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Sample records for high mobility barriers

  1. High mobility two-dimensional electron gases in nitride heterostructures with high Al composition AlGaN alloy barriers

    Li Guowang; Cao Yu; Xing Huili Grace; Jena, Debdeep

    2010-01-01

    We report high-electron mobility nitride heterostructures with >70% Al composition AlGaN alloy barriers grown by molecular beam epitaxy. Direct growth of such AlGaN layers on GaN resulted in hexagonal trenches and a low mobility polarization-induced charge. By applying growth interruption at the heterojunction, the surface morphology improved dramatically and the room temperature two-dimensional electron gas (2DEG) mobility increased by an order of magnitude, exceeding 1300 cm 2 /V s. The 2DEG density was tunable at 0.4-3.7x10 13 /cm 2 by varying the total barrier thickness (t). Surface barrier heights of the heterostructures were extracted and exhibited dependence on t.

  2. Group-III nitride based high electron mobility transistor (HEMT) with barrier/spacer layer

    Chavarkar, Prashant; Smorchkova, Ioulia P.; Keller, Stacia; Mishra, Umesh; Walukiewicz, Wladyslaw; Wu, Yifeng

    2005-02-01

    A Group III nitride based high electron mobility transistors (HEMT) is disclosed that provides improved high frequency performance. One embodiment of the HEMT comprises a GaN buffer layer, with an Al.sub.y Ga.sub.1-y N (y=1 or y 1) layer on the GaN buffer layer. An Al.sub.x Ga.sub.1-x N (0.ltoreq.x.ltoreq.0.5) barrier layer on to the Al.sub.y Ga.sub.1-y N layer, opposite the GaN buffer layer, Al.sub.y Ga.sub.1-y N layer having a higher Al concentration than that of the Al.sub.x Ga.sub.1-x N barrier layer. A preferred Al.sub.y Ga.sub.1-y N layer has y=1 or y.about.1 and a preferred Al.sub.x Ga.sub.1-x N barrier layer has 0.ltoreq.x.ltoreq.0.5. A 2DEG forms at the interface between the GaN buffer layer and the Al.sub.y Ga.sub.1-y N layer. Respective source, drain and gate contacts are formed on the Al.sub.x Ga.sub.1-x N barrier layer. The HEMT can also comprising a substrate adjacent to the buffer layer, opposite the Al.sub.y Ga.sub.1-y N layer and a nucleation layer between the Al.sub.x Ga.sub.1-x N buffer layer and the substrate.

  3. Plasma-assisted Molecular Beam Epitaxy of N-polar InAlN-barrier High-electron-mobility Transistors.

    Hardy, Matthew T; Storm, David F; Katzer, D Scott; Downey, Brian P; Nepal, Neeraj; Meyer, David J

    2016-11-24

    Plasma-assisted molecular beam epitaxy is well suited for the epitaxial growth of III-nitride thin films and heterostructures with smooth, abrupt interfaces required for high-quality high-electron-mobility transistors (HEMTs). A procedure is presented for the growth of N-polar InAlN HEMTs, including wafer preparation and growth of buffer layers, the InAlN barrier layer, AlN and GaN interlayers and the GaN channel. Critical issues at each step of the process are identified, such as avoiding Ga accumulation in the GaN buffer, the role of temperature on InAlN compositional homogeneity, and the use of Ga flux during the AlN interlayer and the interrupt prior to GaN channel growth. Compositionally homogeneous N-polar InAlN thin films are demonstrated with surface root-mean-squared roughness as low as 0.19 nm and InAlN-based HEMT structures are reported having mobility as high as 1,750 cm 2 /V∙sec for devices with a sheet charge density of 1.7 x 10 13 cm -2 .

  4. Impact of barrier thickness on transistor performance in AlN/GaN high electron mobility transistors grown on free-standing GaN substrates

    Deen, David A.; Storm, David F.; Meyer, David J.; Bass, Robert; Binari, Steven C.; Gougousi, Theodosia; Evans, Keith R.

    2014-01-01

    A series of six ultrathin AlN/GaN heterostructures with varied AlN thicknesses from 1.5–6 nm have been grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. High electron mobility transistors (HEMTs) were fabricated from the set in order to assess the impact of barrier thickness and homo-epitaxial growth on transistor performance. Room temperature Hall characteristics revealed mobility of 1700 cm 2 /V s and sheet resistance of 130 Ω/□ for a 3 nm thick barrier, ranking amongst the lowest room-temperature sheet resistance values reported for a polarization-doped single heterostructure in the III-Nitride family. DC and small signal HEMT electrical characteristics from submicron gate length HEMTs further elucidated the effect of the AlN barrier thickness on device performance.

  5. Impact of barrier thickness on transistor performance in AlN/GaN high electron mobility transistors grown on free-standing GaN substrates

    Deen, David A., E-mail: david.deen@alumni.nd.edu; Storm, David F.; Meyer, David J.; Bass, Robert; Binari, Steven C. [Electronics Science and Technology Division, Naval Research Laboratory, Washington, DC 20375-5347 (United States); Gougousi, Theodosia [Physics Department, University of Maryland Baltimore County, Baltimore, Maryland 21250 (United States); Evans, Keith R. [Kyma Technologies, Raleigh, North Carolina 27617 (United States)

    2014-09-01

    A series of six ultrathin AlN/GaN heterostructures with varied AlN thicknesses from 1.5–6 nm have been grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. High electron mobility transistors (HEMTs) were fabricated from the set in order to assess the impact of barrier thickness and homo-epitaxial growth on transistor performance. Room temperature Hall characteristics revealed mobility of 1700 cm{sup 2}/V s and sheet resistance of 130 Ω/□ for a 3 nm thick barrier, ranking amongst the lowest room-temperature sheet resistance values reported for a polarization-doped single heterostructure in the III-Nitride family. DC and small signal HEMT electrical characteristics from submicron gate length HEMTs further elucidated the effect of the AlN barrier thickness on device performance.

  6. Dielectric and barrier thickness fluctuation scattering in Al2O3/AlGaN/GaN double heterojunction high-electron mobility transistors

    Ji, Dong; Lu, Yanwu; Liu, Bing; Liu, Guipeng; Zhu, Qinsheng; Wang, Zhanguo

    2013-01-01

    The two-dimensional electron gas (2DEG) mobility limited by dielectric and barrier thickness fluctuations (TF) scattering in Al 2 O 3 /AlGaN/GaN double heterojunction high-electron mobility transistors (HEMTs) is calculated. Calculation shows that thickness fluctuation scattering is the main limitation in Al 2 O 3 /AlGaN/GaN double heterojunction HEMTs with thin Al 2 O 3 layer thicknesses. In addition, a study of 2DEG mobility as a function of 2DEG density, n s , shows that TF scattering acts as the main limitation when n s exceeds 2 × 10 12 cm −2 . The results may be used to design HEMTs to obtain higher 2DEG mobilities by modulating the dielectric layer and barrier thicknesses or 2DEG density. - Highlights: • The mobility limited by thickness fluctuation (TF) scattering is studied. • Results show that thickness fluctuation scattering is the main limitation. • Two-dimensional electron gas (2DEG) mobility is a function of 2DEG density. • TF scattering is the main limitation when 2DEG density exceeds 2 × 10 12 cm −2

  7. Simulation study of InAlN/GaN high-electron mobility transistor with AlInN back barrier

    Han Tie-Cheng; Zhao Hong-Dong; Yang Lei; Wang Yang

    2017-01-01

    In this work, we use a 3-nm-thick Al 0.64 In 0.36 N back-barrier layer in In 0.17 Al 0.83 N/GaN high-electron mobility transistor (HEMT) to enhance electron confinement. Based on two-dimensional device simulations, the influences of Al 0.64 In 0.36 N back-barrier on the direct-current (DC) and radio-frequency (RF) characteristics of InAlN/GaN HEMT are investigated, theoretically. It is shown that an effective conduction band discontinuity of approximately 0.5 eV is created by the 3-nm-thick Al 0.64 In 0.36 N back-barrier and no parasitic electron channel is formed. Comparing with the conventional InAlN/GaN HEMT, the electron confinement of the back-barrier HEMT is significantly improved, which allows a good immunity to short-channel effect (SCE) for gate length decreasing down to 60 nm (9-nm top barrier). For a 70-nm gate length, the peak current gain cut-off frequency ( f T ) and power gain cut-off frequency ( f max ) of the back-barrier HEMT are 172 GHz and 217 GHz, respectively, which are higher than those of the conventional HEMT with the same gate length. (paper)

  8. Investigation of the current collapse induced in InGaN back barrier AlGaN/GaN high electron mobility transistors

    Wan Xiaojia; Wang Xiaoliang; Xiao Hongling; Feng Chun; Jiang Lijuan; Qu Shenqi; Wang Zhanguo; Hou Xun

    2013-01-01

    Current collapses were studied, which were observed in AlGaN/GaN high electron mobility transistors (HEMTs) with and without InGaN back barrier (BB) as a result of short-term bias stress. More serious drain current collapses were observed in InGaN BB AlGaN/GaN HEMTs compared with the traditional HEMTs. The results indicate that the defects and surface states induced by the InGaN BB layer may enhance the current collapse. The surface states may be the primary mechanism of the origination of current collapse in AlGaN/GaN HEMTs for short-term direct current stress. (semiconductor devices)

  9. Consumer Mobile Health Apps: Current State, Barriers, and Future Directions.

    Kao, Cheng-Kai; Liebovitz, David M

    2017-05-01

    This paper discusses the current state, barriers, and future directions of consumer-facing applications (apps). There are currently more than 165,000 mobile health apps publicly available in major app stores, the vast majority of which are designed for patients. The top 2 categories are wellness management and disease management apps, whereas other categories include self-diagnosis, medication reminder, and electronic patient portal apps. Apps specific to physical medicine and rehabilitation also are reviewed. These apps have the potential to provide low-cost, around-the-clock access to high-quality, evidence-based health information to end users on a global scale. However, they have not yet lived up to their potential due to multiple barriers, including lack of regulatory oversight, limited evidence-based literature, and concerns of privacy and security. The future directions may consist of improving data integration into the health care system, an interoperable app platform allowing access to electronic health record data, cloud-based personal health record across health care networks, and increasing app prescription by health care providers. For consumer mobile health apps to fully contribute value to health care delivery and chronic disease management, all stakeholders within the ecosystem must collaborate to overcome the significant barriers. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

  10. Barriers to International Student Mobility: Evidence from the Erasmus Program

    Souto-Otero, Manuel; Huisman, Jeroen; Beerkens, Maarja; de Wit, Hans; Vujic, Suncica

    2013-01-01

    In this article, we look at the barriers to international student mobility, with particular reference to the European Erasmus program. Much is known about factors that support or limit student mobility, but very few studies have made comparisons between participants and nonparticipants. Making use of a large data set on Erasmus and non-Erasmus…

  11. Barriers and Facilitators to Community Mobility for Assistive Technology Users

    Natasha Layton

    2012-01-01

    Full Text Available Mobility is frequently described in terms of individual body function and structures however contemporary views of disability also recognise the role of environment in creating disability. Aim. To identify consumer perspectives regarding barriers and facilitators to optimal mobility for a heterogeneous population of impaired Victorians who use assistive technology in their daily lives. Method. An accessible survey investigated the impact of supports or facilitators upon actual and desired life outcomes and health-related quality of life, from 100 AT users in Victoria, Australia. This paper reports upon data pertaining to community mobility. Results. A range of barriers and enablers to community mobility were identified including access to AT devices, environmental interventions, public transport, and inclusive community environs. Substantial levels of unmet need result in limited personal mobility and community participation. Outcomes fall short of many principles enshrined in current policy and human rights frameworks. Conclusion. AT devices as well as accessible and inclusive home and community environs are essential to maximizing mobility for many. Given the impact of the environment upon the capacity of individuals to realise community mobility, this raises the question as to whether rehabilitation practitioners, as well as prescribing AT devices, should work to build accessible communities via systemic advocacy.

  12. 1.5-V-threshold-voltage Schottky barrier normally-off AlGaN/GaN high-electron-mobility transistors with f T/f max of 41/125 GHz

    Hou, Bin; Ma, Xiaohua; Yang, Ling; Zhu, Jiejie; Zhu, Qing; Chen, Lixiang; Mi, Minhan; Zhang, Hengshuang; Zhang, Meng; Zhang, Peng; Zhou, Xiaowei; Hao, Yue

    2017-07-01

    In this paper, a normally-off AlGaN/GaN high-electron-mobility transistors (HEMT) fabricated using inductively coupled plasma (ICP) CF4 plasma recessing and an implantation technique is reported. A gate-to-channel distance of ˜10 nm and an equivalent negative fluorine sheet charge density of -1.21 × 1013 cm-2 extracted using a simple threshold voltage (V th) analytical model result in a high V th of 1.5 V, a peak transconductance of 356 mS/mm, and a subthreshold slope of 133 mV/decade. A small degradation of channel mobility leads to a high RF performance with f T/f max of 41/125 GHz, resulting in a record high f T × L g product of 10.66 GHz·µm among Schottky barrier AlGaN/GaN normally-off HEMTs with V th exceeding 1 V, to the best of our knowledge.

  13. Older adults' attitudes and barriers toward the use of mobile phones.

    Navabi, Nasrin; Ghaffari, Fatemeh; Jannat-Alipoor, Zahra

    2016-01-01

    The limitations caused by the process of aging and the prevalence of chronic diseases contribute to reduced performance in physical, psychological, and social areas of life in older people. The use of mobile phones as easily accessible portable tools with a high performance is associated with an increased health literacy, self-care, and independence in older people. The present study was conducted to determine older people's attitudes toward the use of mobile phones and the barriers to their use. The present descriptive study was conducted on a sample population of 328 individuals older than 60 years presenting to health centers across cities in west Mazandaran, Iran. The data collection tools used included a mobile phone use checklist, a questionnaire on older people's attitude toward the use of mobile phones, and a questionnaire on the barriers to the use of mobile phones. The reliability and validity of these questionnaires were confirmed by the researchers. The data obtained were recorded and then analyzed using SPSS. The level of statistical significance was set at P ≤0.05. According to the results, 80% of the older people had regular mobile phones and 20% had smartphones. In 95% of the male and 80% of the female participants, the greatest use of mobile phones pertained to making phone calls. A total of 5% of the male and 2% of the female participants used the Internet in their mobile phones. A total of 44% of the female and 42.80% of the male participants had poor attitudes (score from 0 to 40) toward mobile phone use. As for the different dimensions of the attitude toward mobile phone use, the highest score obtained by the female participants (71.66%) pertained to the psychoemotional dimension and the highest score in the male participants (72.85%) to the instrumental dimension. The results also revealed the lack of knowledge of English as the greatest barrier to mobile phone use in both sexes. There was a significant relationship between sex and the

  14. High mobility emissive organic semiconductor

    Liu, Jie; Zhang, Hantang; Dong, Huanli; Meng, Lingqiang; Jiang, Longfeng; Jiang, Lang; Wang, Ying; Yu, Junsheng; Sun, Yanming; Hu, Wenping; Heeger, Alan J.

    2015-01-01

    The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm2 V−1 s−1. Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m−2 and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics. PMID:26620323

  15. Older adults’ attitudes and barriers toward the use of mobile phones

    Navabi N

    2016-09-01

    Full Text Available Nasrin Navabi, Fatemeh Ghaffari, Zahra Jannat-Alipoor Nursing and Midwifery Department, Babol University of Medical Sciences, Mazandaran, Iran Background and objectives: The limitations caused by the process of aging and the prevalence of chronic diseases contribute to reduced performance in physical, psychological, and social areas of life in older people. The use of mobile phones as easily accessible portable tools with a high performance is associated with an increased health literacy, self-care, and independence in older people. The present study was conducted to determine older people’s attitudes toward the use of mobile phones and the barriers to their use. Materials and methods: The present descriptive study was conducted on a sample population of 328 individuals older than 60 years presenting to health centers across cities in west Mazandaran, Iran. The data collection tools used included a mobile phone use checklist, a questionnaire on older people’s attitude toward the use of mobile phones, and a questionnaire on the barriers to the use of mobile phones. The reliability and validity of these questionnaires were confirmed by the researchers. The data obtained were recorded and then analyzed using SPSS. The level of statistical significance was set at P≤0.05. Results: According to the results, 80% of the older people had regular mobile phones and 20% had smartphones. In 95% of the male and 80% of the female participants, the greatest use of mobile phones pertained to making phone calls. A total of 5% of the male and 2% of the female participants used the Internet in their mobile phones. A total of 44% of the female and 42.80% of the male participants had poor attitudes (score from 0 to 40 toward mobile phone use. As for the different dimensions of the attitude toward mobile phone use, the highest score obtained by the female participants (71.66% pertained to the psychoemotional dimension and the highest score in the male

  16. Mobile Learning in Nursing Undergraduates in China: Current Status, Attitudes and Barriers.

    Xiao, Qian; Zhang, Qiannan; Wang, Lanlan; Wang, Yanling; Sun, Liu; Wu, Ying

    2017-01-01

    To explore the current status, attitudes and barriers of nursing undergraduates toward mobile learning, 157 nursing students were investigated. more than half of them used mobile learning frequently in past half year. The mean score of students' intention towards mobile learning was 10.5 (ranged from 6 to 15), and it related to students' gender, expected effect, ease of operation, influence of other students, self-learning management and perceived interest. Some barriers affected students' mobile learning. Therefore, students had positive attitude and perception toward mobile learning, then we should create enough conditions to promote students' mobile learning.

  17. Unfractionated Heparin Alleviates Human Lung Endothelial Barrier Dysfunction Induced by High Mobility Group Box 1 Through Regulation of P38–GSK3β–Snail Signaling Pathway

    Zhenggang Luan

    2018-04-01

    Full Text Available Background/Aims: The high mobility group box 1 (HMGB1 has been regarded as an important inflammatory mediator. Previous studies showed the involvement of HMGB1 protein in the dysfunction of endothelial barrier function during acute lung injury. However, the molecular mechanism remains unclear. Methods: In this study, we used recombinant human HMGB1 (rhHMGB1 and HMGB1 plasmid to treat human pulmonary microvascular endothelial cell (HPMECs. We examined endothelial permeability by measuring TEER value and HRP flux. Western blot and real-time PCR were used to examined change of endothelial-to-mesenchymal transition (EndoMT markers and related pathways. Immunofluorescence was used to examine localization and expression of ZO-1 and VE-cadherin. SB203580.was used to block p38 pathway. Unfractionated heparin (UFH and RAGE siRNA were also used to antagonize the effect of HMGB1. Results: We showed that HMGB1 induced EndoMT with downregulation of ZO-1 and VE-cadherin at both mRNA and protein levels in HPMECs. We also demonstrated that HMGB1 upregulated endothelial permeability by measuring TEER value and HRP flux. Moreover, HMGB1 activated p38/GSK3β/Snail signaling pathway and treatment with p38 inhibitor SB203580 abolished its biological effects. In addition, we found that UFH was able to reverse the effect of HMGB1 on EndoMT and endothelial permeability through inhibition of p38 signaling in a dose-dependent manner. We discovered that RAGE, a membrane receptor of HMGB1, transduced p38/Snail pathway to EndoMT. RAGE siRNA inhibited the effect of HMGB1 induced EndoMT in HPMECs. Conclusion: The present study demonstrated that HMGB1 induced EndoMT through RAGE receptor and p38/GSK3β/Snail pathway. While UFH antagonized HMGB1 and maintained the integrity of the endothelial barrier through p38 inhibition.

  18. Fixed interface charges between AlGaN barrier and gate stack composed of in situ grown SiN and Al2O3 in AlGaN/GaN high electron mobility transistors with normally off capability

    Capriotti, M.; Alexewicz, A.; Fleury, C.; Gavagnin, M.; Bethge, O.; Wanzenböck, H. D.; Bertagnolli, E.; Pogany, D.; Strasser, G.; Visalli, D.; Derluyn, J.

    2014-01-01

    Using a generalized extraction method, the fixed charge density N int at the interface between in situ deposited SiN and 5 nm thick AlGaN barrier is evaluated by measurements of threshold voltage V th of an AlGaN/GaN metal insulator semiconductor high electron mobility transistor as a function of SiN thickness. The thickness of the originally deposited 50 nm thick SiN layer is reduced by dry etching. The extracted N int is in the order of the AlGaN polarization charge density. The total removal of the in situ SiN cap leads to a complete depletion of the channel region resulting in V th  = +1 V. Fabrication of a gate stack with Al 2 O 3 as a second cap layer, deposited on top of the in situ SiN, is not introducing additional fixed charges at the SiN/Al 2 O 3 interface

  19. Ion mobility and transport barriers in the tokamak plasmas

    Xiao, H.; Hazeltine, R.D.; Valanju, P.M.

    1993-06-01

    The character of charged particle motion in an axisymmetric toroidal system with a constant radial electric field is investigated both analytically and numerically. Ion radial mobility caused by the combined effects of the radial electric field and charge exchange is found. A simple moment argument in the banana regime matches the simulation results well. Relation of present work and high confinement (H-mode) experiment is also discussed

  20. Older adults’ attitudes and barriers toward the use of mobile phones

    Navabi, Nasrin; Ghaffari, Fatemeh; Jannat-Alipoor, Zahra

    2016-01-01

    Background and objectives The limitations caused by the process of aging and the prevalence of chronic diseases contribute to reduced performance in physical, psychological, and social areas of life in older people. The use of mobile phones as easily accessible portable tools with a high performance is associated with an increased health literacy, self-care, and independence in older people. The present study was conducted to determine older people’s attitudes toward the use of mobile phones and the barriers to their use. Materials and methods The present descriptive study was conducted on a sample population of 328 individuals older than 60 years presenting to health centers across cities in west Mazandaran, Iran. The data collection tools used included a mobile phone use checklist, a questionnaire on older people’s attitude toward the use of mobile phones, and a questionnaire on the barriers to the use of mobile phones. The reliability and validity of these questionnaires were confirmed by the researchers. The data obtained were recorded and then analyzed using SPSS. The level of statistical significance was set at P≤0.05. Results According to the results, 80% of the older people had regular mobile phones and 20% had smartphones. In 95% of the male and 80% of the female participants, the greatest use of mobile phones pertained to making phone calls. A total of 5% of the male and 2% of the female participants used the Internet in their mobile phones. A total of 44% of the female and 42.80% of the male participants had poor attitudes (score from 0 to 40) toward mobile phone use. As for the different dimensions of the attitude toward mobile phone use, the highest score obtained by the female participants (71.66%) pertained to the psychoemotional dimension and the highest score in the male participants (72.85%) to the instrumental dimension. The results also revealed the lack of knowledge of English as the greatest barrier to mobile phone use in both sexes

  1. Modeling small-signal response of GaN-based metal-insulator-semiconductor high electron mobility transistor gate stack in spill-over regime: Effect of barrier resistance and interface states

    Capriotti, M.; Fleury, C.; Oposich, M.; Bethge, O.; Strasser, G.; Pogany, D.; Lagger, P.; Ostermaier, C.

    2015-01-01

    We provide theoretical and simulation analysis of the small signal response of SiO 2 /AlGaN/GaN metal insulator semiconductor (MIS) capacitors from depletion to spill over region, where the AlGaN/SiO 2 interface is accumulated with free electrons. A lumped element model of the gate stack, including the response of traps at the III-N/dielectric interface, is proposed and represented in terms of equivalent parallel capacitance, C p , and conductance, G p . C p -voltage and G p -voltage dependences are modelled taking into account bias dependent AlGaN barrier dynamic resistance R br and the effective channel resistance. In particular, in the spill-over region, the drop of C p with the frequency increase can be explained even without taking into account the response of interface traps, solely by considering the intrinsic response of the gate stack (i.e., no trap effects) and the decrease of R br with the applied forward bias. Furthermore, we show the limitations of the conductance method for the evaluation of the density of interface traps, D it , from the G p /ω vs. angular frequency ω curves. A peak in G p /ω vs. ω occurs even without traps, merely due to the intrinsic frequency response of gate stack. Moreover, the amplitude of the G p /ω vs. ω peak saturates at high D it , which can lead to underestimation of D it . Understanding the complex interplay between the intrinsic gate stack response and the effect of interface traps is relevant for the development of normally on and normally off MIS high electron mobility transistors with stable threshold voltage

  2. Managers' experience of success criteria and barriers to implementing mobile radiography services in nursing homes in Norway: a qualitative study.

    Kjelle, Elin; Lysdahl, Kristin Bakke; Olerud, Hilde Merete; Myklebust, Aud Mette

    2018-04-25

    In order to meet the future challenges posed by ageing populations, new technology, telemedicine and a more personalized healthcare system are needed. Earlier research has shown mobile radiography services to be highly beneficial for nursing home residents in addition to being cost-effective. Despite the benefits, mobile radiography services are uncommon in Europe and Norway. The purpose of this study was to explore success criteria and barriers in the process of implementing mobile radiography services, from the point of view of the hospital and municipal managers. Eleven semi-structured interviews were conducted with managers from five hospitals and six municipalities in Norway where mobile radiography services had been implemented. Core issues in the interview guide were barriers and facilitators in the different phases of implementation. The framework method for thematic analysis was used for analysing the data inductively in a research team. Five main categories were developed through the success criteria and barriers experienced by the participants: national health policy, regional and municipal policy and conditions, inter-organizational implementation projects, experienced outcome, and professional skills and personal characteristics. The categories were allocated into three higher-order classifications: macro, meso and micro levels. The main barriers experienced by the managers were financial, procedural and structural. In particular, the reimbursement system, lack of management across healthcare levels and the lack of compatible information systems acted as barriers. The main facilitators were external funding, enthusiastic individuals in the organizations and good collaboration between hospitals and municipalities. The managers experienced financial, structural and procedural barriers. The main success criteria in the process were external funding, and the support and engagement from the individuals in the organizations. This commitment was mainly

  3. Barriers and facilitators to mobile phone use for people with aphasia.

    Greig, Carole-Ann; Harper, Renée; Hirst, Tanya; Howe, Tami; Davidson, Bronwyn

    2008-01-01

    Mobile phone use increases social participation. People with the communication disorder of aphasia are disadvantaged in the use of information and communication technology such as mobile phones and are reported to be more socially isolated than their peers. The World Health Organization's International Classification of Functioning, Disability and Health provides a framework to address the impact of environmental factors on individual participation. The aim of this preliminary study was to identify the barriers and facilitators to mobile phone use for people with aphasia. A qualitative descriptive study involving two phases was conducted: (1) semi-structured interviews with 6 individuals with aphasia who owned or expressed a desire to own a mobile phone; (2) structured observations of key scenarios identified in the interviews of 3 participants who were sampled from the interview study. Results identified 18 barriers and 9 facilitators to mobile phone use. Key barriers and facilitators were identified in the areas of design and features, written support and training, and communicative partners. Mobile phone use can be problematic for people with aphasia. Intervention needs to address the barriers and utilise the facilitators to mobile phone use for this population. Further research is required to inform policy and intervention programs to ensure that people with aphasia have access to this technology.

  4. High electron mobility InN

    Jones, R. E.; Li, S. X.; Haller, E. E.; van Genuchten, H. C. M.; Yu, K. M.; Ager, J. W. III; Liliental-Weber, Z.; Walukiewicz, W.; Lu, H.; Schaff, W. J.

    2007-01-01

    Irradiation of InN films with 2 MeV He + ions followed by thermal annealing below 500 deg. C creates films with high electron concentrations and mobilities, as well as strong photoluminescence. Calculations show that electron mobility in irradiated samples is limited by triply charged donor defects. Subsequent thermal annealing removes a fraction of the defects, decreasing the electron concentration. There is a large increase in electron mobility upon annealing; the mobilities approach those of the as-grown films, which have 10 to 100 times smaller electron concentrations. Spatial ordering of the triply charged defects is suggested to cause the unusual increase in electron mobility

  5. Artificial barriers prevent genetic recovery of small isolated populations of a low-mobility freshwater fish.

    Coleman, R A; Gauffre, B; Pavlova, A; Beheregaray, L B; Kearns, J; Lyon, J; Sasaki, M; Leblois, R; Sgro, C; Sunnucks, P

    2018-01-12

    Habitat loss and fragmentation often result in small, isolated populations vulnerable to environmental disturbance and loss of genetic diversity. Low genetic diversity can increase extinction risk of small populations by elevating inbreeding and inbreeding depression, and reducing adaptive potential. Due to their linear nature and extensive use by humans, freshwater ecosystems are especially vulnerable to habitat loss and fragmentation. Although the effects of fragmentation on genetic structure have been extensively studied in migratory fishes, they are less understood in low-mobility species. We estimated impacts of instream barriers on genetic structure and diversity of the low-mobility river blackfish (Gadopsis marmoratus) within five streams separated by weirs or dams constructed 45-120 years ago. We found evidence of small-scale (barriers, as expected for a fish with low mobility. Genetic diversity was lower above barriers in small streams only, regardless of barrier age. In particular, one isolated population showed evidence of a recent bottleneck and inbreeding. Differentiation above and below the barrier (F ST  = 0.13) was greatest in this stream, but in other streams did not differ from background levels. Spatially explicit simulations suggest that short-term barrier effects would not be detected with our data set unless effective population sizes were very small (barriers is reduced and requires more genetic markers compared to panmictic populations. We also demonstrate the importance of accounting for natural population genetic structure in fragmentation studies.

  6. High speed PVD thermal barrier coatings

    Beele, W. [Sulzer Metco Coatings BV (Netherlands); Eschendorff, G. [Sulzer Metco Coatings BV (Netherlands); Eldim BV (Netherlands)

    2006-07-15

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  7. High speed PVD thermal barrier coatings

    Beele, W.; Eschendorff, G.

    2006-01-01

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. [Mobile IT: Possibilities and barriers of mHealth].

    Böckmann, B

    2016-04-01

    The increasing availability of mobile devices and corresponding applications, both for providers and patients, often leads to speculation that mHealth, as the combination of mobile devices and health services is often called, would revolutionize the use of information technology (IT) in healthcare. On the other hand users, providers and operators providing such solutions are often confronted with completely new challenges. This article assesses the options and potential of mHealth and also takes a critical look at potential obstacles. As this field is very broad this critical analysis is illustrated by means of three exemplary application areas: mHealth in radiology, the influence of mHealth on research and mHealth as an enabler of new services, always with examples from other countries.The use of mHealth in radiology currently often develops empirically from existing applications in a relatively unstructured way and benefiting from the dynamic development of mobile technology. The possibilities range from viewing images at the bedside via mobile accessibility of radiologists up to teleradiology. In research there is a huge potential in solutions that actively involve patients with their own mobile devices but the field of data protection is still perceived in Germany as problematic so that only a few research institutions are actively addressing these options. The concept of mHealth allows physicians, hospitals and other service providers to invent entirely new services and a start-up scene is beginning to be established with business models becoming successful particularly with exchanges at the interface with established suppliers.

  9. Barriers to the use of mobile sales force automation systems: a salesperson’s perspective

    Sinisalo, Jaakko; Karjaluoto, Heikki; Saraniemi, Saila

    2015-01-01

    Purpose – The purpose of this paper is to examine the barriers associated with the adoption and use of mobile sales force automation (SFA) systems from a salesperson’s perspective. Design/methodology/approach – A qualitative investigation of two business-to-business companies was conducted. Data collected from ten semi-structured interviews with directors or sales managers were analyzed to understand the main barriers to SFA system adoption. Findings – The study confirms the ex...

  10. Barriers and benefits to using mobile health technology after operation: A qualitative study.

    Abelson, Jonathan S; Kaufman, Elinore; Symer, Matthew; Peters, Alexander; Charlson, Mary; Yeo, Heather

    2017-09-01

    Recently, mobile health technology has emerged as a promising avenue for improving physician-patient communication and patient outcomes. The objective of our study was to determine the public's perception of barriers and benefits to using mobile health technology technologies to enhance recovery after operation. We used the Empire State Poll to ask 2 open-ended questions to 800 participants assessing their perceptions of benefits and barriers to use mobile health technology after operation. All responses were coded independently, and any discrepancies were resolved by consensus. We used grounded theory to allow themes to arise from the codes. Interrater reliability was calculated using Cohen's Kappa. Participants identified a range of possible barriers to using mobile health technology apps after operation including: protecting personal health information, technology effectiveness and failure, preference for face-to-face interaction with their surgeon, level of effort required, and ability of the older adults to navigate mobile health technology. Participants identified multiple possible benefits including: better monitoring, improved communication with their surgeon, minimizing follow-up visits, improved convenience, and increased patient knowledge. In the study, 15% of all respondents stated there were no barriers whereas 6% stated there were no benefits. Participants were receptive to the many potential benefits of this technology to enhance not only their relationships with providers and the convenience of access, but also their health outcomes. We must address participants concerns about data security and their fears of losing a personal relationship with their doctor. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Patterns of geographic mobility predict barriers to engagement in HIV care and antiretroviral treatment adherence.

    Taylor, Barbara S; Reyes, Emily; Levine, Elizabeth A; Khan, Shah Z; Garduño, L Sergio; Donastorg, Yeycy; Hammer, Scott M; Brudney, Karen; Hirsch, Jennifer S

    2014-06-01

    Migration and geographic mobility increase risk for HIV infection and may influence engagement in HIV care and adherence to antiretroviral therapy. Our goal is to use the migration-linked communities of Santo Domingo, Dominican Republic, and New York City, New York, to determine the impact of geographic mobility on HIV care engagement and adherence to treatment. In-depth interviews were conducted with HIV+Dominicans receiving antiretroviral therapy, reporting travel or migration in the past 6 months and key informants (n=45). Mobility maps, visual representations of individual migration histories, including lifetime residence(s) and all trips over the past 2 years, were generated for all HIV+ Dominicans. Data from interviews and field observation were iteratively reviewed for themes. Mobility mapping revealed five distinct mobility patterns: travel for care, work-related travel, transnational travel (nuclear family at both sites), frequent long-stay travel, and vacation. Mobility patterns, including distance, duration, and complexity, varied by motivation for travel. There were two dominant barriers to care. First, a fear of HIV-related stigma at the destination led to delays seeking care and poor adherence. Second, longer trips led to treatment interruptions due to limited medication supply (30-day maximum dictated by programs or insurers). There was a notable discordance between what patients and providers perceived as mobility-induced barriers to care and the most common barriers found in the analysis. Interventions to improve HIV care for mobile populations should consider motivation for travel and address structural barriers to engagement in care and adherence.

  12. Mobile Application Removes Societal Barriers to P4 Medicine.

    Michel, J-P

    2017-01-01

    The overlap between one innovative paradigm (P4 medicine: predictive, personalized, participatory and preventive) and another (a new definition of "Healthy ageing") is fertile ground for new technologies; a new mobile application (app) that could broaden our scientific knowledge of the ageing process and help us to better analyse the impact of possible interventions in slowing the ageing decline. A novel mobile application is here presented as a game including questions and tests will allow in 10 minutes the assessment of the following domains: robustness, flexibility (lower muscle strength), balance, mental and memory complaints, semantic memory and visual retention. This game is completed by specific measurements, which could allow establishing precise information on functional and cognitive abilities. A global evaluation precedes advice and different types of exercises. The repetition of the tests and measures will allow a long follow up of the individual performances which could be shared (on specific request) with family members and general practitioners.

  13. Students' Perceptions of Edmodo and Mobile Learning and Their Real Barriers towards Them

    Al-Said, Khaleel M.

    2015-01-01

    The present research aims to investigate the students' perceptions levels of Edmodo and Mobile learning and to identify the real barriers of them at Taibah University in KSA. After implemented Edmodo application as an Mlearning platform, two scales were applied on the research sample, the first scale consisted of 36 statements was constructed to…

  14. Software-Based Adjustment of Mobile Autostereoscopic Graphics Using Static Parallax Barriers

    Paprocki, Martin Marko; Krog, Kim Srirat; Kristoffersen, Morten Bak

    2012-01-01

    We show that the autostereoscopic display of stereoscopic images using a static parallax barrier can be improved by adapting the rendering to the angle under which the user is looking at a mobile display; thus, ghosting artifacts and depth reversals can often be avoided even if the user tilts the...

  15. Investigating the extent to which mobile phones reduce Knowledge Transfer barriers in Student Project Teams

    Michael E. Kyobe

    2011-03-01

    Full Text Available Group learning plays a key role in the transfer of knowledge. In institutions of learning, it enhances students’ understanding, critical thinking, integration of knowledge and knowledge sharing. However, the transfer of knowledge in group projects is often impeded by factors such as time and budget constraints, individual and social barriers, and a lack of motivation.Institutions of learning are increasingly adopting information and communication technologies (e.g. mobile technologies to provide solutions to the challenges facing them. Whilst the integration of the mobile context and technologies in learning environment has been encouraged over the years, and indeed many students today can use mobile phones, the effectiveness of these technologies in reducing impediments to knowledge transfer in group learning has not been investigated.This study investigated the extent to which mobile phones reduce the barriers to knowledge transfer in project groups. The impediments examined include the nature of knowledge, social barriers, lack of time and lack of motivation. Quantitative and qualitative approaches were used to collect and analyse the data. The sample consisted of 85 students engaged in group projects in the departments of Information Systems, Civil Engineering, Computer Science and Construction Engineering.The results show that mobile phones reduce all four knowledge transfer barriers investigated in the project groups. We found no significant difference in the nature of knowledge shared by teams with weak and strong ties. This suggests that teams with weak social ties who normally experience difficulty sharing complex (tacit knowledge can easily do so with the aid of mobile facilities. In addition, frequent users of mobile phones were motivated to share explicit knowledge with their peers whilst those who often work with tacit knowledge could convert it to explicit form and share it with others. Mobile features like short messaging

  16. High tension generator for corona barrier discharge

    Baltag, O.; Costandache, D.; Gheorghiu, M.; Paraschivescu, A.; Popa, G.

    2001-01-01

    Different types of high-voltage generators are in use for the study of low pressure (or atmospheric) discharges. Mostly used are the Tesla coils generators or the power generators working in linear or switching regime. The Tesla coils generators have the advantage of a simple bloc diagram. In exchange, they have a number of short-comings, such as: the difficulty in modifying the frequency of the high voltage pulses, generation of a high voltage and frequency pulse train, the amplitude is not constant.This paper presents a high-voltage generator meant to be used in the study of the dielectric barrier discharges (DBD). The bloc diagram is presented. Performances obtained are as follows: - Generated frequency: 10 Hz - 100 Hz, 100 Hz - 1 KHz, 1 KHz - 10 KHz; - High voltage pulses control: a single pulse from an internal or external generator; - Synchronization with the oscilloscope, variable delay: 5 μs - 0.1 s; - Output voltage: variable both smoothly and in steps: 1 kV -15 kV; - High voltage polarity: mono and bipolar; - Output power during the continuous duty: 300 VA (maximum 600 VA for a short time); - Pulse energy: 0.23 J; - Pulse duration: 4 μs - 50 μs

  17. High Performance Multi Barrier Thermionic Devices

    Vashaee, Daryoosh; Shakouri, Ali

    2003-01-01

    Thermoelectric transport perpendicular to layers in multiple barrier superlattice structures is investigated theoretically in two limiting cases of no lateral momentum scattering and strong scattering...

  18. Investigating the extent to which mobile phones reduce Knowledge Transfer barriers in Student Project Teams

    Michael E. Kyobe

    2011-10-01

    Institutions of learning are increasingly adopting information and communication technologies (e.g. mobile technologies to provide solutions to the challenges facing them. Whilst the integration of the mobile context and technologies in learning environment has been encouraged over the years, and indeed many students today can use mobile phones, the effectiveness of these technologies in reducing impediments to knowledge transfer in group learning has not been investigated. This study investigated the extent to which mobile phones reduce the barriers to knowledge transfer in project groups. The impediments examined include the nature of knowledge, social barriers, lack of time and lack of motivation. Quantitative and qualitative approaches were used to collect and analyse the data. The sample consisted of 85 students engaged in group projects in the departments of Information Systems, Civil Engineering, Computer Science and Construction Engineering. The results show that mobile phones reduce all four knowledge transfer barriers investigated in the project groups. We found no significant difference in the nature of knowledge shared by teams with weak and strong ties. This suggests that teams with weak social ties who normally experience difficulty sharing complex (tacit knowledge can easily do so with the aid of mobile facilities. In addition, frequent users of mobile phones were motivated to share explicit knowledge with their peers whilst those who often work with tacit knowledge could convert it to explicit form and share it with others. Mobile features like short messaging service and multimedia messaging service (SMS & MMS or what some people refer to as ‘texting’, and email were mainly used to share knowledge and were perceived to reduce knowledge transfer time more than voice facilities. Our findings indicate that most students do not utilise the affordances of mobile phones for tacit knowledge transfer. Sharing of tacit knowledge needs to be encouraged

  19. Development of the Barriers to Physical Activity Questionnaire for People with Mobility Impairments.

    Vasudevan, Vijay; Rimmer, James H; Kviz, Frederick

    2015-10-01

    Despite the widely known benefits of physical activity, people with disabilities are more likely to be inactive when compared to people without disabilities. Previous questionnaires that measure barriers physical activity for people with disabilities do not measure barriers from an ecological perspective. The purpose of this study was to develop the Barriers to Physical Activity Questionnaire for People with Mobility Impairments (BPAQ-MI) that measures barriers using an ecological framework. This study consisted of two phases. In Phase one, developed the content validity by (a) developing an item bank, (b) identifying missing items and combining items using a Delphi panel, and (c) refine item wording via cognitive interviews. In Phase two, people with mobility impairments took part in in-person interviews to establish test-retest reliability, internal consistency, and construct validity of the BPAQ-MI. Exploratory factor analysis revealed the BPAQ-MI was comprised of eight subscales or factors: health; beliefs and attitudes; family; friends; fitness center built environment; staff and policy; community built environment; and safety. The BPAQ-MI demonstrated very good test-retest reliability. Cronbach's alpha ranged from 0.792 to 0.935. The BPAQ-MI showed significant negative correlations with exercise (minutes/week) and significant positive correlations between BPAQ-MI subscales and inactivity (hours/day). The BPAQ-MI is the first questionnaire that places greater equity at measuring barriers to physical activity across the intrapersonal, interpersonal, organizational, and community domains. The BPAQ-MI has the potential to assist researchers in understanding the complex relationship between barriers and ultimately develop physical activity interventions that address these barriers. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Low-impact, high toughness transportation barriers.

    2012-10-01

    Alternatives to existing transportation truck escape ramps and crash barriers are examined using arrays of : wood, bamboo, and fiberglass structural elements that act as energy absorbers as they deform. The : behaviors of each material type are analy...

  1. Food Access Patterns and Barriers among Midlife and Older Adults with Mobility Disabilities

    Deborah L. Huang

    2012-01-01

    Full Text Available We examined where midlife and older adults with a mobility disability accessed food outside the home in King County, Washington, USA, how they travelled to these food destinations, and facilitators and barriers to food access using qualitative interviews. Thirty-five adults aged ≥50 years with a mobility disability (defined as use of an assistive device for mobility were interviewed. Supplemental objective information was obtained from a Global Positioning System device worn by participants for 3 days. Participants primarily accessed food at grocery stores, restaurants, and coffee shops/cafés. The most common transportation modes were walking, obtaining a ride from friends, motorized chair/scooter, and public transit. Location and proximity of food destinations were factors affecting participants’ ability to access these destinations. Adequate space, ease of entry, available amenities such as restrooms, and helpful people were facilitators for participants to access food outside the home.

  2. Mobile Learning as a Method of Ubiquitous Learning: Students' Attitudes, Readiness, and Possible Barriers to Implementation in Higher Education

    Alhassan, Riyadh

    2016-01-01

    The purpose of this study was to explore the attitudes and level of readiness, and possible barriers to implementing Mobile Learning as a part of ubiquitous learning. In addition, the study attempted to find out to what extent students are interested in mobile learning. It also aimed to answer the question regarding the readiness of college…

  3. Analytical admittance characterization of high mobility channel

    Mammeri, A. M.; Mahi, F. Z., E-mail: fati-zo-mahi2002@yahoo.fr [Institute of Science and Technology, University of Bechar (Algeria); Varani, L. [Institute of Electronics of the South (IES - CNRS UMR 5214), University of Montpellier (France)

    2015-03-30

    In this contribution, we investigate the small-signal admittance of the high electron mobility transistors field-effect channels under a continuation branching of the current between channel and gate by using an analytical model. The analytical approach takes into account the linearization of the 2D Poisson equation and the drift current along the channel. The analytical equations discuss the frequency dependence of the admittance at source and drain terminals on the geometrical transistor parameters.

  4. CITY TRANSPORT IN BARRIER-FREE ARCHITECTURAL PLANNING SPACE FOR PEOPLE WITH LIMITED MOBILITY

    Pryadko Igor’ Petrovich

    2014-09-01

    Full Text Available This paper reviews the current state of transport organization for people with limited mobility. The article evaluates the results of the actions the executive authorities of Moscow and Moscow Region take. Barrier-free space organization for disabled people and parents with prams is given a special attention. The lack of strategy in the sphere leads to considerable difficulties for people with limited ability. This problem should be solved in cooperation with the survey of other peoples' needs. The article gives examples of comfortable urban space in Sochi, Moscow, Chita, Mytishchi and analyses the ways urbanism influences people with limited abilities.

  5. Use of mobile devices in community health care: barriers and solutions to implementation.

    Turner, Christopher

    2016-02-01

    Mobile devices allow clinicians to access electronic clinical systems away from traditional base locations. They have contributed to increased productivity and efficiency, and clinical staff also cite benefits to patient care. A selection of NHS trusts have participated in a national pilot to explore the benefits and drawbacks of this technology. Clinical engagement with frontline staff is essential to ensure the staff feel valued, listened to, and fully involved to ensure any change to existing practice is successful. Moreover, the training needs of the workforce require careful consideration. The provision of information technology (IT) support services is fundamental to ensure that staff receive the necessary assistance with any functionality issues they may experience with mobile devices to minimise the effect on clinical practice. Variability in internet connectivity may present as a challenge to clinical staff, and the benefits of complimentary offline working solutions should be considered. Barriers to the successful use of mobile devices should be reported as this may have a negative clinical effect on the safe delivery of patient care. Clinical staff need to be mindful of their obligations in relation to information governance, and should appreciate that the same consideration needs to be given to both paper and electronic records.

  6. Mobile Phone Ownership Is Not a Serious Barrier to Participation in Studies: Descriptive Study.

    Harvey, Emily J; Rubin, Leslie F; Smiley, Sabrina L; Zhou, Yitong; Elmasry, Hoda; Pearson, Jennifer L

    2018-02-19

    requiring participants to use their personal mobile phones for data collection was not a major barrier to study participation for most respondents who completed the online screener, including those who were unemployed. ClinicalTrials.gov NCT02261363; https://clinicaltrials.gov/ct2/show/NCT02261363 (Archived by WebCite at http://www.webcitation.org/6wOmDluSt). ©Emily J Harvey, Leslie F Rubin, Sabrina L Smiley, Yitong Zhou, Hoda Elmasry, Jennifer L Pearson. Originally published in JMIR Mhealth and Uhealth (http://mhealth.jmir.org), 19.02.2018.

  7. Mobilities

    to social networks, personal identities, and our relationship to the built environment. The omnipresence of mobilities within everyday life, high politics, technology, and tourism (to mention but a few) all point to a key insight harnessed by the ‘mobilities turn’. Namely that mobilities is much more than......The world is on the move. This is a widespread understanding by many inhabitants of contemporary society across the Globe. But what does it actually mean? During over one decade the ‘mobilities turn’ within the social sciences have provided a new set of insights into the repercussions of mobilities...... and environmental degradation. The spaces and territories marked by mobilities as well as the sites marked by the bypassing of such are explored. Moreover, the architectural and technological dimensions to infrastructures and sites of mobilities will be included as well as the issues of power, social exclusion...

  8. Chemical resilience of clay rich barrier materials to redox-oscillating conditions and implications for contaminant mobility

    Parsons, Chris; Rossetto, Lionel; Charlet, Laurent; Made, Benoit

    2012-01-01

    nitrate and sulphate in addition to the reductive dissolution of manganese and iron oxide minerals and an increase in CO 2 partial pressure. Whilst some authors demonstrate that such cyclic redox conditions may alter the properties of clay barrier materials due to illitisation of smectite clays (6, 7), the dynamic chemical conditions occurring during redox cycling may also result in the dissolution and re-precipitation of metal oxides, sulphides and carbonates. The balance of these minerals, even if present at sub-per cent levels as impurities has the potential to dramatically alter contaminant mobility. Many inorganic contaminants often associated with LL-LLW including Sb, Cr, As, Hg and U are also highly sensitive to changes in redox conditions which may result in changes to their speciation, toxicity and mobility (8, 9). We demonstrate through the combination of redox-stat batch-reactor experiments and thermodynamic modelling that periodic and cumulative changes to matrix mineralogy, contaminant speciation and mineral surface properties occur following periodic cycles of reduction and oxidation. These changes result in both short term (intra-cycle) and long-term (inter-cycle) changes to K d values for a range of redox sensitive contaminants associated with LL-LLW including arsenic, chromium, selenium, mercury and uranium (Table 1 and Figures 1 and 2). During a series of laboratory experiments argillaceous substrates were subjected to successive cycles of oxidising and reducing conditions with Eh oscillating between -215 and +340 mV induced via both abiotic and microbial methods. Chemically induced cycles of oxidation and reduction were achieved via a combination of gas sparging (nitrogen vs compressed air) and the addition of a synthetic reduced humic substance analogue (AH 2 DS 2- ). Microbially induced cycles of oxidation and reduction were achieved using gas sparging (nitrogen vs compressed air) to stimulate different metabolic pathways of a natively present

  9. Mobile Data Technologies and SME Adoption and Diffusion: an empirical study of barriers and facillitators

    Jeanette Van Akkeren

    2002-05-01

    Full Text Available The technological environment in which Australian SMEs operate can be best described as dynamic and vital. The rate of technological change provides the SME owner/manger a complex and challenging operational context. Wireless applications are being developed that provide mobile devices with Internet content and E-business services. In Australia, the adoption of ecommerce by large organisations has been relatively high, however, the same cannot be said for SMEs, where adoption has been slower than other developed countries. In contrast, however, mobile telephone adoption and diffusion is relatively high by SMEs. Will SMEs who have been reluctant to adopt commerce technologies in the past be more ready to go on-line with the merging of the Internet and mobile data technologies? This exploratory study identifies attitudes, perceptions and issues for mobile data technologies by regional SME owner/managers across a range of industry sectors. The major issues include the sector the firm belongs to, the current adoption status of the firm, the level of mistrust of the IT industry, the cost of the technologies, and the applications and attributes of the technologies.

  10. Carbon doped GaAs/AlGaAs heterostructures with high mobility two dimensional hole gas

    Hirmer, Marika; Bougeard, Dominique; Schuh, Dieter [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D 93040 Regensburg (Germany); Wegscheider, Werner [Laboratorium fuer Festkoerperphysik, ETH Zuerich, 8093 Zuerich (Switzerland)

    2011-07-01

    Two dimensional hole gases (2DHG) with high carrier mobilities are required for both fundamental research and possible future ultrafast spintronic devices. Here, two different types of GaAs/AlGaAs heterostructures hosting a 2DHG were investigated. The first structure is a GaAs QW embedded in AlGaAs barrier grown by molecular beam epitaxy with carbon-doping only at one side of the quantum well (QW) (single side doped, ssd), while the second structure is similar but with symmetrically arranged doping layers on both sides of the QW (double side doped, dsd). The ssd-structure shows hole mobilities up to 1.2*10{sup 6} cm{sup 2}/Vs which are achieved after illumination. In contrast, the dsd-structure hosts a 2DHG with mobility up to 2.05*10{sup 6} cm{sup 2}/Vs. Here, carrier mobility and carrier density is not affected by illuminating the sample. Both samples showed distinct Shubnikov-de-Haas oscillations and fractional quantum-Hall-plateaus in magnetotransport experiments done at 20mK, indicating the high quality of the material. In addition, the influence of different temperature profiles during growth and the influence of the Al content of the barrier Al{sub x}Ga{sub 1-x}As on carrier concentration and mobility were investigated and are presented here.

  11. Cassette pontoon bridge of high mobility

    Krzysztof KOSIUCZENKO

    2011-01-01

    Full Text Available Looking through the known and used buoyant systems, it can be remarked that the single buoyant segments are the stiff objects made of steel or plastic with variable dimensions and a complex construction. The ready to use buoyant segments, that assure the proper displacement, must have the factory leak-tightness. They take up a big transportation volume and need the assurance of the suitably abundant means of transport. Usually the heavy wheeled vehicles are needed because of high own mass of buoyant segment and large gauges. The exploitation of such constructions is very expensive. A cassette pontoon bridge, presented in this paper, is the proposition of the increase of the mobility of construction. The decrease of the single buoyant segment dimensions with the assurance of the capacity leads that more segments fit into in the same dimensions of the loading compartment of the vehicle and storage accommodation. The application of standardized joints assures the assembly efficiency with not numerous crew.

  12. Application of diffusion barriers to high modulus fibers

    Veltri, R. D.; Douglas, F. C.; Paradis, E. L.; Galasso, F. S.

    1977-01-01

    Barrier layers were coated onto high-modulus fibers, and nickel and titanium layers were overcoated as simulated matrix materials. The objective was to coat the high-strength fibers with unreactive selected materials without degrading the fibers. The fibers were tungsten, niobium, and single-crystal sapphire, while the materials used as barrier coating layers were Al2O3, Y2O3, TiC, ZrC, WC with 14% Co, and HfO2. An ion-plating technique was used to coat the fibers. The fibers were subjected to high-temperature heat treatments to evaluate the effectiveness of the barrier layer in preventing fiber-metal interactions. Results indicate that Al2O3, Y2O3, and HfO2 can be used as barrier layers to minimize the nickel-tungsten interaction. Further investigation, including thermal cycling tests at 1090 C, revealed that HfO2 is probably the best of the three.

  13. C-RAM: breaking mobile device memory barriers using the cloud

    Pamboris, A; Pietzuch, P

    2015-01-01

    ?Mobile applications are constrained by the available memory of mobile devices. We present C-RAM, a system that uses cloud-based memory to extend the memory of mobile devices. It splits application state and its associated computation between a mobile device and a cloud node to allow applications to consume more memory, while minimising the performance impact. C-RAM thus enables developers to realise new applications or port legacy desktop applications with a large memory footprint to mobile ...

  14. High mobility and high concentration Type-III heterojunction FET

    Tsu, R.; Fiddy, M. A.; Her, T.

    2018-02-01

    The PN junction was introduced in transistors by doping, resulting in high losses due to Coulomb scattering from the dopants. The MOSFET introduced carriers in the form of electrons and holes with an applied bias to the oxide barrier, resulting in carrier transfer without doping. This avoids high scattering losses and dominates the IC industries. With heterojunctions having valence-band maxima near and even above the conduction-band minimum in the formation of Type-III superlattices, very useful devices, introduced by Tsu, Sai-Halacz, and Esaki, soon followed. If the layer thicknesses are more than the carrier mean-free-path, incoherent scattering results in the formation of carrier transfer via diffusion instead of opening up new energy gaps. The exploitation of carriers without scattering represents a new and significant opportunity in what we call a Broken Gap Heterojunction FET.

  15. High school students’ usage behavior and views about mobile phones

    Ahmet Ergin

    2014-09-01

    Full Text Available Objective: The aim of this study was to determine high school students’ usage behavior and views about mobile phones. Methods:Totally 253 (85.5% students educated at Honaz High School within the academic year 2010-2011, participated to this cross-sectional study and a questionnaire consisting of 42 questions which aimed to determine usage behavior and views about mobile phones was administered to the students. Results:The mean age of the students was 16.1 ± 1.1 years, and 56.9% of them were girl. 79.8% of students have mobile phone and 53.9% of them make daily average of over 30 minutes mobile phone calls. 76.1% of participants stated that they did not use headphones, 78.1% did not turn off their mobile phones when they are sleeping and 67.3% put it right next to them or under the pillow. 83.1% of students think mobile phones are harmful for human health, 56.7% think the base stations are harmful to human health and the environment, 91.3% think mobile phones are harmful for children, pregnant women and elderly people. Conclusion: It is found that students’ mobile phone ownership is widespread, the age of starting to use mobile phone and headphones usage is low, knowledge about the base stations is not adequate.

  16. Provider perceptions of barriers and facilitators of HPV vaccination in a high-risk community.

    Javanbakht, Marjan; Stahlman, Shauna; Walker, Susan; Gottlieb, Sami; Markowitz, Lauri; Liddon, Nicole; Plant, Aaron; Guerry, Sarah

    2012-06-22

    Maximizing HPV vaccine uptake among those at highest risk for cervical cancer is critical. We explored healthcare provider perspectives on factors influencing HPV vaccination among adolescent girls in a community with high cervical cancer rates. From March to May 2009, we conducted in-depth interviews with 21 medical staff providing care to adolescent girls at two clinics in Los Angeles, CA, serving a predominantly Hispanic population with high cervical cancer rates. Interviews were recorded and transcribed data were reviewed for coding and thematic content related to potential barriers and facilitators of HPV vaccination. Providers and medical staff overwhelmingly focused on parental beliefs as barriers to HPV vaccination. Perceived parental misconceptions acting as barriers included the belief that adolescents do not need vaccinations and that no-cost vaccine programs like Vaccines for Children are only available for younger children. Perceived parental concerns that the vaccine will promote sexual activity were prevalent, which prompted providers to frame HPV vaccine as a "routine" vaccine. However, the medical staff felt mothers with a friend or relative supportive of HPV vaccination were more likely to request the vaccine. The staff also noted that for Hispanic parents the "preferred" source of information is peers; if the "right people" in the community were supportive of HPV vaccine, parents were more willing to vaccinate. Other barriers included lack of immunization records among immigrant parents and a difficult-to-reach, mobile clientele. Providers noted a number of barriers to HPV vaccination, including some perceived parental misconceptions that could be addressed with education about the need for adolescent vaccines and available free vaccine programs. Because community support appears particularly important to Hispanic parents, the use of promotoras - peer liaisons between health organizations and the community - may increase HPV vaccine uptake in

  17. Micromagnetics on high-performance workstation and mobile computational platforms

    Fu, S.; Chang, R.; Couture, S.; Menarini, M.; Escobar, M. A.; Kuteifan, M.; Lubarda, M.; Gabay, D.; Lomakin, V.

    2015-05-01

    The feasibility of using high-performance desktop and embedded mobile computational platforms is presented, including multi-core Intel central processing unit, Nvidia desktop graphics processing units, and Nvidia Jetson TK1 Platform. FastMag finite element method-based micromagnetic simulator is used as a testbed, showing high efficiency on all the platforms. Optimization aspects of improving the performance of the mobile systems are discussed. The high performance, low cost, low power consumption, and rapid performance increase of the embedded mobile systems make them a promising candidate for micromagnetic simulations. Such architectures can be used as standalone systems or can be built as low-power computing clusters.

  18. Information Use and Barriers on a Mobile App in Distance Learning

    Du, Yunfei

    2015-01-01

    Mobile technologies such as iPhone apps make it possible for learners to freely access course content management systems, library Web sites, as well as reference services from anywhere, anytime. This paper reviewed the current status of mobile learning and suggested possible factors influencing the use of mobile apps in online learning. The author…

  19. Physical activity barriers and motivators among high-risk employees.

    Paguntalan, John C; Gregoski, Mathew

    2016-11-22

    Worksite wellness programs offer an ideal setting to target high-risk sedentary workers to improve health status. Lack of physical activity is associated with increased risk for coronary heart disease and mortality. Despite the risks, the number of sedentary workers is increasing. This study examined the perceived barriers and motivators for physical activity among employees at high-risk for coronary heart disease. A purposive sample of 24 high-risk workers participating in a wellness program in rural South Carolina were enrolled in the study. Qualitative data was obtained through semi-structured face-to-face interviews. Grounded theory was used to analyze qualitative data, and identify overarching themes. Physical limitations due to pain and weakness, lack of motivation, and lack of time emerged as the main barriers to physical activity. Family relationships were reported as the strongest motivator along with social support and potential health benefits. Findings highlight the unique experience of high-risk workers with physical activity. The findingsunderscore the need to design and implement effective interventions specifically designed to meet the needs of high-risk employees.

  20. Understanding the barriers to successful adoption and use of a mobile health information system in a community health center in São Paulo, Brazil: a cohort study.

    Rajan, Jayant V; Moura, Juliana; Gourley, Gato; Kiso, Karina; Sizilio, Alexandre; Cortez, Ana Maria; Riley, Lee W; Veras, Maria Amelia; Sarkar, Urmimala

    2016-11-17

    Mobile technology to support community health has surged in popularity, yet few studies have systematically examined usability of mobile platforms for this setting. We conducted a mixed-methods study of 14 community healthcare workers at a public healthcare clinic in São Paulo, Brazil. We held focus groups with community healthcare workers to elicit their ideas about a mobile health application and used this input to build a prototype app. A pre-use test survey was administered to all participants, who subsequently use-tested the app on three different devices (iPhone, iPad mini, iPad Air). Usability was assessed by objectively scored data entry errors and through a post-use focus group held to gather open-ended feedback on end-user satisfaction. All of the participants were women, ranging from 18-64 years old. A large percentage (85.7%) of participants had at least a high school education. Internet (92.8%), computer (85.7%) and cell phone (71.4%) use rates were high. Data entry error rates were also high, particularly in free text fields, ranging from 92.3 to 100%. Error rates were comparable across device type. In a post-use focus group, participants reported that they found the app easy to use and felt that its design was consistent with their vision. The participants raised several concerns, including that they did not find filling out the forms in the app to be a useful task. They also were concerned about an app potentially creating more work for them and personal security issues related to carrying a mobile device in low-income areas. In a cohort of formally educated community healthcare workers with high levels of personal computer and cell phone use, we identified no technological barriers to adapting their existing work to a mobile device based system. Transferring current data entry work into a mobile platform, however, uncovered underlying dissatisfaction with some data entry tasks. This dissatisfaction may be a more significant barrier than the data

  1. The key drivers and barriers to the use of Mobile Payments from consumer's perspective

    Sunna, Shadi

    2013-01-01

    The nearly ubiquitous presence and the continually expanding capabilities of the mobile devices as well as the evolution of the smartphones provide an additional channel for payments, improve the shopping experience and present cutting-edge opportunities for merchants to involve consumers, and drive sales. Despite the positive prediction in past years in relation to the growth, mobile payment services have failed to seduce consumers. The problem of the mass adoption of mobile payments in gene...

  2. Many Mobile Health Apps Target High-Need, High-Cost Populations, But Gaps Remain.

    Singh, Karandeep; Drouin, Kaitlin; Newmark, Lisa P; Lee, JaeHo; Faxvaag, Arild; Rozenblum, Ronen; Pabo, Erika A; Landman, Adam; Klinger, Elissa; Bates, David W

    2016-12-01

    With rising smartphone ownership, mobile health applications (mHealth apps) have the potential to support high-need, high-cost populations in managing their health. While the number of available mHealth apps has grown substantially, no clear strategy has emerged on how providers should evaluate and recommend such apps to patients. Key stakeholders, including medical professional societies, insurers, and policy makers, have largely avoided formally recommending apps, which forces patients to obtain recommendations from other sources. To help stakeholders overcome barriers to reviewing and recommending apps, we evaluated 137 patient-facing mHealth apps-those intended for use by patients to manage their health-that were highly rated by consumers and recommended by experts and that targeted high-need, high-cost populations. We found that there is a wide variety of apps in the marketplace but that few apps address the needs of the patients who could benefit the most. We also found that consumers' ratings were poor indications of apps' clinical utility or usability and that most apps did not respond appropriately when a user entered potentially dangerous health information. Going forward, data privacy and security will continue to be major concerns in the dissemination of mHealth apps. Project HOPE—The People-to-People Health Foundation, Inc.

  3. Barriers to Effective Learning of High School Students in Turkey

    Eda Gürlen

    2016-06-01

    Full Text Available This study aims to present the development and validation process of a scale to explore the learning barriers of high school students in Turkey. For this purpose, a scale was developed and administered to 316 high school students studying in the different counties of Ankara in the spring term of 2014-2015 academic year. Gathering the data, an exploratory factor analysis was run through SPSS Package program to see the structure of the interrelationships among the variables under six tests. Furthermore, a reliability analysis was conducted to the items under each test in the scale. As a result, one factor appeared under each test when the eigenvalues and variance percentages were examined, making six factors in total. The Cronbach’s Alpha Reliability Coefficient was calculated as to be significant for each test, which showed that the tests were reliable. Finally, some items were excluded from the scale.

  4. High mobility transparent conducting oxides for thin film solar cells

    Calnan, S.; Tiwari, A.N.

    2010-01-01

    A special class of transparent conducting oxides (TCO) with high mobility of > 65 cm 2 V -1 s -1 allows film resistivity in the low 10 -4 Ω cm range and a high transparency of > 80% over a wide spectrum, from 300 nm to beyond 1500 nm. This exceptional coincidence of desirable optical and electrical properties provides opportunities to improve the performance of opto-electronic devices and opens possibilities for new applications. Strategies to attain high mobility (HM) TCO materials as well as the current status of such materials based on indium and cadmium containing oxides are presented. Various concepts used to understand the underlying mechanisms for high mobility in HMTCO films are discussed. Examples of HMTCO layers used as transparent electrodes in thin film solar cells are used to illustrate possible improvements in solar cell performance. Finally, challenges and prospects for further development of HMTCO materials are discussed.

  5. High level bacterial contamination of secondary school students' mobile phones.

    Kõljalg, Siiri; Mändar, Rando; Sõber, Tiina; Rööp, Tiiu; Mändar, Reet

    2017-06-01

    While contamination of mobile phones in the hospital has been found to be common in several studies, little information about bacterial abundance on phones used in the community is available. Our aim was to quantitatively determine the bacterial contamination of secondary school students' mobile phones. Altogether 27 mobile phones were studied. The contact plate method and microbial identification using MALDI-TOF mass spectrometer were used for culture studies. Quantitative PCR reaction for detection of universal 16S rRNA, Enterococcus faecalis 16S rRNA and Escherichia coli allantoin permease were performed, and the presence of tetracycline ( tet A, tet B, tet M), erythromycin ( erm B) and sulphonamide ( sul 1) resistance genes was assessed. We found a high median bacterial count on secondary school students' mobile phones (10.5 CFU/cm 2 ) and a median of 17,032 bacterial 16S rRNA gene copies per phone. Potentially pathogenic microbes ( Staphylococcus aureus , Acinetobacter spp. , Pseudomonas spp., Bacillus cereus and Neisseria flavescens ) were found among dominant microbes more often on phones with higher percentage of E. faecalis in total bacterial 16S rRNA. No differences in contamination level or dominating bacterial species between phone owner's gender and between phone types (touch screen/keypad) were found. No antibiotic resistance genes were detected on mobile phone surfaces. Quantitative study methods revealed high level bacterial contamination of secondary school students' mobile phones.

  6. Nanomechanical Behavior of High Gas Barrier Multilayer Thin Films.

    Humood, Mohammad; Chowdhury, Shahla; Song, Yixuan; Tzeng, Ping; Grunlan, Jaime C; Polycarpou, Andreas A

    2016-05-04

    Nanoindentation and nanoscratch experiments were performed on thin multilayer films manufactured using the layer-by-layer (LbL) assembly technique. These films are known to exhibit high gas barrier, but little is known about their durability, which is an important feature for various packaging applications (e.g., food and electronics). Films were prepared from bilayer and quadlayer sequences, with varying thickness and composition. In an effort to evaluate multilayer thin film surface and mechanical properties, and their resistance to failure and wear, a comprehensive range of experiments were conducted: low and high load indentation, low and high load scratch. Some of the thin films were found to have exceptional mechanical behavior and exhibit excellent scratch resistance. Specifically, nanobrick wall structures, comprising montmorillonite (MMT) clay and polyethylenimine (PEI) bilayers, are the most durable coatings. PEI/MMT films exhibit high hardness, large elastic modulus, high elastic recovery, low friction, low scratch depth, and a smooth surface. When combined with the low oxygen permeability and high optical transmission of these thin films, these excellent mechanical properties make them good candidates for hard coating surface-sensitive substrates, where polymers are required to sustain long-term surface aesthetics and quality.

  7. Mobile high-voltage switchboard. Variable and uncomplicated; Mobile Hochspannungsschaltanlage. Variabel und unkompliziert in der Anwendung

    Albert, Andreas [Siemens AG, Erlangen (Germany). Sector Energy

    2009-07-13

    The mobile high-voltage switchboard ''REE-Movil 2'' for voltages up to 245 kV provides a complete and nearly autonomous switchboard in a container, a solution that has been available in the medium-voltage sector for some time already. It can be used whenever a quick replacement of a switchboard section or a temporary supplement to a switching substation is needed. The container is mounted on a trailer for maximum flexibility and mobility. (orig.)

  8. High mobility and quantum well transistors design and TCAD simulation

    Hellings, Geert

    2013-01-01

    For many decades, the semiconductor industry has miniaturized transistors, delivering increased computing power to consumers at decreased cost. However, mere transistor downsizing does no longer provide the same improvements. One interesting option to further improve transistor characteristics is to use high mobility materials such as germanium and III-V materials. However, transistors have to be redesigned in order to fully benefit from these alternative materials. High Mobility and Quantum Well Transistors: Design and TCAD Simulation investigates planar bulk Germanium pFET technology in chapters 2-4, focusing on both the fabrication of such a technology and on the process and electrical TCAD simulation. Furthermore, this book shows that Quantum Well based transistors can leverage the benefits of these alternative materials, since they confine the charge carriers to the high-mobility material using a heterostructure. The design and fabrication of one particular transistor structure - the SiGe Implant-Free Qu...

  9. The Long Way From Government Open Data to Mobile Health Apps: Overcoming Institutional Barriers in the US Federal Government.

    Mergel, Ines

    2014-12-23

    Government agencies in the United States are creating mobile health (mHealth) apps as part of recent policy changes initiated by the White House's Digital Government Strategy. The objective of the study was to understand the institutional and managerial barriers for the implementation of mHealth, as well as the resulting adoption pathways of mHealth. This article is based on insights derived from qualitative interview data with 35 public managers in charge of promoting the reuse of open data through Challenge.gov, the platform created to run prizes, challenges, and the vetting and implementation of the winning and vendor-created apps. The process of designing apps follows three different pathways: (1) entrepreneurs start to see opportunities for mobile apps, and develop either in-house or contract out to already vetted Web design vendors; (2) a top-down policy mandates agencies to adopt at least two customer-facing mobile apps; and (3) the federal government uses a policy instrument called "Prizes and Challenges", encouraging civic hackers to design health-related mobile apps using open government data from HealthData.gov, in combination with citizen needs. All pathways of the development process incur a set of major obstacles that have to be actively managed before agencies can promote mobile apps on their websites and app stores. Beyond the cultural paradigm shift to design interactive apps and to open health-related data to the public, the managerial challenges include accessibility, interoperability, security, privacy, and legal concerns using interactive apps tracking citizen.

  10. High-resolution reconstruction of a coastal barrier system

    Fruergaard, Mikkel; Andersen, Thorbjørn Joest; Nielsen, Lars Henrik

    2015-01-01

    This study presents a detailed reconstruction of the sedimentary effects of Holocene sea-level rise on a modern coastal barrier system (CBS). Increasing concern over the evolution of CBSs due to future accelerated rates of sea-level rise calls for a better understanding of coastal barriers response...... from retreat of the barrier island and probably also due to formation of a tidal inlet close to the study area. Continued transgression and shoreface retreat created a distinct hiatus and wave ravinement surface in the seaward part of the CBS before the barrier shoreline stabilised between 5.0 and 4...

  11. An Architecture Offering Mobile Pollution Sensing with High Spatial Resolution

    Oscar Alvear

    2016-01-01

    Full Text Available Mobile sensing is becoming the best option to monitor our environment due to its ease of use, high flexibility, and low price. In this paper, we present a mobile sensing architecture able to monitor different pollutants using low-end sensors. Although the proposed solution can be deployed everywhere, it becomes especially meaningful in crowded cities where pollution values are often high, being of great concern to both population and authorities. Our architecture is composed of three different modules: a mobile sensor for monitoring environment pollutants, an Android-based device for transferring the gathered data to a central server, and a central processing server for analyzing the pollution distribution. Moreover, we analyze different issues related to the monitoring process: (i filtering captured data to reduce the variability of consecutive measurements; (ii converting the sensor output to actual pollution levels; (iii reducing the temporal variations produced by mobile sensing process; and (iv applying interpolation techniques for creating detailed pollution maps. In addition, we study the best strategy to use mobile sensors by first determining the influence of sensor orientation on the captured values and then analyzing the influence of time and space sampling in the interpolation process.

  12. Toll free mobile communication: overcoming barriers in maternal and neonatal emergencies in Rural Bangladesh.

    Huq, Nafisa Lira; Azmi, Asrafi Jahan; Quaiyum, M A; Hossain, Shahed

    2014-07-12

    Toll free mobile telephone intervention to support mothers in pregnancy and delivery period was tested in one sub district of Bangladesh. Qualitative research was conducted to measure the changes of mobile phone use in increasing communication for maternal and neonatal complications. In-depth interviews were conducted among twelve Community Skilled Birth Attendants and fourteen mothers along with their husbands prior to intervention. At intervention end, six Community Skilled Birth Attendants were purposively selected for in-depth interview. Semi structured interviews were conducted among all 27 Community Skilled Birth Attendants engaged in the intervention. One Focus Group Discussion was conducted with 10 recently delivered mothers. Thematic analysis and triangulation of different responses were conducted. Prior to intervention, Community Skilled Birth Attendants reported that mobile communication was not a norm. It was also revealed that poor mothers had poor accessibility to mobile services. Mothers, who communicated through mobile phone with providers noted irritability from Community Skilled Birth Attendants and sometimes found phones switched off. At the end of the project, 85% of mothers who had attended orientation sessions of the intervention communicated with Community Skilled Birth Attendants through mobile phones during maternal health complications. Once a complication is reported or anticipated over phone, Community Skilled Birth Attendants either made a prompt visit to mothers or advised for direct referral. More than 80% Community Skilled Birth Attendants communicated with Solution Linked Group for guidance on maternal health management. Prior to intervention, Solution Linked Group was not used to receive phone call from Community Skilled Birth Attendants. Community Skilled Birth Attendants were valued by the mothers. Mothers viewed that Community Skilled Birth Attendants are becoming confident in managing complication due to communication with

  13. Opportunities and barriers in service delivery through mobile phones (mHealth) for Severe Mental Illnesses in Rajasthan, India: A multi-site study.

    Jain, Nikhil; Singh, Harful; Koolwal, Ghanshyam Das; Kumar, Sunil; Gupta, Aditya

    2015-04-01

    Widespread use of mobile technology holds a lot of promise for mental health service delivery in regions where mental health resources are scarce and the treatment gap is large. The felt needs of the clients, and the patterns and barriers of mobile usage must be understood before some intervention can be planned. The study presented in this paper was designed to fill this gap in the region of Rajasthan, India. The study was conducted in three tertiary care hospitals. Clients utilizing services for Severe Mental Illnesses (SMIs) were the participants of the study. Information about ownership, usage patterns and barriers to accessing mobile technology and felt needs in terms of mental health services that could be delivered through mobile phones were sought from the participants. The typical respondents in all three centres were middle-aged, married, Hindu males belonging to lower socio-economic strata from rural background. Seventy two to 92% of participants had access to mobile phone. The most preferred mode of service delivery was through calls. Helpline for crisis resolution and telephonic follow-up of stable patients emerged as the most felt need of the participants. Barriers to mobile phones usage included affordability, lack of necessity, poor signal. In conclusion, the study shows that the access to mobile phones amongst clients receiving services for SMI is widespread and offers new opportunities in service delivery in the region. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Highly Mobile Students: Educational Problems and Possible Solutions. ERIC/CUE Digest, Number 73.

    ERIC Clearinghouse on Urban Education, New York, NY.

    The following two types of student mobility stand out as causing educational problems: (1) inner-city mobility, which is prompted largely by fluctuations in the job market; and (2) intra-city mobility, which is caused by upward mobility or by poverty and homelessness. Most research indicates that high mobility negatively affects student…

  15. Thermal barrier coatings (TBC's) for high heat flux thrust chambers

    Bradley, Christopher M.

    -section components has become critical, but at the same time the service conditions have put our best alloy systems to their limits. As a result, implementation of cooling holes and thermal barrier coatings are new advances in hot-section technologies now looked at for modifications to reach higher temperature applications. Current thermal barrier coatings used in today's turbine applications is known as 8%yttria-stabilized zirconia (YSZ) and there are no coatings for current thrust chambers. Current research is looking at the applicability of 8%yttria-stabilized hafnia (YSH) for turbine applications and the implementation of 8%YSZ onto thrust chambers. This study intends to determine if the use of thermal barrier coatings are applicable for high heat flux thrust chambers using industrial YSZ will be advantageous for improvements in efficiency, thrust and longer service life by allowing the thrust chambers to be used more than once.

  16. Barriers to Securing Data on Bluetooth®-Enabled Mobile Devices: A Phenomenological Study

    Hines, Natasha

    2015-01-01

    Company data on mobile devices is vulnerable and subject to unauthorized access. The general problem is that information security incidents compromise the integrity and authenticity of electronic data. The specific problem is that organizational security policies, procedures, and training do not adequately address the vulnerabilities associated…

  17. Interface-controlled, high-mobility organic transistors

    Jurchescu, Oana D.; Popinciuc, Mihaita; van Wees, Bart J.; Palstra, Thomas T. M.

    2007-01-01

    The achievement of high mobilities in field-effect transistors (FETs) is one of the main challenges for the widespread application of organic conductors in devices. Good device performance of a single-crystal pentacene FET requires both removal of impurity molecules from the bulk and the

  18. High mobility polymer gated organic field effect transistor using zinc ...

    Organic thin film transistors were fabricated using evaporated zinc phthalocyanine as the active layer. Parylene film ... At room temperature, these transistors exhibit p-type conductivity with field-effect ... Keywords. Organic semiconductor; field effect transistor; phthalocyanine; high mobility. ... The evaporation rate was kept at ...

  19. Enhanced mobility in vertically scaled N-polar high-electron-mobility transistors using GaN/InGaN composite channels

    Li, Haoran; Wienecke, Steven; Romanczyk, Brian; Ahmadi, Elaheh; Guidry, Matthew; Zheng, Xun; Keller, Stacia; Mishra, Umesh K.

    2018-02-01

    A GaN/InGaN composite channel design for vertically scaled N-polar high-electron-mobility transistor (HEMT) structures is proposed and demonstrated by metal-organic chemical vapor deposition. In a conventional N-polar HEMT structure, as the channel thickness (tch) decreases, the sheet charge density (ns) decreases, the electric field in the channel increases, and the centroid of the two-dimensional electron gas (2DEG) moves towards the back-barrier/channel interface, resulting in stronger scattering and lower electron mobility (μ). In this study, a thin InGaN layer was introduced in-between the channel and the AlGaN cap to increase the 2DEG density and reduce the electric field in the channel and therefore increase the electron mobility. The dependence of μ on the InGaN thickness (tInGaN) and the indium composition (xIn) was investigated for different channel thicknesses. With optimized tInGaN and xIn, significant improvements in electron mobility were observed. For a 6 nm channel HEMT structure, the electron mobility increased from 606 to 1141 cm2/(V.s) when the 6 nm thick pure GaN channel was replaced by the 4 nm GaN/2 nm In0.1Ga0.9N composite channel.

  20. High-frequency hearing loss among mobile phone users.

    Velayutham, P; Govindasamy, Gopala Krishnan; Raman, R; Prepageran, N; Ng, K H

    2014-01-01

    The objective of this study is to assess high frequency hearing (above 8 kHz) loss among prolonged mobile phone users is a tertiary Referral Center. Prospective single blinded study. This is the first study that used high-frequency audiometry. The wide usage of mobile phone is so profound that we were unable to find enough non-users as a control group. Therefore we compared the non-dominant ear to the dominant ear using audiometric measurements. The study was a blinded study wherein the audiologist did not know which was the dominant ear. A total of 100 subjects were studied. Of the subjects studied 53% were males and 47% females. Mean age was 27. The left ear was dominant in 63%, 22% were dominant in the right ear and 15% did not have a preference. This study showed that there is significant loss in the dominant ear compared to the non-dominant ear (P mobile phone revealed high frequency hearing loss in the dominant ear (mobile phone used) compared to the non dominant ear.

  1. Mobile and cordless telephones, serum transthyretin and the blood-cerebrospinal fluid barrier: a cross-sectional study

    Carlberg Michael

    2009-04-01

    Full Text Available Abstract Background Whether low-intensity radiofrequency radiation damages the blood-brain barrier has long been debated, but little or no consideration has been given to the blood-cerebrospinal fluid barrier. In this cross-sectional study we tested whether long-term and/or short-term use of wireless telephones was associated with changes in the serum transthyretin level, indicating altered transthyretin concentration in the cerebrospinal fluid, possibly reflecting an effect of radiation. Methods One thousand subjects, 500 of each sex aged 18–65 years, were randomly recruited using the population registry. Data on wireless telephone use were assessed by a postal questionnaire and blood samples were analyzed for serum transthyretin concentrations determined by standard immunonephelometric techniques on a BN Prospec® instrument. Results The response rate was 31.4%. Logistic regression of dichotomized TTR serum levels with a cut-point of 0.31 g/l on wireless telephone use yielded increased odds ratios that were statistically not significant. Linear regression of time since first use overall and on the day that blood was withdrawn gave different results for males and females: for men significantly higher serum concentrations of TTR were seen the longer an analogue telephone or a mobile and cordless desktop telephone combined had been used, and in contrast, significantly lower serum levels were seen the longer an UMTS telephone had been used. Adjustment for fractions of use of the different telephone types did not modify the effect for cumulative use or years since first use for mobile telephone and DECT, combined. For women, linear regression gave a significant association for short-term use of mobile and cordless telephones combined, indicating that the sooner blood was withdrawn after the most recent telephone call, the higher the expected transthyretin concentration. Conclusion In this hypothesis-generating descriptive study time since first

  2. High mobility solution-processed hybrid light emitting transistors

    Walker, Bright; Kim, Jin Young; Ullah, Mujeeb; Burn, Paul L.; Namdas, Ebinazar B.; Chae, Gil Jo; Cho, Shinuk; Seo, Jung Hwa

    2014-01-01

    We report the design, fabrication, and characterization of high-performance, solution-processed hybrid (inorganic-organic) light emitting transistors (HLETs). The devices employ a high-mobility, solution-processed cadmium sulfide layer as the switching and transport layer, with a conjugated polymer Super Yellow as an emissive material in non-planar source/drain transistor geometry. We demonstrate HLETs with electron mobilities of up to 19.5 cm 2 /V s, current on/off ratios of >10 7 , and external quantum efficiency of 10 −2 % at 2100 cd/m 2 . These combined optical and electrical performance exceed those reported to date for HLETs. Furthermore, we provide full analysis of charge injection, charge transport, and recombination mechanism of the HLETs. The high brightness coupled with a high on/off ratio and low-cost solution processing makes this type of hybrid device attractive from a manufacturing perspective

  3. Radiofrequency field emitted by mobile phones and alteration of the blood-brain barrier: how strong is the experimental evidence?

    Lagroye, I.; Haro, E.; Billaudel, B.; Ruffie, G.; Poulletier de Gannes, F.; Taxile, M.; Laclau, M.; Veyret, B.; Leveque, P.

    2006-01-01

    Full text of publication follows: It is known that high power, thermal radiofrequency radiation (RFR) can alter the blood-brain barrier (BBB) permeability with a brain averaged specific absorption rate (BASAR) threshold evaluated at around 100 W/kg (1). Mobile communication technologies are using RFR with exposure guidelines for public local exposure at 2 W/kg, far lower than the threshold previously mentioned. However, in a paper recently published (2) the occurrence of BBB leakage and brain damage (presence of dark neurons) has been reported 50 days after a single 2-hour exposure of rats to a GSM-900 signal. In that investigation however, bias could have occurred as, for instance, exposed animals were mixed in terms of age (12- to 26-week old) and gender, while those differences were not taken into account in the analysis. Moreover, other groups have published contradictory results (3). Our group undertook a confirmation study of the Salford experiments within an international collaborative programme including technical improvements. Our study includes the detection of dark neurons, alteration of the permeability of the BBB and apoptosis 14 or 50 days after GSM-900 exposure. The exposure setup was the loop antenna that allows for head-only exposure. Five groups of 16 Fisher 344 rats (14 -week old) were exposed to GSM-900 during 2 hours at various SAR levels (0, 0.14 and 2.0 W/kg), or were used as cage control or positive controls. Positive controls were treated with kainic acid (10 mg/kg) or by cold injury (dry ice during 5 minutes). After exposure, rats were kept alive during 14 or 50 days to study brain damages. Then, they were anesthetized with urethane (i.p. 1.5 mg/kg), perfused with PBS and fixed with paraformaldehyde 4% (PAF 4%). Brains were extracted and put in cold PAF 4% during the following night, then placed in cold sucrose 20% during 2-3 days, frozen with isopentane and placed at -80 deg. C. Coding was done on brains. Frozen brains were cut in 3

  4. Radiofrequency field emitted by mobile phones and alteration of the blood-brain barrier: how strong is the experimental evidence?

    Lagroye, I.; Haro, E.; Billaudel, B.; Ruffie, G.; Poulletier de Gannes, F.; Taxile, M.; Laclau, M.; Veyret, B. [PIOM/UMR 5501 and Bioelectromagnetics laboratory/EPHE, ENSCPB, 33607 Pessac, (France); Leveque, P. [IRCOM, CNRS UMR 6615, Limoges (France)

    2006-07-01

    Full text of publication follows: It is known that high power, thermal radiofrequency radiation (RFR) can alter the blood-brain barrier (BBB) permeability with a brain averaged specific absorption rate (BASAR) threshold evaluated at around 100 W/kg (1). Mobile communication technologies are using RFR with exposure guidelines for public local exposure at 2 W/kg, far lower than the threshold previously mentioned. However, in a paper recently published (2) the occurrence of BBB leakage and brain damage (presence of dark neurons) has been reported 50 days after a single 2-hour exposure of rats to a GSM-900 signal. In that investigation however, bias could have occurred as, for instance, exposed animals were mixed in terms of age (12- to 26-week old) and gender, while those differences were not taken into account in the analysis. Moreover, other groups have published contradictory results (3). Our group undertook a confirmation study of the Salford experiments within an international collaborative programme including technical improvements. Our study includes the detection of dark neurons, alteration of the permeability of the BBB and apoptosis 14 or 50 days after GSM-900 exposure. The exposure setup was the loop antenna that allows for head-only exposure. Five groups of 16 Fisher 344 rats (14 -week old) were exposed to GSM-900 during 2 hours at various SAR levels (0, 0.14 and 2.0 W/kg), or were used as cage control or positive controls. Positive controls were treated with kainic acid (10 mg/kg) or by cold injury (dry ice during 5 minutes). After exposure, rats were kept alive during 14 or 50 days to study brain damages. Then, they were anesthetized with urethane (i.p. 1.5 mg/kg), perfused with PBS and fixed with paraformaldehyde 4% (PAF 4%). Brains were extracted and put in cold PAF 4% during the following night, then placed in cold sucrose 20% during 2-3 days, frozen with isopentane and placed at -80 deg. C. Coding was done on brains. Frozen brains were cut in 3

  5. Filters for mobile radio from high Tc ceramic superconductors

    Peterson, G.E.; Wong, E.; Alford, N.McN.

    1990-01-01

    Mobile radio frequencies lie between 30 MHz and 1,000 MHz. This frequency range is ideal for ceramic high T c superconductors. We have designed Chebyshev, Butterworth and interdigital filters that can employ high T c superconductors in the form of rods, tubes and helices. In general, the performance of these filters at milliwatt power levels is excellent. We will describe fabrication of the superconductors and filter design

  6. Creating Live Interactions to Mitigate Barriers (CLIMB): A Mobile Intervention to Improve Social Functioning in People With Chronic Psychotic Disorders

    Schlosser, Danielle; Nahum, Mor

    2016-01-01

    Background Numerous psychosocial interventions for individuals with chronic psychotic disorders (CPD) have shown positive effects on social cognitive and functional outcome measures. However, access to and engagement with these interventions remains limited. This is partly because these interventions require specially trained therapists, are not available in all clinical settings, and have a high scheduling burden for participants, usually requiring a commitment of several weeks. Delivering interventions remotely via mobile devices may facilitate access, improve scheduling flexibility, and decrease participant burden, thus improving adherence to intervention requirements. To address these needs, we designed the Creating Live Interactions to Mitigate Barriers (CLIMB) digital intervention, which aims to enhance social functioning in people with CPD. CLIMB consists of two treatment components: a computerized social cognition training (SCT) program and optimized remote group therapy (ORGT). ORGT is an innovative treatment that combines remote group therapy with group texting (short message service, SMS). Objectives The objectives of this single-arm study were to investigate the feasibility of delivering 6 weeks of CLIMB to people with CPD and explore the initial effects on outcomes. Methods Participants were recruited, screened and enrolled via the Internet, and delivered assessments and interventions remotely using provided tablets (iPads). Participants were asked to complete 18 hours of SCT and to attend 6 remote group therapy sessions. To assess feasibility, adherence to study procedures, attrition rates, engagement metrics, and acceptability of the intervention were evaluated. Changes on measures of social cognition, quality of life, and symptoms were also explored. Results In total, 27 participants were enrolled over 12 months. Remote assessments were completed successfully on 96% (26/27) of the enrolled participants. Retention in the 6-week trial was 78% (21

  7. High mobility ZnO nanowires for terahertz detection applications

    Liu, Huiqiang; Peng, Rufang; Chu, Shijin; Chu, Sheng

    2014-01-01

    An oxide nanowire material was utilized for terahertz detection purpose. High quality ZnO nanowires were synthesized and field-effect transistors were fabricated. Electrical transport measurements demonstrated the nanowire with good transfer characteristics and fairly high electron mobility. It is shown that ZnO nanowires can be used as building blocks for the realization of terahertz detectors based on a one-dimensional plasmon detection configuration. Clear terahertz wave (∼0.3 THz) induced photovoltages were obtained at room temperature with varying incidence intensities. Further analysis showed that the terahertz photoresponse is closely related to the high electron mobility of the ZnO nanowire sample, which suggests that oxide nanoelectronics may find useful terahertz applications.

  8. Reducing barriers to healthy weight: Planned and responsive adaptations to a lifestyle intervention to serve people with impaired mobility.

    Betts, Andrea C; Froehlich-Grobe, Katherine; Driver, Simon; Carlton, Danielle; Kramer, M Kaye

    2018-04-01

    People with impaired mobility (IM) disabilities have a higher prevalence of obesity and obesity-related chronic conditions; however, lifestyle interventions that address the unique needs of people with IM are lacking. This paper describes an adapted evidence-based lifestyle intervention developed through community-based participatory research (CBPR). Individuals with IM, health professionals, disability group representatives, and researchers formed an advisory board to guide the process of thoroughly adapting the Diabetes Prevention Program Group Lifestyle Balance (DPP GLB) intervention after a successful pilot in people with IM. The process involved two phases: 1) planned adaptations to DPP GLB content and delivery, and 2) responsive adaptations to address issues that emerged during intervention delivery. Planned adaptations included combining in-person sessions with conference calls, providing arm-based activity trackers, and adding content on adaptive cooking, adaptive physical activity, injury prevention, unique health considerations, self-advocacy, and caregiver support. During the intervention, participants encountered numerous barriers, including health and mental health issues, transportation, caregivers, employment, adjusting to disability, and functional limitations. We addressed barriers with responsive adaptations, such as supporting electronic self-monitoring, offering make up sessions, and adding content and activities on goal setting, problem solving, planning, peer support, reflection, and motivation. Given the lack of evidence on lifestyle change in people with disabilities, it is critical to involve the community in intervention planning and respond to real-time barriers as participants engage in change. A randomized controlled trial (RCT) is underway to examine the usability, feasibility, and preliminary effectiveness of the adapted intervention. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Fish movement ecology in high gradient headwater streams: Its relevance to fish passage restoration through stream culvert barriers

    Hoffman, Robert L.; Dunham, Jason B.

    2007-01-01

    Restoration of fish passage through culvert barriers has emerged as a major issue in the Pacific Northwest and nationwide, in part, because of their potential influence on fish movement. Movement is an essential mechanism by which mobile animals acquire the resources necessary for the successful completion of their life-cycles. In this report, we provide a brief review of some essential characteristics of animal movement and examples from a focal group of fishes in Washington State: salmon, trout, and char. We begin by outlining some basic characteristics of animal movement and then apply that foundation to the case of salmonid fishes. Next we consider the consequences of disrupting fish movement with human-constructed barriers, such as culverts. Finally, this body of evidence is summarized, and we propose a short list of what we view as high priority information needs to support more effective restoration of fish passage through culverts.

  10. Mobile marketing for mobile games

    Vu, Giang

    2016-01-01

    Highly developed mobile technology and devices enable the rise of mobile game industry and mobile marketing. Hence mobile marketing for mobile game is an essential key for a mobile game success. Even though there are many articles on marketing for mobile games, there is a need of highly understanding mobile marketing strategies, how to launch a mobile campaign for a mobile game. Besides that, it is essential to understand the relationship between mobile advertising and users behaviours. There...

  11. Barriers to Career Mobility/Advancement by African-American and Caucasian Female Administrators in Minnesota Organizations: A Perception or Reality?

    Coleman, Jo Evans

    The primary purpose of this research was to identify perceived barriers affecting African-American and Caucasian female administrators' career mobility/advancement in education, business/industry, and government in Minnesota. The study explored women's perceptions of the effects that race/gender discrimination and gender underrepresentation have…

  12. Kinase detection with gallium nitride based high electron mobility transistors.

    Makowski, Matthew S; Bryan, Isaac; Sitar, Zlatko; Arellano, Consuelo; Xie, Jinqiao; Collazo, Ramon; Ivanisevic, Albena

    2013-07-01

    A label-free kinase detection system was fabricated by the adsorption of gold nanoparticles functionalized with kinase inhibitor onto AlGaN/GaN high electron mobility transistors (HEMTs). The HEMTs were operated near threshold voltage due to the greatest sensitivity in this operational region. The Au NP/HEMT biosensor system electrically detected 1 pM SRC kinase in ionic solutions. These results are pertinent to drug development applications associated with kinase sensing.

  13. Ultimate response time of high electron mobility transistors

    Rudin, Sergey; Rupper, Greg; Shur, Michael

    2015-01-01

    We present theoretical studies of the response time of the two-dimensional gated electron gas to femtosecond pulses. Our hydrodynamic simulations show that the device response to a short pulse or a step-function signal is either smooth or oscillating time-decay at low and high mobility, μ, values, respectively. At small gate voltage swings, U 0  = U g  − U th , where U g is the gate voltage and U th is the threshold voltage, such that μU 0 /L < v s , where L is the channel length and v s is the effective electron saturation velocity, the decay time in the low mobility samples is on the order of L 2 /(μU 0 ), in agreement with the analytical drift model. However, the decay is preceded by a delay time on the order of L/s, where s is the plasma wave velocity. This delay is the ballistic transport signature in collision-dominated devices, which becomes important during very short time periods. In the high mobility devices, the period of the decaying oscillations is on the order of the plasma wave velocity transit time. Our analysis shows that short channel field effect transistors operating in the plasmonic regime can meet the requirements for applications as terahertz detectors, mixers, delay lines, and phase shifters in ultra high-speed wireless communication circuits

  14. Older adults are mobile too!Identifying the barriers and facilitators to older adults' use of mHealth for pain management.

    Parker, Samantha J; Jessel, Sonal; Richardson, Joshua E; Reid, M Cary

    2013-05-06

    Mobile health (mHealth) is a rapidly emerging field with the potential to assist older adults in the management of chronic pain (CP) through enhanced communication with providers, monitoring treatment-related side effects and pain levels, and increased access to pain care resources. Little is currently known, however, about older adults' attitudes and perceptions of mHealth or perceived barriers and facilitators to using mHealth tools to improve pain management. We conducted six focus groups comprised of 41 diverse older adults (≥60 years of age) with CP. Participants were recruited from one primary care practice and two multiservice senior community day-visit centers located in New York City that serve older adults in their surrounding neighborhoods. Focus group discussions were recorded and transcribed, and transcriptions were analyzed using direct content analysis to identify and quantify themes. Focus group discussions generated 38 individual themes pertaining to the use of mHealth to help manage pain and pain medications. Participants had low prior use of mHealth (5% of participants), but the vast majority (85%) were highly willing to try the devices. Participants reported that mHealth devices might help them reach their healthcare provider more expeditiously (27%), as well as help to monitor for falls and other adverse events in the home (15%). Barriers to device use included concerns about the cost (42%) and a lack of familiarity with the technology (32%). Facilitators to device use included training prior to device use (61%) and tailoring devices to the functional needs of older adults (34%). This study suggests that older adults with CP are interested and willing to use mHealth to assist in the management of pain. Participants in our study reported important barriers that medical professionals, researchers, and mHealth developers should address to help facilitate the development and evaluation of age-appropriate, and function-appropriate, m

  15. High density internal transport barriers for burning plasma operation

    Ridolfini, V Pericoli [Associazione EURATOM-ENEA sulla Fusione, CR Frascati, Rome (Italy); Barbato, E [Associazione EURATOM-ENEA sulla Fusione, CR Frascati, Rome (Italy); Buratti, P [Associazione EURATOM-ENEA sulla Fusione, CR Frascati, Rome (Italy)] (and others)

    2005-12-15

    A tokamak plasma with internal transport barriers (ITBs) is the best candidate for a steady ITER operation, since the high energy confinement allows working at plasma currents (I{sub p}) lower than the reference scenario. To build and sustain an ITB at the ITER high density ({>=}10{sup 20} m{sup -3}) and largely dominant electron (e{sup -}) heating is not trivial in most existing tokamaks. FTU can instead meet both requests, thanks to its radiofrequency heating systems, lower hybrid (LH, up to 1.9 MW) and electron cyclotron (EC up to 1.2 MW). By the combined use of them, ITBs are obtained up to peak densities n{sub e0} > 1.3 x 10{sup 20} m{sup -3}, with central e{sup -} temperatures T{sub e0} {approx} 5.5 keV, and are sustained for as long as the heating pulse is applied (>35 confinement times, {tau}{sub E}). At n{sub e0} {approx} 0.8 x 10{sup 20} m{sup -3} T{sub e0} can be larger than 11 keV. Almost full current drive (CD) and an overall good steadiness is attained within about one {tau}{sub E}, 20 times faster than the ohmic current relaxation time. The ITB extends over a central region with an almost flat or slightly reversed q profile and q{sub min} {approx} 1.3 that is fully sustained by off-axis lower hybrid current drive. Consequent to this is the beneficial good alignment of the bootstrap current, generated by the ITB large pressure gradients, with the LH driven current. Reflectometry shows a clear change in the turbulence close to the ITB radius, consistent with the reduced e{sup -} transport. Ions (i{sup +}) are significantly heated via collisions, but thermal equilibrium with electrons cannot be attained since the e{sup -}-i{sup +} equipartition time is always 4-5 times longer than {tau}{sub E}. No degradation of the overall ion transport, rather a reduction of the i{sup +} heat diffusivity, is observed inside the ITB. The global confinement has been improved up to 1.6 times over the scaling predictions. The ITB radius can be controlled by adjusting the

  16. From barriers to bridges: An investigation on Saudi student mobility (2006-2009)

    Denman, Brian D.; Hilal, Kholoud T.

    2011-08-01

    Globalisation is often thought to advocate for a single set of beliefs and customs and for a rejection of the need to protect regional cultures and traditions. In the aftermath of 9/11, the rift between Western and Arab cultures has deepened, and there is a patent need for cultural bridges to be built. The government of Saudi Arabia has, by increasing funding for higher education through grants and scholarships, enabled Saudi students to study at overseas universities. A number of non-Saudi students are also enrolled at Saudi Arabian universities. After a brief introduction to the cultural and educational history of the Arab region and Saudi identity, this article turns to contemporary higher education in Saudi Arabia. It introduces the King Abdullah Scholarship Programme and then goes on to present detailed enrolment data for 2006-2009, demonstrating trends and policy changes and identifying patterns in student mobility.

  17. Mapping barriers and intervention activities to behaviour change theory for Mobilization of Vulnerable Elders in Ontario (MOVE ON), a multi-site implementation intervention in acute care hospitals.

    Moore, Julia E; Mascarenhas, Alekhya; Marquez, Christine; Almaawiy, Ummukulthum; Chan, Wai-Hin; D'Souza, Jennifer; Liu, Barbara; Straus, Sharon E

    2014-10-30

    As evidence-informed implementation interventions spread, they need to be tailored to address the unique needs of each setting, and this process should be well documented to facilitate replication. To facilitate the spread of the Mobilization of Vulnerable Elders in Ontario (MOVE ON) intervention, the aim of the current study is to develop a mapping guide that links identified barriers and intervention activities to behaviour change theory. Focus groups were conducted with front line health-care professionals to identify perceived barriers to implementation of an early mobilization intervention targeted to hospitalized older adults. Participating units then used or adapted intervention activities from an existing menu or developed new activities to facilitate early mobilization. A thematic analysis was performed on the focus group data, emphasizing concepts related to barriers to behaviour change. A behaviour change theory, the 'capability, opportunity, motivation-behaviour (COM-B) system', was used as a taxonomy to map the identified barriers to their root causes. We also mapped the behaviour constructs and intervention activities to overcome these. A total of 46 focus groups were conducted across 26 hospital inpatient units in Ontario, Canada, with 261 participants. The barriers were conceptualized at three levels: health-care provider (HCP), patient, and unit. Commonly mentioned barriers were time constraints and workload (HCP), patient clinical acuity and their perceived 'sick role' (patient), and lack of proper equipment and human resources (unit level). Thirty intervention activities to facilitate early mobilization of older adults were implemented across hospitals; examples of unit-developed intervention activities include the 'mobility clock' communication tool and the use of staff champions. A mapping guide was created with barriers and intervention activities matched though the lens of the COM-B system. We used a systematic approach to develop a guide

  18. Mobile Sensing Systems

    Macias, Elsa; Suarez, Alvaro; Lloret, Jaime

    2013-01-01

    Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high. PMID:24351637

  19. Mobile sensing systems.

    Macias, Elsa; Suarez, Alvaro; Lloret, Jaime

    2013-12-16

    Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high.

  20. Mobile Sensing Systems

    Elsa Macias

    2013-12-01

    Full Text Available Rich-sensor smart phones have made possible the recent birth of the mobile sensing research area as part of ubiquitous sensing which integrates other areas such as wireless sensor networks and web sensing. There are several types of mobile sensing: individual, participatory, opportunistic, crowd, social, etc. The object of sensing can be people-centered or environment-centered. The sensing domain can be home, urban, vehicular… Currently there are barriers that limit the social acceptance of mobile sensing systems. Examples of social barriers are privacy concerns, restrictive laws in some countries and the absence of economic incentives that might encourage people to participate in a sensing campaign. Several technical barriers are phone energy savings and the variety of sensors and software for their management. Some existing surveys partially tackle the topic of mobile sensing systems. Published papers theoretically or partially solve the above barriers. We complete the above surveys with new works, review the barriers of mobile sensing systems and propose some ideas for efficiently implementing sensing, fusion, learning, security, privacy and energy saving for any type of mobile sensing system, and propose several realistic research challenges. The main objective is to reduce the learning curve in mobile sensing systems where the complexity is very high.

  1. Japanese high school students' usage of mobile phones while cycling.

    Ichikawa, Masao; Nakahara, Shinji

    2008-03-01

    To investigate the perception and actual use of mobile phones among Japanese high school students while riding their bicycles, and their experience of bicycle crash/near-crash. A questionnaire survey was carried out at high schools that were, at the time of the survey, commissioned by the National Agency for the Advancement of Sports and Health to conduct school safety research. In the survey, we found that mobile phone use while riding a bicycle was quite common among the students during their commute, but those who have a higher perception of danger in this practice, and those who perceived that this practice is prohibited, were less likely to engage in this practice. Male students and students commuting to school by bicycle only were more likely to have used phones while riding. There was a significant relationship between phone usage while riding a bicycle and the experience of bicycle crash/near-crash, although its causality was not established. Bicycle crash/near-crash experienced while using a phone was less prevalent among the students who had a higher perception of danger in phone usage while riding, students who perceived that this practice is prohibited, and students with a shorter travel time by bicycle during the commute. Since mobile phone use while riding a bicycle potentially increases crash risk among cyclists, student bicycle commuters should be made aware of this risk. Moreover, they should be informed that cyclists' phone usage while riding is prohibited according to the road traffic law.

  2. Mobile learning and high-lighting language education

    Vinther, Jane

    Mobile learning and high-profiling language education. The number of students learning a second or foreign language and participating in instruction in languages other than English has been in decline for some time. There seems to be such a general tendency across nations albeit for a variety...... of reasons idiosyncratic to the particular national conditions. This paper gives an account of a diversified national project designed to infuse foreign language learning classes in upper secondary schools in Denmark with renewed enthusiasm through systematically experimenting with the new media by taking...... advantage of the social side in their application. The aim has been to make language classes attractive and relevant and to highlight the attractiveness and fun in learning through web 2.0 and mobile units. The overall project was supported by the Danish ministry of education as well as the individual...

  3. Sows with high milk production had both a high feed intake and high body mobilization

    Strathe, A. V.; Bruun, T. S.; Hansen, C. F.

    2017-01-01

    Selection for increased litter size have generated hyper-prolific sows that nurses large litters, however limited knowledge is available regarding the connection between milk production, feed intake and body mobilization of these modern sows. The aim of the current study was to determine what...... be explained by a relatively higher proportion of their body reserves being mobilized compared with multiparous sows. The ADG of the litter was positively related by ADFI of the sows, litter size and BW loss and increasing the ADFI with 1 kg/day throughout lactation likely increased the ADG of the litter...... characterized sows with high milk production and nursing large litters, differences between sows of different parities and effects of lactational performance on next reproductive cycle. In total 565 sows (parity 1 to 4) were studied from 7 days before farrowing until weaning. On day 2 postpartum litters were...

  4. Temperature dependence of ballistic mobility in a metamorphic InGaAs/InAlAs high electron mobility transistor

    Lee, Jongkyong; Gang, Suhyun; Jo, Yongcheol; Kim, Jongmin; Woo, Hyeonseok; Han, Jaeseok; Kim, Hyungsang; Im, Hyunsik

    2014-01-01

    We have investigated the temperature dependence of ballistic mobility in a 100 nm-long InGaAs/InAlAs metamorphic high-electron-mobility transistor designed for millimeter-wavelength RF applications. To extract the temperature dependence of quasi-ballistic mobility, our experiment involves measurements of the effective mobility in the low-bias linear region of the transistor and of the collision-dominated Hall mobility using a gated Hall bar of the same epitaxial structure. The data measured from the experiment are consistent with that of modeled ballistic mobility based on ballistic transport theory. These results advance the understanding of ballistic transport in various transistors with a nano-scale channel length that is comparable to the carrier's mean free path in the channel.

  5. Perceived environmental barriers to outdoor mobility and changes in sense of autonomy in participation outdoors among older people: a prospective two-year cohort study.

    Rantakokko, Merja; Portegijs, Erja; Viljanen, Anne; Iwarsson, Susanne; Kauppinen, Markku; Rantanen, Taina

    2017-08-01

    The aim was to study whether perceived environmental barriers to outdoor mobility affect changes in sense of autonomy in participation outdoors among community-dwelling older people over a two-year period. Community-dwelling people aged 75-90 years (n = 848) in central Finland were interviewed on two occasions, face-to-face at baseline and over the telephone two years later. Perceived environmental barriers to outdoor mobility were assessed using a 15-item structured questionnaire, and the sum scores categorized into tertiles (0, 1 and 2 or more barriers). Autonomy in participation outdoors was assessed with the 'Impact on Participation and Autonomy' (IPA) questionnaire using the autonomy outdoors subscale (score range 0-20, higher scores indicating more restricted autonomy). Scores for autonomy in participation outdoors were available for 848 participants at baseline (mean 6.2, SD = 3.8) and for 748 participants at the two-year follow-up (mean 6.7, SD = 3.9). At baseline, those reporting multiple environmental barriers had the most restricted autonomy, while those reporting no environmental barriers had the least restricted autonomy (p autonomy in participation outdoors declined more among those reporting multiple environmental barriers compared to those reporting none (age- and sex-adjusted group*time β = .629, s.e. = .277, p = .023). Adjustment for cognitive functioning, education, number of chronic conditions and change in walking difficulty did not influence the association. Perceived environmental barriers to outdoor mobility accelerate the decline in autonomy in participation outdoors among older community-dwelling people. Understanding factors affecting autonomy can help in finding ways to support the sense of autonomy as people age.

  6. High density internal transport barriers for burning plasma operation

    Pericoli Ridolfini, V.

    2005-01-01

    One of the proposed ITER scenarios foresees the creation and sustainment of an internal transport barrier (ITB) in order to improve the confinement properties of the hot core plasma. The more stringent requests are: the ITB must be sustained with electron heating only with no or very small external momentum source, the strong collisional coupling at the envisaged density (line average >1.0 1020 m-3) must not prevent the barrier existence, the bootstrap current created by the large induced gradients must have a radial profile consistent with that requested by the barrier creation and sustainment. To all these items the studies carried out in FTU in the same density range (ne0 ?1.5 1020 m-3) provide encouraging prospects. With pure electron heating and current drive (LH+ECH) steady electron barrier are generated and maintained with central e- temperature >5.0 keV. Almost full CD conditions are established with a bootstrap current close to 25% of the total and well aligned with that driven by the LH waves and responsible for the barrier building. The clear change in the density fluctuations close to the ITB radius, observed by reflectometry, indicates stabilization of turbulence that is consistent with the drop of the thermal electron diffusivity inside the ITB to very low values, ?e<0.5 m2/s estimated by the transport analysis. The 10 fold neutron rate increase testifies a significant collisional ion heating, even though usually ?Ti0/Ti0 does not exceed 40%, because the e--i + equipartition time, always 4-5 times longer than the energy confinement time, does not allow thermal equilibrium with electrons to be attained. The ion thermal diffusivity inside the barrier must be lowered to the neoclassical level to account for the observed Ti(r) profiles, clearly indicating at least a non-degraded ion transport. The global confinement in turn improves by 1.6 times above the FTU L-scaling. The ITB radius can be controlled by varying the LH power deposition profile that is

  7. Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

    Ilke Uysal Unalan

    2016-12-01

    Full Text Available In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate (PET with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO were used as main polymer phase and nanobuilding block (NBB, respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ and as a function of different relative humidity (RH values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1 value below the detection limit of the instrument (0.01 mL·m−2·24 h−1 was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films. Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03. The mechanisms underlying the experimental observations are discussed.

  8. ANALYSIS OF BARRIERS IN LISTENING COMPREHENSION AMONG JUNIOR HIGH SCHOOL STUDENTS

    Setia Muljanto

    2012-12-01

    Full Text Available This research paper identifies barriers and difficulties in listening comprehension faced by junior high school students. The research questions were what barriers did students encounter and how did they used strategies to overcome those barriers. This study used a qualitative method and was a case study involving 40 students and one English teacher. The data were obtained by ways of conducting a test of listening taken from TOEIC test. The tests indicated that the results scores were not quite satisfactory. This is primarily caused by speech delivery of the native speaker which was too fast. This means that students faced listening barriers especially in processing information. The data also indicated that students were also nervous when doing the test as habitual barrier. Strategies used to overcome these barriers are by making students get used to listen and use English and making them familiar with certain contexts in real life.

  9. Gravel Mobility in a High Sand Content Riverbed

    Haschenburger, J. K.

    2017-12-01

    In sand-gravel channels, sand may modify gravel transport by changing conditions of entrainment and promoting longer displacements or gravel may inhibit sand transport if concentrated into distinct deposits, which restrict sand supply with consequences for migrating bedform size or form. This study reports on gravel mobility in the lower San Antonio River, Texas, where gravel content in the bed material ranges from about 1% to more than 20%. Sediment transport observations were collected at three U.S. Geological Survey gauging stations by deploying a Helley-Smith sampler with a 0.2 mm mesh bag from which transport rates and mobile grain sizes were determined. The flow rates sampled translate into an annual exceedance expectation from 0.2% to 98%. Gravel transport rates are generally two orders of magnitude smaller than the rates of sand transport. However, the finest gravels are transported at rates on the same order of magnitude as the coarsest sands. At all sites, the 2 and 2.8 mm fractions are transported at the lowest flow rate sampled, suggesting mobility for at least 38% to as much as 98% of the year. Fractions as large as 8 mm are mobilized at flow rates that are expected between 25% and 53% of the year. The largest fractions captured in the sampling (16 to 32 mm) require flows closer to bankfull conditions that occur no more than 0.8% of the year. Results document that some gravel sizes can be frequently transported in low gradient riverbeds with high sand content.

  10. Physical activity in patients with type 2 diabetes and hypertension – insights into motivations and barriers from the MOBILE study

    Duclos M

    2015-06-01

    International Physical Activity Questionnaire (59.5% vs 9.6%. Target control was achieved by 33% of active and 19% of inactive patients (P<0.001. Active patients, those with fewer barriers to PA, with lower treatment burden, and with an active physician, were more likely to reach targets. The physician’s role emerged in the motivations (reassurance on health issues, training on hypoglycemia risk, and prescription/monitoring of the PA by the physician. A negative self-image was the highest ranked barrier for the inactive patients, followed by lack of support and medical concerns. Conclusion: Physicians should consider PA prescription as seriously as any drug prescription, and take into account motivations and barriers to PA to tailor advice to patients' specific needs and reduce their perceived constraints. Keywords: physical activity, type 2 diabetes, hypertension, motivations, barriers, MOBILE

  11. Photo-Detection on Narrow-Bandgap High-Mobility 2D Semiconductors

    Charnas, Adam; Qiu, Gang; Deng, Yexin; Wang, Yixiu; Du, Yuchen; Yang, Lingming; Wu, Wenzhuo; Ye, Peide

    Photo-detection and energy harvesting device concepts have been demonstrated widely in 2D materials such as graphene, TMDs, and black phosphorus. In this work, we demonstrate anisotropic photo-detection achieved using devices fabricated from hydrothermally grown narrow-bandgap high-mobility 2D semiconductor. Back-gated FETs were fabricated by transferring the 2D flakes onto a Si/SiO2 substrate and depositing various metal contacts across the flakes to optimize the access resistance for optoelectronic devices. Photo-responsivity was measured and mapped by slightly biasing the devices and shining a laser spot at different locations of the device to observe and map the resulting photo-generated current. Optimization of the Schottky barrier height for both n and p at the metal-2D interfaces using asymmetric contact engineering was performed to improve device performance.

  12. High electron mobility in Ga(In)NAs films grown by molecular beam epitaxy

    Miyashita, Naoya; Ahsan, Nazmul; Monirul Islam, Muhammad; Okada, Yoshitaka; Inagaki, Makoto; Yamaguchi, Masafumi

    2012-01-01

    We report the highest mobility values above 2000 cm 2 /Vs in Si doped GaNAs film grown by molecular beam epitaxy. To understand the feature of the origin which limits the electron mobility in GaNAs, temperature dependences of mobility were measured for high mobility GaNAs and referential low mobility GaInNAs. Temperature dependent mobility for high mobility GaNAs is similar to the GaAs case, while that for low mobility GaInNAs shows large decrease in lower temperature region. The electron mobility of high quality GaNAs can be explained by intrinsic limiting factor of random alloy scattering and extrinsic factor of ionized impurity scattering.

  13. Identifying Barriers to Delivering the Awakening and Breathing Coordination, Delirium, and Early Exercise/Mobility Bundle to Minimize Adverse Outcomes for Mechanically Ventilated Patients: A Systematic Review.

    Costa, Deena Kelly; White, Matthew R; Ginier, Emily; Manojlovich, Milisa; Govindan, Sushant; Iwashyna, Theodore J; Sales, Anne E

    2017-08-01

    Improved outcomes are associated with the Awakening and Breathing Coordination, Delirium, and Early exercise/mobility bundle (ABCDE); however, implementation issues are common. As yet, no study has integrated the barriers to ABCDE to provide an overview of reasons for less successful efforts. The purpose of this review was to identify and catalog the barriers to ABCDE delivery based on a widely used implementation framework, and to provide a resource to guide clinicians in overcoming barriers to implementation. We searched MEDLINE via PubMed, CINAHL, and Scopus for original research articles from January 1, 2007, to August 31, 2016, that identified barriers to ABCDE implementation for adult patients in the ICU. Two reviewers independently reviewed studies, extracted barriers, and conducted thematic content analysis of the barriers, guided by the Consolidated Framework for Implementation Research. Discrepancies were discussed, and consensus was achieved. Our electronic search yielded 1,908 articles. After applying our inclusion/exclusion criteria, we included 49 studies. We conducted thematic content analysis of the 107 barriers and identified four classes of ABCDE barriers: (1) patient-related (ie, patient instability and safety concerns); (2) clinician-related (ie, lack of knowledge, staff safety concerns); (3) protocol-related (ie, unclear protocol criteria, cumbersome protocols to use); and, not previously identified in past reviews, (4) ICU contextual barriers (ie, interprofessional team care coordination). We provide the first, to our knowledge, systematic differential diagnosis of barriers to ABCDE delivery, moving beyond the conventional focus on patient-level factors. Our analysis offers a differential diagnosis checklist for clinicians planning ABCDE implementation to improve patient care and outcomes. Copyright © 2017 American College of Chest Physicians. All rights reserved.

  14. High density high performance plasma with internal diffusion barrier in Large Helical Device

    Sakamoto, R.; Kobayashi, M.; Miyazawa, J.

    2008-10-01

    A attractive high density plasma operational regime, namely an internal diffusion barrier (IDB), has been discovered in the intrinsic helical divertor configuration on the Large Helical Device (LHD). The IDB which enables core plasma to access a high density/high pressure regime has been developed. It is revealed that the IDB is reproducibly formed by pellet fueling in the magnetic configurations shifted outward in major radius. Attainable central plasma density exceeds 1x10 21 m -3 . Central pressure reaches 1.5 times atmospheric pressure and the central β value becomes fairly high even at high magnetic field, i.e. β(0)=5.5% at B t =2.57 T. (author)

  15. High-mobility ultrathin semiconducting films prepared by spin coating.

    Mitzi, David B; Kosbar, Laura L; Murray, Conal E; Copel, Matthew; Afzali, Ali

    2004-03-18

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (approximately 50 A), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS(2-x)Se(x) films, which exhibit n-type transport, large current densities (>10(5) A cm(-2)) and mobilities greater than 10 cm2 V(-1) s(-1)--an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  16. High-mobility ultrathin semiconducting films prepared by spin coating

    Mitzi, David B.; Kosbar, Laura L.; Murray, Conal E.; Copel, Matthew; Afzali, Ali

    2004-03-01

    The ability to deposit and tailor reliable semiconducting films (with a particular recent emphasis on ultrathin systems) is indispensable for contemporary solid-state electronics. The search for thin-film semiconductors that provide simultaneously high carrier mobility and convenient solution-based deposition is also an important research direction, with the resulting expectations of new technologies (such as flexible or wearable computers, large-area high-resolution displays and electronic paper) and lower-cost device fabrication. Here we demonstrate a technique for spin coating ultrathin (~50Å), crystalline and continuous metal chalcogenide films, based on the low-temperature decomposition of highly soluble hydrazinium precursors. We fabricate thin-film field-effect transistors (TFTs) based on semiconducting SnS2-xSex films, which exhibit n-type transport, large current densities (>105Acm-2) and mobilities greater than 10cm2V-1s-1-an order of magnitude higher than previously reported values for spin-coated semiconductors. The spin-coating technique is expected to be applicable to a range of metal chalcogenides, particularly those based on main group metals, as well as for the fabrication of a variety of thin-film-based devices (for example, solar cells, thermoelectrics and memory devices).

  17. Tuning on-off current ratio and field-effect mobility in a MoS(2)-graphene heterostructure via Schottky barrier modulation.

    Shih, Chih-Jen; Wang, Qing Hua; Son, Youngwoo; Jin, Zhong; Blankschtein, Daniel; Strano, Michael S

    2014-06-24

    Field-effect transistor (FET) devices composed of a MoS2-graphene heterostructure can combine the advantages of high carrier mobility in graphene with the permanent band gap of MoS2 for digital applications. Herein, we investigate the electron transfer, photoluminescence, and gate-controlled carrier transport in such a heterostructure. We show that the junction is a Schottky barrier, whose height can be artificially controlled by gating or doping graphene. When the applied gate voltage (or the doping level) is zero, the photoexcited electron-hole pairs in monolayer MoS2 can be split by the heterojunction, significantly reducing the photoluminescence. By applying negative gate voltage (or p-doping) in graphene, the interlayer impedance formed between MoS2 and graphene exhibits an 100-fold increase. For the first time, we show that the gate-controlled interlayer Schottky impedance can be utilized to modulate carrier transport in graphene, significantly depleting the hole transport, but preserving the electron transport. Accordingly, we demonstrate a new type of FET device, which enables a controllable transition from NMOS digital to bipolar characteristics. In the NMOS digital regime, we report a very high room temperature on/off current ratio (ION/IOFF ∼ 36) in comparison to graphene-based FET devices without sacrificing the field-effect electron mobilities in graphene. By engineering the source/drain contact area, we further estimate that a higher value of ION/IOFF up to 100 can be obtained in the device architecture considered. The device architecture presented here may enable semiconducting behavior in graphene for digital and analogue electronics.

  18. High efficiency combined heat and power facilities - benefits and barriers

    Klein, M.

    2001-01-01

    There are important linkages between the economy, energy production, the environment and our health. Where thermal energy is needed, distributed Combined Heat and Power facilities, using gas turbines, reciprocating engines and future fuel cells can provide significant improvements to our long term mix of energy production. Local generation can also have benefits in security of energy supply and economic savings. This paper is intended to discuss the relevant air pollution and greenhouse gas emissions from modem CHP plants, the emission prevention and reduction methods available, and their operating experience and cost-effectiveness. Mention is made of recently constructed industrial and commercial plants, and institutional barriers to further development. Solutions described for these barriers include the need for more awareness of opportunities, improved access to the electricity grid, the proper design balance between thermal and electric for CHP systems rather than large combined cycles, improved corporate taxation incentives, and the assessment of all environmental and economic benefits when considering such cleaner sources in a restructured energy market. (author)

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

    An-Jye Tzou

    2016-06-01

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

  20. One-to-One Mobile Technology in High School Physics Classrooms: Understanding Its Use and Outcome

    Zhai, Xiaoming; Zhang, Meilan; Li, Min

    2018-01-01

    This study examined ways in which high school students used mobile devices in physics classrooms and after school, and the impact of in-class and after-school mobile technology use on their physics learning performance and interest. We collected data from 803 high school freshmen in China after they had used mobile devices for over five months. A…

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

    Grady, R.; Bayram, C.

    2017-07-01

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

  2. Thermoelectric transport properties of high mobility organic semiconductors

    Venkateshvaran, Deepak; Broch, Katharina; Warwick, Chris N.; Sirringhaus, Henning

    2016-09-01

    Transport in organic semiconductors has traditionally been investigated using measurements of the temperature and gate voltage dependent mobility of charge carriers within the channel of organic field-effect transistors (OFETs). In such measurements, the behavior of charge carrier mobility with temperature and gate voltage, studied together with carrier activation energies, provide a metric to quantify the extent of disorder within these van der Waals bonded materials. In addition to the mobility and activation energy, another potent but often-overlooked transport coefficient useful in understanding disorder is the Seebeck coefficient (also known as thermoelectric power). Fundamentally, the Seebeck coefficient represents the entropy per charge carrier in the solid state, and thus proves powerful in distinguishing materials in which charge carriers move freely from those where a high degree of disorder causes the induced carriers to remain trapped. This paper briefly covers the recent highlights in the field of organic thermoelectrics, showing how significant strides have been made both from an applied standpoint as well as from a viewpoint of fundamental thermoelectric transport physics. It shall be illustrated how thermoelectric transport parameters in organic semiconductors can be tuned over a significant range, and how this tunability facilitates an enhanced performance for heat-to-electricity conversion as well as quantifies energetic disorder and the nature of the density of states (DOS). The work of the authors shall be spotlighted in this context, illustrating how Seebeck coefficient measurements in the polymer indacenodithiophene-co-benzothiadiazole (IDTBT) known for its ultra-low degree of torsion within the polymer backbone, has a trend consistent with low disorder. 1 Finally, using examples of the small molecules C8-BTBT and C10-DNTT, it shall be discussed how the Seebeck coefficient can aid the estimation of the density and distribution of trap states

  3. Efficient free energy calculations for compounds with multiple stable conformations separated by high energy barriers

    Hritz, J.; Oostenbrink, C.

    2009-01-01

    Compounds with high intramolecular energy barriers represent challenging targets for free energy calculations because of the difficulty to obtain sufficient conformational sampling. Existing approaches are therefore computationally very demanding, thus preventing practical applications for such

  4. One Component Encapsulating Material Matrix as High Barrier Coating, Phase I

    National Aeronautics and Space Administration — To address the NASA need for new flexible food packaging materials with effective high barrier against oxygen and moisture to protect food, minimize weight and...

  5. Charge fluctuations in high-electron-mobility transistors: a review

    Green, F.

    1993-01-01

    The quasi-two-dimensional carrier population, free to move within a near-perfect crystalline matrix, is the key to remarkable improvements in signal gain, current density and quiet operation. Current-fluctuation effects are central to all of these properties. Some of these are easily understood within linear-response theory, but other fluctuation phenomena are less tractable. In particular, nonequilibrium noise poses significant theoretical challenges, both descriptive and predictive. This paper examines a few of the basic physical issues which motivate device-noise theory. The structure and operation of high-electron-mobility transistor are first reviewed. The recent nonlinear fluctuation theory of Stanton and Wilkins (1987) help to identify at least some of the complicated noise physics which can arise when carriers in GaAs-like conduction bands are subjected to high fields. Simple examples of fluctuation-dominated behaviour are discussed, with numerical illustrations. 20 refs., 9 figs

  6. Design and simulation of a novel GaN based resonant tunneling high electron mobility transistor on a silicon substrate

    Chowdhury, Subhra; Biswas, Dhrubes; Chattaraj, Swarnabha

    2015-01-01

    For the first time, we have introduced a novel GaN based resonant tunneling high electron mobility transistor (RTHEMT) on a silicon substrate. A monolithically integrated GaN based inverted high electron mobility transistor (HEMT) and a resonant tunneling diode (RTD) are designed and simulated using the ATLAS simulator and MATLAB in this study. The 10% Al composition in the barrier layer of the GaN based RTD structure provides a peak-to-valley current ratio of 2.66 which controls the GaN based HEMT performance. Thus the results indicate an improvement in the current–voltage characteristics of the RTHEMT by controlling the gate voltage in this structure. The introduction of silicon as a substrate is a unique step taken by us for this type of RTHEMT structure. (paper)

  7. Balance the Carrier Mobility To Achieve High Performance Exciplex OLED Using a Triazine-Based Acceptor.

    Hung, Wen-Yi; Chiang, Pin-Yi; Lin, Shih-Wei; Tang, Wei-Chieh; Chen, Yi-Ting; Liu, Shih-Hung; Chou, Pi-Tai; Hung, Yi-Tzu; Wong, Ken-Tsung

    2016-02-01

    A star-shaped 1,3,5-triazine/cyano hybrid molecule CN-T2T was designed and synthesized as a new electron acceptor for efficient exciplex-based OLED emitter by mixing with a suitable electron donor (Tris-PCz). The CN-T2T/Tris-PCz exciplex emission shows a high ΦPL of 0.53 and a small ΔET-S = -0.59 kcal/mol, affording intrinsically efficient fluorescence and highly efficient exciton up-conversion. The large energy level offsets between Tris-PCz and CN-T2T and the balanced hole and electron mobility of Tris-PCz and CN-T2T, respectively, ensuring sufficient carrier density accumulated in the interface for efficient generation of exciplex excitons. Employing a facile device structure composed as ITO/4% ReO3:Tris-PCz (60 nm)/Tris-PCz (15 nm)/Tris-PCz:CN-T2T(1:1) (25 nm)/CN-T2T (50 nm)/Liq (0.5 nm)/Al (100 nm), in which the electron-hole capture is efficient without additional carrier injection barrier from donor (or acceptor) molecule and carriers mobilities are balanced in the emitting layer, leads to a highly efficient green exciplex OLED with external quantum efficiency (EQE) of 11.9%. The obtained EQE is 18% higher than that of a comparison device using an exciplex exhibiting a comparable ΦPL (0.50), in which TCTA shows similar energy levels but higher hole mobility as compared with Tris-PCz. Our results clearly indicate the significance of mobility balance in governing the efficiency of exciplex-based OLED. Exploiting the Tris-PCz:CN-T2T exciplex as the host, we further demonstrated highly efficient yellow and red fluorescent OLEDs by doping 1 wt % Rubrene and DCJTB as emitter, achieving high EQE of 6.9 and 9.7%, respectively.

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

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

    2015-01-01

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

  9. The Barriers to High-Quality Inpatient Pain Management: A Qualitative Study.

    Lin, Richard J; Reid, M Carrington; Liu, Lydia L; Chused, Amy E; Evans, Arthur T

    2015-09-01

    The current literature suggests deficiencies in the quality of acute pain management among general medical inpatients. The aim of this qualitative study is to identify potential barriers to high-quality acute pain management among general medical inpatients at an urban academic medical center during a 2-year period. Data are collected using retrospective chart reviews, survey questionnaires, and semistructured, open-ended interviews of 40 general medical inpatients who have experienced pain during their hospitalization. Our results confirm high prevalence and disabling impacts of pain and significant patient- and provider-related barriers to high-quality acute pain management. We also identify unique system-related barriers such as time delay and pain management culture. Efforts to improve the pain management experience of general medical inpatients will need to address all these barriers. © The Author(s) 2014.

  10. How Does School Mobility Impact Indicators of Academic Achievement for Highly Mobile Students?

    Tanner-McBrien, Laura

    2010-01-01

    Children who are homeless or in foster care change schools more often than their non-mobile peers. The impact of school mobility increases their risk of academic failure (Evans, 1996; Ingersoll, Scamman, & Eckerling, 1989; Mao, 1997, Mehana & Reynolds, 2003; Reynolds & Wolf, 1999). Laws enforcing the right of students to remain in…

  11. Project Guarantee 1985. Final repository for high-level radioactive wastes: The system of safety barriers

    Anon.

    1985-01-01

    Final disposal of radioactive waste involves preventing the waste from returning from the repository location into the biosphere by means of successively arranged containment measures known as safety barriers. In the present volume NGB 85-04 of the series of reports for Project 'Guarantee' 1985, the safety barrier system for the type C repository for high-level waste is described. The barrier parameters which are relevant for safety analysis are quantified and associated error limits and data scatter are given. The aim of the report is to give a summary documentation of the safety analysis input data and their scientific background. For secure containment of radioactive waste safety barriers are used which effectively limit the release of radioactive material from the repository (release barriers) and effectively retard the entry of the original radioactive material into the biosphere (time barriers). Safety barriers take the form of both technically constructed containment measures and the siting of the repository in suitable geological formations. The technical safety barrier system in the case of high-level waste comprises: the waste solidification matrix (borosilicate glass), massive steel canisters, encasement of the waste canisters, encasement of the waste canisters in highly compacted bentonite, sealing of vacant storage space and access routes on repository closure. The natural geological safety barriers - the host rock and overlying formations provide sufficiently long deep groundwater flow times from the repository location to the earth's surface and for additional lengthening of radionuclide migration times by means of various chemical and physical retardation mechanisms. The stability of the geological formations is so great that hydrogeological system is protected for a sufficient length of time from deterioration caused, in particular, by erosion. Observations in the final section of the report indicate that input data for the type C repository safety

  12. Electrical spin injection into high mobility 2D systems.

    Oltscher, M; Ciorga, M; Utz, M; Schuh, D; Bougeard, D; Weiss, D

    2014-12-05

    We report on spin injection into a high mobility 2D electron system confined at an (Al,Ga)As/GaAs interface, using (Ga,Mn)As Esaki diode contacts as spin aligners. We measured a clear nonlocal spin valve signal, which varies nonmonotonically with the applied bias voltage. The magnitude of the signal cannot be described by the standard spin drift-diffusion model, because at maximum this would require the spin polarization of the injected current to be much larger than 100%, which is unphysical. A strong correlation of the spin signal with contact width and electron mean free path suggests that ballistic transport in the 2D region below ferromagnetic contacts should be taken into account to fully describe the results.

  13. A third generation mobile high energy radiography system

    Fry, D.A.; Valdez, J.E.; Johnson, C.S.; Kimerly, H.J.; Vananne, J.R.

    1997-01-01

    A third generation mobile high energy radiographic capability has been completed and put into service by the Los Alamos National Laboratory. The system includes a 6 MeV linac x-ray generator, Co-60 gamma source, all-terrain transportation, on-board power, real-time radiography (RTR), a control center, and a complete darkroom capability. The latest version includes upgraded and enhanced portability, flexibility, all-terrain operation, all-weather operation, and ease of use features learned from experience with the first and second generation systems. All systems were required to have the following characteristics; all-terrain, all-weather operation, self-powered, USAF airlift compatible, reliable, simple to setup, easy to operate, and all components two-person portable. The systems have met these characteristics to differing degrees, as is discussed in the following section, with the latest system being the most capable

  14. Analysis of administrative barriers in the industry of the high-rise construction in Russian Federation

    Zaychenko, Irina; Borremans, Alexandra; Gutman, Svetlana

    2018-03-01

    The article describes the concept and types of administrative barriers encountered in various areas of the enterprise. The particularities of the Russian high-rise construction industry are described and a comparative analysis of administrative barriers in this sector is performed. The main stages and administrative procedures when the developers implement investment and construction projects in the field of high-rise construction are determined. The regulatory and legal framework for the implementation of investment and project activities in the high-rise construction industry has been studied and conclusions have been drawn on its low level of precision in the issue of the formation of competitive and efficient high-rise construction markets. The average number of administrative procedures for the implementation of the investment and construction project in the field of high-rise construction is determined. The factors preventing the reduction of administrative barriers in the high-rise construction industry are revealed.

  15. Study of surface leakage current of AlGaN/GaN high electron mobility transistors

    Chen, YongHe; Zhang, Kai; Cao, MengYi; Zhao, ShengLei; Zhang, JinCheng; Hao, Yue; Ma, XiaoHua

    2014-01-01

    Temperature-dependent surface current measurements were performed to analyze the mechanism of surface conductance of AlGaN/GaN channel high-electron-mobility transistors by utilizing process-optimized double gate structures. Different temperatures and electric field dependence have been found in surface current measurements. At low electric field, the mechanism of surface conductance is considered to be two-dimensional variable range hopping. At elevated electric field, the Frenkel–Poole trap assisted emission governs the main surface electrons transportation. The extracted energy barrier height of electrons emitting from trapped state near Fermi energy level into a threading dislocations-related continuum state is 0.38 eV. SiN passivation reduces the surface leakage current by two order of magnitude and nearly 4 orders of magnitude at low and high electric fields, respectively. SiN also suppresses the Frenkel–Poole conductance at high temperature by improving the surface states of AlGaN/GaN. A surface treatment process has been introduced to further suppress the surface leakage current at high temperature and high field, which results in a decrease in surface current of almost 3 orders of magnitude at 476 K

  16. Complexities of short-term mobility for sex work and migration among sex workers: violence and sexual risks, barriers to care, and enhanced social and economic opportunities.

    Goldenberg, Shira M; Chettiar, Jill; Nguyen, Paul; Dobrer, Sabina; Montaner, Julio; Shannon, Kate

    2014-08-01

    Despite research on the health and safety of mobile and migrant populations in the formal and informal sectors globally, limited information is available regarding the working conditions, health, and safety of sex workers who engage in short-term mobility and migration. The objective of this study was to longitudinally examine work environment, health, and safety experiences linked to short-term mobility/migration (i.e., worked or lived in another city, province, or country) among sex workers in Vancouver, Canada, over a 2.5-year study period (2010-2012). We examined longitudinal correlates of short-term mobility/migration (i.e., worked or lived in another city, province, or country over the 3-year follow-up period) among 646 street and off-street sex workers in a longitudinal community-based study (AESHA). Of 646 sex workers, 10.84 % (n = 70) worked or lived in another city, province, or country during the study. In a multivariate generalized estimating equations (GEE) model, short-term mobility/migration was independently correlated with older age (adjusted odds ratio (AOR) 0.95, 95 % confidence interval (CI) 0.92-0.98), soliciting clients in indoor (in-call) establishments (AOR 2.25, 95 % CI 1.27-3.96), intimate partner condom refusal (AOR 3.00, 1.02-8.84), and barriers to health care (AOR 1.77, 95 % CI 1.08-2.89). In a second multivariate GEE model, short-term mobility for sex work (i.e., worked in another city, province, or country) was correlated with client physical/sexual violence (AOR 1.92, 95 % CI 1.02-3.61). In this study, mobile/migrant sex workers were more likely to be younger, work in indoor sex work establishments, and earn higher income, suggesting that short-term mobility for sex work and migration increase social and economic opportunities. However, mobility and migration also correlated with reduced control over sexual negotiation with intimate partners and reduced health care access, and mobility for sex work was associated with

  17. A high rotational barrier for physisorbed hydrogen in an fcu-metal-organic framework

    Pham, Tony T.; Forrest, Katherine A.; Georgiev, Peter A L; Lohstroh, Wiebke; Xue, Dongxu; Hogan, Adam; Eddaoudi, Mohamed; Space, Brian; Eckert, Juergen

    2014-01-01

    A combined inelastic neutron scattering (INS) and theoretical study of H2 sorption in Y-FTZB, a recently reported metal-organic framework (MOF) with fcu topology, reveals that the strongest binding site in the MOF causes a high barrier to rotation on the sorbed H2. This rotational barrier for H2 is the highest yet of reported MOF materials based on physisorption. This journal is

  18. High rates of hybridisation reveal fragile reproductive barriers between endangered Australian sea snakes

    Sanders, Kate L; Redsted Rasmussen, Arne; Guinea, Michael L.

    2014-01-01

    designations, but revealed high frequencies of hybrids on all four reefs and individuals of pure A. fuscus ancestry only at Scott and (historically) Ashmore. Most unexpectedly, 95% of snakes sampled at Hibernia were hybrids that resembled A. laevis in phenotype, revealing a collapse of reproductive barriers...... (‘reverse speciation’) at this reef. These results have dire implications for the conservation status of A. fuscus, and highlight the fragility of reproductive barriers in a recent marine radiation....

  19. Data dissemination in the wild: A testbed for high-mobility MANETs

    Vingelmann, Peter; Pedersen, Morten Videbæk; Heide, Janus

    2012-01-01

    This paper investigates the problem of efficient data dissemination in Mobile Ad hoc NETworks (MANETs) with high mobility. A testbed is presented; which provides a high degree of mobility in experiments. The testbed consists of 10 autonomous robots with mobile phones mounted on them. The mobile...... information, and the goal is to convey that information to all devices. A strategy is proposed that uses UDP broadcast transmissions and random linear network coding to facilitate the efficient exchange of information in the network. An application is introduced that implements this strategy on Nokia phones...

  20. Exploring the mobility of cryoconite on High-Arctic glaciers

    Irvine-Fynn, T. D.; Hodson, A. J.; Bridge, J. W.; Langford, H.; Anesio, A.; Ohlanders, N.; Newton, S.

    2010-12-01

    There has been a growing awareness of the significance of biologically active dust (cryoconite) on the energy balance of, and nutrient cycling at glacier surfaces. Moreover, researchers have estimated the mass of biological material released from glacier ice to downstream environments and ecosystems, including the melt-out of cells from emergent ice in the ablation area. However, the processes, rates and mechanisms of cryoconite mobility and transport have not been fully explored. For many smaller valley glaciers in the High-Arctic, the climate dictates only a thin (~ 1m) layer of ice at the glacier surface is at the melting point during the summer months. This surface ice is commonly characterized by an increased porosity in response to incident energy and hydraulic conditions, and has been termed the “weathering crust”. The presence of cryoconite, with its higher radiation absorption, exacerbates the weathering crust development. Thus, crucially, the transport of cryoconite is not confined to simply a ‘smooth’ ice surface, but rather also includes mobility in the near-surface ice matrix. Here, we present initial results from investigations of cryoconite transport at Midtre Lovénbreen and Longyearbreen, two north-facing valley glaciers in Svalbard (Norway). Using time-lapse imagery, we explore the transport rates of cryoconite on a glacier surface and consider the associations between mobility and meteorological conditions. Results suggest some disparity between micro-, local- and plot-scale observations of cryoconite transport: the differences imply controlling influences of cryoconite volume, ice surface topography and ice structure. While to examine the relative volumes of cryoconite exported from the glacier surface by supraglacial streams we employ flow cytometry, using SYBR-Green-II staining to identify the biological component of the suspended load. Preliminary comparisons between shallow (1m) ice cores and in-stream concentrations suggest

  1. High Thermoelectric Power Factor of High-Mobility 2D Electron Gas.

    Ohta, Hiromichi; Kim, Sung Wng; Kaneki, Shota; Yamamoto, Atsushi; Hashizume, Tamotsu

    2018-01-01

    Thermoelectric conversion is an energy harvesting technology that directly converts waste heat from various sources into electricity by the Seebeck effect of thermoelectric materials with a large thermopower ( S ), high electrical conductivity (σ), and low thermal conductivity (κ). State-of-the-art nanostructuring techniques that significantly reduce κ have realized high-performance thermoelectric materials with a figure of merit ( ZT = S 2 ∙σ∙ T ∙κ -1 ) between 1.5 and 2. Although the power factor (PF = S 2 ∙σ) must also be enhanced to further improve ZT , the maximum PF remains near 1.5-4 mW m -1 K -2 due to the well-known trade-off relationship between S and σ. At a maximized PF, σ is much lower than the ideal value since impurity doping suppresses the carrier mobility. A metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) structure on an AlGaN/GaN heterostructure is prepared. Applying a gate electric field to the MOS-HEMT simultaneously modulates S and σ of the high-mobility electron gas from -490 µV K -1 and ≈10 -1 S cm -1 to -90 µV K -1 and ≈10 4 S cm -1 , while maintaining a high carrier mobility (≈1500 cm 2 V -1 s -1 ). The maximized PF of the high-mobility electron gas is ≈9 mW m -1 K -2 , which is a two- to sixfold increase compared to state-of-the-art practical thermoelectric materials.

  2. Barriers to health education in adolescents: health care providers' perspectives compared to high school adolescents.

    Abedian, Kobra; Shahhosseini, Zohreh

    2015-11-01

    Although adolescence is marked by profound and dynamic changes, it is virtually neglected by health care providers, by society, and even by most parents, teachers, and health professionals. The aim of this study was to investigate barriers to health education in adolescents from health care providers' views compared to teens. The study population consisted of 72 health care providers and 402 high school female students in Northern Iran in 2012. They completed a self-administered questionnaire about their views on barriers to adolescents' health education. It is revealed that the major barrier to adolescents' health education from a health care providers' perspective is "Lack of private room for adolescents' health education", while "Lack of adolescents' interest to content of educational programs" is a significantly greater barrier to health education among adolescents. The results suggest that for adolescent health education, specific strategies should be used in adolescent health promotion programs.

  3. Metalorganic chemical vapor deposition growth and thermal stability of the AlInN/GaN high electron mobility transistor structure

    Yu, Hongbo; Ozturk, Mustafa; Demirel, Pakize; Cakmak, Huseyin; Bolukbas, Basar; Caliskan, Deniz; Ozbay, Ekmel

    2011-01-01

    The Al x In 1−x N barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al 0.83 In 0.17 N barrier exhibits a sheet electron density of 2.0 × 10 13 cm −2 with a high electron mobility of 1540 cm 2 V −1 s −1 . An Al 0.83 In 0.17 N barrier HEMT device with 1 µm gate length provides a current density of 1.0 A mm −1 at V GS = 0 V and an extrinsic transconductance of 242 mS mm −1 , which are remarkably improved compared to that of a conventional Al 0.3 Ga 0.7 N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 °C have been applied to Al 0.83 In 0.17 N and Al 0.3 Ga 0.7 N barrier heterostructures. As expected, the electrical properties of an Al 0.83 In 0.17 N barrier HEMT structure showed less stability than that of an Al 0.3 Ga 0.7 N barrier HEMT to the thermal annealing. The structural properties of Al 0.83 In 0.17 N/GaN also showed more evidence for decomposition than that of the Al 0.3 Ga 0.7 N/GaN structure after 800 °C post-annealing

  4. Use of Mobile Clinical Decision Support Software by Junior Doctors at a UK Teaching Hospital: Identification and Evaluation of Barriers to Engagement.

    Patel, Rakesh; Green, William; Shahzad, Muhammad Waseem; Larkin, Chris

    2015-08-13

    Clinical decision support (CDS) tools improve clinical diagnostic decision making and patient safety. The availability of CDS to health care professionals has grown in line with the increased prevalence of apps and smart mobile devices. Despite these benefits, patients may have safety concerns about the use of mobile devices around medical equipment. This research explored the engagement of junior doctors (JDs) with CDS and the perceptions of patients about their use. There were three objectives for this research: (1) to measure the actual usage of CDS tools on mobile devices (mCDS) by JDs, (2) to explore the perceptions of JDs about the drivers and barriers to using mCDS, and (3) to explore the perceptions of patients about the use of mCDS. This study used a mixed-methods approach to study the engagement of JDs with CDS accessed through mobile devices. Usage data were collected on the number of interactions by JDs with mCDS. The perceived drivers and barriers for JDs to using CDS were then explored by interviews. Finally, these findings were contrasted with the perception of patients about the use of mCDS by JDs. Nine of the 16 JDs made a total of 142 recorded interactions with the mCDS over a 4-month period. Only 27 of the 114 interactions (24%) that could be categorized as on-shift or off-shift occurred on-shift. Eight individual, institutional, and cultural barriers to engagement emerged from interviews with the user group. In contrast to reported cautions and concerns about the impact of clinicians' use of mobile phone on patient health and safety, patients had positive perceptions about the use of mCDS. Patients reported positive perceptions toward mCDS. The usage of mCDS to support clinical decision making was considered to be positive as part of everyday clinical practice. The degree of engagement was found to be limited due to a number of individual, institutional, and cultural barriers. The majority of mCDS engagement occurred outside of the workplace

  5. Pressure Amplification Off High Impedance Barriers in DDT

    Heatwole, Eric Mann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Broilo, Robert M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kistle, Trevin Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Parker, Gary Robert Jr. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2018-04-23

    The Deflagration-to-Detonation Transition (DDT) in one-dimensional porous explosive, where combustion in an explosive transitions to detonation, can be described by the following model. This simplified model proceeds in five steps, as follows: 1) Ignition of the explosive, surface burning. 2) Convective burning, with the flame front penetrating through the porous network of the explosive. This proceeds until the pressure grows high enough to result in choked flow in the pores restricting the convective burn. 3) The choked flow results in the formation of a high-density compact of explosive. This compact is driven into undisturbed material by the pressure of the burning explosive. See Figure1. 4) The compression of the undisturbed porous explosive by the compact leads to the ignition of a compressive burn. This builds in pressure until a supported shock forms. 5) The shock builds in pressure until detonation occurs. See Figure 2 for an overview streak of the proceeding steps.

  6. Saudi high school students' attitudes and barriers toward the use of computer technologies in learning English.

    Sabti, Ahmed Abdulateef; Chaichan, Rasha Sami

    2014-01-01

    This study examines the attitudes of Saudi Arabian high school students toward the use of computer technologies in learning English. The study also discusses the possible barriers that affect and limit the actual usage of computers. Quantitative approach is applied in this research, which involved 30 Saudi Arabia students of a high school in Kuala Lumpur, Malaysia. The respondents comprised 15 males and 15 females with ages between 16 years and 18 years. Two instruments, namely, Scale of Attitude toward Computer Technologies (SACT) and Barriers affecting Students' Attitudes and Use (BSAU) were used to collect data. The Technology Acceptance Model (TAM) of Davis (1989) was utilized. The analysis of the study revealed gender differences in attitudes toward the use of computer technologies in learning English. Female students showed high and positive attitudes towards the use of computer technologies in learning English than males. Both male and female participants demonstrated high and positive perception of Usefulness and perceived Ease of Use of computer technologies in learning English. Three barriers that affected and limited the use of computer technologies in learning English were identified by the participants. These barriers are skill, equipment, and motivation. Among these barriers, skill had the highest effect, whereas motivation showed the least effect.

  7. Quantitative performance allocation of multi-barrier system for high-level radioactive waste disposal

    Ahn, Joon-Hong; Ikeda, Takao; Ohe, Toshiaki

    1995-01-01

    Performance assessment of each barrier consisting of geologic disposal system for high-level radioactive wastes is carried out quantitatively, and key radionuclides and parameters are pointed out. Chemical compositions and solubilities of radionuclides under repository conditions are determined by PHREEQE code staring from compositions of granitic groundwater observed in Japan. Glass dissolution analysis based on mass transfer theory and precipitation analysis have been done in order to determine the inner boundary condition for radionuclide diffusion through a bentonite-filled buffer region, where multi-member decay chain and isotopic sharing of solubility at the inner boundary are considered. Natural barrier is treated as homogeneous porous rock, or porous rock with infinite planar fractures. Performance of each barrier is evaluated in terms of non-dimensionalized hazard defined as the ratio of annual radioactivity release from each barrier to the annual limit on intake. At the outer edge of the engineered barriers, 239 Pu is the key unclide to the performance, whereas at the exit of the natural barrier, weakly-sorbing fission product nuclides such as 135 Cs, 129 I and 99 Tc dominate the hazard. (author) 50 refs

  8. BEYOND THE WORK-LIFE BALANCE: FAMILY AND INTERNATIONAL MOBILITY OF THE HIGHLY SKILLED

    Núria Vergés Bosch

    2013-10-01

    Full Text Available International mobility of the highly skilled has become one of the cornerstones of development in the current knowledge society. Correspondingly, highly skilled personnel are impelled to move abroad in order to improve their competences and build influential professional networks. Mobility implies some advantages involving personal, social and family opportunities when movers experience handicaps in their country of origin. For movers, mobility becomes a new challenge beyond the work-family balance, particularly for women who usually take on the lion’s share of childcare and domestic tasks within the family. The literature exploring the gender dimension in relation to international mobility points to complex outcomes. Firstly, women are taking on a more active role in international mobility processes, even when they have family. Secondly, family and international mobility are interrelated both for men and for women, although family could become a hindrance, particularly for women. Thirdly, international mobility and women’s career development may interfere with family formation or modify traditional family values. Finally, families moving abroad constitute a challenge for public policy, since they present a new area of problems. We aim to analyse the relationship between international mobility and family based on in-depth interviews from a purposive sample of highly skilled personnel in science and technology. The results of our research suggest that international mobility of the highly skilled has effects on the family and vice versa; however, while international mobility and family are compatible, measures and policies to reconcile them are still insufficient.

  9. Investigation of significantly high barrier height in Cu/GaN Schottky diode

    Manjari Garg

    2016-01-01

    Full Text Available Current-voltage (I-V measurements combined with analytical calculations have been used to explain mechanisms for forward-bias current flow in Copper (Cu Schottky diodes fabricated on Gallium Nitride (GaN epitaxial films. An ideality factor of 1.7 was found at room temperature (RT, which indicated deviation from thermionic emission (TE mechanism for current flow in the Schottky diode. Instead the current transport was better explained using the thermionic field-emission (TFE mechanism. A high barrier height of 1.19 eV was obtained at room temperature. X-ray photoelectron spectroscopy (XPS was used to investigate the plausible reason for observing Schottky barrier height (SBH that is significantly higher than as predicted by the Schottky-Mott model for Cu/GaN diodes. XPS measurements revealed the presence of an ultrathin cuprous oxide (Cu2O layer at the interface between Cu and GaN. With Cu2O acting as a degenerate p-type semiconductor with high work function of 5.36 eV, a high barrier height of 1.19 eV is obtained for the Cu/Cu2O/GaN Schottky diode. Moreover, the ideality factor and barrier height were found to be temperature dependent, implying spatial inhomogeneity of barrier height at the metal semiconductor interface.

  10. Dust mobilization by high-speed vapor flow under LOVA

    Matsuki, K.; Suzuki, S.; Ebara, S.; Yokomine, T.; Shimizu, A.

    2006-01-01

    In the safety analysis on the International Thermonuclear Experimental Reactor (ITER), the ingress of coolant (ICE) event and the loss of vacuum (LOVA) event are considered as one of the most serious accident. On the assumption of LOVA occurring after ICE, it is inferable that activated dusts are under the wet condition. Transport behavior of in-vessel activated dusts under the wet condition is not well understood in comparison with the dry case. In this study, we experimentally investigated the entrainment behavior of dust under LOVA after ICE. We measured dust entrainment by high-speed humid airflow with phase change. Graphite dusts and glass beads are used as substitutions for mobile inventory. The relations among the relative humidity, the entrainment of particles in the exhaust gas flow and the adhesion rate of dust particles on the pipe wall have been made clear, as has the distribution profile of dust deposition on the pipe wall. The entrainment ratio decreased as the relative humidity increased and increased as the initial pressure difference increased

  11. Application of CFRP with High Hydrogen Gas Barrier Characteristics to Fuel Tanks of Space Transportation System

    Yonemoto, Koichi; Yamamoto, Yuta; Okuyama, Keiichi; Ebina, Takeo

    In the future, carbon fiber reinforced plastics (CFRPs) with high hydrogen gas barrier performance will find wide applications in all industrial hydrogen tanks that aim at weight reduction; the use of such materials will be preferred to the use of conventional metallic materials such as stainless steel or aluminum. The hydrogen gas barrier performance of CFRP will become an important issue with the introduction of hydrogen-fuel aircraft. It will also play an important role in realizing fully reusable space transportation system that will have high specific tensile CFRP structures. Such materials are also required for the manufacture of high-pressure hydrogen gas vessels for use in the fuel cell systems of automobiles. This paper introduces a new composite concept that can be used to realize CFRPs with high hydrogen gas barrier performance for applications in the cryogenic tanks of fully reusable space transportation system by the incorporation of a nonmetallic crystal layer, which is actually a dense and highly oriented clay crystal laminate. The preliminary test results show that the hydrogen gas barrier characteristics of this material after cryogenic heat shocks and cyclic loads are still better than those of other polymer materials by approximately two orders of magnitude.

  12. High pH mobile phase effects on silica-based reversed-phase high-performance liquid chromatographic columns

    Kirkland, J.J.; Straten, van M.A.; Claessens, H.A.

    1995-01-01

    Aqueous mobile phases above pH 8 often cause premature column failure, limiting the utility of silica-based columns for applications requiring high pH. Previous studies suggest that covalently bound silane ligands are hydrolyzed and removed by high-pH mobile phases. However, we found that the

  13. Degradation of AlGaN/GaN High Electron Mobility Transistors with Different AlGaN Layer Thicknesses under Strong Electric Field

    Ling, Yang; Yue, Hao; Xiao-Hua, Ma; Jing-Jing, Ma; Cheng, Zhu

    2010-01-01

    The degradation of AlGaN/GaN high electron mobility transistors (HEMTs) has a close relationship with a model of traps in AlGaN barriers as a result of high electric field. We mainly discuss the impacts of strong electrical field on the AlGaN barrier thickness of AlGaN/GaN HEMTs. It is found that the device with a thin AlGaN barrier layer is more easily degraded. We study the degradation of four parameters, i.e. the gate series resistance R Gate , channel resistance R channel , gate current I G,off at V GS = −5 and V DS = 0.1 V, and drain current I D,max at V GS = 2 and V DS = 5 V. In addition, the degradation mechanisms of the device electrical parameters are also investigated in detail. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Scattering and mobility in indium gallium arsenide channel, pseudomorphic high electron mobility transistors (InGaAs pHEMTs)

    Pearson, J.L.

    1999-03-01

    Extensive transport measurements have been completed on deep and shallow-channelled InGaAs p-HEMTs of varying growth temperature, indium content, spacer thickness and doping density, with a view to a thorough characterisation, both in the metallic and the localised regimes. Particular emphasis was given to MBE grown layers, with characteristics applicable for device use, but low measurement temperatures were necessary to resolve the elastic scattering mechanisms. Measurements made in the metallic regime included transport and quantum mobility - the former over a range of temperatures between 1.5K to 300K. Conductivity measurements were also acquired in the strong localisation regime between about 1.5K and 100K. Experimentally determined parameters were tested for comparison with those predicted by an electrostatic model. Excellent agreement was obtained for carrier density. Other parameters were less well predicted, but the relevant experimental measurements, including linear depletion of the 2DEG, were sensitive to any excess doping above a 'critical' value determined by the model. At low temperature (1.5K), it was found that in all samples tested, transport mobility was strongly limited at all carrier densities by a large q mechanism, possibly intrinsic to the channel. This was ascribed either to scattering by the long-range potentials arising from the indium concentration fluctuations or fluctuations in the thickness of the channel layer. This mechanism dominates the transport at low carrier densities for all samples, but at high carrier density, an additional mechanism is significant for samples with the thinnest spacers tested (2.5nm). This is ascribed to direct electron interaction with the states of the donor layer, and produces a characteristic transport mobility peak. At higher carrier densities, past the peak, quantum mobility was found only to increase monotonically in value. Remote ionised impurity scattering while significant, particularly for samples

  15. A compact high resolution electrospray ionization ion mobility spectrometer.

    Reinecke, T; Kirk, A T; Ahrens, A; Raddatz, C-R; Thoben, C; Zimmermann, S

    2016-04-01

    Electrospray is a commonly used ionization method for the analysis of liquids. An electrospray is a dispersed nebular of charged droplets produced under the influence of a strong electrical field. Subsequently, ions are produced in a complex process initiated by evaporation of neutral solvent molecules from these droplets. We coupled an electrospray ionization source to our previously described high resolution ion mobility spectrometer with 75 mm drift tube length and a drift voltage of 5 kV. When using a tritium source for chemical gas phase ionization, a resolving power of R=100 was reported for this setup. We replaced the tritium source and the field switching shutter by an electrospray needle, a desolvation region with variable length and a three-grid shutter for injecting ions into the drift region. Preliminary measurements with tetraalkylammonium halides show that the current configuration with the electrospray ionization source maintains the resolving power of R=100. In this work, we present the characterization of our setup. One major advantage of our setup is that the desolvation region can be heated separately from the drift region so that the temperature in the drift region stays at room temperature even up to desolvation region temperatures of 100 °C. We perform parametric studies for the investigation of the influence of temperature on solvent evaporation with different ratios of water and methanol in the solvent for different analyte substances. Furthermore, the setup is operated in negative mode and spectra of bentazon with different solvents are presented. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Grady, R; Bayram, C

    2017-01-01

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

  17. Development of high performance Schottky barrier diode and its application to plasma diagnostics

    Fujita, Junji; Kawahata, Kazuo; Okajima, Shigeki

    1993-10-01

    At the conclusion of the Supporting Collaboration Research on 'Development of High Performance Detectors in the Far Infrared Range' carried out from FY1990 to FY1992, the results of developing Schottky barrier diode and its application to plasma diagnostics are summarized. Some remarks as well as technical know-how for the correct use of diodes are also described. (author)

  18. Ugandan Immigrant Students' Perceptions of Barriers to Academic Achievement in American High Schools

    Ssekannyo, Denis

    2010-01-01

    In a world that is now a global village, enterprising individuals, especially from Third World countries, who make it to greener pastures do not leave their children behind. But with a long list of barriers to academic achievement associated with immigrant and minority students in American high schools, an understanding of the experiences and…

  19. High-Risk Smoking Behaviors and Barriers to Smoking Cessation Among Homeless Individuals.

    Chen, Joseph S; Nguyen, Austin Huy; Malesker, Mark A; Morrow, Lee E

    2016-05-01

    Although tobacco practices and the effects of tobacco use among the general American population are well described, minimal data exist regarding tobacco use and barriers to smoking cessation among homeless individuals. Anonymous, voluntary surveys based on a previously implemented instrument were completed by 100 smoking individuals residing at a homeless shelter. These surveys assessed high-risk smoking behaviors and respondents' perceived barriers to long-term smoking cessation. Ninety percent of study participants reported engaging in at least one of the high-risk tobacco practices. Nicotine replacement therapy was perceived by respondents to be the most desired form of smoking cessation aid. Excessive stress with use of tobacco smoking to alleviate stress and anxiety was the most significant self-perceived barrier to smoking cessation. High-risk tobacco practices are remarkably common among smoking homeless individuals. Despite literature consistently showing that non-nicotine tobacco cessation pharmacotherapies (varenicline, buproprion) have higher smoking cessation rates, nicotine replacement monotherapy was perceived as more valuable by survey respondents. Although lack of financial resources was expected to be the biggest barrier to successful cessation, social stressors and the use of smoking to cope with homelessness were perceived as a greater obstacle in this cohort. Given the paucity of data on the long-term effects of the high-risk tobacco behaviors reported by these homeless smokers, this study highlights the need for further investigations regarding tobacco use and tobacco cessation in this vulnerable population. Copyright © 2016 by Daedalus Enterprises.

  20. High Speed Mobility Through On-Demand Aviation

    Moore, Mark D.; Goodrich, Ken; Viken, Jeff; Smith, Jeremy; Fredericks, Bill; Trani, Toni; Barraclough, Jonathan; German, Brian; Patterson, Michael

    2013-01-01

    automobiles. ?? Community Noise: Hub and smaller GA airports are facing increasing noise restrictions, and while commercial airliners have dramatically decreased their community noise footprint over the past 30 years, GA aircraft noise has essentially remained same, and moreover, is located in closer proximity to neighborhoods and businesses. ?? Operating Costs: GA operating costs have risen dramatically due to average fuel costs of over $6 per gallon, which has constrained the market over the past decade and resulted in more than 50% lower sales and 35% less yearly operations. Infusion of autonomy and electric propulsion technologies can accomplish not only a transformation of the GA market, but also provide a technology enablement bridge for both larger aircraft and the emerging civil Unmanned Aerial Systems (UAS) markets. The NASA Advanced General Aviation Transport Experiments (AGATE) project successfully used a similar approach to enable the introduction of primary composite structures and flat panel displays in the 1990s, establishing both the technology and certification standardization to permit quick adoption through partnerships with industry, academia, and the Federal Aviation Administration (FAA). Regional and airliner markets are experiencing constant pressure to achieve decreasing levels of community emissions and noise, while lowering operating costs and improving safety. But to what degree can these new technology frontiers impact aircraft safety, the environment, operations, cost, and performance? Are the benefits transformational enough to fundamentally alter aircraft competiveness and productivity to permit much greater aviation use for high speed and On-Demand Mobility (ODM)? These questions were asked in a Zip aviation system study named after the Zip Car, an emerging car-sharing business model. Zip Aviation investigates the potential to enable new emergent markets for aviation that offer "more flexibility than the existing transportation solutions

  1. Anti-high mobility group box-1 antibody therapy for traumatic brain injury.

    Okuma, Yu; Liu, Keyue; Wake, Hidenori; Zhang, Jiyong; Maruo, Tomoko; Date, Isao; Yoshino, Tadashi; Ohtsuka, Aiji; Otani, Naoki; Tomura, Satoshi; Shima, Katsuji; Yamamoto, Yasuhiko; Yamamoto, Hiroshi; Takahashi, Hideo K; Mori, Shuji; Nishibori, Masahiro

    2012-09-01

    High mobility group box-1 (HMGB1) plays an important role in triggering inflammatory responses in many types of diseases. In this study, we examined the involvement of HMGB1 in traumatic brain injury (TBI) and evaluated the ability of intravenously administered neutralizing anti-HMGB1 monoclonal antibody (mAb) to attenuate brain injury. Traumatic brain injury was induced in rats or mice by fluid percussion. Anti-HMGB1 mAb or control mAb was administered intravenously after TBI. Anti-HMGB1 mAb remarkably inhibited fluid percussion-induced brain edema in rats, as detected by T2-weighted magnetic resonance imaging; this was associated with inhibition of HMGB1 translocation, protection of blood-brain barrier (BBB) integrity, suppression of inflammatory molecule expression, and improvement of motor function. In contrast, intravenous injection of recombinant HMGB1 dose-dependently produced the opposite effects. Experiments using receptor for advanced glycation end product (RAGE)(-/-) , toll-like receptor-4 (TLR4)(-/-) , and TLR2(-/-) mice suggested the involvement of RAGE as the predominant receptor for HMGB1. Anti-HMGB1 mAb may provide a novel and effective therapy for TBI by protecting against BBB disruption and reducing the inflammatory responses induced by HMGB1. Copyright © 2012 American Neurological Association.

  2. Photochemical approach to high-barrier films for the encapsulation of flexible laminary electronic devices

    Prager, L., E-mail: lutz.prager@iom-leipzig.de [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Helmstedt, U. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Herrnberger, H. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Kahle, O. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany); Kita, F. [AZ Electronic Materials Germany GmbH, Rheingaustraße 190-196, 65203 Wiesbaden (Germany); Münch, M. [Solarion AG, Pereser Höhe 1, Breitscheidstraße 45, 04442 Zwenkau (Germany); Pender, A.; Prager, A.; Gerlach, J.W. [Leibniz-Institut für Oberflächenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Stasiak, M. [Fraunhofer-Einrichtung für Polymermaterialien und Composite PYCO, Kantstraße 55, 14513 Teltow (Germany)

    2014-11-03

    Based on results of preceding research and development, thin gas barriers were made by wet application of perhydropolysilazane solution onto polymer films and its subsequent photo-initiated conversion to dense silica layers applying vacuum ultraviolet irradiation. Compared to the state of the art, these layers were sufficiently improved and characterized by spectroscopic methods, by scanning electron microscopy and by gas permeation measurements. Water vapor transmission rates (WVTR) below 10{sup −2} g m{sup −2} d{sup −1} were achieved. In this way, single barrier films were developed and produced on a pilot plant from roll to roll, 250 mm wide, at speeds up to 10 m min{sup −1}. Two films were laminated using adhesives curable with ultraviolet (UV) light and evaluated by peel tests, gas permeation measurement and climate testing. It could be shown that the described high-barrier laminates which exhibit WVTR ≈ 5 × 10{sup −4} g m{sup −2} d{sup −1}, determined by the calcium mirror method, are suitable for encapsulation of flexible thin-film photovoltaic modules. Durability of the encapsulated modules could be verified in several climate tests including damp-heat, thermo-cycle (heating, freezing, wetting) and UV exposures which are equivalent to more than 20 years of endurance at outdoor conditions in temperate climate. In the frame of further research and technical development it seems to be possible to design a cost efficient industrial scale process for the production of encapsulation films for photovoltaic applications. - Highlights: • Dense silica barrier layers were developed by a photochemical approach. • Polymer based barrier films were laminated yielding flexible high-barrier films. • Using these laminates photovoltaic test modules were encapsulated and tested. • A durability of more than 20 years at outdoor conditions could be proved.

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

    Hou, Zhipeng; Wang, Wenhong; Xu, Guizhou; Zhang, Xiaoming; Wei, Zhiyang; Shen, Shipeng; Liu, Enke; Yao, Yuan; Chai, Yisheng; Sun, Young; Xi, Xuekui; Wang, Wenquan; Liu, Zhongyuan; Wu, Guangheng; Zhang, Xixiang

    2015-01-01

    Materials with high carrier mobility showing large magnetoresistance (MR) have recently received much attention because of potential applications in future high-performance magnetoelectric devices. Here, we report on an electron-hole

  4. Nurses Need Training and Policies to Address Barriers to Use of Mobile Devices and Apps for Direct Patient Care in Hospital Settings

    Kelley Wadson

    2018-03-01

    were then given a two-month period to use the apps for patient care. Afterward, they completed the same survey from Phase I and their pre- and post-intervention responses were matched for comparative analysis. Phase II concluded with a one-hour audio-recorded focus group using ten open-ended questions to gather feedback on the impact of the educational sessions. Main Results – 94 nurses completed the Phase I survey for a response rate of 27%. Although 89 respondents reported owning a mobile device, less than half used them for patient care. Just under half the respondents were unsure if they were allowed to use mobile devices at work and a similar number answered that devices were not allowed. Two-thirds of respondents were unsure whether any institutional policies existed regarding mobile device use. Of the 16 participants that volunteered for Phase II, 14 completed the post-intervention survey and 6 attended the focus group. In comparison to the Phase I survey, post-intervention survey responses showed more awareness of institutional policies and increased concern about mobile devices causing distraction. In the Phase I survey, just over half of the nurses expressed a desire to use mobile devices in patient care. Four themes emerged from the survey’s qualitative responses in Phase I: (1 policy: nurses were unsure of institutional policy or experienced either disapproval or bans on mobile device use from management; (2 barriers to use, namely cost, potential damage to or loss of devices, infection control, and lack of familiarity with technology; (3 patient perceptions, including generational differences with younger patients seen as more accepting than older patients; and (4 nurse perceptions: most valued access to information but expressed concerns about distraction, undermining of professionalism, and use of technology. Qualitative responses in the Phase II survey and focus group also revealed four themes: (1 barriers: participants did not cite loss of device

  5. Imbalance of gut microbiome and intestinal epithelial barrier dysfunction in patients with high blood pressure.

    Kim, Seungbum; Goel, Ruby; Kumar, Ashok; Qi, Yanfei; Lobaton, Gil; Hosaka, Koji; Mohammed, Mohammed; Handberg, Eileen M; Richards, Elaine M; Pepine, Carl J; Raizada, Mohan K

    2018-03-30

    Recent evidence indicates a link between gut pathology and microbiome with hypertension (HTN) in animal models. However, whether this association exists in humans is unknown. Thus, our objectives in the present study were to test the hypotheses that high blood pressure (BP) patients have distinct gut microbiomes and that gut-epithelial barrier function markers and microbiome composition could predict systolic BP (SBP). Fecal samples, analyzed by shotgun metagenomics, displayed taxonomic and functional changes, including altered butyrate production between patients with high BP and reference subjects. Significant increases in plasma of intestinal fatty acid binding protein (I-FABP), lipopolysaccharide (LPS), and augmented gut-targetting proinflammatory T helper 17 (Th17) cells in high BP patients demonstrated increased intestinal inflammation and permeability. Zonulin, a gut epithelial tight junction protein regulator, was markedly elevated, further supporting gut barrier dysfunction in high BP. Zonulin strongly correlated with SBP (R 2 = 0.5301, P <0.0001). Two models predicting SBP were built using stepwise linear regression analysis of microbiome data and circulating markers of gut health, and validated in a separate cohort by prediction of SBP from zonulin in plasma (R 2 = 0.4608, P <0.0001). The mouse model of HTN, chronic angiotensin II (Ang II) infusion, was used to confirm the effects of butyrate and gut barrier function on the cardiovascular system and BP. These results support our conclusion that intestinal barrier dysfunction and microbiome function are linked to HTN in humans. They suggest that manipulation of gut microbiome and its barrier functions could be the new therapeutic and diagnostic avenues for HTN. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  6. Hold the Phone! High School Students' Perceptions of Mobile Phone Integration in the Classroom

    Thomas, Kevin; Muñoz, Marco A.

    2016-01-01

    This study examined the survey responses of 628 high school students in a large urban school district to determine their perceptions of mobile phone use in the classroom. Findings indicated that the majority of students (90.7%) were using a variety of mobile phone features for school-related work. Student support for instructional uses of phones,…

  7. Mobilities of slow electrons in low- and high-pressure gases and liquids

    Christophorou, L.G.

    1975-01-01

    Mobilities of slow (thermal and epithermal) electrons in low- (less than or approximately 500 Torr) and high- (approximately 500 to approximately 34,111 Torr) pressure gases are discussed and are related to the molecular structure and to the mobilities of thermal electrons in liquid media

  8. The design of a linear L-band high power amplifier for mobile communication satellites

    Whittaker, N.; Brassard, G.; Li, E.; Goux, P.

    1990-01-01

    A linear L-band solid state high power amplifier designed for the space segment of the Mobile Satellite (MSAT) mobile communication system is described. The amplifier is capable of producing 35 watts of RF power with multitone signal at an efficiency of 25 percent and with intermodulation products better than 16 dB below carrier.

  9. Hall mobility of free charge carriers in highly compensated p-Germanium

    Gavrilyuk, V.Yi.; Kirnas, Yi.G.; Balakyin, V.D.

    2000-01-01

    Hall mobility of free charge carriers in initial detectors Ge (Ga) is studied. It is established that an increase in the compensation factor results in the enlargement of Hall mobility in germanium highly compensated by introduction of Li ions during their drift in an electrical field

  10. Direct Growth of High Mobility and Low-Noise Lateral MoS2 -Graphene Heterostructure Electronics.

    Behranginia, Amirhossein; Yasaei, Poya; Majee, Arnab K; Sangwan, Vinod K; Long, Fei; Foss, Cameron J; Foroozan, Tara; Fuladi, Shadi; Hantehzadeh, Mohammad Reza; Shahbazian-Yassar, Reza; Hersam, Mark C; Aksamija, Zlatan; Salehi-Khojin, Amin

    2017-08-01

    Reliable fabrication of lateral interfaces between conducting and semiconducting 2D materials is considered a major technological advancement for the next generation of highly packed all-2D electronic circuitry. This study employs seed-free consecutive chemical vapor deposition processes to synthesize high-quality lateral MoS 2 -graphene heterostructures and comprehensively investigated their electronic properties through a combination of various experimental techniques and theoretical modeling. These results show that the MoS 2 -graphene devices exhibit an order of magnitude higher mobility and lower noise metrics compared to conventional MoS 2 -metal devices as a result of energy band rearrangement and smaller Schottky barrier height at the contacts. These findings suggest that MoS 2 -graphene in-plane heterostructures are promising materials for the scale-up of all-2D circuitry with superlative electrical performance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. High-Speed Mobile Communications in Hostile Environments

    AUTHOR|(SzGeCERN)739920; Sierra, Rodrigo; Chapron, Frederic; CERN. Geneva. IT Department

    2015-01-01

    With the inexorable increase in the use of mobile devices, wireless connectivity is expected by users anywhere, anytime. In general, this requirement is addressed in office buildings or public locations through the use of Wi-Fi technology but Wi-Fi is not well adapted for use in large experiment halls and complex underground environments, especially those where radiation exposure is an issue, such as the LHC tunnel and experimental caverns. 4G/LTE technology, however, looks to be well adapted to addressing mobility needs in such areas. We report here the studies CERN has undertaken on the use of 4G/LTE in the LHC tunnel, presenting results on the data throughput that can be achieved and discussing issues such as the provision of a consistent user experience.

  12. High available and fault tolerant mobile communications infrastructure

    Beiroumi, Mohammad Zib

    2006-01-01

    using rollback or replication techniques inapplicable. This dissertation presents a novel failure recovery approach based on a behavioral model of the communication protocols. The new recovery method is able to deal with software and hardware faults and is particularly suitable for mobile communications...... as it is the case for many recovery techniques. In addition, the method does not require any modification to mobile clients. The Communicating Extended Finite State Machine (CEFSM) is used to model the behavior of the infrastructure applications. The model based recovery scheme is integrated in the application...... and uses the client/server model to save the application state information during failure-free execution on a stable storage and retrieve them when needed during recovery. When and what information to be saved/retrieved is determined by the behavioral model of the application. To practically evaluate...

  13. Hierarchical micro-mobility management in high-speed multihop access networks

    TANG Bi-hua; MA Xiao-lei; LIU Yuan-an; GAO Jin-chun

    2006-01-01

    This article integrates the hierarchical micro-mobility management and the high-speed multihop access networks (HMAN), to accomplish the smooth handover between different access routers. The proposed soft handover scheme in the high-speed HMAN can solve the micro-mobility management problem in the access network. This article also proposes the hybrid access router (AR) advertisement scheme and AR selection algorithm, which uses the time delay and stable route to the AR as the gateway selection parameters. By simulation, the proposed micro-mobility management scheme can achieve high packet delivery fraction and improve the lifetime of network.

  14. Measurement of leakage and design for the protective barrier of the high energy radiation therapy room

    Chu, S.S.; Park, C.Y.

    1981-01-01

    The logical development of an optimum structural shielding design and the computation of protective barriers for high energy radiation therapy room, Toshiba 13 MeV are presented. We obtained following results by comparison in between the precalculating values and actual survey after complete installation of radiogenerating units. 1) The calculating formula for the protective barrier written in NCRP report no. 34(1970) was the most ideal and economic calculating methods for the construction of barrier and to determine thickness for the meeting requirements of the number of patients of 80-100 in daily treatment. 2) The precalculating values of protective barrier are 5 times more protective than that of actual measurement. It is depending on radiation workload and utilization the data most securely. 3) The dose rate during exposure are 2-10 mR/hr at out of the door and the control room. 4) The foul smelling and ozone gas production from long exposure of cancer patients cannot be estimated when the room is ill ventilated. (author)

  15. Deep disposal of high activity radioactive wastes: the study of engineered and geological barriers behaviour

    Yu Jun; Cui; Delage, P.; Laure, E. de; Behrouz, Gatmiri; Sulem, J.; Anh Minh, Tang

    2008-09-01

    One option for the isolation of high activity and long lived radioactive wastes is the disposal of the vitrified waste containers in galleries dug inside impermeable rocks of the deep underground (granite, argillite, salt). The multi-barrier isolation concept is based on the use of successive barriers to avoid the migration of radionuclides towards the biosphere (container envelope, engineered barrier made of compacted swelling clay, and host rock). In parallel to the works carried out in underground laboratories, experiments and simulation works are performed in order to understand the behaviour of storage facilities and barriers under the effects of constraints, water fluxes and temperature changes. In this context, the UR Navier geotechnical team (CERMES), a joint research unit of Ecole des Ponts ParisTech and LCPC, has been working for more than 15 years on this topic for various contractors. These works are based on original experimental devices allowing to identify the thermo-hydro-mechanical phenomena and thereafter to model them. This dossier presents a summary of these works. (J.S.)

  16. Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

    Mohammed, H. A.; Sibley, M. J. N.; Mather, P. J.

    2012-05-01

    The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-input multiple-output (MIMO) is a promising mobile air interface solution for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. This paper details the design of a highly robust and efficient OFDM-MIMO system to support permanent accessibility and higher data rates to users moving at high speeds, such as users travelling on trains. It has high relevance for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The paper begins with a comprehensive literature review focused on both technologies. This is followed by the modelling of the OFDM-MIMO physical layer based on Simulink/Matlab that takes into consideration high vehicular mobility. Then the entire system is simulated and analysed under different encoding and channel estimation algorithms. The use of High Altitude Platform system (HAPs) technology is considered and analysed.

  17. Investigation of Doppler Effects on high mobility OFDM-MIMO systems with the support of High Altitude Platforms (HAPs)

    Mohammed, H A; Sibley, M J N; Mather, P J

    2012-01-01

    The merging of Orthogonal Frequency Division Multiplexing (OFDM) with Multiple-input multiple-output (MIMO) is a promising mobile air interface solution for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. This paper details the design of a highly robust and efficient OFDM-MIMO system to support permanent accessibility and higher data rates to users moving at high speeds, such as users travelling on trains. It has high relevance for next generation wireless local area networks (WLANs) and 4G mobile cellular wireless systems. The paper begins with a comprehensive literature review focused on both technologies. This is followed by the modelling of the OFDM-MIMO physical layer based on Simulink/Matlab that takes into consideration high vehicular mobility. Then the entire system is simulated and analysed under different encoding and channel estimation algorithms. The use of High Altitude Platform system (HAPs) technology is considered and analysed.

  18. Role of structural barriers for carotenoid bioaccessibility upon high pressure homogenization.

    Palmero, Paola; Panozzo, Agnese; Colle, Ines; Chigwedere, Claire; Hendrickx, Marc; Van Loey, Ann

    2016-05-15

    A specific approach to investigate the effect of high pressure homogenization on the carotenoid bioaccessibility in tomato-based products was developed. Six different tomato-based model systems were reconstituted in order to target the specific role of the natural structural barriers (chromoplast substructure/cell wall) and of the phases (soluble/insoluble) in determining the carotenoid bioaccessibility and viscosity changes upon high pressure homogenization. Results indicated that in the absence of natural structural barriers (carotenoid enriched oil), the soluble and insoluble phases determined the carotenoid bioaccessibility upon processing whereas, in their presence, these barriers governed the bioaccessibility. Furthermore, it was shown that the increment of the viscosity upon high pressure homogenization is determined by the presence of insoluble phase, however, this result was related to the initial ratio of the soluble:insoluble phases in the system. In addition, no relationship between the changes in viscosity and carotenoid bioaccessibility upon high pressure homogenization was found. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Ultra high hole mobilities in a pure strained Ge quantum well

    Mironov, O.A.; Hassan, A.H.A.; Morris, R.J.H.; Dobbie, A.; Uhlarz, M.; Chrastina, D.; Hague, J.P.; Kiatgamolchai, S.; Beanland, R.; Gabani, S.; Berkutov, I.B.; Helm, M.; Drachenko, O.; Myronov, M.; Leadley, D.R.

    2014-01-01

    Hole mobilities at low and room temperature (RT) have been studied for a strained sGe/SiGe heterostructure using standard Van der Pauw resistivity and Hall effect measurements. The range of magnetic field and temperatures used were − 14 T < B < + 14 T and 1.5 K < T < 300 K respectively. Using maximum entropy-mobility spectrum analysis (ME-MSA) and Bryan's algorithm mobility spectrum (BAMS) analysis, a RT two dimensional hole gas drift mobility of (3.9 ± 0.4) × 10 3 cm 2 /V s was determined for a sheet density (p s ) 9.8 × 10 10 cm −2 (by ME-MSA) and (3.9 ± 0.2) × 10 3 cm 2 /V s for a sheet density (p s ) 5.9 × 10 10 cm −2 (by BAMS). - Highlights: • Pure strained Ge channel grown by reduced pressure chemical vapor deposition • Maximum entropy-mobility spectrum analysis • Bryan's algorithm mobility spectrum analysis • High room temperature hole drift mobility of (3.9 ± 0.4) × 10 3 cm 2 /V s • Extremely high hole mobility of 1.1 × 10 6 cm 2 /V s at 12 K

  20. Overcoming barriers to high performance seismic design using lessons learned from the green building industry

    Glezil, Dorothy

    NEHRP's Provisions today currently governing conventional seismic resistant design. These provisions, though they ensure the life-safety of building occupants, extensive damage and economic losses may still occur in the structures. This minimum performance can be enhanced using the Performance-Based Earthquake Engineering methodology and passive control systems like base isolation and energy dissipation systems. Even though these technologies and the PBEE methodology are effective reducing economic losses and fatalities during earthquakes, getting them implemented into seismic resistant design has been challenging. One of the many barriers to their implementation has been their upfront costs. The green building community has faced some of the same challenges that the high performance seismic design community currently faces. The goal of this thesis is to draw on the success of the green building industry to provide recommendations that may be used overcome the barriers that high performance seismic design (HPSD) is currently facing.

  1. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    Medřický, J.; Curry, N.; Pala, Zdeněk; Vilémová, Monika; Chráska, Tomáš; Johansson, J.; Markocsan, N.

    2015-01-01

    Roč. 24, č. 4 (2015), s. 622-628 ISSN 1059-9630 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : gas turbine s * high temperature application * porosity of coatings * stabilized zirconia * thermal barrier coatings (TBCs) Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.568, year: 2015

  2. Investigation of Ozone Yield of Air Fed Ozonizer by High Pressure Homogeneous Dielectric Barrier Discharge

    2013-07-01

    around 2 ms and 12 ms in this figure, and during the discharge period, the current was continuous without any pulse . Once a discharge generated in...electron avalanches [10]. Fig. 1. High pressure ozone generator. (a) Top view (b) Side view Fig. 2. Barrier discharge device. Table 1... discharge N. Osawa P1 P, UY. Yoshioka UP2 P, R. Hanaoka P1 P 1 Center for Electric, Optic and Energy applications, Department of Electric and

  3. Physical activity in patients with type 2 diabetes and hypertension--insights into motivations and barriers from the MOBILE study.

    Duclos, Martine; Dejager, Sylvie; Postel-Vinay, Nicolas; di Nicola, Sylvie; Quéré, Stéphane; Fiquet, Béatrice

    2015-01-01

    Although physical activity (PA) is key in the management of type 2 diabetes (T2DM) and hypertension, it is difficult to implement in practice. Cross-sectional, observational study. Participating physicians were asked to recruit two active and four inactive patients, screened with the Ricci-Gagnon (RG) self-questionnaire (active if score ≥16). Patients subsequently completed the International Physical Activity Questionnaire. The objective was to assess the achievement of individualized glycated hemoglobin and blood pressure goals (active vs inactive cohort, to explore the correlates for meeting both targets by multivariate analysis, and to examine the barriers and motivations to engage in PA. About 1,766 patients were analyzed. Active (n=628) vs. inactive (n=1,138) patients were more often male, younger, less obese, had shorter durations of diabetes, fewer complications and other health issues, such as osteoarticular disorders (Pactive vs inactive patients was the percentage who declared engaging in regular leisure-type PA (97.9% vs. 9.6%), also reflected in the percentage with vigorous activities in International Physical Activity Questionnaire (59.5% vs. 9.6%). Target control was achieved by 33% of active and 19% of inactive patients (PActive patients, those with fewer barriers to PA, with lower treatment burden, and with an active physician, were more likely to reach targets. The physician's role emerged in the motivations (reassurance on health issues, training on hypoglycemia risk, and prescription/monitoring of the PA by the physician). A negative self-image was the highest ranked barrier for the inactive patients, followed by lack of support and medical concerns. Physicians should consider PA prescription as seriously as any drug prescription, and take into account motivations and barriers to PA to tailor advice to patients' specific needs and reduce their perceived constraints.

  4. The 2007 click it or ticket high-visibility seat belt mobilization : traffic tech.

    2010-09-01

    In May 2007 the National Highway Traffic Safety Administration : sponsored the fifth national Click It or Ticket (CIOT) : high-visibility seat belt enforcement mobilization, which followed : the CIOT program model of earned and paid media : publicizi...

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

    Holmes, Kenneth

    2002-01-01

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

  6. Diketopyrrolopyrrole-diketopyrrolopyrrole-based conjugated copolymer for high-mobility organic field-effect transistors

    Kanimozhi, Catherine K.; Yaacobi-Gross, Nir; Chou, Kang Wei; Amassian, Aram; Anthopoulos, Thomas D.; Patil, Satish P.

    2012-01-01

    In this communication, we report the synthesis of a novel diketopyrrolopyrrole-diketopyrrolopyrrole (DPP-DPP)-based conjugated copolymer and its application in high-mobility organic field-effect transistors. Copolymerization of DPP with DPP yields a

  7. Analytical modeling of trilayer graphene nanoribbon Schottky-barrier FET for high-speed switching applications.

    Rahmani, Meisam; Ahmadi, Mohammad Taghi; Abadi, Hediyeh Karimi Feiz; Saeidmanesh, Mehdi; Akbari, Elnaz; Ismail, Razali

    2013-01-30

    Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current-voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current-voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.

  8. Barriers to Pelvic Floor Physical Therapy Regarding Treatment of High-Tone Pelvic Floor Dysfunction.

    Zoorob, Dani; Higgins, Margaret; Swan, Kimberly; Cummings, Jennifer; Dominguez, Sarah; Carey, Erin

    Chronic pelvic pain is a prevalent and debilitating condition with a wide range of etiologies. An estimated 30% to 70% of chronic pelvic cases involve musculoskeletal component pain including high-tone pelvic floor dysfunction (HTPFD). Pelvic floor physical therapy has been shown to be a beneficial treatment for HTPFD, yet many patients do not have access to this treatment. The objective of this study was to identify the barriers preventing patients from following through with the first-line management, physical therapy. Participants with a diagnosis of HTPFD (n = 154) were identified from the list of referrals sent from the obstetrics and gynecology department to an affiliated PFPT center. Participants were contacted and asked to complete a phone survey addressing demographics and perceived barriers to care. Responses were collected in REDCap. Univariate and bivariate analyses were performed using a statistical analysis software. Seventy surveys were completed. The top barriers identified by participants were financial constraints (51.4%), perceived lack of utility (37.1%), time constraints (30.0%), and travel issues (18.6%); 84.4% of participants had 1 or more comorbid pain condition. Whereas 51.4% expressed some level of anxiety regarding the PFPT option, only 9.6% of participants did not start treatment because of fear of treatment. The majority of treatment barriers identified were concrete restraints, with insurance noncoverage and time constraints being the top issues. A fair number of participants expressed anxiety about the treatment or felt they received unclear explanations of the treatment. These are areas in which providers can potentially alleviate some barriers to care.

  9. High Precision GNSS Guidance for Field Mobile Robots

    Ladislav Jurišica

    2012-11-01

    Full Text Available In this paper, we discuss GNSS (Global Navigation Satellite System guidance for field mobile robots. Several GNSS systems and receivers, as well as multiple measurement methods and principles of GNSS systems are examined. We focus mainly on sources of errors and investigate diverse approaches for precise measuring and effective use of GNSS systems for real-time robot localization. The main body of the article compares two GNSS receivers and their measurement methods. We design, implement and evaluate several mathematical methods for precise robot localization.

  10. Powerful highly efficient KrF lamps excited by surface and barrier discharges

    Borisov, V M; Vodchits, V A; El'tsov, A V; Khristoforov, O B

    1998-01-01

    An investigation was made of the characteristics of KrF lamps with different types of excitation by surface and barrier discharges in which the dielectric material was sapphire. The conditions were determined for the attainment of an extremely high yield of the KrF* fluorescence with the internal efficiency η in ∼30 % and 22% for pulsed surface and barrier discharges, respectively. A homogeneous surface discharge was maintained without gas circulation when the pulse repetition rate was 5 x 10 4 Hz. Quasicontinuous excitation of a surface discharge at near-atmospheric pressure made it possible to reach a KrF* fluorescence power density of about 80 W cm -3 , which was close to the limit set by the kinetics of the gaseous medium. Under prolonged excitation conditions the intensity of the UV output radiation was limited by the permissible heating of the gas to a temperature above which the operating life of the gaseous mixture containing fluorine fell steeply. This was the reason for the advantage of surface over barrier discharges: the former were characterised by a high thermal conductivity of a thin (∼0.2 mm) plasma layer on the surface of the cooled dielectric, which made it possible to construct powerful highly efficient KrF and ArF lamps emitting UV radiation of up to 1 W cm -2 intensity. (laser system components)

  11. Coastal barrier stratigraphy for Holocene high-resolution sea-level reconstruction.

    Costas, Susana; Ferreira, Óscar; Plomaritis, Theocharis A; Leorri, Eduardo

    2016-12-08

    The uncertainties surrounding present and future sea-level rise have revived the debate around sea-level changes through the deglaciation and mid- to late Holocene, from which arises a need for high-quality reconstructions of regional sea level. Here, we explore the stratigraphy of a sandy barrier to identify the best sea-level indicators and provide a new sea-level reconstruction for the central Portuguese coast over the past 6.5 ka. The selected indicators represent morphological features extracted from coastal barrier stratigraphy, beach berm and dune-beach contact. These features were mapped from high-resolution ground penetrating radar images of the subsurface and transformed into sea-level indicators through comparison with modern analogs and a chronology based on optically stimulated luminescence ages. Our reconstructions document a continuous but slow sea-level rise after 6.5 ka with an accumulated change in elevation of about 2 m. In the context of SW Europe, our results show good agreement with previous studies, including the Tagus isostatic model, with minor discrepancies that demand further improvement of regional models. This work reinforces the potential of barrier indicators to accurately reconstruct high-resolution mid- to late Holocene sea-level changes through simple approaches.

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

    2017-07-01

    University of L’Aquila, (2011). 23 Rao, H. & Bosman, G. Hot-electron induced defect generation in AlGaN/GaN high electron mobility transistors. Solid...AFRL-RY-WP-TR-2017-0143 THERMAL INVESTIGATION OF THREE- DIMENSIONAL GaN-on-SiC HIGH ELECTRON MOBILITY TRANSISTORS Qing Hao The University of Arizona...clarification memorandum dated 16 Jan 09. This report is available to the general public, including foreign nationals. Copies may be obtained from the

  13. A review of the Irish road networks infrastructure barriers to older peoples mobility: current policy and literature

    Fenton, Valerie; Caufield, Brian; Ahern, Aoife

    2012-01-01

    Over the next thirty years in Ireland, the population aged over 65 is estimated to grow considerably. The maturation of the ‘baby boom’ generation will transform the demographics of the country. In our current and future aging society, transport and mobility are key factors in facilitating active aging. In general, older people now travel more than before, have higher levels of car ownership and are more likely to continue to drive for longer. Modal shift to more sustainable modes of transpor...

  14. Interaction of a non-histone chromatin protein (high-mobility group protein 2) with DNA

    Goodwin, G.H.; Shooter, K.V.; Johns, E.W.

    1975-01-01

    The interaction with DNA of the calf thymus chromatin non-histone protein termed the high-mobility group protein 2 has been studied by sedimentation analysis in the ultracentrifuge and by measuring the binding of the 125 I-labelled protein to DNA. The results have been compared with those obtained previously by us [Eur. J. Biochem. (1974) 47, 263-270] for the interaction of high-mobility group protein 1 with DNA. Although the binding parameters are similar for these two proteins, high-mobility group protein 2 differs from high-mobility group protein 1 in that the former appears to change the shape of the DNA to a more compact form. The molecular weight of high-mobility group protein 2 has been determined by equilibrium sedimentation and a mean value of 26,000 was obtained. A low level of nuclease activity detected in one preparation of high-mobility group protein 2 has been investigated. (orig.) [de

  15. High-mobility BaSnO{sub 3} grown by oxide molecular beam epitaxy

    Raghavan, Santosh; Schumann, Timo; Kim, Honggyu; Zhang, Jack Y.; Cain, Tyler A.; Stemmer, Susanne, E-mail: stemmer@mrl.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106-5050 (United States)

    2016-01-01

    High-mobility perovskite BaSnO{sub 3} films are of significant interest as new wide bandgap semiconductors for power electronics, transparent conductors, and as high mobility channels for epitaxial integration with functional perovskites. Despite promising results for single crystals, high-mobility BaSnO{sub 3} films have been challenging to grow. Here, we demonstrate a modified oxide molecular beam epitaxy (MBE) approach, which supplies pre-oxidized SnO{sub x}. This technique addresses issues in the MBE of ternary stannates related to volatile SnO formation and enables growth of epitaxial, stoichiometric BaSnO{sub 3}. We demonstrate room temperature electron mobilities of 150 cm{sup 2} V{sup −1} s{sup −1} in films grown on PrScO{sub 3}. The results open up a wide range of opportunities for future electronic devices.

  16. Nonmetallic engineered barriers, their properties and role in a geologic repository for high level radioactive waste

    Lisy, F.

    1994-01-01

    The efficiency of engineered barrier systems depends to a great extent on the properties of the materials used. Backfill and sealing materials must fulfill certain requirements and criteria. They must feature low hydraulic conductivity, high retardation capacity, extremely good sorption properties for a wide range of radionuclides potentially leachable from the deposited waste, low permeability, good compatibility with engineered and natural barriers, good workability, and availability in the necessary quantity and at a reasonable price. Some basic properties are presented of materials which fulfill, to a considerable degree, these requirements and which are thus suggested as suitable backfills, sealings of buffers, namely clay- and cement-based materials (concretes, mortars, etc.). A brief information is also given on some other materials like bitumen, asphalt, etc. (Z.S.) 4 refs

  17. [Mobile-phone e-mail use, social networks, and loneliness among Japanese high school students].

    Ogata, Yasuko; Izumi, Yukiko; Kitaike, Tadashi

    2006-07-01

    The purposes of this study were to assess the loneliness of Japanese high school students who own and use a mobile phone, to clarify the relationships between students' loneliness and their social network and frequency of use of e-mail feature, and to demonstrate relationships with a student's social network and recognition of the benefits and drawbacks of mobile phone use. The participants were 227 students from two classes in each grade of a high school in the Kanto region of Japan. Participants answered a questionnaire covering the UCLA Loneliness Scale as well as questions pertaining to the circumstances of use of their mobile phones, their social networks (e.g., number of friends), and their perceptions of the benefits and drawbacks of mobile phone use. The questionnaires of students owning a mobile phone were analyzed. Total scores for the UCLA Loneliness Scale were calculated, and factor analysis was performed for the benefits and drawbacks. A total of 220 questionnaires were returned, for which 94.1 percent of respondents owned a mobile phone. The percentages of male and female respondents were 58% and 42%. Chronbach's alpha for the UCLA Loneliness Scale (total score) was 0.87, a result similar to previous studies with high school and university students. Factor analysis revealed five factors associated with the benefits and drawbacks of mobile phone use. Multiple-regression analysis showed that 42.9% of the variance in "frequency of e-mail use" was explained by grade level, frequency of mobile phone use, and two of the five factors from the benefits and drawbacks ("difficulty of communication," and "possible sleep loss due to nighttime e-mailing"). Stepwise multiple-regression analysis revealed that 24.4% of the variance in UCLA Loneliness Score was explained by gender, the frequency of e-mail use, the number of friends and the presence/absence of a girlfriend or boyfriend. Presence of an active social network and frequent e-mailing by mobile phone reduced

  18. Performance of high level waste forms and engineered barriers under repository conditions

    1991-02-01

    The IAEA initiated in 1977 a co-ordinated research programme on the ''Evaluation of Solidified High-Level Waste Forms'' which was terminated in 1983. As there was a continuing need for international collaboration in research on solidified high-level waste form and spent fuel, the IAEA initiated a new programme in 1984. The new programme, besides including spent fuel and SYNROC, also placed greater emphasis on the effect of the engineered barriers of future repositories on the properties of the waste form. These engineered barriers included containers, overpacks, buffer and backfill materials etc. as components of the ''near-field'' of the repository. The Co-ordinated Research Programme on the Performance of High-Level Waste Forms and Engineered Barriers Under Repository Conditions had the objectives of promoting the exchange of information on the experience gained by different Member States in experimental performance data and technical model evaluation of solidified high level waste forms, components of the waste package and the complete waste management system under conditions relevant to final repository disposal. The programme includes studies on both irradiated spent fuel and glass and ceramic forms as the final solidified waste forms. The following topics were discussed: Leaching of vitrified high-level wastes, modelling of glass behaviour in clay, salt and granite repositories, environmental impacts of radionuclide release, synroc use for high--level waste solidification, leachate-rock interactions, spent fuel disposal in deep geologic repositories and radionuclide release mechanisms from various fuel types, radiolysis and selective leaching correlated with matrix alteration. Refs, figs and tabs

  19. The ion mobility spectrometer for high explosive vapor detection

    Cohen, M.J.; Stimac, R.M.; Wernlund, R.F.

    1984-01-01

    The Phemto-Chem /SUP R/ Model 100 Ion Mobility Spectrometer (IMS) operates in air and measures a number of explosive vapors at levels as low as partsper-trillion in seconds. The theory and operation of this instrument is discussed. The IMS inhales the vapor sample in a current of air and generates characteristic ions which are separated by time-of -ion drift in the atmospheric pressure gas. Quantitative results, using a dilution tunnel and standard signal generator with TNT, nitroglycerine, ethylene glycol dinitrate, cyclohexanone, methylamine, octafluoronaphthalene and hexafluorobenzene, are given. Rapid sample treatment with sample concentrations, microprocessor signal readout and chemical identification, offer a realistic opportunity of rapid explosive vapor detection at levels down to 10 -14 parts by volume in air

  20. Electrical and optical characteristics of dielectric-barrier discharge driven by high voltage nanosecond generator

    Ahmadeev, V.V.; Kost'yuchenko, S.V.; Kudryavtsev, N.N.; Kurkin, G.A.; Vasilyak, L.M.

    1998-01-01

    Electrical and optical characteristics of the dielectric-barrier discharge in the pressure range of 10-400 Torr were investigated experimentally, particular attention being paid to the discharge homogeneity and to the energy dissipation in the discharge volume. The discharge was driven by a high-voltage pulse generator producing nanosecond high-voltage pulses with an amplitude of 20-30 kV. Air, nitrogen, and helium were used as working gases. The discharge was found to be homogeneous within a wide range of gas pressure. A power density of up to 250 mW/cm 3 has been achieved. (J.U.)

  1. Subthreshold Schottky-barrier thin-film transistors with ultralow power and high intrinsic gain

    Lee, Sungsik; Nathan, Arokia

    2016-10-01

    The quest for low power becomes highly compelling in newly emerging application areas related to wearable devices in the Internet of Things. Here, we report on a Schottky-barrier indium-gallium-zinc-oxide thin-film transistor operating in the deep subthreshold regime (i.e., near the OFF state) at low supply voltages (400) that was both bias and geometry independent. The transistor reported here is useful for sensor interface circuits in wearable devices where high current sensitivity and ultralow power are vital for battery-less operation.

  2. Barriers and Facilitators for the Use of a Medical Mobile App to Prevent Work-Related Risks in Pregnancy: A Qualitative Analysis.

    Velu, Adeline V; van Beukering, Monique Dm; Schaafsma, Frederieke G; Frings-Dresen, Monique Hw; Mol, Ben Wj; van der Post, Joris Am; Kok, Marjolein

    2017-08-22

    The number of women participating in the labor market in Europe has increased over the last several decades. At the same time, there is growing evidence that certain conditions of employment during pregnancy may have a negative influence on pregnancy outcomes. In order to better inform pregnant women, we aim to develop an app to help assess the health risk as a result of personal and work-related factors and provide personal advice for these women and their health care providers. The aim of this study was to compose a thematic overview of the perceived facilitators and barriers according to pregnant women, medical professionals, and employers for the use of a mobile app in obstetrical care to prevent occupational-related pregnancy complications. Two multidisciplinary focus group meetings with in total 14 participants were conducted with pregnant women, occupational physicians, general practitioners, midwives, obstetricians, and representatives of trade unions and employer organizations. Transcripts were analyzed by qualitatively coding procedures and constant comparative methods. We identified 24 potential facilitators and 12 potential barriers for the use of the app in 4 categories: content of the app, the app as a mean to provide information, ease of use, and external factors. The 3 main facilitators identified were the need for a good interaction between the app and the user, apps were viewed as a more practical source of information, and the information should be understandable, according to the existing guidelines, and well-dosed. The 2 main barriers for use were extensive battery and memory use of the smartphone and sending frequent push notifications. The results of this study are important considerations in the developing process of a medical app implementing a guideline or evidence-based information in practice. ©Adeline V Velu, Monique DM van Beukering, Frederieke G Schaafsma, Monique HW Frings-Dresen, Ben WJ Mol, Joris AM van der Post, Marjolein Kok

  3. Reducing Barriers To The Use of High-Efficiency Lighting Systems

    Peter Morante

    2005-12-31

    With funding from the U.S. Department of Energy (DOE), the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute completed the four-year research project, Reducing Barriers to the Use of High-Efficiency Lighting Systems. The initial objectives were: (1) identifying barriers to widespread penetration of lighting controls in commercial/industrial (C/I) applications that employ fluorescent lamp technologies, and (2) making recommendations to overcome these barriers. The addition of a fourth year expanded the original project objectives to include an examination of the impact on fluorescent lamps from dimming utilizing different lamp electrode heating and dimming ratios. The scope of the project was narrowed to identify barriers to the penetration of lighting controls into commercial-industrial (C/I) applications that employ fluorescent lamp technologies, and to recommend means for overcoming these barriers. Working with lighting manufacturers, specifiers, and installers, the project identified technological and marketing barriers to the widespread use of lighting controls, specifically automatic-off controls, occupancy sensors, photosensors, dimming systems, communication protocols and load-shedding ballasts. The primary barriers identified include cost effectiveness of lighting controls to the building owner, lack of standard communication protocols to allow different part of the control system to communicate effectively, and installation and commissioning issues. Overcoming the identified barriers requires lighting control products on the market to achieve three main goals: (1) Achieve sufficient functionality to meet the key requirements of their main market. (2) Allow significant cost reduction compared to current market standard systems. Cost should consider: hardware capital cost including wiring, design time required by the specifier and the control system manufacturer, installation time required by the electrician, and commissioning time and

  4. Knowledge and exercise of human rights, and barriers and facilitators to claiming rights: a cross-sectional study of female sex workers and high-risk men who have sex with men in Andhra Pradesh, India

    Ganju, Deepika; Patel, Sangram Kishor; Prabhakar, Parimi; Adhikary, Rajatashurva

    2016-01-01

    Background HIV prevention interventions recognize the need to protect the rights of key populations and support them to claim their rights as a vulnerability reduction strategy. This study explores knowledge of human rights, and barriers and facilitators to claiming rights, among female sex workers (FSWs) and high-risk men who have sex with men (HR-MSM) who are beneficiaries of a community mobilization intervention in Andhra Pradesh, India. Methods Data are drawn from a cross-sectional survey...

  5. Ionization of water clusters by fast Highly Charged Ions: Stability, fragmentation, energetics and charge mobility

    Legendre, S; Maisonny, R; Capron, M; Bernigaud, V; Cassimi, A; Gervais, B; Grandin, J-P; Huber, B A; Manil, B; Rousseau, P; Tarisien, M; Adoui, L; Lopez-Tarifa, P; AlcamI, M; MartIn, F; Politis, M-F; Penhoat, M A Herve du; Vuilleumier, R; Gaigeot, M-P; Tavernelli, I

    2009-01-01

    We study dissociative ionization of water clusters by impact of fast Ni ions. Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) is used to obtain information about stability, energetics and charge mobility of the ionized clusters. An unusual stability of the (H 2 O) 4 H ''+ ion is observed, which could be the signature of the so called ''Eigen'' structure in gas phase water clusters. High charge mobility, responsible for the formation of protonated water clusters that dominate the mass spectrum, is evidenced. These results are supported by CPMD and TDDFT simulations, which also reveal the mechanisms of such mobility.

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

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

    2014-12-15

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

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

    G. Naresh-Kumar

    2014-12-01

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

  8. Minimized thermal conductivity in highly stable thermal barrier W/ZrO{sub 2} multilayers

    Doering, Florian; Major, Anna; Eberl, Christian; Krebs, Hans-Ulrich [University of Goettingen, Institut fuer Materialphysik, Goettingen (Germany)

    2016-10-15

    Nanoscale thin-film multilayer materials are of great research interest since their large number of interfaces can strongly hinder phonon propagation and lead to a minimized thermal conductivity. When such materials provide a sufficiently small thermal conductivity and feature in addition also a high thermal stability, they would be possible candidates for high-temperature applications such as thermal barrier coatings. For this article, we have used pulsed laser deposition in order to fabricate thin multilayers out of the thermal barrier material ZrO{sub 2} in combination with W, which has both a high melting point and high density. Layer thicknesses were designed such that bulk thermal conductivity is governed by the low value of ZrO{sub 2}, while ultrathin W blocking layers provide a high number of interfaces. By this phonon scattering, reflection and shortening of mean free path lead to a significant reduction in overall thermal conductivity even below the already low value of ZrO{sub 2}. In addition to this, X-ray reflectivity measurements were taken showing strong Bragg peaks even after annealing such multilayers at 1300 K. Those results identify W/ZrO{sub 2} multilayers as desired thermally stable, low-conductivity materials. (orig.)

  9. High-precision high-sensitivity clock recovery circuit for a mobile payment application

    Sun Lichong; Yan Na; Min Hao; Ren Wenliang

    2011-01-01

    This paper presents a fully integrated carrier clock recovery circuit for a mobile payment application. The architecture is based on a sampling-detection module and a charge pump phase locked loop. Compared with clock recovery in conventional 13.56 MHz transponders, this circuit can recover a high-precision consecutive carrier clock from the on/off keying (OOK) signal sent by interrogators. Fabricated by a SMIC 0.18-μm EEPROM CMOS process, this chip works from a single power supply as low as 1.5 V Measurement results show that this circuit provides 0.34% frequency deviation and 8 mV sensitivity. (semiconductor integrated circuits)

  10. High field-effect mobility at the (Sr,Ba)SnO{sub 3}/BaSnO{sub 3} interface

    Fujiwara, Kohei, E-mail: kfujiwara@imr.tohoku.ac.jp; Nishihara, Kazuki; Shiogai, Junichi; Tsukazaki, Atsushi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

    2016-08-15

    A perovskite oxide, BaSnO{sub 3}, has been classified as one of transparent conducting materials with high electron mobility, and its application for field-effect transistors has been the focus of recent research. Here we report transistor operation in BaSnO{sub 3}-based heterostructures with atomically smooth surfaces, fabricated on SrTiO{sub 3} substrates by the (Sr,Ba)SnO{sub 3} buffer technique. Indeed, modulation of band profiles at the channel interfaces with the insertion of wide bandgap (Sr,Ba)SnO{sub 3} as a barrier layer results in a significant improvement of field-effect mobility, implying effective carrier doping at the regulated heterointerface. These results provide an important step towards realization of high-performance BaSnO{sub 3}-based field-effect transistors.

  11. High Temperature Terahertz Detectors Realized by a GaN High Electron Mobility Transistor

    Hou, H. W.; Liu, Z.; Teng, J. H.; Palacios, T.; Chua, S. J.

    2017-04-01

    In this work, a high temperature THz detector based on a GaN high electron mobility transistor (HEMT) with nano antenna structures was fabricated and demonstrated to be able to work up to 200 °C. The THz responsivity and noise equivalent power (NEP) of the device were characterized at 0.14 THz radiation over a wide temperature range from room temperature to 200 °C. A high responsivity Rv of 15.5 and 2.7 kV/W and a low NEP of 0.58 and 10 pW/Hz0.5 were obtained at room temperature and 200 °C, respectively. The advantages of the GaN HEMT over other types of field effect transistors for high temperature terahertz detection are discussed. The physical mechanisms responsible for the temperature dependence of the responsivity and NEP of the GaN HEMT are also analyzed thoroughly.

  12. Design consideration of high voltage Ga2O3 vertical Schottky barrier diode with field plate

    Choi, J.-H.; Cho, C.-H.; Cha, H.-Y.

    2018-06-01

    Gallium oxide (Ga2O3) based vertical Schottky barrier diodes (SBDs) were designed for high voltage switching applications. Since p-type Ga2O3 epitaxy growth or p-type ion implantation technique has not been developed yet, a field plate structure was employed in this study to maximize the breakdown voltage by suppressing the electric field at the anode edge. TCAD simulation was used for the physical analysis of Ga2O3 SBDs from which it was found that careful attention must be paid to the insulator under the field plate. Due to the extremely high breakdown field property of Ga2O3, an insulator with both high permittivity and high breakdown field must be used for the field plate formation.

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

    Hou, Zhipeng

    2015-12-18

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

  14. Diffusion barrier coatings for high temperature corrosion resistance of advanced carbon/carbon composites

    Singh Raman, K.S.

    2000-01-01

    Carbon possesses an excellent combination of mechanical and thermal properties, viz., excellent creep resistance at temperatures up to 2400 deg C in non-oxidizing environment and a low thermal expansion coefficient. These properties make carbon a potential material for very high temperature applications. However, the use of carbon materials at high temperatures is considerably restricted due to their extremely poor oxidation resistance at temperatures above 400 deg C. The obvious choice for improving high temperature oxidation resistance of such materials is a suitable diffusion barrier coating. This paper presents an overview of recent developments in advanced diffusion- and thermal-barrier coatings for ceramic composites, with particular reference to C/C composites. The paper discusses the development of multiphase and multi-component ceramic coatings, and recent investigations on the oxidation resistance of the coated C/C composites. The paper also discusses the cases of innovative engineering solutions for traditional problems with the ceramic coatings, and the scope of intelligent processing in developing coatings for the C/C composites. Copyright (2000) AD-TECH - International Foundation for the Advancement of Technology Ltd

  15. Channel mobility degradation and charge trapping in high-k/metal gate NMOSFETs

    Mathew, Shajan; Bera, L.K.; Balasubramanian, N.; Joo, M.S.; Cho, B.J.

    2004-01-01

    NMOSFETs with Metalo-Organic Chemical Vapor Deposited (MOCVD) HfAlO gate dielectric and TiN metal gate have been fabricated. Channel electron mobility was measured using the split-CV method and compared with SiO 2 devices. All high-k devices showed lower mobility compared with SiO 2 reference devices. High-k MOSFETs exhibited significant charge trapping and threshold instability. Threshold voltage recovery with time was studied on devices with oxide/nitride interfacial layer between high-k film and silicon substrate

  16. An Investigation of the Relationship between High-School Students' Problematic Mobile Phone Use and Their Self-Esteem Levels

    Isiklar, Abdullah; Sar, Ali Haydar; Durmuscelebi, Mustafa

    2013-01-01

    Excessive mobile phone use, especially among adolescents, brings too many debates about its effects. To this end, in this study, we try to investigate the relationship between adolescents' mobile phone use and their self-esteem levels with regard to their genders. For 919 high school students, we evaluated mobile phone use concerning their…

  17. Detuning effect study of High-Q Mobile Phone Antennas

    Bahramzy, Pevand; Pedersen, Gert F.

    2015-01-01

    Number of frequency bands that have to be covered by smart phones, are ever increasing. This broadband coverage can be obtained either by using a low-Q antenna or a high-Q tunable antenna. This study investigates high-Q antennas performance when placed in proximity of the user. This study...

  18. Mobilizing community energy

    Bomberg, Elizabeth; McEwen, Nicola

    2012-01-01

    What explains the galvanising of communities to participate actively in energy projects? How do groups mobilize to overcome the often formidable barriers highlighted in the existing literature? Drawing on original qualitative research of 100 community energy groups in Scotland, including six in-depth case studies, we explain how effective mobilization occurs and the political dynamics surrounding such mobilization. To capture these dynamics, we adapt theories offered by literature on social movements, with a particular focus on resource mobilization theories. Applying our adapted framework, we identify two particular sets of resources shaping community energy mobilization: (i) structural resources, which refer to the broad political context structuring and constraining opportunities for community energy mobilization; and (ii) symbolic resources—less tangible resources used to galvanise participants. We investigate to what extent our case study groups were able to draw upon and exploit these resources. We find that structural resources can either facilitate or hinder mobilization; what matters is how state resources are exploited and constraints mitigated. The use of symbolic resources was highly effective in aiding mobilization. Each of the groups examined – despite their considerable variation – effectively exploited symbolic resources such as shared identity or desire for strong, self reliant communities. - Highlights: ► Explains how/why community energy groups mobilize and the political dynamics surrounding it. ► Draws on original qualitative research of 100 community energy groups in Scotland. ► Identifies two particular sets of resources (structural and symbolic) and their importance. ► Explains how these resources shape community energy mobilization in Scotland. ► Provides an original application of resource mobilization theory to the field of energy studies.

  19. Stability of trans-fermium elements at high spin: Measuring the fission barrier of 254No

    Henning, Greg

    2012-01-01

    Super heavy nuclei provide opportunities to study nuclear structure near three simultaneous limits: in charge Z, spin I and excitation energy E*. These nuclei exist only because of a fission barrier, created by shell effects. It is therefore important to determine the fission barrier and its spin dependence B f (I), which gives information on the shell energy E(shell)(I). Theoretical calculations predict different fission barrier heights from B f (I = 0) = 6.8 MeV for a macro-microscopic model to 8.7 MeV for Density Functional Theory calculations using the Gogny or Skyrme interactions. Hence, a measurement of B f provides a test for theories.To investigate the fission barrier, an established method is to measure the rise of fission with excitation energy, characterized by the ratio of decay widths Γ(fission)/Γ(total), using transfer reactions. However, for heavy elements such as 254 No, there is no suitable target for a transfer reaction. We therefore rely on the complementary decay widths ratio Γ γ /Γ(fission) and its spin dependence, deduced from the entry distribution (I, E*).Measurements of the gamma-ray multiplicity and total energy for 254 No have been performed with beam energies of 219 and 223 MeV in the reaction 208 Pb( 48 Ca,2n) at ATLAS (Argonne Tandem Linac Accelerator System). The 254 No gamma rays were detected using the Gammasphere array as a calorimeter - as well as the usual high resolution γ-ray detector. Coincidences with evaporation residues at the Fragment Mass Analyzer focal plane separated 254 No gamma rays from those from fission fragments, which are ≥ 10 6 more intense. From this measurement, the entry distribution - i.e. the initial distribution of I and E* - is constructed. Each point (I,E*) of the entry distribution is a point where gamma decay wins over fission and, therefore, gives information on the fission barrier. The measured entry distributions show an increase in the maximum spin and excitation energy from 219 to 223 Me

  20. Smart parking barrier

    Alharbi, Abdulrazaq M.

    2016-05-06

    Various methods and systems are provided for smart parking barriers. In one example, among others, a smart parking barrier system includes a movable parking barrier located at one end of a parking space, a barrier drive configured to control positioning of the movable parking barrier, and a parking controller configured to initiate movement of the parking barrier, via the barrier drive. The movable parking barrier can be positioned between a first position that restricts access to the parking space and a second position that allows access to the parking space. The parking controller can initiate movement of the movable parking barrier in response to a positive identification of an individual allowed to use the parking space. The parking controller can identify the individual through, e.g., a RFID tag, a mobile device (e.g., a remote control, smartphone, tablet, etc.), an access card, biometric information, or other appropriate identifier.

  1. Record high hole mobility in polymer semiconductors via side-chain engineering.

    Kang, Il; Yun, Hui-Jun; Chung, Dae Sung; Kwon, Soon-Ki; Kim, Yun-Hi

    2013-10-09

    Charge carrier mobility is still the most challenging issue that should be overcome to realize everyday organic electronics in the near future. In this Communication, we show that introducing smart side-chain engineering to polymer semiconductors can facilitate intermolecular electronic communication. Two new polymers, P-29-DPPDBTE and P-29-DPPDTSE, which consist of a highly conductive diketopyrrolopyrrole backbone and an extended branching-position-adjusted side chain, showed unprecedented record high hole mobility of 12 cm(2)/(V·s). From photophysical and structural studies, we found that moving the branching position of the side chain away from the backbone of these polymers resulted in increased intermolecular interactions with extremely short π-π stacking distances, without compromising solubility of the polymers. As a result, high hole mobility could be achieved even in devices fabricated using the polymers at room temperature.

  2. Pressure tuning of anisotropy barrier in Fe8 SMMs probed using high frequency EPR

    Thirunavukkuarasu, Komalavalli; Beedle, Christopher; Tozer, Stanley; Hill, Stephen

    2014-03-01

    Single-molecule magnets (SMMs) are spin systems with large spin ground state where quantum phenomena such as tunneling of magnetization via a considerable anisotropy barrier manifest. One such SMM that has been extensively studied is [Fe8O2(OH)12(tacn)6]Br8.9H2O, also known as Fe8, with a giant spin ground state of S=10. The eight Fe atoms bridged by the ligands form a butterfly structure where six Fe atoms have spins up and two spins down in the simplest model. This structure in fact gives rise to geometrical spin frustration effects within the cluster. By varying the interaction between the spins, manipulation of quantum tunneling in SMMs may be achieved. Typically, the manipulation of spin interactions is realized using chemical methods. As an alternative approach, we employ high pressure to induce changes in the ligand-field environment of the Fe atoms. In this presentation, the pressure-dependent changes in the anisotropy barrier in single crystal Fe8 SMMs investigated by high frequency electron paramagnetic resonance measurements will be discussed.

  3. Simultaneous realization of high density edge transport barrier and improved L-mode on CHS

    Minami, Takashi; Okamura, Shoichi; Suzuki, Chihiro

    2008-10-01

    An edge transport barrier (ETB) formation and an improved L-mode (IL mode) have been simultaneously realized in high density region (n-bar e - 1.2x10 20 m -3 ) on Compact Helical System (CHS). When the ETB is formed during the IL mode, the density reduction in the edge region is suppressed by the barrier formation. As a result of the continuous increasing of the temperature by the IL mode, the stored energy during the combined mode increased up to the maximum stored energy (W p - 9.4 kJ) recorded in CHS experiments. The plasma pressure in the peripheral region increases up to three times larger than that of the L-mode, and the large edge plasma pressure gradient is formed accompanying the pedestal structure. That is caused by the anomalous transport reduction that is confirmed from the sharp drop of the density fluctuation in the edge region. The neutral particle reduction in the peripheral region and the metallic impurity accumulation in the core plasma are simultaneously observed during the high density ETB formation. (author)

  4. "It's a Way of Life for Us": High Mobility and High Achievement in Department of Defense Schools.

    Smrekar, Claire E.; Owens, Debra E.

    2003-01-01

    Examines the academic performance of students in U.S. Department of Defense Education Activity (DoDEA) schools, which have high student mobility. Some observers contend that these students' high achievement is a function of their middle class family and community characteristics. Asserts that DoDEA schools simultaneously "do the right…

  5. Theoretical prediction of high carrier mobility in single-walled black phosphorus nanotubes

    Li, Q. F.; Wang, H. F.; Yang, C. H.; Li, Q. Q.; Rao, W. F.

    2018-05-01

    One-dimensional semiconductors are promising materials for high-performance nanoscale devices. Using the first-principles calculations combined with deformation potential approximation, we study the electronic structures and carrier transport properties of black phosphorus nanotubes (BPNTs). It is found that both armchair and zigzag BPNTs with diameter 13.5-18.5 Å are direct bandgap semiconductors. At a similar diameter, the carrier mobility of zigzag BPNT is one order of magnitude larger than that of armchair BPNT. For armchair BPNTs, the electron mobility is about 90.70-155.33 cm2 V-1 s-1 at room temperature, which is about three times of its hole counterpart. For zigzag BPNTs, the maximum mobility can reach 2.87 ×103 cm2 V-1 s-1. Furthermore, the electronic properties can be effectively tuned by the strain. For zigzag (0,13) nanotube, there is a direct-to-indirect band gap transition at a tensile strain of about 6%. Moreover, the electron mobility is boosted sharply by one order of magnitude by applying the compressive or tensile strain. The electron mobility increases to 14.05 ×103 cm2 V-1 s-1 at a tensile strain of 9%. Our calculations highlight the tunable electronic properties and superior carrier mobility of BPNTs that are promising for interesting applications in future nano-electronic devices.

  6. Results of Sludge Mobilization Testing at Hanford High Level Waste (HLW) Tank

    STAEHR, T.W.

    2001-01-01

    Waste stored in the Tank 241-AZ-101 at the US DOE Hanford is scheduled as the initial feed for high-level waste vitrification. Tank 241-AZ-101 currently holds over 3,000,000 liters of waste made up of a settled sludge layer covered by a layer of liquid supernant. To retrieve the waste from the tank, it is necessary to mobilize and suspend the settled sludge so that the resulting slurry can be pumped from the tank for treatment and vitrification. Two 223.8-kilowatt mixer pumps have been installed in Tank 241-AZ-101 to mobilize the settled sludge layer of waste for retrieval. In May of 2000, the mixer pumps were subjected to a series of tests to determine (1) the extent to which the mixer pumps could mobilize the settle sludge layer of waste, (2) if the mixer pumps could function within operating parameters, and (3) if state-of-the-art monitoring equipment could effectively monitor and quantify the degree of sludge mobilization and suspension. This paper presents the major findings and results of the Tank 241-AZ-101 mixer pump tests, based on analysis of data and waste samples that were collected during the testing. Discussion of the results focuses on the effective cleaning radius achieved and the volume and concentration of sludge mobilized, with both one and two pumps operating in various configurations and speeds. The Tank 241-AZ-101 mixer pump tests were unique in that sludge mobilization parameters were measured using actual waste in an underground storage tank at the hanford Site. The methods and instruments that were used to measure waste mobilization parameters in Tank 241-AZ-101 can be used in other tanks. It can be concluded from the testing that the use of mixer pumps is an effective retrieval method for the mobilization of settled solids in Tank 241-AZ-101

  7. GENERATION OF HIGH RESOLUTION AND HIGH PRECISION ORTHORECTIFIED ROAD IMAGERY FROM MOBILE MAPPING SYSTEM

    M. Sakamoto

    2012-07-01

    Full Text Available In this paper, a novel technique to generate a high resolution and high precision Orthorectified Road Imagery (ORI by using spatial information acquired from a Mobile Mapping System (MMS is introduced. The MMS was equipped with multiple sensors such as GPS, IMU, odometer, 2-6 digital cameras and 2-4 laser scanners. In this study, a Triangulated Irregular Network (TIN based approach, similar to general aerial photogrammetry, was adopted to build a terrain model in order to generate ORI with high resolution and high geometric precision. Compared to aerial photogrammetry, there are several issues that are needed to be addressed. ORI is generated by merging multiple time sequence images of a short section. Hence, the influence of occlusion due to stationary objects, such as telephone poles, trees, footbridges, or moving objects, such as vehicles, pedestrians are very significant. Moreover, influences of light falloff at the edges of cameras, tone adjustment among images captured from different cameras or a round trip data acquisition of the same path, and time lag between image exposure and laser point acquisition also need to be addressed properly. The proposed method was applied to generate ORI with 1 cm resolution, from the actual MMS data sets. The ORI generated by the proposed technique was more clear, occlusion free and with higher resolution compared to the conventional orthorectified coloured point cloud imagery. Moreover, the visual interpretation of road features from the ORI was much easier. In addition, the experimental results also validated the effectiveness of proposed radiometric corrections. In occluded regions, the ORI was compensated by using other images captured from different angles. The validity of the image masking process, in the occluded regions, was also ascertained.

  8. Subsurface barrier design alternatives for confinement and controlled advection flow

    Phillips, S.J.; Stewart, W.E.; Alexander, R.G.; Cantrell, K.J.; McLaughlin, T.J.

    1994-02-01

    Various technologies and designs are being considered to serve as subsurface barriers to confine or control contaminant migration from underground waste storage or disposal structures containing radioactive and hazardous wastes. Alternatives including direct-coupled flood and controlled advection designs are described as preconceptual examples. Prototype geotechnical equipment for testing and demonstration of these alternative designs tested at the Hanford Geotechnical Development and Test Facility and the Hanford Small-Tube Lysimeter Facility include mobile high-pressure injectors and pumps, mobile transport and pumping units, vibratory and impact pile drivers, and mobile batching systems. Preliminary laboratory testing of barrier materials and additive sequestering agents have been completed and are described

  9. From computational discovery to experimental characterization of a high hole mobility organic crystal.

    Sokolov, Anatoliy N

    2011-08-16

    For organic semiconductors to find ubiquitous electronics applications, the development of new materials with high mobility and air stability is critical. Despite the versatility of carbon, exploratory chemical synthesis in the vast chemical space can be hindered by synthetic and characterization difficulties. Here we show that in silico screening of novel derivatives of the dinaphtho[2,3-b:2\\',3\\'-f]thieno[3,2-b]thiophene semiconductor with high hole mobility and air stability can lead to the discovery of a new high-performance semiconductor. On the basis of estimates from the Marcus theory of charge transfer rates, we identified a novel compound expected to demonstrate a theoretic twofold improvement in mobility over the parent molecule. Synthetic and electrical characterization of the compound is reported with single-crystal field-effect transistors, showing a remarkable saturation and linear mobility of 12.3 and 16 cm(2) V(-1) s(-1), respectively. This is one of the very few organic semiconductors with mobility greater than 10 cm(2) V(-1) s(-1) reported to date.

  10. A high mobility C60 field-effect transistor with an ultrathin pentacene passivation layer and bathophenanthroline/metal bilayer electrodes

    Zhou Jian-Lin; Yu Jun-Sheng; Yu Xin-Ge; Cai Xin-Yang

    2012-01-01

    C 60 field-effect transistor (OFET) with a mobility as high as 5.17 cm 2 /V·s is fabricated. In our experiment, an ultrathin pentacene passivation layer on poly-(methyl methacrylate) (PMMA) insulator and a bathophenanthroline (Bphen)/Ag bilayer electrode are prepared. The OFET shows a significant enhancement of electron mobility compared with the corresponding device with a single PMMA insultor and an Ag electrode. By analysing the C 60 film with atomic force microscopy and X-ray diffraction techniques, it is shown that the pentacene passivation layer can contribute to C 60 film growth with the large grain size and significantly improve crystallinity. Moreover, the Bphen buffer layer can reduce the electron contact barrier from Ag electrodes to C 60 film efficiently. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. Unveiling the Structural Origin of the High Carrier Mobility of a Molecular Monolayer on Boron Nitride

    Xu, Rui; He, Daowei; Zhang, Yuhan; Wu, Bing; Liu, Fengyuan; Meng, Lan; Liu, Jun-Fang; Wu, Qisheng; Shi, Yi; Wang, Jinlan; Nie, Jia-Cai; Wang, Xinran; He, Lin

    2014-01-01

    Very recently, it was demonstrated that the carrier mobility of a molecular monolayer dioctylbenzothienobenzothiophene (C8-BTBT) on boron nitride can reach 10 cm2/Vs, the highest among the previously reported monolayer molecular field-effect transistors. Here we show that the high-quality single crystal of the C8-BTBT monolayer may be the key origin of the record-high carrier mobility. We discover that the C8-BTBT molecules prefer layer-by-layer growth on both hexagonal boron nitride and grap...

  12. High-Performance Ink-Synthesized Cu-Gate Thin-Film Transistor with Diffusion Barrier Formation

    Woo, Whang Je; Nam, Taewook; Oh, Il-Kwon; Maeng, Wanjoo; Kim, Hyungjun

    2018-05-01

    The improved electrical properties of Cu-gate thin-film transistors (TFTs) using an ink-synthesizing process were studied; this technology enables a low-cost and large area process for the display industry. We investigated the film properties and the effects of the ink-synthesized Cu layer in detail with respect to device characteristics. The mobility and reliability of the devices were significantly improved by applying a diffusion barrier at the interface between the Cu gate and the gate insulator. By using a TaN diffusion barrier layer, considerably improved and stabilized ink-Cu gated TFTs could be realized, comparable to sputtered-Cu gated TFTs under positive bias temperature stress measurements.

  13. High-Performance Ink-Synthesized Cu-Gate Thin-Film Transistor with Diffusion Barrier Formation

    Woo, Whang Je; Nam, Taewook; Oh, Il-Kwon; Maeng, Wanjoo; Kim, Hyungjun

    2018-02-01

    The improved electrical properties of Cu-gate thin-film transistors (TFTs) using an ink-synthesizing process were studied; this technology enables a low-cost and large area process for the display industry. We investigated the film properties and the effects of the ink-synthesized Cu layer in detail with respect to device characteristics. The mobility and reliability of the devices were significantly improved by applying a diffusion barrier at the interface between the Cu gate and the gate insulator. By using a TaN diffusion barrier layer, considerably improved and stabilized ink-Cu gated TFTs could be realized, comparable to sputtered-Cu gated TFTs under positive bias temperature stress measurements.

  14. Feasibility of using a high-level waste canister as an engineered barrier in disposal

    Slate, S.C.; Pitman, S.G.; Nesbitt, J.F.; Partain, W.L.

    1982-08-01

    The objective of this report is to evaluate the feasibility of designing a process canister that could also serve as a barrier canister. To do this a general set of performance criteria is assumed and several metal alloys having a high probability of demonstrating high corrosion resistance under repository conditions are evaluated in a qualitative design assessment. This assessment encompasses canister manufacture, the glass-filling process, interim storage, transportation, and to a limited extent, disposal in a repository. A series of scoping tests were carried out on two titanium alloys and Inconel 625 to determine if the high temperature inherent in the glass-fill processing would seriously affect either the strength or corrosion resistance of these metals. This is a process-related concern unique to the barrier canister concept. The material properties were affected by the heat treatments which simulated both the joule-heated glass melter process (titanium alloys and Inconel 625) and the in-can melter (ICM) process (Inconel 625). However, changes in the material properties were generally within 20% of the original specimens. Accelerated corrosion testing of the heat treated coupons in a highly oxygenated brine showed basic corrosion resistance of titanium grade 12 and Inconel 625 to compare favorably with that of the untreated coupons. The titanium grade 2 coupons experienced severe corrosion pitting. These corrosion tests were of a scoping nature and suitable primarily for the detection of gross sensitivity to the heat treatment inherent in the glass-fill process. They are only suggstive of repository performance since the tests do not adequately model the wide range of repository conditions that could conceivably occur

  15. Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures.

    Schuster, Ann-Christin; Burghardt, Markus; Alfarhan, Ahmed; Bueno, Amauri; Hedrich, Rainer; Leide, Jana; Thomas, Jacob; Riederer, Markus

    2016-01-01

    Maintaining the integrity of the cuticular transpiration barrier even at elevated temperatures is of vital importance especially for hot-desert plants. Currently, the temperature dependence of the leaf cuticular water permeability and its relationship with the chemistry of the cuticles are not known for a single desert plant. This study investigates whether (i) the cuticular permeability of a desert plant is lower than that of species from non-desert habitats, (ii) the temperature-dependent increase of permeability is less pronounced than in those species and (iii) whether the susceptibility of the cuticular permeability barrier to high temperatures is related to the amounts or properties of the cutin or the cuticular waxes. We test these questions with Rhazya stricta using the minimum leaf water vapour conductance (gmin) as a proxy for cuticular water permeability. gmin of R. stricta (5.41 × 10(-5) m s(-1) at 25 °C) is in the upper range of all existing data for woody species from various non-desert habitats. At the same time, in R. stricta, the effect of temperature (15-50 °C) on gmin (2.4-fold) is lower than in all other species (up to 12-fold). Rhazya stricta is also special since the temperature dependence of gmin does not become steeper above a certain transition temperature. For identifying the chemical and physical foundation of this phenomenon, the amounts and the compositions of cuticular waxes and cutin were determined. The leaf cuticular wax (251.4 μg cm(-2)) is mainly composed of pentacyclic triterpenoids (85.2% of total wax) while long-chain aliphatics contribute only 3.4%. In comparison with many other species, the triterpenoid-to-cutin ratio of R. stricta (0.63) is high. We propose that the triterpenoids deposited within the cutin matrix restrict the thermal expansion of the polymer and, thus, prevent thermal damage to the highly ordered aliphatic wax barrier even at high temperatures. Published by Oxford University Press on behalf of the

  16. Diketopyrrolopyrrole-diketopyrrolopyrrole-based conjugated copolymer for high-mobility organic field-effect transistors

    Kanimozhi, Catherine K.

    2012-10-10

    In this communication, we report the synthesis of a novel diketopyrrolopyrrole-diketopyrrolopyrrole (DPP-DPP)-based conjugated copolymer and its application in high-mobility organic field-effect transistors. Copolymerization of DPP with DPP yields a copolymer with exceptional properties such as extended absorption characteristics (up to ∼1100 nm) and field-effect electron mobility values of >1 cm 2 V -1 s -1. The synthesis of this novel DPP-DPP copolymer in combination with the demonstration of transistors with extremely high electron mobility makes this work an important step toward a new family of DPP-DPP copolymers for application in the general area of organic optoelectronics. © 2012 American Chemical Society.

  17. Followup Audit: DLA Officials Took Appropriate Actions to Address Concerns With Repair Parts for the High Mobility Multipurpose Wheeled Vehicle

    2016-04-29

    Followup Audit : DLA Officials Took Appropriate Actions to Address Concerns With Repair Parts for the High Mobility Multipurpose Wheeled Vehicle A P R I L...Results in Brief Followup Audit : DLA Officials Took Appropriate Actions to Address Concerns With Repair Parts for the High Mobility Multipurpose Wheeled...and Maritime Paid Too Much for High Mobility Multipurpose Wheeled Vehicle Repair Parts,” (HMMWV) was issued on April 4, 2014. The audit

  18. Execution techniques for high level radioactive waste disposal. 4. Design and manufacturing procedure of engineered barriers

    Ogata, Nobuhide; Kosaki, Akio; Ueda, Hiroyoshi; Asano, Hidekazu; Takao, Hajime

    1999-01-01

    Ensuring the physical integrity of engineered barriers for an extremely long time period is necessary for geological disposal of high-level radioactive wastes. This report describes the design process and the designed configurations of both overpack and buffer as engineered barriers. Manufacturing procedure, quality control and inspection methods are also summarized. Carbon steel was selected as a structural material of the overpack and the specification of the overpack was determined assuming disposal in the depths of 1000 m below surface of crystalline rock site. The mixture of bentonite and sand (80% sodium bentonite and 20% silica sand by mass) was selected as material for a buffer from mainly its permeability and characteristics of self-sealing of a gap occurred in construction work. Welding method of a lid onto the main body of the overpack, uniting method of a corrosion-resistance layer and the structural component in the case of a composite overpack and manufacturing procedures of both blocks-type and monolithic-type buffers are also investigated. (author)

  19. Anticipated Degradation Modes of Metallic Engineered Barriers for High-Level Nuclear Waste Repositories

    Rodríguez, Martín A.

    2014-03-01

    Metallic engineered barriers must provide a period of absolute containment to high-level radioactive waste in geological repositories. Candidate materials include copper alloys, carbon steels, stainless steels, nickel alloys, and titanium alloys. The national programs of nuclear waste management have to identify and assess the anticipated degradation modes of the selected materials in the corresponding repository environment, which evolves in time. Commonly assessed degradation modes include general corrosion, localized corrosion, stress-corrosion cracking, hydrogen-assisted cracking, and microbiologically influenced corrosion. Laboratory testing and modeling in metallurgical and environmental conditions of similar and higher aggressiveness than those expected in service conditions are used to evaluate the corrosion resistance of the materials. This review focuses on the anticipated degradation modes of the selected or reference materials as corrosion-resistant barriers in nuclear repositories. These degradation modes depend not only on the selected alloy but also on the near-field environment. The evolution of the near-field environment varies for saturated and unsaturated repositories considering backfilled and unbackfilled conditions. In saturated repositories, localized corrosion and stress-corrosion cracking may occur in the initial aerobic stage, while general corrosion and hydrogen-assisted cracking are the main degradation modes in the anaerobic stage. Unsaturated repositories would provide an oxidizing environment during the entire repository lifetime. Microbiologically influenced corrosion may be avoided or minimized by selecting an appropriate backfill material. Radiation effects are negligible provided that a thick-walled container or an inner shielding container is used.

  20. High Magnetic Field in THz Plasma Wave Detection by High Electron Mobility Transistors

    Sakowicz, M.; Łusakowski, J.; Karpierz, K.; Grynberg, M.; Valusis, G.

    The role of gated and ungated two dimensional (2D) electron plasma in THz detection by high electron mobility transistors (HEMTs) was investigated. THz response of GaAs/AlGaAs and GaN/AlGaN HEMTs was measured at 4.4K in quantizing magnetic fields with a simultaneous modulation of the gate voltage UGS. This allowed us to measure both the detection signal, S, and its derivative dS/dUGS. Shubnikov - de-Haas oscillations (SdHO) of both S and dS/dUGS were observed. A comparison of SdHO observed in detection and magnetoresistance measurements allows us to associate unambiguously SdHO in S and dS/dUGS with the ungated and gated parts of the transistor channel, respectively. This allows us to conclude that the entire channel takes part in the detection process. Additionally, in the case of GaAlAs/GaAs HEMTs, a structure related to the cyclotron resonance transition was observed.

  1. High Expression of High-Mobility Group Box 1 in Menstrual Blood: Implications for Endometriosis.

    Shimizu, Keiko; Kamada, Yasuhiko; Sakamoto, Ai; Matsuda, Miwa; Nakatsuka, Mikiya; Hiramatsu, Yuji

    2017-11-01

    Endometriosis is a benign gynecologic disease characterized by the presence of ectopic endometrium and associated with inflammation and immune abnormalities. However, the molecular basis for endometriosis is not well understood. To address this issue, the present study examined the expression of high-mobility group box (HMGB) 1 in menstrual blood to investigate its role in the ectopic growth of human endometriotic stromal cells (ESCs). A total of 139 patients were enrolled in this study; 84 had endometriosis and 55 were nonendometriotic gynecological patients (control). The HMGB1 levels in various fluids were measured by enzyme-linked immunosorbent assay. Expression of receptor for advanced glycation end products (RAGE) in eutopic and ectopic endometrium was assessed by immunohistochemistry, and RAGE and vascular endothelial growth factor ( VEGF) messenger RNA expression in HMGB1- and lipopolysaccharide (LPS)-treated ESCs was evaluated by real-time polymerase chain reaction. The HMGB1 concentration was higher in menstrual blood than in serum or peritoneal fluid ( P endometriosis following retrograde menstruation when complexed with other factors such as LPS by inducing inflammation and angiogenesis.

  2. Dynamic simulation of collisions of heavy high-speed trucks with concrete barriers

    Itoh, Yoshito; Liu, Chunlu; Kusama, Ryuichi

    2007-01-01

    Real vehicle collision experiments on full-scale road safety barriers are important to determine the outcome of a vehicle versus barrier impact accident. However, such experiments require large investment of time and money. Numerical simulation has therefore been imperative as an alternative method for testing concrete barriers. In this research, spring subgrade models were first developed to simulate the ground boundary of concrete barriers. Both heavy trucks and concrete barriers were modeled using finite element methods (FEM) to simulate dynamic collision performances. Comparison of the results generated from computer simulations and on-site full-scale experiments demonstrated that the developed models could be applied to simulate the collision of heavy trucks with concrete barriers to provide the data to design new road safety barriers and analyze existing ones

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

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

    2016-01-04

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

  4. Comprehensive review on the development of high mobility in oxide thin film transistors

    Choi, Jun Young; Lee, Sang Yeol

    2017-11-01

    Oxide materials are one of the most advanced key technology in the thin film transistors (TFTs) for the high-end of device applications. Amorphous oxide semiconductors (AOSs) have leading technique for flat panel display (FPD), active matrix organic light emitting display (AMOLED) and active matrix liquid crystal display (AMLCD) due to their excellent electrical characteristics, such as field effect mobility ( μ FE ), subthreshold swing (S.S) and threshold voltage ( V th ). Covalent semiconductor like amorphous silicon (a-Si) is attributed to the anti-bonding and bonding states of Si hybridized orbitals. However, AOSs have not grain boundary and excellent performances originated from the unique characteristics of AOS which is the direct orbital overlap between s orbitals of neighboring metal cations. High mobility oxide TFTs have gained attractive attention during the last few years and today in display industries. It is progressively developed to increase the mobility either by exploring various oxide semiconductors or by adopting new TFT structures. Mobility of oxide thin film transistor has been rapidly increased from single digit to higher than 100 cm2/V·s in a decade. In this review, we discuss on the comprehensive review on the mobility of oxide TFTs in a decade and propose bandgap engineering and novel structure to enhance the electrical characteristics of oxide TFTs.

  5. High-skilled labour mobility in Europe before and after the 2004 enlargement.

    Petersen, Alexander M; Puliga, Michelangelo

    2017-03-01

    The extent to which international high-skilled mobility channels are forming is a question of great importance in an increasingly global knowledge-based economy. One factor facilitating the growth of high-skilled labour markets is the standardization of certifiable degrees meriting international recognition. Within this context, we analysed an extensive high-skilled mobility database comprising roughly 382 000 individuals from five broad profession groups (Medical, Education, Technical, Science & Engineering and Business & Legal) over the period 1997-2014, using the 13-country expansion of the European Union (EU) to provide insight into labour market integration. We compare the periods before and after the 2004 enlargement, showing the emergence of a new east-west migration channel between the 13 mostly eastern EU entrants (E) and the rest of the western European countries (W). Indeed, we observe a net directional loss of human capital from E → W, representing 29% of the total mobility after 2004. Nevertheless, the counter-migration from W → E is 7% of the total mobility over the same period, signalling the emergence of brain circulation within the EU. Our analysis of the country-country mobility networks and the country-profession bipartite networks provides timely quantitative evidence for the convergent integration of the EU, and highlights the central role of the UK and Germany as high-skilled labour hubs. We conclude with two data-driven models to explore the structural dynamics of the mobility networks. First, we develop a reconfiguration model to explore the potential ramifications of Brexit and the degree to which redirection of high-skilled labourers away from the UK may impact the integration of the rest of the European mobility network. Second, we use a panel regression model to explain empirical high-skilled mobility rates in terms of various economic 'push-pull' factors, the results of which show that government expenditure on education, per capita

  6. Electron density and currents of AlN/GaN high electron mobility transistors with thin GaN/AlN buffer layer

    Bairamis, A.; Zervos, Ch.; Georgakilas, A.; Adikimenakis, A.; Kostopoulos, A.; Kayambaki, M.; Tsagaraki, K.; Konstantinidis, G.

    2014-01-01

    AlN/GaN high electron mobility transistor (HEMT) structures with thin GaN/AlN buffer layer have been analyzed theoretically and experimentally, and the effects of the AlN barrier and GaN buffer layer thicknesses on two-dimensional electron gas (2DEG) density and transport properties have been evaluated. HEMT structures consisting of [300 nm GaN/ 200 nm AlN] buffer layer on sapphire were grown by plasma-assisted molecular beam epitaxy and exhibited a remarkable agreement with the theoretical calculations, suggesting a negligible influence of the crystalline defects that increase near the heteroepitaxial interface. The 2DEG density varied from 6.8 × 10 12 to 2.1 × 10 13 cm −2 as the AlN barrier thickness increased from 2.2 to 4.5 nm, while a 4.5 nm AlN barrier would result to 3.1 × 10 13 cm −2 on a GaN buffer layer. The 3.0 nm AlN barrier structure exhibited the highest 2DEG mobility of 900 cm 2 /Vs for a density of 1.3 × 10 13 cm −2 . The results were also confirmed by the performance of 1 μm gate-length transistors. The scaling of AlN barrier thickness from 1.5 nm to 4.5 nm could modify the drain-source saturation current, for zero gate-source voltage, from zero (normally off condition) to 0.63 A/mm. The maximum drain-source current was 1.1 A/mm for AlN barrier thickness of 3.0 nm and 3.7 nm, and the maximum extrinsic transconductance was 320 mS/mm for 3.0 nm AlN barrier.

  7. Electron density and currents of AlN/GaN high electron mobility transistors with thin GaN/AlN buffer layer

    Bairamis, A.; Zervos, Ch.; Georgakilas, A., E-mail: alexandr@physics.uoc.gr [Microelectronics Research Group, IESL, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1385, GR-71110 Heraklion, Crete (Greece); Department of Physics, University of Crete, P.O. Box 2208, GR-71003 Heraklion, Crete (Greece); Adikimenakis, A.; Kostopoulos, A.; Kayambaki, M.; Tsagaraki, K.; Konstantinidis, G. [Microelectronics Research Group, IESL, Foundation for Research and Technology-Hellas (FORTH), P.O. Box 1385, GR-71110 Heraklion, Crete (Greece)

    2014-09-15

    AlN/GaN high electron mobility transistor (HEMT) structures with thin GaN/AlN buffer layer have been analyzed theoretically and experimentally, and the effects of the AlN barrier and GaN buffer layer thicknesses on two-dimensional electron gas (2DEG) density and transport properties have been evaluated. HEMT structures consisting of [300 nm GaN/ 200 nm AlN] buffer layer on sapphire were grown by plasma-assisted molecular beam epitaxy and exhibited a remarkable agreement with the theoretical calculations, suggesting a negligible influence of the crystalline defects that increase near the heteroepitaxial interface. The 2DEG density varied from 6.8 × 10{sup 12} to 2.1 × 10{sup 13} cm{sup −2} as the AlN barrier thickness increased from 2.2 to 4.5 nm, while a 4.5 nm AlN barrier would result to 3.1 × 10{sup 13} cm{sup −2} on a GaN buffer layer. The 3.0 nm AlN barrier structure exhibited the highest 2DEG mobility of 900 cm{sup 2}/Vs for a density of 1.3 × 10{sup 13} cm{sup −2}. The results were also confirmed by the performance of 1 μm gate-length transistors. The scaling of AlN barrier thickness from 1.5 nm to 4.5 nm could modify the drain-source saturation current, for zero gate-source voltage, from zero (normally off condition) to 0.63 A/mm. The maximum drain-source current was 1.1 A/mm for AlN barrier thickness of 3.0 nm and 3.7 nm, and the maximum extrinsic transconductance was 320 mS/mm for 3.0 nm AlN barrier.

  8. A transfer technique for high mobility graphene devices on commercially available hexagonal boron nitride

    Zomer, P. J.; Dash, S. P.; Tombros, N.; van Wees, B. J.

    2011-01-01

    We present electronic transport measurements of single and bilayer graphene on commercially available hexagonal boron nitride. We extract mobilities as high as 125 000 cm(2) V-1 s(-1) at room temperature and 275 000 cm(2) V-1 s(-1) at 4.2 K. The excellent quality is supported by the early

  9. Atomic layer deposition of high-mobility hydrogen-doped zinc oxide

    Macco, B.; Knoops, H.C.M.; Verheijen, M.A.; Beyer, W.; Creatore, M.; Kessels, W.M.M.

    2017-01-01

    In this work, atomic layer deposition (ALD) has been employed to prepare high-mobility H-doped zinc oxide (ZnO:H) films. Hydrogen doping was achieved by interleaving the ZnO ALD cycles with H2 plasma treatments. It has been shown that doping with H2 plasma offers key advantages over traditional

  10. High mobility group A1 enhances tumorigenicity of human cholangiocarcinoma and confers resistance to therapy

    Quintavalle, Cristina; Burmeister, Katharina; Piscuoglio, Salvatore

    2017-01-01

    High mobility group A1 (HMGA1) protein has been described to play an important role in numerous types of human carcinoma. By the modulation of several target genes HMGA1 promotes proliferation and epithelial-mesenchymal transition of tumor cells. However, its role in cholangiocarcinoma (CCA) has...

  11. Considering the Geographic Dispersion of Homeless and Highly Mobile Students and Families

    Miller, Peter M.; Bourgeois, Alexis K.

    2013-01-01

    This article addresses school and community-level issues associated with the expanding crisis of student homelessness in the United States. We note that while an increased geographic dispersion of homeless and highly mobile (HHM) families is largely attributed to the widespread effects of the economic recession, it is also furthered by shifting…

  12. An Exploration of Teacher Attrition and Mobility in High Poverty Racially Segregated Schools

    Djonko-Moore, Cara M.

    2016-01-01

    The purpose of this study was to examine the mobility (movement to a new school) and attrition (quitting teaching) patterns of teachers in high poverty, racially segregated (HPRS) schools in the US. Using 2007-9 survey data from the National Center for Education Statistics, a multi-level multinomial logistic regression was performed to examine the…

  13. Using Mobile Communication Technology in High School Education: Motivation, Pressure, and Learning Performance

    Rau, Pei-Luen Patrick; Gao, Qin; Wu, Li-Mei

    2008-01-01

    Motivation and pressure are considered two factors impacting vocational senior high school student learning. New communication technology, especially mobile communication technology, is supposed to be effective in encouraging interaction between the student and the instructor and improving learning efficiency. Social presence and information…

  14. Integrating mHealth Mobile Applications to Reduce High Risk Drinking among Underage Students

    Kazemi, Donna M.; Cochran, Allyson R.; Kelly, John F.; Cornelius, Judith B.; Belk, Catherine

    2014-01-01

    Objective: College students embrace mobile cell phones (MCPs) as a primary communication and entertainment device. The aim of this study was to investigate college students' perceptions toward using mHealth technology to deliver interventions to prevent high-risk drinking and associated consequences. Design/setting: Four focus group interviews…

  15. CityMobil : Human factor issues regarding highly automated vehicles on eLane

    Toffetti, A.; Wilschut, E.S.; Martens, M.H.; Schieben, A.; Rambaldini, A.; Merat, N.; Flemisch, F.

    2009-01-01

    There are several human factor concerns with highly autonomous or semiautonomous driving, such as transition of control, loss of skill, and dealing with automated system errors. Four CityMobil experiments studied the eLane concept for dual-mode cars, and the results of one are described. The open

  16. High School Pupils' Attitudes and Self-Efficacy of Using Mobile Devices

    Nikolopoulou, Kleopatra; Gialamas, Vasilis

    2017-01-01

    This paper regards a study aiming to investigate junior high school pupils' attitudes and self-efficacy of using mobile devices. A 25-item questionnaire was administered to 260 pupils aged 12-15 years old, in Greece. Pupils' attitudes were positive, and four factors were extracted, "perceived usefulness", "affection",…

  17. From computational discovery to experimental characterization of a high hole mobility organic crystal.

    Sokolov, Anatoliy N; Atahan-Evrenk, Sule; Mondal, Rajib; Akkerman, Hylke B; Sá nchez-Carrera, Roel S; Granados-Focil, Sergio; Schrier, Joshua; Mannsfeld, Stefan C B; Zoombelt, Arjan P; Bao, Zhenan; Aspuru-Guzik, Alá n

    2011-01-01

    can be hindered by synthetic and characterization difficulties. Here we show that in silico screening of novel derivatives of the dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene semiconductor with high hole mobility and air stability can lead

  18. A survey study of the association between mobile phone use and daytime sleepiness in California high school students.

    Nathan, Nila; Zeitzer, Jamie

    2013-09-12

    Mobile phone use is near ubiquitous in teenagers. Paralleling the rise in mobile phone use is an equally rapid decline in the amount of time teenagers are spending asleep at night. Prior research indicates that there might be a relationship between daytime sleepiness and nocturnal mobile phone use in teenagers in a variety of countries. As such, the aim of this study was to see if there was an association between mobile phone use, especially at night, and sleepiness in a group of U.S. teenagers. A questionnaire containing an Epworth Sleepiness Scale (ESS) modified for use in teens and questions about qualitative and quantitative use of the mobile phone was completed by students attending Mountain View High School in Mountain View, California (n = 211). Multivariate regression analysis indicated that ESS score was significantly associated with being female, feeling a need to be accessible by mobile phone all of the time, and a past attempt to reduce mobile phone use. The number of daily texts or phone calls was not directly associated with ESS. Those individuals who felt they needed to be accessible and those who had attempted to reduce mobile phone use were also ones who stayed up later to use the mobile phone and were awakened more often at night by the mobile phone. The relationship between daytime sleepiness and mobile phone use was not directly related to the volume of texting but may be related to the temporal pattern of mobile phone use.

  19. Sintering Characteristics of Multilayered Thermal Barrier Coatings Under Thermal Gradient and Isothermal High Temperature Annealing Conditions

    Rai, Amarendra K.; Schmitt, Michael P.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    Pyrochlore oxides have most of the relevant attributes for use as next generation thermal barrier coatings such as phase stability, low sintering kinetics and low thermal conductivity. One of the issues with the pyrochlore oxides is their lower toughness and therefore higher erosion rate compared to the current state-of-the-art TBC material, yttria (6 to 8 wt%) stabilized zirconia (YSZ). In this work, sintering characteristics were investigated for novel multilayered coating consisted of alternating layers of pyrochlore oxide viz Gd2Zr2O7 and t' low k (rare earth oxide doped YSZ). Thermal gradient and isothermal high temperature (1316 C) annealing conditions were used to investigate sintering and cracking in these coatings. The results are then compared with that of relevant monolayered coatings and a baseline YSZ coating.

  20. Highly ordered self-assembling polymer/clay nanocomposite barrier film.

    Cook, Ray; Chen, Yihong; Beall, Gary W

    2015-05-27

    Efforts to mimic complex-structured biologically based materials such as abalone shell have occupied substantial research time and effort in science and engineering. The majority of the efforts involve tedious and expensive techniques and processes. Layer-by-layer (LBL) is one such technique that can produce materials with quite unique physical properties, approaching, and in some cases surpassing, those seen in nature. The LBL technique, however, is quite tedious and difficult to implement commercially. We report here the discovery of an organic/inorganic spontaneous self-assembling system that forms a highly structured nanocomposite. The driving force behind this self-assembly appears to be entropy. This discovery should open up completely new avenues to designing hierarchical composites and structures. The films have been studied by X-ray diffraction and the barrier properties for oxygen diffusion measured.

  1. Fabrication of 4H-SiC Schottky barrier diodes with high breakdown voltages

    Kum, B H; Shin, M W; Park, J D

    1999-01-01

    This paper discusses the fabrication and the breakdown characteristics of 4H-SiC Schottky barrier diodes (SBDs). Optimal processing conditions for the ohmic contacts were extracted using the transmission-line method (TLM) and were applied to the device fabrication. The Ti/4H-SiC SBDs with Si sub x B sub y passivation showed a maximum reverse breakdown voltage of 268 V with a forward current density as high as 70 mA/cm sup 2 at a forward voltage of 2 V. The breakdown of the Pt. 4H-SiC SBDs without any passivation occurred at near 110 V. It is concluded that the breakdown enhancement in the Ti/4H-SiC SBDs can be attributed to the passivation; otherwise, excess surface charge near the edge of the Schottky contact would lead to electric fields of sufficient magnitude to cause field emission.

  2. High-efficiency dielectric barrier Xe discharge lamp: theoretical and experimental investigations

    Beleznai, Sz; Mihajlik, G; Agod, A; Maros, I; Juhasz, R; Nemeth, Zs; Jakab, L; Richter, P

    2006-01-01

    A dielectric barrier Xe discharge lamp producing vacuum-ultraviolet radiation with high efficiency was investigated theoretically and experimentally. The cylindrical glass body of the lamp is equipped with thin strips of metal electrodes applied to diametrically opposite sides of the outer surface. We performed a simulation of discharge plasma properties based on one-dimensional fluid dynamics and also assessed the lamp characteristics experimentally. Simulation and experimental results are analysed and compared in terms of voltage and current characteristics, power input and discharge efficiency. Using the proposed lamp geometry and fast rise-time short square pulses of the driving voltage, an intrinsic discharge efficiency around 56% was predicted by simulation, and more than 60 lm W -1 lamp efficacy (for radiation converted into visible green light by phosphor coating) was demonstrated experimentally

  3. Designing a highly sensitive Eddy current sensor for evaluating damage on thermal barrier coating

    Kim, Jong Min; Kim, Hak Joon; Song, Sung Jin; Seok, Chang Seong; Lee, Yeong Ze [Dept. of Mechanical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Lee, Seul Gi [LG Electronics, Seoul (Korea, Republic of)

    2016-06-15

    A thermal barrier coating (TBC) has been widely applied to machine components working under high temperature as a thermal insulator owing to its critical financial and safety benefits to the industry. However, the nondestructive evaluation of TBC damage is not easy since sensing of the microscopic change that occurs on the TBC is required during an evaluation. We designed an eddy current probe for evaluating damage on a TBC based on the finite element method (FEM) and validated its performance through an experiment. An FEM analysis predicted the sensitivity of the probe, showing that impedance change increases as the TBC thermally degrades. In addition, the effect of the magnetic shield concentrating magnetic flux density was also observed. Finally, experimental validation showed good agreement with the simulation result.

  4. Millimeter Wave Hybrid Photonic Wireless Links for High-Speed Wireless Access and Mobile Fronthaul

    Rommel, Simon

    As the introduction of the fifth generation of mobile services (5G) is set to revolutionize the way people, devices and machines connect, the changes to the underlying networks and technologies are no less drastic. The massive increase in user and data capacity, as well as the decrease in latency...... networks. In summary, the work presented in this thesis has regarded a multitude of aspects of millimeter wave hybrid photonic wireless links, expanding upon the state of the art and showing their feasibility for use in fifth generation mobile and high speed wireless access networks – hopefully bringing...

  5. Dithiopheneindenofluorene (TIF) Semiconducting Polymers with Very High Mobility in Field-Effect Transistors

    Chen, Hu

    2017-07-19

    The charge-carrier mobility of organic semiconducting polymers is known to be enhanced when the energetic disorder of the polymer is minimized. Fused, planar aromatic ring structures contribute to reducing the polymer conformational disorder, as demonstrated by polymers containing the indacenodithiophene (IDT) repeat unit, which have both a low Urbach energy and a high mobility in thin-film-transistor (TFT) devices. Expanding on this design motif, copolymers containing the dithiopheneindenofluorene repeat unit are synthesized, which extends the fused aromatic structure with two additional phenyl rings, further rigidifying the polymer backbone. A range of copolymers are prepared and their electrical properties and thin-film morphology evaluated, with the co-benzothiadiazole polymer having a twofold increase in hole mobility when compared to the IDT analog, reaching values of almost 3 cm2 V−1 s−1 in bottom-gate top-contact organic field-effect transistors.

  6. Task Phase Recognition for Highly Mobile Workers in Large Building Complexes

    Stisen, Allan; Mathisen, Andreas; Krogh, Søren

    2016-01-01

    requirements on the accuracy of the indoor positioning, and thus come with low deployment and maintenance effort in real-world settings. We evaluated the proposed methods in a large hospital complex, where the highly mobile workers were recruited among the non-clinical workforce. The evaluation is based......-scale indoor work environments, namely from a WiFi infrastructure providing coarse grained indoor positioning, from inertial sensors in the workers’ mobile phones, and from a task management system yielding information about the scheduled tasks’ start and end locations. The methods presented have low...... on manually labelled real-world data collected over 4 days of regular work life of the mobile workforce. The collected data yields 83 tasks in total involving 8 different orderlies from a major university hospital with a building area of 160, 000 m2. The results show that the proposed methods can distinguish...

  7. Investigating the Mobility of Light Autonomous Tracked Vehicles using a High Performance Computing Simulation Capability

    Negrut, Dan; Mazhar, Hammad; Melanz, Daniel; Lamb, David; Jayakumar, Paramsothy; Letherwood, Michael; Jain, Abhinandan; Quadrelli, Marco

    2012-01-01

    This paper is concerned with the physics-based simulation of light tracked vehicles operating on rough deformable terrain. The focus is on small autonomous vehicles, which weigh less than 100 lb and move on deformable and rough terrain that is feature rich and no longer representable using a continuum approach. A scenario of interest is, for instance, the simulation of a reconnaissance mission for a high mobility lightweight robot where objects such as a boulder or a ditch that could otherwise be considered small for a truck or tank, become major obstacles that can impede the mobility of the light autonomous vehicle and negatively impact the success of its mission. Analyzing and gauging the mobility and performance of these light vehicles is accomplished through a modeling and simulation capability called Chrono::Engine. Chrono::Engine relies on parallel execution on Graphics Processing Unit (GPU) cards.

  8. Transparent, high mobility InGaZnO thin films deposited by PLD

    Suresh, Arun; Gollakota, Praveen; Wellenius, Patrick; Dhawan, Anuj; Muth, John F.

    2008-01-01

    Transparent oxide semiconductor, InGaZnO, thin films were prepared by pulsed laser deposition at room temperature. The carrier concentration was found to vary by several orders of magnitude from insulating to 10 19 carriers/cm 3 depending on the oxygen partial pressure during deposition. Hall mobilities as high as 16 cm 2 /V s were observed. This is approximately an order of magnitude higher than the mobility of amorphous silicon and indicates that InGaO 3 (ZnO) x with x ≤ 5 may be suitable for transparent, thin film transistor applications. Post-deposition annealing was found to strongly influence the carrier concentration while annealing effects on the electron mobility was less influential

  9. Mobility Performance in Slow- and High-Speed LTE Real Scenarios

    Gimenez, Lucas Chavarria; Cascino, Maria Carmela; Stefan, Maria

    2016-01-01

    Mobility performance and handover data interruption times in real scenarios are studied by means of field measurements in an operational LTE network. Both slow- and high-speed scenarios are analyzed by collecting results from two different areas: Aalborg downtown and the highway which encircles...... in the city center as cells on the same site often cover different non-crossing street canyons. Moreover, no handover failures are experienced in the measurements which confirms robust LTE mobility performance. The average interruption time, which is at least equal to the handover execution time, lays within...... the same city. Measurements reveal that the terminal is configured by the network with different handover parametrization depending on the serving cell, which indicates the use of mobility robustness optimization. Although the network is dominated by three sector sites, no intra-site handovers are observed...

  10. ¿Y ahora qué? Anticipated immigration status barriers and Latina/o high school students' future expectations.

    McWhirter, Ellen Hawley; Ramos, Karina; Medina, Cynthia

    2013-07-01

    Latina/o high school students without documentation face a challenging situation when they graduate from high school, with pathways to work and postsecondary education stymied by their immigration status. We examined the effects of anticipated barriers associated with immigration status, age, and sex on the dependent variables of vocational outcome expectations, anticipated external and internal barriers, and postsecondary schooling plans in a sample of 475 Latina/o high school students. Findings include that students anticipating immigration status problems had lower vocational outcome expectations and anticipated more external barriers to pursuing their postsecondary plans. Latina girls and older high school students anticipating immigration status problems were more likely to plan to attend 2-year rather than 4-year colleges, and less likely to plan on postsecondary education, respectively. Implications for practice, policy, and research are discussed. PsycINFO Database Record (c) 2013 APA, all rights reserved.

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

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

    2015-02-01

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

  12. Mobile Exercise Apps and Increased Leisure Time Exercise Activity: A Moderated Mediation Analysis of the Role of Self-Efficacy and Barriers

    Rosen, Zohn; Spierer, David; Weinberger-Litman, Sarah; Goldschein, Akiva; Robinson, Jonathan

    2015-01-01

    Background There are currently over 1000 exercise apps for mobile devices on the market. These apps employ a range of features, from tracking exercise activity to providing motivational messages. However, virtually nothing is known about whether exercise apps improve exercise levels and health outcomes and, if so, the mechanisms of these effects. Objective Our aim was to examine whether the use of exercise apps is associated with increased levels of exercise and improved health outcomes. We also develop a framework within which to understand how exercise apps may affect health and test multiple models of possible mechanisms of action and boundary conditions of these relationships. Within this framework, app use may increase physical activity by influencing variables such as self-efficacy and may help to overcome exercise barriers, leading to improved health outcomes such as lower body mass index (BMI). Methods In this study, 726 participants with one of three backgrounds were surveyed about their use of exercise apps and health: (1) those who never used exercise apps, (2) those who used exercise apps but discontinued use, and (3) those who are currently using exercise apps. Participants were asked about their long-term levels of exercise and about their levels of exercise during the previous week with the International Physical Activity Questionnaire (IPAQ). Results Nearly three-quarters of current app users reported being more active compared to under half of non-users and past users. The IPAQ showed that current users had higher total leisure time metabolic equivalent of task (MET) expenditures (1169 METs), including walking and vigorous exercise, compared to those who stopped using their apps (612 METs) or who never used apps (577 METs). Importantly, physical activity levels in domains other than leisure time activity were similar across the groups. The results also showed that current users had lower BMI (25.16) than past users (26.8) and non-users (26.9) and

  13. Mobile Exercise Apps and Increased Leisure Time Exercise Activity: A Moderated Mediation Analysis of the Role of Self-Efficacy and Barriers.

    Litman, Leib; Rosen, Zohn; Spierer, David; Weinberger-Litman, Sarah; Goldschein, Akiva; Robinson, Jonathan

    2015-08-14

    There are currently over 1000 exercise apps for mobile devices on the market. These apps employ a range of features, from tracking exercise activity to providing motivational messages. However, virtually nothing is known about whether exercise apps improve exercise levels and health outcomes and, if so, the mechanisms of these effects. Our aim was to examine whether the use of exercise apps is associated with increased levels of exercise and improved health outcomes. We also develop a framework within which to understand how exercise apps may affect health and test multiple models of possible mechanisms of action and boundary conditions of these relationships. Within this framework, app use may increase physical activity by influencing variables such as self-efficacy and may help to overcome exercise barriers, leading to improved health outcomes such as lower body mass index (BMI). In this study, 726 participants with one of three backgrounds were surveyed about their use of exercise apps and health: (1) those who never used exercise apps, (2) those who used exercise apps but discontinued use, and (3) those who are currently using exercise apps. Participants were asked about their long-term levels of exercise and about their levels of exercise during the previous week with the International Physical Activity Questionnaire (IPAQ). Nearly three-quarters of current app users reported being more active compared to under half of non-users and past users. The IPAQ showed that current users had higher total leisure time metabolic equivalent of task (MET) expenditures (1169 METs), including walking and vigorous exercise, compared to those who stopped using their apps (612 METs) or who never used apps (577 METs). Importantly, physical activity levels in domains other than leisure time activity were similar across the groups. The results also showed that current users had lower BMI (25.16) than past users (26.8) and non-users (26.9) and that this association was mediated by

  14. Mobilities Mobilities

    César Pompeyo

    2011-12-01

    Full Text Available Urry, John (2007 Mobilities.Oxford: Polity Press.Urry, John (2007 Mobilities.Oxford: Polity Press.John Urry (1946-, profesor en la Universidad de Lancaster, es un sociólogo de sobra conocido y altamente reputado en el panorama internacional de las ciencias sociales. Su dilatada carrera, aparentemente dispersa y diversificada, ha seguido senderos bastante bien definidos dejando tras de sí un catálogo extenso de obras sociológicas de primer nivel. Sus primeros trabajos se centraban en el campo de la teoría social y la filosofía de las ciencias sociales o de la sociología del poder [...

  15. High performance and transparent multilayer MoS2 transistors: Tuning Schottky barrier characteristics

    Young Ki Hong

    2016-05-01

    Full Text Available Various strategies and mechanisms have been suggested for investigating a Schottky contact behavior in molybdenum disulfide (MoS2 thin-film transistor (TFT, which are still in much debate and controversy. As one of promising breakthrough for transparent electronics with a high device performance, we have realized MoS2 TFTs with source/drain electrodes consisting of transparent bi-layers of a conducting oxide over a thin film of low work function metal. Intercalation of a low work function metal layer, such as aluminum, between MoS2 and transparent source/drain electrodes makes it possible to optimize the Schottky contact characteristics, resulting in about 24-fold and 3 orders of magnitude enhancement of the field-effect mobility and on-off current ratio, respectively, as well as transmittance of 87.4 % in the visible wavelength range.

  16. High performance and transparent multilayer MoS{sub 2} transistors: Tuning Schottky barrier characteristics

    Hong, Young Ki; Kwon, Junyeon; Hong, Seongin; Song, Won Geun; Liu, Na; Omkaram, Inturu; Kim, Sunkook, E-mail: kimskcnt@gmail.com, E-mail: ohms@keti.re.kr [Multi-Functional Bio/Nano Lab., Kyung Hee University, Gyeonggi 446-701 (Korea, Republic of); Yoo, Geonwook; Yoo, Byungwook; Oh, Min Suk, E-mail: kimskcnt@gmail.com, E-mail: ohms@keti.re.kr [Display Convergence Research Center, Korea Electronics Technology Institute, Gyeonggi 463-816 (Korea, Republic of); Ju, Sanghyun [Department of Physics, Kyonggi University, Suwon, Gyeonggi-Do 443-760 (Korea, Republic of)

    2016-05-15

    Various strategies and mechanisms have been suggested for investigating a Schottky contact behavior in molybdenum disulfide (MoS{sub 2}) thin-film transistor (TFT), which are still in much debate and controversy. As one of promising breakthrough for transparent electronics with a high device performance, we have realized MoS{sub 2} TFTs with source/drain electrodes consisting of transparent bi-layers of a conducting oxide over a thin film of low work function metal. Intercalation of a low work function metal layer, such as aluminum, between MoS{sub 2} and transparent source/drain electrodes makes it possible to optimize the Schottky contact characteristics, resulting in about 24-fold and 3 orders of magnitude enhancement of the field-effect mobility and on-off current ratio, respectively, as well as transmittance of 87.4 % in the visible wavelength range.

  17. Low Li+ Insertion Barrier Carbon for High Energy Efficient Lithium-Ion Capacitor.

    Lee, Wee Siang Vincent; Huang, Xiaolei; Tan, Teck Leong; Xue, Jun Min

    2018-01-17

    Lithium-ion capacitor (LIC) is an attractive energy-storage device (ESD) that promises high energy density at moderate power density. However, the key challenge in its design is the low energy efficient negative electrode, which barred the realization of such research system in fulfilling the current ESD technological inadequacy due to its poor overall energy efficiency. Large voltage hysteresis is the main issue behind high energy density alloying/conversion-type materials, which reduces the electrode energy efficiency. Insertion-type material though averted in most research due to the low capacity remains to be highly favorable in commercial application due to its lower voltage hysteresis. To further reduce voltage hysteresis and increase capacity, amorphous carbon with wider interlayer spacing has been demonstrated in the simulation result to significantly reduce Li + insertion barrier. Hence, by employing such amorphous carbon, together with disordered carbon positive electrode, a high energy efficient LIC with round-trip energy efficiency of 84.3% with a maximum energy density of 133 Wh kg -1 at low power density of 210 W kg -1 can be achieved.

  18. Development of internal transport barrier scenarios at ITER-relevant high triangularity in JET

    Rimini, F.G.; Becoulet, M.; Giovannozzi, E.; Lomas, P.J.; Tudisco, O.; Alper, B.; Crisanti, F.; Baar, M. de; Luna, E. de La; Vries, P. de; Ekedahl, A.; Hawkes, N.; Huysmans, G.; Litaudon, X.; Parail, V.; Saibene, G.; Tuccillo, A.A.; Zastrow, K.D.

    2005-01-01

    The development of scenarios characterized by H-mode confinement and internal transport barriers (ITBs) in high triangularity, δ ∼ 0.4-0.5, discharges is of particular interest for ITER advanced tokamak operation. Previous JET experiments have shown that high triangularity favours H-modes which are ELM-free or develop type I edge localized mode (ELM) activity, which inhibits long lasting ITBs. The recent experiments reported here concentrate on integrated optimization of edge and core conditions. The stability of the edge pedestal was controlled using gas injection, deuterium or light impurities, and plasma current ramps. Both methods yield more ITB-friendly edge pedestal conditions, varying from small type I to type III ELMs and, in extreme cases, resulting in L-mode. In parallel, the conditions for triggering and sustaining ITBs encompassing a large proportion of the plasma volume (outer ITBs) were optimized, as opposed to less performing ITBs located closer to the plasma centre (inner ITB). These plasmas have deeply reversed target current profiles with q min ∼ 3 and a narrow inner ITB, located typically at a small normalized radius ρ E , at q 95 = 7.5, H 89 β N ∼ 3.5-4 and ∼60% of the Greenwald density limit. In summary, a high triangularity scenario has been developed, which combines the desirable characteristics of controlled edge, long lasting wide ITBs and high performance at density higher than the low triangularity JET scenarios

  19. Barriers and opportunities for labels for highly energy-efficient houses

    Mlecnik, Erwin; Visscher, Henk; Van Hal, Anke

    2010-01-01

    Promoting energy efficiency in the building sector is essential if the agreements of the Kyoto Protocol are to be honoured. Different initiatives for energy labelling of highly energy-efficient residential buildings have emerged throughout Europe as an essential method to stimulate market demand, to control grants or to ensure the quality of demonstration projects with excellent energy performance. The paper identifies the barriers and opportunities for the further diffusion of labels for highly energy-efficient houses. A model based on the theory of the diffusion of innovation is developed to analyse perceived attributes of existing European labels. The paper investigates the innovation characteristics of existing labels in Europe, with a focus on advanced countries. The question of compatibility with the development of the European Energy Performance of Buildings Directive (EPBD) is examined in detail. We found that the diffusion of emerging and already existing voluntary European labels for highly energy-efficient houses is needed. Their complexity can be lowered and relative advantage, trialability, observability, and compatibility can be increased. EPBD calculation procedures should be able to receive highly energy-efficient houses. In the framework of the recast of the EPBD, official recognition of existing voluntary labels is recommended. (author)

  20. Determination of the coherence length in high-mobility semiconductor-coupled Josephson weak links

    Kleinsasser, A.W.

    1991-01-01

    A Nb-InAs-Nb superconductor-semiconductor-superconductor weak link based on a high-mobility homoepitaxial n-InAs film was reported recently [Akazaki, Kawakami, and Nittu J. Appl. Phys. 66, 6121 (1989)]. Measurements of the electron concentration, effective mass, and mobility allowed the coherence length in the normal link to be calculated. The mobility was high enough that the dirty limit was not applicable in the temperature range (∼2--7 K) over which the device critical current was measured. The temperature dependence of the critical current could not be fit by the usual theoretical form, even though an expression for the coherence length was used that should be applicable in both the clean and dirty limits. In this paper is demonstrated an excellent fit to the data, obtained by using the magnitude of the coherence length as a fitting parameter and assuming the dirty limit temperature dependence. This implies a coherence length proportional to T -1/2 but far shorter than that calculated from the known material parameters. It is suggested that a different scaling length may apply in high-mobility devices

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

    Zhang, Panlong; Wang, Haibo; Yan, Donghang

    2017-09-01

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

  2. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    Warwick, C. N.; Venkateshvaran, D.; Sirringhaus, H.

    2015-09-01

    We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) and 2,9-didecyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (C10-DNTT). The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014)] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

  3. Accurate on-chip measurement of the Seebeck coefficient of high mobility small molecule organic semiconductors

    C. N. Warwick

    2015-09-01

    Full Text Available We present measurements of the Seebeck coefficient in two high mobility organic small molecules, 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT and 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT. The measurements are performed in a field effect transistor structure with high field effect mobilities of approximately 3 cm2/V s. This allows us to observe both the charge concentration and temperature dependence of the Seebeck coefficient. We find a strong logarithmic dependence upon charge concentration and a temperature dependence within the measurement uncertainty. Despite performing the measurements on highly polycrystalline evaporated films, we see an agreement in the Seebeck coefficient with modelled values from Shi et al. [Chem. Mater. 26, 2669 (2014] at high charge concentrations. We attribute deviations from the model at lower charge concentrations to charge trapping.

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

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

    2016-04-01

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

  5. Limiting scattering processes in high-mobility InSb quantum wells grown on GaSb buffer systems

    Lehner, Ch. A.; Tschirky, T.; Ihn, T.; Dietsche, W.; Keller, J.; Fält, S.; Wegscheider, W.

    2018-05-01

    We present molecular beam epitaxial grown single- and double-side δ -doped InAlSb/InSb quantum wells with varying distances down to 50 nm to the surface on GaSb metamorphic buffers. We analyze the surface morphology as well as the impact of the crystalline quality on the electron transport. Comparing growth on GaSb and GaAs substrates indicates that the structural integrity of our InSb quantum wells is solely determined by the growth conditions at the GaSb/InAlSb transition and the InAlSb barrier growth. The two-dimensional electron gas samples show high mobilities of up to 349 000 cm2/Vs at cryogenic temperatures and 58 000 cm2/Vs at room temperature. With the calculated Dingle ratio and a transport lifetime model, ionized impurities predominantly remote from the quantum well are identified as the dominant source of scattering events. The analysis of the well-pronounced Shubnikov-de Haas oscillations reveals a high spin-orbit coupling with an effective g -factor of -38.4 in our samples. Along with the smooth surfaces and long mean free paths demonstrated, our InSb quantum wells are increasingly competitive for nanoscale implementations of Majorana mode devices.

  6. Analysis of current instabilities of thin AlN/GaN/AlN double heterostructure high electron mobility transistors

    Zervos, Ch; Adikimenakis, A; Bairamis, A; Kostopoulos, A; Kayambaki, M; Tsagaraki, K; Konstantinidis, G; Georgakilas, A

    2016-01-01

    The current instabilities of high electron mobility transistors (HEMTs), based on thin double AlN/GaN/AlN heterostructures (∼0.5 μm total thickness), directly grown on sapphire substrates, have been analyzed and compared for different AlN top barrier thicknesses. The structures were capped by 1 nm GaN and non-passivated 1 μm gate-length devices were processed. Pulsed I–V measurements resulted in a maximum cold pulsed saturation current of 1.4 A mm −1 at a gate-source voltage of +3 V for 3.7 nm AlN thickness. The measured gate and drain lag for 500 ns pulse-width varied between 6%–12% and 10%–18%, respectively. Furthermore, a small increase in the threshold voltage was observed for all the devices, possibly due to the trapping of electrons under the gate contact. The off-state breakdown voltage of V br  = 70 V, for gate-drain spacing of 2 μm, was approximately double the value measured for a single AlN/GaN HEMT structure grown on a thick GaN buffer layer. The results suggest that the double AlN/GaN/AlN heterostructures may offer intrinsic advantages for the breakdown and current stability characteristics of high current HEMTs. (paper)

  7. New WC-Cu thermal barriers for fusion applications: High temperature mechanical behaviour

    Tejado, E.; Dias, M.; Correia, J. B.; Palacios, T.; Carvalho, P. A.; Alves, E.; Pastor, J. Y.

    2018-01-01

    The combination of tungsten carbide and copper as a thermal barrier could effectively reduce the thermal mismatch between tungsten and copper alloy, which are proposed as base armour and heat sink, respectively, in the divertor of future fusion reactors. Furthermore, since the optimum operating temperature windows for these divertor materials do not overlap, a compatible thermal barrier interlayer between them is required to guarantee a smooth thermal transition, which in addition may mitigate radiation damage. The aim of this work is to study the thermo-mechanical properties of WC-Cu cermets fabricated by hot pressing. Focus is placed on the temperature effect and composition dependence, as the volume fraction of copper varies from 25 to 50 and 75 vol%. To explore this behaviour, fracture experiments are performed within a temperature range from room temperature to 800 °C under vacuum. In addition, elastic modulus and thermal expansion coefficient are estimated from these tests. Results reveal a strong dependence of the performance on temperature and on the volume fraction of copper and, surprisingly, a slight percent of Cu (25 vol%) can effectively reduce the large difference in thermal expansion between tungsten and copper alloy, which is a critical point for in service applications. The thermal performance of these materials, together with their mechanical properties could indeed reduce the heat transfer from the PFM to the underlying element while supporting the high thermal stresses of the joint. Thus, the presence of these cermets could allow the reactor to operate above the ductile to brittle transition temperature of tungsten, without compromising the underlying materials.

  8. Infrared gas phase study on plasma-polymer interactions in high-current diffuse dielectric barrier discharge

    Liu, Y.; Welzel, S.; Starostin, S. A.; van de Sanden, M. C. M.; Engeln, R.; de Vries, H. W.

    2017-01-01

    A roll-to-roll high-current diffuse dielectric barrier discharge at atmospheric pressure was operated in air and Ar/N2/O2 gas mixtures. The exhaust gas from the discharge was studied using a high-resolution Fourier-transform infrared spectrometer in the range from 3000 to 750?cm-1 to unravel the

  9. Ultra-high carrier mobility InSb film by rapid thermal annealing on glass substrate

    Charith Jayanada Koswaththage

    2016-11-01

    Full Text Available InSb films were deposited on both mica and glass substrates using thermal evaporation and subjected to FA or RTA. Crystallinity, composition and electrical properties were investigated. High Hall electron mobility as high as 25,000 cm2/(Vs was obtained with the capped InSb film by keeping the In:Sb ratio after RTA at 520°C for 30 sec or more without adopting epitaxial growth on glass.

  10. A High Speed Mobile Communication System implementing Bicasting Architecture on the IP Layer

    Yamada, Kazuhiro

    2012-01-01

    Having a broadband connection on high speed rails is something that business travelers want most. Increasing number of passengers is requesting even higher access speeds. We are proposing the Media Convergence System as an ideal communication system for future high speed mobile entities. The Media Convergence System recognizes plural wireless communication media between the ground network and each train, and then traffic is load-balanced over active media which varies according to circumstanc...

  11. Mobile probes

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....

  12. On barrier performance of high compaction bentonite in facilities of disposing high level radioactive wastes in formation

    Ikeda, Hidefumi; Komada, Hiroya

    1989-01-01

    As for the method of disposing high level radioactive wastes generated in the reprocessing of spent fuel, at present formation disposal is regarded as most promising. The most important point in this formation disposal is to prevent the leak of radioactive nuclides within the disposal facilities into bedrocks and their move to the zone of human life. As the method of formation disposal, the canisters containing high level radioactive wastes are placed in the horizontal or vertical holes for disposal dug from horizontal tunnels which are several hundreds m underground, and the tunnels and disposal holes are filled again. For this filling material, the barrier performance to prevent and retard the leak of radioactive nuclides out of the disposal facilities is expected, and the characteristics of low water permeability, the adsorption of nuclides and long term stability are required. However, due to the decay heat of wastes just after the disposal, high temperature and drying condition arises, and this must be taken in consideration. The characteristics required for filling materials and the selection of the materials, the features and classification of bentonite, the properties of high compaction bentonite, and the move of water, heat and nuclides in high compaction bentonite are reported.(Kako, I.)

  13. EB-PVD process management for highly productive zirconia thermal barrier coating of turbine blades

    Reinhold, E.; Botzler, P.; Deus, C.

    1999-01-01

    Zirconia thermal barrier coatings are well used in the turbine manufacturing industry because they ensure extended lifetimes of turbine blades. Compared with other techniques, EB-PVD processes are best suited for the deposition on turbine blades with regard to the layer properties. Therefore EB-PVD coaters for turbine blades are becoming increasingly interesting. The coating costs per component are mainly dependent on a highly productive solution for the deposition task. Thus the EB-PVD process management has to be optimized in order to meet the productivity requirements of the manufacturers. This includes the requirement of high deposition rates, large deposition areas, long time stable production cycles as well as a matched duration of preheating, deposition and cooling down per charge. Modern EB-PVD solutions to be introduced allow deposition rates on blades up to 7 μm/min. The consequences for the technological process management and plant design concerning long time stable coating cycles with high productivity will be discussed. (orig.)

  14. Mobile Phone Ratiometric Imaging Enables Highly Sensitive Fluorescence Lateral Flow Immunoassays without External Optical Filters.

    Shah, Kamal G; Singh, Vidhi; Kauffman, Peter C; Abe, Koji; Yager, Paul

    2018-05-14

    Paper-based diagnostic tests based on the lateral flow immunoassay concept promise low-cost, point-of-care detection of infectious diseases, but such assays suffer from poor limits of detection. One factor that contributes to poor analytical performance is a reliance on low-contrast chromophoric optical labels such as gold nanoparticles. Previous attempts to improve the sensitivity of paper-based diagnostics include replacing chromophoric labels with enzymes, fluorophores, or phosphors at the expense of increased fluidic complexity or the need for device readers with costly optoelectronics. Several groups, including our own, have proposed mobile phones as suitable point-of-care readers due to their low cost, ease of use, and ubiquity. However, extant mobile phone fluorescence readers require costly optical filters and were typically validated with only one camera sensor module, which is inappropriate for potential point-of-care use. In response, we propose to couple low-cost ultraviolet light-emitting diodes with long Stokes-shift quantum dots to enable ratiometric mobile phone fluorescence measurements without optical filters. Ratiometric imaging with unmodified smartphone cameras improves the contrast and attenuates the impact of excitation intensity variability by 15×. Practical application was shown with a lateral flow immunoassay for influenza A with nucleoproteins spiked into simulated nasal matrix. Limits of detection of 1.5 and 2.6 fmol were attained on two mobile phones, which are comparable to a gel imager (1.9 fmol), 10× better than imaging gold nanoparticles on a scanner (18 fmol), and >2 orders of magnitude better than gold nanoparticle-labeled assays imaged with mobile phones. Use of the proposed filter-free mobile phone imaging scheme is a first step toward enabling a new generation of highly sensitive, point-of-care fluorescence assays.

  15. Random demographic household surveys in highly mobile pastoral communities in Chad.

    Weibel, Daniel; Béchir, Mahamat; Hattendorf, Jan; Bonfoh, Bassirou; Zinsstag, Jakob; Schelling, Esther

    2011-05-01

    Reliable demographic data is a central requirement for health planning and management, and for the implementation of adequate interventions. This study addresses the lack of demographic data on mobile pastoral communities in the Sahel. A total of 1081 Arab, Fulani and Gorane women and 2541 children (1336 boys and 1205 girls) were interviewed and registered by a biometric fingerprint scanner in five repeated random transect demographic and health surveys conducted from March 2007 to January 2008 in the Lake Chad region in Chad. Important determinants for the planning and implementation of household surveys among mobile pastoral communities include: environmental factors; availability of women for interviews; difficulties in defining "own" children; the need for information-education-communication campaigns; and informed consent of husbands in typically patriarchal societies. Due to their high mobility, only 5% (56/1081) of registered women were encountered twice. Therefore, it was not possible to establish a demographic and health cohort. Prospective demographic and health cohorts are the most accurate method to assess child mortality and other demographic indices. However, their feasibility in a highly mobile pastoral setting remains to be shown. Future interdisciplinary scientific efforts need to target innovative methods, tools and approaches to include marginalized communities in operational health and demographic surveillance systems.

  16. Experiences from Implementing a Mobile Multiplayer Real-Time Game for Wireless Networks with High Latency

    Alf Inge Wang

    2009-01-01

    Full Text Available This paper describes results and experiences from designing, implementing, and testing a multiplayer real-time game over mobile networks with high latency. The paper reports on network latency and bandwidth measurements from playing the game live over GPRS, EDGE, UMTS, and WLAN using the TCP and the UDP protocols. These measurements describe the practical constraints of various wireless networks and protocols when used for mobile multiplayer game purposes. Further, the paper reports on experiences from implementing various approaches to minimize issues related to high latency. Specifically, the paper focuses on a discussion about how much of the game should run locally on the client versus on the server to minimize the load on the mobile device and obtain sufficient consistency in the game. The game was designed to reveal all kinds of implementation issues of mobile network multiplayer games. The goal of the game is for a player to push other players around and into traps where they loose their lives. The game relies heavily on collision detection between the players and game objects. The paper presents experiences from experimenting with various approaches that can be used to handle such collisions, and highlights the advantages and disadvantages of the various approaches.

  17. Random demographic household surveys in highly mobile pastoral communities in Chad

    Béchir, Mahamat; Hattendorf, Jan; Bonfoh, Bassirou; Zinsstag, Jakob; Schelling, Esther

    2011-01-01

    Abstract Problem Reliable demographic data is a central requirement for health planning and management, and for the implementation of adequate interventions. This study addresses the lack of demographic data on mobile pastoral communities in the Sahel. Approach A total of 1081 Arab, Fulani and Gorane women and 2541 children (1336 boys and 1205 girls) were interviewed and registered by a biometric fingerprint scanner in five repeated random transect demographic and health surveys conducted from March 2007 to January 2008 in the Lake Chad region in Chad. Local setting Important determinants for the planning and implementation of household surveys among mobile pastoral communities include: environmental factors; availability of women for interviews; difficulties in defining “own” children; the need for information-education-communication campaigns; and informed consent of husbands in typically patriarchal societies. Relevant changes Due to their high mobility, only 5% (56/1081) of registered women were encountered twice. Therefore, it was not possible to establish a demographic and health cohort. Lessons learnt Prospective demographic and health cohorts are the most accurate method to assess child mortality and other demographic indices. However, their feasibility in a highly mobile pastoral setting remains to be shown. Future interdisciplinary scientific efforts need to target innovative methods, tools and approaches to include marginalized communities in operational health and demographic surveillance systems. PMID:21556307

  18. New GaN based HEMT with Si3N4 or un-doped region in the barrier for high power applications

    Razavi, S. M.; Tahmasb Pour, S.; Najari, P.

    2018-06-01

    New AlGaN/GaN high electron mobility transistors (HEMTs) that their barrier layers under the gate are divided into two regions horizontally are presented in this work. Upper region is Si3N4 (SI-HEMT) or un-doped AlGaN (UN-HEMT) and lower region is AlGaN with heavier doping compared to barrier layer. Upper region in SI-HEMT and UN-HEMT reduces peak electric field in the channel and then improves breakdown voltage considerably. Lower region increases electron density in the two dimensional electron gas (2-DEG) and enhances drain current significantly. For instance, saturated drain current in SI-HEMT is about 100% larger than that in the conventional one. Moreover, the maximum breakdown voltage in the proposed structures is 65 V. This value is about 30% larger than that in the conventional transistor (50 V). Also, suggested structure reduces short channel effect such as DIBL. The maximum gm is obtained in UN-HEMT and conventional devices. Proposed structures improve breakdown voltage and saturated drain current and then enhance maximum output power density. Maximum output power density in the new structures is about 150% higher than that in the conventional.

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

    Zhu, Jie-Jie; Ma, Xiao-Hua; Hou, Bin; Chen, Wei-Wei; Hao, Yue

    2014-01-01

    Trap states in Al 0.55 Ga 0.45 N/GaN Schottky-gate high-electron-mobility transistors (S-HEMTs) and Al 2 O 3 /Al 0.55 Ga 0.45 N/GaN metal-oxide-semiconductor HEMTs (MOS-HEMTs) were investigated with conductance method in this paper. Surface states with time constant of (0.09–0.12) μs were found in S-HEMTs, and electron tunneling rather than emission was deemed to be the dominant de-trapping mechanism due to the high electric field in high Al content barrier. The density of surface states evaluated in S-HEMTs was (1.02–4.67)×10 13 eV −1 ·cm −2 . Al 2 O 3 gate insulator slightly reduced the surface states, but introduced low density of new traps with time constant of (0.65–1.29) μs into MOS-HEMTs

  20. Stakeholder Perceptions of Barriers and Solutions to Significant Expansion of Postsecondary Enrollment Options for High School Students

    Carl Wozniak

    2013-02-01

    Full Text Available Post-secondary experiences for students still in high school have been promoted as a means to increase academic rigor and create a better-trained workforce. Yet little is known regarding supports needed to significantly increase such options. This study obtained input from 411 stakeholders in one Midwestern state, including 201 district superintendents, 181 high school principals, and 23 college dual enrollment officers regarding their use of these options, their perceptions of barriers to program expansion, and their ranking of possible solutions to overcome the barriers. Findings demonstrate that all parties find postsecondary options of value, with traditional dual enrollment the most used option. Although all groups identified funding as a primary barrier, other systemic barriers were of great concern. Participants suggest that expansion of Advanced Placement and early and middle college programs, financial assistance for dually enrolled students, and increased program availability for career and technical options would be beneficial.Wozniak, Carl, (2012. Stakeholder Perceptions of Barriers and Solutions to Significant Expansion of Postsecondary Enrollment Options for High School Students. 8(2. Retrieved from www.ijepl.org .

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

    Du, Juan; Xia, Congxin; Liu, Yaming; Li, Xueping; Peng, Yuting; Wei, Shuyi

    2017-01-01

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

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

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

    2017-04-15

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

  3. Development of internal transport barrier scenarios at ITER-relevant high triangularity in Jet

    Rimini, F.G.; Becoulet, M.; Ekedahl, A.; Huysmans, G.; Joffrin, E.; Litaudon, X. [Association Euratom-CEA, Centre d' Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee; Giovannozzi, E.; Tudisco, O.; Crisanti, F. [Association Euratol/ENEA/CNR sulla Fusione, Frascali, Rome (Italy); Lomas, P.J.; Alper, B.; Hawkes, N.; Parail, V.; Zastrow, K.D. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Baar, M. de; Vries, P. de [Association Euratom-Fom, TEC Cluster, Nieuwegein (Netherlands); La Luna, E. de [Association Euratom-Ciemat, Madrid (Spain); Saibene, G. [EFDA CSU, Garching (Germany)

    2004-07-01

    The development of ITB s(Internal Transport Barrier) scenarios in high triangularity discharges is of particular interest for ITER advanced tokamak operation. Previous JET experiments have shown that high triangularity favours ELM (Edge Localized Mode)-Free or type I ELMs, which inhibit long lasting ITBs. The recent experiments reported here concentrate on integrated optimisation of edge and core conditions. Edge pedestal was controlled using gas injection, Deuterium or light impurities, and plasma current ramps. Both methods yield more ITB-friendly edge pedestal conditions, varying from small type I to type III ELMs and, in extreme cases, to L-mode edge. In parallel, the conditions for triggering and sustaining a wide ITB were optimised. This plasmas have deeply reversed target current profiles with g{sub min} 3. A narrow inner ITB, located in the reversed shear region, is routinely observed. Large radius ITBs are only triggered when the input power exceeds 20-22 MW, but they do not usually survive the transition into H-mode. The best results, in terms of sustained high performance, have been obtained with Neon injection: a wide ITB is triggered during the phase with L-mode edge and survives into H-mode for about 2 s at H{sub 89}{beta}{sub N} {approx} 3.5 and {approx} 60% of the Greenwald density limit. In summary, a high triangularity scenario has been developed, which combines the desirable I characteristics of controlled edge, long lasting wide ITBs and high performance at density higher than the low triangularity JET scenarios. (authors)

  4. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  5. Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

    Williamson, James M.; Trump, Darryl D.; Bletzinger, Peter; Ganguly, Biswa N.

    2006-10-01

    A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s-1. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ~3 × 1015 cm-3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ~8.5 × 1015 cm-3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level.

  6. Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

    Williamson, James M [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Trump, Darryl D [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Bletzinger, Peter [Innovative Scientific Solutions, Inc., 2766 Indian Ripple Road, Dayton, Ohio 45440-3638 (United States); Ganguly, Biswa N [Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433-7919 (United States)

    2006-10-21

    A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s{sup -1}. The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of {approx}3 x 10{sup 15} cm{sup -3} at 25 W. The maximum ozone production achieved by short-pulse excitation was {approx}8.5 x 10{sup 15} cm{sup -3} at 20 W, which was four times greater than that achieved by ac excitation at the same power level.

  7. Facile synthesis of high strength hot-water wood extract films with oxygen-barrier performance

    Chen, Ge-Gu; Fu, Gen-Que; Wang, Xiao-Jun; Gong, Xiao-Dong; Niu, Ya-Shuai; Peng, Feng; Yao, Chun-Li; Sun, Run-Cang

    2017-01-01

    Biobased nanocomposite films for food packaging with high mechanical strength and good oxygen-barrier performance were developed using a hot-water wood extract (HWE). In this work, a facile approach to produce HWE/montmorillonite (MMT) based nanocomposite films with excellent physical properties is described. The focus of this study was to determine the effects of the MMT content on the structure and mechanical properties of nanocomposites and the effects of carboxymethyl cellulose (CMC) on the physical properties of the HWE-MMT films. The experimental results suggested that the intercalation of HWE and CMC in montmorillonite could produce compact, robust films with a nacre-like structure and multifunctional characteristics. This results of this study showed that the mechanical properties of the film designated FCMC0.05 (91.5 MPa) were dramatically enhanced because the proportion of HWE, MMT and CMC was 1:1.5:0.05. In addition, the optimized films exhibited an oxygen permeability below 2.0 cm3 μm/day·m2·kPa, as well as good thermal stability due to the small amount of CMC. These results provide a comprehensive understanding for further development of high-performance nanocomposites which are based on natural polymers (HWE) and assembled layered clays (MMT). These films offer great potential in the field of sustainable packaging.

  8. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  9. Comparison of high-voltage ac and pulsed operation of a surface dielectric barrier discharge

    Williamson, James M; Trump, Darryl D; Bletzinger, Peter; Ganguly, Biswa N

    2006-01-01

    A surface dielectric barrier discharge (DBD) in atmospheric pressure air was excited either by low frequency (0.3-2 kHz) high-voltage ac or by short, high-voltage pulses at repetition rates from 50 to 600 pulses s -1 . The short-pulse excited discharge was more diffuse and did not have the pronounced bright multiple cathode spots observed in the ac excited discharge. The discharge voltage, current and average power deposited into the discharge were calculated for both types of excitation. As a measure of plasma-chemical efficiency, the ozone number density was measured by UV absorption as a function of average deposited power. The density of ozone produced by ac excitation did not increase so rapidly as that produced by short-pulse excitation as a function of average power, with a maximum measured density of ∼3 x 10 15 cm -3 at 25 W. The maximum ozone production achieved by short-pulse excitation was ∼8.5 x 10 15 cm -3 at 20 W, which was four times greater than that achieved by ac excitation at the same power level

  10. Comparison of fixed-bearing and mobile-bearing total knee arthroplasty after high tibial osteotomy.

    Hernigou, Philippe; Huys, Maxime; Pariat, Jacques; Roubineau, François; Flouzat Lachaniette, Charles Henri; Dubory, Arnaud

    2018-02-01

    There is no information comparing the results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in the same patients previously treated by high tibial osteotomy. The purpose was therefore to compare fixed-bearing and mobile-bearing total knee replacements in patients treated with previous high tibial osteotomy. We compared the results of 57 patients with osteoarthritis who had received a fixed-bearing prosthesis after high tibial osteotomy with the results of 41 matched patients who had received a rotating platform after high tibial osteotomy. The match was made for length of follow-up period. The mean follow-up was 17 years (range, 15-20 years). The patients were assessed clinically and radiographically. The pre-operative knee scores had no statistically significant differences between the two groups. So was the case with the intra-operative releases, blood loss, thromboembolic complications and infection rates in either group. There was significant improvement in both groups of knees, and no significant difference was observed between the groups (i.e., fixed-bearing and mobile-bearing knees) for the mean Knee Society knee clinical score (95 and 92 points, respectively), or the Knee Society knee functional score (82 and 83 points, respectively) at the latest follow-up. However, the mean post-operative knee motion was higher for the fixed-bearing group (117° versus 110°). In the fixed-bearing group, one knee was revised because of periprosthetic fracture. In the rotating platform mobile-bearing group, one knee was revised because of aseptic loosening of the tibial component. The Kaplan-Meier survivorship for revision at ten years of follow-up was 95.2% for the fixed bearing prosthesis and 91.1% for the rotating platform mobile-bearing prosthesis. Although we did manage to detect significant differences mainly in clinical and radiographic results between the two groups, we found no superiority or inferiority of the mobile

  11. AlGaN/GaN high-electron-mobility transistors with transparent gates by Al-doped ZnO

    Wang Chong; He Yun-Long; Zheng Xue-Feng; Ma Xiao-Hua; Zhang Jin-Cheng; Hao Yue

    2013-01-01

    AlGaN/GaN high-electron-mobility transistors (HEMTs) with Al-doped ZnO (AZO) transparent gate electrodes are fabricated, and Ni/Au/Ni-gated HEMTs are produced in comparison. The AZO-gated HEMTs show good DC characteristics and Schottky rectifying characteristics, and the gate electrodes achieve excellent transparencies. Compared with Ni/Au/Ni-gated HEMTs, AZO-gated HEMTs show a low saturation current, high threshold voltage, high Schottky barrier height, and low gate reverse leakage current. Due to the higher gate resistivity, AZO-gated HEMTs exhibit a current—gain cutoff frequency (f T ) of 10 GHz and a power gain cutoff frequency (f max ) of 5 GHz, and lower maximum oscillation frequency than Ni/Au/Ni-gated HEMTs. Moreover, the C—V characteristics are measured and the gate interface characteristics of the AZO-gated devices are investigated by a C—V dual sweep

  12. High-electric-field-stress-induced degradation of SiN passivated AlGaN/GaN high electron mobility transistors

    Wen-Ping, Gu; Huan-Tao, Duan; Jin-Yu, Ni; Yue, Hao; Jin-Cheng, Zhang; Qian, Feng; Xiao-Hua, Ma

    2009-01-01

    AlGaN/GaN high electron mobility transistors (HEMTs) are fabricated by employing SiN passivation, this paper investigates the degradation due to the high-electric-field stress. After the stress, a recoverable degradation has been found, consisting of the decrease of saturation drain current I Dsat , maximal transconductance g m , and the positive shift of threshold voltage V TH at high drain-source voltage V DS . The high-electric-field stress degrades the electric characteristics of AlGaN/GaN HEMTs because the high field increases the electron trapping at the surface and in AlGaN barrier layer. The SiN passivation of AlGaN/GaN HEMTs decreases the surface trapping and 2DEG depletion a little during the high-electric-field stress. After the hot carrier stress with V DS = 20 V and V GS = 0 V applied to the device for 10 4 sec, the SiN passivation decreases the stress-induced degradation of I Dsat from 36% to 30%. Both on-state and pulse-state stresses produce comparative decrease of I Dsat , which shows that although the passivation is effective in suppressing electron trapping in surface states, it does not protect the device from high-electric-field degradation in nature. So passivation in conjunction with other technological solutions like cap layer, prepassivation surface treatments, or field-plate gate to weaken high-electric-field degradation should be adopted. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. An analytic current-voltage model for quasi-ballistic III-nitride high electron mobility transistors

    Li, Kexin; Rakheja, Shaloo

    2018-05-01

    We present an analytic model to describe the DC current-voltage (I-V) relationship in scaled III-nitride high electron mobility transistors (HEMTs) in which transport within the channel is quasi-ballistic in nature. Following Landauer's transport theory and charge calculation based on two-dimensional electrostatics that incorporates negative momenta states from the drain terminal, an analytic expression for current as a function of terminal voltages is developed. The model interprets the non-linearity of access regions in non-self-aligned HEMTs. Effects of Joule heating with temperature-dependent thermal conductivity are incorporated in the model in a self-consistent manner. With a total of 26 input parameters, the analytic model offers reduced empiricism compared to existing GaN HEMT models. To verify the model, experimental I-V data of InAlN/GaN with InGaN back-barrier HEMTs with channel lengths of 42 and 105 nm are considered. Additionally, the model is validated against numerical I-V data obtained from DC hydrodynamic simulations of an unintentionally doped AlGaN-on-GaN HEMT with 50-nm gate length. The model is also verified against pulsed I-V measurements of a 150-nm T-gate GaN HEMT. Excellent agreement between the model and experimental and numerical results for output current, transconductance, and output conductance is demonstrated over a broad range of bias and temperature conditions.

  14. Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results

    Li, X.; Nilsson, D.; Danielsson, Ö.; Pedersen, H.; Janzén, E.; Forsberg, U. [Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping 58183 (Sweden); Bergsten, J.; Rorsman, N. [Microwave Electronics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, Göteborg 41296 (Sweden)

    2015-12-28

    The creation of a semi insulating (SI) buffer layer in AlGaN/GaN High Electron Mobility Transistor (HEMT) devices is crucial for preventing a current path beneath the two-dimensional electron gas (2DEG). In this investigation, we evaluate the use of a gaseous carbon gas precursor, propane, for creating a SI GaN buffer layer in a HEMT structure. The carbon doped profile, using propane gas, is a two stepped profile with a high carbon doping (1.5 × 10{sup 18 }cm{sup −3}) epitaxial layer closest to the substrate and a lower doped layer (3 × 10{sup 16 }cm{sup −3}) closest to the 2DEG channel. Secondary Ion Mass Spectrometry measurement shows a uniform incorporation versus depth, and no memory effect from carbon doping can be seen. The high carbon doping (1.5 × 10{sup 18 }cm{sup −3}) does not influence the surface morphology, and a roughness root-mean-square value of 0.43 nm is obtained from Atomic Force Microscopy. High resolution X-ray diffraction measurements show very sharp peaks and no structural degradation can be seen related to the heavy carbon doped layer. HEMTs are fabricated and show an extremely low drain induced barrier lowering value of 0.1 mV/V, demonstrating an excellent buffer isolation. The carbon doped GaN buffer layer using propane gas is compared to samples using carbon from the trimethylgallium molecule, showing equally low leakage currents, demonstrating the capability of growing highly resistive buffer layers using a gaseous carbon source.

  15. Very high channel conductivity in low-defect AlN/GaN high electron mobility transistor structures

    Dabiran, A. M.; Wowchak, A. M.; Osinsky, A.; Xie, J.; Hertog, B.; Cui, B.; Chow, P. P.; Look, D. C.

    2008-01-01

    Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm 2 /V s) and sheet charge density (>3x10 13 cm -2 ), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼100 Ω/□ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼1.3 A/mm and a peak transconductance of ∼260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented

  16. Mobile plant for encapsulating of solid high-level radioactive waste in metal matrix

    Sobolev, I.A.; Arustamov, A.Eh.; Shiryaev, V.V.; Ozhovan, M.I.; Semenov, K.N.; Kachalov, M.B.

    1993-01-01

    Technology for disposal of spent radionuclide sources of ionizing radiation into the standard well-type storage facilities is considered. Universal mobile facility, providing for incorporation of high-level solid wastes into metallic matrices, is proposed. The facility consists of separate moduli, assembled on a transport platform. Electrical meter, wherein the matrix metal (lead and its alloys) is melted and heated up to 600-800 C constitutes the basic modulus in the facility. 4 refs., 4 figs

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

    2017-03-01

    non - ionizing proton radiation damage effects at different energy levels on a GaN-on-silicon high electron mobility transistor...DISTRIBUTION CODE 13. ABSTRACT (maximum 200 words) In this work, a physics-based simulation of non - ionizing proton radiation damage effects at different...Polarization . . . . . . . . . . . . . . 6 2.3 Non - Ionizing Radiation Damage Effects . . . . . . . . . . . . . . . 10 2.4 Non - Ionizing Radiation Damage in

  18. Growth parameter optimization and interface treatment for enhanced electron mobility in heavily strained GaInAs/AlInAs high electron mobility transistor structures

    Fedoryshyn, Yuriy; Ostinelli, Olivier; Alt, Andreas; Pallin, Angel; Bolognesi, Colombo R.

    2014-01-01

    The optimization of heavily strained Ga 0.25 In 0.75 As/Al 0.48 In 0.52 As high electron mobility transistor structures is discussed in detail. The growth parameters and the channel layer interfaces were optimized in order to maximize the mobility of the two-dimensional electron gas. Structures composed of an 11 nm thick channel layer and a 4 nm thick spacer layer exhibited electron mobilities as high as 15 100 cm 2 /Vs and 70 000 cm 2 /Vs at 300 and 77 K, respectively, for channels including InAs strained layers. The sheet carrier density was kept above 2.5 × 10 12  cm −2 throughout the entire study

  19. Tensile toughness test and high temperature fracture analysis of thermal barrier coatings

    Qian, G.; Nakamura, T.; Berndt, C.C.; Leigh, S.H.

    1997-01-01

    In this paper, an effective fracture toughness test which uses interface fracture mechanics theory is introduced. This method is ideally suited for determining fracture resistance of multilayered thermal barrier coatings (TBCs) consisting of ceramic and bond layers and, unlike other fracture experiments, requires minimal set-up over a simple tensile adhesion test. Furthermore, while other test methods usually use edge cracked specimens, the present test models a crack embedded within the coatings, which is more consistent with actual TBCs where failure initiates from internal voids or defects. The results of combined computational and experimental analysis show that any defects located within the ceramic coating can significantly weaken a TBC, whereas the debonding resistances of the bond coating and its interfaces are found to be much higher. In a separate analysis, the authors have studied fracture behavior of TBCs subjected to thermal loading in a high temperature environment. The computed fracture parameters reveal that when the embedded crack size is on order of the coating thickness, the fracture driving force is comparable to the fracture resistance of the coating found in the toughness test. In addition, the major driving force for fracture derives from the thermal insulating effect across the crack faces rather than the mismatch in the coefficients of thermal expansion. The authors have also investigated the effects of functionally graded material (FGM) within TBCs and found its influences on the fracture parameters to be small. This result implies that the FGM may not contribute toward enhancing the fracture toughness of the TBCs considered here

  20. Accelerated high fidelity prion amplification within and across prion species barriers.

    Kristi M Green

    2008-08-01

    Full Text Available Experimental obstacles have impeded our ability to study prion transmission within and, more particularly, between species. Here, we used cervid prion protein expressed in brain extracts of transgenic mice, referred to as Tg(CerPrP, as a substrate for in vitro generation of chronic wasting disease (CWD prions by protein misfolding cyclic amplification (PMCA. Characterization of this infectivity in Tg(CerPrP mice demonstrated that serial PMCA resulted in the high fidelity amplification of CWD prions with apparently unaltered properties. Using similar methods to amplify mouse RML prions and characterize the resulting novel cervid prions, we show that serial PMCA abrogated a transmission barrier that required several hundred days of adaptation and subsequent stabilization in Tg(CerPrP mice. While both approaches produced cervid prions with characteristics distinct from CWD, the subtly different properties of the resulting individual prion isolates indicated that adaptation of mouse RML prions generated multiple strains following inter-species transmission. Our studies demonstrate that combined transgenic mouse and PMCA approaches not only expedite intra- and inter-species prion transmission, but also provide a facile means of generating and characterizing novel prion strains.

  1. Role of high-temperature creep stress in thermally grown oxide growth of thermal barrier coatings

    Ogawa, K.; Nakao, Y.; Seo, D.; Miura, H.; Shoji, T. [Tohoku Univ., Sendai (Japan)

    2008-07-01

    Thermally grown oxide (TGO) grows at the top / bond coating interface of the thermal barrier coating (TBC) in service. It is supposed that the failures of the TBC occur due to thermal stress and the decrease of adhesive strength caused by the TGO growth. Recently, large local stress has been found to change both the diffusion constant of oxygen through an existing oxide and the rate of chemical reaction at the oxide / oxidized material interface. Since high thermal stress occurs in the TBC, the volume expansion of the newly grown oxide, and centrifugal force, the growth rate of the TGO may change depending on not only temperature but also the stress. The aim of this study is to make clear the influence of stress on the growth rate of the TGO quantitatively. As a result, the thickness of the TGO clearly increases with increase of the amplitude of the applied stress and temperature. The increase rate of the TGO thickness is approximately 23% when the applied stress is increased from 0 to 205 MPa at 900 C, and approximately 29% when the stress is increased from 0 to 150 MPa at 950 C. (orig.)

  2. Pulse-height response of silicon surface-barrier detectors to high-energy heavy ions

    Smith, G.D.

    1973-01-01

    The pulse-height defect (PHD) of high-energy heavy ions in silicon surface-barrier detectors can be divided into three components: (1) energy loss in the gold-surface layer, (2) a nuclear-stopping defect, and (3) a defect due to recombination of electron-hole pairs in the plasma created by the heavy ion. The plasma recombination portion of the PHD was the subject of this study using the variation of the PHD with (1) the angle of incidence of incoming heavy ions, and (2) changes in the detector bias. The Tandem Van de Graaff accelerator at Argonne National Laboratory was used to produce scattered beam ions ( 32 S, 35 Cl) and heavy target recoils (Ni, Cu, 98 Mo, Ag, Au) at sufficient energies to produce a significant recombination defect. The results confirm the existence of a recombination zone at the front surface of these detectors and the significance of plasma recombination as a portion of the pulse-height defect. (Diss. Abstr. Int., B)

  3. Containment barrier metals for high-level waste packages in a Tuff repository

    Russell, E.W.; McCright, R.D.; O`Neal, W.C.

    1983-10-12

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Waste Package project is part of the US Department of Energy`s Civilian Radioactive Waste Management (CRWM) Program. The NNWSI project is working towards the development of multibarriered packages for the disposal of spent fuel and high-level waste in tuff in the unsaturated zone at Yucca Mountain at the Nevada Test Site (NTS). The final engineered barrier system design may be composed of a waste form, canister, overpack, borehole liner, packing, and the near field host rock, or some combination thereof. Lawrence Livermore National Laboratory`s (LLNL) role is to design, model, and test the waste package subsystem for the tuff repository. At the present stage of development of the nuclear waste management program at LLNL, the detailed requirements for the waste package design are not yet firmly established. In spite of these uncertainties as to the detailed package requirements, we have begun the conceptual design stage. By conceptual design, we mean design based on our best assessment of present and future regulatory requirements. We anticipate that changes will occur as the detailed requirements for waste package design are finalized. 17 references, 4 figures, 10 tables.

  4. Containment barrier metals for high-level waste packages in a Tuff repository

    Russell, E.W.; McCright, R.D.; O'Neal, W.C.

    1983-01-01

    The Nevada Nuclear Waste Storage Investigations (NNWSI) Waste Package project is part of the US Department of Energy's Civilian Radioactive Waste Management (CRWM) Program. The NNWSI project is working towards the development of multibarriered packages for the disposal of spent fuel and high-level waste in tuff in the unsaturated zone at Yucca Mountain at the Nevada Test Site (NTS). The final engineered barrier system design may be composed of a waste form, canister, overpack, borehole liner, packing, and the near field host rock, or some combination thereof. Lawrence Livermore National Laboratory's (LLNL) role is to design, model, and test the waste package subsystem for the tuff repository. At the present stage of development of the nuclear waste management program at LLNL, the detailed requirements for the waste package design are not yet firmly established. In spite of these uncertainties as to the detailed package requirements, we have begun the conceptual design stage. By conceptual design, we mean design based on our best assessment of present and future regulatory requirements. We anticipate that changes will occur as the detailed requirements for waste package design are finalized. 17 references, 4 figures, 10 tables

  5. Development of spraying methods for high density bentonite barriers. Part 3. Field investigation of spraying methods

    Tanaka, Toshiyuki; Nakajima, Makoto; Kobayashi, Ichizo; Toida, Masaru; Fukuda, Katsumi; Sato, Tatsuro; Nonaka, Katsumi; Gozu, Keisuke

    2007-01-01

    The authors have developed a new method of constructing high density bentonite barriers by means of a wet spraying method. Using this method, backfill material can be placed in narrow upper and side parts in a low-level radioactive waste disposal facility. Using a new supplying machine for bentonite, spraying tests were conducted to investigate the conditions during construction. On the basis of the test results, the various parameters for the spraying method were investigated. The test results are summarized as follows: 1. The new machine supplied about twice the weight of material supplied by a screw conveyor. A dry density of spraying bentonite 0.05 Mg/m 3 higher than that of a screw conveyor with the same water content could be achieved. 2. The dry density of sprayed bentonite at a boundary with concrete was the same as that at the center of the cross section. 3. The variation in densities of bentonite sprayed in the vertical downward and horizontal directions was small. Also, density reduction due to rebound during spraying was not seen. 4. Bentonite controlled by water content could be sprayed smoothly in the horizontal direction by a small machine. Also rebound could be collected by a machine conveying air. (author)

  6. High-temperature stability of yttria-stabilized zirconia thermal barrier ...

    temperature drop was found to increase with the coating thickness of YSZ. The coatings ... thermal barrier coating system on niobium alloys for supersonic vehicles. .... Voltage (V). 75 ..... However, distribution of the other elements; such as Ni,.

  7. Local imaging of high mobility two-dimensional electron systems with virtual scanning tunneling microscopy

    Pelliccione, M. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, University of California, Santa Barbara, Santa Barbara, California 93106 (United States); Bartel, J.; Goldhaber-Gordon, D. [Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305 (United States); Sciambi, A. [Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, California 94305 (United States); Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Pfeiffer, L. N.; West, K. W. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States)

    2014-11-03

    Correlated electron states in high mobility two-dimensional electron systems (2DESs), including charge density waves and microemulsion phases intermediate between a Fermi liquid and Wigner crystal, are predicted to exhibit complex local charge order. Existing experimental studies, however, have mainly probed these systems at micron to millimeter scales rather than directly mapping spatial organization. Scanning probes should be well-suited to study the spatial structure of these states, but high mobility 2DESs are found at buried semiconductor interfaces, beyond the reach of conventional scanning tunneling microscopy. Scanning techniques based on electrostatic coupling to the 2DES deliver important insights, but generally with resolution limited by the depth of the 2DES. In this letter, we present our progress in developing a technique called “virtual scanning tunneling microscopy” that allows local tunneling into a high mobility 2DES. Using a specially designed bilayer GaAs/AlGaAs heterostructure where the tunnel coupling between two separate 2DESs is tunable via electrostatic gating, combined with a scanning gate, we show that the local tunneling can be controlled with sub-250 nm resolution.

  8. Dietary differentiation and the evolution of population genetic structure in a highly mobile carnivore.

    Małgorzata Pilot

    Full Text Available Recent studies on highly mobile carnivores revealed cryptic population genetic structures correlated to transitions in habitat types and prey species composition. This led to the hypothesis that natal-habitat-biased dispersal may be responsible for generating population genetic structure. However, direct evidence for the concordant ecological and genetic differentiation between populations of highly mobile mammals is rare. To address this we analyzed stable isotope profiles (δ(13C and δ(15N values for Eastern European wolves (Canis lupus as a quantifiable proxy measure of diet for individuals that had been genotyped in an earlier study (showing cryptic genetic structure, to provide a quantitative assessment of the relationship between individual foraging behavior and genotype. We found a significant correlation between genetic distances and dietary differentiation (explaining 46% of the variation in both the marginal test and crucially, when geographic distance was accounted for as a co-variable. These results, interpreted in the context of other possible mechanisms such as allopatry and isolation by distance, reinforce earlier studies suggesting that diet and associated habitat choice are influencing the structuring of populations in highly mobile carnivores.

  9. High-mobility pyrene-based semiconductor for organic thin-film transistors.

    Cho, Hyunduck; Lee, Sunyoung; Cho, Nam Sung; Jabbour, Ghassan E; Kwak, Jeonghun; Hwang, Do-Hoon; Lee, Changhee

    2013-05-01

    Numerous conjugated oligoacenes and polythiophenes are being heavily studied in the search for high-mobility organic semiconductors. Although many researchers have designed fused aromatic compounds as organic semiconductors for organic thin-film transistors (OTFTs), pyrene-based organic semiconductors with high mobilities and on-off current ratios have not yet been reported. Here, we introduce a new pyrene-based p-type organic semiconductor showing liquid crystal behavior. The thin film characteristics of this material are investigated by varying the substrate temperature during the deposition and the gate dielectric condition using the surface modification with a self-assembled monolayer, and systematically studied in correlation with the performances of transistor devices with this compound. OTFT fabricated under the optimum deposition conditions of this compound, namely, 1,6-bis(5'-octyl-2,2'-bithiophen-5-yl)pyrene (BOBTP) shows a high-performance transistor behavior with a field-effect mobility of 2.1 cm(2) V(-1) s(-1) and an on-off current ratio of 7.6 × 10(6) and enhanced long-term stability compared to the pentacene thin-film transistor.

  10. Self-Efficacy, Perceptions of Barriers, Vocational Identity, and the Career Exploration Behavior of Latino/a High School Students

    Gushue, George V.; Clarke, Christine P.; Pantzer, Karen M.; Scanlan, Kolone R. L.

    2006-01-01

    This study explored the potential relationship between the social cognitive variables of career decision making self-efficacy and perceptions of barriers and the outcome variables of vocational identity and career exploration behaviors in a sample of 128 urban Latino/a high school students. The results indicated that higher levels of career…

  11. Motivators of and Barriers to Health-Promoting Behaviors among Culturally Diverse Middle and High School Students

    Wippold, Guillermo M.; Tucker, Carolyn M; Smith, Tasia M.; Rodriguez, Victoria A.; Hayes, Lynda F.; Folger, Austin C.

    2018-01-01

    Background: Youth obesity in the United States is a major health concern. Obesity can be reduced by increasing health-promoting behaviors. Purpose: The goals of the present study were to (1) identify the strongest motivators of and barriers to health-promoting behaviors among a culturally diverse group of middle and high school students and (2)…

  12. High School Teachers' Perspectives on Supporting Students with Visual Impairments toward Higher Education: Access, Barriers, and Success

    Reed, Maureen; Curtis, Kathryn

    2011-01-01

    The objective of the study presented here was to understand the experiences of teachers in assisting students with visual impairments in making the transition to higher education. The teachers reported barriers in high school that affect students' access to and success in higher education. Furthermore, institutions of higher education provided…

  13. Do Barriers to Crime Prevention Moderate the Effects of Situational Crime Prevention Policies on Violent Crime in High Schools?

    Sevigny, Eric L.; Zhang, Gary

    2018-01-01

    This study investigates how barriers to school-based crime prevention programming moderate the effects of situational crime prevention (SCP) policies on levels of violent crime in U.S. public high schools. Using data from the 2008 School Survey on Crime and Safety, we estimate a series of negative binomial regression models with interactions to…

  14. Barriers to Condom Use among High Risk Men Who Have Sex with Men in Uganda: A Qualitative Study.

    Geofrey Musinguzi

    Full Text Available Unprotected sexual intercourse is a major risk factor for HIV transmission. Men who have sex with men (MSM face challenges in accessing HIV prevention services, including condoms. However, there is limited in-depth assessment and documentation of the barriers to condom use among MSM in sub-Saharan Africa. In this paper, we examine the barriers to condom use among MSM in Uganda.The data for this study were extracted from a larger qualitative study conducted among 85 self-identified adult (>18 years MSM in 11 districts in Uganda between July and December 2013. Data on sexual behaviours and access and barriers to condom use were collected using semi-structured interviews. All interviews were audio-recorded and transcribed verbatim. This paper presents an analysis of data for 33 MSM who did not use condoms at last sex, with a focus on barriers to condom use. Analysis was conducted using the content analysis approach.Six major barriers to condom use were identified: Difficulties with using condoms, access challenges, lack of knowledge and misinformation about condom use, partner and relationship related issues, financial incentives and socio-economic vulnerability, and alcohol consumption.The findings suggest that several reasons account for lack of condom use among high-risk MSM. The findings are valuable to inform interventions needed to increase condom use among MSM.

  15. Barrier inhomogeneities and electronic transport of Pt contacts to relatively highly doped n-type 4H-SiC

    Huang, Lingqin; Wang, Dejun

    2015-01-01

    The barrier characteristics of Pt contacts to relatively highly doped (∼1 × 10 18  cm −3 ) 4H-SiC were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range of 160–573 K. The barrier height and ideally factor estimated from the I-V characteristics based on the thermionic emission model are abnormally temperature-dependent, which can be explained by assuming the presence of a double Gaussian distribution (GD) of inhomogeneous barrier heights. However, in the low temperature region (160–323 K), the obtained mean barrier height according to GD is lower than the actual mean value from C-V measurement. The values of barrier height determined from the thermionic field emission model are well consistent with those from the C-V measurements, which suggest that the current transport process could be modified by electron tunneling at low temperatures

  16. Development of highly flexible and ultra-low permeation rate thin-film barrier structure for organic electronics

    Kim, Namsu; Graham, Samuel

    2013-01-01

    A flexible thin-film encapsulation architecture for organic electronics was built and consisted of a silicon oxide/alumina and parylene layer deposited over Ca sensors on a barrier-coated polyethylene terephthalate substrate. The film's effective water vapor transmission rate was 2.4 ± 1.5 × 10 −5 g/m 2 /day at 20 °C and 50% relative humidity. Flexural tests revealed that for films deposited on the polyethylene terephthalate substrate, the barrier layer failed due to cracking at a curvature radius of 6.4 mm, corresponding to a strain of 0.8%. Adding an epoxy top coat of suitable thickness shifted the neutral axis toward the encapsulation layer, reducing the induced strain. Barrier performance was maintained under the 6.4 mm radius of curvature in this encapsulation structure. Thus, shifting the neutral axis via device structural design is an effective method of extending the flexibility of thin-film encapsulation structure without compromising the performance loss as a barrier layer. - Highlights: • High performance barrier is fabricated on flexible substrate. • The water vapor transmission rate is 2.4 ± 1.5 × 10 −5 g/m 2 /day. • The structure maintains its performance under a small radius of bending curvature

  17. Polymer/metal oxide hybrid dielectrics for low voltage field-effect transistors with solution-processed, high-mobility semiconductors

    Held, Martin; Schießl, Stefan P.; Gannott, Florentina [Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen D-91058 (Germany); Institute for Physical Chemistry, Universität Heidelberg, Heidelberg D-69120 (Germany); Miehler, Dominik [Department of Materials Science and Engineering, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen D-91058 (Germany); Zaumseil, Jana, E-mail: zaumseil@uni-heidelberg.de [Institute for Physical Chemistry, Universität Heidelberg, Heidelberg D-69120 (Germany)

    2015-08-24

    Transistors for future flexible organic light-emitting diode (OLED) display backplanes should operate at low voltages and be able to sustain high currents over long times without degradation. Hence, high capacitance dielectrics with low surface trap densities are required that are compatible with solution-processable high-mobility semiconductors. Here, we combine poly(methyl methacrylate) (PMMA) and atomic layer deposition hafnium oxide (HfO{sub x}) into a bilayer hybrid dielectric for field-effect transistors with a donor-acceptor polymer (DPPT-TT) or single-walled carbon nanotubes (SWNTs) as the semiconductor and demonstrate substantially improved device performances for both. The ultra-thin PMMA layer ensures a low density of trap states at the semiconductor-dielectric interface while the metal oxide layer provides high capacitance, low gate leakage and superior barrier properties. Transistors with these thin (≤70 nm), high capacitance (100–300 nF/cm{sup 2}) hybrid dielectrics enable low operating voltages (<5 V), balanced charge carrier mobilities and low threshold voltages. Moreover, the hybrid layers substantially improve the bias stress stability of the transistors compared to those with pure PMMA and HfO{sub x} dielectrics.

  18. The Influence of Perceived Convenience and Curiosity on Continuance Intention in Mobile English Learning for High School Students Using PDAs

    Chang, Chi-Cheng; Tseng, Kuo-Hung; Liang, Chaoyun; Yan, Chi-Fang

    2013-01-01

    Mobile learning aims to utilise communication devices such as mobile devices and wireless connection in combination with e-learning systems, allowing learners to experience convenient, instant and suitable learning at unrestricted time and place. Participants were 125 Taiwanese senior high school students, whose continuance intention was examined…

  19. Barriers and enablers to the use of high-fidelity patient simulation manikins in nurse education: an integrative review.

    Al-Ghareeb, Amal Z; Cooper, Simon J

    2016-01-01

    This integrative review identified, critically appraised and synthesised the existing evidence on the barriers and enablers to using high-fidelity human patient simulator manikins (HPSMs) in undergraduate nursing education. In nursing education, specifically at the undergraduate level, a range of low to high-fidelity simulations have been used as teaching aids. However, nursing educators encounter challenges when introducing new teaching methods or technology, despite the prevalence of high-fidelity HPSMs in nursing education. An integrative review adapted a systematic approach. Medline, CINAHL plus, ERIC, PsychINFO, EMBASE, SCOPUS, Science Direct, Cochrane database, Joanna Brigge Institute, ProQuest, California Simulation Alliance, Simulation Innovative Recourses Center and the search engine Google Scholar were searched. Keywords were selected and specific inclusion/exclusion criteria were applied. The review included all research designs for papers published between 2000 and 2015 that identified the barriers and enablers to using high-fidelity HPSMs in undergraduate nursing education. Studies were appraised using the Critical Appraisal Skills Programme criteria. Thematic analysis was undertaken and emergent themes were extracted. Twenty-one studies were included in the review. These studies adopted quasi-experimental, prospective non-experimental and descriptive designs. Ten barriers were identified, including "lack of time," "fear of technology" and "workload issues." Seven enablers were identified, including "faculty training," "administrative support" and a "dedicated simulation coordinator." Barriers to simulation relate specifically to the complex technologies inherent in high-fidelity HPSMs approaches. Strategic approaches that support up-skilling and provide dedicated technological support may overcome these barriers. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Microstructural characterization of thermal barrier coating on Inconel 617 after high temperature oxidation

    Mohammadreza Daroonparvar

    2013-06-01

    Full Text Available A turbine blade was protected against high temperature corrosion and oxidation by thermal barrier coatings (TBCsusing atmospheric plasma spraying technique (APS on a Ni-based superalloy (Inconel 617. The coatings (NiCr6AlY/ YSZ and NiCr10AlY/YSZ consist of laminar structure with substantial interconnected porosity transferred oxygen from Yittria stabilized Zirconia (YSZ layer toward the bond coat (NiCrAlY. Hence, a thermally grown oxide layer (TGO was formed on the metallic bond coat and internal oxidation of the bond coat occurred during oxidation. The TBC systems were oxidized in a normal electrically heated furnace at 1150 °C for 18, 22, 26, 32 and 40h.Microstructural characterization of coatings demonstrated that the growth of the TGO layer on the nickel alloy with 6wt. % Al is more rapid than TGO with 10wt. % Al. In addition, many micro-cracks were observed at the interface of NiCr6AlY/YSZ. X-ray diffraction analysis (XRD showed the existence of detrimental oxides such as NiCr2O4, NiCrO3 and NiCrO4 in the bond coat containing 6wt. % Al, accompanied by rapid volume expansion causing the destruction of TBC. In contrast, in the bond coat with 10wt. % Al, NiO, Al2O3and Cr2O3 oxides were formed while very low volume expansion occurred. The oxygen could not penetrate into the TGO layer of bond coat with 10 wt. % Al during high temperature oxidation and the detrimental oxides were not extensively formed within the bond coat as more oxygen was needed. The YSZ with higher Al content showed higher oxidation resistance.

  1. Barrier effects of remote high mountain on atmospheric metal transport in the eastern Tibetan Plateau.

    Bing, Haijian; Zhou, Jun; Wu, Yanhong; Luo, Xiaosan; Xiang, Zhongxiang; Sun, Hongyang; Wang, Jipeng; Zhu, He

    2018-07-01

    Anthropogenic metals adsorbed on suspended fine particles can be deposited on remote and inaccessible high mountains by long-range atmospheric transport. In this study, we investigated the cadmium (Cd) and lead (Pb) in the soils, mosses and rainfall of three transects on the Gongga Mountain, eastern Tibetan Plateau, to understand the mountain interception effects on their atmospheric transport. The concentrations of Cd and Pb in the soils and mosses displayed a pattern of eastern transect>northern transect>western transect. The distribution of Cd and Pb on the eastern transect increased from 2000 to 2900m a.s.l. (above sea level), decreased toward the timberline, and increased again with altitude; on the northern transect, it generally decreased with altitude whereas a distribution trend was not clearly observed on the western transect. The Cd and Pb concentrations in the rainfall of the eastern transect generally decreased with altitude, and they were higher inside forests than outside forests and temporally higher in the winter than the summer. The Pb isotopic ratios coupled with moss bio-monitoring distinguished anthropogenic sources of Cd and Pb on the eastern and northern transects, whereas bedrock weathering was the main source of Cd and Pb on the western transect. We proposed a conceptual model to delineate the effects of terrain, local climate and vegetation on the transport of atmospheric metals. Our results highlighted the high mountains in the eastern Tibetan Plateau as an effective natural barrier limiting atmospheric metal transport. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Comparative study of InGaP/GaAs high electron mobility transistors with upper and lower delta-doped supplied layers

    Tsai, Jung-Hui; Ye, Sheng-Shiun; Guo, Der-Feng; Lour, Wen-Shiung

    2012-01-01

    Influence corresponding to the position of δ-doped supplied layer on InGaP/GaAs high electron mobility transistors is comparatively studied by two-dimensional simulation analysis. The simulated results exhibit that the device with lower δ-doped supplied layer shows a higher gate potential barrier height, a higher saturation output current, a larger magnitude of negative threshold voltage, and broader gate voltage swing, as compared to the device with upper δ-doped supplied layer. Nevertheless, it has smaller transconductance and inferior high-frequency characteristics in the device with lower δ-doped supplied layer. Furthermore, a knee effect in current-voltage curves is observed at low drain-to-source voltage in the two devices, which is investigated in this article.

  3. A Comparison of Perceptions of Barriers to Academic Success among High-Ability Students from High- and Low-Income Groups: Exposing Poverty of a Different Kind

    Cross, Jennifer Riedl; Frazier, Andrea Dawn; Kim, Mihyeon; Cross, Tracy L.

    2018-01-01

    In 14 focus group interviews, sixth- to eighth-grade high-ability students from high- (n = 36) and low-income (n = 45) families were asked to describe the barriers they perceived to their academic success. Three themes were identified through the qualitative analysis: "Constraining Environments, Integration versus Isolation," and…

  4. High-resolution charge carrier mobility mapping of heterogeneous organic semiconductors

    Button, Steven W.; Mativetsky, Jeffrey M.

    2017-08-01

    Organic electronic device performance is contingent on charge transport across a heterogeneous landscape of structural features. Methods are therefore needed to unravel the effects of local structure on overall electrical performance. Using conductive atomic force microscopy, we construct high-resolution out-of-plane hole mobility maps from arrays of 5000 to 16 000 current-voltage curves. To demonstrate the efficacy of this non-invasive approach for quantifying and mapping local differences in electrical performance due to structural heterogeneities, we investigate two thin film test systems, one bearing a heterogeneous crystal structure [solvent vapor annealed 5,11-Bis(triethylsilylethynyl)anthradithiophene (TES-ADT)—a small molecule organic semiconductor] and one bearing a heterogeneous chemical composition [p-DTS(FBTTh2)2:PC71BM—a high-performance organic photovoltaic active layer]. TES-ADT shows nearly an order of magnitude difference in hole mobility between semicrystalline and crystalline areas, along with a distinct boundary between the two regions, while p-DTS(FBTTh2)2:PC71BM exhibits subtle local variations in hole mobility and a nanoscale domain structure with features below 10 nm in size. We also demonstrate mapping of the built-in potential, which plays a significant role in organic light emitting diode and organic solar cell operation.

  5. Effects of inositol trisphosphate on calcium mobilization in high-voltage and saponin-permeabilized platelets

    Gear, A.R.L.; Hallam, T.J.

    1986-01-01

    Interest in phosphatidylinositol metabolism has been greatly stimulated by the findings that diglyceride and inositol phosphates may serve as second messengers in modulating cellular function. Formation of 1,4,5-inositol trisphosphate (IP 3 ), in particular, has been linked to mobilization of intracellular calcium in a number of cell types. The authors have examined the ability of IP 3 to mobilize calcium in human platelets permeabilized by either saponin or high-voltage discharge. Saponin at 15 μg/ml effectively permeabilized platelets to exogenous inositol 1,4,5-trisphosphate which released bound [ 45 Ca] within 1 min and with a Ka of 7.4 +/- 4.1 μM. A small (25%) azide-sensitive pool was also responsive to inositol trisphosphate. The calcium pools were completely discharged by A-23187 and the ATP-dependent uptake was prevented by dinitrophenol. In contrast to the result with saponin, platelets accessed by high-voltage discharge were insensitive to challenge by inositol 1,4,5-trisphosphate. The data suggest that while inositol 1,4,5-trisphosphate can rapidly mobilize platelet calcium, the ability to demonstrate this depends on the method of permeabilization

  6. Performance improvement for solution-processed high-mobility ZnO thin-film transistors

    Li Chensha; Loutfy, Rafik O [Department of Chemical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4L7 (Canada); Li Yuning; Wu Yiliang; Ong, Beng S [Materials Design and Integration Laboratory, Xerox Research Centre of Canada, 2660 Speakman Drive, Mississauga, Ontario L5K 2L1 (Canada)], E-mail: lichnsa@163.com

    2008-06-21

    The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

  7. High-field asymmetric waveform ion mobility spectrometry for mass spectrometry-based proteomics.

    Swearingen, Kristian E; Moritz, Robert L

    2012-10-01

    High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an atmospheric pressure ion mobility technique that separates gas-phase ions by their behavior in strong and weak electric fields. FAIMS is easily interfaced with electrospray ionization and has been implemented as an additional separation mode between liquid chromatography (LC) and mass spectrometry (MS) in proteomic studies. FAIMS separation is orthogonal to both LC and MS and is used as a means of on-line fractionation to improve the detection of peptides in complex samples. FAIMS improves dynamic range and concomitantly the detection limits of ions by filtering out chemical noise. FAIMS can also be used to remove interfering ion species and to select peptide charge states optimal for identification by tandem MS. Here, the authors review recent developments in LC-FAIMS-MS and its application to MS-based proteomics.

  8. Performance improvement for solution-processed high-mobility ZnO thin-film transistors

    Li Chensha; Loutfy, Rafik O; Li Yuning; Wu Yiliang; Ong, Beng S

    2008-01-01

    The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process

  9. High Field Asymmetric Waveform Ion Mobility Spectrometry (FAIMS) for Mass Spectrometry-Based Proteomics

    Swearingen, Kristian E.; Moritz, Robert L.

    2013-01-01

    SUMMARY High field asymmetric waveform ion mobility spectrometry (FAIMS) is an atmospheric pressure ion mobility technique that separates gas-phase ions by their behavior in strong and weak electric fields. FAIMS is easily interfaced with electrospray ionization and has been implemented as an additional separation mode between liquid chromatography (LC) and mass spectrometry (MS) in proteomic studies. FAIMS separation is orthogonal to both LC and MS and is used as a means of on-line fractionation to improve detection of peptides in complex samples. FAIMS improves dynamic range and concomitantly the detection limits of ions by filtering out chemical noise. FAIMS can also be used to remove interfering ion species and to select peptide charge states optimal for identification by tandem MS. Here, we review recent developments in LC-FAIMS-MS and its application to MS-based proteomics. PMID:23194268

  10. Highly mobile charge-transfer excitons in two-dimensional WS2/tetracene heterostructures

    Zhu, Tong; Yuan, Long; Zhao, Yan; Zhou, Mingwei; Wan, Yan; Mei, Jianguo; Huang, Libai

    2018-01-01

    Charge-transfer (CT) excitons at heterointerfaces play a critical role in light to electricity conversion using organic and nanostructured materials. However, how CT excitons migrate at these interfaces is poorly understood. We investigate the formation and transport of CT excitons in two-dimensional WS2/tetracene van der Waals heterostructures. Electron and hole transfer occurs on the time scale of a few picoseconds, and emission of interlayer CT excitons with a binding energy of ~0.3 eV has been observed. Transport of the CT excitons is directly measured by transient absorption microscopy, revealing coexistence of delocalized and localized states. Trapping-detrapping dynamics between the delocalized and localized states leads to stretched-exponential photoluminescence decay with an average lifetime of ~2 ns. The delocalized CT excitons are remarkably mobile with a diffusion constant of ~1 cm2 s−1. These highly mobile CT excitons could have important implications in achieving efficient charge separation. PMID:29340303

  11. Advanced thermal barrier coatings for operation in high hydrogen content fueled gas turbines.

    Sampath, Sanjay [Stony Brook Univ., NY (United States)

    2015-04-02

    The Center for Thermal Spray Research (CTSR) at Stony Brook University in partnership with its industrial Consortium for Thermal Spray Technology is investigating science and technology related to advanced metallic alloy bond coats and ceramic thermal barrier coatings for applications in the hot section of gasified coal-based high hydrogen turbine power systems. In conjunction with our OEM partners (GE and Siemens) and through strategic partnership with Oak Ridge National Laboratory (ORNL) (materials degradation group and high temperature materials laboratory), a systems approach, considering all components of the TBC (multilayer ceramic top coat, metallic bond coat & superalloy substrate) is being taken during multi-layered coating design, process development and subsequent environmental testing. Recent advances in process science and advanced in situ thermal spray coating property measurement enabled within CTSR has been incorporated for full-field enhancement of coating and process reliability. The development of bond coat processing during this program explored various aspects of processing and microstructure and linked them to performance. The determination of the bond coat material was carried out during the initial stages of the program. Based on tests conducted both at Stony Brook University as well as those carried out at ORNL it was determined that the NiCoCrAlYHfSi (Amdry) bond coats had considerable benefits over NiCoCrAlY bond coats. Since the studies were also conducted at different cycling frequencies, thereby addressing an associated need for performance under different loading conditions, the Amdry bond coat was selected as the material of choice going forward in the program. With initial investigations focused on the fabrication of HVOF bond coats and the performance of TBC under furnace cycle tests , several processing strategies were developed. Two-layered HVOF bond coats were developed to render optimal balance of density and surface roughness

  12. Design and Characterization of High-strength Bond Coats for Improved Thermal Barrier Coating Durability

    Jorgensen, David John

    High pressure turbine blades in gas turbine engines rely on thermal barrier coating (TBC) systems for protection from the harsh combustion environment. These coating systems consist of a ceramic topcoat for thermal protection, a thermally grown oxide (TGO) for oxidation passivation, and an intermetallic bond coat to provide compatibility between the substrate and ceramic over-layers while supplying aluminum to sustain Al2O 3 scale growth. As turbine engines are pushed to higher operating temperatures in pursuit of better thermal efficiency, the strength of industry-standard bond coats limits the lifetime of these coating systems. Bond coat creep deformation during thermal cycling leads to a failure mechanism termed rumpling. The interlayer thermal expansion differences, combined with TGO-imposed growth stresses, lead to the development of periodic undulations in the bond coat. The ceramic topcoat has low out-of-plane compliance and thus detaches and spalls from the substrate, resulting in a loss of thermal protection and subsequent degradation of mechanical properties. New creep resistant Ni3Al bond coats were designed with improved high-temperature strength to inhibit this type of premature failure at elevated temperatures. These coatings resist rumpling deformation while maintaining compatibility with the other layers in the system. Characterization methods are developed to quantify rumpling and assess the TGO-bond coat interface toughness of experimental systems. Cyclic oxidation experiments at 1163 °C show that the Ni3Al bond coats do not experience rumpling but have faster oxide growth rates and are quicker to spall TGO than the (Pt,Ni)Al benchmark. However, the Ni 3Al coatings outperformed the benchmark by over threefold in TBC system life due to a higher resistance to rumpling (mechanical degradation) while maintaining adequate oxidation passivation. The Ni3Al coatings eventually grow spinel NiAl2O4 on top of the protective Al2O3 layer, which leads to the

  13. Aspects of High-Q Tunable Antennas and Their Deployment for 4G Mobile Communications

    Bahramzy, Pevand; Jagielski, Ole; Svendsen, Simon

    2016-01-01

    Tunable antennas are very promising for future generations of mobile communications, where broad frequency coverage will be required increasingly. This work describes the design of small high-Quality factor (Q) tunable antennas based on Micro-Electro-Mechanical Systems (MEMS), which are capable...... of operation in the frequency ranges 600 - 960 MHz and 1710 - 2690 MHz. Some aspects of high-Q tunable antennas are investigated through experimental measurements and the result are presented. Results show that more than -30 dB of isolation can be achieved between the Transmit (Tx) and Receive (Rx) antennas...

  14. Investigation of the High Mobility IGZO Thin Films by Using Co-Sputtering Method

    Hsu, Chao-Ming; Tzou, Wen-Cheng; Yang, Cheng-Fu; Liou, Yu-Jhen

    2015-01-01

    High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO) ceramic and In2O3 ceramic at the same time. The deposition power of pure In2O3 ceramic target was fixed at 100 W and the deposition power of GZO ceramic target was changed from 80 W to 140 W. We chose to investigate the deposition power of GZO ceramic target on the properties of IGZO thin films. From the...

  15. The operation cutoff frequency of high electron mobility transistor measured by terahertz method

    Zhu, Y. M.; Zhuang, S. L.

    2014-01-01

    Commonly, the cutoff frequency of high electron mobility transistor (HEMT) can be measured by vector network analyzer (VNA), which can only measure the sample exactly in low frequency region. In this paper, we propose a method to evaluate the cutoff frequency of HEMT by terahertz (THz) technique. One example shows the cutoff frequency of our HEMT is measured at ∼95.30 GHz, which is reasonable agreement with that estimated by VNA. It is proved THz technology a potential candidate for the substitution of VNA for the measurement of high-speed devices even up to several THz.

  16. Increase in electron mobility of InGaAs/InP composite channel high electron mobility transistor structure due to SiN passivation

    Liu Yuwei; Wang Hong; Radhakrishnan, K.

    2007-01-01

    The influence of silicon nitride passivation on electron mobility of InGaAs/InP composite channel high electron mobility transistor structure has been studied. Different from the structures with single InGaAs channel, an increase in effective mobility μ e with a negligible change of sheet carrier density n s after SiN deposition is clearly observed in the composite channel structures. The enhancement of μ e could be explained under the framework of electrons transferring from the InP sub-channel into InGaAs channel region due to the energy band bending at the surface region caused by SiN passivation, which is further confirmed by low temperature photoluminescence measurements

  17. A possible high-mobility signal in bulk MoTe2: Temperature independent weak phonon decay

    Titao Li

    2016-11-01

    Full Text Available Layered transition metal dichalcogenides (TMDs have attracted great attention due to their non-zero bandgap for potential application in high carrier mobility devices. Recent studies demonstrate that the carrier mobility of MoTe2 would decrease by orders of magnitude when used for few-layer transistors. As phonon scattering has a significant influence on carrier mobility of layered material, here, we first reported temperature-dependent Raman spectra of bulk 2H-MoTe2 from 80 to 300 K and discovered that the phonon lifetime of both E12g and A1g vibration modes are independent with temperature. These results were explained by the weak phonon decay in MoTe2. Our results imply the existence of a carrier mobility higher than the theoretical value in intrinsic bulk 2H-MoTe2 and the feasibility to obtain MoTe2-based transistors with sufficiently high carrier mobility.

  18. Environmental settings and families' socioeconomic status influence mobility and the use of mobility devices by children with cerebral palsy

    Valéria C. R. Cury

    Full Text Available Functional mobility of children with cerebral palsy (CP is influenced by personal and environmental factors, serving as barriers and/or facilitators and impacting on children's strategies and functional outcome. OBJECTIVES: To describe typical mobility methods used by children with CP at home, school and community and to compare them across family's socioeconomic levels (SES. METHODS: The Functional Mobility Scale was used to assess mobility of 113 children with CP of high and low SES at home, school, and community. RESULTS: Differences in mobility methods of participants classified as Gross Motor Function Classification System levels II, III and IV were found between home and community. For levels III and IV, differences were also found between home and school. At home, participants from higher SES used wheelchairs more frequently while those from lower SES used floor mobility (crawling. CONCLUSIONS: Environmental settings and families' socioeconomic status influence mobility and use of mobility devices by children with CP.

  19. DESIGN APPLICATIONS BASED ON WEB MOBILE AT GAYA BARU SENIOR HIGH SCHOOL, CENTRAL LAMPUNG REGENCY AS PROMOTIONAL MEDIA

    Ahmad Yudi

    2017-05-01

    Full Text Available Gaya Baru Senior High School is one of the educational institutions in Lampung which is a less favorite institution in the area is precisely located in the district of Seputih Surabaya Central Lampung Regency. Gaya Baru Senior High School has already had a website but not many known. This Senior High School is also no information system through mobile web to promote the institution. Nevertheless, in its development, students or community want to find information about the school can be directly through the mobile web application. So in its development requires fast service. From research that conducted in Gaya Baru High School, existence of new mobile web application system will facilitate student or society of that area, especially in subdistrict Seputih Surabaya district Central Lampung, and present information about the info about situation in high school of new style it can be accessed directly through the mobile web media.

  20. Determinants of High Blood Pressure and Barriers to Diagnosis and Treatment in Dar es Salaam, Tanzania

    ZACK, Rachel M.; IREMA, Kahema; KAZONDA, Patrick; LEYNA, Germana H.; LIU, Enju; SPIEGELMAN, Donna; FAWZI, Wafaie; NJELEKELA, Marina; KILLEWO, Japhet; DANAEI, Goodarz

    2017-01-01

    Objectives We assessed prevalence and determinants of high blood pressure, and barriers to diagnosis and treatment, in Dar es Salaam, Tanzania. Methods We surveyed and screened 2,174 community-dwelling adults aged ≥40 years in 2014 and conducted a follow-up after one year. Results Median blood pressure was 131/81 mmHg and hypertension prevalence was 37%. Mean adjusted difference in SBP was 4.0 mmHg for overweight, 6.3 mmHg for obese class I, and 10.5 mmHg for obese class II/III compared with normal weight participants. Those who were physically inactive had 4.8 mmHg higher SBP compared to those with more than 24 hours of moderate or vigorous activity per week. Drinkers of at least 10 grams of alcohol per day had 4.5 mmHg higher SBP than did non-drinkers. Among hypertensives, 48% were diagnosed, 22% were treated, and 10% were controlled. Hypertensives without health insurance were 12% less likely to be diagnosed than insured hypertensives. Of referred participants, 68% sought care, but only 27% were on treatment and 8% had controlled blood pressure at follow-up. Reasons for not seeking care included lack of symptoms, cost of visit, and lack of time. Reasons for not being on treatment included lack of symptoms, not being prescribed treatment, and having finished one course of treatment. Conclusions Major risk factors for hypertension in Dar es Salaam are overweight, obesity, inadequate physical activity, and limited access to quality medical care. Increased insurance coverage and community-based screening, along with quality medical care and patient education, may help control this burgeoning epidemic. PMID:27648720

  1. Corrosion of high purity copper as engineering barrier in deep geological repositories

    Ochoa, Maité; Rodríguez Martín, A.; Farina Silvia, B.

    2013-01-01

    Pure copper with oxygen content below 5 ppm (to minimize segregation at grain boundaries) and doped with phosphorus (to increase creep resistance) is the chosen material for the corrosion-resistant barrier of the High Level Radioactive 2 Wastecontainers in the Swedish and Finnish repository models. These models include the construction of the repository below the water table, which is a reducing environment in which copper has excellent resistance to general and localized corrosion in aqueous electrolytes. The aim of this work is contribute to determine the durability of the material, given that deep geological repositories of HLW are designed to ensure the protection of the environment for periods of hundreds of thousands years. As a first step in a more general analysis the effects of chloride, one of the main aggressive species of corrosion, are evaluated. To this purpose corrosion potential was determined and anodic polarization curves were performed in deaerated solutions varying the chloride concentration between 0.01 and 1M and the temperature between 30 and 90°C. Several electrochemical techniques were used: the evolution of corrosion potential was measured, anodic polarization curves were obtained and electrochemical impedance tests were performed. The analysis was complemented with microscopic observations of the type of corrosive attack, as well as determinations of the eventual corrosion products formed using Energy-Dispersive X-ray Analysis (EDS). Results show that the corrosion potential decreases with the increase of temperature and with the increase of chloride concentration. A correlation of the corrosion potential as a function of temperature and chloride concentration was obtained, with the purpose of making predictions in variable conditions.The current density increases both with temperature and with chloride concentration. A pitting potential is observed in certain conditions. (author)

  2. Mobility decline in old age

    Rantakokko, Merja; Mänty, Minna Regina; Rantanen, Taina

    2013-01-01

    Mobility is important for community independence. With increasing age, underlying pathologies, genetic vulnerabilities, physiological and sensory impairments, and environmental barriers increase the risk for mobility decline. Understanding how mobility declines is paramount to finding ways...... to promote mobility in old age....

  3. Motivations and barriers to the adoption of 3G mobile multimedia services: an end-user perspective in the Italian market

    M. Pagani

    2003-01-01

    In this paper we review user information technology acceptance literature, formulate a model of consumer adoption of third generation mobile multimedia services. The results show that erceived usefulness, ease of use, price and speed of use are the most important determinants of adoption of multimedia mobile services.

  4. Investigation of high mobility pseudomorphic SiGe p-channels in Si MOSFETS at low and high electric fields

    Palmer, Martin John

    2001-01-01

    Silicon Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs) for high speed, high current applications are rapidly approaching the physical and financial limits of the technology. This opens opportunities for the incorporation of materials with intrinsically better transport characteristics. An alloy of silicon and germanium is one such material that is gaining much recognition as the active component of MOSFETs and as the secondary structures (such as the gate electrode). This work examines a batch of buried channel Si 0.64 Ge 0.36 p-MOSFETs, with a minimum effective length of 0.35 μm, under different bias conditions and at different temperatures. High current and transconductance enhancements are apparent at long gate lengths. The carrier mobility is up to a factor of 2.5 times that of silicon at room temperature and 7.5 times at 4 K. A clear trend of decreasing peak mobility with decreasing silicon cap thickness is evident. Simulations show that scattering caused by the roughness of the SiO 2 /Si interface dominates, rather than alloy scattering or Si/SiGe roughness, even for a buried channel. This scattering increases with the proximity of the carriers to the interface. An increase of interface trap density with decreasing cap thickness, demonstrates that segregated germanium exists some distance into the cap and interferes with the oxidation process. This will increase scattering through increased SiO 2 /Si roughness and increased trapped charge. The short channel, high field results are comparable or slightly worse than those of silicon due to lower saturation drift velocity. However, fitting to a drift-diffusion model shows an apparent increase in saturation velocity for short channels, especially at low temperatures. This effect correlates with the low field mobility and is greater for devices containing SiGe. This is an indication of velocity overshoot, which may enhance the performance of SiGe MOSFETs at deep submicron gate lengths. (author)

  5. Low Thermal Conductivity, High Durability Thermal Barrier Coatings for IGCC Environments

    Jordan, Eric [Univ. of Connecticut, Storrs, CT (United States); Gell, Maurice [Univ. of Connecticut, Storrs, CT (United States)

    2015-01-15

    Advanced thermal barrier coatings (TBC) are crucial to improved energy efficiency in next generation gas turbine engines. The use of traditional topcoat materials, e.g. yttria-stabilized zirconia (YSZ), is limited at elevated temperatures due to (1) the accelerated undesirable phase transformations and (2) corrosive attacks by calcium-magnesium-aluminum-silicate (CMAS) deposits and moisture. The first goal of this project is to use the Solution Precursor Plasma Spray (SPPS) process to further reduce the thermal conductivity of YSZ TBCs by introducing a unique microstructural feature of layered porosity, called inter-pass boundaries (IPBs). Extensive process optimization accompanied with hundreds of spray trials as well as associated SEM cross-section and laser-flash measurements, yielded a thermal conductivity as low as 0.62 Wm⁻¹K⁻¹ in SPPS YSZ TBCs, approximately 50% reduction of APS TBCs; while other engine critical properties, such as cyclic durability, erosion resistance and sintering resistance, were characterized to be equivalent or better than APS baselines. In addition, modifications were introduced to SPPS TBCs so as to enhance their resistance to CMAS under harsh IGCC environments. Several mitigation approaches were explored, including doping the coatings with Al₂O₃ and TiO₂, applying a CMAS infiltration-inhibiting surface layer, and filling topcoat cracks with blocking substances. The efficacy of all these modifications was assessed with a set of novel CMAS-TBC interaction tests, and the moisture resistance was tested in a custom-built high-temperature moisture rig. In the end, the optimal low thermal conductivity TBC system was selected based on all evaluation tests and its processing conditions were documented. The optimal coating consisted on a thick inner layer of YSZ coating made by the SPPS process having a thermal conductivity 50% lower than standard YSZ coatings topped with a high temperature tolerant CMAS resistant gadolinium

  6. High mobility AlGaN/GaN devices for β{sup −}-dosimetry

    Schmid, Martin; Howgate, John; Ruehm, Werner [Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg (Germany); Thalhammer, Stefan, E-mail: stefan.thalhammer@physik.uni-augsburg.de [Universität Augsburg, Universitätsstraße 1, 86159 Augsburg (Germany)

    2016-05-21

    There is a high demand in modern medical applications for dosimetry sensors with a small footprint allowing for unobtrusive or high spatial resolution detectors. To this end we characterize the sensoric response of radiation resistant high mobility AlGaN/GaN semiconductor devices when exposed to β{sup −}-emitters. The samples were operated as a floating gate transistor, without a field effect gate electrode, thus excluding any spurious effects from β{sup −}-particle interactions with a metallic surface covering. We demonstrate that the source–drain current is modulated in dependence on the kinetic energy of the incident β{sup −}-particles. Here, the signal is shown to have a linear dependence on the absorbed energy calculated from Monte Carlo simulations. Additionally, a stable and reproducible sensor performance as a β{sup −}-dose monitor is shown for individual radioisotopes. Our experimental findings and the characteristics of the AlGaN/GaN high mobility layered devices indicate their potential for future applications where small sensor size is necessary, like for instance brachytherapy.

  7. High mobility AlGaN/GaN devices for β"−-dosimetry

    Schmid, Martin; Howgate, John; Ruehm, Werner; Thalhammer, Stefan

    2016-01-01

    There is a high demand in modern medical applications for dosimetry sensors with a small footprint allowing for unobtrusive or high spatial resolution detectors. To this end we characterize the sensoric response of radiation resistant high mobility AlGaN/GaN semiconductor devices when exposed to β"−-emitters. The samples were operated as a floating gate transistor, without a field effect gate electrode, thus excluding any spurious effects from β"−-particle interactions with a metallic surface covering. We demonstrate that the source–drain current is modulated in dependence on the kinetic energy of the incident β"−-particles. Here, the signal is shown to have a linear dependence on the absorbed energy calculated from Monte Carlo simulations. Additionally, a stable and reproducible sensor performance as a β"−-dose monitor is shown for individual radioisotopes. Our experimental findings and the characteristics of the AlGaN/GaN high mobility layered devices indicate their potential for future applications where small sensor size is necessary, like for instance brachytherapy.

  8. Study on characteristics of high frequency dielectric barrier discharge for the removal of organic pollutant adsorbed on activated carbon

    Qu, G.Z.; Li, G.F. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Li, J.; Lu, N.; Wu, Y.; Li, D. [Dalian Univ. of Technology, Dalian (China). Inst. of Electrostatics and Special Power; Key Lab of Industrial Ecology and Environmental Engineering, Ministry of Education, Dalian (China)

    2010-07-01

    Advanced oxidation technologies such as photocatalysis, electrochemical degradation, Fenton oxidation, hydrogen peroxide oxidation, and plasma oxidation are increasingly being used to degrade refractory biodegradable organic contaminants. The plasma oxidation method has the advantage of direct in situ production of multiple types of high-reactive chemical species, including molecules and radicals that facilitate the degradation reaction. In addition, plasma oxidation does not produce any secondary pollution. Compared to other plasma technologies, the dielectric barrier discharge (DBD) plasma has been considered as a promising technology for removing toxic compounds because of its stability and its treatability property of biologically recalcitrant compounds in wastewater. However, the energy efficiency of DBD requires improvement for economic reasons. This paper reported on an experimental study that investigated the electrical characteristics of a parallel plate DBD reactor using a high frequency power supply for the removal of pentachlorophenol (PCP) adsorbed on activated carbon (AC). This study examined the effects of AC with different mass on discharge characteristics and compared the voltage and current waveforms, and discharge images of DBD reactors with different dielectric configurations. When the DBD reactor filled with AC, the applied voltage of discharge decreased regardless of the DBD reactor configuration in terms of having a single barrier or two barriers. The discharge characteristics had no significant change with AC mass increasing. The discharge images and current waveforms showed that DBD reactor configuration consisting of two dielectrics is more homogeneous and stable than the one consisting of a single dielectric. Under the same electric field condition, the degradation efficiency of PCP in two barriers reactor is higher than that in single barrier reactor. It was concluded that the findings from this study may be instrumental in treating

  9. Identification of multi-drug resistant Pseudomonas aeruginosa clinical isolates that are highly disruptive to the intestinal epithelial barrier

    Shevchenko Olga

    2006-06-01

    Full Text Available Abstract Background Multi-drug resistant Pseudomonas aeruginosa nosocomial infections are increasingly recognized worldwide. In this study, we focused on the virulence of multi-drug resistant clinical strains P. aeruginosa against the intestinal epithelial barrier, since P. aeruginosa can cause lethal sepsis from within the intestinal tract of critically ill and immuno-compromised patients via mechanisms involving disruption of epithelial barrier function. Methods We screened consecutively isolated multi-drug resistant P. aeruginosa clinical strains for their ability to disrupt the integrity of human cultured intestinal epithelial cells (Caco-2 and correlated these finding to related virulence phenotypes such as adhesiveness, motility, biofilm formation, and cytotoxicity. Results Results demonstrated that the majority of the multi-drug resistant P. aeruginosa clinical strains were attenuated in their ability to disrupt the barrier function of cultured intestinal epithelial cells. Three distinct genotypes were found that displayed an extreme epithelial barrier-disrupting phenotype. These strains were characterized and found to harbor the exoU gene and to display high swimming motility and adhesiveness. Conclusion These data suggest that detailed phenotypic analysis of the behavior of multi-drug resistant P. aeruginosa against the intestinal epithelium has the potential to identify strains most likely to place patients at risk for lethal gut-derived sepsis. Surveillance of colonizing strains of P. aeruginosa in critically ill patients beyond antibiotic sensitivity is warranted.

  10. Breakdown mechanisms in AlGaN/GaN high electron mobility transistors with different GaN channel thickness values

    Ma Xiao-Hua; Zhang Ya-Man; Chen Wei-Wei; Wang Xin-Hua; Yuan Ting-Ting; Pang Lei; Liu Xin-Yu

    2015-01-01

    In this paper, the off-state breakdown characteristics of two different AlGaN/GaN high electron mobility transistors (HEMTs), featuring a 50-nm and a 150-nm GaN thick channel layer, respectively, are compared. The HEMT with a thick channel exhibits a little larger pinch-off drain current but significantly enhanced off-state breakdown voltage (BV off ). Device simulation indicates that thickening the channel increases the drain-induced barrier lowering (DIBL) but reduces the lateral electric field in the channel and buffer underneath the gate. The increase of BV off in the thick channel device is due to the reduction of the electric field. These results demonstrate that it is necessary to select an appropriate channel thickness to balance DIBL and BV off in AlGaN/GaN HEMTs. (paper)

  11. Dedicated mobile high resolution prostate PET imager with an insertable transrectal probe

    Majewski, Stanislaw; Proffitt, James

    2010-12-28

    A dedicated mobile PET imaging system to image the prostate and surrounding organs. The imaging system includes an outside high resolution PET imager placed close to the patient's torso and an insertable and compact transrectal probe that is placed in close proximity to the prostate and operates in conjunction with the outside imager. The two detector systems are spatially co-registered to each other. The outside imager is mounted on an open rotating gantry to provide torso-wide 3D images of the prostate and surrounding tissue and organs. The insertable probe provides closer imaging, high sensitivity, and very high resolution predominately 2D view of the prostate and immediate surroundings. The probe is operated in conjunction with the outside imager and a fast data acquisition system to provide very high resolution reconstruction of the prostate and surrounding tissue and organs.

  12. N-polar GaN epitaxy and high electron mobility transistors

    Wong, Man Hoi; Keller, Stacia; Dasgupta, Nidhi Sansaptak; Denninghoff, Daniel J; Kolluri, Seshadri; Brown, David F; Lu, Jing; Fichtenbaum, Nicholas A; Ahmadi, Elaheh; DenBaars, Steven P; Speck, James S; Mishra, Umesh K; Singisetti, Uttam; Chini, Alessandro; Rajan, Siddharth

    2013-01-01

    This paper reviews the progress of N-polar (0001-bar) GaN high frequency electronics that aims at addressing the device scaling challenges faced by GaN high electron mobility transistors (HEMTs) for radio-frequency and mixed-signal applications. Device quality (Al, In, Ga)N materials for N-polar heterostructures are developed using molecular beam epitaxy and metalorganic chemical vapor deposition. The principles of polarization engineering for designing N-polar HEMT structures will be outlined. The performance, scaling behavior and challenges of microwave power devices as well as highly-scaled depletion- and enhancement-mode devices employing advanced technologies including self-aligned processes, n+ (In,Ga)N ohmic contact regrowth and high aspect ratio T-gates will be discussed. Recent research results on integrating N-polar GaN with Si for prospective novel applications will also be summarized. (invited review)

  13. Non-thermal activation of the hsp27/p38MAPK stress pathway by mobile phone radiation in human endothelial cells: molecular mechanism for cancer- and blood-brain barrier-related effects.

    Leszczynski, Dariusz; Joenväärä, Sakari; Reivinen, Jukka; Kuokka, Reetta

    2002-05-01

    We have examined whether non-thermal exposures of cultures of the human endothelial cell line EA.hy926 to 900 MHz GSM mobile phone microwave radiation could activate stress response. Results obtained demonstrate that 1-hour non-thermal exposure of EA.hy926 cells changes the phosphorylation status of numerous, yet largely unidentified, proteins. One of the affected proteins was identified as heat shock protein-27 (hsp27). Mobile phone exposure caused a transient increase in phosphorylation of hsp27, an effect which was prevented by SB203580, a specific inhibitor of p38 mitogen-activated protein kinase (p38MAPK). Also, mobile phone exposure caused transient changes in the protein expression levels of hsp27 and p38MAPK. All these changes were non-thermal effects because, as determined using temperature probes, irradiation did not alter the temperature of cell cultures, which remained throughout the irradiation period at 37 +/- 0.3 degrees C. Changes in the overall pattern of protein phosphorylation suggest that mobile phone radiation activates a variety of cellular signal transduction pathways, among them the hsp27/p38MAPK stress response pathway. Based on the known functions of hsp27, we put forward the hypothesis that mobile phone radiation-induced activation of hsp27 may (i) facilitate the development of brain cancer by inhibiting the cytochrome c/caspase-3 apoptotic pathway and (ii) cause an increase in blood-brain barrier permeability through stabilization of endothelial cell stress fibers. We postulate that these events, when occurring repeatedly over a long period of time, might become a health hazard because of the possible accumulation of brain tissue damage. Furthermore, our hypothesis suggests that other brain damaging factors may co-participate in mobile phone radiation-induced effects.

  14. High-level waste tank modifications, installation of mobilization equipment/check out

    Schiffhauer, M.A.; Thompson, S.C.

    1992-01-01

    PUREX high-level waste (HLW) is contained at the West Valley Demonstration Project (WVDP) in an underground carbon-steel storage tank. The HLW consists of a precipitated sludge and an alkaline supernate. This report describes the system that the WVDP has developed and implemented to resuspend and wash the HLW sludge from the tank. The report discusses Sludge Mobilization and Wash System (SMWS) equipment design, installation, and testing. The storage tank required modifications to accommodate the SMWS. These modifications are discussed as well

  15. Conductance fluctuations in high mobility monolayer graphene: Nonergodicity, lack of determinism and chaotic behavior.

    da Cunha, C R; Mineharu, M; Matsunaga, M; Matsumoto, N; Chuang, C; Ochiai, Y; Kim, G-H; Watanabe, K; Taniguchi, T; Ferry, D K; Aoki, N

    2016-09-09

    We have fabricated a high mobility device, composed of a monolayer graphene flake sandwiched between two sheets of hexagonal boron nitride. Conductance fluctuations as functions of a back gate voltage and magnetic field were obtained to check for ergodicity. Non-linear dynamics concepts were used to study the nature of these fluctuations. The distribution of eigenvalues was estimated from the conductance fluctuations with Gaussian kernels and it indicates that the carrier motion is chaotic at low temperatures. We argue that a two-phase dynamical fluid model best describes the transport in this system and can be used to explain the violation of the so-called ergodic hypothesis found in graphene.

  16. Mobile Workforce, Mobile Technology, Mobile Threats

    Garcia, J.

    2015-01-01

    Mobile technologies' introduction into the world of safeguards business processes such as inspection creates tremendous opportunity for novel approaches and could result in a number of improvements to such processes. Mobile applications are certainly the wave of the future. The success of the application ecosystems has shown that users want full fidelity, highly-usable, simple purpose applications with simple installation, quick responses and, of course, access to network resources at all times. But the counterpart to opportunity is risk, and the widespread adoption of mobile technologies requires a deep understanding of the threats and vulnerabilities inherent in mobile technologies. Modern mobile devices can be characterized as small computers. As such, the threats against computing infrastructure apply to mobile devices. Meanwhile, the attributes of mobile technology that make it such an obvious benefit over traditional computing platforms all have elements of risk: pervasive, always-on networking; diverse ecosystems; lack of centralized control; constantly shifting technological foundations; intense competition among competitors in the marketplace; the scale of the installation base (from millions to billions); and many more. This paper will explore the diverse and massive environment of mobile, the number of attackers and vast opportunities for compromise. The paper will explain how mobile devices prove valuable targets to both advanced and persistent attackers as well as less-skilled casual hackers. Organized crime, national intelligence agencies, corporate espionage are all part of the landscape. (author)

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

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

    2015-02-23

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

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

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

    2015-01-01

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

  19. Appendicectomies in Albanians in Greece: outcomes in a highly mobile immigrant patient population

    2001-01-01

    Background Albanian immigrants in Greece comprise a highly mobile population with unknown health care profile. We aimed to assess whether these immigrants were more or less likely to undergo laparotomy for suspected appendicitis with negative findings (negative appendicectomy), by performing a controlled study with individual (1:4) matching. We used data from 6 hospitals in the Greek prefecture of Epirus that is bordering Albania. Results Among a total of 2027 non-incidental appendicectomies for suspected appendicitis performed in 1994-1999, 30 patients with Albanian names were matched (for age, sex, time of operation and hospital) to 120 patients with Greek names. The odds for a negative appendicectomy were 3.4-fold higher (95% confidence interval [CI], 1.24-9.31, p = 0.02) in Albanian immigrants than in matched Greek-name subjects. The difference was most prominent in men (odds ratio 20.0, 95% CI, 1.41-285, p = 0.02) while it was not formally significant in women (odds ratio 1.56, 95% CI, 0.44-5.48). The odds for perforation were 1.25-fold higher in Albanian-name immigrants than in Greek-name patients (95% CI 0.44- 3.57). Conclusions Albanian immigrants in Greece are at high risk for negative appendicectomies. Socioeconomic, cultural and language parameters underlying health care inequalities in highly mobile immigrant populations need better study. PMID:11472640

  20. Synergetic aspects of gas-discharge: lateral patterns in dc systems with a high ohmic barrier

    Purwins, H.-G.; Stollenwerk, L.

    2014-12-01

    The understanding of self-organized patterns in spatially extended nonlinear dissipative systems is one of the most challenging subjects in modern natural sciences. Such patterns are also referred to as dissipative structures. We review this phenomenon in planar low temperature dc gas-discharge devices with a high ohmic barrier. It is demonstrated that for these systems a deep qualitative understanding of dissipative structures can be obtained from the point of view of synergetics. At the same time, a major contribution can be made to the general understanding of dissipative structures. The discharge spaces of the experimentally investigated systems, to good approximation, have translational and rotational symmetry by contraction. Nevertheless, a given system may exhibit stable current density distributions and related patterns that break these symmetries. Among the experimentally observed fundamental patterns one finds homogeneous isotropic states, fronts, periodic patterns, labyrinth structures, rotating spirals, target patterns and localized filaments. In addition, structures are observed that have the former as elementary building blocks. Finally, defect structures as well as irregular patterns are common phenomena. Such structures have been detected in numerous other driven nonlinear dissipative systems, as there are ac gas-discharge devices, semiconductors, chemical solutions, electrical networks and biological systems. Therefore, from the experimental observations it is concluded that the patterns in planar low temperature dc gas-discharge devices exhibit universal behavior. From the theoretical point of view, dissipative structures of the aforementioned kind are also referred to as attractors. The possible sets of attractors are an important characteristic of the system. The number and/or qualitative nature of attractors may change when changing parameters. The related bifurcation behavior is a central issue of the synergetic approach chosen in the present

  1. Synergetic aspects of gas-discharge: lateral patterns in dc systems with a high ohmic barrier

    Purwins, H-G; Stollenwerk, L

    2014-01-01

    The understanding of self-organized patterns in spatially extended nonlinear dissipative systems is one of the most challenging subjects in modern natural sciences. Such patterns are also referred to as dissipative structures. We review this phenomenon in planar low temperature dc gas-discharge devices with a high ohmic barrier. It is demonstrated that for these systems a deep qualitative understanding of dissipative structures can be obtained from the point of view of synergetics. At the same time, a major contribution can be made to the general understanding of dissipative structures. The discharge spaces of the experimentally investigated systems, to good approximation, have translational and rotational symmetry by contraction. Nevertheless, a given system may exhibit stable current density distributions and related patterns that break these symmetries. Among the experimentally observed fundamental patterns one finds homogeneous isotropic states, fronts, periodic patterns, labyrinth structures, rotating spirals, target patterns and localized filaments. In addition, structures are observed that have the former as elementary building blocks. Finally, defect structures as well as irregular patterns are common phenomena. Such structures have been detected in numerous other driven nonlinear dissipative systems, as there are ac gas-discharge devices, semiconductors, chemical solutions, electrical networks and biological systems. Therefore, from the experimental observations it is concluded that the patterns in planar low temperature dc gas-discharge devices exhibit universal behavior. From the theoretical point of view, dissipative structures of the aforementioned kind are also referred to as attractors. The possible sets of attractors are an important characteristic of the system. The number and/or qualitative nature of attractors may change when changing parameters. The related bifurcation behavior is a central issue of the synergetic approach chosen in the present

  2. Barriers impeding serologic screening for celiac disease in clinically high-prevalence populations

    2014-01-01

    Background Celiac disease is present in ~1% of the general population in the United States and Europe. Despite the availability of inexpensive serologic screening tests, ~85% of individuals with celiac disease remain undiagnosed and there is an average delay in diagnosis of symptomatic individuals with celiac disease that ranges from ~5.8-11 years. This delay is often attributed to the use of a case-based approach for detection rather than general population screening for celiac disease, and deficiencies at the level of health care professionals. This study aimed to assess if patient-centered barriers have a role in impeding serologic screening for celiac disease in individuals from populations that are clinically at an increased risk for celiac disease. Methods 119 adults meeting study inclusion criteria for being at a higher risk for celiac disease were recruited from the general population. Participants completed a survey/questionnaire at the William K. Warren Medical Research Center for Celiac Disease that addressed demographic information, celiac disease related symptoms (gastrointestinal and extraintestinal), family history, co-morbid diseases and conditions associated with celiac disease, and patient-centered barriers to screening for celiac disease. All participants underwent serologic screening for celiac disease using the IgA tissue transglutaminase antibody (IgA tTG) and, if positive, testing for IgA anti-endomysial antibody (IgA EMA) as a confirmatory test. Results Two barriers to serologic testing were significant across the participant pool. These were participants not knowing they were at risk for celiac disease before learning of the study, and participants not knowing where to get tested for celiac disease. Among participants with incomes less than $25,000/year and those less than the median age, not having a doctor to order the test was a significant barrier, and this strongly correlated with not having health insurance. Symptoms and co

  3. Barriers to adherence to highly active antiretroviral therapy as expressed by people living with HIV/AIDS.

    Proctor, V E; Tesfa, A; Tompkins, D C

    1999-09-01

    The primary objective of this study was to gain a clearer understanding of the barriers to adherence to highly active antiretroviral therapy (HAART) faced by people living with HIV/AIDS (PLWHIV/AIDS) on Long Island, New York. Focus group, a qualitative research method, was used to study these barriers. The study was conducted in 1998 on Long Island, NY, at five institutions that provide services to 1700 PLWHIV/AIDS. Five focus groups were conducted with 6 to 13 PLWHIV/AIDS in each group, a total of 39 subjects. PLWHIV/AIDS identified eight common barriers to adherence to HAART. In descending order, the barriers include: (1) frequency and severity of side effects, (2) conflicts with daily routines, (3) dietary requirements, (4) frequency of taking medications, (5) number and dosage of medications, (6) psychosocial factors (i.e., stress, feeling good, and bad news), (7) pharmacy refills, and (8) physiological needs (i.e., sleep, hunger, or thirst). Many factors play a role in the success or failure of HAART, including preexisting drug resistance, drug-drug interactions, and the ability of PLWHIV/AIDS to adhere to a rigid and frequently changing medication regimen. The information gleaned from focus groups is limited in that it may not be generalized to a larger population with any known reliability. However, clinicians sensitive to barriers to adherence to HAART, including those identified by PLWHIV/AIDS in this study, may play a more proactive role in supporting adherence to the medication regimen, increasing the durability of effective viral suppression, decreasing morbidity and mortality, and decreasing the selection and transmission of resistant strains of HIV.

  4. Automatic camera to laser calibration for high accuracy mobile mapping systems using INS

    Goeman, Werner; Douterloigne, Koen; Gautama, Sidharta

    2013-09-01

    A mobile mapping system (MMS) is a mobile multi-sensor platform developed by the geoinformation community to support the acquisition of huge amounts of geodata in the form of georeferenced high resolution images and dense laser clouds. Since data fusion and data integration techniques are increasingly able to combine the complementary strengths of different sensor types, the external calibration of a camera to a laser scanner is a common pre-requisite on today's mobile platforms. The methods of calibration, nevertheless, are often relatively poorly documented, are almost always time-consuming, demand expert knowledge and often require a carefully constructed calibration environment. A new methodology is studied and explored to provide a high quality external calibration for a pinhole camera to a laser scanner which is automatic, easy to perform, robust and foolproof. The method presented here, uses a portable, standard ranging pole which needs to be positioned on a known ground control point. For calibration, a well studied absolute orientation problem needs to be solved. In many cases, the camera and laser sensor are calibrated in relation to the INS system. Therefore, the transformation from camera to laser contains the cumulated error of each sensor in relation to the INS. Here, the calibration of the camera is performed in relation to the laser frame using the time synchronization between the sensors for data association. In this study, the use of the inertial relative movement will be explored to collect more useful calibration data. This results in a better intersensor calibration allowing better coloring of the clouds and a more accurate depth mask for images, especially on the edges of objects in the scene.

  5. Significant performance enhancement in AlGaN/GaN high electron mobility transistor by high-κ organic dielectric

    Ze-Gao, Wang; Yuan-Fu, Chen; Cao, Chen; Ben-Lang, Tian; Fu-Tong, Chu; Xing-Zhao, Liu; Yan-Rong, Li

    2010-01-01

    The electrical properties of AlGaN/GaN high electron mobility transistor (HEMT) with and without high-κ organic dielectrics are investigated. The maximum drain current I D max and the maximum transconductance g m max of the organic dielectric/AlGaN/GaN structure can be enhanced by 74.5%, and 73.7% compared with those of the bare AlGaN/GaN HEMT, respectively. Both the threshold voltage V T and g m max of the dielectric/AlGaN/GaN HEMT are strongly dielectric-constant-dependent. Our results suggest that it is promising to significantly improve the performance of the AlGaN/GaN HEMT by introducing the high-κ organic dielectric. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. A high performance ceria based interdiffusion barrier layer prepared by spin-coating

    Plonczak, Pawel; Joost, Mario; Hjelm, Johan

    2011-01-01

    A multiple spin-coating deposition procedure of Ce0.9Gd0.1O1.95 (CGO) for application in solid oxide fuel cells (SOFCs) was developed. The thin and dense CGO layer can be employed as a barrier layer between yttria stabilised zirconia (YSZ) electrolyte and a (La, Sr)(Co, Fe)O3 based cathode....... The decomposition of the polymer precursor used in the spin-coating process was studied. The depositions were performed on anode supported half cells. By controlling the sintering temperature between each spin-coating process, dense and crack-free CGO films with a thickness of approximately 1 μm were obtained....... The successive steps of dense layer production was investigated by scanning electron microscopy. X-ray diffraction was employed to monitor the crystal structure of the CGO layer sintered at different temperatures. The described spin coated barrier layer was evaluated using an anode supported cell...

  7. A Model of High-Frequency Self-Mixing in Double-Barrier Rectifier

    Palma, Fabrizio; Rao, R.

    2018-03-01

    In this paper, a new model of the frequency dependence of the double-barrier THz rectifier is presented. The new structure is of interest because it can be realized by CMOS image sensor technology. Its application in a complex field such as that of THz receivers requires the availability of an analytical model, which is reliable and able to highlight the dependence on the parameters of the physical structure. The model is based on the hydrodynamic semiconductor equations, solved in the small signal approximation. The model depicts the mechanisms of the THz modulation of the charge in the depleted regions of the double-barrier device and explains the self-mixing process, the frequency dependence, and the detection capability of the structure. The model thus substantially improves the analytical models of the THz rectification available in literature, mainly based on lamped equivalent circuits.

  8. Achieving high field-effect mobility in amorphous indium-gallium-zinc oxide by capping a strong reduction layer.

    Zan, Hsiao-Wen; Yeh, Chun-Cheng; Meng, Hsin-Fei; Tsai, Chuang-Chuang; Chen, Liang-Hao

    2012-07-10

    An effective approach to reduce defects and increase electron mobility in a-IGZO thin-film transistors (a-IGZO TFTs) is introduced. A strong reduction layer, calcium, is capped onto the back interface of a-IGZO TFT. After calcium capping, the effective electron mobility of a-IGZO TFT increases from 12 cm(2) V(-1) s(-1) to 160 cm(2) V(-1) s(-1). This high mobility is a new record, which implies that the proposed defect reduction effect is key to improve electron transport in oxide semiconductor materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Tunable Schottky barrier and high responsivity in graphene/Si-nanotip optoelectronic device

    Di Bartolomeo, Antonio; Giubileo, Filippo; Luongo, Giuseppe; Iemmo, Laura; Martucciello, Nadia; Niu, Gang; Fraschke, Mirko; Skibitzki, Oliver; Schroeder, Thomas; Lupina, Grzegorz

    2017-03-01

    We demonstrate tunable Schottky barrier height and record photo-responsivity in a new-concept device made of a single-layer CVD graphene transferred onto a matrix of nanotips patterned on n-type Si wafer. The original layout, where nano-sized graphene/Si heterojunctions alternate to graphene areas exposed to the electric field of the Si substrate, which acts both as diode cathode and transistor gate, results in a two-terminal barristor with single-bias control of the Schottky barrier. The nanotip patterning favors light absorption, and the enhancement of the electric field at the tip apex improves photo-charge separation and enables internal gain by impact ionization. These features render the device a photodetector with responsivity (3 {{A}} {{{W}}}-1 for white LED light at 3 {{mW}} {{{cm}}}-2 intensity) almost an order of magnitude higher than commercial photodiodes. We extensively characterize the voltage and the temperature dependence of the device parameters, and prove that the multi-junction approach does not add extra-inhomogeneity to the Schottky barrier height distribution. We also introduce a new phenomenological graphene/semiconductor diode equation, which well describes the experimental I-V characteristics both in forward and reverse bias.

  10. Simulation of crash tests for high impact levels of a new bridge safety barrier

    Drozda, Jiří; Rotter, Tomáš

    2017-09-01

    The purpose is to show the opportunity of a non-linear dynamic impact simulation and to explain the possibility of using finite element method (FEM) for developing new designs of safety barriers. The main challenge is to determine the means to create and validate the finite element (FE) model. The results of accurate impact simulations can help to reduce necessary costs for developing of a new safety barrier. The introductory part deals with the creation of the FE model, which includes the newly-designed safety barrier and focuses on the application of an experimental modal analysis (EMA). The FE model has been created in ANSYS Workbench and is formed from shell and solid elements. The experimental modal analysis, which was performed on a real pattern, was employed for measuring the modal frequencies and shapes. After performing the EMA, the FE mesh was calibrated after comparing the measured modal frequencies with the calculated ones. The last part describes the process of the numerical non-linear dynamic impact simulation in LS-DYNA. This simulation was validated after comparing the measured ASI index with the calculated ones. The aim of the study is to improve professional public knowledge about dynamic non-linear impact simulations. This should ideally lead to safer, more accurate and profitable designs.

  11. Investigation of the High Mobility IGZO Thin Films by Using Co-Sputtering Method

    Hsu, Chao-Ming; Tzou, Wen-Cheng; Yang, Cheng-Fu; Liou, Yu-Jhen

    2015-01-01

    High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO) ceramic and In2O3 ceramic at the same time. The deposition power of pure In2O3 ceramic target was fixed at 100 W and the deposition power of GZO ceramic target was changed from 80 W to 140 W. We chose to investigate the deposition power of GZO ceramic target on the properties of IGZO thin films. From the SEM observations, all of the deposited IGZO thin films showed a very smooth and featureless surface. From the measurements of XRD patterns, only the amorphous structure was observed. We aimed to show that the deposition power of GZO ceramic target had large effect on the Eg values, Hall mobility, carrier concentration, and resistivity of IGZO thin films. Secondary ion mass spectrometry (SIMS) analysis in the thicknesses’ profile of IGZO thin films found that In and Ga elements were uniform distribution and Zn element were non-uniform distribution. The SIMS analysis results also showed the concentrations of Ga and Zn elements increased and the concentrations of In element was almost unchanged with increasing deposition power.

  12. Investigation of the High Mobility IGZO Thin Films by Using Co-Sputtering Method

    Chao-Ming Hsu

    2015-05-01

    Full Text Available High transmittance ratio in visible range, low resistivity, and high mobility of IGZO thin films were prepared at room temperature for 30 min by co-sputtering of Zn2Ga2O5 (Ga2O3 + 2 ZnO, GZO ceramic and In2O3 ceramic at the same time. The deposition power of pure In2O3 ceramic target was fixed at 100 W and the deposition power of GZO ceramic target was changed from 80 W to 140 W. We chose to investigate the deposition power of GZO ceramic target on the properties of IGZO thin films. From the SEM observations, all of the deposited IGZO thin films showed a very smooth and featureless surface. From the measurements of XRD patterns, only the amorphous structure was observed. We aimed to show that the deposition power of GZO ceramic target had large effect on the Eg values, Hall mobility, carrier concentration, and resistivity of IGZO thin films. Secondary ion mass spectrometry (SIMS analysis in the thicknesses’ profile of IGZO thin films found that In and Ga elements were uniform distribution and Zn element were non-uniform distribution. The SIMS analysis results also showed the concentrations of Ga and Zn elements increased and the concentrations of In element was almost unchanged with increasing deposition power.

  13. Phosphorene: an unexplored 2D semiconductor with a high hole mobility.

    Liu, Han; Neal, Adam T; Zhu, Zhen; Luo, Zhe; Xu, Xianfan; Tománek, David; Ye, Peide D

    2014-04-22

    We introduce the 2D counterpart of layered black phosphorus, which we call phosphorene, as an unexplored p-type semiconducting material. Same as graphene and MoS2, single-layer phosphorene is flexible and can be mechanically exfoliated. We find phosphorene to be stable and, unlike graphene, to have an inherent, direct, and appreciable band gap. Our ab initio calculations indicate that the band gap is direct, depends on the number of layers and the in-layer strain, and is significantly larger than the bulk value of 0.31-0.36 eV. The observed photoluminescence peak of single-layer phosphorene in the visible optical range confirms that the band gap is larger than that of the bulk system. Our transport studies indicate a hole mobility that reflects the structural anisotropy of phosphorene and complements n-type MoS2. At room temperature, our few-layer phosphorene field-effect transistors with 1.0 μm channel length display a high on-current of 194 mA/mm, a high hole field-effect mobility of 286 cm(2)/V·s, and an on/off ratio of up to 10(4). We demonstrate the possibility of phosphorene integration by constructing a 2D CMOS inverter consisting of phosphorene PMOS and MoS2 NMOS transistors.

  14. Achieving high mobility ZnO : Al at very high growth rates by dc filtered cathodic arc deposition

    Mendelsberg, R J; Lim, S H N; Wallig, J; Anders, A; Zhu, Y K; Milliron, D J

    2011-01-01

    Achieving a high growth rate is paramount for making large-area transparent conducting oxide coatings at a low cost. Unfortunately, the quality of thin films grown by most techniques degrades as the growth rate increases. Filtered dc cathodic arc is a lesser known technique which produces a stream of highly ionized plasma, in stark contrast to the neutral atoms produced by standard sputter sources. Ions bring a large amount of potential energy to the growing surface which is in the form of heat, not momentum. By minimizing the distance from cathode to substrate, the high ion flux gives a very high effective growth temperature near the film surface without causing damage from bombardment. The high surface temperature is a direct consequence of the high growth rate and allows for high-quality crystal growth. Using this technique, 500-1300 nm thick and highly transparent ZnO : Al films were grown on glass at rates exceeding 250 nm min -1 while maintaining resistivity below 5 x 10 -4 Ω cm with electron mobility as high as 60 cm 2 V -1 s -1 . (fast track communication)

  15. Patient-Facing Mobile Apps to Treat High-Need, High-Cost Populations: A Scoping Review.

    Singh, Karandeep; Drouin, Kaitlin; Newmark, Lisa P; Filkins, Malina; Silvers, Elizabeth; Bain, Paul A; Zulman, Donna M; Lee, Jae-Ho; Rozenblum, Ronen; Pabo, Erika; Landman, Adam; Klinger, Elissa V; Bates, David W

    2016-12-19

    Self-management is essential to caring for high-need, high-cost (HNHC) populations. Advances in mobile phone technology coupled with increased availability and adoption of health-focused mobile apps have made self-management more achievable, but the extent and quality of the literature supporting their use is not well defined. The purpose of this review was to assess the breadth, quality, bias, and types of outcomes measured in the literature supporting the use of apps targeting HNHC populations. Data sources included articles in PubMed and MEDLINE (National Center for Biotechnology Information), EMBASE (Elsevier), the Cochrane Central Register of Controlled Trials (EBSCO), Web of Science (Thomson Reuters), and the NTIS (National Technical Information Service) Bibliographic Database (EBSCO) published since 2008. We selected studies involving use of patient-facing iOS or Android mobile health apps. Extraction was performed by 1 reviewer; 40 randomly selected articles were evaluated by 2 reviewers to assess agreement. Our final analysis included 175 studies. The populations most commonly targeted by apps included patients with obesity, physical handicaps, diabetes, older age, and dementia. Only 30.3% (53/175) of the apps studied in the reviewed literature were identifiable and available to the public through app stores. Many of the studies were cross-sectional analyses (42.9%, 75/175), small (median number of participants=31, interquartile range 11.0-207.2, maximum 11,690), or performed by an app's developers (61.1%, 107/175). Of the 175 studies, only 36 (20.6%, 36/175) studies evaluated a clinical outcome. Most apps described in the literature could not be located on the iOS or Android app stores, and existing research does not robustly evaluate the potential of mobile apps. Whereas apps may be useful in patients with chronic conditions, data do not support this yet. Although we had 2-3 reviewers to screen and assess abstract eligibility, only 1 reviewer abstracted

  16. Barriers to the future

    Massey, C T

    1986-09-01

    Opportunities for the British coal industry seem vast yet there are still barriers to progress. Seven areas are identified and discussed: mining mobility (for example, longwall mining systems are rigid and inflexible compared with American stall and pillar working); mine structure (many mines are more suitable to pit ponies than to large pieces of equipment); financial barriers (Government requires the industry to break even in 1987/88); personnel barriers (less specialization, better use of skills); safety barriers (increased use of remote control, ergonomics and robotics to protect workers); microelectronic management (nationalization has cushioned management from the market place; there is a need for a more multidisciplinary approach to the industry); and legal barriers (most legislation in the past has been in response to accidents; legislation external to the industry but affecting it is more fundamental).

  17. AN ANALYSIS OF THE THERMAL AND MECHANICAL BEHAVIOR OF ENGINEERED BARRIERS IN A HIGH-LEVEL RADIOACTIVE WASTE REPOSITORY

    S. KWON

    2013-02-01

    Full Text Available Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high-level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  18. An analysis of the thermal and mechanical behavior of engineered barriers in a high-level radioactive waste repository

    Kwon, S.; Cho, W. J.; Lee, J. O.

    2013-01-01

    Adequate design of engineered barriers, including canister, buffer and backfill, is important for the safe disposal of high level radioactive waste. Three-dimensional computer simulations were carried out under different condition to examine the thermal and mechanical behavior of engineered barriers and rock mass. The research looked at five areas of importance, the effect of the swelling pressure, water content of buffer, density of compacted bentonite, emplacement type and the selection of failure criteria. The results highlighted the need to consider tensile stress in the outer shell of a canister due to thermal expansion of the canister and the swelling pressure from the buffer for a more reliable design of an underground repository system. In addition, an adequate failure criterion should be used for the buffer and backfill.

  19. General factors that affects the increase of population mobility and principles of optimization of high-speed passenger transportations

    Momot, A.

    2014-01-01

    Purpose. Analyze the main factors that influence the increased mobility of the population in the transport market of Ukraine. Methods. The article uses an improved method of determining the optimal areas of high-speed passenger trains and determines the value of rational transportation of passengers in different directions of speed traffic, as well as the method of marginal income. Results. In this article we analyzed seven major factors that influence the increased mobility of the population...

  20. Mobile Phone Use in a Pennsylvania Public High School: Does Policy Inform Practice?

    Thackara, Susan Tomchak

    2014-01-01

    Though many American educators embrace technology in classrooms, administrators can create policies that inhibit technology such as mobile phone use in classrooms or on district property. These policies range from restrictive with no mobile phone use permitted, to liberal in which unrestricted use of mobile phones is allowed. The purpose of this…

  1. Hemoadsorption of high-mobility-group box 1 using a porous polymethylmethacrylate fiber in a swine acute liver failure model.

    Amemiya, Ryusuke; Shinoda, Masahiro; Yamada, Masayuki; Ueno, Yoshiyuki; Shimada, Kaoru; Fujieda, Hiroaki; Yagi, Hiroshi; Mizota, Takamasa; Nishiyama, Ryo; Oshima, Go; Yamada, Shingo; Matsubara, Kentaro; Abe, Yuta; Hibi, Taizo; Kitago, Minoru; Obara, Hideaki; Itano, Osamu; Kitagawa, Yuko

    2018-04-01

    High-mobility-group box chromosomal protein 1 has been identified as an important mediator of various kinds of acute and chronic inflammation. In this study, we aimed to develop a column that effectively adsorbs high-mobility-group box chromosomal protein 1 by altering the pore size of the fiber. First, we produced three types of porous polymethylmethacrylate fiber by altering the concentration of polymethylmethacrylate dissolved in dimethylsulfoxide. We then selected a fiber based on the results of an in vitro incubation test of high-mobility-group box chromosomal protein 1 adsorption. Using the selected fiber, we constructed a new column and tested its high-mobility-group box chromosomal protein 1 adsorption capacity during 4-h extracorporeal hemoperfusion in a swine acute liver failure model. Electron microscope observation showed that the three types of fibers had different pore sizes on the surface and in cross section, which were dependent on the concentration of polymethylmethacrylate. In the in vitro incubation test, fiber with moderate-sized pores demonstrated the highest adsorption capacity. In the in vivo hemoperfusion study, the ratio of the high-mobility-group box chromosomal protein 1 concentration at the outlet versus the inlet of the column was significantly lower with the new column than with the control column during 4-h extracorporeal hemoperfusion. The normalized plasma level of high-mobility-group box chromosomal protein 1 at 12 h after the completion of hemoperfusion was significantly lower with the new column than with the control column. The newly developed polymethylmethacrylate column adsorbs high-mobility-group box chromosomal protein 1 during hemoperfusion in swine ALF model.

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

    Mohammad Javad Sharifi

    2009-01-01

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

  3. High-Mobility, Ultrathin Organic Semiconducting Films Realized by Surface-Mediated Crystallization.

    Vladimirov, I; Kellermeier, M; Geßner, T; Molla, Zarah; Grigorian, S; Pietsch, U; Schaffroth, L S; Kühn, M; May, F; Weitz, R T

    2018-01-10

    The functionality of common organic semiconductor materials is determined by their chemical structure and crystal modification. While the former can be fine-tuned via synthesis, a priori control over the crystal structure has remained elusive. We show that the surface tension is the main driver for the plate-like crystallization of a novel small organic molecule n-type semiconductor at the liquid-air interface. This interface provides an ideal environment for the growth of millimeter-sized semiconductor platelets that are only few nanometers thick and thus highly attractive for application in transistors. On the basis of the novel high-performance perylene diimide, we show in as-grown, only 3 nm thin crystals electron mobilities of above 4 cm 2 /(V s) and excellent bias stress stability. We suggest that the established systematics on solvent parameters can provide the basis of a general framework for a more deterministic crystallization of other small molecules.

  4. Advertising on mobile applications

    Sobolevsky, Alexandr

    2015-01-01

    The article analyzes the new method of mobile advertising. Advertising in mobile applications - a subspecies of mobile marketing, where advertising is distributed using mobile phones and smartphones. Ad placement is going on inside of applications and games for smartphones. It has a high potential due to the large number of mobile phone users (over 6.5 billion in 2013).

  5. Does a Mobile Phone Depression-Screening App Motivate Mobile Phone Users With High Depressive Symptoms to Seek a Health Care Professional's Help?

    BinDhim, Nasser F; Alanazi, Eman M; Aljadhey, Hisham; Basyouni, Mada H; Kowalski, Stefan R; Pont, Lisa G; Shaman, Ahmed M; Trevena, Lyndal; Alhawassi, Tariq M

    2016-06-27

    The objective of disease screening is to encourage high-risk subjects to seek health care diagnosis and treatment. Mobile phone apps can effectively screen mental health conditions, including depression. However, it is not known how effective such screening methods are in motivating users to discuss the obtained results of such apps with health care professionals. Does a mobile phone depression-screening app motivate users with high depressive symptoms to seek health care professional advice? This study aimed to address this question. This was a single-cohort, prospective, observational study of a free mobile phone depression app developed in English and released on Apple's App Store. Apple App Store users (aged 18 or above) in 5 countries, that is, Australia, Canada, New Zealand (NZ), the United Kingdom (UK), and the United States (US), were recruited directly via the app's download page. The participants then completed the Patient Health Questionnaire (PHQ-9), and their depression screening score was displayed to them. If their score was 11 or above and they had never been diagnosed with depression before, they were advised to take their results to their health care professional. They were to follow up after 1 month. A group of 2538 participants from the 5 countries completed PHQ-9 depression screening with the app. Of them, 322 participants were found to have high depressive symptoms and had never been diagnosed with depression, and received advice to discuss their results with health care professionals. About 74% of those completed the follow-up; approximately 38% of these self-reported consulting their health care professionals about their depression score. Only positive attitude toward depression as a real disease was associated with increased follow-up response rate (odds ratio (OR) 3.2, CI 1.38-8.29). A mobile phone depression-screening app motivated some users to seek a depression diagnosis. However, further study should investigate how other app users use

  6. Measurement of negative ion mobility in O2 at high pressures using a point plate gap as an ion detector

    Okuyama, Y; Kimura, T; Suzuki, S; Itoh, H

    2012-01-01

    This paper describes the experimental results for negative ion mobility in O 2 at 0.5-2.0 atm. The ion mobility is observed using a high-pressure ion drift tube with a positive corona gap (Geiger counter), which is constructed from a point plate gap and acts as a negative ion detector. The variation of waveforms in the burst pulse is observed by varying the voltage applied to the ion detector to find the optimum voltage that must be applied across the ion detector in O 2 . This is investigated carefully to ensure the precise determination of mobility. The distortion of the electric field near the mesh electrode, which operates as the cathode of the ion detector and as the anode of the ion drift gap, is then examined to determine the optimum applied voltage to suppress its effect on the measurement of mobility. The mobility is subsequently measured at a reduced electric field intensity of 2.83 × 10 -3 to 2.83. The observed mobility of 2.31 ± 0.03 cm 2 V -1 s -1 in O 2 is concluded to be that of O 2 - . This value is also obtained in experiments over a wide range of gas pressures (0.5-2.0 atm) and drift lengths (1.00-9.00 cm). The mobilities of O 3 - and O - are also obtained experimentally. (paper)

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

    Nassar, Joanna M.

    2014-05-01

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

  8. In-plane heterostructures of Sb/Bi with high carrier mobility

    Zhao, Pei; Wei, Wei; Sun, Qilong; Yu, Lin; Huang, Baibiao; Dai, Ying

    2017-06-01

    In-plane two-dimensional (2D) heterostructures have been attracting public attention due to their distinctive properties. However, the pristine materials that can form in-plane heterostructures are reported only for graphene, hexagonal BN, transition-metal dichalcogenides. It will be of great significance to explore more suitable 2D materials for constructing such ingenious heterostructures. Here, we demonstrate two types of novel seamless in-plane heterostructures combined by pristine Sb and Bi monolayers by means of first-principle approach based on density functional theory. Our results indicate that external strain can serve as an effective strategy for bandgap engineering, and the transition from semiconductor to metal occurs when a compressive strain of -8% is applied. In addition, the designed heterostructures possess direct band gaps with high carrier mobility (˜4000 cm2 V-1 s-1). And the mobility of electrons and holes have huge disparity along the direction perpendicular to the interface of Sb/Bi in-plane heterostructures. It is favorable for carriers to separate spatially. Finally, we find that the band edge positions of Sb/Bi in-plane heterostructures can meet the reduction potential of hydrogen generation in photocatalysis. Our results not only offer alternative materials to construct versatile in-plane heterostructures, but also highlight the applications of 2D in-plane heterostructures in diverse nanodevices and photocatalysis.

  9. Solution-processable ambipolar diketopyrrolopyrrole-selenophene polymer with unprecedentedly high hole and electron mobilities.

    Lee, Junghoon; Han, A-Reum; Kim, Jonggi; Kim, Yiho; Oh, Joon Hak; Yang, Changduk

    2012-12-26

    There is a fast-growing demand for polymer-based ambipolar thin-film transistors (TFTs), in which both n-type and p-type transistor operations are realized in a single layer, while maintaining simplicity in processing. Research progress toward this end is essentially fueled by molecular engineering of the conjugated backbones of the polymers and the development of process architectures for device fabrication, which has recently led to hole and electron mobilities of more than 1.0 cm(2) V(-1) s(-1). However, ambipolar polymers with even higher performance are still required. By taking into account both the conjugated backbone and side chains of the polymer component, we have developed a dithienyl-diketopyrrolopyrrole (TDPP) and selenophene containing polymer with hybrid siloxane-solubilizing groups (PTDPPSe-Si). A synergistic combination of rational polymer backbone design, side-chain dynamics, and solution processing affords an enormous boost in ambipolar TFT performance, resulting in unprecedentedly high hole and electron mobilities of 3.97 and 2.20 cm(2) V(-1) s(-1), respectively.

  10. Fabrication and characterization of high-mobility solution-based chalcogenide thin-film transistors

    Mejia, Israel I.; Salas Villaseñ or, Ana L.; Cha, Dong Kyu; Alshareef, Husam N.; Gnade, Bruce E.; Quevedo-Ló pez, Manuel Angel Quevedo

    2013-01-01

    We report device and material considerations for the fabrication of high-mobility thin-film transistors (TFTs) compatible with large-area and inexpensive processes. In particular, this paper reports photolithographically defined n-type TFTs (n-TFTs) based on cadmium sulfide (CdS) films deposited using solution-based techniques. The integration process consists of four mask levels with a maximum processing temperature of 100 °C. The TFT performance was analyzed in terms of the CdS semiconductor thickness and as a function of postdeposition annealing in a reducing ambient. The IonI off ratios are ∼107 with field-effect mobilities of ∼5.3 and ∼4.7cm2V̇s for Al and Au source-drain contacts, respectively, using 70 nm of CdS. Transmission electron microscopy and electron energy loss spectroscopy were used to analyze the CdS-metal interfaces. © 1963-2012 IEEE.

  11. High Purity Germanium Detector as part of Health Canada's Mobile Nuclear Laboratory

    Stocki, Trevor J.; Bouchard, Claude; Rollings, John; Boudreau, Marc-Oliver; McCutcheon- Wickham, Rory; Bergman, Lauren [Radiation Protection Bureau, Health Canada, AL6302D, 775 Brookfield Road, Ottawa, K1A 0K9 (Canada)

    2014-07-01

    In the event of a nuclear emergency on Canadian soil, Health Canada has designed and equipped two Mobile Nuclear Labs (MNLs) which can be deployed near a radiological accident site to provide radiological measurement capabilities. These measurements would help public authorities to make informed decisions for radiation protection recommendations. One of the MNLs has been outfitted with a High Purity Germanium (HPGe) detector within a lead castle, which can be used for identification as well as quantification of gamma emitting radioisotopes in contaminated soil, water, and other samples. By spring 2014, Health Canada's second MNL will be equipped with a similar detector to increase sample analysis capacity and also provide redundancy if one of the detectors requires maintenance. The Mobile Nuclear Lab (MNL) with the HPGe detector has been successfully deployed in the field for various exercises. One of these field exercises was a dirty bomb scenario where an unknown radioisotope required identification. A second exercise was an inter-comparison between the measurements of spiked soil and water samples, by two field teams and a certified laboratory. A third exercise was the deployment of the MNL as part of a full scale nuclear exercise simulating an emergency at a Canadian nuclear power plant. The lessons learned from these experiences will be discussed. (authors)

  12. Environmental stability of high-mobility indium-oxide based transparent electrodes

    Thanaporn Tohsophon

    2015-11-01

    Full Text Available Large-scale deployment of a wide range of optoelectronic devices, including solar cells, critically depends on the long-term stability of their front electrodes. Here, we investigate the performance of Sn-doped In2O3 (ITO, H-doped In2O3 (IO:H, and Zn-doped In2O3 (IZO electrodes under damp heat (DH conditions (85 °C, 85% relative humidity. ITO, IO:H capped with ITO, and IZO show high stability with only 3%, 9%, and 13% sheet resistance (Rs degradation after 1000 h of DH, respectively. For uncapped IO:H, we find a 75% Rs degradation, due to losses in electron Hall mobility (μHall. We propose that this degradation results from chemisorbed OH- or H2O-related species in the film, which is confirmed by thermal desorption spectroscopy and x-ray photoelectron spectroscopy. While μHall strongly degrades during DH, the optical mobility (μoptical remains unchanged, indicating that the degradation mainly occurs at grain boundaries.

  13. Rehabilitation of a house with high radon level, using a ground ventilation system with double barrier

    Bonnefous, Y.C.; Richon, P.; Arnautou, J.C.; Sabroux, J.C.

    1995-01-01

    A ground ventilation system has been designed and implemented in a town hall in Brittany. Radon concentration in the heating unit room of this building has been reduced from 10000 Bq/m 3 to less than 200 Bq/m 3 by the means of a depressurization system using a 32 W fan, which blows air into a permeable gravel layer intercalated between two radon barrier mylar films. Results show that passive systems should be applicable; for new buildings, very low energy consumption systems with 10 W fans, are easily implemented if designed before construction

  14. Structural-morphological variations in pseudo-barrier films of anode aluminium oxide under irradiation with high-energy particles

    Chernykh, M.A.; Belov, V.T.

    1988-01-01

    Comparative study of structural-morphological variations under electron beam effect in pseudo-barrier films of anode aluminium oxide, obtained in seven different solutions and proton or X-rays pre-irradiated to determine structure peculiarities of anode aluminium oxides, is presented. Such study is a matter of interest from the solid-phase transformation theory point of view and for anode aluminium films application under radiation. Stability increase of pseudo-barrier films of anode aluminium oxide to the effect of UEhMV-100 K microscope electron beam at standard modes of operation (75 kV) due to proton or X-rays irradiation is found. Difference in structural-monorphological variations obtained in different solutions of anode aluminium films under high-energy particles irradiation is determined. Strucural-phase microinhomogeneity of amorphous pseudo-barrier films of anode aluminium oxide and its influence on solid-phase transformations character under electron bean of maximal intensity are detected

  15. Identification, Attribution, and Quantification of Highly Heterogeneous Methane Sources Using a Mobile Stable Isotope Analyzer

    Crosson, E.; Rella, C.; Cunningham, K.

    2012-04-01

    Despite methane's importance as a potent greenhouse gas second only to carbon dioxide in the magnitude of its contribution to global warming, natural contributions to the overall methane budget are only poorly understood. A big contributor to this gap in knowledge is the highly spatially and temporally heterogeneous nature of most natural (and for that matter anthropogenic) methane sources. This high degree of heterogeneity, where the methane emission rates can vary over many orders of magnitude on a spatial scale of meters or even centimeters, and over a temporal scale of minutes or even seconds, means that traditional methods of emissions flux estimation, such as flux chambers or eddy-covariance, are difficult or impossible to apply. In this paper we present new measurement methods that are capable of detecting, attributing, and quantifying emissions from highly heterogeneous sources. These methods take full advantage of the new class of methane concentration and stable isotope analyzers that are capable of laboratory-quality analysis from a mobile field platform in real time. In this paper we present field measurements demonstrating the real-time detection of methane 'hot spots,' attribution of the methane to a source process via real-time stable isotope analysis, and quantification of the emissions flux using mobile concentration measurements of the horizontal and vertical atmospheric dispersion, combined with atmospheric transport calculations. Although these techniques are applicable to both anthropogenic and natural methane sources, in this initial work we focus primarily on landfills and fugitive emissions from natural gas distribution, as these sources are better characterized, and because they provide a more reliable and stable source of methane for quantifying the measurement uncertainty inherent in the different methods. Implications of these new technologies and techniques are explored for the quantification of natural methane sources in a variety of

  16. Mobile Measurements of Methane Using High-Speed Open-Path Technology

    Burba, G. G.; Anderson, T.; Ediger, K.; von Fischer, J.; Gioli, B.; Ham, J. M.; Hupp, J. R.; Kohnert, K.; Levy, P. E.; Polidori, A.; Pikelnaya, O.; Price, E.; Sachs, T.; Serafimovich, A.; Zondlo, M. A.; Zulueta, R. C.

    2016-12-01

    Methane plays a critical role in the radiation balance, chemistry of the atmosphere, and air quality. The major anthropogenic sources of CH4 include oil and gas development sites, natural gas distribution networks, landfill emissions, and agricultural production. The majority of oil and gas and urban CH4 emission occurs via variable-rate point sources or diffused spots in topographically challenging terrains (e.g., street tunnels, elevated locations at water treatment plants, vents, etc.). Locating and measuring such CH4 emissions is challenging when using traditional micrometeorological techniques, and requires development of novel approaches. Landfill CH4 emissions traditionally assessed at monthly or longer time intervals are subject to large uncertainties because of the snapshot nature of the measurements and the barometric pumping phenomenon. The majority of agricultural and natural CH4 production occurs in areas with little infrastructure or easily available grid power (e.g., rice fields, arctic and boreal wetlands, tropical mangroves, etc.). A lightweight, high-speed, high-resolution, open-path technology was recently developed for eddy covariance measurements of CH4 flux, with power consumption 30-150 times below other available technologies. It was designed to run on solar panels or a small generator and be placed in the middle of the methane-producing ecosystem without a need for grid power. Lately, this instrumentation has been utilized increasingly more frequently outside of the traditional use on stationary flux towers. These novel approaches include measurements from various moving platforms, such as cars, aircraft, and ships. Projects included mapping of concentrations and vertical profiles, leak detection and quantification, mobile emission detection from natural gas-powered cars, soil CH4 flux surveys, etc. This presentation will describe key projects utilizing the novel lightweight low-power high-resolution open-path technology, and will highlight

  17. Nanoscale investigation of AlGaN/GaN-on-Si high electron mobility transistors.

    Fontserè, A; Pérez-Tomás, A; Placidi, M; Llobet, J; Baron, N; Chenot, S; Cordier, Y; Moreno, J C; Jennings, M R; Gammon, P M; Fisher, C A; Iglesias, V; Porti, M; Bayerl, A; Lanza, M; Nafría, M

    2012-10-05

    AlGaN/GaN HEMTs are devices which are strongly influenced by surface properties such as donor states, roughness or any kind of inhomogeneity. The electron gas is only a few nanometers away from the surface and the transistor forward and reverse currents are considerably affected by any variation of surface property within the atomic scale. Consequently, we have used the technique known as conductive AFM (CAFM) to perform electrical characterization at the nanoscale. The AlGaN/GaN HEMT ohmic (drain and source) and Schottky (gate) contacts were investigated by the CAFM technique. The estimated area of these highly conductive pillars (each of them of approximately 20-50 nm radius) represents around 5% of the total contact area. Analogously, the reverse leakage of the gate Schottky contact at the nanoscale seems to correlate somehow with the topography of the narrow AlGaN barrier regions producing larger currents.

  18. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Darthout, Émilien; Gitzhofer, François

    2017-12-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  19. High-mobility germanium p-MOSFETs by using HCl and (NH4)2S surface passivation

    Xue Bai-Qing; Wang Sheng-Kai; Han Le; Chang Hu-Dong; Sun Bing; Zhao Wei; Liu Hong-Gang

    2013-01-01

    To achieve a high-quality high-κ/Ge interfaces for high hole mobility Ge p-MOSFET applications, a simple chemical cleaning and surface passivation scheme is introduced, and Ge p-MOSFETs with effective channel hole mobility up to 665 cm 2 /V·s are demonstrated on a Ge (111) substrate. Moreover, a physical model is proposed to explain the dipole layer formation at the metal—oxide—semiconductor (MOS) interface by analyzing the electrical characteristics of HCl- and (NH 4 ) 2 S-passivated samples. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Double pulse doped InGaAs/AlGaAs/GaAs pseudomorphic high-electron-mobility transistor heterostructures

    Egorov, A. Yu.; Gladyshev, A. G.; Nikitina, E. V.; Denisov, D. V.; Polyakov, N. K.; Pirogov, E. V.; Gorbazevich, A. A.

    2010-01-01

    Double pulse doped (δ-doped) InGaAs/AlGaAs/GaAs pseudomorphic high-electron-mobility transistor (HEMT) heterostructures were grown by molecular-beam epitaxy using a multiwafer technological system. The room-temperature electron mobility was determined by the Hall method as 6550 and 6000 cm 2 /(V s) at sheet electron densities of 3.00 x 10 12 and 3.36 x 10 12 cm -2 , respectively. HEMT heterostructures fabricated in a single process feature high uniformity of structural and electrical characteristics over the entire area of wafers 76.2 mm in diameter and high reproducibility of characteristics from process to process.

  1. [Mobile hospital -real time mobile telehealthcare system with ultrasound and CT van using high-speed satellite communication-].

    Takizawa, Masaomi; Miyashita, Toyohisa; Murase, Sumio; Kanda, Hirohito; Karaki, Yoshiaki; Yagi, Kazuo; Ohue, Toru

    2003-01-01

    A real-time telescreening system is developed to detect early diseases for rural area residents using two types of mobile vans with a portable satellite station. The system consists of a satellite communication system with 1.5Mbps of the JCSAT-1B satellite, a spiral CT van, an ultrasound imaging van with two video conference system, a DICOM server and a multicast communication unit. The video image and examination image data are transmitted from the van to hospitals and the university simultaneously. Physician in the hospital observes and interprets exam images from the van and watches the video images of the position of ultrasound transducer on screenee in the van. After the observation images, physician explains a results of the examination by the video conference system. Seventy lung CT screening and 203 ultrasound screening were done from March to June 2002. The trial of this real time screening suggested that rural residents are given better healthcare without visit to the hospital. And it will open the gateway to reduce the medical cost and medical divide between city area and rural area.

  2. Mobile Learning in Medical Education: Review.

    Walsh, Kieran

    2015-10-01

    In the past several years, mobile learning made rapid inroads into the provision of medical education. There are significant advantages associated with mobile learning. These include high access, low cost, more situated and contextual learning, convenience for the learner, continuous communication and interaction between learner and tutor and between learner and other learners, and the ability to self-assess themselves while learning. Like any other form of medical pedagogy, mobile learning has its downsides. Disadvantages of mobile learning include: inadequate technology, a risk of distraction from learning by using a device that can be used for multiple purposes, and the potential for breakdown in barriers between personal usage of the mobile device and professional or educational use. Despite these caveats, there is no question but that mobile learning offers much potential. In the future, it is likely that the strategy of mobile first, whereby providers of e-learning think of the user experience on a mobile first, will result in learners who increasingly expect that all e-learning provision will work seamlessly on a mobile device.

  3. An intelligent detection method for high-field asymmetric waveform ion mobility spectrometry.

    Li, Yue; Yu, Jianwen; Ruan, Zhiming; Chen, Chilai; Chen, Ran; Wang, Han; Liu, Youjiang; Wang, Xiaozhi; Li, Shan

    2018-04-01

    In conventional high-field asymmetric waveform ion mobility spectrometry signal acquisition, multi-cycle detection is time consuming and limits somewhat the technique's scope for rapid field detection. In this study, a novel intelligent detection approach has been developed in which a threshold was set on the relative error of α parameters, which can eliminate unnecessary time spent on detection. In this method, two full-spectrum scans were made in advance to obtain the estimated compensation voltage at different dispersion voltages, resulting in a narrowing down of the whole scan area to just the peak area(s) of interest. This intelligent detection method can reduce the detection time to 5-10% of that of the original full-spectrum scan in a single cycle.

  4. Provision of 3G Mobile Services in Sparsely Populated Areas Using High Altitude Platforms

    J. Holis

    2008-04-01

    Full Text Available This paper deals with the application of High Altitude Platforms for the provision of third generation mobile services in sparsely-populated areas or in developing countries. It focuses on the behavior of large cells provided via a multiple HAP deployment and shows the possibilities of using small cells located inside these large cells to serve hot-spot areas. The impact of the different types of HAP antenna masks and their adjustment on cell capacity and the quality of coverage is presented. The main parameter of the antenna radiation pattern under investigation is the power roll-off at the cell edge. Optimal values of this parameter are presented for different scenarios. Simulations of system level parameters were based on an iteration loops approach.

  5. High Mobility Thin Film Transistors Based on Amorphous Indium Zinc Tin Oxide

    Imas Noviyana

    2017-06-01

    Full Text Available Top-contact bottom-gate thin film transistors (TFTs with zinc-rich indium zinc tin oxide (IZTO active layer were prepared at room temperature by radio frequency magnetron sputtering. Sintered ceramic target was prepared and used for deposition from oxide powder mixture having the molar ratio of In2O3:ZnO:SnO2 = 2:5:1. Annealing treatment was carried out for as-deposited films at various temperatures to investigate its effect on TFT performances. It was found that annealing treatment at 350 °C for 30 min in air atmosphere yielded the best result, with the high field effect mobility value of 34 cm2/Vs and the minimum subthreshold swing value of 0.12 V/dec. All IZTO thin films were amorphous, even after annealing treatment of up to 350 °C.

  6. A southern African origin and cryptic structure in the highly mobile plains zebra

    Pedersen, Casper-Emil T; Albrechtsen, Anders; Etter, Paul D.

    2018-01-01

    insights into the past phylogeography of the species. The results identify a southern African location as the most likely source region from which all extant populations expanded around 370,000 years ago. We show evidence for inclusion of the extinct and phenotypically divergent quagga (Equus quagga quagga......The plains zebra (Equus quagga) is an ecologically important species of the African savannah. It is also one of the most numerous and widely distributed ungulates, and six subspecies have been described based on morphological variation. However, the within-species evolutionary processes have been...... difficult to resolve due to its high mobility and a lack of consensus regarding the population structure. We obtained genome-wide DNA polymorphism data from more than 167,000 loci for 59 plains zebras from across the species range, encompassing all recognized extant subspecies, as well as three mountain...

  7. Very high frame rate volumetric integration of depth images on mobile devices.

    Kähler, Olaf; Adrian Prisacariu, Victor; Yuheng Ren, Carl; Sun, Xin; Torr, Philip; Murray, David

    2015-11-01

    Volumetric methods provide efficient, flexible and simple ways of integrating multiple depth images into a full 3D model. They provide dense and photorealistic 3D reconstructions, and parallelised implementations on GPUs achieve real-time performance on modern graphics hardware. To run such methods on mobile devices, providing users with freedom of movement and instantaneous reconstruction feedback, remains challenging however. In this paper we present a range of modifications to existing volumetric integration methods based on voxel block hashing, considerably improving their performance and making them applicable to tablet computer applications. We present (i) optimisations for the basic data structure, and its allocation and integration; (ii) a highly optimised raycasting pipeline; and (iii) extensions to the camera tracker to incorporate IMU data. In total, our system thus achieves frame rates up 47 Hz on a Nvidia Shield Tablet and 910 Hz on a Nvidia GTX Titan XGPU, or even beyond 1.1 kHz without visualisation.

  8. New Mutation Identified in the SRY Gene High Mobility Group (HMG

    Feride İffet Şahin

    2013-06-01

    Full Text Available Mutations in the SRY gene prevent the differentiation of the fetal gonads to testes and cause developing female phenotype, and as a result sex reversal and pure gonadal dysgenesis (Swyer syndrome can be developed. Different types of mutations identified in the SRY gene are responsible for 15% of the gonadal dysgenesis. In this study, we report a new mutation (R132P in the High Mobility Group (HMG region of SRY gene was detected in a patient with primary amenorrhea who has 46,XY karyotype. This mutation leads to replacement of the polar and basic arginine with a nonpolar hydrophobic proline residue at aminoacid 132 in the nuclear localization signal region of the protein. With this case report we want to emphasize the genetic approach to the patients with gonadal dysgenesis. If Y chromosome is detected during cytogenetic analysis, revealing the presence of the SRY gene and identification of mutations in this gene by sequencing analysis is become important in.

  9. Electric field driven plasmon dispersion in AlGaN/GaN high electron mobility transistors

    Tan Ren-Bing; Qin Hua; Zhang Xiao-Yu; Xu Wen

    2013-01-01

    We present a theoretical study on the electric field driven plasmon dispersion of the two-dimensional electron gas (2DEG) in AlGaN/GaN high electron mobility transistors (HEMTs). By introducing a drifted Fermi—Dirac distribution, we calculate the transport properties of the 2DEG in the AlGaN/GaN interface by employing the balance-equation approach based on the Boltzmann equation. Then, the nonequilibrium Fermi—Dirac function is obtained by applying the calculated electron drift velocity and electron temperature. Under random phase approximation (RPA), the electric field driven plasmon dispersion is investigated. The calculated results indicate that the plasmon frequency is dominated by both the electric field E and the angle between wavevector q and electric field E. Importantly, the plasmon frequency could be tuned by the applied source—drain bias voltage besides the gate voltage (change of the electron density)

  10. Tooth enamel oxygen "isoscapes" show a high degree of human mobility in prehistoric Britain.

    Pellegrini, Maura; Pouncett, John; Jay, Mandy; Pearson, Mike Parker; Richards, Michael P

    2016-10-07

    A geostatistical model to predict human skeletal oxygen isotope values (δ 18 O p ) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as 'non-local' to the areas where they were buried (spatial outliers). A marked variation in δ 18 O p is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ 18 O values-a process known to be problematic.

  11. Tooth enamel oxygen “isoscapes” show a high degree of human mobility in prehistoric Britain

    Pellegrini, Maura; Pouncett, John; Jay, Mandy; Pearson, Mike Parker; Richards, Michael P.

    2016-10-01

    A geostatistical model to predict human skeletal oxygen isotope values (δ18Op) in Britain is presented here based on a new dataset of Chalcolithic and Early Bronze Age human teeth. The spatial statistics which underpin this model allow the identification of individuals interpreted as ‘non-local’ to the areas where they were buried (spatial outliers). A marked variation in δ18Op is observed in several areas, including the Stonehenge region, the Peak District, and the Yorkshire Wolds, suggesting a high degree of human mobility. These areas, rich in funerary and ceremonial monuments, may have formed focal points for people, some of whom would have travelled long distances, ultimately being buried there. The dataset and model represent a baseline for future archaeological studies, avoiding the complex conversions from skeletal to water δ18O values-a process known to be problematic.

  12. The role of high mobility group box 1(HMGB1)in the pathogenesis of kidney diseases

    Qingjie Chen; Xiaofeng Guan; Xiaocong Zuo; Jianglin Wang; Wenjun Yin

    2016-01-01

    High mobility group box 1(HMGB1) is a nuclear protein that can bind to DNA and act as a co-factor for gene transcription. When released into extracellular fluid, it plays a proinflammatory role by acting as a damage-associated molecular pattern molecule(DAMP)(also known as an alarmin) to initiate innate immune responses by activating multiple cell surface receptors such as the receptor for advanced glycation end-products(RAGE) and toll-like receptors(TLRs), TLR2, TLR4 or TLR9. This proinflammatory role is now considered to be important in the pathogenesis of a wide range of kidney diseases whether they result from hemodynamic changes, renal tubular epithelial cell apoptosis, kidney tissue fibrosis or inflammation. This review summarizes our current understanding of the role of HMGB1 in kidney diseases and how the HMGB1-mediated signaling pathway may constitute a new strategy for the treatment of kidney diseases.

  13. Polarization sensitive detection of 100 GHz radiation by high mobility field-effect transistors

    Sakowicz, M.; Lusakowski, J.; Karpierz, K.; Grynberg, M.; Knap, W.; Gwarek, W.

    2008-01-01

    Detection of 100 GHz electromagnetic radiation by a GaAs/AlGaAs high electron mobility field-effect transistor was investigated at 300 K as a function of the angle α between the direction of linear polarization of the radiation and the symmetry axis of the transistor. The angular dependence of the detected signal was found to be A 0 cos 2 (α-α 0 )+C with A 0 , α 0 , and C dependent on the electrical polarization of the transistor gate. This dependence is interpreted as due to excitation of two crossed phase-shifted oscillators. A response of the transistor chip (including bonding wires and the substrate) to 100 GHz radiation was numerically simulated. Results of calculations confirmed experimentally observed dependencies and showed that the two oscillators result from an interplay of 100 GHz currents defined by the transistor impedance together with bonding wires and substrate related modes

  14. Botulinum toxin detection using AlGaN /GaN high electron mobility transistors

    Wang, Yu-Lin; Chu, B. H.; Chen, K. H.; Chang, C. Y.; Lele, T. P.; Tseng, Y.; Pearton, S. J.; Ramage, J.; Hooten, D.; Dabiran, A.; Chow, P. P.; Ren, F.

    2008-12-01

    Antibody-functionalized, Au-gated AlGaN /GaN high electron mobility transistors (HEMTs) were used to detect botulinum toxin. The antibody was anchored to the gate area through immobilized thioglycolic acid. The AlGaN /GaN HEMT drain-source current showed a rapid response of less than 5s when the target toxin in a buffer was added to the antibody-immobilized surface. We could detect a range of concentrations from 1to10ng/ml. These results clearly demonstrate the promise of field-deployable electronic biological sensors based on AlGaN /GaN HEMTs for botulinum toxin detection.

  15. Low-voltage high-speed programming gate-all-around floating gate memory cell with tunnel barrier engineering

    Hamzah, Afiq; Ezaila Alias, N.; Ismail, Razali

    2018-06-01

    The aim of this study is to investigate the memory performances of gate-all-around floating gate (GAA-FG) memory cell implementing engineered tunnel barrier concept of variable oxide thickness (VARIOT) of low-k/high-k for several high-k (i.e., Si3N4, Al2O3, HfO2, and ZrO2) with low-k SiO2 using three-dimensional (3D) simulator Silvaco ATLAS. The simulation work is conducted by initially determining the optimized thickness of low-k/high-k barrier-stacked and extracting their Fowler–Nordheim (FN) coefficients. Based on the optimized parameters the device performances of GAA-FG for fast program operation and data retention are assessed using benchmark set by 6 and 8 nm SiO2 tunnel layer respectively. The programming speed has been improved and wide memory window with 30% increment from conventional SiO2 has been obtained using SiO2/Al2O3 tunnel layer due to its thin low-k dielectric thickness. Furthermore, given its high band edges only 1% of charge-loss is expected after 10 years of ‑3.6/3.6 V gate stress.

  16. Toolbox for Urban Mobility Simulation: High Resolution Population Dynamics for Global Cities

    Bhaduri, B. L.; Lu, W.; Liu, C.; Thakur, G.; Karthik, R.

    2015-12-01

    In this rapidly urbanizing world, unprecedented rate of population growth is not only mirrored by increasing demand for energy, food, water, and other natural resources, but has detrimental impacts on environmental and human security. Transportation simulations are frequently used for mobility assessment in urban planning, traffic operation, and emergency management. Previous research, involving purely analytical techniques to simulations capturing behavior, has investigated questions and scenarios regarding the relationships among energy, emissions, air quality, and transportation. Primary limitations of past attempts have been availability of input data, useful "energy and behavior focused" models, validation data, and adequate computational capability that allows adequate understanding of the interdependencies of our transportation system. With increasing availability and quality of traditional and crowdsourced data, we have utilized the OpenStreetMap roads network, and has integrated high resolution population data with traffic simulation to create a Toolbox for Urban Mobility Simulations (TUMS) at global scale. TUMS consists of three major components: data processing, traffic simulation models, and Internet-based visualizations. It integrates OpenStreetMap, LandScanTM population, and other open data (Census Transportation Planning Products, National household Travel Survey, etc.) to generate both normal traffic operation and emergency evacuation scenarios. TUMS integrates TRANSIMS and MITSIM as traffic simulation engines, which are open-source and widely-accepted for scalable traffic simulations. Consistent data and simulation platform allows quick adaption to various geographic areas that has been demonstrated for multiple cities across the world. We are combining the strengths of geospatial data sciences, high performance simulations, transportation planning, and emissions, vehicle and energy technology development to design and develop a simulation

  17. A guide to calculating habitat-quality metrics to inform conservation of highly mobile species

    Bieri, Joanna A.; Sample, Christine; Thogmartin, Wayne E.; Diffendorfer, James E.; Earl, Julia E.; Erickson, Richard A.; Federico, Paula; Flockhart, D. T. Tyler; Nicol, Sam; Semmens, Darius J.; Skraber, T.; Wiederholt, Ruscena; Mattsson, Brady J.

    2018-01-01

    Many metrics exist for quantifying the relative value of habitats and pathways used by highly mobile species. Properly selecting and applying such metrics requires substantial background in mathematics and understanding the relevant management arena. To address this multidimensional challenge, we demonstrate and compare three measurements of habitat quality: graph-, occupancy-, and demographic-based metrics. Each metric provides insights into system dynamics, at the expense of increasing amounts and complexity of data and models. Our descriptions and comparisons of diverse habitat-quality metrics provide means for practitioners to overcome the modeling challenges associated with management or conservation of such highly mobile species. Whereas previous guidance for applying habitat-quality metrics has been scattered in diversified tracks of literature, we have brought this information together into an approachable format including accessible descriptions and a modeling case study for a typical example that conservation professionals can adapt for their own decision contexts and focal populations.Considerations for Resource ManagersManagement objectives, proposed actions, data availability and quality, and model assumptions are all relevant considerations when applying and interpreting habitat-quality metrics.Graph-based metrics answer questions related to habitat centrality and connectivity, are suitable for populations with any movement pattern, quantify basic spatial and temporal patterns of occupancy and movement, and require the least data.Occupancy-based metrics answer questions about likelihood of persistence or colonization, are suitable for populations that undergo localized extinctions, quantify spatial and temporal patterns of occupancy and movement, and require a moderate amount of data.Demographic-based metrics answer questions about relative or absolute population size, are suitable for populations with any movement pattern, quantify demographic

  18. Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

    Fujii, M.; Ishikawa, Y.; Ishihara, R.; Van der Cingel, J.; Mofrad, M.R.T.; Horita, M.; Uraoka, Y.

    2013-01-01

    In this study, we successfully achieved a relatively high field-effect mobility of 37.7?cm2/Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50?°C

  19. Water mobility in the endosperm of high beta-glucan barley mutants as studied by nuclear magnetic resonance imaging

    Seefeldt, Helene Fast; van den Berg, Frans W.J.; Köckenberger, Walter

    2007-01-01

    1H NMR imaging (MRI) was used as a noninvasive technique to study water distribution and mobility in hydrated barley (Hordeum vulgare L.) seeds of accessions with varying content of beta glucan (BG), a highly hygroscopic cell wall component. High contents of BG in barley are unfavorable in malting...... where it leads to clotting of filters and hazing of beer as well as in animal feed where it hinders the rapid uptake of energy. However, a high content of BG has a positive nutritional effect, as it lowers the cholesterol and the glycaemic index. It was studied whether water distribution and mobility...... were related to content and location of BG. Water mobility was investigated by following the rate and mode of desiccation in hydrated single seeds. In order to determine the different water components, a multispin echo experiment was set up to reveal the T2 transverse relaxation rates of water within...

  20. Barriers to fusion

    Berriman, A.C.; Butt, R.D.; Dasgupta, M.; Hinde, D.J.; Morton, C.R.; Newton, J.O.

    1999-01-01

    The fusion barrier is formed by the combination of the repulsive Coulomb and attractive nuclear forces. Recent research at the Australian National University has shown that when heavy nuclei collide, instead of a single fusion barrier, there is a set of fusion barriers. These arise due to intrinsic properties of the interacting nuclei such deformation, rotations and vibrations. Thus the range of barrier energies depends on the properties of both nuclei. The transfer of matter between nuclei, forming a neck, can also affect the fusion process. High precision data have been used to determine fusion barrier distributions for many nuclear reactions, leading to new insights into the fusion process

  1. High electron mobility recovery in AlGaN/GaN 2DEG channels regrown on etched surfaces

    Chan, Silvia H; DenBaars, Steven P; Keller, Stacia; Tahhan, Maher; Li, Haoran; Romanczyk, Brian; Mishra, Umesh K

    2016-01-01

    This paper reports high two-dimensional electron gas mobility attained from the regrowth of the AlGaN gating layer on ex situ GaN surfaces. To repair etch-damaged GaN surfaces, various pretreatments were conducted via metalorganic chemical vapor deposition, followed by a regrown AlGaN/GaN mobility test structure to evaluate the extent of recovery. The developed treatment process that was shown to significantly improve the electron mobility consisted of a N 2  + NH 3 pre-anneal plus an insertion of a 4 nm or thicker GaN interlayer prior to deposition of the AlGaN gating layer. Using the optimized process, a high electron mobility transistor (HEMT) device was fabricated which exhibited a high mobility of 1450 cm 2 V −1 s −1 (R sh  = 574 ohm/sq) and low dispersion characteristics. The additional inclusion of an in situ Al 2 O 3 dielectric into the regrowth process for MOS-HEMTs still preserved the transport properties near etch-impacted areas. (paper)

  2. Highly anisotropic mobility in solution processed TIPS-pentacene film studied by independently driven four GaIn probes

    Yoshimoto, Shinya; Takahashi, Kohtaro; Suzuki, Mitsuharu; Yamada, Hiroko; Miyahara, Ryosuke; Mukai, Kozo; Yoshinobu, Jun

    2017-08-01

    We have studied in-plane anisotropy in the field-effect mobility of solution-processed organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene by using independently driven four gallium indium (Ga-In) probes. Liquid-metal Ga-In probes are highly effective for reproducible conductivity measurements of organic thin films. We demonstrated that a high mobility anisotropy of 44 was obtained by using a square four-probe method and a feedback circuit to keep the channel potential constant. The present method minimized the influences of the contact resistance and the insensitivity of anisotropy in a linear arrangement in two-dimensional field-effect transistors.

  3. Two high-mobility group box domains act together to underwind and kink DNA

    Sánchez-Giraldo, R.; Acosta-Reyes, F. J. [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Malarkey, C. S. [University of Colorado School of Medicine, Aurora, CO 80045 (United States); Saperas, N. [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain); Churchill, M. E. A., E-mail: mair.churchill@ucdenver.edu [University of Colorado School of Medicine, Aurora, CO 80045 (United States); Campos, J. L., E-mail: mair.churchill@ucdenver.edu [Universitat Politecnica de Catalunya, 08028 Barcelona (Spain)

    2015-06-30

    The crystal structure of HMGB1 box A bound to an unmodified AT-rich DNA fragment is reported at a resolution of 2 Å. A new mode of DNA recognition for HMG box proteins is found in which two box A domains bind in an unusual configuration generating a highly kinked DNA structure. High-mobility group protein 1 (HMGB1) is an essential and ubiquitous DNA architectural factor that influences a myriad of cellular processes. HMGB1 contains two DNA-binding domains, box A and box B, which have little sequence specificity but have remarkable abilities to underwind and bend DNA. Although HMGB1 box A is thought to be responsible for the majority of HMGB1–DNA interactions with pre-bent or kinked DNA, little is known about how it recognizes unmodified DNA. Here, the crystal structure of HMGB1 box A bound to an AT-rich DNA fragment is reported at a resolution of 2 Å. Two box A domains of HMGB1 collaborate in an unusual configuration in which the Phe37 residues of both domains stack together and intercalate the same CG base pair, generating highly kinked DNA. This represents a novel mode of DNA recognition for HMGB proteins and reveals a mechanism by which structure-specific HMG boxes kink linear DNA.

  4. Isolated photosystem I reaction centers on a functionalized gated high electron mobility transistor.

    Eliza, Sazia A; Lee, Ida; Tulip, Fahmida S; Mostafa, Salwa; Greenbaum, Elias; Ericson, M Nance; Islam, Syed K

    2011-09-01

    In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale (~6 nm) reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs. © 2011 IEEE

  5. Two high-mobility group box domains act together to underwind and kink DNA

    Sánchez-Giraldo, R.; Acosta-Reyes, F. J.; Malarkey, C. S.; Saperas, N.; Churchill, M. E. A.; Campos, J. L.

    2015-01-01

    The crystal structure of HMGB1 box A bound to an unmodified AT-rich DNA fragment is reported at a resolution of 2 Å. A new mode of DNA recognition for HMG box proteins is found in which two box A domains bind in an unusual configuration generating a highly kinked DNA structure. High-mobility group protein 1 (HMGB1) is an essential and ubiquitous DNA architectural factor that influences a myriad of cellular processes. HMGB1 contains two DNA-binding domains, box A and box B, which have little sequence specificity but have remarkable abilities to underwind and bend DNA. Although HMGB1 box A is thought to be responsible for the majority of HMGB1–DNA interactions with pre-bent or kinked DNA, little is known about how it recognizes unmodified DNA. Here, the crystal structure of HMGB1 box A bound to an AT-rich DNA fragment is reported at a resolution of 2 Å. Two box A domains of HMGB1 collaborate in an unusual configuration in which the Phe37 residues of both domains stack together and intercalate the same CG base pair, generating highly kinked DNA. This represents a novel mode of DNA recognition for HMGB proteins and reveals a mechanism by which structure-specific HMG boxes kink linear DNA

  6. Isolated Photosystem I Reaction Centers on a Functionalized Gated High Electron Mobility Transistor

    Eliza, Sazia A. [University of Tennessee, Knoxville (UTK); Lee, Ida [ORNL; Tulip, Fahmida S [ORNL; Islam, Syed K [University of Tennessee, Knoxville (UTK); Mostafa, Salwa [University of Tennessee, Knoxville (UTK); Greenbaum, Elias [ORNL; Ericson, Milton Nance [ORNL

    2011-01-01

    In oxygenic plants, photons are captured with high quantum efficiency by two specialized reaction centers (RC) called Photosystem I (PS I) and Photosystem II (PS II). The captured photon triggers rapid charge separation and the photon energy is converted into an electrostatic potential across the nanometer-scale nm reaction centers. The exogenous photovoltages from a single PS I RC have been previously measured using the technique of Kelvin force probe microscopy (KFM). However, biomolecular photovoltaic applications require two-terminal devices. This paper presents for the first time, a micro-device for detection and characterization of isolated PS I RCs. The device is based on an AlGaN/GaN high electron mobility transistor (HEMT) structure. AlGaN/GaN HEMTs show high current throughputs and greater sensitivity to surface charges compared to other field-effect devices. PS I complexes immobilized on the floating gate of AlGaN/GaN HEMTs resulted in significant changes in the device characteristics under illumination. An analytical model has been developed to estimate the RCs of a major orientation on the functionalized gate surface of the HEMTs.

  7. Information barriers

    Fuller, J.L.; Wolford, J.

    2001-01-01

    measurement equipment, that the system is functioning properly and does not incorporate any hidden features (or 'switches') that allows the host to pass out-of-spec items. Authentication of information barrier systems is an extremely important concept to consider in designing and assembling these types of inspection systems. There are a limited set of straightforward approaches to authenticate such systems, when applied in conjunction with open and cooperative system design and fabrication, that will provide a high degree of confidence to both host and inspector that the system will prevent the release of classified information and yet still inspect items in a manner consistent with the objectives of an inspection agreement. These principles have been outlined in this paper, along with areas where additional studies would be helpful. (author)

  8. RNA Virus Evolution via a Quasispecies-Based Model Reveals a Drug Target with a High Barrier to Resistance

    Richard J. Bingham

    2017-11-01

    Full Text Available The rapid occurrence of therapy-resistant mutant strains provides a challenge for anti-viral therapy. An ideal drug target would be a highly conserved molecular feature in the viral life cycle, such as the packaging signals in the genomes of RNA viruses that encode an instruction manual for their efficient assembly. The ubiquity of this assembly code in RNA viruses, including major human pathogens, suggests that it confers selective advantages. However, their impact on viral evolution cannot be assessed in current models of viral infection that lack molecular details of virus assembly. We introduce here a quasispecies-based model of a viral infection that incorporates structural and mechanistic knowledge of packaging signal function in assembly to construct a phenotype-fitness map, capturing the impact of this RNA code on assembly yield and efficiency. Details of viral replication and assembly inside an infected host cell are coupled with a population model of a viral infection, allowing the occurrence of therapy resistance to be assessed in response to drugs inhibiting packaging signal recognition. Stochastic simulations of viral quasispecies evolution in chronic HCV infection under drug action and/or immune clearance reveal that drugs targeting all RNA signals in the assembly code collectively have a high barrier to drug resistance, even though each packaging signal in isolation has a lower barrier than conventional drugs. This suggests that drugs targeting the RNA signals in the assembly code could be promising routes for exploitation in anti-viral drug design.

  9. RNA Virus Evolution via a Quasispecies-Based Model Reveals a Drug Target with a High Barrier to Resistance.

    Bingham, Richard J; Dykeman, Eric C; Twarock, Reidun

    2017-11-17

    The rapid occurrence of therapy-resistant mutant strains provides a challenge for anti-viral therapy. An ideal drug target would be a highly conserved molecular feature in the viral life cycle, such as the packaging signals in the genomes of RNA viruses that encode an instruction manual for their efficient assembly. The ubiquity of this assembly code in RNA viruses, including major human pathogens, suggests that it confers selective advantages. However, their impact on viral evolution cannot be assessed in current models of viral infection that lack molecular details of virus assembly. We introduce here a quasispecies-based model of a viral infection that incorporates structural and mechanistic knowledge of packaging signal function in assembly to construct a phenotype-fitness map, capturing the impact of this RNA code on assembly yield and efficiency. Details of viral replication and assembly inside an infected host cell are coupled with a population model of a viral infection, allowing the occurrence of therapy resistance to be assessed in response to drugs inhibiting packaging signal recognition. Stochastic simulations of viral quasispecies evolution in chronic HCV infection under drug action and/or immune clearance reveal that drugs targeting all RNA signals in the assembly code collectively have a high barrier to drug resistance, even though each packaging signal in isolation has a lower barrier than conventional drugs. This suggests that drugs targeting the RNA signals in the assembly code could be promising routes for exploitation in anti-viral drug design.

  10. High-performance 4H-SiC junction barrier Schottky diodes with double resistive termination extensions

    Zheng Liu; Zhang Feng; Liu Sheng-Bei; Dong Lin; Liu Xing-Fang; Liu Bin; Yan Guo-Guo; Wang Lei; Zhao Wan-Shun; Sun Guo-Sheng; He Zhi; Fan Zhong-Chao; Yang Fu-Hua

    2013-01-01

    4H-SiC junction barrier Schottky (JBS) diodes with a high-temperature annealed resistive termination extension (HARTE) are designed, fabricated and characterized in this work. The differential specific on-state resistance of the device is as low as 3.64 mΩ·cm 2 with a total active area of 2.46 × 10 −3 cm 2 . Ti is the Schottky contact metal with a Schottky barrier height of 1.08 V and a low onset voltage of 0.7 V. The ideality factor is calculated to be 1.06. Al implantation annealing is performed at 1250°C in Ar, while good reverse characteristics are achieved. The maximum breakdown voltage is 1000 V with a leakage current of 9 × 10 −5 A on chip level. These experimental results show good consistence with the simulation results and demonstrate that high-performance 4H-SiC JBS diodes can be obtained based on the double HARTE structure. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  11. A low-frequency high-voltage rf-barrier-bunching system for high-intensity neutron source compressor rings

    Hardek, T.W.; Ziomek, C.; Rees, D.

    1995-01-01

    A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an rf-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in this case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured retrode amplifiers incorporating local rf feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with rf feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated

  12. The Effects of Intradistrict School Mobility and High Student Turnover Rates on Early Reading Achievement

    LeBoeuf, Whitney A.

    2013-01-01

    A number of studies have identified school mobility as one form of school disengagement that is disproportionately harmful for young children enrolled in large urban districts. However, there is substantial variation in these findings, with some studies actually evidencing positive associations between school mobility and academic outcomes (Mehana…

  13. Testing and analyses of a high temperature thermal barrier for gas-cooled reactors

    Black, W.E.; Betts, W.S.; Felten, P.

    1979-01-01

    A full size, multi-panel section of a thermal barrier system was fabricated from a nickel-base superalloy and a combination of fibrous blanket insulation materials for specific application in a steam cycle gas-cooled nuclear reactor. The 2.4 m square array was representative of the sidewall of the lower core outlet plenum and included coverplates, attachments, seals, and a simulated water-cooled liner. Testing was conducted in a reactor grade, helium-filled chamber at 816 0 C for 100 hours, which established a normal (baseline) condition; 982 0 C for 10 hours, which satisfied an emergency condition; 1093 0 C for 1 hour, which simulated a faulted condition; and 1260 0 C, which was a non-design condition test to demonstrate the temperature overshoot capability of the system. Post-test examination indicated: (1) an acceptable performance by the anti-friction chromium carbide (Cr 3 C 2 ) coating; (2) no significant galling between non-coated surfaces; (3) no distortion of attachment fixtures; (4) predictable coverplate deflection during the design conditions testing (normal, emergency, and faulted); and (5) considerable plastic deformation resulting from the near-incipient melting temperature. (orig.)

  14. Behaviour of tetraalkylammonium ions in high-field asymmetric waveform ion mobility spectrometry.

    Aksenov, Alexander A; Kapron, James T

    2010-05-30

    High-field asymmetric waveform ion mobility spectrometry (FAIMS) is an ion-filtering technique recently adapted for use with liquid chromatography/mass spectrometry (LC/MS) to remove interferences during analysis of complex matrices. This is the first systematic study of a series of singly charged tetraalkylammonium ions by FAIMS-MS. The compensation voltage (CV) is the DC offset of the waveform which permits the ion to emerge from FAIMS and it was determined for each member of the series under various conditions. The electrospray ionization conditions explored included spray voltage, vaporizer temperature, and sheath and auxiliary gas pressure. The FAIMS conditions explored included carrier gas flow rate, electrode temperature and composition of the carrier gas. Optimum desolvation was achieved using sufficient carrier gas (flow rate > or = 2 L/min) to ensure stable response. Low-mass ions (m/z 100-200) are more susceptible to changes in electrode temperature and gas composition than high mass ions (m/z 200-700). As a result of this study, ions are reliably analyzed using standard FAIMS conditions (dispersion voltage -5000 V, carrier gas flow rate 3 L/min, 50% helium/50%nitrogen, inner electrode temperature 70 degrees C and outer electrode temperature 90 degrees C). Variation of FAIMS conditions may be of great use for the separation of very low mass tetraalkylammonium (TAA) ions from other TAA ions. The FAIMS conditions do not appear to have a major effect on higher mass ions. Copyright 2010 John Wiley & Sons, Ltd.

  15. Angle-dependent magnetoresistance and quantum oscillations in high-mobility semimetal LuPtBi

    Xu, Guizhou; Hou, Zhipeng; Wang, Yue; Zhang, Xiaoming; Zhang, Hongwei; Liu, Enke; Xi, X; Xu, Feng; Wu, Guangheng; Zhang, Xixiang; Wang, Wenhong

    2017-01-01

    The recent discovery of ultrahigh mobility and large positive magnetoresistance in topologically non-trivial Half-Heusler semimetal LuPtBi provides a unique playground for studying exotic physics and significant perspective for device applications. As an fcc-structured electron-hole-compensated semimetal, LuPtBi theoretically exhibits six symmetrically arranged anisotropic electron Fermi pockets and two nearly-spherical hole pockets, offering the opportunity to explore the physics of Fermi surface with a simple angle-related magnetotransport properties. In this work, through the angle-dependent transverse magnetoresistance measurements, in combination with high-field SdH quantum oscillations, we achieved to map out a Fermi surface with six anisotropic pockets in the high-temperature and low-field regime, and furthermore, identify a possible magnetic field driven Fermi surface change at lower temperatures. Reasons account for the Fermi surface change in LuPtBi are discussed in terms of the field-induced electron evacuation due to Landau quantization.

  16. Resonant tunneling assisted propagation and amplification of plasmons in high electron mobility transistors

    Bhardwaj, Shubhendu; Sensale-Rodriguez, Berardi; Xing, Huili Grace; Rajan, Siddharth; Volakis, John L.

    2016-01-01

    A rigorous theoretical and computational model is developed for the plasma-wave propagation in high electron mobility transistor structures with electron injection from a resonant tunneling diode at the gate. We discuss the conditions in which low-loss and sustainable plasmon modes can be supported in such structures. The developed analytical model is used to derive the dispersion relation for these plasmon-modes. A non-linear full-wave-hydrodynamic numerical solver is also developed using a finite difference time domain algorithm. The developed analytical solutions are validated via the numerical solution. We also verify previous observations that were based on a simplified transmission line model. It is shown that at high levels of negative differential conductance, plasmon amplification is indeed possible. The proposed rigorous models can enable accurate design and optimization of practical resonant tunnel diode-based plasma-wave devices for terahertz sources, mixers, and detectors, by allowing a precise representation of their coupling when integrated with other electromagnetic structures

  17. Increased serum levels of high mobility group box 1 protein in patients with autistic disorder.

    Emanuele, Enzo; Boso, Marianna; Brondino, Natascia; Pietra, Stefania; Barale, Francesco; Ucelli di Nemi, Stefania; Politi, Pierluigi

    2010-05-30

    High mobility group box 1 (HMGB1) is a highly conserved, ubiquitous protein that functions as an activator for inducing the immune response and can be released from neurons after glutamate excitotoxicity. The objective of the present study was to measure serum levels of HMGB1 in patients with autistic disorder and to study their relationship with clinical characteristics. We enrolled 22 adult patients with autistic disorder (mean age: 28.1+/-7.7 years) and 28 age- and gender-matched healthy controls (mean age: 28.7+/-8.1 years). Serum levels of HMGB1 were measured by enzyme-linked immunosorbent assay (ELISA). Compared with healthy subjects, serum levels of HMGB1 were significantly higher in patients with autistic disorder (10.8+/-2.6 ng/mL versus 5.6+/-2.5 ng/mL, respectively, Pautistic disorder. Increased HMGB1 may be a biological correlate of the impaired reciprocal social interactions in this neurodevelopmental disorder. Copyright 2010 Elsevier Inc. All rights reserved.

  18. Expression and Effects of High-Mobility Group Box 1 in Cervical Cancer

    Xiaoao Pang

    2014-05-01

    Full Text Available We investigated the significance of high- mobility group box1 (HMGB1 and T-cell-mediated immunity and prognostic value in cervical cancer. HMGB1, forkhead/winged helix transcription factor p3 (Foxp3, IL-2, and IL-10 protein expression was analyzed in 100 cervical tissue samples including cervical cancer, cervical intraepithelial neoplasia (CIN, and healthy control samples using immunohistochemistry. Serum squamous cell carcinoma antigen (SCC-Ag was immunoradiometrically measured in 32 serum samples from 37 cases of squamous cervical cancer. HMGB1 and SCC-Ag were then correlated to clinicopathological characteristics. HMGB1 expression tends to increase as cervical cancer progresses and it was found to be significantly correlated to FIGO stage and lymph node metastasis. These findings suggest that HMGB1 may be a useful prognostic indicator of cervical carcinoma. In addition, there were significant positive relationships between HMGB1 and FOXP3 or IL-10 expression (both p < 0.05. In contrast, HMGB1 and IL-2 expression was negatively correlated (p < 0.05. HMGB1 expression may activate Tregs or facilitate Th2 polarization to promote immune evasion of cervical cancer. Elevated HMGB1 protein in cervical carcinoma samples was associated with a high recurrence of HPV infection in univariate analysis (p < 0.05. HMGB1 expression and levels of SCC-Ag were directly correlated in SCC (p < 0.05. Thus, HMGB1 may be a useful biomarker for patient prognosis and cervical cancer prediction and treatment.

  19. High strength-of-ties and low mobility enable the evolution of third-party punishment

    Roos, Patrick; Gelfand, Michele; Nau, Dana; Carr, Ryan

    2014-01-01

    As punishment can be essential to cooperation and norm maintenance but costly to the punisher, many evolutionary game-theoretic studies have explored how direct punishment can evolve in populations. Compared to direct punishment, in which an agent acts to punish another for an interaction in which both parties were involved, the evolution of third-party punishment (3PP) is even more puzzling, because the punishing agent itself was not involved in the original interaction. Despite significant empirical studies of 3PP, little is known about the conditions under which it can evolve. We find that punishment reputation is not, by itself, sufficient for the evolution of 3PP. Drawing on research streams in sociology and psychology, we implement a structured population model and show that high strength-of-ties and low mobility are critical for the evolution of responsible 3PP. Only in such settings of high social-structural constraint are punishers able to induce self-interested agents toward cooperation, making responsible 3PP ultimately beneficial to individuals as well as the collective. Our results illuminate the conditions under which 3PP is evolutionarily adaptive in populations. Responsible 3PP can evolve and induce cooperation in cases where other mechanisms alone fail to do so. PMID:24335985

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

    Freeman, Jon C.

    2003-01-01

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

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

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

    2017-11-01

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

  2. Monte Carlo simulation of ballistic transport in high-mobility channels

    Sabatini, G; Marinchio, H; Palermo, C; Varani, L; Daoud, T; Teissier, R [Institut d' Electronique du Sud (CNRS UMR 5214) - Universite Montpellier II (France); Rodilla, H; Gonzalez, T; Mateos, J, E-mail: sabatini@ies.univ-montp2.f [Departamento de Fisica Aplicada - Universidad de Salamanca (Spain)

    2009-11-15

    By means of Monte Carlo simulations coupled with a two-dimensional Poisson solver, we evaluate directly the possibility to use high mobility materials in ultra fast devices exploiting ballistic transport. To this purpose, we have calculated specific physical quantities such as the transit time, the transit velocity, the free flight time and the mean free path as functions of applied voltage in InAs channels with different lengths, from 2000 nm down to 50 nm. In this way the transition from diffusive to ballistic transport is carefully described. We remark a high value of the mean transit velocity with a maximum of 14x10{sup 5} m/s for a 50 nm-long channel and a transit time shorter than 0.1 ps, corresponding to a cutoff frequency in the terahertz domain. The percentage of ballistic electrons and the number of scatterings as functions of distance are also reported, showing the strong influence of quasi-ballistic transport in the shorter channels.

  3. Monte Carlo simulation of ballistic transport in high-mobility channels

    Sabatini, G; Marinchio, H; Palermo, C; Varani, L; Daoud, T; Teissier, R; Rodilla, H; Gonzalez, T; Mateos, J

    2009-01-01

    By means of Monte Carlo simulations coupled with a two-dimensional Poisson solver, we evaluate directly the possibility to use high mobility materials in ultra fast devices exploiting ballistic transport. To this purpose, we have calculated specific physical quantities such as the transit time, the transit velocity, the free flight time and the mean free path as functions of applied voltage in InAs channels with different lengths, from 2000 nm down to 50 nm. In this way the transition from diffusive to ballistic transport is carefully described. We remark a high value of the mean transit velocity with a maximum of 14x10 5 m/s for a 50 nm-long channel and a transit time shorter than 0.1 ps, corresponding to a cutoff frequency in the terahertz domain. The percentage of ballistic electrons and the number of scatterings as functions of distance are also reported, showing the strong influence of quasi-ballistic transport in the shorter channels.

  4. Angle-dependent magnetoresistance and quantum oscillations in high-mobility semimetal LuPtBi

    Xu, Guizhou

    2017-03-14

    The recent discovery of ultrahigh mobility and large positive magnetoresistance in topologically non-trivial Half-Heusler semimetal LuPtBi provides a unique playground for studying exotic physics and significant perspective for device applications. As an fcc-structured electron-hole-compensated semimetal, LuPtBi theoretically exhibits six symmetrically arranged anisotropic electron Fermi pockets and two nearly-spherical hole pockets, offering the opportunity to explore the physics of Fermi surface with a simple angle-related magnetotransport properties. In this work, through the angle-dependent transverse magnetoresistance measurements, in combination with high-field SdH quantum oscillations, we achieved to map out a Fermi surface with six anisotropic pockets in the high-temperature and low-field regime, and furthermore, identify a possible magnetic field driven Fermi surface change at lower temperatures. Reasons account for the Fermi surface change in LuPtBi are discussed in terms of the field-induced electron evacuation due to Landau quantization.

  5. The Impact of Low, Moderate, and High Military Family Mobility School District Transfer Rates on Graduating Senior High School Dependents' Achievement and School Engagement

    Rippe, Jeffrey K.

    2012-01-01

    The results of this study suggest that there were no significant differences in the academic performance of military dependents' with low (n = 20), moderate (n = 20), and high (n = 20) mobility school district transfer rates compared to non-military control students (n = 20) before completing high school. The findings were not consistent with…

  6. Application of a Barrier Filter at a High Purity Synthetic Graphite Plant, CRADA 99-F035, Final Report

    National Energy Technology Laboratory

    2000-08-31

    Superior Graphite Company and the US Department of Energy have entered into a Cooperative Research and Development Agreement (CRADA) to study the application of ceramic barrier filters at its Hopkinsville, Kentucky graphite plant. Superior Graphite Company is a worldwide leader in the application of advanced thermal processing technology to produce high purity graphite and carbons. The objective of the CRADA is to determine the technical and economic feasibility of incorporating the use of high-temperature filters to improve the performance of the offgas treatment system. A conceptual design was developed incorporating the ceramic filters into the offgas treatment system to be used for the development of a capital cost estimate and economic feasibility assessment of this technology for improving particulate removal. This CRADA is a joint effort of Superior Graphite Company, Parsons Infrastructure and Technology Group, and the National Energy Technology Laboratory (NETL) of the US Department of Energy (DOE).

  7. Highly organic natural media as permeable reactive barriers: TCE partitioning and anaerobic degradation profile in eucalyptus mulch and compost.

    Öztürk, Zuhal; Tansel, Berrin; Katsenovich, Yelena; Sukop, Michael; Laha, Shonali

    2012-10-01

    Batch and column experiments were conducted with eucalyptus mulch and commercial compost to evaluate suitability of highly organic natural media to support anaerobic decomposition of trichloroethylene (TCE) in groundwater. Experimental data for TCE and its dechlorination byproducts were analyzed with Hydrus-1D model to estimate the partitioning and kinetic parameters for the sequential dechlorination reactions during TCE decomposition. The highly organic natural media allowed development of a bioactive zone capable of decomposing TCE under anaerobic conditions. The first order TCE biodecomposition reaction rates were 0.23 and 1.2d(-1) in eucalyptus mulch and compost media, respectively. The retardation factors in the eucalyptus mulch and compost columns for TCE were 35 and 301, respectively. The results showed that natural organic soil amendments can effectively support the anaerobic bioactive zone for remediation of TCE contaminated groundwater. The natural organic media are effective environmentally sustainable materials for use in permeable reactive barriers. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Highly efficient fully flexible indium tin oxide free organic light emitting diodes fabricated directly on barrier-foil

    Bocksrocker, Tobias; Hülsmann, Neele; Eschenbaum, Carsten; Pargner, Andreas; Höfle, Stefan; Maier-Flaig, Florian; Lemmer, Uli

    2013-01-01

    We present a simple method for the fabrication of highly conductive and fully flexible metal/polymer hybrid anodes for efficient organic light emitting diodes (OLEDs). By incorporating ultra-thin metal grids into a conductive polymer, we fabricated anodes with very low sheet resistances and high transparency. After optimizing the metallic grid, OLEDs with these hybrid anodes are superior to OLEDs with standard indium tin oxide (ITO) anodes in luminous efficacy by a factor of ∼ 2. Furthermore, the sheet resistance can be reduced by up to an order of magnitude compared to ITO on polyethylene terephthalate (PET). The devices show a very low turn-on voltage and the hybrid anodes do not change the emissive spectra of the OLEDs. In addition, we fabricated the anodes directly on a barrier foil, making the double sided encapsulation of a typically used PET-substrate unnecessary

  9. Application of a Barrier Filter at a High Purity Synthetic Graphite Plant, CRADA 99-F035, Final Report; FINAL

    National Energy Technology Laboratory

    2000-01-01

    Superior Graphite Company and the US Department of Energy have entered into a Cooperative Research and Development Agreement (CRADA) to study the application of ceramic barrier filters at its Hopkinsville, Kentucky graphite plant. Superior Graphite Company is a worldwide leader in the application of advanced thermal processing technology to produce high purity graphite and carbons. The objective of the CRADA is to determine the technical and economic feasibility of incorporating the use of high-temperature filters to improve the performance of the offgas treatment system. A conceptual design was developed incorporating the ceramic filters into the offgas treatment system to be used for the development of a capital cost estimate and economic feasibility assessment of this technology for improving particulate removal. This CRADA is a joint effort of Superior Graphite Company, Parsons Infrastructure and Technology Group, and the National Energy Technology Laboratory (NETL) of the US Department of Energy (DOE)

  10. From mobile ADCP to high-resolution SSC: a cross-section calibration tool

    Boldt, Justin A.

    2015-01-01

    Sediment is a major cause of stream impairment, and improved sediment monitoring is a crucial need. Point samples of suspended-sediment concentration (SSC) are often not enough to provide an understanding to answer critical questions in a changing environment. As technology has improved, there now exists the opportunity to obtain discrete measurements of SSC and flux while providing a spatial scale unmatched by any other device. Acoustic instruments are ubiquitous in the U.S. Geological Survey (USGS) for making streamflow measurements but when calibrated with physical sediment samples, they may be used for sediment measurements as well. The acoustic backscatter measured by an acoustic Doppler current profiler (ADCP) has long been known to correlate well with suspended sediment, but until recently, it has mainly been qualitative in nature. This new method using acoustic surrogates has great potential to leverage the routine data collection to provide calibrated, quantitative measures of SSC which hold promise to be more accurate, complete, and cost efficient than other methods. This extended abstract presents a method for the measurement of high spatial and temporal resolution SSC using a down-looking, mobile ADCP from discrete cross-sections. The high-resolution scales of sediment data are a primary advantage and a vast improvement over other discrete methods for measuring SSC. Although acoustic surrogate technology using continuous, fixed-deployment ADCPs (side-looking) is proven, the same methods cannot be used with down-looking ADCPs due to the fact that the SSC and particle-size distribution variation in the vertical profile violates theory and complicates assumptions. A software tool was developed to assist in using acoustic backscatter from a down-looking, mobile ADCP as a surrogate for SSC. This tool has a simple graphical user interface that loads the data, assists in the calibration procedure, and provides data visualization and output options. This tool

  11. Mobile Learning Based Worked Example in Electric Circuit (WEIEC) Application to Improve the High School Students' Electric Circuits Interpretation Ability

    Yadiannur, Mitra; Supahar

    2017-01-01

    This research aims to determine the feasibility and effectivity of mobile learning based Worked Example in Electric Circuits (WEIEC) application in improving the high school students' electric circuits interpretation ability on Direct Current Circuits materials. The research method used was a combination of Four-D Models and ADDIE model. The…

  12. High mobility group box1 (HMGB1) in relation to cutaneous inflammation in systemic lupus erythematosus (SLE)

    Abdulahad, D.A.; Westra, J.; Reefman, E.; Zuidersma, E.; Bijzet, J.; Limburg, P.C.; Kallenberg, C.G.M.; Bijl, M.

    2013-01-01

    Photosensitivity is characteristic of systemic lupus erythematosus (SLE). Upon ultraviolet B (UVB) exposure, patients develop inflammatory skin lesions in the vicinity of sunburn cells (SBCs). High mobility group box 1 (HMGB1) is released from apoptotic and activated cells and exerts inflammatory

  13. Enhanced mobility of poly(3-hexylthiophene) transistors by spin-coating from high-boiling-point solvents

    Chang, J.F.; Sun, B.Q.; Breiby, Dag Werner

    2004-01-01

    chloroform are typically on the order of 0.01 cm(2)/(V s). Here we investigate a range of solvents with higher boiling points. We find that 1,2,4-trichlorobenzene with good solubility and a high boiling point significantly improves the field-effect mobilities up to 0.12 cm(2)/(V s) with on:off ratios of 10...

  14. Sequence-specific high mobility group box factors recognize 10-12-base pair minor groove motifs

    van Beest, M; Dooijes, D; van De Wetering, M

    2000-01-01

    Sequence-specific high mobility group (HMG) box factors bind and bend DNA via interactions in the minor groove. Three-dimensional NMR analyses have provided the structural basis for this interaction. The cognate HMG domain DNA motif is generally believed to span 6-8 bases. However, alignment...

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

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

    2014-01-01

    This study presents a method to characterise thermal resistances and capacitances of GaN high-electron-mobility transistors (HEMTs) through dynamic electrothermal measurements. A measured relation between RF gain and the channel temperature (Tc) is formed and used for indirect measurements...

  16. High electron mobility and quantum oscillations in non-encapsulated ultrathin semiconducting Bi2O2Se

    Wu, Jinxiong; Yuan, Hongtao; Meng, Mengmeng; Chen, Cheng; Sun, Yan; Chen, Zhuoyu; Dang, Wenhui; Tan, Congwei; Liu, Yujing; Yin, Jianbo; Zhou, Yubing; Huang, Shaoyun; Xu, H. Q.; Cui, Yi; Hwang, Harold Y.; Liu, Zhongfan; Chen, Yulin; Yan, Binghai; Peng, Hailin

    2017-07-01

    High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ˜0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm2 V-1 s-1 is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm2 V-1 s-1), large current on/off ratios (>106) and near-ideal subthreshold swing values (˜65 mV dec-1) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.

  17. Thermal instability and the growth of the InGaAs/AlGaAs pseudomorphic high electron mobility transistor system

    Pellegrino, Joseph G.; Qadri, Syed B.; Mahadik, Nadeemullah A.; Rao, Mulpuri V.; Tseng, Wen F.; Thurber, Robert; Gajewski, Donald; Guyer, Jonathan

    2007-01-01

    The effects of temperature overshoot during molecular beam epitaxy growth on the transport properties of conventionally and delta-doped pseudomorphic high electron mobility transistor (pHEMT) structures have been examined. A diffuse reflectance spectroscopy (DRS)-controlled versus a thermocouple (TC)-controlled, growth scheme is compared. Several advantages of the DRS-grown pHEMTs over the TC-controlled version were observed. Modest improvements in mobility, on the order of 2%-3%, were observed in addition to a 20% reduction in carrier freeze-out for the DRS-grown pHEMTs at 77 K

  18. Role of transport band edge variation on delocalized charge transport in high-mobility crystalline organic semiconductors

    Kadashchuk, Andrey; Tong, Fei; Janneck, Robby; Fishchuk, Ivan I.; Mityashin, Alexander; Pavlica, Egon; Köhler, Anna; Heremans, Paul; Rolin, Cedric; Bratina, Gvido; Genoe, Jan

    2017-09-01

    We demonstrate that the degree of charge delocalization has a strong impact on polarization energy and thereby on the position of the transport band edge in organic semiconductors. This gives rise to long-range potential fluctuations, which govern the electronic transport through delocalized states in organic crystalline layers. This concept is employed to formulate an analytic model that explains a negative field dependence coupled with a positive temperature dependence of the charge mobility observed by a lateral time-of-flight technique in a high-mobility crystalline organic layer. This has important implications for the further understanding of the charge transport via delocalized states in organic semiconductors.

  19. Two-frequency method for measuring Hall emf in high-resistive materials with charge-carrier low mobility

    Aleksandrov, A.L.; Vedeneev, A.S.; Gulyaev, I.B.; Zhdan, A.G.

    1982-01-01

    A facility for measuring Hall emf in high-resistive materials with low mobility of charge carriers by the two-frequency method using digital synchronous integration is described. The facility permits to detect the minimum Hall emf approxamatety equat to 5 μV at approximatety equal to 1 T Ohm of the investigated.sample resistance during the measuring time of approximately equal to 2000 s. Sensitivity by Hall mobility makes up >= 0.01 cm 2 /Vxs at the same measuring time. Measuring results of the Hall emf on GaAs monocrystals, CdSe films and island film of gold are presented

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

    Chang, P. C.; Lee, K. H.; Wang, Z. H.; Chang, S. J.

    2014-01-01

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

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

    P. C. Chang

    2014-01-01

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

  2. Electronic parameters of high barrier Au/Rhodamine-101/n-Inp Schottky diode with organic ınterlayer

    Güllü, Ö.; Aydoğan, S.; Türüt, A.

    2012-01-01

    In this work, we present that Rhodamine-101 (Rh-101) organic molecules can control the electrical characteristics of conventional Au/n-InP metal–semiconductor contacts. An Au/n-InP Schottky junction with Rh-101 interlayer has been formed by using a simple cast process. A potential barrier height as high as 0.88 eV has been achieved for Au/Rh-101/n-InP Schottky diodes, which have good current–voltage (I–V) characteristics. This good performance is attributed to the effect of formation of interfacial organic thin layer between Au and n-InP. By using capacitance-voltage measurement of the Au/Rh-101/n-InP Schottky diode the diffusion potential and the barrier height have been calculated as 0.78 V and 0.88 eV, respectively. From the I–V measurement of the diode under illumination, short circuit current and open circuit voltage have been extracted as 1.70 μA and 240 mV, respectively.

  3. Efficient sampling over rough energy landscapes with high barriers: A combination of metadynamics with integrated tempering sampling

    Yang, Y. Isaac [Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Zhang, Jun; Che, Xing; Yang, Lijiang; Gao, Yi Qin, E-mail: gaoyq@pku.edu.cn [Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China); Biodynamic Optical Imaging Center, Peking University, Beijing 100871 (China)

    2016-03-07

    In order to efficiently overcome high free energy barriers embedded in a complex energy landscape and calculate overall thermodynamics properties using molecular dynamics simulations, we developed and implemented a sampling strategy by combining the metadynamics with (selective) integrated tempering sampling (ITS/SITS) method. The dominant local minima on the potential energy surface (PES) are partially exalted by accumulating history-dependent potentials as in metadynamics, and the sampling over the entire PES is further enhanced by ITS/SITS. With this hybrid method, the simulated system can be rapidly driven across the dominant barrier along selected collective coordinates. Then, ITS/SITS ensures a fast convergence of the sampling over the entire PES and an efficient calculation of the overall thermodynamic properties of the simulation system. To test the accuracy and efficiency of this method, we first benchmarked this method in the calculation of ϕ − ψ distribution of alanine dipeptide in explicit solvent. We further applied it to examine the design of template molecules for aromatic meta-C—H activation in solutions and investigate solution conformations of the nonapeptide Bradykinin involving slow cis-trans isomerizations of three proline residues.

  4. Poly(butylene 2,5-thiophenedicarboxylate: An Added Value to the Class of High Gas Barrier Biopolyesters

    Giulia Guidotti

    2018-02-01

    Full Text Available Many efforts are currently devoted to the design and development of high performance bioplastics to replace traditional fossil-based polymers. In response, this contribution presents a new biobased aromatic polyester, i.e., poly(butylene 2,5-thiophenedicarboxylate (PBTF. Here, PBTF is characterized from the molecular, thermo-mechanical and structural point of view. Gas permeability is evaluated at different temperatures, in the range below and above glass transition, providing a full insight into the performances of this material under different operating conditions, and demonstrating the superior gas barrier behavior of PBTF with respect to other polyesters, such as PEF and PET. The combination of calorimetric and diffractometric studies allows for a deep understanding of the structure of PBTF, revealing the presence of a not-induced 2D-ordered phase (meso-phase, responsible for its outstanding gas permeability behavior. The simple synthetic strategy adopted, the exceptional barrier properties, combined with the interesting mechanical characteristics of PBTF open up new scenarios in the world of green and sustainable packaging materials.

  5. Development of practical field minimised personal hands free headset for mobile phones with high performance robustness

    Gosnell, M.E.; Huber, G.

    2001-01-01

    This paper presents the development of a practical means of minimising exposure of the user's head to radiated emissions from mobile phones. The invention allows the production of a commercially viable product similar to the existing and widely accepted hands free headsets. The description of the design evolution concentrates on various techniques for attenuating the power emissions at the earpiece and the corresponding results will be disclosed including measurements taken with the mobile held in several typical positions. The design focuses on maximising immunity to phone and wire position with maximum attenuation in the commercial mobile bands. Copyright (2001) Australasian Radiation Protection Society Inc

  6. Basic design and construction of a mobile hot cell for the conditioning of spent high activity radioactive sources

    An Hongxiang; Fan Zhiwen; Al-Mughrabi, M.

    2011-01-01

    The conditioning of spent high activity radioactive sources is one important step in sealed radioactive sources management strategies. Based on the practice on the designing of the immobilized hot cell, the handling of the sealed radioactive sources, and the reference of the mobile hot cell constructed in South Africa, SHARS conditioning process and the basic design of a mobile hot cell is developed. The mobile hot cell has been constructed and the tests including the cold test of the SRS conditioning, the hot cell assemble and disassemble and SRS recovery were done. The shielding capacity were tested by 3.8 x 10 13 Bq cobalt-60 sources and the dose rate of the equipment surface, below 2 m, is less than 0.016 mSv/h. It is proved that the designing requirement is meet and the function of the equipment is good. (authors)

  7. High mobility organic field-effect transistor based on water-soluble deoxyribonucleic acid via spray coating

    Shi, Wei; Han, Shijiao; Huang, Wei; Yu, Junsheng, E-mail: jsyu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Information, University of Electronic Science and Technology of China (UESTC), Chengdu 610054 (China)

    2015-01-26

    High mobility organic field-effect transistors (OFETs) by inserting water-soluble deoxyribonucleic acid (DNA) buffer layer between electrodes and pentacene film through spray coating process were fabricated. Compared with the OFETs incorporated with DNA in the conventional organic solvents of ethanol and methanol: water mixture, the water-soluble DNA based OFET exhibited an over four folds enhancement of field-effect mobility from 0.035 to 0.153 cm{sup 2}/Vs. By characterizing the surface morphology and the crystalline structure of pentacene active layer through atomic force microscope and X-ray diffraction, it was found that the adoption of water solvent in DNA solution, which played a key role in enhancing the field-effect mobility, was ascribed to both the elimination of the irreversible organic solvent-induced bulk-like phase transition of pentacene film and the diminution of a majority of charge trapping at interfaces in OFETs.

  8. Biology and ecology of the vulnerable holothuroid, Stichopus herrmanni, on a high-latitude coral reef on the Great Barrier Reef

    Wolfe, Kennedy; Byrne, Maria

    2017-12-01

    Tropical aspidochirotid holothuroids are among the largest coral reef invertebrates, but gaps remain in our understanding of their ecological roles in lagoon sediment habitats, a vast component of coral-reef ecosystems. Stichopus herrmanni, listed as vulnerable (IUCN), is currently a major fishery species on the Great Barrier Reef (GBR) and throughout the Indo-Pacific. It is critical to characterise how this species interacts with its environment to understand how its removal may impact ecosystem functionality. We investigated seasonal variation in movement, bioturbation, feeding and gonad development of S. herrmanni over 3 yr at One Tree Reef, which has been a no-take area for decades. We determined the direct influence of the deposit-feeding activity of S. herrmanni on sediment turnover and granulometry, and on the abundance of infauna and benthic productivity in a comprehensive in situ analysis of tropical holothuroid feeding ecology. This species is highly mobile with identifiable individuals exhibiting site fidelity over 3 yr. With the potential to turn over an estimated 64-250 kg individual-1 yr-1, S. herrmanni is a major bioturbator. Stichopus herrmanni is a generalist feeder and influences trophic interactions by altering the abundance of infauna and microalgae. Stichopus herrmanni exhibited decreased feeding activity and gonad development in winter, the first documentation of a seasonal disparity in the bioturbation activity of a tropical holothuroid. Sediment digestion and dissolution by S. herrmanni has the potential to influence seawater chemistry, a particularly important feature in a changing ocean. Our results provide essential baseline data on the functional roles of this ecologically important species to inform development of ecosystem-based bêche-de-mer fisheries management on the GBR.

  9. Fabrication of enhancement-mode AlGaN/GaN high electron mobility transistors using double plasma treatment

    Lim, Jong-Won, E-mail: jwlim@etri.re.kr [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Ahn, Ho-Kyun; Kim, Seong-il; Kang, Dong-Min; Lee, Jong-Min; Min, Byoung-Gue; Lee, Sang-Heung; Yoon, Hyung-Sup; Ju, Chull-Won; Kim, Haecheon; Mun, Jae-Kyoung; Nam, Eun-Soo [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Park, Hyung-Moo [Photonic/Wireless Convergence Components Dept., IT Materials and Components Lab., Electronics and Telecommunications Research Institute, Daejeon 305-700 (Korea, Republic of); Division of Electronics and Electrical Engineering, Dongguk University, Seoul (Korea, Republic of)

    2013-11-29

    We report the fabrication and DC and microwave characteristics of 0.5 μm AlGaN/GaN high electron mobility transistors using double plasma treatment process. Silicon nitride layers 700 and 150 Å thick were deposited by plasma-enhanced chemical vapor deposition at 260 °C to protect the device and to define the gate footprint. The double plasma process was carried out by two different etching techniques to obtain enhancement-mode AlGaN/GaN high electron mobility transistors with 0.5 μm gate lengths. The enhancement-mode AlGaN/GaN high electron mobility transistor was prepared in parallel to the depletion-mode AlGaN/GaN high electron mobility transistor device on one wafer. Completed double plasma treated 0.5 μm AlGaN/GaN high electron mobility transistor devices fabricated by dry etching exhibited a peak transconductance, gm, of 330 mS/mm, a breakdown voltage of 115 V, a current-gain cutoff frequency (f{sub T}) of 18 GHz, and a maximum oscillation frequency (f{sub max}) of 66 GHz. - Highlights: • The double plasma process was carried out by two different etching techniques. • Double plasma treated device exhibited a transconductance of 330 mS/mm. • Completed 0.5 μm gate device exhibited a current-gain cutoff frequency of 18 GHz. • The off-state breakdown voltage of 115 V for 0.5 μm gate device was obtained. • Continuous-wave output power density of 4.3 W/mm was obtained at 2.4 GHz.

  10. Fabrication of enhancement-mode AlGaN/GaN high electron mobility transistors using double plasma treatment

    Lim, Jong-Won; Ahn, Ho-Kyun; Kim, Seong-il; Kang, Dong-Min; Lee, Jong-Min; Min, Byoung-Gue; Lee, Sang-Heung; Yoon, Hyung-Sup; Ju, Chull-Won; Kim, Haecheon; Mun, Jae-Kyoung; Nam, Eun-Soo; Park, Hyung-Moo

    2013-01-01

    We report the fabrication and DC and microwave characteristics of 0.5 μm AlGaN/GaN high electron mobility transistors using double plasma treatment process. Silicon nitride layers 700 and 150 Å thick were deposited by plasma-enhanced chemical vapor deposition at 260 °C to protect the device and to define the gate footprint. The double plasma process was carried out by two different etching techniques to obtain enhancement-mode AlGaN/GaN high electron mobility transistors with 0.5 μm gate lengths. The enhancement-mode AlGaN/GaN high electron mobility transistor was prepared in parallel to the depletion-mode AlGaN/GaN high electron mobility transistor device on one wafer. Completed double plasma treated 0.5 μm AlGaN/GaN high electron mobility transistor devices fabricated by dry etching exhibited a peak transconductance, gm, of 330 mS/mm, a breakdown voltage of 115 V, a current-gain cutoff frequency (f T ) of 18 GHz, and a maximum oscillation frequency (f max ) of 66 GHz. - Highlights: • The double plasma process was carried out by two different etching techniques. • Double plasma treated device exhibited a transconductance of 330 mS/mm. • Completed 0.5 μm gate device exhibited a current-gain cutoff frequency of 18 GHz. • The off-state breakdown voltage of 115 V for 0.5 μm gate device was obtained. • Continuous-wave output power density of 4.3 W/mm was obtained at 2.4 GHz

  11. Influence of 60Co gamma radiation on fluorine plasma treated enhancement-mode high-electron-mobility transistor

    Quan Si; Hao Yue; Ma Xiao-Hua; Yu Hui-You

    2011-01-01

    AlGaN/GaN depletion-mode high-electron-mobility transistor (D-HEMT) and fluorine (F) plasma treated enhancement-mode high-electron-mobility transistor (E-HEMT) are exposed to 60 Co gamma radiation with a dose of 1.6 Mrad (Si). No degradation is observed in the performance of D-HEMT. However, the maximum transconductance of E-HEMT is increased after radiation. The 2DEG density and the mobility are calculated from the results of capacitance-voltage measurement. The electron mobility decreases after fluorine plasma treatment and recovers after radiation. Conductance measurements in a frequency range from 10 kHz to 1 MHz are used to characterize the trapping effects in the devices. A new type of trap is observed in the F plasma treated E-HEMT compared with the D-HEMT, but the density of the trap decreases by radiation. Fitting of G p /ω data yields the trap densities D T = (1 − 3) × 10 12 cm −2 · eV −1 and D T = (0.2 − 0.8) × 10 12 cm −2 · eV −1 before and after radiation, respectively. The time constant is 0.5 ms-6 ms. With F plasma treatment, the trap is introduced by etch damage and degrades the electronic mobility. After 60 Co gamma radiation, the etch damage decreases and the electron mobility is improved. The gamma radiation can recover the etch damage caused by F plasma treatment. (interdisciplinary physics and related areas of science and technology)

  12. Magnetotransport of High Mobility Holes in Monolayer and Bilayer WSe2

    Tutuc, Emanuel

    Transition metal dichalcogenides have attracted significant interest because of their two-dimensional crystal structure, large band-gap, and strong spin-orbit interaction which leads to spin-valley locking. Recent advances in sample fabrication have allowed the experimental study of low temperature magneto-transport of high mobility holes in WSe2. We review here the main results of these studies which reveal clear quantum Hall states in mono- and bilayer WSe2. The data allows the extraction of an effective hole mass of m* = 0.45me (me is the bare electron mass) in both mono and bilayer WSe2. A systematic study of the carrier distribution in bilayer WSe2 determined from a Fourier analysis of the Shubnikov-de Haas oscillations indicates that the two layers are weakly coupled. The individual layer density dependence on gate bias shows negative compressibility, a signature of strong electron-electron interaction in these materials associated with the large effective mass. We discuss the interplay between cyclotron and Zeeman splitting using the dependence of the quantum Hall state sequence on carrier density, and the angle between the magnetic field and the WSe2 plane. Work done in collaboration with B. Fallahazad, H. C. P. Movva, K. Kim, S. K. Banerjee, T. Taniguchi, and K. Watanabe. This work supported by the Nanoelectronics Research Initiative SWAN center, Intel Corp., and National Science Foundation.

  13. Isomer Information from Ion Mobility Separation of High-Mannose Glycan Fragments.

    Harvey, David J; Seabright, Gemma E; Vasiljevic, Snezana; Crispin, Max; Struwe, Weston B

    2018-05-01

    Extracted arrival time distributions of negative ion CID-derived fragments produced prior to traveling-wave ion mobility separation were evaluated for their ability to provide structural information on N-linked glycans. Fragmentation of high-mannose glycans released from several glycoproteins, including those from viral sources, provided over 50 fragments, many of which gave unique collisional cross-sections and provided additional information used to assign structural isomers. For example, cross-ring fragments arising from cleavage of the reducing terminal GlcNAc residue on Man 8 GlcNAc 2 isomers have unique collision cross-sections enabling isomers to be differentiated in mixtures. Specific fragment collision cross-sections enabled identification of glycans, the antennae of which terminated in the antigenic α-galactose residue, and ions defining the composition of the 6-antenna of several of the glycans were also found to have different cross-sections from isomeric ions produced in the same spectra. Potential mechanisms for the formation of the various ions are discussed and the estimated collisional cross-sections are tabulated. Graphical Abstract ᅟ.

  14. Redox oscillation affecting mercury mobility from highly contaminated coastal sediments: a mesocosm incubation experiment

    Emili A.

    2013-04-01

    Full Text Available Mercury (Hg mobility at the sediment-water interface was investigated during a laboratory incubation experiment on highly contaminated sediments (up to 23 μg g−1 of the Gulf of Trieste. Undisturbed sediment was collected in front of the Isonzo River mouth, which inflows Hg-rich suspended material originating from the Idrija (NW Slovenia mining district. Since hypoxic and anoxic conditions at the bottom are frequently observed, a redox oscillation was simulated in the laboratory at in situ temperature, using a dark flux chamber. Temporal variations of several parameters were monitored simultaneously: dissolved Hg and methylmercury (MeHg, O2, NH4+, NO3−+NO2−, PO43−, H2S, dissolved Fe and Mn, dissolved inorganic and organic carbon (DIC and DOC. Benthic fluxes of Hg and MeHg were higher under anoxic conditions while re-oxygenation caused concentrations of MeHg and Hg to rapidly drop, probably due to re-adsorption onto Fe/Mn oxyhydroxides and enhanced demethylation. Hence, during anoxic events, sediments of the Gulf of Trieste may be considered as an important source of dissolved Hg species for the water column. However, re-oxygenation of the bottom compartment mitigates Hg and MeHg release from the sediment, thus acting as a natural “defence” from possible interaction between the metal and the aquatic organisms.

  15. A southern African origin and cryptic structure in the highly mobile plains zebra.

    Pedersen, Casper-Emil T; Albrechtsen, Anders; Etter, Paul D; Johnson, Eric A; Orlando, Ludovic; Chikhi, Lounes; Siegismund, Hans R; Heller, Rasmus

    2018-03-01

    The plains zebra (Equus quagga) is an ecologically important species of the African savannah. It is also one of the most numerous and widely distributed ungulates, and six subspecies have been described based on morphological variation. However, the within-species evolutionary processes have been difficult to resolve due to its high mobility and a lack of consensus regarding the population structure. We obtained genome-wide DNA polymorphism data from more than 167,000 loci for 59 plains zebras from across the species range, encompassing all recognized extant subspecies, as well as three mountain zebras (Equus zebra) and three Grevy's zebras (Equus grevyi). Surprisingly, the population genetic structure does not mirror the morphology-based subspecies delineation, underlining the dangers of basing management units exclusively on morphological variation. We use demographic modelling to provide insights into the past phylogeography of the species. The results identify a southern African location as the most likely source region from which all extant populations expanded around 370,000 years ago. We show evidence for inclusion of the extinct and phenotypically divergent quagga (Equus quagga quagga) in the plains zebra variation and reveal that it was less divergent from the other subspecies than the northernmost (Ugandan) extant population.

  16. A compact high resolution ion mobility spectrometer for fast trace gas analysis.

    Kirk, Ansgar T; Allers, Maria; Cochems, Philipp; Langejuergen, Jens; Zimmermann, Stefan

    2013-09-21

    Drift tube ion mobility spectrometers (IMS) are widely used for fast trace gas detection in air, but portable compact systems are typically very limited in their resolving power. Decreasing the initial ion packet width improves the resolution, but is generally associated with a reduced signal-to-noise-ratio (SNR) due to the lower number of ions injected into the drift region. In this paper, we present a refined theory of IMS operation which employs a combined approach for the analysis of the ion drift and the subsequent amplification to predict both the resolution and the SNR of the measured ion current peak. This theoretical analysis shows that the SNR is not a function of the initial ion packet width, meaning that compact drift tube IMS with both very high resolution and extremely low limits of detection can be designed. Based on these implications, an optimized combination of a compact drift tube with a length of just 10 cm and a transimpedance amplifier has been constructed with a resolution of 183 measured for the positive reactant ion peak (RIP(+)), which is sufficient to e.g. separate the RIP(+) from the protonated acetone monomer, even though their drift times only differ by a factor of 1.007. Furthermore, the limits of detection (LODs) for acetone are 180 pptv within 1 s of averaging time and 580 pptv within only 100 ms.

  17. Strontium isotope evidence for a highly mobile population on the Pamir Plateau 2500 years ago

    Wang, Xueye; Tang, Zihua; Wu, Jing; Wu, Xinhua; Wu, Yiqun; Zhou, Xinying

    2016-10-01

    Archeological researches have proposed arguments for human mobility and long-distance trading over the Eurasia before the Silk Roads. Here we utilize biologically available strontium isotope analysis to assess the extent of pre-Silk Road population movements and cultural communications across the Asian interior. From an early Iron Age cemetery (ca. 2500 yr B.P.) on the eastern Pamir Plateau, mean 87Sr/86Sr ratios from 34 individuals display considerable isotopic variability, and 10 individuals are distinguished as migrants based on the local strontium isotope range of 0.710296-0.710572 defined by 12 ovicaprine bones. Comparison of the proportion (10/34) with the regional census data completed in 1909 A.D. (3% non-locals) suggests a highly migratory behavior on the plateau 2500 years ago. Furthermore, exotic mortuary objects, such as silk fabrics from eastern China and angular harp originated from the Near East, clearly demonstrate an interaction between different cultures on the plateau before the establishment of the Silk Road.

  18. Mobile relays for enhanced broadband connectivity in high speed train systems

    Yaacoub, Elias E.

    2014-09-01

    With the introduction of wireless modems and smart phones, the passenger transport industry is witnessing a high demand to ensure not only the safety of the trains, but also to provide users with Internet access all the time inside the train. When the Mobile Terminal (MT) communicates directly with the Base Station (BS), it will experience a severe degradation in the Quality of Service due to the path loss and shadowing effects as the wireless signal is traveling through the train. In this paper, we study the performance in the case of relays placed on top of each train car. In the proposed approach, these relays communicate with the cellular BS on one hand, and with the MTs inside the train cars on the other hand, using the Long Term Evolution (LTE) cellular technology. A low complexity heuristic LTE radio resource management approach is proposed and compared to the Hungarian algorithm, both in the presence and absence of the relays. The presence of the relays is shown to lead to significant enhancements in the effective data rates of the MTs. In addition, the proposed resource management approach is shown to reach a performance close to the optimal Hungarian algorithm. © 2014 Elsevier B.V.

  19. Expression and mechanism of high mobility group box protein-1 in retinal tissue of diabetic rats

    Shuang Jiang

    2016-05-01

    Full Text Available AIM:To investigate the expression and mechanism of high mobility group box protein-1(HMGB1in the retina of diabetic rats. METHODS:Sixty SD rats were randomly divided into diabetic group and control group. Diabetic rat model was produced by intraperitioneal injection of 1% STZ with 60mg/Kg weight. The rats in control group received intraperitioneal injection of normal saline with same dosage. After injection, the rats were sacrificed and eyeballs were enucleated for HE staining, the retina fluorescence angiography, TUNEL and Western Blot detection at 1, 2 and 4mo for the expressions of HMGB1 and NF-κB. RESULTS:Compared with the control group, the retinal cells disorder, cell densities decreases, microvasculars occlusion were founded with inner and outer nuclear layer thinning and ganglion cell apoptosis. The fluorescence angiography showed that peripheral capillaries became circuitous and vascular occlusion and non-perfusion area could be seen. The expressions of HMGB1 and NF-κB were higher than those of control with time dependence and they had significant positive correlations(PCONCLUSION:The expression of HMGB1 increases in diabetic rat retina, which may involve in the occurrence of diabetic retinopathy through the NF- κB pathway.

  20. Density-dependent electron transport and precise modeling of GaN high electron mobility transistors

    Bajaj, Sanyam, E-mail: bajaj.10@osu.edu; Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Reza, Shahed; Chumbes, Eduardo M. [Raytheon Integrated Defense Systems, Andover, Massachusetts 01810 (United States); Khurgin, Jacob [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Material Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-10-12

    We report on the direct measurement of two-dimensional sheet charge density dependence of electron transport in AlGaN/GaN high electron mobility transistors (HEMTs). Pulsed IV measurements established increasing electron velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10{sup 7 }cm/s at a low sheet charge density of 7.8 × 10{sup 11 }cm{sup −2}. An optical phonon emission-based electron velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the electron velocity with strong electron-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.