Vertical electro-absorption modulator design and its integration in a VCSEL

NASA Astrophysics Data System (ADS)

Marigo-Lombart, L.; Calvez, S.; Arnoult, A.; Thienpont, H.; Almuneau, G.; Panajotov, K.

2018-04-01

Electro-absorption modulators, either embedded in CMOS technology or integrated with a semiconductor laser, are of high interest for many applications such as optical communications, signal processing and 3D imaging. Recently, the integration of a surface-normal electro-absorption modulator into a vertical-cavity surface-emitting laser has been considered. In this paper we implement a simple quantum well electro-absorption model and design and optimize an asymmetric Fabry-Pérot semiconductor modulator while considering all physical properties within figures of merit. We also extend this model to account for the impact of temperature on the different parameters involved in the calculation of the absorption, such as refractive indices and exciton transition broadening. Two types of vertical modulator structures have been fabricated and experimentally characterized by reflectivity and photocurrent measurements demonstrating a very good agreement with our model. Finally, preliminary results of an electro-absorption modulator vertically integrated with a vertical-cavity surface-emitting laser device are presented, showing good modulation performances required for high speed communications.

112 Gb/s sub-cycle 16-QAM Nyquist-SCM for intra-datacenter connectivity

NASA Astrophysics Data System (ADS)

Bakopoulos, Paraskevas; Dris, Stefanos; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

2016-03-01

Datacenter traffic is exploding. Ongoing advancements in network infrastructure that ride on Moore's law are unable to keep up, necessitating the introduction of multiplexing and advanced modulation formats for optical interconnects in order to overcome bandwidth limitations, and scale lane speeds with energy- and cost-efficiency to 100 Gb/s and beyond. While the jury is still out as to how this will be achieved, schemes relying on intensity modulation with direct detection (IM/DD) are regarded as particularly attractive, due to their inherent implementation simplicity. Moreover, the scaling-out of datacenters calls for longer transmission reach exceeding 300 m, requiring single-mode solutions. In this work we advocate using 16-QAM sub-cycle Nyquist-SCM as a simpler alternative to discrete multitone (DMT), but which is still more bandwidth-efficient than PAM-4. The proposed optical interconnect is demonstrated at 112 Gb/s, which, to the best of our knowledge, is the highest rate achieved in a single-polarization implementation of SCM. Off-the-shelf components are used: A DFB laser, a 24.3 GHz electro-absorption modulator (EAM) and a limiting photoreceiver, combined with equalization through digital signal processing (DSP) at the receiver. The EAM is driven by a low-swing (<1 V) arbitrary waveform generator (AWG), which produces a 28 Gbaud 16-QAM electrical signal with carrier frequency at ~15 GHz. Tight spectral shaping is leveraged as a means of maintaining signal fidelity when using low-bandwidth electro-optic components; matched root-raised-cosine transmit and receive filters with 0.1 excess bandwidth are thus employed. Performance is assessed through transmission experiments over 1250 m and 2000 m of SMF.

Enhancement of the static extinction ratio by using a dual-section distributed feedback laser integrated with an electro-absorption modulator

NASA Astrophysics Data System (ADS)

Cho, Chun-Hyung; Kim, Jongseong; Sung, Hyuk-Kee

2016-09-01

We report on the enhancement of the static extinction ratio by using a dual-section distributed feedback laser diode integrated with an electro-absorption modulator. A directly- modulated dual-section laser can provide improved modulation performance under a low bias level ( i.e., below the threshold level) compared with a standard directly-modulated laser. By combining the extinction ratio from a dual-section laser with that from an electro-absorption modulator section, a total extinction ratio of 49.6. dB are successfully achieved.

Integration of hybrid silicon lasers and electroabsorption modulators.

PubMed

Sysak, Matthew N; Anthes, Joel O; Bowers, John E; Raday, Omri; Jones, Richard

2008-08-18

We present an integration platform based on quantum well intermixing for multi-section hybrid silicon lasers and electroabsorption modulators. As a demonstration of the technology, we have fabricated discrete sampled grating DBR lasers and sampled grating DBR lasers integrated with InGaAsP/InP electroabsorption modulators. The integrated sampled grating DBR laser-modulators use the as-grown III-V bandgap for optical gain, a 50 nm blue shifted bandgap for the electrabosprtion modulators, and an 80 nm blue shifted bandgap for low loss mirrors. Laser continuous wave operation up to 45 ?C is achieved with output power >1.0 mW and threshold current of <50 mA. The modulator bandwidth is >2GHz with 5 dB DC extinction.

High speed cross-amplitude modulation in concatenated SOA-EAM-SOA.

PubMed

Cleary, Ciaran S; Manning, Robert J

2012-06-18

We observe a near-ideal high speed amplitude impulse response in an SOA-EAM-SOA configuration under optimum conditions. Full amplitude recovery times as low as 10 ps with modulation depths of 70% were observed in pump-probe measurements. System behavior could be controlled by the choice of signal wavelength, SOA current biases and EAM reverse bias voltages. Experimental data and impulse response modelling indicated that the slow tail in the gain response of first SOA was negated by a combination of cross-absorption modulation between pump and modulated CW probe, and self-gain modulation of the modulated CW probe in both the EAM and second SOA.

Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campione, Salvatore; Wood, Michael; Serkland, Darwin K.

Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achievedmore » through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.« less

Sub-micrometer epsilon-near-zero electroabsorption modulators enabled by high-mobility cadmium oxide

DOE PAGES

Campione, Salvatore; Wood, Michael; Serkland, Darwin K.; ...

2017-07-06

Here, epsilon-near-zero materials provide a new path for tailoring light-matter interactions at the nanoscale. In this paper, we analyze a compact electroabsorption modulator based on epsilon-near-zero confinement in transparent conducting oxide films. The non-resonant modulator operates through field-effect carrier density tuning. We compare the performance of modulators composed of two different conducting oxides, namely indium oxide (In2O3) and cadmium oxide (CdO), and show that better modulation performance is achieved when using high-mobility (i.e. low-loss) epsilon-near-zero materials such as CdO. In particular, we show that non-resonant electroabsorption modulators with sub-micron lengths and greater than 5 dB extinction ratios may be achievedmore » through the proper selection of high-mobility transparent conducting oxides, opening a path for device miniaturization and increased modulation depth.« less

Advanced indium phosphide based monolithic integration using quantum well intermixing and MOCVD regrowth

NASA Astrophysics Data System (ADS)

Raring, James W.

The proliferation of the internet has fueled the explosive growth of telecommunications over the past three decades. As a result, the demand for communication systems providing increased bandwidth and flexibility at lower cost continues to rise. Lightwave communication systems meet these demands. The integration of multiple optoelectronic components onto a single chip could revolutionize the photonics industry. Photonic integrated circuits (PIC) provide the potential for cost reduction, decreased loss, decreased power consumption, and drastic space savings over conventional fiber optic communication systems comprised of discrete components. For optimal performance, each component within the PIC may require a unique epitaxial layer structure, band-gap energy, and/or waveguide architecture. Conventional integration methods facilitating such flexibility are increasingly complex and often result in decreased device yield, driving fabrication costs upward. It is this trade-off between performance and device yield that has hindered the scaling of photonic circuits. This dissertation presents high-functionality PICs operating at 10 and 40 Gb/s fabricated using novel integration technologies based on a robust quantum-well-intermixing (QWI) method and metal organic chemical vapor deposition (MOCVD) regrowth. We optimize the QWI process for the integration of high-performance quantum well electroabsorption modulators (QW-EAM) with sampled-grating (SG) DBR lasers to demonstrate the first widely-tunable negative chirp 10 and 40 Gb/s EAM based transmitters. Alone, QWI does not afford the integration of high-performance semiconductor optical amplifiers (SOA) and photodetectors with the transmitters. To overcome this limitation, we have developed a novel high-flexibility integration scheme combining MOCVD regrowth with QWI to merge low optical confinement factor SOAs and 40 Gb/s uni-traveling carrier (UTC) photodiodes on the same chip as the QW-EAM based transmitters. These high-saturation power receiver structures represent the state-of-the-art technologies for even discrete components. Using the novel integration technology, we present the first widely-tunable single-chip device capable of transmit and receive functionality at 40 Gb/s. This device monolithically integrates tunable lasers, EAMs, SOAs, and photodetectors with performance that rivals optimized discrete components. The high-flexibility integration scheme requires only simple blanket regrowth steps and thus breaks the performance versus yield trade-off plaguing conventional fabrication techniques employed for high-functionality PICs.

Fully integrated multi-optoelectronic synthesizer for THz pumping source in wireless communications with rich backup redundancy and wide tuning range.

PubMed

Xu, Junjie; Hou, Lianping; Deng, Qiufang; Han, Liangshun; Liang, Song; Marsh, John H; Zhu, Hongliang

2016-07-06

We report a monolithic photonic integrated circuit (PIC) for THz communication applications. The PIC generates up to 4 optical frequency lines which can be mixed in a separate device to generate THz radiation, and each of the optical lines can be modulated individually to encode data. Physically, the PIC comprises an array of wavelength tunable distributed feedback lasers each with its own electro-absorption modulator. The lasers are designed with a long cavity to operate with a narrow linewidth, typically <4 MHz. The light from the lasers is coupled via an multimode interference (MMI) coupler into a semiconductor optical amplifier (SOA). By appropriate selection and biasing of pairs of lasers, the optical beat signal can be tuned continuously over the range from 0.254 THz to 2.723 THz. The EAM of each channel enables signal leveling balanced between the lasers and realizing data encoding, currently at data rates up to 6.5 Gb/s. The PIC is fabricated using regrowth-free techniques, making it economic for volume applications, such for use in data centers. The PIC also has a degree of redundancy, making it suitable for applications, such as inter-satellite communications, where high reliability is mandatory.

50 Gb/s hybrid silicon traveling-wave electroabsorption modulator.

PubMed

Tang, Yongbo; Chen, Hui-Wen; Jain, Siddharth; Peters, Jonathan D; Westergren, Urban; Bowers, John E

2011-03-28

We have demonstrated a traveling-wave electroabsorption modulator based on the hybrid silicon platform. For a device with a 100 μm active segment, the small-signal electro/optical response renders a 3 dB bandwidth of around 42 GHz and its modulation efficiency reaches 23 GHz/V. A dynamic extinction ratio of 9.8 dB with a driving voltage swing of only 2 V was demonstrated at a transmission rate of 50 Gb/s. This represents a significant improvement for modulators compatible with integration of silicon-based photonic integrated circuits.

Electro-optic Modulation Using a DAST Single-crystal Film in a Fabry-Perot Cavity

NASA Astrophysics Data System (ADS)

Kutty, S. P.

2005-03-01

In this paper, we report a multiple-pass electro-optic modulator using a single- crystal film of 4'-dimethyamino-N-methyl-4-stilbazolium tosylate (DAST) placed inside a Fabry-Perot cavity. The single-crystal film was prepared using the modified shear method. Electro-optic modulation was achieved at 633 nm using field-induced birefringence in the cross polarized geometry including the Fabry-Perot cavity. The modulation due to the electro-optic effect was recorded as a function of phase while the phase was controlled by moving one of the mirrors in the cavity. The observed modulation was high (80 percent) for a low field (0.5V/micron) applied along the charge transfer axis on the film. Similar modulation using the Fabry-Perot cavity with a lower modulation depth was observed involving electroabsorption at 633 nm. Electroabsorption in the DAST film has been recently reported [1]. These are important results considering applications in photonics. [1] ``Electroabsorption in single-crystal film of a second-order optical material,'' R. K. Swamy, S. P. Kutty, J. Titus, S. Khatavkar, and M. Thakur, APL, Vol. 85, 4025, (2004).

Electroabsorption optical modulator

DOEpatents

Skogen, Erik J.

2017-11-21

An electroabsorption modulator incorporates waveguiding regions along the length of the modulator that include quantum wells where at least two of the regions have quantum wells with different bandgaps. In one embodiment of the invention, the regions are arranged such that the quantum wells have bandgaps with decreasing bandgap energy along the length of the modulator from the modulator's input to its output. The bandgap energy of the quantum wells may be decreased in discrete steps or continuously. Advantageously, such an arrangement better distributes the optical absorption as well as the carrier density along the length of the modulator. Further advantageously, the modulator may handle increased optical power as compared with prior art modulators of similar dimensions, which allows for improved link gain when the optical modulator is used in an analog optical communication link.

Improvement of modulation bandwidth in electroabsorption-modulated laser by utilizing the resonance property in bonding wire.

PubMed

Kwon, Oh Kee; Han, Young Tak; Baek, Yong Soon; Chung, Yun C

2012-05-21

We present and demonstrate a simple and cost-effective technique for improving the modulation bandwidth of electroabsorption-modulated laser (EML). This technique utilizes the RF resonance caused by the EML chip (i.e., junction capacitance) and bonding wire (i.e, wire inductance). We analyze the effects of the lengths of the bonding wires on the frequency responses of EML by using an equivalent circuit model. To verify this analysis, we package a lumped EML chip on the sub-mount and measure its frequency responses. The results show that, by using the proposed technique, we can increase the modulation bandwidth of EML from ~16 GHz to ~28 GHz.

Short optical pulse generation at 40 GHz with a bulk electro-absorption modulator packaged device

NASA Astrophysics Data System (ADS)

Langlois, Patrick; Moore, Ronald; Prosyk, Kelvin; O'Keefe, Sean; Oosterom, Jill A.; Betty, Ian; Foster, Robert; Greenspan, Jonathan; Singh, Priti

2003-12-01

Short optical pulse generation at 40GHz and 1540nm wavelength is achieved using fully packaged bulk quaternary electro-absorption modulator modules. Experimental results obtained with broadband and narrowband optimized packaged modules are presented and compared against empirical model predictions. Pulse duty cycle, extinction ratio and chirp are studied as a function of sinusoidal drive voltage and detuning between operating wavelength and modulator absorption band edge. Design rules and performance trade-offs are discussed. Low-chirp pulses with a FWHM of ~12ps and sub-4ps at a rate of 40GHz are demonstrated. Optical time-domain demultiplexing of a 40GHz to a 10GHz pulse train is also demonstrated with better than 20dB extinction ratio.

Reflective electroabsorption modular for compact base station radio-over-fiber systems

NASA Astrophysics Data System (ADS)

Wu, Yang; Chang, Wei-Xi; Yu, Paul K. L.

2003-07-01

A Radio-over-Fiber system with simplified Base Station (BS) is proposed in which a single chip DBR Reflective Electro-absorption Modulator (REAM) serves both as an optical transceiver and as a mixer at the BS. It enables full duplex optical transmission for base band and RF band services simultaneously due to good isolation between uplink and downlink at the same chip. Grating structure is incorporated into the EA modulator for the sake of system design. It also improves yield and efficiency of high-speed devices.

Quadratic Electro-Optic Effect and Electroabsorption in a Novel Nano-Optical Material based on the Nonconjugated Conductive Polymer, Poly(ethylenepyrrolediyl) Derivative

NASA Astrophysics Data System (ADS)

Swamy, R.; Vippa, P.; Rajagopalan, H.; Titus, J.; Thakur, M.; Sen, A.

2005-03-01

We report quadratic electro-optic effect and electroabsorption measurements in a novel nano-optical material based on the nonconjugated conductive polymer, iodine-doped poly(ethylenepyrrolediyl) derivative. Such effect has been recently reported in doped polyisoprene [1]. The measurement was made at 633 nm using field-induced birefringence. A modulation of 0.1% was observed for a field of 0.66 V/micron (film thickness 0.3 micron). The change in refractive index, δn, is 3.35x10-4 and the Kerr constant is 1.2x10-9 m/V^2 which is about 125 times that of nitrobenzene. Modulation due to electroabsorption was 0.05%. The exceptionally large electro-optic effect is most likely due to the specific structure and quantum confinement within a nanometer volume. In contrast, nonlinearity in a conjugated polymer is known to decrease upon iodine doping. [1] Thakur, Swamy and Titus, Macromolecules, Vol.37, 2677, (2004).

Modulation of the relationship between external knee adduction moments and medial joint contact forces across subjects and activities.

PubMed

Trepczynski, Adam; Kutzner, Ines; Bergmann, Georg; Taylor, William R; Heller, Markus O

2014-05-01

The external knee adduction moment (EAM) is often considered a surrogate measure of the distribution of loads across the tibiofemoral joint during walking. This study was undertaken to quantify the relationship between the EAM and directly measured medial tibiofemoral contact forces (Fmed ) in a sample of subjects across a spectrum of activities. The EAM for 9 patients who underwent total knee replacement was calculated using inverse dynamics analysis, while telemetric implants provided Fmed for multiple repetitions of 10 activities, including walking, stair negotiation, sit-to-stand activities, and squatting. The effects of the factors "subject" and "activity" on the relationships between Fmed and EAM were quantified using mixed-effects regression analyses in terms of the root mean square error (RMSE) and the slope of the regression. Across subjects and activities a good correlation between peak EAM and Fmed values was observed, with an overall R(2) value of 0.88. However, the slope of the linear regressions varied between subjects by up to a factor of 2. At peak EAM and Fmed , the RMSE of the regression across all subjects was 35% body weight (%BW), while the maximum error was 127 %BW. The relationship between EAM and Fmed is generally good but varies considerably across subjects and activities. These findings emphasize the limitation of relying solely on the EAM to infer medial joint loading when excessive directed cocontraction of muscles exists and call for further investigations into the soft tissue-related mechanisms that modulate the internal forces at the knee. Copyright © 2014 by the American College of Rheumatology.

30GHz Ge electro-absorption modulator integrated with 3 μm silicon-on-insulator waveguide.

PubMed

Feng, Ning-Ning; Feng, Dazeng; Liao, Shirong; Wang, Xin; Dong, Po; Liang, Hong; Kung, Cheng-Chih; Qian, Wei; Fong, Joan; Shafiiha, Roshanak; Luo, Ying; Cunningham, Jack; Krishnamoorthy, Ashok V; Asghari, Mehdi

2011-04-11

We demonstrate a compact waveguide-based high-speed Ge electro-absorption (EA) modulator integrated with a single mode 3 µm silicon-on-isolator (SOI) waveguide. The Ge EA modulator is based on a horizontally-oriented p-i-n structure butt-coupled with a deep-etched silicon waveguide, which transitions adiabatically to a shallow-etched single mode large core SOI waveguide. The demonstrated device has a compact active region of 1.0 × 45 µm(2), a total insertion loss of 2.5-5 dB and an extinction ratio of 4-7.5 dB over a wavelength range of 1610-1640 nm with -4V(pp) bias. The estimated Δα/α value is in the range of 2-3.3. The 3 dB bandwidth measurements show that the device is capable of operating at more than 30 GHz. Clear eye-diagram openings at 12.5 Gbps demonstrates large signal modulation at high transmission rate. © 2011 Optical Society of America

Polarization-Insensitive Surface Plasmon Polarization Electro-Absorption Modulator Based on Epsilon-Near-Zero Indium Tin Oxide.

PubMed

Jin, Lin; Wen, Long; Liang, Li; Chen, Qin; Sun, Yunfei

2018-02-03

CMOS-compatible plasmonic modulators operating at the telecom wavelength are significant for a variety of on-chip applications. Relying on the manipulation of the transverse magnetic (TM) mode excited on the metal-dielectric interface, most of the previous demonstrations are designed to response only for specific polarization state. In this case, it will lead to a high polarization dependent loss, when the polarization-sensitive modulator integrates to a fiber with random polarization state. Herein, we propose a plasmonic modulator utilizing a metal-oxide indium tin oxide (ITO) wrapped around the silicon waveguide and investigate its optical modulation ability for both the vertical and horizontal polarized guiding light by tuning electro-absorption of ITO with the field-induced carrier injection. The electrically biased modulator with electron accumulated at the ITO/oxide interface allows for epsilon-near-zero (ENZ) mode to be excited at the top or lateral portion of the interface depending on the polarization state of the guiding light. Because of the high localized feature of ENZ mode, efficient electro-absorption can be achieved under the "OFF" state of the device, thus leading to large extinction ratio (ER) for both polarizations in our proposed modulator. Further, the polarization-insensitive modulation is realized by properly tailoring the thickness of oxide in two different stacking directions and therefore matching the ER values for device operating at vertical and horizontal polarized modes. For the optimized geometry configuration, the difference between the ER values of two polarization modes, i.e., the ΔER, as small as 0.01 dB/μm is demonstrated and, simultaneously with coupling efficiency above 74%, is obtained for both polarizations at a wavelength of 1.55 μm. The proposed plasmonic-combined modulator has a potential application in guiding and processing of light from a fiber with a random polarization state.

Polarization-Insensitive Surface Plasmon Polarization Electro-Absorption Modulator Based on Epsilon-Near-Zero Indium Tin Oxide

NASA Astrophysics Data System (ADS)

Jin, Lin; Wen, Long; Liang, Li; Chen, Qin; Sun, Yunfei

2018-02-01

CMOS-compatible plasmonic modulators operating at the telecom wavelength are significant for a variety of on-chip applications. Relying on the manipulation of the transverse magnetic (TM) mode excited on the metal-dielectric interface, most of the previous demonstrations are designed to response only for specific polarization state. In this case, it will lead to a high polarization dependent loss, when the polarization-sensitive modulator integrates to a fiber with random polarization state. Herein, we propose a plasmonic modulator utilizing a metal-oxide indium tin oxide (ITO) wrapped around the silicon waveguide and investigate its optical modulation ability for both the vertical and horizontal polarized guiding light by tuning electro-absorption of ITO with the field-induced carrier injection. The electrically biased modulator with electron accumulated at the ITO/oxide interface allows for epsilon-near-zero (ENZ) mode to be excited at the top or lateral portion of the interface depending on the polarization state of the guiding light. Because of the high localized feature of ENZ mode, efficient electro-absorption can be achieved under the "OFF" state of the device, thus leading to large extinction ratio (ER) for both polarizations in our proposed modulator. Further, the polarization-insensitive modulation is realized by properly tailoring the thickness of oxide in two different stacking directions and therefore matching the ER values for device operating at vertical and horizontal polarized modes. For the optimized geometry configuration, the difference between the ER values of two polarization modes, i.e., the ΔER, as small as 0.01 dB/μm is demonstrated and, simultaneously with coupling efficiency above 74%, is obtained for both polarizations at a wavelength of 1.55 μm. The proposed plasmonic-combined modulator has a potential application in guiding and processing of light from a fiber with a random polarization state.

Generation of ultra-wide and flat optical frequency comb based on electro absorption modulator

NASA Astrophysics Data System (ADS)

Ujjwal; Thangaraj, Jaisingh

2018-05-01

A novel technique is proposed for the generation of ultra-wide and flat optical frequency comb (OFC) based on serially cascading three stages of electro absorption modulators (EAMs) through sinusoidal radio frequency (RF) signals by setting frequencies at f GHz, f/2 GHz and f/4 GHz. Here, the first stage acts as subcarrier generator, the second stage acts as subcarrier doubler, and the third stage acts as subcarrier quadrupler. In addition, a higher number of subcarriers can easily be generated by adjusting the driving sinusoidal RF signal. In this paper, cascading three stages of EAMs driven by 50 GHz, 25 GHz and 12.5 GHz clock sources, we obtain 272 subcarriers with spacing of 2.5 GHz and power deviation within 1 dB. Theoretical analysis of serially cascaded EAMs for subcarrier generation is also investigated. Principal analysis and simulation of this technique are demonstrated.

Novel ultra-wideband (UWB) photonic generation through photodetection and cross-absorption modulation in a single electroabsorption modulator.

PubMed

Wu, Tsu-Hsiu; Wu, Jui-pin; Chiu, Yi-Jen

2010-02-15

We propose and demonstrate, by proof of concept, a novel method of ultra-wide band (UWB) photonic generation using photodetection and cross-absorption modulation (XAM) of multiple quantum wells (MQW) in a single short-terminated electroabsorption modulator (SEAM). As an optical pump pulse excite the MQWs of SEAM waveguide, the probe light pulse with the same polarity can be generated through XAM, simultaneously creating photocurrent pulse propagating along the waveguide. Using the short termination of SEAM accompanied by the delayed microwave line, the photocurrent pulse can be reversed in polarity and re-modulated the waveguide, forming a monocycle UWB optical pulse. An 89 ps cycle of monocycle pulse with 114% fractional bandwidth is obtained, where the electrical power spectrum centered at 4 GHz of frequency ranges from 0.1 GHz to 8 GHz for -10 dB drops. Meanwhile, the generation processing is also confirmed by observing the same cycle of monocycle electrical pulse from the photodetection of SEAM. The whole optical processing is performed inside a compact semiconductor device, suggesting the optoelectronic integration template has a potential for the application of UWB photonic generation.

1.55 µm high speed low chirp electroabsorption modulated laser arrays based on SAG scheme.

PubMed

Cheng, Yuanbing; Wang, Qi Jie; Pan, Jiaoqing

2014-12-15

We demonstrate a cost-effective 1.55 µm low chirp 4 × 25 Gbit/s electroabsorption modulated laser (EML) array with 0.8 nm channel spacing by varying ridge width of the lasers and using selective area growth (SAG) integration scheme. The devices for all the 4 channels within the EML array show uniform threshold currents around 18 mA and high SMSRs over 45 dB. The output optical power of each channel is about 9 mW at an injection current of 100 mA. The typical chirp value of single EML measured by a fiber resonance method varied from 2.2 to -4 as the bias voltage was increased from 0 V to 2.5 V. These results show that the EML array is a suitable light source for 100 Gbit/s optical transmissions.

High-Q microwave photonic filter with a tuned modulator.

PubMed

Capmany, J; Mora, J; Ortega, B; Pastor, D

2005-09-01

We propose the use of tuned electro-optic or electroabsorption external modulators to implement high-quality (high-Q) factor, single-bandpass photonic filters for microwave signals. Using this approach, we experimentally demonstrate a transversal finite impulse response with a Q factor of 237. This is to our knowledge the highest value ever reported for a passive finite impulse-response microwave photonic filter.

Waveguide-based electro-absorption modulator performance: comparative analysis

NASA Astrophysics Data System (ADS)

Amin, Rubab; Khurgin, Jacob B.; Sorger, Volker J.

2018-06-01

Electro-optic modulation is a key function for data communication. Given the vast amount of data handled, understanding the intricate physics and trade-offs of modulators on-chip allows revealing performance regimes not explored yet. Here we show a holistic performance analysis for waveguide-based electro-absorption modulators. Our approach centers around material properties revealing obtainable optical absorption leading to effective modal cross-section, and material broadening effects. Taken together both describe the modulator physical behavior entirely. We consider a plurality of material modulation classes to include two-level absorbers such as quantum dots, free carrier accumulation or depletion such as ITO or Silicon, two-dimensional electron gas in semiconductors such as quantum wells, Pauli blocking in Graphene, and excitons in two-dimensional atomic layered materials such as found in transition metal dichalcogendies. Our results show that reducing the modal area generally improves modulator performance defined by the amount of induced electrical charge, and hence the energy-per-bit function, required switching the signal. We find that broadening increases the amount of switching charge needed. While some material classes allow for reduced broadening such as quantum dots and 2-dimensional materials due to their reduced Coulomb screening leading to increased oscillator strengths, the sharpness of broadening is overshadowed by thermal effects independent of the material class. Further we find that plasmonics allows the switching charge and energy-per-bit function to be reduced by about one order of magnitude compared to bulk photonics. This analysis is aimed as a guide for the community to predict anticipated modulator performance based on both existing and emerging materials.

Many-body design of highly strained GaInNAs electroabsorption modulators on GaInAs ternary substrates

NASA Astrophysics Data System (ADS)

Fujisawa, Takeshi; Arai, Masakazu; Kano, Fumiyoshi

2010-05-01

Electroabsorption in highly strained GaInAs and GaInNAs quantum wells (QWs) grown on GaInAs or quasi-GaInAs substrates is investigated by using microscopic many-body theory. The effects of various parameters, such as strain, barrier height, substrate composition, and temperature are thoroughly examined. It is shown that the value of the absorption coefficient strongly depends on the depth of the QWs under large bias electric field due to the small overlap integral of wave functions between the conduction and valence bands. The use of GaInNAs QWs makes the strain in the well layer very small. Further, the effective quantum-well depth is increased in GaInNAs QWs due to the anticrossing interaction between the conduction and N-resonant bands, making it possible to obtain larger absorption coefficient under large bias electric fields without using wide-band gap materials for barriers.

Strongly-guided indium phosphide/indium gallium arsenic phosphide Mach-Zehnder modulator for optical communications

NASA Astrophysics Data System (ADS)

Betty, Ian Brian

2006-12-01

The development of strongly-guided InP/In1-x GaxAsyP 1-y based Mach-Zehnder optical modulators for 10Gb/s telecommunications is detailed. The modulators have insertion losses including coupling as low as 4.5dB, due to the incorporation of monolithically integrated optical mode spot-size converters (SSC's). The modulators are optimized to produce system performance that is independent of optical coupling alignment and for wavelength operation between 1525nm and 1565nm. A negatively chirped Mach-Zehnder modulator design is demonstrated, giving optimal dispersion-limited reach for 10Gb/s ON/OFF-keying modulation. It is shown that the optical system performance for this design can be determined from purely DC based optical measurements. A Mach-Zehnder modulator design invoking nearly no transient frequency shifts under intensity modulation is also presented, for the first time, using phase-shifter implementations based on the Quantum-Confined-Stark-Effect (QCSE). The performance impact on the modulator from the higher-order vertical and lateral waveguide modes found in strongly-guided waveguides has been determined. The impact of these higher-order modes has been minimized using the design of the waveguide bends, MMI structures, and doping profiles. The fabrication process and optical design for the spot-size mode converters are also thoroughly explored. The SSC structures are based on butt-joined vertically tapered passive waveguide cores within laterally flared strongly-guided ridges, making them compatible with any strong-guiding waveguide structure. The flexibility of the SSC process is demonstrated by the superior performance it has also enabled in a 40Gb/s electro-absorption modulator. The presented electro-absorption modulator has 3.6dB fiber-to-fiber insertion loss, polarization dependent loss (PDL) of only 0.3dB over 15dB extinction, and low absolute chirp (|alpha H| < 0.6) over the full dynamic range.

Nitric oxide synthase 2 is required for conversion of pro-fibrogenic inflammatory CD133(+) progenitors into F4/80(+) macrophages in experimental autoimmune myocarditis.

PubMed

Blyszczuk, Przemyslaw; Berthonneche, Corrine; Behnke, Silvia; Glönkler, Marcel; Moch, Holger; Pedrazzini, Thierry; Lüscher, Thomas F; Eriksson, Urs; Kania, Gabriela

2013-02-01

Experimental autoimmune myocarditis (EAM) model mirrors important mechanisms of inflammatory dilated cardiomyopathy (iDCM). In EAM, inflammatory CD133(+) progenitors are a major cellular source of cardiac myofibroblasts in the post-inflammatory myocardium. We hypothesized that exogenous delivery of macrophage-colony-stimulating factor (M-CSF) can stimulate macrophage lineage differentiation of inflammatory progenitors and, therefore, prevent their naturally occurring myofibroblast fate in EAM. EAM was induced in wild-type (BALB/c) and nitric oxide synthase 2-deficient (Nos2(-/-)) mice and CD133(+) progenitors were isolated from inflamed hearts. In vitro, M-CSF converted inflammatory CD133(+) progenitors into nitric oxide-producing F4/80(+) macrophages and prevented transforming growth factor-β-mediated myofibroblast differentiation. Importantly, only a subset of heart-infiltrating CD133(+) progenitors expresses macrophage-specific antigen F4/80 in EAM. These CD133(+)/F4/80(hi) cells show impaired myofibrogenic potential compared with CD133(+)/F4/80(-) cells. M-CSF treatment of wild-type mice with EAM at the peak of disease markedly increased CD133(+)/F4/80(hi) cells in the myocardium, and CD133(+) progenitors isolated from M-CSF-treated mice failed to differentiate into myofibroblasts. In contrast, M-CSF was not effective in converting CD133(+) progenitors from inflamed hearts of Nos2(-/-) mice into macrophages, and M-CSF treatment did not result in increased CD133(+)/F4/80(hi) cell population in hearts of Nos2(-/-) mice. Accordingly, M-CSF prevented post-inflammatory fibrosis and left ventricular dysfunction in wild-type but not in Nos2(-/-) mice. Active and NOS2-dependent induction of macrophage lineage differentiation abrogates the myofibrogenic potential of heart-infiltrating CD133(+) progenitors. Modulating the in vivo differentiation fate of specific progenitors might become a novel approach for the treatment of inflammatory heart diseases.

Energy level alignment and sub-bandgap charge generation in polymer:fullerene bulk heterojunction solar cells.

PubMed

Tsang, Sai-Wing; Chen, Song; So, Franky

2013-05-07

Using charge modulated electroabsorption spectroscopy (CMEAS), for the first time, the energy level alignment of a polymer:fullerene bulk heterojunction photovoltaic cell is directly measured. The charge-transfer excitons generated by the sub-bandgap optical pumping are coupled with the modulating electric field and introduce subtle changes in optical absorption in the sub-bandgap region. This minimum required energy for sub-bandgap charge genreation is defined as the effective bandgap. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

AlGaInAs EML having high extinction ratios fabricated by identical epitaxial layer technique

NASA Astrophysics Data System (ADS)

Deng, Qiufang; Guo, Lu; Liang, Song; Sun, Siwei; Xie, Xiao; Zhu, Hongliang; Wang, Wei

2018-04-01

AlGaInAs electroabsorption-modulated lasers (EMLs) fabricated by identical epitaxial layer technique are demonstrated. The EML device shows an infinite characteristic temperature when the temperature ranges from 20 oC to 30 oC. The integrated modulator has static extinction ratios of larger than 20 dB at a reverse bias voltage of - 2 V. The small signal modulation bandwidth of the modulator is larger than 11 GHz. At 10 Gb/s data modulation, the dynamic extinction ratio is about 9.5 dB in a back to back test configuration. Because only a simple fabrication procedure is needed, our EMLs are promising low cost light sources for optical fiber transmission applications.

In vitro metabolism of a novel synthetic cannabinoid, EAM-2201, in human liver microsomes and human recombinant cytochrome P450s.

PubMed

Kim, Ju Hyun; Kim, Hee Seung; Kong, Tae Yeon; Lee, Joo Young; Kim, Jin Young; In, Moon Kyo; Lee, Hye Suk

2016-02-05

In vitro metabolism of a new synthetic cannabinoid, EAM-2201, has been investigated with human liver microsomes and major cDNA-expressed cytochrome P450 (CYP) isozymes using liquid chromatography-high resolution mass spectrometry (LC-HRMS). Incubation of EAM-2201 with human liver microsomes in the presence of NADPH resulted in the formation of 37 metabolites, including nine hydroxy-EAM-2201 (M1-M9), five dihydroxy-EAM-2201 (M10-M14), dihydrodiol-EAM-2201 (M15), oxidative defluorinated EAM-2201 (M16), two hydroxy-M16 (M17 and M18), three dihydroxy-M16 (M19-M21), N-dealkyl-EAM-2201 (M22), two hydroxy-M22 (M23 and M24), dihydroxy-M22 (M25), EAM-2201 N-pentanoic acid (M26), hydroxy-M26 (M27), dehydro-EAM-2201 (M28), hydroxy-M28 (M29), seven dihydroxy-M28 (M30-M36), and oxidative defluorinated hydroxy-M28 (M37). Multiple CYPs, including CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6, 2J2, 3A4, and 3A5, were involved in the metabolism of EAM-2201. In conclusion, EAM-2201 is extensively metabolized by CYPs and its metabolites can be used as an indicator of EAM-2201 abuse. Copyright © 2015 Elsevier B.V. All rights reserved.

Particle-in-a-box model of exciton absorption and electroabsorption in conjugated polymers

NASA Astrophysics Data System (ADS)

Pedersen, Thomas G.

2000-12-01

The recently proposed particle-in-a-box model of one-dimensional excitons in conjugated polymers is applied in calculations of optical absorption and electroabsorption spectra. It is demonstrated that for polymers of long conjugation length a superposition of single exciton resonances produces a line shape characterized by a square-root singularity in agreement with experimental spectra near the absorption edge. The effects of finite conjugation length on both absorption and electroabsorption spectra are analyzed.

Solid State Research, 1975:4

DTIC Science & Technology

1975-11-15

2.8kA/cm for broad- area devices, has been achieved for Ga. In As, _ P /inP double-heterostructure 1 -x x 1 -y y diode lasers emitting ... LIGHT (b) reverse-biasing the p -n~ junction). This should facilitate the fabrication of modulators and switches using electroabsorption and...temperature operation of Ga In As, P /inP double-heterostructure (DH) diode lasers has been achieved. Broad-area devices emitting at 1.1

Mapping-by-Sequencing Identifies HvPHYTOCHROME C as a Candidate Gene for the early maturity 5 Locus Modulating the Circadian Clock and Photoperiodic Flowering in Barley

PubMed Central

Pankin, Artem; Campoli, Chiara; Dong, Xue; Kilian, Benjamin; Sharma, Rajiv; Himmelbach, Axel; Saini, Reena; Davis, Seth J; Stein, Nils; Schneeberger, Korbinian; von Korff, Maria

2014-01-01

Phytochromes play an important role in light signaling and photoperiodic control of flowering time in plants. Here we propose that the red/far-red light photoreceptor HvPHYTOCHROME C (HvPHYC), carrying a mutation in a conserved region of the GAF domain, is a candidate underlying the early maturity 5 locus in barley (Hordeum vulgare L.). We fine mapped the gene using a mapping-by-sequencing approach applied on the whole-exome capture data from bulked early flowering segregants derived from a backcross of the Bowman(eam5) introgression line. We demonstrate that eam5 disrupts circadian expression of clock genes. Moreover, it interacts with the major photoperiod response gene Ppd-H1 to accelerate flowering under noninductive short days. Our results suggest that HvPHYC participates in transmission of light signals to the circadian clock and thus modulates light-dependent processes such as photoperiodic regulation of flowering. PMID:24996910

Communication using VCSEL laser array

NASA Technical Reports Server (NTRS)

Goorjian, Peter M. (Inventor)

2008-01-01

Ultrafast directional beam switching, using coupled vertical cavity surface emitting lasers (VCSELs) is combined with a light modulator to provide information transfer at bit rates of tens of GHz. This approach is demonstrated to achieve beam switching frequencies of 32-50 GHz in some embodiments and directional beam switching with angular differences of about eight degrees. This switching scheme is likely to be useful for ultrafast optical networks at frequencies much higher than achievable with other approaches. A Mach-Zehnder interferometer, a Fabry-Perot etalon, or a semiconductor-based electro-absorption transmission channel, among others, can be used as a light modulator.

Vocational Training and the Environment: Sustainability and Employment

ERIC Educational Resources Information Center

Villar, Alberto Martinez

2008-01-01

The inclusion of an Environmental Awareness Module (EAM) within Vocational Education and Training (VET) in Spain is considered a factor of overriding importance due to the current need to incorporate environmental awareness within society as a whole but also within particular occupations and professional practices involved both in jobs relating to…

Composition and temporal stability of turf sediments on inner-shelf coral reefs.

PubMed

Gordon, Sophie E; Goatley, Christopher H R; Bellwood, David R

2016-10-15

Elevated sediment loads within the epilithic algal matrix (EAM) of coral reefs can increase coral mortality and inhibit herbivory. Yet the composition, distribution and temporal variability of EAM sediment loads are poorly known, especially on inshore reefs. This study quantified EAM sediment loads (including organic particulates) and algal length across the reef profile of two bays at Orpheus Island (inner-shelf Great Barrier Reef) over a six month period. We examined the total sediment mass, organic load, carbonate and silicate content, and the particle sizes of EAM sediments. Throughout the study period, all EAM sediment variables exhibited marked variation among reef zones. However, EAM sediment loads and algal length were consistent between bays and over time, despite major seasonal variation in climate including a severe tropical cyclone. This study provides a comprehensive description of EAM sediments on inshore reefs and highlights the exceptional temporal stability of EAM sediments on coral reefs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Process-Based Cost Modeling of Photonics Manufacture: The Cost Competitiveness of Monolithic Integration of a 1550-nm DFB Laser and an Electroabsorptive Modulator on an InP Platform

NASA Astrophysics Data System (ADS)

Fuchs, Erica R. H.; Bruce, E. J.; Ram, R. J.; Kirchain, Randolph E.

2006-08-01

The monolithic integration of components holds promise to increase network functionality and reduce packaging expense. Integration also drives down yield due to manufacturing complexity and the compounding of failures across devices. Consensus is lacking on the economically preferred extent of integration. Previous studies on the cost feasibility of integration have used high-level estimation methods. This study instead focuses on accurate-to-industry detail, basing a process-based cost model of device manufacture on data collected from 20 firms across the optoelectronics supply chain. The model presented allows for the definition of process organization, including testing, as well as processing conditions, operational characteristics, and level of automation at each step. This study focuses on the cost implications of integration of a 1550-nm DFB laser with an electroabsorptive modulator on an InP platform. Results show the monolithically integrated design to be more cost competitive over discrete component options regardless of production scale. Dominant cost drivers are packaging, testing, and assembly. Leveraging the technical detail underlying model projections, component alignment, bonding, and metal-organic chemical vapor deposition (MOCVD) are identified as processes where technical improvements are most critical to lowering costs. Such results should encourage exploration of the cost advantages of further integration and focus cost-driven technology development.

Electroabsorption in triphenylamine-based hole-transporting materials for organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Stampor, Waldemar; Mróz, Wojciech

2007-01-01

Electric-field modulated absorption (EA) spectra have been studied in solid films of triphenylamine (TPA)-based compounds, commonly used as hole-transporting materials in organic light-emitting diodes. The electroabsorption spectra of triphenyldiamine derivatives (TPD and TAPC) and a starburst amine dendrimer m-MTDATA are compared with those of TPA which is the building block of the molecules. The EA results indicate that properties of excited states of m-MTDATA and TAPC can be qualitatively rationalized in the terms of exciton interaction between TPA constituents. The lowest energy electronic excitations of m-MTDATA dendrimer are strongly delocalized within the area of the whole molecule. In contrast to m-MTDATA and TAPC, the TPD behavior in the electric field shows individual features that can not be derived from the optical properties of TPA monomers alone. The influence of excited state degeneracy on EA spectra is discussed. The consistent qualitative interpretation of EA spectra for compounds under investigation has been reached assuming that the second derivative lineshapes of EA signal originate from degenerate (in TPA and m-MTDATA) and possible quasi-degenerate states (in TAPC and TPD).

Sympathetic nerve blocks promote anti-inflammatory response by activating the JAK2-STAT3-mediated signaling cascade in rat myocarditis models: A novel mechanism with clinical implications.

PubMed

Park, Hyelim; Park, Hyewon; Mun, Dasom; Kim, Michael; Pak, Hui-Nam; Lee, Moon-Hyoung; Joung, Boyoung

2018-05-01

Left stellectomy has become an important therapeutic option for patients with potentially fatal arrhythmias. However, the antiarrhythmic mechanism of left stellectomy is not well known. The cholinergic anti-inflammatory pathway (CAIP) is a complex immune mechanism that regulates peripheral inflammatory responses. The purpose of this study was to evaluate the effect of left stellectomy on CAIP using rat experimental autoimmune myocarditis (EAM) models. EAM was produced by injecting 2 mg of porcine cardiac myosin into the footpads of rats. Left stellectomy was performed before EAM induction. We evaluated the effect of left stellectomy on arrhythmic events, survival, inflammation, and CAIP in rats without and with EAM. Left stellectomy prevented arrhythmia and improved survival in EAM rats. Left stellectomy decreased the levels of tumor necrosis factor α, interleukin 6, and high mobility group box 1 (P < .05 vs EAM) in serum and heart tissues from EAM rats. In heart rate variability analysis, high-frequency peaks of the power spectrum densities, reflecting parasympathetic cardiovagal tone, were significantly decreased in EAM rats, but increased after left stellectomy. The ratios of phosphorylated STAT3/STAT3 (signal transducer and activator of transcription 3) and phosphorylated JAK2/JAK2 (Janus kinase 2) decreased in cell lysates of the spleen, liver, and heart in EAM rats. However, the same ratios significantly increased after left stellectomy. Nuclear factor κB in cell lysates of the spleen, liver, and heart increased in EAM rats, but decreased after left stellectomy. In EAM models, left stellectomy increased survival of the rats while showing antiarrhythmic effects with reduced inflammation via activation of the JAK2-STAT3-mediated signaling cascade. Our findings suggest an exciting opportunity to develop new and novel therapeutics to attenuate cardiac inflammation. Copyright © 2017 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Characteristics, processes, and causes of the spatio-temporal variabilities of the East Asian monsoon system

NASA Astrophysics Data System (ADS)

Huang, Ronghui; Chen, Jilong; Wang, Lin; Lin, Zhongda

2012-09-01

Recent advances in the study of the characteristics, processes, and causes of spatio-temporal variabilities of the East Asian monsoon (EAM) system are reviewed in this paper. The understanding of the EAM system has improved in many aspects: the basic characteristics of horizontal and vertical structures, the annual cycle of the East Asian summer monsoon (EASM) system and the East Asian winter monsoon (EAWM) system, the characteristics of the spatio-temporal variabilities of the EASM system and the EAWM system, and especially the multiple modes of the EAM system and their spatio-temporal variabilities. Some new results have also been achieved in understanding the atmosphere-ocean interaction and atmosphere-land interaction processes that affect the variability of the EAM system. Based on recent studies, the EAM system can be seen as more than a circulation system, it can be viewed as an atmosphere-ocean-land coupled system, namely, the EAM climate system. In addition, further progress has been made in diagnosing the internal physical mechanisms of EAM climate system variability, especially regarding the characteristics and properties of the East Asia-Pacific (EAP) teleconnection over East Asia and the North Pacific, the "Silk Road" teleconnection along the westerly jet stream in the upper troposphere over the Asian continent, and the dynamical effects of quasi-stationary planetary wave activity on EAM system variability. At the end of the paper, some scientific problems regarding understanding the EAM system variability are proposed for further study.

Apigenin Attenuates Experimental Autoimmune Myocarditis by Modulating Th1/Th2 Cytokine Balance in Mice.

PubMed

Zhang, Shouxin; Liu, Xiaoyan; Sun, Chengming; Yang, Jun; Wang, Lihong; Liu, Jie; Gong, Lei; Jing, Yanyan

2016-04-01

This study aims to investigate the protective effect of apigenin on the development of experimental autoimmune myocarditis (EAM) and the underlying mechanisms. An EAM model was induced in BALB/c mice by the injection of porcine cardiac myosin. Apigenin was orally administered from day 1 to 21. The severity of myocarditis was assessed by determination of heart weight/body weight ratio (HW/BW) and histopathological evaluation. Echocardiography was conducted to evaluate the cardiac function and heart structure. Antigen-specific T cell proliferation responses to cardiac myosin were evaluated by the lymphocyte proliferation assay. ELISA was used to determine serum levels of type 1 helper (Th1) and Th2 cytokines. Apigenin treatment significantly decreased HW/BW. Histopathologic analysis showed that the infiltration of inflammatory cells was reduced significantly by apigenin treatment. Meanwhile, apigenin administration effectively ameliorated autoimmune myocarditis-induced cardiac hypertrophy and cardiac dysfunction as well as inhibited lymphocyte proliferation in mice immunized with myosin. Furthermore, Th1 cytokines tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), and interleukin-2 (IL-2) were significantly downregulated, while Th2 cytokines IL-4 and IL-10 were markedly upregulated. The results indicated that apigenin can alleviate EAM due to its immunomodulatory reactions in modification of helper T cell balance.

Self-starting picosecond optical pulse source using stimulated Brillouin scattering in an optical fiber.

PubMed

Tang, W W; Shu, C

2005-02-21

We demonstrate a regeneratively mode-locked optical pulse source at about 10 GHz using an optoelectronic oscillator constructed with an electro-absorption modulator integrated distributed feedback laser diode. The 10 GHz RF component is derived from the interaction between the pump wave and the backscattered, frequency-downshifted Stokes wave resulted from stimulated Brillouin scattering in an optical fiber. The component serves as a modulation source for the 1556 nm laser diode without the need for any electrical or optical RF filter to perform the frequency extraction. Dispersion-compensated fiber, dispersion-shifted fiber, and standard single-mode fiber have been used respectively to generate optical pulses at variable repetition rates.

Graphene-silicon phase modulators with gigahertz bandwidth

NASA Astrophysics Data System (ADS)

Sorianello, V.; Midrio, M.; Contestabile, G.; Asselberghs, I.; Van Campenhout, J.; Huyghebaert, C.; Goykhman, I.; Ott, A. K.; Ferrari, A. C.; Romagnoli, M.

2018-01-01

The modulator is a key component in optical communications. Several graphene-based amplitude modulators have been reported based on electro-absorption. However, graphene phase modulators (GPMs) are necessary for functions such as applying complex modulation formats or making switches or phased arrays. Here, we present a 10 Gb s-1 GPM integrated in a Mach-Zehnder interferometer configuration. This is a compact device based on a graphene-insulator-silicon capacitor, with a phase-shifter length of 300 μm and extinction ratio of 35 dB. The GPM has a modulation efficiency of 0.28 V cm at 1,550 nm. It has 5 GHz electro-optical bandwidth and operates at 10 Gb s-1 with 2 V peak-to-peak driving voltage in a push-pull configuration for binary transmission of a non-return-to-zero data stream over 50 km of single-mode fibre. This device is the key building block for graphene-based integrated photonics, enabling compact and energy-efficient hybrid graphene-silicon modulators for telecom, datacom and other applications.

Algal Turf Sediments and Sediment Production by Parrotfishes across the Continental Shelf of the Northern Great Barrier Reef

PubMed Central

Goatley, Christopher H. R.; Bellwood, David R.

2017-01-01

Sediments are found in the epilithic algal matrix (EAM) of all coral reefs and play important roles in ecological processes. Although we have some understanding of patterns of EAM sediments across individual reefs, our knowledge of patterns across broader spatial scales is limited. We used an underwater vacuum sampler to quantify patterns in two of the most ecologically relevant factors of EAM sediments across the Great Barrier Reef: total load and grain size distribution. We compare these patterns with rates of sediment production and reworking by parrotfishes to gain insights into the potential contribution of parrotfishes to EAM sediments. Inner-shelf reef EAMs had the highest sediment loads with a mean of 864.1 g m-2, compared to 126.8 g m-2 and 287.4 g m-2 on mid- and outer-shelf reefs, respectively. High sediment loads were expected on inner-shelf reefs due to their proximity to the mainland, however, terrigenous siliceous sediments only accounted for 13–24% of total mass. On inner-shelf reef crests parrotfishes would take three months to produce the equivalent mass of sediment found in the EAM. On the outer-shelf it would take just three days, suggesting that inner-shelf EAMs are characterised by low rates of sediment turnover. By contrast, on-reef sediment production by parrotfishes is high on outer-shelf crests. However, exposure to oceanic swells means that much of this production is likely to be lost. Hydrodynamic activity also appears to structure sediment patterns at within-reef scales, with coarser sediments (> 250 μm) typifying exposed reef crest EAMs, and finer sediments (< 250 μm) typifying sheltered back-reef EAMs. As both the load and grain size of EAM sediments mediate a number of important ecological processes on coral reefs, the observed sediment gradients are likely to play a key role in the structure and function of the associated coral reef communities. PMID:28122042

Investigation of quadratic electro-optic effects and electro-absorption process in GaN/AlGaN spherical quantum dot

PubMed Central

2014-01-01

Quadratic electro-optic effects (QEOEs) and electro-absorption (EA) process in a GaN/AlGaN spherical quantum dot are theoretically investigated. It is found that the magnitude and resonant position of third-order nonlinear optical susceptibility depend on the nanostructure size and aluminum mole fraction. With increase of the well width and barrier potential, quadratic electro-optic effect and electro-absorption process nonlinear susceptibilities are decreased and blueshifted. The results show that the DC Kerr effect in this case is much larger than that in the bulk case. Finally, it is observed that QEOEs and EA susceptibilities decrease and broaden with the decrease of relaxation time. PMID:24646318

Mitigation of Rayleigh crosstalk using noise suppression technique in 10-Gb/s REAM-SOA.

PubMed

Jeong, Jong Sool; Kim, Hyun-Soo; Choi, Byung-Seok; Kim, Dong Churl; Kim, Ki-Soo; Park, Mi-Ran; Kwon, O-Kyun

2012-11-19

We demonstrate a mitigation of Rayleigh back-scattering (RBS) impact in 10-Gb/s reflective electroabsorption modulator monolithically integrated with semiconductor optical amplifier (REAM-SOA). The technique is based on the intensity-noise suppression of the centralized incoherent seed-light, which enables smooth evolution of deployed DWDM applications. We exhibit the power penalty of less than 1 dB at the large RBS crosstalk value of about 8 dB when the optical power of seed-light is lowered about -10 dBm.

Optical XOR gate

DOEpatents

Vawter, G. Allen

2013-11-12

An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Optical NOR gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Tauke-Pedretti, Anna [Albuquerque, NM

2011-09-06

An optical NOR gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical NOR gate utilizes two digital optical inputs and a continuous light input to provide a NOR function digital optical output. The optical NOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Validation of a novel CARTOSEG™ segmentation module software for contrast-enhanced computed tomography-guided radiofrequency ablation in patients with atrial fibrillation.

PubMed

Imanli, Hasan; Bhatty, Shaun; Jeudy, Jean; Ghzally, Yousra; Ume, Kiddy; Vunnam, Rama; Itah, Refael; Amit, Mati; Duell, John; See, Vincent; Shorofsky, Stephen; Dickfeld, Timm M

2017-11-01

Visualization of left atrial (LA) anatomy using image integration modules has been associated with decreased radiation exposure and improved procedural outcome when used for guidance of pulmonary vein isolation (PVI) in atrial fibrillation (AF) ablation. We evaluated the CARTOSEG™ CT Segmentation Module (Biosense Webster, Inc.) that offers a new CT-specific semiautomatic reconstruction of the atrial endocardium. The CARTOSEG™ CT Segmentation Module software was assessed prospectively in 80 patients undergoing AF ablation. Using preprocedural contrast-enhanced computed tomography (CE-CT), cardiac chambers, coronary sinus (CS), and esophagus were semiautomatically segmented. Segmentation quality was assessed from 1 (poor) to 4 (excellent). The reconstructed structures were registered with the electroanatomic map (EAM). PVI was performed using the registered 3D images. Semiautomatic reconstruction of the heart chambers was successfully performed in all 80 patients with AF. CE-CT DICOM file import, semiautomatic segmentation of cardiac chambers, esophagus, and CS was performed in 185 ± 105, 18 ± 5, 119 ± 47, and 69 ± 19 seconds, respectively. Average segmentation quality was 3.9 ± 0.2, 3.8 ± 0.3, and 3.8 ± 0.2 for LA, esophagus, and CS, respectively. Registration accuracy between the EAM and CE-CT-derived segmentation was 4.2 ± 0.9 mm. Complications consisted of one perforation (1%) which required pericardiocentesis, one increased pericardial effusion treated conservatively (1%), and one early termination of ablation due to thrombus formation on the ablation sheath without TIA/stroke (1%). All targeted PVs (n  =  309) were successfully isolated. The novel CT- CARTOSEG™ CT Segmentation Module enables a rapid and reliable semiautomatic 3D reconstruction of cardiac chambers and adjacent anatomy, which facilitates successful and safe PVI. © 2017 Wiley Periodicals, Inc.

Linkages between the South and East Asian summer monsoons: a review and revisit

NASA Astrophysics Data System (ADS)

Ha, Kyung-Ja; Seo, Ye-Won; Lee, June-Yi; Kripalani, R. H.; Yun, Kyung-Sook

2017-07-01

The relationship between the South Asia monsoon (SAM) and the East Asia monsoon (EAM) possibly modulated by both external forcings and internal dynamics has been a long-standing and controversial issue in climate sciences. This study reviews their linkages as revealed in modern records and model simulations during the past, present and future, and provides a comprehensive explanation of the key mechanisms controlling the diversity of the SAM-EAM relationship. Particular attention is paid to several external forcings that modulate the relationship, including El Niño and Southern Oscillation, Indian Ocean Dipole mode (IODM), boreal summer teleconnections, and Eurasian snow extent on intraseasonal to interdecadal timescales. The major focus is placed on two integral views of the inter-connection between the two monsoon systems: one is the positive inter-correlation, which is associated with decaying El Niño and developing Indian Ocean sea surface temperature (SST) warming anomalies; the other is the negative inter-correlation, resulting from developing El Niño and western Pacific SST cooling. The IODM mode also has a delayed impact on the negative connection by modulating Eurasian snow cover. The observed evidence reveals that the recent intensification of the negative relationship is attributable to the strengthening of the zonal SST gradient along the Indian Ocean, western Pacific, and eastern Pacific. Analysis of experiments in the fifth phase of the Coupled Model Intercomparison Project further indicates a possibility for the negative linkage to be further enhanced under anthropogenic global warming with considerable interdecadal modulation in mid and late twenty-first century.

Optoelectronic device physics and technology of nitride semiconductors from the UV to the terahertz.

PubMed

Moustakas, Theodore D; Paiella, Roberto

2017-10-01

This paper reviews the device physics and technology of optoelectronic devices based on semiconductors of the GaN family, operating in the spectral regions from deep UV to Terahertz. Such devices include LEDs, lasers, detectors, electroabsorption modulators and devices based on intersubband transitions in AlGaN quantum wells (QWs). After a brief history of the development of the field, we describe how the unique crystal structure, chemical bonding, and resulting spontaneous and piezoelectric polarizations in heterostructures affect the design, fabrication and performance of devices based on these materials. The heteroepitaxial growth and the formation and role of extended defects are addressed. The role of the chemical bonding in the formation of metallic contacts to this class of materials is also addressed. A detailed discussion is then presented on potential origins of the high performance of blue LEDs and poorer performance of green LEDs (green gap), as well as of the efficiency reduction of both blue and green LEDs at high injection current (efficiency droop). The relatively poor performance of deep-UV LEDs based on AlGaN alloys and methods to address the materials issues responsible are similarly addressed. Other devices whose state-of-the-art performance and materials-related issues are reviewed include violet-blue lasers, 'visible blind' and 'solar blind' detectors based on photoconductive and photovoltaic designs, and electroabsorption modulators based on bulk GaN or GaN/AlGaN QWs. Finally, we describe the basic physics of intersubband transitions in AlGaN QWs, and their applications to near-infrared and terahertz devices.

Optoelectronic device physics and technology of nitride semiconductors from the UV to the terahertz

NASA Astrophysics Data System (ADS)

Moustakas, Theodore D.; Paiella, Roberto

2017-10-01

This paper reviews the device physics and technology of optoelectronic devices based on semiconductors of the GaN family, operating in the spectral regions from deep UV to Terahertz. Such devices include LEDs, lasers, detectors, electroabsorption modulators and devices based on intersubband transitions in AlGaN quantum wells (QWs). After a brief history of the development of the field, we describe how the unique crystal structure, chemical bonding, and resulting spontaneous and piezoelectric polarizations in heterostructures affect the design, fabrication and performance of devices based on these materials. The heteroepitaxial growth and the formation and role of extended defects are addressed. The role of the chemical bonding in the formation of metallic contacts to this class of materials is also addressed. A detailed discussion is then presented on potential origins of the high performance of blue LEDs and poorer performance of green LEDs (green gap), as well as of the efficiency reduction of both blue and green LEDs at high injection current (efficiency droop). The relatively poor performance of deep-UV LEDs based on AlGaN alloys and methods to address the materials issues responsible are similarly addressed. Other devices whose state-of-the-art performance and materials-related issues are reviewed include violet-blue lasers, ‘visible blind’ and ‘solar blind’ detectors based on photoconductive and photovoltaic designs, and electroabsorption modulators based on bulk GaN or GaN/AlGaN QWs. Finally, we describe the basic physics of intersubband transitions in AlGaN QWs, and their applications to near-infrared and terahertz devices.

78 FR 66353 - EAM Nelson Holdings, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-05

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-2349-000] EAM Nelson Holdings, LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding, of EAM Nelson...

Therapy with granulocyte colony-stimulating factor in the chronic stage, but not in the acute stage, improves experimental autoimmune myocarditis in rats via nitric oxide.

PubMed

Shimada, Kana; Okabe, Taka-aki; Mikami, Yu; Hattori, Miki; Fujita, Masatoshi; Kishimoto, Chiharu

2010-09-01

We systematically investigated serial efficacy of granulocyte colony-stimulating factor (G-CSF) therapy upon experimental autoimmune myocarditis (EAM) in rats treated with and without the inhibition of nitric oxide (NO) with the analyses of tissue regeneration. G-CSF could mobilize multipotent progenitor cells of bone marrow into the peripheral blood and may improve ventricular function. A rat model of porcine myosin-induced EAM was used. After the immunization of myosin, G-CSF (10 microg/kg/day) or saline was injected intraperitoneally on days 0-21 in experiment 1 and on days 21-42 in experiment 2. Additional myosin-immunized rats were orally given 25 mg/kg/day of N(G)-nitro-L-arginine methylester (L-NAME), an inhibitor of nitric oxide synthase (NOS), in each experiment (each group; n=8-21). Serum cytokines and peripheral blood cell counts were measured in each group. In experiment 1, G-CSF treatment aggravated cardiac pathology associated with increased macrophage inflammatory protein-2 (MIP-2) and interleukin-6 (IL-6) levels and enhanced superoxide production. In experiment 2, G-CSF treatment reduced the severity of myocarditis with increased capillary density and improved left ventricular ejection fraction. In the rats with EAM treated with G-CSF associated with oral L-NAME treatment in experiment 2, the severity of myocarditis was not reduced. Myocardial c-kit(+) cells were demonstrated only in G-CSF-treated group in experiment 2 but not in other groups. G-CSF has differential effects on EAM in rats associated with the modulation of cytokine network. The overwhelming superoxide production by G-CSF administration in the acute stage may worsen the disease. G-CSF therapy improved cardiac function via NO system in a rat model of myocarditis in the chronic stage, but not in the acute stage, possibly through the myocardial regeneration and acceleration of healing process. Copyright 2010 Elsevier Ltd. All rights reserved.

Northward extent of East Asian monsoon covaries with intensity on orbital and millennial timescales.

PubMed

Goldsmith, Yonaton; Broecker, Wallace S; Xu, Hai; Polissar, Pratigya J; deMenocal, Peter B; Porat, Naomi; Lan, Jianghu; Cheng, Peng; Zhou, Weijian; An, Zhisheng

2017-02-21

The magnitude, rate, and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. Here, late Pleistocene-Holocene EAM rainfall intensity is reconstructed using a well-dated northeastern China closed-basin lake area record located at the modern northwestern fringe of the EAM. The EAM intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early and middle Holocene, requiring a twofold increase in annual rainfall, which, based on modern rainfall distribution, requires a ∼400 km northward expansion/migration of the EAM. The lake record is highly correlated with both northern and southern Chinese cave deposit isotope records, supporting rainfall "intensity based" interpretations of these deposits as opposed to an alternative "water vapor sourcing" interpretation. These results indicate that EAM intensity and the northward extent covary on orbital and millennial timescales. The termination of wet conditions at 5.5 ka BP (∼35 m lake drop) triggered a large cultural collapse of Early Neolithic cultures in north China, and possibly promoted the emergence of complex societies of the Late Neolithic.

Northward extent of East Asian monsoon covaries with intensity on orbital and millennial timescales

PubMed Central

Goldsmith, Yonaton; Broecker, Wallace S.; Xu, Hai; Polissar, Pratigya J.; deMenocal, Peter B.; Porat, Naomi; Lan, Jianghu; Cheng, Peng; Zhou, Weijian; An, Zhisheng

2017-01-01

The magnitude, rate, and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. Here, late Pleistocene–Holocene EAM rainfall intensity is reconstructed using a well-dated northeastern China closed-basin lake area record located at the modern northwestern fringe of the EAM. The EAM intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early and middle Holocene, requiring a twofold increase in annual rainfall, which, based on modern rainfall distribution, requires a ∼400 km northward expansion/migration of the EAM. The lake record is highly correlated with both northern and southern Chinese cave deposit isotope records, supporting rainfall “intensity based” interpretations of these deposits as opposed to an alternative “water vapor sourcing” interpretation. These results indicate that EAM intensity and the northward extent covary on orbital and millennial timescales. The termination of wet conditions at 5.5 ka BP (∼35 m lake drop) triggered a large cultural collapse of Early Neolithic cultures in north China, and possibly promoted the emergence of complex societies of the Late Neolithic. PMID:28167754

Northward extent of East Asian monsoon covaries with intensity on orbital and millennial timescales

NASA Astrophysics Data System (ADS)

Goldsmith, Yonaton; Broecker, Wallace S.; Xu, Hai; Polissar, Pratigya J.; deMenocal, Peter B.; Porat, Naomi; Lan, Jianghu; Cheng, Peng; Zhou, Weijian; An, Zhisheng

2017-02-01

The magnitude, rate, and extent of past and future East Asian monsoon (EAM) rainfall fluctuations remain unresolved. Here, late Pleistocene-Holocene EAM rainfall intensity is reconstructed using a well-dated northeastern China closed-basin lake area record located at the modern northwestern fringe of the EAM. The EAM intensity and northern extent alternated rapidly between wet and dry periods on time scales of centuries. Lake levels were 60 m higher than present during the early and middle Holocene, requiring a twofold increase in annual rainfall, which, based on modern rainfall distribution, requires a ˜400 km northward expansion/migration of the EAM. The lake record is highly correlated with both northern and southern Chinese cave deposit isotope records, supporting rainfall “intensity based” interpretations of these deposits as opposed to an alternative “water vapor sourcing” interpretation. These results indicate that EAM intensity and the northward extent covary on orbital and millennial timescales. The termination of wet conditions at 5.5 ka BP (˜35 m lake drop) triggered a large cultural collapse of Early Neolithic cultures in north China, and possibly promoted the emergence of complex societies of the Late Neolithic.

Nanoparticle-based biosensor for the detection of emerging pandemic influenza strains.

PubMed

Kamikawa, Tracy L; Mikolajczyk, Malgorzata G; Kennedy, Michael; Zhang, Pei; Wang, Wei; Scott, Dorothy E; Alocilja, Evangelyn C

2010-12-15

Electrically active magnetic (EAM) nanoparticles, consisting of aniline monomer polymerized around gamma iron(III) oxide (γ-Fe(2)O(3)) cores, serve as the basis of a direct-charge transfer biosensor developed for detection of surface glycoprotein hemagglutinin (HA) from the Influenza A virus (FLUAV) H5N1 (A/Vietnam/1203/04). H5N1 preferentially binds α2,3-linked host glycan receptors. EAM nanoparticles were immunofunctionalized with antibodies against target HA. Glycans preincubated with HA in 10% mouse serum were incubated with anti-HA-EAM complexes. The anti-HA-EAM complexes effectively acted as immunomagnetic separator of HA from mouse serum matrix. EAM nanoparticles served as the biosensor transducer for cyclic voltammetry measurements. The polyaniline was made electrically active by hydrochloric acid doping. Experimental results indicate that the biosensor is able to detect recombinant H5 HA at 1.4 μM in 10% mouse serum, with high specificity for H5 as compared to H1 (H1N1 A/South Carolina/1/18). This novel design applies EAM nanoparticles in a sensitive, specific, affordable, and easy-to-use biosensor with applications in disease monitoring and biosecurity. Copyright © 2010 Elsevier B.V. All rights reserved.

RF Photonic Technology in Optical Fiber Links

NASA Astrophysics Data System (ADS)

Chang, William S. C.

2007-06-01

List of contributors; Introduction and preface; 1. Figures of merit and performance analysis of photonic microwave links Charles Cox and William S. C. Chang; 2. RF subcarrier links in local access networks Xiaolin Lu; 3. Analog modulation of semiconductor lasers Joachim Piprek and John E. Bowers; 4. LiNbO3 external modulators and their use in high performance analog links Gary E. Betts; 5. Broadband traveling wave modulators in LiNbO3 Marta M. Howerton and William K. Burns; 6. Multiple quantum well electroabsorption modulators for RF photonic links William S. C. Chang; 7. Polymer modulators for RF photonics Timothy Van Eck; 8. Photodiodes for high performance analog links P. K. L. Yu and Ming C. Wu; 9. Opto-electronic oscillators X. Steve Yao; 10. Photonic link techniques for microwave frequency conversion Stephen A. Pappert, Roger Helkey and Ronald T. Logan Jr; 11. Antenna-coupled millimeter-wave electro-optical modulators William B. Bridges; 12. System design and performance of wideband photonic phased array antennas Greg L. Tangonan, Willie Ng, Daniel Yap and Ron Stephens; Acknowledgements; References; Index.

Flattened optical frequency-locked multi-carrier generation by cascading one EML and one phase modulator driven by different RF clocks

NASA Astrophysics Data System (ADS)

Li, Xinying; Xiao, Jiangnan

2015-06-01

We propose a novel scheme for optical frequency-locked multi-carrier generation based on one electro-absorption modulated laser (EML) and one phase modulator (PM) in cascade driven by different sinusoidal radio-frequency (RF) clocks. The optimal operating zone for the cascaded EML and PM is found out based on theoretical analysis and numerical simulation. We experimentally demonstrate 25 optical subcarriers with frequency spacing of 12.5 GHz and power difference less than 5 dB can be generated based on the cascaded EML and PM operating in the optimal zone, which agrees well with the numerical simulation. We also experimentally demonstrate 28-Gbaud polarization division multiplexing quadrature phase shift keying (PDM-QPSK) modulated coherent optical transmission based on the cascaded EML and PM. The bit error ratio (BER) can be below the pre-forward-error-correction (pre-FEC) threshold of 3.8 × 10-3 after 80-km single-mode fiber-28 (SMF-28) transmission.

Treatment and prevention of experimental autoimmune myocarditis with CD28 superagonists.

PubMed

Wang, Shu; Liu, Jing; Wang, Min; Zhang, Jinghui; Wang, Zhaohui

2010-01-01

Experimental autoimmune myocarditis (EAM), a rodent model of human dilated cardiomyopathy (DCM), is mediated by an autoimmune mechanism. We investigated whether a CD28 superagonistic antibody selectively targeting CD4+CD25+ regulatory T cells (T(regs)) provides effective therapy for EAM. Four groups of 5 rats were used. The normal control group was immunized with PBS. The EAM group was immunized with porcine myosin. The experimental group was immunized with myosin and superagonistic CD28 antibody JJ316. The final group was immunized with myosin and an unrelated rat IgG. Autoantibody and IL-10 production, CD4+CD25+ cell levels, Foxp3 expression and cardiac histology were analyzed. Anti-myosin autoantibody levels were higher in the EAM and isotype control groups than the normal control group (p < 0.05), and reduced in the CD28-JJ316 group (p < 0.05). The levels of CD25+CD4+ cells, IL-10 and splenocyte Foxp3 expression were significantly lower in the EAM and isotype control groups versus the CD28-JJ316 group (p < 0.05). Infiltration of inflammatory cells was observed in the EAM and isotype control groups, whereas CD28-JJ316 ameliorated myocarditis. CD28 superagonists could be effective in EAM treatment by up-regulating Foxp3 expression and contributing to CD4+CD25+ T(reg) activation and expansion. The enhancement in IL-10 by CD28 superagonists also ameliorated the disease.

Metagenomic insights into the ecology and physiology of microbes in bioelectrochemical systems.

PubMed

Kouzuma, Atsushi; Ishii, Shun'ichi; Watanabe, Kazuya

2018-05-01

In bioelectrochemical systems (BESs), electrons are transferred between electrochemically active microbes (EAMs) and conductive materials, such as electrodes, via extracellular electron transfer (EET) pathways, and electrons thus transferred stimulate intracellular catabolic reactions. Catabolic and EET pathways have extensively been studied for several model EAMs, such as Shewanella oneidensis MR-1 and Geobacter sulfurreducens PCA, whereas it is also important to understand the ecophysiology of EAMs in naturally occurring microbiomes, such as those in anode biofilms in microbial fuel cells treating wastewater. Recent studies have exploited metagenomics and metatranscriptomics (meta-omics) approaches to characterize EAMs in BES-associated microbiomes. Here we review recent BES studies that used meta-omics approaches and show that these studies have discovered unexpected features of EAMs and deepened our understanding of functions and behaviors of microbes in BESs. It is desired that more studies will employ meta-omics approaches for advancing our knowledge on microbes in BESs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Arrhythmia Mechanism and Scaling Effect on the Spectral Properties of Electroanatomical Maps With Manifold Harmonics.

PubMed

Sanroman-Junquera, Margarita; Mora-Jimenez, Inmaculada; Garcia-Alberola, Arcadio; Caamano, Antonio J; Trenor, Beatriz; Rojo-Alvarez, Jose L

2018-04-01

Spatial and temporal processing of intracardiac electrograms provides relevant information to support the arrhythmia ablation during electrophysiological studies. Current cardiac navigation systems (CNS) and electrocardiographic imaging (ECGI) build detailed 3-D electroanatomical maps (EAM), which represent the spatial anatomical distribution of bioelectrical features, such as activation time or voltage. We present a principled methodology for spectral analysis of both EAM geometry and bioelectrical feature in CNS or ECGI, including their spectral representation, cutoff frequency, or spatial sampling rate (SSR). Existing manifold harmonic techniques for spectral mesh analysis are adapted to account for a fourth dimension, corresponding to the EAM bioelectrical feature. Appropriate scaling is required to address different magnitudes and units. With our approach, simulated and real EAM showed strong SSR dependence on both the arrhythmia mechanism and the cardiac anatomical shape. For instance, high frequencies increased significantly the SSR because of the "early-meets-late" in flutter EAM, compared with the sinus rhythm. Besides, higher frequency components were obtained for the left atrium (more complex anatomy) than for the right atrium in sinus rhythm. The proposed manifold harmonics methodology opens the field toward new signal processing tools for principled EAM spatiofeature analysis in CNS and ECGI, and to an improved knowledge on arrhythmia mechanisms.

Holocene East Asian Monsoon Variability: Links to Solar and Tropical Pacific Forcing

NASA Astrophysics Data System (ADS)

Kandasamy, S.; Chen, C. A.; Lou, J.

2006-12-01

Sedimentary geochemical records from subalpine Retreat Lake, subtropical Taiwan, document the unstable East Asian Monsoon (EAM) climate for the last ~10250 calendar years before the present (cal yr B.P.). The proxy records demonstrate cool, glacial conditions with weak EAM between ~10250 and 8640 cal yr B.P., the strongest EAM during the "Holocene optimum" (8640-4500 cal yr B.P.) with an abrupt, decadal onset of postglacial EAM (8640-8600 cal yr B.P.), and relatively dry conditions since 4500 cal yr B.P. Although after 8600 cal yr B.P., EAM strength reduces gradually in response to the Northern Hemisphere summer insolation, heat and moisture transport and the development of late Holocene El-Niño-Southern Oscillation in the tropical Pacific appear to corroborate the periods of abrupt monsoon changes. Our proxy records reveal several weak monsoon intervals that correlate to low sea surface temperatures in the western tropical Pacific and cold events in the North Atlantic, suggesting a mechanistic link. Among those, four weak EAM events at 8170, 5400, 4500-2100 and 2000-1600 cal yr B.P. are in phase with the timings of low concentrations of atmospheric methane and periods of reduced North Atlantic Deep Water production as well as the `8.2 ka cold spell' and widespread event of low-latitude cultural collapse. Our EAM records exhibit strong correlations with high- and low-latitude climate and monsoon records; thus, provide robust evidences that the centennial-millennial scale monsoon variability during the Holocene are globally-mediated via sun- ocean-monsoon-North Atlantic linkages.

Objective characterization of airway dimensions using image processing.

PubMed

Pepper, Victoria K; Francom, Christian; Best, Cameron A; Onwuka, Ekene; King, Nakesha; Heuer, Eric; Mahler, Nathan; Grischkan, Jonathan; Breuer, Christopher K; Chiang, Tendy

2016-12-01

With the evolution of medical and surgical management for pediatric airway disorders, the development of easily translated techniques of measuring airway dimensions can improve the quantification of outcomes of these interventions. We have developed a technique that improves the ability to characterize endoscopic airway dimensions using common bronchoscopic equipment and an open-source image-processing platform. We validated our technique of Endoscopic Airway Measurement (EAM) using optical instruments in simulation tracheas. We then evaluated EAM in a large animal model (Ovis aries, n = 5), comparing tracheal dimensions obtained with EAM to measurements obtained via 3-D fluoroscopic reconstruction. The animal then underwent resection of the measured segment, and direct measurement of this segment was performed and compared to radiographic measurements and those obtained using EAM. The simulation tracheas had a direct measurement of 13.6, 18.5, and 24.2 mm in diameter. The mean difference of diameter in simulation tracheas between direct measurements and measurements obtained using EAM was 0.70 ± 0.57 mm. The excised ovine tracheas had an average diameter of 18.54 ± 0.68 mm. The percent difference in diameter obtained from EAM and from 3-D fluoroscopic reconstruction when compared to measurement of the excised tracheal segment was 4.98 ± 2.43% and 10.74 ± 4.07% respectively. Comparison of these three measurements (EAM, measurement of resected trachea, 3-D fluoroscopic reconstruction) with repeated measures ANOVA demonstrated no statistical significance. Endoscopic airway measurement (EAM) provides equivalent measurements of the airway with the improved versatility of measuring non-circular and multi-level dimensions. Using optical bronchoscopic instruments and open-source image-processing software, our data supports preclinical and clinical translation of an accessible technique to provide objective quantification of airway diameter. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The oscillating fringe and paleo-intensity of the East Asian monsoon reconstructed using closed-basin lake-area and dDwax

NASA Astrophysics Data System (ADS)

Goldsmith, Y.; Broecker, W. S.; Polissar, P. J.; Xu, H.; Lan, J.; Zhou, W.; An, Z.; deMenocal, P. B.

2016-12-01

The magnitude, rate and extent of East Asian Monsoon (EAM) rainfall changes during the late Pleistocene-Holocene is reconstructed using the first well-dated northeastern China lake-area record from a closed-lake basin, which enables reconstructing quantitative absolute paleo-rainfall amounts. In addition, compound specific hydrogen isotopes (dDwax) from lake-sediments are used to reconstruct the isotopic composition of rainwater (dP). Lake-levels were 60m higher than present during the early and middle Holocene. Requiring an absolute increase in mean annual rainfall to at least two times higher than today and a 400 km northward expansion. The EAM intensity and northern extent alternated abruptly between wet and dry periods on time scales of a few centuries. Both the onset ( 60 m rise at 11.5 ka BP) and termination ( 35 m drop at 5.5 ka BP) of the Holocene humid period occurred abruptly, within centuries. dDwax is negatively correlated with the lake area record (R2=0.77), showing for the first time, the co-evolution of dP and local rainfall amount. Lake level is also highly correlated with Both North and South Chinese stalagmite records. These results indicate that local distillation is a significant control on dP in East China, and that local rainfall amount is correlated with the intensity of the large EAM system. These results resolve a current debate regarding the use of dP as a proxy for rainfall amount and validate the "intensity-based" interpretations of the Chinese cave deposit records. The lake is located at the modern NW boundary of the EAM, therefore, lake level is governed by the northward extent of the EAM. The covariation of lake level and the intensity of the monsoon indicate that intensity and northward expansion of the EAM are linked and that during intense (weak) EAM periods the EAM northwestern boundary shifts northward (southward).

Field-modulation spectroscopy of pentacene thin films using field-effect devices: Reconsideration of the excitonic structure

NASA Astrophysics Data System (ADS)

Haas, Simon; Matsui, Hiroyuki; Hasegawa, Tatsuo

2010-10-01

We report pure electric-field effects on the excitonic absorbance of pentacene thin films as measured by unipolar field-effect devices that allowed us to separate the charge accumulation effects. The field-modulated spectra between 1.8 and 2.6 eV can be well fitted with the first derivative curve of Frenkel exciton absorption and its vibronic progression, and at higher energy a field-induced feature appears at around 2.95 eV. The results are in sharp contrast to the electroabsorption spectra reported by Sebastian in previous studies [Chem. Phys. 61, 125 (1981)10.1016/0301-0104(81)85055-0], and leads us to reconsider the excitonic structure including the location of charge-transfer excitons. Nonlinear π -electronic response is discussed based on second-order electro-optic (Kerr) spectra.

Complete Freund's adjuvant induces experimental autoimmune myocarditis by enhancing IL-6 production during initiation of the immune response.

PubMed

Fontes, Jillian A; Barin, Jobert G; Talor, Monica V; Stickel, Natalie; Schaub, Julie; Rose, Noel R; Čiháková, Daniela

2017-06-01

Complete Freund's Adjuvant (CFA) emulsified with an antigen is a widely used method to induce autoimmune disease in animal models, yet the contribution of CFA to the immune response is not well understood. We compared the effectiveness of CFA with Incomplete Freund's Adjuvant (IFA) or TiterMax Gold Adjuvant (TMax) in experimental autoimmune myocarditis (EAM) in male mice. EAM was induced in A/J, BALB/c, and IL6KO BALB/c male mice by injection of the myocarditogenic peptide in CFA, IFA, or TMax on days 0 and 7. EAM severity was analyzed by histology on day 21. In addition, specific flow cytometry outcomes were evaluated on day 21. Only mice immunized with CFA and myocarditogenic peptide on both days 0 and 7 developed substantial myocarditis as measured by histology. We observed a significantly increased level of IL6 in the spleen 3 days after CFA immunization. In the spleen and heart on day 21, there was an expansion of myeloid cells in CFA-immunized mice, as compared to IFA or TMax-immunized animals. Recombinant IL-6 at the time of IFA immunization partially restored susceptibility of the mice to EAM. We also treated EAM-resistant IL-6 knockout mice with recombinant IL-6 around the time of the first immunization, on days -1 to 2, completely restoring disease susceptibility, showing that the requirement for IL-6 coincides with primary immunization. Examining APC populations in the lymph node draining the immunization site evidenced the contribution of IL-6 to the CFA-dependence of EAM was through controlling local dendritic cell (DC) trafficking. CFA used with myocarditogenic peptide twice is required to induce EAM in both A/J and Balb/c mice. Although IFA and TiterMax induce antibody responses, only CFA preferentially induced autoantigen-specific responses. CFA expands monocytes in the heart and in the spleen. IL-6 signaling is required during short window around primary immunization to induce EAM. In addition, IL-6 deficient mice resistance to EAM could be reversed by injecting IL-6 around first immunization. IL-6 expands dendritic cell and monocytic populations and ultimately leads to a robust T-cell driven immune response in CFA immunized mice. © 2017 The Authors. Immunity, Inflammation and Disease Published by John Wiley & Sons Ltd.

Emerging technologies in Si active photonics

NASA Astrophysics Data System (ADS)

Wang, Xiaoxin; Liu, Jifeng

2018-06-01

Silicon photonics for synergistic electronic–photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent progress towards efficient monolithic Ge lasers, mid-infrared GeSn lasers, and high-performance InAs quantum dot lasers on Si for data center applications in the near future. We will then review novel modulator materials and devices beyond the free carrier plasma dispersion effect in Si, including GeSi and graphene electro-absorption modulators and plasmonic-organic electro-optical modulators, to achieve ultralow power and high speed modulation. Finally, we discuss emerging photodetectors beyond epitaxial Ge p–i–n photodiodes, including GeSn mid-infrared photodetectors, all-Si plasmonic Schottky infrared photodetectors, and Si quanta image sensors for non-avalanche, low noise single photon detection and photon counting. These emerging technologies, though still under development, could make a significant impact on the future of large-scale electronicSilicon photonics for synergistic electronic-photonic integration has achieved remarkable progress in the past two decades. Active photonic devices, including lasers, modulators, and photodetectors, are the key challenges for Si photonics to meet the requirement of high bandwidth and low power consumption in photonic datalinks. Here we review recent efforts and progress in high-performance active photonic devices on Si, focusing on emerging technologies beyond conventional foundry-ready Si photonics devices. For emerging laser sources, we will discuss recent progress towards efficient monolithic Ge lasers, mid-infrared GeSn lasers, and high-performance InAs quantum dot lasers on Si for data center applications in the near future. We will then review novel modulator materials and devices beyond the free carrier plasma dispersion effect in Si, including GeSi and graphene electro-absorption modulators and plasmonic-organic electro–optical modulators, to achieve ultralow power and high speed modulation. Finally, we discuss emerging photodetectors beyond epitaxial Ge p–i–n photodiodes, including GeSn mid-infrared photodetectors, all-Si plasmonic Schottky infrared photodetectors, and Si quanta image sensors for non-avalanche, low noise single photon detection and photon counting. These emerging technologies, though still under development, could make a significant impact on the future of large-scale electronic–photonic integration with performance inaccessible from conventional Si photonics technologies-photonic integration with performance inaccessible from conventional Si photonics technologies.

Graphene optical modulator

NASA Astrophysics Data System (ADS)

Liu, Ming; Yin, Xiaobo; Wang, Feng; Zhang, Xiang

2011-10-01

Data communications have been growing at a speed even faster than Moore's Law, with a 44-fold increase expected within the next 10 years. Data Transfer on such scale would have to recruit optical communication technology and inspire new designs of light sources, modulators, and photodetectors. An ideal optical modulator will require high modulation speed, small device footprint and large operating bandwidth. Silicon modulators based on free carrier plasma dispersion effect and compound semiconductors utilizing direct bandgap transition have seen rapid improvement over the past decade. One of the key limitations for using silicon as modulator material is its weak refractive index change, which limits the footprint of silicon Mach-Zehnder interferometer modulators to millimeters. Other approaches such as silicon microring modulators reduce the operation wavelength range to around 100 pm and are highly sensitive to typical fabrication tolerances and temperature fluctuations. Growing large, high quality wafers of compound semiconductors, and integrating them on silicon or other substrates is expensive, which also restricts their commercialization. In this work, we demonstrate that graphene can be used as the active media for electroabsorption modulators. By tuning the Fermi energy level of the graphene layer, we induced changes in the absorption coefficient of graphene at communication wavelength and achieve a modulation depth above 3 dB. This integrated device also has the potential of working at high speed.

The Effect of Prosthetic Foot Push-off on Mechanical Loading Associated with Knee Osteoarthritis in Lower Extremity Amputees

PubMed Central

Morgenroth, David C.; Segal, Ava D.; Zelik, Karl E.; Czerniecki, Joseph M.; Klute, Glenn K.; Adamczyk, Peter G.; Orendurff, Michael S.; Hahn, Michael E.; Collins, Steven H.; Kuo, Art D.

2011-01-01

Lower extremity amputation not only limits mobility, but also increases the risk of knee osteoarthritis of the intact limb. Dynamic walking models of non-amputees suggest that pushing-off from the trailing limb can reduce collision forces on the leading limb. These collision forces may determine the peak knee external adduction moment (EAM), which has been linked to the development of knee OA in the general population. We therefore hypothesized that greater prosthetic push-off would lead to reduced loading and knee EAM of the intact limb in unilateral transtibial amputees. Seven unilateral transtibial amputees were studied during gait under three prosthetic foot conditions that were intended to vary push-off. Prosthetic foot-ankle push-off work, intact limb knee EAM and ground reaction impulses for both limbs during step-to-step transition were measured. Overall, trailing limb prosthetic push-off work was negatively correlated with leading intact limb 1st peak knee EAM (slope = −0.72 +/− 0.22; p=0.011). Prosthetic push-off work and 1st peak intact knee EAM varied significantly with foot type. The prosthetic foot condition with the least push-off demonstrated the largest knee EAM, which was reduced by 26% with the prosthetic foot producing the most push-off. Trailing prosthetic limb push-off impulse was negatively correlated with leading intact limb loading impulse (slope = −0.34 +/− 0.14; p=.001), which may help explain how prosthetic limb push-off can affect intact limb loading. Prosthetic feet that perform more prosthetic push-off appear to be associated with a reduction in 1st peak intact knee EAM, and their use could potentially reduce the risk and burden of knee osteoarthritis in this population. PMID:21803584

Patterns of hippocampal-neocortical interactions in the retrieval of episodic autobiographical memories across the entire life-span of aged adults

PubMed Central

Viard, Armelle; Lebreton, Karine; Chételat, Gaël; Desgranges, Béatrice; Landeau, Brigitte; Young, Alan; De La Sayette, Vincent; Eustache, Francis; Piolino, Pascale

2010-01-01

We previously demonstrated that Episodic Autobiographical Memories (EAMs) rely on a network of brain regions comprising the medial temporal lobe (MTL) and distributed neocortical regions regardless of their remoteness. The findings supported the model of memory consolidation which proposes a permanent role of MTL during EAM retrieval (Multiple-Trace Theory or MTT) rather than a temporary role (standard model). Our present aim was to expand the results by examining the interactions between the MTL and neocortical regions (or MTL-neocortical links) during EAM retrieval with varying retention intervals. We used an experimental paradigm specially designed to engage aged participants in the recollection of EAMs, extracted from five different time-periods, covering their whole life-span, in order to examine correlations between activation in the MTL and neocortical regions. The nature of the memories was checked at debriefing by means of behavioral measures to control the degree of episodicity and properties of memories. Targeted correlational analyses carried out on the MTL, frontal, lateral temporal and posterior regions revealed strong links between the MTL and neocortex during the retrieval of both recent and remote EAMs, challenging the standard model of memory consolidation and supporting MTT instead. Further confirmation was given by results showing that activation in the left and right hippocampi significantly correlated during the retrieval of both recent and remote memories. Correlations among extra-MTL neocortical regions also emerged for all time-periods, confirming the critical role of the prefrontal, temporal (lateral temporal cortex and temporal pole), precuneus and posterior cingulate regions in EAM retrieval. Overall, this paper emphasizes the role of a bilateral network of MTL and neocortical areas whose activation correlate during the recollection of rich phenomenological recent and remote EAMs. PMID:19338022

The effect of prosthetic foot push-off on mechanical loading associated with knee osteoarthritis in lower extremity amputees.

PubMed

Morgenroth, David C; Segal, Ava D; Zelik, Karl E; Czerniecki, Joseph M; Klute, Glenn K; Adamczyk, Peter G; Orendurff, Michael S; Hahn, Michael E; Collins, Steven H; Kuo, Art D

2011-10-01

Lower extremity amputation not only limits mobility, but also increases the risk of knee osteoarthritis of the intact limb. Dynamic walking models of non-amputees suggest that pushing-off from the trailing limb can reduce collision forces on the leading limb. These collision forces may determine the peak knee external adduction moment (EAM), which has been linked to the development of knee OA in the general population. We therefore hypothesized that greater prosthetic push-off would lead to reduced loading and knee EAM of the intact limb in unilateral transtibial amputees. Seven unilateral transtibial amputees were studied during gait under three prosthetic foot conditions that were intended to vary push-off. Prosthetic foot-ankle push-off work, intact limb knee EAM and ground reaction impulses for both limbs during step-to-step transition were measured. Overall, trailing limb prosthetic push-off work was negatively correlated with leading intact limb 1st peak knee EAM (slope=-.72±.22; p=.011). Prosthetic push-off work and 1st peak intact knee EAM varied significantly with foot type. The prosthetic foot condition with the least push-off demonstrated the largest knee EAM, which was reduced by 26% with the prosthetic foot producing the most push-off. Trailing prosthetic limb push-off impulse was negatively correlated with leading intact limb loading impulse (slope=-.34±.14; p=.001), which may help explain how prosthetic limb push-off can affect intact limb loading. Prosthetic feet that perform more prosthetic push-off appear to be associated with a reduction in 1st peak intact knee EAM, and their use could potentially reduce the risk and burden of knee osteoarthritis in this population. Published by Elsevier B.V.

Prospective randomized comparison of rotational angiography with three-dimensional reconstruction and computed tomography merged with electro-anatomical mapping: a two center atrial fibrillation ablation study.

PubMed

Anand, Rishi; Gorev, Maxim V; Poghosyan, Hermine; Pothier, Lindsay; Matkins, John; Kotler, Gregory; Moroz, Sarah; Armstrong, James; Nemtsov, Sergei V; Orlov, Michael V

2016-08-01

To compare the efficacy and accuracy of rotational angiography with three-dimensional reconstruction (3DATG) image merged with electro-anatomical mapping (EAM) vs. CT-EAM. A prospective, randomized, parallel, two-center study conducted in 36 patients (25 men, age 65 ± 10 years) undergoing AF ablation (33 % paroxysmal, 67 % persistent) guided by 3DATG (group 1) vs. CT (group 2) image fusion with EAM. 3DATG was performed on the Philips Allura Xper FD 10 system. Procedural characteristics including time, radiation exposure, outcome, and navigation accuracy were compared between two groups. There was no significant difference between the groups in total procedure duration or time spent for various procedural steps. Minor differences in procedural characteristics were present between two centers. Segmentation and fusion time for 3DATG or CT-EAM was short and similar between both centers. Accuracy of navigation guided by either method was high and did not depend on left atrial size. Maintenance of sinus rhythm between the two groups was no different up to 24 months of follow-up. This study did not find superiority of 3DATG-EAM image merge to guide AF ablation when compared to CT-EAM fusion. Both merging techniques result in similar navigation accuracy.

Beneficial effects of edaravone, a novel antioxidant, in rats with dilated cardiomyopathy

PubMed Central

Arumugam, Somasundaram; Thandavarayan, Rajarajan A; Veeraveedu, Punniyakoti T; Nakamura, Takashi; Arozal, Wawaimuli; Sari, Flori R; Giridharan, Vijayasree V; Soetikno, Vivian; Palaniyandi, Suresh S; Harima, Meilei; Suzuki, Kenji; Nagata, Masaki; Kodama, Makoto; Watanabe, Kenichi

2012-01-01

Edaravone, a novel antioxidant, acts by trapping hydroxyl radicals, quenching active oxygen and so on. Its cardioprotective activity against experimental autoimmune myocarditis (EAM) was reported. Nevertheless, it remains to be determined whether edaravone protects against cardiac remodelling in dilated cardiomyopathy (DCM). The present study was undertaken to assess whether edaravone attenuates myocardial fibrosis, and examine the effect of edaravone on cardiac function in rats with DCM after EAM. Rat model of EAM was prepared by injection with porcine cardiac myosin 28 days after immunization, we administered edaravone intraperitoneally at 3 and 10 mg/kg/day to rats for 28 days. The results were compared with vehicle-treated rats with DCM. Cardiac function, by haemodynamic and echocardiographic study and histopathology were performed. Left ventricular (LV) expression of NADPH oxidase subunits (p47phox, p67phox, gp91phox and Nox4), fibrosis markers (TGF-β1 and OPN), endoplasmic reticulum (ER) stress markers (GRP78 and GADD 153) and apoptosis markers (cytochrome C and caspase-3) were measured by Western blotting. Edaravone-treated DCM rats showed better cardiac function compared with those of the vehicle-treated rats. In addition, LV expressions of NADPH oxidase subunits levels were significantly down-regulated in edaravone-treated rats. Furthermore, the number of collagen-III positive cells in the myocardium of edaravone-treated rats was lower compared with those of the vehicle-treated rats. Our results suggest that edaravone ameliorated the progression of DCM by modulating oxidative and ER stress-mediated myocardial apoptosis and fibrosis. PMID:22268705

Using an electronic activity monitor system as an intervention modality: A systematic review.

PubMed

Lewis, Zakkoyya H; Lyons, Elizabeth J; Jarvis, Jessica M; Baillargeon, Jacques

2015-06-24

Obesity is a growing global health concern that may lead to cardiovascular disease, type II diabetes, and cancer. Several systematic reviews have shown that technology is successful in combating obesity through increased physical activity, but there is no known review on interventions that use an electronic activity monitor system (EAMS). EAMSs are defined as a wearable device that objectively measures lifestyle physical activity and can provide feedback, beyond the display of basic activity count information, via the monitor display or through a partnering application to elicit continual self-monitoring of activity behavior. These devices improve upon standard pedometers because they have the ability to provide visual feedback on activity progression, verbal encouragement, and social comparison. This systematic review aimed to synthesize the efficacy and feasibility results of EAMSs within published physical activity interventions. Electronic databases and journal references were searched for relevant articles. Data sources included CINAHL, Cochrane CENTRAL, Medline Ovid, PsycINFO, and clinicaltrials.gov. Out of the 1,574 retrieved, 11 articles met the inclusion criteria. These articles were reviewed for quality and content based on a risk of bias tool and intervention components. Most articles were determined to be of medium quality while two were of low quality, and one of high quality. Significant pre-post improvements in the EAMS group were found in five of nine studies for physical activity and in four of five studies for weight. One found a significant increase in physical activity and two studies found significant weight loss in the intervention group compared with the comparator group. The EAMS interventions appear to be feasible with most studies reporting continual wear of the device during waking hours and a higher retention rate of participants in the EAMS groups. These studies provide preliminary evidence suggesting that EAMS can increase physical activity and decrease weight significantly, but their efficacy compared to other interventions has not yet been demonstrated. More high-quality randomized controlled trials are needed to evaluate the overall effect of EAMS, examine which EAMS features are most effective, and determine which populations are most receptive to an EAMS.

A novel simultaneous demultiplexing and clock recovery unit for high speed OTDM system

NASA Astrophysics Data System (ADS)

Zhong, Kangping; Jia, Nan; Li, Tangjun; Wang, Muguang; Chi, Jianfeng; Sun, Jian; Wang, Jingtian

2010-11-01

In this letter, a novel simultaneous demultiplexing and clock recovery unit based on EAMs and clock recovery module is presented and experimentally demonstrated for a high speed OTDM system. The 10GHz clock signal with low jitter is extracted from 80Gbit/s and 160Gbit/s OTDM signal, and every channel of the OTDM signal is successfully demultiplexed using this unit. The power penalty is lower than 3dB at BER of 10-9.

77 FR 14513 - Combined Notice of Filings #2

Federal Register 2010, 2011, 2012, 2013, 2014

2012-03-12

..., Northern Iowa Windpower, LLC, EAM Nelson Holding, LLC, EWO Marketing, LLC, Entergy Rhode Island State Energy, L.P. Description: Supplemental information of EAM Nelson Holding, LLC, et al. Filed Date: 03/02...

Predicting Earth orientation changes from global forecasts of atmosphere-hydrosphere dynamics

NASA Astrophysics Data System (ADS)

Dobslaw, Henryk; Dill, Robert

2018-02-01

Effective Angular Momentum (EAM) functions obtained from global numerical simulations of atmosphere, ocean, and land surface dynamics are routinely processed by the Earth System Modelling group at Deutsches GeoForschungsZentrum. EAM functions are available since January 1976 with up to 3 h temporal resolution. Additionally, 6 days-long EAM forecasts are routinely published every day. Based on hindcast experiments with 305 individual predictions distributed over 15 months, we demonstrate that EAM forecasts improve the prediction accuracy of the Earth Orientation Parameters at all forecast horizons between 1 and 6 days. At day 6, prediction accuracy improves down to 1.76 mas for the terrestrial pole offset, and 2.6 mas for Δ UT1, which correspond to an accuracy increase of about 41% over predictions published in Bulletin A by the International Earth Rotation and Reference System Service.

Embedded-atom-method interatomic potentials from lattice inversion.

PubMed

Yuan, Xiao-Jian; Chen, Nan-Xian; Shen, Jiang; Hu, Wangyu

2010-09-22

The present work develops a physically reliable procedure for building the embedded-atom-method (EAM) interatomic potentials for the metals with fcc, bcc and hcp structures. This is mainly based on Chen-Möbius lattice inversion (Chen et al 1997 Phys. Rev. E 55 R5) and first-principles calculations. Following Baskes (Baskes et al 2007 Phys. Rev. B 75 094113), this new version of the EAM eliminates all of the prior arbitrary choices in the determination of the atomic electron density and pair potential functions. Parameterizing the universal form deduced from the calculations within the density-functional scheme for homogeneous electron gas as the embedding function, the new-type EAM potentials for Cu, Fe and Ti metals have successfully been constructed by considering interatomic interactions up to the fifth neighbor, the third neighbor and the seventh neighbor, respectively. The predictions of elastic constants, structural energy difference, vacancy formation energy and migration energy, activation energy of vacancy diffusion, latent heat of melting and relative volume change on melting all satisfactorily agree with the experimental results available or first-principles calculations. The predicted surface energies for low-index crystal faces and the melting point are in agreement with the experimental data to the same extent as those calculated by other EAM-type potentials such as the FBD-EAM, 2NN MEAM and MS-EAM. In addition, the order among the predicted low-index surface energies is also consistent with the experimental information.

Broadband, Spectrally Flat, Graphene-based Terahertz Modulators.

PubMed

Shi, Fenghua; Chen, Yihang; Han, Peng; Tassin, Philippe

2015-12-02

Advances in the efficient manipulation of terahertz waves are crucial for the further development of terahertz technology, promising applications in many diverse areas, such as biotechnology and spectroscopy, to name just a few. Due to its exceptional electronic and optical properties, graphene is a good candidate for terahertz electro-absorption modulators. However, graphene-based modulators demonstrated to date are limited in bandwidth due to Fabry-Perot oscillations in the modulators' substrate. Here, a novel method is demonstrated to design electrically controlled graphene-based modulators that can achieve broadband and spectrally flat modulation of terahertz beams. In our design, a graphene layer is sandwiched between a dielectric and a slightly doped substrate on a metal reflector. It is shown that the spectral dependence of the electric field intensity at the graphene layer can be dramatically modified by optimizing the structural parameters of the device. In this way, the electric field intensity can be spectrally flat and even compensate for the dispersion of the graphene conductivity, resulting in almost invariant absorption in a wide frequency range. Modulation depths up to 76% can be achieved within a fractional operational bandwidth of over 55%. It is expected that our modulator designs will enable the use of terahertz technology in applications requiring broadband operation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

East Asian Monsoon and EL NIÑO-SOUTHERN Oscillation Activities Since the Mid-Holocene Evidences from Massive Corals in the the Central Vietnamese Coast, Western South China Sea

NASA Astrophysics Data System (ADS)

Nguyen, A. D.; Zhao, J.; Feng, Y.; Yu, K.; Gasparon, M.; U-Series Dating Technique Team

2011-12-01

The climate of the Vietnamese coast, western South China Sea (SCS), is driven by the annually reversing East Asian Monsoon (EAM) system which is also related to the El Niño-Southern Oscillation (ENSO) through teleconnection. Our understanding of EAM activity and its connection with global climate is not fully established. In this study high resolution Sr/Ca and δ18O records derived from four fossil Porites sp. corals with U-series ages ranging from ~7000 to 1800 years (yrs) were used to characterise the EAM-ENSO activities since the mid-Holocene. The results show that both the summer and winter monsoons were stronger than present ~ 7000 yrs ago, as evidenced by the higher-than-present amplitudes of annual cycles in SST (9.1 °C) and seawater δ18O (1.4%). The strengthened summer monsoon is considered to result from higher Northern Hemispheric insolation during the mid-Holocene, while the enhanced winter monsoon could be attributed to a reduction/shutdown of North Atlantic Meridional Overturning (NAMOC), leading to a prevailing "cold tongue" off the Vietnamese coast, and an amplified east-west SST gradient in the northern SCS. The EAM was weakened ca. 4200 yrs ago, as reflected by the lower amplitude of SST (4.3 °C) and seawater δ18O (0.57%) annual cycles. The downturn of the EAM is correlated in timing with the cold phase or the Bond event of the high-latitude climate, the Neolithic cultural collapse in China, and the strengthened ENSO in the Pacific. After this downturn, the EAM was slightly strengthened ~3600 and 1800 yrs ago as shown by larger amplitudes of SST (~ 5 °C) and seawater δ18O (1.0-1.2%) annual cycles. The enhanced EAM at these times are out of phase with the high-latitude climate, but are consistent with evidence from historical documents in Vietnam and China. The waxing/waning of the EAM appear to match with the waning/waxing of the ENSO intensity throughout the records since the mid-Holocene. The changes in EAM activity were accompanied by corresponding variations in the annual rainfall pattern, demonstrated by the difference in the timing of the onset and withdrawal of the rainy season. For instance, around 4200 yrs ago, the rainy season started 5.5 months earlier, compared with other times, including the present.

A cost-effective 25-Gb/s EML TOSA using all-in-one FPCB wiring and metal optical bench.

PubMed

Han, Young-Tak; Kwon, Oh-Kee; Lee, Dong-Hun; Lee, Chul-Wook; Leem, Young-Ahn; Shin, Jang-Uk; Park, Sang-Ho; Baek, Yongsoon

2013-11-04

We present a cost-effective 25-Gb/s electro-absorption modulator integrated laser (EML) transmitter optical sub-assembly (TOSA) using all-in-one flexible printed circuit board (FPCB) wiring and a metal optical bench (MOB). For a low cost and high bandwidth TOSA, internal and external wirings and feed-through of the TOSA to transmit radio-frequency (RF) signal are configured all-in-one using the FPCB. The FPCB is extended from an exterior of the TOSA package up to an EML chip inside the package through the slit formed on a rear sidewall of the package and die-bonded on the MOB. The EML TOSA shows a modulated output power of more than 3.5 dBm and a clear eye pattern with a dynamic extinction ratio of ~8.4 dB at a data rate of 25.78 Gb/s.

Photonic integrated circuits based on sampled-grating distributed-Bragg-reflector lasers

NASA Astrophysics Data System (ADS)

Barton, Jonathon S.; Skogen, Erik J.; Masanovic, Milan L.; Raring, James; Sysak, Matt N.; Johansson, Leif; DenBaars, Steven P.; Coldren, Larry A.

2003-07-01

The Sampled-Grating Distributed-Bragg-Reflector laser(SGDBR) provides wide tunability (>40nm), and high output power (>10mW). Driven by the demand for network reconfigurability and ease of implementation, the SGDBR has moved from the research lab to be commercially viable in the marketplace. The SGDBR is most often implemented using an offset-quantum well epitaxial structure in which the quantum wells are etched off in the passive sections. Alternatively, quantum well intermixing has been used recently to achieve the same goal - resulting in improved optical gain and the potential for multiple bandgaps along the device structure. These epitaxial "platforms" provide the basis for more exotic opto-electronic device functionality exhibiting low chirp for digital applications and enhanced linearity for analog applications. This talk will cover state-of-the-art opto-electronic devices based on the SGDBR platform including: integrated Mach-Zehnder modulators, and integrated electro-absorption modulators.

Vector Quantization Algorithm Based on Associative Memories

NASA Astrophysics Data System (ADS)

Guzmán, Enrique; Pogrebnyak, Oleksiy; Yáñez, Cornelio; Manrique, Pablo

This paper presents a vector quantization algorithm for image compression based on extended associative memories. The proposed algorithm is divided in two stages. First, an associative network is generated applying the learning phase of the extended associative memories between a codebook generated by the LBG algorithm and a training set. This associative network is named EAM-codebook and represents a new codebook which is used in the next stage. The EAM-codebook establishes a relation between training set and the LBG codebook. Second, the vector quantization process is performed by means of the recalling stage of EAM using as associative memory the EAM-codebook. This process generates a set of the class indices to which each input vector belongs. With respect to the LBG algorithm, the main advantages offered by the proposed algorithm is high processing speed and low demand of resources (system memory); results of image compression and quality are presented.

Assessing collective affect recognition via the Emotional Aperture Measure.

PubMed

Sanchez-Burks, Jeffrey; Bartel, Caroline A; Rees, Laura; Huy, Quy

2016-01-01

Curiosity about collective affect is undergoing a revival in many fields. This literature, tracing back to Le Bon's seminal work on crowd psychology, has established the veracity of collective affect and demonstrated its influence on a wide range of group dynamics. More recently, an interest in the perception of collective affect has emerged, revealing a need for a methodological approach for assessing collective emotion recognition to complement measures of individual emotion recognition. This article addresses this need by introducing the Emotional Aperture Measure (EAM). Three studies provide evidence that collective affect recognition requires a processing style distinct from individual emotion recognition and establishes the validity and reliability of the EAM. A sample of working managers further shows how the EAM provides unique insights into how individuals interact with collectives. We discuss how the EAM can advance several lines of research on collective affect.

A 10-Gbit/s EML link using detuned narrowband optical filtering.

PubMed

Ebrahimi, P; Jones, R; Wang, Y; Yan, L; Mader, T; Paniccia, M; Willner, A E; Paraschis, L

2007-08-20

In this paper, the effects of asymmetric narrowband optical filtering are investigated in a 10-Gbit/s optical communication link using integrated electro-absorption modulated lasers (EML). We investigate the effect of EML chirp on link performance as well as the optimal filter bandwidth and wavelength detuning. We show that both the phase response and the spectral narrowing of the filter will enable a longer distance transmission by interacting with the EML transient chirp and compensating for the fiber chromatic dispersion. Experimentally, an 8.75-GHz filter is shown to improve the link distance by 40 km from 65 to 105 km, when transmitting over standard single mode fiber.

Vibration Sensor-Based Bearing Fault Diagnosis Using Ellipsoid-ARTMAP and Differential Evolution Algorithms

PubMed Central

Liu, Chang; Wang, Guofeng; Xie, Qinglu; Zhang, Yanchao

2014-01-01

Effective fault classification of rolling element bearings provides an important basis for ensuring safe operation of rotating machinery. In this paper, a novel vibration sensor-based fault diagnosis method using an Ellipsoid-ARTMAP network (EAM) and a differential evolution (DE) algorithm is proposed. The original features are firstly extracted from vibration signals based on wavelet packet decomposition. Then, a minimum-redundancy maximum-relevancy algorithm is introduced to select the most prominent features so as to decrease feature dimensions. Finally, a DE-based EAM (DE-EAM) classifier is constructed to realize the fault diagnosis. The major characteristic of EAM is that the sample distribution of each category is realized by using a hyper-ellipsoid node and smoothing operation algorithm. Therefore, it can depict the decision boundary of disperse samples accurately and effectively avoid over-fitting phenomena. To optimize EAM network parameters, the DE algorithm is presented and two objectives, including both classification accuracy and nodes number, are simultaneously introduced as the fitness functions. Meanwhile, an exponential criterion is proposed to realize final selection of the optimal parameters. To prove the effectiveness of the proposed method, the vibration signals of four types of rolling element bearings under different loads were collected. Moreover, to improve the robustness of the classifier evaluation, a two-fold cross validation scheme is adopted and the order of feature samples is randomly arranged ten times within each fold. The results show that DE-EAM classifier can recognize the fault categories of the rolling element bearings reliably and accurately. PMID:24936949

Impacts of the East Asian Monsoon on springtime dust concentrations over China: IMPACTS OF MONSOON ON DUST

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lou, Sijia; Russell, Lynn M.; Yang, Yang

We use 150 year preindustrial simulations of the Community Earth System Model to quantify the impacts of the East Asian Monsoon strength on interannual variations of springtime dust concentrations over China. The simulated interannual variations in March-April-May (MAM) dust column concentrations range between 20–40% and 10–60% over eastern and western China, respectively. The dust concentrations over eastern China correlate negatively with the East Asian Monsoon (EAM) index, which represents the strength of monsoon, with a regionally averaged correlation coefficient of 0.64. Relative to the strongest EAM years, MAMdust concentrations in the weakest EAM years are higher over China, with regionalmore » relative differences of 55.6%, 29.6%, and 13.9% in the run with emissions calculated interactively and of 33.8%, 10.3%, and 8.2% over eastern, central, and western China, respectively, in the run with prescribed emissions. Both interactive run and prescribed emission run show the similar pattern of climate change between the weakest and strongest EAM years. Strong anomalous northwesterly and westerly winds over the Gobi and Taklamakan deserts during the weakest EAM years result in larger transport fluxes, and thereby increase the dust concentrations over China. These differences in dust concentrations between the weakest and strongest EAM years (weakest-strongest) lead to the change in the net radiative forcing by up to 8 and 3Wm2 at the surface, compared to 2.4 and +1.2Wm2 at the top of the atmosphere over eastern and western China, respectively.« less

Energetics and structural properties of twist grain boundaries in Cu

NASA Technical Reports Server (NTRS)

Karimi, Majid

1992-01-01

Structural and energetics properties of atoms near a grain boundary are of great importance from theoretical and experimental standpoints. From various experimental work it is concluded that diffusion at low temperatures at polycrystalline materials take place near grain boundary. Experimental and theoretical results also indicate changes of up to 70 percent in physical properties near a grain boundary. The Embedded Atom Method (EAM) calculations on structural properties of Au twist grain boundaries are in quite good agreement with their experimental counterparts. The EAM is believed to predict reliable values for the single vacancy formation energy as well as migration energy. However, it is not clear whether the EAM functions which are fitted to the bulk properties of a perfect crystalline solid can produce reliable results on grain boundaries. One of the objectives of this work is to construct the EAM functions for Cu and use them in conjunction with the molecular static simulation to study structures and energetics of atoms near twist grain boundaries in Cu. This provides tests of the EAM functions near a grain boundary. In particular, we determine structure, single vacancy formation energy, migration energy, single vacancy activation energy, and interlayer spacing as a function of distance from grain boundary. Our results are compared with the available experimental and theoretical results from grain boundaries and bulk.

Social cognition in a case of amnesia with neurodevelopmental mechanisms.

PubMed

Staniloiu, Angelica; Borsutzky, Sabine; Woermann, Friedrich G; Markowitsch, Hans J

2013-01-01

Episodic-autobiographical memory (EAM) is considered to emerge gradually in concert with the development of other cognitive abilities (such as executive functions, personal semantic knowledge, emotional knowledge, theory of mind (ToM) functions, language, and working memory). On the brain level its emergence is accompanied by structural and functional reorganization of different components of the so-called EAM network. This network includes the hippocampal formation, which is viewed as being vital for the acquisition of memories of personal events for long-term storage. Developmental studies have emphasized socio-cultural-linguistic mechanisms that may be unique to the development of EAM. Furthermore it was hypothesized that one of the main functions of EAM is the social one. In the research field, the link between EAM and social cognition remains however debated. Herein we aim to bring new insights into the relation between EAM and social information processing (including social cognition) by describing a young adult patient with amnesia with neurodevelopmental mechanisms due to perinatal complications accompanied by hypoxia. The patient was investigated medically, psychiatrically, and with neuropsychological and neuroimaging methods. Structural high resolution magnetic resonance imaging revealed significant bilateral hippocampal atrophy as well as indices for degeneration in the amygdalae, basal ganglia, and thalamus, when a less conservative threshold was applied. In addition to extensive memory investigations and testing other (non-social) cognitive functions, we employed a broad range of tests that assessed social information processing (social perception, social cognition, social regulation). Our results point to both preserved (empathy, core ToM functions, visual affect selection, and discrimination, affective prosody discrimination) and impaired domains of social information processing (incongruent affective prosody processing, complex social judgments). They support proposals for a role of the hippocampal formation in processing more complex social information that likely requires multimodal relational handling.

Social cognition in a case of amnesia with neurodevelopmental mechanisms

PubMed Central

Staniloiu, Angelica; Borsutzky, Sabine; Woermann, Friedrich G.; Markowitsch, Hans J.

2013-01-01

Episodic–autobiographical memory (EAM) is considered to emerge gradually in concert with the development of other cognitive abilities (such as executive functions, personal semantic knowledge, emotional knowledge, theory of mind (ToM) functions, language, and working memory). On the brain level its emergence is accompanied by structural and functional reorganization of different components of the so-called EAM network. This network includes the hippocampal formation, which is viewed as being vital for the acquisition of memories of personal events for long-term storage. Developmental studies have emphasized socio-cultural-linguistic mechanisms that may be unique to the development of EAM. Furthermore it was hypothesized that one of the main functions of EAM is the social one. In the research field, the link between EAM and social cognition remains however debated. Herein we aim to bring new insights into the relation between EAM and social information processing (including social cognition) by describing a young adult patient with amnesia with neurodevelopmental mechanisms due to perinatal complications accompanied by hypoxia. The patient was investigated medically, psychiatrically, and with neuropsychological and neuroimaging methods. Structural high resolution magnetic resonance imaging revealed significant bilateral hippocampal atrophy as well as indices for degeneration in the amygdalae, basal ganglia, and thalamus, when a less conservative threshold was applied. In addition to extensive memory investigations and testing other (non-social) cognitive functions, we employed a broad range of tests that assessed social information processing (social perception, social cognition, social regulation). Our results point to both preserved (empathy, core ToM functions, visual affect selection, and discrimination, affective prosody discrimination) and impaired domains of social information processing (incongruent affective prosody processing, complex social judgments). They support proposals for a role of the hippocampal formation in processing more complex social information that likely requires multimodal relational handling. PMID:23805111

Nonlinearity-aware 200  Gbit/s DMT transmission for C-band short-reach optical interconnects with a single packaged electro-absorption modulated laser.

PubMed

Zhang, Lu; Hong, Xuezhi; Pang, Xiaodan; Ozolins, Oskars; Udalcovs, Aleksejs; Schatz, Richard; Guo, Changjian; Zhang, Junwei; Nordwall, Fredrik; Engenhardt, Klaus M; Westergren, Urban; Popov, Sergei; Jacobsen, Gunnar; Xiao, Shilin; Hu, Weisheng; Chen, Jiajia

2018-01-15

We experimentally demonstrate the transmission of a 200 Gbit/s discrete multitone (DMT) at the soft forward error correction limit in an intensity-modulation direct-detection system with a single C-band packaged distributed feedback laser and traveling-wave electro absorption modulator (DFB-TWEAM), digital-to-analog converter and photodiode. The bit-power loaded DMT signal is transmitted over 1.6 km standard single-mode fiber with a net rate of 166.7 Gbit/s, achieving an effective electrical spectrum efficiency of 4.93 bit/s/Hz. Meanwhile, net rates of 174.2 Gbit/s and 179.5 Gbit/s are also demonstrated over 0.8 km SSMF and in an optical back-to-back case, respectively. The feature of the packaged DFB-TWEAM is presented. The nonlinearity-aware digital signal processing algorithm for channel equalization is mathematically described, which improves the signal-to-noise ratio up to 3.5 dB.

Quadratic electroabsorption studies of molecular motion in dye-doped polymers

NASA Astrophysics Data System (ADS)

Poga, Constantina; Kuzyk, Mark G.; Dirk, Carl W.

1993-02-01

This paper reports on quadratic electroabsorption studies of thin-film solid solutions of squarylium dye molecules in poly(methylmethacrylate) polymer with the aim of understanding the role of electronic and reorientational mechanisms in the third-order nonlinear-optical susceptibility. We present a generalized theory of the quadratic electrooptic response that includes both electronic mechanisms and molecular reorientation and show that the ratio of two independent third-order susceptibility tensor components, namely (chi) (3)3333/(chi) (3)1133, determines the relative contribution of each mechanism. Based on these theoretical results, we have designed and built an experiment that determines this ratio as a function of temperature and wavelength. Results show that at room temperature and near the first electronic transition wavelength, the response is dominated by the electronic mechanism, and that the reorientational contribution dominates when the sample is heated above its glass transition temperature. Furthermore, results show that, off-resonance, the sign of the imaginary part of the third-order susceptibility is positive. Quadratic electroabsorption is thus shown to be a versatile tool for measuring the imaginary part of the third-order nonlinear-optical susceptibility which yields information about the interaction of polymer and dopant molecule.

Characterization of the excited states of a squaraine molecule with quadratic electroabsorption spectroscopy

NASA Astrophysics Data System (ADS)

Poga, C.; Brown, T. M.; Kuzyk, M. G.; Dirk, Carl W.

1995-04-01

We apply quadratic electroabsorption spectroscopy (QES) to thin-film solid solutions of squarylium dye molecules in poly(methyl methacrylate) polymer to study the dye's electronic excited states and to investigate the importance of these states with regard to their contribution to the third-order nonlinear-optical susceptibility. We first show that the room-temperature tensor ratio a= chi (3)3333/ chi (3)1133 \\approximately 3 throughout most of the visible region to establish that the electronic mechanism dominates. Because QES is a third-order nonlinear-optical susceptibility measurement, it can be used to identify two photon states. By obtaining good agreement between the quadratic electroabsorption spectrum and a three level model, we conclude that there are two dominant states that contribute to the near-resonant and a two-photon state that are separated by less than 0.2 eV in energy. QES is thus shown to be a versatile tool for measuring the nature of excited states in a molecule. Furthermore, by applying a Kramers-Kronig transformation to determine the real part of the response, we are able to assess the two-photon all-optical device figure of merit of these materials. Such an

Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study.

PubMed

Crivillers, N; Liscio, A; Di Stasio, F; Van Dyck, C; Osella, S; Cornil, D; Mian, S; Lazzerini, G M; Fenwick, O; Orgiu, E; Reinders, F; Braun, S; Fahlman, M; Mayor, M; Cornil, J; Palermo, V; Cacialli, F; Samorì, P

2011-08-28

Responsive monolayers are key building blocks for future applications in organic and molecular electronics in particular because they hold potential for tuning the physico-chemical properties of interfaces, including their energetics. Here we study a photochromic SAM based on a conjugated azobenzene derivative and its influence on the gold work function (Φ(Au)) when chemisorbed on its surface. In particular we show that the Φ(Au) can be modulated with external stimuli by controlling the azobenzene trans/cis isomerization process. This phenomenon is characterized experimentally by four different techniques, kelvin probe, kelvin probe force microscopy, electroabsorption spectroscopy and ultraviolet photoelectron spectroscopy. The use of different techniques implies exposing the SAM to different measurement conditions and different preparation methods, which, remarkably, do not alter the observed work function change (Φ(trans)-Φ(cis)). Theoretical calculations provided a complementary insight crucial to attain a deeper knowledge on the origin of the work function photo-modulation.

Gigahertz speed operation of epsilon-near-zero silicon photonic modulators

DOE PAGES

Wood, Michael G.; Campione, Salvatore; Parameswaran, S.; ...

2018-02-21

Opmore » tical communication systems increasingly require electro-optical modulators that deliver high modulation speeds across a large optical bandwidth with a small device footprint and a CMOS-compatible fabrication process. Although silicon photonic modulators based on transparent conducting oxides (TCOs) have shown promise for delivering on these requirements, modulation speeds to date have been limited. Here, we describe the design, fabrication, and performance of a fast, compact electroabsorption modulator based on TCOs. The modulator works by using bias voltage to increase the carrier density in the conducting oxide, which changes the permittivity and hence optical attenuation by almost 10 dB. Under bias, light is tightly confined to the conducting oxide layer through nonresonant epsilon-near-zero (ENZ) effects, which enable modulation over a broad range of wavelengths in the telecommunications band. Our approach features simple integration with passive silicon waveguides, the use of stable inorganic materials, and the ability to modulate both transverse electric and magnetic polarizations with the same device design. Using a 4-μm-long modulator and a drive voltage of 2 V p p , we demonstrate digital modulation at rates of 2.5 Gb/s. We report broadband operation with a 6.5 dB extinction ratio across the 1530–1590 nm band and a 10 dB insertion loss. This work verifies that high-speed ENZ devices can be created using conducting oxide materials and paves the way for additional technology development that could have a broad impact on future optical communications systems.« less

Gigahertz speed operation of epsilon-near-zero silicon photonic modulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, Michael G.; Campione, Salvatore; Parameswaran, S.

Opmore » tical communication systems increasingly require electro-optical modulators that deliver high modulation speeds across a large optical bandwidth with a small device footprint and a CMOS-compatible fabrication process. Although silicon photonic modulators based on transparent conducting oxides (TCOs) have shown promise for delivering on these requirements, modulation speeds to date have been limited. Here, we describe the design, fabrication, and performance of a fast, compact electroabsorption modulator based on TCOs. The modulator works by using bias voltage to increase the carrier density in the conducting oxide, which changes the permittivity and hence optical attenuation by almost 10 dB. Under bias, light is tightly confined to the conducting oxide layer through nonresonant epsilon-near-zero (ENZ) effects, which enable modulation over a broad range of wavelengths in the telecommunications band. Our approach features simple integration with passive silicon waveguides, the use of stable inorganic materials, and the ability to modulate both transverse electric and magnetic polarizations with the same device design. Using a 4-μm-long modulator and a drive voltage of 2 V p p , we demonstrate digital modulation at rates of 2.5 Gb/s. We report broadband operation with a 6.5 dB extinction ratio across the 1530–1590 nm band and a 10 dB insertion loss. This work verifies that high-speed ENZ devices can be created using conducting oxide materials and paves the way for additional technology development that could have a broad impact on future optical communications systems.« less

Research on High-Bandgap Materials and Amorphous Silicon-Based Solar Cells, Final Technical Report, 15 May 1994-15 January 1998

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiff, E. A.; Gu, Q.; Jiang, L.

1998-12-28

This report describes work performed by Syracuse University under this subcontract. Researchers developed a technique based on electroabsorption measurements for obtaining quantitative estimates of the built-in potential Vbi in a-Si:H-based heterostructure solar cells incorporating microcrystalline or a-SiC:H p layers. Using this new electroabsorption technique, researchers confirmed previous estimates of Vbi {yields} 1.0 V in a-Si:H solar cells with ''conventional'' intrinsic layers and either microcrystalline or a-SiC:H p layers. Researchers also explored the recent claim that light-soaking of a-Si:H substantially changes the polarized electroabsorption associated with interband optical transitions (and hence, not defect transitions). Researchers confirmed measurements of improved (5') holemore » drift mobilities in some specially prepared a-Si:H samples. Disturbingly, solar cells made with such materials did not show improved efficiencies. Researchers significantly clarified the relationship of ambipolar diffusion-length measurements to hole drift mobilities in a-Si:H, and have shown that the photocapacitance measurements can be interpreted in terms of hole drift mobilities in amorphous silicon. They also completed a survey of thin BP:H and BPC:H films prepared by plasma deposition using phosphine, diborane, trimethylboron, and hydrogen as precursor gases.« less

Comparative absorption, electroabsorption and electrochemical studies of intervalence electron transfer and electronic coupling in cyanide-bridged bimetallic systems: ancillary ligand effects

NASA Astrophysics Data System (ADS)

Vance, Fredrick W.; Slone, Robert V.; Stern, Charlotte L.; Hupp, Joseph T.

2000-03-01

Electroabsorption or Stark spectroscopy has been used to evaluate the systems (NC) 5M II-CN-Ru III(NH 3) 51- and (NC) 5M II-CN-Ru III(NH 3) 4py 1-, where M II=Fe II or Ru II. When a pyridine ligand is present in the axial position on the Ru III acceptor, the effective optical electron transfer distance - as measured by the change in dipole moment, |Δ μ| - is increased by more than 35% relative to the ammine substituted counterpart. Comparison of the charge transfer distances to the crystal structure of Na[(CN) 5Fe-CN-Ru(NH 3) 4py] · 6H 2O reveals that the Stark derived distances are ˜50% to ˜90% of the geometric separation of the metal centers. The differences result in an upward revision in the Hush delocalization parameter, c b2, and of the electronic coupling matrix element, H ab, relative to those parameters obtained exclusively from electronic absorption measurements. The revised parameters are compared to those, which are obtained via electrochemical techniques and found to be in only fair agreement. We conclude that the absorption/electroabsorption analysis likely yields a more reliable set of mixing and coupling parameters.

Absorption and electroabsorption spectra of carotenoid cation radical and dication

NASA Astrophysics Data System (ADS)

Krawczyk, Stanisław

1998-05-01

Radical cations and dications of two carotenoids astaxanthin and canthaxanthin were prepared by oxidation with FeCl 3 in fluorinated alcohols at room temperature. Absorption and electroabsorption (Stark effect) spectra were recorded for astaxanthin cations in mixed frozen matrices at temperatures about 160 K. The D 0→D 2 transition in cation radical is at 835 nm. The electroabsorption spectrum for the D 0→D 2 transition exhibits a negative change of molecular polarizability, Δ α=-1.2·10 -38 C·m 2/V (-105 A 3), which seems to originate from the change in bond order alternation in the ground state rather than from the electric field-induced interaction of D 1 and D 2 excited states. Absorption spectrum of astaxanthin dication is located at 715-717 nm, between those of D 0→D 2 in cation radical and S 0→S 2 in neutral carotenoid. Its shape reflects a short vibronic progression and strong inhomogeneous broadening. The polarizability change on electronic excitation, Δ α=2.89·10 -38 C·m 2/V (260 A 3), is five times smaller than in neutral astaxanthin. This value reflects the larger energetic distance from the lowest excited state to the higher excited states than in the neutral molecule.

Optical NAND gate

DOEpatents

Skogen, Erik J [Albuquerque, NM; Raring, James [Goleta, CA; Tauke-Pedretti, Anna [Albuquerque, NM

2011-08-09

An optical NAND gate is formed from two pair of optical waveguide devices on a substrate, with each pair of the optical waveguide devices consisting of an electroabsorption modulator and a photodetector. One pair of the optical waveguide devices is electrically connected in parallel to operate as an optical AND gate; and the other pair of the optical waveguide devices is connected in series to operate as an optical NOT gate (i.e. an optical inverter). The optical NAND gate utilizes two digital optical inputs and a continuous light input to provide a NAND function output. The optical NAND gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Computer-Aided Design and Computer-Aided Manufacturing Hydroxyapatite/Epoxide Acrylate Maleic Compound Construction for Craniomaxillofacial Bone Defects.

PubMed

Zhang, Lei; Shen, Shunyao; Yu, Hongbo; Shen, Steve Guofang; Wang, Xudong

2015-07-01

The aim of this study was to investigate the use of computer-aided design and computer-aided manufacturing hydroxyapatite (HA)/epoxide acrylate maleic (EAM) compound construction artificial implants for craniomaxillofacial bone defects. Computed tomography, computer-aided design/computer-aided manufacturing and three-dimensional reconstruction, as well as rapid prototyping were performed in 12 patients between 2008 and 2013. The customized HA/EAM compound artificial implants were manufactured through selective laser sintering using a rapid prototyping machine into the exact geometric shapes of the defect. The HA/EAM compound artificial implants were then implanted during surgical reconstruction. Color-coded superimpositions demonstrated the discrepancy between the virtual plan and achieved results using Geomagic Studio. As a result, the HA/EAM compound artificial bone implants were perfectly matched with the facial areas that needed reconstruction. The postoperative aesthetic and functional results were satisfactory. The color-coded superimpositions demonstrated good consistency between the virtual plan and achieved results. The three-dimensional maximum deviation is 2.12 ± 0.65  mm and the three-dimensional mean deviation is 0.27 ± 0.07  mm. No facial nerve weakness or pain was observed at the follow-up examinations. Only 1 implant had to be removed 2 months after the surgery owing to severe local infection. No other complication was noted during the follow-up period. In conclusion, computer-aided, individually fabricated HA/EAM compound construction artificial implant was a good craniomaxillofacial surgical technique that yielded improved aesthetic results and functional recovery after reconstruction.

The Evolution of Tropospheric Temperature Field and its Relationship With The Onset of Asian Summer Monsoon

NASA Technical Reports Server (NTRS)

He, H.; Sui, C-H.; Jian, M.; Wen, Z.

2000-01-01

The mean state and year-to-year variations of the tropospheric temperature fields and their relationship with the establishment of the summertime East Asian monsoon (EAM) and the Indian monsoon (INM) are studied using the NCEP reanalysis data of 15 years (1982-1996). The results show that the seasonal shift of the South Asian High in the upper troposphere and the establishment of the EAM and the INM are closely related to the seasonal warming which causes a reversal of the meridional gradient of upper tropospheric mean temperature over the monsoon regions. On the average of 15 years, the reversal time of the temperature gradient in the EAM region (INM region) is concurrent with (one pentad earlier than) the onset time of the summer monsoon. In most years of the 15-year period, the reversal of temperature gradient coincides or precedes the onset time of the summer monsoon in both the EAM region and the INM region. The results suggest an important role of thermal processes on the establishment of the Asian monsoon. The contributors to the upper tropospheric warming over the EAM region are the strong horizontal warm advection and the diabetic heating against the adiabatic cooling due to upward motion. In the INM region, strong adiabatic heating by subsidence and the diabetic heating are major warming processes against the strong horizontal cold advection related to the persistent northwestlies to the southwestern periphery of the Tibetan Plateau. It appears that the early or late establishment of the Asian summer monsoon is not directly related to the differential warming near the surface.

The study of attenuation levels and the comfort of earplugs.

PubMed

Samelli, Alessandra G; Gomes, Raquel F; Chammas, Tiago V; Silva, Bárbara G; Moreira, Renata R; Fiorini, Ana C

2018-01-01

This study aimed to analyze and compare four different types of earplugs, divided into premolded plugs and foam plug models, in relation to the level of attenuation, comfort, and the size of the external acoustic meatus (EAM) in an attempt to identify how these variables influence the choice of specific hearing protection devices (HPDs). A cross-sectional observational study was performed in a sample of 49 participants, oriented toward the ideal placement of four HPDs, two premolded and two foam plugs (3M™). The procedures included otoscopy, EAM diameter measurement using an otometer, EAM volume measurement via an acoustic impedance test, and the obtainment of the bilateral personal attenuation rating (PAR) for each HPD using the E-A-Rfit™ Validation System (3M™). The Bipolar Comfort Rating Scale (BCRS) instrument was applied twice for each individual: once after the evaluations with the premolded HPDs and again after the evaluations with the foam plug HPDs. Then, each participant was asked which was his/her favorite protector. The volume of the EAM was not directly related to the diameter of the EAM. The attenuation did not interfere with the HPD preference, and the PAR of the foam plug was significantly higher regardless of the preferred HPD. Regarding the BCRS, the variables "Placement," "Complexity," and "Occlusion Effect" had higher scores for premolded HPDs and had a direct relationship with the type of preferred HPD. Attention to the use of HPDs should be personalized, taking into account the needs of each individual, considering not only the attenuation, but also the user's reported well-being.

Late Holocene monsoon climate of northeastern Taiwan inferred from elemental (C, N) and isotopic (δ13C, δ15N) data in lake sediments

NASA Astrophysics Data System (ADS)

Selvaraj, Kandasamy; Wei, Kuo-Yen; Liu, Kon-Kee; Kao, Shuh-Ji

2012-03-01

Little information exists about centennial-scale climate variability on oceanic islands in the western Pacific where the East Asian monsoon (EAM) strongly influences the climate, mountain ecosystem and the society. In this study, we investigate a 168 cm long sediment core recovered from Emerald Peak Lake in subalpine NE Taiwan for the contents of grain size, total organic carbon (TOC), C/N ratio, and stable isotopes (δ13C and δ15N) to reconstruct the monsoon climate and vegetation density during the late Holocene. Six radiocarbon (14C) ages obtained on plant remains used for the chronology indicate that the sediment core has been accumulated since ˜3770 cal BP with a mean sedimentation rate of 44.6 cm/ka. The sub-centennial resolution of our proxy records reveals strong fluctuations of the EAM and vegetation density for the past ˜3770 cal BP. The greater contents of coarse and medium sediments with overall decreasing trends from 3770 to 2000 cal BP suggest an increasing fine sediment influx from the catchment likely due to an increasing lake water level. Although low TOC content, C/N ratio, and enriched δ13C values in bulk and fine sediments during this interval suggest a sparsely vegetated catchment, increasing trends of TOC content and C/N ratio together with decreasing trends of δ13C and δ15N values indicate a strengthening pattern of summer monsoon. This is in contrast to a decreasing monsoon strength inferred from Dongge Cave δ18O record at that time, supporting the idea of anti-phasing of summer EAM and Indian summer monsoon. Since 2000 cal BP, higher content of fine sediments with high TOC content and C/N ratio but relatively depleted δ13C and low δ15N values suggest a high but stable lake water level and dense C3 plants, consistent with a stronger summer monsoon in a wet climate. Within this general trend, we interpret a prominent change of proxy parameters in sediments from ˜560 to 150 cal BP, as subtropical evidence for the Little Ice Age in NE Taiwan. By comparing our proxy records with other diverse land and marine records from southern China and adjoining marine realm, we demonstrate that the centennial to millennial-scale fluctuations of the summer EAM over the northeastern Taiwan during the late Holocene have been largely modulated by the tropical Pacific forcing through El Niño along with solar forcing.

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren

PubMed Central

Chen, Junhong; He, Ji C.; Chen, Yunyun; Xu, Jingjing; Wu, Haoran; Wang, Feifu; Lu, Fan; Jiang, Jun

2016-01-01

Purpose Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren. Methods Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master. Results The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group. Conclusion Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia. PMID:26881745

Interocular Difference of Peripheral Refraction in Anisomyopic Eyes of Schoolchildren.

PubMed

Chen, Junhong; He, Ji C; Chen, Yunyun; Xu, Jingjing; Wu, Haoran; Wang, Feifu; Lu, Fan; Jiang, Jun

2016-01-01

Refraction in the peripheral visual field is believed to play an important role in the development of myopia. The purpose of this study was to investigate the differences in peripheral refraction among anisomyopia, isomyopia, and isoemmetropia for schoolchildren. Thirty-eight anisomyopic children were recruited and divided into two groups: (1) both eyes were myopic (anisomyopic group, AM group) and (2) one eye was myopic and the contralateral eye was emmetropic (emmetropic anisomyopic group, EAM group). As controls, 45 isomyopic and isoemmetropic children were also recruited with age and central spherical equivalent (SE) matched to those of the AM and EAM groups. The controls were divided into three groups: (1) intermediate myopia group (SE matched to the more myopic eye of AM group), (2) low myopia group (SE matched to the less myopic eye of AM group and the more myopic eye of EAM group), and (3) emmetropia group (SE matched to the less myopic eye of EAM group). Peripheral refraction at 7 points across the central ±30° on the horizontal visual field with a 10° interval was measured with an autorefractor. Axial length (AL), corneal curvature (CC), and anterior chamber depth (ACD) were also determined by using the Zeiss IOL-Master. The relative peripheral spherical equivalent [RPR(M)] and relative peripheral spherical value [RPR(S)] of the more myopic eye was shifted more hyperopically than the contralateral eye in both the AM and the EAM groups (both p<0.0001). The RPR(M, S) of the less myopic eyes in the AM and EAM groups showed a relatively flat trend across the visual field and were not significantly different from the emmetropia group. The RPR(M, S) of less myopic eyes in the AM group were shifted less hyperopically than in the isomyopic low myopia group and the more myopic eye of the EAM group [RPR(M), p = 0.007; RPR(S), p = 0.001], although the central SEs of the three groups were not significantly different from each other. However, RPR(M, S) of the more myopic eyes were not different from the corresponding isomyopic groups. There was also no significant difference in the relative peripheral astigmatism [RPR(J0, J45)] between the more and the less myopic eyes in either the AM or the EAM group. Refraction of anisomyopia differs between the two eyes not only at the central visual field but also at the off-axis periphery. The relative peripheral refraction of the more myopic eye of anisomyopia was shifted hyperopically, as occurs in isomyopia with similar central subjective SE values. Less myopic eyes were much less hyperopically shifted in relative peripheral refraction than the corresponding isomyopic eyes, but are comparable to emmetropic eyes. This emmetropia-like relative peripheral refraction in less myopic eyes might be a factor responsible for slowing down the progression of myopia.

Advanced Monitoring of Migratory Birds on Military Lands

DTIC Science & Technology

2010-03-01

BRSP Brewer‟s Sparrow BTSP Black - throated Sparrow BLGR Blue Grosbeak CAKI Cassin‟s Kingbird CONI Common Nighthawk EAME Eastern...Fuller et al. 1998). This approach has been used for many species, ranging from Black - throated Sparrow (Amphispiza bilineata, Pidgeon et al 2003) to...lightest yellow indicates a predicted abundance of zero. Species acronym key: BTSP Black - throated Sparrow ; EAME Eastern Meadowlark; WEKI Western

Differences in Arachidonic Acid Levels and Fatty Acid Desaturase (FADS) Gene Variants in African Americans and European Americans with Diabetes/Metabolic Syndrome

PubMed Central

Sergeant, Susan; Hugenschmidt, Christina E.; Rudock, Megan E.; Ziegler, Julie T.; Ivester, Priscilla; Ainsworth, Hannah C.; Vaidya, Dhananjay; Case, L. Douglas; Langefeld, Carl D.; Freedman, Barry I.; Bowden, Donald W.; Mathias, Rasika A.; Chilton, Floyd H.

2012-01-01

Over the past 50 years, increases in dietary n-6 polyunsaturated fatty acids (PUFAs), such as linoleic acid, have been hypothesized to cause or exacerbate chronic inflammatory diseases. This study examines an individual’s innate capacity to synthesize n-6-long chain PUFAs (LC-PUFAs), with respect to the fatty acid desaturase (FADS) locus in Americans of African and European descent with diabetes/metabolic syndrome. Compared to European Americans (EAm), African Americans (AfAm) exhibited markedly higher serum levels of arachidonic acid (AA) (EAm 7.9±2.1; AfAm 9.8±1.9 % of total fatty acids, mean ± sd; p<2.29×10−9) and the AA to n-6-precursor fatty acid ratio, which estimates FADS1 activity (EAm 5.4±2.2, AfAm 6.9±2.2; p=1.44×10−5). Seven single nucleotide polymorphisms (SNP) mapping to the FADS locus revealed strong association with AA, eicosapentaenoic acid (EPA) and dihomogamma-linolenic acid (DGLA) in the EAm. Importantly, EAm homozygous for the minor allele (T) had significantly lower AA levels (TT: 6.3±1.0; GG: 8.5±2.1; p=3.0×10−5) and AA/DGLA ratios (TT: 3.4±0.8; GG: 6.5±2.3; p=2.2×10−7) but higher DGLA levels (TT: 1.9±0.4; GG: 1.4±0.4; p=3.3×10−7) compared to those homozygous for the major allele (GG). Allele frequency patterns suggest that the GG genotype at rs174537 (associated with higher circulating levels of AA) is much higher in AfAm (0.81) compared to EAm (0.46). Similarly, marked differences in rs174537 genotypic frequencies were observed in HapMap populations. These data suggest that there are likely important differences in the capacity of different populations to synthesize LC-PUFAs. These differences may provide a genetic mechanism contributing to health disparities between populations of African and European descent. PMID:21733300

Effects of 1, 25-Dihydroxyvitamin D3 on Experimental Autoimmune Myocarditis in Mice.

PubMed

Hu, Fen; Yan, Lianhua; Lu, Shuai; Ma, Wenhan; Wang, Ya; Wei, Yuzhen; Yan, Xiaofei; Zhao, Xin; Chen, Zhijian; Wang, Zhaohui; Cheng, Bo

2016-01-01

Myocarditis is an important inflammatory disease of the heart which causes life-threatening conditions. 1, 25(OH)2 D3 has effects on multiple systems and diseases. The present study was aimed to investigate the effect of 1, 25(OH)2 D3 on experimental autoimmune myocarditis (EAM), and explored the underlying mechanisms involved. EAM was induced by immunizing BALB/c mice with cardiac α-myosin heavy chain peptides (MyHC-α). 1, 25(OH)2 D3 (1,000 ng/kg once) or vehicle was administered intraperitoneally every other day during the entire experiment. On day 21, transthoracic echocardiography was performed and cardiac inflammatory infiltration was detected by hematoxylin and eosin (HE). The terminal deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL) assay, and Western blots for the expression of protein caspase-3 and cleaved-caspase3 were used to evaluate apoptosis. Transmission electron microscopy and Western blots for the expression of protein Beclin-1, LC3B, and P62 were used to evaluate autophagy. The ratio of heart weight/body weight was significantly reduced in 1, 25(OH)2 D3 -treated EAM mice, compared with vehicle -treated ones. 1, 25(OH)2 D3 treatment improved cardiac function, diminished cell infiltration in cardiac, suppressed myocardial apoptosis, decreased the number of autophagosomes, and decreased the protein expression of Beclin-1, LC3-II and p62. The present results demonstrated that administration of 1, 25(OH)2 D3 decreased EAM severity. 1, 25(OH)2 D3 treatment may be a feasible therapeutic approach for EAM. © 2016 The Author(s) Published by S. Karger AG, Basel.

The effect of day-neutral mutations in barley and wheat on the interaction between photoperiod and vernalization.

PubMed

Turner, Adrian S; Faure, Sébastien; Zhang, Yang; Laurie, David A

2013-09-01

Vernalization-2 (Vrn-2) is the major flowering repressor in temperate cereals. It is only expressed under long days in wild-type plants. We used two day-neutral (photoperiod insensitive) mutations that allow rapid flowering in short or long days to investigate the day length control of Vrn-2. The barley (Hordeum vulgare) early maturity8 (eam8) mutation affects the barley ELF3 gene. eam8 mutants disrupt the circadian clock resulting in elevated expression of Ppd-H1 and the floral activator HvFT1 under short or long days. When eam8 was crossed into a genetic background with a vernalization requirement Vrn-2 was expressed under all photoperiods and the early flowering phenotype was partially repressed in unvernalized (UV) plants, likely due to competition between the constitutively active photoperiod pathway and the repressing effect of Vrn-2. We also investigated the wheat (Triticum aestivum) Ppd-D1a mutation. This differs from eam8 in causing elevated levels of Ppd-1 and TaFT1 expression without affecting the circadian clock. We used genotypes that differed in "short-day vernalization". Short days were effective in promoting flowering in individuals wild type at Ppd-D1, but not in individuals that carry the Ppd-D1a mutation. The latter showed Vrn-2 expression in short days. In summary, eam8 and Ppd-D1a mimic long days in terms of photoperiod response, causing Vrn-2 to become aberrantly expressed (in short days). As Ppd-D1a does not affect the circadian clock, this also shows that clock regulation of Vrn-2 operates indirectly through one or more downstream genes, one of which may be Ppd-1.

Linking Monsoon Activity with River-Derived Sediment Deposition in the northern South China Sea

NASA Astrophysics Data System (ADS)

Ge, Q.; Xue, Z. G.; Liu, P.; Chu, F.

2016-02-01

Sediments retrieved from a gravity core were analyzed to examine the connection between East Asian Monsoon (EAM) and river-derived sediment deposition on the continental slope in the South China Sea since the Last Glacial Maximum. Combined clay mineralogy and grain size index analysis provided evidence of the sources of fine-grained sediment as well as for rebuilding the history of paleo-EAM. A shift of sediment source from the Pearl River to southwestern Taiwanese rivers was identified during the Holocene. The 4-8μm grain size fraction, as an environmental sensitive component and thus the EAM proxy, indicated the local deposition environment is mainly controlled by sea-level variations. And during the Holocene, the East Asian summer monsoon exhibited an in-phase relationship with East Asian winter monsoon, both following variations of the insolation intensity.

Embedded atom method potential for studying mechanical properties of binary Cu–Au alloys

NASA Astrophysics Data System (ADS)

Gola, Adrien; Pastewka, Lars

2018-07-01

We present an embedded atom method (EAM) potential for the binary Cu–Au system. The unary phases are described by two well-tested unary EAM potentials for Cu and Au. We fitted the interaction between Cu and Au to experimental properties of the binary intermetallic phases Cu3Au, CuAu and CuAu3. Particular attention has been paid to reproducing stacking fault energies in order to obtain a potential suitable for studying deformation in this binary system. The resulting energies, lattice constant, elastic properties and melting points are in good agreement with available experimental data. We use nested sampling to show that our potential reproduces the phase boundaries between intermetallic phases and the disordered face-centered cubic solid solution. We benchmark our potential against four popular Cu–Au EAM parameterizations and density-functional theory calculations.

Forest health monitoring in the Ngangao Forest, Taita Tills, Kenya: A five year assessment of change

Treesearch

Paul C. Rogers; Barbara O' Connell; James Mwang' ombe; Seif Madoffe; Gerard Hertel

2008-01-01

Forest Health Monitoring (FHM) provides a standardized detection-level survey of forest and tree characteristics for large forested areas. We have adopted FHM methods from this temperate-based program to tropical forests in the Eastern Arc Mountains (EAM) of Kenya and Tanzania. This paper reports the first assessment of trend data in the EAM over a period from 2001 to...

Change of ocean circulation in the East Asian Marginal Seas under different climate conditions

NASA Astrophysics Data System (ADS)

Min, Hong Sik; Kim, Cheol-Ho; Kim, Young Ho

2010-05-01

Global climate models do not properly resolve an ocean environment in the East Asian Marginal Seas (EAMS), which is mainly due to a poor representation of the topography in continental shelf region and a coarse spatial resolution. To examine a possible change of ocean environment under global warming in the EAMS, therefore we used North Pacific Regional Ocean Model. The regional model was forced by atmospheric conditions extracted from the simulation results of the global climate models for the 21st century projected by the IPCC SRES A1B scenario as well as the 20th century. The North Pacific Regional Ocean model simulated a detailed pattern of temperature change in the EAMS showing locally different rising or falling trend under the future climate condition, while the global climate models simulated a simple pattern like an overall increase. Changes of circulation pattern in the EAMS such as an intrusion of warm water into the Yellow Sea as well as the Kuroshio were also well resolved. Annual variations in volume transports through the Taiwan Strait and the Korea Strait under the future condition were simulated to be different from those under present condition. Relative ratio of volume transport through the Soya Strait to the Tsugaru Strait also responded to the climate condition.

HvLUX1 is a candidate gene underlying the early maturity 10 locus in barley: phylogeny, diversity, and interactions with the circadian clock and photoperiodic pathways

PubMed Central

Campoli, Chiara; Pankin, Artem; Drosse, Benedikt; Casao, Cristina M; Davis, Seth J; von Korff, Maria

2013-01-01

Photoperiodic flowering is a major factor determining crop performance and is controlled by interactions between environmental signals and the circadian clock. We proposed Hvlux1, an ortholog of the Arabidopsis circadian gene LUX ARRHYTHMO, as a candidate underlying the early maturity 10 (eam10) locus in barley (Hordeum vulgare L.). The link between eam10 and Hvlux1 was discovered using high-throughput sequencing of enriched libraries and segregation analysis. We conducted functional, phylogenetic, and diversity studies of eam10 and HvLUX1 to understand the genetic control of photoperiod response in barley and to characterize the evolution of LUX-like genes within barley and across monocots and eudicots. We demonstrate that eam10 causes circadian defects and interacts with the photoperiod response gene Ppd-H1 to accelerate flowering under long and short days. The results of phylogenetic and diversity analyses indicate that HvLUX1 was under purifying selection, duplicated at the base of the grass clade, and diverged independently of LUX-like genes in other plant lineages. Taken together, these findings contribute to improved understanding of the barley circadian clock, its interaction with the photoperiod pathway, and evolution of circadian systems in barley and across monocots and eudicots. PMID:23731278

Design and performance of 10-Gb/s L-band REAM-SOA for OLT Transmitter in next generation access networks.

PubMed

Lee, Dong-Hun; Jeong, Jong Sool; Kim, Ki-Soo; Kim, Hyun-Soo; Kim, Dong Churl; Park, Mi-Ran; Han, Yong-Tak; Kwon, Oh Kee; Kwon, O-Kyun

2015-02-09

We present a 10-Gb/s L-band reflective electro-absorption modulator integrated with a semiconductor optical amplifier (REAM-SOA) having improved transmission performance at very low input power of seed light. To decrease the input power of seed light, the absorption characteristics of the REAM are adjusted to reduce the amplified spontaneous emission light returned into the SOA, suppressing the gain saturation effect of the SOA. At a considerably low input power of -16 dBm, the REAM-SOA exhibits a low transmission penalty of about 1.2 dB after 50-km SMF transmission. Over a wide input power range from -16 dBm to 5 dBm, a penalty of less than 1.6 dB is achieved at 50-km transmission.

Optical data latch

DOEpatents

Vawter, G Allen [Corrales, NM

2010-08-31

An optical data latch is formed on a substrate from a pair of optical logic gates in a cross-coupled arrangement in which optical waveguides are used to couple an output of each gate to an photodetector input of the other gate. This provides an optical bi-stability which can be used to store a bit of optical information in the latch. Each optical logic gate, which can be an optical NOT gate (i.e. an optical inverter) or an optical NOR gate, includes a waveguide photodetector electrically connected in series with a waveguide electroabsorption modulator. The optical data latch can be formed on a III-V compound semiconductor substrate (e.g. an InP or GaAs substrate) from III-V compound semiconductor layers. A number of optical data latches can be cascaded to form a clocked optical data shift register.

Mechanisms of the Third-Order Nonlinear Optical Response in Dye-Doped Polymers.

NASA Astrophysics Data System (ADS)

Poga, Constantina

Quadratic Electroabsorption is applied to thin -film solid solutions of squarylium dye molecules in poly(methyl methacrylate) polymer to study the mechanisms in the third order nonlinear optical susceptibility. The data are interpreted with the help of a generalized quadratic electrooptic response theory that includes both electronic and hindered molecular motion mechanisms. This theory predicts the tensor ratio of two independent third order susceptibility tensor components, chi_sp{3333}{(3)}/ chi_sp{1133}{(3)}, whose value distinctly characterizes the relative contribution of each mechanism. Although thickness change mechanisms have not been included in this theory, their effect on the tensor ratio chi_sp{3333 }{(3)}/chi_sp{1133} {(3)} has been taken into account for both electrostriction and electrode attraction mechanisms. We measure the tensor ratio with quadratic electroabsorption spectroscopy as a function of temperature and wavelength and find that the response is predominantly electronic at temperatures below the glass transition temperature, but at temperatures higher than the glass transition temperature both reorientational and thickness changes effects play a dominant role. In particular, the contribution of each mechanism has been found for all wavelengths in the visible and the dominant thickness change mechanism has been identified to be electrode attraction. Additionally, the real part of the third-order nonlinear susceptibility can be found through a Kramers-Kronig transformation of the experimentally measured imaginary part. The knowledge of both the real and imaginary part in the visible allows the calculation of the two-photon figure of merit (defined as the real over the imaginary part of chi^{(3) }) which is necessary for determining a material's suitability for all-optical devices. Furthermore, quadratic electroabsorption can be used to characterize the nature of the excited states which in turn can be used to understand the source of the electronic response. For the ISQ chromophore, a one-photon state (at 657nm) and a two-photon state (at 596nm) have been found, and a three-level fit based on these states has been successful in predicting the low temperature chi^{(3)}^ectrum. Quadratic electroabsorption has been proven to be a versatile tool to study the mechanisms of the third -order nonlinear optical response, to measure the electronic gamma, to study the symmetry of the excited states of a molecule and to characterize the suitability of a material for all-optical devices. In this chapter, we start by calculating the change in the imaginary part of the refractive index under the application of an electric field and proceed with connecting this change with the quantities that are experimentally measured by the quadratic electroabsorption experiment. The sample preparation and the data collection are also described.

The effect of the order in which episodic autobiographical memories versus autobiographical knowledge are shared on feelings of closeness.

PubMed

Brandon, Nicole R; Beike, Denise R; Cole, Holly E

2017-07-01

Autobiographical memories (AMs) can be used to create and maintain closeness with others [Alea, N., & Bluck, S. (2003). Why are you telling me that? A conceptual model of the social function of autobiographical memory. Memory, 11(2), 165-178]. However, the differential effects of memory specificity are not well established. Two studies with 148 participants tested whether the order in which autobiographical knowledge (AK) and specific episodic AM (EAM) are shared affects feelings of closeness. Participants read two memories hypothetically shared by each of four strangers. The strangers first shared either AK or an EAM, and then shared either AK or an EAM. Participants were randomly assigned to read either positive or negative AMs from the strangers. Findings suggest that people feel closer to those who share positive AMs in the same way they construct memories: starting with general and moving to specific.

Cryptofauna of the epilithic algal matrix on an inshore coral reef, Great Barrier Reef

NASA Astrophysics Data System (ADS)

Kramer, M. J.; Bellwood, D. R.; Bellwood, O.

2012-12-01

Composed of a collection of algae, detritus, sediment and invertebrates, the epilithic algal matrix (EAM) is an abundant and ubiquitous feature of coral reefs. Despite its prevalence, there is a paucity of information regarding its associated invertebrate fauna. The cryptofaunal invertebrate community of the EAM was quantitatively investigated in Pioneer Bay on Orpheus Island, Great Barrier Reef. Using a vacuum collection method, a diversity of organisms representing 10 different phyla were identified. Crustacea dominated the samples, with harpacticoid copepods being particularly abundant (2025 ± 132 100 cm-2; mean density ± SE). The volume of coarse particulate matter in the EAM was strongly correlated with the abundance of harpacticoid copepods. The estimated biomass of harpacticoid copepods (0.48 ± 0.05 g m-2; wet weight) suggests that this group is likely to be important for reef trophodynamics and nutrient cycling.

Selected area growth integrated wavelength converter based on PD-EAM optical logic gate

NASA Astrophysics Data System (ADS)

Bin, Niu; Jifang, Qiu; Daibing, Zhou; Can, Zhang; Song, Liang; Dan, Lu; Lingjuan, Zhao; Jian, Wu; Wei, Wang

2014-09-01

A selected area growth wavelength converter based on a PD-EAM optical logic gate for WDM application is presented, integrating an EML transmitter and a SOA-PD receiver. The design, fabrication, and DC characters were analyzed. A 2 Gb/s NRZ signal based on the C-band wavelength converted to 1555 nm with the highest extinction ratio of 7 dB was achieved and wavelength converted eye diagrams with eyes opened were presented.

Permanent polarization and charge distribution in organic light-emitting diodes (OLEDs): Insights from near-infrared charge-modulation spectroscopy of an operating OLED

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchetti, Alfred P.; Haskins, Terri L.; Young, Ralph H.

2014-03-21

Vapor-deposited Alq{sub 3} layers typically possess a strong permanent electrical polarization, whereas NPB layers do not. (Alq{sub 3} is tris(8-quinolinolato)aluminum(III); NPB is 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl.) The cause is a net orientation of the Alq{sub 3} molecules with their large dipole moments. Here we report on consequences for an organic light-emitting diode (OLED) with an NPB hole-transport layer and Alq{sub 3} electron-transport layer. The discontinuous polarization at the NPB|Alq{sub 3} interface has the same effect as a sheet of immobile negative charge there. It is more than compensated by a large concentration of injected holes (NPB{sup +}) when the OLED is running. Wemore » discuss the implications and consequences for the quantum efficiency and the drive voltage of this OLED and others. We also speculate on possible consequences of permanent polarization in organic photovoltaic devices. The concentration of NPB{sup +} was measured by charge-modulation spectroscopy (CMS) in the near infrared, where the NPB{sup +} has a strong absorption band, supplemented by differential-capacitance and current-voltage measurements. Unlike CMS in the visible, this method avoids complications from modulation of the electroluminescence and electroabsorption.« less

The Space Launch System and the Proving Ground: Pathways to Mars

NASA Astrophysics Data System (ADS)

Klaus, Kurt K.

2014-11-01

Introduction: The Space Launch System (SLS) is the most powerful rocket ever built and provides a critical heavy-lift launch capability. We focus on mission concepts relevant to NASA’s Cislunar Proving Ground and the Global Exploration Roadmap (GER).Asteroid Redirect Mission (ARM): ARM in part is a mission to the lunar vicinity. The ARM mission requirements result in system design based on a modified version of our 702 spacecraft. Including a NASA Docking System (NDS) on the Asteroid Redirect Vehicle allows for easier crewed exploration integration and execution. Exploration Augmentation Module (EAM): Crew operations at a redirected asteroid could be significantly enhanced by providing additional systems and EVA capabilities beyond those available from the Orion only. An EAM located with the asteroid would improve the science and technical return of the mission while also increasing Orion capability through resource provision, abort location and safe haven for contingencies. The EAM could be repurposed as a cislunar exploration platform that advances scientific research, enables lunar surface exploration and provides a deep space vehicle assembly and servicing site. International Space Station (ISS) industry partners have been working for the past several years on concepts for using ISS development methods and assets to support a broad range of exploration missions.Lunar Surface: The mission objectives are to provide lunar surface access for crew and cargo and to provide as much system reuse as possible. Subsequent missions to the surface can reuse the same lander and Lunar Transfer Vehicle.Mars Vicinity: The International space community has declared that our unified horizon goal is for a human mission to Mars. Translunar infrastructure and heavy lift capability are key to this approach. The moons of Mars would provide an excellent stepping stone to the surface. As a “shake-down” cruise before landing, a mission to Deimos or Phobos would test all of the systems except those needed to get to the surface and back. This test would provide confidence for the in-space transportations and crew habitat systems.

The Space Launch System and the Proving Ground: Pathways to Mars

NASA Astrophysics Data System (ADS)

Klaus, K.

2014-12-01

Introduction: The Space Launch System (SLS) is the most powerful rocket ever built and provides a critical heavy-lift launch capability. We present mission concepts relevant to NASA's Cislunar Proving Ground and the Global Exploration Roadmap (GER).Asteroid Redirect Mission (ARM): ARM in part is a mission to the lunar vicinity. The ARM mission requirements result in system design based on a modified version of our 702 spacecraft. Including a NASA Docking System (NDS) on the Asteroid Redirect Vehicle allows for easier crewed exploration integration and execution. Exploration Augmentation Module (EAM): Crew operations at a redirected asteroid could be significantly enhanced by providing additional systems and EVA capabilities beyond those available from the Orion only. An EAM located with the asteroid would improve the science and technical return of the asteroid mission while also increasing Orion capability through resource provision and providing an abort location and safe haven for contingencies. The EAM could be repurposed as a cislunar exploration platform that advances scientific research, enables lunar surface exploration and provides a deep space vehicle assembly and servicing site. International Space Station (ISS) industry partners have been working for the past several years on concepts for using ISS development methods and assets to support a broad range of missions. These concepts have matured along with planning details for NASA's SLS and Orion for a platform located in the Earth-Moon Libration (EML) system or Distant Retrograde Orbit (DRO).Lunar Surface: The mission objectives are to provide lunar surface access for crew and cargo and to provide as much reuse as possible. Subsequent missions to the surface can reuse the same lander and Lunar Transfer Vehicle.Mars Vicinity: The International space community has declared that our unified horizon goal is for a human mission to Mars. Translunar infrastructure and heavy lift capability are key to this approach. The moons of Mars would provide an excellent stepping stone to the surface. As a "shake-down" cruise before landing, a mission to Deimos or Phobos would test all of the systems except those needed to get to the surface and back. This test would provide confidence for the in-space transportations and crew habitat systems.

Alteration in Memory and Electroencephalogram Waves with Sub-acute Noise Stress in Albino Rats and Safeguarded by Scoparia dulcis.

PubMed

Loganathan, Sundareswaran; Rathinasamy, Sheeladevi

2016-01-01

Noise stress has different effects on memory and novelty and the link between them with an electroencephalogram (EEG) has not yet been reported. To find the effect of sub-acute noise stress on the memory and novelty along with EEG and neurotransmitter changes. Eight-arm maze (EAM) and Y-maze to analyze the memory and novelty by novel object test. Four groups of rats were used: Control, control treated with Scoparia dulcis extract, noise exposed, and noise exposed which received Scoparia extract. The results showed no marked difference observed between control and control treated with Scoparia extract on EAM, Y-maze, novel object test, and EEG in both prefrontal and occipital region, however, noise stress exposed rats showed significant increase in the reference memory and working memory error in EAM and latency delay, triad errors in Y-maze, and prefrontal and occipital EEG frequency rate with the corresponding increase in plasma corticosterone and epinephrine, and significant reduction in the novelty test, and significant reduction in the novelty test, amplitude of prefrontal, occipital EEG, and acetylcholine. These noise stress induced changes in EAM, Y-maze, novel object test, and neurotransmitters were significantly prevented when treated with Scoparia extract and these changes may be due to the normalizing action of Scoparia extract on the brain, which altered due to noise stress. Noise stress exposure causes EEG, behavior, and neurotransmitter alteration in the frontoparietal and occipital regions mainly involved in planning and recognition memoryOnly the noise stress exposed animals showed the significant alteration in the EEG, behavior, and neurotransmittersHowever, these noise stress induced changes in EEG behavior and neurotransmitters were significantly prevented when treated with Scoparia extractThese changes may be due to the normalizing action of Scoparia dulcis (adoptogen) on the brain which altered by noise stress. Abbreviations used: EEG: Electroencephalogram, dB: Decibel, EPI: Epinephrine, ACH: Acetylcholine, EAM: Eight-arm maze.

Alteration in Memory and Electroencephalogram Waves with Sub-acute Noise Stress in Albino Rats and Safeguarded by Scoparia dulcis

PubMed Central

Loganathan, Sundareswaran; Rathinasamy, Sheeladevi

2016-01-01

Background: Noise stress has different effects on memory and novelty and the link between them with an electroencephalogram (EEG) has not yet been reported. Objective: To find the effect of sub-acute noise stress on the memory and novelty along with EEG and neurotransmitter changes. Materials and Methods: Eight-arm maze (EAM) and Y-maze to analyze the memory and novelty by novel object test. Four groups of rats were used: Control, control treated with Scoparia dulcis extract, noise exposed, and noise exposed which received Scoparia extract. Results: The results showed no marked difference observed between control and control treated with Scoparia extract on EAM, Y-maze, novel object test, and EEG in both prefrontal and occipital region, however, noise stress exposed rats showed significant increase in the reference memory and working memory error in EAM and latency delay, triad errors in Y-maze, and prefrontal and occipital EEG frequency rate with the corresponding increase in plasma corticosterone and epinephrine, and significant reduction in the novelty test, and significant reduction in the novelty test, amplitude of prefrontal, occipital EEG, and acetylcholine. Conclusion: These noise stress induced changes in EAM, Y-maze, novel object test, and neurotransmitters were significantly prevented when treated with Scoparia extract and these changes may be due to the normalizing action of Scoparia extract on the brain, which altered due to noise stress. SUMMARY Noise stress exposure causes EEG, behavior, and neurotransmitter alteration in the frontoparietal and occipital regions mainly involved in planning and recognition memoryOnly the noise stress exposed animals showed the significant alteration in the EEG, behavior, and neurotransmittersHowever, these noise stress induced changes in EEG behavior and neurotransmitters were significantly prevented when treated with Scoparia extractThese changes may be due to the normalizing action of Scoparia dulcis (adoptogen) on the brain which altered by noise stress. Abbreviations used: EEG: Electroencephalogram, dB: Decibel, EPI: Epinephrine, ACH: Acetylcholine, EAM: Eight-arm maze PMID:27041862

Functional specialization in nucleotide sugar transporters occurred through differentiation of the gene cluster EamA (DUF6) before the radiation of Viridiplantae

PubMed Central

2011-01-01

Background The drug/metabolite transporter superfamily comprises a diversity of protein domain families with multiple functions including transport of nucleotide sugars. Drug/metabolite transporter domains are contained in both solute carrier families 30, 35 and 39 proteins as well as in acyl-malonyl condensing enzyme proteins. In this paper, we present an evolutionary analysis of nucleotide sugar transporters in relation to the entire superfamily of drug/metabolite transporters that considers crucial intra-protein duplication events that have shaped the transporters. We use a method that combines the strengths of hidden Markov models and maximum likelihood to find relationships between drug/metabolite transporter families, and branches within families. Results We present evidence that the triose-phosphate transporters, domain unknown function 914, uracil-diphosphate glucose-N-acetylglucosamine, and nucleotide sugar transporter families have evolved from a domain duplication event before the radiation of Viridiplantae in the EamA family (previously called domain unknown function 6). We identify previously unknown branches in the solute carrier 30, 35 and 39 protein families that emerged simultaneously as key physiological developments after the radiation of Viridiplantae, including the "35C/E" branch of EamA, which formed in the lineage of T. adhaerens (Animalia). We identify a second cluster of DMTs, called the domain unknown function 1632 cluster, which has non-cytosolic N- and C-termini, and thus appears to have been formed from a different domain duplication event. We identify a previously uncharacterized motif, G-X(6)-G, which is overrepresented in the fifth transmembrane helix of C-terminal domains. We present evidence that the family called fatty acid elongases are homologous to transporters, not enzymes as had previously been thought. Conclusions The nucleotide sugar transporters families were formed through differentiation of the gene cluster EamA (domain unknown function 6) before Viridiplantae, showing for the first time the significance of EamA. PMID:21569384

Integration of electro-anatomical and imaging data of the left ventricle: An evaluation framework.

PubMed

Soto-Iglesias, David; Butakoff, Constantine; Andreu, David; Fernández-Armenta, Juan; Berruezo, Antonio; Camara, Oscar

2016-08-01

Integration of electrical and structural information for scar characterization in the left ventricle (LV) is a crucial step to better guide radio-frequency ablation therapies, which are usually performed in complex ventricular tachycardia (VT) cases. This integration requires finding a common representation where to map the electrical information from the electro-anatomical map (EAM) surfaces and tissue viability information from delay-enhancement magnetic resonance images (DE-MRI). However, the development of a consistent integration method is still an open problem due to the lack of a proper evaluation framework to assess its accuracy. In this paper we present both: (i) an evaluation framework to assess the accuracy of EAM and imaging integration strategies with simulated EAM data and a set of global and local measures; and (ii) a new integration methodology based on a planar disk representation where the LV surface meshes are quasi-conformally mapped (QCM) by flattening, allowing for simultaneous visualization and joint analysis of the multi-modal data. The developed evaluation framework was applied to estimate the accuracy of the QCM-based integration strategy on a benchmark dataset of 128 synthetically generated ground-truth cases presenting different scar configurations and EAM characteristics. The obtained results demonstrate a significant reduction in global overlap errors (50-100%) with respect to state-of-the-art integration techniques, also better preserving the local topology of small structures such as conduction channels in scars. Data from seventeen VT patients were also used to study the feasibility of the QCM technique in a clinical setting, consistently outperforming the alternative integration techniques in the presence of sparse and noisy clinical data. The proposed evaluation framework has allowed a rigorous comparison of different EAM and imaging data integration strategies, providing useful information to better guide clinical practice in complex cardiac interventions. Copyright © 2016 Elsevier B.V. All rights reserved.

Data Systems Task Analysis.

DTIC Science & Technology

1979-08-01

WHAT YOU DO IN YOUR PRESENT JOB. IdiS IS hQ A E&T. NEITHER YCU, YOUR CCMMANDER, NOR YOUR UNIT WILL BE EVALUATED , IN ANY WAY, CN THE INFORMATICN YCU...ACCOLNTING MACHINE (PCAM) OPERATOR 336. EAM/PCAM SUPERVISOR 231. EAM/PCAM WIRING TECI-NICIAN )38. EQUIPMENT MANAGEMENT TECFNICIAN 339. EVALUATION AND...R RAMO .4 12. BUNKER RAMC 13) 13. BUNKER RAMO 2)) 14. aJNKER RAMU 1563 15. BUhROdGHS 263 16. BuRROUGHS B d)) 17. BURROUGHS b35 .J 18. BjRROUGHS 847

Wannier-Stark localization of a strongly coupled asymmetric double-well GaAs/AlAs superlattice

NASA Astrophysics Data System (ADS)

Kawashima, Kenji; Matsumoto, Takeshi; Arima, Kiyotoku; Ohsumi, Takahiro; Nogami, Takamitsu; Satoh, Kazuo; Fujiwara, Kenzo

2000-06-01

A novel new type of superlattice (SL) structure which consists of strongly coupled asymmetric double-well (ADW) in one period have been investigated to introduce a new degree of freedom for the device funtionality. The GaAs/A1As ADS-SL contained in a p-i-n diode structure was grown by molecular beam epitaxy, and the electroabsorption properties were measured by low temperature photocurrent spectroscopy. It is found that the introduction of the confinement potential asymmetry with respect to electric field will lead to the selectivity of spatially indirect Stark-ladder transitions associated with two different types of the localized hole states, thus providing a new way of modulating the oscillator strengths. Assignment of the possible optical transitions from the miniband to the Stark-ladder regimes as a function of field strength is elucidated in detail by transfer matrix calculations.

Analysis of digital images into energy-angular momentum modes.

PubMed

Vicent, Luis Edgar; Wolf, Kurt Bernardo

2011-05-01

The measurement of continuous wave fields by a digital (pixellated) screen of sensors can be used to assess the quality of a beam by finding its formant modes. A generic continuous field F(x, y) sampled at an N × N Cartesian grid of point sensors on a plane yields a matrix of values F(q(x), q(y)), where (q(x), q(y)) are integer coordinates. When the approximate rotational symmetry of the input field is important, one may use the sampled Laguerre-Gauss functions, with radial and angular modes (n, m), to analyze them into their corresponding coefficients F(n, m) of energy and angular momentum (E-AM). The sampled E-AM modes span an N²-dimensional space, but are not orthogonal--except for parity. In this paper, we propose the properly orthonormal "Laguerre-Kravchuk" discrete functions Λ(n, m)(q(x), q(y)) as a convenient basis to analyze the sampled beams into their E-AM polar modes, and with them synthesize the input image exactly.

Impact of GFZ's Effective Angular Momentum Forecasts on Polar Motion Prediction

NASA Astrophysics Data System (ADS)

Dill, Robert; Dobslaw, Henryk

2017-04-01

The Earth System Modelling group at GeoForschungsZentrum (GFZ) Potsdam offers now 6-day forecasts of Earth rotation excitation due to atmospheric, oceanic, and hydrologic angular momentum changes that are consistent with its 40 years-long EAM series. Those EAM forecasts are characterized by an improved long-term consistency due to the introduction of a time-invariant high-resolution reference topography into the AAM processing that accounts for occasional NWP model changes. In addition, all tidal signals from both atmosphere and ocean have been separated, and the temporal resolution of both AAM and OAM has been increased to 3 hours. Analysis of an extended set of EAM short-term hindcasts revealed positive prediction skills for up to 6 days into the future when compared to a persistent forecast. Whereas UT1 predictions in particular rely on an accurate AAM forecast, skillfull polar motion prediction requires high-quality OAM forecasts as well. We will present in this contribution the results from a multi-year hindcast experiment, demonstrating that the polar motion prediction as currently available from Bulletin A can be improved in particular for lead-times between 2 and 5 days by incorporating OAM forecasts. We will also report about early results obtained at Observatoire de Paris to predict polar motion from the integration of GFZ's 6-day EAM forecasts into the Liouville equation in a routine setting, that fully takes into account the operational latencies of all required input products.

Electromodulation spectroscopy of sc and fcc phase TlCl and TlBr

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClelland, J.F.

1976-06-01

Electromodulation measurements were made on these compounds and the spectra were reduced to the electric field induced changes in the dielectric function. The results indicate the importance of photocarrier effects in both theory and experiment in the electromodulation of exciton states. In the future, calculations should include the effect of photocarriers on the field seen by the exciton and experimentally samples should be developed with known and reproducible photocarrier properties with temperature control between liquid helium and nitrogen temperatures and bipolar modulation fields. The abnormal (fcc) phase electroabsorption (EA) measurements have demonstrated the usefulness of the modulation method in resolvingmore » exciton states by determining the n = 2 energy in TlBr. This has enabled a number of quantities to be calculated from the Wannier exciton model. The resolution of the n = 2 energy in TlCl is probably also possible with an EA measurement and patience with the signal to noise problem. The ..cap alpha.. and ..beta.. features are still unassigned but the unusual EA lineshape and sample preparation sensitivity found in this investigation may prove useful in making definitive assignments in conjunction with future work.« less

The influence of climate regime shifts on the marine environment and ecosystems in the East Asian Marginal Seas and their mechanisms

NASA Astrophysics Data System (ADS)

Kun Jung, Hae; Rahman, SM Mustafizur; Kang, Chang-Keun; Park, Se-Young; Heon Lee, Sang; Je Park, Hyun; Kim, Hyun-Woo; Il Lee, Chung

2017-09-01

Step changes to seawater temperature (SWT) in the East Asian marginal seas (EAMS) are associated with three recent climate regime shifts (CRS) occurring in the mid-1970s, late 1980s, and late 1990s, but the responses of the ocean conditions and marine ecosystems had regional differences. A step change in SWT in the East China Sea (ECS) was detected after the CRS of the 1970s as were step changes in the North Pacific Index (NPI), Pacific Decadal Oscillation Index (PDOI), and East Asian Winter Monsoon Index (EAWMI). SWT in the ECS decreased with decreasing warm water volume transport into the EAMS and a strong monsoon, but step changes in SWT in other regions were not detected as clearly. After the CRS of the 1980s, SWT in all EAMS increased rapidly with step changes detected in all five climate indices examined. These changes were associated with a weak winter monsoon, increasing surface air temperature (SAT), and increasing warm water volume transport into the EAMS. However, after the CRS of the 1990s, a decrease in SWT around the EAMS was detected in the northern part of East China Sea (NECS), and the ECS with step changes also in the EAWMI and the Arctic Oscillation Index (AOI). In contrast, SWT in the East Sea/Sea of Japan (EJS) and the Yellow Sea (YS) continuously increased during this time. Long-term changes in zooplankton biomass were affected by regional differences in the responses of atmospheric and oceanic variability to CRSs. Specifically, long-term changes in the timing of peaks in zooplankton abundances exhibited differences. During warm periods (e.g. after the 1980s CRS) in the EJS, the amount of zooplankton biomass in October increased, while in February it decreased. On the contrary, in the YS and the NECS, the peaks of October and June in zooplankton biomass occurred during cold periods (after the 1970s and 1990s CRS). Major fisheries resources also responded to the three CRSs, although warm and cold water species responded differently to changes in oceanographic conditions in regional spawning grounds.

The neuropeptide cortistatin attenuates experimental autoimmune myocarditis via inhibition of cardiomyogenic T cell‐driven inflammatory responses

PubMed Central

Delgado‐Maroto, Virginia; Falo, Clara P; Forte‐Lago, Irene; Adan, Norma; Morell, Maria; Maganto‐Garcia, Elena; Robledo, Gema; O'Valle, Francisco; Lichtman, Andrew H; Gonzalez‐Rey, Elena

2017-01-01

Background and purpose Myocarditis is an inflammatory and autoimmune cardiovascular disease that causes dilated myocardiopathy and is responsible for high morbidity and mortality worldwide. Cortistatin is a neuropeptide produced by neurons and cells of the immune and vascular systems. Besides its action in locomotor activity and sleep, cortistatin inhibits inflammation in different experimental models of autoimmune diseases. However, its role in inflammatory cardiovascular disorders is unexplored. Here, we investigated the therapeutic effects of cortistatin in a well‐established preclinical model of experimental autoimmune myocarditis (EAM). Experimental Approach We induced EAM by immunization with a fragment of cardiac myosin in susceptible Balb/c mice. Cortistatin was administered i.p. starting 7, 11 or 15 days after EAM induction. At day 21, we evaluated heart hypertrophy, myocardial injury, cardiac inflammatory infiltration and levels of serum and cardiac inflammatory cytokines, cortistatin and autoantibodies. We determined proliferation and cytokine production by heart draining lymph node cells in response to cardiac myosin restimulation. Key Results Systemic injection of cortistatin during the effector phase of the disease significantly reduced its prevalence and signs of heart hypertrophy and injury (decreased the levels of brain natriuretic peptide) and impaired myocardial inflammatory cell infiltration. This effect was accompanied by a reduction in self‐antigen‐specific T‐cell responses in lymph nodes and in the levels of cardiomyogenic antibodies and inflammatory cytokines in serum and myocardium. Finally, we found a positive correlation between cardiac and systemic cortistatin levels and EAM severity. Conclusions and Implications Cortistatin emerges as a new candidate to treat inflammatory dilated cardiomyopathy. PMID:27922195

Evaluation of a high-resolution patient-specific model of the electrically stimulated cochlea

NASA Astrophysics Data System (ADS)

Cakir, Ahmet; Dwyer, Robert T.; Noble, Jack H.

2017-03-01

Cochlear implants (CIs) are considered standard treatment for patients who experience sensorineural hearing loss. Although these devices have been remarkably successful at restoring hearing, it is rare to achieve natural fidelity, and many patients experience poor outcomes. Our group has developed the first image-guided CI programming (IGCIP) technique where the positions of the electrodes are found in CT images and used to estimate neural activation patterns, which is unique information that audiologists can use to define patient-specific processor settings. In our current system, neural activation is estimated using only the distance from each electrode to the neural activation sites. This approach might be less accurate than using a high-resolution electro-anatomical model (EAM) of the electrically stimulated cochlea to perform physics-based estimation of neural activation. In this work, we propose a patientcustomized EAM approach where the EAM is spatially and electrically adapted to a patient-specific configuration. Spatial adaptation is done through non-rigid registration of the model with the patient CT image. Electrical adaptation is done by adjusting tissue resistivity parameters so that the intra-cochlear voltage distributions predicted by the model best match those directly measured for the patient via their implant. We demonstrated our approach for N=7 patients. We found that our approach results in mean percent differences between direct and simulated measurements of voltage distributions of 11%. In addition, visual comparison shows the simulated and measured voltage distributions are qualitatively in good agreement. This represents a crucial step toward developing and validating the first in vivo patient-specific cochlea EAMs.

EXOS research on force-reflecting controllers

NASA Astrophysics Data System (ADS)

Eberman, Brian S.; An, Bin

1993-03-01

EXOS has developed two state of the art prototype master controllers for controlling robot hands and manipulators under the Small Business Innovation Research (SBIR) program with NASA. One such device is a two degree-of-freedom Sensing and Force Reflecting Exoskeleton (SAFiRE) worn on the operator's hand. The device measures the movement of the index finger and reflects the interaction forces between the slave robot and the environment to the human finger. The second device is a position sensing Exoskeleton ArmMaster (EAM) worn by a human operator. The device simultaneously tracks the motions of the operator's three DOF shoulder and two DOF elbow. Both of these devices are currently used to control robots at NASA. We are currently developing a full fingered SAFiRE and a position sensing and force reflecting EAM under two second phase SBIR grants with NASA. This paper will include discussions of: (1) the design of the current prototypes, (2) kinematics of the EAM and force control of the SAFiRE, (3) design issues that must be addressed in developing more advanced versions, and (4) our progress to date in addressing these issues.

Study on high-resolution representation of terraces in Shanxi Loess Plateau area

NASA Astrophysics Data System (ADS)

Zhao, Weidong; Tang, Guo'an; Ma, Lei

2008-10-01

A new elevation points sampling method, namely TIN-based Sampling Method (TSM) and a new visual method called Elevation Addition Method (EAM), are put forth for representing the typical terraces in Shanxi loess plateau area. The DEM Feature Points and Lines Classification (DEPLC) put forth by the authors in 2007 is perfected for depicting the main path in the study area. The EAM is used to visualize the terraces and the path in the study area. 406 key elevation points and 15 feature constrained lines sampled by this method are used to construct CD-TINs which can depict the terraces and path correctly and effectively. Our case study shows that the new sampling method called TSM is reasonable and feasible. The complicated micro-terrains like terraces and path can be represented with high resolution and high efficiency successfully by use of the perfected DEPLC, TSM and CD-TINs. And both the terraces and the main path are visualized very well by use of EAM even when the terrace height is not more than 1m.

Implementation of EAM and FS potentials in HOOMD-blue

NASA Astrophysics Data System (ADS)

Yang, Lin; Zhang, Feng; Travesset, Alex; Wang, Caizhuang; Ho, Kaiming

HOOMD-blue is a general-purpose software to perform classical molecular dynamics simulations entirely on GPUs. We provide full support for EAM and FS type potentials in HOOMD-blue, and report accuracy and efficiency benchmarks, including comparisons with the LAMMPS GPU package. Two problems were selected to test the accuracy: the determination of the glass transition temperature of Cu64.5Zr35.5 alloy using an FS potential and the calculation of pair distribution functions of Ni3Al using an EAM potential. In both cases, the results using HOOMD-blue are indistinguishable from those obtained by the GPU package in LAMMPS within statistical uncertainties. As tests for time efficiency, we benchmark time-steps per second using LAMMPS GPU and HOOMD-blue on one NVIDIA Tesla GPU. Compared to our typical LAMMPS simulations on one CPU cluster node which has 16 CPUs, LAMMPS GPU can be 3-3.5 times faster, and HOOMD-blue can be 4-5.5 times faster. We acknowledge the support from Laboratory Directed Research and Development (LDRD) of Ames Laboratory.

A Case for Application Oblivious Energy-Efficient MPI Runtime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venkatesh, Akshay; Vishnu, Abhinav; Hamidouche, Khaled

Power has become the major impediment in designing large scale high-end systems. Message Passing Interface (MPI) is the {\\em de facto} communication interface used as the back-end for designing applications, programming models and runtime for these systems. Slack --- the time spent by an MPI process in a single MPI call --- provides a potential for energy and power savings, if an appropriate power reduction technique such as core-idling/Dynamic Voltage and Frequency Scaling (DVFS) can be applied without perturbing application's execution time. Existing techniques that exploit slack for power savings assume that application behavior repeats across iterations/executions. However, an increasingmore » use of adaptive, data-dependent workloads combined with system factors (OS noise, congestion) makes this assumption invalid. This paper proposes and implements Energy Aware MPI (EAM) --- an application-oblivious energy-efficient MPI runtime. EAM uses a combination of communication models of common MPI primitives (point-to-point, collective, progress, blocking/non-blocking) and an online observation of slack for maximizing energy efficiency. Each power lever incurs time overhead, which must be amortized over slack to minimize degradation. When predicted communication time exceeds a lever overhead, the lever is used {\\em as soon as possible} --- to maximize energy efficiency. When mis-prediction occurs, the lever(s) are used automatically at specific intervals for amortization. We implement EAM using MVAPICH2 and evaluate it on ten applications using up to 4096 processes. Our performance evaluation on an InfiniBand cluster indicates that EAM can reduce energy consumption by 5--41\\% in comparison to the default approach, with negligible (less than 4\\% in all cases) performance loss.« less

Myocardial Scar Imaging by Standard Single-Energy and Dual-Energy Late Enhancement Computed Tomography: Comparison to Pathology and Electroanatomical Map in an Experimental Chronic Infarct Porcine Model

PubMed Central

Truong, Quynh A.; Thai, Wai-ee; Wai, Bryan; Cordaro, Kevin; Cheng, Teresa; Beaudoin, Jonathan; Xiong, Guanglei; Cheung, Jim W.; Altman, Robert; Min, James K.; Singh, Jagmeet P.; Barrett, Conor D.; Danik, Stephan

2015-01-01

Background Myocardial scar is a substrate for ventricular tachycardia and sudden cardiac death. Late enhancement computed tomography (CT) imaging can detect scar, but it remains unclear whether newer late enhancement dual-energy (LE-DECT) acquisition has benefit over standard single-energy late enhancement (LE-CT). Objective We aim to compare late enhancement CT using newer LE-DECT acquisition and single-energy LE-CT acquisitions to pathology and electroanatomical map (EAM) in an experimental chronic myocardial infarction (MI) porcine study. Methods In 8 chronic MI pigs (59±5 kg), we performed dual-source CT, EAM, and pathology. For CT imaging, we performed 3 acquisitions at 10 minutes post-contrast: LE-CT 80 kV, LE-CT 100 kV, and LE-DECT with two post-processing software settings. Results Of the sequences, LE-CT 100 kV provided the best contrast-to-noise ratio (all p≤0.03) and correlation to pathology for scar (ρ=0.88). While LE-DECT overestimated scar (both p=0.02), LE-CT images did not (both p=0.08). On a segment basis (n=136), all CT sequences had high specificity (87–93%) and modest sensitivity (50–67%), with LE-CT 100 kV having the highest specificity of 93% for scar detection compared to pathology and agreement with EAM (κ 0.69). Conclusions Standard single-energy LE-CT, particularly 100kV, matched better to pathology and EAM than dual-energy LE-DECT for scar detection. Larger human trials as well as more technical-based studies that optimize varying different energies with newer hardware and software are warranted. PMID:25977115

Diffusion on Cu surfaces

NASA Technical Reports Server (NTRS)

Karimi, Majid

1993-01-01

Understanding surface diffusion is essential in understanding surface phenomena, such as crystal growth, thin film growth, corrosion, physisorption, and chemisorption. Because of its importance, various experimental and theoretical efforts have been directed to understand this phenomena. The Field Ion Microscope (FIM) has been the major experimental tool for studying surface diffusion. FIM have been employed by various research groups to study surface diffusion of adatoms. Because of limitations of the FIM, such studies are only limited to a few surfaces: nickel, platinum, aluminum, iridium, tungsten, and rhodium. From the theoretical standpoint, various atomistic simulations are performed to study surface diffusion. In most of these calculations the Embedded Atom Method (EAM) along with the molecular static (MS) simulation are utilized. The EAM is a semi-empirical approach for modeling the interatomic interactions. The MS simulation is a technique for minimizing the total energy of a system of particles with respect to the positions of its particles. One of the objectives of this work is to develop the EAM functions for Cu and use them in conjunction with the molecular static (MS) simulation to study diffusion of a Cu atom on a perfect as well as stepped Cu(100) surfaces. This will provide a test of the validity of the EAM functions on Cu(100) surface and near the stepped environments. In particular, we construct a terrace-ledge-kink (TLK) model and calculate the migration energies of an atom on a terrace, near a ledge site, near a kink site, and going over a descending step. We have also calculated formation energies of an atom on the bare surface, a vacancy in the surface, a stepped surface, and a stepped-kink surface. Our results are compared with the available experimental and theoretical results.

Ultrafast intersystem-crossing in platinum containing π-conjugated polymers with tunable spin-orbit coupling.

PubMed

Sheng, C-X; Singh, S; Gambetta, A; Drori, T; Tong, M; Tretiak, S; Vardeny, Z V

2013-01-01

The development of efficient organic light-emitting diodes (OLED) and organic photovoltaic cells requires control over the dynamics of spin sensitive excitations. Embedding heavy metal atoms in π-conjugated polymer chains enhances the spin-orbit coupling (SOC), and thus facilitates intersystem crossing (ISC) from the singlet to triplet manifolds. Here we use various nonlinear optical spectroscopies such as two-photon absorption and electroabsorption in conjunction with electronic structure calculations, for studying the energies, emission bands and ultrafast dynamics of spin photoexcitations in two newly synthesized π-conjugated polymers that contain intrachain platinum (Pt) atoms separated by one (Pt-1) or three (Pt-3) organic spacer units. The controllable SOC in these polymers leads to a record ISC time of <~1 ps in Pt-1 and ~6 ps in Pt-3. The tunable ultrafast ISC rate modulates the intensity ratio of the phosphorescence and fluorescence emission bands, with potential applications for white OLEDs.

Over-the-air in-band full-duplex system with hybrid RF optical and baseband digital self-interference cancellation

NASA Astrophysics Data System (ADS)

Zhang, Yunhao; Li, Longsheng; Bi, Meihua; Xiao, Shilin

2017-12-01

In this paper, we propose a hybrid analog optical self-interference cancellation (OSIC) and baseband digital SIC (DSIC) system for over-the-air in-band full-duplex (IBFD) wireless communication. Analog OSIC system is based on optical delay line, electro-absorption modulation lasers (EMLs) and balanced photodetector (BPD), which has the properties of high adjusting precision and broad processing bandwidth. With the help of baseband DSIC, the cancellation depth limitation of OSIC can be mitigated so as to achieve deeper total SIC depth. Experimental results show about 20-dB depth by OSIC and 10-dB more depth by DSIC over 1GHz broad baseband, so that the signal of interest (SOI) overlapped by wideband self-interference (SI) signal is better recovered compared to the IBFD system with OSIC or DSIC only. The hybrid of OSIC and DSIC takes advantages of the merits of optical devices and digital processors to achieve deep cancellation depth over broad bandwidth.

Symmetric 40-Gb/s TWDM-PON with 51-dB loss budget by using a single SOA as preamplifier, booster and format converter in ONU.

PubMed

Li, Zhengxuan; Yi, Lilin; Hu, Weisheng

2014-10-06

In this paper, we propose to use a semiconductor optical amplifier (SOA) in the optical network unit (ONU) to improve the loss budget in time and wavelength division multiplexed-passive optical network (TWDM-PON) systems. The SOA boosts the upstream signal to increase the output power of the electro-absorption modulated laser (EML) and simultaneously pre-amplifies the downstream signal for sensitivity improvement. The penalty caused by cross gain modulation (XGM) effect is negligible due to the low extinction ratio (ER) of upstream signal and the large wavelength difference between upstream and downstream links. In order to achieve a higher output power, the SOA is driven into its saturation region, where the self-phase modulation (SPM) effect converts the intensity into phase information and realizes on-off-keying (OOK) to phase-shifted-keying (PSK) format conversion. In this way, the pattern effect is eliminated, which releases the requirement of gain-clamping on SOA. To further improve the loss budget of upstream link, an Erbium doped fiber amplifier (EDFA) is used in the optical line terminal (OLT) to pre-amplify the received signal. For the downstream direction, directly modulated laser (DML) is used as the laser source. Taking advantage of its carrier-less characteristic, directly modulated signal shows high tolerance to fiber nonlinearity, which could support a downstream launch power as high as + 16 dBm per channel. In addition, the signal is pre-amplified by the SOA in ONU before being detected, so the sensitivity limitation for downstream link is also removed. As a result, a truly passive symmetric 40-Gb/s TWDM-PON was demonstrated, achieving a link loss budget of 51 dB.

Performance Comparison of 112-Gb/s DMT, Nyquist PAM4, and Partial-Response PAM4 for Future 5G Ethernet-Based Fronthaul Architecture

NASA Astrophysics Data System (ADS)

Eiselt, Nicklas; Muench, Daniel; Dochhan, Annika; Griesser, Helmut; Eiselt, Michael; Olmos, Juan Jose Vegas; Monroy, Idelfonso Tafur; Elbers, Joerg-Peter

2018-05-01

For a future 5G Ethernet-based fronthaul architecture, 100G trunk lines of a transmission distance up to 10 km standard single mode fiber (SSMF) in combination with cheap grey optics to daisy chain cell site network interfaces are a promising cost- and power-efficient solution. For such a scenario, different intensity modulation and direct detect (IMDD) Formats at a data rate of 112 Gb/s, namely Nyquist four-level pulse amplitude modulation (PAM4), discrete multi-tone Transmission (DMT) and partial-response (PR) PAM4 are experimentally investigated, using a low-cost electro-absorption modulated laser (EML), a 25G driver and current state-of-the-art high Speed 84 GS/s CMOS digital-to-analog converter (DAC) and analog-to-digital converter (ADC) test chips. Each modulation Format is optimized independently for the desired scenario and their digital signal processing (DSP) requirements are investigated. The performance of Nyquist PAM4 and PR PAM4 depend very much on the efficiency of pre- and post-equalization. We show the necessity for at least 11 FFE-taps for pre-emphasis and up to 41 FFE coefficients at the receiver side. In addition, PR PAM4 requires an MLSE with four states to decode the signal back to a PAM4 signal. On the contrary, bit- and power-loading (BL, PL) is crucial for DMT and an FFT length of at least 512 is necessary. With optimized parameters, all Modulation formats result in a very similar performances, demonstrating a transmission distance of up to 10 km over SSMF with bit error rates (BERs) below a FEC threshold of 4.4E-3, allowing error free transmission.

A method of solid-solid phase equilibrium calculation by molecular dynamics

NASA Astrophysics Data System (ADS)

Karavaev, A. V.; Dremov, V. V.

2016-12-01

A method for evaluation of solid-solid phase equilibrium curves in molecular dynamics simulation for a given model of interatomic interaction is proposed. The method allows to calculate entropies of crystal phases and provides an accuracy comparable with that of the thermodynamic integration method by Frenkel and Ladd while it is much simpler in realization and less intense computationally. The accuracy of the proposed method was demonstrated in MD calculations of entropies for EAM potential for iron and for MEAM potential for beryllium. The bcc-hcp equilibrium curves for iron calculated for the EAM potential by the thermodynamic integration method and by the proposed one agree quite well.

Rapid production of hollow SS316 profiles by extrusion based additive manufacturing

NASA Astrophysics Data System (ADS)

Rane, Kedarnath; Cataldo, Salvatore; Parenti, Paolo; Sbaglia, Luca; Mussi, Valerio; Annoni, Massimiliano; Giberti, Hermes; Strano, Matteo

2018-05-01

Complex shaped stainless steel tubes are often required for special purpose biomedical equipment. Nevertheless, traditional manufacturing technologies, such as extrusion, lack the ability to compete in a market of customized complex components because of associated expenses towards tooling and extrusion presses. To rapid manufacture few of such components with low cost and high precision, a new Extrusion based Additive Manufacturing (EAM) process, is proposed in this paper, and as an example, short stainless steel 316L complex shaped and sectioned tubes were prepared by EAM. Several sample parts were produced using this process; the dimensional stability, surface roughness and chemical composition of sintered samples were investigated to prove process competence. The results indicate that feedstock with a 316L particle content of 92.5 wt. % can be prepared with a sigma blade mixing, whose rheological behavior is fit for EAM. The green samples have sufficient strength to handle them for subsequent treatments. The sintered samples considerably shrunk to designed dimensions and have a homogeneous microstructure to impart mechanical strength. Whereas, maintaining comparable dimensional accuracy and chemical composition which are required for biomedical equipment still need iterations, a kinematic correction and modification in debinding cycle was proposed.

Electrochemical and genomic analysis of novel electroactive isolates obtained via potentiostatic enrichment from tropical sediment

NASA Astrophysics Data System (ADS)

Doyle, Lucinda E.; Yung, Pui Yi; Mitra, Sumitra D.; Wuertz, Stefan; Williams, Rohan B. H.; Lauro, Federico M.; Marsili, Enrico

2017-07-01

Enrichment of electrochemically-active microorganisms (EAM) to date has mostly relied on microbial fuel cells fed with wastewater. This study aims to enrich novel EAM by exposing tropical sediment, not frequently reported in the literature, to sustained anodic potentials. Voltamperometric techniques and electrochemical impedance spectroscopy, performed over a wide range of potentials, characterise extracellular electron transfer (EET) over time. Applied potential is found to affect biofilm electrochemical signature. Geobacter metallireducens is heavily enriched on the electrodes, as determined by metagenomic and metatranscriptomic analysis, in the first report of the species in a lactate-fed system. Two novel isolates are grown in pure culture from the enrichment, identified by 16S rRNA gene sequencing as Aeromonas and Enterobacter, respectively. The names proposed are Aeromonas sp. CL-1 and Enterobacter sp. EA-1. Both isolates are capable of EET on carbon felt and screen-printed carbon electrodes without the addition of exogenous redox mediators. Enterobacter sp. EA-1 can also perform mediated electron transfer using the soluble redox mediator 2-hydroxy-1,4-naphthoquinone (HNQ). Both isolates are able to use acetate and lactate as electron donors. This work outlines a comprehensive methodology for characterising novel EAM from unconventional inocula.

Navigation for fluoroscopy-guided cryo-balloon ablation procedures of atrial fibrillation

NASA Astrophysics Data System (ADS)

Bourier, Felix; Brost, Alexander; Kleinoeder, Andreas; Kurzendorfer, Tanja; Koch, Martin; Kiraly, Attila; Schneider, Hans-Juergen; Hornegger, Joachim; Strobel, Norbert; Kurzidim, Klaus

2012-02-01

Atrial fibrillation (AFib), the most common arrhythmia, has been identified as a major cause of stroke. The current standard in interventional treatment of AFib is the pulmonary vein isolation (PVI). PVI is guided by fluoroscopy or non-fluoroscopic electro-anatomic mapping systems (EAMS). Either classic point-to-point radio-frequency (RF)- catheter ablation or so-called single-shot-devices like cryo-balloons are used to achieve electrically isolation of the pulmonary veins and the left atrium (LA). Fluoroscopy-based systems render overlay images from pre-operative 3-D data sets which are then merged with fluoroscopic imaging, thereby adding detailed 3-D information to conventional fluoroscopy. EAMS provide tracking and visualization of RF catheters by means of electro-magnetic tracking. Unfortunately, current navigation systems, fluoroscopy-based or EAMS, do not provide tools to localize and visualize single shot devices like cryo-balloon catheters in 3-D. We present a prototype software for fluoroscopy-guided ablation procedures that is capable of superimposing 3-D datasets as well as reconstructing cyro-balloon catheters in 3-D. The 3-D cyro-balloon reconstruction was evaluated on 9 clinical data sets, yielded a reprojected 2-D error of 1.72 mm +/- 1.02 mm.

The Embedded Atom Model and large-scale MD simulation of tin under shock loading

NASA Astrophysics Data System (ADS)

Sapozhnikov, F. A.; Ionov, G. V.; Dremov, V. V.; Soulard, L.; Durand, O.

2014-05-01

The goal of the work was to develop an interatomic potential, that can be used in large-scale classical MD simulations to predict tin properties near the melting curve, the melting curve itself, and the kinetics of melting and solidification when shock and ramp loading. According to phase diagram, shocked tin melts from bcc phase, and since the main objective was to investigate melting, the EAM was parameterized for bcc phase. The EAM was optimized using isothermal compression data (experimental at T=300 K and ab-initio at T=0 K for bcc, fcc, bct structures), experimental and QMD data on the Hugoniot and on the melting at elevated pressures. The Hugoniostat calculations centred at β-tin at ambient conditions showed that the calculated Hugoniot is in good agreement with experimental and QMD data above p-bct transition pressure. Calculations of overcooled liquid in pressure range corresponding to bcc phase showed crystallization into bcc phase. Since the principal Hugoniot of tin originates from the β-tin that is not described by this EAM the special initial state of bcc samples was constructed to perform large-scale MD simulations of shock loading.

Quadratic electro-optic effects and electro-absorption process in multilayer nanoshells

NASA Astrophysics Data System (ADS)

Bahari, Ali; Rahimi Moghadam, Fereshteh

2011-07-01

In this corrigendum, the authors would like to report typographic errors in the first name of the second author and in equation 7. The details of these errors can be found in the PDF. The authors would like to express their sincere apologies for these errors in the article.

Coral transplantation triggers shift in microbiome and promotion of coral disease associated potential pathogens

PubMed Central

Casey, Jordan M.; Connolly, Sean R.; Ainsworth, Tracy D.

2015-01-01

By cultivating turf algae and aggressively defending their territories, territorial damselfishes in the genus Stegastes play a major role in shaping coral-algal dynamics on coral reefs. The epilithic algal matrix (EAM) inside Stegastes’ territories is known to harbor high abundances of potential coral disease pathogens. To determine the impact of territorial grazers on coral microbial assemblages, we established a coral transplant inside and outside of Stegastes’ territories. Over the course of one year, the percent mortality of transplanted corals was monitored and coral samples were collected for microbial analysis. As compared to outside damselfish territories, Stegastes were associated with a higher rate of mortality of transplanted corals. However, 16S rDNA sequencing revealed that territorial grazers do not differentially impact the microbial assemblage of corals exposed to the EAM. Regardless of Stegastes presence or absence, coral transplantation resulted in a shift in the coral-associated microbial community and an increase in coral disease associated potential pathogens. Further, transplanted corals that suffer low to high mortality undergo a microbial transition from a microbiome similar to that of healthy corals to that resembling the EAM. These findings demonstrate that coral transplantation significantly impacts coral microbial communities, and transplantation may increase susceptibility to coral disease. PMID:26144865

Scaling vectors of attoJoule per bit modulators

NASA Astrophysics Data System (ADS)

Sorger, Volker J.; Amin, Rubab; Khurgin, Jacob B.; Ma, Zhizhen; Dalir, Hamed; Khan, Sikandar

2018-01-01

Electro-optic modulation performs the conversion between the electrical and optical domain with applications in data communication for optical interconnects, but also for novel optical computing algorithms such as providing nonlinearity at the output stage of optical perceptrons in neuromorphic analog optical computing. While resembling an optical transistor, the weak light-matter-interaction makes modulators 105 times larger compared to their electronic counterparts. Since the clock frequency for photonics on-chip has a power-overhead sweet-spot around tens of GHz, ultrafast modulation may only be required in long-distance communication, not for short on-chip links. Hence, the search is open for power-efficient on-chip modulators beyond the solutions offered by foundries to date. Here, we show scaling vectors towards atto-Joule per bit efficient modulators on-chip as well as some experimental demonstrations of novel plasmonic modulators with sub-fJ/bit efficiencies. Our parametric study of placing different actively modulated materials into plasmonic versus photonic optical modes shows that 2D materials overcompensate their miniscule modal overlap by their unity-high index change. Furthermore, we reveal that the metal used in plasmonic-based modulators not only serves as an electrical contact, but also enables low electrical series resistances leading to near-ideal capacitors. We then discuss the first experimental demonstration of a photon-plasmon-hybrid graphene-based electro-absorption modulator on silicon. The device shows a sub-1 V steep switching enabled by near-ideal electrostatics delivering a high 0.05 dB V-1 μm-1 performance requiring only 110 aJ/bit. Improving on this demonstration, we discuss a plasmonic slot-based graphene modulator design, where the polarization of the plasmonic mode aligns with graphene’s in-plane dimension; where a push-pull dual-gating scheme enables 2 dB V-1 μm-1 efficient modulation allowing the device to be just 770 nm short for 3 dB small signal modulation. Lastly, comparing the switching energy of transistors to modulators shows that modulators based on emerging materials and plasmonic-silicon hybrid integration perform on-par relative to their electronic counter parts. This in turn allows for a device-enabled two orders-of-magnitude improvement of electrical-optical co-integrated network-on-chips over electronic-only architectures. The latter opens technological opportunities in cognitive computing, dynamic data-driven applications systems, and optical analog computer engines including neuromorphic photonic computing.

Endothelial Activation by Platelets from Sickle Cell Anemia Patients

PubMed Central

Proença-Ferreira, Renata; Brugnerotto, Ana Flávia; Garrido, Vanessa Tonin; Dominical, Venina Marcela; Vital, Daiana Morelli; Ribeiro, Marilene de Fátima Reis; dos Santos, Melissa Ercolin; Traina, Fabíola; Olalla-Saad, Sara T.; Costa, Fernando Ferreira; Conran, Nicola

2014-01-01

Sickle cell anemia (SCA) is associated with a hypercoagulable state. Increased platelet activation is reported in SCA and SCA platelets may present augmented adhesion to the vascular endothelium, potentially contributing to the vaso-occlusive process. We sought to observe the effects of platelets (PLTs) from healthy control (CON) individuals and SCA individuals on endothelial activation, in vitro. Human umbilical vein endothelial cells (HUVEC) were cultured, in the presence, or not, of washed PLTs from CON or steady-state SCA individuals. Supernatants were reserved for cytokine quantification, and endothelial adhesion molecules (EAM) were analyzed by flow cytometry; gene expressions of ICAM1 and genes of the NF-κB pathway were analyzed by qPCR. SCA PLTs were found to be more inflammatory, displaying increased adhesive properties, an increased production of IL-1β and a tendency towards elevated expressions of P-selectin and activated αIIbβ3. Following culture in the presence of SCA PLTs, HUVEC presented significant augmentations in the expressions of the EAM, ICAM-1 and E-selectin, as well as increased IL-8 production and increased ICAM1 and NFKB1 (encodes p50 subunit of NF-κB) gene expressions. Interestingly, transwell inserts abolished the effects of SCA PLTs on EAM expression. Furthermore, an inhibitor of the NF-κB pathway, BAY 11-7082, also prevented the induction of EAM expression on the HUVEC surface by SCA PLTs. In conclusion, we find further evidence to indicate that platelets circulate in an activated state in sickle cell disease and are capable of stimulating endothelial cell activation. This effect appears to be mediated by direct contact, or even adhesion, between the platelets and endothelial cells and via NFκB-dependent signaling. As such, activated platelets in SCD may contribute to endothelial activation and, therefore, to the vaso-occlusive process. Results provide further evidence to support the use of anti-platelet approaches in association with other therapies for SCD. PMID:24551209

Protective effect of Azolla microphylla on biochemical, histopathological and molecular changes induced by isoproterenol in rats.

PubMed

Bhaskaran, Sreenath Kunnathupara; Kannappan, Poornima

2017-05-01

Azolla microphylla is an important fast-growing aquatic plant trusted for its agronomic, nutritious and therapeutic uses. The present work is undertaken to investigate the protective effect of the ethanolic extract of Azolla microphylla (EAM) against the Isoproterenol (ISO) induced cardiotoxicity in rats. Rats were pre-treated with EAM (250 and 500mg/kg b.w.) for 28 days along with ISO (85mg/kg; s.c.) on the 29th and 30th days. ISO-induced rats displayed significant diminution in cardiac antioxidant enzymes activities, increased lipid peroxidation and alteration in cardiac marker enzymes. The same group also displayed an increase in levels of serum lipid profiles and pro-inflammatory cytokines (IL-6 and IL-8) accompanied with a significant reduction in the anti-inflammatory cytokine levels (IL-10). Moreover, the histopathological investigations in the heart tissue of ISO-induced group exhibited myocardial necrosis and inflammation, which correlated with the increased immunoreactivity for Bax/iNOS, whereas an absence of reactivity for Bcl-2 proteins. However, in EAM pre-treated rats, the activities of antioxidant enzymes, cardiac marker enzymes, membrane-bound ATPases together with the levels of lipid profile, non-enzymatic antioxidants, pro and anti-inflammatory cytokines were maintained at normalcy that was further supported by improving histopathological changes and myocardial architecture. The IHC results of EAM pre-treated rats indicate up-regulated and down-regulated expressions of Bcl-2 and Bax/iNOS proteins, respectively. Thus, the present study reveals that A. microphylla alleviates myocardial damage in ISO-induced cardiac injury and demonstrates cardioprotective potential which could be attributed to its potent antioxidant and free radical scavenging activity. A possible mechanism for the protective effect is the elevated expression of endogenous antioxidant defense enzymes, anti-inflammatory cytokines, degraded lipid peroxidation products and improved energy metabolism of cardiac mitochondria, thus attenuating necrosis of the myocytes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Standardized unfold mapping: a technique to permit left atrial regional data display and analysis.

PubMed

Williams, Steven E; Tobon-Gomez, Catalina; Zuluaga, Maria A; Chubb, Henry; Butakoff, Constantine; Karim, Rashed; Ahmed, Elena; Camara, Oscar; Rhode, Kawal S

2017-10-01

Left atrial arrhythmia substrate assessment can involve multiple imaging and electrical modalities, but visual analysis of data on 3D surfaces is time-consuming and suffers from limited reproducibility. Unfold maps (e.g., the left ventricular bull's eye plot) allow 2D visualization, facilitate multimodal data representation, and provide a common reference space for inter-subject comparison. The aim of this work is to develop a method for automatic representation of multimodal information on a left atrial standardized unfold map (LA-SUM). The LA-SUM technique was developed and validated using 18 electroanatomic mapping (EAM) LA geometries before being applied to ten cardiac magnetic resonance/EAM paired geometries. The LA-SUM was defined as an unfold template of an average LA mesh, and registration of clinical data to this mesh facilitated creation of new LA-SUMs by surface parameterization. The LA-SUM represents 24 LA regions on a flattened surface. Intra-observer variability of LA-SUMs for both EAM and CMR datasets was minimal; root-mean square difference of 0.008 ± 0.010 and 0.007 ± 0.005 ms (local activation time maps), 0.068 ± 0.063 gs (force-time integral maps), and 0.031 ± 0.026 (CMR LGE signal intensity maps). Following validation, LA-SUMs were used for automatic quantification of post-ablation scar formation using CMR imaging, demonstrating a weak but significant relationship between ablation force-time integral and scar coverage (R 2  = 0.18, P < 0.0001). The proposed LA-SUM displays an integrated unfold map for multimodal information. The method is applicable to any LA surface, including those derived from imaging and EAM systems. The LA-SUM would facilitate standardization of future research studies involving segmental analysis of the LA.

Experimental demonstration of record high 19.125 Gb/s real-time end-to-end dual-band optical OFDM transmission over 25 km SMF in a simple EML-based IMDD system.

PubMed

Giddings, R P; Hugues-Salas, E; Tang, J M

2012-08-27

Record high 19.125 Gb/s real-time end-to-end dual-band optical OFDM (OOFDM) transmission is experimentally demonstrated, for the first time, in a simple electro-absorption modulated laser (EML)-based 25 km standard SMF system using intensity modulation and direct detection (IMDD). Adaptively modulated baseband (0-2GHz) and passband (6.125 ± 2GHz) OFDM RF sub-bands, supporting line rates of 10 Gb/s and 9.125 Gb/s respectively, are independently generated and detected with FPGA-based DSP clocked at only 100 MHz and DACs/ADCs operating at sampling speeds as low as 4GS/s. The two OFDM sub-bands are electrically frequency-division-multiplexed (FDM) for intensity modulation of a single optical carrier by an EML. To maximize and balance the signal transmission performance of each sub-band, on-line adaptive features and on-line performance monitoring is fully exploited to optimize key OOFDM transceiver and system parameters, which includes subcarrier characteristics within each individual OFDM sub-band, total and relative sub-band power as well as EML operating conditions. The achieved 19.125 Gb/s over 25 km SMF OOFDM transmission system has an optical power budget of 13.5 dB, and shows almost identical bit error rate (BER) performances for both the baseband and passband signals. In addition, experimental investigations also indicate that the maximum achievable transmission capacity of the present system is mainly determined by the EML frequency chirp-enhanced chromatic dispersion effect, and the passband BER performance is not affected by the two sub-band-induced intermixing effect, which, however, gives a 1.2dB optical power penalty to the baseband signal transmission.

Temperature and Pressure Dependences of the Elastic Properties of Tantalum Single Crystals Under <100> Tensile Loading: A Molecular Dynamics Study

NASA Astrophysics Data System (ADS)

Li, Wei-bing; Li, Kang; Fan, Kan-qi; Zhang, Da-xing; Wang, Wei-dong

2018-04-01

Atomistic simulations are capable of providing insights into physical mechanisms responsible for mechanical properties of the transition metal of Tantalum (Ta). By using molecular dynamics (MD) method, temperature and pressure dependences of the elastic properties of Ta single crystals are investigated through <100> tensile loading. First of all, a comparative study between two types of embedded-atom method (EAM) potentials is made in term of the elastic properties of Ta single crystals. The results show that Ravelo-EAM (Physical Review B, 2013, 88: 134101) potential behaves well at different hydrostatic pressures. Then, the MD simulation results based on the Ravelo-EAM potential show that Ta will experience a body-centered-cubic (BCC) to face-centered-cubic (FCC) phase transition before fracture under <100> tensile loading at 1 K temperature, and model size and strain rate have no obvious effects on tensile behaviors of Ta. Next, from the simulation results at the system temperature from 1 to 1500 K, it can be derived that the elastic modulus of E 100 linearly decrease with the increasing temperature, while the yielding stress decrease with conforming a quadratic polynomial formula. Finally, the pressure dependence of the elastic properties is performed from 0 to 140 GPa and the observations show that the elastic modulus increases with the increasing pressure overall.

Temperature and Pressure Dependences of the Elastic Properties of Tantalum Single Crystals Under <100> Tensile Loading: A Molecular Dynamics Study.

PubMed

Li, Wei-Bing; Li, Kang; Fan, Kang-Qi; Zhang, Da-Xing; Wang, Wei-Dong

2018-04-24

Atomistic simulations are capable of providing insights into physical mechanisms responsible for mechanical properties of the transition metal of Tantalum (Ta). By using molecular dynamics (MD) method, temperature and pressure dependences of the elastic properties of Ta single crystals are investigated through <100> tensile loading. First of all, a comparative study between two types of embedded-atom method (EAM) potentials is made in term of the elastic properties of Ta single crystals. The results show that Ravelo-EAM (Physical Review B, 2013, 88: 134101) potential behaves well at different hydrostatic pressures. Then, the MD simulation results based on the Ravelo-EAM potential show that Ta will experience a body-centered-cubic (BCC) to face-centered-cubic (FCC) phase transition before fracture under <100> tensile loading at 1 K temperature, and model size and strain rate have no obvious effects on tensile behaviors of Ta. Next, from the simulation results at the system temperature from 1 to 1500 K, it can be derived that the elastic modulus of E 100 linearly decrease with the increasing temperature, while the yielding stress decrease with conforming a quadratic polynomial formula. Finally, the pressure dependence of the elastic properties is performed from 0 to 140 GPa and the observations show that the elastic modulus increases with the increasing pressure overall.

In Situ Detection of Autoreactive CD4 T Cells in Brain and Heart Using Major Histocompatibility Complex Class II Dextramers

PubMed Central

Massilamany, Chandirasegaran; Gangaplara, Arunakumar; Jia, Ting; Elowsky, Christian; Li, Qingsheng; Zhou, You; Reddy, Jay

2014-01-01

This report demonstrates the use of major histocompatibility complex (MHC) class II dextramers for detection of autoreactive CD4 T cells in situ in myelin proteolipid protein (PLP) 139-151-induced experimental autoimmune encephalomyelitis (EAE) in SJL mice and cardiac myosin heavy chain-α (Myhc) 334-352-induced experimental autoimmune myocarditis (EAM) in A/J mice. Two sets of cocktails of dextramer reagents were used, where dextramers+ cells were analyzed by laser scanning confocal microscope (LSCM): EAE, IAs/PLP 139-151 dextramers (specific)/anti-CD4 and IAs/Theiler’s murine encephalomyelitis virus (TMEV) 70-86 dextramers (control)/anti-CD4; and EAM, IAk/Myhc 334-352 dextramers/anti-CD4 and IAk/bovine ribonuclease (RNase) 43-56 dextramers (control)/anti-CD4. LSCM analysis of brain sections obtained from EAE mice showed the presence of cells positive for CD4 and PLP 139-151 dextramers, but not TMEV 70-86 dextramers suggesting that the staining obtained with PLP 139-151 dextramers was specific. Likewise, heart sections prepared from EAM mice also revealed the presence of Myhc 334-352, but not RNase 43-56-dextramer+ cells as expected. Further, a comprehensive method has also been devised to quantitatively analyze the frequencies of antigen-specific CD4 T cells in the ‘Z’ serial images. PMID:25145797

Simulation of defects in fusion plasma first wall materials

NASA Astrophysics Data System (ADS)

T, Troev; N, Nankov; T, Yoshiie

2014-06-01

Numerical calculations of radiation damages in beryllium, alpha-iron and tungsten irradiated by fusion neutrons were performed using molecular dynamics (MD) simulations. The displacement cascades efficiency has been calculated using the Norgett-Robinson-Torrens (NRT) formula, the universal pair-potential of Ziegler-Biersack-Littmark (ZBL) and the EAM inter-atomic potential. The pair potential overestimates the defects production by a factor of 2. The ZBL pair potential results and the EAM are comparable at higher primary knock-on atom (PKA) energies (E > 100 keV). We found that the most common types of defects are single vacancies, di-vacancies, interstitials and small number of interstitial clusters. On the bases of calculated results, the behavior of vacancies, empty nano-voids and nano-voids with hydrogen and helium were discussed.

An exploration of the professional competencies required in engineering asset management

NASA Astrophysics Data System (ADS)

Bish, Adelle J.; Newton, Cameron J.; Browning, Vicky; O'Connor, Peter; Anibaldi, Renata

2014-07-01

Engineering asset management (EAM) is a rapidly growing and developing field. However, efforts to select and develop engineers in this area are complicated by our lack of understanding of the full range of competencies required to perform. This exploratory study sought to clarify and categorise the professional competencies required of individuals at different hierarchical levels within EAM. Data from 14 field interviews, 61 online surveys, and 10 expert panel interviews were used to develop an initial professional competency framework. Overall, nine competency clusters were identified. These clusters indicate that engineers working in this field need to be able to collaborate and influence others, complete objectives within organisational guidelines, and be able to manage themselves effectively. Limitations and potential uses of this framework in engineering education and research are discussed.

Application of the Ecosystem Assessment Model to Lake Norman: A cooling lake in North Carolina: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Porcella, D.B.; Bowie, G.L.; Campbell, C.L.

The Ecosystem Assessment Model (EAM) of the Cooling Lake Assessment Methodology was applied to the extensive ecological field data collected at Lake Norman, North Carolina by Duke Power Company to evaluate its capability to simulate lake ecosystems and the ecological effects of steam electric power plants. The EAM provided simulations over a five-year verification period that behaved as expected based on a one-year calibration. Major state variables of interest to utilities and regulatory agencies are: temperature, dissolved oxygen, and fish community variables. In qualitative terms, temperature simulation was very accurate, dissolved oxygen simulation was accurate, and fish prediction was reasonablymore » accurate. The need for more accurate fisheries data collected at monthly intervals and non-destructive sampling techniques was identified.« less

Tight-binding study of stacking fault energies and the Rice criterion of ductility in the fcc metals

NASA Astrophysics Data System (ADS)

Mehl, Michael J.; Papaconstantopoulos, Dimitrios A.; Kioussis, Nicholas; Herbranson, M.

2000-02-01

We have used the Naval Research Laboratory (NRL) tight-binding (TB) method to calculate the generalized stacking fault energy and the Rice ductility criterion in the fcc metals Al, Cu, Rh, Pd, Ag, Ir, Pt, Au, and Pb. The method works well for all classes of metals, i.e., simple metals, noble metals, and transition metals. We compared our results with full potential linear-muffin-tin orbital and embedded atom method (EAM) calculations, as well as experiment, and found good agreement. This is impressive, since the NRL-TB approach only fits to first-principles full-potential linearized augmented plane-wave equations of state and band structures for cubic systems. Comparable accuracy with EAM potentials can be achieved only by fitting to the stacking fault energy.

Optical Properties of Gallium Arsenide and Indium Gallium Arsenide Quantum Wells and Their Applications to Opto-Electronic Devices.

NASA Astrophysics Data System (ADS)

Huang, Daming

1990-01-01

In this thesis we investigate the optical properties of modulation doped GaAs/AlGaAs and strained-layer undoped InGaAs/GaAs multiple quantum well structures (MQWS). The phenomena studied are the effects of carrier, strain, and the electric field on the absorption of excitons. For GaAs/AlGaAs modulation doped MQWS, the quenching of excitons by free carriers has been demonstrated. The comparison of the experimental results with calculations which consider phase space filling, screening, and exchange interaction showed the phase space filling to be the dominant mechanism responsible for the change of oscillator strength and binding energy of excitons associated with partially filled subband. On the other hand, the screening and exchange interaction are equally important to excitons associated with empty subbands. For InGaAs/GaAs strained-layer MQWS, we have demonstrated that the band edges are dramatically modified by strain. We determined the band discontinuities at InGaAs/GaAs interfaces using optical absorption, and showed that in this structure the heavy holes are confined in InGaAs layers while the light holes are in GaAs layers, in contrast to GaAs/AlGaAs MQWS. We also explore applications of GaAs/AlGaAs and InGaAs/GaAs MQWS to opto-electronic devices. The principle of devices investigated is mainly based on the electric field effect on the excitonic absorption in MQWS (the quantum confined Stark effect). Two examples presented in this thesis are the strained-layer InGaAs/GaAs MQWS electroabsorption modulators grown on GaAs substrates and the GaAs/AlGaAs MQWS reflection modulators grown on Si substrates. The large modulation observed in the absorption coefficient by an electric field is expected to facilitate opto-electronic integration.

Quantitative Analysis of Electro-Anatomical Maps: Application to an Experimental Model of Left Bundle Branch Block/Cardiac Resynchronization Therapy

PubMed Central

Duchateau, Nicolas; Kostantyn Butakov, Constantine Butakoff; Andreu, David; Fernández-Armenta, Juan; Bijnens, Bart; Berruezo, Antonio; Sitges, Marta; Camara, Oscar

2017-01-01

Electro-anatomical maps (EAMs) are commonly acquired in clinical routine for guiding ablation therapies. They provide voltage and activation time information on a 3-D anatomical mesh representation, making them useful for analyzing the electrical activation patterns in specific pathologies. However, the variability between the different acquisitions and anatomies hampers the comparison between different maps. This paper presents two contributions for the analysis of electrical patterns in EAM data from biventricular surfaces of cardiac chambers. The first contribution is an integrated automatic 2-D disk representation (2-D bull’s eye plot) of the left ventricle (LV) and right ventricle (RV) obtained with a quasi-conformal mapping from the 3-D EAM meshes, that allows an analysis of cardiac resynchronization therapy (CRT) lead positioning, interpretation of global (total activation time), and local indices (local activation time (LAT), surrogates of conduction velocity, inter-ventricular, and transmural delays) that characterize changes in the electrical activation pattern. The second contribution is a set of indices derived from the electrical activation: speed maps, computed from LAT values, to study the electrical wave propagation, and histograms of isochrones to analyze regional electrical heterogeneities in the ventricles. We have applied the proposed methods to look for the underlying physiological mechanisms of left bundle branch block (LBBB) and CRT, with the goal of optimizing the therapy by improving CRT response. To better illustrate the benefits of the proposed tools, we created a set of synthetically generated and fully controlled activation patterns, where the proposed representation and indices were validated. Then, the proposed analysis tools are used to analyze EAM data from an experimental swine model of induced LBBB with an implanted CRT device. We have analyzed and compared the electrical activation patterns at baseline, LBBB, and CRT stages in four animals: two without any structural disease and two with an induced infarction. By relating the CRT lead location with electrical dyssynchrony, we evaluated current hypotheses about lead placement in CRT and showed that optimal pacing sites should target the RV lead close to the apex and the LV one distant from it. PMID:29164019

Improved prediction of heat of mixing and segregation in metallic alloys using tunable mixing rule for embedded atom method

NASA Astrophysics Data System (ADS)

Divi, Srikanth; Agrahari, Gargi; Ranjan Kadulkar, Sanket; Kumar, Sanjeet; Chatterjee, Abhijit

2017-12-01

Capturing segregation behavior in metal alloy nanoparticles accurately using computer simulations is contingent upon the availability of high-fidelity interatomic potentials. The embedded atom method (EAM) potential is a widely trusted interatomic potential form used with pure metals and their alloys. When limited experimental data is available, the A-B EAM cross-interaction potential for metal alloys AxB 1-x are often constructed from pure metal A and B potentials by employing a pre-defined ‘mixing rule’ without any adjustable parameters. While this approach is convenient, we show that for AuPt, NiPt, AgAu, AgPd, AuNi, NiPd, PtPd and AuPd such mixing rules may not even yield the correct alloy properties, e.g., heats of mixing, that are closely related to the segregation behavior. A general theoretical formulation based on scaling invariance arguments is introduced that addresses this issue by tuning the mixing rule to better describe alloy properties. Starting with an existing pure metal EAM potential that is used extensively in literature, we find that the mixing rule fitted to heats of mixing for metal solutions usually provides good estimates of segregation energies, lattice parameters and cohesive energy, as well as equilibrium distribution of metals within a nanoparticle using Monte Carlo simulations. While the tunable mixing rule generally performs better than non-adjustable mixing rules, the use of the tunable mixing rule may still require some caution. For e.g., in Pt-Ni system we find that the segregation behavior can deviate from the experimentally observed one at Ni-rich compositions. Despite this the overall results suggest that the same approach may be useful for developing improved cross-potentials with other existing pure metal EAM potentials as well. As a further test of our approach, mixing rule estimated from binary data is used to calculate heat of mixing in AuPdPt, AuNiPd, AuPtNi, AgAuPd and NiPtPd. Excellent agreement with experiments is observed for AuPdPt.

The feasibility and RE-AIM evaluation of the TAME health pilot study.

PubMed

Lewis, Zakkoyya H; Ottenbacher, Kenneth J; Fisher, Steve R; Jennings, Kristofer; Brown, Arleen F; Swartz, Maria C; Martinez, Eloisa; Lyons, Elizabeth J

2017-08-14

Conducting 5 A's counseling in clinic and utilizing technology-based resources are recommended to promote physical activity but little is known about how to implement such an intervention. This investigation aimed to determine the feasibility and acceptability, using the RE-AIM (Reach, Effectiveness, Adoption, Implementation, Maintenance) framework, of a pragmatic, primary care-based intervention that incorporated 5 A's counseling and self-control through an activity monitor. Primary care patients (n = 40) 55-74 years of age were recruited and randomized to receive a pedometer or an electronic activity monitor (EAM), Jawbone UP24, to monitor activity for 12 weeks. Participants were also invited to a focus group after completing the intervention. Stakeholders (n = 36) were recruited to provide feedback. The intervention recruitment rate was 24.7%. The attrition rate was 20% with a significantly higher rate for the pedometer group (p = 0.02). The EAM group increased their minutes of physical activity by 11.1 min/day while the pedometer maintained their activity (0.2 min/day), with no significant group difference. EAM participants liked using their monitor and would continue wearing it while the pedometer group was neutral to these statements (p < 0.05). Over the 12 weeks there were 490 comments and 1094 "likes" given to study peers in the corresponding application for the UP24 monitor. Some EAM participants enjoyed the social interaction feature while others were uncomfortable talking to strangers. Participants stated they would want counseling from a counselor and not their physician or a nurse. Other notable comments included incorporating multiple health behaviors, more in-person counseling with a counselor, and having a funding source for sustainability. Overall, the study was well-received but the results raise a number of considerations. Practitioners, counselors, and researchers should consider the following before implementing a similar intervention: 1) utilize PA counselors, 2) target multiple health behaviors, 3) form a social support group, 4) identify a funding source for sustainability, and 5) be mindful of concerns with technology. clinicaltrials.gov- NCT02554435 . Registered 24 August 2015.

Poetry and Poster Production.

ERIC Educational Resources Information Center

Shein, Dina

1993-01-01

Describes a school library media project for teaching poetry in which fifth-grade students write and illustrate a poem and produce a poster using the PosterPrinter machine. Suggestions for additional activities are included. (EAM)

Thermal transport in UO 2 with defects and fission products by molecular dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Xiang-Yang; Cooper, Michael William Donald; Mcclellan, Kenneth James

2015-10-14

The importance of the thermal transport in nuclear fuel has motivated a wide range of experimental and modelling studies. In this report, the reduction of thermal transport in UO 2 due to defects and fission products has been investigated using non-equilibrium MD simulations, with two sets of empirical potentials for studying the degregation of UO 2 thermal conductivity including a Buckingham type interatomic potential and a recently developed EAM type interatomic potential. Additional parameters for U 5+ and Zr 4+ in UO 2 have been developed for the EAM potential. The thermal conductivity results from MD simulations are then correctedmore » for the spin-phonon scattering through Callaway model formulations. To validate the modelling results, comparison was made with experimental measurements on single crystal hyper-stoichiometric UO 2+x samples.« less

Excitonic nature of optical transitions in electroabsorption spectra of perovskite solar cells

NASA Astrophysics Data System (ADS)

Ruf, Fabian; Magin, Alice; Schultes, Moritz; Ahlswede, Erik; Kalt, Heinz; Hetterich, Michael

2018-02-01

We investigate the electronic structure of solution-processed perovskite solar cells using temperature-dependent electroabsorption (EA) spectroscopy. Simultaneous measurements of absorption and electromodulated spectra of semitransparent methylammonium lead iodide solar cells facilitate a direct comparison of the specific features. The EA spectra can be transformed to peak-like line shapes utilizing an approach based on the Kramers-Kronig relations. The resulting peak positions correspond well to the discrete excitonic—rather than the continuum—contribution of the absorption spectra derived from generalized Elliott fits. This indicates the excitonic nature of the observed EA resonance and is found to be consistent over the whole temperature range investigated (from T = 10 K up to room temperature). To further confirm these findings, a line shape analysis of the measured EA spectra was performed. The best agreement was achieved using a first-derivative-like functional form which is expected for excitonic systems and supports the conclusion of an excitonic optical transition. Exciton binding energies EB are estimated for the orthorhombic and tetragonal phases as 26 meV and 19 meV, respectively. Nevertheless, power-conversion efficiencies η up to 13% (11.5% stabilized) demonstrate good charge-carrier separation in the devices due to sufficient thermal dissociation and Sommerfeld-enhanced absorption.

Extending the accuracy of the SNAP interatomic potential form

NASA Astrophysics Data System (ADS)

Wood, Mitchell A.; Thompson, Aidan P.

2018-06-01

The Spectral Neighbor Analysis Potential (SNAP) is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. An extension of the SNAP form is proposed that includes quadratic terms in the bispectrum components. The extension is shown to provide a large increase in accuracy relative to the linear form, while incurring only a modest increase in computational cost. The mathematical structure of the quadratic SNAP form is similar to the embedded atom method (EAM), with the SNAP bispectrum components serving as counterparts to the two-body density functions in EAM. The effectiveness of the new form is demonstrated using an extensive set of training data for tantalum structures. Similar to artificial neural network potentials, the quadratic SNAP form requires substantially more training data in order to prevent overfitting. The quality of this new potential form is measured through a robust cross-validation analysis.

Hybrid Silicon Photonic Integration using Quantum Well Intermixing

NASA Astrophysics Data System (ADS)

Jain, Siddharth R.

With the push for faster data transfer across all domains of telecommunication, optical interconnects are transitioning into shorter range applications such as in data centers and personal computing. Silicon photonics, with its economic advantages of leveraging well-established silicon manufacturing facilities, is considered the most promising approach to further scale down the cost and size of optical interconnects for chip-to-chip communication. Intrinsic properties of silicon however limit its ability to generate and modulate light, both of which are key to realizing on-chip optical data transfer. The hybrid silicon approach directly addresses this problem by using molecularly bonded III-V epitaxial layers on silicon for optical gain and absorption. This technology includes direct transfer of III-V wafer to a pre-patterned silicon-on-insulator wafer. Several discrete devices for light generation, modulation, amplification and detection have already been demonstrated on this platform. As in the case of electronics, multiple photonic elements can be integrated on a single chip to improve performance and functionality. However, scalable photonic integration requires the ability to control the bandgap for individual devices along with design changes to simplify fabrication. In the research presented here, quantum well intermixing is used as a technique to define multiple bandgaps for integration on the hybrid silicon platform. Implantation enhanced disordering is used to generate four bandgaps spread over 120+ nm. By combining these selectively intermixed III-V layers with pre-defined gratings and waveguides on silicon, we fabricate distributed feedback, distributed Bragg reflector, Fabry-Perot and mode-locked lasers along with photodetectors, electro-absorption modulators and other test structures, all on a single chip. We demonstrate a broadband laser source with continuous-wave operational lasers over a 200 nm bandwidth. Some of these lasers are integrated with modulators with a 3-dB bandwidth above 25 GHz, thus demonstrating coarse wavelength division multiplexing transmitter on silicon.

Equine atypical myopathy caused by hypoglycin A intoxication associated with ingestion of sycamore maple tree seeds.

PubMed

Żuraw, A; Dietert, K; Kühnel, S; Sander, J; Klopfleisch, R

2016-07-01

Evidence suggest there is a link between equine atypical myopathy (EAM) and ingestion of sycamore maple tree seeds. To further evaluate the hypothesis that the ingestion of hypoglycin A (HGA) containing sycamore maple tree seeds causes acquired multiple acyl-CoA dehydrogenase deficiency and might be associated with the clinical and pathological signs of EAM. Case report. Necropsy and histopathology, using hematoxylin and eosin and Sudan III stains, were performed on a 2.5-year-old mare that died following the development of clinical signs of progressive muscle stiffness and recumbency. Prior to death, the animal ingested sycamore maple tree seeds (Acer pseudoplatanus). Detection of metabolites in blood and urine obtained post mortem was performed by rapid ultra-performance liquid chromatography-tandem mass spectrometry. Data from this case were compared with 3 geldings with no clinical history of myopathy. Macroscopic examination revealed fragments of maple tree seeds in the stomach and severe myopathy of several muscle groups including Mm. intercostales, deltoidei and trapezii. Histologically, the affected muscles showed severe, acute rhabdomyolysis with extensive accumulation of finely dispersed fat droplets in the cytoplasm of degenerated skeletal muscle cells not present in controls. Urine and serum concentrations of several acyl carnitines and acyl glycines were increased, and both contained metabolites of HGA, a toxic amino acid present in sycamore maple tree seeds. The study supports the hypothesis that ingestion of HGA-containing maple tree seeds may cause EAM due to acquired multiple acyl-CoA dehydrogenase deficiency. © 2015 EVJ Ltd.

The 1993 AIA/ALA Building Award Recipients.

ERIC Educational Resources Information Center

Muller, Karen

1993-01-01

Describes the eight library buildings that won the 1993 Awards of Excellence for Library Architecture from the American Institute of Architects (AIA) and the American Library Association (ALA) including one adaptive reuse, four expansions, two new buildings, and one temporary building. (EAM)

Easy Online Access to Helpful Internet Guides.

ERIC Educational Resources Information Center

Tuss, Joan

1993-01-01

Lists recommended guides to the Internet that are available electronically. Basic commands needed to use anonymous ftp (file transfer protocol) are explained. An annotation and command formats to access, scan, retrieve, and exit each file are included for 11 titles. (EAM)

Multimedia: The Future of Information Delivery to Homes and Businesses.

ERIC Educational Resources Information Center

Katz, Matthew

1993-01-01

Provides an overview of developments in bringing affordable interactive multimedia services to homes and businesses. Viewpoints and efforts of leaders in the movement toward an electronic superhighway are described, including cable companies, telephone companies, entertainment, and publishing industries. (EAM)

Copyright Catechism.

ERIC Educational Resources Information Center

Burke, Edmund B.

1993-01-01

Provides a basic introduction to copyright through a question-and-answer format. Topics covered include definition of copyright, copyright notices and registration, rights to owners, duration, software, civil and criminal penalties, the work-made-for-hire doctrine, fair use, transfer, international scope, licenses, and student materials. (EAM)

Nanothermodynamics of iron clusters: Small clusters, icosahedral and fcc-cuboctahedral structures

NASA Astrophysics Data System (ADS)

Angelié, C.; Soudan, J.-M.

2017-05-01

The study of the thermodynamics and structures of iron clusters has been carried on, focusing on small clusters and initial icosahedral and fcc-cuboctahedral structures. Two combined tools are used. First, energy intervals are explored by the Monte Carlo algorithm, called σ-mapping, detailed in the work of Soudan et al. [J. Chem. Phys. 135, 144109 (2011), Paper I]. In its flat histogram version, it provides the classical density of states, gp(Ep), in terms of the potential energy of the system. Second, the iron system is described by a potential which is called "corrected EAM" (cEAM), explained in the work of Basire et al. [J. Chem. Phys. 141, 104304 (2014), Paper II]. Small clusters from 3 to 12 atoms in their ground state have been compared first with published Density Functional Theory (DFT) calculations, giving a complete agreement of geometries. The series of 13, 55, 147, and 309 atom icosahedrons is shown to be the most stable form for the cEAM potential. However, the 147 atom cluster has a special behaviour, since decreasing the energy from the liquid zone leads to the irreversible trapping of the cluster in a reproducible amorphous state, 7.38 eV higher in energy than the icosahedron. This behaviour is not observed at the higher size of 309 atoms. The heat capacity of the 55, 147, and 309 atom clusters revealed a pronounced peak in the solid zone, related to a solid-solid transition, prior to the melting peak. The corresponding series of 13, 55, and 147 atom cuboctahedrons has been compared, underscoring the unstability towards the icosahedral structure. This unstability occurs clearly in several steps for the 147 atom cluster, with a sudden transformation at a transition state. This illustrates the concerted icosahedron-cuboctahedron transformation of Buckminster Fuller-Mackay, which is calculated for the cEAM potential. Two other clusters of initial fcc structures with 24 and 38 atoms have been studied, as well as a 302 atom cluster. Each one relaxes towards a more stable structure without regularity. The 38 atom cluster exhibits a nearly glassy relaxation, through a cascade of six metastable states of long life. This behaviour, as that of the 147 atom cluster towards the amorphous state, shows that difficulties to reach ergodicity in the lower half of the solid zone are related to particular features of the potential energy landscape, and not necessarily to a too large size of the system. Comparisons of the cEAM iron system with published results about Lennard-Jones systems and DFT calculations are made. The results of the previous clusters have been combined with that of Paper II to plot the cohesive energy Ec and the melting temperature Tm in terms of the cluster atom number Nat. The Nat -1 /3 linear dependence of the melting temperature (Pawlow law) is observed again for Nat > 150. In contrast, for Nat < 150, the curve diverges strongly from the Pawlow law, giving it an overall V-shape, with a linear increase of Tm when Nat goes from 55 to 13 atoms. Surprisingly, the 38 atom cluster is anomalously below the overall curve.

Information Transfer and the Adoption of Agricultural Innovations.

ERIC Educational Resources Information Center

Longo, Rose Mary Juliano

1990-01-01

Data collected in the Federal District of Brazil were analyzed in terms of information transfer through mass media and interpersonal communication and how they influence farmers in the Federal District of Brazil in their decisions to adopt agricultural innovations. (42 references) (EAM)

A Mandate for Change in the Library Environment.

ERIC Educational Resources Information Center

Silberman, Richard M.

1993-01-01

The problem of indoor air quality and sick-building syndrome in libraries is explained in terms of human health and comfort and the preservation of books and manuscripts. Ventilation and indoor pollutants are discussed, and a proactive strategy of prevention is recommended. (EAM)

Multibillion-atom Molecular Dynamics Simulations of Plasticity, Spall, and Ejecta

NASA Astrophysics Data System (ADS)

Germann, Timothy C.

2007-06-01

Modern supercomputing platforms, such as the IBM BlueGene/L at Lawrence Livermore National Laboratory and the Roadrunner hybrid supercomputer being built at Los Alamos National Laboratory, are enabling large-scale classical molecular dynamics simulations of phenomena that were unthinkable just a few years ago. Using either the embedded atom method (EAM) description of simple (close-packed) metals, or modified EAM (MEAM) models of more complex solids and alloys with mixed covalent and metallic character, simulations containing billions to trillions of atoms are now practical, reaching volumes in excess of a cubic micron. In order to obtain any new physical insights, however, it is equally important that the analysis of such systems be tractable. This is in fact possible, in large part due to our highly efficient parallel visualization code, which enables the rendering of atomic spheres, Eulerian cells, and other geometric objects in a matter of minutes, even for tens of thousands of processors and billions of atoms. After briefly describing the BlueGene/L and Roadrunner architectures, and the code optimization strategies that were employed, results obtained thus far on BlueGene/L will be reviewed, including: (1) shock compression and release of a defective EAM Cu sample, illustrating the plastic deformation accompanying void collapse as well as the subsequent void growth and linkup upon release; (2) solid-solid martensitic phase transition in shock-compressed MEAM Ga; and (3) Rayleigh-Taylor fluid instability modeled using large-scale direct simulation Monte Carlo (DSMC) simulations. I will also describe our initial experiences utilizing Cell Broadband Engine processors (developed for the Sony PlayStation 3), and planned simulation studies of ejecta and spall failure in polycrystalline metals that will be carried out when the full Petaflop Opteron/Cell Roadrunner supercomputer is assembled in mid-2008.

Autobiographical Memory Deficits in Alcohol-Dependent Patients with Short- and Long-Term Abstinence.

PubMed

Nandrino, Jean-Louis; El Haj, Mohamad; Torre, Julie; Naye, Delphine; Douchet, Helyette; Danel, Thierry; Cottençin, Oliver

2016-04-01

Autobiographical memory (AM) enables the storage and retrieval of life experiences that allow individuals to build their sense of identity. Several AM impairments have been described in patients with alcohol abuse disorders without assessing whether such deficits can be recovered. This cross-sectional study aimed to identify whether the semantic (SAM) and episodic (EAM) dimensions of AM are affected in individuals with alcohol dependence after short-term abstinence (STA) or long-term abstinence (LTA). A second aim of this study was to examine the factors that could disrupt the efficiency of semantic and episodic AM (the impact of depression severity, cognitive functions, recent or early traumatic events, and drinking history variables). After clinical and cognitive evaluations (alcohol consumption, depression, anxiety, IQ, memory performance), AM was assessed with the Autobiographical Memory Interview in patients with recent (between 4 and 6 weeks) and longer (at least 6 months) abstinence. Participants were asked to retrieve the number and nature of traumatic or painful life experiences in recent or early life periods (using the Childhood Traumatic Events Scale). The 2 abstinent groups had lower global EAM and SAM scores than the control group. These scores were comparable for both abstinent groups. For childhood events, no significant differences were observed in SAM for both groups compared with control participants. For early adulthood and recent events, both STA and LTA groups had lower scores on both SAM and EAM. Moreover, there was a negative correlation between the length of substance consumption and SAM scores. This study highlighted a specific AM disorder in both episodic and semantic dimensions. These deficits remained after 6 months of abstinence. This AM impairment may be explained by compromised encoding and consolidation of memories during bouts of drinking. Copyright © 2016 by the Research Society on Alcoholism.

Outbreak of cholera in the East Akim Municipality of Ghana following unhygienic practices by small-scale gold miners, November 2010.

PubMed

Opare, Jkl; Ohuabunwo, C; Afari, E; Wurapa, F; Sackey, So; Der, J; Afakye, K; Odei, E

2012-09-01

In October 2010 an outbreak of cholera began among a group of small-scale gold miners in the East-Akim Municipality (EAM), Eastern Region. We investigated to verify the diagnosis, identify risk factors and recommend control measures. We conducted a descriptive investigation, active case-search and an unmatched case-control study. A cholera case-patient was a person with acute watery diarrhoea, with or without vomiting in EAM from 1st October to 20(th) November, 2010. Stool from case-patients and water samples were taken for laboratory diagnosis. We performed univariate and bivariate analysis using epi-info version 3.3. Of 136 case-patients, 77 (56.6%) were males, of which 40% were miners or from miners households. Index case, a 20 yr-old male miner from Apapam village reported on October 13(th), and case-patients peaked (18.4%) 20 days later. Attack rate was 2/1000 population with no fatality. Ages ranged from 1-84 years; mean of 34±18 yrs. Age-group 20-29 yrs was mostly affected (30.1%) with Apapam village having most case-patients (19.9%). Vibrio cholera serotype ogawa was isolated from stool samples. The main water source, Birim river was polluted by small-scale miners through defecation, post-defecation baths and sand-washings. Compared to controls, case-patients were more likely to have drunk from Birim-River [OR= 6.99, 95% CI: 2.75-18]. Vibrio cholera serotype ogawa caused the EAM cholera-outbreak affecting many young adult-males. Drinking water from contaminated community-wide -River was the major risk factors. Boiling or chlorination of water was initiated based on our recommendations and this controlled the outbreak.

First In Vivo Use of a Capacitive Micromachined Ultrasound Transducer Array–Based Imaging and Ablation Catheter

PubMed Central

Stephens, Douglas N.; Truong, Uyen T.; Nikoozadeh, Amin; Oralkan, Ömer; Seo, Chi Hyung; Cannata, Jonathan; Dentinger, Aaron; Thomenius, Kai; de la Rama, Alan; Nguyen, Tho; Lin, Feng; Khuri-Yakub, Pierre; Mahajan, Aman; Shivkumar, Kalyanam; O’Donnell, Matt; Sahn, David J.

2012-01-01

Objectives The primary objective was to test in vivo for the first time the general operation of a new multifunctional intracardiac echocardiography (ICE) catheter constructed with a microlinear capacitive micromachined ultrasound transducer (ML-CMUT) imaging array. Secondarily, we examined the compatibility of this catheter with electroanatomic mapping (EAM) guidance and also as a radiofrequency ablation (RFA) catheter. Preliminary thermal strain imaging (TSI)-derived temperature data were obtained from within the endocardium simultaneously during RFA to show the feasibility of direct ablation guidance procedures. Methods The new 9F forward-looking ICE catheter was constructed with 3 complementary technologies: a CMUT imaging array with a custom electronic array buffer, catheter surface electrodes for EAM guidance, and a special ablation tip, that permits simultaneous TSI and RFA. In vivo imaging studies of 5 anesthetized porcine models with 5 CMUT catheters were performed. Results The ML-CMUT ICE catheter provided high-resolution real-time wideband 2-dimensional (2D) images at greater than 8 MHz and is capable of both RFA and EAM guidance. Although the 24-element array aperture dimension is only 1.5 mm, the imaging depth of penetration is greater than 30 mm. The specially designed ultrasound-compatible metalized plastic tip allowed simultaneous imaging during ablation and direct acquisition of TSI data for tissue ablation temperatures. Postprocessing analysis showed a first-order correlation between TSI and temperature, permitting early development temperature-time relationships at specific myocardial ablation sites. Conclusions Multifunctional forward-looking ML-CMUT ICE catheters, with simultaneous intracardiac guidance, ultrasound imaging, and RFA, may offer a new means to improve interventional ablation procedures. PMID:22298868

Towards optical spectroscopic anatomical mapping (OSAM) for lesion validation in cardiac tissue (Conference Presentation)

NASA Astrophysics Data System (ADS)

Singh-Moon, Rajinder P.; Zaryab, Mohammad; Hendon, Christine P.

2017-02-01

Electroanatomical mapping (EAM) is an invaluable tool for guiding cardiac radiofrequency ablation (RFA) therapy. The principle roles of EAM is the identification of candidate ablation sites by detecting regions of abnormal electrogram activity and lesion validation subsequent to RF energy delivery. However, incomplete lesions may present interim electrical inactivity similar to effective treatment in the acute setting, despite efforts to reveal them with pacing or drugs, such as adenosine. Studies report that the misidentification and recovery of such lesions is a leading cause of arrhythmia recurrence and repeat procedures. In previous work, we demonstrated spectroscopic characterization of cardiac tissues using a fiber optic-integrated RF ablation catheter. In this work, we introduce OSAM (optical spectroscopic anatomical mapping), the application of this spectroscopic technique to obtain 2-dimensional biodistribution maps. We demonstrate its diagnostic potential as an auxiliary method for lesion validation in treated swine preparations. Endocardial lesion sets were created on fresh swine cardiac samples using a commercial RFA system. An optically-integrated catheter console fabricated in-house was used for measurement of tissue optical spectra between 600-1000nm. Three dimensional, Spatio-spectral datasets were generated by raster scanning of the optical catheter across the treated sample surface in the presence of whole blood. Tissue optical parameters were recovered at each spatial position using an inverse Monte Carlo method. OSAM biodistribution maps showed stark correspondence with gross examination of tetrazolium chloride stained tissue specimens. Specifically, we demonstrate the ability of OSAM to readily distinguish between shallow and deeper lesions, a limitation faced by current EAM techniques. These results showcase the OSAMs potential for lesion validation strategies for the treatment of cardiac arrhythmias.

Targeted Therapy for Acute Autoimmune Myocarditis with Nano-Sized Liposomal FK506 in Rats.

PubMed

Okuda, Keiji; Fu, Hai Ying; Matsuzaki, Takashi; Araki, Ryo; Tsuchida, Shota; Thanikachalam, Punniyakoti V; Fukuta, Tatsuya; Asai, Tomohiro; Yamato, Masaki; Sanada, Shoji; Asanuma, Hiroshi; Asano, Yoshihiro; Asakura, Masanori; Hanawa, Haruo; Hao, Hiroyuki; Oku, Naoto; Takashima, Seiji; Kitakaze, Masafumi; Sakata, Yasushi; Minamino, Tetsuo

2016-01-01

Immunosuppressive agents are used for the treatment of immune-mediated myocarditis; however, the need to develop a more effective therapeutic approach remains. Nano-sized liposomes may accumulate in and selectively deliver drugs to an inflammatory lesion with enhanced vascular permeability. The aims of this study were to investigate the distribution of liposomal FK506, an immunosuppressive drug encapsulated within liposomes, and the drug's effects on cardiac function in a rat experimental autoimmune myocarditis (EAM) model. We prepared polyethylene glycol-modified liposomal FK506 (mean diameter: 109.5 ± 4.4 nm). We induced EAM by immunization with porcine myosin and assessed the tissue distribution of the nano-sized beads and liposomal FK506 in this model. After liposomal or free FK506 was administered on days 14 and 17 after immunization, the cytokine expression in the rat hearts along with the histological findings and hemodynamic parameters were determined on day 21. Ex vivo fluorescent imaging revealed that intravenously administered fluorescent-labeled nano-sized beads had accumulated in myocarditic but not normal hearts on day 14 after immunization and thereafter. Compared to the administration of free FK506, FK506 levels were increased in both the plasma and hearts of EAM rats when liposomal FK506 was administered. The administration of liposomal FK506 markedly suppressed the expression of cytokines, such as interferon-γ and tumor necrosis factor-α, and reduced inflammation and fibrosis in the myocardium on day 21 compared to free FK506. The administration of liposomal FK506 also markedly ameliorated cardiac dysfunction on day 21 compared to free FK506. Nano-sized liposomes may be a promising drug delivery system for targeting myocarditic hearts with cardioprotective agents.

Left ventricular lead placement in the latest activated region guided by coronary venous electroanatomic mapping.

PubMed

Rad, Masih Mafi; Blaauw, Yuri; Dinh, Trang; Pison, Laurent; Crijns, Harry J; Prinzen, Frits W; Vernooy, Kevin

2015-01-01

Left ventricular (LV) lead placement in the latest activated region is an important determinant of response to cardiac resynchronization therapy (CRT). We investigated the feasibility of coronary venous electroanatomic mapping (EAM) to guide LV lead placement to the latest activated region. Twenty-five consecutive CRT candidates with left bundle-branch block underwent intra-procedural coronary venous EAM using EnSite NavX. A guidewire was used to map the coronary veins during intrinsic activation, and to test for phrenic nerve stimulation (PNS). The latest activated region, defined as the region with an electrical delay >75% of total QRS duration, was located anterolaterally in 18 (basal, n = 10; mid, n = 8) and inferolaterally in 6 (basal, n = 3; mid, n = 3). In one patient, identification of the latest activated region was impeded by limited coronary venous anatomy. In patients with >1 target vein (n = 12), the anatomically targeted inferolateral vein was rarely the vein with maximal electrical delay (n = 3). A concordant LV lead position was achieved in 18 of 25 patients. In six patients, this was hampered by PNS (n = 4), lead instability (n = 1), and coronary vein stenosis (n = 1). Coronary venous EAM can be used intraprocedurally to guide LV lead placement to the latest activated region free of PNS. This approach especially contributes to optimization of LV lead electrical delay in patients with multiple target veins. Conventional anatomical LV lead placement strategy does not target the vein with maximal electrical delay in many of these patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.

Testing Activity Monitors’ Effect on Health: Study Protocol for a Randomized Controlled Trial Among Older Primary Care Patients

PubMed Central

Ottenbacher, Kenneth J; Fisher, Steve R; Jennings, Kristofer; Brown, Arleen F; Swartz, Maria C; Lyons, Elizabeth J

2016-01-01

Background Cardiovascular disease is the leading cause of mortality in the United States. Maintaining healthy levels of physical activity is critical to cardiovascular health, but many older adults are inactive. There is a growing body of evidence linking low motivation and inactivity. Standard behavioral counseling techniques used within the primary care setting strive to increase motivation, but often do not emphasize the key component of self-control. The addition of electronic activity monitors (EAMs) to counseling protocols may provide more effective behavior change and increase overall motivation for exercise through interactive self-monitoring, feedback, and social support from other users. Objective The objective of the study is to conduct a three month intervention trial that will test the feasibility of adding an EAM system to brief counseling within a primary care setting. Participants (n=40) will be randomized to receive evidence-based brief counseling plus either an EAM or a pedometer. Methods Throughout the intervention, we will test its feasibility and acceptability, the change in primary outcomes (cardiovascular risk and physical activity), and the change in secondary outcomes (adherence, weight and body composition, health status, motivation, physical function, psychological feelings, and self-regulation). Upon completion of the intervention, we will also conduct focus groups with the participants and with primary care stakeholders. Results The study started recruitment in October 2015 and is scheduled to be completed by October 2016. Conclusions This project will lay the groundwork and establish the infrastructure for intervention refinement and ultimately translation within the primary care setting in order to prevent cardiovascular disease on a population level. Trial Registration ClinicalTrails.gov NCT02554435; https://clinicaltrials.gov/ct2/show/NCT02554435 (Archived by WebCite at http://www.webcitation/6fUlW5tdT) PMID:27129602

Cold in-place recycling and full-depth recycling with asphalt products (CIR&FDRwAP).

DOT National Transportation Integrated Search

2009-03-01

In the 60s, 70s, and 80s, many Illinois local road agencies successfully used conventional asphalt : emulsions for In-Place Recycling to produce Emulsion-Aggregate-Mixtures (EAMs). In more recent years, these : emulsions have not been ...

The Basic Economics of CD-ROM Pricing.

ERIC Educational Resources Information Center

Erkkila, John E.

1991-01-01

This explanation of how the basic economic model of pricing applies to the CD-ROM industry considers the supply and demand sides of the market and compares three distinct pricing strategies: (1) pricing to maximize profits; (2) average cost pricing; and (3) marginal cost pricing. (EAM)

The Global Systems Analysis and Simulation (GLOSAS) Project, and the Global Lecture Hall (GLH) Operating at the Orlando ICEM Conference.

ERIC Educational Resources Information Center

Bell, John

1993-01-01

Introduces two articles which describe an interactive video conference between North and South America, the Caribbean, Europe, and Scandinavia as part of the International Council for Educational Media (ICEM) 1992 conference. (EAM)

Effect of vacancy defects on generalized stacking fault energy of fcc metals.

PubMed

Asadi, Ebrahim; Zaeem, Mohsen Asle; Moitra, Amitava; Tschopp, Mark A

2014-03-19

Molecular dynamics (MD) and density functional theory (DFT) studies were performed to investigate the influence of vacancy defects on generalized stacking fault (GSF) energy of fcc metals. MEAM and EAM potentials were used for MD simulations, and DFT calculations were performed to test the accuracy of different common parameter sets for MEAM and EAM potentials in predicting GSF with different fractions of vacancy defects. Vacancy defects were placed at the stacking fault plane or at nearby atomic layers. The effect of vacancy defects at the stacking fault plane and the plane directly underneath of it was dominant compared to the effect of vacancies at other adjacent planes. The effects of vacancy fraction, the distance between vacancies, and lateral relaxation of atoms on the GSF curves with vacancy defects were investigated. A very similar variation of normalized SFEs with respect to vacancy fractions were observed for Ni and Cu. MEAM potentials qualitatively captured the effect of vacancies on GSF.

Electroactive microorganisms in bulk solution contribute significantly to methane production in bioelectrochemical anaerobic reactor.

PubMed

Feng, Qing; Song, Young-Chae; Ahn, Yongtae

2018-07-01

The role of anaerobic microorganisms suspended in the bulk solution on methane production was investigated in a bioelectrochemical anaerobic reactor with the electrode polarized at 0.5 V. The electron transfer from substrate to methane and hydrogen were 25% and 7.5%, respectively, in the absence of the anaerobic microorganisms in the bulk solution. As the anaerobic microorganisms increased to 4400 mg/L, the electrons transferred to methane increased to 83.3% but decreased to 0.3% in hydrogen. The electroactive microorganisms (EAM), including exoelectrogens and electrotrophs, enriched in the bulk solution that confirmed by the redox peaks in the cyclic voltammogram was proportional to the anaerobic microorganism. The methane yield based on COD removal was dependent on the anaerobic microorganisms in the bulk solution rather than on the bioelectrode surface. The EAM suspended in the bulk solution are enriched by the polarized electrode, and significantly improve methane production in bioelectrochemical anaerobic reactor. Copyright © 2018 Elsevier Ltd. All rights reserved.

Extending the accuracy of the SNAP interatomic potential form

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, Mitchell A.; Thompson, Aidan P.

The Spectral Neighbor Analysis Potential (SNAP) is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. An extension of the SNAP form is proposed that includes quadratic terms in the bispectrum components. The extension is shown to provide a large increase in accuracy relative to the linear form, while incurring only a modest increase in computational cost. The mathematical structure of the quadratic SNAP form is similar to the embedded atom method (EAM), with the SNAP bispectrum components serving as counterparts to the two-body density functionsmore » in EAM. It is also argued that the quadratic SNAP form is a special case of an artificial neural network (ANN). The effectiveness of the new form is demonstrated using an extensive set of training data for tantalum structures. Similarly to ANN potentials, the quadratic SNAP form requires substantially more training data in order to prevent overfitting, as measured by cross-validation analysis.« less

Structural and dynamical properties of liquid Al-Au alloys

NASA Astrophysics Data System (ADS)

Peng, H. L.; Voigtmann, Th.; Kolland, G.; Kobatake, H.; Brillo, J.

2015-11-01

We investigate temperature- and composition-dependent structural and dynamical properties of Al-Au melts. Experiments are performed to obtain accurate density and viscosity data. The system shows a strong negative excess volume, similar to other Al-based binary alloys. We develop a molecular-dynamics (MD) model of the melt based on the embedded-atom method (EAM), gauged against the available experimental liquid-state data. A rescaling of previous EAM potentials for solid-state Au and Al improves the quantitative agreement with experimental data in the melt. In the MD simulation, the admixture of Au to Al can be interpreted as causing a local compression of the less dense Al system, driven by less soft Au-Au interactions. This local compression provides a microscopic mechanism explaining the strong negative excess volume of the melt. We further discuss the concentration dependence of self- and interdiffusion and viscosity in the MD model. Al atoms are more mobile than Au, and their increased mobility is linked to a lower viscosity of the melt.

Extending the accuracy of the SNAP interatomic potential form

DOE PAGES

Wood, Mitchell A.; Thompson, Aidan P.

2018-03-28

The Spectral Neighbor Analysis Potential (SNAP) is a classical interatomic potential that expresses the energy of each atom as a linear function of selected bispectrum components of the neighbor atoms. An extension of the SNAP form is proposed that includes quadratic terms in the bispectrum components. The extension is shown to provide a large increase in accuracy relative to the linear form, while incurring only a modest increase in computational cost. The mathematical structure of the quadratic SNAP form is similar to the embedded atom method (EAM), with the SNAP bispectrum components serving as counterparts to the two-body density functionsmore » in EAM. It is also argued that the quadratic SNAP form is a special case of an artificial neural network (ANN). The effectiveness of the new form is demonstrated using an extensive set of training data for tantalum structures. Similarly to ANN potentials, the quadratic SNAP form requires substantially more training data in order to prevent overfitting, as measured by cross-validation analysis.« less

Managing emergencies and abnormal situations in air traffic control (part II): teamwork strategies.

PubMed

Malakis, Stathis; Kontogiannis, Tom; Kirwan, Barry

2010-07-01

Team performance has been studied in many safety-critical organizations including aviation, nuclear power plant, offshore oil platforms and health organizations. This study looks into teamwork strategies that air traffic controllers employ to manage emergencies and abnormal situations. Two field studies were carried out in the form of observations of simulator training in emergency and unusual scenarios of novices and experienced controllers. Teamwork strategies covered aspects of team orientation and coordination, information exchange, change management and error handling. Several performance metrics were used to rate the efficiency of teamwork and test the construct validity of a prototype model of teamwork. This is a companion study to an earlier investigation of taskwork strategies in the same field (part I) and contributes to the development of a generic model for Taskwork and Teamwork strategies in Emergencies in Air traffic Management (T(2)EAM). Suggestions are made on how to use T(2)EAM to develop training programs, assess team performance and improve mishap investigations. Copyright 2010 Elsevier Ltd. All rights reserved.

Implementation of metal-friendly EAM/FS-type semi-empirical potentials in HOOMD-blue: A GPU-accelerated molecular dynamics software

NASA Astrophysics Data System (ADS)

Yang, Lin; Zhang, Feng; Wang, Cai-Zhuang; Ho, Kai-Ming; Travesset, Alex

2018-04-01

We present an implementation of EAM and FS interatomic potentials, which are widely used in simulating metallic systems, in HOOMD-blue, a software designed to perform classical molecular dynamics simulations using GPU accelerations. We first discuss the details of our implementation and then report extensive benchmark tests. We demonstrate that single-precision floating point operations efficiently implemented on GPUs can produce sufficient accuracy when compared against double-precision codes, as demonstrated in test simulations of calculations of the glass-transition temperature of Cu64.5Zr35.5, and pair correlation function g (r) of liquid Ni3Al. Our code scales well with the size of the simulating system on NVIDIA Tesla M40 and P100 GPUs. Compared with another popular software LAMMPS running on 32 cores of AMD Opteron 6220 processors, the GPU/CPU performance ratio can reach as high as 4.6. The source code can be accessed through the HOOMD-blue web page for free by any interested user.

Molecular dynamics simulation of metallic impurity diffusion in liquid lead-bismuth eutectic (LBE)

NASA Astrophysics Data System (ADS)

Gao, Yun; Takahashi, Minoru; Cavallotti, Carlo; Raos, Guido

2018-04-01

Corrosion of stainless steels by lead-bismuth eutectic (LBE) is an important problem which depends, amongst other things, on the diffusion of the steel components inside this liquid alloy. Here we present the results of classical molecular dynamics simulations of the diffusion of Fe and Ni within LBE. The simulations complement experimental studies of impurity diffusion by our group and provide an atomic-level understanding of the relevant diffusion phenomena. They are based on the embedded atom method (EAM) to represent many-body interactions among atoms. The EAM potentials employed in our simulations have been validated against ab initio density functional calculations. We show that the experimental and simulation results for the temperature-dependent viscosity of LBE and the impurity diffusion coefficients can be reconciled by assuming that the Ni and Fe diffuse mainly as nanoscopic clusters below 1300 K. The average Fe and Ni cluster sizes decrease with increasing the temperature and there is essentially single-atom diffusion at higher temperatures.

Summaries of Papers Presented at the Optical Computing Topical Meeting Held in Salt Lake City, Utah on 27 February thru 1 March 1989

DTIC Science & Technology

1989-12-31

interference rejection fo wideband OPENING REMARKS receiver systems. A time/space integrating optical architec- Alexander A. Sawchuk, University of...electroabsorptive self-electrooptic-effect devices on a single ZnS interference filter is proposed. (p. 385) are attractive for 2-D arrays for switching and...photorefractive crystal as shown in figure 1. The mutual interference between the two sets of beams produces the desired outer-product matrix W = uv-iW

Electroabsorption Spectroscopy Measurements of the Exciton Binding Energy, ElectronHole Reduced Effective Mass, and Band Gap in the Perovskite CHsub3NHsub3PbIsub3

DTIC Science & Technology

2016-07-28

can essentially be described in terms of free carrier generation . KEYWORDS: solar cell, photovoltaic, Franz−Keldysh effect, Wannier exciton, Stark...optoelectronic devices such as lasers,1,2 LEDs,3 and solar cells,4−6 despite requiring only inexpensive and relatively crude processing conditions...compared to current high-performance crystalline semiconductors. The archetypal material, CH3NH3PbI3, has exhibited excellent power con- version

Acoustic phonon dephasing in shallow GaAs/Ga 1- xAl xAs single quantum wells

NASA Astrophysics Data System (ADS)

Cassabois, G.; Meccherini, S.; Roussignol, Ph.; Bogani, F.; Gurioli, M.; Colocci, M.; Planel, R.; Thierry-Mieg, V.

1998-07-01

The intermediate dimensionality regime is studied on a set of shallow GaAs/Ga 1- xAl xAs single quantum wells. Such heterostructures exhibit 2D strong excitonic electroabsorption together with near 3D fast transport properties. We report dephasing time measurements ( T2) of the heavy-hole exciton and we show that the acoustic phonon contribution decreases with x to a value in good agreement with theoretical predictions for GaAs bulk.

Modeling Interfacial Thermal Boundary Conductance of Engineered Interfaces

DTIC Science & Technology

2014-08-31

melting / recrystallization of the subsurface Ag/Cu interface. Observed the formation of a novel, lattice-mismatched interfacial microstruc- ture...calculations were converged within 1 × 10−4 Ryd with respect to wave function cutoff energy, energy density cutoff, and k- point sampling. The A-EAM

Developing a Large Lexical Database for Information Retrieval, Parsing, and Text Generation Systems.

ERIC Educational Resources Information Center

Conlon, Sumali Pin-Ngern; And Others

1993-01-01

Important characteristics of lexical databases and their applications in information retrieval and natural language processing are explained. An ongoing project using various machine-readable sources to build a lexical database is described, and detailed designs of individual entries with examples are included. (Contains 66 references.) (EAM)

Teens in Transition: A Workshop on Teen Sexuality and AIDS for Youth-Serving Professionals.

ERIC Educational Resources Information Center

Deveny, Mary Alice

1993-01-01

Provides excerpts from a presentation at a librarians' continuing education workshop on teen sexuality and AIDS (Acquired Immune Deficiency Syndrome), together with participants questions and comments. Goals of an HIV (Human Immunodeficiency Virus) education program are presented, and activities for librarians are suggested. (EAM)

Developing a New Thesaurus for Art and Architecture.

ERIC Educational Resources Information Center

Petersen, Toni

1990-01-01

This description of the development of the Art and Architecture Thesaurus from 1979 to the present explains the processes and policies that were used to construct a language designed to represent knowledge in art and architecture, as well as to be a surrogate for the image and object being described. (EAM)

OCLC Looks to an Online Future: An Interview with K. Wayne Smith.

ERIC Educational Resources Information Center

Arnold, Stephen

1993-01-01

Provides an interview with K. Wayne Smith, chief executive officer of OCLC, that focuses on OCLC's online reference services. Topics include the ratio between technical and online reference services, how OCLC fits into the online industry, telecommunications, electronic publishing, pricing, database tape leases, and CD-ROM. (EAM)

PC Vendor Viability, or Whatever Happened to HiTech International?

ERIC Educational Resources Information Center

Crawford, Walt

1993-01-01

Reports on the feasibility of vendors of IBM PC compatible computers based on issues of "PC Magazine" from September 1985 to the present. Results by year are given in tabular and text form. Implications of orphan systems for libraries, advertising problems, and predictors of success are discussed. (EAM)

Technology Watch and Competitive Intelligence: A New Challenge in Education for Information.

ERIC Educational Resources Information Center

Dou, Henri; And Others

1993-01-01

Discusses the need for education of information professionals in France to change because of changing needs for scientific, technological, and economic information. The functions of technology watch and competitive intelligence based on an organization's critical success factor are shown to be important. (13 references) (EAM)

The Descriptive Challenges of Fiber Art.

ERIC Educational Resources Information Center

Lunin, Lois F.

1990-01-01

A definition of fiber art, its history, materials and techniques, vocabularies, and creators and users of those vocabularies offer background for understanding the problems in preparing surrogates of this relatively recent art form for text and image databases. Four examples of fiber image information systems are described. (32 references) (EAM)

Technology-Driven Resource Sharing: Paying for Improvement.

ERIC Educational Resources Information Center

Rush, James E.

1993-01-01

Addresses the inadequacies of traditional methods of library financing and proposes a strategy to be implemented in an environment supported by automation and networks. Publisher pricing of data rather than publications, options for charging library users with debit cards, and the role of regional library networks are discussed. (EAM)

Alienation Theory: Application of a Conceptual Framework to a Study of Information among Janitors.

ERIC Educational Resources Information Center

Chatman, Elfreda A.

1990-01-01

Alienation theory was applied to a study of information behavior among 51 janitors. Results showed that they lack an informal information network because of their work schedule, and a perception that their neighbors are undesirable associates and no more informed than they are. (34 references) (EAM)

Citation Analysis of "Geochimica et Cosmochimica Acta," 1951-1960.

ERIC Educational Resources Information Center

Lifshin, Arthur

1993-01-01

A citation analysis of the first 10 years of "Geochimica et Cosmochimica Acta" from 1951 to 1960 is described. A shift from German to English language citations and the emerging importance of the journal in the field, which is undergoing a change resulting from technological innovation, are shown. Tables and graphs are included. (EAM)

An Exploration of the Professional Competencies Required in Engineering Asset Management

ERIC Educational Resources Information Center

Bish, Adelle J.; Newton, Cameron J.; Browning, Vicky; O'Connor, Peter; Anibaldi, Renata

2014-01-01

Engineering asset management (EAM) is a rapidly growing and developing field. However, efforts to select and develop engineers in this area are complicated by our lack of understanding of the full range of competencies required to perform. This exploratory study sought to clarify and categorise the professional competencies required of individuals…

Information Distribution Practices of Federal Statistical Agencies: The Census Bureau Example.

ERIC Educational Resources Information Center

Gey, Frederick C.

1993-01-01

Describes the current and historical distribution channels of the U.S. Bureau of the Census within a framework of distribution policies and practices for federal statistical information. The issues of reasonable distribution policies and the impact of technological change are discussed, and guidelines are offered. (Contains 26 references.) (EAM)

Toolbox or Adjustable Spanner? A Critical Comparison of Two Metaphors for Adaptive Decision Making

ERIC Educational Resources Information Center

Söllner, Anke; Bröder, Arndt

2016-01-01

For multiattribute decision tasks, different metaphors exist that describe the process of decision making and its adaptation to diverse problems and situations. Multiple strategy models (MSMs) assume that decision makers choose adaptively from a set of different strategies (toolbox metaphor), whereas evidence accumulation models (EAMs) hold that a…

Gender identity better than sex explains individual differences in episodic and semantic components of autobiographical memory and future thinking.

PubMed

Compère, Laurie; Rari, Eirini; Gallarda, Thierry; Assens, Adèle; Nys, Marion; Coussinoux, Sandrine; Machefaux, Sébastien; Piolino, Pascale

2018-01-01

A recently tested hypothesis suggests that inter-individual differences in episodic autobiographical memory (EAM) are better explained by individual identification of typical features of a gender identity than by sex. This study aimed to test this hypothesis by investigating sex and gender related differences not only in EAM but also during retrieval of more abstract self-knowledge (i.e., semantic autobiographical memory, SAM, and conceptual self, CS), and considering past and future perspectives. No sex-related differences were identified, but regardless of the sex, feminine gender identity was associated with clear differences in emotional aspects that were expressed in both episodic and more abstract forms of AM, and in the past and future perspectives, while masculine gender identity was associated with limited effects. In conclusion, our results support the hypothesis that inter-individual differences in AM are better explained by gender identity than by sex, extending this assumption to both episodic and semantic forms of AM and future thinking. Copyright © 2017 Elsevier Inc. All rights reserved.

Implementation of metal-friendly EAM/FS-type semi-empirical potentials in HOOMD-blue: A GPU-accelerated molecular dynamics software

DOE PAGES

Yang, Lin; Zhang, Feng; Wang, Cai-Zhuang; ...

2018-01-12

We present an implementation of EAM and FS interatomic potentials, which are widely used in simulating metallic systems, in HOOMD-blue, a software designed to perform classical molecular dynamics simulations using GPU accelerations. We first discuss the details of our implementation and then report extensive benchmark tests. We demonstrate that single-precision floating point operations efficiently implemented on GPUs can produce sufficient accuracy when compared against double-precision codes, as demonstrated in test simulations of calculations of the glass-transition temperature of Cu 64.5Zr 35.5, and pair correlation function of liquid Ni 3Al. Our code scales well with the size of the simulating systemmore » on NVIDIA Tesla M40 and P100 GPUs. Compared with another popular software LAMMPS running on 32 cores of AMD Opteron 6220 processors, the GPU/CPU performance ratio can reach as high as 4.6. In conclusion, the source code can be accessed through the HOOMD-blue web page for free by any interested user.« less

Implementation of metal-friendly EAM/FS-type semi-empirical potentials in HOOMD-blue: A GPU-accelerated molecular dynamics software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Lin; Zhang, Feng; Wang, Cai-Zhuang

We present an implementation of EAM and FS interatomic potentials, which are widely used in simulating metallic systems, in HOOMD-blue, a software designed to perform classical molecular dynamics simulations using GPU accelerations. We first discuss the details of our implementation and then report extensive benchmark tests. We demonstrate that single-precision floating point operations efficiently implemented on GPUs can produce sufficient accuracy when compared against double-precision codes, as demonstrated in test simulations of calculations of the glass-transition temperature of Cu 64.5Zr 35.5, and pair correlation function of liquid Ni 3Al. Our code scales well with the size of the simulating systemmore » on NVIDIA Tesla M40 and P100 GPUs. Compared with another popular software LAMMPS running on 32 cores of AMD Opteron 6220 processors, the GPU/CPU performance ratio can reach as high as 4.6. In conclusion, the source code can be accessed through the HOOMD-blue web page for free by any interested user.« less

Melting curves and entropy of fusion of body-centered cubic tungsten under pressure

NASA Astrophysics Data System (ADS)

Liu, Chun-Mei; Chen, Xiang-Rong; Xu, Chao; Cai, Ling-Cang; Jing, Fu-Qian

2012-07-01

The melting curves and entropy of fusion of body-centered cubic (bcc) tungsten (W) under pressure are investigated via molecular dynamics (MD) simulations with extended Finnis-Sinclair (EFS) potential. The zero pressure melting point obtained is better than other theoretical results by MD simulations with the embedded-atom-method (EAM), Finnis-Sinclair (FS) and modified EAM potentials, and by ab initio MD simulations. Our radial distribution function and running coordination number analyses indicate that apart from the expected increase in disorder, the main change on going from solid to liquid is thus a slight decrease in coordination number. Our entropy of fusion of W during melting, ΔS, at zero pressure, 7.619 J/mol.K, is in good agreement with the experimental and other theoretical data. We found that, with the increasing pressure, the entropy of fusion ΔS decreases fast first and then oscillates with pressure; when the pressure is higher than 100 GPa, the entropy of fusion ΔS is about 6.575 ± 0.086 J/mol.K, which shows less pressure effect.

Sensitivity of Force Fields on Mechanical Properties of Metals Predicted by Atomistic Simulations

NASA Astrophysics Data System (ADS)

Rassoulinejad-Mousavi, Seyed Moein; Zhang, Yuwen

Increasing number of micro/nanoscale studies for scientific and engineering applications, leads to huge deployment of atomistic simulations such as molecular dynamics and Monte-Carlo simulation. Many complains from users in the simulation community arises for obtaining wrong results notwithstanding of correct simulation procedure and conditions. Improper choice of force field, known as interatomic potential is the likely causes. For the sake of users' assurance, convenience and time saving, several interatomic potentials are evaluated by molecular dynamics. Elastic properties of multiple FCC and BCC pure metallic species are obtained by LAMMPS, using different interatomic potentials designed for pure species and their alloys at different temperatures. The potentials created based on the Embedded Atom Method (EAM), Modified EAM (MEAM) and ReaX force fields, adopted from available open databases. Independent elastic stiffness constants of cubic single crystals for different metals are obtained. The results are compared with the experimental ones available in the literature and deviations for each force field are provided at each temperature. Using current work, users of these force fields can easily judge on the one they are going to designate for their problem.

Modeling of point defects and rare gas incorporation in uranium mono-carbide

NASA Astrophysics Data System (ADS)

Chartier, A.; Van Brutzel, L.

2007-02-01

An embedded atom method (EAM) potential has been established for uranium mono-carbide. This EAM potential was fitted on structural properties of metallic uranium and uranium mono-carbide. The formation energies of point defects, as well as activation energies for self migration, have been evaluated in order to cross-check the suitability of the potential. Assuming that the carbon vacancies are the main defects in uranium mono-carbide compounds, the migration paths and energies are consistent with experimental data selected by Catlow[C.R.A. Catlow, J. Nucl. Mater. 60 (1976) 151]. The insertion and migration energies for He, Kr and Xe have also been evaluated with available inter-atomic potentials [H.H. Andersen, P. Sigmund, Nucl. Instr. and Meth. B 38 (1965) 238]. Results show that the most stable defect configuration for rare gases is within uranium vacancies. The migration energy of an interstitial Xe is 0.5 eV, in agreement with the experimental value of 0.5 eV [Hj. Matzke, Science of advanced LMFBR fuels, Solid State Physics, Chemistry and Technology of Carbides, Nitrides and Carbonitrides of Uranium and Plutonium, North-Holland, 1986].

Lattice Stability and Interatomic Potential of Non-equilibrium Warm Dense Gold

NASA Astrophysics Data System (ADS)

Chen, Z.; Mo, M.; Soulard, L.; Recoules, V.; Hering, P.; Tsui, Y. Y.; Ng, A.; Glenzer, S. H.

2017-10-01

Interatomic potential is central to the calculation and understanding of the properties of matter. A manifestation of interatomic potential is lattice stability in the solid-liquid transition. Recently, we have used frequency domain interferometry (FDI) to study the disassembly of ultrafast laser heated warm dense gold nanofoils. The FDI measurement is implemented by a spatial chirped single-shot technique. The disassembly of the sample is characterized by the change in phase shift of the reflected probe resulted from hydrodynamic expansion. The experimental data is compared with the results of two-temperature molecular dynamic simulations based on a highly optimized embedded-atom-method (EAM) interatomic potential. Good agreement is found for absorbed energy densities of 0.9 to 4.3MJ/kg. This provides the first demonstration of the applicability of an EAM interatomic potential in the non-equilibrium warm dense matter regime. The MD simulations also reveal the critical role of pressure waves in solid-liquid transition in ultrafast laser heated nanofoils. This work is supported by DOE Office of Science, Fusion Energy Science under FWP 100182, and SLAC LDRD program.

Detection of picosecond electrical pulses using the intrinsic Franz{endash}Keldysh effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lampin, J. F.; Desplanque, L.; Mollot, F.

2001-06-25

We report time-resolved measurements of ultrafast electrical pulses propagating on a coplanar transmission line using the intrinsic Franz{endash}Keldysh effect. A low-temperature-grown GaAs layer deposited on a GaAs substrate allows generation and also detection of ps pulses via electroabsorption sampling (EAS). This all-optical method does not require any external sampling probe. A typical rise time of 1.1 ps has been measured. EAS is a good candidate for use in THz characterization of ultrafast devices. {copyright} 2001 American Institute of Physics.

Optically induced excitonic electroabsorption in a periodically delta-doped InGaAs/GaAs multiple quantum well structure

NASA Technical Reports Server (NTRS)

Larsson, A.; Maserjian, J.

1991-01-01

Large optically induced Stark shifts have been observed in a periodically delta-doped InGaAs/GaAs multiple quantum well structure. With an excitation intensity of 10 mW/sq cm, an absolute quantum well absorption change of 7000/cm was measured with a corresponding differential absorption change as high as 80 percent. The associated maximum change in the quantum well refractive index is 0.04. This material is promising for device development for all-optical computing and signal processing.

Small interfering RNA therapy against carbohydrate sulfotransferase 15 inhibits cardiac remodeling in rats with dilated cardiomyopathy.

PubMed

Watanabe, Kenichi; Arumugam, Somasundaram; Sreedhar, Remya; Thandavarayan, Rajarajan A; Nakamura, Takashi; Nakamura, Masahiko; Harima, Meilei; Yoneyama, Hiroyuki; Suzuki, Kenji

2015-07-01

Carbohydrate sulfotransferase 15 (CHST15) is a sulfotransferase responsible for biosynthesis of chondroitin sulfate E (CS-E), which plays important roles in numerous biological events such as biosynthesis of proinflammatory cytokines. However, the effects of CHST15 siRNA in rats with chronic heart failure (CHF) after experimental autoimmune myocarditis (EAM) have not yet been investigated. CHF was elicited in Lewis rats by immunization with cardiac myosin, and after immunization, the rats were divided into two groups and treated with either CHST15 siRNA (2μg/week) or vehicle. Age matched normal rats without immunizations were also included in this study. After 7weeks of treatment, we investigated the effects of CHST15 siRNA on cardiac function, proinflammatory cytokines, and cardiac remodeling in EAM rats. Myocardial functional parameters measured by hemodynamic and echocardiographic studies were significantly improved by CHST15 siRNA treatment in rats with CHF compared with that of vehicle-treated CHF rats. CHST15 siRNA significantly reduced cardiac fibrosis, and hypertrophy and its marker molecules (left ventricular (LV) mRNA expressions of transforming growth factor beta1, collagens I and III, and atrial natriuretic peptide) compared with vehicle-treated CHF rats. CHF-induced increased myocardial mRNA expressions of proinflammatory cytokines [interleukin (IL)-6, IL-1β], monocyte chemoattractant protein-1, and matrix metalloproteinases (MMP-2 and -9), and CHST15 were also suppressed by the treatment with CHST15 siRNA. Western blotting study has confirmed the results obtained from mRNA analysis as CHST15 siRNA treated rats expressed reduced levels of inflammatory and cardiac remodeling marker proteins. Our results demonstrate for the first time, that CHST15 siRNA treatment significantly improved LV function and ameliorated the progression of cardiac remodeling in rats with CHF after EAM. Copyright © 2015 Elsevier Inc. All rights reserved.

Sex Differences in the Neural Correlates of Specific and General Autobiographical Memory

PubMed Central

Compère, Laurie; Sperduti, Marco; Gallarda, Thierry; Anssens, Adèle; Lion, Stéphanie; Delhommeau, Marion; Martinelli, Pénélope; Devauchelle, Anne-Dominique; Oppenheim, Catherine; Piolino, Pascale

2016-01-01

Autobiographical memory (AM) underlies the formation and temporal continuity over time of personal identity. The few studies on sex-related differences in AM suggest that men and women adopt different cognitive or emotional strategies when retrieving AMs. However, none of the previous works has taken into account the distinction between episodic autobiographical memory (EAM), consisting in the retrieval of specific events by means of mental time travel, and semantic autobiographical memory (SAM), which stores general personal events. Thus, it remains unclear whether differences in these strategies depend on the nature of the memory content to be retrieved. In the present study we employed functional MRI to examine brain activity underlying potential sex differences in EAM and SAM retrieval focusing on the differences in strategies related to the emotional aspects of memories while controlling for basic cognitive strategies. On the behavioral level, there was no significant sex difference in memory performances or subjective feature ratings of either type of AM. Activations common to men and women during AM retrieval were observed in a typical bilateral network comprising medial and lateral temporal regions, precuneus, occipital cortex as well as prefrontal cortex. Contrast analyses revealed that there was no difference between men and women in the EAM condition. In the SAM condition, women showed an increased activity, compared to men, in the dorsal anterior cingulate cortex, inferior parietal and precentral gyrus. Overall, these findings suggest that differential neural activations reflect sex-specific strategies related to emotional aspects of AMs, particularly regarding SAM. We propose that this pattern of activation during SAM retrieval reflects the cognitive cost linked to emotion regulation strategies recruited by women compared to men. These sex-related differences have interesting implications for understanding psychiatric disorders with differential sex prevalence and in which one of key features is overgenerality in AM. PMID:27378884

Functional independence within the self-memory system: new insights from two cases of developmental amnesia.

PubMed

Picard, Laurence; Mayor-Dubois, Claire; Maeder, Philippe; Kalenzaga, Sandrine; Abram, Maria; Duval, Céline; Eustache, Francis; Roulet-Perez, Eliane; Piolino, Pascale

2013-06-01

Neuropsychological and neuroimaging data suggest that the self-memory system can be fractionated into three functionally independent systems processing personal information at several levels of abstraction, including episodic memories of one's life (episodic autobiographical memory, EAM), semantic knowledge of facts about one's life (semantic autobiographical memory, SAM), and semantic knowledge of one's personality [conceptual self, (CS)]. Through the study of two developmental amnesic patients suffering of neonatal brain injuries, we explored how the different facets of the self-memory system develop when growing up with bilateral hippocampal atrophy. Neuropsychological evaluations showed that both of them suffered from dramatic episodic learning disability with no sense of recollection (Remember/Know procedure), whereas their semantic abilities differed, being completely preserved (Valentine) or not (Jocelyn). Magnetic resonance imaging, including quantitative volumetric measurements of the hippocampus and adjacent (entorhinal, perirhinal, and temporopolar) cortex, showed severe bilateral atrophy of the hippocampus in both patients, with additional atrophy of adjacent cortex in Jocelyn. Exploration of EAM and SAM according to lifetime periods covering the entire lifespan (TEMPAu task, Piolino et al., 2009) showed that both patients had marked impairments in EAM, as they lacked specificity, details and sense of recollection, whereas SAM was completely normal in Valentine, but impaired in Jocelyn. Finally, measures of patients' CS (Tennessee Self-Concept Scale, Fitts and Warren, 1996), checked by their mothers, were generally within normal range, but both patients showed a more positive self-concept than healthy controls. These two new cases support a modular account of the medial-temporal lobe with episodic memory and recollection depending on the hippocampus, and semantic memory and familiarity on adjacent cortices. Furthermore, they highlight developmental episodic and semantic functional independence within the self-memory system suggesting that SAM and CS may be acquired without episodic memories. Copyright © 2012 Elsevier Ltd. All rights reserved.

Feasibility of zero or near zero fluoroscopy during catheter ablation procedures.

PubMed

Haegeli, Laurent M; Stutz, Linda; Mohsen, Mohammed; Wolber, Thomas; Brunckhorst, Corinna; On, Chol-Jun; Duru, Firat

2018-04-03

Awareness of risks associated with radiation exposure to patients and medical staff has significantly increased. It has been reported before that the use of advanced three-dimensional electro-anatomical mapping (EAM) system significantly reduces fluoroscopy time, however this study aimed for zero or near zero fluoroscopy ablation to assess its feasibility and safety in ablation of atrial fibrillation (AF) and other tachyarrhythmias in a "real world" experience of a single tertiary care center. This was a single-center study where ablation procedures were attempted without fluoroscopy in 34 consecutive patients with different tachyarrhythmias under the support of EAM system. When transseptal puncture (TSP) was needed, it was attempted under the guidance of intracardiac echocardiography (ICE). Among 34 patients consecutively enrolled in this study, 28 (82.4%) patients were referred for radiofrequency ablation (RFA) of AF, 3 (8.8%) patients for ablation of right ventricular outflow tract (RVOT) ventricular extrasystole (VES), 1 (2.9%) patient for ablation of atrioventricular nodal reentry tachycardia (AVNRT), 2 (5.9%) patients for typical atrial flutter ablation. In 21 (62%) patients the entire procedure was carried out without the use of fluoroscopy. Among 28 AF patients, 15 (54%) patients underwent ablation without the use of fluoroscopy and among these 15 patients, 10 (67%) patients required TSP under ICE guidance while 5 (33%) patients the catheters were introduced to left atrium through a patent foramen ovale. In 13 AF patients, fluoroscopy was only required for double TSP. The total procedure time of AF ablation was 130 ± 50 min. All patients referred for atrial flutter, AVNRT, and VES of the RVOT ablation did not require any fluoroscopy. This study demonstrates the feasibility of zero or near zero fluoroscopy procedure including TSP with the support of EAM and ICE guidance in a "real world" experience of a single tertiary care center. When fluoroscopy was required, it was limited to TSP hence keeping the radiation dose very low. .

III-V on silicon micro-photonic circuits for frequency downconversion of RF signals

NASA Astrophysics Data System (ADS)

Roelkens, G.; Keyvaninia, S.; Tassaert, M.; Latkowski, S.; Bente, E.; Mariën, J.; Thomassen, L.; Baets, R.

2017-11-01

RF frequency downconverters are of key importance in communication satellites. Classically, this is implemented using an electronic mixer. In this paper we explore the use of photonic technology to realize the same functionality. The potential advantages of such an approach compared to the classical microwave solutions are that it is lighter weight, has lower power consumption and can be made smaller if photonic technology is used. An additional advantage is the fact that the optical local oscillator (LO) reference can easily be transported over longer distances than the equivalent LO signal in the microwave domain due to the large bandwidth and low loss and dispersion of optical fiber. Another big advantage is that one can envision the use of short pulse trains as the LO - starting off from a sinusoidal RF reference - in order to exploit subsampling. Subsampling avoids the need for high frequency LO references, which is especially valuable if a downconversion over several 10s of GHz is required. In this paper we present the operation principle of such a photonic frequency downconverter and describe the performance of the developed micro-photonic building blocks required for this functionality. These micro-photonic building blocks are implemented on a III-V semiconductor-on-silicon photonic platform. The components include a micro-photonic hybridly modelocked laser, a 30GHz electroabsorption modulator and an intermediate frequency (1.5GHz) photodetector.

Strong quantum-confined Stark effect in a lattice-matched GeSiSn/GeSn multi-quantum-well structure

NASA Astrophysics Data System (ADS)

Peng, Ruizhi; Chunfuzhang; Han, Genquan; Hao, Yue

2017-06-01

This paper presents modeling and simulation of a multiple quantum well structure formed with Ge0.95Sn0.05 quantum wells separated by Ge0.51Si0.35Sn0.14 barriers for the applications. These alloy compositions are chosen to satisfy two conditions simultaneously: type-I band alignment between Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 and a lattice match between wells and barriers. This lattice match ensures that the strain-free structure can be grown upon a relaxed Ge0.51Si0.35Sn0.14 buffer on a silicon substrate - a CMOS compatible process. A electro-absorption modulator with the Ge0.95Sn0.05/Ge0.51Si0.35Sn0.14 multiple quantum well structure based on quantum-confined Stark effect(QCSE) is demonstrated in theory. The energy band diagrams of the GeSiSn/GeSn multi-quantum-well structure at 0 and 0.5V bias are calculated, respectively. And the corresponding absorption coefficients as a function of cut-off energy for this multiple quantum well structure at 0 and 0.5Vbias are also obtained, respectively. The reduction of cut-off energy is observed with the applying of the external electric field, indicating a strong QCSE in the structure.

Harvest-associated disturbance in upland Ozark forests of the Missouri Ozark Forest Ecosystem Project

Treesearch

Johann N. Bruhn; James J. Wetteroff; Jeanne D. Mihail; Randy G. Jensen; James B. Pickens

2002-01-01

The Missouri Ozark Forest Ecosystem Project (MOFEP) is a long-term, multidisciplinary, landscape-based research program studying effects of even-aged (EAM), uneven-aged (UAM), and no-harvest (NHM) management on forest communities. The first MOFEP timber harvests occurred from May through November 1996. Harvest- related disturbance occurred on 69 of 180 permanent 0.2-ha...

12. VIEW OF PUMPS NO. 6, 8, AND 7 (L ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. VIEW OF PUMPS NO. 6, 8, AND 7 (L TO R) WITH THEIR CANVAS COVERS, LOOKING NORTHEAST. NOTE CONCRETE CONSTRUCTION. THE FOUR LIGHT WINDOWS AND THE STEEL EAM FOR THE 10-TON HAND OPERATED TRAVELING CRANE. - Wyoming Valley Flood Control System, Woodward Pumping Station, East of Toby Creek crossing by Erie-Lackawanna Railroad, Edwardsville, Luzerne County, PA

To Learn and Earn: Arizona's Unfinished Business in Human Capital

ERIC Educational Resources Information Center

Welch, Nancy

2009-01-01

Raising Arizona was the challenge of the 20th century. Sustaining Arizona is now the challenge of the 21st. A crucial part of that task is not just understanding today's knowledge economy, but mastering it. Ray and Charles Eames, the creative geniuses behind many iconic 20th century designs, debuted their film "Powers of 10" in 1977. In…

Monitoring the health of selected eastern arc forests in Tanzania

Treesearch

Seif Madoffe; Gerard D. Hertel; Paul Rodgers [Rogers; Barbra [Barbara] O' Connel; Raymond Killenga

2006-01-01

The eastern arc mountains (EAMs) are a chain of isolated mountains (534,000 ha) in Kenya and Tanzania surrounded by arid woodlands and influenced by the Indian Ocean. In 1900 there was three times the amount of forest cover there is today. Much of the original forests have been converted into agricultural crops. These mountains are recognized as a globally important...

Effects of atmospheric air plasma treatment of graphite and carbon felt electrodes on the anodic current from Shewanella attached cells.

PubMed

Epifanio, Monica; Inguva, Saikumar; Kitching, Michael; Mosnier, Jean-Paul; Marsili, Enrico

2015-12-01

The attachment of electrochemically active microorganisms (EAM) on an electrode is determined by both the chemistry and topography of the electrode surface. Pre-treatment of the electrode surface by atmospheric air plasma introduces hydrophilic functional groups, thereby increasing cell attachment and electroactivity in short-term experiments. In this study, we use graphite and carbon felt electrodes to grow the model EAM Shewanella loihica PV-4 at oxidative potential (0.2 V vs. Ag/AgCl). Cell attachment and electroactivity are measured through electrodynamic methods. Atmospheric air plasma pre-treatment increases cell attachment and current output at graphite electrodes by 25%, while it improves the electroactivity of the carbon felt electrodes by 450%. Air plasma pre-treatment decreased the coulombic efficiency on both carbon felt and graphite electrodes by 60% and 80%, respectively. Microbially produced flavins adsorb preferentially at the graphite electrode, and air plasma pre-treatment results in lower flavin adsorption at both graphite and carbon felt electrodes. Results show that air plasma pre-treatment is a feasible option to increase current output in bioelectrochemical systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Hydrogen-vacancy-dislocation interactions in α-Fe

NASA Astrophysics Data System (ADS)

Tehranchi, A.; Zhang, X.; Lu, G.; Curtin, W. A.

2017-02-01

Atomistic simulations of the interactions between dislocations, hydrogen atoms, and vacancies are studied to assess the viability of a recently proposed mechanism for the formation of nanoscale voids in Fe-based steels in the presence of hydrogen. Quantum-mechanics/molecular-mechanics method calculations confirm molecular statics simulations based on embedded atom method (EAM) potential showing that individual vacancies on the compressive side of an edge dislocation can be transported with the dislocation as it glides. Molecular dynamics simulations based on EAM potential then show, however, that vacancy clusters in the glide plane of an approaching dislocation are annihilated or reduced in size by the creation of a double-jog/climb process that is driven by the huge reduction in energy accompanying vacancy annihilation. The effectiveness of annihilation/reduction processes is not reduced by the presence of hydrogen in the vacancy clusters because typical V-H cluster binding energies are much lower than the vacancy formation energy, except at very high hydrogen content in the cluster. Analysis of a range of configurations indicates that hydrogen plays no special role in stabilizing nanovoids against jog formation processes that shrink voids. Experimental observations of nanovoids on the fracture surfaces of steels must be due to as-yet undetermined processes.

High-speed absorption recovery in quantum well diodes by diffusive electrical conduction

NASA Astrophysics Data System (ADS)

Livescu, G.; Miller, D. A. B.; Sizer, T.; Burrows, D. J.; Cunningham, J. E.

1989-02-01

Picosecond time-resolved electroabsorption measurements in GaAs quantum well p-i-n diode structures are presented. While the dynamics of the vertical transport is not completely understood at present, the data reveal the importance of the 'lateral' propagatin of the photoexcited voltage pulse over the area of the doped regions. A two-dimensional 'diffusive conduction' mechanism is proposed which predicts a fast relaxation of the electrical pulse, with time constants ranging from 50 fs to 500 ps, determined by the size of the exciting spot, the resistivity of the doped regions, and the capacitance of the intrinsic region.

Changes in ground layer vegetation following timber harvests on the Missouri Ozark Forest Ecosystem Project

Treesearch

Jennifer K. Grabner; Eric K. Zenner

2002-01-01

The Missouri Ozark Forest Ecosystem Project (MOFEP) is a landscape-scale experiment to test for effects of the following three common forest management practices on upland forests: 1) even-aged management (EAM), 2) uneven-aged management (UAM), and 3) no-harvest management (NHM). The first round of harvesting treatments was applied on the nine MOFEP sites in 1996. One...

Effects of Perceived Racism and Sexism on Psychological Well Being and the Moderating Effects of Identity Development among African and European American College Students.

ERIC Educational Resources Information Center

Highlen, Pamela S.; Tom, David M.; Ashton, Kathleen R.; Thompson, Kenya I.

The combined and singular effects of racism and sexism on African American females (AAF), males (AAM), and European American females (EAF) are examined with identity development as a moderator of psychological well being. Samples of AAF, AAM, EAF and a control group of European American Males (EAM) completed counterbalanced instruments that…

Habitation Concepts for Human Missions Beyond Low-Earth-Orbit

NASA Technical Reports Server (NTRS)

Smitherman, David V.

2016-01-01

The Advanced Concepts Office at the NASA Marshall Space Flight Center has been engaged for several years in a variety of study activities to help define various options for deep space habitation. This work includes study activities supporting asteroid, lunar and Mars mission activities for the Human spaceflight Architecture Team (HAT), the Deep Space Habitat (DSH) project, and the Exploration Augmentation Module (EAM) project through the NASA Advanced Exploration Systems (AES) Program. The missions under consideration required human habitation beyond low-Earth-orbit (LEO) including deep space habitation in the lunar vicinity to support asteroid retrieval missions, human and robotic lunar surface missions, deep space research facilities, Mars vehicle servicing, and Mars transit missions. Additional considerations included international interest and near term capabilities through the International Space Station (ISS) and Space Launch System (SLS) programs. A variety of habitat layouts have been considered, including those derived from the existing ISS systems, those that could be fabricated from SLS components, and other approaches. This paper presents an overview of several leading designs explored in late fiscal year (FY) 2015 for asteroid, lunar, and Mars mission habitats and identifies some of the known advantages and disadvantages inherent in each. Key findings indicate that module diameters larger than those used for ISS can offer lighter structures per unit volume, and sufficient volume to accommodate consumables for long-duration missions in deep space. The information provided with the findings includes mass and volume data that should be helpful to future exploration mission planning and deep space habitat design efforts.

Vibronic structure and coupling of higher excited electronic states in carotenoids

NASA Astrophysics Data System (ADS)

Krawczyk, Stanisław; Luchowski, Rafał

2013-03-01

Absorption spectra of all-trans carotenoids (lycopene, violaxanthin, ζ-carotene) at low temperature exhibit peculiar features in the UV range. The transition to the 11Ag+ state ('cis-band') weakens on cooling, indicating that it is induced by thermal deformations of the conjugated chain. The higher energy band has unique vibrational structure indicating the vibronic coupling of nBu with another electronic state. The electroabsorption spectra point to the electric field-induced mixing of the nBu state with the vibrational continuum of a lower-lying excited state (Fano effect). These observations widen the basis for elucidation of the vibronic coupling effects in the lower excited states.

Molecular dynamics simulations of the melting curve of NiAl alloy under pressure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wenjin; Peng, Yufeng; Liu, Zhongli, E-mail: zhongliliu@yeah.net

2014-05-15

The melting curve of B2-NiAl alloy under pressure has been investigated using molecular dynamics technique and the embedded atom method (EAM) potential. The melting temperatures were determined with two approaches, the one-phase and the two-phase methods. The first one simulates a homogeneous melting, while the second one involves a heterogeneous melting of materials. Both approaches reduce the superheating effectively and their results are close to each other at the applied pressures. By fitting the well-known Simon equation to our melting data, we yielded the melting curves for NiAl: 1783(1 + P/9.801){sup 0.298} (one-phase approach), 1850(1 + P/12.806){sup 0.357} (two-phase approach).more » The good agreement of the resulting equation of states and the zero-pressure melting point (calc., 1850 ± 25 K, exp., 1911 K) with experiment proved the correctness of these results. These melting data complemented the absence of experimental high-pressure melting of NiAl. To check the transferability of this EAM potential, we have also predicted the melting curves of pure nickel and pure aluminum. Results show the calculated melting point of Nickel agrees well with experiment at zero pressure, while the melting point of aluminum is slightly higher than experiment.« less

Analysis of fcc metals fracture behaviour: Fracture behaviour of fcc metals: brittle/ductile behaviour criteria : with ab-initio, embedded atom and pseudopotential parameterization for Au, Ir and Al. analysis for Au, Ir and Al.

NASA Astrophysics Data System (ADS)

Gornostyrev, Yu. N.; Katsnelson, M. I.; Mryasov, Oleg N.; Freeman, A. J.; Trefilov, M. V.

1998-03-01

Theoretical analysis of the fracture behaviour of fcc Au, Ir and Al have been performed within various brittle/ductile criteria (BDC) with ab-initio, embedded atom (EAM), and pseudopotential parameterizations. We systematically examined several important aspects of the fracture behaviour: (i) dislocation structure, (ii) energetics of the cleavage decohesion and (iii) character of the interatomic interactions. Unit dislocation structures were analyzed within a two dimensional generalization of the Peierls-Nabarro model with restoring forces determined from ab-initio total energy calculations and found to be split with well defined highly mobile partials for all considered metals. We find from ab-initio and pseudopotential that in contrast with most of fcc metals, cleavage decohesion curve for Al appreciably differs from UBER relation. Finally, using ab-initio, EAM and pseudopotential parameterizations, we demonstrate that (i) Au (as a typical example of a ductile metal) is well described within existing BDC's, (ii) anomalous cleavage-like crack propagation of Ir is driven predominantly by it's high elastic modulus and (iii) Al is not described within BDC due to it's long-range interatomic interactions (and hence requires adjustments of the brittle/ductile criteria).

The role of East Asian monsoon system in shaping population divergence and dynamics of a constructive desert shrub Reaumuria soongarica

PubMed Central

Yin, Hengxia; Yan, Xia; Shi, Yong; Qian, Chaoju; Li, Zhonghu; Zhang, Wen; Wang, Lirong; Li, Yi; Li, Xiaoze; Chen, Guoxiong; Li, Xinrong; Nevo, Eviatar; Ma, Xiao-Fei

2015-01-01

Both of the uplift of Qinghai-Tibet Plateau (QTP) and the development of East Asian monsoon system (EAMS) could have comprehensively impacted the formation and evolution of Arid Central Asia (ACA). To understand how desert plants endemic to ACA responded to these two factors, we profiled the historical population dynamics and distribution range shift of a constructive desert shrub Reaumuria soongarica (Tamaricaceae) based on species wide investigation of sequence variation of chloroplast DNA and nuclear ribosomal ITS. Phylogenetic analysis uncovered a deep divergence occurring at ca. 2.96 Mya between the western and eastern lineages of R. soongarica, and ecological niche modeling analysis strongly supported that the monsoonal climate could have fragmented its habitats in both glacial and interglacial periods and impelled its intraspecific divergence. Additionally, the population from the east monsoonal zone expanded rapidly, suggesting that the local monsoonal climate significantly impacted its population dynamics. The isolation by distance tests supported strong maternal gene flow along the direction of the East Asian winter monsoon, whose intensification induced the genetic admixture along the latitudinal populations of R. soongarica. Our results presented a new case that the development of EAMS had prominently impacted the intraspecific divergence and population dynamics of this desert plant. PMID:26510579

A novel oscillation control for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation technique

NASA Astrophysics Data System (ADS)

Ma, Wei; Lin, Yiyu; Liu, Siqi; Zheng, Xudong; Jin, Zhonghe

2017-02-01

This paper reports a novel oscillation control algorithm for MEMS vibratory gyroscopes using a modified electromechanical amplitude modulation (MEAM) technique, which enhances the robustness against the frequency variation of the driving mode, compared to the conventional EAM (CEAM) scheme. In this approach, the carrier voltage exerted on the proof mass is frequency-modulated by the drive resonant frequency. Accordingly, the pick-up signal from the interface circuit involves a constant-frequency component that contains the amplitude and phase information of the vibration displacement. In other words, this informational detection signal is independent of the mechanical resonant frequency, which varies due to different batches, imprecise micro-fabrication and changing environmental temperature. In this paper, the automatic gain control loop together with the phase-locked loop are simultaneously analyzed using the averaging method and Routh-Hurwitz criterion, deriving the stability condition and the parameter optimization rules of the transient response. Then, a simulation model based on the real system is set up to evaluate the control algorithm. Further, the proposed MEAM method is tested using a field-programmable-gate-array based digital platform on a capacitive vibratory gyroscope. By optimizing the control parameters, the transient response of the drive amplitude reveals a settling time of 45.2 ms without overshoot, according well with the theoretical prediction and simulation results. The first measurement results show that the amplitude variance of the drive displacement is 12 ppm in an hour while the phase standard deviation is as low as 0.0004°. The mode-split gyroscope operating under atmospheric pressure demonstrates an outstanding performance. By virtue of the proposed MEAM method, the bias instability and angle random walk are measured to be 0.9° h-1 (improved by 2.4 times compared to the CEAM method) and 0.068° (√h)-1 (improved by 1.4 times), respectively.

SU-C-202-03: A Tool for Automatic Calculation of Delivered Dose Variation for Off-Line Adaptive Therapy Using Cone Beam CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, B; Lee, S; Chen, S

Purpose: Monitoring the delivered dose is an important task for the adaptive radiotherapy (ART) and for determining time to re-plan. A software tool which enables automatic delivered dose calculation using cone-beam CT (CBCT) has been developed and tested. Methods: The tool consists of four components: a CBCT Colleting Module (CCM), a Plan Registration Moduel (PRM), a Dose Calculation Module (DCM), and an Evaluation and Action Module (EAM). The CCM is triggered periodically (e.g. every 1:00 AM) to search for newly acquired CBCTs of patients of interest and then export the DICOM files of the images and related registrations defined inmore » ARIA followed by triggering the PRM. The PRM imports the DICOM images and registrations, links the CBCTs to the related treatment plan of the patient in the planning system (RayStation V4.5, RaySearch, Stockholm, Sweden). A pre-determined CT-to-density table is automatically generated for dose calculation. Current version of the DCM uses a rigid registration which regards the treatment isocenter of the CBCT to be the isocenter of the treatment plan. Then it starts the dose calculation automatically. The AEM evaluates the plan using pre-determined plan evaluation parameters: PTV dose-volume metrics and critical organ doses. The tool has been tested for 10 patients. Results: Automatic plans are generated and saved in the order of the treatment dates of the Adaptive Planning module of the RayStation planning system, without any manual intervention. Once the CTV dose deviates more than 3%, both email and page alerts are sent to the physician and the physicist of the patient so that one can look the case closely. Conclusion: The tool is capable to perform automatic dose tracking and to alert clinicians when an action is needed. It is clinically useful for off-line adaptive therapy to catch any gross error. Practical way of determining alarming level for OAR is under development.« less

Identification of Combat Unit Leader Skills and Leader-Group Interaction Processes

DTIC Science & Technology

1980-01-01

Categories of human learning. New York: Academic Press, 1964. Galton , (Sir) Francis . Hereditary genius. l-itmillan and Company, London, 1879. Garland...naissance tEam was given the mission to acquire intelligence on enemy activities in a particular area of operation (Jones, 1969). The team was to avoid...contact as the mission was strictly one of gathering intelligence . The team operating in the assigned reconnaisspnce zone came upon approximately 15 NVA

Scaling single-wavelength optical interconnects to 180 Gb/s with PAM-M and pulse shaping

NASA Astrophysics Data System (ADS)

Dris, Stefanos; Bakopoulos, Paraskevas; Argyris, Nikolaos; Spatharakis, Christos; Avramopoulos, Hercules

2016-03-01

Faced with surging datacenter traffic demand, system designers are turning to multi-level optical modulation with direct detection as the means of reaching 100 Gb/s in a single optical lane; a further upgrade to 400 Gb/s is envisaged through wavelength-multiplexing of multiple 100 Gb/s strands. In terms of modulation formats, PAM-4 and PAM-8 are considered the front-runners, striking a good balance between bandwidth-efficiency and implementation complexity. In addition, the emergence of energy-efficient, high-speed CMOS digital-to-analog converters (DACs) opens up new possibilities: Spectral shaping through digital filtering will allow squeezing even more data through low-cost, low-bandwidth electro-optic components. In this work we demonstrate an optical interconnect based on an EAM that is driven directly with sub-volt electrical swing by a 65 GSa/s arbitrary waveform generator (AWG). Low-voltage drive is particularly attractive since it allows direct interfacing with the switch/server ASIC, eliminating the need for dedicated, power-hungry and expensive electrical drivers. Single-wavelength throughputs of 180 and 120 Gb/s are experimentally demonstrated with 60 Gbaud optical PAM-8 and PAM-4 respectively. Successful transmission over 1250 m SMF is achieved with direct-detection, using linear equalization via offline digital signal processing in order to overcome the strong bandwidth limitation of the overall link (~20 GHz). The suitability of Nyquist pulse shaping for optical interconnects is also investigated experimentally with PAM-4 and PAM-8, at a lower symbol rate of 40 Gbaud (limited by the sampling rate of the AWG). To the best of our knowledge, the rates achieved are the highest ever using optical PAM-M formats.

Reconstructing Eolian Delivery to the Ulleung Basin (IODP Site U1430) Over the Past 12 Myr

NASA Astrophysics Data System (ADS)

Anderson, C. H.; Dunlea, A. G.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2017-12-01

Spring storms associated with the seasonal phases of the East Asian Monsoon (EAM), transport dust seaward and influence marine sedimentation in adjacent ocean regions. Here, we aim to track changes in the intensity of the EAM since the late Miocene by examining the relative proportions and sources of eolian inputs in marine sediment records. We use bulk sediment recovered from Site U1430 in the Ulleung Basin during Integrated Ocean Drilling Program Expedition 346 in 2013 to examine changes in the EAM over the past 12 Myr. Sediment recovered at this site is clayey silt, nannofossil and diatom oozes, claystone, and basal glauonitic sandstone. We analyze major, trace, and rare earth element concentrations for 72 bulk sediment samples analyzed by ICP-ES and ICP-MS, and interpret this dataset using a variety of multivariate statistical partitioning techniques (Q-mode Factor Analyses (QFA), Multiple Linear Regressions) to investigate sediment provenance. Sedimentologic observations and elemental concentrations indicate the presence of biogenic siliceous and carbonaceous components mixed with aluminosilicates. For example, Si/Al (g/g) reaches local maxima at 3 Ma and 10 Ma in several diatom rich sections, and Ca/Al (g/g) exhibits a peak at 0.58 Ma. Other downhole element ratios exhibit subtle variations, including Ti/Al of 0.05 +/- 0.004 g/g, Sc/Al 2 +/- 0.2 ug/g, and Rb/Al 17 +/- 1.5 ug/g. When plotted in ternary diagrams, samples exhibit offset arrays (La-Th-Sc) or multiple clusters (Zr-Nb-Sc) from an Upper Continental Crust and Mid-Ocean Ridge Basalt mixing line. In Th-Cr-Nb, the data exhibit a V-shaped array. The range of geochemical variability suggests that multiple sources of terrigenous matter and/or volcanic ash are being delivered to the site. The multivariate statistics also indicate the mixing of multiple aluminosilicate sources. Focusing on a suite of seven elements (Al, Ti, Sc, Cr, Rb, Th, La), preliminary QFA suggest that five factors are required to explain 99% of the variability in the dataset. Factors group different co-varying elements: Factor 1 Zr and Th, Factor 2 only Cr, Factor 3 Sc and La, Factor 4 Al and Sc, and Factor 5 with Rb and Th. Terrigenous inputs are likely from several sources including loess and other continental crustal material, and will be discussed further.

Provenance of Continental Margin Sediments in the East China Sea, Results from IODP Expedition 346

NASA Astrophysics Data System (ADS)

Anderson, C. H.; Dunlea, A. G.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2016-12-01

Sedimentation in the East China Sea (ECS) is driven largely by fluvial and eolian fluxes that are likely influenced by the East Asian Monsoon (EAM). Seasonal shifts and long term trends in the atmospheric and precipitation regimes over Asia are recorded in the inorganic chemistry of the sediment of the ECS and other Asian coastal seas. Changes in the intensity and timing of the EAM over a variety of time scales may impact the relative proportion of fluvial and eolian inputs into the ECS, and perhaps even their individual sources. We utilize bulk sediment recovered from IODP Sites U1428 and U1429 in the ECS during IODP Expedition 346 in 2013 to examine changes in the EAM over the past 400ky. Sites U1428 and U1429 are located in the northernmost portion of the ECS in the Danjo Basin, and are separated by 7.4 km. We present major, trace and rare earth element (REE) data for 83 bulk sediment samples analyzed by ICP-ES and ICP-MS, and interpret this data set using a variety of geochemical approaches in addition to multivariate statistics (Q-mode Factor Analyses, Multiple Linear Regressions) to investigate the provenance of terrigenous material during the Pleistocene. We focus on a suite of nine elements that are associated with terrigenous components (Al, Ti, Sc, Cr, Ni, Zn, Rb, Th, La), and that are expected to reflect potential changes in provenance. At both sites average downhole major element ratios exhibit limited variation, but indicate mixing between multiple compositional sources. Ternary diagrams utilizing La-Th-Sc and Rb-Sc-Zn diagrams suggest crustal mixing between three or more sources including upper continental and mafic inputs. Our multivariate statistical data exploration consistently indicates four statistically robust end members explaining 99% of total data variability when we treat these sites as a combined regional signal. Considering each site separately, the four end members are joined by additional fifth end member at each site; highlighting variation in Cr or Ti depending on the site. Inputs from different upper crustal sources and most likely including refractory sands are the most likely contributors to the bulk sediment. Additional results from further statistical analysis will also be presented.

Provenance Changes Over Glacial-Interglacial Timescales Recorded in Japan Sea Sediments (IODP Site U1430)

NASA Astrophysics Data System (ADS)

Kinsley, C. W.; McGee, D.; Anderson, C. H.; Murray, R. W.; Tada, R.; Alvarez Zarikian, C. A.

2017-12-01

Recent work has shown a mechanistic relationship between the Westerly Jet (WJ) and East Asian Monsoon (EAM) precipitation, as migration of the WJ to the northern edge of the Tibetan Plateau during spring and early summer appears to be essential for driving convective rainfall over eastern China. Chiang et al. (2015) has proposed the "Jet Transition Hypothesis" wherein it is put forward that changes to the seasonal meridional position of the WJ relative to the Tibetan Plateau drives rainfall climate changes over East Asia on paleoclimate timescales. This hypothesis would predict that in extreme scenarios such as cold phases of Dansgaard-Oeschger (D-O) stadials and during periods of low Northern Hemisphere summer insolation that the Jet would not move north of the Tibetan Plateau, keeping East Asia in prolonged spring conditions. Conversely, during periods of high Northern Hemisphere summer insolation it would be predicted that the Jet would move more quickly north of the Tibetan Plateau and remain there longer, keeping East Asia in prolonged summer conditions. Westerly Jet behavior can be reconstructed using sediments from the Japan Sea, as the WJ path and intensity determines dust emissions and transport paths from Chinese and Mongolian dust source areas, which is the primary source of terrigenous material to the Japan Sea. Radiogenic isotopes of Pb, Nd and Sr can be been applied to fingerprint the dust sources from Asia, and measurements of these isotopes downcore in the Japan Sea will allow reconstruction of the changing dust source area and thus behavior of the WJ. By coupling dust reconstructions lending insight to the behavior of the Westerly Jet with complementary records reflecting EAM intensity and precipitation distribution, the mean state and variability of the WJ and its coupling with the EAM can be examined. This study will measure a suite of samples for Pb, Nd and Sr isotopes from IODP Site U1430 over glacial-interglacial timescales, allowing detailed insights into changes in eolian sediment source regions in the Japan Sea and laying a foundation for future work examining millennial- and orbital-scale variability. Chiang, J.C.H., et al. 2015. Role of Seasonal Transitions and Westerly Jets in East Asian Paleoclimate, QSR, 108, 111-129.

Atomistic simulations of deformation mechanisms in ultralight weight Mg-Li alloys

NASA Astrophysics Data System (ADS)

Karewar, Shivraj

Mg alloys have spurred a renewed academic and industrial interest because of their ultra-light-weight and high specific strength properties. Hexagonal close packed Mg has low deformability and a high plastic anisotropy between basal and non-basal slip systems at room temperature. Alloying with Li and other elements is believed to counter this deficiency by activating non-basal slip by reducing their nucleation stress. In this work I study how Li addition affects deformation mechanisms in Mg using atomistic simulations. In the first part, I create a reliable and transferable concentration dependent embedded atom method (CD-EAM) potential for my molecular dynamics study of deformation. This potential describes the Mg-Li phase diagram, which accurately describes the phase stability as a function of Li concentration and temperature. Also, it reproduces the heat of mixing, lattice parameters, and bulk moduli of the alloy as a function of Li concentration. Most importantly, our CD-EAM potential reproduces the variation of stacking fault energy for basal, prismatic, and pyramidal slip systems that in uences the deformation mechanisms as a function of Li concentration. This success of CD-EAM Mg-Li potential in reproducing different properties, as compared to literature data, shows its reliability and transferability. Next, I use this newly created potential to study the effect of Li addition on deformation mechanisms in Mg-Li nanocrystalline (NC) alloys. Mg-Li NC alloys show basal slip, pyramidal type-I slip, tension twinning, and two-compression twinning deformation modes. Li addition reduces the plastic anisotropy between basal and non-basal slip systems by modifying the energetics of Mg-Li alloys. This causes the solid solution softening. The inverse relationship between strength and ductility therefore suggests a concomitant increase in alloy ductility. A comparison of the NC results with single crystal deformation results helps to understand the qualitative and quantitative effect of Li addition in Mg on nucleation stress and fault energies of each deformation mode. The nucleation stress and fault energies of basal dislocations and compression twins in single crystal Mg-Li alloy increase while those for pyramidal dislocations and tension twinning decrease. This variation in respective values explains the reduction in plastic anisotropy and increase in ductility for Mg-Li alloys.

Photorefractive InGaAs/GaAs multiple quantum wells in the Franz{endash}Keldysh geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iwamoto, S.; Kageshima, H.; Yuasa, T.

2001-06-01

We fabricate semi-insulating InGaAs/GaAs multiple quantum wells and observe the excitonic enhancement of the photorefractivity in the Franz{endash}Keldysh geometry at wavelengths of 0.92{endash}0.94 {mu}m. A maximum two-wave mixing gain of 138 cm{sup {minus}1} and a maximum diffraction efficiency of 1.5{times}10{sup {minus}4} are obtained. The saturation intensity and the spatial resolution are also measured by four-wave mixing. The diffraction efficiency is saturated at a high external electric field. The dominant cause of this saturation is the deviation of the excitonic electroabsorption from its quadratic law. {copyright} 2001 American Institute of Physics.

Requirement for Pathogenic IL-23 Signaling Is Restricted to Initiation of Autoimmune Myocarditis

PubMed Central

Wu, Lei; Diny, Nicola L.; Ong, SuFey; Barin, Jobert G.; Hou, Xuezhou; Rose, Noel R.; Talor, Monica V.; Čiháková, Daniela

2016-01-01

Using a mouse model of experimental autoimmune myocarditis (EAM), we showed for the first time that IL-23 stimulation of CD4+ T cells is required only briefly at the initiation of GM-CFS-dependent cardiac autoimmunity. IL-23 signal, acting as a switch, turns on pathogenicity of CD4+ T cells, and becomes dispensable once autoreactivity is established. Il23a−/− mice failed to mount an efficient Th17 response to immunization, and were protected from myocarditis. However, remarkably, transient IL-23 stimulation ex vivo fully restored pathogenicity in otherwise nonpathogenic CD4+ T cells raised from Il23a−/− donors. Thus, IL-23 may no longer be necessary to uphold inflammation in established autoimmune diseases. In addition, we demonstrated that IL-23 induced GM-CSF mediates the pathogenicity of CD4+ T cells in EAM. The neutralization of GM-CSF abrogated cardiac inflammation. However, sustained IL-23 signaling is required to maintain IL-17A production in CD4+ T cells. Despite inducing inflammation in Il23a−/− recipients comparable to WT, autoreactive CD4+ T cells downregulated IL-17A production without persistent IL-23 signaling. This divergence on the controls of GM-CSF-dependent pathogenicity on one side and IL-17A production on the other side may contribute to the discrepant efficacies of anti-IL-23 therapy in different autoimmune diseases. PMID:26660726

Macrophages and cardiac fibroblasts are the main producers of eotaxins and regulate eosinophil trafficking to the heart

PubMed Central

Diny, Nicola L.; Hou, Xuezhou; Barin, Jobert G.; Chen, Guobao; Talor, Monica V.; Schaub, Julie; Russell, Stuart D.; Klingel, Karin; Rose, Noel R.; Čiháková, Daniela

2016-01-01

Cardiac manifestations are a major cause of morbidity and mortality in patients with eosinophil-associated diseases. Eosinophils are thought to play a pathogenic role in myocarditis. We investigated the pathways that recruit eosinophils to the heart using a model of eosinophilic myocarditis, in which experimental autoimmune myocarditis (EAM) is induced in IFNγ−/−IL-17A−/− mice. Two conditions are necessary for efficient eosinophil trafficking to the heart: high eotaxin (CCL11, CCL24) expression in the heart and expression of the eotaxin receptor CCR3 by eosinophils. We identified cardiac fibroblasts as the source of CCL11 in the heart interstitium. CCL24 is produced by F4/80+ macrophages localized at inflammatory foci in the heart. Expression of CCL11 and CCL24 is controlled by Th2 cytokines, IL-4 and IL-13. To determine the relevance of this pathway in humans, we analyzed endomyocardial biopsy samples from myocarditis patients. Expression of CCL11 and CCL26 was significantly increased in eosinophilic myocarditis compared to chronic lymphocytic myocarditis and positively correlated with the number of eosinophils. Thus, eosinophil trafficking to the heart is dependent on the eotaxin-CCR3 pathway in a mouse model of EAM and associated with cardiac eotaxin expression in patients with eosinophilic myocarditis. Blocking this pathway may prevent eosinophil-mediated cardiac damage. PMID:27621211

Mononuclear cell secretome protects from experimental autoimmune myocarditis

PubMed Central

Hoetzenecker, Konrad; Zimmermann, Matthias; Hoetzenecker, Wolfram; Schweiger, Thomas; Kollmann, Dagmar; Mildner, Michael; Hegedus, Balazs; Mitterbauer, Andreas; Hacker, Stefan; Birner, Peter; Gabriel, Christian; Gyöngyösi, Mariann; Blyszczuk, Przemyslaw; Eriksson, Urs; Ankersmit, Hendrik Jan

2015-01-01

Aims Supernatants of serum-free cultured mononuclear cells (MNC) contain a mix of immunomodulating factors (secretome), which have been shown to attenuate detrimental inflammatory responses following myocardial ischaemia. Inflammatory dilated cardiomyopathy (iDCM) is a common cause of heart failure in young patients. Experimental autoimmune myocarditis (EAM) is a CD4+ T cell-dependent model, which mirrors important pathogenic aspects of iDCM. The aim of this study was to determine the influence of MNC secretome on myocardial inflammation in the EAM model. Methods and results BALB/c mice were immunized twice with an alpha myosin heavy chain peptide together with Complete Freund adjuvant. Supernatants from mouse mononuclear cells were collected, dialysed, and injected i.p. at Day 0, Day 7, or Day 14, respectively. Myocarditis severity, T cell responses, and autoantibody formation were assessed at Day 21. The impact of MNC secretome on CD4+ T cell function and viability was evaluated using in vitro proliferation and cell viability assays. A single high-dose application of MNC secretome, injected at Day 14 after the first immunization, effectively attenuated myocardial inflammation. Mechanistically, MNC secretome induced caspase-8-dependent apoptosis in autoreactive CD4+ T cells. Conclusion MNC secretome abrogated myocardial inflammation in a CD4+ T cell-dependent animal model of autoimmune myocarditis. This anti-inflammatory effect of MNC secretome suggests a novel and simple potential treatment concept for inflammatory heart diseases. PMID:23321350

Sensory-Feedback Exoskeletal Arm Controller

NASA Technical Reports Server (NTRS)

An, Bin; Massie, Thomas H.; Vayner, Vladimir

2004-01-01

An electromechanical exoskeletal arm apparatus has been designed for use in controlling a remote robotic manipulator arm. The apparatus, called a force-feedback exoskeleton arm master (F-EAM) is comfortable to wear and easy to don and doff. It provides control signals from the wearer s arm to a robot arm or a computer simulator (e.g., a virtual-reality system); it also provides force and torque feedback from sensors on the robot arm or from the computer simulator to the wearer s arm. The F-EAM enables the wearer to make the robot arm gently touch objects and finely manipulate them without exerting excessive forces. The F-EAM features a lightweight design in which the motors and gear heads that generate force and torque feedback are made smaller than they ordinarily would be: this is achieved by driving the motors to power levels greater than would ordinarily be used in order to obtain higher torques, and by providing active liquid cooling of the motors to prevent overheating at the high drive levels. The F-EAM (see figure) includes an assembly that resembles a backpack and is worn like a backpack, plus an exoskeletal arm mechanism. The FEAM has five degrees of freedom (DOFs) that correspond to those of the human arm: 1. The first DOF is that of the side-to-side rotation of the upper arm about the shoulder (rotation about axis 1). The reflected torque for this DOF is provided by motor 1 via drum 1 and a planar four-bar linkage. 2. The second DOF is that of the up-and-down rotation of the arm about the shoulder. The reflected torque for this DOF is provided by motor 2 via drum 2. 3. The third DOF is that of twisting of the upper arm about its longitudinal axis. This DOF is implemented in a cable remote-center mechanism (CRCM). The reflected torque for this DOF is provided by motor 3, which drives the upper-arm cuff and the mechanism below it. A bladder inflatable by gas or liquid is placed between the cuff and the wearer s upper arm to compensate for misalignment between the exoskeletal mechanism and the shoulder. 4. The fourth DOF is that of flexion and extension of the elbow. The reflected torque for this DOF is provided by motor 4 and drum 4, which are mounted on a bracket that can slide longitudinally by a pin-and-slot engagement with the upper-arm cuff to compensate for slight variations in the position of the kinematic center of the elbow. Attached to drum 4 is an adapter plate to which is attached a CRCM for the lower arm. 5. The lower-arm CRCM implements the fifth DOF, which is the twist of the forearm about its longitudinal axis. Motor 5 provides the reflected torque for this DOF by driving the lower-arm cuff. A rod transmits twist and torsion between the lower-arm cuff and the hand cuff. With this system, the motion of the wearer s joints and the reflected torques applied to these joints can be measured and controlled in a relatively simple manner. This is because the anthropomorphic design of the mechanism imitates the kinematics of the human arm, eliminating the need for kinematic conversion of joint-torque and joint-angle data.

Nonlinear optical and electroabsorption spectra of polydiacetylene crystals and films

NASA Astrophysics Data System (ADS)

Mukhopadhyay, D.; Soos, Z. G.

1996-01-01

Vibronic structure of nonlinear optical (NLO) coefficients is developed within the Condon approximation, displaced harmonic oscillators, and crude adiabatic states. The displacements of backbone modes of conjugated polymers are taken from vibrational data on the ground and 1B excited state. NLO resonances are modeled by three excitations and transition moments taken from Pariser-Parr-Pople (PPP) theory and optimized to polydiacetylene (PDA) spectra in crystals and films, with blue-shifted 1B exciton. The joint analysis of third-harmonic-generation, two-photon absorption, and nondegenerate four-wave-mixing spectra of PDA crystals and films shows weak two-photon absorption to 2A below 1B, leading to overlapping resonances in the THG spectrum, strong two-photon absorption to an nA state some 35% above 1B, and weak Raman resonances in nondegenerate FWM spectra. The full π-π* spectrum contributes to Stark shifts and field-induced transitions, as shown by PPP results for PDA oligomers. The Stark shift dominates high-resolution electroabsorption (EA) spectra of PDA crystals below 10 K. The close correspondence between EA and the first-derivative I'(ω) of the linear absorption above the 1B exciton in PDA crystals provides an experimental separation of vibrational and electronic contributions that limits any even-parity state in this 0.5 eV interval. An oscillator-strength sum rule is applied to the convergence of PDA oligomers with increasing length, N, and the crystal oscillator strengths are obtained without adjustable parameters. The sum rule for the 1B exciton implies large transition moments to higher-energy Ag states, whose locations in recent models are contrasted to PPP results. Joint analysis of NLO and EA spectra clarifies when a few electronic excitations are sufficient, distinguishes between vibrational and electronic contributions, and supports similar π-electron interactions in conjugated molecules and polymers.

Influence of Parameters of a Reactive Interatomic Potential on the Properties of Saturated Hydrocarbons

DTIC Science & Technology

2017-01-01

Methodology 3 2.1 Modified Embedded-Atom Method Theory 3 2.1.1 Embedding Energy Function 3 2.1.2 Screening Factor 8 2.1.3 Modified Embedded-Atom...Simulation Methodology 2.1 Modified Embedded-Atom Method Theory In the EAM and MEAM formalisms1,2,5 the total energy of a system of atoms (Etot) is...An interatomic potential for saturated hydrocarbons using the modified embedded-atom method (MEAM), a semiempirical many-body potential based on

Wind Tunnel Tests of the Space Shuttle Foam Insulation with Simulated Debonded Regions

DTIC Science & Technology

1981-04-01

set identification number Gage sensitivity Calculated gage sen8itivity 82 = Sl * f(TGE) Material specimen identification designation Free-stream...ColoY motion pictures (2 cameras) and pre- and posttest color stills recorded ariy changes "in the samples. The movie cameras were operated at...The oBli ~ue shock wave generated by the -wedge reduces the free-stream Mach nut1ber to the desired local Mach number. Since the free=sti’eam

Metals Subcommittee Report - Manufacturing Technology Advisory Group.

DTIC Science & Technology

1980-01-01

Electric Co, Mr. K. W. Stalker Abex Corp, Mr. W. R. Matschulat TRW Equipment, Mr. John McCarthy General Electric Co, Mr. A. I. Bellin General Electric...Code 6721C Philadelphia, PA 19112 Philadelphia, PA 19112 AV 443-3991, 215-755-3991 AV 443-3285, 215-755-3285 Mr. Howard Miller Mr. Joseph Glatz NAVAIR...DRXIB-MT 793-6586 John Melonas DRSMI-EAM 746-1902 GiovanAi Silvestri NUSC Newport 948-2617 Fred Miller AFML/LTM 785-5037 Howard Miller NAVAIR AIR-5162

Mononuclear cell secretome protects from experimental autoimmune myocarditis.

PubMed

Hoetzenecker, Konrad; Zimmermann, Matthias; Hoetzenecker, Wolfram; Schweiger, Thomas; Kollmann, Dagmar; Mildner, Michael; Hegedus, Balazs; Mitterbauer, Andreas; Hacker, Stefan; Birner, Peter; Gabriel, Christian; Gyöngyösi, Mariann; Blyszczuk, Przemyslaw; Eriksson, Urs; Ankersmit, Hendrik Jan

2015-03-14

Supernatants of serum-free cultured mononuclear cells (MNC) contain a mix of immunomodulating factors (secretome), which have been shown to attenuate detrimental inflammatory responses following myocardial ischaemia. Inflammatory dilated cardiomyopathy (iDCM) is a common cause of heart failure in young patients. Experimental autoimmune myocarditis (EAM) is a CD4+ T cell-dependent model, which mirrors important pathogenic aspects of iDCM. The aim of this study was to determine the influence of MNC secretome on myocardial inflammation in the EAM model. BALB/c mice were immunized twice with an alpha myosin heavy chain peptide together with Complete Freund adjuvant. Supernatants from mouse mononuclear cells were collected, dialysed, and injected i.p. at Day 0, Day 7, or Day 14, respectively. Myocarditis severity, T cell responses, and autoantibody formation were assessed at Day 21. The impact of MNC secretome on CD4+ T cell function and viability was evaluated using in vitro proliferation and cell viability assays. A single high-dose application of MNC secretome, injected at Day 14 after the first immunization, effectively attenuated myocardial inflammation. Mechanistically, MNC secretome induced caspase-8-dependent apoptosis in autoreactive CD4+ T cells. MNC secretome abrogated myocardial inflammation in a CD4+ T cell-dependent animal model of autoimmune myocarditis. This anti-inflammatory effect of MNC secretome suggests a novel and simple potential treatment concept for inflammatory heart diseases. © The Author 2013. Published by Oxford University Press on behalf of the European Society of Cardiology.

Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

PubMed Central

Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

2013-01-01

Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

Phase transitions and kinetic properties of gold nanoparticles confined between two-layer graphene nanosheets

NASA Astrophysics Data System (ADS)

Wang, Gang; Wu, Nanhua; Chen, Jionghua; Wang, Jinjian; Shao, Jingling; Zhu, Xiaolei; Lu, Xiaohua; Guo, Lucun

2016-11-01

The thermodynamic and kinetic behaviors of gold nanoparticles confined between two-layer graphene nanosheets (two-layer-GNSs) are examined and investigated during heating and cooling processes via molecular dynamics (MD) simulation technique. An EAM potential is applied to represent the gold-gold interactions while a Lennard-Jones (L-J) potential is used to describe the gold-GNS interactions. The MD melting temperature of 1345 K for bulk gold is close to the experimental value (1337 K), confirming that the EAM potential used to describe gold-gold interactions is reliable. On the other hand, the melting temperatures of gold clusters supported on graphite bilayer are corrected to the corresponding experimental values by adjusting the εAu-C value. Therefore, the subsequent results from current work are reliable. The gold nanoparticles confined within two-layer GNSs exhibit face center cubic structures, which is similar to those of free gold clusters and bulk gold. The melting points, heats of fusion, and heat capacities of the confined gold nanoparticles are predicted based on the plots of total energies against temperature. The density distribution perpendicular to GNS suggests that the freezing of confined gold nanoparticles starts from outermost layers. The confined gold clusters exhibit layering phenomenon even in liquid state. The transition of order-disorder in each layer is an essential characteristic in structure for the freezing phase transition of the confined gold clusters. Additionally, some vital kinetic data are obtained in terms of classical nucleation theory.

Equilibrium composition of interphase boundaries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wynblatt, P.

1990-01-01

Two modeling approaches have been used to investigate segregation effects at interphase boundaries. The first approach is based on the nearest neighbor bond model, used in conjunction with the regular solution approximation, and is an extension of an earlier framework developed to address segregation phenomena at free surfaces. In order to model a semicoherent interphase boundary, we have employed a second modeling approach, based on Monte Carol simulation, in conjunction with the embedded atom method (EAM). The EAM is a powerful new method for describing interatomic interactions in metallic systems. It includes certain many-body interactions that depend on the localmore » environment of an atom. The Monte Carol approach has been applied to semicoherent interphase boundaries in Cu-Ag-Au alloys dilute in Au. These alloys consist of coexisting Cu-rich and Ag-rich phases, which differ in lattice constant by about 12%, such that good matching across in interface occurs when nine structural units of the Cu-rich phase are opposed to eight structural units of the Ag-rich phase. Thus far, interfaces with two different orientations have been studied: {l brace}001{r brace}-Cu//{l brace}001{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag; and {l brace}111{r brace}-Cu//{l brace}111{r brace}-Ag, {l angle}110{r angle}-Cu//{l angle}110{r angle}-Ag. These two interfaces will be referred to as the (001) and (111) interphase boundaries, for short. 18 refs.« less

Re-Engineering the United States Marine Corps’ Enlisted Assignment Model (EAM)

DTIC Science & Technology

1998-06-01

and Execution button opens the switchboard in Figure 12. This form accesses all of the VBA code that is associated with this form and the code that...the prototype to prompt the user and to inform him of what he is about to do. Each of the buttons that are on these forms is connected to an SQL ...into the field for building a rule are the values 2;3;4;5;6;7. The user can enter an SQL statement that would determine the values or the user could

Real-Time Implementation of Nonlinear Optical Processing Functions.

DTIC Science & Technology

1986-09-30

information capacity) with the nonlinear error correction properties of associative neural nets such as the Hopfield model. Analogies between holography...symnolic ma.Ip’:ation Th.e error correcting -apart" :ty of non" ;n-ar associative merTtnies is necessary for s’uch structu-res Experimerta. results... geometrica snapes in contact ’A,.n a c-:’:ser ’Figure 51a’ ., and a spher:cal 4:verg.ng reference -eam Upion :"um’latlon of t -" c-’gram by the object beam

Built-in potential shift and Schottky-barrier narrowing in organic solar cells with UV-sensitive electron transport layers.

PubMed

Li, Cheng; Credgington, Dan; Ko, Doo-Hyun; Rong, Zhuxia; Wang, Jianpu; Greenham, Neil C

2014-06-28

The performance of organic solar cells incorporating solution-processed titanium suboxide (TiOx) as electron-collecting layers can be improved by UV illumination. We study the mechanism of this improvement using electrical measurements and electroabsorption spectroscopy. We propose a model in which UV illumination modifies the effective work function of the oxide layer through a significant increase in its free electron density. This leads to a dramatic improvement in device power conversion efficiency through several mechanisms - increasing the built-in potential by 0.3 V, increasing the conductivity of the TiOx layer and narrowing the interfacial Schottky barrier between the suboxide and the underlying transparent electrode. This work highlights the importance of considering Fermi-level equilibration when designing multi-layer transparent electrodes.

Excited states and electrochromism of radical cation of the carotenoid astaxanthin

NASA Astrophysics Data System (ADS)

Krawczyk, Stanisław

1998-09-01

Radical cations of the carotenoid astaxanthin were generated by chemical oxidation with Fe(Cl) 3, and their absorption and electroabsorption (Stark) spectra at temperatures about 150 K were recorded in the spectral range from 5900 to 26000 cm -1 (380 to 1700 nm), covering two absorptive electronic transitions from D 0 (ground) to D 1 and D 2 excited states. The changes in static polarizability are negative and equal -40±10 A 3 for D 0→D 1 and -105±15 A 3 for D 0→D 2, pointing that dominant contribution to polarizabilities results from the coupling of D 1 and D 2 with the ground state. An approximate localization of the next excited state with ground-state parity is estimated based on arguments from perturbation theory.

Rotational X-ray angiography: a method for intra-operative volume imaging of the left-atrium and pulmonary veins for atrial fibrillation ablation guidance

NASA Astrophysics Data System (ADS)

Manzke, R.; Zagorchev, L.; d'Avila, A.; Thiagalingam, A.; Reddy, V. Y.; Chan, R. C.

2007-03-01

Catheter-based ablation in the left atrium and pulmonary veins (LAPV) for treatment of atrial fibrillation in cardiac electrophysiology (EP) are complex and require knowledge of heart chamber anatomy. Electroanatomical mapping (EAM) is typically used to define cardiac structures by combining electromagnetic spatial catheter localization with surface models which interpolate the anatomy between EAM point locations in 3D. Recently, the incorporation of pre-operative volumetric CT or MR data sets has allowed for more detailed maps of LAPV anatomy to be used intra-operatively. Preoperative data sets are however a rough guide since they can be acquired several days to weeks prior to EP intervention. Due to positional and physiological changes, the intra-operative cardiac anatomy can be different from that depicted in the pre-operative data. We present an application of contrast-enhanced rotational X-ray imaging for CT-like reconstruction of 3D LAPV anatomy during the intervention itself. Depending on the heart size a single or two selective contrastenhanced rotational acquisitions are performed and CT-like volumes are reconstructed with 3D filtered back projection. In case of dual injection, the two volumes depicting the left and right portions of the LAPV are registered and fused. The data sets are visualized and segmented intra-procedurally to provide anatomical data and surface models for intervention guidance. Our results from animal and human experiments indicate that the anatomical information from intra-operative CT-like reconstructions compares favorably with preacquired imaging data and can be of sufficient quality for intra-operative guidance.

Matrix Extension and Multilaboratory Validation of Arsenic Speciation Method EAM §4.10 to Include Wine.

PubMed

Tanabe, Courtney K; Hopfer, Helene; Ebeler, Susan E; Nelson, Jenny; Conklin, Sean D; Kubachka, Kevin M; Wilson, Robert A

2017-05-24

A multilaboratory validation (MLV) was performed to extend the U.S. Food and Drug Administration's (FDA) analytical method Elemental Analysis Manual (EAM) §4.10, High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination of Four Arsenic Species in Fruit Juice, to include wine. Several method modifications were examined to optimize the method for the analysis of dimethylarsinic acid, monomethylarsonic acid, arsenate (AsV), and arsenite (AsIII) in various wine matrices with a range of ethanol concentrations by liquid chromatography-inductively coupled plasma-mass spectrometry. The optimized method was used for the analysis of five wines of different classifications (red, white, sparkling, rosé, and fortified) by three laboratories. Additionally, the samples were fortified in duplicate at levels of approximately 5, 10, and 30 μg kg -1 and analyzed by each participating laboratory. The combined average fortification recoveries of dimethylarsinic acid, monomethylarsonic acid, and inorganic arsenic (iAs the sum of AsV and AsIII) in these samples were 101, 100, and 100%, respectively. To further demonstrate the method, 46 additional wine samples were analyzed. The total As levels of all the wines analyzed in this study were between 1.0 and 38.2 μg kg -1 . The overall average mass balance based on the sum of the species recovered from the chromatographic separation compared to the total As measured was 89% with a range of 51-135%. In the 51 analyzed samples, iAs accounted for an average of 91% of the sum of the species with a range of 37-100%.

Cannabidiol limits Tcell-mediated chronic autoimmune myocarditis: implications to autoimmune disorders and organ transplantation.

PubMed

Lee, Wen-Shin; Erdelyi, Katalin; Matyas, Csaba; Mukhopadhyay, Partha; Varga, Zoltan V; Liaudet, Lucas; Haskó, György; Čiháková, Daniela; Mechoulam, Raphael; Pacher, Pal

2016-01-08

Myocarditis is a major cause of heart failure and sudden cardiac death in young adults and adolescents. Many cases of myocarditis are associated with autoimmune processes in which cardiac myosin is a major autoantigen. Conventional immunosuppressive therapies often provide unsatisfactory results and are associated with adverse toxicities during the treatment of autoimmune myocarditis. Cannabidiol (CBD) is a non-psychoactive constituent of Marijuana which exerts antiinflammatory effects independent from classical cannabinoid receptors. Recently 80 clinical trials have been reported investigating the effects of CBD in various diseases from inflammatory bowel disease to graft-versus-host disease. CBD-based formulations are used for the management of multiple sclerosis in numerous countries, and CBD also received FDA approval for the treatment of refractory childhood epilepsy and glioblastoma multiforme. Herein, using a well-established mouse model of experimental autoimmune myocarditis (EAM) induced by immunization with cardiac myosin emmulsified in adjuvant resulting in T cell-mediated inflammation, cardiomyocyte cell death, fibrosis and myocardial dysfunction, we studied the potential beneficial effects of CBD. EAM was characterized by marked myocardial T cell-infiltration, profound inflammatory response, fibrosis (measured by qRT-PCR, histology and immunohistochemistry analyses) accompanied by marked attenuation of both systolic and diastolic cardiac functions measured with pressure-volume conductance catheter technique. Chronic treatment with CBD largely attenuated the CD3+ and CD4+ mediated inflammatory response and injury, myocardial fibrosis and cardiac dysfunction in mice. CBD may represent a promising novel treatment for management of autoimmune myocarditis and possibly other autoimmune disorders, and organ transplantation.

Cannabidiol Limits T Cell–Mediated Chronic Autoimmune Myocarditis: Implications to Autoimmune Disorders and Organ Transplantation

PubMed Central

Lee, Wen-Shin; Erdelyi, Katalin; Matyas, Csaba; Mukhopadhyay, Partha; Varga, Zoltan V; Liaudet, Lucas; Hask’, György; ’iháková, Daniela; Mechoulam, Raphael; Pacher, Pal

2016-01-01

Myocarditis is a major cause of heart failure and sudden cardiac death in young adults and adolescents. Many cases of myocarditis are associated with autoimmune processes in which cardiac myosin is a major autoantigen. Conventional immunosuppressive therapies often provide unsatisfactory results and are associated with adverse toxicities during the treatment of autoimmune myocarditis. Cannabidiol (CBD) is a nonpsychoactive constituent of marijuana that exerts antiinflammatory effects independent of classical cannabinoid receptors. Recently, 80 clinical trials have investigated the effects of CBD in various diseases from inflammatory bowel disease to graft versus host disease. CBD-based formulations are used for the management of multiple sclerosis in numerous countries, and CBD also received U.S. Food and Drug Administration approval for the treatment of refractory childhood epilepsy and glioblastoma multiforme. Herein, using a well-established mouse model of experimental autoimmune myocarditis (EAM) induced by immunization with cardiac myosin emmulsified in adjuvant resulting in T cell–mediated inflammation, cardiomyocyte cell death, fibrosis and myocardial dysfunction, we studied the potential beneficial effects of CBD. EAM was characterized by marked myocardial T-cell infiltration, profound inflammatory response and fibrosis (measured by quantitative real-time polymerase chain reaction, histology and immunohistochemistry analyses) accompanied by marked attenuation of both systolic and diastolic cardiac functions measured with a pressure-volume conductance catheter technique. Chronic treatment with CBD largely attenuated the CD3+ and CD4+ T cell–mediated inflammatory response and injury, myocardial fibrosis and cardiac dysfunction in mice. In conclusion, CBD may represent a promising novel treatment for managing autoimmune myocarditis and possibly other autoimmune disorders and organ transplantation. PMID:26772776

Are high flow nasal cannulae noisier than bubble CPAP for preterm infants?

PubMed

Roberts, C T; Dawson, J A; Alquoka, E; Carew, P J; Donath, S M; Davis, P G; Manley, B J

2014-07-01

Noise exposure in the neonatal intensive care unit is believed to be a risk factor for hearing loss in preterm neonates. Continuous positive airway pressure (CPAP) devices exceed recommended noise levels. High flow nasal cannulae (HFNC) are an increasingly popular alternative to CPAP for treating preterm infants, but there are no in vivo studies assessing noise production by HFNC. To study whether HFNC are noisier than bubble CPAP (BCPAP) for preterm infants. An observational study of preterm infants receiving HFNC or BCPAP. Noise levels within the external auditory meatus (EAM) were measured using a microphone probe tube connected to a calibrated digital dosimeter. Noise was measured across a range of frequencies and reported as decibels A-weighted (dBA). A total of 21 HFNC and 13 BCPAP noise measurements were performed in 21 infants. HFNC gas flows were 2-5 L/min, and BCPAP gas flows were 6-10 L/min with set pressures of 5-7 cm of water. There was no evidence of a difference in average noise levels measured at the EAM: mean difference (95% CI) of -1.6 (-4.0 to 0.9) dBA for HFNC compared to BCPAP. At low frequency (500 Hz), HFNC was mean (95% CI) 3.0 (0.3 to 5.7) dBA quieter than BCPAP. Noise increased with increasing BCPAP gas flow (p=0.007), but not with increasing set pressure. There was a trend to noise increasing with increasing HFNC gas flows. At the gas flows studied, HFNC are not noisier than BCPAP for preterm infants.

Reliability and validity of tongue color analysis in the prediction of symptom patterns in terms of East Asian Medicine.

PubMed

Park, Young-Jae; Lee, Jin-Moo; Yoo, Seung-Yeon; Park, Young-Bae

2016-04-01

To examine whether color parameters of tongue inspection (TI) using a digital camera was reliable and valid, and to examine which color parameters serve as predictors of symptom patterns in terms of East Asian medicine (EAM). Two hundred female subjects' tongue substances were photographed by a mega-pixel digital camera. Together with the photographs, the subjects were asked to complete Yin deficiency, Phlegm pattern, and Cold-Heat pattern questionnaires. Using three sets of digital imaging software, each digital image was exposure- and white balance-corrected, and finally L* (luminance), a* (red-green balance), and b* (yellow-blue balance) values of the tongues were calculated. To examine intra- and inter-rater reliabilities and criterion validity of the color analysis method, three raters were asked to calculate color parameters for 20 digital image samples. Finally, four hierarchical regression models were formed. Color parameters showed good or excellent reliability (0.627-0.887 for intra-class correlation coefficients) and significant criterion validity (0.523-0.718 for Spearman's correlation). In the hierarchical regression models, age was a significant predictor of Yin deficiency (β = 0.192), and b* value of the tip of the tongue was a determinant predictor of Yin deficiency, Phlegm, and Heat patterns (β = - 0.212, - 0.172, and - 0.163). Luminance (L*) was predictive of Yin deficiency (β = -0.172) and Cold (β = 0.173) pattern. Our results suggest that color analysis of the tongue using the L*a*b* system is reliable and valid, and that color parameters partially serve as symptom pattern predictors in EAM practice.

Embedded-atom-method study of structural, thermodynamic, and atomic-transport properties of liquid Ni-Al alloys

NASA Astrophysics Data System (ADS)

Asta, Mark; Morgan, Dane; Hoyt, J. J.; Sadigh, Babak; Althoff, J. D.; de Fontaine, D.; Foiles, S. M.

1999-06-01

Structural, thermodynamic, and atomic-transport properties of liquid Ni-Al alloys have been studied by Monte Carlo and molecular-dynamics simulations based upon three different embedded-atom method (EAM) interatomic potentials, namely those due to Foiles and Daw (FD) [J. Mater. Res. 2, 5 (1987)], Voter and Chen (VC) [in Characterization of Defects in Materials, edited by R. W. Siegel et al. MRS Symposia Proceedings. No. 82 (Materials Research Society, Pittsburgh, 1987), p.175] and Ludwig and Gumbsch (LG) [Model. Simul. Mater. Sci. Eng. 3, 533 (1995)]. We present detailed comparisons between calculated results and experimental data for structure factors, atomic volumes, enthalpies of mixing, activities, and viscosities. Calculated partial structure factors are found to be in semiquantitative agreement with published neutron scattering measurements for Ni20Al80 alloys, indicating that short-range order in the liquid phase is qualitatively well described. Calculated thermodynamic properties of mixing are found to agree very well with experimental data for Ni compositions greater than 75 atomic %, while for alloys richer in Al the magnitudes of the enthalpies and entropies of mixing are significantly underestimated. The VC and LG potentials give atomic densities and viscosities in good agreement with experiment for Ni-rich compositions, while FD potentials consistently underestimate both properties at all concentrations. The results of this study demonstrate that VC and LG potentials provide a realistic description of the thermodynamic and atomic transport properties for NixAl1-x liquid alloys with x>=0.75, and point to the limitations of EAM potentials for alloys richer in Al.

Molecular Dynamics Modeling of Thermal Properties of Aluminum Near Melting Line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karavaev, A. V.; Dremov, V. V.; Sapozhnikov, F. A.

2006-08-03

In this work we present results of calculations of thermal properties of solid and liquid phases of aluminum at different densities and temperatures using classical molecular dynamics with EAM potential function. Dependencies of heat capacity CV on temperature and density have been analyzed. It was shown that when temperature increases, heat capacity CV behavior deviates from that by Dulong-Petit law. It may be explained by influence of anharmonicity of crystal lattice vibrations. Comparison of heat capacity CV of liquid phase with Grover's model has been performed. Dependency of aluminum melting temperature on pressure has been acquired.

Lightweight Disk Alloy Development

DTIC Science & Technology

1991-04-01

11 (tested parallel to the 540 (1000) 759 (110) 36 extrusi ) n direction) 760 (1400) 348 (51) 113 870 (1600) 143 (21) N /A Ni-29 Al-21 Co 20 (68) 754...security considerations, contractual obligations, or notice on a specific document. sEamTy F SF I& RISM m1Ya ICCUR * rm n n ARNMM 2L SQIXM AUD~M IOm a...061on ~iJIOF REPM~ IAFFWJ 2tp.- C IF n a ’ lS#)MSC 4. PEWORMIMG AM&ATINRMM &. MOPE1IIG 3.... -100 REPORT NI5MRIS FR21413 WDC-TR-S0-4125 Es. NAME( OF EIvkG

Combat Aircraft Noise held in Bonn, Germany on 23-25 October 1991 (Le Bruit Genere par les Avions de Combat)

DTIC Science & Technology

1992-04-01

study suggeet that the penalty in needed Important factors see"m to be the onset but it may be neceesary to extend the rate of the flyovers. In aerieas...the average will underestimate the impcat at laboratOry studies the onset and decay those operations. These two factors . rates have the eams level at...events st a SEL of 115 studies and found that fundamentally all dO gives an Leq(8h) of 88 d8 while Oil tended to support a 10 LagioN event factor events

Angular Vibration of Aircraft. Volume 2. Prediction Methods for Angular Vibration

DTIC Science & Technology

1979-04-01

LNOU=BEAM(L+2pK) IF (LNOD.NE,I) GO 10 160 CALL RLADMS(IN, BMAT ,17*17liFX(bEAM(1𔃿K))+NSHLTY) 336 UU ibU LL=Itb LLL=10M(LLoL) II (LLL,LU,U) Gj IU 150 uu...14u M=IP3 uu 130 MM:I,b MMM=IbM(MM,M) IF (MMM.LQ.O) GO I0 130 MNOU=bLAM(M+2pK) IBIG=bA(MNUD-I)+MM bIG(181G,LL)=blG(ibIG,LL)+ bMAT (LLLiMMM) 13U CUNTINUE

Loess as an environmental archive of atmospheric trace element deposition

NASA Astrophysics Data System (ADS)

Blazina, T.; Winkel, L. H.

2013-12-01

Environmental archives such as ice cores, lake sediment cores, and peat cores have been used extensively to reconstruct past atmospheric deposition of trace elements. These records have provided information about how anthropogenic activities such as mining and fossil fuel combustion have disturbed the natural cycles of various atmospherically transported trace elements (e.g. Pb, Hg and Se). While these records are invaluable for tracing human impacts on such trace elements, they often provide limited information about the long term natural cycles of these elements. An assumption of these records is that the observed variations in trace element input, prior to any assumed anthropogenic perturbations, represent the full range of natural variations. However, records such as those mentioned above which extend back to a maximum of ~400kyr may not capture the potentially large variations of trace element input occurring over millions of years. Windblown loess sediments, often representing atmospheric deposition over time scales >1Ma, are the most widely distributed terrestrial sediments on Earth. These deposits have been used extensively to reconstruct continental climate variability throughout the Quaternary and late Neogene periods. In addition to being a valuable record of continental climate change, loess deposits may represent a long term environmental archive of atmospheric trace element deposition and may be combined with paleoclimate records to elucidate how fluctuations in climate have impacted the natural cycle of such elements. Our research uses the loess-paleosol deposits on the Chinese Loess Plateau (CLP) to quantify how atmospheric deposition of trace elements has fluctuated in central China over the past 6.8Ma. The CLP has been used extensively to reconstruct past changes of East Asian monsoon system (EAM). We present a suite of trace element concentration records (e.g. Pb, Hg, and Se) from the CLP which exemplifies how loess deposits can be used as an environmental archive to reconstruct long term natural variations in atmospheric trace element input. By comparing paleomonsoon proxy data with geochemical data we can directly correlate variations in atmospheric trace element input to fluctuations in the EAM. For example we are able to link Se input into the CLP to EAM derived precipitation. In interglacial climatic periods from 2.3-1.56Ma and 1.50-1.29Ma, we find very strong positive correlations between Se concentration and the summer monsoon index, a proxy for effective precipitation. In later interglacial periods from 1.26-0.83Ma and 0.78-0.16Ma, we find dust input plays a greater role. Our findings demonstrate that the CLP is a valuable environmental archive of atmospheric trace element deposition and suggest that other loess deposits worldwide may serve as useful records for investigating long term natural variations in atmospheric trace element cycling.

Defect energetics of concentrated solid-solution alloys from ab initio calculations: Ni 0.5Co 0.5, Ni 0.5Fe 0.5, Ni 0.8Fe 0.2 and Ni 0.8Cr 0.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Shijun; Stocks, George Malcolm; Zhang, Yanwen

2016-08-03

It has been shown that concentrated solid solution alloys possess unusual electronic, magnetic, transport, mechanical and radiation-resistant properties that are directly related to underlying chemical complexity. Because every atom experiences a different local atomic environment, the formation and migration energies of vacancies and interstitials in these alloys exhibit a distribution, rather than a single value as in a pure metal or dilute alloy. In this study, using ab initio calculations based on density functional theory and special quasirandom structure, we have characterized the distribution of defect formation energy and migration barrier in four Ni-based solid-solution alloys: Ni 0.5Co 0.5, Nimore » 0.5Fe 0.5, Ni 0.8Fe 0.2 and Ni 0.8Cr 0.2. As defect formation energies in finite-size models depend sensitively on the elemental chemical potential, we have developed a computationally efficient method for determining it which takes into account the global composition and the local short-range order. In addition we have compared the results of our ab initio calculations to those obtained from available embedded atom method (EAM) potentials. Our results indicate that the defect formation and migration energies are closely related to the specific atomic size in the structure, which further determines the elemental diffusion properties. In conclusion, different EAM potentials yield different features of defect energetics in concentrated alloys, pointing to the need for additional potential development efforts in order to allow spatial and temporal scale-up of defect and simulations, beyond those accessible to ab initio methods.« less

Association of complement factor B allotypes and serum biomarkers in rheumatoid arthritis patients and their relatives.

PubMed

Nass, F R; Skare, T L; Goeldner, I; Nisihara, R; Messias-Reason, I J; Utiyama, S R R

2015-12-01

The aim of the study was to investigate the allotypic variability of complement factor B (BF) in patients and relatives with rheumatoid arthritis (RA) and its association with serological biomarkers and clinical features of the disease. BF allotypes were determined by high-voltage agarose gel electrophoresis in serum samples of 180 patients with RA, 198 relatives and 98 controls from Southern Brazil. Anticyclic citrullinated peptide (anti-CCP), antimutated citrullinated vimentin (anti-MCV) and IgA-rheumatoid factor (RF) were determined by ELISA and IgM-RF by latex agglutination in all samples. No significant differences were found in the allotypic variants of BF between patients with RA, relatives and controls, nor associations with gender and age of RA onset. BF*S07 allotype was significantly associated with extra-articular manifestations (EAMs; Secondary Sjögren Syndrome, pneumonitis, rheumatoid nodules) in patients with RA (P = 0.02; OR = 6.62). Patients with phenotype BF F had lower positivity for anti-MCV biomarker (P = 0.02; OR = 0.22) and those with allotype BF*S had higher prevalence of this autoantibody (P = 0.02; OR = 3.77). An increased frequency of RF-IgA was detected in relatives of patients with RA with BF FS07 phenotype (P = 0.02; OR = 7.78). Complement BF variability did not influence the development of RA in the studied patients, but BF variants may act as markers of disease prognosis, such as development of EAMs, corroborating with the role of the alternative pathway in the pathogenesis of RA. © 2015 John Wiley & Sons Ltd.

Defect energetics of concentrated solid-solution alloys from ab initio calculations: Ni0.5Co0.5, Ni0.5Fe0.5, Ni0.8Fe0.2 and Ni0.8Cr0.2.

PubMed

Zhao, Shijun; Stocks, G Malcolm; Zhang, Yanwen

2016-09-14

It has been shown that concentrated solid solution alloys possess unusual electronic, magnetic, transport, mechanical and radiation-resistant properties that are directly related to underlying chemical complexity. Because every atom experiences a different local atomic environment, the formation and migration energies of vacancies and interstitials in these alloys exhibit a distribution, rather than a single value as in a pure metal or dilute alloy. Using ab initio calculations based on density functional theory and special quasirandom structures, we have characterized the distribution of defect formation energy and migration barrier in four Ni-based solid-solution alloys: Ni0.5Co0.5, Ni0.5Fe0.5, Ni0.8Fe0.2, and Ni0.8Cr0.2. As defect formation energies in finite-size models depend sensitively on the elemental chemical potential, we have developed a computationally efficient method for determining it which takes into account the global composition and the local short-range order. In addition we have compared the results of our ab initio calculations to those obtained from available embedded atom method (EAM) potentials. Our results indicate that the defect formation and migration energies are closely related to the specific atoms in the structure, which further determines the elemental diffusion properties. Different EAM potentials yield different features of defect energetics in concentrated alloys, pointing to the need for additional potential development efforts in order to allow spatial and temporal scale-up of defect and simulations, beyond those accessible to ab initio methods.

Sea-surface temperatures for the last 7200 years from the eastern Sunda Shelf, South China Sea: Climatic inferences from planktonic foraminiferal Mg/Ca ratios

NASA Astrophysics Data System (ADS)

Woodson, Anna Lee; Leorri, Eduardo; Culver, Stephen J.; Mallinson, David J.; Parham, Peter R.; Thunell, Robert C.; Vijayan, V. R.; Curtis, Scott

2017-06-01

To test whether low latitude shallow shelf deposits can provide high resolution paleoclimatic records, we utilized two cores from the Holocene sedimentary fill of incised valleys on the Sunda Shelf off Sarawak, Malaysia. We developed a new sea-surface temperature (SST) record based on planktonic foraminiferal Mg/Ca for the last 7200 years. This record reveals several significant shifts between warmer and colder conditions. Temperatures averaged 27.5 °C ca. 7200 cal. years BP, then climbed to 28.2 °C from 6500 to 5500 cal. years BP. At 5500-4500 cal. years BP we identified the coldest period (26.8 °C) of the analyzed period. For the last 4500 years SST again averaged 27.5 °C but the profile is rather variable. The last ca. 1000 years recorded the warmest SST averaging 28.5 °C. We record, for the first time in this region, a cool interval, ca. 1000 years in duration, centered on 5000 cal years BP concomitant with a wet period recorded in Borneo. The record also reflects a warm interval from ca. 1000 to 500 cal years BP that may represent the Medieval Climate Anomaly. Variations in the East Asian Monsoon (EAM) and solar activity are considered as potential drivers of SST trends. However, hydrology changes related to the El Niño-Southern Oscillation (ENSO) variability, shifts of the Western Pacific Warm Pool and migration of the Intertropical Convergence Zone are more likely to have impacted our SST temporal trend. Our findings indicate that climatic patterns in the region might be in phase with ENSO and out of phase with the EAM.

Different regions of latest electrical activation during left bundle-branch block and right ventricular pacing in cardiac resynchronization therapy patients determined by coronary venous electro-anatomic mapping.

PubMed

Mafi Rad, Masih; Blaauw, Yuri; Dinh, Trang; Pison, Laurent; Crijns, Harry J; Prinzen, Frits W; Vernooy, Kevin

2014-11-01

Current targeted left ventricular (LV) lead placement strategy is directed at the latest activated region during intrinsic activation. However, cardiac resynchronization therapy (CRT) is most commonly applied by simultaneous LV and right ventricular (RV) pacing without contribution from intrinsic conduction. Therefore, targeting the LV lead to the latest activated region during RV pacing might be more appropriate. We investigated the difference in LV electrical activation sequence between left bundle-branch block (LBBB) and RV apex (RVA) pacing using coronary venous electro-anatomic mapping (EAM). Twenty consecutive CRT candidates with LBBB underwent intra-procedural coronary venous EAM during intrinsic activation and RVA pacing using EnSite NavX. Left ventricular lead placement was aimed at the latest activated region during LBBB according to current recommendations. In all patients, LBBB was associated with a circumferential LV activation pattern, whereas RVA pacing resulted in activation from the apex of the heart to the base. In 10 of 20 patients, RVA pacing shifted the latest activated region relative to LBBB. In 18 of 20 patients, the LV lead was successfully positioned in the latest activated region during LBBB. For the whole study population, LV lead electrical delay, expressed as percentage of QRS duration, was significantly shorter during RVA pacing than during LBBB (72 ± 13 vs. 82 ± 5%, P = 0.035). Right ventricular apex pacing alters LV electrical activation pattern in CRT patients with LBBB, and shifts the latest activated region in a significant proportion of these patients. These findings warrant reconsideration of the current practice of LV lead targeting for CRT. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

Donor exciton of cobalt and its interaction with lattice vibrations in the semiconductor crystal ZnO:Co

NASA Astrophysics Data System (ADS)

Gruzdev, N. B.; Sokolov, V. I.; Yemelchenko, G. A.

2009-01-01

Vibrational states interacting with a donor exciton in the compound ZnO:Co are revealed by the sensitive method of field exciton-vibrational spectroscopy. The vibrational modes of the electroabsorption spectrum of the compound ZnO:Co in the region of the donor exciton are given an interpretation based on the existing data on the symmetrized local density of states of the compounds ZnO and ZnO :Ni3+. The results are compared with the known data for II-VI:Ni compounds in the case of an acceptor exciton. The position of the donor level of the Co2+ ion relative to the bottom of the conduction band in the given compound is determined and found to conform well to the universal trend for donor levels of 3d ions in II-VI compounds.

Coast to Coast Support of the E-2C Hawkeye using Distributed TSP

DTIC Science & Technology

2008-05-02

Share history of each subgroup and establish a vision f th f t f thi l f d to e u ure or s new y orme eam 3. Establish team operating principles...visits were made by team t th ld k t b d b ild th b id b t th Th ff t NAVAIR Systems/Software Support Center (NSSC) Slide 18 managemen so ey cou now...Success • High quality products from multiple teams delivered on ti d t d tme an cos o no happen in a vacuum • There is a need for common processes

Computer simulation of liquid metals

NASA Astrophysics Data System (ADS)

Belashchenko, D. K.

2013-12-01

Methods for and the results of the computer simulation of liquid metals are reviewed. Two basic methods, classical molecular dynamics with known interparticle potentials and the ab initio method, are considered. Most attention is given to the simulated results obtained using the embedded atom model (EAM). The thermodynamic, structural, and diffusion properties of liquid metal models under normal and extreme (shock) pressure conditions are considered. Liquid-metal simulated results for the Groups I - IV elements, a number of transition metals, and some binary systems (Fe - C, Fe - S) are examined. Possibilities for the simulation to account for the thermal contribution of delocalized electrons to energy and pressure are considered. Solidification features of supercooled metals are also discussed.

Molecular dynamic simulation for nanometric cutting of single-crystal face-centered cubic metals.

PubMed

Huang, Yanhua; Zong, Wenjun

2014-01-01

In this work, molecular dynamics simulations are performed to investigate the influence of material properties on the nanometric cutting of single crystal copper and aluminum with a diamond cutting tool. The atomic interactions in the two metallic materials are modeled by two sets of embedded atom method (EAM) potential parameters. Simulation results show that although the plastic deformation of the two materials is achieved by dislocation activities, the deformation behavior and related physical phenomena, such as the machining forces, machined surface quality, and chip morphology, are significantly different for different materials. Furthermore, the influence of material properties on the nanometric cutting has a strong dependence on the operating temperature.

Simulation of uniaxial deformation of hexagonal crystals (Mg, Be)

NASA Astrophysics Data System (ADS)

Vlasova, A. M.; Kesarev, A. G.

2017-12-01

Molecular dynamics (MD) simulations were performed for the nanocompression loading of nanocrystalline magnesium and beryllium modeled by an interatomic potential of the embedded atom method (EAM). It is shown that the main deformation modes are prismatic slip and twinning for magnesium, and only prismatic slip for beryllium. The formation of stable configurations of dislocation grids in magnesium and beryllium was observed. Dislocation networks are formed in the habit plane of the twin in a magnesium nanocrystall. Some dislocation reactions are suggested to explain the appearance of such networks. Shockley partial dislocations in a beryllium nanocrystall form grids in the slip plane. A strong anisotropy between slip systems was observed, which is in agreement with experimental data.

Characterizing diurnal and seasonal cycles in monsoon systems from TRMM and CEOP observations

NASA Technical Reports Server (NTRS)

Lau, William K. M.

2006-01-01

The CEOP Inter-Monsoon Study (CIMS) is one of the two main science drivers of CEOP that aims to (a) provide better understanding of fundamental physical processes in monsoon regions around the world, and (b) demonstrate the synergy and utility of CEOP data in providing a pathway for model physics evaluation and improvement. As the data collection phase for EOP-3 and EOP-4 is being completed, two full annual cycles (2003-2004) of research-quality data sets from satellites, reference sites, and model output location time series (MOLTS) have been processed and made available for data analyses and model validation studies. This article presents preliminary results of a CIMS study aimed at the characterization and intercomparison of all major monsoon systems. The CEOP reference site data proved its value in such exercises by being a powerful tool to cross-validate the TRMM data, and to intercompare with multi-model results in ongoing work. We use 6 years (1998-2003) of pentad CEOP/TRMM data with 2deg x 2.5deg latitude-longitude grid, over the domain of interests to define the monsoon climatological diurnal and annual cycles for the East Asian Monsoon (EAM), the South Asian Monsoon (SAM), the West Africa Monsoon (WAM), the North America/Mexican Monsoon (NAM), the South American Summer Monsoon (SASM) and the Australian Monsoon (AUM). As noted, the TRMM data used in the study were cross-validated using CEOP reference site data, where applicable. Results show that the observed diurnal cycle of rain peaked around late afternoon over monsoon land, and early morning over the oceans. The diurnal cycles in models tend to peak 2-3 hours earlier than observed. The seasonal cycles of the EAM and SAM show the strongest continentality, i.e, strong control by continental processes away from the ITCZ. The WAM, and the AUM shows the less continentality, i.e, strong control by the oceanic ITCZ.

Characterizing Diurnal and Seasonal Cycles in Monsoon Systems from TRMM and CEOP Observations

NASA Technical Reports Server (NTRS)

Lau, William K. M.

2007-01-01

The CEOP Inter-Monsoon Study (CIMS) is one of the two main science drivers of CEOP that aims to (a) provide better understanding of fundamental physical processes in monsoon regions around the world, and (b) demonstrate the synergy and utility of CEOP data in providing a pathway for model physics evaluation and improvement. As the data collection phase for EOP-3 and EOP-4 is being completed, two full annual cycles (2003-2004) of research-quality data sets from satellites, reference sites, and model output location time series (MOLTS) have been processed and made available for data analyses and model validation studies. This article presents preliminary results of a CIMS study aimed at the characterization and intercomparison of all major monsoon systems. The CEOP reference site data proved its value in such exercises by being a powerful tool to cross-validate the TRMM data, and to intercompare with multi-model results in ongoing work. We use 6 years (1998-2003) of pentad CEOP/TRMM data with 2 deg x 2.5 deg. latitude-longitude grid, over the domain of interests to define the monsoon climatological diurnal and annual cycles for the East Asian Monsoon (EAM), the South Asian Monsoon (SAM), the West Africa Monsoon (WAM), the North America/Mexican Monsoon (NAM), the South American Summer Monsoon (SASM) and the Australian Monsoon (AUM). As noted, the TRMM data used in the study were cross-validated using CEOP reference site data, where applicable. Results show that the observed diurnal cycle of rain peaked around late afternoon over monsoon land, and early morning over the oceans. The diurnal cycles in models tend to peak 2-3 hours earlier than observed. The seasonal cycles of the EAM and SAM show the strongest continentality, i.e, strong control by continental processes away from the ITCZ. The WAM, and the AUM shows the less continentality, i.e, strong control by the oceanic ITCZ.

Impact of earliest activation site location in the septal right ventricular outflow tract for identification of left vs right outflow tract origin of idiopathic ventricular arrhythmias.

PubMed

Acosta, Juan; Penela, Diego; Herczku, Csaba; Macías, Yolanda; Andreu, David; Fernández-Armenta, Juan; Cipolletta, Laura; Díaz, Andrés; Korshunov, Viatcheslav; Brugada, Josep; Mont, Lluis; Cabrera, Jose A; Sánchez-Quintana, Damián; Berruezo, Antonio

2015-04-01

The earliest activation site (EAS) location in the septal right ventricular outflow tract (RVOT) could be an additional mapping data predictor of left ventricular outflow tract (LVOT) vs RVOT origin of idiopathic ventricular arrhythmias (VAs). The purpose of this study was to assess the impact of EAS location in predicting LVOT vs RVOT origin. Macroscopic and histologic study was performed in 12 postmortem hearts. Electroanatomic maps (EAMs) from 37 patients with outflow tract (OT) VA with the EAS in the septal RVOT were analyzed. Pulmonary valve (PV) was defined by voltage scanning after validation of voltage thresholds by image integration. EAM measurements were correlated with those of macroscopic/histologic study. A cutoff value of 1.9 mV discriminated between subvalvular and supravalvular positions (90% sensitivity, 96% specificity). EAS ≥1 cm below PV excluded RVOT site of origin (SOO). According to anatomic findings (distance PV-left coronary cusp = 5 ± 3 vs PV-right coronary cusp = 11 ± 5 mm), EAS-PV distance was significantly shorter in VAs arising from left coronary cusp than from the other LVOT locations (4.2 ± 5.4 mm vs 9.2 ± 7 mm; P = .034). The 10-ms isochronal longitudinal/perpendicular diameter ratio was higher in the RVOT vs the LVOT SOO group (1.97 ± 1.2 vs 0.79 ± 0.49; P = .001). An algorithm based on EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio predicted LVOT SOO with 91% sensitivity and 100% specificity. An algorithm based on the EAS-PV distance and the 10-ms isochronal longitudinal/perpendicular diameter ratio accurately predicts LVOT vs RVOT SOO in outflow tract VAs with EAS in the septal RVOT. Copyright © 2015 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Late-Holocene vegetation and climate change in Jeju Island, Korea and its implications for ENSO influences

NASA Astrophysics Data System (ADS)

Park, Jungjae; Shin, Young Ho; Byrne, Roger

2016-12-01

Several recent studies suggest the hypothesis that the El Niño-Southern Oscillation (ENSO) is an important factor controlling the Holocene East Asian Monsoon (EAM). However, the mechanism underlying this influence remains unclear due to the lack of high-resolution paleoclimate records from the coast of East Asia. Here, we provide a new record of late Holocene climate change in coastal East Asia based on multi-proxy evidence (pollen, organic content, magnetic susceptibility, grain size) obtained from a sediment core from Jeju Island, South Korea. As Jeju Island is strongly influenced by the Kuroshio flow, our sediment proxy records contain ENSO signals from the tropical Pacific. The study area was affected by dry/cool conditions in the western tropical Pacific (WTP) between 4350 and 1920 cal yr BP when El Niños were frequent, and by rapid warming/wetting and forestation since 1920 cal yr BP when La Niñas were more common. Jeju Island was relatively dry/cool between 2100 and 1600, 1300-1200, 1100-1000, 800-650, and 300-50 cal yr BP, as opposed to the Galápagos Islands, which were relatively wet/warm, reflecting the ENSO-related negative correlation between eastern and western margins of Pacific. Wet conditions may have prevailed during the early Little Ice Age (LIA) (620-280 cal yr BP) despite consistent cooling. This period of high precipitation may have been associated with the increased landfall of typhoons and with warmer Kuroshio currents under La Niña-like conditions. According to our results, EAM on the East Asian coastal margin was predominantly driven by ENSO activity, rather than by the precession effect. Paleoclimatic data from Jeju Island, with its insular position and closeness to warm Kuroshio currents, provide clear evidence of these ENSO influences.

Modeling material interfaces with hybrid adhesion method

DOE PAGES

Brown, Nicholas Taylor; Qu, Jianmin; Martinez, Enrique

2017-01-27

A molecular dynamics simulation approach is presented to approximate layered material structures using discrete interatomic potentials through classical mechanics and the underlying principles of quantum mechanics. This method isolates the energetic contributions of the system into two pure material layers and an interfacial region used to simulate the adhesive properties of the diffused interface. The strength relationship of the adhesion contribution is calculated through small-scale separation calculations and applied to the molecular surfaces through an inter-layer bond criterion. By segregating the contributions into three regions and accounting for the interfacial excess energies through the adhesive surface bonds, it is possiblemore » to model each material with an independent potential while maintaining an acceptable level of accuracy in the calculation of mechanical properties. This method is intended for the atomistic study of the delamination mechanics, typically observed in thin-film applications. Therefore, the work presented in this paper focuses on mechanical tensile behaviors, with observations in the elastic modulus and the delamination failure mode. To introduce the hybrid adhesion method, we apply the approach to an ideal bulk copper sample, where an interface is created by disassociating the force potential in the middle of the structure. Various mechanical behaviors are compared to a standard EAM control model to demonstrate the adequacy of this approach in a simple setting. In addition, we demonstrate the robustness of this approach by applying it on (1) a Cu-Cu 2O interface with interactions between two atom types, and (2) an Al-Cu interface with two dissimilar FCC lattices. These additional examples are verified against EAM and COMB control models to demonstrate the accurate simulation of failure through delamination, and the formation and propagation of dislocations under loads. Finally, the results conclude that by modeling the energy contributions of an interface using hybrid adhesion bonds, we can provide an accurate approximation method for studies of large-scale mechanical properties, as well as the representation of various delamination phenomena at the atomic scale.« less

TLR4-HMGB1 signaling pathway affects the inflammatory reaction of autoimmune myositis by regulating MHC-I.

PubMed

Wan, Zemin; Zhang, Xiujuan; Peng, Anping; He, Min; Lei, Zhenhua; Wang, Yunxiu

2016-12-01

To analyze the effects of TLR4 on the expression of the HMGB1, MHC-I and downstream cytokines IL-6 and TNF-α, and to investigate the biological role of the TLR4-HMGB1 signaling pathway in the development of the autoimmune myositis. We built mice models with experimental autoimmune myositis (EAM) and used the inverted screen experiment to measure their muscle endurance; we also examined inflammatory infiltration of muscle tissues after HE staining; and we assessed the expression of MHC-I using immunohistochemistry. In addition, peripheral blood mononuclear cells (PBMC) were extracted and flow cytometry was utilized to detect the effect of IFN-γ on the expression of MHC-I. Furthermore, PBMCs were treated with IFN-γ, anti-TLR4, anti-HMGB1 and anti-MHC-I. Real-time PCR and western blotting were employed to examine the expressions of TLR4, HMGB1 and MHC-I in different groups. The ELISA method was also utilized to detect the expression of the downstream cytokines TNF-α and IL-6. The expressions of TLR4, HMGB1 and MHC-I in muscle tissues from mice with EAM were significantly higher than those in the control group (all P<0.05). After IFN-γ treatment, the expressions of TLR4, HMGB1, MHC-I, TNF-α and IL-6 in PBMCs significantly increased (all P<0.05). The treatment of anti-TLR4, anti-HMGB1 and anti-MHC-I could significantly downregulate the expression of MHC-I (all P<0.05). In addition, anti-TLR4 and anti-HMGB1 significantly reduced the expression of TNF-α and IL-6 (all P<0.05). The TLR4-HMGB1 signaling pathway affects the process of autoimmune myositis inflammation by regulating the expression of MHC-I and other pro-inflammatory cytokines. Copyright © 2016 Elsevier B.V. All rights reserved.

Design and fabrication of two kind of SOI-based EA-type VOAs

NASA Astrophysics Data System (ADS)

Yuan, Pei; Wang, Yue; Wu, Yuanda; An, Junming; Hu, Xiongwei

2018-06-01

SOI-based variable optical attenuators based on electro-absorption mechanism are demonstrated in this paper. Two different doping structures are adopted to realize the attenuation: a structure with a single lateral p-i-n diode and a structure with several lateral p-i-n diodes connected in series. The VOAs with lateral p-i-n diodes connected in series (series VOA) can greatly improve the device attenuation efficiency compared to VOAs with a single lateral p-i-n diode structure (single VOA), which is verified by the experimental results that the attenuation efficiency of the series VOA and the single VOA is 3.76 dB/mA and 0.189 dB/mA respectively. The corresponding power consumption at 20 dB attenuation is 202 mW (series VOA) and 424 mW (single VOA) respectively. The raise time is 34.5 ns (single VOA) and 45.5 ns (series VOA), and the fall time is 37 ns (single VOA) and 48.5 ns (series VOA).

Quadratic Electro-optic Effect in a Novel Nano-optical Polymer (iodine-doped polyisoprene)

NASA Astrophysics Data System (ADS)

Swamy, Rajendra; Titus, Jitto; Thakur, Mrinal

2004-03-01

In this report, exceptionally large quadratic electro-optic effect in a novel nano-optical polymer will be discussed. The material involved is cis-1,4-polyisoprene or natural rubber which is a nonconjugated conductive polymer[1,2].Upon doping with an acceptor such as iodine, an electron is transferred from its isolated double bond to the dopant leading to a charge-transfer complex. The positive charge (hole) thus created is localized around the double-bond site, within a nanometer dimension - thus, forming a nano-optical material. The quadratic electro-optic measurement on the doped polyisoprene film was made using field-induced birefringence method. The measured Kerr coefficient is about sixty six times that of nitrobenzene at 632 nm. Significant electroabsorption was also observed in this material at 632 nm. 1. M. Thakur, J. Macromol. Sci. - PAC, 2001, A38(12), 1337. 2. M. Thakur, S. Khatavkar and E.J. Parish, J. Macromol. Sci. - PAC, 2003, A40 (12), 1397.

The enemy within us: lessons from the 2011 European Escherichia coli O104:H4 outbreak.

PubMed

Karch, Helge; Denamur, Erick; Dobrindt, Ulrich; Finlay, B Brett; Hengge, Regine; Johannes, Ludgers; Ron, Eliora Z; Tønjum, Tone; Sansonetti, Philippe J; Vicente, Miguel

2012-09-01

In response to the 2011 European health alert caused by a pathogenic Escherichia coli O104:H4 outbreak, the European Academy of Microbiology (EAM), established by the Federation of European Microbiological Societies (FEMS), convened a meeting in Paris on November 30th, 2011 on 'EHEC infection and control' attended by world renowned experts in pathogenic E. coli. The major aims of this group were to review the scientific issues raised by the outbreak, to assess the handling of the crisis at the scientific and political levels, and to propose future actions. Several conclusions, which will have impact on future potential E. coli outbreaks, are outlined here. Copyright © 2012 EMBO Molecular Medicine.

Atomistic study of nanoprecipitates influence on plasticity and fracture of crystalline metals

NASA Astrophysics Data System (ADS)

Stegailov, Vladimir; Kuksin, Alexey; Norman, Genri; Yanilkin, Alexey

2007-06-01

The recent experimental results [G.I.Kanel et al., 2006] show the essential influence of the nanoprecipitates on spall strength of copper single crystals. In this work we address this issue by the molecular dynamics study. The models under consideration are the EAM systems of Al nanoclusters in the Cu matrix and Cu clusters in the Al matrix. We consider these two cases as the representative examples of nanocluster-matrix difference in shear strength. Three ways of the high strain rate deformation modeling are studied: hydrostatic and uniaxial strain and shock wave loading in the impactor-target model. The preexisting edge dislocation interaction with the precipitate under shear deformation is addressed. The effect of the precipitate size is considered.

Atomic-scale Modeling of the Structure and Dynamics of Dislocations in Complex Alloys at High Temperatures

NASA Technical Reports Server (NTRS)

Daw, Murray S.; Mills, Michael J.

2003-01-01

We report on the progress made during the first year of the project. Most of the progress at this point has been on the theoretical and computational side. Here are the highlights: (1) A new code, tailored for high-end desktop computing, now combines modern Accelerated Dynamics (AD) with the well-tested Embedded Atom Method (EAM); (2) The new Accelerated Dynamics allows the study of relatively slow, thermally-activated processes, such as diffusion, which are much too slow for traditional Molecular Dynamics; (3) We have benchmarked the new AD code on a rather simple and well-known process: vacancy diffusion in copper; and (4) We have begun application of the AD code to the diffusion of vacancies in ordered intermetallics.

Autoimmune Myocarditis, Valvulitis, and Cardiomyopathy

PubMed Central

Myers, Jennifer M.; Cunningham, Madeleine W.; Fairweather, DeLisa; Huber, Sally A.

2013-01-01

Cardiac myosin-induced autoimmune myocarditis (EAM) is a model of inflammatory heart disease initiated by CD4+ T cells (Smith and Allen 1991; Li, Heuser et al. 2004). It is a paradigm of the immune-mediated cardiac damage believed to play a role in the pathogenesis of a subset of postinfectious human cardiomyopathies (Rose, Herskowitz et al. 1993). Myocarditis is induced in susceptible mice by immunization with purified cardiac myosin (Neu, Rose et al. 1987) or specific peptides derived from cardiac myosin (Donermeyer, Beisel et al. 1995; Pummerer, Luze et al. 1996) (see Basic Protocol 1), or by adoptive transfer of myosin-reactive T cells (Smith and Allen 1991) (see Alternate Protocol). Myocarditis has been induced in Lewis rats by immunization with purified rat or porcine cardiac myosin (Kodama, Matsumoto et al. 1990; Li, Heuser et al. 2004) (see Basic Protocol 2) or S2-16 peptide (Li, Heuser et al. 2004), or by adoptive transfer of T cells stimulated by specific peptides derived from cardiac myosin (Wegmann, Zhao et al. 1994). Myocarditis begins 12 to 14 days after the first immunization, and is maximal after 21 days. Other animal models commonly used to study myocarditis development include the pathogen-induced models in which disease is initiated by viral infection. The first murine model of acute viral myocarditis causes sudden death via viral damage to cardiomyocytes (Huber, Gauntt et al. 1998; Horwitz, La Cava et al. 2000; Fong 2003; Fuse, Chan et al. 2005; Fairweather and Rose 2007; Cihakova and Rose 2008) whereas the second model is based on inoculation with heart-passaged coxsackievirus B3 (CVB3) that includes damaged heart proteins (Fairweather, Frisancho-Kiss et al. 2004; Fairweather D 2004; Fairweather and Rose 2007; Cihakova and Rose 2008) In addition to the protocols used to induce EAM in mice and rats, support protocols are included for preparing purified cardiac myosin using mouse or rat heart tissue (see Support Protocol 1), preparing purified cardiac myosin for injection (see Support Protocol 2), and collecting and assessing hearts by histopathological means (see Support Protocol 3). PMID:23564686

A major change in precipitation gradient on the Chinese Loess Plateau at the Pliocene-Quaternary boundary

NASA Astrophysics Data System (ADS)

Peng, Wenbin; Nie, Junsheng; Wang, Zhao; Qiang, Xiaoke; Garzanti, Eduardo; Pfaff, Katharina; Song, Yougui; Stevens, Thomas

2018-04-01

Spatiotemporal variations in East Asian Monsoon (EAM) precipitation during the Quaternary have been intensively studied. However, spatial variations in pre-Quaternary EAM precipitation remain largely uninvestigated, preventing a clear understanding of monsoon dynamics during a warmer climatic period. Here we compare the spatial differences in heavy mineral assemblages between Quaternary loess and pre-Quaternary Red Clay on the Chinese Loess Plateau (CLP) to analyze spatial patterns in weathering. Prior studies have revealed that unstable hornblende is the dominant (∼50%) heavy mineral in Chinese loess deposited over the past 500 ka, whereas hornblende content decreases to <10% in strata older than ∼1 Ma in the central CLP because of diagenesis. In the present study we found that hornblende is the dominant heavy mineral in 2-2.7 Ma loess on the northeastern CLP (at Jiaxian), which today receives little precipitation. Conversely, hornblende content in the upper Miocene-Pliocene Red Clay at Jiaxian is <10%, as in the central CLP. The early Quaternary abundance of hornblende at Jiaxian indicates that the current northwestward-decreasing precipitation pattern and consequent dry climate at Jiaxian must have been initiated since ∼2.7 Ma, preventing hornblende dissolution to amounts <10% as observed in the central CLP. By contrast, the 7 Ma and 3 Ma Jiaxian Red Clay hornblende content is significantly less than that of the Xifeng samples, despite the fact that today Xifeng receives more precipitation than Jiaxian, with expected enhanced hornblende weathering. This suggests that the northeastern CLP received more precipitation during the Late Miocene-Pliocene than at Xifeng, indicating that the precipitation gradient on the CLP was more east-west during the Late Miocene-Pliocene rather than northwest-southeast as it was in the Quaternary. A comparison of magnetic susceptibility records for these sections confirms this inference. We attribute this major change in climatic patterns at ∼2.7 Ma to decreased northward moisture transportation associated with Northern Hemisphere glaciation and cooling in the Quaternary. This study therefore demonstrates the potential usefulness of employing heavy mineral analysis in both paleoclimatic and paleooceanographic reconstructions.

MicroRNA-381 reduces inflammation and infiltration of macrophages in polymyositis via downregulating HMGB1.

PubMed

Liu, Yutao; Gao, Yuan; Yang, Jing; Shi, Changhe; Wang, Yanlin; Xu, Yuming

2018-06-29

The downregulation of microRNA (miR)-381 has been detected in various diseases. The present study aimed to investigate the effects, and underlying mechanisms of miR-381 on inflammation and macrophage infiltration in polymyositis (PM). A mouse model of experimental autoimmune myositis (EAM) was generated in this study. Hematoxylin and eosin staining was conducted to detect the inflammation of muscle tissues. In addition, ELISA and immunohistochemistry were performed to determine the expression levels of associated factors, and reverse transcription-quantitative polymerase chain reaction and western blotting were used to detect the expression levels of related mRNAs and proteins. A luciferase activity assay was used to confirm the binding of miR-381 and high mobility group box 1 (HMGB1) 3' untranslated region. Transwell assays were also performed to assess the migratory ability of macrophages. The results demonstrated that serum creatine kinase (s-CK), HMGB1 and cluster of differentiation (CD)163 expression in patients with PM were increased compared within healthy controls. Conversely, the expression levels of miR-381 were downregulated in patients with PM. Furthermore, high HMGB1 expression was associated with poor survival rate in patients with PM. In the mouse studies, muscle inflammation and CD163 expression were decreased in the anti-IL-17 and anti-HMGB1 groups, compared with in the EAM model group. The expression levels of s-CK, HMGB1, IL-17 and intercellular adhesion molecule (ICAM)-1 were also downregulated in response to anti-IL-17 and anti-HMGB1. These findings indicated that HMGB1 was closely associated with inflammatory responses. In addition, the present study indicated that transfection of macrophages with miR-381 mimics reduced the migration of inflammatory macrophages, and the expression levels of HMGB1, IL-17 and ICAM-1. Conversely, miR-381 inhibition exerted the opposite effects. The effects of miR-381 inhibitors were reversed by HMGB1 small interfering RNA. In conclusion, miR-381 may reduce inflammation and the infiltration of macrophages; these effects were closely associated with the downregulation of HMGB1.

Nonlinear absorption properties of AlGaAs/GaAs multiple quantum wells grown by metalorganic chemical vapor deposition

NASA Technical Reports Server (NTRS)

Lee, Hsing-Chung; Kost, A.; Kawase, M.; Hariz, A.; Dapkus, P. Daniel

1988-01-01

The nonlinear absorption properties of the excitonic resonances associated with multiple quantum wells (MQWs) in AlGaAs/GaAs grown by metalorganic chemical vapor deposition are reported. The dependence of the saturation properties on growth parameters, especially growth temperature, and the well width are described. The minimum measured saturation intensity for these materials is 250 W/sq cm, the lowest reported value to date. The low saturation intensities are the result of excellent minority carrier properties. A systematic study of minority carrier lifetimes in quantum wells are reported. Lifetimes range from 50-350 ns depending on growth temperature and well width. When corrected for lateral diffusion effects and the measured minority carrier lifetime, the saturation data suggest that saturation intensities as low as 2.3 W/sq cm can be achieved in this system. The first measurements of the dependence of the exciton area and the magnitude of the excitonic absorption on well width are prsented. The growth of MQW structures on transparent GaP substrates is demonstrated and the electroabsorption properties of these structures are reviewed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

Exciton self-trapping and Stark effect in the optical response of pentacene crystals from first principles

NASA Astrophysics Data System (ADS)

Strubbe, David A.; Sharifzadeh, Sahar; Neaton, Jeffrey B.; Louie, Steven G.

2012-02-01

Pentacene is a prototypical organic semiconductor with optoelectronic and photovoltaic applications. It is known that the lowest-energy singlet excitation has a Stokes shift between absorption and emission of about 0.14 eV, but the deformation associated with this self-trapped exciton remains unknown. We begin with a calculation of the optical properties via the first-principles GW/Bethe-Salpeter (BSE) theory [ML Tiago, JE Northrup, and SG Louie, Phys. Rev. B 67, 115212 (2003); S Sharifzadeh, A Biller, L Kronik, and JB Neaton, arXiv:1110.4928 (2011)]. We then study the self-trapping phenomenon via our reformulation of the Bethe-Salpeter excited-state forces approximation of Ismail-Beigi and Louie [Phys. Rev. Lett. 90, 076401 (2003)], which can describe the structural relaxation after optical excitation. Whether excitons in pentacene have charge-transfer character has been controversial in electro-absorption experiments. We use the same BSE analytic derivatives approach to calculate the changes in excitation energies due to an applied electric field to understand this experimental controversy.

Measurement of Effective Drift Velocities of Electrons and Holes in Shallow Multiple Quantum Well P-I Modulators

NASA Astrophysics Data System (ADS)

Yang, Ching-Mei

1995-01-01

P-i-n diodes containing multiple quantum wells (MQWs) in the i-region are the building blocks for photonic devices. When we apply electric field across these devices and illuminate it with light, photo-carriers are created in the i-region. These carriers escape from the wells and drift toward the electrodes; thus photo-voltage is created. The rise- and decay-times of photo-voltages are related to the transport of carriers. In this dissertation, we present theoretical and experimental studies on carrier transport mechanisms of three shallow MQW GaAs/Al _{x}Ga_{1-x}As p-i-n diodes (x = 0.02, 0.04, 0.08) at various bias voltages. We start with the description of the sample structures and their package. We then present the characteristics of these samples including their transmission spectra and responsivity. We will demonstrate that the over-all high quality of these samples, including a strong exciton resonant absorption, ~100% internal quantum efficiencies and completely depleted i-region at bias between +0.75 V to -5 V bias. In our theoretical studies, we first discuss the possible carrier sweep-out mechanisms and estimate the response times associated with these mechanisms. Based on our theoretical model, we conclude that only the drift times of carriers and enhanced diffusion times are important for shallow MQW p-i-n diodes: at high bias, the fast drift times of electrons and holes control the rise-times; at low bias, the slow drift times of holes and the enhanced diffusion times control the decay-times. We have performed picosecond time-resolved pump/probe electro-absorption measurements on these samples. We then obtained the drift times, effective drift velocities and effective mobilities of electrons and holes for these devices. We find that the carrier effective drift velocities (especially for holes) seemed insensitive to the Al concentration in the barriers (in the range of x = 2% to 8%), even though the x = 2% sample does show an overall faster response time. We think the slight difference of the rise- and decay-times of these devices may also be affected by random differences between the samples.

Pressure effect on phonon frequencies in some transition metals: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Kazanc, S.; Ozgen, S.

2005-08-01

It is important to determine the atomic lattice vibrations of metallic materials, under high-pressure conditions, due to its effects on material properties such as thermal, electrical and optical conductions. In this work, we have investigated the changes of acoustic phonon frequencies with hydrostatic pressure for Cu, Ni, Al, Ag and Au transition metals, using molecular dynamics (MD) simulations based on embedded atom method (EAM). For this aim, we have adopted the embedded atom potential proposed by Sutton and Chen. The phonon frequencies have been calculated from the dynamical matrix for [1 0 0], [1 1 0] and [1 1 1] high symmetry directions of the Brillouin zone. The obtained results show that the hydrostatic pressure causes an increment in phonon frequencies, and this rising do not depend linearly on the increasing pressure.

Facsimile: An Overview for the Manager. Executive Summary.

DTIC Science & Technology

1973-05-01

block nia,b.r) SEE ATTACHED SHEET N~ A~~~~~AC? f’ ~~~ Id~~ lfr by block m b.r) SEE ATTACHED SHEET ,‘.~~~~ 1Q3 EMPTIOSI OV ~ ~~ s ~ OS~~ _f’T~E . - S...1 vi I I ~‘~A (•’,, I~~I A~; o p :~~Tfl~w FOR : Td , MA1~~:;I~RI ii. od uct ior : In l~ 38 . A. N . Go~.ds m i t h c . n c l od~ d t~~at te le i... TD ~ The ident ical costs l imits shown occur because the ’ I same eam ipm en t may be built to operate at several fk’- r en t speeds simply by se t

CoMD Implementation Suite in Emerging Programming Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haque, Riyaz; Reeve, Sam; Juallmes, Luc

CoMD-Em is a software implementation suite of the CoMD [4] proxy app using different emerging programming models. It is intended to analyze the features and capabilities of novel programming models that could help ensure code and performance portability and scalability across heterogeneous platforms while improving programmer productivity. Another goal is to provide the authors and venders with some meaningful feedback regarding the capabilities and limitations of their models. The actual application is a classical molecular dynamics (MD) simulation using either the Lennard-Jones method (LJ) or the embedded atom method (EAM) for primary particle interaction. The code can be extended tomore » support alternate interaction models. The code is expected ro run on a wide class of heterogeneous hardware configurations like shard/distributed/hybrid memory, GPU's and any other platform supported by the underlying programming model.« less

The application of an atomistic J-integral to a ductile crack.

PubMed

Zimmerman, Jonathan A; Jones, Reese E

2013-04-17

In this work we apply a Lagrangian kernel-based estimator of continuum fields to atomic data to estimate the J-integral for the emission dislocations from a crack tip. Face-centered cubic (fcc) gold and body-centered cubic (bcc) iron modeled with embedded atom method (EAM) potentials are used as example systems. The results of a single crack with a K-loading compare well to an analytical solution from anisotropic linear elastic fracture mechanics. We also discovered that in the post-emission of dislocations from the crack tip there is a loop size-dependent contribution to the J-integral. For a system with a finite width crack loaded in simple tension, the finite size effects for the systems that were feasible to compute prevented precise agreement with theory. However, our results indicate that there is a trend towards convergence.

Genome analysis of urease positive Serratia marcescens, co-producing SRT-2 and AAC(6')-Ic with multidrug efflux pumps for antimicrobial resistance.

PubMed

Srinivasan, Vijaya Bharathi; Rajamohan, Govindan

2018-04-05

In this study, we present the genome sequence of Serratia marcescens SM03, recovered from a human gut in India. The final assembly consists of 26 scaffolds (4620 coding DNA sequences, 5.08 Mb, 59.6% G + C ratio) and 79 tRNA genes. Analysis identified novel genes associated with lactose utilization, virulence, P-loop GTPases involved in urease production, CFA/I fimbriae apparatus and Yersinia - type CRISPR proteins. Antibiotic susceptibility testing indicated drug tolerant phenotype and inhibition assays demonstrated involvement of extrusion in resistance. Presence of enzymes SRT-2, AAC(6')-Ic, with additional Ybh transporter and EamA-like efflux pumps signifies the genetic plasticity observed in S. marcescens SM03. Copyright © 2018 Elsevier Inc. All rights reserved.

Atomistic simulation of shocks in single crystal and polycrystalline Ta

NASA Astrophysics Data System (ADS)

Bringa, E. M.; Higginbotham, A.; Park, N.; Tang, Y.; Suggit, M.; Mogni, G.; Ruestes, C. J.; Hawreliak, J.; Erhart, P.; Meyers, M. A.; Wark, J. S.

2011-06-01

Non-equilibrium molecular dynamics (MD) simulations of shocks in Ta single crystals and polycrystals were carried out using up to 360 million atoms. Several EAM and FS type potentials were tested up to 150 GPa, with varying success reproducing the Hugoniot and the behavior of elastic constants under pressure. Phonon modes were studied to exclude possible plasticity nucleation by soft-phonon modes, as observed in MD simulations of Cu crystals. The effect of loading rise time in the resulting microstructure was studied for ramps up to 0.2 ns long. Dislocation activity was not observed in single crystals, unless there were defects acting as dislocation sources above a certain pressure. E.M.B. was funded by CONICET, Agencia Nacional de Ciencia y Tecnología (PICT2008-1325), and a Royal Society International Joint Project award.

Molecular-dynamic study of the influence of temperature on the process of metallic nanocrystals fracture

NASA Astrophysics Data System (ADS)

Demianenko, A. M.; Golovnev, I. F.; Golovneva, E. I.

2017-10-01

The behavior of the fracture processes of a metal nanostructure under deformation in the temperature range 0-550 K was investigated by the molecular dynamics method. An ideal copper crystal was used as a sample in the form of a rectangular parallelepiped with the number of crystalline cells nx = 50, ny = nz = 5 along the corresponding axes. The deformation was carried out by uniaxial stretching of the sample between two clamps (movable and fixed) with a constant speed. The stretching rate varied from 50 to 500 m/s. To describe the interatomic interaction, the Voter many-body EAM potential was used. The effect of temperature on macro characteristics of fracture (the fracture place, the number of fragments formed, the stress on the clamps), and also on the kinetic characteristics (fracture rate, time of formation of maximum stress values on the clamps, mass transfer phenomena and formation of the fracture neck) were revealed.

New Concepts in Indexing *

PubMed Central

Shank, Russell

1965-01-01

Recent trends in indexing emphasize mechanical, not intellectual, developments. Mechanized operations have produced indexes in depth (1) of information on limited areas of science or (2) utilizing limited parameters for analysis. These indexes may include only citations or both useful data and citations of source literature. Both keyword-in-context and citation indexing seem to be passing the test of the marketplace. Mechanical equipment has also been successfully used to manipulate EAM cards for production of index copy. Information centers are increasingly being used as control devices in narrowly defined subject areas. Authors meet growing pressures to participate in information control work by preparing abstracts of their own articles. Mechanized image systems persist, although large systems are scarce and the many small systems may bring only limited relief for information control and retrieval problems. Experimentation and limited development continue on theory and technique of automatic indexing and abstracting. PMID:14306025

What is the copper thin film thickness effect on thermal properties of NiTi/Cu bi-layer?

NASA Astrophysics Data System (ADS)

Fazeli, Sara; Vahedpour, Morteza; Khatiboleslam Sadrnezhaad, Sayed

2017-02-01

Molecular dynamics (MD) simulation was used to study of thermal properties of NiTi/Cu. Embedded atom method (EAM) potentials for describing of inter-atomic interaction and Nose-Hoover thermostat and barostat are employed. The melting of the bi-layers was considered by studying the temperature dependence of the cohesive energy and mean square displacement. To highlight the differences between bi-layers with various copper layer thickness, the effect of copper film thickness on thermal properties containing the cohesive energy, melting point, isobaric heat capacity and latent heat of fusion was estimated. The results show that thermal properties of bi-layer systems are higher than that of their corresponding of pure NiTi. But, these properties of bi-layer systems approximately are independent of copper film thicknesses. The mean square displacement (MSD) results show that, the diffusion coefficients enhance upon increasing of copper film thickness in a linear performance.

Shearing single crystal magnesium in the close-packed basal plane at different temperatures

NASA Astrophysics Data System (ADS)

Han, Ming; Li, Lili; Zhao, Guangming

2018-05-01

Shear behaviors of single crystal magnesium (Mg) in close-packed (0001) basal plane along the [ 1 bar 2 1 bar 0 ], [ 1 2 bar 10 ], [ 10 1 bar 0 ] and [ 1 bar 010 ] directions were studied using molecular dynamics simulations via EAM potential. The results show that both shear stress-strain curves along the four directions and the motion path of free atoms during shearing behave periodic characteristics. It reveals that the periodic shear displacement is inherently related to the crystallographic orientation in single crystal Mg. Moreover, different temperatures in a range from 10 to 750 K were considered, demonstrating that shear modulus decreases with increasing temperatures. The results agree well with the MTS model. It is manifested that the modulus is independent with the shear direction and the size of the atomic model. This work also demonstrates that the classical description of shear modulus is still effective at the nanoscale.

Probing dynamic behavior of electric fields and band diagrams in complex semiconductor heterostructures

NASA Astrophysics Data System (ADS)

Turkulets, Yury; Shalish, Ilan

2018-01-01

Modern bandgap engineered electronic devices are typically made of multi-semiconductor multi-layer heterostructures that pose a major challenge to silicon-era characterization methods. As a result, contemporary bandgap engineering relies mostly on simulated band structures that are hardly ever verified experimentally. Here, we present a method that experimentally evaluates bandgap, band offsets, and electric fields, in complex multi-semiconductor layered structures, and it does so simultaneously in all the layers. The method uses a modest optical photocurrent spectroscopy setup at ambient conditions. The results are analyzed using a simple model for electro-absorption. As an example, we apply the method to a typical GaN high electron mobility transistor structure. Measurements under various external electric fields allow us to experimentally construct band diagrams, not only at equilibrium but also under any other working conditions of the device. The electric fields are then used to obtain the charge carrier density and mobility in the quantum well as a function of the gate voltage over the entire range of operating conditions of the device. The principles exemplified here may serve as guidelines for the development of methods for simultaneous characterization of all the layers in complex, multi-semiconductor structures.

Giant Rashba splitting in 2D organic-inorganic halide perovskites measured by transient spectroscopies

DOE PAGES

Zhai, Yaxin; Baniya, Sangita; Zhang, Chuang; ...

2017-07-28

Two-dimensional (2D) layered hybrid organic-inorganic halide perovskite semiconductors form natural “multiple quantum wells” that have strong spin-orbit coupling due to the heavy elements in their building blocks. This may lead to “Rashba splitting” close to the extrema in the electron bands. We have used a plethora of ultrafast transient, nonlinear optical spectroscopies and theoretical calculations to study the primary (excitons) and long-lived (free carriers) photoexcitations in thin films of 2D perovskite, namely, (C 6H 5C 2H 4NH 3) 2PbI 4. The density functional theory calculation shows the occurrence of Rashba splitting in the plane perpendicular to the 2D barrier. Frommore » the electroabsorption spectrum and photoinduced absorption spectra from excitons and free carriers, we obtain a giant Rashba splitting in this compound, with energy splitting of (40 ± 5) meV and Rashba parameter of (1.6 ± 0.1) eV·Å, which are among the highest Rashba splitting size parameters reported so far. In conclusion, this finding shows that 2D hybrid perovskites have great promise for potential applications in spintronics.« less

Rapid insights from remote sensing in the geosciences

NASA Astrophysics Data System (ADS)

Plaza, Antonio

2015-03-01

The growing availability of capacity computing for atomistic materials modeling has encouraged the use of high-accuracy computationally intensive interatomic potentials, such as SNAP. These potentials also happen to scale well on petascale computing platforms. SNAP has a very general form and uses machine-learning techniques to reproduce the energies, forces, and stress tensors of a large set of small configurations of atoms, which are obtained using high-accuracy quantum electronic structure (QM) calculations. The local environment of each atom is characterized by a set of bispectrum components of the local neighbor density projected on to a basis of hyperspherical harmonics in four dimensions. The computational cost per atom is much greater than that of simpler potentials such as Lennard-Jones or EAM, while the communication cost remains modest. We discuss a variety of strategies for implementing SNAP in the LAMMPS molecular dynamics package. We present scaling results obtained running SNAP on three different classes of machine: a conventional Intel Xeon CPU cluster; the Titan GPU-based system; and the combined Sequoia and Vulcan BlueGene/Q. The growing availability of capacity computing for atomistic materials modeling has encouraged the use of high-accuracy computationally intensive interatomic potentials, such as SNAP. These potentials also happen to scale well on petascale computing platforms. SNAP has a very general form and uses machine-learning techniques to reproduce the energies, forces, and stress tensors of a large set of small configurations of atoms, which are obtained using high-accuracy quantum electronic structure (QM) calculations. The local environment of each atom is characterized by a set of bispectrum components of the local neighbor density projected on to a basis of hyperspherical harmonics in four dimensions. The computational cost per atom is much greater than that of simpler potentials such as Lennard-Jones or EAM, while the communication cost remains modest. We discuss a variety of strategies for implementing SNAP in the LAMMPS molecular dynamics package. We present scaling results obtained running SNAP on three different classes of machine: a conventional Intel Xeon CPU cluster; the Titan GPU-based system; and the combined Sequoia and Vulcan BlueGene/Q. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Dept. of Energy's National Nuclear Security Admin. under Contract DE-AC04-94AL85000.

TU-A-210-00: HIFU Therapies - A Primer

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

High-intensity focused ultrasound (HIFU) has developed rapidly in recent years and is used frequently for clinical treatments in Asia and Europe with increasing clinical use and clinical trial activity in the US, making it an important medical technology with which the medical physics community must become familiar. Akin to medical devices that deliver treatments using ionizing radiation, HIFU relies on emitter geometry to non-invasively form a tight focus that can be used to affect diseased tissue while leaving healthy tissue intact. HIFU is unique in that it does not involve the use of ionizing radiation, it causes thermal necrosis inmore » 100% of the treated tissue volume, and it has an immediate treatment effect. However, because it is an application of ultrasound energy, HIFU interacts strongly with tissue interfaces, which makes treatment planning challenging. In order to appreciate the advantages and disadvantages of HIFU as a thermal therapy, it is important to understand the underlying physics of ultrasound tissue interactions. The first lecture in the session will provide an overview of the physics of ultrasound wave propagation; the mechanism for the accumulation of heat in soft-tissue; image-guidance modalities including temperature monitoring; current clinical applications and commercial devices; active clinical trials; alternate mechanisms of action (future of FUS). The second part of the session will compare HIFU to existing ionization radiation techniques. The difficulties in defining a clear concept of absorbed dose for HIFU will be discussed. Some of the technical challenges that HIFU faces will be described, with an emphasis on how the experience of radiation oncology physicists could benefit the field. Learning Objectives: Describe the basic physics and biology of HIFU, including treatment delivery and image guidance techniques. Summarize existing and emerging clinical applications and manufacturers for HIFU. Understand that thermal ablation with HIFU is likely the first of several applications of the technology Learn about some similarities and differences between HIFU and ionizing radiation in terms of physics and biological effects. Learn about some of the technical challenges HIFU faces that might benefit from the experience of radiation oncology physicists including treatment planning improvements, quality assurance procedures, and treatment risk analysis. David Schlesinger receives research support from Elekta Instruments, AB. Matt Eames is an employee of the Focused Ultrasound Foundation which supports research and clinical trials. Dr. Eames conducts research which is supported by the Focused Ultrasound Foundation.« less

TU-A-210-01: HIFU Physics and Delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eames, M.

2015-06-15

High-intensity focused ultrasound (HIFU) has developed rapidly in recent years and is used frequently for clinical treatments in Asia and Europe with increasing clinical use and clinical trial activity in the US, making it an important medical technology with which the medical physics community must become familiar. Akin to medical devices that deliver treatments using ionizing radiation, HIFU relies on emitter geometry to non-invasively form a tight focus that can be used to affect diseased tissue while leaving healthy tissue intact. HIFU is unique in that it does not involve the use of ionizing radiation, it causes thermal necrosis inmore » 100% of the treated tissue volume, and it has an immediate treatment effect. However, because it is an application of ultrasound energy, HIFU interacts strongly with tissue interfaces, which makes treatment planning challenging. In order to appreciate the advantages and disadvantages of HIFU as a thermal therapy, it is important to understand the underlying physics of ultrasound tissue interactions. The first lecture in the session will provide an overview of the physics of ultrasound wave propagation; the mechanism for the accumulation of heat in soft-tissue; image-guidance modalities including temperature monitoring; current clinical applications and commercial devices; active clinical trials; alternate mechanisms of action (future of FUS). The second part of the session will compare HIFU to existing ionization radiation techniques. The difficulties in defining a clear concept of absorbed dose for HIFU will be discussed. Some of the technical challenges that HIFU faces will be described, with an emphasis on how the experience of radiation oncology physicists could benefit the field. Learning Objectives: Describe the basic physics and biology of HIFU, including treatment delivery and image guidance techniques. Summarize existing and emerging clinical applications and manufacturers for HIFU. Understand that thermal ablation with HIFU is likely the first of several applications of the technology Learn about some similarities and differences between HIFU and ionizing radiation in terms of physics and biological effects. Learn about some of the technical challenges HIFU faces that might benefit from the experience of radiation oncology physicists including treatment planning improvements, quality assurance procedures, and treatment risk analysis. David Schlesinger receives research support from Elekta Instruments, AB. Matt Eames is an employee of the Focused Ultrasound Foundation which supports research and clinical trials. Dr. Eames conducts research which is supported by the Focused Ultrasound Foundation.« less

STENCIL - Strategies and Tools for Environment-friendly Shore Nourishments as Climate Change Impact Low-Regret Measures

NASA Astrophysics Data System (ADS)

Schimmels, Stefan; Cofalla, Catrina; Deutschmann, Björn; Ganal, Caroline; Gijsman, Rik; Hass, H. Christian; Hollert, Henner; Mielck, Finn; Schlurmann, Thorsten; Schüttrumpf, Holger; Shiravani, Gholamreza; Staudt, Franziska; Strusinska, Agnieszka; Visscher, Jan; Wiltshire, Karen; Wolbring, Johanna

2017-04-01

Shore nourishments are regarded as an almost routine coastal protection measure and have been carried out worldwide for several decades. Recent studies generally conclude that "soft" coastal protection measures are an effective option for a sustainable coastal management. However, more research on economic sustainability, species-specific habitat demands and availability of sand deposits is required. Nowadays, the recent paradigm shifts to concepts like the Integrated Coastal Zone Management (ICZM) and the Ecosystem Approach to Management (EAM). For the German Wadden Sea these management objectives are an important issue of the "Wattenmeerstrategie 2100" (MELLUR-SH, 2015), a political strategy report that demands an adaption against the global change and the expected sea-level rise up to the year 2100. Hence, also new concepts and tools for the implementation of more sustainable, effective and environment-friendly shore nourishments are needed. The research project STENCIL joins the expertise of coastal engineers, geologists, biologists and toxicologists in order to make a first step towards the long-term goal of establishing an ICZM and EAM for shore nourishments in the German Wadden Sea. The project focuses on providing improved tools, models and methods for the prediction of coastal hydro- and morphodynamics. Furthermore, the impact of dredging and dumping activities on benthic habitats and their natural regeneration potentials will be evaluated. Since these impacts are still widely uninvestigated, monitoring of dredging areas and the surrounding sites using hydroacoustic devices, aerial photos and sediment samples for grain-size and benthos analysis remains of high importance. In order to develop standardized operative observation methods, analysis and decision-supporting tools, an implementation of field measurements, laboratory experiments as well as conceptual and numerical models is planned. These combined approaches will result in valuable data sets for habitat evaluation, improved prediction methods as well as process and work-flow studies. Finally, a strategy for future planning and monitoring of shore nourishment projects will be established in close cooperation with the coastal authorities. STENCIL has recently started in October 2016 within the research program "Research for sustainable development" (FONA) of the German Federal Ministry of Education and Research (BMBF). The poster will give an overview of the project structure and present the research objectives and methods in more detail.

Sensitivity studies on the impacts of Tibetan Plateau snowpack pollution on the Asian hydrological cycle and monsoon climate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qian, Yun; Flanner, M G; Leung, Lai-Yung R

2011-03-02

The Tibetan Plateau (TP), the highest and largest plateau in the world, has long been identified to be critical in regulating the Asian monsoon climate and hydrological cycle. The snowpack and glaciers over the TP provide fresh water to billions of people in Asian countries, but the TP glaciers have been retreating extensively at a speed faster than any other part of the world. In this study a series of experiments with a global climate model are designed to simulate black carbon (BC) and dust in snow and their radiative forcing and to assess the relative impacts of anthropogenic COmore » 2 and carbonaceous particles in the atmosphere and snow, respectively, on the snowpack over the TP, as well as their subsequent impacts on the Asian monsoon climate and hydrological cycle. Results show a large BC content in snow over the TP, especially the southern slope, with concentration larger than 100 µk/kg. Because of the high aerosol content in snow and large incident solar radiation in the low latitude and high elevation, the TP exhibits the largest surface radiative forcing induced by aerosols (e.g. BC, Dust) in snow compared to other snow-covered regions in the world. The aerosol-induced snow albedo perturbations generate surface radiative forcing of 5-25 W m -2 during spring, with a maximum in April or May. BC-in-snow increases the surface air temperature by around 1.0°C averaged over the TP and reduces snowpack over the TP more than that induced by pre-industrial to present CO 2 increase and carbonaceous particles in the atmosphere during spring. As a result, runoff increases during late winter and early spring but decreases during late spring and early summer (i.e. a trend toward earlier melt dates). The snowmelt efficacy, defined as the snowpack reduction per unit degree of warming induced by the forcing agent, is 1-4 times larger for BC-in-snow than CO 2 increase during April-July, indicating that BC-in-snow more efficiently accelerates snowmelt because the increased net solar radiation induced by reduced albedo melts the snow more efficiently than snow melt due to warming in the air. The TP also influences the South (SAM) and East (EAM) Asian monsoon through its dynamical and thermal forcing. During boreal spring, aerosols are transported by the southwesterly and reach the higher altitude and/or deposited in the snowpack over the TP. While BC and OM in the atmosphere directly absorb sunlight and warm the air, the darkened snow surface polluted by BC absorbs more solar radiation and increases the skin temperature, which warms the air above by the increased sensible heat flux over the TP. Both effects enhance the upward motion of air and spur deep convection along the TP during pre-monsoon season, resulting in earlier onset of the SAM and increase of moisture, cloudiness and convective precipitation over northern India. BC-in-snow has a more significant impact on the EAM in July than CO 2 increase and carbonaceous particles in the atmosphere. Contributed by the significant increase of both sensible heat flux associated with the warm skin temperature and latent heat flux associated with increased soil moisture with long memory, the role of the TP as a heat pump is elevated from spring through summer as the land-sea thermal contrast increases to strengthen the EAM. As a result, both southern China and northern China become wetter, but central China (i.e. Yangtze River Basin) becomes drier - a near zonal anomaly pattern that is consistent with the dominant mode of precipitation variability in East Asia.« less

Development of ingan quantum dots by the Stranski-Krastanov method and droplet heteroepitaxy

NASA Astrophysics Data System (ADS)

Woodward, Jeffrey Michael

The development of InGaN quantum dots (QDs) is both scienti?cally challenging and promising for applications in visible spectrum LEDs, lasers, detectors, electroabsorption modulators and photovoltaics. Such QDs are typically grown using the Stranski-Krastanov (SK) growth mode, in which accumulated in-plane compressive strain induces a transition from 2D to 3D growth. This method has a number of inherent limitations, including the unavoidable formation of a 2D wetting layer and the di?culty of controlling the composition, areal density, and size of the dots. In this research, I have developed InGaN QDs by two methods using a plasma-assisted molecular beam epitaxy reactor. In the ?rst method, InGaN QDs were formed by SK growth mode on (0001) GaN/sapphire. In the second, I have addressed the limitations of the SK growth of InGaN QDs by developing a novel alternative method, which was utilized to grow on both (0001) GaN/sapphire and AlN/sapphire. This method relies upon the ability to form thermodynamically stable In-Ga liquid solutions throughout the entire compositional range at relatively low temperatures. Upon simultaneous or sequential deposition of In and Ga on a substrate, the adatoms form a liquid solution, whose composition is controlled by the ratio of the fluxes of the two constituents FIn/(FIn+FGa ). Depending on the interfacial free energy between the liquid deposit and substrate, the liquid deposit and vapor, and the vapor and substrate, the liquid deposit forms Inx-Ga1- x nano-droplets on the substrate. These nano-droplets convert into InxGa1-xN QDs upon exposure to nitrogen RF plasma. InGaN QDs produced by both methods were investigated in-situ by reflection high-energy electron diffraction and ex-situ by atomic force microscopy, field emission scanning electron microscopy, transmission electron microscopy, high resolution x-ray diffraction, and grazing incidence small angle x-ray scattering. The optical activity and device potential of the QDs were investigated by photoluminescence measurements and the formation and evaluation of PIN devices (in which the intrinsic region contains QDs embedded within a higher bandgap matrix). InGaN QDs with areal densities ranging from 109 to 1011 cm -2 and diameters ranging from 11 to 39 nm were achieved.

Freshwater monsoon related inputs in the Japan Sea: a diatom record from IODP core U1427

NASA Astrophysics Data System (ADS)

Ventura, C. P. L.; Lopes, C.

2016-12-01

Monsoon rainfall is the life-blood of more than half the world's population. Extensive research is being conducted in order to refine projections regarding the impact of anthropogenic climate change on these systems. The East Asian monsoon (EAM) plays a significant role in large-scale climate variability. Due to its importance to global climate and world's population, there is an urgent need for greater understanding of this system, especially during past climate changes. The input of freshwater from the monsoon precipitation brings specific markers, such as freshwater diatoms and specific diatom ecological assemblages that are preserved in marine sediments. Freshwater diatoms are easily identifiable and have been used in the North Pacific to reconstruct environmental conditions (Lopes et al 2006) and flooding episodes (Lopes and Mix, 2009). Here we show preliminary results of freshwater diatoms records that are linked with river discharge due to increase land rainfall that can be derived from Monsoon rainfall. We extend our preliminary study to the past 400ky.

Nano-Indentation of Aluminium Reinforced Metallic Glass Composites: A Molecular Dynamics Study

NASA Astrophysics Data System (ADS)

Yadav, D.; Gupta, P.; Yedla, N.

2018-03-01

Molecular dynamics (MD) simulations are performed for nanoindentation on metal (Al)-metallic glass (Cu50Zr50) reinforced composites to investigate the mechanical properties and the effects of volume percentage on behavior of the load-displacement curves. The interaction among Al-Cu-Zr is modelled using a EAM (Embedded Atom Method) potential. Simulation box size of 100 Å (x) × 100 Å (y) × 100 Å (z) is modelled for investigating the properties of the sintered models by altering the volume percentage on the scale of 5%-20%. Nanoindentation is done along y-direction with a spherical diamond indenter at temperature of 300 K with constant indentation speed of 100 m/s. NVT ensemble is used with a timestep of 0.002 ps. Investigations on the effect of volume percentage show that as volume percentage of Metallic Glass (MG) increases, the corresponding Load required to penetrate inside the sample also increases. As a result of this Hardness also increase as volume percentage varies from 5% to 20%.

Interface structure and contact melting in AgCu eutectic. A molecular dynamics study

NASA Astrophysics Data System (ADS)

Bystrenko, O.; Kartuzov, V.

2017-12-01

Molecular dynamics simulations of the interface structure in binary AgCu eutectic were performed by using the realistic EAM potential. In simulations, we examined the time dependence of the total energy in the process of equilibration, the probability distributions, the composition profiles for the components, and the component diffusivities within the interface zone. It is shown that the relaxation to the equilibrium in the solid state is accompanied by the formation of the steady disordered diffusion zone at the boundary between the crystalline components. At higher temperatures, closer to the eutectic point, the increase in the width of the steady diffusion zone is observed. The particle diffusivities grow therewith to the numbers typical for the liquid metals. Above the eutectic point, the steady zone does not form, instead, the complete contact melting in the system occurs. The results of simulations indicate that during the temperature increase the phenomenon of contact melting is preceded by the similar process spatially localized in the vicinity of the interface.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, Ashish Kumar, E-mail: ashish.memech@gmail.com; Singh, Akhileshwar; Mokhalingam, A.

Atomistic simulations were conducted to estimate the effect of the carbon nanotube (CNT) reinforcement on the mechanical behavior of CNT-reinforced aluminum (Al) nanocomposite. The periodic system of CNT-Al nanocomposite was built and simulated using molecular dynamics (MD) software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). The mechanical properties of the nanocomposite were investigated by the application of uniaxial load on one end of the representative volume element (RVE) and fixing the other end. The interactions between the atoms of Al were modeled using embedded atom method (EAM) potentials, whereas Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential was used for themore » interactions among carbon atoms and these pair potentials are coupled with the Lennard-Jones (LJ) potential. The results show that the incorporation of CNT into the Al matrix can increase the Young’s modulus of the nanocomposite substantially. In the present case, i.e. for approximately 9 with % reinforcement of CNT can increase the axial Young’s modulus of the Al matrix up to 77 % as compared to pure Al.« less

Atomistic modeling of carbon Cottrell atmospheres in bcc iron

NASA Astrophysics Data System (ADS)

Veiga, R. G. A.; Perez, M.; Becquart, C. S.; Domain, C.

2013-01-01

Atomistic simulations with an EAM interatomic potential were used to evaluate carbon-dislocation binding energies in bcc iron. These binding energies were then used to calculate the occupation probability of interstitial sites in the vicinity of an edge and a screw dislocation. The saturation concentration due to carbon-carbon interactions was also estimated by atomistic simulations in the dislocation core and taken as an upper limit for carbon concentration in a Cottrell atmosphere. We obtained a maximum concentration of 10 ± 1 at.% C at T = 0 K within a radius of 1 nm from the dislocation lines. The spatial carbon distributions around the line defects revealed that the Cottrell atmosphere associated with an edge dislocation is denser than that around a screw dislocation, in contrast with the predictions of the classical model of Cochardt and colleagues. Moreover, the present Cottrell atmosphere model is in reasonable quantitative accord with the three-dimensional atom probe data available in the literature.

Particle injector for fluid systems

DOEpatents

Ruch, Jeffrey F.

1997-01-01

A particle injector device provides injection of particles into a liquid eam. The device includes a funnel portion comprising a conical member having side walls tapering from a top opening (which receives the particles) down to a relatively smaller exit opening. A funnel inlet receives a portion of the liquid stream and the latter is directed onto the side walls of the conical member so as to create a cushion of liquid against which the particles impact. A main section of the device includes an inlet port in communication with the exit opening of the funnel portion. A main liquid inlet receives the main portion of the liquid stream at high pressure and low velocity and a throat region located downstream of the main liquid inlet accelerates liquid received by this inlet from the low velocity to a higher velocity so as to create a low pressure area at the exit opening of the funnel portion. An outlet opening of the main section enables the particles and liquid stream to exit from the injector device.

Size-Dependent Surface Energy Density of Spherical Face-Centered-Cubic Metallic Nanoparticles.

PubMed

Wei, Yaochi; Chen, Shaohua

2015-12-01

The surface energy density of nano-sized elements exhibits a significantly size-dependent behavior. Spherical nanoparticle, as an important element in nano-devices and nano-composites, has attracted many interesting studies on size effect, most of which are molecular dynamics (MD) simulations. However, the existing MD calculations yield two opposite size-dependent trends of surface energy density of nanoparticles. In order to clarify such a real underlying problem, atomistic calculations are carried out in the present paper for various spherical face-centered-cubic (fcc) metallic nanoparticles. Both the embedded atom method (EAM) potential and the modified embedded atom method (MEAM) one are adopted. It is found that the size-dependent trend of surface energy density of nanoparticles is not governed by the chosen potential function or variation trend of surface energy, but by the defined radius of spherical nanoparticles in MD models. The finding in the present paper should be helpful for further theoretical studies on surface/interface effect of nanoparticles and nanoparticle-reinforced composites.

Cooling rate dependence and local structure in aluminum monatomic metallic glass

NASA Astrophysics Data System (ADS)

Kbirou, M.; Trady, S.; Hasnaoui, A.; Mazroui, M.

2017-10-01

The local atomic structure in aluminium monatomic metallic glass is studied using molecular dynamics simulations combined with the embedded atom method (EAM). We have used a variety of analytical methods to characterise the atomic configurations of our system: the Pair Distribution Function (PDF), the Common Neighbour Analysis (CNA) and the Voronoi Tessellation Analysis. CNA was used to investigate the order change from liquid to amorphous phases, recognising that the amount of icosahedral clusters increases with the decrease of temperature. The Voronoi analysis revealed that the icosahedral-like polyhedral are the predominant ones. It has been observed that the PDF function shows a splitting in the second peak, which cannot be attributed to the only ideal icosahedral polyhedron 〈0, 0, 12, 0〉, but also to the formation of other Voronoi polyhedra 〈0, 1, 10, 2〉 . Further, the PDFs were then integrated giving the cumulative coordination number in order to compute the fractal dimension (df).

TU-A-210-02: HIFU: Why Should a Radiation Oncology Physicist Pay Attention?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlesinger, D.

High-intensity focused ultrasound (HIFU) has developed rapidly in recent years and is used frequently for clinical treatments in Asia and Europe with increasing clinical use and clinical trial activity in the US, making it an important medical technology with which the medical physics community must become familiar. Akin to medical devices that deliver treatments using ionizing radiation, HIFU relies on emitter geometry to non-invasively form a tight focus that can be used to affect diseased tissue while leaving healthy tissue intact. HIFU is unique in that it does not involve the use of ionizing radiation, it causes thermal necrosis inmore » 100% of the treated tissue volume, and it has an immediate treatment effect. However, because it is an application of ultrasound energy, HIFU interacts strongly with tissue interfaces, which makes treatment planning challenging. In order to appreciate the advantages and disadvantages of HIFU as a thermal therapy, it is important to understand the underlying physics of ultrasound tissue interactions. The first lecture in the session will provide an overview of the physics of ultrasound wave propagation; the mechanism for the accumulation of heat in soft-tissue; image-guidance modalities including temperature monitoring; current clinical applications and commercial devices; active clinical trials; alternate mechanisms of action (future of FUS). The second part of the session will compare HIFU to existing ionization radiation techniques. The difficulties in defining a clear concept of absorbed dose for HIFU will be discussed. Some of the technical challenges that HIFU faces will be described, with an emphasis on how the experience of radiation oncology physicists could benefit the field. Learning Objectives: Describe the basic physics and biology of HIFU, including treatment delivery and image guidance techniques. Summarize existing and emerging clinical applications and manufacturers for HIFU. Understand that thermal ablation with HIFU is likely the first of several applications of the technology Learn about some similarities and differences between HIFU and ionizing radiation in terms of physics and biological effects. Learn about some of the technical challenges HIFU faces that might benefit from the experience of radiation oncology physicists including treatment planning improvements, quality assurance procedures, and treatment risk analysis. David Schlesinger receives research support from Elekta Instruments, AB. Matt Eames is an employee of the Focused Ultrasound Foundation which supports research and clinical trials. Dr. Eames conducts research which is supported by the Focused Ultrasound Foundation.« less

Theoretical Studies of the Structure and the Dynamics on Clean and Chemisorbed Metal Surfaces

NASA Astrophysics Data System (ADS)

Yang, Liqiu

Molecular dynamics (MD) and lattice dynamics (LD) techniques are employed to investigate several phenomena related to the structure and vibrations at metal surfaces. The MD simulations are performed with the many-body interaction potentials obtained using the Embedded-Atom Method (EAM). As specific examples, we present the results for Ag(100) at 300 K and Cu(100) at 150 K, 300 K, and 600 K. The calculated frequencies and polarizations of all surface modes and resonances at the high-symmetry points in the two-dimensional Brillouin zone are in good agreement with available data, as well as, existing lattice dynamics results with force constants obtained from first-principles calculations. Our calculated surface relaxation is also in reasonable agreement with the data. We also test a much simpler lattice dynamics model with nearest neighbor central force interactions, and conclude that it can reproduce the main features of the phonon modes, but only when adjustable surface parameters are used. Additionally, the temperature dependent studies of the phonon line-widths and the mean-square displacement (MSD) of surface atoms are indicative of enhanced surface anharmonicity. On several chemisorbed metal surfaces, for which force constants are not available from first-principles calculations or the EAM, we perform lattice dynamics studies of phonon dispersion curves using simple force-constant models. These studies provide reliable mean-square displacement of surface atoms and can distinguish between possible reconstruction patterns, the results being insensitive to the exact values of the surface parameters. On c(2 times 2)S-Ni(100), it is found that the parallel component of the mean-square displacement for sulfur is around 50% larger than the vertical component, but for the mean-square displacement of oxygen atoms in the system c(2 times 2)O-Ni(100), the opposite is the case. As regards surface reconstruction, for both p(2 times 1)O-Ag(110) and p(2 times 1)O-Ni(110) surfaces, it is concluded that a substrate missing-row type reconstruction is induced by the adsorbates, but the local symmetry is C_{2v} with oxygen atoms at the long-bridge sites for the former and C_{s} with (110) being the only symmetry axis for the latter. In the above theoretical analysis, close contacts are made to many available experimental results such as surface phonon dispersion curves, interlayer relaxations, and Debye -Waller factors and adsorbate-substrate bond lengths.

Far-Field to Near-Field Coupling for Enhancing Light-Matter Interaction

NASA Astrophysics Data System (ADS)

Bonakdar, Alireza

This thesis reports on theoretical, modeling, and experimental research within the framework of a key scientific question, which is enhancing the coupling between diffraction-limited far-field and sub-wavelength quantum emitter/absorber. A typical optoelectronic device delivers an optical process such as light detection (e.g. photodetector) or light intensity modulation (e.g. electro-absorptive modulator). In conventional devices, optical process is in the form of far-field or guided wave modes. The main aim of this thesis is to show that converting these modes into near-field domain can enhance the performance of the optoelectronic device. Light in the form of far-field can be converted into near-field domain by the optical antenna. Among different optoelectronic devices, this thesis focuses mainly on integrating the optical antenna with infrared photodetectors. The available semiconductors have weak infrared absorption that reduces light detection efficiency. Integration of the optical antenna with infrared absorber (such as quantum wells in quantum well infrared photodetector (QWIP)) increases the infrared absorption. Particularly this integration is favorable as the optical antenna has low metallic loss in infrared region. The author of this thesis believes that optical antenna has unique properties in confining light on the scale of deep sub-wavelength, enhancing electric field intensity and delivering optical energy to semiconductor absorbers. These properties are reaching into practical applications only if overall optical performance is low loss, parameter free (independent of optical parameters such a polarization and angle of incident) and broadband. In this thesis, the integration of optical antenna with infrared photodetectors and thermophotovoltaic are researched and developed which satisfy the aforementioned criteria. In addition, several different optical antennas have been designed, fabricated and characterized in order to analyze and demonstrate the improvement of infrared absorption. In terms of design, novel optical antennas were simulated and proposed for a variety of infrared photodetectors such as a quantum well infrared photodetector, metal-insulator-metal detector, Schottky infrared photodetector, and two-photon absorption infrared detector. Antenna analyzes are not limited to light detection as a chapter of this thesis devoted on design and develop of a low power and ultrafast all-optical/optomechanical switchable antenna. The rest of the manuscript contains the novel lithography method in order to fabricate optical antennas with low cost and in cm-scale area. The method is based on the microsphere photolithography that expose photoresist underneath each microsphere with a focused intensive light -so called photonic nanojet. The developed lithography method takes advantage of microscopic range of optical path (micro-optics) in microsphere lenses that allows to push the exposure wavelength beyond deep UV region, where the refractive optics becomes impractical due to severe material absorption. The author believes that micro-optics lithography is an excellent candidate for large area and high throughput fabrication of sub-100-nm feature sizes in periodic array. In particular, this method facilitates the feasibility of metasurfaces and metamaterials, optical coating with efficient photon extraction/trapping, and highly sensitive bio-sensors in near IR and visible ranges of spectrum.

Results of closed cycle MHD power generation tests with a helium-cesium working fluid

NASA Technical Reports Server (NTRS)

Sovie, R. J.

1977-01-01

The cross-sectional dimensions of the MHD channel in the NASA Lewis closed loop facility have been reduced to 3.8 x 11.4 cm. Tests were run in this channel using a helium-cesium working fluid at stagnation pressures of 1.6 x 10 to the 5th N/sq m, stagnation temperatures of 2000-2060 K and an entrance Mach number of 0.36. In these tests Faraday open circuit voltages of 200 V were measured which correspond to a Faraday field of 1750 V/m. Power generation tests were run for different groups of electrode configurations and channel lengths. Hall fields up to 1450 V/m were generated. Power extraction per electrode of 183 W and power densities of 1.7 MW/cu m have been obtained. A total power output of 2 kW was generated for tests with 14 electrodes. The power densities obtained in this channel represent a factor of 3 improvement over those reported for the m = 0.2 channel at the last EAM Symposium.

A Comparison of the Predictive Capabilities of the Embedded-Atom Method and Modified Embedded-Atom Method Potentials for Lithium

DOE PAGES

Vella, Joseph R.; Stillinger, Frank H.; Panagiotopoulos, Athanassios Z.; ...

2015-07-23

Here, we compare six lithium potentials by examining their ability to predict coexistence properties and liquid structure using molecular dynamics. All potentials are of the embedded-atom-method (EAM) type. The coexistence properties we focus on are the melting curve, vapor pressure, saturated liquid density, and vapor-liquid surface tension. For each property studied, the simulation results are compared to available experimental data in order to properly assess the accuracy of each potential. We find that the Cui 2NN MEAM is the most robust potential, giving adequate agreement with most of the properties examined. For example, the zero-pressure melting point of this potentialmore » is shown to be around 443 K, while experimentally is it about 454 K. This potential also gives excellent agreement with saturated liquid densities, even though no liquid properties were used in the fitting procedure. Our study allows us to conclude that the Cui 2NN MEAM should be used for further simulations of lithiums.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Bo; Zhao, Hongwei, E-mail: hwzhao@jlu.edu.cn, E-mail: khl69@163.com; Zhao, Dan

It has always been a critical issue to understand the material removal behavior of Vibration-Assisted Machining (VAM), especially on atomic level. To find out the effects of vibration frequency on material removal response, a three-dimensional molecular dynamics (MD) model has been established in this research to investigate the effects of scratched groove, crystal defects on the surface quality, comparing with the Von Mises shear strain and tangential force in simulations during nano-scratching process. Comparisons are made among the results of simulations from different vibration frequency with the same scratching feed, depth, amplitude and crystal orientation. Copper potential in this simulationmore » is Embedded-Atom Method (EAM) potential. Interaction between copper and carbon atoms is Morse potential. Simulational results show that higher frequency can make groove smoother. Simulation with high frequency creates more dislocations to improve the machinability of copper specimen. The changing frequency does not have evident effects on Von Mises shear strain. Higher frequency can decrease the tangential force to reduce the consumption of cutting energy and tool wear. In conclusion, higher vibration frequency in VAM on mono-crystalline copper has positive effects on surface finish, machinablility and tool wear reduction.« less

A tungsten-rhenium interatomic potential for point defect studies

DOE PAGES

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

2018-05-28

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

Thermodynamic Behavior of Nano-sized Gold Clusters on the (001) Surface

NASA Technical Reports Server (NTRS)

Paik, Sun M.; Yoo, Sung M.; Namkung, Min; Wincheski, Russell A.; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

We have studied thermal expansion of the surface layers of the hexagonally reconstructed Au (001) surface using a classical Molecular Dynamics (MD) simulation technique with an Embedded Atomic Method (EAM) type many-body potential. We find that the top-most hexagonal layer contracts as temperature increases, whereas the second layer expands or contracts depending on the system size. The magnitude of expansion coefficient of the top layer is much larger than that of the other layers. The calculated thermal expansion coefficients of the top-most layer are about -4.93 x 10(exp -5)Angstroms/Kelvin for the (262 x 227)Angstrom cluster and -3.05 x 10(exp -5)Angstroms/Kelvin for (101 x 87)Angstrom cluster. The Fast Fourier Transform (FFT) image of the atomic density shows that there exists a rotated domain of the top-most hexagonal cluster with rotation angle close to 1 degree at temperature T less than 1000Kelvin. As the temperature increases this domain undergoes a surface orientational phase transition. These predictions are in good agreement with previous phenomenological theories and experimental studies.

Defect structures induced by high-energy displacement cascades in γ uranium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Yinbin; Beeler, Benjamin; Deo, Chaitanya

Displacement cascade simulations were conducted for the c uranium system based on molecular dynamics. A recently developed modified embedded atom method (MEAM) potential was employed to replicate the atomic interactions while an embedded atom method (EAM) potential was adopted to help characterize the defect structures induced by the displacement cascades. The atomic displacement process was studied by providing primary knock-on atoms (PKAs) with kinetic energies from 1 keV to 50 keV. The influence of the PKA incident direction was examined. The defect structures were analyzed after the systems were fully relaxed. The states of the self-interstitial atoms (SIAs) were categorizedmore » into various types of dumbbells, the crowdion, and the octahedral interstitial. The voids were determined to have a polyhedral shape with {110} facets. The size distribution of the voids was also obtained. The results of this study not only expand the knowledge of the microstructural evolution in irradiated c uranium, but also provide valuable references for the radiation-induced defects in uranium alloy fuels.« less

Effect of temperature and geometric parameters on elastic properties of tungsten nanowire: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Saha, Sourav; Mojumder, Satyajit; Mahboob, Monon; Islam, M. Zahabul

2016-07-01

Tungsten is a promising material and has potential use as battery anode. Tungsten nanowires are gaining attention from researchers all over the world for this wide field of application. In this paper, we investigated effect of temperature and geometric parameters (diameter and aspect ratio) on elastic properties of Tungsten nanowire. Aspect ratios (length to diameter ratio) considered are 8:1, 10:1, and 12:1 while diameter of the nanowire is varied from 1-4 nm. For 2 nm diameter sample (aspect ratio 10:1), temperature is varied (10K ~ 1500K) to observe elastic behavior of Tungsten nanowire under uniaxial tensile loading. EAM potential is used for molecular dynamic simulation. We applied constant strain rate of 109 s-1 to deform the nanowire. Elastic behavior is expressed through stress vs. strain plot. We also investigated the fracture mechanism of tungsten nanowire and radial distribution function. Investigation suggests peculiar behavior of Tungsten nanowire in nano-scale with double peaks in stress vs. strain diagram. Necking before final fracture suggests that actual elastic behavior of the material is successfully captured through atomistic modeling.

Molecular dynamics study of mechanical properties of carbon nanotube reinforced aluminum composites

NASA Astrophysics Data System (ADS)

Srivastava, Ashish Kumar; Mokhalingam, A.; Singh, Akhileshwar; Kumar, Dinesh

2016-05-01

Atomistic simulations were conducted to estimate the effect of the carbon nanotube (CNT) reinforcement on the mechanical behavior of CNT-reinforced aluminum (Al) nanocomposite. The periodic system of CNT-Al nanocomposite was built and simulated using molecular dynamics (MD) software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). The mechanical properties of the nanocomposite were investigated by the application of uniaxial load on one end of the representative volume element (RVE) and fixing the other end. The interactions between the atoms of Al were modeled using embedded atom method (EAM) potentials, whereas Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential was used for the interactions among carbon atoms and these pair potentials are coupled with the Lennard-Jones (LJ) potential. The results show that the incorporation of CNT into the Al matrix can increase the Young's modulus of the nanocomposite substantially. In the present case, i.e. for approximately 9 with % reinforcement of CNT can increase the axial Young's modulus of the Al matrix up to 77 % as compared to pure Al.

A tungsten-rhenium interatomic potential for point defect studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

Protective Effect of Eburicoic Acid of the Chicken of the Woods Mushroom, Laetiporus sulphureus (Higher Basidiomycetes), Against Gastric Ulcers in Mice.

PubMed

Wang, Junzhi; Sun, Wenjun; Luo, Huajun; He, Haibo; Deng, Weiqiao; Zou, Kun; Liu, Can; Song, Jing; Huang, Wenfeng

2015-01-01

In this study, we investigated the anti-inflammatory and tumor-inhibiting effects of eburicoic acid, the main bioactive component in the Laetiporus sulphureus, on gastric ulcers. A total of 48 Kunming mice were randomly divided into six groups: control, model, OL (omeprazole, 20 mg/kg/day, orally), EA-L (eburicoic acid, 10 mg/kg/day, orally), EA-M (eburicoic acid, 20 mg/kg/day, orally), and EA-H (eburicoic acid, 40 mg/kg/day, orally). Gastric ulcers were induced in mice by administering 80% ethanol containing 15 mg/mL aspirin (10.0 mL/kg, i.g.) 4 hours after drug administration on day 5. The ulcer index and H+/K+-ATPase activity were evaluated in vivo. Computer-aided molecular docking simulated the interaction between eburicoic acid and H+/K+-ATPase. The results showed that the oral administration of eburicoic acid protected the gastric mucosa from gastric lesions morphologically and especially attenuated H+/K+-ATPase activity. The results of this study indicate that the gastric protective effect of eburicoic acid might inhibit gastric acid.

A Fortran 90 Hartree-Fock program for one-dimensional periodic π-conjugated systems using Pariser-Parr-Pople model

NASA Astrophysics Data System (ADS)

Kondayya, Gundra; Shukla, Alok

2012-03-01

Pariser-Parr-Pople (P-P-P) model Hamiltonian is employed frequently to study the electronic structure and optical properties of π-conjugated systems. In this paper we describe a Fortran 90 computer program which uses the P-P-P model Hamiltonian to solve the Hartree-Fock (HF) equation for infinitely long, one-dimensional, periodic, π-electron systems. The code is capable of computing the band structure, as also the linear optical absorption spectrum, by using the tight-binding and the HF methods. Furthermore, using our program the user can solve the HF equation in the presence of a finite external electric field, thereby, allowing the simulation of gated systems. We apply our code to compute various properties of polymers such as trans-polyacetylene, poly- para-phenylene, and armchair and zigzag graphene nanoribbons, in the infinite length limit. Program summaryProgram title: ppp_bulk.x Catalogue identifier: AEKW_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEKW_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 87 464 No. of bytes in distributed program, including test data, etc.: 2 046 933 Distribution format: tar.gz Programming language: Fortran 90 Computer: PCs and workstations Operating system: Linux, Code was developed and tested on various recent versions of 64-bit Fedora including Fedora 14 (kernel version 2.6.35.12-90). Classification: 7.3 External routines: This program needs to link with LAPACK/BLAS libraries compiled with the same compiler as the program. For the Intel Fortran Compiler we used the ACML library version 4.4.0, while for the gfortran compiler we used the libraries supplied with the Fedora distribution. Nature of problem: The electronic structure of one-dimensional periodic π-conjugated systems is an intense area of research at present because of the tremendous interest in the physics of conjugated polymers and graphene nanoribbons. The computer program described in this paper provides an efficient way of solving the Hartree-Fock equations for such systems within the P-P-P model. In addition to the Bloch orbitals, band structure, and the density of states, the program can also compute quantities such as the linear absorption spectrum, and the electro-absorption spectrum of these systems. Solution method: For a one-dimensional periodic π-conjugated system lying in the xy-plane, the single-particle Bloch orbitals are expressed as linear combinations of p-orbitals of individual atoms. Then using various parameters defining the P-P-P Hamiltonian, the Hartree-Fock equations are set up as a matrix eigenvalue problem in the k-space. Thereby, its solutions are obtained in a self-consistent manner, using the iterative diagonalizing technique at several k points. The band structure and the corresponding Bloch orbitals thus obtained are used to perform a variety of calculations such as the density of states, linear optical absorption spectrum, electro-absorption spectrum, etc. Running time: Most of the examples provided take only a few seconds to run. For a large system, however, depending on the system size, the run time may be a few minutes to a few hours.

Pentacyanoiron(II) as an electron donor group for nonlinear optics: medium-responsive properties and comparisons with related pentaammineruthenium(II) complexes.

PubMed

Coe, Benjamin J; Harries, Josephine L; Helliwell, Madeleine; Jones, Lathe A; Asselberghs, Inge; Clays, Koen; Brunschwig, Bruce S; Harris, James A; Garín, Javier; Orduna, Jesús

2006-09-20

In this article, we describe a series of complex salts in which electron-rich {Fe(II)(CN)(5)}(3)(-) centers are coordinated to pyridyl ligands with electron-accepting N-methyl/aryl-pyridinium substituents. These compounds have been characterized by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering (HRS) at 1064 nm, and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d --> pi* metal-to-ligand charge-transfer (MLCT) bands. The relatively large static first hyperpolarizabilities, beta(0), increase markedly on moving from aqueous to methanol solutions, accompanied by large red-shifts in the MLCT transitions. Acidification of aqueous solutions allows reversible switching of the linear and NLO properties, as shown via both HRS and Stark experiments. Time-dependent density functional theory and finite field calculations using a polarizable continuum model yield relatively good agreement with the experimental results and confirm the large decrease in beta(0) on protonation. The Stark-derived beta(0) values are generally larger for related {Ru(II)(NH(3))(5)}(2+) complexes than for their {Fe(II)(CN)(5)}(3)(-) analogues, consistent with the HRS data in water. However, the HRS data in methanol show that the stronger solvatochromism of the Fe(II) complexes causes their NLO responses to surpass those of their Ru(II) counterparts upon changing the solvent medium.

Theoretical analyses of the effects on the linear and quadratic nonlinear optical properties of N-arylation of pyridinium groups in stilbazolium dyes.

PubMed

Coe, Benjamin J; Beljonne, David; Vogel, Henryk; Garín, Javier; Orduna, Jesús

2005-11-10

N-Arylation of the pyridinium electron acceptor unit in stilbazolium chromophores has been found by previous experimental hyper-Rayleigh scattering and electronic Stark effect (electroabsorption) spectroscopic studies to lead to substantial increases in the static first hyperpolarizability beta(0). We show here that INDO/SCI calculations on the isolated cations trans-4'-(dimethylamino)-N-R-4-stilbazolium (R = methyl 1, phenyl 2, 2,4-dinitrophenyl 3, or 2-pyrimidyl 4) predict only slight red-shifts in the energy of the intramolecular charge-transfer (ICT) transition and accompanying relatively small changes in beta(0) on moving along the series. The inclusion of acetonitrile solvent using a polarizable continuum model affords a somewhat better agreement with the experimental data, especially the red-shifting of the ICT transition and the increase in beta(0) on going from 1 to 4. Time-dependent density functional theory (TD-DFT), finite field, and coupled perturbed Hartree-Fock calculations reproduce even more closely the empirical data and trends; the latter two approaches lead to the highest quadratic nonlinear optical (NLO) response of the studied chromophores for 3, for which the predicted beta(0) is ca. 50-100% larger than that of the analogous N-methylated cation 1. Although the TD-DFT and INDO/SCI approaches give quite different results for ground- and excited-state dipole moments, the overall conclusions of these two methods regarding the ICT absorption and NLO responses are similar.

Heterogeneous wireless/wireline optical access networks with the R-EAT as backend component

NASA Astrophysics Data System (ADS)

Hagedorn, Klaus; Gindera, Ralf; Stohr, Andreas; Jager, Dieter

2004-09-01

A heterogeneous wireless/wireline optical transmission link using a reflection type electroabsorption transceiver (R-EAT) is presented. Simultaneous transmission of full-duplex broadband wireless LAN (WLAN) channels and 1Gb/s base band data is experimentally demonstrated. The system link employs sub-carrier multiplexing (SCM) and two optical channels for full duplex transmission of various analog WLAN channels and downlink digital base band data. The developed link architecture is suitable for simultaneous transmission of broadband wireline and wireless signals, it enables the coexistence and interoperability between wireline and wireless access technologies. The developed R-EAT component employed in this wireline/wireless access system, features "single-chip-component" base stations in access networks with star type topology where only a single optical fiber is used for bidirectional optical transmission. The R-EAT can be used within the optical C-band (1530- 1560nm) and is suitable for (D)WDM networks. Bit error rate measurements demonstrate the capabilities of the R-EAT for 1Gb/s base band transmission. The analog performance for WLAN transmission is characterised by a spurious free dynamic range (SFDR) of more than 75dB and 90dB for uplink and downlink transmission, respectively. The link gain for uplink and downlink transmission is -42dB and -37dB, respectively. The demonstrates the analog performances of the R-EAT for being used in wireless access networks such as W-LAN.

First evidence of denitrification vis-à-vis monsoon in the Arabian Sea since Late Miocene.

PubMed

Tripathi, Shubham; Tiwari, Manish; Lee, Jongmin; Khim, Boo-Keun

2017-02-21

In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2 Ma) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. We find that (i) the SAM was persistently weaker from ~10.2 to 3.1 Ma; it did not intensify at ~8 Ma in contrast to a few previous studies, (ii) on tectonic timescale, both the SAM and the East Asian Monsoon (EAM) varied synchronously, (iii) the first evidence of denitrification and productivity/SAM intensification was at ~3.2-2.8 Ma that coincided with Mid-Pliocene Warm Period (MPWP), and (iv) the modern strength of the OMZ where denitrification is a permanent feature was attained at ~1.0 Ma.

First evidence of denitrification vis-à-vis monsoon in the Arabian Sea since Late Miocene

NASA Astrophysics Data System (ADS)

Tripathi, Shubham; Tiwari, Manish; Lee, Jongmin; Khim, Boo-Keun; Pandey, Dhananjai K.; Clift, Peter D.; Kulhanek, Denise K.; Andò, Sergio; Bendle, James A. P.; Aharonovich, Sophia; Griffith, Elizabeth M.; Gurumurthy, Gundiga P.; Hahn, Annette; Iwai, Masao; Kumar, Anil; Kumar, A. Ganesh; Liddy, Hannah M.; Lu, Huayu; Lyle, Mitchell W.; Mishra, Ravi; Radhakrishna, Tallavajhala; Routledge, Claire M.; Saraswat, Rajeev; Saxena, Rakesh; Scardia, Giancarlo; Sharma, Girish K.; Singh, Arun D.; Steinke, Stephan; Suzuki, Kenta; Tauxe, Lisa; Xu, Zhaokai; Yu, Zhaojie

2017-02-01

In the Arabian Sea, South Asian monsoon (SAM)-induced high surface water productivity coupled with poor ventilation of intermediate water results in strong denitrification within the oxygen minimum zone (OMZ). Despite the significance of denitrification in the Arabian Sea, we have no long-term record of its evolution spanning the past several million years. Here, we present the first record of denitrification evolution since Late Miocene (~10.2 Ma) in the Eastern Arabian Sea, where the SAM generates moderate surface water productivity, based on the samples retrieved during the International Ocean Discovery Program (IODP) Expedition 355. We find that (i) the SAM was persistently weaker from ~10.2 to 3.1 Ma it did not intensify at ~8 Ma in contrast to a few previous studies, (ii) on tectonic timescale, both the SAM and the East Asian Monsoon (EAM) varied synchronously, (iii) the first evidence of denitrification and productivity/SAM intensification was at ~3.2-2.8 Ma that coincided with Mid-Pliocene Warm Period (MPWP), and (iv) the modern strength of the OMZ where denitrification is a permanent feature was attained at ~1.0 Ma.

Strain-Rate Dependence of Deformation-Twinning in Tantalum

NASA Astrophysics Data System (ADS)

Abeywardhana, Jayalath; Germann, Tim; Ravelo, Ramon

2017-06-01

Large-Scale molecular dynamics (MD) simulations are used to model quasi-isentropic compression and expansion (QIC) in tantalum crystals varying the rate of deformation between the range 108 -1012s-1 and compressive pressures up to 100 GPa. The atomic interactions were modeled employing an embedded-atom method (EAM) potential of Ta. Isentropic expansion was done employing samples initially compressed to pressures of 60 and 100 GPa followed by uniaxial and quasi-isentropically expansion to zero pressure. The effect of initial dislocation density on twinning was also examined by varying the initial defect density of the Ta samples (1010 -1012cm-2). At these high-strain rates, a threshold in strain-rate on deformation twining is observed. Under expansion or compression, deformation twinning increases with strain rate for strain-rates >109s-1 . Below this value, small fraction of twins nucleates but anneal out with time. Samples with lower fraction of twins equilibrate to defect states containing higher screw dislocation densities from those with initially higher twinning fractions. This work was supported by the Department of Energy under contract DE-AC52-06NA25396 and by the Air Force Office of Scientific Research under AFOSR Award No. FA9550-12-1-0476.

Endoscopic neurosurgery "around the corner" with a rigid endoscope. Technical note.

PubMed

Hopf, N J

1999-03-01

Endoscopically "working around the corner" is presently restricted to the use of flexible endoscopes or an endoscope-assisted microneurosurgical (EAM) technique. In order to overcome the limitations of these solutions, endoscopic equipment and techniques were developed for "working around the corner" with rigid endoscopes. A steering insert with a 5 French working channel is capable of steering instruments around the corner by actively bending the guiding track and consecutively the instrument. A special fixation device enables strict axial rotation of the endoscope in the operating field. Endoscopic procedures "around the corner", including aqueductal stenting, pellucidotomy, third ventriculostomy and biopsy were performed in human cadavers. Special features of the used pediatric neuroendoscope system, i.e., reliable fixation, axial rotation, and controlled steering of instruments, increase the safety and reduce the surgical traumatization in selected cases, such as obstructive hydrocephalus due to a mass lesion in the posterior third ventricle, since endoscopic third ventriculostomy and biopsy can be performed through the same burr hole trephination. Limitations of this technique are given by the size of the foramen of Monro and the height of the third ventricle as well as by the bending angle of the instruments (40-50 degrees).

Atomic Scale Investigation of Structural Properties and Glass Forming Ability of Ti100-x Al x Metallic Glasses

NASA Astrophysics Data System (ADS)

Tahiri, M.; Hasnaoui, A.; Sbiaai, K.

2018-03-01

In this work, we employed molecular dynamics (MD) simulations to study Ti-Al metallic glasses (MGs) using the embedded atom method (EAM) potential to model the atomic interaction with different compositions. The results showed evidence of the metallic glass formation induced by the split occurring in the second peak of the radial distribution function (RDF) curves implying both Ti and Al atoms. The common neighbor analysis (CNA) method confirmed the presence of the icosahedral clusters with a maximum amount observed for an alloy with 75 pct of Al. Analysis of coordination numbers (CNs) indicated that the total CNs are nearly unchanged in these systems. Finally, Voronoi tessellation analyses (VTA) showed a higher value of the number of icosahedral units at Ti25Al75 composition. This specific composition represents a nearby peritectic point localized at a low melting point in the Ti-Al binary phase diagram. The glass forming ability (GFA) becomes important when the fraction of Al increases by forming and connecting "icosahedral-like" clusters (12-coordinated <0, 0, 12, 0> and 13-coordinated <0, 1, 10, 2>) and by playing a main role in the structure stability of the Ti-Al MGs.

Atomic Scale Investigation of Structural Properties and Glass Forming Ability of Ti100- x Al x Metallic Glasses

NASA Astrophysics Data System (ADS)

Tahiri, M.; Hasnaoui, A.; Sbiaai, K.

2018-06-01

In this work, we employed molecular dynamics (MD) simulations to study Ti-Al metallic glasses (MGs) using the embedded atom method (EAM) potential to model the atomic interaction with different compositions. The results showed evidence of the metallic glass formation induced by the split occurring in the second peak of the radial distribution function (RDF) curves implying both Ti and Al atoms. The common neighbor analysis (CNA) method confirmed the presence of the icosahedral clusters with a maximum amount observed for an alloy with 75 pct of Al. Analysis of coordination numbers (CNs) indicated that the total CNs are nearly unchanged in these systems. Finally, Voronoi tessellation analyses (VTA) showed a higher value of the number of icosahedral units at Ti25Al75 composition. This specific composition represents a nearby peritectic point localized at a low melting point in the Ti-Al binary phase diagram. The glass forming ability (GFA) becomes important when the fraction of Al increases by forming and connecting "icosahedral-like" clusters (12-coordinated <0, 0, 12, 0> and 13-coordinated <0, 1, 10, 2>) and by playing a main role in the structure stability of the Ti-Al MGs.

Modeling of crack growth under mixed-mode loading by a molecular dynamics method and a linear fracture mechanics approach

NASA Astrophysics Data System (ADS)

Stepanova, L. V.

2017-12-01

Atomistic simulations of the central crack growth process in an infinite plane medium under mixed-mode loading using Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), a classical molecular dynamics code, are performed. The inter-atomic potential used in this investigation is the Embedded Atom Method (EAM) potential. Plane specimens with an initial central crack are subjected to mixed-mode loadings. The simulation cell contains 400,000 atoms. The crack propagation direction angles under different values of the mixity parameter in a wide range of values from pure tensile loading to pure shear loading in a wide range of temperatures (from 0.1 K to 800 K) are obtained and analyzed. It is shown that the crack propagation direction angles obtained by molecular dynamics coincide with the crack propagation direction angles given by the multi-parameter fracture criteria based on the strain energy density and the multi-parameter description of the crack-tip fields. The multi-parameter fracture criteria are based on the multi-parameter stress field description taking into account the higher order terms of the Williams series expansion of the crack tip fields.

Alpine glacier change in the Eastern Altun mountains of Northwest China during 1972-2010.

PubMed

Yu, Xinyang; Lu, Changhe

2015-01-01

Accurately mapping and monitoring glacier changes over decades is important for providing information to support sustainable use of water resource in arid regions of northwest China. Since 1970, glaciers in the Eastern Altun Mountains showed remarkable recession. Further study is indispensable to indicate the extent and amplitude of glacial change at basin and individual glacier scale. In this study, spatiotemporal glacier changes referring to the year 1972, 1990, 2000 and 2010 were studied for the Eastern Altun Mountains using Landsat MSS/TM/ETM+ images and glacier volume-area scaling. The results demonstrated that the total area and volume of glaciers in EAMs decreased significantly by 10.70±0.57 km² (19.56±10.41%) and 0.61±0.03 km³ (23.19±11.40%) during 1972-2010, respectively. More than half of the total receding area occurred during 1990-2000, primarily due to higher temperature increasing. However, varied response of individual glaciers indicated that glacier change was also affected by glacier dynamics, which was related to local topography. In addition, five glaciers unrecorded in the glacier inventory of China were reported in this study.

Alpine Glacier Change in the Eastern Altun Mountains of Northwest China during 1972-2010

PubMed Central

Yu, Xinyang; Lu, Changhe

2015-01-01

Accurately mapping and monitoring glacier changes over decades is important for providing information to support sustainable use of water resource in arid regions of northwest China. Since 1970, glaciers in the Eastern Altun Mountains showed remarkable recession. Further study is indispensable to indicate the extent and amplitude of glacial change at basin and individual glacier scale. In this study, spatiotemporal glacier changes referring to the year 1972, 1990, 2000 and 2010 were studied for the Eastern Altun Mountains using Landsat MSS/TM/ETM+ images and glacier volume-area scaling. The results demonstrated that the total area and volume of glaciers in EAMs decreased significantly by 10.70±0.57 km² (19.56±10.41%) and 0.61±0.03 km³ (23.19±11.40%) during 1972–2010, respectively. More than half of the total receding area occurred during 1990–2000, primarily due to higher temperature increasing. However, varied response of individual glaciers indicated that glacier change was also affected by glacier dynamics, which was related to local topography. In addition, five glaciers unrecorded in the glacier inventory of China were reported in this study. PMID:25723669

Local density variation of gold nanoparticles in aquatic environments

NASA Astrophysics Data System (ADS)

Hosseinzadeh, F.; Shirazian, F.; Shahsavari, R.; Khoei, A. R.

2016-10-01

Gold (Au) nanoparticles are widely used in diagnosing cancer, imaging, and identification of therapeutic methods due to their particular quantum characteristics. This research presents different types of aqueous models and potentials used in TIP3P, to study the effect of the particle size and density of Au clusters in aquatic environments; so it can be useful to facilitate future investigation of the interaction of proteins with Au nanoparticles. The EAM potential is used to model the structure of gold clusters. It is observed that in the systems with identical gold/water density and different cluster radii, gold particles are distributed in aqueous environment almost identically. Thus, Au particles have identical local densities, and the root mean square displacement (RMSD) increases with a constant slope. However in systems with constant cluster radii and different gold/water densities, Au particle dispersion increases with density; as a result, the local density decreases and the RMSD increases with a larger slope. In such systems, the larger densities result in more blunted second peaks in gold-gold radial distribution functions, owing to more intermixing of the clusters and less FCC crystalline features at longer range, a mechanism that is mediated by the competing effects of gold-water and gold-gold interactions.

Nanodroplet impact onto solid platinum surface: Spreading and bouncing

NASA Astrophysics Data System (ADS)

Lussier, Daniel; Ventikos, Yiannis

2009-11-01

The impact of droplets onto solid surfaces is found in a huge variety of natural and technological applications, from rain drops splashing on the pavement, to material manufacturing by molten droplet deposition. Taking inspiration from existing microfluidic technologies (i.e. lab-on-chip), there is increasing interest in the use of nanodroplets (D < 100 nm) for a number of applications such as drug delivery and semiconductor device manufacturing. However, as the size of the droplet is reduced into the nanoscale, the direct use of previously obtained macroscopic results is not guaranteed. At the nanoscale, important effects due to the molecular nature of the fluid, thermal fluctuations and reduced dimensionality can play a critical role in determining system dynamics. In this paper we present the results of large-scale, fully atomistic, three-dimensional molecular dynamics (MD) simulation of an argon nanodroplet (D = 18 nm, 54 000 atoms) impact onto a solid platinum surface, using the LAMMPS software package. The fluid argon is modeled using the well-known Lennard-Jones (LJ) potential, while the embedded-atom model (EAM) potential is used for the solid platinum. By varying both the impact velocities (10-1000 m/s) and the wettability of the solid surface a wide range of impact behaviors is observed, from smooth spreading, to bouncing recoil, pointing towards a wide array of potential applications.

Amniotic membrane scaffolds enable the development of tissue-engineered urothelium with molecular and ultrastructural properties comparable to that of native urothelium.

PubMed

Jerman, Urška Dragin; Veranič, Peter; Kreft, Mateja Erdani

2014-04-01

The amniotic membrane (AM) is a naturally derived biomaterial that possesses biological and mechanical properties of great importance for tissue engineering. The aim of our study was to determine whether the AM enables the formation of a normal urinary bladder epithelium-urothelium--and to reveal any differences in the urothelial cell (UC) growth and differentiation when using different AM scaffolds. Cryopreserved human AM was used as a scaffold in three different ways. Normal porcine UCs were seeded on the AM epithelium (eAM), denuded AM (dAM), and stromal AM (sAM) and were cultured for 3 weeks. UC growth on AM scaffolds was monitored daily. By using electron microscopy, histochemical and immunofluorescence techniques, we here provide evidence that all three AM scaffolds enable the development of the urothelium. The fastest growth and the highest differentiation of UCs were demonstrated on the sAM scaffold, which enables the development of tissue-engineered urothelium with molecular and ultrastructural properties comparable to that of the native urothelium. Most importantly, the highly differentiated urothelia on the sAM scaffolds provide important experimental models for future drug delivery studies and developing tissue engineering strategies considering that subtle differences are identified before translation to the clinical settings.

Mathematical modeling of the crack growth in linear elastic isotropic materials by conventional fracture mechanics approaches and by molecular dynamics method: crack propagation direction angle under mixed mode loading

NASA Astrophysics Data System (ADS)

Stepanova, Larisa; Bronnikov, Sergej

2018-03-01

The crack growth directional angles in the isotropic linear elastic plane with the central crack under mixed-mode loading conditions for the full range of the mixity parameter are found. Two fracture criteria of traditional linear fracture mechanics (maximum tangential stress and minimum strain energy density criteria) are used. Atomistic simulations of the central crack growth process in an infinite plane medium under mixed-mode loading using Large-scale Molecular Massively Parallel Simulator (LAMMPS), a classical molecular dynamics code, are performed. The inter-atomic potential used in this investigation is Embedded Atom Method (EAM) potential. The plane specimens with initial central crack were subjected to Mixed-Mode loadings. The simulation cell contains 400000 atoms. The crack propagation direction angles under different values of the mixity parameter in a wide range of values from pure tensile loading to pure shear loading in a wide diapason of temperatures (from 0.1 К to 800 К) are obtained and analyzed. It is shown that the crack propagation direction angles obtained by molecular dynamics method coincide with the crack propagation direction angles given by the multi-parameter fracture criteria based on the strain energy density and the multi-parameter description of the crack-tip fields.

Quantitative ENT endoscopy: the future in the new millennium

NASA Astrophysics Data System (ADS)

Mueller, Andreas; Schubert, Mario

1999-06-01

In Otorhinolaryngology the endoscopic appraisal of luminal dimensions of the nose, the throat, the larynx and the trachea is a daily problem. Those concerned with endoscopy know, that endoscopes distort dimensions of examined anatomical structures. To draw conclusions on luminal dimensions from the endoscopic pictures additional measuring devices are required. We developed a new method of measuring luminal dimensions in rigid or flexible endoscopy. For this a laser beam directed radially marks the anatomical lumen of interest in the videoendoscopic vision. The laser ring becomes deformed according to the form of the cavity explored. By keeping the distance defined between the laser ring and the top of the endoscope, the endoscopic video image can be measured. A piece of software developed by us calculates from the pictures the cross sectional area as well as the extension of benign or malign stenosis of the cavity explored. The result of the endoscopic measuring procedure can be visualized 3D on a PC-monitor. We are going to demonstrate the result of our clinical experience in different otorhinolaryngological diseases with the new endoscopic measuring kit in comparison to standard endoscopy. A further perspective is the endoscopic measuring kit in comparison to standard endoscopy. A further perspective is the endoscopic assisted manufacturing (EAM) of anatomical adapted stents, tubes and cannules.

An Enhanced Adaptive Management Approach for Remediation of Legacy Mercury in the South River

PubMed Central

Foran, Christy M.; Baker, Kelsie M.; Grosso, Nancy R.; Linkov, Igor

2015-01-01

Uncertainties about future conditions and the effects of chosen actions, as well as increasing resource scarcity, have been driving forces in the utilization of adaptive management strategies. However, many applications of adaptive management have been criticized for a number of shortcomings, including a limited ability to learn from actions and a lack of consideration of stakeholder objectives. To address these criticisms, we supplement existing adaptive management approaches with a decision-analytical approach that first informs the initial selection of management alternatives and then allows for periodic re-evaluation or phased implementation of management alternatives based on monitoring information and incorporation of stakeholder values. We describe the application of this enhanced adaptive management (EAM) framework to compare remedial alternatives for mercury in the South River, based on an understanding of the loading and behavior of mercury in the South River near Waynesboro, VA. The outcomes show that the ranking of remedial alternatives is influenced by uncertainty in the mercury loading model, by the relative importance placed on different criteria, and by cost estimates. The process itself demonstrates that a decision model can link project performance criteria, decision-maker preferences, environmental models, and short- and long-term monitoring information with management choices to help shape a remediation approach that provides useful information for adaptive, incremental implementation. PMID:25665032

Atomistic Modeling of Diffusion and Phase Transformations in Metals and Alloys

NASA Astrophysics Data System (ADS)

Purja Pun, Ganga Prasad

Dissertation consists of multiple works. The first part is devoted to self-diffusion along dislocation cores in aluminum followed by the development of embedded atom method potentials for Co, NiAl, CoAl and CoNi systems. The last part focuses on martensitic phase transformation (MPT) in Ni xAl1--x and Al xCoyNi1-- x--y alloys. New calculation methods were developed to predict diffusion coefficients in metal as functions of temperature. Self-diffusion along screw and edge dislocations in aluminum was studied by molecular dynamic (MD) simulations. Three types of simulations were performed with and without (intrinsic) pre-existing vacancies and interstitials in the dislocation core. We found that the diffusion along the screw dislocation was dominated by the intrinsic mechanism, whereas the diffusion along the edge dislocation was dominated by the vacancy mechanism. The diffusion along the screw dislocation was found to be significantly faster than the diffusion along the edge dislocation, and the both diffusivities were in reasonable agreement with experimental data. The intrinsic diffusion mechanism can be associated with the formation of dynamic Frenkel pairs, possibly activated by thermal jogs and/or kinks. The simulations show that at high temperatures the dislocation core becomes an effective source/sink of point defects and the effect of pre-existing defects on the core diffusivity diminishes. First and the foremost ingredient needed in all atomistic computer simulations is the description of interaction between atoms. Interatomic potentials for Co, NiAl, CoAl and CoNi systems were developed within the Embedded Atom Method (EAM) formalism. The binary potentials were based on previously developed accurate potentials for pure Ni and pure Al and pure Co developed in this work. The binaries constitute a version of EAM potential of AlCoNi ternary system. The NiAl potential accurately reproduces a variety of physical properties of the B2-NiAl and L12--Ni3Al phases. The potential is expected to be especially suitable for simulations of hetero-phase interfaces and mechanical behavior of NiAl alloys. Apart from properties of the HCP Co, the new Co potential is accurate enough to reproduce several properties of the FCC Co which were not included in the potential fit. It shows good transferability property. The CoAl potential was fitted to the properties of B2-CoAl phase as in the NiAl fitting where as the NiCo potential was fitted to the ab initio formation energies of some imaginary phases and structures. Effect of chemical composition and uniaxial mechanical stresses was studied on the martensitic phase transformation in B2 type Ni-rich NiAl and AlCoNi alloys. The martensitic phase has a tetragonal crystal structure and can contain multiple twins arranged in domains and plates. The twinned martensites were always formed under the uniaxial compression where as the single variant martensites were the results of the uniaxial tension. The transformation was reversible and characterized by a significant temperature hysteresis. The magnitude of the hysteresis depends on the chemical composition and stress.

Evidence-based algorithm for diagnosis and assessment in psoriatic arthritis: results by Italian DElphi in psoriatic Arthritis (IDEA).

PubMed

Lapadula, G; Marchesoni, A; Salaffi, F; Ramonda, R; Salvarani, C; Punzi, L; Costa, L; Caso, F; Simone, D; Baiocchi, G; Scioscia, C; Di Carlo, M; Scarpa, R; Ferraccioli, G

2016-12-16

Psoriatic arthritis (PsA) is a chronic inflammatory disease involving skin, peripheral joints, entheses, and axial skeleton. The disease is frequently associated with extrarticular manifestations (EAMs) and comorbidities. In order to create a protocol for PsA diagnosis and global assessment of patients with an algorithm based on anamnestic, clinical, laboratory and imaging procedures, we established a DElphi study on a national scale, named Italian DElphi in psoriatic Arthritis (IDEA). After a literature search, a Delphi poll, involving 52 rheumatologists, was performed. On the basis of the literature search, 202 potential items were identified. The steering committee planned at least two Delphi rounds. In the first Delphi round, the experts judged each of the 202 items using a score ranging from 1 to 9 based on its increasing clinical relevance. The questions posed to experts were How relevant is this procedure/observation/sign/symptom for assessment of a psoriatic arthritis patient? Proposals of additional items, not included in the questionnaire, were also encouraged. The results of the poll were discussed by the Steering Committee, which evaluated the necessity for removing selected procedures or adding additional ones, according to criteria of clinical appropriateness and sustainability. A total of 43 recommended diagnosis and assessment procedures, recognized as items, were derived by combination of the Delphi survey and two National Expert Meetings, and grouped in different areas. Favourable opinion was reached in 100% of cases for several aspects covering the following areas: medical (familial and personal) history, physical evaluation, imaging tool, second level laboratory tests, disease activity measurement and extrarticular manifestations. After performing PsA diagnosis, identification of specific disease activity scores and clinimetric approaches were suggested for assessing the different clinical subsets. Further, results showed the need for investigation on the presence of several EAMs and risk factors. In the context of any area, a rank was assigned for each item by Expert Committee members, in order to create the logical sequence of the algorithm. The final list of recommended diagnosis and assessment procedures, by the Delphi survey and the two National Expert Meetings, was also reported as an algorithm. This study shows results obtained by the combination of a DElphi survey of a group of Italian rheumatologists and two National Expert Meetings, created with the aim of establishing a clinical procedure and algorithm for the diagnosis and the assessment of PsA patients. In order to find accurate and practical diagnostic and assessment items in clinical practice, we have focused our attention on evaluating the different PsA domains. Hence, we conceived the IDEA algorithm in order to address PsA diagnosis and assessment in the context of daily clinical practice. The IDEA algorithm might eventually lead to a multidimensional approach and could represent a useful and practical tool for addressing diagnosis and for assessing the disease appropriately. However, the elaborated algorithm needs to be further investigated in daily practice, for evidencing and proving its eventual efficacy in detecting and staging PsA and its heterogeneous spectrum appropriately.

Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Krawczyk, S.; Nawrocka, A.; Zdyb, A.

2018-06-01

The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.

Molecular dynamics study of dual-phase microstructure of Titanium and Zirconium metals during the quenching process

NASA Astrophysics Data System (ADS)

Miyazaki, Narumasa; Sato, Kazunori; Shibutani, Yoji

Dual-phase (DP) transformation, which is composed of felite- and/or martensite- multicomponent microstructural phases, is one of the most effective tools to product functional alloys. To obtain this DP structure such as DP steels and other materials, we usually apply thermal processes such as quenching, tempering and annealing. As the transformation dynamics of DP microstructure depends on conditions of temperature, annealing time, and quenching rate, physical properties of materials are able to be tuned by controlling microstructure type, size, their interfaces and so on. In this study, to understand the behavior of DP transformation and to control physical properties of materials by tuning DP microstructures, we analyze the atomistic dynamics of DP transformation during the quenching process and the detail of DP microstructures by using the molecular dynamics simulations. As target metals of DP transformation, we focus on group 4 transition metals, such as Ti and Zr described by EAM interatomic potentials. For Ti and Zr models we perform molecular dynamics simulations by assuming melt-quenching process from 3000 K to 0 K under the isothermal-isobaric ensemble. During the process for each material, we observe liquid to HCP like transition around the melting temperature, and continuously HCP-BCC like transition around martensitic transformation temperature. Furthermore, we clearly distinguish DP microstructure for each quenched model.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Shenyang; Setyawan, Wahyu; Joshi, Vineet V.

Xe gas bubble superlattice formation is observed in irradiated uranium–10 wt% molybdenum (U10Mo) fuels. However, the thermodynamic properties of the bubbles (the relationship among bubble size, equilibrium Xe concentration, and bubble pressure) and the mechanisms of bubble growth and superlattice formation are not well known. In this work, molecular dynamics is used to study these properties and mechanisms. The results provide important inputs for quantitative mesoscale models of gas bubble evolution and fuel performance. In the molecular dynamics simulations, the embedded-atom method (EAM) potential of U10Mo-Xe (Smirnova et al. 2013) is employed. Initial gas bubbles with low Xe concentration aremore » generated in a U10Mo single crystal. Then Xe atom atoms are continuously added into the bubbles, and the evolution of pressure and dislocation emission around the bubbles is analyzed. The relationship between pressure, equilibrium Xe concentration, and radius of the bubbles is established. It was found that the gas bubble growth is accompanied by partial dislocation emission, which results in a star-shaped dislocation structure and an anisotropic stress field. The emitted partial dislocations have a Burgers vector along the <111> direction and a slip plane of (11-2). Dislocation loop punch-out was not observed. A tensile stress was found along <110> directions around the bubble, favoring the nucleation and formation of a face-centered cubic bubble superlattice in body-centered cubic U10Mo fuels.« less

Transcriptional response of Erwinia amylovora to copper shock: in vivo role of the copA gene.

PubMed

Águila-Clares, Begoña; Castiblanco, Luisa F; Quesada, José Miguel; Penyalver, Ramón; Carbonell, Juan; López, María M; Marco-Noales, Ester; Sundin, George W

2018-01-01

Fire blight is a devastating plant disease caused by the bacterium Erwinia amylovora, and its control is frequently based on the use of copper-based compounds whose mechanisms of action are not well known. Consequently, in this article, we investigate the response of E. amylovora to copper shock by a whole-genome microarray approach. Transcriptional analyses showed that, in the presence of copper, 23 genes were increased in expression; these genes were classified mainly into the transport and stress functional categories. Among them, the copA gene was strongly induced and regulated in a finely tuned manner by copper. Mutation of copA, soxS, arcB, yjcE, ygcF, yhhQ, galF and EAM_3469 genes revealed that tolerance to copper in E. amylovora can be achieved by complex physiological mechanisms, including: (i) the control of copper homeostasis through, at least, the extrusion of Cu(I) by a P-type ATPase efflux pump CopA; and (ii) the overcoming of copper toxicity caused by oxidative stress by the expression of several reactive oxygen species (ROS)-related genes, including the two major transcriptional factors SoxS and ArcB. Furthermore, complementation analyses demonstrated the important role of copA for copper tolerance in E. amylovora, not only in vitro, but also in inoculated pear shoots. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Development of Xe and Kr empirical potentials for CeO 2, ThO 2, UO 2 and PuO 2, combining DFT with high temperature MD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, M. W. D.; Kuganathan, N.; Burr, P. A.

In this study, the development of embedded atom method (EAM) many-body potentials for actinide oxides and associated mixed oxide (MOX) systems has motivated the development of a complementary parameter set for gas-actinide and gas-oxygen interactions. A comprehensive set of density functional theory (DFT) calculations were used to study Xe and Kr incorporation at a number of sites in CeO 2, ThO 2, UO 2 and PuO 2. These structures were used to fit a potential, which was used to generate molecular dynamics (MD) configurations incorporating Xe and Kr at 300 K, 1500 K, 3000 K and 5000 K. Subsequent matchingmore » to the forces predicted by DFT for these MD configurations was used to refine the potential set. This fitting approach ensured weighted fitting to configurations that are thermodynamically significant over a broad temperature range, while avoiding computationally expensive DFT-MD calculations. The resultant gas potentials were validated against DFT trapping energies and are suitable for simulating combinations of Xe and Kr in solid solutions of CeO 2, ThO 2, UO 2 and PuO 2, providing a powerful tool for the atomistic simulation of conventional nuclear reactor fuel UO 2 as well as advanced MOX fuels.« less

Development of Xe and Kr empirical potentials for CeO 2, ThO 2, UO 2 and PuO 2, combining DFT with high temperature MD

DOE PAGES

Cooper, M. W. D.; Kuganathan, N.; Burr, P. A.; ...

2016-08-23

In this study, the development of embedded atom method (EAM) many-body potentials for actinide oxides and associated mixed oxide (MOX) systems has motivated the development of a complementary parameter set for gas-actinide and gas-oxygen interactions. A comprehensive set of density functional theory (DFT) calculations were used to study Xe and Kr incorporation at a number of sites in CeO 2, ThO 2, UO 2 and PuO 2. These structures were used to fit a potential, which was used to generate molecular dynamics (MD) configurations incorporating Xe and Kr at 300 K, 1500 K, 3000 K and 5000 K. Subsequent matchingmore » to the forces predicted by DFT for these MD configurations was used to refine the potential set. This fitting approach ensured weighted fitting to configurations that are thermodynamically significant over a broad temperature range, while avoiding computationally expensive DFT-MD calculations. The resultant gas potentials were validated against DFT trapping energies and are suitable for simulating combinations of Xe and Kr in solid solutions of CeO 2, ThO 2, UO 2 and PuO 2, providing a powerful tool for the atomistic simulation of conventional nuclear reactor fuel UO 2 as well as advanced MOX fuels.« less

MD modeling of screw dislocation influence upon initiation and mechanism of BCC-HCP polymorphous transition in iron

NASA Astrophysics Data System (ADS)

Dremov, V. V.; Ionov, G. V.; Sapozhnikov, F. A.; Smirnov, N. A.; Karavaev, A. V.; Vorobyova, M. A.; Ryzhkov, M. V.

2015-09-01

The present work is devoted to classical molecular dynamics investigation into microscopic mechanisms of the bcc-hcp transition in iron. The interatomic potential of EAM type used in the calculations was tested for the capability to reproduce ab initio data on energy evolution along the bcc-hcp transformation path (Burgers deformation + shuffe) and then used in the large-scale MD simulations. The large-scale simulations included constant volume deformation along the Burgers path to study the origin and nature of the plasticity, hydrostatic volume compression of defect free samples above the bcc to hcp transition threshold to observe the formation of new phase embryos, and the volume compression of samples containing screw dislocations to study the effect of the dislocations on the probability of the new phase critical embryo formation. The volume compression demonstrated high level of metastability. The transition starts at pressure much higher than the equilibrium one. Dislocations strongly affect the probability of the critical embryo formation and significantly reduce the onset pressure of transition. The dislocations affect also the resulting structure of the samples upon the transition. The formation of layered structure is typical for the samples containing the dislocations. The results of the simulations were compared with the in-situ experimental data on the mechanism of the bcc-hcp transition in iron.

Effective Acceleration Model for the Arrival Time of Interplanetary Shocks driven by Coronal Mass Ejections

NASA Astrophysics Data System (ADS)

Paouris, Evangelos; Mavromichalaki, Helen

2017-12-01

In a previous work (Paouris and Mavromichalaki in Solar Phys. 292, 30, 2017), we presented a total of 266 interplanetary coronal mass ejections (ICMEs) with as much information as possible. We developed a new empirical model for estimating the acceleration of these events in the interplanetary medium from this analysis. In this work, we present a new approach on the effective acceleration model (EAM) for predicting the arrival time of the shock that preceds a CME, using data of a total of 214 ICMEs. For the first time, the projection effects of the linear speed of CMEs are taken into account in this empirical model, which significantly improves the prediction of the arrival time of the shock. In particular, the mean value of the time difference between the observed time of the shock and the predicted time was equal to +3.03 hours with a mean absolute error (MAE) of 18.58 hours and a root mean squared error (RMSE) of 22.47 hours. After the improvement of this model, the mean value of the time difference is decreased to -0.28 hours with an MAE of 17.65 hours and an RMSE of 21.55 hours. This improved version was applied to a set of three recent Earth-directed CMEs reported in May, June, and July of 2017, and we compare our results with the values predicted by other related models.

Dislocation and Structural Studies at Metal-Metallic Glass Interface at Low Temperature

NASA Astrophysics Data System (ADS)

Gupta, Pradeep; Yedla, Natraj

2017-12-01

In this paper, molecular dynamics (MD) simulation deformation studies on the Al (metal)-Cu50Zr50 (metallic glass) model interface is carried out based on cohesive zone model. The interface is subjected to mode-I loading at a strain rate of 109 s-1 and temperature of 100 K. The dislocations reactions and evolution of dislocation densities during the deformation have been investigated. Atomic interactions between Al, Cu and Zr atoms are modeled using EAM (embedded atom method) potential, and a timestep of 0.002 ps is used for performing the MD simulations. A circular crack and rectangular notch are introduced at the interface to investigate the effect on the deformation behavior and fracture. Further, scale size effect is also investigated. The structural changes and evolution of dislocation density are also examined. It is found that the dominant deformation mechanism is by Shockley partial dislocation nucleation. Amorphization is observed in the Al regions close to the interface and occurs at a lower strain in the presence of a crack. The total dislocation density is found to be maximum after the first yield in both the perfect and defect interface models and is highest in the case of perfect interface with a density of 6.31 × 1017 m-2. In the perfect and circular crack defect interface models, it is observed that the fraction of Shockley partial dislocation density decreases, whereas that of strain rod dislocations increases with increase in strain.

Early Patient Access to Medicines: Health Technology Assessment Bodies Need to Catch Up with New Marketing Authorization Methods.

PubMed

Leyens, Lada; Brand, Angela

National and international medicines agencies have developed innovative methods to expedite promising new medicines to the market and facilitate early patient access. Some of these approval pathways are the conditional approval and the adaptive pathways by the European Medicines Agency (EMA); the Promising Innovative Medicine (PIM) designation and the Early Access to Medicines Scheme (EAMS) by the Medicines and Healthcare Products Regulatory Agency (MHRA), as well as the Fast Track, Breakthrough or Accelerated Approval methods by the Food and Drug Administration (FDA). However, at least in Europe, these methods cannot achieve the goal of improving timely access for patients to new medicines on their own; the reimbursement process also has to become adaptive and flexible. In the past 2 years, the effective access (national patient access) to newly approved oncology drugs ranged from 1 to 30 months, with an extremely high variability between European countries. The goal of early patient access in Europe can only be achieved if the national health technology assessment bodies, such as NICE (ENG), HAS (FR), G-BA (DE) or AIFA (IT), provide harmonized, transparent, flexible, conditional and adaptive methods that adopt the level of evidence accepted by the medicines agencies. The efforts from medicines agencies are welcome but will be in vain if health technology assessments do not follow with similar initiatives, and the European 'postcode' lottery will continue. © 2016 S. Karger AG, Basel.

Qualitative assessment of climate-driven ecological shifts in the Caspian Sea

PubMed Central

Beyraghdar Kashkooli, Omid; Gröger, Joachim; Núñez-Riboni, Ismael

2017-01-01

The worldwide occurrence of complex climate-induced ecological shifts in marine systems is one of the major challenges in sustainable bio-resources management. The occurrence of ecological environment-driven shifts was studied in the Southern Caspian Sea using the “shiftogram” method on available fisheries-related (i.e. commercially important bentho-pelagic fish stocks) ecological and climatic variables. As indicators of potential environmentally driven shift patterns we used indices for the North Atlantic Oscillation, the Southern Oscillation, the Siberian High, the East Atlantic-West Russia pattern, as well as Sea Surface Temperature and surface chlorophyll-a concentration. Given the explorative findings from the serial shift analyses, the cascading and serial order of multiple shift events in climatic-ecologic conditions of the southern Caspian Sea suggested a linkage between external forces and dynamics of ecosystem components and structures in the following order: global-scale climate forces lead to local environmental processes, which in turn lead to biological components dynamics. For the first time, this study indicates that ecological shifts are an integral component of bentho-pelagic subsystem regulatory processes and dynamics. Qualitative correspondence of biological responses of bentho-pelagic stocks to climatic events is one of the supporting evidences that overall Caspian ecosystem structures and functioning might have–at least partially–been impacted by global-scale climatic or local environmental shifts. These findings may help to foster a regional Ecosystem-based Approach to Management (EAM) as an integral part of bentho-pelagic fisheries management plans. PMID:28475609

Influence of pendant chiral C(γ)-(alkylideneamino/guanidino) cationic side-chains of PNA backbone on hybridization with complementary DNA/RNA and cell permeability.

PubMed

Jain, Deepak R; Anandi V, Libi; Lahiri, Mayurika; Ganesh, Krishna N

2014-10-17

Intrinsically cationic and chiral C(γ)-substituted peptide nucleic acid (PNA) analogues have been synthesized in the form of γ(S)-ethyleneamino (eam)- and γ(S)-ethyleneguanidino (egd)-PNA with two carbon spacers from the backbone. The relative stabilization (ΔTm) of duplexes from modified cationic PNAs as compared to 2-aminoethylglycyl (aeg)-PNA is better with complementary DNA (PNA:DNA) than with complementary RNA (PNA:RNA). Inherently, PNA:RNA duplexes have higher stability than PNA:DNA duplexes, and the guanidino PNAs are superior to amino PNAs. The cationic PNAs were found to be specific toward their complementary DNA target as seen from their significantly lower binding with DNA having single base mismatch. The differential binding avidity of cationic PNAs was assessed by the displacement of DNA duplex intercalated ethidium bromide and gel electrophoresis. The live cell imaging of amino/guanidino PNAs demonstrated their ability to penetrate the cell membrane in 3T3 and MCF-7 cells, and cationic PNAs were found to be accumulated in the vicinity of the nuclear membrane in the cytoplasm. Fluorescence-activated cell sorter (FACS) analysis of cell permeability showed the efficiency to be dependent upon the nature of cationic functional group, with guanidino PNAs being better than the amino PNAs in both cell lines. The results are useful to design new biofunctional cationic PNA analogues that not only bind RNA better but also show improved cell permeability.

Interaction of irradiation-induced prismatic dislocation loops with free surfaces in tungsten

NASA Astrophysics Data System (ADS)

Fikar, Jan; Gröger, Roman; Schäublin, Robin

2017-02-01

The prismatic dislocation loops appear in metals as a result of high-energy irradiation. Understanding their formation and interaction is important for quantification of irradiation-induced deterioration of mechanical properties. Characterization of dislocation loops in thin foils is commonly made using transmission electron microscopy (TEM), but the results are inevitably influenced by the proximity of free surfaces. The prismatic loops are attracted to free surfaces by image forces. Depending on the type, size and depth of the loop in the foil, they can escape to the free surface, thus invalidating TEM observations and conclusions. In this article small prismatic hexagonal and circular dislocation loops in tungsten with the Burgers vectors 1/2 〈 1 1 1 〉 and 〈 1 0 0 〉 are studied by molecular statics simulations using three embedded atom method (EAM) potentials. The calculated image forces are compared to known elastic solutions. A particular attention is paid to the critical stress to move edge dislocations. The escape of the loop to the free surface is quantified by a combination of atomistic simulations and elastic calculations. For example, for the 1/2 〈 1 1 1 〉 loop with diameter 7.4 nm in a 55 nm thick foil we calculated that about one half of the loops will escape to the free surface. This implies that TEM observations detect only approx. 50% of the loops that were originally present in the foil.

Pharmacological characterization of emerging synthetic cannabinoids in HEK293T cells and hippocampal neurons.

PubMed

Costain, Willard J; Tauskela, Joseph S; Rasquinha, Ingrid; Comas, Tanya; Hewitt, Melissa; Marleau, Vincent; Soo, Evelyn C

2016-09-05

There has been a worldwide proliferation of synthetic cannabinoids that have become marketed as legal alternatives to cannabis (marijuana). Unfortunately, there is a dearth of information about the pharmacological effects of many of these emerging synthetic cannabinoids (ESCs), which presents a challenge for regulatory authorities that need to take such scientific evidence into consideration in order to regulate ECSs as controlled substances. We aimed to characterize the pharmacological properties of ten ESCs using two cell based assays that enabled the determination of potency and efficacy relative to a panel of well-characterized cannabinoids. Agonist-mediated inhibition of forskolin-stimulated cyclic adenosine monophosphate (cAMP) levels was monitored in live HEK293T cells transfected with human cannabinoid receptor 1 gene (CNR1) and pGloSensor-22F. Pharmacological analysis of this data indicated that all of the ESCs tested were full agonists, with the following rank order of potency: Win 55212-2≈5F-PB-22≈AB-PINACA≈EAM-2201≈MAM-2201>JWH-250≈ PB-22>AKB48 N-(5FP)>AKB-48≈STS-135>XLR-11. Assessment of agonist-stimulated depression of Ca(2+) transients was also used to confirm the efficacy of five ESCs (XLR-11, JWH-250, AB-PINACA, 5F-PB-22, and MAM-2201) in cultured primary hippocampal neurons. This work aims to help inform decisions made by regulatory agencies concerned with the profusion of these poorly characterized recreational drugs. Copyright © 2016. Published by Elsevier B.V.

An improved interatomic potential for xenon in UO2: a combined density functional theory/genetic algorithm approach.

PubMed

Thompson, Alexander E; Meredig, Bryce; Wolverton, C

2014-03-12

We have created an improved xenon interatomic potential for use with existing UO2 potentials. This potential was fit to density functional theory calculations with the Hubbard U correction (DFT + U) using a genetic algorithm approach called iterative potential refinement (IPR). We examine the defect energetics of the IPR-fitted xenon interatomic potential as well as other, previously published xenon potentials. We compare these potentials to DFT + U derived energetics for a series of xenon defects in a variety of incorporation sites (large, intermediate, and small vacant sites). We find the existing xenon potentials overestimate the energy needed to add a xenon atom to a wide set of defect sites representing a range of incorporation sites, including failing to correctly rank the energetics of the small incorporation site defects (xenon in an interstitial and xenon in a uranium site neighboring uranium in an interstitial). These failures are due to problematic descriptions of Xe-O and/or Xe-U interactions of the previous xenon potentials. These failures are corrected by our newly created xenon potential: our IPR-generated potential gives good agreement with DFT + U calculations to which it was not fitted, such as xenon in an interstitial (small incorporation site) and xenon in a double Schottky defect cluster (large incorporation site). Finally, we note that IPR is very flexible and can be applied to a wide variety of potential forms and materials systems, including metals and EAM potentials.

A unified description of the electrochemical, charge distribution, and spectroscopic properties of the special-pair radical cation in bacterial photosynthesis.

PubMed

Reimers, Jeffrey R; Hush, Noel S

2004-04-07

We apply our four-state 70-vibration vibronic-coupling model for the properties of the photosynthetic special-pair radical cation to: (1) interpret the observed correlations between the midpoint potential and the distribution of spin density between the two bacteriochlorophylls for 30 mutants of Rhodobacter sphaeroides, (2) interpret the observed average intervalence hole-transfer absorption energies as a function of spin density for six mutants, and (3) simulate the recently obtained intervalence electroabsorption Stark spectrum of the wild-type reaction center. While three new parameters describing the location of the sites of mutation with respect to the special pair are required to describe the midpoint-potential data, a priori predictions are made for the transition energies and the Stark spectrum. In general, excellent predictions are made of the observed quantities, with deviations being typically of the order of twice the experimental uncertainties. A unified description of many chemical and spectroscopic properties of the bacterial reaction center is thus provided. Central to the analysis is the assumption that the perturbations made to the reaction center, either via mutations of protein residues or by application of an external electric field, act only to independently modify the oxidation potentials of the two halves of the special pair and hence the redox asymmetry E0. While this appears to be a good approximation, clear evidence is presented that effects of mutation can be more extensive than what is allowed for. A thorough set of analytical equations describing the observed properties is obtained using the Born-Oppenheimer adiabatic approximation. These equations are generally appropriate for intervalence charge-transfer problems and include, for the first time, full treatment of both symmetric and antisymmetric vibrational motions. The limits of validity of the adiabatic approach to the full nonadiabatic problem are obtained.

Growth of bacterial phytopathogens in animal manures.

PubMed

Sledz, Wojciech; Zoledowska, Sabina; Motyka, Agata; Kadziński, Leszek; Banecki, Bogdan

2017-01-01

Animal manures are routinely applied to agricultural lands to improve crop yield, but the possibility to spread bacterial phytopathogens through field fertilization has not been considered yet. We monitored 49 cattle, horse, swine, sheep or chicken manure samples collected in 14 Polish voivodeships for the most important plant pathogenic bacteria - Ralstonia solanacearum (Rsol), Xanthomonas campestris pv. campestris (Xcc), Pectobacterium carotovorum subsp. carotovorum (Pcc), Pectobacterium atrosepticum (Pba), Erwinia amylovora (Eam), Clavibacter michiganensis subsp. sepedonicus (Cms) and Dickeya sp. (Dsp). All of the tested animal fertilizers were free of these pathogens. Subsequently, the growth dynamics of Pba, Pcc, Rsol, and Xcc in cattle, horse, swine, sheep and chicken manures sterilized either by autoclaving or filtration was evaluated. The investigated phytopathogens did not exhibit any growth in the poultry manure. However, the manure filtrates originating from other animals were suitable for microbial growth, which resulted in the optical density change of 0.03-0.22 reached within 26 h (48 h Rsol, 120 h Xcc), depending on bacterial species and the manure source. Pcc and Pba multiplied most efficiently in the cattle manure filtrate. These bacteria grew faster than Rsol and Xcc in all the tested manure samples, both the filtrates and the autoclaved semi-solid ones. Though the growth dynamics of investigated strains in different animal fertilizers was unequal, all of the tested bacterial plant pathogens were proven to use cattle, horse, swine and sheep manures as the sources of nutrients. These findings may contribute to further research on the alternative routes of spread of bacterial phytopathogens, especially because of the fact that the control of pectionolytic bacteria is only based on preventive methods.

Permanent-Magnet Free Biasing of MR Sensors with Tunable Sensitivity

NASA Astrophysics Data System (ADS)

Halloran, Sean; Dasilva, Fabio; Pappas, David

2007-03-01

Exchange coupling^1 has been previously observed in a trilayer structure of ferromagnet (FM)/non-magnetic/antiferromagnet (AFM) and the exchange bias was found to be a function of the thickness of the buffer layer.^2,3,4 This unique coupling is used as a stabilizing bias for the sense layer with the additional ability to tailor the magnetic gain of the sensor for various applications. The elimination of permanent magnet bias results in the elimination of one patterning and one deposition step. Ruthenium (Ru) is used as the buffer layer and is self aligned with the FM and AFM layers and the thickness is varied to change the slope of the transfer curve in the linear region. Sensor devices are fabricated with a bipolar output, a medium sensitivity, and a wide field range. The results show that this biasing scheme is well suited for barber pole and soft adjacent layer (SAL) anisotropic magnetoresistance (AMR) stripes used in magnetic field sensors with a FM layer of Permalloy (NiFe) and an AFM layer of Iridium-Manganese (IrMn). Applications include a 256 channel read head used for magnetic forensics. 1N.J. Gokemeijer, T. Ambrose, C.L. Chien, N. Wang and K.K. Fung, J. Appl. Phys. 81 (8), 4999, 15 April 1997. 2W.H. Meiklejohn and C.P. Bean, Phys. Rev. 102, 1413 1956; 105, 904, 1957. 3L. Thomas, A.J. Kellock and S.S.P. Parkin, J. Appl. Phys. 87 (9), 5061, 1 May 2000. 4D. Wang, J. Daughton, C. Nordman, P. Eames and J. Fink, J. Appl. Phys. 99, 2006.

Effects of cottonseed meal supplementation time on ruminal fermentation and forage intake by Holstein steers fed fescue hay.

PubMed

Judkins, M B; Krysl, L J; Barton, R K; Holcombe, D W; Gunter, S A; Broesder, J T

1991-09-01

Four ruminally cannulated Holstein steers (average BW 303 kg) were used in a 4 x 4 Latin square design digestion trial to study the influence of daily cottonseed meal (CSM; 1.6 g of CP/kg of BW) supplementation time on forage intake and ruminal fluid kinetics and fermentation. Steers were housed individually in tie stalls and were fed chopped fescue hay on an ad libitum basis at 0600 and 1400. Treatments were 1) control, grass hay only (CON) and grass hay and CSM fed once daily at 2) 0600 (EAM) 3) 1000 (MAM), or 4) 1400 (PM). Ruminal NH3 N concentrations reflected a time of supplementation x sampling time interaction (P less than .05); CON steers had the lowest (P less than .05) ruminal NH3 N concentrations at all times other than at 0600, 1000, 1200, and 2400, when they did not differ (P greater than .05) from at least one of the supplemented groups. Forage intake, ratio of bacterial purine:N, rate of DM and NDF disappearance, and ruminal fluid kinetics were not influenced (P greater than .05) by supplementation time. Total ruminal VFA differed (P less than .05) between CON and supplemented steers, as well as among supplemented steers (linear and quadratic effects P less than .05). Acetate, propionate, and valerate proportions were influenced (P less than .05) by a sampling time X supplementation time interaction. Under the conditions of this study, greater peak ammonia concentrations with morning supplementation than with afternoon supplementation did not stimulate ruminal fermentation or rate of NDF disappearance.

Assessment of types of synthetic cannabinoids in narcotic cases assessed by the Council of Forensic Medicine between 2011-2015, Ankara, Turkey.

PubMed

Göl, Ersin; Çok, İsmet

2017-11-01

Synthetic cannabinoids mimic the effects of cannabis and are the largest and fastest growing class of newly appearing designer drugs. Reports have revealed that various types of synthetic cannabinoids are mixed with herbal substances. The present study investigated the herbal substance cases involving synthetic cannabinoids in Ankara and nearby cities in Turkey. Data were collected from the reports of synthetic cannabinoids that were analyzed between January 01, 2011 and December 31, 2015 in the Ankara Narcotic Department of the Council of Forensic Medicine at the request of the judicial authorities. In all, 4610 narcotic reports were obtained and reviewed. Among these narcotic reports during the period, 370 reports (8%) were related to synthetic cannabinoids. 28 synthetic cannabinoid compounds could be identified in herbals: 5-F-AB-PINACA, 5-F-AKB-48, 5-F-NNEI, 5-F-PB-22, AB-CHMINACA, AB-FUBINACA, AB-PINACA, ADB-CHMINACA, ADB-FUBINACA, AKB-48, AM-2201, EAM-2201, JWH-018, JWH-022, JWH-031, JWH-122, JWH-201, JWH-210, JWH-250, JWH-251, JWH-307, MAM-2201, NM-2201, PB-22, RCS-4, THJ-2201, UR-144, XLR-11. The amount of herbals was 30.72g, 329.22g, 665.89g, 4844.7g, and 5684.3g in 2011, 2012, 2013, 2014, and 2015, respectively. Generally, herbals contained more than one synthetic cannabinoids. ADB-FUBINACA was the most common synthetic cannabinoid among the herbals determined in this study, which was 3132.43g, excepting multi-synthetic cannabinoid herbals. The amount and diversity of synthetic cannabinoid compounds have increased dramatically between 2011 and 2015. Copyright © 2017 Elsevier B.V. All rights reserved.

Multilaboratory Validation of First Action Method 2016.04 for Determination of Four Arsenic Species in Fruit Juice by High-Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry.

PubMed

Kubachka, Kevin; Heitkemper, Douglas T; Conklin, Sean

2017-07-01

Before being designated AOAC First Action Official MethodSM 2016.04, the U.S. Food and Drug Administration's method, EAM 4.10 High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometric Determination of Four Arsenic Species in Fruit Juice, underwent both a single-laboratory validation and a multilaboratory validation (MLV) study. Three federal and five state regulatory laboratories participated in the MLV study, which is the primary focus of this manuscript. The method was validated for inorganic arsenic (iAs) measured as the sum of the two iAs species arsenite [As(III)] and arsenate [As(V)], dimethylarsinic acid (DMA), and monomethylarsonic acid (MMA) by analyses of 13 juice samples, including three apple juice, three apple juice concentrate, four grape juice, and three pear juice samples. In addition, two water Standard Reference Materials (SRMs) were analyzed. The method LODs and LOQs obtained among the eight laboratories were approximately 0.3 and 2 ng/g, respectively, for each of the analytes and were adequate for the intended purpose of the method. Each laboratory analyzed method blanks, fortified method blanks, reference materials, triplicate portions of each juice sample, and duplicate fortified juice samples (one for each matrix type) at three fortification levels. In general, repeatability and reproducibility of the method was ≤15% RSD for each species present at a concentration >LOQ. The average recovery of fortified analytes for all laboratories ranged from 98 to 104% iAs, DMA, and MMA for all four juice sample matrixes. The average iAs results for SRMs 1640a and 1643e agreed within the range of 96-98% of certified values for total arsenic.

Phonon optimized interatomic potential for aluminum

NASA Astrophysics Data System (ADS)

Muraleedharan, Murali Gopal; Rohskopf, Andrew; Yang, Vigor; Henry, Asegun

2017-12-01

We address the problem of generating a phonon optimized interatomic potential (POP) for aluminum. The POP methodology, which has already been shown to work for semiconductors such as silicon and germanium, uses an evolutionary strategy based on a genetic algorithm (GA) to optimize the free parameters in an empirical interatomic potential (EIP). For aluminum, we used the Vashishta functional form. The training data set was generated ab initio, consisting of forces, energy vs. volume, stresses, and harmonic and cubic force constants obtained from density functional theory (DFT) calculations. Existing potentials for aluminum, such as the embedded atom method (EAM) and charge-optimized many-body (COMB3) potential, show larger errors when the EIP forces are compared with those predicted by DFT, and thus they are not particularly well suited for reproducing phonon properties. Using a comprehensive Vashishta functional form, which involves short and long-ranged interactions, as well as three-body terms, we were able to better capture interactions that reproduce phonon properties accurately. Furthermore, the Vashishta potential is flexible enough to be extended to Al2O3 and the interface between Al-Al2O3, which is technologically important for combustion of solid Al nano powders. The POP developed here is tested for accuracy by comparing phonon thermal conductivity accumulation plots, density of states, and dispersion relations with DFT results. It is shown to perform well in molecular dynamics (MD) simulations as well, where the phonon thermal conductivity is calculated via the Green-Kubo relation. The results are within 10% of the values obtained by solving the Boltzmann transport equation (BTE), employing Fermi's Golden Rule to predict the phonon-phonon relaxation times.

High Strain Rate and Shock-Induced Deformation in Metals

NASA Astrophysics Data System (ADS)

Ravelo, Ramon

2012-02-01

Large-scale non-equilibrium molecular Dynamics (MD) simulations are now commonly used to study material deformation at high strain rates (10^9-10^12 s-1). They can provide detailed information-- such as defect morphology, dislocation densities, and temperature and stress profiles, unavailable or hard to measure experimentally. Computational studies of shock-induced plasticity and melting in fcc and bcc single, mono-crystal metals, exhibit generic characteristics: high elastic limits, large directional anisotropies in the yield stress and pre-melting much below the equilibrium melt temperature for shock wave propagation along specific crystallographic directions. These generic features in the response of single crystals subjected to high strain rates of deformation can be explained from the changes in the energy landscape of the uniaxially compressed crystal lattice. For time scales relevant to dynamic shock loading, the directional-dependence of the yield strength in single crystals is shown to be due to the onset of instabilities in elastic-wave propagation velocities. The elastic-plastic transition threshold can accurately be predicted by a wave-propagation stability analysis. These strain-induced instabilities create incipient defect structures, which can be quite different from the ones, which characterize the long-time, asymptotic state of the compressed solid. With increase compression and strain rate, plastic deformation via extended defects gives way to amorphization associated with the loss in shear rigidity along specific deformation paths. The hot amorphous or (super-cooled liquid) metal re-crystallizes at rates, which depend on the temperature difference between the amorphous solid and the equilibrium melt line. This plastic-amorphous transition threshold can be computed from shear-waves stability analyses. Examples from selected fcc and bcc metals will be presented employing semi-empirical potentials of the embedded atom method (EAM) type as well as results from density functional theory calculations.

Carbon diffusion paths and segregation at high-angle tilt grain boundaries in α-Fe studied by using a kinetic activation-relation technique

NASA Astrophysics Data System (ADS)

Restrepo, Oscar A.; Mousseau, Normand; Trochet, Mickaël; El-Mellouhi, Fedwa; Bouhali, Othmane; Becquart, Charlotte S.

2018-02-01

Carbon diffusion and segregation in iron is fundamental to steel production but is also associated with corrosion. Using the kinetic activation-relaxation technique (k-ART), a kinetic Monte Carlo (KMC) algorithm with an on-the-fly catalog that allows to obtain diffusion properties over large time scales taking into account long-range elastic effects coupled with an EAM force field, we study the motion of a carbon impurity in four Fe systems with high-angle grain boundaries (GB), focusing on the impact of these extended defects on the long-time diffusion of C. Short and long-time stability of the various GBs is first analyzed, which allows us to conclude that the Σ 3 (1 1 1 ) θ =109 .53∘<110 > GB is unstable, with Fe migration barriers of ˜0.1 eV or less, and C acts as a pinning center. Focusing on three stable GBs, in all cases, these extended defects trap C in energy states lower than found in the crystal. Yet, contrary to general understanding, we show, through simulations extending to 0.1 s, that even tough C diffusion takes place predominantly in the GB, it is not necessarily faster than in the bulk and can even be slower by one to two orders of magnitude depending on the GB type. Analysis of the energy landscape provided by k-ART also shows that the free cavity volume around the impurity is not a strong predictor of diffusion barrier height. Overall, results show rather complex diffusion kinetics intimately dependent on the local environment.

Conformational Fluctuations in G-Protein-Coupled Receptors

NASA Astrophysics Data System (ADS)

Brown, Michael F.

2014-03-01

G-protein-coupled receptors (GPCRs) comprise almost 50% of pharmaceutical drug targets, where rhodopsin is an important prototype and occurs naturally in a lipid membrane. Rhodopsin photoactivation entails 11-cis to all-trans isomerization of the retinal cofactor, yielding an equilibrium between inactive Meta-I and active Meta-II states. Two important questions are: (1) Is rhodopsin is a simple two-state switch? Or (2) does isomerization of retinal unlock an activated conformational ensemble? For an ensemble-based activation mechanism (EAM) a role for conformational fluctuations is clearly indicated. Solid-state NMR data together with theoretical molecular dynamics (MD) simulations detect increased local mobility of retinal after light activation. Resultant changes in local dynamics of the cofactor initiate large-scale fluctuations of transmembrane helices that expose recognition sites for the signal-transducing G-protein. Time-resolved FTIR studies and electronic spectroscopy further show the conformational ensemble is strongly biased by the membrane lipid composition, as well as pH and osmotic pressure. A new flexible surface model (FSM) describes how the curvature stress field of the membrane governs the energetics of active rhodopsin, due to the spontaneous monolayer curvature of the lipids. Furthermore, influences of osmotic pressure dictate that a large number of bulk water molecules are implicated in rhodopsin activation. Around 60 bulk water molecules activate rhodopsin, which is much larger than the number of structural waters seen in X-ray crystallography, or inferred from studies of bulk hydrostatic pressure. Conformational selection and promoting vibrational motions of rhodopsin lead to activation of the G-protein (transducin). Our biophysical data give a paradigm shift in understanding GPCR activation. The new view is: dynamics and conformational fluctuations involve an ensemble of substates that activate the cognate G-protein in the amplified visual response.

The validation and preference among different EAM potentials to describe the solid-liquid transition of aluminum

NASA Astrophysics Data System (ADS)

Jiang, Yewei; Luo, Jie; Wu, Yongquan

2017-06-01

Empirical potential is vital to the classic atomic simulation, especially for the study of phase transitions, as well as the solid-interface. In this paper, we attempt to set up a uniform procedure for the validation among different potentials before the formal simulation study of phase transitions of metals. Two main steps are involved: (1) the prediction of the structures of both solid and liquid phases and their mutual transitions, i.e. melting and crystallization; (2) the prediction of vital thermodynamic (the equilibrium melting point at ambient pressure) and dynamic properties (the degrees of superheating and undercooling). We applied this procedure to the testing of seven published embedded-atom potentials (MKBA (Mendelev et al 2008 Philos. Mag. 88 1723), MFMP (Mishin et al 1999 Phys. Rev. B 59 3393), MDSL (Sturgeon and Laird 2000 Phys. Rev. B 62 14720), ZM (Zope and Mishin 2003 Phys. Rev. B 68 024102), LEA (Liu et al 2004 Model. Simul. Mater. Sci. Eng. 12 665), WKG (Winey et al 2009 Model. Simul. Mater. Sci. Eng. 17 055004) and ZJW (Zhou et al 2004 Phys. Rev. B 69 144113)) for the description of the solid-liquid transition of Al. All the predictions of structure, melting point and superheating/undercooling degrees were compared with the experiments or theoretical calculations. Then, two of them, MKBA and MDSL, were proven suitable for the study of the solid-liquid transition of Al while the residuals were unqualified. However, potential MKBA is more accurate to predict the structures of solid and liquid, while MDSL works a little better in the thermodynamic and dynamic predictions of solid-liquid transitions.

Assessment of contamination and health risk of heavy metals in selected water bodies around gold mining areas in Ghana.

PubMed

Hadzi, George Yaw; Essumang, David Kofi; Ayoko, Godwin A

2018-06-16

Heavy metal contamination of selected rivers in Ghana was studied as part of a bigger project aimed at setting background standard for heavy metals in the Ghanaian environment. Water samples were collected from major mining and eight pristine areas. The samples were acid digested with aqua-regia and analyzed with ICP-MS for As, Cd, Hg, Zn, Cu, Mn, Fe, Cr, Al, V, Co, Ni, and Pb. The average concentrations (mg/L) from the pristine sites ranged from 0.002 ± 0.00(As) to 0.929 ± 0.06 (Fe) and 0.002 ± 0.00 (Pb) to 20.355 ± 5.60 (Fe) from the mining sites. With the exception of Al, Fe, and Mn, the metals level were found to be within the WHO and USEPA guideline limits. Hazard quotients (HQ) for ingestion and dermal contact for pristine and mining samples ranged from 3.00E-04 (Cu) to 0.84 (Cr) and 2.40E-06 (Cu) to 7.44 (As), respectively. The carcinogenic risk (CR) for ingestion and dermal contact ranged from 5.03E-06 to 1.71E-07 (Cr) and 4.22E-08 to 1.44E-09 (Cr), respectively. Arsenic showed a CR value higher than the acceptable limit (1.8E-02) from the mining sites which poses carcinogenic health threat. Multicriteria ranking suggests Birim river (EAM) as the most contaminated. The pattern recognition and multicriteria approach in characterizing the heavy metal contamination (for the first time in the case of Ghana) from the various sites will provide fresh insights into the risk assessment of heavy metals in contaminated surface waters.

Grain Boundary Character Distributions In Isostructural Materials

NASA Astrophysics Data System (ADS)

Ratanaphan, Sutatch

Anisotropic grain boundary character distributions (GBCDs), which influence macroscopic materials properties, are thought to be controlled by the grain boundary energy anisotropy. Structurally, grain boundary could be viewed as two free surfaces joined together. Grain boundary energy could be simply defined by the total excess energy for creating two free surfaces minus the energy gained when new bonds are formed between these surfaces. This implies that different crystal structure should have different GBEDs and GBCDs. It was recently discovered that grain boundary energy distributions (GBED) in isostructural materials, a class of materials that share the same crystal structure, are directly related to one another. This suggests that GBCDs in isostructural materials might also be related in a similar way. To test this hypothesis, electron backscatter diffraction (EBSD) was used to map grain orientations in Ag, Au, Cu, Fe, and Mo. The GBCDs were determined from the stereological interpretation of EBSD maps containing on the order of 100,000 grains. It was found that the GBCDs of face-centered cubic (FCC) metals are statistically correlated, while the GBCDs of body-centered cubic (BCC) Fe and Mo are not correlated to the GBCD of FCC metals. The degree of the correlations among the FCC metals is weaker if there are significant differences in grain shape or texture. For example, Ag has the weakest correlation to the other FCC materials and also has quantitatively different grain shapes and texture. The relationship between the populations and energies of grain boundaries was also studied. By comparing the GBCDs of Al, Au, Cu, and Ni to the energies of 388 grain boundaries previously calculated by the Embedded Atom Method (EAM), we observed a moderately inverse correlation between the relative areas of grain boundaries and their energies. Interestingly, there are strong inverse correlations between the energies and populations of the most common grain boundaries (Sigma3, Sigma9, and Sigma27). Because the enhancement of twin related boundaries due to the prevalence Sigma3 boundaries results in a decrease in the grain boundary populations for the other boundary types, this inverse correlation is influenced by the crystallographic constraints at triple junctions. In other words, having an anisotropic misorientation distribution with strong maxima for certain boundaries biases the inverse correlation between grain boundary population and energy for other boundaries and causes different slopes at each misorientation. Interestingly, the inverse correlation at each misorientation is consistent with the Boltzmann distribution. Based on our results, it is possible to predict the GBCDs and GBEDs in isostructural polycrystalline materials by using a single GBCD and GBED. This principle is demonstrated by predicting the GBCD and GBED of Actinium (Ac). To investigate the GBED in the isostructural BCC metals, the energies of 408 grain boundaries in Fe and Mo were computed using atomistic simulations based on the embedded-atom method (EAM) potential. We found that the calculated boundary energies in Fe and Mo were strongly correlated and scaled with the ratio of the cohesive energy divided by the square of the lattice constant (Ecoh/a02). We would expect that the GBCD of Fe and Mo might be correlated in a similar manner to that of FCC metals. To test this hypothesis, we compared the GBCDs of Fe and Mo. We found that the GBCDs of Fe and Mo are moderately and strongly correlated when all boundary types and only Sigma3 boundaries were considered, respectively. In this thesis, the results demonstrated that the GBCDs of isostructural materials are correlated with one another and the magnitudes of correlation coefficients varied. Reduced correlations were observed when there were differences in the microstructure and crystallographic texture. The inverse relationship between grain boundary population and energy is more strongly correlated at each misorientation than over the entire five macroscopic parameters of grain boundary, especially when there is significant misorientation texture. This relationship leads to GBCDs of isostructural materials that are also more strongly correlated at each misorientation than over the entire grain boundary space.

Diffusion behavior of Cu/Ta heterogeneous interface under high temperature and high strain: An atomistic investigation

NASA Astrophysics Data System (ADS)

Li, Ganglong; Wu, Houya; Luo, Honglong; Chen, Zhuo; Tay, Andrew A. O.; Zhu, Wenhui

2017-09-01

Three-dimensional (3D) integration technology using Cu interconnections has emerged as a promising solution to improve the performance of silicon microelectronic devices. However, Cu diffuses into SiO2 and requires a barrier layer such as Ta to ensure acceptable reliability. In this paper, the effects of temperature and strain normal to the interface on the inter-diffusion of Cu and Ta at annealing conditions are investigated using a molecular dynamics (MD) technique with embedded atomic method (EAM) potentials. Under thermal annealing conditions without strain, it is found that a Cu-rich diffusion region approximately 2 nm thick is formed at 1000 K after 10 ns of annealing. Ta is capable of diffusing into the interior of Cu but Cu hardly diffuses into the inner lattice of Ta. At the Cu side near the interface an amorphous structure is formed due to the process of diffusion. The diffusion activation energy of Cu and Ta are found to be 0.9769 and 0.586 eV, respectively. However, when a strain is applied, a large number of crystal defects are generated in the sample. As the strain is increased, extrinsic stacking faults (ESFs) and lots of Shockley partial dislocations appear. The density of the dislocations and the diffusion channels increase, promoting the diffusion of Cu atoms into the inner lattice of Ta. The thickness of the diffusion layer increases to 4 times the value when only a temperature load of 700 K is applied. The MD simulations demonstrated that Ta is very effective as a barrier layer under thermal loading only, and its effectiveness is impaired by tensile strain at the Cu/Ta interface. The simulations also clarified the mechanism that caused the impairment. The methodology and approach described in this paper can be followed further to study the effectiveness of barrier layers under various annealing and strain conditions, and to determine the minimum thickness of barrier layers required for a particular application.

Gender Differences in Axial Spondyloarthritis: Women Are Not So Lucky.

PubMed

Rusman, T; van Vollenhoven, R F; van der Horst-Bruinsma, I E

2018-05-12

Ankylosing spondylitis (AS) was historically seen as a predominantly male disease. However, more recent data showed a more homogenous sex prevalence. Unfortunately, in many studies in axial spondyloarthritis (axSpA), the number of women included is low and the analyses are often not stratified for gender distribution. The purpose of this review is to aggregate the existing data on gender differences in axSpA in order to increase the awareness that female axSpA patients are still under-recognized. Several studies considering gender differences revealed that female axSpA patients had different disease manifestations due to different immunological, hormonal, and genetic responses. For instance, allelic frequencies of the AHNK-gene and tissue non-specific alkaline phosphatase (TNAP) haplotypes differed between men and women with ankylosing spondylitis (AS). In addition, different levels of tumor necrosis factor (TNF), interleukins IL-6, IL-17, and IL-18, were found between the two sexes. Furthermore, female patients show a higher diagnostic delay compared to males. Several studies indicate a higher frequency of extra-articular manifestations (EAM) in female axSpA patients, such as enthesitis, psoriasis, and inflammatory bowel disease (IBD), whereas acute anterior uveitis is more prevalent in male patients. Male AS patients more frequently show a higher Bath Ankylosing Spondylitis Radiology Index (BASRI) scores and modified Stoke Ankylosing Spondylitis Spine Scores (mSASSS) than females, which indicates that males have higher radiological damage and radiographic progression. However, disease activity (BASDAI) and quality of life (AsQol) scores are significantly higher in women, and more importantly, they have significantly lower response rates to treatment with TNF inhibitors (TNFi) and a significantly lower drug adherence. Despite the fact that men with axial SpA have a worse radiologic prognosis, women have a high disease burden, in part because they have a longer delay in diagnosis, higher disease activity, and significantly less responsiveness to treatment with TNFi.

Thermal transpiration: A molecular dynamics study

NASA Astrophysics Data System (ADS)

T, Joe Francis; Sathian, Sarith P.

2014-12-01

Thermal transpiration is a phenomenon where fluid molecules move from the cold end towards the hot end of a channel under the influence of longitudinal temperature gradient alone. Although the phenomenon of thermal transpiration is observed at rarefied gas conditions in macro systems, the phenomenon can occur at atmospheric pressure if the characteristic dimensions of the channel is less than 100 nm. The flow through these nanosized channels is characterized by the free molecular flow regimes and continuum theory is inadequate to describe the flow. Thus a non-continuum method like molecular dynamics (MD) is necessary to study such phenomenon. In the present work, MD simulations were carried out to investigate the occurance of thermal transpiration in copper and platinum nanochannels at atmospheric pressure conditions. The mean pressure of argon gas confined inside the nano channels was maintained around 1 bar. The channel height is maintained at 2nm. The argon atoms interact with each other and with the wall atoms through the Lennard-Jones potential. The wall atoms are modelled using an EAM potential. Further, separate simulations were carried out where a Harmonic potential is used for the atom-atom interaction in the platinum channel. A thermally insulating wall was introduced between the low and high temperature regions and those wall atoms interact with fluid atoms through a repulsive potential. A reduced cut off radius were used to achieve this. Thermal creep is induced by applying a temperature gradient along the channel wall. It was found that flow developed in the direction of the increasing temperature gradient of the wall. An increase in the volumetric flux was observed as the length of the cold and the hot regions of the wall were increased. The effect of temperature gradient and the wall-fluid interaction strength on the flow parameters have been studied to understand the phenomenon better.

Patient- and Family-Centered Care as an approach to reducing disparities in asthma outcomes in urban African American children: A review of the literature.

PubMed

Harper, Felicity W K; Eggly, Susan; Crider, Beverly; Kobayashi, Hitomi; Kathleen, R N; Meert, L; Ball, Allison; Penner, Louis A; Gray, Herman; Albrecht, Terrance L

2015-06-01

We thank Cathy Eames (Director, Library Services, Detroit Medical Center) for valuable input and assistance with the search strategy. Funding for this research was supported by a grant from Children's Hospital of Michigan Research Foundation (Principal Investigator: Terrance L. Albrecht, Ph.D.). Patient- and family-centered care (PFCC) has the potential to address disparities in access and quality of healthcare for African American pediatric asthma patients by accommodating and responding to the individual needs of patients and families. To identify and evaluate research on the impact of family-provider interventions that reflect elements of PFCC on reducing disparities in the provision, access, quality, and use of healthcare services for African American pediatric asthma patients. Electronic searches were conducted using PubMed, CINAHL, and Psyclnfo databases. Inclusion criteria were peer-reviewed, English-language articles on family-provider interventions that (a) reflected one or more elements of PFCC and (b) addressed healthcare disparities in urban African American pediatric asthma patients (≤18years). Thirteen interventions or programs were identified and reviewed. Designs included randomized clinical trials, controlled clinical trials, pre- and post-interventions, and program evaluations. Few interventions were identified as explicitly providing PFCC in a pediatric asthma context, possibly because of a lack of consensus on what constitutes PFCC in practice. Some studies have demonstrated that PFCC improves satisfaction and communication during clinical interactions. More empirical research is needed to understand whether PFCC interventions reduce care disparities and improve the provision, access, and quality of asthma healthcare for urban African American children. PubMed, CINAHL, and Psyclnfo AA-African American: CCT-Controlled clinical trial; ED-Emergency Department; ETS-Environmental tobacco smoke; FCC- Family Centered Care; PFCC-Patient and Family Centered Care; RCT- Randomized, controlled trial. © 2015 National Medical Association. Published by Elsevier Inc. All rights reserved.

Spectro-temporal modulation masking patterns reveal frequency selectivity.

PubMed

Oetjen, Arne; Verhey, Jesko L

2015-02-01

The present study investigated the possibility that the human auditory system demonstrates frequency selectivity to spectro-temporal amplitude modulations. Threshold modulation depth for detecting sinusoidal spectro-temporal modulations was measured using a generalized masked threshold pattern paradigm with narrowband masker modulations. Four target spectro-temporal modulations were examined, differing in their temporal and spectral modulation frequencies: a temporal modulation of -8, 8, or 16 Hz combined with a spectral modulation of 1 cycle/octave and a temporal modulation of 4 Hz combined with a spectral modulation of 0.5 cycles/octave. The temporal center frequencies of the masker modulation ranged from 0.25 to 4 times the target temporal modulation. The spectral masker-modulation center-frequencies were 0, 0.5, 1, 1.5, and 2 times the target spectral modulation. For all target modulations, the pattern of average thresholds for the eight normal-hearing listeners was consistent with the hypothesis of a spectro-temporal modulation filter. Such a pattern of modulation-frequency sensitivity was predicted on the basis of psychoacoustical data for purely temporal amplitude modulations and purely spectral amplitude modulations. An analysis of separability indicates that, for the present data set, selectivity in the spectro-temporal modulation domain can be described by a combination of a purely spectral and a purely temporal modulation filter function.

Building 9 ISS mock-ups and trainers

NASA Image and Video Library

1999-08-02

Photographic documentation showing the bldg. 9 ISS module mock-ups and trainers. Views include: various overall views of the configuration of the ISS module trainers on the floor of bldg. 9 (08445-46, 08449-51, 08458-61, 08464-65, 08469, 08471, 08476); various portions of the mock-ups (08447-48, 08470); views of the Node 2, Experiment Module and Logistics Module (08452); Node 2 (08453, 08466); Destiny and Node 2 (08454); Destiny, Unity and Airlock (08455); Zarya, Service Module and shuttle mock-ups (08456); Logistics Module and Experiment Module (08457, 08468); various views of Columbia, Node 2 and Destiny (08462-63); Columbus, Node 2, Experiment Module and Logistics Module (08467); U.S. Laboratory module (08472); Logistics Module (08473); module layout (08474); Logistics Module and Experiment Module (08475).

Modulation limit of semiconductor lasers by some parametric modulation schemes

NASA Astrophysics Data System (ADS)

Iga, K.

1985-07-01

Using the simple rate equations and small signal analysis, the modulation speed limit of semiconductor lasers with modulation schemes such as gain switching, modulation of nonradiative recombination lifetime of minority carriers, and cavity Q modulation, is calculated and compared with the injection modulation scheme of Ikegami and Suematsu (1968). It is found that the maximum modulation frequency for the gain and Q modulation can exceed the resonance-like frequency by a factor equal to the coefficient of the time derivative of the modulation parameter, though the nonradiative lifetime modulation is not shown to be different from the injection modulation. A solution for the carrier lifetime modulation of LED is obtained, and the possibility of wideband modulation in this scheme is demonstrated.

Pipe inspection and repair system

NASA Technical Reports Server (NTRS)

Schempf, Hagen (Inventor); Mutschler, Edward (Inventor); Chemel, Brian (Inventor); Boehmke, Scott (Inventor); Crowley, William (Inventor)

2004-01-01

A multi-module pipe inspection and repair device. The device includes a base module, a camera module, a sensor module, an MFL module, a brush module, a patch set/test module, and a marker module. Each of the modules may be interconnected to construct one of an inspection device, a preparation device, a marking device, and a repair device.

Supported PV module assembly

DOEpatents

Mascolo, Gianluigi; Taggart, David F.; Botkin, Jonathan D.; Edgett, Christopher S.

2013-10-15

A supported PV assembly may include a PV module comprising a PV panel and PV module supports including module supports having a support surface supporting the module, a module registration member engaging the PV module to properly position the PV module on the module support, and a mounting element. In some embodiments the PV module registration members engage only the external surfaces of the PV modules at the corners. In some embodiments the assembly includes a wind deflector with ballast secured to a least one of the PV module supports and the wind deflector. An array of the assemblies can be secured to one another at their corners to prevent horizontal separation of the adjacent corners while permitting the PV modules to flex relative to one another so to permit the array of PV modules to follow a contour of the support surface.

Experiment module concepts study. Volume 3: Module and subsystem design

NASA Technical Reports Server (NTRS)

Hunter, J. R.; Chiarappa, D. J.

1970-01-01

The final common module set exhibiting wide commonality is described. The set consists of three types of modules: one free flying module and two modules that operate attached to the space station. The common module designs provide for the experiment program as defined. The feasibility, economy, and practicality of these modules hinges on factors that do not affect the approach or results of the commonality process, but are important to the validity of the common module concepts. Implementation of the total experiment program requires thirteen common modules: five CM-1, five CM-3, and three CM-4 modules.

Intermediate load modules for test and evaluation

NASA Technical Reports Server (NTRS)

1984-01-01

Photovoltaic modules were tested for qualification. Tests involved the following: (1) delivery of 20 solar cells for use as reference cells; (2) module documentation and inspection plans specifying the 10 Group I modules; (3) design review of module documentation from Group I modules; (4) revise module documentation to overcome any problems of deficiencies associated with the Group I modules; (5) delivery of 10 Group II modules built to revised specifications; (6) testing of Group II modules to the criteria as outlined in qualification specification. It is found that the solarvolt MSP43E40B satisfies the design criteria of qualification specification for intermediate load modules. Design changes were made in the Group I modules to overcome the deficiencies which allowed Group II modules to pass the qualification tests.

Extending the data rate of non-line-of-sight UV communication with polarization modulation

NASA Astrophysics Data System (ADS)

Yin, Hongwei; Jia, Honghui; Zhang, Hailiang; Wang, Xiaofeng; Chang, Shengli; Yang, Juncai

2012-10-01

With low radiation background of solar-blind UV and strong scattering of UV photons by atmospheric particles, UV communication can be made use of to set up a non-line-of-sight (NLOS) free-space optical communication link. Polarization modulation, besides the traditional intensity modulation, is presented to enhance the data rate of the UV communication system. The configuration and the working process of the dually modulated UV communication system with intensity modulation and polarization, the theoretical evaluation of polarization modulation, and a numerical of the scattering matrix are presented, with the conclusion that polarization modulation is achievable. By adding the polarizing devices and changing the coding procedures, the existing singly-modulated UV communication systems with intensity modulation are easily modified to be dually-modulated ones with polarization modulation and intensity modulation. Ideally speaking, the data rate of the dually-modulated UV communication system is the product of the data rate of the singly modulated system and the number of polarization modulation.

Advanced insulated gate bipolar transistor gate drive

DOEpatents

Short, James Evans [Monongahela, PA; West, Shawn Michael [West Mifflin, PA; Fabean, Robert J [Donora, PA

2009-08-04

A gate drive for an insulated gate bipolar transistor (IGBT) includes a control and protection module coupled to a collector terminal of the IGBT, an optical communications module coupled to the control and protection module, a power supply module coupled to the control and protection module and an output power stage module with inputs coupled to the power supply module and the control and protection module, and outputs coupled to a gate terminal and an emitter terminal of the IGBT. The optical communications module is configured to send control signals to the control and protection module. The power supply module is configured to distribute inputted power to the control and protection module. The control and protection module outputs on/off, soft turn-off and/or soft turn-on signals to the output power stage module, which, in turn, supplies a current based on the signal(s) from the control and protection module for charging or discharging an input capacitance of the IGBT.

Photovoltaic module and interlocked stack of photovoltaic modules

DOEpatents

Wares, Brian S.

2014-09-02

One embodiment relates to an arrangement of photovoltaic modules configured for transportation. The arrangement includes a plurality of photovoltaic modules, each photovoltaic module including a frame. A plurality of individual male alignment features and a plurality of individual female alignment features are included on each frame. Adjacent photovoltaic modules are interlocked by multiple individual male alignment features on a first module of the adjacent photovoltaic modules fitting into and being surrounded by corresponding individual female alignment features on a second module of the adjacent photovoltaic modules. Other embodiments, features and aspects are also disclosed.

Frequency response control of semiconductor laser by using hybrid modulation scheme.

PubMed

Mieda, Shigeru; Yokota, Nobuhide; Isshiki, Ryuto; Kobayashi, Wataru; Yasaka, Hiroshi

2016-10-31

A hybrid modulation scheme that simultaneously applies the direct current modulation and intra-cavity loss modulation to a semiconductor laser is proposed. Both numerical calculations using rate equations and experiments using a fabricated laser show that the hybrid modulation scheme can control the frequency response of the laser by changing a modulation ratio and time delay between the two modulations. The modulation ratio and time delay provide the degree of signal mixing of the two modulations and an optimum condition is found when a non-flat frequency response for the intra-cavity loss modulation is compensated by that for the direct current modulation. We experimentally confirm a 8.64-dB improvement of the modulation sensitivity at 20 GHz compared with the pure direct current modulation with a 0.7-dB relaxation oscillation peak.

Auditory sensitivity to spectral modulation phase reversal as a function of modulation depth

PubMed Central

Grose, John

2018-01-01

The present study evaluated auditory sensitivity to spectral modulation by determining the modulation depth required to detect modulation phase reversal. This approach may be preferable to spectral modulation detection with a spectrally flat standard, since listeners appear unable to perform the task based on the detection of temporal modulation. While phase reversal thresholds are often evaluated by holding modulation depth constant and adjusting modulation rate, holding rate constant and adjusting modulation depth supports rate-specific assessment of modulation processing. Stimuli were pink noise samples, filtered into seven octave-wide bands (0.125–8 kHz) and spectrally modulated in dB. Experiment 1 measured performance as a function of modulation depth to determine appropriate units for adaptive threshold estimation. Experiment 2 compared thresholds in dB for modulation detection with a flat standard and modulation phase reversal; results supported the idea that temporal cues were available at high rates for the former but not the latter. Experiment 3 evaluated spectral modulation phase reversal thresholds for modulation that was restricted to either one or two neighboring bands. Flanking bands of unmodulated noise had a larger detrimental effect on one-band than two-band targets. Thresholds for high-rate modulation improved with increasing carrier frequency up to 2 kHz, whereas low-rate modulation appeared more consistent across frequency, particularly in the two-band condition. Experiment 4 measured spectral weights for spectral modulation phase reversal detection and found higher weights for bands in the spectral center of the stimulus than for the lowest (0.125 kHz) or highest (8 kHz) band. Experiment 5 compared performance for highly practiced and relatively naïve listeners, and found weak evidence of a larger practice effect at high than low spectral modulation rates. These results provide preliminary data for a task that may provide a better estimate of sensitivity to spectral modulation than spectral modulation detection with a flat standard. PMID:29621338

A-7E Software Module Guide.

DTIC Science & Technology

1981-12-08

o 14 A& B:2.1 Function Driver Module.. ..... .... 14’ ’: B:2.2 Shared Services Module . . . o o . 0 -15 M’ 5:3 Software Decision Module...2.1.13 Weapon Release Functions... ........24 C:2.l.14 Ground Test Functions .. ........... 24 C:2.2 Shared Services Module Decomposition. ........24 C...Driver (FD) Module supported by a Shared Services (SS) Module. B:2.1 FUNCTION DRIVER MODULE The Function Driver Module consists of a set of individual

47 CFR 73.14 - AM broadcast definitions.

Code of Federal Regulations, 2012 CFR

2012-10-01

... in which the carrier wave is modulated in accordance with the system of amplitude modulation and the characteristics of the modulating wave. Amplitude modulator stage. The last amplifier stage of the modulating wave... amplitude of the carrier wave in an amplitude-modulated transmitter when modulation is applied under...

47 CFR 73.14 - AM broadcast definitions.

Code of Federal Regulations, 2013 CFR

2013-10-01

... in which the carrier wave is modulated in accordance with the system of amplitude modulation and the characteristics of the modulating wave. Amplitude modulator stage. The last amplifier stage of the modulating wave... amplitude of the carrier wave in an amplitude-modulated transmitter when modulation is applied under...

47 CFR 73.14 - AM broadcast definitions.

Code of Federal Regulations, 2014 CFR

2014-10-01

... in which the carrier wave is modulated in accordance with the system of amplitude modulation and the characteristics of the modulating wave. Amplitude modulator stage. The last amplifier stage of the modulating wave... amplitude of the carrier wave in an amplitude-modulated transmitter when modulation is applied under...

Microarray and network-based identification of functional modules and pathways of active tuberculosis.

PubMed

Bian, Zhong-Rui; Yin, Juan; Sun, Wen; Lin, Dian-Jie

2017-04-01

Diagnose of active tuberculosis (TB) is challenging and treatment response is also difficult to efficiently monitor. The aim of this study was to use an integrated analysis of microarray and network-based method to the samples from publically available datasets to obtain a diagnostic module set and pathways in active TB. Towards this goal, background protein-protein interactions (PPI) network was generated based on global PPI information and gene expression data, following by identification of differential expression network (DEN) from the background PPI network. Then, ego genes were extracted according to the degree features in DEN. Next, module collection was conducted by ego gene expansion based on EgoNet algorithm. After that, differential expression of modules between active TB and controls was evaluated using random permutation test. Finally, biological significance of differential modules was detected by pathways enrichment analysis based on Reactome database, and Fisher's exact test was implemented to extract differential pathways for active TB. Totally, 47 ego genes and 47 candidate modules were identified from the DEN. By setting the cutoff-criteria of gene size >5 and classification accuracy ≥0.9, 7 ego modules (Module 4, Module 7, Module 9, Module 19, Module 25, Module 38 and Module 43) were extracted, and all of them had the statistical significance between active TB and controls. Then, Fisher's exact test was conducted to capture differential pathways for active TB. Interestingly, genes in Module 4, Module 25, Module 38, and Module 43 were enriched in the same pathway, formation of a pool of free 40S subunits. Significant pathway for Module 7 and Module 9 was eukaryotic translation termination, and for Module 19 was nonsense mediated decay enhanced by the exon junction complex (EJC). Accordingly, differential modules and pathways might be potential biomarkers for treating active TB, and provide valuable clues for better understanding of molecular mechanism of active TB. Copyright © 2017 Elsevier Ltd. All rights reserved.

MEG evidence that the central auditory system simultaneously encodes multiple temporal cues.

PubMed

Simpson, Michael I G; Barnes, Gareth R; Johnson, Sam R; Hillebrand, Arjan; Singh, Krish D; Green, Gary G R

2009-09-01

Speech contains complex amplitude modulations that have envelopes with multiple temporal cues. The processing of these complex envelopes is not well explained by the classical models of amplitude modulation processing. This may be because the evidence for the models typically comes from the use of simple sinusoidal amplitude modulations. In this study we used magnetoencephalography (MEG) to generate source space current estimates of the steady-state responses to simple one-component amplitude modulations and to a two-component amplitude modulation. A two-component modulation introduces the simplest form of modulation complexity into the waveform; the summation of the two-modulation rates introduces a beat-like modulation at the difference frequency between the two modulation rates. We compared the cortical representations of responses to the one-component and two-component modulations. In particular, we show that the temporal complexity in the two-component amplitude modulation stimuli was preserved at the cortical level. The method of stimulus normalization that we used also allows us to interpret these results as evidence that the important feature in sound modulations is the relative depth of one modulation rate with respect to another, rather than the absolute carrier-to-sideband modulation depth. More generally, this may be interpreted as evidence that modulation detection accurately preserves a representation of the modulation envelope. This is an important observation with respect to models of modulation processing, as it suggests that models may need a dynamic processing step to effectively model non-stationary stimuli. We suggest that the classic modulation filterbank model needs to be modified to take these findings into account.

Design of EPON far-end equipment based on FTTH

NASA Astrophysics Data System (ADS)

Feng, Xiancheng; Yun, Xiang

2008-12-01

Now, most favors fiber access is mainly the EPON fiber access system. Inheriting from the low cost of Ethernet, usability and bandwidth of optical network, EPON technology is one of the best technologies in fiber access and is adopted by the carriers all over the world widely. According to the scheme analysis to FTTH fan-end equipment, hardware design of ONU is proposed in this paper. The FTTH far-end equipment software design deference modulation design concept, it divides the software designment into 5 function modules: the module of low-layer driver, the module of system management, the module of master/slave communication, and the module of main/Standby switch and the module of command line. The software flow of the host computer is also analyzed. Finally, test is made for Ethernet service performance of FTTH far-end equipment, E1 service performance and the optical path protection switching, and so on. The results of test indicates that all the items are accordance with technical request of far-end ONU equipment and possess good quality and fully reach the requirement of telecommunication level equipment. The far-end equipment of FTTH divides into several parts based on the function: the control module, the exchange module, the UNI interface module, the ONU module, the EPON interface module, the network management debugging module, the voice processing module, the circuit simulation module, the CATV module. In the downstream direction, under the protect condition, we design 2 optical modules. The system can set one group optical module working and another group optical module closure when it is initialized. When the optical fiber line is cut off, the LOS warning comes out. It will cause MUX to replace another group optical module, simultaneously will reset module 3701/3711 and will make it again test the distance, and will give the plug board MPC850 report through the GPIO port. During normal mode, the downstream optical signal is transformed into the electrical signal by the optical module. In the upstream direction, the upstream Ethernet data is retransmitted through the exchange chip BCM5380 to the GMII/MII in module 3701/3711, and then is transmitted to EPON port. The 2MB data are transformed the Ethernet data packet in the plug board TDM, then it's transmitted to the interface MII of the module 3701/3711. The software design of FTTH far-end equipment compiles with modulation design concept. According to the system realization duty, the software is divided into 5 function modules: low-level driver module, system management module, master/slave communication module, the man/Standby switch module and the command line module. The FTTH far-end equipment test, is mainly the Ethernet service performance test, E1 service performance test and the optical path protection switching test and so on the key specification test.

Model Development of Degradation of PV Modules Backsheet with Locating Place of Module

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kempe, Michael D; Wang, Yu; Fairbrother, Andrew

Performance of a photovoltaic (PV) module is related to the micro-environment around the module. The position of photovoltaic modules in an array row have a large effect on the yellowing and gloss of PV module backsheet exposed in Dfa climatic zone (Gaithersburg, MD) with a polyethylene naphthalate (PEN) outer layer. Stress/Response models of yellowing and gloss-losing as function of location parameters of module, including the shed, row, measurement position in a same module and the distance of module location to the row center, are under development. The module installation height had the greatest influence on degradation of PEN PV backsheetmore » in the Dfa climatic zone. The module backsheets at the end of an array have higher degradation rate (edge effect). The edge effect decreases with increasing of module installation heights.« less

Systems and methods for reducing transient voltage spikes in matrix converters

DOEpatents

Kajouke, Lateef A.; Perisic, Milun; Ransom, Ray M.

2013-06-11

Systems and methods are provided for delivering energy using an energy conversion module that includes one or more switching elements. An exemplary electrical system comprises a DC interface, an AC interface, an isolation module, a first conversion module between the DC interface and the isolation module, and a second conversion module between the AC interface and the isolation module. A control module is configured to operate the first conversion module to provide an injection current to the second conversion module to reduce a magnitude of a current through a switching element of the second conversion module before opening the switching element.

Design and long-term monitoring of DSC/CIGS tandem solar module

NASA Astrophysics Data System (ADS)

Vildanova, M. F.; Nikolskaia, A. B.; Kozlov, S. S.; Shevaleevskiy, O. I.

2015-11-01

This paper describes the design and development of tandem dye-sensitized/Cu(In, Ga)Se (DSC/CIGS) PV modules. The tandem PV module comprised of the top DSC module and a bottom commercial 0,8 m2 CIGS module. The top DSC module was made of 10 DSC mini-modules with the field size of 20 × 20 cm2 each. Tandem DSC/CIGS PV modules were used for providing the long-term monitoring of energy yield and electrical parameters in comparison with standalone CIGS modules under outdoor conditions. The outdoor test facility, containing solar modules of both types and a measurement unit, was located on the roof of the Institute of Biochemical Physics in Moscow. The data obtained during monitoring within the 2014 year period has shown the advantages of the designed tandem DSC/CIGS PV-modules over the conventional CIGS modules, especially for cloudy weather and low-intensity irradiation conditions.

Apparatus and method for interaction phenomena with world modules in data-flow-based simulation

DOEpatents

Xavier, Patrick G [Albuquerque, NM; Gottlieb, Eric J [Corrales, NM; McDonald, Michael J [Albuquerque, NM; Oppel, III, Fred J.

2006-08-01

A method and apparatus accommodate interaction phenomenon in a data-flow-based simulation of a system of elements, by establishing meta-modules to simulate system elements and by establishing world modules associated with interaction phenomena. World modules are associated with proxy modules from a group of meta-modules associated with one of the interaction phenomenon. The world modules include a communication world, a sensor world, a mobility world, and a contact world. World modules can be further associated with other world modules if necessary. Interaction phenomenon are simulated in corresponding world modules by accessing member functions in the associated group of proxy modules. Proxy modules can be dynamically allocated at a desired point in the simulation to accommodate the addition of elements in the system of elements such as a system of robots, a system of communication terminals, or a system of vehicles, being simulated.

Longitudinal On-Column Thermal Modulation for Comprehensive Two-Dimensional Liquid Chromatography.

PubMed

Creese, Mari E; Creese, Mathew J; Foley, Joe P; Cortes, Hernan J; Hilder, Emily F; Shellie, Robert A; Breadmore, Michael C

2017-01-17

Longitudinal on-column thermal modulation for comprehensive two-dimensional liquid chromatography is introduced. Modulation optimization involved a systematic investigation of heat transfer, analyte retention, and migration velocity at a range of temperatures. Longitudinal on-column thermal modulation was realized using a set of alkylphenones and compared to a conventional valve-modulator employing sample loops. The thermal modulator showed a reduced modulation-induced pressure impact than valve modulation, resulting in reduced baseline perturbation by a factor of 6; yielding a 6-14-fold improvement in signal-to-noise. A red wine sample was analyzed to demonstrate the potential of the longitudinal on-column thermal modulator for separation of a complex sample. Discrete peaks in the second dimension using the thermal modulator were 30-55% narrower than with the valve modulator. The results shown herein demonstrate the benefits of an active focusing modulator, such as reduced detection limits and increased total peak capacity.

High-frequency modulation of the four states of polarization of light with a single phase modulator

NASA Astrophysics Data System (ADS)

Compain, Eric; Drevillon, Bernard

1998-04-01

A method for light polarization modulation is described. It allows us to independently modulate, at a high frequency, the four components of the Stokes vector of light using a single phase modulator. It works in a double-pass configuration: the polarization of light is modulated a first time by the phase modulator, and is then modified by a coupling object before being modulated a second time by the same modulator. The coupling object consists of multiple glass plates, oriented at the Brewster angle, acting as a partial polarizer and in a right angle prism acting as a phase shifter and back reflector. Its polarimetric properties are obtained from refractive index contrast effects, which provides optimized and constant properties over a wide spectral range. The phase modulator can be either an electro-optic modulator providing a very high-frequency capability (up to 100 MHz) or a photoelastic modulator providing a wide spectral range capability. It is robust because there is no moving part and simple to implement because of the presence of one modulation. It displays a high level of sensitivity because all the components are high-frequency modulated. Two applications using this modulator in a polarimeter or in a polarization states generator are described. The four modulations, having the same fundamental frequency, are easily demodulated by numerical data processing. Optimized demodulation processing, adapted to the different kind of phase modulator is described. Its adaptation taking into account the bandwidth limitation and the variation of the sampling phase, are finally presented in the case of a photoelastic modulator.

Systems and methods for deactivating a matrix converter

DOEpatents

Ransom, Ray M.

2013-04-02

Systems and methods are provided for deactivating a matrix conversion module. An electrical system comprises an alternating current (AC) interface, a matrix conversion module coupled to the AC interface, an inductive element coupled between the AC interface and the matrix conversion module, and a control module. The control module is coupled to the matrix conversion module, and in response to a shutdown condition, the control module is configured to operate the matrix conversion module to deactivate the first conversion module when a magnitude of a current through the inductive element is less than a threshold value.

The development of form two mathematics i-Think module (Mi-T2)

NASA Astrophysics Data System (ADS)

Yao, Foo Jing; Abdullah, Mohd Faizal Nizam Lee; Tien, Lee Tien

2017-05-01

This study aims to develop a training module i-THINK Mathematics Form Two (Mi-T2) to increase the higher-order thinking skills of students. The Mi-T2 training module was built based on the Sidek Module Development Model (2001). Constructivist learning theory, cognitive learning theory, i-THINK map and higher order thinking skills were the building blocks of the module development. In this study, researcher determined the validity and reliability of Mi-T2 module. The design being used in this study was descriptive study. To determine the needs of Mi-T2 module, questionnaires and literature review were used to collect data. When the need of the module was determined, the module was built and a pilot study was conducted to test the reliability of the Mi-T2 module. The pilot study was conducted at a secondary school in North Kinta, Perak. A Form Two class was selected to be the sample study through clustered random sampling. The pilot study was conducted for two months and one topic had been studied. The Mi-T2 module was evaluated by five expert panels to determine the content validity of the module. The instruments being used in the study were questionnaires about the necessity of the Mi-T2 module for guidance, questionnaires about the validity of the module and questionnaires concerning the reliability of the module. Statistical analysis was conducted to determine the validity and reliability coefficients of the Mi-T2 module. The content validity of Mi-T2 module was determined by Cohen's Kappa's (1968) agreement coefficient and the reliability of Mi-T2 module was determined by Cronbach Alpha's value scale. The content validity of Mi-T2 module was 0.89 and the Cronbach Alpha's value of Mi-T2 module was 0.911.

Characteristics of spectro-temporal modulation frequency selectivity in humans.

PubMed

Oetjen, Arne; Verhey, Jesko L

2017-03-01

There is increasing evidence that the auditory system shows frequency selectivity for spectro-temporal modulations. A recent study of the authors has shown spectro-temporal modulation masking patterns that were in agreement with the hypothesis of spectro-temporal modulation filters in the human auditory system [Oetjen and Verhey (2015). J. Acoust. Soc. Am. 137(2), 714-723]. In the present study, that experimental data and additional data were used to model this spectro-temporal frequency selectivity. The additional data were collected to investigate to what extent the spectro-temporal modulation-frequency selectivity results from a combination of a purely temporal amplitude-modulation filter and a purely spectral amplitude-modulation filter. In contrast to the previous study, thresholds were measured for masker and target modulations with opposite directions, i.e., an upward pointing target modulation and a downward pointing masker modulation. The comparison of this data set with previous corresponding data with the same direction from target and masker modulations indicate that a specific spectro-temporal modulation filter is required to simulate all aspects of spectro-temporal modulation frequency selectivity. A model using a modified Gabor filter with a purely temporal and a purely spectral filter predicts the spectro-temporal modulation masking data.

Inflight - Apollo 9 (Crew Activities)

NASA Image and Video Library

1969-03-06

S69-26150 (6 March 1969) --- Television watchers on Earth saw this view of the Apollo 9 Command Module during the second live telecast from Apollo 9 early Thursday afternoon on the fourth day in space. This view is looking through the docking window of the Lunar Module. The cloud-covered Earth can be seen in the background. Inside the Lunar Module "Spider" were Astronauts James A. McDivitt, Apollo 9 commander; and Russell L. Schweickart, lunar module pilot. At this moment Apollo 9 was orbiting Earth with the Command and Service Modules docked nose-to-nose with the Lunar Module. Astronaut David R. Scott, command module pilot, remained at the controls in the Command Module "Gumdrop" while the other two astronauts checked out the Lunar Module. McDivitt and Schweickart moved into the Lunar Module from the Command Module by way of the docking tunnel.

Electro-Optic Modulator and Method

DTIC Science & Technology

An optical intensity modulator which uses a Sagnac interferometer having an electro - optic phase modulator therein. An electric modulation signal is...modulating the optical signals by the electrical signal, the electro - optic effect in the modulator phase shifts the optical signals with respect to one another

Fuel premixing module for gas turbine engine combustor

NASA Technical Reports Server (NTRS)

Chin, Jushan (Inventor); Rizk, Nader K. (Inventor); Razdan, Mohan K. (Inventor); Marshall, Andre W. (Inventor)

2005-01-01

A fuel-air premixing module is designed to reduce emissions from a gas turbine engine. In one form, the premixing module includes a central pilot premixer module with a main premixer module positioned thereround. Each of the portions of the fuel-air premixing module include an axial inflow swirler with a plurality of fixed swirler vanes. Fuel is injected into the main premixer module between the swirler vanes of the axial inflow swirler and at an acute angle relative to the centerline of the premixing module.

Distributed performance counters

DOEpatents

Davis, Kristan D; Evans, Kahn C; Gara, Alan; Satterfield, David L

2013-11-26

A plurality of first performance counter modules is coupled to a plurality of processing cores. The plurality of first performance counter modules is operable to collect performance data associated with the plurality of processing cores respectively. A plurality of second performance counter modules are coupled to a plurality of L2 cache units, and the plurality of second performance counter modules are operable to collect performance data associated with the plurality of L2 cache units respectively. A central performance counter module may be operable to coordinate counter data from the plurality of first performance counter modules and the plurality of second performance modules, the a central performance counter module, the plurality of first performance counter modules, and the plurality of second performance counter modules connected by a daisy chain connection.

The design of automatic software testing module for civil aviation information system

NASA Astrophysics Data System (ADS)

Qi, Qi; Sun, Yang

2018-05-01

In this paper, the practical innovation design is carried out according to the urgent needs of the automatic testing module of civil aviation information system. Firstly, the background and significance of the automatic testing module of civil aviation information system is expounded, and the current research status of automatic testing module and the advantages and disadvantages of related software are analyzed. Then, from the three aspects of macro demand, module functional requirement and module nonfunctional demand, we further study the needs of automatic testing module of civil aviation information system. Finally, from the four aspects of module structure, module core function, database and security, we have made an innovative plan for the automatic testing module of civil aviation information system.

A note on elongations of summable QTAG-modules.

PubMed

Mehdi, Alveera; Sikander, Fahad; Naji, Sabah A R K

2013-01-01

A right module M over an associative ring with unity is a QTAG-module if every finitely generated submodule of any homomorphic image of M is a direct sum of uniserial modules. In this paper we find a suitable condition under which a special ω-elongation of a summable QTAG-module by a ( ω +k)-projective QTAG-module is also a summable QTAG-module.

A Note on Elongations of Summable QTAG-Modules

PubMed Central

Mehdi, Alveera; Naji, Sabah A. R. K.

2013-01-01

A right module M over an associative ring with unity is a QTAG-module if every finitely generated submodule of any homomorphic image of M is a direct sum of uniserial modules. In this paper we find a suitable condition under which a special ω-elongation of a summable QTAG-module by a (ω+k)-projective QTAG-module is also a summable QTAG-module. PMID:24459429

Traumatic Brain Injury: A Guide for Caregivers of Service Members and Veterans

DTIC Science & Technology

2010-01-01

Fracture - Module 1, pages 2, 15, 22, 26...pages 6, 9, 13-16, 20, 22, 25, 27 Skull Fracture - Companion, page 9; Module 1, pages 14-15, 22, 26 Simple Fracture - Module 1, page 15 Compound... Fracture - Module 1, page 15 Depressed Skull Fracture - Module 1, page 15 Basal Skull Fracture - Module 1, page 15 Sleep Changes - Module 2, pages

The Background, Philosophy and Purposes of Team Teaching. Module I.

ERIC Educational Resources Information Center

York, L. Jean

This is the first of seven modules designed to help teachers gain the knowledge and skills needed for successful team teaching. The user may choose one, several or all of the modules, in any sequence, with module 1 recommended as a prerequisite to all the others, and module 5 as a prerequisite to module 6. The pattern of each module is: 1) study…

System for adjusting frequency of electrical output pulses derived from an oscillator

DOEpatents

Bartholomew, David B.

2006-11-14

A system for setting and adjusting a frequency of electrical output pulses derived from an oscillator in a network is disclosed. The system comprises an accumulator module configured to receive pulses from an oscillator and to output an accumulated value. An adjustor module is configured to store an adjustor value used to correct local oscillator drift. A digital adder adds values from the accumulator module to values stored in the adjustor module and outputs their sums to the accumulator module, where they are stored. The digital adder also outputs an electrical pulse to a logic module. The logic module is in electrical communication with the adjustor module and the network. The logic module may change the value stored in the adjustor module to compensate for local oscillator drift or change the frequency of output pulses. The logic module may also keep time and calculate drift.

Unstart coupling mechanism analysis of multiple-modules hypersonic inlet.

PubMed

Hu, Jichao; Chang, Juntao; Wang, Lei; Cao, Shibin; Bao, Wen

2013-01-01

The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

Apparatus for encapsulating a photovoltaic module

DOEpatents

Albright, Scot P.; Dugan, Larry M.

1995-10-24

The subject inventions concern various photovoltaic module designs to protect the module from horizontal and vertical impacts and degradation of solar cell efficiency caused by moisture. In one design, a plurality of panel supports that are positioned adjacent to the upper panel in a photovoltaic module absorb vertical forces exerted along an axis perpendicular to the upper panel. Other designs employ layers of glass and tempered glass, respectively, to protect the module from vertical impacts. A plurality of button-shaped channels is used around the edges of the photovoltaic module to absorb forces applied to the module along an axis parallel to the module and direct moisture away from the module that could otherwise penetrate the module and adversely affect the cells within the module. A spacer is employed between the upper and lower panels that has a coefficient of thermal expansion substantially equivalent to the coefficient of thermal expansion of at least one of the panels.

A deterministic guide for material and mode dependence of on-chip electro-optic modulator performance

NASA Astrophysics Data System (ADS)

Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

2017-10-01

Electro-optic modulation is a key function in optical data communication and possible future optical computing engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While high-performing modulators were demonstrated before, the approaches were taken as ad-hoc. Here we show the first systematic investigation to incorporate a holistic analysis for high-performance and ultra-compact electro-optic modulators on-chip. We show that intricate interplay between active modulation material and optical mode plays a key role in the device operation. Based on physical tradeoffs such as index modulation, loss, optical confinement factors and slow-light effects, we find that bias-material-mode regions exist where high phase modulation and high loss (absorption) modulation is found. This work paves the way for a holistic design rule of electro-optic modulators for on-chip integration.

Integrated unaligned resonant modulator tuning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zortman, William A.; Lentine, Anthony L.

Methods and systems for tuning a resonant modulator are disclosed. One method includes receiving a carrier signal modulated by the resonant modulator with a stream of data having an approximately equal number of high and low bits, determining an average power of the modulated carrier signal, comparing the average power to a predetermined threshold, and operating a tuning device coupled to the resonant modulator based on the comparison of the average power and the predetermined threshold. One system includes an input structure, a plurality of processing elements, and a digital control element. The input structure is configured to receive, frommore » the resonant modulator, a modulated carrier signal. The plurality of processing elements are configured to determine an average power of the modulated carrier signal. The digital control element is configured to operate a tuning device coupled to the resonant modulator based on the average power of the modulated carrier signal.« less

Practical, redundant, failure-tolerant, self-reconfiguring embedded system architecture

DOEpatents

Klarer, Paul R.; Hayward, David R.; Amai, Wendy A.

2006-10-03

This invention relates to system architectures, specifically failure-tolerant and self-reconfiguring embedded system architectures. The invention provides both a method and architecture for redundancy. There can be redundancy in both software and hardware for multiple levels of redundancy. The invention provides a self-reconfiguring architecture for activating redundant modules whenever other modules fail. The architecture comprises: a communication backbone connected to two or more processors and software modules running on each of the processors. Each software module runs on one processor and resides on one or more of the other processors to be available as a backup module in the event of failure. Each module and backup module reports its status over the communication backbone. If a primary module does not report, its backup module takes over its function. If the primary module becomes available again, the backup module returns to its backup status.

Process evaluation distributed system

NASA Technical Reports Server (NTRS)

Moffatt, Christopher L. (Inventor)

2006-01-01

The distributed system includes a database server, an administration module, a process evaluation module, and a data display module. The administration module is in communication with the database server for providing observation criteria information to the database server. The process evaluation module is in communication with the database server for obtaining the observation criteria information from the database server and collecting process data based on the observation criteria information. The process evaluation module utilizes a personal digital assistant (PDA). A data display module in communication with the database server, including a website for viewing collected process data in a desired metrics form, the data display module also for providing desired editing and modification of the collected process data. The connectivity established by the database server to the administration module, the process evaluation module, and the data display module, minimizes the requirement for manual input of the collected process data.

47 CFR 78.115 - Modulation limits.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 47 Telecommunication 4 2010-10-01 2010-10-01 false Modulation limits. 78.115 Section 78.115... SERVICE Technical Regulations § 78.115 Modulation limits. (a) If amplitude modulation is employed, negative modulation peaks shall not exceed 100 percent modulation. [37 FR 3292, Feb. 12, 1972, as amended...

Robot Serviced Space Facility

NASA Technical Reports Server (NTRS)

Purves, Lloyd R. (Inventor)

1992-01-01

A robot serviced space facility includes multiple modules which are identical in physical structure, but selectively differing in function. and purpose. Each module includes multiple like attachment points which are identically placed on each module so as to permit interconnection with immediately adjacent modules. Connection is made through like outwardly extending flange assemblies having identical male and female configurations for interconnecting to and locking to a complementary side of another flange. Multiple rows of interconnected modules permit force, fluid, data and power transfer to be accomplished by redundant circuit paths. Redundant modules of critical subsystems are included. Redundancy of modules and of interconnections results in a space complex with any module being removable upon demand, either for module replacement or facility reconfiguration. without eliminating any vital functions of the complex. Module replacement and facility assembly or reconfiguration are accomplished by a computer controlled articulated walker type robotic manipulator arm assembly having two identical end-effectors in the form of male configurations which are identical to those on module flanges and which interconnect to female configurations on other flanges. The robotic arm assembly moves along a connected set or modules by successively disconnecting, moving and reconnecting alternate ends of itself to a succession of flanges in a walking type maneuver. To transport a module, the robot keeps the transported module attached to one of its end-effectors and uses another flange male configuration of the attached module as a substitute end-effector during walking.

Apollo 9 Command/Service Modules photographed from Lunar Module

NASA Technical Reports Server (NTRS)

1969-01-01

The Apollo 9 Command/Service Modules photographed from the Lunar Module, 'Spider', on the fifth day of the Apollo 9 earth-orbital mission. Docking mechanism is visible in nose of the Command Module, 'Gumdrop'. Object jutting out from the Service Module aft bulkhead is the high-gain S-Band antenna.

78 FR 42758 - 36(b)(1) Arms Sales Notification

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-17

... aircraft, to include: Inlet/Fan Modules, Core Engine Modules, Rear Compressor Drive Turbines, Fan Drive...-PW-229 engines for the Hellenic Air Force F-16 aircraft, to include: Inlet/Fan Modules, Core Engine Modules, Rear Compressor Drive Turbines, Fan Drive Turbine Modules, Augmentor Duct and Nozzle Modules, and...

Cross-Modulation Interference with Lateralization of Mixed-Modulated Waveforms

ERIC Educational Resources Information Center

Hsieh, I-Hui; Petrosyan, Agavni; Goncalves, Oscar F.; Hickok, Gregory; Saberi, Kourosh

2010-01-01

Purpose: This study investigated the ability to use spatial information in mixed-modulated (MM) sounds containing concurrent frequency-modulated (FM) and amplitude-modulated (AM) sounds by exploring patterns of interference when different modulation types originated from different loci as may occur in a multisource acoustic field. Method:…

Lunar Module 4 moved for mating with Lunar Module Adapter at KSC

NASA Technical Reports Server (NTRS)

1969-01-01

Lunar Module 4 in the Kennedy Space Center's Manned Spacecraft Operations Bldg being moved into position for mating with Spacecraft Lunar Module Adapter (SLA) 13 (17809);Lunar Module 4 being moved for mating with the Spacecraft Lunar Module Adapter in the Kennedy Space Center's (KSC) Manned Spacecraft Operations Building. Lunar module 4 will be flown on the Apollo 10 (Spacecraft 106/Saturn 505) lunar orbit mission (17810).

Equity and Urban Service Distribution, Package XVIII. Module 1; Module 2: Handbook for Analyzing the Distribution of Solid Waste Collection Services; Module 3: Handbook for Analyzing the Distribution of Library Services; Module 4: Handbook for Analyzing the Distribution of Park Services; Module 5: Handbook for Analyzing the Distribution of Police Services.

ERIC Educational Resources Information Center

Lucy, William H.; Mladenka, Kenneth R.

This package contains the student materials for five modules which comprise a portion of the National Training and Development Service Urban Management Curriculum Development Project. These modules focus on the distribution of services in urban areas. Module One presents chapters on service distribution and equity, effectiveness, decision making,…

Inflatable nested toroid structure

NASA Technical Reports Server (NTRS)

Johnson, Christopher J. (Inventor); Raboin, Jasen L. (Inventor); Spexarth, Gary R. (Inventor)

2011-01-01

An inflatable structure comprises at least two generally toroidal, inflatable modules. When in a deployed mode, the first, inner module has a major diameter less than that of a second, outer module and is positioned within the inner circumference of the outer module such that the first module is nested circumferentially alongside the second module. The inflatable structure, in a non-deployed, non-inflated mode, is of compact configuration and adapted to be transported to a site of deployment. When deployed, the inflatable structure is of substantially increased interior volume. In one embodiment, access between the interior of the first module and the second module is provided by at least one port or structural pass-through. In another embodiment, the inflatable structure includes at least one additional generally toroidal module external of and circumferentially surrounding the second module.

Modulation Index Adjustment for Recovery of Pure Wavelength Modulation Spectroscopy Second Harmonic Signal Waveforms.

PubMed

Wei, Wei; Chang, Jun; Wang, Qiang; Qin, Zengguang

2017-01-15

A new technique of modulation index adjustment for pure wavelength modulation spectroscopy second harmonic signal waveforms recovery is presented. As the modulation index is a key parameter in determining the exact form of the signals generated by the technique of wavelength modulation spectroscopy, the method of modulation index adjustment is applied to recover the second harmonic signal with wavelength modulation spectroscopy. By comparing the measured profile with the theoretical profile by calculation, the relationship between the modulation index and average quantities of the scanning wavelength can be obtained. Furthermore, when the relationship is applied in the experimental setup by point-by-point modulation index modification for gas detection, the results show good agreement with the theoretical profile and signal waveform distortion (such as the amplitude modulation effect caused by diode laser) can be suppressed. Besides, the method of modulation index adjustment can be used in many other aspects which involve profile improvement. In practical applications, when the amplitude modulation effect can be neglected and the stability of the detection system is limited by the sampling rate of analog-to-digital, modulation index adjustment can be used to improve detection into softer inflection points and solve the insufficient sampling problem. As a result, measurement stability is improved by 40%.

Modulation Index Adjustment for Recovery of Pure Wavelength Modulation Spectroscopy Second Harmonic Signal Waveforms

PubMed Central

Wei, Wei; Chang, Jun; Wang, Qiang; Qin, Zengguang

2017-01-01

A new technique of modulation index adjustment for pure wavelength modulation spectroscopy second harmonic signal waveforms recovery is presented. As the modulation index is a key parameter in determining the exact form of the signals generated by the technique of wavelength modulation spectroscopy, the method of modulation index adjustment is applied to recover the second harmonic signal with wavelength modulation spectroscopy. By comparing the measured profile with the theoretical profile by calculation, the relationship between the modulation index and average quantities of the scanning wavelength can be obtained. Furthermore, when the relationship is applied in the experimental setup by point-by-point modulation index modification for gas detection, the results show good agreement with the theoretical profile and signal waveform distortion (such as the amplitude modulation effect caused by diode laser) can be suppressed. Besides, the method of modulation index adjustment can be used in many other aspects which involve profile improvement. In practical applications, when the amplitude modulation effect can be neglected and the stability of the detection system is limited by the sampling rate of analog-to-digital, modulation index adjustment can be used to improve detection into softer inflection points and solve the insufficient sampling problem. As a result, measurement stability is improved by 40%. PMID:28098842

Revealing the Hidden Relationship by Sparse Modules in Complex Networks with a Large-Scale Analysis

PubMed Central

Jiao, Qing-Ju; Huang, Yan; Liu, Wei; Wang, Xiao-Fan; Chen, Xiao-Shuang; Shen, Hong-Bin

2013-01-01

One of the remarkable features of networks is module that can provide useful insights into not only network organizations but also functional behaviors between their components. Comprehensive efforts have been devoted to investigating cohesive modules in the past decade. However, it is still not clear whether there are important structural characteristics of the nodes that do not belong to any cohesive module. In order to answer this question, we performed a large-scale analysis on 25 complex networks with different types and scales using our recently developed BTS (bintree seeking) algorithm, which is able to detect both cohesive and sparse modules in the network. Our results reveal that the sparse modules composed by the cohesively isolated nodes widely co-exist with the cohesive modules. Detailed analysis shows that both types of modules provide better characterization for the division of a network into functional units than merely cohesive modules, because the sparse modules possibly re-organize the nodes in the so-called cohesive modules, which lack obvious modular significance, into meaningful groups. Compared with cohesive modules, the sizes of sparse ones are generally smaller. Sparse modules are also found to have preferences in social and biological networks than others. PMID:23762457

Design of smart home terminal controller based on ZigBee

NASA Astrophysics Data System (ADS)

Li, Biqing; Li, Zhao; Zhang, Hongyan

2018-04-01

With the development in scienc and technology, and the improvement of living conditions, people pay more and more attention to the comfort of household life. Therefore, smart home has become the development trend of the future furniture. This design is composed of three blocks: transmitting module, receiving module and data acquisition module. ZigBee and STC89C52 belong to launch module as well as belong to receive module. Launch module contains ZigBee, serial communication module and monolithic STC89C52. The receiving module contains light control parts, curtain control part, ZigBee and microcontroller STC89C52. Data acquisition module includes temperature and humidity detection.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott, Jeffrey Wayne; Pratt, Richard M

A modulated backscatter radio frequency identification device includes a diode detector configured to selectively modulate a reply signal onto an incoming continuous wave; communications circuitry configured to provide a modulation control signal to the diode detector, the diode detector being configured to modulate the reply signal in response to be modulation control signal; and circuitry configured to increase impedance change at the diode detector which would otherwise not occur because the diode detector rectifies the incoming continuous wave while modulating the reply signal, whereby reducing the rectified signal increases modulation depth by removing the reverse bias effects on impedance changes.more » Methods of improving depth of modulation in a modulated backscatter radio frequency identification device are also provided.« less

Clock and reset synchronization of high-integrity lockstep self-checking pairs

NASA Technical Reports Server (NTRS)

Brickner, Christopher (Inventor); Oliver, Brett D. (Inventor); Caltagirone, Joseph (Inventor)

2012-01-01

An apparatus comprises first and second modules configured to operate in a lockstep mode and a reset mode. Each of the first and second modules is configured to asynchronously enter the reset mode when a parent reset signal is asserted at the respective each module. Each of the first and second modules is configured to, in response to the asserted parent reset signal being negated at the respective each module, indicate to the respective other module that the respective each module is ready to exit the reset mode and exit the reset mode when the respective other module has also indicated that the respective other module is ready to exit the reset mode.

Wide-band analog frequency modulation of optic signals using indirect techniques

NASA Technical Reports Server (NTRS)

Fitzmartin, D. J.; Balboni, E. J.; Gels, R. G.

1991-01-01

The wideband frequency modulation (FM) of an optical carrier by a radio frequency (RF) or microwave signal can be accomplished independent of laser type when indirect modulation is employed. Indirect modulators exploit the integral relation of phase to frequency so that phase modulators can be used to impress frequency modulation on an optical carrier. The use of integrated optics phase modulators, which are highly linear, enables the generation of optical wideband FM signals with very low intermodulation distortion. This modulator can be used as part of an optical wideband FM link for RF and microwave signals. Experimental results from the test of an indirect frequency modulator for an optical carrier are discussed.

Saturn Apollo Program

NASA Image and Video Library

1970-04-01

Apollo 13 onboard photo: This view of the severely damaged Apollo 13 Service Module was photographed from the Lunar Module/Command Module following the jettison of the Service Module. As seen here, an entire panel of the Service Module was blown away by the apparent explosion of oxygen tank number two located in Sector 4 of the Service Module. Two of the three fuel cells are visible just forward (above) the heavily damaged area. Three fuel cells, two oxygen tanks, and two hydrogen tanks, are located in Sector 4. The damaged area is located above the S-band high gain anterna. Nearest the camera is the Service Propulsion System (SPS) engine and nozzle. The damage to the Service Module caused the Apollo 13 crewmen to use the Lunar Module as a lifeboat. The Lunar Module was jettisoned by the Command Module just prior to Earth re-entry.

The design and development of a rectangular, shingle-type photovoltaic module

NASA Astrophysics Data System (ADS)

Shepard, N. F., Jr.

A shingle-type photovoltaic module has been designed and developed to meet the requirements of specifications for residential applications. The module is ideally suited for installation directly to the sheathing of a sloping, south-facing roof of a residential, industrial, or commercial building. The design requirements are examined, taking into account also module safety requirements. Aspects of module design and analysis are discussed, giving attention to installation details, solar cells and electrical circuit design, the encapsulation system, substrate lamination, and the module-to-module interconnecting cable. Details of module assembly experience and test and outdoor exposure experience are also considered.

The design and development of a rectangular, shingle-type photovoltaic module

NASA Technical Reports Server (NTRS)

Shepard, N. F., Jr.

1982-01-01

A shingle-type photovoltaic module has been designed and developed to meet the requirements of specifications for residential applications. The module is ideally suited for installation directly to the sheathing of a sloping, south-facing roof of a residential, industrial, or commercial building. The design requirements are examined, taking into account also module safety requirements. Aspects of module design and analysis are discussed, giving attention to installation details, solar cells and electrical circuit design, the encapsulation system, substrate lamination, and the module-to-module interconnecting cable. Details of module assembly experience and test and outdoor exposure experience are also considered.

An auto-bias control scheme for IQ-modulator with various modulation formats

NASA Astrophysics Data System (ADS)

Zhang, Wenqi; Yuan, Xueguang; Zhang, Yang'an

2016-10-01

We propose and demonstrate an auto-bias control scheme for the IQ-modulator of a flexible optical PSK or QAM or other modulation formats transmitter in this paper. Due to IQ-modulators usually producing higher-order modulation format, these modulation formats involve phase mostly. It is based on that the bias drift will change the operating point and result in varying the output optical phase. This technology has no restrictions on modulation formats, so it has good flexibility. The experimental result show the three biases can be stabilized when the proposed scheme is implemented.

System and method for tuning adjusting the central frequency of a laser while maintaining frequency stabilization to an external reference

NASA Technical Reports Server (NTRS)

Livas, Jeffrey (Inventor); Thorpe, James I. (Inventor); Numata, Kenji (Inventor)

2011-01-01

A method and system for stabilizing a laser to a frequency reference with an adjustable offset. The method locks a sideband signal generated by passing an incoming laser beam through the phase modulator to a frequency reference, and adjusts a carrier frequency relative to the locked sideband signal by changing a phase modulation frequency input to the phase modulator. The sideband signal can be a single sideband (SSB), dual sideband (DSB), or an electronic sideband (ESB) signal. Two separate electro-optic modulators can produce the DSB signal. The two electro-optic modulators can be a broadband modulator and a resonant modulator. With a DSB signal, the method can introduce two sinusoidal phase modulations at the phase modulator. With ESB signals, the method can further drive the optical phase modulator with an electrical signal with nominal frequency OMEGA(sub 1) that is phase modulated at a frequency OMEGA(sub 2)

Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

PubMed Central

Wang, Lei; Cao, Shibin

2013-01-01

The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted. PMID:24348146

High-efficiency L-band T/R Module: Development Results

NASA Technical Reports Server (NTRS)

Edelstein, Wendy N.; Andricos, Constantine; Wang, Feiyu; Rutled, David B.

2005-01-01

Future interferometric synthetic aperture radar (InSAR) systems require electronically scanned phased-array antennas, where the transmit/receive (T/R) module is a key component. The T/R module efficiency is a critical figure of merit and has direct implications on the power dissipation and power generation requirements of the system. Significant improvements in the efficiency of the T/R module will make SAR missions more feasible and affordable. The results of two high-efficiency T/R modules are presented, each based on different power amplifier technologies. One module uses a 30W GaAs Class-AlB power amplifier and the second module uses a 70W LD-MOS Class-ElF power amplifier, where both modules use a common low power section. Each module operates over an 80MHz bandwidth at L-band (1.2GHz) with an overall module efficiency greater than 58%. We will present the results of these two T/R modules that have been designed, built and tested.

Information theory analysis of patterns of modulation in the advertisement call of the male bullfrog, Rana catesbeianaa)

PubMed Central

Suggs, Dianne N.; Simmons, Andrea Megela

2005-01-01

Male bullfrogs often amplitude modulate the envelopes of the individual notes (croaks) in their multinote advertisement calls. These amplitude modulations change the envelope of the note from smooth and unmodulated to one with varying numbers of modulations. A Markov analysis shows the pattern of change in the envelope to be highly ordered, but not completely so (semi-Markovian). Three simple rules govern the presence or absence of modulations in individual notes. These rules are (1) all calls begin with an unmodulated note; (2) the first note to be modulated will contain only one modulation; and (3) when a change in modulation occurs from one note to the next, it does so with an increase or a decrease of one modulation only. The addition of modulations is correlated with an increase in note duration. Physiologically, the presence of modulations might increase the precision of temporal coding of note periodicities in the central auditory system. PMID:15898673

Advanced space system analysis software. Technical, user, and programmer guide

NASA Technical Reports Server (NTRS)

Farrell, C. E.; Zimbelman, H. F.

1981-01-01

The LASS computer program provides a tool for interactive preliminary and conceptual design of LSS. Eight program modules were developed, including four automated model geometry generators, an associated mass properties module, an appendage synthesizer module, an rf analysis module, and an orbital transfer analysis module. The existing rigid body controls analysis module was modified to permit analysis of effects of solar pressure on orbital performance. A description of each module, user instructions, and programmer information are included.

Avionics Architecture Standards as an Approach to Obsolescence Management

DTIC Science & Technology

2000-10-01

and goals is one method of system. The term System Architecture refers to a achieving the necessary critical mass of skilled and consistent set of such...Processing Module (GPM), Mass Memory Module executed on the modules within an ASAAC system will (MMM) and Power Conversion Module (PCM). be stored in a central...location, the Mass Memory * MOS -Module Support Layer to Operating System Module (MMM). Therefore, if modules are to be The purpose of the MOS

Relative sideband amplitudes versus modulation index for common functions using frequency and phase modulation. [for design and testing of communication system

NASA Technical Reports Server (NTRS)

Stocklin, F.

1973-01-01

The equations defining the amplitude of sidebands resulting from either frequency modulation or phase modulation by either square wave, sine wave, sawtooth or triangular modulating functions are presented. Spectral photographs and computer generated tables of modulation index vs. relative sideband amplitudes are also included.

Supplemental Driver Safety Program Development Volume II--Pilot and Field Test Module Materials. Final Report.

ERIC Educational Resources Information Center

McPherson, Kenard; Weidman, James R.

This volume contains materials to supplement existing driver education programming offered by high schools to youthful (16- to 18-year old) drivers. Section I contains three drinking/driving modules: an information-only module, a self-image module, and a three-unit peer intervention module. An instructor's guide provided for each module includes…

Using Modules in an Environmental Health Training Program. Module 20. Vocational Education Training in Environmental Health Sciences.

ERIC Educational Resources Information Center

Consumer Dynamics Inc., Rockville, MD.

This module, one of 25 on vocational education training for careers in environmental health occupations, is on using modules in an environmental health training program. This informational document describes the prospective student, content and objectives of the modules, and how to select modules for use in an environmental health training…

Development and performance of pulse-width-modulated static inverter and converter modules

NASA Technical Reports Server (NTRS)

Pittman, P. F.; Gourash, F.; Birchenough, A. G.; Pittman, P. F.; Ravas, R. J.; Hall, W. G.

1971-01-01

Pulse-width-modulated inverter and converter modules are being developed for modular aerospace electrical power systems. The modules, rate 2.5 kilowatts per module and 10-minute - 150-percent overload, operate from 56 volts dc. The converter module provides two output voltages: a nominal link voltage of 200 volts dc when used with the inverter, and 150 volts dc to a load bus when used separately. The inverter module output is 400-hertz, sinusoidal, three-phase, 120/208 volts. Tests of breadboard models with standard parts and integrated circuits show rated power efficiencies of 71.4 and 85.1 percent and voltage regulation of 5 and 3.1 percent for inverter and converter modules, respectively. Sine-wave output distortion is 0.74 percent.