Science.gov

Sample records for affecting device performance

  1. Factors affecting intrauterine contraceptive device performance. I. Endometrial cavity length.

    PubMed

    Hasson, H M; Berger, G S; Edelman, D A

    1976-12-15

    The relationship of endometrial cavity length to intrauterine contraceptive device (IUD) performance was evaluated in 319 patients wearing three types of devices. The rate of events, defined as pregnancy, expulsion, or medical removal, increased significantly when the length of the IUD was equal to, exceeded, or was shorter by two or more centimeters than the length of the endometrial cavity. Total uterine length was found to be a less accurate prognostic indicator of IUD performance than endometrial cavity length alone. PMID:998687

  2. Device Performance

    SciTech Connect

    Not Available

    2006-06-01

    In the Device Performance group, within the National Center for Photovoltaic's Measurements and Characterization Division, we measure the performance of PV cells and modules with respect to standard reporting conditions--defined as a reference temperature (25 C), total irradiance (1000 Wm-2), and spectral irradiance distribution (IEC standard 60904-3). Typically, these are ''global'' reference conditions, but we can measure with respect to any reference set. To determine device performance, we conduct two general categories of measurements: spectral responsivity (SR) and current versus voltage (I-V). We usually perform these measurements using standard procedures, but we develop new procedures when required by new technologies. We also serve as an independent facility for verifying device performance for the entire PV community. We help the PV community solve its special measurement problems, giving advice on solar simulation, instrumentation for I-V measurements, reference cells, measurement procedures, and anomalous results. And we collaborate with researchers to analyze devices and materials.

  3. Investigation of factors affecting terrestrial passive sampling device performance and uptake rates in laboratory chambers

    SciTech Connect

    Johnson, K.A.; Weisskopf, C.P.

    1995-12-31

    A rapid sampling method using passive sampling devices (PSDS) for soil contaminant characterization shows extreme promise. The use of PSDs increases ease and speed of analysis, decreases solvent usage and cost, and minimizes the transport of contaminated soils. Time and cost savings allow a high sampling frequency, providing a more thorough site characterization than traditional methods. The authors have conducted both laboratory and field studies with terrestrial PSDS. Laboratory studies demonstrated the concentration and moisture dependence of sampler uptake and provided an estimate of the optimal field sampling time for soils contaminated with polychlorinated biphenyls (PCBs). These PSDs were also used to accurately estimate PCB concentrations at hazardous waste site where concentrations ranged from 0.01 to 200 ug PCB/g soil. However, PSDs in the field had sampling rates approximately three times greater than in the laboratory. As a result several factors affecting PSD sampling rates and/or performance in laboratory chambers were evaluated. The parameters investigated were soil bulk density or compactness, chamber size and air flow. The chemicals used in these studies included two PCB congeners (52 and 153), three organochlorine pesticides (DDT, dieldrin and methoxychlor), three organophosphate pesticides (chlorpyrifos, diazinon and terbufos) and three herbicides (alachlor, atrazine and metolachlor).

  4. Performance of low-light-level night vision device affected by backscattered electron from ion barrier film

    NASA Astrophysics Data System (ADS)

    Yan, Lei; Shi, Feng; Cheng, Yaojin; Hou, Zhipeng; Shi, Hongli; Zhu, Wanping; Liu, Beibei; Zhang, Ni

    2012-10-01

    In order to suggest the performance of low-light-level night vision device affected by backscattered electron from ion barrier film(IBF), in this paper, based on the idea of Monte-Carlo, the track of electron impinging and rebounding on ion barrier film is simulated. The Lambert distribution and Beta distribution are used to calculate electron's emission. The Mott cross section and the Bethe formula rewrited by Joy are used to describe and calculate the elastic and inelastic scattering electron traversing in the film. With the statistic of the total transmitted electron and the discussion on the effect of cathode voltage, proximity between ion barrier film and photocathode on performance of low-light-level night vision device, we get the point diffusion function of ion barrier film, and we conclude that in low light level backscattered electron hardly affect working of image intensifier and higher cathode voltage, closer proximity between cathode and ion film will reduce the impact of backscattered electron in high light level.

  5. The use of a displacement device negatively affects the performance of dogs (Canis familiaris) in visible object displacement tasks

    PubMed Central

    Müller, Corsin A.; Riemer, Stefanie; Range, Friederike; Huber, Ludwig

    2014-01-01

    Visible and invisible displacement tasks have been used widely for comparative studies of animals’ understanding of object permanence, with evidence accumulating that some species can solve invisible displacement tasks and thus reach Piagetian stage 6 of object permanence. In contrast, dogs appear to rely on associative cues, such as the location of the displacement device, during invisible displacement tasks. It remains unclear, however, whether dogs, and other species that failed in invisible displacement tasks, do so due to their inability to form a mental representation of the target object, or simply due to the involvement of a more salient but potentially misleading associative cue, the displacement device. Here we show that the use of a displacement device impairs the performance of dogs also in visible displacement tasks: their search accuracy was significantly lower when a visible displacement was performed with a displacement device, and only two of initially 42 dogs passed the sham-baiting control conditions. The negative influence of the displacement device in visible displacement tasks may be explained by strong associative cues overriding explicit information about the target object’s location, reminiscent of an overshadowing effect, and/or object individuation errors as the target object is placed within the displacement device and moves along a spatiotemporally identical trajectory. Our data suggest that a comprehensive appraisal of a species’ performance in object permanence tasks should include visible displacement tasks with the same displacement device used in invisible displacements, which typically has not been done in the past. PMID:24611641

  6. Human performance measuring device

    NASA Technical Reports Server (NTRS)

    Michael, J.; Scow, J.

    1970-01-01

    Complex coordinator, consisting of operator control console, recorder, subject display panel, and limb controls, measures human performance by testing perceptual and motor skills. Device measures psychophysiological functions in drug and environmental studies, and is applicable to early detection of psychophysiological body changes.

  7. Defects and device performance

    NASA Technical Reports Server (NTRS)

    Storti, G.; Armstrong, R.; Johnson, S.; Lin, H. C.; Regnault, W.; Yoo, K. C.

    1985-01-01

    The necessity for a low-cost crystalline silicon sheet material for photovoltaics has generated a number of alternative crystal growth techniques that would replace Czochralski (Cz) and float-zone (FZ) technologies. Efficiencies of devices fabricated from low resistivity FZ silicon are approaching 20%, and it is highly likely that this value will be superseded in the near future. However, FZ silicon is expensive, and is unlikely ever to be used for photovoltaics. Cz silicon has many of the desirable qualities of FZ except that minority-carrier lifetimes at lower resistivities are significantly less than those of FZ silicon. Even with Cz silicon, it is unlikely that cost goals can be met because of the poor-material yield that results from sawing and other aspects of the crystal rowth. Although other silicon sheet technologies have been investigated, almost all have characteristics that limit efficiency to approx. 16%. In summary, 20% efficient solar cells can likely be fabricated from both FZ and Cz silicon, but costs are likely to be ultimately unacceptable. Alternate silicon technologies are not likely to achieve this goal, but cost per watt figures may be eventually better than either of the single crystal technologies and may rival any thin-film technology.

  8. Quantum Tunneling Affects Engine Performance.

    PubMed

    Som, Sibendu; Liu, Wei; Zhou, Dingyu D Y; Magnotti, Gina M; Sivaramakrishnan, Raghu; Longman, Douglas E; Skodje, Rex T; Davis, Michael J

    2013-06-20

    We study the role of individual reaction rates on engine performance, with an emphasis on the contribution of quantum tunneling. It is demonstrated that the effect of quantum tunneling corrections for the reaction HO2 + HO2 = H2O2 + O2 can have a noticeable impact on the performance of a high-fidelity model of a compression-ignition (e.g., diesel) engine, and that an accurate prediction of ignition delay time for the engine model requires an accurate estimation of the tunneling correction for this reaction. The three-dimensional model includes detailed descriptions of the chemistry of a surrogate for a biodiesel fuel, as well as all the features of the engine, such as the liquid fuel spray and turbulence. This study is part of a larger investigation of how the features of the dynamics and potential energy surfaces of key reactions, as well as their reaction rate uncertainties, affect engine performance, and results in these directions are also presented here. PMID:26283246

  9. High performance thermoelectric nanocomposite device

    DOEpatents

    Yang, Jihui; Snyder, Dexter D.

    2011-10-25

    A thermoelectric device includes a nanocomposite material with nanowires of at least one thermoelectric material having a predetermined figure of merit, the nanowires being formed in a porous substrate having a low thermal conductivity and having an average pore diameter ranging from about 4 nm to about 300 nm.

  10. Performance of a constant torque pedal device.

    PubMed Central

    Sherwin, K.

    1979-01-01

    A constant-torque oscillatory pedal-crank device using vertical movement of the feet is described and its performance compared to a conventional rotational cycle. Using a generator to measure the power output the constant-torque device produced 33% less power and thus has no practical value as an alternative to the conventional pedal-crank system. Images Figure 3 PMID:526783

  11. Performance of Installed Cooking Exhaust Devices

    SciTech Connect

    Singer, Brett C.; Delp, William W.; Apte, Michael G.; Price, Philip N.

    2011-11-01

    The performance metrics of airflow, sound, and combustion product capture efficiency (CE) were measured for a convenience sample of fifteen cooking exhaust devices, as installed in residences. Results were analyzed to quantify the impact of various device- and installation-dependent parameters on CE. Measured maximum airflows were 70% or lower than values noted on product literature for 10 of the devices. Above-the-cooktop devices with flat bottom surfaces (no capture hood) – including exhaust fan/microwave combination appliances – were found to have much lower CE at similar flow rates, compared to devices with capture hoods. For almost all exhaust devices and especially for rear-mounted downdraft exhaust and microwaves, CE was substantially higher for back compared with front burner use. Flow rate, and the extent to which the exhaust device extends over the burners that are in use, also had a large effect on CE. A flow rate of 95 liters per second (200 cubic feet per minute) was necessary, but not sufficient, to attain capture efficiency in excess of 75% for the front burners. A-weighted sound levels in kitchens exceeded 57 dB when operating at the highest fan setting for all 14 devices evaluated for sound performance.

  12. High performance bio-integrated devices

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Hyeong; Lee, Jongha; Park, Minjoon

    2014-06-01

    In recent years, personalized electronics for medical applications, particularly, have attracted much attention with the rise of smartphones because the coupling of such devices and smartphones enables the continuous health-monitoring in patients' daily life. Especially, it is expected that the high performance biomedical electronics integrated with the human body can open new opportunities in the ubiquitous healthcare. However, the mechanical and geometrical constraints inherent in all standard forms of high performance rigid wafer-based electronics raise unique integration challenges with biotic entities. Here, we describe materials and design constructs for high performance skin-mountable bio-integrated electronic devices, which incorporate arrays of single crystalline inorganic nanomembranes. The resulting electronic devices include flexible and stretchable electrophysiology electrodes and sensors coupled with active electronic components. These advances in bio-integrated systems create new directions in the personalized health monitoring and/or human-machine interfaces.

  13. How Coriolis meter design affects field performance

    SciTech Connect

    Levien, A.; Dudiak, A.

    1995-12-31

    Although many possibilities exist for the design of Coriolis flowmeters, a common set of fundamental physical principles affect practical meter design. Design criteria such as tube geometry, alloy section, operating frequencies, stress levels, and tubing wall thickness have varying impacts on meter performance. Additionally, field conditions such as changing temperature, pressure, pipeline stress and vibration affect measurement performance. The challenge created in Coriolis flow meter design is to maximize the sensitivity of the meter Coriolis forces, while minimizing the impact of outside environmental influences. Data are presented on the physical principles that affect Coriolis flowmeters, and how the various aspects of meter design influence field performance.

  14. Pointing Device Performance in Steering Tasks.

    PubMed

    Senanayake, Ransalu; Goonetilleke, Ravindra S

    2016-06-01

    Use of touch-screen-based interactions is growing rapidly. Hence, knowing the maneuvering efficacy of touch screens relative to other pointing devices is of great importance in the context of graphical user interfaces. Movement time, accuracy, and user preferences of four pointing device settings were evaluated on a computer with 14 participants aged 20.1 ± 3.13 years. It was found that, depending on the difficulty of the task, the optimal settings differ for ballistic and visual control tasks. With a touch screen, resting the arm increased movement time for steering tasks. When both performance and comfort are considered, whether to use a mouse or a touch screen for person-computer interaction depends on the steering difficulty. Hence, a input device should be chosen based on the application, and should be optimized to match the graphical user interface. PMID:27216944

  15. Outcomes in cochlear implantation: variables affecting performance in adults and children.

    PubMed

    Cosetti, Maura K; Waltzman, Susan B

    2012-02-01

    This article highlights variables that affect cochlear implant performance, emerging factors warranting consideration, and variables shown not to affect performance. Research on the outcomes following cochlear implantation has identified a wide spectrum of variables known to affect pos0timplantation performance. These variables relate to the device itself as well as individual patient characteristics. Factors believed to affect spiral ganglion cell survival and function have been shown to influence postoperative performance. Binaural hearing affects performance. Social and educational factors also affect postoperative performance. Novel variables capable of affecting performance continue to emerge with increased understanding of auditory pathway development and neural plasticity. PMID:22115688

  16. High performance flexible electronics for biomedical devices.

    PubMed

    Salvatore, Giovanni A; Munzenrieder, Niko; Zysset, Christoph; Kinkeldei, Thomas; Petti, Luisa; Troster, Gerhard

    2014-01-01

    Plastic electronics is soft, deformable and lightweight and it is suitable for the realization of devices which can form an intimate interface with the body, be implanted or integrated into textile for wearable and biomedical applications. Here, we present flexible electronics based on amorphous oxide semiconductors (a-IGZO) whose performance can achieve MHz frequency even when bent around hair. We developed an assembly technique to integrate complex electronic functionalities into textile while preserving the softness of the garment. All this and further developments can open up new opportunities in health monitoring, biotechnology and telemedicine. PMID:25570912

  17. Microscale Confinement features in microfluidic devices can affect biofilm

    SciTech Connect

    Kumar, Aloke; Karig, David K; Neethirajan, Suresh; Acharya, Rajesh K; Mukherjee, Partha P; Retterer, Scott T; Doktycz, Mitchel John

    2013-01-01

    Biofilms are aggregations of microbes that are encased by extra-cellular polymeric substances (EPS) and adhere to surfaces and interfaces. Biofilm development on abiotic surfaces is a dynamic process, which typically proceeds through an initial phase of adhesion of plankntonic microbes to the substrate, followed by events such as growth, maturation and EPS secretion. However, the coupling of hydrodynamics, microbial adhesion and biofilm growth remain poorly understood. Here, we investigate the effect of semiconfined features on biofilm formation. Using a microfluidic device and fluorescent time-lapse microscopy, we establish that confinement features can significantly affect biofilm formation. Biofilm dynamics change not only as a function of confinement features, but also of the total fluid flow rate, and our combination of experimental results and numerical simulations reveal insights into the link between hydrodynamics and biofilm formation.

  18. High-performance parallel input device

    NASA Astrophysics Data System (ADS)

    Daniel, R. W.; Fischer, Patrick J.; Hunter, B.

    1993-12-01

    Research into force reflecting remote manipulation has recently started to move away from common error systems towards explicit force control. In order to maximize the benefit provided by explicit force reflection the designer has to take into account the asymmetry of the bandwidths of the forward and reflecting loops. This paper reports on a high performance system designed and built at Oxford University and Harwell Laboratories and on the preliminary results achieved when performing simple force reflecting tasks. The input device is based on a modified Stewart Platform, which offers the potential of very high bandwidth force reflection, well above the normal 2 - 10 Hz range achieved with common error systems. The slave is a nuclear hardened Puma industrial robot, offering a low cost, reliable solution to remote manipulation tasks.

  19. Factors affecting performance of dispenser photocathodes

    NASA Astrophysics Data System (ADS)

    Moody, Nathan A.; Jensen, Kevin L.; Feldman, Donald W.; Montgomery, Eric J.; O'Shea, Patrick G.

    2007-11-01

    Usable lifetime has long been a limitation of high efficiency photocathodes in high average current accelerator applications such as free electron lasers, where poor vacuum conditions and high incident laser power contribute to early degradation in electron beam emission. Recent progress has been made in adapting well known thermionic dispenser techniques to photocathodes, resulting in a dispenser photocathode whose photosensitive surface coating of cesium can be periodically replenished to extend effective lifetime. This article details the design and fabrication process of a prototype cesium dispenser photocathode and describes in detail the dominant factors affecting its performance: activation procedure, surface cleanliness, temperature, and substrate microstructure.

  20. Exciton dynamics and device performance in polythiophene heterojunctions for photovoltaics

    NASA Astrophysics Data System (ADS)

    Chasteen, Stephanie V.; Carter, Sue A.; Rumbles, Garry

    2005-10-01

    We present time-resolved photoluminescence studies in conjunction with device characterization of a variety of heterojunctions with poly-(3-hexylthiophene), or P3HT, as a means to understand how exciton dynamics affect device performance. We find that blends of P3HT with the electron-transporting polymer CN-ether-PPV and with the fullerene derivative PCBM result in ~4-fold and ~15-fold improvements in short-circuit currents, respectively, over neat-film P3HT on TiO2 solgel. Despite efficient charge-transfer in P3HT:PCBM films, as evidenced by enhanced device performance and quenched steady-state luminescence, we observe only moderate reduction of the excited state lifetime, due to the already efficient non-radiative pathways in P3HT. We observe evidence for a new state that we assign to an exciplex in blends of P3HT with the electron-transporting polymer CN-ether-PPV. The exciplex state, which confirms the existence of charge-transfer between the two polymers, may account for the enhanced device performance of these blends by acting as a scavenger for excitons that would otherwise decay rapidly via non-radiative pathways. The long-range order of P3HT is disrupted when spin-cast on rough TiO2 nanoparticles, and this results in a blueshift of the PL spectrum and a new long-lived decay component that we attribute to long-lived intrachain polarons. P3HT on smooth TiO2 solgel films shows little or no quenching of the excited state, despite known charge transfer from P3HT to TiO2.

  1. On performing semantic queries in small devices

    NASA Astrophysics Data System (ADS)

    Costea, C.; Petrovan, A.; Neamţ, L.; Chiver, O.

    2016-08-01

    The sensors have a well-defined role in control or monitoring industrial processes; the data given by them can generate valuable information of the trend of the systems to which they belong, but to store a large volume of data and then analysis offline is not always practical. One solution is on-line analysis, preferably as close to the place where data have been generated (edge computing). An increasing amount of data generated by a growing number of devices connected to the Internet resulted in processing data sensors to the edge of the network, in a middle layer where smart entities should interoperate. Diversity of communication technologies outlined the idea of using intermediate devices such as gateways in sensor networks and for this reason the paper examines the functionality of a SPARQL endpoint in the Raspberry Pi device.

  2. Microfabricated devices for performing chemical and biochemical analysis

    SciTech Connect

    Ramsey, J.M.; Jacobson, S.C.; Foote, R.S.

    1997-05-01

    There is growing interest in microfabricated devices that perform chemical and biochemical analysis. The general goal is to use microfabrication tools to construct miniature devices that can perform a complete analysis starting with an unprocessed sample. Such devices have been referred to as lab-on-a-chip devices. Initial efforts on microfluidic laboratory-on-a-chip devices focused on chemical separations. There are many potential applications of these fluidic microchip devices. Some applications such as chemical process control or environmental monitoring would require that a chip be used over an extended period of time or for many analyses. Other applications such as forensics, clinical diagnostics, and genetic diagnostics would employ the chip devices as single use disposable devices.

  3. How Mobile Devices Affect Students According to Teachers' Beliefs

    ERIC Educational Resources Information Center

    Cumaoglu, Gonca Kizilkaya

    2015-01-01

    The purpose of this study is to examine teachers' beliefs concerning the effects on students using mobile devices, and to determine whether these beliefs vary according to the demographic characteristics and Internet usage purposes. For this purpose, a demographic information questionnaire and the scale developed by Diker Coskun & Kizilkaya…

  4. Living with Smartphones: Does Completion Device Affect Survey Responses?

    ERIC Educational Resources Information Center

    Lambert, Amber D.; Miller, Angie L.

    2015-01-01

    With the growing reliance on tablets and smartphones for internet access, understanding the effects of completion device on online survey responses becomes increasing important. This study uses data from the Strategic National Arts Alumni Project, a multi-institution online alumni survey designed to obtain knowledge of arts education, to explore…

  5. PERFORMANCE EVALUATION OF TYPE I MARINE SANITATION DEVICES

    EPA Science Inventory

    This performance test was designed to evaluate the effectiveness of two Type I Marine Sanitation Devices (MSDs): the Electro Scan Model EST 12, manufactured by Raritan Engineering Company, Inc., and the Thermopure-2, manufactured by Gross Mechanical Laboratories, Inc. Performance...

  6. Does Motivation Affect Performance via Persistence?

    ERIC Educational Resources Information Center

    Vollmeyer, Regina; Rheinberg, Falko

    2000-01-01

    Studied the relationships among motivation, persistence, and performance in a sample of 51 German college students. Path analysis showed that initial motivation influenced persistence but that the relationship between persistence and performance was disrupted because learners with more knowledge stopped sooner. (SLD)

  7. Performance evaluation of cellular phone network based portable ECG device.

    PubMed

    Hong, Joo-Hyun; Cha, Eun-Jong; Lee, Tae-Soo

    2008-01-01

    In this study, cellular phone network based portable ECG device was developed and three experiments were performed to evaluate the accuracy, reliability and operability, applicability during daily life of the developed device. First, ECG signals were measured using the developed device and Biopac device (reference device) during sitting and marking time and compared to verify the accuracy of R-R intervals. Second, the reliable data transmission to remote server was verified on two types of simulated emergency event using patient simulator. Third, during daily life with five types of motion, accuracy of data transmission to remote server was verified on two types of event occurring. By acquiring and comparing subject's biomedical signal and motion signal, the accuracy, reliability and operability, applicability during daily life of the developed device were verified. Therefore, cellular phone network based portable ECG device can monitor patient with inobtrusive manner. PMID:19162767

  8. Innovative approaches to improve bulk heterojunction organic photovoltaic device performance

    NASA Astrophysics Data System (ADS)

    Zhang, Ye

    In this thesis we studied the electrical properties of bulk heterojunction organic photovoltaic (OPV) devices fabricated using a variety of conjugated polymers, including regioregular P3HT, regiorandom P3HT, MEH-PPV and Mercedes, and several fullerene derivatives including [C61]PCBM, [C71]PCBM, bis-PCBM, Jalapeno and Habanero. We first optimized the fabrication recipe for P3HT/PCBM devices to yield a power conversion efficiency ˜3.5%, which is comparable to the reported state-of-the-art P3HT/PCBM device performance. We then fabricated OPV devices using alternative high LUMO fullerenes and a narrow bandgap/deep HOMO polymer to enhance OPV device performance and studied the electrical properties of these devices. Devices fabricated using P3HT/Jalapeno demonstrate a high efficiency ˜5%. Finally, we discovered an innovative spin-related method, which can potentially compliment the use of alternative donor/acceptor materials, to enhance OPV device performance. We doped the spin ½ radial Galvinoxyl into P3HT/PCBM devices and improved efficiency from 3.5% to 4%. Our experimental results suggest that the existence of Galvinoxyl at the P3HT/PCBM interface facilitates the exciton/polaron dissociation process, while Galvinoxyl molecules that are sparsely distributed in PCBM domains yield enhanced free charge carrier transport.

  9. Student Profiles and Factors Affecting Performance.

    ERIC Educational Resources Information Center

    Chansarkar, B. A.; Michaeloudis, A.

    2001-01-01

    Studies the profiling of first year students studying the Quantitative Methods for Business module at a British university, and makes policy recommendations to improve student performance. Indicates that the highest proportion of students are United Kingdom students, 58% of the students are male, and only 30% of the students are mature students.…

  10. Factors affecting performance of engineered barriers

    SciTech Connect

    Blink, J. A., LLNL

    1998-03-01

    For the Yucca Mountain Viability Assessment (VA), a reference design was tentatively selected` In September 1997, and a series of model abstractions are being prepared for the performance assessment (PA) of that design. To determine the sensitivity of peak dose rate at the accessible environment to engineered components, several design options were subjected to the PA models available late in FY97.

  11. FACTORS AFFECTING PERFORMANCE OF ENGINEERED BARRIERS

    SciTech Connect

    Blink, J. A.; Bailey, T. W.; Doering, W.; Lee, J. K.; Mccoy, J. K.; McKenzie, D. G.; Sevougian, D.; Vallikat, V.

    1998-03-01

    For the Yucca Mountain Viability Assessment (VA), a reference design was tentatively selected in September 1997, and a series of model abstractions are being prepared for the performance assessment (PA) of that design. To determine the sensitivity of peak dose rate at the accessible environment to engineered components, several design options were subjected to the PA models available late in FY97.

  12. Analysis of Polygonal Distance Protection Relay of Transmission Line Affected by SMES Device

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Zhang, Wenjia

    Because of unique advantages in rapid response and independent control of act ve and reactive power, Superconducting Magnetic Energy Storage (SMES) device will be widely used in the power system. The SMES exchanges power with power grid in the charging and discharging process, so it may affect the performance of protection relay of transmission line, which will lead to mal-operation. Based on SMES model, the tripping characteristic of polygonal distance relay for single-machine-infinite-bus performance of polygonal distance relay with SMES. The simulation results show the measured impedance of polygonal distance relay is changed by SMES, and polygonal distance relay will make mal-operation when faults occur in the boundary of protection zone. Also an improving distance relay is proposed to solve the problem.

  13. Performance Gains of Propellant Management Devices for Liquid Hydrogen Depots

    NASA Technical Reports Server (NTRS)

    Hartwig, Jason W.; McQuillen, John B.; Chato, David J.

    2013-01-01

    This paper presents background, experimental design, and preliminary experimental results for the liquid hydrogen bubble point tests conducted at the Cryogenic Components Cell 7 facility at the NASA Glenn Research Center in Cleveland, Ohio. The purpose of the test series was to investigate the parameters that affect liquid acquisition device (LAD) performance in a liquid hydrogen (LH2) propellant tank, to mitigate risk in the final design of the LAD for the Cryogenic Propellant Storage and Transfer Technology Demonstration Mission, and to provide insight into optimal LAD operation for future LH2 depots. Preliminary test results show an increase in performance and screen retention over the low reference LH2 bubble point value for a 325 2300 screen in three separate ways, thus improving fundamental LH2 LAD performance. By using a finer mesh screen, operating at a colder liquid temperature, and pressurizing with a noncondensible pressurant gas, a significant increase in margin is achieved in bubble point pressure for LH2 screen channel LADs.

  14. Testing Devices Garner Data on Insulation Performance

    NASA Technical Reports Server (NTRS)

    2014-01-01

    To develop a test instrument that could garner measurements of the thermal performance of insulation under extreme conditions, researchers at Kennedy Space Center devised the Cryostat 1 and then Cryostat 2. McLean, Virginia-based QinetiQ North America licensed the technology and plans to market it to organizations developing materials for things like piping and storage tank insulation, refrigeration, appliances, and consumer goods.

  15. Locomotion Performance of Biomimetic Fish-like Swimming Devices

    NASA Astrophysics Data System (ADS)

    Epps, Brenden P.; Valdivia Y Alvarado, Pablo; Techet, Alexandra H.

    2007-11-01

    The swimming performance of a biomimetic, fish-like swimming device, designed to exploit the natural dynamics of its compliant body to achieve locomotion, is studied experimentally. A theoretical model combines beam-bending stress analysis and unsteady hydrodynamic forcing with known material properties of the robot to reveal desired geometry distributions and actuation modes. Swimming kinematics and corresponding performance of the device are also predicted and tested for a carangiform prototype device in a quiescent tank of water. Experimental swimming tests show good agreement with the simplified theoretical models. The hydrodynamic characteristics of the wake behind the device are investigated using time-resolved particle imaging velocimetry (PIV) over a range of tail beat frequencies, from 1 to 4 Hz, to asses vortical wake patterns and hydrodynamic forces. PIV data are compared to theoretical model predictions. Reynolds numbers for the swimming device are between 2500 and 8500 based on body length.

  16. Peri-operative warming devices: performance and clinical application.

    PubMed

    John, M; Ford, J; Harper, M

    2014-06-01

    Since the adverse consequences of accidental peri-operative hypothermia have been recognised, there has been a rapid expansion in the development of new warming equipment designed to prevent it. This is a review of peri-operative warming devices and a critique of the evidence assessing their performance. Forced-air warming is a common and extensively tested warming modality that outperforms passive insulation and water mattresses, and is at least as effective as resistive heating. More recently developed devices include circulating water garments, which have shown promising results due to their ability to cover large surface areas, and negative pressure devices aimed at improving subcutaneous perfusion for warming. We also discuss the challenge of fluid warming, looking particularly at how devices' performance varies according to flow rate. Our ultimate aim is to provide a guide through the bewildering array of devices on the market so that clinicians can make informed and accurate choices for their particular hospital environment. PMID:24720346

  17. New high performance Si for optical devices

    NASA Astrophysics Data System (ADS)

    Tenma, T.; Matsuzaka, M.; Sako, R.; Takase, K.; Chiba, K.

    2016-05-01

    Against the backdrop of a growing demand in the areas of smart buildings, security, vehicle installation, and other applications, the market for far infrared cameras is expected to grow significantly in the future. However, since germanium (Ge) and chalcogenide glass, which have been used as the lens materials of far infrared cameras, are very expensive or highly toxic, there are some problems supporting the growing demand. We have therefore focused attention on silicon, which is inexpensive and less toxic. Although silicon has been used as a lens material of far infrared cameras, there are some problems remaining to be solved: Cz silicon is inexpensive but delivers low transmittance, and Fz silicon delivers sufficient transmittance but is expensive. We have developed New Cz silicon, which delivers high transmittance as Fz silicon does, and is inexpensive as conventional Cz silicon is. We have already started its sample work at both companies in Japan and overseas and have obtained excellent performance results. Mass production is scheduled to start in this fiscal year.

  18. Endogenous Progesterone Concentrations Affect Progesterone Release from Intravaginal Devices Used for Oestrous Synchronization in Cattle.

    PubMed

    Neri, H L; Palhao, M P; Costa, D S; Viana, Jhm; Fernandes, Cac

    2015-08-01

    Intravaginal progesterone-releasing devices are largely used both as contraceptives in humans and as a component of oestrous synchronization protocols in cattle. To reduce costs in large-scale timed artificial insemination, the reuse of these releasing devices is common. Passive hormone diffusion, however, depends on the concentration gradient, which could affect the amount of residual progesterone present in these devices after a first use. To evaluate the effect of the presence of a corpus luteum in the release of progesterone from intravaginal devices, three synchronization protocols were designed to simulate the effects of inserting the device in the early dioestrus, late dioestrus or anoestrus. Holstein-Zebu cross-bred heifers were randomly allocated into one of these three treatments, and a series of blood samples was taken to evaluate the plasma progesterone concentrations. After 8 days, the intravaginal devices were removed and underwent a previously validated alcoholic extraction technique to measure the residual progesterone. Non-used devices were used as controls. As expected, the simultaneous presence of the intravaginal device and a corpus luteum resulted in increased plasma progesterone concentrations. Conversely, the amount of residual progesterone in the devices after use was inversely proportional to the plasma progesterone concentration. These results demonstrate that the release rate of progesterone from intravaginal devices is affected by the endogenous concentration of this hormone; consequently, the strategy for reuse should account for the category and expected luteal cyclic activity of the animals undergoing synchronization protocols. PMID:26059020

  19. Infants' Understanding of Actions Performed by Mechanical Devices

    ERIC Educational Resources Information Center

    Boyer, Ty W.; Pan, J. Samantha; Bertenthal, Bennett I.

    2011-01-01

    Recent research suggests that 9-month-old infants tested in a modified version of the A-not-B search task covertly imitate actions performed by the experimenter. The current study examines whether infants also simulate actions performed by mechanical devices, and whether this varies with whether or not they have been familiarized with the devices…

  20. Performance of a capillary propellant management device with hydrazine

    NASA Technical Reports Server (NTRS)

    Tegart, J. R.

    1979-01-01

    The propellant management device that was successfully used in the Viking Orbiter spacecraft was selected for the main propulsion system of the Teleoperator Retrieval System (TRS). Due to differences in the missions and different propellants, the operation of this sheet metal vane device required reverification for the TRS application. An analytical investigation was performed considering the adverse acceleration environment and the high contract angle of the hydrazine propellant. Drop tower tests demonstrated that the device would provide propellant acquisition while the TRS was docked with Skylab, but its operation would have to be supplemented through propellant settling when free-flying.

  1. Silicon Carbide Diodes Performance Characterization and Comparison With Silicon Devices

    NASA Technical Reports Server (NTRS)

    Lebron-Velilla, Ramon C.; Schwarze, Gene E.; Trapp, Scott

    2003-01-01

    Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers were electrically tested and characterized at room temperature. Performed electrical tests include steady state forward and reverse I-V curves, as well as switching transient tests performed with the diodes operating in a hard switch dc-to-dc buck converter. The same tests were performed in current state of the art silicon (Si) and gallium arsenide (GaAs) Schottky and pn junction devices for evaluation and comparison purposes. The SiC devices tested have a voltage rating of 200, 300, and 600 V. The comparison parameters are forward voltage drop at rated current, reverse current at rated voltage and peak reverse recovery currents in the dc to dc converter. Test results show that steady state characteristics of the tested SiC devices are not superior to the best available Si Schottky and ultra fast pn junction devices. Transient tests reveal that the tested SiC Schottky devices exhibit superior transient behavior. This is more evident at the 300 and 600 V rating where SiC Schottky devices showed drastically lower reverse recovery currents than Si ultra fast pn diodes of similar rating.

  2. Digital Devices, Distraction, and Student Performance: Does In-Class Cell Phone Use Reduce Learning?

    ERIC Educational Resources Information Center

    Duncan, Douglas K.; Hoekstra, Angel R.; Wilcox, Bethany R.

    2012-01-01

    The recent increase in use of digital devices such as laptop computers, iPads, and web-enabled cell phones has generated concern about how technologies affect student performance. Combining observation, survey, and interview data, this research assesses the effects of technology use on student attitudes and learning. Data were gathered in eight…

  3. High voltage stability performance of a gamma ray detection device

    SciTech Connect

    Abdullah, Nor Arymaswati; Lombigit, Lojius; Rahman, Nur Aira Abd

    2014-02-12

    An industrial grade digital radiation survey meter device is currently being developed at Malaysian Nuclear Agency. This device used a cylindrical type Geiger Mueller (GM) which acts as a detector. GM detector operates at relatively high direct current voltages depend on the type of GM tube. This thin/thick walled cylindrical type of GM tube operates at 450-650 volts range. Proper value and stability performance of high voltage are important parameters to ensure that this device give a reliable radiation dose measurement. This paper will present an assessment of the stability and performance of the high voltage supply for radiation detector. The assessment is performed using System Identification tools box in MATLAB and mathematical statistics.

  4. Performance processes within affect-related performance zones: a multi-modal investigation of golf performance.

    PubMed

    van der Lei, Harry; Tenenbaum, Gershon

    2012-12-01

    Individual affect-related performance zones (IAPZs) method utilizing Kamata et al. (J Sport Exerc Psychol 24:189-208, 2002) probabilistic model of determining the individual zone of optimal functioning was utilized as idiosyncratic affective patterns during golf performance. To do so, three male golfers of a varsity golf team were observed during three rounds of golf competition. The investigation implemented a multi-modal assessment approach in which the probabilistic relationship between affective states and both, performance process and performance outcome, measures were determined. More specifically, introspective (i.e., verbal reports) and objective (heart rate and respiration rate) measures of arousal were incorporated to examine the relationships between arousal states and both, process components (i.e., routine consistency, timing), and outcome scores related to golf performance. Results revealed distinguishable and idiosyncratic IAPZs associated with physiological and introspective measures for each golfer. The associations between the IAPZs and decision-making or swing/stroke execution were strong and unique for each golfer. Results are elaborated using cognitive and affect-related concepts, and applications for practitioners are provided. PMID:22562463

  5. Scaling of Performance in Liquid Propellant Rocket Engine Combustion Devices

    NASA Technical Reports Server (NTRS)

    Hulka, James R.

    2008-01-01

    This paper discusses scaling of combustion and combustion performance in liquid propellant rocket engine combustion devices. In development of new combustors, comparisons are often made between predicted performance in a new combustor and measured performance in another combustor with different geometric and thermodynamic characteristics. Without careful interpretation of some key features, the comparison can be misinterpreted and erroneous information used in the design of the new device. This paper provides a review of this performance comparison, including a brief review of the initial liquid rocket scaling research conducted during the 1950s and 1960s, a review of the typical performance losses encountered and how they scale, a description of the typical scaling procedures used in development programs today, and finally a review of several historical development programs to see what insight they can bring to the questions at hand.

  6. Mathematics Anxiety and the Affective Drop in Performance

    ERIC Educational Resources Information Center

    Ashcraft, Mark H.; Moore, Alex M.

    2009-01-01

    The authors provide a brief review of the history and assessment of math anxiety, its relationship to personal and educational consequences, and its important impact on measures of performance. Overall, math anxiety causes an "affective drop," a decline in performance when math is performed under timed, high-stakes conditions, both in laboratory…

  7. Spectroradiometer Intercomparison and Impact on Characterizing Photovoltaic Device Performance: Preprint

    SciTech Connect

    Habte, A.; Andreas, A.; Ottoson, L.; Gueymard, C.; Fedor, G.; Fowler, S.; Peterson, J.; Naranen, E.; Kobashi, T.; Akiyama, A.; Takagi, S.

    2014-11-01

    Indoor and outdoor testing of photovoltaic (PV) device performance requires the use of solar simulators and natural solar radiation, respectively. This performance characterization requires accurate knowledge of spectral irradiance distribution that is incident on the devices. Spectroradiometers are used to measure the spectral distribution of solar simulators and solar radiation. On September 17, 2013, a global spectral irradiance intercomparison using spectroradiometers was organized by the Solar Radiation Research Laboratory (SRRL) at the National Renewable Energy Laboratory (NREL). This paper presents highlights of the results of this first intercomparison, which will help to decrease systematic inter-laboratory differences in the measurements of the outputs or efficiencies of PV devices and harmonize laboratory experimental procedures.

  8. Perfectionism, Performance, and State Positive Affect and Negative Affect after a Classroom Test

    ERIC Educational Resources Information Center

    Flett, Gordon L.; Blankstein, Kirk R.; Hewitt, Paul L.

    2009-01-01

    The current study examined the associations among trait dimensions of perfectionism, test performance, and levels of positive and negative affect after taking a test. A sample of 92 female university students completed the Multidimensional Perfectionism Scale one week prior to an actual class test. Measures of positive affect and negative affect…

  9. Towards Non-thrombogenic Performance of Blood Recirculating Devices

    PubMed Central

    Bluestein, D.; Chandran, K. B.; Manning, K. B.

    2010-01-01

    Implantable blood recirculating devices have provided life saving solutions to patients with severe cardiovascular diseases. However, common problems of hemolysis and thromboembolism remain an impediment to these devices. In this article, we present a brief review of the work by several groups in the field that has led to the development of new methodologies that may facilitate achieving the daunting goal of optimizing the thrombogenic performance of blood recirculating devices. The aim is to describe work which pertains to the interaction between flow-induced stresses and the blood constituents, and that supports the hypothesis that thromboembolism in prosthetic blood recirculating devices is initiated and maintained primarily by the non-physiological flow patterns and stresses that activate and enhance the aggregation of blood platelets, increasing the risk of thromboembolism and cardioembolic stroke. Such work includes state-of-the-art numerical and experimental tools used to elucidate flow-induced mechanisms leading to thromboembolism in prosthetic devices. Following the review, the paper describes several efforts conducted by some of the groups active in the field, and points to several directions that should be pursued in the future in order to achieve the goal for blood recirculating prosthetic devices becoming more effective as destination therapy in the future. PMID:20131098

  10. B2H6 PLAD Doped PMOS Device Performance

    SciTech Connect

    Fang, Z.; Miller, T.; Winder, E.; Persing, H.; Arevalo, E.; Gupta, A.; Parrill, T.; Singh, V.; Qin, S.; McTeer, A.

    2006-11-13

    Plasma doping (PLAD) achieves high wafer throughput by directly extracting ions across the plasma sheath. PLAD profiles are typically surface peaked instead of retrograde as obtained from beamline (BL) implant. It may require optimization of PLAD energy and dose in order to match BL doping results. From device optimization point of view, it is necessary to understand the impact of doping parameters to device characteristics. In this paper we present the PMOS device performance with the poly gate and source drain (SD) implants carried out using B2H6 PLAD. The BL control conditions are 2-5 keV 11B+ 4-6x1015 cm-2. Equivalent device performance for p+ poly gate doping is obtained using PLAD with B2H6 / H2. In SD doping using same gas mixture, nearly 50% reduction in SD contact resistance is observed in the PLAD splits. The reduction in SD contact resistance leads to 10-15% increase in device on-current, hence demonstrating the process advantages of using PLAD in addition to having a high wafer throughput.

  11. Si-photonics based passive device packaging and module performance.

    PubMed

    Song, Jeong Hwan; Zhang, Jing; Zhang, Huijuan; Li, Chao; Lo, Guo Qiang

    2011-09-12

    We report a fully packaged silicon passive waveguide device designed for a tunable filter based on a ring-resonator. Polarization diversity circuits prevent polarization dependant issues in the silicon ring-resonator. For the device packaging, the YAG laser welding technique has been used for pigtailing both of the input and output fibers. Post welding misalignment was compensated by mechanical fine tuning using the seesaw effect via power monitoring. Packaging loss less than 1.5 dB with respect to chip measurement has been achieved using 10 µm-curvature radius lensed fibers. In addition, the packaging process and the module performance are presented. PMID:21935167

  12. Factors Affecting Performance of Undergraduate Students in Construction Related Disciplines

    ERIC Educational Resources Information Center

    Olatunji, Samuel Olusola; Aghimien, Douglas Omoregie; Oke, Ayodeji Emmanuel; Olushola, Emmanuel

    2016-01-01

    Academic performance of students in Nigerian institutions has been of much concern to all and sundry hence the need to assess the factors affecting performance of undergraduate students in construction related discipline in Nigeria. A survey design was employed with questionnaires administered on students in the department of Quantity Surveying,…

  13. Focus of Attention Affects Performance of Motor Skills in Music

    ERIC Educational Resources Information Center

    Duke, Robert A.; Cash, Carla Davis; Allen, Sarah E.

    2011-01-01

    To test the extent to which learners performing a simple keyboard passage would be affected by directing their focus of attention to different aspects of their movements, 16 music majors performed a brief keyboard passage under each of four focus conditions arranged in a counterbalanced design--a total of 64 experimental sessions. As they…

  14. Medical Device Risk Management For Performance Assurance Optimization and Prioritization.

    PubMed

    Gaamangwe, Tidimogo; Babbar, Vishvek; Krivoy, Agustina; Moore, Michael; Kresta, Petr

    2015-01-01

    Performance assurance (PA) is an integral component of clinical engineering medical device risk management. For that reason, the clinical engineering (CE) community has made concerted efforts to define appropriate risk factors and develop quantitative risk models for efficient data processing and improved PA program operational decision making. However, a common framework that relates the various processes of a quantitative risk system does not exist. This article provides a perspective that focuses on medical device quality and risk-based elements of the PA program, which include device inclusion/exclusion, schedule optimization, and inspection prioritization. A PA risk management framework is provided, and previous quantitative models that have contributed to the advancement of PA risk management are examined. A general model for quantitative risk systems is proposed, and further perspective on possible future directions in the area of PA technology is also provided. PMID:26618842

  15. Interface engineering for high performance graphene electronic devices

    NASA Astrophysics Data System (ADS)

    Jung, Dae Yool; Yang, Sang Yoon; Park, Hamin; Shin, Woo Cheol; Oh, Joong Gun; Cho, Byung Jin; Choi, Sung-Yool

    2015-06-01

    A decade after the discovery of graphene flakes, exfoliated from graphite, we have now secured large scale and high quality graphene film growth technology via a chemical vapor deposition (CVD) method. With the establishment of mass production of graphene using CVD, practical applications of graphene to electronic devices have gained an enormous amount of attention. However, several issues arise from the interfaces of graphene systems, such as damage/unintentional doping of graphene by the transfer process, the substrate effects on graphene, and poor dielectric formation on graphene due to its inert features, which result in degradation of both electrical performance and reliability in actual devices. The present paper provides a comprehensive review of the recent approaches to resolve these issues by interface engineering of graphene for high performance electronic devices. We deal with each interface that is encountered during the fabrication steps of graphene devices, from the graphene/metal growth substrate to graphene/high-k dielectrics, including the intermediate graphene/target substrate.

  16. Study of how sash movement affects performance of fume hoods

    SciTech Connect

    Hardwick, T.

    1997-12-31

    This study was conducted to determine how sash movements affect the performance of fume hoods. The performance of two fume hoods was studied as the sashes were moved from closed to open position at speeds of 2 ft/s, 1.5 ft/s, and 1 ft/s. The tests were conducted with fume hoods operated at both constant volume and variable air volume. The tests indicate that sash movements can disturb airflow patterns at the face of the hood and potentially affect the performance of the hood. The effect of the sash movement varied with hood type and speed of sash movement. The faster sash movements of 2 ft/s and 1.5 ft/s had a greater effect on the performance of the hoods than the slower movement of 1 ft/s. Constant-volume hoods and variable-air-volume hoods were both affected by sash movements. Constant-volume hoods set to a full open face velocity of 60 ft/min were more susceptible to the sash movement than at 100 ft/min full open face velocity. The performance of variable-air-volume hoods is affected not only by sash movement speed but also by the response time of the controller. The drop in face velocity that occurs when the sash is moved is determined by the speed of the VAV controller. The required response time for containment depends on the fume hood design and the speed of the sash movement.

  17. Economy Affects Students' Academic Performance as Well as Spending Decisions

    ERIC Educational Resources Information Center

    Sander, Libby

    2012-01-01

    Like many Americans caught up in the economic downturn, college students are worried about money. Now research indicates that financial worries may affect their academic performance. The author presents the results of this year's National Survey of Student Engagement. The survey reveals that more than a third of seniors and more than a quarter of…

  18. Cognitive, Affective, and Behavioral Determinants of Performance: A Process Model.

    ERIC Educational Resources Information Center

    Dorfman, Peter W.; Stephan, Walter G.

    Literature from organizational and social psychology has suggested that three types of factors influence performance, i.e., cognitive, affective and behavioral. A model was developed to test a set of propositions concerning the relationship between the three kinds of factors, and included attributions, expectancies, general emotional responses to…

  19. Principals' Perception regarding Factors Affecting the Performance of Teachers

    ERIC Educational Resources Information Center

    Akram, Muhammad Javaid; Raza, Syed Ahmad; Khaleeq, Abdur Rehman; Atika, Samrana

    2011-01-01

    This study investigated the perception of principals on how the factors of subject mastery, teaching methodology, personal characteristics, and attitude toward students affect the performance of teachers at higher secondary level in the Punjab. All principals of higher secondary level in the Punjab were part of the population of the study. From…

  20. Factors Affecting Performance in an Introductory Sociology Course

    ERIC Educational Resources Information Center

    Kwenda, Maxwell

    2011-01-01

    This study examines factors affecting students' performances in an Introductory Sociology course over five semesters. Employing simple and ordered logit regression models, the author explains final grades by focusing on individual demographic and educational characteristics that students bring into the classroom. The results show that a student's…

  1. Sibsize, Family Environment, Cognitive Performance, and Affective Characteristics

    ERIC Educational Resources Information Center

    Marjoribanks, Kevin

    1976-01-01

    Incorporates measures of family environment (parent-child interaction) into research methodology to study the effects of sibsize (family size and birth order) on a child's cognitive performance and affective behavior. Provides tentative support for the confluence model of sibsize influences on children's behaviors. (RL)

  2. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production

    PubMed Central

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  3. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  4. Dynamic performance of a magnetic levitation haptic device

    NASA Astrophysics Data System (ADS)

    Berkelman, Peter; Hollis, Ralph L.

    1997-12-01

    A new haptic interface device has been developed which uses Lorentz force magnetic levitation for actuation. With this device, the user grasps a floating rigid body to interact with the system. The levitated moving part grasped by the user contains curved oval wound coils and LEDs embedded in a hemispherical shell with a handle fixed at its center. The stationary base contains magnet assemblies facing the flotor coils and optical position sensors facing the flotor LEDs. The device is mounted in the top cover of a desk-side cabinet enclosure containing all the amplifiers, control hardware, microprocessing, and power supplies needed for operation. A network connection provides communication with a workstation to allow interaction with simulated 3D environments in real time. Ideally, the haptic interface device should reproduce the dynamics of the modelled or remote environment with such high fidelity that the user cannot distinguish interaction with the device from interaction with a real object in a real environment. In practice, this ideal can only be approached with a fidelity that depends on its dynamic properties such as position and force bandwidths, maximum forces and accelerations, position resolution, and realizable impedance range. The motion range of the moving part is approximately 25 mm and 15 - 20 degrees in all directions. A current of 0.75 A is required in three of the six coils to generate the vertical force to lift the 850 g levitated mass, dissipating only 13.5 W. Peak forces of over 50 N and torques of over 6 Nm are achievable with the present amplifiers without overheating the actuator coils. Other measured performance results include stiffness ranges from 0.005 N/mm to 25.0 N/mm and a position control bandwidth of approximately 75 Hz.

  5. Socially triggered negative affect impairs performance in simple cognitive tasks.

    PubMed

    Böttcher, Svenja; Dreisbach, Gesine

    2014-03-01

    The aim of this research was to investigate the influence of a social-evaluative context on simple cognitive tasks. While another person present in the room evaluated photographs of beautiful women or landscapes by beauty/attractiveness, female participants had to perform a combination of digit-categorization and spatial-compatibility task. There, before every trial, one of the women or landscape pictures was presented. Results showed selective performance impairments: the numerical distance effects increased on trials that followed women pictures but only, if another person concurrently evaluated these women pictures. In a second experiment, using the affective priming paradigm, the authors show that female pictures have a more negative connotation when they are concurrently evaluated by another person (social-evaluative context) than when they are not evaluated (neutral context). Together, these results suggest that the social-evaluative context triggers mild negative affective reactions to women pictures which then impair performance in an unrelated task. PMID:23423348

  6. Charge-coupled-device X-ray detector performance model

    NASA Technical Reports Server (NTRS)

    Bautz, M. W.; Berman, G. E.; Doty, J. P.; Ricker, G. R.

    1987-01-01

    A model that predicts the performance characteristics of CCD detectors being developed for use in X-ray imaging is presented. The model accounts for the interactions of both X-rays and charged particles with the CCD and simulates the transport and loss of charge in the detector. Predicted performance parameters include detective and net quantum efficiencies, split-event probability, and a parameter characterizing the effective thickness presented by the detector to cosmic-ray protons. The predicted performance of two CCDs of different epitaxial layer thicknesses is compared. The model predicts that in each device incomplete recovery of the charge liberated by a photon of energy between 0.1 and 10 keV is very likely to be accompanied by charge splitting between adjacent pixels. The implications of the model predictions for CCD data processing algorithms are briefly discussed.

  7. Progress in GaN devices performances and reliability

    NASA Astrophysics Data System (ADS)

    Saunier, P.; Lee, C.; Jimenez, J.; Balistreri, A.; Dumka, D.; Tserng, H. Q.; Kao, M. Y.; Chowdhury, U.; Chao, P. C.; Chu, K.; Souzis, A.; Eliashevich, I.; Guo, S.; del Alamo, J.; Joh, J.; Shur, M.

    2008-02-01

    With the DARPA Wide Bandgap Semiconductor Technology RF Thrust Contract, TriQuint Semiconductor and its partners, BAE Systems, Lockheed Martin, IQE-RF, II-VI, Nitronex, M.I.T., and R.P.I. are achieving great progress towards the overall goal of making Gallium Nitride a revolutionary RF technology ready to be inserted in defense and commercial applications. Performance and reliability are two critical components of success (along with cost and manufacturability). In this paper we will discuss these two aspects. Our emphasis is now operation at 40 V bias voltage (we had been working at 28 V). 1250 µm devices have power densities in the 6 to 9 W/mm with associated efficiencies in the low- to mid 60 % and associated gain in the 12 to 12.5 dB at 10 GHz. We are using a dual field-plate structure to optimize these performances. Very good performances have also been achieved at 18 GHz with 400 µm devices. Excellent progress has been made in reliability. Our preliminary DC and RF reliability tests at 40 V indicate a MTTF of 1E6hrs with1.3 eV activation energy at 150 0C channel temperature. Jesus Del Alamo at MIT has greatly refined our initial findings leading to a strain related theory of degradation that is driven by electric fields. Degradation can occur on the drain edge of the gate due to excessive strain given by inverse piezoelectric effect.

  8. The performance of computer input devices in a vibration environment.

    PubMed

    Lin, Chiuhsiang Joe; Liu, Chi No; Chao, Chin Jung; Chen, Hung Jen

    2010-04-01

    This study investigates the performance of a touch screen, mouse and trackball in a motion environment. A Stewart motion platform was used to generate a six-degree-of-freedom motion environment. Participants were placed in an environment where vehicle vibration was simulated. Tasks were used according to Fitts' Law to obtain the movement time, error rate, index of performance and throughput of each input device. The results showed that during static conditions, the touch screen gave the best results. However, in the vibration environment, the mouse gave the best results. The trackball is the worst of the three. The error rate and end-point variation tends to increase for the touch screen in the vibration environment. STATEMENT OF RELEVANCE: This study investigates the performance of a pointing device in a vibration environment. The results showed that during static conditions, the touch screen gave the best results. However, in the vibration environment, the mouse gave the best results. The track ball is the worst of the three. This research achievement can help human-computer interaction design in various dynamic environments such as in sea and land vehicles. PMID:20309744

  9. Factors Affecting Polymer Electrolyte Fuel Cells Performance and Reproducibility

    SciTech Connect

    Moller-Holst S.

    1998-11-01

    Development of fuel cells is often based on small-scale laboratory studies. Due to limited time and budgets, a minimum number of cells are usually prepared and tested, thus, conclusions about improved performance are often drawn from studies of a few cells. Generally, statistics showing the significance of an effect are seldom reported. In this work a simple PEM fuel cell electrode optimization experiment is used as an example to illustrate the importance of statistical evaluation of factors affecting cell performance. The use of fractional factorial design of experiments to reduce the number of cells that have to be studied is also addressed.

  10. Performance of a Thermoelectric Device with Integrated Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Barry, Matthew M.; Agbim, Kenechi A.; Chyu, Minking K.

    2015-06-01

    Thermoelectric devices (TEDs) convert heat directly into electrical energy, making them well suited for waste heat recovery applications. An integrated thermoelectric device (iTED) is a restructured TED that allows more heat to enter the p-n junctions, thus producing a greater power output . An iTED has heat exchangers incorporated into the hot-side interconnectors with flow channels directing the working fluid through the heat exchangers. The iTED was constructed of p- and n-type bismuth-telluride semiconductors and copper interconnectors and rectangular heat exchangers. The performance of the iTED in terms of , produced voltage and current , heat input and conversion efficiency for various flow rates (), inlet temperatures (C) ) and load resistances () with a constant cold-side temperature ( = 0C) was conducted experimentally. An increase in had a greater effect on the performance than did an increase in . A 3-fold increase in resulted in a 3.2-, 3.1-, 9.7-, 3.5- and 2.8-fold increase in and respectively. For a constant of 50C, a 3-fold increase in from 3300 to 9920 resulted in 1.6-, 1.6-, 2.6-, 1.5- and 1.9-fold increases in , , , and respectively.

  11. Novel nano materials for high performance logic and memory devices

    NASA Astrophysics Data System (ADS)

    Das, Saptarshi

    After decades of relentless progress, the silicon CMOS industry is approaching a stall in device performance for both logic and memory devices due to fundamental scaling limitations. In order to reinforce the accelerating pace, novel materials with unique properties are being proposed on an urgent basis. This list includes one dimensional nanotubes, quasi one dimensional nanowires, two dimensional atomistically thin layered materials like graphene, hexagonal boron nitride and the more recently the rich family of transition metal di-chalcogenides comprising of MoS2, WSe2, WS2 and many more for logic applications and organic and inorganic ferroelectrics, phase change materials and magnetic materials for memory applications. Only time will tell who will win, but exploring these novel materials allow us to revisit the fundamentals and strengthen our understanding which will ultimately be beneficial for high performance device design. While there has been growing interest in two-dimensional (2D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancies due to the lack of a complete picture of their performance potential. The fact that the 2-D layered semiconducting di-chalcogenides need to be connected to the "outside" world in order to capitalize on their ultimate potential immediately emphasizes the importance of a thorough understanding of the contacts. This thesis demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS2 layers the excellent intrinsic properties of this 2D material can be harvested. A comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back gated multilayer MoS 2 field effect transistors is also provided. A resistor network model that comprises of Thomas-Fermi charge screening and interlayer coupling is used to explain the non-monotonic trend in the extracted field effect

  12. Novel nano materials for high performance logic and memory devices

    NASA Astrophysics Data System (ADS)

    Das, Saptarshi

    After decades of relentless progress, the silicon CMOS industry is approaching a stall in device performance for both logic and memory devices due to fundamental scaling limitations. In order to reinforce the accelerating pace, novel materials with unique properties are being proposed on an urgent basis. This list includes one dimensional nanotubes, quasi one dimensional nanowires, two dimensional atomistically thin layered materials like graphene, hexagonal boron nitride and the more recently the rich family of transition metal di-chalcogenides comprising of MoS2, WSe2, WS2 and many more for logic applications and organic and inorganic ferroelectrics, phase change materials and magnetic materials for memory applications. Only time will tell who will win, but exploring these novel materials allow us to revisit the fundamentals and strengthen our understanding which will ultimately be beneficial for high performance device design. While there has been growing interest in two-dimensional (2D) crystals other than graphene, evaluating their potential usefulness for electronic applications is still in its infancies due to the lack of a complete picture of their performance potential. The fact that the 2-D layered semiconducting di-chalcogenides need to be connected to the "outside" world in order to capitalize on their ultimate potential immediately emphasizes the importance of a thorough understanding of the contacts. This thesis demonstrate that through a proper understanding and design of source/drain contacts and the right choice of number of MoS2 layers the excellent intrinsic properties of this 2D material can be harvested. A comprehensive experimental study on the dependence of carrier mobility on the layer thickness of back gated multilayer MoS 2 field effect transistors is also provided. A resistor network model that comprises of Thomas-Fermi charge screening and interlayer coupling is used to explain the non-monotonic trend in the extracted field effect

  13. Impact of hearing protection devices on sound localization performance

    PubMed Central

    Zimpfer, Véronique; Sarafian, David

    2014-01-01

    Hearing Protection Devices (HPDs) can protect the ear against loud potentially damaging sounds while allowing lower-level sounds such as speech to be perceived. However, the impact of these devices on the ability to localize sound sources is not well known. To address this question, we propose two different methods: one behavioral and one dealing with acoustical measurements. For the behavioral method, sound localization performance was measured with, and without, HPDs on 20 listeners. Five HPDs, including both passive (non-linear attenuation) and three active (talk-through) systems were evaluated. The results showed a significant increase in localization errors, especially front-back and up-down confusions relative to the “naked ear” test condition for all of the systems tested, especially for the talk-through headphone system. For the acoustic measurement method, Head-Related Transfer Functions (HRTFs) were measured on an artificial head both without, and with the HPDs in place. The effects of the HPDs on the spectral cues for the localization of different sound sources in the horizontal plane were analyzed. Alterations of the Interaural Spectral Difference (ISD) cues were identified, which could explain the observed increase in front-back confusions caused by the talk-through headphone protectors. PMID:24966807

  14. Does Question Structure Affect Exam Performance in the Geosciences?

    NASA Astrophysics Data System (ADS)

    Day, E. A.; D'Arcy, M. K.; Craig, L.; Streule, M. J.; Passmore, E.; Irving, J. C. E.

    2015-12-01

    The jump to university level exams can be challenging for some students, often resulting in poor marks, which may be detrimental to their confidence and ultimately affect their overall degree class. Previous studies have found that question structure can have a strong impact on the performance of students in college level exams (see Gibson et al., 2015, for a discussion of its impact on physics undergraduates). Here, we investigate the effect of question structure on the exam results of geology and geophysics undergraduate students. Specifically, we analyse the performance of students in questions that have a 'scaffolded' framework and compare them to their performance in open-ended questions and coursework. We also investigate if observed differences in exam performance are correlated with the educational background and gender of students, amongst other factors. It is important for all students to be able to access their degree courses, no matter what their backgrounds may be. Broadening participation in the geosciences relies on removing systematic barriers to achievement. Therefore we recommend that exams are either structured with scaffolding in questions at lower levels, or students are explicitly prepared for this transition. We also recommend that longitudinal studies of exam performance are conducted within individual departments, and this work outlines one approach to analysing performance data.

  15. Performance of a malaria microscopy image analysis slide reading device

    PubMed Central

    2012-01-01

    device performs at a level comparable to that of many human slide readers. Because its use requires minimal additional equipment and it uses standard stained slides as starting material, its widespread adoption may eliminate the current uncertainty about the quality of microscopic diagnoses worldwide. PMID:22559294

  16. Aeroacoustic performance of an externally blown flap configuration with several flap noise suppression devices

    NASA Technical Reports Server (NTRS)

    Mckinzie, D. J., Jr.

    1982-01-01

    Small scale model acoustic experiments were conducted to measure the noise produced in the flyover and sideline planes by an engine under the wing externally blown flap configuration in its approach attitude. Broadband low frequency noise reductions as large as 9 dB were produced by reducing the separation distance between the nozzle exhaust plane and the flaps. Experiments were also conducted to determine the noise suppression effectiveness in comparison with a reference configuration of three passive types of devices that were located on the jet impingement surfaces of the reference configuration. These devices produced noise reductions that varied up to 10 dB at reduced separation distances. In addition, a qualitative estimate of the noise suppression characteristics of the separate devices was made. Finally static aerodynamic performance data were obtained to evaluate the penalties incurred by these suppression devices. The test results suggest that further parametric studies are required in order to understand more fully the noise mechanisms that are affected by the suppression devices used.

  17. Aeroacoustic performance of an externally blown flap configuration with several flap noise suppression devices

    NASA Astrophysics Data System (ADS)

    McKinzie, D. J., Jr.

    1982-05-01

    Small scale model acoustic experiments were conducted to measure the noise produced in the flyover and sideline planes by an engine under the wing externally blown flap configuration in its approach attitude. Broadband low frequency noise reductions as large as 9 dB were produced by reducing the separation distance between the nozzle exhaust plane and the flaps. Experiments were also conducted to determine the noise suppression effectiveness in comparison with a reference configuration of three passive types of devices that were located on the jet impingement surfaces of the reference configuration. These devices produced noise reductions that varied up to 10 dB at reduced separation distances. In addition, a qualitative estimate of the noise suppression characteristics of the separate devices was made. Finally static aerodynamic performance data were obtained to evaluate the penalties incurred by these suppression devices. The test results suggest that further parametric studies are required in order to understand more fully the noise mechanisms that are affected by the suppression devices used.

  18. Chemical approaches to the improved performance of nanoelectronic devices

    NASA Astrophysics Data System (ADS)

    Chang, Noel N.

    Although randomly oriented CNT networks and polycrystalline graphene are easy to make and robust towards mechanical deformation, both materials suffer from resistive: at the intertube junctions in CNT networks and at grain boundaries in polycrystalline graphene sheets. In a process we have named "nanosoldering," a conductive material is deposited at the resistive junctions by operating the device in an atmosphere of a chemical precursor. The resistive heating that occurs at the "bad" junctions induces a thermal CVD process. The conductive material that is deposited at these junctions improves the overlap between the two nanotubes and decreases the junction resistance. Two precursors were utilized for this method: CpPd(allyl) to deposit Pd(0) and Hf(BH4)4 to deposit HfB2. In the SEM images post treatment, deposition is observed on many intertube junctions as well as along the lengths of some tubes; the latter can be eliminated by selecting the appropriate experimental conditions. For treatment with the Pd precursor, the ION/IOFF ratio improved by a factor of 6 on average. On the other hand, no improvement was observed for samples treated with the HfB2 precursor due to the large mismatch in work functions between CNTs and HfB2, which creates a Schottky barrier. A solution process was developed to improve the scalability of the nanosoldering process by eliminating the necessity of using a vacuum system and volatile chemical precursors. To do so, a nanosoldering precursor is spin-coated onto the solid substrate. The nanosoldering process is conducted in a commercial available probe station either in air or under vacuum, after which the excess material and byproduct are removed by a solvent rinse. Using this method, we show a comparable degree of device performance improvement using a nonvolatile Pd precursor, Pd2(dba)3. We also obtained improved device performance with a new carbon-based precursor, 1,3,5-tris(2-bromophenyl)benzene. Finally, preliminary experiments were

  19. Performance Testing using Silicon Devices - Analysis of Accuracy: Preprint

    SciTech Connect

    Sengupta, M.; Gotseff, P.; Myers, D.; Stoffel, T.

    2012-06-01

    Accurately determining PV module performance in the field requires accurate measurements of solar irradiance reaching the PV panel (i.e., Plane-of-Array - POA Irradiance) with known measurement uncertainty. Pyranometers are commonly based on thermopile or silicon photodiode detectors. Silicon detectors, including PV reference cells, are an attractive choice for reasons that include faster time response (10 us) than thermopile detectors (1 s to 5 s), lower cost and maintenance. The main drawback of silicon detectors is their limited spectral response. Therefore, to determine broadband POA solar irradiance, a pyranometer calibration factor that converts the narrowband response to broadband is required. Normally this calibration factor is a single number determined under clear-sky conditions with respect to a broadband reference radiometer. The pyranometer is then used for various scenarios including varying airmass, panel orientation and atmospheric conditions. This would not be an issue if all irradiance wavelengths that form the broadband spectrum responded uniformly to atmospheric constituents. Unfortunately, the scattering and absorption signature varies widely with wavelength and the calibration factor for the silicon photodiode pyranometer is not appropriate for other conditions. This paper reviews the issues that will arise from the use of silicon detectors for PV performance measurement in the field based on measurements from a group of pyranometers mounted on a 1-axis solar tracker. Also we will present a comparison of simultaneous spectral and broadband measurements from silicon and thermopile detectors and estimated measurement errors when using silicon devices for both array performance and resource assessment.

  20. Statistical performance of the intensified charged coupled device

    NASA Technical Reports Server (NTRS)

    Sandel, B. R.; Broadfoot, A. L.

    1986-01-01

    The first analysis of the statistical performance of the intensified charge coupled device (CCD) is presented. The Poisson statistics of the arriving photons, the exponential pulse height distribution of the microchannel plate in the image intensifier, and the effects of discrete digitization of the charge in reading the CCD are included. A range of intensifier gains from the high levels that permit pulse counting to the low levels that can be used with the accumulation of charge on the CCD is considered. As a tool for this analysis, an analytical model of the performance of the detector system that is generally useful for predicting many aspects of system performance under a wide range of conditions is developed. The statistical penalty for operating the intensified CCD in the charge accumulation mode is not severe, and in some applications it may be desirable to accept this penalty to gain the advantages of increased dynamic range through charge accumulation. This investigation has revealed no pathological aspects of the operation of the detector system.

  1. Analysis of factors affecting milking claw vacuum levels using a simulated milking device.

    PubMed

    Enokidani, Masafumi; Kuruhara, Kana; Kawai, Kazuhiro

    2016-06-01

    Bovine mastitis is typically caused by microbial infection of the udder, but the factors responsible for this condition are varied. One potential cause is the milking system, and although previous studies have investigated various methods for inspecting these devices, most have not assessed methods for evaluating the milking units. With this in mind, we analyzed the factors that affect the vacuum inside the milking claw by using a simulated milking device and by measuring milking claw vacuum when adjusting the flow rate in five stages. The factors analyzed in each milking system were the vacuum pressure settings (high and low line system) , milk tube length (200-328 cm), aperture diameter (14-22.2 mm), constricted aperture diameter (12 mm), tubing configurations, lift formation (0-80 cm), claw type (bottom and top flow) and use or non-use of a milk sampler. The study findings demonstrated that all of these variables had a significant impact on claw vacuum and suggest that a diagnostic method using a simulated milking device should be considered when inspecting modern milking systems. PMID:26336796

  2. The role of visual deprivation and experience on the performance of sensory substitution devices.

    PubMed

    Stronks, H Christiaan; Nau, Amy C; Ibbotson, Michael R; Barnes, Nick

    2015-10-22

    It is commonly accepted that the blind can partially compensate for their loss of vision by developing enhanced abilities with their remaining senses. This visual compensation may be related to the fact that blind people rely on their other senses in everyday life. Many studies have indeed shown that experience plays an important role in visual compensation. Numerous neuroimaging studies have shown that the visual cortices of the blind are recruited by other functional brain areas and can become responsive to tactile or auditory input instead. These cross-modal plastic changes are more pronounced in the early blind compared to late blind individuals. The functional consequences of cross-modal plasticity on visual compensation in the blind are debated, as are the influences of various etiologies of vision loss (i.e., blindness acquired early or late in life). Distinguishing between the influences of experience and visual deprivation on compensation is especially relevant for rehabilitation of the blind with sensory substitution devices. The BrainPort artificial vision device and The vOICe are assistive devices for the blind that redirect visual information to another intact sensory system. Establishing how experience and different etiologies of vision loss affect the performance of these devices may help to improve existing rehabilitation strategies, formulate effective selection criteria and develop prognostic measures. In this review we will discuss studies that investigated the influence of training and visual deprivation on the performance of various sensory substitution approaches. PMID:26183014

  3. Method and system for reducing device performance degradation of organic devices

    DOEpatents

    Teague, Lucile C.

    2014-09-02

    Methods and systems for reducing the deleterious effects of gate bias stress on the drain current of an organic device, such as an organic thin film transistor, are provided. In a particular aspect, the organic layer of an organic device is illuminated with light having characteristics selected to reduce the gate bias voltage effects on the drain current of the organic device. For instance, the wavelength and intensity of the light are selected to provide a desired recovery of drain current of the organic device. If the characteristics of the light are appropriately matched to the organic device, recovery of the deleterious effects caused by gate bias voltage stress effects on the drain current of the organic device can be achieved. In a particular aspect, the organic device is selectively illuminated with light to operate the organic device in multiple modes of operation.

  4. Can small shifts in circadian phase affect performance?

    PubMed Central

    Burgess, Helen J.; Legasto, Carlo S.; Fogg, Louis F.; Smith, Mark R.

    2012-01-01

    Small shifts in circadian timing occur frequently as a result of daylight saving time or later weekend sleep. These subtle shifts in circadian phase have been shown to influence subjective sleepiness, but it remains unclear if they can significantly affect performance. In a retrospective analysis we examined performance on the Psychomotor Vigilance Test before bedtime and after wake time in 11 healthy adults on fixed sleep schedules based on their habitual sleep times. The dim light melatonin onset, a marker of circadian timing, was measured on two occasions. An average 1.1 hour shift away from a proposed optimal circadian phase angle (6 hours between melatonin onset and midpoint of sleep) significantly slowed mean, median and fastest 10% reaction times before bedtime and after wake time (p<0.05). These results add to previous reports that suggest that humans may be sensitive to commonly occurring small shifts in circadian timing. PMID:22695081

  5. High-Performance Permanent Magnets for Energy-Efficient Devices

    NASA Astrophysics Data System (ADS)

    Hadjipanayis, George

    2012-02-01

    Permanent magnets (PMs) are indispensable for many commercial applications including the electric, electronic and automobile industries, communications, information technologies and automatic control engineering. In most of these applications, an increase in the magnetic energy density of the PM, usually presented via the maximum energy product (BH)max, immediately increases the efficiency of the whole device and makes it smaller and lighter. Worldwide demand for high performance permanent magnets has increased dramatically in the past few years driven by hybrid and electric cars, wind turbines and other power generation systems. New energy challenges in the world require devices with higher energy efficiency and minimum environmental impact. The potential of 3d-4f compounds which revolutionized the PM science and technology is almost fully utilized, and the supply of 4f rare earth elements does not seem to be much longer assured. This talk will address the major principles guiding the development of PMs and overview state-of-the-art theoretical and experimental research. Recent progress in the development of nanocomposite PMs, consisting of a fine (at the scale of the magnetic exchange length) mixture of phases with high magnetization and large magnetic hardness will be discussed. Fabrication of such PMs is currently the most promising way to boost the (BH)max, while simultaneously decreasing, at least partially, the reliance on the rare earth elements. Special attention will be paid to the impact which the next-generation high-(BH)max magnets is expected to have on existing and proposed energy-saving technologies.

  6. Crystal structure engineering for improved performance of emerging nanoscale devices

    NASA Astrophysics Data System (ADS)

    Chimalgi, Vinay Uday

    Recent advances in growth techniques and increasing number of experimental studies have made nanostructures grown along different crystallographic directions a reality. These new structures could not only benefit the electronic devices used in mainstream information technology but also show great promise for applications in lasers, solid-state lighting, near-field photolithography, free-space quantum cryptography, consumer displays, quantum computation, as well as diagnostic medicine and imaging. However, only few theoretical investigations have been performed on these structures due to the complex nature of the interplay of atomicity, structural fields, polarization, and quantum size-quantization, all strong function of the crystallographic direction. The objective of this work is mainly four-fold: (1) Integrate a computational framework employing a combination of fully atomistic valence force-field molecular mechanics and 20-band sp3s*d5-SO tight-binding based electronic band­structure models, and numerically investigate the effects of internal fields on the electronic and optical properties of zincblende InAs/GaAs quantum dots grown on (100), (110), and (111) orientated substrates. (2) Augment/extend the open source NEMO 3-D bandstructure simulator by incorporating a recently proposed first principles based model to gauge the importance of nonlinear piezoelectricity on the single-particle electronic states and interband optical transitions in emerging In(Ga)N/GaN disk-in-wire LED structures having c-plane and m-plane wurtzite crystal symmetry. (3) Coupling the NEMO 3-D software toolkit with a commercial TCAD simulator to determine the terminal electrical and optical characteristics of InGaN/GaN disk-in-wire LEDs; and (4) Finding an optimum crystallographic device for InGaN/GaN disk-in-wire LEDs to achieve improved internal quantum efficiency (IQE).

  7. High-Performance Radio Frequency Passive Devices on Plastic Substrates for Radio Frequency Integrated Circuit Application

    NASA Astrophysics Data System (ADS)

    Hung, Bing-Fang; Chen, Chia-Chung; Kao, Hsuan-Ling; Chin, Albert

    2007-04-01

    High-performance passive RF devices were fabricated on insulating plastic substrates. These passive devices included inductors, low-loss coplanar waveguide (CPW) and microstrip transmission lines, 30 GHz narrow-band filters, and 25 GHz CPW ring resonators. The characteristics of these devices agreed well with those of ideal devices, as predicted by electro-magnetic simulations.

  8. Influence of material quality and process-induced defects on semiconductor device performance and yield

    NASA Technical Reports Server (NTRS)

    Porter, W. A.; Mckee, W. R.

    1974-01-01

    An overview of major causes of device yield degradation is presented. The relationships of device types to critical processes and typical defects are discussed, and the influence of the defect on device yield and performance is demonstrated. Various defect characterization techniques are described and applied. A correlation of device failure, defect type, and cause of defect is presented in tabular form with accompanying illustrations.

  9. Students' Interest in Surgery Affects Laparoscopic Practicing Performance

    PubMed Central

    Mao Wu, Sheng; Kuei Chien, Wen; Sheng Huang, Chen; Cheng Lin, Wei; Chun Chang, Yin

    2016-01-01

    Background and Objective: Earlier exposure to laparoscopic techniques is thought to be beneficial for medical students. Reports have demonstrated that practice improves performance in laparoscopies. In this study, we intended to evaluate whether medical students' interest in surgery is affected by the amount of practice and the performance on a laparoscopic simulator. Methods: A laparoscopic simulation curriculum was introduced at Taipei Medical University, Wan-Fang Medical Center. Study participants included 36 sixth-year and 14 seventh-year students who were divided according to whether they had indicated an interest (group A) or not (group B) in surgery. The students had twice-a-week practice sessions for 2 weeks. They underwent baseline measurement (BM) before training and posttraining measurement (PTM). Self-guided practice on the simulator was allowed. The learning outcomes were assessed comparing the BM and PTM scores by using the interquartile range (IQR) test. We also tested the correlation between total score and number of self-guided practice sessions. Results: All study participants showed improvement. No differences were observed between BM and PTM scores and between 6th- and 7th-year medical students. Significant differences were found in PTM scores between groups A and B (P < .001). Analysis of variance with a post hoc test for different groups revealed that the PTMs were significantly higher for both the 6th- and 7th-year medical students in group A than for those in group B (P < .001). Total performance scores were improved with a higher number of self-guided practice sessions. Linear regression analysis demonstrated a significant correlation between the number of self-guided practice sessions and total performance score (P < .001). Conclusion: Those clerks and interns interested in surgery who had more sessions for self-guided practice, displayed more improvement than those not interested in surgery did. Improvement in performance correlated

  10. Lithium-oxygen batteries-Limiting factors that affect performance

    NASA Astrophysics Data System (ADS)

    Padbury, Richard; Zhang, Xiangwu

    2011-05-01

    Lithium-oxygen batteries have recently received attention due to their extremely high theoretical energy densities, which far exceed that of any other existing energy storage technology. The significantly larger theoretical energy density of the lithium-oxygen batteries is due to the use of a pure lithium metal anode and the fact that the cathode oxidant, oxygen, is stored externally since it can be readily obtained from the surrounding air. Before the lithium-oxygen batteries can be realized as high performance, commercially viable products, there are still many challenges to overcome, from designing their cathode structure, to optimizing their electrolyte compositions and elucidating the complex chemical reactions that occur during charge and discharge. The scientific obstacles that are related to the performance of the lithium-oxygen batteries open up an exciting opportunity for researchers from many different backgrounds to utilize their unique knowledge and skills to bridge the knowledge gaps that exist in current research projects. This article is a summary of the most significant limiting factors that affect the performance of the lithium-oxygen batteries from the perspective of the authors. The article indicates the relationships that form between various limiting factors and highlights the complex yet captivating nature of the research within this field.

  11. Method and devices for performing stereotactic microbeam radiation therapy

    DOEpatents

    Dilmanian, F. Avraham

    2010-01-05

    A radiation delivery system generally includes either a synchrotron source or a support frame and a plurality of microbeam delivery devices supported on the support frame, both to deliver a beam in a hemispherical arrangement. Each of the microbeam delivery devices or synchrotron irradiation ports is adapted to deliver at least one microbeam of radiation along a microbeam delivery axis, wherein the microbeam delivery axes of the plurality of microbeam delivery devices cross within a common target volume.

  12. II-VI Materials-Based High Performance Intersubband Devices

    NASA Astrophysics Data System (ADS)

    Ravikumar, Arvind Pawan

    achieve normal-incident absorption, taking advantage of light-scattering in sloped surfaces; this method is wavelength independent and does not involve complicated fabrication techniques. With the performance of II-VI devices matching or surpassing existing commercial solutions, integrated mid-IR photonics based sensing is poised to play a big role in the future of sensing technologies.

  13. Lagrangian methods for blood damage estimation in cardiovascular devices - How numerical implementation affects the results.

    PubMed

    Marom, Gil; Bluestein, Danny

    2016-02-01

    This paper evaluated the influence of various numerical implementation assumptions on predicting blood damage in cardiovascular devices using Lagrangian methods with Eulerian computational fluid dynamics. The implementation assumptions that were tested included various seeding patterns, stochastic walk model, and simplified trajectory calculations with pathlines. Post processing implementation options that were evaluated included single passage and repeated passages stress accumulation and time averaging. This study demonstrated that the implementation assumptions can significantly affect the resulting stress accumulation, i.e., the blood damage model predictions. Careful considerations should be taken in the use of Lagrangian models. Ultimately, the appropriate assumptions should be considered based the physics of the specific case and sensitivity analysis, similar to the ones presented here, should be employed. PMID:26679833

  14. Irrelevant events affect voters' evaluations of government performance

    PubMed Central

    Healy, Andrew J.; Malhotra, Neil; Mo, Cecilia Hyunjung

    2010-01-01

    Does information irrelevant to government performance affect voting behavior? If so, how does this help us understand the mechanisms underlying voters’ retrospective assessments of candidates’ performance in office? To precisely test for the effects of irrelevant information, we explore the electoral impact of local college football games just before an election, irrelevant events that government has nothing to do with and for which no government response would be expected. We find that a win in the 10 d before Election Day causes the incumbent to receive an additional 1.61 percentage points of the vote in Senate, gubernatorial, and presidential elections, with the effect being larger for teams with stronger fan support. In addition to conducting placebo tests based on postelection games, we demonstrate these effects by using the betting market's estimate of a team's probability of winning the game before it occurs to isolate the surprise component of game outcomes. We corroborate these aggregate-level results with a survey that we conducted during the 2009 NCAA men's college basketball tournament, where we find that surprising wins and losses affect presidential approval. An experiment embedded within the survey also indicates that personal well-being may influence voting decisions on a subconscious level. We find that making people more aware of the reasons for their current state of mind reduces the effect that irrelevant events have on their opinions. These findings underscore the subtle power of irrelevant events in shaping important real-world decisions and suggest ways in which decision making can be improved. PMID:20615955

  15. Irrelevant events affect voters' evaluations of government performance.

    PubMed

    Healy, Andrew J; Malhotra, Neil; Mo, Cecilia Hyunjung

    2010-07-20

    Does information irrelevant to government performance affect voting behavior? If so, how does this help us understand the mechanisms underlying voters' retrospective assessments of candidates' performance in office? To precisely test for the effects of irrelevant information, we explore the electoral impact of local college football games just before an election, irrelevant events that government has nothing to do with and for which no government response would be expected. We find that a win in the 10 d before Election Day causes the incumbent to receive an additional 1.61 percentage points of the vote in Senate, gubernatorial, and presidential elections, with the effect being larger for teams with stronger fan support. In addition to conducting placebo tests based on postelection games, we demonstrate these effects by using the betting market's estimate of a team's probability of winning the game before it occurs to isolate the surprise component of game outcomes. We corroborate these aggregate-level results with a survey that we conducted during the 2009 NCAA men's college basketball tournament, where we find that surprising wins and losses affect presidential approval. An experiment embedded within the survey also indicates that personal well-being may influence voting decisions on a subconscious level. We find that making people more aware of the reasons for their current state of mind reduces the effect that irrelevant events have on their opinions. These findings underscore the subtle power of irrelevant events in shaping important real-world decisions and suggest ways in which decision making can be improved. PMID:20615955

  16. Factors Affecting Exercise Test Performance in Patients After Liver Transplantation

    PubMed Central

    Kotarska, Katarzyna; Wunsch, Ewa; Jodko, Lukasz; Raszeja-Wyszomirska, Joanna; Bania, Izabela; Lawniczak, Malgorzata; Bogdanos, Dimitrios; Kornacewicz-Jach, Zdzislawa; Milkiewicz, Piotr

    2016-01-01

    Background Cardiovascular diseases are a leading cause of morbidity and mortality in solid organ transplant recipients. In addition, low physical activity is a risk factor for cardiac and cerebrovascular complications. Objectives This study examined potential relationships between physical activity, health-related quality of life (HRQoL), risk factors for cardiovascular disease, and an exercise test in liver-graft recipients. Patients and Methods A total of 107 participants (62 men/45 women) who had received a liver transplantation (LT) at least 6 months previously were evaluated. Physical activity was assessed using three different questionnaires, while HRQoL was assessed using the medical outcomes study short form (SF)-36 questionnaire, and health behaviors were evaluated using the health behavior inventory (HBI). The exercise test was performed in a standard manner. Results Seven participants (6.5%) had a positive exercise test, and these individuals were older than those who had a negative exercise test (P = 0.04). A significant association between a negative exercise test and a higher level of physical activity was shown by the Seven-day physical activity recall questionnaire. In addition, HRQoL was improved in various domains of the SF-36 in participants who had a negative exercise test. No correlations between physical activity, the exercise test and healthy behaviors, as assessed via the HBI were observed. Conclusions Exercise test performance was affected by lower quality of life and lower physical activity after LT. With the exception of hypertension, well known factors that affect the risk of coronary artery disease had no effect on the exercise test results. PMID:27226801

  17. 40 CFR 1700.14 - Marine Pollution Control Device (MPCD) Performance Standards. [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Marine Pollution Control Device (MPCD... DISCHARGE STANDARDS FOR VESSELS OF THE ARMED FORCES Marine Pollution Control Device (MPCD) Performance Standards § 1700.14 Marine Pollution Control Device (MPCD) Performance Standards....

  18. 40 CFR 1700.14 - Marine Pollution Control Device (MPCD) Performance Standards. [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Marine Pollution Control Device (MPCD... DISCHARGE STANDARDS FOR VESSELS OF THE ARMED FORCES Marine Pollution Control Device (MPCD) Performance Standards § 1700.14 Marine Pollution Control Device (MPCD) Performance Standards....

  19. 40 CFR 1700.14 - Marine Pollution Control Device (MPCD) Performance Standards. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Marine Pollution Control Device (MPCD... DISCHARGE STANDARDS FOR VESSELS OF THE ARMED FORCES Marine Pollution Control Device (MPCD) Performance Standards § 1700.14 Marine Pollution Control Device (MPCD) Performance Standards....

  20. 40 CFR 1700.14 - Marine Pollution Control Device (MPCD) Performance Standards. [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Marine Pollution Control Device (MPCD... DISCHARGE STANDARDS FOR VESSELS OF THE ARMED FORCES Marine Pollution Control Device (MPCD) Performance Standards § 1700.14 Marine Pollution Control Device (MPCD) Performance Standards....

  1. 40 CFR 1700.14 - Marine Pollution Control Device (MPCD) Performance Standards. [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Marine Pollution Control Device (MPCD... DISCHARGE STANDARDS FOR VESSELS OF THE ARMED FORCES Marine Pollution Control Device (MPCD) Performance Standards § 1700.14 Marine Pollution Control Device (MPCD) Performance Standards....

  2. Device performance simulations of multilayer black phosphorus tunneling transistors

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Shi, Qing; Wang, Jian; Guo, Hong

    2015-11-01

    We report a theoretical investigation of ballistic transport in multilayer black phosphorus (BP) tunneling transistors (TFETs) with HfO2 as the gate oxide. First-principles calculations show that monolayer BP can be preserved well on HfO2 (111) surface. For a better device performance, the optimum layer and transport direction at different channel lengths are investigated. It is shown that BP TFETs have larger drain current in the armchair direction (AD) than in the zigzag direction, and the current difference can be several orders of magnitude. On-state current can be enhanced in the BP TFETs using thicker BP film, while the minimal leakage current is increased at the same time. To reduce the leakage current and subthreshold swing in the multilayer BP TFETs, lower source/drain doping concentration and smaller drain voltage should be applied. Compared to monolayer MoS2, MoSe2, and MoTe2 TFETs monolayer BP TFETs in AD can reach larger on-state current at the same Ion/Ioff ratio.

  3. Electron Transport Materials: Synthesis, Properties and Device Performance

    SciTech Connect

    Cosimbescu, Lelia; Wang, Liang; Helm, Monte L.; Polikarpov, Evgueni; Swensen, James S.; Padmaperuma, Asanga B.

    2012-06-01

    We report the design, synthesis and characterization, thermal and photophysical properties of two silane based electron transport materials, dibenzo[b,d]thiophen-2-yltriphenylsilane (Si{phi}87) and (dibenzo[b,d]thiophen-2-yl)diphenylsilane (Si{phi}88) and their performance in blue organic light emitting devices (OLEDs). The utility of these materials in blue OLEDs with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C']picolinate (Firpic) as the phosphorescent emitter was demonstrated. Using the silane Si{phi}87 as the electron transport material (ETm) an EQE of 18.2% was obtained, with a power efficiency of 24.3 lm/W (5.8V at 1mA/cm{sup 2}), in a heterostructure. When Si{phi}88 is used, the EQE is 18.5% with a power efficiency of 26.0 lm/W (5.5V at 1mA/cm{sup 2}).

  4. Field Performance of a Newly Developed Upflow Filtration Device

    EPA Science Inventory

    The objective of this research is to examine the removal capacities of a newly developed Upflow filtration device for treatment of stormwater. The device was developed by engineers at the University of Alabama through a Small Business Innovative Research (SBIR) grant from the U....

  5. Performance of device-independent quantum key distribution

    NASA Astrophysics Data System (ADS)

    Cao, Zhu; Zhao, Qi; Ma, Xiongfeng

    2016-07-01

    Quantum key distribution provides information-theoretically-secure communication. In practice, device imperfections may jeopardise the system security. Device-independent quantum key distribution solves this problem by providing secure keys even when the quantum devices are untrusted and uncharacterized. Following a recent security proof of the device-independent quantum key distribution, we improve the key rate by tightening the parameter choice in the security proof. In practice where the system is lossy, we further improve the key rate by taking into account the loss position information. From our numerical simulation, our method can outperform existing results. Meanwhile, we outline clear experimental requirements for implementing device-independent quantum key distribution. The maximal tolerable error rate is 1.6%, the minimal required transmittance is 97.3%, and the minimal required visibility is 96.8 % .

  6. The eccentricity effect: target eccentricity affects performance on conjunction searches.

    PubMed

    Carrasco, M; Evert, D L; Chang, I; Katz, S M

    1995-11-01

    The serial pattern found for conjunction visual-search tasks has been attributed to covert attentional shifts, even though the possible contributions of target location have not been considered. To investigate the effect of target location on orientation x color conjunction searches, the target's duration and its position in the display were manipulated. The display was present either until observers responded (Experiment 1), for 104 msec (Experiment 2), or for 62 msec (Experiment 3). Target eccentricity critically affected performance: A pronounced eccentricity effect was very similar for all three experiments; as eccentricity increased, reaction times and errors increased gradually. Furthermore, the set-size effect became more pronounced as target eccentricity increased, and the extent of the eccentricity effect increased for larger set sizes. In addition, according to stepwise regressions, target eccentricity as well as its interaction with set size were good predictors of performance. We suggest that these findings could be explained by spatial-resolution and lateral-inhibition factors. The serial self-terminating hypothesis for orientation x color conjunction searches was evaluated and rejected. We compared the eccentricity effect as well as the extent of the orientation asymmetry in these three conjunction experiments with those found in feature experiments (Carrasco & Katz, 1992). The roles of eye movements, spatial resolution, and covert attention in the eccentricity effect, as well as their implications, are discussed. PMID:8539099

  7. Distraction affects the performance of obstacle avoidance during walking.

    PubMed

    Weerdesteyn, V; Schillings, A M; van Galen, G P; Duysens, J

    2003-03-01

    In this study, dual-task interference in obstacle-avoidance tasks during human walking was examined. Ten healthy young adults participated in the experiment. While they were walking on a treadmill, an obstacle suddenly fell on the treadmill in front of their left leg during either midswing, early stance, or late stance of the ipsilateral leg. Participants were instructed to avoid the obstacle, both as a single task and while they were concurrently performing a cognitive secondary task (dual task). Rates of failure, avoidance strategy, and a number of kinematic parameters were studied under both task conditions. When only a short response time was available, rates of failure on the avoidance task were larger during the dual task than during the single task. Smaller crossing swing velocities were found during the dual task as compared with those observed in the single task. The difference in crossing swing velocities was attributable to increased stiffness of the crossing swing limb. The results of the present study indicated that divided attention affects young and healthy individuals' obstacle-avoidance performance during walking. PMID:12724099

  8. Outdoor performance testing of thin-film devices

    NASA Technical Reports Server (NTRS)

    1985-01-01

    The Advanced Systems Research Group supports the photovoltaic advanced R&D (PV AR&D) project by providing outdoor (global) testing of PV cells, submodules, modules, and arrays. The group also provides in house engineering and analysis to identify and determine how technical issues such as cell/module/system adaptations, long term stability, reliability, economics, materials availability, safety, and environmental impacts affect the development and ultimate use of advanced PV thin film, innovative cell, and material technologies. A major thrust of the research effort is to develop and utilize instrumentation and procedures for monitoring and analyzing PV cells and submodules including outdoor performance and stability testing and life cycle accelerated stress testing. To accomplish the above, the solar energy research institute (SERI) outdoor PV test facility was established in 1982. The group has designed testing systems and analysis procedures for, and has tested, numerous amorphous silicon thin film submodules provided by SERI subcontractors and has performed long term outdoor stability tests on CdS/CuIr Se sub 2 and hydrogen passivated silicon solar cells. A significant contribution from this facility over the past year was the testing of large area amorphous silicon submodules.

  9. Effect of relative humidity on crystal growth, device performance and hysteresis in planar heterojunction perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Gangishetty, Mahesh K.; Scott, Robert W. J.; Kelly, Timothy L.

    2016-03-01

    Due to the hygroscopic nature of organolead halide perovskites, humidity is one of the most important factors affecting the efficiency and longevity of perovskite solar cells. Although humidity has a long term detrimental effect on device performance, it also plays a key role during the initial growth of perovskite crystals. Here we demonstrate that atmospheric relative humidity (RH) plays a key role during the formation of perovskite thin films via the sequential deposition technique. Our results indicate that the RH has a substantial impact on the crystallization process, and hence on device performance. SEM and pXRD analysis show an increase in crystallite size with increasing humidity. At low RH, the formation of small cubic crystallites with large gaps between them is observed. The presence of these voids adversely affects device performance and leads to substantial hysteresis in the device. At higher RH, the perovskite crystals are larger in size, with better connectivity between the crystallites. This produced efficient planar heterojunction solar cells with low hysteresis. By careful control of the RH during the cell fabrication process, efficiencies of up to 12.2% are reached using P3HT as the hole-transport material.Due to the hygroscopic nature of organolead halide perovskites, humidity is one of the most important factors affecting the efficiency and longevity of perovskite solar cells. Although humidity has a long term detrimental effect on device performance, it also plays a key role during the initial growth of perovskite crystals. Here we demonstrate that atmospheric relative humidity (RH) plays a key role during the formation of perovskite thin films via the sequential deposition technique. Our results indicate that the RH has a substantial impact on the crystallization process, and hence on device performance. SEM and pXRD analysis show an increase in crystallite size with increasing humidity. At low RH, the formation of small cubic crystallites

  10. Silicon Carbide Power Device Performance Under Heavy-Ion Irradiation

    NASA Technical Reports Server (NTRS)

    Lauenstein, Jean-Marie; Casey, Megan; Topper, Alyson; Wilcox, Edward; Phan, Anthony; Ikpe, Stanley; LaBel, Ken

    2015-01-01

    Heavy-ion induced degradation and catastrophic failure data for SiC power MOSFETs and Schottky diodes are examined to provide insight into the challenge of single-event effect hardening of SiC power devices.

  11. Transparent stacked organic light emitting devices. II. Device performance and applications to displays

    NASA Astrophysics Data System (ADS)

    Gu, G.; Parthasarathy, G.; Tian, P.; Burrows, P. E.; Forrest, S. R.

    1999-10-01

    Vertical stacking of organic light emitting devices (OLEDs) that emit the three primary colors is shown to be a means for achieving efficient and bright full-color displays. In Paper I, we addressed stacked OLED (SOLED) design and fabrication principles to optimize emission colors, operating voltage, and efficiency. Here, we present results on two different (metal-containing and metal-free cathode) SOLED structures that exhibit performance suitable for many full-color display applications. The operating voltages at 10 mA/cm2 (corresponding to video display brightnesses) are 6.8, 8.5, and 12.1 V for the red (R), green (G), and blue (B) elements of the metal-containing SOLED, respectively. The respective subpixel luminous efficiencies are 0.53, 1.44, and 1.52 cd/A, and the Commission Internationale de L'Éclairage (CIE) chromaticity coordinates are (0.72, 0.28), (0.42, 0.56), and (0.20, 0.22). In the high transparency metal-free SOLED, an insulating layer was inserted between the two upper subpixels to allow for independent grounding of all color emitters in the stack. At operating voltages of 12-14 V, video display brightnesses were achieved with luminous efficiencies of 0.35, 1.36, and 1.05 cd/A for the R, G, and B subpixels, respectively. The respective CIE coordinates for R, G, and B emissions are (0.72, 0.28), (0.26, 0.63), and (0.17, 0.28) in the normal viewing direction, shifting inperceptibly as the viewing angle is increased to as large as 60°. Finally, we discuss addressing schemes of SOLED displays, and compare them with other strategies for achieving full-color, OLED-based displays.

  12. Silicon device performance measurements to support temperature range enhancement

    NASA Technical Reports Server (NTRS)

    Bromstead, James; Weir, Bennett; Cosby, Melvin; Johnson, R. Wayne; Nelms, R. Mark; Askew, Ray

    1992-01-01

    Characterization results of a MOS controlled thyristor (MCTA60P60) are presented. This device is rated for 60A and for an anode to cathode voltage of -600 V. As discussed in the last report, the MCT failed during 500 V leakage tests at 200 C. In contrast to the BJT (bipolar junction transistor), MOSFET, and IGBT (insulated gate bipolar transistor) devices tested, the breakdown voltage of the MCT decreases significantly with increasing temperature.

  13. Fabrication and performance of contamination free individual single-walled carbon nanotube optical devices.

    PubMed

    Zhou, Yuxiu; Cheng, Rong; Liu, Jianqiang; Li, Tie

    2014-06-01

    Contamination free individual single-walled carbon nanotube (SWCNT) optical devices are fabricated using a hybrid method in the purpose of increase sensitivity as well as further understanding the sensing mechanism. The devices were tested in vacuum to avoid contamination. Three typical devices are discussed comparatively. Under infrared lamp illumination, photovoltaic and photoconductive properties are revealed in device A and B respectively, while device C shows no detectable signal. The photoresponse of device B reaches 108% at 78 K, much larger than that of horizontally aligned or network carbon nanotube devices, indicating priority of the individual nanotube device structure. Interestingly, the temperature characteristics of device A and B are just the opposite. The individual SWCNT devices hold promise in high performance and low cost optical sensors as well as nano-scale solar cells. PMID:24738376

  14. Oligosaccharides Affect Performance and Gut Development of Broiler Chickens

    PubMed Central

    Ao, Z.; Choct, M.

    2013-01-01

    The effects of oligosaccharide supplementation on the growth performance, flock uniformity and GIT development of broiler chickens were investigated. Four diets, one negative control, one positive control supplemented with zinc-bacitracin, and two test diets supplemented with mannoligosaccharide (MOS) and fructooligosaccharide (FOS), were used for the experiment. Birds given MOS or FOS had improved body weight (BW) and feed efficiency (FCR), compared to those fed the negative control diet during the 35-d trial period. The effect on FCR became less apparent when the birds got older. FOS and MOS supplementation reduced the pancreas weight as a percentage of BW, with an effect similar to that of the antibiotic, at 35 d of age. Birds given MOS tended to have a heavier bursa (p = 0.164) and lower spleen/bursa weight ratio (p = 0.102) at 35 d of age. MOS and Zn-bacitracin showed a clear improvement on flock uniformity, compared to FOS. The mortality rate was not affected by FOS or MOS. PMID:25049713

  15. Usefulness of a device for body support during operations performed while standing.

    PubMed

    Ito, Kiyoshi; Horiuchi, Tetsuyoshi; Seguchi, Tatsuya; Hongo, Kazuhiro

    2015-10-01

    During microsurgical procedures, manipulations are often performed using a foot switch while the surgeon stands on one foot. This position can easily result in body axis instability and greater musculoskeletal loading. To support the surgeon's posture, we have developed a tool called the "Surgeon's Body Support Device." The objective of this study was to determine the efficacy of this device by analyzing surgeons' kinematics and musculoskeletal loading during simulated operations undertaken while standing. Fourteen surgeons volunteered to perform simulations of surgery while standing. To analyze motion kinetics and musculoskeletal loading with and without this device, a three-axis accelerometer and surface electromyography (SEMG) sensors were attached to the subjects. Compared with not using the supportive device, the axis of the surgeon's body was significantly more stable when the support device was used (P = .001). The evenness of motion also tended to be superior when the device was utilized (P = .009). Simulations performed using the device significantly reduced the musculoskeletal loading on the ventral side of the left foot by 70 % compared with simulations performed not using the device (P = .001). Data from SEMG sensor placed on the right hand, which performs the surgical manipulations, indicated that simulations performed using the device generated approximately 10 % of the musculoskeletal load generated when the device was not used (P = .001). The Surgeon's Body Support Device appears to improve maneuverability and reduce musculoskeletal loading during simulated surgical procedures undertaken while standing. PMID:25862668

  16. Interaction Between Optical and Neural Factors Affecting Visual Performance

    NASA Astrophysics Data System (ADS)

    Sabesan, Ramkumar

    The human eye suffers from higher order aberrations, in addition to conventional spherical and cylindrical refractive errors. Advanced optical techniques have been devised to correct them in order to achieve superior retinal image quality. However, vision is not completely defined by the optical quality of the eye, but also depends on how the image quality is processed by the neural system. In particular, how neural processing is affected by the past visual experience with optical blur has remained largely unexplored. The objective of this thesis was to investigate the interaction of optical and neural factors affecting vision. To achieve this goal, pathological keratoconic eyes were chosen as the ideal population to study since they are severely afflicted by degraded retinal image quality due to higher order aberrations and their neural system has been exposed to that habitually for a long period of time. Firstly, we have developed advanced customized ophthalmic lenses for correcting the higher order aberration of keratoconic eyes and demonstrated their feasibility in providing substantial visual benefit over conventional corrective methodologies. However, the achieved visual benefit was significantly smaller than that predicted optically. To better understand this, the second goal of the thesis was set to investigate if the neural system optimizes its underlying mechanisms in response to the long-term visual experience with large magnitudes of higher order aberrations. This study was facilitated by a large-stroke adaptive optics vision simulator, enabling us to access the neural factors in the visual system by manipulating the limit imposed by the optics of the eye. Using this instrument, we have performed a series of experiments to establish that habitual exposure to optical blur leads to an alteration in neural processing thereby alleviating the visual impact of degraded retinal image quality, referred to as neural compensation. However, it was also found that

  17. Evaluation of the performance of orthodontic devices using FBG sensors

    NASA Astrophysics Data System (ADS)

    Carvalho, L.; Roriz, P.; Frazão, O.; Marques, M. B.

    2015-04-01

    Cross-bite, as a malocclusion effect, is defined as a transversal changing of the upper dental arch, in relation to the lower arch, and may be classified as skeletal, dental or functional. As a consequence, the expansion of maxilla is an effective clinical treatment used to correct transversal maxillary discrepancy. The maxillary expansion is an ancient method used in orthodontics, for the correction of the maxillary athresia with posterior crossbite, through the opening of the midpalatal suture (disjunction), using orthodontic- orthopaedic devices. Same controversial discussion arises among the clinicians, about the effects of each orthodontic devices as also about the technique to be employed. The objective of this study was to compare the strain field induced by two different orthodontic devices, named disjunctor with and without a connecting bar, in an acrylic model jaw, using fiber Bragg grating sensors to measure the strain patterns. The orthodontic device disjunctor with the bar, in general, transmits higher forces and strain to teeth and maxillae, than with the disjunctor without bar. It was verified that the strain patterns were not symmetric between the left and the right sides as also between the posterior and anterior regions of the maxillae. For the two devices is also found that in addition a displacement in the horizontal plane, particularly in posterior teeth, also occurs a rotation corresponding to a vestibularization of the posterior teeth and their alveolar processes.

  18. Silicon device performance measurements to support temperature range enhancement

    NASA Technical Reports Server (NTRS)

    Bromstead, James; Weir, Bennett; Johnson, R. Wayne; Askew, Ray

    1991-01-01

    Semiconductor power devices are typically rated for operation below 150 C. Little data is known for power semiconductors over 150 C. In most cases, the device is derated to zero operating power at 175 C. At the high temperature end of the temperature range, the intrinsic carrier concentration increases to equal the doping concentration level and the silicon behaves as an intrinsic semiconductor. The increase in intrinsic carrier concentration results in a shift of the Fermi level toward mid-bandgap at elevated temperatures. This produces a shift in devices characteristics as a function of temperature. By increasing the doping concentration higher operating temperatures can be achieved. This technique was used to fabricate low power analog and digital devices in silicon with junction operating temperatures in excess of 300 C. Additional temperature effects include increased p-n junction leakage with increasing temperature, resulting in increased resistivity. The temperature dependency of physical properties results in variations in device characteristics. These must be quantified and understood in order to develop extended temperature range operation.

  19. Performance issues for iterative solvers in device simulation

    NASA Technical Reports Server (NTRS)

    Fan, Qing; Forsyth, P. A.; Mcmacken, J. R. F.; Tang, Wei-Pai

    1994-01-01

    Due to memory limitations, iterative methods have become the method of choice for large scale semiconductor device simulation. However, it is well known that these methods still suffer from reliability problems. The linear systems which appear in numerical simulation of semiconductor devices are notoriously ill-conditioned. In order to produce robust algorithms for practical problems, careful attention must be given to many implementation issues. This paper concentrates on strategies for developing robust preconditioners. In addition, effective data structures and convergence check issues are also discussed. These algorithms are compared with a standard direct sparse matrix solver on a variety of problems.

  20. An information-measuring system for evaluating performance parameters of lighting devices

    NASA Astrophysics Data System (ADS)

    Abulkhanov, Stanislav R.; Kharitonov, Sergey I.

    2016-04-01

    We propose the design of an information-measuring system for evaluating performance parameters of lighting devices. The system comprises four basic components: a software-hardware complex for designing lighting devices, an emulator of natural and technogeneous effects on an optical surface, an optical surface condition analyzer, and a lighting-device laboratory test unit. With this system, the duration of optical device certification tests can be reduced by several orders of magnitude when compared to full-scale tests.

  1. Silicon device performance measurements to support temperature range enhancement

    NASA Technical Reports Server (NTRS)

    Bromstead, James; Weir, Bennett; Nelms, R. Mark; Johnson, R. Wayne; Askew, Ray

    1994-01-01

    Silicon based power devices can be used at 200 C. The device measurements made during this program show a predictable shift in device parameters with increasing temperature. No catastrophic or abrupt changes occurred in the parameters over the temperature range. As expected, the most dramatic change was the increase in leakage currents with increasing temperature. At 200 C the leakage current was in the milliAmp range but was still several orders of magnitude lower than the on-state current capabilities of the devices under test. This increase must be considered in the design of circuits using power transistors at elevated temperature. Three circuit topologies have been prototyped using MOSFET's and IGBT's. The circuits were designed using zero current or zero voltage switching techniques to eliminate or minimize hard switching of the power transistors. These circuits have functioned properly over the temperature range. One thousand hour life data have been collected for two power supplies with no failures and no significant change in operating efficiency. While additional reliability testing should be conducted, the feasibility of designing soft switched circuits for operation at 200 C has been successfully demonstrated.

  2. Interfacial Modification for Enhanced Performance of OPV Devices

    NASA Astrophysics Data System (ADS)

    Ginley, David

    2010-03-01

    Organic Photovoltaics (OPV) represent a potentially low cost, scalable approach to produce renewable energy at near the Terrawatt scale. Their low temperature solution based processing potentially leads to cost/per watt well below 0.50. Over the last year OPV has seen a rapid evolution in efficiency to a now certified 7.9% for Solarmer. As important module efficiencies are nearing 4% supporting scalability. There is now a pretty clear pathway for developing acceptors and donors so as to achieve 10% or greater. One of the key questions remaining is that of the stability of OPV devices and the potential for their lifetime to be sufficient for commercial viability. Critical to this is both the intrinsic stability of the donor/acceptor phase separated mixture and the stability of the interfaces especially those between the inorganic and organic phases. We will report on a number of recent studies beginning to look at the mechanisms of degradation in OPV device structures and on their potential resolution through new materials, new device configurations and enhanced encapsulation. Current data indicates that there is no inherent instability in the bulk heterojunction and that solving the interfacial issues may lead to devices of sufficient stability for commercial viability.[4pt] In collaboration with Joseph Berry, Matthew Lloyd, Matt White, Nikos Kopidakis, Xerxes Steires, Ajaya Sigdel, Nicodemus Widjonarko, Matthew Reese and Sean Shaheen, and Dana Olsen, National Renewable Energy Laboratory.

  3. Effect of relative humidity on crystal growth, device performance and hysteresis in planar heterojunction perovskite solar cells.

    PubMed

    Gangishetty, Mahesh K; Scott, Robert W J; Kelly, Timothy L

    2016-03-17

    Due to the hygroscopic nature of organolead halide perovskites, humidity is one of the most important factors affecting the efficiency and longevity of perovskite solar cells. Although humidity has a long term detrimental effect on device performance, it also plays a key role during the initial growth of perovskite crystals. Here we demonstrate that atmospheric relative humidity (RH) plays a key role during the formation of perovskite thin films via the sequential deposition technique. Our results indicate that the RH has a substantial impact on the crystallization process, and hence on device performance. SEM and pXRD analysis show an increase in crystallite size with increasing humidity. At low RH, the formation of small cubic crystallites with large gaps between them is observed. The presence of these voids adversely affects device performance and leads to substantial hysteresis in the device. At higher RH, the perovskite crystals are larger in size, with better connectivity between the crystallites. This produced efficient planar heterojunction solar cells with low hysteresis. By careful control of the RH during the cell fabrication process, efficiencies of up to 12.2% are reached using P3HT as the hole-transport material. PMID:26411485

  4. A Device for Performing Automated Balloon Catheter Inflation Ischemia Studies

    PubMed Central

    Leavesley, Silas J.; Ledkins, Whitley; Rocic, Petra

    2014-01-01

    Coronary collateral growth (arteriogenesis) is a physiological adaptive response to transient and repetitive occlusion of major coronary arteries in which small arterioles (native collaterals) with minimal to no blood flow remodel into larger conduit arteries capable of supplying adequate perfusion to tissue distal to the site of occlusion. The ability to reliably and reproducibly mimic transient, repetitive coronary artery occlusion (ischemia) in animal models is critical to the development of therapies to restore coronary collateral development in type II diabetes and the metabolic syndrome. Current animal models for repetitive coronary artery occlusion implement a pneumatic occluder (balloon) that is secured onto the surface of the heart with the suture, which is inflated manually, via a catheter connected to syringe, to effect occlusion of the left anterior descending coronary artery (LAD). This method, although effective, presents complications in terms of reproducibility and practicality. To address these limitations, we have designed a device for automated, transient inflation of balloon catheters in coronary artery occlusion models. This device allows repeated, consistent inflation (to either specified pressure or volume) and the capability for implementing very complex, month-long protocols. This system has significantly increased the reproducibility of coronary collateral growth studies in our laboratory, resulting in a significant decrease in the numbers of animals needed to complete each study while relieving laboratory personnel from the burden of extra working hours and enabling us to continue studies over periods when we previously could not. In this paper, we present all details necessary for construction and operation of the inflator. In addition, all of the components for this device are commercially available and economical (Table S1). It is our hope that the adoption of automated balloon catheter inflation protocols will improve the experimental

  5. Silicon device performance measurements to support temperature range enhancement

    NASA Technical Reports Server (NTRS)

    Johnson, R. Wayne; Askew, Ray; Bromstead, James; Weir, Bennett

    1991-01-01

    The results of the NPN bipolar transistor (BJT) (2N6023) breakdown voltage measurements were analyzed. Switching measurements were made on the NPN BJT, the insulated gate bipolar transistor (IGBT) (TA9796) and the N-channel metal oxide semiconductor field effect transistor (MOSFET) (RFH75N05E). Efforts were also made to build a H-bridge inverter. Also discussed are the plans that have been made to do life testing on the devices, to build an inductive switching test circuit and to build a dc/dc switched mode converter.

  6. Performance of the KHI FEL device at FEL-SUT

    NASA Astrophysics Data System (ADS)

    Yokoyama, M.; Oda, F.; Nomaru, K.; Koike, H.; Sobajima, M.; Miura, H.; Kawai, M.; Kuroda, H.

    2002-05-01

    FEL lasing with the saturated power in the wavelength of 4-16 μm was achieved by using the KHI (Kawasaki Heavy Industries, Ltd.) FEL device. The macro-pulse length of the electron beam was improved by using the LaB 6 cathode instead of the dispenser cathode as a cathode of the OCS RF-gun. The improvement yielded the saturated FEL power with the macro-pulse length of 0.5-1.5 μs. The FEL energy was 2-40 mJ. The measured FEL output powers were in agreement with the values which were taken into account Piovella's theory.

  7. An Analysis of Team Composition as It Affects Simulation Performance.

    ERIC Educational Resources Information Center

    Krishnakumar, Parameswar; Chisholm, Thomas Alexander

    This study investigated the extent to which sex composition and average team academic achievement of student simulation teams affect team effectiveness. Seventy-four students in two sections of a marketing principles class were divided into 20 teams to test their decision-making skills. For 10 weeks, each team operated a simulated supermarket…

  8. Impact of Electronic Device Use in Class on Pharmacy Students’ Academic Performance

    PubMed Central

    Johnson, Heather L.; Wrobel, Mark J.

    2012-01-01

    Objectives. To evaluate and assess the impact of pharmacy students’ electronic device (e-device) use during a lecture-based pharmacotherapeutics sequence. Methods. A validated survey instrument to assess e-device use was e-mailed to 238 second- (P2) and third-year (P3) pharmacy students. Grades were reviewed retrospectively and correlated with e-device use to determine its impact on academic performance. Results. Of 140 responding students (59% response rate), 106 reported using e-devices during class for course-related (91.5%) and non-course-related (81.1%) activities. When P2 and P3 students were combined, e-device use was not associated with academic performance (p = 0.70). Academic performance was not impacted among P3 students (p = 0.86), but P2 students performed better academically if they refrained from using e-devices during class (mean grade = 88.5% vs. 83.3%; p=0.019). Conclusions. The impact of e-device use on overall academic performance was negligible. Use of e-devices by students enrolled in their first pharmacotherapeutics course may negatively impact academics. PMID:23193331

  9. Comparison of the mechanical performance of trochanteric fixation devices.

    PubMed

    Hersh, C K; Williams, R P; Trick, L W; Lanctot, D; Athanasiou, K

    1996-08-01

    The transtrochanteric surgical approach to the hip is commonly used, especially for revision hip surgery. Failure of the trochanter to heal can lead to hardware failure, persistent pain, and limp. Rigid internal fixation is needed in this approach to achieve an adequate rate of healing. Newer cable and cable grip systems have been designed to improve trochanteric fixation, but have not been compared to the older Charnley wire fixation techniques. In this study, an in vitro mechanical method previously used to test wire fixation methods was used to compare wire, cable, and cable grip fixation methods. A quasistatic mechanical distraction device was used to compare structural stiffness, load to clinical failure, energy to clinical failure, and maximum load resisted by the fixation devices. The cable grip system was found to be stiffer, to resist a larger load to mechanical failure at 1-cm displacement, and to absorb a greater amount of energy to clinical failure when compared with the other systems. These data suggest that use of the cable grip fixation method should result in improved clinical success compared with the Charnley wire technique. PMID:8769467

  10. Performance of a Portable Sleep Monitoring Device in Individuals with High Versus Low Sleep Efficiency

    PubMed Central

    Markwald, Rachel R.; Bessman, Sara C.; Reini, Seth A.; Drummond, Sean P.A.

    2016-01-01

    Study Objectives: Portable and automated sleep monitoring technology is becoming widely available to consumers, and one wireless system (WS) has recently surfaced as a research tool for sleep and sleep staging assessment outside the hospital/laboratory; however, previous research findings indicate low sensitivity for wakefulness detection. Because difficulty discriminating between wake and sleep is likely to affect staging performance, we sought to further evaluate the WS by comparing it to the gold-standard polysomnography (PSG) and actigraphy (ACT) for overall sleep/wakefulness detection and sleep staging, within high and low sleep efficiency sleepers. Methods: Twenty-nine healthy adults (eight females) underwent concurrent WS, PSG, and ACT assessment in an overnight laboratory study. Epoch-by-epoch agreement was determined by comparing sleep/wakefulness decisions between the WS to both PSG and ACT, and for detection of light, deep, and rapid eye movement (REM) sleep stages between the WS and PSG. Results: Sensitivity for wakefulness was low (40%), and an overestimation of total sleep time and underestimation of wake after sleep onset was observed. Prevalence and bias adjusted kappa statistic indicated moderate-to-high agreement between the WS and PSG for sleep staging. However, upon further inspection, WS performance varied by sleep efficiency, with the best performance during high sleep efficiency. Conclusions: The benefit of the WS as a sleep monitoring device over ACT is the ability to assess sleep stages, and our findings suggest this benefit is only realized within high sleep efficiency. Care should be taken to collect data under conditions where this is expected. Citation: Markwald RR, Bessman SC, Reini SA, Drummond SP. Performance of a portable sleep monitoring device in individuals with high versus low sleep efficiency. J Clin Sleep Med 2016;12(1):95–103. PMID:26285110

  11. Factors Affecting the Performance of Public Schools in Lebanon

    ERIC Educational Resources Information Center

    Mattar, Dorine M.

    2012-01-01

    By sampling extreme cases (five high-performing schools and five low-performing ones), the researcher revealed the differences in the teachers' motivation (Mattar, 2010) as well as the extent to which Principals adopted the instructional leadership style (Mattar, 2012) in the two sets of schools. Here, she looked for additional issues, within the…

  12. Learners' Metalinguistic and Affective Performance in Blogging to Write

    ERIC Educational Resources Information Center

    Chen, Ping-Ju

    2016-01-01

    The documentation of the benefits of blog use in foreign language education has proliferated since 2006. In the field of blogging to write, most studies focus on learners' linguistic performance and perceptions. To provide an analysis of learners' writing performance by using blogs, in addition to the often-researched areas, this study examines…

  13. Young Children's Knowledge About Effects of Affect on Performance.

    ERIC Educational Resources Information Center

    Pierce, Jean W.

    1985-01-01

    Addresses the issue of whether preschoolers are aware of the connection between their emotions, their performance on a task of eye-hand coordination, and their evaluation of the task and their performance. Results indicate a developmental trend that children's predictions conform more to mood congruity theory as they grow older. (Author/DST)

  14. Growth in body size affects rotational performance in women's gymnastics.

    PubMed

    Ackland, Timothy; Elliott, Bruce; Richards, Joanne

    2003-07-01

    National and state representative female gymnasts (n = 37), aged initially between 10 and 12 years, completed a mixed longitudinal study over 3.3 years, to investigate the effect of body size on gymnastic performance. Subjects were tested at four-monthly intervals on a battery of measures including structural growth, strength and gymnastic performance. The group were divided into 'high growers' and 'low growers' based on height (> 18 cm or < 14 cm/37 months, respectively) and body mass (> 15 kg or < 12 kg/37 months, respectively) for comparative purposes. Development of gymnastic performance was assessed through generic skills (front and back rotations, a twisting jump and a V-sit action) and a vertical jump for maximum height. The results show that the smaller gymnast, with a high strength to mass ratio, has greater potential for performing skills involving whole-body rotations. Larger gymnasts, while able to produce more power and greater angular momentum, could not match the performance of the smaller ones. The magnitude of growth experienced by the gymnast over this period has a varying effect on performance. While some activities were greatly influenced by rapid increases in whole-body moment of inertia (e.g. back rotation), performance on others like the front rotation and vertical jump, appeared partly immune to the physical and mechanical changes associated with growth. PMID:14737925

  15. Wintering performance and how it affects carcass quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Environmental variation undoubtedly can have the most significant impact on livestock performance in forage based production systems. Fluctuations in temperature and precipitation influence herbage production and quality, maintenance requirements and intake. Producers of “forage system” products h...

  16. Digital Devices, Distraction and Student Performance - Does Cell Phone Use Reduce Learning?

    NASA Astrophysics Data System (ADS)

    Duncan, Douglas K.; Hoekstra, A. R.; Wilcox, B. R.

    2012-01-01

    The recent increase in the use of digital devices such as laptop computers, iPads and web-enabled cell phones has generated concern about how technologies affect student performance. Combining observation, survey, and interview data, this research assesses the effects of technology use for student attitudes and learning. Data were gathered in eight introductory science courses at one large public university in 2010-2011. Results show a significant negative correlation between in-class cell phone use and overall course grades, corresponding to a drop of 0.36 ± 0.08 on a 4-point scale where 4.0 = A. These findings are consistent with recent research[1] suggesting students cannot multi-task nearly as effectively as they think they can. While 75% of students reported regular cell phone use, observation data suggests undergraduates typically under-report the frequency of in-class digital device use. [1] Ophir, E., Nass, C. and A.D. Wagner. 2009. "Cognitive Control in Media Multi-Taskers.” Proceedings of the National Academy of Sciences, 106: 15583-15587.

  17. Knowledge system and method for simulating chemical controlled release device performance

    DOEpatents

    Cowan, Christina E.; Van Voris, Peter; Streile, Gary P.; Cataldo, Dominic A.; Burton, Frederick G.

    1991-01-01

    A knowledge system for simulating the performance of a controlled release device is provided. The system includes an input device through which the user selectively inputs one or more data parameters. The data parameters comprise first parameters including device parameters, media parameters, active chemical parameters and device release rate; and second parameters including the minimum effective inhibition zone of the device and the effective lifetime of the device. The system also includes a judgemental knowledge base which includes logic for 1) determining at least one of the second parameters from the release rate and the first parameters and 2) determining at least one of the first parameters from the other of the first parameters and the second parameters. The system further includes a device for displaying the results of the determinations to the user.

  18. In-Field Performance Testing of Stormwater Treatment Devices

    EPA Science Inventory

    The Environmental Technology Verification (ETV) Program was created by EPA’s Office of Research and Development to facilitate the deployment of innovative or improved environmental technologies through performance verification and dissemination of information. The program’s goal ...

  19. Emissions from premixed charge compression ignition (PCCI) combustion and affect on emission control devices

    SciTech Connect

    Parks, II, James E; Kass, Michael D; Huff, Shean P; Barone, Teresa L; Lewis Sr, Samuel Arthur; Prikhodko, Vitaly Y; Storey, John Morse

    2010-01-01

    A light-duty diesel engine has been operated in advanced combustion modes known generally as premixed charge compression ignition (PCCI). The emissions have been characterized for several load and speed combinations. Fewer NO{sub x} and particulate matter (PM) emissions are produced by PCCI, but higher CO and hydrocarbon (HC) emissions result. In addition, the nature of the PM differs from conventional combustion; the PM is smaller and has a much higher soluble organic fraction (SOF) content (68% vs. 30% for conventional combustion). Three catalyst technologies were studied to determine the affects of HECC on catalyst performance; the technologies were a lean NO{sub x} trap (LNT), diesel oxidation catalyst (DOC), and diesel particulate filter (DPF). The LNT benefited greatly from the reduced NO{sub x} emissions associated with PCCI. NO{sub x} capacity requirements are reduced as well as overall tailpipe NO{sub x} levels particularly at low load and temperature conditions where regeneration of the LNT is difficult. The DOC performance requirements for PCCI are more stringent due to the higher CO and HC emissions; however, the DOC was effective at controlling the higher CO and HC emissions at conditions above the light-off temperature. Below light-off, CO and HC emissions are problematic. The study of DPF technology focused on the fuel penalties associated with DPF regeneration or 'desoot' due to the different PM loading rates from PCCI vs. conventional combustion. Less frequent desoot events were required from the lower PM from PCCI and, when used in conjunction with an LNT, the lower PM from less frequent LNT regeneration. The lower desoot frequency leads a {approx}3% fuel penalty for a mixture of PCCI and conventional loads vs. {approx}4% for conventional only combustion.

  20. When children affect parents: Children's academic performance and parental investment.

    PubMed

    Yurk Quadlin, Natasha

    2015-07-01

    Sociologists have extensively documented the ways that parent resources predict children's achievement. However, less is known about whether and how children's academic performance shapes parental investment behaviors. I use data from the Early Childhood Longitudinal Study-Kindergarten Cohort (ECLS-K) and longitudinal fixed effects models to examine how changes in teacher assessments are related to changes in the conferral of various parent resources. Overall, I find that the relationship between achievement and investment varies based on the directionality in children's achievement and the type of resource at hand. Children whose performance improves receive a broad range of enrichment resources, while declines in performance are met with corrective educational resources. Results are largely consistent whether language or math assessments are used to predict investment, and also among children whose achievement does not change over time. I discuss these patterns, along with implications for the use of parent resources in education and family research. PMID:26004488

  1. Productive high-performance software for OpenCL devices

    NASA Astrophysics Data System (ADS)

    Melonakos, John M.; Yalamanchili, Pavan; McClanahan, Chris; Arshad, Umar; Landes, Michael; Jamboti, Shivapriya; Joshi, Abhijit; Mohammed, Shehzan; Spafford, Kyle; Venugopalakrishnan, Vishwanath; Malcolm, James

    2013-05-01

    Over the last three decades, CPUs have continued to produce large performance improvements from one generation to the next. However, CPUs have recently hit a performance wall and need parallel computing to move forward. Parallel computing over the next decade will become increasingly defined by heterogeneous computing, involving the use of accelerators in addition to CPUs to get computational tasks done. In order to use an accelerator, software changes must be made. Regular x86-based compilers cannot compile code to run on accelerators without these needed changes. The amount of software change required varies depending upon the availability of and reliance upon software tools that increase performance and productivity. Writing software that leverages the best parallel computing hardware, adapts well to the rapid pace of hardware updates, and minimizes developer muscle is the industry's goal. OpenCL is the standard around which developers are able to achieve parallel performance. OpenCL itself is too difficult to program to receive general adoptions, but productive high-performing software libraries are becoming increasingly popular and capable in delivering lasting value to user applications.

  2. High-Performance Flexible Organic Nano-Floating Gate Memory Devices Functionalized with Cobalt Ferrite Nanoparticles.

    PubMed

    Jung, Ji Hyung; Kim, Sunghwan; Kim, Hyeonjung; Park, Jongnam; Oh, Joon Hak

    2015-10-01

    Nano-floating gate memory (NFGM) devices are transistor-type memory devices that use nanostructured materials as charge trap sites. They have recently attracted a great deal of attention due to their excellent performance, capability for multilevel programming, and suitability as platforms for integrated circuits. Herein, novel NFGM devices have been fabricated using semiconducting cobalt ferrite (CoFe2O4) nanoparticles (NPs) as charge trap sites and pentacene as a p-type semiconductor. Monodisperse CoFe2O4 NPs with different diameters have been synthesized by thermal decomposition and embedded in NFGM devices. The particle size effects on the memory performance have been investigated in terms of energy levels and particle-particle interactions. CoFe2O4 NP-based memory devices exhibit a large memory window (≈73.84 V), a high read current on/off ratio (read I(on)/I(off)) of ≈2.98 × 10(3), and excellent data retention. Fast switching behaviors are observed due to the exceptional charge trapping/release capability of CoFe2O4 NPs surrounded by the oleate layer, which acts as an alternative tunneling dielectric layer and simplifies the device fabrication process. Furthermore, the NFGM devices show excellent thermal stability, and flexible memory devices fabricated on plastic substrates exhibit remarkable mechanical and electrical stability. This study demonstrates a viable means of fabricating highly flexible, high-performance organic memory devices. PMID:26153227

  3. How Motivation Affects Academic Performance: A Structural Equation Modelling Analysis

    ERIC Educational Resources Information Center

    Kusurkar, R. A.; Ten Cate, Th. J.; Vos, C. M. P.; Westers, P.; Croiset, G.

    2013-01-01

    Few studies in medical education have studied effect of quality of motivation on performance. Self-Determination Theory based on quality of motivation differentiates between Autonomous Motivation (AM) that originates within an individual and Controlled Motivation (CM) that originates from external sources. To determine whether Relative Autonomous…

  4. Factors Affecting School District Performance Scores in Louisiana

    ERIC Educational Resources Information Center

    Harrison, Ronnie

    2010-01-01

    The purpose of this study was to investigate the relationship between District Performance Scores (DPS) in Louisiana and (a) socio-economic status of students, (b) academic achievement using average ACT scores, (c) percentage of certified teachers, (d) district class size, (e) per pupil expenditure, and (f) percentage of minority students in…

  5. Does Participative Decision Making Affect Lecturer Performance in Higher Education?

    ERIC Educational Resources Information Center

    Sukirno, D. S.; Siengthai, Sununta

    2011-01-01

    Purpose: The relationship between participation and job performance has captured the interest of not only business researchers but also education researchers. However, the topic has not gained significant attention in the educational management research arena. The purpose of this paper is to empirically examine the impact of participation in…

  6. Teacher Dispositions Affecting Self-Esteem and Student Performance

    ERIC Educational Resources Information Center

    Helm, Carroll

    2007-01-01

    Research supports several factors related to student success. Darling-Hammond (2000) indicated that the quality of teachers, as measured by whether the teachers were fully certified and had a major in their teaching field, was related to student performance. Measures of teacher preparation and certification were the strongest predictors of student…

  7. Early Teacher Expectations Disproportionately Affect Poor Children's High School Performance

    ERIC Educational Resources Information Center

    Sorhagen, Nicole S.

    2013-01-01

    This research used prospective longitudinal data to examine the associations between first-grade teachers' over- and underestimation of their students' math abilities, basic reading abilities, and language skills and the students' high school academic performance, with special attention to the subject area and moderating effects of student…

  8. Social Process Variables Affecting Reading Performance in Delayed Readers.

    ERIC Educational Resources Information Center

    Lorton, Mary; Kukuk, Cristopher

    A study was conducted to determine the relationship between fourteen social process variables (relating to perinatal events, early language patterns, parental/home environment, and child behavior patterns) and the reading performance of retarded readers. The subjects were 180 children, aged seven through fifteen, randomly selected from among…

  9. FinFET Doping; Material Science, Metrology, and Process Modeling Studies for Optimized Device Performance

    SciTech Connect

    Duffy, R.; Shayesteh, M.

    2011-01-07

    In this review paper the challenges that face doping optimization in 3-dimensional (3D) thin-body silicon devices will be discussed, within the context of material science studies, metrology methodologies, process modeling insight, ultimately leading to optimized device performance. The focus will be on ion implantation at the method to introduce the dopants to the target material.

  10. Effects of Surface Composition on CdTe/CdS Device Performance

    SciTech Connect

    Levi, D.; Albin, D.; King, D.

    2000-01-01

    The atomic composition of the back surface of the CdTe layer in a CdTe/CdS photovoltiac (PV) device has a significant influence on the quality of the electrical contact to this layer. This paper reports the results of a systematic study that correlates the composition of the back surface with pre-contact processing and device performance.

  11. An Evaluation of Performance Characteristics of Primary Display Devices.

    PubMed

    Ekpo, Ernest U; McEntee, Mark F

    2016-04-01

    The aim of this study was to complete a full evaluation of the new EIZO RX850 liquid crystal display and compare it to two currently used medical displays in Australia (EIZO GS510 and Barco MDCG 5121). The American Association of Physicists in Medicine (AAPM) Task Group 18 Quality Control test pattern was used to assess the performance of three high-resolution primary medical displays: EIZO RX850, EIZO GS510, and Barco MDCG 5121. A Konica Minolta spectroradiometer (CS-2000) was used to assess luminance response, non-uniformity, veiling glare, and color uniformity. Qualitative evaluation of noise was also performed. Seven breast lesions were displayed on each monitor and photographed with a calibrated 5.5-MP Olympus E-1 digital SLR camera. ImageJ software was used to sample pixel information from each lesion and surrounding background to calculate their conspicuity index on each of the displays. All monitor fulfilled all AAPM acceptance criteria. The performance characteristics for EIZO RX850, Barco MDCG 5121, and EIZO GS510 respectively were as follows: maximum luminance (490, 500.5, and 413 cd/m(2)), minimum luminance (0.724, 1.170, and 0.92 cd/m(2)), contrast ratio (675:1, 428:1, 449:1), just-noticeable difference index (635, 622, 609), non-uniformity (20, 5.92, and 8.5 %), veiling glare (GR = 2465.6, 720.4, 1249.8), and color uniformity (Δu'v' = +0.003, +0.002, +0.002). All monitors demonstrated low noise levels. The conspicuity index (χ) of the lesions was slightly higher in the EIZO RX850 display. All medical displays fulfilled AAPM performance criteria, and performance characteristics of EIZO RX850 are equal to or better than those of the Barco MDCG 5121 and EIZO GS510 displays. PMID:26438424

  12. Scales affect performance of Monarch butterfly forewings in autorotational flight

    NASA Astrophysics Data System (ADS)

    Demko, Anya; Lang, Amy

    2012-11-01

    Butterfly wings are characterized by rows of scales (approximately 100 microns in length) that create a shingle-like pattern of cavities over the entire surface. It is hypothesized that these cavities influence the airflow around the wing and increase aerodynamic performance. A forewing of the Monarch butterfly (Danus plexippus) naturally undergoes autorotational flight in the laminar regime. Autorotational flight is an accurate representation of insect flight because the rotation induces a velocity gradient similar to that found over a flapping wing. Drop test flights of 22 forewings before and after scale removal were recorded with a high-speed camera and flight behavior was quantified. It was found that removing the scales increased the descent speed and decreased the descent factor, a measure of aerodynamic efficacy, suggesting that scales increased the performance of the forewings. Funded by NSF REU Grant 1062611.

  13. Luminance controlled pupil size affects Landolt C task performance. Revision

    SciTech Connect

    Berman, S.M.; Fein, G.; Jewett, D.L.; Ashford, F.

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m{sup 2} and 73 cd/m{sup 2}. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  14. Luminance controlled pupil size affects Landolt C task performance

    SciTech Connect

    Berman, S.M. ); Fein, G. ); Jewett, D.L.; Ashford, F. )

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m[sup 2] and 73 cd/m[sup 2]. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  15. Factors That Affect Academic Performance Among Pharmacy Students

    PubMed Central

    Sansgiry, Sujit S.; Bhosle, Monali; Sail, Kavita

    2006-01-01

    Objective The objective of this study was to examine factors such as academic competence, test competence, time management, strategic studying, and test anxiety, and identify whether these factors could distinguish differences among students, based on academic performance and enrollment in the experiential program. Methods A cross-sectional study design utilizing questionnaires measuring previously validated constructs was used to evaluate the effect of these factors on students with low and high cumulative grade point averages (GPAs). Pharmacy students (N = 198) enrolled at the University of Houston participated in the study. Results Academic performance was significantly associated with factors such as academic competence and test competence. Students with a cumulative GPA of 3.0 or greater significantly differed in their level of test competence than those with a GPA of less than 3.0. Students enrolled in their experiential year differed from students enrolled in their second year of curriculum on factors such as test anxiety, academic competence, test competence, and time management skills. Conclusion Test competence was an important factor to distinguish students with low vs. high academic performance. Factors such as academic competence, test competence, test anxiety and time management improve as students' progress in their experiential year. PMID:17149433

  16. Positive affective tone and team performance: The moderating role of collective emotional skills.

    PubMed

    Collins, Amy L; Jordan, Peter J; Lawrence, Sandra A; Troth, Ashlea C

    2016-01-01

    Research on affect as a group-level phenomenon has shown that over time, individual members within a group become highly similar in their affect (i.e., members experience and display similar emotions and moods), and often become similar enough that the aggregation of individuals' affect can meaningfully represent the "affective tone" of the group. It is generally assumed that a more positive affective tone will lead to better team performance. We challenge the conclusion that positive affective tone is always good for team performance, suggesting that the relationship between positive affective tone and team performance is subject to moderating influences. Across two studies, we demonstrate that the self-reported collective emotional skills of team members play a crucial role in determining whether positive affective tone is beneficial or detrimental to team performance. Implications for theory and practice are discussed. PMID:26208085

  17. Regression analysis of technical parameters affecting nuclear power plant performances

    SciTech Connect

    Ghazy, R.; Ricotti, M. E.; Trueco, P.

    2012-07-01

    Since the 80's many studies have been conducted in order to explicate good and bad performances of commercial nuclear power plants (NPPs), but yet no defined correlation has been found out to be totally representative of plant operational experience. In early works, data availability and the number of operating power stations were both limited; therefore, results showed that specific technical characteristics of NPPs were supposed to be the main causal factors for successful plant operation. Although these aspects keep on assuming a significant role, later studies and observations showed that other factors concerning management and organization of the plant could instead be predominant comparing utilities operational and economic results. Utility quality, in a word, can be used to summarize all the managerial and operational aspects that seem to be effective in determining plant performance. In this paper operational data of a consistent sample of commercial nuclear power stations, out of the total 433 operating NPPs, are analyzed, mainly focusing on the last decade operational experience. The sample consists of PWR and BWR technology, operated by utilities located in different countries, including U.S. (Japan)) (France)) (Germany)) and Finland. Multivariate regression is performed using Unit Capability Factor (UCF) as the dependent variable; this factor reflects indeed the effectiveness of plant programs and practices in maximizing the available electrical generation and consequently provides an overall indication of how well plants are operated and maintained. Aspects that may not be real causal factors but which can have a consistent impact on the UCF, as technology design, supplier, size and age, are included in the analysis as independent variables. (authors)

  18. Malaria Rapid Diagnostic Devices: Performance Characteristics of the ParaSight F Device Determined in a Multisite Field Study

    PubMed Central

    Forney, J. Russ; Magill, Alan J.; Wongsrichanalai, Chansuda; Sirichaisinthop, Jeeraphat; Bautista, Christian T.; Heppner, D. Gray; Miller, R. Scott; Ockenhouse, Christian F.; Gubanov, Alex; Shafer, Robyn; DeWitt, Caroline Cady; Quino-Ascurra, Higinio A.; Kester, Kent E.; Kain, Kevin C.; Walsh, Douglas S.; Ballou, W. Ripley; Gasser, Robert A.

    2001-01-01

    Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/μl), 87% (501 to 1,000/μl), 98% (1,001 to 5,000/μl), and 98% (>5,000/μl). Device specificity was 86%. PMID:11474008

  19. Characterization of titanium dioxide: Factors affecting photocatalytic performance

    SciTech Connect

    Presley, R.W.

    1995-06-01

    Titanium dioxide is being evaluated as a photocatalyst in the destruction of contaminants in aqueous waste streams. Commercial samples of TiO{sub 2} powder have been obtained for base line studies of the photocatalytic destruction of salicylic acid standards. These commercial samples have been prepared by flame hydrolysis and aerosol or spray pyrolysis. Additional samples of TiO{sub 2} have been prepared in house by precipitation from TiCl{sub 4} in aqueous solution, some with the addition of dopants. X-ray powder diffraction data analysis indicates the predominate phase of these commercial and prepared powders to be anatase. A minor amount of the rutile crystalline phase of TiO{sub 2} was observed at various levels in some of these catalysts. The broadness of the x-ray diffraction bands varied among the samples analyzed and indicated the primary particle size to be within the 500 to 1,000 angstrom range with the product produced in house having the smallest crystallite size. Experiments were then performed to assess the photocatalytic performance of these various types of catalyst in the destruction of 30 ppm salicylic acid in deionized water.

  20. 78 FR 58316 - Complex Issues in Developing Medical Devices for Pediatric Patients Affected by Rare Diseases...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-23

    ... inappropriate for pediatric use due to a variety of factors, including patient size, growth, and development, or... practice trends of medical devices in rare disease pediatric populations. For example, how much off-label... pediatric populations? B. HUD/HDE 1. Is there any confusion about the designation process for HUDs or...

  1. Factors affecting the performance of large-aperture microphone arrays.

    PubMed

    Silverman, Harvey F; Patterson, William R; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m x 8 m x 3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment. PMID:12051434

  2. Factors affecting the performance of large-aperture microphone arrays

    NASA Astrophysics Data System (ADS)

    Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  3. Performance Modeling of Network-Attached Storage Device Based Hierarchical Mass Storage Systems

    NASA Technical Reports Server (NTRS)

    Menasce, Daniel A.; Pentakalos, Odysseas I.

    1995-01-01

    Network attached storage devices improve I/O performance by separating control and data paths and eliminating host intervention during the data transfer phase. Devices are attached to both a high speed network for data transfer and to a slower network for control messages. Hierarchical mass storage systems use disks to cache the most recently used files and a combination of robotic and manually mounted tapes to store the bulk of the files in the file system. This paper shows how queuing network models can be used to assess the performance of hierarchical mass storage systems that use network attached storage devices as opposed to host attached storage devices. Simulation was used to validate the model. The analytic model presented here can be used, among other things, to evaluate the protocols involved in 1/0 over network attached devices.

  4. Nanosoldering carbon nanotube junctions by local chemical vapor deposition for improved device performance.

    PubMed

    Do, Jae-Won; Estrada, David; Xie, Xu; Chang, Noel N; Mallek, Justin; Girolami, Gregory S; Rogers, John A; Pop, Eric; Lyding, Joseph W

    2013-01-01

    The performance of carbon nanotube network (CNN) devices is usually limited by the high resistance of individual nanotube junctions (NJs). We present a novel method to reduce this resistance through a nanoscale chemical vapor deposition (CVD) process. By passing current through the devices in the presence of a gaseous CVD precursor, localized nanoscale Joule heating induced at the NJs stimulates the selective and self-limiting deposition of metallic nanosolder. The effectiveness of this nanosoldering process depends on the work function of the deposited metal (here Pd or HfB2), and it can improve the on/off current ratio of a CNN device by nearly an order of magnitude. This nanosoldering technique could also be applied to other device types where nanoscale resistance components limit overall device performance. PMID:24215439

  5. Performance improvements of symmetry-breaking reflector structures in nonimaging devices

    DOEpatents

    Winston, Roland

    2004-01-13

    A structure and method for providing a broken symmetry reflector structure for a solar concentrator device. The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quantity, referred to as the translational skew invariant, is conserved in rotationally symmetric optical systems. Performance limits for translationally symmetric nonimaging optical devices are derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. A numerically optimized non-tracking solar concentrator utilizing symmetry-breaking reflector structures can overcome the performance limits associated with translational symmetry.

  6. Effects of traps and polarization charges on device performance of AlGaN/GaN high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Hussein, A. SH.; Ghazai, Alaa J.; Salman, Emad A.; Hassan, Z.

    2013-11-01

    This paper presents the simulated electrical characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) by using ISE TCAD software. The effects of interface traps, bulk traps and polarization charges are investigated. It was observed that the role and dynamic of traps affect the device performance which requires a precondition to calculate the DC characteristics that are in agreement with the experimental data. On the other hand, polarization charges lead to quantum confinement of the electrons in the channel and form two-dimensional electron gas. The electron quantization leads to increasing the drain current and shift in the threshold voltage. The device performance can be improved by optimizing the fixed interface charge and thus reducing the bulk traps to enhance the DC characteristics.

  7. Noise Affects Performance on the Montreal Cognitive Assessment.

    PubMed

    Dupuis, Kate; Marchuk, Veronica; Pichora-Fuller, M Kathleen

    2016-09-01

    We investigated the effect of background noise on performance on the Montreal Cognitive Assessment (MoCA). Two groups of older adults (one with clinically normal hearing, one with hearing loss) and a younger adult group with clinically normal hearing were administered two versions of the MoCA under headphones in low and high levels of background noise. Intensity levels used to present the test were customized based on the hearing abilities of participants with hearing loss to yield a uniform level of difficulty across listeners in the high-level noise condition. Both older groups had poorer MoCA scores in noise than the younger group. Importantly, all participants had poorer MoCA scores in the high-noise (M = 22.7/30) compared to the low-noise condition (M = 25.7/30, p < .001). Results suggest that background noise in the test environment should be considered when cognitive tests are conducted and results interpreted, especially when testing older adults. PMID:27345572

  8. Design and demonstrate the performance of cryogenic components representative of space vehicles: Start basket liquid acquisition device performance analysis

    NASA Technical Reports Server (NTRS)

    1987-01-01

    The objective was to design, fabricate and test an integrated cryogenic test article incorporating both fluid and thermal propellant management subsystems. A 2.2 m (87 in) diameter aluminum test tank was outfitted with multilayer insulation, helium purge system, low-conductive tank supports, thermodynamic vent system, liquid acquisition device and immersed outflow pump. Tests and analysis performed on the start basket liquid acquisition device and studies of the liquid retention characteristics of fine mesh screens are discussed.

  9. Numerical investigation of performance of vane-type propellant management device by VOF methods

    NASA Astrophysics Data System (ADS)

    Liu, J. T.; Zhou, C.; Wu, Y. L.; Zhuang, B. T.; Li, Y.

    2015-01-01

    The orbital propellant management performance of the vane-type tank is so important for the propellant system and it determines the lifetime of the satellite. The propellant in the tank can be extruded by helium gas. To study the two phase distribution in the vane-type surface tension tank and the capability of the vane-type propellant management device (PMD), a large volume vane-type surface tension tank is analysed using 3-D unsteady numerical simulations. VOF methods are used to analyse the location of the interface of the two phase. Performances of the propellant acquisition vanes and propellant refillable reservoir in the tank are investigated. The flow conductivity of the propellant acquisition vanes and the liquid storage capacity of propellant refillable reservoir can be affected by the value of the gravity and the volume of the propellant in the tank. To avoid the large resistance causing by surface tension in an outflow of a small hole, the design of the vanes in a propellant refillable reservoir should have suitable space.

  10. How neighbor canopy architecture affects target plant performance

    SciTech Connect

    Tremmel, D.C.; Bazzaz, F.A. )

    1993-10-01

    Plant competition occurs through the negative effects that individual plants have on resource availability to neighboring individuals. Therefore competition experiments need to examine how different species change resource availability to their neighbors, and how different species respond to these changes-allocationally, architecturally, and physiologically-through time. In a greenhouse study we used a model system of annuals to examine how canopies of species having differing morphologies differed in their architectures and light-interception abilities, and how different species performed when grown in these canopies. Abutilon theophrasti, Datura stramonium, and Polygonum pensylvanicum were grown as [open quotes]targets[close quotes]. Plants were grown in pots, with one target plant and four neighbor plants. Detailed measurements of neighbor canopy structure and target plant canopy architecture were made at five harvests. Species with different morphologies showed large differences in canopy structure, particularly when grass and forb species were compared. Setaria, a grass, had a more open canopy than the other species (all forbs), and was a consistently weak competitor. Overall, however, the relative effects of different neighbors on target biomass varied with target species. Target biomass was poorly correlated with neighbor biomass and leaf area, but was highly correlated with a measure of target light-interception ability that took into account both target leaf deployment and neighbor light interception. Despite clear differences among neighbor species in canopy structure and effect on light penetration, the results suggest no broad generalizations about the effects of different species as neighbors. Knowledge of morphological, physiological, and life history characteristics of both the target and neighbor species may be necessary to explain the results of their competition. 53 refs., 4 figs., 4 tabs.

  11. Reynolds Number Effects on the Performance of Lateral Control Devices

    NASA Technical Reports Server (NTRS)

    Mineck, Raymond E.

    2000-01-01

    The influence of Reynolds number on the performance of outboard spoilers and ailerons was investigated on a generic subsonic transport configuration in the National Transonic Facility over a chord Reynolds number range 41 from 3x10(exp 6) to 30xl0(exp 6) and a Mach number range from 0.50 to 0.94, Spoiler deflection angles of 0, 10, 15, and 20 deg and aileron deflection angles of -10, 0, and 10 deg were tested. Aeroelastic effects were minimized by testing at constant normalized dynamic pressure conditions over intermediate Reynolds number ranges. Results indicated that the increment in rolling moment due to spoiler deflection generally becomes more negative as the Reynolds number increases from 3x10(exp 6) to 22x10(exp 6) with only small changes between Reynolds numbers of 22x10(exp 6) and 30x10(exp 6). The change in the increment in rolling moment coefficient with Reynolds number for the aileron deflected configuration is generally small with a general trend of increasing magnitude with increasing Reynolds number.

  12. A simple device for high-precision head image registration: Preliminary performance and accuracy tests

    SciTech Connect

    Pallotta, Stefania

    2007-05-15

    The purpose of this paper is to present a new device for multimodal head study registration and to examine its performance in preliminary tests. The device consists of a system of eight markers fixed to mobile carbon pipes and bars which can be easily mounted on the patient's head using the ear canals and the nasal bridge. Four graduated scales fixed to the rigid support allow examiners to find the same device position on the patient's head during different acquisitions. The markers can be filled with appropriate substances for visualisation in computed tomography (CT), magnetic resonance, single photon emission computer tomography (SPECT) and positron emission tomography images. The device's rigidity and its position reproducibility were measured in 15 repeated CT acquisitions of the Alderson Rando anthropomorphic phantom and in two SPECT studies of a patient. The proposed system displays good rigidity and reproducibility characteristics. A relocation accuracy of less than 1,5 mm was found in more than 90% of the results. The registration parameters obtained using such a device were compared to those obtained using fiducial markers fixed on phantom and patient heads, resulting in differences of less than 1 deg. and 1 mm for rotation and translation parameters, respectively. Residual differences between fiducial marker coordinates in reference and in registered studies were less than 1 mm in more than 90% of the results, proving that the device performed as accurately as noninvasive stereotactic devices. Finally, an example of multimodal employment of the proposed device is reported.

  13. Power electronics performance in cryogenic environment: evaluation for use in HTS power devices

    NASA Astrophysics Data System (ADS)

    Pereira, P.; Valtchev, S.; Pina, J.; Gonçalves, A.; Ventim Neves, M.; Rodrigues, A. L.

    2008-02-01

    Power electronics (PE) plays a major role in electrical devices and systems, namely in electromechanical drives, in motor and generator controllers, and in power grids, including high-voltage DC (HVDC) power transmission. PE is also used in devices for the protection against grid disturbances, like voltage sags or power breakdowns. To cope with these disturbances, back-up energy storage devices are used, like uninterruptible power supplies (UPS) and flywheels. Some of these devices may use superconductivity. Commercial PE semiconductor devices (power diodes, power MOSFETs, IGBTs, power Darlington transistors and others) are rarely (or never) experimented for cryogenic temperatures, even when designed for military applications. This means that its integration with HTS power devices is usually done in the hot environment, raising several implementation restrictions. These reasons led to the natural desire of characterising PE under extreme conditions, e. g. at liquid nitrogen temperatures, for use in HTS devices. Some researchers expect that cryogenic temperatures may increase power electronics' performance when compared with room-temperature operation, namely reducing conduction losses and switching time. Also the overall system efficiency may increase due to improved properties of semiconductor materials at low temperatures, reduced losses, and removal of dissipation elements. In this work, steady state operation of commercial PE semiconductors and devices were investigated at liquid nitrogen and room temperatures. Performances in cryogenic and room temperatures are compared. Results help to decide which environment is to be used for different power HTS applications.

  14. Affective Responses to an Aerobic Dance Class: The Impact of Perceived Performance.

    ERIC Educational Resources Information Center

    Bartholomew, John B.; Miller, Bridget M.

    2002-01-01

    Tested the mastery hypothesis as an explanation for the affective benefits of acute exercise. Undergraduate women from a self-selected aerobic dance class rated their exercise performance following class. Affect questionnaires were completed before and at 5 and 20 minutes after the class. Results showed an overall improvement in affect following…

  15. Effect of two yellow delta-emitting layers on device performance of phosphorescent white organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Zhao, Juan; Yu, Junsheng; Wang, Xiao; Zhang, Lei

    2013-03-01

    Phosphorescent white organic light-emitting devices (WOLEDs) with a structure of ITO/TAPC/δ-EML1/mCP:FIrpic/δ-EML2/Bphen/Mg:Ag were fabricated, wherein two ultrathin and host-free emitting layers (EMLs) were formed by using yellow bis[2-(4-tertbutylphenyl)benzothiazolato-N,C2'] iridium (acetylacetonate) [(tbt)2Ir(acac)] and referred to as delta-EMLs (δ-EML1 and δ-EML2). By adjusting the thicknesses of δ-EMLs, a maximum current efficiency of 27.6 cd/A, an external quantum efficiency (EQE) of 10%, together with low efficiency roll-off at high luminance were achieved. The results showed that δ-EML1 played a dominant role on charge carrier trapping, while δ-EML2 had major impact on yellow light emission, which were highly sensitive to the location of δ-EMLs. Furthermore, by introducing 5-nm Au as anode modifying layer, high device efficiency was maintained along with excellent color stability of warm white emission, displaying color coordinates of (0.38, 0.42) and color temperature of 4348 K at a luminance of 7000 cd/m2. Importantly, explanation and analysis for the influence of both ultrathin δ-EMLs and anode modifying layer on device performance were proposed.

  16. High performance nonvolatile memory devices based on Cu2-xSe nanowires

    NASA Astrophysics Data System (ADS)

    Wu, Chun-Yan; Wu, Yi-Liang; Wang, Wen-Jian; Mao, Dun; Yu, Yong-Qiang; Wang, Li; Xu, Jun; Hu, Ji-Gang; Luo, Lin-Bao

    2013-11-01

    We report on the rational synthesis of one-dimensional Cu2-xSe nanowires (NWs) via a solution method. Electrical analysis of Cu2-xSe NWs based memory device exhibits a stable and reproducible bipolar resistive switching behavior with a low set voltage (0.3-0.6 V), which can enable the device to write and erase data efficiently. Remarkably, the memory device has a record conductance switching ratio of 108, much higher than other devices ever reported. At last, a conducting filaments model is introduced to account for the resistive switching behavior. The totality of this study suggests that the Cu2-xSe NWs are promising building blocks for fabricating high-performance and low-consumption nonvolatile memory devices.

  17. Charge transfer through amino groups-small molecules interface improving the performance of electroluminescent devices

    NASA Astrophysics Data System (ADS)

    Havare, Ali Kemal; Can, Mustafa; Tozlu, Cem; Kus, Mahmut; Okur, Salih; Demic, Şerafettin; Demirak, Kadir; Kurt, Mustafa; Icli, Sıddık

    2016-05-01

    A carboxylic group functioned charge transporting was synthesized and self-assembled on an indium tin oxide (ITO) anode. A typical electroluminescent device [modified ITO/TPD (50 nm)/Alq3 (60 nm)/LiF (2 nm)/(120 nm)] was fabricated to investigate the effect of the amino groups-small molecules interface on the characteristics of the device. The increase in the surface work function of ITO is expected to facilitate the hole injection from the ITO anode to the Hole Transport Layer (HTL) in electroluminescence. The modified electroluminescent device could endure a higher current and showed a much higher luminance than the nonmodified one. For the produced electroluminescent devices, the I-V characteristics, optical characterization and quantum yields were performed. The external quantum efficiency of the modified electroluminescent device is improved as the result of the presence of the amino groups-small molecules interface.

  18. Electrical performance analysis of IC package for the high-end memory device

    NASA Astrophysics Data System (ADS)

    Lee, Dong H.; Han, Chan M.

    1997-08-01

    The developments of processing technology and design make it possible to increase the clock speed and the number of input outputs (I/Os) in memory devices. The interconnections of IC package are considered as an important factor to decide the performance of the memory devices. In order to overcome the limitations of the conventional package, new types of package such as Ball Grid Array (BGA), chip scale package or flip chip bonding are adopted by many IC manufacturers. The present work has compared the electrical performances of 3 different packages to provide deign guide for IC packages of the high performance memory devices in the future. Those packages are designed for the same memory devices to confront to the diversity of memory market demand. The conventional package using lead frame, wire bonded BGA using printed circuit board substrate and flip chip bonded BGA are analyzed. Their electrical performances are compared in the area of signal delay and coupling effect between signal interconnections. The electrical package modeling is built by extracting parasitic of interconnections in IC package through electro-magnetic simulations. The electrical package modeling is built by extracting parasitic of interconnections in IC package through electro-magnetic simulations. The analysis of electrical behavior is performed using SPICE model which is made to represent the real situation. The methodology presented is also capable of determining the most suitable memory package for a particular device based on the electrical performance.

  19. An Analysis of Factors That Affect the Educational Performance of Agricultural Students

    ERIC Educational Resources Information Center

    Greenway, Gina

    2012-01-01

    Many factors contribute to student achievement. This study focuses on three areas: how students learn, how student personality type affects performance, and how course format affects performance outcomes. The analysis sought to improve understanding of the direction and magnitude with which each of these factors impacts student success. Improved…

  20. Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors

    SciTech Connect

    Ha, Tae-Jun

    2015-03-15

    Metal-oxide based thin-film transistors (oxide-TFTs) are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.

  1. Performance enhancement of organic photovoltaic devices enabled by Au nanoarrows inducing surface plasmonic resonance effect.

    PubMed

    Li, Shujun; Li, Zhiqi; Zhang, Xinyuan; Zhang, Zhihui; Liu, Chunyu; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-09-21

    The surface plasmon resonance (SPR) effect of metal nanoparticles is widely employed in organic solar cells to enhance device performance. However, the light-harvesting improvement is highly dependent on the shape of the metal nanoparticles. In this study, the significantly enhanced performance upon incorporation of Au nanoarrows in solution-processed organic photovoltaic devices is demonstrated. Incorporating Au nanoarrows into the ZnO cathode buffer layer results in superior broadband optical absorption improvement and a power conversion efficiency of 7.82% is realized with a 27.3% enhancement compared with the control device. The experimental and theoretical results indicate that the introduction of Au nanoarrows not only increases optical trapping by the SPR effect but also facilitates exciton generation, dissociation, and charge transport inside the thin film device. PMID:27531663

  2. Restorative effect of oxygen annealing on device performance in HfIZO thin-film transistors

    NASA Astrophysics Data System (ADS)

    Ha, Tae-Jun

    2015-03-01

    Metal-oxide based thin-film transistors (oxide-TFTs) are very promising for use in next generation electronics such as transparent displays requiring high switching and driving performance. In this study, we demonstrate an optimized process to secure excellent device performance with a favorable shift of the threshold voltage toward 0V in amorphous hafnium-indium-zinc-oxide (a-HfIZO) TFTs by using post-treatment with oxygen annealing. This enhancement results from the improved interfacial characteristics between gate dielectric and semiconductor layers due to the reduction in the density of interfacial states related to oxygen vacancies afforded by oxygen annealing. The device statistics confirm the improvement in the device-to-device and run-to-run uniformity. We also report on the photo-induced stability in such oxide-TFTs against long-term UV irradiation, which is significant for transparent displays.

  3. 78 FR 18988 - Establishing the Performance Characteristics of In Vitro Diagnostic Devices for the Detection of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-28

    ...The Food and Drug Administration (FDA) is announcing the availability of the guidance entitled ``Establishing the Performance Characteristics of In Vitro Diagnostic Devices for the Detection of Antibodies to Borrelia burgdorferi.'' FDA is issuing this guidance to provide industry and Agency staff with recommendations for studies to establish the analytical and clinical performance of in vitro......

  4. Enhancement of X-ray performance with new GEC charged coupled devices (CCD)

    NASA Technical Reports Server (NTRS)

    Schwartz, D. A.; Knight, F. K.; Lumb, D.; Chowanietz, E.; Wells, A.

    1985-01-01

    Samples of two GEC charge coupled devices with enhanced X-ray performance have been tested. The P8607, fabricated with reduced linear dimensions, gives the lowest detector noise reported for Fe-55 with a CCD. The deep depletion device P8600-HR gives the best combination of energy resolution and quantum efficiency at 6 keV. The energy resolution vs quantum efficiency trade-off curve are discussed.

  5. Ion implantation in compound semiconductors for high-performance electronic devices

    SciTech Connect

    Zolper, J.C.; Baca, A.G.; Sherwin, M.E.; Klem, J.F.

    1996-05-01

    Advanced electronic devices based on compound semiconductors often make use of selective area ion implantation doping or isolation. The implantation processing becomes more complex as the device dimensions are reduced and more complex material systems are employed. The authors review several applications of ion implantation to high performance junction field effect transistors (JFETs) and heterostructure field effect transistors (HFETs) that are based on compound semiconductors, including: GaAs, AlGaAs, InGaP, and AlGaSb.

  6. Effect of desiccant on the performance of green organic light-emitting device

    NASA Astrophysics Data System (ADS)

    Zhong, Jian; Gao, Zhuo; Yu, Junsheng; Jiang, Yadong

    2011-01-01

    A green organic light-emitting diodes (OLED) with a multilayer structure of indium-tin oxide (ITO)/copper-phthalocyanine (CuPc) (200Å)/ N,N'-bis(1-naphthyl)- N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) (600Å)/ N'- diphenyl- N,N'-tris(8-hydroxyquinoline) aluminium (Alq3) (400Å):10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7- tetrahydro-1 H,5 H,11 H-( l)benzopyropyrano(6,7,8-i, j)quinolizin-11-one (C545T) (2%)/Alq3 (200Å)/LiF (10Å)/Al (1000Å) was prepared via vacuum thermal evaporation. To reduce the impact of water vapor and oxygen on the device, we encapsulated it with a kind of specific and efficient desiccant, called DESIPASTE, under the protection of high-purity nitrogen. By analyzing a series of optical characteristics of OLEDs, the results showed that this desiccant can improve the brightness about 500 and 250 cd/m2 at same driving voltage and current density, respectively. The electroluminescent (EL) spectra were hardly affected except a very weak blue shift of broadband emission peak. It turns out that encapsulation with DESIPASTE is a simple and efficient way to improve the performance of OLED.

  7. Responses to formal performance appraisal feedback: the role of negative affectivity.

    PubMed

    Lam, Simon S K; Yik, Michelle S M; Schaubroeck, John

    2002-02-01

    This study examined the effects of performance appraisal feedback on job and organizational attitudes of tellers (N = 329) in a large international bank. Negative affectivity moderated the link between favorable appraisal feedback and job attitudes. Among the higher rated performers, attitudes were improved 1 month after being notified of favorable appraisal results (Time 2). Improved attitudes persisted 6 months after the performance appraisal (Time 3) among tellers with low negative affectivity but not among those with high negative affectivity. Among the lower rated performers, mean levels of attitudes did not change significantly during the study. PMID:11924542

  8. Factors Affecting Time to Bony Union of Femoral Subtrochanteric Fractures Treated with Intramedullary Devices

    PubMed Central

    Choi, Jung-Yoon; Yoo, Jin-Hee; Chung, Sung-Jae

    2014-01-01

    Purpose To evaluate the factors affecting the bone union time and the occurrence of nonunion after intramedullary nailing of subtrochanteric femoral fractures in adults. Materials and Methods We retrospectively reviewed data from 31 patients (22 men and 9 women) who had undergone femoral intramedullary nailing at least 1 year post-operatively and analyzed the bone union time, nonunion rates, and factors that affected the bone union time according to the fracture classification (AO and Fielding classifications), comminution of the medial cortex, reduction method, and additional cerclage wiring. Results The average union time was 26.4 weeks. There were no differences in the bone union time according to the fracture classification, reduction method, or additional cerclage wiring. Significant differences were found in the bone union time between the medial cortex comminution and non-comminution groups. A relatively strong positive correlation was detected between the degree of post-operative displacement and the bone union time. Nonunion occurred in three cases and there was no failure of implants. Conclusion The bone union time was not affected by the reduction method nor additional cerclage wiring in intramedullary nailing of subtrochanteric femur fractures. Comminution of the medial cortex and the degree of the postoperative displacement of fractures contributed to the delayed time of union.

  9. The differential influences of positive affect, random reward, and performance-contingent reward on cognitive control.

    PubMed

    Fröber, Kerstin; Dreisbach, Gesine

    2014-06-01

    Growing evidence suggests that positive affect and reward have differential effects on cognitive control. So far, however, these effects have never been studied together. Here, the authors present one behavioral study investigating the influences of positive affect and reward (contingent and noncontingent) on proactive control. A modified version of the AX-continuous performance task, which has repeatedly been shown to be sensitive to reward and affect manipulations, was used. In a first phase, two experimental groups received either neutral or positive affective pictures before every trial. In a second phase, the two halves of a given affect group additionally received, respectively, performance-contingent or random rewards. The results replicated the typical affect effect, in terms of reduced proactive control under positive as compared to neutral affect. Also, the typical reward effects associated with increased proactive control were replicated. Most interestingly, performance-contingent reward counteracted the positive affect effect, whereas random reward mirrored that effect. In sum, this study provides first evidence that performance-contingent reward, on the one hand, and positive affect and performance-noncontingent reward, on the other hand, have oppositional effects on cognitive control: Only performance-contingent reward showed a motivational effect in terms of a strategy shift toward increased proactive control, whereas positive affect alone and performance-noncontingent reward reduced proactive control. Moreover, the integrative design of this study revealed the vulnerability of positive affect effects to motivational manipulations. The results are discussed with respect to current neuroscientific theories of the effects of dopamine on affect, reward, and cognitive control. PMID:24659000

  10. Identifying Affective Domains That Correlate and Predict Mathematics Performance in High-Performing Students in Singapore

    ERIC Educational Resources Information Center

    Lim, Siew Yee; Chapman, Elaine

    2015-01-01

    Past studies have shown that distinct yet highly correlated sub-constructs of three broad mathematics affective variables: (a) motivation, (b) attitudes and (c) anxiety, have varying degree of correlation with mathematics achievement. The sub-constructs of these three affective constructs are as follows: (a) (i) amotivation, (ii) external…

  11. Combined effects of positive and negative affectivity and job satisfaction on job performance and turnover intentions.

    PubMed

    Bouckenooghe, Dave; Raja, Usman; Butt, Arif Nazir

    2013-01-01

    Capturing data from employee-supervisor dyads (N = 321) from eight organizations in Pakistan, including human service organizations, an electronics assembly plant, a packaging material manufacturing company, and a small food processing plant, we used moderated regression analysis to examine whether the relationships between trait affect (positive affectivity [PA] and negative affectivity [NA]) and two key work outcome variables (job performance and turnover) are contingent upon the level of job satisfaction. We applied the Trait Activation Theory to explain the moderating effect of job satisfaction on the relationship between affect and performance and between affect and turnover. Overall, the data supported our hypotheses. Positive and negative affectivity influenced performance and the intention to quit, and job satisfaction moderated these relationships. We discuss in detail the results of these findings and their implications for research and practice. PMID:23469474

  12. Aerodynamic Design Criteria for Class 8 Heavy Vehicles Trailer Base Devices to Attain Optimum Performance

    SciTech Connect

    Salari, K; Ortega, J

    2010-12-13

    Lawrence Livermore National Laboratory (LLNL) as part of its Department of Energy (DOE), Energy Efficiency and Renewable Energy (EERE), and Vehicle Technologies Program (VTP) effort has investigated class 8 tractor-trailer aerodynamics for many years. This effort has identified many drag producing flow structures around the heavy vehicles and also has designed and tested many new active and passive drag reduction techniques and concepts for significant on the road fuel economy improvements. As part of this effort a database of experimental, computational, and conceptual design for aerodynamic drag reduction devices has been established. The objective of this report is to provide design guidance for trailer base devices to improve their aerodynamic performance. These devices are commonly referred to as boattails, base flaps, tail devices, and etc. The information provided here is based on past research and our most recent full-scale experimental investigations in collaboration with Navistar Inc. Additional supporting data from LLNL/Navistar wind tunnel, track test, and on the road test will be published soon. The trailer base devices can be identified by 4 flat panels that are attached to the rear edges of the trailer base to form a closed cavity. These devices have been engineered in many different forms such as, inflatable and non-inflatable, 3 and 4-sided, closed and open cavity, and etc. The following is an in-depth discussion with some recommendations, based on existing data and current research activities, of changes that could be made to these devices to improve their aerodynamic performance. There are 6 primary factors that could influence the aerodynamic performance of trailer base devices: (1) Deflection angle; (2) Boattail length; (3) Sealing of edges and corners; (4) 3 versus 4-sided, Position of the 4th plate; (5) Boattail vertical extension, Skirt - boattail transition; and (6) Closed versus open cavity.

  13. Achieving high performance polymer optoelectronic devices for high efficiency, long lifetime and low fabrication cost

    NASA Astrophysics Data System (ADS)

    Huang, Jinsong

    This thesis described three types of organic optoelectronic devices: polymer light emitting diodes (PLED), polymer photovoltaic solar cell, and organic photo detector. The research in this work focuses improving their performance including device efficiency, operation lifetime simplifying fabrication process. With further understanding in PLED device physics, we come up new device operation model and improved device architecture design. This new method is closely related to understanding of the science and physics at organic/metal oxide and metal oxide/metal interface. In our new device design, both material and interface are considered in order to confine and balance all injected carriers, which has been demonstrated very be successful in increasing device efficiency. We created two world records in device efficiency: 18 lm/W for white emission fluorescence PLED, 22 lm/W for red emission phosphorescence PLED. Slow solvent drying process has been demonstrated to significantly increase device efficiency in poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61-butyric acid methyl ester (PCBM) mixture polymer solar cell. From the mobility study by time of flight, the increase of efficiency can be well correlated to the improved carrier transport property due to P3HT crystallization during slow solvent drying. And it is found that, similar to PLED, balanced carrier mobility is essential in high efficient polymer solar cell. There is also a revolution in our device fabrication method. A unique device fabrication method is presented by an electronic glue based lamination process combined with interface modification as a one-step polymer solar cell fabrication process. It can completely skip the thermal evaporation process, and benefit device lifetime by several merits: no air reactive. The device obtained is metal free, semi-transparent, flexible, self-encapsulated, and comparable efficiency with that by regular method. We found the photomultiplication (PM) phenomenon in C

  14. 49 CFR 232.405 - Design and performance standards for two-way end-of-train devices.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Design and performance standards for two-way end-of-train devices. 232.405 Section 232.405 Transportation Other Regulations Relating to Transportation... Design and performance standards for two-way end-of-train devices. Two-way end-of-train devices shall...

  15. A performance comparison of the paediatric i-gel with other supraglottic airway devices.

    PubMed

    Smith, P; Bailey, C R

    2015-01-01

    We performed a review of published literature comparing the i-gel with other supraglottic airway devices in children. Sixty-two articles were identified following a literature search; we included data from 14 randomised controlled trials and eight observational studies that compared i-gel sizes 1-2.5 with other commonly used, equivalently-sized, devices. The primary outcome in most studies was oropharyngeal leak pressure. In the 14 randomised trials the i-gel performed the same as the comparator device in five trials, significantly better in eight studies (p < 0.05) and significantly worse in one (p < 0.01). Seven studies assessed fibreoptic views of the larynx through the device; two found significantly better views through the i-gel. Three studies reported a shorter insertion time for the i-gel, whereas two reported a longer time. Insertion success rate, gastric tube placement and complications were similar for all the devices. Seven of the eight observational studies measured average oropharyngeal leak pressures of 20-27 cmH2O and all had first-time insertion success rates exceeding 90%. We conclude that the i-gel is at least equivalent to other supraglottic airway devices currently available for use in children, and may enable a higher oropharyngeal leak pressure and an improved fibreoptic view of the glottis. PMID:25187212

  16. Performance of micro two-level heat devices with prior information

    NASA Astrophysics Data System (ADS)

    Long, Rui; Liu, Wei

    2015-09-01

    The performance of micro two-level heat engines and refrigerators with prior information has been analyzed under the maximum power output and maximum χ figure of merit, respectively. Under the asymmetric limits, the Curzon-Ahlborn efficiency and Curzon-Ahlborn coefficient of performance are retrieved. However, they are independent of the probability distribution function of particle numbers. Furthermore, the results are in accord with previous literatures. They shed light on that the model proposed in this paper can describe any specified models with concrete prior probability distribution such as two-level quantum heat devices and Brownian heat devices with prior information.

  17. Daily fluctuations in positive affect positively co-vary with working memory performance.

    PubMed

    Brose, Annette; Lövdén, Martin; Schmiedek, Florian

    2014-02-01

    Positive affect is related to cognitive performance in multiple ways. It is associated with motivational aspects of performance, affective states capture attention, and information processing modes are a function of affect. In this study, we examined whether these links are relevant within individuals across time when they experience minor ups and downs of positive affect and work on cognitive tasks in the laboratory on a day-to-day basis. Using a microlongitudinal design, 101 younger adults (20-31 years of age) worked on 3 working memory tasks on about 100 occasions. Every day, they also reported on their momentary affect and their motivation to work on the tasks. In 2 of the 3 tasks, performance was enhanced on days when positive affect was above average. This performance enhancement was also associated with more motivation. Importantly, increases in task performance on days with above-average positive affect were mainly unrelated to variations in negative affect. This study's results are in line with between-person findings suggesting that high levels of well-being are associated with successful outcomes. They imply that success on cognitively demanding tasks is more likely on days when feeling happier. PMID:24364855

  18. Development of Substrate Structure CdTe Photovoltaic Devices with Performance Exceeding 10%: Preprint

    SciTech Connect

    Dhere, R. G.; Duenow, J. N.; DeHart, C. M.; Li, J. V.; Kuciauskas, D.; Gessert, T. A.

    2012-08-01

    Most work on CdTe-based solar cells has focused on devices with a superstrate structure. This focus is due to the early success of the superstrate structure in producing high-efficiency cells, problems of suitable ohmic contacts for lightly doped CdTe, and the simplicity of the structure for manufacturing. The development of the CdCl2 heat treatment boosted CdTe technology and perpetuated the use of the superstrate structure. However, despite the beneficial attributes of the superstrate structure, devices with a substrate structure are attractive both commercially and scientifically. The substrate structure eliminates the need for transparent superstrates and thus allows the use of flexible metal and possibly plastic substrates. From a scientific perspective, it allows better control in forming the junction and direct access to the junction for detailed analysis. Research on such devices has been limited. The efficiency of these devices has been limited to around 8% due to low open-circuit voltage (Voc) and fill factor. In this paper, we present our recent device development efforts at NREL on substrate-structure CdTe devices. We have found that processing parameters required to fabricate high-efficiency substrate CdTe PV devices differ from those necessary for traditional superstrate CdTe devices. We have worked on a variety of contact materials including Cu-doped ZnTe and CuxTe. We will present a comparative analysis of the performance of these contacts. In addition, we have studied the influence of fabrication parameters on junction properties. We will present an overview of our development work, which has led to CdTe devices with Voc values of more than 860 mV and NREL-confirmed efficiencies approaching 11%.

  19. Does medical students’ clinical performance affect their actual performance during medical internship?

    PubMed Central

    Han, Eui-Ryoung; Chung, Eun-Kyung

    2016-01-01

    INTRODUCTION This study examines the relationship between the clinical performance of medical students and their performance as doctors during their internships. METHODS This retrospective study involved 63 applicants of a residency programme conducted at Chonnam National University Hospital, South Korea, in November 2012. We compared the performance of the applicants during their internship with their clinical performance during their fourth year of medical school. The performance of the applicants as interns was periodically evaluated by the faculty of each department, while their clinical performance as fourth-year medical students was assessed using the Clinical Performance Examination (CPX) and the Objective Structured Clinical Examination (OSCE). RESULTS The performance of the applicants as interns was positively correlated with their clinical performance as fourth-year medical students, as measured by the CPX and OSCE. The performance of the applicants as interns was moderately correlated with the patient-physician interaction items addressing communication and interpersonal skills in the CPX. CONCLUSION The clinical performance of medical students during their fourth year in medical school was related to their performance as medical interns. Medical students should be trained to develop good clinical skills through actual encounters with patients or simulated encounters using manikins, to enable them to become more competent doctors. PMID:26768172

  20. Altering the interfacial morphology of polymer light-emitting diodes using polymer interlayers: effect on hole injection and device performance

    NASA Astrophysics Data System (ADS)

    Harding, M. James; Poplavskyy, Dmitry; Choong-En, Vi; So, Franky; Campbell, Alasdair J.

    2006-08-01

    We report preliminary studies of the nature of hole injection from poly(3,4-ethylenedioxythiophene)/polystyrenesulphonic acid (PEDOT:PSS) into three commercial conjugated light emitting polymers (LEPs). Sumation's LUMATION Green 1300, LUMATION Blue, and Merck's SuperYellow LEPs are studied in combination with interlayers of poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), and poly[9,9-dioctylfluorene-co-(bis-N,N'-(3-carboxyphenyl)-bis-N,N'-phenylbenzidine)] (BFA). Despite the highest occupied molecular orbitals (HOMOs) of the interlayers being close to that of PEDOT:PSS and the LEP, different interlayers have different effects on hole injection and OLED device performance. We use dark injection transient current method to show that interfacial morphology changes results in modulation of hole trap densities that in turn affect hole injection. Depending on the interlayer/LEP combination partial penetration of interlayer into the LEP layer may also occur resulting in additional changes in the bulk transport properties of the LEP. Our results show that it is not the interfacial energy level alignment but the physical morphology changes at the interface which are important for varying hole injection into the device. A combination of either improved or reduced hole injection due to variations in physical contact, intermixing and trapping at the interlayer/LEP boundary dominate device performance.

  1. Impact of continuing scaling on the device performance of 3D cylindrical junction-less charge trapping memory

    NASA Astrophysics Data System (ADS)

    Xinkai, Li; Zongliang, Huo; Lei, Jin; Dandan, Jiang; Peizhen, Hong; Qiang, Xu; Zhaoyun, Tang; Chunlong, Li; Tianchun, Ye

    2015-09-01

    This work presents a comprehensive analysis of 3D cylindrical junction-less charge trapping memory device performance regarding continuous scaling of the structure dimensions. The key device performance, such as program/erase speed, vertical charge loss, and lateral charge migration under high temperature are intensively studied using the Sentaurus 3D device simulator. Although scaling of channel radius is beneficial for operation speed improvement, it leads to a retention challenge due to vertical leakage, especially enhanced charge loss through TPO. Scaling of gate length not only decreases the program/erase speed but also leads to worse lateral charge migration. Scaling of spacer length is critical for the interference of adjacent cells and should be carefully optimized according to specific cell operation conditions. The gate stack shape is also found to be an important factor affecting the lateral charge migration. Our results provide guidance for high density and high reliability 3D CTM integration. Project supported by the National Natural Science Foundation of China (Nos. 61474137, 61176073, 61306107).

  2. Experimental Research on the Performance of Exhaust Steam Reclaim Device With a Swirling Flow Vane

    NASA Astrophysics Data System (ADS)

    Li, X. L.; Yan, J. J.; Zhang, P. F.; Yang, J. J.; Liu, J. P.

    2010-03-01

    This paper experimentally studied the performance of exhaust steam reclaim device with a swirling flow vane at different inlet water pressures, temperatures, different inlet steam pressures and different distances between the throat and spout. The results indicated that the injection coefficient decreased as the inlet water pressure and temperature increased, respectively. There is a best distance between the throat and spout which makes the injection coefficient reached to its maximal value at the same experimental pressure and temperature, and the value equals to 130 mm in our experimental system. The resistance coefficient has a minimum value which makes the device have the highest outlet water pressure. Compared with the device without a swirling flow vane, it improves the heating performance for higher injection coefficient and exergy efficiency.

  3. Analytical performance of polymer-based microfluidic devices fabricated by computer numerical controlled machining.

    PubMed

    Mecomber, Justin S; Stalcup, Apryll M; Hurd, Doug; Halsall, H Brian; Heineman, William R; Seliskar, Carl J; Wehmeyer, Kenneth R; Limbach, Patrick A

    2006-02-01

    A study comparing the electrophoretic separation performance attainable from microchips molded by masters fabricated using conventional CNC machining techniques with commercial microchips, wire imprinted microchips, and microchips from LIGA molding devices is presented. An electrophoresis-based detection system using fluorescence microscopy was used to determine the analytical utility of these microchips. The separation performance of CNC microchips was comparable to commercially available microchips as well as those fabricated from LIGA masters. The important feature of the CNC machined masters is that they have rapid design-to-device times using routinely available machining tools. This low-cost prototyping approach provides a new entry point for researchers interested in thermoplastic microchips and can accelerate the development of polymer-based lab-on-a-chip devices. PMID:16448071

  4. Effect of Back Contact and Rapid Thermal Processing Conditions on Flexible CdTe Device Performance

    SciTech Connect

    Mahabaduge, Hasitha; Meysing, D. M.; Rance, Will L.; Burst, James M.; Reese, Matthew O.; Wolden, C. A.; Gessert, Timothy A.; Metzger, Wyatt K.; Garner, S.; Barnes, Teresa M.

    2015-06-14

    Flexible CdTe solar cells on ultra-thin glass substrates can enable new applications that require high specific power, unique form-factors, and low manufacturing costs. To be successful, these cells must be cost competitive, have high efficiency, and have high reliability. Here we present back contact processing conditions that enabled us to achieve over 16% efficiency on flexible Corning (R) Willow (R) Glass substrates. We used co-evaporated ZnTe:Cu and Au as our back contact and used rapid thermal processing (RTP) to activate the back contact. Both the ZnTe to Cu ratio and the RTP activation temperature provide independent control over the device performance. We have investigated the influence of various RTP conditions to Cu activation and distribution. Current density-voltage, capacitance-voltage measurements along with device simulations were used to examine the device performance in terms of ZnTe to Cu ratio and rapid thermal activation temperature.

  5. Using a False Biofeedback Methodology to Explore Relationships between Learners' Affect, Metacognition, and Performance

    ERIC Educational Resources Information Center

    Strain, Amber Chauncey; Azevedo, Roger; D'Mello, Sidney K.

    2013-01-01

    We used a false-biofeedback methodology to manipulate physiological arousal in order to induce affective states that would influence learners' metacognitive judgments and learning performance. False-biofeedback is a method used to induce physiological arousal (and resultant affective states) by presenting learners with audio stimuli of false heart…

  6. Performance-Based Occupational Affective Behavior Analysis (OABA). Implementation and Supporting Research.

    ERIC Educational Resources Information Center

    Pucel, David J.; And Others

    This document contains two sections: implementation of the performance-based Occupational Affective Behavior Analysis (OABA), and supporting research. Section 1 presents OABA, an analytic procedure designed to identify those affective behaviors important to success in an occupation, and gives directions on how to implement the procedure. The…

  7. Investigating Learner Affective Performance in Web-Based Learning by Using Entrepreneurship as a Metaphor

    ERIC Educational Resources Information Center

    Liu, Ming-Chou; Chi, Ming-Hsiao

    2012-01-01

    In the era of the Internet, factors which influence effective learning in a Web-based learning environment are well worth exploring. In addition to knowledge acquisition and skills training, affect is also an important factor, since successful learning requires excellent affective performance. Thus this study focuses on learners' affective…

  8. To branch out or stay focused? Affective shifts differentially predict organizational citizenship behavior and task performance.

    PubMed

    Yang, Liu-Qin; Simon, Lauren S; Wang, Lei; Zheng, Xiaoming

    2016-06-01

    We draw from personality systems interaction (PSI) theory (Kuhl, 2000) and regulatory focus theory (Higgins, 1997) to examine how dynamic positive and negative affective processes interact to predict both task and contextual performance. Using a twice-daily diary design over the course of a 3-week period, results from multilevel regression analysis revealed that distinct patterns of change in positive and negative affect optimally predicted contextual and task performance among a sample of 71 employees at a medium-sized technology company. Specifically, within persons, increases (upshifts) in positive affect over the course of a workday better predicted the subsequent day's organizational citizenship behavior (OCB) when such increases were coupled with decreases (downshifts) in negative affect. The optimal pattern of change in positive and negative affect differed, however, in predicting task performance. That is, upshifts in positive affect over the course of the workday better predicted the subsequent day's task performance when such upshifts were accompanied by upshifts in negative affect. The contribution of our findings to PSI theory and the broader affective and motivation regulation literatures, along with practical implications, are discussed. (PsycINFO Database Record PMID:26882443

  9. Psychological Factor Affecting English Speaking Performance for the English Learners in Indonesia

    ERIC Educational Resources Information Center

    Haidara, Youssouf

    2016-01-01

    In every learning situation or environment, human psychology plays a significant role. English speaking is a language skill that is highly affected by human psychology. This research aimed at describing the psychological factor that affects negatively the English speaking performance for the English learners in Indonesia. A descriptive qualitative…

  10. Affect, Curiosity, and Socialization-Related Learning: A Path Analysis of Antecedents to Job Performance.

    ERIC Educational Resources Information Center

    Reio, Thomas G.; Callahan, Jamie L.

    Affect, curiosity, and socialization-relation were explored as potential mediators of the relationship between both state and trait affect and job performance. The cross-sectional sample consisted of 81 women and 152 men between the ages of 17 and 50 or older. The typical participant was a male Caucasian under the age of 40 with some college…

  11. Job Satisfaction and Performance: The Moderating Effects of Value Attainment and Affective Disposition.

    ERIC Educational Resources Information Center

    Hochwarter, Wayne A.; Perrewe, Pamela L.; Ferris, Gerald R.; Brymer, Robert A.

    1999-01-01

    A study of 270 hotel managers found that the strongest positive relationship between job satisfaction and performance occurred when high attainment of values associated with work was coupled with high-positive or low-negative affective disposition. (SK)

  12. Subjective cognitive complaints, affective distress, and objective cognitive performance in Persian Gulf War veterans.

    PubMed

    Binder, L M; Storzbach, D; Anger, W K; Campbell, K A; Rohlman, D S; of the Portland Environmental, O M; Center, H R

    1999-08-01

    We examined subjective cognitive complaints, affective distress, and cognitive performance in Persian Gulf veterans who reported illness and cognitive complaints. We predicted a stronger relationship between subjective cognitive complaints and affective distress than between subjective cognitive complaints and objective cognitive performance. This prediction was confirmed in a sample of 100 veterans. The results suggest that cognitive impairment should not be diagnosed in this population without objective confirmation with cognitive testing. PMID:14590580

  13. High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores.

    PubMed

    Hossain, Md Sharafat; Al-Dirini, Feras; Hossain, Faruque M; Skafidas, Efstratios

    2015-01-01

    Thermoelectric properties of Graphene nano-ribbons (GNRs) with nanopores (NPs) are explored for a range of pore dimensions in order to achieve a high performance two-dimensional nano-scale thermoelectric device. We reduce thermal conductivity of GNRs by introducing pores in them in order to enhance their thermoelectric performance. The electrical properties (Seebeck coefficient and conductivity) of the device usually degrade with pore inclusion; however, we tune the pore to its optimal dimension in order to minimize this degradation, enhancing the overall thermoelectric performance (high ZT value) of our device. We observe that the side channel width plays an important role to achieve optimal performance while the effect of pore length is less pronounced. This result is consistent with the fact that electronic conduction in GNRs is dominated along its edges. Ballistic transport regime is assumed and a semi-empirical method using Huckel basis set is used to obtain the electrical properties, while the phononic system is characterized by Tersoff empirical potential model. The proposed device structure has potential applications as a nanoscale local cooler and as a thermoelectric power generator. PMID:26083450

  14. Introduction: feature issue on phantoms for the performance evaluation and validation of optical medical imaging devices.

    PubMed

    Hwang, Jeeseong; Ramella-Roman, Jessica C; Nordstrom, Robert

    2012-06-01

    The editors introduce the Biomedical Optics Express feature issue on "Phantoms for the Performance Evaluation and Validation of Optical Medical Imaging Devices." This topic was the focus of a technical workshop that was held on November 7-8, 2011, in Washington, D.C. The feature issue includes 13 contributions from workshop attendees. PMID:22741084

  15. Identification of tasks performed by stroke patients using a mobility assistive device.

    PubMed

    Hester, Todd; Sherrill, Delsey M; Hamel, Mathieu; Perreault, Karine; Boissy, Patrick; Bonato, Paolo

    2006-01-01

    Many stroke patients are prescribed canes or other mobility assistive devices. Once taken home, these mobility assistive devices are often abandoned or misused. A means for assessing the use of the cane in the home and community settings is required to assist clinicians in the prescription of these devices. In this study, we propose the use of wearable sensors to identify tasks performed by stroke patients with a mobility assistive device. Subjects performed ten tasks with a three-axis accelerometer attached to their ankle and a neural network was trained to identify the task being performed. Results from 15 stroke patients indicated that these motor tasks can be reliably identified with a median sensitivity of 90 % at a median specificity of 95%. These results indicate that it is possible to use a single module with a three-axis accelerometer attached to the ankle to reliably identify motor tasks associated with the use of a cane. Therefore, we envision that the methodology presented in this paper could be used to evaluate the use of a cane in the context of the task being performed. PMID:17946896

  16. High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores

    PubMed Central

    Sharafat Hossain, Md; Al-Dirini, Feras; Hossain, Faruque M.; Skafidas, Efstratios

    2015-01-01

    Thermoelectric properties of Graphene nano-ribbons (GNRs) with nanopores (NPs) are explored for a range of pore dimensions in order to achieve a high performance two-dimensional nano-scale thermoelectric device. We reduce thermal conductivity of GNRs by introducing pores in them in order to enhance their thermoelectric performance. The electrical properties (Seebeck coefficient and conductivity) of the device usually degrade with pore inclusion; however, we tune the pore to its optimal dimension in order to minimize this degradation, enhancing the overall thermoelectric performance (high ZT value) of our device. We observe that the side channel width plays an important role to achieve optimal performance while the effect of pore length is less pronounced. This result is consistent with the fact that electronic conduction in GNRs is dominated along its edges. Ballistic transport regime is assumed and a semi-empirical method using Huckel basis set is used to obtain the electrical properties, while the phononic system is characterized by Tersoff empirical potential model. The proposed device structure has potential applications as a nanoscale local cooler and as a thermoelectric power generator. PMID:26083450

  17. High Performance Graphene Nano-ribbon Thermoelectric Devices by Incorporation and Dimensional Tuning of Nanopores

    NASA Astrophysics Data System (ADS)

    Sharafat Hossain, Md; Al-Dirini, Feras; Hossain, Faruque M.; Skafidas, Efstratios

    2015-06-01

    Thermoelectric properties of Graphene nano-ribbons (GNRs) with nanopores (NPs) are explored for a range of pore dimensions in order to achieve a high performance two-dimensional nano-scale thermoelectric device. We reduce thermal conductivity of GNRs by introducing pores in them in order to enhance their thermoelectric performance. The electrical properties (Seebeck coefficient and conductivity) of the device usually degrade with pore inclusion; however, we tune the pore to its optimal dimension in order to minimize this degradation, enhancing the overall thermoelectric performance (high ZT value) of our device. We observe that the side channel width plays an important role to achieve optimal performance while the effect of pore length is less pronounced. This result is consistent with the fact that electronic conduction in GNRs is dominated along its edges. Ballistic transport regime is assumed and a semi-empirical method using Huckel basis set is used to obtain the electrical properties, while the phononic system is characterized by Tersoff empirical potential model. The proposed device structure has potential applications as a nanoscale local cooler and as a thermoelectric power generator.

  18. Performance Improvement of Total Ionization Dose Radiation Sensor Devices Using Fluorine-Treated MOHOS.

    PubMed

    Hsieh, Wen-Ching; Lee, Hao-Tien Daniel; Jong, Fuh-Cheng; Wu, Shich-Chuan

    2016-01-01

    Fluorine-treated titanium nitride-silicon oxide-hafnium oxide-silicon oxide-silicon devices (hereafter F-MOHOS) are candidates for total ionization dose (TID) radiation sensor applications. The main subject of the study reportedherein is the performance improvement in terms of TID radiation-induced charge generation effect and charge-retention reliability characterization for F-MOHOS devices. In the case of F-MOHOS TID radiation sensors, the gamma radiation induces a significant decrease of threshold voltage VT and the radiation-induced charge density is nearly six times larger than that of standard metal-oxide-nitride-oxide-silicon MONOS devices. The decrease of VT for F-MOHOS after gamma irradiation has a strong correlation to the TID up to 5 Mrad gamma irradiation as well. The improvement of charge retention loss for F-MOHOS devices is nearly 15% better than that of metal-oxide-hafnium oxide-oxide-silicon MOHOS devices. The F-MOHOS device described in this study demonstrates better feasibility for non-volatile TID radiation sensing in the future. PMID:27043560

  19. Characterization and performance of WO{sub 3}:Mo/Nafion-H{trademark} electrochromic device

    SciTech Connect

    Pennisi, A.; Simone, F.

    1994-12-31

    Here are presented the results of electrochemical and optical measurements on tungsten trioxide, molybdenum doped (WO{sub 3}:Mo) thin films, electrochemically deposited, assembled with Nafion-H in order to realize an electrochromic (EC) device. The polymer that permits the ionic exchange has a residual viscosity, so that the authors` device cannot be defined as a really solid state device. A good reason for the use of this polymer is its very high proton storage capability, so that, in their devices, it is possible to avoid the presence of a specific ion storage counterelectrode. In this work the authors compare also the electrochromic behavior of devices in dependence on the thermal treatment operated on the electrochemical films after deposition. Analysis has been carried on to reveal morphological characteristics of surface, thickness and stoichiometry of EC compound. Particular attention is paid to the potential waveform used to bias the devices, in order to optimize their performance and to avoid problems of stability and degradation.

  20. AlScN thin film based surface acoustic wave devices with enhanced microfluidic performance

    NASA Astrophysics Data System (ADS)

    Wang, W. B.; Fu, Y. Q.; Chen, J. J.; Xuan, W. P.; Chen, J. K.; Wang, X. Z.; Mayrhofer, P.; Duan, P. F.; Bittner, A.; Schmid, U.; Luo, J. K.

    2016-07-01

    This paper reports the characterization of scandium aluminum nitride (Al1‑x Sc x N, x  =  27%) films and discusses surface acoustic wave (SAW) devices based on them. Both AlScN and AlN films were deposited on silicon by sputtering and possessed columnar microstructures with (0 0 0 2) crystal orientation. The AlScN/Si SAW devices showed improved electromechanical coupling coefficients (K 2, ~2%) compared with pure AlN films (<0.5%). The performance of the two types of devices was also investigated and compared, using acoustofluidics as an example. The AlScN/Si SAW devices achieved much lower threshold powers for the acoustic streaming and pumping of liquid droplets, and the acoustic streaming and pumping velocities were 2  ×  and 3  ×  those of the AlN/Si SAW devices, respectively. Mechanical characterization showed that the Young’s modulus and hardness of the AlN film decreased significantly when Sc was doped, and this was responsible for the decreased acoustic velocity and resonant frequency, and the increased temperature coefficient of frequency, of the AlScN SAW devices.

  1. Performance Improvement of Total Ionization Dose Radiation Sensor Devices Using Fluorine-Treated MOHOS

    PubMed Central

    Hsieh, Wen-Ching; Lee, Hao-Tien Daniel; Jong, Fuh-Cheng; Wu, Shich-Chuan

    2016-01-01

    Fluorine-treated titanium nitride–silicon oxide–hafnium oxide–silicon oxide–silicon devices (hereafter F-MOHOS) are candidates for total ionization dose (TID) radiation sensor applications. The main subject of the study reportedherein is the performance improvement in terms of TID radiation-induced charge generation effect and charge-retention reliability characterization for F-MOHOS devices. In the case of F-MOHOS TID radiation sensors, the gamma radiation induces a significant decrease of threshold voltage VT and the radiation-induced charge density is nearly six times larger than that of standard metal–oxide–nitride–oxide–silicon MONOS devices. The decrease of VT for F-MOHOS after gamma irradiation has a strong correlation to the TID up to 5 Mrad gamma irradiation as well. The improvement of charge retention loss for F-MOHOS devices is nearly 15% better than that of metal–oxide–hafnium oxide–oxide–silicon MOHOS devices. The F-MOHOS device described in this study demonstrates better feasibility for non-volatile TID radiation sensing in the future. PMID:27043560

  2. Performance differences in the detection of subgingival calculus by laser fluorescence devices.

    PubMed

    Shakibaie, Fardad; Walsh, Laurence J

    2015-12-01

    This study compared the performance of three laser fluorescence (LF) devices (DIAGNOdent Classic, DIAGNOdent Pen and KEY3 laser) under standardized laboratory conditions for detecting subgingival deposits of calculus on root surfaces of extracted teeth in typodonts. While some studies show the efficacy of LF devices for calculus detection compared with conventional periodontal probes, little is known regarding the differential performance of different LF devices. In this laboratory study, extracted teeth were set in an anatomical configuration in stone typodont models in a phantom head and impression material used to replicate periodontal soft tissues. A total of 240 sites were assessed on three occasions using the three different LF devices and results compared to direct microscopic examination of the roots of the extracted teeth under magnification. The KEY3 showed greater accuracy (86.4 %) than the DIAGNOdent Pen (84 %) and DIAGNOdent Classic (80.2 %). The intra-examiner reproducibility was also higher for the KEY3 (mean Cohen kappa 0.74) than the DIAGNOdent Pen (0.66) and DIAGNOdent Classic (0.6). Of the three LF devices, the KEY3 has greater accuracy and reproducibility. PMID:26396103

  3. Ion Implantation Angle Variation to Device Performance and the Control in Production

    SciTech Connect

    Zhao, Z.Y.; Hendrix, D.; Wu, L.Y.; Cusson, B.K.

    2003-08-26

    As the device features get smaller and aspect ratios of photoresist openings get steeper, shadowing effect has more impact on the performance of devices. Many of the traditional 7 deg. tilt implants have progressed to 0 deg. implants. But shadowing may still occur if the tilt angle deviates from normal direction. Some implants, such as halo implants, demand even more stringent angle control to reduce device performance variation. The demand for implant angle control and monitoring thus becomes more obvious and important. However, statistical process control (SPC) cannot be done on shadowing effect without special test structures. Channeling, on the other hand, provides good sensitivity in regard to implant angle changes. It is the authors' intention to introduce channeling implant in different channels to monitor the implant angle variation. The incoming <100> silicon wafers have a cut-angle spec of +/- 1.0 deg. This poses a difficulty if one wants to control the implant angle's accuracy within +/- 0.5 deg. Other measures have to be taken to ensure the consistency of test wafers and to have prompt diagnosis feedback when needed. This paper will discuss the effect of implant tilt angle on device parameters and how to control the angle variation in production. Correlations of implant tilt angle variation to ThermaWave, sheet resistance (Rs), Secondary Ion Mass Spectrometry (SIMS) and device parameters will be covered with certain implant conditions.

  4. Ion Implantation Angle Variation to Device Performance and the Control in Production

    NASA Astrophysics Data System (ADS)

    Zhao, Z. Y.; Hendrix, D.; Wu, L. Y.; Cusson, B. K.

    2003-08-01

    As the device features get smaller and aspect ratios of photoresist openings get steeper, shadowing effect has more impact on the performance of devices. Many of the traditional 7° tilt implants have progressed to 0° implants. But shadowing may still occur if the tilt angle deviates from normal direction. Some implants, such as halo implants, demand even more stringent angle control to reduce device performance variation. The demand for implant angle control and monitoring thus becomes more obvious and important. However, statistical process control (SPC) cannot be done on shadowing effect without special test structures. Channeling, on the other hand, provides good sensitivity in regard to implant angle changes. It is the authors' intention to introduce channeling implant in different channels to monitor the implant angle variation. The incoming <100> silicon wafers have a cut-angle spec of +/- 1.0°. This poses a difficulty if one wants to control the implant angle's accuracy within +/- 0.5°. Other measures have to be taken to ensure the consistency of test wafers and to have prompt diagnosis feedback when needed. This paper will discuss the effect of implant tilt angle on device parameters and how to control the angle variation in production. Correlations of implant tilt angle variation to ThermaWave™, sheet resistance (Rs), Secondary Ion Mass Spectrometry (SIMS) and device parameters will be covered with certain implant conditions.

  5. Pediatric hydrocephalus: Does the shunt device pressure selection affect the outcome?

    PubMed Central

    Sinha, Arvind; Sharma, Anuj; Gupta, Charitesh

    2012-01-01

    Aim: To compare the efficacy of low- versus medium-pressure shunts in pediatric hydrocephalus in a randomized controlled trial. Materials and Methods: Forty patients of pediatric hydrocephalus were randomized into two groups. The Chhabra differential pressure VP shunt (low or medium) was inserted in every patient. Postoperative follow-up was performed for symptomatic improvement and radiological evaluation (by sonography or computed tomography scan) for ventricle hemispheric ratio (VHR). Comparative analysis of pre- and postoperative VHR and need of redo surgery for shunt malformation were carried out to establish outcomes. Results: Nineteen patients had a low-pressure and 21 patients had a medium-pressure shunt inserted. The age of the patients ranged from 1 day to 10 years. The average preoperative VHR in group A was 55.37%, which reduced to 40% postoperatively (P = 0.00005); likewise, the pre- and postoperative VHR in group B were 61.57% and 42%, respectively, which was statistically significant (P = 0.0006). The complications of shunts and incidence of redo shunt surgery in both groups were not found to be statistically significant (P = 0.5614). Conclusions: The study found no significant difference in the outcome of patients with low- or medium-pressure shunt placement in pediatric hydrocephalus. PMID:22529548

  6. Electric-field enhanced performance in catalysis and solid-state devices involving gases

    SciTech Connect

    Blackburn, Bryan M.; Wachsman, Eric D.; Van Assche, IV, Frederick Martin

    2015-05-19

    Electrode configurations for electric-field enhanced performance in catalysis and solid-state devices involving gases are provided. According to an embodiment, electric-field electrodes can be incorporated in devices such as gas sensors and fuel cells to shape an electric field provided with respect to sensing electrodes for the gas sensors and surfaces of the fuel cells. The shaped electric fields can alter surface dynamics, system thermodynamics, reaction kinetics, and adsorption/desorption processes. In one embodiment, ring-shaped electric-field electrodes can be provided around sensing electrodes of a planar gas sensor.

  7. Performance Prediction of OWC Type Small Size Wave Power Device with Impulse Turbine

    NASA Astrophysics Data System (ADS)

    Suzuki, Masami; Takao, Manabu; Satoh, Eiji; Nagata, Shuichi; Toyota, Kazutaka; Setoguchi, Toshiaki

    This paper investigates a small size wave power device with an impulse turbine installed in the breakwater near Niigata Port, Japan. The device consists of an air chamber, a turbine, a generator and pressure-relief valves. This study reveals the characteristics of each component in this system with impulse turbine and a direct current dynamo the power of which is consumed by a constant resistor. In this paper special features of the impulse turbine are found, and the system characteristics are briefly represented. The overall plant performance was analyzed using mathematical model of an oscillating water column (OWC) based on linear water wave theory and the special features of the impulse turbine.

  8. Defining brain-machine interface applications by matching interface performance with device requirements.

    PubMed

    Tonet, Oliver; Marinelli, Martina; Citi, Luca; Rossini, Paolo Maria; Rossini, Luca; Megali, Giuseppe; Dario, Paolo

    2008-01-15

    Interaction with machines is mediated by human-machine interfaces (HMIs). Brain-machine interfaces (BMIs) are a particular class of HMIs and have so far been studied as a communication means for people who have little or no voluntary control of muscle activity. In this context, low-performing interfaces can be considered as prosthetic applications. On the other hand, for able-bodied users, a BMI would only be practical if conceived as an augmenting interface. In this paper, a method is introduced for pointing out effective combinations of interfaces and devices for creating real-world applications. First, devices for domotics, rehabilitation and assistive robotics, and their requirements, in terms of throughput and latency, are described. Second, HMIs are classified and their performance described, still in terms of throughput and latency. Then device requirements are matched with performance of available interfaces. Simple rehabilitation and domotics devices can be easily controlled by means of BMI technology. Prosthetic hands and wheelchairs are suitable applications but do not attain optimal interactivity. Regarding humanoid robotics, the head and the trunk can be controlled by means of BMIs, while other parts require too much throughput. Robotic arms, which have been controlled by means of cortical invasive interfaces in animal studies, could be the next frontier for non-invasive BMIs. Combining smart controllers with BMIs could improve interactivity and boost BMI applications. PMID:17499364

  9. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET

    PubMed Central

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  10. Device and circuit-level performance of carbon nanotube field-effect transistor with benchmarking against a nano-MOSFET.

    PubMed

    Tan, Michael Loong Peng; Lentaris, Georgios; Amaratunga Aj, Gehan

    2012-01-01

    The performance of a semiconducting carbon nanotube (CNT) is assessed and tabulated for parameters against those of a metal-oxide-semiconductor field-effect transistor (MOSFET). Both CNT and MOSFET models considered agree well with the trends in the available experimental data. The results obtained show that nanotubes can significantly reduce the drain-induced barrier lowering effect and subthreshold swing in silicon channel replacement while sustaining smaller channel area at higher current density. Performance metrics of both devices such as current drive strength, current on-off ratio (Ion/Ioff), energy-delay product, and power-delay product for logic gates, namely NAND and NOR, are presented. Design rules used for carbon nanotube field-effect transistors (CNTFETs) are compatible with the 45-nm MOSFET technology. The parasitics associated with interconnects are also incorporated in the model. Interconnects can affect the propagation delay in a CNTFET. Smaller length interconnects result in higher cutoff frequency. PMID:22901374

  11. Optimization of Metal Oxides Thickness and Related Organic Electroluminescent Device Performance.

    PubMed

    Chiu, Tien-Lung; Chuang, Ya-Ting

    2015-11-01

    In this study, three commercial transition metal oxides such as molybdenum trioxide (MoO3), tungsten trioxide (WO3), and vanadium pent-oxide (V2O5) were employed as hole-injection layer to improve the electrical and optical performance of organic light-emitting diodes (OLEDs). The layer thickness of MoO3, WO3 and V2O5 were respectively varied by 1, 2, 5 and 10 nm inside blue OLED to characterize their effects on device performance. The optimal OLED with a 5 nm MoO3 hole-injection layer performs an enhancement of 12.9% in current efficiency, 17.5% in power efficiency and 9.3% in maximum external quantum efficiency, comparing to that of reference device without hole-injection layer. PMID:26726669

  12. Performance Assessment in CTE: Focusing on the Cognitive, Psychomotor ...and Affective Domains

    ERIC Educational Resources Information Center

    Washer, Bart; Cochran, Lori

    2012-01-01

    When a student is performing in the psychomotor domain, the authors believe the student is also performing in the cognitive domain (sequencing steps, evaluating the situation) and in the affective domain (appreciating a job well done, quality control, safety). As Dabney Doty, former instructor at the University of Central Missouri, stated, "There…

  13. The Developmental Dynamics of Children's Academic Performance and Mothers' Homework-Related Affect and Practices

    ERIC Educational Resources Information Center

    Silinskas, Gintautas; Kiuru, Noona; Aunola, Kaisa; Lerkkanen, Marja-Kristiina; Nurmi, Jari-Erik

    2015-01-01

    This study investigated the longitudinal associations between children's academic performance and their mothers' affect, practices, and perceptions of their children in homework situations. The children's (n = 2,261) performance in reading and math was tested in Grade 1 and Grade 4, and the mothers (n = 1,476) filled out questionnaires on their…

  14. Centrality and Charisma: Comparing How Leader Networks "and" Attributions Affect Team Performance

    ERIC Educational Resources Information Center

    Balkundi, Prasad; Kilduff, Martin; Harrison, David A.

    2011-01-01

    When leaders interact in teams with their subordinates, they build social capital that can have positive effects on team performance. Does this social capital affect team performance because subordinates come to see the leader as charismatic? We answered this question by examining 2 models. First, we tested the charisma-to-centrality model…

  15. Some Factors That Affecting the Performance of Mathematics Teachers in Junior High School in Medan

    ERIC Educational Resources Information Center

    Manullang, Martua; Rajagukguk, Waminton

    2016-01-01

    Some Factor's That Affecting The Mathematic Teacher Performance For Junior High School In Medan. This research will examine the effect of direct and indirect of the Organizational Knowledge towards the achievement motivation, decision making, organizational commitment, the performance of mathematics teacher. The research method is a method of…

  16. The developmental dynamics of children's academic performance and mothers' homework-related affect and practices.

    PubMed

    Silinskas, Gintautas; Kiuru, Noona; Aunola, Kaisa; Lerkkanen, Marja-Kristiina; Nurmi, Jari-Erik

    2015-04-01

    This study investigated the longitudinal associations between children's academic performance and their mothers' affect, practices, and perceptions of their children in homework situations. The children's (n = 2,261) performance in reading and math was tested in Grade 1 and Grade 4, and the mothers (n = 1,476) filled out questionnaires on their affect, practices, and perceptions while their children were in Grades 2, 3, and 4. The results showed, first, that the more help in homework the mothers reported, the slower was the development of their children's academic performance from Grade 1 to Grade 4. This negative association was true especially if mothers perceived their children not to be able to work autonomously. Second, children's good academic performance in Grade 1 predicted mothers' perception of child's ability to be autonomous and positive affect in homework situations later on, whereas poor performance predicted mothers' negative affect, help, and monitoring. Finally, mothers' negative affect mediated the association between children's poor performance, maternal practices, and perceptions of their children. PMID:25798959

  17. High-performing nonlinear visualization of terahertz radiation on a silicon charge-coupled device

    PubMed Central

    Shalaby, Mostafa; Vicario, Carlo; Hauri, Christoph P.

    2015-01-01

    Photoinduced electron transitions can lead to significant changes of the macroscopic electronic properties in semiconductors. This principle is responsible for the detection of light with charge-coupled devices. Their spectral sensitivity is limited by the semiconductor bandgap which has restricted their visualization capabilities to the optical, ultraviolet, and X-ray regimes. The absence of an imaging device in the low frequency terahertz range has severely hampered the advance of terahertz imaging applications in the past. Here we introduce a high-performing imaging concept to the terahertz range. On the basis of a silicon charge-coupled device we visualize 5–13 THz radiation with photon energy under 2% of the sensor's band-gap energy. The unprecedented small pitch and large number of pixels allow the visualization of complex terahertz radiation patterns in real time and with high spatial detail. This advance will have a great impact on a wide range of terahertz imaging disciplines. PMID:26496973

  18. SEMICONDUCTOR DEVICES: A high-performance enhancement-mode AlGaN/GaN HEMT

    NASA Astrophysics Data System (ADS)

    Zhihong, Feng; Shengyin, Xie; Rui, Zhou; Jiayun, Yin; Wei, Zhou; Shujun, Cai

    2010-08-01

    An enhancement-mode AlGaN/GaN HEMT with a threshold voltage of 0.35 V was fabricated by fluorine plasma treatment. The enhancement-mode device demonstrates high-performance DC characteristics with a saturation current density of 667 mA/mm at a gate bias of 4 V and a peak transconductance of 201 mS/mm at a gate bias of 0.8 V. The current-gain cut-off frequency and the maximum oscillation frequency of the enhancement-mode device with a gate length of 1 μm are 10.3 GHz and 12.5 GHz, respectively, which is comparable with the depletion-mode device. A numerical simulation supported by SIMS results was employed to give a reasonable explanation that the fluorine ions act as an acceptor trap center in the barrier layer.

  19. Best-case performance of quantum annealers on native spin-glass benchmarks: How chaos can affect success probabilities

    NASA Astrophysics Data System (ADS)

    Zhu, Zheng; Ochoa, Andrew J.; Schnabel, Stefan; Hamze, Firas; Katzgraber, Helmut G.

    2016-01-01

    Recent tests performed on the D-Wave Two quantum annealer have revealed no clear evidence of speedup over conventional silicon-based technologies. Here we present results from classical parallel-tempering Monte Carlo simulations combined with isoenergetic cluster moves of the archetypal benchmark problem—an Ising spin glass—on the native chip topology. Using realistic uncorrelated noise models for the D-Wave Two quantum annealer, we study the best-case resilience, i.e., the probability that the ground-state configuration is not affected by random fields and random-bond fluctuations found on the chip. We thus compute classical upper-bound success probabilities for different types of disorder used in the benchmarks and predict that an increase in the number of qubits will require either error correction schemes or a drastic reduction of the intrinsic noise found in these devices. We restrict this study to the exact ground state, however, the approach can be trivially extended to the inclusion of excited states if the success metric is relaxed. We outline strategies to develop robust, as well as hard benchmarks for quantum annealing devices, as well as any other (black box) computing paradigm affected by noise.

  20. Performance and Characterization of Magnetic Penetration Thermometer Devices for X-Ray Spectroscopy

    NASA Technical Reports Server (NTRS)

    Porst, J. -P.; Adams, J. S.; Bandler, S. R.; Balvin, M.; Busch, S. E.; Denis, K. L.; Kelly, D.; Nagler, P.; Sadleir, J. E.; Seidel, G. M.; Smith, S.; Stevenson, T. R.

    2012-01-01

    We are developing magnetic penetration thermometers (MPTs) for applications in X-ray astronomy. These non-dissipative devices consist of an X-ray absorber in good thermal contact to a superconducting thin film with a transition temperature around T=100mK. A microfabricated superconducting planar inductor underneath is used to store a persistent current and couple the superconductor's diamagnetic response to a readout SQUID. The strong temperature dependence of the diamagnetic response make these devices suitable for highly sensitive macroscopic thermometers that are capable of achieving very high energy resolution. We present results achieved with MPTs consisting of MoAu bilayer sensors attached to overhanging square 250 micron by 250 micron gold absorbers that have demonstrated an energy resolution of delta E_FWHM=2.3eV at an X-ray energy of 5.9keV. A similar device has shown delta E_FWHM=2.0eV at 1.5 keV. Under certain conditions and for specific device geometries, the temperature responsivity of the MPTs can vary on long timescales degrading the spectral performance. We present the characterization of different inductor geometries to optimize the design for the highest possible temperature sensitivity and compare different device designs with respect to responsivity stability.

  1. Performance improvement of rubrene-based organic light emitting devices with a mixed single layer

    NASA Astrophysics Data System (ADS)

    Wang, Zhaokui; Naka, Shigeki; Okada, Hiroyuki

    2010-09-01

    We have investigated the performance of organic light-emitting devices (OLEDs) with a rubrene-doped mixed single layer by using 4,4'-bis[N-(1-napthyl)-N-phenyl- amion] biphenyl ( α-NPD) as hole transport layer. Comparing to a conventional heterostructure OLED, equal luminance vs. current density characteristics were obtained. In addition, maximum power efficiency was threefold improved, and the achieved value was 5.90 lm/W by optimizing a mixing ratio of hole and electron transport materials. By evaluating the temperature dependence of the J - V characteristics for electron-injection dominated device, the electron injection from Al/LiF to mixed organic layer is attributed to Schottky thermal emission model. And the barrier height of the electron injection from Al/LiF into mixed single layer was obtained to be 0.62 eV, which is lower than Al/Alq3 interface. Meanwhile, the mixed single-layer device exhibited superior operational durability at a half-luminance of 2,250 h under a constant current operation mode. The reliability was improved with a factor of two compared to the heterostructure device due to the improvement of stability in mixed organic molecules and removal of the heterojunction interface in the mixed single-layer device.

  2. High-performance UV-curable epoxy resin-based microarray and microfluidic immunoassay devices.

    PubMed

    Yu, Ling; Liu, Yingshuai; Gan, Ye; Li, Chang Ming

    2009-06-15

    Immunoassay devices including microarray and microfluidic systems were fabricated with an UV-curable resin by a new economic approach, which can not only simply produce a 3-dimensional (3D) patterned structure, but also simultaneously introduce functional epoxide groups for efficient protein immobilization. The performance of the epoxy resin-based microarray was improved by optimization of printing buffer, probe concentration, and immobilization time, showing a detection dynamic range of 5 orders of magnitude and a limit of detection (LOD) of 10 pg mL(-1) for immunoglobulin G (IgG). The developed microfluidic immunoassay device demonstrates a LOD of 100 pg mL(-1) for IL-5 detection. The device can also be used to colorimetrically detect proteins via naked human eyes for immunoassays. This work provides a simple and inexpensive method to fabricate a sensitive immunoassay device, especially a 3D microfluidic system, which has great potential to develop a portable immunoassay device via human eye detection for point-of-care service and/or high throughput screening of infectious diseases. PMID:19346122

  3. Assessment of v-gel supraglottic airway device placement in cats performed by inexperienced veterinary students.

    PubMed

    Barletta, M; Kleine, S A; Quandt, J E

    2015-11-21

    Endotracheal intubation has been associated with several complications in cats. The v-gel supraglottic airway device (SGAD) has been developed to adapt to the unique oropharynx of the cat and to overcome these complications. Thirty-three cats were randomly assigned to receive an endotracheal tube (ETT group) or a v-gel SGAD (v-gel group) after induction of general anaesthesia. Third year veterinary students without previous clinical experience placed these devices under direct supervision of an anaesthesiologist. Amount of propofol, number of attempts, time required to secure the airway, leakage around the device, signs of upper airway discomfort and food consumption were compared between the two groups. The v-gel group required less propofol (P=0.03), less time (P<0.01) and fewer attempts (P<0.01) to secure the cats' airway. The incidence of leakage was lower for the v-gel group immediately after placement of the device (P<0.01) and 60 minutes after induction of general anaesthesia (P=0.04). Cats that received the v-gel SGAD presented a lower incidence of upper airway discomfort immediately after the device was removed (P=0.03) and recorded a higher food consumption score (P=0.03). The v-gel SGAD is a feasible way to secure the airway of healthy cats when performed by inexperienced personnel. PMID:26543177

  4. Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius).

    PubMed

    Penning, David A; Dartez, Schuyler F

    2016-03-01

    Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction pressure is affected by snake size, sex, and experience. In one experiment, we tested the ontogenetic scaling of constriction performance and found that snake diameter was the only significant factor determining peak constriction pressure. The number of loops applied in a coil and its interaction with snake diameter did not significantly affect constriction performance. Constriction performance in ball pythons scaled differently than in other snakes that have been studied, and medium to large ball pythons are capable of exerting significantly higher pressures than those shown to cause circulatory arrest in prey. In a second experiment, we tested the effects of experience on constriction performance in hatchling ball pythons over 10 feeding events. By allowing snakes in one test group to gain constriction experience, and manually feeding snakes under sedation in another test group, we showed that experience did not affect constriction performance. During their final (10th) feedings, all pythons constricted similarly and with sufficiently high pressures to kill prey rapidly. At the end of the 10 feeding trials, snakes that were allowed to constrict were significantly smaller than their non-constricting counterparts. J. Exp. Zool. 9999A:XX-XX, 2016. © 2016 Wiley Periodicals, Inc. PMID:26847931

  5. Improvement of device performance of polymer organic light-emitting diodes on smooth transparent sheet with graphene films synthesized by plasma treatment

    NASA Astrophysics Data System (ADS)

    Okigawa, Yuki; Mizutani, Wataru; Suzuki, Kenkichi; Ishihara, Masatou; Yamada, Takatoshi; Hasegawa, Masataka

    2015-09-01

    Because graphene films have one-atom thickness, the morphology of the transparent sheets could have a greater effect on the performance of organic light-emitting diode (OLED) devices with graphene films than on that with indium tin oxide (ITO). In this study, we have evaluated the polymer OLED devices with graphene films synthesized by plasma treatment on poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN) sheets having high flatness. The results imply that the surface roughness of the transparent sheets predominantly affects the luminescence of polymer OLED devices with graphene films. The suppression of leakage current and a luminescence higher than 8000 cd/m2 at 15 V were attained for the devices on the transparent sheet with higher flatness in spite of the presence of large sharp spikes.

  6. Performance analysis of resistive switching devices based on BaTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Samardzic, Natasa; Kojic, Tijana; Vukmirovic, Jelena; Tripkovic, Djordjije; Bajac, Branimir; Srdic, Vladimir; Stojanovic, Goran

    2016-03-01

    Resitive switching devices, memristors, have recenty attracted much attention due to promising performances and potential applications in the field of logic and memory devices. Here, we present thin film BaTiO3 based memristor fabricated using ink-jet printing technique. Active material is a single layer barium titanate film with thickness of ̴100 nm, sandwitched between metal electodes. Printing parameters were optimized aiming to achieve stable drop flow and uniform printed layer. Current-voltage characteristics show typical memristive behavior with pinched hysteresis loop crossed at the origin, with marked differences between High Resistive State (HRS) and Low Resistive State (LRS). Obtained resistive states are stable during numerous switching processes. The device also shows unipolar switching effect for negative voltage impulses. Variable voltage impulse amplitudes leads to the shifting of the energy levels of electode contacts resulting in changing of the overall current through the device. Structural charcterization have been performed using XRD analysis and SEM micrography. High-temperature current-voltage measurements combined with transport parameter analysis using Hall efect measurement system (HMS 3000) and Impedance Analyzer AC measurements allows deeper insigth into conduction mechanism of ferroelectric memristors.

  7. A review of performance of near-infrared fluorescence imaging devices used in clinical studies

    PubMed Central

    Zhu, B

    2015-01-01

    Near-infrared fluorescence (NIRF) molecular imaging holds great promise as a new “point-of-care” medical imaging modality that can potentially provide the sensitivity of nuclear medicine techniques, but without the radioactivity that can otherwise place limitations of usage. Recently, NIRF imaging devices of a variety of designs have emerged in the market and in investigational clinical studies using indocyanine green (ICG) as a non-targeting NIRF contrast agent to demark the blood and lymphatic vasculatures both non-invasively and intraoperatively. Approved in the USA since 1956 for intravenous administration, ICG has been more recently used off label in intradermal or subcutaneous administrations for fluorescence imaging of the lymphatic vasculature and lymph nodes. Herein, we summarize the devices of a variety of designs, summarize their performance in lymphatic imaging in a tabular format and comment on necessary efforts to develop standards for device performance to compare and use these emerging devices in future, NIRF molecular imaging studies. PMID:25410320

  8. In vivo performance of a matrix-based quantitative ultrasound imaging device dedicated to calcaneus investigation.

    PubMed

    Gomez, M A; Defontaine, M; Giraudeau, B; Camus, E; Colin, L; Laugier, P; Patat, F

    2002-10-01

    We developed a prototype of an ultrasound (US) bone matrix densitometer, the BEAM scanner, in the context of a European Space Agency research program. This device, which is a contact imaging device, was designed to overcome the limitations of immersion devices in space. Broadband US attenuation (BUA) and speed of sound (SOS) parameters were calculated from the radiofrequency (RF) signal. The principle aim of this study was to evaluate in vivo performance in direct comparison with a currently available device (UBIS 3000, DMS, France). The short-term precision of the BEAM scanner for BUA was estimated at 2.8%, whereas it was 2.3% with UBIS 3000. The short-term precision for SOS was 0.3%, and this was the same as the coefficient of variation (CV) of the UBIS 3000. CVs of 3.4% and 0.6% for midterm precision were found for BUA and SOS, respectively, and UBIS 3000 scores were 3% and 0.4%, respectively. This preliminary study demonstrates the high performance of the BEAM scanner and its new concept offers a wide range of improvements and new applications. PMID:12467855

  9. Surface acoustic wave nebulization device with dual interdigitated transducers improves SAWN-MS performance.

    PubMed

    Huang, Yue; Heron, Scott R; Clark, Alicia M; Edgar, J Scott; Yoon, Sung Hwan; Kilgour, David P A; Turecek, Frantisek; Aliseda, Alberto; Goodlett, David R

    2016-06-01

    We compared mass spectrometric (MS) performance of surface acoustic wave nebulization (SAWN) generated by a single interdigitated transducer (IDT) designed to produce a progressive wave (PW) to one with a dual IDT that can in theory generate standing waves (SW). Given that devices using dual IDTs had been shown to produce fewer large size droplets on average, we hypothesized they would improve MS performance by improving the efficiency of desolvation. Indeed, the SW-SAWN chip provided an improved limit of detection of 1 femtomole of peptide placed on chip making it 100× more sensitive than the PW design. However, as measured by high-speed image recording and phase Doppler particle analyzer measurements, there was only a 26% increase in the small diameter (1-10 µm) droplets produced from the new device, precluding a conclusion that the decrease in droplet size was solely responsible for the improvement in MS signal/noise. Given that the dual IDT design produced a more instantaneous plume than the PW design, the more likely contributor to improved MS signal/noise was concluded to be a higher ion flux entering the mass spectrometer for the dual IDT designs. Notably, the dual IDT device allowed production of much higher quality protein mass spectra up to about 20 kDa, compared with the single IDT device. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27270865

  10. Retrofit device to improve vapor compression cooling system performance by dynamic blower speed modulation

    DOEpatents

    Roth, Robert Paul; Hahn, David C.; Scaringe, Robert P.

    2015-12-08

    A device and method are provided to improve performance of a vapor compression system using a retrofittable control board to start up the vapor compression system with the evaporator blower initially set to a high speed. A baseline evaporator operating temperature with the evaporator blower operating at the high speed is recorded, and then the device detects if a predetermined acceptable change in evaporator temperature has occurred. The evaporator blower speed is reduced from the initially set high speed as long as there is only a negligible change in the measured evaporator temperature and therefore a negligible difference in the compressor's power consumption so as to obtain a net increase in the Coefficient of Performance.

  11. Novel methodology to determine thermal conductivity of thermoelectric materials and comparison with device performance

    NASA Astrophysics Data System (ADS)

    Maddux, Jay R.; Taylor, Patrick J.

    2012-06-01

    Accuracy of thermal conductivity measurements is an ongoing area of controversy in thermoelectric materials development. In this work, we demonstrate a novel steady-state method for characterizing thermal conductivity of bulk materials and devices under isothermal and near-isothermal conditions. The isothermal condition is achieved by exactly balancing Peltier heat flow against an externally imposed heat flow in the material. Under steady-state, isothermal conditions, heat flow in the material can be determined with high accuracy because external parasitic heat flows become negligible. We compare our results with conventional measurement techniques and also with measured thermoelectric device performance. Agreement between predicted and measured thermoelectric cooler performance is within 2%. Results for thermoelectric power generators will also be discussed.

  12. Maternal affection moderates the impact of psychological control on a child's mathematical performance.

    PubMed

    Aunola, Kaisa; Nurmi, Jari-Erik

    2004-11-01

    This study investigated the extent to which mothers' psychological control predicts their children's mathematical performance during the children's transition from preschool to primary school over and above the impact of maternal affection and behavioral control. Also investigated was the extent to which maternal affection and behavioral control moderate the impact of mothers' psychological control. Children 5-6 years old at baseline (N=196) were followed up 6 times to measure their performance in mathematics over a 3-year period from preschool to 2nd grade. Mothers were asked to fill in a questionnaire measuring their parenting styles once every year over the 3-year period. A high level of psychological control exercised by mothers predicted their children's slow progress in mathematics. However, this impact was particularly evident among those children whose mothers reported a high level of affection. No evidence was found that children's mathematical performance had any effect on their mothers' parenting styles. PMID:15535751

  13. Boosting the Performance of Organic Optoelectronic Devices Using Multiple-Patterned Plasmonic Nanostructures.

    PubMed

    Lee, Yoon Ho; Lee, Tae Kyung; Song, Inho; Yu, Hojeong; Lee, Jiwon; Ko, Hyunhyub; Kwak, Sang Kyu; Oh, Joon Hak

    2016-07-01

    Multiple-patterned nanostructures prepared by synergistically combining block-copolymer lithography with nano-imprinting lithography have been used as back reflectors for enhancing light absorption in organic optoelectronic devices. The multiple-patterned electrodes have significantly boosted the performance of organic photovoltaics and photo-transistors, owed to the highly effective light scattering and plasmonic effects, extending the range of their practical applications. PMID:27146332

  14. A review of published quantitative experimental studies on factors affecting laboratory fume hood performance.

    PubMed

    Ahn, Kwangseog; Woskie, Susan; DiBerardinis, Louis; Ellenbecker, Michael

    2008-11-01

    This study attempted to identify the important factors that affect the performance of a laboratory fume hood and the relationship between the factors and hood performance under various conditions by analyzing and generalizing the results from other studies that quantitatively investigated fume hood performance. A literature search identified 43 studies that were published from 1966 to 2006. For each of those studies, information on the type of test methods used, the factors investigated, and the findings were recorded and summarized. Among the 43 quantitative experimental studies, 21 comparable studies were selected, and then a meta-analysis of the comparable studies was conducted. The exposure concentration variable from the resulting 617 independent test conditions was dichotomized into acceptable or unacceptable using the control level of 0.1 ppm tracer gas. Regression analysis using Cox proportional hazards models provided hood failure ratios for potential exposure determinants. The variables that were found to be statistically significant were the presence of a mannequin/human subject, the distance between a source and breathing zone, and the height of sash opening. In summary, performance of laboratory fume hoods was affected mainly by the presence of a mannequin/human subject, distance between a source and breathing zone, and height of sash opening. Presence of a mannequin/human subject in front of the hood adversely affects hood performance. Worker exposures to air contaminants can be greatly reduced by increasing the distance between the contaminant source and breathing zone and by reducing the height of sash opening. Many other factors can also affect hood performance. Checking face velocity by itself is unlikely to be sufficient in evaluating hood performance properly. An evaluation of the performance of a laboratory fume hood should be performed with a human subject or a mannequin in front of the hood and should address the effects of the activities

  15. Effect of Mesostructured Layer upon Crystalline Properties and Device Performance on Perovskite Solar Cells.

    PubMed

    Listorti, Andrea; Juarez-Perez, Emilio J; Frontera, Carlos; Roiati, Vittoria; Garcia-Andrade, Laura; Colella, Silvia; Rizzo, Aurora; Ortiz, Pablo; Mora-Sero, Ivan

    2015-05-01

    One of the most fascinating characteristics of perovskite solar cells (PSCs) is the retrieved obtainment of outstanding photovoltaic (PV) performances withstanding important device configuration variations. Here we have analyzed CH3NH3PbI3-xClx in planar or in mesostructured (MS) configurations, employing both titania and alumina scaffolds, fully infiltrated with perovskite material or presenting an overstanding layer. The use of the MS scaffold induces to the perovskite different structural properties, in terms of grain size, preferential orientation, and unit cell volume, in comparison to the ones of the material grown with no constraints, as we have found out by X-ray diffraction analyses. We have studied the effect of the PSC configuration on photoinduced absorption and time-resolved photoluminescence, complementary techniques that allow studying charge photogeneration and recombination. We have estimated electron diffusion length in the considered configurations observing a decrease when the material is confined in the MS scaffold with respect to a planar architecture. However, the presence of perovskite overlayer allows an overall recovering of long diffusion lengths explaining the record PV performances obtained with a device configuration bearing both the mesostructure and a perovskite overlayer. Our results suggest that performance in devices with perovskite overlayer is mainly ruled by the overlayer, whereas the mesoporous layer influences the contact properties. PMID:26263326

  16. Performance Measurement of a Multi-Level/Analog Ferroelectric Memory Device Design

    NASA Technical Reports Server (NTRS)

    MacLeod, Todd C.; Phillips, Thomas A.; Ho, Fat D.

    2007-01-01

    Increasing the memory density and utilizing the unique characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes the characterization of a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used a reference to determinethe amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. This paper presents measurements of an actual prototype memory cell. This prototype is not a complete implementation of a device, but instead, a prototype of the storage and retrieval portion of an actual device. The performance of this prototype is presented with the projected performance of the overall device. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.

  17. On the role of positive and negative affectivity in job performance: a meta-analytic investigation.

    PubMed

    Kaplan, Seth; Bradley, Jill C; Luchman, Joseph N; Haynes, Douglas

    2009-01-01

    Although interest regarding the role of dispositional affect in job behaviors has surged in recent years, the true magnitude of affectivity's influence remains unknown. To address this issue, the authors conducted a qualitative and quantitative review of the relationships between positive and negative affectivity (PA and NA, respectively) and various performance dimensions. A series of meta-analyses based on 57 primary studies indicated that PA and NA predicted task performance in the hypothesized directions and that the relationships were strongest for subjectively rated versus objectively rated performance. In addition, PA was related to organizational citizenship behaviors but not withdrawal behaviors, and NA was related to organizational citizenship behaviors, withdrawal behaviors, counterproductive work behaviors, and occupational injury. Mediational analyses revealed that affect operated through different mechanisms in influencing the various performance dimensions. Regression analyses documented that PA and NA uniquely predicted task performance but that extraversion and neuroticism did not, when the four were considered simultaneously. Discussion focuses on the theoretical and practical implications of these findings. (PsycINFO Database Record (c) 2009 APA, all rights reserved). PMID:19186902

  18. Developments in the design and performance of IR scene projector devices at BAE Systems

    NASA Astrophysics Data System (ADS)

    Pritchard, Alan P.; Balmond, Mark D.; Venables, Mark A.; Lake, Stephen P.

    2000-07-01

    The status of development of resistor-array infra-red scene projector devices at BAE SYSTEMS is that two variants of a 512 X 512 array have each been brought to a second development stage, whilst work on higher complexity arrays is slow but purposeful. In this paper we describe the latest features of the 512 arrays, exhibiting on the one hand high fidelity performance through a ballast-load configuration, and on the other hand very high apparent temperature output, coupled with high speed performance. For higher complexity arrays we describe some of the system philosophy and preliminary design work.

  19. Comparative Study on the Performance of Five Different Hall Effect Devices

    PubMed Central

    Paun, Maria-Alexandra; Sallese, Jean-Michel; Kayal, Maher

    2013-01-01

    Five different Hall Effect sensors were modeled and their performance evaluated using a three dimensional simulator. The physical structure of the implemented sensors reproduces a certain technological fabrication process. Hall voltage, absolute, current-related, voltage-related and power-related sensitivities were obtained for each sensor. The effect of artificial offset was also investigated for cross-like structures. The simulation procedure guides the designer in choosing the Hall cell optimum shape, dimensions and device polarization conditions that would allow the highest performance. PMID:23385419

  20. Malaysian and Singaporean students' affective characteristics and mathematics performance: evidence from PISA 2012.

    PubMed

    Thien, Lei Mee; Ong, Mei Yean

    2015-01-01

    This paper attempts to identify the extent to which the affective characteristics of Malaysian and Singaporean students' attainment compared to the OECD average in Programme for International Student Assessment (PISA) 2012, and examine the influence of students' affective characteristics, gender, and their socioeconomic status on mathematics performance at both student and school levels. Sample consisted of 5197 and 5546 15-year-old Malaysian and Singaporean students. Data were analysed using hierarchical linear modelling approach with HLM 7.0 software. Results showed that the Index of economic, social, and cultural status (ESCS), mathematics self-efficacy, and mathematics anxiety have significant effects on mathematics performance in Malaysia and Singapore at the student level. Proportion of boys at the school level has no significant effects on mathematics performance for both Malaysian and Singaporean students. ESCS mean at the school level has positive and significant effects on mathematics performance in Malaysia, but not in Singapore. Limitations, implications, and future studies were discussed. PMID:26543698

  1. Impact of fMRI Scanner Noise on Affective State and Attentional Performance

    PubMed Central

    Jacob, Shawna N.; Shear, Paula K.; Norris, Matthew; Smith, Matthew; Osterhage, Jeff; Strakowski, Stephen M.; Cerullo, Michael; Fleck, David E.; Lee, Jing-Huei; Eliassen, James C.

    2015-01-01

    Introduction Previous research has shown that performance on cognitive tasks administered in the scanner can be altered by the scanner environment. There are no previous studies that have investigated the impact of scanner noise using a well-validated measure of affective change. The goal of this study was to determine whether performance on an affective attentional task or emotional response to the task would change in the presence of distracting acoustic noise, such as that encountered in an MRI environment. Method Thirty-four young adults with no self-reported history of neurologic disorder or mental illness completed three blocks of the affective Posner task outside of the scanner. The task was meant to induce frustration through monetary contingencies and rigged feedback. Participants completed a self-assessment manikin at the end of each block to rate their mood, arousal level, and sense of dominance. During the task, half of the participants heard noise (recorded from a 4T MRI system), and half heard no noise. Results The affective Posner task led to significant reductions in mood and increases in arousal in healthy participants. The presence of scanner noise did not impact task performance; however, individuals in the noise group did report significantly poorer mood throughout the task. Conclusions The results of the present study suggest that the acoustic qualities of MRI enhance frustration effects on an affective attentional task and that scanner noise may influence mood during similar fMRI tasks. PMID:26059389

  2. Oral impacts affecting daily performance in a low dental disease Thai population.

    PubMed

    Adulyanon, S; Vourapukjaru, J; Sheiham, A

    1996-12-01

    The aim of the study was to measure incidence of oral impacts on daily performances and their related features in a low dental disease population. 501 people aged 35-44 years in 16 rural villages in Ban Phang district, Khon Kaen, Thailand, were interviewed about oral impacts on nine physical, psychological and social aspects of performance during the past 6 months, and then had an oral examination. The clinical and behavioural data showed that the sample had low caries (DMFT = 2.7) and a low utilization of dental services. 73.6% of all subjects had at least one daily performance affected by an oral impact. The highest incidence of performances affected were Eating (49.7%), Emotional stability (46.5%) and Smiling (26.1%). Eating, Emotional stability and Cleaning teeth performances had a high frequency or long duration of impacts, but a low severity. The low frequency performances; Physical activities, Major role activity and Sleeping were rated as high severity. Pain and discomfort were mainly perceived as the causes of impacts (40.1%) for almost every performance except Smiling. Toothache was the major causal oral condition (32.7%) of almost all aspects of performance. It was concluded that this low caries people have as high an incidence of oral impacts as industrialized, high dental disease populations. Frequency and severity presented the paradoxical effect on different performances and should both be taken into account for overall estimation of impacts. PMID:9007354

  3. Alpha suppression following performance errors is correlated with depression, affect, and coping behaviors.

    PubMed

    Compton, Rebecca J; Hofheimer, Julia; Kazinka, Rebecca; Levinson, Amanda; Zheutlin, Amanda

    2013-10-01

    This study tested the hypothesis that enhanced neural arousal in response to performance errors would predict poor affect and coping behaviors in everyday life. Participants were preselected as either low-depressed (LD) or high-depressed (HD) based on a screening questionnaire, and they then completed a laboratory Stroop task while EEG was recorded, followed by a 2-week period of daily reports of affect and coping behaviors. The EEG measure of arousal response to errors was the degree of error-related alpha suppression (ERAS) in the intertrial interval, that is the reduction in alpha power following errors compared with correct responses. ERAS was relatively heightened at frontal sites for the HD versus the LD group, and frontal ERAS predicted lower positive affect, higher negative affect, and less adaptive coping behaviors in the daily reports. Together, the results imply that heightened arousal following mistakes is associated with suboptimal emotion and coping with stressors. PMID:23731439

  4. Improved device bonding performance: precise placement with appropriate thermal and atmospheric control

    NASA Astrophysics Data System (ADS)

    Avila, Robert; McLeod, Saul

    2009-02-01

    In any assembly, where two devices are to be precisely connected, the integrity and quality of this connection (bond) is a key factor in the overall performance of the final device. In micro-assembly and optoelectronics, this connection is typically gold to gold, solder, or epoxy bond. The chemistries can vary, but the critical issues remain the same. Placement accuracy is an important consideration and is normally the starting point for most bonding applications. In optoelectronics, the placement of a laser will be critical to its performance. Often edge-to-edge alignment is needed, which requires optical resolution of one micron or better. Laser bars have the added challenge of requiring this high optical resolution, but over distances of more than 10 millimeters. Equally important is what happens after a device has been aligned to a substrate ready for bonding. Both thermal and force parameters must be considered. Voiding in the material or oxidation during the soldering process all need to be minimized. This paper will look at recent innovations to improve the final bond. These innovations include temperature ramp rate, heated inert atmosphere and component uniformity. These processing techniques are particularly applicable in optoelectronics applications, such as laser diode and laser bar bonding.

  5. ULTRAFINE CARBON PARTICLE (UFCP) INHALATION AFFECTS CARDIOVASCULAR PERFORMANCE IN HYPERTENSIVE RATS (SHR)

    EPA Science Inventory

    Inhaled UfCP affect cardiovascular performance in healthy rats (Harder et al. Inhal Toxicol 2005; 17:29-42) without apparent pulmonary damage. To assess whether geriatric cardiovascular compromised rats are more susceptible to UfCP effects, male adult (6months) and geriatric (13m...

  6. Internal Challenges Affecting Academic Performance of Student-Athletes in Ghanaian Public Universities

    ERIC Educational Resources Information Center

    Apaak, Daniel; Sarpong, Emmanuel Osei

    2015-01-01

    This paper examined internal challenges affecting academic performance of student-athletes in Ghanaian public universities, using a descriptive survey research design. Proportionate random sampling technique was employed to select Three Hundred and Thirty-Two (332) respondents for the study. The instrument used in gathering data for the study was…

  7. Factors Affecting Business Students' Performance: The Case of Students in United Arab Emirates

    ERIC Educational Resources Information Center

    Harb, Nasri; El-Shaarawi, Ahmed

    2007-01-01

    In this study, the authors found that the most important factor that affected student performance was their competence in speaking English. The sample was a group of 864 business and economics students in United Arab Emirates. The authors used regression analysis for the study. The results of the study showed that students who participated in…

  8. Students Perceptions on Factors That Affect Their Academic Performance: The Case of Great Zimbabwe University (GZU)

    ERIC Educational Resources Information Center

    Mapuranga, Barbra; Musingafi, Maxwell C. C.; Zebron, Shupikai

    2015-01-01

    Some educators argue that entry standards are the most important determinants of successful completion of a university programme; others maintain that non-academic factors must also be considered. In this study we sought to investigate open and distance learning students' perceptions of the factors affecting academic performance and successful…

  9. Study of Core Competency Elements and Factors Affecting Performance Efficiency of Government Teachers in Northeastern Thailand

    ERIC Educational Resources Information Center

    Chansirisira, Pacharawit

    2012-01-01

    The research aimed to investigate the core competency elements and the factors affecting the performance efficiency of the civil service teachers in the northeastern region, Thailand. The research procedure consisted of two steps. In the first step, the data were collected using a questionnaire with the reliability (Cronbach's Alpha) of 0.90. The…

  10. Factors Affecting University Entrants' Performance in High-Stakes Tests: A Multiple Regression Analysis

    ERIC Educational Resources Information Center

    Uy, Chin; Manalo, Ronaldo A.; Cabauatan, Ronaldo R.

    2015-01-01

    In the Philippines, students seeking admission to a university are usually required to meet certain entrance requirements, including passing the entrance examinations with questions on IQ and English, mathematics, and science. This paper aims to determine the factors that affect the performance of entrants into business programmes in high-stakes…

  11. Antecedent Factors Affecting Academic Performance of Graduate Students at the Nairobi Evangelical Graduate School of Theology

    ERIC Educational Resources Information Center

    Mbogo, Rosemary Wahu

    2016-01-01

    This paper reports the findings of a Master's level thesis work that was done in 1997 to assess the antecedent factors affecting the academic performance of graduate students at the Nairobi Evangelical School of Theology (N.E.G.S.T.), which is currently Africa International University (AIU). The paper reviews the effect of lack of finance on…

  12. Performance evaluation of hybrid VLC using device cost and power over data throughput criteria

    NASA Astrophysics Data System (ADS)

    Lee, C. C.; Tan, C. S.; Wong, H. Y.; Yahya, M. B.

    2013-09-01

    Visible light communication (VLC) technology has attained its attention in both academic and industry lately. It is determined by the development of light emitting diode (LED) technology for solid-state lighting (SSL).It has great potential to gradually replace radio frequency (RF) wireless technology because it offers unregulated and unlicensed bandwidth to withstand future demand of indoor wireless access to real-time bandwidth-demanding applications. However, it was found to provide intrusive uplink channel that give rise to unpleasant irradiance from the user device which could interfere with the downlink channel of VLC and hence limit mobility to users as a result of small coverage (field of view of VLC).To address this potential problem, a Hybrid VLC system which integrates VLC (for downlink) and RF (for uplink) technology is proposed. It offers a non-intrusive RF back channel that provides high throughput VLC and maintains durability with conventional RF devices. To deploy Hybrid VLC system in the market, it must be energy and cost saving to attain its equivalent economical advantage by comparing to existing architecture that employs fluorescent or LED lights with RF technology. In this paper, performance evaluation on the proposed hybrid system was carried out in terms of device cost and power consumption against data throughput. Based on our simulation, Hybrid VLC system was found to reduce device cost by 3% and power consumption by 68% when compares to fluorescent lights with RF technology. Nevertheless, when it is compared to LED lights with RF technology, our proposed hybrid system is found to achieve device cost saving as high as 47% and reduced power consumption by 49%. Such promising results have demonstrated that Hybrid VLC system is a feasible solution and has paved the way for greater cost saving and energy efficient compares with the current RF architecture even with the increasing requirement of indoor area coverage.

  13. Stress-induced Effects Caused by 3D IC TSV Packaging in Advanced Semiconductor Device Performance

    SciTech Connect

    Sukharev, V.; Kteyan, A.; Choy, J.-H.; Hovsepyan, H.; Markosian, A.; Zschech, E.; Huebner, R.

    2011-11-10

    Potential challenges with managing mechanical stress and the consequent effects on device performance for advanced 3D through-silicon-via (TSV) based technologies are outlined. The paper addresses the growing need in a simulation-based design verification flow capable to analyze a design of 3D IC stacks and to determine across-die out-of-spec variations in device electrical characteristics caused by the layout and through-silicon-via (TSV)/package-induced mechanical stress. The limited characterization/measurement capabilities for 3D IC stacks and a strict ''good die'' requirement make this type of analysis critical for the achievement of an acceptable level of functional and parametric yield and reliability. The paper focuses on the development of a design-for-manufacturability (DFM) type of methodology for managing mechanical stresses during a sequence of designs of 3D TSV-based dies, stacks and packages. A set of physics-based compact models for a multi-scale simulation to assess the mechanical stress across the device layers in silicon chips stacked and packaged with the 3D TSV technology is proposed. A calibration technique based on fitting to measured stress components and electrical characteristics of the test-chip devices is presented. A strategy for generation of a simulation feeding data and respective materials characterization approach are proposed, with the goal to generate a database for multi-scale material parameters of wafer-level and package-level structures. For model validation, high-resolution strain measurements in Si channels of the test-chip devices are needed. At the nanoscale, the transmission electron microscopy (TEM) is the only technique available for sub-10 nm strain measurements so far.

  14. Defects in silicon effect on device performance and relationship to crystal growth conditions

    NASA Technical Reports Server (NTRS)

    Jastrzebski, L.

    1985-01-01

    A relationship between material defects in silicon and the performance of electronic devices will be described. A role which oxygen and carbon in silicon play during the defects generation process will be discussed. The electronic properties of silicon are a strong function of the oxygen state in the silicon. This state controls mechanical properties of silicon efficiency for internal gettering and formation of defects in the device's active area. In addition, to temperature, time, ambience, and the cooling/heating rates of high temperature treatments, the oxygen state is a function of the crystal growth process. The incorporation of carbon and oxygen into silicon crystal is controlled by geometry and rotation rates applied to crystal and crucible during crystal growths. Also, formation of nucleation centers for oxygen precipitation is influenced by the growth process, although there is still a controversy which parameters play a major role. All these factors will be reviewed with special emphasis on areas which are still ambiguous and controversial.

  15. Vertically Stacked Graphene/Transition-Metal-Dichalcogenides/Graphene Heterojunction Devices for High Performance Photodetectors

    NASA Astrophysics Data System (ADS)

    Heo, Jinseong; Jeong, Heejeong; Lee, Jaeho; Lee, Kiyoung; Lee, Eun-Kyu; Lee, Sangyeob; Cho, Yeonchoo; Byun, Kyung-Eun; Lee, Chang-Won; Park, Seongjun; Hwang, Sungwoo

    Photodetectors based on vertically stacked graphene heterojunctions have advantages of short transit length for photo-generated carriers and large sensing area, thus implying fast response time and high responsivity. Previously, vertically stacked Graphene (Gr)/Transition-Metal-Dichalcogenide (TMDC)/Gr junctions were introduced for optoelectronic devices, showing high current on and off ratio as well as photoresponsivity. But for high performance photodetectors, both thorough and comparative study in terms of the figures of merit such as photoresponse time and photoresponsivity depending on different TMDC materials is crucial. Here, we report fast response time (28 us) and high responsivity (20 A/W) from Gr/WSe2 and MoS2/Gr, respectively. At the same time, those devices operate as p- and n-type barrier-variable transistors, respectively, being a potential building block for optoelectronic system on a chip.

  16. A new high performance field reversed configuration operating regime in the C-2 device

    SciTech Connect

    Tuszewski, M.; Smirnov, A.; Thompson, M. C.; Barnes, D.; Binderbauer, M. W.; Brown, R.; Bui, D. Q.; Clary, R.; Conroy, K. D.; Deng, B. H.; Dettrick, S. A.; Douglass, J. D.; Garate, E.; Glass, F. J.; Gota, H.; Guo, H.Y.; Gupta, D.; Gupta, S.; Kinley, J. S.; Knapp, K.; and others

    2012-05-15

    Large field reversed configurations (FRCs) are produced in the C-2 device by combining dynamic formation and merging processes. The good confinement of these FRCs must be further improved to achieve sustainment with neutral beam (NB) injection and pellet fuelling. A plasma gun is installed at one end of the C-2 device to attempt electric field control of the FRC edge layer. The gun inward radial electric field counters the usual FRC spin-up and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. Better plasma centering is also obtained, presumably from line-tying to the gun electrodes. The combined effects of the plasma gun and of neutral beam injection lead to the high performance FRC operating regime, with FRC lifetimes up to 3 ms and with FRC confinement times improved by factors 2 to 4.

  17. Performance Enhancement of PFET Planar Devices by Plasma Immersion Ion Implantation (P3I)

    SciTech Connect

    Ortolland, Claude; Horiguchi, Naoto; Kerner, Christoph; Chiarella, Thomas; Eyben, Pierre; Everaert, Jean-Luc; Hoffmann, Thomas; Del Agua Borniquel, Jose Ignacio; Poon, Tze; Santhanam, Kartik; Porshnev, Peter; Foad, Majeed; Schreutelkamp, Robert; Absil, Philippe; Vandervorst, Wilfried; Felch, Susan

    2008-11-03

    A study of doping the pMOS Lightly Doped Drain (LDD) by Plasma Immersion Ion Implantation (P3i) with BF3 is presented which demonstrates a better transistor performance compared to standard beam line Ion Implantation (I/I). The benefit of P3i comes from the broad angular distribution of the impinging ions thereby doping the poly-silicon gate sidewall as well. Gate capacitance of short channel devices has been measured and clearly shows this improvement. This model is clearly supported by high resolution 2D-carrier profiles using Scanning Spreading Resistance Microscopy (SSRM) which shows this gate sidewall doping. The broad angular distribution also implies a smaller directional sensitivity (to for instance the detailed gate edge shape) and leads to devices which are perfectly balanced, when Source and Drain electrode are switched.

  18. The aerodynamic performance of several flow control devices for internal flow systems

    NASA Technical Reports Server (NTRS)

    Eckert, W. T.; Wettlaufer, B. M.; Mort, K. W.

    1982-01-01

    An experimental reseach and development program was undertaken to develop and document new flow-control devices for use in the major modifications to the 40 by 80 Foot wind tunnel at Ames Research Center. These devices, which are applicable to other facilities as well, included grid-type and quasi-two-dimensional flow straighteners, louver panels for valving, and turning-vane cascades with net turning angles from 0 deg to 90 deg. The tests were conducted at model scale over a Reynolds number range from 2 x 100,000 to 17 x 100,000, based on chord. The results showed quantitatively the performance benefits of faired, low-blockage, smooth-surface straightener systems, and the advantages of curved turning-vanes with hinge-line gaps sealed and a preferred chord-to-gap ratio between 2.5 and 3.0 for 45 deg or 90 deg turns.

  19. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    PubMed Central

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  20. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices.

    PubMed

    Polat, Emre O; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-01-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm(2) flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them. PMID:26578425

  1. Synthesis of Large Area Graphene for High Performance in Flexible Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Polat, Emre O.; Balci, Osman; Kakenov, Nurbek; Uzlu, Hasan Burkay; Kocabas, Coskun; Dahiya, Ravinder

    2015-11-01

    This work demonstrates an attractive low-cost route to obtain large area and high-quality graphene films by using the ultra-smooth copper foils which are typically used as the negative electrodes in lithium-ion batteries. We first compared the electronic transport properties of our new graphene film with the one synthesized by using commonly used standard copper foils in chemical vapor deposition (CVD). We observed a stark improvement in the electrical performance of the transistors realized on our graphene films. To study the optical properties on large area, we transferred CVD based graphene to transparent flexible substrates using hot lamination method and performed large area optical scanning. We demonstrate the promise of our high quality graphene films for large areas with ~400 cm2 flexible optical modulators. We obtained a profound light modulation over a broad spectrum by using the fabricated large area transparent graphene supercapacitors and we compared the performance of our devices with the one based on graphene from standard copper. We propose that the copper foils used in the lithium-ion batteries could be used to obtain high-quality graphene at much lower-cost, with the improved performance of electrical transport and optical properties in the devices made from them.

  2. Performance of electronic portal imaging devices (EPIDs) used in radiotherapy: image quality and dose measurements.

    PubMed

    Cremers, F; Frenzel, Th; Kausch, C; Albers, D; Schönborn, T; Schmidt, R

    2004-05-01

    The aim of our study was to compare the image and dosimetric quality of two different imaging systems. The first one is a fluoroscopic electronic portal imaging device (first generation), while the second is based on an amorphous silicon flat-panel array (second generation). The parameters describing image quality include spatial resolution [modulation transfer function (MTF)], noise [noise power spectrum (NPS)], and signal-to-noise transfer [detective quantum efficiency (DQE)]. The dosimetric measurements were compared with ionization chamber as well as with film measurements. The response of the flat-panel imager and the fluoroscopic-optical device was determined performing a two-step Monte Carlo simulation. All measurements were performed in a 6 MV linear accelerator photon beam. The resolution (MTF) of the fluoroscopic device (f 1/2 = 0.3 mm(-1)) is larger than of the amorphous silicon based system (f 1/2 = 0.21 mm(-1)), which is due to the missing backscattered photons and the smaller pixel size. The noise measurements (NPS) show the correlation of neighboring pixels of the amorphous silicon electronic portal imaging device, whereas the NPS of the fluoroscopic system is frequency independent. At zero spatial frequency the DQE of the flat-panel imager has a value of 0.008 (0.8%). Due to the minor frequency dependency this device may be almost x-ray quantum limited. Monte Carlo simulations verified these characteristics. For the fluoroscopic imaging system the DQE at low frequencies is about 0.0008 (0.08%) and degrades with higher frequencies. Dose measurements with the flat-panel imager revealed that images can only be directly converted to portal dose images, if scatter can be neglected. Thus objects distant to the detector (e.g., inhomogeneous dose distribution generated by a modificator) can be verified dosimetrically, while objects close to a detector (e.g., a patient) cannot be verified directly and must be scatter corrected prior to verification. This is

  3. Mathematics performance and the role played by affective and background factors peter grootenboer and brian hemmings

    NASA Astrophysics Data System (ADS)

    Grootenboer, Peter; Hemmings, Brian

    2007-12-01

    In this article, we report on a study examining those factors which contribute to the mathematics performance of a sample of children aged between 8 and 13 years. The study was designed specifically to consider the potency of a number of mathematical affective factors, as well as background characteristics (viz., gender, ethnicity, and socioeconomic status), on children's mathematics performance. Data were collected by surveying the children and drawing on performance ratings from their teachers. A correlation analysis revealed that the relationships between the respective dispositional and background variables with mathematics performance were significant and in the direction as predicted. Moreover, the findings from a logistic regression showed that a combination of these variables was able to appropriately classify students who either were below-average or above-average mathematics performers. We pay particular attention to the influence of certain dispositions with respect to mathematics performance and conclude by detailing the implications of the study for teachers and researchers.

  4. Universal and culture-specific factors in the recognition and performance of musical affect expressions.

    PubMed

    Laukka, Petri; Eerola, Tuomas; Thingujam, Nutankumar S; Yamasaki, Teruo; Beller, Grégory

    2013-06-01

    We present a cross-cultural study on the performance and perception of affective expression in music. Professional bowed-string musicians from different musical traditions (Swedish folk music, Hindustani classical music, Japanese traditional music, and Western classical music) were instructed to perform short pieces of music to convey 11 emotions and related states to listeners. All musical stimuli were judged by Swedish, Indian, and Japanese participants in a balanced design, and a variety of acoustic and musical cues were extracted. Results first showed that the musicians' expressive intentions could be recognized with accuracy above chance both within and across musical cultures, but communication was, in general, more accurate for culturally familiar versus unfamiliar music, and for basic emotions versus nonbasic affective states. We further used a lens-model approach to describe the relations between the strategies that musicians use to convey various expressions and listeners' perceptions of the affective content of the music. Many acoustic and musical cues were similarly correlated with both the musicians' expressive intentions and the listeners' affective judgments across musical cultures, but the match between musicians' and listeners' uses of cues was better in within-cultural versus cross-cultural conditions. We conclude that affective expression in music may depend on a combination of universal and culture-specific factors. PMID:23398579

  5. Neuropsychological performance and affective temperaments in Euthymic patients with bipolar disorder type II.

    PubMed

    Romero, Ester; Holtzman, Jessica N; Tannenhaus, Lucila; Monchablon, Romina; Rago, Carlo Mario; Lolich, Maria; Vázquez, Gustavo H

    2016-04-30

    Affective temperament has been suggested as a potential mediator of the effect between genetic predisposition and neurocognitive functioning. As such, this report seeks to assess the extent of the correlation between affective temperament and cognitive function in a group of bipolar II subjects. 46 bipolar II outpatients [mean age 41.4 years (SD 18.2); female 58.9%] and 46 healthy controls [mean age 35.1 years (SD 18); female 56.5%] were evaluated with regard to their demographic and clinical characteristics, affective temperament, and neurocognitive performance. Crude bivariate correlation analyses and multiple linear regression models were constructed between five affective temperament subscales and eight neurocognitive domains. Significant correlations were identified in bipolar patients between hyperthymic temperament and verbal memory and premorbid IQ; cyclothymic temperament and attention; and irritable temperament, attention, and verbal fluency. In adjusting for potential confounders of the relationship between temperament and cognitive function, the strongest mediating factors among the euthymic bipolar patients were found to be residual manic and depressive symptoms. It is therefore concluded that affective temperaments may partially influence the neurocognitive performance of both healthy controls and euthymic patients with bipolar disorder type II in several specific domains. PMID:27086230

  6. Improvement of device performance by using zinc oxide in hybrid organic-inorganic solar cells

    NASA Astrophysics Data System (ADS)

    Hayakawa, Akinobu; Sagawa, Takashi

    2016-02-01

    Zinc oxide (ZnO) nanopowder was applied to hybrid solar cells in combination with poly(3-hexylthiophene). Stability tests of the hybrid solar cell with or without encapsulation with glass and UV cut-off films were performed under 1 sun at 63 °C at a relative humidity of 50%. It was found that the sealed cell showed worse device performance in terms of the loss of the open-circuit voltage (Voc), whereas the unsealed cell exposed to air retained an almost constant Voc for more than 3 d under dark and atmospheric conditions. Placement in O2 atmosphere in the dark led to the recovery of Voc. Cation (Sn4+) doping into ZnO was performed, and the loss of Voc was effectively suppressed through the restraint of the supply of the excited electron from the valence band to the conduction band.

  7. A Quality Improvement Study on Avoidable Stressors and Countermeasures Affecting Surgical Motor Performance and Learning

    PubMed Central

    Conrad, Claudius; Konuk, Yusuf; Werner, Paul D.; Cao, Caroline G.; Warshaw, Andrew L.; Rattner, David W.; Stangenberg, Lars; Ott, Harald C.; Jones, Daniel B.; Miller, Diane L; Gee, Denise W.

    2012-01-01

    OBJECTIVE To explore how the two most important components of surgical performance - speed and accuracy - are influenced by different forms of stress and what the impact of music on these factors is. SUMMARY BACKGROUND DATA Based on a recently published pilot study on surgical experts, we designed an experiment examining the effects of auditory stress, mental stress, and music on surgical performance and learning, and then correlated the data psychometric measures to the role of music in a novice surgeon’s life. METHODS 31 surgeons were recruited for a crossover study. Surgeons were randomized to four simple standardized tasks to be performed on the Surgical SIM VR laparoscopic simulator, allowing exact tracking of speed and accuracy. Tasks were performed under a variety of conditions, including silence, dichotic music (auditory stress), defined classical music (auditory relaxation), and mental loading (mental arithmetic tasks). Tasks were performed twice to test for memory consolidation and to accommodate for baseline variability. Performance was correlated to the Brief Musical Experience Questionnaire (MEQ). RESULTS Mental loading influences performance with respect to accuracy, speed, and recall more negatively than does auditory stress. Defined classical music might lead to minimally worse performance initially, but leads to significantly improved memory consolidation. Furthermore, psychologic testing of the volunteers suggests that surgeons with greater musical commitment, measured by the MEQ, perform worse under the mental loading condition. CONCLUSION Mental distraction and auditory stress negatively affect specific components of surgical learning and performance. If used appropriately, classical music may positively affect surgical memory consolidation. It also may be possible to predict surgeons’ performance and learning under stress through psychological tests on the role of music in a surgeon’s life. Further investigation is necessary to determine

  8. The impact of target luminance and radiance on night vision device visual performance testing

    NASA Astrophysics Data System (ADS)

    Marasco, Peter L.; Task, H. Lee

    2003-09-01

    Visual performance through night-vision devices (NVDs) is a function of many parameters such as target contrast, objective and eyepiece lens focus, signal/noise of the image intensifier tube, quality of the image intensifier, night-vision goggle (NVG) gain, and NVG output luminance to the eye. The NVG output luminance depends on the NVG sensitive radiance emitted (or reflected) from the visual acuity target (usually a vision testing chart). The primary topic of this paper is the standardization (or lack thereof) of the radiance levels used for NVG visual acuity testing. The visual acuity chart light level might be determined in either photometric (luminance) units or radiometric (radiance) units. The light levels are often described as "starlight," "quarter moon," or "optimum" light levels and may not actually provide any quantitative photometric or radiometric information. While these terms may be useful to pilots and the users of night-vision devices, they are inadequate for accurate visual performance testing. This is because there is no widely accepted agreement in the night vision community as to the radiance or luminance level of the target that corresponds to the various named light levels. This paper examines the range of values for "starlight," "quarter moon," and "optimum" light commonly used by the night vision community and referenced in the literature. The impact on performance testing of variations in target luminance/radiance levels is also examined. Arguments for standardizing on NVG-weighted radiometric units for testing night-vision devices instead of photometric units are presented. In addition, the differences between theoretical weighted radiance and actual weighted radiance are also discussed.

  9. Influences of an Aluminum Covering Layer on the Performance of Cross-Like Hall Devices

    PubMed Central

    Lyu, Fei; Liu, Xinfu; Ding, Yinjie; Toh, Eng-Huat; Zhang, Zhenyan; Pan, Yifan; Wang, Zhen; Li, Chengjie; Li, Li; Sha, Jin; Pan, Hongbing

    2016-01-01

    This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were characterized using a self-built measurement system. The work analyzes the influences of the aluminum covering on those two aspects of the performance. The aluminum layer covering mainly leads to an eddy-current effect in an unstable magnetic field and an additional depletion region above the active region. Those two points have influences on the sensitivity and the offset voltage, respectively. The analysis guides the designer whether to choose covering with an aluminum layer the active region of the Hall sensor as a method to reduce the flicker noise and to improve the stability of the Hall sensor. Because Hall devices, as a reference element, always suffer from a large dispersion, improving their stability is a crucial issue. PMID:26784199

  10. Influences of an Aluminum Covering Layer on the Performance of Cross-Like Hall Devices.

    PubMed

    Lyu, Fei; Liu, Xinfu; Ding, Yinjie; Toh, Eng-Huat; Zhang, Zhenyan; Pan, Yifan; Wang, Zhen; Li, Chengjie; Li, Li; Sha, Jin; Pan, Hongbing

    2016-01-01

    This work studies the effects of an aluminum covering on the performance of cross-like Hall devices. Four different Hall sensor structures of various sizes were designed and fabricated. The sensitivity and offset of the Hall sensors, two key points impacting their performance, were characterized using a self-built measurement system. The work analyzes the influences of the aluminum covering on those two aspects of the performance. The aluminum layer covering mainly leads to an eddy-current effect in an unstable magnetic field and an additional depletion region above the active region. Those two points have influences on the sensitivity and the offset voltage, respectively. The analysis guides the designer whether to choose covering with an aluminum layer the active region of the Hall sensor as a method to reduce the flicker noise and to improve the stability of the Hall sensor. Because Hall devices, as a reference element, always suffer from a large dispersion, improving their stability is a crucial issue. PMID:26784199

  11. Performance of miniaturized direct methanol fuel cell (DMFC) devices using micropump for fuel delivery

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; Wang, Qing-Ming

    A fuel cell is a device that can convert chemical energy into electricity directly. Among various types of fuel cells, both polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) can work at low temperature (<80 °C). Therefore, they can be used to supply power for commercial portable electronics such as laptop computers, digital cameras, PDAs and cell phones. The focus of this paper is to investigate the performance of a miniaturized DMFC device using a micropump to deliver fuel. The core of this micropump is a piezoelectric ring-type bending actuator and the associated nozzle/diffuser for directing fuel flow. Based on the experimental measurements, it is found that the performance of the fuel cell can be significantly improved if enough fuel flow is induced by the micropump at anode. Three factors may contribute to the performance enhancement including replenishment of methanol, decrease of diffusion resistance and removal of carbon dioxide. In comparison with conventional mini pumps, the size of the piezoelectric micropump is much smaller and the energy consumption is much lower. Thus, it is very viable and effective to use a piezoelectric valveless micropump for fuel delivery in miniaturized DMFC power systems.

  12. How sleep deprivation affects psychological variables related to college students' cognitive performance.

    PubMed

    Pilcher, J J; Walters, A S

    1997-11-01

    The effects of sleep deprivation on cognitive performance psychological variables related to cognitive performance were studied in 44 college students. Participants completed the Watson-Glaser Critical Thinking Appraisal after either 24 hours of sleep deprivation or approximately 8 hours of sleep. After completing the cognitive task, the participants completed 2 questionnaires, one assessing self-reported effort, concentration, and estimated performance, the other assessing off-task cognitions. As expected, sleep-deprived participants performed significantly worse than the nondeprived participants on the cognitive task. However, the sleep-deprived participants rated their concentration and effort higher than the nondeprived participants did. In addition, the sleep-deprived participants rated their estimated performance significantly higher than the nondeprived participants did. The findings indicate that college students are not aware of the extent to which sleep deprivation negatively affects their ability to complete cognitive tasks. PMID:9394089

  13. Kilopixel X-Ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

    NASA Technical Reports Server (NTRS)

    Eckart, M. E.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Busch, S. E.; Chervenak, J. A.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Porst, J.-P.; Sadleir, J. E.; Smith, S. J.

    2012-01-01

    We are developing kilopixel arrays of TES microcalorimeters to enable high-resolution x-ray imaging spectrometers for future x-ray observatories and laboratory astrophysics experiments. Our current array design was targeted as a prototype for the X-ray Microcalorimeter Spectrometer proposed for the International X-ray Observatory, which calls for a 40×40-pixel core array of 300 micron devices with 2.5 eV energy resolution (at 6 keV). Here we present device characterization of our 32×32 arrays, including x-ray spectral performance of individual pixels within the array. We present our results in light of the understanding that our Mo/Au TESs act as weak superconducting links, causing the TES critical current (I(sub c)) and transition shape to oscillate with applied magnetic field (B). We show I(sub c)(B) measurements and discuss the uniformity of these measurements across the array, as well as implications regarding the uniformity of device noise and response. In addition, we are working to reduce pixel-to-pixel electrical and thermal crosstalk; we present recent test results from an array that has microstrip wiring and an angle-evaporated copper backside heatsinking layer, which provides copper coverage on the four sidewalls of the silicon wells beneath each pixel.

  14. Kilopixel X-Ray Microcalorimeter Arrays for Astrophysics: Device Performance and Uniformity

    NASA Technical Reports Server (NTRS)

    Eckart, M. E.; Adams, J. S.; Bailey, C. N.; Bandler, S. R.; Chervenak, F. M.

    2011-01-01

    We are developing kilo-pixel arrays of TES microcalorimeters to enable high-resolution X-ray imaging spectrometers for future X-ray observatories and laboratory astrophysics experiments. Our current array design was targeted as a prototype for the X-ray Microcalorimeter Spectrometer proposed for the International X-ray Observatory, which calls for a 40x40-pixel core array of 300 micron devices with 2.5 e V energy resolution (at 6 keV). Here we present device characterization of our 32x32 arrays, including X-ray spectral performance of individual pixels within the array. We present our results in light of the understanding that our Mo/Au TESs act as weak superconducting links, causing the TES critical current (Ic) and transition shape to oscillate with applied magnetic field (B). We show Ic(B) measurements and discuss the uniformity of these measurements across the array, as well as implications regarding the uniformity of device noise and response. In addition, we are working to reduce pixel-to-pixel electrical and thermal crosstalk; we present recent test results from an array that has microstrip wiring and an angle-evaporated Cu backside heatsinking layer, which provides Cu coverage on the four sidewalls of the silicon wells beneath each pixel.

  15. Characterization and device performance of (AgCu)(InGa)Se2 absorber layers

    SciTech Connect

    Hanket, Gregory; Boyle, Jonathan H.; Shafarman, William N.

    2009-06-08

    The study of (AgCu)(InGa)Se2 absorber layers is of interest in that Ag-chalcopyrites exhibit both wider bandgaps and lower melting points than their Cu counterparts. (AgCu)(InGa)Se2 absorber layers were deposited over the composition range 0 < Ag/(Ag+Cu) < 1 and 0.3 < Ga/(In+Ga) < 1.0 using a variety of elemental co-evaporation processes. Films were found to be singlephase over the entire composition range, in contrast to prior studies. Devices with Ga content 0.3 < Ga/(In+Ga) <0.5 tolerated Ag incorporation up to Ag/(Ag+Cu) = 0.5 without appreciable performance loss. Ag-containing films with Ga/(In+Ga) = 0.8 showed improved device characteristics over Cu-only control samples, in particular a 30-40% increase in short-circuit current. An absorber layer with composition Ag/(Ag+Cu) = 0.75 and Ga/(In+Ga) = 0.8 yielded a device with VOC = 890 mV, JSC = 20.5mA/cm2, fill factor = 71.3%, and η = 13.0%.

  16. [Effect of gas-lift device on the morphology and performance of ANAMMOX sludge].

    PubMed

    Li, Xiang; Huang, Yong; Yuan, Yi; Zhou, Cheng; Chen, Zong-Heng; Zhang, Da-Lin

    2014-12-01

    The upflow reactor with gas-lift device was started up by inoculating ANAMMOX sludge granules of less than 0.9 mm. The effects of gas lift device system on the morphology and performance of ANAMMOX sludge were studied by using the nitrogen gas produced in ANAMMOX to drive the effluent circulation in the reactor. The results showed that, the airlift circulation function was not clear in the startup stage of the reactor, because the nitrogen gas production was very low. At the same time, the ANAMMOX granular sludge was easy to condensate. When the load rate of nitrogen removal reached 3.4 kg x (m3 x d)(-1), the function of gas lift was significant, resulting in gradually increased effluent self-circulation, and the granules were dispersed and grew gradually. After 183d of operation, the granular sludge was dominated by the granules with sizes of 1.6-2.5 mm, which accounted for 53.2% of the total sludge volume. The MLVSS content increased with the increase of sludge particle size. The gas lift device had the same function as the external reflux pump, and was helpful for sludge granulation in the ANAMMOX reactor, while reducing power consumption and the cost of the equipment. PMID:25826935

  17. High Performance Field-Reversed Configuration Plasmas in the C-2 Device

    NASA Astrophysics Data System (ADS)

    Gota, H.; Tuszewski, M.; Smirnov, A.; Guo, H.; Binderbauer, M.; Barnes, D.; Akhmetov, T.; Ivanov, A.

    2012-10-01

    A high temperature, stable, long-lived field-reversed configuration (FRC) plasma state has been produced in the C-2 device by dynamically colliding and merging two oppositely directed compact toroids, by biasing edge plasma near the FRC separatrix from a plasma-gun (PG) located at one end of the C-2 device, and by neutral-beam (NB) injection. The PG creates an inward radial electric field (Er<0) which counters the usual FRC spin-up in the ion diamagnetic direction and mitigates the n = 2 rotational instability without applying quadrupole magnetic fields. Better plasma centering is also obtained, presumably from line-tying to the gun electrodes. The PG produces ExB velocity shear in the FRC edge layer which may explain observations of improved transport properties The FRCs are nearly axisymmetric, which enables fast ion confinement. The combined effects of the PG and of NB injection yield a new High Performance FRC (HPF) regime with confinement times improved by factors 2 to 4 and FRC lifetimes extended from 1 to 3 ms. A second PG was newly installed at the other end of the C-2 device, and new experimental campaigns with 2 PGs have been explored. Characteristics of the HPF regime will be presented at the meeting as well as newly obtained results with 2 PGs and NBs.

  18. Fluoropolymer coatings for improved carbon nanotube transistor device and circuit performance

    NASA Astrophysics Data System (ADS)

    Jang, Seonpil; Kim, Bongjun; Geier, Michael L.; Prabhumirashi, Pradyumna L.; Hersam, Mark C.; Dodabalapur, Ananth

    2014-09-01

    We report on the marked improvements in key device characteristics of single walled carbon nanotube (SWCNT) field-effect transistors (FETs) by coating the active semiconductor with a fluoropolymer layer such as poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE). The observed improvements include: (i) A reduction in off-current by about an order of magnitude, (ii) a significant reduction in the variation of threshold voltage, and (iii) a reduction in bias stress-related instability and hysteresis present in device characteristics. These favorable changes in device characteristics also enhance circuit performance and the oscillation amplitude, oscillation frequency, and increase the yield of printed complementary 5-stage ring oscillators. The origins of these improvements are explored by exposing SWCNT FETs to a number of vapor phase polar molecules which produce similar effects on the FET characteristics as the PVDF-TrFE. Coating of the active SWCNT semiconductor layer with a fluoropolymer will be advantageous for the adoption of SWCNT FETs in a variety of printed electronics applications.

  19. The insulation performance of reactive parylene films in implantable electronic devices

    PubMed Central

    Seymour, John P.; Elkasabi, Yaseen; Chen, Hsien-yeh; Lahann, Joerg; Kipke, Daryl R.

    2009-01-01

    Parylene-C (poly-chloro-p-xylylene) is an appropriate material for use in an implantable, microfabricated device. It is hydrophobic, conformally deposited, has a low dielectric constant, and superb biocompatibility. Yet for many bioelectrical applications, its poor wet adhesion may be an impassable shortcoming. This research contrasts parylene-C and poly(p-xylylene) functionalized with reactive group X (PPX-X) layers using long-term electrical soak and adhesion tests. The reactive parylene was made of complementary derivatives having aldehyde and aminomethyl side groups (PPX-CHO and PPX-CH2NH2 respectively). These functional groups have previously been shown to covalently react together after heating. Electrical testing was conducted in saline at 37°C on interdigitated electrodes with either parylene-C or reactive parylene as the metal layer interface. Results showed that reactive parylene devices maintained the highest impedance. Heat-treated PPX-X device impedance was 800% greater at 10 kHz and 70% greater at 1Hz relative to heated parylene-C controls after 60 days. Heat treatment proved to be critical for maintaining high impedance of both parylene-C and the reactive parylene. Adhesion measurements showed improved wet metal adhesion for PPX-X, which corresponds well with its excellent high frequency performance. PMID:19703712

  20. Gender Differences in Introductory University Physics Performance: The Influence of High School Physics Preparation and Affect

    NASA Astrophysics Data System (ADS)

    Hazari, Zahra

    2006-12-01

    The attrition of females studying physics after high school has been a continuing concern for the physics education community. If females are well prepared, feel confident, and do well in introductory college physics, they may be inclined to study physics further. This quantitative study uses HLM to identify factors from high school physics preparation (content, pedagogy, and assessment) and the affective domain that predict female and male performance in introductory college physics. The study includes controls for student demographic and academic background characteristics, and the final dataset consists of 1973 surveys from 54 introductory college physics classes. The results highlight high school physics and affective experiences that differentially predict female and male performance. These experiences include: learning requirements, computer graphing/analysis, long written problems, everyday world examples, community projects cumulative tests/quizzes, father's encouragement, family's belief that science leads to a better career, and the length of time students believe that high school physics would help in university physics. There were also experiences that similarly predict female and male performance. The results paint a dynamic picture of the factors from high school physics and the affective domain that influence the future physics performance of females and males. The implication is that there are many aspects to the teaching of physics in high school that, although widely used and thought to be effective, need reform in their implementation in order to be fully beneficial to females and/or males in college.

  1. Image quality degradation by light-scattering processes in high-performance display devices for medical imaging

    NASA Astrophysics Data System (ADS)

    Badano, Aldo

    1999-11-01

    This thesis addresses the characterization of light scattering processes that degrade image quality in high performance electronic display devices for digital radiography. Using novel experimental and computational tools, we study the lateral diffusion of light in emissive display devices that causes extensive veiling glare and significant reduction of the physical contrast. In addition, we examine the deleterious effects of ambient light reflections that affect the contrast of low luminance regions, and superimpose unwanted structured signal. The analysis begins by introducing the performance limitations of the human visual system to define high fidelity requirements. It is noted that current devices severely suffer from image quality degradation due to optical transport processes. To model the veiling glare and reflectance characteristics of display devices, we introduce a Monte Carlo light transport simulation code, DETECT-II, that tracks individual photons through multiple scattering events. The simulation accounts for the photon polarization state at each scattering event, and provides descriptions for rough surfaces and thin film coatings. A new experimental method to measure veiling glare is described next, based on a conic collimated probe that minimizes contamination from bright areas. The measured veiling glare ratio is taken to be the luminance in the surrounding bright field divided by the luminance in the dark circle. We show that veiling glare ratios in the order of a few hundreds can be measured with an uncertainty of a few percent. The veiling glare response function is obtained by measuring the small spot contrast ratio of test patterns having varying dark spot radius. Using DETECT-II, we then estimate the ring response functions for a high performance medical imaging monitor of current design, and compare the predictions of the model with the experimentally measured response function. The data presented in this thesis demonstrate that although

  2. Human resources management and firm performance: The differential role of managerial affective and continuance commitment.

    PubMed

    Gong, Yaping; Law, Kenneth S; Chang, Song; Xin, Katherine R

    2009-01-01

    In this study, the authors developed a dual-concern (i.e., maintenance and performance) model of human resources (HR) management. The authors identified commonly examined HR practices that apply to the middle manager level and classified them into the maintenance- and performance-oriented HR subsystems. The authors found support for the 2-factor model on the basis of responses from 2,148 managers from 463 firms operating in China. Regression results indicate that the performance-oriented HR subsystems had a positive relationship with firm performance and that the relationship was mediated by middle managers' affective commitment to the firm. The maintenance-oriented HR subsystems had a positive relationship with middle managers' continuance commitment but not with their affective commitment and firm performance. This study contributes to the understanding of how HR practices relate to firm performance and offers an improved test of the argument that valuable and firm-specific HR provide a source of competitive advantage. (PsycINFO Database Record (c) 2009 APA, all rights reserved). PMID:19186911

  3. Centrality and charisma: comparing how leader networks and attributions affect team performance.

    PubMed

    Balkundi, Prasad; Kilduff, Martin; Harrison, David A

    2011-11-01

    When leaders interact in teams with their subordinates, they build social capital that can have positive effects on team performance. Does this social capital affect team performance because subordinates come to see the leader as charismatic? We answered this question by examining 2 models. First, we tested the charisma-to-centrality model according to which the leader's charisma facilitates the occupation of a central position in the informal advice network. From this central position, the leader positively influences team performance. Second, we examined the centrality-to-charisma model according to which charisma is attributed to those leaders who are socially active in terms of giving and receiving advice. Attributed charisma facilitates increased team performance. We tested these 2 models in 2 different studies. In the first study, based on time-separated, multisource data emanating from members of 56 work teams, we found support for the centrality-to-charisma model. Formal leaders who were central within team advice networks were seen as charismatic by subordinates, and this charisma was associated with high team performance. To clarify how leader network centrality affected the emergence of charismatic leadership, we designed Study 2 in which, for 79 student teams, we measured leader networking activity and leader charisma at 2 different points in time and related these variables to team performance measured at a third point in time. On the basis of this temporally separated data set, we again found support for the centrality-to-charisma model. PMID:21895351

  4. The effect of high-resistance SnO2 on CdS/CdTe device performance

    NASA Astrophysics Data System (ADS)

    Li, X.; Ribelin, R.; Mahathongdy, Y.; Albin, D.; Dhere, R.; Rose, D.; Asher, S.; Moutinho, H.; Sheldon, P.

    1999-03-01

    In this paper, we have studied the effect of high-resistance SnO2 buffer layers, deposited by low-pressure chemical-vapor deposition, on CdS/CdTe device performance. Our results indicate that when CdS/CdTe devices have a very thin layer of CdS or no CdS at all, the i-SnO2 buffer layer helps to increase device efficiency. When the CdS layer is thicker than 600 Å, the device performance is dominated by CdS thickness, not the i-SnO2 layer. If a very thin CdS layer is to be used to enhance device performance, we conclude that a better SnO2 buffer layer is needed.

  5. The Effect of High-Resistance SnO2 on CdS/CdTe Device Performance

    SciTech Connect

    Li, W.; Ribelin, R.; Mahathongdy, Y.; Albin, D.; Dhere, R.; Rose, D.; Asher, S.; Moutinho, H.; Sheldon, P.

    1998-10-06

    In this paper, we have studied the effect of high-resistance SnO2 buffer layers, deposited by low-pressure chemical-vapor deposition, on CdS/CdTe device performance. Our results indicate that when CdS/CdTe devices have a very thin layer of CdS or no CdS at all, the i-SnO2 buffer layer helps to increase device efficiency. When the CdS layer is thicker than 600{angstrom}, the device performance is dominated by CdS thickness, not the i-SnO2 layer. If a very thin CdS layer is to be used to enhance device performance, we conclude that a better SnO2 buffer layer is needed.

  6. The effects of control order, feedback, practice, and input device on tracking performance and perceived workload

    NASA Technical Reports Server (NTRS)

    Hancock, P. A.; Robinson, M. A.

    1989-01-01

    The present experiment examined the influence of several task-related factors on tracking performance and concomitant workload. The manipulated factors included tracking order, the presence or absence of knowledge of performance, and the control device. Summed root mean square error (rmse) and perceived workload were measured at the termination of each trial. Perceived workload was measured using the NASA Task Load Index (TLX) and the Subjective Workload Assessment Technique (SWAT). Results indicated a large and expected effect for track order on both performance and the perception of load. In general, trackball input was more accurate and judged for lower load than input using a mouse. The presence or absence of knowledge of performance had little effect on either performance or workload. There were a number of interactions between factors shown in performance that were mirrored by perceived workload scores. Results from each workload scale were equivalent in terms of sensitivity to task manipulations. The pattern of results affirm the utility of these workload measures in assessing the imposed load of multiple task-related variables.

  7. Does the inclusion of protease inhibitors in the insemination extender affect rabbit reproductive performance?

    PubMed

    Casares-Crespo, L; Vicente, J S; Talaván, A M; Viudes-de-Castro, M P

    2016-03-15

    The bioavailability of buserelin acetate when added to the seminal dose appears to be determined by the activity of the existing aminopeptidases. Thus, the addition of aminopeptidase inhibitors to rabbit semen extenders could be a solution to decrease the hormone degradation. This study was conducted to evaluate the effect of the protease activity inhibition on rabbit semen quality parameters and reproductive performance after artificial insemination. Seminal quality was not affected by the incubation with protease inhibitors, being the values of motility, viability, and acrosome integrity not significantly different between the protease inhibitors and the control group. In addition, seminal plasma aminopeptidase activity was inhibited in a 55.1% by the protease inhibitors. On the other hand, regarding the effect of protease inhibitors on reproductive performance, our results showed that the presence of protease inhibitors affected the prolificacy rate (9.2 ± 0.26 and 9.3 ± 0.23 vs. 8.2 ± 0.22 total born per litter for negative control, positive control, and aminopeptidase inhibitors group, respectively; P < 0.05), having this group one kit less per delivery. We conclude that the addition of a wide variety of protease inhibitors in the rabbit semen extender negatively affects prolificacy rate. Therefore, the development of new extenders with specific aminopeptidase inhibitors would be one of the strategies to increase the bioavailability of GnRH analogues without affecting the litter size. PMID:26639641

  8. Using representations in geometry: a model of students' cognitive and affective performance

    NASA Astrophysics Data System (ADS)

    Panaoura, Areti

    2014-05-01

    Self-efficacy beliefs in mathematics, as a dimension of the affective domain, are related with students' performance on solving tasks and mainly on overcoming cognitive obstacles. The present study investigated the interrelations of cognitive performance on geometry and young students' self-efficacy beliefs about using representations for solving geometrical tasks. The emphasis was on confirming a theoretical model for the primary-school and secondary-school students and identifying the differences and similarities for the two ages. A quantitative study was developed and data were collected from 1086 students in Grades 5-8. Confirmatory factor analysis affirmed the existence of a coherent model of affective dimensions about the use of representations for understanding the geometrical concepts, which becomes more stable across the educational levels.

  9. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    NASA Astrophysics Data System (ADS)

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-05-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities.

  10. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    PubMed

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-01-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities. PMID:24811826

  11. Using Mobile Devices and the Adobe Connect Web Conferencing Tool in the Assessment of EFL Student Teacher Performance

    ERIC Educational Resources Information Center

    Bolona Lopez, Maria del Carmen; Ortiz, Margarita Elizabeth; Allen, Christopher

    2015-01-01

    This paper describes a project to use mobile devices and video conferencing technology in the assessment of student English as a Foreign Language (EFL) teacher performance on teaching practice in Ecuador. With the increasing availability of mobile devices with video recording facilities, it has become easier for trainers to capture teacher…

  12. Residue-free fabrication of high-performance graphene devices by patterned PMMA stencil mask

    SciTech Connect

    Shih, Fu-Yu; Chen, Shao-Yu; Wu, Tsuei-Shin; Wang, Wei-Hua; Liu, Cheng-Hua; Chen, Yang-Fang; Ho, Po-Hsun; Chen, Chun-Wei

    2014-06-15

    Two-dimensional (2D) atomic crystals and their hybrid structures have recently attracted much attention due to their potential applications. The fabrication of metallic contacts or nanostructures on 2D materials is very common and generally achieved by performing electron-beam (e-beam) lithography. However, e-beam lithography is not applicable in certain situations, e.g., cases in which the e-beam resist does not adhere to the substrates or the intrinsic properties of the 2D materials are greatly altered and degraded. Here, we present a residue-free approach for fabricating high-performance graphene devices by patterning a thin film of e-beam resist as a stencil mask. This technique can be generally applied to substrates with varying surface conditions, while causing negligible residues on graphene. The technique also preserves the design flexibility offered by e-beam lithography and therefore allows us to fabricate multi-probe metallic contacts. The graphene field-effect transistors fabricated by this method exhibit smooth surfaces, high mobility, and distinct magnetotransport properties, confirming the advantages and versatility of the presented residue-free technique for the fabrication of devices composed of 2D materials.

  13. Residue-free fabrication of high-performance graphene devices by patterned PMMA stencil mask

    NASA Astrophysics Data System (ADS)

    Shih, Fu-Yu; Chen, Shao-Yu; Liu, Cheng-Hua; Ho, Po-Hsun; Wu, Tsuei-Shin; Chen, Chun-Wei; Chen, Yang-Fang; Wang, Wei-Hua

    2014-06-01

    Two-dimensional (2D) atomic crystals and their hybrid structures have recently attracted much attention due to their potential applications. The fabrication of metallic contacts or nanostructures on 2D materials is very common and generally achieved by performing electron-beam (e-beam) lithography. However, e-beam lithography is not applicable in certain situations, e.g., cases in which the e-beam resist does not adhere to the substrates or the intrinsic properties of the 2D materials are greatly altered and degraded. Here, we present a residue-free approach for fabricating high-performance graphene devices by patterning a thin film of e-beam resist as a stencil mask. This technique can be generally applied to substrates with varying surface conditions, while causing negligible residues on graphene. The technique also preserves the design flexibility offered by e-beam lithography and therefore allows us to fabricate multi-probe metallic contacts. The graphene field-effect transistors fabricated by this method exhibit smooth surfaces, high mobility, and distinct magnetotransport properties, confirming the advantages and versatility of the presented residue-free technique for the fabrication of devices composed of 2D materials.

  14. Asymmetric band offsets in silicon heterojunction solar cells: Impact on device performance

    DOE PAGESBeta

    Seif, Johannes Peter; Menda, Deneb; Descoeudres, Antoine; Barraud, Loris; Özdemir, Orhan; Ballif, Christophe; De Wolf, Stefaan

    2016-08-01

    Here, amorphous/crystalline silicon interfaces feature considerably larger valence than conduction band offsets. In this article, we analyze the impact of such band offset asymmetry on the performance of silicon heterojunction solar cells. To this end, we use silicon suboxides as passivation layers -- inserted between substrate and (front or rear) contacts -- since such layers enable intentionally exacerbated band-offset asymmetry. Investigating all topologically possible passivation layer permutations and focussing on light and dark current-voltage characteristics, we confirm that to avoid fill factor losses, wider-bandgap silicon oxide films (of at least several nanometer thin) should be avoided in hole-collecting contacts. Asmore » a consequence, device implementation of such films as window layers -- without degraded carrier collection -- demands electron collection at the front and hole collection at the rear. Furthermore, at elevated operating temperatures, once possible carrier transport barriers are overcome by thermionic (field) emission, the device performance is mainly dictated by the passivation of its surfaces. In this context, compared to the standard amorphous silicon layers, the wide-bandgap oxide layers applied here passivate remarkably better at these temperatures, which may represent an additional benefit under practical operation conditions.« less

  15. The Effect of Device Layout Schemes on RF Performance of Multi-Finger MOSFETs

    NASA Astrophysics Data System (ADS)

    Oh, Yongho; Rieh, Jae-Sung

    In this work, the effect of device dimension variation and metal wiring scheme on the RF performance of MOSFETs based on 0.13-µm RFCMOS technology has been investigated. Two sets of experiments have been carried out. In the first experiment, two types of source metal wiring options, each with various gate poly pitches, have been investigated. The results showed that the extrinsic capacitances (Cegs, Cegd) and parasitic resistances tend to increase with increasing gate poly pitch. Both cutoff frequency (fT) and maximum oscillation frequency (fmax) showed substantial degradation for the larger gate poly pitches. Based on measurement, we propose a simplified model for extrinsic parasitic capacitance as a function of gate poly pitch with different source metal wiring schemes. For the second experiment, the impact of gate metal wiring scheme and the number of gate fingers Nf on the RF performance of MOSFET has been studied. Two different types of gate metal wiring schemes, one with poly layer and the other with M2 layer, are compared. The measurement showed that the capacitance is slightly increased, while gate resistance significantly reduced, with the M2 gate wiring. As a result, fT is slightly degraded but fmax is significantly improved, especially for larger Nf, with the M2 gate wiring. The results in this work provide useful information regarding device dimension and metal wiring scheme for various RF applications of RF CMOS technology.

  16. Device Performance of the Mott Insulator LaVO3 as a Photovoltaic Material

    NASA Astrophysics Data System (ADS)

    Wang, Lingfei; Li, Yongfeng; Bera, Ashok; Ma, Chun; Jin, Feng; Yuan, Kaidi; Yin, Wanjian; David, Adrian; Chen, Wei; Wu, Wenbin; Prellier, Wilfrid; Wei, Suhuai; Wu, Tom

    2015-06-01

    Searching for solar-absorbing materials containing earth-abundant elements with chemical stability is of critical importance for advancing photovoltaic technologies. Mott insulators have been theoretically proposed as potential photovoltaic materials. In this paper, we evaluate their performance in solar cells by exploring the photovoltaic properties of Mott insulator LaVO3 (LVO). LVO films show an indirect band gap of 1.08 eV as well as strong light absorption over a wide wavelength range in the solar spectrum. First-principles calculations on the band structure of LVO further reveal that the d -d transitions within the upper and lower Mott-Hubbard bands and p -d transitions between the O 2 p and V 3 d band contribute to the absorption in visible and ultraviolet ranges, respectively. Transport measurements indicate strong carrier trapping and the formation of polarons in LVO. To utilize the strong light absorption of LVO and to overcome its poor carrier transport, we incorporate it as a light absorber in solar cells in conjunction with carrier transporters and evaluate its device performance. Our complementary experimental and theoretical results on such prototypical solar cells made of Mott-Hubbard transition-metal oxides pave the road for developing light-absorbing materials and photovoltaic devices based on strongly correlated electrons.

  17. Asymmetric band offsets in silicon heterojunction solar cells: Impact on device performance

    NASA Astrophysics Data System (ADS)

    Seif, Johannes Peter; Menda, Deneb; Descoeudres, Antoine; Barraud, Loris; Özdemir, Orhan; Ballif, Christophe; De Wolf, Stefaan

    2016-08-01

    Amorphous/crystalline silicon interfaces feature considerably larger valence than conduction band offsets. In this article, we analyze the impact of such band offset asymmetry on the performance of silicon heterojunction solar cells. To this end, we use silicon suboxides as passivation layers—inserted between substrate and (front or rear) contacts—since such layers enable intentionally exacerbated band-offset asymmetry. Investigating all topologically possible passivation layer permutations and focussing on light and dark current-voltage characteristics, we confirm that to avoid fill factor losses, wider-bandgap silicon oxide films (of at least several nanometer thin) should be avoided in hole-collecting contacts. As a consequence, device implementation of such films as window layers—without degraded carrier collection—demands electron collection at the front and hole collection at the rear. Furthermore, at elevated operating temperatures, once possible carrier transport barriers are overcome by thermionic (field) emission, the device performance is mainly dictated by the passivation of its surfaces. In this context, compared to the standard amorphous silicon layers, the wide-bandgap oxide layers applied here passivate remarkably better at these temperatures, which may represent an additional benefit under practical operation conditions.

  18. Vacancy associates-rich ultrathin nanosheets for high performance and flexible nonvolatile memory device.

    PubMed

    Liang, Lin; Li, Kun; Xiao, Chong; Fan, Shaojuan; Liu, Jiao; Zhang, Wenshuai; Xu, Wenhui; Tong, Wei; Liao, Jiaying; Zhou, Yingying; Ye, Bangjiao; Xie, Yi

    2015-03-01

    On the road of innovation in modern information technology, resistive switching random access memory (RRAM) has been considered to be the best potential candidate to replace the conventional Si-based technologies. In fact, the key prerequisite of high storage density and low power consumption as well as flexibility for the tangible next generation of nonvolatile memories has stimulated extensive research into RRAM. Herein, we highlight an inorganic graphene analogue, ultrathin WO3·H2O nanosheets with only 2-3 nm thickness, as a promising material to construct a high performance and flexible RRAM device. The abundant vacancy associates in the ultrathin nanosheets, revealed by the positron annihilation spectra, act not only carrier reservoir to provide carriers but also capture center to trap the actived Cu(2+) for the formation of conductive filaments, which synergistically realize the resistive switching memory with low operating voltage (+1.0 V/-1.14 V) and large resistance ON/OFF ratio (>10(5)). This ultrathin-nanosheets-based RRAM device also shows long retention time (>10(5) s), good endurance (>5000 cycles), and excellent flexibility. The finding of the existence of distinct defects in ultrathin nanosheets undoubtedly leads to an atomic level deep understanding of the underlying nature of the resistive switching behavior, which may serve as a guide to improve the performances and promote the rapid development of RRAM. PMID:25668153

  19. User-friendly tools on handheld devices for observer performance study

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takuya; Hara, Takeshi; Shiraishi, Junji; Fukuoka, Daisuke; Abe, Hiroyuki; Matsusako, Masaki; Yamada, Akira; Zhou, Xiangrong; Fujita, Hiroshi

    2012-02-01

    ROC studies require complex procedures to select cases from many data samples, and to set confidence levels in each selected case to generate ROC curves. In some observer performance studies, researchers have to develop software with specific graphical user interface (GUI) to obtain confidence levels from readers. Because ROC studies could be designed for various clinical situations, it is difficult task for preparing software corresponding to every ROC studies. In this work, we have developed software for recording confidence levels during observer studies on tiny personal handheld devices such as iPhone, iPod touch, and iPad. To confirm the functions of our software, three radiologists performed observer studies to detect lung nodules by using public database of chest radiograms published by Japan Society of Radiological Technology. The output in text format conformed to the format for the famous ROC kit from the University of Chicago. Times required for the reading each case was recorded very precisely.

  20. An integrated high-performance ratio-metric wavelength measurement device on glass

    NASA Astrophysics Data System (ADS)

    Wang, Gencheng; Yang, Bing; Shen, Ao; Pei, Chongyang; Yang, Longzhi; Yu, Hui; Jiang, Xiaoqing; Li, Yubo; Hao, Yinlei; Yang, Jianyi

    2015-10-01

    The measurable wavelength range and the resolution of the ratio-metric wavelength monitor are limited by each other in a conventional structure. To solve this problem we designed and fabricated a high-performance integrated double ratio-metric wavelength measurement device on glass by the method of ion-exchange. It consists of four unbalanced Mach-Zehnder interferometers (MZIs) to form a rough wavelength measurement with a wide range and a fine wavelength measurement with high resolution. The highest measured resolution can reach 10 pm in a 1.6 nm-wide wavelength range for the fine wavelength measurement together with a 45 nm-wide wavelength range for the rough measurement. By heating the unbalanced MZI, the performance of the fine wavelength monitor can be improved.

  1. Bisphenol A does not affect memory performance in adult male rats.

    PubMed

    Kuwahara, Rika; Kawaguchi, Shinichiro; Kohara, Yumi; Jojima, Takeshi; Yamashita, Kimihiro

    2014-04-01

    Bisphenol A (BPA) is an estrogenic endocrine disruptor used for producing polycarbonate plastics and epoxy resins. This study investigated the effects of oral BPA administration on memory performance, general activity, and emotionality in adult male Sprague Dawley rats using a battery of behavioral tests, including an appetite-motivated maze test (MAZE test) used to assess spatial memory performance. In addition, in order to confirm the effects of BPA on spatial memory performance, we examined whether intrahippocampal injection of BPA affects spatial memory consolidation. In the MAZE test, although oral BPA administration at 10 mg/kg significantly altered the number of entries into the incorrect area compared to those of vehicle-treated rats, male rats given BPA through either oral administration or intrahippocampal injection failed to show significant differences in latencies to reach the reward. Also, oral BPA administration did not affect fear-motivated memory performance in the step-through passive avoidance test. Oral BPA administration at 0.05 mg/kg, the lowest dose used in this study, was correlated with a decrease in locomotor activity in the open-field test, whereas oral administration at 10 mg/kg, the highest dose used in this study, was correlated with a light anxiolytic effect in the elevated plus-maze test. The present study suggests that BPA in adulthood has little effect on spatial memory performance in male rats. PMID:24326521

  2. Tadpole swimming performance and activity affected by acute exposure to sublethal levels of carbaryl

    USGS Publications Warehouse

    Bridges, C.M.

    1997-01-01

    General activity and swimming performance (i.e., sprint speed and distance) of plains leopard frog tadpoles (Rana blairi) were examined after acute exposure to three sublethal concentrations of carbaryl (3.5, 5.0, and 7.2 mg/L). Both swimming performance and spontaneous swimming activity are important for carrying out life history functions (e.g., growth and development) and for escaping from predators. Measured tadpole activity diminished by nearly 90% at 3.5 mg/L carbaryl and completely ceased at 7.2 mg/L. Sprint speed and sprint distance also decreased significantly following exposure. Carbaryl affected both swimming performance and activity after just 24 h, suggesting that 24 h may be an adequate length of exposure to determine behavioral effects on tadpoles. Slight recovery of activity levels was noted at 24 and 48 h post-exposure; no recovery of swimming performance was observed. Reduction in activity and swimming performance may result in increased predation rates and, because activity is closely associated with feeding, may result in slowed growth leading to a failure to emerge before pond drying or an indirect reduction in adult fitness. Acute exposure to sublethal toxicants such as carbaryl may not only affect immediate survival of tadpoles but also impact critical life history functions and generate changes at the local population level.

  3. Individual differences in cognition, affect, and performance: Behavioral, neuroimaging, and molecular genetic approaches

    PubMed Central

    Parasuraman, Raja; Jiang, Yang

    2012-01-01

    We describe the use of behavioral, neuroimaging, and genetic methods to examine individual differences in cognition and affect, guided by three criteria: (1) relevance to human performance in work and everyday settings; (2) interactions between working memory, decision-making, and affective processing; and (3) examination of individual differences. The results of behavioral, functional MRI (fMRI), event-related potential (ERP), and molecular genetic studies show that analyses at the group level often mask important findings associated with sub-groups of individuals. Dopaminergic/noradrenergic genes influencing prefrontal cortex activity contribute to inter-individual variation in working memory and decision behavior, including performance in complex simulations of military decision-making. The interactive influences of individual differences in anxiety, sensation seeking, and boredom susceptibility on evaluative decision-making can be systematically described using ERP and fMRI methods. We conclude that a multi-modal neuroergonomic approach to examining brain function (using both neuroimaging and molecular genetics) can be usefully applied to understanding individual differences in cognition and affect and has implications for human performance at work. PMID:21569853

  4. The Amicon Pro system--a centrifugal device capable of performing all steps in the protein purification workflow.

    PubMed

    Cappione, Amedeo; Mabuchi, Masaharu; Suhrawardy, Saosan; Briggs, David; Nadler, Timothy

    2013-01-01

    raditional protein purification is a long process with many steps utilizing multiple devices, often resulting in protein degradation and loss. The Amicon Pro device streamlines the affinity purification process by providing a single adaptable centrifugation unit capable of performing all steps in the affinity purification process. The device combines affinity-based spin column purification with downstream sample concentration and buffer exchange, eliminating the need for multiple sample transfers, thereby minimizing protein loss. The results presented in this work indicate that purification of His-tagged protein using the Amicon Pro device is faster, easier, and provides better yields than other traditional methods (eg. spin-column and slurry method). PMID:24364216

  5. Thought waves remotely affect the performance (output voltage) of photoelectric cells

    NASA Astrophysics Data System (ADS)

    Cao, Dayong; Cao, Daqing

    2012-02-01

    In our experiments, thought waves have been shown to be capable of changing (affecting) the output voltage of photovoltaic cells located from as far away as 1-3 meters. There are no wires between brain and photoelectric cell and so it is presumed only the thought waves act on the photoelectric cell. In continual rotations, the experiments tested different solar cells, measuring devices and lamps, and the experiments were done in different labs. The first experiment was conducted on Oct 2002. Tests are ongoing. Conclusions and assumptions include: 1) the slow thought wave has the energy of space-time as defined by C1.00007: The mass, energy, space and time systemic theory- MEST. Every process releases a field effect electrical vibration which be transmitted and focussed in particular paths; 2) the thought wave has the information of the order of tester; 3) the brain (with the physical system of MEST) and consciousness (with the spirit system of the mind, consciousness, emotion and desire-MECD) can produce the information (a part of them as the Genetic code); 4) through some algorithms such as ACO Ant Colony Optimization and EA Evolutionary Algorithm (or genetic algorithm) working in RAM, human can optimize the information. This Optimizational function is the intelligence; 5) In our experiments, not only can thought waves affect the voltage of the output photoelectric signals by its energy, but they can also selectively increase or decrease those photoelectric currents through remote consciousness interface and a conscious-brain information technology.

  6. Optimization of organic photovoltaic device performance via exciton generation profile adjustment

    NASA Astrophysics Data System (ADS)

    Quiroz-Sánchez, Juan Carlos; Cabrera-Arenas, Víctor; Villa-Angulo, Carlos

    2015-01-01

    We analyzed the conversion performance of conventional organic photovoltaic (OPV) and inverted organic photovoltaic (IOPV) devices with an active layer of polymer, PTB7: PC70BM. We computed the current density-voltage (JV) curves, short-circuit current density (Jsc), open-circuit voltage (Voc), maximum current density (Jmax), maximum power density (Pmax), and fill-factor (FF) under various scenarios. We employed the one-dimensional optical transfer matrix theory to calculate the light intensity that was then used as the input at the active layer for optical carrier generation. Then we obtained electrical performance parameters from the JV curves plotted by solving Poisson and charge transport equations. The effects of adjusting the exciton generation profile by tuning the active layer width and optical spacer thickness under 100 mW·cm-2 air mass 1.5 global (AM 1.5G) illumination are also analyzed. In addition, the effect on the conversion performance by using different electron and hole mobility relations in the polymers composing the active layer is computed. To identify the optimal performance, we proposed an exciton generation profile that maintains a constant amplitude when shifted through the active layer. Subsequently, by adjusting the active layer width, optical spacer thickness, and electron and hole mobility, we found that the OPV structure achieved performance characteristics previously reported only for IOPV structures.

  7. Improved Dynamic Modeling of the Cascade Distillation Subsystem and Analysis of Factors Affecting Its Performance

    NASA Technical Reports Server (NTRS)

    Perry, Bruce A.; Anderson, Molly S.

    2015-01-01

    The Cascade Distillation Subsystem (CDS) is a rotary multistage distiller being developed to serve as the primary processor for wastewater recovery during long-duration space missions. The CDS could be integrated with a system similar to the International Space Station Water Processor Assembly to form a complete water recovery system for future missions. A preliminary chemical process simulation was previously developed using Aspen Custom Modeler® (ACM), but it could not simulate thermal startup and lacked detailed analysis of several key internal processes, including heat transfer between stages. This paper describes modifications to the ACM simulation of the CDS that improve its capabilities and the accuracy of its predictions. Notably, the modified version can be used to model thermal startup and predicts the total energy consumption of the CDS. The simulation has been validated for both NaC1 solution and pretreated urine feeds and no longer requires retuning when operating parameters change. The simulation was also used to predict how internal processes and operating conditions of the CDS affect its performance. In particular, it is shown that the coefficient of performance of the thermoelectric heat pump used to provide heating and cooling for the CDS is the largest factor in determining CDS efficiency. Intrastage heat transfer affects CDS performance indirectly through effects on the coefficient of performance.

  8. Light conditions affect sexual performance in a lekking tephritid fruit fly.

    PubMed

    Díaz-Fleischer, Francisco; Arredondo, José

    2011-08-01

    Sensory systems are very susceptible to early environment experience. Mating success depends on the transmission of information from the signaller to the receiver, which means that sensory biases caused by developmental environment are likely to affect sexual selection. We investigated the impact of the developmental visual environment (light spectrum) on male copulation behaviour and female preference in the lekking tephritid Anastrepha ludens. We reared flies in four different light spectrum conditions - red light, blue light, shaded light and darkness - during their first 16 days after emerging from pupae. We found that the light environment experienced during early adulthood affected mating frequency and, in some cases, the latency to copulate, but not copulation duration. Males exposed to any of the three light treatments (red, blue or shaded light) were more frequently chosen as mating partners than dark-reared males. Flies reared under dark conditions exhibited the lowest mating performance out of any of the rearing environments. Under field cage conditions, a slight assortative mating between blue- and red-light-reared flies was detected. Additionally, females reared in blue light and darkness mated less compared with females reared in red and shaded light. Our data demonstrate that male mating behaviour is flexible in response to light environment. The findings suggest that light spectrum only weakly affects the direction of sexual selection by female choice; however, dark rearing environments deeply affect mating success. PMID:21753054

  9. Development of Cutting and Suction Device with Twist Blade Screw for Minimally Invasive Surgery: Evaluation of Suction Performance.

    PubMed

    Fujii, Yusuke; Suzuki, Takashi; Tamura, Manabu; Muragaki, Yoshihiro; Iseki, Hiroshi

    2015-01-01

    In this study, we aim to develop a narrow-diameter and long-bore device for minimally invasive surgery that achieves the simultaneous cutting and suction of body tissue such as the diseased part of an organ. In this paper, we propose a screw made of a thin metal plate, and we developed a prototype device using this screw. For smooth operation, the suction performance must be superior to the cutting performance. Therefore, we performed experiments and evaluated the suction performance of the developed device assuming the crushed tissue pieces correspond to a highly viscous fluid. From the results, we confirmed that the suction volume is almost proportional to the rotation speed of the screw in the low speed range, and the device has an upper limit of suction volume at a certain rotation speed. Considering practical use, its proportional speed range is suitable for the device controllability of cutting and suction volume, and the size of the device tip needs to be 1 mm or more. Based on these conditions, we are planning to examine the shape of the cutting edge for realizing efficient cutting and suction and we will complete the device. PMID:26132592

  10. Development of Cutting and Suction Device with Twist Blade Screw for Minimally Invasive Surgery: Evaluation of Suction Performance

    PubMed Central

    Fujii, Yusuke; Suzuki, Takashi; Tamura, Manabu; Muragaki, Yoshihiro; Iseki, Hiroshi

    2015-01-01

    In this study, we aim to develop a narrow-diameter and long-bore device for minimally invasive surgery that achieves the simultaneous cutting and suction of body tissue such as the diseased part of an organ. In this paper, we propose a screw made of a thin metal plate, and we developed a prototype device using this screw. For smooth operation, the suction performance must be superior to the cutting performance. Therefore, we performed experiments and evaluated the suction performance of the developed device assuming the crushed tissue pieces correspond to a highly viscous fluid. From the results, we confirmed that the suction volume is almost proportional to the rotation speed of the screw in the low speed range, and the device has an upper limit of suction volume at a certain rotation speed. Considering practical use, its proportional speed range is suitable for the device controllability of cutting and suction volume, and the size of the device tip needs to be 1 mm or more. Based on these conditions, we are planning to examine the shape of the cutting edge for realizing efficient cutting and suction and we will complete the device. PMID:26132592

  11. How Explicit and Implicit Test Instructions in an Implicit Learning Task Affect Performance

    PubMed Central

    Witt, Arnaud; Puspitawati, Ira; Vinter, Annie

    2013-01-01

    Typically developing children aged 5 to 8 years were exposed to artificial grammar learning. Following an implicit exposure phase, half of the participants received neutral instructions at test while the other half received instructions making a direct, explicit reference to the training phase. We first aimed to assess whether implicit learning operated in the two test conditions. We then evaluated the differential impact of age on learning performances as a function of test instructions. The results showed that performance did not vary as a function of age in the implicit instructions condition, while age effects emerged when explicit instructions were employed at test. However, performance was affected differently by age and the instructions given at test, depending on whether the implicit learning of short or long units was assessed. These results suggest that the claim that the implicit learning process is independent of age needs to be revised. PMID:23326409

  12. Design Procedure and Fabrication of Reproducible Silicon Vernier Devices for High-Performance Refractive Index Sensing

    PubMed Central

    Troia, Benedetto; Khokhar, Ali Z.; Nedeljkovic, Milos; Reynolds, Scott A.; Hu, Youfang; Mashanovich, Goran Z.; Passaro, Vittorio M. N.

    2015-01-01

    In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating in the second regime of the Vernier effect, around 1.55 μm. The experimental implementation of our design strategies has allowed a rigorous and reliable investigation of the influence of racetrack resonator and directional coupler dimensions as well as of waveguide process variability on the operation of Vernier devices. Figures of merit of our Vernier architectures have been measured experimentally, evidencing a high reproducibility and a very good agreement with the theoretical predictions, as also confirmed by relative errors even lower than 1%. Finally, a Vernier gain as high as 30.3, average insertion loss of 2.1 dB and extinction ratio up to 30 dB have been achieved. PMID:26067193

  13. High performance electronic device for the measurement of the inverse spin Hall effect

    NASA Astrophysics Data System (ADS)

    Gómez, Javier E.; Guillén, Matías; Butera, Alejandro; Albaugh, Neil P.

    2016-02-01

    We have developed a high performance analog electronic device that can be used for the measurement of the inverse spin Hall effect (ISHE) as a function of the applied magnetic field. The electronic circuit is based on the synchronous detection technique with a careful selection of the active components in order to optimize the response in this application. The electronic accessory was adapted for the simultaneous measurement of the ISHE signal and the microwave absorption in an electron spin resonance spectrometer and tested with a bilayer sample of 5 nm of permalloy (Ni80Fe20) and 5 nm of tantalum. The response of the electronic device was characterized as a function of the microwave power, the amplitude and frequency of the modulation signal, and the relative phase between signal and reference. This last characterization reveals a simple method to put in phase the signal with the reference. The maximum signal to noise ratio was achieved for a modulation frequency between 6 and 12 kHz, for the largest possible values of field modulation amplitude and microwave power.

  14. High performance electronic device for the measurement of the inverse spin Hall effect.

    PubMed

    Gómez, Javier E; Guillén, Matías; Butera, Alejandro; Albaugh, Neil P

    2016-02-01

    We have developed a high performance analog electronic device that can be used for the measurement of the inverse spin Hall effect (ISHE) as a function of the applied magnetic field. The electronic circuit is based on the synchronous detection technique with a careful selection of the active components in order to optimize the response in this application. The electronic accessory was adapted for the simultaneous measurement of the ISHE signal and the microwave absorption in an electron spin resonance spectrometer and tested with a bilayer sample of 5 nm of permalloy (Ni80Fe20) and 5 nm of tantalum. The response of the electronic device was characterized as a function of the microwave power, the amplitude and frequency of the modulation signal, and the relative phase between signal and reference. This last characterization reveals a simple method to put in phase the signal with the reference. The maximum signal to noise ratio was achieved for a modulation frequency between 6 and 12 kHz, for the largest possible values of field modulation amplitude and microwave power. PMID:26931877

  15. Performance prediction of four-contact vertical Hall-devices using a conformal mapping technique

    NASA Astrophysics Data System (ADS)

    Yang, Huang; Yue, Xu; Yufeng, Guo

    2015-12-01

    Instead of the conventional design with five contacts in the sensor active area, innovative vertical Hall devices (VHDs) with four contacts and six contacts are asymmetrical in structural design but symmetrical in the current flow that can be well fit for the spinning current technique for offset elimination. In this article, a conformal mapping calculation method is used to predict the performance of asymmetrical VHD embedded in a deep n-well with four contacts. Furthermore, to make the calculation more accurate, the junction field effect is also involved into the conformal mapping method. The error between calculated and simulated results is less than 5% for the current-related sensitivity, and approximately 13% for the voltage-related sensitivity. This proves that such calculations can be used to predict the optimal structure of the vertical Hall-devices. Project supported by the Natural Science Foundation of Jiangsu Province, China (Nos. BK20131379, BK20141431) and the Graduate Research and Innovation Projects of Jiangsu Province (No. SJLX_0373).

  16. A new device for performing reference point indentation without a reference probe

    NASA Astrophysics Data System (ADS)

    Bridges, Daniel; Randall, Connor; Hansma, Paul K.

    2012-04-01

    Here we describe a novel, hand-held reference point indentation (RPI), instrument that is designed for clinical measurements of bone material properties in living patients. This instrument differs from previous RPI instruments in that it requires neither a reference probe nor removal of the periosteum that covers the bone, thus significantly simplifying its use in patient testing. After describing the instrument, we discuss five guidelines for optimal and reproducible results. These are: (1) the angle between the normal to the surface and the axis of the instrument should be less than 10°, (2) the compression of the main spring to trigger the device must be performed slowly (>1 s), (3) the probe tip should be sharper than 10 μm; however, a normalized parameter with a calibration phantom can correct for dull tips up to a 100 μm radius, (4) the ambient room temperature should be between 4 °C and 37 °C, and (5) the effective mass of the bone or material under test must exceed 1 kg, or if under 1 kg, the specimen should be securely anchored in a fixation device with sufficient mass (which is not a requirement of previous RPI instruments). Our experience is that a person can be trained with these guidelines in about 5 min and thereafter obtain accurate and reproducible results. The portability, ease of use, and minimal training make this instrument suitable to measure bone material properties in a clinical setting.

  17. Design Procedure and Fabrication of Reproducible Silicon Vernier Devices for High-Performance Refractive Index Sensing.

    PubMed

    Troia, Benedetto; Khokhar, Ali Z; Nedeljkovic, Milos; Reynolds, Scott A; Hu, Youfang; Mashanovich, Goran Z; Passaro, Vittorio M N

    2015-01-01

    In this paper, we propose a generalized procedure for the design of integrated Vernier devices for high performance chemical and biochemical sensing. In particular, we demonstrate the accurate control of the most critical design and fabrication parameters of silicon-on-insulator cascade-coupled racetrack resonators operating in the second regime of the Vernier effect, around 1.55 μm. The experimental implementation of our design strategies has allowed a rigorous and reliable investigation of the influence of racetrack resonator and directional coupler dimensions as well as of waveguide process variability on the operation of Vernier devices. Figures of merit of our Vernier architectures have been measured experimentally, evidencing a high reproducibility and a very good agreement with the theoretical predictions, as also confirmed by relative errors even lower than 1%. Finally, a Vernier gain as high as 30.3, average insertion loss of 2.1 dB and extinction ratio up to 30 dB have been achieved. PMID:26067193

  18. Preliminary performance assessment of biotoxin detection for UWS applications using a MicroChemLab device.

    SciTech Connect

    VanderNoot, Victoria A.; Haroldsen, Brent L.; Renzi, Ronald F.; Shokair, Isaac R.

    2010-03-01

    In a multiyear research agreement with Tenix Investments Pty. Ltd., Sandia has been developing field deployable technologies for detection of biotoxins in water supply systems. The unattended water sensor or UWS employs microfluidic chip based gel electrophoresis for monitoring biological analytes in a small integrated sensor platform. This instrument collects, prepares, and analyzes water samples in an automated manner. Sample analysis is done using the {mu}ChemLab{trademark} analysis module. This report uses analysis results of two datasets collected using the UWS to estimate performance of the device. The first dataset is made up of samples containing ricin at varying concentrations and is used for assessing instrument response and detection probability. The second dataset is comprised of analyses of water samples collected at a water utility which are used to assess the false positive probability. The analyses of the two sets are used to estimate the Receiver Operating Characteristic or ROC curves for the device at one set of operational and detection algorithm parameters. For these parameters and based on a statistical estimate, the ricin probability of detection is about 0.9 at a concentration of 5 nM for a false positive probability of 1 x 10{sup -6}.

  19. Distractions, distractions: does instant messaging affect college students' performance on a concurrent reading comprehension task?

    PubMed

    Fox, Annie Beth; Rosen, Jonathan; Crawford, Mary

    2009-02-01

    Instant messaging (IM) has become one of the most popular forms of computer-mediated communication (CMC) and is especially prevalent on college campuses. Previous research suggests that IM users often multitask while conversing online. To date, no one has yet examined the cognitive effect of concurrent IM use. Participants in the present study (N = 69) completed a reading comprehension task uninterrupted or while concurrently holding an IM conversation. Participants who IMed while performing the reading task took significantly longer to complete the task, indicating that concurrent IM use negatively affects efficiency. Concurrent IM use did not affect reading comprehension scores. Additional analyses revealed that the more time participants reported spending on IM, the lower their reading comprehension scores. Finally, we found that the more time participants reported spending on IM, the lower their self-reported GPA. Implications and future directions are discussed. PMID:19006461

  20. Category fluency performance in patients with schizophrenia and bipolar disorder: The influence of affective categories.

    PubMed

    Rossell, Susan L

    2006-02-28

    Semantic fluency (SF) and phonological fluency (PF) were examined in large groups of schizophrenia patients, bipolar patients and controls. As well as standard SF categories (animals and food), fluency to two affective categories, happy and fear was measured, i.e. participants were asked to produce as many words as they could that resulted in or are associated with fear or happiness. Schizophrenia patients showed SF and PF deficits. Bipolar patients showed PF deficits. Thus, PF is argued to be a good cognitive marker in both disorders. Severity of delusions was related to SF performance in all patients. The patient groups showed different patterns on the affective categories compared to controls: the bipolar patients were better and produced more words, especially to the happiness category, and the schizophrenia patients were impaired and produced less words. The results suggest an interesting interaction between psychotic illnesses, fluency and emotion. PMID:16376054

  1. Gender differences in introductory university physics performance: The influence of high school physics preparation and affect

    NASA Astrophysics Data System (ADS)

    Hazari, Zahra Sana

    The attrition of females studying physics after high school is a concern to the science education community. Most undergraduate science programs require introductory physics coursework. Thus, success in introductory physics is necessary for students to progress to higher levels of science study. Success also influences attitudes; if females are well-prepared, feel confident, and do well in introductory physics, they may be inclined to study physics further. This quantitative study using multilevel modeling focused on determining factors from high school physics preparation (content, pedagogy, and assessment) and the affective domain that influenced female and male performance in introductory university physics. The study controlled for some university/course level characteristics as well as student demographic and academic background characteristics. The data consisted of 1973 surveys from 54 introductory physics courses within 35 universities across the US. The results highlight high school physics and affective experiences that differentially influenced female and male performance. These experiences include: learning requirements, computer graphing/analysis, long written problems, everyday world examples, community projects, cumulative tests/quizzes, father's encouragement, family's belief that science leads to a better career, and the length of time students believed that high school physics would help in university physics. There were also experiences that had a similar influence on female and male performance. Positively related to performance were: covering fewer topics for longer periods of time, the history of physics as a recurring topic, physics-related videos, and test/quiz questions that involved calculations and/or were drawn from standardized tests. Negatively related to performance were: student-designed projects, reading/discussing labs the day before performing them, microcomputer based laboratories, discussion after demonstrations, and family

  2. Study of parameters affecting the performance of solar desiccant cooling systems

    NASA Astrophysics Data System (ADS)

    Pesaran, A. A.; Hoo, E. A.

    1993-01-01

    The performance of a solar desiccant cooling system depends on the performance of its components, particularly the desiccant dehumidifier and solar collectors. The desiccant dehumidifier performance is affected by the properties of the desiccant, particularly the shape of the isotherm and the regeneration temperature. The performance of a solar collector, as one would expect, depends on its operating temperature, which is very close to the desiccant regeneration temperature. The purpose of this study was to identify the desiccant isotherm shape (characterized by separation factor) that would result in the optimum performance - based on thermal coefficient of performance and cooling capacity - of a desiccant cooling cycle operating in ventilation mode. Different regeneration temperatures ranging from 65 to 160 C were investigated to identify the corresponding optimum isotherm shape at each. Thermal COP dictates the required area of the solar collectors, and the cooling capacity is an indication of the size and cost of the cooling equipment. Staged and no-staged regeneration methods were studied.

  3. Experimental evaluation of cooling efficiency of the high performance cooling device

    NASA Astrophysics Data System (ADS)

    Nemec, Patrik; Malcho, Milan

    2016-06-01

    This work deal with experimental evaluation of cooling efficiency of cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description of cooling device, working principle of cooling device, construction of cooling device. Experimental part describe the measuring method of device cooling efficiency evaluation. The work results are presented in graphic visualization of temperature dependence of the contact area surface between cooling device evaporator and electronic components on the loaded heat of electronic components in range from 250 to 740 W and temperature dependence of the loop thermosiphon condenser surface on the loaded heat of electronic components in range from 250 to 740 W.

  4. Timing of examinations affects school performance differently in early and late chronotypes.

    PubMed

    van der Vinne, Vincent; Zerbini, Giulia; Siersema, Anne; Pieper, Amy; Merrow, Martha; Hut, Roelof A; Roenneberg, Till; Kantermann, Thomas

    2015-02-01

    Circadian clocks of adolescents typically run late-including sleep times-yet adolescents generally are expected at school early in the morning. Due to this mismatch between internal (circadian) and external (social) times, adolescents suffer from chronic sleep deficiency, which, in turn, affects academic performance negatively. This constellation affects students' future career prospects. Our study correlates chronotype and examination performance. In total, 4734 grades were collected from 741 Dutch high school students (ages 11-18 years) who had completed the Munich ChronoType Questionnaire to estimate their internal time. Overall, the lowest grades were obtained by students who were very late chronotypes (MSFsc > 5.31 h) or slept very short on schooldays (SDw < 7.03 h). The effect of chronotype on examination performance depended on the time of day that examinations were taken. Opposed to late types, early chronotypes obtained significantly higher grades during the early (0815-0945 h) and late (1000-1215 h) morning. This group difference in grades disappeared in the early afternoon (1245-1500 h). Late types also obtained lower grades than early types when tested at the same internal time (hours after MSFsc), which may reflect general attention and learning disadvantages of late chronotypes during the early morning. Our results support delaying high school starting times as well as scheduling examinations in the early afternoon to avoid discrimination of late chronotypes and to give all high school students equal academic opportunities. PMID:25537752

  5. Swimming performance of hatchling green turtles is affected by incubation temperature

    NASA Astrophysics Data System (ADS)

    Burgess, Elizabeth A.; Booth, David T.; Lanyon, Janet M.

    2006-08-01

    In an experiment repeated for two separate years, incubation temperature was found to affect the body size and swimming performance of hatchling green turtles ( Chelonia mydas). In the first year, hatchlings from eggs incubated at 26°C were larger in size than hatchlings from 28 and 30°C, whilst in the second year hatchlings from 25.5°C were similar in size to hatchings from 30°C. Clutch of origin influenced the size of hatchlings at all incubation temperatures even when differences in egg size were taken into account. In laboratory measurements of swimming performance, in seawater at 28°C, hatchlings from eggs incubated at 25.5 and 26°C had a lower stroke rate frequency and lower force output than hatchlings from 28 and 30°C. These differences appeared to be caused by the muscles of hatchlings from cooler temperatures fatiguing at a faster rate. Clutch of origin did not influence swimming performance. This finding that hatchling males incubated at lower temperature had reduced swimming ability may affect their survival whilst running the gauntlet of predators in shallow near-shore waters, prior to reaching the relative safety of the open sea.

  6. Effects of drought-affected corn and nonstarch polysaccharide enzyme inclusion on nursery pig growth performance.

    PubMed

    Jones, C K; Frantz, E L; Bingham, A C; Bergstrom, J R; DeRouchey, J M; Patience, J F

    2015-04-01

    The effectiveness of carbohydrase enzymes has been inconsistent in corn-based swine diets; however, the increased substrate of nonstarch polysaccharides in drought-affected corn may provide an economic model for enzyme inclusion, but this has not been evaluated. A total of 360 barrows (PIC 1050 × 337, initially 5.85 kg BW) were used to determine the effects of drought-affected corn inclusion with or without supplementation of commercial carbohydrases on growth performance and nutrient digestibility of nursery pigs. Initially, 34 corn samples were collected to find representatives of normal and drought-affected corn. The lot selected to represent the normal corn had a test weight of 719.4 kg/m3, 15.0% moisture, and 4.2% xylan. The lot selected to represent drought-affected corn had a test weight of 698.8 kg/m3, 14.3% moisture, and 4.7% xylan. After a 10-d acclimation period postweaning, nursery pigs were randomly allotted to 1 of 8 dietary treatments in a completely randomized design. Treatments were arranged in a 2 × 4 factorial with main effects of corn (normal vs. drought affected) and enzyme inclusion (none vs. 100 mg/kg Enzyme A vs. 250 mg/kg Enzyme B vs. 100 mg/kg Enzyme A + 250 mg/kg Enzyme B). Both enzymes were included blends of β-glucanase, cellulose, and xylanase (Enzyme A) or hemicellulase and pectinases (Enzyme B). Pigs were fed treatment diets from d 10 to 35 postweaning in 2 phases. Feed and fecal samples were collected on d 30 postweaning to determine apparent total tract digestibility of nutrients. The nutrient concentrations of normal and drought-affected corn were similar, which resulted in few treatment or main effects differences of corn type or enzyme inclusion. No interactions were observed (P > 0.10) between corn source and enzyme inclusion. Overall (d 10 to 35), treatments had no effect on ADG or ADFI, but enzyme A inclusion tended to improve (P < 0.10; 0.74 vs. 0.69) G:F, which was primarily driven by the improved feed efficiency (0

  7. Analytical ballistic theory of carbon nanotube transistors: Experimental validation, device physics, parameter extraction, and performance projection

    NASA Astrophysics Data System (ADS)

    Akinwande, Deji; Liang, Jiale; Chong, Soogine; Nishi, Yoshio; Wong, H.-S. Philip

    2008-12-01

    We developed a fully analytical ballistic theory of carbon nanotube field effect transistors enabled by the development of an analytical surface potential capturing the temperature dependence and gate and quantum capacitance electrostatics. The analytical ballistic theory is compared to the experimental results of a ballistic transistor with good agreement. The validated analytical theory enables intuitive circuit design, provides techniques for parameter extraction of the bandgap and surface potential, and elucidates on the device physics of drain optical phonon scattering and its role in reducing the linear conductance and intrinsic gain of the transistor. Furthermore, a threshold voltage definition is proposed reflecting the bandgap-diameter dependence. Projections for key analog and digital performances are discussed.

  8. Interfacial Chemistry and the Performance of Bromine-etched CdZnTe Radiation Detector Devices

    SciTech Connect

    Rouse, Ambrosio A.; Szeles, Csaba; Ndap, Jean-Oliver; Soldner, Steve; Parnham, K B.; Gaspar, Dan J.; Engelhard, Mark H.; Lea, Alan S.; Shutthanandan, V; Thevuthasan, Suntharampillai; Baer, Donald R.

    2002-08-01

    The interfacial chemistry and composition of Pt electrodes sputter deposited on bromine-etched CdZnTe surfaces was studied by XPS, SIMS, AES, NRA and RBS. The interfacial composition of a functioning and a non-functioning CdZnTe detector shows significant differences. The degree of cation out-diffusion into the Pt overlayer and the in-diffusion of Pt into the CdZnTe correlate with the degree of oxidation found at the metal-semiconductor interface. Practically all the oxide present at the interface was found to be TeO{sub 2}. The results suggest that the inter-diffusion of the atoms and associated charges contribute to stoichiometric variations at the metal-semiconductor interface and influence the electrical performance of the devices.

  9. Adaptive cellular structures and devices with internal features for enhanced structural performance

    NASA Astrophysics Data System (ADS)

    Pontecorvo, Michael Eugene

    This dissertation aims to develop a family of cellular and repeatable devices that exhibit a variety of force-displacement behaviors. It is envisioned that these cellular structures might be used either as stand-alone elements, or combined and repeated to create multiple types of structures (i.e. buildings, ship hulls, vehicle subfloors, etc.) with the ability to passively or actively perform multiple functions (harmonic energy dissipation, impact mitigation, modulus change) over a range of loading types, amplitudes, and frequencies. To accomplish this goal, this work combines repeatable structural frameworks, such as that provided by a hexagonal cellular structure, with internal structural elements such as springs, viscous dampers, buckling plates, bi-stable von Mises trusses (VMTs), and pneumatic artificial muscles (PAMs). The repeatable framework serves to position damping and load carrying elements throughout the structure, and the configuration of the internal elements allow each cell to be tuned to exhibit a desired force-displacement response. Therefore, gradient structures or structures with variable load paths can be created for an optimal global response to a range of loads. This dissertation focuses on the development of cellular structures for three functions: combined load-carrying capability with harmonic energy dissipation, impact mitigation, and cell modulus variation. One or more conceptual designs are presented for devices that can perform each of these functions, and both experimental measurements and simulations are used to gain a fundamental understanding of each device. Chapter 2 begins with a presentation of a VMT model that is the basis for many of the elements. The equations of motion for the VMT are derived and the static and dynamic behavior of the VMT are discussed in detail. Next, two metrics for the energy dissipation of the VMT - hysteresis loop area and loss factor - are presented. The responses of the VMT to harmonic displacement

  10. Hydraulic and hemodynamic performance of a minimally invasive intra-arterial right ventricular assist device.

    PubMed

    Hsu, Po-Lin; Graefe, Roland; Boehning, Fiete; Wu, Chen; Parker, Jack; Autschbach, Rüdiger; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2014-09-01

    Right ventricular assistance is still in the early phase of development compared to left ventricular assist device (LVAD) technology. In order to provide flexible pulmonary support and potentially reduce the known complications, we propose a minimally invasive right ventricular assist device (MIRVAD), located in the pulmonary artery (PA) and operating in series with the right ventricle (RV). The MIRVAD is an intra-arterial rotary blood pump containing a single axial impeller, which is not enclosed by a rigid housing but stent-fixed within the vessel. The impeller geometry has been designed with the assistance of analytical methods and computational fluid dynamics (CFD). The hydraulic performance of the impeller was evaluated experimentally with a customized test setup using blood synthetic medium (HES). The blade-tip clearance (BTC) was varied between 0.25-4.25 mm to evaluate the effect of different PA sizes on impeller performance. Furthermore, the Langrangian particle-tracking method was used to estimate the level of hemolysis and generate numerical blood damage indexes.The impeller design generated 25.6 mmHg for flow rates of 5 lpm at a speed of 6,000 rpm at the baseline condition, capable of providing sufficient support for the RV. The BTC presented a significant effect on the static pressure generation and the efficiency, but the operational range is suitable for most vessel sizes. The numerical results demonstrated a low risk of blood damage at the design point (mean Lagrangian damage index 2.6*10(-7)). The preliminary results have encouraged further impeller optimization and development of the MIRVAD. PMID:25262631

  11. Evaluation of left ventricular assist device performance and hydraulic force in a complete mock circulation loop.

    PubMed

    Timms, Daniel; Hayne, Mark; Tan, Andy; Pearcy, Mark

    2005-07-01

    Centrifugal pump performance characteristics are vital in determining the ability of a prototype left ventricular assist device (LVAD) to meet the physiological circulation requirements of the cardiovascular system. These characteristics influence the static hydraulic forces encountered by the pump impeller, which determine the required load stiffness of suspension type bearings to minimize impeller touchdown. Performance investigations were conducted on an LVAD design while characterizing the impeller static hydraulic forces of various impeller/volute configurations. The pumps were inserted into a complete systemic and pulmonary mock circulation rig configured to provide suitable nonpulsatile or simulated pulsatile left heart failure environments. The single volute and closed shroud impeller configuration exhibited lowest radial (0.01 N) and axial (3 N) force at nonpulsatile design flow conditions, respectively. Normal hemodynamic conditions of 5.1 L/min at 94 mm Hg were re-established upon inserting the device into the left heart failure environment, where the pump operated along the nonpulsatile characteristic curve for 2200 rpm. The operational limits on this curve were dictated by the required pressure differential across the pump during systolic and diastolic periods. The reduction of left atrial pressure (25 to 8 mm Hg) indicated the alleviation of pulmonary congestion. The ability for the LVAD to support circulation in a left heart failure environment was successfully demonstrated in the mock circulation loop. The impeller hydraulic force characteristics attained will aid the bearing designer to select the best volute and impeller configuration to minimize impeller touchdown in magnetic, hydrodynamic or mechanical type bearing applications. PMID:15982286

  12. Enabling Earth-Abundant Pyrite (FeS2) Semiconductor Nanostructures for High Performance Photovoltaic Devices

    SciTech Connect

    Jin, Song

    2014-11-18

    This project seeks to develop nanostructures of iron pyrite, an earth-abundant semiconductor, to enable their applications in high-performance photovoltaic (PV) devices. Growth of high purity iron pyrite nanostructures (nanowires, nanorods, and nanoplates), as well as iron pyrite thin films and single crystals, has been developed and their structures characterized. These structures have been fundamentally investigated to understand the origin of the low solar energy conversion efficiency of iron pyrite and various passivation strategies and doping approaches have been explored in order to improve it. By taking advantage of the high surface-to-bulk ratio in nanostructures and effective electrolyte gating, we fully characterized both the surface inversion and bulk electrical transport properties for the first time through electrolyte-gated Hall measurements of pyrite nanoplate devices and show that pyrite is n-type in the bulk and p-type near the surface due to strong inversion, which has important consequences to using nanocrystalline pyrite for efficient solar energy conversion. Furthermore, through a comprehensive investigation on n-type iron pyrite single crystals, we found the ionization of high-density bulk deep donor states, likely resulting from bulk sulfur vacancies, creates a non-constant charge distribution and a very narrow surface space charge region that limits the total barrier height, thus satisfactorily explains the limited photovoltage and poor photoconversion efficiency of iron pyrite single crystals. These findings suggest new ideas on how to improve single crystal pyrite and nanocrystalline or polycrystalline pyrite films to enable them for high performance solar applications.

  13. Effects of nanostructure geometry on polymer chain alignment and device performance in nanoimprinted polymer solar cell

    NASA Astrophysics Data System (ADS)

    Yang, Yi; Mielczarek, Kamil; Zakhidov, Anvar; Hu, Walter

    2013-03-01

    Among the various organic photovoltaic devices, the conjugated polymer/fullerene approach has drawn the most research interest. The performance of these types of solar cells is greatly determined by the nanoscale morphology of the two components (donor/acceptor) and the molecular orientation/crystallinity in the photoactive layer. This article demonstrates our recent studies on the nanostructure geometry effects on the nanoimprint induced poly(3 hexylthiophene-2,5-diyl) (P3HT) chain alignment and photovoltaic performance. Out-of-plane and in-plane grazing incident X-ray diffractions are employed to characterize the chain orientations in P3HT nanogratings with different widths and heights. It is found that nanoimprint procedure changes the initial edge-on alignment in non-imprinted P3HT thin film to a vertical orientation which favors the hole transport, with an organization height H≥ 170 nm and width in the range of 60 nm<= W< 210 nm. Samples with better aligned molecules lead to a larger crystallite sizes as well. Imprinted P3HT/[6,6]-penyl-C61-butyric-acid-methyl-ester (PCBM) solar cells show an increase in power conversion efficiency (PCE) with the decrease of nanostructure width, and with the increase of height and junction area. Devices with the highest PCE are made by the fully aligned and highest P3HT nanostructures (width w= 60 nm, height h= 170 nm), allowing for the most efficient charge separation, transport and light absorption. We believe this work will contribute to the optimal geometry design of nanoimprinted polymer solar cells.

  14. Force production during squats performed with a rotational resistance device under stable versus unstable conditions

    PubMed Central

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-01-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases. PMID:26696707

  15. Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

    PubMed

    Moras, Gerard; Vázquez-Guerrero, Jairo

    2015-11-01

    [Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases. PMID:26696707

  16. Evaluating the Performance of the NASA LaRC CMF Motion Base Safety Devices

    NASA Technical Reports Server (NTRS)

    Gupton, Lawrence E.; Bryant, Richard B., Jr.; Carrelli, David J.

    2006-01-01

    This paper describes the initial measured performance results of the previously documented NASA Langley Research Center (LaRC) Cockpit Motion Facility (CMF) motion base hardware safety devices. These safety systems are required to prevent excessive accelerations that could injure personnel and damage simulator cockpits or the motion base structure. Excessive accelerations may be caused by erroneous commands or hardware failures driving an actuator to the end of its travel at high velocity, stepping a servo valve, or instantly reversing servo direction. Such commands may result from single order failures of electrical or hydraulic components within the control system itself, or from aggressive or improper cueing commands from the host simulation computer. The safety systems must mitigate these high acceleration events while minimizing the negative performance impacts. The system accomplishes this by controlling the rate of change of valve signals to limit excessive commanded accelerations. It also aids hydraulic cushion performance by limiting valve command authority as the actuator approaches its end of travel. The design takes advantage of inherent motion base hydraulic characteristics to implement all safety features using hardware only solutions.

  17. Numerical analysis and experiment research on fluid orbital performance of vane type propellant management device

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Li, Y.; Pan, H. L.; Liu, J. T.; Zhuang, B. T.

    2015-01-01

    Vane type propellant management device (PMD) is one of the key components of the vane-type surface tension tank (STT), and its fluid orbital performance directly determines the STT's success or failure. In present paper, numerical analysis and microgravity experiment study on fluid orbital performance of a vane type PMD were carried out. By using two-phase flow model of volume of fluid (VOF), fluid flow characteristics in the tank with the vane type PMD were numerically calculated, and the rules of fluid transfer and distribution were gotten. A abbreviate model test system of the vane type PMD is established and microgravity drop tower tests were performed, then fluid management and transmission rules of the vane type PMD were obtained under microgravity environment. The analysis and tests results show that the vane type PMD has good and initiative fluid orbital management ability and meets the demands of fluid orbital extrusion in the vane type STT. The results offer valuable guidance for the design and optimization of the new generation of vane type PMD, and also provide a new approach for fluid management and control in space environment.

  18. Assessing performance of manufactured treatment devices for the removal of phosphorus from urban stormwater.

    PubMed

    Sample, David J; Grizzard, Thomas J; Sansalone, John; Davis, Allen P; Roseen, Robert M; Walker, Jane

    2012-12-30

    Nutrients such as nitrogen and phosphorus in urban runoff can be controlled through a variety of nonstructural and structural controls commonly known as best management practices (BMPs). Manufactured treatment devices (MTDs) are structural BMPs that may be used in portions of a site, often when space is limited. MTDs use a variety of technologies to achieve potentially greater treatment efficiency while reducing spatial requirements. However, verifying the performance of MTDs is difficult because of the variability of runoff water quality, the variability in treatment technologies, and the lack of standardized protocols for field testing. Performance testing of MTDs has focused almost exclusively upon removal of sediment; however MTDs are now being applied to the task of removing other constituents of concern, including nutrients such as phosphorus. This paper reviews current methods of assessing treatment performance of MTDs and introduces the Virginia Technology Assessment Protocol (VTAP), a program developed to evaluate the removal of phosphorus by MTDs. The competing goals of various stakeholders were considered when developing the VTAP. A conceptual framework of the tradeoffs considered is presented; these tradeoffs require compromise among the competing interests in order that innovation proceeds and benefits accrue. The key strengths of VTAP are also presented and compared with other existing programs. PMID:23079117

  19. Drift-Diffusion Modeling of the Effects of Structural Disorder and Carrier Mobility on the Performance of Organic Photovoltaic Devices

    NASA Astrophysics Data System (ADS)

    Finck, Benjamin Y.; Schwartz, Benjamin J.

    2015-09-01

    We probe the effects of structural disorder on the performance of organic photovoltaic (OPV) devices via drift-diffusion modeling. We utilize ensembles of spatially disordered one-dimensional mobility profiles to approximate the three-dimensional structural disorder present in actual devices. Each replica in our ensemble approximates one high-conductivity pathway through the three-dimensional network(s) present in a polymer-based bulk heterojunction solar cell, so that the ensemble-averaged behavior provides a good approximation to a full three-dimensional structurally disordered device. Our calculations show that the short-circuit current, fill factor, and power conversion efficiency of simulated devices are all negatively impacted by the inclusion of structural disorder, but that the open-circuit voltage is nearly impervious to structural defects. This is in contrast to energetic disorder, where previous studies found that spatial variation in the energy in OPV active layers causes a decrease in the open-circuit voltage. We also show that structural disorder causes the greatest detriment to device performance for feature sizes between 2 and 10 nm. Since this is on the same length scale as the fullerene crystallites in experimental devices, it suggests both that controlling structural disorder is critical to the performance of OPV devices and that the effects of structural disorder should be included in future drift-diffusion modeling studies of organic solar cells.

  20. Severe hypoxia affects exercise performance independently of afferent feedback and peripheral fatigue.

    PubMed

    Millet, Guillaume Y; Muthalib, Makii; Jubeau, Marc; Laursen, Paul B; Nosaka, Kazunori

    2012-04-01

    To test the hypothesis that hypoxia centrally affects performance independently of afferent feedback and peripheral fatigue, we conducted two experiments under complete vascular occlusion of the exercising muscle under different systemic O(2) environmental conditions. In experiment 1, 12 subjects performed repeated submaximal isometric contractions of the elbow flexor to exhaustion (RCTE) with inspired O(2) fraction fixed at 9% (severe hypoxia, SevHyp), 14% (moderate hypoxia, ModHyp), 21% (normoxia, Norm), or 30% (hyperoxia, Hyper). The number of contractions (performance), muscle (biceps brachii), and prefrontal near-infrared spectroscopy (NIRS) parameters and high-frequency paired-pulse (PS100) evoked responses to electrical muscle stimulation were monitored. In experiment 2, 10 subjects performed another RCTE in SevHyp and Norm conditions in which the number of contractions, biceps brachii electromyography responses to electrical nerve stimulation (M wave), and transcranial magnetic stimulation responses (motor-evoked potentials, MEP, and cortical silent period, CSP) were recorded. Performance during RCTE was significantly reduced by 10-15% in SevHyp (arterial O(2) saturation, SpO(2) = ∼75%) compared with ModHyp (SpO(2) = ∼90%) or Norm/Hyper (SpO(2) > 97%). Performance reduction in SevHyp occurred despite similar 1) metabolic (muscle NIRS parameters) and functional (changes in PS100 and M wave) muscle states and 2) MEP and CSP responses, suggesting comparable corticospinal excitability and spinal and cortical inhibition between SevHyp and Norm. It is concluded that, in SevHyp, performance and central drive can be altered independently of afferent feedback and peripheral fatigue. It is concluded that submaximal performance in SevHyp is partly reduced by a mechanism related directly to brain oxygenation. PMID:22323647

  1. Performance level affects the dietary supplement intake of both individual and team sports athletes.

    PubMed

    Giannopoulou, Ifigenia; Noutsos, Kostantinos; Apostolidis, Nikolaos; Bayios, Ioannis; Nassis, George P

    2013-01-01

    Dietary supplement (DS) intake is high in elite level athletes, however few studies have investigated the impact that the performance level of the athletes has on supplementation intake in individual and team sports. The purpose of the study was to determine and compare the DS intake among individual and team sport athletes of various performance levels. A total of 2845 participants (athletes: 2783, controls: 62) between the ages of 11 and 44 years old participated in the study. A 3-page questionnaire was developed to assess the intake of DS. Athletes were categorized based on participation in individual (n = 775) and team sports (n = 2008). To assess the effect of performance level in supplementation intake, athletes were categorized based on training volume, participation in the national team, and winning at least one medal in provincial, national, international or Olympic games. Overall, 37% of all athletes of various performance levels reported taking at least one DS in the last month. A higher prevalence of DS intake was reported in individual (44%) compared to team sport athletes (35%) (p < 0.001). Athletes of high performance level reported greater DS intake compared to lower performance athletes. Males reported a significantly greater prevalence of DS intake compared to females. The most popular supplement reported was amino acid preparation with the main reason of supplementation being endurance improvements. In conclusion, performance level and type of sport appear to impact the DS practices of male and female athletes. These findings should be validated in other populations. Key points37% of Mediterranean athletes of various sports and levels have reported taking dietary supplements.The performance level of the athletes affects the dietary supplementation intake.Athletes in individual sports appear to have a higher DS intake compared to team sport athletes.Male athletes appear to take more dietary supplements compared to female athletes. PMID:24149744

  2. 40 CFR Table 3 to Subpart Mmmmm of... - Performance Test Requirements for New or Reconstructed Flame Lamination Affected Sources

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... or Reconstructed Flame Lamination Affected Sources 3 Table 3 to Subpart MMMMM of Part 63 Protection... Lamination Affected Sources As stated in § 63.8800, you must comply with the requirements for performance tests for new or reconstructed flame lamination affected sources in the following table using...

  3. The Functional Effect of Teacher Positive and Neutral Affect on Task Performance of Students with Significant Disabilities

    ERIC Educational Resources Information Center

    Park, Sungho; Singer, George H. S.; Gibson, Mary

    2005-01-01

    The study uses an alternating treatment design to evaluate the functional effect of teacher's affect on students' task performance. Tradition in special education holds that teachers should engage students using positive and enthusiastic affect for task presentations and praise. To test this assumption, we compared two affective conditions. Three…

  4. How Does the Driver’s Perception Reaction Time Affect the Performances of Crash Surrogate Measures?

    PubMed Central

    Kuang, Yan; Qu, Xiaobo; Weng, Jinxian; Etemad-Shahidi, Amir

    2015-01-01

    With the merit on representing traffic conflict through examining the crash mechanism and causality proactively, crash surrogate measures have long been proposed and applied to evaluate the traffic safety. However, the driver’s Perception-Reaction Time (PRT), an important variable in crash mechanism, has not been considered widely into surrogate measures. In this regard, it is important to know how the PRT affects the performances of surrogate indicators. To this end, three widely used surrogate measures are firstly modified by involving the PRT into their crash mechanisms. Then, in order to examine the difference caused by the PRT, a comparative study is carried out on a freeway section of the Pacific Motorway, Australia. This result suggests that the surrogate indicators’ performances in representing rear-end crash risks are improved with the incorporating of the PRT for the investigated section. PMID:26398416

  5. Individual Differences in School Mathematics Performance and Feelings of Difficulty: The Effects of Cognitive Ability, Affect, Age, and Gender.

    ERIC Educational Resources Information Center

    Efklides, Anastasia; Papadaki, Maria; Papantoniou, Georgia; Kiosseoglou, Gregoris

    1999-01-01

    Explores possible individual differences effects on school mathematics performance and feelings of difficulty (FOD) of 243 subjects, ages 13 to 15 years. Considers cognitive ability, affect, age, and gender. Finds that ability directly influenced performance whereas both ability and affect influenced FOD. Discusses the results. (CMK)

  6. Cognition-Based and Affect-Based Trust as Mediators of Leader Behavior Influences on Team Performance

    ERIC Educational Resources Information Center

    Schaubroeck, John; Lam, Simon S. K.; Peng, Ann Chunyan

    2011-01-01

    We develop a model in which cognitive and affective trust in the leader mediate the relationship between leader behavior and team psychological states that, in turn, drive team performance. The model is tested on a sample of 191 financial services teams in Hong Kong and the U.S. Servant leadership influenced team performance through affect-based…

  7. Ambient temperature: a factor affecting performance and physiological response of broiler chickens

    NASA Astrophysics Data System (ADS)

    Donkoh, A.

    1989-12-01

    An experiment was conducted to elucidate the influence of four constant ambient temperatures (20°, 25°, 30° and 35°C) on the performance and physiological reactions of male commercial broiler chicks from 3 to 7 weeks of age. A 12 h light-dark cycle was operated, while relative humidity and air circulation were not controlled. Exposure of broiler chickens to the 20°, 25°, 30° and 35°C treatments showed highly significant ( P<0.0001) depression in growth rate, food intake and efficiency of food utilization, and a significant increase in water consumption for the 30° and 35°C groups. Mortality was, however, not affected by the temperature treatments. Changes in physiological status, such as increased rectal temperatures, decreased concentration of red blood cells, haemoglobin, haematocrit, and total plasma protein were observed in birds housed in the higher temperature (30° and 35°C) environments. Moreover, in these broiler chickens, there was an increased blood glucose concentration and a decreased thyroid gland weight. These results indicate that continuous exposure of broiler chickens to high ambient temperatures markedly affects their performance and physiological response.

  8. Effect of self-similar traffic on the performance and buffer requirements of ATM ABR edge devices

    SciTech Connect

    Dastangoo, S.; Miller, G.J.; Chen, H.; Brandt, J.

    1996-02-05

    Previous studies demonstrated that Ethemet local area network traffic is statistically self-similar and that the commonly used Poisson models are not able to capture the fractal characteristics of Ethemet traffic. This contribution uses simulated self-similar traffic traces from the MITRE Corporation and Sandia`s simulation software to evaluate the ABR performance of an ATM backbone. The ATM backbone interconnects Ethemet LANs via edge devices such as routers and bridges. We evaluate the overall network performance in terms of throughput, response time, fairness, and buffer requirements. Because typical edge devices perform simple forwarding functions, their usual mechanism for signaling network congestion is packet dropping. Therefore, we believe that the proper provisioning of buffer resources in ATM edge devices is crucial to the overall network performance.

  9. Performance characteristics of high-resolution charge-coupled device film digitizers

    NASA Astrophysics Data System (ADS)

    Lo, Shih-Chung B.; Butson, Philip D.; Lin, Jyh-Shyan; Li, Huai; Freedman, Matthew T.; Mun, Seong K.

    1995-05-01

    This paper describes the performance characteristics of two high resolution charged-coupled device (CCD) film scanners for radiological imaging. The two models of recently developed CCD film scanners made by DBA Systems have been available on the market for ultra high resolution film digitization. One model of the scanner digitizes the film at 21 micrometers and the other one at 42 micrometers . Both systems can be interfaced to a PC. Line-pair, star-pattern and single edge on films were used to test the spatial resolution in the directions perpendicular and parallel to the CCD scan line. Step wedges generated on films through a mammographic system and print transparencies were employed to test the gray value versus the optical density response and variations on a `uniform area.' Geometric distortion of the digitized images was determined to be negligible at less than 1%. This gray value versus optical density response was linearly plotted from optical density (OD) 0 to 2.8. Depending upon optical density regions, gray value fluctuations varied. Both ultra high resolution CCD scanners showed reasonable performance. However, some digital noises were shown in the high OD range.

  10. Portable electro-optic device for performing serviceability check on IR guided missiles

    NASA Astrophysics Data System (ADS)

    Maini, A. K.; Agrawal, V.

    2009-09-01

    Electro-optically guided weapons are the most potent and widely used munitions on land-based, aerial and ship-borne platforms because of their proven precision strike capability. Two such guided weapon categories include the IR guided surface-to-air and air-to-air missiles and laser guided bombs and missiles. The efficacy of the mission is critically dependent on the successful deployment of the weapon. This not only necessitates that periodic functionality check be carried out on these weapons, it should also be possible to perform functionality check also known as serviceability check even after they are strapped on to the launch platform. Serviceability check in the strap-on condition ensures a much higher hit probability. This paper presents the design and development of a portable electro-optic device that generates IR signatures in 3-5-µm band having the desired amplitude and spectral shape to match the IR signatures of target aircraft. A prototype was built using the proposed concept. The prototype was characterized in terms of its output amplitude and wavelength spectrum. The prototype was used to perform serviceability check on IR seekers of foreign origin. Test results are presented in the paper.

  11. The Effect of Surface Morphology on Corrosion Performance of SS 316 LVM Biomedical Devices

    NASA Astrophysics Data System (ADS)

    Toloei, Alisina; Guo, Mengnan; Rotermund, Harm H.

    2015-10-01

    In this study, in order to investigate the relationship between surface roughness and the corrosion resistance of the SS 316 LVM wires, samples have been prepared with different surface roughness by using different grits of SiC papers. In order to simulate the environment of implanted biomedical devices, a three-electrode electrochemical cell with 0.9% (by mass) NaCl solution has been used to test the corrosion resistance of the samples by potentiodynamic method and anodic polarization tests. SEM, EDS, and XPS have been performed to analyze the surfaces appearance and chemical elements on the surface before and after the corrosion. AFM was also used to get 3D images of the surface and to show the change in roughness of the samples after corrosion testing. Background-subtracted contrast-enhanced microscopy has been performed in situ to detect the pitting process happening on the surface of stainless steel samples. It was concluded that a relatively smoother surface can result in higher corrosion resistance and larger potential of stable pitting, whereas a rougher surface can easily go into stable pitting with lower pitting potentials. Rougher surfaces also showed a shorter time for the formation of stable pits. Microscopy observations illustrated more corrosion on rougher surfaces, and EDS showed more chloride ion remained on these surfaces.

  12. TiNi-based films for elastocaloric microcooling— Fatigue life and device performance

    NASA Astrophysics Data System (ADS)

    Ossmer, H.; Chluba, C.; Kauffmann-Weiss, S.; Quandt, E.; Kohl, M.

    2016-06-01

    The global trend of miniaturization and concomitant increase of functionality in microelectronics, microoptics, and various other fields in microtechnology leads to an emerging demand for temperature control at small scales. In this realm, elastocaloric cooling is an interesting alternative to thermoelectrics due to the large latent heat and good down-scaling behavior. Here, we investigate the elastocaloric effect due to a stress-induced phase transformation in binary TiNi and quaternary TiNiCuCo films of 20 μm thickness produced by DC magnetron sputtering. The mesoscale mechanical and thermal performance, as well as the fatigue behavior are studied by uniaxial tensile tests combined with infrared thermography and digital image correlation measurements. Binary films exhibit strong features of fatigue, involving a transition from Lüders-like to homogeneous transformation behavior within three superelastic cycles. Quaternary films, in contrast, show stable Lüders-like transformation without any signs of degradation. The elastocaloric temperature change under adiabatic conditions is -15 K and -12 K for TiNi and TiNiCuCo films, respectively. First-of-its-kind heat pump demonstrators are developed that make use of out-of-plane deflection of film bridges. Owing to their large surface-to-volume ratio, the demonstrators reveal rapid heat transfer. The TiNiCuCo-based devices, for instance, generate a temperature difference of 3.5 K within 13 s. The coefficients of performance of the demonstrators are about 3.

  13. Performance of a parallel algebraic multilevel preconditioner for stabilized finite element semiconductor device modeling

    SciTech Connect

    Lin, Paul T. Shadid, John N.; Sala, Marzio; Tuminaro, Raymond S.; Hennigan, Gary L.; Hoekstra, Robert J.

    2009-09-20

    In this study results are presented for the large-scale parallel performance of an algebraic multilevel preconditioner for solution of the drift-diffusion model for semiconductor devices. The preconditioner is the key numerical procedure determining the robustness, efficiency and scalability of the fully-coupled Newton-Krylov based, nonlinear solution method that is employed for this system of equations. The coupled system is comprised of a source term dominated Poisson equation for the electric potential, and two convection-diffusion-reaction type equations for the electron and hole concentration. The governing PDEs are discretized in space by a stabilized finite element method. Solution of the discrete system is obtained through a fully-implicit time integrator, a fully-coupled Newton-based nonlinear solver, and a restarted GMRES Krylov linear system solver. The algebraic multilevel preconditioner is based on an aggressive coarsening graph partitioning of the nonzero block structure of the Jacobian matrix. Representative performance results are presented for various choices of multigrid V-cycles and W-cycles and parameter variations for smoothers based on incomplete factorizations. Parallel scalability results are presented for solution of up to 10{sup 8} unknowns on 4096 processors of a Cray XT3/4 and an IBM POWER eServer system.

  14. Performance of a parallel algebraic multilevel preconditioner for stabilized finite element semiconductor device modeling

    NASA Astrophysics Data System (ADS)

    Lin, Paul T.; Shadid, John N.; Sala, Marzio; Tuminaro, Raymond S.; Hennigan, Gary L.; Hoekstra, Robert J.

    2009-09-01

    In this study results are presented for the large-scale parallel performance of an algebraic multilevel preconditioner for solution of the drift-diffusion model for semiconductor devices. The preconditioner is the key numerical procedure determining the robustness, efficiency and scalability of the fully-coupled Newton-Krylov based, nonlinear solution method that is employed for this system of equations. The coupled system is comprised of a source term dominated Poisson equation for the electric potential, and two convection-diffusion-reaction type equations for the electron and hole concentration. The governing PDEs are discretized in space by a stabilized finite element method. Solution of the discrete system is obtained through a fully-implicit time integrator, a fully-coupled Newton-based nonlinear solver, and a restarted GMRES Krylov linear system solver. The algebraic multilevel preconditioner is based on an aggressive coarsening graph partitioning of the nonzero block structure of the Jacobian matrix. Representative performance results are presented for various choices of multigrid V-cycles and W-cycles and parameter variations for smoothers based on incomplete factorizations. Parallel scalability results are presented for solution of up to 108 unknowns on 4096 processors of a Cray XT3/4 and an IBM POWER eServer system.

  15. Initial Clinical Experience Performing Patient Treatment Verification With an Electronic Portal Imaging Device Transit Dosimeter

    SciTech Connect

    Berry, Sean L.; Polvorosa, Cynthia; Cheng, Simon; Deutsch, Israel; Chao, K. S. Clifford; Wuu, Cheng-Shie

    2014-01-01

    Purpose: To prospectively evaluate a 2-dimensional transit dosimetry algorithm's performance on a patient population and to analyze the issues that would arise in a widespread clinical adoption of transit electronic portal imaging device (EPID) dosimetry. Methods and Materials: Eleven patients were enrolled on the protocol; 9 completed and were analyzed. Pretreatment intensity modulated radiation therapy (IMRT) patient-specific quality assurance was performed using a stringent local 3%, 3-mm γ criterion to verify that the planned fluence had been appropriately transferred to and delivered by the linear accelerator. Transit dosimetric EPID images were then acquired during treatment and compared offline with predicted transit images using a global 5%, 3-mm γ criterion. Results: There were 288 transit images analyzed. The overall γ pass rate was 89.1% ± 9.8% (average ± 1 SD). For the subset of images for which the linear accelerator couch did not interfere with the measurement, the γ pass rate was 95.7% ± 2.4%. A case study is presented in which the transit dosimetry algorithm was able to identify that a lung patient's bilateral pleural effusion had resolved in the time between the planning CT scan and the treatment. Conclusions: The EPID transit dosimetry algorithm under consideration, previously described and verified in a phantom study, is feasible for use in treatment delivery verification for real patients. Two-dimensional EPID transit dosimetry can play an important role in indicating when a treatment delivery is inconsistent with the original plan.

  16. High-performance polymer semiconducting heterostructure devices by nitrene-mediated photocrosslinking of alkyl side chains.

    PubMed

    Png, Rui-Qi; Chia, Perq-Jon; Tang, Jie-Cong; Liu, Bo; Sivaramakrishnan, Sankaran; Zhou, Mi; Khong, Siong-Hee; Chan, Hardy S O; Burroughes, Jeremy H; Chua, Lay-Lay; Friend, Richard H; Ho, Peter K H

    2010-02-01

    Heterostructures are central to the efficient manipulation of charge carriers, excitons and photons for high-performance semiconductor devices. Although these can be formed by stepwise evaporation of molecular semiconductors, they are a considerable challenge for polymers owing to re-dissolution of the underlying layers. Here we demonstrate a simple and versatile photocrosslinking methodology based on sterically hindered bis(fluorophenyl azide)s. The photocrosslinking efficiency is high and dominated by alkyl side-chain insertion reactions, which do not degrade semiconductor properties. We demonstrate two new back-infiltrated and contiguous interpenetrating donor-acceptor heterostructures for photovoltaic applications that inherently overcome internal recombination losses by ensuring path continuity to give high carrier-collection efficiency. This provides the appropriate morphology for high-efficiency polymer-based photovoltaics. We also demonstrate photopatternable polymer-based field-effect transistors and light-emitting diodes, and highly efficient separate-confinement-heterostructure light-emitting diodes. These results open the way to the general development of high-performance polymer semiconductor heterostructures that have not previously been thought possible. PMID:19966791

  17. Science and technology of piezoelectric/diamond heterostructures for monolithically integrated high performance MEMS/NEMS/CMOS devices.

    SciTech Connect

    Auciello, O.; Sumant, A. V.; Hiller, J.; Kabius, B.; Ma, Z.; Srinivasan, S.

    2008-12-01

    This paper describes the fundamental and applied science performed to integrate piezoelectric PbZr{sub x}Ti{sub 1-x}O{sub 3} and AlN films with a novel mechanically robust ultrananocrystalline diamond layer to enable a new generation of low voltage/high-performance piezoactuated hybrid piezoelectric/diamond MEMS/NEMS devices.

  18. Red Color Light at Different Intensities Affects the Performance, Behavioral Activities and Welfare of Broilers.

    PubMed

    Senaratna, D; Samarakone, T S; Gunawardena, W W D A

    2016-07-01

    Red light (RL) marked higher weight gain (WG) and preference of broilers compared to other light colors. This study aimed to investigate how different intensities of RL affect the performance, behavior and welfare of broilers. RL treatments were T1 = high intensity (320 lux), T2 = medium intensity (20 lux); T3 = dim intensity (5 lux), T4 = control/white light at (20 lux) provided on 20L:4D schedule and T5 = negative control; 12 hours dark: 12 hours day light. Cobb strain broilers were used in a Complete Randomize Design with 6 replicates. WG, water/feed intake, feed conversion ratio (FCR), mortality, behavior and welfare were assessed. At 35 d, significantly (p<0.05) highest body weight (2,147.06 g±99) was recorded by T3. Lowest body weight (1,640.55 g±56) and FCR (1.34) were recorded by T5. Skin weight was the only carcass parameter showed a significant (p<0.05) influence giving the highest (56.2 g) and the lowest (12.6 g) values for T5 and T1 respectively. Reduced welfare status indicated by significantly (p<0.05) higher foot pad lesions, hock burns and breast blisters was found under T3, due to reduced expression of behavior. Highest walking (2.08%±1%) was performed under T1 in the evening during 29 to 35 days. Highest dust bathing (3.01%±2%) was performed in the morning during 22 to 28 days and highest bird interaction (BI) (4.87%±4%) was observed in the evening by T5 during 14 to 21 days. Light intensity×day session×age interaction was significantly (p<0.05) affected walking, dust bathing and BI. Light intensity significantly (p<0.05) affected certain behaviors such as lying, eating, drinking, standing, walking, preening while lying, wing/leg stretching, sleeping, dozing, BI, vocalization, idling. In conclusion, birds essentially required provision of light in the night for better performance. Exposed to 5 lux contributed to higher WG, potentially indicating compromised welfare status. Further researches are suggested to investigate RL intensity based

  19. Red Color Light at Different Intensities Affects the Performance, Behavioral Activities and Welfare of Broilers

    PubMed Central

    Senaratna, D.; Samarakone, T. S.; Gunawardena, W. W. D. A.

    2016-01-01

    Red light (RL) marked higher weight gain (WG) and preference of broilers compared to other light colors. This study aimed to investigate how different intensities of RL affect the performance, behavior and welfare of broilers. RL treatments were T1 = high intensity (320 lux), T2 = medium intensity (20 lux); T3 = dim intensity (5 lux), T4 = control/white light at (20 lux) provided on 20L:4D schedule and T5 = negative control; 12 hours dark: 12 hours day light. Cobb strain broilers were used in a Complete Randomize Design with 6 replicates. WG, water/feed intake, feed conversion ratio (FCR), mortality, behavior and welfare were assessed. At 35 d, significantly (p<0.05) highest body weight (2,147.06 g±99) was recorded by T3. Lowest body weight (1,640.55 g±56) and FCR (1.34) were recorded by T5. Skin weight was the only carcass parameter showed a significant (p<0.05) influence giving the highest (56.2 g) and the lowest (12.6 g) values for T5 and T1 respectively. Reduced welfare status indicated by significantly (p<0.05) higher foot pad lesions, hock burns and breast blisters was found under T3, due to reduced expression of behavior. Highest walking (2.08%±1%) was performed under T1 in the evening during 29 to 35 days. Highest dust bathing (3.01%±2%) was performed in the morning during 22 to 28 days and highest bird interaction (BI) (4.87%±4%) was observed in the evening by T5 during 14 to 21 days. Light intensity×day session×age interaction was significantly (p<0.05) affected walking, dust bathing and BI. Light intensity significantly (p<0.05) affected certain behaviors such as lying, eating, drinking, standing, walking, preening while lying, wing/leg stretching, sleeping, dozing, BI, vocalization, idling. In conclusion, birds essentially required provision of light in the night for better performance. Exposed to 5 lux contributed to higher WG, potentially indicating compromised welfare status. Further researches are suggested to investigate RL intensity based

  20. Effect of dual gate control on the alternating current performance of graphene radio frequency device

    NASA Astrophysics Data System (ADS)

    Zhu, Wenjuan; Low, Tony; Farmer, Damon B.; Jenkins, Keith; Ek, Bruce; Avouris, Phaedon

    2013-07-01

    The excellent electrical properties of graphene, such as its high carrier mobility, gate tunability, and mechanical flexibility makes it a very promising material for radio frequency (RF) electronics. Here we study the impact of top and bottom gate control on the essential performance metrics of graphene RF transistors. We find that the maximum cut-off frequency improves as the bottom gate voltage is tuned towards the same polarity as the top gate bias voltage. These results can be explained by the bottom-gate tunable doping of the graphene underneath the metal contacts and in the under-lap region. These effects become more dramatic with device down-scaling. We also find that the minimum output conductance occurs, when the drain voltage roughly equals an effective gate voltage (Veff≈VTG+VBGṡCBG/CTG, where VTG and VBG are top and bottom gate voltage, CTG and CBG are the respective gate capacitance). The minimum output conductance is reduced as the bottom gate bias increases, due to the stronger control of the channel from the bottom gate, lessening the influence of the drain voltage on the drain current. As a result of these two influences, when the bottom gate voltage is tuned towards the same polarity as the top gate voltage, both the maximum oscillation frequency (fmax) and the intrinsic gain significantly improve. The intrinsic gain can increase as high as 3-4 times as the gain without the bottom gate bias. Tuning the bottom gate to enhance fmax and gain will be very important elements in the effort to enable graphene RF devices for practical use.

  1. Effect of annealing treatment on the performance of organic photovoltaic devices using SPFGraphene as electron-accepter material

    NASA Astrophysics Data System (ADS)

    Wang, HaiTeng; He, DaWei; Wang, YongSheng; Liu, ZhiYong; Wu, HongPeng; Wang, JiGang; Zhao, Yu

    2012-08-01

    We have researched the performances of organic photovoltaic devices with the bulk heterojunction (BHJ) structure using the organic solution-processable functionalized graphene (SPFGraphene) material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT:PSS/P3OT:PCBM-SPFGraphene/LiF/Al. Given the P3OT/PCBM (1:1) mixture with 8wt% of SPFGraphene, the open-circuit voltage ( V oc) of the device reaches 0.64 V, a short-circuit current density ( J sc) reaches 5.7 mA/cm2, a fill factor ( FF) reaches 0.42, and the power conversion efficiency ( η) reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement. In the P3OT:PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital (LUMO)-SPFGraphene-Al. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital (HOMO) and LUMO of the donor/acceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180°C show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.

  2. Measures of GCM Performance as Functions of Model Parameters Affecting Clouds and Radiation

    NASA Astrophysics Data System (ADS)

    Jackson, C.; Mu, Q.; Sen, M.; Stoffa, P.

    2002-05-01

    This abstract is one of three related presentations at this meeting dealing with several issues surrounding optimal parameter and uncertainty estimation of model predictions of climate. Uncertainty in model predictions of climate depends in part on the uncertainty produced by model approximations or parameterizations of unresolved physics. Evaluating these uncertainties is computationally expensive because one needs to evaluate how arbitrary choices for any given combination of model parameters affects model performance. Because the computational effort grows exponentially with the number of parameters being investigated, it is important to choose parameters carefully. Evaluating whether a parameter is worth investigating depends on two considerations: 1) does reasonable choices of parameter values produce a large range in model response relative to observational uncertainty? and 2) does the model response depend non-linearly on various combinations of model parameters? We have decided to narrow our attention to selecting parameters that affect clouds and radiation, as it is likely that these parameters will dominate uncertainties in model predictions of future climate. We present preliminary results of ~20 to 30 AMIPII style climate model integrations using NCAR's CCM3.10 that show model performance as functions of individual parameters controlling 1) critical relative humidity for cloud formation (RHMIN), and 2) boundary layer critical Richardson number (RICR). We also explore various definitions of model performance that include some or all observational data sources (surface air temperature and pressure, meridional and zonal winds, clouds, long and short-wave cloud forcings, etc...) and evaluate in a few select cases whether the model's response depends non-linearly on the parameter values we have selected.

  3. Work-family enrichment and job performance: a constructive replication of affective events theory.

    PubMed

    Carlson, Dawn; Kacmar, K Michele; Zivnuska, Suzanne; Ferguson, Merideth; Whitten, Dwayne

    2011-07-01

    Based on affective events theory (AET), we hypothesize a four-step model of the mediating mechanisms of positive mood and job satisfaction in the relationship between work-family enrichment and job performance. We test this model for both directions of enrichment (work-to-family and family-to-work). We used two samples to test the model using structural equation modeling. Results from Study 1, which included 240 full-time employees, were replicated in Study 2, which included 189 matched subordinate-supervisor dyads. For the work-to-family direction, results from both samples support our conceptual model and indicate mediation of the enrichment-performance relationship for the work-to-family direction of enrichment. For the family-to-work direction, results from the first sample support our conceptual model but results from the second sample do not. Our findings help elucidate mixed findings in the enrichment and job performance literatures and contribute to an understanding of the mechanisms linking these concepts. We conclude with a discussion of the practical and theoretical implications of our findings. PMID:21728437

  4. Nectar resource limitation affects butterfly flight performance and metabolism differently in intensive and extensive agricultural landscapes.

    PubMed

    Lebeau, Julie; Wesselingh, Renate A; Van Dyck, Hans

    2016-05-11

    Flight is an essential biological ability of many insects, but is energetically costly. Environments under rapid human-induced change are characterized by habitat fragmentation and may impose constraints on the energy income budget of organisms. This may, in turn, affect locomotor performance and willingness to fly. We tested flight performance and metabolic rates in meadow brown butterflies (Maniola jurtina) of two contrasted agricultural landscapes: intensively managed, nectar-poor (IL) versus extensively managed, nectar-rich landscapes (EL). Young female adults were submitted to four nectar treatments (i.e. nectar quality and quantity) in outdoor flight cages. IL individuals had better flight capacities in a flight mill and had lower resting metabolic rates (RMR) than EL individuals, except under the severest treatment. Under this treatment, RMR increased in IL individuals, but decreased in EL individuals; flight performance was maintained by IL individuals, but dropped by a factor 2.5 in EL individuals. IL individuals had more canalized (i.e. less plastic) responses relative to the nectar treatments than EL individuals. Our results show significant intraspecific variation in the locomotor and metabolic response of a butterfly to different energy income regimes relative to the landscape of origin. Ecophysiological studies help to improve our mechanistic understanding of the eco-evolutionary impact of anthropogenic environments on rare and widespread species. PMID:27147100

  5. Performance of large electron energy filter in large volume plasma device

    SciTech Connect

    Singh, S. K.; Srivastava, P. K.; Awasthi, L. M.; Mattoo, S. K.; Sanyasi, A. K.; Kaw, P. K.; Singh, R.

    2014-03-15

    This paper describes an in-house designed large Electron Energy Filter (EEF) utilized in the Large Volume Plasma Device (LVPD) [S. K. Mattoo, V. P. Anita, L. M. Awasthi, and G. Ravi, Rev. Sci. Instrum. 72, 3864 (2001)] to secure objectives of (a) removing the presence of remnant primary ionizing energetic electrons and the non-thermal electrons, (b) introducing a radial gradient in plasma electron temperature without greatly affecting the radial profile of plasma density, and (c) providing a control on the scale length of gradient in electron temperature. A set of 19 independent coils of EEF make a variable aspect ratio, rectangular solenoid producing a magnetic field (B{sub x}) of 100 G along its axis and transverse to the ambient axial field (B{sub z} ∼ 6.2 G) of LVPD, when all its coils are used. Outside the EEF, magnetic field reduces rapidly to 1 G at a distance of 20 cm from the center of the solenoid on either side of target and source plasma. The EEF divides LVPD plasma into three distinct regions of source, EEF and target plasma. We report that the target plasma (n{sub e} ∼ 2 × 10{sup 11} cm{sup −3} and T{sub e} ∼ 2 eV) has no detectable energetic electrons and the radial gradients in its electron temperature can be established with scale length between 50 and 600 cm by controlling EEF magnetic field. Our observations reveal that the role of the EEF magnetic field is manifested by the energy dependence of transverse electron transport and enhanced transport caused by the plasma turbulence in the EEF plasma.

  6. Cybersecurity Regulation of Wireless Devices for Performance and Assurance in the Age of "Medjacking".

    PubMed

    Armstrong, David G; Kleidermacher, David N; Klonoff, David C; Slepian, Marvin J

    2016-03-01

    We are rapidly reaching a point where, as connected devices for monitoring and treating diabetes and other diseases become more pervasive and powerful, the likelihood of malicious medical device hacking (known as "medjacking") is growing. While government could increase regulation, we have all been witness in recent times to the limitations and issues surrounding exclusive reliance on government. Herein we outline a preliminary framework for establishing security for wireless health devices based on international common criteria. Creation of an independent medical device cybersecurity body is suggested. The goal is to allow for continued growth and innovation while simultaneously fostering security, public trust, and confidence. PMID:26319227

  7. Cybersecurity Regulation of Wireless Devices for Performance and Assurance in the Age of “Medjacking”

    PubMed Central

    Armstrong, David G.; Kleidermacher, David N.; Klonoff, David C.; Slepian, Marvin J.

    2015-01-01

    We are rapidly reaching a point where, as connected devices for monitoring and treating diabetes and other diseases become more pervasive and powerful, the likelihood of malicious medical device hacking (known as “medjacking”) is growing. While government could increase regulation, we have all been witness in recent times to the limitations and issues surrounding exclusive reliance on government. Herein we outline a preliminary framework for establishing security for wireless health devices based on international common criteria. Creation of an independent medical device cybersecurity body is suggested. The goal is to allow for continued growth and innovation while simultaneously fostering security, public trust, and confidence. PMID:26319227

  8. Factors affecting the performance of microbial fuel cells for sulfur pollutants removal.

    PubMed

    Zhao, Feng; Rahunen, Nelli; Varcoe, John R; Roberts, Alexander J; Avignone-Rossa, Claudio; Thumser, Alfred E; Slade, Robert C T

    2009-03-15

    A microbial fuel cell (MFC) has been developed for removal of sulfur-based pollutants and can be used for simultaneous wastewater treatment and electricity generation. This fuel cell uses an activated carbon cloth+carbon fibre veil composite anode, air-breathing dual cathodes and the sulfate-reducing species Desulfovibrio desulfuricans. 1.16gdm(-3) sulfite and 0.97gdm(-3) thiosulfate were removed from the wastewater at 22 degrees C, representing sulfite and thiosulfate removal conversions of 91% and 86%, respectively. The anode potential was controlled by the concentration of sulfide in the compartment. The performance of the cathode assembly was affected by the concentration of protons in the cation-exchanging ionomer with which the electrocatalyst is co-bound at the three-phase (air, catalyst and support) boundary. PMID:19022647

  9. Spatial environmental heterogeneity affects plant growth and thermal performance on a green roof.

    PubMed

    Buckland-Nicks, Michael; Heim, Amy; Lundholm, Jeremy

    2016-05-15

    Green roofs provide ecosystem services, including stormwater retention and reductions in heat transfer through the roof. Microclimates, as well as designed features of green roofs, such as substrate and vegetation, affect the magnitude of these services. Many green roofs are partially shaded by surrounding buildings, but the effects of this within-roof spatial environmental heterogeneity on thermal performance and other ecosystem services have not been examined. We quantified the effects of spatial heterogeneity in solar radiation, substrate depth and other variables affected by these drivers on vegetation and ecosystem services in an extensive green roof. Spatial heterogeneity in substrate depth and insolation were correlated with differential growth, survival and flowering in two focal plant species. These effects were likely driven by the resulting spatial heterogeneity in substrate temperature and moisture content. Thermal performance (indicated by heat flux and substrate temperature) was influenced by spatial heterogeneity in vegetation cover and substrate depth. Areas with less insolation were cooler in summer and had greater substrate moisture, leading to more favorable conditions for plant growth and survival. Spatial variation in substrate moisture (7%-26% volumetric moisture content) and temperature (21°C-36°C) during hot sunny conditions in summer could cause large differences in stormwater retention and heat flux within a single green roof. Shaded areas promote smaller heat fluxes through the roof, leading to energy savings, but lower evapotranspiration in these areas should reduce stormwater retention capacity. Spatial heterogeneity can thus result in trade-offs between different ecosystem services. The effects of these spatial heterogeneities are likely widespread in green roofs. Structures that provide shelter from sun and wind may be productively utilized to design higher functioning green roofs and increase biodiversity by providing habitat

  10. Motion and emotion: depression reduces psychomotor performance and alters affective movements in caregiving interactions

    PubMed Central

    Young, Katherine S.; Parsons, Christine E.; Stein, Alan; Kringelbach, Morten L.

    2015-01-01

    Background: Impaired social functioning is a well-established feature of depression. Evidence to date suggests that disrupted processing of emotional cues may constitute part of this impairment. Beyond processing of emotional cues, fluent social interactions require that people physically move in synchronized, contingent ways. Disruptions to physical movements are a diagnostic feature of depression (psychomotor disturbance) but have not previously been assessed in the context of social functioning. Here we investigated the impact of psychomotor disturbance in depression on physical responsive behavior in both an experimental and observational setting. Methods: In Experiment 1, we examined motor disturbance in depression in response to salient emotional sounds, using a laboratory-based effortful motor task. In Experiment 2, we explored whether psychomotor disturbance was apparent in real-life social interactions. Using mother-infant interactions as a model affective social situation, we compared physical behaviors of mothers with and without postnatal depression (PND). Results: We found impairments in precise, controlled psychomotor performance in adults with depression relative to healthy adults (Experiment 1). Despite this disruption, all adults showed enhanced performance following exposure to highly salient emotional cues (infant cries). Examining real-life interactions, we found differences in physical movements, namely reduced affective touching, in mothers with PND responding to their infants, compared to healthy mothers (Experiment 2). Conclusions: Together, these findings suggest that psychomotor disturbance may be an important feature of depression that can impair social functioning. Future work investigating whether improvements in physical movement in depression could have a positive impact on social interactions would be of much interest. PMID:25741255

  11. How do radiographic techniques affect mass lesion detection performance in digital mammography?

    NASA Astrophysics Data System (ADS)

    Huda, Walter; Ogden, Kent M.; Scalzetti, Ernest M.; Dudley, Eric F.; Dance, David R.

    2004-05-01

    We investigated how the x-ray tube kV and mAs affected the detection of simulated lesions with diameters between 0.24 and 12 mm. Digital mammograms were acquired with and without mass lesions, permitting a difference image to be generated corresponding to the lesion alone. Isolated digital lesions were added at a reduced intensity to non-lesion images, and used in Four-Alternate Forced Choice (4-AFC) experiments to determine the lesion intensity that corresponded to an accuracy of 92% (I92%). Values of I92% were determined at x-ray tube output values ranging from 40 to 120 mAs, and x-ray tube voltages ranging from 24 to 32 kV. For mass lesions larger than ~0.8 mm, there was no significant change in detection peformance with changing mAs. Doubling of the x-ray tube output from 60 to 120 mAs resulted in an average change in I92% of only +3.8%, whereas the Rose model of lesion detection predicts a reduction in the experimental value of I92% of -29%. For the 0.24 mm lesion, however, reducing the x-ray beam mAs from 100 to 40 mAs reduced the average detection performance by ~60%. Contrast-detail curves for lesions with diameter >= 0.8 mm had a slope of ~+0.23, whereas the Rose model predicts a slope of -0.5. For lesions smaller than ~0.8 mm, contrast-detail slopes were all negative with the average gradient increasing with decreasing mAs value. Increasing the x-ray tube voltage from 24 to 32 kV at a constant display contrast resulted in a modest improvement in low contrast lesion detection performance of ~10%. Increasing the display window width from 2000 to 2500 reduced the average observer performance by ~6%. Our principal finding is that radiographic technique factors have little effect on detection performance for lesions larger than ~0.8 mm, but that the visibility of smaller lesions is affected by quantum mottle in qualitative agreement with the predictions of the Rose model.

  12. Personality Traits Affect Teaching Performance of Attending Physicians: Results of a Multi-Center Observational Study

    PubMed Central

    Scheepers, Renée A.; Lombarts, Kiki M. J. M. H.; van Aken, Marcel A. G.; Heineman, Maas Jan; Arah, Onyebuchi A.

    2014-01-01

    Background Worldwide, attending physicians train residents to become competent providers of patient care. To assess adequate training, attending physicians are increasingly evaluated on their teaching performance. Research suggests that personality traits affect teaching performance, consistent with studied effects of personality traits on job performance and academic performance in medicine. However, up till date, research in clinical teaching practice did not use quantitative methods and did not account for specialty differences. We empirically studied the relationship of attending physicians' personality traits with their teaching performance across surgical and non-surgical specialties. Method We conducted a survey across surgical and non-surgical specialties in eighteen medical centers in the Netherlands. Residents evaluated attending physicians' overall teaching performance, as well as the specific domains learning climate, professional attitude, communication, evaluation, and feedback, using the validated 21-item System for Evaluation of Teaching Qualities (SETQ). Attending physicians self-evaluated their personality traits on a 5-point scale using the validated 10-item Big Five Inventory (BFI), yielding the Five Factor model: extraversion, conscientiousness, neuroticism, agreeableness and openness. Results Overall, 622 (77%) attending physicians and 549 (68%) residents participated. Extraversion positively related to overall teaching performance (regression coefficient, B: 0.05, 95% CI: 0.01 to 0.10, P = 0.02). Openness was negatively associated with scores on feedback for surgical specialties only (B: −0.10, 95% CI: −0.15 to −0.05, P<0.001) and conscientiousness was positively related to evaluation of residents for non-surgical specialties only (B: 0.13, 95% CI: 0.03 to 0.22, p = 0.01). Conclusions Extraverted attending physicians were consistently evaluated as better supervisors. Surgical attending physicians who display high levels of

  13. OPERATIONAL AND COMPOSITIONAL FACTORS THAT AFFECT THE PERFORMANCE PROPERTIES OF ARP/MCU SALTSTONE GROUT

    SciTech Connect

    Reigel, M.; Edwards, T.; Pickenheim, B.

    2012-02-15

    that of the sample cured at room temperature. The hydration reactions initiated during the mixing of the premix and salt solution continue during the curing period in the vaults to produce the hardened waste form product. The heat generated from exothermic hydration reactions results in a temperature increase in the vaults that depends on the composition of the decontaminated salt solution being dispositioned, the grout formulation (mix design) and the pour frequency and volume. This heat generation is a contributing factor to the temperature increase in the vaults that leads to an increased cure temperature for the grout. This report will further investigate the impact of curing temperature on saltstone performance properties (hydraulic conductivity, Young's modulus, porosity, etc.) over a range of aluminate concentration, water to premix (w/p) ratio and weight percent fly ash in the premix processed at the SPF. The three curing temperatures selected for this study were chosen to provide data at fixed cure temperatures that represent measured temperatures in the SDF vaults. This does not represent the conditions in the vault where the temperature of the saltstone is continually changing with time. For example, it may take several days for the saltstone to reach 60 C at a given elevation. Previous results demonstrated that the rates at which a selected curing temperature is reached affect the performance properties. The approach taken in this task, a rapid increase to the curing temperature, may be conservative with respect to decreased performance. Nevertheless, the data will provide a basis from which to determine the impact of curing temperature on saltstone performance as a function of key variables. A statistical evaluation of the results for these mixes will be performed to provide the range, and associated uncertainties, of hydraulic conductivity and other properties over this factor space.

  14. Intra-day signal instabilities affect decoding performance in an intracortical neural interface system

    NASA Astrophysics Data System (ADS)

    Perge, János A.; Homer, Mark L.; Malik, Wasim Q.; Cash, Sydney; Eskandar, Emad; Friehs, Gerhard; Donoghue, John P.; Hochberg, Leigh R.

    2013-06-01

    Objective. Motor neural interface systems (NIS) aim to convert neural signals into motor prosthetic or assistive device control, allowing people with paralysis to regain movement or control over their immediate environment. Effector or prosthetic control can degrade if the relationship between recorded neural signals and intended motor behavior changes. Therefore, characterizing both biological and technological sources of signal variability is important for a reliable NIS. Approach. To address the frequency and causes of neural signal variability in a spike-based NIS, we analyzed within-day fluctuations in spiking activity and action potential amplitude recorded with silicon microelectrode arrays implanted in the motor cortex of three people with tetraplegia (BrainGate pilot clinical trial, IDE). Main results. 84% of the recorded units showed a statistically significant change in apparent firing rate (3.8 ± 8.71 Hz or 49% of the mean rate) across several-minute epochs of tasks performed on a single session, and 74% of the units showed a significant change in spike amplitude (3.7 ± 6.5 µV or 5.5% of mean spike amplitude). 40% of the recording sessions showed a significant correlation in the occurrence of amplitude changes across electrodes, suggesting array micro-movement. Despite the relatively frequent amplitude changes, only 15% of the observed within-day rate changes originated from recording artifacts such as spike amplitude change or electrical noise, while 85% of the rate changes most likely emerged from physiological mechanisms. Computer simulations confirmed that systematic rate changes of individual neurons could produce a directional ‘bias’ in the decoded neural cursor movements. Instability in apparent neuronal spike rates indeed yielded a directional bias in 56% of all performance assessments in participant cursor control (n = 2 participants, 108 and 20 assessments over two years), resulting in suboptimal performance in these sessions

  15. RF communication with implantable wireless device: effects of beating heart on performance of miniature antenna

    PubMed Central

    Borghi, Alessandro; Bahmanyar, Mohammad Reza; McLeod, Christopher N.; Navaratnarajah, Manoraj; Yacoub, Magdi; Toumazou, Christofer

    2014-01-01

    The frequency response of an implantable antenna is key to the performance of a wireless implantable sensor. If the antenna detunes significantly, there are substantial power losses resulting in loss of accuracy. One reason for detuning is because of a change in the surrounding environment of an antenna. The pulsating anatomy of the human heart constitutes such a changing environment, so detuning is expected but this has not been quantified dynamically before. Four miniature implantable antennas are presented (two different geometries) along with which are placed within the heart of living swine the dynamic reflection coefficients. These antennas are designed to operate in the short range devices frequency band (863–870 MHz) and are compatible with a deeply implanted cardiovascular pressure sensor. The measurements recorded over 27 seconds capture the effects of the beating heart on the frequency tuning of the implantable antennas. When looked at in the time domain, these effects are clearly physiological and a combination of numerical study and posthumous autopsy proves this to be the case, while retrospective simulation confirms this hypothesis. The impact of pulsating anatomy on antenna design and the need for wideband implantable antennas is highlighted. PMID:26609377

  16. Performance characteristics and clinical evaluation of an in vitro bleeding time device--Thrombostat 4000.

    PubMed

    Alshameeri, R S; Mammen, E F

    1995-08-01

    The performance characteristics of an in vitro bleeding time device--Thrombostat 4000 were evaluated and compared with the Simplate bleeding time in healthy individuals and patients with disorders of primary hemostasis. Reference ranges were established using 30 normal volunteers. Although there were variations between different filter batches, reproducibility was good within a single batch. There were no differences between the two channels of the instrument and between male and female subjects. Hematocrit correlated negatively with the initial flow (IF) and IF correlated positively with closure time (T) and bleeding volume (V). Aspirin could be detected only when the traditional addition of ADP was replaced with CaCl2. Both, closure time (T) or bleeding volume (V) were more sensitive than Simplate bleeding time and T was more sensitive than V in detecting patients with disorders of primary hemostasis. We conclude that the Thrombostat 4000 is a reproducible, reliable, sensitive and easy to use instrument. It is superior to the traditional in vivo bleeding times for investigations of disorders of primary hemostasis (screening, diagnosis, monitoring, etc.). PMID:8533123

  17. High-performance computing-based exploration of flow control with micro devices.

    PubMed

    Fujii, Kozo

    2014-08-13

    The dielectric barrier discharge (DBD) plasma actuator that controls flow separation is one of the promising technologies to realize energy savings and noise reduction of fluid dynamic systems. However, the mechanism for controlling flow separation is not clearly defined, and this lack of knowledge prevents practical use of this technology. Therefore, large-scale computations for the study of the DBD plasma actuator have been conducted using the Japanese Petaflops supercomputer 'K' for three different Reynolds numbers. Numbers of new findings on the control of flow separation by the DBD plasma actuator have been obtained from the simulations, and some of them are presented in this study. Knowledge of suitable device parameters is also obtained. The DBD plasma actuator is clearly shown to be very effective for controlling flow separation at a Reynolds number of around 10(5), and several times larger lift-to-drag ratio can be achieved at higher angles of attack after stall. For higher Reynolds numbers, separated flow is partially controlled. Flow analysis shows key features towards better control. DBD plasma actuators are a promising technology, which could reduce fuel consumption and contribute to a green environment by achieving high aerodynamic performance. The knowledge described above can be obtained only with high-end computers such as the supercomputer 'K'. PMID:25024414

  18. High-performance computing-based exploration of flow control with micro devices

    PubMed Central

    Fujii, Kozo

    2014-01-01

    The dielectric barrier discharge (DBD) plasma actuator that controls flow separation is one of the promising technologies to realize energy savings and noise reduction of fluid dynamic systems. However, the mechanism for controlling flow separation is not clearly defined, and this lack of knowledge prevents practical use of this technology. Therefore, large-scale computations for the study of the DBD plasma actuator have been conducted using the Japanese Petaflops supercomputer ‘K’ for three different Reynolds numbers. Numbers of new findings on the control of flow separation by the DBD plasma actuator have been obtained from the simulations, and some of them are presented in this study. Knowledge of suitable device parameters is also obtained. The DBD plasma actuator is clearly shown to be very effective for controlling flow separation at a Reynolds number of around 105, and several times larger lift-to-drag ratio can be achieved at higher angles of attack after stall. For higher Reynolds numbers, separated flow is partially controlled. Flow analysis shows key features towards better control. DBD plasma actuators are a promising technology, which could reduce fuel consumption and contribute to a green environment by achieving high aerodynamic performance. The knowledge described above can be obtained only with high-end computers such as the supercomputer ‘K’. PMID:25024414

  19. Geometric Effect of Channel on Device Performance in Pentacene Thin-Film Transistor

    NASA Astrophysics Data System (ADS)

    Kang, Seong Jun; Noh, Myungkeun; Park, Dae Sik; Kim, Hui Jung; Kim, Sang Yeol; Koo, Bon Won; Kang, In Nam; Whang, Chung Nam

    2004-11-01

    We fabricated pentacene thin film-transistors on a glass substrate with a SiO2 layer via thermal evaporation in ultrahigh vacuum. We investigated the influence of channel length, channel width, and the deposition rate of a pentacene layer on organic thin film transistors (OTFTs) performance. Field-effect mobility of the transistors markedly increased as channel width decreased and channel length increased. The maximum drain current of OTFTs increased as channel length decreased. These observations indicate that the grain boundary scattering of charge carriers in the pentacene layer is a major hurdle in charge conduction, similarly to the observation in poly-Si TFTs. The maximum field-effect mobility was 0.69 cm2/Vs for a device prepared at 0.1 Å/s with a 50 μm channel length and a 20 μm channel width. Channel width/length ratio (W/L) as well as the deposition rate of the pentacene layer should be carefully chosen to increase field-effect mobility and maximum drain current in OTFTs.

  20. Novel Approach for Correlating Capacitance Data with Performance During Thin-Film Device Stress Studies: Preprint

    SciTech Connect

    Graham, R. L.; Albin, D. S.; Clark, L. A.

    2011-08-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and 1st and 2nd level performance metrics (efficiency, open-circuit voltage (VOC), short-circuit current density (JSC), and fill-factor (FF)) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between 1st and 2nd level metrics, 96.5% of the observed variation in efficiency was attributed to FF. The overall decrease in VOC after 1000 hours of open-circuit, light-soak stress at 60 degrees C was about 1.5%. As determined by our algorithm, the most consistent correlation existing between FF and 3rd level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  1. Free-Standing Conducting Polymer Films for High-Performance Energy Devices.

    PubMed

    Li, Zaifang; Ma, Guoqiang; Ge, Ru; Qin, Fei; Dong, Xinyun; Meng, Wei; Liu, Tiefeng; Tong, Jinhui; Jiang, Fangyuan; Zhou, Yifeng; Li, Ke; Min, Xue; Huo, Kaifu; Zhou, Yinhua

    2016-01-18

    Thick, uniform, easily processed, highly conductive polymer films are desirable as electrodes for solar cells as well as polymer capacitors. Here, a novel scalable strategy is developed to prepare highly conductive thick poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (HCT-PEDOT:PSS) films with layered structure that display a conductivity of 1400 S cm(-1) and a low sheet resistance of 0.59 ohm sq(-1). Organic solar cells with laminated HCT-PEDOT:PSS exhibit a performance comparable to the reference devices with vacuum-deposited Ag top electrodes. More importantly, the HCT-PEDOT:PSS film delivers a specific capacitance of 120 F g(-1) at a current density of 0.4 A g(-1). All-solid-state flexible symmetric supercapacitors with the HCT-PEDOT:PSS films display a high volumetric energy density of 6.80 mWh cm(-3) at a power density of 100 mW cm(-3) and 3.15 mWh cm(-3) at a very high power density of 16160 mW cm(-3) that outperforms previous reported solid-state supercapacitors based on PEDOT materials. PMID:26630234

  2. Advanced Aerodynamic Devices to Improve the Performance, Economics, Handling, and Safety of Heavy Vehicles

    SciTech Connect

    Robert J. Englar

    2001-05-14

    Research is being conducted at the Georgia Tech Research Institute (GTRI) to develop advanced aerodynamic devices to improve the performance, economics, stability, handling and safety of operation of Heavy Vehicles by using previously-developed and flight-tested pneumatic (blown) aircraft technology. Recent wind-tunnel investigations of a generic Heavy Vehicle model with blowing slots on both the leading and trailing edges of the trailer have been conducted under contract to the DOE Office of Heavy Vehicle Technologies. These experimental results show overall aerodynamic drag reductions on the Pneumatic Heavy Vehicle of 50% using only 1 psig blowing pressure in the plenums, and over 80% drag reductions if additional blowing air were available. Additionally, an increase in drag force for braking was confirmed by blowing different slots. Lift coefficient was increased for rolling resistance reduction by blowing only the top slot, while downforce was produced for traction increase by blowing only the bottom. Also, side force and yawing moment were generated on either side of the vehicle, and directional stability was restored by blowing the appropriate side slot. These experimental results and the predicted full-scale payoffs are presented in this paper, as is a discussion of additional applications to conventional commercial autos, buses, motor homes, and Sport Utility Vehicles.

  3. Performance study of microfluidic devices for blood plasma separation—a designer’s perspective

    NASA Astrophysics Data System (ADS)

    Tripathi, Siddhartha; Bala Varun Kumar, Y. V.; Prabhakar, Amit; Joshi, Suhas S.; Agrawal, Amit

    2015-08-01

    In this work, design and experiments on various blood plasma microdevices based on hydrodynamic flow separation techniques is carried out. We study their performance as a function of dependent governing parameters such as flow rate, feed hematocrit, and microchannel geometry. This work focuses on understanding separation phenomena in simple geometries; subsequently, individual simple geometrical parameters and biophysical effects are combined to fabricate hybridized designs, resulting in higher separation efficiencies. The distinctive features of our microfluidic devices are that they employ elevated dimensions (of the order of hundreds of microns), and thereby can be operated continuously over sufficient duration without clogging, while simplicity of fabrication makes them cost effective. The microdevices have been experimentally demonstrated over the entire range of hematocrit (i.e. from Hct 7% to Hct 45%). A high separation efficiency of about (78.34  ±  2.7)% with pure blood is achieved in our best hybrid design. We believe that the theory and experimental results presented in this study will aid designers and researchers working in the field of blood plasma separation microdevices.

  4. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device

    PubMed Central

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-01-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46 mWh·cm−3, a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°–180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices. PMID:25705048

  5. Interaction of Formulation and Device Factors Determine the In Vitro Performance of Salbutamol Sulphate Dry Powders for Inhalation.

    PubMed

    Muddle, Joanna; Murnane, Darragh; Parisini, Irene; Brown, Marc; Page, Clive; Forbes, Ben

    2015-11-01

    A variety of capsule-based dry powder inhalers were used to evaluate formulation-device interaction. The in vitro deposition of salbutamol sulphate (SS) was compared directly to published data for salmeterol xinafoate (SX). A 3(2) factorial design was used to assess the effect of SS formulations with three blends of different grade coarse lactose supplemented with different levels of fine lactose. These formulations were tested for homogeneity and evaluated for their in vitro deposition using Aeroliser, Handihaler and Rotahaler devices. The performance of the SS-lactose formulations differed across the grade of lactose and amount of fine lactose used compared to the same powder compositions blended with SX. SX had a greater fine particle fraction than SS for most of the comparable formulations, probably because of the different cohesiveness of the drugs. A head-to-head comparison of 'matched' SX and SS formulations when aerosolised from the same three devices demonstrated that formulation-device interactions are as critical in determining the in vitro deposition of drug-lactose blends as the identity of the active pharmaceutical ingredient. This work has revealed the limitations of the interpretative value of published in vitro performance data generated with a single device (even at equivalent aerosolisation force), when designing formulations for a different device. PMID:26220184

  6. Room temperature synthesis of cobalt-manganese-nickel oxalates micropolyhedrons for high-performance flexible electrochemical energy storage device

    NASA Astrophysics Data System (ADS)

    Zhang, Yi-Zhou; Zhao, Junhong; Xia, Jing; Wang, Lulu; Lai, Wen-Yong; Pang, Huan; Huang, Wei

    2015-02-01

    Cobalt-manganese-nickel oxalates micropolyhedrons were successfully fabricated by a room temperature chemical co-precipitation method. Interestingly, the Co0.5Mn0.4Ni0.1C2O4*nH2O micropolyhedrons and graphene nanosheets have been successfully applied as the positive and negative electrode materials (a battery type Faradaic electrode and a capacitive electrode, respectively) for flexible solid-state asymmetric supercapacitors. More importantly, the as-assembled device achieved a maximum energy density of 0.46 mWh.cm-3, a decent result among devices with similar structures. The as-assembled device showed good flexibility, functioning well under both normal and bent conditions (0°-180°). The resulting device showed little performance decay even after 6000 cycles, which rendered the Co0.5Mn0.4Ni0.1C2O4*nH2O//Graphene device configuration a promising candidate for high-performance flexible solid-state asymmetric supercapacitors in the field of high-energy-density energy storage devices.

  7. Is performance of intermittent intense exercise enhanced by use of a commercial palm cooling device?

    PubMed

    Walker, Thomas B; Zupan, Michael F; McGregor, Julia N; Cantwell, Andrew R; Norris, Torrance D

    2009-12-01

    The purpose of this study was to determine if using the CoreControl Rapid Thermal Exchange (RTX), a commercial palm cooling device, during active rest periods of multiple set training is an effective means to increase performance. Ten volunteers (5 men, 5 women) completed a VO2max test on a motorized treadmill and 3 interval running tests on a human powered treadmill. This treadmill allowed the subjects to quickly reach their running speed while allowing for measurement of distance, speed, and force. During the interval running tests the subjects completed eight 30-second intervals at a hard/fast pace followed by a 90-second walking or light jogging recovery period. During the recovery period, the subjects placed their left hand on 1 of 3 media: the RTX held at 15 degrees C (R), a 15 degrees C standard refrigerant gel pack (P), or nothing at all (C). Although there were differences in core temperature (Tc), subjective heat stress ratings, distance, and power generated between intervals, there were no significant differences (p < 0.05) found between treatments for any of these variables, nor was the interaction effect of interval*treatment found to be significant. Mean distance completed per trial was 717.1 m +/- 124.4 m (R), 724.8 m +/- 130.3 m (P), and 728.6 m +/- 110.6 m (C). Change in Tc from baseline to end-test averaged 1.41 degrees C +/- 0.37 degrees C (R), 1.41 degrees C +/- 0.39 degrees C (P), and 1.41 degrees C +/- 0.59 degrees C (C). There were no significant differences (p < 0.05) in Tc, heart rate (HR), or VO2 between intervals or treatments. We conclude that the RTX, in its current iteration, is ineffective at improving performance and/or mitigating thermal stress during high-intensity intermittent exercise. PMID:19910808

  8. A robotic device with a passive undulating ribbon fin: kinematics and propulsive performance

    NASA Astrophysics Data System (ADS)

    Liu, Hanlin; Curet, Oscar

    2015-11-01

    Many aquatic animals swim with high maneuverability using undulating ribbon fins. In this type of swimming, the organism propels by sending one or multiple traveling waves along an elongated fin. In previous work, robotic models with fully actuated fins where the parameters of the traveling waves are fully prescribed have been used to study the propulsive performance and fluid dynamics of this type of propulsion. However, less work has been done in ribbon fins with passively undulating waves. In this work, we use a robotic device to study the kinematics and propulsive performance of a passively undulating ribbon fin. The physical model is composed of fifteen rays interconnected with a membrane. Only two rays are actuated while the other rays are free to rotate through a common axis. The robotic fin was tested in a flume at different flow conditions. In a series of experiments we measured fin kinematics, propulsive forces and power consumption. As the leading two rays are actuated, a traveling wave with decaying amplitude passes through the passive rays. As the frequency of the actuated rays increases, the enclosed area of the undulating wave and the traveling wave frequency increase while the wavelength decreases. Our data also show that the propulsive force generated by the fin scaled with the enclosed area and the square of the relative velocity between incoming flow and traveling wave. These results suggest that both natural swimmers and underwater vehicles using ribbon-fin-based propulsion can potentially take advantage of passive undulating waves. National Science Foundation Grant No. 1420774

  9. Performances of Different Global Positioning System Devices for Time-Location Tracking in Air Pollution Epidemiological Studies

    PubMed Central

    Wu, Jun; Jiang, Chengsheng; Liu, Zhen; Houston, Douglas; Jaimes, Guillermo; McConnell, Rob

    2010-01-01

    Background: People’s time-location patterns are important in air pollution exposure assessment because pollution levels may vary considerably by location. A growing number of studies are using global positioning systems (GPS) to track people’s time-location patterns. Many portable GPS units that archive location are commercially available at a cost that makes their use feasible for epidemiological studies. Methods: We evaluated the performance of five portable GPS data loggers and two GPS cell phones by examining positional accuracy in typical locations (indoor, outdoor, in-vehicle) and factors that influence satellite reception (building material, building type), acquisition time (cold and warm start), battery life, and adequacy of memory for data storage. We examined stationary locations (eg, indoor, outdoor) and mobile environments (eg, walking, traveling by vehicle or bus) and compared GPS locations to highly-resolved US Geological Survey (USGS) and Digital Orthophoto Quarter Quadrangle (DOQQ) maps. Results: The battery life of our tested instruments ranged from <9 hours to 48 hours. The acquisition of location time after startup ranged from a few seconds to >20 minutes and varied significantly by building structure type and by cold or warm start. No GPS device was found to have consistently superior performance with regard to spatial accuracy and signal loss. At fixed outdoor locations, 65%–95% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices. At fixed indoor locations, 50%–80% of GPS points fell within 20-m of the corresponding DOQQ locations for all the devices except one. Most of the GPS devices performed well during commuting on a freeway, with >80% of points within 10-m of the DOQQ route, but the performance was significantly impacted by surrounding structures on surface streets in highly urbanized areas. Conclusions: All the tested GPS devices had limitations, but we identified several devices which showed

  10. Electroosmotic pump performance is affected by concentration polarizations of both electrodes and pump

    PubMed Central

    Suss, Matthew E.; Mani, Ali; Zangle, Thomas A.; Santiago, Juan G.

    2010-01-01

    Current methods of optimizing electroosmotic (EO) pump performance include reducing pore diameter and reducing ionic strength of the pumped electrolyte. However, these approaches each increase the fraction of total ionic current carried by diffuse electric double layer (EDL) counterions. When this fraction becomes significant, concentration polarization (CP) effects become important, and traditional EO pump models are no longer valid. We here report on the first simultaneous concentration field measurements, pH visualizations, flow rate, and voltage measurements on such systems. Together, these measurements elucidate key parameters affecting EO pump performance in the CP dominated regime. Concentration field visualizations show propagating CP enrichment and depletion fronts sourced by our pump substrate and traveling at order mm/min velocities through millimeter-scale channels connected serially to our pump. The observed propagation in millimeter-scale channels is not explained by current propagating CP models. Additionally, visualizations show that CP fronts are sourced by and propagate from the electrodes of our system, and then interact with the EO pump-generated CP zones. With pH visualizations, we directly detect that electrolyte properties vary sharply across the anode enrichment front interface. Our observations lead us to hypothesize possible mechanisms for the propagation of both pump- and electrode-sourced CP zones. Lastly, our experiments show the dynamics associated with the interaction of electrode and membrane CP fronts, and we describe the effect of these phenomena on EO pump flow rates and applied voltages under galvanostatic conditions. PMID:21516230

  11. Factors affecting the stability and performance of ipratropium bromide; fenoterol hydrobromide pressurized-metered dose inhalers.

    PubMed

    Ninbovorl, Jenjira; Sawatdee, Somchai; Srichana, Teerapol

    2013-12-01

    The aim of the study was to investigate the factors affecting the stability and performance of ipratropium bromide and fenoterol hydrobromide in a pressurized-metered dose inhaler (pMDI). A factorial design was applied to investigate the effects of three parameters (propellant, water, and ethanol) on the performance of 27 designed formulations of a solution-based pMDI. The formulations that contained a hydrofluoroalkane (HFA) propellant lower than 72% v/v and an ethanol concentration higher than 27% v/v remained as clear solutions. Nine formulations that contained the HFA propellant higher than 74% v/v precipitated. The results indicated that it was not only the HFA propellant content of the formulations that was related to the formulation instability but also ethanol content. Only six formulations from the 18 formulations, that did not precipitate, produced drug contents that were within the acceptable range (80-120%). These six formulations generated aerosols with mass median aerodynamic diameters (MMAD) of approximately 2 μm with a fine particle fraction (FPF; particle size, <6.4 μm) between 45% and 52%. The MMAD and FPF did not change significantly after 6 months of storage (P > 0.05). PMID:23975571

  12. Computer-Detected Attention Affects Foreign Language Listening but Not Reading Performance.

    PubMed

    Lee, Shu-Ping

    2016-08-01

    No quantitative study has explored the influence of attention on learning English as a foreign language (EFL). This study investigated whether computer-detected attention is associated with EFL reading and listening and reading and listening anxiety. Traditional paper-based English tests used as entrance examinations and tests of general trait anxiety, reading, listening, reading test state anxiety, and listening test state anxiety were administered in 252 Taiwan EFL college students who were divided into High Attention (Conners' Continuous Performance Test, CPT < 50) and Low Attention (CPT ≥ 50) groups. No differences were found between the two groups for traditional paper-based English tests, trait anxieties, general English reading anxiety scales, and general English listening anxiety scales. The Low Attention group had higher test state anxiety and lower listening test scores than the High Attention group, but not in reading. State anxiety during listening tests for EFL students with computer-detected low attention tendency was elevated and their EFL listening performance was affected, but those differences were not found in reading. PMID:27371638

  13. Factors affecting numerical typing performance of young adults in a hear-and-type task.

    PubMed

    Lin, Cheng-Jhe; Wu, Changxu

    2011-12-01

    Numerical hear-and-type tasks, i.e. making immediate keypresses according to verbally presented numbers, possess both practical and theoretical importance but received relatively little attention. Effects of speech rates (500-ms vs. 1000-ms interval), urgency (urgent condition: performance-based monetary incentive plus time limit vs. non-urgent condition: flat-rate compensation) and finger strategies (single vs. multi-finger typing) on typing speed and accuracy were investigated. Fast speech rate and multi-finger typing produced more errors and slower typing speed. Urgency improved typing speed but decreased accuracy. Errors were almost doubled under urgent condition, while urgency effect on speed was similar to that of speech rate. Examination of error patterns did not fully support Salthouse's (1986) speculations about error-making mechanisms. The results implied that urgency could play a more important role in error-making than task demands. Numerical keyboard design and error detection could benefit from spatial incidence of errors found in this study. STATEMENT OF RELEVANCE: This study revealed that classic speculations about error-making mechanisms in alphabetical typing do not necessarily translate to numerical typing. Factors other than external task demands such as urgency can affect typing performance to a similar or greater extent. Investigations of intrinsic error-making factors in non-traditional typing tasks are encouraged. PMID:22103724

  14. Germanium-on-Silicon Strain Engineered Materials for Improved Device Performance Grown by Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Bharathan, Jayesh Moorkoth

    present during epitaxy. The microstructural characteristics of Ge films were analyzed by x-ray diffraction, atomic force microscopy and transmission electron microscopy. The principal defects in the epitaxial films were determined to be threading dislocations and stacking faults. A unique defect appearing as a line during defect delineation was established to be a wide stacking fault arising from oxygen contamination during RPCVD epitaxy. A decrease in defect density by almost an order of magnitude was observed with increasing film thickness. Germanium films with a thickness of 3.5 mum exhibited the lowest threading dislocation densities of 5 x 106 cm-2. The mechanisms of interactions between threading dislocations has been discussed with the aid of transmission electron microscopy to explain the reduction in the observed threading dislocation density. A strong correlation was obtained between electrical performance of the devices and defect density. Thicker films with the lowest threading dislocation density of 5 x 106 cm-2 also yielded devices with the lowest dark current density of ˜ 5 mA/cm2 (1 V reverse bias) and bulk resistivity of 30 O cm2. All devices showed spectral response of up to 1.61 mum, confirming a strain-induced shrinkage of the direct band gap by approximately 30 meV, which is in good agreement with theoretical models. In summary, the structural, electrical, and optical properties of 2-D Ge films grown on Si(001) substrates by RPCVD has been investigated.

  15. Factors affecting the performance of community health workers in India: a multi-stakeholder perspective

    PubMed Central

    Sharma, Reetu; Webster, Premila; Bhattacharyya, Sanghita

    2014-01-01

    Background Community health workers (CHWs) form a vital link between the community and the health department in several countries. In India, since 2005 this role is largely being played by Accredited Social Health Activists (ASHAs), who are village-level female workers. Though ASHAs primarily work for the health department, in a model being tested in Rajasthan they support two government departments. Focusing on the ASHA in this new role as a link worker between two departments, this paper examines factors associated with her work performance from a multi-stakeholder perspective. Design The study was done in 16 villages from two administrative blocks of Udaipur district in Rajasthan. The findings are based on 63 in-depth interviews with ASHAs, their co-workers and representatives from the two departments. The interviews were conducted using interview guides. An inductive approach with open coding was used for manual data analysis. Results This study shows that an ASHA's motivation and performance are affected by a variety of factors that emerge from the complex context in which she works. These include various personal (e.g. education), professional (e.g. training, job security), and organisational (e.g. infrastructure) factors along with others that emerge from external work environment. The participants suggested various ways to address these challenges. Conclusion In order to improve the performance of ASHAs, apart from taking corrective actions at the professional and organisational front on a priority basis, it is equally essential to promote cordial work relationships amongst ASHAs and other community-level workers from the two departments. This will also have a positive impact on community health. PMID:25319596

  16. How does performance of ultrasound tissue typing affect design of prostate IMRT dose-painting protocols?

    SciTech Connect

    Zhang Pengpeng . E-mail: pz2010@columbia.edu; Osterman, K. Sunshine; Liu Tian; Li Xiang; Kessel, Jack; Wu, Leester; Schiff, Peter; Kutcher, Gerald J.

    2007-02-01

    Purpose: To investigate how the performance characteristics of ultrasound tissue typing (UTT) affect the design of a population-based prostate dose-painting protocol. Methods and Materials: The performance of UTT is evaluated using the receiver operating characteristic curve. As the imager's sensitivity increases, more tumors are detected, but the specificity worsens, causing more false-positive results. The UTT tumor map, obtained with a specific sensitivity and specificity setup, was used with the patient's CT image to guide intensity-modulated radiotherapy (IMRT) planning. The optimal escalation dose to the UTT positive region, as well as the safe dose to the negative background, was obtained by maximizing the uncomplicated control (i.e., a combination of tumor control probability and weighted normal tissue complication probability). For high- and low-risk tumors, IMRT plans guided by conventional ultrasound or UTT with a one-dimensional or two-dimensional spectrum analysis technique were compared with an IMRT plan in which the whole prostate was dose escalated. Results: For all imaging modalities, the specificity of 0.9 was chosen to reduce complications resulting from high false-positive results. If the primary tumors were low risk, the IMRT plans guided by all imaging modalities achieved high tumor control probability and reduced the normal tissue complication probability significantly compared with the plan with whole gland dose escalation. However, if the primary tumors were high risk, the accuracy of the imaging modality was critical to maintain the tumor control probability and normal tissue complication probability at acceptable levels. Conclusion: The performance characteristics of an imager have important implications in dose painting and should be considered in the design of dose-painting protocols.

  17. Low-temperature phase transitions in a soluble oligoacene and their effect on device performance and stability

    SciTech Connect

    Ward, J. W.; Goetz, K. P.; Obaid, A.; Diemer, P. J.; Jurchescu, O. D.; Payne, M. M.; Anthony, J. E.; Day, C. S.

    2014-08-25

    The use of organic semiconductors in high-performance organic field-effect transistors requires a thorough understanding of the effects that processing conditions, thermal, and bias-stress history have on device operation. Here, we evaluate the temperature dependence of the electrical properties of transistors fabricated with 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, a material that has attracted much attention recently due to its exceptional electrical properties. We have discovered a phase transition at T = 205 K and discuss its implications on device performance and stability. We examined the impact of this low-temperature phase transition on the thermodynamic, electrical, and structural properties of both single crystals and thin films of this material. Our results show that while the changes to the crystal structure are reversible, the induced thermal stress yields irreversible degradation of the devices.

  18. Low-temperature phase transitions in a soluble oligoacene and their effect on device performance and stability

    NASA Astrophysics Data System (ADS)

    Ward, J. W.; Goetz, K. P.; Obaid, A.; Payne, M. M.; Diemer, P. J.; Day, C. S.; Anthony, J. E.; Jurchescu, O. D.

    2014-08-01

    The use of organic semiconductors in high-performance organic field-effect transistors requires a thorough understanding of the effects that processing conditions, thermal, and bias-stress history have on device operation. Here, we evaluate the temperature dependence of the electrical properties of transistors fabricated with 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, a material that has attracted much attention recently due to its exceptional electrical properties. We have discovered a phase transition at T = 205 K and discuss its implications on device performance and stability. We examined the impact of this low-temperature phase transition on the thermodynamic, electrical, and structural properties of both single crystals and thin films of this material. Our results show that while the changes to the crystal structure are reversible, the induced thermal stress yields irreversible degradation of the devices.

  19. Subsonic Maneuvering Effectiveness of High Performance Aircraft Which Employ Quasi-Static Shape Change Devices

    NASA Technical Reports Server (NTRS)

    Montgomery, Raymond C.; Scott, Michael A.; Weston, Robert P.

    1998-01-01

    This paper represents an initial study on the use of quasi-static shape change devices in aircraft maneuvering. The macroscopic effects and requirements for these devices in flight control are the focus of this study. Groups of devices are postulated to replace the conventional leading-edge flap (LEF) and the all-moving wing tip (AMT) on the tailless LMTAS-ICE (Lockheed Martin Tactical Aircraft Systems - Innovative Control Effectors) configuration. The maximum quasi-static shape changes are 13.8% and 7.7% of the wing section thickness for the LEF and AMT replacement devices, respectively. A Computational Fluid Dynamics (CFD) panel code is used to determine the control effectiveness of groups of these devices. A preliminary design of a wings-leveler autopilot is presented. Initial evaluation at 0.6 Mach at 15,000 ft. altitude is made through batch simulation. Results show small disturbance stability is achieved, however, an increase in maximum distortion is needed to statically offset five degrees of sideslip. This only applies to the specific device groups studied, encouraging future research on optimal device placement.

  20. Investigation of thioglycerol stabilized ZnS quantum dots in electroluminescent device performance

    NASA Astrophysics Data System (ADS)

    Ethiraj, Anita Sagadevan; Rhen, Dani; Lee, D. H.; Kang, Dae Joon; Kulkarni, S. K.

    2016-05-01

    The present work is focused on the investigation of thioglycerol (TG) stabilized Zinc Sulfide Quantum dots (ZnS QDs) in the hybrid electroluminescence (EL) device. Optical absorption spectroscopy clearly indicates the formation of narrow size distributed ZnS in the quantum confinement regime. X-ray Diffraction (XRD), Photoluminescence (PL), Energy Dispersive X-ray Spectroscopy (EDS) data supports the same. The hybrid EL device with structure of ITO (indium tin oxide)//PEDOT:PSS ((poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)//HTL (α NPD- N,N'-diphenyl-N,N'-bis(1-naphthyl)-(1,1'-phenyl)-4,4'-diamine// PVK:ZnS QDs//ETL(PBD- 2-tert-butylphenyl- 5-biphenyl-1,3,4-oxadiazole)//LiF:Al (Device 1) was fabricated. Reference device without the ZnS QDs were also prepared (Device 2). The results show that the ZnS QDs based device exhibited bright electroluminescence emission of 24 cd/m2 at a driving voltage of 16 Volts under the forward bias conditions as compared to the reference device without the ZnS QDs, which showed 6 cd/m2 at ˜22 Volts.

  1. Design and performance of a respiratory amplitude gating device for PET/CT imaging

    SciTech Connect

    Chang Guoping; Chang Tingting; Clark, John W. Jr.; Mawlawi, Osama R.

    2010-04-15

    Purpose: Recently, the authors proposed a free-breathing amplitude gating (FBAG) technique for PET/CT scanners. The implementation of this technique required specialized hardware and software components that were specifically designed to interface with commercial respiratory gating devices to generate the necessary triggers required for the FBAG technique. The objective of this technical note is to introduce an in-house device that integrates all the necessary hardware and software components as well as tracks the patient's respiratory motion to realize amplitude gating on PET/CT scanners. Methods: The in-house device is composed of a piezoelectric transducer coupled to a data-acquisition system in order to monitor the respiratory waveform. A LABVIEW program was designed to control the data-acquisition device and inject triggers into the PET list stream whenever the detected respiratory amplitude crossed a predetermined amplitude range. A timer was also programmed to stop the scan when the accumulated time within the selected amplitude range reached a user-set interval. This device was tested using a volunteer and a phantom study. Results: The results from the volunteer and phantom studies showed that the in-house device can detect similar respiratory signals as commercially available respiratory gating systems and is able to generate the necessary triggers to suppress respiratory motion artifacts. Conclusions: The proposed in-house device can be used to implement the FBAG technique in current PET/CT scanners.

  2. Self-Evaluation Accuracy and Satisfaction with Performance: Are there Affective Costs or Benefits of Positive Self-Evaluation Bias?

    ERIC Educational Resources Information Center

    Narciss, Susanne; Koerndle, Hermann; Dresel, Markus

    2011-01-01

    This paper examines how self-evaluation biases may influence satisfaction with performance. A review of theoretical positions suggests there are two views, both of which are supported by studies involving laboratory tasks. The first view predicts affective costs, and the second affective benefits of positive self-evaluation bias. We test the…

  3. Exogenous lactate supply affects lactate kinetics of rainbow trout, not swimming performance

    PubMed Central

    Omlin, Teye; Langevin, Karolanne

    2014-01-01

    Intense swimming causes circulatory lactate accumulation in rainbow trout because lactate disposal (Rd) is not stimulated as strongly as lactate appearance (Ra). This mismatch suggests that maximal Rd is limited by tissue capacity to metabolize lactate. This study uses exogenous lactate to investigate what constrains maximal Rd and minimal Ra. Our goals were to determine how exogenous lactate affects: 1) Ra and Rd of lactate under baseline conditions or during graded swimming, and 2) exercise performance (critical swimming speed, Ucrit) and energetics (cost of transport, COT). Results show that exogenous lactate allows swimming trout to boost maximal Rd lactate by 40% and reach impressive rates of 56 μmol·kg−1·min−1. This shows that the metabolic capacity of tissues for lactate disposal is not responsible for setting the highest Rd normally observed after intense swimming. Baseline endogenous Ra (resting in normoxic water) is not significantly reduced by exogenous lactate supply. Therefore, trout have an obligatory need to produce lactate, either as a fuel for oxidative tissues and/or from organs relying on glycolysis. Exogenous lactate does not affect Ucrit or COT, probably because it acts as a substitute for glucose and lipids rather than extra fuel. We conclude that the observed 40% increase in Rd lactate is made possible by accelerating lactate entry into oxidative tissues via monocarboxylate transporters (MCTs). This observation together with the weak expression of MCTs and the phenomenon of white muscle lactate retention show that lactate metabolism of rainbow trout is significantly constrained by transmembrane transport. PMID:25121611

  4. Hemodynamic and affective correlates assessed during performance on the Columbia card task (CCT).

    PubMed

    Holper, Lisa; Murphy, Ryan O

    2014-12-01

    The study aimed to test the potential of functional near-infrared spectroscopy (fNIRS) in combination with electrodermal activity (EDA) in a decision paradigm by means of the Columbia card task (CCT). The CCT is a dynamic decision task characterized by assessing subjects' risk-taking via eliciting voluntary stopping points in a series of incrementally increasingly risky choices. Using the combined fNIRS-EDA approach, we aim to examine the hemodynamic and affective correlates of both decision and outcome responses during performance on the CCT. Twenty healthy subjects completed the Cold and Hot CCT version while fNIRS over prefrontal cortex and EDA were recorded. Results showed that (1) in the decision phase fNIRS revealed larger total hemoglobin concentration changes [tHb] in the Cold as compared to the Hot CCT, whereas EDA revealed an opposite pattern with larger skin conductance responses (SCRs) to the Hot as compared to the Cold CCT. (2) No significant [tHb] signals or SCRs were found in the outcome phase. (3) Coherence calculations between fNIRS and EDA in the heart rate frequency showed a significant increase during the Hot as compared to the Cold CCT. Our findings designate fNIRS as suitable tool for monitoring decision-making processes. The combination of fNIRS and EDA demonstrates the potential of simultaneously assessing the interaction between hemodynamic and affective responses which can provide additional information concerning the relationship between these two physiological systems for various research areas. PMID:24242358

  5. Affective Factors in the Mediation of Background Effects on Cognitive Performance.

    ERIC Educational Resources Information Center

    Cuttance, Peter F.

    1980-01-01

    Academic achievement at age 16 was influenced more by achievement at age 14 than by affective variables. Affective variables included academic and occupational aspiration, parent expectations, school attitudes, sex, socioeconomic status, parents' education, and migrancy. (CP)

  6. Development of Pneumatic Aerodynamic Devices to Improve the Performance, Economics, and Safety of Heavy Vehicles

    SciTech Connect

    Robert J. Englar

    2000-06-19

    Under contract to the DOE Office of Heavy Vehicle Technologies, the Georgia Tech Research Institute (GTRI) is developing and evaluating pneumatic (blown) aerodynamic devices to improve the performance, economics, stability and safety of operation of Heavy Vehicles. The objective of this program is to apply the pneumatic aerodynamic aircraft technology previously developed and flight-tested by GTRI personnel to the design of an efficient blown tractor-trailer configuration. Recent experimental results obtained by GTRI using blowing have shown drag reductions of 35% on a streamlined automobile wind-tunnel model. Also measured were lift or down-load increases of 100-150% and the ability to control aerodynamic moments about all 3 axes without any moving control surfaces. Similar drag reductions yielded by blowing on bluff afterbody trailers in current US trucking fleet operations are anticipated to reduce yearly fuel consumption by more than 1.2 billion gallons, while even further reduction is possible using pneumatic lift to reduce tire rolling resistance. Conversely, increased drag and down force generated instantaneously by blowing can greatly increase braking characteristics and control in wet/icy weather due to effective ''weight'' increases on the tires. Safety is also enhanced by controlling side loads and moments caused on these Heavy Vehicles by winds, gusts and other vehicles passing. This may also help to eliminate the jack-knifing problem if caused by extreme wind side loads on the trailer. Lastly, reduction of the turbulent wake behind the trailer can reduce splash and spray patterns and rough air being experienced by following vehicles. To be presented by GTRI in this paper will be results developed during the early portion of this effort, including a preliminary systems study, CFD prediction of the blown flowfields, and design of the baseline conventional tractor-trailer model and the pneumatic wind-tunnel model.

  7. High-Performance Electrochromic Devices Based on Poly[Ni(salen)]-Type Polymer Films.

    PubMed

    Nunes, Marta; Araújo, Mariana; Fonseca, Joana; Moura, Cosme; Hillman, Robert; Freire, Cristina

    2016-06-01

    We report the application of two poly[Ni(salen)]-type electroactive polymer films as new electrochromic materials. The two films, poly[Ni(3-Mesalen)] (poly[1]) and poly[Ni(3-MesaltMe)] (poly[2]), were successfully electrodeposited onto ITO/PET flexible substrates, and their voltammetric characterization revealed that poly[1] showed similar redox profiles in LiClO4/CH3CN and LiClO4/propylene carbonate (PC), while poly[2] showed solvent-dependent electrochemical responses. Both films showed multielectrochromic behavior, exhibiting yellow, green, and russet colors according to their oxidation state, and promising electrochromic properties with high electrochemical stability in LiClO4/PC supporting electrolyte. In particular, poly[1] exhibited a very good electrochemical stability, changing color between yellow and green (λ = 750 nm) during 9000 redox cycles, with a charge loss of 34.3%, an optical contrast of ΔT = 26.2%, and an optical density of ΔOD = 0.49, with a coloration efficiency of η = 75.55 cm(2) C(-1). On the other hand, poly[2] showed good optical contrast for the color change from green to russet (ΔT = 58.5%), although with moderate electrochemical stability. Finally, poly[1] was used to fabricate a solid-state electrochromic device using lateral configuration with two figures of merit: a simple shape (typology 1) and a butterfly shape (typology 2); typology 1 showed the best performance with optical contrast ΔT = 88.7% (at λ = 750 nm), coloration efficiency η = 130.4 cm(2) C(-1), and charge loss of 37.0% upon 3000 redox cycles. PMID:27175794

  8. Investigation on the performance of dedicated radiotherapy positioning devices for MR scanning for prostate planning.

    PubMed

    Sun, Jidi; Dowling, Jason A; Pichler, Peter; Parker, Joel; Martin, Jarad; Stanwell, Peter; Arm, Jameen; Menk, Fred; Greer, Peter B

    2015-01-01

    The purpose of this study was to investigate performance of the couch and coil mounts designed for MR-simulation prostate scanning using data from ten volunteers. Volunteers were scanned using the standard MR scanning protocol with the MR coil directly strapped on the external body and the volunteer lying on the original scanner table. They also were scanned using a MR-simulation table top and pelvic coil mounts. MR images from both setups were compared in terms of body contour variation and image quality effects within particular organs of interest. Six-field conformal plans were generated on the two images with assigned bulk density for dose calculation. With the MR-simulation devices, the anterior skin deformation was reduced by up to 1.7 cm. The hard tabletop minimizes the posterior body deformation which can be up to 2.3 cm on the standard table, depending on the weight of volunteer. The image signal-to-noise ratio reduced by 14% and 25% on large field of view (FOV) and small FOV images, respectively, after using the coil mount; the prostate volume contoured on two images showed difference of 1.05 ± 0.66 cm3. The external body deformation caused a mean dose reduction of 0.6 ± 0.3 Gy, while the coverage reduced by 22% ± 13% and 27% ± 6% in V98 and V100, respectively. A dedicated MR simulation setup for prostate radiotherapy is essential to ensure the agreement between planning anatomy and treatment anatomy. The image signal was reduced after applying the coil mount, but no significant effect was found on prostate contouring. PMID:26103166

  9. Adaptive cellular structures and devices with internal features for enhanced structural performance

    NASA Astrophysics Data System (ADS)

    Pontecorvo, Michael Eugene

    This dissertation aims to develop a family of cellular and repeatable devices that exhibit a variety of force-displacement behaviors. It is envisioned that these cellular structures might be used either as stand-alone elements, or combined and repeated to create multiple types of structures (i.e. buildings, ship hulls, vehicle subfloors, etc.) with the ability to passively or actively perform multiple functions (harmonic energy dissipation, impact mitigation, modulus change) over a range of loading types, amplitudes, and frequencies. To accomplish this goal, this work combines repeatable structural frameworks, such as that provided by a hexagonal cellular structure, with internal structural elements such as springs, viscous dampers, buckling plates, bi-stable von Mises trusses (VMTs), and pneumatic artificial muscles (PAMs). The repeatable framework serves to position damping and load carrying elements throughout the structure, and the configuration of the internal elements allow each cell to be tuned to exhibit a desired force-displacement response. Therefore, gradient structures or structures with variable load paths can be created for an optimal global response to a range of loads. This dissertation focuses on the development of cellular structures for three functions: combined load-carrying capability with harmonic energy dissipation, impact mitigation, and cell modulus variation. One or more conceptual designs are presented for devices that can perform each of these functions, and both experimental measurements and simulations are used to gain a fundamental understanding of each device. Chapter 2 begins with a presentation of a VMT model that is the basis for many of the elements. The equations of motion for the VMT are derived and the static and dynamic behavior of the VMT are discussed in detail. Next, two metrics for the energy dissipation of the VMT - hysteresis loop area and loss factor - are presented. The responses of the VMT to harmonic displacement

  10. Glass-to-metal bonding process improves stability and performance of semiconductor devices

    NASA Technical Reports Server (NTRS)

    Trent, R. L.

    1970-01-01

    Anodic bonding of glass coverslips to photodiodes and photovoltaic devices eliminates the need for adhesive. The process requires relatively low temperatures /less than 560 degrees C/ and the metals and glass remain solid throughout the bonding process.

  11. High-performance spinning device for DVD-based micromechanical signal transduction

    NASA Astrophysics Data System (ADS)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo G.; Wang, Wei-Min; Ko, Hsien-Chen; Hwang, Ing-Shouh; Boisen, Anja; Huang, Kuang-Yuh

    2013-04-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning mechanism, this device can simultaneously measure surface topography, mechanical deflections and resonance frequencies of several microfabricated beams at a high speed. In biochemical sensing applications, the OPU can measure bending changes of functionalized microcantilevers, providing a statistically robust and label-free bio-detection analysis of multiple compounds. The signal-to-noise ratio (S/N) is demonstrated from statistical measurements as 1.2 with arginine detection at 750 nM concentration. Practically, the OPU can measure up to 480 individual cantilever sensors per second with nanometer resolution. The opto-mechanical optimization of the device design and settings for biochemical detection are described.

  12. Negative differential resistance and rectifying performance induced by doped graphene nanoribbons p-n device

    NASA Astrophysics Data System (ADS)

    Zhou, Yuhong; Qiu, Nianxiang; Li, Runwei; Guo, Zhansheng; Zhang, Jian; Fang, Junfeng; Huang, Aisheng; He, Jian; Zha, Xianhu; Luo, Kan; Yin, Jingshuo; Li, Qiuwu; Bai, Xiaojing; Huang, Qing; Du, Shiyu

    2016-03-01

    Employing nonequilibrium Green's Functions in combination with density functional theory, the electronic transport properties of armchair graphene nanoribbon (GNR) devices with various widths are investigated in this work. In the adopted model, two semi-infinite graphene electrodes are periodically doped with boron or nitrogen atoms. Our calculations reveal that these devices have a striking nonlinear feature and show notable negative differential resistance (NDR). The results also indicate the diode-like properties are reserved and the rectification ratios are high. It is found the electronic transport properties are strongly dependent on the width of doped nanoribbons and the positions of dopants and three distinct families are elucidated for the current armchair GNR devices. The NDR as well as rectifying properties can be well explained by the variation of transmission spectra and the relative shift of discrete energy states with applied bias voltage. These findings suggest that the doped armchair GNR is a promising candidate for the next generation nanoscale device.

  13. An investigation of the performance of novel chorded keyboards in combination with pointing input devices.

    PubMed

    Shi, Wen-Zhou; Wu, Fong-Gong

    2015-01-01

    Rapid advances in computing power have driven the development of smaller and lighter technology products, with novel input devices constantly being produced in response to new user behaviors and usage contexts. The aim of this research was to investigate the feasibility of operating chorded keyboard control modules in concert with pointing devices such as styluses and mice. We compared combinations of two novel chorded keyboards with different pointing devices in hopes of finding a better combination for future electronic products. Twelve participants were recruited for simulation testing, and paired sample t testing was conducted to determine whether input and error rates for the novel keyboards were improved significantly over those of traditional input methods. The most efficient input device combination tested was the combination of a novel cross-shaped key keyboard and a stylus, suggesting the high potential for use of this combination with future mobile IT products. PMID:25064640

  14. Dynamic characterization and modelling of a dual-axis beam steering device for performance understanding, optimization and control design

    NASA Astrophysics Data System (ADS)

    Berglund, Martin; Palmer, Kristoffer; Lotfi, Sara; Kratz, Henrik; Thornell, Greger

    2013-04-01

    This paper presents a lumped thermal model of a dual-axis laser micromirror device for beam steering in a free-space optical (FSO) communication system, designed for fractionated spacecraft. An FSO communication system provides several advantages, such as larger bandwidth, smaller size and weight of the communication payload and less power consumption. A dual-axis mirror device is designed and realized using microelectromechanical systems technology. The fabrication is based on a double-sided, bulk micromachining process, where the mirror actuates thermally by joints consisting of v-grooves filled with the SU-8 polymer. The size of the device, consisting of a mirror, which is deflectable versus its frame in one direction, and through deflection of the frame in the other, is 15.4 × 10.4 × 0.3 mm3. In order to further characterize and understand the micromirror device, a Simulink state-space model of the actuator is set up using thermal and mechanical properties from a realized actuator. A deviation of less than 2% between the modelled and measured devices was obtained in an actuating temperature range of 20-200 °C. The model of the physical device was examined by evaluating its performance in vacuum, and by changing physical parameters, such as thickness and material composition. By this, design parameters were evaluated for performance gain and usability. For example, the crosstalk between the two actuators deflecting the mirror along its two axes in atmospheric pressure is projected to go down from 97% to 6% when changing the frame material from silicon to silicon dioxide. A feedback control system was also designed around the model in order to examine the possibility to make a robust control system for the physical device. In conclusion, the model of the actuator presented in this paper can be used for further understanding and development of the actuator system.

  15. In-situ characterization of electrochromism based on ITO/PEDOT:PSS towards preparation of high performance device

    NASA Astrophysics Data System (ADS)

    Xue-Jin, Wang; Zheng-Fei, Guo; Jing-Yu, Qu; Kun, Pan; Zheng, Qi; Li, Hong

    2016-02-01

    Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is usually sandwiched between indium tin oxide (ITO) and a functional polymer in order to improve the performance of the device. However, because of the strong acidic nature of PEDOT:PSS, the instability of ITO/PEDOT:PSS interface is also observed. The mechanism of degradation of the device remains is unclear and needs to be further studied. In this article, we investigate the in-situ electrochromism of PEDOT:PSS to disclose the cause of the degradation. X-ray photoelectron spectroscopy (XPS) was used to characterize the PEDOT:PSS films, as well as the PEDOT:PSS plus polyethylene glycol (PEG) films with and without indium ions. The electrochromic devices (ECD) based on PEDOT:PSS and PEG with and without indium ions are carried out by in-situ micro-Raman and laser reflective measurement (LRM). For comparison, ECD based on PEDOT:PSS and PEG films with LiCl, KCl, NaCl or InCl3 are also investigated by LRM. The results show that PEDOT:PSS is further reduced when negatively biased, and oxidized when positively biased. This could identify that PEDOT:PSS with indium ions from PEDOT:PSS etching ITO will lose dopants when negatively biased. The LRM shows that the device with indium ions has a stronger effect on the reduction property of PEDOT:PSS-PEG film than the device without indium ions. The contrast of the former device is 44%, that of the latter device is about 3%. The LRM also shows that the contrasts of the device based on PEDOT:PSS+PEG with LiCl, KCl, NaCl, InCl3 are 30%, 27%, 15%, and 18%, respectively. Project supported by the National High Technology Research and Development Program of China (Grant No. 2015AA034201) and the Chinese Universities Scientific Fund (Grant No. 2015LX002).

  16. Performance and scaling effects in a multilayer microfluidic extracorporeal lung oxygenation device

    PubMed Central

    Kniazeva, Tatiana; Epshteyn, Alla A.; Hsiao, James C.; Kim, Ernest S.; Kolachalama, Vijaya B.; Charest, Joseph L.

    2012-01-01

    Microfluidic fabrication technologies are emerging as viable platforms for extracorporeal lung assist devices and oxygenators for cardiac surgical support and critical care medicine, based in part on their ability to more closely mimic the architecture of the human vasculature than existing technologies. In comparison with current hollow fiber oxygenator technologies, microfluidic systems have more physiologically-representative blood flow paths, smaller cross section blood conduits and thinner gas transfer membranes. These features can enable smaller device sizes and a reduced blood volume in the oxygenator, enhanced gas transfer efficiencies, and may also reduce the tendency for clotting in the system. Several critical issues need to be addressed in order to advance this technology from its current state and implement it in an organ-scale device for clinical use. Here we report on the design, fabrication and characterization of multilayer microfluidic oxygenators, investigating scaling effects associated with fluid mechanical resistance, oxygen transfer efficiencies, and other parameters in multilayer devices. Important parameters such as the fluidic resistance of interconnects are shown to become more predominant as devices are scaled towards many layers, while other effects such as membrane distensibility become less significant. The present study also probes the relationship between blood channel depth and membrane thickness on oxygen transfer, as well as the rate of oxygen transfer on the number of layers in the device. These results contribute to our understanding of the complexity involved in designing three-dimensional microfluidic oxygenators for clinical applications. PMID:22418858

  17. Laying performance and egg quality of blue-shelled layers as affected by different housing systems.

    PubMed

    Wang, X L; Zheng, J X; Ning, Z H; Qu, L J; Xu, G Y; Yang, N

    2009-07-01

    Blue-shelled eggs are gaining popularity as the consumption demand diversifies in some countries. This study was carried out to investigate the laying performance and egg quality of the blue-shelled egg layers as well as the effects of different housing systems on egg production and quality traits. One thousand pullets from Dongxiang blue-shelled layers were divided into 2 even groups and kept in different housing systems (outdoor vs. cage). Daily laying performance was recorded from 20 to 60 wk of age. External and internal egg quality traits were examined at 26, 34, 42, and 50 wk. Yolk cholesterol concentration and whole egg cholesterol content were measured at 40 wk of age. Average laying rate from 20 to 60 wk for the cage (54.7%) was significantly higher than that of outdoor layers (39.3%). Among all of the egg quality traits, only eggshell color was affected by housing system. Interaction between housing system and layer age was found in egg weight, eggshell color, eggshell ratio, yolk color, and yolk weight. Meanwhile, cholesterol concentration in yolk was 8.64 +/- 0.40 mg/g in the outdoor eggs, which was significantly lower than that of eggs from the cage birds (10.32 +/- 0.48 mg/g; P < 0.05). Whole egg cholesterol content in the outdoor eggs (125.23 +/- 6.32 mg/egg) was also significantly lower than that of eggs from the caged layers (158.01 +/- 8.62 mg/egg). The results demonstrated that blue-shelled layers have lower productivity in the outdoor system than in the cage system. Blue-shelled layers have lower egg weight, larger yolk proportion, and lower cholesterol content compared with commercial layers. In a proper marketing system, lower productivity could be balanced by a higher price for the better quality of blue-shelled eggs. PMID:19531721

  18. Performing the Bakla in The Care Divas: Crossdressing, Affective Labor, and the Glimpse of the Cosmopolitan.

    PubMed

    Tiatco, Anril Pineda

    2015-01-01

    This essay is a close reading of The Care Divas, a Filipino musical revolving around the struggle of five Filipino caregivers in Israel who also struggle with their sexual identities as bakla (Filipino homosexual). The analysis is both an affirmation and a critique of the performance. In the affirmation, the musical is argued to present a social reality that is intended for and in need of interrogation: the Filipino bakla. The musical implicitly features the bakla as a cosmopolitan. At the outset, this cosmopolitan disposition comes from the fact that the characters are migrant workers (caregivers). But more importantly, the cosmopolitan character is from a responsibility toward the other anchored within a genuine caring as implicated in the affective labor of these caregiver characters. In the critique, the essay marks some problematic limitations in the treatment of the bakla. In doing so, the musical, despite its attempt to present a social reality, is a problem play, a social drama touching social issues--realistic in approach, but the representation seems like an editorial. In the final analysis, The Care Divas is argued to seemingly fail because artists are not able to see the complexity of their chosen subject in a bigger picture. PMID:26291029

  19. Microvesicle formulations used in topical drugs and cosmetics affect product efficiency, performance and allergenicity.

    PubMed

    Madsen, Jakob Torp; Andersen, Klaus Ejner

    2010-01-01

    Attempts to improve the formulations of topical products are continuing processes (ie, to increase cosmetic performance, enhance effects, and protect ingredients from degradation). The development of micro- and nanovesicular systems has led to the marketing of topical drugs and cosmetics that use these technologies. Several articles have reported improved clinical efficacy by the encapsulation of pharmaceuticals in vesicular systems, and the numbers of publications and patents are rising. Some vesicular systems may deliver the drug deeper in the skin as compared to conventional vehicles, or even make transdermal delivery more efficient for a number of drugs. Vesicular systems may also allow a more precise drug delivery to the site of action (ie, the hair follicles) and thereby minimize the applied drug concentration, reducing potential side effects. On the other hand, this may increase the risk of other side effects. Few case reports have suggested that microvesicle formulations may affect the allergenicity of topical products. This article gives an overview of the current knowledge about the topical use of microvesicular systems and the dermatoallergologic aspects. PMID:20920408

  20. Cardiovascular and affective consequences of ruminating on a performance stressor depend on mode of thought.

    PubMed

    Zoccola, Peggy M; Rabideau, Erin M; Figueroa, Wilson S; Woody, Alex

    2014-08-01

    Psychological detachment from work is important for facilitating recovery. This can be threatened by rumination, or thinking about the day's stressors. Rumination may lead to distress, fatigue and extended activation of stress-related systems, but findings are not unequivocal. Level of construal (abstract or concrete) and type of mentation (imagery or verbal thought) used during stressor-focused rumination may shape physiological and affective responses and impact recovery. This study tested whether blood pressure (BP) and anxiety responses to stressor-focused rumination differ by mentation type and construal level. Healthy undergraduates (n = 136) performed a speech stressor and then completed a rumination task in one of four randomly assigned conditions: concrete imagery, abstract imagery, concrete verbal thought or abstract verbal thought. Anxiety and continuous BP were assessed. Concrete rumination led to greater BP, whereas rumination with abstract construals led to lower BP. Furthermore, participants in the abstract conditions had greater increases in anxiety following stressor-focused rumination than in the concrete conditions. Results suggest that the immediate physiological and psychological consequences of stressor-focused rumination depend upon mode of thought. PMID:25100270

  1. Capillary Printing of Highly Aligned Silver Nanowire Transparent Electrodes for High-Performance Optoelectronic Devices.

    PubMed

    Kang, Saewon; Kim, Taehyo; Cho, Seungse; Lee, Youngoh; Choe, Ayoung; Walker, Bright; Ko, Seo-Jin; Kim, Jin Young; Ko, Hyunhyub

    2015-12-01

    Percolation networks of silver nanowires (AgNWs) are commonly used as transparent conductive electrodes (TCEs) for a variety of optoelectronic applications, but there have been no attempts to precisely control the percolation networks of AgNWs that critically affect the performances of TCEs. Here, we introduce a capillary printing technique to precisely control the NW alignment and the percolation behavior of AgNW networks. Notably, partially aligned AgNW networks exhibit a greatly lower percolation threshold, which leads to the substantial improvement of optical transmittance (96.7%) at a similar sheet resistance (19.5 Ω sq(-1)) as compared to random AgNW networks (92.9%, 20 Ω sq(-1)). Polymer light-emitting diodes (PLEDs) using aligned AgNW electrodes show a 30% enhanced maximum luminance (33068 cd m(-2)) compared to that with random AgNWs and a high luminance efficiency (14.25 cd A(-1)), which is the highest value reported so far using indium-free transparent electrodes for fluorescent PLEDs. In addition, polymer solar cells (PSCs) using aligned AgNW electrodes exhibit a power conversion efficiency (PCE) of 8.57%, the highest value ever reported to date for PSCs using AgNW electrodes. PMID:26540011

  2. Influence of a bleaching post-exposure treatment in the performance of H-PDLC devices with high electric conductivity

    NASA Astrophysics Data System (ADS)

    Ortuño, Manuel; Márquez, Andrés.; Gallego, Sergi; Fernandez, Roberto; Navarro-Fuster, Víctor; Beléndez, Augusto; Pascual, Inmaculada

    2014-08-01

    Holographic polymer dispersed liquid crystals (H-PDLC) are made by holographic recording in a photo-polymerization induced phase separation process in which the liquid crystal molecules diffuse to dark zones in the diffraction grating. The devices with H-PDLC materials develop a dynamic behavior that may be modified by means of an electric field. We study a photopolymer formulation with high diffraction efficiency but with the problem of high electric conductivity. We use a bleaching post-exposure treatment to obtain devices with a better electro-optical performance.

  3. High optical and switching performance electrochromic devices based on a zinc oxide nanowire with poly(methyl methacrylate) gel electrolytes

    NASA Astrophysics Data System (ADS)

    Chun, Young Tea; Neeves, Matthew; Smithwick, Quinn; Placido, Frank; Chu, Daping

    2014-11-01

    High performance electrochromic devices have been fabricated and demonstrated utilizing a solid polymer electrolyte and zinc oxide (ZnO) nanowire (NW) array counter electrode. The poly(methyl methacrylate) based polymer electrolyte was spin coated upon hydrothermally grown ZnO NW array counter electrodes, while electron beam evaporated NiOx thin films formed the working electrodes. Excellent optical contrast and switching speeds were observed in the fabricated devices with active areas of 2 cm2, exhibiting an optical contrast of 73.11% at the wavelength of 470 nm, combined with a fast switching time of 0.2 s and 0.4 s for bleaching and coloration, respectively.

  4. Performance investigation of bandgap, gate material work function and gate dielectric engineered TFET with device reliability improvement

    NASA Astrophysics Data System (ADS)

    Raad, Bhagwan Ram; Nigam, Kaushal; Sharma, Dheeraj; Kondekar, P. N.

    2016-06-01

    This script features a study of bandgap, gate material work function and gate dielectric engineering for enhancement of DC and Analog/RF performance, reduction in the hot carriers effect (HCEs) and drain induced barrier lowering (DIBL) for better device reliability. In this concern, the use of band gap and gate material work function engineering improves the device performance in terms of the ON-state current and suppressed ambipolar behaviour with maintaining the low OFF-state current. With these advantages, the use of gate material work function engineering imposes restriction on the high frequency performance due to increment in the parasitic capacitances and also introduces the hot carrier effects. Hence, the gate dielectric engineering with bandgap and gate material work function engineering are used in this paper to overcome the cons of the gate material work function engineering by obtaining a superior performance in terms of the current driving capability, ambipolar conduction, HCEs, DIBL and high frequency parameters of the device for ultra-low power applications. Finally, the optimization of length for different work function is performed to get the best out of this.

  5. Affect and Managerial Performance: A Test of the Sadder-but-Wiser vs. Happier-and-Smarter Hypotheses.

    ERIC Educational Resources Information Center

    Staw, Barry M.; Barsade, Sigal G.

    1993-01-01

    Provides a comparative test of two psychological theories concerning the relationship between affect and performance. Used managerial simulations to test whether people with positive dispositions perform better or worse on both decisional and interpersonal tasks. Results support the happier-and-smarter, as opposed to the sadder-but-wiser,…

  6. The design and performance of an experimental external fixation device with load transducers.

    PubMed

    Draper, E R; Wallace, A L; Strachan, R K; Hughes, S P; Nicol, A C; Paul, J P

    1995-12-01

    It is becoming increasingly common that fracture healing is modelled in the laboratory with an osteotomy in the diaphysis of the ovine tibia. External fixation is often used to hold the bones in these models, presenting the problem that the loads on such devices are poorly understood. To help investigate this, a unilateral device has been developed which is capable of measuring the two components of load considered to be the most important, that of axial compression and bending in the plane of the fixator. The device was found to be a rigid system and easy to apply, with the in-vivo measurements being straightforward. The estimated limits of error of the compression transducer are +37.9 N and -21.4 N and those of the bending transducer are +3.6 Nm and -4.2 Nm. Preliminary measurements showed the maximum load during normal walking to 345 N compression and 28 Nm in-plane bending. PMID:8564157

  7. High performance electrical, magnetic, electromagnetic and electrooptical devices enabled by three dimensionally ordered nanodots and nanorods

    DOEpatents

    Goyal, Amit , Kang; Sukill

    2012-02-21

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  8. High performance superconducting devices enabled by three dimensionally ordered nanodots and/or nanorods

    DOEpatents

    Goyal, Amit

    2013-09-17

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  9. High performance devices enabled by epitaxial, preferentially oriented, nanodots and/or nanorods

    DOEpatents

    Goyal, Amit

    2011-10-11

    Novel articles and methods to fabricate same with self-assembled nanodots and/or nanorods of a single or multicomponent material within another single or multicomponent material for use in electrical, electronic, magnetic, electromagnetic, superconducting and electrooptical devices is disclosed. Self-assembled nanodots and/or nanorods are ordered arrays wherein ordering occurs due to strain minimization during growth of the materials. A simple method to accomplish this when depositing in-situ films is also disclosed. Device applications of resulting materials are in areas of superconductivity, photovoltaics, ferroelectrics, magnetoresistance, high density storage, solid state lighting, non-volatile memory, photoluminescence, thermoelectrics and in quantum dot lasers.

  10. Double jeopardy! The additive consequences of negative affect on performance-monitoring decrements following traumatic brain injury.

    PubMed

    Larson, Michael J; Kaufman, David A S; Kellison, Ida L; Schmalfuss, Ilona M; Perlstein, William M

    2009-07-01

    Survivors of severe traumatic brain injury (TBI) are at increased risk for emotional sequelae. The current study utilized the error-related negativity (ERN) and posterror positivity (Pe) components of the event-related potential (ERP) to test the hypothesis that negative affect disproportionately impairs performance-monitoring following severe TBI. High-density ERPs were acquired while 20 survivors of severe TBI and 20 demographically matched controls performed a single-trial Stroop task. Response-locked ERPs were separately averaged for correct and error trials. Negative affect was measured as the single latent factor of measures of depression and anxiety. Groups did not differ on overall level of negative affect. Control and TBI participants did not differ on error rates as a function of negative affect, but differed in response times. ERP results revealed disproportionately smaller ERN amplitudes in participants with TBI relative to controls as a function of negative affect. Pe amplitude did not differ between groups. Negative affect inversely correlated with ERN amplitude in TBI but not control participants. Overall, results support a "double jeopardy" hypothesis of disproportionate impairments in performance monitoring when negative affect is overlaid on severe TBI. PMID:19586208

  11. Feeding Experience of Bemisia tabaci (Hemiptera: Aleyrodidae) Affects Their Performance on Different Host Plants

    PubMed Central

    Shah, M. Mostafizur Rahman; Liu, Tong-Xian

    2013-01-01

    The sweetpotato whitefly, Bemisia tabaci biotype B is extremely polyphagous with >600 species of host plants. We hypothesized that previous experience of the whitefly on a given host plant affects their host selection and performance on the plants without previous experience. We investigated the host selection for feeding and oviposition of adults and development and survival of immatures of three host-plant-experienced populations of B. tabaci, namely Bemisia-eggplant, Bemisia-tomato and Bemisia-cucumber, on their experienced host plant and each of the three other plant species (eggplant, tomato, cucumber and pepper) without previous experience. We found that the influence of previous experience of the whiteflies varied among the populations. All populations refused pepper for feeding and oviposition, whereas the Bemisia-cucumber and the Bemisia-eggplant strongly preferred cucumber. Bemisia-tomato did not show strong preference to any of the three host palnts. Development time from egg to adult eclosion varied among the populations, being shortest on eggplant, longest on pepper, and intermediate on tomato and cucumber except for the Bemisia-cucumber developed similarly on tomato and pepper. The survivorship from egg to adult eclosion of all populations was highest on eggplant (80-98%), lowest on pepper (0-20%), and intermediate on tomato and cucumber. In conclusion, the effects of previous experience of whiteflies on host selection for feeding and oviposition, development, and survivorship varied depending on host plants, and host plants play a stronger role than previous experience. Preference of feeding and oviposition by adults may not accurately reflect host suitability of immatures. These results provided important information for understanding whitefly population dynamics and dispersal among different crop systems. PMID:24146985

  12. Planar source pocket (PSP) tunnel MOSFET: Potential device solution for low power applications and improving tunneling MOSFET performance

    NASA Astrophysics Data System (ADS)

    Nagavarapu, Venkatagirish

    As MOSFET is scaled below 90nm, many daunting challenges arise. Short channel effects (DIBL and VTH roll-off), off-state leakage, parasitic capacitance and resistance severely limit the performance of these transistors. Moreover as the device dimensions are being scaled down into the nanometer regime, power dissipation is becoming a principal concern. Supply voltage scaling constraints and the diffusion limit of 60mv/dec on the sub-threshold swing (SS) lead to reduced ION/IOFF and high I OFF. This leads to higher active power dissipation and sub-threshold power consumption. To provide for a given overdrive and control power dissipation, lower threshold voltage is required while maintaining a low IOFF. This points to the pressing need for devices with steep (< 60mv/dec) sub-threshold behavior. New device innovations are essential to overcome these challenges. In recent years, research in novel devices (tunneling FETs, IMOS [1], [2]) for possible solutions towards providing steep sub-threshold behavior and improved ION at lower operating voltages has gained a lot of momentum. Most of the tunneling devices investigated have the configuration of gate controlled reverse biased p-i-n diodes ([3] - [8

  13. Assessment of the performance of a handheld Raman device for potential use as a screening tool in evaluating medicines quality.

    PubMed

    Hajjou, Mustapha; Qin, Yanyan; Bradby, Sanford; Bempong, Daniel; Lukulay, Patrick

    2013-02-23

    The TruScan(®) handheld Raman device is used for testing finished pharmaceutical products in the field to detect counterfeit and substandard medicines. Present work reports on the device's ability to discriminate between a specific product and similar products from different manufacturers, unrelated medicines, and medicines with different strengths. This investigation evaluated its ability to differentiate between similar drug products of similar or different strengths, focusing on the specificity and precision of the testing. First, several units of the same medicine's dosage form were compared; then comparisons were made between unrelated products, similar products, and products with different strengths. The six pharmaceutical products used in testing were from commonly used analgesic, antimalarial, and antidiarrheal medicines. The results showed that the performance of the TruScan(®) device depends on the nature and the strength of the dosage form tested; while the device could be suitable for authentication of some finished pharmaceutical products and, hence, could be used to detect some counterfeit medicines, it could not be used to detect substandard medicines. Careful consideration should be given when using the device as a screening tool for counterfeit medicines. PMID:23245232

  14. Exposure to Cerium Dioxide Nanoparticles Differently Affect Swimming Performance and Survival in Two Daphnid Species

    PubMed Central

    Artells, Ester; Issartel, Julien; Auffan, Mélanie; Borschneck, Daniel; Thill, Antoine; Tella, Marie; Brousset, Lenka; Rose, Jérôme; Bottero, Jean-Yves; Thiéry, Alain

    2013-01-01

    The CeO2 NPs are increasingly used in industry but the environmental release of these NPs and their subsequent behavior and biological effects are currently unclear. This study evaluates for the first time the effects of CeO2 NPs on the survival and the swimming performance of two cladoceran species, Daphnia similis and Daphnia pulex after 1, 10 and 100 mg.L−1 CeO2 exposures for 48 h. Acute toxicity bioassays were performed to determine EC50 of exposed daphnids. Video-recorded swimming behavior of both daphnids was used to measure swimming speeds after various exposures to aggregated CeO2 NPs. The acute ecotoxicity showed that D. similis is 350 times more sensitive to CeO2 NPs than D. pulex, showing 48-h EC50 of 0.26 mg.L−1 and 91.79 mg.L−1, respectively. Both species interacted with CeO2 NPs (adsorption), but much more strongly in the case of D. similis. Swimming velocities (SV) were differently and significantly affected by CeO2 NPs for both species. A 48-h exposure to 1 mg.L−1 induced a decrease of 30% and 40% of the SV in D. pulex and D. similis, respectively. However at higher concentrations, the SV of D. similis was more impacted (60% off for 10 mg.L−1 and 100 mg.L−1) than the one of D. pulex. These interspecific toxic effects of CeO2 NPs are explained by morphological variations such as the presence of reliefs on the cuticle and a longer distal spine in D. similis acting as traps for the CeO2 aggregates. In addition, D. similis has a mean SV double that of D. pulex and thus initially collides with twice more NPs aggregates. The ecotoxicological consequences on the behavior and physiology of a CeO2 NPs exposure in daphnids are discussed. PMID:23977004

  15. Factors affecting the stability and performance of ionic liquid-based planar transient photodetectors.

    PubMed

    Dalgleish, Simon; Reissig, Louisa; Hu, Laigui; Matsushita, Michio M; Sudo, Yuki; Awaga, Kunio

    2015-05-12

    A novel planar architecture has been developed for the study of photodetectors utilizing the transient photocurrent response induced by a metal/insulator/semiconductor/metal (MISM) structured device, where the insulator is an ionic liquid (IL-MISM). Using vanadyl 2,3-naphthalocyanine, which absorbs in the communications-relevant near-infrared wavelength region (λ(max,film) ≈ 850 nm), in conjunction with C60 as a bulk heterojunction, the high capacitance of the formed electric double layers at the ionic liquid interfaces yields high charge separation efficiency within the semiconductor layer, and the minimal potential drop in the bulk ionic liquid allows the electrodes to be offset by distances of over 7 mm. Furthermore, the decrease in operational speed with increased electrode separation is beneficial for a clear modeling of the waveform of the photocurrent signal, free from the influence of measurement circuitry. Despite the use of a molecular semiconductor as the active layer in conjunction with a liquid insulating layer, devices with a stability of several days could be achieved, and the operational stability of such devices was shown to be dependent solely on the solubility of the active layer in the ionic liquid, even under atmospheric conditions. Furthermore, the greatly simplified device construction process, which does not rely on transparent electrode materials or direct electrode deposition, provides a highly reproducible platform for the study of the electronic processes within IL-MISM detectors that is largely free from architectural constraints. PMID:25895167

  16. Performance of a Novel Bipolar/Monopolar Radiofrequency Ablation Device on the Beating Heart in an Acute Porcine Model

    PubMed Central

    Saint, Lindsey L.; Lawrance, Christopher P.; Okada, Shoichi; Kazui, Toshinobu; Robertson, Jason O.; Schuessler, Richard B.; Damiano, Ralph J.

    2013-01-01

    SUMMARY Objective Although the advent of ablation technology has simplified and shortened surgery for atrial fibrillation, only bipolar clamps have reliably been able to create transmural lesions on the beating heart. Currently there are no devices capable of reproducibly creating the long linear lesions in the right and left atria needed to perform a Cox-Maze procedure. This study evaluated the performance of a novel suction-assisted radiofrequency device that uses both bipolar and monopolar energy to create lesions from an epicardial approach on the beating heart. Methods Six domestic pigs underwent median sternotomy. A dual bipolar/monopolar radiofrequency ablation device was used to create epicardial linear lesions on the superior and inferior vena cavae, right and left atrial free walls, and right and left atrial appendages. The heart was stained with 2,3,5-triphenyl-tetrazolium chloride and each lesion was cross-sectioned at 5mm intervals. Lesion depth and transmurality were determined. Results Transmurality was documented in 94% of all cross-sections, and 68% of all ablation lines were transmural along their entire length. Tissue thickness was not different between transmural and non-transmural cross-sections (3.1 ± 1.3 and 3.4 ± 2.1, p=0.57, respectively), nor was the anatomic location on the heart (p=0.45 for the distribution). Of the cross-sections located at the end of the ablation line, 11% (8/75) were found to be non-transmural, whereas only 4% (8/195) of cross-sections located within the line of ablation were found to be non-transmural (p=0.04). Logistic regression analysis demonstrated that failure of the device to create transmural lesions was associated with low body temperature (p=0.006), but not with cardiac output (p=0.54). Conclusions This novel device was able to consistently create transmural epicardial lesions on the beating heart, regardless of anatomic location, cardiac output or tissue thickness. The performance of this device was

  17. The Effect of Asterisks as an Attention Focusing Device on Test Performance of Undergraduate Students.

    ERIC Educational Resources Information Center

    Perrin, David W.; Kerasotes, Dean L.

    It was hypothesized that using asterisks as attention focusing devices would cause students to read all asteriked test items more carefully and would improve test scores of undergraduate education students. Sixty-three undergraduates majoring in elementary or special education were administered a 36-item objective test. Asterisks were used to…

  18. A Device for Performing Lateral Conductance Measurements on Individual Double-Stranded DNA Molecules

    PubMed Central

    Menard, Laurent D.; Mair, Chad E.; Woodson, Michael E.; Alarie, Jean Pierre; Ramsey, J. Michael

    2012-01-01

    A nanofluidic device is described that is capable of electrically monitoring the driven translocation of DNA molecules through a nanochannel. This is achieved by intersecting a long transport channel with a shorter orthogonal nanochannel. The ionic conductance of this transverse nanochannel is monitored while DNA is electrokinetically driven through the transport channel. When DNA passes the intersection, the transverse conductance is altered, resulting in a transient current response. In 1 M KCl solutions, this was found to be a current enhancement of 5–25%, relative to the baseline transverse ionic current. Two different device geometries were investigated. In one device, the DNA was detected after it was fully inserted into and translocating through the transport nanochannel. In the other device, the DNA was detected while it was in the process of entering the nanochannel. It was found that these two conditions are characterized by different transport dynamics. Simultaneous optical and electrical monitoring of DNA translocation confirmed that the transient events originated from DNA transport through the nanochannel intersection. PMID:22950784

  19. The performance characteristics of lateral flow devices with 2 strains of highly pathogenic avian influenza virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Lateral flow devices (LFD) are commercially available and provide a fast, highly specific, on-site test for avian influenza. Because of the low analytic sensitivity of LFD tests at low virus concentrations, targeted sampling of sick and dead birds has been proposed in order to increase detection pr...

  20. Rational material, interface, and device engineering for high-performance polymer and perovskite solar cells (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Jen, Alex K.

    2015-10-01

    The performance of polymer and hybrid solar cells is also strongly dependent on their efficiency in harvesting light, exciton dissociation, charge transport, and charge collection at the metal/organic/metal oxide or the metal/perovskite/metal oxide interfaces. Our laboratory employs a molecular engineering approach to develop processible low band-gap polymers with high charge carrier mobility that can enhance power conversion efficiency of the single junction solar cells to values as high as ~11%. We have also developed several innovative strategies to modify the interface of bulk-heterojunction devices and create new device architectures to fully explore their potential for solar applications. In this talk, the integrated approach of combining material design, interface, and device engineering to significantly improve the performance of polymer and hybrid perovskite photovoltaic cells will be discussed. Specific emphasis will be placed on the development of low band-gap polymers with reduced reorganizational energy and proper energy levels, formation of optimized morphology of active layer, and minimized interfacial energy barriers using functional conductive surfactants. At the end, several new device architectures and optical engineering strategies to make tandem cells and semitransparent solar cells will be discussed to explore the full promise of polymer and perovskite hybrid solar cells.

  1. Effect of the application of an electric field on the performance of a two-phase loop device: preliminary results

    NASA Astrophysics Data System (ADS)

    Creatini, F.; Di Marco, P.; Filippeschi, S.; Fioriti, D.; Mameli, M.

    2015-11-01

    In the last decade, the continuous development of electronics has pointed out the need for a change in mind with regard to thermal management. In the present scenario, Pulsating Heat Pipes (PHPs) are novel promising two-phase passive heat transport devices that seem to meet all present and future thermal requirements. Nevertheless, PHPs governing phenomena are quite unique and not completely understood. In particular, single closed loop PHPs manifest several drawbacks, mostly related to the reduction of device thermal performance and reliability, i.e. the occurrence of multiple operational quasi-steady states. The present research work proposes the application of an electric field as a technique to promote the circulation of the working fluid in a preferential direction and stabilize the device operation. The tested single closed loop PHP is made of a copper tube with an inner tube diameter equal to 2.00 mm and filled with pure ethanol (60% filling ratio). The electric field is generated by a couple of wire-shaped electrodes powered with DC voltage up to 20 kV and laid parallel to the longitudinal axis of the glass tube constituting the adiabatic section. Although the electric field intensity in the working fluid region is weakened both by the polarization phenomenon of the working fluid and by the interposition of the glass tube, the experimental results highlight the influence of the electric field on the device thermal performance and encourage the continuation of the research in this direction.

  2. The effects of electrode cleaning and conditioning on the performance of high-energy, pulsed-power devices

    SciTech Connect

    Cuneo, M.E.

    1998-09-01

    High-energy pulsed-power devices routinely access field strengths above those at which broad-area, cathode-initiated, high-voltage vacuum-breakdown occur (> 1e7--3e7 V/m). Examples include magnetically-insulated-transmission-lines and current convolutes, high-current-density electron and ion diodes, high-power microwave devices, and cavities and other structures for electrostatic and RF accelerators. Energy deposited in anode surfaces may exceed anode plasma thermal-desorption creation thresholds on the time-scale of the pulse. Stimulated desorption by electron or photon bombardment can also lead to plasma formation on electrode or insulator surfaces. Device performance is limited above these thresholds, particularly in pulse length and energy, by the formation and expansion of plasmas formed primarily from electrode contaminants. In-situ conditioning techniques to modify and eliminate the contaminants through multiple high-voltage pulses, low base pressures, RF discharge cleaning, heating, surface coatings, and ion- and electron-beam surface treatment allow access to new regimes of performance through control of plasma formation and modification of the plasma properties. Experimental and theoretical progress from a variety of devices and small scale experiments with a variety of treatment methods will be reviewed and recommendations given for future work.

  3. Performance characteristics of a novel megavoltage cone-beam-computed tomography device.

    PubMed

    Fast, M F; Koenig, T; Oelfke, U; Nill, S

    2012-02-01

    In this work, the image quality of a novel megavoltage cone-beam-computed tomography (CBCT) scanner is compared to three other image-guided radiation therapy devices by analysing images of different-sized quality assurance phantoms. The following devices are compared in terms of image uniformity, signal-to-noise ratio, contrast-to-noise ratio (CNR), electron density to HU conversion, presampling modulation transfer function (MTF(pre)) and combined spatial resolution and noise (Q-factor): (i) the Siemens Artiste kilovoltage (kV) (121 kV) CBCT device, (ii) the Artiste treatment beam line (TBL), 6 MV, (iii) the Tomotherapy (3.5 MV) fan-beam CT and (iv) Siemens' novel approach using a carbon target for a dedicated imaging beam line (IBL), 4.2 MV. Machine settings were selected to produce the same imaging dose for all devices. For a head phantom, IBL scans display CNR values 2.6 ± 0.3 times higher than for the TBL at the same dose level (for a CT-number range of -200 to -60 HU). kV CBCT, on the other hand, displays CNR values 7.9 ± 0.3 times higher than the IBL. There was no significant deviation in spatial resolution between IBL, TBL and Tomotherapy in terms of 50% and 10% MTF(pre). For kV CBCT, the MTF(pre) was significantly higher than those for other devices. In our Q-factor analysis, the IBL (14.6) scores higher than the TBL (7.9) and Tomotherapy (9.7) due to its lower noise level. The linearity of electron density to HU conversion is demonstrated for different-sized phantoms. Employing the IBL instead of the TBL significantly reduces the imaging dose by up to a factor of 5 at a constant image quality level, providing an immediate benefit for the patient. PMID:22251668

  4. How does breathing frequency affect the performance of an N95 filtering facepiece respirator and a surgical mask against surrogates of viral particles?

    PubMed

    He, Xinjian; Reponen, Tiina; McKay, Roy; Grinshpun, Sergey A

    2014-01-01

    Breathing frequency (breaths/min) differs among individuals and levels of physical activity. Particles enter respirators through two principle penetration pathways: faceseal leakage and filter penetration. However, it is unknown how breathing frequency affects the overall performance of N95 filtering facepiece respirators (FFRs) and surgical masks (SMs) against viral particles, as well as other health-relevant submicrometer particles. A FFR and SM were tested on a breathing manikin at four mean inspiratory flows (MIFs) (15, 30, 55, and 85 L/min) and five breathing frequencies (10, 15, 20, 25, and 30 breaths/min). Filter penetration (Pfilter) and total inward leakage (TIL) were determined for the tested respiratory protection devices against sodium chloride (NaCl) aerosol particles in the size range of 20 to 500 nm. "Faceseal leakage-to-filter" (FLTF) penetration ratios were calculated. Both MIF and breathing frequency showed significant effects (p < 0.05) on Pfilter and TIL. Increasing breathing frequency increased TIL for the N95 FFR whereas no clear trends were observed for the SM. Increasing MIF increased Pfilter and decreased TIL resulting in decreasing FLTF ratio. Most of FLTF ratios were >1, suggesting that the faceseal leakage was the primary particle penetration pathway at various breathing frequencies. Breathing frequency is another factor (besides MIF) that can significantly affect the performance of N95 FFRs, with higher breathing frequencies increasing TIL. No consistent trend of increase or decrease of TIL with either MIF or breathing frequency was observed for the tested SM. To potentially extend these findings beyond the manikin/breathing system used, future studies are needed to fully understand the mechanism causing the breathing frequency effect on the performance of respiratory protection devices on human subjects. PMID:24521067

  5. Evaluation of factors affecting the containment performance of traditional and nanomaterial fume hoods

    NASA Astrophysics Data System (ADS)

    Dunn, Kevin Holden

    This research was conducted to: 1) evaluate different methods for measuring containment effectiveness of a nanomaterial handling enclosure; 2) to evaluate design and operational factors which may impact containment performance for a traditional constant air volume (CAV) and nano fume using computational fluid dynamics (CFD), and; 3) to assess the impact on the operator body and arm motion on nanoparticle containment of the CAV and nano fume hoods. The research approach to address these objectives starts with an evaluation of the containment effectiveness of a new nanomaterial handling enclosure using tracer gas, nanoparticle and nanoparticle handling methodologies in a real-world laboratory setting. The tracer gas and nanoparticle test results were well-correlated showing hood leakage under the same conditions and at the same sample locations. However, the nanoparticle method was more sensitive than the tracer gas test showing leakage in situations not indicated by the tracer gas tests. These experiments also identified substantial leaks near the sides of the hood sides even when the tracer gas concentration in the manikin breathing zone was not elevated. This result was consistent with new research showing that sampling in the manikin breathing zone may not be adequate to describe containment of fume hood devices. The second phase of this project provides an assessment of the internal flow patterns of a nano fume hood and a traditional CAV chemical fume hood. The impacts of design and operational differences between these hoods are investigated using both experimental measurements and numerical simulations with CFD. An investigation of the airflow patterns inside the hoods showed that large scale recirculation zones develop behind the sash for both hoods. However, the design of the side airfoils of the nano hood resulted in a secondary recirculation pattern along the sides of the hood which impacts interior contaminant dispersion and potential for leakage. The

  6. An Analysis of Factors Affecting Teacher Attrition in High Performing and Low Performing Elementary Rural Schools in South Carolina

    ERIC Educational Resources Information Center

    Carter-Blocker, Vickie R.

    2012-01-01

    The purpose of this study was to examine the factors impacting teacher attrition in high-performing and low-performing elementary rural schools in South Carolina. Several factors were identified that interfered with teachers returning to the teaching profession. School districts in rural areas need to be better informed of the factors that affect…

  7. Tablet Keyboard Configuration Affects Performance, Discomfort and Task Difficulty for Thumb Typing in a Two-Handed Grip.

    PubMed

    Trudeau, Matthieu B; Catalano, Paul J; Jindrich, Devin L; Dennerlein, Jack T

    2013-01-01

    When holding a tablet computer with two hands, the touch keyboard configuration imposes postural constraints on the user because of the need to simultaneously hold the device and type with the thumbs. Designers have provided users with several possible keyboard configurations (device orientation, keyboard layout and location). However, potential differences in performance, usability and postures among these configurations have not been explored. We hypothesize that (1) the narrower standard keyboard layout in the portrait orientation leads to lower self-reported discomfort and less reach than the landscape orientation; (2) a split keyboard layout results in better overall outcomes compared to the standard layout; and (3) the conventional bottom keyboard location leads to the best outcomes overall compared to other locations. A repeated measures laboratory experiment of 12 tablet owners measured typing speed, discomfort, task difficulty, and thumb/wrist joint postures using an active marker system during typing tasks for different combinations of device orientation (portrait and landscape), keyboard layout (standard and split), and keyboard location (bottom, middle, top). The narrower standard keyboard with the device in the portrait orientation was associated with less discomfort (least squares mean (and S.E.) 2.9±0.6) than the landscape orientation (4.5±0.7). Additionally, the split keyboard decreased the amount of reaching required by the thumb in the landscape orientation as defined by a reduced range of motion and less MCP extension, which may have led to reduced discomfort (2.7±0.6) compared to the standard layout (4.5±0.7). However, typing speed was greater for the standard layout (127±5 char./min.) compared to the split layout (113±4 char./min.) regardless of device orientation and keyboard location. Usage guidelines and designers can incorporate these findings to optimize keyboard design parameters and form factors that promote user performance and

  8. Tablet Keyboard Configuration Affects Performance, Discomfort and Task Difficulty for Thumb Typing in a Two-Handed Grip

    PubMed Central

    Trudeau, Matthieu B.; Catalano, Paul J.; Jindrich, Devin L.; Dennerlein, Jack T.

    2013-01-01

    When holding a tablet computer with two hands, the touch keyboard configuration imposes postural constraints on the user because of the need to simultaneously hold the device and type with the thumbs. Designers have provided users with several possible keyboard configurations (device orientation, keyboard layout and location). However, potential differences in performance, usability and postures among these configurations have not been explored. We hypothesize that (1) the narrower standard keyboard layout in the portrait orientation leads to lower self-reported discomfort and less reach than the landscape orientation; (2) a split keyboard layout results in better overall outcomes compared to the standard layout; and (3) the conventional bottom keyboard location leads to the best outcomes overall compared to other locations. A repeated measures laboratory experiment of 12 tablet owners measured typing speed, discomfort, task difficulty, and thumb/wrist joint postures using an active marker system during typing tasks for different combinations of device orientation (portrait and landscape), keyboard layout (standard and split), and keyboard location (bottom, middle, top). The narrower standard keyboard with the device in the portrait orientation was associated with less discomfort (least squares mean (and S.E.) 2.9±0.6) than the landscape orientation (4.5±0.7). Additionally, the split keyboard decreased the amount of reaching required by the thumb in the landscape orientation as defined by a reduced range of motion and less MCP extension, which may have led to reduced discomfort (2.7±0.6) compared to the standard layout (4.5±0.7). However, typing speed was greater for the standard layout (127±5 char./min.) compared to the split layout (113±4 char./min.) regardless of device orientation and keyboard location. Usage guidelines and designers can incorporate these findings to optimize keyboard design parameters and form factors that promote user performance and

  9. Performance of charge-injection-device infrared detector arrays at low and moderate backgrounds

    NASA Technical Reports Server (NTRS)

    Mckelvey, M. E.; Mccreight, C. R.; Goebel, J. H.; Reeves, A. A.

    1985-01-01

    Three 2 x 64 element charge injection device infrared detector arrays were tested at low and moderate background to evaluate their usefulness for space based astronomical observations. Testing was conducted both in the laboratory and in ground based telescope observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3x10 sq root of W/Hz. Array well capacity was measured to be significantly smaller than predicted. The measured sensitivity, which compares well with that of nonintegrating discrete extrinsic silicon photoconductors, shows these arrays to be useful for certain astronomical observations. However, the measured readout efficiency and frequency response represent serious limitations in low background applications.

  10. Stoichiometric control of lead chalcogenide nanocrystal solids to enhance their electronic and optoelectronic device performance.

    PubMed

    Oh, Soong Ju; Berry, Nathaniel E; Choi, Ji-Hyuk; Gaulding, E Ashley; Paik, Taejong; Hong, Sung-Hoon; Murray, Christopher B; Kagan, Cherie R

    2013-03-26

    We investigate the effects of stoichiometric imbalance on the electronic properties of lead chalcogenide nanocrystal films by introducing excess lead (Pb) or selenium (Se) through thermal evaporation. Hall-effect and capacitance-voltage measurements show that the carrier type, concentration, and Fermi level in nanocrystal solids may be precisely controlled through their stoichiometry. By manipulating only the stoichiometry of the nanocrystal solids, we engineer the characteristics of electronic and optoelectronic devices. Lead chalcogenide nanocrystal field-effect transistors (FETs) are fabricated at room temperature to form ambipolar, unipolar n-type, and unipolar p-type semiconducting channels as-prepared and with excess Pb and Se, respectively. Introducing excess Pb forms nanocrystal FETs with electron mobilities of 10 cm(2)/(V s), which is an order of magnitude higher than previously reported in lead chalcogenide nanocrystal devices. Adding excess Se to semiconductor nanocrystal solids in PbSe Schottky solar cells enhances the power conversion efficiency. PMID:23368728

  11. Charge-injection-device 2 x 64 element infrared array performance

    NASA Technical Reports Server (NTRS)

    Mckelvey, M. E.; Mccreight, C. R.; Goebel, J. H.; Reeves, A. A.

    1985-01-01

    Three 2 x 64 element Si:Bi accumulation-mode charge-injection-device (CID) arrays were tested at low and moderate background to evaluate their usefulness for space-based astronomical observations. Testing was conducted both in the laboratory and in ground-based telescope IR observations. The devices showed an average readout noise level below 200 equivalent electrons, a peak responsivity of 4 A/W, and a noise equivalent power of 3 x 10 to the -17th W/sq rt Hz. This sensitivity compares well with that of nonintegrating discrete extrinsic silicon photoconductors. The array well capacity was significantly smaller than predicted. The measured sensitivity makes extrinsic silicon CID arrays useful for certain astronomical applications. However, their readout efficiency and frequency response represent serious limitations in low-background applications.

  12. Survey of liquid-level detection devices used in safeguards and their performance values

    SciTech Connect

    Suda, S.; Keisch, B.

    1994-03-01

    Liquid-level detection devices commonly used in safeguards for measuring the liquid volume in a tank were investigated. The study addressed physical models, limitations and advantages, measurement uncertainties, and measurement control techniques. Volume measurements are necessary to determine the amounts of material in liquids in process tanks. To calculate the volume, a calibration curve is used to relate volume to liquid height. Calibration curves depend on the geometric shape of the tank. For a closed process tank, the distance from the bottom of the tank to the liquid surface (i.e., height) in general cannot be measured directly. Level measurement devices can be grouped according to four measurement points of reference. These are: tip of probe, length of submerged probe, top of tank, and liquid surface. Level detection techniques corresponding to these measurement points are pressure, electrical characteristics of the probe, sonic reflections, and visual scales.

  13. High-Performance Three-Stage Cascade Thermoelectric Devices with 20% Efficiency

    NASA Astrophysics Data System (ADS)

    Cook, B. A.; Chan, T. E.; Dezsi, G.; Thomas, P.; Koch, C. C.; Poon, J.; Tritt, T.; Venkatasubramanian, R.

    2015-06-01

    The use of advanced materials has resulted in a significant improvement in thermoelectric device conversion efficiency. Three-stage cascade devices were assembled, consisting of nano-bulk Bi2Te3-based materials on the cold side, PbTe and enhanced TAGS-85 [(AgSbTe2)15(GeTe)85] for the mid-stage, and half-Heusler alloys for the high-temperature top stage. In addition, an area aspect ratio optimization process was applied in order to account for asymmetric thermal transport down the individual n- and p-legs. The n- and p-type chalcogenide alloy materials were prepared by high-energy mechanical ball-milling and/or cryogenic ball-milling of elementary powders, with subsequent consolidation by high-pressure uniaxial hot-pressing. The low-temperature stage materials, nano-bulk Bi2Te3- x Sb x and Bi2Te3- x Se x , exhibit a unique mixture of nanoscale features that leads to an enhanced Seebeck coefficient and reduced lattice thermal conductivity, thereby achieving an average ZT of ~1.26 and ~1.7 in the 27°C to 100°C range for the n-type and p-type materials, respectively. Also, the addition of small amounts of selected rare earth elements has been shown to improve the ZT of TAGS-85 by 25%, compared with conventional or neat TAGS-85, resulting in a ZT = 1.5 at 400°C. The incorporation of these improved materials resulted in a peak device conversion efficiency of ~20% at a temperature difference of 750°C when corrected for radiation heat losses and thermal conduction losses through the lead wires. These high-efficiency results were shown to be reproducible across multiple cascade devices.

  14. A new continuous device to perform S-L-G photocatalytic studies. [Solid-Liquid-Gas

    SciTech Connect

    Aguado, M.A.; Gimenez, J.; Simarro, R.; Cervera-March, S. )

    1992-07-01

    A new experimental device to carry out solid-liquid-gas photocatalytic studies is presented. It can operate as a continuous system with respect to both the gas and the liquid phase. The solid photocatalyst is held inside the system and is continuously recycled through it to enable the separation of the spent liquid. Steady values of liquid and gas composition as well as temperature and fluidodynamic variables can be set and controlled.

  15. Effect of cuprous halide interlayers on the device performance of ZnPc/C{sub 60} organic solar cells

    SciTech Connect

    Lee, Jinho; Park, Dasom; Heo, Ilsu; Yim, Sanggyu

    2014-10-15

    Highlights: • Effect of CuX interlayers on subsequently deposited films and devices was studied. • CuI is the most effective for the performance of ZnPc/C{sub 60}-based solar cells. • Results were related to the molecular geometry of ZnPc and HOMO level of interlayers. - Abstract: The effect of various cuprous halide (CuX) interlayers introduced between a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) layer and zinc phthalocyanine (ZnPc) layer on the physical properties of the ZnPc thin films and device performances of ZnPc/C{sub 60}-based small-molecule organic solar cells was studied. Strong substrate–molecule interaction between the CuX and ZnPc partly converted surface-perpendicular stacking geometry of ZnPc molecules into surface-parallel one. This flat-lying geometry led to an enhancement in electronic absorption and charge transport within the ZnPc films. As a result, the overall power conversion efficiency of the cell with CuI interlayer increased by ∼37%. In the case of the cells with CuBr and CuCl interlayer, however, the enhancement in device performances was limited because of the reduced conversion of the molecular geometry and increased energy barrier for hole extraction due to the low highest occupied molecular orbital level of the interlayer.

  16. Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads

    PubMed Central

    Vázquez-Guerrero, Jairo; Moras, Gerard

    2016-01-01

    The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries. PMID:27111766

  17. The performance of smooth-wall drag reducing outer-layer devices in rough-wall boundary layers

    NASA Technical Reports Server (NTRS)

    Bandyopadhyay, P. R.

    1985-01-01

    The boundary layer drag on a 0.28 m x 0.91 m flat-plate was measured to evaluate the performance of smooth-wall drag reducing outer-layer devices in rough-wall boundary layers up to a chord Reynolds number, Re(c) of 17,000. The devices were a pair of thin flat ribbons placed in tandem. The wall conditions examined were smooth, transverse-groove roughnesses having cavity width/depth ratios of 0.7 (d-type) and 3 (k-type), and sandpaper roughness (k-type) of grit sizes 180, 50 and 36. The area-averaged wall-drag was reduced compared to the respective normal levels for all wall conditions. All k-type rough walls exhibited a comparable level of drag reduction (about 7 percent) which was lower than that in the smooth-wall. The d-type rough-wall exhibited a transitional behavior in that the drag reduction dropped from the smooth-wall level to that of the k-type roughnesses with increase in the flow speed. In further experiments on a 6 meter long sandpaper roughened wall and with a pair of symmetric airfoil devices in tandem at an Re(c) of 77,500, it was possible to recover the device drag penalty fully, but no net drag reduction was achieved. The apparent loss of performance of the devices in a rough-wall is explained in terms of their inability to alter the pressure component of the drag in a significant way.

  18. Harnessing Structure-Property Relationships for Poly(alkyl thiophene)-Fullerene Derivative Thin Filmsto Optimize Performance in Photovoltaic Devices

    DOE PAGESBeta

    Deb, Nabankur; Li, Bohao; Skoda, Maximilian; Rogers, Sarah; Sun, Yan; Gong, Xiong; Karim, Alamgir; Sumpter, Bobby G.; Bucknall, David G.

    2016-02-08

    Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers as the active component, have been actively studied over the last decades in order to produce high performance organic photovoltaics (OPVs). A significant role in device efficiency is played by the active layer morphology, but despite considerable study, a full understanding of the exact role that morphology plays and therefore a definitive method to produce and control an ideal morphology is lacking. In order to understand the BHJ phase behavior and associated morphology in these devices, we have used neutron reflection, together with grazing incidence X-ray and neutronmore » scattering and X-ray photoelectron spectroscopy (XPS) to determine the morphology of the BHJ active layer in functional devices. We have studied nine model BHJ systems based on mixtures of three poly(3-alkyl thiophenes, P3AT) (A=butyl, hexyl, octyl) blended with three different fullerene derivatives, which provides variations in crystallinity and miscibility within the BHJ composite. In studying properties of functional devices, we show a direct correlation between the observed morphology within the BHJ layer and the device performance metrics, i.e., the short-circuit current (JSC), fill factor (FF), open-circuit voltage (VOC) and overall power conversion efficiency (PCE). Using these model systems, the effect of typical thermal annealing processes on the BHJ morphology through the film thickness as a function of the polythiophene-fullerene mixtures and different electron transport layer interfaces has been determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with JSC and to a lesser degree with FF. Finally, based on these findings we demonstrate that by deliberately adding a fullerene layer at the electron transport layer interface, JSC can be increased by up to 20

  19. Aerodynamic performance of a drag reduction device on a full-scale tractor/trailer

    NASA Astrophysics Data System (ADS)

    Lanser, Wendy R.; Ross, James C.; Kaufman, Andrew E.

    1991-09-01

    The effectiveness of an aerodynamic boattail on a tractor/trailer road vehicle was measured in the NASA Ames Research Center 80- by 120-Foot Wind Tunnel. Results are examined for the tractor/trailer with and without the drag reduction device. Pressure measurements and flow visualization show that the aerodynamic boattail traps a vortex or eddy in the corner formed between the device and the rear corner of the trailer. This recirculating flow turns the flow inward as it separates from the edges of the base of the trailer. This modified flow behavior increases the pressure acting over the base area of the truck, thereby reducing the net aerodynamic drag of the vehicle. Drag measurements and pressure distributions in the region of the boattail device are presented for selected configurations. The optimum configuration reduces the overall drag of the tractor/trailer combination by about 10 percent at a zero yaw angle. Unsteady pressure measurements do not indicate strong vortex shedding, although the addition of the boattail plates increases high frequency content of the fluctuating pressure.

  20. Surgical virtual reality - highlights in developing a high performance surgical haptic device.

    PubMed

    Custură-Crăciun, D; Cochior, D; Constantinoiu, S; Neagu, C

    2013-01-01

    Just like simulators are a standard in aviation and aerospace sciences, we expect for surgical simulators to soon become a standard in medical applications. These will correctly instruct future doctors in surgical techniques without there being a need for hands on patient instruction. Using virtual reality by digitally transposing surgical procedures changes surgery in are volutionary manner by offering possibilities for implementing new, much more efficient, learning methods, by allowing the practice of new surgical techniques and by improving surgeon abilities and skills. Perfecting haptic devices has opened the door to a series of opportunities in the fields of research,industry, nuclear science and medicine. Concepts purely theoretical at first, such as telerobotics, telepresence or telerepresentation,have become a practical reality as calculus techniques, telecommunications and haptic devices evolved,virtual reality taking a new leap. In the field of surgery barrier sand controversies still remain, regarding implementation and generalization of surgical virtual simulators. These obstacles remain connected to the high costs of this yet fully sufficiently developed technology, especially in the domain of haptic devices. PMID:24331310

  1. Interfacial Morphology and Effects on Device Performance of Organic Bilayer Heterojunction Solar Cells

    PubMed Central

    2015-01-01

    The effects of interface roughness between donor and acceptor in a bilayer heterojunction solar cell were investigated on a polymer–polymer system based on poly(3-hexylthiophene) (P3HT) and poly(dioctylfluorene-alt-benzothiadiazole) (F8BT). Both polymers are known to reorganize into semicrystalline structures when heated above their glass-transition temperature. Here, the bilayers were thermally annealed below glass transition of the bulk polymers (≈140 °C) at temperatures of 90, 100, and 110 °C for time periods from 2 min up to 250 min. No change of crystallinity could be observed at those temperatures. However, X-ray reflectivity and device characteristics reveal a coherent trend upon heat treatment. In X-ray reflectivity investigations, an increasing interface roughness between the two polymers is observed as a function of temperature and annealing time, up to a value of 1 nm. Simultaneously, according bilayer devices show an up to 80% increase of power conversion efficiency (PCE) for short annealing periods at any of the mentioned temperatures. Together, this is in agreement with the expectations for enlargement of the interfacial area. However, for longer annealing times, a decrease of PCE is observed, despite the ongoing increase of interface roughness. The onset of decreasing PCE shifts to shorter durations the higher the annealing temperature. Both, X-ray reflectivity and device characteristics display a significant change at temperatures below the glass transition temperatures of P3HT and F8BT. PMID:26151720

  2. Design of a Catheter-Based Device for Performing Percutaneous Chordal-Cutting Procedures.

    PubMed

    Slocum, Alexander H; Bosworth, William R; Mazumdar, Anirban; Saez1, Miguel A; Culpepper, Martin L; Levine, Robert A

    2009-06-01

    This paper focuses on the design and implementation of a percutaneous catheter-based device to provide physicians with an externally controlled tool capable of manipulating and cutting specific chordae tendinae within the hear to alleviate problems associated with some forms of mitral valve regurgitationt. In the United States alone, approximately 500,000 people develop ischemic or functional MR per year, and the chordae tendinae cutting procedure and device are needed because many patients do not have the required level of health necessary to survive open-heart surgery. A deterministic design process was used to generate several design concepts and then evaluate and compare each concept based on a set of functional requirements. A final concept to be alpha prototyped was then chosen, further developed, and fabricated. Experiments showed that the design was capable of locating and grabbing a chord and that ultrasound imaging is a viable method for navigating the device inside of the human body. Once contact between the chord and an RF ablator tip was confirmed, the chord was successfully ablated. PMID:20352058

  3. Toward efficient aeroelastic energy harvesting: device performance comparisons and improvements through synchronized switching

    NASA Astrophysics Data System (ADS)

    Bryant, Matthew; Schlichting, Alexander D.; Garcia, Ephrahim

    2013-04-01

    This paper presents experimental energy harvesting efficiency analysis of a piezoelectric device driven to limit cycle oscillations by an aeroelastic flutter instability. Wind tunnel testing of the flutter energy harvester was used to measure the power extracted through a matched resistive load as well as the variation in the device swept area over a range of wind speeds. The efficiency of this energy harvester was shown to be maximized at a wind speed of about 2.4 m/s, which corresponds to a limit cycle oscillation (LCO) frequency that matches the first natural frequency of the piezoelectric structure. At this wind speed, the overall system efficiency was 2.6%, which exceeds the peak efficiency of other comparably sized oscillator-based wind energy harvesters using either piezoelectric or electromagnetic transduction. Active synchronized switching techniques are proposed as a method to further increase the overall efficiency of this device by both boosting the electrical output and also reducing the swept area by introducing additional electrical energy dissipation. Real-time peak detection and switch control is the major technical challenge to implementing such active power electronics schemes in a practical system where the wind speed and the corresponding LCO frequency are not generally known or constant. A promising microcontroller (MCU) based peak detector is implemented and tested over a range of operating wind speeds.

  4. Influence of composition on the performance of sintered Cu(In,Ga)Se2 nanocrystal thin-film photovoltaic devices.

    PubMed

    Akhavan, Vahid A; Harvey, Taylor B; Stolle, C Jackson; Ostrowski, David P; Glaz, Micah S; Goodfellow, Brian W; Panthani, Matthew G; Reid, Dariya K; Vanden Bout, David A; Korgel, Brian A

    2013-03-01

    Thin-film photovoltaic devices (PVs) were prepared by selenization using oleylamine-capped Cu(In,Ga)Se2 (CIGS) nanocrystals sintered at a high temperature (>500 °C) under Se vapor. The device performance varied significantly with [Ga]/[In+Ga] content in the nanocrystals. The highest power conversion efficiency (PCE) observed in the devices studied was 5.1 % under air mass 1.5 global (AM 1.5 G) illumination, obtained with [Ga]/[In+Ga]=0.32. The variation in PCE with composition is partly a result of bandgap tuning and optimization, but the main influence of nanocrystal composition appeared to be on the quality of the sintered films. The [Cu]/[In+Ga] content was found to be strongly influenced by the [Ga]/[In+Ga] concentration, which appears to be correlated with the morphology of the sintered film. For this reason, only small changes in the [Ga]/[In+Ga] content resulted in significant variations in device efficiency. PMID:23401465

  5. Numerical Simulation of the Performance Characteristics, Instability, and Effects of Band Gap Grading in Cadmium Telluride Based Photovoltaic Devices

    SciTech Connect

    Michael David Petersen

    2001-05-01

    Using computer simulations, the performance of several CdTe based photovoltaic structures has been studied. The advantages and disadvantages of band gap grading, through the use of (Zn,Cd)Te, have also been investigated in these structures. Grading at the front interface between a CdS window layer and a CdTe absorber layer, can arise due to interdiffusion between the materials during growth or due to the intentional variation of the material composition. This grading has been shown to improve certain performance metrics, such as the open-circuit voltage, while degrading others, such as the fill factor, depending on the amount and distance of the grading. The presence of a Schottky barrier as the back contact has also been shown to degrade the photovoltaic performance of the device, resulting in a characteristic IV curve. However, with the appropriate band gap grading at the back interface, it has been shown that the performance can be enhanced through more efficient carrier collection. These results were then correlated with experimental observations of the performance degradation in devices subjected to light and heat stress.

  6. Numerical Simulation of the Performance Characteristics, Instability, and Effects of Band Gap Grading in Cadmium Telluride Based Photovoltaic Devices

    SciTech Connect

    Michael David Petersen

    2001-06-27

    Using computer simulations, the performance of several CdTe based photovoltaic structures has been studied. The advantages and disadvantages of band gap grading, through the use of (Zn, Cd)Te, have also been investigated in these structures. Grading at the front interface between a CdS window layer and a CdTe absorber layer, can arise due to interdiffusion between the materials during growth or due to the intentional variation of the material composition. This grading has been shown to improve certain performance metrics, such as the open-circuit voltage, while degrading others, such as the fill factor, depending on the amount and distance of the grading. The presence of a Schottky barrier as the back contact has also been shown to degrade the photovoltaic performance of the device, resulting in a characteristic IV curve. However, with the appropriate band gap grading at the back interface, it has been shown that the performance can be enhanced through more efficient carrier collection. These results were then correlated with experimental observations of the performance degradation in devices subjected to light and heat stress.

  7. Performance evaluation tests of new laboratory procedures or devices: practical reporting criteria.

    PubMed

    Bridson, E

    1993-06-01

    The publication of papers reporting evaluations of new laboratory procedures and devices has increased rapidly in recent years. As more commercial systems emerge in the market place, and laboratory-based systems disappear, the potential user of the new system turns to his peers for opinions about the function of such systems. Unfortunately, many published reports lack statistical guidance and the reader is too often faced with a recitative about percentage differences and probabilities of significance, frequently reported on unacceptably small sample numbers. This communication offers guidance to those seeking to produce evaluation reports that will be of practical value to others. PMID:8219922

  8. Photovoltaic devices having nanoparticle dipoles for enhanced performance and methods for making same

    DOEpatents

    Williams, George M.; Schut, David M.; Stonas, Andreas

    2011-08-09

    A photovoltaic device has nanoparticles sandwiched between a conductive substrate and a charge selective transport layer. Each of the nanoparticles has a ligand shell attached to the nanoparticle core. A first type of ligand is electron rich and attached to one hemisphere of the nanoparticle core, while a second type of ligand is electron poor and attached to an opposite hemisphere of the core. Consequently, the ligand shell induces an electric field within the nanoparticle, enhancing the photovoltaic effect. The arrangement of ligands types on different sides of the nanoparticle is obtained by a process involving ligand substitution after adhering the nanoparticles to the conductive substrate.

  9. The Relationship between Affective Response to Social Comparison and Academic Performance in High School

    ERIC Educational Resources Information Center

    Wehrens, Maike J. P. W.; Buunk, Abraham P.; Lubbers, Miranda J.; Dijkstra, Pieternel; Kuyper, Hans; van der Werf, Greetje P. C.

    2010-01-01

    The goal of the present study was to study the relationship between affective responses to social comparison and test scores among high school students. Our analyses showed that three types of responses to social comparison could be distinguished: an empathic, constructive, and destructive response. Whereas girls scored higher on empathic…

  10. Nonmusic Majors' Cognitive and Affective Responses to Performance and Programmatic Music Videos.

    ERIC Educational Resources Information Center

    Geringer, John M.; Cassidy, Jane W.; Byo, James L.

    1997-01-01

    Compares the effects of different kinds of visual presentations, and music alone, on university nonmusic students' affective and cognitive responses to music. Separate groups of students listened to classical music excerpts, either by themselves, or with video accompaniment. They rated the music on Likert-type scales and responded to open-ended…

  11. Performance and Attitude of Student Teachers as Affected by Two Grading Systems

    ERIC Educational Resources Information Center

    Clawson, Barbara N.; Scruggs, M. Marguerite

    1974-01-01

    Findings of a study conducted at Iowa State University, Ames, indicated student subjects were not affected by the use of pass-fail grading, and that student teachers were less anxious and more positive about their relationship with their cooperating teachers under pass-fail than under A-F grading. (BP)

  12. The impact of tunnel oxide nitridation to reliability performance of charge storage non-volatile memory devices.

    PubMed

    Lee, Meng Chuan; Wong, Hin Yong

    2014-02-01

    This paper is written to review the development of critical research on the overall impact of tunnel oxide nitridation (TON) with the aim to mitigate reliability issues due to incessant technology scaling of charge storage NVM devices. For more than 30 years, charge storage non-volatile memory (NVM) has been critical in the evolution of intelligent electronic devices and continuous development of integrated technologies. Technology scaling is the primary strategy implemented throughout the semiconductor industry to increase NVM density and drive down average cost per bit. In this paper, critical reliability challenges and key innovative technical mitigation methods are reviewed. TON is one of the major candidates to replace conventional oxide layer for its superior quality and reliability performance. Major advantages and caveats of key TON process techniques are discussed. The impact of TON on quality and reliability performance of charge storage NVM devices is carefully reviewed with emphasis on major advantages and drawbacks of top and bottom nitridation. Physical mechanisms attributed to charge retention and V(t) instability phenomenon are also reviewed in this paper. PMID:24749438

  13. Spray-painted binder-free SnSe electrodes for high-performance energy-storage devices.

    PubMed

    Wang, Xianfu; Liu, Bin; Xiang, Qingyi; Wang, Qiufan; Hou, Xiaojuan; Chen, Di; Shen, Guozhen

    2014-01-01

    SnSe nanocrystal electrodes on three-dimensional (3D) carbon fabric and Au-coated polyethylene terephthalate (PET) wafer have been prepared by a simple spray-painting process and were further investigated as binder-free active-electrodes for Lithium-ion batteries (LIBs) and flexible stacked all-solid-state supercapacitors. The as-painted SnSe nanocrystals/carbon fabric electrodes exhibit an outstanding capacity of 676 mAh g(-1) after 80 cycles at a current density of 200 mA g(-1) and a considerable high-rate capability in lithium storage because of the excellent ion transport from the electrolyte to the active materials and the efficient charge transport between current collector and electrode materials. The binder-free electrodes also provide a larger electrochemical active surface compared with electrodes containing binders, which leads to the enhanced capacities of energy-storage devices. A flexible stacked all-solid-state supercapacitor based on the SnSe nanocrystals on Au-coated PET wafers shows high capacitance reversibility with little performance degradation at different current densities after 2200 charge-discharge cycles and even when bent. This allows for many potential applications in facile, cost-effective, spray-paintable, and flexible energy-storage devices. The results indicate that the fabrication of binder-free electrodes by a spray painting process is an interesting direction for the preparation of high-performance energy-storage devices. PMID:24339208

  14. Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

    NASA Technical Reports Server (NTRS)

    Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

    2012-01-01

    A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

  15. Cognition-based and affect-based trust as mediators of leader behavior influences on team performance.

    PubMed

    Schaubroeck, John; Lam, Simon S K; Peng, Ann Chunyan

    2011-07-01

    We develop a model in which cognitive and affective trust in the leader mediate the relationship between leader behavior and team psychological states that, in turn, drive team performance. The model is tested on a sample of 191 financial services teams in Hong Kong and the U.S. Servant leadership influenced team performance through affect-based trust and team psychological safety. Transformational leadership influenced team performance indirectly through cognition-based trust. Cognition-based trust directly influenced team potency and indirectly (through affect-based trust) influenced team psychological safety. The effects of leader behavior on team performance were fully mediated through the trust in leader variables and the team psychological states. Servant leadership explained an additional 10% of the variance in team performance beyond the effect of transformational leadership. We discuss implications of these results for research on the relationship between leader behavior and team performance, and for efforts to enhance leader development by combining knowledge from different leadership theories. PMID:21299271

  16. Do candidate reactions relate to job performance or affect criterion-related validity? A multistudy investigation of relations among reactions, selection test scores, and job performance.

    PubMed

    McCarthy, Julie M; Van Iddekinge, Chad H; Lievens, Filip; Kung, Mei-Chuan; Sinar, Evan F; Campion, Michael A

    2013-09-01

    Considerable evidence suggests that how candidates react to selection procedures can affect their test performance and their attitudes toward the hiring organization (e.g., recommending the firm to others). However, very few studies of candidate reactions have examined one of the outcomes organizations care most about: job performance. We attempt to address this gap by developing and testing a conceptual framework that delineates whether and how candidate reactions might influence job performance. We accomplish this objective using data from 4 studies (total N = 6,480), 6 selection procedures (personality tests, job knowledge tests, cognitive ability tests, work samples, situational judgment tests, and a selection inventory), 5 key candidate reactions (anxiety, motivation, belief in tests, self-efficacy, and procedural justice), 2 contexts (industry and education), 3 continents (North America, South America, and Europe), 2 study designs (predictive and concurrent), and 4 occupational areas (medical, sales, customer service, and technological). Consistent with previous research, candidate reactions were related to test scores, and test scores were related to job performance. Further, there was some evidence that reactions affected performance indirectly through their influence on test scores. Finally, in no cases did candidate reactions affect the prediction of job performance by increasing or decreasing the criterion-related validity of test scores. Implications of these findings and avenues for future research are discussed. PMID:23937298

  17. To What Degree Does Provider Performance Affect a Quality Indicator? The Case of Nursing Homes and ADL Change

    ERIC Educational Resources Information Center

    Phillips, Charles D.; Chen, Min; Sherman, Michael

    2008-01-01

    Purpose: This research investigates what factors affect the degree to which nursing home performance explains variance in residents' change in status of activities of daily living (ADL) after admission. Design and Methods: The database included all residents admitted in 2002 to a 10% random sample of nursing homes in the United States.…

  18. Determining the Factors That Affect the Objectives of Pre-Service Science Teachers to Perform Outdoor Science Activities

    ERIC Educational Resources Information Center

    Karademir, Ersin; Erten, Sinan

    2013-01-01

    The purpose of this study is to determine whether pre-service teachers have an aim to perform outdoor education activities within the scope of science and technology course; by which factors this aim is affected, through The Theory of Planned Behaviour and the opinions of pre-service teachers. Accordingly, the study was designed as mixed research…

  19. Effects of musical tempo on physiological, affective, and perceptual variables and performance of self-selected walking pace

    PubMed Central

    Almeida, Flávia Angélica Martins; Nunes, Renan Felipe Hartmann; Ferreira, Sandro dos Santos; Krinski, Kleverton; Elsangedy, Hassan Mohamed; Buzzachera, Cosme Franklin; Alves, Ragami Chaves; Gregorio da Silva, Sergio

    2015-01-01

    [Purpose] This study investigated the effects of musical tempo on physiological, affective, and perceptual responses as well as the performance of self-selected walking pace. [Subjects] The study included 28 adult women between 29 and 51 years old. [Methods] The subjects were divided into three groups: no musical stimulation group (control), and 90 and 140 beats per minute musical tempo groups. Each subject underwent three experimental sessions: involved familiarization with the equipment, an incremental test to exhaustion, and a 30-min walk on a treadmill at a self-selected pace, respectively. During the self-selected walking session, physiological, perceptual, and affective variables were evaluated, and walking performance was evaluated at the end. [Results] There were no significant differences in physiological variables or affective response among groups. However, there were significant differences in perceptual response and walking performance among groups. [Conclusion] Fast music (140 beats per minute) promotes a higher rating of perceived exertion and greater performance in self-selected walking pace without significantly altering physiological variables or affective response. PMID:26180303

  20. Teacher Discourse and Sixth Graders' Reported Affect and Achievement Behaviors in Two High-Mastery/High-Performance Mathematics Classrooms.

    ERIC Educational Resources Information Center

    Turner, Julianne C.; Meyer, Debra K.; Midgley, Carol; Patrick, Helen

    2003-01-01

    Examined the relation between the nature of teacher discourse and sixth-grade students' reports of affect and behavior in mathematics classrooms students perceived as emphasizing both mastery and performance goals. Found that students in the classroom in which there was constant and explicit support for autonomy and intrinsic motivation, positive…