WorldWideScience

Sample records for electron mobilities exceeding

  1. Electronic Discharge Letter Mobile App

    NARCIS (Netherlands)

    Lezcano, Leonardo; Triana, Michel; Ternier, Stefaan; Hartkopf, Kathleen; Stieger, Lina; Schroeder, Hanna; Sopka, Sasa; Drachsler, Hendrik; Maher, Bridget; Henn, Patrick; Orrego, Carola; Marcus, Specht

    2014-01-01

    The electronic discharge letter mobile app takes advantage of Near Field Communication (NFC) within the PATIENT project and a related post-doc study. NFC enabled phones to read passive RFID tags, but can also use this short-range wireless technology to exchange (small) messages. NFC in that sense

  2. Nonlinear currents generated in plasma by a radiation pulse with a frequency exceeding the electron plasma frequency

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2016-09-15

    It is shown that the nonlinear currents generated in plasma by a radiation pulse with a frequency exceeding the electron plasma frequency change substantially due to a reduction in the effective electron–ion collision frequency.

  3. Protocols in Mobile Electronic Commerce

    OpenAIRE

    Mr. Vivek B. Patil; Mr.Deepak G. Awate

    2017-01-01

    Mobile-commerce, also known by other terms such as M-Commerce or m-Commerce, is the capability to follow commerce with the help of a hand held devise like mobile phone, a Personal digital assistant PDA, a smart phone, or other emerging mobile equipment such as dash top mobile devices. Since decade Mobile-commerce is being expressed as follows: Mobile-commerce is where any transaction, involving the transfer of rights or ownership to use goods and services, which is initialized and/or processe...

  4. The Electronic Discharge Letter Mobile App

    NARCIS (Netherlands)

    Lezcano, Leonardo; Ternier, Stefaan; Drachsler, Hendrik; Kalz, Marco; Specht, Marcus

    2013-01-01

    Lezcano, L., Ternier, S., Drachsler, H., Kalz, M., & Specht, M. (2013, September). The Electronic Discharge Letter Mobile App. In iProceedings of MEDICINE 2.0: 6th World Congress on Social Media, Mobile Apps, Internet/Web 2.0 (pp. 221-222). London, England. Retrieved from

  5. Low Energy Electronics Design for Mobile Platforms

    National Research Council Canada - National Science Library

    East, J

    2002-01-01

    In order to address the need for low-energy electronics design for mobile platforms in future Army communication systems a multidisciplinary effort is needed to investigate system and component design...

  6. 76 FR 24051 - In the Matter of Certain Electronic Devices, Including Mobile Phones, Mobile Tablets, Portable...

    Science.gov (United States)

    2011-04-29

    ... COMMISSION In the Matter of Certain Electronic Devices, Including Mobile Phones, Mobile Tablets, Portable... within the United States after importation of certain electronic devices, including mobile phones, mobile... importation of certain electronic devices, including mobile phones, mobile tablets, portable music players...

  7. Electron Mobility and Trapping in Ferrihydrite Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Soltis, Jennifer A.; Schwartzberg, Adam M.; Zarzycki, Piotr; Penn, R. Lee; Rosso, Kevin M.; Gilbert, Benjamin

    2017-05-30

    Iron is the most abundant transition metal in the Earth's crust, and naturally occurring iron oxide minerals play a commanding role in environmental redox reactions. Although iron oxide redox reactions are well studied, their precise mechanisms are not fully understood. Recent work has shown that these involve electron transfer pathways within the solid, suggesting that overall reaction rates could be dependent on electron mobility. Initial ultrafast spectroscopy studies of iron oxide nanoparticles sensitized by fluorescein derivatives supported a model for electron mobility based on polaronic hopping of electron charge carriers between iron sites, but the constitutive relationships between hopping mobilities and interfacial charge transfer processes has remained obscured. We developed a coarse-grained lattice Monte Carlo model to simulate the collective mobilities and lifetimes of these photoinjected electrons with respect to recombination with adsorbed dye molecules for the essential nanophase ferrihydrite, and tested predictions made by the simulations using pump-probe spectroscopy. We acquired optical transient absorption spectra as a function of particle size and under a variety of solution conditions, and used cryogenic transmission electron microscopy to determine the aggregation state of the nanoparticles. We observed biphasic electron recombination kinetics over timescales that spanned picoseconds to microseconds, the slower regime of which was fit with a stretched exponential decay function. The recombination rates were weakly affected by nanoparticle size and aggregation state, suspension pH, and the injection of multiple electrons per nanoparticle. We conclude that electron mobility indeed limits the rate of interfacial electron transfer in these systems with the slowest processes relating to escape from deep traps, the presence of which outweighs the influence of environmental factors such as pH-dependent surface charge.

  8. Electron mobility calculation for graphene on substrates

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, Hideki; Ogawa, Matsuto [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokko-dai, Nada-ku, Kobe 657-8501 (Japan); Tsuchiya, Hideaki, E-mail: tsuchiya@eedept.kobe-u.ac.jp [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, 1-1, Rokko-dai, Nada-ku, Kobe 657-8501 (Japan); Japan Science and Technology Agency, CREST, Chiyoda, Tokyo 102-0075 (Japan); Kamakura, Yoshinari; Mori, Nobuya [Japan Science and Technology Agency, CREST, Chiyoda, Tokyo 102-0075 (Japan); Division of Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871 (Japan)

    2014-08-28

    By a semiclassical Monte Carlo method, the electron mobility in graphene is calculated for three different substrates: SiO{sub 2}, HfO{sub 2}, and hexagonal boron nitride (h-BN). The calculations account for polar and non-polar surface optical phonon (OP) scatterings induced by the substrates and charged impurity (CI) scattering, in addition to intrinsic phonon scattering in pristine graphene. It is found that HfO{sub 2} is unsuitable as a substrate, because the surface OP scattering of the substrate significantly degrades the electron mobility. The mobility on the SiO{sub 2} and h-BN substrates decreases due to CI scattering. However, the mobility on the h-BN substrate exhibits a high electron mobility of 170 000 cm{sup 2}/(V·s) for electron densities less than 10{sup 12 }cm{sup −2}. Therefore, h-BN should be an appealing substrate for graphene devices, as confirmed experimentally.

  9. Achieving high carrier mobility exceeding 70 cm2/Vs in amorphous zinc tin oxide thin-film transistors

    Science.gov (United States)

    Kim, Sang Tae; Shin, Yeonwoo; Yun, Pil Sang; Bae, Jong Uk; Chung, In Jae; Jeong, Jae Kyeong

    2017-09-01

    This paper proposes a new defect engineering concept for low-cost In- and Ga-free zinc tin oxide (ZTO) thin-film transistors (TFTs). This concept is comprised of capping ZTO films with tantalum (Ta) and a subsequent modest thermal annealing treatment at 200 °C. The Ta-capped ZTO TFTs exhibited a remarkably high carrier mobility of 70.8 cm2/Vs, low subthreshold gate swing of 0.18 V/decade, threshold voltage of -1.3 V, and excellent ION/OFF ratio of 2 × 108. The improvement (> two-fold) in the carrier mobility compared to the uncapped ZTO TFT can be attributed to the effective reduction of the number of adverse tailing trap states, such as hydroxyl groups or oxygen interstitial defects, which stems from the scavenging effect of the Ta capping layer on the ZTO channel layer. Furthermore, the Ta-capped ZTO TFTs showed excellent positive and negative gate bias stress stabilities. [Figure not available: see fulltext.

  10. Mobile Usability of Intelligent Electronic Devices

    OpenAIRE

    Shafqat, Adnan

    2015-01-01

    Context: The Human Machine Interface (HMI) for Intelligent Electronic Devices (IEDs) is limited in its capability and is often the most common cause of failure when interacting with devices. A new approach to interact with these devices is needed with focus on improving interaction and effective visualization of information. Objectives: In this thesis, we investigate and propose a solution to visualize data of existing IED in interactive way. A mobile based prototype is proposed to list alarm...

  11. Electronic Payments using Mobile Communication Devices

    NARCIS (Netherlands)

    Waaij, B.D. van der; Siljee, B.I.J.; Broekhuijsen, B.J.; Ponsioen, C.; Maas, A.; Aten, R.M.; Hoepman, J.H.; Loon, J.H. van; Smit, M.

    2009-01-01

    A method of making a payment uses a first mobile communication device (1) and a second mobile communication device (2), each mobile communication device being provided with a respective near field communication unit (11, 21) and at least one of the mobile communication devices being provided with an

  12. Gd$^{3+}$ - Gd$^{3+}$ distances exceeding 3 nm determined by very high frequency continuous wave electron paramagnetic resonance

    CERN Document Server

    Clayton, Jessica A; Godt, Adelheid; Goldfarb, Daniella; Han, Songi; Sherwin, Mark S

    2016-01-01

    Electron paramagnetic resonance spectroscopy in combination with site-directed spin-labeling is a very powerful tool for elucidating the structure and organization of biomolecules. Gd$^{3+}$ complexes have recently emerged as a new class of spin labels for distance determination by pulsed EPR spectroscopy at Q- and W-band. We present CW EPR measurements at 240 GHz (8.6 Tesla) on a series of Gd-rulers of the type Gd-PyMTA---spacer---Gd-PyMTA, with Gd-Gd distances ranging from 1.2 nm to 4.3 nm. CW EPR measurements of these Gd-rulers show that significant dipolar broadening of the central $|-1/2\\rangle\\rightarrow|1/2\\rangle$ transition occurs at 30 K for Gd-Gd distances up to $\\sim$ 3.4 nm with Gd-PyMTA as the spin label. This represents a significant extension for distances accessible by CW EPR, as nitroxide-based spin labels at X-band frequencies can typically only access distances up to $\\sim$ 2 nm. We show that this broadening persists at biologically relevant temperatures above 200 K, and that this method i...

  13. High electron mobility and large magnetoresistance in the half-Heusler semimetal LuPtBi

    KAUST Repository

    Hou, Zhipeng

    2015-12-18

    Materials with high carrier mobility showing large magnetoresistance (MR) have recently received much attention because of potential applications in future high-performance magnetoelectric devices. Here, we report on an electron-hole-compensated half-Heusler semimetal LuPtBi that exhibits an extremely high electron mobility of up to 79000cm2/Vs with a nonsaturating positive MR as large as 3200% at 2 K. Remarkably, the mobility at 300 K is found to exceed 10500cm2/Vs, which is among the highest values reported in three-dimensional bulk materials thus far. The clean Shubnikov–de Haas quantum oscillation observed at low temperatures and the first-principles calculations together indicate that the high electron mobility is due to a rather small effective carrier mass caused by the distinctive band structure of the crystal. Our findings provide a different approach for finding large, high-mobility MR materials by designing an appropriate Fermi surface topology starting from simple electron-hole-compensated semimetals.

  14. Room temperature formation of high-mobility two-dimensional electron gases at crystalline complex oxide interfaces

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Bovet, N.; Kasama, Takeshi

    2014-01-01

    Well-controlled sub-unit-cell layer-bylayer epitaxial growth of spinel alumina is achieved at room temperature on a TiO2-terminated SrTiO3 single-crystalline substrate. By tailoring the interface redox reaction, 2D electron gases with mobilities exceeding 3000 cm 2 V−1 s−1 are achieved...

  15. The Future of the Mobile Payment as Electronic Payment System

    OpenAIRE

    Bezovski, Zlatko

    2016-01-01

    The development of the Internet and the arrival of e-commerce fostered digitalization in the payment processes by providing a variety of electronic payment options including payment cards (credit and debit), digital and mobile wallets, electronic cash, contactless payment methods etc. Mobile payment services with their increasing popularity are presently under the phase of transition, heading towards a promising future of tentative possibilities along with the innovation in technology. In thi...

  16. Innovative Mobile Platform Developments for Electronic Services Design and Delivery

    DEFF Research Database (Denmark)

    Scupola, Ada

    In the ever-growing world of technology, it is becoming more important to understand the developments of new electronic services and mobile applications. Innovative Mobile Platform Developments for Electronic Services Design, and Delivery is a comprehensive look at all aspects of production...... management, delivery and consumption of e-services, self services, and mobile communication including business-to-business, business-to-consumer, government-to-business, government-to-consumer, and consumer-to-consumer e-services. This volume is perfect for the interest of professionals, academic educators...

  17. Typical presentation to evaluate NFC technology in electronic mobile payments

    Directory of Open Access Journals (Sweden)

    Shima Asadbeigi

    2016-07-01

    Full Text Available In recent years, electronic micro payments by cell phones have been possible. Some activities have been done in this field as well. Mobile near field communication (NFC technology, which is a standard mobile method for connecting electronic devices at near distances, has grabbed a lot of attention in order to pay mobile micro payments and electronic payment services by financial institutions, payment service companies, SIM cards manufacturers and operators. The beneficiary organizations need to meet some requirements such as management preparation. This paper aims to detect different NFC technology uses and study and rank the main factors of success in implementation of this technology in organization by applying analytic hierarchy process. The humanitarian specialists and environmental and technological experts should be considered in order to use NFC technology in mobile payments. Among 81 sub-criteria, security and privacy are the most important factors for implementing NFC technology successfully.

  18. Development of mobile platform integrated with existing electronic medical records.

    Science.gov (United States)

    Kim, YoungAh; Kim, Sung Soo; Kang, Simon; Kim, Kyungduk; Kim, Jun

    2014-07-01

    This paper describes a mobile Electronic Medical Record (EMR) platform designed to manage and utilize the existing EMR and mobile application with optimized resources. We structured the mEMR to reuse services of retrieval and storage in mobile app environments that have already proven to have no problem working with EMRs. A new mobile architecture-based mobile solution was developed in four steps: the construction of a server and its architecture; screen layout and storyboard making; screen user interface design and development; and a pilot test and step-by-step deployment. This mobile architecture consists of two parts, the server-side area and the client-side area. In the server-side area, it performs the roles of service management for EMR and documents and for information exchange. Furthermore, it performs menu allocation depending on user permission and automatic clinical document architecture document conversion. Currently, Severance Hospital operates an iOS-compatible mobile solution based on this mobile architecture and provides stable service without additional resources, dealing with dynamic changes of EMR templates. The proposed mobile solution should go hand in hand with the existing EMR system, and it can be a cost-effective solution if a quality EMR system is operated steadily with this solution. Thus, we expect this example to be shared with hospitals that currently plan to deploy mobile solutions.

  19. Mobility of Electron in DNA Crystals by Laser Radiation

    Science.gov (United States)

    Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhang, Ping; Dong, Lifang

    1996-01-01

    The mobility of electrons in laser radiated DNA is closed to the energy transfer and energy migration of a biological molecule. Arrhenius has studied the conductivity of the electrons in a biological molecule. But his result is far from the experimental result and meanwhile the relation between some parameters in his theory and the micro-quantities in DNA is not very clear. In this paper, we propose a new phonon model of electron mobility in DNA and use Lippman-Schwinger equation and S-matrix theory to study the mobility of electrons in DNA crystal. The result is relatively close to the experiment result and some parameters in Arrhenius theory are explained in our work.

  20. High mobility, printable, and solution-processed graphene electronics.

    Science.gov (United States)

    Wang, Shuai; Ang, Priscilla Kailian; Wang, Ziqian; Tang, Ai Ling Lena; Thong, John T L; Loh, Kian Ping

    2010-01-01

    The ability to print graphene sheets onto large scale, flexible substrates holds promise for large scale, transparent electronics on flexible substrates. Solution processable graphene sheets derived from graphite can form stable dispersions in solutions and are amenable to bulk scale processing and ink jet printing. However, the electrical conductivity and carrier mobilities of this material are usually reported to be orders of magnitude poorer than that of the mechanically cleaved counterpart due to its higher density of defects, which restricts its use in electronics. Here, we show that by optimizing several key factors in processing, we are able to fabricate high mobility graphene films derived from large sized graphene oxide sheets, which paves the way for all-carbon post-CMOS electronics. All-carbon source-drain channel electronics fabricated from such films exhibit significantly improved transport characteristics, with carrier mobilities of 365 cm(2)/(V.s) for hole and 281 cm(2)/(V.s) for electron, measured in air at room temperature. In particular, intrinsic mobility as high as 5000 cm(2)/(V.s) can be obtained from such solution-processed graphene films when ionic screening is applied to nullify the Coulombic scattering by charged impurities.

  1. Electronic Voting System using Mobile Terminal

    OpenAIRE

    Keonwoo Kim; Dowon Hong

    2007-01-01

    Electronic voting (E-voting) using an internet has been recently performed in some nations and regions. There is no spatial restriction which a voter directly has to visit the polling place, but an e-voting using an internet has to go together the computer in which the internet connection is possible. Also, this voting requires an access code for the e-voting through the beforehand report of a voter. To minimize these disadvantages, we propose a method in which a voter, w...

  2. Travel in Adverse Weather Using Electronic Mobility Guidance Devices

    Science.gov (United States)

    Farmer, Leicester W.

    1975-01-01

    After a discussion of the required characteristics of an ideal aid for blind individuals traveling in adverse weather, four electronic mobility guidance devices- the Mowat Sonar Sensor, the Russell E Model Pathsounder, the Bionic C-5 Laser Cane, and the Mark II Binaural Sensory Aid-are described in detail. (Author/SB)

  3. The Use of Mobile Electronic Devices for Public Health Data ...

    African Journals Online (AJOL)

    The report compliance rate was 89% for daily SMS and 100% for weekly SMS versus 76% for weekly paper reports. Electronic data collection and reporting is feasible and cost-efficient in low-resource settings. Keywords: mobile phones, text messaging, database management systems, census methods, sentinelsurveillance ...

  4. The Development of an Indoor Mobility Course for the Evaluation of Electronic Mobility Aids for Persons Who Are Visually Impaired

    Science.gov (United States)

    Roentgen, Uta R.; Gelderblom, Gert Jan; de Witte, Luc P.

    2012-01-01

    Purpose: To develop a suitable mobility course for the assessment of mobility performance as part of a user evaluation of Electronic Mobility Aids (EMA) aimed at obstacle detection and orientation. Method: A review of the literature led to a list of critical factors for the assessment of mobility performance of persons who are visually impaired.…

  5. Structured back gates for high-mobility two-dimensional electron systems using oxygen ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Berl, M., E-mail: mberl@phys.ethz.ch; Tiemann, L.; Dietsche, W.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland); Karl, H. [Lehrstuhl für Experimentalphysik IV, Universität Augsburg, 86159 Augsburg (Germany)

    2016-03-28

    We present a reliable method to obtain patterned back gates compatible with high mobility molecular beam epitaxy via local oxygen ion implantation that suppresses the conductivity of an 80 nm thick silicon doped GaAs epilayer. Our technique was optimized to circumvent several constraints of other gating and implantation methods. The ion-implanted surface remains atomically flat which allows unperturbed epitaxial overgrowth. We demonstrate the practical application of this gating technique by using magneto-transport spectroscopy on a two-dimensional electron system (2DES) with a mobility exceeding 20 × 10{sup 6} cm{sup 2}/V s. The back gate was spatially separated from the Ohmic contacts of the 2DES, thus minimizing the probability for electrical shorts or leakage and permitting simple contacting schemes.

  6. Modelling of snow exceedances

    Science.gov (United States)

    Jordanova, Pavlina K.; Sadovský, Zoltán; Stehlík, Milan

    2017-07-01

    Modelling of snow exceedances is of great importance and interest for ecology, civil engineering and general public. We suggest the favorable fit for exceedances related to the exceptional snow loads from Slovakia, assuming that the data is driven by Generalised Pareto Distribution or Generalized Extreme Value Distribution. Further, the statistical dependence between the maximal snow loads and the corresponding altitudes is studied.

  7. Organic High Electron Mobility Transistors Realized by 2D Electron Gas.

    Science.gov (United States)

    Zhang, Panlong; Wang, Haibo; Yan, Donghang

    2017-09-01

    A key breakthrough in inorganic modern electronics is the energy-band engineering that plays important role to improve device performance or develop novel functional devices. A typical application is high electron mobility transistors (HEMTs), which utilizes 2D electron gas (2DEG) as transport channel and exhibits very high electron mobility over traditional field-effect transistors (FETs). Recently, organic electronics have made very rapid progress and the band transport model is demonstrated to be more suitable for explaining carrier behavior in high-mobility crystalline organic materials. Therefore, there emerges a chance for applying energy-band engineering in organic semiconductors to tailor their optoelectronic properties. Here, the idea of energy-band engineering is introduced and a novel device configuration is constructed, i.e., using quantum well structures as active layers in organic FETs, to realize organic 2DEG. Under the control of gate voltage, electron carriers are accumulated and confined at quantized energy levels, and show efficient 2D transport. The electron mobility is up to 10 cm 2 V -1 s -1 , and the operation mechanisms of organic HEMTs are also argued. Our results demonstrate the validity of tailoring optoelectronic properties of organic semiconductors by energy-band engineering, offering a promising way for the step forward of organic electronics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Effect of electron-electron interaction on cyclotron resonance in high-mobility InAs/AlSb quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Krishtopenko, S. S., E-mail: sergey.krishtopenko@mail.ru; Gavrilenko, V. I. [Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105 (Russian Federation); Lobachevsky State University, 23 Prospekt Gagarina, 603950 Nizhny Novgorod (Russian Federation); Ikonnikov, A. V. [Institute for Physics of Microstructures, Russian Academy of Sciences, 603950 Nizhny Novgorod, GSP-105 (Russian Federation); Orlita, M. [Laboratoire National des Champs Magnétiques Intenses (LNCMI-G), CNRS, 25 rue des Martyrs, B.P. 166, 38042 Grenoble (France); Sadofyev, Yu. G. [P.N. Lebedev Physical Institute, Russian Academy of Sciences, Moscow 119991, GSP-1, 53 Leninskiy Prospect (Russian Federation); Goiran, M. [Laboratoire National des Champs Magnétiques Intenses (LNCMI-T), CNRS, 143 Avenue de Rangueil, 31400 Toulouse (France); Teppe, F.; Knap, W. [Laboratoire Charles Coulomb (L2C), UMR CNRS 5221, GIS-TERALAB, Universite Montpellier II, 34095 Montpellier (France)

    2015-03-21

    We report observation of electron-electron (e-e) interaction effect on cyclotron resonance (CR) in InAs/AlSb quantum well heterostructures. High mobility values allow us to observe strongly pronounced triple splitting of CR line at noninteger filling factors of Landau levels ν. At magnetic fields, corresponding to ν > 4, experimental values of CR energies are in good agreement with single-electron calculations on the basis of eight-band k ⋅ p Hamiltonian. In the range of filling factors 3 < ν < 4 pronounced, splitting of CR line, exceeding significantly the difference in single-electron CR energies, is discovered. The strength of the splitting increases when occupation of the partially filled Landau level tends to a half, being in qualitative agreement with previous prediction by MacDonald and Kallin [Phys. Rev. B 40, 5795 (1989)]. We demonstrate that such behaviour of CR modes can be quantitatively described if one takes into account both electron correlations and the mixing between conduction and valence bands in the calculations of matrix elements of e-e interaction.

  9. 77 FR 27078 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...

    Science.gov (United States)

    2012-05-08

    ... Trade Commission has received a complaint entitled Certain Electronic Devices, Including Mobile Phones... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...

  10. Patent Analysis of Power Electronic Technologies for Electric Mobility

    OpenAIRE

    Frieske, Benjamin; Yen, Ching-te

    2014-01-01

    This paper examines the research landscape for automotive power electronics as key technology for electric mobility in a time frame from 2000 until 2012 by conducting in-depth patent and publication analyses. Using complex and dedicated search strategies, more than 3,800 peer-reviewed scientific publications and 47,000 patent applications in 6 different world regions could be identified. With the help of automated text and data mining functionalities, the evaluation of patent and publication ...

  11. Patterning of high mobility electron gases at complex oxide interfaces

    DEFF Research Database (Denmark)

    Trier, Felix; Prawiroatmodjo, G. E. D. K.; von Soosten, Merlin

    2015-01-01

    Oxide interfaces provide an opportunity for electronics. However, patterning of electron gases at complex oxide interfaces is challenging. In particular, patterning of complex oxides while preserving a high electron mobility remains underexplored and inhibits the study of quantum mechanical effects...... where extended electron mean free paths are paramount. This letter presents an effective patterning strategy of both the amorphous-LaAlO3/SrTiO3 (a-LAO/STO) and modulation-doped amorphous-LaAlO3/La7/8Sr1/8MnO3/SrTiO3 (a-LAO/LSM/STO) oxide interfaces. Our patterning is based on selective wet etching...... of amorphous-LSM (a-LSM) thin films, which acts as a hard mask during subsequent depositions. Strikingly, the patterned modulation-doped interface shows electron mobilities up to ∼8 700 cm2/V s at 2 K, which is among the highest reported values for patterned conducting complex oxide interfaces that usually...

  12. 77 FR 18860 - Certain Consumer Electronics, Including Mobile Phones and Tablets; Notice of Receipt of Complaint...

    Science.gov (United States)

    2012-03-28

    ... COMMISSION Certain Consumer Electronics, Including Mobile Phones and Tablets; Notice of Receipt of Complaint... complaint entitled Certain Consumer Electronics, Including Mobile Phones and Tablets, DN 2885; the... importation of certain consumer electronics, including mobile phones and tablets. The complaint names as...

  13. Creation of High Mobility Two-Dimensional Electron Gases via Strain Induced Polarization at an Otherwise Nonpolar Complex Oxide Interface

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Trier, Felix; Kasama, Takeshi

    2015-01-01

    The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based heterostructures provides new opportunities for nanoelectronics. Herein, we create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Rem....... Remarkably, this heterointerface is atomically sharp and exhibits a high electron mobility exceeding 60 000 cm2 V−1 s−1 at low temperatures. The 2DEG carrier density exhibits a critical dependence on the film thickness, in good agreement with the polarization induced 2DEG scheme....

  14. Shutterless ion mobility spectrometer with fast pulsed electron source

    Science.gov (United States)

    Bunert, E.; Heptner, A.; Reinecke, T.; Kirk, A. T.; Zimmermann, S.

    2017-02-01

    Ion mobility spectrometers (IMS) are devices for fast and very sensitive trace gas analysis. The measuring principle is based on an initial ionization process of the target analyte. Most IMS employ radioactive electron sources, such as 63Ni or 3H. These radioactive materials have the disadvantage of legal restrictions and the electron emission has a predetermined intensity and cannot be controlled or disabled. In this work, we replaced the 3H source of our IMS with 100 mm drift tube length with our nonradioactive electron source, which generates comparable spectra to the 3H source. An advantage of our emission current controlled nonradioactive electron source is that it can operate in a fast pulsed mode with high electron intensities. By optimizing the geometric parameters and developing fast control electronics, we can achieve very short electron emission pulses for ionization with high intensities and an adjustable pulse width of down to a few nanoseconds. This results in small ion packets at simultaneously high ion densities, which are subsequently separated in the drift tube. Normally, the required small ion packet is generated by a complex ion shutter mechanism. By omitting the additional reaction chamber, the ion packet can be generated directly at the beginning of the drift tube by our pulsed nonradioactive electron source with only slight reduction in resolving power. Thus, the complex and costly shutter mechanism and its electronics can also be omitted, which leads to a simple low-cost IMS-system with a pulsed nonradioactive electron source and a resolving power of 90.

  15. 77 FR 34063 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...

    Science.gov (United States)

    2012-06-08

    ... COMMISSION Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof... devices, including mobile phones and tablet computers, and components thereof by reason of infringement of... certain electronics devices, including mobile phones and tablet computers, and components thereof that...

  16. 75 FR 4583 - In the Matter of: Certain Electronic Devices, Including Mobile Phones, Portable Music Players...

    Science.gov (United States)

    2010-01-28

    ... COMMISSION In the Matter of: Certain Electronic Devices, Including Mobile Phones, Portable Music Players, and... electronic devices, including mobile phones, portable music players, and computers, by reason of infringement... mobile phones, portable music players, or computers that infringe one or more of claims 1-12 of U.S...

  17. Mobile agent application and integration in electronic anamnesis system.

    Science.gov (United States)

    Liu, Chia-Hui; Chung, Yu-Fang; Chen, Tzer-Shyong; Wang, Sheng-De

    2012-06-01

    Electronic anamnesis is to transform ordinary paper trails to digitally formatted health records, which include the patient's general information, health status, and follow-ups on chronic diseases. Its main purpose is to let the records could be stored for a longer period of time and could be shared easily across departments and hospitals. Which means hospital management could use less resource on maintaining ever-growing database and reduce redundancy, so less money would be spent for managing the health records. In the foreseeable future, building up a comprehensive and integrated medical information system is a must, because it is critical to hospital resource integration and quality improvement. If mobile agent technology is adopted in the electronic anamnesis system, it would help the hospitals to make the medical practices more efficiently and conveniently. Nonetheless, most of the hospitals today are still using paper-based health records to manage the medical information. The reason why the institutions continue using traditional practices to manage the records is because there is no well-trusted and reliable electronic anamnesis system existing and accepted by both institutions and patients. The threat of privacy invasion is one of the biggest concerns when the topic of electronic anamnesis is brought up, because the security threats drag us back from using such a system. So, the medical service quality is difficult to be improved substantially. In this case, we have come up a theory to remove such security threats and make electronic anamnesis more appealing for use. Our theory is to integrate the mobile agent technology with the backbone of electronic anamnesis to construct a hierarchical access control system to retrieve the corresponding information based upon the permission classes. The system would create a classification for permission among the users inside the medical institution. Under this framework, permission control center would distribute an

  18. 77 FR 24514 - Certain Consumer Electronics, Including Mobile Phones and Tablets; Institution of Investigation...

    Science.gov (United States)

    2012-04-24

    ... COMMISSION Certain Consumer Electronics, Including Mobile Phones and Tablets; Institution of Investigation... consumer electronics, including mobile phones and tablets, by reason of infringement of certain claims of U... importation, or the sale within the United States after importation of certain consumer electronics, including...

  19. 78 FR 23593 - Certain Mobile Electronic Devices Incorporating Haptics; Termination of Investigation

    Science.gov (United States)

    2013-04-19

    ... COMMISSION Certain Mobile Electronic Devices Incorporating Haptics; Termination of Investigation AGENCY: U.S... within the United States after importation of certain mobile electronic devices incorporating haptics....usitc.gov . The public record for this investigation may be viewed on the Commission's electronic docket...

  20. ATLAS: Exceeding all expectations

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    “One year ago it would have been impossible for us to guess that the machine and the experiments could achieve so much so quickly”, says Fabiola Gianotti, ATLAS spokesperson. The whole chain – from collision to data analysis – has worked remarkably well in ATLAS.   The first LHC proton run undoubtedly exceeded expectations for the ATLAS experiment. “ATLAS has worked very well since the beginning. Its overall data-taking efficiency is greater than 90%”, says Fabiola Gianotti. “The quality and maturity of the reconstruction and simulation software turned out to be better than we expected for this initial stage of the experiment. The Grid is a great success, and right from the beginning it has allowed members of the collaboration all over the world to participate in the data analysis in an effective and timely manner, and to deliver physics results very quickly”. In just a few months of data taking, ATLAS has observed t...

  1. Enhancing the Electron Mobility via Delta-Doping in SrTiO3

    Energy Technology Data Exchange (ETDEWEB)

    Kozuka, Y.

    2011-08-11

    We fabricated high-mobility {delta}-doped structures in SrTiO{sub 3} thin films in order to investigate the low temperature electronic transport properties of confined carriers in this system. An enhancement of the electron mobility above the bulk value was observed as the doped layer thickness decreased. High-field Hall measurements revealed that this mobility enhancement originates from higher-mobility electrons in the undoped clean regions, which have quantum-mechanically broadened from the doped layer. Because of the absence of apparent lattice misfit between the layers, this structure is highly suitable for investigating two-dimensional electron gases in SrTiO{sub 3}

  2. Usability in Mobile Electronic Data Collection Tools: Form Developers' Views.

    Science.gov (United States)

    Mugisha, Alice; Babic, Ankica; Wakholi, Peter; Nankabirwa, Victoria; Tylleskar, Thorkild

    2017-01-01

    Mobile Electronic Data Collection Tools (MEDCTs) are created by form developers to collect data. Usability being one of the top quality attributes is of great concern to developers of any interactive applications. However, little is known about the form developers' understanding of usability, how they measure usability and their limitations in designing for usability. We conducted an empirical study where we aimed at getting the developers' views on usability by interviewing 8 form developers. These are creators of forms used for data collection. We found that developers knew about usability, but it was not their main focus during form development. Challenges included constraining deadlines, software limitations and the insufficient communication with the field users to establish the usability needs. Furthermore, the methods used to evaluate the usability of created forms varied amongst developers and these included in-house evaluations and feedback from piloting sessions with end users.

  3. Inverted polymer fullerene solar cells exceeding 10% efficiency with poly(2-ethyl-2-oxazoline) nanodots on electron-collecting buffer layers

    Science.gov (United States)

    Nam, Sungho; Seo, Jooyeok; Woo, Sungho; Kim, Wook Hyun; Kim, Hwajeong; Bradley, Donal D. C.; Kim, Youngkyoo

    2015-12-01

    Polymer solar cells have been spotlighted due to their potential for low-cost manufacturing but their efficiency is still less than required for commercial application as lightweight/flexible modules. Forming a dipole layer at the electron-collecting interface has been suggested as one of the more attractive approaches for efficiency enhancement. However, only a few dipole layer material types have been reported so far, including only one non-ionic (charge neutral) polymer. Here we show that a further neutral polymer, namely poly(2-ethyl-2-oxazoline) (PEOz) can be successfully used as a dipole layer. Inclusion of a PEOz layer, in particular with a nanodot morphology, increases the effective work function at the electron-collecting interface within inverted solar cells and thermal annealing of PEOz layer leads to a state-of-the-art 10.74% efficiency for single-stack bulk heterojunction blend structures comprising poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-alt-3-fluorothieno[3,4-b]thiophene-2-carboxylate] as donor and [6,6]-phenyl-C71-butyric acid methyl ester as acceptor.

  4. First-principles method for electron-phonon coupling and electron mobility

    DEFF Research Database (Denmark)

    Gunst, Tue; Markussen, Troels; Stokbro, Kurt

    2016-01-01

    -band relaxation time approximation for the linearized Boltzmann transport equation (BTE) that includes inelastic scattering processes. The bulk electron-phonon coupling is evaluated by a supercell method. The method employed is fully numerical and does therefore not require a semianalytic treatment of part...... of the problem and, importantly, it keeps the anisotropy information stored in the coupling as well as the band structure. In addition, we perform calculations of the low-field mobility and its dependence on carrier density and temperature to obtain a better understanding of transport in graphene, silicene......, and monolayer MoS2. Unlike graphene, the carriers in silicene show strong interaction with the out-of-plane modes. We find that graphene has more than an order of magnitude higher mobility compared to silicene in the limit where the silicene out-of-plane interaction is reduced to zero (by substrate interaction...

  5. Electrorecycling of Critical and Value Metals from Mobile Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Lister, Tedd E.; Wang, Peming; Anderko, Andre

    2014-09-01

    Mobile electronic devices such as smart phones and tablets are a significant source of valuable metals that should be recycled. Each year over a billion devices are sold world-wide and the average life is only a couple years. Value metals in phones are gold, palladium, silver, copper, cobalt and nickel. Devices now contain increasing amounts of rare earth elements (REE). In recent years the supply chain for REE has moved almost exclusively to China. They are contained in displays, speakers and vibrators within the devices. By US Department of Energy (DOE) classification, specific REEs (Nd, Dy, Eu, Tb and Y) are considered critical while others (Ce, La and Pr) are deemed near critical. Effective recycling schemes should include the recovery of these critical materials. By including more value materials in a recovery scheme, more value can be obtained by product diversification and less waste metals remains to be disposed of. REEs are mined as a group such that when specific elements become critical significantly more ore must be processed to capture the dilute but valuable critical elements. Targeted recycling of items containing the more of the less available critical materials could address their future criticality. This presentation will describe work in developing aqueous electrochemistry-based schemes for recycling metals from scrap mobile electronics. The electrorecycling process generates oxidizing agents at an anode while reducing dissolved metals at the cathode. E vs pH diagrams and metals dissolution experiments are used to assess effectiveness of various solution chemistries. Although several schemes were envisioned, a two stages process has been the focus of work: 1) initial dissolution of Cu, Sn, Ag and magnet materials using Fe+3 generated in acidic sulfate and 2) final dissolution of Pd and Au using Cl2 generated in an HCl solution. Experiments were performed using simulated metal mixtures. Both Cu and Ag were recovered at ~ 97% using Fe+3 while

  6. High Performance Ambipolar Diketopyrrolopyrrole-Thieno[3,2-b]thiophene Copolymer Field-Effect Transistors with Balanced Hole and Electron Mobilities

    DEFF Research Database (Denmark)

    Chen, Zhuoying; Lee, Mi Jung; Ashraf, Raja Shahid

    2012-01-01

    Ambipolar OFETs with balanced hole and electron field-effect mobilities both exceeding 1 cm2 V−1 s−1 are achieved based on a single-solution-processed conjugated polymer, DPPT-TT, upon careful optimization of the device architecture, charge injection, and polymer processing. Such high-performance......-performance OFETs are promising for applications in ambipolar devices and integrated circuits, as well as model systems for fundamental studies....

  7. 78 FR 13895 - Certain Consumer Electronics, Including Mobile Phones and Tablets; Commission Determination Not...

    Science.gov (United States)

    2013-03-01

    ... COMMISSION Certain Consumer Electronics, Including Mobile Phones and Tablets; Commission Determination Not To... importation, or sale within the United States after importation of certain consumer electronics, including...''); LG Electronics, Inc. of Seoul, Republic of Korea, LG Electronics U.S.A., Inc. of Englewood Cliffs...

  8. Investigation of electron mobility and saturation velocity limits in gallium nitride using uniaxial dielectric continuum model

    Science.gov (United States)

    Park, K.; Stroscio, M. A.; Bayram, C.

    2017-06-01

    Here we introduce a uniaxial dielectric continuum model with temperature-dependent phonon mode frequencies to study temperature- and orientation-dependent polar-optical-phonon limited electron mobility and saturation velocity in uniaxial semiconductors. The formalism for calculating electron scattering rates, momentum relaxation rates, and rate of energy change as a function of the electron kinetic energy and incident electron angle with respect to the c-axis are presented and evaluated numerically. Electron-longitudinal-optical-phonon interactions are shown to depend weakly on the electron incident angle, whereas the electron-transverse-optical-phonon interactions around the emission threshold energy are observed to depend strongest on the electron incident angle when varied from π/4 to π/2 (with respect to the c-axis). We provide electron mobility and saturation velocity limits in different GaN crystal orientations as a function of temperature and electron concentration. At room temperature and for an electron density of 5 × 1018 cm-3, electron mobility limit of ˜3200 cm2/V s and electron saturation velocity limit of 3.15 × 107 cm/s are calculated. Both GaN electron mobility and saturation velocity are observed to be governed by the longitudinal-optical-phonon interaction, and their directional anisotropy is shown to vary less than 5% as the electron incident angle with respect to the c-axis is varied from 0 to π/2. Overall, we develop a theoretical formalism for calculating anisotropic properties of uniaxial wurtzite semiconductors.

  9. Indolo-naphthyridine-6,13-dione Thiophene Building Block for Conjugated Polymer Electronics: Molecular Origin of Ultrahigh n-Type Mobility

    KAUST Repository

    Fallon, Kealan J.

    2016-10-18

    Herein, we present the synthesis and characterization of four conjugated polymers containing a novel chromophore for organic electronics based on an indigoid structure. These polymers exhibit extremely small band gaps of ∼1.2 eV, impressive crystallinity, and extremely high n-type mobility exceeding 3 cm V s. The n-type charge carrier mobility can be correlated with the remarkably high crystallinity along the polymer backbone having a correlation length in excess of 20 nm. Theoretical analysis reveals that the novel polymers have highly rigid nonplanar geometries demonstrating that backbone planarity is not a prerequisite for either narrow band gap materials or ultrahigh mobilities. Furthermore, the variation in backbone crystallinity is dependent on the choice of comonomer. OPV device efficiencies up to 4.1% and charge photogeneration up to 1000 nm are demonstrated, highlighting the potential of this novel chromophore class in high-performance organic electronics.

  10. Temperature dependence of electron mobility in N-type organic molecular crystals: Theoretical study

    Science.gov (United States)

    Lin, Lili; Fan, Jianzhong; Jiang, Supu; Wang, Zhongjie; Wang, Chuan-Kui

    2017-11-01

    The temperature dependence of electron mobility in three Fx-TCNQ molecular crystals is studied. The electron mobility calculated based on Marcus charge transfer rate for all three molecules increases, as the temperature becomes high. Nevertheless, the electron mobility calculated based on quantum charge transfer rate shows opposite temperature dependence and indicates bandlike transport mechanism. Similar intrinsic transport properties are obtained for three systems. The different temperature dependence for Fx-TCNQ molecules detected should be induced by different transfer paths or external factors. Our investigation could help one better understand experimental results and provide intuitive view on the transfer mechanism in molecular crystals.

  11. Lead Halide Perovskites as Charge Generation Layers for Electron Mobility Measurement in Organic Semiconductors.

    Science.gov (United States)

    Love, John A; Feuerstein, Markus; Wolff, Christian M; Facchetti, Antonio; Neher, Dieter

    2017-12-06

    Hybrid lead halide perovskites are introduced as charge generation layers (CGLs) for the accurate determination of electron mobilities in thin organic semiconductors. Such hybrid perovskites have become a widely studied photovoltaic material in their own right, for their high efficiencies, ease of processing from solution, strong absorption, and efficient photogeneration of charge. Time-of-flight (ToF) measurements on bilayer samples consisting of the perovskite CGL and an organic semiconductor layer of different thickness are shown to be determined by the carrier motion through the organic material, consistent with the much higher charge carrier mobility in the perovskite. Together with the efficient photon-to-electron conversion in the perovskite, this high mobility imbalance enables electron-only mobility measurement on relatively thin application-relevant organic films, which would not be possible with traditional ToF measurements. This architecture enables electron-selective mobility measurements in single components as well as bulk-heterojunction films as demonstrated in the prototypical polymer/fullerene blends. To further demonstrate the potential of this approach, electron mobilities were measured as a function of electric field and temperature in an only 127 nm thick layer of a prototypical electron-transporting perylene diimide-based polymer, and found to be consistent with an exponential trap distribution of ca. 60 meV. Our study furthermore highlights the importance of high mobility charge transporting layers when designing perovskite solar cells.

  12. Usability of the Stylus Pen in Mobile Electronic Documentation

    Directory of Open Access Journals (Sweden)

    Eunil Park

    2015-11-01

    Full Text Available Stylus pens are often used with mobile information devices. However, few studies have examined the stylus’ simple movements because the technical expertise to support documentation with stylus pens has not been developed. This study examined the usability of stylus pens in authentic documentation tasks, including three main tasks (sentence, table, and paragraph making with two types of styluses (touchsmart stylus and mobile stylus and a traditional pen. The statistical results showed that participants preferred the traditional pen in all criteria. Because of inconvenient hand movements, the mobile stylus was the least preferred on every task. Mobility does not provide any advantage in using the stylus. In addition, the study also found inconvenient hand support using a stylus and different feedback between a stylus and a traditional pen.

  13. The electronic Discharge Letter Mobile App - The London man who went to the Tokio Olympics

    NARCIS (Netherlands)

    Lezcano, Leonardo; Ternier, Stefaan; Drachsler, Hendrik; Kalz, Marco; Specht, Marcus

    2013-01-01

    Lezcano, L., Ternier, S., Drachsler, H., Kalz, M., & Specht, M. (2013, September). The Electronic Discharge Letter Mobile App - The London man who went to the Tokio Olympics. Presentation at MEDICINE 2.0: 6th World Congress on Social Media, Mobile Apps, Internet/Web 2.0, London, England.

  14. Early Experiences with Mobile Electronic Health Records Application in a Tertiary Hospital in Korea.

    Science.gov (United States)

    Choi, Wookjin; Park, Minah; Hong, Eunseok; Kim, Sunhyu; Ahn, Ryeok; Hong, Jungseok; Song, Seungyeol; Kim, Tak; Kim, Jeongkeun; Yeo, Seongwoon

    2015-10-01

    Recent advances in mobile technology have opened up possibilities to provide strongly integrated mobile-based services in healthcare and telemedicine. Although the number of mobile Electronic Health Record (EHR) applications is large and growing, there is a paucity of evidence demonstrating the usage patterns of these mobile applications by healthcare providers. This study aimed to illustrate the deployment process for an integrated mobile EHR application and to analyze usage patterns after provision of the mobile EHR service. We developed an integrated mobile application that aimed to enhance the mobility of healthcare providers by improving access to patient- and hospital-related information during their daily medical activities. The study included mobile EHR users who accessed patient healthcare records between May 2013 and May 2014. We performed a data analysis using a web server log file analyzer from the integrated EHR system. Cluster analysis was applied to longitudinal user data based on their application usage pattern. The mobile EHR service named M-UMIS has been in service since May 2013. Every healthcare provider in the hospital could access the mobile EHR service and view the medical charts of their patients. The frequency of using services and network packet transmission on the M-UMIS increased gradually during the study period. The most frequently accessed service in the menu was the patient list. A better understanding regarding the adoption of mobile EHR applications by healthcare providers in patient-centered care provides useful information to guide the design and implementation of future applications.

  15. 77 FR 15390 - Certain Mobile Electronic Devices Incorporating Haptics; Receipt of Amended Complaint...

    Science.gov (United States)

    2012-03-15

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Mobile Electronic Devices Incorporating Haptics; Receipt of Amended Complaint; Solicitation of Comments Relating to the Public Interest AGENCY: U.S. International Trade Commission. ACTION...

  16. Electron mobility of inverted InAs/GaSb quantum well structure

    Science.gov (United States)

    Huang, Wenjun; Ma, Wenquan; Huang, Jianliang; Zhang, Yanhua; Cao, Yulian; Zhao, Chengcheng; Guo, Xiaolu

    2017-11-01

    We report on the electron mobility of an inverted and a non-inverted type II InAs/GaSb quantum well (QW) structures. It is found that the inverted QW, which has much thicker well width than the non-inverted one, has a smaller electron mobility than the non-inverted one for a wide range of temperature. The result disagrees with the established understanding that the electron mobility increases with increasing the QW width at very low temperature. The smaller mobility is caused by larger electron effective mass since the bottom of the conduction band of the inverted QW becomes a hole-like band due to the mixing between the conduction band and the valence band.

  17. Two-Dimensional Modeling of Aluminum Gallium Nitride/Gallium Nitride High Electron Mobility Transistor

    National Research Council Canada - National Science Library

    Holmes, Kenneth

    2002-01-01

    Gallium Nitride (GaN) High Electron Mobility Transistors (HEMT's) are microwave power devices that have the performance characteristics to improve the capabilities of current and future Navy radar and communication systems...

  18. Research on mobile electronic commerce security technology based on WPKI

    Science.gov (United States)

    Zhang, Bo

    2013-07-01

    Through the in-depth study on the existing mobile e-commerce and WAP protocols, this paper presents a security solution of e-commerce system based on WPKI, and describes its implementation process and specific implementation details. This solution uniformly distributes the key used by the various participating entities , to fully ensure the confidentiality, authentication, fairness and integrity of mobile e-commerce payments, therefore has some pract ical value for improving the security of e-commerce system.

  19. Carrier mobilities in graded InxGa1 - xAs/Al0.2Ga0.8As quantum wells for high electron mobility transistors

    Science.gov (United States)

    Strauß, U.; Bernklau, D.; Riechert, H.; Finkbeiner, S.

    1996-07-01

    We investigate modulation-doped InxGa1-xAs/AlyGa1-yAs quantum wells grown by molecular beam epitaxy with respect to carrier mobility and its dependence on In content, In distribution, populations of electron subbands, and local positions of electron wave functions. We find that the room-temperature electron mobilities are dominated by the In contents at the maxima of the electron wave functions rather than by the average In contents. At 77 K the mobilities are most strongly influenced by the distance between doping layers and the maxima of the electron wave functions. As a practical result of this study, we present a quantum well structure for high electron mobility transistors with a carrier mobility as high as 8100 cm2/V s at 295 K for an electron density of 2.5×1012 cm-2.

  20. Degradation and annealing effects caused by oxygen in AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, R., E-mail: rong.jiang@vanderbilt.edu; Chen, J.; Duan, G. X.; Zhang, E. X.; Schrimpf, R. D. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennesse 37235 (United States); Shen, X. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennesse 37235 (United States); Department of Physics and Materials Science, University of Memphis, Memphis, Tennesse 38152 (United States); Fleetwood, D. M. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennesse 37235 (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennesse 37235 (United States); Kaun, S. W.; Kyle, E. C. H.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Pantelides, S. T. [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennesse 37235 (United States); Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennesse 37235 (United States)

    2016-07-11

    Hot-carrier degradation and room-temperature annealing effects are investigated in unpassivated ammonia-rich AlGaN/GaN high electron mobility transistors. Devices exhibit a fast recovery when annealed after hot carrier stress with all pins grounded. The recovered peak transconductance can exceed the original value, an effect that is not observed in control passivated samples. Density functional theory calculations suggest that dehydrogenation of pre-existing O{sub N}-H defects in AlGaN plays a significant role in the observed hot carrier degradation, and the resulting bare O{sub N} can naturally account for the “super-recovery” in the peak transconductance.

  1. The Influence of Usability on Electronic Customer Relationship Management Performance in Jordan Mobile Phone Services

    OpenAIRE

    Samsudin Wahab; Jefry Elias; Khaled Abed Mufleh Al Momani; Nor Azila Mohd Noor

    2011-01-01

    Electronic Customer Relationship Management performance is a comprehensive business and marketing strategy that integrates people, process, technology and all business activities for attracting and retaining customers over the internet and mobile phone to reduce costs and increase profitability by consolidation the principles of customer loyalty. Therefore, the results of Electronic Customer Relationship Management performance are repeat purchase, word of mouth, retention, cross buying, brand...

  2. Interface Roughness Fractality Effects on the Electron Mobility in Semiconducting Quantum Wells

    NARCIS (Netherlands)

    Palasantzas, G.; Barnaś, J.

    1998-01-01

    The influence of interface electron scattering on electron mobility in semiconducting quantum wells is analyzed theoretically in the Born approximation. The interface roughness is assumed to be random self-affine fractal characterized by roughness exponent H, correlation length ξ, and rms amplitude

  3. Fundamental limits on the electron mobility of β-Ga2O3

    Science.gov (United States)

    Kang, Youngho; Krishnaswamy, Karthik; Peelaers, Hartwin; Van de Walle, Chris G.

    2017-06-01

    We perform first-principles calculations to investigate the electronic and vibrational spectra and the electron mobility of β-Ga2O3. We calculate the electron-phonon scattering rate of the polar optical phonon modes using the Vogl model in conjunction with Fermi’s golden rule; this enables us to fully take the anisotropic phonon spectra of the monoclinic lattice of β-Ga2O3 into account. We also examine the scattering rate due to ionized impurities or defects using a Yukawa-potential-based model. We consider scattering due to donor impurities, as well as the possibility of compensation by acceptors such as Ga vacancies. We then calculate the room-temperature mobility of β-Ga2O3 using the Boltzmann transport equation within the relaxation time approximation, for carrier densities in the range from 1017 to 1020 cm-3. We find that the electron-phonon interaction dominates the mobility for carrier densities of up to 1019 cm-3. We also find that the intrinsic anisotropy in the mobility is small; experimental findings of large anisotropy must therefore be attributed to other factors. We attribute the experimentally observed reduction of the mobility with increasing carrier density to increasing levels of compensation, which significantly affect the mobility.

  4. Charge carrier mobility and electronic properties of Al(Op3: impact of excimer formation

    Directory of Open Access Journals (Sweden)

    Andrea Magri

    2015-05-01

    Full Text Available We have studied the electronic properties and the charge carrier mobility of the organic semiconductor tris(1-oxo-1H-phenalen-9-olatealuminium(III (Al(Op3 both experimentally and theoretically. We experimentally estimated the HOMO and LUMO energy levels to be −5.93 and −3.26 eV, respectively, which were close to the corresponding calculated values. Al(Op3 was successfully evaporated onto quartz substrates and was clearly identified in the absorption spectra of both the solution and the thin film. A structured steady state fluorescence emission was detected in solution, whereas a broad, red-shifted emission was observed in the thin film. This indicates the formation of excimers in the solid state, which is crucial for the transport properties. The incorporation of Al(Op3 into organic thin film transistors (TFTs was performed in order to measure the charge carrier mobility. The experimental setup detected no electron mobility, while a hole mobility between 0.6 × 10−6 and 2.1 × 10−6 cm2·V−1·s−1 was measured. Theoretical simulations, on the other hand, predicted an electron mobility of 9.5 × 10−6 cm2·V−1·s−1 and a hole mobility of 1.4 × 10−4 cm2·V−1·s−1. The theoretical simulation for the hole mobility predicted an approximately one order of magnitude higher hole mobility than was observed in the experiment, which is considered to be in good agreement. The result for the electron mobility was, on the other hand, unexpected, as both the calculated electron mobility and chemical common sense (based on the capability of extended aromatic structures to efficiently accept and delocalize additional electrons suggest more robust electron charge transport properties. This discrepancy is explained by the excimer formation, whose inclusion in the multiscale simulation workflow is expected to bring the theoretical simulation and experiment into agreement.

  5. Mobile health platform for pressure ulcer monitoring with electronic health record integration.

    Science.gov (United States)

    Rodrigues, Joel J P C; Pedro, Luís M C C; Vardasca, Tomé; de la Torre-Díez, Isabel; Martins, Henrique M G

    2013-12-01

    Pressure ulcers frequently occur in patients with limited mobility, for example, people with advanced age and patients wearing casts or prostheses. Mobile information communication technologies can help implement ulcer care protocols and the monitoring of patients with high risk, thus preventing or improving these conditions. This article presents a mobile pressure ulcer monitoring platform (mULCER), which helps control a patient's ulcer status during all stages of treatment. Beside its stand-alone version, it can be integrated with electronic health record systems as mULCER synchronizes ulcer data with any electronic health record system using HL7 standards. It serves as a tool to integrate nursing care among hospital departments and institutions. mULCER was experimented with in different mobile devices such as LG Optimus One P500, Samsung Galaxy Tab, HTC Magic, Samsung Galaxy S, and Samsung Galaxy i5700, taking into account the user's experience of different screen sizes and processing characteristics.

  6. Electron and hole drift mobility measurements on methylammonium lead iodide perovskite solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Maynard, Brian; Long, Qi; Schiff, Eric A. [Department of Physics, Syracuse University, Syracuse, New York 13244 (United States); Yang, Mengjin; Zhu, Kai [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Kottokkaran, Ranjith; Abbas, Hisham; Dalal, Vikram L. [Iowa State University, Ames, Iowa 50011 (United States)

    2016-04-25

    We report nanosecond domain time-of-flight measurements of electron and hole photocarriers in methylammonium lead iodide perovskite solar cells. The mobilities ranged from 0.06 to 1.4 cm{sup 2}/Vs at room temperature, but there is little systematic difference between the two carriers. We also find that the drift mobilities are dispersive (time-dependent). The dispersion parameters are in the range of 0.4–0.7, and they imply that terahertz domain mobilities will be much larger than nanosecond domain mobilities. The temperature-dependences of the dispersion parameters are consistent with confinement of electron and hole transport to fractal-like spatial networks within nanoseconds of their photogeneration.

  7. Interoperability of a mobile health care solution with electronic healthcare record systems.

    Science.gov (United States)

    De Toledo, P; Lalinde, W; Del Pozo, F; Thurber, D; Jimenez-Fernandez, S

    2006-01-01

    Mobile health care solutions involving patient monitoring are an increasingly accepted element in chronic disease management strategies. When used in healthcare systems with different providers, it is essential that the information gathered from the patient is available at each of these providers information repositories. This paper describes the design of a connectivity interface based on the HL7 standard that allows the MOTOHEALTH mobile health care solution to communicate with external electronic healthcare record systems supporting HL7.

  8. Mobility and bulk electron-phonon interaction in two-dimensional materials

    DEFF Research Database (Denmark)

    Gunst, Tue; Brandbyge, Mads; Markussen, Troels

    2015-01-01

    We present calculations of the phonon-limited mobility in intrinsic n-type monolayer graphene, silicene and MoS2. The material properties, including the electron-phonon interaction, are calculated from first principles. Unlike graphene, the carriers in silicene show strong interaction with the out......-of-plane modes. However, we find that graphene only has a slightly higher mobility compared to silicene. For MoS2 we obtain several orders of magnitude lower mobilities and in agreement with other recent theoretical results. The simulations illustrate the predictive capabilities of the newly implemented...

  9. A Survey on the Reliability of Power Electronics in Electro-Mobility Applications

    DEFF Research Database (Denmark)

    Gadalla, Brwene Salah Abdelkarim; Schaltz, Erik; Blaabjerg, Frede

    2015-01-01

    Reliability is an important issue in the field of power electronics since most of the electrical energy is today processed by power electronics. In most of the electro-mobility applications, e.g. electric and hybridelectric vehicles, power electronic are commonly used in very harsh environment...... and extending the service lifetime as well. Research within power electronics is of high interest as it has an important impact in the industry of the electro-mobility applications. According to the aforementioned explanations, this paper will provide an overview of the common factors (thermal cycles, power...... cycles, vibrations, voltage stress and current ripple stress) affecting the reliability of power electronics in electromobility applications. Also, the researchers perspective is summarized from 2001 to 2015....

  10. Electron mobility enhancement in metalorganic-vapor-phase-epitaxy-grown InAlN high-electron-mobility transistors by control of surface morphology of spacer layer

    Science.gov (United States)

    Yamada, Atsushi; Ishiguro, Tetsuro; Kotani, Junji; Nakamura, Norikazu

    2018-01-01

    We demonstrated low-sheet-resistance metalorganic-vapor-phase-epitaxy-grown InAlN high-electron-mobility transistors using AlGaN spacers with excellent surface morphology. We systematically investigated the effects of AlGaN spacer growth conditions on surface morphology and electron mobility. We found that the surface morphology of InAlN barriers depends on that of AlGaN spacers. Ga desorption from AlGaN spacers was suppressed by increasing the trimethylaluminum (TMA) supply rate, resulting in the small surface roughnesses of InAlN barriers and AlGaN spacers. Moreover, we found that an increase in the NH3 supply rate also improved the surface morphologies of InAlN barriers and AlGaN spacers as long as the TMA supply rate was high enough to suppress the degradation of GaN channels. Finally, we realized a low sheet resistance of 185.5 Ω/sq with a high electron mobility of 1210 cm2 V‑1 s‑1 by improving the surface morphologies of AlGaN spacers and InAlN barriers.

  11. Strong Electron-Deficient Polymers Lead to High Electron Mobility in Air and Their Morphology-Dependent Transport Behaviors.

    Science.gov (United States)

    Zheng, Yu-Qing; Lei, Ting; Dou, Jin-Hu; Xia, Xin; Wang, Jie-Yu; Liu, Chen-Jiang; Pei, Jian

    2016-09-01

    Planar backbone, locked conformation, and low lowest unoccupied molecular orbital level provide polymer F4 BDOPV-2T with ultrahigh electron mobilities of up to 14.9 cm(2) V(-1) s(-1) and good air stability. It is found that the nonlinear transfer curves can be tuned to near-ideal ones by changing fabrication conditions, indicating that film morphology largely contributes to the nonlinear transfer curves in high-mobility conjugated polymers. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Analysis of proton radiation effects on gallium nitride high electron mobility transistors

    OpenAIRE

    Augustine, Robert T.

    2017-01-01

    Approved for public release; distribution is unlimited In this work, a physics-based simulation of non-ionizing proton radiation damage effects at different energy levels on a GaN-on-silicon high electron mobility transistor was created. Based on physical results of 2.0-MeV protons irradiation to fluence levels of 6 1014 protons cm2, the simulation was tuned to match electron mobility n and then compared to threshold voltage Vth on state resistance Ron and transconductance gm. A Monte Carl...

  13. Electronic data capture platform for clinical research based on mobile phones and near field communication technology.

    Science.gov (United States)

    Morak, Jürgen; Schwetz, Verena; Hayn, Dieter; Fruhwald, Friedrich; Schreier, Gunter

    2008-01-01

    Electronic data capture systems support data acquisition for clinical research and enable the evaluation of new investigational medical devices. In case of evaluating a device the most challenging part is the user interface i.e. the solution how to acquire the data within a clinical setting and to synchronize them with a web-based data centre. The aim of this paper is to describe the development of an electronic data capture system with a mobile data input solution based on mobile phones and Near Field Communication technology. This system was evaluated within a real clinical setting and demonstrated high usability, security and reliability.

  14. Development of mobile electronic health records application in a secondary general hospital in Korea.

    Science.gov (United States)

    Choi, Wookjin; Park, Min Ah; Hong, Eunseok; Kim, Sunhyu; Ahn, Ryeok; Hong, Jungseok; Song, Seungyeol; Kim, Tak; Kim, Jeongkeun; Yeo, Seongwoon

    2013-12-01

    The recent evolution of mobile devices has opened new possibilities of providing strongly integrated mobile services in healthcare. The objective of this paper is to describe the decision driver, development, and implementation of an integrated mobile Electronic Health Record (EHR) application at Ulsan University Hospital. This application helps healthcare providers view patients' medical records and information without a stationary computer workstation. We developed an integrated mobile application prototype that aimed to improve the mobility and usability of healthcare providers during their daily medical activities. The Android and iOS platform was used to create the mobile EHR application. The first working version was completed in 5 months and required 1,080 development hours. The mobile EHR application provides patient vital signs, patient data, text communication, and integrated EHR. The application allows our healthcare providers to know the status of patients within and outside the hospital environment. The application provides a consistent user environment on several compatible Android and iOS devices. A group of 10 beta testers has consistently used and maintained our copy of the application, suggesting user acceptance. We are developing the integrated mobile EHR application with the goals of implementing an environment that is user-friendly, implementing a patient-centered system, and increasing the hospital's competitiveness.

  15. Comparison of Gallium Nitride High Electron Mobility Transistors Modeling in Two and Three Dimensions

    Science.gov (United States)

    2007-12-01

    15. NUMBER OF PAGES 77 14. SUBJECT TERMS Gallium Nitride, HEMT, High Electron Mobility Transistor, Silvaco , ATLAS , modeling. 16. PRICE...Chapter II of this thesis and the Silvaco Atlas Manual from 2007 [21]. The present ATLASTM program incorporates modifications specifically for the...IEEE Trans. Electron Devices, vol. 47, pp. 2031–2036, November 2000. [21] Silvaco International, “ Silvaco International, ATLAS User’s Manual

  16. Electric field dependence of the electron mobility in bulk wurtzite ZnO

    Indian Academy of Sciences (India)

    ZnO) material is studied. The low-field electron mobility is calculated as a function of doping concentration and lattice temperature. The results show that above nearly 50 K the electrical conduction is governed by activation through the bulk ...

  17. Electron heating due to microwave photoexcitation in the high mobility GaAs/AlGaAs two dimensional electron system

    Energy Technology Data Exchange (ETDEWEB)

    Ramanayaka, A. N.; Mani, R. G. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Wegscheider, W. [Laboratorium für Festkörperphysik, ETH Zürich, CH-8093 Zürich (Switzerland)

    2013-12-04

    We extract the electron temperature in the microwave photo-excited high mobility GaAs/AlGaAs two dimensional electron system (2DES) by studying the influence of microwave radiation on the amplitude of Shubnikov-de Haas oscillations (SdHOs) in a regime where the cyclotron frequency, ω{sub c}, and the microwave angular frequency, ω, satisfy 2ω ≤ ω{sub c} ≤ 3.5ω The results indicate that increasing the incident microwave power has a weak effect on the amplitude of the SdHOs and therefore the electron temperature, in comparison to the influence of modest temperature changes on the dark-specimen SdH effect. The results indicate negligible electron heating under modest microwave photo-excitation, in good agreement with theoretical predictions.

  18. 76 FR 40930 - In the Matter of Certain Electronic Devices, Including Mobile Phones, Portable Music Players, and...

    Science.gov (United States)

    2011-07-12

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION In the Matter of Certain Electronic Devices, Including Mobile Phones, Portable Music Players, and... electronic devices, including mobile phones, portable music players, and computers by reason of infringement...

  19. Analysis of Proton Radiation Effects on Gallium Nitride High Electron Mobility Transistors

    Science.gov (United States)

    2017-03-01

    Koschnick, J.-M. Spaeth, B. Beaumont, and P. Gibart, “Proton bombardment-induced electron traps in epitaxially grown n-gan,” Applied physics letters , vol...Density-dependent electron transport and precise modeling of gan high electron mobility transistors,” Applied Physics Letters , vol. 107, no. 15, p. 153504...heterostructure field-effect transistors,” Applied Physics Letters , vol. 98, no. 12, p. 123512, 2011. [30] L. Lv, X. Ma, J. Zhang, Z. Bi, L. Liu, H. Shan

  20. Electron mobility in abrupt-interface and step-graded AlGaN/GaN Heterostructures

    Science.gov (United States)

    Liu, Dongfeng; Lin, Donghua; Li, Zhizhong; Guo, Kangxian

    2017-10-01

    Based on the ensemble Monte Carlo method, we present a comparative study of the electron mobility of two-dimensional electron gases (2DEGs) formed in AlGaN/GaN abrupt-interface heterostructures (ABHs) and step-graded heterostructures (SGHs) at room temperature. We find that the electron mobility in SGHs is obviously higher than that in ABHs. The dependence of electron mobilities on the AlGaN barrier thickness is found to have a close relationship with the dislocation scatterings of electrons. On the other hand, our calculated results show that the mobility difference between SGHs and ABHs generally increases with AlGaN barrier thickness, which means that SGHs with a thicker barrier layer play a more prominent role in obtaining high mobility, compared with ABH counterparts.

  1. DEVELOPING OF ELECTRONIC TEACHING MATERIAL BASED ON MOBILE LEARNING IN THE WAVE SUBJECTS

    Directory of Open Access Journals (Sweden)

    D. H. Rif’ati

    2015-07-01

    Full Text Available In the advanced and modern era, technological sophistication led to learning which initially runs, in which teachers and students meet each other and communicate in the classroom, can be implemented through of information technology. Along with the development of information, where books and teachers who initially as a primary source of learning, are now beginning to experience growth from the internet. Mobile learning defined as mobile devices that are used in the learning process. The wave course is one of subject that must be taken by students of physics education in the third semester. This course emphasizes the concepts of wave were reviewed mathematically and the phenomenon that occurs in everyday life. Mobile learning developed in this study in the form of electronic teaching materials on subjects of waves. The aim of this study was to develop electronic teaching material in the form of mobile learning. The sample of this study is 80 students in the third semester students who are taking waves courses. The results show that mobile learning that has been developed has score 3.8 and included valid criteria. Pada era yang serba maju dan modern, kecanggihan teknologi menyebabkan pembelajaran yang awalnya berjalan satu arah, dimana guru dan siswa saling bertemu dan berkomunikasi di dalam kelas, dapat dilaksanakan melalui bantuan teknologi.informasi. Seiring dengan perkembangan informasi, buku dan guru yang awalnya sebagai sumber belajar utama, saat ini sudah mulai mengalami perkembangan dimana sumber belajar yang berasal dari internet sudah mulai sering dimanfaatkan dalam proses pembelajaran. Mobile larning didefinisikan sebagai perangkat mobile yang dipergunakan dalam proses belajar mengajar. Mata kuliah gelombang sendiri merupakan salah satu mata kuliah yang wajib ditempuh oleh mahasiswa program studi pendidikan fisika semester 3. Mata kuliah ini menekankan pada konsep gelombang yang ditinjau secara matematis dan fenomenanya yang terjadi

  2. High-Electron-Mobility SiGe on Sapphire Substrate for Fast Chipsets

    Directory of Open Access Journals (Sweden)

    Hyun Jung Kim

    2015-01-01

    Full Text Available High-quality strain-relaxed SiGe films with a low twin defect density, high electron mobility, and smooth surface are critical for device fabrication to achieve designed performance. The mobilities of SiGe can be a few times higher than those of silicon due to the content of high carrier mobilities of germanium (p-type Si: 430 cm2/V·s, p-type Ge: 2200 cm2/V·s, n-type Si: 1300 cm2/V·s, and n-type Ge: 3000 cm2/V·s at 1016 per cm3 doping density. Therefore, radio frequency devices which are made with rhombohedral SiGe on c-plane sapphire can potentially run a few times faster than RF devices on SOS wafers. NASA Langley has successfully grown highly ordered single crystal rhombohedral epitaxy using an atomic alignment of the [111] direction of cubic SiGe on top of the [0001] direction of the sapphire basal plane. Several samples of rhombohedrally grown SiGe on c-plane sapphire show high percentage of a single crystalline over 95% to 99.5%. The electron mobilities of the tested samples are between those of single crystals Si and Ge. The measured electron mobility of 95% single crystal SiGe was 1538 cm2/V·s which is between 350 cm2/V·s (Si and 1550 cm2/V·s (Ge at 6 × 1017/cm3 doping concentration.

  3. Electronic waste recovery in Finland: Consumers' perceptions towards recycling and re-use of mobile phones.

    Science.gov (United States)

    Ylä-Mella, Jenni; Keiski, Riitta L; Pongrácz, Eva

    2015-11-01

    This paper examines consumers' awareness and perceptions towards mobile phone recycling and re-use. The results are based on a survey conducted in the city of Oulu, Finland, and analysed in the theoretical framework based on the theories of planned behaviour (TPB) and value-belief-norm (VBN). The findings indicate that consumers' awareness of the importance and existence of waste recovery system is high; however, awareness has not translated to recycling behaviour. The survey reveals that 55% of respondents have two or more unused mobile phones at homes. The more phones stored at homes, the more often reasons 'I don't know where to return' and/or 'have not got to do it yet' were mentioned. This indicates that proximity and the convenience of current waste management system are inadequate in promoting the return of small waste electrical and electronic equipment (WEEE). To facilitate re-use, and the highest level of recovery, consumers will need to be committed to return end-of-use electronics to WEEE collection centres without delays. Further, the supply and demand of refurbished mobile phones do not meet at this moment in Finland due to consumer's storing habits versus expectations of recent features under guarantee and unrealistic low prizes. The study also points out that, in order to change current storing habits of consumers, there is an explicit need for more information and awareness on mobile phone collection in Finland, especially on regarding retailers' take-back. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Integration of a mobile-integrated therapy with electronic health records: lessons learned.

    Science.gov (United States)

    Peeples, Malinda M; Iyer, Anand K; Cohen, Joshua L

    2013-05-01

    Responses to the chronic disease epidemic have predominantly been standardized in their approach to date. Barriers to better health outcomes remain, and effective management requires patient-specific data and disease state knowledge be presented in methods that foster clinical decision-making and patient self-management. Mobile technology provides a new platform for data collection and patient-provider communication. The mobile device represents a personalized platform that is available to the patient on a 24/7 basis. Mobile-integrated therapy (MIT) is the convergence of mobile technology, clinical and behavioral science, and scientifically validated clinical outcomes. In this article, we highlight the lessons learned from functional integration of a Food and Drug Administration-cleared type 2 diabetes MIT into the electronic health record (EHR) of a multiphysician practice within a large, urban, academic medical center. In-depth interviews were conducted with integration stakeholder groups: mobile and EHR software and information technology teams, clinical end users, project managers, and business analysts. Interviews were summarized and categorized into lessons learned using the Architecture for Integrated Mobility® framework. Findings from the diverse stakeholder group of a MIT-EHR integration project indicate that user workflow, software system persistence, environment configuration, device connectivity and security, organizational processes, and data exchange heuristics are key issues that must be addressed. Mobile-integrated therapy that integrates patient self-management data with medical record data provides the opportunity to understand the potential benefits of bidirectional data sharing and reporting that are most valuable in advancing better health and better care in a cost-effective way that is scalable for all chronic diseases. © 2013 Diabetes Technology Society.

  5. Determination of grain boundary mobility during recrystallization by statistical evaluation of electron backscatter diffraction measurements

    Energy Technology Data Exchange (ETDEWEB)

    Basu, I., E-mail: basu@imm.rwth-aachen.de; Chen, M.; Loeck, M.; Al-Samman, T.; Molodov, D.A.

    2016-07-15

    One of the key aspects influencing microstructural design pathways in metallic systems is grain boundary motion. The present work introduces a method by means of which direct measurement of grain boundary mobility vs. misorientation dependence is made possible. The technique utilizes datasets acquired by means of serial electron backscatter diffraction (EBSD) measurements. The experimental EBSD measurements are collectively analyzed, whereby datasets were used to obtain grain boundary mobility and grain aspect ratio with respect to grain boundary misorientation. The proposed method is further validated using cellular automata (CA) simulations. Single crystal aluminium was cold rolled and scratched in order to nucleate random orientations. Subsequent annealing at 300 °C resulted in grains growing, in the direction normal to the scratch, into a single deformed orientation. Growth selection was observed, wherein the boundaries with misorientations close to Σ7 CSL orientation relationship (38° 〈111〉) migrated considerably faster. The obtained boundary mobility distribution exhibited a non-monotonic behavior with a maximum corresponding to misorientation of 38° ± 2° about 〈111〉 axes ± 4°, which was 10–100 times higher than the mobility values of random high angle boundaries. Correlation with the grain aspect ratio values indicated a strong growth anisotropy displayed by the fast growing grains. The observations have been discussed in terms of the influence of grain boundary character on grain boundary motion during recrystallization. - Highlights: • Statistical microstructure method to measure grain boundary mobility during recrystallization • Method implementation independent of material or crystal structure • Mobility of the Σ7 boundaries in 5N Al was calculated as 4.7 × 10{sup –8} m{sup 4}/J ⋅ s. • Pronounced growth selection in the recrystallizing nuclei in Al • Boundary mobility values during recrystallization 2–3 orders of

  6. Social influence model and electronic word of mouth: PC versus mobile internet

    OpenAIRE

    Okazaki, Shintaro

    2009-01-01

    Compared with laptop or desktop computers, mobile devices offer greater flexibility in time and space, thus enabling consumers to be connected online more continually. In addition, their small size, portability and ease of use with location-based capabilities facilitate sending and receiving timely information in the right place. Drawing upon a social influence model proposed by Dholakia et al. (2004), this paper proposes a causal model for consumer participation in electronic ...

  7. Interaction-induced huge magnetoresistance in a high mobility two-dimensional electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Bockhorn, L.; Haug, R. J. [Institut für Festkörperphysik, Leibniz Universität Hannover, D-30167 Hannover (Germany); Gornyi, I. V. [Institut für Nanotechnologie, Karlsruher Institut of Technology, D-76021 Karlsruhe (Germany); Schuh, D. [Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93053 Regensburg (Germany); Wegscheider, W. [ETH Zürich (Switzerland)

    2013-12-04

    A strong negative magnetoresistance is observed in a high-mobility two-dimensional electron gas in a GaAs/Al{sub 0.3}Ga{sub 0.7}As quantum well. We discuss that the negative magnetoresistance consists of a small peak induced by a combination of two types of disorder and a huge magnetoresistance explained by the interaction correction to the conductivity for mixed disorder.

  8. Extraction of terahertz emission from a grating-coupled high-electron-mobility transistor

    Institute of Scientific and Technical Information of China (English)

    Zhou Yu; Li Xinxing; Tan Renbing; Xue Wei; Huang Yongdan; Lou Shitao; Zhang Baoshun; Qin Hua

    2013-01-01

    In a grating-coupled high-electron-mobility transistor,weak terahertz emission with wavelength around 400μm was observed by using a Fourier-transform spectrometer.The absolute terahertz emission power was extracted from a strong background blackbody emission by using a modulation technique.The power of terahertz emission is proportional to the drain-source current,while the power of blackbody emission has a distinct relation with the electrical power.The dependence on the drain-source bias and the gate voltage suggests that the terahertz emission is induced by accelerated electrons interacting with the grating.

  9. Mobilities

    DEFF Research Database (Denmark)

    to social networks, personal identities, and our relationship to the built environment. The omnipresence of mobilities within everyday life, high politics, technology, and tourism (to mention but a few) all point to a key insight harnessed by the ‘mobilities turn’. Namely that mobilities is much more than...... and environmental degradation. The spaces and territories marked by mobilities as well as the sites marked by the bypassing of such are explored. Moreover, the architectural and technological dimensions to infrastructures and sites of mobilities will be included as well as the issues of power, social exclusion......, consumption, surveillance and mobilities history to mention some of the many themes covered by this reference work. This new title will focus on the academic contributions to this understanding by primarily focusing on works and publications in the aftermath of the seminal book and landmark text ‘Sociology...

  10. AlGaN/GaN high electron mobility transistors grown on 3C-SiC/Si(1 1 1)

    Science.gov (United States)

    Cordier, Yvon; Portail, Marc; Chenot, Sébastien; Tottereau, Olivier; Zielinski, Marcin; Chassagne, Thierry

    2008-10-01

    The elaboration of Gallium nitride (GaN)-based high electron mobility transistors (HEMTs) structures is comparatively investigated on cubic SiC/Si(1 1 1) templates and on silicon substrates. As compared with silicon, 3C-SiC/Si(1 1 1) template is less sensitive to the detrimental nitridation effect of ammonia, and it allows a reduction of the stress in GaN films due to both lower lattice and thermal expansion coefficient mismatch. Crack-free GaN layers and AlGaN/GaN HEMTs with total thicknesses exceeding 2 μm were successfully grown by molecular beam epitaxy on optimized 0.8-μm-thick 3C-SiC/Si templates elaborated by chemical vapor deposition. A threading dislocation density below 5×10 9 cm -2 and a two-dimensional electron gas with a sheet carrier concentration of 1.1×10 13 cm -2 and an electron mobility of 2050 cm 2/V s at room temperature have been obtained. The feasibility of the 3C-SiC/Si(1 1 1) approach is demonstrated by the structural and electrical quality of these structures, as well as the characteristics of transistors that are at least equivalent to reference transistors realized on bulk silicon substrates.

  11. Large yield production of high mobility freely suspended graphene electronic devices on a polydimethylglutarimide based organic polymer

    NARCIS (Netherlands)

    Tombros, Nikolaos; Veligura, Alina; Junesch, Juliane; Berg, J. Jasper van den; Zomer, Paul J.; Wojtaszek, Magdalena; Vera Marun, Ivan J.; Jonkman, Harry T.; Wees, Bart J. van

    2011-01-01

    The recent observation of a fractional quantum Hall effect in high mobility suspended graphene devices introduced a new direction in graphene physics, the field of electron–electron interaction dynamics. However, the technique used currently for the fabrication of such high mobility devices has

  12. M&E-NetPay: A Micropayment System for Mobile and Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Xiaodi Huang

    2016-08-01

    Full Text Available As an increasing number of people purchase goods and services online, micropayment systems are becoming particularly important for mobile and electronic commerce. We have designed and developed such a system called M&E-NetPay (Mobile and Electronic NetPay. With open interoperability and mobility, M&E-NetPay uses web services to connect brokers and vendors, providing secure, flexible and reliable credit services over the Internet. In particular, M&E-NetPay makes use of a secure, inexpensive and debit-based off-line protocol that allows vendors to interact only with customers, after validating coins. The design of the architecture and protocol of M&E-NetPay are presented, together with the implementation of its prototype in ringtone and wallpaper sites. To validate our system, we have conducted its evaluations on performance, usability and heuristics. Furthermore, we compare our system to the CORBA-based (Common Object Request Broker Architecture off-line micro-payment systems. The results have demonstrated that M&E-NetPay outperforms the .NET-based M&E-NetPay system in terms of performance and user satisfaction.

  13. User evaluation of two electronic mobility aids for persons who are visually impaired: a quasi-experimental study using a standardized mobility course.

    Science.gov (United States)

    Roentgen, Uta R; Gelderblom, Gert Jan; de Witte, Luc P

    2012-01-01

    This study was conducted to enhance insight into the functionality, usability, and efficacy of two systematically selected Electronic Mobility Aids (EMA) aimed at obstacle detection and orientation. Eight persons who are visually impaired participated in a user evaluation of the UltraCane and the Miniguide. The participants' mobility performance was observed while completing a standardized indoor mobility course with their regular mobility aid, then with each EMA, and assessed in terms of speed, Percentage Preferred Walking Speed (PPWS), type and number of mobility incidents made. Interviews were administered to ascertain users' satisfaction with the functionality, effectiveness and specific features of the assistive devices. Walking speed and PPWS declined when using an EMA compared to the long cane. The mean total number of previously defined mobility incidents decreased significantly and also the type of mobility incidents changed. Generally, participants were quite satisfied with the use of the EMA, and detailed advantageous as well as disadvantageous aspects concerning functionality and certain features of both devices. The UltraCane and the Miniguide have proven to be effective on an indoor mobility course. Individual users' characteristics and preferences appear to be critical for their appraisal of the devices.

  14. Training a Network of Electronic Neurons for Control of a Mobile Robot

    Science.gov (United States)

    Vromen, T. G. M.; Steur, E.; Nijmeijer, H.

    An adaptive training procedure is developed for a network of electronic neurons, which controls a mobile robot driving around in an unknown environment while avoiding obstacles. The neuronal network controls the angular velocity of the wheels of the robot based on the sensor readings. The nodes in the neuronal network controller are clusters of neurons rather than single neurons. The adaptive training procedure ensures that the input-output behavior of the clusters is identical, even though the constituting neurons are nonidentical and have, in isolation, nonidentical responses to the same input. In particular, we let the neurons interact via a diffusive coupling, and the proposed training procedure modifies the diffusion interaction weights such that the neurons behave synchronously with a predefined response. The working principle of the training procedure is experimentally validated and results of an experiment with a mobile robot that is completely autonomously driving in an unknown environment with obstacles are presented.

  15. [Design and Implementation of a Mobile Operating Room Information Management System Based on Electronic Medical Record].

    Science.gov (United States)

    Liu, Baozhen; Liu, Zhiguo; Wang, Xianwen

    2015-06-01

    A mobile operating room information management system with electronic medical record (EMR) is designed to improve work efficiency and to enhance the patient information sharing. In the operating room, this system acquires the information from various medical devices through the Client/Server (C/S) pattern, and automatically generates XML-based EMR. Outside the operating room, this system provides information access service by using the Browser/Server (B/S) pattern. Software test shows that this system can correctly collect medical information from equipment and clearly display the real-time waveform. By achieving surgery records with higher quality and sharing the information among mobile medical units, this system can effectively reduce doctors' workload and promote the information construction of the field hospital.

  16. Electronic characteristics of p-type transparent SnO monolayer with high carrier mobility

    Energy Technology Data Exchange (ETDEWEB)

    Du, Juan [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Xia, Congxin, E-mail: xiacongxin@htu.edu.cn [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Liu, Yaming [Henan Institute of Science and Technology, Xinxiang 453003 (China); Li, Xueping [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China); Peng, Yuting [Department of Physics, University of Texas at Arlington, TX 76019 (United States); Wei, Shuyi [College of Physics and Materials Science, Henan Normal University, Xinxiang, Henan 453007 (China)

    2017-04-15

    Graphical abstract: SnO monolayer is a p-type transparent semiconducting oxide with high hole mobility (∼641 cm{sup 2} V{sup −1} s{sup −1}), which is much higher than that of MoS{sub 2} monolayer, which indicate that it can be a promising candidate for high-performance nanoelectronic devices. Display Omitted - Highlights: • SnO monolayer is a p-type transparent semiconducting oxide. • The transparent properties can be still maintained under the strain 8%. • It has a high hole mobility (∼641 cm{sup 2} V{sup −1} s{sup −1}), which is higher than that of MoS{sub 2} monolayer. - Abstract: More recently, two-dimensional (2D) SnO nanosheets are attaching great attention due to its excellent carrier mobility and transparent characteristics. Here, the stability, electronic structures and carrier mobility of SnO monolayer are investigated by using first-principles calculations. The calculations of the phonon dispersion spectra indicate that SnO monolayer is dynamically stable. Moreover, the band gap values are decreased from 3.93 eV to 2.75 eV when the tensile strain is applied from 0% to 12%. Interestingly, SnO monolayer is a p-type transparent semiconducting oxide with hole mobility of 641 cm{sup 2} V{sup −1} s{sup −1}, which is much higher than that of MoS{sub 2} monolayer. These findings make SnO monolayer becomes a promising 2D material for applications in nanoelectronic devices.

  17. A Fortran program for calculating electron or hole mobility in disordered semiconductors from first-principles

    Science.gov (United States)

    Li, Zi; Zhang, Xu; Lu, Gang

    2011-12-01

    A Fortran program is developed to calculate charge carrier (electron or hole) mobility in disordered semiconductors from first-principles. The method is based on non-adiabatic ab initio molecular dynamics and static master equation, treating dynamic and static disorder on the same footing. We have applied the method to calculate the hole mobility in disordered poly(3-hexylthiophene) conjugated polymers as a function of temperature and electric field and obtained excellent agreements with experimental results. The program could be used to explore structure-mobility relation in disordered semiconducting polymers/organic semiconductors and aid rational design of these materials. Program summaryProgram title: FPMu Catalogue identifier: AEJV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJV_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.: 788 580 No. of bytes in distributed program, including test data, etc.: 8 433 024 Distribution format: tar.gz Programming language: Fortran 90 Computer: Any architecture with a Fortran 90 compiler Operating system: Linux, Windows RAM: Proportional to the system size, in our example, 1.2 GB Classification: 7.9 Nature of problem: Determine carrier mobility from first-principles in disordered semiconductors as a function of temperature, electric field and carrier concentration. Solution method: Iteratively solve master equation with carrier state energy and transition rates determined from first-principles. Restrictions: Mobility for disordered semiconductors where the carrier wave-functions are localized and the carrier transport is due to phonon-assisted hopping mechanism. Running time: Depending on the system size (about an hour for the example here).

  18. Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Mikheev, Evgeny; Himmetoglu, Burak; Kajdos, Adam P.; Moetakef, Pouya; Cain, Tyler A.; Van de Walle, Chris G.; Stemmer, Susanne [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2015-02-09

    We analyze and compare the temperature dependence of the electron mobility of two- and three-dimensional electron liquids in SrTiO{sub 3}. The contributions of electron-electron scattering must be taken into account to accurately describe the mobility in both cases. For uniformly doped, three-dimensional electron liquids, the room temperature mobility crosses over from longitudinal optical (LO) phonon-scattering-limited to electron-electron-scattering-limited as a function of carrier density. In high-density, two-dimensional electron liquids, LO phonon scattering is completely screened and the mobility is dominated by electron-electron scattering up to room temperature. The possible origins of the observed behavior and the consequences for approaches to improve the mobility are discussed.

  19. TD-DFT study on electron transfer mobility and intramolecular hydrogen bond of substituted indigo derivatives

    Science.gov (United States)

    Ma, Chi; Li, Hui; Yang, Yonggang; Li, Donglin; Liu, Yufang

    2015-10-01

    The density functional theory (DFT) and time-dependent density functional theory (TDDFT) method were carried out to investigate the ground and excited states of indigo and its derivative molecules. The results demonstrate that the intramolecular hydrogen bond I is weakened and the intramolecular hydrogen bond II is strengthened upon photo-excitation to the S1 state. In the absorption spectra, the substitution at R4R4, of indigo causes a significant redshift. In addition, the halogen substitution obviously increases the electron transfer mobility of indigo. It is proved that the halogen substitution may be a new method to design high performance organic semiconductors.

  20. Cryogenic, low-noise high electron mobility transistor amplifiers for the Deep Space Network

    Science.gov (United States)

    Bautista, J. J.

    1993-01-01

    The rapid advances recently achieved by cryogenically cooled high electron mobility transistor (HEMT) low-noise amplifiers (LNA's) in the 1- to 10-GHz range are making them extremely competitive with maser amplifiers. In order to address future spacecraft navigation, telemetry, radar, and radio science needs, the Deep Space Network is investing both maser and HEMT amplifiers for its Ka-band (32-GHz) downlink capability. This article describes the current state cryogenic HEMT LNA development at Ka-band for the DSN. Noise performance results at S-band (2.3 GHz) and X-band (8.5 GHz) for HEMT's and masers are included for completeness.

  1. GaAs Device Reliability: High Electron Mobility Transistors and Heterojunction Bipolar Transistors

    Science.gov (United States)

    Ren, F.; Douglas, E. A.; Pearton, Stephen J.

    The two main GaAs-based electronic device technologies are high electron mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs). Both technologies are commercialized for use in low-noise amplifiers, radar, and fiber optic data transmission systems. In this chapter, we will summarize the degradation mechanisms that limit the lifetime of these devices. A variety of contact and surface degradation mechanisms have been reported but differ in the two device technologies - for HEMTs, the layers are thin and relatively lightly doped compared to HBT structures, and there is a metal Schottky gate that is directly on the semiconductor. By contrast, the HBT relies on pn junctions for current modulation and has only ohmic contacts. This leads to different degradation mechanisms for the two types of devices.

  2. Collaborative Research Centre 694 “Integration of electronic components into mobile systems”-Motivation and survey

    Science.gov (United States)

    Weckenmann, Albert; Schmidt, Lorenz-Peter; Bookjans, Martin

    Within the collaborative research centre 694 'Integration of electronic components into mobile systems' intelligent mechatronic systems are explored for application at the place of action. Especially in the automotive sector highest requirements on system safety are combined with an enormous importance of the production for the whole national economy. Therefore the collaborative research centre is led by the vision to integrate electronic components in sensors and actors of mobile systems. About 30 scientists at nine participating academic and non-academic institutions in Erlangen explore mechatronic solutions for the requirements on manufacturing processes, electronic systems and quality management techniques within the car of the future.

  3. Calculation and analysis of the mobility and diffusion coefficient of thermal electrons in methane/air premixed flames

    KAUST Repository

    Bisetti, Fabrizio

    2012-12-01

    Simulations of ion and electron transport in flames routinely adopt plasma fluid models, which require transport coefficients to compute the mass flux of charged species. In this work, the mobility and diffusion coefficient of thermal electrons in atmospheric premixed methane/air flames are calculated and analyzed. The electron mobility is highest in the unburnt region, decreasing more than threefold across the flame due to mixture composition effects related to the presence of water vapor. Mobility is found to be largely independent of equivalence ratio and approximately equal to 0.4m 2V -1s -1 in the reaction zone and burnt region. The methodology and results presented enable accurate and computationally inexpensive calculations of transport properties of thermal electrons for use in numerical simulations of charged species transport in flames. © 2012 The Combustion Institute.

  4. Recovery of critical and value metals from mobile electronics enabled by electrochemical processing

    Energy Technology Data Exchange (ETDEWEB)

    Tedd E. Lister; Peiming Wang; Andre Anderko

    2014-10-01

    Electrochemistry-based schemes were investigated as a means to recover critical and value metals from scrap mobile electronics. Mobile electronics offer a growing feedstock for replenishing value and critical metals and reducing need to exhaust primary sources. The electrorecycling process generates oxidizing agents at an anode to dissolve metals from the scrap matrix while reducing dissolved metals at the cathode. The process uses a single cell to maximize energy efficiency. E vs pH diagrams and metals dissolution experiments were used to assess effectiveness of various solution chemistries. Following this work, a flow chart was developed where two stages of electrorecycling were proposed: 1) initial dissolution of Cu, Sn, Ag and magnet materials using Fe+3 generated in acidic sulfate and 2) final dissolution of Pd and Au using Cl2 generated in an HCl solution. Experiments were performed using a simulated metal mixture equivalent to 5 cell phones. Both Cu and Ag were recovered at ~ 97% using Fe+3 while leaving Au and Pd intact. Strategy for extraction of rare earth elements (REE) from dissolved streams is discussed as well as future directions in process development.

  5. Data mining technique for a secure electronic payment transaction using MJk-RSA in mobile computing

    Science.gov (United States)

    G. V., Ramesh Babu; Narayana, G.; Sulaiman, A.; Padmavathamma, M.

    2012-04-01

    Due to the evolution of the Electronic Learning (E-Learning), one can easily get desired information on computer or mobile system connected through Internet. Currently E-Learning materials are easily accessible on the desktop computer system, but in future, most of the information shall also be available on small digital devices like Mobile, PDA, etc. Most of the E-Learning materials are paid and customer has to pay entire amount through credit/debit card system. Therefore, it is very important to study about the security of the credit/debit card numbers. The present paper is an attempt in this direction and a security technique is presented to secure the credit/debit card numbers supplied over the Internet to access the E-Learning materials or any kind of purchase through Internet. A well known method i.e. Data Cube Technique is used to design the security model of the credit/debit card system. The major objective of this paper is to design a practical electronic payment protocol which is the safest and most secured mode of transaction. This technique may reduce fake transactions which are above 20% at the global level.

  6. Electronic Patient Reported Outcomes in Paediatric Oncology - Applying Mobile and Near Field Communication Technology.

    Science.gov (United States)

    Duregger, Katharina; Hayn, Dieter; Nitzlnader, Michael; Kropf, Martin; Falgenhauer, Markus; Ladenstein, Ruth; Schreier, Günter

    2016-01-01

    Electronic Patient Reported Outcomes (ePRO) gathered using telemonitoring solutions might be a valuable source of information in rare cancer research. The objective of this paper was to develop a concept and implement a prototype for introducing ePRO into the existing neuroblastoma research network by applying Near Field Communication and mobile technology. For physicians, an application was developed for registering patients within the research network and providing patients with an ID card and a PIN for authentication when transmitting telemonitoring data to the Electronic Data Capture system OpenClinica. For patients, a previously developed telemonitoring system was extended by a Simple Object Access Protocol (SOAP) interface for transmitting nine different health parameters and toxicities. The concept was fully implemented on the front-end side. The developed application for physicians was prototypically implemented and the mobile application of the telemonitoring system was successfully connected to OpenClinica. Future work will focus on the implementation of the back-end features.

  7. Optical phonon scattering on electronic mobility in Al2O3/AlGaN/AlN/GaN heterostructures

    Science.gov (United States)

    Zhou, X. J.; Qu, Y.; Ban, S. L.; Wang, Z. P.

    2017-12-01

    Considering the built-in electric fields and the two-mode property of transverse optical phonons in AlGaN material, the electronic eigen-energies and wave functions are obtained by solving Schrödinger equation with the finite difference method. The dispersion relations and potentials of the optical phonons are given by the transfer matrix method. The mobility of the two dimensional electron gas influenced by the optical phonons in Al2O3/AlGaN/AlN/GaN heterostructures is investigated based on the theory of Lei-Ting force balance equation. It is found that the scattering from the half-space phonons is the main factor affecting the electronic mobility, and the influence of the other phonons can be ignored. The results show that the mobility decreases with increasing the thicknesses of Al2O3 and AlN layers, but there is no definite relationship between the mobility and the thickness of AlGaN barrier. The mobility is obviously reduced by increasing Al component in AlGaN crystal to show that the effect of ternary mixed crystals is important. It is also found that the mobility increases first and then decreases as the increment of the fixed charges, but decreases always with increasing temperature. The heterostructures constructed here can be good candidates as metal-oxide-semiconductor high-electron-mobility-transistors since they have higher electronic mobility due to the influence from interface phonons weakened by the AlN interlayer.

  8. Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution

    KAUST Repository

    Faber, Hendrik

    2017-04-28

    Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

  9. Heterojunction oxide thin-film transistors with unprecedented electron mobility grown from solution.

    Science.gov (United States)

    Faber, Hendrik; Das, Satyajit; Lin, Yen-Hung; Pliatsikas, Nikos; Zhao, Kui; Kehagias, Thomas; Dimitrakopulos, George; Amassian, Aram; Patsalas, Panos A; Anthopoulos, Thomas D

    2017-03-01

    Thin-film transistors made of solution-processed metal oxide semiconductors hold great promise for application in the emerging sector of large-area electronics. However, further advancement of the technology is hindered by limitations associated with the extrinsic electron transport properties of the often defect-prone oxides. We overcome this limitation by replacing the single-layer semiconductor channel with a low-dimensional, solution-grown In2O3/ZnO heterojunction. We find that In2O3/ZnO transistors exhibit band-like electron transport, with mobility values significantly higher than single-layer In2O3 and ZnO devices by a factor of 2 to 100. This marked improvement is shown to originate from the presence of free electrons confined on the plane of the atomically sharp heterointerface induced by the large conduction band offset between In2O3 and ZnO. Our finding underscores engineering of solution-grown metal oxide heterointerfaces as an alternative strategy to thin-film transistor development and has the potential for widespread technological applications.

  10. A method to determine electron mobility of the two-dimensional electron gas in AlGaN/GaN heterostructure field-effect transistors

    Science.gov (United States)

    Cui, Peng; Lin, Zhaojun; Fu, Chen; Liu, Yan; Lv, Yuanjie

    2017-10-01

    Taking into consideration the resistance variation in the free-contact area versus the gate bias, an applicable method to determine the electron mobility in AlGaN/GaN heterostructure field-effect transistors was presented. Based on the measured capacitance-voltage and current-voltage curves, the new method employed iteration calculation with different scattering mechanisms. Compared to the electron mobility calculated by the traditional method, the electron mobility calculated by the new method shows an apparent difference, especially for the device with a larger gate length. This difference originates from the device with a larger gate length that has a stronger polarization Coulomb field scattering. At last, the correctness and necessity of this method was demonstrated by the comparison between the experimental and calculated transconductance values.

  11. Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2.

    Science.gov (United States)

    Ji, Liping; Shi, Juan; Zhang, Z Y; Wang, Jun; Zhang, Jiachi; Tao, Chunlan; Cao, Haining

    2018-01-07

    Two-dimensional (2D) MoS2 has been considered to be one of the most promising semiconducting materials with the potential to be used in novel nanoelectronic devices. High carrier mobility in the semiconductor is necessary to guarantee a low power dissipation and a high switch speed of the corresponding electronic device. Strain engineering in 2D materials acts as an important approach to tailor and design their electronic and carrier transport properties. In this work, strain is introduced to MoS2 through perpendicularly building van der Waals heterostructures MoSe2-MoS2. Our first-principles calculations demonstrate that acoustic-phonon-limited electron mobility can be significantly enhanced in the heterostructures compared with that in pure multilayer MoS2. It is found that the effective electron mass and the deformation potential constant are relatively smaller in the heterostructures, which is responsible for the enhancement in the electron mobility. Overall, the electron mobility in the heterostructures is about 1.5 times or more of that in pure multilayer MoS2 with the same number of layers for the studied structures. These results indicate that MoSe2 is an excellent material to be heterostructured with multilayer MoS2 to improve the charge transport property.

  12. Adoption and use of electronic health records and mobile technology by home health and hospice care agencies.

    Science.gov (United States)

    Bercovitz, Anita R; Park-Lee, Eunice; Jamoom, Eric

    2013-05-20

    This report presents national estimates on the adoption and use of electronic health records and mobile technology by home health and hospice care agencies, as well as the agency characteristics associated with adoption. Estimates are based on data from the 2007 National Home and Hospice Care Survey, conducted by the Centers for Disease Control and Prevention's National Center for Health Statistics. In 2007, 28% of home health and hospice care agencies adopted both electronic health records and mobile technology, while slightly over half (54%) adopted neither. Sixteen percent of agencies adopted only electronic health records. Adoption of both technologies was associated with number of patients served and agency type. Agencies that were for-profit or were jointly owned with a hospital were more likely to have adopted neither technology. Among agencies with electronic health records, the most commonly used functionalities were patient demographics and clinical notes. Among agencies with mobile technology, functionalities for the Outcome and Assessment Information Set (OASIS), e-mail, and appointment scheduling were the most commonly used. Similar percentages of agencies with electronic health records or mobile technology used clinical decision support systems, computerized physician order entry, electronic reminders for tests, and viewing of test results.

  13. Dosimetric characteristics of electron beams produced by a mobile accelerator for IORT

    Energy Technology Data Exchange (ETDEWEB)

    Pimpinella, M [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA Centro Ricerche Casaccia, c.p. 2400 Rome (Italy); Mihailescu, D [Faculty of Physics, University Al I Cuza, Iasi (Romania); Guerra, A S [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA Centro Ricerche Casaccia, c.p. 2400 Rome (Italy); Laitano, R F [Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti, ENEA Centro Ricerche Casaccia, c.p. 2400 Rome (Italy)

    2007-10-21

    Energy and angular distributions of electron beams with different energies were simulated by Monte Carlo calculations. These beams were generated by the NOVAC7 (registered) system (Hitesys, Italy), a mobile electron accelerator specifically dedicated to intra-operative radiation therapy (IORT). The electron beam simulations were verified by comparing the measured dose distributions with the corresponding calculated distributions. As expected, a considerable difference was observed in the energy and angular distributions between the IORT beams studied in the present work and the electron beams produced by conventional accelerators for non-IORT applications. It was also found that significant differences exist between the IORT beams used in this work and other IORT beams with different collimation systems. For example, the contribution from the scattered electrons to the total dose was found to be up to 15% higher in the NOVAC7 (registered) beams. The water-to-air stopping power ratios of the IORT beams used in this work were calculated on the basis of the beam energy distributions obtained by the Monte Carlo simulations. These calculated stopping power ratios, s{sub w,air}, were compared with the corresponding s{sub w,air} values recommended by the TRS-381 and TRS-398 IAEA dosimetry protocols in order to estimate the deviations between a dosimetry based on generic parameters and a dosimetry based on parameters specifically obtained for the actual IORT beams. The deviations in the s{sub w,air} values were found to be as large as up to about 1%. Therefore, we recommend that a preliminary analysis should always be made when dealing with IORT beams in order to assess to what extent the possible differences in the s{sub w,air} values have to be accounted for or may be neglected on the basis of the specific accuracy needed in clinical dosimetry.

  14. Electron mobility limited by optical phonons in wurtzite InGaN/GaN core-shell nanowires

    Science.gov (United States)

    Liu, W. H.; Qu, Y.; Ban, S. L.

    2017-09-01

    Based on the force-balance and energy-balance equations, the optical phonon-limited electron mobility in InxGa1-xN/GaN core-shell nanowires (CSNWs) is discussed. It is found that the electrons tend to distribute in the core of the CSNWs due to the strong quantum confinement. Thus, the scattering from first kind of the quasi-confined optical (CO) phonons is more important than that from the interface (IF) and propagating (PR) optical phonons. Ternary mixed crystal and size effects on the electron mobility are also investigated. The results show that the PR phonons exist while the IF phonons disappear when the indium composition x line electron density. Our theoretical results are expected to be helpful to develop electronic devices based on CSNWs.

  15. Key-Insulated Undetachable Digital Signature Scheme and Solution for Secure Mobile Agents in Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Yang Shi

    2016-01-01

    Full Text Available Considering the security of both the customers’ hosts and the eShops’ servers, we introduce the idea of a key-insulated undetachable digital signature, enabling mobile agents to generate undetachable digital signatures on remote hosts with the key-insulated property of the original signer’s signing key. From the theoretical perspective, we provide the formal definition and security notion of a key-insulated undetachable digital signature. From the practical perspective, we propose a concrete scheme to secure mobile agents in electronic commerce. The scheme is mainly focused on protecting the signing key from leakage and preventing the misuse of the signature algorithm on malicious servers. Agents do not carry the signing key when they generate digital signatures on behalf of the original signer, so the key is protected on remote servers. Furthermore, if a hacker gains the signing key of the original signer, the hacker is still unable to forge a signature for any time period other than the key being accessed. In addition, the encrypted function is combined with the original signer’s requirement to prevent the misuse of signing algorithm. The scheme is constructed on gap Diffie–Hellman groups with provable security, and the performance testing indicates that the scheme is efficient.

  16. Design, development, and clinical evaluation of the electronic mobility cane for vision rehabilitation.

    Science.gov (United States)

    Bhatlawande, Shripad; Mahadevappa, Manjunatha; Mukherjee, Jayanta; Biswas, Mukul; Das, Debabrata; Gupta, Somedeb

    2014-11-01

    This paper proposes a new electronic mobility cane (EMC) for providing obstacle detection and way-finding assistance to the visually impaired people. The main feature of this cane is that it constructs the logical map of the surrounding environment to deduce the priority information. It provides a simplified representation of the surrounding environment without causing any information overload. It conveys this priority information to the subject by using intuitive vibration, audio or voice feedback. The other novel features of the EMC are staircase detection and nonformal distance scaling scheme. It also provides information about the floor status. It consists of a low power embedded system with ultrasonic sensors and safety indicators. The EMC was subjected to series of clinical evaluations in order to verify its design and to assess its ability to assist the subjects in their daily-life mobility. Clinical evaluations were performed with 16 totally blind and four low vision subjects. All subjects walked controlled and the real-world test environments with the EMC and the traditional white cane. The evaluation results and significant scores of subjective measurements have shown the usefulness of the EMC in vision rehabilitation services.

  17. Phonon-Electron Scattering Limits Free Charge Mobility in Methylammonium Lead Iodide Perovskites.

    Science.gov (United States)

    Karakus, Melike; Jensen, Søren A; D'Angelo, Francesco; Turchinovich, Dmitry; Bonn, Mischa; Cánovas, Enrique

    2015-12-17

    The nature of the photoconductivity in solution-processed films of methylammonium lead iodide perovskite is investigated by determining the variation of the photoconductive response with temperature. Ultrabroadband terahertz (THz) photoconductivity spectra in the 0.3-10 THz range can be reproduced well by a simple Drude-like response at room temperature, where free charge carrier motion is characterized by an average scattering time. The scattering time determined from Drude fits in the 0.3-2THz region increases from ∼4 fs at 300 K (tetragonal phase; mobility of ∼27 cm(2) V(-1) s(-1)) to almost ∼25 fs at 77 K (orthorhombic phase, mobility of ∼150 cm(2) V(-1) s(-1)). For the tetragonal phase (temperature range 150 < T < 300 K) the scattering time shows a ∼T(-3/2) dependence, approaching the theoretical limit for pure acoustic phonon (deformation potential) scattering. Hence, electron-phonon, rather than impurity scattering, sets the upper limit on free charge transport for this perovskite.

  18. A New XOR Structure Based on Resonant-Tunneling High Electron Mobility Transistor

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Sharifi

    2009-01-01

    Full Text Available A new structure for an exclusive-OR (XOR gate based on the resonant-tunneling high electron mobility transistor (RTHEMT is introduced which comprises only an RTHEMT and two FETs. Calculations are done by utilizing a new subcircuit model for simulating the RTHEMT in the SPICE simulator. Details of the design, input, and output values and margins, delay of each transition, maximum operating frequency, static and dynamic power dissipations of the new structure are discussed and calculated and the performance is compared with other XOR gates which confirm that the presented structure has a high performance. Furthermore, to the best of authors' knowledge, it has the least component count in comparison to the existing structures.

  19. AlGaN/GaN High Electron Mobility Transistors with Multi-MgxNy/GaN Buffer

    Directory of Open Access Journals (Sweden)

    P. C. Chang

    2014-01-01

    Full Text Available We report the fabrication of AlGaN/GaN high electron mobility transistors with multi-MgxNy/GaN buffer. Compared with conventional HEMT devices with a low-temperature GaN buffer, smaller gate and source-drain leakage current could be achieved with this new buffer design. Consequently, the electron mobility was larger for the proposed device due to the reduction of defect density and the corresponding improvement of crystalline quality as result of using the multi-MgxNy/GaN buffer.

  20. The Impacts of Attitudes and Engagement on Electronic Word of Mouth (eWOM of Mobile Sensor Computing Applications

    Directory of Open Access Journals (Sweden)

    Yu Zhao

    2016-03-01

    Full Text Available As one of the latest revolutions in networking technology, social networks allow users to keep connected and exchange information. Driven by the rapid wireless technology development and diffusion of mobile devices, social networks experienced a tremendous change based on mobile sensor computing. More and more mobile sensor network applications have appeared with the emergence of a huge amount of users. Therefore, an in-depth discussion on the human–computer interaction (HCI issues of mobile sensor computing is required. The target of this study is to extend the discussions on HCI by examining the relationships of users’ compound attitudes (i.e., affective attitudes, cognitive attitude, engagement and electronic word of mouth (eWOM behaviors in the context of mobile sensor computing. A conceptual model is developed, based on which, 313 valid questionnaires are collected. The research discusses the level of impact on the eWOM of mobile sensor computing by considering user-technology issues, including the compound attitude and engagement, which can bring valuable discussions on the HCI of mobile sensor computing in further study. Besides, we find that user engagement plays a mediating role between the user’s compound attitudes and eWOM. The research result can also help the mobile sensor computing industry to develop effective strategies and build strong consumer user—product (brand relationships.

  1. The Impacts of Attitudes and Engagement on Electronic Word of Mouth (eWOM) of Mobile Sensor Computing Applications.

    Science.gov (United States)

    Zhao, Yu; Liu, Yide; Lai, Ivan K W; Zhang, Hongfeng; Zhang, Yi

    2016-03-18

    As one of the latest revolutions in networking technology, social networks allow users to keep connected and exchange information. Driven by the rapid wireless technology development and diffusion of mobile devices, social networks experienced a tremendous change based on mobile sensor computing. More and more mobile sensor network applications have appeared with the emergence of a huge amount of users. Therefore, an in-depth discussion on the human-computer interaction (HCI) issues of mobile sensor computing is required. The target of this study is to extend the discussions on HCI by examining the relationships of users' compound attitudes (i.e., affective attitudes, cognitive attitude), engagement and electronic word of mouth (eWOM) behaviors in the context of mobile sensor computing. A conceptual model is developed, based on which, 313 valid questionnaires are collected. The research discusses the level of impact on the eWOM of mobile sensor computing by considering user-technology issues, including the compound attitude and engagement, which can bring valuable discussions on the HCI of mobile sensor computing in further study. Besides, we find that user engagement plays a mediating role between the user's compound attitudes and eWOM. The research result can also help the mobile sensor computing industry to develop effective strategies and build strong consumer user-product (brand) relationships.

  2. High-Mobility Two-Dimensional Electron Gases at ZnO/ZnMgO Interfaces for Ultra-Fast Electronics Applications

    Science.gov (United States)

    2014-11-17

    mobilities can be obtained in the future by controlling the competing effects of interface strain and electron confinement. Ongoing work therefore... strain . This will necessitate the growth of a thin film of ZnO between the ZnO single crystal substrate and the ZnMgO thin film. 15...profile of Mg. .............................................................................................. 8 Figure 5: Longitudinal magnetoresistance

  3. Electronic Reading and Digital Library Technologies: Understanding Learner Expectation and Usage Intent for Mobile Learning

    Science.gov (United States)

    Hyman, Jack A.; Moser, Mary T.; Segala, Laura N.

    2014-01-01

    Mobile information technology is changing the education landscape by offering learners the opportunity to engage in asynchronous, ubiquitous instruction. While there is a proliferation of mobile content management systems being developed for the mobile Web and stand-alone mobile applications, few studies have addressed learner expectations and…

  4. Transformational Electronics: Towards Flexible Low-Cost High Mobility Channel Materials

    KAUST Repository

    Nassar, Joanna M.

    2014-05-01

    For the last four decades, Si CMOS technology has been advancing with Moore’s law prediction, working itself down to the sub-20 nm regime. However, fundamental problems and limitations arise with the down-scaling of transistors and thus new innovations needed to be discovered in order to further improve device performance without compromising power consumption and size. Thus, a lot of studies have focused on the development of new CMOS compatible architectures as well as the discovery of new high mobility channel materials that will allow further miniaturization of CMOS transistors and improvement of device performance. Pushing the limits even further, flexible and foldable electronics seem to be the new attractive topic. By being able to make our devices flexible through a CMOS compatible process, one will be able to integrate hundreds of billions of more transistors in a small volumetric space, allowing to increase the performance and speed of our electronics all together with making things thinner, lighter, smaller and even interactive with the human skin. Thus, in this thesis, we introduce for the first time a cost-effective CMOS compatible approach to make high-k/metal gate devices on flexible Germanium (Ge) and Silicon-Germanium (SiGe) platforms. In the first part, we will look at the various approaches in the literature that has been developed to get flexible platforms, as well as we will give a brief overview about epitaxial growth of Si1-xGex films. We will also examine the electrical properties of the Si1-xGex alloys up to Ge (x=1) and discuss how strain affects the band structure diagram, and thus the mobility of the material. We will also review the material growth properties as well as the state-of-the-art results on high mobility metal-oxide semiconductor capacitors (MOSCAPs) using strained SiGe films. Then, we will introduce the flexible process that we have developed, based on a cost-effective “trench-protect-release-reuse” approach, utilizing

  5. Bioinformatics paper exceeds 500 in citation index

    OpenAIRE

    Whyte, Barry James

    2010-01-01

    A scientific paper that includes contributions from scientists at the Virginia Bioinformatics Institute at Virginia Tech, has exceeded 500 citations in the ISI Web of Knowledge, an online academic database that documents the impact of scientific publications.

  6. Evidence for mobile electrons in p-type GaN:Mg

    Science.gov (United States)

    Zvanut, Mary Ellen; Willoughby, William

    2012-02-01

    Although Mg-doping is the only successful means of achieving p-type conductivity in GaN, little is known about the local environment of the impurity. Our work focuses on a unique phenomena revealed in the electron paramagnetic resonance (EPR) spectrum attributed to Mg: an angular dependent line-shape suggesting the presence of free carriers. 10 GHz EPR measurements were made at 4 K with the magnetic field in the plane of the c-axis. Samples included 0.5 -- 1.5 um thick Mg-doped GaN films grown on sapphire by molecular beam epitaxy or chemical vapor deposition. As expected, the angular dependence of the g value reflects axial symmetry. Unexpected is the line shape change from pure Lorentzian with the magnetic field 30^o from the c-axis to increasingly Dysonian upon rotation. The latter reflects the presence of mobile carriers due to, for instance, an interfacial conducting layer, polarization charge, or loosely bound electrons from Ga near neighbors. The new EPR analysis suggests local fields surround the Mg impurity which influence the acceptor's response.

  7. Piezotronic Effect tuned AlGaN/GaN High Electron Mobility Transistor.

    Science.gov (United States)

    Jiang, Chunyan; Liu, Ting; Du, Chunhua; Huang, Xin; Liu, Mengmeng; Zhao, Zhenfu; Li, Linxuan; Pu, Xiong; Zhai, Junyi; Hu, Weiguo; Wang, Zhong Lin

    2017-09-05

    The piezotronic effect is about utilizing strain-induced piezoelectric polarization charges to tune the carrier transportation across the interface/junction. We fabricated a high performance AlGaN/GaN High Electron Mobility Transistor (HEMT), and the transport property was proven to be enhanced by applying an external stress for the first time. The enhanced source-drain current was also observed at any gate voltage and the maximum enhancement of the saturation current was up to 21 % with 15 N applied stress (0.18 GPa at center) at -1 V gate voltage. The physical mechanism of HEMT with/without external compressive stress conditions was carefully illustrated and further confirmed by a self-consistent solution of the Schrödinger-Poisson equations. This study proves the cause-and-effect relationship between the piezoelectric polarization effect and two-dimensional electron gas formation, which provides a tunable solution to enhance the device performance. The strain tuned HEMT has potential applications in human-machine interface and the security control of the power system. © 2017 IOP Publishing Ltd.

  8. Basic Equations for the Modeling of Gallium Nitride (gan) High Electron Mobility Transistors (hemts)

    Science.gov (United States)

    Freeman, Jon C.

    2003-01-01

    Gallium nitride (GaN) is a most promising wide band-gap semiconductor for use in high-power microwave devices. It has functioned at 320 C, and higher values are well within theoretical limits. By combining four devices, 20 W has been developed at X-band. GaN High Electron Mobility Transistors (HEMTs) are unique in that the two-dimensional electron gas (2DEG) is supported not by intentional doping, but instead by polarization charge developed at the interface between the bulk GaN region and the AlGaN epitaxial layer. The polarization charge is composed of two parts: spontaneous and piezoelectric. This behavior is unlike other semiconductors, and for that reason, no commercially available modeling software exists. The theme of this document is to develop a self-consistent approach to developing the pertinent equations to be solved. A Space Act Agreement, "Effects in AlGaN/GaN HEMT Semiconductors" with Silvaco Data Systems to implement this approach into their existing software for III-V semiconductors, is in place (summer of 2002).

  9. Piezotronic effect tuned AlGaN/GaN high electron mobility transistor

    Science.gov (United States)

    Jiang, Chunyan; Liu, Ting; Du, Chunhua; Huang, Xin; Liu, Mengmeng; Zhao, Zhenfu; Li, Linxuan; Pu, Xiong; Zhai, Junyi; Hu, Weiguo; Wang, Zhong Lin

    2017-11-01

    The piezotronic effect utilizes strain-induced piezoelectric polarization charges to tune the carrier transportation across the interface/junction. We fabricated a high-performance AlGaN/GaN high electron mobility transistor (HEMT), and the transport property was proven to be enhanced by applying an external stress for the first time. The enhanced source-drain current was also observed at any gate voltage and the maximum enhancement of the saturation current was up to 21% with 15 N applied stress (0.18 GPa at center) at -1 V gate voltage. The physical mechanism of HEMT with/without external compressive stress conditions was carefully illustrated and further confirmed by a self-consistent solution of the Schrödinger-Poisson equations. This study proves the cause-and-effect relationship between the piezoelectric polarization effect and 2D electron gas formation, which provides a tunable solution to enhance the device performance. The strain tuned HEMT has potential applications in human-machine interface and the security control of the power system.

  10. Power Dependence of the Electron Mobility Profile in a Hall Thruster

    Science.gov (United States)

    Jorns, Benjamin A.; Hofery, Richard H.; Mikellides, Ioannis G.

    2014-01-01

    The electron mobility profile is estimated in a 4.5 kW commercial Hall thruster as a function of discharge power. Internal measurements of plasma potential and electron temperature are made in the thruster channel with a high-speed translating probe. These measurements are presented for a range of throttling conditions from 150 - 400 V and 0.6 - 4.5 kW. The fluid-based solver, Hall2De, is used in conjunction with these internal plasma parameters to estimate the anomalous collision frequency profile at fixed voltage, 300 V, and three power levels. It is found that the anomalous collision frequency profile does not change significantly upstream of the location of the magnetic field peak but that the extent and magnitude of the anomalous collision frequency downstream of the magnetic peak does change with thruster power. These results are discussed in the context of developing phenomenological models for how the collision frequency profile depends on thruster operating conditions.

  11. Spin frustration and fermionic entanglement in an exactly solved hybrid diamond chain with the localized Ising spins and mobile electrons

    OpenAIRE

    Torrico, J.; Rojas, M.; Pereira, M. S. S.; Strecka, J.; Lyra, M. L.

    2015-01-01

    The strongly correlated spin-electron system on a diamond chain containing localized Ising spins on its nodal lattice sites and mobile electrons on its interstitial sites is exactly solved in a magnetic field using the transfer-matrix method. We have investigated in detail all available ground states, the magnetization processes, the spin-spin correlation functions around an elementary plaquette, fermionic quantum concurrence and spin frustration. It is shown that the fermionic entanglement b...

  12. The Impact of Electronic Mobility Devices for Persons Who Are Visually Impaired: A Systematic Review of Effects and Effectiveness

    Science.gov (United States)

    Roentgen, Uta R.; Gelderblom, Gert Jan; Soede, Mathijs; de Witte, Luc P.

    2009-01-01

    A systematic review of the international literature was conducted to investigate the effects and effectiveness of electronic mobility devices. Of the 13 studies that were reviewed, all but one demonstrated effects of the use of these devices, and generally, users evaluated the devices' functionality as beneficial. (Contains 1 table.)

  13. The effect of charged quantum dots on the mobility of a two-dimensional electron gas: How important is the Coulomb scattering?

    Energy Technology Data Exchange (ETDEWEB)

    Kurzmann, A., E-mail: annika.kurzmann@uni-due.de; Beckel, A.; Lorke, A.; Geller, M. [Fakultät für Physik and CeNIDE, Universität Duisburg-Essen, Lotharstraße 1, Duisburg 47048 (Germany); Ludwig, A.; Wieck, A. D. [Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum (Germany)

    2015-02-07

    We have investigated the influence of a layer of charged self-assembled quantum dots (QDs) on the mobility of a nearby two-dimensional electron gas (2DEG). Time-resolved transconductance spectroscopy was used to separate the two contributions of the change in mobility, which are: (i) The electrons in the QDs act as Coulomb scatterers for the electrons in the 2DEG. (ii) The screening ability and, hence, the mobility of the 2DEG decreases when the charge carrier density is reduced by the charged QDs, i.e., the mobility itself depends on the charge carrier concentration. Surprisingly, we find a negligible influence of the Coulomb scattering on the mobility for a 2DEG, separated by a 30 nm tunneling barrier to the layer of QDs. This means that the mobility change is completely caused by depletion, i.e., reduction of the charge carrier density in the 2DEG, which indirectly influences the mobility.

  14. Development and Evaluation of e-CA, an Electronic Mobile-Based Food Record

    Directory of Open Access Journals (Sweden)

    Sophie Bucher Della Torre

    2017-01-01

    Full Text Available Measures that capture diet as validly and reliably as possible are cornerstones of nutritional research, and mobile-based devices offer new opportunities to improve and simplify data collection. The balance between precision and acceptability of these data collection tools remains debated, and rigorous validations are warranted. Our objective was to develop and evaluate an electronic mobile-based food record for a research setting. We developed e-CA, which includes almost 900 foods and beverages classified in 14 categories and 60 subcategories. e-CA was evaluated using three different methods: (1 usability and acceptability through a logbook and qualitative interviews; (2 dietary intake accuracy through comparison with 2 unannounced 24-h phone recalls on overlapping days; and (3 reliability and process comparison with a paper-based food record in a laboratory setting with a randomized design. e-CA proved to be intuitive and practical and was perceived as modern, trendy, and fun. Comparisons of e-CA with 24-h telephone recalls or paper-based food records in a laboratory setting with two small convenient samples showed good agreement but highlighted the well-known difficulty of estimating portion sizes and a necessary learning time to use the app. e-CA is a functional tool that has the potential to facilitate food intake measurement for research by increasing the pleasure of using the food record tool and reducing the perceived burden for the participants. It also decreases the workload, costs and the risk of transcription errors for researchers.

  15. The role of regioregularity, crystallinity, and chain orientation on electron transport in a high-mobility n-type copolymer.

    Science.gov (United States)

    Steyrleuthner, Robert; Di Pietro, Riccardo; Collins, Brian A; Polzer, Frank; Himmelberger, Scott; Schubert, Marcel; Chen, Zhihua; Zhang, Shiming; Salleo, Alberto; Ade, Harald; Facchetti, Antonio; Neher, Dieter

    2014-03-19

    We investigated the correlation between the polymer backbone structural regularity and the charge transport properties of poly{[N,N'-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} [P(NDI2OD-T2)], a widely studied semiconducting polymer exhibiting high electron mobility and an unconventional micromorphology. To understand the influence of the chemical structure and crystal packing of conventional regioregular P(NDI2OD-T2) [RR-P(NDI2OD-T2)] on the charge transport, the corresponding regioirregular polymer RI-P(NDI2OD-T2) was synthesized. By combining optical, X-ray, and transmission electron microscopy data, we quantitatively characterized the aggregation, crystallization, and backbone orientation of all of the polymer films, which were then correlated to the electron mobilities in electron-only diodes. By carefully selecting the preparation conditions, we were able to obtain RR-P(NDI2OD-T2) films with similar crystalline structure along the three crystallographic axes but with different orientations of the polymer chains with respect to the substrate surface. RI-P(NDI2OD-T2), though exhibiting a rather similar LUMO structure and energy compared with the regioregular counterpart, displayed a very different packing structure characterized by the formation of ordered stacks along the lamellar direction without detectible π-stacking. Vertical electron mobilities were extracted from the space-charge-limited currents in unipolar devices. We demonstrate the anisotropy of the charge transport along the different crystallographic directions and how the mobility depends on π-stacking but is insensitive to the degree or coherence of lamellar stacking. The comparison between the regioregular and regioirregular polymers also shows how the use of large planar functional groups leads to improved charge transport, with mobilities that are less affected by chemical and structural disorder with respect to classic semicrystalline polymers such

  16. Spin frustration and fermionic entanglement in an exactly solved hybrid diamond chain with localized Ising spins and mobile electrons

    Science.gov (United States)

    Torrico, J.; Rojas, M.; Pereira, M. S. S.; Strečka, J.; Lyra, M. L.

    2016-01-01

    The strongly correlated spin-electron system on a diamond chain containing localized Ising spins on its nodal lattice sites and mobile electrons on its interstitial sites is exactly solved in a magnetic field using the transfer-matrix method. We have investigated in detail all available ground states, the magnetization processes, the spin-spin correlation functions around an elementary plaquette, fermionic quantum concurrence, and spin frustration. It is shown that the fermionic entanglement between mobile electrons hopping on interstitial sites and the kinetically induced spin frustration are closely related yet independent phenomena. In the ground state, quantum entanglement only appears within a frustrated unsaturated paramagnetic phase, while thermal fluctuations can promote some degree of quantum entanglement above the nonfrustrated ground states with saturated paramagnetic or classical ferrimagnetic spin arrangements.

  17. The impact of surface-roughness scattering on the low-field electron mobility in nano-scale Si MOSFETs

    Science.gov (United States)

    Kannan, Gokula; Vasileska, Dragica

    2017-09-01

    A state-of-the-art simulator for the calculation of low-field mobility in inversion layers is presented in this work that accounts for the collisional broadening of the electronic states via the solution of the Dyson equation for the retarded Green's function. The self-consistent Born approximation is used for the calculation of the self-energy contributions due to Coulomb, surface-roughness, acoustic, and non-polar optical phonon scattering. The simulated mobility results for three generations of MOSFET devices are in agreement with the experimental data. At nanoscale dimensions, surface-roughness scattering dominates the collisional broadening of the states and the renormalization of the spectrum.

  18. ADDED VALUE-BASED APROACH TO ANALYZE ELECTRONIC COMMERCE AND MOBILE COMMERCE BUSINESS MODELS

    Directory of Open Access Journals (Sweden)

    Moritz Weizmann

    2004-03-01

    Full Text Available

    Se propone aplicar la teoría del valor informacional agregado (Theory of Informational Added Values, IAV al Electronic Commerce (EC y al Mobile Commerce (MC. El trabajo presentado es una propuesta para acercarse a modelos de negocio, con el foco de criterios típicos de evaluación para modelos de negocio de Internet y del MC. Es también conveniente para comparar modelos de negocio distintos y para poner el valor añadido para los participantes en un contexto. De esta manera, se establecen criterios objetivos que reducen la subjetividad y permiten hacer ciertas predicciones. El artículo termina con un análisis crítico del estado del arte y un comentario sobre las perspectivas futuras.

  19. AUTOMATED IRRIGATION SYSTEM CONSTITUTED OF ELECTRONIC ELEMENTS, MOBILE DEVICE AND THE CONSTRUCTION OF SPRINKLER

    Directory of Open Access Journals (Sweden)

    Alma Delia González

    2017-12-01

    Full Text Available This document presents the development of an automated irrigation system, which consisted of a sprinkler that has a range of 16 meters in diameter using only sprinklers per one hectare of land, water pump, hose, water containers, electro valves, relays, electronic components such as humidity and temperature sensor, ultrasonic sensor, LCD screen, microcontroller (Arduino Mega, for communication a bluetooth module and a mobile device (Android. The agile methodology used was Extreme XP Programming, following its 4 phases, planning, design, development and testing. With this an automated irrigation system was used that was developed to monitor temperature, humidity and to generate a saving in the water thanks to the census of the container of the same, as well as the reduction of maintenance costs, this can be activated or deactivated by the user regardless of the conditions. The system complies with the characteristics of a utility model, because these models are all those objects, tools, appliances or tools that, as a result of a change in their layout, configuration, structure or form, present a different function with respect to the parts that integrate it or advantages in terms of its usefulness and thanks to the search carried out in IMPI. In the study of the state of the art the search was made in the data bases of Mexico in SIGA (Information System of the Gazette of the Industrial Property and internationally in Thomson, the results showed that there were similar sy

  20. High electron mobility ZnO film for high-performance inverted polymer solar cells

    Science.gov (United States)

    Lv, Peiwen; Chen, Shan-Ci; Zheng, Qingdong; Huang, Feng; Ding, Kai

    2015-04-01

    High-quality ZnO films (ZnO-MS) are prepared via magnetron sputtering deposition with a high mobility of about 2 cm2/(V.s) and are used as electron transport layer for inverted polymer solar cells (PSCs) with polymer poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester as the active layer. A significant improvement of JSC, about 20% enhancement in contrast to the devices built on sol-gel derived ZnO film (ZnO-Sol), is found in the ZnO-MS based device. High performance ZnO-MS based PSCs exhibit power conversion efficiency (PCE) up to 8.55%, which is much better than the device based on ZnO-Sol (PCE = 7.78%). Further research on cathode materials is promising to achieve higher performance.

  1. A mobile and asynchronous electronic data capture system for epidemiologic studies.

    Science.gov (United States)

    Meyer, Jens; Fredrich, Daniel; Piegsa, Jens; Habes, Mohamad; van den Berg, Neeltje; Hoffmann, Wolfgang

    2013-06-01

    A Central Data Management (CDM) system based on electronic data capture (EDC) software and study specific databases is an essential component for assessment and management of large data volumes in epidemiologic studies. Conventional CDM systems using web applications for data capture depend on permanent access to a network. However, in many study settings permanent network access cannot be guaranteed, e.g. when participants/patients are visited in their homes. In such cases a different concept for data capture is needed. The utilized EDC software must be able to ensure data capture as stand-alone instance and to synchronize captured data with the server at a later point in time. This article describes the design of the mobile information capture (MInCa) system an EDC software meeting these requirements. In particular, we focus on client and server design, data synchronization, and data privacy as well as data security measures. The MInCa software has already proven its efficiency in epidemiologic studies revealing strengths and weaknesses concerning both concept and practical application which will be addressed in this article. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  2. Computational Search for Two-Dimensional MX2 Semiconductors with Possible High Electron Mobility at Room Temperature

    Directory of Open Access Journals (Sweden)

    Zhishuo Huang

    2016-08-01

    Full Text Available Neither of the two typical two-dimensional materials, graphene and single layer MoS 2 , are good enough for developing semiconductor logical devices. We calculated the electron mobility of 14 two-dimensional semiconductors with composition of MX 2 , where M (=Mo, W, Sn, Hf, Zr and Pt are transition metals, and Xs are S, Se and Te. We approximated the electron phonon scattering matrix by deformation potentials, within which long wave longitudinal acoustical and optical phonon scatterings were included. Piezoelectric scattering in the compounds without inversion symmetry is also taken into account. We found that out of the 14 compounds, WS 2 , PtS 2 and PtSe 2 are promising for logical devices regarding the possible high electron mobility and finite band gap. Especially, the phonon limited electron mobility in PtSe 2 reaches about 4000 cm 2 ·V - 1 ·s - 1 at room temperature, which is the highest among the compounds with an indirect bandgap of about 1.25 eV under the local density approximation. Our results can be the first guide for experiments to synthesize better two-dimensional materials for future semiconductor devices.

  3. The Current Collapse in AlGaN/GaN High-Electron Mobility Transistors Can Originate from the Energy Relaxation of Channel Electrons?

    Science.gov (United States)

    Mao, Ling-Feng; Ning, Huan-Sheng; Wang, Jin-Yan

    2015-01-01

    Influence of the energy relaxation of the channel electrons on the performance of AlGaN/GaN high-electron mobility transistors (HEMTs) has been investigated using self-consistent solution to the coupled Schrödinger equation and Poisson equation. The first quantized energy level in the inversion layer rises and the average channel electron density decreases when the channel electric field increases from 20 kV/cm to 120 kV/cm. This research also demonstrates that the energy relaxation of the channel electrons can lead to current collapse and suggests that the energy relaxation should be considered in modeling the performance of AlGaN/GaN HEMTs such as, the gate leakage current, threshold voltage, source-drain current, capacitance-voltage curve, etc.

  4. The Current Collapse in AlGaN/GaN High-Electron Mobility Transistors Can Originate from the Energy Relaxation of Channel Electrons?

    Directory of Open Access Journals (Sweden)

    Ling-Feng Mao

    Full Text Available Influence of the energy relaxation of the channel electrons on the performance of AlGaN/GaN high-electron mobility transistors (HEMTs has been investigated using self-consistent solution to the coupled Schrödinger equation and Poisson equation. The first quantized energy level in the inversion layer rises and the average channel electron density decreases when the channel electric field increases from 20 kV/cm to 120 kV/cm. This research also demonstrates that the energy relaxation of the channel electrons can lead to current collapse and suggests that the energy relaxation should be considered in modeling the performance of AlGaN/GaN HEMTs such as, the gate leakage current, threshold voltage, source-drain current, capacitance-voltage curve, etc.

  5. Thickness-dependent electron mobility of single and few-layer MoS2 thin-film transistors

    Directory of Open Access Journals (Sweden)

    Ji Heon Kim

    2016-06-01

    Full Text Available We investigated the dependence of electron mobility on the thickness of MoS2 nanosheets by fabricating bottom-gate single and few-layer MoS2 thin-film transistors with SiO2 gate dielectrics and Au electrodes. All the fabricated MoS2 transistors showed on/off-current ratio of ∼107 and saturated output characteristics without high-k capping layers. As the MoS2 thickness increased from 1 to 6 layers, the field-effect mobility of the fabricated MoS2 transistors increased from ∼10 to ∼18 cm2V−1s−1. The increased subthreshold swing of the fabricated transistors with MoS2 thickness suggests that the increase of MoS2 mobility with thickness may be related to the dependence of the contact resistance and the dielectric constant of MoS2 layer on its thickness.

  6. Mobility-electron density relation probed via controlled oxygen vacancy doping in epitaxial BaSnO3

    Directory of Open Access Journals (Sweden)

    Koustav Ganguly

    2017-05-01

    Full Text Available The recently discovered high room temperature mobility in wide band gap semiconducting BaSnO3 is of exceptional interest for perovskite oxide heterostructures. Critical open issues with epitaxial films include determination of the optimal dopant and understanding the mobility-electron density (μ-n relation. These are addressed here through a transport study of BaSnO3(001 films with oxygen vacancy doping controlled via variable temperature vacuum annealing. Room temperature n can be tuned from 5 × 1019 cm−3 to as low as 2 × 1017 cm−3, which is shown to drive a weak- to strong-localization transition, a 104-fold increase in resistivity, and a factor of 28 change in μ. The data reveal μ ∝ n0.65 scaling over the entire n range probed, important information for understanding mobility-limiting scattering mechanisms.

  7. Modeling of high composition AlGaN channel high electron mobility transistors with large threshold voltage

    Energy Technology Data Exchange (ETDEWEB)

    Bajaj, Sanyam, E-mail: bajaj.10@osu.edu; Hung, Ting-Hsiang; Akyol, Fatih; Nath, Digbijoy; Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2014-12-29

    We report on the potential of high electron mobility transistors (HEMTs) consisting of high composition AlGaN channel and barrier layers for power switching applications. Detailed two-dimensional (2D) simulations show that threshold voltages in excess of 3 V can be achieved through the use of AlGaN channel layers. We also calculate the 2D electron gas mobility in AlGaN channel HEMTs and evaluate their power figures of merit as a function of device operating temperature and Al mole fraction in the channel. Our models show that power switching transistors with AlGaN channels would have comparable on-resistance to GaN-channel based transistors for the same operation voltage. The modeling in this paper shows the potential of high composition AlGaN as a channel material for future high threshold enhancement mode transistors.

  8. Application of Failure Mode and Effects Analysis to Intraoperative Radiation Therapy Using Mobile Electron Linear Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ciocca, Mario, E-mail: mario.ciocca@cnao.it [Unit of Medical Physics, Centro Nazionale di Adroterapia Oncologica (CNAO) Foundation, via Campeggi, 27100 Pavia (Italy); Cantone, Marie-Claire; Veronese, Ivan [Department of Physics, Universita degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Istituto Nazionale di Fisica Nucleare, INFN Milano, via Celoria 16, 20133 Milano (Italy); Cattani, Federica; Pedroli, Guido [Unit of Medical Physics, European Institute of Oncology, via Ripamonti 435, 20141 Milano (Italy); Molinelli, Silvia [Unit of Medical Physics, Centro Nazionale di Adroterapia Oncologica (CNAO) Foundation, via Campeggi, 27100 Pavia (Italy); Vitolo, Viviana [Unit of Radiotherapy, Centro Nazionale di Adroterapia Oncologica (CNAO) Foundation, via Campeggi, 27100 Pavia (Italy); Orecchia, Roberto [Division of Radiation Oncology, European Institute of Oncology, via Ripamonti 435, 20141 Milano (Italy); Scientific Direction, Centro Nazionale di Adroterapia Oncologica (CNAO) Foundation, via Campeggi, 27100 Pavia (Italy); Faculty of Medicine, Universita degli Studi di Milano, via Ripamonti 435, 20141 Milano (Italy)

    2012-02-01

    Purpose: Failure mode and effects analysis (FMEA) represents a prospective approach for risk assessment. A multidisciplinary working group of the Italian Association for Medical Physics applied FMEA to electron beam intraoperative radiation therapy (IORT) delivered using mobile linear accelerators, aiming at preventing accidental exposures to the patient. Methods and Materials: FMEA was applied to the IORT process, for the stages of the treatment delivery and verification, and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system, based on the product of three parameters (severity, frequency of occurrence and detectability, each ranging from 1 to 10); 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. Results: Twenty-four subprocesses were identified. Ten potential failure modes were found and scored, in terms of RPN, in the range of 42-216. The most critical failure modes consisted of internal shield misalignment, wrong Monitor Unit calculation and incorrect data entry at treatment console. Potential causes of failure included shield displacement, human errors, such as underestimation of CTV extension, mainly because of lack of adequate training and time pressures, failure in the communication between operators, and machine malfunctioning. The main effects of failure were represented by CTV underdose, wrong dose distribution and/or delivery, unintended normal tissue irradiation. As additional safety measures, the utilization of a dedicated staff for IORT, double-checking of MU calculation and data entry and finally implementation of in vivo dosimetry were suggested. Conclusions: FMEA appeared as a useful tool for prospective evaluation of patient safety in radiotherapy. The

  9. SU-F-T-80: A Mobile Application for Intra-Operative Electron Radiotherapy Treatment Planning

    Energy Technology Data Exchange (ETDEWEB)

    Williams, C [Brigham and Women’s Hospital & Dana Farber Cancer Institute, Boston, MA (United States); Harvard Medical School, Boston, MA (United States); Crowley, E; Wolfgang, J [Harvard Medical School, Boston, MA (United States); Massachusetts General Hospital, Boston, MA (United States)

    2016-06-15

    Purpose: Intraoperative electron radiotherapy (IORT) poses a unique set of challenges for treatment planning. Planning must be performed in a busy operating room environment over a short timeframe often with little advance knowledge of the treatment depth or applicator size. Furthermore, IORT accelerators can have a large number of possible applicators, requiring extensive databooks that must be searched for the appropriate dosimetric parameters. The goal of this work is to develop a software tool to assist in the planning process that is suited to the challenges faced in the IORT environment. Methods: We developed a mobile application using HTML5 and Javascript that can be deployed to tablet devices suitable for use in the operating room. The user selects the desired treatment parameters cone diameter, bevel angle, and energy (a total of 141 datasets) and desired bolus. The application generates an interactive display that allows the user to dynamically select points on the depth-dose curve and to visualize the shape of the corresponding isodose contours. The user can indicate a prescription isodose line or depth. The software performs a monitor unit calculation and generates a PDF report. Results: We present our application, which is now used routinely in our IORT practice. It has been employed successfully in over 23 cases. The interactivity of the isodose distributions was found to be of particular use to physicians who are less-frequent IORT users, as well as for the education of residents and trainees. Conclusion: This software has served as a useful tool in IORT planning, and demonstrates the need for treatment planning tools that are designed for the specialized challenges encountered in IORT. This software is the subject of a license agreement with the IntraOp Medical Corporation. This software is the subject of a license agreement between Massachusetts General Hospital / Partners Healthcare and the IntraOp Medical Corporation. CLW is consulting on

  10. Improving crystallization and electron mobility of indium tin oxide by carbon dioxide and hydrogen dual-step plasma treatment

    Science.gov (United States)

    Wang, Fengyou; Du, Rongchi; Ren, Qianshang; Wei, Changchun; Zhao, Ying; Zhang, Xiaodan

    2017-12-01

    Obtaining high conductivity indium tin oxide (ITO) films simultaneously with a "soft-deposited" (low temperature, low ions bombardment) and cost-efficient deposition process are critical aspect for versatile photo-electronic devices application. Usually, the low-cost "soft-deposited" process could be achieved via evaporation technique, but with scarifying the conductivity of the films. Here, we show a CO2 and H2 two-step plasma (TSP) post-treatment applied to ITO films prepared by reactive thermal evaporation (RTE), allows to meet the special trade-off between the deposition techniques and the electrical properties. Upon treatment, an increase in electron concentration and electron mobility is observed, which subsequently resulting a low sheet resistivity. The mobility reaches high values of 80.9 cm2/Vs for the TSP treated ∼100 nm thickness samples. From a combination of X-ray photoelectron spectroscopy and opto-electronic measurements, it demonstrated that: during the TSP process, the first-step CO2 plasma treatment could promote the crystallinity of the RTE ITO films. While the electron traps density at grain boundaries of polycrystalline RTE ITO films could be passivated by hydrogen atom during the second-step H2 plasma treatment. These results inspired that the TSP treatment process has significant application prospects owing to the outstanding electrical properties enhancement for "soft-deposited" RTE ITO films.

  11. Understanding Local and Macroscopic Electron Mobilities in the Fullerene Network of Conjugated Polymer-based Solar Cells. Time-Resolved Microwave Conductivity and Theory

    Energy Technology Data Exchange (ETDEWEB)

    Aguirre, Jordan C. [Univ. of California, Los Angeles, CA (United States); Arntsen, Christopher D. [Univ. of California, Los Angeles, CA (United States); Hernandez, Samuel [Univ. of California, Los Angeles, CA (United States); Huber, Rachel [Univ. of California, Los Angeles, CA (United States); Nardes, Alexandre M. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Halim, Merissa [Univ. of California, Los Angeles, CA (United States); Kilbride, Daniel [Univ. of California, Los Angeles, CA (United States); Rubin, Yves [Univ. of California, Los Angeles, CA (United States); Tolbert, Sarah H. [Univ. of California, Los Angeles, CA (United States); Kopidakis, Nikos [National Renewable Energy Lab. (NREL), Golden, CO (United States); Schwartz, Benjamin J. [Univ. of California, Los Angeles, CA (United States); Neuhauser, Daniel [Univ. of California, Los Angeles, CA (United States)

    2013-09-23

    The efficiency of bulk heterojunction (BHJ) organic photovoltaics is sensitive to the morphology of the fullerene network that transports electrons through the device. This sensitivity makes it difficult to distinguish the contrasting roles of local electron mobility (how easily electrons can transfer between neighboring fullerene molecules) and macroscopic electron mobility (how well-connected is the fullerene network on device length scales) in solar cell performance. In this work, a combination of density functional theory (DFT) calculations, flash-photolysis time-resolved microwave conductivity (TRMC) experiments, and space-charge-limit current (SCLC) mobility estimates are used to examine the roles of local and macroscopic electron mobility in conjugated polymer/fullerene BHJ photovoltaics. The local mobility of different pentaaryl fullerene derivatives (so-called ‘shuttlecock’ molecules) is similar, so that differences in solar cell efficiency and SCLC mobilities result directly from the different propensities of these molecules to self-assemble on macroscopic length scales. These experiments and calculations also demonstrate that the local mobility of phenyl-C60 butyl methyl ester (PCBM) is an order of magnitude higher than that of other fullerene derivatives, explaining why PCBM has been the acceptor of choice for conjugated polymer BHJ devices even though it does not form an optimal macroscopic network. The DFT calculations indicate that PCBM's superior local mobility comes from the near-spherical nature of its molecular orbitals, which allow strong electronic coupling between adjacent molecules. In combination, DFT and TRMC techniques provide a tool for screening new fullerene derivatives for good local mobility when designing new molecules that can improve on the macroscopic electron mobility offered by PCBM.

  12. Determination of the band alignment of a-IGZO/a-IGMO heterojunction for high-electron mobility transistor application

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi-Yu; Qian, Ling-Xuan; Liu, Xing-Zhao [School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu (China); State Key Laboratory of Electronic Thin Films and Integrated Devices, Chengdu (China)

    2017-10-15

    In the past decade, amorphous InGaZnO thin film transistors (a-IGZO TFTs) have become a very promising candidate for application in flat panel displays (FPDs). However, it is difficult to break through the mobility bottleneck of a-IGZO TFTs to obtain mobilities higher than 100 cm{sup 2} V{sup -1} s{sup -1}, thus limiting their use in more advanced applications. Construction of a high-electron mobility transistor (HEMT) based on a heterojunction structure could provide a solution for this problem. In this work, the band alignment of a-IGZO and amorphous InGaMgO (a-IGMO) heterojunction has been investigated using X-ray photoelectron spectroscopy (XPS) and transmission spectra measurements. The valence band (ΔE{sub V}) and conduction band offsets (ΔE{sub C}) were determined as 0.09 and 0.83 eV, respectively. The ΔE{sub C} was large enough to construct a potential well that could favor the appearance of a two-dimensional electron gas (2DEG). Hence, the achievement of an HEMT based on a-IGZO/a-IGMO heterojunction can be expected. Moreover, band bending contributed greatly to such a large ΔE{sub C}, and thus to the formation of electrical confinement structure. Our findings suggest that a-IGZO/a-IGMO heterojunction is a potential candidate for constructing a HEMT and thus breaking through the mobility bottleneck of a-IGZO-based TFTs for the applications in next-generation electronic products. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. High Electron Mobility Thin-Film Transistors Based on Solution-Processed Semiconducting Metal Oxide Heterojunctions and Quasi-Superlattices

    KAUST Repository

    Lin, Yen-Hung

    2015-05-26

    High mobility thin-film transistor technologies that can be implemented using simple and inexpensive fabrication methods are in great demand because of their applicability in a wide range of emerging optoelectronics. Here, a novel concept of thin-film transistors is reported that exploits the enhanced electron transport properties of low-dimensional polycrystalline heterojunctions and quasi-superlattices (QSLs) consisting of alternating layers of In2O3, Ga2O3, and ZnO grown by sequential spin casting of different precursors in air at low temperatures (180–200 °C). Optimized prototype QSL transistors exhibit band-like transport with electron mobilities approximately a tenfold greater (25–45 cm2 V−1 s−1) than single oxide devices (typically 2–5 cm2 V−1 s−1). Based on temperature-dependent electron transport and capacitance-voltage measurements, it is argued that the enhanced performance arises from the presence of quasi 2D electron gas-like systems formed at the carefully engineered oxide heterointerfaces. The QSL transistor concept proposed here can in principle extend to a range of other oxide material systems and deposition methods (sputtering, atomic layer deposition, spray pyrolysis, roll-to-roll, etc.) and can be seen as an extremely promising technology for application in next-generation large area optoelectronics such as ultrahigh definition optical displays and large-area microelectronics where high performance is a key requirement.

  14. Characterization and reliability of aluminum gallium nitride/gallium nitride high electron mobility transistors

    Science.gov (United States)

    Douglas, Erica Ann

    Compound semiconductor devices, particularly those based on GaN, have found significant use in military and civilian systems for both microwave and optoelectronic applications. Future uses in ultra-high power radar systems will require the use of GaN transistors operated at very high voltages, currents and temperatures. GaN-based high electron mobility transistors (HEMTs) have proven power handling capability that overshadows all other wide band gap semiconductor devices for high frequency and high-power applications. Little conclusive research has been reported in order to determine the dominating degradation mechanisms of the devices that result in failure under standard operating conditions in the field. Therefore, it is imperative that further reliability testing be carried out to determine the failure mechanisms present in GaN HEMTs in order to improve device performance, and thus further the ability for future technologies to be developed. In order to obtain a better understanding of the true reliability of AlGaN/GaN HEMTs and determine the MTTF under standard operating conditions, it is crucial to investigate the interaction effects between thermal and electrical degradation. This research spans device characterization, device reliability, and device simulation in order to obtain an all-encompassing picture of the device physics. Initially, finite element thermal simulations were performed to investigate the effect of device design on self-heating under high power operation. This was then followed by a study of reliability of HEMTs and other tests structures during high power dc operation. Test structures without Schottky contacts showed high stability as compared to HEMTs, indicating that degradation of the gate is the reason for permanent device degradation. High reverse bias of the gate has been shown to induce the inverse piezoelectric effect, resulting in a sharp increase in gate leakage current due to crack formation. The introduction of elevated

  15. Modeling and Design of GaN High Electron Mobility Transistors and Hot Electron Transistors through Monte Carlo Particle-based Device Simulations

    Science.gov (United States)

    Soligo, Riccardo

    In this work, the insight provided by our sophisticated Full Band Monte Carlo simulator is used to analyze the behavior of state-of-art devices like GaN High Electron Mobility Transistors and Hot Electron Transistors. Chapter 1 is dedicated to the description of the simulation tool used to obtain the results shown in this work. Moreover, a separate section is dedicated the set up of a procedure to validate to the tunneling algorithm recently implemented in the simulator. Chapter 2 introduces High Electron Mobility Transistors (HEMTs), state-of-art devices characterized by highly non linear transport phenomena that require the use of advanced simulation methods. The techniques for device modeling are described applied to a recent GaN-HEMT, and they are validated with experimental measurements. The main techniques characterization techniques are also described, including the original contribution provided by this work. Chapter 3 focuses on a popular technique to enhance HEMTs performance: the down-scaling of the device dimensions. In particular, this chapter is dedicated to lateral scaling and the calculation of a limiting cutoff frequency for a device of vanishing length. Finally, Chapter 4 and Chapter 5 describe the modeling of Hot Electron Transistors (HETs). The simulation approach is validated by matching the current characteristics with the experimental one before variations of the layouts are proposed to increase the current gain to values suitable for amplification. The frequency response of these layouts is calculated, and modeled by a small signal circuit. For this purpose, a method to directly calculate the capacitance is developed which provides a graphical picture of the capacitative phenomena that limit the frequency response in devices. In Chapter 5 the properties of the hot electrons are investigated for different injection energies, which are obtained by changing the layout of the emitter barrier. Moreover, the large signal characterization of the

  16. Effect of Energy Alignment, Electron Mobility, and Film Morphology of Perylene Diimide Based Polymers as Electron Transport Layer on the Performance of Perovskite Solar Cells.

    Science.gov (United States)

    Guo, Qiang; Xu, Yingxue; Xiao, Bo; Zhang, Bing; Zhou, Erjun; Wang, Fuzhi; Bai, Yiming; Hayat, Tasawar; Alsaedi, Ahmed; Tan, Zhan'ao

    2017-03-29

    For organic-inorganic perovskite solar cells (PerSCs), the electron transport layer (ETL) plays a crucial role in efficient electron extraction and transport for high performance PerSCs. Fullerene and its derivatives are commonly used as ETL for p-i-n structured PerSCs. However, these spherical small molecules are easy to aggregate with high annealing temperature and thus induce morphology stability problems. N-type conjugated polymers are promising candidates to overcome these problems due to the tunable energy levels, controllable aggregation behaviors, and good film formation abilities. Herein, a series of perylene diimide (PDI) based polymers (PX-PDIs), which contain different copolymeried units (X), including vinylene (V), thiophene (T), selenophene (Se), dibenzosilole (DBS), and cyclopentadithiophene (CPDT), are introduced as ETL for p-i-n structured PerSCs. The effect of energy alignment, electron mobility, and film morphology of these ETLs on the photovoltaic performance of the PerSCs are fully investigated. Among the PX-PDIs, PV-PDI demonstrates the deeper LUMO energy level, the highly delocalized LUMO electron density, and a better planar structure, making it the best electron transport material for PerSCs. The planar heterojunction PerSC with PV-PDI as ETL achieves a power conversion efficiency (PCE) of 10.14%, among the best values for non-fullerene based PerSCs.

  17. The hibernating mobile phone: Dead storage as a barrier to efficient electronic waste recovery.

    Science.gov (United States)

    Wilson, Garrath T; Smalley, Grace; Suckling, James R; Lilley, Debra; Lee, Jacquetta; Mawle, Richard

    2017-02-01

    Hibernation, the dead storage period when a mobile phone is still retained by the user at its end-of-life, is both a common and a significant barrier to the effective flow of time-sensitive stock value within a circular economic model. In this paper we present the findings of a survey of 181 mobile phone owners, aged between 18-25years old, living and studying in the UK, which explored mobile phone ownership, reasons for hibernation, and replacement motives. This paper also outlines and implements a novel mechanism for quantifying the mean hibernation period based on the survey findings. The results show that only 33.70% of previously owned mobile phones were returned back into the system. The average duration of ownership of mobile phones kept and still in hibernation was 4years 11months, with average use and hibernation durations of 1year 11months, and 3years respectively; on average, mobile phones that are kept by the user are hibernated for longer than they are ever actually used as primary devices. The results also indicate that mobile phone replacement is driven primarily by physical (technological, functional and absolute) obsolescence, with economic obsolescence, partly in response to the notion of being 'due an upgrade', also featuring significantly. We also identify in this paper the concept of a secondary phone, a recently replaced phone that holds a different function for the user than their primary phone but is still valued and intentionally retained by the user, and which, we conclude, should be accounted for in any reverse logistics strategy. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Enhancing user acceptance of mandated mobile health information systems: the ePOC (electronic point-of-care project) experience.

    Science.gov (United States)

    Burgess, Lois; Sargent, Jason

    2007-01-01

    From a clinical perspective, the use of mobile technologies, such as Personal Digital Assistants (PDAs) within hospital environments is not new. A paradigm shift however is underway towards the acceptance and utility of these systems within mobile-based healthcare environments. Introducing new technologies and associated work practices has intrinsic risks which must be addressed. This paper contends that intervening to address user concerns as they arise throughout the system development lifecycle will lead to greater levels of user acceptance, while ultimately enhancing the deliverability of a system that provides a best fit with end user needs. It is envisaged this research will lead to the development of a formalised user acceptance framework based on an agile approach to user acceptance measurement. The results of an ongoing study of user perceptions towards a mandated electronic point-of-care information system in the Northern Illawarra Ambulatory Care Team (TACT) are presented.

  19. Impact of Gate Dielectric in Carrier Mobility in Low Temperature Chalcogenide Thin Film Transistors for Flexible Electronics

    KAUST Repository

    Salas-Villasenor, A. L.

    2010-06-29

    Cadmium sulfide thin film transistors were demonstrated as the n-type device for use in flexible electronics. CdS thin films were deposited by chemical bath deposition (70° C) on either 100 nm HfO2 or SiO2 as the gate dielectrics. Common gate transistors with channel lengths of 40-100 μm were fabricated with source and drain aluminum top contacts defined using a shadow mask process. No thermal annealing was performed throughout the device process. X-ray diffraction results clearly show the hexagonal crystalline phase of CdS. The electrical performance of HfO 2 /CdS -based thin film transistors shows a field effect mobility and threshold voltage of 25 cm2 V-1 s-1 and 2 V, respectively. Improvement in carrier mobility is associated with better nucleation and growth of CdS films deposited on HfO2. © 2010 The Electrochemical Society.

  20. 78 FR 32689 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Science.gov (United States)

    2013-05-31

    ... Trade Commission has received a complaint entitled Certain Portable Electronic Communications Devices... International Trade Commission (USITC): http://edis.usitc.gov . \\3\\ Electronic Document Information System (EDIS... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE...

  1. Low-noise AlGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor recessed by electron cyclotron resonance plasma etching

    CERN Document Server

    Lee, J H; Lee, C W; Yoon, H S; Park, B S; Park, C S

    1999-01-01

    GaAs pseudomorphic high electron mobility transistor recessed by electron cyclotron resonance (ECR) plasma etching have been investigated. We used a BCl sub 3 /SF sub 6 gas mixture to implement the gate recess process. We obtained a uniformity of the threshold voltage to within 50 mV in 3-inch wafers. The GaAs PHEMTs with a 0.2-mu m gate length recessed by the ECR plasma exhibited a minimum noise figure (NF sub m sub i sub n) as low as 0.26 dB with an associated gain (G sub a) of 13 dB at 12 GHz. At 18 GHz, the NF sub m sub i sub n was 0.47 dB with a Ga of 11.66 dB. These results suggest that the ECR plasma etching process reported here is suitable as a manufacturing process for gate recess of a GaAs PHEMT.

  2. Enhanced Electron Mobility in Nonplanar Tensile Strained Si Epitaxially Grown on SixGe1-xNanowires.

    Science.gov (United States)

    Wen, Feng; Tutuc, Emanuel

    2018-01-10

    We report the growth and characterization of epitaxial, coherently strained Si x Ge 1-x -Si core-shell nanowire heterostructure through vapor-liquid-solid growth mechanism for the Si x Ge 1-x core, followed by an in situ ultrahigh-vacuum chemical vapor deposition for the Si shell. Raman spectra acquired from individual nanowire reveal the Si-Si, Si-Ge, and Ge-Ge modes of the Si x Ge 1-x core and the Si-Si mode of the shell. Because of the compressive (tensile) strain induced by lattice mismatch, the core (shell) Raman modes are blue (red) shifted compared to those of unstrained bare Si x Ge 1-x (Si) nanowires, in good agreement with values calculated using continuum elasticity model coupled with lattice dynamic theory. A large tensile strain of up to 2.3% is achieved in the Si shell, which is expected to provide quantum confinement for electrons due to a positive core-to-shell conduction band offset. We demonstrate n-type metal-oxide-semiconductor field-effect transistors using Si x Ge 1-x -Si core-shell nanowires as channel and observe a 40% enhancement of the average electron mobility compared to control devices using Si nanowires due to an increased electron mobility in the tensile-strained Si shell.

  3. Characterising thermal resistances and capacitances of GaN high-electron-mobility transistors through dynamic electrothermal measurements

    DEFF Research Database (Denmark)

    Wei, Wei; Mikkelsen, Jan H.; Jensen, Ole Kiel

    2014-01-01

    This study presents a method to characterise thermal resistances and capacitances of GaN high-electron-mobility transistors (HEMTs) through dynamic electrothermal measurements. A measured relation between RF gain and the channel temperature (Tc) is formed and used for indirect measurements...... method ensures that trapping effects have insignificant impact on the measurements of Tc responses, which makes this method suitable for GaN HEMT characterisation. The applicability of this method is demonstrated by characterising thermal resistances and capacitances of a CREE CGH40006P GaN HEMT....

  4. What Clinical Information Is Valuable to Doctors Using Mobile Electronic Medical Records and When?

    Science.gov (United States)

    Kim, Junetae; Lee, Yura; Lim, Sanghee; Kim, Jeong Hoon; Lee, Byungtae; Lee, Jae-Ho

    2017-10-18

    There has been a lack of understanding on what types of specific clinical information are most valuable for doctors to access through mobile-based electronic medical records (m-EMRs) and when they access such information. Furthermore, it has not been clearly discussed why the value of such information is high. The goal of this study was to investigate the types of clinical information that are most valuable to doctors to access through an m-EMR and when such information is accessed. Since 2010, an m-EMR has been used in a tertiary hospital in Seoul, South Korea. The usage logs of the m-EMR by doctors were gathered from March to December 2015. Descriptive analyses were conducted to explore the overall usage patterns of the m-EMR. To assess the value of the clinical information provided, the usage patterns of both the m-EMR and a hospital information system (HIS) were compared on an hourly basis. The peak usage times of the m-EMR were defined as continuous intervals having normalized usage values that are greater than 0.5. The usage logs were processed as an indicator representing specific clinical information using factor analysis. Random intercept logistic regression was used to explore the type of clinical information that is frequently accessed during the peak usage times. A total of 524,929 usage logs from 653 doctors (229 professors, 161 fellows, and 263 residents; mean age: 37.55 years; males: 415 [63.6%]) were analyzed. The highest average number of m-EMR usage logs (897) was by medical residents, whereas the lowest (292) was by surgical residents. The usage amount for three menus, namely inpatient list (47,096), lab results (38,508), and investigation list (25,336), accounted for 60.1% of the peak time usage. The HIS was used most frequently during regular hours (9:00 AM to 5:00 PM). The peak usage time of the m-EMR was early in the morning (6:00 AM to 10:00 AM), and the use of the m-EMR from early evening (5:00 PM) to midnight was higher than during regular

  5. Study of the enhancement-mode AlGaN/GaN high electron mobility transistor with split floating gates

    Science.gov (United States)

    Wang, Hui; Wang, Ning; Jiang, Ling-Li; Zhao, Hai-Yue; Lin, Xin-Peng; Yu, Hong-Yu

    2017-11-01

    In this work, the charge storage based split floating gates (FGs) enhancement mode (E-mode) AlGaN/GaN high electron mobility transistors (HEMTs) are studied. The simulation results reveal that under certain density of two dimensional electron gas, the variation tendency of the threshold voltage (Vth) with the variation of the blocking dielectric thickness depends on the FG charge density. It is found that when the length sum and isolating spacing sum of the FGs both remain unchanged, the Vth shall decrease with the increasing FGs number but maintaining the device as E-mode. It is also reported that for the FGs HEMT, the failure of a FG will lead to the decrease of Vth as well as the increase of drain current, and the failure probability can be improved significantly with the increase of FGs number.

  6. Real-Time Monitoring of School Absenteeism to Enhance Disease Surveillance: A Pilot Study of a Mobile Electronic Reporting System

    Science.gov (United States)

    Lawpoolsri, Saranath; Khamsiriwatchara, Amnat; Liulark, Wongwat; Taweeseneepitch, Komchaluch; Sangvichean, Aumnuyphan; Thongprarong, Wiraporn; Kaewkungwal, Jaranit

    2014-01-01

    Background School absenteeism is a common source of data used in syndromic surveillance, which can eventually be used for early outbreak detection. However, the absenteeism reporting system in most schools, especially in developing countries, relies on a paper-based method that limits its use for disease surveillance or outbreak detection. Objective The objective of this study was to develop an electronic real-time reporting system on school absenteeism for syndromic surveillance. Methods An electronic (Web-based) school absenteeism reporting system was developed to embed it within the normal routine process of absenteeism reporting. This electronic system allowed teachers to update students' attendance status via mobile tablets. The data from all classes and schools were then automatically sent to a centralized database for further analysis and presentation, and for monitoring temporal and spatial patterns of absent students. In addition, the system also had a disease investigation module, which provided a link between absenteeism data from schools and local health centers, to investigate causes of fever among sick students. Results The electronic school absenteeism reporting system was implemented in 7 primary schools in Bangkok, Thailand, with total participation of approximately 5000 students. During May-October 2012 (first semester), the percentage of absentees varied between 1% and 10%. The peak of school absenteeism (sick leave) was observed between July and September 2012, which coincided with the peak of dengue cases in children aged 6-12 years being reported to the disease surveillance system. Conclusions The timeliness of a reporting system is a critical function in any surveillance system. Web-based application and mobile technology can potentially enhance the use of school absenteeism data for syndromic surveillance and outbreak detection. This study presents the factors that determine the implementation success of this reporting system. PMID:25099501

  7. Real-time monitoring of school absenteeism to enhance disease surveillance: a pilot study of a mobile electronic reporting system.

    Science.gov (United States)

    Lawpoolsri, Saranath; Khamsiriwatchara, Amnat; Liulark, Wongwat; Taweeseneepitch, Komchaluch; Sangvichean, Aumnuyphan; Thongprarong, Wiraporn; Kaewkungwal, Jaranit; Singhasivanon, Pratap

    2014-05-12

    School absenteeism is a common source of data used in syndromic surveillance, which can eventually be used for early outbreak detection. However, the absenteeism reporting system in most schools, especially in developing countries, relies on a paper-based method that limits its use for disease surveillance or outbreak detection. The objective of this study was to develop an electronic real-time reporting system on school absenteeism for syndromic surveillance. An electronic (Web-based) school absenteeism reporting system was developed to embed it within the normal routine process of absenteeism reporting. This electronic system allowed teachers to update students' attendance status via mobile tablets. The data from all classes and schools were then automatically sent to a centralized database for further analysis and presentation, and for monitoring temporal and spatial patterns of absent students. In addition, the system also had a disease investigation module, which provided a link between absenteeism data from schools and local health centers, to investigate causes of fever among sick students. The electronic school absenteeism reporting system was implemented in 7 primary schools in Bangkok, Thailand, with total participation of approximately 5000 students. During May-October 2012 (first semester), the percentage of absentees varied between 1% and 10%. The peak of school absenteeism (sick leave) was observed between July and September 2012, which coincided with the peak of dengue cases in children aged 6-12 years being reported to the disease surveillance system. The timeliness of a reporting system is a critical function in any surveillance system. Web-based application and mobile technology can potentially enhance the use of school absenteeism data for syndromic surveillance and outbreak detection. This study presents the factors that determine the implementation success of this reporting system.

  8. Recycling-oriented characterization of plastic frames and printed circuit boards from mobile phones by electronic and chemical imaging.

    Science.gov (United States)

    Palmieri, Roberta; Bonifazi, Giuseppe; Serranti, Silvia

    2014-11-01

    This study characterizes the composition of plastic frames and printed circuit boards from end-of-life mobile phones. This knowledge may help define an optimal processing strategy for using these items as potential raw materials. Correct handling of such a waste is essential for its further "sustainable" recovery, especially to maximize the extraction of base, rare and precious metals, minimizing the environmental impact of the entire process chain. A combination of electronic and chemical imaging techniques was thus examined, applied and critically evaluated in order to optimize the processing, through the identification and the topological assessment of the materials of interest and their quantitative distribution. To reach this goal, end-of-life mobile phone derived wastes have been systematically characterized adopting both "traditional" (e.g. scanning electronic microscopy combined with microanalysis and Raman spectroscopy) and innovative (e.g. hyperspectral imaging in short wave infrared field) techniques, with reference to frames and printed circuit boards. Results showed as the combination of both the approaches (i.e. traditional and classical) could dramatically improve recycling strategies set up, as well as final products recovery. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Electric field dependence of the electron mobility in bulk wurtzite ZnO

    Indian Academy of Sciences (India)

    Theory. The low-field mobility models are best understood by starting with the modelling approach of Caughey and Thomas (1967), μ0 = μmin + μmax − μmin. 1 + (N/C)α ,. (1) where C and α are fitting parameters, ..... ship of Scientific Research at King Saud University, Saudi. Arabia, for funding this work. The author also ...

  10. Tuning the Electronic Properties, Effective Mass and Carrier Mobility of MoS2 Monolayer by Strain Engineering: First-Principle Calculations

    Science.gov (United States)

    Phuc, Huynh V.; Hieu, Nguyen N.; Hoi, Bui D.; Hieu, Nguyen V.; Thu, Tran V.; Hung, Nguyen M.; Ilyasov, Victor V.; Poklonski, Nikolai A.; Nguyen, Chuong V.

    2018-01-01

    In this paper, we studied the electronic properties, effective masses, and carrier mobility of monolayer MoS_2 using density functional theory calculations. The carrier mobility was considered by means of ab initio calculations using the Boltzmann transport equation coupled with deformation potential theory. The effects of mechanical biaxial strain on the electronic properties, effective mass, and carrier mobility of monolayer MoS_2 were also investigated. It is demonstrated that the electronic properties, such as band structure and density of state, of monolayer MoS_2 are very sensitive to biaxial strain, leading to a direct-indirect transition in semiconductor monolayer MoS_2. Moreover, we found that the carrier mobility and effective mass can be enhanced significantly by biaxial strain and by lowering temperature. The electron mobility increases over 12 times with a biaxial strain of 10%, while the carrier mobility gradually decreases with increasing temperature. These results are very useful for the future nanotechnology, and they make monolayer MoS_2 a promising candidate for application in nanoelectronic and optoelectronic devices.

  11. PKI-based secure mobile access to electronic health services and data.

    Science.gov (United States)

    Kambourakis, G; Maglogiannis, I; Rouskas, A

    2005-01-01

    Recent research works examine the potential employment of public-key cryptography schemes in e-health environments. In such systems, where a Public Key Infrastructure (PKI) is established beforehand, Attribute Certificates (ACs) and public key enabled protocols like TLS, can provide the appropriate mechanisms to effectively support authentication, authorization and confidentiality services. In other words, mutual trust and secure communications between all the stakeholders, namely physicians, patients and e-health service providers, can be successfully established and maintained. Furthermore, as the recently introduced mobile devices with access to computer-based patient record systems are expanding, the need of physicians and nurses to interact increasingly with such systems arises. Considering public key infrastructure requirements for mobile online health networks, this paper discusses the potential use of Attribute Certificates (ACs) in an anticipated trust model. Typical trust interactions among doctors, patients and e-health providers are presented, indicating that resourceful security mechanisms and trust control can be obtained and implemented. The application of attribute certificates to support medical mobile service provision along with the utilization of the de-facto TLS protocol to offer competent confidentiality and authorization services is also presented and evaluated through experimentation, using both the 802.11 WLAN and General Packet Radio Service (GPRS) networks.

  12. O3 Layers via Spray Pyrolysis at Low Temperatures and Their Application in High Electron Mobility Transistors

    KAUST Repository

    Isakov, Ivan

    2017-04-06

    The growth mechanism of indium oxide (InO) layers processed via spray pyrolysis of an aqueous precursor solution in the temperature range of 100-300 °C and the impact on their electron transporting properties are studied. Analysis of the droplet impingement sites on the substrate\\'s surface as a function of its temperature reveals that Leidenfrost effect dominated boiling plays a crucial role in the growth of smooth, continuous, and highly crystalline InO layers via a vapor phase-like process. By careful optimization of the precursor formulation, deposition conditions, and choice of substrate, this effect is exploited and ultrathin and exceptionally smooth layers of InO are grown over large area substrates at temperatures as low as 252 °C. Thin-film transistors (TFTs) fabricated using these optimized InO layers exhibit superior electron transport characteristics with the electron mobility reaching up to 40 cm V s, a value amongst the highest reported to date for solution-processed InO TFTs. The present work contributes enormously to the basic understanding of spray pyrolysis and highlights its tremendous potential for large-volume manufacturing of high-performance metal oxide thin-film transistor electronics.

  13. Investigation of surface related leakage current in AlGaN/GaN High Electron Mobility Transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kaushik, J.K., E-mail: janeshkaushik@sspl.drdo.in [Solid State Physics Laboratory, Delhi 110054 (India); Balakrishnan, V.R.; Mongia, D.; Kumar, U.; Dayal, S. [Solid State Physics Laboratory, Delhi 110054 (India); Panwar, B.S. [Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016 (India); Muralidharan, R. [Indian Institute of Science, Bengaluru, Karnataka 560012 (India)

    2016-08-01

    This paper reports the study of surface-related mechanisms to explain the high reverse leakage current observed in the in-house fabricated Si{sub 3}N{sub 4} passivated AlGaN/GaN High Electron Mobility Transistors. We propose that the Si{sub 3}N{sub 4}/AlGaN interface in the un-gated regions provides an additional leakage path between the gate and source/drain and may constitute a large component of reverse current. This surface related leakage component of current exhibits both temperature and electric field dependence and its Arrhenius behavior has been experimentally verified using Conductance Deep Level Transient Spectroscopy and temperature dependent reverse leakage current measurements. A thin interfacial amorphous semiconductor layer formed due to inter diffusion at Si{sub 3}N{sub 4}/AlGaN interface has been presumed as the source for this surface related leakage. We, therefore, conclude that optimum Si{sub 3}N{sub 4} deposition conditions and careful surface preparation prior to passivation can limit the extent of surface leakage and can thus vastly improve the device performance. - Highlights: • Enhanced leakage in AlGaN/GaN High Electron Mobility Transistors after passivation • Experimental evidence of the presence of extrinsic traps at Si{sub 3}N{sub 4}/AlGaN interface • Electron hopping in shallower extended defects and band tail traps at the interface. • Reduction in current collapse due to the virtual gate inhibition by this conduction • However, limitation on the operating voltages due to decrease in breakdown voltage.

  14. White dwarf stars exceeding the Chandrasekhar mass limit

    Science.gov (United States)

    Tomaschitz, Roman

    2018-01-01

    The effect of nonlinear ultra-relativistic electron dispersion on the mass-radius relation of high-mass white dwarfs is studied. The dispersion is described by a permeability tensor in the Dirac equation, generated by the ionized high-density stellar matter, which constitutes the neutralizing background of the nearly degenerate electron plasma. The electron dispersion results in a stable mass-radius relation for high-mass white dwarfs, in contrast to a mass limit in the case of vacuum permeabilities. In the ultra-relativistic regime, the dispersion relation is a power law whose amplitude and scaling exponent is inferred from mass and radius estimates of two high-mass white dwarfs, Sirius B and LHS 4033. Evidence for the existence of super-Chandrasekhar mass white dwarfs is provided by several Type Ia supernovae (e.g., SN 2013cv, SN 2003fg, SN 2007if and SN 2009dc), whose mass ejecta exceed the Chandrasekhar limit by up to a factor of two. The dispersive mass-radius relation is used to estimate the radii, central densities, Fermi temperatures, bulk and compression moduli and sound velocities of their white dwarf progenitors.

  15. Enhancing Electron Mobility at the LaAlO 3 /SrTiO 3 Interface by Surface Control

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yanwu; Bell, Christopher; Hikita, Yasuyuki; Harashima, Satoshi; Hwang, Harold Y.

    2013-07-15

    Mobility of electrons confined at the LaAlO3/SrTiO3 interface is significantly enhanced by surface control using surface charges and adsorbates, reaching a low temperature value more than 20 000 cm2 V-1s-1. A uniform trend that mobility increases with decreasing sheet carrier density is observed.

  16. The impact of alloy cluster scattering on low-temperature mobility of 2D electron gas in Zn1-xMgxO/ZnO heterostructures

    Directory of Open Access Journals (Sweden)

    Hongyan Chen

    2017-06-01

    Full Text Available The influence of alloy cluster scattering on the electron transport properties in undoped Zn1-xMgxO/ZnO heterostructures was studied theoretically. Alloy cluster scattering is treated as an elastic scattering occurring between MgZnO clusters and electrons. The electron energies and wave functions are obtained to calculate the scattering rates of two-dimensional electron gas (2DEG by solving the Schrödinger and Poisson equations self-consistently. The total low-temperature mobility is then calculated by using Matthiessen’s rule. It is found that the composition fluctuation of the Zn1-xMgxO barrier affects the mobility of electrons confined in the ZnO well via alloy cluster scattering. The electron mobility limited by alloy cluster scattering decreases with Mg composition fluctuation increased from 0.01 to 0.05. Furthermore, alloy cluster scattering is one of the dominant scattering mechanisms at low temperature. When alloy cluster scattering is taken into consideration, the simulated results are in better agreement with the experimental values for lower mobility samples with higher Mg composition. This work is useful for designing Zn1-xMgxO/ZnO heterostructure devices.

  17. Assessment of toxicity potential of metallic elements in discarded electronics: a case study of mobile phones in China.

    Science.gov (United States)

    Wu, B Y; Chan, Y C; Middendorf, A; Gu, X; Zhong, H W

    2008-01-01

    The electronic waste (e-waste) is increasingly flooding Asia, especially China. E-waste could precipitate a growing volume of toxic input to the local environment if it was not handed properly. This makes the evaluation of environmental impact from electronics an essentially important task for the life cycle assessment (LCA) and the end-of-life management of electronic products. This study presented a quantitative investigation on the environmental performance of typical electronics. Two types of disposed mobile phones (MPs), as a representative of consumer electronics, were evaluated in terms of toxicity potential indicator (TPI) with an assumption of worst-case scenario. It is found that the composition and the percentages of constituents in MPs are similar. More than 20 metallic elements make up 35 wt.%-40 wt.% of the total weight, of which 12 elements are identified to be highly hazardous and 12 are less harmful. With the TPI technique, the environmental performance of Pb is attributed to be 20.8 mg(-1). The total TPIs of metallic elements in the old and new type MP is 255,403 and 127,639 units, respectively, which is equivalent to the effect of releasing 6.14 and 12.28 g Pb into the environment. The average TPI of the old and new type MP is 4.1 and 4.5 mg(-1), respectively, which suggests a similar eco-efficiency per unit mass. The new model of MP is more eco-effective than the old one, which is not due to a reduction in the type of hazardous elements, but rather due to a significant miniaturization of the package with less weight. A single MP can have a considerable toxicity to the environment as referred to Pb, which suggests a major concern for the environmental impact of the total e-waste with a huge quantity and a heavy mass in China.

  18. Enhanced electron mobility at the two-dimensional metallic surface of BaSnO3 electric-double-layer transistor at low temperatures

    Science.gov (United States)

    Fujiwara, Kohei; Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi

    2017-05-01

    Wide-bandgap oxides exhibiting high electron mobility hold promise for the development of useful electronic and optoelectronic devices as well as for basic research on two-dimensional electron transport phenomena. A perovskite-type tin oxide, BaSnO3, is currently one of such targets owing to distinctly high mobility at room temperature. The challenge to overcome towards the use of BaSnO3 thin films in applications is suppression of dislocation scattering, which is one of the dominant scattering origins for electron transport. Here, we show that the mobility of the BaSnO3 electric-double-layer transistor reaches 300 cm2 V-1 s-1 at 50 K. The improved mobility indicates that charged dislocation scattering is effectively screened by electrostatically doped high-density charge carriers. We also observed metallic conduction persisting down to 2 K, which is attributed to the transition to the degenerate semiconductor. The experimental verification of bulk-level mobility at the densely accumulated surface sheds more light on the importance of suppression of dislocation scattering by interface engineering in doped BaSnO3 thin films for transparent electrode applications.

  19. Electron small polarons and their mobility in iron (oxyhydr)oxide nanoparticles

    DEFF Research Database (Denmark)

    Katz, Jordan E; Zhang, Xiaoyi; Attenkofer, Klaus

    2012-01-01

    calculations, we observed the formation of reduced and structurally distorted metal sites consistent with small polarons. Comparisons between different phases (hematite, maghemite, and ferrihydrite) revealed that short-range structural topology, not long-range order, dominates the electron-hopping rate....

  20. In-situ transmission electron microscopy : on moving dislocations and mobile grain boundaries

    NARCIS (Netherlands)

    De Hosson, J. T. M.; Soer, W.

    This paper delineates the possibilities of utilizing in situ transmission electron microscopy to unravel dislocation-g rain boundary interactions. In situ nanoindentation experiments have been conducted in TEM on ultrafine-grained Al and Al-Mg films with varying Mg contents. The observed propagation

  1. Fabrication and characterization of V-gate AlGaN/GaN high-electron-mobility transistors

    Science.gov (United States)

    Zhang, Kai; Cao, Meng-Yi; Chen, Yong-He; Yang, Li-Yuan; Wang, Chong; Ma, Xiao-Hua; Hao, Yue

    2013-05-01

    V-gate GaN high-electron-mobility transistors (HEMTs) are fabricated and investigated systematically. A V-shaped recess geometry is obtained using an improved Si3N4 recess etching technology. Compared with standard HEMTs, the fabricated V-gate HEMTs exhibit a 17% higher peak extrinsic transconductance due to a narrowed gate foot. Moreover, both the gate leakage and current dispersion are dramatically suppressed simultaneously, although a slight degradation of frequency response is observed. Based on a two-dimensional electric field simulation using Silvaco “ATLAS" for both standard HEMTs and V-gate HEMTs, the relaxation in peak electric field at the gate edge is identified as the predominant factor leading to the superior performance of V-gate HEMTs.

  2. Enhanced plasma wave detection of terahertz radiation using multiple high electron-mobility transistors connected in series

    KAUST Repository

    Elkhatib, Tamer A.

    2010-02-01

    We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of 10-7 W/Hz0.5. The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel. © 2010 IEEE.

  3. Analysis of the damage threshold of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    Science.gov (United States)

    Xi, Xiao-Wen; Chai, Chang-Chun; Liu, Yang; Yang, Yin-Tang; Fan, Qing-Yang; Shi, Chun-Lei

    2016-08-01

    An electromagnetic pulse (EMP)-induced damage model based on the internal damage mechanism of the GaAs pseudomorphic high electron mobility transistor (PHEMT) is established in this paper. With this model, the relationships among the damage power, damage energy, pulse width and signal amplitude are investigated. Simulation results show that the pulse width index from the damage power formula obtained here is higher than that from the empirical formula due to the hotspot transferring in the damage process of the device. It is observed that the damage energy is not a constant, which decreases with the signal amplitude increasing, and then changes little when the signal amplitude reaches up to a certain level. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  4. An AlN/Al{sub 0.85}Ga{sub 0.15}N high electron mobility transistor

    Energy Technology Data Exchange (ETDEWEB)

    Baca, Albert G.; Armstrong, Andrew M.; Allerman, Andrew A.; Douglas, Erica A.; Sanchez, Carlos A.; King, Michael P.; Coltrin, Michael E.; Fortune, Torben R.; Kaplar, Robert J. [Sandia National Laboratories, PO Box 5800, Albuquerque, New Mexico 87185-1085 (United States)

    2016-07-18

    An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al{sub 0.85}Ga{sub 0.15}N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high I{sub on}/I{sub off} current ratio greater than 10{sup 7} and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.

  5. Detection of lead ions with AlGaAs/InGaAs pseudomorphic high electron mobility transistor

    Science.gov (United States)

    Jiqiang, Niu; Yang, Zhang; Min, Guan; Chengyan, Wang; Lijie, Cui; Qiumin, Yang; Yiyang, Li; Yiping, Zeng

    2016-11-01

    Lead poisoning is a serious environmental concern, which is a health threat. Existing technologies always have some drawbacks, which restrict their application ranges, such as real time monitoring. To solve this problem, glutathione was functionalized on the Au-coated gate area of the pseudomorphic high electron mobility transistor (pHEMT) to detect trace amounts of Pb2+. The positive charge of lead ions will cause a positive potential on the Au gate of the pHEMT sensor, which will increase the current between the source and the drain. The response range for Pb2+ detection has been determined in the concentrations from 0.1 pmol/L to 10 pmol/L. To our knowledge, this is currently the best result for detecting lead ions. Project supported by the National Natural Science Foundation of China (Nos. 61204012, 61274049, 61376058), the Beijing Natural Science Foundation (Nos. 4142053, 4132070), and the Beijing Nova Program (Nos. 2010B056, xxhz201503).

  6. Enhancement-Mode AIGaN/GaN High Electron Mobility Transistors Using a Nano-Channel Arrayy Structure

    Institute of Scientific and Technical Information of China (English)

    LIU Sheng-Hou; Cheng P. Wen; QIN Hua; ZHANG Bao-Shun; CAI Yong; GONG Ru-Min; WANG Jin-Yan; ZENG Chun-Hong; SHI Wen-Hua; FENG Zhi-Hong; WANG Jing-Jing; YIN Jia-Yun

    2011-01-01

    A nano-channel array (NCA) structure is applied to realize enhancement-mode (E-mode) A1GaN/GaN high electron mobility transistors (HEMTs). The fabricated NCA-HEMT,consisting of 1000 channels connected in parallel with a channel width of 64 nm,shows a threshold voltage of 0.15 V and a subthreshold slope of 78mY/dec,compared to -3.92 V and 99mV/dec for a conventional HEMT (C-HEMT),respectively.Both the NCA-HEMT and C-HEMT show similar gate leakage current,indicating no significant degradation in gate leakage characteristics for the NCA-HEMT.The surrounding-field effect and relieved polarization contribute to the very large positive threshold voltage shift,while the work function difference makes it positive.

  7. Analyzing Glycopeptide Isomers by Combining Differential Mobility Spectrometry with Electron- and Collision-Based Tandem Mass Spectrometry

    Science.gov (United States)

    Campbell, J. Larry; Baba, Takashi; Liu, Chang; Lane, Catherine S.; Le Blanc, J. C. Yves; Hager, James W.

    2017-07-01

    Differential mobility spectrometry (DMS) has been employed to separate isomeric species in several studies. Under the right conditions, factors such as separation voltage, temperature, the presence of chemical modifiers, and residence time can combine to provide unique signal channels for isomeric species. In this study, we examined a set of glycopeptide isomers, MUC5AC-3 and MUC5AC-13, which bear an N-acetyl-galactosamine (GalNAc) group on either threonine-3 or threonine-13. When analyzed as a mixture, the resulting MS and MS/MS spectra yield fragmentation patterns that cannot discern these convolved species. However, when DMS is implemented during the analysis of this mixture, two features emerge in the DMS ionogram representing the two glycopeptide isomers. In addition, by locking in DMS parameters at each feature, we could observe several low intensity CID fragments that contain the GalNAc functionality-specific amino acid residues - identifying the DMS separation of each isomer without standards. Besides conventional CID MS/MS, we also implemented electron-capture dissociation (ECD) after DMS separation, and clearly resolved both isomers with this fragmentation method, as well. The electron energy used in these ECD experiments could be tuned to obtain maximum sequence coverage for these glycopeptides; this was critical as these ions were present as doubly protonated species, which are much more difficult to fragment efficiently via electron-transfer dissociation (ETD). Overall, the combination of DMS with electron- or collision-based MS/MS methods provided enhanced separation and sequence coverage for these glycopeptide isomers.

  8. Compact muon source with electron accelerator for a mobile muSR facility

    Energy Technology Data Exchange (ETDEWEB)

    Nagamine, K., E-mail: kanetada.nagamine@ucr.ed [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Muon Science Laboratory, IMSS, KEK, Oho, Tsukuba, Ibaraki 305-0801 (Japan); Atomic Physics Laboratory, RIKEN, Wako, Saitama 351-0191 (Japan); Miyadera, H.; Jason, A. [AOT-ABS, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Seki, R. [Department of Physics, State University of California, Northridge, CA 91330-8268 (United States)

    2009-04-15

    In order to increase accessibility to the muSR spectroscopy for people in various fields of science and engineering, a conceptual design study was made to realize a compact and inexpensive muon source by using 300 MeV electron microtron and a large-acceptance muon-capture. Advanced radiography imaging with muon spin probes will become possible for bio-medical studies, inspection of re-enforced architectures, etc.

  9. Thermal Investigation of Three-Dimensional GaN-on-SiC High Electron Mobility Transistors

    Science.gov (United States)

    2017-07-01

    region of these devices. One barrier for improving the thermal design of these devices is the multi-domain simulation problem of coupling electron...transport and carrier statistics, phonon transport and populations, and ultimately full-wave electromagnetic solvers. A predictive simulation...temperature profile for operating 3D GaN-on-SiC HEMTs and improved computational efficiency with parallel computing. Task 4 - Electromagnetic Thermal

  10. A hybrid simulation technique for electrothermal studies of two-dimensional GaN-on-SiC high electron mobility transistors

    Science.gov (United States)

    Hao, Qing; Zhao, Hongbo; Xiao, Yue

    2017-05-01

    In this work, a hybrid simulation technique is introduced for the electrothermal study of a two-dimensional GaN-on-SiC high electron mobility transistor. Detailed electron and phonon transport is considered by coupled electron and phonon Monte Carlo simulations in the transistor region. For regions away from the transistor, the conventional Fourier's law is used for thermal analysis to minimize the computational load. This hybrid simulation strategy can incorporate the physical phenomena over multiple length scales, including phonon generation by hot electrons in the conduction channel, frequency-dependent phonon transport in the transistor region, and heat transfer across the whole macroscale device.

  11. Growth optimization and characterization of high mobility two-dimensional electron systems in AlAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Dasgupta, Shivaji

    2009-02-15

    In this work two-dimensional electron systems (2DESs) based on AlAs/AlGaAs heterostructures doped with Si are investigated. The electrons are confined in AlAs quantum wells (QWs) sandwiched between AlGaAs buffers. Analytical calculations and simulations for AlAs QWs are presented in the first chapter. The results show a cross-over width, above which the wide (001)-oriented QWs show double valley occupancy and wide (110)-oriented QWs show single valley occupancy. We solve the Schroedinger equation analytically for anisotropic masses. The solution shows the orientation dependence of the elliptical cyclotron orbit due to the anisotropic mass. We also present an introduction to the Landau level crossings based on g{sup *}m{sup *} product. In the next chapter, we present experimental results for the double-valley (001)-oriented AlAs QWs. We present the different structures of the deep AlAs QWs along with the low temperature magnetotransport data for these QWs. Thereafter, we present the results on shallow AlAs QWs. We achieved a mobility of 4.2 x 10{sup 5} cm{sup 2}/Vs at 330 mK for the deep backside doped AlAs QW. For the shallow QWs, we achieved a mobility of2.3 x 10{sup 5} cm{sup 2}/Vs at 330 mK, for a density of 2.9 x 10{sup 11} cm{sup -2}. From the magneto-transport data, we see evidence of the double-valley occupation for the (001)-oriented AlAs wide QWs. In the next chapter, we present experimental results for the single-valley (110)-oriented AlAs QWs. We deduced the donor binding energy and the doping efficiency for this facet from a doping series of double-sided doped QWs. Thereafter, we designed different structures for the (110)-oriented AlAs QWs, which we present along with their respective low temperature magneto-transport data. We measured one of the double-sided doped AlAs QWs at very high magnetic fields and low temperatures, down to 60 mK. At the end of the chapter, we present a spike feature observed in the magneto-transport data of these QWs. This

  12. 14 CFR 29.1505 - Never-exceed speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Never-exceed speed. 29.1505 Section 29.1505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS....1505 Never-exceed speed. (a) The never-exceed speed, V NE, must be established so that it is— (1) Not...

  13. 14 CFR 27.1505 - Never-exceed speed.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Never-exceed speed. 27.1505 Section 27.1505 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS... Never-exceed speed. (a) The never-exceed speed, VNE, must be established so that it is— (1) Not less...

  14. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-03-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  15. Damage effect and mechanism of the GaAs high electron mobility transistor induced by high power microwave

    Science.gov (United States)

    Yang, Liu; Chang-Chun, Chai; Yin-Tang, Yang; Jing, Sun; Zhi-Peng, Li

    2016-04-01

    In this paper, we present the damage effect and mechanism of high power microwave (HPM) on AlGaAs/GaAs pseudomorphic high-electron-mobility transistor (pHEMT) of low-noise amplifier (LNA). A detailed investigation is carried out by simulation and experiment study. A two-dimensional electro-thermal model of the typical GaAs pHEMT induced by HPM is established in this paper. The simulation result reveals that avalanche breakdown, intrinsic excitation, and thermal breakdown all contribute to damage process. Heat accumulation occurs during the positive half cycle and the cylinder under the gate near the source side is most susceptible to burn-out. Experiment is carried out by injecting high power microwave into GaAs pHEMT LNA samples. It is found that the damage to LNA is because of the burn-out at first stage pHEMT. The interiors of the damaged samples are observed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). Experimental results accord well with the simulation of our model. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (Grant No. 2015-0214.XY.K).

  16. A CMOS application-specified-integrated-circuit for 40 GHz high-electron-mobility-transistors automatic biasing

    Science.gov (United States)

    De Matteis, M.; De Blasi, M.; Vallicelli, E. A.; Zannoni, M.; Gervasi, M.; Bau, A.; Passerini, A.; Baschirotto, A.

    2017-02-01

    This paper presents the design and the experimental results of a CMOS Automatic Control System (ACS) for the biasing of High-Electron-Mobility-Transistors (HEMT). The ACS is the first low-power mixed-signal Application-Specified-Integrated-Circuit (ASIC) able to automatically set and regulate the operating point of an off-chip 6 HEMT Low-Noise-Amplifiers (LNAs), hence it composes a two-chip system (the ACS+LNAs) to be used in the Large Scale Polarization Explorer (LSPE) stratospheric balloon for Cosmic Microwave Background (CMB) signal observation. The hereby presented ACS ASIC provides a reliable instrumentation for gradual and very stable LNAs characterization, switching-on, and operating point (<4 mV accuracy). Moreover, it simplifies the electronic instrumentation needed for biasing the LNAs, since it replaces several off-the-shelf and digital programmable device components. The ASIC prototype has been implemented in a CMOS 0.35 μ m technology (12 mm2 area occupancy). It operates at 4 kHz clock frequency. The power consumption of one-channel ASIC (biasing one LNA) is 3.6 mW, whereas 30 mW are consumed by a single LNA device.

  17. Simulation of zincblende AlGaN/GaN high electron mobility transistors for normally-off operation

    Science.gov (United States)

    Grady, R.; Bayram, C.

    2017-07-01

    In this work we investigate design parameters enabling normally-off operation of zincblende (ZB-) phase Al X Ga(1-X)N/GaN high electron mobility transistors (HEMTs) via Synopsys Sentaurus Technology Computer Aided Design (TCAD). As ZB-phase III-nitrides are polarization-free, the 2D electron gas (2DEG) channel at the Al X Ga(1-X)N/GaN heterojunction is formed through intentional δ-doping part of the Al X Ga(1-X)N barrier layer. The impact of each of the design parameters (i.e. Al-content and thickness of Al X Ga(1-X)N barrier; δ-doping location (within the Al X Ga(1-X)N barrier), δ-doped Al X Ga(1-X)N layer thickness and its doping amount; gate metal) are studied in detail and design trade-offs are reported. We show that work function of the gate metal impacts normally-off behavior and turn-on voltage considerably. Our results suggest that Al-content of 35% or less in the Al X Ga(1-X)N barrier results in a normally-off behavior whereas Al X Ga(1-X)N barrier thickness is effective in controlling the turn-on voltage. Overall, we provide design guidelines in controlling the normally-on/-off operation, threshold voltage, and 2DEG density in ZB-phase AlGaN/GaN HEMT technology.

  18. Characterization of a high performance ultra-thin heat pipe cooling module for mobile hand held electronic devices

    Science.gov (United States)

    Ahamed, Mohammad Shahed; Saito, Yuji; Mashiko, Koichi; Mochizuki, Masataka

    2017-11-01

    In recent years, heat pipes have been widely used in various hand held mobile electronic devices such as smart phones, tablet PCs, digital cameras. With the development of technology these devices have different user friendly features and applications; which require very high clock speeds of the processor. In general, a high clock speed generates a lot of heat, which needs to be spreaded or removed to eliminate the hot spot on the processor surface. However, it is a challenging task to achieve proper cooling of such electronic devices mentioned above because of their confined spaces and concentrated heat sources. Regarding this challenge, we introduced an ultra-thin heat pipe; this heat pipe consists of a special fiber wick structure named as "Center Fiber Wick" which can provide sufficient vapor space on the both sides of the wick structure. We also developed a cooling module that uses this kind of ultra-thin heat pipe to eliminate the hot spot issue. This cooling module consists of an ultra-thin heat pipe and a metal plate. By changing the width, the flattened thickness and the effective length of the ultra-thin heat pipe, several experiments have been conducted to characterize the thermal properties of the developed cooling module. In addition, other experiments were also conducted to determine the effects of changes in the number of heat pipes in a single module. Characterization and comparison of the module have also been conducted both experimentally and theoretically.

  19. Low-temperature carrier dynamics in high-mobility organic transistors of alkylated dinaphtho-thienothiophene as investigated by electron spin resonance

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, Yutaro; Tanaka, Hisaaki, E-mail: htanaka@nuap.nagoya-u.ac.jp; Kuroda, Shin-ichi [Department of Applied Physics, Nagoya University, Chikusa, Nagoya 464-8603 (Japan); Shimoi, Yukihiro [Nanosystem Research Institute (NRI), National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Takimiya, Kazuo [Emergent Molecular Function Research Group, RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198 (Japan)

    2014-07-21

    Charge carriers in high-mobility organic thin-film transistors of alkylated dinaphtho-thienothiophene (C{sub 10}-DNTT) have been directly observed by field-induced electron spin resonance (FI-ESR) down to 4 K. FI-ESR spectra of π-electron hole carriers of C{sub 10}-DNTT exhibited clear anisotropy, indicating a highly organized end-on molecular orientation at the device interface. The intra-grain and inter-grain carrier motion were probed by the motional narrowing effect of the ESR spectra. The intra-grain motion was clearly observed even at 4 K, showing intrinsically high mobility of C{sub 10}-DNTT crystallites. On the other hand, significantly low activation energy of ∼10 meV for inter-grain carrier hopping, compared with pristine DNTT, was observed, which shows that the alkyl substitution drastically enhances the carrier mobility of DNTT system.

  20. Comparison of Surface Passivation Films for Reduction of Current Collapse in AlGaN/GaN High Electron Mobility Transistors (HEMTs)

    National Research Council Canada - National Science Library

    Fitch, R

    2002-01-01

    Three different passivation layers (SiN(x), MgO, and Sc2O3) were examined for their effectiveness in mitigating surface-state-induced current collapse in AlGaN/GaN high electron mobility transistors (HEMTs...

  1. Personalized Fall Risk Assessment Tool by using the Data Treasure contained in Mobile Electronic Patient Records.

    Science.gov (United States)

    Eryilmaz, Elif; Ahrndt, Sebastian; Fähndrich, Johannes; Albayrak, Sahin

    2014-01-01

    This work presents a novel approach for combining multiple Electronic Patient Records (EPRs) to a self-learning fall risk assessment tool. This tool is used by a new type of home-visiting nurses to track the fall risk of their patients. In order to provide personalized healthcare for elderly people, we combine multiple EPRs using an agent-based architecture, where each patient is represented by an associated agent. The patient agents are enabled to negotiate about possible fallrisk indicators recognized in the specific patient population under care. We use distributed information fusion and opinion aggregation techniques to elaborate new fall-risk indicators and in consequence to adapt the fall risk assessment tool.

  2. Nanopatterning of mobile lipid monolayers on electron-beam-sculpted Teflon AF surfaces.

    Science.gov (United States)

    Shaali, Mehrnaz; Lara-Avila, Samuel; Dommersnes, Paul; Ainla, Alar; Kubatkin, Sergey; Jesorka, Aldo

    2015-02-24

    Direct electron-beam lithography is used to fabricate nanostructured Teflon AF surfaces, which are utilized to pattern surface-supported monolayer phospholipid films with 50 nm lateral feature size. In comparison with unexposed Teflon AF coatings, e-beam-irradiated areas show reduced surface tension and surface potential. For phospholipid monolayer spreading experiments, these areas can be designed to function as barriers that enclose unexposed areas of nanometer dimensions and confine the lipid film within. We show that the effectiveness of the barrier is defined by pattern geometry and radiation dose. This surface preparation technique represents an efficient, yet simple, nanopatterning strategy supporting studies of lipid monolayer behavior in ultraconfined spaces. The generated structures are useful for imaging studies of biomimetic membranes and other specialized surface applications requiring spatially controlled formation of self-assembled, molecularly thin films on optically transparent patterned polymer surfaces with very low autofluorescence.

  3. Effect of crystal orientation on conductivity and electron mobility in single-crystal alumina

    Science.gov (United States)

    Will, Fritz G.; Delorenzi, Horst G.; Janora, Kevin H.

    1992-01-01

    The electrical conductivity of high-purity, single-crystal alumina is determined parallel to and perpendicular to the c-axis. The mean conductivity of four samples of each orientation is a factor 3.3 higher parallel to the c-axis than perpendicular to it. The conductivity as a function of temperature is attributed to extrinsic electron conduction at temperatures from 400 to 900 C, and intrinsic semiconduction at temperatures from 900 to 1300 C. In the high-temperature regime, the slope on all eight specimens is 4.7 +/- 0.1 eV. Hence, the thermal bandgap at O K is 9.4 +/- 0.2 eV.

  4. Role of dislocations and carrier concentration in limiting the electron mobility of InN films grown by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Tangi, Malleswararao; De, Arpan; Shivaprasad, S. M.

    2018-01-01

    We report the molecular beam epitaxy growth of device quality InN films on GaN epilayer and nano-wall network (NWN) templates deposited on c-sapphire by varying the film thickness up to 1 μm. The careful experiments are directed towards obtaining high mobility InN layers having a low band gap with improved crystal quality. The dislocation density is quantified by using high resolution X-ray diffraction rocking curve broadening values of symmetric and asymmetric reflections, respectively. We observe that the dislocation density of the InN films grown on GaN NWN is less than that of the films grown on the GaN epilayer. This is attributed to the nanoepitaxial lateral overlayer growth (ELOG) process, where the presence of voids at the interface of InN/GaN NWN prevents the propagation of dislocation lines into the InN epilayers, thereby causing less defects in the overgrown InN films. Thus, this new adaptation of the nano-ELOG growth process enables us to prepare InN layers with high electron mobility. The obtained electron mobility of 2121 cm2/Vs for 1 μm thick InN/GaN NWN is comparable with the literature values of similar thickness InN films. Furthermore, in order to understand the reasons that limit electron mobility, the charge neutrality condition is employed to study the variation of electron mobility as a function of dislocation density and carrier concentration. Overall, this study provides a route to attaining improved crystal quality and electronic properties of InN films.

  5. Mobile Device-Based Electronic Data Capture System Used in a Clinical Randomized Controlled Trial: Advantages and Challenges.

    Science.gov (United States)

    Zhang, Jing; Sun, Lei; Liu, Yu; Wang, Hongyi; Sun, Ningling; Zhang, Puhong

    2017-03-08

    Electronic data capture (EDC) systems have been widely used in clinical research, but mobile device-based electronic data capture (mEDC) system has not been well evaluated. The aim of our study was to evaluate the feasibility, advantages, and challenges of mEDC in data collection, project management, and telemonitoring in a randomized controlled trial (RCT). We developed an mEDC to support an RCT called "Telmisartan and Hydrochlorothiazide Antihypertensive Treatment (THAT)" study, which was a multicenter, double-blinded, RCT, with the purpose of comparing the efficacy of telmisartan and hydrochlorothiazide (HCTZ) monotherapy in high-sodium-intake patients with mild to moderate hypertension during a 60 days follow-up. Semistructured interviews were conducted during and after the trial to evaluate the feasibility, advantage, and challenge of mEDC. Nvivo version 9.0 (QSR International) was used to analyze records of interviews, and a thematic framework method was used to obtain outcomes. The mEDC was successfully used to support the data collection and project management in all the 14 study hospitals. A total of 1333 patients were recruited with support of mEDC, of whom 1037 successfully completed all 4 visits. Across all visits, the average time needed for 141 questions per patient was 53 min, which were acceptable to both doctors and patients. All the interviewees, including 24 doctors, 53 patients, 1 clinical research associate (CRA), 1 project manager (PM), and 1 data manager (DM), expressed their satisfaction to nearly all the functions of the innovative mEDC in randomization, data collection, project management, quality control, and remote monitoring in real time. The average satisfaction score was 9.2 (scale, 0-10). The biggest challenge came from the stability of the mobile or Wi-Fi signal although it was not a problem in THAT study. The innovative mEDC has many merits and is well acceptable in supporting data collection and project management in a timely

  6. First-principles hybrid functional study of the electronic structure and charge carrier mobility in perovskite CH3NH3SnI3

    Science.gov (United States)

    Wu, Li-Juan; Zhao, Yu-Qing; Chen, Chang-Wen; Wang, Lin-Zhi; Liu, Biao; Cai, Meng-Qiu

    2016-10-01

    We calculate the electronic properties and carrier mobility of perovskite CH3NH3SnI3 as a solar cell absorber by using the hybrid functional method. The calculated result shows that the electron and hole mobilities have anisotropies with a large magnitude of 1.4 × 104 cm2·V-1·s-1 along the y direction. In view of the huge difference between hole and electron mobilities, the perovskite CH3NH3SnI3 can be considered as a p-type semiconductor. We also discover a relationship between the effective mass anisotropy and electronic occupation anisotropy. The above results can provide reliable guidance for its experimental applications in electronics and optoelectronics. Project supported by the National Natural Science Foundation of China (Grant No. 51172067), the Hunan Provincial Natural Science Fund for Distinguished Young Scholars, China (Grant No. 13JJ1013), the Specialized Research Fund for the Doctoral Program of Higher Education, China (Grant No. 20130161110036), and the New Century Excellent Talents in University, China (Grant No. NCET-12-0171.D).

  7. Optimization design on breakdown voltage of AlGaN/GaN high-electron mobility transistor

    Science.gov (United States)

    Yang, Liu; Changchun, Chai; Chunlei, Shi; Qingyang, Fan; Yuqian, Liu

    2016-12-01

    Simulations are carried out to explore the possibility of achieving high breakdown voltage of GaN HEMT (high-electron mobility transistor). GaN cap layers with gradual increase in the doping concentration from 2 × 1016 to 5 × 1019 cm-3 of N-type and P-type cap are investigated, respectively. Simulation results show that HEMT with P-doped GaN cap layer shows more potential to achieve higher breakdown voltage than N-doped GaN cap layer under the same doping concentration. This is because the ionized net negative space charges in P-GaN cap layer could modulate the surface electric field which makes more contribution to RESURF effect. Furthermore, a novel GaN/AlGaN/GaN HEMT with P-doped GaN buried layer in GaN buffer between gate and drain electrode is proposed. It shows enhanced performance. The breakdown voltage of the proposed structure is 640 V which is increased by 12% in comparison to UID (un-intentionally doped) GaN/AlGaN/GaN HEMT. We calculated and analyzed the distribution of electrons' density. It is found that the depleted region is wider and electric field maximum value is induced at the left edge of buried layer. So the novel structure with P-doped GaN buried layer embedded in GaN buffer has the better improving characteristics of the power devices. Project supported by the National Basic Research Program of China (No. 2014CB339900) and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (No. 2015-0214.XY.K).

  8. Multicharacterization approach for studying InAl(Ga)N/Al(Ga)N/GaN heterostructures for high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Naresh-Kumar, G., E-mail: naresh.gunasekar@strath.ac.uk; Trager-Cowan, C. [Dept of Physics, SUPA, University of Strathclyde, Glasgow G4 0NG (United Kingdom); Vilalta-Clemente, A.; Morales, M.; Ruterana, P. [CIMAP UMR 6252 CNRS-ENSICAEN-CEA-UCBN 14050 Caen Cedex (France); Pandey, S.; Cavallini, A.; Cavalcoli, D. [Dipartimento di Fisica Astronomia, Università di Bologna, 40127 Bologna (Italy); Skuridina, D.; Vogt, P.; Kneissl, M. [Institute of Solid State Physics, Technical University Berlin, 10623 Berlin (Germany); Behmenburg, H.; Giesen, C.; Heuken, M. [AIXTRON SE, Kaiserstr. 98, 52134 Herzogenrath (Germany); Gamarra, P.; Di Forte-Poisson, M. A. [Thales Research and Technology, III-V Lab, 91460 Marcoussis (France); Patriarche, G. [LPN, Route de Nozay, 91460 Marcoussis (France); Vickridge, I. [Institut des NanoSciences, Université Pierre et Marie Curie, 75015 Paris (France)

    2014-12-15

    We report on our multi–pronged approach to understand the structural and electrical properties of an InAl(Ga)N(33nm barrier)/Al(Ga)N(1nm interlayer)/GaN(3μm)/ AlN(100nm)/Al{sub 2}O{sub 3} high electron mobility transistor (HEMT) heterostructure grown by metal organic vapor phase epitaxy (MOVPE). In particular we reveal and discuss the role of unintentional Ga incorporation in the barrier and also in the interlayer. The observation of unintentional Ga incorporation by using energy dispersive X–ray spectroscopy analysis in a scanning transmission electron microscope is supported with results obtained for samples with a range of AlN interlayer thicknesses grown under both the showerhead as well as the horizontal type MOVPE reactors. Poisson–Schrödinger simulations show that for high Ga incorporation in the Al(Ga)N interlayer, an additional triangular well with very small depth may be exhibited in parallel to the main 2–DEG channel. The presence of this additional channel may cause parasitic conduction and severe issues in device characteristics and processing. Producing a HEMT structure with InAlGaN as the barrier and AlGaN as the interlayer with appropriate alloy composition may be a possible route to optimization, as it might be difficult to avoid Ga incorporation while continuously depositing the layers using the MOVPE growth method. Our present work shows the necessity of a multicharacterization approach to correlate structural and electrical properties to understand device structures and their performance.

  9. Multicharacterization approach for studying InAl(GaN/Al(GaN/GaN heterostructures for high electron mobility transistors

    Directory of Open Access Journals (Sweden)

    G. Naresh-Kumar

    2014-12-01

    Full Text Available We report on our multi–pronged approach to understand the structural and electrical properties of an InAl(GaN(33nm barrier/Al(GaN(1nm interlayer/GaN(3μm/ AlN(100nm/Al2O3 high electron mobility transistor (HEMT heterostructure grown by metal organic vapor phase epitaxy (MOVPE. In particular we reveal and discuss the role of unintentional Ga incorporation in the barrier and also in the interlayer. The observation of unintentional Ga incorporation by using energy dispersive X–ray spectroscopy analysis in a scanning transmission electron microscope is supported with results obtained for samples with a range of AlN interlayer thicknesses grown under both the showerhead as well as the horizontal type MOVPE reactors. Poisson–Schrödinger simulations show that for high Ga incorporation in the Al(GaN interlayer, an additional triangular well with very small depth may be exhibited in parallel to the main 2–DEG channel. The presence of this additional channel may cause parasitic conduction and severe issues in device characteristics and processing. Producing a HEMT structure with InAlGaN as the barrier and AlGaN as the interlayer with appropriate alloy composition may be a possible route to optimization, as it might be difficult to avoid Ga incorporation while continuously depositing the layers using the MOVPE growth method. Our present work shows the necessity of a multicharacterization approach to correlate structural and electrical properties to understand device structures and their performance.

  10. Accuracy of pharmacy benefit manager medication formularies in an electronic health record system and the Epocrates mobile application.

    Science.gov (United States)

    Andrus, Miranda R; Forrester, Jeanne B; Germain, Kenda E; Eiland, Lea S

    2015-04-01

    Physicians commonly use formulary medication coverage information generated by electronic heath records (EHRs) and the Epocrates mobile drug database application when making medication selection decisions. Nonformulary selections may lead to higher out-of-pocket patient costs and nonadherence with prescribed regimens. Nonformulary selections also contribute to higher overall health plan spending. However, the accuracy of these systems compared with actual insurance coverage is not known.  To assess the accuracy of formulary status icons generated by an EHR system and the Epocrates mobile application for patients with Alabama Medicaid and Blue Cross Blue Shield of Alabama (BCBS), the primary insurance providers in the state of Alabama. Patients of all ages who had a chart review performed at the outpatient family medicine or pediatric clinics at the University of Alabama at Birmingham Huntsville Medical Regional Campus from May to October 2013 were included in this retrospective analysis. Patients who were not insured by either Alabama Medicaid or BCBS were excluded. Patients who did not have new medications added at the time of the visit were also excluded. For each medication prescribed, the formulary status provided in the EHR system and Epocrates was compared with the actual Medicaid and BCBS formularies published online, and the accuracy of the 2 databases was determined.  A total of 1,529 medication records were analyzed. The EHR and Epocrates provided accurate formulary information for 93.1% and 89.4% of medications, respectively. Formulary information generated by the EHR was 96.3% accurate for Medicaid patients and 80.1% accurate for BCBS patients. Epocrates was 88.2% accurate for Medicaid patients and 94.4% accurate for BCBS patients. A total of 936 medication records from the pediatric clinic were analyzed, and the majority of these patients (88.4%) had Medicaid insurance. In this population, the EHR was more accurate (96.9%) than Epocrates (86.6%). Of

  11. Tablet computers with mobile electronic medical records enhance clinical routine and promote bedside time: a controlled prospective crossover study.

    Science.gov (United States)

    Fleischmann, Robert; Duhm, Julian; Hupperts, Hagen; Brandt, Stephan A

    2015-03-01

    Demographic changes require physicians to deliver needed services with fewer resources. Neurology as an interdisciplinary domain involves complex diagnostic procedures and time-consuming data handling. Tablet PCs might streamline clinical workflow through mobile access to patient data. This study examined the impact of tablets running an electronic medical record on ward round performance. We hypothesised that tablet use should reduce ward round time and decrease the time needed to check medical records thereby increasing physicians' bedside availability. Nine resident neurologists participated in a controlled prospective crossover trial over 14 weeks. In the experimental condition, tablets were used in addition to the established medical record. In the control condition, physicians used established systems only. The combined primary outcome measure included changes in total ward round time and relative time shifts between associated work processes. The secondary outcome measure was physicians' time required to check a medical record vs. physicians' bedside time. There was a significant main effect on the primary outcome measure (p = 0.01). Tablet use accelerated preparing (p = 0.004) and post-processing (p Time for conducting ward rounds was unaffected (p = 0.19). Checking medical records was faster with tablets (p = 0.001) increasing physicians' bedside time (p time savings during preparing and post-processing of ward rounds. It was further associated with time savings during checking medical data and an increase in physicians' bedside time. Tablets may facilitate clinical data handling and promote workflow.

  12. Damage effect and mechanism of the GaAs pseudomorphic high electron mobility transistor induced by the electromagnetic pulse

    Science.gov (United States)

    Xiao-Wen, Xi; Chang-Chun, Chai; Gang, Zhao; Yin-Tang, Yang; Xin-Hai, Yu; Yang, Liu

    2016-04-01

    The damage effect and mechanism of the electromagnetic pulse (EMP) on the GaAs pseudomorphic high electron mobility transistor (PHEMT) are investigated in this paper. By using the device simulation software, the distributions and variations of the electric field, the current density and the temperature are analyzed. The simulation results show that there are three physical effects, i.e., the forward-biased effect of the gate Schottky junction, the avalanche breakdown, and the thermal breakdown of the barrier layer, which influence the device current in the damage process. It is found that the damage position of the device changes with the amplitude of the step voltage pulse. The damage appears under the gate near the drain when the amplitude of the pulse is low, and it also occurs under the gate near the source when the amplitude is sufficiently high, which is consistent with the experimental results. Project supported by the National Basic Research Program of China (Grant No. 2014CB339900), and the Open Fund of Key Laboratory of Complex Electromagnetic Environment Science and Technology, China Academy of Engineering Physics (CAEP) (Grant No. 2015-0214.XY.K).

  13. Viscosity-dependent drain current noise of AlGaN/GaN high electron mobility transistor in polar liquids

    Energy Technology Data Exchange (ETDEWEB)

    Fang, J. Y.; Hsu, C. P.; Kang, Y. W.; Fang, K. C.; Kao, W. L.; Yao, D. J.; Chen, C. C.; Li, S. S.; Yeh, J. A.; Wang, Y. L. [Institute of Nanoengineering and Microsystems, National Tsing Hua University, Hsinchu 300, Taiwan (China); Lee, G. Y.; Chyi, J. I. [Department of Electrical engineering, National Central University, Jhongli City, Taoyuan County 32001, Taiwan (China); Hsu, C. H. [Division of Medical Engineering, National Health Research Institutes, MiaoLi, Taiwan (China); Huang, Y. F. [Department of Biomedical Engineering and Environmental Science, National Tsing Hua University, Hsinchu 300, Taiwan (China); Ren, F. [Department of Chemical Engineering, University of Florida, Gainesville, Florida 32611 (United States)

    2013-11-28

    The drain current fluctuation of ungated AlGaN/GaN high electron mobility transistors (HEMTs) measured in different fluids at a drain-source voltage of 0.5 V was investigated. The HEMTs with metal on the gate region showed good current stability in deionized water, while a large fluctuation in drain current was observed for HEMTs without gate metal. The fluctuation in drain current for the HEMTs without gate metal was observed and calculated as standard deviation from a real-time measurement in air, deionized water, ethanol, dimethyl sulfoxide, ethylene glycol, 1,2-butanediol, and glycerol. At room temperature, the fluctuation in drain current for the HEMTs without gate metal was found to be relevant to the dipole moment and the viscosity of the liquids. A liquid with a larger viscosity showed a smaller fluctuation in drain current. The viscosity-dependent fluctuation of the drain current was ascribed to the Brownian motions of the liquid molecules, which induced a variation in the surface dipole of the gate region. This study uncovers the causes of the fluctuation in drain current of HEMTs in fluids. The results show that the AlGaN/GaN HEMTs may be used as sensors to measure the viscosity of liquids within a certain range of viscosity.

  14. An Investigation of Carbon-Doping-Induced Current Collapse in GaN-on-Si High Electron Mobility Transistors

    Directory of Open Access Journals (Sweden)

    An-Jye Tzou

    2016-06-01

    Full Text Available This paper reports the successful fabrication of a GaN-on-Si high electron mobility transistor (HEMT with a 1702 V breakdown voltage (BV and low current collapse. The strain and threading dislocation density were well-controlled by 100 pairs of AlN/GaN superlattice buffer layers. Relative to the carbon-doped GaN spacer layer, we grew the AlGaN back barrier layer at a high temperature, resulting in a low carbon-doping concentration. The high-bandgap AlGaN provided an effective barrier for blocking leakage from the channel to substrate, leading to a BV comparable to the ordinary carbon-doped GaN HEMTs. In addition, the AlGaN back barrier showed a low dispersion of transiently pulsed ID under substrate bias, implying that the buffer traps were effectively suppressed. Therefore, we obtained a low-dynamic on-resistance with this AlGaN back barrier. These two approaches of high BV with low current collapse improved the device performance, yielding a device that is reliable in power device applications.

  15. How we developed eForms: an electronic form and data capture tool to support assessment in mobile medical education.

    Science.gov (United States)

    Mooney, Jane S; Cappelli, Tim; Byrne-Davis, Lucie; Lumsden, Colin J

    2014-12-01

    Mobile learning technologies are being introduced and adopted by an increasing number of medical schools. Following the implementation of these devices, institutions are tasked with the challenge of their integration into curriculum delivery and presented with the opportunity to facilitate data collection from large student cohorts. Since 2011, Manchester Medical School (MMS) has undertaken the largest deployment of iPads within UK Higher Education. Working towards the more efficient collation of students' compulsory workplace-based assessment data led us to evaluate how existing information management software could replace previously paper-based systems. Following an evaluation of six, and a trial of one, commercially available packages, the existing software solutions were found to be inflexible and unfit for purpose. This resulted in the development of a new digital solution that addressed the limitations of the previous system. "University of Manchester (UoM) eForms" consists of an app and a web-based administration system that respectively permit high volume data collection and management. UoM eForms has now replaced the preceding paper-based and electronic systems within MMS for workplace-based assessment administration, due to the improved usability and dynamicity built into its interface and infrastructure. This new system has found many further useful applications, including research data collection, feedback, placement evaluations, quality assurance and interview marking.

  16. Quantitative Analysis Of User Interfaces For Large Electronic Home Appliances And Mobile Devices Based On Lifestyle Categorization Of Older Users.

    Science.gov (United States)

    Shin, Wonkyoung; Park, Minyong

    2017-01-01

    Background/Study Context: The increasing longevity and health of older users as well as aging populations has created the need to develop senior-oriented product interfaces. This study aims to find user interface (UI) priorities according to older user groups based on their lifestyle and develop quality of UI (QUI) models for large electronic home appliances and mobile products. A segmentation table designed to show how older users can be categorized was created through a review of the literature to survey 252 subjects with a questionnaire. Factor analysis was performed to extract six preliminary lifestyle factors, which were then used for subsequent cluster analysis. The analysis resulted in four groups. Cross-analysis was carried out to investigate which characteristics were included in the groups. Analysis of variance was then applied to investigate the differences in the UI priorities among the user groups for various electronic devices. Finally, QUI models were developed and applied to those electronic devices. Differences in UI priorities were found according to the four lifestyles ("money-oriented," "innovation-oriented," "stability- and simplicity-oriented," and "innovation- and intellectual-oriented"). Twelve QUI models were developed for four different lifestyle groups associated with different products. Three washers and three smartphones were used as an example for testing the QUI models. The UI differences of the older user groups by the segmentation in this study using several key (i.e., demographic, socioeconomic, and physical-cognitive) variables are distinct from earlier studies made by a single variable. The differences in responses clearly indicate the benefits of integrating various factors of older users, rather than single variable, in order to design and develop more innovative and better consumer products in the future. The results of this study showed that older users with a potentially high buying power in the future are likely to have

  17. 44 CFR 206.67 - Requirement when limitation is exceeded.

    Science.gov (United States)

    2010-10-01

    ... 44 Emergency Management and Assistance 1 2010-10-01 2010-10-01 false Requirement when limitation is exceeded. 206.67 Section 206.67 Emergency Management and Assistance FEDERAL EMERGENCY MANAGEMENT... Assistance § 206.67 Requirement when limitation is exceeded. Whenever the limitation described in § 206.66 is...

  18. A mobile app for securely capturing and transferring clinical images to the electronic health record: description and preliminary usability study.

    Science.gov (United States)

    Landman, Adam; Emani, Srinivas; Carlile, Narath; Rosenthal, David I; Semakov, Simon; Pallin, Daniel J; Poon, Eric G

    2015-01-02

    Photographs are important tools to record, track, and communicate clinical findings. Mobile devices with high-resolution cameras are now ubiquitous, giving clinicians the opportunity to capture and share images from the bedside. However, secure and efficient ways to manage and share digital images are lacking. The aim of this study is to describe the implementation of a secure application for capturing and storing clinical images in the electronic health record (EHR), and to describe initial user experiences. We developed CliniCam, a secure Apple iOS (iPhone, iPad) application that allows for user authentication, patient selection, image capture, image annotation, and storage of images as a Portable Document Format (PDF) file in the EHR. We leveraged our organization's enterprise service-oriented architecture to transmit the image file from CliniCam to our enterprise clinical data repository. There is no permanent storage of protected health information on the mobile device. CliniCam also required connection to our organization's secure WiFi network. Resident physicians from emergency medicine, internal medicine, and dermatology used CliniCam in clinical practice for one month. They were then asked to complete a survey on their experience. We analyzed the survey results using descriptive statistics. Twenty-eight physicians participated and 19/28 (68%) completed the survey. Of the respondents who used CliniCam, 89% found it useful or very useful for clinical practice and easy to use, and wanted to continue using the app. Respondents provided constructive feedback on location of the photos in the EHR, preferring to have photos embedded in (or linked to) clinical notes instead of storing them as separate PDFs within the EHR. Some users experienced difficulty with WiFi connectivity which was addressed by enhancing CliniCam to check for connectivity on launch. CliniCam was implemented successfully and found to be easy to use and useful for clinical practice. CliniCam is

  19. Enhancement of terahertz coupling efficiency by improved antenna design in GaN/AlGaN high electron mobility transistor detectors

    Institute of Scientific and Technical Information of China (English)

    Sun Yun-Fei; Sun Jan-Dong; Zhang Xiao-Yu; Qin Hua; Zhang Bao-Shun; Wu Dong-Min

    2012-01-01

    An optimized micro-gated terahertz detector with novel triple resonant antenna is presented.The novel resonant antenna operates at room temperature and shows more than a 700% increase in photocurrent response compared to the conventional bowtie antenna.In finite-difference-time-domain simulations,we found the performance of the self-mixing GaN/AlGaN high electron mobility transistor detector is mainly dependent on the parameters Lgs (the gap between the gate and the source/drain antenna) and Lw (the gap between the source and drain antenna).With the improved triple resonant antenna,an optimized micrometer-sized AlGaN/GaN high electron mobility transistor detector can achieve a high responsivity of 9.45 × 102 V/W at a frequency of 903 GHz at room temperature.

  20. Low electron-polar optical phonon scattering as a fundamental aspect of carrier mobility in methylammonium lead halide CH3NH3PbI3 perovskites.

    Science.gov (United States)

    Filippetti, A; Mattoni, A; Caddeo, C; Saba, M I; Delugas, P

    2016-06-01

    High carrier mobility is often invoked to justify the exceptionally long diffusion length in CH3NH3PbI3 perovskites. Using a combination of an ab initio band structure and scattering models, we present clear evidence that large electrical and Hall mobilities are crucially related to the low scattering rate of carriers with polar optical phonons, which represents the dominant mobility-limiting mechanism at room temperature. With a charge-injection regime at room temperature, we obtained carrier relaxation times (τrel) of ∼10 fs, which are typical of polar inorganic semiconductors, and electrical mobilities (μ) as high as ∼60 cm(2) V(-1) s(-1) and 40 cm(2) V(-1) s(-1) for electrons and holes, respectively, which were robustly independent on the injected carrier density in the range of n ∼ 10(14) cm(-3) to 10(20) cm(-3). In the absence of a significant concentration of trapping centers, these mobilities foster diffusion lengths of ∼10 μm for the low injection density regime (n ∼ 10(15) cm(-3)), which are in agreement with recent measurements for highly pure single-crystal perovskites.

  1. WordEdge® A Career Mobility Guide to High Speed Dictionary-Based Electronic Learning and Testing

    Directory of Open Access Journals (Sweden)

    Robert Oliphant

    2009-01-01

    Full Text Available As Thomas Kuhn taught us, misery loves innovation even more than company. Small wonder our recession worriers — and who isn’t one these days, directly or indirectly? — are desperately looking for new and practical ways to increase their job mobility. Statistically considered, since most unskilled jobs are already filled, jobseekers from shrinking fields of employment are being advised to broaden their search to include entry level jobs in new high tech fields that are either stable or expanding, e.g., health care.Let’s grant that each high tech field has its own hands-on skills. But it’s also true that each field, e.g., plumbing, has its own high tech vocabulary which each candidate for employment is expected to know or learn, including correct pronunciation, very much like an aspiring restaurant server learning the complete menu by heart. Hence the desirability of acquiring preliminary mastery of an employment field’s high tech vocabulary well in ADVANCE of the first interview, not in a panicky last minute cram session. Until recently, the only way we could acquire a preliminary mastery of, say, health care terms was to take a course (inconvenient and expensive or to study a specific-field booklet (usually limited inscope. Today, however, our current partnership between print dictionaries and their electronic versions gives any job candidate quick access to an amazingly efficient learning tool for masteringa wide range of high tech vocabularies in current use. Here’s the why and how of our dictionary-based learning and testing route.

  2. Low-field electron mobility and thermoelectric power in In1-xGaxAsyP1-y lattice-matched to InP

    Science.gov (United States)

    Sutradhar, S. K.; Chattopadhyay, D.; Nag, B. R.

    1982-03-01

    Electron drift and Hall mobility, and thermoelectric power in In1-xGaxAsyP1-y, lattice-matched to InP, are calculated for different temperatures and compositions. The two-mode nature of the polar optic phonons is considered jointly with deformation-potential acoustic, piezoelectric, alloy, ionized-impurity, and electron-electron scattering. Band nonparabolicity, admixture of p functions, arbitrary degeneracy of the electron distribution, and the screening effects of free carriers on the scattering probabilities are incorporated. The Boltzmann equation is solved by an iterative method using the currently established values of the material parameters. The agreement with the available experimental data is found to be satisfactory.

  3. Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy

    DEFF Research Database (Denmark)

    Schuetz, P.; Christensen, Dennis Valbjørn; Borisov, V.

    2017-01-01

    The spinel/perovskite heterointerface γ−Al2O3/SrTiO3 hosts a two-dimensional electron system (2DES) with electron mobilities exceeding those in its all-perovskite counterpart LaAlO3/SrTiO3 by more than an order of magnitude, despite the abundance of oxygen vacancies which act as electron donors a...

  4. Direct current performance and current collapse in AlGaN/GaN insulated gate high-electron mobility transistors on Si (1 1 1) substrate with very thin SiO2 gate dielectric

    Science.gov (United States)

    Lachab, M.; Sultana, M.; Fatima, H.; Adivarahan, V.; Fareed, Q.; Khan, M. A.

    2012-12-01

    This work reports on the dc performance of AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOSHEMTs) grown on Si (1 1 1) substrate and the study of current dispersion in these devices using various widely adopted methods. The MOSHEMTs were fabricated using a very thin (4.2 nm) SiO2 film as the gate insulator and were subsequently passivated with about 30 nm thick Si3N4 layer. For devices with 2.5 µm long gates and a 4 µm drain-to-source spacing, the maximum saturation drain current density was 822 mA mm-1 at + 4 V gate bias and the peak external transconductance was ˜100 mS mm-1. Furthermore, the oxide layer successfully suppressed the drain and gate leakage currents with the subthreshold current and the gate diode current levels exceeding by more than three orders of magnitude the levels found in their Schottky gate counterparts. Capacitance-voltage and dynamic current-voltage measurements were carried out to assess the oxide quality as well as the devices’ surface properties after passivation. The efficacy of each of these characterization techniques to probe the presence of interface traps and oxide charge in the nitride-based transistors is also discussed.

  5. A high-mobility two-dimensional electron gas at the spinel/perovskite interface of γ-Al2O3/SrTiO3

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Bovet, N.; Trier, Felix

    2013-01-01

    The discovery of two-dimensional electron gases at the heterointerface between two insulating perovskite-type oxides, such as LaAlO3 and SrTiO3, provides opportunities for a new generation of all-oxide electronic devices. Key challenges remain for achieving interfacial electron mobilities much...

  6. Method to quantify the delocalization of electronic states in amorphous semiconductors and its application to assessing charge carrier mobility of p -type amorphous oxide semiconductors

    Science.gov (United States)

    de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

    2018-01-01

    Amorphous semiconductors are usually characterized by a low charge carrier mobility, essentially related to their lack of long-range order. The development of such material with higher charge carrier mobility is hence challenging. Part of the issue comes from the difficulty encountered by first-principles simulations to evaluate concepts such as the electron effective mass for disordered systems since the absence of periodicity induced by the disorder precludes the use of common concepts derived from condensed matter physics. In this paper, we propose a methodology based on first-principles simulations that partially solves this problem, by quantifying the degree of delocalization of a wave function and of the connectivity between the atomic sites within this electronic state. We validate the robustness of the proposed formalism on crystalline and molecular systems and extend the insights gained to disordered/amorphous InGaZnO4 and Si. We also explore the properties of p -type oxide semiconductor candidates recently reported to have a low effective mass in their crystalline phases [G. Hautier et al., Nat. Commun. 4, 2292 (2013), 10.1038/ncomms3292]. Although in their amorphous phase none of the candidates present a valence band with delocalization properties matching those found in the conduction band of amorphous InGaZnO4, three of the seven analyzed materials show some potential. The most promising candidate, K2Sn2O3 , is expected to possess in its amorphous phase a slightly higher hole mobility than the electron mobility in amorphous silicon.

  7. Central role of electronic temperature for photoelectron charge and spin mobilities in p{sup +}-GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Cadiz, F., E-mail: fabian.cadiz@polytechnique.edu; Paget, D.; Rowe, A. C. H. [Physique de la Matière Condensée, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Peytavit, E.; Arscott, S. [Institut d' Electronique, de Microélectronique et de Nanotechnologie (IEMN), University of Lille, CNRS, Avenue Poincaré, Cité Scientifique, 59652 Villeneuve d' Ascq (France)

    2015-03-02

    The charge and spin mobilities of minority photoelectrons in p{sup +}-GaAs are determined by monitoring the effect of an electric field on the spatial profiles of the luminescence and of its polarization. By using electric fields to increase the photoelectron temperature T{sub e} without significantly changing the hole or lattice temperatures, the charge and spin mobilities are shown to be principally dependent on T{sub e}. For T{sub e} > 70 K, both the charge and spin mobilities vary as T{sub e}{sup −1.3}, while at lower temperatures this changes to an even more rapid T{sub e}{sup −4.3} law. This finding suggests that current theoretical models based on degeneracy of majority carriers cannot fully explain the observed temperature dependence of minority carrier mobility.

  8. Electron mobility in polarization-doped Al0-0.2GaN with a low concentration near 1017 cm-3

    Science.gov (United States)

    Zhu, Mingda; Qi, Meng; Nomoto, Kazuki; Hu, Zongyang; Song, Bo; Pan, Ming; Gao, Xiang; Jena, Debdeep; Xing, Huili Grace

    2017-05-01

    In this letter, carrier transport in graded AlxGa1-xN with a polarization-induced n-type doping as low as ˜1017 cm-3 is reported. The graded AlxGa1-xN is grown by metal organic chemical vapor deposition on a sapphire substrate, and a uniform n-type doping without any intentional doping is realized by linearly varying the Al composition from 0% to 20% over a thickness of 600 nm. A compensating center concentration of ˜1017 cm-3 was also estimated. A peak mobility of 900 cm2/V.s at room temperature is extracted at an Al composition of ˜7%, which represents the highest mobility achieved in n-Al0.07GaN with a carrier concentration of ˜1017 cm-3. A comparison between experimental data and theoretical models shows that, at this low doping concentration, both dislocation scattering and alloy scattering are significant in limiting electron mobility and that a dislocation density of doping levels in GaN, a critical parameter in the design of novel power electronics taking advantage of polarization doping.

  9. Low-resistance gateless high electron mobility transistors using three-dimensional inverted pyramidal AlGaN/GaN surfaces

    Energy Technology Data Exchange (ETDEWEB)

    So, Hongyun, E-mail: hyso@stanford.edu [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Senesky, Debbie G. [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)

    2016-01-04

    In this letter, three-dimensional gateless AlGaN/GaN high electron mobility transistors (HEMTs) were demonstrated with 54% reduction in electrical resistance and 73% increase in surface area compared with conventional gateless HEMTs on planar substrates. Inverted pyramidal AlGaN/GaN surfaces were microfabricated using potassium hydroxide etched silicon with exposed (111) surfaces and metal-organic chemical vapor deposition of coherent AlGaN/GaN thin films. In addition, electrical characterization of the devices showed that a combination of series and parallel connections of the highly conductive two-dimensional electron gas along the pyramidal geometry resulted in a significant reduction in electrical resistance at both room and high temperatures (up to 300 °C). This three-dimensional HEMT architecture can be leveraged to realize low-power and reliable power electronics, as well as harsh environment sensors with increased surface area.

  10. Spin dynamics in high-mobility two-dimensional electron systems embedded in GaAs/AlGaAs quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Griesbeck, Michael

    2012-11-22

    Since many years there has been great effort to explore the spin dynamics in low-dimensional electron systems embedded in GaAs/AlGaAs based heterostructures for the purpose of quantum computation and spintronics applications. Advances in technology allow for the design of high quality and well-defined two-dimensional electron systems (2DES), which are perfectly suited for the study of the underlying physics that govern the dynamics of the electron spin system. In this work, spin dynamics in high-mobility 2DES is studied by means of the all-optical time-resolved Kerr/Faraday rotation technique. In (001)-grown 2DES, a strong in-plane spin dephasing anisotropy is studied, resulting from the interference of comparable Rashba and Dresselhaus contributions to the spin-orbit field (SOF). The dependence of this anisotropy on parameters like the confinement length of the 2DES, the sample temperature, as well as the electron density is demonstrated. Furthermore, coherent spin dynamics of an ensemble of ballistically moving electrons is studied without and within an applied weak magnetic field perpendicular to the sample plane, which forces the electrons to move on cyclotron orbits. Finally, strongly anisotropic spin dynamics is investigated in symmetric (110)-grown 2DES, using the resonant spin amplification method. Here, extremely long out-of-plane spin dephasing times can be achieved, in consequence of the special symmetry of the Dresselhaus SOF.

  11. Relative Li-ion mobility mapping in Li0.33La0.56TiO3 polycrystalline by electron backscatter diffraction and electrochemical strain microscopy

    Science.gov (United States)

    Sasano, Shun; Ishikawa, Ryo; Sugiyama, Issei; Higashi, Takuma; Kimura, Teiichi; Ikuhara, Yumi H.; Shibata, Naoya; Ikuhara, Yuichi

    2017-06-01

    Li-ion conductivity in a solid-state electrolyte has so far been measured by impedance spectroscopy. In this method, however, it is difficult to obtain microstructural information because of the absence of spatial resolution. Here, we show the relationship between the Li-ion mobility and the crystal orientation in Li0.33La0.56TiO3 polycrystalline by electrochemical strain microscopy combined with electron backscatter diffraction. On the experimentally constructed multivariable regression model, we obtained a qualitative Li-ion mobility map of sub-millimeter width with a 100 nm spatial resolution, which is impossible to achieve by only atomic force microscopy. The proposed method must be useful for identifying the Li-ion diffusion pathway in three dimensions.

  12. Demonstration of InAlN/AlGaN high electron mobility transistors with an enhanced breakdown voltage by pulsed metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xue, JunShuai, E-mail: junshuaixue@hotmail.com; Zhang, JinCheng; Hao, Yue [Key Laboratory of Wide Band Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2016-01-04

    In this work, InAlN/AlGaN heterostructures employing wider bandgap AlGaN instead of conventional GaN channel were grown on sapphire substrate by pulsed metal organic chemical vapor deposition, where the nominal Al composition in InAlN barrier and AlGaN channel were chosen to be 83% and 5%, respectively, to achieve close lattice-matched condition. An electron mobility of 511 cm{sup 2}/V s along with a sheet carrier density of 1.88 × 10{sup 13 }cm{sup −2} were revealed in the prepared heterostructures, both of which were lower compared with lattice-matched InAlN/GaN due to increased intrinsic alloy disorder scattering resulting from AlGaN channel and compressively piezoelectric polarization in barrier, respectively. While the high electron mobility transistor (HEMT) processed on these structures not only exhibited a sufficiently high drain output current density of 854 mA/mm but also demonstrated a significantly enhanced breakdown voltage of 87 V, which is twice higher than that of reported InAlN/GaN HEMT with the same device dimension, potential characteristics for high-voltage operation of GaN-based electronic devices.

  13. Médecins Sans Frontières' Clinical Guidance mobile application: analysis of a new electronic health tool.

    Science.gov (United States)

    Wright, V; Dalwai, M; Smith, R Vincent; Jemmy, J-P

    2015-12-21

    Many health care workers lack access to clinical support tools in rural and resource-limited settings. To address this gap, the Médecins Sans Frontières (MSF) Clinical Guidelines manual was converted into a static mobile health reference application (app) entitled MSF Guidance. The app's utility and growth was examined, and within 6 months of its launch 150 countries had downloaded the app, with demonstrated retention among new and existing users. With over 3500 downloads and 36 000 sessions amounting to 250 000 screen views, MSF Guidance is a new mobile health platform with widely demonstrated utility, including potential use as an epidemiological tool, where clinical conditions investigated by app users were found to correlate with geographical outbreaks. These findings show that mobile apps can be used to disseminate health information effectively.

  14. Four laser companies to exceed $1 billion revenue in 2016

    Science.gov (United States)

    Thoss, Andreas F.

    2017-02-01

    It seems very likely that for first time four companies will exceed the revenue of 1 billion in 2016. This comes along with substantial changes in the market for lasers and laser systems. The article analyzes some of the changes and looks at the individual success strategies of the major players in these markets.

  15. Optimal acquisition : Why children's language production can exceed their comprehension

    NARCIS (Netherlands)

    Hendriks, Pieterke; Hamann, Cornelia; Ruigendijk, Esther

    2015-01-01

    This paper discusses a developmental paradox, namely that children’s performance in language production sometimes exceeds their performance in language comprehension. This yields a puzzle for most theories of language acquisition. If a child produces a linguistic form correctly, this is considered

  16. Enhanced photocatalytic activity of α-Bi2O3 with high electron-hole mobility by codoping approach: A first-principles study

    Science.gov (United States)

    Li, Yujie; Yang, Fan; Yu, Ying

    2015-12-01

    To improve the photocatalytic activity of narrow-gap material Bi2O3, efforts need be made to lower the electron-hole recombination rate and widen the response range of visible light. Understanding the related mechanism is vital, which may lead to high electron-hole mobility and suitable band edge. In this paper we have studied the atomic and electronic structure of single metallic atom (Ag, Cu, Pb, Pd, Sn)-doped and nitrogen (N)-metal codoped Bi2O3 with α phase by first principles calculations. The calculation results firstly show that new impurity states appeared in band gap of α-Bi2O3 after single metal doping, especially for the doping of Cu, Ag and Pb, which showed shallow acceptor levels for α-Bi2O3. And the formation energy analysis indicates that Cu doped system was easier to be formed than other doped systems. All of those calculated properties are helpful to enhance the photocatalytic property of α-Bi2O3, which agrees well with experimental results. Interestingly, for anion atom N together with metallic atom (Ag, Cu, Pb, Pd, Sn) codoped α-Bi2O3 systems, it is found that N-2p state had impact on the electronic structure. Holes were demonstrated to be more delocalized in (Cu + N) codoped α-Bi2O3 system, which was responsible for high mobility of holes, then lowering the electron-hole recombination, and finally improving the photocatalytic performance of Bi2O3 significantly.

  17. Localization of Post-Translational Modifications in Peptide Mixtures via High-Resolution Differential Ion Mobility Separations Followed by Electron Transfer Dissociation

    Science.gov (United States)

    Baird, Matthew A.; Shvartsburg, Alexandre A.

    2016-12-01

    Precise localization of post-translational modifications (PTMs) on proteins and peptides is an outstanding challenge in proteomics. While electron transfer dissociation (ETD) has dramatically advanced PTM analyses, mixtures of localization variants that commonly coexist in cells often require prior separation. Although differential or field asymmetric waveform ion mobility spectrometry (FAIMS) achieves broad variant resolution, the need for standards to identify the features has limited the utility of approach. Here we demonstrate full a priori characterization of variant mixtures by high-resolution FAIMS coupled to ETD and the procedures to systematically extract the FAIMS spectra for all variants from such data.

  18. High Electron Mobility and Ambient Stability in Solution-Processed Perylene-Based Organic Field-Effect Transistors

    NARCIS (Netherlands)

    Piliego, Claudia; Jarzab, Dorota; Gigli, Giuseppe; Chen, Zhihua; Facchetti, Antonio; Loi, M.A.

    2009-01-01

    {Bottom-contact n-channel OFETs basedon spin-coated films of N,N'-1H,1H-perfluorobutyl dicyanoperylenediimide (PDI-FCN2) exhibit a saturation-regime mobility of 0.15 cm(2) V-1 s(-1) in vacuum and good air stability. These performances are attributed to the high crystallinity and to the edge-on

  19. Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces via charge transfer induced modulation doping

    DEFF Research Database (Denmark)

    Chen, Yunzhong; Trier, Felix; Wijnands, T.

    2015-01-01

    The discovery of two-dimensional electron gases (2DEGs) at the interface between two insulating complex oxides, such as LaAlO3 (LAO) or gamma-Al2O3 (GAO) epitaxially grown on SrTiO3 (STO), provides an opportunity for developing all-oxide electronic devices. These 2DEGs at complex oxide interfaces...... than two orders of magnitude. Our in-situ and resonant x-ray spectroscopic in addition to transmission electron microscopy results indicate that the manganite layer undergoes unambiguous electronic reconstruction and leads to modulation doping of such atomically engineered complex oxide......The discovery of two-dimensional electron gases (2DEGs) at the interface between two insulating complex oxides, such as LaAlO3 (LAO) or gamma-Al2O3 (GAO) epitaxially grown on SrTiO3 (STO), provides an opportunity for developing all-oxide electronic devices. These 2DEGs at complex oxide interfaces...

  20. Study on payments through mobile phones

    Directory of Open Access Journals (Sweden)

    Anca Ioana ANDREESCU

    2006-01-01

    Full Text Available The evolution of information and communications technology, together with the increasing use of electronic commerce, phones and mobile applications, have facilitated mobile payments to become an alternative payment method for buyers and vendors. Mobile payments offer various opportunities to business environment and became a starting point in the transition from electronic to mobile. This paper aims to analyze the present situation of the mobile payment methods and to identify the effects that mobile payment systems have on electronic commerce.

  1. 2k{sub F}-selected conductance oscillations of high-mobility two-dimensional electron gas in Corbino devices

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaoxue [International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing (China); Collaborative Innovation Center of Quantum Matter, 100871, Beijing (China); Zhu, Yuying; Yang, Changli; Lu, Li [Collaborative Innovation Center of Quantum Matter, 100871, Beijing (China); Institute of Physics, Chinese Academy of Sciences, 100190, Beijing (China); Du, Lingjie [Rice University, Houston, Texas 77251-1892 (United States); Pfeiffer, Loren; West, Kenneth [Princeton University, Princeton, New Jersey 08544 (United States); Du, Rui-Rui [International Center for Quantum Materials, School of Physics, Peking University, 100871, Beijing (China); Collaborative Innovation Center of Quantum Matter, 100871, Beijing (China); Rice University, Houston, Texas 77251-1892 (United States)

    2014-11-03

    We have observed electrical-field induced magneto-conductivity oscillations measured in Corbino samples made of a GaAs high-mobility two-dimensional electron gas, and found a consistent interpretation based on a semiclassical model of 2k{sub F}-selected orbital transitions between N and N + 1, 2, 3,…, Landau levels at respective local potentials, where k{sub F} is the Fermi wavevector. From the oscillation period, we deduce an effective mass value, which is consistent with the bare electron band mass of GaAs. In the same devices but with a vanishing electrical field and at elevated temperatures, we observed additional oscillation features, which can be attributed to cyclotron resonance by population of acoustic phonons. We thus demonstrate a method to determine the carrier effective mass and the sound velocity of host crystals by standard electrical transport.

  2. Analysis of resonant detection of terahertz radiation in high-electron mobility transistor with a nanostring/carbon nanotube as the mechanically floating gate

    Science.gov (United States)

    Leiman, V. G.; Ryzhii, M.; Satou, A.; Ryabova, N.; Ryzhii, V.; Otsuji, T.; Shur, M. S.

    2008-07-01

    We develop a device model for a resonant detector of electromagnetic radiation with a frequency in the terahertz (THz) range modulated by megahertz (MHz) or gigahertz (GHz) signals based on a micromachined high-electron mobility transistor (HEMT) with a metallized nanostring (NS) or metallic carbon nanotube (CNT) as mechanically the floating gate and analyze the detector operation. The device model describes both the NS/CNT mechanical motion and plasma effects in the HEMT two-dimensional electron channel. Using this model, we calculate the output gate alternating current and the detector responsivity as functions of the carrier (in the THz range) and modulation frequencies, which are in the THz and MHz (or GHz range), respectively. It is shown that the THz detector responsivity exhibits sharp and high maxima under the conditions of both mechanical and plasma resonances.

  3. High electron mobility thin-film transistors based on Ga{sub 2}O{sub 3} grown by atmospheric ultrasonic spray pyrolysis at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Stuart R., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk; Lin, Yen-Hung; Faber, Hendrik; Anthopoulos, Thomas D., E-mail: s.thomas09@imperial.ac.uk, E-mail: thomas.anthopoulos@imperial.ac.uk [Department of Physics, Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom); Adamopoulos, George [Department of Engineering, Engineering Building, Lancaster University, Bailrigg, Lancaster LA1 4YR (United Kingdom); Sygellou, Labrini [Institute of Chemical Engineering and High Temperature Processes (ICEHT), Foundation of Research and Technology Hellas (FORTH), Stadiou Strasse Platani, P.O. Box 1414, Patras GR-265 04 (Greece); Stratakis, Emmanuel [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), Heraklion 71003 (Greece); Materials Science and Technology Department, University, of Crete, Heraklion 71003 (Greece); Pliatsikas, Nikos; Patsalas, Panos A. [Laboratory of Applied Physics, Department of Physics, Aristotle University of Thessaloniki, Thessaloniki GR-54124 (Greece)

    2014-09-01

    We report on thin-film transistors based on Ga{sub 2}O{sub 3} films grown by ultrasonic spray pyrolysis in ambient atmosphere at 400–450 °C. The elemental, electronic, optical, morphological, structural, and electrical properties of the films and devices were investigated using a range of complementary characterisation techniques, whilst the effects of post deposition annealing at higher temperature (700 °C) were also investigated. Both as-grown and post-deposition annealed Ga{sub 2}O{sub 3} films are found to be slightly oxygen deficient, exceptionally smooth and exhibit a wide energy bandgap of ∼4.9 eV. Transistors based on as-deposited Ga{sub 2}O{sub 3} films show n-type conductivity with the maximum electron mobility of ∼2 cm{sup 2}/V s.

  4. An enzymatic biosensor based on three-dimensional ZnO nanotetrapods spatial net modified AlGaAs/GaAs high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yu [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology, Beijing 100083 (China); Bioengineering Program, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Zhang, Xiaohui; Yan, Xiaoqin; Liao, Qingliang; Wang, Zengze; Zhang, Yue, E-mail: yuezhang@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology, Beijing 100083 (China)

    2014-11-24

    We designed and constructed three dimensional (3D) zinc oxide Nanotetrapods (T-ZnOs) modified AlGaAs/GaAs high electron mobility transistors (HEMTs) for enzymatic uric acid (UA) detection. The chemical vapor deposition synthesized T-ZnOs was distributed on the gate areas of HEMTs in order to immobilize uricase and improve the sensitivity of the HEMTs. Combining with the high efficiency of enzyme immobilization by T-ZnOs and high sensitivity from HEMT, the as-constructed uricase/T-ZnOs/HEMTs biosensor showed fast response towards UA at ∼1 s, wide linear range from 0.2 nM to 0.2 mM and the low detect limit at 0.2 nM. The results point out an avenue to design electronic device as miniaturized lab-on-chip device for high sensitive and specific in biomedical and clinical diagnosis applications.

  5. Trap behaviours characterization of AlGaN/GaN high electron mobility transistors by room-temperature transient capacitance measurement

    Directory of Open Access Journals (Sweden)

    Bin Dong

    2016-09-01

    Full Text Available In this paper, the trap behaviours in AlGaN/GaN high electron mobility transistors (HEMTs are investigated using transient capacitance measurement. By measuring the transient gate capacitance variance (ΔC with different pulse height, the gate pulse induced trap behaviours in SiNX gate dielectric layer or at the SiNX/AlGaN interface is revealed. Based on the results, a model on electron traps in AlGaN/GaN HEMTs is proposed. The threshold voltage (Vth instability in AlGaN/GaN HEMTs is believed to be correlated with the presence of these traps in SiNX gate dielectric layer or at the SiNX/AlGaN interface. Furthermore, trap density before and after step-stress applied on drain electrode is quantitatively analyzed based on ΔC measurement.

  6. Suppressed carrier density for the patterned high mobility two-dimensional electron gas at γ-Al2O3/SrTiO3 heterointerfaces

    DEFF Research Database (Denmark)

    Niu, Wei; Gan, Yulin; Christensen, Dennis Valbjørn

    2017-01-01

    The two-dimensional electron gas (2DEG) at the non-isostructural interface between spinel γ-Al2O3 and perovskite SrTiO3 is featured by a record electron mobility among complex oxide interfaces in addition to a high carrier density up to the order of 1015 cm-2. Herein, we report on the patterning ...

  7. Time Exceedances for High Intensity Solar Proton Fluxes

    Science.gov (United States)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adam, James H., Jr.; Dietrich, William F.

    2011-01-01

    A model is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  8. Effect of surface passivation by SiN/SiO{sub 2} of AlGaN/GaN high-electron mobility transistors on Si substrate by deep level transient spectroscopy method

    Energy Technology Data Exchange (ETDEWEB)

    Gassoumi, Malek, E-mail: malek.gassoumi@fsm.rnu.tn; Mosbahi, Hana; Zaidi, Mohamed Ali [Universite deMonastir, Laboratoire de Micro-Optoelectroniques et Nanostructures, Faculte des Sciences de Monastir (Tunisia); Gaquiere, Christophe [Universite des Sciences et Technologies de Lille, Institut d' Electronique de Microelectronique et de Nanotechnologie IEMN, Departement hyperfrequences et Semiconducteurs (France); Maaref, Hassen [Universite deMonastir, Laboratoire de Micro-Optoelectroniques et Nanostructures, Faculte des Sciences de Monastir (Tunisia)

    2013-07-15

    Device performance and defects in AlGaN/GaN high-electron mobility transistors have been correlated. The effect of SiN/SiO{sub 2} passivation of the surface of AlGaN/GaN high-electron mobility transistors on Si substrates is reported on DC characteristics. Deep level transient spectroscopy (DLTS) measurements were performed on the device after the passivation by a (50/100 nm) SiN/SiO{sub 2} film. The DLTS spectra from these measurements showed the existence of the same electron trap on the surface of the device.

  9. Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces by charge-transfer-induced modulation doping

    NARCIS (Netherlands)

    Chen, Yunzhong; Trier, F.; Wijnands, Tom; Green, R.J.; Gauquelin, N.; Egoavil, R.; Christensen, D.V.; Koster, Gertjan; Huijben, Mark; Bovet, N.; Macke, S.; He, F.; Sutarto, R.; Andersen, N.H.; Sulpizio, J.A.; Honig, M.; Prawiroatmodjo, G.E.D.K.; Jespersen, T.S.; Linderoth, S.; Ilani, S.; Verbeeck, J.; van Tendeloo, G.; Rijnders, Augustinus J.H.M.; Sawatzky, G.A.; Pryds, N.

    2015-01-01

    Two-dimensional electron gases (2DEGs) formed at the interface of insulating complex oxides promise the development of all-oxide electronic devices. These 2DEGs involve many-body interactions that give rise to a variety of physical phenomena such as superconductivity, magnetism, tunable

  10. Ground-state phase diagram, fermionic entanglement and kinetically-induced frustration in a hybrid ladder with localized spins and mobile electrons

    Science.gov (United States)

    Carvalho, R. C. P.; Pereira, M. S. S.; de Oliveira, I. N.; Strečka, J.; Lyra, M. L.

    2017-09-01

    We introduce an exactly solvable hybrid spin-ladder model containing localized nodal Ising spins and interstitial mobile electrons, which are allowed to perform a quantum-mechanical hopping between the ladder’s legs. The quantum-mechanical hopping process induces an antiferromagnetic coupling between the ladder’s legs that competes with a direct exchange coupling of the nodal spins. The model is exactly mapped onto the Ising spin ladder with temperature-dependent two- and four-spin interactions, which is subsequently solved using the transfer-matrix technique. We report the ground-state phase diagram and compute the fermionic concurrence to characterize the quantum entanglement between the pair of interstitial mobile electrons. We further provide a detailed analysis of the local spin ordering including the pair and four-spin correlation functions around an elementary plaquette, as well as, the local ordering diagrams. It is shown that a complex sequence of distinct local orderings and frustrated correlations takes place when the model parameters drive the investigated system close to a zero-temperature triple coexistence point.

  11. AlGaN/GaN high electron mobility transistors with a low sub-threshold swing on free-standing GaN wafer

    Directory of Open Access Journals (Sweden)

    Xinke Liu

    2017-09-01

    Full Text Available This paper reported AlGaN/GaN high electron mobility transistors (HEMTs with low sub-threshold swing SS on free-standing GaN wafer. High quality AlGaN/GaN epi-layer has been grown by metal-organic chemical vapor deposition (MOCVD on free-standing GaN, small full-width hall maximum (FWHM of 42.9 arcsec for (0002 GaN XRD peaks and ultralow dislocation density (∼104-105 cm-2 were obtained. Due to these extremely high quality material properties, the fabricated AlGaN/GaN HEMTs achieve a low SS (∼60 mV/decade, low hysteresis of 54 mV, and high peak electron mobility μeff of ∼1456 cm2V-1s-1. Systematic study of materials properties and device characteristics exhibits that GaN-on-GaN AlGaN/GaN HEMTs are promising candidate for next generation high power device applications.

  12. AlGaN/GaN high electron mobility transistors with a low sub-threshold swing on free-standing GaN wafer

    Science.gov (United States)

    Liu, Xinke; Gu, Hong; Li, Kuilong; Guo, Lunchun; Zhu, Deliang; Lu, Youming; Wang, Jianfeng; Kuo, Hao-Chung; Liu, Zhihong; Liu, Wenjun; Chen, Lin; Fang, Jianping; Ang, Kah-Wee; Xu, Ke; Ao, Jin-Ping

    2017-09-01

    This paper reported AlGaN/GaN high electron mobility transistors (HEMTs) with low sub-threshold swing SS on free-standing GaN wafer. High quality AlGaN/GaN epi-layer has been grown by metal-organic chemical vapor deposition (MOCVD) on free-standing GaN, small full-width hall maximum (FWHM) of 42.9 arcsec for (0002) GaN XRD peaks and ultralow dislocation density (˜104-105 cm-2) were obtained. Due to these extremely high quality material properties, the fabricated AlGaN/GaN HEMTs achieve a low SS (˜60 mV/decade), low hysteresis of 54 mV, and high peak electron mobility μeff of ˜1456 cm2V-1s-1. Systematic study of materials properties and device characteristics exhibits that GaN-on-GaN AlGaN/GaN HEMTs are promising candidate for next generation high power device applications.

  13. I've got 99 problems but a phone ain't one: Electronic and mobile health in low and middle income countries.

    Science.gov (United States)

    Kumar, Pratap; Paton, Chris; Kirigia, Doris

    2016-10-01

    Mobile technology is very prevalent in Kenya-mobile phone penetration is at 88% and mobile data subscriptions form 99% of all internet subscriptions. While there is great potential for such ubiquitous technology to revolutionise access and quality of healthcare in low-resource settings, there have been few successes at scale. Implementations of electronic health (e-Health) and mobile health (m-Health) technologies in countries like Kenya are yet to tackle human resource constraints or the political, ethical and financial considerations of such technologies. We outline recent innovations that could improve access and quality while considering the costs of healthcare. One is an attempt to create a scalable clinical decision support system by engaging a global network of specialist doctors and reversing some of the damaging effects of medical brain drain. The other efficiently extracts digital information from paper-based records using low-cost and locally produced tools such as rubber stamps to improve adherence to clinical practice guidelines. By bringing down the costs of remote consultations and clinical audit, respectively, these projects offer the potential for clinics in resource-limited settings to deliver high-quality care. This paper makes a case for continued and increased investment in social enterprises that bridge academia, public and private sectors to deliver sustainable and scalable e-Health and m-Health solutions. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  14. Electronic structure calculations of mercury mobilization from mineral phases and photocatalytic removal from water and the atmosphere.

    Science.gov (United States)

    Da Pieve, Fabiana; Stankowski, Martin; Hogan, Conor

    2014-09-15

    Mercury is a hazardous environmental pollutant mobilized from natural sources, and anthropogenically contaminated and disturbed areas. Current methods to assess mobility and environmental impact are mainly based on field measurements, soil monitoring, and kinetic modelling. In order to understand in detail the extent to which different mineral sources can give rise to mercury release it is necessary to investigate the complexity at the microscopic level and the possible degradation/dissolution processes. In this work, we investigated the potential for mobilization of mercury structurally trapped in three relevant minerals occurring in hot spring environments and mining areas, namely, cinnabar (α-HgS), corderoite (α-Hg3S2Cl2), and mercuric chloride (HgCl2). Quantum chemical methods based on density functional theory as well as more sophisticated approaches are used to assess the possibility of a) direct photoreduction and formation of elemental Hg at the surface of the minerals, providing a path for ready release in the environment; and b) reductive dissolution of the minerals in the presence of solutions containing halogens. Furthermore, we study the use of TiO2 as a potential photocatalyst for decontamination of polluted waters (mainly Hg(2+)-containing species) and air (atmospheric Hg(0)). Our results partially explain the observed pathways of Hg mobilization from relevant minerals and the microscopic mechanisms behind photocatalytic removal of Hg-based pollutants. Possible sources of disagreement with observations are discussed and further improvements to our approach are suggested. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Modeling Source Water Threshold Exceedances with Extreme Value Theory

    Science.gov (United States)

    Rajagopalan, B.; Samson, C.; Summers, R. S.

    2016-12-01

    Variability in surface water quality, influenced by seasonal and long-term climate changes, can impact drinking water quality and treatment. In particular, temperature and precipitation can impact surface water quality directly or through their influence on streamflow and dilution capacity. Furthermore, they also impact land surface factors, such as soil moisture and vegetation, which can in turn affect surface water quality, in particular, levels of organic matter in surface waters which are of concern. All of these will be exacerbated by anthropogenic climate change. While some source water quality parameters, particularly Total Organic Carbon (TOC) and bromide concentrations, are not directly regulated for drinking water, these parameters are precursors to the formation of disinfection byproducts (DBPs), which are regulated in drinking water distribution systems. These DBPs form when a disinfectant, added to the water to protect public health against microbial pathogens, most commonly chlorine, reacts with dissolved organic matter (DOM), measured as TOC or dissolved organic carbon (DOC), and inorganic precursor materials, such as bromide. Therefore, understanding and modeling the extremes of TOC and Bromide concentrations is of critical interest for drinking water utilities. In this study we develop nonstationary extreme value analysis models for threshold exceedances of source water quality parameters, specifically TOC and bromide concentrations. In this, the threshold exceedances are modeled as Generalized Pareto Distribution (GPD) whose parameters vary as a function of climate and land surface variables - thus, enabling to capture the temporal nonstationarity. We apply these to model threshold exceedance of source water TOC and bromide concentrations at two locations with different climate and find very good performance.

  16. Real-Time Continuous Response Spectra Exceedance Calculation

    Science.gov (United States)

    Vernon, Frank; Harvey, Danny; Lindquist, Kent; Franke, Mathias

    2017-04-01

    A novel approach is presented for near real-time earthquake alarms for critical structures at distributed locations using real-time estimation of response spectra obtained from near free-field motions. Influential studies dating back to the 1980s identified spectral response acceleration as a key ground motion characteristic that correlates well with observed damage in structures. Thus, monitoring and reporting on exceedance of spectra-based thresholds are useful tools for assessing the potential for damage to facilities or multi-structure campuses based on input ground motions only. With as little as one strong-motion station per site, this scalable approach can provide rapid alarms on the damage status of remote towns, critical infrastructure (e.g., hospitals, schools) and points of interests (e.g., bridges) for a very large number of locations enabling better rapid decision making during critical and difficult immediate post-earthquake response actions. Real-time calculation of PSA exceedance and alarm dissemination are enabled with Bighorn, a module included in the Antelope software package that combines real-time spectral monitoring and alarm capabilities with a robust built-in web display server. Examples of response spectra from several M 5 events recorded by the ANZA seismic network in southern California will be presented.

  17. Staging Mobilities / Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2015-01-01

    asks: what are the physical, social, technical, and cultural conditions to the staging of contemporary urban mobilities? The theoretical framing in the Staging mobilities book is applied to four in-depth cases in the accompanying volume Designing mobilities.This book explore how places, sites......In recent years, urban research has taken a ‘mobilities turn’. There has been a developing realisation that mobilities do not ‘just happen.’ Mobilities are carefully and meticulously designed, planned and staged (from above). However, they are equally importantly acted out, performed and lived......, and systems 'hosting' these multiple and complex mobilities are designed and how they are staging these in terms of their physical layout. By analysing specific cases of ‘mobilities design’ related to the four modes of moving; Walk, Bike, Train, and Car, the book uncover important and until now neglected...

  18. Room- and low-temperature assessment of pseudomorphic AlGaAs/InGaAs/GaAS high-electron-mobility transistor structures by photoluminescence spectroscopy

    Science.gov (United States)

    Gilperez, J. M.; Sanchez-Rojas, J. L.; Munoz, E.; Calleja, E.; David, J. P. R.; Reddy, M.; Hill, G.; Sanchez-Dehesa, J.

    1994-11-01

    The use of room- and low-temperature photoluminescence (PL) spectroscopy for the assessment of n-type pseudomorphic AlGaAs/InGaAs/GaAs high-electron-mobility transistor stransitor structures is reported. We describe a method to determine the InAs mole fraction x, the channel layer thickness L, and the confined two-dimensional electron gas density (n(sub s)), based on the comparison between the PL transitions and the recombination energies derived from self-consistent calculations of the subband structure. A detailed analysis of the optical transitions and their dependence on the Fermi level position and temperature is performed. It is shown that, in real devices, the high sensitivity of the recombination energies and intensities on small changes of the parameters x, L, and n(sub s) allows us to detect deviations from their nominal structural parameters within the uncertainty of the molecular beam epitaxy growth technique. The present assessment procedure has been applied to a significant number of samples, and it has been backed by independent measurements of these parameters by more sophisticated techniques such as Shubnikov-de Haas and PL excitation in standard and gated samples, and by physical techniques like transmission electron microscopy and Auger spectroscopy.

  19. a-Axis GaN/AlN/AlGaN Core-Shell Heterojunction Microwires as Normally Off High Electron Mobility Transistors.

    Science.gov (United States)

    Song, Weidong; Wang, Rupeng; Wang, Xingfu; Guo, Dexiao; Chen, Hang; Zhu, Yuntao; Liu, Liu; Zhou, Yu; Sun, Qian; Wang, Li; Li, Shuti

    2017-11-29

    Micro/nanowire-based devices have been envisioned as a promising new route toward improved electronic and optoelectronic applications, which attracts considerable research interests. However, suffering from applicable strategies to synthesize uniform core-shell structures to meet the requirement for the investigations of electrical transport behaviors along the length direction or high electron mobility transistor (HEMT) devices, heterojunction wire-based electronics have been explored limitedly. In the present work, GaN/AlN/AlGaN core-shell heterojunction microwires on patterned Si substrates were synthesized without any catalyst via metalorganic chemical vapor deposition. The as-synthesized microwires had low dislocation, sharp, and uniform heterojunction interfaces. Electrical transport performances were evaluated by fabricating HEMTs on the heterojunction microwire channels. Results demonstrated that a normally off operation was achieved with a threshold voltage of 1.4 V, a high on/off current ratio of 108, a transconductance of 165 mS/mm, and a low subthreshold swing of 81 mV/dec. The normally off operation may attribute to the weak polarization along semipolar facets of the heterojunction, which leads to weak constrain of 2DEG.

  20. Threshold exceedance risk assessment in complex space-time systems

    Science.gov (United States)

    Angulo, José M.; Madrid, Ana E.; Romero, José L.

    2015-04-01

    Environmental and health impact risk assessment studies most often involve analysis and characterization of complex spatio-temporal dynamics. Recent developments in this context are addressed, among other objectives, to proper representation of structural heterogeneities, heavy-tailed processes, long-range dependence, intermittency, scaling behavior, etc. Extremal behaviour related to spatial threshold exceedances can be described in terms of geometrical characteristics and distribution patterns of excursion sets, which are the basis for construction of risk-related quantities, such as in the case of evolutionary study of 'hotspots' and long-term indicators of occurrence of extremal episodes. Derivation of flexible techniques, suitable for both the application under general conditions and the interpretation on singularities, is important for practice. Modern risk theory, a developing discipline motivated by the need to establish solid general mathematical-probabilistic foundations for rigorous definition and characterization of risk measures, has led to the introduction of a variety of classes and families, ranging from some conceptually inspired by specific fields of applications, to some intended to provide generality and flexibility to risk analysts under parametric specifications, etc. Quantile-based risk measures, such as Value-at-Risk (VaR), Average Value-at-Risk (AVaR), and generalization to spectral measures, are of particular interest for assessment under very general conditions. In this work, we study the application of quantile-based risk measures in the spatio-temporal context in relation to certain geometrical characteristics of spatial threshold exceedance sets. In particular, we establish a closed-form relationship between VaR, AVaR, and the expected value of threshold exceedance areas and excess volumes. Conditional simulation allows us, by means of empirical global and local spatial cumulative distributions, the derivation of various statistics of

  1. Predictions of flood warning threshold exceedance computed with logistic regression

    Science.gov (United States)

    Diomede, Tommaso; Marsigli, Chiara; Stefania Tesini, Maria

    2017-04-01

    A method based on logistic regression is proposed for the prediction of river level threshold exceedance at different lead times (from +6h up to +42h). The aim of the study is to provide a valuable tool for the issue of warnings by the authority responsible of public safety in case of flood. The role of different precipitation periods as predictors for the exceedance of a fixed river level has been investigated, in order to derive significant information for flood forecasting. Based on catchment-averaged values, a separation of "antecedent" and "peak-triggering" rainfall amounts as independent variables is attempted. In particular, the following flood-related precipitation periods have been considered: (i) the period from 1 to n days before the forecast issue time, which may be relevant for the soil saturation ("state of the catchment"), (ii) the last 24 hours, which may be relevant for the current water level in the river ("state of the river"), and (iii) the period from 0 to x hours in advance with respect to the forecast issue time, when the flood-triggering precipitation generally occurs ("state of the atmosphere"). Several combinations and values of these predictors have been tested to optimise the method implementation. In particular, the period for the precursor antecedent precipitation ranges between 5 and 45 days; the current "state of the river" can be represented by the last 24-h precipitation or, as alternative, by the current river level. The flood-triggering precipitation has been cumulated over the next 18-42 hours, or the previous 6-12h, according to the forecast lead time. The proposed approach requires a specific implementation of logistic regression for each river section and warning threshold. The method performance has been evaluated over several catchments in the Emilia-Romagna Region, northern Italy, which dimensions range from 100 to 1000 km2. A statistical analysis in terms of false alarms, misses and related scores was carried out by using

  2. An open-access, mobile compatible, electronic patient register for rheumatic heart disease ('eRegister') based on the World Heart Federation's framework for patient registers.

    Science.gov (United States)

    van Dam, Joris; Musuku, John; Zühlke, Liesl J; Engel, Mark E; Nestle, Nick; Tadmor, Brigitta; Spector, Jonathan; Mayosi, Bongani M

    2015-01-01

    Rheumatic heart disease (RHD) remains a major disease burden in low-resource settings globally. Patient registers have long been recognised to be an essential instrument in RHD control and elimination programmes, yet to date rely heavily on paper-based data collection and non-networked data-management systems, which limit their functionality. To assess the feasibility and potential benefits of producing an electronic RHD patient register. We developed an eRegister based on the World Heart Federation's framework for RHD patient registers using CommCare, an open-source, cloud-based software for health programmes that supports the development of customised data capture using mobile devices. The resulting eRegistry application allows for simultaneous data collection and entry by field workers using mobile devices, and by providers using computer terminals in clinics and hospitals. Data are extracted from CommCare and are securely uploaded into a cloud-based database that matches the criteria established by the WHF framework. The application can easily be tailored to local needs by modifying existing variables or adding new ones. Compared with traditional paper-based data-collection systems, the eRegister reduces the risk of data error, synchronises in real-time, improves clinical operations and supports management of field team operations. The user-friendly eRegister is a low-cost, mobile, compatible platform for RHD treatment and prevention programmes based on materials sanctioned by the World Heart Federation. Readily adaptable to local needs, this paperless RHD patient register program presents many practical benefits.

  3. Experiences in running a complex electronic data capture system using mobile phones in a large-scale population trial in southern Nepal.

    Science.gov (United States)

    Style, Sarah; Beard, B James; Harris-Fry, Helen; Sengupta, Aman; Jha, Sonali; Shrestha, Bhim P; Rai, Anjana; Paudel, Vikas; Thondoo, Meelan; Pulkki-Brannstrom, Anni-Maria; Skordis-Worrall, Jolene; Manandhar, Dharma S; Costello, Anthony; Saville, Naomi M

    2017-01-01

    The increasing availability and capabilities of mobile phones make them a feasible means of data collection. Electronic Data Capture (EDC) systems have been used widely for public health monitoring and surveillance activities, but documentation of their use in complicated research studies requiring multiple systems is limited. This paper shares our experiences of designing and implementing a complex multi-component EDC system for a community-based four-armed cluster-Randomised Controlled Trial in the rural plains of Nepal, to help other researchers planning to use EDC for complex studies in low-income settings. We designed and implemented three interrelated mobile phone data collection systems to enrol and follow-up pregnant women (trial participants), and to support the implementation of trial interventions (women's groups, food and cash transfers). 720 field staff used basic phones to send simple coded text messages, 539 women's group facilitators used Android smartphones with Open Data Kit Collect, and 112 Interviewers, Coordinators and Supervisors used smartphones with CommCare. Barcoded photo ID cards encoded with participant information were generated for each enrolled woman. Automated systems were developed to download, recode and merge data for nearly real-time access by researchers. The systems were successfully rolled out and used by 1371 staff. A total of 25,089 pregnant women were enrolled, and 17,839 follow-up forms completed. Women's group facilitators recorded 5717 women's groups and the distribution of 14,647 food and 13,482 cash transfers. Using EDC sped up data collection and processing, although time needed for programming and set-up delayed the study inception. EDC using three interlinked mobile data management systems (FrontlineSMS, ODK and CommCare) was a feasible and effective method of data capture in a complex large-scale trial in the plains of Nepal. Despite challenges including prolonged set-up times, the systems met multiple data

  4. Avulsion Fracture of Brachioradialis Muscle Origin: An Exceedingly Rare Entity: A Case Report

    Directory of Open Access Journals (Sweden)

    Behera G

    2016-07-01

    Full Text Available Avulsion fracture of the brachioradialis origin at its proximal attachment on the lateral supracondylar ridge of the distal humerus is exceedingly rare, and only two cases have been reported in the literature so far. In this article, we present a 38 years old patient who sustained a closed avulsion fracture of the lateral supracondylar ridge of left humerus at the proximal attachment of brachioradialis following a fall backwards on outstretched hand after being struck by a lorry from behind while riding on a two-wheeler (motorcycle. He was managed with above elbow plaster for four weeks followed by elbow and wrist mobilization. At final followup, the patient had painless full range elbow motion with good elbow flexion strength. The unique mechanism by which this avulasion fracture occurred is explained on the basis of the mode of injury, position of the limb and structure and function of the brachioradialis muscle.

  5. When Aspirations Exceed Expectations: Quixotic Hope Increases Depression among Students.

    Science.gov (United States)

    Greenaway, Katharine H; Frye, Margaret; Cruwys, Tegan

    2015-01-01

    A paradox exists in modern schooling: students are simultaneously more positive about the future and more depressed than ever. We suggest that these two phenomena may be linked. Two studies demonstrated that students are more likely to be depressed when educational aspirations exceed expectations. In Study 1 (N = 85) aspiring to a thesis grade higher than one expected predicted greater depression at the beginning and end of the academic year. In Study 2 (N = 2820) aspiring to a level of education (e.g., attending college) higher than one expected to achieve predicted greater depression cross-sectionally and five years later. In both cases the negative effects of aspiring high while expecting low persisted even after controlling for whether or not students achieved their educational aspirations. These findings highlight the danger of teaching students to aspire higher without also investing time and money to ensure that students can reasonably expect to achieve their educational goals.

  6. When Aspirations Exceed Expectations: Quixotic Hope Increases Depression among Students.

    Directory of Open Access Journals (Sweden)

    Katharine H Greenaway

    Full Text Available A paradox exists in modern schooling: students are simultaneously more positive about the future and more depressed than ever. We suggest that these two phenomena may be linked. Two studies demonstrated that students are more likely to be depressed when educational aspirations exceed expectations. In Study 1 (N = 85 aspiring to a thesis grade higher than one expected predicted greater depression at the beginning and end of the academic year. In Study 2 (N = 2820 aspiring to a level of education (e.g., attending college higher than one expected to achieve predicted greater depression cross-sectionally and five years later. In both cases the negative effects of aspiring high while expecting low persisted even after controlling for whether or not students achieved their educational aspirations. These findings highlight the danger of teaching students to aspire higher without also investing time and money to ensure that students can reasonably expect to achieve their educational goals.

  7. High mobility 2-dimensional electron gas at LaAlO3/SrTiO3 interface prepared by spin coating chemical methods

    Science.gov (United States)

    Khan, Tahira; Zhang, Hui; Zhang, Hongrui; Yan, Xi; Hong, Deshun; Han, Furong; Chen, Yuansha; Shen, Baogen; Sun, Jirong

    2017-10-01

    Highly mobile 2-dimensional electron gases (2DEGs) at the (001), (011) and (111)-oriented LaAlO3/SrTiO3 (LAO/STO) interfaces are obtained using spin coating chemical method, which is a gentle technique without plasma bombardment of the pulsed laser deposition. As revealed by x-ray diffraction spectrum and x-ray reflectivity analysis, the LAO over layer is epitaxially grown, and has a uniform thickness of ˜15 nm, ˜20 nm and ˜26 nm for (001), (011) and (111) orientations, respectively. The interfaces are well metallic down to 2 K. The carrier mobilities are ˜28 000 cm2 V-1 s-1, ˜22 000 cm2 V-1 s-1 and ˜8300 cm2 V-1 s-1 at 2 K for the (001), (011) and (111) LAO/STO interfaces, respectively, and ˜8 cm2 V-1 s-1, ˜4 cm2 V-1 s-1 and ˜4 cm2 V-1 s-1 at room temperature. The present work shows that the spin coating chemical method is a feasible approach to get high quality 2DEG at both the polar/non-polar and polar/polar interfaces.

  8. Cost-utility and cost-effectiveness studies of telemedicine, electronic, and mobile health systems in the literature: a systematic review.

    Science.gov (United States)

    de la Torre-Díez, Isabel; López-Coronado, Miguel; Vaca, Cesar; Aguado, Jesús Saez; de Castro, Carlos

    2015-02-01

    A systematic review of cost-utility and cost-effectiveness research works of telemedicine, electronic health (e-health), and mobile health (m-health) systems in the literature is presented. Academic databases and systems such as PubMed, Scopus, ISI Web of Science, and IEEE Xplore were searched, using different combinations of terms such as "cost-utility" OR "cost utility" AND "telemedicine," "cost-effectiveness" OR "cost effectiveness" AND "mobile health," etc. In the articles searched, there were no limitations in the publication date. The search identified 35 relevant works. Many of the articles were reviews of different studies. Seventy-nine percent concerned the cost-effectiveness of telemedicine systems in different specialties such as teleophthalmology, telecardiology, teledermatology, etc. More articles were found between 2000 and 2013. Cost-utility studies were done only for telemedicine systems. There are few cost-utility and cost-effectiveness studies for e-health and m-health systems in the literature. Some cost-effectiveness studies demonstrate that telemedicine can reduce the costs, but not all. Among the main limitations of the economic evaluations of telemedicine systems are the lack of randomized control trials, small sample sizes, and the absence of quality data and appropriate measures.

  9. Random nanowires of nickel doped TiO2 with high surface area and electron mobility for high efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Archana, P S; Naveen Kumar, E; Vijila, C; Ramakrishna, S; Yusoff, M M; Jose, R

    2013-01-28

    Mesoporous TiO(2) with a large specific surface area (~150 m(2) g(-1)) is the most successful material in dye-sensitized solar cells so far; however, its inferior charge mobility is a major efficiency limiter. This paper demonstrates that random nanowires of Ni-doped TiO(2) (Ni:TiO(2)) have a dramatic influence on the particulate and charge transport properties. Nanowires (dia ~60 nm) of Ni:TiO(2) with a specific surface area of ~80 m(2) g(-1) were developed by an electrospinning technique. The band gap of the Ni:TiO(2) shifted to the visible region upon doping of 5 at% Ni atoms. The Mott-Schottky analysis shows that the flat band potential of Ni:TiO(2) shifts to a more negative value than the undoped samples. The electrochemical impedance spectroscopic measurements showed that the Ni:TiO(2) offer lower charge transport resistance, higher charge recombination resistance, and enhanced electron lifetime compared to the undoped samples. The dye-sensitized solar cells fabricated using the Ni:TiO(2) nanowires showed an enhanced photoconversion efficiency and short-circuit current density compared to the undoped analogue. The transient photocurrent measurements showed that the Ni:TiO(2) has improved charge mobility compared with TiO(2) and is several orders of magnitude higher compared to the P25 particles.

  10. Threading dislocation movement in AlGaN/GaN-on-Si high electron mobility transistors under high temperature reverse bias stressing

    Directory of Open Access Journals (Sweden)

    W. A. Sasangka

    2016-09-01

    Full Text Available Dislocations are known to be associated with both physical and electrical degradation mechanisms of AlGaN/GaN-on-Si high electron mobility transistors (HEMTs. We have observed threading dislocation movement toward the gate-edges in AlGaN/GaN-on-Si HEMT under high reverse bias stressing. Stressed devices have higher threading dislocation densities (i.e. ∼5 × 109/cm2 at the gate-edges, as compared to unstressed devices (i.e. ∼2.5 × 109/cm2. Dislocation movement correlates well with high tensile stress (∼1.6 GPa at the gate-edges, as seen from inverse piezoelectric calculations and x-ray synchrotron diffraction residual stress measurements. Based on Peierls stress calculation, we believe that threading dislocations move via glide in 〈 11 2 ¯ 0 〉 / { 1 1 ¯ 00 } and 〈 11 2 ¯ 0 〉 / { 1 1 ¯ 01 } slip systems. This result illustrates the importance of threading dislocation mobility in controlling the reliability of AlGaN/GaN-on-Si HEMTs.

  11. Ultrasensitive detection of Hg{sup 2+} using oligonucleotide-functionalized AlGaN/GaN high electron mobility transistor

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Junjie [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China); Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Li, Jiadong; Miao, Bin; Wu, Dongmin, E-mail: dmwu2008@sinano.ac.cn [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215125 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wang, Jine; Pei, Renjun, E-mail: rjpei2011@sinano.ac.cn [Division of Nanobiomedicine, Key Laboratory for Nano-Bio Interface Research, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Wu, Zhengyan, E-mail: zywu@ipp.ac.cn [Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031 (China)

    2014-08-25

    An oligonucleotide-functionalized ion sensitive AlGaN/GaN high electron mobility transistor (HEMT) was fabricated to detect trace amounts of Hg{sup 2+}. The advantages of ion sensitive AlGaN/GaN HEMT and highly specific binding interaction between Hg{sup 2+} and thymines were combined. The current response of this Hg{sup 2+} ultrasensitive transistor was characterized. The current increased due to the accumulation of Hg{sup 2+} ions on the surface by the highly specific thymine-Hg{sup 2+}-thymine recognition. The dynamic linear range for Hg{sup 2+} detection has been determined in the concentrations from 10{sup −14} to 10{sup −8} M and a detection limit below 10{sup −14} M level was estimated, which is the best result of AlGaN/GaN HEMT biosensors for Hg{sup 2+} detection till now.

  12. Impact of recess etching and surface treatments on ohmic contacts regrown by molecular-beam epitaxy for AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Joglekar, S.; Azize, M.; Palacios, T. [Microsystems Technology Laboratories, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Beeler, M.; Monroy, E. [Université Grenoble-Alpes, 38000 Grenoble (France); CEA Grenoble, INAC-PHELIQS, 38000 Grenoble (France)

    2016-07-25

    Ohmic contacts fabricated by regrowth of n{sup +} GaN are favorable alternatives to metal-stack-based alloyed contacts in GaN-based high electron mobility transistors. In this paper, the influence of reactive ion dry etching prior to regrowth on the contact resistance in AlGaN/GaN devices is discussed. We demonstrate that the dry etch conditions modify the surface band bending, dangling bond density, and the sidewall depletion width, which influences the contact resistance of regrown contacts. The impact of chemical surface treatments performed prior to regrowth is also investigated. The sensitivity of the contact resistance to the surface treatments is found to depend upon the dangling bond density of the sidewall facets exposed after dry etching. A theoretical model has been developed in order to explain the observed trends.

  13. Ultrahigh sensitive sub-terahertz detection by InP-based asymmetric dual-grating-gate high-electron-mobility transistors and their broadband characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Kurita, Y.; Satou, A., E-mail: a-satou@riec.tohoku.ac.jp; Kobayashi, K.; Boubanga Tombet, S.; Suemitsu, T.; Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Ducournau, G. [Institut d' Electronique, de Microélectronique et de Nanotechnologie, 59562 Villeneuve d' Ascq Cedex (France); Coquillat, D.; Knap, W. [Laboratoire Charles Coulomb, UMR 5221, Université Montpellier 2 - CNRS, F-34095 Montpellier (France); Meziani, Y. M. [Departamento de Fisica Aplicada, Universidad de Salamanca, Salamanca 37008 (Spain); Popov, V. V. [Kotelnikov Institute of Radio Engineering and Electronics, 410019 Saratov (Russian Federation)

    2014-06-23

    We report on room-temperature plasmonic detection of sub-terahertz radiation by InAlAs/InGaAs/InP high electron mobility transistors with an asymmetric dual-grating-gate structure. Maximum responsivities of 22.7 kV/W at 200 GHz and 21.5 kV/W at 292 GHz were achieved under unbiased drain-to-source condition. The minimum noise equivalent power was estimated to be 0.48 pW/Hz{sup 0.5} at 200 GHz at room temperature, which is the record-breaking value ever reported for plasmonic THz detectors. Frequency dependence of the responsivity in the frequency range of 0.2–2 THz is in good agreement with the theory.

  14. Investigation of high sensitivity radio-frequency readout circuit based on AlGaN/GaN high electron mobility transistor

    Science.gov (United States)

    Zhang, Xiao-Yu; Tan, Ren-Bing; Sun, Jian-Dong; Li, Xin-Xing; Zhou, Yu; Lü, Li; Qin, Hua

    2015-10-01

    An AlGaN/GaN high electron mobility transistor (HEMT) device is prepared by using a semiconductor nanofabrication process. A reflective radio-frequency (RF) readout circuit is designed and the HEMT device is assembled in an RF circuit through a coplanar waveguide transmission line. A gate capacitor of the HEMT and a surface-mounted inductor on the transmission line are formed to generate LC resonance. By tuning the gate voltage Vg, the variations of gate capacitance and conductance of the HEMT are reflected sensitively from the resonance frequency and the magnitude of the RF reflection signal. The aim of the designed RF readout setup is to develop a highly sensitive HEMT-based detector. Project supported by the National Natural Science Foundation of China (Grant No. 61107093), the Suzhou Science and Technology Project, China (Grant No. ZXG2012024), and the Youth Innovation Promotion Association, Chinese Academy of Sciences (Grant No. 2012243).

  15. Electrothermal evaluation of thick GaN epitaxial layers and AlGaN/GaN high-electron-mobility transistors on large-area engineered substrates

    Science.gov (United States)

    Anderson, Travis J.; Koehler, Andrew D.; Tadjer, Marko J.; Hite, Jennifer K.; Nath, Anindya; Mahadik, Nadeemullah A.; Aktas, Ozgur; Odnoblyudov, Vladimir; Basceri, Cem; Hobart, Karl D.; Kub, Francis J.

    2017-12-01

    AlGaN/GaN high-electron-mobility transistor (HEMT) device layers were grown by metal organic chemical vapor deposition (MOCVD) on commercial engineered QST™ substrates to demonstrate a path to scalable, cost-effective foundry processing while supporting the thick epitaxial layers required for power HEMT structures. HEMT structures on 150 mm Si substrates were also evaluated. The HEMTs on engineered substrates exhibited material quality, DC performance, and forward blocking performance superior to those of the HEMT on Si. GaN device layers up to 15 µm were demonstrated with a wafer bow of 1 µm, representing the thickest films grown on 150-mm-diameter substrates with low bow to date.

  16. Delivery of Dietary and Lifestyle Interventions in Pregnancy: is it Time to Promote the Use of Electronic and Mobile Health Technologies?

    Science.gov (United States)

    O'Brien, Cecelia M; Cramp, Courtney; Dodd, Jodie M

    2016-03-01

    Fifty percent of women who enter pregnancy are overweight or obese, increasing complications for both the mother and the infant, along with significant burden on individuals and the health care system. Pregnancy represents a "teachable moment" in a woman's life, however, antenatal interventions focusing on improving dietary and physical activity patterns have been associated with modest behavior change. There are many barriers that need to be overcome, including lack of knowledge, access and time pressures. Advancing mobile and electronic health technologies may represent an adjunct tool to support traditional face-to-face consultations and facilitate behavior change, but further rigorous evaluation of the technologies and their impact on health outcomes is required. Well-designed antenatal intervention trials with particular attention to the structure and method of information provision are required to further assess the feasibility of such technology. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  17. Design and characterisation of high electron mobility transistors for use in a monolithic GaAs X-ray imaging sensor

    Energy Technology Data Exchange (ETDEWEB)

    Boardman, D.A. E-mail: d.boardman@surrey.ac.uk; Sellin, P.J

    2001-06-21

    A new design of monolithic GaAs pixel detector is proposed for medical and synchrotron applications. In this device a semi-insulating GaAs wafer will be used as both the detector element and the substrate for the integrated charge readout matrix. The charge readout matrix consists of High Electron Mobility Transistors (HEMTs), which are grown epitaxially onto the GaAs substrate. Experimental characterisation of HEMTs has been carried out and their suitability for the proposed imaging device is assessed. Temperature measurements on initial devices showed the threshold voltage to be stable from room temperature down to -15 degree sign C. HEMT designs with lower leakage current that operate in enhancement mode have been fabricated and modelled using the Silvaco simulation package. These optimised devices have been fabricated using a gate recess, and exhibit enhancement mode operation and significantly reduced gate leakage currents.

  18. Strain control of AlGaN/GaN high electron mobility transistor structures on silicon (111) by plasma assisted molecular beam epitaxy

    Science.gov (United States)

    Aidam, Rolf; Diwo, Elke; Rollbühler, Nicola; Kirste, Lutz; Benkhelifa, Fouad

    2012-06-01

    This paper reports on the use of plasma assisted molecular beam epitaxy of AlGaN/GaN-based high electron mobility transistor structures grown on 4 in. Si (111) substrates. In situ measurements of wafer curvature during growth proved to be a very powerful method to analyze the buffer layer's thickness dependent strain. The Ga/N ratio at the beginning of growth of the GaN buffer layer is the critical parameter to control the compressive strain of the entire grown structure. An engineered amount of compressive strain must be designed into the structure to perfectly compensate for the tensile strain caused by differences in the thermal expansion coefficient between the epi-layer and substrate during sample cool down from growth temperatures. A maximum film thickness of 4.2 μm was achieved without the formation of any cracks and a negligible bow of the wafers below 10 μm. Measurement of the as-grown wafers revealed depth profiles of the charge carrier concentration comparable to values achieved on SiC substrates and mobility values of the two dimensional electron gas in the range 1230 to 1350 cm2/Vs at a charge carrier concentration of 6.5-7 1012/cm2. First results on processed wafers with 2 μm thick buffer layer indicate very promising results with a resistance of the buffer, measured on 200 μm long contacts with 15 μm pitch, in the range of R > 109 Ω at 100 V and breakdown voltages up to 550 V.

  19. Facial Plastic Surgery Patient Resources Exceed National Institute Recommendations.

    Science.gov (United States)

    Chu, Michael W; Cook, Julia A; Tholpady, Sunil S; Schmalbach, Cecelia E; Momeni, Arash

    2017-05-01

    Patient education is essential in enhancing the physician-patient therapeutic alliance, patient satisfaction, and clinical outcomes. The American Medical Association and National Institute of Health recommend that information be written at a 6th-grade reading level, but online resources often exceed patient literacy. The purpose of this study is to assess readability of online material for facial plastics procedures presented on academic plastic surgery and otolaryngology websites.An Internet search was performed of all academic institutions that had both plastic surgery and otolaryngology training programs who offered patient information on facial plastic surgery procedures. National society websites for both plastic surgery and otolaryngology were also analyzed. All procedural information was compiled and readability analyses were performed. A 2-tailed Z-test was used to compare scores, and statistical significance was set at P material. The overall average readability for all information was at a 10th-grade reading level. The national plastic surgery website had a significantly higher word count and number of syllables per word compared to the national otolaryngology website (P materials are a potential hindrance to patient education, satisfaction, and decision making. Healthcare institutions should consider writing new materials with simpler language that would be accessible to patients.

  20. 3-Dimensional ZnO/CdS nanocomposite with high mobility as an efficient electron transport layer for inverted polymer solar cells.

    Science.gov (United States)

    Wang, Yilin; Fu, Haiyan; Wang, Ying; Tan, Licheng; Chen, Lie; Chen, Yiwang

    2016-04-28

    The inclusions of solution-processed ZnO electron transport layers (ETLs) of inverted polymer solar cells can lead to various surface defects, which can act as interfacial recombination centers for photogenerated charges and thereby can lead to degradation of the device performance. Three-dimensional (3D) CdS with different morphologies, such as flower-like CdS (F-CdS), branched CdS (B-CdS), and spherical CdS (S-CdS), are synthesized to modify ZnO ETLs, by effectively removing the intragap states of the ZnO nanocrystal films by forming ZnO/F-CdS, ZnO/B-CdS, and ZnO/S-CdS composite ETLs, respectively. Moreover, ZnO/CdS possesses higher electron mobility and provides a larger interface between the ETL and active layer, which is beneficial for enhancing the power conversion efficiency (PCE) of the inverted organic solar cells. In particular, a device based on a ZnO/S-CdS ETL and thieno[3,4-b]-thiophene/benzodithiophene (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) active layer achieved a PCE of 8.0%, together with better long-term stability.

  1. Epitaxial ZnO gate dielectrics deposited by RF sputter for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors

    Science.gov (United States)

    Yoon, Seonno; Lee, Seungmin; Kim, Hyun-Seop; Cha, Ho-Young; Lee, Hi-Deok; Oh, Jungwoo

    2018-01-01

    Radio frequency (RF)-sputtered ZnO gate dielectrics for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) were investigated with varying O2/Ar ratios. The ZnO deposited with a low oxygen content of 4.5% showed a high dielectric constant and low interface trap density due to the compensation of oxygen vacancies during the sputtering process. The good capacitance–voltage characteristics of ZnO-on-AlGaN/GaN capacitors resulted from the high crystallinity of oxide at the interface, as investigated by x-ray diffraction and high-resolution transmission electron microscopy. The MOS-HEMTs demonstrated comparable output electrical characteristics with conventional Ni/Au HEMTs but a lower gate leakage current. At a gate voltage of ‑20 V, the typical gate leakage current for a MOS-HEMT with a gate length of 6 μm and width of 100 μm was found to be as low as 8.2 × 10‑7 mA mm‑1, which was three orders lower than that of the Ni/Au Schottky gate HEMT. The reduction of the gate leakage current improved the on/off current ratio by three orders of magnitude. These results indicate that RF-sputtered ZnO with a low O2/Ar ratio is a good gate dielectric for high-performance AlGaN/GaN MOS-HEMTs.

  2. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    Science.gov (United States)

    Anand, M. J.; Ng, G. I.; Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C.; Syamal, B.; Zhou, X.

    2015-02-01

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-RDS[ON]) and threshold-voltage shift (ΔVth) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (IDS-VDS) and drain current (ID) transients. Different EF was realized with devices of different gate-drain spacing (Lgd) under the same OFF-state stress. Under high-EF (Lgd = 2 μm), the devices exhibited higher dyn-RDS[ON] degradation but a small ΔVth (˜120 mV). However, at low-EF (Lgd = 5 μm), smaller dyn-RDS[ON] degradation but a larger ΔVth (˜380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-RDS[ON] degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔVth. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by ID-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

  3. AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors with reduced leakage current and enhanced breakdown voltage using aluminum ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shichuang [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Fu, Kai, E-mail: kfu2009@sinano.ac.cn, E-mail: cqchen@mail.hust.edu.cn; Yu, Guohao; Zhang, Zhili; Song, Liang; Deng, Xuguang; Li, Shuiming; Sun, Qian; Cai, Yong; Zhang, Baoshun [Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, Suzhou 215123 (China); Qi, Zhiqiang; Dai, Jiangnan; Chen, Changqing, E-mail: kfu2009@sinano.ac.cn, E-mail: cqchen@mail.hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2016-01-04

    This letter has studied the performance of AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors on silicon substrate with GaN buffer treated by aluminum ion implantation for insulating followed by a channel regrown by metal–organic chemical vapor deposition. For samples with Al ion implantation of multiple energies of 140 keV (dose: 1.4 × 10{sup 14} cm{sup −2}) and 90 keV (dose: 1 × 10{sup 14} cm{sup −2}), the OFF-state leakage current is decreased by more than 3 orders and the breakdown voltage is enhanced by nearly 6 times compared to the samples without Al ion implantation. Besides, little degradation of electrical properties of the 2D electron gas channel is observed where the maximum drain current I{sub DSmax} at a gate voltage of 3 V was 701 mA/mm and the maximum transconductance g{sub mmax} was 83 mS/mm.

  4. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture

    Energy Technology Data Exchange (ETDEWEB)

    Deen, David A., E-mail: david.deen@alumni.nd.edu; Storm, David F.; Scott Katzer, D.; Bass, R.; Meyer, David J. [Naval Research Laboratory, Electronics Science and Technology Division, Washington, DC 20375 (United States)

    2016-08-08

    A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics f{sub t}/f{sub max} of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with f{sub t}/f{sub max} of 48/60 GHz.

  5. Investigation of trap states in high Al content AlGaN/GaN high electron mobility transistors by frequency dependent capacitance and conductance analysis

    Directory of Open Access Journals (Sweden)

    Jie-Jie Zhu

    2014-03-01

    Full Text Available Trap states in Al0.55Ga0.45N/GaN Schottky-gate high-electron-mobility transistors (S-HEMTs and Al2O3/Al0.55Ga0.45N/GaN metal-oxide-semiconductor HEMTs (MOS-HEMTs were investigated with conductance method in this paper. Surface states with time constant of (0.09–0.12 μs were found in S-HEMTs, and electron tunneling rather than emission was deemed to be the dominant de-trapping mechanism due to the high electric field in high Al content barrier. The density of surface states evaluated in S-HEMTs was (1.02–4.67×1013 eV−1·cm−2. Al2O3 gate insulator slightly reduced the surface states, but introduced low density of new traps with time constant of (0.65–1.29 μs into MOS-HEMTs.

  6. Polarization-mediated Debye-screening of surface potential fluctuations in dual-channel AlN/GaN high electron mobility transistors

    Science.gov (United States)

    Deen, David A.; Miller, Ross A.; Osinsky, Andrei V.; Downey, Brian P.; Storm, David F.; Meyer, David J.; Scott Katzer, D.; Nepal, Neeraj

    2016-12-01

    A dual-channel AlN/GaN/AlN/GaN high electron mobility transistor (HEMT) architecture is proposed, simulated, and demonstrated that suppresses gate lag due to surface-originated trapped charge. Dual two-dimensional electron gas (2DEG) channels are utilized such that the top 2DEG serves as an equipotential that screens potential fluctuations resulting from surface trapped charge. The bottom channel serves as the transistor's modulated channel. Two device modeling approaches have been performed as a means to guide the device design and to elucidate the relationship between the design and performance metrics. The modeling efforts include a self-consistent Poisson-Schrodinger solution for electrostatic simulation as well as hydrodynamic three-dimensional device modeling for three-dimensional electrostatics, steady-state, and transient simulations. Experimental results validated the HEMT design whereby homo-epitaxial growth on free-standing GaN substrates and fabrication of the same-wafer dual-channel and recessed-gate AlN/GaN HEMTs have been demonstrated. Notable pulsed-gate performance has been achieved by the fabricated HEMTs through a gate lag ratio of 0.86 with minimal drain current collapse while maintaining high levels of dc and rf performance.

  7. Current linearity and operation stability in Al2O3-gate AlGaN/GaN MOS high electron mobility transistors

    Science.gov (United States)

    Nishiguchi, Kenya; Kaneki, Syota; Ozaki, Shiro; Hashizume, Tamotsu

    2017-10-01

    To investigate current linearity and operation stability of metal-oxide-semiconductor (MOS) AlGaN/GaN high electron mobility transistors (HEMTs), we have fabricated and characterized the Al2O3-gate MOS-HEMTs without and with a bias annealing in air at 300 °C. Compared with the as-fabricated (unannealed) MOS HEMTs, the bias-annealed devices showed improved linearity of I D-V G curves even in the forward bias regime, resulting in increased maximum drain current. Lower subthreshold slope was also observed after bias annealing. From the precise capacitance-voltage analysis on a MOS diode fabricated on the AlGaN/GaN heterostructure, it was found that the bias annealing effectively reduced the state density at the Al2O3/AlGaN interface. This led to efficient modulation of the AlGaN surface potential close to the conduction band edge, resulting in good gate control of two-dimensional electron gas density even at forward bias. In addition, the bias-annealed MOS HEMT showed small threshold voltage shift after applying forward bias stress and stable operation even at high temperatures.

  8. Use of parallel-plate ionization chambers in reference dosimetry of NOVAC and LIAC(®) mobile electron linear accelerators for intraoperative radiotherapy: a multi-center survey.

    Science.gov (United States)

    Scalchi, Paolo; Ciccotelli, Alessia; Felici, Giuseppe; Petrucci, Assunta; Massafra, Raffaella; Piazzi, Valeria; D'Avenia, Paola; Cavagnetto, Francesca; Cattani, Federica; Romagnoli, Raffaella; Soriani, Antonella

    2017-01-01

    LIAC(®) and NOVAC are two mobile linear accelerators dedicated to intraoperative radiation therapy (IORT), generating electron beams in the energy range of 3-12 MeV. Due to high dose-per-pulse (up to 70 mGy per pulse), in 2003 the Italian National Institute of Health (ISS) stated that "for the measure of dose to water in reference conditions, ionization chambers cannot be employed and no published dosimetry protocol can be used". As a consequence, ferrous sulphate (or, alternatively alanine) dosimetry was recommended. Based on a retrospective multi-center survey, a comparison with ferrous sulphate dosimetry is now used to validate the parallel-plate ionization chambers for reference dosimetry of NOVAC and LIAC. The IAEA TRS-398 dosimetry protocol was applied except for the reference irradiation setup and the determination of the ion-recombination correction factor ks . Moreover the depth of maximum dose (R100 ) instead of zref as measurement depth was chosen by the majority of centers, thus implying a renormalization of the beam-quality correction factor kQ,Qo , based on water-air stopping power ratios. Regarding the ks determination, a previously published method, independent of ferrous sulphate dosimetry, was adopted. All the centers participating in this study had used both ferrous sulphate dosimeters and ionization chambers in water phantoms for dosimetry under reference conditions. The mean percentage difference between ionization chambers and ferrous sulphate dosimetry was -0.5% with a dispersion of 3.9% (2σ). Moreover, the uncertainty analysis allowed the agreement between ionization chambers and ferrous sulphate dosimetry to be verified. These results did not show any significant dependence on electron energy, thus indirectly confirming kQ,Qo renormalization. The results from the centers using zref as the measurement depth were similar to the other data, but further focused studies could aim at investigating possible dependences of the dose differences

  9. Monte Carlo simulation of electron beams generated by a 12 MeV dedicated mobile IORT accelerator

    Science.gov (United States)

    Iaccarino, G.; Strigari, L.; D'Andrea, M.; Bellesi, L.; Felici, G.; Ciccotelli, A.; Benassi, M.; Soriani, A.

    2011-07-01

    The aim of this study was to investigate the dosimetric characteristics of the electron beams generated by the light intraoperative accelerator, Liac® (SORDINA, Italy), using Monte Carlo (MC) calculations. Moreover we investigated the possibility of characterizing the Liac® dosimetry with a minimal set of dosimetric data. In fact accelerator commissioning requires measurements of both percentage depth doses (PDDs) and off-axis profiles for all the possible combinations of energy, applicator diameter and bevelled angle. The Liac® geometry and water phantom were simulated in a typical measurement setup, using the MC code EGSnrc/BEAMnrc. A simulated annealing optimization algorithm was used in order to find the optimal non-monoenergetic spectrum of the initial electron beam that minimizes the differences between calculated and measured PDDs. We have concluded that, for each investigated nominal energy beam, only the PDDs of applicators with diameters of 30, 70 and 100 mm and the PDD without an applicator were needed to find the optimal spectra. Finally, the output factors of the entire set of applicator diameters/bevelled angles were calculated. The differences between calculated and experimental output factors were better than 2%, with the exception of the smallest applicator which gave differences between 3% and 4% for all energies. The code turned out to be useful for checking the experimental data from various Liac® beams and will be the basis for developing a tool based on MC simulation to support the medical physicist in the commissioning phase.

  10. Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Liu, Z.S.; Chen, P.; Le, L.C.; Yang, J.; Li, X.J. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, S.M.; Zhu, J.J.; Wang, H.; Yang, H. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2014-08-01

    GaN films were grown by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The influences of MOCVD growth parameters, i.e., growth pressure, ammonia (NH{sub 3}) flux, growth temperature, trimethyl-gallium flux and H{sub 2} flux, on residual carbon concentration ([C]) were systematically investigated. Secondary ion mass spectroscopy measurements show that [C] can be effectively modulated by growth conditions. Especially, it can increase by reducing growth pressure up to two orders of magnitude. High-resistance (HR) GaN epilayer with a resistivity over 1.0 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. The mechanism of the formation of HR GaN epilayer is discussed. An Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor structure with a HR GaN buffer layer and an additional low-carbon GaN channel layer is presented, exhibiting a high two dimensional electron gas mobility of 1815 cm{sup 2}/Vs. - Highlights: • Influence of MOCVD parameters on residual carbon concentration in GaN is studied. • GaN layer with a resistivity over 1 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. • High electron mobility transistor (HEMT) structures were prepared. • Control of residual carbon content results in HEMT with high 2-D electron gas mobility.

  11. High Energy High Power Battery Exceeding PHEV40 Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Rempel, Jane [TIAX LLC, Lexington, MA (United States)

    2016-03-31

    TIAX has developed long-life lithium-ion cells that can meet and exceed the energy and power targets (200Wh/kg and 800W/kg pulse power) set out by DOE for PHEV40 batteries. To achieve these targets, we selected and scaled-up a high capacity version of our proprietary high energy and high power CAM-7® cathode material. We paired the cathode with a blended anode containing Si-based anode material capable of delivering high capacity and long life. Furthermore, we optimized the anode blend composition, cathode and anode electrode design, and selected binder and electrolyte compositions to achieve not only the best performance, but also long life. By implementing CAM-7 with a Si-based blended anode, we built and tested prototype 18650 cells that delivered measured specific energy of 198Wh/kg total energy and 845W/kg at 10% SOC (projected to 220Wh/kg in state-of-the-art 18650 cell hardware and 250Wh/kg in 15Ah pouch cells). These program demonstration cells achieved 90% capacity retention after 500 cycles in on-going cycle life testing. Moreover, we also tested the baseline CAM-7/graphite system in 18650 cells showing that 70% capacity retention can be achieved after ~4000 cycles (20 months of on-going testing). Ultimately, by simultaneously meeting the PHEV40 power and energy targets and providing long life, we have developed a Li-ion battery system that is smaller, lighter, and less expensive than current state-of-the-art Li-ion batteries.

  12. Did European temperatures in 1540 exceed present-day records?

    Science.gov (United States)

    Orth, Rene; Vogel, Martha M.; Luterbacher, Jürg; Pfister, Christian; Seneviratne, Sonia I.

    2017-04-01

    There is strong evidence that the year 1540 was exceptionally dry and warm in Central Europe. Here we infer 1540 summer temperatures from the number of dry days (NDDs) in spring (March-May) and summer (June-August) in 1540 derived from historical documentary evidence published elsewhere, and compare our estimates with present-day temperatures. We translate the NDD values into temperature distributions using a linear relationship between modeled temperature and NDD from a 3000 year pre-industrial control simulation with the Community Earth System Model (CESM). Our results show medium confidence that summer mean temperatures (T JJA) and maximum temperatures (TXx) in Central Europe in 1540 were warmer than the respective present-day mean summer temperatures (assessed between 1966-2015). The model-based reconstruction suggests further that with a probability of 40%-70%, the highest daily temperatures in 1540 were even warmer than in 2003, while there is at most a 20% probability that the 1540 mean summer temperature was warmer than that of 2003 in Central Europe. As with other state-of-the-art analyses, the uncertainty of the reconstructed 1540 summer weather in this study is considerable, for instance as extrapolation is required because 1540-like events are not captured by the employed Earth system model (ESM), and neither by other ESMs. However, in addition to paleoclimatological approaches we introduce here an independent methodology to estimate 1540 temperatures, and contribute consequently to a reduced overall uncertainty in the analysis of this event. The characterization of such events and the related climate system functioning is particularly relevant in the context of global warming and the corresponding increase of extreme heat wave magnitude and occurrence frequency. Orth, R., M.M. Vogel, J. Luterbacher, C. Pfister, and S.I. Seneviratne, (2016): Did European temperatures in 1540 exceed present-day records? Env. Res. Lett., 11, 114021, doi: 10.1088/1748-9326/11/11/114021

  13. Electron capture dissociation and drift tube ion mobility-mass spectrometry coupled with site directed mutations provide insights into the conformational diversity of a metamorphic protein.

    Science.gov (United States)

    Harvey, Sophie R; Porrini, Massimiliano; Tyler, Robert C; MacPhee, Cait E; Volkman, Brian F; Barran, Perdita E

    2015-04-28

    Ion mobility mass spectrometry can be combined with data from top-down sequencing to discern adopted conformations of proteins in the absence of solvent. This multi-technique approach has particular applicability for conformationally dynamic systems. Previously, we demonstrated the use of drift tube ion mobility-mass spectrometry (DT IM-MS) and electron capture dissociation (ECD) to study the metamorphic protein lymphotactin (Ltn). Ltn exists in equilibrium between distinct monomeric (Ltn10) and dimeric (Ltn40) folds, both of which can be preserved and probed in the gas-phase. Here, we further test this mass spectrometric framework, by examining two site directed mutants of Ltn, designed to stabilise either distinct fold in solution, in addition to a truncated form consisting of a minimum model of structure for Ltn10. The truncated mutant has similar collision cross sections to the wild type (WT), for low charge states, and is resistant to ECD fragmentation. The monomer mutant (CC3) presents in similar conformational families as observed previously for the WT Ltn monomer. As with the WT, the CC3 mutant is resistant to ECD fragmentation at low charge states. The dimer mutant W55D is found here to exist as both a monomer and dimer. As a monomer W55D exhibits similar behaviour to the WT, but as a dimer presents a much larger charge state and collision cross section range than the WT dimer, suggesting a smaller interaction interface. In addition, ECD on the W55D mutant yields greater fragmentation than for the WT, suggesting a less stable β-sheet core. The results highlight the power of MS to provide insight into dynamic proteins, providing further information on each distinct fold of Ltn. In addition we observe differences in the fold stability following single or double point mutations. This approach, therefore, has potential to be a useful tool to screen for the structural effects of mutagenesis, even when sample is limited.

  14. Carbon nanotube wires with continuous current rating exceeding 20 Amperes

    Science.gov (United States)

    Cress, Cory D.; Ganter, Matthew J.; Schauerman, Christopher M.; Soule, Karen; Rossi, Jamie E.; Lawlor, Colleen C.; Puchades, Ivan; Ubnoske, Stephen M.; Bucossi, Andrew R.; Landi, Brian J.

    2017-07-01

    A process to fabricate carbon nanotube (CNT) wires with diameters greater than 1 cm and continuous current carrying capability exceeding 20 A is demonstrated. Wires larger than 5 mm are formed using a multi-step radial densification process that begins with a densified CNT wire core followed by successive wrapping of additional CNT material to increase the wire size. This process allows for a wide range of wire diameters to be fabricated, with and without potassium tetrabromoaurate (KAuBr4) chemical doping, and the resulting electrical and thermal properties to be characterized. Electrical measurements are performed with on/off current steps to obtain the maximum current before reaching a peak CNT wire temperature of 100 °C and before failure, yielding values of instantaneous currents in excess of 45 A for KAuBr4 doped CNT wires with a diameter of 6 mm achieved prior to failure. The peak temperature of the wires at failure (˜530 °C) is correlated with the primary decomposition peak observed in thermal gravimetric analysis of a wire sample confirming that oxidation is the primary failure mode of CNT wires operated in air. The in operando stability of doped CNT wires is confirmed by monitoring the resistance and temperature, which remain largely unaltered over 40 days and 1 day for wires with 1.5 mm and 11.2 mm diameters, respectively. The 100 °C continuous current rating, or ampacity, is measured for a range of doped CNT wire diameters and corresponding linear mass densities ρL. To describe the results, a new form of the fuse-law, where the critical current is defined as I ∝ρL3 /4, is developed and shows good agreement with the experimental data. Ultimately, CNT wires are shown to be stable electrical conductors, with failure current densities in excess of 50 A in the case of a convectively cooled 11.2 mm doped CNT wire, and amenable for use in applications that have long-term, high-current demands.

  15. Efficacy and External Validity of Electronic and Mobile Phone-Based Interventions Promoting Vegetable Intake in Young Adults: A Systematic Review Protocol.

    Science.gov (United States)

    Nour, Monica Marina; Chen, Juliana; Allman-Farinelli, Margaret

    2015-07-28

    Despite social marketing campaigns and behavior change interventions, young adults remain among the lowest consumers of vegetables. The digital era offers potential new avenues for both social marketing and individually tailored programs, through texting, web, and mobile applications. The effectiveness and generalizability of such programs have not been well documented. The aim of this systematic review is to evaluate the efficacy and external validity of social marketing, electronic, and mobile phone-based (mHealth) interventions aimed at increasing vegetable intake in young adults. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol will be used to conduct this systematic review. The search strategy will be executed across eleven electronic databases using combinations of the following search terms: "online intervention", "computer-assisted therapy", "internet", "website", "cell phones", "cyber", "telemedicine", "email", "social marketing", "social media", "mass media", "young adult", and "fruit and vegetables". The reference lists of included studies will also be searched for additional citations. Titles and abstracts will be screened against inclusion criteria and full texts of potentially eligible papers will be assessed by two independent reviewers. Data from eligible papers will be extracted. Quality and risk of bias will be assessed using the Effective Public Health Practice Project (EPHPP) Quality Assessment Tool for Quantitative Studies and The Cochrane Collaboration Risk of Bias assessment tool respectively. The external validity of the studies will be determined based on components such as reach, adoption, and representativeness of participants; intervention implementation and adaption; and program maintenance and institutionalization. Results will be reported quantitatively and qualitatively. Our research is in progress. A draft of the systematic review is currently being produced for publication by the end of 2015

  16. Investigation of structural, optical, and electrical characteristics of an AlGaN/GaN high electron mobility transistor structure across a 200 mm Si(1 1 1) substrate

    Science.gov (United States)

    Perozek, J.; Lee, H.-P.; Krishnan, B.; Paranjpe, A.; Reuter, K. B.; Sadana, D. K.; Bayram, C.

    2017-02-01

    An AlGaN/GaN high electron mobility transistor (HEMT) structure is grown on a 200 mm Si(1 1 1) substrate. The AlGaN/AlN/GaN heterostructure atop, which forms the 2D electron gas, is studied via transmission electron microscopy (TEM), scanning tunneling microscopy, and TEM chemical analysis. To quantify the uniformity of structural, optical, and electrical properties of these AlGaN/GaN HEMT structures, scanning electron microscopy, optical microscopy, atomic-force microscopy, x-ray diffraction (ω/2θ scan and reciprocal space mapping) and Hall effect measurements are employed across the center, middle, and edge of the 200 mm wafer. Small thickness (GaN layers across the wafer are recorded whereas a considerable change (28%) in the electron mobility is observed across the wafer that correlates with variations in surface roughness, defectivity, and layer stress. We attribute the higher mobility in the middle of the wafer to lower interface scattering, thanks to lower surface roughness and less edge-type dislocation density. Additionally, argon (Ar) ion implantation is used as a means for planar electrical isolation, and a seven orders of magnitude decrease in leakage current is achieved when an optimum Ar dose of 1013 cm-2 is used. The feasibility of scaling AlGaN/GaN HEMTs on a 200 mm Si(1 1 1) platform is discussed.

  17. Delivering Transgenic DNA Exceeding the Carrying Capacity of AAV Vectors.

    Science.gov (United States)

    Hirsch, Matthew L; Wolf, Sonya J; Samulski, R J

    2016-01-01

    strategy for AAV-mediated large gene delivery is the use of fragment AAV (fAAV) (Dong et al., Mol Ther 18(1):87-92, 2010; Hirsch et al., Mol Ther 21(12):2205-2216, 2013; Lai et al., Mol Ther 18(1):75-79, 2010; Wu et al., Mol Ther 18(1):80-86, 2010). This strategy developed following the observation that the attempted encapsidation of transgenic cassettes exceeding the packaging capacity of the AAV capsid results in the packaging of heterogeneous single-strand genome fragments (<5 kb) of both polarities (Dong et al., Mol Ther 18(1):87-92, 2010; Hirsch et al., Mol Ther 21(12):2205-2216, 2013; Lai et al., Mol Ther 18(1):75-79, 2010; Wu et al., Mol Ther 18(1):80-86, 2010). After transduction by multiple fAAV particles, the genome fragments can undergo opposite strand annealing, followed by host-mediated DNA synthesis to reconstruct the intended oversized genome within the cell. Although, there appears to be growing debate as to the most efficient method of rAAV-mediated large gene delivery, it remains possible that additional factors including the target tissue and the transgenomic sequence factor into the selection of a particular approach for a specific application (Duan et al., Mol Ther 4(4):383-391, 2001; Ghosh et al., Mol Ther 16(1):124-130, 2008; Hirsch et al., Mol Ther 21(12):2205-2216, 2013; Trapani et al., EMBO Mol Med 6(2):194-211, 2014; Ghosh et al., Hum Gene Ther 22(1):77-83, 2011). Herein we discuss the design, production, and verification of the leading rAAV large gene delivery strategies.

  18. Electron microscopical analysis of Drosophila polytene chromosomes. V. Characteristics of structures formed by transposed DNA segments of mobile elements.

    Science.gov (United States)

    Semeshin, V F; Demakov, S A; Perez Alonso, M; Belyaeva, E S; Bonner, J J; Zhimulev, I F

    1989-03-01

    An electron microscopical (EM) analysis was performed on regions of polytene chromosomes which contained DNA segments of different genetic composition, inserted by P element-mediated transformation into the Drosophila melanogaster genome. In seven of ten regions examined, containing insertions of the hsp28-ry, hsp70-Adh, ryhsp 70-beta-gal genes and of the ry gene tetramer, new bands appeared. Lack of new bands in three other strains is apparently connected with the fusion of the inserted material to preexisting bands. The new bands do not differ morphologically from the usual bands of polytene chromosomes, and their formation is likely due to predominant insertion of DNA segments into interbands. Among the constructs examined, the minimal length of a DNA segment which appears as a new band is about 5 kb; the DNA packing ratio in the new bands varies from 30 to 50. Activation of the inserted genes by heat shock has enabled us to observe the puffing characteristics of new bands. A sequence of some one kb forms a large interband, or micropuff; the puff size is correlated with the length of the genes being activated. If a DNA segment contains a single gene, then its activation causes the decompaction of the whole band; however, when a DNA segment consists of two genes and the promoter element of the activated gene is positioned in the middle of the sequence, the band splits and only part is decompacted and puffed. The DNA packing ratio in the puffs is 1.4-3.5. The subsequent deletion of the hsp70 promoter but retention of 23, 59, and 73 by from the transcription start points leads to failure of puff formation. In all the transformed sites an increase in the total length of the interbands adjacent to the insert as compared with the initial interband was observed. This increase appears to be due to decompaction of the P element DAN flanking the inserted segments. It is shown that a DNA segment, consisting of four tandemly repeated ry gene copies and interspersed by

  19. Effect of OFF-state stress induced electric field on trapping in AlGaN/GaN high electron mobility transistors on Si (111)

    Energy Technology Data Exchange (ETDEWEB)

    Anand, M. J., E-mail: anand2@e.ntu.edu.sg, E-mail: eging@ntu.edu.sg; Ng, G. I., E-mail: anand2@e.ntu.edu.sg, E-mail: eging@ntu.edu.sg; Syamal, B.; Zhou, X. [School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Arulkumaran, S.; Manoj Kumar, C. M.; Ranjan, K.; Vicknesh, S.; Foo, S. C. [Temasek Laboratories@NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Singapore 637553 (Singapore)

    2015-02-23

    The influence of electric field (EF) on the dynamic ON-resistance (dyn-R{sub DS[ON]}) and threshold-voltage shift (ΔV{sub th}) of AlGaN/GaN high electron mobility transistors on Si has been investigated using pulsed current-voltage (I{sub DS}-V{sub DS}) and drain current (I{sub D}) transients. Different EF was realized with devices of different gate-drain spacing (L{sub gd}) under the same OFF-state stress. Under high-EF (L{sub gd} = 2 μm), the devices exhibited higher dyn-R{sub DS[ON]} degradation but a small ΔV{sub th} (∼120 mV). However, at low-EF (L{sub gd} = 5 μm), smaller dyn-R{sub DS[ON]} degradation but a larger ΔV{sub th} (∼380 mV) was observed. Our analysis shows that under OFF-state stress, the gate electrons are injected and trapped in the AlGaN barrier by tunnelling-assisted Poole-Frenkel conduction mechanism. Under high-EF, trapping spreads towards the gate-drain access region of the AlGaN barrier causing dyn-R{sub DS[ON]} degradation, whereas under low-EF, trapping is mostly confined under the gate causing ΔV{sub th}. A trap with activation energy 0.33 eV was identified in the AlGaN barrier by I{sub D}-transient measurements. The influence of EF on trapping was also verified by Silvaco TCAD simulations.

  20. Investigation of gate leakage current mechanism in AlGaN/GaN high-electron-mobility transistors with sputtered TiN

    Science.gov (United States)

    Li, Y.; Ng, G. I.; Arulkumaran, S.; Ye, G.; Liu, Z. H.; Ranjan, K.; Ang, K. S.

    2017-01-01

    The gate leakage current mechanism of AlGaN/GaN Schottky barrier diodes (SBDs) and high-electron-mobility transistors (HEMTs) with sputtered TiN is systematically investigated. The reverse leakage current (JR) of TiN SBDs increases exponentially with the increase of reverse voltage (VR) from 0 to -3.2 V (Reg. I). This conduction behavior is dominated by Poole-Frenkel emission from TiN through an interface state of 0.53 eV to the conductive dislocation-related continuum states. The obtained interface state of 0.53 eV may be due to the plasma damage to the surface of the AlGaN/GaN HEMT structure during the TiN sputtering. When the TiN SBDs are biased with -20 < VR < -3.2 V, JR saturated due to the depletion of the 2-dimensional electron gas (2DEG) channel (Reg. II). This conduction behavior is dominated by the trap-assisted tunneling through the interface state at ˜0.115 eV above the Fermi level. The three terminal OFF-state gate leakage current of AlGaN/GaN HEMTs exhibited an activation energy of 0.159 eV, which is in close agreement with the obtained interface state of ˜0.115 eV from saturated JR (Reg. II) of the SBDs. The observation of the negative temperature coefficient (-1.75 V/K) from the OFF-state breakdown voltage (at 1 μA/mm) of AlGaN/GaN HEMTs is due to the trap-assisted tunneling mechanism, which is also well correlated with the conduction mechanism realized from the reverse leakage current of the SBDs.

  1. Correlation of interface states/border traps and threshold voltage shift on AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tian-Li, E-mail: Tian-Li.Wu@imec.be; Groeseneken, Guido [imec, Kapeldreef 75, 3001 Leuven (Belgium); Department of Electrical Engineering, KU Leuven, Leuven (Belgium); Marcon, Denis; De Jaeger, Brice; Lin, H. C.; Franco, Jacopo; Stoffels, Steve; Van Hove, Marleen; Decoutere, Stefaan [imec, Kapeldreef 75, 3001 Leuven (Belgium); Bakeroot, Benoit [imec, Kapeldreef 75, 3001 Leuven (Belgium); Centre for Microsystems Technology, Ghent University, 9052 Gent (Belgium); Roelofs, Robin [ASM, Kapeldreef 75, 3001 Leuven (Belgium)

    2015-08-31

    In this paper, three electrical techniques (frequency dependent conductance analysis, AC transconductance (AC-g{sub m}), and positive gate bias stress) were used to evaluate three different gate dielectrics (Plasma-Enhanced Atomic Layer Deposition Si{sub 3}N{sub 4}, Rapid Thermal Chemical Vapor Deposition Si{sub 3}N{sub 4}, and Atomic Layer Deposition (ALD) Al{sub 2}O{sub 3}) for AlGaN/GaN Metal-Insulator-Semiconductor High-Electron-Mobility Transistors. From these measurements, the interface state density (D{sub it}), the amount of border traps, and the threshold voltage (V{sub TH}) shift during a positive gate bias stress can be obtained. The results show that the V{sub TH} shift during a positive gate bias stress is highly correlated to not only interface states but also border traps in the dielectric. A physical model is proposed describing that electrons can be trapped by both interface states and border traps. Therefore, in order to minimize the V{sub TH} shift during a positive gate bias stress, the gate dielectric needs to have a lower interface state density and less border traps. However, the results also show that the commonly used frequency dependent conductance analysis technique to extract D{sub it} needs to be cautiously used since the resulting value might be influenced by the border traps and, vice versa, i.e., the g{sub m} dispersion commonly attributed to border traps might be influenced by interface states.

  2. Exceeding Conventional Photovoltaic Efficiency Limits Using Colloidal Quantum Dots

    Science.gov (United States)

    Pach, Gregory F.

    Colloidal quantum dots (QDs) are a widely investigated field of research due to their highly tunable nature in which the optical and electronic properties of the nanocrystal can be manipulated by merely changing the nanocrystal's size. Specifically, colloidal quantum dot solar cells (QDSCs) have become a promising candidate for future generation photovoltaic technology. Quantum dots exhibit multiple exciton generation (MEG) in which multiple electron-hole pairs are generated from a single high-energy photon. This process is not observed in bulk-like semiconductors and allows for QDSCs to achieve theoretical efficiency limits above the standard single-junction Shockley-Queisser limit. However, the fast expanding field of QDSC research has lacked standardization of synthetic techniques and device design. Therefore, we sought to detail methodology for synthesizing PbS and PbSe QDs as well as photovoltaic device fabrication techniques as a fast track toward constructing high-performance solar cells. We show that these protocols lead toward consistently achieving efficiencies above 8% for PbS QDSCs. Using the same methodology for building single-junction photovoltaic devices, we incorporated PbS QDs as a bottom cell into a monolithic tandem architecture along with solution-processed CdTe nanocrystals. Modeling shows that near-peak tandem device efficiencies can be achieved across a wide range of bottom cell band gaps, and therefore the highly tunable band gap of lead-chalcogenide QDs lends well towards a bottom cell in a tandem architecture. A fully functioning monolithic tandem device is realized through the development of a ZnTe/ZnO recombination layer that appropriately combines the two subcells in series. Multiple recent reports have shown nanocrystalline heterostructures to undergo the MEG process more efficiency than several other nanostrucutres, namely lead-chalcogenide QDs. The final section of my thesis expands upon a recent publication by Zhang et. al., which

  3. Reducing Parental Uncertainty Around Childhood Cancer: Implementation Decisions and Design Trade-Offs in Developing an Electronic Health Record-Linked Mobile App.

    Science.gov (United States)

    Marsolo, Keith; Shuman, William; Nix, Jeremy; Morrison, Caroline F; Mullins, Larry L; Pai, Ahna Lh

    2017-06-26

    Parents of children newly diagnosed with cancer are confronted with multiple stressors that place them at risk for significant psychological distress. One strategy that has been shown to help reduce uncertainty is the provision of basic information; however, families of newly diagnosed cancer patients are often bombarded with educational material. Technology has the potential to help families manage their informational needs and move towards normalization. The aim of this study was to create a mobile app that pulls together data from both the electronic health record (EHR) and vetted external information resources to provide tailored information to parents of newly diagnosed children as one method to reduce the uncertainty around their child's illness. This app was developed to be used by families in a National Institutes of Health (NIH)-funded randomized controlled trial (RCT) aimed at decreasing uncertainty and the subsequent psychological distress. A 2-phase qualitative study was conducted to elicit the features and content of the mobile app based on the needs and experience of parents of children newly diagnosed with cancer and their providers. Example functions include the ability to view laboratory results, look up appointments, and to access educational material. Educational material was obtained from databases maintained by the National Cancer Institute (NCI) as well as from groups like the Children's Oncology Group (COG) and care teams within Cincinnati Children's Hospital Medical Center (CCHMC). The use of EHR-based Web services was explored to allow data like laboratory results to be retrieved in real-time. The ethnographic design process resulted in a framework that divided the content of the mobile app into the following 4 sections: (1) information about the patient's current treatment and other data from the EHR; (2) educational background material; (3) a calendar to view upcoming appointments at their medical center; and (4) a section where

  4. Study of SiN{sub x}:H{sub y} passivant layers for AlGaN/GaN high electron mobility transistors

    Energy Technology Data Exchange (ETDEWEB)

    Redondo-Cubero, A. [Instituto de Sistemas Optoelectronicos y Microtecnologia and Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Gago, R. [Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Romero, M.F.; Gonzalez-Posada, F.; Brana, A.F.; Munoz, E. [Instituto de Sistemas Optoelectronicos y Microtecnologia and Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Jimenez, A. [Instituto de Sistemas Optoelectronicos y Microtecnologia and Dpto. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, 28040 Madrid (Spain); Dpto. Electronica, Escuela Politecnica, Universidad de Alcala, 28805 Alcala de Henares (Spain)

    2008-07-01

    In this work, hydrogenated silicon nitride (SiN{sub x}:H{sub y}) grown by chemical vapour deposition as passivant layers for high electron mobility transistors (HEMT) have been studied. The film composition and bonding structure were determined by ion beam analysis and X-ray absorption spectroscopy techniques, respectively. The effects of gas precursors (SiH{sub 4}/N{sub 2} and SiH{sub 4}/NH{sub 3}) and film/substrate interface on the film growth have been addressed. The growth on different substrates (Si, GaN, AlGaN), and the effects of plasma pre-treatments have been studied before the growth and the film growth evolution. Results yield no significant differences in all the analysed samples. This points out the relevant role of SiHn radicals as growth precursor species and that intrinsic characteristics of the SiNx:Hy layers are not affected by the film/substrate interface. Hence, improved performance of HEMT with surface plasma pre-treatments before passivation should be related to extrinsic mechanisms (such as creation of defects in AlGaN surface, removal of the surface contamination or ion-induced roughness). (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Mechanism of leakage of ion-implantation isolated AlGaN/GaN MIS-high electron mobility transistors on Si substrate

    Science.gov (United States)

    Zhang, Zhili; Song, Liang; Li, Weiyi; Fu, Kai; Yu, Guohao; Zhang, Xiaodong; Fan, Yaming; Deng, Xuguang; Li, Shuiming; Sun, Shichuang; Li, Xiajun; Yuan, Jie; Sun, Qian; Dong, Zhihua; Cai, Yong; Zhang, Baoshun

    2017-08-01

    In this paper, we systematically investigated the leakage mechanism of the ion-implantation isolated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) on Si substrate. By means of combined DC tests at different temperatures and electric field dependence, we demonstrated the following original results: (1) It is proved that gate leakage is the main contribution to OFF-state leakage of ion-implantation isolated AlGaN/GaN MIS-HEMTs, and the gate leakage path is a series connection of the gate dielectric Si3N4 and Si3N4-GaN interface. (2) The dominant mechanisms of the leakage current through LPCVD-Si3N4 gate dielectric and Si3N4-GaN interface are identified to be Frenkel-Poole emission and two-dimensional variable range hopping (2D-VRH), respectively. (3) A certain temperature annealing could reduce the density of the interface state that produced by ion implantation, and consequently suppress the interface leakage transport, which results in a decrease in OFF-state leakage current of ion-implantation isolated AlGaN/GaN MIS-HEMTs.

  6. High growth rate GaN on 200 mm silicon by metal-organic vapor phase epitaxy for high electron mobility transistors

    Science.gov (United States)

    Charles, M.; Baines, Y.; Bavard, A.; Bouveyron, R.

    2018-02-01

    It is increasingly important to reduce the cycle time of epitaxial growth, in order to reduce the costs of device fabrication, especially for GaN based structures which typically have growth cycles of several hours. We have performed a comprehensive study using metal-organic vapor phase epitaxy (MOVPE) investigating the effects of changing GaN growth rates from 0.9 to 14.5 μm/h. Although there is no significant effect on the strain incorporated in the layers, we have seen changes in the surface morphology which can be related to the change in dislocation behaviour and surface diffusion effects. At the small scale, as seen by AFM, increased dislocation density for higher growth rates leads to increased pinning of growth terraces, resulting in more closely spaced terraces. At a larger scale of hundreds of μm observed by optical profiling, we have related the formation of grains to the rate of surface diffusion of adatoms using a random walk model, implying diffusion distances from 30 μm for the highest growth rates up to 100 μm for the lowest. The increased growth rate also increases the intrinsic carbon incorporation which can increase the breakdown voltage of GaN films. Despite an increased threading dislocation density, these very high growth rates of 14.5 μm/hr by MOVPE have been shown to be appealing for reducing epitaxial growth cycle times and therefore costs in High Electron Mobility Transistor (HEMT) structures.

  7. Combining gas-phase electrophoretic mobility molecular analysis (GEMMA), light scattering, field flow fractionation and cryo electron microscopy in a multidimensional approach to characterize liposomal carrier vesicles.

    Science.gov (United States)

    Urey, Carlos; Weiss, Victor U; Gondikas, Andreas; von der Kammer, Frank; Hofmann, Thilo; Marchetti-Deschmann, Martina; Allmaier, Günter; Marko-Varga, György; Andersson, Roland

    2016-11-20

    For drug delivery, characterization of liposomes regarding size, particle number concentrations, occurrence of low-sized liposome artefacts and drug encapsulation are of importance to understand their pharmacodynamic properties. In our study, we aimed to demonstrate the applicability of nano Electrospray Gas-Phase Electrophoretic Mobility Molecular Analyser (nES GEMMA) as a suitable technique for analyzing these parameters. We measured number-based particle concentrations, identified differences in size between nominally identical liposomal samples, and detected the presence of low-diameter material which yielded bimodal particle size distributions. Subsequently, we compared these findings to dynamic light scattering (DLS) data and results from light scattering experiments coupled to Asymmetric Flow-Field Flow Fractionation (AF4), the latter improving the detectability of smaller particles in polydisperse samples due to a size separation step prior detection. However, the bimodal size distribution could not be detected due to method inherent limitations. In contrast, cryo transmission electron microscopy corroborated nES GEMMA results. Hence, gas-phase electrophoresis proved to be a versatile tool for liposome characterization as it could analyze both vesicle size and size distribution. Finally, a correlation of nES GEMMA results with cell viability experiments was carried out to demonstrate the importance of liposome batch-to-batch control as low-sized sample components possibly impact cell viability. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  8. Temperature Effects on The Electrical Characteristics of In0.15Ga0.85As Pseudomorphic High-Electron-Mobility Transistors

    Directory of Open Access Journals (Sweden)

    BECHLAGHEM Fatima Zohra

    2017-10-01

    Full Text Available Nowadays, GaAs-based HEMTs and pseudomorphic HEMTs are speedily replacing conventional MESFET technology in military and commercial applications including, communication, radar and automotive technologies having need of high gain, and low noise figures especially at millimeter-wave frequencies. In this work, a short gate length pseudomorphic HEMT "p-HEMT" on GaAs substrate is treated. As temperature dependence study is a very important part of the complete characterization on active devices, the impact of temperature variation on the electrical properties of our 30nm short gate length pseudomorphic high-electron mobility In0.15Ga0.85As device is investigated. All our static DC device characteristics and RF response have been obtained using a device simulator that is Silvaco software to examine temperature impact on our device output current, transconductance and cutoff frequency. The 30nm gate pseudomorphic HEMT reported here exhibit superior DC and RF performances, Our results reveals a maximum drain-source current IDS up to 537.16 mA/mm, a peak extrinsic transconductance Gm of 345.4 mS/mm, a cutoff frequency Ft of 285.9 GHz, and a maximum frequency Fmax of 1580 GHz at room temperature.

  9. Analytical derivation of interface state density from sub-threshold swing in AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors

    Science.gov (United States)

    Tokuda, Hirokuni; Asubar, Joel T.; Kuzuhara, Masaaki

    2017-10-01

    We present an analytical expression of sub-threshold swing (SS) in AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs), and describe dependences of SS on structural and relevant material parameters of the MIS-HEMTs. In this work, we derived two different equations where interface states reside at the dielectric/AlGaN interface (proposed equation) and at the AlGaN/GaN interface (conventional equation), which is the customary assumption in the literature. Analysis indicates that SS calculated by using conventional equation is always higher than that calculated by using proposed equation. To confirm the validity of the proposed equation, AlGaN/GaN MIS-HEMTs with and without recess etched gate structure are fabricated and their corresponding interface state densities are derived directly from the measured SS. The MIS-HEMTs with recess show higher SS than those without recess, which is attributed to the increase of interface state density, probably due to the damage introduced during the etching process.

  10. Direct detection of fibrinogen in human plasma using electric-double-layer gated AlGaN/GaN high electron mobility transistors

    Science.gov (United States)

    Regmi, Abiral; Sarangadharan, Indu; Chen, Yen-Wen; Hsu, Chen-Pin; Lee, Geng-Yen; Chyi, Jen-Inn; Shiesh, Shu-Chu; Lee, Gwo-Bin; Wang, Yu-Lin

    2017-08-01

    Fibrinogen found in blood plasma is an important protein biomarker for potentially fatal diseases such as cardiovascular diseases. This study focuses on the development of an assay to detect plasmatic fibrinogen using electrical double layer gated AlGaN/GaN high electron mobility transistor biosensors without complex sample pre-treatment methods used in the traditional assays. The test results in buffer solution and clinical plasma samples show high sensitivity, specificity, and dynamic range. The sensor exhibits an ultra-low detection limit of 0.5 g/l and a detection range of 0.5-4.5 g/l in 1× PBS with 1% BSA. The concentration dependent sensor signal in human serum samples demonstrates the specificity to fibrinogen in a highly dense matrix of background proteins. The sensor does not require complicated automation, and quantitative results are obtained in 5 min with <5 μl sample volume. This sensing technique is ideal for speedy blood based diagnostics such as POC (point of care) tests, homecare tests, or personalized healthcare.

  11. Comparative analysis of nano-scale structural and electrical properties in AlGaN/GaN high electron mobility transistors on SiC and sapphire substrates.

    Science.gov (United States)

    Wang, Cong; Cho, Sung-Jin; Kim, Nam-Young

    2013-10-01

    A comparison of AIGaN/GaN HEMTs fabricated on both 4-in SiC and sapphire substrates was performed. Due to the high crystalline quality with one order lower dislocation density of GaN on a SiC substrate, a better two-dimensional electron gas (2DEG) mobility with high values of drain current density (780 mA/mm) and a better extrinsic transconductance (240 mS/mm) were observed. We demonstrate GaN-on-SiC HEMTs with a periphery gate width of 200 microm, exhibiting a unity-gain cut-off frequency (f(T)) = 29.6 GHz, a maximum frequency of oscillation (f(MAX)) = 63.2 GHz, and an output power density of 6.4 W/mm with a 55% power added efficiency (PAE) at 10 GHz. A surface roughness of 0.828 nm and 1.025 nm and an X-ray diffraction (XRD) GaN (0002) full-width at half-maximum (FWHM) of 120 s and 919 s were measured for the SiC and sapphire-based AIGaN/GaN HEMTs, respectively. The SiC substrate has been shown to be an optimal solution for fabricating HEMTs for X-band high-power applications, which require excellent performances.

  12. Rapid detection of cardiac troponin I using antibody-immobilized gate-pulsed AlGaN/GaN high electron mobility transistor structures

    Science.gov (United States)

    Yang, Jiancheng; Carey, Patrick; Ren, Fan; Wang, Yu-Lin; Good, Michael L.; Jang, Soohwan; Mastro, Michael A.; Pearton, S. J.

    2017-11-01

    We report a comparison of two different approaches to detecting cardiac troponin I (cTnI) using antibody-functionalized AlGaN/GaN High Electron Mobility Transistors (HEMTs). If the solution containing the biomarker has high ionic strength, there can be difficulty in detection due to charge-screening effects. To overcome this, in the first approach, we used a recently developed method involving pulsed biases applied between a separate functionalized electrode and the gate of the HEMT. The resulting electrical double layer produces charge changes which are correlated with the concentration of the cTnI biomarker. The second approach fabricates the sensing area on a glass slide, and the pulsed gate signal is externally connected to the nitride HEMT. This produces a larger integrated change in charge and can be used over a broader range of concentrations without suffering from charge-screening effects. Both approaches can detect cTnI at levels down to 0.01 ng/ml. The glass slide approach is attractive for inexpensive cartridge-type sensors.

  13. Breakdown mechanism in AlGaN/GaN high-electron mobility transistor structure on free-standing n-type GaN substrate

    Science.gov (United States)

    Tanabe, Shinichi; Watanabe, Noriyuki; Matsuzaki, Hideaki

    2016-05-01

    The breakdown mechanism in a high-electron mobility transistor structure on free-standing n-type GaN substrates consisting of a C-doped GaN layer as a high-resistivity buffer was investigated with a two-terminal vertical device that has a C-doped GaN buffer between electrodes. Initially, current density increases with the square of bias voltage. This is then followed by an abrupt increase by several orders of magnitude within ten volts, which results in breakdown. These behaviors are consistent with the theory of the space-charge limited current. In this theory, current density increases steeply when trap sites at a certain energy level are completely filled with injected carriers. These results indicate that the existence of trap levels in the C-doped GaN layer is one of the possible factors that determine the breakdown. The trap density and trap level of the C-doped GaN layer were also evaluated.

  14. Room-temperature mobility above 2200 cm{sup 2}/V·s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jr-Tai, E-mail: jrche@ifm.liu.se; Persson, Ingemar; Nilsson, Daniel; Hsu, Chih-Wei; Palisaitis, Justinas; Forsberg, Urban; Persson, Per O. Å.; Janzén, Erik [Department of Physics, Chemistry, and Biology, Linköping University, SE 581 83 Linköping (Sweden)

    2015-06-22

    A high mobility of 2250 cm{sup 2}/V·s of a two-dimensional electron gas (2DEG) in a metalorganic chemical vapor deposition-grown AlGaN/GaN heterostructure was demonstrated. The mobility enhancement was a result of better electron confinement due to a sharp AlGaN/GaN interface, as confirmed by scanning transmission electron microscopy analysis, not owing to the formation of a traditional thin AlN exclusion layer. Moreover, we found that the electron mobility in the sharp-interface heterostructures can sustain above 2000 cm{sup 2}/V·s for a wide range of 2DEG densities. Finally, it is promising that the sharp-interface AlGaN/GaN heterostructure would enable low contact resistance fabrication, less impurity-related scattering, and trapping than the AlGaN/AlN/GaN heterostructure, as the high-impurity-contained AlN is removed.

  15. Exceeding the solar cell Shockley-Queisser limit via thermal up-conversion of low-energy photons

    CERN Document Server

    Boriskina, Svetlana V

    2013-01-01

    Maximum efficiency of ideal single-junction photovoltaic (PV) cells is limited to 33% (for one sun illumination) by intrinsic losses such as band edge thermalization, radiative recombination, and inability to absorb below-bandgap photons. This intrinsic thermodynamic limit, named after Shockley and Queisser (S-Q), can be exceeded by utilizing low-energy photons either via their electronic up-conversion or via thermophotovoltaic (TPV) conversion process. However, electronic up-conversion systems have extremely low efficiencies, and practical temperature considerations limit the operation of TPV converters to the narrow-gap PV cells. Here we develop a conceptual design of a hybrid TPV platform, which exploits thermal up-conversion of low-energy photons and is compatible with conventional silicon PV cells by using spectral and directional selectivity of the up-converter. The hybrid platform offers sunlight-to-electricity conversion efficiency exceeding that imposed by the S-Q limit on the corresponding PV cells ...

  16. Mobile Learning Using Mobile Phones

    Science.gov (United States)

    Vicente, Paula

    2013-01-01

    The participation in mobile learning programs is conditioned by having/using mobile communication technology. Those who do not have or use such technology cannot participate in mobile learning programs. This study evaluates who are the most likely participants of mobile learning programs by examining the demographic profile and mobile phone usage…

  17. High mobility solution-processed hybrid light emitting transistors

    Science.gov (United States)

    Walker, Bright; Ullah, Mujeeb; Chae, Gil Jo; Burn, Paul L.; Cho, Shinuk; Kim, Jin Young; Namdas, Ebinazar B.; Seo, Jung Hwa

    2014-11-01

    We report the design, fabrication, and characterization of high-performance, solution-processed hybrid (inorganic-organic) light emitting transistors (HLETs). The devices employ a high-mobility, solution-processed cadmium sulfide layer as the switching and transport layer, with a conjugated polymer Super Yellow as an emissive material in non-planar source/drain transistor geometry. We demonstrate HLETs with electron mobilities of up to 19.5 cm2/V s, current on/off ratios of >107, and external quantum efficiency of 10-2% at 2100 cd/m2. These combined optical and electrical performance exceed those reported to date for HLETs. Furthermore, we provide full analysis of charge injection, charge transport, and recombination mechanism of the HLETs. The high brightness coupled with a high on/off ratio and low-cost solution processing makes this type of hybrid device attractive from a manufacturing perspective.

  18. 41 CFR 301-11.305 - What if my actual expenses exceed the 300 percent ceiling?

    Science.gov (United States)

    2010-07-01

    ... expenses exceed the 300 percent ceiling? 301-11.305 Section 301-11.305 Public Contracts and Property... ceiling? Your reimbursement is limited to the 300 percent ceiling. There is no authority to exceed this ceiling. ...

  19. Aluminum gallium nitride (GaN)/GaN high electron mobility transistor-based sensors for glucose detection in exhaled breath condensate.

    Science.gov (United States)

    Chu, Byung Hwan; Kang, Byoung Sam; Hung, Sheng Chun; Chen, Ke Hung; Ren, Fan; Sciullo, Andrew; Gila, Brent P; Pearton, Stephen J

    2010-01-01

    Immobilized aluminum gallium nitride (AlGaN)/GaN high electron mobility transistors (HEMTs) have shown great potential in the areas of pH, chloride ion, and glucose detection in exhaled breath condensate (EBC). HEMT sensors can be integrated into a wireless data transmission system that allows for remote monitoring. This technology offers the possibility of using AlGaN/GaN HEMTs for extended investigations of airway pathology of detecting glucose in EBC without the need for clinical visits. HEMT structures, consisting of a 3-microm-thick undoped GaN buffer, 30-A-thick Al(0.3)Ga(0.7)N spacer, and 220-A-thick silicon-doped Al(0.3)Ga(0.7)N cap layer, were used for fabricating the HEMT sensors. The gate area of the pH, chloride ion, and glucose detection was immobilized with scandium oxide (Sc(2)O(3)), silver chloride (AgCl) thin film, and zinc oxide (ZnO) nanorods, respectively. The Sc(2)O(3)-gated sensor could detect the pH of solutions ranging from 3 to 10 with a resolution of approximately 0.1 pH. A chloride ion detection limit of 10(-8) M was achieved with a HEMT sensor immobilized with the AgCl thin film. The drain-source current of the ZnO nanorod-gated AlGaN/GaN HEMT sensor immobilized with glucose oxidase showed a rapid response of less than 5 seconds when the sensor was exposed to the target glucose in a buffer with a pH value of 7.4. The sensor could detect a wide range of concentrations from 0.5 nM to 125 microM. There is great promise for using HEMT-based sensors to enhance the detection sensitivity for glucose detection in EBC. Depending on the immobilized material, HEMT-based sensors can be used for sensing different materials. These electronic detection approaches with rapid response and good repeatability show potential for the investigation of airway pathology. The devices can also be integrated into a wireless data transmission system for remote monitoring applications. This sensor technology could use the exhaled breath condensate to measure the

  20. Spin dephasing and photoinduced spin diffusion in a high-mobility two-dimensional electron system embedded in a GaAs-(Al,Ga)As quantum well grown in the [110] direction

    Science.gov (United States)

    Völkl, R.; Griesbeck, M.; Tarasenko, S. A.; Schuh, D.; Wegscheider, W.; Schüller, C.; Korn, T.

    2011-06-01

    We have studied spin dephasing and spin diffusion in a high-mobility two-dimensional electron system, embedded in a GaAs/AlGaAs quantum well grown in the [110] direction, by a two-beam Hanle experiment. For very low excitation density, we observe spin lifetimes of more than 16 ns, which rapidly decrease as the pump intensity is increased. Two mechanisms contribute to this decrease: The optical excitation produces holes, which lead to a decay of electron spin via the Bir-Aronov-Pikus mechanism and recombination with spin-polarized electrons. By scanning the distance between the pump and probe beams, we observe the diffusion of spin-polarized electrons over more than 20 μm. For high pump intensity, the spin polarization in a distance of several micrometers from the pump beam is larger than at the pump spot, due to the reduced influence of photogenerated holes.

  1. Electronic spin storage in an electrically readable nuclear spin memory with a lifetime >100 seconds.

    Science.gov (United States)

    McCamey, D R; Van Tol, J; Morley, G W; Boehme, C

    2010-12-17

    Electron spins are strong candidates with which to implement spintronics because they are both mobile and able to be manipulated. The relatively short lifetimes of electron spins, however, present a problem for the long-term storage of spin information. We demonstrated an ensemble nuclear spin memory in phosphorous-doped silicon, which can be read out electrically and has a lifetime exceeding 100 seconds. The electronic spin information can be mapped onto and stored in the nuclear spin of the phosphorus donors, and the nuclear spins can then be repetitively read out electrically for time periods that exceed the electron spin lifetime. We discuss how this memory can be used in conjunction with other silicon spintronic devices.

  2. The Costs of Web Advertisements while Mobile Browsing

    NARCIS (Netherlands)

    van den Brande, Jeffrey; Pras, Aiko

    Tablet PCs, iPads and mobile phones all include facilities to browse the mobile Internet. The costs of mobile Internet access may become extraordinary, however, when the data limit is exceeded or when the user is roaming abroad without a roaming data plan. Since users may see advertisements as

  3. Efficacy and External Validity of Electronic and Mobile Phone-Based Interventions Promoting Vegetable Intake in Young Adults: Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Nour, Monica; Chen, Juliana; Allman-Farinelli, Margaret

    2016-04-08

    Young adults (18-35 years) remain among the lowest vegetable consumers in many western countries. The digital era offers opportunities to engage this age group in interventions in new and appealing ways. This systematic review evaluated the efficacy and external validity of electronic (eHealth) and mobile phone (mHealth) -based interventions that promote vegetable intake in young adults. We searched several electronic databases for studies published between 1990 and 2015, and 2 independent authors reviewed the quality and risk of bias of the eligible papers and extracted data for analyses. The primary outcome of interest was the change in vegetable intake postintervention. Where possible, we calculated effect sizes (Cohen d and 95% CIs) for comparison. A random effects model was applied to the data for meta-analysis. Reach and representativeness of participants, intervention implementation, and program maintenance were assessed to establish external validity. Published validation studies were consulted to determine the validity of tools used to measure intake. We applied the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system to evaluate the overall quality of the body of evidence. Of the 14 studies that met the selection criteria, we included 12 in the meta-analysis. In the meta-analysis, 7 studies found positive effects postintervention for fruit and vegetable intake, Cohen d 0.14-0.56 (pooled effect size 0.22, 95% CI 0.11-0.33, I(2)=68.5%, P=.002), and 4 recorded positive effects on vegetable intake alone, Cohen d 0.11-0.40 (pooled effect size 0.15, 95% CI 0.04-0.28, I(2)=31.4%, P=.2). These findings should be interpreted with caution due to variability in intervention design and outcome measures. With the majority of outcomes documented as a change in combined fruit and vegetable intake, it was difficult to determine intervention effects on vegetable consumption specifically. Measurement of intake was most commonly by self

  4. Mobile user experience for voice services: A theoretical framework

    CSIR Research Space (South Africa)

    Botha, Adèle

    2012-02-01

    Full Text Available . Oinas-Kukkonen, H. Mobile Electronic Commerce through the Web. in Second International Conference on Telecommunication and Electronic Commerce (ICTEC '99). 1999. Nashville, TN, USA. 15. Oinas-Kukkonen, H. and V. Kurkela, Developing Successful Mobile...

  5. Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy

    Science.gov (United States)

    Schütz, P.; Christensen, D. V.; Borisov, V.; Pfaff, F.; Scheiderer, P.; Dudy, L.; Zapf, M.; Gabel, J.; Chen, Y. Z.; Pryds, N.; Rogalev, V. A.; Strocov, V. N.; Schlueter, C.; Lee, T.-L.; Jeschke, H. O.; Valentí, R.; Sing, M.; Claessen, R.

    2017-10-01

    The spinel/perovskite heterointerface γ -Al2O3/SrTiO3 hosts a two-dimensional electron system (2DES) with electron mobilities exceeding those in its all-perovskite counterpart LaAlO3/SrTiO3 by more than an order of magnitude, despite the abundance of oxygen vacancies which act as electron donors as well as scattering sites. By means of resonant soft x-ray photoemission spectroscopy and ab initio calculations, we reveal the presence of a sharply localized type of oxygen vacancies at the very interface due to the local breaking of the perovskite symmetry. We explain the extraordinarily high mobilities by reduced scattering resulting from the preferential formation of interfacial oxygen vacancies and spatial separation of the resulting 2DES in deeper SrTiO3 layers. Our findings comply with transport studies and pave the way towards defect engineering at interfaces of oxides with different crystal structures.

  6. Dosimetric characteristics of electron beams produced by two mobile accelerators, Novac7 and Liac, for intraoperative radiation therapy through Monte Carlo simulation

    National Research Council Canada - National Science Library

    Righi, Sergio; Karaj, Evis; Felici, Giuseppe; Di Martino, Fabio

    2013-01-01

    ...), which produce high energy, very high dose‐per‐pulse electron beams. The characteristics of the accelerators heads of the Novac7 and Liac are different compared to conventional electron accelerators...

  7. Mobile payment

    CERN Document Server

    Lerner, Thomas

    2013-01-01

    Paying with mobile devices such as mobile phones or smart phones will expand worldwide in the coming years. This development provides opportunities for various industries (banking, telecommunications, credit card business, manufacturers, suppliers, retail) and for consumers.

  8. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2015-01-01

    Mobile phones are ubiquitous and have completely transformed the way we live, work, learn and conduct our everyday activities. Mobile phones have also changed the way users access lexicographic data. In fact, it can be argued that mobile phones and lexicography are not yet compatible. Modern users...... are already mobile – but lexicography is not yet fully ready for the mobile challenge, mobile users and mobile user situations. The article is based on empirical data from two surveys comprising 10 medical doctors, who were asked to look up five medical substances with the medical dictionary app Medicin...... and that lexicographic innovation is needed. A new type of users, new user situations and new access methods call for new lexicographic solutions, and this article proposes a six-pointed hexagram model, which can be used during dictionary app design to lexicographically calibrate the six dimensions in mobile...

  9. Infrared ellipsometry study of the confined electrons in a high-mobility γ-Al2O3/SrTiO3 heterostructure

    DEFF Research Database (Denmark)

    Yazdi-Rizi, M.; Marsik, P.; Mallett, B. P. P.

    2016-01-01

    of SrTiO3, we derive the sheet carrier density, Ns, the mobility, μ, and the depth profile of the carrier concentration. Notably, we find that Ns and the shape of the depth profile are similar as in LaAlO3/SrTiO3 (LAO/STO) heterostructures for which the itinerant carriers are believed to arise from...... a polar discontinuity. Despite an order of magnitude higher mobility in GAO/STO, as obtained from transport measurements, the derived mobility in the infrared range exhibits only a twofold increase. We interpret this finding in terms of the polaronic nature of the confined charge carriers in GAO....../STO and LAO/STO which leads to a strong, frequency-dependent interaction with the STO phonons....

  10. Mobile marketing

    OpenAIRE

    Klečková, Zuzana

    2013-01-01

    The main aim of this thesis was to provide a comprehensive overview of the mobile marketing and analyze selected campaigns of Czech mobile marketing in comparison to world successful campaigns. The research contained studying of available literature about the theme to gain general knowledge about the issue. The theoretical part of the thesis contains predominantly various definitions of mobile marketing and its tools, advantages of these tools and some information about Mobile Marketing Assoc...

  11. Mobile Lexicography

    DEFF Research Database (Denmark)

    Køhler Simonsen, Henrik

    2014-01-01

    Users are already mobile, but the question is to which extent knowledge-based dictionary apps are designed for the mobile user situation. The objective of this article is to analyse the characteristics of the mobile user situation and to look further into the stationary user situation...

  12. Staging Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    and lived as people are “staging themselves” (from below). Staging mobilities is a dynamic process between “being staged” (for example, being stopped at traffic lights) and the “mobile staging” of interacting individuals (negotiating a passage on the pavement). Staging Mobilities is about the fact...

  13. Telehealth and Mobile Health

    OpenAIRE

    Ward, Tomas

    2015-01-01

    The E-Medicine, E-Health, M-Health, Telemedicine, and Telehealth Handbook provides extensive coverage of modern telecommunication in the medical industry, from sensors on and within the body to electronic medical records and beyond. Telehealth and Mobile Health is the second volume of this handbook. Featuring chapters written by leading experts and researchers in their respective fields.

  14. The Effectiveness of Intervention on the Behavior of Individuals with Autism: A Meta-Analysis Using Percentage of Data Points Exceeding the Median of Baseline Phase (PEM)

    Science.gov (United States)

    Ma, Hsen-Hsing

    2009-01-01

    The aim of the present study is to demonstrate the percentage of data points exceeding the median of baseline phase (PEM) approach using data on autism treatment for illustrative purposes to compare the effectiveness of different interventions on the problem behaviors of individuals with autism. Electronic databases such as The ProQuest and Google…

  15. Mobile Probes in Mobile Learning

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Blomhøj, Ulla; Duvaa, Uffe

    In this paper experiences from using mobile probes in educational design of a mobile learning application is presented. The probing process stems from the cultural probe method, and was influenced by qualitative interview and inquiry approaches. In the project, the mobile phone was not only acting...... as an agent for acquiring empirical data (as the situation in hitherto mobile probe settings) but was also the technological medium for which data should say something about (mobile learning). Consequently, not only the content of the data but also the ways in which data was delivered and handled, provided...... a valuable dimension for investigating mobile use. The data was collected at the same time as design activities took place and the collective data was analysed based on user experience goals and cognitive processes from interaction design and mobile learning. The mobile probe increased the knowledge base...

  16. Monitoring dietary intake and physical activity electronically: Feasibility, usability, and ecological validity of a mobile-based ecological momentary assessment tool

    NARCIS (Netherlands)

    Spook, J.E.; Paulussen, T.; Kok, G.; Empelen, P. van

    2013-01-01

    Background: Despite the growing body of research on complex lifestyle behaviors (eg, Dietary Intake [DI] and Physical Activity [PA]), monitoring of these behaviors has been hampered by a lack of suitable methods. A possible solution to this deficiency is mobile-based Ecological Momentary Assessment

  17. High Electron Mobility and Ambient Stability in Solution-Processed Perylene-Based Organic Field-Effect Transistors : origin of the enhanced electrical performances

    NARCIS (Netherlands)

    Piliego, Claudia; Jarzab, Dorota; Gigli, Giuseppe; Chen, Zhihua; Facchetti, Antonio; Loi, Maria Antonietto

    2009-01-01

    Bottom-contact n-channel OFETs basedon spin-coated films of N,N'-1H,1H-perfluorobutyl dicyanoperylenediimide (PDI-FCN(2)) exhibit a saturation-regime mobility of 0.15 cm(2) V(-1) s(-1) in vacuum and good air stability. These performances are attributed to the high crystallinity and to the edge-on

  18. The effect of employing knowledge workers from technologically advanced countries: The knowledge spillover caused by the mobility of knowledge workers in electronic industries in Asia

    Directory of Open Access Journals (Sweden)

    Ayano Fujiwara

    2017-08-01

    Full Text Available This paper is an extension of work originally presented in 2017 6th International Conference on Industrial Technology and Management (ICITM [53]. This research focuses on the mobilization of human resources in the Asian electrical industry and analyzes the impact of engineers’ international mobility on the innovation of enterprises in the host countries. I examine the characteristics of engineers who moved from Japan to China and South Korea to explore which types of engineers successful firms in China and South Korea select from rival companies in Japan. In addition, this study focuses on the role of the inventors’ networks to investigate the significance of researcher mobility and knowledge spillover as mechanisms that facilitate the flow of tacit knowledge. This study reveals that during the process of innovation, informal networks play an important role in the mobility of engineers. The findings suggest that successful firms require people with analytical skills and problem-solving capacity, not “star inventors.”

  19. Prediction in Partial Duration Series With Generalized Pareto-Distributed Exceedances

    DEFF Research Database (Denmark)

    Rosbjerg, Dan; Madsen, Henrik; Rasmussen, Peter Funder

    1992-01-01

    As a generalization of the common assumption of exponential distribution of the exceedances in Partial duration series the generalized Pareto distribution has been adopted. Estimators for the parameters are presented using estimation by both method of moments and probability-weighted moments......-weighted moments. Maintaining the generalized Pareto distribution as the parent exceedance distribution the T-year event is estimated assuming the exceedances to be exponentially distributed. For moderately long-tailed exceedance distributions and small to moderate sample sizes it is found, by comparing mean...... square errors of the T-year event estimators, that the exponential distribution is preferable to the correct generalized Pareto distribution despite the introduced model error and despite a possible rejection of the exponential hypothesis by a test of significance. For moderately short-tailed exceedance...

  20. Theoretical analysis of the mobility of two-dimensional electron gas in the quaternary AlxInyGa1-x-yN/GaN heterojunctions limited by the alloy composition fluctuation

    Science.gov (United States)

    Li, Yao; Zhang, Jinfeng; Liu, Guipeng; Quan, Rudai; Duan, Xiaoling; Zhang, Jincheng; Hao, Yue

    2017-10-01

    We established the model of the electron mobility limited by the alloy composition fluctuation scattering in the quaternary AlxInyGa1-x-yN/GaN heterojunctions for the first time. The alloy composition fluctuation along the AlxInyGa1-x-yN/GaN heterointerface was considered and characterized by the lateral correlation length L, and the fluctuations of aluminum and indium mole fractions (Δx and Δy) independent to each other. The situation of alloy composition fluctuation is investigated in the following cases. Only x or y fluctuates, and both x and y fluctuate with equal/unequal amplitudes in the same/opposite direction. We find that the scattering with both x and y fluctuating in the same direction is the weakest, while x and y fluctuating in the opposite directions leads to the strongest scattering. This in nature stems from the disparity of the bandgap and polarization in AlInN, AlGaN and GaN. The effects of different parameters, such as x and y, Δx and Δy, L, and the thickness of AlxInyGa1-x-yN barrier layer d on the mobility are also studied. The model will in principle give a universal explanation to the effect of alloy composition fluctuation scattering on the carrier mobility in the GaN-based heterostructures with ternary or quaternary alloy barrier layers.

  1. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix

    Contemporary society is marked and defined by the ways in which mobile goods, bodies, vehicles, objects, and data are organized, moved and staged. On the background of the ‘mobilities turn’ (e.g. Cresswell 2006, Urry 2007) this book articulates a new and emerging research field, namely that of ‘m......Contemporary society is marked and defined by the ways in which mobile goods, bodies, vehicles, objects, and data are organized, moved and staged. On the background of the ‘mobilities turn’ (e.g. Cresswell 2006, Urry 2007) this book articulates a new and emerging research field, namely...... that of ‘mobilities design’. The book revolves around the following research question: How are design decisions and interventions staging mobilities? It builds upon the Staging Mobilities model (Jensen 2013) in an explorative inquiry into the problems and potentials of the design of mobilities. The exchange value...... between mobilities and design research is twofold. To mobilities research this means getting closer to the ‘material’, and to engage in the creative, explorative and experimental approaches of the design world which offer new potentials for innovative research. Design research, on the other hand, might...

  2. High electron mobility and low carrier concentration of hydrothermally grown ZnO thin films on seeded a-plane sapphire at low temperature

    Science.gov (United States)

    Jayah, Nurul Azzyaty; Yahaya, Hafizal; Mahmood, Mohamad Rusop; Terasako, Tomoaki; Yasui, Kanji; Hashim, Abdul Manaf

    2015-01-01

    Hydrothermal zinc oxide (ZnO) thick films were successfully grown on the chemical vapor deposition (CVD)-grown thick ZnO seed layers on a-plane sapphire substrates using the aqueous solution of zinc nitrate dehydrate (Zn(NO3)2). The use of the CVD ZnO seed layers with the flat surfaces seems to be a key technique for obtaining thick films instead of vertically aligned nanostructures as reported in many literatures. All the hydrothermal ZnO layers showed the large grains with hexagonal end facets and were highly oriented towards the c-axis direction. Photoluminescence (PL) spectra of the hydrothermal layers were composed of the ultraviolet (UV) emission (370 to 380 nm) and the visible emission (481 to 491 nm), and the intensity ratio of the former emission ( I UV) to the latter emission ( I VIS) changed, depending on both the molarity of the solution and temperature. It is surprising that all the Hall mobilities for the hydrothermal ZnO layers were significantly larger than those for their corresponding CVD seed films. It was also found that, for the hydrothermal films grown at 70°C to 90°C, the molarity dependences of I UV/ I VIS resembled those of mobilities, implying that the mobility in the film is affected by the structural defects. The highest mobility of 166 cm2/Vs was achieved on the hydrothermal film with the carrier concentration of 1.65 × 1017 cm-3 grown from the aqueous solution of 40 mM at 70°C.

  3. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix

    2016-01-01

    of increasing concern and societal importance, regardless if the focus is on new inequalities, environmental sustainability, or the meaning of vernacular mobilities design to the everyday life. The theme of ‘mobilities design’ opens up the agenda of architectural research into infrastructure spaces as ‘spaces...... of the perspective in the direction of a material and design oriented turn. In order to fulfill this purpose we articulate a new and emerging research field, namely that of ‘mobilities design’. In our understanding time has come to articulate ‘Mobilities Design’ as a dedicated research field in and of its own....... There is a need for research targeting the material, physical and design-oriented dimensions of the multiple mobilities from the local to the global. Despite its cross-disciplinary identity the ‘mobilities turn’ has not sufficiently capitalized from the potential in exploring issues of material design...

  4. Mobility Divides

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    Contemporary mobilities are cultural and social manifestations, and the mobile practices in the everyday life of billions of humans are re-configuring senses of place, self, other and relationships to the built environment. The way ‘mobile situations’ are staged in designed and built environments......’ in the everyday life and cast light on how design and ‘materialities of mobilites’ are creating differential mobilities across societies, social networks, and communities of practices....... are increasingly becoming ‘second nature’ but also expressions of power, exclusion, and difference. In this talk I will be applying a perspective of ‘mobile situationism’ illustrating how mobile everyday life practices are staged ‘from above’ in planning and policy frameworks, design codes and architectural...

  5. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix; Wind, Simon

    2016-01-01

    In this paper, we identify the nexus between design (architecture, urban design, service design, etc.) and mobilities as a new and emerging research field. In this paper, we apply a “situational mobilities” perspective and take point of departure in the pragmatist question: “What design decisions...... and interventions affords this particular mobile situation?” The paper presents the contours of an emerging research agenda within mobilities research. The advent of “mobilities design” as an emerging research field points towards a critical interest in the material as well as practical consequences of contemporary......-making. The paper proposes that increased understanding of the material affordances facilitated through design provides important insight to planning and policymaking that at times might be in risk of becoming too detached from the everyday life of the mobile subject within contemporary mobilities landscapes....

  6. Mobilities Design

    DEFF Research Database (Denmark)

    Lanng, Ditte Bendix; Wind, Simon; Jensen, Ole B.

    2017-01-01

    is a relevant field of knowledge for urban design, because of its focus on a nuanced conceptualization of the daily journeys that we all undertake in mobilities spaces. Second, the mobilities turn aids a theoretical “mobilization” of the design of mobilities spaces with a point of departure in a fused theory...... field with particular attention to actor-network theory (ANT), which offers tools to understand the embeddedness of mobilities spaces in hybrid and dynamic relationships. Through these linkages between the mobilities turn and urban design, the article suggests a pathway for a carefully radical...... for urban designers and architects to address mobilities spaces in relation not only to technical demands, but also to the wide host of social, cultural, political, economic, and affective formations in which they are embedded and which they influence....

  7. Mobility Work

    DEFF Research Database (Denmark)

    Bardram, Jakob Eyvind; Bossen, Claus

    2005-01-01

    We posit the concept of Mobility Work to describe efforts of moving about people and things as part of accomplishing tasks. Mobility work can be seen as a spatial parallel to the concept of articulation work proposed by the sociologist Anselm Strauss. Articulation work describes efforts...... of coordination necessary in cooperative work, but focuses, we argue, mainly on the temporal aspects of cooperative work. As a supplement, the concept of mobility work focuses on the spatial aspects of cooperative work. Whereas actors seek to diminish the amount of articulation work needed in collaboration...... by constructing Standard Operation Procedures (SOPs), actors minimise mobility work by constructing Standard Operation Configurations (SOCs). We apply the concept of mobility work to the ethnography of hospital work, and argue that mobility arises because of the need to get access to people, places, knowledge and...

  8. Monolithic distributed Bragg reflector cavities in Al2O3 with quality factors exceeding one million

    NARCIS (Netherlands)

    Bernhardi, Edward; van Wolferen, Hendricus A.G.M.; Worhoff, Kerstin; de Ridder, R.M.; Pollnau, Markus

    Monolithic distributed Bragg reflector (DBR) cavities with quality factors exceeding one million have been realized in aluminum oxide channel waveguides. This technology enabled the successful demonstration of the first DBR laser in this waveguide platform.

  9. A lower bound on the probability that a binomial random variable is exceeding its mean

    OpenAIRE

    Pelekis, Christos; Ramon, Jan

    2016-01-01

    We provide a lower bound on the probability that a binomial random variable is exceeding its mean. Our proof employs estimates on the mean absolute deviation and the tail conditional expectation of binomial random variables.

  10. Mobile Semiotics

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    2013-01-01

    is a ‘mobile sense making’ where signs and materially situated meanings connect to the moving human body and thus create particular challenges and complexities of making sense of the world. The chapter includes notions of mobility systems and socio-technical networks in order to show how a ‘semiotic layer’ may......This chapter aims to understand the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The chapter explores the potentials of semiotics and its relationship to the new mobilities literature. What takes place...

  11. Electronic Warfare Signature Measurement Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Electronic Warfare Signature Measurement Facility contains specialized mobile spectral, radiometric, and imaging measurement systems to characterize ultraviolet,...

  12. Conduction Mechanisms at Interface of AlN/SiN Dielectric Stacks with AlGaN/GaN Heterostructures for Normally-off High Electron Mobility Transistors: Correlating Device Behavior with Nanoscale Interfaces Properties.

    Science.gov (United States)

    Greco, Giuseppe; Fiorenza, Patrick; Iucolano, Ferdinando; Severino, Andrea; Giannazzo, Filippo; Roccaforte, Fabrizio

    2017-10-11

    In this work, the conduction mechanisms at the interface of AlN/SiN dielectric stacks with AlGaN/GaN heterostructures have been studied combining different macroscopic and nanoscale characterizations on bare materials and devices. The AlN/SiN stacks grown on the recessed region of AlGaN/GaN heterostructures have been used as gate dielectric of hybrid metal-insulator-semiconductor high electron mobility transistors (MISHEMTs), showing a normally-off behavior (V th = +1.2 V), high channel mobility (204 cm 2 V -1 s -1 ), and very good switching behavior (I ON /I OFF current ratio of (5-6) × 10 8 and subthreshold swing of 90 mV/dec). However, the transistors were found to suffer from a positive shift of the threshold voltage during subsequent bias sweeps, which indicates electron trapping in the dielectric stack. To get a complete understanding of the conduction mechanisms and of the charge trapping phenomena in AlN/SiN films, nanoscale current and capacitance measurements by conductive atomic force microscopy (C-AFM) and scanning capacitance microscopy (SCM) have been compared with a macroscopic temperature-dependent characterization of gate current in MIS capacitors. The nanoscale electrical analyses showed the presence of a spatially uniform distribution of electrons trapping states in the insulator and the occurrence of a density of 7 × 10 8 cm -2 of local and isolated current spots at high bias values. These nanoscale conductive paths can be associated with electrically active defects responsible for the trap-assisted current transport mechanism through the dielectric, observed by the temperature-dependent characterization of the gate current. The results of this study can be relevant for future applications of AlN/SiN bilayers in GaN hybrid MISHEMT technology.

  13. A Survey on Mobile Payment Systems Security

    OpenAIRE

    Leila Esmaeili; Zeinab Borhani-Fard; Mohammad Ali Arasteh

    2012-01-01

    In recent years, increasing use of mobile devices and the emergence of new technologies have changed mobile commerce and mobile payment in all over the world. Although many attempts have been made to implement secure mobile payment systems and services, growing forgery, fraud and other related electronic crimes as well as security attacks and threats prove the necessity of paying special attention to security issues for development and extension of such systems. In this paper, we investigate ...

  14. Mobile Semiotics - signs and mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    This paper is about how to comprehend the mobile condition of contemporary life with a particular view to the signifying dimension of the environment and its ‘readability’. The paper explores the potentials of semiotics and its relationship to the new mobilities literature. The theoretical scope...... is therefore an attempt to mobilize semiotics by drawing on a central body of theory within and adjacent to the discipline. For instance the founding works of C. S. Peirce will be related to the contemporary notions of ‘geosemiotics’ by Scollon & Scollon. The paper’s theoretical claim is that semiotics hold...... a potential for mobilities studies if the awareness of seeing the environment as a semiotic layer and system can be sensitized to the insights of the ‘mobilities turn’. Empirically the paper tentatively explores the usefulness of a mobile semiotics approach to cases such as street signage, airport design...

  15. Mobile phones and mobile communication

    DEFF Research Database (Denmark)

    Ling, Richard; Donner, Jonathan

    With staggering swiftness, the mobile phone has become a fixture of daily life in almost every society on earth. In 2007, the world had over 3 billion mobile subscriptions. Prosperous nations boast of having more subscriptions than people. In the developing world, hundreds of millions of people who...... could never afford a landline telephone now have a mobile number of their own. With a mobile in our hand many of us feel safer, more productive, and more connected to loved ones, but perhaps also more distracted and less involved with things happening immediately around us. Written by two leading...... researchers in the field, this volume presents an overview of the mobile telephone as a social and cultural phenomenon. Research is summarized and made accessible though detailed descriptions of ten mobile users from around the world. These illustrate popular debates, as well as deeper social forces at work...

  16. Secure Architectures for Mobile Applications

    Directory of Open Access Journals (Sweden)

    2007-01-01

    Full Text Available The paper presents security issues and architectures for mobile applications and GSM infrastructure. The article also introduces the idea of a new secure architecture for an inter-sector electronic wallet used in payments - STP4EW (Secure Transmission Protocol for Electronic Wallet

  17. Resource Mobilization

    International Development Research Centre (IDRC) Digital Library (Canada)

    This practical guidebook supports and promotes new and creative thinking on resource mobilization for ... sources and come up with creative resource mobilization strategies to ensure survival. The Importance of ...... funds had already been earmarked for buying new classroom facilities. Maintain integrity of auction. 2.

  18. Analysis of the factors influencing healthcare professionals' adoption of mobile electronic medical record (EMR) using the unified theory of acceptance and use of technology (UTAUT) in a tertiary hospital.

    Science.gov (United States)

    Kim, Seok; Lee, Kee-Hyuck; Hwang, Hee; Yoo, Sooyoung

    2016-01-30

    Although the factors that affect the end-user's intention to use a new system and technology have been researched, the previous studies have been theoretical and do not verify the factors that affected the adoption of a new system. Thus, this study aimed to confirm the factors that influence users' intentions to utilize a mobile electronic health records (EMR) system using both a questionnaire survey and a log file analysis that represented the real use of the system. After observing the operation of a mobile EMR system in a tertiary university hospital for seven months, we performed an offline survey regarding the user acceptance of the system based on the Unified Theory of Acceptance and Use of Technology (UTAUT) and the Technology Acceptance Model (TAM). We surveyed 942 healthcare professionals over two weeks and performed a structural equation modeling (SEM) analysis to identify the intention to use the system among the participants. Next, we compared the results of the SEM analysis with the results of the analyses of the actual log files for two years to identify further insights into the factors that affected the intention of use. For these analyses, we used SAS 9.0 and AMOS 21. Of the 942 surveyed end-users, 48.3 % (23.2 % doctors and 68.3 % nurses) responded. After eliminating six subjects who completed the survey insincerely, we conducted the SEM analyses on the data from 449 subjects (65 doctors and 385 nurses). The newly suggested model satisfied the standards of model fitness, and the intention to use it was especially high due to the influences of Performance Expectancy on Attitude and Attitude. Based on the actual usage log analyses, both the doctors and nurses used the menus to view the inpatient lists, alerts, and patients' clinical data with high frequency. Specifically, the doctors frequently retrieved laboratory results, and the nurses frequently retrieved nursing notes and used the menu to assume the responsibilities of nursing work. In this

  19. Mobility Challenges

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lassen, Claus

    2011-01-01

    This article takes point of departure in the challenges to understand the importance of contemporary mobility. The approach advocated is a cross-disciplinary one drawing on sociology, geography, urban planning and design, and cultural studies. As such the perspective is to be seen as a part...... mobilities. In particular the article discusses 1) the physical city, its infrastructures and technological hardware/software, 2) policies and planning strategies for urban mobility and 3) the lived everyday life in the city and the region....... of the so-called ‘mobility turn’ within social science. The perspective is illustrative for the research efforts at the Centre for Mobility and Urban Studies (C-MUS), Aalborg University. The article presents the contours of a theoretical perspective meeting the challenges to research into contemporary urban...

  20. Intensive mobilities

    DEFF Research Database (Denmark)

    Vannini, Phillip; Bissell, David; Jensen, Ole B.

    which relate to transport, housing and employment. Yet we argue that the experiential dimensions of long distance mobilities have not received the attention that they deserve within geographical research on mobilities. This paper combines ideas from mobilities research and contemporary social theory......This paper explores the intensities of long distance commuting journeys as a way of exploring how bodily sensibilities are being changed by the mobilities that they undertake. The context of this paper is that many people are travelling further to work than ever before owing to a variety of factors...... with fieldwork conducted in Canada, Denmark and Australia to develop our understanding of the experiential politics of long distance workers. Rather than focusing on the extensive dimensions of mobilities that are implicated in patterns and trends, our paper turns to the intensive dimensions of this experience...

  1. Mobilities Design

    DEFF Research Database (Denmark)

    Jensen, Ole B.; Lanng, Ditte Bendix

    2016-01-01

    and physical form. The exchange value with design is twofold; first this means getting closer to the ‘material’ which is needed if mobilities research can claim to have understood contemporary mobilities, second it means that the creative, explorative and experimental approaches of the design world becomes...... insights, concepts of space and place, and relations between fixities and flows. The new and emerging field of ‘mobilities design’ will be exploring the borderlines between architecture, urban design, urban planning, and infrastructure design. The field will address the ‘gap’ in research on an issue...... of increasing concern and societal importance, regardless if the focus is on new inequalities, environmental sustainability, or the meaning of vernacular mobilities design to the everyday life. The theme of ‘mobilities design’ opens up the agenda of architectural research into infrastructure spaces as ‘spaces...

  2. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    networks, creating a vast fertile ground for novel developments in both research and practical applications Considers research directions, emerging trends and visions This book is an excellent resource for wireless/networking researchers in industry and academia, students and mobile phone programmers...... users in very different ways and for various purposes. The book provides many stimulating examples of resource-sharing applications. Enabling technologies for mobile clouds are also discussed, highlighting the key role of network coding. Mobile clouds have the potential to enhance communications...... examples of mobile clouds applications, based on both existing commercial initiatives as well as proof-of-concept test-beds. Visions and prospects are also discussed, paving the way for further development. As mobile networks and social networks become more and more reliant on each other, the concept...

  3. Patterns of acetaminophen medication use associated with exceeding the recommended maximum daily dose.

    Science.gov (United States)

    Shiffman, Saul; Rohay, Jeffrey M; Battista, Deena; Kelly, Judith P; Malone, Mary K; Weinstein, Rachel B; Kaufman, David W

    2015-09-01

    Acetaminophen overuse has been linked to liver injury. To identify patterns of medication use associated with exceeding the recommended daily maximum dose of 4 g acetaminophen. Respondents from a national panel completed a detailed daily medication diary online for 7 days (n = 5649), identifying medications taken from a comprehensive list of over-the-counter (OTC) and prescription (Rx) acetaminophen medications. Respondents were not told the study concerned acetaminophen. Total daily intake was calculated from diary data. Generalized estimating equations assessed the association of medication patterns with exceeding 4 g per day among 3618 respondents who used acetaminophen medications (on 13,852 days) during the diary period. Acetaminophen intake exceeded 4 g on 3.1% of usage days; median intake on those days was 5.5 g. As expected, days when intake exceeded 4 g were almost always (92%) marked by deviations from label directions-exceeding the one-time dose, re-dosing too soon, and concomitant use of multiple acetaminophen medications. Re-dosing too soon was the most frequent deviation, and concomitant use was most strongly tied to exceeding the daily limit. Use of both an Rx and an OTC medication on the same day also increased the odds of exceeding 4 g on days when concomitant use occurred. Excess dosing of acetaminophen is associated with deviations from label directions and by use of both OTC and Rx medications containing acetaminophen within a single concomitant use day. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Physical understanding of electron mobility in asymmetrically strained InGaAs-on-insulator metal-oxide-semiconductor field-effect transistors fabricated by lateral strain relaxation

    Science.gov (United States)

    Kim, SangHyeon; Yokoyama, Masafumi; Ikku, Yuki; Nakane, Ryosho; Ichikawa, Osamu; Osada, Takenori; Hata, Masahiko; Takenaka, Mitsuru; Takagi, Shinichi

    2014-03-01

    In this paper, we fabricated asymmetrically tensile-strained In0.53Ga0.47As-on-insulator (-OI) metal-oxide-semiconductor field-effect transistors (MOSFETs) using a lateral strain relaxation technique. A stripe-like line structure, fabricated in biaxially strained In0.53Ga0.47As-OI can lead to the lateral strain relaxation and asymmetric strain configuration in In0.53Ga0.47As-OI with the channel width of 100 nm. We have found that the effective mobility (μeff) enhancement in In0.53Ga0.47As-OI MOSFETs with uniaxial-like asymmetric strain becomes smaller than that in In0.53Ga0.47As-OI MOSFETs with biaxial strain. We have clarified from a systematic analysis between the strain values and the μeff characteristics that this mobility behavior can be understood by the change of the energy level of the conduction band minimum due to the lateral strain relaxation.

  5. Graphene mobility mapping

    DEFF Research Database (Denmark)

    Buron, Jonas Christian Due; Pizzocchero, Filippo; Jepsen, Peter Uhd

    2015-01-01

    Carrier mobility and chemical doping level are essential figures of merit for graphene, and large-scale characterization of these properties and their uniformity is a prerequisite for commercialization of graphene for electronics and electrodes. However, existing mapping techniques cannot directly...... assess these vital parameters in a non-destructive way. By deconvoluting carrier mobility and density from non-contact terahertz spectroscopic measurements of conductance in graphene samples with terahertz-transparent backgates, we are able to present maps of the spatial variation of both quantities over...... graphene indicates dominance by charged scatterers. Unexpectedly, significant variations in mobility rather than doping are the cause of large conductance inhomogeneities, highlighting the importance of statistical approaches when assessing large-area graphene transport properties....

  6. Enhancement of hole mobility in InSe monolayer via an InSe and black phosphorus heterostructure.

    Science.gov (United States)

    Ding, Yi-Min; Shi, Jun-Jie; Xia, Congxin; Zhang, Min; Du, Juan; Huang, Pu; Wu, Meng; Wang, Hui; Cen, Yu-Lang; Pan, Shu-Hang

    2017-10-05

    To enhance the low hole mobility (∼40 cm 2 V -1 s -1 ) of InSe monolayer, a novel two-dimensional (2D) van der Waals heterostructure made of InSe and black phosphorus (BP) monolayers with high hole mobility (∼10 3 cm 2 V -1 s -1 ) has been constructed and its structural and electronic properties are investigated using first-principles calculations. We find that the InSe/BP heterostructure exhibits a direct band gap of 1.39 eV and type-II band alignment with electrons (holes) located in the InSe (BP) layer. The band offsets of InSe and BP are 0.78 eV for the conduction band minimum and 0.86 eV for the valence band maximum, respectively. Surprisingly, the hole mobility in the InSe/BP heterostructure exceeds 10 4 cm 2 V -1 s -1 , which is one order of magnitude larger than the hole mobility of BP and three orders larger than that of the InSe monolayer. The electron mobility is also increased to 3 × 10 3 cm 2 V -1 s -1 . The physical reason has been analyzed deeply, and a universal method is proposed to improve the carrier mobility of 2D materials by forming heterostructures with them and other 2D materials with complementary properties. The InSe/BP heterostructure can thus be widely used in nanoscale InSe-based field-effect transistors, photodetectors and photovoltaic devices due to its type-II band alignment and high carrier mobility.

  7. Electronic Services Monthly MI Report

    Data.gov (United States)

    Social Security Administration — This electronic services monthly MI report contains monthly MI data for most public facing online online applications such as iClaim, electronic access, Mobile wage...

  8. The Use of the Academic Electronic Medical Record (EMR) to Develop Critical Thinking Skills in an Associate Degree Nursing Mobility Program

    Science.gov (United States)

    Wlodyga, Linda J.

    2010-01-01

    In an attempt to prepare new graduate nurses to meet the demands of health care delivery systems, the use of computer-based clinical information systems that combine hands-on experience with computer based information systems was explored. Since the introduction of Electronic Medical Records (EMR) nearly two decades ago, the demand for nurses to…

  9. Breakdown voltage enhancement of AlGaN/GaN high electron mobility transistors by polyimide/chromium composite thin film passivation

    Science.gov (United States)

    Futong, Chu; Chao, Chen; Xingzhao, Liu

    2014-03-01

    A novel AlGaN/GaN high electric mobility transistor (HEMT) with polyimide (PI)/chromium (Cr) as the passivation layer is proposed for enhancing breakdown voltage and its DC performance is also investigated. The Cr nanoparticles firstly introduced in PI thin films by the co-evaporation can be used to increase the permittivity of PI film. The high-permittivity PI/Cr passivation acting as field plate can suppress the fringing electric field peak at the drain-side edge of the gate electrode. This mechanism is demonstrated in accord with measured results. The experimental results show that in comparison with the AlGaN/GaN HEMTs without passivation, the breakdown voltage of HEMTs with the PI/Cr composite thin films can be significantly improved, from 122 to 248 V.

  10. Biaxially strained extremely-thin body In0.53Ga0.47As-on-insulator metal-oxide-semiconductor field-effect transistors on Si substrate and physical understanding on their electron mobility

    Science.gov (United States)

    Kim, SangHyeon; Yokoyama, Masafumi; Nakane, Ryosho; Ichikawa, Osamu; Osada, Takenori; Hata, Masahiko; Takenaka, Mitsuru; Takagi, Shinichi

    2013-10-01

    We report the electrical characteristics of strained In0.53Ga0.47As-on-insulator (-OI) metal-oxide-semiconductor field-effect-transistors (MOSFETs) on Si substrates fabricated by a direct wafer bonding (DWB) technique. 1.7% highly strained In0.53Ga0.47As-OI structures are fabricated on Si substrate by DWB. Strained In0.53Ga0.47As-OI MOSFETs with Ni-InGaAs metal source/drain (S/D) have been operated with high on-current (Ion)/off-current (Ioff) ratio of ˜105 and good current saturation in output characteristics. MOSFETs with 1.7% tensile strain exhibits 1.65 × effective mobility (μeff) enhancement against In0.53Ga0.47As MOSFET without strain. We found that this μeff enhancement is attributed to the increase in mobile free electron concentration under tensile strain, which leads to the lowering in the conduction band minimum (CBM) and the increase in the energy difference between CBM and the Fermi level pinning position due to a large amount of interface states by Hall measurements.

  11. Maps of critical loads and exceedance for sulfur and nitrogen to forest soils in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Frogner, T.; Wright, R.F.; Cosby, B.J.; Esser, J.M.

    1994-12-31

    This report uses the dynamic MAGIC (Model of Acidification of Groundwater in Catchments) model to calculate critical loads of sulfur and nitrogen for forest soils in Norway. Inputs include soil survey data, atmospheric deposition data, forest productivity data, and surface water chemistry. Two scenarios for future sulfur deposition are used with two scenarios of nitrogen retention in catchments. The magnitude and patterns of calculated nitrogen critical loads and exceedance differ substantially depending on the scenario chosen for sulfur deposition and nitrogen retention. In the worst case, critical loads for N are low and exceeded in southernmost Norway. In the best case, critical loads for N are high and not exceeded. More information on the processes controlling N retention in forested ecosystems is of utmost importance for the specification of nitrogen critical loads. 25 refs., 14 figs., 1 table

  12. A two-dimensional fully analytical model with polarization effect for off-state channel potential and electric field distributions of GaN-based field-plated high electron mobility transistor

    Science.gov (United States)

    Mao, Wei; She, Wei-Bo; Yang, Cui; Zhang, Chao; Zhang, Jin-Cheng; Ma, Xiao-Hua; Zhang, Jin-Feng; Liu, Hong-Xia; Yang, Lin-An; Zhang, Kai; Zhao, Sheng-Lei; Chen, Yong-He; Zheng, Xue-Feng; Hao, Yue

    2014-08-01

    In this paper, we present a two-dimensional (2D) fully analytical model with consideration of polarization effect for the channel potential and electric field distributions of the gate field-plated high electron mobility transistor (FP-HEMT) on the basis of 2D Poisson's solution. The dependences of the channel potential and electric field distributions on drain bias, polarization charge density, FP structure parameters, AlGaN/GaN material parameters, etc. are investigated. A simple and convenient approach to designing high breakdown voltage FP-HEMTs is also proposed. The validity of this model is demonstrated by comparison with the numerical simulations with Silvaco—Atlas. The method in this paper can be extended to the development of other analytical models for different device structures, such as MIS-HEMTs, multiple-FP HETMs, slant-FP HEMTs, etc.

  13. Factors involved in the electronic mobility within the chelate ring of the linkage isomers of Co(II), Ni(II) and Cu(II) complexes with vicinal oxime-imine ligands; An IR study

    Science.gov (United States)

    Aly, Mohamed M.; Stephanos, Joseph J.

    The electron mobility in the five- and six-membered chelate rings of the LM complexes [H 2L = N, N'-ethylenebis(isonitrosoacetylacetoneimine); M = divalent Ni, Co or Cu ions] is discussed in relation to the stability of the chelate isomers. The vibrational energies of the NO, CN and CO binding are related to the second or third ionization potential of the metal ions. This relationship is used for the calculation of ν (NO), ν (CN) and ν (CO) of a metal complex from the data of a prepared metal complex. The role of non-coordinated carbonyl group is discussed in relation to the imine nephelauxetic power which accounts for: (a) the conversion of the chelate isomer; and (b) the surprising stability of both modes of coordination by the oximato group in bis(4-iminopentane-2,3-dione 3-oximato) nickel(II).

  14. Sustainable Mobility

    DEFF Research Database (Denmark)

    Kjærulff, Aslak Aamot

    This paper combines strands of mobilities theory and planning theory, and develops a qualitative approach to look across emerging planning practices. By actively following 8 Danish urban and transport planners, over the course of 2 years, we learn how their practices have changed, inspired...... by mobility management, a concept aiming to reduce carbon emissions from transportation in western societies. The article focuses on how municipal planners formulate the role of mobility management activities organized around private companies, and how their practices are connected to wider ideas on planning....

  15. Going Mobile?

    DEFF Research Database (Denmark)

    Tallon, Loic; Froes, Isabel Cristina G.

    2011-01-01

    If the future is mobile, how is the museum community developing within that future? What are the challenges museums face within it? In which directions should we be seeking to evolve our collective knowledge share? It was to gain observations on questions such as these that the 2011 Museums...... & Mobile survey was developed: 660 museum professionals responded. In this paper the authors highlight nine survey observations that they believe are important to the museum community’s increased understanding of and continued progress within mobile interpretation....

  16. Toward Environmentally Robust Organic Electronics: Approaches and Applications.

    Science.gov (United States)

    Lee, Eun Kwang; Lee, Moo Yeol; Park, Cheol Hee; Lee, Hae Rang; Oh, Joon Hak

    2017-11-01

    Recent interest in flexible electronics has led to a paradigm shift in consumer electronics, and the emergent development of stretchable and wearable electronics is opening a new spectrum of ubiquitous applications for electronics. Organic electronic materials, such as π-conjugated small molecules and polymers, are highly suitable for use in low-cost wearable electronic devices, and their charge-carrier mobilities have now exceeded that of amorphous silicon. However, their commercialization is minimal, mainly because of weaknesses in terms of operational stability, long-term stability under ambient conditions, and chemical stability related to fabrication processes. Recently, however, many attempts have been made to overcome such instabilities of organic electronic materials. Here, an overview is provided of the strategies developed for environmentally robust organic electronics to overcome the detrimental effects of various critical factors such as oxygen, water, chemicals, heat, and light. Additionally, molecular design approaches to π-conjugated small molecules and polymers that are highly stable under ambient and harsh conditions are explored; such materials will circumvent the need for encapsulation and provide a greater degree of freedom using simple solution-based device-fabrication techniques. Applications that are made possible through these strategies are highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Miniaturized Ion Mobility Spectrometer

    Science.gov (United States)

    Kaye, William J (Inventor); Stimac, Robert M. (Inventor)

    2017-01-01

    By utilizing the combination of a unique electronic ion injection control circuit in conjunction with a particularly designed drift cell construction, the instantly disclosed ion mobility spectrometer (IMS) achieves increased levels of sensitivity, while achieving significant reductions in size and weight. The instant IMS is of a much simpler and easy to manufacture design, rugged and hermetically sealed, capable of operation at high temperatures to at least 250 degrees Centigrade, and is uniquely sensitive, particularly to explosive chemicals.

  18. 49 CFR 24.502 - Replacement housing payment for 180-day mobile homeowner displaced from a mobile home, and/or...

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Replacement housing payment for 180-day mobile... ACQUISITION FOR FEDERAL AND FEDERALLY-ASSISTED PROGRAMS Mobile Homes § 24.502 Replacement housing payment for... payment, not to exceed $22,500, under § 24.401 if: (1) The person occupied the mobile home on the...

  19. Achievement of normally-off AlGaN/GaN high-electron mobility transistor with p-NiO{sub x} capping layer by sputtering and post-annealing

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Shyh-Jer [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan (China); Chou, Cheng-Wei, E-mail: j2222222229@gmail.com [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan (China); Su, Yan-Kuin, E-mail: yksu@mail.ncku.edu.tw [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan (China); Lin, Jyun-Hao; Yu, Hsin-Chieh; Chen, De-Long [Department of Electrical Engineering, Institute of Microelectronics and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan (China); Ruan, Jian-Long [National Chung-Shan Institute of Science and Technology, Taoyuan, Taiwan (China)

    2017-04-15

    Highlights: • A technique to fabricate normally off GaN-based high-electron mobility transistor (HEMT) by sputtering and post-annealing p-NiO{sub x} capping layer. • The V{sub th} shifts from −3 V in the conventional transistor to 0.33 V, and on/off current ratio became 10{sup 7}. • The reverse gate leakage current is 10{sup −9} A/mm, and the off-state drain-leakage current is 10{sup −8} A/mm. • The V{sub th} hysteresis is extremely small at about 33 mV. - Abstract: In this paper, we present a technique to fabricate normally off GaN-based high-electron mobility transistor (HEMT) by sputtering and post-annealing p-NiO{sub x} capping layer. The p-NiO{sub x} layer is produced by sputtering at room temperature and post-annealing at 500 °C for 30 min in pure O{sub 2} environment to achieve high hole concentration. The V{sub th} shifts from −3 V in the conventional transistor to 0.33 V, and on/off current ratio became 10{sup 7}. The forward and reverse gate breakdown increase from 3.5 V and −78 V to 10 V and −198 V, respectively. The reverse gate leakage current is 10{sup −9} A/mm, and the off-state drain-leakage current is 10{sup −8} A/mm. The V{sub th} hysteresis is extremely small at about 33 mV. We also investigate the mechanism that increases hole concentration of p-NiO{sub x} after annealing in oxygen environment resulted from the change of Ni{sup 2+} to Ni{sup 3+} and the surge of (111)-orientation.

  20. Globalization and International Student Mobility: A Network Analysis

    Science.gov (United States)

    Shields, Robin

    2013-01-01

    This article analyzes changes to the network of international student mobility in higher education over a 10-year period (1999-2008). International student flows have increased rapidly, exceeding 3 million in 2009, and extensive data on mobility provide unique insight into global educational processes. The analysis is informed by three theoretical…

  1. Restricted Mobilities

    DEFF Research Database (Denmark)

    Nielsen, Mette; Lassen, Claus

    2012-01-01

    communities and shopping centres through mobility lenses. The article shows how different mobility systems enable and restrict the public access to private-public spaces, and it points out that proprietary communities create an unequal potential for human movement and access in the city. The main argument......Privatisation of public spaces in the contemporary city has increased during the last decades but only few studies have approached this field from a mobility perspective. Therefore the article seeks to rectify this by exploring two Australian examples of private spaces in the city; gated...... in the article is that the many mobility systems enable specialization of places that are targeted at a special section of the population. This means that various forms of motilities not only create new opportunities for urban life but it is also one of the most critical components of production of new exclusion...

  2. Staying Mobile

    Science.gov (United States)

    ... favorite. People who use scooters and wheelchairs bowl, fish, ski, and play golf, tennis or basketball. Enable ... the Independent Care System of NY addresses the importance of selecting the wheeled mobility device that best ...

  3. Mobile museology

    DEFF Research Database (Denmark)

    Baggesen, Rikke Haller

    Drawing together perspectives from museology, digital culture studies and fashion theory, this thesis considers changes in and challenges for current - day museums as related to ‘mobile museology’. This concept is developed for and elucidated in the thesis to describe an orientation towards...... the fashionable, the ephemeral, and towards an (ideal) state of change and changeability. This orientation is characterised with the triplet concepts of mobile, mobility, and mobilisation, as related to mobile media and movability; to ‘trans - museal’ mediation; and to the mobilisation of collections, audiences...... and institutional mindsets. The research project’s transdisciplinary and exploratory approach takes inspiration from critical design, minding Latour’s (2004a) call for rethink ing critical approaches in the humanities. Through a creative process, focused on designs for framing fashion in everyday contexts...

  4. An open-access mobile compatible electronic patient register for rheumatic heart disease (?eRegister?) based on the World Heart Federation?s framework for patient registers

    OpenAIRE

    van Dam, Joris; Tadmor, Brigitta; Spector, Jonathan; Musuku, John; Z?hlke, Liesl J; Engel, Mark E; Mayosi, Bongani M.; Nestle, Nick

    2015-01-01

    Summary Background Rheumatic heart disease (RHD) remains a major disease burden in low-resource settings globally. Patient registers have long been recognised to be an essential instrument in RHD control and elimination programmes, yet to date rely heavily on paper-based data collection and non-networked data-management systems, which limit their functionality. Objectives To assess the feasibility and potential benefits of producing an electronic RHD patient register. Methods We developed an ...

  5. Mobile Commerce

    Directory of Open Access Journals (Sweden)

    Maria Cristina Enache

    2016-07-01

    Full Text Available Mobile commerce, or m-commerce, refers to the use of wireless digital devices to enable transactions on the Web. Described more fully in Chapter 3, m-commerce involves the use of wireless networks to connect cell phones, handheld devices such Blackberries, and personal computers to the Web. Once connected, mobile consumers can conduct transactions, including stock trades, in-store price comparisons, banking, travel reservations, and more.

  6. The Probability of Exceedance as a Nonparametric Person-Fit Statistic for Tests of Moderate Length

    NARCIS (Netherlands)

    Tendeiro, Jorge N.; Meijer, Rob R.

    2013-01-01

    To classify an item score pattern as not fitting a nonparametric item response theory (NIRT) model, the probability of exceedance (PE) of an observed response vector x can be determined as the sum of the probabilities of all response vectors that are, at most, as likely as x, conditional on the

  7. Importance of the pre-industrial baseline for likelihood of exceeding Paris goals

    Science.gov (United States)

    Schurer, Andrew P.; Mann, Michael E.; Hawkins, Ed; Tett, Simon F. B.; Hegerl, Gabriele C.

    2017-08-01

    During the Paris conference in 2015, nations of the world strengthened the United Nations Framework Convention on Climate Change by agreeing to holding `the increase in the global average temperature to well below 2 °C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5 °C' (ref. ). However, `pre-industrial' was not defined. Here we investigate the implications of different choices of the pre-industrial baseline on the likelihood of exceeding these two temperature thresholds. We find that for the strongest mitigation scenario RCP2.6 and a medium scenario RCP4.5, the probability of exceeding the thresholds and timing of exceedance is highly dependent on the pre-industrial baseline; for example, the probability of crossing 1.5 °C by the end of the century under RCP2.6 varies from 61% to 88% depending on how the baseline is defined. In contrast, in the scenario with no mitigation, RCP8.5, both thresholds will almost certainly be exceeded by the middle of the century with the definition of the pre-industrial baseline of less importance. Allowable carbon emissions for threshold stabilization are similarly highly dependent on the pre-industrial baseline. For stabilization at 2 °C, allowable emissions decrease by as much as 40% when earlier than nineteenth-century climates are considered as a baseline.

  8. Exceedingly facile one-pot protocols to the synthesis of pyrimido ...

    African Journals Online (AJOL)

    Exceedingly facile one-pot protocols to the synthesis of pyrimido annulated analogues of carbazolo condensed azepinones and their evaluation for analgesic activity. ... writhing model in mice. Among them, compound 13was found to be most active and found comparable to standard aspirin. KEY WORDS: 3-Amino-9-ethyl ...

  9. The (mis)fortunes of exceeding a small local air market: comparing Amsterdam and Brussels

    NARCIS (Netherlands)

    Burghouwt, G.; Dobruszkes, F.

    2014-01-01

    Comparing air service growth in Amsterdam and Brussels, this paper aims to understand how the strategies of airlines and public authorities allow certain medium-sized cities to succeed in exceeding their local market by connecting passengers, while others do not. In contrast to Brussels, Amsterdam

  10. What could have caused pre-industrial biomass burning emissions to exceed current rates?

    NARCIS (Netherlands)

    Werf, van der G.R.; Peters, W.; Leeuwen, van T.T.; Giglio, L.

    2013-01-01

    Recent studies based on trace gas mixing ratios in ice cores and charcoal data indicate that biomass burning emissions over the past millennium exceeded contemporary emissions by up to a factor of 4 for certain time periods. This is surprising because various sources of biomass burning are linked

  11. What could have caused pre-industrial biomass burning emissions to exceed current rates?

    NARCIS (Netherlands)

    van der Werf, G. R.; Peters, W.; van Leeuwen, T. T.; Giglio, L.

    2012-01-01

    Recent studies based on trace gas mixing ratios in ice cores and charcoal data indicate that biomass burning emissions over the past millennium exceeded contemporary emissions by up to a factor of 4 for certain time periods. This is surprising because various sources of biomass burning are linked

  12. Restructuring to Promote Collaboration and Exceed User Needs: The Blackwell Library Access Services Experience

    Science.gov (United States)

    Chakraborty, Mou; English, Michael; Payne, Sharon

    2013-01-01

    Through vision, leadership, and creativity, Salisbury University's Blackwell Library transformed its access services department structurally and philosophically to better position itself to meet, and strive to exceed, today's user needs and expectations. Restructuring and the introduction of new leadership and new ideas provided the foundation for…

  13. Using Exceedance Probability to Determine Total Maximum Daily Loads for Reservoir Water Quality Management

    Directory of Open Access Journals (Sweden)

    Chi-Feng Chen

    2016-11-01

    Full Text Available Total maximum daily loads (TMDLs are used to protect water bodies based on their assimilative ability and are transferred as a maximum allowable load, which is the sum of all pollution emissions in a watershed that cannot be exceeded. This allowable load is calculated from a target water quality concentration and a flow state. The target water quality concentration is typically consistent with water quality standards; however, it is difficult to determine which flow state to use, especially for lakes and reservoirs. In this study, an exceedance probability method is established for determining the TMDL for reservoirs. The SWMM (Storm Water Management Model was used to understand the pollution loads from the watershed, and the Vollenweider model was used to simulate the total phosphorous (TP concentrations in the reservoir. Using the validated Vollenweider model, the relationship between pollution loads and the target TP concentration is illustrated. This relationship is associated with real changes in the reservoir water volume and is presented as the exceedance probability. In the study area (i.e., the Shiman Reservoir in Taiwan, an exceedance probability of 50% is suggested, and the allowable TP load is 22,209 kg/year when considering a target TP concentration of 20 μg/L. When considering effective management, the pollution sources in three hot spots are priorities, and controlling their point and nonpoint pollution sources can decrease TP from 25 to 22 μg/L.

  14. Comparison of two data assimilation methods for assessing PM10 exceedances on the European scale

    NARCIS (Netherlands)

    Denby, B.; Schaap, M.; Segers, A.; Builtjes, P.; Horálek, J.

    2008-01-01

    Two different data assimilation techniques have been applied to assess exceedances of the daily and annual mean limit values for PM10 on the regional scale in Europe. The two methods include a statistical interpolation method (SI), based on residual kriging after linear regression of the model, and

  15. Comparison of two data assimilation methods for assessing PM 10 exceedances on the European scale

    NARCIS (Netherlands)

    Denby, B.; Schaap, M.; Segers, A.J.; Builtjes, P.J.H.; Horalek, J.

    2008-01-01

    Two different data assimilation techniques have been applied to assess exceedances of the daily and annual mean limit values for PM10 on the regional scale in Europe. The two methods include a statistical interpolation method (SI), based on residual kriging after linear regression of the model, and

  16. Mobile Platform Development for SSC Propulsion Test Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A review of mobile applications (apps) and portable electronic tools/mobile platforms (that could be used by propulsion testing field users at SSC) was conducted....

  17. Pollution Critical Load Exceedance and an Extended Growing Season as Modulators of Red Spruce Radial Growth

    Science.gov (United States)

    Kosiba, A. M.; Schaberg, P. G.; Engel, B. J.; Rayback, S. A.; Hawley, G. J.; Pontius, J.; Miller, E. K.

    2016-12-01

    Acidic sulfur (S) and nitrogen (N) deposition depletes cations such as calcium (Ca) from forest soils and has been linked to increases in foliar winter injury that led to the decline of red spruce (Picea rubens Sarg.) in the northeastern United States. We used results from a 30 m resolution steady-state S and N critical load exceedance model for New England to better understand the spatial connections between Ca depletion and red spruce productivity. To calculate exceedance, atmospheric deposition was estimated for a 5-year period (1984-1988) because tree health and productivity declines were expected to be most responsive to high acid loading. We examined how radial growth (basal area increment) of 441 dominant and co-dominant red spruce trees from 37 sites across Vermont and New Hampshire was related to modeled estimates of S and N critical load exceedance. We assessed growth using statistical models with exceedance as a source of variation, but which also included "year" and "elevation class" (to help account for climatic variability) and interactions among factors. Exceedance was significantly and negatively associated with mean growth for the study period (1951-2010) overall, and particularly for the 1980s and 2000s - periods of numerous and/or severe foliar winter injury events. However, climate-related sources of variation (year and elevation) accounted for most of the differences in growth over the chronology. Interestingly, recent growth for red spruce is now the highest recorded over our dendrochronological record for the species - suggesting that the factors shaping growth may be changing. Because red spruce is a temperate conifer that has the capacity to photosynthesize year-round, it is possible that warmer temperatures may be extending the functional growing season of the species thereby fostering increased growth. Data from elevational transects on Mount Mansfield (Vermont's tallest mountain) indicate that warmer spring, summer, fall and even winter

  18. Superballistic flow of viscous electron fluid through graphene constrictions

    Science.gov (United States)

    Krishna Kumar, R.; Bandurin, D. A.; Pellegrino, F. M. D.; Cao, Y.; Principi, A.; Guo, H.; Auton, G. H.; Ben Shalom, M.; Ponomarenko, L. A.; Falkovich, G.; Watanabe, K.; Taniguchi, T.; Grigorieva, I. V.; Levitov, L. S.; Polini, M.; Geim, A. K.

    2017-12-01

    Electron-electron (e-e) collisions can impact transport in a variety of surprising and sometimes counterintuitive ways. Despite strong interest, experiments on the subject proved challenging because of the simultaneous presence of different scattering mechanisms that suppress or obscure consequences of e-e scattering. Only recently, sufficiently clean electron systems with transport dominated by e-e collisions have become available, showing behaviour characteristic of highly viscous fluids. Here we study electron transport through graphene constrictions and show that their conductance below 150 K increases with increasing temperature, in stark contrast to the metallic character of doped graphene. Notably, the measured conductance exceeds the maximum conductance possible for free electrons. This anomalous behaviour is attributed to collective movement of interacting electrons, which `shields' individual carriers from momentum loss at sample boundaries. The measurements allow us to identify the conductance contribution arising due to electron viscosity and determine its temperature dependence. Besides fundamental interest, our work shows that viscous effects can facilitate high-mobility transport at elevated temperatures, a potentially useful behaviour for designing graphene-based devices.

  19. Silicon-Vacancy Spin Qubit in Diamond: A Quantum Memory Exceeding 10 ms with Single-Shot State Readout

    Science.gov (United States)

    Sukachev, D. D.; Sipahigil, A.; Nguyen, C. T.; Bhaskar, M. K.; Evans, R. E.; Jelezko, F.; Lukin, M. D.

    2017-12-01

    The negatively charged silicon-vacancy (SiV- ) color center in diamond has recently emerged as a promising system for quantum photonics. Its symmetry-protected optical transitions enable the creation of indistinguishable emitter arrays and deterministic coupling to nanophotonic devices. Despite this, the longest coherence time associated with its electronic spin achieved to date (˜250 ns ) has been limited by coupling to acoustic phonons. We demonstrate coherent control and suppression of phonon-induced dephasing of the SiV- electronic spin coherence by 5 orders of magnitude by operating at temperatures below 500 mK. By aligning the magnetic field along the SiV- symmetry axis, we demonstrate spin-conserving optical transitions and single-shot readout of the SiV- spin with 89% fidelity. Coherent control of the SiV- spin with microwave fields is used to demonstrate a spin coherence time T2 of 13 ms and a spin relaxation time T1 exceeding 1 s at 100 mK. These results establish the SiV- as a promising solid-state candidate for the realization of quantum networks.

  20. Mobile healthcare.

    Science.gov (United States)

    Morgan, Stephen A; Agee, Nancy Howell

    2012-01-01

    Mobile technology's presence in healthcare has exploded over the past five years. The increased use of mobile devices by all segments of the US population has driven healthcare systems, providers, and payers to accept this new form of communication and to develop strategies to implement and leverage the use of mobile healthcare (mHealth) within their organizations and practices. As healthcare systems move toward a more value-driven model of care, patient centeredness and engagement are the keys to success. Mobile healthcare will provide the medium to allow patients to participate more in their care. Financially, mHealth brings to providers the ability to improve efficiency and deliver savings to both them and the healthcare consumer. However, mHealth is not without challenges. Healthcare IT departments have been reluctant to embrace this shift in technology without fully addressing security and privacy concerns. Providers have been hesitant to adopt mHealth as a form of communication with patients because it breaks with traditional models. Our healthcare system has just started the journey toward the development of mHealth. We offer an overview of the mobile healthcare environment and our approach to solving the challenges it brings to healthcare organizations.

  1. The Effects of Trust Transference, Mobile Attributes and Enjoyment on Mobile Trust

    Directory of Open Access Journals (Sweden)

    Cristiane Junqueira Giovannini

    2015-01-01

    Full Text Available Trust is essential in building relationships. In mobile commerce, as in electronic commerce, trust is even more valuable given the absence of human contact and direct observation of the service provider. Despite the importance of trust for mobile commerce, there has been little academic effort to study the relationships between mobile devices unique components of interactivity and customer trust, or the relationship between offline, online and mobile trust. This study proposes a trust-mediated model for customer attitude and transaction intentions in mobile commerce contexts that incorporates trust transference and unique factors present in mobile commerce. Data were collected in an online survey and analyzed via structural equations modeling. Results suggest that trust transferred from online contexts and ease of use have significant effects on mobile trust formation, while also indicating that mobile trust influences consumers’ attitudes and intentions to purchase using mobile devices.

  2. Method for enhancing the resolving power of ion mobility separations over a limited mobility range

    Science.gov (United States)

    Shvartsburg, Alexandre A; Tang, Keqi; Smith, Richard D

    2014-09-23

    A method for raising the resolving power, specificity, and peak capacity of conventional ion mobility spectrometry is disclosed. Ions are separated in a dynamic electric field comprising an oscillatory field wave and opposing static field, or at least two counter propagating waves with different parameters (amplitude, profile, frequency, or speed). As the functional dependencies of mean drift velocity on the ion mobility in a wave and static field or in unequal waves differ, only single species is equilibrated while others drift in either direction and are mobility-separated. An ion mobility spectrum over a limited range is then acquired by measuring ion drift times through a fixed distance inside the gas-filled enclosure. The resolving power in the vicinity of equilibrium mobility substantially exceeds that for known traveling-wave or drift-tube IMS separations, with spectra over wider ranges obtainable by stitching multiple segments. The approach also enables low-cutoff, high-cutoff, and bandpass ion mobility filters.

  3. Observed ozone exceedances in Italy: statistical analysis and modelling in the period 2002-2015

    Science.gov (United States)

    Falasca, Serena; Curci, Gabriele; Candeloro, Luca; Conte, Annamaria; Ippoliti, Carla

    2017-04-01

    Local ambient air quality is strongly influenced by anthropogenic emissions and meteorological conditions. The year 2015 is considered by NASA scientists as one of the hottest at the global scale since 1880. Furthermore, in Europe it was the first summer after the introduction of Euro6 regulation, the latest emission standard for passenger vehicles. The goal of this study is twofold: (1) the investigation of the impact of the heat wave occurred in the summer of 2015 on ozone levels and (2) the exploration of the weight of temperature as driver of high-level ozone events with respect to other variables. We performed a quantitative examination of the ozone seasons (May-September) for the period 2002-2015 using ozone concentration and weather data from 24 stations across Italy. The number of exceedances of limit values set by the European directive was calculated for each year, and compared with the trend of ozone concentration and temperature. Furthermore, the data were grouped in clusters of consecutive days of ozone exceedances in order to characterize the duration and the intensity of high ozone events. Finally, we developed a multivariate logistic regression model to investigate the role of a set of independent variables (meteorological, and temporal variables, altitude, number of inhabitants, vehicle emission standard) on the probability of exceedances. Results show that 2015 is one of the hottest years after 2003. During the period 2002-2015, the average number of exceedances per station of the daily maximum 8-hour average is often higher than the limit established by the European directive (25 per year). The highest number of exceedances was 65 per station, reached in 2003. The Po Valley is confirmed as a hot spot for pollution, with more frequent exceedances and a higher sensitivity to temperature, especially at urban sites. Ozone events in 2015 were fewer than recent years, but of longer duration (on average 4 days against 3 days), and with similar mean

  4. Mobile Phones for Teaching and Learning: Implementation and Students' and Teachers' Attitudes

    Science.gov (United States)

    AlTameemy, Farooq

    2017-01-01

    Mobile phones have become so ubiquitous that they turned into an important part of our life. According to Parsons, mobile subscriptions exceed 6 billion subscriptions globally. Similarly, Ipsos and Verizon (as cited in Tan & El-Bendary) found out that adopting mobile phones with smart technologies has increased fast which also coincided with a…

  5. 41 CFR 102-73.40 - What happens if the dollar value of the project exceeds the prospectus threshold?

    Science.gov (United States)

    2010-07-01

    ... dollar value of the project exceeds the prospectus threshold? 102-73.40 Section 102-73.40 Public... § 102-73.40 What happens if the dollar value of the project exceeds the prospectus threshold? Projects require approval by the Senate and the House of Representatives if the dollar value of a project exceeds...

  6. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    are often still not engaged with in a sufficiently manner. Often social sciences keep distance to the physical and material as if the social was still to be understood as a realm separate of technology, architecture, and design (for a critique of this see; Latour 2005 and Urry 2000). This paper takes point...... of departure in the sociological perspective termed ‘Staging Mobilities’ (Jensen 2013a) and utilizes this as an analytical frame for exploring cases of mobility design. The paper put focus on how the material shape, design and architectures of technologies, spaces and sites influence mobilities practices......, mobilitiy technologies or urban sites of movement we get much closer to understanding the meaning of mobilities to social interaction and culture. The cases are still representing work-in-progress but will be reported in the book ‘Designing Mobilites’ (Jensen 2013b) and will cover the four cases of...

  7. On the Accurate Modeling of Millimeter Wave Fixed Wireless Channels Exceedance Probability

    Science.gov (United States)

    Georgiadou, E. M.; Panagopoulos, A. D.; Chatzarakis, G. E.; Kanellopoulos, J. D.

    2006-07-01

    The ever increasing demand for high date rate multimedia services has led to the deployment of Fixed Wireless Access (FWA) networks operating in frequencies above 10GHz. Propagation characteristics of such networks include line-of-sight (LOS) transmissions highly influenced by the presence of rain. In this paper a methodology for evaluating the outage probability of a FWA channel is introduced, making use of the forward scattering amplitude by distorted raindrops of transmitted signals. Expressions for the imaginary part of the scattering amplitude are derived through a regression fitting analysis on the results of the Method of Auxiliary Sources (MAS) to the problem of electromagnetic scattering from a Pruppacher-Pitter raindrop. These expressions are employed and an analytical method to evaluate the rain attenuation exceedance probability over a fixed wireless access link is presented. The derived exceedance probabilities are compared with experimental data from ITU-R databank with encouraging results.

  8. Congenital syphilis after treatment of maternal syphilis with a penicillin regimen exceeding CDC guidelines.

    OpenAIRE

    Conover, C S; Rend, C A; Miller, G B; Schmid, G P

    1998-01-01

    BACKGROUND: Although congenital syphilis usually occurs as a result of a failure to detect and treat syphilis in pregnant women, failures of the currently recommended regimen to prevent congenital syphilis have been reported. CASE: This report describes an infant with congenital syphilis despite maternal treatment with a regimen exceeding current CDC guidelines. CONCLUSION: Regardless of the regimen used to treat syphilis during pregnancy, clinicians should recognize the possibility of occasi...

  9. Congenital Syphilis After Treatment of Maternal Syphilis With a Penicillin Regimen Exceeding CDC Guidelines

    OpenAIRE

    Craig S. Conover; Rend, Charles A.; Grayson B. Miller; Schmid, George P

    1998-01-01

    Background: Although congenital syphilis usually occurs as a result of a failure to detect and treat syphilis in pregnant women, failures of the currently recommended regimen to prevent congenital syphilis have been reported.Case: This report describes an infant with congenital syphilis despite maternal treatment with a regimen exceeding current CDC guidelines .Conclusion: Regardless of the regimen used to treat syphilis during pregnancy, clinicians should recognize the possibility of occasio...

  10. Mapping of Critical Loads and Critical Load Exceedances in the Killarney Provincial Park, Ontario, Canada

    OpenAIRE

    Hindar, A.; Henriksen, A.

    1998-01-01

    Calculations of critical loads for inputs of strong acids to lakes and exceedances of critical load can be a useful tool for the management of polluted areas. In Sudbury, Canada, large emissions of sulfur dioxide have resulted in widespread lake acidification in parts of northeastern Canada. Due to its vicinity to Sudbury, extensive lake acidification and fish loss has occurred in the Killarney Provincial Park. We have linked measured water quality to critical loads and strong acid deposition...

  11. Exceedance of critical loads and of critical limits impacts tree nutrition across Europe

    DEFF Research Database (Denmark)

    Waldner, P.; Thimonier, A.; Graf Pannatier, E.

    2015-01-01

    are not expected to occur. Aims We explored the relationship between the exceedance of critical loads and inorganic nitrogen concentration, the base cation to aluminium ratio in soil solutions, as well as the nutritional status of trees. Methods We used recent data describing deposition, elemental concentrations....... Conclusion The findings support the hypothesis that elevated nitrogen and sulphur deposition can lead to imbalances in tree nutrition....

  12. Derivation and Mapping of Critical Loads for Nitrogen and Trends in Their Exceedance in Germany

    Directory of Open Access Journals (Sweden)

    Hans-Dieter Nagel

    2001-01-01

    Full Text Available The term “critical load” means a quantitative estimate of an exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment do not occur, according to present knowledge. In the case of nitrogen, both oxidised and reduced compounds contribute to the total deposition of acidity, which exceeds critical loads in many forest ecosystems. These also cause negative effects through eutrophication. Critical loads of nitrogen were derived for forest soils (deciduous and coniferous forest, natural grassland, acid fens, heathland, and mesotrophic peat bogs. In Germany, a decrease in sulphur emissions over the past 15 years resulted in a reduced exceedance of critical loads for acid deposition. In the same period it was noted that reduction in the emissions of nitrogen oxides and ammonia remained insignificant. Therefore, emissions of nitrogen compounds have become relatively more important and will continue to threaten ecosystem function and stability. The risk of environmental damage remains at an unacceptable level. The German maps show the degree to which the critical loads are exceeded, and they present current developments and an expected future trend. Results indicate that recovery from pollutant stress occurs only gradually.

  13. Sound levels in a neonatal intensive care unit significantly exceeded recommendations, especially inside incubators.

    Science.gov (United States)

    Parra, Johanna; de Suremain, Aurelie; Berne Audeoud, Frederique; Ego, Anne; Debillon, Thierry

    2017-12-01

    This study measured sound levels in a 2008 built French neonatal intensive care unit (NICU) and compared them to the 2007 American Academy of Pediatrics (AAP) recommendations. The ultimate aim was to identify factors that could influence noise levels. The study measured sound in 17 single or double rooms in the NICU. Two dosimeters were installed in each room, one inside and one outside the incubators, and these conducted measurements over a 24-hour period. The noise metrics measured were the equivalent continuous sound level (Leq ), the maximum noise level (Lmax ) and the noise level exceeded for 10% of the measurement period (L10 ). The mean Leq , L10 and Lmax were 60.4, 62.1 and 89.1 decibels (dBA), which exceeded the recommended levels of 45, 50 and 65 dBA (p < 0.001), respectively. The Leq inside the incubator was significantly higher than in the room (+8 dBA, p < 0.001). None of the newborns' characteristics, the environment or medical care was correlated to an increased noise level, except for a postconceptional age below 32 weeks. The sound levels significantly exceeded the AAP recommendations, particularly inside incubators. A multipronged strategy is required to improve the sound environment and protect the neonates' sensory development. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

  14. Nitrogen deposition and exceedance of critical loads for nutrient nitrogen in Irish grasslands.

    Science.gov (United States)

    Henry, Jason; Aherne, Julian

    2014-02-01

    High resolution nitrogen (N) deposition maps were developed to assess the exceedance of empirical critical loads of nutrient N for grasslands in Ireland. Nitrogen emissions have remained relatively constant during the past 20 yrs and are projected to remain constant under current legislation. Total N deposition (estimated as wet nitrate [NO3(-)] and ammonium [NH4(+)] plus dry NO× and NH3) ranged from 2 to 22 kg Nha(-1)yr(-1) (mean=12 kg Nha(-1)yr(-1)) to grasslands. Empirical critical loads for nutrient N were set at 15 kg Nha(-1)yr(-1) for both acid and calcareous grasslands; exceedance was observed for ~35% (~2,311 km(2)) of mapped acid grasslands. In contrast, only ~9% of calcareous grasslands (~35 km(2)) received N deposition in excess of the critical load. Reduced N deposition (primarily dry NH3) represented the dominant form to grasslands (range 55-90%) owing to significant emissions associated with livestock (primarily cattle). The extent of exceedance in acid grasslands suggests that N deposition to this habitat type may lead to adverse impacts such as a decline in plant species diversity and soil acidification. Further, given that elevated N deposition was dominated by NH3 associated with agricultural emissions rather than long-range transboundary sources, future improvements in air quality need to be driven by national policies. © 2013.

  15. Recessed-gate quasi-enhancement-mode AlGaN/GaN high electron mobility transistors with oxygen plasma treatment

    Science.gov (United States)

    He, Yun-Long; Wang, Chong; Mi, Min-Han; Zheng, Xue-Feng; Zhang, Meng; Zhao, Meng-Di; Zhang, Heng-Shuang; Chen, Li-Xiang; Zhang, Jin-Cheng; Ma, Xiao-Hua; Hao, Yue

    2016-11-01

    In this paper, the enhancement-mode AlGaN/GaN HEMT combined with the low damage recessed-gate etching and the optimized oxygen plasma treatment was fabricated. Scanning electron microscope/energy dispersive spectrometer (SEM/EDS) method and x-ray photoelectron spectroscopy (XPS) method were used to confirm the formation of oxides. Based on the experimental results, the obtained enhancement-mode HEMT exhibited a threshold voltage of 0.5 V, a high peak transconductance of 210 mS/mm, and a maximum drain current of 610 mA/mm at the gate bias of 4 V. Meanwhile, the on/off current ratio of enhancement-mode HEMT was as high as 108, drain induced barrier lowering (DIBL) was as low as 5 mV/V, and subthreshold swing (SS) of 80 mV/decade was obtained. Compared with the conventional HEMT, the Schottky reverse current of enhancement-mode HEMT was three orders of magnitude lower, and the off-state breakdown voltage of which was higher. In addition, a power gain cutoff frequency (f max) of the enhancement-mode HEMT was larger than that of the conventional one. Project supported by the National Natural Science Foundation of China (Grant Nos. 61574110, 61334002, and 61474091) and the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2015AA016801).

  16. Mobile probes

    DEFF Research Database (Denmark)

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...

  17. Designing Mobilities

    DEFF Research Database (Denmark)

    Jensen, Ole B.

    How is the width of the pavement shaping the urban experience? How is the material design of transport infrastructure and mobile technology affording social interaction in everyday life spaces? How do people inhabit these spaces with their bodies and in accordance to social and cultural norms...

  18. Mobile Misfortune

    DEFF Research Database (Denmark)

    Vigh, Henrik Erdman

    2015-01-01

    of the mobility it enables. This article, thus, looks at the motives and manners in which young men in Bissau become caught up in transnational flows of cocaine. It shows how motion is emotively anchored and affectively bound: tied to and directed toward a feeling of worth and realisation of being, and how...

  19. Mobile IP

    NARCIS (Netherlands)

    Heijenk, Geert; Sallent, S.; Pras, Aiko

    1999-01-01

    The Internet is growing exponentially, both in the amount of traffic carried, and in the amount of hosts connected. IP technology is becoming more and more important, in company networks (Intranets), and also in the core networks for the next generation mobile networks. Further, wireless access to

  20. Enabling Routes as Context in Mobile Services

    DEFF Research Database (Denmark)

    Brilingaite, Agne; Jensen, Christian Søndergaard; Zokaite, Nora

    2004-01-01

    With the continuing advances in wireless communications, geo-positioning, and portable electronics, an infrastructure is emerging that enables the delivery of on-line, location-enabled services to very large numbers of mobile users. A typical usage situation for mobile services is one characterized...

  1. Enabling Routes as Context in Mobile Services

    DEFF Research Database (Denmark)

    Brilingaite, Agne; Jensen, Christian Søndergaard; Zokaite, Nora

    With the continuing advances in wireless communications, geo-positioning, and portable electronics, an infrastructure is emerging that enables the delivery of on-line, location-enabled services to very large numbers of mobile users. A typical usage situation for mobile services is one characterized...

  2. THE RISE OF MOBILE BANKING

    Directory of Open Access Journals (Sweden)

    IMOLA DRIGĂ

    2015-12-01

    Full Text Available To meet customer’s expectations and needs, electronic banking services have allowed financial transactions to simplify and have increased their attractiveness. Over the past few year, in order to increase customer comfort and maintain profitability, banks around the world have adopted innovative banking technologies and modern e-banking services, such as internet and mobile banking. As a matter of fact, banking over mobile phones is the newest e-banking service with several benefits for both customers and banks. The paper aims to provide an overview of the latest electronic financial channel, underlining various aspects of mobile banking as it represents a key distribution channel for a growing number of customers.

  3. Mobile-to-mobile wireless channels

    CERN Document Server

    Zajic, Alenka

    2013-01-01

    Present-day mobile communications systems can be classified as fixed-to-mobile because they allow mobility on only one end (e.g. the mobile phone to a fixed mobile operator's cell tower). In answer to the consumer demand for better coverage and quality of service, emerging mobile-to-mobile (M-to-M) communications systems allow mobile users or vehicles to directly communicate with each other. This practical book provides a detailed introduction to state-of-the-art M-to-M wireless propagation. Moreover, the book offers professionals guidance for rapid implementation of these communications syste

  4. Mobile Customer Relationship Management and Mobile Security

    Science.gov (United States)

    Sanayei, Ali; Mirzaei, Abas

    The purpose of this study is twofold. First, in order to guarantee a coherent discussion about mobile customer relationship management (mCRM), this paper presents a conceptualization of mCRM delineating its unique characteristics because of Among the variety of mobile services, considerable attention has been devoted to mobile marketing and in particular to mobile customer relationship management services. Second, the authors discusses the security risks in mobile computing in different level(user, mobile device, wireless network,...) and finally we focus on enterprise mobile security and it's subgroups with a series of suggestion and solution for improve mobile computing security.

  5. Effect of the Apulia air quality plan on PM10 and benzo(apyrene exceedances

    Directory of Open Access Journals (Sweden)

    L. Trizio

    2016-03-01

    Full Text Available During the last years, several exceedances of PM10 and benzo(apyrene limit values exceedances were recorded in Taranto, a city in southern Italy included in so-called areas at high risk of environmental crisis because of the presence of a heavy industrial district including the largest steel factory in Europe. A study of these critical pollution events showed a close correlation with the wind coming from the industrial site to the adjacent urban area. During 2011, at monitoring sites closes to the industrial area, at least the 65% of PM10 exceedances were related to wind day conditions (characterized by at least 3 consecutive hours of wind coming from 270-360±2deg with an associated speed higher than 7 m/s. For this reason, in 2012 an integrated environmental permit and a regional air quality plan were enacted to reduce pollutant emissions from industrial plants. A study of PM10 levels registered during windy days was performed during critical episodes of pollution highlighting that the difference between windy days and no windy days’ concentrations reduces from 2012 to 2014 in industrial site. False negative events (verified ex-post by observed meteorological data not identified by the forecast model - did not show a significant influence on PM concentration: PM10 values were comparable and sometimes lower than windy days levels. It is reasonable that the new scenario with a relevant reduction emissions form Ilva plant reduced the pollutants contribution from industrial area, contributing to PM10 levels decrease, also in false negative events.

  6. Planktivory in the changing Lake Huron zooplankton community: Bythotrephes consumption exceeds that of Mysis and fish

    Science.gov (United States)

    Bunnell, D.B.; Hunter, R. Douglas; Warner, D.M.; Chriscinske, M.A.; Roseman, E.F.

    2011-01-01

    Oligotrophic lakes are generally dominated by calanoid copepods because of their competitive advantage over cladocerans at low prey densities. Planktivory also can alter zooplankton community structure. We sought to understand the role of planktivory in driving recent changes to the zooplankton community of Lake Huron, a large oligotrophic lake on the border of Canada and the United States. We tested the hypothesis that excessive predation by fish (rainbow smelt Osmerus mordax, bloater Coregonus hoyi) and invertebrates (Mysis relicta, Bythotrephes longimanus) had driven observed declines in cladoceran and cyclopoid copepod biomass between 2002 and 2007. We used a field sampling and bioenergetics modelling approach to generate estimates of daily consumption by planktivores at two 91-m depth sites in northern Lake Huron, U.S.A., for each month, May-October 2007. Daily consumption was compared to daily zooplankton production. Bythotrephes was the dominant planktivore and estimated to have eaten 78% of all zooplankton consumed. Bythotrephes consumption exceeded total zooplankton production between July and October. Mysis consumed 19% of all the zooplankton consumed and exceeded zooplankton production in October. Consumption by fish was relatively unimportant - eating only 3% of all zooplankton consumed. Because Bythotrephes was so important, we explored other consumption estimation methods that predict lower Bythotrephes consumption. Under this scenario, Mysis was the most important planktivore, and Bythotrephes consumption exceeded zooplankton production only in August. Our results provide no support for the hypothesis that excessive fish consumption directly contributed to the decline of cladocerans and cyclopoid copepods in Lake Huron. Rather, they highlight the importance of invertebrate planktivores in structuring zooplankton communities, especially for those foods webs that have both Bythotrephes and Mysis. Together, these species occupy the epi-, meta- and

  7. Response Load Extrapolation for Wind Turbines during Operation Based on Average Conditional Exceedance Rates

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Naess, Arvid; Saha, Nilanjan

    2011-01-01

    within a hierarchical model where the variables that influence the loading are divided into ergodic variables and time-invariant non-ergodic variables. The presented method for statistical response load extrapolation was compared with the existing methods based on peak extrapolation for the blade out-of-plane...... bending moment and the tower mudline bending moment of a pitch-controlled wind turbine. In general, the results show that the method based on average conditional exceedance rates predicts the extrapolated characteristic response loads at the individual mean wind speeds well and results in more consistent...

  8. Large deviation estimates for exceedance times of perpetuity sequences and their dual processes

    DEFF Research Database (Denmark)

    Buraczewski, Dariusz; Collamore, Jeffrey F.; Damek, Ewa

    2016-01-01

    this estimate, and related estimates, to more general processes, little work has been devoted to understanding the path behavior of these processes. In this paper, we derive sharp asymptotic estimates for the large exceedance times of $\\{ Y_n \\}$. Letting $T_u := (\\log\\, u)^{-1} \\inf\\{n: Y_n > u \\}$ denote...... the normalized first passage time, we study ${\\mathbb P} \\left\\{ T_u \\in G \\right\\}$ as $u \\to \\infty$ for sets $G \\subset [0,\\infty)$. We show, first, that the scaled sequence $\\{ T_u \\}$ converges in probability to a certain constant $\\rho > 0$. Moreover, if $G \\cap [0,\\rho] \

  9. Design and implementation of an electronic architecture for an agricultural mobile robot Projeto e implementação de uma arquitetura eletrônica para um robô agrícola móvel

    Directory of Open Access Journals (Sweden)

    Eduardo P. Godoy

    2010-11-01

    Full Text Available A current trend in the agricultural area is the development of mobile robots and autonomous vehicles for remote sensing. One of the major challenges in the design of these robots is the development of the electronic architecture for the integration and control of the devices. Recent applications of mobile robots have used distributed architectures based on communication networks. A technology that has been widely used as an embedded network is the CAN protocol. The implementation of the ISO11783 standard represents the standardization of the CAN for application in agricultural machinery. This work describes the design and implementation of an electronic architecture for a mobile agricultural robot. The discussions are focused on the developed architecture, the wireless communication system for teleoperation and the distributed control based on CAN protocol and ISO11783. The evaluation of the developed system was based on the analysis of performance parameters such as motor response and architectural time delay obtained with the robot operation. The results show that the developed architecture can be applied for teleoperation and distributed control of agricultural robots meeting the requirements for accurate robot movement and an acceptable response time for robot control commands and supervision.Uma tendência atual na área agrícola é o desenvolvimento de robôs móveis e veículos autônomos para sensoriamento remoto. Um dos grandes desafios no projeto desses robôs é o desenvolvimento da arquitetura eletrônica para integração e controle dos dispositivos. Em aplicações recentes desses robôs tem-se utilizado arquiteturas distribuídas baseadas em redes de comunicação. Uma tecnologia amplamente usada como rede embarcada é o protocolo CAN. A implementação da norma ISO11783 representa a padronização do protocolo CAN para aplicações agrícolas. Este artigo apresenta o projeto e a implementação de uma arquitetura eletr

  10. The African Mobile Story

    DEFF Research Database (Denmark)

    This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks......This book identifies the factors that has enabled the growth of mobile telephony in Africa. The book covers the regulatory factors, the development and usage of mobile application, mobile security and sustainable power source for mobile networks...

  11. Liquid crystalline perylene diimide outperforming nonliquid crystalline counterpart: higher power conversion efficiencies (PCEs) in bulk heterojunction (BHJ) cells and higher electron mobility in space charge limited current (SCLC) devices.

    Science.gov (United States)

    Zhang, Youdi; Wang, Helin; Xiao, Yi; Wang, Ligang; Shi, Dequan; Cheng, Chuanhui

    2013-11-13

    In this work, we propose the application of liquid crystalline acceptors as a potential means to improve the performances of bulk heterojunction (BHJ) organic solar cells. LC-1, a structurally-simple perylene diimide (PDI), has been adopted as a model for thorough investigation. It exhibits a broad temperature range of liquid crystalline (LC) phase from 41 °C to 158 °C, and its LC properties have been characterized by differental scanning calorimetry (DSC), polarization optical microscopy (POM), and X-ray diffraction (XRD). The BHJ devices, using P3HT:LC-1 (1:2) as an organic photovoltaic active layer undergoing thermal annealing at 120 °C, shows an optimized efficiency of 0.94 %. By contrast, the devices based on PDI-1, a nonliquid crystalline PDI counterpart, only obtain a much lower efficiency of 0.22%. Atomic force microscopy (AFM) images confirm that the active layers composed of P3HT:LC-1 have smooth and ordered morphology. In space charge limited current (SCLC) devices fabricated via a spin-coating technique, LC-1 shows the intrinsic electron mobility of 2.85 × 10(-4) cm(2)/(V s) (at 0.3 MV/cm) which is almost 5 times that of PDI-1 (5.83 × 10(-5) cm(2)/(V s)) under the same conditions for thermal annealing at 120 °C.

  12. Three-dimensional steady and transient fully coupled electro-thermal simulation of AlGaN/GaN high electron mobility transistors: Effects of lateral heat dissipation and thermal crosstalk between gate fingers

    Directory of Open Access Journals (Sweden)

    Ashu Wang

    2017-09-01

    Full Text Available In this paper, we develop three-dimensional fully coupled electro-thermal (ET simulation for AlGaN/GaN high electron mobility transistors (HEMTs, which is a relative complete and accurate simulation compared to the current existed simulations, capable of describing the lateral ET behavior of the device. As applications of this simulation, we investigate impact of the gate width (WG and number of the gate fingers (NG on the steady and transient ET behavior of the device. The steady results show that the lateral heat dissipation and thermal crosstalk between the gate fingers significantly affects the ET behavior for the device with narrow gate and multifinger, respectively. However, the transient results show that, within a time scale after the device switching on, the ET behavior is not influenced by WG and NG, i.e., the lateral heat dissipation and thermal crosstalk have no effects. This indicates that when the device operating in high frequency, increasing WG and NG to improve the power output is not restricted by the self-heating.

  13. Urban Mobility

    DEFF Research Database (Denmark)

    2017-01-01

    This anthology is the proceedings publication from the 2015 NAF Symposium in Malmö, Sweden. The aim of the 2015 NAF Symposium “Urban Mobility – Architectures, Geographies and Social Space” was to facilitate a cross-disciplinary discussion on urban mobility in which the juxtaposition of different...... discursive perceptions of the concept would foster greater insight into and understanding of both the challenges and potentials that it represents. It focused on some of the key themes currently facing cities and the urban: the transformation of the city and our built environment; migration; rural decline......; the interaction between city, architecture, and inhabitants; the role of architects and architecture in the creation of democratic and sustainable urban contexts; the city and its representation; the politics of intervention; and the actions of governing and developing. This proceedings publication from...

  14. Calculated carrier mobility of h-BN/γ-InSe/h-BN van der Waals heterostructures

    Science.gov (United States)

    Kang, P.; Michaud-Rioux, V.; Kong, X.-H.; Yu, G.-H.; Guo, H.

    2017-12-01

    Recent experiments reported excellent transport properties of two-dimensional (2D) van der Waals (vdW) heterostructures made of atomically thin InSe layers encapsulated by two hBN capping layers (ISBN). The carrier mobility of the ISBN films exceeded μ ∼ 1.2× {{10}4} \\text{c}{{\\text{m}}2} {{\\text{V}}-1} {{\\text{s}}-1} at low temperature, much higher than that of pristine InSe films. It has been puzzling why the relatively inert hBN capping layer could so drastically enhance mobility of the ISBN composite. Using a state-of-the-art first principles method, we have calculated phonon limited carrier mobility of 18 different ISBN films and 6 pristine InSe films with different thicknesses, the largest system containing 2212 atoms. The hBN capping layer significantly alters the elastic stiffness coefficient as compared with pure InSe—thus the acoustic phonons in the ISBN composite—giving rise to the observed large mobility of ISBN films. Of the 18 calculated ISBN films, the ones with no strain at the hBN/InSe interface possess the highest electron mobility, reaching 4340~\\text{c}{{\\text{m}}2}~{{\\text{V}}-1}~{{\\text{s}}-1} at room temperature, which could easily go over {{10}4}~\\text{c}{{\\text{m}}2}~{{\\text{V}}-1}~{{\\text{s}}-1} at low temperatures. We conclude that the mechanical properties of the composite 2D vdW ISBN material play the crucial role for inducing the large carrier mobility, a principle that could be applied to many other 2D vdW heterostructures.

  15. Structural Mobility, Exchange Mobility and Subgroup Consistent Mobility Measurement – US–German Mobility Measurements Revisited

    OpenAIRE

    Schluter, C.; D. VAN DE GAER

    2008-01-01

    We formalize the concept of structural mobility and use the framework of subgroup consistent mobility measurement to derive a relative and an absolute measure of mobility that is increasing both in upward structural mobility and exchange mobility. In our empirical illustration, we contribute substantively to the ongoing debate about mobility rankings between the USA and Germany.

  16. Lead iodide perovskite sensitized all-solid-state submicron thin film mesoscopic solar cell with efficiency exceeding 9%.

    KAUST Repository

    Kim, Hui-Seon

    2012-08-21

    We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH(3)NH(3))PbI(3) as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI(2) and deposited onto a submicron-thick mesoscopic TiO(2) film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (J(SC)) exceeding 17 mA/cm(2), an open circuit photovoltage (V(OC)) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH(3)NH(3))PbI(3) NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO(2) film. The use of a solid hole conductor dramatically improved the device stability compared to (CH(3)NH(3))PbI(3) -sensitized liquid junction cells.

  17. Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9%

    Science.gov (United States)

    Kim, Hui-Seon; Lee, Chang-Ryul; Im, Jeong-Hyeok; Lee, Ki-Beom; Moehl, Thomas; Marchioro, Arianna; Moon, Soo-Jin; Humphry-Baker, Robin; Yum, Jun-Ho; Moser, Jacques E.; Grätzel, Michael; Park, Nam-Gyu

    2012-01-01

    We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto a submicron-thick mesoscopic TiO2 film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (JSC) exceeding 17 mA/cm2, an open circuit photovoltage (VOC) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH3NH3)PbI3 NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO2 film. The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells. PMID:22912919

  18. A framework of mobile transaction use: the user’s perspective

    OpenAIRE

    Alqahtani, Mohammed

    2015-01-01

    The remarkable advances of mobile technologies and the prevalence of mobile devices have profoundly transformed telephony systems. They provide functionalities which surpass telephony needs, and which motivate the development of value-added mobile services and functions. The number of mobile phones in use far exceeds any other technical devices that could be used to market, sell, produce, or deliver products and services to consumers. These developments open lucrative opportunities to retaile...

  19. Mobile termination and mobile penetration

    OpenAIRE

    Hurkens, Sjaak; Jeon, Doh-Shin

    2009-01-01

    In this paper, we study how access pricing affects network competition when subscription demand is elastic and each network uses non-linear prices and can apply termination-based price discrimination. In the case of a fixed per minute termination charge, we find that a reduction of the termination charge below cost has two oppos- ing effects: it softens competition but helps to internalize network externalities. The former reduces mobile penetration while the latter boosts it. We find that fi...

  20. Graphene mobility mapping.

    Science.gov (United States)

    Buron, Jonas D; Pizzocchero, Filippo; Jepsen, Peter U; Petersen, Dirch H; Caridad, José M; Jessen, Bjarke S; Booth, Timothy J; Bøggild, Peter

    2015-07-24

    Carrier mobility and chemical doping level are essential figures of merit for graphene, and large-scale characterization of these properties and their uniformity is a prerequisite for commercialization of graphene for electronics and electrodes. However, existing mapping techniques cannot directly assess these vital parameters in a non-destructive way. By deconvoluting carrier mobility and density from non-contact terahertz spectroscopic measurements of conductance in graphene samples with terahertz-transparent backgates, we are able to present maps of the spatial variation of both quantities over large areas. The demonstrated non-contact approach provides a drastically more efficient alternative to measurements in contacted devices, with potential for aggressive scaling towards wafers/minute. The observed linear relation between conductance and carrier density in chemical vapour deposition graphene indicates dominance by charged scatterers. Unexpectedly, significant variations in mobility rather than doping are the cause of large conductance inhomogeneities, highlighting the importance of statistical approaches when assessing large-area graphene transport properties.

  1. A Mobile Learning Module for High School Fieldwork

    Science.gov (United States)

    Hsu, Tzu-Yen; Chen, Che-Ming

    2010-01-01

    Although fieldwork is always cited as an important component of geographic education, there are many obstacles for executing high school fieldwork. Mobile electronic products are becoming popular and some schools are able to acquire these devices for mobile learning. This study attempts to provide a mobile-assisted means of guiding students…

  2. A logistic regression based approach for the prediction of flood warning threshold exceedance

    Science.gov (United States)

    Diomede, Tommaso; Trotter, Luca; Stefania Tesini, Maria; Marsigli, Chiara

    2016-04-01

    A method based on logistic regression is proposed for the prediction of river level threshold exceedance at short (+0-18h) and medium (+18-42h) lead times. The aim of the study is to provide a valuable tool for the issue of warnings by the authority responsible of public safety in case of flood. The role of different precipitation periods as predictors for the exceedance of a fixed river level has been investigated, in order to derive significant information for flood forecasting. Based on catchment-averaged values, a separation of "antecedent" and "peak-triggering" rainfall amounts as independent variables is attempted. In particular, the following flood-related precipitation periods have been considered: (i) the period from 1 to n days before the forecast issue time, which may be relevant for the soil saturation, (ii) the last 24 hours, which may be relevant for the current water level in the river, and (iii) the period from 0 to x hours in advance with respect to the forecast issue time, when the flood-triggering precipitation generally occurs. Several combinations and values of these predictors have been tested to optimise the method implementation. In particular, the period for the precursor antecedent precipitation ranges between 5 and 45 days; the state of the river can be represented by the last 24-h precipitation or, as alternative, by the current river level. The flood-triggering precipitation has been cumulated over the next 18 hours (for the short lead time) and 36-42 hours (for the medium lead time). The proposed approach requires a specific implementation of logistic regression for each river section and warning threshold. The method performance has been evaluated over the Santerno river catchment (about 450 km2) in the Emilia-Romagna Region, northern Italy. A statistical analysis in terms of false alarms, misses and related scores was carried out by using a 8-year long database. The results are quite satisfactory, with slightly better performances

  3. Water splitting-biosynthetic system with CO₂ reduction efficiencies exceeding photosynthesis.

    Science.gov (United States)

    Liu, Chong; Colón, Brendan C; Ziesack, Marika; Silver, Pamela A; Nocera, Daniel G

    2016-06-03

    Artificial photosynthetic systems can store solar energy and chemically reduce CO2 We developed a hybrid water splitting-biosynthetic system based on a biocompatible Earth-abundant inorganic catalyst system to split water into molecular hydrogen and oxygen (H2 and O2) at low driving voltages. When grown in contact with these catalysts, Ralstonia eutropha consumed the produced H2 to synthesize biomass and fuels or chemical products from low CO2 concentration in the presence of O2 This scalable system has a CO2 reduction energy efficiency of ~50% when producing bacterial biomass and liquid fusel alcohols, scrubbing 180 grams of CO2 per kilowatt-hour of electricity. Coupling this hybrid device to existing photovoltaic systems would yield a CO2 reduction energy efficiency of ~10%, exceeding that of natural photosynthetic systems. Copyright © 2016, American Association for the Advancement of Science.

  4. Gusts and shear within hurricane eyewalls can exceed offshore wind turbine design standards

    Science.gov (United States)

    Worsnop, Rochelle P.; Lundquist, Julie K.; Bryan, George H.; Damiani, Rick; Musial, Walt

    2017-06-01

    Offshore wind energy development is underway in the U.S., with proposed sites located in hurricane-prone regions. Turbine design criteria outlined by the International Electrotechnical Commission do not encompass the extreme wind speeds and directional shifts of hurricanes stronger than category 2. We examine a hurricane's turbulent eyewall using large-eddy simulations with Cloud Model 1. Gusts and mean wind speeds near the eyewall of a category 5 hurricane exceed the current Class I turbine design threshold of 50 m s-1 mean wind and 70 m s-1 gusts. Largest gust factors occur at the eye-eyewall interface. Further, shifts in wind direction suggest that turbines must rotate or yaw faster than current practice. Although current design standards omit mention of wind direction change across the rotor layer, large values (15-50°) suggest that veer should be considered.

  5. Future temperature in southwest Asia projected to exceed a threshold for human adaptability

    Science.gov (United States)

    Pal, Jeremy S.; Eltahir, Elfatih A. B.

    2016-02-01

    A human body may be able to adapt to extremes of dry-bulb temperature (commonly referred to as simply temperature) through perspiration and associated evaporative cooling provided that the wet-bulb temperature (a combined measure of temperature and humidity or degree of `mugginess’) remains below a threshold of 35 °C. (ref. ). This threshold defines a limit of survivability for a fit human under well-ventilated outdoor conditions and is lower for most people. We project using an ensemble of high-resolution regional climate model simulations that extremes of wet-bulb temperature in the region around the Arabian Gulf are likely to approach and exceed this critical threshold under the business-as-usual scenario of future greenhouse gas concentrations. Our results expose a specific regional hotspot where climate change, in the absence of significant mitigation, is likely to severely impact human habitability in the future.

  6. Problem-based learning in children's nursing: transcending doubts to exceeding expectations.

    Science.gov (United States)

    Raftery, Sara E C; Clynes, Mary P; O'Neill, Colleen; Ward, Emer; Coyne, Imelda

    2010-01-01

    Problem-based learning (PBL) is well established in health education. It is regarded as a constructionist approach to education that emphasizes students' active engagement with the learning process, self-direction, and learning in a meaningful context. This article details the experiences of nurse lecturers in one university in the Republic of Ireland during the introduction of a PBL module to students enrolled in a higher diploma in children's nursing program. All lecturers attended a three-day training program on the principles and processes of PBL. The lecturers, all experienced nurse educators, had no prior experience in implementing PBL. Data collection involved the use of reflective journals and group meetings. Thematic content analysis revealed key themes that chart the journey from transcending doubts to exceeding expectations of the PBL process.

  7. Gusts and Shear Within Hurricane Eyewalls Can Exceed Offshore Wind-Turbine Design Standards

    CERN Document Server

    Worsnop, Rochelle P; Bryan, George H; Damiani, Rick; Musial, Walt

    2016-01-01

    Offshore wind energy development is underway in the U.S., with proposed sites located in hurricane-prone regions. Turbine design criteria outlined by the International Electrotechnical Commission do not encompass the extreme wind speeds and directional shifts of hurricanes stronger than a Category 2. We examine the most turbulent portion of a hurricane (the eyewall) using large-eddy simulations with Cloud Model 1 (CM1). Gusts and mean wind speeds near the eyewall exceed the current design threshold of 50 m s-1 mean wind and 70 m s-1 gusts for Class I turbines. Gust factors are greatest at the eye-eyewall interface. Further, shifts in wind direction at wind turbine hub height suggest turbines must rotate into the wind faster than current practice. Although current design standards omit mention of wind direction change across the rotor layer, large values (15-50 deg) suggest that veer should be considered in design standards.

  8. Most American Academy of Orthopaedic Surgeons' online patient education material exceeds average patient reading level.

    Science.gov (United States)

    Eltorai, Adam E M; Sharma, Pranav; Wang, Jing; Daniels, Alan H

    2015-04-01

    Advancing health literacy has the potential to improve patient outcomes. The American Academy of Orthopaedic Surgeons' (AAOS) online patient education materials serve as a tool to improve health literacy for orthopaedic patients; however, it is unknown whether the materials currently meet the National Institutes of Health/American Medical Association's recommended sixth grade readability guidelines for health information or the mean US adult reading level of eighth grade. The purposes of this study were (1) to evaluate the mean grade level readability of online AAOS patient education materials; and (2) to determine what proportion of the online materials exceeded recommended (sixth grade) and mean US (eighth grade) reading level. Reading grade levels for 99.6% (260 of 261) of the online patient education entries from the AAOS were analyzed using the Flesch-Kincaid formula built into Microsoft Word software. Mean grade level readability of the AAOS patient education materials was 9.2 (SD ± 1.6). Two hundred fifty-one of the 260 articles (97%) had a readability score above the sixth grade level. The readability of the AAOS articles exceeded the sixth grade level by an average of 3.2 grade levels. Of the 260 articles, 210 (81%) had a readability score above the eighth grade level, which is the average reading level of US adults. Most of the online patient education materials from the AAOS had readability levels that are far too advanced for many patients to comprehend. Efforts to adjust the readability of online education materials to the needs of the audience may improve the health literacy of orthopaedic patients. Patient education materials can be made more comprehensible through use of simpler terms, shorter sentences, and the addition of pictures. More broadly, all health websites, not just those of the AAOS, should aspire to be comprehensible to the typical reader.

  9. How much Baltic salmon can be consumed without exceeding the tolerable safety limit ?

    Energy Technology Data Exchange (ETDEWEB)

    Kristiansen, H.R. [Mobile Nutrients Ltd. (Denmark)

    2004-09-15

    Because Baltic salmon is a top predator preying on sprat, herring and tobis, it is very vulnerable to contamination with dioxin and PCBs. The EU safety limit (SL) for fish is 4 picogram (pg) WHOTEQ g{sup -1} fresh fish. In April 2004, Danish commercial salmon fishing was banned to in the Baltic sea around Bornholm and Gotland (mainly ICES areas 25, 26), because the Food Administration reported dioxin levels exceeding the intervention level of 3 pg g{sup -1} fresh salmon. Their report was based on data from 10 individual salmon, and 3 pooled samples, each with 10 salmon. Since dioxins are widespread in the environment, the human population face a trade off to produce sufficient food that is safe to eat and avoid eating contaminated food. The world population is increasing, and the demand for healthy food is steadily increasing. Consequently, there is a need for risk assessments, where the consequences of eating foods with different grades of contamination is evaluated. The evaluation must be based on data of high quality, and because dioxin accumulation is a slow proces, the risk assessments should consider long time periods of months and years instead of days and weeks. The purpose of the present study is to evaluate the statistical variation of dioxin data from Baltic herring and salmon. The data are used to calculate the quantity of herring and salmon, that humans of different body weight can eat without exceeding the tolerable daily intake (TDI). (In dietary recommendations exposure from dairy products etc. must also be taken into account). A PCDD/F box model is proposed that subtract losses during cooking and postprandially.

  10. Was it worthwhile? Where have the benefits of rooftop solar photovoltaic generation exceeded the cost?

    Science.gov (United States)

    Vaishnav, Parth; Horner, Nathaniel; Azevedo, Inês L.

    2017-09-01

    We estimate the lifetime magnitude and distribution of the private and public benefits and costs of currently installed distributed solar PV systems in the United States. Using data for recently-installed systems, we estimate the balance of benefits and costs associated with installing a non-utility solar PV system today. We also study the geographical distribution of the various subsidies that are made available to owners of rooftop solar PV systems, and compare it to distributions of population and income. We find that, after accounting for federal subsidies and local rebates and assuming a discount rate of 7%, the private benefits of new installations will exceed private costs only in seven of the 19 states for which we have data and only if customers can sell excess power to the electric grid at the retail price. These states are characterized by abundant sunshine (California, Texas and Nevada) or by high electricity prices (New York). Public benefits from reduced air pollution and climate change impact exceed the costs of the various subsidies offered system owners for less than 10% of the systems installed, even assuming a 2% discount rate. Subsidies flowed disproportionately to counties with higher median incomes in 2006. In 2014, the distribution of subsidies was closer to that of population income, but subsidies still flowed disproportionately to the better-off. The total, upfront, subsidy per kilowatt of installed capacity has fallen from 5200 in 2006 to 1400 in 2014, but the absolute magnitude of subsidy has soared as installed capacity has grown explosively. We see considerable differences in the balance of costs and benefits even within states, indicating that local factors such as system price and solar resource are important, and that policies (e.g. net metering) could be made more efficient by taking local conditions into account.

  11. Mobility Bibliography.

    Science.gov (United States)

    1981-11-01

    IV-419 Strauss, A.M. - V-55 Stuller, J. - IV-470 Stuller, J.G. - IV-457 Sugarman , R.C. - IV-707 Suhier, S.A. - IV-540 Sullivan, E. - 111-214 Sullivan...military vehicle mobility 148 110. AU - Brannon, W.; David , R.H.; Hodges, W., Jr.; Janowski, W.R. TI - Design and development of the twister testbed SO...OS - Aluminum Co of America Alcoa Center PA, David W. Taylor Naval Ship Research and Development Center, Bethesda, MD SO - 20 Feb 76, 59 p, ADA024262

  12. Downwardly mobile

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-01-01

    P & H Mining Equipment has produced the 250XP rotary blasthole drill, its first `clean sheet` drill after eight years of upgrading the line of large rotaries it acquired from Gardner Denver in 1991. A prototype has been working on an Australian coal mine since June 1998. A further two units of the 250XP are being erected at a diamond mine in Botswana for start-up in January 1999 and another will begin drilling at a Wyoming, USA coal mine in February. The drill is a highly mobile, heavy duty, highly reliable diesel/hydraulic drill weighing 113,500 kg and can drill holes at angles up to 30 degrees.

  13. Wapice News Mobile Application

    OpenAIRE

    Söylemez, Ilke

    2017-01-01

    Since the mobile phones started to have an increasingly significant role in daily life, the mobile application development also started to be an important area in the software industry. The problem for mobile application developers is to develop a mobile application which supports all the devices and platforms on the market. This issue created a need for cross platform mobile applications. The cross platform mobile development refers to the development of mobile applications that could be use...

  14. Evaluation of AlGaN/GaN metal-oxide-semicondutor high-electron mobility transistors with plasma-enhanced atomic layer deposition HfO2/AlN date dielectric for RF power applications

    Science.gov (United States)

    Chiu, Yu Sheng; Luc, Quang Ho; Lin, Yueh Chin; Chien Huang, Jui; Dee, Chang Fu; Yeop Majlis, Burhanuddin; Chang, Edward Yi

    2017-09-01

    A plasma enhanced atomic layer deposition (PEALD) HfO2/AlN dielectric stack was used as the gate dielectric for AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs) for high-frequency power device applications. The capacitance-voltage (C-V) curves of the HfO2/AlN/GaN MOS capacitor (MOSCAP) showed a small frequency dispersion along with a very small hysteresis (˜50 mV). Moreover, the interface trap density (D it) was calculated to be 2.7 × 1011 cm-2 V-1 s-1 at 150 °C. Using PEALD-AlN as the interfacial passivation layer (IPL), the drain current of the HfO2/AlN MOS-HEMTs increased by about 46% and the gate leakage current decreased by six orders of magnitude as compared with those of the conventional Schottky gate AlGaN/GaN HEMTs processed using the same epitaxial wafer. The 0.3-µm-gate-length HfO2/AlN/AlGaN/GaN MOS-HEMTs demonstrated a 2.88 W/mm output power, a 23 dB power gain, a 30.2% power-added efficiency at 2.4 GHz, and an improved device linearity as compared with the conventional AlGaN/GaN HEMTs. The third-order intercept point at the output (OIP3) of the MOS-HEMTs was 28.4 as compared with that of 26.5 for the conventional GaN HEMTs. Overall, the MOS-HEMTs with a HfO2/AlN gate stack showed good potential for high-linearity RF power device applications.

  15. The Social & Mobile Learning Experiences of Students Using Mobile E-Books

    Science.gov (United States)

    Kissinger, Jeff S.

    2013-01-01

    This research was designed to explore the learning experiences of state college students using mobile electronic textbook (e-book) readers. The purpose of the study was to build a rich description of how students used e-books delivered on mobile computing devices for college-level, introductory

  16. Advertising on mobile applications

    OpenAIRE

    Sobolevsky, Alexandr

    2015-01-01

    The article analyzes the new method of mobile advertising. Advertising in mobile applications - a subspecies of mobile marketing, where advertising is distributed using mobile phones and smartphones. Ad placement is going on inside of applications and games for smartphones. It has a high potential due to the large number of mobile phone users (over 6.5 billion in 2013).

  17. Neurological and neurophysiological examinations of workers exposed to arsenic levels exceeding hygiene standards

    Directory of Open Access Journals (Sweden)

    Halina Sińczuk-Walczak

    2014-12-01

    Full Text Available Objectives: The assessment of the neurotoxic effect of arsenic (As and its inorganic compounds is still the subject of interest due to a growing As application in a large array of technologies and the need to constantly verify the principles of prevention and technological parameters. The aim of this study was to determine the status of the nervous system (NS in workers exposed to As at concentrations exceeding hygiene standards (Threshold Limit Values (TLV – 10 μg/m3, Biological Exposure Index (BEI – 35 μg/l and to analyze the relationship between the NS functional state, species of As in urine and As levels in the workplace air. Material and Methods: The study group comprised 21 men (mean age: 47.43±7.59 employed in a copper smelting factory (mean duration of employment: 22.29±11.09. The control group comprised 16 men, matched by age and work shifts. Arsenic levels in the workplace air (As-A ranged from 0.7 to 92.3 μg/m3; (M = 25.18±28.83. The concentration of total arsenic in urine (Astot-U ranged from 17.35 to 434.68 μg/l (M = 86.82±86.6. Results: Syndrome of peripheral nervous system (PNS was manifested by extremity fatigue (28.6%, extremity pain (33.3% and paresthesia in the lower extremities (33.3%, as well as by neuropathy-type mini-symptoms (23.8%. Electroneurographic (ENeG tests of peroneal nerves showed significantly decreased response amplitude with normal values of motor conduction velocity (MCV. Stimulation of sural nerves revealed a significantly slowed sensory conduction velocity (SCV and decreased sensory potential amplitude. Neurophysiological parameters and the results of biological and environmental monitoring showed a relationship between Astot, AsIII (trivalent arsenic, the sum of iAs (AsIII+AsV (pentavalent arsenic+MMA (monomethylarsonic acid concentration in urine and As levels in the air. Conclusions: The results of the study demonstrate that occupational exposure to inorganic arsenic levels exceeding hygiene

  18. What could have caused pre-industrial biomass burning emissions to exceed current rates?

    Directory of Open Access Journals (Sweden)

    G. R. van der Werf

    2013-01-01

    Full Text Available Recent studies based on trace gas mixing ratios in ice cores and charcoal data indicate that biomass burning emissions over the past millennium exceeded contemporary emissions by up to a factor of 4 for certain time periods. This is surprising because various sources of biomass burning are linked with population density, which has increased over the past centuries. We have analysed how emissions from several landscape biomass burning sources could have fluctuated to yield emissions that are in correspondence with recent results based on ice core mixing ratios of carbon monoxide (CO and its isotopic signature measured at South Pole station (SPO. Based on estimates of contemporary landscape fire emissions and the TM5 chemical transport model driven by present-day atmospheric transport and OH concentrations, we found that CO mixing ratios at SPO are more sensitive to emissions from South America and Australia than from Africa, and are relatively insensitive to emissions from the Northern Hemisphere. We then explored how various landscape biomass burning sources may have varied over the past centuries and what the resulting emissions and corresponding CO mixing ratio at SPO would be, using population density variations to reconstruct sources driven by humans (e.g., fuelwood burning and a new model to relate savanna emissions to changes in fire return times. We found that to match the observed ice core CO data, all savannas in the Southern Hemisphere had to burn annually, or bi-annually in combination with deforestation and slash and burn agriculture exceeding current levels, despite much lower population densities and lack of machinery to aid the deforestation process. While possible, these scenarios are unlikely and in conflict with current literature. However, we do show the large potential for increased emissions from savannas in a pre-industrial world. This is mainly because in the past, fuel beds were probably less fragmented compared to the

  19. Mobile video with mobile IPv6

    CERN Document Server

    Minoli, Daniel

    2012-01-01

    Increased reliance on mobile devices and streaming of video content are two of the most recent changes that have led those in the video distribution industry to be concerned about the shifting or erosion of traditional advertising revenues. Infrastructure providers also need to position themselves to take advantage of these trends. Mobile Video with Mobile IPv6provides an overview of the current mobile landscape, then delves specifically into the capabilities and operational details of IPv6. The book also addresses 3G and 4G services, the application of Mobile IPv6 to streaming and other mobil

  20. Matter-wave interference of particles selected from a molecular library with masses exceeding 10,000 amu.

    Science.gov (United States)

    Eibenberger, Sandra; Gerlich, Stefan; Arndt, Markus; Mayor, Marcel; Tüxen, Jens

    2013-09-21

    The quantum superposition principle, a key distinction between quantum physics and classical mechanics, is often perceived as a philosophical challenge to our concepts of reality, locality or space-time since it contrasts with our intuitive expectations with experimental observations on isolated quantum systems. While we are used to associating the notion of localization with massive bodies, quantum physics teaches us that every individual object is associated with a wave function that may eventually delocalize by far more than the body's own extension. Numerous experiments have verified this concept at the microscopic scale but intuition wavers when it comes to delocalization experiments with complex objects. While quantum science is the uncontested ideal of a physical theory, one may ask if the superposition principle can persist on all complexity scales. This motivates matter-wave diffraction and interference studies with large compounds in a three-grating interferometer configuration which also necessitates the preparation of high-mass nanoparticle beams at low velocities. Here we demonstrate how synthetic chemistry allows us to prepare libraries of fluorous porphyrins which can be tailored to exhibit high mass, good thermal stability and relatively low polarizability, which allows us to form slow thermal beams of these high-mass compounds, which can be detected using electron ionization mass spectrometry. We present successful superposition experiments with selected species from these molecular libraries in a quantum interferometer, which utilizes the diffraction of matter-waves at an optical phase grating. We observe high-contrast quantum fringe patterns of molecules exceeding a mass of 10,000 amu and having 810 atoms in a single particle.

  1. Mobile shearography

    Science.gov (United States)

    Kalms, Michael; Jueptner, Werner

    2005-04-01

    By reason of their sensitivity, accuracy and non-contact as well as non-destructive characteristics, modern optical methods such as digital speckle shearography have found an increasing interest for NDT applications on the factory floor. With new carbon filter technologies and other lightweight constructions in aircraft and automotive manufacturing, adapted examination designs and especially developed testing methods are necessary. Shearography as a coherent optical method has been widely accepted as an useful NDT tool. It is a robust interferometric method to determine locations with maximum stress on various material structures. However, limitations of this technique can be found in the bulky equipment components, the interpretation of the complex sherographic result images and at the work with non-cooperative surfaces (dark absorber, bright shining reflectors). We report a mobile shearography system that was especially designed for investigations at aircraft and automotive constructions.

  2. Joint mobilization.

    Science.gov (United States)

    Saunders, Deborah Gross; Walker, J Randy; Levine, David

    2005-11-01

    Therapeutic touch has been used in human beings to soothe aches and pains. Most dogs also seem to enjoy being touched. Manual therapy techniques are skilled hand movements intended to improve tissue extensibility; increase range of motion; induce relaxation; mobilize or manipulate soft tissue and joints; modulate pain; and reduce soft tissue swelling, inflammation, or restriction. The intent of this article is to provide an overview of the principles of manual therapy, followed by selected treatment techniques for the hip, stifle, elbow, shoulder, carpus.and thoracic and lumbar spine. The techniques of G.D. Maitland, an Australian physical therapist who developed a clinically based approach in the 1960s and 1970s, are emphasized.

  3. [Social mobilization].

    Science.gov (United States)

    Bop, C

    1990-04-01

    One of the principal recommendations from Alma Ata and the Bamako Initiative was the need for communities to take responsibility for their own health--a recommendation that still remains unmet and in need of reform in Africa because of the severe economic recession and lack of resources allocated for health care in the region. The mobilization of communities "is the opposite of passivity and submission." People must demystify the notion that health care is the exclusive right of health professionals and should realize that they themselves can bring about changes from the household to the village levels; community mobilization is an integral component of development planning. African societies have developed very centralized structures requiring changes that only their own communities can bring about. Because women remain the principal agents for the family's health they should be informed, about the multiple dimensions leading to good health care to enable them to provide the rest of the family with good nourishment and health care follow-up. Children are a vulnerable and important group that require preventive care. A UNICEF experiment in Senegal is training 10-13 year old school children to visit the parents of 5 children, inform them about vaccinating their children, and to follow-up on their activities with these "adopted families." The need for short and long-term IEC interventions in Africa are a priority and effective strategies must be found to reach the majority of the rural populations where all obstacles such as the lack of infrastructure and illiteracy exist. Mali has used traditional theatre "Koteba" to reach the rural populations on a variety of health issues such as oral rehydration and diarrhea as well as the Rural Audio Library (it used cassettes rather than books) to reach villagers in their own languages. The worst obstacle facing Africa today is the refusal of officials in power to allow people to manage their own lives, of which health is a

  4. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  5. Super-strong materials for temperatures exceeding 2000 °C

    Science.gov (United States)

    Silvestroni, Laura; Kleebe, Hans-Joachim; Fahrenholtz, William G.; Watts, Jeremy

    2017-01-01

    Ceramics based on group IV-V transition metal borides and carbides possess melting points above 3000 °C, are ablation resistant and are, therefore, candidates for the design of components of next generation space vehicles, rocket nozzle inserts, and nose cones or leading edges for hypersonic aerospace vehicles. As such, they will have to bear high thermo-mechanical loads, which makes strength at high temperature of great importance. While testing of these materials above 2000 °C is necessary to prove their capabilities at anticipated operating temperatures, literature reports are quite limited. Reported strength values for zirconium diboride (ZrB2) ceramics can exceed 1 GPa at room temperature, but these values rapidly decrease, with all previously reported strengths being less than 340 MPa at 1500 °C or above. Here, we show how the strength of ZrB2 ceramics can be increased to more than 800 MPa at temperatures in the range of 1500-2100 °C. These exceptional strengths are due to a core-shell microstructure, which leads to in-situ toughening and sub-grain refinement at elevated temperatures. Our findings promise to open a new avenue to designing materials that are super-strong at ultra-high temperatures.

  6. On the probability of exceeding allowable leak rates through degraded steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Cizelj, L.; Sorsek, I. [Jozef Stefan Institute, Ljubljana (Slovenia); Riesch-Oppermann, H. [Forschungszentrum Karlsruhe (Germany)

    1997-02-01

    This paper discusses some possible ways of predicting the behavior of the total leak rate through the damaged steam generator tubes. This failure mode is of special concern in cases where most through-wall defects may remain In operation. A particular example is the application of alternate (bobbin coil voltage) plugging criterion to Outside Diameter Stress Corrosion Cracking at the tube support plate intersections. It is the authors aim to discuss some possible modeling options that could be applied to solve the problem formulated as: Estimate the probability that the sum of all individual leak rates through degraded tubes exceeds the predefined acceptable value. The probabilistic approach is of course aiming at reliable and computationaly bearable estimate of the failure probability. A closed form solution is given for a special case of exponentially distributed individual leak rates. Also, some possibilities for the use of computationaly efficient First and Second Order Reliability Methods (FORM and SORM) are discussed. The first numerical example compares the results of approximate methods with closed form results. SORM in particular shows acceptable agreement. The second numerical example considers a realistic case of NPP in Krsko, Slovenia.

  7. Stratospheric Intrusion-Influenced Ozone Air Quality Exceedances Investigated in the NASA MERRA-2 Reanalysis

    Science.gov (United States)

    Knowland, K. E.; Ott, L. E.; Duncan, B. N.; Wargan, K.

    2017-10-01

    Stratospheric intrusions have been the interest of decades of research for their ability to bring stratospheric ozone (O3) into the troposphere with the potential to enhance surface O3 concentrations. However, these intrusions have been misrepresented in models and reanalyses until recently, as the features of a stratospheric intrusion are best identified in horizontal resolutions of 50 km or smaller. NASA's Modern-Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2) reanalysis is a publicly available high-resolution data set (˜50 km) with assimilated O3 that characterizes O3 on the same spatiotemporal resolution as the meteorology. We demonstrate the science capabilities of the MERRA-2 reanalysis when applied to the evaluation of stratospheric intrusions that impact surface air quality. This is demonstrated through a case study analysis of stratospheric intrusion-influenced O3 exceedances in spring 2012 in Colorado, using a combination of observations, the MERRA-2 reanalysis and Goddard Earth Observing System Model, Version 5 simulations.

  8. Precipitation extreme changes exceeding moisture content increases in MIROC and IPCC climate models.

    Science.gov (United States)

    Sugiyama, Masahiro; Shiogama, Hideo; Emori, Seita

    2010-01-12

    Precipitation extreme changes are often assumed to scale with, or are constrained by, the change in atmospheric moisture content. Studies have generally confirmed the scaling based on moisture content for the midlatitudes but identified deviations for the tropics. In fact half of the twelve selected Intergovernmental Panel on Climate Change (IPCC) models exhibit increases faster than the climatological-mean precipitable water change for high percentiles of tropical daily precipitation, albeit with significant intermodel scatter. Decomposition of the precipitation extreme changes reveals that the variations among models can be attributed primarily to the differences in the upward velocity. Both the amplitude and vertical profile of vertical motion are found to affect precipitation extremes. A recently proposed scaling that incorporates these dynamical effects can capture the basic features of precipitation changes in both the tropics and midlatitudes. In particular, the increases in tropical precipitation extremes significantly exceed the precipitable water change in Model for Interdisciplinary Research on Climate (MIROC), a coupled general circulation model with the highest resolution among IPCC climate models whose precipitation characteristics have been shown to reasonably match those of observations. The expected intensification of tropical disturbances points to the possibility of precipitation extreme increases beyond the moisture content increase as is found in MIROC and some of IPCC models.

  9. 137Cs activity concentration in wild boar meat may still exceed the permitted levels

    Directory of Open Access Journals (Sweden)

    Rachubik J.

    2012-04-01

    Full Text Available The radiocaesium activity concentration may still remain high in natural products such as game meat, wild mushrooms, and forest berries even more than two decades after the Chernobyl accident. The results of regular control studies of game meat conducted in Poland showed wild boars as the most contaminated game animals. It is well documented that some mushrooms, readily consumed by animals, show high ability to accumulate caesium radioisotopes. Bay bolete, one of the most wide-spread mushroom species in Poland, reveals a unique radiocaesium accumulation feature. Moreover, deer truffle, containing also particularly high levels of radiocaesium, could be another radionu-clide source for wild boars. Furthermore, animals consuming deer truffles could digest contaminated soil components. Among 94 wild boar meat samples analysed in 2008–2009, two exceeded the permitted level. Hence, some precautions should be taken in the population with an elevated intake of wild boar meat. Moreover, since each hunted wild boar is examined for the presence of Trichinella larvae, regular measurements of radiocaesium concentrations in these animals may be advisable for enhancing consumer safety.

  10. Globalization and international student mobility:a network analysis

    OpenAIRE

    Shields, Robin

    2013-01-01

    This article analyzes changes to the network of international student mobility in higher education over a 10-year period (1999–2008). International student flows have increased rapidly, exceeding 3 million in 2009, and extensive data on mobility provide unique insight into global educational processes. The analysis is informed by three theoretical conceptualizations of globalization: neoliberalism, critical perspectives (e.g., world-systems analysis and poststructuralism), and world culture t...

  11. Mobile Inquiry Based Learning

    NARCIS (Netherlands)

    Specht, Marcus

    2012-01-01

    Specht, M. (2012, 8 November). Mobile Inquiry Based Learning. Presentation given at the Workshop "Mobile inquiry-based learning" at the Mobile Learning Day 2012 at the Fernuniversität Hagen, Hagen, Germany.

  12. MOBILITY: A SYSTEMS APPROACH

    Directory of Open Access Journals (Sweden)

    Mykola I. Striuk

    2015-10-01

    Full Text Available A comprehensive study on the problem of mobility in the socio-educational and technical systems was carried out: the evolution of the concept of mobility in scientific sources of XIX–XXI centuries was analyzed and the new sources on the issue of mobility introduced into scientific circulation, the interrelation of the types of mobility in the socio-pedagogical and technical systems are theoretically grounded, an integrative model of mobility in the information society is proposed. The major trends in academic mobility are identified (the transition from student mobility to mobility programs and educational services providers, the new mobility programs (franchising, double/joint degrees, combinations, nostrification etc. are characterized. The new types of mobility providers are reviewed and attention is focused on virtual universities that are now the basis of virtual mobility of students and activities which are based on the use of new ICT in higher education, especially – the Internet and mobile learning environments.

  13. Micro Mobility Marketing

    DEFF Research Database (Denmark)

    Hosbond, Jens Henrik; Skov, Mikael B.

    2008-01-01

    Mobile marketing refers to marketing of services or goods using mobile technology and mobile marketing holds potentially great economical opportunities. Traditionally, mobile marketing has been viewed as mobility in the large taking place virtually anywhere, anytime. Further, research shows...... considerable number of studies on push-based SMS mobile marketing campaigns. This paper explores a related yet different form of mobile marketing namely micro mobility marketing. Micro mobility marketing denotes mobility in the small, meaning that promotion of goods takes place within a circumscribed location......, in our case a medium-sized retail supermarket. Two prototypes based on push and pull marketing strategies are implemented and evaluated. Taking outset in a synthesis of central issues in contemporary research on mobile marketing, we discuss their role in micro mobility marketing to point to similarities...

  14. Abrechnung mobiler Dienste im Mobile Payment Referenzmodell

    OpenAIRE

    Pousttchi, Key

    2006-01-01

    Abrechnung mobiler Dienste im Mobile Payment Referenzmodell / K. Pousttchi, D. G. Wiedemann. - In: Handbuch E-Money, E-Payment & M-Payment / Thomas Lammer (Hrsg.). - Heidelberg : Physica-Verl., 2006. - S. 363-377

  15. Cooperating mobile robots

    Science.gov (United States)

    Harrington, John J.; Eskridge, Steven E.; Hurtado, John E.; Byrne, Raymond H.

    2004-02-03

    A miniature mobile robot provides a relatively inexpensive mobile robot. A mobile robot for searching an area provides a way for multiple mobile robots in cooperating teams. A robotic system with a team of mobile robots communicating information among each other provides a way to locate a source in cooperation. A mobile robot with a sensor, a communication system, and a processor, provides a way to execute a strategy for searching an area.

  16. Mobile high-resolution time-of-flight mass spectrometer for in-situ analytics

    Energy Technology Data Exchange (ETDEWEB)

    Lang, Johannes; Ebert, Jens [II. Physikalisches Institut, JLU, Giessen (Germany); Dickel, Timo; Geissel, Hans; Plass, Wolfgang; Scheidenberger, Christoph [II. Physikalisches Institut, JLU, Giessen (Germany); GSI, Darmstadt (Germany)

    2011-07-01

    A compact multiple-reflection time-of-flight mass spectrometer (MR-TOF-MS) has been developed. For the first time it allows for mass measurements with a resolving power exceeding 100000 and sub ppm accuracy in a mobile device. Thus it allows to resolve isobars and enables to accurately determine the composition and structure of biomolecules. The MR-TOF-MS consists of an atmospheric pressure interface for DESI and REIMS, ion cooler, ion trap, time-of-flight analyzer, MCP detector and DAQ. Vacuum system components, power supplies as well as electronics are mounted together with the ion optical spectrometer parts on a single frame with a total volume of 0.8 m{sup 3}. Applications of the device within the AmbiProbe research program include in-situ mass spectrometry such as real-time tissue recognition in electrosurgery, identification of mycotoxins and analysis of soil samples for environmental studies.

  17. Recycling of fresh concrete exceeding and wash water in concrete mixing plants

    Directory of Open Access Journals (Sweden)

    Férriz Papí, J. A.

    2014-03-01

    Full Text Available The exceeding concrete and washing equipment water are a matter to solve in concrete production. This paper explains several possibilities for recycling and analyses the products obtained with one recycling equipment. The objective of this work is to study the possibility to increase the percentage of recycling in new mixes. The developed study relates wash water density and fine particles content. Besides, mortar and concrete samples were tested introducing different quantities of these fine particles, substituting cement, sand or only as an addition. Consistency, compressive strength, setting time, absorption, and capillarity were tested. The results indicated an improvement of the studied properties in some percentages when substituting sand. It confirms the possibility to introduce larger quantities of wash water in new concrete mixes, with corrections in sand quantity depending on water density.Los hormigones frescos sobrantes y aguas procedentes de la limpieza de equipos son un inconveniente a resolver en las plantas de hormigón. Este artículo explica varias posibilidades de reciclado y analiza los productos obtenidos en un equipo reciclador concreto, con el objetivo de estudiar el incremento del porcentaje de reciclaje en nuevas amasadas. El estudio realizado relaciona la densidad del agua de lavado y el contenido de partículas finas. Además, ensaya muestras de mortero y hormigón realizando sustituciones de estas partículas finas por cemento, arena o simplemente como adición. Determina consistencia, resistencia a compresión, principio y fin de fraguado, absorción y capilaridad. Los resultados indicaron un incremento general de las propiedades estudiadas en algunos porcentajes de sustitución por arena. Ello confirma la posibilidad de introducir mayores cantidades de agua de lavado en nuevas amasadas de hormigón, mediante correcciones en la dosificación de arena en función de la densidad del agua.

  18. Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area.

    Science.gov (United States)

    Knösel, Michael; Bojes, Mariana; Jung, Klaus; Ziebolz, Dirk

    2012-05-01

    There is a paucity of information with regard to the susceptibility of iatrogenic white spot lesion formation after inattentive, surplus orthodontic etching with 30% phosphoric acid and the subsequent provision or absence of adequate oral hygiene. Ninety sound enamel specimens were randomly allocated to 6 trial groups (n = 15 each) for etching with 30% phosphoric acid for either 15 seconds and standardized daily enamel brushing or no brushing, etching for 30 seconds with daily brushing or no brushing, or nonetched controls with brushing or no brushing. Nutritive acidic assaults were simulated by demineralization cycles 3 times per day for 1 hour with interim storage in artificial saliva. Lesion depths in terms of percentage of fluorescence loss (delta F, delta Q) and lesion extension compared with the baseline were assessed by using quantitative light-induced fluorescence after 2, 7, 14, 21, and 42 days. Etching duration, trial time elapse, and oral hygiene, as well as the significance of factor interactions, were analyzed with 3-way analysis of variance (α = 5%). The impact of the factors of enamel brushing, trial time elapse, and etching each had a comparably significant effect on lesion progression. The effect of surplus etching on white spot lesion formation was significantly enhanced by the simultaneous absence of enamel brushing and also the progression of trial time. The combination of 30 seconds of surplus etching with inadequate oral hygiene was especially detrimental. Excessive surplus orthodontic etching of the complete labial enamel surface, instead of the bracket bases only, must be avoided to prevent iatrogenic white spot lesions. Etching times not exceeding 15 seconds are favorable. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  19. [Increased susceptibility for white spot lesions by surplus orthodontic etching exceeding bracket base area].

    Science.gov (United States)

    Knösel, Michael; Bojes, Mariana; Jung, Klaus; Ziebolz, Dirk; Renger, Stéphane

    2015-09-01

    There is a paucity of information with regard to the susceptibility of iatrogenic white spot lesion formation after inattentive, surplus orthodontic etching with 30% phosphoric acid and the subsequent provision or absence of adequate oral hygiene. Ninety sound enamel specimens were randomly allocated to 6 trial groups (N = 15 each) for etching with 30% phosphoric acid for either 15 seconds and standardized daily enamel brushing or no brushing, etching for 30 seconds with daily brushing or no brushing, or nonetched controls with brushing or no brushing. Nutritive acidic assaults were simulated by demineralization cycles 3 times per day for 1 hour with interim storage in artificial saliva. Lesion depths in terms of percentage of fluorescence loss (delta F, delta Q) and lesion extension compared with the baseline were assessed by using quantitative light-induced fluorescence after 2, 7, 14, 21, and 42 days. Etching duration, trial time elapse, and oral hygiene, as well as the significance of factor interactions, were analyzed with 3-way analysis of variance (α=5%). The impact of the factors of enamel brushing, trial time elapse, and etching each had a comparably significant effect on lesion progression. The effect of surplus etching on white spot lesion formation was significantly enhanced by the simultaneous absence of enamel brushing and also the progression of trial time. The combination of 30 seconds of surplus etching with inadequate oral hygiene was especially detrimental. Excessive surplus orthodontic etching of the complete labial enamel surface, instead of the bracket bases only, must be avoided to prevent iatrogenic white spot lesions. Etching times not exceeding 15 seconds are favorable. © EDP Sciences, SFODF, 2015.

  20. A Service Oriented Architecture to Integrate Mobile Assessment in Learning Management Systems

    Science.gov (United States)

    Riad, A. M.; El-Ghareeb, H. A.

    2008-01-01

    Mobile Learning (M-Learning) is an approach to E-Learning that utilizes mobile devices. Learning Management System (LMS) should enable M-Learning. Unfortunately, M-Learning is not the same at each educational institution. Assessment is one of the learning activities that can be achieved electronically and via mobile device. Mobile assessment…

  1. The Electronic Patient Reported Outcome Tool: Testing Usability and Feasibility of a Mobile App and Portal to Support Care for Patients With Complex Chronic Disease and Disability in Primary Care Settings

    Science.gov (United States)

    Gill, Ashlinder; Khan, Anum Irfan; Hans, Parminder Kaur; Kuluski, Kerry; Cott, Cheryl

    2016-01-01

    Background People experiencing complex chronic disease and disability (CCDD) face some of the greatest challenges of any patient population. Primary care providers find it difficult to manage multiple discordant conditions and symptoms and often complex social challenges experienced by these patients. The electronic Patient Reported Outcome (ePRO) tool is designed to overcome some of these challenges by supporting goal-oriented primary care delivery. Using the tool, patients and providers collaboratively develop health care goals on a portal linked to a mobile device to help patients and providers track progress between visits. Objectives This study tested the usability and feasibility of adopting the ePRO tool into a single interdisciplinary primary health care practice in Toronto, Canada. The Fit between Individuals, Fask, and Technology (FITT) framework was used to guide our assessment and explore whether the ePRO tool is: (1) feasible for adoption in interdisciplinary primary health care practices and (2) usable from both the patient and provider perspectives. This usability pilot is part of a broader user-centered design development strategy. Methods A 4-week pilot study was conducted in which patients and providers used the ePRO tool to develop health-related goals, which patients then monitored using a mobile device. Patients and providers collaboratively set goals using the system during an initial visit and had at least 1 follow-up visit at the end of the pilot to discuss progress. Focus groups and interviews were conducted with patients and providers to capture usability and feasibility measures. Data from the ePRO system were extracted to provide information regarding tool usage. Results Six providers and 11 patients participated in the study; 3 patients dropped out mainly owing to health issues. The remaining 8 patients completed 210 monitoring protocols, equal to over 1300 questions, with patients often answering questions daily. Providers and patients

  2. Supporting Goal-Oriented Primary Health Care for Seniors with Complex Care Needs Using Mobile Technology: Evaluation and Implementation of the Health System Performance Research Network, Bridgepoint Electronic Patient Reported Outcome Tool.

    Science.gov (United States)

    Steele Gray, Carolyn; Wodchis, Walter P; Upshur, Ross; Cott, Cheryl; McKinstry, Brian; Mercer, Stewart; Palen, Ted E; Ramsay, Tim; Thavorn, Kednapa

    2016-06-24

    Older adults experiencing multiple chronic illnesses are at high risk of hospitalization and health decline if they are unable to manage the significant challenges posed by their health conditions. Goal-oriented care approaches can provide better care for these complex patients, but clinicians find the process of ascertaining goals "too complex and too-time consuming," and goals are often not agreed upon between complex patients and their providers. The electronic patient reported outcomes (ePRO) mobile app and portal offers an innovative approach to creating and monitoring goal-oriented patient-care plans to improve patient self-management and shared decision-making between patients and health care providers. The ePRO tool also supports proactive patient monitoring by the patient, caregiver(s), and health care provider. It was developed with and for older adults with complex care needs as a means to improve their quality of life. Our proposed project will evaluate the use, effectiveness, and value for money of the ePRO tool in a 12-month multicenter, randomized controlled trial in Ontario; targeting individuals 65 or over with two or more chronic conditions that require frequent health care visits to manage their health conditions. Intervention groups using the ePRO tool will be compared with control groups on measures of quality of life, patient experience, and cost-effectiveness. We will also evaluate the implementation of the tool. The proposed project presented in this paper will be funded through the Canadian Institute for Health Research (CIHR) eHealth Innovation Partnerships Program (eHIPP) program (CIHR-348362). The expected completion date of the study is November, 2019. We anticipate our program of work will support improved quality of life and patient self-management, improved patient-centered primary care delivery, and will encourage the adoption of goal-oriented care approaches across primary health care systems. We have partnered with family health

  3. The Mobile Chamber

    Science.gov (United States)

    Scharfstein, Gregory; Cox, Russell

    2012-01-01

    A document discusses a simulation chamber that represents a shift from the thermal-vacuum chamber stereotype. This innovation, currently in development, combines the capabilities of space simulation chambers, the user-friendliness of modern-day electronics, and the modularity of plug-and-play computing. The Mobile Chamber is a customized test chamber that can be deployed with great ease, and is capable of bringing payloads at temperatures down to 20 K, in high vacuum, and with the desired metrology instruments integrated to the systems control. Flexure plans to lease Mobile Chambers, making them affordable for smaller budgets and available to a larger customer base. A key feature of this design will be an Apple iPad-like user interface that allows someone with minimal training to control the environment inside the chamber, and to simulate the required extreme environments. The feedback of thermal, pressure, and other measurements is delivered in a 3D CAD model of the chamber's payload and support hardware. This GUI will provide the user with a better understanding of the payload than any existing thermal-vacuum system.

  4. Mobile Applications and 4G Wireless Networks: A Framework for Analysis

    Science.gov (United States)

    Yang, Samuel C.

    2012-01-01

    Purpose: The use of mobile wireless data services continues to increase worldwide. New fourth-generation (4G) wireless networks can deliver data rates exceeding 2 Mbps. The purpose of this paper is to develop a framework of 4G mobile applications that utilize such high data rates and run on small form-factor devices. Design/methodology/approach:…

  5. Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6.

    Science.gov (United States)

    Decarli, R; Walter, F; Venemans, B P; Bañados, E; Bertoldi, F; Carilli, C; Fan, X; Farina, E P; Mazzucchelli, C; Riechers, D; Rix, H-W; Strauss, M A; Wang, R; Yang, Y

    2017-05-24

    The existence of massive (1011 solar masses) elliptical galaxies by redshift z ≈ 4 (refs 1, 2, 3; when the Universe was 1.5 billion years old) necessitates the presence of galaxies with star-formation rates exceeding 100 solar masses per year at z > 6 (corresponding to an age of the Universe of less than 1 billion years). Surveys have discovered hundreds of galaxies at these early cosmic epochs, but their star-formation rates are more than an order of magnitude lower. The only known galaxies with very high star-formation rates at z > 6 are, with one exception, the host galaxies of quasars, but these galaxies also host accreting supermassive (more than 109 solar masses) black holes, which probably affect the properties of the galaxies. Here we report observations of an emission line of singly ionized carbon ([C ii] at a wavelength of 158 micrometres) in four galaxies at z > 6 that are companions of quasars, with velocity offsets of less than 600 kilometres per second and linear offsets of less than 100 kiloparsecs. The discovery of these four galaxies was serendipitous; they are close to their companion quasars and appear bright in the far-infrared. On the basis of the [C ii] measurements, we estimate star-formation rates in the companions of more than 100 solar masses per year. These sources are similar to the host galaxies of the quasars in [C ii] brightness, linewidth and implied dynamical mass, but do not show evidence for accreting supermassive black holes. Similar systems have previously been found at lower redshift. We find such close companions in four out of the twenty-five z > 6 quasars surveyed, a fraction that needs to be accounted for in simulations. If they are representative of the bright end of the [C ii] luminosity function, then they can account for the population of massive elliptical galaxies at z ≈ 4 in terms of the density of cosmic space.

  6. Revisiting inland hypoxia: diverse exceedances of dissolved oxygen thresholds for freshwater aquatic life.

    Science.gov (United States)

    Saari, Gavin N; Wang, Zhen; Brooks, Bryan W

    2017-04-11

    Water resources in many regions are stressed by impairments resulting from climate change, population growth and urbanization. In the United States (US), water quality criteria (WQC) and standards (WQS) were established to protect surface waters and associated designated uses, including aquatic life. In inland waters of the south central US, for example, depressed dissolved oxygen (DO) consistently results in impaired aquatic systems due to noncompliance with DO WQC and WQS. In the present study, we systematically examined currently available DO threshold data for freshwater fish and invertebrates and performed probabilistic aquatic hazard assessments with low DO toxicity data that were used to derive the US Environmental Protection Agency's (EPA) Ambient Water Quality Criteria (AWQC) for DO and newly published information. Aquatic hazard assessments predicted acute invertebrate DO thresholds for Ephemeroptera, Plecoptera, or Trichoptera (EPT) taxa and species inhabiting lotic systems to be more sensitive than fish. For example, these organisms were predicted to have acute low DO toxicity thresholds exceeding the US EPA guidelines 17, 26, 31 and 38% and 13, 24, 30 and 39% of the time at 8.0, 5.0, 4.0 and 3.0 mg DO/L, respectively. Based on our analysis, it appears possible that low DO effects to freshwater organisms have been underestimated. We also identified influences of temperature on low DO thresholds and pronounced differences in implementation and assessment of the US EPA AWQC among habitats, seasons, and geographic regions. These results suggest some implemented DO guidelines may adversely affect the survival, growth, and reproduction of freshwater aquatic organisms in a region susceptible to climate change and rapid population growth. Given the global decline of species, particularly invertebrates, low DO threshold information, including sublethal (e.g., reproduction, behavior) responses, for additional species (e.g., mollusks, other invertebrates, warm

  7. Application of at-site peak-streamflow frequency analyses for very low annual exceedance probabilities

    Science.gov (United States)

    Asquith, William H.; Kiang, Julie E.; Cohn, Timothy A.

    2017-07-17

    The U.S. Geological Survey (USGS), in cooperation with the U.S. Nuclear Regulatory Commission, has investigated statistical methods for probabilistic flood hazard assessment to provide guidance on very low annual exceedance probability (AEP) estimation of peak-streamflow frequency and the quantification of corresponding uncertainties using streamgage-specific data. The term “very low AEP” implies exceptionally rare events defined as those having AEPs less than about 0.001 (or 1 × 10–3 in scientific notation or for brevity 10–3). Such low AEPs are of great interest to those involved with peak-streamflow frequency analyses for critical infrastructure, such as nuclear power plants. Flood frequency analyses at streamgages are most commonly based on annual instantaneous peak streamflow data and a probability distribution fit to these data. The fitted distribution provides a means to extrapolate to very low AEPs. Within the United States, the Pearson type III probability distribution, when fit to the base-10 logarithms of streamflow, is widely used, but other distribution choices exist. The USGS-PeakFQ software, implementing the Pearson type III within the Federal agency guidelines of Bulletin 17B (method of moments) and updates to the expected moments algorithm (EMA), was specially adapted for an “Extended Output” user option to provide estimates at selected AEPs from 10–3 to 10–6. Parameter estimation methods, in addition to product moments and EMA, include L-moments, maximum likelihood, and maximum product of spacings (maximum spacing estimation). This study comprehensively investigates multiple distributions and parameter estimation methods for two USGS streamgages (01400500 Raritan River at Manville, New Jersey, and 01638500 Potomac River at Point of Rocks, Maryland). The results of this study specifically involve the four methods for parameter estimation and up to nine probability distributions, including the generalized extreme value, generalized

  8. 75 FR 4343 - Foreign-Trade Zone 22-Chicago, IL; Application for Manufacturing Authority; LG Electronics...

    Science.gov (United States)

    2010-01-27

    ... Electronics MobileComm USA, Inc. (Cell Phone Kitting and Distribution); Bolingbrook, IL An application has..., grantee of FTZ 22, requesting manufacturing authority on behalf of LG Electronics MobileComm USA, Inc...

  9. ELECTRONS IN NONPOLAR LIQUIDS.

    Energy Technology Data Exchange (ETDEWEB)

    HOLROYD,R.A.

    2002-10-22

    Excess electrons can be introduced into liquids by absorption of high energy radiation, by photoionization, or by photoinjection from metal surfaces. The electron's chemical and physical properties can then be measured, but this requires that the electrons remain free. That is, the liquid must be sufficiently free of electron attaching impurities for these studies. The drift mobility as well as other transport properties of the electron are discussed here as well as electron reactions, free-ion yields and energy levels, Ionization processes typically produce electrons with excess kinetic energy. In liquids during thermalization, where this excess energy is lost to bath molecules, the electrons travel some distance from their geminate positive ions. In general the electrons at this point are still within the coulombic field of their geminate ions and a large fraction of the electrons recombine. However, some electrons escape recombination and the yield that escapes to become free electrons and ions is termed G{sub fi}. Reported values of G{sub fi} for molecular liquids range from 0.05 to 1.1 per 100 eV of energy absorbed. The reasons for this 20-fold range of yields are discussed here.

  10. Calculating polaron mobility in halide perovskites

    Science.gov (United States)

    Frost, Jarvist Moore

    2017-11-01

    Lead halide perovskite semiconductors are soft, polar materials. The strong driving force for polaron formation (the dielectric electron-phonon coupling) is balanced by the light band effective masses, leading to a strongly-interacting large polaron. A first-principles prediction of mobility would help understand the fundamental mobility limits. Theories of mobility need to consider the polaron (rather than free-carrier) state due to the strong interactions. In this material we expect that at room temperature polar-optical phonon mode scattering will dominate and so limit mobility. We calculate the temperature-dependent polaron mobility of hybrid halide perovskites by variationally solving the Feynman polaron model with the finite-temperature free energies of Ōsaka. This model considers a simplified effective-mass band structure interacting with a continuum dielectric of characteristic response frequency. We parametrize the model fully from electronic-structure calculations. In methylammonium lead iodide at 300 K we predict electron and hole mobilities of 133 and 94 cm2V-1s-1 , respectively. These are in acceptable agreement with single-crystal measurements, suggesting that the intrinsic limit of the polaron charge carrier state has been reached. Repercussions for hot-electron photoexcited states are discussed. As well as mobility, the model also exposes the dynamic structure of the polaron. This can be used to interpret impedance measurements of the charge-carrier state. We provide the phonon-drag mass renormalization and scattering time constants. These could be used as parameters for larger-scale device models and band-structure dependent mobility simulations.

  11. Mobile Healthcare System using NFC Technology

    OpenAIRE

    A Devendran; T. Bhuvaneswari; Arun Kumar Krishnan

    2012-01-01

    Although primary care physicians are increasingly interested in adopting electronic medical record (EMR) systems, few use such systems in practice. Mobile devices offer new ways for users to access health care data and services in a secure and user-friendly environment. Mobile healthcare (m-healthcare) systems are regarded as a solution to healthcare costs without reducing the quality of patient care. We are developing a basic architecture for m-healthcare services using Near Field Communicat...

  12. Mobile communication in the global south

    DEFF Research Database (Denmark)

    Ling, Richard; Horst, Heather

    2011-01-01

    Mobile communication has become a common phenomenon in most parts of the world. There are indeed more mobile subscriptions than there are people who use the internet. For many people outside of the metropolitan areas of Europe and North America, this is literally their first use of electronically...... mediated interaction. This preface to the special issue of New Media & Society examines mobile communication in a global context. Through an overview of eight articles situated in the global south, we describe how mobile communication sheds light upon notions of information, appropriation and development...... of mobile communication in the global south helps us to understand the rise of innovative practices around information and communication technologies and, in turn, enables us to develop theory to understand these emergent empirical realities....

  13. TYPOLOGIES OF MOBILE APPLICATIONS

    OpenAIRE

    Ion Ivan; Alin Zamfiroiu; Dragoş Palaghiţă3

    2013-01-01

    Mobile applications and their particularities are analyzed. Mobile application specific characteristics are defined. Types of applications are identified and analyzed. The paper established differences between mobile applications and mobile application categories. For each identified type the specific structures and development model are identified.

  14. Exceedance probability map: a tool helping the definition of arsenic Natural Background Level (NBL) within the Drainage Basin to the Venice Lagoon (NE Italy)

    Science.gov (United States)

    Dalla Libera, Nico; Fabbri, Paolo; Mason, Leonardo; Piccinini, Leonardo; Pola, Marco

    2017-04-01

    Arsenic groundwater contamination affects worldwide shallower groundwater bodies. Starting from the actual knowledges around arsenic origin into groundwater, we know that the major part of dissolved arsenic is naturally occurring through the dissolution of As-bearing minerals and ores. Several studies on the shallow aquifers of both the regional Venetian Plain (NE Italy) and the local Drainage Basin to the Venice Lagoon (DBVL) show local high arsenic concentration related to peculiar geochemical conditions, which drive arsenic mobilization. The uncertainty of arsenic spatial distribution makes difficult both the evaluation of the processes involved in arsenic mobilization and the stakeholders' decision about environmental management. Considering the latter aspect, the present study treats the problem of the Natural Background Level (NBL) definition as the threshold discriminating the natural contamination from the anthropogenic pollution. Actually, the UE's Directive 2006/118/EC suggests the procedures and criteria to set up the water quality standards guaranteeing a healthy status and reversing any contamination trends. In addition, the UE's BRIDGE project proposes some criteria, based on the 90th percentile of the contaminant's concentrations dataset, to estimate the NBL. Nevertheless, these methods provides just a statistical NBL for the whole area without considering the spatial variation of the contaminant's concentration. In this sense, we would reinforce the NBL concept using a geostatistical approach, which is able to give some detailed information about the distribution of arsenic concentrations and unveiling zones with high concentrations referred to the Italian drinking water standard (IDWS = 10 µg/liter). Once obtained the spatial information about arsenic distribution, we can apply the 90th percentile methods to estimate some Local NBL referring to every zones with arsenic higher than IDWS. The indicator kriging method was considered because it

  15. Next generation mobile broadcasting

    CERN Document Server

    Gómez-Barquero, David

    2013-01-01

    Next Generation Mobile Broadcasting provides an overview of the past, present, and future of mobile multimedia broadcasting. The first part of the book-Mobile Broadcasting Worldwide-summarizes next-generation mobile broadcasting technologies currently available. This part covers the evolutions of the Japanese mobile broadcasting standard ISDB-T One-Seg, ISDB-Tmm and ISDB-TSB; the evolution of the South Korean T-DMB mobile broadcasting technology AT-DMB; the American mobile broadcasting standard ATSC-M/H; the Chinese broadcasting technologies DTMB and CMMB; second-generation digital terrestrial

  16. Situated learning in the mobile age: mobile devices on a field trip to the sea

    Directory of Open Access Journals (Sweden)

    Vanessa D.I. Pfeiffer

    2009-12-01

    Full Text Available This study focuses on learning about fish biodiversity via mobile devices in a situated learning scenario. Mobile devices do not only facilitate relating the presented information to the real world in a direct way; they also allow the provision of dynamic representations on demand. This study asks whether mobile devices are suited to support knowledge acquisition in a situated learning scenario and whether providing dynamic content is an additional benefit of mobile devices in combination with a real-world experience. The study was conducted during a regular university course at the Mediterranean Sea. Students had to acquire knowledge on 18 Mediterranean fish species by using either static (n = 16 or dynamic learning materials (n = 17. An initial classroom activity was followed by a real-world experience with mobile devices (snorkelling activity. Learning outcomes were measured before and after snorkelling. A 2×2 mixed ANOVA revealed that students performed better after than before the mobile learning experience, whereas no main effect for learning material could be found. However, an interaction between both factors indicated that the knowledge gain in the dynamic group exceeded the knowledge gain in the static group. These results indicate that mobile devices are helpful to unfold the potential of dynamic visualisations for learning biodiversity in a situated learning scenario.

  17. Magnitude of flood flows for selected annual exceedance probabilities for streams in Massachusetts

    Science.gov (United States)

    Zarriello, Phillip J.

    2017-05-11

    The U.S. Geological Survey, in cooperation with the Massachusetts Department of Transportation, determined the magnitude of flood flows at selected annual exceedance prob­abilities (AEPs) at streamgages in Massachusetts and from these data developed equations for estimating flood flows at ungaged locations in the State. Flood magnitudes were deter­mined for the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEPs at 220 streamgages, 125 of which are in Massachusetts and 95 are in the adjacent States of Connecticut, New Hamp­shire, New York, Rhode Island, and Vermont. AEP flood flows were computed for streamgages using the expected moments algorithm weighted with a recently computed regional skew­ness coefficient for New England.Regional regression equations were developed to estimate the magnitude of floods for selected AEP flows at ungaged sites from 199 selected streamgages and for 60 potential explanatory basin characteristics. AEP flows for 21 of the 125 streamgages in Massachusetts were not used in the final regional regression analysis, primarily because of regulation or redundancy. The final regression equations used general­ized least squares methods to account for streamgage record length and correlation. Drainage area, mean basin elevation, and basin storage explained 86 to 93 percent of the variance in flood magnitude from the 50- to 0.2-percent AEPs, respec­tively. The estimates of AEP flows at streamgages can be improved by using a weighted estimate that is based on the magnitude of the flood and associated uncertainty from the at-site analysis and the regional regression equations. Weighting procedures for estimating AEP flows at an ungaged site on a gaged stream also are provided that improve estimates of flood flows at the ungaged site when hydrologic characteristics do not abruptly change.Urbanization expressed as the percentage of imperviousness provided some explanatory power in the regional regression; however, it was not statistically

  18. The Mobile City : The planning and design of the Network City from a mobility point of view

    NARCIS (Netherlands)

    Rooij, R.M.

    2005-01-01

    Cities have changed. People have changed. The 21st century, western citizens of the world travel more often, with more comfort, and longer distances than ever. History shows that a growing economy leads to a growing human need for communication and mobility. The daily action space of people exceeds

  19. Mobile platform security

    CERN Document Server

    Asokan, N; Dmitrienko, Alexandra

    2013-01-01

    Recently, mobile security has garnered considerable interest in both the research community and industry due to the popularity of smartphones. The current smartphone platforms are open systems that allow application development, also for malicious parties. To protect the mobile device, its user, and other mobile ecosystem stakeholders such as network operators, application execution is controlled by a platform security architecture. This book explores how such mobile platform security architectures work. We present a generic model for mobile platform security architectures: the model illustrat

  20. Charging of mobile services by mobile payment reference model

    OpenAIRE

    Pousttchi, Key; Wiedemann, Dietmar Georg

    2005-01-01

    The purpose of the paper is to analyze mobile payments in the mobile commerce scenario. Therefore, we first classify the mobile payment in the mobile commerce scenario by explaining general offer models, charging concepts, and intermediaries. Second, we describe the mobile payment reference model, especially, the mobile payment reference organization model and different mobile payment standard types. Finally, we conclude our findings.