cu not only because of its larger mass but also because of stronger affinity to the polymers. It was also found that crosslinking within polymers of the same density does not significantly affect the motions of the metal atoms or clusters.
Single-molecule DNA flexibility in the presence of base-pair mismatch
Authors: Schallhorn Kathryn A. , Freedman Katherine O. , Moore Jessica M. , Lin Jun , Ke Pu Chun
Published: July 2005

The conformational changes of a 22 base-pair double-stranded DNA, anchored via one end to a quartz substrate, have been characterized using a single-pair fluorescence resonance energy transfer technique. Base-pair mismatch, a major form of DNA damage, has been found to decrease the energy transfer between a fluorescence donor and an acceptor attached to the two ends of DNA molecules with 3 and 7 mismatches, by 4.4% and 10.4%, respectively, as compared to that for perfectly matched DNA. This result suggests that the disruption of the hydrogen bonds in damaged DNA leads to increased contour length and improved flexibility.
Single-mode vertical-cavity surface-emitting laser with ring-shaped light-emitting aperture
Authors: Shi Jin-Wei , Jiang C.-H. , Chen K.-M. , Yen J.-L. , Yang Ying-Jay
Published: July 2005

In this letter, we demonstrate a single-mode vertical-cavity surface-emitting laser (VCSEL) with a ring-shaped light-emitting aperture, which is realized by the Zn diffusion technique, at a wavelength of 850nm. Relative to the control VCSEL with an ordinary circular aperture and the same geometry and size, the demonstrated device can suppress the higher-order transverse mode more effectively without affecting the threshold current and output power. Compared with typical reported single-mode VCSELs, a larger light-emitting aperture and current-confined area with a smaller divergence angle of the output beam, and lower differential resistance are achieved with the present structure.
Gigahertz-range electro-acoustic devices based on pseudo-surface-acoustic waves in AlN∕diamond∕Si structures
Authors: Benetti M. , Cannatà D. , Di Pietrantonio F. , Fedosov V. I. , Verona E.
Published: July 2005

Diamond and AlN are, respectively, the nonpiezoelectric and the piezoelectric materials showing the highest acoustic velocities. Consequently, pseudo-surface-acoustic waves (PSAWs) in AlN∕diamond structures exhibit the highest surface wave velocities among all known layered structures. Phase velocity dispersion curves and attenuation for PSAW propagating along this structure have been calculated for different electrical boundary conditions. An experimental delay line, designed to operate at low PSAW attenuation conditions, as predicted by theoretical results, has been implemented and tested. A good accordance between experimental results and theoretical predictions was found. It is expected that devices based on PSAW propagation in AlN∕diamond structures are suitable to operate at frequencies several times higher than those of available devices, at a given linewidth resolution limit in the transducers technology.
Investigation of inflammable liquids by terahertz spectroscopy
Authors: Ikeda Takeshi , Matsushita Akira , Tatsuno Michiaki , Minami Yukio , Yamaguchi Mariko , Yamamoto Kohji , Tani Masahiko , Hangyo Masanori
Published: July 2005

We have examined a nondestructive and contactless screening method for water and inflammable liquids stored in common beverage plastic bottles by the terahertz time-domain spectroscopy. No THz transmission has been observed between 10 and 60cm−1 for 45-mm-thick water in plastic bottles. Part of the THz wave, on the other hand, has been transmitted through the commercially available inflammable liquids in the same bottles. The differences in the absorption intensities and the refractive indices in the THz region, which reflect the ingredients of organic compounds, allow us to distinguish these inflammable liquids. We confirm that the screening method based on the THz transmission can be applied to classifying the commercially available inflammable liquids stored in plastic bottles and to distinguishing these inflammable liquids from water as well.
Anomalous electrorheological behavior of ZnO nanowires
Authors: Feng P. , Wan Q. , Fu X. Q. , Wang T. H. , Tian Y.
Published: July 2005

We observe an anomalous electrorheological (ER) behavior of suspensions composed of ZnO nanowires and silicone oil. In contrast to the usual ER behavior, a decrease in viscosity of the suspensions is observed. Such an anomalous behavior results from the migration of ZnO nanowires to the electrodes under a dc electric field. The migration leads to a relatively pure silicone oil zone between the electrodes, as confirmed by optical microscope observations. The occurrence of the electrophoresis is proposed as the origin of the decrease in shear stress.
Highly efficient and stable luminescence of nanocrystalline porous silicon treated by high-pressure water vapor annealing
Authors: Gelloz B. , Kojima A. , Koshida N.
Published: July 2005

The effects of a treatment based on high-pressure water vapor annealing (HWA) on nanocrystalline porous silicon have been investigated in terms of the photoluminescence (PL) efficiency and stability. For originally nonluminescent samples with a relatively low porosity, the treatment produces highly efficient and stable luminescent nanocrystalline-Si (nc-Si) layers without affecting the emission wavelength. Under appropriate conditions of pressure (2.6 MPa) and temperature (260 °C), the PL external quantum efficiency reaches 23% at room temperature. Electron-spin-resonance and infrared absorption analyses show that the HWA treatment promotes surface oxidation of nc-Si under a minimized mechanical stress and consequently generates sufficiently passivated nc-Si∕SiO2 interfaces with an extremely low nonradiative defect density. This causes a drastic enhancement in the PL efficiency associated with a strong localization of excitons in nc-Si. As a practical approach, the HWA technique is very useful for fabrication of efficient and stable optoelectronic nc-Si devices.
The structure of the 80S ribosome from
Trypanosoma cruzi
reveals unique rRNA components
Authors: Gao Haixiao , Ayub Maximiliano Juri , Levin Mariano J. , Frank Joachim
Published: July 2005

We present analysis, by cryo-electron microscopy and single-particle reconstruction, of the structure of the 80S ribosome from
Trypanosoma cruzi
, the kinetoplastid protozoan pathogen that causes Chagas disease. The density map of the
T. cruzi
80S ribosome shows the phylogenetically conserved eukaryotic rRNA core structure, together with distinctive structural features in both the small and large subunits. Remarkably, a previously undescribed helical structure appears in the small subunit in the vicinity of the mRNA exit channel. We propose that this rRNA structure likely participates in the recruitment of ribosome onto the 5′ end of mRNA, in facilitating and modulating the initiation of translation that is unique to the trypanosomes.
Intrinsically photosensitive retinal ganglion cells detect light with a vitamin A-based photopigment, melanopsin
Authors: Fu Yingbin , Zhong Haining , Wang Min-Hua H. , Luo Dong-Gen , Liao Hsi-Wen , Maeda Hidetaka , Hattar Samer , Frishman Laura J. , Yau King-Wai
Published: July 2005

In mammals, intrinsically photosensitive retinal ganglion cells (ipRGCs) mediate non-image-forming visual functions such as pupillary light reflex (PLR) and circadian photoentrainment. This photosensitivity requires melanopsin, an invertebrate opsin-like protein expressed by the ipRGCs. The precise role of melanopsin remains uncertain. One suggestion has been that melanopsin may be a photoisomerase, serving to regenerate an unidentified pigment in ipRGCs. This possibility was echoed by a recent report that melanopsin is expressed also in the mouse retinal pigment epithelium (RPE), a key center for regeneration of rod and cone pigments. To address this question, we studied mice lacking RPE65, a protein essential for the regeneration of rod and cone pigments.
Rpe65
-

/

-
ipRGCs were ≈20- to 40-fold less photosensitive than normal at both single-cell and behavioral (PLR) levels but were rescued by exogenous 9-
cis
-retinal (an 11-
cis
-retinal analog), indicating the requirement of a vitamin A-based chromophore for ipRGC photosensitivity. In contrast, 9-
cis
-retinal was unable to restore intrinsic photosensitivity to melanopsin-ablated ipRGCs, arguing against melanopsin functioning merely in photopigment regeneration. Interestingly, exogenous
all-trans
-retinal was also able to rescue the low sensitivity of
rpe65
-

/

-
ipRGCs, suggesting that melanopsin could be a bistable pigment. Finally, we detected no melanopsin in the RPE and no changes in rod and cone sensitivities due to melanopsin ablation. Together, these results strongly suggest that melanopsin is the photopigment in the ipRGCs.
Neuronal calcium sensor-1 potentiates glucose-dependent exocytosis in pancreatic β cells through activation of phosphatidylinositol 4-kinase β
Authors: Gromada Jesper , Bark Christina , Smidt Kamille , Efanov Alexander M. , Janson Juliette , Mandic Slavena A. , Webb Dominic-Luc , Zhang Wei , Meister Björn , Jeromin Andreas , Berggren Per-Olof
Published: July 2005

Cytosolic free Ca
2+
plays an important role in the molecular mechanisms leading to regulated insulin secretion by the pancreatic β cell. A number of Ca
2+
-binding proteins have been implicated in this process. Here, we define the role of the Ca
2+
-binding protein neuronal Ca
2+
sensor-1 (NCS-1) in insulin secretion. In pancreatic β cells, NCS-1 increases exocytosis by promoting the priming of secretory granules for release and increasing the number of granules residing in the readily releasable pool. The effect of NCS-1 on exocytosis is mediated through an increase in phosphatidylinositol (PI) 4-kinase β activity and the generation of phosphoinositides, specifically PI 4-phosphate and PI 4,5-bisphosphate. In turn, PI 4,5-bisphosphate controls exocytosis through the Ca
2+
-dependent activator protein for secretion present in β cells. Our results provide evidence for an essential role of phosphoinositide synthesis in the regulation of glucose-induced insulin secretion by the pancreatic β cell. We also demonstrate that NCS-1 and its downstream target, PI 4-kinase β, are critical players in this process by virtue of their capacity to regulate the release competence of the secretory granules.
Remarks concerning linear characters of reflection groups
Authors: Lehrer G.
Published: July 2005

Let

G
G

be a finite group generated by unitary reflections in a Hermitian space

V
V

, and let

ζ
\zeta

be a root of unity. Let

E
E

be a subspace of

V
V

, maximal with respect to the property of being a

ζ
\zeta

-eigenspace of an element of

G
G

, and let

C
C

be the parabolic subgroup of elements fixing

E
E

pointwise. If

χ
\chi

is any linear character of

G
G

, we give a condition for the restriction of

χ
\chi

to

C
C

to be trivial in terms of the invariant theory of

G
G

, and give a formula for the polynomial

∑

x
∈
G

χ
(
x
)

T

d
(
x
,
ζ
)

\sum _{x\in G}\chi (x)T^{d(x,\zeta )}

, where

d
(
x
,
ζ
)

d(x,\zeta )

is the dimension of the

ζ
\zeta

-eigenspace of

x
x

. Applications include criteria for regularity, and new connections between the invariant theory and the structure of

G
G

.
Automatic differentiability and characterization of cocycles of holomorphic flows
Authors: Jafari Farhad , Tonev Thomas , Toneva Elena
Published: July 2005

In this paper we prove that cocycles of holomorphic flows on domains in the complex plane are automatically differentiable with respect to the flow parameter, and their derivatives are holomorphic functions. We use this result to show that, on simply connected domains, an additive cocycle is a coboundary if and only if this cocycle vanishes at the fixed point of the flow.
Cdc42 Is Not Essential for Filopodium Formation, Directed Migration, Cell Polarization, and Mitosis in Fibroblastoid Cells
Authors: Czuchra Aleksandra , Wu Xunwei , Meyer Hannelore , van Hengel Jolanda , Schroeder Timm , Geffers Robert , Rottner Klemens , Brakebusch Cord
Published: July 2005

Cdc42 is a small GTPase involved in the regulation of the cytoskeleton and cell polarity. To test whether Cdc42 has an essential role in the formation of filopodia or directed cell migration, we generated Cdc42-deficient fibroblastoid cells by conditional gene inactivation. We report here that loss of Cdc42 did not affect filopodium or lamellipodium formation and had no significant influence on the speed of directed migration nor on mitosis. Cdc42-deficient cells displayed a more elongated cell shape and had a reduced area. Furthermore, directionality during migration and reorientation of the Golgi apparatus into the direction of migration was decreased. However, expression of dominant negative Cdc42 in Cdc42-null cells resulted in strongly reduced directed migration, severely reduced single cell directionality, and complete loss of Golgi polarization and of directionality of protrusion formation toward the wound, as well as membrane blebbing. Thus, our data show that besides Cdc42 additional GTPases of the Rho-family, which share GEFs with Cdc42, are involved in the establishment and maintenance of cell polarity during directed migration.