bluuebunny/crossref_metadata_2025 huggingface dataset:
Capacitance-voltage studies on enhancement-mode InGaAs metal-oxide-semiconductor field-effect transistor using atomic-layer-deposited Al2O3 gate dielectric
Authors: Xuan Y. , Lin H. C. , Ye P. D. , Wilk G. D.
Published: August 2006

Atomic layer deposition (ALD) Al2O3 is a high-quality gate dielectric on III-V compound semiconductor with low defect density, low gate leakage, and high thermal stability. The high-quality of Al2O3∕InGaAs interface surviving from high temperature annealing is verified by excellent capacitance-voltage (CV) curves showing sharp transition from depletion to accumulation with “zero” hysteresis, 1% frequency dispersion per decade at accumulation capacitance, and strong inversion at split CV measurement. An enhancement-mode n-channel InGaAs metal-oxide-semiconductor field-effect-transistor is also demonstrated by forming true inversion channel at Al2O3∕InGaAs interface.
Tailored emission color synthesis using microfacet quantum wells consisting of nitride semiconductors without phosphors
Authors: Funato M. , Kotani T. , Kondou T. , Kawakami Y. , Narukawa Y. , Mukai T.
Published: August 2006

A color synthesis based on InGaN∕GaN quantum wells (QWs) grown on GaN microfacets formed by regrowth on SiO2 mask stripes is demonstrated. The microfacet structure is composed of (0001), {112¯2}, and {112¯0} planes, and the InGaN well thickness and composition are spatially inhomogeneous due to the diffusion of the adatoms among the facets. These properties allow microfacet QWs, which, for example, emit yellow from the (0001) facet and blue from the {112¯2} facet, to be fabricated, of which the luminescence appears white due to the additive color mixing. Using a mask pattern that consists of regions with and without stripes, the emissions from the microfacet QWs and from planar QWs are synthesized to produce the desired apparent output colors.
Comparison between four-level model and six-temperature model on the description of a simple mechanical Q-switched CO2 laser
Authors: Wang Tie-Jun , He Qiong-Yi , Gao Jin-Yue , Sun Han , Kang Zhi-Hui , Jiang Yun , Zhang Ying-Fei
Published: August 2006

We investigate both the four-level model and the six-temperature model to describe the dynamical processes of a simple mechanical Q-switched CO2 laser that is realized by a fast chopper. The Q-switched process and the effect of the dynamic parameters on the output intensity of the Q-switched CO2 laser are reported using the two models. Theoretical comparisons between the two models on the effect of dynamical parameters, and the experimental results are presented. Both the models are well consistent with the experimental one for the main output laser pulse.
Structures and physical properties of LaxCa4−xMn3O10 (x=0,0.1) synthesized under high pressure
Authors: Yao L. D. , Yang H. , Zhang W. , Li F. Y. , Jin C. Q. , Yu R. C.
Published: August 2006

The nominal composition compounds LaxCa4−xMn3O10, (x=0,0.1) were synthesized using solid-state reaction under high pressure. The structures of the two samples have been studied by x-ray powder diffraction, transmission electron microscopy, and high-resolution electron microscopy. In the case of the nominal composition La0.1Ca3.9Mn3O10, besides the phase with n=2 member of Ruddlesden-Popper (RP) series, the phase with the ideal n=3 member RP structure (space group I4∕mmm) was formed. Moreover, it is interesting that some intergrowth or modulation structures were observed in some areas of n=3 phase. Based on the analysis of magnetic and electrical properties, LaxCa4−xMn3O10 undergoes from a paramagnetic-antiferromagnetic transition (x=0) at 104K to paramagnetic-weak ferromagnetic transition (x=0.1) at 113K ascribed to existence of La doped n=3 phase LaxCa4−xMn3O10 and intergrowth or modulation structures. Similar conductive mechanism, two-dimensional variable range hopping, is shown above magnetic transition temperatures for both samples. Compared to the very weak magnetoresistance in Ca4Mn3O10, the nominal composition La0.1Ca3.9Mn3O10 represents a 65% drop in resistivity in a magnetic field of 5T at 5K.
The Gell-Mann-Okubo and Coleman-Glashow relations for octet and decuplet baryons in the SUq(3) quantum algebra
Authors: Cárcamo Hernández Antonio E.
Published: August 2006

The q-deformed Clebsch-Gordan coefficients corresponding to the {3}×{21} reduction of the SUq(3) quantum algebra are computed. From these results and using the quantum Clebsch-Gordan coefficients for the {21}×{21} reduction found by Z. Q. Ma, the q-deformed Gell-Mann-Okubo mass relations for octet and decuplet baryons are determined by generalizing the procedure used for the SU(3) algebra. We also determine the Coleman-Glashow relations for octet and decuplet baryons in the SUq(3) algebra. Finally, by using the experimental particle masses of the octet and decuplet baryons, two values of the q-parameter are found and adjusted for the predicted expressions of the masses (one for the Gell-Mann-Okubo mass relations and the other for the Coleman-Glashow relations) and a possible physical interpretation is given.
Hydrogen plasma dry etching method for field emission application
Authors: Cheng T. C. , Shieh J. , Huang W. J. , Yang M. C. , Cheng M. H. , Lin H. M. , Chang M. N.
Published: August 2006

The ability to fabricate large-area, uniform emitters is an important factor in many vacuum microelectronics applications, especially for field emission displays. In this letter, we measured the field emission properties of uniform silicon nanowire emitters prepared by hydrogen plasma etching using in situ high-resolution scanning electron microscopy and a tungsten anode of 1μm diameter. Our results indicate that the field emission properties are improved upon increasing the etching time; this process sharpens the nanowires’ geometry and lowers their work function. These highly uniform (with respect to length, diameter, and distribution) nanowires display great potential for application within many field emission nanoelectronics devices.
Effect of barrier process on electromigration reliability of Cu/porous low-k interconnects
Authors: Pyun Jung Woo , Baek Won-Chong , Im Jay , Ho Paul S. , Smith Larry , Neuman Kyle , Pfeifer Klaus
Published: August 2006

Electromigration (EM) reliability of Cu/low-k interconnects with a conventional preclean-first process, and an advanced barrier-first process has been investigated. Compared with the preclean-first process, extrinsic early failures were not observed for the barrier-first process. This suggests that process-induced defects, which are the most probable cause for early failures, are significantly reduced for the barrier-first process. Transmission electron microscopy observation demonstrated a more uniform and thicker Ta barrier for the barrier-first process than the preclean-first process. This led to a higher (jL)c product, and prolonged the EM lifetime accordingly. In addition, a predeposited Ta barrier during the barrier-first process protected the mechanically weak low-k dielectrics from plasma etch damage, and a uniform via profile resulted. In contrast, the via opening at the top was found to be larger than that of at the via bottom for the preclean process. The uniform via profile is another advantage of the barrier-first process from the point of view of process control.
Probability distribution analysis of force induced unzipping of DNA
Authors: Kumar Sanjay , Giri Debaprasad
Published: August 2006

We present a semimicroscopic model of dsDNA by incorporating the directional nature of hydrogen bond to describe the force induced unzipping transition. Using exact enumeration technique, we obtain the force-temperature and the force-extension curves and compare our results with the other models of dsDNA. The model proposed by us is rich enough to describe the basic mechanism of dsDNA unzipping and predicts the existence of an “eye phase.” We show oscillations in the probability distribution function during unzipping. Effects of stacking energies on the melting profile have also been studied.
Study on the interface thermal stability of metal-oxide-semiconductor structures by inelastic electron tunneling spectroscopy
Authors: Huang Chih-Feng , Tsui Bing-Yue , Tzeng Pei-Jer , Lee Lurng-Shehng , Tsai Ming-Jinn
Published: August 2006

The bias polarity-dependent inelastic electron tunneling spectroscopy is employed to detect the thermal stability of the Ta–Pt∕SiO2∕Si and Ta–Pt∕HfO2∕Si structures. This work provides a direct evidence that the Fermi-level pinning of metal gates is counted for the generation of extrinsic states due to interface interaction. A Ta2O5 layer forms at the Ta–Pt∕SiO2 interface during thermal annealing whereas only an intermittent Ta–O bond is observed at the Ta–Pt∕HfO2 interface. Although the heat of formation of HfO2 is lower than that of SiO2, Si presumably diffuses into HfO2 layer and replaces Hf atoms during the high-temperature annealing.
Liquid crystals driven by CdSe semiconductor
Authors: Chu Kung-Ching , Su Wei-Sheng , Chen Yang-Fang
Published: August 2006

We report an approach of controlling liquid crystals using a laser beam without external bias. In our design, in addition to liquid crystals, a patterned semiconductor was also included. We discovered that the average pretilt angle of liquid crystals can be controlled by adjusting excitation power, and the relationship was found to follow the possible predicted photovoltaic effect. Besides, the photogenerated field was found to have both perpendicular and horizontal components, which is very useful to control the orientation of liquid crystals to an arbitrary direction. Optical switch devices can be possible to design using our method.
Dynamics of spectrally truncated inviscid turbulence
Authors: Bos W. J. T. , Bertoglio J.-P.
Published: August 2006

The evolution of the turbulent energy spectrum for the inviscid spectrally truncated Euler equations is studied by closure calculations. The observed behavior is similar to the one found in direct numerical simulations [Cichowlas, Bonaïtiti, Debbasch, and Brachet, Phys. Rev. Lett. 95, 264502 (2005)]. A Kolmogorov spectral range and an equipartition range are observed simultaneously. Between these two ranges a “quasi-dissipative” zone is present in the kinetic energy spectrum. The time evolution of the wave number that marks the beginning of the equipartition range is analyzed and it is shown that spectral nonlocal interactions are governing this evolution.
Equivalent circuit model for left-handed metamaterials
Authors: Chen Hongsheng , Ran Lixin , Huangfu Jiangtao , Grzegorczyk Tomasz M. , Kong Jin Au
Published: August 2006

A general equivalent circuit model to calculate the effective permeability of various configurations of split-ring resonators (SRRs) is presented. In the proposed model, each column of the SRR units along the axis of the rings is modeled as a quasisolenoid under magnetic induction. The inductance per ring of the infinite column of these rings is calculated, assuming all the rings in this column support the same current. The electromagnetic coupling between these individual columns of the rings is integrated into this circuit model, which is then applied to a two dimensional cross embedded split-ring resonator. The agreement between the predicted results and numerical simulations shows the efficiency of the model in predicting the frequency band of negative permeability.
Effect of the subwavelength hole symmetry on the enhanced optical transmission through metallic films
Authors: Sun Mei , Tian Jie , Han Shouzhen , Li Zhiyuan , Cheng Bingying , Zhang Daozhong , Jin Aizi , Yang Haifang
Published: August 2006

We present here the measurements on the extraordinary optical transmission when light passes through different subwavelength hole arrays fabricated on a 120-nm-thick gold film by the focused ion beam system. The comparison of optical transmission shows that the aperiodic concentric circular hole arrays, which possess the sixfold rotational symmetry and central-inversion symmetry, have higher transmittance (about six and two times larger in peak intensity, respectively) than the periodic hexagonal and square lattice of hole array structures. This phenomenon can be attributed to the stronger constructive interference of multiple scattered waves in a higher symmetrical hole array structure. In addition, although the three structures possess the same lattice constant 1μm and hole diameter 350nm, the enhanced transmission peak for the circular hole arrays locates in the visible region, while that of the two periodic structures is in the infrared region. Moreover, when the hole diameter decreases, the transmission peak shifts slightly, while the transmittance drops rapidly.
Bio-organic-semiconductor-field-effect-transistor based on deoxyribonucleic acid gate dielectric
Authors: Singh Birendra , Sariciftci Niyazi Serdar , Grote James G. , Hopkins Frank K.
Published: August 2006

Organic-based field-effect transistors (OFETs) utilize organic semiconductor materials with low electron mobilities and organic gate oxide materials with low dielectric constants. These have rendered devices with slow operating speeds and high operating voltages, compared with their inorganic silicon-based counter parts. Using a deoxyribonucleic acid (DNA)-based biopolymer, derived from salmon milt and roe sac waste by-products, for the gate dielectric region, we have fabricated an OFET device that exhibits very promising current-voltage characteristics compared with using other organic-based dielectrics. With minimal optimization, using a thin film of DNA-based biopolymer as the gate insulator and pentacene as the semiconductor, we have demonstrated a bio-organic-FET, or BiOFET, in which the current was modulated over three orders of magnitude using gate voltages less than 10V.
Limitations of linear control of thermal convection in a porous medium
Authors: Zhao Hui , Bau Haim H.
Published: August 2006

The ability of linear controllers to stabilize the conduction (no-motion) state of a saturated porous layer heated from below and cooled from above is studied theoretically. Proportional, suboptimal robust (H∞) and linear quadratic Gaussian (H2) controllers are considered. The proportional controller increases the critical Rayleigh number for the onset of convection by as much as a factor of 2. Both the H2 and H∞ controllers stabilize the linearized system at all Rayleigh numbers. Although all these controllers successfully render negative the real part of the linearized system’s eigenvalues, the linear operator of the controlled system is non-normal and disturbances undergo substantial growth prior to their eventual, asymptotic decay. The dynamics of the nonlinear system are examined as a function of the disturbance’s amplitude when the system is subjected to the “most dangerous disturbances.” These computations provide the critical amplitude of the initial conditions above which the system can no longer be stabilized. This critical amplitude decreases as the Rayleigh number increases. To facilitate extensive computations, we examine two-dimensional convection in a box containing a saturated porous medium, heated from below and cooled from above, as a model system. The heating is provided by a large number of individually controlled heaters. The system’s state is estimated by measuring the temperature distribution at the box’s midheight. All the controllers considered here render the linearized, controlled system’s operator non-normal. The transient amplification of disturbances limits the “basin of attraction” of the nonlinear system’s controlled state. By appropriate selection of a controller, one can minimize, but not eliminate, the controlled, linear system’s non-normality.
Magnetic field driving custom assembly in (FeCo) nanocrystals
Authors: Marín P. , López M. , Vlad A. , Hernando A. , Ruiz-González M. L. , González-Calbet J. M.
Published: August 2006

We present the possibility of tuning the nanocrystalline microstructure of Co-rich samples by magnetic field annealing. Custom assembly of nucleated grains, aligned in the field direction, has been observed by means of high resolution transmission microscopy. The organized microstructure was obtained on the basis of the appropriate choice of composition, annealing temperature, related to the initial stages of nanocrystallization process, and magnetic field intensity. The linear pattern of the grains has been explained as a consequence of the counterbalance between magnetic, magnetostatic, and magnetocrystalline couplings, only relevant when the nucleation temperature is well below the Curie temperature of the nucleated phase.
Terahertz detection with tunneling quantum dot intersublevel photodetector
Authors: Su X. H. , Yang J. , Bhattacharya P. , Ariyawansa G. , Perera A. G. U.
Published: August 2006

The characteristics of a tunnel quantum dot intersublevel photodetector, designed for the absorption of terahertz radiation, are described. The absorption region consists of self-organized In0.6Al0.4As∕GaAs quantum dots with tailored electronic properties. Devices exhibit spectral response from 20to75μm (∼4THz) with peak at ∼50μm. The peak responsivity and specific detectivity of the device are 0.45A∕W and 108cmHz1∕2∕W, respectively, at 4.6K for an applied bias of 1V. Response to terahertz radiation is observed up to 150K.
First-principles theory of tunneling currents in metal-oxide-semiconductor structures
Authors: Zhang X.-G. , Lu Zhong-Yi , Pantelides Sokrates T.
Published: August 2006

Ultrathin gate-oxide films and alternate dielectrics call for accurate modeling of tunneling currents. Available models, based on the effective-mass approximation, yield good fits to finite-bias data, but fail for infinitesimal biases. Here we report a first-principles theory of tunneling currents. We show that the conductance at infinitesimal bias is a ground-state property and can be calculated accurately using density-functional theory and the local-density approximation for exchange and correlation. At finite biases, a discontinuity in the exchange-correlation potential must be properly included. Challenges for both theory and experiments are identified.
Angular radiation pattern of electric dipoles embedded in a thin film in the vicinity of a dielectric half space
Authors: Luan L. , Sievert P. R. , Watkins B. , Mu W. , Hong Z. , Ketterson J. B.
Published: August 2006

We report measurements on the angular radiation pattern from an array of dye molecules embedded in a polymethylmethacrylate film deposited on a dielectric hemispherical lens. The radiation pattern is both highly structured and directed, with most of the power being radiated into the media having the higher refractive index. We also present a simulation of the far-field radiation pattern of a dipole embedded in a thin dielectric layer, which apparently has not been investigated before. The simulation matches the experimental results rather well.
The nuclear electric quadrupole moment of antimony from the molecular method
Authors: Haiduke Roberto L. A. , da Silva Albérico B. F. , Visscher Lucas
Published: August 2006

Relativistic Dirac-Coulomb (DC) Hartree-Fock calculations are employed to obtain the analytic electric field gradient (EFG) on the antimony nucleus in the SbN, SbP, SbF, and SbCl molecules. The electronic correlation contribution to the EFGs is included with the DC-CCSD(T) and DC-CCSD-T approaches, also in the four-component framework, using a finite-difference method. The total EFG results, along with the experimental nuclear quadrupole coupling constants from microwave spectroscopy, allow to derive the nuclear quadrupole moments of Sb121 and Sb123, respectively, as −543(11) and −692(14)mb.
Highly stable temperature characteristics of InGaN blue laser diodes
Authors: Ryu H. Y. , Ha K. H. , Lee S. N. , Jang T. , Kim H. K. , Chae J. H. , Kim K. S. , Choi K. K. , Son J. K. , Paek H. S. , Sung Y. J. , Sakong T. , Nam O. H. , Park Y. J.
Published: August 2006

We report stable temperature characteristics of threshold current and output power in InGaN blue laser diodes emitting around 450nm. The threshold current is changed by <3mA in operation temperature range from 20to80°C, and even negative characteristic temperature is observed in a certain temperature range. This peculiar temperature characteristic is attributed to originate from unique carrier transport properties of InGaN quantum wells with high In composition, which is deduced from the simulation of carrier density and optical gain. In addition, slope efficiency is also maintained well and wall plug efficiency is even improved as temperature increases.
Effects of oxide layer thickness on Si-nanocrystal photoluminescence intensity in Si+-implanted SiO2∕Si systems
Authors: Barba D. , Martin F. , Dahmoune C. , Ross G. G.
Published: August 2006

Photoluminescence measurements are used to investigate the light emission of silicon nanocrystals prepared by Si+ implantation into SiO2∕Si layered structures. Strong variations of the luminescence intensity are observed as a function of the SiO2 thickness, for laser excitations at 405 and 488nm. These changes are associated with optical interference which produce spatial modulation of the pump laser intensity and spectral modulation of the PL emission. Model calculations using Fresnel equation solvers where the depth distribution of emitters is adjusted to minimize the difference to the measured PL intensities indicate a wider emitter profile for excitation at 405nm.
Enhanced zero-order transmission of terahertz radiation pulses through very deep metallic gratings with subwavelength slits
Authors: Xing Qirong , Li Shuxin , Tian Zhen , Liang Dong , Zhang Ning , Lang Liying , Chai Lu , Wang Qingyue
Published: August 2006

Very deep metallic grating structures with subwavelength slits are processed to study the transmission properties of terahertz radiation pulses. The experiments have been performed with two samples. The delay of the terahertz pulses and the corresponding enhanced unresonant transmission spectra through the samples are observed. A simple interpretation is presented based on the combination of zero-order diffraction of the gratings with the coupling of the surface plasmon polaritons formed on the top and bottom of the gratings. The experimental results are in good agreement with theoretical calculations.
The origin of molecular distortions: A proposed experimental test
Authors: Englman R. , Vértesi T.
Published: August 2006

Bersuker and co-workers [Vibronic Interactions in Molecules and Crystals (Springer-Verlag, Berlin, 1989); Chem. Rev. 101, 1067 (2001); The Jahn-Teller Effect (Cambridge University Press, Cambridge, England, 2005); J. Chem. Phys. 124, 044321 (2006)] showed that the source of distortions from high symmetry configurations in molecules is vibrational-electronic (vibronic). It is here suggested that if one induces transitions by two consecutive operations (vibrational and electronic) performed in a given and in the reverse order, then the vibronic scenario gives different probabilities for the two orders, while an alternative scenario gives the same probability. The entanglement measure of the vibronic description is noted, and the broader aspect of the suggestion for experimentally testing state entanglements is discussed.
Single-shot dynamic transmission electron microscopy
Authors: LaGrange T. , Armstrong M. R. , Boyden K. , Brown C. G. , Campbell G. H. , Colvin J. D. , DeHope W. J. , Frank A. M. , Gibson D. J. , Hartemann F. V. , Kim J. S. , King W. E. , Pyke B. J. , Reed B. W. , Shirk M. D. , Shuttlesworth R. M. , Stuart B. C. , Torralva B. R. , Browning N. D.
Published: August 2006

A dynamic transmission electron microscope (DTEM) has been designed and implemented to study structural dynamics in condensed matter systems. The DTEM is a conventional in situ transmission electron microscope (TEM) modified to drive material processes with a nanosecond laser, “pump” pulse and measure it shortly afterward with a 30-ns-long probe pulse of ∼107 electrons. An image with a resolution of <20nm may be obtained with a single pulse, largely eliminating the need to average multiple measurements and enabling the study of unique, irreversible events with nanosecond- and nanometer-scale resolution. Space charge effects, while unavoidable at such a high current, may be kept to reasonable levels by appropriate choices of operating parameters. Applications include the study of phase transformations and defect dynamics at length and time scales difficult to access with any other technique. This single-shot approach is complementary to stroboscopic TEM, which is capable of much higher temporal resolution but is restricted to the study of processes with a very high degree of repeatability.
Photoluminescent characteristics of Ni-catalyzed GaN nanowires
Authors: Yoo Jinkyoung , Hong Young-Joon , An Sung Jin , Yi Gyu-Chul , Chon Bonghwan , Joo Taiha , Kim Jong-Wook , Lee Jeong-Soo
Published: August 2006

The authors report on time-integrated and time-resolved photoluminescence (PL) of GaN nanowires grown by the Ni-catalyst-assisted vapor-liquid-solid method. From PL spectra of Ni-catalyzed GaN nanowires at 10K, several PL peaks were observed at 3.472, 3.437, and 3.266eV, respectively. PL peaks at 3.472 and 3.266eV are attributed to neutral-donor-bound excitons and donor-acceptor pair, respectively. Furthermore, according to the results from temperature-dependent and time-resolved PL measurements, the origin of the PL peak at 3.437eV is also discussed.
Phase explosion in atmospheric pressure infrared laser ablation from water-rich targets
Authors: Chen Zhaoyang , Bogaerts Annemie , Vertes Akos
Published: August 2006

A fluid dynamics model was developed for the ablation of water-rich targets by infrared laser pulses at atmospheric pressure. It incorporates the nonlinear absorption of water and the phase explosion due to superheating. The simulation results show that due to two different phase transition mechanisms, the first, slower plume expansion is followed by a vigorous accelerated expansion. The calculated time evolution of the shock front agrees well with the experimental observations. This model sheds new light on the effect of phase explosion on laser ablation dynamics, and it is relevant for the preparative, analytical, and medical applications.
Photocatalytic Ohmic layered nanocomposite for efficient utilization of visible light photons
Authors: Kim Hyun Gyu , Jeong Euh Duck , Borse Pramod H. , Jeon Seongho , Yong Kijung , Lee Jae Sung , Li Wei , Oh Se H.
Published: August 2006

The WO3∕W∕PbBi2Nb1.9Ti0.1O9 photocatalyst was fabricated by depositing the tungsten clusters over the p-type perovskite base material with the chemical vapor deposition method, and later partly oxidizing the surfaces of these clusters to obtain n-type WO3 overlayers and W metal layer as an Ohmic junction. This NCPC showed unprecedented high activity for the photocatalytic oxidation of water, photocurrent generation, and acetaldehyde decomposition under visible light irradiation (λ⩾420nm).
In situ scanning tunneling microscopy during metal-organic vapor phase epitaxy
Authors: Rähmer Bert , Pristovsek Markus , Breusing Markus , Kremzow Raimund , Richter Wolfgang
Published: August 2006

The authors report the first ever in situ scanning tunnelling microscopy measurements in metal-organic vapor phase epitaxy (MOVPE) using an active cooling shield for operation up to 650°C. Apart from fundamental considerations and constraints, some MOVPE specific problems are discussed. The authors present images representing the current status and discuss the effect of tip interaction with the MOVPE process.
Phonon-mediated characterization of microelectromechanical resonators
Authors: Wong Wai-Kin , Palaniapan Moorthi
Published: August 2006

The authors describe an acoustic-phonon technique for dynamic microelectromechanical device characterization. Proof of concept experiments using electrostatic resonators reveal a linear phonon to displacement relationship, with detection gain factors up to 25.2mV∕μm attained for packaged devices. Q values of 21 600 and 465 obtained at operating pressures of 6.0×10−6 and 760Torr, respectively, conform to theoretical estimates. Duffing behavior for nonlinear resonator operation was also characterized as a third order response. As acoustic phonons are well detected on any external location for packaged devices, destructive depackaging for die probing is unnecessary, allowing noninvasive testing and high measurement throughput to be attained.
Degradation mechanism of organic light-emitting device investigated by scanning photoelectron microscopy coupled with peel-off technique
Authors: Shin H. J. , Jung M. C. , Chung J. , Kim K. , Lee J. C. , Lee S. P.
Published: August 2006

The authors present space-resolved spectroscopic data on organic layers of a degraded organic light-emitting device. The data were obtained using a scanning photoelectron microscope (SPEM) coupled with peel-off technique to directly probe the uncontaminated organic layers, which were covered with cathode layer. The SPEM images of the degraded device show different and small size distributions of tris-8-hydroxy quinoline aluminum (Alq3) and hole-transport layers compared to that of as-prepared device. The analysis indicates that bonding strength between Alq3 and cathode layers and between the Alq3 and hole transport layers becomes weak as the device degrades, presumably due to structural deformation of the organic layers.
A Ca
2+
signaling pathway regulates a K
+
channel for low-K response in
Arabidopsis
Authors: Li Legong , Kim Beom-Gi , Cheong Yong Hwa , Pandey Girdhar K. , Luan Sheng
Published: August 2006

Nutrient sensing is critical for plant adaptation to the environment. Because of extensive farming and erosion, low content of mineral nutrients such as potassium (K
+
) in soils becomes a limiting factor for plant growth. In response to low-K conditions, plants enhance their capability of K
+
uptake through an unknown signaling mechanism. Here we report the identification of a Ca
2+
-dependent pathway for low-K response in
Arabidopsis
. We are not aware of any other example of a molecular pathway for a nutrient response in plants. Earlier genetic analyses revealed three genes encoding two Ca
2+
sensors (CBL1 and CBL9) and their target protein kinase (CIPK23) to be critical for plant growth on low-K media and for stomatal regulation, indicating that these calcium signaling components participate in the low-K response and turgor regulation. In this study, we show that the protein kinase CIPK23 interacted with, and phosphorylated, a voltage-gated inward K
+
channel (AKT1) required for K
+
acquisition in
Arabidopsis
. In the
Xenopus
oocyte system, our studies showed that interacting calcium sensors (CBL1 and CBL9) together with target kinase CIPK23, but not either component alone, activated the AKT1 channel in a Ca
2+
-dependent manner, connecting the Ca
2+
signal to enhanced K
+
uptake through activation of a K
+
channel. Disruption of both
CBL1
and
CBL9
or
CIPK23
gene in
Arabidopsis
reduced the AKT1 activity in the mutant roots, confirming that the Ca
2+
-CBL-CIPK pathway functions to orchestrate transporting activities
in planta
according to external K
+
availability.
Dynamics of galaxy cores and supermassive black holes
Authors: Merritt David
Published: August 2006

Recent work on the dynamical evolution of galactic nuclei containing supermassive black holes is reviewed. Topics include galaxy structural properties, collisionless and collisional equilibria, loss-cone dynamics and dynamics of binary and multiple supermassive black holes.
Branch and bound computation of exact p-values
Authors: Bejerano Gill
Published: August 2006

Summary: P-value computation is often used in bioinformatics to quantify the surprise, or significance, associated with a given observation. An implementation is provided that computes the exact p-value associated with any observed sample, against a null multinomial distribution, using the likelihood-ratio statistic. The efficient branch and bound code, far exceeding the full enumeration implemented by commercial packages, is especially useful with small sample, sparse data and rare events, common scenarios in bioinformatics, where approximations are often inaccurate and inappropriate. This code base can also be adapted to compute exact p-values of other statistics in diverse sampling scenarios.

Availability: Freely available at

Contact:  jill@soe.ucsc.edujill
UniGene Tabulator: a full parser for the UniGene format
Authors: Lenzi Luca , Frabetti Flavia , Facchin Federica , Casadei Raffaella , Vitale Lorenza , Canaider Silvia , Carinci Paolo , Zannotti Maria , Strippoli Pierluigi
Published: August 2006

Summary: UniGene Tabulator 1.0 provides a solution for full parsing of UniGene flat file format; it implements a structured graphical representation of each data field present in UniGene following import into a common database managing system usable in a personal computer. This database includes related tables for sequence, protein similarity, sequence-tagged site (STS) and transcript map interval (TXMAP) data, plus a summary table where each record represents a UniGene cluster.

UniGene Tabulator enables full local management of UniGene data, allowing parsing, querying, indexing, retrieving, exporting and analysis of UniGene data in a relational database form, usable on Macintosh (OS X 10.3.9 or later) and Windows (2000, with service pack 4, XP, with service pack 2 or later) operating systems-based computers.

Availability: The current release, including both the FileMaker runtime applications, is freely available at

Contact:  pierluigi.strippoli@unibo.it

Supplementary information: We also distribute a precalculated implementation for current Homo sapiens (build #190, March 2006) and Danio rerio (zebrafish, build #90, March 2006) UniGene data.
Identity Cues: Evidence From and for Intra‐Individual Perspectives on Positive and Negative Stereotyping1
Authors: Pittinsky Todd L. , Shih Margaret J. , Trahan Amy
Published: August 2006

Traditional stereotyping research has adopted an intergroup perspective: Comparisons are made between ways in which targets belonging to different social groups are stereotyped. We adopt an intra‐individual perspective and examine how a single target, belonging to multiple social groups, is stereotyped differently based on identity cues. Participants interacted with a partner (a research confederate) in a series of e‐mail exchanges. The partner used e‐mail addresses that subtly cued either the partner's gender identity, the partner's ethnic identity, or neither identity. This subtle identity cue led participants to stereotype their partners in very different ways, biasing recall in directions consistent with the positive and negative stereotypes associated with the different identities cued. Applications of the findings to the problems that stereotypes create are discussed.
Organizational Citizenship Behaviors as a Function of Empathy, Consideration of Future Consequences, and Employee Time Horizon: An Initial Exploration Using an In‐Basket Simulation of OCBs1
Authors: Joireman Jeff , Daniels Denise , George‐Falvy Jane , Kamdar Dishan
Published: August 2006

We hypothesized that organizational citizenship behaviors (OCBs) represent a social dilemma. Two studies supported this hypothesis. In Study 1, participants rated OCBs as costly to an employee in the short run, and beneficial to an organization in the long run. In Study 2, likelihood of engaging in OCBs was higher among those high in empathy and concern with future consequences; and less likely among those instructed to imagine they would be leaving the company in 3 months for another job. Empathy showed a stronger relationship with OCBs when respondents imagined they would soon leave an organization and that individuals high in concern with future consequences were less likely to engage in OCBs when faced with a short‐term time horizon.
Characterization of a Susceptibility Locus for SLE, SLEB5, on Chromosome 4p14‐13
Authors: Johansson C. M. , Kristjánsdottir H. , Gröndal G. , Steinsson K. , Alarcón‐Riquelme M. E.
Published: August 2006

Systemic lupus erythematosus is a systemic autoimmune disorder of unknown aetiology but is most likely caused by an interaction between several genetic factors and the environment. In a previously published genome scan we presented linkage to a marker on chromosome 4p13 in Icelandic families. Fine mapping of the region has been performed using 10 multicase families from Iceland and the maximum two‐point LOD score was given by marker D4S2974 (Z = 3.57, α = 1). Multipoint analyses of the markers in the region suggest a putative disease gene to be located between markers D4S405 and D4S2381. The maximum multipoint LOD score (Z = 3.76) was given for marker D4S2974 in combination with the novel repeat GT4C2. A family‐specific haplotype was segregating with the disease in each of eight families although a founder haplotype could not be identified. Analysis of recombination events in the patients delimited the susceptibility locus to approximately 3 cM. The susceptibility locus identified probably contains a mutation that has been enriched in the Icelandic population but is less common in other populations. We also show that this region is not identical to a susceptibility locus for SLE located on 4p16 where we detect no linkage.
Th1/Th2 Imbalance, Measured by Circulating and Intracytoplasmic Inflammatory Cytokines – Immunological Alterations in Acute Coronary Syndrome and Stable Coronary Artery Disease
Authors: Szodoray P. , Timar O. , Veres K. , Der H. , Szomjak E. , Lakos G. , Aleksza M. , Nakken B. , Szegedi G. , Soltesz P.
Published: August 2006

To describe how peripheral immune‐parameters reflect the inflammatory alterations of the atherosclerotic plaques in coronary atherosclerosis. We measured general inflammatory markers C‐reactive protein (CRP) and granulocyte activity, lymphocyte subpopulations and their state of activation, evaluated circulating Th1/Th2‐type cytokines, and specific intracytoplasmic cytokines. We investigated the association of immune‐parameters with disease outcome and mortality. Thirty‐three patients with acute coronary syndrome (ACS), 62 with stable coronary artery disease (CAD) and 58 healthy controls were studied. Peripheral blood lymphocyte subgroups were quantified by flow cytometry, soluble cytokines and autoantibodies were assessed using enzyme‐linked immunosorbent assay (ELISA), while intracellular cytokine levels were measured by flow cytometry after intracellular staining. We found elevated levels of CRP and granulocyte activity in ACS versus CAD (P < 0.001, P = 0.017, respectively). Natural killer (NK) cell percentages were elevated, while percentage of T cells to the total lymphocyte count was slightly decreased in ACS compared to controls (P < 0.0001, P = 0.012, respectively). Both forms of coronary atherosclerosis showed significantly higher percentages of activated T cells than controls when stained for the activation markers HLA‐DR3 and CD69+ (ACS: P < 0.0001, P = 0.002, CAD: P < 0.0001, P = 0.018, respectively). IL‐1, IL‐4 and IL‐10 proved significantly higher in ACS versus controls (P = 0.036, P = 0.01, P < 0.0001 respectively). Th1 to Th2 ratio shifted towards a Th1 dominance in both diseases. Both general proinflammatory markers and activated T cells signify CAD. The orchestrated proinflammatory cascade eventually leads to the development of the disease.
The Generation of Extracellular DNA in SLE: the Role of Death and Sex
Authors: Pisetsky D. S. , Jiang N.
Published: August 2006

DNA is a large macromolecule that plays a central role in the pathogenesis of systemic lupus erythematosus (SLE), serving as a target antigen of autoantibodies as well as a major component of immune complexes. These complexes can both promote immune disturbances as well as deposit in the kidney to incite inflammation. While the origin of anti‐DNA autoantibodies in SLE has received intense investigation, the mechanisms by which DNA exits cells to form immune complexes in the circulation is not well understood. To determine the origin of DNA circulating in the blood in SLE, our laboratory has been using a murine model system to track the in vivo fate of DNA from Jurkat T cells that have been made apoptotic or necrotic in vitro and then administered to mice. Results of these studies indicate that DNA from apoptotic and necrotic cells appears in the blood in a time‐ and dose‐dependent manner. Irrespective of origin, this DNA has properties of nucleosomes as shown by its molecular weight. The process of release requires the presence of macrophages and can be modified by glucocorticoids as well as inflammation. In addition, sex may play a role in the generation of extracellular DNA from dead cells as male and female mice differ in their responses in this model. Together, these studies clarify the origin of extracellular DNA circulating in the blood in SLE and suggest steps in this process that can be interdicted by novel therapy.
Cicatricial ectropion: repair with myocutaneous flaps and canthopexy
Authors: Manku Kiran , Leong James K , Ghabrial Raf
Published: August 2006

Abstract

Background:  To evaluate the effectiveness of myocutaneous upper eyelid flaps combined with canthopexy to treat cicatricial lower eyelid ectropion.

Methods:  A prospective non‐comparative case series undertaken in a private practice setting. Consecutive patients with moderate lower eyelid cicatricial ectropion and upper eyelid dermatochalasis underwent transfer of a bipedicle or monopedicle flap from the upper eyelid combined with canthopexy. The main outcome measures included the occurrence of complications, eyelid position and cosmesis.

Results:  Sixty‐two consecutive cases of cicatricial ectropion repair using myocutaneous flaps and canthopexy. After a mean follow up of 20 months, 58 (93.5%) of the cases had the lower lid punctum facing posterosuperior into the tear lake, showed lid globe apposition and satisfactory eyelid position. There was mild recurrence of cicatricial ectropion in four patients (6.5%). There were no cases of graft failure or granuloma formation.

Conclusion:  The use of a myocutaneous flap from the upper eyelid combined with a canthopexy suspension suture for repair of cicatricial ectropion may offer good eyelid position and function. This technique has the advantage of avoiding full thickness blepharotomy and was associated with a low incidence of early recurrence.
Assisted hatching using a 1.48‐µm diode laser: Evaluation of zona opening and zona thinning techniques in human embryos
Authors: YANO KOHJI , KUBO TOSHIKO , ÔHASHI IKUKO , YANO CHIEKO
Published: August 2006

Aim:  We assessed the effectiveness of assisted hatching using a 1.48‐µm diode laser in human embryos, comparing zona opening and zona thinning techniques.

Methods:  A total of 56 day 3 embryos were assigned randomly to a zona opening group, a zona thinning group, or a control group. We then carried out assisted hatching using the OCTAX Laser Shot system (MTG Medical Technology, Altdorf, Germany) in the first two groups. In the zona opening group, the inner membrane of the zona pellucida was broken to create a full‐thickness opening. In the zona thinning group, the inner membrane of the zona pellucida was not breached. After the laser procedure, embryos were cultured to the hatched blastocyst stage.

Results:  Blastocyst development rates did not differ significantly between the three groups. In the zona opening group, blastocysts were significantly more likely to hatch than those in the control group (P ≤ 0.05) and no arrested hatching of blastocysts was observed.

Conclusions:  Assisted hatching using a 1.48‐µm diode laser in the zona opening technique increases the likelihood of blastocyst hatching in human embryos and does not adversely effect subsequent embryo development. (Reprod Med Biol 2006; 5: 221–226)
A meso‐level approach to the 3D numerical analysis of cracking and fracture of concrete materials
Authors: CABALLERO A. , CAROL I. , LÓPEZ C. M.
Published: August 2006

A meso‐mechanical model for the numerical analysis of concrete specimens in 3D has been recently proposed. In this approach, concrete is represented as a composite material with the larger aggregates embedded in a mortar‐plus‐aggregates matrix. Both continuum‐type components are considered linear elastic, while the possibilities of failure are provided with the systematic use of zero‐thickness interface elements equipped with a cohesive fracture constitutive law. These elements are inserted along all potential crack planes in the mesh a priori of the analysis. In this paper, the basic features of the model are summarized, and then results of calculations are presented, which include uniaxial tension and compression loading of 14‐aggregate cubical specimen along X, Y and Z axes. The results confirm the consistency of the approach with physical phenomena and well‐known features of concrete behaviour, and show low scatter when different loading directions are considered. Those cases can also be considered as different specimens subjected to the same type of loading.
MODELING THE ANNUAL PRODUCTION OF INTERTIDAL BENTHIC MICROALGAE IN ESTUARINE ECOSYSTEMS1
Authors: Pinckney James L. , Zingmark Richard G.
Published: August 2006

The purpose of this study was to develop and validate a habitat‐specific production simulation model to quantify annual benthic microalgal production in North Inlet estuary, South Carolina. Using hourly measurements of incident irradiance during 1990–1991 as the forcing function, the simulation model was used to obtain hourly estimates of areal benthic microalgal gross primary production in five habitat types. The model, which was validated using actual measurements of production, showed good (r2= 0.63, P < 0.001) agreement between observed and predicted production in the short Spartina alterniflora Loisel zone habitats showed the highest mean hourly production (61.1 mg C m−2 h−1) while intertidal mudflats had the maximum hourly rate (166.9 mg C m−2 h−1). Daily production was highly variable, primarily due to daily fluctuations in irradiance. Annual estimates of habitat‐specific production were multiplied by the mates of habitat‐specific production were multiplied by the known area of each habitat type to determine total microalgal production for the estuary (3.423 × 109 g C yr−1). Short Spartina zone habitats provided 45% of total microalgal annual production, followed by intertidal mudflats (22%), tall Spartina zones (18%), shallow subtidal (13%) and microalgal production exceeds phytoplankton and microalgal production but is less than Spartina production.
INFECTION, GROWTH, AND COMMUNITY‐LEVEL CONSEQUENCES OF A DIATOM PATHOGEN IN A SONORAN DESERT STREAM1
Authors: Peterson Christopher G. , Dudley Tom L. , Hoagland Kyle D. , Johnson Lisa M.
Published: August 2006

We describe effect of a pathogen that spread through a dense, rapidly growing, benthic diatom community during two infection periods (February and mid‐April 1991) in Sycamore Creek, Arizona. Infected areas appeared as gray rings within a matrix of healthy diatom growth and spread rapidly, eventually covering all benthic substrata and causing algal sloughing (within 2 wk in February and 1 wk in April). Examination of algal material with transmission electron microscopy revealed the presence of invasive bacteria within diatom cells from infected areas, suggesting a pathogenic bacterium as the most probable cause of this phenomenon. Infected area supported lower chlorophyll a concentrations and contained higher percentages of diatom cells with fragmented or reduced chloroplasts than uninfected areas. Spread of the pathogen appeared to be linked most strongly with diatom densities. The infection spread most rapidly in April, when cell densities were highest, and decimated all diatom species populations. The February infection was more species‐specific in its action, affecting large motile and rosetteforming taxa more strongly than small, adnate diatoms. This latter group likely resided at the base of communities and may have been buffered from pathogen transfer by mucilage and/or dentrital particles. Consequently, relative abundance of small, adnate diatom taxa increased in algal communities as a result of the February infection. Pathogen‐induced alteration of diatom species composition and abundance should influence primary production in this ecosystem and affect the dynamics of organisms that exploit algae as a resource.