Science.gov

Sample records for access bandwidth increases

  1. Increasing the quantitative bandwidth of NMR measurements.

    PubMed

    Power, J E; Foroozandeh, M; Adams, R W; Nilsson, M; Coombes, S R; Phillips, A R; Morris, G A

    2016-02-18

    The frequency range of quantitative NMR is increased from tens to hundreds of kHz by a new pulse sequence, CHORUS. It uses chirp pulses to excite uniformly over very large bandwidths, yielding accurate integrals even for nuclei such as (19)F that have very wide spectra.

  2. Bandwidth, Broadband, and Planning for Public Access

    ERIC Educational Resources Information Center

    Blowers, Helene

    2012-01-01

    Broadband and bandwidth allocation is an essential technology planning activity that libraries should address on a continual basis. There are five key factors that will impact your network's performance: 1. infrastructure, 2. network load, 3. workstation performance, 4. prioritization of services, and 5. network management. The author thinks it's…

  3. Novel secure and bandwidth efficient optical code division multiplexed system for future access networks

    NASA Astrophysics Data System (ADS)

    Singh, Simranjit

    2016-12-01

    In this paper, a spectrally coded optical code division multiple access (OCDMA) system using a hybrid modulation scheme has been investigated. The idea is to propose an effective approach for simultaneous improvement of the system capacity and security. Data formats, NRZ (non-return to zero), DQPSK (differential quadrature phase shift keying), and PoISk (polarisation shift keying) are used to get the orthogonal modulated signal. It is observed that the proposed hybrid modulation provides efficient utilisation of bandwidth, increases the data capacity and enhances the data confidentiality over existing OCDMA systems. Further, the proposed system performance is compared with the current state-of-the-art OCDMA schemes.

  4. Shaped optimal control pulses for increased excitation bandwidth in EPR.

    PubMed

    Spindler, Philipp E; Zhang, Yun; Endeward, Burkhard; Gershernzon, Naum; Skinner, Thomas E; Glaser, Steffen J; Prisner, Thomas F

    2012-05-01

    A 1 ns resolution pulse shaping unit has been developed for pulsed EPR spectroscopy to enable 14-bit amplitude and phase modulation. Shaped broadband excitation pulses designed using optimal control theory (OCT) have been tested with this device at X-band frequency (9 GHz). FT-EPR experiments on organic radicals in solution have been performed with the new pulses, designed for uniform excitation over a significantly increased bandwidth compared to a classical rectangular π/2 pulse of the same B(1) amplitude. The concept of a dead-time compensated prefocused pulse has been introduced to EPR with a self-refocusing of 200 ns after the end of the pulse. Echo-like refocused signals have been recorded and compared to the performance of a classical Hahn-echo sequence. The impulse response function of the microwave setup has been measured and incorporated into the algorithm for designing OCT pulses, resulting in further significant improvements in performance. Experimental limitations and potential new applications of OCT pulses in EPR spectroscopy will be discussed.

  5. Method and device for maximizing memory system bandwidth by accessing data in a dynamically determined order

    NASA Technical Reports Server (NTRS)

    Wulf, William A. (Inventor); McKee, Sally A. (Inventor); Klenke, Robert (Inventor); Schwab, Andrew J. (Inventor); Moyer, Stephen A. (Inventor); Aylor, James (Inventor); Hitchcock, Charles Young (Inventor)

    2000-01-01

    A data processing system is disclosed which comprises a data processor and memory control device for controlling the access of information from the memory. The memory control device includes temporary storage and decision ability for determining what order to execute the memory accesses. The compiler detects the requirements of the data processor and selects the data to stream to the memory control device which determines a memory access order. The order in which to access said information is selected based on the location of information stored in the memory. The information is repeatedly accessed from memory and stored in the temporary storage until all streamed information is accessed. The information is stored until required by the data processor. The selection of the order in which to access information maximizes bandwidth and decreases the retrieval time.

  6. The Benefits of Increased Sensation Level and Bandwidth for Spatial Release From Masking

    PubMed Central

    Kampel, Sean D.; Gordon, Samuel Y.; Gallun, Frederick J.

    2017-01-01

    Objective: Spatial release from masking (SRM) can increase speech intelligibility in complex listening environments. The goal of the present study was to document how speech-in-speech stimuli could be best processed to encourage optimum SRM for listeners who represent a range of ages and amounts of hearing loss. We examined the effects of equating stimulus audibility among listeners, presenting stimuli at uniform sensation levels (SLs), and filtering stimuli at two separate bandwidths. Design: Seventy-one participants completed two speech intelligibility experiments (36 listeners in experiment 1; all 71 in experiment 2) in which a target phrase from the coordinate response measure (CRM) and two masking phrases from the CRM were presented simultaneously via earphones using a virtual spatial array, such that the target sentence was always at 0 degree azimuth angle and the maskers were either colocated or positioned at ±45 degrees. Experiments 1 and 2 examined the impacts of SL, age, and hearing loss on SRM. Experiment 2 also assessed the effects of stimulus bandwidth on SRM. Results: Overall, listeners’ ability to achieve SRM improved with increased SL. Younger listeners with less hearing loss achieved more SRM than older or hearing-impaired listeners. It was hypothesized that SL and bandwidth would result in dissociable effects on SRM. However, acoustical analysis revealed that effective audible bandwidth, defined as the highest frequency at which the stimulus was audible at both ears, was the best predictor of performance. Thus, increasing SL seemed to improve SRM by increasing the effective bandwidth rather than increasing the level of already audible components. Conclusions: Performance for all listeners, regardless of age or hearing loss, improved with an increase in overall SL and/or bandwidth, but the improvement was small relative to the benefits of spatial separation. PMID:27556520

  7. Virtual queueing techniques for UBR+ service in ATM with fair access and minimum bandwidth guarantee

    SciTech Connect

    Siu, K.Y.; Wu, Y.; Ren, W.

    1998-11-01

    The ATM Forum is currently discussing the need for a new best-effort service called UBR+, which is an enhancement to the existing UBR service, to support data traffic. The objective of the UBR+ service is to provide each user with a minimum service rate guarantee and a fair access to any excess available bandwidth. In this paper, the authors present a new efficient scheme for supporting this service. The key advantage of the scheme is that it employs only FIFO queueing (instead of per-VC queueing) and admits simple implementation in ATM switches. The ideas involve a simple scheduling mechanism that is based on per-VC queueing and incorporate the virtual queueing technique that can efficiently emulate per-VC queueing on a shared FIFO queue. Simulation results are presented to show that the schemes can deliver almost ideal performance for supporting the new service requirements of UBR+.

  8. Super-linear modulator with extended bandwidth capability for broadband access applications

    NASA Astrophysics Data System (ADS)

    Prescod, Andru; Dingel, Benjamin B.; Madamopoulos, Nicholas

    2009-01-01

    Ultra-linear modulators are critical components for broadband access applications in analog fiber-optic communication links, such as Radio-over-Fiber (RoF), Radio-over-Free Space (RoFS) and ultra-dense (cable television) CATV. In our previous work, it was shown that an ultra-linear optical modulator - composed of a phase modulator and ring resonator in a Mach-Zehnder (MZ) configuration, exhibited SFDR values > 130 dB. In this paper, we introduce a new configuration based on a lumped electrode design, in which the phase modulator (PM) is on one arm of the MZ and the ring resonator (RR) is located on the other arm. We also carefully control and monitor the power split ratio of an RF input to both the PM and the RR, in addition to the RF phase bias between the RR and PM. We report its unique and superior features such as superior linearity (SFDR ~ 133 dB), modulation bandwidth extension (as much as 70%) over the ring resonator-assisted Mach Zehnder design and high link gain. Lastly, we discuss the merits of the design flexibility, practicality and ease of use of the new modulator.

  9. Surface plasmon bandwidth increase using chirped-pitch linear diffraction gratings.

    PubMed

    Bailey, Erin; Sabat, Ribal Georges

    2017-03-20

    Large-scale linear diffraction gratings with gradually varying pitch were photo-inscribed onto the surface of azobenzene thin films using a 532 nm laser and a modified Lloyd mirror set-up. By placing a cylindrical lens in front of the direct half of the inscribing beam, gratings with a chirping rate as high as 12.9 nm/mm were produced. Subsequently, when these chirped-pitch gratings were coated with silver, over three-fold bandwidth increase was observed in the surface plasmon transmission peaks at FWHM, when compared to constant-pitch gratings. This was made possible due to the simultaneous excitation of surface plasmon resonance in a band of light wavelengths.

  10. Dynamic pressure sensor calibration techniques offering expanded bandwidth with increased resolution

    NASA Astrophysics Data System (ADS)

    Wisniewiski, David

    2015-03-01

    Advancements in the aerospace, defense and energy markets are being made possible by increasingly more sophisticated systems and sub-systems which rely upon critical information to be conveyed from the physical environment being monitored through ever more specialized, extreme environment sensing components. One sensing parameter of particular interest is dynamic pressure measurement. Crossing the boundary of all three markets (i.e. aerospace, defense and energy) is dynamic pressure sensing which is used in research and development of gas turbine technology, and subsequently embedded into a control loop used for long-term monitoring. Applications include quantifying the effects of aircraft boundary layer ingestion into the engine inlet to provide a reliable and robust design. Another application includes optimization of combustor dynamics by "listening" to the acoustic signature so that fuel-to-air mixture can be adjusted in real-time to provide cost operating efficiencies and reduced NOx emissions. With the vast majority of pressure sensors supplied today being calibrated either statically or "quasi" statically, the dynamic response characterization of the frequency dependent sensitivity (i.e. transfer function) of the pressure sensor is noticeably absent. The shock tube has been shown to be an efficient vehicle to provide frequency response of pressure sensors from extremely high frequencies down to 500 Hz. Recent development activity has lowered this starting frequency; thereby augmenting the calibration bandwidth with increased frequency resolution so that as the pressure sensor is used in an actual test application, more understanding of the physical measurement can be ascertained by the end-user.

  11. Apparatus and method for increasing the bandwidth of a laser beam

    DOEpatents

    Chaffee, Paul H.

    1991-01-01

    A method and apparatus is disclosed that provides a laser output beam having a broad bandwidth and an intensity smooth over time. The bandwidth of the laser output can be varied easily by varying the intensity of a broadband source. The present invention includes an optical modulation apparatus comprising a narrowband laser that outputs a horizontally polarized beam (a "signal beam") and a broadband laser that outputs a vertically polarized beam (a "pump beam") whose intensity varies rapidly. The two beam are coupled into a birefringent laser material so that the respective polarizations coincide with the principal axes of the material. As the two beams travel through the material, the polarization preserving properties of the birefringent material maintain the respective polarizations of the two beam; however there is coupling between the two beams as a result of cross phase modulations, which induces a bandwidth change of the signal beam. The amount of bandwidth change is dependent upon the average intensity of the pump beam. The beams are coupled out from the birefringent material and the modulated signal beam is separated by a polarization selector. The modulated signal beam now has a wider bandwidth, and its shape remains smooth in time. This signal beam can be applied to incoherence inducing systems. The different bandwidths required by these different incoherence inducing systems can be obtained by varying the intensity of the pump beam. The United States Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  12. Accessing Geospatial Services in Limited Bandwidth Service-Oriented Architecture (SOA) Environments

    ERIC Educational Resources Information Center

    Boggs, James D.

    2013-01-01

    First responders are continuously moving at an incident site and this movement requires them to access Service-Oriented Architecture services, such as a Web Map Service, via mobile wireless networks. First responders from inside a building often have problems in communicating to devices outside that building due to propagation obstacles. Dynamic…

  13. Bandwidth-allocated algorithm modeled with matrix theory for traffic-orientated multisubsystem-based virtual passive optical network in metro-access optical network

    NASA Astrophysics Data System (ADS)

    Xia, Weidong; Gan, Chaoqin; Chen, Bingqin; Xie, Weilun; Zhang, YuChao; Gou, Kaiyu

    2016-09-01

    In a metro-access optical network, a bandwidth-allocated algorithm is proposed for traffic-orientated multisubsystem-based virtual passive optical network (MS-VPON) that can implement the syncretism of multiple systems such as time division multiplexing-PON (TDM-PON), wavelength division multiplexing-PON (WDM-PON), and orthogonal frequency division multiplexing-PON (OFDM-PON). VPONs are constructed based on traffic and different VPONs are separated by different types of traffic. The bandwidth-allocated algorithm is modeled with a matrix theory to determine which VPON can be admitted and then a bandwidth is assigned to these VPONs. With the algorithm, the network value can be maximized. Two cases are investigated to demonstrate the effectiveness of the proposed algorithm in the bandwidth-utilized ratio and VPONs' admission probability.

  14. Holographic display system for dynamic synthesis of 3D light fields with increased space bandwidth product.

    PubMed

    Agour, Mostafa; Falldorf, Claas; Bergmann, Ralf B

    2016-06-27

    We present a new method for the generation of a dynamic wave field with high space bandwidth product (SBP). The dynamic wave field is generated from several wave fields diffracted by a display which comprises multiple spatial light modulators (SLMs) each having a comparably low SBP. In contrast to similar approaches in stereoscopy, we describe how the independently generated wave fields can be coherently superposed. A major benefit of the scheme is that the display system may be extended to provide an even larger display. A compact experimental configuration which is composed of four phase-only SLMs to realize the coherent combination of independent wave fields is presented. Effects of important technical parameters of the display system on the wave field generated across the observation plane are investigated. These effects include, e.g., the tilt of the individual SLM and the gap between the active areas of multiple SLMs. As an example of application, holographic reconstruction of a 3D object with parallax effects is demonstrated.

  15. Apparatus and method for increasing the bandwidth of a laser beam

    DOEpatents

    Wilcox, Russell B.

    1992-01-01

    A method and apparatus using sinusoidal cross-phase modulation, provides a laser pulse having a very broad bandwidth while substantially retaining the input laser's temporal shape. The modulator may be used in a master oscillator system for a laser having a master oscillator-power amplifier (MOPA) configration. The modulator utilizes a first laser providing an output wavelength .lambda. and a second laser providing an output wavelength shifted by a small amount to .lambda.+.DELTA..lambda.. Each beam has a single, linear polarization. Each beam is coupled into a length of polarization-preserving optical fiber. The first laser beam is coupled into the optical fiber with the beam's polarization aligned with the fiber's main axis, and the second beam is coupled into the fiber with its polarization rotated from the main axis by a predetermined angle. Within the fiber, the main axis' polarization defines an interference beam and the orthogonal axis' polarization defines a signal beam. In the interference beam, the first laser beam and the parallel polarized vector component of the other beam interfere to create areas of high and low intensity, which modulates the signal beam by cross phase modulation. Upon exit from the optical fiber, the beams are coupled out and the modulated signal beam is separated out by a polarization selector. The signal beam can be applied to coherence reducing systems to provide an output that is temporally and spatially incoherent. The U.S. Government has rights in this invention pursuant to Contract No. W7405-ENG-48 between the U.S. Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.

  16. Synthesis and demonstration of high speed, bandwidth efficient optical Code Division Multiple Access (CDMA) tested at 1 Gb/s throughput

    NASA Astrophysics Data System (ADS)

    Mendez, Antonio J.; Lambert, James L.; Morookian, John-Michael; Gagliardi, Robert M.

    1994-09-01

    Code division multiple access (CDMA) permits concurrent communication over all virtual channels (in principle), independent of the data rate and the network size. In reality, most CDMA approaches have a bandwidth penalty due to the code length and a loss penalty due to the broadcasting required by CDMA. Both of these penalties can be reduced or ameliorated by means of multi-attribute coding. Matrices constructed from relatively inefficient (0, 1)pulse sequences are suitable multi-attribute non-coherent CDMA codes which are both bandwidth and broadcast efficient. We exhibit a novel approach to synthesizing matrix CDMA codes, develop a 4 x 4 physical model, and demonstrate concurrent communication experimentally at concurrent data rates of 100-, 150-, and 250 Mb/s per port.

  17. Dressing the chopped-random-basis optimization: A bandwidth-limited access to the trap-free landscape

    NASA Astrophysics Data System (ADS)

    Rach, N.; Müller, M. M.; Calarco, T.; Montangero, S.

    2015-12-01

    In quantum optimal control theory the success of an optimization algorithm is highly influenced by how the figure of merit to be optimized behaves as a function of the control field, i.e., by the control landscape. Constraints on the control field introduce local minima in the landscape—false traps—which might prevent an efficient solution of the optimal control problem. Rabitz et al. [Science 303, 1998 (2004), 10.1126/science.1093649] showed that local minima occur only rarely for unconstrained optimization. Here, we extend this result to the case of bandwidth-limited control pulses showing that in this case one can eliminate the false traps arising from the constraint. Based on this theoretical understanding, we modify the chopped-random-basis (CRAB) optimal control algorithm and show that this development exploits the advantages of both (unconstrained) gradient algorithms and of truncated basis methods, allowing one to always follow the gradient of the unconstrained landscape by bandwidth-limited control functions. We study the effects of additional constraints and show that for reasonable constraints the convergence properties are still maintained. Finally, we numerically show that this approach saturates the theoretical bound on the minimal bandwidth of the control needed to optimally drive the system.

  18. Got Bandwidth?

    ERIC Educational Resources Information Center

    Villano, Matt

    2009-01-01

    Video-heavy distance learning programs can put a strain on the campus network. This article describes how three institutions are managing bandwidth to ensure high-quality service for eLearning students.

  19. SU-E-I-62: Reduction of Susceptibility Artifacts by Increasing the Bandwidth (BW) and Echo Train Length (ETL)

    SciTech Connect

    Mavroidis, P; Boci, N; Kostopoulos, S; Ninos, C; Glotsos, D; Oikonomou, G; Bakas, A; Roka, V; Cavouras, D; Lavdas, E; Sakkas, G; Tsagkalis, A; Chatzivasileiou, V; Batsikas, G; Papanikolaou, N; Stathakis, S

    2015-06-15

    Purpose: The aim of this present study is to increase bandwidth (BW) and echo train length (ETL) in Proton Density Turbo Spin Echo (PD TSE) sequences with and without fat saturation (FS) as well as in Turbo Inversion Recovery Magnitude sequences (TIRM) in order to assess whether these sequences are capable of reducing susceptibility artifacts. Methods: We compared 1) TIRM coronal (COR) with the same sequence with increased both BW and ETL 2) Conventional PD TSE sagittal (SAG) with FS with an increased BW 3) Conventional PD TSE SAG without FS with an increased BW 4) Conventional PD TSE SAG without FS with increased both BW and ETL. A quantitative analysis was performed to measure the extent of the susceptibility artifacts. Furthermore, a qualitative analysis was performed by two radiologists in order to evaluate the susceptibility artifacts, image distortion and fat suppression. The depiction of cartilage, menisci, muscles, tendons and bone marrow were also qualitatively analyzed. Results: The quantitative analysis found that the modified TIRM sequence is significantly superior to the conventional one regarding the extent of the susceptibility artifacts. In the qualitative analysis, the modified TIRM sequence was superior to the corresponding conventional one in eight characteristics out of ten that were analyzed. The modified PD TSE with FS was superior to the corresponding conventional one regarding the susceptibility artifacts, image distortion and depiction of bone marrow and cartilage while achieving effective fat saturation. The modified PD TSE sequence without FS with a high (H) BW was found to be superior corresponding to the conventional one in the case of cartilage. Conclusion: Consequently, TIRM sequence with an increased BW and ETL is proposed for producing images of high quality and modified PD TSE with H BW for smaller metals, especially when FS is used.

  20. Accelerated Recovery of Consciousness after General Anesthesia Is Associated with Increased Functional Brain Connectivity in the High-Gamma Bandwidth

    PubMed Central

    Li, Duan; Hambrecht-Wiedbusch, Viviane S.; Mashour, George A.

    2017-01-01

    Recent data from our laboratory demonstrate that high-frequency gamma connectivity across the cortex is present during consciousness and depressed during unconsciousness. However, these data were derived from static and well-defined states of arousal rather than during transitions that would suggest functional relevance. We also recently found that subanesthetic ketamine administered during isoflurane anesthesia accelerates recovery upon discontinuation of the primary anesthetic and increases gamma power during emergence. In the current study we re-analyzed electroencephalogram (EEG) data to test the hypothesis that functional cortical connectivity between anterior and posterior cortical regions would be increased during accelerated recovery induced by ketamine when compared to saline-treated controls. Rodents were instrumented with intracranial EEG electrodes and general anesthesia was induced with isoflurane anesthesia. After 37.5 min of continuous isoflurane anesthesia, a subanesthetic dose of ketamine (25 mg/kg intraperitoneal) was administered, with evidence of a 44% reduction in emergence time. In this study, we analyzed gamma and theta coherence (measure of undirected functional connectivity) and normalized symbolic transfer entropy (measure of directed functional connectivity) between frontal and parietal cortices during various levels of consciousness, with a focus on emergence from isoflurane anesthesia. During accelerated emergence in the ketamine-treated group, there was increased frontal-parietal coherence {p = 0.005, 0.05–0.23 [95% confidence interval (CI)]} and normalized symbolic transfer entropy [frontal to parietal: p < 0.001, 0.010–0.026 (95% CI); parietal to frontal: p < 0.001, 0.009–0.025 (95% CI)] in high-frequency gamma bandwidth as compared with the saline-treated group. Surrogates of cortical information exchange in high-frequency gamma are increased in association with accelerated recovery from anesthesia. This finding adds evidence

  1. Combined Effect of Reduced Band Number and Increased Bandwidth on Shallow Water Remote Sensing: The Case of WorldView 2

    DTIC Science & Technology

    2013-05-01

    on Shallow Water Remote Sensing : The Case of WorldView 2 N/A NNH09AM26I 73-4223-01-5 ZhongPing Lee, Alan Weidemann, and Robert Arnone Naval Research...Presentation The Combined Effect of Reduced Spectral Bands and Increased Bandwidth on Shallow Water Remote Sensing : The Case of WorldView 2...ON GEOSCIENCE AND REMOTE SENSING , VOL. 51, NO. 5, MAY 2013 2577 Combined Effect of Reduced Band Number and Increased Bandwidth on Shallow Water Remote

  2. Electrical Spreading Code-Based OFDM Optical Access Networks for Budget Enhancement and Reduced System Bandwidth Requirement

    NASA Astrophysics Data System (ADS)

    Kumar, Pravindra; Srivastava, Anand

    2015-12-01

    Passive optical networks based on orthogonal frequency division multiplexing (OFDM-PON) give better performance in high-speed optical access networks. For further improvement in performance, a new architecture of OFDM-PON based on spreading code in electrical domain is proposed and analytically analyzed in this paper. This approach is referred as hybrid multi-carrier code division multiple access-passive optical network (MC-CDMA-PON). Analytical results show that at bit error rate (BER) of 10-3, there is 9.4 dB and 14.2 dB improvement in optical power budget for downstream and upstream, respectively, with MC-CDMA-PON system as compared to conventional OFDM-PON system for the same number of optical network units (ONUs).

  3. Expanding Dual Enrollment: Increasing Postsecondary Access for All?

    ERIC Educational Resources Information Center

    Pretlow, Josh; Wathington, Heather D.

    2014-01-01

    This study investigated the dual enrollment outcomes associated with a 2005 policy change intended to expand dual enrollment participation in Virginia. Results indicated that overall access to and participation in dual enrollment courses increased following the policy change. However, data showed this increase was not uniform, and minority groups…

  4. Service composition towards increasing end-user accessibility.

    PubMed

    Kaklanis, Nikolaos; Votis, Konstantinos; Tzovaras, Dimitrios

    2015-01-01

    This paper presents the Cloud4all Service Synthesizer Tool, a framework that enables efficient orchestration of accessibility services, as well as their combination into complex forms, providing more advanced functionalities towards increasing the accessibility of end-users with various types of functional limitations. The supported services are described formally within an ontology, enabling, thus, semantic service composition. The proposed service composition approach is based on semantic matching between services specifications on the one hand and user needs/preferences and current context of use on the other hand. The use of automatic composition of accessibility services can significantly enhance end-users' accessibility, especially in cases where assistive solutions are not available in their device.

  5. Outcomes of Increased Access to Postsecondary Education by Deaf Persons.

    ERIC Educational Resources Information Center

    Walter, Gerard G.

    This assessment of the outcomes of increased access to postsecondary education for hearing-impaired students focuses on attrition levels and earnings levels. To analyze attrition from postsecondary programs serving the deaf, information from 95 programs was gathered. Using an algorithm to estimate cohort survival rates and taking into account…

  6. Playing prosocial video games increases the accessibility of prosocial thoughts.

    PubMed

    Greitemeyer, Tobias; Osswald, Silvia

    2011-01-01

    Past research has provided abundant evidence that playing violent video games increases aggressive tendencies. In contrast, evidence on possible positive effects of video game exposure on prosocial tendencies has been relatively sparse. The present research tested and found support for the hypothesis that exposure to prosocial video games increases the accessibility of prosocial thoughts. These results provide support to the predictive validity of the General Learning Model (Buckley & Anderson, 2006) for the effects of exposure to prosocial media on social tendencies. Thus, depending on the content of the video game, playing video games can harm but may also benefit social relations.

  7. Increasing access and support for emergency management higher education programs.

    PubMed

    Cwiak, Carol L

    2014-01-01

    The number of emergency management higher education programs has grown dramatically since 1994 when the FEMA Higher Education Program was created to propagate and support such growth. Data collected annually since 2007 from emergency management higher education programs shows that these programs face some consistent challenges. These challenges were coupled with annual data on program access and support indicators via dimensional analysis to answer the questions: To what extent are the challenges linked to a lack of access or support? If there is linkage, what can be gleaned from these linkages that can help address the challenges through improving access and support? The analysis showed that lack of access to funding and resources, and lack of support from partner organizations, has an impact on emergency management higher education. Discussion of that impact is followed with detailed recommendations that are focused on strengthening both internal and external access and support relationships for emergency management higher education programs.

  8. Increasing Ocean Access to Totten Glacier, East Antarctica

    NASA Astrophysics Data System (ADS)

    Greenbaum, J. S.; Blankenship, D. D.; Young, D. A.; Aitken, A.; Richter, T. G.; Roberts, J. L.; Warner, R. C.; van Ommen, T. D.; Siegert, M. J.

    2014-12-01

    The Totten Glacier Ice Shelf (TGIS) is the primary outlet of the Aurora Subglacial Basin, draining 6.9 meters of eustatic sea level potential into the Sabrina Coast (SC) alongside the Moscow University Ice Shelf that fringes the coastline. The TGIS and surrounding grounded ice has the largest thinning signal in East Antarctica and the nature of the thinning suggests that it is driven by enhanced basal melting due to ocean processes. Warm Modified Circumpolar Deep Water (MCDW), which has been linked to glacier retreat in West Antarctica, has been observed in summer and winter on the SC continental shelf in the 400-500 m depth range. Here we show, using new data from recent aerogeophysical flights, that entrances to the cavity exist that are deeper than this range of thermocline depths, indicating that the TGIS is vulnerable to intrusions of MCDW if the vertical structure of cavity inflow is similar to the nearest observations. We provide evidence that a new entry to the cavity has opened likely due to the interplay between thinning ice and subglacial channels that could be related to regional mass loss acceleration observed in 2006. This new connection may increase access of warm water to the east side of the ice shelf, potentially destabilizing the low-lying area to the east of the TGIS.

  9. Combining spatial domain multiplexing and orbital angular momentum of photon-based multiplexing to increase the bandwidth of optical fiber communication systems

    NASA Astrophysics Data System (ADS)

    Murshid, Syed; Alanzi, Saud; Hridoy, Arnob; Lovell, Gregory L.; Parhar, Gurinder; Chakravarty, Abhijit; Chowdhury, Bilas

    2016-06-01

    Spatial domain multiplexing/space division multiplexing (SDM) can increase the bandwidth of existing and futuristic optical fibers by an order of magnitude or more. In the SDM technique, we launch multiple single-mode pigtail laser sources of the same wavelength into a carrier multimode fiber at different angles. The launching angles decide the output of the carrier fiber by allocating separate spatial locations for each channel. Each channel follows a helical trajectory while traversing the length of the carrier fiber, thereby allowing spatial reuse of optical frequencies. We launch light from five different single-mode pigtail laser sources (of same wavelength) at different angles (with respect to the axis of the carrier fiber) into the carrier fiber. Owing to helical propagation, five distinct concentric donut-shaped rings with negligible crosstalk at the output end of the fiber were obtained. These SDM channels also exhibit orbital angular momentum (OAM), thereby adding an extradegree of photon freedom. We present the experimental data of five spatially multiplexed channels and compare them with simulated results to show that this technique can potentially improve the data capacity of optical fibers by an order of magnitude: A factor of five using SDM and another factor of two using OAM.

  10. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-05-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  11. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan; Jersey Inst Ansari, New; Jersey Inst, New

    2005-04-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  12. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-06-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  13. Network Bandwidth Utilization Forecast Model on High Bandwidth Network

    SciTech Connect

    Yoo, Wucherl; Sim, Alex

    2014-07-07

    With the increasing number of geographically distributed scientific collaborations and the scale of the data size growth, it has become more challenging for users to achieve the best possible network performance on a shared network. We have developed a forecast model to predict expected bandwidth utilization for high-bandwidth wide area network. The forecast model can improve the efficiency of resource utilization and scheduling data movements on high-bandwidth network to accommodate ever increasing data volume for large-scale scientific data applications. Univariate model is developed with STL and ARIMA on SNMP path utilization data. Compared with traditional approach such as Box-Jenkins methodology, our forecast model reduces computation time by 83.2percent. It also shows resilience against abrupt network usage change. The accuracy of the forecast model is within the standard deviation of the monitored measurements.

  14. Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

    PubMed Central

    Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

    2017-01-01

    Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide. PMID:28071681

  15. Increased impedance near cut-off in plasma-like media leading to emission of high-power, narrow-bandwidth radiation

    NASA Astrophysics Data System (ADS)

    Hur, M. S.; Ersfeld, B.; Noble, A.; Suk, H.; Jaroszynski, D. A.

    2017-01-01

    Ultra-intense, narrow-bandwidth, electromagnetic pulses have become important tools for exploring the characteristics of matter. Modern tuneable high-power light sources, such as free-electron lasers and vacuum tubes, rely on bunching of relativistic or near-relativistic electrons in vacuum. Here we present a fundamentally different method for producing narrow-bandwidth radiation from a broad spectral bandwidth current source, which takes advantage of the inflated radiation impedance close to cut-off in a medium with a plasma-like permittivity. We find that by embedding a current source in this cut-off region, more than an order of magnitude enhancement of the radiation intensity is obtained compared with emission directly into free space. The method suggests a simple and general way to flexibly use broadband current sources to produce broad or narrow bandwidth pulses. As an example, we demonstrate, using particle-in-cell simulations, enhanced monochromatic emission of terahertz radiation using a two-colour pumped current source enclosed by a tapered waveguide.

  16. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-03-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  17. Bandwidth requirements for fine resolution squinted SAR

    SciTech Connect

    DOERRY,ARMIN W.

    2000-03-01

    The conventional rule-of-thumb for Synthetic Aperture Radar is that an RF bandwidth of c/(2{rho}{sub r}) is required to image a scene at the desired slant-range resolution {rho}{sub r}, and perhaps a little more to account for window functions and sidelobe control. This formulation is based on the notion that the total bandwidth required is the same bandwidth that is required for a single pulse. What is neglected is that efficient processing of an entire synthetic aperture of pulses will often require different frequency content for each of the different pulses that makeup a synthetic aperture. Consequently, the total RF bandwidth required of a Synthetic Aperture Radar may then be substantially wider than the bandwidth of any single pulse. The actual RF bandwidth required depends strongly on flight geometry, owing to the desire for a radar to maintain a constant projection of the Fourier space collection surface onto the {omega}{sub y} axis. Long apertures required for fine azimuth resolution, and severe squint angles with steep depression angles may require total RF bandwidths well beyond the minimum bandwidth required of any single transmitted pulse, perhaps even by a factor of two or more. Accounting for this is crucial to designing efficient versatile high-performance imaging radars. This paper addresses how a data set conducive to efficient processing might increase the total RF bandwidth, and presents examples of how a fixed RF bandwidth might then limit SAR geometries.

  18. Developing Strategies for Affordable Bandwidth.

    ERIC Educational Resources Information Center

    Educause Quarterly, 2000

    2000-01-01

    Written by Educause's Net@EDU Broadband Pricing Working Group, this article discusses what institutions of higher education can do to develop good partnerships with broadband vendors in order to negotiate affordable pricing for increased bandwidth. Describes problems with the marketplace, examples from a few universities, and points to remember…

  19. Increasing Access to Health Care Providers with Nurse Practitioner Competencies

    ERIC Educational Resources Information Center

    Grace, Del Marjorie

    2014-01-01

    Emergency department visits increased from 102.8 million to 136.1 million in 2009, resulting in crowding and increased wait times, affecting U.S. hospitals' ability to provide safe, timely patient care resulting in dangerous delays and serious health problems shown by research. The purpose of this project was to determine if competencies developed…

  20. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-02-01

    Call for Papers: Optical Access Networks With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the economic viability of many potential high-bandwidth applications. In recent years, optical access networks have been receiving tremendous attention from both academia and industry. A large number of research activities have been carried out or

  1. Increasing access by priority populations to Australian sexual health clinics.

    PubMed

    Ali, Hammad; Donovan, Basil; Fairley, Christopher K; Chen, Marcus Y; O'Connor, Catherine C; Grulich, Andrew E; McNulty, Anna; Ryder, Nathan; Hellard, Margaret E; Guy, Rebecca J

    2013-10-01

    Data from a network of 35 Australian sexual health clinics, in geographically diverse locations, showed that the number and proportion of patients from priority populations (ie, young people, men who have sex with men, indigenous people, and female sex workers) increased significantly between 2004 and 2011.

  2. Directing Traffic: Managing Internet Bandwidth Fairly

    ERIC Educational Resources Information Center

    Paine, Thomas A.; Griggs, Tyler J.

    2008-01-01

    Educational institutions today face budgetary restraints and scarce resources, complicating the decision of how to allot bandwidth for campus network users. Additionally, campus concerns over peer-to-peer networking (specifically outbound Internet traffic) have increased because of bandwidth and copyright issues. In this article, the authors…

  3. Chemical Industry Bandwidth Study

    SciTech Connect

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  4. A Quest for Bandwidth.

    ERIC Educational Resources Information Center

    Nye, Steve

    2002-01-01

    Describes how Portland State University brought broadband into its older residence halls using Long-Reach Ethernet, a technology that delivers high bandwidth across the unconditioned telephone-grade wire that already existed in the buildings. (EV)

  5. Glass Industry Bandwidth Analysis

    SciTech Connect

    Rue, David M.

    2006-07-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  6. Industrial Glass Bandwidth Analysis

    SciTech Connect

    Rue, David M.; Servaites, James; Wolf, Warren

    2007-08-01

    This is a study on energy use and potential savings, or "bandwidth" study, for several glassmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results.

  7. Intermittent access to a sucrose solution for rats causes long-term increases in consumption.

    PubMed

    Eikelboom, Roelof; Hewitt, Randelle

    2016-10-15

    Intermittent access to palatable food can elevate consumption beyond an animal's immediate needs. If adult male rats (with ad lib access to food and water) are provided with a 4% sucrose solution, daily sucrose consumption is determined by the sucrose access schedule: access that is intermittent leads to high levels of consumption. In Experiment 1, sucrose solutions were first provided continuously or every second, third, or fourth day for 23.5h over 49days. Continuous-access sucrose consumption averaged 102g per day, while that for access every fourth day averaged 294g. Daily consumption averages for access every second and third day fell between these two extremes. When all rats were then given alternate-day access to sucrose for 24days in Phase II, the previously established consumption differences were maintained. Body weight was unaffected by sucrose access; rats adjusted their food consumption so that total calorie intake remained constant. In Experiment 2, compared to continuous 4% sucrose solution access, access every third day markedly elevated daily sucrose consumption after only four sucrose exposures. With this shorter Phase I, sucrose intake in the continuous group increased markedly when in Phase II all rats were given alternate day access. In Experiment 3, a lick-by-lick analysis of the difference in sucrose consumption between access every third day and continuous access revealed that all rats were consuming a similar number of sucrose meals; however, the meals were larger both in the first hour and over the whole 24h with intermittent access. This suggests a change in satiety as a mechanism underlying sucrose consumption difference.

  8. Creating a Public Domain Software Library To Increase Computer Access of Elementary Students with Learning Disabilities.

    ERIC Educational Resources Information Center

    McInturff, Johanna R.

    Information is provided on a practicum that addressed the lack of access to computer-aided instruction by elementary level students with learning disabilities, due to lack of diverse software, limited funding, and insufficient teacher training. The strategies to improve the amount of access time included: increasing the number of computer programs…

  9. Breaking inertia: increasing access to journals during a period of declining budgets: a case study

    PubMed Central

    Fought, Rick L.

    2014-01-01

    Beginning in January 2012, a 1-year pilot pay-per-view (PPV) service was implemented. Twenty-four journal subscriptions were canceled to fund the service, and through the PPV service, the library was able to offer patrons access to over 700 previously unavailable biomedical journals. At the end of the pilot period, the total PPV cost for each journal accessed was compared to the subscription cost to determine if PPV was an effective use of library money. While remaining essentially budget neutral, the number of full-text articles accessed increased over 400%. PPV can be a cost-effective method for expanding access to journals. PMID:25031560

  10. Breaking inertia: increasing access to journals during a period of declining budgets: a case study.

    PubMed

    Fought, Rick L

    2014-07-01

    Beginning in January 2012, a 1-year pilot pay-per-view (PPV) service was implemented. Twenty-four journal subscriptions were canceled to fund the service, and through the PPV service, the library was able to offer patrons access to over 700 previously unavailable biomedical journals. At the end of the pilot period, the total PPV cost for each journal accessed was compared to the subscription cost to determine if PPV was an effective use of library money. While remaining essentially budget neutral, the number of full-text articles accessed increased over 400%. PPV can be a cost-effective method for expanding access to journals.

  11. Decreased Cancer Mortality-to-Incidence Ratios with Increased Accessibility of Federally Qualified Health Centers

    PubMed Central

    Adams, Swann Arp; Choi, Seul Ki; Khang, Leepao; Campbell, Dayna A.; Friedman, Daniela B.; Eberth, Jan M.; Glasgow, Russell E.; Tucker-Seeley, Reginald; Xirasagar, Sudha; Yip, Mei Po; Young, Vicki M.; Hébert, James R.

    2015-01-01

    Federally qualified health centers (FQHCs) offer primary and preventive healthcare, including cancer screening, for the nation’s most vulnerable population. The purpose of this study was to explore the relationship between access to FQHCs and cancer mortality-to-incidence ratios (MIRs). One-way analysis of variance was conducted to compare the mean MIRs for breast, cervical, prostate, and colorectal cancers for each U.S. county for 2006–2010 by access to FQHCs (direct access, in-county FQHC; indirect access, adjacent-county FQHC; no access, no FQHC either in the county or in adjacent counties). ArcMap 10.1 software was used to map cancer MIRs and FQHC access levels. The mean MIRs for breast, cervical, and prostate cancer differed significantly across FQHC access levels (p < 0.05). In urban and healthcare professional shortage areas, mean MIRs decreased as FQHC access increased. A trend of lower breast and prostate cancer MIRs in direct access to FQHCs was found for all racial groups, but this trend was significant for whites only. States with a large proportion of rural and medically underserved areas had high mean MIRs, with correspondingly more direct FQHC access. Expanding FQHCs to more underserved areas and concentrations of disparity populations may have an important role in reducing cancer morbidity and mortality, as well as racial-ethnic disparities, in the United States. PMID:25634545

  12. Low-bandwidth authentication.

    SciTech Connect

    Donnelly, Patrick Joseph; McIver, Lauren; Gaines, Brian R.; Anderson, Erik; Collins, Michael Joseph; Thomas,Kurt Adam; McDaniel, Austin

    2007-09-01

    Remotely-fielded unattended sensor networks generally must operate at very low power--in the milliwatt or microwatt range--and thus have extremely limited communications bandwidth. Such sensors might be asleep most of the time to conserve power, waking only occasionally to transmit a few bits. RFID tags for tracking or material control have similarly tight bandwidth constraints, and emerging nanotechnology devices will be even more limited. Since transmitted data is subject to spoofing, and since sensors might be located in uncontrolled environments vulnerable to physical tampering, the high-consequence data generated by such systems must be protected by cryptographically sound authentication mechanisms; but such mechanisms are often lacking in current sensor networks. One reason for this undesirable situation is that standard authentication methods become impractical or impossible when bandwidth is severely constrained; if messages are small, a standard digital signature or HMAC will be many times larger than the message itself, yet it might be possible to spare only a few extra bits per message for security. Furthermore, the authentication tags themselves are only one part of cryptographic overhead, as key management functions (distributing, changing, and revoking keys) consume still more bandwidth. To address this problem, we have developed algorithms that provide secure authentication while adding very little communication overhead. Such techniques will make it possible to add strong cryptographic guarantees of data integrity to a much wider range of systems.

  13. Broad Bandwidth Telecommunications Systems.

    ERIC Educational Resources Information Center

    Sodolski, John

    Broad bandwidth transmission systems have been around for years. They include microwave, assorted cable systems, and recently, satellites. With the exception of some privately owned systems, broadband services have been furnished by the common carriers. Recently, a new element has been added--Cable Antenna Television (CATV) distribution systems.…

  14. Bandwidth in bolometric interferometry

    NASA Astrophysics Data System (ADS)

    Charlassier, R.; Bunn, E. F.; Hamilton, J.-Ch.; Kaplan, J.; Malu, S.

    2010-05-01

    Context. Bolometric interferometry is a promising new technology with potential applications to the detection of B-mode polarization fluctuations of the cosmic microwave background (CMB). A bolometric interferometer will have to take advantage of the wide spectral detection band of its bolometers to be competitive with imaging experiments. A crucial concern is that interferometers are assumed to be significantly affected by a spoiling effect known as bandwidth smearing. Aims: We investigate how the bandwidth modifies the work principle of a bolometric interferometer and affects its sensitivity to the CMB angular power spectra. Methods: We obtain analytical expressions for the broadband visibilities measured by broadband heterodyne and bolometric interferometers. We investigate how the visibilities must be reconstructed in a broadband bolometric interferometer and show that this critically depends on hardware properties of the modulation phase shifters. If the phase shifters produce shifts that are constant with respect to frequency, the instrument works like its monochromatic version (the modulation matrix is not modified), while if they vary (linearly or otherwise) with respect to frequency, one has to perform a special reconstruction scheme, which allows the visibilities to be reconstructed in frequency subbands. Using an angular power spectrum estimator that accounts for the bandwidth, we finally calculate the sensitivity of a broadband bolometric interferometer. A numerical simulation is performed that confirms the analytical results. Results: We conclude that (i) broadband bolometric interferometers allow broadband visibilities to be reconstructed regardless of the type of phase shifters used and (ii) for dedicated B-mode bolometric interferometers, the sensitivity loss caused by bandwidth smearing is quite acceptable, even for wideband instruments (a factor of 2 loss for a typical 20% bandwidth experiment).

  15. Meeting the Access Goal: Strategies for Increasing Access to Safe Drinking Water and Wastewater Treatment to American Indian and Alaska Native Villages - March 2008

    EPA Pesticide Factsheets

    This document describes the key barriers to improving access to safe drinking water and wastewater disposal in Indian country and offers recommendations on how to reduce these barriers to increase access.

  16. Optical Access Networks

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Ansari, Nirwan

    2005-01-01

    Call for Papers: Optical Access Networks

    Guest Editors Jun Zheng, University of Ottawa Nirwan Ansari, New Jersey Institute of Technology

    Submission Deadline: 1 June 2005

    Background

    With the wide deployment of fiber-optic technology over the past two decades, we have witnessed a tremendous growth of bandwidth capacity in the backbone networks of today's telecommunications infrastructure. However, access networks, which cover the "last-mile" areas and serve numerous residential and small business users, have not been scaled up commensurately. The local subscriber lines for telephone and cable television are still using twisted pairs and coaxial cables. Most residential connections to the Internet are still through dial-up modems operating at a low speed on twisted pairs. As the demand for access bandwidth increases with emerging high-bandwidth applications, such as distance learning, high-definition television (HDTV), and video on demand (VoD), the last-mile access networks have become a bandwidth bottleneck in today's telecommunications infrastructure. To ease this bottleneck, it is imperative to provide sufficient bandwidth capacity in the access networks to open the bottleneck and thus present more opportunities for the provisioning of multiservices. Optical access solutions promise huge bandwidth to service providers and low-cost high-bandwidth services to end users and are therefore widely considered the technology of choice for next-generation access networks. To realize the vision of optical access networks, however, many key issues still need to be addressed, such as network architectures, signaling protocols, and implementation standards. The major challenges lie in the fact that an optical solution must be not only robust, scalable, and flexible, but also implemented at a low cost comparable to that of existing access solutions in order to increase the

  17. Increasing Access to Higher Education through Open and Distance Learning: Empirical Findings from Mzuzu University, Malawi

    ERIC Educational Resources Information Center

    Chawinga, Winner Dominic; Zozie, Paxton Andrew

    2016-01-01

    Slowly but surely, open and distance learning (ODL) programmes are being regarded as one of the most practical ways that universities across the world are increasingly adopting in order to increase access to university education. Likewise, Mzuzu University (MZUNI) set up the Centre for Open and Distance Learning (CODL) to oversee the running of…

  18. Effective File I/O Bandwidth Benchmark

    SciTech Connect

    Rabenseifner, R.; Koniges, A.E.

    2000-02-15

    The effective I/O bandwidth benchmark (b{_}eff{_}io) covers two goals: (1) to achieve a characteristic average number for the I/O bandwidth achievable with parallel MPI-I/O applications, and (2) to get detailed information about several access patterns and buffer lengths. The benchmark examines ''first write'', ''rewrite'' and ''read'' access, strided (individual and shared pointers) and segmented collective patterns on one file per application and non-collective access to one file per process. The number of parallel accessing processes is also varied and well-formed I/O is compared with non-well formed. On systems, meeting the rule that the total memory can be written to disk in 10 minutes, the benchmark should not need more than 15 minutes for a first pass of all patterns. The benchmark is designed analogously to the effective bandwidth benchmark for message passing (b{_}eff) that characterizes the message passing capabilities of a system in a few minutes. First results of the b{_}eff{_}io benchmark are given for IBM SP and Cray T3E systems and compared with existing benchmarks based on parallel Posix-I/O.

  19. Increasing Access to Farmers Markets for Beneficiaries of Nutrition Assistance: Evaluation of the Farmers Market Access Project

    PubMed Central

    Cole, Kate; Kinney, Karen; Fisher, Kari; Krieger, James W.

    2013-01-01

    Introduction Increased acceptance of nutrition benefits at farmers markets could improve access to nutritious foods for low-income shoppers. The objective of this study was to evaluate a pilot project to increase participation by farmers markets and their vendors in the Supplemental Nutrition Assistance Program (SNAP) and Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). Methods The intervention targeted 9 markets in lower-income regions of King County, Washington. Markets and vendors were offered subsidized electronic benefits transfer (EBT) terminals for processing SNAP, and vendors could apply to accept WIC cash value vouchers. WIC staff received information on using SNAP and vouchers at farmers markets. We used mixed methods post-implementation to measure participation, describe factors in acceptance of benefits, and assess information needs for WIC staff to conduct effective outreach. Results Of approximately 88 WIC-eligible vendors, 38 agreed to accept vouchers. Ten of 125 vendors installed an EBT terminal, and 6 markets installed a central market terminal. The number of market stalls accepting SNAP increased from 80 to 143, an increase of 79%. Participating vendors wanted to provide access to SNAP and WIC shoppers, although redemption rates were low. Some WIC staff members were unfamiliar with markets, which hindered outreach. Conclusion Vendors and markets value low-income shoppers and, when offered support, will take on some inconvenience to serve them. To improve participation and sustainability, we recommend ongoing subsidies and streamlined procedures better suited to meet markets’ capabilities. Low EBT redemption rates at farmers markets suggest a need for more outreach to low-income shoppers and relationship building with WIC staff. PMID:24135392

  20. Managing high-bandwidth real-time data storage

    SciTech Connect

    Bigelow, David D.; Brandt, Scott A; Bent, John M; Chen, Hsing-Bung

    2009-09-23

    There exist certain systems which generate real-time data at high bandwidth, but do not necessarily require the long-term retention of that data in normal conditions. In some cases, the data may not actually be useful, and in others, there may be too much data to permanently retain in long-term storage whether it is useful or not. However, certain portions of the data may be identified as being vitally important from time to time, and must therefore be retained for further analysis or permanent storage without interrupting the ongoing collection of new data. We have developed a system, Mahanaxar, intended to address this problem. It provides quality of service guarantees for incoming real-time data streams and simultaneous access to already-recorded data on a best-effort basis utilizing any spare bandwidth. It has built in mechanisms for reliability and indexing, can scale upwards to meet increasing bandwidth requirements, and handles both small and large data elements equally well. We will show that a prototype version of this system provides better performance than a flat file (traditional filesystem) based version, particularly with regard to quality of service guarantees and hard real-time requirements.

  1. ABB: active bandwidth broker

    NASA Astrophysics Data System (ADS)

    Wong, Kason; Law, Eddie

    2001-07-01

    In this paper, we shall discuss a novel design on the policy-based management for the Internet. This design deploys the concept of active networking. As opposed to the traditional network design, active network empowers network node with the ability to manipulate data and program code in packets, and configure the network properties according to the needs of different applications. The policy-based management can control network routers in order to realize end-to-end Quality of Service (QoS), such as differentiated and integrated services, across the Internet. For the moment, the Internet Engineering Task Force (IETF) has defined the framework of the policy-based management. It employs a simple client/server model that uses Common Open Policy Service (COPS) protocol to facilitate policy management and control. Our design of Active Bandwidth Broker (ABB) belongs to an active application. Our goals are to distribute centralized workload of the policy-based management over multiple active nodes in the active networks, introduce mobility of the bandwidth brokers, and allows load sharing to the policy-based management. This results a network-wide intelligent, highly available, and consistent QoS control that allows performance protection for voice, video and Internet business application while reducing costs for growing networks.

  2. One State's Initiative to Increase Access to Higher Education for People with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Mock, Martha; Love, Kristen

    2012-01-01

    This article focuses on a state-based initiative to engage youth with intellectual disabilities (ID), their families, universities, schools, agencies, and funders in improving access to inclusive postsecondary education (PSE). As opportunities in higher education for students with ID continue to increase across United States, there are differing…

  3. Videophone Technology and Students with Deaf-Blindness: A Method for Increasing Access and Communication

    ERIC Educational Resources Information Center

    Emerson, Judith; Bishop, John

    2012-01-01

    Introduction: Seeing the Possibilities with Videophone Technology began as research project funded by the National Center for Technology Innovation. The project implemented a face-to-face social networking program for students with deaf-blindness to investigate the potential for increasing access and communication using videophone technology.…

  4. Smile Alabama! Initiative: Interim Results from a Program To Increase Children's Access to Dental Care.

    ERIC Educational Resources Information Center

    Greene-McIntyre, Mary; Finch, Mary Hayes; Searcy, John

    2003-01-01

    An Alabama initiative aimed to improve access to oral health care for Medicaid-eligible children through four components: improved Medicaid claims processing, increased reimbursement for providers, outreach and educational activities to support providers, and parent and patient education about children's oral health. In the first 3 program years,…

  5. Increasing Accessibility: Using Universal Design Principles to Address Disability Impairments in the Online Learning Environment

    ERIC Educational Resources Information Center

    Pittman, Candice N.; Heiselt, April K.

    2014-01-01

    With the increasing number of students enrolling in distance education, there is a need to consider the accessibility of course materials in online learning environments. Four major groups of disabilities: mobility, auditory, visual, and cognitive are explored as they relate to their implementation into instructional design and their impact on…

  6. Increasing Access for Low-Income Students and Making Financial Education a Priority for Higher Education

    ERIC Educational Resources Information Center

    Kezar, Adrianna

    2009-01-01

    While widespread financial illiteracy and reduced opportunities for low-income students to participate in higher education may seem unrelated, both challenges can be addressed through Individual Development Accounts (IDAs), an existing but widely underutilized tool. IDAs have the potential both to increase access and retention of low-income…

  7. Adding it Up: State Challenges for Increasing College Access and Success

    ERIC Educational Resources Information Center

    Jobs for the Future, 2007

    2007-01-01

    This report, comprised of key indicators and projections related to postsecondary attainment, is designed to help institutional, system, and state leaders advance a conversation about the need to increase college access and success for all students. The profiles included show that while states vary considerably in their current and expected…

  8. International Development and Research Capacities: Increasing Access to African Scholarly Publishing

    ERIC Educational Resources Information Center

    Metcalfe, Amy Scott; Esseh, Samuel; Willinsky, John

    2009-01-01

    This paper examines the evolving relationship between Canada and the African academic research community through the promotion of a concept known as Information and Communication Technology for Development (ICT4D) and with an eye to its implications for increasing the circulation of research through such means as open access (OA) publishing…

  9. Is Increased Access Enough? Advanced Placement Courses, Quality, and Success in Low-Income Urban Schools

    ERIC Educational Resources Information Center

    Hallett, Ronald E.; Venegas, Kristan M.

    2011-01-01

    This article combines descriptive statistics and interviews with college-bound high school students to explore the connection between increased access and academic quality of Advanced Placement (AP) courses in low-income urban high schools. Results suggest that although moderately more opportunities to take AP courses exist than in previous years,…

  10. Telehealth: Increasing Access to High Quality Care by Expanding the Role of Technology in Correctional Medicine

    PubMed Central

    Young, Jeremy D.; Badowski, Melissa E.

    2017-01-01

    The United States (US) has a large correctional population. However, many incarcerated persons lack access to evidence-based, up-to-date medical care, particularly by subspecialty providers, due to limitations of geography, travel, cost and other resources. The use of telehealth technologies can remove these barriers, increasing access to high quality, multidisciplinary care. Studies have shown that, with telemedicine, timely triage and medical management can be provided across many disciplines, which may lead to improved clinical outcomes and significant cost savings. PMID:28208807

  11. Building a foundation for systems change: increasing access to physical activity programs for older adults.

    PubMed

    Lachenmayr, Sue; Mackenzie, Geraldine

    2004-10-01

    Although 25% of U.S. adults are physically inactive, this percentage increases dramatically for older adults. Organizational change theory guided a state health department in identifying system gaps and developing strategies to expand programming for seniors. A survey of provider agencies in New Jersey assessed (a) capacity for physical activity programs for older adults, (b) accessibility of programs, and (c) barriers to providing programs. One hundred sixty agencies provided physical activity programs to almost 184,000 individuals annually. Fewer than one half of the agencies provided exercise programs for people with disabilities, and only 44% provided in-home programs. Eighty-two percent of program providers wanted to expand programming but cited lack of trained instructors and peer leaders, inadequate facility space, insufficient funding, and limited transportation resources as barriers. Sustaining older adult behavior change requires infrastructure that will ensure access to diverse physical activities. This article provides strategies to expand access to physical activity programs for older adults.

  12. Ensuring Access to Safe, Legal Abortion in an Increasingly Complex Regulatory Environment.

    PubMed

    Paul, Maureen; Norton, Mary E

    2016-07-01

    Restrictions on access to abortion in the United States have reached proportions unprecedented since the nationwide legalization of abortion in 1973. Although some restrictions aim to discourage women from having abortions, many others impede access by affecting the timeliness, affordability, or availability of services. Evidence indicates that these restrictions do not increase abortion safety; rather, they create logistic barriers for women seeking abortion, and they have the greatest effect on women with the fewest resources. In this commentary, we recall the important role that obstetrician-gynecologists (ob-gyns) have played, both before and after Roe v. Wade, in facilitating access to safe abortion care. Using the literature on abortion safety and access as a foundation, we propose several practical ideas about what we as ob-gyns can do to address the current threat to abortion access, whether or not we provide abortion services in practice. We hope that this commentary will encourage discourse within our profession and prompt other suggestions. As ob-gyns who are dedicated to addressing health disparities and promoting the health and well-being of our patients, we can make a difference.

  13. Increasing access to healthful foods: a qualitative study with residents of low-income communities

    PubMed Central

    2015-01-01

    Background Inadequate access to healthful foods has been identified as a significant barrier to healthful dietary behaviors among individuals who live in low-income communities. The purpose of this study was to gather low-income community members’ opinions about their food purchasing choices and their perceptions of the most effective ways to increase access to healthful foods in their communities. Methods Spanish and English focus groups were conducted in low-income, ethnically-diverse communities. Participants were asked about their knowledge, factors influencing their food purchasing decisions, and their perceptions regarding solutions to increase access to healthful foods. Results A total of 148 people participated in 13 focus groups. The majority of participants were female and ethnically diverse (63% Hispanic, 17% African American, 16% Caucasian, and 4% “other”). More than 75% of the participants reported making less than $1999 USD per month. Participants reported high levels of knowledge and preference for healthful foods. The most important barriers influencing healthful shopping behaviors included high price of healthful food, inadequate geographical access to healthful food, poor quality of available healthful food, and lack of overall quality of the proximate retail stores. Suggested solutions to inadequate access included placement of new chain supermarkets in their communities. Strategies implemented in convenience stores were not seen as effective. Farmers’ markets, with specific stipulations, and community gardens were regarded as beneficial supplementary solutions. Conclusion The results from the focus groups provide important input from a needs assessment perspective from the community, identify gaps in access, and offer potential effective solutions to provide direction for the future. PMID:26222910

  14. Memory bandwidth-scalable motion estimation for mobile video coding

    NASA Astrophysics Data System (ADS)

    Hsieh, Jui-Hung; Tai, Wei-Cheng; Chang, Tian-Sheuan

    2011-12-01

    The heavy memory access of motion estimation (ME) execution consumes significant power and could limit ME execution when the available memory bandwidth (BW) is reduced because of access congestion or changes in the dynamics of the power environment of modern mobile devices. In order to adapt to the changing BW while maintaining the rate-distortion (R-D) performance, this article proposes a novel data BW-scalable algorithm for ME with mobile multimedia chips. The available BW is modeled in a R-D sense and allocated to fit the dynamic contents. The simulation result shows 70% BW savings while keeping equivalent R-D performance compared with H.264 reference software for low-motion CIF-sized video. For high-motion sequences, the result shows our algorithm can better use the available BW to save an average bit rate of up to 13% with up to 0.1-dB PSNR increase for similar BW usage.

  15. Does Improved Water Access Increase Child School Attendance? A Quasi-Experimental Approach From Rural Ethiopia

    NASA Astrophysics Data System (ADS)

    Masuda, Y.; Cook, J.

    2012-12-01

    This paper analyzes the impact of improved water access on child school attendance using two years of primary panel data from a quasi-experimental study in Oromiya, Ethiopia. A predominant form of child labor in rural poor households in least developed countries is water collection. Girls are often the primary water collectors for households, and because of the time intensive nature of water collection improved water access may allow for time to be reallocated to schooling (Rosen and Vincent 1999; Nankhuni and Findeis 2004). Understanding how improved water access may increase schooling for girls has important development policy implications. Indeed, abundant research on returns to education suggests increased schooling for girls is tied to improved future child and maternal health, economic opportunities, and lower fertility rates (Handa 1996; Schultz 1998; Michaelowa 2000). The literature to date finds that improved water access leads to increased schooling; however, there still exists a clear gap in the literature for understanding this relationship for two reasons. First, only four studies have directly examined the relationship between improved water access and schooling in sub-Saharan Africa, and analyses have been limited due to the use of cross-sectional data and research designs (Nankhuni and Findeis 2004; Koolwal and Van de Walle 2010; Ndiritu and Nyangan 2011; Nauges and Strand 2011). Indeed, only two studies have attempted to control for the endogenous nature of water access. Second, all studies use a binary school enrollment indicator from household surveys, which may suffer from response bias and may be an imperfect measure for actual schooling. Respondents may feel pressured to report that their children are enrolled in school if, like in Ethiopia, there are compulsory education laws. This may result in an overestimation of school enrollment. In addition, most children from rural poor households combine work and school, and a binary indicator does

  16. Increasing Access to Cost Effective Home-Based Rehabilitation for Rural Veteran Stroke Survivors

    PubMed Central

    Housley, SN; Garlow, AR; Ducote, K; Howard, A; Thomas, T; Wu, D; Richards, K; Butler, AJ

    2016-01-01

    Introduction An estimated 750,000 Americans experience a stroke annually. Most stroke survivors require rehabilitation. Limited access to rehabilitation facilities has a pronounced burden on functional outcomes and quality of life. Robotic devices deliver reproducible therapy without the need for real-time human oversight. This study examined the efficacy of using home-based, telerobotic-assisted devices (Hand and Foot Mentor: HM and FM) to improve functional ability and reduce depression symptoms, while improving access and cost savings associated with rehabilitation. Methods Twenty stroke survivors performed three months of home-based rehabilitation using a robotic device, while a therapist remotely monitored progress. Baseline and end of treatment function and depression symptoms were assessed. Satisfaction with the device and access to therapy were determined using qualitative surveys. Cost analysis was performed to compare home-based, robotic-assisted therapy to clinic-based physical therapy. Results Compared to baseline, significant improvement in upper extremity function (30.06%, p= 0.046), clinically significant benefits in gait speed (29.03%), moderate improvement in depressive symptoms (28.44%) and modest improvement in distance walked (30.2%) were observed. Participants indicated satisfaction with the device. Home-based robot therapy expanded access to post-stroke rehabilitation for 35% of the people no longer receiving formal services and increased daily access for the remaining 65%, with a cost savings of $2,352 (64.97%) compared to clinic-based therapy. Conclusion Stroke survivors made significant clinically meaningful improvements in the use of their impaired extremities using a robotic device in the home. Home-based, robotic therapy reduced costs, while expanding access to a rehabilitation modality for people who would not otherwise have received care. PMID:28018979

  17. Increasing access to fruits and vegetables: perspectives from the New York City experience.

    PubMed

    Sacks, Rachel; Yi, Stella S; Nonas, Cathy

    2015-05-01

    Broad recognition now exists that price, availability, and other structural factors are meaningful barriers to fruit and vegetable consumption, particularly among low-income adults. Beginning in 2005, the New York City Department of Health and Mental Hygiene used the social-ecological model to develop a multifaceted effort to increase fruit and vegetable access citywide, with emphasis in low-income neighborhoods. Overall, the percentage of New York City adults who reported consuming no fruits and vegetables in the previous day decreased slightly over a 10-year period (2002: 14.3% [95% confidence interval = 13.4%, 15.2%]; 2012: 12.5% [95% confidence interval = 11.4%, 13.6%]; P for trend < .001). Our approach hypothesizes that complementary initiatives, implemented simultaneously, will create a citywide food environment that fuels changes in social norms and cultural preferences, increases consumer demand, and supports sustainable access to affordable produce.

  18. Increasing Discoverability and Accessibility of NASA Atmospheric Science Data Center (ASDC) Data Products with GIS Technology

    NASA Astrophysics Data System (ADS)

    Ross, A.; Tisdale, B.; Tisdale, M.; Northup, E. A.; Kusterer, J.

    2014-12-01

    NASA's Atmospheric Science Data Center (ASDC) is utilizing Geographic Information System (GIS) technology that can increase data discoverability and accessibility of ASDC data to the GIS user community. Data products have had compatibility issues, limiting their use in open source as well as commercial tools, such as Esri's ArcGIS Platform. The ASDC is working in collaboration with ESDIS, Esri, The HDF Group, and George Mason University (GMU) to identify and address these compatibility issues. Once addressed, web services can be created on top of the data sets and accessed through desktop, mobile, and web based GIS tools. These services include the Open Geospatial Consortium (OGC) Web Mapping Service, OGC Web Coverage Service, and Image Service. Exposing services through desktop, mobile, and web based GIS tools is expected to yield a greater usage of NASA ASDC data as well as new analysis utilizing GIS tools for an increased understanding in the areas of the earth's radiation budget, clouds, aerosols, and tropospheric chemistry.

  19. Optimal resource allocation in random networks with transportation bandwidths

    NASA Astrophysics Data System (ADS)

    Yeung, C. H.; Wong, K. Y. Michael

    2009-03-01

    We apply statistical physics to study the task of resource allocation in random sparse networks with limited bandwidths for the transportation of resources along the links. Recursive relations from the Bethe approximation are converted into useful algorithms. Bottlenecks emerge when the bandwidths are small, causing an increase in the fraction of idle links. For a given total bandwidth per node, the efficiency of allocation increases with the network connectivity. In the high connectivity limit, we find a phase transition at a critical bandwidth, above which clusters of balanced nodes appear, characterized by a profile of homogenized resource allocation similar to the Maxwell construction.

  20. Cutter Connectivity Bandwidth Study

    NASA Astrophysics Data System (ADS)

    2002-10-01

    The goal of this study was to determine how much bandwidth is required for cutters to meet emerging data transfer requirements. The Cutter Connectivity Business Solutions Team with guidance front the Commandant's 5 Innovation Council sponsored this study. Today, many Coast Guard administrative and business functions are being conducted via electronic means. Although our larger cutters can establish part-time connectivity using commercial satellite communications (SATCOM) while underway, there are numerous complaints regarding poor application performance. Additionally, smaller cutters do not have any standard means of underway connectivity. The R&D study shows the most important factor affecting web performance and enterprise applications onboard cutters was latency. Latency describes the time it takes the signal to reach the satellite and come back down through space. The latency due to use of higher orbit satellites is causing poor application performance and inefficient use of expensive SATCOM links. To improve performance, the CC must, (1) reduce latency by using alternate communications links such as low-earth orbit satellites, (2) tailor applications to the SATCOM link and/or (3) optimize protocols used for data communication to minimize time required by present applications to establish communications between the user and the host systems.

  1. Accessibility

    EPA Pesticide Factsheets

    Federal laws, including Section 508 of the Rehabilitation Act, mandate that people with disabilities have access to the same information that someone without a disability would have. 508 standards cover electronic and information technology (EIT) products.

  2. Increasing access to prenatal care: disease prevention and sound business practice.

    PubMed

    Wilson-Mitchell, Karline

    2014-02-01

    Following our study of birth outcomes for uninsured new immigrant and refugee women in Toronto, we discovered clinically significant numbers of women with hypertension and diabetes. As this population ages and prevalence increases, the expense of treating uncontrolled chronic illness increases. Prudent health policy change, a reduction in treatment delays, and equitable access to care will decrease clinical risk and limit the financial burden on the health care system. This unanticipated finding supports the argument for establishing government-funded maternity care insurance for all women. Such policies could prevent perinatal complications and decrease the rate of uncontrolled chronic illness later in life.

  3. Improved-Bandwidth Transimpedance Amplifier

    NASA Technical Reports Server (NTRS)

    Chapsky, Jacob

    2009-01-01

    The widest available operational amplifier, with the best voltage and current noise characteristics, is considered for transimpedance amplifier (TIA) applications where wide bandwidth is required to handle fast rising input signals (as for time-of-flight measurement cases). The added amplifier inside the TIA feedback loop can be configured to have slightly lower voltage gain than the bandwidth reduction factor.

  4. Estimating Bottleneck Bandwidth using TCP

    NASA Technical Reports Server (NTRS)

    Allman, Mark

    1998-01-01

    Various issues associated with estimating bottleneck bandwidth using TCP are presented in viewgraph form. Specific topics include: 1) Why TCP is wanted to estimate the bottleneck bandwidth; 2) Setting ssthresh to an appropriate value to reduce loss; 3) Possible packet-pair solutions; and 4) Preliminary results: ACTS and the Internet.

  5. Increasing Access to Treatment for Chagas Disease: The Case of Morelos, Mexico

    PubMed Central

    Manne-Goehler, Jennifer; Ramsey, Janine M.; Salgado, Marco Ocampo; Wirtz, Veronika J.; Reich, Michael R.

    2014-01-01

    Chagas disease is a neglected vector-borne disease with an estimated prevalence of 1.1 million cases in Mexico. Recent research showed that access to treatment of Chagas disease is limited in Mexico, with < 0.5% of infected cases treated. This brief report used quantitative data from the Morelos Program on Chagas disease and qualitative analysis of key informant interviews to examine strategies to increase treatment access for infected patients in Morelos, Mexico. From 2007 to 2011, 263 (9.2%) of the registered cases of Chagas disease in Mexico occurred in Morelos. Among these, 152 (57.8%) were treated and 97.3% of those treated received benznidazole. The assessment finds that state officials decided to directly purchase benznidazole from the distributor to increase access and improve clinical quality of treatment of patients in their state. They also faced significant barriers, especially in regulation and health system organization, which limited efforts to make high quality treatment available. PMID:25266353

  6. Out of sight, out of mind: racial retrieval cues increase the accessibility of social justice concepts.

    PubMed

    Salter, Phia S; Kelley, Nicholas J; Molina, Ludwin E; Thai, Luyen T

    2017-01-16

    Photographs provide critical retrieval cues for personal remembering, but few studies have considered this phenomenon at the collective level. In this research, we examined the psychological consequences of visual attention to the presence (or absence) of racially charged retrieval cues within American racial segregation photographs. We hypothesised that attention to racial retrieval cues embedded in historical photographs would increase social justice concept accessibility. In Study 1, we recorded gaze patterns with an eye-tracker among participants viewing images that contained racial retrieval cues or were digitally manipulated to remove them. In Study 2, we manipulated participants' gaze behaviour by either directing visual attention toward racial retrieval cues, away from racial retrieval cues, or directing attention within photographs where racial retrieval cues were missing. Across Studies 1 and 2, visual attention to racial retrieval cues in photographs documenting historical segregation predicted social justice concept accessibility.

  7. Increasing Access and Usability of Remote Sensing Data: The NASA Protected Area Archive

    NASA Technical Reports Server (NTRS)

    Geller, Gary N.

    2004-01-01

    Although remote sensing data are now widely available, much of it at low or no-cost, many managers of protected conservation areas do not have the expertise or tools to view or analyze it. Thus access to it by the protected area management community is effectively blocked. The Protected Area Archive will increase access to remote sensing data by creating collections of satellite images of protected areas and packaging them with simple-to-use visualization and analytical tools. The user can easily locate the area and image of interest on a map, then display, roam, and zoom the image. A set of simple tools will be provided so the user can explore the data and employ it to assist in management and monitoring of their area. The 'Phase 1 ' version requires only a Windows-based computer and basic computer skills, and may be of particular help to protected area managers in developing countries.

  8. Fast Faraday Cup With High Bandwidth

    DOEpatents

    Deibele, Craig E [Knoxville, TN

    2006-03-14

    A circuit card stripline Fast Faraday cup quantitatively measures the picosecond time structure of a charged particle beam. The stripline configuration maintains signal integrity, and stitching of the stripline increases the bandwidth. A calibration procedure ensures the measurement of the absolute charge and time structure of the charged particle beam.

  9. Frequency Bandwidth Optimization of Left-Handed Metamaterial

    NASA Technical Reports Server (NTRS)

    Chevalier, Christine T.; Wilson, Jeffrey D.

    2004-01-01

    Recently, left-handed metamaterials (LHM s) have been demonstrated with an effective negative index of refraction and with antiparallel group and phase velocities for microwave radiation over a narrow frequency bandwidth. In order to take advantage of these characteristics for practical applications, it will be beneficial to develop LHM s with increased frequency bandwidth response and lower losses. In this paper a commercial three-dimensional electromagnetic simulation code is used to explore the effects of geometry parameter variations on the frequency bandwidth of a LHM at microwave frequencies. Utilizing an optimizing routine in the code, a geometry was generated with a bandwidth more than twice as large as the original geometry.

  10. NASA Plan for Increasing Access to the Results of Scientific Research

    NASA Technical Reports Server (NTRS)

    2014-01-01

    This plan is issued in response to the Executive Office of the President's February 22, 2013, Office of Science and Technology Policy (OSTP) Memorandum for the Heads of Executive Departments and Agencies, "Increasing Access to the Results of Federally Funded Scientific Research." Through this memorandum, OSTP directed all agencies with more than $100 million in annual research and development expenditures to prepare a plan for improving the public's access to the results of federally funded research. The National Aeronautics and Space Administration (NASA) invests on the order of $3 billion annually in fundamental and applied research and technology development1 across a broad range of topics, including space and Earth sciences, life and physical sciences, human health, aeronautics, and technology. Promoting the full and open sharing of data with research communities, private industry, academia, and the general public is one of NASA's longstanding core values. For example, NASA's space and suborbital mission personnel routinely process, archive, and distribute their data to researchers around the globe. This plan expands the breadth of NASA's open-access culture to include data and publications for all of the scientific research that the Agency sponsors.

  11. Increasing access to terrestrial ecology and remote sensing (MODIS) data through Web services and visualization tools

    NASA Astrophysics Data System (ADS)

    Santhana Vannan, S.; Cook, R. B.; Wei, Y.

    2012-12-01

    In recent years user access to data and information is increasingly handled through tools, services, and applications. Standards-based services have facilitated this development. These service-based methods to access data has boosted the use of data and in increasingly complex ways. The Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) has taken the approach of service-based access to data and visualization for distribution and visualization of its terrestrial ecology data, including MODIS (Moderate Resolution Imaging Spectroradiometer) remote sensing data products. The MODIS data products are highly useful for field research. The spectral, spatial and temporal characteristics of MODIS products have made them an important data source for analyzing key science questions relating to Earth system processes at multiple spatial and temporal scales. However, MODIS data volume and the complexity in data format make it less usable in some cases. To solve this usability issue, the ORNL DAAC has developed a system that prepares and distributes subsets of selected MODIS land products in a scale and format useful for field researchers. Web and Web service tools provide MODIS subsets in comma-delimited text format and in GIS compatible GeoTIFF format. Users can download and visualize MODIS subsets for a set of pre-defined locations, order MODIS subsets for any land location or automate the process of subset extraction using a SOAP-based Web service. The MODIS tools and services can be extended to support the large volume of data that would be produced by the various decadal survey missions. http://daac.ornl.gov/MODIS . The ORNL DAAC has also created a Web-based Spatial Data Access Tool (SDAT) that enables users to browse, visualize, and download a wide variety of geospatial data in various user-selected spatial/temporal extents, formats, and projections. SDAT is based on Open Geospatial Consortium (OGC) Web service standards that allows users to

  12. Committee Opinion No. 642: Increasing Access to Contraceptive Implants and Intrauterine Devices to Reduce Unintended Pregnancy.

    PubMed

    2015-10-01

    Unintended pregnancy persists as a major public health problem in the United States. Although lowering unintended pregnancy rates requires multiple approaches, individual obstetrician-gynecologists may contribute by increasing access to contraceptive implants and intrauterine devices. Obstetrician-gynecologists should encourage consideration of implants and intrauterine devices for all appropriate candidates, including nulliparous women and adolescents. Obstetrician-gynecologists should adopt best practices for long-acting reversible contraception insertion. Obstetrician-gynecologists are encouraged to advocate for coverage and appropriate payment and reimbursement for every contraceptive method by all payers in all clinically appropriate circumstances.

  13. Using Mobile Fruit Vendors to Increase Access to Fresh Fruit and Vegetables for Schoolchildren

    PubMed Central

    Yen, Irene H.; Laraia, Barbara

    2012-01-01

    This study explored the extent to which schoolchildren purchased precut and bagged fruits and vegetables from a mobile fruit vendor (frutero). During 14 days in fall 2008, a frutero sold fruits and vegetables at the entrance of an elementary school; 59% of the frutero’s 233 consumers of 248 items were elementary-school students. With each successive day, an average of 1 additional bag of fruits and vegetables was sold by the frutero and 1.5 fewer nonnutritious foods by a competing vendor. Policies encouraging the sale of nutritious foods from mobile food vendors may increase access for schoolchildren. PMID:22632739

  14. Can innovative health financing policies increase access to MDG-related services? Evidence from Rwanda.

    PubMed

    Sekabaraga, Claude; Diop, Francois; Soucat, Agnes

    2011-11-01

    Ensuring financial access to health services is a critical challenge for poor countries if they are to reach the health Millennium Development Goals (MDGs). This article examines the case of Rwanda, a country which has championed innovative health care financing policies. Between 2000 and 2007, Rwanda has improved financial access for the poor, increased utilization of health services and reduced out-of-pocket payments for health care. Poor groups' utilization has increased for all health services, sometimes dramatically. Use of assisted deliveries, for example, increased from 12.1% to 42.7% among the poorest quintile; payments at the point of delivery have also been reduced; and catastrophic expenditures have declined. Part of these achievements is likely linked to innovative health financing policies, particularly the expansion of micro-insurance ('mutuelles') and performance-based financing. The paper concludes that the Rwanda experience provides a useful example of effective implementation of policies that reduce the financial barrier to health services, hereby contributing to the health MDGs. Today's main challenge is to build the sustainability of this system. Finally, the paper proposes a simple set of rigorous metrics to assess the impact of health financing policies and calls for implementing rigorous impact evaluation of health care financing policies in low-income countries.

  15. Evaluation of Cognitively Accessible Software to Increase Independent Access to Cellphone Technology for People with Intellectual Disability

    ERIC Educational Resources Information Center

    Stock, S. E.; Davies, D. K.; Wehmeyer, M. L.; Palmer, S. B.

    2008-01-01

    Background: There are over two billion telephones in use worldwide. Yet, for millions of Americans with intellectual disabilities (ID), access to the benefits of cellphone technology is limited because of deficits in literacy, numerical comprehension, the proliferation of features and shrinking size of cellphone hardware and user interfaces.…

  16. Web Accessibility in Europe and the United States: What We Are Doing to Increase Inclusion

    ERIC Educational Resources Information Center

    Wheaton, Joseph; Bertini, Patrizia

    2007-01-01

    Accessibility is hardly a new problem and certainly did not originate with the Web. Lack of access to buildings long preceded the call for accessible Web content. Although it is unlikely that rehabilitation educators look at Web page accessibility with indifference, many may also find it difficult to implement. The authors posit three reasons why…

  17. Increasing the Impact of High-Resolution Lidar Topography Through Online Data Access and Processing

    NASA Astrophysics Data System (ADS)

    Crosby, C. J.; Nandigam, V.; Baru, C.; Arrowsmith, R.

    2013-12-01

    ) project, collaborative research funded by the NASA ACCESS program, that makes NASA airborne and space based laser altimetry data (GLAS and LVIS) available through OT using federated web services. With several thousand active users, OT is an excellent example of a cyberinfrastructure-based airborne science data system that is enabling access to challenging data for research, education and outreach. OT has demonstrated that by democratizing access to lidar topography, the impact of these expensive research datasets is greatly increased, through reused in research, education, and commercial applications beyond their original scope. This presentation will highlight the OT system and lessons learned during its development. We will also highlight ongoing work related to creation of a more flexible and scalable high-performance environment for processing of large datasets; creation of a 'pluggable' infrastructure for third-party programs and algorithms to be run against the OT data holdings; and interoperability of OT with other earth science data systems.

  18. Does Household Gun Access Increase the Risk of Attempted Suicide?: Evidence from a National Sample of Adolescents

    ERIC Educational Resources Information Center

    Watkins, Adam M.; Lizotte, Alan J.

    2013-01-01

    The aim of this research is to assess if home firearm access increases the risk of nonfatal suicidal attempts among adolescents. Such a gun focus has largely been limited to case-control studies on completed suicides. This line of research has found that household gun access increases the risk of suicide due to features of available firearms…

  19. Extended heroin access increases heroin choices over a potent nondrug alternative.

    PubMed

    Lenoir, Magalie; Cantin, Lauriane; Vanhille, Nathalie; Serre, Fuschia; Ahmed, Serge H

    2013-06-01

    Epidemiological research shows that the proportion of drug users who become addicted to heroin is higher than to cocaine. Here we tested whether this difference could be due to a difference in the addiction liability between the two drugs. Addiction liability was assessed under a discrete-trials choice procedure by measuring the proportion of rats that prefer the drug over a potent alternative reward (ie, water sweetened with saccharin). Previous research on choice between self-administration of i.v. cocaine or sweet water showed that the proportion of cocaine-preferring rats remains relatively low and invariable (ie, 15%), even after extended drug access and regardless of past drug consumption (ie, total drug use before choice testing). By contrast, the present study shows that under similar choice conditions, the proportion of heroin-preferring rats considerably increases with extended heroin access (6-9 h per day for several weeks) and with past heroin consumption, from 11 to 51% at the highest past drug consumption level. At this level, the proportion of drug-preferring rats was about three times higher with heroin than with cocaine (51% vs 15%). This increase in the rate of heroin preference after extended heroin access persisted even after recovery from acute heroin withdrawal. Overall, these findings show that choice procedures are uniquely sensitive to different drugs and suggest that heroin is more addictive than cocaine. This higher addiction liability may contribute to explain why more drug users become addicted to heroin than to cocaine in epidemiological studies.

  20. Cost-effectiveness of Increasing Access to Contraception during the Zika Virus Outbreak, Puerto Rico, 2016

    PubMed Central

    Simmons, Katharine B.; Bertolli, Jeanne; Rivera-Garcia, Brenda; Cox, Shanna; Romero, Lisa; Koonin, Lisa M.; Valencia-Prado, Miguel; Bracero, Nabal; Jamieson, Denise J.; Barfield, Wanda; Moore, Cynthia A.; Mai, Cara T.; Korhonen, Lauren C.; Frey, Meghan T.; Perez-Padilla, Janice; Torres-Muñoz, Ricardo; Grosse, Scott D.

    2017-01-01

    We modeled the potential cost-effectiveness of increasing access to contraception in Puerto Rico during a Zika virus outbreak. The intervention is projected to cost an additional $33.5 million in family planning services and is likely to be cost-saving for the healthcare system overall. It could reduce Zika virus–related costs by $65.2 million ($2.8 million from less Zika virus testing and monitoring and $62.3 million from avoided costs of Zika virus–associated microcephaly [ZAM]). The estimates are influenced by the contraception methods used, the frequency of ZAM, and the lifetime incremental cost of ZAM. Accounting for unwanted pregnancies that are prevented, irrespective of Zika virus infection, an additional $40.4 million in medical costs would be avoided through the intervention. Increasing contraceptive access for women who want to delay or avoid pregnancy in Puerto Rico during a Zika virus outbreak can substantially reduce the number of cases of ZAM and healthcare costs. PMID:27805547

  1. Cost-effectiveness of Increasing Access to Contraception during the Zika Virus Outbreak, Puerto Rico, 2016.

    PubMed

    Li, Rui; Simmons, Katharine B; Bertolli, Jeanne; Rivera-Garcia, Brenda; Cox, Shanna; Romero, Lisa; Koonin, Lisa M; Valencia-Prado, Miguel; Bracero, Nabal; Jamieson, Denise J; Barfield, Wanda; Moore, Cynthia A; Mai, Cara T; Korhonen, Lauren C; Frey, Meghan T; Perez-Padilla, Janice; Torres-Muñoz, Ricardo; Grosse, Scott D

    2017-01-01

    We modeled the potential cost-effectiveness of increasing access to contraception in Puerto Rico during a Zika virus outbreak. The intervention is projected to cost an additional $33.5 million in family planning services and is likely to be cost-saving for the healthcare system overall. It could reduce Zika virus-related costs by $65.2 million ($2.8 million from less Zika virus testing and monitoring and $62.3 million from avoided costs of Zika virus-associated microcephaly [ZAM]). The estimates are influenced by the contraception methods used, the frequency of ZAM, and the lifetime incremental cost of ZAM. Accounting for unwanted pregnancies that are prevented, irrespective of Zika virus infection, an additional $40.4 million in medical costs would be avoided through the intervention. Increasing contraceptive access for women who want to delay or avoid pregnancy in Puerto Rico during a Zika virus outbreak can substantially reduce the number of cases of ZAM and healthcare costs.

  2. Multibeam Bathymetry Data Value and Increased Efficiency Through Improved Data Access and Reuse

    NASA Astrophysics Data System (ADS)

    Price, D. J.; Fischman, D.; Varner, J. D.; McLean, S. J.; Henderson, J. F.

    2012-12-01

    The costs associated with geophysical data collection are ever increasing, and efficiencies created by data reuse have never been more important. Multibeam sonar bathymetry, collected by specialized research vessels in challenging oceanic environments, is an example data type that has experienced steady increases in acquisition costs. The National Oceanic and Atmospheric Administration's (NOAA) National Geophysical Data Center (NGDC) in partnership with the Academic Fleet Rolling deck To Repository (R2R) program provides streamlined delivery of multibeam bathymetric data from ship to shore to user. By ensuring long term archive and easy access to these data, we foster the innovative reuse of data to produce additional products to serve multiple needs beyond the original intent of collection. Archived data are made widely accessible to the scientific community and the public via Web technologies that also support a "whole ocean" approach to management and planning, leveraging limited resources, and maximizing the benefit of the original investment in data collection. Currently, the public has access to more than 461,000 multibeam bathymetry files from the NGDC website through various Web based tools (ngdc.noaa.gov/mgg/bathymetry/). Data are discoverable through geospatial maps and text search options. Once data are identified, users can download individual files, bundled data, or create custom grids. This paper takes a closer look at the multibeam data downloaded from the NGDC website and attempts to quantify the value of providing data for reuse. Using the number of surveys downloaded, an average cost to collect and steward multibeam data, and computing the ship hours required to acquire these data, we can estimate the value of the data freely available through R2R and NGDC. We will show that the value of long term stewardship, sharing, and reuse of these data provides a significant return on the initial investment. Proper data stewardship by NOAA's National Data

  3. Increasing Access to an ASD Imitation Intervention Via a Telehealth Parent Training Program.

    PubMed

    Wainer, Allison L; Ingersoll, Brooke R

    2015-12-01

    Systematic research focused on developing and improving strategies for the dissemination and implementation of effective ASD services is essential. An innovative and promising area of research is the use of telehealth programs to train parents of children with ASD in intervention techniques. A hybrid telehealth program, combining self-directed internet-based instruction with remote coaching, was created to introduce parents of children with ASD to an imitation intervention. A single-subject multiple-baseline design study evaluated the effect of the program on changes in parent and child behavior. Parents improved in their use of the intervention techniques and their children demonstrated concurrent increases in spontaneous imitation skills. Parents also indicated that the intervention and telehealth service delivery model were acceptable, useable, and effective. Results suggest that this hybrid telehealth program has the potential to increase access to ASD services.

  4. Health and Federal Budgetary Effects of Increasing Access to Antiretroviral Medications for HIV by Expanding Medicaid

    PubMed Central

    Kahn, James G.; Haile, Brain; Kates, Jennifer; Chang, Sophia

    2001-01-01

    Objectives. This study modeled the health and federal fiscal effects of expanding Medicaid for HIV-infected people to improve access to highly active antiretroviral therapy. Methods. A disease state model of the US HIV epidemic, with and without Medicaid expansion, was used. Eligibility required a CD4 cell count less than 500/mm3 or viral load greater than 10 000, absent or inadequate medication insurance, and annual income less than $10 000. Two benefits were modeled, “full” and “limited” (medications, outpatient care). Federal spending for Medicaid, Medicare, AIDS Drug Assistance Program, Supplemental Security Income, and Social Security Disability Insurance were assessed. Results. An estimated 38 000 individuals would enroll in a Medicaid HIV expansion. Over 5 years, expansion would prevent an estimated 13 000 AIDS diagnoses and 2600 deaths and add 5816 years of life. Net federal costs for all programs are $739 million (full benefits) and $480 million (limited benefits); for Medicaid alone, the costs are $1.43 and $1.17 billion, respectively. Results were sensitive to awareness of serostatus, highly active antiretroviral therapy cost, and participation rate. Strategies for federal cost neutrality include Medicaid HIV drug price reductions as low as 9% and private insurance buy-ins. Conclusions. Expansion of the Medicaid eligibility to increase access to antiretroviral therapy would have substantial health benefits at affordable costs. PMID:11527783

  5. Development of the Zebra load region for increased capability plasma diagnostics and improved Leopard laser access

    NASA Astrophysics Data System (ADS)

    Astanovitskiy, Alexey; Presura, R.; Ivanov, V. V.; Haboub, A.; Plachaty, C.; Kindel, J. M.

    2008-11-01

    A new geometry for the load area in the Zebra (1MA pulse generator) is developed. It will form the basis for future experiments requiring Leopard (1057nm, 50TW laser) to Zebra coupling and give extended capability to z-pinch diagnostics. This required the development of a new current return, which allows laser access and installation of the OD 4'' parabolic mirror for the x-ray radiography, isochoric heating and magnetized plasma experiments, and accommodates wire-array z-pinch loads, to which the laser may then be coupled. In addition, this configuration allows diagnostics access close to the plasma, leading to a significant increase of the spatial resolution for imaging of z-pinches, as well as the photon flux in imaging and spectroscopy of laser produced plasmas. These diagnostics will allow coupling of the Leopard beam for x-ray laser probing of the pinch plasma and we will test point-projection x-ray backlighting of the pinch plasma.

  6. Finding death in meaninglessness: Evidence that death-thought accessibility increases in response to meaning threats.

    PubMed

    Webber, David; Zhang, Rui; Schimel, Jeff; Blatter, Jamin

    2016-03-01

    The meaning maintenance model proposes that violations to one's expectations will cause subsequent meaning restoration. In attempts to distinguish meaning maintenance mechanisms from mechanisms of terror management, previous research has failed to find increased death-thought accessibility (DTA) in response to various meaning threats. The present research suggests that this failure may have resulted from methodological differences in the way researchers measured DTA. Studies 1a and 1b found that by replacing this method with a standard method employed when studying worldview and self-esteem threats, DTA increased in response to two different meaning violations. Study 2 found increased DTA, but only among individuals high in personal need for structure, when using this standard DTA procedure, but not when using the procedure taken from previous meaning maintenance studies. Interestingly, these studies did not find increased meaning restoration, so an additional study (Study 3) was designed to provide a theoretically informed examination of this null effect. A meaning restoration effect was observed after removing the standard DTA assessment procedure, but only among participants high in personal need for structure. Implications for the threat-compensation literature are discussed.

  7. 47 CFR 1.1403 - Duty to provide access; modifications; notice of removal, increase or modification; petition for...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... increase in pole attachment rates; or (3) Any modification of facilities other than routine maintenance or... reasons of safety, reliability and generally applicable engineering purposes. (b) Requests for access to a... and information relate to a denial of access for reasons of lack of capacity, safety, reliability...

  8. Innovative Low Cost Science Education Technology Tools: Increasing Access to Science for All

    NASA Astrophysics Data System (ADS)

    Noel-Storr, J.; Cole, B. N.

    2012-08-01

    We present three low cost educational technology tools that have been developed by the Rochester Institute of Technology Insight Lab. Our technology tools are designed with cost and "user-tinkerability" in mind, to increase the potential for technology-rich access to scientific data to be in the hands of a much larger slice of the population. The three tools presented are the Planeterrainium - A digital interactive floor projection system allowing users to explore the planets in 3D; the Digital Solar Explorer - a 5 foot inflatable sphere designed to allow for the exploration of solar imagery; and the Scube - a digital immersive tentware system. We describe projects that involve both undergraduate and high school students in the development of content for these systems, encouraging the growth of both scientific and technological literacy in the process.

  9. Compact radiation sources for increased access to high brightness x-rays

    NASA Astrophysics Data System (ADS)

    O'Shea, Finn Henry

    The successful operation of the x-ray free electron lasers at LCLS and SACLA are a boon for science. The increase in brightness of 10 orders of magnitude over synchrotron sources as well as the sub-picosecond time profile of the x-rays are opening new avenues of research in fields ranging from biology to solid state physics. However, synchrotrons and free electron lasers that produce x-rays are expensive, with price tags that measured hundreds of millions. Further, the standard unit of measure for the scale of these sources is kilometers. The sheer size and prohibitive cost of these devices means that such sources are out of the reach of universities and smaller laboratories. The focus of this dissertation is in increasing access to x-ray sources by making them both smaller and, perhaps more importantly, cheaper. Current limitations to source size reduction are discussed which leads to the conclusion that smaller x-rays sources require short period undulators. In this context, two approaches to increasing access to x-rays are covered. The first is direct decrease in the period length of undulators through more advanced design and materials. This path begins with a discussion of the design and construction of a 9 mm period prototype. An analysis of the benefits of such a device, in reduced undulator and accelerator lengths at existing free electron lasers, is explored. And finally, the operation of the undulator in a realistic scenario is experimentally explored in a scaled experiment at optical frequencies. The second method for decreasing the period length of the light source is to replace the undulator with a laser, making an inverse Compton scattering source. The relationship between undulator radiation and the inverse Compton scattering process is examined, as well as the characteristics of the source itself. Lastly, as a demonstration of the function of the inverse Compton scattering source at Brookhaven National Laboratory as a diagnostic tool rather than an

  10. Increasing access to health care: examination of hospital community benefits and free care programs.

    PubMed

    Giffords, Elissa D; Wenze, Linda; Weiss, David M; Kass, Donna; Guercia, Rosemarie

    2005-08-01

    The present study explored hospital community benefits and free care programs at seven hospitals in Nassau and Suffolk counties in Long Island, NewYork. There were two components to this project: (1) assessment of information regarding the availability of free care and (2) an analysis of the community benefits information filed with state regulatory offices. Results show that not one of the seven hospitals consistently informed surveyors that free care was available to low-income, uninsured people. Surveyors had difficulty obtaining written free care policies. The article concludes with suggestions for government agencies, hospital administrators, social workers, and other advocates on how to get involved in efforts to increase access to health care for the uninsured population.

  11. [Estimation of rice LAI by using NDVI at different spectral bandwidths].

    PubMed

    Wang, Fu-min; Huang, Jing-feng; Tang, Yan-lin; Wang, Xiu-zhen

    2007-11-01

    The canopy hyperspectral reflectance data of rice at its different development stages were collected from field measurement, and the corresponding NDVIs as well as the correlation coefficients of NDVIs and LAI were computed at extending bandwidth of TM red and near-infrared (NIR) spectra. According to the variation characteristics of best fitted R2 with spectral bandwidth, the optimal bandwidth was determined. The results showed that the correlation coefficients of LAI and ND-VI and the maximum R2 of the best fitted functions at different spectral bandwidths had the same variation trend, i.e., decreased with increasing bandwidth when the bandwidth was less than 60 nm. However, when the bandwidth was beyond 60 nm, the maximum R2 somewhat fluctuated due to the effect of NIR. The analysis of R2 variation with bandwidth indicated that 15 nm was the optimal bandwidth for the estimation of rice LAI by using NDVI.

  12. Adaptive broadcasting mechanism for bandwidth allocation in mobile services.

    PubMed

    Horng, Gwo-Jiun; Wang, Chi-Hsuan; Chou, Chih-Lun

    2014-01-01

    This paper proposes a tree-based adaptive broadcasting (TAB) algorithm for data dissemination to improve data access efficiency. The proposed TAB algorithm first constructs a broadcast tree to determine the broadcast frequency of each data and splits the broadcast tree into some broadcast wood to generate the broadcast program. In addition, this paper develops an analytical model to derive the mean access latency of the generated broadcast program. In light of the derived results, both the index channel's bandwidth and the data channel's bandwidth can be optimally allocated to maximize bandwidth utilization. This paper presents experiments to help evaluate the effectiveness of the proposed strategy. From the experimental results, it can be seen that the proposed mechanism is feasible in practice.

  13. Low Bandwidth Robust Controllers for Flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1993-01-01

    Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

  14. Low bandwidth robust controllers for flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1993-01-01

    Through throttle manipulations, engine thrust can be used for emergency flight control for multi-engine aircraft. Previous study by NASA Dryden has shown the use of throttles for emergency flight control to be very difficult. In general, manual fly-by-throttle is extremely difficult - with landing almost impossible, but control augmentation makes runway landings feasible. Flight path control using throttles-only to achieve safe emergency landing for a large jet transport airplane, Boeing 720, was investigated using Quantitative Feedback Theory (QFT). Results were compared to an augmented control developed in a previous simulation study. The control augmentation corrected the unsatisfactory open-loop characteristics by increasing system bandwidth and damping, but increasing the control bandwidth substantially proved very difficult. The augmented pitch control is robust under no or moderate turbulence. The augmented roll control is sensitive to configuration changes.

  15. Steel Industry Energy Bandwidth Study

    SciTech Connect

    none,

    2004-10-01

    ITP conducted a study on energy use and potential savings, or "bandwidth" study, in major steelmaking processes. Intended to provide a realistic estimate of the potential amount of energy that can be saved in an industrial process, the "bandwidth" refers to the difference between the amount of energy that would be consumed in a process using commercially available technology versus the minimum amount of energy needed to achieve those same results based on the 2nd law of thermodynamics. The Steel Industry Energy Bandwidth Study (PDF 133 KB) also estimates steel industry energy use in the year 2010, and uses that value as a basis for comparison against the minimum requirements. This energy savings opportunity for 2010 will aid focus on longer term R&D.

  16. New Neighborhood Grocery Store Increased Awareness Of Food Access But Did Not Alter Dietary Habits Or Obesity

    PubMed Central

    Cummins, Steven; Flint, Ellen; Matthews, Stephen A.

    2014-01-01

    Current national and local policies to improve diet in low-income US populations include increasing physical access to grocery stores and supermarkets in underserved neighbourhoods. Using a prospective controlled quasi-experimental design we evaluate the impact on Body Mass Index, fruit and vegetable intake and perceptions of food access, of increasing neighborhood supermarket provision in one community in Philadelphia. This increase in provision was one part of the wider public-private Pennsylvania Fresh Food Financing Initiative. The intervention moderately increased perceptions of food access, but did not lead to changes in fruit and vegetable intake or BMI. This suggests that a perception-action `gap' may exist. The effectiveness of interventions to improve physical access to food by encouraging supermarkets to locate in underserved areas therefore remains uncertain. Replication of findings in other settings is urgently required. PMID:24493772

  17. Mining Industry Energy Bandwidth Study

    SciTech Connect

    none,

    2007-07-01

    The Industrial Technologies Program (ITP) relies on analytical studies to identify large energy reduction opportunities in energy-intensive industries and uses these results to guide its R&D portfolio. The energy bandwidth illustrates the total energy-saving opportunity that exists in the industry if the current processes are improved by implementing more energy-efficient practices and by using advanced technologies. This bandwidth analysis report was conducted to assist the ITP Mining R&D program in identifying energy-saving opportunities in coal, metals, and mineral mining. These opportunities were analyzed in key mining processes of blasting, dewatering, drilling, digging, ventilation, materials handling, crushing, grinding, and separations.

  18. Germanium photodetector with 60 GHz bandwidth using inductive gain peaking.

    PubMed

    Novack, Ari; Gould, Mike; Yang, Yisu; Xuan, Zhe; Streshinsky, Matthew; Liu, Yang; Capellini, Giovanni; Lim, Andy Eu-Jin; Lo, Guo-Qiang; Baehr-Jones, Tom; Hochberg, Michael

    2013-11-18

    Germanium-on-silicon photodetectors have been heavily investigated in recent years as a key component of CMOS-compatible integrated photonics platforms. It has previously been shown that detector bandwidths could theoretically be greatly increased with the incorporation of a carefully chosen inductor and capacitor in the photodetector circuit. Here, we show the experimental results of such a circuit that doubles the detector 3dB bandwidth to 60 GHz. These results suggest that gain peaking is a generally applicable tool for increasing detector bandwidth in practical photonics systems without requiring the difficult process of lowering detector capacitance.

  19. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Emission bandwidth. 95.633 Section 95.633... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized bandwidth (maximum permissible bandwidth of a transmission) for emission type H1D, J1D, R1D, H3E, J3E or...

  20. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Emission bandwidth. 95.633 Section 95.633... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized bandwidth (maximum permissible bandwidth of a transmission) for emission type H1D, J1D, R1D, H3E, J3E or...

  1. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Emission bandwidth. 95.633 Section 95.633... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized bandwidth (maximum permissible bandwidth of a transmission) for emission type H1D, J1D, R1D, H3E, J3E or...

  2. Increasing Access to Science Oriented Education Programmes in Tertiary Institutions in Ghana through Distance Education

    ERIC Educational Resources Information Center

    Osei, C. K.; Mensah, J. A.

    2014-01-01

    There is emphasis in the educational policy of Ghana for the promotion of Distance Education programmes to widen access to education at all levels and facilitate human resource development. This study examined the level of access and challenges faced by learners in science oriented programmes offered by distance in the Kwame Nkrumah University of…

  3. Sound source localization identification accuracy: bandwidth dependencies.

    PubMed

    Yost, William A; Zhong, Xuan

    2014-11-01

    Sound source localization accuracy using a sound source identification task was measured in the front, right quarter of the azimuth plane as rms (root-mean-square) error (degrees) for stimulus conditions in which the bandwidth (1/20 to 2 octaves wide) and center frequency (250, 2000, 4000 Hz) of 200-ms noise bursts were varied. Tones of different frequencies (250, 2000, 4000 Hz) were also used. As stimulus bandwidth increases, there is an increase in sound source localization identification accuracy (i.e., rms error decreases). Wideband stimuli (>1 octave wide) produce best sound source localization accuracy (~6°-7° rms error), and localization accuracy for these wideband noise stimuli does not depend on center frequency. For narrow bandwidths (<1 octave) and tonal stimuli, accuracy does depend on center frequency such that highest accuracy is obtained for low-frequency stimuli (centered on 250 Hz), worse accuracy for mid-frequency stimuli (centered on 2000 Hz), and intermediate accuracy for high-frequency stimuli (centered on 4000 Hz).

  4. Weapon use increases the severity of domestic violence but neither weapon use nor firearm access increases the risk or severity of recidivism.

    PubMed

    Folkes, Stephanie E F; Hilton, N Zoe; Harris, Grant T

    2013-04-01

    Use of weapons is a risk factor for domestic violence severity, especially lethality. It is not clear, however, whether access to firearms itself increases assault severity, or whether it is characteristic of a subgroup of offenders who are more likely to commit severe and repeated domestic assault. This reanalysis of 1,421 police reports of domestic violence by men found that 6% used a weapon during the assault and 8% had access to firearms. We expected that firearm use would be rare compared to other weapons and that actual weapon use rather than firearm access would increase the severity of domestic assaults. Firearm access was associated with assault severity, but this was mostly attributable to use of nonfirearm weapons. Weapon use was associated with older age, lower education, and relationship history as well as to assault severity. Victims were most concerned about future assaults following threats and actual injuries. Although firearm access and weapon use were related to actuarial risk of domestic violence recidivism, neither predicted the occurrence or severity of recidivism. We conclude that, consistent with previous research in the United States and Canada, firearm use in domestic violence is uncommon even among offenders with known firearm access. Weapon use is characteristic of a subgroup of offenders who commit more severe domestic violence, and seizure of weapons may be an effective intervention.

  5. Black holes, bandwidths and Beethoven

    NASA Astrophysics Data System (ADS)

    Kempf, Achim

    2000-04-01

    It is usually believed that a function φ(t) whose Fourier spectrum is bounded can vary at most as fast as its highest frequency component ωmax. This is, in fact, not the case, as Aharonov, Berry, and others drastically demonstrated with explicit counterexamples, so-called superoscillations. It has been claimed that even the recording of an entire Beethoven symphony can occur as part of a signal with a 1 Hz bandwidth. Bandlimited functions also occur as ultraviolet regularized fields. Their superoscillations have been suggested, for example, to resolve the trans-Planckian frequencies problem of black hole radiation. Here, we give an exact proof for generic superoscillations. Namely, we show that for every fixed bandwidth there exist functions that pass through any finite number of arbitrarily prespecified points. Further, we show that, in spite of the presence of superoscillations, the behavior of bandlimited functions can be characterized reliably, namely through an uncertainty relation: The standard deviation ΔT of samples φ(tn) taken at the Nyquist rate obeys ΔT>=1/4ωmax. This uncertainty relation generalizes to variable bandwidths. For ultraviolet regularized fields we identify the bandwidth as the in general spatially variable finite local density of degrees of freedom.

  6. Retail medical clinics: increasing access to low cost medical care amongst a developing legal environment.

    PubMed

    Schleiter, Kristin E

    2010-01-01

    Retail medical clinics are an innovation in health care with the potential to increase access to low-cost basic health care services while changing the delivery model for routine, non-urgent medical care. However, the few states that attempted to directly regulate retail medical clinics have been met with criticism by the FTC due to the proposed legislations' anticompetitive undertones. The relationship between retail medical clinics and the host stores or pharmacies that house them has the potential to spark fraud and abuse concerns. Retail medical clinics must abide by state-specific regulation on scope of practice of the various mid-level practitioners who work for the clinics, particularly to minimize exposure to litigation and keep within the clinics' intended purpose of a supplement to primary care physician offices. The author concludes that the consumer benefits of cost and convenience, combined with the potential for growth and expanded consumer base from a retailers' perspective, make the legal challenge inherent in running a retail medical clinic well worth the effort.

  7. Cost of increasing access to artemisinin combination therapy: the Cambodian experience

    PubMed Central

    Yeung, Shunmay; Van Damme, Wim; Socheat, Duong; White, Nicholas J; Mills, Anne

    2008-01-01

    Background Malaria-endemic countries are switching antimalarial drug policy from cheap ineffective monotherapies to artemisinin combination therapies (ACTs) for the treatment of Plasmodium falciparum malaria and the global community are considering setting up a global subsidy to fund their purchase. However, in order to ensure that ACTs are correctly used and are accessible to the poor and remote communities who need them, specific interventions will be necessary and the additional costs need to be considered. Methods This paper presents an incremental cost analysis of some of these interventions in Cambodia, the first country to change national antimalarial drug policy to an ACT of artesunate and mefloquine. These costs include the cost of rapid diagnostic tests (RDTs), the cost of blister-packaging the drugs locally and the costs of increasing access to diagnosis and treatment to remote communities through malaria outreach teams (MOTs) and Village Malaria Workers (VMW). Results At optimum productive capacity, the cost of blister-packaging cost under $0.20 per package but in reality was significantly more than this because of the low rate of production. The annual fixed cost (exclusive of RDTs and drugs) per capita of the MOT and VMW schemes was $0.44 and $0.69 respectively. However because the VMW scheme achieved a higher rate of coverage than the MOT scheme, the cost per patient treated was substantially lower at $5.14 compared to $12.74 per falciparum malaria patient treated. The annual cost inclusive of the RDTs and drugs was $19.31 for the MOT scheme and $11.28 for the VMW scheme given similar RDT positivity rates of around 22% and good provider compliance to test results. Conclusion In addition to the cost of ACTs themselves, substantial additional investments are required in order to ensure that they reach the targeted population via appropriate delivery systems and to ensure that they are used appropriately. In addition, differences in local conditions, in

  8. Bandwidth efficient coding for satellite communications

    NASA Technical Reports Server (NTRS)

    Lin, Shu; Costello, Daniel J., Jr.; Miller, Warner H.; Morakis, James C.; Poland, William B., Jr.

    1992-01-01

    An error control coding scheme was devised to achieve large coding gain and high reliability by using coded modulation with reduced decoding complexity. To achieve a 3 to 5 dB coding gain and moderate reliability, the decoding complexity is quite modest. In fact, to achieve a 3 dB coding gain, the decoding complexity is quite simple, no matter whether trellis coded modulation or block coded modulation is used. However, to achieve coding gains exceeding 5 dB, the decoding complexity increases drastically, and the implementation of the decoder becomes very expensive and unpractical. The use is proposed of coded modulation in conjunction with concatenated (or cascaded) coding. A good short bandwidth efficient modulation code is used as the inner code and relatively powerful Reed-Solomon code is used as the outer code. With properly chosen inner and outer codes, a concatenated coded modulation scheme not only can achieve large coding gains and high reliability with good bandwidth efficiency but also can be practically implemented. This combination of coded modulation and concatenated coding really offers a way of achieving the best of three worlds, reliability and coding gain, bandwidth efficiency, and decoding complexity.

  9. A public aid clinic prototype: utilizing a dental hygiene educational facility to increase access to care.

    PubMed

    Maurizio, Sandra J; DeMattei, Ronda; Meyer, Jennifer; Cotner, Danna

    2003-01-01

    Few dentists in a rural Midwestern community participate in providing oral health care to public aid recipients. In response, faculty at a baccalaureate degree dental hygiene program located at Southern illinois University, Carbondale (SIUC) proposed, developed, and implemented the Heartland Dental Clinic to serve Medicaid participants. The unique program utilizes existing facilities, staff, and students to provide comprehensive oral health care to underserved populations. The state awarded a small grant to cover start-up costs. Two dental units were upgraded with fiber optics to allow restorative procedures. Dental hygiene students provide intake examinations and preventive care, while a staff dentist provides restorative care, dentures, and examinations. Dental technology students and faculty fabricate prostheses. A part-time clinic manager facilitates communication, patient scheduling, and billing. Two local Rotary Club members volunteer as receptionists for the clinic on the one evening per week that the clinic operates. The Rotary Club purchased educational pamphlets, a television/VCR, videotapes, and two signs for the clinic. By locating the clinic in the existing SIUC facility and utilizing dental hygiene students, a staff dentist, volunteer receptionists and dentists, student workers, and health care management interns, the clinic overhead costs have been kept to a minimum. The clinic provides a unique opportunity for dental hygiene students to experience firsthand scheduling, billing, and treating public aid patients while providing patients with an additional source for oral health care. The Heartland Dental Clinic model represents a cost effective method for increasing oral health access to underserved populations while also benefiting students in an educational program.

  10. RAID Disk Arrays for High Bandwidth Applications

    NASA Technical Reports Server (NTRS)

    Moren, Bill

    1996-01-01

    High bandwidth applications require large amounts of data transferred to/from storage devices at extremely high data rates. Further, these applications often are 'real time' in which access to the storage device must take place on the schedule of the data source, not the storage. A good example is a satellite downlink - the volume of data is quite large and the data rates quite high (dozens of MB/sec). Further, a telemetry downlink must take place while the satellite is overhead. A storage technology which is ideally suited to these types of applications is redundant arrays of independent discs (RAID). Raid storage technology, while offering differing methodologies for a variety of applications, supports the performance and redundancy required in real-time applications. Of the various RAID levels, RAID-3 is the only one which provides high data transfer rates under all operating conditions, including after a drive failure.

  11. 47 CFR 1.1403 - Duty to provide access; modifications; notice of removal, increase or modification; petition for...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Attachment Complaint Procedures § 1.1403 Duty to provide access; modifications; notice of removal, increase... cable television system operator's of telecommunications carrier's pole attachment agreement; (2) Any increase in pole attachment rates; or (3) Any modification of facilities other than routine maintenance...

  12. Increasing College Enrollment among Low- and Moderate-Income Families: An Intervention to Improve Information and Access to Financial Aid

    ERIC Educational Resources Information Center

    Bettinger, Eric P.; Long, Bridget Terry; Oreopoulos, Philip

    2007-01-01

    Higher education plays an increasingly important role in helping individuals attain social and economic success. Yet, despite decades of financial aid policy, substantial gaps in college access remain by income level and race. One major impediment to increasing college enrollment among low-income students is the lack of information about financial…

  13. Bandwidth broadening for stripline circulator

    NASA Astrophysics Data System (ADS)

    Chao, Hsien-Wen; Wu, Shi-Yao; Chang, Tsun-Hsu

    2017-02-01

    This work provides a detailed analysis and simulation to demonstrate how to broaden the operating bandwidth of a circulator. A double-Y junction circulator is designed, and the shape of the central stripline is optimized with the knowledge of a modified equation. The equation predicts two resonant conditions. The overlapping of the two resonant conditions jointly constitutes the broad bandwidth. The bias magnetic field is simulated and then used in full electromagnetic-wave simulation. The designed circulator was fabricated in the S-band for communication purpose. The measured results agree very well with simulation. The overall operation range is from 1643 to 2027 MHz with the insertion loss less than 0.35 dB, reflection, and isolation better than 20 dB. The mechanism will be discussed.

  14. Values, inter-attitudinal structure, and attitude change: value accessibility can increase a related attitude's resistance to change.

    PubMed

    Blankenship, Kevin L; Wegener, Duane T; Murray, Renee A

    2015-12-01

    Accessibility is one of the most basic structural properties of an attitude and an important factor to consider in attitude strength. Despite its importance, relatively little work has examined the role of attitude accessibility in an inter-attitudinal context, particularly as it relates to the strength of related attitudes in the network. The present research examines accessibility as a property of one attitude (toward an abstract goal or end-state, that is, a value) that might influence the strength of a different but related attitude (toward a social policy conceptually related to the value). In Study 1, a highly accessible evaluative component of a value increased resistance to change of attitudes and behavioral intentions toward a social policy related to that value. Similarly, a manipulation of value accessibility (Studies 2 and 3) led to increased resistance of attitudes and behavioral intentions toward a social policy related to that value. Implications for the role of accessibility in inter-attitudinal strength are discussed.

  15. Activation of the attachment system in adulthood: threat-related primes increase the accessibility of mental representations of attachment figures.

    PubMed

    Mikulincer, Mario; Gillath, Omri; Shaver, Phillip R

    2002-10-01

    Three studies explored the effects of subliminal threat on the activation of representations of attachment figures. This accessibility was measured in a lexical decision task and a Stroop task following threat- or neutral-word primes, and was compared with the accessibility of representations of other close persons, known but not close persons, and unknown persons. Participants also reported on their attachment style. Threat primes led to increased accessibility of representations of attachment figures. This effect was specific to attachment figures and was replicated across tasks and experiments. Attachment anxiety heightened accessibility of representations of attachment figures even in neutral contexts, whereas attachment avoidance inhibited this activation when the threat prime was the word separation. These effects were not, explained by trait anxiety. The discussion focuses on the dynamics of attachment-system activation in adulthood.

  16. Tunable-Bandwidth Filter System

    NASA Technical Reports Server (NTRS)

    Bailey, John W.

    2004-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS, was shown to be capable of spectral sampling of images in the visible range over a 200 nm spectral range with a spectral resolution of 30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses incoming light

  17. Tunable-Bandwidth Filter System

    NASA Technical Reports Server (NTRS)

    Aye, Tin; Yu, Kevin; Dimov, Fedor; Savant, Gajendra

    2006-01-01

    A tunable-bandwidth filter system (TBFS), now undergoing development, is intended to be part of a remote-sensing multispectral imaging system that will operate in the visible and near infrared spectral region (wavelengths from 400 to 900 nm). Attributes of the TBFS include rapid tunability of the pass band over a wide wavelength range and high transmission efficiency. The TBFS is based on a unique integration of two pairs of broadband Raman reflection holographic filters with two rotating spherical lenses. In experiments, a prototype of the TBFS was shown to be capable of spectral sampling of images in the visible range over a 200-nm spectral range with a spectral resolution of .30 nm. The figure depicts the optical layout of a prototype of the TBFS as part of a laboratory multispectral imaging system for the spectral sampling of color test images in two orthogonal polarizations. Each pair of broadband Raman reflection holographic filters is mounted at an equatorial plane between two halves of a spherical lens. The two filters in each pair are characterized by steep spectral slopes (equivalently, narrow spectral edges), no ripple or side lobes in their pass bands, and a few nanometers of non-overlapping wavelength range between their pass bands. Each spherical lens and thus the filter pair within it is rotated in order to rapidly tune its pass band. The rotations of the lenses are effected by electronically controlled, programmable, high-precision rotation stages. The rotations are coordinated by electronic circuits operating under overall supervision of a personal computer in order to obtain the desired variation of the overall pass bands with time. Embedding the filters inside the spherical lenses increases the range of the hologram incidence angles, making it possible to continuously tune the pass and stop bands of the filters over a wider wavelength range. In addition, each spherical lens also serves as part of the imaging optics: The telephoto lens focuses

  18. A novel dynamic wavelength bandwidth allocation scheme over OFDMA PONs

    NASA Astrophysics Data System (ADS)

    Yan, Bo; Guo, Wei; Jin, Yaohui; Hu, Weisheng

    2011-12-01

    With rapid growth of Internet applications, supporting differentiated service and enlarging system capacity have been new tasks for next generation access system. In recent years, research in OFDMA Passive Optical Networks (PON) has experienced extraordinary development as for its large capacity and flexibility in scheduling. Although much work has been done to solve hardware layer obstacles for OFDMA PON, scheduling algorithm on OFDMA PON system is still under primary discussion. In order to support QoS service on OFDMA PON system, a novel dynamic wavelength bandwidth allocation (DWBA) algorithm is proposed in this paper. Per-stream QoS service is supported in this algorithm. Through simulation, we proved our bandwidth allocation algorithm performs better in bandwidth utilization and differentiate service support.

  19. From Open Content to Open Course Models: Increasing Access and Enabling Global Participation in Higher Education

    ERIC Educational Resources Information Center

    Morgan, Tannis; Carey, Stephen

    2009-01-01

    Two of the major challenges to international students' right of access to higher education are geographical/economic isolation and academic literacy in English (Carey, 1999; Hamel, 2007). The authors propose that adopting open course models in traditional universities, through blended or online delivery, can offer benefits to the institutions and…

  20. Nonprofits Partnering with Postsecondary Institutions to Increase Low-Income Student Access

    ERIC Educational Resources Information Center

    Kezar, Adrianna; Lester, Jaime; Yang, Hannah

    2010-01-01

    This article reports on a three year case study and interview project of a federal initiative to help low income students access college called individual development accounts (IDA). The study focused on partnership development between community agencies that offer IDAs and postsecondary institutions, examining challenges and facilitators. A set…

  1. Increasing Access to College: Extending Possibilities for All Students. SUNY Series, Frontiers in Education.

    ERIC Educational Resources Information Center

    Tierney, William G., Ed.; Hagedorn, Linda Serra, Ed.

    This collection of papers examines pre-college enrichment programs that offer a specific remedy to the problem of low income and underrepresented students' access to higher education. The 10 papers are: (1) "Pre-College Outreach Programs: A National Perspective" (Watson Scott Swail and Laura W. Perna); (2) "The Relationship between…

  2. Access and privacy rights using web security standards to increase patient empowerment.

    PubMed

    Falcão-Reis, Filipa; Costa-Pereira, Altamiro; Correia, Manuel E

    2008-01-01

    Electronic Health Record (EHR) systems are becoming more and more sophisticated and include nowadays numerous applications, which are not only accessed by medical professionals, but also by accounting and administrative personnel. This could represent a problem concerning basic rights such as privacy and confidentiality. The principles, guidelines and recommendations compiled by the OECD protection of privacy and trans-border flow of personal data are described and considered within health information system development. Granting access to an EHR should be dependent upon the owner of the record; the patient: he must be entitled to define who is allowed to access his EHRs, besides the access control scheme each health organization may have implemented. In this way, it's not only up to health professionals to decide who have access to what, but the patient himself. Implementing such a policy is walking towards patient empowerment which society should encourage and governments should promote. The paper then introduces a technical solution based on web security standards. This would give patients the ability to monitor and control which entities have access to their personal EHRs, thus empowering them with the knowledge of how much of his medical history is known and by whom. It is necessary to create standard data access protocols, mechanisms and policies to protect the privacy rights and furthermore, to enable patients, to automatically track the movement (flow) of their personal data and information in the context of health information systems. This solution must be functional and, above all, user-friendly and the interface should take in consideration some heuristics of usability in order to provide the user with the best tools. The current official standards on confidentiality and privacy in health care, currently being developed within the EU, are explained, in order to achieve a consensual idea of the guidelines that all member states should follow to transfer

  3. Access to bone densitometry increases general practitioners' prescribing for osteoporosis in steroid treated patients

    PubMed Central

    Dolan, A; Koshy, E; Waker, M; Goble, C

    2004-01-01

    Background: Availability of access to bone densitometry in the UK varies widely and there are concerns as to appropriate prescribing. Studies suggest inadequate use of osteoporosis prophylaxis in steroid users, despite recent guidelines. Objective: To examine in a case-control study whether access to bone densitometry affects GPs' osteoporosis prescribing in high risk steroid users. Method: 10 general practices were included, five from primary care trusts (PCTs) with access to bone densitometry and five with limited access. Patients receiving prednisolone for >3 months were identified by database search. Patients receiving no prophylaxis other than calcium and vitamin D (Ca/D) were subsequently included. Appropriate patients in five practices were offered DXA scan (cases) and review. Patients in practices without access to scans (controls) were reviewed. GPs' opinions leading to treatment were sought by structured questionnaire. Results: 132 (0.12%) patients were receiving prednisolone for ⩾3 months, but no osteoporosis prophylaxis other than Ca/D. Pre-study prophylaxis ranged from 18 to 36%. Of 48 patients scanned, 21 (44%) were abnormal and 18 (38%) received new treatment. 13/44 (30%) controls received new treatment. 10/21 (48%) with abnormal scans started a bisphosphonate, compared with 7/44 (16%) controls (RR = 3, p = 0.004). No difference in risk factors for fracture was found in treated and untreated controls. Conclusions: GPs were three times more likely to start potent osteoporosis treatment after abnormal scans than GPs relying on clinical information. In practice, risk factors were not adequately assessed. Database searches may identify patients needing osteoporosis prophylaxis; however, DXA enables more appropriate patient treatment. PMID:14722208

  4. Dynamic Bandwidth Allocation with Effective Utilization of Polling Interval over WDM/TDM PON

    NASA Astrophysics Data System (ADS)

    Ni, Cuiping; Gan, Chaoqin; Gao, Ziyue

    2014-12-01

    WDM/TDM (wavelength-division multiplexing/time-division multiplexing) PON (passive optical network) appears to be an attractive solution for the next generation optical access networks. Dynamic bandwidth allocation (DBA) plays a crucial role in efficiently and fairly allocating the bandwidth among all users in WDM/TDM PON. In this paper, two dynamic bandwidth allocation schemes (DBA1 and DBA2) are proposed to eliminate the idle time of polling cycles (i.e. polling interval), improve bandwidth utilization and make full use of bandwidth resources. The two DBA schemes adjust the time slot of sending request information and make fair scheduling among users to achieve the effective utilization of polling interval in WDM/TDM PON. The simulation and theoretical analyses verify that the proposed schemes outperform the conventional DBA scheme. We also make comparisons between the two schemes in terms of bandwidth utilization and average packet delay to further demonstrate the effectiveness of the scheme of DBA2.

  5. High bandwidth deflection readout for atomic force microscopes.

    PubMed

    Steininger, Juergen; Bibl, Matthias; Yoo, Han Woong; Schitter, Georg

    2015-10-01

    This contribution presents the systematic design of a high bandwidth deflection readout mechanism for atomic force microscopes. The widely used optical beam deflection method is revised by adding a focusing lens between the cantilever and the quadrant photodetector (QPD). This allows the utilization of QPDs with a small active area resulting in an increased detection bandwidth due to the reduced junction capacitance. Furthermore the additional lens can compensate a cross talk between a compensating z-movement of the cantilever and the deflection readout. Scaling effects are analyzed to get the optimal spot size for the given geometry of the QPD. The laser power is tuned to maximize the signal to noise ratio without limiting the bandwidth by local saturation effects. The systematic approach results in a measured -3 dB detection bandwidth of 64.5 MHz at a deflection noise density of 62fm/√Hz.

  6. Algorithms and Requirements for Measuring Network Bandwidth

    SciTech Connect

    Jin, Guojun

    2002-12-08

    This report unveils new algorithms for actively measuring (not estimating) available bandwidths with very low intrusion, computing cross traffic, thus estimating the physical bandwidth, provides mathematical proof that the algorithms are accurate, and addresses conditions, requirements, and limitations for new and existing algorithms for measuring network bandwidths. The paper also discusses a number of important terminologies and issues for network bandwidth measurement, and introduces a fundamental parameter -Maximum Burst Size that is critical for implementing algorithms based on multiple packets.

  7. Improving the Bandwidth Selection in Kernel Equating

    ERIC Educational Resources Information Center

    Andersson, Björn; von Davier, Alina A.

    2014-01-01

    We investigate the current bandwidth selection methods in kernel equating and propose a method based on Silverman's rule of thumb for selecting the bandwidth parameters. In kernel equating, the bandwidth parameters have previously been obtained by minimizing a penalty function. This minimization process has been criticized by practitioners…

  8. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its upper frequency limits, the mean powers radiated are each equal...

  9. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its upper frequency limits, the mean powers radiated are each equal...

  10. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Emissions § 2.202 Bandwidths. (a) Occupied bandwidth. The frequency bandwidth such that, below its lower and above its upper frequency limits, the mean powers radiated are each equal...

  11. Single exposure to disclaimers on airbrushed thin ideal images increases negative thought accessibility.

    PubMed

    Selimbegović, Leila; Chatard, Armand

    2015-01-01

    Disclaimers on airbrushed thin ideal images can attract attention to the thin ideal standard promoted by the advertisements, which can be damaging rather than helpful. In this study, 48 female college students were exposed to a thin ideal image including a disclaimer, a neutral sentence, or nothing. Two weeks and two months after this, they were again exposed to the same image but with no accompanying text in any of the conditions. Negative thought accessibility was assessed three times, after each exposure to the thin-ideal image, using reaction time measures. Participants randomly assigned to the disclaimer condition systematically showed greater accessibility of negative thoughts than those in the other two conditions, irrespective of the time of measurement. These results suggest that disclaimers on airbrushed images may have some counter-productive effects by accentuating the problems that they precisely aim to address.

  12. TRIPS, the Doha Declaration and increasing access to medicines: policy options for Ghana

    PubMed Central

    Cohen, JC; Gyansa-Lutterodt, M; Torpey, K; Esmail, LC; Kurokawa, G

    2005-01-01

    There are acute disparities in pharmaceutical access between developing and industrialized countries. Developing countries make up approximately 80% of the world's population but only represent approximately 20% of global pharmaceutical consumption. Among the many barriers to drug access are the potential consequences of the Trade Related Aspects of Intellectual Property Rights (TRIPS) Agreement. Many developing countries have recently modified their patent laws to conform to the TRIPS standards, given the 2005 deadline for developing countries. Safeguards to protect public health have been incorporated into the TRIPS Agreement; however, in practice governments may be reluctant to exercise such rights given concern about the international trade and political ramifications. The Doha Declaration and the recent Decision on the Implementation of Paragraph 6 of the Doha Declaration on the TRIPS Agreement and Public Health may provide more freedom for developing countries in using these safeguards. This paper focuses on Ghana, a developing country that recently changed its patent laws to conform to TRIPS standards. We examine Ghana's patent law changes in the context of the Doha Declaration and assess their meaning for access to drugs of its population. We discuss new and existing barriers, as well as possible solutions, to provide policy-makers with lessons learned from the Ghanaian experience. PMID:16336685

  13. Increasing access to Latin American social medicine resources: a preliminary report*

    PubMed Central

    Buchanan, Holly Shipp; Waitzkin, Howard; Eldredge, Jonathan; Davidson, Russ; Iriart, Celia; Teal, Janis

    2003-01-01

    Purpose: This preliminary report describes the development and implementation of a project to improve access to literature in Latin American social medicine (LASM). Methods: The University of New Mexico project team collaborated with participants from Argentina, Brazil, Chile, and Ecuador to identify approximately 400 articles and books in Latin American social medicine. Structured abstracts were prepared, translated into English, Spanish, and Portuguese, assigned Medical Subject Headings (MeSH), and loaded into a Web-based database for public searching. The project has initiated Web-based publication for two LASM journals. Evaluation included measures of use and content. Results: The LASM Website (http://hsc.unm.edu/lasm) and database create access to formerly little-known literature that addresses problems relevant to current medicine and public health. This Website offers a unique resource for researchers, practitioners, and teachers who seek to understand the links between socioeconomic conditions and health. The project provides a model for collaboration between librarians and health care providers. Challenges included procurement of primary material; preparation of concise abstracts; working with trilingual translations of abstracts, metadata, and indexing; and the work processes of the multidisciplinary team. Conclusions: The literature of Latin American social medicine has become more readily available to researchers worldwide. The LASM project serves as a collaborative model for the creation of sustainable solutions for disseminating information that is difficult to access through traditional methods. PMID:14566372

  14. Opening the Door to the American Dream: Increasing Higher Education Access and Success for Immigrants. New York Fact Sheet

    ERIC Educational Resources Information Center

    Erisman, Wendy; Looney, Shannon

    2008-01-01

    This fact sheet presents a snapshot of important facts that are specific to the state of New York from the "Opening the Door to the American Dream: Increasing Higher Education Access and Success for Immigrants" report, which exposes systemic barriers that prevent immigrants from entering college and/or completing bachelor's degrees…

  15. Potential Impact of Increased Numbers of Physicians upon Physician Behavior, Access to, and Cost of, Medical Care. Executive Summary.

    ERIC Educational Resources Information Center

    Musgrave, Gerald L.

    A study that forecast the consequences of the projected growth in the number of practicing U.S. physicians during the 1980s and beyond is summarized. Attention was directed to the potential impact of the increasing supply of physicians on physician behavior, the cost of medical services, and access to services. Econometric modeling and analysis of…

  16. Potential Impact of Increased Numbers of Physicians upon Physician Behavior, Access to, and Cost of, Medical Care. Final Report.

    ERIC Educational Resources Information Center

    Musgrave, Gerald L.

    The potential impact of the increasing supply of physicians on physician behavior, the cost of medical services, and access to services is addressed in detail in this final research report. Econometric modeling and analyses of economic activity within the health sector were undertaken. An eight equation model of the hospital and physician sectors…

  17. Access Matters: Meeting the Nation's College Completion Goals Requires Large Increases in Need-Based Grant Aid

    ERIC Educational Resources Information Center

    Advisory Committee on Student Financial Assistance, 2013

    2013-01-01

    This document addresses the status of equality in access to higher education. Some of the motivating factors behind this presentation include: (1) College completion rates including rates of bachelor's degree completion are falling today, particularly among young Americans; (2) Reversing the current trend and increasing college completion has…

  18. Noncontingent Escape Access to Self-Reinforcement to Increase Task Engagement for Students with Moderate to Severe Disabilities

    ERIC Educational Resources Information Center

    Cihak, David F.; Gama, Robert I.

    2008-01-01

    This study determined the effectiveness of noncontingent escape access to self-reinforcement, as a student-directed intervention. Three students successfully used a break card to systematically decrease inappropriate behavior maintained by negative reinforcement while increasing task engagement. In addition, teachers completed an Intervention…

  19. Teacher Adaptations to a Core Reading Program: Increasing Access to Curriculum for Elementary Students in Urban Classrooms

    ERIC Educational Resources Information Center

    Maniates, Helen

    2017-01-01

    This article examines how three urban elementary school teachers adapted pedagogical strategies from a school district--adopted core reading program to increase their students' access to the curriculum. Using teacher interviews and classroom observations to construct a descriptive case study of teacher adaptation, analysis reveals that the…

  20. Exploring communication assistants as an option for increasing communication access to communities for people who use augmentative communication.

    PubMed

    Collier, Barbara; McGhie-Richmond, Donna; Self, Hazel

    2010-03-01

    This paper describes the results of a one-year intervention project that aimed to (a) learn about the communication supports required by people who use augmentative and alternative communication (AAC) when accessing their communities, (b) develop and implement a funded communication assistant service as an accessibility support option for people who use AAC when communicating in their communities, (c) evaluate the impact of the communication assistant service on community access for people who use AAC, and (d) make recommendations relating to the role of communication assistants as an option for increasing communication access for people who use AAC in their communities. Nine people who use AAC participated in this project. The findings suggest that the majority of participants experienced a range of communication barriers when communicating with people in their communities, and that the provision of trained communication assistants significantly increased (a) their ability to communicate and participate in their communities; (b) their feelings of dignity, empowerment, autonomy, and privacy, and (d) the quality of their community services. Unfamiliar communication partners reported increased satisfaction communicating with people who used AAC when a communication assistant was present. Implications and recommendations are made for the development of communication assistant services and further research.

  1. NASA's Astromaterials Database: Enabling Research Through Increased Access to Sample Data, Metadata and Imagery

    NASA Technical Reports Server (NTRS)

    Evans, Cindy; Todd, Nancy

    2014-01-01

    The Astromaterials Acquisition & Curation Office at NASA's Johnson Space Center (JSC) is the designated facility for curating all of NASA's extraterrestrial samples. Today, the suite of collections includes the lunar samples from the Apollo missions, cosmic dust particles falling into the Earth's atmosphere, meteorites collected in Antarctica, comet and interstellar dust particles from the Stardust mission, asteroid particles from Japan's Hayabusa mission, solar wind atoms collected during the Genesis mission, and space-exposed hardware from several missions. To support planetary science research on these samples, JSC's Astromaterials Curation Office hosts NASA's Astromaterials Curation digital repository and data access portal [http://curator.jsc.nasa.gov/], providing descriptions of the missions and collections, and critical information about each individual sample. Our office is designing and implementing several informatics initiatives to better serve the planetary research community. First, we are re-hosting the basic database framework by consolidating legacy databases for individual collections and providing a uniform access point for information (descriptions, imagery, classification) on all of our samples. Second, we continue to upgrade and host digital compendia that summarize and highlight published findings on the samples (e.g., lunar samples, meteorites from Mars). We host high resolution imagery of samples as it becomes available, including newly scanned images of historical prints from the Apollo missions. Finally we are creating plans to collect and provide new data, including 3D imagery, point cloud data, micro CT data, and external links to other data sets on selected samples. Together, these individual efforts will provide unprecedented digital access to NASA's Astromaterials, enabling preservation of the samples through more specific and targeted requests, and supporting new planetary science research and collaborations on the samples.

  2. Impact of increasing market access on a tropical small-scale fishery

    USGS Publications Warehouse

    Stevens, Kara; Irwin, Brian J.; Kramer, Daniel; Urquhart, Gerald

    2014-01-01

    Small-scale fisheries have historically been marginalized in management and policy investments, and they often remain under-reported in national economic and fisheries statistics. Even so, small-scale fisheries are not entirely buffered from the impacts of globalization, such as the introduction and expansion of markets. This study measures the long-term impact of market-access on a coastal fishery on Nicaragua׳s remote Atlantic Coast from approximately the time when fishermen had access to stable and predictable local markets until the present, when the region has been transformed by road connection. In the last four years, fisheries trade has expanded as road connection has facilitated export to distant markets. Fishery-independent surveys were used to measure changes in indicators of fish-community status such as length-frequency, mean trophic level, and relative biomass. Species-level changes in relative biomass of common snook Centropomus undecimalis and gafftopsail catfish Bagre marinus were also evaluated since these species are the most economically valuable and likely account for the most fish biomass in the system. Using historical records, reports, current observations and interviews, changes in indicators of fishing intensity and market access over the past 17 years were assessed. From 1994 to 2011, community and species-specific metrics of the lagoon fishery declined significantly across all indicators examined. The potential social and economic outcomes of the decline in the fishery are far-reaching for the region, because this tropical fishery comprises the main source of protein and income for residents of twelve indigenous and Afro-descendent communities.

  3. NASA's Astromaterials Curation Digital Repository: Enabling Research Through Increased Access to Sample Data, Metadata and Imagery

    NASA Astrophysics Data System (ADS)

    Evans, C. A.; Todd, N. S.

    2014-12-01

    The Astromaterials Acquisition & Curation Office at NASA's Johnson Space Center (JSC) is the designated facility for curating all of NASA's extraterrestrial samples. Today, the suite of collections includes the lunar samples from the Apollo missions, cosmic dust particles falling into the Earth's atmosphere, meteorites collected in Antarctica, comet and interstellar dust particles from the Stardust mission, asteroid particles from Japan's Hayabusa mission, solar wind atoms collected during the Genesis mission, and space-exposed hardware from several missions. To support planetary science research on these samples, JSC's Astromaterials Curation Office hosts NASA's Astromaterials Curation digital repository and data access portal [http://curator.jsc.nasa.gov/], providing descriptions of the missions and collections, and critical information about each individual sample. Our office is designing and implementing several informatics initiatives to better serve the planetary research community. First, we are re-hosting the basic database framework by consolidating legacy databases for individual collections and providing a uniform access point for information (descriptions, imagery, classification) on all of our samples. Second, we continue to upgrade and host digital compendia that summarize and highlight published findings on the samples (e.g., lunar samples, meteorites from Mars). We host high resolution imagery of samples as it becomes available, including newly scanned images of historical prints from the Apollo missions. Finally we are creating plans to collect and provide new data, including 3D imagery, point cloud data, micro CT data, and external links to other data sets on selected samples. Together, these individual efforts will provide unprecedented digital access to NASA's Astromaterials, enabling preservation of the samples through more specific and targeted requests, and supporting new planetary science research and collaborations on the samples.

  4. Levetiracetam results in increased and decreased alcohol drinking with different access procedures in C57BL/6J mice.

    PubMed

    Fish, Eric W; Agoglia, Abigail E; Krouse, Michael C; Muller, R Grant; Robinson, J Elliott; Malanga, C J

    2014-02-01

    The antiepileptic levetiracetam (LEV) has been investigated for the treatment of alcohol abuse. However, little is known about how LEV alters the behavioral effects of alcohol in laboratory animals. The acute effects of LEV on alcohol drinking by male C57BL/6J mice were investigated using two different drinking procedures, limited access [drinking-in-the-dark (DID)] and intermittent access (IA) drinking. In the first experiment (DID), mice had access to a single bottle containing alcohol or sucrose for 4 h every other day. In the second experiment (IA), mice had IA to two bottles, one containing alcohol or sucrose and one containing water, for 24 h on Monday, Wednesday, and Friday. In both experiments, mice were administered LEV (0.3-100 mg/kg intraperitoneally) or vehicle 30 min before access to the drinking solutions. In the DID mice, LEV increased alcohol intake from 4.3 to 5.4 g/kg, whereas in the IA mice LEV decreased alcohol intake from 4.8 to 3.0 g/kg in the first 4 h of access and decreased 24 h alcohol intake from 20 to ∼15 g/kg. These effects appear specific to alcohol, as LEV did not affect sucrose intake in either experiment. LEV appears to differentially affect drinking in animal models of moderate and heavier alcohol consumption.

  5. Estimating Contraceptive Needs and Increasing Access to Contraception in Response to the Zika Virus Disease Outbreak--Puerto Rico, 2016.

    PubMed

    Tepper, Naomi K; Goldberg, Howard I; Bernal, Manuel I Vargas; Rivera, Brenda; Frey, Meghan T; Malave, Claritsa; Renquist, Christina M; Bracero, Nabal Jose; Dominguez, Kenneth L; Sanchez, Ramon E; Shapiro-Mendoza, Carrie K; Rodriguez, Blanca R Cuevas; Simeone, Regina M; Pesik, Nicki T; Barfield, Wanda D; Ko, Jean Y; Galang, Romeo R; Perez-Padilla, Janice; Polen, Kara N D; Honein, Margaret A; Rasmussen, Sonja A; Jamieson, Denise J

    2016-04-01

    Zika virus is a flavivirus transmitted primarily by Aedes species mosquitoes. Increasing evidence links Zika virus infection during pregnancy to adverse pregnancy and birth outcomes, including pregnancy loss, intrauterine growth restriction, eye defects, congenital brain abnormalities, and other fetal abnormalities. The virus has also been determined to be sexually transmitted. Because of the potential risks associated with Zika virus infection during pregnancy, CDC has recommended that health care providers discuss prevention of unintended pregnancy with women and couples who reside in areas of active Zika virus transmission and do not want to become pregnant. However, limitations in access to contraception in some of these areas might affect the ability to prevent an unintended pregnancy. As of March 16, 2016, the highest number of Zika virus disease cases in the United States and U.S. territories were reported from Puerto Rico. The number of cases will likely rise with increasing mosquito activity in affected areas, resulting in increased risk for transmission to pregnant women. High rates of unintended and adolescent pregnancies in Puerto Rico suggest that, in the context of this outbreak, access to contraception might need to be improved. CDC estimates that 138,000 women of reproductive age (aged 15-44 years) in Puerto Rico do not desire pregnancy and are not using one of the most effective or moderately effective contraceptive methods, and therefore might experience an unintended pregnancy. CDC and other federal and local partners are seeking to expand access to contraception for these persons. Such efforts have the potential to increase contraceptive access and use, reduce unintended pregnancies, and lead to fewer adverse pregnancy and birth outcomes associated with Zika virus infection during pregnancy. The assessment of challenges and resources related to contraceptive access in Puerto Rico might be a useful model for other areas with active transmission

  6. Increasing Access to Atmospheric Science Research at NASA Langley Research Center

    NASA Astrophysics Data System (ADS)

    Chambers, L. H.; Bethea, K. L.; LaPan, J. C.

    2013-12-01

    The Science Directorate (SD) at NASA's Langley Research Center conducts cutting edge research in fundamental atmospheric science topics including radiation and climate, air quality, active remote sensing, and upper atmospheric composition. These topics matter to the public, as they improve our understanding of our home planet. Thus, we have had ongoing efforts to improve public access to the results of our research. These efforts have accelerated with the release of the February OSTP memo. Our efforts can be grouped in two main categories: 1. Visual presentation techniques to improve science understanding: For fundamental concepts such as the Earth's energy budget, we have worked to display information in a more "digestible" way for lay audiences with more pictures and fewer words. These audiences are iPad-lovers and TV-watchers with shorter attention spans than audiences of the past. They are also educators and students who need a basic understanding of a concept delivered briefly to fit into busy classroom schedules. We seek to reach them with a quick, visual message packed with important information. This presentation will share several examples of visual techniques, such as infographics (e.g., a history of lidar at Langley and a timeline of atmospheric research, ozone garden diagrams (http://science-edu.larc.nasa.gov/ozonegarden/ozone-cycle.php); history of lidar at LaRC; DISCOVER-AQ maps. It will also share examples of animations and interactive graphics (DISCOVER-AQ); and customized presentations (e.g., to explain the energy budget or to give a general overview of research). One of the challenges we face is a required culture shift between the way scientists traditionally share knowledge with each other and the way these public audiences ingest knowledge. A cross-disciplinary communications team in SD is crucial to bridge that gap. 2. Lay research summaries to make research more accessible: Peer-reviewed publications are a primary product of the SD, with more

  7. Fifty Years of Family Planning: New Evidence on the Long-Run Effects of Increasing Access to Contraception

    PubMed Central

    Bailey, Martha J.

    2014-01-01

    This paper assembles new evidence on some of the longer-term consequences of U.S. family planning policies, defined in this paper as those increasing legal or financial access to modern contraceptives. The analysis leverages two large policy changes that occurred during the 1960s and 1970s: first, the interaction of the birth control pill’s introduction with Comstock-era restrictions on the sale of contraceptives and the repeal of these laws after Griswold v. Connecticut in 1965; and second, the expansion of federal funding for local family planning programs from 1964 to 1973. Building on previous research that demonstrates both policies’ effects on fertility rates, I find suggestive evidence that individuals’ access to contraceptives increased their children’s college completion, labor force participation, wages, and family incomes decades later. PMID:25339778

  8. Oncofertility Program Implementation Increases Access to Fertility Preservation Options and Assisted Reproductive Procedures for Breast Cancer Patients

    PubMed Central

    VU, JOCELINE V.; LLARENA, NATALIA C.; ESTEVEZ, SAMANTHA L.; MORAVEK, MOLLY B.; JERUSS, JACQUELINE S.

    2017-01-01

    Background and Objectives Breast cancer treatment can cause premature ovarian failure, yet the majority of young cancer patients do not receive adequate education about treatment effects before initiating chemotherapy. We studied the impact of an oncofertility program on access to fertility preservation. Methods An oncofertility program was initiated to foster collaboration between oncologists and reproductive endocrinologists, and to help increase access to fertility preservation. Documented conversations about fertility concerns, specialist referrals, appointments, and fertility preservation procedures were compared between breast cancer patients from 2004 to 2006, before oncofertility program initiation, and 2007–2012, after program initiation. The study included women <45, stages 0–III, diagnosed before (n =278) and after (n =515) program initiation. Results Demographics for the cohorts were similar. Fertility discussions (P <0.0001), patients interested in maintaining fertility at diagnosis (P =0.0041), referrals to reproductive endocrinologists (P <0.0001), appointments (P <0.0001), and fertility preservation procedures (P <0.0183) increased significantly after programmatic implementation. Conclusions An oncofertility program increased discussions about fertility preservation and access to assisted reproductive procedures. This program positively impacted compliance with national guidelines advising reproductive-age cancer patients to be offered fertility preservation counseling as an initial component of the multidisciplinary care plan. PMID:27966219

  9. Optimal dynamic bandwidth allocation for complex networks

    NASA Astrophysics Data System (ADS)

    Jiang, Zhong-Yuan; Liang, Man-Gui; Li, Qian; Guo, Dong-Chao

    2013-03-01

    Traffic capacity of one network strongly depends on the link’s bandwidth allocation strategy. In previous bandwidth allocation mechanisms, once one link’s bandwidth is allocated, it will be fixed throughout the overall traffic transmission process. However, the traffic load of every link changes from time to time. In this paper, with finite total bandwidth resource of the network, we propose to dynamically allocate the total bandwidth resource in which each link’s bandwidth is proportional to the queue length of the output buffer of the link per time step. With plenty of data packets in the network, the traffic handling ability of all links of the network achieves full utilization. The theoretical analysis and the extensive simulation results on complex networks are consistent. This work is valuable for network service providers to improve network performance or to do reasonable network design efficiently.

  10. Increasing Accessibility: Lessons Learned in Retaining Special Population Students in Canada

    ERIC Educational Resources Information Center

    Smith, Clayton; Gottheil, Susan

    2011-01-01

    In Canada, changing demographics and increased competition--as well as social values based on equity--have inspired efforts to increase the postsecondary education (PSE) participation rates of youths from under-represented/under-served groups. Despite its population having the highest level of educational attainment among those of OECD countries,…

  11. Effective Communication and File-I/O Bandwidth Benchmarks

    SciTech Connect

    Koniges, A E; Rabenseifner, R

    2001-05-02

    We describe the design and MPI implementation of two benchmarks created to characterize the balanced system performance of high-performance clusters and supercomputers: b{_}eff, the communication-specific benchmark examines the parallel message passing performance of a system, and b{_}eff{_}io, which characterizes the effective 1/0 bandwidth. Both benchmarks have two goals: (a) to get a detailed insight into the Performance strengths and weaknesses of different parallel communication and I/O patterns, and based on this, (b) to obtain a single bandwidth number that characterizes the average performance of the system namely communication and 1/0 bandwidth. Both benchmarks use a time driven approach and loop over a variety of communication and access patterns to characterize a system in an automated fashion. Results of the two benchmarks are given for several systems including IBM SPs, Cray T3E, NEC SX-5, and Hitachi SR 8000. After a redesign of b{_}eff{_}io, I/O bandwidth results for several compute partition sizes are achieved in an appropriate time for rapid benchmarking.

  12. Bandwidth controller for phase-locked-loop

    NASA Technical Reports Server (NTRS)

    Brockman, Milton H. (Inventor)

    1992-01-01

    A phase locked loop utilizing digital techniques to control the closed loop bandwidth of the RF carrier phase locked loop in a receiver provides high sensitivity and a wide dynamic range for signal reception. After analog to digital conversion, a digital phase locked loop bandwidth controller provides phase error detection with automatic RF carrier closed loop tracking bandwidth control to accommodate several modes of transmission.

  13. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Emission bandwidth. 95.633 Section 95.633... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. Link to an amendment... transmission) for emission type H1D, J1D, R1D, H3E, J3E or R3E is 4 kHz. The authorized bandwidth for...

  14. Paired comparisons of nonlinear frequency compression, extended bandwidth, and restricted bandwidth hearing-aid processing for children and adults with hearing loss

    PubMed Central

    Brennan, Marc A.; McCreery, Ryan; Kopun, Judy; Hoover, Brenda; Alexander, Joshua; Lewis, Dawna; Stelmachowicz, Patricia G.

    2014-01-01

    Background Preference for speech and music processed with nonlinear frequency compression and two controls (restricted and extended bandwidth hearing-aid processing) was examined in adults and children with hearing loss. Purpose Determine if stimulus type (music, sentences), age (children, adults) and degree of hearing loss influence listener preference for nonlinear frequency compression, restricted bandwidth and extended bandwidth. Research Design Within-subject, quasi-experimental study. Using a round-robin procedure, participants listened to amplified stimuli that were 1) frequency-lowered using nonlinear frequency compression, 2) low-pass filtered at 5 kHz to simulate the restricted bandwidth of conventional hearing aid processing, or 3) low-pass filtered at 11 kHz to simulate extended bandwidth amplification. The examiner and participants were blinded to the type of processing. Using a two-alternative forced-choice task, participants selected the preferred music or sentence passage. Study Sample Sixteen children (8–16 years) and 16 adults (19–65 years) with mild-to-severe sensorineural hearing loss. Intervention All subjects listened to speech and music processed using a hearing-aid simulator fit to the Desired Sensation Level algorithm v.5.0a (Scollie et al, 2005). Results Children and adults did not differ in their preferences. For speech, participants preferred extended bandwidth to both nonlinear frequency compression and restricted bandwidth. Participants also preferred nonlinear frequency compression to restricted bandwidth. Preference was not related to degree of hearing loss. For music, listeners did not show a preference. However, participants with greater hearing loss preferred nonlinear frequency compression to restricted bandwidth more than participants with less hearing loss. Conversely, participants with greater hearing loss were less likely to prefer extended bandwidth to restricted bandwidth. Conclusion Both age groups preferred access to

  15. Utilizing Task Shifting to Increase Access to Maternal and Infant Health Interventions: A Case Study of Midwives for Haiti.

    PubMed

    Floyd, Barbara O'Malley; Brunk, Nadene

    2016-01-01

    The shortage of health workers worldwide has been identified as a barrier to achieving targeted health goals. Task shifting has been recommended by the World Health Organization to increase access to trained and skilled birth attendants. One example of task shifting is the use of cadres of health care workers, such as nurses and auxiliary nurse-midwives, who can successfully deliver skilled care to women and infants in low-resource areas where women would otherwise lack access to critical health interventions during the childbearing years. Midwives for Haiti is an organization demonstrating the use of task shifting in its education program for auxiliary midwives. Graduates of the Midwives for Haiti education program are employed and working with women in hospitals, birth centers, and clinics across Haiti. This article reviews the Midwives for Haiti education program and presents successes and challenges in task shifting as a strategy to increase access to skilled maternal and newborn care and to meet international health goals to reduce maternal and infant mortality in a low-resource country.

  16. Increasing Access to Medical Education for Students from Medically Underserved Communities: One Program's Success.

    ERIC Educational Resources Information Center

    Thompson, William A.; Ferry, Pamela G.; King, Jason E.; Martinez-Wedig, Cindy; Michael, Lloyd H.

    2003-01-01

    Describes the Premedical Honors College (PHC), an eight-year, BS-MD program created by Baylor College of Medicine and the University of Texas-Pan American to increase the number of physicians addressing underserved populations in Texas. An outcomes study comparing PHC matriculants with students of similar academic ability, ethnicity, and interest…

  17. An Increase in Mean Platelet Volume/Platelet Count Ratio Is Associated with Vascular Access Failure in Hemodialysis Patients

    PubMed Central

    Shin, Dong Ho; Rhee, So Yon; Jeon, Hee Jung; Park, Ji-Young; Kang, Shin-Wook; Oh, Jieun

    2017-01-01

    After stenosis of arteriovenous vascular access in hemodialysis patients, platelets play a crucial role in subsequent thrombus formation, leading to access failure. In a previous study, the mean platelet volume (MPV)/platelet count ratio, but not MPV alone, was shown to be an independent predictor of 4-year mortality after myocardial infarction. However, little is known about the potential influence of MPV/platelet count ratio on vascular access patency in hemodialysis patients. A total of 143 patients undergoing routine hemodialysis were recruited between January 2013 and February 2016. Vascular access failure (VAF) was defined as thrombosis or a decrease of greater than 50% of normal vessel diameter, requiring either surgical revision or percutaneous transluminal angioplasty. Cox proportional hazards model analysis ascertained that the change of MPV/platelet count ratio between baseline and 3 months [Δ(MPV/platelet count ratio)3mo-baseline] had prognostic value for VAF. Additionally, the changes of MPV/platelet count ratio over time were compared in patients with and without VAF by using linear mixed model analysis. Of the 143 patients, 38 (26.6%) were diagnosed with VAF. During a median follow-up of 26.9 months (interquartile range 13.0–36.0 months), Δ(MPV/platelet count ratio)3mo-baseline significantly increased in patients with VAF compared to that in patients without VAF [11.6 (6.3–19.0) vs. 0.8 (-1.8–4.0), P< 0.001]. In multivariate analysis, Δ(MPV/platelet ratio count)3mo-baseline was an independent predictor of VAF, after adjusting for age, sex, diabetes, hypertension, coronary artery disease, cerebrovascular disease, vascular access type, the presence of previous VAF, and antiplatelet drug use (hazard ratio, 1.15; 95% confidence interval, 1.10–1.21; P< 0.001). Moreover, a liner mixed model revealed that there was a significant increase of MPV/platelet count ratio over time in patients with VAF compared to those without VAF (P< 0.001). An

  18. WE-AB-204-03: Increasing Access to Medical Physics Education and Research Excellence (AMPERE).

    PubMed

    Ngwa, W

    2016-06-01

    Many efforts have been made to increase diversity in the science workforce. In order for us to be competitive in innovation and ingenuity we need to reach out to any source of intellectual talent. Having greater diversity can only increase the creativity in medical physics. In order for students to succeed academically they need role models and mentors with whom they can identify. Literature has shown that racial and ethnic diversity has both direct and indirect positive effects on the educational outcomes, career advancement and motivation of students. Diversity not only focuses on race, ethnicity and gender, but it can also include socioeconomic status, sexual orientation and more. Underrepresented populations have had low numbers over the years not only in medical physics but also in the sciences in general. With the rapidly changing face of our country we need to address how we attract and train the next generation of scientists to stay competitive. It is necessary to examine the role that diversity and inclusion play in the long term goals of institutions, workplaces and classrooms. To increase innovation we must engage people from all walks of life with different perspectives and life experiences to solve the problems that we will face. Diversity should be viewed as a strategy to achieve our goals instead of acts of good citizenship. Many of today's businesses and corporations have discovered that embracing diversity prepares future leaders in today's global market. This lecture will provide insight to how differences within our society can drive innovation. We will provide an overview of the role diversity and inclusion plays in the clinic, education and research to develop the future workforce in medical physics.

  19. A meta-substrate to enhance the bandwidth of metamaterials

    PubMed Central

    Chen, Hongsheng; Wang, Zuojia; Zhang, Runren; Wang, Huaping; Lin, Shisheng; Yu, Faxin; Moser, Herbert O.

    2014-01-01

    We propose the concept of a meta-substrate to broaden the bandwidth of left-handed metamaterials. The meta-substrate, which behaves like an inhomogeneous magnetic substrate, is composed of another kind of magnetic metamaterials like metallic closed rings. When conventional metamaterial rings are printed on this kind of meta-substrate in a proper way, the interaction of the metamaterials units can be greatly enhanced, yielding an increased bandwidth of negative permeability. An equivalent circuit analytical model is used to quantitatively characterize this phenomenon. Both numerical and experimental demonstrations are carried out, showing good agreement with theoretical predictions. PMID:24919678

  20. Bandwidth and threshold calculations for angle-tuned parametric oscillators.

    NASA Technical Reports Server (NTRS)

    Basu, R.; Steier, W. H.

    1972-01-01

    The bandwidth of angle-tuned optical parametric oscillators, in some cases, is limited by the noncolinear interaction of the pump, signal, and idler beams, which results when the nonlinear material is rotated relative to the pump beam. To determine this bandwidth, a theoretical expression for the pump power threshold is derived in the near field limit taking into account double refraction for a noncolinear interaction. Angle tuning can be done by (1) rotating the crystal and mirrors as a unit, or by (2) rotating the crystal only. Expressions for determining the tuning rate and threshold increase for both tuning methods are derived.

  1. New cardiac surgery programs established from 1993 to 2004 led to little increased access, substantial duplication of services.

    PubMed

    Lucas, Frances Leslie; Siewers, Andrea; Goodman, David C; Wang, Dongmei; Wennberg, David E

    2011-08-01

    Despite decreasing demand for bypass surgery, 301 new cardiac surgery programs opened between 1993 and 2004. We used Medicare data to identify where the new programs opened and to assess their impact on access and efficiency. Forty-two percent of the new programs opened in communities that already had access to cardiac surgery, which suggests that their creation has led to a fight for shares of a shrinking market. New programs were much more likely to open in states that did not require them to show a certificate-of-need. Overall, travel time to the nearest cardiac surgery program changed little, which suggests that these programs have done little to improve geographic access. The duplication of services that resulted in many areas may have engendered competition based on quality, price, or both, but it may also have increased surgical rates, with unknown results. We observe that certificate-of-need requirements may help avoid unnecessary duplication of services by preventing new programs from opening in close proximity to existing ones.

  2. Bandwidth enhancement of dielectric resonator antennas

    NASA Technical Reports Server (NTRS)

    Lee, Richard Q.; Simons, Rainee N.

    1993-01-01

    An experimental investigation of bandwidth enhancement of dielectric resonator antennas (DRA) using parasitic elements is reported. Substantial bandwidth enhancement for the HE(sub 11delta) mode of the stacked geometry and for the HE(sub 13delta) mode of the coplanar collinear geometry was demonstrated. Excellent radiation patterns for the HE(sub 11delta) mode were also recorded.

  3. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. (a) Each authorization issued pursuant to these...

  4. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. Link to an amendment published at 77 FR 54432, Sept....

  5. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. (a) Each authorization issued pursuant to these...

  6. Energy Bandwidth for Petroleum Refining Processes

    SciTech Connect

    none,

    2006-10-01

    The petroleum refining energy bandwidth report analyzes the most energy-intensive unit operations used in U.S. refineries: crude oil distillation, fluid catalytic cracking, catalytic hydrotreating, catalytic reforming, and alkylation. The "bandwidth" provides a snapshot of the energy losses that can potentially be recovered through best practices and technology R&D.

  7. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. (a) Each authorization issued pursuant to these...

  8. 47 CFR 101.109 - Bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth. 101.109 Section 101.109 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Technical Standards § 101.109 Bandwidth. Link to an amendment published at 76 FR 59572, Sept....

  9. 47 CFR 90.209 - Bandwidth limitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth limitations. 90.209 Section 90.209 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES General Technical Standards § 90.209 Bandwidth limitations. (a) Each...

  10. 47 CFR 90.209 - Bandwidth limitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth limitations. 90.209 Section 90.209 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES General Technical Standards § 90.209 Bandwidth limitations. (a) Each...

  11. 47 CFR 90.209 - Bandwidth limitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bandwidth limitations. 90.209 Section 90.209 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES General Technical Standards § 90.209 Bandwidth limitations. (a) Each...

  12. 47 CFR 90.209 - Bandwidth limitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bandwidth limitations. 90.209 Section 90.209 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND MOBILE RADIO SERVICES General Technical Standards § 90.209 Bandwidth limitations. (a) Each...

  13. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... quality desired Speech and music, M=4000, Bandwidth: 8000 Hz= 8 kHz 8K00A3E Sound broadcasting, single... desired Speech and music, M=4000, Bandwidth: 4000 Hz= 4 kHz 4K00R3E Sound broadcasting, single-sideband, suppressed carrier Bn=M−lowest modulation frequency Speech and music, M=4500, lowest modulation...

  14. 47 CFR 95.633 - Emission bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES Technical Regulations Technical Standards § 95.633 Emission bandwidth. (a) The authorized... frequencies 151.820 MHz, 151.880 MHz, and 151.940 MHz are limited to 11.25 kHz. (2) Emissions on frequencies... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emission bandwidth. 95.633 Section...

  15. A hybrid OFDM-TDM architecture with decentralized dynamic bandwidth allocation for PONs.

    PubMed

    Cevik, Taner

    2013-01-01

    One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand.

  16. A Hybrid OFDM-TDM Architecture with Decentralized Dynamic Bandwidth Allocation for PONs

    PubMed Central

    Cevik, Taner

    2013-01-01

    One of the major challenges of passive optical networks is to achieve a fair arbitration mechanism that will prevent possible collisions from occurring at the upstream channel when multiple users attempt to access the common fiber at the same time. Therefore, in this study we mainly focus on fair bandwidth allocation among users, and present a hybrid Orthogonal Frequency Division Multiplexed/Time Division Multiplexed architecture with a dynamic bandwidth allocation scheme that provides satisfying service qualities to the users depending on their varying bandwidth requirements. Unnecessary delays in centralized schemes occurring during bandwidth assignment stage are eliminated by utilizing a decentralized approach. Instead of sending bandwidth demands to the optical line terminal (OLT) which is the only competent authority, each optical network unit (ONU) runs the same bandwidth demand determination algorithm. ONUs inform each other via signaling channel about the status of their queues. This information is fed to the bandwidth determination algorithm which is run by each ONU in a distributed manner. Furthermore, Light Load Penalty, which is a phenomenon in optical communications, is mitigated by limiting the amount of bandwidth that an ONU can demand. PMID:24194684

  17. Bandwidth utilization maximization of scientific RF communication systems

    SciTech Connect

    Rey, D.; Ryan, W.; Ross, M.

    1997-01-01

    A method for more efficiently utilizing the frequency bandwidth allocated for data transmission is presented. Current space and range communication systems use modulation and coding schemes that transmit 0.5 to 1.0 bits per second per Hertz of radio frequency bandwidth. The goal in this LDRD project is to increase the bandwidth utilization by employing advanced digital communications techniques. This is done with little or no increase in the transmit power which is usually very limited on airborne systems. Teaming with New Mexico State University, an implementation of trellis coded modulation (TCM), a coding and modulation scheme pioneered by Ungerboeck, was developed for this application and simulated on a computer. TCM provides a means for reliably transmitting data while simultaneously increasing bandwidth efficiency. The penalty is increased receiver complexity. In particular, the trellis decoder requires high-speed, application-specific digital signal processing (DSP) chips. A system solution based on the QualComm Viterbi decoder and the Graychip DSP receiver chips is presented.

  18. Phagosomal degradation increases TLR access to bacterial ligands and enhances macrophage sensitivity to bacteria

    PubMed Central

    Wolf, Andrea J.; Arruda, Andrea; Reyes, Christopher N.; Kaplan, Amber T.; Shimada, Takahiro; Shimada, Kenichi; Arditi, Moshe; Liu, George; Underhill, David M.

    2011-01-01

    Signaling by innate immune receptors initiates and orchestrates the overall immune responses to infection. Macrophage receptors recognizing pathogens can be broadly grouped into surface receptors and receptors restricted to intracellular compartments, such as phagosomes and the cytoplasm. There is an expectation that ingestion and degradation of microorganisms by phagocytes contributes to activation of intracellular innate receptors, although direct demonstrations of this are rare and many model ligands are studied in soluble form, outside of their microbial context. By comparing a wild-type strain of Staphylococcus aureus and a lysozyme-sensitive mutant, we have been able to directly address the role of degradation of live bacteria by mouse macrophages in determining the overall innate cellular inflammatory response. Our investigations revealed a biphasic response to S. aureus that consisted of an initial signal resulting from the engagement of surface TLR2, followed by a later, second wave on inflammatory gene induction. This second wave of inflammatory signaling was dependent on and correlated with the timing of bacterial degradation in phagosomes. We found that TLR2 signaling followed by TLR2/TLR9 signaling enhanced sensitivity to small numbers of bacteria. We further found that treating wild-type bacteria with the peptidoglycan synthesis-inhibiting antibiotic vancomycin made S. aureus more susceptible to degradation and resulted in increased inflammatory responses, similar to those observed for mutant degradation-sensitive bacteria. PMID:22031762

  19. Increased Prevalence of Diabetes in Argentina Is Due to Easier Health Care Access Rather than to an Actual Increase in Prevalence

    PubMed Central

    Rubinstein, Adolfo; Gutierrez, Laura; Beratarrechea, Andrea; Irazola, Vilma E.

    2014-01-01

    Introduction According to the Argentine National Risk Factor Survey (ANRFS), between 2005 and 2009, self-reported Diabetes increased in Argentina from 8.4% to 9.6%, accompanied by a raise in the prevalence of obesity and low physical activity. In the same period, it also increased blood sugar checks from 69.3% to 75.7%. Since surveillance data in Argentina rely on self-reports, the estimated prevalence of diabetes may be affected by an increase in the proportion of subjects with access to preventive services. We evaluated the independent effect of a recent blood sugar check, on the increase in self-reported diagnoses of diabetes between 2005 and 2009. Materials and Methods A secondary analysis of data from the 2005 and 2009 ANRFS was performed. Diabetes was defined as having been diagnosed Diabetes or high blood sugar by a health professional, obesity was calculated as BMI≥30 kg/m2, based on self-reported height and weight and physical activity was measured using the International Physical Activity Questionnaire. We used logistic regression models to explore the relationship between prevalence of self-reported diabetes and recent blood sugar check as the main predictor. Results The prevalence of diabetes rose from 8.4% to 9.6%; obesity from 14.5% to 18% and low physical activity from 46.2% to 55%, between 2005 and 2009. Among those who recently checked their blood sugar no differences were found in the prevalence of diabetes: 13% in 2005 vs. 13.2% in 2009. Findings of the multivariable analysis showed that obesity and low physical activity were significantly associated with self reported diabetes in the adjusted model (OR = 1.80 for obesity, and OR = 1.12 for low physical activity but the strongest predictor was recent blood sugar check (OR = 4.75). Discussion An increased prevalence of self-reported diabetes between 2005 and 2009 might indicate an improvement in the access to preventive services rather than a positive increase in the prevalence of

  20. Hindlimb heating increases vascular access of large molecules to murine tibial growth plates measured by in vivo multiphoton imaging.

    PubMed

    Serrat, Maria A; Efaw, Morgan L; Williams, Rebecca M

    2014-02-15

    Advances in understanding the molecular regulation of longitudinal growth have led to development of novel drug therapies for growth plate disorders. Despite progress, a major unmet challenge is delivering therapeutic agents to avascular-cartilage plates. Dense extracellular matrix and lack of penetrating blood vessels create a semipermeable "barrier," which hinders molecular transport at the vascular-cartilage interface. To overcome this obstacle, we used a hindlimb heating model to manipulate bone circulation in 5-wk-old female mice (n = 22). Temperatures represented a physiological range of normal human knee joints. We used in vivo multiphoton microscopy to quantify temperature-enhanced delivery of large molecules into tibial growth plates. We tested the hypothesis that increasing hindlimb temperature from 22°C to 34°C increases vascular access of large systemic molecules, modeled using 10, 40, and 70 kDa dextrans that approximate sizes of physiological regulators. Vascular access was quantified by vessel diameter, velocity, and dextran leakage from subperichondrial plexus vessels and accumulation in growth plate cartilage. Growth plate entry of 10 kDa dextrans increased >150% at 34°C. Entry of 40 and 70 kDa dextrans increased <50%, suggesting a size-dependent temperature enhancement. Total dextran levels in the plexus increased at 34°C, but relative leakage out of vessels was not temperature dependent. Blood velocity and vessel diameter increased 118% and 31%, respectively, at 34°C. These results demonstrate that heat enhances vascular carrying capacity and bioavailability of large molecules around growth plates, suggesting that temperature could be a noninvasive strategy for modulating delivery of therapeutics to impaired growth plates of children.

  1. "La Comunidad Habla": Using Internet Community-Based Information Interventions to Increase Empowerment and Access to Health Care of Low Income Latino/a Immigrants

    ERIC Educational Resources Information Center

    Ginossar, Tamar; Nelson, Sara

    2010-01-01

    The innovative educational communication interventions described in this paper include the use of bi-lingual, low literacy level websites and training created by low income Latina women to increase access to health care, health information, and the internet. We focus on one grassroots intervention, aimed at increasing access to health care for…

  2. Is the prevalence of youth smoking affected by efforts to increase retailer compliance with a minors' access law?

    PubMed

    Cummings, K Michael; Hyland, Andrew; Perla, Jeanne; Giovino, Gary A

    2003-08-01

    This study correlated measures of youth smoking behavior with community-level indicators of retailer compliance with a minors' tobacco access law. The study was carried out between 1992 and 1996 in 12 communities in Erie County, New York. Retailer compliance was assessed by having adolescents attempt to purchase tobacco products in licensed tobacco-selling outlets in fall 1994 and fall 1995 after implementation of an aggressive enforcement program. Communities were grouped in two ways: (a) those that did or did not increase retailer compliance rates by 200% or more between 1994 and 1995 and (b) those that did or did not achieve an 80% retailer compliance rate in 1995. School-based surveys conducted in 1992 and 1996 assessed the tobacco use behaviors of ninth-grade public school students. Between 1994 and 1995, retailer compliance increased in all 12 communities by an average of 155%. In 1995, six of the 12 communities achieved retailer compliance rates in excess of 80%. Indicators of youth smoking behavior did not vary significantly between communities that increased their retailer compliance rates by more or less than 200%. The prevalence of past 30-day smoking remained stable between 1992 and 1996 in the six communities that achieved a retailer compliance rate of at least 80% and increased slightly in the remaining communities. The prevalence of frequent smoking decreased between 1992 and 1996 in the communities that achieved a retailer compliance rate of at least 80% and increased slightly in the six communities that failed to achieve this rate. Achieving a high rate of retailer compliance with a minors' access law appears to have caused youths to rely more on noncommercial sources of cigarettes and may have had a small effect on adolescent smoking prevalence, especially frequent smoking.

  3. Does Health Insurance Premium Exemption Policy for Older People Increase Access to Health Care? Evidence from Ghana.

    PubMed

    Duku, Stephen Kwasi Opuku; van Dullemen, Caroline Elisabeth; Fenenga, Christine

    2015-01-01

    Aging in Sub-Saharan Africa causes major challenges for policy makers in social protection. Our study focuses on Ghana, one of the few Sub-Saharan African countries that passed a National Policy on Aging in 2010. Ghana is also one of the first Sub-Saharan African countries that launched a National Health Insurance Scheme (NHIS; NHIS Act 650, 2003) with the aim to improve access to quality health care for all citizens, and as such can be considered as a means of poverty reduction. Our study assesses whether premium exemption policy under the NHIS that grants non-payments of annual health insurance premiums for older people increases access to health care. We assessed differences in enrollment coverage among four different age groups (18-49, 50-59, 60-69, and 70+). We found higher enrollment for the 70+ and 60-69 age groups. The likelihood of enrollment was 2.7 and 1.7 times higher for the 70+ and 60-69 age groups, respectively. Our results suggest the NHIS exemption policy increases insurance coverage of the aged and their utilization of health care services.

  4. Increase of TCR V beta accessibility within E beta regulatory region influences its recombination frequency but not allelic exclusion.

    PubMed

    Senoo, Makoto; Wang, Lili; Suzuki, Daisuke; Takeda, Naoki; Shinkai, Yoichi; Habu, Sonoko

    2003-07-15

    Seventy percent of the murine TCRbeta locus (475 kb) was deleted to generate a large deleted TCRbeta (beta(LD)) allele to investigate a possible linkage between germline transcription, recombination frequency, and allelic exclusion of the TCR Vbeta genes. In these beta(LD/LD) mice, the TCRbeta gene locus contained only four Vbeta genes at the 5' side of the locus, and consequently, the Vbeta10 gene was located in the original Dbeta1-Jbeta1cluster within the Ebeta regulatory region. We showed that the frequency of recombination and expression of the Vbeta genes are strongly biased to Vbeta10 in these mutant mice even though the proximity of the other three 5'Vbeta genes was also greatly shortened toward the Dbeta-Jbeta cluster and the Ebeta enhancer. Accordingly, the germline transcription of the Vbeta10 gene in beta(LD/LD) mice was exceptionally enhanced in immature double negative thymocytes compared with that in wild-type mice. During double negative-to-double positive transition of thymocytes, the level of Vbeta10 germline transcription was prominently increased in beta(LD/LD) recombination activating gene 2-deficient mice receiving anti-CD3epsilon Ab in vivo. Interestingly, however, despite the increased accessibility of the Vbeta10 gene in terms of transcription, allelic exclusion of this Vbeta gene was strictly maintained in beta(LD/LD) mice. These results provide strong evidence that increase of Vbeta accessibility influences frequency but not allelic exclusion of the TCR Vbeta rearrangement if the Vbeta gene is located in the Ebeta regulatory region.

  5. The surface accessibility of the glycine receptor M2-M3 loop is increased in the channel open state.

    PubMed

    Lynch, J W; Han, N L; Haddrill, J; Pierce, K D; Schofield, P R

    2001-04-15

    Mutations in the extracellular M2-M3 loop of the glycine receptor (GlyR) alpha1 subunit have been shown previously to affect channel gating. In this study, the substituted cysteine accessibility method was used to investigate whether a structural rearrangement of the M2-M3 loop accompanies GlyR activation. All residues from R271C to V277C were covalently modified by both positively charged methanethiosulfonate ethyltrimethylammonium (MTSET) and negatively charged methanethiosulfonate ethylsulfonate (MTSES), implying that these residues form an irregular surface loop. The MTSET modification rate of all residues from R271C to K276C was faster in the glycine-bound state than in the unliganded state. MTSES modification of A272C, L274C, and V277C was also faster in the glycine-bound state. These results demonstrate that the surface accessibility of the M2-M3 loop is increased as the channel transitions from the closed to the open state, implying that either the loop itself or an overlying domain moves during channel activation.

  6. Closing the digital divide in HIV/AIDS care: development of a theory-based intervention to increase Internet access.

    PubMed

    Kalichman, S C; Weinhardt, L; Benotsch, E; Cherry, C

    2002-08-01

    Advances in information technology are revolutionizing medical patient education and the Internet is becoming a major source of information for people with chronic medical conditions, including HIV/AIDS. However, many AIDS patients do not have equal access to the Internet and are therefore at an information disadvantage, particularly minorities, persons of low-income levels and individuals with limited education. This paper describes the development and pilot testing of a workshop-style intervention designed to close the digital divide in AIDS care. Grounded in the Information-Motivation-Behavioral Skills (IMB) model of health behaviour change, we developed an intervention for persons with no prior history of using the Internet. The intervention included instruction in using hardware and search engines, motivational enhancement to increase interest and perceived relevance of the Internet, and skills for critically evaluating and using health information accessed via the Internet. Participants were also introduced to communication and support functions of the Internet including e-mail, newsgroups and chat groups. Pilot testing demonstrated feasibility, acceptability and promise for closing the digital divide in HIV/AIDS care using a relatively brief and intensive theory-based intervention that could be implemented in community settings.

  7. Increasing Equity and Compensating Historically Academically Disadvantaged Students at a Tertiary Level: Benefits of a Science Foundation Programme as a Way of Access

    ERIC Educational Resources Information Center

    Downs, Colleen

    2010-01-01

    An approach to remedy the scarcity of Black students within the sciences at southern African universities has been the development of access programmes. There has been little acknowledgement of the contribution of these access programmes in increasing the quantity and quality of graduates. The contribution made by the Science Foundation Programme…

  8. WDM package enabling high-bandwidth optical intrasystem interconnects for high-performance computer systems

    NASA Astrophysics Data System (ADS)

    Schrage, J.; Soenmez, Y.; Happel, T.; Gubler, U.; Lukowicz, P.; Mrozynski, G.

    2006-02-01

    From long haul, metro access and intersystem links the trend goes to applying optical interconnection technology at increasingly shorter distances. Intrasystem interconnects such as data busses between microprocessors and memory blocks are still based on copper interconnects today. This causes a bottleneck in computer systems since the achievable bandwidth of electrical interconnects is limited through the underlying physical properties. Approaches to solve this problem by embedding optical multimode polymer waveguides into the board (electro-optical circuit board technology, EOCB) have been reported earlier. The principle feasibility of optical interconnection technology in chip-to-chip applications has been validated in a number of projects. For reasons of cost considerations waveguides with large cross sections are used in order to relax alignment requirements and to allow automatic placement and assembly without any active alignment of components necessary. On the other hand the bandwidth of these highly multimodal waveguides is restricted due to mode dispersion. The advance of WDM technology towards intrasystem applications will provide sufficiently high bandwidth which is required for future high-performance computer systems: Assuming that, for example, 8 wavelength-channels with 12Gbps (SDR1) each are given, then optical on-board interconnects with data rates a magnitude higher than the data rates of electrical interconnects for distances typically found at today's computer boards and backplanes can be realized. The data rate will be twice as much, if DDR2 technology is considered towards the optical signals as well. In this paper we discuss an approach for a hybrid integrated optoelectronic WDM package which might enable the application of WDM technology to EOCB.

  9. Long-term outcomes of a dental postbaccalaureate program: increasing dental student diversity and oral health care access.

    PubMed

    Wides, Cynthia D; Brody, Harvey A; Alexander, Charles J; Gansky, Stuart A; Mertz, Elizabeth A

    2013-05-01

    The University of California, San Francisco School of Dentistry established the Dental Postbaccalaureate Program in 1998 to provide reapplication assistance to students from economically and/or educationally disadvantaged backgrounds who were previously denied admission to dental school. The goals were to increase diversity in the dental school student population and improve access to dental services for underserved populations. This article assesses the program's short-, mid-, and long-term outcomes and is the first to examine long-term practice patterns after a dental postbaccalaureate program. Data collected on all participant (n=94) demographics, pre/post-program DAT scores, and post-program dental school admission results were used to assess short- and mid-term outcomes. Long-term outcomes and practice patterns were assessed using results of a census survey administered between 2009 and 2011 to the participants who had completed dental school and been in practice for at least two years (n=57). The survey had a response rate of 93 percent (n=53). Descriptive statistical techniques were used to examine the responses and to compare them to U.S. Census Bureau data and nationally available practice data for new dental graduates. Program participants' DAT scores improved by an average of two points, and 98 percent were accepted to dental school. All survey respondents were practicing dentistry, and 81 percent reported serving underserved populations. These participants treat more Medicaid recipients than do most dentists, and their patient population is more diverse than the general population. The outcomes demonstrate that the program's graduates are increasing diversity in the dental student population and that their practices are providing access to care for underserved populations.

  10. Dynamic bandwidth allocation algorithms for local storage based VoD delivery: Comparison between single and dual receiver configurations

    NASA Astrophysics Data System (ADS)

    Abeywickrama, Sandu; Wong, Elaine

    2015-02-01

    The benefits of using distributed caching servers to optimize the traditional video-on-demand delivery have been extensively discussed in literature. In our previous work, we introduced a dual-receiver based dynamic bandwidth allocation algorithm to improve video-on-demand services using a local storage placed within the access network. The main drawback of this algorithm lies in the additional power consumption at the optical network unit that arises from using two receivers. In this paper, we present two novel single-receiver based dynamic bandwidth allocation algorithms to further optimize local storage aided video-on-demand over passive optical networks. The quality-of-service and power performances of the algorithms are critically analyzed using packet level simulations and formulation of power consumption models. We show that the energy-efficiency of a local storage based video-on-demand scheme can be increased without compromising the quality-of-service by the use of single receiver algorithms. Further, we compare the two newly introduced algorithms against dual-receiver based and without local storage schemes to find the most appropriate bandwidth allocation algorithm for local storage based video-on-demand delivery over passive optical networks.

  11. Increasing Access for Economically Disadvantaged Students: The NSF/CSEM & S-STEM Programs at Louisiana State University

    NASA Astrophysics Data System (ADS)

    Wilson, Zakiya S.; Iyengar, Sitharama S.; Pang, Su-Seng; Warner, Isiah M.; Luces, Candace A.

    2012-10-01

    Increasing college degree attainment for students from disadvantaged backgrounds is a prominent component of numerous state and federal legislation focused on higher education. In 1999, the National Science Foundation (NSF) instituted the "Computer Science, Engineering, and Mathematics Scholarships" (CSEMS) program; this initiative was designed to provide greater access and support to academically talented students from economically disadvantaged backgrounds. Originally intended to provide financial support to lower income students, this NSF program also advocated that additional professional development and advising would be strategies to increase undergraduate persistence to graduation. This innovative program for economically disadvantaged students was extended in 2004 to include students from other disciplines including the physical and life sciences as well as the technology fields, and the new name of the program was Scholarships for Science, Technology, Engineering and Mathematics (S-STEM). The implementation of these two programs in Louisiana State University (LSU) has shown significant and measurable success since 2000, making LSU a Model University in providing support to economically disadvantaged students within the STEM disciplines. The achievement of these programs is evidenced by the graduation rates of its participants. This report provides details on the educational model employed through the CSEMS/S-STEM projects at LSU and provides a path to success for increasing student retention rates in STEM disciplines. While the LSU's experience is presented as a case study, the potential relevance of this innovative mentoring program in conjunction with the financial support system is discussed in detail.

  12. Increasing access to kidney transplantation in countries with limited resources: the Indian experience with kidney paired donation.

    PubMed

    Kute, Vivek B; Vanikar, Aruna V; Shah, Pankaj R; Gumber, Manoj R; Patel, Himanshu V; Engineer, Divyesh P; Modi, Pranjal R; Shah, Veena R; Trivedi, Hargovind L

    2014-10-01

    According to the Indian chronic kidney disease registry, in 2010 only 2% of end stage kidney disease patients were managed with kidney transplantation, 37% were managed with dialysis and 61% were treated conservatively without renal replacement therapy. In countries like India, where a well-organized deceased donor kidney transplantation program is not available, living donor kidney transplantation is the major source of organs for kidney transplantation. The most common reason to decline a donor for directed living donation is ABO incompatibility, which eliminates up to one third of the potential living donor pool. Because access to transplantation with human leukocyte antigen (HLA)-desensitization protocols and ABO incompatible transplantation is very limited due to high costs and increased risk of infections from more intense immunosuppression, kidney paired donation (KPD) promises hope to a growing number of end stage kidney disease patients. KPD is a rapidly growing and cost-effective living donor kidney transplantation strategy for patients who are incompatible with their healthy, willing living donor. In principle, KPD is feasible for any centre that performs living donor kidney transplantation. In transplant centres with a large living donor kidney transplantation program KPD does not require extra infrastructure, decreases waiting time, avoids transplant tourism and prevents commercial trafficking. Although KPD is still underutilized in India, it has been performed more frequently in recent times. To substantially increase donor pool and transplant rates, transplant centres should work together towards a national KPD program and frame a uniform acceptable allocation policy.

  13. Demographic population model for American shad: will access to additional habitat upstream of dams increase population sizes?

    USGS Publications Warehouse

    Harris, Julianne E.; Hightower, Joseph E.

    2012-01-01

    American shad Alosa sapidissima are in decline in their native range, and modeling possible management scenarios could help guide their restoration. We developed a density-dependent, deterministic, stage-based matrix model to predict the population-level results of transporting American shad to suitable spawning habitat upstream of dams on the Roanoke River, North Carolina and Virginia. We used data on sonic-tagged adult American shad and oxytetracycline-marked American shad fry both above and below dams on the Roanoke River with information from other systems to estimate a starting population size and vital rates. We modeled the adult female population over 30 years under plausible scenarios of adult transport, effective fecundity (egg production), and survival of adults (i.e., to return to spawn the next year) and juveniles (from spawned egg to age 1). We also evaluated the potential effects of increased survival for adults and juveniles. The adult female population size in the Roanoke River was estimated to be 5,224. With no transport, the model predicted a slow population increase over the next 30 years. Predicted population increases were highest when survival was improved during the first year of life. Transport was predicted to benefit the population only if high rates of effective fecundity and juvenile survival could be achieved. Currently, transported adults and young are less likely to successfully out-migrate than individuals below the dams, and the estimated adult population size is much smaller than either of two assumed values of carrying capacity for the lower river; therefore, transport is not predicted to help restore the stock under present conditions. Research on survival rates, density-dependent processes, and the impacts of structures to increase out-migration success would improve evaluation of the potential benefits of access to additional spawning habitat for American shad.

  14. Efficient traffic grooming with dynamic ONU grouping for multiple-OLT-based access network

    NASA Astrophysics Data System (ADS)

    Zhang, Shizong; Gu, Rentao; Ji, Yuefeng; Wang, Hongxiang

    2015-12-01

    Fast bandwidth growth urges large-scale high-density access scenarios, where the multiple Passive Optical Networking (PON) system clustered deployment can be adopted as an appropriate solution to fulfill the huge bandwidth demands, especially for a future 5G mobile network. However, the lack of interaction between different optical line terminals (OLTs) results in part of the bandwidth resources waste. To increase the bandwidth efficiency, as well as reduce bandwidth pressure at the edge of a network, we propose a centralized flexible PON architecture based on Time- and Wavelength-Division Multiplexing PON (TWDM PON). It can provide flexible affiliation for optical network units (ONUs) and different OLTs to support access network traffic localization. Specifically, a dynamic ONU grouping algorithm (DGA) is provided to obtain the minimal OLT outbound traffic. Simulation results show that DGA obtains an average 25.23% traffic gain increment under different OLT numbers within a small ONU number situation, and the traffic gain will increase dramatically with the increment of the ONU number. As the DGA can be deployed easily as an application running above the centralized control plane, the proposed architecture can be helpful to improve the network efficiency for future traffic-intensive access scenarios.

  15. Ultrawide bandwidth 1.55-um lasers

    NASA Astrophysics Data System (ADS)

    Morton, Paul A.; Tanbun-Ek, Tawee; Logan, Ralph A.; Ackerman, David A.; Shtengel, Gleb E.; Yadvish, R. D.; Sergent, A. M.; Sciortino, Paul F., Jr.

    1996-04-01

    This paper describes the essential elements for creating a practical wide bandwidth directly modulated laser source. This includes considerations of the intrinsic limitations of the laser structure, due to the resonant frequency and damping of the laser output, together with carrier transport issues to allow carriers in the device active region to be efficiently modulated at high speeds. the use of a P-doped compressively strained multiple-quantum well active region to provide high intrinsic speed and remove transport limitations is described, together with record setting results of 25 GHz modulation bandwidth for a 1.55 micrometer Fabry-Perot laser and 26 GHz bandwidth for a 1.55 micrometer DFB laser. The challenges of providing high bandwidth electrical connections to the laser on a suitable submount, together with fiber attachment and microwave packaging, are discussed. Results of fully packaged 1.55 micrometer DFB lasers with 25 Ghz modulation bandwidth are shown. Digital modulation of the packaged 1.55 micrometer DFB including impedance matching is described, and the transient wavelength chirp is presented. This low chirp is reduced further using an optical filter, to provide a 10 GBit/s source with chirp similar to that of an external electroabsorption modulator.

  16. A High Bandwidth Optically Pumped Atomic Magnetometer

    NASA Astrophysics Data System (ADS)

    Jimenez-Martinez, Ricardo; Griffith, Clark W.; Knappe, Svenja; Kitching, John

    2009-10-01

    The measurement of magnetic fields has proved to be relevant in many realms of basic and applied science. Among the different techniques to measure magnetic fields, that of optically pumped atomic magnetometers has experienced considerable attention recently. This interest stems from the development of atomic magnetometers that achieve sensitivities in the sub-femto Tesla range, and the development of techniques that enable highly miniaturized, compact, with low-power consumption magnetometers. The sensitivity and bandwidth of atomic magnetometers is set by their spin coherence time, which in most magnetometers is limited by atomic collisions. Better sensitivities are achieved by suppressing the spin decoherence introduced by atomic collisions, but at a cost of lower bandwidth. For certain applications, a magnetometer with a high bandwidth is useful. Here we present a technique to achieve high bandwidth while preserving high sensitivity. We support the technique with table-top measurements showing that a bandwidth of 10 KHz and sensitivity of 10 pTrms/(Hz)^1/2 can be achieved in a compact device. We also highlight the current development of a miniature atomic magnetometer based on this technique.

  17. Enhanced spectral efficiency using bandwidth switchable SAW filtering for mobile satellite communications systems

    NASA Technical Reports Server (NTRS)

    Peach, Robert; Malarky, Alastair

    1990-01-01

    Currently proposed mobile satellite communications systems require a high degree of flexibility in assignment of spectral capacity to different geographic locations. Conventionally this results in poor spectral efficiency which may be overcome by the use of bandwidth switchable filtering. Surface acoustic wave (SAW) technology makes it possible to provide banks of filters whose responses may be contiguously combined to form variable bandwidth filters with constant amplitude and phase responses across the entire band. The high selectivity possible with SAW filters, combined with the variable bandwidth capability, makes it possible to achieve spectral efficiencies over the allocated bandwidths of greater than 90 percent, while retaining full system flexibility. Bandwidth switchable SAW filtering (BSSF) achieves these gains with a negligible increase in hardware complexity.

  18. Effects of large laser bandwidth on stimulated Raman scattering instability in underdense plasma

    SciTech Connect

    Zhao, Yao; Yu, Lu-Le; Zheng, Jun; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming E-mail: zhengming.sheng@strath.ac.uk

    2015-05-15

    The effects of laser bandwidth on stimulated Raman scattering (SRS) instability in underdense plasma are studied by particle-in-cell simulations. In the simulations, sinusoidal frequency modulation of the incident laser pulse is used. By changing the size of bandwidth, it is shown that the linear growth of SRS can be suppressed considerably, provided the laser bandwidth is much larger than the SRS linear growth rate. Simulations also show that by choosing the proper frequency modulation parameters or decreasing the linear growth rate of SRS, the inhibitory effects become more obvious. The plasma electron temperature tends to weaken the bandwidth effects especially when it is over a keV level. The laser bandwidth can only increase the time duration for linear growth but cannot diminish the instability completely.

  19. 2.06 Micrometer Wide Bandwidth Detector Assembly.

    DTIC Science & Technology

    1981-02-01

    limited to its photon response time in both the voltage and current mode. Operating a photoconductor in the current mode will not increase the response...Factor 30 9i I’ .- ~.... i. ABSTRACT This program demonstrated that high performance, wide bandwidth mercury cadmium telluride photoconductor detectors...Mercury Cadmium Telluride crystals with a mole fraction of .475 and a majority carrier concentration of less than 1 x 1014cm-3 . The crystal grown

  20. Optimal bandwidth for high efficiency thermoelectrics.

    PubMed

    Zhou, Jun; Yang, Ronggui; Chen, Gang; Dresselhaus, Mildred S

    2011-11-25

    The thermoelectric figure of merit (ZT) in narrow conduction bands of different material dimensionalities is investigated for different carrier scattering models. When the bandwidth is zero, the transport distribution function (TDF) is finite, not infinite as previously speculated by Mahan and Sofo [Proc. Natl. Acad. Sci. U.S.A. 93, 7436 (1996)], even though the carrier density of states goes to infinity. Such a finite TDF results in a zero electrical conductivity and thus a zero ZT. We point out that the optimal ZT cannot be found in an extremely narrow conduction band. The existence of an optimal bandwidth for a maximal ZT depends strongly on the scattering models and the dimensionality of the material. A nonzero optimal bandwidth for maximizing ZT also depends on the lattice thermal conductivity. A larger maximum ZT can be obtained for materials with a smaller lattice thermal conductivity.

  1. 47 CFR 90.209 - Bandwidth limitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth limitations. 90.209 Section 90.209... bandwidth (kHz) Below 25 2 25-50 20 20 72-76 20 20 150-174 17.5 1,3 20/11.25/6 216-220 5 6.25 20/11.25/6 220-222 5 4 406-512 2 1 6.25 1,3 20/11.25/6 806-809/851-854 12.5 20 809-824/854-869 25 20...

  2. An enhanced dynamic wavelength and bandwidth allocation method in WDM-EPON

    NASA Astrophysics Data System (ADS)

    Zeng, Zhiwei; Ran, Yang; Huang, Hongbin; Liu, Weiping

    2009-11-01

    A kind of dynamic wavelength and bandwidth allocation (DWBA) algorithm of WDM-EPON was studied and then improved to guarantee QoS of multiple-services access. MPCP extension with modified REQUEST message and GRANT message are also proposed.The simulation results based on OPNET indicates the improved algorithm performed well in successful QoS assurance.

  3. The politics behind the implementation of the WTO Paragraph 6 Decision in Canada to increase global drug access

    PubMed Central

    2012-01-01

    accounted for by experience in implementing the legislation and hence a greater representation of the interests of potential beneficiary country governments. Conclusions The Canadian Government designed CAMR as a last resort measure. Increased input from the developing country beneficiaries and shifting to institutions where the right to health gets prioritized may lead to policies that better achieves affordable drug access. PMID:22472291

  4. 47 CFR 87.135 - Bandwidth of emission.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth of emission. 87.135 Section 87.135... Technical Requirements § 87.135 Bandwidth of emission. (a) Occupied bandwidth is the width of a frequency... equal to 0.5 percent of the total mean power of a given emission. (b) The authorized bandwidth is...

  5. 47 CFR 87.135 - Bandwidth of emission.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth of emission. 87.135 Section 87.135... Technical Requirements § 87.135 Bandwidth of emission. (a) Occupied bandwidth is the width of a frequency... equal to 0.5 percent of the total mean power of a given emission. (b) The authorized bandwidth is...

  6. 47 CFR 87.135 - Bandwidth of emission.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth of emission. 87.135 Section 87.135... Technical Requirements § 87.135 Bandwidth of emission. (a) Occupied bandwidth is the width of a frequency... equal to 0.5 percent of the total mean power of a given emission. (b) The authorized bandwidth is...

  7. Overcoming inertia: increasing public health departments' access to evidence-based information and promoting usage to inform practice.

    PubMed

    LaPelle, Nancy R; Dahlen, Karen; Gabella, Barbara A; Juhl, Ashley L; Martin, Elaine

    2014-01-01

    In 2010, the New England Region-National Network of Libraries of Medicine at University of Massachusetts Medical School received funding to improve information access for public health departments in 6 New England states and Colorado. Public health departments were provided with desktop digital access to licensed e-resources available through special pricing. In January through mid-April 2012, we evaluated the effectiveness of providing access to and training for using e-resources to public health department staff to motivate usage in practice. We found that additional strategies are needed to accomplish this.

  8. Compact silicon multimode waveguide spectrometer with enhanced bandwidth

    PubMed Central

    Piels, Molly; Zibar, Darko

    2017-01-01

    Compact, broadband, and high-resolution spectrometers are appealing for sensing applications, but difficult to fabricate. Here we show using calibration data a spectrometer based on a multimode waveguide with 2 GHz resolution, 250 GHz bandwidth, and a 1.6 mm × 2.1 mm footprint. Typically, such spectrometers have a bandwidth limited by the number of modes supported by the waveguide. In this case, an on-chip mode-exciting element is used to repeatably excite distinct collections of waveguide modes. This increases the number of independent spectral channels from the number of modes to this number squared, resulting in an extension of the usable range. PMID:28290537

  9. Wide-Bandwidth Digital Backend System for VLBI

    NASA Astrophysics Data System (ADS)

    Whitney, A. R.

    2007-07-01

    Modern digital electronics now allow the replacement of aging VLBI analog backend systems with fully digital systems to provide numerous benefits, including: 1) uniform, repeatable, predictable performance, 2) low cost, 3) increased flexibility, 4) easy expandability, 6) easy transportability, and 5) flexible and rapid implementation through use of modern FPGA devices. A first-generation Digital Backend (DBE) system, based on a polyphase-filter-bank approach that can process four 500 MHz-bandwidth IF signals, has been built (for <15K), tested, and exercised in real-world VLBI experiments at rates to 4 Gbps/station. Tests at 8 Gbps/station are planned. A second-generation DBE system to process four 1 GHz-bandwidth IFs is now in development in collaboration with UC Berkeley and National Radio Astronomy Observatory; the cost of this system is expected to <10K.

  10. Optical interconnect technologies for high-bandwidth ICT systems

    NASA Astrophysics Data System (ADS)

    Chujo, Norio; Takai, Toshiaki; Mizushima, Akiko; Arimoto, Hideo; Matsuoka, Yasunobu; Yamashita, Hiroki; Matsushima, Naoki

    2016-03-01

    The bandwidth of information and communication technology (ICT) systems is increasing and is predicted to reach more than 10 Tb/s. However, an electrical interconnect cannot achieve such bandwidth because of its density limits. To solve this problem, we propose two types of high-density optical fiber wiring for backplanes and circuit boards such as interface boards and switch boards. One type uses routed ribbon fiber in a circuit board because it has the ability to be formed into complex shapes to avoid interfering with the LSI and electrical components on the board. The backplane is required to exhibit high density and flexibility, so the second type uses loose fiber. We developed a 9.6-Tb/s optical interconnect demonstration system using embedded optical modules, optical backplane, and optical connector in a network apparatus chassis. We achieved 25-Gb/s transmission between FPGAs via the optical backplane.

  11. Pulse Shaped 8-PSK Bandwidth Efficiency and Spectral Spike Elimination

    NASA Technical Reports Server (NTRS)

    Tao, Jian-Ping

    1998-01-01

    The most bandwidth-efficient communication methods are imperative to cope with the congested frequency bands. Pulse shaping methods have excellent effects on narrowing bandwidth and increasing band utilization. The position of the baseband filters for the pulse shaping is crucial. Post-modulation pulse shaping (a low pass filter is located after the modulator) can change signals from constant envelope to non-constant envelope, and non-constant envelope signals through non-linear device (a SSPA or TWT) can further spread the power spectra. Pre-modulation pulse shaping (a filter is located before the modulator) will have constant envelope. These two pulse shaping methods have different effects on narrowing the bandwidth and producing bit errors. This report studied the effect of various pre-modulation pulse shaping filters with respect to bandwidth, spectral spikes and bit error rate. A pre-modulation pulse shaped 8-ary Phase Shift Keying (8PSK) modulation was used throughout the simulations. In addition to traditional pulse shaping filters, such as Bessel, Butterworth and Square Root Raised Cosine (SRRC), other kinds of filters or pulse waveforms were also studied in the pre-modulation pulse shaping method. Simulations were conducted by using the Signal Processing Worksystem (SPW) software package on HP workstations which simulated the power spectral density of pulse shaped 8-PSK signals, end to end system performance and bit error rates (BERS) as a function of Eb/No using pulse shaping in an AWGN channel. These results are compared with the post-modulation pulse shaped 8-PSK results. The simulations indicate traditional pulse shaping filters used in pre-modulation pulse shaping may produce narrower bandwidth, but with worse BER than those in post-modulation pulse shaping. Theory and simulations show pre- modulation pulse shaping could also produce discrete line power spectra (spikes) at regular frequency intervals. These spikes may cause interference with adjacent

  12. 47 CFR 80.205 - Bandwidths.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... necessary bandwidth for each class of emission of a station except that in ship earth stations it shows the... communications with private coast stations. 5 NB-DP radiotelegraph and data transmissions for communications...

  13. 47 CFR 80.205 - Bandwidths.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES STATIONS IN THE... necessary bandwidth for each class of emission of a station except that in ship earth stations it shows the... communications with private coast stations. 5 NB-DP radiotelegraph and data transmissions for communications...

  14. High bandwidth vapor density diagnostic system

    DOEpatents

    Globig, Michael A.; Story, Thomas W.

    1992-01-01

    A high bandwidth vapor density diagnostic system for measuring the density of an atomic vapor during one or more photoionization events. The system translates the measurements from a low frequency region to a high frequency, relatively noise-free region in the spectrum to provide improved signal to noise ratio.

  15. Kernel bandwidth optimization in spike rate estimation.

    PubMed

    Shimazaki, Hideaki; Shinomoto, Shigeru

    2010-08-01

    Kernel smoother and a time-histogram are classical tools for estimating an instantaneous rate of spike occurrences. We recently established a method for selecting the bin width of the time-histogram, based on the principle of minimizing the mean integrated square error (MISE) between the estimated rate and unknown underlying rate. Here we apply the same optimization principle to the kernel density estimation in selecting the width or "bandwidth" of the kernel, and further extend the algorithm to allow a variable bandwidth, in conformity with data. The variable kernel has the potential to accurately grasp non-stationary phenomena, such as abrupt changes in the firing rate, which we often encounter in neuroscience. In order to avoid possible overfitting that may take place due to excessive freedom, we introduced a stiffness constant for bandwidth variability. Our method automatically adjusts the stiffness constant, thereby adapting to the entire set of spike data. It is revealed that the classical kernel smoother may exhibit goodness-of-fit comparable to, or even better than, that of modern sophisticated rate estimation methods, provided that the bandwidth is selected properly for a given set of spike data, according to the optimization methods presented here.

  16. 47 CFR 2.202 - Bandwidths.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... carry either single sideband suppressed carrier frequency division multiplex speech channels or... (Commercial Quality) Telephony double-sideband Bn=2M M=3000, Bandwidth=6000 Hz=6 kHz 6K00A3E Telephony, single... demodulated speech signal, single-sideband, reduced carrier Bn=M Maximum control frequency is 2990 Hz,...

  17. Bandwidth Enabled Flight Operations: Examining the Possibilities

    NASA Technical Reports Server (NTRS)

    Pisanich, Greg; Renema, Fritz; Clancy, Dan (Technical Monitor)

    2002-01-01

    The Bandwidth Enabled Flight Operations project is a research effort at the NASA Ames Research Center to investigate the use of satellite communications to improve aviation safety and capacity. This project is a follow on to the AeroSAPIENT Project, which demonstrated methods for transmitting high bandwidth data in various configurations. For this research, we set a goal to nominally use only 10 percent of the available bandwidth demonstrated by AeroSAPIENT or projected by near-term technology advances. This paper describes the results of our research, including available satellite bandwidth, commercial and research efforts to provide these services, and some of the limiting factors inherent with this communications medium. It also describes our investigation into the needs of the stakeholders (Airlines, Pilots, Cabin Crews, ATC, Maintenance, etc). The paper also describes our development of low-cost networked flight deck and airline operations center simulations that were used to demonstrate two application areas: Providing real time weather information to the commercial flight deck, and enhanced crew monitoring and control for airline operations centers.

  18. Power and bandwidth efficient modulation techniques

    NASA Astrophysics Data System (ADS)

    Le-Ngoc, T.; Feher, K.

    In this invited paper, a literature survey of power and bandwidth efficient modulation techniques is presented in historical progression from the widely known QPSK, OQPSK, and MSK to recently developed digital 4-phase modulation schemes. This historical review provides some insight into understanding the motivation, evolution and results of the development of new digital 4-phase modulation schemes applied to nonlinear channels.

  19. Adaptation of AMO-FBMC-OQAM in optical access network for accommodating asynchronous multiple access in OFDM-based uplink transmission

    NASA Astrophysics Data System (ADS)

    Jung, Sun-Young; Jung, Sang-Min; Han, Sang-Kook

    2015-01-01

    Exponentially expanding various applications in company with proliferation of mobile devices make mobile traffic exploded annually. For future access network, bandwidth efficient and asynchronous signals converged transmission technique is required in optical network to meet a huge bandwidth demand, while integrating various services and satisfying multiple access in perceived network resource. Orthogonal frequency division multiplexing (OFDM) is highly bandwidth efficient parallel transmission technique based on orthogonal subcarriers. OFDM has been widely studied in wired-/wireless communication and became a Long term evolution (LTE) standard. Consequently, OFDM also has been actively researched in optical network. However, OFDM is vulnerable frequency and phase offset essentially because of its sinc-shaped side lobes, therefore tight synchronism is necessary to maintain orthogonality. Moreover, redundant cyclic prefix (CP) is required in dispersive channel. Additionally, side lobes act as interference among users in multiple access. Thus, it practically hinders from supporting integration of various services and multiple access based on OFDM optical transmission In this paper, adaptively modulated optical filter bank multicarrier system with offset QAM (AMO-FBMC-OQAM) is introduced and experimentally investigated in uplink optical transmission to relax multiple access interference (MAI), while improving bandwidth efficiency. Side lobes are effectively suppressed by using FBMC, therefore the system becomes robust to path difference and imbalance among optical network units (ONUs), which increase bandwidth efficiency by reducing redundancy. In comparison with OFDM, a signal performance and an efficiency of frequency utilization are improved in the same experimental condition. It enables optical network to effectively support heterogeneous services and multiple access.

  20. DC SQUID RF magnetometer with 200 MHz bandwidth

    NASA Astrophysics Data System (ADS)

    Talanov, Vladimir; Lettsome, Nesco; Orozco, Antonio; Cawthorne, Alfred; Borzenets, Valery

    2012-02-01

    Because of periodic flux-to-voltage transfer function, Superconducting QUantum Interference Device (SQUID) magnetometers operate in a closed-loop regime [1], which linearizes the response, and increases the dynamic range and sensitivity. However, a transmission line delay between the SQUID and electronics fundamentally limits the closed-loop bandwidth at 20 MHz [1], although the intrinsic bandwidth of SQUIDs is in gigahertz range. We designed a DC SQUID based RF magnetometer capable of wideband sensing coherent magnetic fields up to 200 MHz. To overcome the closed-loop bandwidth limitation, we utilized a low-frequency flux-modulated closed-loop to simultaneously lock the quasi-static magnetic flux and provide AC bias for the RF flux. The SQUID RF voltage is processed by RF electronics based on a double lock-in technique. This yields a signal proportional to the amplitude and phase of the RF magnetic flux, with more than four decades of a linear response. For YBaCuO SQUID on bi-crystal SrTiO substrate at 77 K we achieved a flux noise density of 4 μφ0/Hz at 190 MHz, which is similar to that measured at kHz frequencies with conventional flux-locked loop. [1] D. Drung, et al., Supercond. Sci. Technol. 19, S235 (2006).

  1. Establishing access to technology: an evaluation and intervention model to increase the participation of children with cerebral palsy.

    PubMed

    McCarty, Elizabeth; Morress, Claire

    2009-08-01

    Children with a diagnosis of cerebral palsy often have significant physical limitations that prevent exploration and full participation in the environment. Assistive technology systems can provide opportunities for children with physical limitations to interact with their world, enabling play, communication, and daily living skills. Efficient access to and control of the technology is critical for successful use; however, establishing consistent access is often difficult because of the nature of the movement patterns exhibited by children with cerebral palsy. This article describes a 3-phase model of evaluation and intervention developed and used by Assistive Technology Services at the Aaron W. Perlman Center, Cincinnati Children's Hospital Medical Center, to establish successful access to technology systems in children with cerebral palsy.

  2. Guidelines for Outsourcing Remote Access.

    ERIC Educational Resources Information Center

    Hassler, Ardoth; Neuman, Michael

    1996-01-01

    Discusses the advantages and disadvantages of outsourcing remote access to campus computer networks and the Internet, focusing on improved service, cost-sharing, partnerships with vendors, supported protocols, bandwidth, scope of access, implementation, support, network security, and pricing. Includes a checklist for a request for proposals on…

  3. Bandwidth-sharing in LHCONE, an analysis of the problem

    NASA Astrophysics Data System (ADS)

    Wildish, T.

    2015-12-01

    The LHC experiments have traditionally regarded the network as an unreliable resource, one which was expected to be a major source of errors and inefficiency at the time their original computing models were derived. Now, however, the network is seen as much more capable and reliable. Data are routinely transferred with high efficiency and low latency to wherever computing or storage resources are available to use or manage them. Although there was sufficient network bandwidth for the experiments’ needs during Run-1, they cannot rely on ever-increasing bandwidth as a solution to their data-transfer needs in the future. Sooner or later they need to consider the network as a finite resource that they interact with to manage their traffic, in much the same way as they manage their use of disk and CPU resources. There are several possible ways for the experiments to integrate management of the network in their software stacks, such as the use of virtual circuits with hard bandwidth guarantees or soft real-time flow-control, with somewhat less firm guarantees. Abstractly, these can all be considered as the users (the experiments, or groups of users within the experiment) expressing a request for a given bandwidth between two points for a given duration of time. The network fabric then grants some allocation to each user, dependent on the sum of all requests and the sum of available resources, and attempts to ensure the requirements are met (either deterministically or statistically). An unresolved question at this time is how to convert the users’ requests into an allocation. Simply put, how do we decide what fraction of a network's bandwidth to allocate to each user when the sum of requests exceeds the available bandwidth? The usual problems of any resourcescheduling system arise here, namely how to ensure the resource is used efficiently and fairly, while still satisfying the needs of the users. Simply fixing quotas on network paths for each user is likely to lead

  4. In the United States, "Opt-Out" States Show No Increase in Access to Anesthesia Services for Medicare Beneficiaries Compared with Non-"Opt-Out" States.

    PubMed

    Sun, Eric C; Miller, Thomas R; Halzack, Nicholas M

    2016-05-01

    In the United States, anesthesia care can be provided by anesthesiologists or nurse anesthetists. Since 2001, 17 states have exercised their right to "opt-out" of the federal requirement that a physician supervise the administration of anesthesia by a nurse anesthetist, with the majority citing increased access to anesthesia care as the rationale for their decision. By using Medicare data, we found that most (4 of 5) cohorts of "opt-out" states likely experienced smaller growth in anesthesia utilization rates compared with non-"opt-out" states, suggesting that opt-out was not associated with an increase in access to anesthesia care.

  5. How Do Members of Different Stakeholder Groups Balance Concerns for Increasing Access with Improving Quality in the Tanzania Education System?

    ERIC Educational Resources Information Center

    Telli, Godfrey

    2012-01-01

    The purpose of this study was to explore how education stakeholders in Tanzania express and balance their priorities, perspectives, and concerns regarding the expansion of education access on the one hand, and improving quality of education on the other, as a means to enhance educational achievement. The study also explores how each group of…

  6. Summary of Regional Conferences: Increasing Minority Access to the Licensed Professions through Two-Year College Programs.

    ERIC Educational Resources Information Center

    State Univ. of New York, Albany. Two Year Coll. Development Center.

    In 1984-85, a cooperative project was undertaken in New York to address the issue of minority access to those professions that can be entered through two-year college programs (e.g., animal health technology, certified shorthand reporting, dental hygienist, land surveying, and physical therapist assistant). Project activities were guided by a…

  7. Increasing Accessibility to Historical Collections: Micropublishing the Early Modern Maps and Drawings of the General State Archives of the Netherlands.

    ERIC Educational Resources Information Center

    Moran, Gerard T.

    1995-01-01

    Discusses the project undertaken by MMF Publications to micropublish a collection of rare Dutch maps and drawings. Background information about the collection is given and decisions regarding the choice of microfiche format are explained. MMF elected to publish a printed guide to accompany the collection for enhanced access. (Author/JKP)

  8. Reconstitution of Low Bandwidth Reaction History

    SciTech Connect

    May, M; Clancy, T; Fittinghoff, D; Gennaro, P; Hagans, K; Halvorson, G; Lowry, M; Perry, T; Roberson, P; Smith, D; Teruya, A; Blair, J; Davis, B; Hunt, E; Emkeit, B; Galbraith, J; Kelly, B; Montoya, R; Nickel, G; Ogle, J; Wilson, K; Wood, M

    2004-11-11

    The goal of the Test Readiness Program is to transition to a 24 month test readiness posture and if approved move to an 18-month posture. One of the key components of the Test Readiness Program necessary to meet this goal is the reconstitution of the important diagnostics. Since the end of nuclear testing, the ability to field diagnostics on a nuclear test has deteriorated. Reconstitution of diagnostics before those who had experience in nuclear testing either retire or leave is essential to achieving a shorter test readiness posture. Also, the data recording systems have not been used since the end of testing. This report documents the reconstitution of one vital diagnostic: the low bandwidth reaction history diagnostic for FY04. Reaction history is one of the major diagnostics that has been used on all LLNL and LANL tests since the early days of nuclear testing. Reaction history refers to measuring the time history of the gamma and neutron output from a nuclear test. This gives direct information on the nuclear reactions taking place in the device. The reaction history measurements are one of the prime measurements the nuclear weapon scientists use to validate their models of device performance. All tests currently under consideration require the reaction history diagnostic. Thus moving to a shorter test readiness posture requires the reconstitution of the ability to make reaction history measurements. Reconstitution of reaction history was planned to be in two steps. Reaction history measurements that have been used in the past can be broadly placed into two categories. The most common type of reaction history and the one that has been performed on virtually all nuclear tests is termed low bandwidth reaction history. This measurement has a time response that is limited by the bandpass of kilometer length coaxial cables. When higher bandwidth has been required for specific measurements, fiber optic techniques have been used. This is referred to as high-bandwidth

  9. Bandwidth tunable amplifier for recording biopotential signals.

    PubMed

    Hwang, Sungkil; Aninakwa, Kofi; Sonkusale, Sameer

    2010-01-01

    This paper presents a low noise, low power, bandwidth tunable amplifier for bio-potential signal recording applications. By employing depletion-mode pMOS transistor in diode configuration as a tunable sub pA current source to adjust the resistivity of MOS-Bipolar pseudo-resistor, the bandwidth is adjusted without any need for a separate band-pass filter stage. For high CMRR, PSRR and dynamic range, a fully differential structure is used in the design of the amplifier. The amplifier achieves a midband gain of 39.8dB with a tunable high-pass cutoff frequency ranging from 0.1Hz to 300Hz. The amplifier is fabricated in 0.18εm CMOS process and occupies 0.14mm(2) of chip area. A three electrode ECG measurement is performed using the proposed amplifier to show its feasibility for low power, compact wearable ECG monitoring application.

  10. High Bandwidth Differential Amplifier for Shock Experiments

    SciTech Connect

    Ross, P. W., Tran, V., Chau, R.

    2012-04-30

    We developed a high bandwidth differential amplifier for gas gun shock experiments/applications. The circuit has a bandwidth > 1 GHz, and is capable of measuring signals of ≤1.5 V with a common mode rejection of 250 V. Conductivity measurements of gas gun targets are measured by flowing high currents through the targets. The voltage is measured across the target using a technique similar to a four-point probe. Because of the design of the current source and load, the target voltage is approximately 250 V relative to ground. Since the expected voltage change in the target is < 1 V, the differential amplifier must have a large common mode rejection. High pass filters suppress internal ringing of operational amplifiers. Results of bench tests are shown.

  11. Understanding Bandwidth Limitations in Robot Force Control.

    DTIC Science & Technology

    1987-08-01

    we have the root locus plot shape (for varying kf) drawn in Figure 17. The PI controller adds a pole at the origin and * adds a zero at s-k...implementation analysis are: w. * Digital effects are significant, but should not present a problem in modem computer-based systems. *Low-pass filtering and PI ... control add destabilizing poles, which introduce phase lag and limit closed-loop bandwidth. 6 * PD control and lead compensation add zeros which

  12. Bandwidth and SIMDUCE as simulator fidelity criteria

    NASA Technical Reports Server (NTRS)

    Key, David

    1992-01-01

    The potential application of two concepts from the new Handling Qualities Specification for Military Rotorcraft was discussed. The first concept is bandwidth, a measure of the dynamic response to control. The second is a qualitative technique developed for assessing the visual cue environment the pilot has in bad weather and at night. Simulated Day Usable Cue Environment (SIMDUCE) applies this concept to assessing the day cuing fidelity in the simulator.

  13. Analysis of blocking rate and bandwidth usage of mobile IPTV services in wireless cellular networks.

    PubMed

    Li, Mingfu

    2014-01-01

    Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes.

  14. Analysis of Blocking Rate and Bandwidth Usage of Mobile IPTV Services in Wireless Cellular Networks

    PubMed Central

    Li, Mingfu

    2014-01-01

    Mobile IPTV services over wireless cellular networks become more and more popular, owing to the significant growth in access bandwidth of wireless cellular networks such as 3G/4G and WiMAX. However, the spectrum resources of wireless cellular networks is rare. How to enhance the spectral efficiency of mobile networks becomes an important issue. Unicast, broadcast, and multicast are the most important transport schemes for offering mobile IPTV services over wireless cellular networks. Therefore, bandwidth usages and blocking rates of unicast, broadcast, and multicast IPTV services were analyzed and compared in this paper. Simulations were also conducted to validate the analytical results. Numerical results demonstrate that the presented analysis is correct, and multicast scheme achieves the best bandwidth usage and blocking rate performance, relative to the other two schemes. PMID:25379521

  15. Application migration to reserved bandwidth networks

    NASA Astrophysics Data System (ADS)

    Stirpe, Paul A.; Verma, Dinesh C.

    1995-03-01

    The advent of high speed networks has stimulated development and deployment of many new distributed applications, such as multiparty video conferencing. At the same time, the networking community is rapidly moving towards new high speed networking architectures that offer advanced features such as guaranteed bandwidth and connection performance guarantees. The performance of may applications would be improved significantly if features offered by these new networks are utilized. While it is desirable to use the features of the new protocols provided by the emerging high speed networks, these protocols have not yet reached the same degree of stability and maturity as the existing protocols. As new networks with advanced features are deployed, schemes that take advantage of the advanced network capabilities, are necessary to migrate existing applications to the new networking interfaces. In this paper, several application migration paths are outlined. The concept of a Bandwidth Server, that provides transparent application migration, is introduced, e.g. transparent migration does not require an application to be rewritten, recompiled, or relinked. We explore the design of a simple and efficient Bandwidth Server that allows TCP/IP applications, written using the well-known socket-interface, to execute across a B-ISDN network.

  16. An improved scheduled traffic model utilizing bandwidth splitting in elastic optical networks

    NASA Astrophysics Data System (ADS)

    Vyas, Upama; Prakash, Shashi

    2016-07-01

    The surge of traffic in today's networks gave birth to elastic optical networking paradigm. In this paper, first we propose to use the scheduled traffic model (STM) in elastic optical networks (EONs) to ensure guaranteed availability of resources to demands which enter into the network with a predetermined start and end times. In optical networks, such demands are referred to as scheduled lightpath demands (SLDs). To increase the amount of bandwidth accepted in network, next we introduce a time aware routing and spectrum assignment (TA-RSA) approach. We observed that provisioning of bulky SLDs has become more challenging in EONs due to enforcement of RSA constraints. To address this challenge, we improve the proposed STM and designed three heuristics for its implementation in EONs. In this work, we collectively refer to these heuristics as bandwidth segmented RSA (BSRSA). The improved STM (iSTM) allows splitting of SLDs in bandwidth dimension by utilizing the knowledge of attributes viz. demand holding time, overlapping in time and bandwidth requested by SLDs. Our numerical results show that BSRSA consistently outperformed over TA-RSA under all distinctive experimental cases that we considered and achieved fairness in serving heterogeneous bandwidth SLDs. The impact of splitting on the number and capacity of transponders at nodes is also gauged. It is observed that ingenious splitting of demands increases the number of resources (on links and nodes) used, and their utilization, leading to an increase in bandwidth accepted in the network.

  17. Dynamic MTW: a dynamic bandwidth distribution scheme in EPON

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Ge, Liangwei; Zeng, Lieguang

    2002-08-01

    An algorithm to improve the bandwidth utilization for EPON by using dynamic bandwidth distribution is put forward. System performance, such as queuing delay under self-similar traffic, is simulated by using OPNET.

  18. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  19. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  20. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  1. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  2. 47 CFR 2.1049 - Measurements required: Occupied bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ....1049 Section 2.1049 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1049 Measurements required: Occupied bandwidth. The occupied bandwidth, that is the...

  3. The effective I/O bandwidth benchmark (b{_}eff{_}io)

    SciTech Connect

    Koniges, A E; Rabehseifner, R

    2000-02-17

    The effective I/O bandwidth benchmark (b{_}eff{_}io) covers two goals: (1) to achieve a characteristic average number for the I/O bandwidth achievable with parallel MPI-I/O applications, and (2) to get detailed information about several access patterns and buffer lengths. The benchmark examines ''first write'', ''rewrite'' and ''read'' access, strided (individual and shared pointers) and segmented collective patterns on one file per application and non-collective access to one file per process. The number of parallel accessing processes is also varied and wellformed I/O is compared with non-wellformed. On systems, meeting the rule that the total memory can be written to disk in 10 minutes, the benchmark should not need more than 15 minutes for a first pass of all patterns. The benchmark is designed analogously to the effective bandwidth benchmark for message passing (b{_}eff) that characterizes the message passing capabilities of a system in a few minutes. First results of the b{_}elf{_}io benchmark are given for IBM SP and Cray T3E systems and compared with existing benchmarks based on parallel Posix-I/O.

  4. Spectrophotometer spectral bandwidth calibration with absorption bands crystal standard.

    PubMed

    Soares, O D; Costa, J L

    1999-04-01

    A procedure for calibration of a spectral bandwidth standard for high-resolution spectrophotometers is described. Symmetrical absorption bands for a crystal standard are adopted. The method relies on spectral band shape fitting followed by a convolution with the slit function of the spectrophotometer. A reference spectrophotometer is used to calibrate the spectral bandwidth standard. Bandwidth calibration curves for a minimum spectral transmission factor relative to the spectral bandwidth of the reference spectrophotometer are derived for the absorption bands at the wavelength of the band absorption maximum. The family of these calibration curves characterizes the spectral bandwidth standard. We calibrate the spectral bandwidth of a spectrophotometer with respect to the reference spectrophotometer by determining the spectral transmission factor minimum at every calibrated absorption band of the bandwidth standard for the nominal instrument values of the spectral bandwidth. With reference to the standard spectral bandwidth calibration curves, the relation of the spectral bandwidth to the reference spectrophotometer is determined. We determine the discrepancy in the spectrophotometers' spectral bandwidths by averaging the spectral bandwidth discrepancies relative to the standard calibrated values found at the absorption bands considered. A weighted average of the uncertainties is taken.

  5. Paying the price works: increasing goal-state access cost improves problem solving and mitigates the effect of interruption.

    PubMed

    Morgan, Phillip L; Patrick, John

    2013-01-01

    The aim of this paper was to investigate whether it was possible to induce more internal planning in the four-disk Tower of Hanoi (ToH) in order not only to produce more efficient problem solving but also to make it more resistant to the negative effect of interruption. The theoretical frameworks of soft constraints and the memory for goals model underpinned Experiments 1 and 2. In both experiments, three goal-state access cost conditions were used: high (mouse movements and 2.5-s delay), medium (mouse movements) and low (goal state always available). In Experiment 1, more memory-based planning was induced by the high cost condition, which resulted in fewer moves to solution and the gradual development of an efficient subgoaling strategy, resulting in more perfect solutions. In Experiment 2, the same condition protected performance against a 10-s interruption irrespective of the interrupting task (blank screen, mental arithmetic, or three-disk ToH). The more memory-based planning strategy, induced by high access cost, presumably strengthened participants' goals during planning and problem solving, making them less susceptible to decay and interference from interruption. These novel results are discussed in the context of other recent studies.

  6. Hone filter bandwidth with computer ease

    NASA Astrophysics Data System (ADS)

    Crawford, J.

    1986-01-01

    It is pointed out that programmable calculators and computers address a variety of difficult problems which were too small for the large mainframe computer. An example for such problems represents the selection of the optimum bandwidth for a bandpass filter. It is now possible to evaluate filter performance quickly and accurately by making use of simple computer procedures which replace time-consuming filter nomographs and other estimation techniques. The computerized technique for evaluating filters permits optimum selection of a passband which concurrently satisfies specified stopband requirements. Attention is given to results of sample filter calculation, the passband maximizer, and tracking losses.

  7. Frequency division multiple transmission method to utilize the wide bandwidth property of capacitive micromachined ultrasonic transducer arrays

    NASA Astrophysics Data System (ADS)

    Lee, Seunghun; Kim, Bae-Hyung; Jeon, Taeho; Kim, Youngil; Cho, Kyungil; Song, Jongkeun

    2013-03-01

    CMUT-on-ASIC integration techniques are promising for the development of lower cost smaller volume scanners with higher performance in terms of features and image qualities because it minimizes parasitic capacitances and ultimately improves signal-to-noise ratio (SNR). Moreover, a frequency bandwidth of CMUT array is known as relatively broader than that of other ultrasonic transducer arrays. To utilize the wide bandwidth characteristic of the CMUT arrays, in this paper, we introduce a FDMA (frequency division multiple access) based ultrasound imaging technique using orthogonally band-divided coded signals to provide dynamic transmit focused imaging without sacrificing the frame rate. In the presented method, the orthogonal sub-band coded signals are simultaneously fired on multiple ranges, in which each signal is focused at a different range, in one transmission event. This paper also presents an ultrasound imageformation method and a modulation and demodulation process of orthogonal sub-band coded signals designed within the frequency bandwidth of the CMUT arrays. The presented method is verified by computer simulations using Field II and experiments. The simulation results using a computer generated tissue mimicking phantom show that the presented method can be achieved with both increased image quality and frame rate. The experimental results to verify the feasibility of the presented method using orthogonal sub-band coded signals show that the reflected signals from targets are successfully separated into two compressed signals. Currently, we are extending the presented approach to ultrasound imaging technique for volumetric ultrasound scanners using 2-D CMUT-on-ASIC arrays.

  8. Increasing Reading/Literacy Performance of At-Risk Elementary Students through Increased Access to Fiction/Non-Fiction Resources and Incorporating Readers Theater Activities

    ERIC Educational Resources Information Center

    Salas, Gayla L.

    2008-01-01

    This action research project was developed in order to increase student literacy, particularly in the area of reading, for students who were considered at-risk. The targeted student population was 2nd grade students who were served within a primary cross-categorical special education program. The classroom was housed in an elementary (K-2) school,…

  9. Reduced burden of childhood diarrheal diseases through increased access to water and sanitation in India: A modeling analysis.

    PubMed

    Nandi, Arindam; Megiddo, Itamar; Ashok, Ashvin; Verma, Amit; Laxminarayan, Ramanan

    2016-08-31

    Each year, more than 300,000 children in India under the age of five years die from diarrheal diseases. Clean piped water and improved sanitation are known to be effective in reducing the mortality and morbidity burden of diarrhea but are not yet available to close to half of the Indian population. In this paper, we estimate the health benefits (reduced cases of diarrheal incidence and deaths averted) and economic benefits (measured by out-of-pocket treatment expenditure averted and value of insurance gained) of scaling up the coverage of piped water and improved sanitation among Indian households to a near-universal 95% level. We use IndiaSim, a previously validated, agent-based microsimulation platform to model disease progression and individual demographic and healthcare-seeking behavior in India, and use an iterative, stochastic procedure to simulate health and economic outcomes over time. We find that scaling up access to piped water and improved sanitation could avert 43,352 (95% uncertainty range [UR] 42,201-44,504) diarrheal episodes and 68 (95% UR 62-74) diarrheal deaths per 100,000 under-5 children per year, compared with the baseline. We estimate a saving of (in 2013 US$) $357,788 (95% $345,509-$370,067) in out-of-pocket diarrhea treatment expenditure, and $1646 (95% UR $1603-$1689) in incremental value of insurance per 100,000 under-5 children per year over baseline. The health and financial benefits are highly progressive, i.e. they reach poorer households more. Thus, scaling up access to piped water and improved sanitation can lead to large and equitable reductions in the burden of childhood diarrheal diseases in India.

  10. Optimum ArFi laser bandwidth for 10nm node logic imaging performance

    NASA Astrophysics Data System (ADS)

    Alagna, Paolo; Zurita, Omar; Timoshkov, Vadim; Wong, Patrick; Rechtsteiner, Gregory; Baselmans, Jan; Mailfert, Julien

    2015-03-01

    Lithography process window (PW) and CD uniformity (CDU) requirements are being challenged with scaling across all device types. Aggressive PW and yield specifications put tight requirements on scanner performance, especially on focus budgets resulting in complicated systems for focus control. In this study, an imec N10 Logic-type test vehicle was used to investigate the E95 bandwidth impact on six different Metal 1 Logic features. The imaging metrics that track the impact of light source E95 bandwidth on performance of hot spots are: process window (PW), line width roughness (LWR), and local critical dimension uniformity (LCDU). In the first section of this study, the impact of increasing E95 bandwidth was investigated to observe the lithographic process control response of the specified logic features. In the second section, a preliminary assessment of the impact of lower E95 bandwidth was performed. The impact of lower E95 bandwidth on local intensity variability was monitored through the CDU of line end features and the LWR power spectral density (PSD) of line/space patterns. The investigation found that the imec N10 test vehicle (with OPC optimized for standard E95 bandwidth of300fm) features exposed at 200fm showed pattern specific responses, suggesting areas of potential interest for further investigation.

  11. Accounting for filter bandwidth improves the quantitative accuracy of bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Taylor, Shelley L.; Mason, Suzannah K. G.; Glinton, Sophie L.; Cobbold, Mark; Dehghani, Hamid

    2015-09-01

    Bioluminescence imaging is a noninvasive technique whereby surface weighted images of luminescent probes within animals are used to characterize cell count and function. Traditionally, data are collected over the entire emission spectrum of the source using no filters and are used to evaluate cell count/function over the entire spectrum. Alternatively, multispectral data over several wavelengths can be incorporated to perform tomographic reconstruction of source location and intensity. However, bandpass filters used for multispectral data acquisition have a specific bandwidth, which is ignored in the reconstruction. In this work, ignoring the bandwidth is shown to introduce a dependence of the recovered source intensity on the bandwidth of the filters. A method of accounting for the bandwidth of filters used during multispectral data acquisition is presented and its efficacy in increasing the quantitative accuracy of bioluminescence tomography is demonstrated through simulation and experiment. It is demonstrated that while using filters with a large bandwidth can dramatically decrease the data acquisition time, if not accounted for, errors of up to 200% in quantitative accuracy are introduced in two-dimensional planar imaging, even after normalization. For tomographic imaging, the use of this method to account for filter bandwidth dramatically improves the quantitative accuracy.

  12. Mahanaxar: quality of service guarantees in high-bandwidth, real-time streaming data storage

    SciTech Connect

    Bigelow, David; Bent, John; Chen, Hsing-Bung; Brandt, Scott

    2010-04-05

    Large radio telescopes, cyber-security systems monitoring real-time network traffic, and others have specialized data storage needs: guaranteed capture of an ultra-high-bandwidth data stream, retention of the data long enough to determine what is 'interesting,' retention of interesting data indefinitely, and concurrent read/write access to determine what data is interesting, without interrupting the ongoing capture of incoming data. Mahanaxar addresses this problem. Mahanaxar guarantees streaming real-time data capture at (nearly) the full rate of the raw device, allows concurrent read and write access to the device on a best-effort basis without interrupting the data capture, and retains data as long as possible given the available storage. It has built in mechanisms for reliability and indexing, can scale to meet arbitrary bandwidth requirements, and handles both small and large data elements equally well. Results from our prototype implementation shows that Mahanaxar provides both better guarantees and better performance than traditional file systems.

  13. A wide bandwidth CCD buffer memory system

    NASA Technical Reports Server (NTRS)

    Siemens, K.; Wallace, R. W.; Robinson, C. R.

    1978-01-01

    A prototype system was implemented to demonstrate that CCD's can be applied advantageously to the problem of low power digital storage and particularly to the problem of interfacing widely varying data rates. CCD shift register memories (8K bit) were used to construct a feasibility model 128 K-bit buffer memory system. Serial data that can have rates between 150 kHz and 4.0 MHz can be stored in 4K-bit, randomly-accessible memory blocks. Peak power dissipation during a data transfer is less than 7 W, while idle power is approximately 5.4 W. The system features automatic data input synchronization with the recirculating CCD memory block start address. System expansion to accommodate parallel inputs or a greater number of memory blocks can be performed in a modular fashion. Since the control logic does not increase proportionally to increase in memory capacity, the power requirements per bit of storage can be reduced significantly in a larger system.

  14. Remote driving with reduced bandwidth communication

    NASA Technical Reports Server (NTRS)

    Depiero, Frederick W.; Noell, Timothy E.; Gee, Timothy F.

    1993-01-01

    Oak Ridge National Laboratory has developed a real-time video transmission system for low bandwidth remote operations. The system supports both continuous transmission of video for remote driving and progressive transmission of still images. Inherent in the system design is a spatiotemporal limitation to the effects of channel errors. The average data rate of the system is 64,000 bits/s, a compression of approximately 1000:1 for the black and white National Television Standard Code video. The image quality of the transmissions is maintained at a level that supports teleoperation of a high mobility multipurpose wheeled vehicle at speeds up to 15 mph on a moguled dirt track. Video compression is achieved by using Laplacian image pyramids and a combination of classical techniques. Certain subbands of the image pyramid are transmitted by using interframe differencing with a periodic refresh to aid in bandwidth reduction. Images are also foveated to concentrate image detail in a steerable region. The system supports dynamic video quality adjustments between frame rate, image detail, and foveation rate. A typical configuration for the system used during driving has a frame rate of 4 Hz, a compression per frame of 125:1, and a resulting latency of less than 1s.

  15. Tunable pulsed narrow bandwidth light source

    DOEpatents

    Powers, Peter E.; Kulp, Thomas J.

    2002-01-01

    A tunable pulsed narrow bandwidth light source and a method of operating a light source are provided. The light source includes a pump laser, first and second non-linear optical crystals, a tunable filter, and light pulse directing optics. The method includes the steps of operating the pump laser to generate a pulsed pump beam characterized by a nanosecond pulse duration and arranging the light pulse directing optics so as to (i) split the pulsed pump beam into primary and secondary pump beams; (ii) direct the primary pump beam through an input face of the first non-linear optical crystal such that a primary output beam exits from an output face of the first non-linear optical crystal; (iii) direct the primary output beam through the tunable filter to generate a sculpted seed beam; and direct the sculpted seed beam and the secondary pump beam through an input face of the second non-linear optical crystal such that a secondary output beam characterized by at least one spectral bandwidth on the order of about 0.1 cm.sup.-1 and below exits from an output face of the second non-linear optical crystal.

  16. Low bandwidth robust controllers for flight

    NASA Technical Reports Server (NTRS)

    Biezad, Daniel J.; Chou, Hwei-Lan

    1992-01-01

    During the final reporting period (Jun. - Dec. 1992), analyses of the longitudinal and lateral flying qualities were made for propulsive-only flight control (POFC) of a Boeing 720 aircraft model. Performance resulting from compensators developed using Quantitative Feedback Theory (QFT) is documented and analyzed. This report is a first draft of a thesis to be presented by graduate student Hwei-Lan Chou. The final thesis will be presented to NASA when it is completed later this year. The latest landing metrics related to bandwidth criteria and based on the Neal-Smith approach to flying qualities prediction were used in developing performance criteria for the controllers. The compensator designs were tested on the NASA simulator and exhibited adequate performance for piloted flight. There was no significant impact of QFT on performance of the propulsive-only flight controllers in either the longitudinal or lateral modes of flight. This was attributed to the physical limits of thrust available and the engine rate of response, both of whiih severely limited the available bandwidth of the closed-loop system.

  17. Coherence bandwidth loss in transionospheric radio propagation

    NASA Technical Reports Server (NTRS)

    Rino, C. L.; Gonzalez, V. H.; Hessing, A. R.

    1980-01-01

    In this report a theoretical model is developed that predicts the single-point, two-frequency coherence function for transionospheric radio waves. The theoretical model is compared to measured complex frequency correlation coefficients using data from the seven equispaced, phase-coherent UHF signals transmitted by the Wideband satellite. The theory and data are in excellent agreement. The theory is critically dependent upon the power-law index, and the frequency coherence data clearly favor the comparatively small spectral indices that have been consistently measured from the wideband satellite phase data. A model for estimating the pulse delay jitter induced by the coherence bandwidth loss is also developed and compared with the actual delay jitter observed on synthesized pulses obtained from the Wideband UFH comb. The results are in good agreement with the theory. The results presented in this report, which are based on an asymptotic theory, are compared with the more commonly used quadratic theory. The model developed and validated in this report can be used to predict the effects of coherence bandwidth loss in disturbed nuclear environments. Simple formulas for the resultant pulse delay jitter are derived that can be used in predictive codes.

  18. Bandwidth and Noise in Spatiotemporally Modulated Mueller Matrix Polarimeters

    NASA Astrophysics Data System (ADS)

    Vaughn, Israel Jacob

    Polarimetric systems design has seen recent utilization of linear systems theory for system descriptions. Although noise optimal systems have been shown, bandwidth performance has not been addressed in depth generally and is particularly lacking for Mueller matrix (active) polarimetric systems. Bandwidth must be considered in a systematic way for remote sensing polarimetric systems design. The systematic approach facilitates both understanding of fundamental constraints and design of higher bandwidth polarimetric systems. Fundamental bandwidth constraints result in production of polarimetric "artifacts" due to channel crosstalk upon Mueller matrix reconstruction. This dissertation analyzes bandwidth trade-offs in spatio-temporal channeled Mueller matrix polarimetric systems. Bandwidth is directly related to the geometric positioning of channels in the Fourier (channel) space, however channel positioning for polarimetric systems is constrained both physically and by design parameters like domain separability. We present the physical channel constraints and the constraints imposed when the carriers are separable between space and time. Polarimetric systems are also constrained by noise performance, and there is a trade-off between noise performance and bandwidth. I develop cost functions which account for the trade-off between noise and bandwidth for spatio-temporal polarimetric systems. The cost functions allow a systems designer to jointly optimize systems with good bandwidth and noise performance. Optimization is implemented for a candidate spatio-temporal system design, and high temporal bandwidth systems resulting from the optimization are presented. Systematic errors which impact the bandwidth performance and mitigation strategies for these systematic errors are also presented. Finally, a portable imaging Mueller matrix system is built and analyzed based on the theoretical bandwidth analysis and system bandwidth optimization. Temporal bandwidth performance is

  19. Increased access to transplantation of highly sensitized patients under the new kidney allocation system. A single center experience.

    PubMed

    Colovai, Adriana I; Ajaimy, Maria; Kamal, Layla G; Masiakos, Peter; Chan, Shirley; Savchik, Christina; Lubetzky, Michelle; de Boccardo, Graciela; Courson, Alesa; Chokechanachaisakul, Attasit; Graham, Jay; Greenstein, Stuart; Kinkhabwala, Milan; Rocca, Juan; Akalin, Enver

    2017-03-01

    We aimed to investigate the impact of the new kidney allocation system (KAS) on the rate of transplantation of sensitized patients at our center. Pre-KAS and post-KAS intervals were Jan 1st to Dec 3rd 2014 and Jan 1st 2015 to Dec 3rd 2015, respectively. The number of deceased-donor crossmatches performed by flow cytometry increased from 715 pre-KAS to 1188 post-KAS. The percent of crossmatches performed for sensitized patients with calculated panel reactive antibody (cPRA)>0% increased from 19% pre-KAS to 26% post-KAS (p<0.0001). The number of deceased-donor kidney transplants performed at our center increased from 115 pre-KAS to 125 post-KAS (9% increase). There was a significant increase in the percentage of deceased-donor kidney transplants received by sensitized candidates (from 14% to 26% pre- and post-KAS, respectively; p<0.0001). The highest increase was seen in the patients with cPRA>98%, from 0% to 9%, followed by the group with cPRA 50-79%, from 5% to 8%. This increase was balanced by a decrease of 12% in the percentage of non-sensitized recipients, and a modest decrease of 1% in the group with cPRA 1-49%. In conclusion, transplant rate has increased in sensitized patients after KAS. The highest increase was observed among highly sensitized patients (cPRA>98%).

  20. Increasing equity of access to point-of-use water treatment products through social marketing and entrepreneurship: a case study in western Kenya.

    PubMed

    Freeman, Matthew C; Quick, Robert E; Abbott, Daniel P; Ogutu, Paul; Rheingans, Richard

    2009-09-01

    Point-of-use water chlorination reduces diarrhoea risk by 25-85%. Social marketing has expanded access to inexpensive sodium hypochlorite for water treatment, at a cost of less than US$0.01 per day, in Kenya. To increase product access, women's groups in western Kenya were trained to educate neighbours and sell health products to generate income. We evaluated this programme's impact on equity of access to water treatment products in a cross-sectional survey. We surveyed 487 randomly selected households in eight communities served by the women's groups. Overall, 20% (range 5-39%) of households in eight communities purchased and used chlorine, as confirmed by residual chlorine observed in stored water. Multivariate models using illiteracy and the poorest socioeconomic status as a referent showed that persons with at least some primary education (OR 2.5, 95% CI 1.8, 3.5) or secondary education (OR 5.4, 95% CI 1.6, 17.5) and persons in the four wealthiest quintiles (OR 2.5, 95% CI 1.0, 6.0) were more likely to chlorinate stored water. While this implementation model was associated with good product penetration and use, barriers to access to inexpensive water treatment remained among the very poor and less educated.

  1. Encouraging understanding or increasing prejudices: A cross-sectional survey of institutional influence on health personnel attitudes about refugee claimants' access to health care

    PubMed Central

    Rousseau, Cécile; Oulhote, Youssef; Ruiz-Casares, Mónica; Cleveland, Janet; Greenaway, Christina

    2017-01-01

    Background This paper investigates the personal, professional and institutional predictors of health institution personnel's attitudes regarding access to healthcare for refugee claimants in Canada. Methods In Montreal, the staff of five hospitals and two primary care centres (n = 1772) completed an online questionnaire documenting demographics, occupation, exposure to refugee claimant patients, and attitudes regarding healthcare access for refugee claimants. We used structural equations modeling to investigate the associations between professional and institutional factors with latent functions of positive and negative attitudes toward refugee's access to healthcare. Results Younger participants, social workers, participants from primary care centres, and from 1st migrant generation had the lowest scores of negative attitudes. Respondents who experienced contact with refugees had lower scores of negative attitudes (B = -14% standard deviation [SD]; 95% CI: -24, -4%). However, direct contact with refugees increased scores of negative attitudes in the institution with the most negative attitudes by 36% SD (95% CI: 1, 71%). Interpretation Findings suggest that institutions influence individuals’ attitudes about refugee claimants’ access to health care and that, in an institutional context of negative attitudes, contact with refugees may further confirm negative perceptions about this vulnerable group. PMID:28196129

  2. Sleep/doze controlled dynamic bandwidth allocation algorithms for energy-efficient passive optical networks.

    PubMed

    Dias, Maluge Pubuduni Imali; Wong, Elaine

    2013-04-22

    In this work, we present a comparative study of two just-in-time (JIT) dynamic bandwidth allocation algorithms (DBAs), designed to improve the energy-efficiency of the 10 Gbps Ethernet passive optical networks (10G-EPONs). The algorithms, termed just-in-time with varying polling cycle times (JIT) and just-in-time with fixed polling cycle times (J-FIT), are designed to achieve energy-savings when the idle time of an optical network unit (ONU) is less than the sleep-to-active transition time. This is made possible by a vertical-cavity surface-emitting laser (VCSEL) ONU that can transit into sleep or doze modes during its idle time. We evaluate the performance of the algorithms in terms of polling cycle time, power consumption, percentage of energy-savings, and average delay. The energy-efficiency of a VCSEL ONU that can transition into sleep or doze mode is compared to an always-ON distributed feedback (DFB) laser ONU. Simulation results indicate that both JIT and J-FIT DBA algorithms result in improved energy-efficiency whilst J-FIT performs better in terms of energy-savings at low network loads. The J-FIT DBA however, results in increased average delay in comparison to the JIT DBA. Nonetheless, this increase in average delay is within the acceptable range to support the quality of service (QoS) requirements of the next-generation access networks.

  3. Summation bandwidths at threshold in normal and hearing-impaired listeners.

    PubMed

    Higgins, M B; Turner, C W

    1990-12-01

    The bandwidths for summation at threshold were measured for subjects with normal hearing and subjects with sensorineural hearing loss. Thresholds in quiet and in the presence of a masking noise were measured for complex stimuli consisting of 1 to 40 pure-tone components spaced 20 Hz apart. The single component condition consisted of a single pure tone at 1100 Hz; additional components were added below this frequency, in a replication of the Gässler [Acustica 4, 408-414 (1954)] procedure. For the normal subjects, thresholds increased approximately 3 dB per doubling of bandwidth for signal bandwidths exceeding the critical bandwidth. This slope was less for the hearing-impaired subjects. Summation bandwidths, as estimated from two-line fits, were wider for the hearing-impaired than for the normal subjects. These findings provide evidence that hearing-impaired subjects integrate sound energy over a wider-than-normal frequency range for the detection of complex signals. A second experiment used stimuli similar to those of Spiegel [J. Acoust. Soc. Am. 66, 1356-1363 (1979)], and added components both above and below the frequency of the initial component. Using these stimuli, the slope of the threshold increase beyond the critical bandwidth was approximately 1.5 dB per doubling of bandwidth, thus replicating the Spiegel (1979) experiment. It is concluded that the differences between the Gässler (1954) and Spiegel (1979) studies were due to the different frequency content of the stimuli used in each study. Based upon the present results, it would appear that the slope of threshold increase is dependent upon the direction of signal expansion, and the size of the critical bands into which the signal is expanded.

  4. Statistical results describing the bandwidth and coherence coefficient of whistler mode waves using THEMIS waveform data

    NASA Astrophysics Data System (ADS)

    Gao, X.; Li, W.; Thorne, R. M.; Bortnik, J.; Angelopoulos, V.; Lu, Q.; Tao, X.; Wang, S.

    2014-11-01

    The bandwidths and coherence coefficients of lower band whistler mode waves are analyzed using Time History of Events and Macroscale Interactions during Substorms (THEMIS) waveform data for rising tones, falling tones, and hiss-like emissions separately. We also evaluate their dependences on the spatial location, electron density, the ratio of plasma frequency to local electron gyrofrequency (fpe/fce), and the wave amplitude. Our results show that the bandwidth normalized by the local electron gyrofrequency (fce) of rising and falling tones is very narrow (~0.01 fce), smaller than that of the hiss-like emissions (~0.025 fce). Meanwhile, the normalized bandwidth of discrete emissions gradually decreases with increasing wave amplitude, whereas that of hiss-like emissions increases slowly. The coherence coefficient of rising and falling tones is extremely large (~1), while the coherence coefficient of hiss-like emissions is smaller but is still larger than 0.5. For all categories of whistler mode waves, the normalized bandwidth increases at larger L shells. Furthermore, the normalized bandwidth is positively correlated with local fpe/fce but is inversely correlated with the electron density. Interactions between radiation belt electrons and whistler mode waves have been widely described by quasi-linear diffusion theory. Our results suggest that although quasi-linear theory is not entirely applicable for modeling electron interactions with rising and falling tones due to their narrow bandwidth and high coherence coefficient, it is suitable to treat wave-particle interactions between electrons and low-amplitude hiss-like emissions. Moreover, the correlations between the normalized bandwidth of chorus waves (especially the discrete emissions) and other parameters may provide insights for the generation mechanism of chorus waves.

  5. Application of Fiber-Optical Techniques in the Access Transmission and Backbone Transport of Mobile Networks

    NASA Astrophysics Data System (ADS)

    Hilt, Attila; Pozsonyi, László

    2012-09-01

    Fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In the last decade, there has also been an enormous increase of user data visible in mobile systems. The importance of fiber-optical techniques within the fixed transmission/transport networks of mobile systems is therefore inevitably increasing. This article summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in second-generation networks.

  6. Safe abortion information hotlines: An effective strategy for increasing women's access to safe abortions in Latin America.

    PubMed

    Drovetta, Raquel Irene

    2015-05-01

    This paper describes the implementation of five Safe Abortion Information Hotlines (SAIH), a strategy developed by feminist collectives in a growing number of countries where abortion is legally restricted and unsafe. These hotlines have a range of goals and take different forms, but they all offer information by telephone to women about how to terminate a pregnancy using misoprostol. The paper is based on a qualitative study carried out in 2012-2014 of the structure, goals and experiences of hotlines in five Latin American countries: Argentina, Chile, Ecuador, Peru and Venezuela. The methodology included participatory observation of activities of the SAIH, and in-depth interviews with feminist activists who offer these services and with 14 women who used information provided by these hotlines to induce their own abortions. The findings are also based on a review of materials obtained from the five hotline collectives involved: documents and reports, social media posts, and details of public demonstrations and statements. These hotlines have had a positive impact on access to safe abortions for women whom they help. Providing these services requires knowledge and information skills, but little infrastructure. They have the potential to reduce the risk to women's health and lives of unsafe abortion, and should be promoted as part of public health policy, not only in Latin America but also other countries. Additionally, they promote women's autonomy and right to decide whether to continue or terminate a pregnancy.

  7. GCAT-SEEKquence: genome consortium for active teaching of undergraduates through increased faculty access to next-generation sequencing data.

    PubMed

    Buonaccorsi, Vincent P; Boyle, Michael D; Grove, Deborah; Praul, Craig; Sakk, Eric; Stuart, Ash; Tobin, Tammy; Hosler, Jay; Carney, Susan L; Engle, Michael J; Overton, Barry E; Newman, Jeffrey D; Pizzorno, Marie; Powell, Jennifer R; Trun, Nancy

    2011-01-01

    To transform undergraduate biology education, faculty need to provide opportunities for students to engage in the process of science. The rise of research approaches using next-generation (NextGen) sequencing has been impressive, but incorporation of such approaches into the undergraduate curriculum remains a major challenge. In this paper, we report proceedings of a National Science Foundation-funded workshop held July 11-14, 2011, at Juniata College. The purpose of the workshop was to develop a regional research coordination network for undergraduate biology education (RCN/UBE). The network is collaborating with a genome-sequencing core facility located at Pennsylvania State University (University Park) to enable undergraduate students and faculty at small colleges to access state-of-the-art sequencing technology. We aim to create a database of references, protocols, and raw data related to NextGen sequencing, and to find innovative ways to reduce costs related to sequencing and bioinformatics analysis. It was agreed that our regional network for NextGen sequencing could operate more effectively if it were partnered with the Genome Consortium for Active Teaching (GCAT) as a new arm of that consortium, entitled GCAT-SEEK(quence). This step would also permit the approach to be replicated elsewhere.

  8. Bandwidth provisioning in infrastructure-based wireless networks employing directional antennas

    SciTech Connect

    Hasiviswanthan, Shiva; Zhao, Bo; Vasudevan, Sudarshan; Yrgaonkar, Bhuvan

    2009-01-01

    Motivated by the widespread proliferation of wireless networks employing directional antennas, we study the problem of provisioning bandwidth in such networks. Given a set of subscribers and one or more access points possessing directional antennas, we formalize the problem of orienting these antennas in two fundamental settings: (1) subscriber-centric, where the objective is to fairly allocate bandwidth among the subscribers and (2) provider-centric, where the objective is to maximize the revenue generated by satisfying the bandwidth requirements of subscribers. For both the problems, we first design algorithms for a network with only one access point working under the assumption that the number of antennas does not exceed the number of noninterfering channels. Using the well-regarded lexicographic max-min fair allocation as the objective for a subscriber-centric network, we present an optimum dynamic programming algorithm. For a provider-centric network, the allocation problem turns out to be NP-hard. We present a greedy heuristic based algorithm that guarantees almost half of the optimum revenue. We later enhance both these algorithms to operate in more general networks with multiple access points and no restrictions on the relative numbers of antennas and channels. A simulation-based evaluation using OPNET demonstrates the efficacy of our approaches and provides us further in insights into these problems.

  9. Do Loans Increase College Access and Choice? Examining the Introduction of Universal Student Loans. Working Paper 07-1

    ERIC Educational Resources Information Center

    Long, Bridget Terry

    2007-01-01

    The returns to college are substantial, including increased earnings and public benefits, such as better health and increased involvement in public service and giving. As a result, since the introduction of the Guaranteed Student Loan program in 1965 and the Pell Grant in 1972, the federal government has experimented with using financial aid to…

  10. Flexible power and bandwidth allocation in mobile satellites

    NASA Astrophysics Data System (ADS)

    Keyes, L. A.

    The introduction of L-band mobile communication services by spot beam satellites creates a payload design challenge due to uncertainty in the location and size of the new market to be served. A combination of payload technologies that allow a flexible allocation of power and bandwidth to any portion of the coverage area is described. Power flexibility is achieved by a novel combination of a low-level beam-forming network and a matrix power module which ensures equal sharing of power among individual amplifiers. This eliminates the loss of efficiency and increased mass when an amplifier associated with a beam must be over-designed to meet uncertainties in power distribution between beams. Flexibility in allocation of bandwidth to beams is achieved by intermediate frequency subdivision of the L-band service categories defined by ITU. These spectral subdivisions are assigned to beams by an IF interconnect matrix having beam ports and filter ports as inputs and outputs, respectively. Two such filter switch matrices are required, one for the inbound L-band to feeder link transponder, and one for the outbound feeder link to L-band transponder.

  11. Ptychography with broad-bandwidth radiation

    SciTech Connect

    Enders, B. Dierolf, M.; Stockmar, M.; Pfeiffer, F.; Cloetens, P.; Thibault, P.

    2014-04-28

    Ptychography, a scanning Coherent Diffractive Imaging (CDI) technique, has quickly gained momentum as a robust method to deliver quantitative images of extended specimens. A current conundrum for the development of X-ray CDI is the conflict between a need for higher flux to reach higher resolutions and the requirement to strongly filter the incident beam to satisfy the tight coherence prerequisite of the technique. Latest developments in algorithmic treatment of ptychographic data indicate that the technique is more robust than initially assumed, so that some experimental limitations can be substantially relaxed. Here, we demonstrate that ptychography can be conducted in conditions that were up to now considered insufficient, using a broad-bandwidth X-ray beam and an integrating scintillator-based detector. Our work shows the wide applicability of ptychography and paves the way to high-throughput, high-flux diffractive imaging.

  12. High bandwidth magnetically isolated signal transmission circuit

    NASA Technical Reports Server (NTRS)

    Repp, John Donald (Inventor)

    2005-01-01

    Many current electronic systems incorporate expensive or sensitive electrical components. Because electrical energy is often generated or transmitted at high voltages, the power supplies to these electronic systems must be carefully designed. Power supply design must ensure that the electrical system being supplied with power is not exposed to excessive voltages or currents. In order to isolate power supplies from electrical equipment, many methods have been employed. These methods typically involve control systems or signal transfer methods. However, these methods are not always suitable because of their drawbacks. The present invention relates to transmitting information across an interface. More specifically, the present invention provides an apparatus for transmitting both AC and DC information across a high bandwidth magnetic interface with low distortion.

  13. Bandwidth Efficient Wireless Digital Modem Developed

    NASA Technical Reports Server (NTRS)

    Kifle, Muli

    1999-01-01

    NASA Lewis Research Center has developed a digital approach for broadcasting highfidelity audio (nearly compact disk (CD) quality sound) in the commercial frequencymodulated (FM) broadcast band. This digital approach provides a means of achieving high data transmission rates with low hardware complexity--including low mass, size, and power consumption. Lewis has completed the design and prototype development of a bandwidth-efficient digital modem (modulator and demodulator) that uses a spectrally efficient modulation scheme: 16-ary rectangular quadrature amplitude modulation, or 16- ary QAM. The digital implementation is based strictly on inexpensive, commercial off-theshelf digital signal processing (DSP) hardware to perform up and down conversions and pulse shaping. The digital modem transmits data at rates up to 76 kilobits per second (kbps), which is almost 3 times faster than standard 28.8-kbps telephone modems. In addition, the modem offers improved power and spectral performance, flexible operation, and low-cost implementation.

  14. Optimal filter bandwidth for pulse oximetry.

    PubMed

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  15. Optimal filter bandwidth for pulse oximetry

    NASA Astrophysics Data System (ADS)

    Stuban, Norbert; Niwayama, Masatsugu

    2012-10-01

    Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

  16. Novel high-bandwidth bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, Michael S.; Laycock, Leslie C.; Archer, Nick J.

    2004-12-01

    Adaptive Optics (AO) is a critical underpinning technology for future laser delivery (including free-space optical communications), target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS Advanced Technology Centre is developing multi-element bimorph deformable mirrors for such an applications. Our initial designs were based on a standard construction and exhibited a resonant frequency of 1kHz with a maximum stroke of +/-20μm for an active aperture of 50mm. These devices were limited by the necessity to have a 'dead space' between the inner active area and the mirror boundary; this ensured that both the requirements for the stroke and the fixed boundary conditions could be met simultaneously. However, there was a significant penalty to pay in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. In a series of iteration steps, we have created novel mounting arrangements that reduce dead space and thus provide the optimum trade-off between bandwidth and stroke. These schemes include supporting the mirror from underneath, rather than at its edge. As a result, models of 60mm active diameter mirrors predict a resonance in excess of 5kHz, combined with a maximum stroke greater than +/-40μm. This paper will discuss a number of different mirror designs and present experimental results for recently assembled devices.

  17. Dynamic Bandwidth Allocation Algorithm with Fairness in 1G/10G Coexistence EPON System

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaki; Takemoto, Michiya; Takahashi, Akira; Shimokasa, Kiyoshi

    Gigabit Ethernet Passive Optical Networks (GE-PON) systems have been deployed widely as a broadband access solution for the optical access network, the so-called FTTx networks. 10 Gigabit EPON (10G-EPON) is about to be standardizing by a task force (802.3av). To provide the next FTTx solution with 10G-EPON systems, one of the key technologies is how to migrate from 1G-based to 10G-based. In this paper, we present Dynamic Bandwidth Allocation (DBA) algorithm which considered a fair policy for 1G/10G coexistence EPON system to achieve a smooth migration.

  18. Fiber in access technologies and network convergence: an opportunity for optical integration

    NASA Astrophysics Data System (ADS)

    Ghiggino, Pierpaolo C.

    2008-11-01

    Broadband networks are among the fastest growing segment in telecom. The initial and still very significant push originated with xDSL technologies and indeed a significant amount of research and development is still occurring in this field with impressive results and allowing for a remarkable use of the installed copper infrastructure way beyond its originally planned bandwidth capabilities. However it is clear that ultimately a more suitable fiber based infrastructure will be needed in order to reduce both operational and network technology costs. Such cost reduction in inevitable as the added value to end users is only related to services and these cannot be priced outside a sensible window, whilst the related bandwidth increase is much more dramatic and its huge variability must be met with little or no cost impact by the network and its operation. Fiber in access has indeed the potential to cope with a huge bandwidth demand for many years to come as its inherent bandwidth capabilities are only just tapped by current service requirements. However the whole technology supply chain must follow in line. In particular optical technology must brace itself to cope with the required much larger deployment and greater cost effectiveness, whilst at the same time deliver performance suitable to the bandwidth increase offered in the longer term by the fiber medium. This paper looks at this issues and debates the opportunities for a new class of optical devices making use of the progress in optical integration

  19. Using a 1.2 GHz bandwidth reflective semiconductor optical amplifier with seeding light by 64-quadrature amplitude modulation orthogonal frequency division multiplexing modulation to achieve a 10-gbits/s upstream rate in long-reach passive optical network access

    NASA Astrophysics Data System (ADS)

    Yeh, Chien-Hung; Chen, Hsing-Yu; Chow, Chi-Wai; Wu, Yu-Fu

    2012-01-01

    We use a commercially available 1.2 GHz bandwidth reflective semiconductor optical amplifier (RSOA)--based optical network unit (ONU) to achieve 10-gbits/s upstream traffic for an optical orthogonal frequency division multiplexing (OFDM) long-reach passive optical network (LR-PON). This is the first time the 64--quadrature amplitude modulation (QAM) OFDM format has been applied to RSOA-ONU to achieve a 75 km fiber transmission length. In the proposed LR-PON, the upstream power penalty of 5.2 dB at the bit error rate of 3.8×10-3 is measured by using a 64-QAM OFDM modulation after the 75 km fiber transmission without dispersion compensation.

  20. Increasing Access for Economically Disadvantaged Students: The NSF/CSEM & S-STEM Programs at Louisiana State University

    ERIC Educational Resources Information Center

    Wilson, Zakiya S.; Iyengar, Sitharama S.; Pang, Su-Seng; Warner, Isiah M.; Luces, Candace A.

    2012-01-01

    Increasing college degree attainment for students from disadvantaged backgrounds is a prominent component of numerous state and federal legislation focused on higher education. In 1999, the National Science Foundation (NSF) instituted the "Computer Science, Engineering, and Mathematics Scholarships" (CSEMS) program; this initiative was designed to…

  1. Universal Design for Learning: Preparing Secondary Education Teachers in Training to Increase Academic Accessibility of High School English Learners

    ERIC Educational Resources Information Center

    Lopes-Murphy, Solange

    2012-01-01

    Although the concept of universal design for learning (UDL) is well understood in the world of architecture and in the area of special education, its use to increase the academic performance of high school English learners (ELs) is not widely explored. To reduce this void, this article presents an overview of the UDL concept and its principles,…

  2. Bandwidth enhancement using Polymeric Grid Array Antenna for millimeter-wave application

    NASA Astrophysics Data System (ADS)

    Muhamad, Wan Asilah Wan; Ngah, Razali; Jamlos, Mohd Faizal; Soh, Ping Jack; Ali, Mohd Tarmizi

    2017-01-01

    A new grid array antenna designed on a polymeric polydimethylsiloxane (PDMS) substrate is presented. A good relative permittivity of the PDMS substrate increases the antenna bandwidth. The PDMS surface is also hardened to protect the proposed grid array antenna's radiating element. A SMA coaxial connector is used to feed the 36 × 35 mm2 antenna from its bottom. A bandwidth enhancement of 72.1% is obtained compared to conventional antenna. Besides, its efficiency is increased up to 70%. The simulated and measured results agreed well and the proposed antenna is validated to suit millimeter-wave applications.

  3. Compact antenna arrays with wide bandwidth and low sidelobe levels

    SciTech Connect

    Strassner, II, Bernd H.

    2014-09-09

    Highly efficient, low cost, easily manufactured SAR antenna arrays with lightweight low profiles, large instantaneous bandwidths and low SLL are disclosed. The array topology provides all necessary circuitry within the available antenna aperture space and between the layers of material that comprise the aperture. Bandwidths of 15.2 GHz to 18.2 GHz, with 30 dB SLLs azimuthally and elevationally, and radiation efficiencies above 40% may be achieved. Operation over much larger bandwidths is possible as well.

  4. An ultrawide-bandwidth single-sideband modulator for terahertz frequencies

    NASA Astrophysics Data System (ADS)

    Meijer, A. S.; Berden, G.; Arslanov, D. D.; Ozerov, M.; Jongma, R. T.; van der Zande, W. J.

    2016-11-01

    Wireless high-speed data communication using terahertz (THz) carrier frequencies is becoming reality with data rates beyond 100 Gbit s-1. Many of the mobile applications use internet access and require that THz wireless base stations are connected to a global network, such as the radio-over-fibre network. We present the realization of an ultrawide bandwidth THz optical single-sideband (OSSB) modulator for converting (free-space) THz signals to THz optical modulations with an increased spectral efficiency. THz OSSB will mitigate chromatic dispersion-induced propagation losses in optical fibres and support digital modulation schemes. We demonstrate THz OSSB for free-space radiation between 0.3 and 1.0 THz using a specially designed dichroic beamsplitter for signal and carrier, and a planar light-wave circuit with multimode interference structures. This arrangement of optical elements mimics the Hartley single-sideband modulator for electronics signals and accomplishes the required Hilbert transform without any frequency-dependent tuning element over an ultrawide THz spectrum.

  5. Increasing access to fresh produce by pairing urban farms with corner stores: a case study in a low-income urban setting

    PubMed Central

    Gudzune, Kimberly A.; Welsh, Claire; Lane, Elisa; Chissell, Zach; Steeves, Elizabeth Anderson; Gittelsohn, Joel

    2015-01-01

    Objective Our objective was to pilot collaborations between two urban farms with two corner stores to increase access to fresh produce in low-income neighborhoods. Design We conducted a pre-post evaluation of two farm-store collaborations using quantitative distribution and sales data. Using semi-structured interviews, we qualitatively assessed feasibility of implementation and collaboration acceptability to farmers and storeowners. Setting Low-income urban neighborhoods in Baltimore, MD in 2012 Subjects Pair #1 included a ½-acre urban farm with a store serving local residents and was promoted by the neighborhood association. Pair #2 included a 6-acre urban farm with a store serving bus commuters. Results Produce was delivered all 9 weeks in both pairs. Pair #1 produced a significant increase in the mean number of produce varieties carried in the store by 11.3 (p<0.01) and sold 86% of all items delivered. Pair #2 resulted in a non-significant increase in number of produce varieties carried by 2.2 (p=0.44) and sold 63% of all items delivered. Conclusions Our case study suggests that pairing urban farms with corner stores for produce distribution may be feasible, and could be a new model to increase access to fruits and vegetables among low-income urban neighborhoods. For future programs to be successful, strong community backing may be vital to support produce sales. PMID:25649045

  6. Social value of high bandwidth networks: creative performance and education.

    PubMed

    Mansell, Robin; Foresta, Don

    2016-03-06

    This paper considers limitations of existing network technologies for distributed theatrical performance in the creative arts and for symmetrical real-time interaction in online learning environments. It examines the experience of a multidisciplinary research consortium that aimed to introduce a solution to latency and other network problems experienced by users in these sectors. The solution builds on the Multicast protocol, Access Grid, an environment supported by very high bandwidth networks. The solution is intended to offer high-quality image and sound, interaction with other network platforms, maximum user control of multipoint transmissions, and open programming tools that are flexible and modifiable for specific uses. A case study is presented drawing upon an extended period of participant observation by the authors. This provides a basis for an examination of the challenges of promoting technological innovation in a multidisciplinary project. We highlight the kinds of technical advances and cultural and organizational changes that would be required to meet demanding quality standards, the way a research consortium planned to engage in experimentation and learning, and factors making it difficult to achieve an open platform that is responsive to the needs of users in the creative arts and education sectors.

  7. Increasing Tumor Accessibility with Conjugatable Disulfide-Bridged Tumor-Penetrating Peptides for Cancer Diagnosis and Treatment

    PubMed Central

    Kotamraju, Venkata Ramana; Sharma, Shweta; Kolhar, Poornima; Agemy, Lilach; Pavlovich, James; Ruoslahti, Erkki

    2015-01-01

    Tumor-homing peptides with tissue-penetrating properties increase the efficacy of targeted cancer therapy by delivering an anticancer agent to the tumor interior. LyP-1 (CGNKRTRGC) and iRGD (CRGDKGPDC) are founding members of this class of peptides. The presence of the cysteines forming the cyclizing disulfide bond complicates conjugation of these peptides with other molecules, such as drugs. Here, we report the synthesis of conjugatable disulfide-bridged peptides and their conjugation to biologically important molecules. We have synthesized the LyP-1, iRGD, and CRGDC (GACRGDCLGA) peptides with a cysteine or maleimidohexanoic acid added externally at N-terminus of the sequences. Subsequent conjugation to payloads yielded stable compounds in which the tumor-homing properties of the peptide and the biological activity of the payload were retained. PMID:27385913

  8. High-bandwidth detection of short DNA in nanopipettes.

    PubMed

    Fraccari, Raquel L; Carminati, Marco; Piantanida, Giacomo; Leontidou, Tina; Ferrari, Giorgio; Albrecht, Tim

    2016-12-12

    Glass or quartz nanopipettes have found increasing use as tools for studying the biophysical properties of DNA and proteins, and as sensor devices. The ease of fabrication, favourable wetting properties and low capacitance are some of the inherent advantages, for example compared to more conventional, silicon-based nanopore chips. Recently, we have demonstrated high-bandwidth detection of double-stranded (ds) DNA with microsecond time resolution in nanopipettes, using custom-designed electronics. The electronics design has now been refined to include more sophisticated control features, such as integrated bias reversal and other features. Here, we exploit these capabilities and probe the translocation of short dsDNA in the 100 bp range, in different electrolytes. Single-stranded (ss) DNA of similar length are in use as capture probes, so label-free detection of their ds counterparts could therefore be of relevance in disease diagnostics.

  9. Familial Alzheimer’s mutations within APPTM increase Aβ42 production by enhancing accessibility of ɛ-cleavage site

    NASA Astrophysics Data System (ADS)

    Chen, Wen; Gamache, Eric; Rosenman, David J.; Xie, Jian; Lopez, Maria M.; Li, Yue-Ming; Wang, Chunyu

    2014-01-01

    The high Aβ42/Aβ40 production ratio is a hallmark of familial Alzheimer’s disease, which can be caused by mutations in the amyloid precursor protein (APP). The C-terminus of Aβ is generated by γ-secretase cleavage within the transmembrane domain of APP (APPTM), a process that is primed by an initial ɛ-cleavage at either T48 or L49, resulting in subsequent production of Aβ42 or Aβ40, respectively. Here we solve the dimer structures of wild-type APPTM (AAPTM WT) and mutant APPTM (FAD mutants V44M) with solution NMR. The right-handed APPTM helical dimer is mediated by GXXXA motif. From the NMR structural and dynamic data, we show that the V44M and V44A mutations can selectively expose the T48 site by weakening helical hydrogen bonds and increasing hydrogen-deuterium exchange rate (kex). We propose a structural model in which FAD mutations (V44M and V44A) can open the T48 site γ-secretase for the initial ɛ-cleavage, and consequently shift cleavage preference towards Aβ42.

  10. Improved access to histopathology using a digital system could increase the organ donor pool and improve allocation.

    PubMed

    Neil, Desley A H; Roberts, Ian S D; Bellamy, Christopher O C; Wigmore, Stephen J; Neuberger, James M

    2014-08-01

    Improvements in digital slide scanners have reached a stage that digital whole slide images (WSIs) can be used for diagnostic purposes. A digital system for histopathology, analogous to the systems used in radiology, would allow the establishment of networks of subspecialist histopathologists to provide a regional, national or even international rota to support out of hours histopathology for emergency frozen sections, urgent paraffin sections and to generally improve efficiencies with the provision of histopathology services. Such a system would promote appropriate organ utilization by allowing rapid characterization of unexpected lesions in the donor to determine whether donation should occur and further characterization of the organ, such as the degree of fibrosis in the kidney or steatosis in the liver, to determine whether the organ should be used. If introduced across Europe, this would promote safe and effective exchange of organs and support a cost efficient use of pathologist expertise. This review article outlines current issues with the provision of an urgent out of hours histopathology service and focuses on how such a service has the potential to increase organ donors, improve allocation, sharing and the use of available donor organs.

  11. High bandwidth optical coherent transient true-time delay

    NASA Astrophysics Data System (ADS)

    Reibel, Randy Ray

    An approach to reaching high bandwidth optical coherent transient (OCT) true-time delay (TTD) is described and demonstrated in this thesis. Utilizing the stimulated photon echo process in rare-earth ion doped crystals, such as Tm3+:YAG, TTD of optical signals with bandwidths >20 GHz and high time bandwidth products >104 are possible. TTD regenerators using OCT's have been demonstrated at low bandwidths (<40 MHz) showing picosecond delay resolutions with microsecond delays. With the advent of high bandwidth chirped lasers and high bandwidth electro-optic phase modulators, OCT TTD of broadband optical signals is now possible in the multi-gigahertz regime. To achieve this goal, several theoretical and technical aspects had to be explored. Theoretical discussions and numerical simulations are given using the Maxwell-Bloch equations with arbitrary phase. These simulations show good signal fidelity and high (60%) power efficiencies on echoes produced from gratings programmed with linear frequency chirps. New approaches for programming spectral gratings were also examined that utilized high bandwidth electro-optic modulators. In this technique, the phase modulation sidebands on an optical carrier are linearly chirped, creating an analog to the common linear frequency chirp. This approach allows multi-gigahertz true-time delay spectral grating programming. These new programming approaches are examined and characterized, both through simulation and experiment. A high bandwidth injection locked amplifier, based on semiconductor diode lasers, had to be developed and characterized to boost optical powers from both electro-optic phase modulators as well as chirped lasers. The injection locking system in conjunction with acousto-optic modulators were used in high bandwidth TTD demonstrations in Tm3+:YAG. Ultimately, high bandwidth binary phase shift keyed probe pulses were used in a demonstration of broadband true-time delay at a data rate of 1 GBit/s. The techniques, theory

  12. Schottky Heterodyne Receivers With Full Waveguide Bandwidth

    NASA Technical Reports Server (NTRS)

    Hesler, Jeffrey; Crowe, Thomas

    2011-01-01

    Compact THz receivers with broad bandwidth and low noise have been developed for the frequency range from 100 GHz to 1 THz. These receivers meet the requirements for high-resolution spectroscopic studies of planetary atmospheres (including the Earth s) from spacecraft, as well as airborne and balloon platforms. The ongoing research is significant not only for the development of Schottky mixers, but also for the creation of a receiver system, including the LO chain. The new receivers meet the goals of high sensitivity, compact size, low total power requirement, and operation across complete waveguide bands. The exceptional performance makes these receivers ideal for the broader range of scientific and commercial applications. These include the extension of sophisticated test and measurement equipment to 1 THz and the development of low-cost imaging systems for security applications and industrial process monitoring. As a particular example, a WR-1.9SHM (400-600 GHz) has been developed (see Figure 1), with state-of-the-art noise temperature ranging from 1,000-1,800 K (DSB) over the full waveguide band. Also, a Vector Network Analyzer extender has been developed (see Figure 2) for the WR1.5 waveguide band (500 750 GHz) with 100-dB dynamic range.

  13. What Works? Strategies to Increase Reproductive, Maternal and Child Health in Difficult to Access Mountainous Locations: A Systematic Literature Review

    PubMed Central

    Byrne, Abbey; Hodge, Andrew; Jimenez-Soto, Eliana; Morgan, Alison

    2014-01-01

    Background Geography poses serious challenges to delivery of health services and is a well documented marker of inequity. Maternal, newborn and child health (MNCH) outcomes are poorer in mountainous regions of low and lower-middle income countries due to geographical inaccessibility combined with other barriers: poorer quality services, persistent cultural and traditional practices and lower socioeconomic and educational status. Reaching universal coverage goals will require attention for remote mountain settings. This study aims to identify strategies to address barriers to reproductive MNCH (RMNCH) service utilisation in difficult-to-reach mountainous regions in low and lower-middle income settings worldwide. Methods A systematic literature review drawing from MEDLINE, Web of Science, Scopus, Google Scholar, and Eldis. Inclusion was based on; testing an intervention for utilisation of RMNCH services; remote mountain settings of low- and lower-middle income countries; selected study designs. Studies were assessed for quality and analysed to present a narrative review of the key themes. Findings From 4,130 articles 34 studies were included, from Afghanistan, Bolivia, Ethiopia, Guatemala, Indonesia, Kenya, Kyrgyzstan, Nepal, Pakistan, Papua New Guinea and Tajikistan. Strategies fall into four broad categories: improving service delivery through selected, trained and supported community health workers (CHWs) to act alongside formal health workers and the distribution of critical medicines to the home; improving the desirability of existing services by addressing the quality of care, innovative training and supervision of health workers; generating demand by engaging communities; and improving health knowledge for timely care-seeking. Task shifting, strengthened roles of CHWs and volunteers, mobile teams, and inclusive structured planning forums have proved effective. Conclusions The review highlights where known evidence-based strategies have increased the

  14. Increased depression-like behaviors with dysfunctions in the stress axis and the reward center by free access to highly palatable food.

    PubMed

    Park, E; Kim, J Y; Lee, J-H; Jahng, J W

    2014-03-14

    This study was conducted to examine the behavioral consequences of unlimited consumption of highly palatable food (HPF) and investigate its underlying neural mechanisms. Male Sprague-Dawley rats had free access to chocolate cookie rich in fat (HPF) in addition to ad libitum chow and the control group received chow only. Rats were subjected to behavioral tests during the 2nd week of food condition; i.e. ambulatory activity test on the 8th, elevated plus maze test (EPM) on the 10th and forced swim test (FST) on the 14th day of food condition. After 8 days of food condition, another group of rats were placed in a restraint box and tail bloods were collected at 0, 20, 60, and 120 time points during 2h of restraint period, used for the plasma corticosterone assay. At the end of restraint session, rats were sacrificed and the tissue sections of the nucleus accumbens (NAc) were processed for c-Fos immunohistochemistry. Ambulatory activities and the scores of EPM were not significantly affected by unlimited cookie consumption. However, immobility duration during FST was increased, and swim decreased, in the rats received free cookie access compared with control rats. Stress-induced corticosterone increase was exaggerated in cookie-fed rats, while the stress-induced c-Fos expression in the NAc was blunted, compared to control rats. Results suggest that free access to HPF may lead to the development of depression-like behaviors in rats, likely in relation with dysfunctions in the hypothalamic-pituitary-adrenal axis and the reward center.

  15. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats.

    PubMed

    Li, Hao; Liu, Wenzhong; Zhang, Hao F

    2015-10-01

    Abstract. Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10  μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  16. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    NASA Astrophysics Data System (ADS)

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-10-01

    Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

  17. Corrugated structure insertion for extending the SASE bandwidth up to 3% at the European XFEL

    NASA Astrophysics Data System (ADS)

    Zagorodnov, I.; Feng, G.; Limberg, T.

    2016-11-01

    The usage of x-ray free electron laser (XFEL) in femtosecond nanocrystallography involves sequential illumination of many small crystals of arbitrary orientation. Hence a wide radiation bandwidth will be useful in order to obtain and to index a larger number of Bragg peaks used for determination of the crystal orientation. Considering the baseline configuration of the European XFEL in Hamburg, and based on beam dynamics simulations, we demonstrate here that the usage of corrugated structures allows for a considerable increase in radiation bandwidth. Data collection with a 3% bandwidth, a few microjoule radiation pulse energy, a few femtosecond pulse duration, and a photon energy of 5.4 keV is possible. For this study we have developed an analytical modal representation of the short-range wake function of the flat corrugated structures for arbitrary offsets of the source and the witness particles.

  18. Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

    PubMed Central

    Li, Hao; Liu, Wenzhong; Zhang, Hao F.

    2015-01-01

    Abstract. Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10  μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications. PMID:26502233

  19. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  20. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  1. Continuous control of phase-locked-loop bandwidth

    NASA Technical Reports Server (NTRS)

    Motal, G. W.; Vanelli, J. C.

    1980-01-01

    Tracking loop filter with continuous bandwidth control smooths transition from wide to narrow band. Circuit was designed for Space Shuttle where bandwidth varied between 320 Hz for acquisition and 20 Hz for tracking. Field-effect transitor (FET) acts as voltage controlled variable resistance, changing time constant of filter between phase detector and voltage-controlled oscillator in phase-locked loop.

  2. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bandwidth and emission limitations. 101.809... SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and emission... authorized to employ only amplitude modulated or frequency modulated emission for radiotelephony....

  3. Optimal Bandwidth Selection in Observed-Score Kernel Equating

    ERIC Educational Resources Information Center

    Häggström, Jenny; Wiberg, Marie

    2014-01-01

    The selection of bandwidth in kernel equating is important because it has a direct impact on the equated test scores. The aim of this article is to examine the use of double smoothing when selecting bandwidths in kernel equating and to compare double smoothing with the commonly used penalty method. This comparison was made using both an equivalent…

  4. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  5. 47 CFR 101.809 - Bandwidth and emission limitations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bandwidth and emission limitations. 101.809 Section 101.809 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Local Television Transmission Service § 101.809 Bandwidth and...

  6. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and emission... within the frequency limits of the assigned channel. (c) The emission designator shall be specified in... 47 Telecommunication 4 2010-10-01 2010-10-01 false Authorized bandwidth and emission...

  7. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 4 2014-10-01 2014-10-01 false Authorized bandwidth and emission designator. 78.104 Section 78.104 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and...

  8. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Authorized bandwidth and emission designator. 78.104 Section 78.104 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and...

  9. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 4 2013-10-01 2013-10-01 false Authorized bandwidth and emission designator. 78.104 Section 78.104 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and...

  10. 47 CFR 78.104 - Authorized bandwidth and emission designator.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Authorized bandwidth and emission designator. 78.104 Section 78.104 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES CABLE TELEVISION RELAY SERVICE Technical Regulations § 78.104 Authorized bandwidth and...

  11. Avoiding bandwidth collapse in long chains of coupled optical microresonators.

    PubMed

    Mookherjea, Shayan; Schneider, Mark A

    2011-12-01

    Coupled photonic oscillators and resonators are sensitive to unavoidable nanoscale disorder, and localization in periodic structures induced by disorder leads eventually to a complete collapse of the bandwidth, which is generally considered problematic for device applications. Here, we investigate the dependence of bandwidth collapse on the interresonator coupling coefficient, a parameter controllable by lithography or device operation.

  12. Increasing cellulose accessibility is more important than removing lignin: a comparison of cellulose solvent-based lignocellulose fractionation and soaking in aqueous ammonia.

    PubMed

    Rollin, Joseph A; Zhu, Zhiguang; Sathitsuksanoh, Noppadon; Zhang, Y-H Percival

    2011-01-01

    While many pretreatments attempt to improve the enzymatic digestibility of biomass by removing lignin, this study shows that improving the surface area accessible to cellulase is a more important factor for achieving a high sugar yield. Here we compared the pretreatment of switchgrass by two methods, cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) and soaking in aqueous ammonia (SAA). Following pretreatment, enzymatic hydrolysis was conducted at two cellulase loadings, 15 filter paper units (FPU)/g glucan and 3 FPU/g glucan, with and without BSA blocking of lignin absorption sites. The hydrolysis results showed that the lignin remaining after SAA had a significant negative effect on cellulase performance, despite the high level of delignification achieved with this pretreatment. No negative effect due to lignin was detected for COSLIF-treated substrate. SEM micrographs, XRD crystallinity measurements, and cellulose accessibility to cellulase (CAC) determinations confirmed that COSLIF fully disrupted the cell wall structure, resulting in a 16-fold increase in CAC, while SAA caused a 1.4-fold CAC increase. A surface plot relating the lignin removal, CAC, and digestibility of numerous samples (both pure cellulosic substrates and lignocellulosic materials pretreated by several methods) was also developed to better understand the relative impacts of delignification and CAC on glucan digestibility.

  13. Power and Efficiency Optimized in Traveling-Wave Tubes Over a Broad Frequency Bandwidth

    NASA Technical Reports Server (NTRS)

    Wilson, Jeffrey D.

    2001-01-01

    A traveling-wave tube (TWT) is an electron beam device that is used to amplify electromagnetic communication waves at radio and microwave frequencies. TWT's are critical components in deep space probes, communication satellites, and high-power radar systems. Power conversion efficiency is of paramount importance for TWT's employed in deep space probes and communication satellites. A previous effort was very successful in increasing efficiency and power at a single frequency (ref. 1). Such an algorithm is sufficient for narrow bandwidth designs, but for optimal designs in applications that require high radiofrequency power over a wide bandwidth, such as high-density communications or high-resolution radar, the variation of the circuit response with respect to frequency must be considered. This work at the NASA Glenn Research Center is the first to develop techniques for optimizing TWT efficiency and output power over a broad frequency bandwidth (ref. 2). The techniques are based on simulated annealing, which has the advantage over conventional optimization techniques in that it enables the best possible solution to be obtained (ref. 3). Two new broadband simulated annealing algorithms were developed that optimize (1) minimum saturated power efficiency over a frequency bandwidth and (2) simultaneous bandwidth and minimum power efficiency over the frequency band with constant input power. The algorithms were incorporated into the NASA coupled-cavity TWT computer model (ref. 4) and used to design optimal phase velocity tapers using the 59- to 64-GHz Hughes 961HA coupled-cavity TWT as a baseline model. In comparison to the baseline design, the computational results of the first broad-band design algorithm show an improvement of 73.9 percent in minimum saturated efficiency (see the top graph). The second broadband design algorithm (see the bottom graph) improves minimum radiofrequency efficiency with constant input power drive by a factor of 2.7 at the high band edge (64

  14. Challenges of future converged access and metro networks

    NASA Astrophysics Data System (ADS)

    Breuer, D.; Hülsermann, R.; Lange, C.; Weis, E.

    2010-01-01

    Steadily increasing customer demand for more and more bandwidth in excess of 100 Mbit/s per subscriber, new technical options and a strong competitive environment drive the evolution of today's telecommunication networks, particularly in the access network. The physical properties of fibers such as very low loss and almost unlimited bandwidth allow for high bit rate long distance transmission in future access networks compared to the conventional copper based access networks in place today. In future this is expected to lead to much larger service areas which are served from one central office and to a significant reduction of central offices of today's infrastructure facilitating a converged metro-access architecture. One driver for this network consolidation is the need for significant operational expenditure (OpEx) savings which are expected due to reduction of active equipment and footprint. But also the changes from today's "service oriented" network design, where each service is almost realized on a new platform, towards an open standardized multi-layer Next Generation Network where all services will be delivered over a common infrastructure will lead to significant challenges in the network infrastructure.

  15. Adaptive Code Division Multiple Access Protocol for Wireless Network-on-Chip Architectures

    NASA Astrophysics Data System (ADS)

    Vijayakumaran, Vineeth

    Massive levels of integration following Moore's Law ushered in a paradigm shift in the way on-chip interconnections were designed. With higher and higher number of cores on the same die traditional bus based interconnections are no longer a scalable communication infrastructure. On-chip networks were proposed enabled a scalable plug-and-play mechanism for interconnecting hundreds of cores on the same chip. Wired interconnects between the cores in a traditional Network-on-Chip (NoC) system, becomes a bottleneck with increase in the number of cores thereby increasing the latency and energy to transmit signals over them. Hence, there has been many alternative emerging interconnect technologies proposed, namely, 3D, photonic and multi-band RF interconnects. Although they provide better connectivity, higher speed and higher bandwidth compared to wired interconnects; they also face challenges with heat dissipation and manufacturing difficulties. On-chip wireless interconnects is one other alternative proposed which doesn't need physical interconnection layout as data travels over the wireless medium. They are integrated into a hybrid NOC architecture consisting of both wired and wireless links, which provides higher bandwidth, lower latency, lesser area overhead and reduced energy dissipation in communication. However, as the bandwidth of the wireless channels is limited, an efficient media access control (MAC) scheme is required to enhance the utilization of the available bandwidth. This thesis proposes using a multiple access mechanism such as Code Division Multiple Access (CDMA) to enable multiple transmitter-receiver pairs to send data over the wireless channel simultaneously. It will be shown that such a hybrid wireless NoC with an efficient CDMA based MAC protocol can significantly increase the performance of the system while lowering the energy dissipation in data transfer. In this work it is shown that the wireless NoC with the proposed CDMA based MAC protocol

  16. Uplink Access Schemes for LTE-Advanced

    NASA Astrophysics Data System (ADS)

    Liu, Le; Inoue, Takamichi; Koyanagi, Kenji; Kakura, Yoshikazu

    The 3GPP LTE-Advanced has been attracting much attention recently, where the channel bandwidth would be beyond the maximum bandwidth of LTE, 20MHz. In LTE, single carrier-frequency division multiple access (SC-FDMA) was accepted as the uplink access scheme due to its advantage of very low cubic metric (CM). For LTE-A wideband transmission, multicarrier access would be more effective than single carrier access to make use of multi-user diversity and can maintain the physical channel structure of LTE, where the control information is transmitted on the edges of each 20MHz. In this paper, we discuss the access schemes in bandwidth under 20MHz as well as over 20MHz. In the case of bandwidth under 20MHz, we propose the access schemes allowing discontinuous resource allocation to enhance average throughput while maintaining cell-edge user throughput, that is, DFT-spread-OFDM with spectrum division control (SDC) and adaptive selection of SC-FDMA and OFDM (SC+OFDM). The number of discontinuous spectrums is denoted as spectrum division (SD). For DFT-S-OFDM, we define a parameter max SD as the upper limit of SD. We evaluate our proposed schemes in bandwidth under 20MHz and find that SC+OFDM as well as SDC with common max SD or UE-specific max SD can improve average throughput while their cell-edge user throughput can approach that of SC-FDMA. In the case of bandwidth over 20MHz, we consider key factors to decide a feasible access scheme for aggregating several 20MHz-wide bands.

  17. Increasing access to kidney transplantation for sensitized recipient through three-way kidney paired donation with desensitization: The first Indian report

    PubMed Central

    Kute, Vivek B; Patel, Himanshu V; Shah, Pankaj R; Modi, Pranjal R; Shah, Veena R; Rizvi, Sayyed J; Pal, Bipin C; Modi, Manisha P; Shah, Priya S; Varyani, Umesh T; Wakhare, Pavan S; Shinde, Saiprasad G; Ghodela, Viajay A; Patel, Minaxi H; Trivedi, Varsha B; Trivedi, Hargovind L

    2016-01-01

    The combination of kidney paired donation (KPD) with desensitization represents a promising method of increasing the rate of living donor kidney transplantation (LDKT) in immunologically challenging patients. Patients who are difficult to match and desensitize due to strong donor specific antibody are may be transplanted by a combination of desensitization and KPD protocol with more immunologically favorable donor. We present our experience of combination of desensitization protocol with three-way KPD which contributed to successful LDKT in highly sensitized end stage renal disease patient. All recipients were discharged with normal and stable allograft function at 24 mo follow up. We believe that this is first report from India where three-way KPD exchange was performed with the combination of KPD and desensitization. The combination of desensitization protocol with KPD improves access and outcomes of LDKT. PMID:27803919

  18. [Recruitment of smokers in the Rio de Janeiro subway, Brazil, as a strategy to increase access to quitline services: the impact of novelty].

    PubMed

    Szklo, André Salem; Coutinho, Evandro da Silva Freire; Barros, Helena Maria Tannhauser; Perez, Cristina; Moreira, Taís de Campos; Figueiró, Luciana Rizzieri; Pinho, Mariana; Carvalho, Valeska Figueiredo

    2009-11-01

    Creative and innovative strategies to recruit smokers are essential for improving tobacco control activities. Currently in Brazil, through health warning messages on cigarette packs, there is a permanent and intense spread of messages that provoke feelings of loss associated with smoking, which is important to encourage access to smoking quitlines. The study analyzed the call rate for telephone counseling after introducing a new strategy for reactive recruitment focused on the theme 'smoking causes shortness of breath', adapted to the subway setting in Rio de Janeiro, as compared to the rates for two existing reactive strategies. Regardless of age bracket, there was a higher response to the new proposed strategy. Despite the major awareness-raising in Brazil concerning the ills of tobacco, new communications formats approaching personally relevant themes can increase the number and range of smokers recruited for telephone counseling to support cessation.

  19. Increasing access to kidney transplantation for sensitized recipient through three-way kidney paired donation with desensitization: The first Indian report.

    PubMed

    Kute, Vivek B; Patel, Himanshu V; Shah, Pankaj R; Modi, Pranjal R; Shah, Veena R; Rizvi, Sayyed J; Pal, Bipin C; Modi, Manisha P; Shah, Priya S; Varyani, Umesh T; Wakhare, Pavan S; Shinde, Saiprasad G; Ghodela, Viajay A; Patel, Minaxi H; Trivedi, Varsha B; Trivedi, Hargovind L

    2016-10-16

    The combination of kidney paired donation (KPD) with desensitization represents a promising method of increasing the rate of living donor kidney transplantation (LDKT) in immunologically challenging patients. Patients who are difficult to match and desensitize due to strong donor specific antibody are may be transplanted by a combination of desensitization and KPD protocol with more immunologically favorable donor. We present our experience of combination of desensitization protocol with three-way KPD which contributed to successful LDKT in highly sensitized end stage renal disease patient. All recipients were discharged with normal and stable allograft function at 24 mo follow up. We believe that this is first report from India where three-way KPD exchange was performed with the combination of KPD and desensitization. The combination of desensitization protocol with KPD improves access and outcomes of LDKT.

  20. Increasing accessibility to the blind of virtual environments, using a virtual mobility aid based on the "EyeCane": feasibility study.

    PubMed

    Maidenbaum, Shachar; Levy-Tzedek, Shelly; Chebat, Daniel-Robert; Amedi, Amir

    2013-01-01

    Virtual worlds and environments are becoming an increasingly central part of our lives, yet they are still far from accessible to the blind. This is especially unfortunate as such environments hold great potential for them for uses such as social interaction, online education and especially for use with familiarizing the visually impaired user with a real environment virtually from the comfort and safety of his own home before visiting it in the real world. We have implemented a simple algorithm to improve this situation using single-point depth information, enabling the blind to use a virtual cane, modeled on the "EyeCane" electronic travel aid, within any virtual environment with minimal pre-processing. Use of the Virtual-EyeCane, enables this experience to potentially be later used in real world environments with identical stimuli to those from the virtual environment. We show the fast-learned practical use of this algorithm for navigation in simple environments.

  1. Bandwidth auction for SVC streaming in dynamic multi-overlay

    NASA Astrophysics Data System (ADS)

    Xiong, Yanting; Zou, Junni; Xiong, Hongkai

    2010-07-01

    In this paper, we study the optimal bandwidth allocation for scalable video coding (SVC) streaming in multiple overlays. We model the whole bandwidth request and distribution process as a set of decentralized auction games between the competing peers. For the upstream peer, a bandwidth allocation mechanism is introduced to maximize the aggregate revenue. For the downstream peer, a dynamic bidding strategy is proposed. It achieves maximum utility and efficient resource usage by collaborating with a content-aware layer dropping/adding strategy. Also, the convergence of the proposed auction games is theoretically proved. Experimental results show that the auction strategies can adapt to dynamic join of competing peers and video layers.

  2. Network Monitoring and Diagnosis Based on Available Bandwidth Measurement

    DTIC Science & Technology

    2006-05-01

    applications are VoIP and IPTV . VoIP is often designed in a way that voice traffic share the same link with other IP traffic (e.g., web traffic). It is...scheduling in VoIP devices. For IPTV , each channel generally oc- cupies several Mbps of bandwidth, to support multi-channel IPTV , available bandwidth is...important. However, I believe this situation will soon be different, with the deployment of high-bandwidth applications like IPTV . I am looking forward to

  3. Broadening the potential bandwidth of piezoelectric transducers by partial depolarization

    SciTech Connect

    Hariti, Sid Ahmed; Hole, Stephane; Lewiner, Jacques

    2001-06-18

    Elastic waves are used more and more in a nondestructive way to probe the physical properties of materials. The resolution of the images or the accuracy of the measurements is directly associated with the ultrasonic signal bandwidth and amplitude a system can generate or detect. The authors propose a technique to broaden the potential bandwidth of piezoelectric generators and sensors, which is based on utilizing a nonuniformly-polarized piezoelectric material. Both simulated and experimental responses are shown. They are in good agreement and exhibit a useful bandwidth over several natural harmonics of the piezoelectric transducer. {copyright} 2001 American Institute of Physics.

  4. Durations required to distinguish noise and tone: Effects of noise bandwidth and frequency.

    PubMed

    Taghipour, Armin; Moore, Brian C J; Edler, Bernd

    2016-05-01

    Perceptual audio coders exploit the masking properties of the human auditory system to reduce the bit rate in audio recording and transmission systems; it is intended that the quantization noise is just masked by the audio signal. The effectiveness of the audio signal as a masker depends on whether it is tone-like or noise-like. The determination of this, both physically and perceptually, depends on the duration of the stimuli. To gather information that might improve the efficiency of perceptual coders, the duration required to distinguish between a narrowband noise and a tone was measured as a function of center frequency and noise bandwidth. In experiment 1, duration thresholds were measured for isolated noise and tone bursts. In experiment 2, duration thresholds were measured for tone and noise segments embedded within longer tone pulses. In both experiments, center frequencies were 345, 754, 1456, and 2658 Hz and bandwidths were 0.25, 0.5, and 1 times the equivalent rectangular bandwidth of the auditory filter at each center frequency. The duration thresholds decreased with increasing bandwidth and with increasing center frequency up to 1456 Hz. It is argued that the duration thresholds depended mainly on the detection of amplitude fluctuations in the noise bursts.

  5. Bandwidth tunable guided-mode resonance filter using contact coupled gratings at oblique incidence

    NASA Astrophysics Data System (ADS)

    Sang, Tian; Wang, Yueke; Li, Junlang; Zhou, Jianyu; Jiang, Wenwen; Wang, Jicheng; Chen, Guoqing

    2017-01-01

    A novel bandwidth tunable guided-mode resonance filter (GMRF) is proposed based on the contact coupled gratings (CCGs) with the absentee layers at oblique incidence. The design principle of the CCGs with double absentee layers is presented. The lateral shift of the CCGs changes the magnetic field distributions of the waveguide mode in the grating cavity and the surface-confined mode at the cover/grating interface thus facilitates the dynamic control of both the spectral and angular bandwidth of the GMRF. The resonance locations are almost immune to the variation of the lateral shift of the CCGs. The sideband level of the GMRF is almost unaffected by the lateral shift due to the Brewster AR effect. The resonance peak red-shifts quasi-linearly as the incident angle is increased, and the resonance wavelength can be selected by merely tuning the incident angle. The tunable ranges of both the spectral and angular bandwidth can be significantly enhanced by increasing the refractive-index contrast. Low-sideband reflection with controllable bandwidth at 650 nm is designed to demonstrate this concept.

  6. Effects of increase in temperature and open water on transmigration and access to health care by the Nenets reindeer herders in northern Russia

    PubMed Central

    Amstislavski, Philippe; Zubov, Leonid; Chen, Herman; Ceccato, Pietro; Pekel, Jean-Francois; Weedon, Jeremy

    2013-01-01

    Background The indigenous Nenets reindeer herders in northern Russia annually migrate several hundred kilometers between summer and winter pastures. In the warming climate, ice-rich permafrost and glaciers are being significantly reduced and will eventually disappear from parts of the Arctic. The emergent changes in hydrological cycles have already led to substantial increases in open water that stays unfrozen for longer periods of time. This environmental change has been reported to compromise the nomadic Nenets’ traditional way of life because the presence of new water in the tundra reduces the Nenets’ ability to travel by foot, sled, or motor vehicle from the summer transitory tundra campsites in order to access healthcare centers in villages. New water can also impede their access to family and community at other herder camps and in the villages. Although regional and global models predicting hydrologic changes due to climate changes exist, the spatial resolution of these models is too coarse for studying how increases in open water affect health and livelihoods. To anticipate the full health impact of hydrologic changes, the current gap between globally forecasted scenarios and locally forecasted hydrologic scenarios needs to be bridged. Objectives We studied the effects of the autumn temperature anomalies and increases in open water on health care access and transmigration of reindeer herders on the Kanin Peninsula. Design Correlational and time series analyses were completed. Methods The study population consisted of 370 full-time, nomadic reindeer herders. We utilized clinical visit records, studied surface temperature anomalies during autumn migrations, and used remotely sensed imagery to detect water bodies. Spearman correlation was used to measure the relationship between temperature anomalies and the annual arrival of the herders at the Nes clinic for preventive and primary care. Piecewise regression was used to model change in mean autumnal

  7. Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

    DOE PAGES

    Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun; ...

    2014-07-14

    Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na2SO4 and NH4H2PO4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25 g DNA/g clay with themore » Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.« less

  8. Improved Yield of High Molecular Weight DNA Coincides with Increased Microbial Diversity Access from Iron Oxide Cemented Sub-Surface Clay Environments

    SciTech Connect

    Hurt, Jr., Richard A.; Robeson II, Michael S.; Shakya, Migun; Moberly, James G.; Vishnivetskaya, Tatiana; Gu, Baohua; Elias, Dwayne A.

    2014-07-14

    Despite more than three decades of progress, efficient nucleic acid extraction from microbial communities has remained difficult, particularly from clay environments. Lysis with concentrated guanidine followed by concentrated sodium phosphate extraction supported DNA and RNA recovery from high iron, low humus content clay. Alterating the extraction pH or using other ionic solutions (Na2SO4 and NH4H2PO4) yielded no detectable nucleic acid. DNA recovered using a lysis solution with 500 mM phosphate buffer (PB) followed by a 1 M PB wash was 15.22±2.33 g DNA/g clay, with most DNA consisting of >20 Kb fragments, compared to 2.46±0.25 g DNA/g clay with the Powerlyzer soil DNA system (MoBio). Increasing [PB] in the lysis reagent coincided with increasing DNA fragment length. Rarefaction plots based on16S rRNA (V1/V3 region) pyrosequencing libraries from A-horizon and clay soils showed an ~80% and ~400% larger accessed diversity compared to a previous grinding protocol or the Powerlyzer soil DNA system, respectively. The observed diversity from the Firmicutes showed the strongest increase with >3-fold more bacterial species recovered using this system. Additionally, some OTU's having more than 100 sequences in these libraries were absent in samples extracted using the PowerLyzer reagents or the previous lysis method.

  9. Feasibility and Acceptability of Brighter Bites: A Food Co-Op in Schools to Increase Access, Continuity and Education of Fruits and Vegetables Among Low-Income Populations.

    PubMed

    Sharma, Shreela; Helfman, Lisa; Albus, Katherine; Pomeroy, Mike; Chuang, Ru-Jye; Markham, Christine

    2015-08-01

    Intake of fruits and vegetables (F&V) continues to be low in children in the United States. The purpose of this study was to conduct a pilot feasibility evaluation of Brighter Bites, a school-based food co-op to provide access to fresh F&V and nutrition education to low-income children and their families. Brighter Bites is a 16-week school-based food co-op consisting of: (1) Weekly distribution of 50-60 servings of fresh F&V; (2) Weekly bilingual parent handouts and recipe demonstrations; and (3) implementing CATCH, a coordinated school health program in schools. Brighter Bites was pilot tested using a pre-post evaluation design in one charter school in Houston, TX, USA (n = 57 3rd grade parent-child dyads; 94.1 % Hispanic, 91 % low-income). Evaluation, at baseline, midpoint, and post-intervention, included self-reported child and parent surveys on psychosocial factors, dietary habits and mealtime practices. Pearson's Chi square test, Fisher's exact-test or paired t test were used to determine changes pre- to post-intervention (at p < 0.05). Process data using parent surveys, teacher surveys, attendance logs, and produce cost data were used to determine feasibility and acceptability of program. Participants received on average 61 servings of F&V weekly for 16 weeks at the cost of $4.31/family/week. Results showed significant increases in child reported self-efficacy, outcome expectations and attitudes towards consuming F&V (p < 0.05). We found significant increases in child exposure to F&V and child preference of various F&V from baseline to post-intervention (p < 0.05). Parent surveys showed significant improvements in mealtime practices at home: decrease in children eating while watching TV, increase in eating dinner with the family, less fast food, less sugary drinks with meals, more children asking for F&V as snacks. Process data showed 98 % retention rate and high parent acceptability of program components. Brighter Bites is a promising strategy to increase F

  10. Highly efficient frequency conversion with bandwidth compression of quantum light

    PubMed Central

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks. PMID:28134242

  11. 47 CFR 74.1236 - Emission and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations and FM Broadcast Booster Stations § 74.1236 Emission and bandwidth. (a) The license of a...

  12. 47 CFR 74.1236 - Emission and bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) BROADCAST RADIO SERVICES EXPERIMENTAL RADIO, AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES FM Broadcast Translator Stations and FM Broadcast Booster Stations § 74.1236 Emission and bandwidth. (a) The license of a...

  13. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... reference bandwidth. (2) When using transmissions employing digital modulation techniques: (i) For operating... modulates a single carrier, digital modulation techniques are considered as being employed when digital... digital modulation signal and the deviation produced by any frequency division multiplex (FDM)...

  14. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... reference bandwidth. (2) When using transmissions employing digital modulation techniques: (i) For operating... modulates a single carrier, digital modulation techniques are considered as being employed when digital... digital modulation signal and the deviation produced by any frequency division multiplex (FDM)...

  15. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... reference bandwidth. (2) When using transmissions employing digital modulation techniques: (i) For operating... modulates a single carrier, digital modulation techniques are considered as being employed when digital... digital modulation signal and the deviation produced by any frequency division multiplex (FDM)...

  16. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... reference bandwidth. (2) When using transmissions employing digital modulation techniques: (i) For operating... modulates a single carrier, digital modulation techniques are considered as being employed when digital... digital modulation signal and the deviation produced by any frequency division multiplex (FDM)...

  17. Highly efficient frequency conversion with bandwidth compression of quantum light

    NASA Astrophysics Data System (ADS)

    Allgaier, Markus; Ansari, Vahid; Sansoni, Linda; Eigner, Christof; Quiring, Viktor; Ricken, Raimund; Harder, Georg; Brecht, Benjamin; Silberhorn, Christine

    2017-01-01

    Hybrid quantum networks rely on efficient interfacing of dissimilar quantum nodes, as elements based on parametric downconversion sources, quantum dots, colour centres or atoms are fundamentally different in their frequencies and bandwidths. Although pulse manipulation has been demonstrated in very different systems, to date no interface exists that provides both an efficient bandwidth compression and a substantial frequency translation at the same time. Here we demonstrate an engineered sum-frequency-conversion process in lithium niobate that achieves both goals. We convert pure photons at telecom wavelengths to the visible range while compressing the bandwidth by a factor of 7.47 under preservation of non-classical photon-number statistics. We achieve internal conversion efficiencies of 61.5%, significantly outperforming spectral filtering for bandwidth compression. Our system thus makes the connection between previously incompatible quantum systems as a step towards usable quantum networks.

  18. Tunable Bandwidth Quantum Well Infrared Photo Detector (TB-QWIP)

    DTIC Science & Technology

    2003-12-01

    conduction band called the band gap of the material. In a semiconductor the band gap is the minimum energy necessary for an electron to transfer from the...the optical energy from a heated object, instead of relying directly on the transfer of heat energy (like thermal detectors do). A quantum well can...to achieve electronically tunable bandwidth quantum well infrared photo detectors (Choi K. K. 1), or tunable bandwidth quantum dot infrared photo

  19. Electro-Optic Characterisation of Extremely Wide Bandwidth Electrical Signals

    DTIC Science & Technology

    1993-02-01

    In this report an ultrafast electro - optic sampling system suitable for applications such as device characterisation is described. The aperture time of the sampler is calculated to be about 290 fs, implying an attainable device bandwidth in excess of 300 GHz. The sampler was characterised using a test pulse with approximately 12 GHz of frequency content, and the results compared to those obtained from an 18 GHz digital sampling oscilloscope. Signal Processing, Bandwidth, Frequencies, Oscilloscopes.

  20. Using a Learning Collaborative Strategy With Office-based Practices to Increase Access and Improve Quality of Care for Patients With Opioid Use Disorders

    PubMed Central

    Nordstrom, Benjamin R.; Saunders, Elizabeth C.; McLeman, Bethany; Meier, Andrea; Xie, Haiyi; Lambert-Harris, Chantal; Tanzman, Beth; Brooklyn, John; King, Gregory; Kloster, Nels; Lord, Clifton Frederick; Roberts, William; McGovern, Mark P.

    2016-01-01

    Objectives Rapidly escalating rates of heroin and prescription opioid use have been widely observed in rural areas across the United States. Although US Food and Drug Administration-approved medications for opioid use disorders exist, they are not routinely accessible to patients. One medication, buprenorphine, can be prescribed by waivered physicians in office-based practice settings, but practice patterns vary widely. This study explored the use of a learning collaborative method to improve the provision of buprenorphine in the state of Vermont. Methods We initiated a learning collaborative with 4 cohorts of physician practices (28 total practices). The learning collaborative consisted of a series of 4 face-to-face and 5 teleconference sessions over 9 months. Practices collected and reported on 8 quality-improvement data measures, which included the number of patients prescribed buprenorphine, and the percent of unstable patients seen weekly. Changes from baseline to 8 months were examined using a p-chart and logistic regression methodology. Results Physician engagement in the learning collaborative was favorable across all 4 cohorts (85.7%). On 6 of the 7 quality-improvement measures, there were improvements from baseline to 8 months. On 4 measures, these improvements were statistically significant (P < 0.001). Importantly, practice variation decreased over time on all measures. The number of patients receiving medication increased only slightly (3.4%). Conclusions Results support the effectiveness of a learning collaborative approach to engage physicians, modestly improve patient access, and significantly reduce practice variation. The strategy is potentially generalizable to other systems and regions struggling with this important public health problem. PMID:26900669

  1. Increasing Community Access to Fresh Fruits and Vegetables: A Case Study of the Farm Fresh Market Pilot Program in Cobb County, Georgia, 2014

    PubMed Central

    Coleman, Anne-Marie; Hermstad, April K.; Honeycutt, Sally; Munoz, Jennifer; Loh, Lorna; Brown, Agnes F.; Shipley, Rebecca; Kegler, Michelle C.

    2016-01-01

    Background Ecological models of health suggest that to effectively prevent chronic disease, community food environments must support healthy eating behaviors. However, disparities in access to healthy foods persist in the United States. Community Context The Farm Fresh Market (FFM) was a fruit and vegetable market that sold low-cost fresh produce in Cobb County, Georgia in 2014. Methods This case study describes the development of the FFM through a community engagement process and presents evaluation results from the project’s pilot implementation. Community engagement strategies included forming a community advisory board, conducting a needs assessment, and contracting with a community-based organization to implement the FFM. Outcome In the pilot year, the FFM served an average of 28.7 customers and generated an average of $140.20 in produce sales per market day. Most returning customers lived in the local community and reported a range of socioeconomic backgrounds. Most returning customers strongly agreed that the FFM made it easier (69.0%) and less expensive (79.0%) for them to buy fresh fruits and vegetables, reported that they ate more vegetables (65.0%) and fruit (55.0%) as a result of the FFM, and reported that they were very satisfied with the FFM overall (92.0%). Interpretation Results from this community case study underscore the importance of engaging communities in the development of community food environment interventions. Results also suggest that the FFM initiative was a feasible and acceptable way to respond to the community-identified public health priority of increasing access to healthy foods. PMID:26963860

  2. Electro-optic bandwidth manipulation of quantum light (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Karpinski, Michal; Jachura, Michal; Wright, Laura J.; Smith, Brian J.

    2016-04-01

    means of a highly dispersive chirped fiber Bragg grating. We verify the non-classicality of spectrally shifted single photons by measuring high-visibility Hong-Ou-Mandel interference using a reference single photon pulse. Spectral compression is based on the time lens principle, which requires locking optical pulses to approximately quadratic region of sinusoidal phase modulation. We utilize both 10 GHz and 40 GHz RF driving frequencies. Bandwidth compression is achieved by chirping the single photon pulse using an appropriate length of single-mode fibre and subsequently subjecting it to the action of the time lens. We verify spectral compression directly using the aforementioned spectrally-resolved heralded single photon counting method. We achieve 3-fold spectral compression of 2 nm bandwidth single photon pulses using 40 GHZ modulation frequency, and 6-fold spectral compression of 0.9 nm bandwidth single photon pulses using 10 GHz modulation frequency. Overall transmission of our set-up exceeding 30% enables practical usability of our spectral compression method which we demonstrate experimentally by showing an increased photon flux through a narrowband filter. Our results present an important contribution towards implementing quantum information processing in the spectral-temporal degree of freedom of a photon. In the context of quantum networks they present an enabling tool towards efficient photonic interfacing of different quantum information processing platforms.

  3. Performance of a High-Concentration Erbium-Doped Fiber Amplifier with 100 nm Amplification Bandwidth

    SciTech Connect

    Hajireza, P.; Shahabuddin, N. S.; Abbasi-Zargaleh, S.; Emami, S. D.; Abdul-Rashid, H. A.; Yusoff, Z.

    2010-07-07

    Increasing demand for higher bandwidth has driven the need for higher Wavelength Division Multiplexing (WDM) channels. One of the requirements to achieve this is a broadband amplifier. This paper reports the performance of a broadband, compact, high-concentration and silica-based erbium-doped fiber amplifier. The amplifier optimized to a 2.15 m long erbium-doped fiber with erbium ion concentration of 2000 ppm. The gain spectrum of the amplifier has a measured amplification bandwidth of 100 nm using a 980 nm laser diode with power of 150 mW. This silica-based EDFA shows lower noise figure, higher gain and wider bandwidth in shorter wavelengths compared to Bismuth-based EDFA with higher erbium ion concentration of 3250 ppm at equivalent EDF length. The silica-based EDF shows peak gain at 22 dB and amplification bandwidth between 1520 nm and 1620 nm. The lowest noise figure is 5 dB. The gain is further improved with the implementation of enhanced EDFA configurations.

  4. Shared path protection through reconstructing sharable bandwidth based on spectrum segmentation for elastic optical networks

    NASA Astrophysics Data System (ADS)

    Liu, Huanlin; Zhang, Mingjia; Yi, Pengfei; Chen, Yong

    2016-12-01

    In order to address the problems of spectrum fragmentation and low sharing degree of spectrum resources in survivable elastic optical networks, an improved algorithm, called shared path protection by reconstructing sharable bandwidth based on spectrum segmentation (SPP-RSB-SS), is proposed in the paper. In the SPP-RSB-SS algorithm, for reducing the number of spectrum fragmentations and improving the success rate of spectrum allocation, the whole spectrum resource is partitioned into several spectrum segments. And each spectrum segment is allocated to the requests with the same bandwidth requirement in priority. Meanwhile, the protection path with higher spectrum sharing degree is selected through optimizing the link cost function and reconstructing sharable bandwidth. Hence, the protection path can maximize the sharable spectrum usage among multiple protection paths. The simulation results indicate that the SPP-RSB-SS algorithm can increase the sharing degree of protection spectrum effectively. Furthermore, the SPP-RSB-SS algorithm can enhance the spectrum utilization, and reduce the bandwidth blocking probability significantly.

  5. Sensitivity and 3 dB Bandwidth in Single and Series-Connected Tunneling Magnetoresistive Sensors

    PubMed Central

    Dąbek, Michał; Wiśniowski, Piotr; Stobiecki, Tomasz; Wrona, Jerzy; Cardoso, Susana; Freitas, Paulo P.

    2016-01-01

    As single tunneling magnetoresistive (TMR) sensor performance in modern high-speed applications is limited by breakdown voltage and saturation of the sensitivity, for higher voltage applications (i.e., compatible to 1.8 V, 3.3 V or 5 V standards) practically only a series connection can be applied. Thus, in this study we focused on sensitivity, 3 dB bandwidth and sensitivity-bandwidth product (SBP) dependence on the DC bias voltage in single and series-connected TMR sensors. We show that, below breakdown voltage, the strong bias influence on sensitivity and the 3 dB frequency of a single sensor results in higher SBP than in a series connection. However, the sensitivity saturation limits the single sensor SBP which, under 1 V, reaches the same level of 2000 MHz∙V/T as in a series connection. Above the single sensor breakdown voltage, linear sensitivity dependence on the bias and the constant 3 dB bandwidth of the series connection enable increasing its SBP up to nearly 10,000 MHz∙V/T under 5 V. Thus, although by tuning bias voltage it is possible to control the sensitivity-bandwidth product, the choice between the single TMR sensor and the series connection is crucial for the optimal performance in the high frequency range. PMID:27809223

  6. Sensitivity and 3 dB Bandwidth in Single and Series-Connected Tunneling Magnetoresistive Sensors.

    PubMed

    Dąbek, Michał; Wiśniowski, Piotr; Stobiecki, Tomasz; Wrona, Jerzy; Cardoso, Susana; Freitas, Paulo P

    2016-10-31

    As single tunneling magnetoresistive (TMR) sensor performance in modern high-speed applications is limited by breakdown voltage and saturation of the sensitivity, for higher voltage applications (i.e., compatible to 1.8 V, 3.3 V or 5 V standards) practically only a series connection can be applied. Thus, in this study we focused on sensitivity, 3 dB bandwidth and sensitivity-bandwidth product (SBP) dependence on the DC bias voltage in single and series-connected TMR sensors. We show that, below breakdown voltage, the strong bias influence on sensitivity and the 3 dB frequency of a single sensor results in higher SBP than in a series connection. However, the sensitivity saturation limits the single sensor SBP which, under 1 V, reaches the same level of 2000 MHz∙V/T as in a series connection. Above the single sensor breakdown voltage, linear sensitivity dependence on the bias and the constant 3 dB bandwidth of the series connection enable increasing its SBP up to nearly 10,000 MHz∙V/T under 5 V. Thus, although by tuning bias voltage it is possible to control the sensitivity-bandwidth product, the choice between the single TMR sensor and the series connection is crucial for the optimal performance in the high frequency range.

  7. Scaling Mesa Indium Phosphide DHBTs to Record Bandwidths

    NASA Astrophysics Data System (ADS)

    Lobisser, Evan

    Indium phosphide heterojunction bipolar transistors are able to achieve higher bandwidths at a given feature size than transistors in the Silicon material system for a given feature size. Indium phosphide bipolar transistors demonstrate higher breakdown voltages at a given bandwidth than both Si bipolars and field effect transistors in the InP material system. The high bandwidth of InP HBTs results from both intrinsic material parameters and bandgap engineering through epitaxial growth. The electron mobility in the InGaAs base and saturation velocity in the InP collector are both approximately three times higher than their counterparts in the SiGe material system. Resistance of the base can be made very low due to the large offset in the valence band between the InP emitter and the InGaAs base, which allows the base to be doped on the order of 1020 cm-3 with negligible reduction in emitter injection efficiency. This thesis deals with type-I, NPN dual-heterojunction bipolar transistors. The emitters are InP, and the base is InGaAs. There is a thin (˜ 10 nm) n-type InGaAs "setback" region, followed by a chirped superlattice InGaAs/InAlAs grade to the InP collector. The setback, grade, and collector are all lightly doped n-type. The emitter and collector are contacted through thin (˜ 5 nm) heavily doped n-type InGaAs layers to reduce contact resistivity. The primary focus of this work is increasing the bandwidth of InP HBTs through the proportional scaling of the device dimensions, both layer thicknesses and junction areas, as well as the reduction of the contact resistivities associated with the transistor. Essentially, all RC time constants and transit times must be reduced by a factor of two to double a transistor's bandwidth. Chapter 2 describes in detail the scaling laws and design principles for high frequency bipolar transistor design. A low-stress, blanket sputter deposited composite emitter metal process was developed. Refractory metal base contacts were

  8. Bandwidths for the perception of head orientation decrease during childhood.

    PubMed

    Vida, Mark D; Wilson, Hugh R; Maurer, Daphne

    2014-05-01

    Adults use the orientation of people's heads as a cue to the focus of their attention. We examined developmental changes in mechanisms underlying sensitivity to head orientation during childhood. Eight-, 10-, 12-year-olds, and adults were adapted to a frontal face view or a 20° left or right side view before judging the orientation of a face at or near frontal. After frontal adaptation, there were no age differences in judgments of head orientation. However, after adaptation to a 20° left or right side view, aftereffects were larger and sensitivity to head orientation was lower in 8- and 10-year-olds than in adults, with no difference between 12-year-olds and adults. A computational model indicates that these results can be modeled as a consequence of decreasing neural tuning bandwidths and decreasing additive internal noise during childhood, and/or as a consequence of increasing inhibition during childhood. These results provide the first evidence that neural mechanisms underlying sensitivity to head orientation undergo considerable refinement during childhood.

  9. The effect of stimulus bandwidth on the nonlinear-derived tone-burst-evoked otoacoustic emission.

    PubMed

    Lewis, James D; Goodman, Shawn S

    2014-12-01

    Intermodulation distortion has been hypothesized as a mechanism contributing to the generation of short-latency (SL) components in the transient-evoked otoacoustic emission (TEOAE). Presumably, nonlinear interactions between the frequency components within the evoking stimulus induce cochlear distortion products, which mix in the cochlea and ear canal with reflected energy from each stimulus-frequency's tonotopic place. The mixing of these different components is evidenced in the bandpass-filtered emission waveform as a series of different latency peaks. The current study tested the hypothesis that intermodulation distortion, induced within the spectral bandwidth of the evoking stimulus, is the primary mechanism through which the SL components are generated. The nonlinear-derived tone-burst-evoked OAE (TBOAEnl) was evoked using 2-kHz tone bursts with durations of 3, 6, 12, and 24 cycles. As tone burst duration doubled, the spectral bandwidth was halved. It was hypothesized that contributions to the TBOAEnl from SL components would decrease as tone burst duration increased and spectral bandwidth decreased, if the SL components were generated through intermodulation distortion. Despite differences in spectral bandwidth between the evoking stimuli, the latencies and magnitudes of the different latency components between the 3- and 6-cycle TBOAEnl were comparable. The 12- and 24-cycle TBOAEnl envelopes were characteristic of destructive phase interactions between different latency components overlapping in time. The different latency components in the 3- and 6-cycle TBOAEnl introduced a characteristic level dependency to TBOAEnl magnitude and latency when analyzed across a broad time window spanning the different components. A similar dependency described the 12- and 24-cycle TBOAEnl input/output and latency-intensity functions, suggesting that the SL components evident in the shorter-duration TBOAEnl equally contributed to the longer-duration TBOAEnl, despite

  10. Fourier-transform electron spin resonance with bandwidth-compensated chirp pulses

    NASA Astrophysics Data System (ADS)

    Doll, Andrin; Jeschke, Gunnar

    2014-09-01

    Electron spin echo experiments using chirp pulses at X-band around 9 GHz have been performed with a home-built spectrometer based on an arbitrary waveform generator. Primary echoes without phase dispersion were obtained by employing the Böhlen-Bodenhausen scheme with the refocusing pulse being half as long as the coherence-generating pulse. To account for physical bandwidth limitation by the resonator, the instantaneous sweep rate of the chirps was adapted to the spectrometer’s frequency response function, which can be recorded from the sample under study within a few minutes. Such bandwidth-compensated chirp pulses are experimentally shown to achieve an almost uniform excitation bandwidth that exceeds the resonator bandwidth. This uniform excitation allows for computing frequency-domain spectra by Fourier-transformation (FT) of the echo signal. For a nitroxide in dilute solid solution with a spectral width of 200 MHz, the FT EPR spectrum agrees remarkably well with a field-swept echo-detected EPR spectrum. The overall spectral perturbation for operation far beyond the resonator bandwidth was characterized by acquiring a 700 MHz wide spectral range of a copper (II) EPR spectrum with nearly uniform amplitude with excitation and refocusing pulses of 200 and 100 ns, respectively. Furthermore, peculiarities were observed in solid-state FT EPR spectra of disordered systems. To understand these peculiarities two-dimensional data sets were acquired that correlate the FT EPR spectrum to inversion recovery or nuclear modulation. The echo envelope modulation experiments reveal echo decay rates increased by enhanced instantaneous diffusion and passage-specific effects in the nuclear modulations. The latter effect can be suppressed by nuclear modulation averaging. Apparent longitudinal relaxation times for a given subset of orientations are influenced by nuclear modulation effects. Proper extraction of orientation-dependent relaxation times thus requires an experimental

  11. Bandwidth control of wavelength-selective uncooled infrared sensors using two-dimensional plasmonic absorbers

    NASA Astrophysics Data System (ADS)

    Ogawa, Shinpei; Fujisawa, Daisuke; Kimata, Masafumi

    2016-05-01

    Although standard uncooled infrared (IR) sensors can be used to record information such as the shape, position, and average radiant intensity of objects, these devices cannot capture color (that is, wavelength) data. Achieving wavelength selectivity would pave the way for the development of advanced uncooled IR sensors capable of providing color information as well as multi-color image sensors that would have significant advantages in applications such as fire detection, gas analysis, hazardous material recognition, and biological analysis. We have previously demonstrated an uncooled IR sensor incorporating a two-dimensional plasmonic absorber (2D PLA) that exhibits wavelength selectivity over a wide range in the mid- and long-IR regions. This PLA has a 2D Au-based periodic array of dimples, in which surface plasmon modes are induced and wavelength-selective absorption occurs. However, the dependence of the absorption bandwidth on certain structural parameters has yet to be clarified. The bandwidth of such devices is a vital factor when considering the practical application of these sensors to tasks such as gas detection. In the present study, control of the bandwidth was theoretically investigated using a rigorous coupled wave analysis approach. It is demonstrated that the dimple sidewall structure has a significant impact on the bandwidth and can be used to control both narrow- and broadband absorption. Increasing the sidewall slope was found to decrease the bandwidth due to suppression of cavity-mode resonance in the depth direction of the dimples. These results will contribute to the development of high-resolution, wavelength-selective uncooled IR sensors.

  12. Fourier-transform electron spin resonance with bandwidth-compensated chirp pulses.

    PubMed

    Doll, Andrin; Jeschke, Gunnar

    2014-09-01

    Electron spin echo experiments using chirp pulses at X-band around 9GHz have been performed with a home-built spectrometer based on an arbitrary waveform generator. Primary echoes without phase dispersion were obtained by employing the Böhlen-Bodenhausen scheme with the refocusing pulse being half as long as the coherence-generating pulse. To account for physical bandwidth limitation by the resonator, the instantaneous sweep rate of the chirps was adapted to the spectrometer's frequency response function, which can be recorded from the sample under study within a few minutes. Such bandwidth-compensated chirp pulses are experimentally shown to achieve an almost uniform excitation bandwidth that exceeds the resonator bandwidth. This uniform excitation allows for computing frequency-domain spectra by Fourier-transformation (FT) of the echo signal. For a nitroxide in dilute solid solution with a spectral width of 200MHz, the FT EPR spectrum agrees remarkably well with a field-swept echo-detected EPR spectrum. The overall spectral perturbation for operation far beyond the resonator bandwidth was characterized by acquiring a 700MHz wide spectral range of a copper (II) EPR spectrum with nearly uniform amplitude with excitation and refocusing pulses of 200 and 100ns, respectively. Furthermore, peculiarities were observed in solid-state FT EPR spectra of disordered systems. To understand these peculiarities two-dimensional data sets were acquired that correlate the FT EPR spectrum to inversion recovery or nuclear modulation. The echo envelope modulation experiments reveal echo decay rates increased by enhanced instantaneous diffusion and passage-specific effects in the nuclear modulations. The latter effect can be suppressed by nuclear modulation averaging. Apparent longitudinal relaxation times for a given subset of orientations are influenced by nuclear modulation effects. Proper extraction of orientation-dependent relaxation times thus requires an experimental setup

  13. Enhancing the bandwidth of piezoelectric composite transducers for air-coupled non-destructive evaluation.

    PubMed

    Banks, Robert; O'Leary, Richard L; Hayward, Gordon

    2017-03-01

    This paper details the development of a novel method for increasing the operational bandwidth of piezocomposites without the need for lossy backing material, the aim being to increase fractional bandwith by geometrical design. Removing the need for lossy backing materials, should in turn increase the transmit efficiency in the desired direction of propagation. Finite element analysis has been employed to determine the mode of operation of the new piezocomposite devices and shows good correlation with that derived experimentally. Through a series of practical and analytical methods it has been shown that additional thickness mode resonances can be introduced into the structure by a simple machining process. The shaped composites described in this paper offer increased operational bandwidth. A simple example of a two step thickness design is described to validate and illustrate the principle. A more complex conical design is presented that illustrates a possible tenfold increase in bandwidth from 30kHz to 300kHz, operating in air without backing. An illustration of the applicability of this type of transducer technology for frequency agile guided mode non-destructive evaluation is then presented.

  14. Ambient and Cryogenic, Decade Bandwidth, Low Noise Receiving System for Radio Astronomy Using Sinuous Antenna

    NASA Astrophysics Data System (ADS)

    Gawande, Rohit Sudhir

    Traditionally, radio astronomy receivers have been limited to bandwidths less than an octave, and as a result multiple feeds and receivers are necessary to observe over a wide bandwidth. Next generation of instruments for radio astronomy will benefit greatly from reflector antenna feeds that demonstrate very wide instantaneous bandwidth, and exhibit low noise behavior. There is an increasing interest in wideband systems from both the cost and science point of view. A wideband feed will allow simultaneous observations or sweeps over a decade or more bandwidth. Instantaneous wide bandwidth is necessary for detection of short duration pulses. Future telescopes like square kilometer array (SKA), consisting of 2000 to 3000 coherently connected antennas and covering a frequency range of 70 MHz to 30 GHz, will need decade bandwidth single pixel feeds (SPFs) along with integrated LNAs to achieve the scientific objectives in a cost effective way. This dissertation focuses on the design and measurement of a novel decade bandwidth sinuous-type, dual linear polarized, fixed phase center, low loss feed with an integrated LNA. A decade bandwidth, low noise amplifier is specially designed for noise match to the higher terminal impedance encountered by this antenna yielding an improved sensitivity over what is possible with conventional 50 O amplifiers. The self-complementary, frequency independent nature of the planar sinuous geometry results in a nearly constant beam pattern and fixed phase center over more than a 10:1 operating frequency range. In order to eliminate the back-lobe response over such a wide frequency range, we have projected the sinuous pattern onto a cone, and a ground plane is placed directly behind the cone's apex. This inverted, conical geometry assures wide bandwidth operation by locating each sinuous resonator a quarter wavelength above the ground plane. The presence of a ground plane near a self complementary antenna destroys the self complementary nature

  15. Effect of camera resolution and bandwidth on facial affect recognition.

    PubMed

    Cruz, Mario; Cruz, Robyn Flaum; Krupinski, Elizabeth A; Lopez, Ana Maria; McNeeley, Richard M; Weinstein, Ronald S

    2004-01-01

    This preliminary study explored the effect of camera resolution and bandwidth on facial affect recognition, an important process and clinical variable in mental health service delivery. Sixty medical students and mental health-care professionals were recruited and randomized to four different combinations of commonly used teleconferencing camera resolutions and bandwidths: (1) one chip charged coupling device (CCD) camera, commonly used for VHSgrade taping and in teleconferencing systems costing less than $4,000 with a resolution of 280 lines, and 128 kilobytes per second bandwidth (kbps); (2) VHS and 768 kbps; (3) three-chip CCD camera, commonly used for Betacam (Beta) grade taping and in teleconferencing systems costing more than $4,000 with a resolution of 480 lines, and 128 kbps; and (4) Betacam and 768 kbps. The subjects were asked to identify four facial affects dynamically presented on videotape by an actor and actress presented via a video monitor at 30 frames per second. Two-way analysis of variance (ANOVA) revealed a significant interaction effect for camera resolution and bandwidth (p = 0.02) and a significant main effect for camera resolution (p = 0.006), but no main effect for bandwidth was detected. Post hoc testing of interaction means, using the Tukey Honestly Significant Difference (HSD) test and the critical difference (CD) at the 0.05 alpha level = 1.71, revealed subjects in the VHS/768 kbps (M = 7.133) and VHS/128 kbps (M = 6.533) were significantly better at recognizing the displayed facial affects than those in the Betacam/768 kbps (M = 4.733) or Betacam/128 kbps (M = 6.333) conditions. Camera resolution and bandwidth combinations differ in their capacity to influence facial affect recognition. For service providers, this study's results support the use of VHS cameras with either 768 kbps or 128 kbps bandwidths for facial affect recognition compared to Betacam cameras. The authors argue that the results of this study are a consequence of the

  16. Impact of varying transmission bandwidth on image quality.

    PubMed

    Broderick, T J; Harnett, B M; Merriam, N R; Kapoor, V; Doarn, C R; Merrell, R C

    2001-01-01

    The objective of this paper is to determine the effect of varying transmission bandwidth on image quality in laparoscopic surgery. Surgeons located in remote operating rooms connected through a telemedicine link must be able to transmit medical images for interaction. Image clarity and color fidelity are of critical importance in telementoring laparoscopic procedures. The clarity of laparoscopic images was measured by assessing visual acuity using a video image of a Snellen eye chart obtained with standard diameter laparoscopes (2, 5, and 10 mm). The clarity of the local image was then compared to that of remote images transmitted using various bandwidths and connection protocols [33.6 Kbps POTS (IP), 128 Kbps ISDN, 384 Kbps ISDN, 10 Mbps LAN (IP)]. The laparoscopes were subsequently used to view standard color placards. These color images were sent via similar transmission bandwidths and connection protocols. The local and remote images of the color placards were compared to determine the effect of the transmission protocols on color fidelity. Use of laparoscopes of different diameter does not significantly affect image clarity or color fidelity as long as the laparoscopes are positioned at their optimal working distance. Decreasing transmission bandwidth does not significantly affect image clarity or color fidelity when sufficient time is allowed for the algorithms to redraw the remote image. Remote telementoring of laparoscopic procedures is feasible. However, low bandwidth connections require slow and/or temporarily stopped camera movements for the quality of the remote video image to approximate that of the local video image.

  17. Effective bandwidth guaranteed routing schemes for MPLS traffic engineering

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Jain, Nidhi

    2001-07-01

    In this work, we present online algorithms for dynamic routing bandwidth guaranteed label switched paths (LSPs) where LSP set-up requests (in terms of a pair of ingress and egress routers as well as its bandwidth requirement) arrive one by one and there is no a priori knowledge regarding future LSP set-up requests. In addition, we consider rerouting of LSPs in this work. Rerouting of LSPs has not been well studied in previous work on LSP routing. The need of LSP rerouting arises in a number of ways: occurrence of faults (link and/or node failures), re-optimization of existing LSPs' routes to accommodate traffic fluctuation, requests with higher priorities, and so on. We formulate the bandwidth guaranteed LSP routing with rerouting capability as a multi-commodity flow problem. The solution to this problem is used as the benchmark for comparing other computationally less costly algorithms studied in this paper. Furthermore, to more efficiently utilize the network resources, we propose online routing algorithms which route bandwidth demands over multiple paths at the ingress router to satisfy the customer requests while providing better service survivability. Traffic splitting and distribution over the multiple paths are carefully handled using table-based hashing schemes while the order of packets within a flow is preserved. Preliminary simulations are conducted to show the performance of different design choices and the effectiveness of the rerouting and multi-path routing algorithms in terms of LSP set-up request rejection probability and bandwidth blocking probability.

  18. Effect of internal optical loss on the modulation bandwidth of a quantum dot laser

    NASA Astrophysics Data System (ADS)

    Wu, Yuchang; Suris, Robert A.; Asryan, Levon V.

    2012-03-01

    We show that the internal optical loss, which increases with free-carrier density in the waveguide region, considerably reduces the modulation bandwidth ω-3 dB of a quantum dot laser. At a certain optimum value j0opt of the dc component of the injection current density, the maximum bandwidth ω-3dBmax is attained and the modulation response function becomes as flat as possible. With internal loss cross-section σint increasing and approaching its maximum tolerable value, ω-3dBmax decreases and becomes zero. As with j0opt, there also exists the optimum cavity length, at which ω-3 dB is highest; the larger is σint, the longer is the optimum cavity.

  19. Wide-bandwidth, wide-beamwidth, high-resolution, millimeter-wave imaging for concealed weapon detection

    NASA Astrophysics Data System (ADS)

    Sheen, David M.; Fernandes, Justin L.; Tedeschi, Jonathan R.; McMakin, Douglas L.; Jones, A. Mark; Lechelt, Wayne M.; Severtsen, Ronald H.

    2013-05-01

    Active millimeter-wave imaging is currently being used for personnel screening at airports and other high-security facilities. The cylindrical imaging techniques used in the deployed systems are based on licensed technology developed at the Pacific Northwest National Laboratory. The cylindrical and a related planar imaging technique form three-dimensional images by scanning a diverging beam swept frequency transceiver over a two-dimensional aperture and mathematically focusing or reconstructing the data into three-dimensional images of the person being screened. The resolution, clothing penetration, and image illumination quality obtained with these techniques can be significantly enhanced through the selection of the aperture size, antenna beamwidth, center frequency, and bandwidth. The lateral resolution can be improved by increasing the center frequency, or it can be increased with a larger antenna beamwidth. The wide beamwidth approach can significantly improve illumination quality relative to a higher frequency system. Additionally, a wide antenna beamwidth allows for operation at a lower center frequency resulting in less scattering and attenuation from the clothing. The depth resolution of the system can be improved by increasing the bandwidth. Utilization of extremely wide bandwidths of up to 30 GHz can result in depth resolution as fine as 5 mm. This wider bandwidth operation may allow for improved detection techniques based on high range resolution. In this paper, the results of an extensive imaging study that explored the advantages of using extremely wide beamwidth and bandwidth are presented, primarily for 10-40 GHz frequency band.

  20. Limited Bandwidth Recognition of Collective Behaviors in Bio-Inspired Swarms

    DTIC Science & Technology

    2014-05-09

    scalable human interaction with large bio-inspired robot swarms, namely, how do you know what the swarm is doing if you can’t observe every agent in the...uncertainty about the swarm’s actual behavior. Additionally, as robot swarms increase in size, bandwidth and time constraints limit the number of agents...limited samples of a small subset of agents. We present a novel framework for classifying the collective behavior of a bio-inspired robot swarm using

  1. Lasercomm system development for high-bandwidth terrestrial communications

    NASA Astrophysics Data System (ADS)

    Juarez, Juan C.; Souza, Katherine T.; Bos, Natalie G.; Brown, Andrea M.; Cannon, Brice M.; Petrillo, Keith G.; Riggins, James L.; Sluz, Joseph E.; Tomey, Hala J.; Venkat, Radha A.

    2016-05-01

    In recent years, various terrestrial free-space optical (FSO) communications systems have been demonstrated to achieve high-bandwidth communications between mobile platforms. The terminal architectures fall into three general categories: (1) single aperture systems with tip/tilt control, (2) multi-aperture system with tip/tilt control, and (3) single aperture systems with tip/tilt control and higher order adaptive optics correction. Terrestrial modem approaches generally use direct detection receivers because they provide high bandwidth capability (0.1-10 Gbps) without the complexity of coherent detection. Modems are often augmented with a mix of forward error correction (FEC), interleaving, and/or retransmission for improved data transport. This paper will present a terminal and modem architecture for a low-SWAP FSO communications system that enables robust, high-bandwidth communications under highly scintillated links as found in terrestrial applications such as air-to-air, air-to-surface, and surface-to-surface links.

  2. Maximum bandwidth snapshot channeled imaging polarimeter with polarization gratings

    NASA Astrophysics Data System (ADS)

    LaCasse, Charles F.; Redman, Brian J.; Kudenov, Michael W.; Craven, Julia M.

    2016-05-01

    Compact snapshot imaging polarimeters have been demonstrated in literature to provide Stokes parameter estimations for spatially varying scenes using polarization gratings. However, the demonstrated system does not employ aggressive modulation frequencies to take full advantage of the bandwidth available to the focal plane array. A snapshot imaging Stokes polarimeter is described and demonstrated through results. The simulation studies the challenges of using a maximum bandwidth configuration for a snapshot polarization grating based polarimeter, such as the fringe contrast attenuation that results from higher modulation frequencies. Similar simulation results are generated and compared for a microgrid polarimeter. Microgrid polarimeters are instruments where pixelated polarizers are superimposed onto a focal plan array, and this is another type of spatially modulated polarimeter, and the most common design uses a 2x2 super pixel of polarizers which maximally uses the available bandwidth of the focal plane array.

  3. Correlation and image compression for limited-bandwidth CCD.

    SciTech Connect

    Thompson, Douglas G.

    2005-07-01

    As radars move to Unmanned Aerial Vehicles with limited-bandwidth data downlinks, the amount of data stored and transmitted with each image becomes more significant. This document gives the results of a study to determine the effect of lossy compression in the image magnitude and phase on Coherent Change Detection (CCD). We examine 44 lossy compression types, plus lossless zlib compression, and test each compression method with over 600 CCD image pairs. We also derive theoretical predictions for the correlation for most of these compression schemes, which compare favorably with the experimental results. We recommend image transmission formats for limited-bandwidth programs having various requirements for CCD, including programs which cannot allow performance degradation and those which have stricter bandwidth requirements at the expense of CCD performance.

  4. Paediatric endoscopy by adult gastroenterologists in Ile-Ife, Nigeria: A viable option to increase the access to paediatric endoscopy in low resource countries

    PubMed Central

    Alatise, Olusegun I.; Anyabolu, Henry Chineme; Sowande, Oludayo; Akinola, David

    2015-01-01

    Background: Paediatric endoscopy performed by adult gastroenterologists is a service delivery model that increases the access of children to endoscopy in countries where paediatric gastroenterologists with endoscopy skills are scarce. However, studies on the usefulness of this model in Nigeria and Sub-Saharan Africa are scarce. We aimed to evaluate the indications, procedures, diagnostic yield and safety of paediatric endoscopy performed by adult gastroenterologists in a Nigerian tertiary health facility. Materials and Methods: It was a retrospective study that evaluated the records of paediatric (≤18 years old) endoscopies carried out in the endoscopy suite of Obafemi Awolowo University Teaching Hospital Complex Ile-Ife, Nigeria from January 2007 to December 2014. Results: A total of 63 procedures were successfully completed in children of whom 4 were repeat procedures which were excluded. Thus, 59 endoscopies performed on children were analysed. Most (49; 83.1%) of these procedures on the children were diagnostic with oesophagogastroduodenoscopy being the commonest (43; 72.9%). Epigastric pain (22; 37.3%), haematemesis (17; 28.8%) and dysphagia (9; 15.3%) were the predominant indication for upper gastrointestinal (GI) endoscopy while haematochezia (9; 15.3%) and rectal protrusion (2; 3.4%) were the indications for colonoscopy. Injection sclerotherapy (3; 5.1%) and variceal banding (2; 3.4%) were the therapeutic upper GI endoscopic procedures conducted while polypectomies were performed during colonoscopy in 5 children (8.5%). Abnormal endoscopy findings were observed in 53 out of the 59 children making the positive diagnostic yield to be 89.8%. No complication, either from the procedure or anaesthesia was observed. Conclusion: Paediatric endoscopy performed by adult gastroenterologists is useful, feasible and safe. It is being encouraged as a viable option to fill the gap created by dearth of skilled paediatric gastroenterologists. PMID:26712292

  5. The Change4Life Convenience Store Programme to Increase Retail Access to Fresh Fruit and Vegetables: A Mixed Methods Process Evaluation

    PubMed Central

    Adams, Jean; Halligan, Joel; Burges Watson, Duika; Ryan, Vicky; Penn, Linda; Adamson, Ashley J.; White, Martin

    2012-01-01

    Background Consumption of fruit and vegetables is important for health, but is often lower than recommended and tends to be socio-economically patterned with lower consumption in more deprived groups. In 2008, the English Department of Health introduced the Change4Life convenience store programme. This aimed to increase retail access to fresh fruit and vegetables in deprived, urban areas by providing existing convenience stores with a range of support and branded point-of-sale materials and equipment. Methods We undertook a mixed-methods study of the Change4Life convenience store programme in the North East of England around two years after initial implementation. Store mapping (n = 87; 100% stores) and systematic in-store observations (n = 74; 85% stores) provided information on intervention fidelity; the variety, purchase price and quality of fresh fruit and vegetables on sale; and purchase price compared to a major supermarket. Ten qualitative interviews with a purposive sample of retailers and other professionals explored experiences of the intervention and provided further insight on quantitative results. Results Intervention stores were primarily located in socio-economically disadvantaged areas. Fidelity, in terms of presence of branded materials and equipment, was low and much was not being used as intended. Fresh fruit and vegetables on sale were of high quality and had a purchase price around 10% more than comparable products at a major supermarket. Interviewees were supportive of the health improvement aim of the intervention. Retailers were appreciative of part-funding for chill cabinets and free point-of-sale materials. The intervention suffered from: poor initial and on-going communication between the intervention delivery team and retailers; poor availability of replacement point-of-sale materials; and failure to cement intended links with health workers and community organisations. Conclusions Overall, intervention fidelity was low and the

  6. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOEpatents

    Payne, Stephen A.; Hayden, Joseph S.

    1997-01-01

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P.sub.2 O.sub.5, Al.sub.2 O.sub.3 and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules.

  7. Programmable bandwidth management in software-defined EPON architecture

    NASA Astrophysics Data System (ADS)

    Li, Chengjun; Guo, Wei; Wang, Wei; Hu, Weisheng; Xia, Ming

    2016-07-01

    This paper proposes a software-defined EPON architecture which replaces the hardware-implemented DBA module with reprogrammable DBA module. The DBA module allows pluggable bandwidth allocation algorithms among multiple ONUs adaptive to traffic profiles and network states. We also introduce a bandwidth management scheme executed at the controller to manage the customized DBA algorithms for all date queues of ONUs. Our performance investigation verifies the effectiveness of this new EPON architecture, and numerical results show that software-defined EPONs can achieve less traffic delay and provide better support to service differentiation in comparison with traditional EPONs.

  8. Effective Actuation: High Bandwidth Actuators and Actuator Scaling Laws

    DTIC Science & Technology

    2007-11-02

    5c. PROGRAM ELEMENT NUMBER I-ioh Bandwidth Actiintorv and Actuator 9clinp Iaw-, 65502F 6. AUTHOR(S) 5d. PROJECT NUMBER A. B. Cain, G. R. Raman , and E...of possible applications include the high frequency excitation for supprc~sion of flow induced resonance in weapons bay cavities (see Raman et al...systems. Adaptive high bandwidth actuators are required to adapt to changes in flow speed and conditions during flight. Raman et al. (2000) and Stanek et

  9. Ultrafast pulsed laser utilizing broad bandwidth laser glass

    DOEpatents

    Payne, S.A.; Hayden, J.S.

    1997-09-02

    An ultrafast laser uses a Nd-doped phosphate laser glass characterized by a particularly broad emission bandwidth to generate the shortest possible output pulses. The laser glass is composed primarily of P{sub 2}O{sub 5}, Al{sub 2}O{sub 3} and MgO, and possesses physical and thermal properties that are compatible with standard melting and manufacturing methods. The broad bandwidth laser glass can be used in modelocked oscillators as well as in amplifier modules. 7 figs.

  10. WE-A-16A-01: International Medical Physics Symposium: Increasing Access to Medical Physics Education/Training and Research Excellence

    SciTech Connect

    Bortfeld, T; Ngoma, T; Odedina, F; Morgan, S; Wu, R; Sajo, E; Ngwa, W

    2014-06-15

    In response to a world in which cancer is a growing global health challenge, there is now a greater need for US Medical Physicists and other Radiation Oncology professionals across institutions to work together and be more globally engaged in the fight against cancer. There are currently many opportunities for Medical Physicists to contribute to alleviating this pressing need, especially in helping enhance access to Medical Physics Education/training and Research Excellence across international boundaries, particularly for low and middle-income countries (LMIC), which suffer from a drastic shortage of accessible knowledge and quality training programs in radiotherapy. Many Medical Physicists are not aware of the range of opportunities that even with small effort could have a high impact. Faculty at the two CAMPEP-accredited Medical Physics Programs in New England: the University of Massachusetts Lowell and Harvard Medical School have developed a growing alliance to increase Access to Medical Physics Education/training and Research Excellence (AMPERE), and facilitate greater active involvement of U.S. Medical Physicists in helping the global fight against cancer and cancer disparities. In this symposium, AMPERE Alliance members and partners from Europe and Africa will present and discuss the growing global cancer challenge, the dearth of knowledge, research, and other barriers to providing life-saving radiotherapy in LMIC, mechanisms for meeting these challenges, the different opportunities for participation by Medical Physicists, including students and residents, and how participation can be facilitated to increase AMPERE for global health. Learning Objectives: To learn about the growing global cancer challenge, areas of greatest need and limitations to accessing knowledge and quality radiotherapy training programs, especially in LMIC; To learn about the range of opportunities for Medical Physicists, including students and residents, to work together in global

  11. A scheme of pulse compression lidar with enhanced modulated bandwidth for detection through scattering media

    NASA Astrophysics Data System (ADS)

    Yang, Cheng-hua; Zhang, Yong; Jin, Chen-fei; Xu, Lu; Yang, Xu; Wang, Qiang; Liu, Yue-hao; Zhao, Yuan

    2016-12-01

    This paper presents a scheme of pulse compression lidar with enhanced electrical modulated bandwidth. An ultra-wideband linear frequency modulated signal with a bandwidth of 50 GHz is generated using femtosecond laser and superimposed linear chirp fiber Bragg gratings in the transmitter, which separates the echo of the target from the backward scattered noise with low modulated frequency. An optical pulse compression system based on a negative dispersion fiber Bragg grating is used to compress the ultra-wideband linear frequency modulated signal in the receiver. SNR and range resolution of the proposed scheme are numerically simulated to prove its feasibility. The simulation results indicate that an enhancement of SNR by 15.8 dB can be achieved using the scheme, and the range resolution of the scheme increases from 0.68 m to 0.0027 m. It is therefore concluded that the proposed scheme is suitable for detection through scattering media.

  12. Banded all-optical OFDM super-channels with low-bandwidth receivers.

    PubMed

    Song, Binhuang; Zhu, Chen; Corcoran, Bill; Zhuang, Leimeng; Lowery, Arthur James

    2016-08-08

    We propose a banded all-optical orthogonal frequency division multiplexing (AO-OFDM) transmission system based on synthesising a number of truncated sinc-shaped subcarriers for each sub-band. This approach enables sub-band by sub-band reception and therefore each receiver's electrical bandwidth can be significantly reduced compared with a conventional AO-OFDM system. As a proof-of-concept experiment, we synthesise 6 × 10-Gbaud subcarriers in both conventional and banded AO-OFDM systems. With a limited receiver electrical bandwidth, the experimental banded AO-OFDM system shows 2-dB optical signal to noise ratio (OSNR) benefit over conventional AO-OFDM at the 7%-overhead forward error correction (FEC) threshold. After transmission over 800-km of single-mode fiber, ≈3-dB improvement in Q-factor can be achieved at the optimal launch power at a cost of increasing the spectral width by 14%.

  13. Solid-State Laser Source of Tunable Narrow-Bandwidth Ultraviolet Radiation

    NASA Technical Reports Server (NTRS)

    Goldberg, Lew; Kliner, Dahv A.; Koplow, Jeffrey P.

    1998-01-01

    A solid-state laser source of tunable and narrow-bandwidth UV light is disclosed. The system relies on light from a diode laser that preferably generates light at infrared frequencies. The light from the seed diode laser is pulse amplified in a light amplifier, and converted into the ultraviolet by frequency tripling, quadrupling, or quintupling the infrared light. The narrow bandwidth, or relatively pure light, of the seed laser is preserved, and the pulse amplifier generates high peak light powers to increase the efficiency of the nonlinear crystals in the frequency conversion stage. Higher output powers may be obtained by adding a fiber amplifier to power amplify the pulsed laser light prior to conversion.

  14. Magnetoresistive Current Sensors for High Accuracy, High Bandwidth Current Measurement in Spacecraft Power Electronics

    NASA Astrophysics Data System (ADS)

    Slatter, Rolf; Goffin, Benoit

    2014-08-01

    The usage of magnetoresistive (MR) current sensors is increasing steadily in the field of power electronics. Current sensors must not only be accurate and dynamic, but must also be compact and robust. The MR effect is the basis for current sensors with a unique combination of precision and bandwidth in a compact package. A space-qualifiable magnetoresistive current sensor with high accuracy and high bandwidth is being jointly developed by the sensor manufacturer Sensitec and the spacecraft power electronics supplier Thales Alenia Space (T AS) Belgium. Test results for breadboards incorporating commercial-off-the-shelf (COTS) sensors are presented as well as an application example in the electronic control and power unit for the thrust vector actuators of the Ariane5-ME launcher.

  15. Improving Sensitivity and Bandwidth of an Atomic Magnetometer using Quantum Non-Demolition Measurement

    NASA Astrophysics Data System (ADS)

    Shah, Vishal; Vasilakis, Georgios; Romalis, Michael

    2009-05-01

    The fundamental sensitivity of an atomic magnetometer is limited by spin projection noise. In the case of uniform spin relaxation, it is well understood that it is not possible to improve the sensitivity using spin squeezing induced by quantum non-demolition (QND) measurement for measurement time scales longer than spin relaxation time [1, 2]. It is however possible to increase the bandwidth of the magnetometer using QND measurement. Here we experimentally demonstrate, in excellent agreement with the theory, an improvement in the bandwidth of our scalar alkali vapor atomic magnetometer using continuous QND measurement. We also investigate the possibility of improving sensitivity of our magnetometer in the special case in which the spin relaxation is time dependent. The case of time dependent spin relaxation naturally arises in high polarization regime in an alkali-alkali spin-exchange relaxation dominated atomic sample. [1] S. F. Huelga, Phys. Rev. Lett. 79, 3865 -- 3868, 1997. [2] M. Auzinsh, Phys. Rev. Lett. 93, 173002, 2004.

  16. Broad-Bandwidth FPGA-Based Digital Polyphase Spectrometer

    NASA Technical Reports Server (NTRS)

    Jamot, Robert F.; Monroe, Ryan M.

    2012-01-01

    With present concern for ecological sustainability ever increasing, it is desirable to model the composition of Earth s upper atmosphere accurately with regards to certain helpful and harmful chemicals, such as greenhouse gases and ozone. The microwave limb sounder (MLS) is an instrument designed to map the global day-to-day concentrations of key atmospheric constituents continuously. One important component in MLS is the spectrometer, which processes the raw data provided by the receivers into frequency-domain information that cannot only be transmitted more efficiently, but also processed directly once received. The present-generation spectrometer is fully analog. The goal is to include a fully digital spectrometer in the next-generation sensor. In a digital spectrometer, incoming analog data must be converted into a digital format, processed through a Fourier transform, and finally accumulated to reduce the impact of input noise. While the final design will be placed on an application specific integrated circuit (ASIC), the building of these chips is prohibitively expensive. To that end, this design was constructed on a field-programmable gate array (FPGA). A family of state-of-the-art digital Fourier transform spectrometers has been developed, with a combination of high bandwidth and fine resolution. Analog signals consisting of radiation emitted by constituents in planetary atmospheres or galactic sources are downconverted and subsequently digitized by a pair of interleaved analog-to-digital converters (ADCs). This 6-Gsps (gigasample per second) digital representation of the analog signal is then processed through an FPGA-based streaming fast Fourier transform (FFT). Digital spectrometers have many advantages over previously used analog spectrometers, especially in terms of accuracy and resolution, both of which are particularly important for the type of scientific questions to be addressed with next-generation radiometers.

  17. Sensitivity to temporal modulation rate and spectral bandwidth in the human auditory system: MEG evidence.

    PubMed

    Wang, Yadong; Ding, Nai; Ahmar, Nayef; Xiang, Juanjuan; Poeppel, David; Simon, Jonathan Z

    2012-04-01

    Slow acoustic modulations below 20 Hz, of varying bandwidths, are dominant components of speech and many other natural sounds. The dynamic neural representations of these modulations are difficult to study through noninvasive neural-recording methods, however, because of the omnipresent background of slow neural oscillations throughout the brain. We recorded the auditory steady-state responses (aSSR) to slow amplitude modulations (AM) from 14 human subjects using magnetoencephalography. The responses to five AM rates (1.5, 3.5, 7.5, 15.5, and 31.5 Hz) and four types of carrier (pure tone and 1/3-, 2-, and 5-octave pink noise) were investigated. The phase-locked aSSR was detected reliably in all conditions. The response power generally decreases with increasing modulation rate, and the response latency is between 100 and 150 ms for all but the highest rates. Response properties depend only weakly on the bandwidth. Analysis of the complex-valued aSSR magnetic fields in the Fourier domain reveals several neural sources with different response phases. These neural sources of the aSSR, when approximated by a single equivalent current dipole (ECD), are distinct from and medial to the ECD location of the N1m response. These results demonstrate that the globally synchronized activity in the human auditory cortex is phase locked to slow temporal modulations below 30 Hz, and the neural sensitivity decreases with an increasing AM rate, with relative insensitivity to bandwidth.

  18. Browsing for the Best Internet Access Provider?

    ERIC Educational Resources Information Center

    Weil, Marty

    1996-01-01

    Highlights points to consider when choosing an Internet Service Provider. Serial Line Internet Protocol (SLIP) and Point to Point Protocol (PPP) are compared regarding price, performance, bandwidth, speed, and technical support. Obtaining access via local, national, consumer online, and telephone-company providers is discussed. A pricing chart and…

  19. Transportation dynamics on coupled networks with limited bandwidth

    NASA Astrophysics Data System (ADS)

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-12-01

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly.

  20. Transportation dynamics on coupled networks with limited bandwidth.

    PubMed

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-12-14

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly.

  1. Velocity magnitude estimation with linear arrays using Doppler bandwidth.

    PubMed

    Tortoli, P; Guidi, G; Mantovani, L; Newhouse, V L

    2001-04-01

    The dependence of pulsed wave Doppler bandwidth on parameters typical of linear transducer arrays used in commercial Duplex and color flow mapping systems is investigated experimentally. For a single flow line it is observed that this bandwidth generally depends not only on the scatterer velocity and the beam-to-flow angle, but also on the flow line range and orientation. This is due to the fact that in Duplex and color flow systems the transducer is differently focused in the scan and elevation planes and its aperture and focal lengths are often made to vary, depending on the distance of the flow line from the transducer. It is however experimentally demonstrated that, at points where the ultrasound beamwidths in the scan and elevation planes are both comparable to the sample volume length, the Doppler bandwidth is independent of the beam-to-flow angle. It is also shown that this invariance can be extended to other ranges by appropriately modifying the array aperture. Finally, as an application of this independence, the flow-line velocity magnitude in these beam regions is estimated with better than 5% uncertainty through a simple bandwidth measurement.

  2. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or TV booster station authorizes the transmission of the visual signal by amplitude modulation (A5) and...

  3. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or TV booster station authorizes the transmission of the visual signal by amplitude modulation (A5) and...

  4. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or TV booster station authorizes the transmission of the visual signal by amplitude modulation (A5) and...

  5. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or TV booster station authorizes the transmission of the visual signal by amplitude modulation (A5) and...

  6. 47 CFR 74.736 - Emissions and bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ..., AUXILIARY, SPECIAL BROADCAST AND OTHER PROGRAM DISTRIBUTIONAL SERVICES Low Power TV, TV Translator, and TV Booster Stations § 74.736 Emissions and bandwidth. (a) The license of a low power TV, TV translator, or TV booster station authorizes the transmission of the visual signal by amplitude modulation (A5) and...

  7. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Emissions and bandwidth. 101.515 Section 101.515 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions...

  8. Numerical Models of Broad Bandwidth Nanosecond Optical Parametric Oscillators

    SciTech Connect

    Bowers, M.S.; Gehr, R.J.; Smith, A.V.

    1998-10-14

    We describe results from three new methods of numerically modeling broad-bandwidth, nanosecond OPO's in the plane-wave approximate ion. They account for differences in group velocities among the three mixing waves, and also include a qutt~ttun noise model.

  9. Transportation dynamics on coupled networks with limited bandwidth

    PubMed Central

    Li, Ming; Hu, Mao-Bin; Wang, Bing-Hong

    2016-01-01

    The communication networks in real world often couple with each other to save costs, which results in any network does not have a stand-alone function and efficiency. To investigate this, in this paper we propose a transportation model on two coupled networks with bandwidth sharing. We find that the free-flow state and the congestion state can coexist in the two coupled networks, and the free-flow path and congestion path can coexist in each network. Considering three bandwidth-sharing mechanisms, random, assortative and disassortative couplings, we also find that the transportation capacity of the network only depends on the coupling mechanism, and the fraction of coupled links only affects the performance of the system in the congestion state, such as the traveling time. In addition, with assortative coupling, the transportation capacity of the system will decrease significantly. However, the disassortative coupling has little influence on the transportation capacity of the system, which provides a good strategy to save bandwidth. Furthermore, a theoretical method is developed to obtain the bandwidth usage of each link, based on which we can obtain the congestion transition point exactly. PMID:27966624

  10. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Emissions and bandwidth. 101.515 Section 101.515 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions...

  11. 47 CFR 74.535 - Emission and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... reference bandwidth. (2) When using transmissions employing digital modulation techniques: (i) For operating... the transmitter modulates a single carrier, digital modulation techniques are considered as being employed when digital modulation occupies 50 percent or more of the total peak frequency deviation of...

  12. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Emissions and bandwidth. 101.515 Section 101.515 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions...

  13. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Emissions and bandwidth. 101.515 Section 101.515 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions...

  14. 47 CFR 101.515 - Emissions and bandwidth.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Emissions and bandwidth. 101.515 Section 101.515 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES 24 GHz Service and Digital Electronic Message Service § 101.515 Emissions...

  15. Characterizing the effective bandwidth of tri-stable energy harvesters

    NASA Astrophysics Data System (ADS)

    Panyam, Meghashyam; Daqaq, Mohammed F.

    2017-01-01

    Recently, it has been shown that nonlinear vibratory energy harvesters possessing a tri-stable potential function are capable of harvesting energy efficiently over a wider range of frequencies in comparison to harvesters with a double-well potential function. However, the effect of the design parameters of the harvester on the dynamic response and the effective bandwidth of such devices remains uninvestigated. To fill this void, this paper establishes an analytical approach to characterize the effective frequency bandwidth of harvesters that possess a hexic potential energy function. To achieve this goal, the method of multiple scales is utilized to construct analytical solutions describing the amplitude and stability of the intra- and inter-well dynamics of the harvester. Using these solutions, critical bifurcations in the parameter's space are identified and used to define an effective frequency bandwidth of the harvester. The influence of the electric parameters, namely, the time constant ratio (ratio between the period of the mechanical system and the time constant of the harvesting circuit) and the electromechanical coupling, on the effective frequency bandwidth is analyzed. Experimental studies performed on the harvester are presented to validate some of the theoretical findings.

  16. The Learning Computer: Low Bandwidth Tool that Bridges Digital Divide

    ERIC Educational Resources Information Center

    Johnson, Russell; Kemp, Elizabeth; Kemp, Ray; Blakey, Peter

    2007-01-01

    This article reports on a project that explores strategies for narrowing the digital divide by providing a practicable e-learning option for the millions living outside the ambit of high performance computing and communication technology. The concept is introduced of a "learning computer," a low bandwidth tool that provides a simplified,…

  17. Optimizing System Compute and Bandwidth Density for Deployed HPEC Applications

    DTIC Science & Technology

    2007-11-02

    Optimizing System Compute and Bandwidth Density for Deployed HPEC Applications Randy Banton and Richard Jaenicke Mercury Computer Systems, Inc...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Mercury Computer Systems, Inc. 8. PERFORMING ORGANIZATION REPORT NUMBER 9... Mercury Computer Systems, Inc. Optimizing System Compute Density for Deployed HPEC Applications Randy Banton, Director, Defense Electronics Engineering

  18. High-Density, High-Bandwidth, Multilevel Holographic Memory

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    2008-01-01

    A proposed holographic memory system would be capable of storing data at unprecedentedly high density, and its data transfer performance in both reading and writing would be characterized by exceptionally high bandwidth. The capabilities of the proposed system would greatly exceed even those of a state-of-the art memory system, based on binary holograms (in which each pixel value represents 0 or 1), that can hold .1 terabyte of data and can support a reading or writing rate as high as 1 Gb/s. The storage capacity of the state-of-theart system cannot be increased without also increasing the volume and mass of the system. However, in principle, the storage capacity could be increased greatly, without significantly increasing the volume and mass, if multilevel holograms were used instead of binary holograms. For example, a 3-bit (8-level) hologram could store 8 terabytes, or an 8-bit (256-level) hologram could store 256 terabytes, in a system having little or no more size and mass than does the state-of-the-art 1-terabyte binary holographic memory. The proposed system would utilize multilevel holograms. The system would include lasers, imaging lenses and other beam-forming optics, a block photorefractive crystal wherein the holograms would be formed, and two multilevel spatial light modulators in the form of commercially available deformable-mirror-device spatial light modulators (DMDSLMs) made for use in high speed input conversion of data up to 12 bits. For readout, the system would also include two arrays of complementary metal oxide/semiconductor (CMOS) photodetectors matching the spatial light modulators. The system would further include a reference-beam sterring device (equivalent of a scanning mirror), containing no sliding parts, that could be either a liquid-crystal phased-array device or a microscopic mirror actuated by a high-speed microelectromechanical system. Time-multiplexing and the multilevel nature of the DMDSLM would be exploited to enable writing

  19. Fair Scheduling and Throughput Maximization for IEEE 802.16 Mesh Mode Broadband Wireless Access Networks

    NASA Astrophysics Data System (ADS)

    Alam, Muhammad Mahbub; Hamid, Md. Abdul; Razzaque, Md. Abdur; Hong, Choong Seon

    Broadband wireless access networks are promising technology for providing better end user services. For such networks, designing a scheduling algorithm that fairly allocates the available bandwidth to the end users and maximizes the overall network throughput is a challenging task. In this paper, we develop a centralized fair scheduling algorithm for IEEE 802.16 mesh networks that exploits the spatio-temporal bandwidth reuse to further enhance the network throughput. The proposed mechanism reduces the length of a transmission round by increasing the number of non-contending links that can be scheduled simultaneously. We also propose a greedy algorithm that runs in polynomial time. Performance of the proposed algorithms is evaluated by extensive simulations. Results show that our algorithms achieve higher throughput than that of the existing ones and reduce the computational complexity.

  20. Increased Access to Antiretroviral Therapy Is Associated with Reduced Maternal Mortality in Johannesburg, South Africa: An Audit from 2003-2012

    PubMed Central

    Black, Andrew D.; Rees, Helen V.; Guidozzi, Franco; Scorgie, Fiona; Chersich, Matthew F.

    2016-01-01

    Objective To assess the impact of expanded access to antiretroviral treatment (ART) on maternal mortality in Johannesburg, South Africa between 2003 and 2012. Methods Audit of patient files, birth registers and death certificates at a tertiary level referral hospital. Cause of death was assigned independently, by two reviewers. We compared causes of deaths and the maternal mortality ratios (MMR, deaths/100,000 live births) over three periods corresponding to changes in government policy on ART provision: period one, 2003–2004 (pre-ART); period two, 2005–2009 (ART eligibility with CD4 count <200cells/μL or WHO stage 4 disease); and period three, 2010–2012 (eligibility with CD4 count <350 cells/μL). Results There were 232 deaths and 80,376 deliveries in the three periods. The proportion of pregnant women tested for HIV rose from 43.4% in 2003 to 94.6% in 2012. MMR was 301, 327 and 232 in the three periods, (p = 0.10). The third period MMR was lower than the first and second combined (p = 0.03). Among HIV-positive women, the MMR fell from 836 in the first time period to 431 in the third (p = 0.008) but among HIV negative women it remained unchanged over the three periods, averaging 148. Even in the third period, however, the MMR among HIV-infected women was 3-fold higher than in other women. Mortality from direct obstetric causes such as hemorrhage did not decline over time, but deaths from tuberculosis and HIV-associated malignancy did. In 38.3% of deaths, women had not attended antenatal care. Conclusion Higher coverage of HIV testing and ART has substantially reduced MMR in this hospital setting. Though the gap in MMR between women with and without HIV narrowed, a third of deaths still remain attributable to HIV. Lowering overall MMR will require further strengthening of HIV services, increased antenatal care coverage, and improved care for obstetric emergencies at all levels of care. PMID:28033409

  1. Breaking the trade-off: rainforest bats maximize bandwidth and repetition rate of echolocation calls as they approach prey.

    PubMed

    Schmieder, Daniela A; Kingston, Tigga; Hashim, Rosli; Siemers, Björn M

    2010-10-23

    Both mammals and birds experience a performance trade-off between producing vocalizations with high bandwidths and at high repetition rate. Echolocating bats drastically increase repetition rate from 2-20 calls s(-1) up to about 170 calls s(-1) prior to intercepting airborne prey in order to accurately track prey movement. In turn, bandwidth drops to about 10-30 kHz for the calls of this 'final buzz'. We have now discovered that Southeast Asian rainforest bats (in the vespertilionid subfamilies Kerivoulinae and Murininae) are able to maintain high call bandwidths at very high repetition rates throughout approach to prey. Five species of Kerivoula and Phoniscus produced call bandwidths of between 78 and 170 kHz at repetition rates of 140-200 calls s(-1) and two of Murina at 80 calls s(-1). The 'typical' and distinct drop in call frequency was present in none of the seven species. This stands in striking contrast to our present view of echolocation during approach to prey in insectivorous bats, which was established largely based on European and American members of the same bat family, the Vespertilionidae. Buzz calls of Kerivoula pellucida had mean bandwidths of 170 kHz and attained maximum starting frequencies of 250 kHz which makes them the most broadband and most highly pitched tonal animal vocalization known to date. We suggest that the extreme vocal performance of the Kerivoulinae and Murininae evolved as an adaptation to echolocating and tracking arthropods in the dense rainforest understorey.

  2. Sensitivity to temporal modulation rate and spectral bandwidth in the human auditory system: fMRI evidence.

    PubMed

    Overath, Tobias; Zhang, Yue; Sanes, Dan H; Poeppel, David

    2012-04-01

    Hierarchical models of auditory processing often posit that optimal stimuli, i.e., those eliciting a maximal neural response, will increase in bandwidth and decrease in modulation rate as one ascends the auditory neuraxis. Here, we tested how bandwidth and modulation rate interact at several loci along the human central auditory pathway using functional MRI in a cardiac-gated, sparse acquisition design. Participants listened passively to both narrowband (NB) and broadband (BB) carriers (1/4- or 4-octave pink noise), which were jittered about a mean sinusoidal amplitude modulation rate of 0, 3, 29, or 57 Hz. The jittering was introduced to minimize stimulus-specific adaptation. The results revealed a clear difference between spectral bandwidth and temporal modulation rate: sensitivity to bandwidth (BB > NB) decreased from subcortical structures to nonprimary auditory cortex, whereas sensitivity to slow modulation rates was largest in nonprimary auditory cortex and largely absent in subcortical structures. Furthermore, there was no parametric interaction between bandwidth and modulation rate. These results challenge simple hierarchical models, in that BB stimuli evoked stronger responses in primary auditory cortex (and subcortical structures) rather than nonprimary cortex. Furthermore, the strong preference for slow modulation rates in nonprimary cortex demonstrates the compelling global sensitivity of auditory cortex to modulation rates that are dominant in the principal signals that we process, e.g., speech.

  3. A Quasi-Experimental Evaluation of Parents as Sexual Health Educators Resulting in Delayed Sexual Initiation and Increased Access to Condoms

    ERIC Educational Resources Information Center

    Campero, Lourdes; Walker, Dilys; Atienzo, Erika E.; Gutierrez, Juan Pablo

    2011-01-01

    Objective: To evaluate the effectiveness of an educational intervention for parents of first year high school students in the State of Morelos, Mexico, whose aim was to impact adolescents' sexual behavior, knowledge and access to contraception. Material and methods: Quasi-experimental prospective study with eleven control and eleven intervention…

  4. [Accessible Rural Housing.

    ERIC Educational Resources Information Center

    Baker, Nick, Ed.

    1995-01-01

    This issue of the quarterly newsletter "Rural Exchange" provides information and resources on accessible rural housing for the disabled. "Accessible Manufactured Housing Could Increase Rural Home Supply" (Nick Baker) suggests that incorporation of access features such as lever door handles and no-step entries into manufactured housing could help…

  5. Bandpass filter with adjustable bandwidth based on a press-induced long-period twisted holey-fiber grating.

    PubMed

    Torres-Gómez, I; Martínez-Ríos, A; Ceballos-Herrera, D E; Mejía-Beltrán, E; Selvas-Aguilar, R

    2007-12-01

    A bandpass filter with adjustable bandwidth based on a press-induced long-period grating in a twisted holey fiber is presented. By twisting the holey fiber prior to the application of periodic pressure, each rejection band of the nontwisted induced long-period grating is split into two shifted rejection bands that move further apart as the twist ratio increases. This feature results in a wide bandpass filter with controllable bandwidth. A bandpass filter at 1523 nm with adjustable bandwidth from 15 to 65 nm with near-linear response and insertion loss lower than 0.7 dB is demonstrated. Additionally, the bandpass filter can be tuned over 100 nm.

  6. Balancing high gain and bandwidth in multilayer organic photodetectors with tailored carrier blocking layers

    NASA Astrophysics Data System (ADS)

    Hammond, William T.; Mudrick, John P.; Xue, Jiangeng

    2014-12-01

    We present detailed studies of the high photocurrent gain behavior in multilayer organic photodiodes containing tailored carrier blocking layers we reported earlier in a Letter [W. T. Hammond and J. Xue, Appl. Phys. Lett. 97, 073302 (2010)], in which a high photocurrent gain of up to 500 was attributed to the accumulation of photogenerated holes at the anode/organic active layer interface and the subsequent drastic increase in secondary electron injection from the anode. Here, we show that both the hole-blocking layer structure and layer thickness strongly influence the magnitude of the photocurrent gain. Temporal studies revealed that the frequency response of such devices is limited by three different processes with lifetimes of 10 μs, 202 μs, and 2.72 ms for the removal of confined holes, which limit the 3 dB bandwidth of these devices to 1.4 kHz. Furthermore, the composition in the mixed organic donor-acceptor photoactive layer affects both gain and bandwidth, which is attributed to the varying charge transport characteristics, and the optimal gain-bandwidth product is achieved with approximately 30% donor content. Finally, these devices show a high dynamic range of more than seven orders of magnitude, although the photocurrent shows a sublinear dependence on the incident optical power.

  7. Fabrication of a 2-DOF electromagnetic energy harvester with in-phase vibrational bandwidth broadening

    NASA Astrophysics Data System (ADS)

    Chen, Shih-Jui; Wu, Jia-Yin

    2016-09-01

    A vibration structure with two-degrees-of-freedom is proposed to increase the usable bandwidth of a micromachined electromagnetic energy harvester. Compared with the structure of a pure cantilever harvester, the proposed structure is formed by integrating a spiral diaphragm into a U-shaped cantilever diaphragm. By performing finite element analysis, the resonance frequencies of the two diaphragms are designed with a slight shift, both lower than 300 Hz. In addition, to achieve output bandwidth broadening, electroplated copper coils on the spiral and the U-shaped cantilever are coupled and the connection sequences of the coupled coils are arranged such that single- or duo-mode tuning of the energy harvester can be realized. The harvester delivers powers of 22.1 and 21.5 nW at two resonance frequencies of 211 and 274 Hz, respectively, in the duo-mode operation. The proposed spiral-cantilever coupled energy harvester has lower resonance frequencies and broader bandwidth than a pure cantilever-type harvester of equal area, and can therefore harvest more energy from the environment.

  8. Balancing high gain and bandwidth in multilayer organic photodetectors with tailored carrier blocking layers

    SciTech Connect

    Hammond, William T.; Mudrick, John P.; Xue, Jiangeng

    2014-12-07

    We present detailed studies of the high photocurrent gain behavior in multilayer organic photodiodes containing tailored carrier blocking layers we reported earlier in a Letter [W. T. Hammond and J. Xue, Appl. Phys. Lett. 97, 073302 (2010)], in which a high photocurrent gain of up to 500 was attributed to the accumulation of photogenerated holes at the anode/organic active layer interface and the subsequent drastic increase in secondary electron injection from the anode. Here, we show that both the hole-blocking layer structure and layer thickness strongly influence the magnitude of the photocurrent gain. Temporal studies revealed that the frequency response of such devices is limited by three different processes with lifetimes of 10 μs, 202 μs, and 2.72 ms for the removal of confined holes, which limit the 3 dB bandwidth of these devices to 1.4 kHz. Furthermore, the composition in the mixed organic donor-acceptor photoactive layer affects both gain and bandwidth, which is attributed to the varying charge transport characteristics, and the optimal gain-bandwidth product is achieved with approximately 30% donor content. Finally, these devices show a high dynamic range of more than seven orders of magnitude, although the photocurrent shows a sublinear dependence on the incident optical power.

  9. Effect of pumping delay on the modulation bandwidth in double tunneling-injection quantum dot lasers.

    PubMed

    Asryan, Levon V

    2017-01-01

    The modulation bandwidth of double tunneling-injection (DTI) quantum dot (QD) lasers is studied, taking into account noninstantaneous pumping of QDs. In this advanced type of semiconductor lasers, carriers are first captured from the bulk waveguide region into two-dimensional regions (quantum wells [QWs]); then they tunnel from the QWs into zero-dimensional regions (QDs). The two processes are noninstantaneous and, thus, could delay the delivery of the carriers to the QDs. Here, the modulation bandwidth of DTI QD lasers is calculated as a function of two characteristic times (the capture time from the waveguide region into the QW and the tunneling time from the QW into the QD ensemble) and is shown to increase as either of these times is reduced. The capture and tunneling times of 1 and 0.1 ps, respectively, are shown to characterize fast capture and tunneling processes; as the capture and tunneling times are brought below 1 and 0.1 ps, the bandwidth remains almost unchanged and close to its upper limit.

  10. Tri-material multilayer coatings with high reflectivity and wide bandwidth for 25 to 50 nm extreme ultraviolet light

    SciTech Connect

    Aquila, Andrew; Salmassi, Farhad; Liu, Yanwei; Gullikson, Eric M.

    2009-09-09

    Magnesium/silicon carbide (Mg/SiC) multilayers have been fabricated with normal incidence reflectivity in the vicinity of 40% to 50% for wavelengths in the 25 to 50 nm wavelength range. However many applications, for example solar telescopes and ultrafast studies using high harmonic generation sources, desire larger bandwidths than provided by high reflectivity Mg/SiC multilayers. We investigate introducing a third material, Scandium, to create a tri-material Mg/Sc/SiC multilayer allowing an increase the bandwidth while maintaining high reflectivity.

  11. A system-level bandwidth design method for wormhole network-on-chip

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Li, Yubai; Liao, Changjun

    2016-11-01

    To improve the Network-on-Chip (NoC) performance, we propose a system-level bandwidth design method customising the bandwidths of the NoC links. In details, we first built a mathematical model to catch the relationship between the NoC commutation latency and the NoC link bandwidth, and then develop a bandwidth allocation algorithm to automatically optimise the bandwidth for each NoC link. The experimental results show that our bandwidth-customising method improves the NoC performance compared to the traditional uniform bandwidth allocation method. Besides, it can also make our NoC to achieve the same communication performance level as the uniform bandwidth NoC but using fewer bandwidth resources, which is beneficial to save the NoC area and power.

  12. Critical bandwidth and consonance: their operational definitions in relation to cochlear nonlinearity and combination tones.

    PubMed

    Greenwood, D D

    1991-08-01

    A recent paper (Greenwood, 1990) reviewed cochlear coordinates in several species in relation to empirical frequency-position functions (Greenwood, 1961b, 1974b), one of which well fits the Békésy-Skarstein human cochlear map (Békésy, 1960; Kringlebotn et al, 1979). This increased the independence of the human function from the psychoacoustic data originally used to construct it and encouraged a second assessment of the relations of similar psychoacoustically significant bandwidths to distance and position on the cochlear map. The companion paper (Greenwood, 1991, this issue), found that, among such bandwidths, 'classical' critical bandwidth, and also 'constant interval', estimates in man correspond to equal distances to a closer extent than generally recognized, and over large parts of the frequency range they conform also to an exponential function of distance, as do most of the ERB estimates. This correspondence to almost constant and similar distances facilitates, and forms a part of, an explanation of the operational definitions of critical bandwidth in different experiments. The present account recapitulates the basic explanation of critical bandwidth and consonance offered in Greenwood (1971, 1972b, 1973b, 1974b) and Greenwood et al. (1976): by adding schematic details to the earlier account of critical bandwidth measurements in pure tone masking (the masker-notch interval), two-tone masking, narrow-band masking, and two-tone dissonance-consonance judgements and by outlining its applicability to AM and Quasi-FM detection and to two-band (nominally notched-noise) masking experiments. The measured bandwidths derive from approximately uniform dimensions of traveling wave envelopes in the peak region and from the effects of the resulting spatial pattern of nonlinear interference among primary components. In this account, critical bandwidth in man corresponds to a distance of about 1 or 1.25 mm, depending upon the direction the interval projects from the

  13. Facilitating access to the renal transplant waiting list does not increase the number of transplantations: comparative study of two French regions

    PubMed Central

    Vigneau, Cécile; Laurent, Annelen; Lebbah, Saïd; Le Meur, Nolwenn; Jais, Jean-Philippe; Daugas, Eric; Bayat, Sahar

    2016-01-01

    Background In France, there are important regional disparities of access to the renal transplant waiting list and transplantation. Our objectives were to compare the characteristics of patients with end-stage renal disease (ESRD) of two French regions (Ile-de-France and Bretagne) and to identify determinants of access to the waiting list and subsequent transplantation, with a focus on temporary inactive status (TIS) periods. Methods All 18–80-year-old incident patients who started dialysis in Ile-de-France or Bretagne between 2006 and 2009 were included (n = 6160). Associations between patients' characteristics and placement on the waiting list or transplantation were assessed using a Fine and Gray model to take into account the competing risk of death and living donor transplantation. Results At the end of the follow-up (31 December 2013), more patients had undergone transplantation in Bretagne than in Ile-de-France (30 versus 27%), although the percentage of waitlisted patients was higher in Ile-de-France than in Bretagne (47 versus 33%). More patients were on TIS and with a longer median TIS duration in Ile-de-France. Independent of age and clinical characteristics, patients in Bretagne were less likely to be waitlisted than those in Ile-de-France [subdistribution hazard ratio 0.77 (95% confidence interval 0.7–0.9)]. After waitlisting, patients in Bretagne were four times more likely to be transplanted. Conclusions Our study highlights clinical practice differences in Bretagne and Ile-de-France and shows that facilitating access to the waiting list is not sufficient to improve access to renal transplantation, which also depends on organ availability. PMID:27994866

  14. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    NASA Astrophysics Data System (ADS)

    Dykstra, D.; Bockelman, B.; Blomer, J.; Herner, K.; Levshina, T.; Slyz, M.

    2015-12-01

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called "alien cache" to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached locally on the

  15. Engineering the CernVM-Filesystem as a High Bandwidth Distributed Filesystem for Auxiliary Physics Data

    SciTech Connect

    Dykstra, D.; Bockelman, B.; Blomer, J.; Herner, K.; Levshina, T.; Slyz, M.

    2015-12-23

    A common use pattern in the computing models of particle physics experiments is running many distributed applications that read from a shared set of data files. We refer to this data is auxiliary data, to distinguish it from (a) event data from the detector (which tends to be different for every job), and (b) conditions data about the detector (which tends to be the same for each job in a batch of jobs). Relatively speaking, conditions data also tends to be relatively small per job where both event data and auxiliary data are larger per job. Unlike event data, auxiliary data comes from a limited working set of shared files. Since there is spatial locality of the auxiliary data access, the use case appears to be identical to that of the CernVM- Filesystem (CVMFS). However, we show that distributing auxiliary data through CVMFS causes the existing CVMFS infrastructure to perform poorly. We utilize a CVMFS client feature called 'alien cache' to cache data on existing local high-bandwidth data servers that were engineered for storing event data. This cache is shared between the worker nodes at a site and replaces caching CVMFS files on both the worker node local disks and on the site's local squids. We have tested this alien cache with the dCache NFSv4.1 interface, Lustre, and the Hadoop Distributed File System (HDFS) FUSE interface, and measured performance. In addition, we use high-bandwidth data servers at central sites to perform the CVMFS Stratum 1 function instead of the low-bandwidth web servers deployed for the CVMFS software distribution function. We have tested this using the dCache HTTP interface. As a result, we have a design for an end-to-end high-bandwidth distributed caching read-only filesystem, using existing client software already widely deployed to grid worker nodes and existing file servers already widely installed at grid sites. Files are published in a central place and are soon available on demand throughout the grid and cached locally on the

  16. Design and Analysis of the LIFG Filters for Coupling Efficiency Near 100 % Range for a Desired Bandwidth

    NASA Astrophysics Data System (ADS)

    Mahmoudzadeh, Ahad

    2016-12-01

    In this paper, we present preliminary simulation results of an improved dual grating-assisted fiber filter. As choosing optimum length the total loss is reduced, and coupling efficiency significantly increased compared to the previously reported results. The coupling efficiency is near 100 % range for a desired bandwidth. Dependence of the coupler on period has also been investigated.

  17. The TSU Streaming Video Astronomy Course - II, Video Interface Design and Bandwidth Considerations

    NASA Astrophysics Data System (ADS)

    Burks, G. S.; Smith, W.

    2004-12-01

    Researchers are developing an on-line video astronomy course at Tennessee State University. Many factors are taken into account when designing a first year course for a broad audience. The initial target audience is students attending historically black colleges and universities, tribal colleges, and other minority institutions, without an astronomy course. The primary goal is to attract students into a course of study that could prepare them to enter the NASA workforce. A secondary goal is to serve the general student population. The question we try to address here is: How can we deliver the video components of such a course in a way that will take into account the innate learning styles of most students and the limited access to very high speed internet lines in smaller colleges? The design for the video information interface will be discussed. The effect of limited bandwidth on video size and other features of the presentation design is also analyzed.

  18. World Wide Access: Accessible Web Design.

    ERIC Educational Resources Information Center

    Washington Univ., Seattle.

    This brief paper considers the application of "universal design" principles to Web page design in order to increase accessibility for people with disabilities. Suggestions are based on the World Wide Web Consortium's accessibility initiative, which has proposed guidelines for all Web authors and federal government standards. Seven guidelines for…

  19. Long-pulse-width narrow-bandwidth solid state laser

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd A.

    1997-01-01

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications.

  20. Long-pulse-width narrow-bandwidth solid state laser

    DOEpatents

    Dane, C.B.; Hackel, L.A.

    1997-11-18

    A long pulse laser system emits 500-1000 ns quasi-rectangular pulses at 527 nm with near diffraction-limited divergence and near transform-limited bandwidth. The system consists of one or more flashlamp-pumped Nd:glass zig-zag amplifiers, a very low threshold stimulated-Brillouin-scattering (SBS) phase conjugator system, and a free-running single frequency Nd:YLF master oscillator. Completely passive polarization switching provides eight amplifier gain passes. Multiple frequency output can be generated by using SBS cells having different pressures of a gaseous SBS medium or different SBS materials. This long pulse, low divergence, narrow-bandwidth, multi-frequency output laser system is ideally suited for use as an illuminator for long range speckle imaging applications. Because of its high average power and high beam quality, this system has application in any process which would benefit from a long pulse format, including material processing and medical applications. 5 figs.

  1. Bandwidth efficient block codes for M-ary PSK modulation

    NASA Technical Reports Server (NTRS)

    Lin, Shu

    1987-01-01

    A class of bandwidth efficient block codes for M-ary PSK modulation is presented. A soft-decision decoding for this class of codes is devised. Some specific short codes for Quad Phase Shift Key (QPSK), 8-PSK and 16-PSK modulations are constructed. These codes have good minimum squared Euclidean distances and provide 2 to 5.8 dB coding gains over uncoded QPSK modulation without (or with little) bandwidth expansion. The complete weight distributions of these specific codes are determined. Based on these weight distributions, their error probabilities are evaluated. Some of these codes have simple trellis structures and hence can be decoded by Viterbi decoding algorithm with relatively simple implementation. Moreover, the codes are very suitable for use as inner codes for various cascaded coding schemes with Reed-Solomon codes as outer codes.

  2. An Adaptive Memory Interface Controller for Improving Bandwidth Utilization of Hybrid and Reconfigurable Systems

    SciTech Connect

    Castellana, Vito G.; Tumeo, Antonino; Ferrandi, Fabrizio

    2014-05-30

    Emerging applications such as data mining, bioinformatics, knowledge discovery, social network analysis are irregular. They use data structures based on pointers or linked lists, such as graphs, unbalanced trees or unstructures grids, which generates unpredictable memory accesses. These data structures usually are large, but difficult to partition. These applications mostly are memory bandwidth bounded and have high synchronization intensity. However, they also have large amounts of inherent dynamic parallelism, because they potentially perform a task for each one of the element they are exploring. Several efforts are looking at accelerating these applications on hybrid architectures, which integrate general purpose processors with reconfigurable devices. Some solutions, which demonstrated significant speedups, include custom-hand tuned accelerators or even full processor architectures on the reconfigurable logic. In this paper we present an approach for the automatic synthesis of accelerators from C, targeted at irregular applications. In contrast to typical High Level Synthesis paradigms, which construct a centralized Finite State Machine, our approach generates dynamically scheduled hardware components. While parallelism exploitation in typical HLS-generated accelerators is usually bound within a single execution flow, our solution allows concurrently running multiple execution flow, thus also exploiting the coarser grain task parallelism of irregular applications. Our approach supports multiple, multi-ported and distributed memories, and atomic memory operations. Its main objective is parallelizing as many memory operations as possible, independently from their execution time, to maximize the memory bandwidth utilization. This significantly differs from current HLS flows, which usually consider a single memory port and require precise scheduling of memory operations. A key innovation of our approach is the generation of a memory interface controller, which

  3. Arteriovenous Access

    PubMed Central

    MacRae, Jennifer M.; Dipchand, Christine; Oliver, Matthew; Moist, Louise; Yilmaz, Serdar; Lok, Charmaine; Leung, Kelvin; Clark, Edward; Hiremath, Swapnil; Kappel, Joanne; Kiaii, Mercedeh; Luscombe, Rick; Miller, Lisa M.

    2016-01-01

    Complications of vascular access lead to morbidity and may reduce quality of life. In this module, we review both infectious and noninfectious arteriovenous access complications including neuropathy, aneurysm, and high-output access. For the challenging patients who have developed many complications and are now nearing their last vascular access, we highlight some potentially novel approaches. PMID:28270919

  4. Ultra-high bandwidth quantum secured data transmission

    NASA Astrophysics Data System (ADS)

    Dynes, James F.; Tam, Winci W.-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-10-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

  5. Adaptive bandwidth measurements of importance functions for speech intelligibility prediction.

    PubMed

    Whitmal, Nathaniel A; DeRoy, Kristina

    2011-12-01

    The Articulation Index (AI) and Speech Intelligibility Index (SII) predict intelligibility scores from measurements of speech and hearing parameters. One component in the prediction is the "importance function," a weighting function that characterizes contributions of particular spectral regions of speech to speech intelligibility. Previous work with SII predictions for hearing-impaired subjects suggests that prediction accuracy might improve if importance functions for individual subjects were available. Unfortunately, previous importance function measurements have required extensive intelligibility testing with groups of subjects, using speech processed by various fixed-bandwidth low-pass and high-pass filters. A more efficient approach appropriate to individual subjects is desired. The purpose of this study was to evaluate the feasibility of measuring importance functions for individual subjects with adaptive-bandwidth filters. In two experiments, ten subjects with normal-hearing listened to vowel-consonant-vowel (VCV) nonsense words processed by low-pass and high-pass filters whose bandwidths were varied adaptively to produce specified performance levels in accordance with the transformed up-down rules of Levitt [(1971). J. Acoust. Soc. Am. 49, 467-477]. Local linear psychometric functions were fit to resulting data and used to generate an importance function for VCV words. Results indicate that the adaptive method is reliable and efficient, and produces importance function data consistent with that of the corresponding AI/SII importance function.

  6. Ultra-high bandwidth quantum secured data transmission.

    PubMed

    Dynes, James F; Tam, Winci W-S; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J

    2016-10-13

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment.

  7. Ultra-high bandwidth quantum secured data transmission

    PubMed Central

    Dynes, James F.; Tam, Winci W-S.; Plews, Alan; Fröhlich, Bernd; Sharpe, Andrew W.; Lucamarini, Marco; Yuan, Zhiliang; Radig, Christian; Straw, Andrew; Edwards, Tim; Shields, Andrew J.

    2016-01-01

    Quantum key distribution (QKD) provides an attractive means for securing communications in optical fibre networks. However, deployment of the technology has been hampered by the frequent need for dedicated dark fibres to segregate the very weak quantum signals from conventional traffic. Up until now the coexistence of QKD with data has been limited to bandwidths that are orders of magnitude below those commonly employed in fibre optic communication networks. Using an optimised wavelength divisional multiplexing scheme, we transport QKD and the prevalent 100 Gb/s data format in the forward direction over the same fibre for the first time. We show a full quantum encryption system operating with a bandwidth of 200 Gb/s over a 100 km fibre. Exploring the ultimate limits of the technology by experimental measurements of the Raman noise, we demonstrate it is feasible to combine QKD with 10 Tb/s of data over a 50 km link. These results suggest it will be possible to integrate QKD and other quantum photonic technologies into high bandwidth data communication infrastructures, thereby allowing their widespread deployment. PMID:27734921

  8. Quantum gates with optimal bandwidth in noisy environments

    NASA Astrophysics Data System (ADS)

    Low, Guang Hao; Theodore, Yoder; Chuang, Isaac

    The traditional approach of open-loop quantum error correction suppresses certain systematic imperfections ɛ in quantum control to higher orders ɛ  (L) by a well-designed sequence of L imperfect quantum gates. However, this philosophy of maximal flatness leads to an ɛ-bandwidth that scales poorly with length and a residual that is easily overwhelmed by unaccounted sources of noise. We advance the paradigm of equiripple compensated gates that directly optimize for bandwidth given the limitations imposed by noise of magnitude δ, leading to dramatically improved performance. Where ɛ represent amplitude errors, we provide a formalism that generalizes both approaches and is effective at finding such gates. With it, we provide in closed-form the phase angles for an optimal family of population inversion gates with an ɛ -bandwidth of  (logδ-1/L) - a quadratic improvement over optimal maximally flat variants. We also construct optimal NOT gates and discuss extensions to other gates and error models.

  9. Multiple access capacity trade-offs for a Ka-band personal access satellite system

    NASA Technical Reports Server (NTRS)

    Dessouky, Khaled; Motamedi, Masoud

    1990-01-01

    System capability is critical to the economic viability of a personal satellite communication system. Ka band has significant potential to support a high capacity multiple access system because of the availability of bandwidth. System design tradeoffs are performed and multiple access schemes are compared with the design goal of achieving the highest capacity and efficiency. Conclusions regarding the efficiency of the different schemes and the achievable capacities are given.

  10. Increasing Public Access to Scientific Research through Stakeholder Involvement: Ecological Effects of Sea Level Rise in the Northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Hagen, S. C.; Stephens, S. H.; DeLorme, D. E.; Ruple, D.; Graham, L.

    2013-12-01

    Sea level rise (SLR) has the potential to have a myriad of deleterious effects on coastal ecology and human infrastructure. Stakeholders, including managers of coastal resources, must be aware of potential consequences of SLR and adjust their plans accordingly to protect and preserve the resources under their care. Members of the public, particularly those who live or work in coastal areas, should also be informed about the results of scientific research on the effects of SLR. However, research results are frequently published in venues or formats to which resource managers and the broader public have limited access. It is imperative for scientists to move beyond traditional publication venues in order to more effectively disseminate the results of their research (Dennison, W. 2007, Estu. Coast. Shelf Sci. 77, 185). One potentially effective way to advance public access to research is to incorporate stakeholder involvement into the research project process in order to target study objectives and tailor communication products toward stakeholder needs (Lemos, M. & Morehouse, B. 2005, Glob. Env. Chg. 15, 57). However, it is important to manage communication and clarify participant expectations during this type of research (Gawith, M. et al. 2009, Glob. Env. Chg. 19, 113). This presentation describes the process being undertaken by an ongoing 5-year multi-disciplinary NOAA-funded project, Ecological Effects of Sea Level Rise in the Northern Gulf of Mexico (EESLR-NGOM), to improve accessibility and utility of scientific research results through stakeholder engagement. The EESLR-NGOM project is assessing the ecological risks from SLR along the Mississippi, Alabama and Florida Panhandle coasts, coastal habitats, and floodplains. It has incorporated stakeholder involvement throughout the research process so as to better target and tailor the emerging research products to meet resource managers' needs, as well as to facilitate eventual public dissemination of results. An

  11. Note: Seesaw actuation of atomic force microscope probes for improved imaging bandwidth and displacement range

    SciTech Connect

    Torun, H.; Torello, D.; Degertekin, F. L.

    2011-08-15

    The authors describe a method of actuation for atomic force microscope (AFM) probes to improve imaging speed and displacement range simultaneously. Unlike conventional piezoelectric tube actuation, the proposed method involves a lever and fulcrum ''seesaw'' like actuation mechanism that uses a small, fast piezoelectric transducer. The lever arm of the seesaw mechanism increases the apparent displacement range by an adjustable gain factor, overcoming the standard tradeoff between imaging speed and displacement range. Experimental characterization of a cantilever holder implementing the method is provided together with comparative line scans obtained with contact mode imaging. An imaging bandwidth of 30 kHz in air with the current setup was demonstrated.

  12. High-contrast, large optical bandwidth field-induced guide/antiguide modulator

    NASA Technical Reports Server (NTRS)

    Huang, T. C.; Chung, Y.; Dagli, N.; Coldren, L. A.

    1991-01-01

    An electric field induced-guide/antiguide optical intensity modulator which has a very wide optical bandwidth from 1 to 1.55/micron which is the largest ever reported before for an intensity modulator. A TE mode ON/OFF ratio larger than 21 dB at 1.15 micron, and a propagation loss about 1 dB at 1.3 micron has been measured. The electrooptic effects, along with carrier effects have been exploited to increase the refractive index under the guide and adjacent antiguide electrodes by applying reverse biases to them.

  13. Neural Networks for the Calculation of Bandwidth of Rectangular Microstrip Antennas

    DTIC Science & Technology

    2003-07-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP014210 TITLE: Neural Networks for the Calculation of Bandwidth of...NO. 2, JULY 2003, SI: NEURAL NETWORK APPLICATIONS IN ELECTROMAGNETICS NEURAL NETWORKS FOR THE CALCULATION OF BANDWIDTH OF RECTANGULAR MICROSTRIP... NEURAL NETWORKS FOR BANDWIDTH CALCULATION OF MICROSTRIP ANTENNAS 111 learning algorithms, conjugate gradient of Fletcher- Reeves (CGFR) [53], Levenberg

  14. Three-Axis Attitude Estimation With a High-Bandwidth Angular Rate Sensor

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Green, Joseph J.

    2013-01-01

    A continuing challenge for modern instrument pointing control systems is to meet the increasingly stringent pointing performance requirements imposed by emerging advanced scientific, defense, and civilian payloads. Instruments such as adaptive optics telescopes, space interferometers, and optical communications make unprecedented demands on precision pointing capabilities. A cost-effective method was developed for increasing the pointing performance for this class of NASA applications. The solution was to develop an attitude estimator that fuses star tracker and gyro measurements with a high-bandwidth angular rotation sensor (ARS). An ARS is a rate sensor whose bandwidth extends well beyond that of the gyro, typically up to 1,000 Hz or higher. The most promising ARS sensor technology is based on a magnetohydrodynamic concept, and has recently become available commercially. The key idea is that the sensor fusion of the star tracker, gyro, and ARS provides a high-bandwidth attitude estimate suitable for supporting pointing control with a fast-steering mirror or other type of tip/tilt correction for increased performance. The ARS is relatively inexpensive and can be bolted directly next to the gyro and star tracker on the spacecraft bus. The high-bandwidth attitude estimator fuses an ARS sensor with a standard three-axis suite comprised of a gyro and star tracker. The estimation architecture is based on a dual-complementary filter (DCF) structure. The DCF takes a frequency- weighted combination of the sensors such that each sensor is most heavily weighted in a frequency region where it has the lowest noise. An important property of the DCF is that it avoids the need to model disturbance torques in the filter mechanization. This is important because the disturbance torques are generally not known in applications. This property represents an advantage over the prior art because it overcomes a weakness of the Kalman filter that arises when fusing more than one rate

  15. A bandwidth efficient coding scheme for the Hubble Space Telescope

    NASA Technical Reports Server (NTRS)

    Pietrobon, Steven S.; Costello, Daniel J., Jr.

    1991-01-01

    As a demonstration of the performance capabilities of trellis codes using multidimensional signal sets, a Viterbi decoder was designed. The choice of code was based on two factors. The first factor was its application as a possible replacement for the coding scheme currently used on the Hubble Space Telescope (HST). The HST at present uses the rate 1/3 nu = 6 (with 2 (exp nu) = 64 states) convolutional code with Binary Phase Shift Keying (BPSK) modulation. With the modulator restricted to a 3 Msym/s, this implies a data rate of only 1 Mbit/s, since the bandwidth efficiency K = 1/3 bit/sym. This is a very bandwidth inefficient scheme, although the system has the advantage of simplicity and large coding gain. The basic requirement from NASA was for a scheme that has as large a K as possible. Since a satellite channel was being used, 8PSK modulation was selected. This allows a K of between 2 and 3 bit/sym. The next influencing factor was INTELSAT's intention of transmitting the SONET 155.52 Mbit/s standard data rate over the 72 MHz transponders on its satellites. This requires a bandwidth efficiency of around 2.5 bit/sym. A Reed-Solomon block code is used as an outer code to give very low bit error rates (BER). A 16 state rate 5/6, 2.5 bit/sym, 4D-8PSK trellis code was selected. This code has reasonable complexity and has a coding gain of 4.8 dB compared to uncoded 8PSK (2). This trellis code also has the advantage that it is 45 deg rotationally invariant. This means that the decoder needs only to synchronize to one of the two naturally mapped 8PSK signals in the signal set.

  16. Sent packing: protein engineering generates a new crystal form of Pseudomonas aeruginosa DsbA1 with increased catalytic surface accessibility

    SciTech Connect

    McMahon, Roisin M. Coinçon, Mathieu; Tay, Stephanie; Heras, Begoña; Morton, Craig J.; Scanlon, Martin J.; Martin, Jennifer L.

    2015-11-26

    The crystal structure of a P. aeruginosa DsbA1 variant is more suitable for fragment-based lead discovery efforts to identify inhibitors of this antimicrobial drug target. In the reported structures the active site of the protein can simultaneously bind multiple ligands introduced in the crystallization solution or via soaking. Pseudomonas aeruginosa is an opportunistic human pathogen for which new antimicrobial drug options are urgently sought. P. aeruginosa disulfide-bond protein A1 (PaDsbA1) plays a pivotal role in catalyzing the oxidative folding of multiple virulence proteins and as such holds great promise as a drug target. As part of a fragment-based lead discovery approach to PaDsbA1 inhibitor development, the identification of a crystal form of PaDsbA1 that was more suitable for fragment-soaking experiments was sought. A previously identified crystallization condition for this protein was unsuitable, as in this crystal form of PaDsbA1 the active-site surface loops are engaged in the crystal packing, occluding access to the target site. A single residue involved in crystal-packing interactions was substituted with an amino acid commonly found at this position in closely related enzymes, and this variant was successfully used to generate a new crystal form of PaDsbA1 in which the active-site surface is more accessible for soaking experiments. The PaDsbA1 variant displays identical redox character and in vitro activity to wild-type PaDsbA1 and is structurally highly similar. Two crystal structures of the PaDsbA1 variant were determined in complex with small molecules bound to the protein active site. These small molecules (MES, glycerol and ethylene glycol) were derived from the crystallization or cryoprotectant solutions and provide a proof of principle that the reported crystal form will be amenable to co-crystallization and soaking with small molecules designed to target the protein active-site surface.

  17. Low Bandwidth Vocoding using EM Sensor and Acoustic Signal Processing

    SciTech Connect

    Ng, L C; Holzrichter, J F; Larson, P E

    2001-10-25

    Low-power EM radar-like sensors have made it possible to measure properties of the human speech production system in real-time, without acoustic interference [1]. By combining these data with the corresponding acoustic signal, we've demonstrated an almost 10-fold bandwidth reduction in speech compression, compared to a standard 2.4 kbps LPC10 protocol used in the STU-III (Secure Terminal Unit, third generation) telephone. This paper describes a potential EM sensor/acoustic based vocoder implementation.

  18. Broadband metasurfaces enabling arbitrarily large delay-bandwidth products

    SciTech Connect

    Ginis, Vincent; Tassin, Philippe; Koschny, Thomas; Soukoulis, Costas M.

    2016-01-19

    Metasurfaces allow for advanced manipulation of optical signals by imposing phase discontinuities across flat interfaces. Unfortunately, these phase shifts remain restricted to values between 0 and 2π, limiting the delay-bandwidth product of such sheets. Here, we develop an analytical tool to design metasurfaces that mimic three-dimensional materials of arbitrary thickness. In this way, we demonstrate how large phase discontinuities can be realized by combining several subwavelength Lorentzian resonances in the unit cell of the surface. Finally, our methods open up the temporal response of metasurfaces and may lead to the construction of metasurfaces with a plethora of new optical functions.

  19. Systems for measuring response statistics of gigahertz bandwidth photomultipliers

    NASA Technical Reports Server (NTRS)

    Abshire, J. B.; Rowe, H. E.

    1977-01-01

    New systems have been developed for measuring the average impulse response, the pulse-height spectrum, the transit-time statistics as a function of signal level, and the dark-count spectrum of gigahertz bandwidth photomultipliers. Measurements showed that the 0.53 microns pulse used as an optical test source had a 30 picoseconds and less than 70 ps pulse width. Calibration data showed the system resolution to be less than 20 ps for root mean square transit-time measurements. Test data for a static crossed-field photomultiplier showed 2-photoelectron resolution and less than 30-ps time jitter over the 1- to 100-photoelectron range.

  20. Tunable polarization plasma channel undulator for narrow bandwidth photon emission

    NASA Astrophysics Data System (ADS)

    Rykovanov, S. G.; Wang, J. W.; Kharin, V. Yu.; Lei, B.; Schroeder, C. B.; Geddes, C. G. R.; Esarey, E.; Leemans, W. P.

    2016-09-01

    The theory of a plasma undulator excited by a short intense laser pulse in a parabolic plasma channel is presented. The undulator fields are generated either by the laser pulse incident off-axis and/or under the angle with respect to the channel axis. Linear plasma theory is used to derive the wakefield structure. It is shown that the electrons injected into the plasma wakefields experience betatron motion and undulator oscillations. Optimal electron beam injection conditions are derived for minimizing the amplitude of the betatron motion, producing narrow-bandwidth undulator radiation. Polarization control is readily achieved by varying the laser pulse injection conditions.

  1. Knowledge-based image bandwidth compression and enhancement

    NASA Astrophysics Data System (ADS)

    Saghri, John A.; Tescher, Andrew G.

    1987-01-01

    Techniques for incorporating a priori knowledge in the digital coding and bandwidth compression of image data are described and demonstrated. An algorithm for identifying and highlighting thin lines and point objects prior to coding is presented, and the precoding enhancement of a slightly smoothed version of the image is shown to be more effective than enhancement of the original image. Also considered are readjustment of the local distortion parameter and variable-block-size coding. The line-segment criteria employed in the classification are listed in a table, and sample images demonstrating the effectiveness of the enhancement techniques are presented.

  2. Holographically corrected telescope for high-bandwidth optical communications.

    PubMed

    Andersen, G; Knize, R J

    1999-11-20

    We present a design for an optical data communications receiver-transmitter pair based on the holographic correction of a large diameter, poor-quality, reflecting primary mirror. The telescope has a narrow bandwidth (<0.1 nm) with good signal frequency isolation (>60 dB) and is scalable to meter-class apertures. We demonstrate the correction of a reflector telescope with over 2000 waves of aberration to diffraction-limited operation, capable of handling data transmission rates up to 100 GHz.

  3. Large bandwidth op-amp based white noise current source

    NASA Astrophysics Data System (ADS)

    Giusi, Gino; Scandurra, Graziella; Ciofi, Carmine

    2014-02-01

    Electrical noise sources are basic building blocks in many measurement and instrumentation applications and in communication systems. In this paper, we propose a quite simple topology for the realization of a programmable, wide bandwidth, white noise current source that requires only two resistors and one operational amplifier. We validate the proposed approach by means of SPICE simulations and demonstrate, by means of proper measurements, the capability of generating a flat current noise spectrum in a frequency range up to four decades from a few Hz up to 100 kHz.

  4. Overcoming the detection bandwidth limit in precision spectroscopy: The analytical apparatus function for a stepped frequency scan

    NASA Astrophysics Data System (ADS)

    Rohart, François

    2017-01-01

    In a previous paper [Rohart et al., Phys Rev A 2014;90(042506)], the influence of detection-bandwidth properties on observed line-shapes in precision spectroscopy was theoretically modeled for the first time using the basic model of a continuous sweeping of the laser frequency. Specific experiments confirmed general theoretical trends but also revealed several insufficiencies of the model in case of stepped frequency scans. As a consequence in as much as up-to-date experiments use step-by-step frequency-swept lasers, a new model of the influence of the detection-bandwidth is developed, including a realistic timing of signal sampling and frequency changes. Using Fourier transform techniques, the resulting time domain apparatus function gets a simple analytical form that can be easily implemented in line-shape fitting codes without any significant increase of computation durations. This new model is then considered in details for detection systems characterized by 1st and 2nd order bandwidths, underlining the importance of the ratio of detection time constant to frequency step duration, namely for the measurement of line frequencies. It also allows a straightforward analysis of corresponding systematic deviations on retrieved line frequencies and broadenings. Finally, a special attention is paid to consequences of a finite detection-bandwidth in Doppler Broadening Thermometry, namely to experimental adjustments required for a spectroscopic determination of the Boltzmann constant at the 1-ppm level of accuracy. In this respect, the interest of implementing a Butterworth 2nd order filter is emphasized.

  5. Frequencies, bandwidths and magnitudes of vocal tract and surrounding tissue resonances, measured through the lips during phonation.

    PubMed

    Hanna, Noel; Smith, John; Wolfe, Joe

    2016-05-01

    The frequencies, magnitudes, and bandwidths of vocal tract resonances are all important in understanding and synthesizing speech. High precision acoustic impedance spectra of the vocal tracts of 10 subjects were measured from 10 Hz to 4.2 kHz by injecting a broadband acoustic signal through the lips. Between 300 Hz and 4 kHz the acoustic resonances R (impedance minima measured through the lips) and anti-resonances R¯ (impedance maxima) associated with the first three voice formants, have bandwidths of ∼50 to 90 Hz for men and ∼70 to 90 Hz for women. These acoustic resonances approximate those of a smooth, dry, rigid cylinder of similar dimensions, except that their bandwidths indicate higher losses in the vocal tract. The lossy, inertive load and airflow caused by opening the glottis further increase the bandwidths observed during phonation. The vocal tract walls are not rigid and measurements show an acousto-mechanical resonance R0 ∼ 20 Hz and anti-resonance R¯0∼200 Hz. These give an estimate of wall inertance consistent with an effective thickness of 1-2 cm and a wall stiffness of 2-4 kN m(-1). The non-rigidity of the tract imposes a lower limit of the frequency of the first acoustic resonance fR1 and the first formant F1.

  6. Increasing the impact of medical image computing using community-based open-access hackathons: The NA-MIC and 3D Slicer experience.

    PubMed

    Kapur, Tina; Pieper, Steve; Fedorov, Andriy; Fillion-Robin, J-C; Halle, Michael; O'Donnell, Lauren; Lasso, Andras; Ungi, Tamas; Pinter, Csaba; Finet, Julien; Pujol, Sonia; Jagadeesan, Jayender; Tokuda, Junichi; Norton, Isaiah; Estepar, Raul San Jose; Gering, David; Aerts, Hugo J W L; Jakab, Marianna; Hata, Nobuhiko; Ibanez, Luiz; Blezek, Daniel; Miller, Jim; Aylward, Stephen; Grimson, W Eric L; Fichtinger, Gabor; Wells, William M; Lorensen, William E; Schroeder, Will; Kikinis, Ron

    2016-10-01

    The National Alliance for Medical Image Computing (NA-MIC) was launched in 2004 with the goal of investigating and developing an open source software infrastructure for the extraction of information and knowledge from medical images using computational methods. Several leading research and engineering groups participated in this effort that was funded by the US National Institutes of Health through a variety of infrastructure grants. This effort transformed 3D Slicer from an internal, Boston-based, academic research software application into a professionally maintained, robust, open source platform with an international leadership and developer and user communities. Critical improvements to the widely used underlying open source libraries and tools-VTK, ITK, CMake, CDash, DCMTK-were an additional consequence of this effort. This project has contributed to close to a thousand peer-reviewed publications and a growing portfolio of US and international funded efforts expanding the use of these tools in new medical computing applications every year. In this editorial, we discuss what we believe are gaps in the way medical image computing is pursued today; how a well-executed research platform can enable discovery, innovation and reproducible science ("Open Science"); and how our quest to build such a software platform has evolved into a productive and rewarding social engineering exercise in building an open-access community with a shared vision.

  7. Designing and implementing Multibeam Smart Antennas for high bandwidth UAV communications using FPGAs

    NASA Astrophysics Data System (ADS)

    Porcello, J. C.

    Requirements for high bandwidth UAV communications are often necessary in order to move large amounts of mission information to/from Users in real-time. The focus of this paper is antenna beamforming for point-to-point, high bandwidth UAV communications in order to optimize transmit and receive power and support high data throughput communications. Specifically, this paper looks at the design and implementation of Multibeam Smart Antennas to implement antenna beamforming in an aerospace communications environment. The Smart Antenna is contrasted against Fast Fourier Transform (FFT) based beamforming in order to quantify the increase in both computational load and FPGA resources required for multibeam adaptive signal processing in the Smart Antenna. The paper begins with an overall discussion of Smart Antenna design and general beamforming issues in high bandwidth communications. Important design considerations such as processing complexity in a constrained Size, Weight and Power (SWaP) environment are discussed. The focus of the paper is with respect to design and implementation of digital beamforming wideband communications waveforms using FPGAs. A Multibeam Time Delay element is introduced based on Lagrange Interpolation. Design data for Multibeam Smart Antennas in FPGAs is provided in the paper as well as reference circuits for implementation. Finally, an example Multibeam Smart Antenna design is provided based on a Xilinx Virtex-7 FPGA. The Multibeam Smart Antenna example design illustrates the concepts discussed in the paper and provides design insight into Multibeam Smart Antenna implementation from the point of view of implementation complexity, required hardware, and overall system performance gain.

  8. Increasing Access to Mental Health Care With Breathe, an Internet-Based Program for Anxious Adolescents: Study Protocol for a Pilot Randomized Controlled Trial

    PubMed Central

    Wozney, Lori; Bagnell, Alexa; Fitzpatrick, Eleanor; Curtis, Sarah; Jabbour, Mona; Johnson, David; Rosychuk, Rhonda J; Young, Michael; Ohinmaa, Arto; Joyce, Anthony; McGrath, Patrick

    2016-01-01

    Background There is a demand to make first-line treatments, including cognitive behavioural therapy (CBT) for adolescent anxiety disorders, more widely available. Internet-based CBT is proposed to circumvent access and availability barriers and reduce health care system costs. Recent reviews suggest more evidence is needed to establish the treatment effects of Internet-based CBT in children and adolescents and to determine related economic impacts. Objective This pilot trial aims to collect the necessary data to inform the planning of a full-scale RCT to test the effectiveness of the Internet-based CBT program Breathe (Being Real, Easing Anxiety: Tools Helping Electronically). Methods We are conducting a 27-month, 2-arm parallel-group, pilot randomized controlled trial (RCT). Outcomes will inform the planning of a full-scale RCT aimed to test the effectiveness of Internet-based CBT with a population of adolescents with moderate to mild anxiety problems. In the pilot RCT we will: (1) define a minimal clinically important difference (MCID) for the primary outcome measure (total anxiety score using the Multidimensional Anxiety Scale for Children); (2) determine a sample size for the full-scale RCT; (3) estimate recruitment and retention rates; (4) measure intervention acceptability to inform critical intervention changes; (5) determine the use of co-interventions; and (6) conduct a cost-consequence analysis to inform a cost-effectiveness analysis in the full-scale RCT. Adolescents aged 13-17 years seeking care for an anxiety complaint from a participating emergency department, mobile or school-based crisis team, or primary care clinic are being screened for interest and eligibility. Enrolled adolescents are being randomly allocated to either 8 weeks of Internet-based CBT with limited telephone and e-mail support, or a control group with access to a static webpage listing anxiety resources. Adolescents are randomly assigned using a computer generated allocation

  9. Asymmetric MQW semiconductor optical amplifier with low-polarization sensitivity of over 90-nm bandwidth

    NASA Astrophysics Data System (ADS)

    Nkanta, Julie E.; Maldonado-Basilio, Ramón; Abdul-Majid, Sawsan; Zhang, Jessica; Hall, Trevor J.

    2013-12-01

    An exhausted capacity of current Passive Optical Networks has been anticipated as bandwidth-hungry applications such as HDTV and 3D video become available to end-users. To enhance their performance, the next generation optical access networks have been proposed, using optical carriers allocated within the E-band (1360-1460 nm). It is partly motivated by the low-water peak fiber being manufactured by Corning. At these wavelengths, choices for low cost optical amplifiers, with compact size, low energy consumption and feasibility for integration with other optoelectronic components are limited, making the semiconductor optical amplifiers (SOA) a realistic solution. An experimental characterization of a broadband and low polarization sensitive asymmetric multi quantum well (MQW) SOA operating in the E-band is reported. The SOA device is composed of nine 6 nm In1-xGaxAsyP1-y 0.2% tensile strained asymmetric MQW layers sandwiched between nine latticed matched 6 nm InGaAsP barrier layers. The active region is grown on an n-doped InP substrate and buried by p-doped InGaAsP layers. The SOA devices have 7-degrees tilt anti-reflected coated facets, with 2 μm ridge width, and a cavity length of 900 μm. For input powers of -10 dBm and -20 dBm, a maximum gain of 20 dB at 1360 nm with a polarization insensitivity under 3 dB for over 90 nm bandwidth is measured. Polarization sensitivity of less than 0.5 dB is observed for some wavelengths. Obtained results indicate a promising SOA with broadband amplification, polarization insensitivity and high gain. These SOAs were designed and characterized at the Photonics Technology Laboratory, University of Ottawa, Canada.

  10. Influence of masker bandwidth on binaural masking level differences.

    PubMed

    Harris, R W; Brey, R H; Miller, R W; Channell, R W

    1992-01-01

    Masking level differences (MLDs) were investigated using masking noise with 160 Hz (amplitude-modulated noise) and 600 Hz (filtered-random noise) bandwidth. One hundred normally hearing subjects received the MLD test under both types of noise. Significant differences between noise types were observed in both N0S pi and N pi S0 conditions; MLDs were larger in amplitude-modulated noise. Consideration of these differences would indicate that older MLD norms based solely on filtered-random noise are invalid for amplitude-modulated noise especially where bandwidth differences in the noise exist. Were the norms for 600-Hz-wide filtered-random noise to be applied to results of MLD testing performed using 160-Hz-wide amplitude-modulated noise, patients with lesions in the central auditory pathway might exhibit normal or borderline normal results. Clinical MLD norms established on one type of noise should not be used to interpret MLD results obtained using a different type of noise.

  11. Series-fed circularly polarized microstrip antennas with broad bandwidth

    NASA Astrophysics Data System (ADS)

    Mao, Shau-Gang; Chen, Shiou-Li; Yeh, Jen-Chun; Lin, Tien-Min

    2007-08-01

    A new series-fed circularly polarized antenna (SFCPA) in microstrip configuration, which consists of a traveling-wave-type crank-line antenna (CLA) and a resonant-type square-ring slot antenna (SRSA), is developed. Unlike the conventional crank-line (CL) antenna array with an open end or a resistive load, the proposed SFCPA uses the SRSA at the termination of the CLA and thus exhibits not only a broad circularly polarized (CP) bandwidth but also a large antenna gain. The characteristics of the SFCPA, including the leaky-wave radiation and the circular polarization, are examined in terms of the dispersion diagram and the current distribution. The SFCPA with the two-cell CLA and the terminated SRSA is fabricated and measured to demonstrate the 10-dB return loss and 3-dB axial ratio (AR) bandwidths of 34.3% and 30.5%, respectively. The frequency-scanning radiation patterns with a 5-7 dBi antenna gain are also presented in the operating band.

  12. Specification for wide channel bandwidth one-inch video tape

    NASA Technical Reports Server (NTRS)

    Perry, Jimmy L.

    1988-01-01

    Standards and controls are established for the procurement of wide channel bandwidth one inch video magnetic recording tapes for Very Long Base Interferometer (VLBI) system applications. The Magnetic Tape Certification Facility (MTCF) currently maintains three specifications for the Quality Products List (QPL) and acceptance testing of magnetic tapes. NASA-TM-79724 is used for the QPL and acceptance testing of new analog tapes; NASA-TM-80599 is used for QPL and acceptance testing of new digital tapes; and NASA-TM-100702 is used for the QPL and acceptance testing of new IBM/IBM compatible 3480 magnetic tape cartridges. This specification will be used for the QPL and acceptance testing of new wide channel bandwidth one inch video magnetic recording tapes. The one inch video tapes used by the Jet Propulsion Lab., the Deep Space Network and the Haystack Observatory will be covered by this specification. These NASA stations will use the video tapes for their VLBI system applications. The VLBI system is used for the tracking of quasars and the support of interplanetary exploration.

  13. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, K. P.

    1986-01-01

    Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.

  14. A wide bandwidth electrostatic field sensor for lightning research

    NASA Technical Reports Server (NTRS)

    Zaepfel, Klaus P.

    1989-01-01

    Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.

  15. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    NASA Astrophysics Data System (ADS)

    Chen, Ke; Yang, Zhongjie; Feng, Yijun; Zhu, Bo; Zhao, Junming; Jiang, Tian

    2015-06-01

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens' surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  16. Multi-Modulator for Bandwidth-Efficient Communication

    NASA Technical Reports Server (NTRS)

    Gray, Andrew; Lee, Dennis; Lay, Norman; Cheetham, Craig; Fong, Wai; Yeh, Pen-Shu; King, Robin; Ghuman, Parminder; Hoy, Scott; Fisher, Dave

    2009-01-01

    A modulator circuit board has recently been developed to be used in conjunction with a vector modulator to generate any of a large number of modulations for bandwidth-efficient radio transmission of digital data signals at rates than can exceed 100 Mb/s. The modulations include quadrature phaseshift keying (QPSK), offset quadrature phase-shift keying (OQPSK), Gaussian minimum-shift keying (GMSK), and octonary phase-shift keying (8PSK) with square-root raised-cosine pulse shaping. The figure is a greatly simplified block diagram showing the relationship between the modulator board and the rest of the transmitter. The role of the modulator board is to encode the incoming data stream and to shape the resulting pulses, which are fed as inputs to the vector modulator. The combination of encoding and pulse shaping in a given application is chosen to maximize the bandwidth efficiency. The modulator board includes gallium arsenide serial-to-parallel converters at its input end. A complementary metal oxide/semiconductor (CMOS) field-programmable gate array (FPGA) performs the coding and modulation computations and utilizes parallel processing in doing so. The results of the parallel computation are combined and converted to pulse waveforms by use of gallium arsenide parallel-to-serial converters integrated with digital-to-analog converters. Without changing the hardware, one can configure the modulator to produce any of the designed combinations of coding and modulation by loading the appropriate bit configuration file into the FPGA.

  17. Programmable noise bandwidth reduction by means of digital averaging

    NASA Technical Reports Server (NTRS)

    Poklemba, John J. (Inventor)

    1993-01-01

    Predetection noise bandwidth reduction is effected by a pre-averager capable of digitally averaging the samples of an input data signal over two or more symbols, the averaging interval being defined by the input sampling rate divided by the output sampling rate. As the averaged sample is clocked to a suitable detector at a much slower rate than the input signal sampling rate the noise bandwidth at the input to the detector is reduced, the input to the detector having an improved signal to noise ratio as a result of the averaging process, and the rate at which such subsequent processing must operate is correspondingly reduced. The pre-averager forms a data filter having an output sampling rate of one sample per symbol of received data. More specifically, selected ones of a plurality of samples accumulated over two or more symbol intervals are output in response to clock signals at a rate of one sample per symbol interval. The pre-averager includes circuitry for weighting digitized signal samples using stored finite impulse response (FIR) filter coefficients. A method according to the present invention is also disclosed.

  18. Unmanned Aircraft System Control and ATC Communications Bandwidth Requirements

    NASA Technical Reports Server (NTRS)

    Henriksen, Steve

    2008-01-01

    There are significant activities taking place to establish the procedures and requirements for safe and routine operation of unmanned aircraft systems (UAS) in the National Airspace System (NAS). Among the barriers to overcome in achieving this goal is the lack of sufficient frequency spectrum necessary for the UAS control and air traffic control (ATC) communications links. This shortcoming is compounded by the fact that the UAS control communications links will likely be required to operate in protected frequency spectrum, just as ATC communications links are, because they relate to "safety and regularity of flight." To support future International Telecommunications Union (ITU) World Radio Conference (WRC) agenda items concerning new frequency allocations for UAS communications links, and to augment the Future Communications Study (FCS) Technology Evaluation Group efforts, NASA Glenn Research Center has sponsored a task to estimate the UAS control and ATC communications bandwidth requirements for safe, reliable, and routine operation of UAS in the NAS. This report describes the process and results of that task. The study focused on long-term bandwidth requirements for UAS approximately through 2030.

  19. Improving microwave antenna gain and bandwidth with phase compensation metasurface

    SciTech Connect

    Chen, Ke; Yang, Zhongjie; Feng, Yijun Zhu, Bo; Zhao, Junming; Jiang, Tian

    2015-06-15

    Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens’ surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.

  20. The Effect of Pulse Shaping QPSK on Bandwidth Efficiency

    NASA Technical Reports Server (NTRS)

    Purba, Josua Bisuk Mubyarto; Horan, Shelia

    1997-01-01

    This research investigates the effect of pulse shaping QPSK on bandwidth efficiency over a non-linear channel. This investigation will include software simulations and the hardware implementation. Three kinds of filters: the 5th order Butterworth filter, the 3rd order Bessel filter and the Square Root Raised Cosine filter with a roll off factor (alpha) of 0.25,0.5 and 1, have been investigated as pulse shaping filters. Two different high power amplifiers, one a Traveling Wave Tube Amplifier (TWTA) and the other a Solid State Power Amplifier (SSPA) have been investigated in the hardware implementation. A significant improvement in the bandwidth utilization (rho) for the filtered data compared to unfiltered data through the non-linear channel is shown in the results. This method promises strong performance gains in a bandlimited channel when compared to unfiltered systems. This work was conducted at NMSU in the Center for Space Telemetering, and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department and is supported by a grant from the National Aeronautics and Space Administration (NASA) NAG5-1491.

  1. Web Accessibility and Accessibility Instruction

    ERIC Educational Resources Information Center

    Green, Ravonne A.; Huprich, Julia

    2009-01-01

    Section 508 of the Americans with Disabilities Act (ADA) mandates that programs and services be accessible to people with disabilities. While schools of library and information science (SLIS*) and university libraries should model accessible Web sites, this may not be the case. This article examines previous studies about the Web accessibility of…

  2. Printed wide-slot antenna design with bandwidth and gain enhancement on low-cost substrate.

    PubMed

    Samsuzzaman, M; Islam, M T; Mandeep, J S; Misran, N

    2014-01-01

    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS.

  3. Printed Wide-Slot Antenna Design with Bandwidth and Gain Enhancement on Low-Cost Substrate

    PubMed Central

    Samsuzzaman, M.; Islam, M. T.; Mandeep, J. S.; Misran, N.

    2014-01-01

    This paper presents a printed wide-slot antenna design and prototyping on available low-cost polymer resin composite material fed by a microstrip line with a rotated square slot for bandwidth enhancement and defected ground structure for gain enhancement. An I-shaped microstrip line is used to excite the square slot. The rotated square slot is embedded in the middle of the ground plane, and its diagonal points are implanted in the middle of the strip line and ground plane. To increase the gain, four L-shaped slots are etched in the ground plane. The measured results show that the proposed structure retains a wide impedance bandwidth of 88.07%, which is 20% better than the reference antenna. The average gain is also increased, which is about 4.17 dBi with a stable radiation pattern in the entire operating band. Moreover, radiation efficiency, input impedance, current distribution, axial ratio, and parametric studies of S11 for different design parameters are also investigated using the finite element method-based simulation software HFSS. PMID:24696661

  4. Wide bandwidth instantaneous radio frequency spectrum analyzer based on nitrogen vacancy centers in diamond

    NASA Astrophysics Data System (ADS)

    Chipaux, M.; Toraille, L.; Larat, C.; Morvan, L.; Pezzagna, S.; Meijer, J.; Debuisschert, T.

    2015-12-01

    We propose an original analog method to perform instantaneous and quantitative spectral analysis of microwave signals. An ensemble of nitrogen-vacancy (NV) centers held in a diamond plate is pumped by a 532 nm laser. Its photoluminescence is imaged through an optical microscope and monitored by a digital camera. An incoming microwave signal is converted into a microwave field in the area of the NV centers by a loop shaped antenna. The resonances induced by the magnetic component of that field are detected through a decrease of the NV centers photoluminescence. A magnetic field gradient induces a Zeeman shift of the resonances and transforms the frequency information into spatial information, which allows for the simultaneous analysis of the microwave signal in the entire frequency bandwidth of the device. The time dependent spectral analysis of an amplitude modulated microwave signal is demonstrated over a bandwidth of 600 MHz , associated to a frequency resolution of 7 MHz , and a refresh rate of 4 ms . With such integration time, a field of a few hundreds of μ W can be detected. Since the optical properties of NV centers can be maintained even in high magnetic field, we estimate that an optimized device could allow frequency analysis in a range of 30 GHz , only limited by the amplitude of the magnetic field gradient. In addition, an increase of the NV centers quantity could lead both to an increase of the microwave sensitivity and to a decrease of the minimum refresh rate down to a few μ s .

  5. Interaural time processing when stimulus bandwidth differs at the two ears.

    PubMed

    Brown, Christopher A; Yost, William A

    2013-01-01

    Advances in the design of cochlear implants (CIs), as well as improved CI surgical techniques, have led to an increase in the number of patients who retain some residual low-frequency acoustic hearing in the implanted ear. Many of these patients also possess some hearing in the unimplanted ear. Although their low-frequency audiometric configurations will likely be asymmetrical across ears, they may nevertheless be able to process interaural time differences (ITDs) which might aid them in localizing sound sources and achieving a spatial release from masking. We recently published research (Brown and Yost 2011) showing how sensitivity to ITD differences was affected when the stimulus bandwidths were varied between the ears, to simulate asymmetrical hearing loss in the low-frequency region. We showed that ITD discrimination thresholds decreased as the bandwidth of the noise presented to one ear increased beyond that presented to the other ear. In the current experiment, we expand upon those conditions to ­further explore ITD processing in the presence of interaural spectral differences. ITD sensitivity was measured when a fixed band of noise was presented to one ear and the center frequency of a spectral band of the same width was moved upward in frequency in the other ear. The data suggest that listeners have difficulty attending to ITD differences in one spectral region when there are other spectral regions that contain conflicting or inconsistent spatial information, which is likely to be the case for many CI patients who possess bilateral residual hearing.

  6. Nonlinear frequency compression: Influence of start frequency and input bandwidth on consonant and vowel recognitiona)

    PubMed Central

    Alexander, Joshua M.

    2016-01-01

    By varying parameters that control nonlinear frequency compression (NFC), this study examined how different ways of compressing inaudible mid- and/or high-frequency information at lower frequencies influences perception of consonants and vowels. Twenty-eight listeners with mild to moderately severe hearing loss identified consonants and vowels from nonsense syllables in noise following amplification via a hearing aid simulator. Low-pass filtering and the selection of NFC parameters fixed the output bandwidth at a frequency representing a moderately severe (3.3 kHz, group MS) or a mild-to-moderate (5.0 kHz, group MM) high-frequency loss. For each group (n = 14), effects of six combinations of NFC start frequency (SF) and input bandwidth [by varying the compression ratio (CR)] were examined. For both groups, the 1.6 kHz SF significantly reduced vowel and consonant recognition, especially as CR increased; whereas, recognition was generally unaffected if SF increased at the expense of a higher CR. Vowel recognition detriments for group MS were moderately correlated with the size of the second formant frequency shift following NFC. For both groups, significant improvement (33%–50%) with NFC was confined to final /s/ and /z/ and to some VCV tokens, perhaps because of listeners' limited exposure to each setting. No set of parameters simultaneously maximized recognition across all tokens. PMID:26936574

  7. Leaf water storage increases with salinity and aridity in the mangrove Avicennia marina: integration of leaf structure, osmotic adjustment, and access to multiple water sources.

    PubMed

    Nguyen, Hoa T; Meir, Patrick; Sack, Lawren; Evans, John R; Oliveira, Rafael S; Ball, Marilyn C

    2017-04-05

    Leaf structure and water relations were studied in a temperate population of Avicennia marina subsp. australasica along a natural salinity gradient (28 to 49 parts per thousand (ppt)) and compared with two subspecies grown naturally in similar soil salinities to those of subsp. australasica but under different climates: subsp. eucalyptifolia (salinity 30 ppt, wet tropics) and subsp. marina (salinity 46 ppt, arid tropics). Leaf thickness, leaf dry mass per area, and water content increased with salinity and aridity. Turgor loss point declined with increase in soil salinity, driven mainly by differences in osmotic potential at full turgor. Nevertheless, a high modulus of elasticity (ε) contributed to maintenance of high cell hydration at turgor loss point. Despite similarity among leaves in leaf water storage capacitance, total leaf water storage increased with increasing salinity and aridity. The time that stored water alone could sustain an evaporation rate of 1 mmol m(-2) s(-1) ranged from 77 to 126 min from subspecies eucalyptifolia to ssp. marina, respectively. Achieving full leaf hydration or turgor would require water from sources other than the roots, emphasizing the importance of multiple water sources to growth and survival of Avicennia marina across gradients in salinity and aridity.

  8. Expanding Access and Increasing Success in Postsecondary Education for Arizonans. The Arizona Commission for Postsecondary Education (ACPE) 2009-2010 Annual Report

    ERIC Educational Resources Information Center

    Arizona Commission for Postsecondary Education, 2010

    2010-01-01

    The work of the Arizona Commission for Postsecondary Education (ACPE) is guided by a strategic plan. The purpose of the plan is to provide focus for the activity of this small agency and its five staff members in order to increase productivity and impact in the areas of its statutory authority. The mission and goals were accepted by Commissioners…

  9. Expanding Access and Increasing Success in Postsecondary Education for Arizonans. The Arizona Commission for Postsecondary Education (ACPE) 2006-2007 Annual Report

    ERIC Educational Resources Information Center

    Arizona Commission for Postsecondary Education, 2007

    2007-01-01

    The work of the Arizona Commission for Postsecondary Education (ACPE) is guided by a 5 year strategic plan. The purpose of the plan is to provide focus for the activity of this small agency and its eight staff members in order to increase productivity and impact in the areas of its statutory authority. The mission and goals were accepted by…

  10. Expanding Access and Increasing Success in Postsecondary Education for Arizonans. The Arizona Commission for Postsecondary Education (ACPE) 2007-2008 Annual Report

    ERIC Educational Resources Information Center

    Arizona Commission for Postsecondary Education, 2008

    2008-01-01

    The work of the Arizona Commission for Postsecondary Education (ACPE) is guided by a 5-year strategic plan. The purpose of the plan is to provide focus for the activity of this small agency and its nine staff members in order to increase productivity and impact in the areas of its statutory authority. The mission and goals were accepted by …

  11. Expanding Access and Increasing Success in Postsecondary Education for Arizonans. The Arizona Commission for Postsecondary Education (ACPE) 2008-2009 Annual Report

    ERIC Educational Resources Information Center

    Arizona Commission for Postsecondary Education, 2009

    2009-01-01

    The work of the Arizona Commission for Postsecondary Education (ACPE) is guided by a 5-year strategic plan. The purpose of the plan is to provide focus for the activity of this small agency and its eight staff members in order to increase productivity and impact in the areas of its statutory authority. The mission and goals were accepted by…

  12. Auditory masking in three pinnipeds: Aerial critical ratios and direct critical bandwidth measurements

    NASA Astrophysics Data System (ADS)

    Southall, Brandon L.; Schusterman, Ronald J.; Kastak, David

    2003-09-01

    This study expands the limited understanding of pinniped aerial auditory masking and includes measurements at some of the relatively low frequencies predominant in many pinniped vocalizations. Behavioral techniques were used to obtain aerial critical ratios (CRs) within a hemianechoic chamber for a northern elephant seal (Mirounga angustirostris), a harbor seal (Phoca vitulina), and a California sea lion (Zalophus californianus). Simultaneous, octave-band noise maskers centered at seven test frequencies (0.2-8.0 kHz) were used to determine aerial CRs. Narrower and variable bandwidth masking noise was also used in order to obtain direct critical bandwidths (CBWs). The aerial CRs are very similar in magnitude and in frequency-specific differences (increasing gradually with test frequency) to underwater CRs for these subjects, demonstrating that pinniped cochlear processes are similar both in air and water. While, like most mammals, these pinniped subjects apparently lack specialization for enhanced detection of specific frequencies over masking noise, they consistently detect signals across a wide range of frequencies at relatively low signal-to-noise ratios. Direct CBWs are 3.2 to 14.2 times wider than estimated based on aerial CRs. The combined masking data are significant in terms of assessing aerial anthropogenic noise impacts, effective aerial communicative ranges, and amphibious aspects of pinniped cochlear mechanics.

  13. Graphene electro-optic modulator with 30 GHz bandwidth

    NASA Astrophysics Data System (ADS)

    Phare, Christopher T.; Daniel Lee, Yoon-Ho; Cardenas, Jaime; Lipson, Michal

    2015-08-01

    Graphene has generated exceptional interest as an optoelectronic material because its high carrier mobility and broadband absorption promise to make extremely fast and broadband electro-optic devices possible. Electro-optic graphene modulators previously reported, however, have been limited in bandwidth to a few gigahertz because of the large capacitance required to achieve reasonable voltage swings. Here, we demonstrate a graphene electro-optic modulator based on resonator loss modulation at critical coupling that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth and with a state-of-the-art modulation efficiency of 15 dB per 10 V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and nonlinear optics.

  14. A new low voltage level-shifted FVF current mirror with enhanced bandwidth and output resistance

    NASA Astrophysics Data System (ADS)

    Aggarwal, Bhawna; Gupta, Maneesha; Gupta, Anil Kumar; Sangal, Ankur

    2016-10-01

    This paper proposes a new high-performance level-shifted flipped voltage follower (LSFVF) based low-voltage current mirror (CM). The proposed CM utilises the low-supply voltage and low-input resistance characteristics of a flipped voltage follower (FVF) CM. In the proposed CM, level-shifting configuration is used to obtain a wide operating current range and resistive compensation technique is employed to increase the operating bandwidth. The peaking in frequency response is reduced by using an additional large MOSFET. Moreover, a very high output resistance (in GΩ range) along with low-current transfer error is achieved through super-cascode configuration for a wide current range (0-440 µA). Small signal analysis is carried out to show the improvements achieved at each step. The proposed CM is simulated by Mentor Graphics Eldospice in TSMC 0.18 µm CMOS, BSIM3 and Level 53 technology. In the proposed CM, a bandwidth of 6.1799 GHz, 1% settling time of 0.719 ns, input and output resistances of 21.43 Ω and 1.14 GΩ, respectively, are obtained with a single supply voltage of 1 V. The layout of the proposed CM has been designed and post-layout simulation results have been shown. The post-layout simulation results for Monte Carlo and temperature analysis have also been included to show the reliability of the CM against the variations in process parameters and temperature changes.

  15. Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, M. A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n = 3.4, low loss, and relatively high thermal conductivity is a nearly optimal material for these purposes, but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coffecient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated and coated silicon lenses as large as 33.4 cm in diameter with coatings optimized for use between 125-165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30 deg. with low cross-polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to sub-millimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  16. Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, Manuel A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n 3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating.We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30deg with low cross polarization.We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  17. Extending MIL-STD-1553 bandwidth: a study of impairments, EMI, and channel capacity

    NASA Astrophysics Data System (ADS)

    Hegarty, Michael G.

    2004-09-01

    This paper explores the possibility of increasing the data rates on existing MIL-STD-1553 networks beyond its current one megabit per second rate. A combination of empirical and theoretical methods is used in predicting the capacity of a MIL-STD-1553 network. The analysis begins with an assessment of the usable bandwidth in a 1553 network followed by the development of models to predict signal-to-noise ratios based on a transmit signal level that meets the emissions limits of MIL-STD-461 and a noise level that is representative of a real 1553 system. This paper presents the theoretical capacity limits for several 1553 network configurations. The results of the analysis predict that the theoretical capacity within a legacy MIL-STD-1553 system is expected to be several hundred megabits per second. The achievable rate depends on network configuration and usable bandwidth. Methods of approaching these theoretical capacity limits is not discussed in this paper, rather, this paper provides a framework and a baseline for the analysis of higher data rates over legacy MIL-STD-1553 networks.

  18. Near-ideal optical metamaterial absorbers with super-octave bandwidth.

    PubMed

    Bossard, Jeremy A; Lin, Lan; Yun, Seokho; Liu, Liu; Werner, Douglas H; Mayer, Theresa S

    2014-02-25

    Nanostructured optical coatings with tailored spectral absorption properties are of interest for a wide range of applications such as spectroscopy, emissivity control, and solar energy harvesting. Optical metamaterial absorbers have been demonstrated with a variety of customized single band, multiple band, polarization, and angular configurations. However, metamaterials that provide near unity absorptivity with super-octave bandwidth over a specified optical wavelength range have not yet been demonstrated experimentally. Here, we show a broadband, polarization-insensitive metamaterial with greater than 98% measured average absorptivity that is maintained over a wide ± 45° field-of-view for mid-infrared wavelengths between 1.77 and 4.81 μm. The nearly ideal absorption is realized by using a genetic algorithm to identify the geometry of a single-layer metal nanostructure array that excites multiple overlapping electric resonances with high optical loss across greater than an octave bandwidth. The response is optimized by substituting palladium for gold to increase the infrared metallic loss and by introducing a dielectric superstrate to suppress reflection over the entire band. This demonstration advances the state-of-the-art in high-performance broadband metamaterial absorbers that can be reliably fabricated using a single patterned layer of metal nanostructures.

  19. Development of high frequency and wide bandwidth Johnson noise thermometry

    SciTech Connect

    Crossno, Jesse; Liu, Xiaomeng; Kim, Philip; Ohki, Thomas A.; Fong, Kin Chung

    2015-01-12

    We develop a high frequency, wide bandwidth radiometer operating at room temperature, which augments the traditional technique of Johnson noise thermometry for nanoscale thermal transport studies. Employing low noise amplifiers and an analog multiplier operating at 2 GHz, auto- and cross-correlated Johnson noise measurements are performed in the temperature range of 3 to 300 K, achieving a sensitivity of 5.5 mK (110 ppm) in 1 s of integration time. This setup allows us to measure the thermal conductance of a boron nitride encapsulated monolayer graphene device over a wide temperature range. Our data show a high power law (T ∼ 4) deviation from the Wiedemann-Franz law above T ∼ 100 K.

  20. Description of a New 400 MHZ Bandwidth Chirp Transform Spectrometer

    NASA Astrophysics Data System (ADS)

    Paganini, Lucas; Hartogh, Paul

    A new chirp transform spectrometer (CTS) with a bandwidth of 400 MHz and a spectral resolution of 100 kHz has been developed. The CTS is deviced using a digital chirp generator and a preprocessing unit based on a Complementary Metal Oxide Semiconductor (CMOS) and an Application-Specific Integrated Circuit (ASIC). A build in PC 104 computer handles the process control and the external communication via Ethernet and a Transistor-Transistor Logic (TTL) interface. The CTS has been applied to atmospheric science, i.e., a 25-K noise temperature, 22-GHz water vapor, and a 142-GHz ozone system. Astronomical observations have been performed using the Heinrich Hertz submillimeter telescope. In this paper, we describe the function of the CTS and provide information about its functional performance.