bluuebunny/crossref_metadata_2025 huggingface dataset:
Decay rates of inner-valence excitations in noble gas atoms
Authors: Gokhberg K. , Averbukh V. , Cederbaum L. S.
Published: April 2007

A Fano - algebraic diagrammatic construction - Stieltjes method has been recently developed for ab initio calculations of nonradiative decay rates [V. Averbukh and L. S. Cederbaum, J. Chem. Phys. 123, 204107 (2005)] of singly ionized states. In the present work this method is generalized for the case of electronic decay of excited states. The decay widths of autoionizing inner-valence-excited states of Ne, Ar, and Kr are calculated. Apart from the lowest excitation of Kr, they are found to be in good to excellent agreement with the experimental values. Comparison with the other theoretical studies shows that in many cases the new method performs better than the previously available techniques.
Laser spectroscopy and dynamics of the jet-cooled AsH2 free radical
Authors: He Sheng-Gui , Clouthier Dennis J.
Published: April 2007

The ÃA12-X̃B12 electronic transition of the jet-cooled AsH2 free radical has been studied by laser-induced fluorescence (LIF), wavelength-resolved emission, and fluorescence lifetime measurements. The radical was produced by a pulsed electric discharge through a mixture of arsine (AsH3) and high pressure argon at the exit of a pulsed valve. Nine vibronic bands were identified by LIF spectroscopy in the 505–400nm region, including a long progression in the bending mode and two bands (101 and 101201) involving the excited state As-H symmetric stretch. Single vibronic level emission spectra showed similar activity in the bending and symmetric stretching frequencies of the ground state. High-resolution spectra of the 000 band exhibited large spin splittings and small, resolved arsenic hyperfine splittings, due to a substantial Fermi contact interaction in the excited state. The rotational constants obtained in the analysis gave effective molecular structures of r0″=1.5183(1)Å, θ0″=90.75(1)° and r0′=1.4830(1)Å, θ0′=123.10(2)°. The excited state fluorescence lifetimes vary dramatically with rovibronic state, from a single value of 1.4μs to many with lifetimes less than 10ns, behavior which the authors interpret as signaling the onset of a predissociative process near the zero-point level of the ground state.
Photoinduced effect in charge-ordering La0.5Ca0.5MnO3 film
Authors: Zhao S. G. , Jin K. X. , Chen C. L.
Published: April 2007

Charge-ordered La0.5Ca0.5MnO3 film has been deposited on (100)-LaAlO3 substrate using rf magnetron sputtering method. X-ray diffraction analysis shows that the bulk has orthorhombic structure and the film has the better epitaxial character. The charge-ordering transition temperature is about 280 K by fitting the resistance-temperature curve using the variable-range hopping model. The decrease in the resistance of the film irradiated by the laser is caused by the delocalization effect of the correlated electron system. The photoinduced relaxation exhibits different processes when the laser is on and off, which can be attributed to thermal fluctuation.
Changes in surface topography of amorphous silicon germanium films after light soaking
Authors: Agarwal Pratima , Srivastava Alok , Deva Dinesh
Published: April 2007

Light-induced metastable degradation of hydrogenated amorphous silicon and silicon germanium thin films (a-SiGe:H) is conjectured to be accompanied by structural changes but there has not been a direct measurement of the same. We measure the surface topography of these films in the annealed and the light soaked state using atomic force microscopy. We quantified the surface topography in terms of surface roughness and find that the surface roughness increases after light soaking. Our results provide direct evidence of the light-induced structural changes in these films.
Wettability study of modified silicon dioxide surface using environmental scanning electron microscopy
Authors: Aronov Daniel , Rosenman Gil , Barkay Zahava
Published: April 2007

The wettability analysis is often used to characterize a surface in micro and nanometer scale. At these small scales, effects of the contact line tension are also expected to play a significant role. Wettability effect is studied using environmental scanning electron microscopy on silicon dioxide surface modified by a low-energy electron irradiation method. Electron-induced wettability variation and patterning at micrometer scale on silicon dioxide substrate allow investigating the contact angle dependence on the water droplet line curvature and calculating values of the line tension of a three-phase system (solid-liquid-vapor) of about 10−9 J/m that is consistent with theoretical estimations. It is found that the sign of the line tension alters from positive for hydrophilic surface to negative for hydrophobic one.
Three-dimensional analysis of microwave generated plasmas with extended planar laser-induced fluorescence
Authors: Stopper U. , Lindner P. , Schumacher U.
Published: April 2007

We present the development and application of a diagnostic system for the analysis of microwave generated low-pressure plasmas, which might also be used for the investigation of the edge regions in magnetically confined fusion plasmas. Our method uses planar laser-induced fluorescence, which is produced by excitation of neutral metastable atoms through a short, intense, pulsed laser. The beam expansion optics consist of an uncommon setup of four lenses. By controlled shifting of an element of the optics sideways, the location of the laser sheet in the plasma is scanned perpendicular to the excitation plane. Together with a spectrometer observing different observation volumes along the beam path, we are able to map absolute three-dimensional (3D) population density distributions of the metastable (P21∕2o)3s[1∕2]0o state of Ne I in an electron cyclotron resonance heating (ECRH) plasma. This optical tomography system was used to study the influence of the microwave power and mode on the spatial structure of the plasma. The results show that the population density of the neutral neon in this metastable state is found to be in the range of 1016 m−3, and that its spatial distribution is associated with the 3D structure of the magnetic field. We also report that the spatial distribution strongly varies with the mode structure, which depends on the microwave power.
Carbon nanotube bolometers
Authors: Tarasov M. , Svensson J. , Kuzmin L. , Campbell E. E. B.
Published: April 2007

A cryogenic bolometer has been fabricated using a bundle of single-walled carbon nanotubes as absorber. A bolometric response was observed when the device was exposed to radiation at 110GHz. The temperature response was 0.4mV∕K, with an intrinsic electrical responsivity at low frequency up to 109V∕W and noise equivalent power of 3×10−16W∕Hz1∕2 at 4.2K. The response is largest at input power levels of a few femtowatts and decreases inversely proportional to the input power. Low frequency noise shows a 1∕f dependence.
White light generation under violet-blue excitation from tunable green-to-red emitting Ca2MgSi2O7:Eu,Mn through energy transfer
Authors: Chang Chun-Kuei , Chen Teng-Ming
Published: April 2007

Yellowish green-to-orange red emission can be generated by energy transfer from Eu2+ to Mn2+ in the Ca2MgSi2O7 host matrix. Eu2+-doped Ca2MgSi2O7 shows a broad green emission band centering at 528nm and Mn2+-doped Ca2MgSi2O7 exhibits a red emission at around 602nm. The authors have demonstrated that the mechanism of energy transfer from Eu2+ to Mn2+ in Ca2MgSi2O7:Eu,Mn phosphor is a resonant type via a dipole-quadrupole mechanism. They have also shown that the white light with varied hue, depending on contents of Mn2+, is generated by combination of predesigned emission wavelength-tunable Ca2MgSi2O7:Eu,Mn phosphors and violet-blue light source.
Single-dopant organic white electrophosphorescent diodes with very high efficiency and its reduced current density roll-off
Authors: Cocchi M. , Kalinowski J. , Virgili D. , Fattori V. , Develay S. , Williams J. A. G.
Published: April 2007

Very high-efficiency organic white light electrophosphorescent diodes (WLEDs) have been fabricated using an efficient N∧C∧N-coordinated platinum (II) complex phosphor dopant. Their white light emanation is underlain by the simultaneous emission of monomer in blue and excimer in red. By optimizing the phosphor concentration and confining the electron-hole recombination zone to the emitter layer in the devices, the authors achieve their unusually high forward viewing external quantum efficiency (QE) up to 15.5±0.2% and 13.0±0.2% photons/electron at low and high drive current densities, corresponding to 40 and 1300cd∕m2, respectively. The current density where QE drops by half of its peak value is greater than three times that of the highest efficiency single-dopant WLEDs reported hitherto. The performance parameters of the presented devices can be further improved by using efficient dopants with the emission spectrum shifted towards blue.
High Q modes in elliptical microcavity pillars
Authors: Whittaker D. M. , Guimaraes P. S. S. , Sanvitto D. , Vinck H. , Lam S. , Daraei A. , Timpson J. A. , Fox A. M. , Skolnick M. S. , Ho Y.-L. D. , Rarity J. G. , Hopkinson M. , Tahraoui A.
Published: April 2007

The degenerate fundamental mode of a microcavity pillar structure with circular cross section splits into two linearly polarized modes when the shape is changed to elliptical. The quality factor Q of these modes is very different. This letter demonstrates that the high Q mode provides better values of the figure of merit for strong coupling applications, Q∕V), where V is the modal volume, compared to values obtainable in circular structures. The difference in Q is shown to be a consequence of the polarization dependence of the losses through the microcavity mirrors.
Ultrasensitive gas sensitivity property of BaMnO3 nanorods
Authors: Wang N. , Hu C. G. , Xia C. H. , Feng B. , Zhang Z. W. , Xi Y. , Xiong Y. F.
Published: April 2007

Perovskite manganite BaMnO3 nanorods have been synthesized by using a composite- hydroxide-mediated method. Gas sensitivity has been investigated on the BaMnO3 nanorods under different concentrations of O2 and different temperatures. The temperature dependent conductance of the BaMnO3 nanorod in O2 atmosphere indicates a n-type semiconductive property. Ultrasensitivity to O2 has been obtained at lower working temperatures, and distinctive sensitivity at different working temperatures is observed. These results highlight that the nanorods might be adopted for development of gas sensors with performances suitable for practical applications.
Complex impedance measurements of calorimeters and bolometers: Correction for stray impedances
Authors: Lindeman Mark. A. , Barger Kathleen A. , Brandl Donald E. , Crowder S. Gwynne , Rocks Lindsay , McCammon Dan
Published: April 2007

Impedance measurements provide a useful probe of the physics of bolometers and calorimeters. We describe a method for measuring the complex impedance of these devices. In previous work, stray impedances and readout electronics of the measurement apparatus have resulted in artifacts in the impedance data. The technique allows experimenters to find an independent Thevenin or Norton equivalent circuit for each frequency. This method allows experimenters to easily isolate the device impedance from the effects of parasitic impedances and frequency dependent gains in amplifiers.
Nanostructuring induced enhancement of radiation hardness in GaN epilayers
Authors: Ursaki V. V. , Tiginyanu I. M. , Volciuc O. , Popa V. , Skuratov V. A. , Morkoç H.
Published: April 2007

The radiation hardness of as-grown and electrochemically nanostructured GaN epilayers against heavy ion irradiation was studied by means of photoluminescence (PL) and resonant Raman scattering (RRS) spectroscopy. A nanostructuring induced enhancement of the GaN radiation hardness by more than one order of magnitude was derived from the PL and RRS analyses. These findings show that electrochemical nanostructuring of GaN layers is a potentially attractive technology for the development of radiation hard devices.
Comparative study of the influence of LiF, NaF, and KF on the performance of polymer bulk heterojunction solar cells
Authors: Ahlswede Erik , Hanisch Jonas , Powalla Michael
Published: April 2007

Based on the well-known beneficial effect of a thin LiF layer underneath Al contacts for organic solar cells, a comparative study of interlayers made from the alkaline fluorides LiF, NaF, and KF is presented for polymer bulk heterojunction solar cells. The overall suitability of these materials and the underlying mechanisms are discussed. While an improvement in cell efficiency up to a factor of 2 can be reached with all three fluorides, the necessary thickness of the interlayer for maximum improvement is smallest for NaF and largest for LiF, suggesting the alternative use of NaF instead of LiF.
Isotope quantum effects in the electron momentum density of water
Authors: Nygård K. , Hakala M. , Pylkkänen T. , Manninen S. , Buslaps T. , Itou M. , Andrejczuk A. , Sakurai Y. , Odelius M. , Hämäläinen K.
Published: April 2007

The isotope quantum effects in the ground-state electron momentum density of water are studied at temperatures ranging from 5to90°C by combining Compton scattering experiments utilizing synchrotron radiation and computational analysis within density functional theory. We observe clear differences in the momentum density between normal and heavy water at room temperature, which are interpreted as predominantly reflecting intramolecular structural differences. The changes in the momentum density upon increasing the temperature are found to be larger for heavy than for normal water, which is attributed primarily to temperature-induced intramolecular structural effects. Both model computations and an ab initio approach qualitatively reproduce the changes in the momentum density as a function of temperature.
Fabrication and characterization of PbS/multiwalled carbon nanotube heterostructures
Authors: Yu Dingshan , Chen Yujie , Li Baojun , Chen Xudong , Zhang Mingqiu
Published: April 2007

PbS quantum dots/multiwalled carbon nanotube (PbS/MWCNT) heterostructures were fabricated via a simple wet-chemical method. The structural and optical properties of as-prepared samples were characterized by transmission electron microscopy, x-ray diffraction, micro-Raman, and photoluminescence spectroscopies. It was found that the size, shape, and coverage density of the PbS quantum dots on the MWCNT can be controlled through varying synthesis conditions. Photoluminescence spectrum revealed that the emission of the PbS quantum dots was partially quenched when they were coupled to the MWCNT. This suggests that the photoinduced charge transfer may occur between the PbS and the MWCNT.
Crystallinity and surface effects on Young’s modulus of CuO nanowires
Authors: Tan E. P. S. , Zhu Y. , Yu T. , Dai L. , Sow C. H. , Tan V. B. C. , Lim C. T.
Published: April 2007

The authors investigate the crystallinity and surface effects on Young’s modulus of cupric oxide (CuO) nanowires by performing three-point bend test using atomic force microscopy. Young’s modulus of the nanowires obtained ranges from 70to300GPa and is dependent on two factors. Firstly, it depends on whether the nanowire is mono- or polycrystalline, as indicated by the absence or presence of an amorphous surface layer. Second, the modulus increases with decreasing diameter for both types of nanowires. Combined with transmission electron microscopy and computational simulation studies, the nanostructure-mechanical property relationship of CuO nanowires is elucidated.
Escherichia coli identification and strain discrimination using nanosecond laser-induced breakdown spectroscopy
Authors: Diedrich Jonathan , Rehse Steven J. , Palchaudhuri Sunil
Published: April 2007

Three strains of Escherichia coli, one strain of environmental mold, and one strain of Candida albicans yeast have been analyzed by laser-induced breakdown spectroscopy using nanosecond laser pulses. All microorganisms were analyzed while still alive and with no sample preparation. Nineteen atomic and ionic emission lines have been identified in the spectrum, which is dominated by calcium, magnesium, and sodium. A discriminant function analysis has been used to discriminate between the biotypes and E. coli strains. This analysis showed efficient discrimination between laser-induced breakdown spectroscopy spectra from different strains of a single bacteria species.
Controllable shrinking and shaping of silicon nitride nanopores under electron irradiation
Authors: Zhang W. M. , Wang Y. G. , Li J. , Xue J. M. , Ji H. , Ouyang Q. , Xu J. , Zhang Y.
Published: April 2007

Modification of silicon nitride nanopores under electron beam (e-beam) irradiation was investigated using a scanning electron microscope (SEM). Under e-beam irradiation, all pores with diameters ranging from 40to200nm undergo shrinkage, and the shrinkage rate increases with the rate of energy deposition. By using the selected-area scanning tool in the SEM, the silicon nitride nanopores can be selectively reshaped based on localized e-beam irradiation, with a characteristic dimension smaller than 10nm. A selected-area shaping technique was proposed to controllably shrink and shape the nanopores to a special structure.
Model of a low-permittivity and high-tunability ferroelectric based composite
Authors: Sherman Vladimir O. , Tagantsev Alexander K. , Setter Nava
Published: April 2007

It is shown that a prominent feature of ferroelectric-dielectric composites—the possibility of reducing their permittivity while keeping their tunability—may be substantially enhanced when using a ferroelectric matrix with “flatten” dielectric inclusions (inclusions with one dimension much smaller than two others). The composite containing flat inclusions oriented normal to the applied electric field is expected to yield a dielectric performance similar to that of the composite with nonflatten inclusions, albeit at much smaller concentrations of the dielectric. This effect is demonstrated from small-signal dielectric nonlinearity in diluted composite with spheroidal dielectric inclusions. It is proposed to use the composites of the considered structure in microwave systems in which low-permittivity tunable materials are required.
Optical modes in pyramidal GaAs microcavities
Authors: Weber F. M. , Karl M. , Lupaca-Schomber J. , Löffler W. , Li S. , Passow T. , Hawecker J. , Gerthsen D. , Kalt H. , Hetterich M.
Published: April 2007

Pyramidal GaAs structures on top of GaAs∕AlAs distributed Bragg reflectors are investigated as candidates for true three-dimensional cavities with potentially low mode volume and high quality-factor. Different types of single and coupled resonators with base lengths of a few microns are realized using a combination of molecular-beam epitaxy, electron-beam lithography, and wet chemical etching. Embedded InGaAs quantum dots are utilized as light sources to verify the resonator modes. Furthermore, a spatially localized emission through the pyramid facets indicates the future possibility of coupling cavity modes to optical fibers. This could be interesting within the context of single photon emitters.
Interfacing an aspiration ion mobility spectrometer to a triple quadrupole mass spectrometer
Authors: Adamov Alexey , Viidanoja Jyrki , Kärpänoja Esko , Paakkanen Heikki , Ketola Raimo A. , Kostiainen Risto , Sysoev Alexey , Kotiaho Tapio
Published: April 2007

This article presents the combination of an aspiration-type ion mobility spectrometer with a mass spectrometer. The interface between the aspiration ion mobility spectrometer and the mass spectrometer was designed to allow for quick mounting of the aspiration ion mobility spectrometer onto a Sciex API-300 triple quadrupole mass spectrometer. The developed instrumentation is used for gathering fundamental information on aspiration ion mobility spectrometry. Performance of the instrument is demonstrated using 2,6-di-tert-butyl pyridine and dimethyl methylphosphonate.
Plasma rotation measurement in small tokamaks using an optical spectrometer and a single photomultiplier as detector
Authors: Severo J. H. F. , Nascimento I. C. , Kuznetov Yu. K. , Tsypin V. S. , Galvão R. M. O. , Tendler M.
Published: April 2007

The method for plasma rotation measurement in the tokamak TCABR is reported in this article. During a discharge, an optical spectrometer is used to scan sequentially spectral lines of plasma impurities and spectral lines of a calibration lamp. Knowing the scanning velocity of the diffraction grating of the spectrometer with adequate precision, the Doppler shifts of impurity lines are determined. The photomultiplier output voltage signals are recorded with adequate sampling rate. With this method the residual poloidal and toroidal plasma rotation velocities were determined, assuming that they are the same as those of the impurity ions. The results show reasonable agreement with the neoclassical theory and with results from similar tokamaks.
Design of multipulse Thomson scattering diagnostic for SST-1 tokamak
Authors: Kumar Ajai , Chavda Chhaya , Saxena Y. C. , Singh Ranjeet , Thakar Aruna , Thomas Jinto , Patel Kiran , Pandya Kaushal , Bedakihale Vijay
Published: April 2007

A multipulse Nd:YAG (Yttrium aluminum garnet) Thomson scattering (TS) system is designed and developed for measuring electron temperature (Te) and density (ne) profiles of SST-1 tokamak. The system operates at vertical, divertor, and horizontal (midplane) regions of plasma and measures the electron temperature of 20eVto1.5keV and density of 1018–1019m−3. Six Nd:YAG lasers synchronized with external control is used to get three different temporal resolutions (30Hz, 180Hz, and 1kHz). The entire system is laboratory tested for the stability of alignment and performance over a distance of 30m. Different imaging lens assemblies are designed to image the scattered photons from each of the scattering region to an array of optical fibers. A low cost and compact five-channel interference filter polychromator is designed, fabricated, and tested for its image quality and the filter transmission characteristics. Detection system with an avalanche photodiode and required signal conditioning electronics is developed for detecting the scattered photons. A data acquisition and control module operating on PXI bus is developed for the real time data acquisition and system control. A detailed description of design and testing of TS subsystems is presented in this article.
Cathodoluminescence spectroscopy and imaging of GaN∕(Al,Ga)N nanocolumns containing quantum disks
Authors: Jahn Uwe , Ristić Jelena , Calleja Enrique
Published: April 2007

Using spatially resolved cathodoluminescence spectroscopy, the authors have measured the spectral and spatial distribution of the luminescence intensity of GaN∕(Al,Ga)N nanocolumns containing quantum disks. The optical emission of the quantum disk and of the thick (Al,Ga)N layer in the columns were clearly identified. The disk spectra of single columns are as broad as 80meV. A significant contribution to this broadening is probably due to the laterally inhomogeneous strain distribution within the disks. The optical emission of the thick (Al,Ga)N layer in the columns is spread out over a wide spectral range of several 100meV, which is caused by an inhomogeneous incorporation of Al along the growth direction of the columns.
Stability of simple cubic crystals
Authors: Djohari Hadrian , Milstein Frederick , Maroudas Dimitrios
Published: April 2007

Although simple cubic (sc) crystals tend to be “inherently unstable” under ambient conditions, their potential stability is enhanced in states of pure hydrostatic tension, which can be approached locally near stress raisers such as cracks. Our molecular-dynamics simulations verify that a range of hydrostatic stress exists under which sc crystals are stable. Three distinct destabilization mechanisms are observed, depending on the bulk-modulus magnitude and the magnitude and algebraic sign of the shear modulus μ′, which in turn depend on the stress level; two of these mechanisms result in fracture, while the third yields a sc-to-hcp phase transformation by a unique two-stage shearing process.
All-optical bistable switching in curved microfiber-coupled photonic crystal resonators
Authors: Kim Myung-Ki , Hwang In-Kag , Kim Se-Heon , Chang Hyun-Joo , Lee Yong-Hee
Published: April 2007

The authors report low-power optical bistability under continuous wave pumping conditions in five-cell photonic crystal linear resonators containing InGaAsP quantum wells, by employing the fiber-coupling technique. The threshold bistable power is measured to be 35μW at the normalized detuning of −1.724. Owing to the high band-edge nonlinearities of quantum wells and the efficient fiber coupling, minimal instability is observed. In addition, all-optical switching is demonstrated with switching energy less than 75.4fJ.
New mixing system in dissolution isoperibol microcalorimeter
Authors: Moreno-Piraján Juan Carlos , Giraldo-Gutierréz Liliana
Published: April 2007

In order to determine dissolution enthalpies of small amounts of easily or slightly soluble solids, a new cell for batch isoperibolic microcalorimetry was developed at the Universities of the Andes and the National of Colombia. An innovative mixing system for avoiding error due to the common effect of the brittle point breakage has been designed for this cell. The cell has a capacity of 40ml and the sample holder can bear solid samples between 10.0 and 30.0mg. The high stability of the base line allows solution experiments to be extended over several hours. All measurements reported were conducted at 298.15K using water as solvent.
Diffused phase transition and relaxor behavior in Pb(Fe2∕3W1∕3)O3 thin films
Authors: Kumar Ashok , Murari N. M. , Katiyar R. S.
Published: April 2007

The authors have synthesized Pb(Fe2∕3W1∕3)O3 thin films on Pt∕Ti∕SiO2∕Si(100) substrates utilizing chemical solution deposition method. The dielectric relaxation was studied as a function of temperature (100–300K) and frequency (100Hz–1MHz). A broad range of dielectric maxima was found, which shifted towards higher temperature with increase in frequency. The relaxation indication coefficient (γ) and broadening parameter (Δ) were estimated from a linear fit of the modified Curie-Weiss law and were found to be 2.00 and 50K, respectively; indicating strong relaxor behavior. A remarkably good fit to Vogel-Fulcher relationship further supports the relaxor nature of the films. The slim hysteresis loop at low temperature is indicative of ferroelectricity due to the growth of nanopolar regions.
Interaction of an infrared surface plasmon with an excited molecular vibration
Authors: Rodriguez Kenneth R. , Tian Hong , Heer Joseph M. , Teeters-Kennedy Shannon , Coe James V.
Published: April 2007

The interaction of an infrared surface plasmon and an excited molecular vibration was investigated by using a square array of subwavelength holes in a Ni film which supports propagating, surface-plasmon-mediated, transmission resonances. The largest transmission resonance [the (1,0)−] was tuned through the rocking vibration of the hexadecane molecule (at 721cm−1) in a hexadecane film on the mesh by varying the thickness of the film. The interaction of the rocking vibration and surface plasmon is characterized spectroscopically by an increase in the intensity of the vibrational band by more than a factor of 2, variation of the vibrational line shape relative to the spectrum on a nonmetallic surface, and shifts in vibrational peak position by as much as 3.0cm−1. Relationships are developed between the transmission resonance position and the thickness and dielectric properties of the coating.
The Rac1 guanine nucleotide exchange factor Tiam1 mediates EphB receptor-dependent dendritic spine development
Authors: Tolias Kimberley F. , Bikoff Jay B. , Kane Christina G. , Tolias Christos S. , Hu Linda , Greenberg Michael E.
Published: April 2007

Dendritic spines are small, actin-rich protrusions on the surface of dendrites that receive the majority of excitatory synaptic inputs in the brain. The formation and remodeling of spines, processes that underlie synaptic development and plasticity, are regulated in part by Eph receptor tyrosine kinases. However, the mechanism by which Ephs regulate actin cytoskeletal remodeling necessary for spine development is not fully understood. Here, we report that the Rac1 guanine nucleotide exchange factor Tiam1 interacts with the EphB2 receptor in a kinase-dependent manner. Activation of EphBs by their ephrinB ligands induces the tyrosine phosphorylation and recruitment of Tiam1 to EphB complexes containing NMDA-type glutamate receptors. Either knockdown of Tiam1 protein by RNAi or inhibition of Tiam1 function with a dominant-negative Tiam1 mutant blocks dendritic spine formation induced by ephrinB1 stimulation. Taken together, these findings suggest that EphBs regulate spine development in part by recruiting, phosphorylating, and activating Tiam1. Tiam1 can then promote Rac1-dependent actin cytoskeletal remodeling required for dendritic spine morphogenesis.
Roman Egypt
Authors: Harmless William, S.J.
Published: April 2007

This chapter provides necessary background by examining the wider world from which the desert fathers and desert monasticism emerged. It concentrates on Roman Egypt, its geography, history, politics, and religious milieu. This survey includes a look at ancient Alexandria as well as at life along the Nile Valley. It also examines three features of early Egyptian Christianity: the Alexandrian theological tradition (best embodied by Origen), the Melitian schism, and the early Alexandrian patriarchate.
TheLife of Antony: Themes and Influence
Authors: Harmless William, S.J.
Published: April 2007

The Life of Antony’s folktale surface should not lead modern readers to underestimate its sophistication. Athanasius was not only a skilled literary artist, but also a gifted theologian and a prominent politician on the international scene. He brought his formidable theological talents and his partisan political biases to this work, using it as propaganda against Arian and Melitian opponents. This chapter examines three theological themes that wind their way through the text: Christ’s victory over the demons, Antony as an image of deification, and Antony as a model of orthodoxy. At the close, it explores the Life of Antony’s long-term literary influence on lives of the saints and its historical influence on the conversion of Augustine of Hippo.
The Apophthegmata Patrum: Text and Context
Authors: Harmless William, S.J.
Published: April 2007

The Apophthegmata Patrum (Sayings of the Fathers) is a collection of more than 1,000 brief stories about and sayings by the desert fathers. Some are terse aphorisms, others portray dramatic encounters in which young monks come to their elders, begging: “Abba, give me a word by which I might be saved.” This collection, dating from the late fifth or early sixth century, is the best known and most influential work of desert Christian literature and has been preserved in a variety of ancient languages and editions. This chapter provides an introduction to the Apophthegmata’s literary style and its historical setting—especially its roots in the ancient monastery of Scetis.
The Histories
Authors: Harmless William, S.J.
Published: April 2007

This chapter examines two early and influential historical narratives. The first, Palladius’s Lausiac History (Historia Lausica), is a set of brief biographies and vignettes of the desert fathers (and mothers), written in Greek in the 420s. The other, the anonymous History of the Monks in Egypt (Historia monachorum in Aegypto), is a travelogue, composed in Greek about 400. It describes a journey through Egypt taken by seven Palestinian monks in 394 and strings together anecdotes about their meetings with remarkable hermits, healers, and holy men. These works highlight other important monastic sites, especially Nitria and Kellia, and stress the links between miracles and holiness.
Evagrius Ponticus: Mystical Theology
Authors: Harmless William, S.J.
Published: April 2007

Evagrius Ponticus was one of the great pioneers of Christian mystical theology. He spoke of prayer as “the ascent of the mind to God” and argued that “pure prayer” must be unceasing, imageless, and wordless. At the peak of the mystical journey, the monk encounters what Evagrius called the “sapphire light of the mind,” both an interior illumination and a glimpse of the uncreated light of the Trinity. This chapter sets out both Evagrius’s map of the mystical journey to God and the controversy that it provoked after his death, the so-called Origenist Controversy.
The Science and Technology System
Authors: Miozzo Marcela , Walsh Vivien
Published: April 2007

This chapter considers the main source of innovation: research and development (R&D) activity. It examines where the inventions and innovations come from in terms of the countries that specialize in their production, the institutions carrying out R&D, and the institutions which provide the sources of the relevant R&D funding. It examines the evolution of science and technology, from an activity carried out by few people with a private income or an activity sponsored by patrons, to its professionalization and the rise of the in-house corporate R&D laboratory. The amount and nature of government-funded R&D, defence-related R&D, and industrial R&D in different countries are studied.
Organizations and Technology during the Periods of ‘New Competition’ and ‘Systems Integration’
Authors: Miozzo Marcela , Walsh Vivien
Published: April 2007

This chapter describes the new forms of business and production organization in Japan and the ‘third Italy’ (new competition), which exposed the limitations in production organization of managerial capitalism. These forms include ‘networks’ of firms (in the shape of large corporations in Japan and small firm industrial districts in Italy), inter-firm relations, new production concepts such as just-in-time, and the role of industrial policy. The problems of this form of business and production organization are described. The business and production organization forms responsible for the resurgence of US high-tech industry (network-based systems integration) are examined.
Organizations, Technology, and Less Developed Countries: East Asia and Latin America
Authors: Miozzo Marcela , Walsh Vivien
Published: April 2007

This chapter examines how East Asian countries became industrialized, and explores the contrast between industrialization in East Asia and Latin America since the 1970s. The chapter is organized as follows. The first section examines the debates on industrialization in the 19th century and draws lessons for industrialization in the 20th century. The second section addresses how East Asian countries caught up with the more advanced countries. The third section compares organizations and technology in Latin America and East Asia which are responsible for Latin American countries falling behind. The conclusion draws lessons for the understanding of the relation between organizations, technology, and less developed countries.
Globalization of Trade, Production, and Technology
Authors: Miozzo Marcela , Walsh Vivien
Published: April 2007

This chapter examines the meaning of globalization and the debates surrounding the concept. The effects of globalization on the international division of labour and the integration of strategy and management within multinationals are explored. The implications of globalization for national governments and for innovation are considered. The evidence regarding the globalization of innovative activity is assessed.
Osseointegration Timing for Baha System Loading
Authors: Wazen Jack J. , Gupta Reena , Ghossaini Soha , Spitzer Jaclyn , Farrugia Matthew , Tjellstrom Anders
Published: April 2007

Objectives: The process of osseointegration for creating a biological bond between titanium oxide and bone is time dependent. However, different surgeons have used very varied time frames before loading the implant. The waiting time in dental implant loading ranged from immediate to 6 months. The Baha system (Cochlear Limited, Englewood, CO) traditional waiting period consisted of 3 months for adults and 4 to 6 months for children. The purpose of the study was to evaluate the safety of reducing the waiting time to 6 weeks in adults.

Study Design: Retrospective study of patients who underwent Baha implantation and exteriorization between March, 2004 and July 2005.

Methods: Twenty‐six adult patients underwent Baha titanium implantation and exteriorization in a single stage. They were loaded with the external processor after an average of 6.5 weeks. The etiology of their hearing loss (HL) included conductive HL, mixed HL, and unilateral sensorineural HL. Follow‐up period ranged between 6 and 20 months.

Results: All patients were successfully implanted with the titanium implants, loaded at the 6 week interval, and have safely retained their prosthesis. The only reported complication was dermatitis, which occurred in three patients. Patients were pleased to receive the external processor earlier.

Conclusion: The reduction of the waiting period from 3 months to 6 weeks did not result in any failure of osseointegration of the titanium implants. The earlier activation resulted in enhanced patient satisfaction. A larger series would be needed to definitively recommend shortening of the interval between Baha implantation and device loading.
Restorative Rhinoplasty in the Aging Patient
Authors: Cochran C Spencer , Ducic Yadranko , DeFatta Robert J.
Published: April 2007

Objective: The objective of this study is to review our favorable experience in performing rhinoplasty in aging patients.

Methods: All patients aged 65 years or greater who underwent rhinoplasty, either esthetic or functional, by the senior author (Y.D.) from August 1997 to July 2005 with a minimum follow up of 1 year were retrospectively reviewed.

Results: A total of 51 patients met the inclusion criteria and had complete records available for review. The average age was 69.5 years (range, 65–82 years) with 24 female and 27 male patients. All but two patients underwent open rhinoplasty. Eighteen procedures represented secondary rhinoplasties. Seven patients required auricular cartilage grafts, and 11 patients required costal cartilage grafts. One costal cartilage graft was aborted as a result of excessive calcification. All patients underwent columellar strut placement, 92% underwent internal valve grafts, and 80.4% underwent grafting of the external nasal valves. Nasal osteotomies were performed in only 23.5% of patients, all with the percutaneous technique. Revision surgery was necessary in only three (5.8%) patients, all of whom required grafting of the external valve (not performed primarily). In each of these cases, no significant external valve collapse was noted preoperatively. Premaxillary augmentation with diced or crushed cartilage grafts was performed in 81.8% (n = 18) of patients with an edentulous maxillary arch.

Conclusions: Aging patients present unique technical challenges in rhinoplasty that warrant a comprehensive approach to restore internal and external valve competency and tip support. Consideration of prophylactic external valve grafts in addition to the routine use of internal valve grafts and columellar struts may help decrease the need for revision surgery in this patient population. Reasonable functional and esthetic outcomes can be expected in the aging patient.
Signaling by Way of Type IB and II Bone Morphogenetic Protein Receptors Regulates Bone Formation in Otospongiosis
Authors: Lehnerdt Goetz , Metz Klaus Alfred , Trellakis Sokratis , Jahnke Klaus , Neumann Andreas
Published: April 2007

Hypothesis: The main goal of this study was to perform an immunohistologic analysis of bone morphogenetic protein receptors (BMPR) in otospongiosis.

Background. BMP‐2, ‐4, and ‐7 play an essential role in bone formation and repair. They do so as well in otosclerosis. It has been shown that these BMPs are traceable in osteocytes and osteoclasts in the active phase of otosclerosis (otospongiosis). The role of the different BMP receptors in otosclerotic bone transformation has not been previously analyzed.

Methods: The posterior parts of the stapes footplates, collected during partial stapedectomies in 35 patients with clinical otosclerosis, were analyzed for histologic otosclerotic lesions after hematoxylin staining. Immunohistochemical analysis was performed using polyclonal immunoglobulin G antibodies for BMPR‐IA, ‐IB, and ‐II, as well as biotinylated secondary antibodies, avidin‐biotin‐peroxidase complex reaction, and alkaline phosphatase staining with nitroblue‐tetrazolium‐chloride.

Results: Seventeen of 35 (49%) specimens contained otosclerosis, but only 5 of these exhibited an otospongiotic phase. The abundant osteoblasts and osteoclasts in these cases showed distinct immunochemical staining for BMP‐2, ‐4, and ‐7. In two cases, there could also be found an immense positive staining for BMPR‐IB and modest staining for BMPR‐II, whereas BMPR‐1A always remained negative.

Conclusion: It was demonstrated for the first time that in otospongiosis, the actions of the BMPs are mediated through BMPR‐IB and BMPR‐II. To determine this role in detail, further investigations, especially for the phosphorylated Smad proteins within the BMP dependent mediator cascade, will be necessary.
Free Tissue Transfer to Manage Salvage Laryngectomy Defects After Organ Preservation Failure
Authors: Withrow Kirk P. , Rosenthal Eben L. , Gourin Christine G. , Peters Glenn E. , Magnuson J Scott , Terris David J. , Carroll William W.
Published: April 2007

Objective: Salvage laryngectomy to treat organ preservation failures results in significantly higher local wound complications. Even in the absence of extralaryngeal disease, primary closure of laryngeal defects can result in protracted wound care problems. We hypothesize that even when sufficient mucosa is present to close the defect primarily, introduction of vascularized tissue to close the defect may improve outcomes.

Design: Retrospective case‐control study.

Setting: Two academic tertiary care centers.

Patients and Methods: Patients undergoing salvage surgery for laryngeal squamous cell carcinoma between 2000 to 2006 were considered for this study. Patients requiring total laryngopharyngectomy or partial pharyngectomy were excluded. There were 37 patients who met study criteria: 17 patients underwent free flap reconstruction (16 radial forearm flaps and 1 rectus flap), and 20 patients underwent primary closure. The median follow‐up was 12 (range, 4–60) months. Previous treatment consisted of chemoradiation for 41% of the reconstruction group and 35% of the primary closure group; the remainder were treated with primary radiation alone.

Main Outcome Measures: Pharyngocutaneous fistula, stricture, length of hospitalization, feeding tube dependence.

Results: The free flap reconstruction group had a lower rate of fistula (18%) compared with the primary closure group (50%). A lower rate of stricture formation (18% vs. 25%) and feeding tube dependence (23% vs. 45%) was observed in the free flap reconstruction group compared with the primary closure group. The development of a fistula in either group resulted in a prolonged hospital stay (mean, 19 vs. 7 days) and additional procedures.

Conclusion: Planned reconstruction of salvage laryngectomy defects with vascularized tissue is associated with a lower fistula rate and may improve outcomes.
Impact of Aspirin Intolerance on Outcomes of Sinus Surgery
Authors: Robinson Jamie L. , Griest Susan , James Kenneth E. , Smith Timothy L.
Published: April 2007

Objectives: To compare objective and quality of life (QOL) outcomes after endoscopic sinus surgery (ESS) in aspirin (ASA)‐tolerant patients and ASA‐intolerant patients over intermediate and long‐term follow‐up.

Study Design: Prospective analysis of a cohort of patients with chronic rhinosinusitis.

Methods: Preoperative computed tomography (CT), pre‐ and postoperative endoscopy, and two validated disease specific QOL instruments, the Rhinosinusitis Disability Index (RSDI) and Chronic Sinusitis Survey (CSS), were collected. Differences in the proportions of patients who improved were analyzed using Pearson's chi‐square and Fisher's exact test.

Results: Nineteen ASA‐intolerant patients and 104 ASA‐tolerant patients were followed for a mean of 17.7 months. Patients with ASA intolerance had significantly worse preoperative CT (P < .0001) and endoscopy scores (P < .0001). After ESS, 57% to 74% of patients improved on endoscopy scores, 63% to 71% improved on the RSDI, and 58% to 73% improved on the CSS; improvement did not significantly differ by ASA status.

Conclusions: Similar proportions of ASA‐tolerant and ASA‐intolerant patients showed improvement on endoscopy and QOL measures after ESS.
Pseudomonas aeruginosa Lipopolysaccharide Induces Osteoclastogenesis Through a Toll‐Like Receptor 4 Mediated Pathway in Vitro and in Vivo
Authors: Zhuang Lei , Jung Jae Y. , Wang Eric W. , Houlihan Patrick , Ramos Lisette , Pashia Mary , Chole Richard A.
Published: April 2007

Objectives: Bacterial infections near bone result in localized inflammatory osteolysis, a significant complication of chronic ear infections. While many bacterial products may be involved, lipopolysaccharide (LPS) has been implicated as a major mediator of inflammation and osteolysis. However, the mechanisms by which LPS promotes bone resorption have not been clearly established. There is no consensus on whether LPS acts directly or indirectly on osteoclast precursors (bone marrow monocytes [BMM]) to induce bone resorption. In light of the role of Pseudomonas aeruginosa, in chronic ear infections, we investigated the effects of P. aeruginosa LPS on osteoclastogenesis in vivo and in vitro.

Methods: Wild‐type C57BL/6J and toll‐like receptor 4 knock‐out (TLR4−/−) mice received subcutaneous calvarial injections of 250 μg of P. aeruginosa LPS or phosphate buffered saline (PBS) only (n = 5 per group). Osteoclastic bone resorption was assessed histologically. The effect of P. aeruginosa LPS on bone resorption was assessed in vitro using combinations of BMMs and osteoblasts with and without functional toll‐like receptor 4 (TLR4).

Results: In vivo, P. aeruginosa LPS induced robust osteolysis, and this effect was completely abrogated in mice lacking expression of TLR4. In vitro, P. aeruginosa LPS failed to induce development of osteoclasts directly in BMMs. However, P. aeruginosa LPS did stimulate osteoclastogenesis in BMM‐osteoblast cocultures.

Conclusions: P. aeruginosa LPS acts indirectly through osteoblasts to induce bone resorption. Optimal osteoclastogenesis in vitro required functional TLR4 expression in both BMMs and osteoblasts.
Surgical Outcomes Following the Endoscopic Modified Lothrop Procedure
Authors: Shirazi Mobeen A. , Silver Amanda L. , Stankiewicz James A.
Published: April 2007

Objective: We performed a systematic review of 97 patients in whom an entirely endoscopic modified Lothrop procedure (EMLP) was performed. We studied the safety, efficacy, need for revision surgery, and rate of complication following an EMLP.

Study Design: The study design was a retrospective chart analysis.

Methods: We performed a retrospective chart review and patient survey of 97 patients who underwent an EMLP at our institution from January 1999 to March 2006. Main outcomes measured were the need for revision surgery including an osteoplastic flap (OPF), improvement in patients' symptoms, and rate of cerebrospinal fluid (CSF) leak.

Results: The most common indication for the procedure was chronic frontal sinusitis and/or formation of mucocele. The frontal recess and floor of the frontal sinus were the most common areas of persistent disease. CSF leak rate was 1% (1/97) and was managed successfully at the time of surgery without any long‐term sequelae. Twenty‐two (23%) patients required revision surgery. Three (3%) patients required revision with an OPF. Some degree of symptomatic clinical improvement was reported by 98% (95/97) of patients.

Conclusion: EMLP is a safe and effective surgical alternative to OPF for patients with recalcitrant frontal sinus disease. Major complications are rare. A large percentage of patients may require revision surgery.