WorldWideScience

Sample records for partially blind multiuser

  1. AudioMUD: a multiuser virtual environment for blind people.

    Science.gov (United States)

    Sánchez, Jaime; Hassler, Tiago

    2007-03-01

    A number of virtual environments have been developed during the last years. Among them there are some applications for blind people based on different type of audio, from simple sounds to 3-D audio. In this study, we pursued a different approach. We designed AudioMUD by using spoken text to describe the environment, navigation, and interaction. We have also introduced some collaborative features into the interaction between blind users. The core of a multiuser MUD game is a networked textual virtual environment. We developed AudioMUD by adding some collaborative features to the basic idea of a MUD and placed a simulated virtual environment inside the human body. This paper presents the design and usability evaluation of AudioMUD. Blind learners were motivated when interacted with AudioMUD and helped to improve the interaction through audio and interface design elements.

  2. Adaptive DSP Algorithms for UMTS: Blind Adaptive MMSE and PIC Multiuser Detection

    NARCIS (Netherlands)

    Potman, J.

    2003-01-01

    A study of the application of blind adaptive Minimum Mean Square Error (MMSE) and Parallel Interference Cancellation (PIC) multiuser detection techniques to Wideband Code Division Multiple Access (WCDMA), the physical layer of Universal Mobile Telecommunication System (UMTS), has been performed as

  3. Blind Multiuser Detection by Kurtosis Maximization for Asynchronous Multirate DS/CDMA Systems

    Directory of Open Access Journals (Sweden)

    Peng Chun-Hsien

    2006-01-01

    Full Text Available Chi et al. proposed a fast kurtosis maximization algorithm (FKMA for blind equalization/deconvolution of multiple-input multiple-output (MIMO linear time-invariant systems. This algorithm has been applied to blind multiuser detection of single-rate direct-sequence/code-division multiple-access (DS/CDMA systems and blind source separation (or independent component analysis. In this paper, the FKMA is further applied to blind multiuser detection for multirate DS/CDMA systems. The ideas are to properly formulate discrete-time MIMO signal models by converting real multirate users into single-rate virtual users, followed by the use of FKMA for extraction of virtual users' data sequences associated with the desired user, and recovery of the data sequence of the desired user from estimated virtual users' data sequences. Assuming that all the users' spreading sequences are given a priori, two multirate blind multiuser detection algorithms (with either a single receive antenna or multiple antennas, which also enjoy the merits of superexponential convergence rate and guaranteed convergence of the FKMA, are proposed in the paper, one based on a convolutional MIMO signal model and the other based on an instantaneous MIMO signal model. Some simulation results are then presented to demonstrate their effectiveness and to provide a performance comparison with some existing algorithms.

  4. Full-diversity partial interference cancellation for multi-user wireless relaying networks

    KAUST Repository

    El Astal, M. T O

    2013-12-01

    We focus on the uplink channel of multi-user wireless relaying networks in a coverage extension scenario. The network consists of two users, a single half duplex (HD) relay and a destination, all equipped with multiple antennas. Perfect channel state information (CSI) is assumed to be available exclusively at the receiving nodes (i.e., the relay and the destination) while the users are assumed to be completely blind. The communication through the considered network takes place over two phases. During the first phase, both users send their information concurrently to the relay. The second phase consists of decoding the received data and forwarding it simultaneously to the destination. A transmission scheme that achieves full-diversity under partial interference cancellation (PIC) group decoding is proposed. Unlike many existing schemes, it allows the concurrent transmission in both phases while achieving the full-diversity gain of full time division multiple access (TDMA) transmission regardless of the number of antennas at each node. Numerical comparison with existing schemes in the literature is provided to corroborate our theoretical claims. It is found that our interference cancellation (IC) scheme clearly outperforms existing schemes at the expense of an affordable increase in decoding complexity at both of the relay and destination. © 2013 IEEE.

  5. Full-diversity partial interference cancellation for multi-user wireless relaying networks

    KAUST Repository

    El Astal, M. T O; Ismail, Amr; Alouini, Mohamed-Slim; Olivier, Jan Corné

    2013-01-01

    We focus on the uplink channel of multi-user wireless relaying networks in a coverage extension scenario. The network consists of two users, a single half duplex (HD) relay and a destination, all equipped with multiple antennas. Perfect channel state information (CSI) is assumed to be available exclusively at the receiving nodes (i.e., the relay and the destination) while the users are assumed to be completely blind. The communication through the considered network takes place over two phases. During the first phase, both users send their information concurrently to the relay. The second phase consists of decoding the received data and forwarding it simultaneously to the destination. A transmission scheme that achieves full-diversity under partial interference cancellation (PIC) group decoding is proposed. Unlike many existing schemes, it allows the concurrent transmission in both phases while achieving the full-diversity gain of full time division multiple access (TDMA) transmission regardless of the number of antennas at each node. Numerical comparison with existing schemes in the literature is provided to corroborate our theoretical claims. It is found that our interference cancellation (IC) scheme clearly outperforms existing schemes at the expense of an affordable increase in decoding complexity at both of the relay and destination. © 2013 IEEE.

  6. A MUSIC-Based Algorithm for Blind User Identification in Multiuser DS-CDMA

    Directory of Open Access Journals (Sweden)

    M. Reza Soleymani

    2005-04-01

    Full Text Available A blind scheme based on multiple-signal classification (MUSIC algorithm for user identification in a synchronous multiuser code-division multiple-access (CDMA system is suggested. The scheme is blind in the sense that it does not require prior knowledge of the spreading codes. Spreading codes and users' power are acquired by the scheme. Eigenvalue decomposition (EVD is performed on the received signal, and then all the valid possible signature sequences are projected onto the subspaces. However, as a result of this process, some false solutions are also produced and the ambiguity seems unresolvable. Our approach is to apply a transformation derived from the results of the subspace decomposition on the received signal and then to inspect their statistics. It is shown that the second-order statistics of the transformed signal provides a reliable means for removing the false solutions.

  7. Blind information-theoretic multiuser detection algorithms for DS-CDMA and WCDMA downlink systems.

    Science.gov (United States)

    Waheed, Khuram; Salem, Fathi M

    2005-07-01

    Code division multiple access (CDMA) is based on the spread-spectrum technology and is a dominant air interface for 2.5G, 3G, and future wireless networks. For the CDMA downlink, the transmitted CDMA signals from the base station (BS) propagate through a noisy multipath fading communication channel before arriving at the receiver of the user equipment/mobile station (UE/MS). Classical CDMA single-user detection (SUD) algorithms implemented in the UE/MS receiver do not provide the required performance for modern high data-rate applications. In contrast, multi-user detection (MUD) approaches require a lot of a priori information not available to the UE/MS. In this paper, three promising adaptive Riemannian contra-variant (or natural) gradient based user detection approaches, capable of handling the highly dynamic wireless environments, are proposed. The first approach, blind multiuser detection (BMUD), is the process of simultaneously estimating multiple symbol sequences associated with all the users in the downlink of a CDMA communication system using only the received wireless data and without any knowledge of the user spreading codes. This approach is applicable to CDMA systems with relatively short spreading codes but becomes impractical for systems using long spreading codes. We also propose two other adaptive approaches, namely, RAKE -blind source recovery (RAKE-BSR) and RAKE-principal component analysis (RAKE-PCA) that fuse an adaptive stage into a standard RAKE receiver. This adaptation results in robust user detection algorithms with performance exceeding the linear minimum mean squared error (LMMSE) detectors for both Direct Sequence CDMA (DS-CDMA) and wide-band CDMA (WCDMA) systems under conditions of congestion, imprecise channel estimation and unmodeled multiple access interference (MAI).

  8. Timing-Free Blind Multiuser Detection for Multicarrier DS/CDMA Systems with Multiple Antennae

    Directory of Open Access Journals (Sweden)

    Stefano Buzzi

    2004-05-01

    Full Text Available The problem of blind multiuser detection for an asynchronous multicarrier DS-CDMA system employing multiple transmit and receive antennae over a Rayleigh fading channel is considered in this paper. The solutions that we develop require prior knowledge of the spreading code of the user to be decoded only, while no further information either on the user to be decoded or on the other active users is required. Several combining rules for the observables at the output of each receive antenna are proposed and assessed, and the implications of the different options are studied in depth in terms of both detection performance and computational complexity. A closed form expression is also derived for the conditional error probability and a lower bound for the near-far resistance is provided. Results confirm that the proposed blind receivers can cope with both multiple access interference suppression and channel estimation at the price of a limited performance loss as compared to the ideal linear receivers which assume perfect channel state information.

  9. Restrictive partially blind signature for resource-constrained information systems

    NARCIS (Netherlands)

    Qiu, Weidong; Gong, Zheng; Liu, Bozhong; Long, Yu; Chen, Kefei

    2010-01-01

    Restrictive partially blind signature, which is designed for privacy oriented information systems, allows a user to obtain a blind signature from a signer whilst the blind message must obey some certain rules. In order to reduce storage and communication costs, several public-key cryptosystems are

  10. A Dual Decomposition Approach to Partial Crosstalk Cancelation in a Multiuser DMT-xDSL Environment

    Directory of Open Access Journals (Sweden)

    Verlinden Jan

    2007-01-01

    Full Text Available In modern DSL systems, far-end crosstalk is a major source of performance degradation. Crosstalk cancelation schemes have been proposed to mitigate the effect of crosstalk. However, the complexity of crosstalk cancelation grows with the square of the number of lines in the binder. Fortunately, most of the crosstalk originates from a limited number of lines and, for DMT-based xDSL systems, on a limited number of tones. As a result, a fraction of the complexity of full crosstalk cancelation suffices to cancel most of the crosstalk. The challenge is then to determine which crosstalk to cancel on which tones, given a complexity constraint. This paper presents an algorithm based on a dual decomposition to optimally solve this problem. The proposed algorithm naturally incorporates rate constraints and the complexity of the algorithm compares favorably to a known resource allocation algorithm, where a multiuser extension is made to incorporate the rate constraints.

  11. Quality of life in blind and partially sighted people

    OpenAIRE

    Vuletić, Gorka; Šarlija, Tea; Benjak, Tomislav

    2016-01-01

    The aim of this research was to examine the subjective quality of life in blind and partially sighted people in relation to the type of impairment, duration of impairment and participation in psychosocial rehabilitation. The study used a sociodemographic and health questionnaire, and the Personal Wellbeing Index for adults to examine participant satisfaction with different life domains. The results have shown that subjective quality of life in blind and partially sighted people is within the ...

  12. Comparison of Quality of Life and Social Skills between Students with Visual Problems (Blind and Partially Blind) and Normal Students

    OpenAIRE

    Fereshteh Kordestani; Azam Daneshfar; Davood Roustaee

    2014-01-01

    This study aimed to compare the quality of life and social skills between students who are visually impaired (blind and partially blind) and normal students. The population consisted of all students with visual problems (blind and partially blind) and normal students in secondary schools in Tehran in the academic year 2013-2014. Using a multi-stage random sampling method, 40 students were selected from each group. The SF-36s quality of life questionnaire and Foster and Inderbitzen social skil...

  13. Partially blind instantly decodable network codes for lossy feedback environment

    KAUST Repository

    Sorour, Sameh

    2014-09-01

    In this paper, we study the multicast completion and decoding delay minimization problems for instantly decodable network coding (IDNC) in the case of lossy feedback. When feedback loss events occur, the sender falls into uncertainties about packet reception at the different receivers, which forces it to perform partially blind selections of packet combinations in subsequent transmissions. To determine efficient selection policies that reduce the completion and decoding delays of IDNC in such an environment, we first extend the perfect feedback formulation in our previous works to the lossy feedback environment, by incorporating the uncertainties resulting from unheard feedback events in these formulations. For the completion delay problem, we use this formulation to identify the maximum likelihood state of the network in events of unheard feedback and employ it to design a partially blind graph update extension to the multicast IDNC algorithm in our earlier work. For the decoding delay problem, we derive an expression for the expected decoding delay increment for any arbitrary transmission. This expression is then used to find the optimal policy that reduces the decoding delay in such lossy feedback environment. Results show that our proposed solutions both outperform previously proposed approaches and achieve tolerable degradation even at relatively high feedback loss rates.

  14. Comparison of isokinetic peak force and power in adults with partial and total blindness.

    Science.gov (United States)

    Horvat, Michael; Ray, Christopher; Nocera, Joe; Croce, Ron

    2006-08-01

    For many populations the ability to move efficiently is compromised by an impaired muscular functioning. Strength development is necessary to overcome the effects of gravity to maintain posture and generate movement responses for mobility. The strength and power capabilities of individuals with total blindness (n = 12) were compared to those with partial vision (n = 12) to evaluate effects of vision on performance. Results indicate that (1) no significant differences were apparent between total blindness and partial vision, (2) significant sex differences were evident in each group, and (3) better performance was apparent at lower velocities. It was concluded that physical performance in individuals with blindness and partial vision are equally deficient.

  15. ICT in Portuguese Reference Schools for the Education of Blind and Partially Sighted Students

    Science.gov (United States)

    Ramos, Sara Isabel Moca; de Andrade, António Manuel Valente

    2016-01-01

    Technology has become an essential component in our society and considering its impact in the educational system, Information and Communication Technologies (ICT) cannot be dissociated from the educational process and, in particular, from pedagogical practices adopted for students who are blind or partially sighted. This study focuses on…

  16. Leading causes of certification for blindness and partial sight in England & Wales

    Directory of Open Access Journals (Sweden)

    Wormald Richard

    2006-03-01

    Full Text Available Abstract Background Prevention of visual impairment is an international priority agreed at the World Health Assembly of 2002- yet many countries lack contemporary data about incidence and causes from which priorities for prevention, treatment and management can be identified. Methods Registration as blind or partially-sighted in England and Wales is voluntary and is initiated by certification by a consultant ophthalmologist. From all certificates completed during the year April 1999 to March 2000, the main cause of visual loss was ascertained where possible and here we present information on the leading causes observed and comment on changes in the three leading causes since the last analysis conducted for 1990–1991 data. Results 13788 people were certified as blind, 19107 were certified as partially sighted. The majority of certifications were in the older age groups. The most commonly recorded main cause of certifications for both blindness (57.2 % and partial sight (56 % was degeneration of the macula and posterior pole which largely comprises age-related macular degeneration. Glaucoma and diabetic retinopathy were the next most commonly recorded main causes. Overall, the age specific incidence of all three leading causes has increased since 1990–1991 – with changes in diabetic retinopathy being the most marked – particularly in the over 65's where figures have more than doubled. Conclusion The numbers of individuals per 100,000 population being certified blind or partially sighted due to the three leading causes – AMD, diabetic retinopathy and glaucoma have increased since 1990. This may to some extent be explained by improved ascertainment. The process of registration for severe visual impairment in England and Wales is currently undergoing review. Efforts must be made to ensure that routine collection of data on causes of severe visual impairment is continued, particularly in this age of improved technology, to allow such trends

  17. University multi-user facility survey-2010.

    Science.gov (United States)

    Riley, Melissa B

    2011-12-01

    Multi-user facilities serve as a resource for many universities. In 2010, a survey was conducted investigating possible changes and successful characteristics of multi-user facilities, as well as identifying problems in facilities. Over 300 surveys were e-mailed to persons identified from university websites as being involved with multi-user facilities. Complete responses were received from 36 facilities with an average of 20 years of operation. Facilities were associated with specific departments (22%), colleges (22%), and university research centers (8.3%) or were not affiliated with any department or college within the university (47%). The five most important factors to succeed as a multi-user facility were: 1) maintaining an experienced, professional staff in an open atmosphere; 2) university-level support providing partial funding; 3) broad client base; 4) instrument training programs; and 5) an effective leader and engaged strategic advisory group. The most significant problems were: 1) inadequate university financial support and commitment; 2) problems recovering full service costs from university subsidies and user fees; 3) availability of funds to repair and upgrade equipment; 4) inability to retain highly qualified staff; and 5) unqualified users dirtying/damaging equipment. Further information related to these issues and to fee structure was solicited. Overall, there appeared to be a decline in university support for facilities and more emphasis on securing income by serving clients outside of the institution and by obtaining grants from entities outside of the university.

  18. Educational Applications for Blind and Partially Sighted Pupils Based on Speech Technologies for Serbian

    Science.gov (United States)

    Lučić, Branko; Ostrogonac, Stevan; Vujnović Sedlar, Nataša; Sečujski, Milan

    2015-01-01

    The inclusion of persons with disabilities has always represented an important issue. Advancements within the field of computer science have enabled the development of different types of aids, which have significantly improved the quality of life of the disabled. However, for some disabilities, such as visual impairment, the purpose of these aids is to establish an alternative communication channel and thus overcome the user's disability. Speech technologies play the crucial role in this process. This paper presents the ongoing efforts to create a set of educational applications based on speech technologies for Serbian for the early stages of education of blind and partially sighted children. Two educational applications dealing with memory exercises and comprehension of geometrical shapes are presented, along with the initial tests results obtained from research including visually impaired pupils. PMID:26171422

  19. Educational Applications for Blind and Partially Sighted Pupils Based on Speech Technologies for Serbian.

    Science.gov (United States)

    Lučić, Branko; Ostrogonac, Stevan; Vujnović Sedlar, Nataša; Sečujski, Milan

    2015-01-01

    The inclusion of persons with disabilities has always represented an important issue. Advancements within the field of computer science have enabled the development of different types of aids, which have significantly improved the quality of life of the disabled. However, for some disabilities, such as visual impairment, the purpose of these aids is to establish an alternative communication channel and thus overcome the user's disability. Speech technologies play the crucial role in this process. This paper presents the ongoing efforts to create a set of educational applications based on speech technologies for Serbian for the early stages of education of blind and partially sighted children. Two educational applications dealing with memory exercises and comprehension of geometrical shapes are presented, along with the initial tests results obtained from research including visually impaired pupils.

  20. Exploring the Musical Interests and Abilities of Blind and Partially Sighted Children and Young People with Retinopathy of Prematurity

    Science.gov (United States)

    Matawa, Christina

    2009-01-01

    This study explores the musical interests and talents of children and young people who are blind or partially sighted as a result of retinopathy of prematurity (RoP). The results from questionnaires completed by 37 parents were analysed using methods drawn from Ockelford et al.'s (2006) study of the musical interests and abilities of children with…

  1. Blind separation of overlapping partials in harmonic musical notes using amplitude and phase reconstruction

    Science.gov (United States)

    de León, Jesús Ponce; Beltrán, José Ramón

    2012-12-01

    In this study, a new method of blind audio source separation (BASS) of monaural musical harmonic notes is presented. The input (mixed notes) signal is processed using a flexible analysis and synthesis algorithm (complex wavelet additive synthesis, CWAS), which is based on the complex continuous wavelet transform. When the harmonics from two or more sources overlap in a certain frequency band (or group of bands), a new technique based on amplitude similarity criteria is used to obtain an approximation to the original partial information. The aim is to show that the CWAS algorithm can be a powerful tool in BASS. Compared with other existing techniques, the main advantages of the proposed algorithm are its accuracy in the instantaneous phase estimation, its synthesis capability and that the only input information needed is the mixed signal itself. A set of synthetically mixed monaural isolated notes have been analyzed using this method, in eight different experiments: the same instrument playing two notes within the same octave and two harmonically related notes (5th and 12th intervals), two different musical instruments playing 5th and 12th intervals, two different instruments playing non-harmonic notes, major and minor chords played by the same musical instrument, three different instruments playing non-harmonically related notes and finally the mixture of a inharmonic instrument (piano) and one harmonic instrument. The results obtained show the strength of the technique.

  2. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

    2012-01-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  3. Multiuser switched diversity scheduling schemes

    KAUST Repository

    Shaqfeh, Mohammad

    2012-09-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed, and ordered scheduling mechanism. The main idea behind these schemes is that slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we characterize the achievable rate region of multiuser switched diversity systems and compare it with the rate region of full feedback multiuser diversity systems. We propose also a novel proportional fair multiuser switched-based scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the feedback thresholds. We finally demonstrate by numerical examples that switched-diversity scheduling schemes operate within 0.3 bits/sec/Hz from the ultimate network capacity of full feedback systems in Rayleigh fading conditions. © 2012 IEEE.

  4. Blind Deconvolution of Anisoplanatic Images Collected by a Partially Coherent Imaging System

    National Research Council Canada - National Science Library

    MacDonald, Adam

    2004-01-01

    ... have limited emissivity or reflectivity. This research proposes a novel blind deconvolution algorithm that is based on a maximum a posteriori Bayesian estimator constructed upon a physically based statistical model for the intensity...

  5. Comparison of blind imaging performance of Fizeau and Michelson type arrays for a partially resolved object

    NARCIS (Netherlands)

    Van der Avoort, C.; Den Herder, J.W.; Braat, J.

    2005-01-01

    This paper compares two well-known types of interferometer arrays for optical aperture synthesis. An analytical model for both types describes the expected output, in terms of photon counts. The goal is to characterize the performance of both types of array for blind imaging of a wide-field or

  6. Understanding the requirements of geographical data for blind and partially sighted people to make journeys more independently.

    Science.gov (United States)

    Chandler, Edward; Worsfold, John

    2013-11-01

    Previous research has highlighted that blind and partially sighted people find various factors inhibit their abilities to make journeys. This paper proposes that the lack of accurate, appropriate and usable geographical data is one of the reasons for this and these can be tracked back to core human factors issues such as situational awareness, mental workload and environmental ergonomics. Following a review of applicable literature a hierarchical task analysis was performed to better understand the problems in terms of the complexity of various journey types and to identify the geographical data requirements in order to make successful journeys. The task analysis produced a number of results including highlighting four underlying principles which have an impact on the data requirements during any given journey. Finally the need for accessible and accurate geographical data requirements is introduced as a result of the literature review and the task analysis. These highlight the information required in order to facilitate more accessible travel for blind and partially sighted people by providing geographical information about their surroundings in a relevant, meaningful and usable way. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  7. Exploring Intrinsic and Extrinsic Motivations to Participate in a Crowdsourcing Project to Support Blind and Partially Sighted Students.

    Science.gov (United States)

    Layas, Fatma; Petrie, Helen

    2016-01-01

    There have been a number of crowdsourcing projects to support people with disabilities. However, there is little exploration of what motivates people to participate in such crowdsourcing projects. In this study we investigated how different motivational factors can affect the participation of people in a crowdsourcing project to support visually disabled students. We are developing "DescribeIT", a crowdsourcing project to support blind and partially students by having sighted people describe images in digital learning resources. We investigated participants' behavior of the DescribeIT project using three conditions: one intrinsic motivation condition and two extrinsic motivation conditions. The results showed that participants were significantly intrinsically motivated to participate in the DescribeIT project. In addition, participants' intrinsic motivation dominated the effect of the two extrinsic motivational factors in the extrinsic conditions.

  8. Multiuser hybrid switched-selection diversity systems

    KAUST Repository

    Shaqfeh, Mohammad; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

    2011-01-01

    system provides flexibility in trading-off the channel information feedback overhead with the prospected multiuser diversity gains. The users are clustered into groups, and the users' groups are ordered into a sequence. Per-group feedback thresholds

  9. The review of the organization of library services for the blind and partially sighted in the selected countries

    Directory of Open Access Journals (Sweden)

    Damjana Vovk

    2011-01-01

    Full Text Available Purpose: Models of organization of library services for the blind and partially sighted from the view of special and public librarianship in selected countries were examined.In addition, theoretical and legislative frameworks, professional guidelines and trends are explored. Some terminological inconsistencies and obstacles in performing the services are also presented.Methodology/approach: The explorative-comparative study carried in the years 2008-2010 includes the comparative analysis of data acquired by the survey and literature desktop research. The research sample included 14 countries - eleven European countries, USA,Australia, and Canada.Results: The findings show great varieties among the selected countries, however,there is the trend of moving the organization of services based on a private charitable association to the formalized state supported system. The majority of countries have applied the centralized model with one specialized (national library. There is rarely a case of formal inclusion of public libraries in the organization of services. Recent major professional interests in the field of providing library services to visually impaired are broadening the copyright exceptions and user groups, and the implementation of information technology for bigger production of alternative formats and availability of library materials.Research limitation: The low rate of survey response and the differences in the organization of library services influenced on the lack of data and low level of data comparability.Originality/practical implications: The results are useful for designing a model of library services in Slovenia.

  10. A reduced feedback proportional fair multiuser scheduling scheme

    KAUST Repository

    Shaqfeh, Mohammad; Alnuweiri, Hussein M.; Alouini, Mohamed-Slim

    2011-01-01

    . A slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we propose a novel proportional fair multiuser switched

  11. Differential impact of partial cortical blindness on gaze strategies when sitting and walking - an immersive virtual reality study.

    Science.gov (United States)

    Iorizzo, Dana B; Riley, Meghan E; Hayhoe, Mary; Huxlin, Krystel R

    2011-05-25

    The present experiments aimed to characterize the visual performance of subjects with long-standing, unilateral cortical blindness when walking in a naturalistic, virtual environment. Under static, seated testing conditions, cortically blind subjects are known to exhibit compensatory eye movement strategies. However, they still complain of significant impairment in visual detection during navigation. To assess whether this is due to a change in compensatory eye movement strategy between sitting and walking, we measured eye and head movements in subjects asked to detect peripherally-presented, moving basketballs. When seated, cortically blind subjects detected ∼80% of balls, while controls detected almost all balls. Seated blind subjects did not make larger head movements than controls, but they consistently biased their fixation distribution towards their blind hemifield. When walking, head movements were similar in the two groups, but the fixation bias decreased to the point that fixation distribution in cortically blind subjects became similar to that in controls - with one major exception: at the time of basketball appearance, walking controls looked primarily at the far ground, in upper quadrants of the virtual field of view; cortically blind subjects looked significantly more at the near ground, in lower quadrants of the virtual field. Cortically blind subjects detected only 58% of the balls when walking while controls detected ∼90%. Thus, the adaptive gaze strategies adopted by cortically blind individuals as a compensation for their visual loss are strongest and most effective when seated and stationary. Walking significantly alters these gaze strategies in a way that seems to favor walking performance, but impairs peripheral target detection. It is possible that this impairment underlies the experienced difficulty of those with cortical blindness when navigating in real life. Copyright © 2011 Elsevier Ltd. All rights reserved.

  12. Homeopathy for Depression - DEP-HOM: study protocol for a randomized, partially double-blind, placebo controlled, four armed study

    Science.gov (United States)

    2011-01-01

    Background Homeopathy is often sought by patients with depression. In classical homeopathy, the treatment consists of two main elements: the case history and the prescription of an individually selected homeopathic remedy. Previous data suggest that individualized homeopathic Q-potencies were not inferior to the antidepressant fluoxetine in a sample of patients with moderate to severe depression. However, the question remains whether individualized homeopathic Q-potencies and/or the type of the homeopathic case history have a specific therapeutical effect in acute depression as this has not yet been investigated. The study aims to assess the two components of individualized homeopathic treatment for acute depression, i.e., to investigate the specific effect of individualized Q-potencies versus placebo and to investigate the effect of different approaches to the homeopathic case history. Methods/Design A randomized, partially double-blind, placebo-controlled, four-armed trial using a 2 × 2 factorial design with a six-week study duration per patient will be performed. 228 patients diagnosed with major depression (moderate episode) by a psychiatrist will be included. The primary endpoint is the total score on the 17-item Hamilton Depression Rating Scale after six weeks. Secondary end points are: Hamilton Depression Rating Scale total score after two and four weeks; response and remission rates, Beck Depression inventory total score, quality of life and safety at two, four and six weeks. Statistical analyses will be by intention-to-treat. The main endpoint will be analysed by a two-factorial analysis of covariance. Within this model generalized estimation equations will be used to estimate differences between verum and placebo, and between both types of case history. Discussion For the first time this study evaluates both the specific effect of homeopathic medicines and of a homeopathic case taking in patients with depression. It is an attempt to deal with the

  13. Heart to Heart: Parents of Blind and Partially Sighted Children Talk about Their Feelings = De Corazon a Corazon: Padres de Ninos Ciegos y Parcialmente Ciegos Hablan acerca de Sus Sentimientos.

    Science.gov (United States)

    Blind Childrens Center, Los Angeles, CA.

    English and Spanish versions of this booklet describe typical feelings experienced by parents of blind and partially sighted children. Experiences are cited including first feelings of shock and confusion, days of dramatic ups and downs, need to find a reason for the blindness, self doubts and anxiety, and reactions from strangers. In closing, the…

  14. On Low-Complexity Full-diversity Detection In Multi-User MIMO Multiple-Access Channels

    KAUST Repository

    Ismail, Amr

    2014-01-28

    Multiple-input multiple-output (MIMO) techniques are becoming commonplace in recent wireless communication standards. This newly introduced dimension (i.e., space) can be efficiently used to mitigate the interference in the multi-user MIMO context. In this paper, we focus on the uplink of a MIMO multiple access channel (MAC) where perfect channel state information (CSI) is only available at the destination. We provide new sufficient conditions for a wide range of space-time block codes (STBC)s to achieve full-diversity under partial interference cancellation group decoding (PICGD) with or without successive interference cancellation (SIC) for completely blind users. Interference cancellation (IC) schemes for two and three users are then provided and shown to satisfy the full-diversity criteria. Beside the complexity reduction due to the fact that PICGD enables separate decoding of distinct users without sacrificing the diversity gain, further reduction of the decoding complexity may be obtained. In fact, thanks to the structure of the proposed schemes, the real and imaginary parts of each user\\'s symbols may be decoupled without any loss of performance. Our new IC scheme is shown to outperform recently proposed two-user IC scheme especially for high spectral efficiency while requiring significantly less decoding complexity.

  15. On Low-Complexity Full-diversity Detection In Multi-User MIMO Multiple-Access Channels

    KAUST Repository

    Ismail, Amr; Alouini, Mohamed-Slim

    2014-01-01

    Multiple-input multiple-output (MIMO) techniques are becoming commonplace in recent wireless communication standards. This newly introduced dimension (i.e., space) can be efficiently used to mitigate the interference in the multi-user MIMO context. In this paper, we focus on the uplink of a MIMO multiple access channel (MAC) where perfect channel state information (CSI) is only available at the destination. We provide new sufficient conditions for a wide range of space-time block codes (STBC)s to achieve full-diversity under partial interference cancellation group decoding (PICGD) with or without successive interference cancellation (SIC) for completely blind users. Interference cancellation (IC) schemes for two and three users are then provided and shown to satisfy the full-diversity criteria. Beside the complexity reduction due to the fact that PICGD enables separate decoding of distinct users without sacrificing the diversity gain, further reduction of the decoding complexity may be obtained. In fact, thanks to the structure of the proposed schemes, the real and imaginary parts of each user's symbols may be decoupled without any loss of performance. Our new IC scheme is shown to outperform recently proposed two-user IC scheme especially for high spectral efficiency while requiring significantly less decoding complexity.

  16. Multiuser hybrid switched-selection diversity systems

    KAUST Repository

    Shaqfeh, Mohammad

    2011-09-01

    A new multiuser scheduling scheme is proposed and analyzed in this paper. The proposed system combines features of conventional full-feedback selection-based diversity systems and reduced-feedback switch-based diversity systems. The new hybrid system provides flexibility in trading-off the channel information feedback overhead with the prospected multiuser diversity gains. The users are clustered into groups, and the users\\' groups are ordered into a sequence. Per-group feedback thresholds are used and optimized to maximize the system overall achievable rate. The proposed hybrid system applies switched diversity criterion to choose one of the groups, and a selection criterion to decide the user to be scheduled from the chosen group. Numerical results demonstrate that the system capacity increases as the number of users per group increases, but at the cost of more required feedback messages. © 2011 IEEE.

  17. Multiuser Random Coding Techniques for Mismatched Decoding

    OpenAIRE

    Scarlett, Jonathan; Martinez, Alfonso; Guillén i Fàbregas, Albert

    2016-01-01

    This paper studies multiuser random coding techniques for channel coding with a given (possibly suboptimal) decoding rule. For the mismatched discrete memoryless multiple-access channel, an error exponent is obtained that is tight with respect to the ensemble average, and positive within the interior of Lapidoth's achievable rate region. This exponent proves the ensemble tightness of the exponent of Liu and Hughes in the case of maximum-likelihood decoding. An equivalent dual form of Lapidoth...

  18. Partial recovery of visual-spatial remapping of touch after restoring vision in a congenitally blind man.

    Science.gov (United States)

    Ley, Pia; Bottari, Davide; Shenoy, Bhamy H; Kekunnaya, Ramesh; Röder, Brigitte

    2013-05-01

    In an initial processing step, sensory events are encoded in modality specific representations in the brain but seem to be automatically remapped into a supra-modal, presumably visual-external frame of reference. To test whether there is a sensitive phase in the first years of life during which visual input is crucial for the acquisition of this remapping process, we tested a single case of a congenitally blind man whose sight was restored after the age of two years. HS performed a tactile temporal order judgment task (TOJ) which required judging the temporal order of two tactile stimuli, one presented to each index finger. In addition, a visual-tactile cross-modal congruency task was run, in which spatially congruent and spatially incongruent visual distractor stimuli were presented together with tactile stimuli. The tactile stimuli had to be localized. Both tasks were performed with an uncrossed and a crossed hand posture. Similar to congenitally blind individuals HS did not show a crossing effect in the tactile TOJ task suggesting an anatomical rather than visual-external coding of touch. In the visual-tactile task, however, external remapping of touch was observed though incomplete compared to sighted controls. These data support the hypothesis of a sensitive phase for the acquisition of an automatic use of visual-spatial representations for coding tactile input. Nonetheless, these representations seem to be acquired to some extent after the end of congenital blindness but seem to be recruited only in the context of visual stimuli and are used with a reduced efficiency. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. The Effects of the Bali Yoga Program for Breast Cancer Patients on Chemotherapy-Induced Nausea and Vomiting: Results of a Partially Randomized and Blinded Controlled Trial.

    Science.gov (United States)

    Anestin, Annélie S; Dupuis, Gilles; Lanctôt, Dominique; Bali, Madan

    2017-10-01

    Complementary and alternative medicine has been shown to be beneficial in reducing chemotherapy-induced nausea and vomiting. However, conclusive results are lacking in order to confirm its usefulness. The purpose of this study was to determine whether a standardized yoga intervention could reduce these adverse symptoms. This was a partially randomized and blinded controlled trial comparing a standardized yoga intervention with standard care. Eligible patients were adults diagnosed with stages I to III breast cancer receiving chemotherapy. Patients randomized to the experimental group participated in an 8-week yoga program. There was no significant difference between the experimental and control groups on chemotherapy-induced nausea and vomiting after 8 weeks. Results suggest the yoga program is not beneficial in managing these adverse symptoms. However, considering preliminary evidence suggesting yoga's beneficial impact in cancer symptom management, methodological limitations should be explored and additional studies should be conducted.

  20. Aspects of multiuser MIMO for cell throughput maximization

    DEFF Research Database (Denmark)

    Bauch, Gerhard; Tejera, Pedro; Guthy, Christian

    2007-01-01

    We consider a multiuser MIMO downlink scenario where the resources in time, frequency and space are allocated such that the total cell throughput is maximized. This is achieved by exploiting multiuser diversity, i.e. the physical resources are allocated to the user with the highest SNR. We assume...

  1. Multi-user data acquisition environment

    International Nuclear Information System (INIS)

    Storch, N.A.

    1983-01-01

    The typical data acquisition environment involves data collection and monitoring by a single user. However, in order to support experiments on the Mars facility at Lawrence Livermore National Laboratory, we have had to create a multi-user data acquisition environment where any user can control the data acquisition and several users can monitor and analyze data being collected in real time. This paper describes how we accomplished this on an HP A600 computer. It focuses on the overall system description and user communication with the tasks within the system. Our current implementation is one phase of a long-term software development project

  2. Nonlinear Multiuser Receiver for Optimized Chaos-Based DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    S. Shaerbaf

    2011-09-01

    Full Text Available Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS-CDMA systems, chaos-based CDMA systems suffer from multi-user interference (MUI due to other users transmitting in the cell. In this paper, we propose a novel method based on radial basis function (RBF for both blind and non-blind multiuser detection in chaos-based DS-CDMA systems. We also propose a new method for optimizing generation of binary chaotic sequences using Genetic Algorithm. Simulation results show that our proposed nonlinear receiver with optimized chaotic sequences outperforms in comparison to other conventional detectors such as a single-user detector, decorrelating detector and minimum mean square error detector, particularly for under-loaded CDMA condition, which the number of active users is less than processing gain.

  3. Transmitter Layering for Multiuser MIMO Systems

    Directory of Open Access Journals (Sweden)

    Schlegel Christian

    2008-01-01

    Full Text Available Abstract A novel structure for multiple antenna transmissions utilizing space-time dispersion is proposed, where the original data stream is divided into substreams which are modulated onto all available transmit antennas using stream-specific transmit signature sequences. In order to achieve this, the transmit antennas are partitioned into groups of antennas, called partitions. The signals from the data streams are independently interleaved by partition over the entire transmission frame. The interleaved partitions are then added over all substreams prior to transmission over the MIMO channel. At the receiver, a low-complexity iterative detector adapted from recent CDMA multiuser detection research is used. It is shown that with careful substream power assignments this transmission methodology can efficiently utilize the capacity of rank-deficient channels as it can approach the capacity limits of the multiple antenna channel closely over the entire range of available signal-to-noise ratios and system sizes. This transmission methodology and receiver structure are then applied to multiuser MIMO systems where several multiple antenna terminals communicate concurrently to a joint receiver. It is shown that different received power levels from the different MIMO terminals can be beneficial and that higher spectral efficiencies can be achieved than in the single-terminal case.

  4. Transmitter Layering for Multiuser MIMO Systems

    Directory of Open Access Journals (Sweden)

    Zachary Bagley

    2008-03-01

    Full Text Available A novel structure for multiple antenna transmissions utilizing space-time dispersion is proposed, where the original data stream is divided into K substreams which are modulated onto all available transmit antennas using stream-specific transmit signature sequences. In order to achieve this, the transmit antennas are partitioned into M groups of antennas, called partitions. The signals from the K data streams are independently interleaved by partition over the entire transmission frame. The interleaved partitions are then added over all K substreams prior to transmission over the MIMO channel. At the receiver, a low-complexity iterative detector adapted from recent CDMA multiuser detection research is used. It is shown that with careful substream power assignments this transmission methodology can efficiently utilize the capacity of rank-deficient channels as it can approach the capacity limits of the multiple antenna channel closely over the entire range of available signal-to-noise ratios and system sizes. This transmission methodology and receiver structure are then applied to multiuser MIMO systems where several multiple antenna terminals communicate concurrently to a joint receiver. It is shown that different received power levels from the different MIMO terminals can be beneficial and that higher spectral efficiencies can be achieved than in the single-terminal case.

  5. On the performance of spectrum sharing systems with two-way relaying and multiuser diversity

    KAUST Repository

    Yang, Liang

    2012-08-01

    In this letter, we consider a spectrum sharing network with two-way relaying and multi-user diversity. More specifically, one secondary transmitter with the best channel quality is selected and splits its partial power to relay its received signals to the primary users by using the amplify-and-forward relaying protocol. We derive a tight approximation for the resulting outage probability. Based on this formula, the performance of the spectral sharing region and the cell coverage are analyzed. Numerical results are given to verify our analysis and are discussed to illustrate the advantages of our newly proposed scheme. © 1997-2012 IEEE.

  6. Compressive Sensing for Feedback Reduction in Wireless Multiuser Networks

    KAUST Repository

    Elkhalil, Khalil

    2015-01-01

    User/relay selection is a simple technique that achieves spatial diversity in multiuser networks. However, for user/relay selection algorithms to make a selection decision, channel state information (CSI) from all cooperating users/relays is usually

  7. Mindfulness-based stress reduction compared with cognitive behavioral therapy for the treatment of insomnia comorbid with cancer: a randomized, partially blinded, noninferiority trial.

    Science.gov (United States)

    Garland, Sheila N; Carlson, Linda E; Stephens, Alisa J; Antle, Michael C; Samuels, Charles; Campbell, Tavis S

    2014-02-10

    Our study examined whether mindfulness-based stress reduction (MBSR) is noninferior to cognitive behavioral therapy for insomnia (CBT-I) for the treatment of insomnia in patients with cancer. This was a randomized, partially blinded, noninferiority trial involving patients with cancer with insomnia recruited from a tertiary cancer center in Calgary, Alberta, Canada, from September 2008 to March 2011. Assessments were conducted at baseline, after the program, and after 3 months of follow-up. The noninferiority margin was 4 points measured by the Insomnia Severity Index. Sleep diaries and actigraphy measured sleep onset latency (SOL), wake after sleep onset (WASO), total sleep time (TST), and sleep efficiency. Secondary outcomes included sleep quality, sleep beliefs, mood, and stress. Of 327 patients screened, 111 were randomly assigned (CBT-I, n = 47; MBSR, n = 64). MBSR was inferior to CBT-I for improving insomnia severity immediately after the program (P = .35), but MBSR demonstrated noninferiority at follow-up (P = .02). Sleep diary-measured SOL was reduced by 22 minutes in the CBT-I group and by 14 minutes in the MBSR group at follow-up. Similar reductions in WASO were observed for both groups. TST increased by 0.60 hours for CBT-I and 0.75 hours for MBSR. CBT-I improved sleep quality (P treatment of insomnia.

  8. A Novel Partial Discharge Ultra-High Frequency Signal De-Noising Method Based on a Single-Channel Blind Source Separation Algorithm

    Directory of Open Access Journals (Sweden)

    Liangliang Wei

    2018-02-01

    Full Text Available To effectively de-noise the Gaussian white noise and periodic narrow-band interference in the background noise of partial discharge ultra-high frequency (PD UHF signals in field tests, a novel de-noising method, based on a single-channel blind source separation algorithm, is proposed. Compared with traditional methods, the proposed method can effectively de-noise the noise interference, and the distortion of the de-noising PD signal is smaller. Firstly, the PD UHF signal is time-frequency analyzed by S-transform to obtain the number of source signals. Then, the single-channel detected PD signal is converted into multi-channel signals by singular value decomposition (SVD, and background noise is separated from multi-channel PD UHF signals by the joint approximate diagonalization of eigen-matrix method. At last, the source PD signal is estimated and recovered by the l1-norm minimization method. The proposed de-noising method was applied on the simulation test and field test detected signals, and the de-noising performance of the different methods was compared. The simulation and field test results demonstrate the effectiveness and correctness of the proposed method.

  9. On Performance of Linear Multiuser Detectors for Wireless Multimedia Applications

    Science.gov (United States)

    Agarwal, Rekha; Reddy, B. V. R.; Bindu, E.; Nayak, Pinki

    In this paper, performance of different multi-rate schemes in DS-CDMA system is evaluated. The analysis of multirate linear multiuser detectors with multiprocessing gain is analyzed for synchronous Code Division Multiple Access (CDMA) systems. Variable data rate is achieved by varying the processing gain. Our conclusion is that bit error rate for multirate and single rate systems can be made same with a tradeoff with number of users in linear multiuser detectors.

  10. Multiuser Collaboration with Networked Mobile Devices

    Science.gov (United States)

    Tso, Kam S.; Tai, Ann T.; Deng, Yong M.; Becks, Paul G.

    2006-01-01

    In this paper we describe a multiuser collaboration infrastructure that enables multiple mission scientists to remotely and collaboratively interact with visualization and planning software, using wireless networked personal digital assistants(PDAs) and other mobile devices. During ground operations of planetary rover and lander missions, scientists need to meet daily to review downlinked data and plan science activities. For example, scientists use the Science Activity Planner (SAP) in the Mars Exploration Rover (MER) mission to visualize downlinked data and plan rover activities during the science meetings [1]. Computer displays are projected onto large screens in the meeting room to enable the scientists to view and discuss downlinked images and data displayed by SAP and other software applications. However, only one person can interact with the software applications because input to the computer is limited to a single mouse and keyboard. As a result, the scientists have to verbally express their intentions, such as selecting a target at a particular location on the Mars terrain image, to that person in order to interact with the applications. This constrains communication and limits the returns of science planning. Furthermore, ground operations for Mars missions are fundamentally constrained by the short turnaround time for science and engineering teams to process and analyze data, plan the next uplink, generate command sequences, and transmit the uplink to the vehicle [2]. Therefore, improving ground operations is crucial to the success of Mars missions. The multiuser collaboration infrastructure enables users to control software applications remotely and collaboratively using mobile devices. The infrastructure includes (1) human-computer interaction techniques to provide natural, fast, and accurate inputs, (2) a communications protocol to ensure reliable and efficient coordination of the input devices and host computers, (3) an application

  11. Tai Chi Chih Compared With Cognitive Behavioral Therapy for the Treatment of Insomnia in Survivors of Breast Cancer: A Randomized, Partially Blinded, Noninferiority Trial.

    Science.gov (United States)

    Irwin, Michael R; Olmstead, Richard; Carrillo, Carmen; Sadeghi, Nina; Nicassio, Perry; Ganz, Patricia A; Bower, Julienne E

    2017-08-10

    Purpose Cognitive behavioral therapy for insomnia (CBT-I) and Tai Chi Chih (TCC), a movement meditation, improve insomnia symptoms. Here, we evaluated whether TCC is noninferior to CBT-I for the treatment of insomnia in survivors of breast cancer. Patients and Methods This was a randomized, partially blinded, noninferiority trial that involved survivors of breast cancer with insomnia who were recruited from the Los Angeles community from April 2008 to July 2012. After a 2-month phase-in period with repeated baseline assessment, participants were randomly assigned to 3 months of CBT-I or TCC and evaluated at months 2, 3 (post-treatment), 6, and 15 (follow-up). Primary outcome was insomnia treatment response-that is, marked clinical improvement of symptoms by the Pittsburgh Sleep Quality Index-at 15 months. Secondary outcomes were clinician-assessed remission of insomnia; sleep quality; total sleep time, sleep onset latency, sleep efficiency, and awake after sleep onset, derived from sleep diaries; polysomnography; and symptoms of fatigue, sleepiness, and depression. Results Of 145 participants who were screened, 90 were randomly assigned (CBT-I: n = 45; TCC: n = 45). The proportion of participants who showed insomnia treatment response at 15 months was 43.7% and 46.7% in CBT-I and TCC, respectively. Tests of noninferiority showed that TCC was noninferior to CBT-I at 15 months ( P = .02) and at months 3 ( P = .02) and 6 ( P insomnia remission was 46.2% and 37.9% in CBT-I and TCC, respectively. CBT-I and TCC groups showed robust improvements in sleep quality, sleep diary measures, and related symptoms (all P insomnia. TCC, a mindful movement meditation, was found to be statistically noninferior to CBT-I, the gold standard for behavioral treatment of insomnia.

  12. The effects of the Bali Yoga Program (BYP-BC) on reducing psychological symptoms in breast cancer patients receiving chemotherapy: results of a randomized, partially blinded, controlled trial.

    Science.gov (United States)

    Lanctôt, Dominique; Dupuis, Gilles; Marcaurell, Roger; Anestin, Annélie S; Bali, Madan

    2016-12-01

    Background Several cognitive behavioral interventions have been reported to reduce psychological symptoms in breast cancer (BC) patients. The goal of this study was to evaluate the effects of a yoga intervention in reducing depression and anxiety symptoms in BC patients. Methods This study was a randomized, partially blinded, controlled trial comparing a standardized yoga intervention to standard care. It was conducted at three medical centers in Montreal, Canada. Eligible patients were women diagnosed with stage I-III BC receiving chemotherapy. Participants were randomly assigned to receive yoga intervention immediately (experimental group, n=58) or after a waiting period (n=43 control group). The Bali Yoga Program for Breast Cancer Patients (BYP-BC) consisted of 23 gentle Hatha asanas (poses), 2 prayanamas (breathing techniques), shavasanas (relaxation corpse poses) and psychoeducational themes. Participants attended eight weekly sessions lasting 90 min each and received a DVD for home practice with 20- and 40-min sessions. Participants in the wait list control group received standard care during the 8-week waiting period. Results A total of 101 participants took part in the final intention-to-treat analyses. The repeated measures analyses demonstrated that depression symptoms increased in the control group (p=0.007), while no change was reported in the BYP-BC group (p=0.29). Also, depression symptoms decreased in the WL control group after receiving the BYP-BC intervention (p=0.03). Finally, there was no statistical significance in terms of anxiety symptoms (p=0.10). Conclusions Results support the BYP-BC intervention as a beneficial means of reducing and preventing the worsening of depression symptoms during chemotherapy treatment.

  13. Multiuser MIMO Channel Measurements and Performance in a Large Office Environment

    DEFF Research Database (Denmark)

    Bauch, Gerhard; Andersen, Jørgen Bach; Guthy, Christian

    2007-01-01

    We consider a multiuser MIMO-OFDMA scheme which exploits multiuser diversity in all dimensions: time, frequency and space. The main contribution of this paper is the evaluation and explanation of multiuser MIMO in a real world scenario, i.e. a large office room, based on measured channels. We rep...

  14. A reduced feedback proportional fair multiuser scheduling scheme

    KAUST Repository

    Shaqfeh, Mohammad

    2011-12-01

    Multiuser switched-diversity scheduling schemes were recently proposed in order to overcome the heavy feedback requirements of conventional opportunistic scheduling schemes by applying a threshold-based, distributed and ordered scheduling mechanism. A slight reduction in the prospected multiuser diversity gains is an acceptable trade-off for great savings in terms of required channel-state-information feedback messages. In this work, we propose a novel proportional fair multiuser switched-diversity scheduling scheme and we demonstrate that it can be optimized using a practical and distributed method to obtain the per-user feedback thresholds. We demonstrate by numerical examples that our reduced feedback proportional fair scheduler operates within 0.3 bits/sec/Hz from the achievable rates by the conventional full feedback proportional fair scheduler in Rayleigh fading conditions. © 2011 IEEE.

  15. Adaptive Multiuser Detectors for DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Paul Jean Etienne Jeszensky

    2006-02-01

    Full Text Available This work makes a review of the main Adaptives Multi-user Detectors (MuD-Adpt for Direct Sequence - Code Division Multiple Access (DS-CDMA systems. The MuD-Adpt based on Minimum Mean Square Error (MMSE and Decorrelator (MuD-Dec are focused. Multi-user detectors show great resistance to the near-far effect and combat effectively the Multiple Access Interference (MAI. Comparative numeric results characterize the substantial performance improvement of those detectors in relation to the matched filter conventional receiver (Conv.

  16. A Multi-User Remote Academic Laboratory System

    Science.gov (United States)

    Barrios, Arquimedes; Panche, Stifen; Duque, Mauricio; Grisales, Victor H.; Prieto, Flavio; Villa, Jose L.; Chevrel, Philippe; Canu, Michael

    2013-01-01

    This article describes the development, implementation and preliminary operation assessment of Multiuser Network Architecture to integrate a number of Remote Academic Laboratories for educational purposes on automatic control. Through the Internet, real processes or physical experiments conducted at the control engineering laboratories of four…

  17. Managing Multiuser Database Buffers Using Data Mining Techniques

    NARCIS (Netherlands)

    Feng, L.; Lu, H.J.

    2004-01-01

    In this paper, we propose a data-mining-based approach to public buffer management for a multiuser database system, where database buffers are organized into two areas – public and private. While the private buffer areas contain pages to be updated by particular users, the public

  18. Multiuser MIMO: Principle, Performance in Measured Channels and Applicable Service

    DEFF Research Database (Denmark)

    Bauch, Gerhard; Tejera, Pedro; Utschick, Wolfgang

    2007-01-01

    The exploitation of multiuser diversity and the application of multiple antennas at transmitter and receiver are considered to be key technologies for future highly bandwidthefficient wireless systems. We combine both ideas in a downlink multicarrier transmission scheme where multiple users compe...

  19. Introducing ORACLE: Library Processing in a Multi-User Environment.

    Science.gov (United States)

    Queensland Library Board, Brisbane (Australia).

    Currently being developed by the State Library of Queensland, Australia, ORACLE (On-Line Retrieval of Acquisitions, Cataloguing, and Circulation Details for Library Enquiries) is a computerized library system designed to provide rapid processing of library materials in a multi-user environment. It is based on the Australian MARC format and fully…

  20. Multi-User Hardware Solutions to Combustion Science ISS Research

    Science.gov (United States)

    Otero, Angel M.

    2001-01-01

    In response to the budget environment and to expand on the International Space Station (ISS) Fluids and Combustion Facility (FCF) Combustion Integrated Rack (CIR), common hardware approach, the NASA Combustion Science Program shifted focus in 1999 from single investigator PI (Principal Investigator)-specific hardware to multi-user 'Minifacilities'. These mini-facilities would take the CIR common hardware philosophy to the next level. The approach that was developed re-arranged all the investigations in the program into sub-fields of research. Then common requirements within these subfields were used to develop a common system that would then be complemented by a few PI-specific components. The sub-fields of research selected were droplet combustion, solids and fire safety, and gaseous fuels. From these research areas three mini-facilities have sprung: the Multi-user Droplet Combustion Apparatus (MDCA) for droplet research, Flow Enclosure for Novel Investigations in Combustion of Solids (FEANICS) for solids and fire safety, and the Multi-user Gaseous Fuels Apparatus (MGFA) for gaseous fuels. These mini-facilities will develop common Chamber Insert Assemblies (CIA) and diagnostics for the respective investigators complementing the capability provided by CIR. Presently there are four investigators for MDCA, six for FEANICS, and four for MGFA. The goal of these multi-user facilities is to drive the cost per PI down after the initial development investment is made. Each of these mini-facilities will become a fixture of future Combustion Science NASA Research Announcements (NRAs), enabling investigators to propose against an existing capability. Additionally, an investigation is provided the opportunity to enhance the existing capability to bridge the gap between the capability and their specific science requirements. This multi-user development approach will enable the Combustion Science Program to drive cost per investigation down while drastically reducing the time

  1. Spared cognitive processing of visual oddballs despite delayed visual evoked potentials in patient with partial recovery of vision after 53 years of blindness

    Czech Academy of Sciences Publication Activity Database

    Kremláček, J.; Šikl, Radovan; Kuba, M.; Szanyi, J.; Kubová, Z.; Langrová, J.; Vít, F.; Šimeček, Michal; Stodůlka, P.

    2013-01-01

    Roč. 81, April (2013), s. 1-5 ISSN 0042-6989 R&D Projects: GA ČR(CZ) GAP407/12/2528 Institutional support: RVO:68081740 Keywords : visual deprivation * recovery from blindness * motion-onset VEPs * pattern-reversal VEPs * oddball ERPs * P3b Subject RIV: FH - Neurology Impact factor: 2.381, year: 2013 http://www.sciencedirect.com/science/article/pii/S0042698913000151

  2. Automatic Bluetooth testing for mobile multi-user applications

    Science.gov (United States)

    Luck, Dennis; Hörning, Henrik; Edlich, Stefan

    2008-02-01

    In this paper we present a simple approach for the development of multiuser and multimedia applications based on Bluetooth. One main obstacle for Bluetooth synchronization of mobile applications is the lack of a complete specification implementation. Nowadays these applications must be on market as fast as possible. Hence, developers must be able to test several dozens of mobile devices for their Bluetooth capability. And surprisingly, the capabilities differ not only between the Bluetooth specification 1.0 and 2.0. The current development was triggered by the development of mass applications as mobile multiuser games (e.g. Tetris). Our Application can be distributed on several mobile phones. If started, the Bluetooth applications try to connect each other and automatically start to detect device capabilities. These capabilities will be gathered and distributed to a server. The server performs statistical investigations and aggregates them to be presented as a report. The result is a faster development regarding mobile communications.

  3. Recognizing Multi-user Activities using Body Sensor Networks

    DEFF Research Database (Denmark)

    Gu, Tao; Wang, Liang; Chen, Hanhua

    2011-01-01

    The advances of wireless networking and sensor technology open up an interesting opportunity to infer human activities in a smart home environment. Existing work in this paradigm focuses mainly on recognizing activities of a single user. In this work, we address the fundamental problem...... activity classes of data—for building activity models and design a scalable, noise-resistant, Emerging Pattern based Multi-user Activity Recognizer (epMAR) to recognize both single- and multi-user activities. We develop a multi-modal, wireless body sensor network for collecting real-world traces in a smart...... home environment, and conduct comprehensive empirical studies to evaluate our system. Results show that epMAR outperforms existing schemes in terms of accuracy, scalability and robustness....

  4. Multiuser switched diversity scheduling systems with per-user threshold

    KAUST Repository

    Nam, Haewoon

    2010-05-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed and analyzed in this paper. The conventional multiuser switched diversity scheduling scheme uses a single feedback threshold for every user, where the threshold is a function of the average signal-to-noise ratios (SNRs) of the users as well as the number of users involved in the scheduling process. The proposed scheme, however, constructs a sequence of feedback thresholds instead of a single feedback threshold such that each user compares its channel quality with the corresponding feedback threshold in the sequence. Numerical and simulation results show that thanks to the flexibility of threshold selection, where a potentially different threshold can be used for each user, the proposed scheme provides a higher system capacity than that for the conventional scheme. © 2006 IEEE.

  5. Network coding multiuser scheme for indoor visible light communications

    Science.gov (United States)

    Zhang, Jiankun; Dang, Anhong

    2017-12-01

    Visible light communication (VLC) is a unique alternative for indoor data transfer and developing beyond point-to-point. However, for realizing high-capacity networks, VLC is facing challenges including the constrained bandwidth of the optical access point and random occlusion. A network coding scheme for VLC (NC-VLC) is proposed, with increased throughput and system robustness. Based on the Lambertian illumination model, theoretical decoding failure probability of the multiuser NC-VLC system is derived, and the impact of the system parameters on the performance is analyzed. Experiments demonstrate the proposed scheme successfully in the indoor multiuser scenario. These results indicate that the NC-VLC system shows a good performance under the link loss and random occlusion.

  6. Multi-User GeoGebra for Virtual Math Teams

    Directory of Open Access Journals (Sweden)

    Gerry Stahl

    2010-05-01

    Full Text Available The Math Forum is an online resource center for pre-algebra, algebra, geometry and pre-calculus. Its Virtual Math Teams (VMT service provides an integrated web-based environment for small teams to discuss mathematics. The VMT collaboration environment now includes the dynamic mathematics application, GeoGebra. It offers a multi-user version of GeoGebra, which can be used in concert with VMT’s chat, web browsers, curricula and wiki repository.

  7. Multipass Channel Estimation and Joint Multiuser Detection and Equalization for MIMO Long-Code DS/CDMA Systems

    Directory of Open Access Journals (Sweden)

    Buzzi Stefano

    2006-01-01

    Full Text Available The problem of joint channel estimation, equalization, and multiuser detection for a multiantenna DS/CDMA system operating over a frequency-selective fading channel and adopting long aperiodic spreading codes is considered in this paper. First of all, we present several channel estimation and multiuser data detection schemes suited for multiantenna long-code DS/CDMA systems. Then, a multipass strategy, wherein the data detection and the channel estimation procedures exchange information in a recursive fashion, is introduced and analyzed for the proposed scenario. Remarkably, this strategy provides, at the price of some attendant computational complexity increase, excellent performance even when very short training sequences are transmitted, and thus couples together the conflicting advantages of both trained and blind systems, that is, good performance and no wasted bandwidth, respectively. Space-time coded systems are also considered, and it is shown that the multipass strategy provides excellent results for such systems also. Likewise, it is also shown that excellent performance is achieved also when each user adopts the same spreading code for all of its transmit antennas. The validity of the proposed procedure is corroborated by both simulation results and analytical findings. In particular, it is shown that adopting the multipass strategy results in a remarkable reduction of the channel estimation mean-square error and of the optimal length of the training sequence.

  8. Proposal for Implementing Multi-User Database (MUD) Technology in an Academic Library.

    Science.gov (United States)

    Filby, A. M. Iliana

    1996-01-01

    Explores the use of MOO (multi-user object oriented) virtual environments in academic libraries to enhance reference services. Highlights include the development of multi-user database (MUD) technology from gaming to non-recreational settings; programming issues; collaborative MOOs; MOOs as distinguished from other types of virtual reality; audio…

  9. Robust Transceiver Design for Multiuser MIMO Downlink with Channel Uncertainties

    Science.gov (United States)

    Miao, Wei; Li, Yunzhou; Chen, Xiang; Zhou, Shidong; Wang, Jing

    This letter addresses the problem of robust transceiver design for the multiuser multiple-input-multiple-output (MIMO) downlink where the channel state information at the base station (BS) is imperfect. A stochastic approach which minimizes the expectation of the total mean square error (MSE) of the downlink conditioned on the channel estimates under a total transmit power constraint is adopted. The iterative algorithm reported in [2] is improved to handle the proposed robust optimization problem. Simulation results show that our proposed robust scheme effectively reduces the performance loss due to channel uncertainties and outperforms existing methods, especially when the channel errors of the users are different.

  10. Voltage margin control for offshore multi-use platform integration

    DEFF Research Database (Denmark)

    Mier, V.; Casielles, P.G.; Koto, J.

    This paper discusses a multiterminal direct current (MTDC) connection proposed for integration of offshore multi-use platforms into continental grids. Voltage source converters (VSC) were selected for their suitability for multiterminal dc systems and for their flexibility in control. A five...... terminal VSC-MTDC which includes offshore generation, storage, loads and ac connection, was modeled and simulated in DigSILENT Power Factory software. Voltage margin method has been used for reliable operation of the MTDC system without the need of fast communication. Simulation results show......, sell or store energy attending to the price in the electricity market....

  11. Managing a Safe and Successful Multi-User Spaceport

    Science.gov (United States)

    Dacko, Taylor; Ketterer, Kirk; Meade, Phillip

    2016-01-01

    Encouraged by the creation of the Office of Commercial Space Transportation within the U.S. Federal Aviation Administration (FAA) in 1984 and the Commercial Space Act of 1998, the National Aeronautics and Space Administration (NASA) now relies on an extensive network of support from commercial companies and organizations. At NASA's Kennedy Space Center (KSC), this collaboration opens competitive opportunities for launch providers, including repurposing underutilized Shuttle Program resources, constructing new facilities, and utilizing center services and laboratories. The resulting multi-user spaceport fosters diverse activity, though it engenders risk from hazards associated with various spaceflight processing activities. The KSC Safety & Mission Assurance (S&MA) Directorate, in coordination with the center's Spaceport Integration and Center Planning & Development organizations, has developed a novel approach to protect NASA's workforce, critical assets, and the public from hazardous, space-related activity associated with KSC's multi-user spaceport. For NASA KSC S&MA, the transformation to a multi-user spaceport required implementing methods to foster safe and successful commercial activity while resolving challenges involving: Retirement of the Space Shuttle program; Co-location of multiple NASA programs; Relationships between the NASA programs; Complex relationships between NASA programs and commercial partner operations in exclusive-use facilities; Complex relationships between NASA programs and commercial partner operations in shared-use facilities. NASA KSC S&MA challenges were met with long-term planning and solutions involving cooperation with the Spaceport Integration and Services Directorate. This directorate is responsible for managing active commercial partnerships with customer advocacy and services management, providing a dedicated and consistent level of support to a wide array of commercial operations. This paper explores these solutions, their

  12. Multi-user Activity Recognition in a Smart Home

    DEFF Research Database (Denmark)

    Wang, Liang; Gu, Tao; Tao, Xianping

    2010-01-01

    The advances of wearable sensors and wireless networks offer many opportunities to recognize human activities from sensor readings in pervasive computing. Existing work so far focus mainly on recognizing activities of a single user in a home environment. However, there are typically multiple...... inhabitants in a real home and they often perform activities together. In this paper, we investigate the problem of recognizing multi-user activities using wearable sensors in a home setting. We develop a multi-modal, wearable sensor platform to collect sensor data for multiple users, and study two temporal...

  13. CAMAC programming for PDP-11 computers: A modular, multiuser approach

    International Nuclear Information System (INIS)

    Vegh, J.

    1987-01-01

    A user-friendly CAMAC handling software concept for multitask environments is presented. The CAMAC modules are handled like all the other devices, with all the multiuser capabilities of the operating system. The concept is implemented under the RSX-11M operating system and results in effective and modular software. The system serves typically a few thousands of events in a second; the actual speed depends on many factors. In small and medium size systems the concept has several advantages; the test applications are supported mainly on macro (machine code) level and with some limitations on system level. (orig.)

  14. Efficacy of low-calorie, partial meal replacement diet plans on weight and abdominal fat in obese subjects with metabolic syndrome: a double-blind, randomised controlled trial of two diet plans - one high in protein and one nutritionally balanced.

    Science.gov (United States)

    Lee, K; Lee, J; Bae, W K; Choi, J K; Kim, H J; Cho, B

    2009-02-01

    Little is known about the relative efficacy of high-protein vs. conventional diet plans that include partial meal replacements on body fat loss in obese subjects with metabolic syndrome. We aimed to evaluate the efficacy of two low-calorie diets with partial meal replacement plans-a high-protein plan (HP) and a nutritionally balanced conventional (C) plan-on reducing obesity in obese subjects with metabolic syndrome. In a 12-week, double-blind study, we randomised 75 participants to either the HP- or the C-plan group. We recorded key metrics at 0 and 12 weeks. The overall mean weight loss was 5 kg in the HP-plan group and 4.9 kg in the C-plan group (p = 0.72). Truncal fat mass decreased 1.6 kg in the HP-plan group (p or = 70% dietary compliance, however, truncal and whole body fat mass decreased more in the HP-plan group (Delta 2.2 kg and Delta 3.5 kg respectively) than in the C-plan group (Delta 1.3 kg and Delta 2.3 [corrected] kg respectively) (p < 0.05). The HP- and C-plans had a similar effect on weight and abdominal fat reduction, but the HP-plan was more effective in reducing body fat among compliant subjects.

  15. Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial.

    Science.gov (United States)

    Gebauer, Sarah K; Destaillats, Frédéric; Dionisi, Fabiola; Krauss, Ronald M; Baer, David J

    2015-12-01

    Adverse effects of industrially produced trans fatty acids (iTFAs) on the risk of coronary artery disease are well documented in the scientific literature; however, effects of naturally occurring trans fatty acids (TFAs) from ruminant animals (rTFA), such as vaccenic acid (VA) and cis-9,trans-11 conjugated linoleic acid (c9,t11-CLA), are less clear. Although animal and cell studies suggest that VA and c9,t11-CLA may be hypocholesterolemic and antiatherogenic, epidemiologic data comparing rTFAs and iTFAs are inconsistent, and human intervention studies have been limited, underpowered, and not well controlled. We determined the effects of VA, c9,t11-CLA, and iTFA, in the context of highly controlled diets (24 d each), on lipoprotein risk factors compared with a control diet. We conducted a double-blind, randomized, crossover feeding trial in 106 healthy adults [mean ± SD age: 47 ± 10.8 y; body mass index (in kg/m(2)): 28.5 ± 4.0; low-density lipoprotein (LDL) cholesterol: 3.24 ± 0.63 mmol/L]. Diets were designed to have stearic acid replaced with the following TFA isomers (percentage of energy): 0.1% mixed isomers of TFA (control), ∼3% VA, ∼3% iTFA, or 1% c9,t11-CLA. Total dietary fat (34% of energy) and other macronutrients were matched. Total cholesterol (TC), LDL cholesterol, triacylglycerol, lipoprotein(a), and apolipoprotein B were higher after VA than after iTFA; high-density lipoprotein (HDL) cholesterol and apolipoprotein AI also were higher after VA. Compared with control, VA and iTFA both increased TC, LDL cholesterol, ratio of TC to HDL cholesterol, and apolipoprotein B (2-6% change; P cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) (2-6% change; P < 0.05), whereas iTFA did not. c9,t11-CLA lowered triacylglycerol (P ≤ 0.01) and had no effect on other lipoprotein risk factors. With respect to risk of cardiovascular disease, these results are consistent with current nutrition labeling guidelines, with the requirement of VA, but

  16. A Hybrid Approach to Spatial Multiplexing in Multiuser MIMO Downlinks

    Directory of Open Access Journals (Sweden)

    Spencer Quentin H

    2004-01-01

    Full Text Available In the downlink of a multiuser multiple-input multiple-output (MIMO communication system, simultaneous transmission to several users requires joint optimization of the transmitted signals. Allowing all users to have multiple antennas adds an additional degree of complexity to the problem. In this paper, we examine the case where a single base station transmits to multiple users using linear processing (beamforming at each of the antenna arrays. We propose generalizations of several previous iterative algorithms for multiuser transmit beamforming that allow multiple antennas and multiple data streams for each user, and that take into account imperfect channel estimates at the transmitter. We then present a new hybrid algorithm that is based on coordinated transmit-receive beamforming, and combines the strengths of nonorthogonal iterative solutions with zero-forcing solutions. The problem of distributing power among the subchannels is solved by using standard bit-loading algorithms combined with the subchannel gains resulting from the zero-forcing solution. The result is a significant performance improvement over equal power distribution. At the same time, the number of iterations required to compute the final solution is reduced.

  17. Swarm, genetic and evolutionary programming algorithms applied to multiuser detection

    Directory of Open Access Journals (Sweden)

    Paul Jean Etienne Jeszensky

    2005-02-01

    Full Text Available In this paper, the particles swarm optimization technique, recently published in the literature, and applied to Direct Sequence/Code Division Multiple Access systems (DS/CDMA with multiuser detection (MuD is analyzed, evaluated and compared. The Swarm algorithm efficiency when applied to the DS-CDMA multiuser detection (Swarm-MuD is compared through the tradeoff performance versus computational complexity, being the complexity expressed in terms of the number of necessary operations in order to reach the performance obtained through the optimum detector or the Maximum Likelihood detector (ML. The comparison is accomplished among the genetic algorithm, evolutionary programming with cloning and Swarm algorithm under the same simulation basis. Additionally, it is proposed an heuristics-MuD complexity analysis through the number of computational operations. Finally, an analysis is carried out for the input parameters of the Swarm algorithm in the attempt to find the optimum parameters (or almost-optimum for the algorithm applied to the MuD problem.

  18. The ATLAS multi-user upgrade and potential applications

    Energy Technology Data Exchange (ETDEWEB)

    Mustapha, B.; Nolen, J. A.; Savard, G.; Ostroumov, P. N.

    2017-12-01

    With the recent integration of the CARIBU-EBIS charge breeder into the ATLAS accelerator system to provide for more pure and efficient charge breeding of radioactive beams, a multi-user upgrade of the ATLAS facility is being proposed to serve multiple users simultaneously. ATLAS was the first superconducting ion linac in the world and is the US DOE low-energy Nuclear Physics National User Facility. The proposed upgrade will take advantage of the continuous-wave nature of ATLAS and the pulsed nature of the EBIS charge breeder in order to simultaneously accelerate two beams with very close mass-to-charge ratios; one stable from the existing ECR ion source and one radioactive from the newly commissioned EBIS charge breeder. In addition to enhancing the nuclear physics program, beam extraction at different points along the linac will open up the opportunity for other potential applications; for instance, material irradiation studies at ~ 1 MeV/u and isotope production at ~ 6 MeV/u or at the full ATLAS energy of ~ 15 MeV/u. The concept and proposed implementation of the ATLAS multi-user upgrade will be presented. Future plans to enhance the flexibility of this upgrade will also be presented.

  19. Multiuser chirp modulation for underwater acoustic channel based on VTRM

    Directory of Open Access Journals (Sweden)

    Fei Yuan

    2017-05-01

    Full Text Available In this paper, an ascheme is proposed for multiuser underwater acoustic communication by using the multi-chirp rate signals. It differs from the well known TDMA (Time Division Multiple Access, FDMA (Frequency Division Multiple Access or CDMA (Code Division Multiple Access, by assigning each users with different chirp-rate carriers instead of the time, frequency or PN code. Multi-chirp rate signals can be separated from each other by FrFT (Fractional Fourier Transform, which can be regarded as the chirp-based decomposing, and superior to the match filter in the underwater acoustic channel. VTRM (Virtual Time Reverse Mirror is applied into the system to alleviate the ISI caused by the multipatch and make the equalization more simple. Results of computer simulations and pool experiments prove that the proposed multiuser underwater acoustic communication based on the multi-chirp rate exhibit well performance. Outfield experments carrie out in Xiamen Port show that using about 10 kHz bandwidth, four users could communicate at the same time with 425 bps with low BER and can match the UAC application.

  20. On the Delay-Energy Tradeoff in Multiuser Fading Channels

    Directory of Open Access Journals (Sweden)

    Ralf R. Müller

    2009-01-01

    Full Text Available We consider the delay-energy tradeoff on a fading channel with multiuser diversity. For fixed arbitrary rates of the users, the total transmitted energy is minimized subject to a delay constraint. To achieve this goal we propose a scheme which schedules a subset of all users simultaneously. The scheduled users are allocated power to guarantee successful separation at the detector by successive decoding. In this way, we can benefit from both multiuser diversity and the near-far situation via scheduling and simultaneous transmission, respectively. We analytically show that when the number of users goes to infinity the energy required to guarantee the required user rates can be made as small as required at the cost of a higher delay “delay-energy tradeoff”. We explicitly compute the delay under the proposed scheduling policy and discuss how delay differentiation can be achieved. We extend the results to multiband multiaccess channel. Finally, all the results can be generalized in a straightforward fashion to broadcast channel due to the Gaussian multiaccess-broadcast channel duality.

  1. Perbandingan Kinerja Deteksi Multiuser Linier Dan Deteksi Multiuser Dengan Jaringan Syaraf Tiruan Pada Sistem DS-CDMA

    Directory of Open Access Journals (Sweden)

    Popy Maria

    2016-03-01

    Full Text Available Beberapa hal yang dapat menurunkan kapasitas dan kualitas sinyal informasi yang diterima pada sistem DS-CDMA (Direct Sequence Code Division Multiple Access adalah interferensi, noise dan efek near-far. Pada umumnya efek near-far diatasi dengan menggunakan power control. Namun demikian power control tidak dapat mengatasi interferensi yang disebabkan oleh user lain pada kanal yang sama atau yang lebih dikenal dengan MAI (Multiple Access Interference. Pendekatan lain yang digunakan untuk mengatasi hal ini adalah dengan deteksi multiuser (MUD. Pada tugas akhir ini akan dibandingkan kinerja dari MUD linier yang terdiri dari decorrelating dan MMSE dengan MUD yang menggunakan jaringan syaraf tiruan (JST dan mengacu pada deteksi konvensional. Jaringan syaraf tiruan ini menggunakan algoritma propagasi balik. Deteksi multiuser ini diaplikasikan pada  output deteksi konvensional. Kinerja dari masing-masing detektor dilihat dari BER sebagai fungsi nilai SNR  atau jumlah user pada kanal AWGN dan Rayleigh fading. Hasil simulasi pada  kanal AWGN, menunjukkan bahwa MUD dengan JST mempunyai kinerja yang lebih baik. Untuk target BER 10-3 pada kanal  AWGN, MUD decorrelating mencapainya pada SNR 6.3 dB, MUD MMSE pada SNR 5.97 dB, dan MUD dengan JST pada SNR 5.89 dB sedangkan pada kanal Rayleigh, MUD decorrelating mencapainya pada SNR 11.74 dB, MUD MMSE pada SNR 10.91 dB, dan MUD dengan JST pada SNR 10.31 dB

  2. Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

    Science.gov (United States)

    Li, Husheng; Betz, Sharon M.; Poor, H. Vincent

    2007-05-01

    This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.

  3. Center Planning and Development: Multi-User Spaceport Initiatives

    Science.gov (United States)

    Kennedy, Christopher John

    2015-01-01

    The Vehicle Assembly building at NASAs Kennedy Space Center has been used since 1966 to vertically assemble every launch vehicle, since the Apollo Program, launched from Launch Complex 39 (LC-39). After the cancellation of the Constellation Program in 2010 and the retirement of the Space Shuttle Program in 2011, the VAB faced an uncertain future. As the Space Launch System (SLS) gained a foothold as the future of American spaceflight to deep space, NASA was only using a portion of the VABs initial potential. With three high bays connected to the Crawler Way transportation system, the potential exists for up to three rockets to be simultaneously processed for launch. The Kennedy Space Center (KSC) Master plan, supported by the Center Planning and Development (CPD) Directorate, is guiding Kennedy toward a 21st century multi-user spaceport. This concept will maintain Kennedy as the United States premier gateway to space and provide multi-user operations through partnerships with the commercial aerospace industry. Commercial aerospace companies, now tasked with transporting cargo and, in the future, astronauts to the International Space Station (ISS) via the Commercial Resupply Service (CRS) and Commercial Crew Program (CCP), are a rapidly growing industry with increasing capabilities to make launch operations more economical for both private companies and the government. Commercial operations to Low Earth Orbit allow the government to focus on travel to farther destinations through the SLS Program. With LC-39B designated as a multi-use launch pad, companies seeking to use it will require an integration facility to assemble, integrate, and test their launch vehicle. An Announcement for Proposals (AFP) was released in June, beginning the process of finding a non-NASA user for High Bay 2 (HB2) and the Mobile Launcher Platforms (MLPs). An Industry Day, a business meeting and tour for interested companies and organizations, was also arranged to identify and answer any

  4. A Low-Complexity Blind Multiuser Receiver for Long-Code CDMA

    NARCIS (Netherlands)

    Dang, Q.H.; Van Der Veen, A.J.

    2004-01-01

    Receivers for long-code systems are for computational reasons usually based on simple matched-filter techniques, and hence suffer from multiaccess interference. Decorrelating RAKE and MMSE receivers do not have this problem but have not been widely studied due to the apparent complexity of the

  5. Exploiting Multi-user Diversity and Multi-hop Diversity in Dual-hop Broadcast Channels

    KAUST Repository

    Zafar, Ammar

    2013-05-21

    We propose joint user-and-hop scheduling over dual-hop block-fading broadcast channels in order to exploit multi-user diversity gains and multi-hop diversity gains all together. To achieve this objective, the first and second hops are scheduled opportunistically based on the channel state information. The joint scheduling problem is formulated as maximizing the weighted sum of the long term achievable rates of the users under a stability constraint, which means that in the long term the rate received by the relay should equal the rate transmitted by it, in addition to power constraints. We show that this problem is equivalent to a single-hop broadcast channel by treating the source as a virtual user with an optimal weight that maintains the stability constraint. We show how to obtain the source weight either off-line based on channel statistics or on real-time based on channel measurements. Furthermore, we consider special cases including the maximum sum-rate scheduler and the proportional fair scheduler. We also show how to extend the scheme into one that allows multiple user scheduling via superposition coding with successive decoding. Numerical results demonstrate that our proposed joint scheduling scheme enlarges the rate region as compared to scheduling schemes that exploit the diversity gains partially.

  6. Polyimide and Metals MEMS Multi-User Processes

    KAUST Repository

    Arevalo, Arpys

    2016-11-01

    The development of a polyimide and metals multi-user surface micro-machining process for Micro-electro-mechanical Systems (MEMS) is presented. The process was designed to be as general as possible, and designed to be capable to fabricate different designs on a single silicon wafer. The process was not optimized with the purpose of fabricating any one specific device but can be tweaked to satisfy individual needs depending on the application. The fabrication process uses Polyimide as the structural material and three separated metallization layers that can be interconnected depending on the desired application. The technology allows the development of out-of-plane compliant mechanisms, which can be combined with six variations of different physical principles for actuation and sensing on a single processed silicon wafer. These variations are: electrostatic motion, thermal bimorph actuation, capacitive sensing, magnetic sensing, thermocouple-based sensing and radio frequency transmission and reception.

  7. Optimal and Fair Resource Allocation for Multiuser Wireless Multimedia Transmissions

    Directory of Open Access Journals (Sweden)

    Zhangyu Guan

    2009-01-01

    Full Text Available This paper presents an optimal and fair strategy for multiuser multimedia radio resource allocation (RRA based on coopetition, which suggests a judicious mixture of competition and cooperation. We formulate the co-opetition strategy as sum utility maximization at constraints from both Physical (PHY and Application (APP layers. We show that the maximization can be solved efficiently employing the well-defined Layering as Optimization Decomposition (LOD method. Moreover, the coopetition strategy is applied to power allocation among multiple video users, and evaluated through comparing with existing- competition based strategy. Numerical results indicate that, the co-opetition strategy adapts the best to the changes of network conditions, participating users, and so forth. It is also shown that the coopetition can lead to an improved number of satisfied users, and in the meanwhile provide more flexible tradeoff between system efficiency and fairness among users.

  8. Multiuser detection and channel estimation: Exact and approximate methods

    DEFF Research Database (Denmark)

    Fabricius, Thomas

    2003-01-01

    subtractive interference cancellation with hyperbolic tangent tentative decision device, in statistical mechanics and machine learning called the naive mean field approach. The differences between the proposed algorithms lie in how the bias is estimated/approximated. We propose approaches based on a second...... propose here to use accurate approximations borrowed from statistical mechanics and machine learning. These give us various algorithms that all can be formulated in a subtractive interference cancellation formalism. The suggested algorithms can e ectively be seen as bias corrections to standard...... of the Junction Tree Algorithm, which is a generalisation of Pearl's Belief Propagation, the BCJR, sum product, min/max sum, and Viterbi's algorithm. Although efficient algoithms, they have an inherent exponential complexity in the number of users when applied to CDMA multiuser detection. For this reason we...

  9. On multiuser switched diversity transmission for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2012-01-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users share the spectrum with primary users. In particular, we devise two schemes for selecting the user among those that satisfy the interference constraints and achieve an acceptable signal-to-noise ratio (SNR) level. The first scheme selects the user with the maximum SNR at the receiver, whereas in the second scheme the users are scanned in a sequential manner until an acceptable user is found. In addition, we consider two power adaptive settings. In the on/off power adaptive setting, the users transmit based on whether the interference constraint is met or not while in the full power adaptive setting, the users vary their transmission power to satisfy the interference constraint. Finally, we present numerical results of our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load of both schemes. © 2012 ICST.

  10. Authenticated multi-user quantum key distribution with single particles

    Science.gov (United States)

    Lin, Song; Wang, Hui; Guo, Gong-De; Ye, Guo-Hua; Du, Hong-Zhen; Liu, Xiao-Fen

    2016-03-01

    Quantum key distribution (QKD) has been growing rapidly in recent years and becomes one of the hottest issues in quantum information science. During the implementation of QKD on a network, identity authentication has been one main problem. In this paper, an efficient authenticated multi-user quantum key distribution (MQKD) protocol with single particles is proposed. In this protocol, any two users on a quantum network can perform mutual authentication and share a secure session key with the assistance of a semi-honest center. Meanwhile, the particles, which are used as quantum information carriers, are not required to be stored, therefore the proposed protocol is feasible with current technology. Finally, security analysis shows that this protocol is secure in theory.

  11. Multilevel and multi-user sustainability assessment of farming systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Passel, Steven, E-mail: Steven.vanpassel@uhasselt.be [Hasselt University, Faculty of Business Economics, Centre for Environmental Sciences, Agoralaan, Building D, 3590, Diepenbeek (Belgium); University of Antwerp, Department Bioscience Engineering, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Meul, Marijke [University College Ghent, Department of Biosciences and Landscape Architecture, Campus Schoonmeersen, Building C, Schoonmeersstraat 52, 9000, Gent (Belgium)

    2012-01-15

    Sustainability assessment is needed to build sustainable farming systems. A broad range of sustainability concepts, methodologies and applications already exists. They differ in level, focus, orientation, measurement, scale, presentation and intended end-users. In this paper we illustrate that a smart combination of existing methods with different levels of application can make sustainability assessment more profound, and that it can broaden the insights of different end-user groups. An overview of sustainability assessment tools on different levels and for different end-users shows the complementarities and the opportunities of using different methods. In a case-study, a combination of the sustainable value approach (SVA) and MOTIFS is used to perform a sustainability evaluation of farming systems in Flanders. SVA is used to evaluate sustainability at sector level, and is especially useful to support policy makers, while MOTIFS is used to support and guide farmers towards sustainability at farm level. The combined use of the two methods with complementary goals can widen the insights of both farmers and policy makers, without losing the particularities of the different approaches. To stimulate and support further research and applications, we propose guidelines for multilevel and multi-user sustainability assessments. - Highlights: Black-Right-Pointing-Pointer We give an overview of sustainability assessment tools for agricultural systems. Black-Right-Pointing-Pointer SVA and MOTIFS are used to evaluate the sustainability of dairy farming in Flanders. Black-Right-Pointing-Pointer Combination of methods with different levels broadens the insights of different end-user groups. Black-Right-Pointing-Pointer We propose guidelines for multilevel and multi-user sustainability assessments.

  12. Multilevel and multi-user sustainability assessment of farming systems

    International Nuclear Information System (INIS)

    Van Passel, Steven; Meul, Marijke

    2012-01-01

    Sustainability assessment is needed to build sustainable farming systems. A broad range of sustainability concepts, methodologies and applications already exists. They differ in level, focus, orientation, measurement, scale, presentation and intended end-users. In this paper we illustrate that a smart combination of existing methods with different levels of application can make sustainability assessment more profound, and that it can broaden the insights of different end-user groups. An overview of sustainability assessment tools on different levels and for different end-users shows the complementarities and the opportunities of using different methods. In a case-study, a combination of the sustainable value approach (SVA) and MOTIFS is used to perform a sustainability evaluation of farming systems in Flanders. SVA is used to evaluate sustainability at sector level, and is especially useful to support policy makers, while MOTIFS is used to support and guide farmers towards sustainability at farm level. The combined use of the two methods with complementary goals can widen the insights of both farmers and policy makers, without losing the particularities of the different approaches. To stimulate and support further research and applications, we propose guidelines for multilevel and multi-user sustainability assessments. - Highlights: ► We give an overview of sustainability assessment tools for agricultural systems. ► SVA and MOTIFS are used to evaluate the sustainability of dairy farming in Flanders. ► Combination of methods with different levels broadens the insights of different end-user groups. ► We propose guidelines for multilevel and multi-user sustainability assessments.

  13. What is Color Blindness?

    Science.gov (United States)

    ... Color Blindness? Who Is at Risk for Color Blindness? Color Blindness Causes Color Blindness Diagnosis and Treatment How Color Blindness Is Tested What Is Color Blindness? Leer en Español: ¿Qué es el daltonismo? Written ...

  14. On the Feedback Reduction of Relay Multiuser Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil; Eltayeb, Mohammed; Kammoun, Abla; Al-Naffouri, Tareq Y.; Bahrami, Hamid Reza

    2016-01-01

    This paper presents a comprehensive performance analysis of full-duplex multiuser relay networks employing opportunistic scheduling with noisy and compressive feedback. Specifically, two feedback techniques based on compressive sensing (CS) theory

  15. Multi-Use Non-Intrusive Flow Characterization System (FCS), Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation is a Multi-Use Non-Intrusive Flow Characterization System (FCS) for densified, normal boiling point, and two-phase cryogenic flows, capable of...

  16. On the performance of free-space optical communication systems with multiuser diversity

    KAUST Repository

    Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

    2014-01-01

    Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD

  17. Muddy Learning: Evaluating Learning in Multi-User Computer-Based Environments

    National Research Council Canada - National Science Library

    McArthur, David

    1998-01-01

    ... (Multiple User Synthetic Environments), and MOOs (Multi-User Object Oriented), enables users to create new "rooms" in virtual worlds, define their own personnaes, and engage visitors in rich dialogues...

  18. Multiuser Diversity with Adaptive Modulation in Non-Identically Distributed Nakagami Fading Environments

    KAUST Repository

    Rao, Anlei; Alouini, Mohamed-Slim

    2012-01-01

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel

  19. SWIPT in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma; Salem, Ahmed Sultan; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, we consider a multiuser multiple- input multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting relays and multiple destinations. Since the end-to-end sum rate

  20. Feedback Reduction in Broadcast and two Hop Multiuser Networks: A Compressed Sensing Approach

    KAUST Repository

    Shibli, Hussain J.

    2013-01-01

    In multiuser wireless networks, the base stations (BSs) rely on the channel state information (CSI) of the users to in order to perform user scheduling and downlink transmission. While the downlink channels can be easily estimated at all user

  1. STAGING THROUGH PROTOTYPING WITH PARTIALLY BLINDED PEOPLE

    DEFF Research Database (Denmark)

    Brodersen, Søsser; Lindegaard, Hanne

    2017-01-01

    self-sufficient. Studies show that visual impaired persons rarely are involved in designing such technologies, which in many cases causes them to be excluded from everyday activities. We discuss how a design team applied collaborative methods and prototypes as boundary objects in dialogue with visually...... impaired people aiming including them as user of a self-service technology. The use of material objects from the very start of the design process contributed to a process in which the designers and visually impaired persons co-designed a new user interface that would enable these actors to collect and send...... parcels through ‘døgnbox’, an self-service, touchscreen-based postal system in Denmark (Nielsen et al. 2015). We describe how the design team used a variety of material objects to interest, enrol and mobilise the visually impaired actors in design processes (Callon 1986). We also discuss how...

  2. Perception of blindness and blinding eye conditions in rural communities.

    Science.gov (United States)

    Ashaye, Adeyinka; Ajuwon, Ademola Johnson; Adeoti, Caroline

    2006-01-01

    PURPOSE: The purpose of this qualitative study was to explore the causes and management of blindness and blinding eye conditions as perceived by rural dwellers of two Yoruba communities in Oyo State, Nigeria. METHODS: Four focus group discussions were conducted among residents of Iddo and Isale Oyo, two rural Yoruba communities in Oyo State, Nigeria. Participants consisted of sighted, those who were partially or totally blind and community leaders. Ten patent medicine sellers and 12 traditional healers were also interviewed on their perception of the causes and management of blindness in their communities. FINDINGS: Blindness was perceived as an increasing problem among the communities. Multiple factors were perceived to cause blindness, including germs, onchocerciasis and supernatural forces. Traditional healers believed that blindness could be cured, with many claiming that they had previously cured blindness in the past. However, all agreed that patience was an important requirement for the cure of blindness. The patent medicine sellers' reports were similar to those of the traditional healers. The barriers to use of orthodox medicine were mainly fear, misconception and perceived high costs of care. There was a consensus of opinion among group discussants and informants that there are severe social and economic consequences of blindness, including not been able to see and assess the quality of what the sufferer eats, perpetual sadness, loss of sleep and dependence on other persons for daily activities. CONCLUSION: Local beliefs associated with causation, symptoms and management of blindness and blinding eye conditions among rural Yoruba communities identified have provided a bridge for understanding local perspectives and basis for implementing appropriate primary eye care programs. PMID:16775910

  3. Multi-user distribution of polarization entangled photon pairs

    Energy Technology Data Exchange (ETDEWEB)

    Trapateau, J.; Orieux, A.; Diamanti, E.; Zaquine, I., E-mail: isabelle.zaquine@telecom-paristech.fr [LTCI, CNRS, Télécom ParisTech, Université Paris-Saclay, 75013 Paris (France); Ghalbouni, J. [Applied Physics Laboratory, Faculty of Sciences 2, Lebanese University, Campus Fanar, BP 90656 Jdeidet (Lebanon)

    2015-10-14

    We experimentally demonstrate multi-user distribution of polarization entanglement using commercial telecom wavelength division demultiplexers. The entangled photon pairs are generated from a broadband source based on spontaneous parametric down conversion in a periodically poled lithium niobate crystal using a double path setup employing a Michelson interferometer and active phase stabilisation. We test and compare demultiplexers based on various technologies and analyze the effect of their characteristics, such as losses and polarization dependence, on the quality of the distributed entanglement for three channel pairs of each demultiplexer. In all cases, we obtain a Bell inequality violation, whose value depends on the demultiplexer features. This demonstrates that entanglement can be distributed to at least three user pairs of a network from a single source. Additionally, we verify for the best demultiplexer that the violation is maintained when the pairs are distributed over a total channel attenuation corresponding to 20 km of optical fiber. These techniques are therefore suitable for resource-efficient practical implementations of entanglement-based quantum key distribution and other quantum communication network applications.

  4. Participatory Design of Multi-Use Platforms at Sea

    Directory of Open Access Journals (Sweden)

    Sander van den Burg

    2016-01-01

    Full Text Available European oceans are subject to rapid development. New activities such as aquaculture and ocean energy have gained importance. This triggers interest in “multi-use platforms at sea” (MUPS, i.e., areas at sea in which different activities are combined. MUPS are complex features with regards to technology, governance, and financial, socioeconomic, and environmental aspects. To identify realistic and sustainable solutions and designs for MUPS, the MERMAID project applied a participatory design process (PDP involving a range of stakeholders representing companies, authorities, researchers, and NGOs. This paper evaluates if and how the participatory design process contributed to the design of multi-use platforms. It is based on interviews with the managers of the case study sites and a questionnaire administered to all stakeholders participating in the PDP workshops. Analyzing the four case studies, we conclude that the participatory design process has had a valuable contribution to the development of the four different designs of MUPS, even though the preconditions for carrying out a participatory design process differed between sites. In all four cases, the process has been beneficial in generating new and shared knowledge. It brought new design issues to the table and increased knowledge and understanding among the different stakeholders.

  5. How supportive are existing national legal regimes for multi-use marine spatial planning?—The South African case

    CSIR Research Space (South Africa)

    Taljaard, Susan

    2013-03-01

    Full Text Available responsible for the environment is viewed as the most appropriate agency to house the statutory mechanism for multi-use MSP at national and provincial levels, but delegating local multi-use MSP processes to local government agencies. The political...

  6. Compressive Sensing for Feedback Reduction in Wireless Multiuser Networks

    KAUST Repository

    Elkhalil, Khalil

    2015-05-01

    User/relay selection is a simple technique that achieves spatial diversity in multiuser networks. However, for user/relay selection algorithms to make a selection decision, channel state information (CSI) from all cooperating users/relays is usually required at a central node. This requirement poses two important challenges. Firstly, CSI acquisition generates a great deal of feedback overhead (air-time) that could result in significant transmission delays. Secondly, the fed-back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. Motivated by the aforementioned challenges, we propose a limited feedback user/relay selection scheme that is based on the theory of compressed sensing. Firstly, we introduce a limited feedback relay selection algorithm for a multicast relay network. The proposed algorithm exploits the theory of compressive sensing to first obtain the identity of the “strong” relays with limited feedback air-time. Following that, the CSI of the selected relays is estimated using minimum mean square error estimation without any additional feedback. To minimize the effect of noise on the fed-back CSI, we introduce a back-off strategy that optimally backs-off on the noisy received CSI. In the second part of the thesis, we propose a feedback reduction scheme for full-duplex relay-aided multiuser networks. The proposed scheme permits the base station (BS) to obtain channel state information (CSI) from a subset of strong users under substantially reduced feedback overhead. More specifically, we cast the problem of user identification and CSI estimation as a block sparse signal recovery problem in compressive sensing (CS). Using existing CS block recovery algorithms, we first obtain the identity of the strong users and then estimate their CSI using the best linear unbiased estimator (BLUE). Moreover, we derive the

  7. Multiuser switched scheduling systems with per-user threshold and post-user selection

    KAUST Repository

    Nam, Haewoon

    2010-06-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed in this paper. Unlike the conventional multiuser switched diversity scheduling scheme where a single threshold is used by all the users in order to determine whether to transmit a feedback, the proposed scheme deploys per-user threshold, where each user uses a potentially different threshold than other users thresholds. This paper first provides a generic analytical framework for the optimal feedback thresholds in a closed form. Then we investigates the impact of user sequence strategies and post selection strategies on the performance of the multiuser switched scheduling scheme with per-user threshold. Numerical and simulation results show that the proposed scheme provides a higher system capacity compared to the conventional scheme. © 2010 IEEE.

  8. Multiuser switched scheduling systems with per-user threshold and post-user selection

    KAUST Repository

    Nam, Haewoon; Alouini, Mohamed-Slim

    2010-01-01

    A multiuser switched diversity scheduling scheme with per-user feedback threshold is proposed in this paper. Unlike the conventional multiuser switched diversity scheduling scheme where a single threshold is used by all the users in order to determine whether to transmit a feedback, the proposed scheme deploys per-user threshold, where each user uses a potentially different threshold than other users thresholds. This paper first provides a generic analytical framework for the optimal feedback thresholds in a closed form. Then we investigates the impact of user sequence strategies and post selection strategies on the performance of the multiuser switched scheduling scheme with per-user threshold. Numerical and simulation results show that the proposed scheme provides a higher system capacity compared to the conventional scheme. © 2010 IEEE.

  9. An Efficient Downlink Scheduling Strategy Using Normal Graphs for Multiuser MIMO Wireless Systems

    Science.gov (United States)

    Chen, Jung-Chieh; Wu, Cheng-Hsuan; Lee, Yao-Nan; Wen, Chao-Kai

    Inspired by the success of the low-density parity-check (LDPC) codes in the field of error-control coding, in this paper we propose transforming the downlink multiuser multiple-input multiple-output scheduling problem into an LDPC-like problem using the normal graph. Based on the normal graph framework, soft information, which indicates the probability that each user will be scheduled to transmit packets at the access point through a specified angle-frequency sub-channel, is exchanged among the local processors to iteratively optimize the multiuser transmission schedule. Computer simulations show that the proposed algorithm can efficiently schedule simultaneous multiuser transmission which then increases the overall channel utilization and reduces the average packet delay.

  10. Blind Cat

    Directory of Open Access Journals (Sweden)

    Arka Chattopadhyay

    2015-08-01

    There’s no way to know whether he was blind from birth or blindness was something he had picked up from his fights with other cats. He wasn’t an urban cat. He lived in a little village, soaked in the smell of fish with a river running right beside it. Cats like these have stories of a different kind. The two-storied hotel where he lived had a wooden floor. It stood right on the riverbank and had more than a tilt towards the river, as if deliberately leaning on the water.

  11. Multi-user cognitive radio network resource allocation based on the adaptive niche immune genetic algorithm

    International Nuclear Information System (INIS)

    Zu Yun-Xiao; Zhou Jie

    2012-01-01

    Multi-user cognitive radio network resource allocation based on the adaptive niche immune genetic algorithm is proposed, and a fitness function is provided. Simulations are conducted using the adaptive niche immune genetic algorithm, the simulated annealing algorithm, the quantum genetic algorithm and the simple genetic algorithm, respectively. The results show that the adaptive niche immune genetic algorithm performs better than the other three algorithms in terms of the multi-user cognitive radio network resource allocation, and has quick convergence speed and strong global searching capability, which effectively reduces the system power consumption and bit error rate. (geophysics, astronomy, and astrophysics)

  12. Genetic Local Search for Optimum Multiuser Detection Problem in DS-CDMA Systems

    Science.gov (United States)

    Wang, Shaowei; Ji, Xiaoyong

    Optimum multiuser detection (OMD) in direct-sequence code-division multiple access (DS-CDMA) systems is an NP-complete problem. In this paper, we present a genetic local search algorithm, which consists of an evolution strategy framework and a local improvement procedure. The evolution strategy searches the space of feasible, locally optimal solutions only. A fast iterated local search algorithm, which employs the proprietary characteristics of the OMD problem, produces local optima with great efficiency. Computer simulations show the bit error rate (BER) performance of the GLS outperforms other multiuser detectors in all cases discussed. The computation time is polynomial complexity in the number of users.

  13. A versatile multi-user polyimide surface micromachinning process for MEMS applications

    KAUST Repository

    Carreno, Armando Arpys Arevalo

    2015-04-01

    This paper reports a versatile multi-user micro-fabrication process for MEMS devices, the \\'Polyimide MEMS Multi-User Process\\' (PiMMPs). The reported process uses polyimide as the structural material and three separate metallization layers that can be interconnected depending on the desired application. This process enables for the first time the development of out-of-plane compliant mechanisms that can be designed using six different physical principles for actuation and sensing on a wafer from a single fabrication run. These principles are electrostatic motion, thermal bimorph actuation, capacitive sensing, magnetic sensing, thermocouple-based sensing and radio frequency transmission and reception. © 2015 IEEE.

  14. Sensor-Based Human Activity Recognition in a Multi-user Scenario

    Science.gov (United States)

    Wang, Liang; Gu, Tao; Tao, Xianping; Lu, Jian

    Existing work on sensor-based activity recognition focuses mainly on single-user activities. However, in real life, activities are often performed by multiple users involving interactions between them. In this paper, we propose Coupled Hidden Markov Models (CHMMs) to recognize multi-user activities from sensor readings in a smart home environment. We develop a multimodal sensing platform and present a theoretical framework to recognize both single-user and multi-user activities. We conduct our trace collection done in a smart home, and evaluate our framework through experimental studies. Our experimental result shows that we achieve an average accuracy of 85.46% with CHMMs.

  15. Outage and ser performance of an opportunistic multi-user underlay cognitive network

    KAUST Repository

    Khan, Fahd Ahmed

    2012-10-01

    Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network and a single secondary user is selected for transmission. The channel is assumed to have independent but not identical Nakagami-m fading. Closed form expressions for the outage performance and the symbol-error-rate performance of the opportunistic multi-user secondary network are derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each secondary user. © 2012 IEEE.

  16. On end-to-end performance of MIMO multiuser in cognitive radio networks

    KAUST Repository

    Yang, Yuli

    2011-12-01

    In this paper, a design for the multiple-input-multiple-output (MIMO) multiuser transmission in the cognitive radio network is developed and its end-to-end performance is investigated under spectrum-sharing constraints. Firstly, the overall average packet error rate is analyzed by considering the channel state information feedback delay and the multiuser scheduling. Then, we provide corresponding numerical results to measure the performance evaluation for several separate scenarios, which presents a convenient tool for the cognitive radio network design with multiple secondary MIMO users. © 2011 IEEE.

  17. Impact of interference on the performance of selection based parallel multiuser scheduling

    KAUST Repository

    Nam, Sungsik

    2012-02-01

    In conventional multiuser parallel scheduling schemes, every scheduled user is interfering with every other scheduled user, which limits the capacity and performance of multiuser systems, and the level of interference becomes substantial as the number of scheduled users increases. Based on the above observations, we investigate the trade-off between the system throughput and the number of scheduled users through the exact analysis of the total average sum rate capacity and the average spectral efficiency. Our analytical results can help the system designer to carefully select the appropriate number of scheduled users to maximize the overall throughput while maintaining an acceptable quality of service under certain channel conditions. © 2012 IEEE.

  18. Design of Simplified Maximum-Likelihood Receivers for Multiuser CPM Systems

    Directory of Open Access Journals (Sweden)

    Li Bing

    2014-01-01

    Full Text Available A class of simplified maximum-likelihood receivers designed for continuous phase modulation based multiuser systems is proposed. The presented receiver is built upon a front end employing mismatched filters and a maximum-likelihood detector defined in a low-dimensional signal space. The performance of the proposed receivers is analyzed and compared to some existing receivers. Some schemes are designed to implement the proposed receivers and to reveal the roles of different system parameters. Analysis and numerical results show that the proposed receivers can approach the optimum multiuser receivers with significantly (even exponentially in some cases reduced complexity and marginal performance degradation.

  19. Design of simplified maximum-likelihood receivers for multiuser CPM systems.

    Science.gov (United States)

    Bing, Li; Bai, Baoming

    2014-01-01

    A class of simplified maximum-likelihood receivers designed for continuous phase modulation based multiuser systems is proposed. The presented receiver is built upon a front end employing mismatched filters and a maximum-likelihood detector defined in a low-dimensional signal space. The performance of the proposed receivers is analyzed and compared to some existing receivers. Some schemes are designed to implement the proposed receivers and to reveal the roles of different system parameters. Analysis and numerical results show that the proposed receivers can approach the optimum multiuser receivers with significantly (even exponentially in some cases) reduced complexity and marginal performance degradation.

  20. On end-to-end performance of MIMO multiuser in cognitive radio networks

    KAUST Repository

    Yang, Yuli; Aissa, Sonia

    2011-01-01

    In this paper, a design for the multiple-input-multiple-output (MIMO) multiuser transmission in the cognitive radio network is developed and its end-to-end performance is investigated under spectrum-sharing constraints. Firstly, the overall average packet error rate is analyzed by considering the channel state information feedback delay and the multiuser scheduling. Then, we provide corresponding numerical results to measure the performance evaluation for several separate scenarios, which presents a convenient tool for the cognitive radio network design with multiple secondary MIMO users. © 2011 IEEE.

  1. Blind Ambition

    Science.gov (United States)

    Olson, Catherine Applefeld

    2009-01-01

    No matter how dedicated they may be, some teachers are daunted by extreme challenges. Carol Agler, music director at the Ohio State School for the Blind (OSSB), is not one of those teachers. Since joining the OSSB staff 11 years ago, Agler has revived the school's long-dormant band program and created its first marching band. Next January, she…

  2. Multi-User Space Link Extension (SLE) System

    Science.gov (United States)

    Perkins, Toby

    2013-01-01

    The Multi-User Space (MUS) Link Extension system, a software and data system, provides Space Link Extension (SLE) users with three space data transfer services in timely, complete, and offline modes as applicable according to standards defined by the Consultative Committee for Space Data Systems (CCSDS). MUS radically reduces the schedule, cost, and risk of implementing a new SLE user system, minimizes operating costs with a lights-out approach to SLE, and is designed to require no sustaining engineering expense during its lifetime unless changes in the CCSDS SLE standards, combined with new provider implementations, force changes. No software modification to MUS needs to be made to support a new mission. Any systems engineer with Linux experience can begin testing SLE user service instances with MUS starting from a personal computer (PC) within five days. For flight operators, MUS provides a familiar-looking Web page for entering SLE configuration data received from SLE. Operators can also use the Web page to back up a space mission's entire set of up to approximately 500 SLE service instances in less than five seconds, or to restore or transfer from another system the same amount of data from a MUS backup file in about the same amount of time. Missions operate each MUS SLE service instance independently by sending it MUS directives, which are legible, plain ASCII strings. MUS directives are usually (but not necessarily) sent through a TCP-IP (Transmission Control Protocol Internet Protocol) socket from a MOC (Mission Operations Center) or POCC (Payload Operations Control Center) system, under scripted control, during "lights-out" spacecraft operation. MUS permits the flight operations team to configure independently each of its data interfaces; not only commands and telemetry, but also MUS status messages to the MOC. Interfaces can use single- or multiple-client TCP/IP server sockets, TCP/IP client sockets, temporary disk files, the system log, or standard in

  3. Acute Blindness.

    Science.gov (United States)

    Meekins, Jessica M

    2015-09-01

    Sudden loss of vision is an ophthalmic emergency with numerous possible causes. Abnormalities may occur at any point within the complex vision pathway, from retina to optic nerve to the visual center in the occipital lobe. This article reviews specific prechiasm (retina and optic nerve) and cerebral cortical diseases that lead to acute blindness. Information regarding specific etiologies, pathophysiology, diagnosis, treatment, and prognosis for vision is discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. A Tabletop Board Game Interface for Multi-User Interaction with a Storytelling System

    NARCIS (Netherlands)

    Alofs, T.; Theune, Mariet; Swartjes, I.M.T.; Camurri, A.; Costa, C.

    2011-01-01

    The Interactive Storyteller is an interactive storytelling system with a multi-user tabletop interface. Our goal was to design a generic framework combining emergent narrative, where stories emerge from the actions of autonomous intelligent agents, with the social aspects of traditional board games.

  5. A Multi-User Virtual Environment for Building and Assessing Higher Order Inquiry Skills in Science

    Science.gov (United States)

    Ketelhut, Diane Jass; Nelson, Brian C.; Clarke, Jody; Dede, Chris

    2010-01-01

    This study investigated novel pedagogies for helping teachers infuse inquiry into a standards-based science curriculum. Using a multi-user virtual environment (MUVE) as a pedagogical vehicle, teams of middle-school students collaboratively solved problems around disease in a virtual town called River City. The students interacted with "avatars" of…

  6. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    KAUST Repository

    Yang, Liang; Gao, Xiqi; Alouini, Mohamed-Slim

    2014-01-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD

  7. CGLXTouch: A multi-user multi-touch approach for ultra-high-resolution collaborative workspaces

    KAUST Repository

    Ponto, Kevin; Doerr, Kai; Wypych, Tom; Kooker, John; Kuester, Falko

    2011-01-01

    multi-touch tablet and phone devices, which can be added to and removed from the system on the fly. Events from these devices are tagged with a device identifier and are synchronized with the distributed display environment, enabling multi-user support

  8. A perspective on multi-user interaction design based on an understanding of domestic lighting conflict

    NARCIS (Netherlands)

    Niemantsverdriet, K.; van Essen, H.A.; Eggen, J.H.

    2017-01-01

    More and more connected systems are entering the social and shared home environment. Interaction with these systems is often rather individual and based on personal preferences, leading to conflicts in multi-user situations. In this paper, we aim to develop a perspective on how to design for

  9. Multiuser TOA Estimation Algorithm in DS-CDMA Sparse Channel for Radiolocation

    Science.gov (United States)

    Kim, Sunwoo

    This letter considers multiuser time delay estimation in a sparse channel environment for radiolocation. The generalized successive interference cancellation (GSIC) algorithm is used to eliminate the multiple access interference (MAI). To adapt GSIC to sparse channels the alternating maximization (AM) algorithm is considered, and the continuous time delay of each path is estimated without requiring a priori known data sequences.

  10. Methodology and Implementation on DSP of Heuristic Multiuser DS/CDMA Detectors

    Directory of Open Access Journals (Sweden)

    Alex Miyamoto Mussi

    2010-12-01

    Full Text Available The growing number of users of mobile communications networks and the scarcity of the electromagnetic spectrum make the use of diversity techniques and detection/decoding efficient, such as the use of multiple antennas at the transmitter and/or receiver, multiuser detection (MuD – Multiuser Detection, among others, have an increasingly prominent role in the telecommunications landscape. This paper presents a design methodology based on digital signal processors (DSP – Digital Signal Processor with a view to the implementation of multiuser heuristics detectors in systems DS/CDMA (Direct Sequence Code Division Multiple Access. Heuristics detection techniques result in near-optimal performance in order to approach the performance of maximum-likelihood (ML. In this work, was employed the DSP development platform called the C6713 DSK, which is based in Texas TMS320C6713 processor. The heuristics techniques proposed are based on well established algorithms in the literature. The efficiency of the algorithms implemented in DSP has been evaluated numerically by computing the measure of bit error rate (BER. Finally, the feasibility of implementation in DSP could then be verified by comparing results from multiple Monte-Carlo simulation in Matlab, with those obtained from implementation on DSP. It also demonstrates the effective increase in performance and system capacity of DS/CDMA with the use of heuristic multiuser detection techniques, implemented directly in the DSP.

  11. Optimal One Bit Time Reversal For UWB Impulse Radio In Multi-User Wireless Communications

    DEFF Research Database (Denmark)

    Nguyen, Hung Tuan

    2008-01-01

    In this paper, with the purpose of further reducing the complexity of the system, while keeping its temporal and spatial focusing performance, we investigate the possibility of using optimal one bit time reversal (TR) system for impulse radio ultra wideband multi-user wireless communications...

  12. Multi-User Domain Object Oriented (MOO) as a High School Procedure for Foreign Language Acquisition.

    Science.gov (United States)

    Backer, James A.

    Foreign language students experience added difficulty when they are isolated from native speakers and from the culture of the target language. It has been posited that MOO (Multi-User Domain Object Oriented) may help overcome the geographical isolation of these students. MOOs are Internet-based virtual worlds in which people from all over the real…

  13. Sensor-based Human Activity Recognition in a Multi-user Scenario

    DEFF Research Database (Denmark)

    Wang, Liang; Gu, Tao; Tao, Xianping

    2009-01-01

    Existing work on sensor-based activity recognition focuses mainly on single-user activities. However, in real life, activities are often performed by multiple users involving interactions between them. In this paper, we propose Coupled Hidden Markov Models (CHMMs) to recognize multi-user activiti...

  14. Two-Way Multiuser Mixed RF/FSO Relaying: Performance Analysis and Power Allocation

    KAUST Repository

    Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim

    2018-01-01

    In this paper, the performance of two-way multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. RF links are used to conduct data transmission between

  15. Iterative MIMO Turbo Multiuser Detection and Equalization for STTrC-Coded Systems with Unknown Interference

    Directory of Open Access Journals (Sweden)

    Veselinovic Nenad

    2004-01-01

    Full Text Available Iterative multiuser detection in a single-carrier broadband multiple-input multiple-output (MIMO system is studied in this paper. A minimum mean squared error (MMSE low-complexity multiuser receiver is derived for space-division multiple-access (SDMA space-time trellis-coded (STTrC systems in frequency-selective fading channels. The receiver uses MMSE filtering to jointly detect several transmit antennas of the user of interest, while the interference from the undetected transmit antennas, cochannel interference (CCI, and intersymbol interference (ISI are all cancelled by the soft cancellation. The performances of two extreme receiver cases are evaluated. In the first case, only one transmit antenna of the user of interest is detected at a time and the remaining ones are cancelled by soft cancellation. In the second case, all the transmit antennas are detected jointly. The comparison of the two cases shows improvement with the latter one, both in single-user and multiuser communications and in the presence of unknown cochannel interference (UCCI. It is further shown that in the multiuser case, the proposed receivers approach the corresponding single-user bounds. The number of receive antenna elements required to achieve single-user bound is thereby equal to the number of users and not to the total number of transmit antennas.

  16. Theoretical Limits on Multiuser Molecular Communication in Internet of Nano-Bio Things.

    Science.gov (United States)

    Dinc, Ergin; Akan, Ozgur B

    2017-06-01

    In nano-bio networks, multiple transmitter-receiver pairs will operate in the same medium. Both inter-symbol interference and multi-user interference can cause saturation at the receiver side, and this effect may cause an outage. Thus, we propose a tractable framework to calculate the theoretical operating points for fully absorbing receiver.

  17. An Improved User Selection Algorithm in Multiuser MIMO Broadcast with Channel Prediction

    Science.gov (United States)

    Min, Zhi; Ohtsuki, Tomoaki

    In multiuser MIMO-BC (Multiple-Input Multiple-Output Broadcasting) systems, user selection is important to achieve multiuser diversity. The optimal user selection algorithm is to try all the combinations of users to find the user group that can achieve the multiuser diversity. Unfortunately, the high calculation cost of the optimal algorithm prevents its implementation. Thus, instead of the optimal algorithm, some suboptimal user selection algorithms were proposed based on semiorthogonality of user channel vectors. The purpose of this paper is to achieve multiuser diversity with a small amount of calculation. For this purpose, we propose a user selection algorithm that can improve the orthogonality of a selected user group. We also apply a channel prediction technique to a MIMO-BC system to get more accurate channel information at the transmitter. Simulation results show that the channel prediction can improve the accuracy of channel information for user selections, and the proposed user selection algorithm achieves higher sum rate capacity than the SUS (Semiorthogonal User Selection) algorithm. Also we discuss the setting of the algorithm threshold. As the result of a discussion on the calculation complexity, which uses the number of complex multiplications as the parameter, the proposed algorithm is shown to have a calculation complexity almost equal to that of the SUS algorithm, and they are much lower than that of the optimal user selection algorithm.

  18. Studying the Effectiveness of Multi-User Immersive Environments for Collaborative Evaluation Tasks

    Science.gov (United States)

    Lorenzo, Carlos-Miguel; Sicilia, Miguel Angel; Sanchez, Salvador

    2012-01-01

    Massively Multiuser On-line Learning (MMOL) Platforms, often called "virtual learning worlds", constitute a still unexplored context for communication-enhanced learning, where synchronous communication skills in an explicit social setting enhance the potential of effective collaboration. In this paper, we report on an experimental study of…

  19. Arsanilic acid blindness in pigs

    Energy Technology Data Exchange (ETDEWEB)

    Menges, R.W.; Kintner, L.D.; Selby, L.A.; Stewart, R.W.; Marlenfeld, C.J.

    1970-06-01

    Blindness in pigs that were given an overdosage of arsanilic acid is reported. A 0.0375% level of arsanilic acid was fed to 640 pigs for 90 days beginning when the animals were 3 months old. Approximately one month after the start of feeding, partial or complete blindness was observed in 50 of the pigs. Clinical signs, pathologic findings and the chemical analysis of hair are discussed. The level of arsanilic acid used was that recommended for the control of swine dysentery, to be fed for only five or six days. The overdosage resulted from a misunderstanding between the farmer and the feed mill.

  20. Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF/FSO Relay Networks With Opportunistic User Scheduling

    KAUST Repository

    El-Malek, Ahmed H. Abd; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2016-01-01

    In this paper, we study the performance of multiuser single-input multiple-output mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling. The considered system includes multiple users, one amplify

  1. Enhancing Physical Layer Security of Multiuser SIMO Mixed RF/FSO Relay Networks with Multi-Eavesdroppers

    KAUST Repository

    El-Malek, Ahmed H. Abd; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, we investigate the secrecy performance of multiuser (MU) single-input multiple-output (SIMO) mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling and multiple eavesdropping attacks

  2. A Robotic Coach Architecture for Elder Care (ROCARE) Based on Multi-User Engagement Models.

    Science.gov (United States)

    Fan, Jing; Bian, Dayi; Zheng, Zhi; Beuscher, Linda; Newhouse, Paul A; Mion, Lorraine C; Sarkar, Nilanjan

    2017-08-01

    The aging population with its concomitant medical conditions, physical and cognitive impairments, at a time of strained resources, establishes the urgent need to explore advanced technologies that may enhance function and quality of life. Recently, robotic technology, especially socially assistive robotics has been investigated to address the physical, cognitive, and social needs of older adults. Most system to date have predominantly focused on one-on-one human robot interaction (HRI). In this paper, we present a multi-user engagement-based robotic coach system architecture (ROCARE). ROCARE is capable of administering both one-on-one and multi-user HRI, providing implicit and explicit channels of communication, and individualized activity management for long-term engagement. Two preliminary feasibility studies, a one-on-one interaction and a triadic interaction with two humans and a robot, were conducted and the results indicated potential usefulness and acceptance by older adults, with and without cognitive impairment.

  3. QoE-based transmission strategies for multi-user wireless information and power transfer

    Directory of Open Access Journals (Sweden)

    Taehun Jung

    2015-12-01

    Full Text Available One solution to the problem of supplying energy to wireless networks is wireless power transfer. One such technology–electromagnetic radiation enabled wireless power transfer–will change traditional wireless networks. In this paper, we investigate a transmission strategy for multi-user wireless information and power transfer. We consider a multi-user multiple-input multiple-output (MIMO channel that includes one base station (BS and two user terminals (UT consisting of one energy harvesting (EH receiver and one information decoding (ID receiver. Our system provides transmission strategies that can be executed and implemented in practical scenarios. The paper then analyzes the rate–energy (R–E pair of our strategies and compares them to those of the theoretical optimal strategy. We furthermore propose a QoE-based mode selection algorithm by mapping the R–E pair to the utility functions.

  4. Multiuser Radio Resource Allocation for Multiservice Transmission in OFDMA-Based Cooperative Relay Networks

    Directory of Open Access Journals (Sweden)

    Zhang Xing

    2009-01-01

    Full Text Available Abstract The problem of multiservice transmission in OFDMA-based cooperative relay networks is studied comprehensively. We propose a framework to adaptively allocate power, subcarriers, and data rate in OFDMA system to maximize spectral efficiency under the constraints of satisfying multiuser multiservices' QoS requirements. Specifically, first we concentrate on the single-user scenario which considers multiservice transmission in point-to-point cooperative relay network. Based on the analysis of single-user scenario, we extend the multiservice transmission to multiuser point-to-multipoint scenario. Next, based on the framework, we propose several suboptimal radio resource allocation algorithms for multiservice transmissions in OFDMA-based cooperative relay networks to further reduce the computational complexity. Simulation results show that the proposed algorithms yield much higher spectral efficiency and much lower outage probability, which are flexible and efficient for the OFDMA-based cooperative relay system.

  5. Multiuser Diversity with Adaptive Modulation in Non-Identically Distributed Nakagami Fading Environments

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In this paper, we analyze the performance of adaptive modulation with single-cell multiuser scheduling over independent but not identical distributed (i.n.i.d.) Nakagami fading channels. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded/coded M-ary quadrature amplitude modulation (M-QAM) schemes. We also study the impact of time delay on the average BER of adaptive M-QAM. Selected numerical results show that the multiuser diversity brings a considerably better performance even over i.n.i.d. fading environments.

  6. An Approach to Optimum Joint Beamforming Design in a MIMO-OFDM Multiuser System

    Directory of Open Access Journals (Sweden)

    Pascual-Iserte Antonio

    2004-01-01

    Full Text Available This paper describes a multiuser scenario with several terminals acceding simultaneously to the same frequency channel. The objective is to design an optimal multiuser system that may be used as a comparative framework when evaluating other suboptimal solutions and to contribute to the already published works on this topic. The present work assumes that a centralized manager knows perfectly all the channel responses between all the terminals. According to this, the transmitters and receivers, using antenna arrays and leading to the so-called multiple-input-multiple-output (MIMO channels, are designed in a joint beamforming approach, attempting to minimize the total transmit power subject to quality of service (QoS constraints. Since this optimization problem is not convex, the use of the simulated annealing (SA technique is proposed to find the optimum solution.

  7. An Iterative Multiuser Detector for Turbo-Coded DS-CDMA Systems

    Directory of Open Access Journals (Sweden)

    Takawira Fambirai

    2005-01-01

    Full Text Available We propose an iterative multiuser detector for turbo-coded synchronous and asynchronous direct-sequence CDMA (DS-CDMA systems. The receiver is derived from the maximum a posteriori (MAP estimation of the single user's transmitted data, conditioned on information about the estimate of the multiple-access interference (MAI and the received signal from the channel. This multiple-access interference is reconstructed by making hard decisions on the users' detected bits at the preceding iteration. The complexity of the proposed receiver increases linearly with the number of users. The proposed detection scheme is compared with a previously developed one. The multiuser detector proposed in this paper has a better performance when the transmitted powers of all active users are equal in the additive white Gaussian noise (AWGN channel. Also, the detector is found to be resilient against the near-far effect.

  8. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park

    Science.gov (United States)

    Sim, Vivian X. Y.; Dafforn, Katherine A.; Simpson, Stuart L.; Kelaher, Brendan P.; Johnston, Emma L.

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management. PMID:26086427

  9. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park.

    Science.gov (United States)

    Sim, Vivian X Y; Dafforn, Katherine A; Simpson, Stuart L; Kelaher, Brendan P; Johnston, Emma L

    2015-01-01

    Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ) where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina) in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.

  10. Sediment Contaminants and Infauna Associated with Recreational Boating Structures in a Multi-Use Marine Park.

    Directory of Open Access Journals (Sweden)

    Vivian X Y Sim

    Full Text Available Multi-use marine parks achieve conservation through spatial management of activities. Zoning of marine parks in New South Wales, Australia, includes high conservation areas and special purpose zones (SPZ where maritime activities are concentrated. Although such measures geographically constrain anthropogenic impacts, we have limited understanding of potential ecological effects. We assessed sediment communities and contaminants adjacent to boating infrastructure (boat ramps, jetties and a marina in a SPZ from the Clyde Estuary in Batemans Marine Park. Metal concentrations and fines content were elevated at boating structures compared to reference sites. Species richness was higher at sites with boating structures, where capitellid polychaetes and nematodes dominated the communities. Changes associated with boating structures were localised and did not extend beyond breakwalls or to reference sites outside the SPZ. The study highlights the benefits of appropriate zoning in a multi-use marine park and the potential to minimise stress on pristine areas through the application of spatial management.

  11. Leakage based precoding for multi-user MIMO-OFDM systems

    KAUST Repository

    Sadek, Mirette

    2011-08-01

    In downlink multi-user multiple-input multiple-output (MIMO) transmissions, several precoding schemes have been proposed to decrease interference among users. Notable among these precoding schemes is one that uses the signal-to-leakage-plus-noise ratio (SLNR) as an optimization criterion. In this paper, leveraging the efficiency of the SLNR optimization, we generalize this precoding scheme to MIMO orthogonal frequency division multiplexing (OFDM) multi-user systems where the OFDM is used to overcome the inter-symbol- interference (ISI) introduced by multipath channels. We also introduce a channel compensation technique that reconstructs the channel at the transmitter for every time instant given a significantly lower channel feedback rate by the receiver. © 2006 IEEE.

  12. Mechanisms for collaboration: a design and evaluation framework for multi-user interfaces

    OpenAIRE

    Yuill, Nicola; Rogers, Yvonne

    2012-01-01

    Multi-user interfaces are said to provide “natural” interaction in supporting collaboration, compared to individual and noncolocated technologies. We identify three mechanisms accounting for the success of such interfaces: high awareness of others' actions and intentions, high control over the interface, and high availability of background information. We challenge the idea that interaction over such interfaces is necessarily “natural” and argue that everyday interaction involves constraints ...

  13. Multi-user software of radio therapeutical calculation using a computational network

    International Nuclear Information System (INIS)

    Allaucca P, J.J.; Picon C, C.; Zaharia B, M.

    1998-01-01

    It has been designed a hardware and software system for a radiotherapy Department. It runs under an Operative system platform Novell Network sharing the existing resources and of the server, it is centralized, multi-user and of greater safety. It resolves a variety of problems and calculation necessities, patient steps and administration, it is very fast and versatile, it contains a set of menus and options which may be selected with mouse, direction arrows or abbreviated keys. (Author)

  14. Impact of Channel Estimation Errors on Multiuser Detection via the Replica Method

    Directory of Open Access Journals (Sweden)

    Li Husheng

    2005-01-01

    Full Text Available For practical wireless DS-CDMA systems, channel estimation is imperfect due to noise and interference. In this paper, the impact of channel estimation errors on multiuser detection (MUD is analyzed under the framework of the replica method. System performance is obtained in the large system limit for optimal MUD, linear MUD, and turbo MUD, and is validated by numerical results for finite systems.

  15. Antimicrobial efficacy assessment of multi-use solution to disinfect hydrophilic contact lens, in vitro

    OpenAIRE

    Lui,Aline Cristina Fioravanti; Netto,Adamo Lui; Silva,Cely Barreto da; Hida,Richard; Mendes,Thais Sousa; Lui,Giovana Arlene Fioravanti; Gemperli,Daniela Barbosa; Vital,Enderson Dantas

    2009-01-01

    PURPOSE: To evaluate the efficacy of disinfecting solutions in hydrophilic contact lenses (CL). METHODS: Two multi-use solutions denominated solution A (0.001% polyquaternium-1 and 0.0005% myristamidopropyl dimethylamine) and solution B (0.0001% polyaminopropyl biguanide) were used. The solutions were tested in hydrophilic contact lenses infected with Pseudomonas aeruginosa (ATCC27583), Staphylococcus epidermidis (ATCC1226), Klebsiella pneumoniae (ATCC13883), Staphylococcus aureus (ATCC25923)...

  16. Uplink transmit beamforming design for SINR maximization with full multiuser channel state information

    Science.gov (United States)

    Xi, Songnan; Zoltowski, Michael D.

    2008-04-01

    Multiuser multiple-input multiple-output (MIMO) systems are considered in this paper. We continue our research on uplink transmit beamforming design for multiple users under the assumption that the full multiuser channel state information, which is the collection of the channel state information between each of the users and the base station, is known not only to the receiver but also to all the transmitters. We propose an algorithm for designing optimal beamforming weights in terms of maximizing the signal-to-interference-plus-noise ratio (SINR). Through statistical modeling, we decouple the original mathematically intractable optimization problem and achieved a closed-form solution. As in our previous work, the minimum mean-squared error (MMSE) receiver with successive interference cancellation (SIC) is adopted for multiuser detection. The proposed scheme is compared with an existing jointly optimized transceiver design, referred to as the joint transceiver in this paper, and our previously proposed eigen-beamforming algorithm. Simulation results demonstrate that our algorithm, with much less computational burden, accomplishes almost the same performance as the joint transceiver for spatially independent MIMO channel and even better performance for spatially correlated MIMO channels. And it always works better than our previously proposed eigen beamforming algorithm.

  17. Iterative Multiuser Equalization for Subconnected Hybrid mmWave Massive MIMO Architecture

    Directory of Open Access Journals (Sweden)

    R. Magueta

    2017-01-01

    Full Text Available Millimeter waves and massive MIMO are a promising combination to achieve the multi-Gb/s required by future 5G wireless systems. However, fully digital architectures are not feasible due to hardware limitations, which means that there is a need to design signal processing techniques for hybrid analog-digital architectures. In this manuscript, we propose a hybrid iterative block multiuser equalizer for subconnected millimeter wave massive MIMO systems. The low complexity user-terminals employ pure-analog random precoders, each with a single RF chain. For the base station, a subconnected hybrid analog-digital equalizer is designed to remove multiuser interference. The hybrid equalizer is optimized using the average bit-error-rate as a metric. Due to the coupling between the RF chains in the optimization problem, the computation of the optimal solutions is too complex. To address this problem, we compute the analog part of the equalizer sequentially over the RF chains using a dictionary built from the array response vectors. The proposed subconnected hybrid iterative multiuser equalizer is compared with a recently proposed fully connected approach. The results show that the performance of the proposed scheme is close to the fully connected hybrid approach counterpart after just a few iterations.

  18. Multiuser receiver for DS-CDMA signals in multipath channels: an enhanced multisurface method.

    Science.gov (United States)

    Mahendra, Chetan; Puthusserypady, Sadasivan

    2006-11-01

    This paper deals with the problem of multiuser detection in direct-sequence code-division multiple-access (DS-CDMA) systems in multipath environments. The existing multiuser detectors can be divided into two categories: (1) low-complexity poor-performance linear detectors and (2) high-complexity good-performance nonlinear detectors. In particular, in channels where the orthogonality of the code sequences is destroyed by multipath, detectors with linear complexity perform much worse than the nonlinear detectors. In this paper, we propose an enhanced multisurface method (EMSM) for multiuser detection in multipath channels. EMSM is an intermediate piecewise linear detection scheme with a run-time complexity linear in the number of users. Its bit error rate performance is compared with existing linear detectors, a nonlinear radial basis function detector trained by the new support vector learning algorithm, and Verdu's optimal detector. Simulations in multipath channels, for both synchronous and asynchronous cases, indicate that it always outperforms all other linear detectors, performing nearly as well as nonlinear detectors.

  19. Multi-User Virtual Reality Therapy for Post-Stroke Hand Rehabilitation at Home

    Directory of Open Access Journals (Sweden)

    Daria Tsoupikova

    2016-04-01

    Full Text Available Our paper describes the development of a novel multi-user virtual reality (VR system for post-stroke rehabilitation that can be used independently in the home to improve upper extremity motor function. This is the pre-clinical phase of an ongoing collaborative, interdisciplinary research project at the Rehabilitation Institute of Chicago involving a team of engineers, researchers, occupational therapists and artists. This system was designed for creative collaboration within a virtual environment to increase patients' motivation, further engagement and to alleviate the impact of social isolation following stroke. This is a low-cost system adapted to everyday environments and designed to run on a personal computer that combines three VR environments with audio integration, wireless Kinect tracking and hand motion tracking sensors. Three different game exercises for this system were developed to encourage repetitive task practice, collaboration and competitive interaction. The system is currently being tested with 15 subjects in three settings: a multi-user VR, a single-user VR and at a tabletop with standard exercises to examine the level of engagement and to compare resulting functional performance across methods. We hypothesize that stroke survivors will become more engaged in therapy when training with a multi-user VR system and this will translate into greater gains.

  20. DEEP SPACE: High Resolution VR Platform for Multi-user Interactive Narratives

    Science.gov (United States)

    Kuka, Daniela; Elias, Oliver; Martins, Ronald; Lindinger, Christopher; Pramböck, Andreas; Jalsovec, Andreas; Maresch, Pascal; Hörtner, Horst; Brandl, Peter

    DEEP SPACE is a large-scale platform for interactive, stereoscopic and high resolution content. The spatial and the system design of DEEP SPACE are facing constraints of CAVETM-like systems in respect to multi-user interactive storytelling. To be used as research platform and as public exhibition space for many people, DEEP SPACE is capable to process interactive, stereoscopic applications on two projection walls with a size of 16 by 9 meters and a resolution of four times 1080p (4K) each. The processed applications are ranging from Virtual Reality (VR)-environments to 3D-movies to computationally intensive 2D-productions. In this paper, we are describing DEEP SPACE as an experimental VR platform for multi-user interactive storytelling. We are focusing on the system design relevant for the platform, including the integration of the Apple iPod Touch technology as VR control, and a special case study that is demonstrating the research efforts in the field of multi-user interactive storytelling. The described case study, entitled "Papyrate's Island", provides a prototypical scenario of how physical drawings may impact on digital narratives. In this special case, DEEP SPACE helps us to explore the hypothesis that drawing, a primordial human creative skill, gives us access to entirely new creative possibilities in the domain of interactive storytelling.

  1. Smart LED allocation scheme for efficient multiuser visible light communication networks.

    Science.gov (United States)

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon Ho

    2015-05-18

    In a multiuser bidirectional visible light communication (VLC), a large number of LEDs or an LED array needs to be allocated in an efficient manner to ensure sustainable data rate and link quality. Moreover, in order to support an increasing or decreasing number of users in the network, the LED allocation is required to be performed dynamically. In this paper, a novel smart LED allocation scheme for efficient multiuser VLC networks is presented. The proposed scheme allocates RGB LEDs to multiple users in a dynamic and efficient fashion, while satisfying illumination requirements in an indoor environment. The smart LED array comprised of RGB LEDs is divided into sectors according to the location of the users. The allocated sectors then provide optical power concentration toward the users for efficient and reliable data transmission. An algorithm for the dynamic allocation of the LEDs is also presented. To verify its effective resource allocation feature of the proposed scheme, simulations were performed. It is found that the proposed smart LED allocation scheme provides the effect of optical beamforming toward individual users, thereby increasing the collective power concentration of the optical signals on the desirable users and resulting in significantly increased data rate, while ensuring sufficient illumination in a multiuser VLC environment.

  2. Optimal Multiuser Diversity in Multi-Cell MIMO Uplink Networks: User Scaling Law and Beamforming Design

    Directory of Open Access Journals (Sweden)

    Bang Chul Jung

    2017-07-01

    Full Text Available We introduce a distributed protocol to achieve multiuser diversity in a multicell multiple-input multiple-output (MIMO uplink network, referred to as a MIMO interfering multiple-access channel (IMAC. Assuming both no information exchange among base stations (BS and local channel state information at the transmitters for the MIMO IMAC, we propose a joint beamforming and user scheduling protocol, and then show that the proposed protocol can achieve the optimal multiuser diversity gain, i.e., KMlog(SNRlog N, as long as the number of mobile stations (MSs in a cell, N, scales faster than SNR K M − L 1 − ϵ for a small constant ϵ > 0, where M, L, K, and SNR denote the number of receive antennas at each BS, the number of transmit antennas at each MS, the number of cells, and the signal-to-noise ratio, respectively. Our result indicates that multiuser diversity can be achieved in the presence of intra-cell and inter-cell interference even in a distributed fashion. As a result, vital information on how to design distributed algorithms in interference-limited cellular environments is provided.

  3. Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies

    Science.gov (United States)

    Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon-Ho

    2015-10-01

    In optical wireless communications, multiple channel transmission is an attractive solution to enhancing capacity and system performance. A new modulation scheme called color coded multiple access (CCMA) for bidirectional multiuser visible light communications (VLC) is presented for smart home applications. The proposed scheme uses red, green and blue (RGB) light emitting diodes (LED) for downlink and phosphor based white LED (P-LED) for uplink to establish a bidirectional VLC and also employs orthogonal codes to support multiple users and devices. The downlink transmission for data user devices and smart home devices is provided using red and green colors from the RGB LEDs, respectively, while uplink transmission from both types of devices is performed using the blue color from P-LEDs. Simulations are conducted to verify the performance of the proposed scheme. It is found that the proposed bidirectional multiuser scheme is efficient in terms of data rate and performance. In addition, since the proposed scheme uses RGB signals for downlink data transmission, it provides flicker-free illumination that would lend itself to multiuser VLC system for smart home applications.

  4. A Multiuser Detector Based on Artificial Bee Colony Algorithm for DS-UWB Systems

    Directory of Open Access Journals (Sweden)

    Zhendong Yin

    2013-01-01

    Full Text Available Artificial Bee Colony (ABC algorithm is an optimization algorithm based on the intelligent behavior of honey bee swarm. The ABC algorithm was developed to solve optimizing numerical problems and revealed premising results in processing time and solution quality. In ABC, a colony of artificial bees search for rich artificial food sources; the optimizing numerical problems are converted to the problem of finding the best parameter which minimizes an objective function. Then, the artificial bees randomly discover a population of initial solutions and then iteratively improve them by employing the behavior: moving towards better solutions by means of a neighbor search mechanism while abandoning poor solutions. In this paper, an efficient multiuser detector based on a suboptimal code mapping multiuser detector and artificial bee colony algorithm (SCM-ABC-MUD is proposed and implemented in direct-sequence ultra-wideband (DS-UWB systems under the additive white Gaussian noise (AWGN channel. The simulation results demonstrate that the BER and the near-far effect resistance performances of this proposed algorithm are quite close to those of the optimum multiuser detector (OMD while its computational complexity is much lower than that of OMD. Furthermore, the BER performance of SCM-ABC-MUD is not sensitive to the number of active users and can obtain a large system capacity.

  5. RACOON: a multiuser QoS design for mobile wireless body area networks.

    Science.gov (United States)

    Cheng, Shihheng; Huang, Chingyao; Tu, Chun Chen

    2011-10-01

    In this study, Random Contention-based Resource Allocation (RACOON) medium access control (MAC) protocol is proposed to support the quality of service (QoS) for multi-user mobile wireless body area networks (WBANs). Different from existing QoS designs that focus on a single WBAN, a multiuser WBAN QoS should further consider both inter-WBAN interference and inter-WBAN priorities. Similar problems have been studied in both overlapped wireless local area networks (WLANs) and Bluetooth piconets that need QoS supports. However, these solutions are designed for non-medical transmissions that do not consider any priority scheme for medical applications. Most importantly, these studies focus on only static or low mobility networks. Network mobility of WBANs will introduce unnecessary inter-network collisions and energy waste, which are not considered by these solutions. The proposed multiuser-QoS protocol, RACOON, simultaneously satisfies the inter WBAN QoS requirements and overcomes the performance degradation caused by WBAN mobility. Simulation results verify that RACOON provides better latency and energy control, as compared with WBAN QoS protocols without considering the inter-WBAN requirements.

  6. Partial Cancellation

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Partial Cancellation. Full Cancellation is desirable. But complexity requirements are enormous. 4000 tones, 100 Users billions of flops !!! Main Idea: Challenge: To determine which cross-talker to cancel on what “tone” for a given victim. Constraint: Total complexity is ...

  7. Inspiring Equal Contribution and Opportunity in a 3D Multi-User Virtual Environment: Bringing Together Men Gamers and Women Non-Gamers in Second Life[R

    Science.gov (United States)

    deNoyelles, Aimee; Seo, Kay Kyeong-Ju

    2012-01-01

    A 3D multi-user virtual environment holds promise to support and enhance student online learning communities due to its ability to promote global synchronous interaction and collaboration, rich multisensory experience and expression, and elaborate design capabilities. Second Life[R], a multi-user virtual environment intended for adult users 18 and…

  8. Rehabilitation of cortical blindness secondary to stroke.

    Science.gov (United States)

    Gaber, Tarek A-Z K

    2010-01-01

    Cortical blindness is a rare complication of posterior circulation stroke. However, its complex presentation with sensory, physical, cognitive and behavioural impairments makes it one of the most challenging. Appropriate approach from a rehabilitation standpoint was never reported. Our study aims to discuss the rehabilitation methods and outcomes of a cohort of patients with cortical blindness. The notes of all patients with cortical blindness referred to a local NHS rehabilitation service in the last 6~years were examined. Patients' demographics, presenting symptoms, scan findings, rehabilitation programmes and outcomes were documented. Seven patients presented to our service, six of them were males. The mean age was 63. Patients 1, 2 and 3 had total blindness with severe cognitive and behavioural impairments, wandering and akathisia. All of them failed to respond to any rehabilitation effort and the focus was on damage limitation. Pharmacological interventions had a modest impact on behaviour and sleep pattern. The 3 patients were discharged to a nursing facility. Patients 4, 5, 6 and 7 had partial blindness with variable severity. All of them suffered from significant memory impairment. However, none suffered from any behavioural, physical or other cognitive impairment. Rehabilitation efforts on 3 patients were carried out collaboratively between brain injury occupational therapists and sensory disability officers. All patients experienced significant improvement in handicap and they all maintained community placements. This small cohort of patients suggests that the rehabilitation philosophy and outcomes of these 2 distinct groups of either total or partial cortical blindness differ significantly.

  9. Representing vision and blindness.

    Science.gov (United States)

    Ray, Patrick L; Cox, Alexander P; Jensen, Mark; Allen, Travis; Duncan, William; Diehl, Alexander D

    2016-01-01

    There have been relatively few attempts to represent vision or blindness ontologically. This is unsurprising as the related phenomena of sight and blindness are difficult to represent ontologically for a variety of reasons. Blindness has escaped ontological capture at least in part because: blindness or the employment of the term 'blindness' seems to vary from context to context, blindness can present in a myriad of types and degrees, and there is no precedent for representing complex phenomena such as blindness. We explore current attempts to represent vision or blindness, and show how these attempts fail at representing subtypes of blindness (viz., color blindness, flash blindness, and inattentional blindness). We examine the results found through a review of current attempts and identify where they have failed. By analyzing our test cases of different types of blindness along with the strengths and weaknesses of previous attempts, we have identified the general features of blindness and vision. We propose an ontological solution to represent vision and blindness, which capitalizes on resources afforded to one who utilizes the Basic Formal Ontology as an upper-level ontology. The solution we propose here involves specifying the trigger conditions of a disposition as well as the processes that realize that disposition. Once these are specified we can characterize vision as a function that is realized by certain (in this case) biological processes under a range of triggering conditions. When the range of conditions under which the processes can be realized are reduced beyond a certain threshold, we are able to say that blindness is present. We characterize vision as a function that is realized as a seeing process and blindness as a reduction in the conditions under which the sight function is realized. This solution is desirable because it leverages current features of a major upper-level ontology, accurately captures the phenomenon of blindness, and can be

  10. Partial Deconvolution with Inaccurate Blur Kernel.

    Science.gov (United States)

    Ren, Dongwei; Zuo, Wangmeng; Zhang, David; Xu, Jun; Zhang, Lei

    2017-10-17

    Most non-blind deconvolution methods are developed under the error-free kernel assumption, and are not robust to inaccurate blur kernel. Unfortunately, despite the great progress in blind deconvolution, estimation error remains inevitable during blur kernel estimation. Consequently, severe artifacts such as ringing effects and distortions are likely to be introduced in the non-blind deconvolution stage. In this paper, we tackle this issue by suggesting: (i) a partial map in the Fourier domain for modeling kernel estimation error, and (ii) a partial deconvolution model for robust deblurring with inaccurate blur kernel. The partial map is constructed by detecting the reliable Fourier entries of estimated blur kernel. And partial deconvolution is applied to wavelet-based and learning-based models to suppress the adverse effect of kernel estimation error. Furthermore, an E-M algorithm is developed for estimating the partial map and recovering the latent sharp image alternatively. Experimental results show that our partial deconvolution model is effective in relieving artifacts caused by inaccurate blur kernel, and can achieve favorable deblurring quality on synthetic and real blurry images.Most non-blind deconvolution methods are developed under the error-free kernel assumption, and are not robust to inaccurate blur kernel. Unfortunately, despite the great progress in blind deconvolution, estimation error remains inevitable during blur kernel estimation. Consequently, severe artifacts such as ringing effects and distortions are likely to be introduced in the non-blind deconvolution stage. In this paper, we tackle this issue by suggesting: (i) a partial map in the Fourier domain for modeling kernel estimation error, and (ii) a partial deconvolution model for robust deblurring with inaccurate blur kernel. The partial map is constructed by detecting the reliable Fourier entries of estimated blur kernel. And partial deconvolution is applied to wavelet-based and learning

  11. Interference Alignment-based Precoding and User Selection with Limited Feedback in Two-cell Downlink Multi-user MIMO Systems

    Directory of Open Access Journals (Sweden)

    Yin Zhu

    2016-05-01

    Full Text Available Interference alignment (IA is a new approach to address interference in modern multiple-input multiple-out (MIMO cellular networks in which interference is an important factor that limits the system throughput. System throughput in most IA implementation schemes is significantly improved only with perfect channel state information and in a high signal-to-noise ratio (SNR region. Designing a simple IA scheme for the system with limited feedback and investigating system performance at a low-to-medium SNR region is important and practical. This paper proposed a precoding and user selection scheme based on partial interference alignment in two-cell downlink multi-user MIMO systems under limited feedback. This scheme aligned inter-cell interference to a predefined direction by designing user’s receive antenna combining vectors. A modified singular value decomposition (SVD-based beamforming method and a corresponding user-selection algorithm were proposed for the system with low rate limited feedback to improve sum rate performance. Simulation results show that the proposed scheme achieves a higher sum rate than traditional schemes without IA. The modified SVD-based beamforming scheme is also superior to the traditional zero-forcing beamforming scheme in low-rate limited feedback systems. The proposed partial IA scheme does not need to collaborate between transmitters and joint design between the transmitter and the users. The scheme can be implemented with low feedback overhead in current MIMO cellular networks.

  12. Channel Selection Based on Trust and Multiarmed Bandit in Multiuser, Multichannel Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Fanzi Zeng

    2014-01-01

    Full Text Available This paper proposes a channel selection scheme for the multiuser, multichannel cognitive radio networks. This scheme formulates the channel selection as the multiarmed bandit problem, where cognitive radio users are compared to the players and channels to the arms. By simulation negotiation we can achieve the potential reward on each channel after it is selected for transmission; then the channel with the maximum accumulated rewards is formally chosen. To further improve the performance, the trust model is proposed and combined with multi-armed bandit to address the channel selection problem. Simulation results validate the proposed scheme.

  13. A Suboptimal Scheme for Multi-User Scheduling in Gaussian Broadcast Channels

    KAUST Repository

    Zafar, Ammar; Alouini, Mohamed-Slim; Shaqfeh, Mohammad

    2014-01-01

    This work proposes a suboptimal multi-user scheduling scheme for Gaussian broadcast channels which improves upon the classical single user selection, while considerably reducing complexity as compared to the optimal superposition coding with successful interference cancellation. The proposed scheme combines the two users with the maximum weighted instantaneous rate using superposition coding. The instantaneous rate and power allocation are derived in closed-form, while the long term rate of each user is derived in integral form for all channel distributions. Numerical results are then provided to characterize the prospected gains of the proposed scheme.

  14. Sum Rate Maximization using Linear Precoding and Decoding in the Multiuser MIMO Downlink

    OpenAIRE

    Tenenbaum, Adam J.; Adve, Raviraj S.

    2008-01-01

    We propose an algorithm to maximize the instantaneous sum data rate transmitted by a base station in the downlink of a multiuser multiple-input, multiple-output system. The transmitter and the receivers may each be equipped with multiple antennas and each user may receive more than one data stream. We show that maximizing the sum rate is closely linked to minimizing the product of mean squared errors (PMSE). The algorithm employs an uplink/downlink duality to iteratively design transmit-recei...

  15. A Suboptimal Scheme for Multi-User Scheduling in Gaussian Broadcast Channels

    KAUST Repository

    Zafar, Ammar

    2014-05-28

    This work proposes a suboptimal multi-user scheduling scheme for Gaussian broadcast channels which improves upon the classical single user selection, while considerably reducing complexity as compared to the optimal superposition coding with successful interference cancellation. The proposed scheme combines the two users with the maximum weighted instantaneous rate using superposition coding. The instantaneous rate and power allocation are derived in closed-form, while the long term rate of each user is derived in integral form for all channel distributions. Numerical results are then provided to characterize the prospected gains of the proposed scheme.

  16. Support vector machine multiuser receiver for DS-CDMA signals in multipath channels.

    Science.gov (United States)

    Chen, S; Samingan, A K; Hanzo, L

    2001-01-01

    The problem of constructing an adaptive multiuser detector (MUD) is considered for direct sequence code division multiple access (DS-CDMA) signals transmitted through multipath channels. The emerging learning technique, called support vector machines (SVM), is proposed as a method of obtaining a nonlinear MUD from a relatively small training data block. Computer simulation is used to study this SVM MUD, and the results show that it can closely match the performance of the optimal Bayesian one-shot detector. Comparisons with an adaptive radial basis function (RBF) MUD trained by an unsupervised clustering algorithm are discussed.

  17. A CDMA multiuser detection algorithm on the basis of belief propagation

    International Nuclear Information System (INIS)

    Kabashima, Yoshiyuki

    2003-01-01

    An iterative algorithm for the multiuser detection problem that arises in code division multiple access (CDMA) systems is developed on the basis of Pearl's belief propagation (BP). We show that the BP-based algorithm exhibits nearly optimal performance in a practical time scale by utilizing the central limit theorem and self-averaging property appropriately, whereas direct application of BP to the detection problem is computationally difficult and far from practical. We further present close relationships of the proposed algorithm to the Thouless-Anderson-Palmer approach and replica analysis known in spin-glass research

  18. Cognitive radio networks with orthogonal space-time block coding and multiuser diversity

    KAUST Repository

    Yang, Liang

    2013-04-01

    This paper considers a multiuser spectrum sharing (SS) system operating in a Rayleigh fading environment and in which every node is equipped with multiple antennas. The system employs orthogonal space-time block coding at the secondary users. Under such a framework, the average capacity and error performance under a peak interference constraint are first analyzed. For a comparison purpose, an analysis of the transmit antenna selection scheme is also presented. Finally, some selected numerical results are presented to corroborate the proposed analysis. © 1997-2012 IEEE.

  19. On the performance of free-space optical communication systems with multiuser diversity

    KAUST Repository

    Yang, Liang

    2014-09-01

    Free space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over weak atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, and coverage are analyzed.

  20. Cognitive radio networks with orthogonal space-time block coding and multiuser diversity

    KAUST Repository

    Yang, Liang; Qaraqe, Khalid A.; Serpedin, Erchin; Alouini, Mohamed-Slim; Liu, Weiping

    2013-01-01

    This paper considers a multiuser spectrum sharing (SS) system operating in a Rayleigh fading environment and in which every node is equipped with multiple antennas. The system employs orthogonal space-time block coding at the secondary users. Under such a framework, the average capacity and error performance under a peak interference constraint are first analyzed. For a comparison purpose, an analysis of the transmit antenna selection scheme is also presented. Finally, some selected numerical results are presented to corroborate the proposed analysis. © 1997-2012 IEEE.

  1. Robots, multi-user virtual environments and healthcare: synergies for future directions.

    Science.gov (United States)

    Moon, Ajung; Grajales, Francisco J; Van der Loos, H F Machiel

    2011-01-01

    The adoption of technology in healthcare over the last twenty years has steadily increased, particularly as it relates to medical robotics and Multi-User Virtual Environments (MUVEs) such as Second Life. Both disciplines have been shown to improve the quality of care and have evolved, for the most part, in isolation from each other. In this paper, we present four synergies between medical robotics and MUVEs that have the potential to decrease resource utilization and improve the quality of healthcare delivery. We conclude with some foreseeable barriers and future research directions for researchers in these fields.

  2. Multiuser underwater acoustic communication using single-element virtual time reversal mirror

    Institute of Scientific and Technical Information of China (English)

    YIN JingWei; WANG YiLin; WANG Lei; HUI JunYing

    2009-01-01

    Pattern time delay shift coding (PDS) scheme is introduced and combined with spread spectrum tech-nique called SS-PDS for short which is power-saving and competent for long-range underwater acous-tic networks.Single-element virtual time reversal mirror (VTRM) is presented in this paper and validated by the lake trial results.Employing single-element VTRM in multiuser communication system based on SS-PDS can separate different users' information simultaneously at master node as indicated in the simulation results.

  3. Multi-user quantum key distribution based on Bell states with mutual authentication

    International Nuclear Information System (INIS)

    Lin Song; Huang Chuan; Liu Xiaofen

    2013-01-01

    A new multi-user quantum key distribution protocol with mutual authentication is proposed on a star network. Here, two arbitrary users are able to perform key distribution with the assistance of a semi-trusted center. Bell states are used as information carriers and transmitted in a quantum channel between the center and one user. A keyed hash function is utilized to ensure the identities of three parties. Finally, the security of this protocol with respect to various kinds of attacks is discussed. (paper)

  4. Reserch on energy absorption efficiency in full-duplex multi-user broadcast channel

    Directory of Open Access Journals (Sweden)

    JIANG Fengju

    2015-02-01

    Full Text Available This paper studies the user energy scenarios absorption efficiency optimization in multiuser broadcast channel.This paper assumed that the user terminals using full-duplex mode that the user receive uplink energy information and transfer uplink energy at the same time.In this paper,we maximize the minimum user uplink transmit power,when we ensure that each user′s energy absorption efficiency is greater than a threshold value and satisfies the premise of the base station downlink power emission limits.Finally,the simulation results confirm the effectiveness of the proposed algorithm.

  5. Multi-user MIMO and carrier aggregation in 4G systems

    DEFF Research Database (Denmark)

    Cattoni, Andrea Fabio; Nguyen, Hung Tuan; Duplicy, Jonathan

    2012-01-01

    The market success of broadband multimediaenabled devices such as smart phones, tablets, and laptops is increasing the demand for wireless data capacity in mobile cellular systems. In order to meet such requirements, the introduction of advanced techniques for increasing the efficiency in spectrum...... usage was required. Multi User -Multiple Input Multiple Output (MU-MIMO) and Carrier Aggregation (CA) are two important techniques addressed by 3GPP for LTE and LTE-Advanced. The aim of the EU FP7 project on ”Spectrum Aggregation and Multiuser-MIMO: real-World Impact” (SAMURAI) is to investigate...

  6. Partial processing

    International Nuclear Information System (INIS)

    1978-11-01

    This discussion paper considers the possibility of applying to the recycle of plutonium in thermal reactors a particular method of partial processing based on the PUREX process but named CIVEX to emphasise the differences. The CIVEX process is based primarily on the retention of short-lived fission products. The paper suggests: (1) the recycle of fission products with uranium and plutonium in thermal reactor fuel would be technically feasible; (2) it would, however, take ten years or more to develop the CIVEX process to the point where it could be launched on a commercial scale; (3) since the majority of spent fuel to be reprocessed this century will have been in storage for ten years or more, the recycling of short-lived fission products with the U-Pu would not provide an effective means of making refabrication fuel ''inaccessible'' because the radioactivity associated with the fission products would have decayed. There would therefore be no advantage in partial processing

  7. Partial gigantism

    Directory of Open Access Journals (Sweden)

    М.М. Karimova

    2017-05-01

    Full Text Available A girl with partial gigantism (the increased I and II fingers of the left foot is being examined. This condition is a rare and unresolved problem, as the definite reason of its development is not determined. Wait-and-see strategy is recommended, as well as correcting operations after closing of growth zones, and forming of data pool for generalization and development of schemes of drug and radial therapeutic methods.

  8. Sum-rate analysis of spectrum sharing spatial multiplexing MIMO systems with zero-forcing and multiuser diversity

    KAUST Repository

    Yang, Liang

    2013-06-01

    This paper considers a multiuser spectrum sharing (SS) multiple-input multiple-output (MIMO) system with zero-forcing (ZF) operating in a Rayleigh fading environment. We provide an asymptotic sum-rate analysis to investigate the effects of different parameters on the multiuser diversity gain. For a ZF SS spatial multiplexing system with scheduling, the asymptotic sum-rate scales like Nt log2(Q(Nt Np√K - 1)/N t), where Np denotes the number of antennas of primary receiver, Q is the interference temperature, and K represents the number of secondary transmitters. © 2013 IEEE.

  9. Photogenic partial seizures.

    Science.gov (United States)

    Hennessy, M J; Binnie, C D

    2000-01-01

    To establish the incidence and symptoms of partial seizures in a cohort of patients investigated on account of known sensitivity to intermittent photic stimulation and/or precipitation of seizures by environmental visual stimuli such as television (TV) screens or computer monitors. We report 43 consecutive patients with epilepsy, who had exhibited a significant EEG photoparoxysmal response or who had seizures precipitated by environmental visual stimuli and underwent detailed assessment of their photosensitivity in the EEG laboratory, during which all were questioned concerning their ictal symptoms. All patients were considered on clinical grounds to have an idiopathic epilepsy syndrome. Twenty-eight (65%) patients reported visually precipitated attacks occurring initially with maintained consciousness, in some instances evolving to a period of confusion or to a secondarily generalized seizure. Visual symptoms were most commonly reported and included positive symptoms such as coloured circles or spots, but also blindness and subjective symptoms such as "eyes going funny." Other symptoms described included nonspecific cephalic sensations, deja-vu, auditory hallucinations, nausea, and vomiting. No patient reported any clear spontaneous partial seizures, and there were no grounds for supposing that any had partial epilepsy excepting the ictal phenomenology of some or all of the visually induced attacks. These findings provide clinical support for the physiological studies that indicate that the trigger mechanism for human photosensitivity involves binocularly innervated cells located in the visual cortex. Thus the visual cortex is the seat of the primary epileptogenic process, and the photically triggered discharges and seizures may be regarded as partial with secondary generalization.

  10. Blind Quantum Signature with Blind Quantum Computation

    Science.gov (United States)

    Li, Wei; Shi, Ronghua; Guo, Ying

    2017-04-01

    Blind quantum computation allows a client without quantum abilities to interact with a quantum server to perform a unconditional secure computing protocol, while protecting client's privacy. Motivated by confidentiality of blind quantum computation, a blind quantum signature scheme is designed with laconic structure. Different from the traditional signature schemes, the signing and verifying operations are performed through measurement-based quantum computation. Inputs of blind quantum computation are securely controlled with multi-qubit entangled states. The unique signature of the transmitted message is generated by the signer without leaking information in imperfect channels. Whereas, the receiver can verify the validity of the signature using the quantum matching algorithm. The security is guaranteed by entanglement of quantum system for blind quantum computation. It provides a potential practical application for e-commerce in the cloud computing and first-generation quantum computation.

  11. Fair quantum blind signatures

    International Nuclear Information System (INIS)

    Tian-Yin, Wang; Qiao-Yan, Wen

    2010-01-01

    We present a new fair blind signature scheme based on the fundamental properties of quantum mechanics. In addition, we analyse the security of this scheme, and show that it is not possible to forge valid blind signatures. Moreover, comparisons between this scheme and public key blind signature schemes are also discussed. (general)

  12. Bilinear modeling of EMG signals to extract user-independent features for multiuser myoelectric interface.

    Science.gov (United States)

    Matsubara, Takamitsu; Morimoto, Jun

    2013-08-01

    In this study, we propose a multiuser myoelectric interface that can easily adapt to novel users. When a user performs different motions (e.g., grasping and pinching), different electromyography (EMG) signals are measured. When different users perform the same motion (e.g., grasping), different EMG signals are also measured. Therefore, designing a myoelectric interface that can be used by multiple users to perform multiple motions is difficult. To cope with this problem, we propose for EMG signals a bilinear model that is composed of two linear factors: 1) user dependent and 2) motion dependent. By decomposing the EMG signals into these two factors, the extracted motion-dependent factors can be used as user-independent features. We can construct a motion classifier on the extracted feature space to develop the multiuser interface. For novel users, the proposed adaptation method estimates the user-dependent factor through only a few interactions. The bilinear EMG model with the estimated user-dependent factor can extract the user-independent features from the novel user data. We applied our proposed method to a recognition task of five hand gestures for robotic hand control using four-channel EMG signals measured from subject forearms. Our method resulted in 73% accuracy, which was statistically significantly different from the accuracy of standard nonmultiuser interfaces, as the result of a two-sample t -test at a significance level of 1%.

  13. An FPGA-based DS-CDMA multiuser demodulator employing adaptive multistage parallel interference cancellation

    Science.gov (United States)

    Li, Xinhua; Song, Zhenyu; Zhan, Yongjie; Wu, Qiongzhi

    2009-12-01

    Since the system capacity is severely limited, reducing the multiple access interfere (MAI) is necessary in the multiuser direct-sequence code division multiple access (DS-CDMA) system which is used in the telecommunication terminals data-transferred link system. In this paper, we adopt an adaptive multistage parallel interference cancellation structure in the demodulator based on the least mean square (LMS) algorithm to eliminate the MAI on the basis of overviewing various of multiuser dectection schemes. Neither a training sequence nor a pilot signal is needed in the proposed scheme, and its implementation complexity can be greatly reduced by a LMS approximate algorithm. The algorithm and its FPGA implementation is then derived. Simulation results of the proposed adaptive PIC can outperform some of the existing interference cancellation methods in AWGN channels. The hardware setup of mutiuser demodulator is described, and the experimental results based on it demonstrate that the simulation results shows large performance gains over the conventional single-user demodulator.

  14. On the Impact of User Distribution on Cooperative Spectrum Sensing and Data Transmission with Multiuser Diversity

    KAUST Repository

    Rao, Anlei

    2011-07-01

    In this thesis, we investigate the independent but not identically distributed (i.n.i.d.) situations for spectrum sensing and data transmission. In particular, we derive the false-alarm probability and the detection probability of cooperative spectrum sensing with the scheme of energy fusion over i.n.i.d. Nakagami fading channels. Then, the performance of adaptive modulation with single-cell multiuser scheduling over i.n.i.d. Nakagami fading channels is analyzed. Closed-form expressions are derived for the average channel capacity, spectral efficiency, and bit-error-rate (BER) for both constant-power variable-rate and variable-power variable-rate uncoded M- ary quadrature amplitude modulation (M-QAM) schemes. In addition, we study the impact of time delay on the average BER of adaptive M-QAM. From the selected numerical results, we can see that cooperative spectrum sensing and multiuser diversity brings considerably better performance even over i.n.i.d. fading environments.

  15. Interaction Control Protocols for Distributed Multi-user Multi-camera Environments

    Directory of Open Access Journals (Sweden)

    Gareth W Daniel

    2003-10-01

    Full Text Available Video-centred communication (e.g., video conferencing, multimedia online learning, traffic monitoring, and surveillance is becoming a customary activity in our lives. The management of interactions in such an environment is a complicated HCI issue. In this paper, we present our study on a collection of interaction control protocols for distributed multiuser multi-camera environments. These protocols facilitate different approaches to managing a user's entitlement for controlling a particular camera. We describe a web-based system that allows multiple users to manipulate multiple cameras in varying remote locations. The system was developed using the Java framework, and all protocols discussed have been incorporated into the system. Experiments were designed and conducted to evaluate the effectiveness of these protocols, and to enable the identification of various human factors in a distributed multi-user and multi-camera environment. This work provides an insight into the complexity associated with the interaction management in video-centred communication. It can also serve as a conceptual and experimental framework for further research in this area.

  16. An improved reconstruction algorithm based on multi-user detection for uplink grant-free NOMA

    Directory of Open Access Journals (Sweden)

    Hou Chengyan

    2017-01-01

    Full Text Available For the traditional orthogonal matching pursuit(OMP algorithm in multi-user detection(MUD for uplink grant-free NOMA, here is a poor BER performance, so in this paper we propose an temporal-correlation orthogonal matching pursuit algorithm(TOMP to realize muli-user detection. The core idea of the TOMP is to use the time correlation of the active user sets to achieve user activity and data detection in a number of continuous time slots. We use the estimated active user set in the current time slot as a priori information to estimate the active user sets for the next slot. By maintaining the active user set Tˆl of size K(K is the number of users, but modified in each iteration. Specifically, active user set is believed to be reliable in one iteration but shown error in another iteration, can be added to the set path delay Tˆl or removed from it. Theoretical analysis of the improved algorithm provide a guarantee that the multi-user can be successfully detected with a high probability. The simulation results show that the proposed scheme can achieve better bit error rate (BER performance in the uplink grant-free NOMA system.

  17. The right view from the wrong location: depth perception in stereoscopic multi-user virtual environments.

    Science.gov (United States)

    Pollock, Brice; Burton, Melissa; Kelly, Jonathan W; Gilbert, Stephen; Winer, Eliot

    2012-04-01

    Stereoscopic depth cues improve depth perception and increase immersion within virtual environments (VEs). However, improper display of these cues can distort perceived distances and directions. Consider a multi-user VE, where all users view identical stereoscopic images regardless of physical location. In this scenario, cues are typically customized for one "leader" equipped with a head-tracking device. This user stands at the center of projection (CoP) and all other users ("followers") view the scene from other locations and receive improper depth cues. This paper examines perceived depth distortion when viewing stereoscopic VEs from follower perspectives and the impact of these distortions on collaborative spatial judgments. Pairs of participants made collaborative depth judgments of virtual shapes viewed from the CoP or after displacement forward or backward. Forward and backward displacement caused perceived depth compression and expansion, respectively, with greater compression than expansion. Furthermore, distortion was less than predicted by a ray-intersection model of stereo geometry. Collaboration times were significantly longer when participants stood at different locations compared to the same location, and increased with greater perceived depth discrepancy between the two viewing locations. These findings advance our understanding of spatial distortions in multi-user VEs, and suggest a strategy for reducing distortion.

  18. Adaptive Transmitter Optimization in Multiuser Multiantenna Systems: Theoretical Limits, Effect of Delays, and Performance Enhancements

    Directory of Open Access Journals (Sweden)

    Samardzija Dragan

    2005-01-01

    Full Text Available The advances in programmable and reconfigurable radios have rendered feasible transmitter optimization schemes that can greatly improve the performance of multiple-antenna multiuser systems. Reconfigurable radio platforms are particularly suitable for implementation of transmitter optimization at the base station. We consider the downlink of a wireless system with multiple transmit antennas at the base station and a number of mobile terminals (i.e., users each with a single receive antenna. Under an average transmit power constraint, we consider the maximum achievable sum data rates in the case of (1 zero-forcing (ZF spatial prefilter, (2 modified zero-forcing (MZF spatial prefilter, and (3 triangularization spatial prefilter coupled with dirty-paper coding (DPC transmission scheme. We show that the triangularization with DPC approaches the closed-loop MIMO rates (upper bound for higher SNRs. Further, the MZF solution performs very well for lower SNRs, while for higher SNRs, the rates for the ZF solution converge to the MZF rates. An important impediment that degrades the performance of such transmitter optimization schemes is the delay in channel state information (CSI. We characterize the fundamental limits of performance in the presence of delayed CSI and then propose performance enhancements using a linear MMSE predictor of the CSI that can be used in conjunction with transmitter optimization in multiple-antenna multiuser systems.

  19. A Multiuser Manufacturing Resource Service Composition Method Based on the Bees Algorithm

    Directory of Open Access Journals (Sweden)

    Yongquan Xie

    2015-01-01

    Full Text Available In order to realize an optimal resource service allocation in current open and service-oriented manufacturing model, multiuser resource service composition (RSC is modeled as a combinational and constrained multiobjective problem. The model takes into account both subjective and objective quality of service (QoS properties as representatives to evaluate a solution. The QoS properties aggregation and evaluation techniques are based on existing researches. The basic Bees Algorithm is tailored for finding a near optimal solution to the model, since the basic version is only proposed to find a desired solution in continuous domain and thus not suitable for solving the problem modeled in our study. Particular rules are designed for handling the constraints and finding Pareto optimality. In addition, the established model introduces a trusted service set to each user so that the algorithm could start by searching in the neighbor of more reliable service chains (known as seeds than those randomly generated. The advantages of these techniques are validated by experiments in terms of success rate, searching speed, ability of avoiding ingenuity, and so forth. The results demonstrate the effectiveness of the proposed method in handling multiuser RSC problems.

  20. Advancing MEMS Technology Usage through the MUMPS (Multi-User MEMS Processes) Program

    Science.gov (United States)

    Koester, D. A.; Markus, K. W.; Dhuler, V.; Mahadevan, R.; Cowen, A.

    1995-01-01

    In order to help provide access to advanced micro-electro-mechanical systems (MEMS) technologies and lower the barriers for both industry and academia, the Microelectronic Center of North Carolina (MCNC) and ARPA have developed a program which provides users with access to both MEMS processes and advanced electronic integration techniques. The four distinct aspects of this program, the multi-user MEMS processes (MUMP's), the consolidated micro-mechanical element library, smart MEMS, and the MEMS technology network are described in this paper. MUMP's is an ARPA-supported program created to provide inexpensive access to MEMS technology in a multi-user environment. It is both a proof-of-concept and educational tool that aids in the development of MEMS in the domestic community. MUMP's technologies currently include a 3-layer poly-silicon surface micromachining process and LIGA (lithography, electroforming, and injection molding) processes that provide reasonable design flexibility within set guidelines. The consolidated micromechanical element library (CaMEL) is a library of active and passive MEMS structures that can be downloaded by the MEMS community via the internet. Smart MEMS is the development of advanced electronics integration techniques for MEMS through the application of flip chip technology. The MEMS technology network (TechNet) is a menu of standard substrates and MEMS fabrication processes that can be purchased and combined to create unique process flows. TechNet provides the MEMS community greater flexibility and enhanced technology accessibility.

  1. Robust Transceivers Design for Multi-stream Multi-user MIMO Visible Light Communication

    KAUST Repository

    Sifaou, Houssem

    2017-11-27

    Visible light communication (VLC) is an emerging technique that uses light-emitting diodes to combine communication and illumination. It is considered as a promising scheme for indoor wireless communication that can be deployed at reduced costs, while offering high data rate performance. This paper focuses on the design of precoding and receiving schemes for downlink multi-user multiple-input multiple-output VLC systems using angle diversity receivers. Two major concerns need to be considered while solving such a problem. The first one is related to the inter-user interference, basically inherent to our consideration of a multi-user system, while the second results from the users’ mobility, causing imperfect channel estimates. To address both concerns, we propose robust precoding and receiver that solve the max-min SINR problem. The performance of the proposed VLC design is studied under different working conditions, where a significant gain of the proposed robust transceivers over their non-robust counterparts has been observed.

  2. Power-Controlled CDMA Cell Sectorization with Multiuser Detection: A Comprehensive Analysis on Uplink and Downlink

    Directory of Open Access Journals (Sweden)

    Aylin Yener

    2007-12-01

    Full Text Available We consider the joint optimization problem of cell sectorization, transmit power control and multiuser detection for a CDMA cell. Given the number of sectors and user locations, the cell is appropriately sectorized such that the total transmit power, as well as the receiver filters, is optimized. We formulate the corresponding joint optimization problems for both the uplink and the downlink and observe that in general, the resulting optimum transmit and receive beamwidth values for the directional antennas at the base station are different. We present the optimum solution under a general setting with arbitrary signature sets, multipath channels, realistic directional antenna responses and identify its complexity. We propose a low-complexity sectorization algorithm that performs near optimum and compare its performance with that of optimum solution. The results suggest that by intelligently combining adaptive cell sectorization, power control, and linear multiuser detection, we are able to increase the user capacity of the cell. Numerical results also indicate robustness of optimum sectorization against Gaussian channel estimation error.

  3. Power-Controlled CDMA Cell Sectorization with Multiuser Detection: A Comprehensive Analysis on Uplink and Downlink

    Directory of Open Access Journals (Sweden)

    Oh Changyoon

    2007-01-01

    Full Text Available We consider the joint optimization problem of cell sectorization, transmit power control and multiuser detection for a CDMA cell. Given the number of sectors and user locations, the cell is appropriately sectorized such that the total transmit power, as well as the receiver filters, is optimized. We formulate the corresponding joint optimization problems for both the uplink and the downlink and observe that in general, the resulting optimum transmit and receive beamwidth values for the directional antennas at the base station are different. We present the optimum solution under a general setting with arbitrary signature sets, multipath channels, realistic directional antenna responses and identify its complexity. We propose a low-complexity sectorization algorithm that performs near optimum and compare its performance with that of optimum solution. The results suggest that by intelligently combining adaptive cell sectorization, power control, and linear multiuser detection, we are able to increase the user capacity of the cell. Numerical results also indicate robustness of optimum sectorization against Gaussian channel estimation error.

  4. Robust Transceivers Design for Multi-stream Multi-user MIMO Visible Light Communication

    KAUST Repository

    Sifaou, Houssem; Kammoun, Abla; Park, Kihong; Alouini, Mohamed-Slim

    2017-01-01

    Visible light communication (VLC) is an emerging technique that uses light-emitting diodes to combine communication and illumination. It is considered as a promising scheme for indoor wireless communication that can be deployed at reduced costs, while offering high data rate performance. This paper focuses on the design of precoding and receiving schemes for downlink multi-user multiple-input multiple-output VLC systems using angle diversity receivers. Two major concerns need to be considered while solving such a problem. The first one is related to the inter-user interference, basically inherent to our consideration of a multi-user system, while the second results from the users’ mobility, causing imperfect channel estimates. To address both concerns, we propose robust precoding and receiver that solve the max-min SINR problem. The performance of the proposed VLC design is studied under different working conditions, where a significant gain of the proposed robust transceivers over their non-robust counterparts has been observed.

  5. Multi-User Identification-Based Eye-Tracking Algorithm Using Position Estimation

    Directory of Open Access Journals (Sweden)

    Suk-Ju Kang

    2016-12-01

    Full Text Available This paper proposes a new multi-user eye-tracking algorithm using position estimation. Conventional eye-tracking algorithms are typically suitable only for a single user, and thereby cannot be used for a multi-user system. Even though they can be used to track the eyes of multiple users, their detection accuracy is low and they cannot identify multiple users individually. The proposed algorithm solves these problems and enhances the detection accuracy. Specifically, the proposed algorithm adopts a classifier to detect faces for the red, green, and blue (RGB and depth images. Then, it calculates features based on the histogram of the oriented gradient for the detected facial region to identify multiple users, and selects the template that best matches the users from a pre-determined face database. Finally, the proposed algorithm extracts the final eye positions based on anatomical proportions. Simulation results show that the proposed algorithm improved the average F1 score by up to 0.490, compared with benchmark algorithms.

  6. An Efficient and Privacy-Preserving Multiuser Cloud-Based LBS Query Scheme

    Directory of Open Access Journals (Sweden)

    Lu Ou

    2018-01-01

    Full Text Available Location-based services (LBSs are increasingly popular in today’s society. People reveal their location information to LBS providers to obtain personalized services such as map directions, restaurant recommendations, and taxi reservations. Usually, LBS providers offer user privacy protection statement to assure users that their private location information would not be given away. However, many LBSs run on third-party cloud infrastructures. It is challenging to guarantee user location privacy against curious cloud operators while still permitting users to query their own location information data. In this paper, we propose an efficient privacy-preserving cloud-based LBS query scheme for the multiuser setting. We encrypt LBS data and LBS queries with a hybrid encryption mechanism, which can efficiently implement privacy-preserving search over encrypted LBS data and is very suitable for the multiuser setting with secure and effective user enrollment and user revocation. This paper contains security analysis and performance experiments to demonstrate the privacy-preserving properties and efficiency of our proposed scheme.

  7. On low-complexity full-diversity detection of multi-user space-time coding

    KAUST Repository

    Ismail, Amr

    2013-06-01

    The incorporation of multiple input multiple output (MIMO) schemes in recent wireless communication standards paved the way to exploit the newly introduced dimension (i.e. space) to efficiently cancel the interference without requiring additional resources. In this paper, we focus on multiple input multiple ouitput (MIMO) multiple access channel (MAC) case and we answer the question about whether it is possible to suppress the interference in a MIMO MAC channel for completely blind users while achieving full-diversity with a simplified decoder in the affirmative. In fact, this goal can be attained by employing space-time block codes (STBC)s that achive full-diversity under partial interference cancellation (PIC). We derive sufficient conditions for a wide range of STBCs to achieve full-diversity under PIC group decoding with or without successive interference cancellation (SIC). Based on the provided design criteria we derive an upper-bound on the achievable rate for a class of codes. A two-user MIMO MAC interference cancellation scheme is presented and proved to achieve full-diversity under PIC group decoding. We compare our scheme to existing beamforming schemes with full or limit feedback. © 2013 IEEE.

  8. Global data on blindness.

    Science.gov (United States)

    Thylefors, B.; Négrel, A. D.; Pararajasegaram, R.; Dadzie, K. Y.

    1995-01-01

    Globally, it is estimated that there are 38 million persons who are blind. Moreover, a further 110 million people have low vision and are at great risk of becoming blind. The main causes of blindness and low vision are cataract, trachoma, glaucoma, onchocerciasis, and xerophthalmia; however, insufficient data on blindness from causes such as diabetic retinopathy and age-related macular degeneration preclude specific estimations of their global prevalence. The age-specific prevalences of the major causes of blindness that are related to age indicate that the trend will be for an increase in such blindness over the decades to come, unless energetic efforts are made to tackle these problems. More data collected through standardized methodologies, using internationally accepted (ICD-10) definitions, are needed. Data on the incidence of blindness due to common causes would be useful for calculating future trends more precisely. PMID:7704921

  9. Characterizing Student Navigation in Educational Multiuser Virtual Environments: A Case Study Using Data from the River City Project

    Science.gov (United States)

    Dukas, Georg

    2009-01-01

    Though research in emerging technologies is vital to fulfilling their incredible potential for educational applications, it is often fraught with analytic challenges related to large datasets. This thesis explores these challenges in researching multiuser virtual environments (MUVEs). In a MUVE, users assume a persona and traverse a virtual space…

  10. Hybrid Augmented Reality for Participatory Learning: The Hidden Efficacy of Multi-User Game-Based Simulation

    Science.gov (United States)

    Oh, Seungjae; So, Hyo-Jeong; Gaydos, Matthew

    2018-01-01

    The goal for this research is to articulate and test a new hybrid Augmented Reality (AR) environment for conceptual understanding. From the theoretical lens of embodied interaction, we have designed a multi-user participatory simulation called ARfract where visitors in a science museum can learn about complex scientific concepts on the refraction…

  11. Transferring an educational board game to a multi-user mobile learning game to increase shared situational awareness

    NARCIS (Netherlands)

    Klemke, Roland; Kurapati, Shalini; Kolfschoten, Gwendolyn

    2013-01-01

    Klemke, R., Kurapati, S., & Kolfschoten, G. (2013, 6 June). Transferring an educational board game to a multi-user mobile learning game to increase shared situational awareness. In P. Rooney (Ed.), Proceedings of the 3rd Irish Symposium on Game Based Learning (pp. 8-9). Dublin, Ireland. Please see

  12. Transferring an educational board game to a multi-user mobile learning game to increase shared situational awareness

    NARCIS (Netherlands)

    Klemke, Roland; Kurapati, Shalini; Kolfschoten, Gwendolyn

    2013-01-01

    Klemke, R., Kurapati, S., & Kolfschoten, G. (2013, 6 June). Transferring an educational board game to a multi-user mobile learning game to increase shared situational awareness. Presentation at the 3rd Irish Symposium on Game Based Learning, Dublin, Ireland. Please see also

  13. Sum-rate analysis of spectrum sharing spatial multiplexing MIMO systems with zero-forcing and multiuser diversity

    KAUST Repository

    Yang, Liang; Qaraqe, Khalid A.; Serpedin, Erchin; Alouini, Mohamed-Slim

    2013-01-01

    This paper considers a multiuser spectrum sharing (SS) multiple-input multiple-output (MIMO) system with zero-forcing (ZF) operating in a Rayleigh fading environment. We provide an asymptotic sum-rate analysis to investigate the effects of different

  14. Action tagging in a multi-user indoor environment for behavioural analysis purposes.

    Science.gov (United States)

    Guerra, Claudio; Bianchi, Valentina; De Munari, Ilaria; Ciampolini, Paolo

    2015-01-01

    EU population is getting older, so that ICT-based solutions are expected to provide support in the challenges implied by the demographic change. At the University of Parma an AAL (Ambient Assisted Living) system, named CARDEA, has been developed. In this paper a new feature of the system is introduced, in which environmental and personal (i.e., wearable) sensors coexist, providing an accurate picture of the user's activity and needs. Environmental devices may greatly help in performing activity recognition and behavioral analysis tasks. However, in a multi-user environment, this implies the need of attributing environmental sensors outcome to a specific user, i.e., identifying the user when he performs a task detected by an environmental device. We implemented such an "action tagging" feature, based on information fusion, within the CARDEA environment, as an inexpensive, alternative solution to the problematic issue of indoor locationing.

  15. On the Impact of Multi-User Traffic Dynamics on Low Latency Communications

    DEFF Research Database (Denmark)

    Gerardino, Guillermo Andrés Pocovi; Pedersen, Klaus I.; Alvarez, Beatriz Soret

    2016-01-01

    In this paper we study the downlink latency performance in a multi-user cellular network. We use a flexible 5G radio frame structure, where the TTI size is configurable on a per-user basis according to their specific service requirements. Results show that at low system loads using a short TTI (e.......g. 0.25 ms) is an attractive solution to achieve low latency communications (LLC). The main benefits come from the low transmission delay required to transmit the payloads. However, as the load increases, longer TTI configurations with lower relative control overhead (and therefore higher spectral...... efficiency) provide better performance as these better cope with the non-negligible queuing delay. The presented results allow to conclude that support for scheduling with different TTI sizes is important for LLC and should be included in the future 5G....

  16. Multi-User Preemptive Scheduling For Critical Low Latency Communications in 5G Networks

    DEFF Research Database (Denmark)

    Abdul-Mawgood Ali Ali Esswie, Ali; Pedersen, Klaus

    2018-01-01

    5G new radio is envisioned to support three major service classes: enhanced mobile broadband (eMBB), ultrareliable low-latency communications (URLLC), and massive machine type communications. Emerging URLLC services require up to one millisecond of communication latency with 99.999% success...... probability. Though, there is a fundamental trade-off between system spectral efficiency (SE) and achievable latency. This calls for novel scheduling protocols which cross-optimize system performance on user-centric; instead of network-centric basis. In this paper, we develop a joint multi-user preemptive...... scheduling strategy to simultaneously cross-optimize system SE and URLLC latency. At each scheduling opportunity, available URLLC traffic is always given higher priority. When sporadic URLLC traffic appears during a transmission time interval (TTI), proposed scheduler seeks for fitting the URLLC-eMBB traffic...

  17. CGLXTouch: A multi-user multi-touch approach for ultra-high-resolution collaborative workspaces

    KAUST Repository

    Ponto, Kevin

    2011-06-01

    This paper presents an approach for empowering collaborative workspaces through ultra-high resolution tiled display environments concurrently interfaced with multiple multi-touch devices. Multi-touch table devices are supported along with portable multi-touch tablet and phone devices, which can be added to and removed from the system on the fly. Events from these devices are tagged with a device identifier and are synchronized with the distributed display environment, enabling multi-user support. As many portable devices are not equipped to render content directly, a remotely scene is streamed in. The presented approach scales for large numbers of devices, providing access to a multitude of hands-on techniques for collaborative data analysis. © 2011 Elsevier B.V. All rights reserved.

  18. Optimal Multiuser Zero Forcing with Per-Antenna Power Constraints for Network MIMO Coordination

    Directory of Open Access Journals (Sweden)

    Kaviani Saeed

    2011-01-01

    Full Text Available We consider a multicell multiple-input multiple-output (MIMO coordinated downlink transmission, also known as network MIMO, under per-antenna power constraints. We investigate a simple multiuser zero-forcing (ZF linear precoding technique known as block diagonalization (BD for network MIMO. The optimal form of BD with per-antenna power constraints is proposed. It involves a novel approach of optimizing the precoding matrices over the entire null space of other users' transmissions. An iterative gradient descent method is derived by solving the dual of the throughput maximization problem, which finds the optimal precoding matrices globally and efficiently. The comprehensive simulations illustrate several network MIMO coordination advantages when the optimal BD scheme is used. Its achievable throughput is compared with the capacity region obtained through the recently established duality concept under per-antenna power constraints.

  19. A Multi-Usable Cloud Service Platform: A Case Study on Improved Development Pace and Efficiency

    Directory of Open Access Journals (Sweden)

    John Lindström

    2018-02-01

    Full Text Available The case study, spanning three contexts, concerns a multi-usable cloud service platform for big data collection and analytics and how the development pace and efficiency of it has been improved by 50–75% by using the Arrowhead framework and changing development processes/practices. Furthermore, additional results captured during the case study are related to technology, competencies and skills, organization, management, infrastructure, and service and support. A conclusion is that when offering a complex offer such as an Industrial Product-Service System, comprising sensors, hardware, communications, software, cloud service platform, etc., it is necessary that the technology, business model, business setup, and organization all go hand in hand during the development and later operation, as all ‘components’ are required for a successful result.

  20. Proof-of-Concept System for Opportunistic Spectrum Access in Multi-user Decentralized Networks

    Directory of Open Access Journals (Sweden)

    Sumit J. Darak

    2016-09-01

    Full Text Available Poor utilization of an electromagnetic spectrum and ever increasing demand for spectrum have led to surge of interests in opportunistic spectrum access (OSA based paradigms like cognitive radio and unlicensed LTE. In OSA for decentralized networks, frequency band selection from wideband spectrum is a challenging task since secondary users (SUs do not share any information with each other. In this paper, a new decision making policy (DMP has been proposed for OSA in the multi-user decentralized networks. First contribution is an accurate characterization of frequency bands using Bayes-UCB algorithm. Then, a novel SU orthogonization scheme using Bayes-UCB algorithm is proposed replacing randomization based scheme. At the end, USRP testbed has been developed for analyzing the performance of DMPs using real radio signals. Experimental results show that the proposed DMP offers significant improvement in spectrum utilization, fewer subband switching and collisions compared to other DMPs.

  1. Coding Across Multicodes and Time in CDMA Systems Employing MMSE Multiuser Detector

    Directory of Open Access Journals (Sweden)

    Park Jeongsoon

    2004-01-01

    Full Text Available When combining a multicode CDMA system with convolutional coding, two methods have been considered in the literature. In one method, coding is across time in each multicode channel while in the other the coding is across both multicodes and time. In this paper, a performance/complexity analysis of decoding metrics and trellis structures for the two schemes is carried out. It is shown that the latter scheme can exploit the multicode diversity inherent in convolutionally coded direct sequence code division multiple access (DS-CDMA systems which employ minimum mean squared error (MMSE multiuser detectors. In particular, when the MMSE detector provides sufficiently different signal-to-interference ratios (SIRs for the multicode channels, coding across multicodes and time can obtain significant performance gain over coding across time, with nearly the same decoding complexity.

  2. Performance improvement of per-user threshold based multiuser switched scheduling system

    KAUST Repository

    Nam, Haewoon

    2013-01-01

    SUMMARY This letter proposes a multiuser switched scheduling scheme with per-user threshold and post user selection and provides a generic analytical framework for determining the optimal feedback thresholds. The proposed scheme applies an individual feedback threshold for each user rather than a single common threshold for all users to achieve some capacity gain due to the flexibility of threshold selection as well as a lower scheduling outage probability. In addition, since scheduling outage may occur with a non-negligible probability, the proposed scheme employs post user selection in order to further improve the ergodic capacity, where the user with the highest potential for a higher channel quality than other users is selected. Numerical and simulation results show that the capacity gain by post user selection is significant when random sequence is used. Copyright © 2013 The Institute of Electronics, Information and Communication Engineers.

  3. Developing an effective adaptive monitoring network to support integrated coastal management in a multiuser nature reserve

    Directory of Open Access Journals (Sweden)

    Pim Vugteveen

    2015-03-01

    Full Text Available We elaborate the necessary conceptual and strategic elements for developing an effective adaptive monitoring network to support Integrated Coastal Management (ICM in a multiuser nature reserve in the Dutch Wadden Sea Region. We discuss quality criteria and enabling actions essential to accomplish and sustain monitoring excellence to support ICM. The Wadden Sea Long-Term Ecosystem Research project (WaLTER was initiated to develop an adaptive monitoring network and online data portal to better understand and support ICM in the Dutch Wadden Sea Region. Our comprehensive approach integrates ecological and socioeconomic data and links research-driven and policy-driven monitoring for system analysis using indicators of pressures, state, benefits, and responses. The approach and concepts we elaborated are transferable to other coastal regions to accomplish ICM in complex social-ecological systems in which scientists, multisectoral stakeholders, resource managers, and governmental representatives seek to balance long-term ecological, economic, and social objectives within natural limits.

  4. Specialized, multi-user computer facility for the high-speed, interactive processing of experimental data

    International Nuclear Information System (INIS)

    Maples, C.C.

    1979-01-01

    A proposal has been made to develop a specialized computer facility specifically designed to deal with the problems associated with the reduction and analysis of experimental data. Such a facility would provide a highly interactive, graphics-oriented, multi-user environment capable of handling relatively large data bases for each user. By conceptually separating the general problem of data analysis into two parts, cyclic batch calculations and real-time interaction, a multi-level, parallel processing framework may be used to achieve high-speed data processing. In principle such a system should be able to process a mag tape equivalent of data, through typical transformations and correlations, in under 30 sec. The throughput for such a facility, assuming five users simultaneously reducing data, is estimated to be 2 to 3 times greater than is possible, for example, on a CDC7600

  5. Performance Analysis of Diversity-Controlled Multi-User Superposition Transmission for 5G Wireless Networks.

    Science.gov (United States)

    Yeom, Jeong Seon; Chu, Eunmi; Jung, Bang Chul; Jin, Hu

    2018-02-10

    In this paper, we propose a novel low-complexity multi-user superposition transmission (MUST) technique for 5G downlink networks, which allows multiple cell-edge users to be multiplexed with a single cell-center user. We call the proposed technique diversity-controlled MUST technique since the cell-center user enjoys the frequency diversity effect via signal repetition over multiple orthogonal frequency division multiplexing (OFDM) sub-carriers. We assume that a base station is equipped with a single antenna but users are equipped with multiple antennas. In addition, we assume that the quadrature phase shift keying (QPSK) modulation is used for users. We mathematically analyze the bit error rate (BER) of both cell-edge users and cell-center users, which is the first theoretical result in the literature to the best of our knowledge. The mathematical analysis is validated through extensive link-level simulations.

  6. Following the actors and avatars of massively multi-user online role-playing games

    DEFF Research Database (Denmark)

    Jensen, Sisse Siggaard

    2007-01-01

    held in high esteem by a group, or guild, of avatars and actors, these are activities, which may be conceived of as being complex, reflective practices. To become a skilled, professional, high-level avatar is hard work, it may take months, and only then, can the avatar perform without the many......’ conceptions of the virtual worlds, 2) their choices and constructions of mediating avatars, 3) the diversity of social interactions, 4) the constructions of self experienced and expressed while reflecting on action and communication, and 5) the interplay between the virtual worlds and the actors’ life worlds......In the massively multi-user online role-playing games of e.g. EverQuest I & II and the World of Warcraft, millions of actors inhabit and create new places and spaces for communication and social interaction (Castranova 2001, Gee, 2003, Goffman 1974/86, Jensen 2006a, Qvortrup 2001, 2002). Some...

  7. AdaM: Adapting Multi-User Interfaces for Collaborative Environments in Real-Time

    DEFF Research Database (Denmark)

    Park, Seonwook; Gebhardt, Christoph; Rädle, Roman

    2018-01-01

    and rule-based solutions are tedious to create and do not scale to larger problems nor do they adapt to dynamic changes, such as users leaving or joining an activity. In this paper, we cast the problem of UI distribution as an assignment problem and propose to solve it using combinatorial optimization. We...... present a mixed integer programming formulation which allows real-time applications in dynamically changing collaborative settings. It optimizes the allocation of UI elements based on device capabilities, user roles, preferences, and access rights. We present a proof-of-concept designer-in-the-loop tool......Developing cross-device multi-user interfaces (UIs) is a challenging problem. There are numerous ways in which content and interactivity can be distributed. However, good solutions must consider multiple users, their roles, their preferences and access rights, as well as device capabilities. Manual...

  8. Specialized, multi-user computer facility for the high-speed, interactive processing of experimental data

    International Nuclear Information System (INIS)

    Maples, C.C.

    1979-05-01

    A proposal has been made at LBL to develop a specialized computer facility specifically designed to deal with the problems associated with the reduction and analysis of experimental data. Such a facility would provide a highly interactive, graphics-oriented, multi-user environment capable of handling relatively large data bases for each user. By conceptually separating the general problem of data analysis into two parts, cyclic batch calculations and real-time interaction, a multilevel, parallel processing framework may be used to achieve high-speed data processing. In principle such a system should be able to process a mag tape equivalent of data through typical transformations and correlations in under 30 s. The throughput for such a facility, for five users simultaneously reducing data, is estimated to be 2 to 3 times greater than is possible, for example, on a CDC7600. 3 figures

  9. A game-theoretical pricing mechanism for multiuser rate allocation for video over WiMAX

    Science.gov (United States)

    Chen, Chao-An; Lo, Chi-Wen; Lin, Chia-Wen; Chen, Yung-Chang

    2010-07-01

    In multiuser rate allocation in a wireless network, strategic users can bias the rate allocation by misrepresenting their bandwidth demands to a base station, leading to an unfair allocation. Game-theoretical approaches have been proposed to address the unfair allocation problems caused by the strategic users. However, existing approaches rely on a timeconsuming iterative negotiation process. Besides, they cannot completely prevent unfair allocations caused by inconsistent strategic behaviors. To address these problems, we propose a Search Based Pricing Mechanism to reduce the communication time and to capture a user's strategic behavior. Our simulation results show that the proposed method significantly reduce the communication time as well as converges stably to an optimal allocation.

  10. Performance of an opportunistic multi-user cognitive network with multiple primary users

    KAUST Repository

    Khan, Fahd Ahmed

    2014-04-01

    Consider a multi-user underlay cognitive network where multiple cognitive users, having limited peak transmit power, concurrently share the spectrum with a primary network with multiple users. The channel between the secondary network is assumed to have independent but not identical Nakagami-m fading. The interference channel between the secondary users and the primary users is assumed to have Rayleigh fading. The uplink scenario is considered where a single secondary user is selected for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the momentgenerating function, outage performance and the symbol-error-rate performance are derived. The outage performance is also studied in the asymptotic regimes and the generalized diversity gain of this scheduling scheme is derived. Numerical results corroborate the derived analytical results.

  11. SWIPT in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2017-02-09

    In this paper, we consider a multiuser multiple- input multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting relays and multiple destinations. Since the end-to-end sum rate maximization problem is intractable, we tackle a simplified problem where we maximize the sum of the harvested energy at the relays, we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relay- destination channels. The interference mitigation at the destinations is managed in two ways: either to fix the interference covariance matrices at the destination and update them at each iteration until convergence, or to cancel the interference using an algorithm similar to the BD method. We provide numerical results to show the relevance of our proposed solution.

  12. Low Complexity Tree Searching-Based Iterative Precoding Techniques for Multiuser MIMO Broadcast Channel

    Science.gov (United States)

    Cha, Jongsub; Park, Kyungho; Kang, Joonhyuk; Park, Hyuncheol

    In this letter, we propose two computationally efficient precoding algorithms that achieve near-ML performance for multiuser MIMO downlink. The proposed algorithms perform tree expansion after lattice reduction. The first full expansion is tried by selecting the first level node with a minimum metric, constituting a reference metric. To find an optimal sequence, they iteratively visit each node and terminate the expansion by comparing node metrics with the calculated reference metric. By doing this, they significantly reduce the number of undesirable node visit. Monte-Carlo simulations show that both proposed algorithms yield near-ML performance with considerable reduction in complexity compared with that of the conventional schemes such as sphere encoding.

  13. Performance Analysis of Free-Space Optical Communication Systems With Multiuser Diversity Over Atmospheric Turbulence Channels

    KAUST Repository

    Yang, Liang

    2014-04-01

    Free-space optical (FSO) communication has become a cost-effective method to provide high data rates. However, the turbulence-induced fading limits its application to short-range applications. To address this, we propose a multiuser diversity (MD) FSO scheme in which the Nth best user is selected and the channel fluctuations can be effectively exploited to produce a selection diversity gain. More specifically, we first present the statistics analysis for the considered system over both weak and strong atmospheric turbulence channels. Based on these statistics, the outage probability, bit-error rate performance, average capacity, diversity order, and coverage are analyzed. Results show that the diversity order for the gamma-gamma fading is N min{α, β}/2, where N is the number of users, and α and β are the channel fading parameters related to the effective atmospheric conditions of the link.

  14. The LLNL Multiuser Tandem Laboratory computer-controlled radiation monitoring system

    International Nuclear Information System (INIS)

    Homann, S.G.

    1992-01-01

    The Physics Department of the Lawrence Livermore National Laboratory (LLNL) recently constructed a Multiuser Tandem Laboratory (MTL) to perform a variety of basic and applied measurement programs. The laboratory and its research equipment were constructed with support from a consortium of LLNL Divisions, Sandia National Laboratories Livermore, and the University of California. Primary design goals for the facility were inexpensive construction and operation, high beam quality at a large number of experimental stations, and versatility in adapting to new experimental needs. To accomplish these goals, our main design decisions were to place the accelerator in an unshielded structure, to make use of reconfigured cyclotrons as effective switching magnets, and to rely on computer control systems for both radiological protection and highly reproducible and well-characterized accelerator operation. This paper addresses the radiological control computer system

  15. Postictal blindness in adults.

    OpenAIRE

    Sadeh, M; Goldhammer, Y; Kuritsky, A

    1983-01-01

    Cortical blindness following grand mal seizures occurred in five adult patients. The causes of seizures included idiopathic epilepsy, vascular accident, brain cyst, acute encephalitis and chronic encephalitis. Blindness was permanent in one patients, but the others recovered within several days. Since most of the patients were either unaware of or denied their blindness, it is possible that this event often goes unrecognised. Cerebral hypoxia is considered the most likely mechanism.

  16. Non-sectarian scenario experiments in socio-ecological knowledge building for multi-use marine environments: Insights from New Zealand's Marine Futures project

    KAUST Repository

    Le Heron, Richard; Lewis, Nick; Fisher, Karen; Thrush, Simon; Lundquist, Carolyn; Hewitt, Judi; Ellis, Joanne

    2016-01-01

    of trust and collective organisation, showing the importance of values-means-ends pathways, developing facilitative legislation to enable initiatives, and the utility of the NSSEs in informing new governance and management directions in multi-use marine

  17. Effect of RF Interference on the Security-Reliability Trade-off Analysis of Multiuser Mixed RF/FSO Relay Networks with Power Allocation

    KAUST Repository

    Abd El-Malek, Ahmed H.; Salhab, Anas; Zummo, Salam; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, the impact of radio frequency (RF) cochannel interference (CCI) on the performance of multiuser mixed RF/free-space optical (FSO) relay network with opportunistic user scheduling under eavesdropping attack is studied. The considered

  18. Blind Analysis in Particle Physics

    International Nuclear Information System (INIS)

    Roodman, A

    2003-01-01

    A review of the blind analysis technique, as used in particle physics measurements, is presented. The history of blind analyses in physics is briefly discussed. Next the dangers of and the advantages of a blind analysis are described. Three distinct kinds of blind analysis in particle physics are presented in detail. Finally, the BABAR collaboration's experience with the blind analysis technique is discussed

  19. Blinding for unanticipated signatures

    NARCIS (Netherlands)

    D. Chaum (David)

    1987-01-01

    textabstractPreviously known blind signature systems require an amount of computation at least proportional to the number of signature types, and also that the number of such types be fixed in advance. These requirements are not practical in some applications. Here, a new blind signature technique

  20. "Color-Blind" Racism.

    Science.gov (United States)

    Carr, Leslie G.

    Examining race relations in the United States from a historical perspective, this book explains how the constitution is racist and how color blindness is actually a racist ideology. It is argued that Justice Harlan, in his dissenting opinion in Plessy v. Ferguson, meant that the constitution and the law must remain blind to the existence of race…

  1. Models for the blind

    DEFF Research Database (Denmark)

    Olsén, Jan-Eric

    2014-01-01

    person to touch them in their historical context. And yet these objects are all about touch, from the concrete act of touching something to the norms that assigned touch a specific pedagogical role in nineteenth-century blind schools. The aim of this article is twofold. First, I provide a historical......When displayed in museum cabinets, tactile objects that were once used in the education of blind and visually impaired people, appear to us, sighted visitors, as anything but tactile. We cannot touch them due to museum policies and we can hardly imagine what it would have been like for a blind...... background to the tactile objects of the blind. When did they appear as a specific category of pedagogical aid and how did they help determine the relation between blindness, vision, and touch? Second, I address the tactile objects from the point of view of empirical sources and historical evidence. Material...

  2. Making Information Available to Partially Sighted and Blind Clients.

    Science.gov (United States)

    Long, C. A.

    1993-01-01

    Provides an empirical review of problems facing library users with visual impairments using computers, and reviews some of the technology that can help alleviate these problems. Highlights include software; GUI (Graphical User Interfaces); advising and training; library automation; and appendices that list further sources of relevant information.…

  3. Partially blind instantly decodable network codes for lossy feedback environment

    KAUST Repository

    Sorour, Sameh; Douik, Ahmed S.; Valaee, Shahrokh; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2014-01-01

    an expression for the expected decoding delay increment for any arbitrary transmission. This expression is then used to find the optimal policy that reduces the decoding delay in such lossy feedback environment. Results show that our proposed solutions both

  4. Blinded by Irrelevance: Pure Irrelevance Induced "Blindness"

    Science.gov (United States)

    Eitam, Baruch; Yeshurun, Yaffa; Hassan, Kinneret

    2013-01-01

    To what degree does our representation of the immediate world depend solely on its relevance to what we are currently doing? We examined whether relevance per se can cause "blindness," even when there is no resource limitation. In a novel paradigm, people looked at a colored circle surrounded by a differently colored ring--the task relevance of…

  5. PHYSIOTHERAPY OF BLIND AND LOW VISION INDIVIDUALS

    Directory of Open Access Journals (Sweden)

    Alenka Tatjana Sterle

    2002-12-01

    Full Text Available Background. The authors present a preventive physiotherapy programme intended to improve the well-being of persons who have been blind or visually impaired since birth or experience partial or complete loss of vision later in life as a result of injury or disease.Methods. Different methods and techniques of physiotherapy, kinesitherapy and relaxation used in the rehabilitation of visually impaired persons are described.Results. The goals of timely physical treatment are to avoid unnecessary problems, such as improper posture, tension of the entire body, face and eyes, and deterioration of facial expression, that often accompany partial or complete loss of vision. Regular training improves functional skills, restores the skills that have been lost, and prevents the development of defects and consequent disorders of the locomotor apparatus.Conclusions. It is very difficult to change the life style and habits of blind and visually imapired persons. Especially elderly people who experience complete or partial loss of vision later in their lives are often left to their fate. Therefore blind and visually impaired persons of all age groups should be enrolled in a suitable rehabilitation programme that will improve the quality of their life.

  6. Alteration and Implementation of the CP/M-86 Operating System for a Multi-User Environment.

    Science.gov (United States)

    1982-12-01

    THE CP/M-86 OPERATING SYSTEM FOR A MULTI-USER ENVIRONMENT by Thomas V. Almquist and David S. Stevens C-, December 1982 ,LU Thesis Advisor : U. R. Kodres...tool$ 044, robo O0eA 6^900091 Approved for public release; distribution unlimited Alteration and Implementation of the CP/M-86 Operating System for a...SCIENCE IN COMPUTER SCIENCE from the NAVAL POSTGRADUATE SCHOOL December 1982 Authors: Approved by: ..... .. . . . . . . . . Thesis Advisor Second

  7. A Smart Infrared Microcontroller-Based Blind Guidance System

    Directory of Open Access Journals (Sweden)

    Amjed S. Al-Fahoum

    2013-01-01

    Full Text Available Blindness is a state of lacking the visual perception due to physiological or neurological factors. The partial blindness represents the lack of integration in the growth of the optic nerve or visual centre of the eye, and total blindness is the full absence of the visual light perception. In this work, a simple, cheap, friendly user, smart blind guidance system is designed and implemented to improve the mobility of both blind and visually impaired people in a specific area. The proposed work includes a wearable equipment consists of head hat and mini hand stick to help the blind person to navigate alone safely and to avoid any obstacles that may be encountered, whether fixed or mobile, to prevent any possible accident. The main component of this system is the infrared sensor which is used to scan a predetermined area around blind by emitting-reflecting waves. The reflected signals received from the barrier objects are used as inputs to PIC microcontroller. The microcontroller is then used to determine the direction and distance of the objects around the blind. It also controls the peripheral components that alert the user about obstacle's shape, material, and direction. The implemented system is cheap, fast, and easy to use and an innovative affordable solution to blind and visually impaired people in third world countries.

  8. The blind hens’ challenge

    DEFF Research Database (Denmark)

    Sandøe, Peter; Hocking, Paul M.; Forkman, Björn

    2014-01-01

    about breeding blind hens. But we also argue that alternative views, which (for example) claim that it is important to respect the telos or rights of an animal, do not offer a more convincing solution to questions raised by the possibility of disenhancing animals for their own benefit.......Animal ethicists have recently debated the ethical questions raised by disenhancing animals to improve their welfare. Here, we focus on the particular case of breeding blind hens for commercial egg-laying systems, in order to benefit their welfare. Many people find breeding blind hens intuitively...

  9. Blind loop syndrome

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001146.htm Blind loop syndrome To use the sharing features on ... Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David ...

  10. Non-orthogonal transmission in multi-user systems with Grassmannian beamforming

    KAUST Repository

    Xia, Minghua

    2011-06-01

    Aiming to achieve the sum-rate capacity in multiuser multi-input multi-output (MIMO) channels with N t antennas implemented at the transmitter, opportunistic beamforming (OBF) generates N t orthonormal beams and serves N t users during each transmission, which results in high scheduling delay over the users, especially in densely populated wireless networks. Non-orthogonal OBF with more than N t transmit beams can be exploited to serve more users simultaneously and further decreases scheduling delay. However, the inter-beam interference will inevitably deteriorate the sum-rate. Therefore, there is a tradeoff between the sum-rate and the increasing number of transmit beams. In this context, the sum-rate of non-orthogonal OBF with N > N t beams are studied, where the transmitter is based on the Grassmannian beamforming. Our results show that non-orthogonal OBF is an interference-limited system. Moreover, when the inter-beam interference reaches its minimum for fixed N t and N, the sum-rate scales as N ln (N/N-N t) and it decreases monotonically with N for fixed N t. Numerical results corroborate the accuracy of our analyses. © 2011 IEEE.

  11. Efficiently Multi-User Searchable Encryption Scheme with Attribute Revocation and Grant for Cloud Storage.

    Science.gov (United States)

    Wang, Shangping; Zhang, Xiaoxue; Zhang, Yaling

    2016-01-01

    Cipher-policy attribute-based encryption (CP-ABE) focus on the problem of access control, and keyword-based searchable encryption scheme focus on the problem of finding the files that the user interested in the cloud storage quickly. To design a searchable and attribute-based encryption scheme is a new challenge. In this paper, we propose an efficiently multi-user searchable attribute-based encryption scheme with attribute revocation and grant for cloud storage. In the new scheme the attribute revocation and grant processes of users are delegated to proxy server. Our scheme supports multi attribute are revoked and granted simultaneously. Moreover, the keyword searchable function is achieved in our proposed scheme. The security of our proposed scheme is reduced to the bilinear Diffie-Hellman (BDH) assumption. Furthermore, the scheme is proven to be secure under the security model of indistinguishability against selective ciphertext-policy and chosen plaintext attack (IND-sCP-CPA). And our scheme is also of semantic security under indistinguishability against chosen keyword attack (IND-CKA) in the random oracle model.

  12. Dynamic Subcarrier Allocation for Real-Time Traffic over Multiuser OFDM Systems

    Directory of Open Access Journals (Sweden)

    Li VictorOK

    2009-01-01

    Full Text Available A dynamic resource allocation algorithm to satisfy the packet delay requirements for real-time services, while maximizing the system capacity in multiuser orthogonal frequency division multiplexing (OFDM systems is introduced. Our proposed cross-layer algorithm, called Dynamic Subcarrier Allocation algorithm for Real-time Traffic (DSA-RT, consists of two interactive components. In the medium access control (MAC layer, the users' expected transmission rates in terms of the number of subcarriers per symbol and their corresponding transmission priorities are evaluated. With the above MAC-layer information and the detected subcarriers' channel gains, in the physical (PHY layer, a modified Kuhn-Munkres algorithm is developed to minimize the system power for a certain subcarrier allocation, then a PHY-layer resource allocation scheme is proposed to optimally allocate the subcarriers under the system signal-to-noise ratio (SNR and power constraints. In a system where the number of mobile users changes dynamically, our developed MAC-layer access control and removal schemes can guarantee the quality of service (QoS of the existing users in the system and fully utilize the bandwidth resource. The numerical results show that DSA-RT significantly improves the system performance in terms of the bandwidth efficiency and delay performance for real-time services.

  13. Single-user MIMO versus multi-user MIMO in distributed antenna systems with limited feedback

    Science.gov (United States)

    Schwarz, Stefan; Heath, Robert W.; Rupp, Markus

    2013-12-01

    This article investigates the performance of cellular networks employing distributed antennas in addition to the central antennas of the base station. Distributed antennas are likely to be implemented using remote radio units, which is enabled by a low latency and high bandwidth dedicated link to the base station. This facilitates coherent transmission from potentially all available antennas at the same time. Such distributed antenna system (DAS) is an effective way to deal with path loss and large-scale fading in cellular systems. DAS can apply precoding across multiple transmission points to implement single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) transmission. The throughput performance of various SU-MIMO and MU-MIMO transmission strategies is investigated in this article, employing a Long-Term evolution (LTE) standard compliant simulation framework. The previously theoretically established cell-capacity improvement of MU-MIMO in comparison to SU-MIMO in DASs is confirmed under the practical constraints imposed by the LTE standard, even under the assumption of imperfect channel state information (CSI) at the base station. Because practical systems will use quantized feedback, the performance of different CSI feedback algorithms for DASs is investigated. It is shown that significant gains in the CSI quantization accuracy and in the throughput of especially MU-MIMO systems can be achieved with relatively simple quantization codebook constructions that exploit the available temporal correlation and channel gain differences.

  14. A multi-user selective undo/redo approach for collaborative CAD systems

    Directory of Open Access Journals (Sweden)

    Yuan Cheng

    2014-04-01

    Full Text Available The engineering design process is a creative process, and the designers must repeatedly apply Undo/Redo operations to modify CAD models to explore new solutions. Undo/Redo has become one of most important functions in interactive graphics and CAD systems. Undo/Redo in a collaborative CAD system is also very helpful for collaborative awareness among a group of cooperative designers to eliminate misunderstanding and to recover from design error. However, Undo/Redo in a collaborative CAD system is much more complicated. This is because a single erroneous operation is propagated to other remote sites, and operations are interleaved at different sites. This paper presents a multi-user selective Undo/Redo approach in full distributed collaborative CAD systems. We use site ID and State Vectors to locate the Undo/Redo target at each site. By analyzing the composition of the complex CAD model, a tree-like structure called Feature Combination Hierarchy is presented to describe the decomposition of a CAD model. Based on this structure, the dependency relationship among features is clarified. B-Rep re-evaluation is simplified with the assistance of the Feature Combination Hierarchy. It can be proven that the proposed Undo/Redo approach satisfies the intention preservation and consistency maintenance correctness criteria for collaborative systems.

  15. Diversity-Multiplexing-Nulling Trade-Off Analysis of Multiuser MIMO System for Intercell Interference Coordination

    Directory of Open Access Journals (Sweden)

    Jinwoo Kim

    2017-01-01

    Full Text Available A fundamental performance trade-off of multicell multiuser multiple-input multiple-output (MU-MIMO systems is explored for achieving intercell and intracell interference-free conditions. In particular, we analyze the three-dimensional diversity-multiplexing-nulling trade-off (DMNT among the diversity order (i.e., the slope of the error performance curve, multiplexing order (i.e., the number of users that are simultaneously served by MU-MIMO, and nulling order (i.e., the number of users with zero interference in a victim cell. This trade-off quantifies the performance of MU-MIMO in terms of its diversity and multiplexing order, while nulling the intercell interference toward the victim cell in the neighbor. First, we design a precoding matrix to mitigate both intercell and intracell interference for a linear precoding-based MU-MIMO system. Then, the trade-off relationship is obtained by analyzing the distribution of the signal-to-noise ratio (SNR at the user terminals. Furthermore, we demonstrate how DMNT can be applied to estimate the long-term throughput for each mobile station, which allows for determining the optimal number of multiplexing order and throughput loss due to the interference nulling.

  16. Feedback Reduction in Broadcast and two Hop Multiuser Networks: A Compressed Sensing Approach

    KAUST Repository

    Shibli, Hussain J.

    2013-05-21

    In multiuser wireless networks, the base stations (BSs) rely on the channel state information (CSI) of the users to in order to perform user scheduling and downlink transmission. While the downlink channels can be easily estimated at all user terminals via a single broadcast, several key challenges are faced during uplink (feedback) transmission. Firstly, the noisy and fading feedback channels are usually unknown at the base station, and therefore, channel training is usually required from all users. Secondly, the amount of air-time required for feedback transmission grows linearly with the number of users. This domination of the network resources by feedback information leads to increased scheduling delay and outdated CSI at the BS. In this thesis, we tackle the above challenges and propose feedback reduction algorithms based on the theory of compressive sensing (CS). The proposed algorithms encompass both single and dual hop wireless networks, and; i) permit the BS to obtain CSI with acceptable recovery guarantees under substantially reduced feedback overhead, ii) are agnostic to the statistics of the feedback channels, and iii) utilize the apriori statistics of the additive noise to identify strong users. Numerical results show that the proposed algorithms are able to reduce the feedback overhead, improve detection at the BS, and achieve a sum-rate close to that obtained by noiseless dedicated feedback algorithms.

  17. Block compressed sensing for feedback reduction in relay-aided multiuser full duplex networks

    KAUST Repository

    Elkhalil, Khalil

    2016-08-11

    Opportunistic user selection is a simple technique that exploits the spatial diversity in multiuser relay-aided networks. Nonetheless, channel state information (CSI) from all users (and cooperating relays) is generally required at a central node in order to make selection decisions. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the presence of a full-duplex cooperating relay corrupts the fed back CSI by additive noise and the relay\\'s loop (or self) interference. This could lead to transmission outages if user selection is based on inaccurate feedback information. In this paper, we propose an opportunistic full-duplex feedback algorithm that tackles the above challenges. We cast the problem of joint user signal-to-noise ratio (SNR) and the relay loop interference estimation at the base-station as a block sparse signal recovery problem in compressive sensing (CS). Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated. Numerical results show that the proposed technique drastically reduces the feedback overhead and achieves a rate close to that obtained by techniques that require dedicated error-free feedback from all users. Numerical results also show that there is a trade-off between the feedback interference and load, and for short coherence intervals, full-duplex feedback achieves higher throughput when compared to interference-free (half-duplex) feedback. © 2016 IEEE.

  18. On the Feedback Reduction of Relay Multiuser Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil

    2016-01-29

    This paper presents a comprehensive performance analysis of full-duplex multiuser relay networks employing opportunistic scheduling with noisy and compressive feedback. Specifically, two feedback techniques based on compressive sensing (CS) theory are introduced and their effect on the system performance is analyzed. The problem of joint user identity and signal-tonoise ratio (SNR) estimation at the base-station is casted as a block sparse signal recovery problem in CS. Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated using the best linear unbiased estimator (BLUE). To minimize the effect of feedback noise on the estimated SNRs, a back-off strategy that optimally backs-off on the noisy estimated SNRs is introduced, and the error covariance matrix of the noise after CS recovery is derived. Finally, closed-form expressions for the end-to-end SNRs of the system are derived. Numerical results show that the proposed techniques drastically reduce the feedback air-time and achieve a rate close to that obtained by scheduling techniques that require dedicated error-free feedback from all network users. Key findings of this paper suggest that the choice of half-duplex or full-duplex SNR feedback is dependent on the channel coherence interval, and on low coherence intervals, full-duplex feedback is superior to the interference-free half-duplex feedback.

  19. Performance of fading multi-user diversity for underlay cognitive networksy

    KAUST Repository

    Khan, Fahd Ahmed

    2013-05-01

    Having multiple secondary users (SUs) can be exploited to achieve multiuser diversity and improve the throughput of the underlay secondary network. In the cognitive setting, satisfying the interference constraint is essential, and thus, a scheduling scheme is considered where some SUs are preselected based on the low interference power. From this subset, the SU that yields the highest throughput is selected for transmission. This scheduling scheme helps to lower the interference power while giving good throughput. For an independent but not identically distributed Nakagami-m fading channel, we obtain exact closed-form expressions of the capacity of this scheduling scheme. Furthermore, the scheduling time of SUs is characterized and closed-form expressions for the mean time after which a SU is selected for transmission are obtained. Numerical simulations are performed to corroborate the derived analytical results. Our results show that at low interference threshold, increasing transmit power of the SUs is not beneficial and results in reduced capacity. Furthermore, the channel idle time (i.e. time that no user is utilizing the channel) reduces with increasing the number of SUs. © 2013 IEEE.

  20. Hybrid precoding based on matrix-adaptive method for multiuser large-scale antenna arrays.

    Directory of Open Access Journals (Sweden)

    Yongpan Feng

    Full Text Available Massive multiple-input multiple-output (MIMO is envisioned to offer a considerable improvement in capacity, but it has a high cost and the radio frequency (RF chain components have a high power consumption at high frequency. To address this problem, a hybrid analog and digital precoding scheme has been studied recently, which restricts the number of RF chains to far less than the number of antenna elements. In this paper, we consider the downlink communication of a massive multiuser multiple-input single-output (MU-MISO system and propose an iterative hybrid precoding algorithm to approach the capacity performance of the traditional full digital precoding scheme. We aim to attain a large baseband gain by zero-forcing (ZF digital precoding on the equivalent channel and then minimize the total power to obtain the optimal RF precoder. Simulation results show that the proposed method can approach the performance of the conventional fully digital precoding with a low computational complexity.

  1. Prototyping Tool for Web-Based Multiuser Online Role-Playing Game

    Science.gov (United States)

    Okamoto, Shusuke; Kamada, Masaru; Yonekura, Tatsuhiro

    This letter proposes a prototyping tool for Web-based Multiuser Online Role-Playing Game (MORPG). The design goal is to make this tool simple and powerful. The tool is comprised of a GUI editor, a translator and a runtime environment. The GUI editor is used to edit state-transition diagrams, each of which defines the behavior of the fictional characters. The state-transition diagrams are translated into C program codes, which plays the role of a game engine in RPG system. The runtime environment includes PHP, JavaScript with Ajax and HTML. So the prototype system can be played on the usual Web browser, such as Fire-fox, Safari and IE. On a click or key press by a player, the Web browser sends it to the Web server to reflect its consequence on the screens which other players are looking at. Prospected users of this tool include programming novices and schoolchildren. The knowledge or skill of any specific programming languages is not required to create state-transition diagrams. Its structure is not only suitable for the definition of a character behavior but also intuitive to help novices understand. Therefore, the users can easily create Web-based MORPG system with the tool.

  2. Multi-Use seismic stations offer strong deterrent to clandestine nuclear weapons testing

    Science.gov (United States)

    Hennet, C. B.; Van der Vink, G. E.; Richards, P. G.; Adushkin, V. V.; Kopnichev, Y. F.; Geary, R.

    As the United States and other nations push for the signing of a Comprehensive Test Ban Treaty, representatives are meeting in Geneva this year to develop an International Seismic Monitoring System to verify compliance with the treaty's restrictions. In addition to the official monitoring system, regional networks developed for earthquake studies and basic research can provide a strong deterrent against clandestine testing. The recent release of information by the U.S. Department of Energy (DoE) on previously unannounced nuclear tests provides an opportunity to assess the ability of multi-use seismic networks to help monitor nuclear testing across the globe.Here we look at the extent to which the formerly unannounced tests were recorded and identified on the basis of publicly available seismographic data recorded by five seismic networks. The data were recorded by networks in southern Nevada and northern California at stations less than 1500 km from the Nevada Test Site (NTS), and two networks in the former Soviet Union at stations farther than 1500 km from the NTS.

  3. Performance of Cross-layer Design with Multiple Outdated Estimates in Multiuser MIMO System

    Directory of Open Access Journals (Sweden)

    X. Yu

    2014-09-01

    Full Text Available By combining adaptive modulation (AM and automatic repeat request (ARQ protocol as well as user scheduling, the cross-layer design scheme of multiuser MIMO system with imperfect feedback is presented, and multiple outdated estimates method is proposed to improve the system performance. Based on this method and imperfect feedback information, the closed-form expressions of spectral efficiency (SE and packet error rate (PER of the system subject to the target PER constraint are respectively derived. With these expressions, the system performance can be effectively evaluated. To mitigate the effect of delayed feedback, the variable thresholds (VTs are also derived by means of the maximum a posteriori method, and these VTs include the conventional fixed thresholds (FTs as special cases. Simulation results show that the theoretical SE and PER are in good agreement with the corresponding simulation. The proposed CLD scheme with multiple estimates can obtain higher SE than the existing CLD scheme with single estimate, especially for large delay. Moreover, the CLD scheme with VTs outperforms that with conventional FTs.

  4. A High-Throughput Biological Calorimetry Core: Steps to Startup, Run, and Maintain a Multiuser Facility.

    Science.gov (United States)

    Yennawar, Neela H; Fecko, Julia A; Showalter, Scott A; Bevilacqua, Philip C

    2016-01-01

    Many labs have conventional calorimeters where denaturation and binding experiments are setup and run one at a time. While these systems are highly informative to biopolymer folding and ligand interaction, they require considerable manual intervention for cleaning and setup. As such, the throughput for such setups is limited typically to a few runs a day. With a large number of experimental parameters to explore including different buffers, macromolecule concentrations, temperatures, ligands, mutants, controls, replicates, and instrument tests, the need for high-throughput automated calorimeters is on the rise. Lower sample volume requirements and reduced user intervention time compared to the manual instruments have improved turnover of calorimetry experiments in a high-throughput format where 25 or more runs can be conducted per day. The cost and efforts to maintain high-throughput equipment typically demands that these instruments be housed in a multiuser core facility. We describe here the steps taken to successfully start and run an automated biological calorimetry facility at Pennsylvania State University. Scientists from various departments at Penn State including Chemistry, Biochemistry and Molecular Biology, Bioengineering, Biology, Food Science, and Chemical Engineering are benefiting from this core facility. Samples studied include proteins, nucleic acids, sugars, lipids, synthetic polymers, small molecules, natural products, and virus capsids. This facility has led to higher throughput of data, which has been leveraged into grant support, attracting new faculty hire and has led to some exciting publications. © 2016 Elsevier Inc. All rights reserved.

  5. Substring Position Search over Encrypted Cloud Data Supporting Efficient Multi-User Setup

    Directory of Open Access Journals (Sweden)

    Mikhail Strizhov

    2016-07-01

    Full Text Available Existing Searchable Encryption (SE solutions are able to handle simple Boolean search queries, such as single or multi-keyword queries, but cannot handle substring search queries over encrypted data that also involve identifying the position of the substring within the document. These types of queries are relevant in areas such as searching DNA data. In this paper, we propose a tree-based Substring Position Searchable Symmetric Encryption (SSP-SSE to overcome the existing gap. Our solution efficiently finds occurrences of a given substring over encrypted cloud data. Specifically, our construction uses the position heap tree data structure and achieves asymptotic efficiency comparable to that of an unencrypted position heap tree. Our encryption takes O ( k n time, and the resulting ciphertext is of size O ( k n , where k is a security parameter and n is the size of stored data. The search takes O ( m 2 + o c c time and three rounds of communication, where m is the length of the queried substring and o c c is the number of occurrences of the substring in the document collection. We prove that the proposed scheme is secure against chosen-query attacks that involve an adaptive adversary. Finally, we extend SSP-SSE to the multi-user setting where an arbitrary group of cloud users can submit substring queries to search the encrypted data.

  6. Performance analysis of an opportunistic multi-user cognitive network with multiple primary users

    KAUST Repository

    Khan, Fahd Ahmed

    2014-03-01

    Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network with multiple users. The channel between the secondary network is assumed to have independent but not identical Nakagami-m fading. The interference channel between the secondary users (SUs) and the primary users is assumed to have Rayleigh fading. A power allocation based on the instantaneous channel state information is derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each SU. The uplink scenario is considered where a single SU is selected for transmission. This opportunistic selection depends on the transmission channel power gain and the interference channel power gain as well as the power allocation policy adopted at the users. Exact closed form expressions for the moment-generating function, outage performance, symbol error rate performance, and the ergodic capacity are derived. Numerical results corroborate the derived analytical results. The performance is also studied in the asymptotic regimes, and the generalized diversity gain of this scheduling scheme is derived. It is shown that when the interference channel is deeply faded and the peak transmit power constraint is relaxed, the scheduling scheme achieves full diversity and that increasing the number of primary users does not impact the diversity order. © 2014 John Wiley & Sons, Ltd.

  7. OFDM and MC-CDMA for broadband multi-user communications WLANs and broadcasting

    CERN Document Server

    2003-01-01

    "OFDM systems have experienced increased attention in recent years and have found applications in a number of diverse areas including telephone-line based ADSL links, digital audio and video broadcasting systems, and wireless local area networks. OFDM is being considered for the next-generation of wireless systems both with and without direct sequence spreading and the resultant spreading-based multi-carrier CDMA systems have numerous attractive properties. This volume provides the reader with a broad overview of the research on OFDM systems during their 40-year history. Part I commences with an easy to read conceptual, rather than mathematical, treatment of the basic design issues of OFDM systems. The discussions gradually deepen to include adaptive single and multi-user OFDM systems invoking adaptive turbo coding. Part II introduces the taxonomy of multi-carrier CDMA systems and deals with the design of their spreading codes and the objective of minimising their crest factors. This part also compares the be...

  8. On the performance of multiuser scheduling with post-examining under non-identical fading

    KAUST Repository

    Gaaloul, Fakhreddine; Alouini, Mohamed-Slim; Radaydeh, Redha M.; Yang, Hong-Chuan

    2012-01-01

    We investigate the performance of a multiuser downlink access scheme based on a post-selection switch and examine algorithm. The studied scheme sequentially switches over the users that experience independent and non-identically distributed fading conditions, and selects a single user with an acceptable channel quality as compared to a pre-selected signal-to-noise ratio (SNR) threshold. If no one of the users can satisfy the target channel quality, the base station (BS) takes the advantage of the knowledge of all users channels and serves the user with the best channel quality among all users. This scheme reduces considerably the feedback load but offers a lower average spectral efficiency (ASE) as compared to that of the full feedback system with instantaneous best user selection. On the other hand, it improves the system performances, such as outage probability and average bit error rate (BER), as compared to a system that is based on a standard switching scheme without post-selection. Numerical results for the ASE average BER, and average feed back load, are presented for the cases of outdated and non-outdated rate-adaptive modulation scheme operating over independent and non-identically distributed users.

  9. On the performance of multiuser scheduling with post-examining under non-identical fading

    KAUST Repository

    Gaaloul, Fakhreddine

    2012-06-11

    We investigate the performance of a multiuser downlink access scheme based on a post-selection switch and examine algorithm. The studied scheme sequentially switches over the users that experience independent and non-identically distributed fading conditions, and selects a single user with an acceptable channel quality as compared to a pre-selected signal-to-noise ratio (SNR) threshold. If no one of the users can satisfy the target channel quality, the base station (BS) takes the advantage of the knowledge of all users channels and serves the user with the best channel quality among all users. This scheme reduces considerably the feedback load but offers a lower average spectral efficiency (ASE) as compared to that of the full feedback system with instantaneous best user selection. On the other hand, it improves the system performances, such as outage probability and average bit error rate (BER), as compared to a system that is based on a standard switching scheme without post-selection. Numerical results for the ASE average BER, and average feed back load, are presented for the cases of outdated and non-outdated rate-adaptive modulation scheme operating over independent and non-identically distributed users.

  10. Performance analysis of switch-based multiuser scheduling schemes with adaptive modulation in spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2014-04-01

    This paper focuses on the development of multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, two scheduling schemes are proposed for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme focuses on optimizing the average spectral efficiency by selecting the user that reports the best channel quality. In order to alleviate the relatively high feedback required by the first scheme, a second scheme based on the concept of switched diversity is proposed, where the base station (BS) scans the secondary users in a sequential manner until a user whose channel quality is above an acceptable predetermined threshold is found. We develop expressions for the statistics of the signal-to-interference and noise ratio as well as the average spectral efficiency, average feedback load, and the delay at the secondary BS. We then present numerical results for the effect of the number of users and the interference constraint on the optimal switching threshold and the system performance and show that our analysis results are in perfect agreement with the numerical results. © 2014 John Wiley & Sons, Ltd.

  11. Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa

    2012-12-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

  12. X-Switch: An Efficient , Multi-User, Multi-Language Web Application Server

    Directory of Open Access Journals (Sweden)

    Mayumbo Nyirenda

    2010-07-01

    Full Text Available Web applications are usually installed on and accessed through a Web server. For security reasons, these Web servers generally provide very few privileges to Web applications, defaulting to executing them in the realm of a guest ac- count. In addition, performance often is a problem as Web applications may need to be reinitialised with each access. Various solutions have been designed to address these security and performance issues, mostly independently of one another, but most have been language or system-specic. The X-Switch system is proposed as an alternative Web application execution environment, with more secure user-based resource management, persistent application interpreters and support for arbitrary languages/interpreters. Thus it provides a general-purpose environment for developing and deploying Web applications. The X-Switch system's experimental results demonstrated that it can achieve a high level of performance. Further- more it was shown that X-Switch can provide functionality matching that of existing Web application servers but with the added benet of multi-user support. Finally the X-Switch system showed that it is feasible to completely separate the deployment platform from the application code, thus ensuring that the developer does not need to modify his/her code to make it compatible with the deployment platform.

  13. Joint multiuser switched diversity and adaptive modulation schemes for spectrum sharing systems

    KAUST Repository

    Qaraqe, Marwa; Abdallah, Mohamed M.; Serpedin, Erchin; Alouini, Mohamed-Slim; Alnuweiri, Hussein M.

    2012-01-01

    In this paper, we develop multiuser access schemes for spectrum sharing systems whereby secondary users are allowed to share the spectrum with primary users under the condition that the interference observed at the primary receiver is below a predetermined threshold. In particular, we devise two schemes for selecting a user among those that satisfy the interference constraint and achieve an acceptable signal-to-noise ratio level. The first scheme selects the user that reports the best channel quality. In order to alleviate the high feedback load associated with the first scheme, we develop a second scheme based on the concept of switched diversity where the base station scans the users in a sequential manner until an acceptable user is found. In addition to these two selection schemes, we consider two power adaptive settings at the secondary users based on the amount of interference available at the secondary transmitter. In the On/Off power setting, users are allowed to transmit based on whether the interference constraint is met or not, while in the full power adaptive setting, the users are allowed to vary their transmission power to satisfy the interference constraint. Finally, we present numerical results for our proposed algorithms where we show the trade-off between the average spectral efficiency and average feedback load for both schemes. © 2012 IEEE.

  14. Block compressed sensing for feedback reduction in relay-aided multiuser full duplex networks

    KAUST Repository

    Elkhalil, Khalil; Eltayeb, Mohammed; Kammoun, Abla; Al-Naffouri, Tareq Y.; Bahrami, Hamid Reza

    2016-01-01

    Opportunistic user selection is a simple technique that exploits the spatial diversity in multiuser relay-aided networks. Nonetheless, channel state information (CSI) from all users (and cooperating relays) is generally required at a central node in order to make selection decisions. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the presence of a full-duplex cooperating relay corrupts the fed back CSI by additive noise and the relay's loop (or self) interference. This could lead to transmission outages if user selection is based on inaccurate feedback information. In this paper, we propose an opportunistic full-duplex feedback algorithm that tackles the above challenges. We cast the problem of joint user signal-to-noise ratio (SNR) and the relay loop interference estimation at the base-station as a block sparse signal recovery problem in compressive sensing (CS). Using existing CS block recovery algorithms, the identity of the strong users is obtained and their corresponding SNRs are estimated. Numerical results show that the proposed technique drastically reduces the feedback overhead and achieves a rate close to that obtained by techniques that require dedicated error-free feedback from all users. Numerical results also show that there is a trade-off between the feedback interference and load, and for short coherence intervals, full-duplex feedback achieves higher throughput when compared to interference-free (half-duplex) feedback. © 2016 IEEE.

  15. Convex blind image deconvolution with inverse filtering

    Science.gov (United States)

    Lv, Xiao-Guang; Li, Fang; Zeng, Tieyong

    2018-03-01

    Blind image deconvolution is the process of estimating both the original image and the blur kernel from the degraded image with only partial or no information about degradation and the imaging system. It is a bilinear ill-posed inverse problem corresponding to the direct problem of convolution. Regularization methods are used to handle the ill-posedness of blind deconvolution and get meaningful solutions. In this paper, we investigate a convex regularized inverse filtering method for blind deconvolution of images. We assume that the support region of the blur object is known, as has been done in a few existing works. By studying the inverse filters of signal and image restoration problems, we observe the oscillation structure of the inverse filters. Inspired by the oscillation structure of the inverse filters, we propose to use the star norm to regularize the inverse filter. Meanwhile, we use the total variation to regularize the resulting image obtained by convolving the inverse filter with the degraded image. The proposed minimization model is shown to be convex. We employ the first-order primal-dual method for the solution of the proposed minimization model. Numerical examples for blind image restoration are given to show that the proposed method outperforms some existing methods in terms of peak signal-to-noise ratio (PSNR), structural similarity (SSIM), visual quality and time consumption.

  16. NENIMF: Northeast National Ion Microprobe Facility - A Multi-User Facility for SIMS Microanalysis

    Science.gov (United States)

    Layne, G. D.; Shimizu, N.

    2002-12-01

    The MIT-Brown-Harvard Regional Ion Microprobe Facility was one of the earliest multi-user facilities enabled by Dan Weill's Instrumentation and Facilities Program - and began with the delivery of a Cameca IMS 3f ion microprobe to MIT in 1978. The Northeast National Ion Microprobe Facility (NENIMF) is the direct descendant of this original facility. Now housed at WHOI, the facility incorporates both the original IMS 3f, and a new generation, high transmission-high resolution instrument - the Cameca IMS 1270. Purchased with support from NSF, and from a consortium of academic institutions in the Northeast (The American Museum of Natural History, Brown University, The Lamont-Doherty Earth Observatory, MIT, Rensselaer Polytechnic Institute, WHOI) - this latest instrument was delivered and installed during 1996. NENIMF continues to be supported by NSF EAR I&F as a multi-user facility for geochemical research. Work at NENIMF has extended the original design strength of the IMS 1270 for microanalytical U-Pb zircon geochronology to a wide variety of novel and improved techniques for geochemical research. Isotope microanalysis for studies in volcanology and petrology is currently the largest single component of facility activity. This includes the direct measurement of Pb isotopes in melt inclusions, an application developed at NENIMF, which is making an increasingly significant contribution to our understanding of basalt petrogenesis. This same technique has also been extended to the determination of Pb isotopes in detrital feldspar grains, for the study of sedimentary provenance and tectonics of the Himalayas and other terrains. The determination of δ11B in volcanic melt inclusions has also proven to be a powerful tool in the modeling of subduction-related magmatism. The recent development of δ34S and δ37Cl determination in glasses is being applied to studies of the behavior of these volatile elements in both natural and experimental systems. Other recent undertakings

  17. Tunable optical frequency comb enabled scalable and cost-effective multiuser orthogonal frequency-division multiple access passive optical network with source-free optical network units.

    Science.gov (United States)

    Chen, Chen; Zhang, Chongfu; Liu, Deming; Qiu, Kun; Liu, Shuang

    2012-10-01

    We propose and experimentally demonstrate a multiuser orthogonal frequency-division multiple access passive optical network (OFDMA-PON) with source-free optical network units (ONUs), enabled by tunable optical frequency comb generation technology. By cascading a phase modulator (PM) and an intensity modulator and dynamically controlling the peak-to-peak voltage of a PM driven signal, a tunable optical frequency comb source can be generated. It is utilized to assist the configuration of a multiple source-free ONUs enhanced OFDMA-PON where simultaneous and interference-free multiuser upstream transmission over a single wavelength can be efficiently supported. The proposed multiuser OFDMA-PON is scalable and cost effective, and its feasibility is successfully verified by experiment.

  18. Robust THP Transceiver Designs for Multiuser MIMO Downlink with Imperfect CSIT

    Directory of Open Access Journals (Sweden)

    P. Ubaidulla

    2009-01-01

    Full Text Available We present robust joint nonlinear transceiver designs for multiuser multiple-input multiple-output (MIMO downlink in the presence of imperfections in the channel state information at the transmitter (CSIT. The base station (BS is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas. The BS employs Tomlinson-Harashima precoding (THP for interuser interference precancellation at the transmitter. We consider robust transceiver designs that jointly optimize the transmit THP filters and receive filter for two models of CSIT errors. The first model is a stochastic error (SE model, where the CSIT error is Gaussian-distributed. This model is applicable when the CSIT error is dominated by channel estimation error. In this case, the proposed robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. The other model we consider is a norm-bounded error (NBE model, where the CSIT error can be specified by an uncertainty set. This model is applicable when the CSIT error is dominated by quantization errors. In this case, we consider a worst-case design. For this model, we consider robust (i minimum SMSE, (ii MSE-constrained, and (iii MSE-balancing transceiver designs. We propose iterative algorithms to solve these problems, wherein each iteration involves a pair of semidefinite programs (SDPs. Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We evaluate the robustness of the proposed algorithms to imperfections in CSIT through simulation, and show that the proposed robust designs outperform nonrobust designs as well as robust linear transceiver designs reported in the recent literature.

  19. Robust THP Transceiver Designs for Multiuser MIMO Downlink with Imperfect CSIT

    Science.gov (United States)

    Ubaidulla, P.; Chockalingam, A.

    2009-12-01

    We present robust joint nonlinear transceiver designs for multiuser multiple-input multiple-output (MIMO) downlink in the presence of imperfections in the channel state information at the transmitter (CSIT). The base station (BS) is equipped with multiple transmit antennas, and each user terminal is equipped with one or more receive antennas. The BS employs Tomlinson-Harashima precoding (THP) for interuser interference precancellation at the transmitter. We consider robust transceiver designs that jointly optimize the transmit THP filters and receive filter for two models of CSIT errors. The first model is a stochastic error (SE) model, where the CSIT error is Gaussian-distributed. This model is applicable when the CSIT error is dominated by channel estimation error. In this case, the proposed robust transceiver design seeks to minimize a stochastic function of the sum mean square error (SMSE) under a constraint on the total BS transmit power. We propose an iterative algorithm to solve this problem. The other model we consider is a norm-bounded error (NBE) model, where the CSIT error can be specified by an uncertainty set. This model is applicable when the CSIT error is dominated by quantization errors. In this case, we consider a worst-case design. For this model, we consider robust (i) minimum SMSE, (ii) MSE-constrained, and (iii) MSE-balancing transceiver designs. We propose iterative algorithms to solve these problems, wherein each iteration involves a pair of semidefinite programs (SDPs). Further, we consider an extension of the proposed algorithm to the case with per-antenna power constraints. We evaluate the robustness of the proposed algorithms to imperfections in CSIT through simulation, and show that the proposed robust designs outperform nonrobust designs as well as robust linear transceiver designs reported in the recent literature.

  20. Equalization of Multiuser Wireless CDMA Downlink Considering Transmitter Nonlinearity Using Walsh Codes

    Directory of Open Access Journals (Sweden)

    Pinter Stephen Z

    2007-01-01

    Full Text Available Transmitter nonlinearity has been a major issue in many scenarios: cellular wireless systems have high power RF amplifier (HPA nonlinearity at the base station; satellite downlinks have nonlinear TWT amplifiers in the satellite transponder and multipath conditions in the ground station; and radio-over-fiber (ROF systems consist of a nonlinear optical link followed by a wireless channel. In many cases, the nonlinearity is simply ignored if there is no out-of-band emission. This results in poor BER performance. In this paper we propose a new technique to estimate the linear part of the wireless downlink in the presence of a nonlinearity using Walsh codes; Walsh codes are commonly used in CDMA downlinks. Furthermore, we show that equalizer performance is significantly improved by taking into account the presence of the nonlinearity during channel estimation. This is shown by using a regular decision feedback equalizer (DFE with both wireless and RF amplifier noise. We perform estimation in a multiuser CDMA communication system where all users transmit their signal simultaneously. Correlation analysis is applied to identify the channel impulse response (CIR and the derivation of key correlation relationships is shown. A difficulty with using Walsh codes in terms of their correlations (compared to PN sequences is then presented, as well as a discussion on how to overcome it. Numerical evaluations show a good estimation of the linear system with 54 users in the downlink and a signal-to-noise ratio (SNR of 25 dB. Bit error rate (BER simulations of the proposed identification and equalization algorithms show a BER of achieved at an SNR of dB.

  1. Two-Way Multiuser Mixed RF/FSO Relaying: Performance Analysis and Power Allocation

    KAUST Repository

    Al-Eryani, Yasser F.

    2018-03-21

    In this paper, the performance of two-way multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. RF links are used to conduct data transmission between users and relay node, while a FSO link is used to conduct data transmission on the last-mile communication link between the relay node and base station. The RF links are assumed to follow a Rayleigh fading model, while the FSO links are assumed to follow a unified Gamma-Gamma atmospheric turbulence fading model with pointing error. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ratio) outage probability, average symbol error rate, and average ergodic channel capacity are derived assuming a heterodyne detection scheme. The asymptotic results are used to conduct a power optimization algorithm where expressions for optimal transmission power values for the transmitting nodes are provided. Additionally, performance comparisons between the considered two-way-relaying (TWR) network and the oneway- relaying (OWR) network are provided and discussed. Also, the impact of several system parameters, including number of users, pointing errors, atmospheric turbulence conditions, and outage probability threshold on the overall network performance are investigated. All the theoretical results are validated by Monte Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of the OWR scheme with the same outage performance. Additionally, it is shown that under weak-to-moderate weather turbulence conditions and small pointing error, the outage probability is dominated by the RF downlink with a neglected effect for the user selection process at the RF uplink transmission. However, for severe pointing error, the outage probability is dominated by the FSO uplink/downlink transmission.

  2. MIMO wireless networks channels, techniques and standards for multi-antenna, multi-user and multi-cell systems

    CERN Document Server

    Clerckx, Bruno

    2013-01-01

    This book is unique in presenting channels, techniques and standards for the next generation of MIMO wireless networks. Through a unified framework, it emphasizes how propagation mechanisms impact the system performance under realistic power constraints. Combining a solid mathematical analysis with a physical and intuitive approach to space-time signal processing, the book progressively derives innovative designs for space-time coding and precoding as well as multi-user and multi-cell techniques, taking into consideration that MIMO channels are often far from ideal. Reflecting developments

  3. Multi-User Interference Cancellation Scheme(s) for Muliple Carrier Frequency Offset Compensation in Uplink OFDMA

    DEFF Research Database (Denmark)

    Nguyen, Huan Cong; Carvalho, Elisabeth De; Prasad, Ramjee

    2006-01-01

    (ICI) and degrade the system performance considerably. In this paper, we propose a novel Multi-User Interference (MUI) cancellation scheme for uplink OFDMA, which utilizes multiple OFDM-demodulators architecture to correct and then compensate the negative effects of multiple CFOs at the receiver's side......We consider the uplink of an Orthogonal Frequency Division Multiple Access (OFDMA)-based system, where each Mobile Station (MS) experiences a different Carrier Frequency Offset (CFO). Uncorrected CFO destroy the orthogonality among subcarriers, which could cause severe Inter-Carrier Interference...

  4. Blind Measurement Selection: A Random Matrix Theory Approach

    KAUST Repository

    Elkhalil, Khalil

    2016-12-14

    This paper considers the problem of selecting a set of $k$ measurements from $n$ available sensor observations. The selected measurements should minimize a certain error function assessing the error in estimating a certain $m$ dimensional parameter vector. The exhaustive search inspecting each of the $n\\\\choose k$ possible choices would require a very high computational complexity and as such is not practical for large $n$ and $k$. Alternative methods with low complexity have recently been investigated but their main drawbacks are that 1) they require perfect knowledge of the measurement matrix and 2) they need to be applied at the pace of change of the measurement matrix. To overcome these issues, we consider the asymptotic regime in which $k$, $n$ and $m$ grow large at the same pace. Tools from random matrix theory are then used to approximate in closed-form the most important error measures that are commonly used. The asymptotic approximations are then leveraged to select properly $k$ measurements exhibiting low values for the asymptotic error measures. Two heuristic algorithms are proposed: the first one merely consists in applying the convex optimization artifice to the asymptotic error measure. The second algorithm is a low-complexity greedy algorithm that attempts to look for a sufficiently good solution for the original minimization problem. The greedy algorithm can be applied to both the exact and the asymptotic error measures and can be thus implemented in blind and channel-aware fashions. We present two potential applications where the proposed algorithms can be used, namely antenna selection for uplink transmissions in large scale multi-user systems and sensor selection for wireless sensor networks. Numerical results are also presented and sustain the efficiency of the proposed blind methods in reaching the performances of channel-aware algorithms.

  5. Semi-blind sparse image reconstruction with application to MRFM.

    Science.gov (United States)

    Park, Se Un; Dobigeon, Nicolas; Hero, Alfred O

    2012-09-01

    We propose a solution to the image deconvolution problem where the convolution kernel or point spread function (PSF) is assumed to be only partially known. Small perturbations generated from the model are exploited to produce a few principal components explaining the PSF uncertainty in a high-dimensional space. Unlike recent developments on blind deconvolution of natural images, we assume the image is sparse in the pixel basis, a natural sparsity arising in magnetic resonance force microscopy (MRFM). Our approach adopts a Bayesian Metropolis-within-Gibbs sampling framework. The performance of our Bayesian semi-blind algorithm for sparse images is superior to previously proposed semi-blind algorithms such as the alternating minimization algorithm and blind algorithms developed for natural images. We illustrate our myopic algorithm on real MRFM tobacco virus data.

  6. Oplysningens blinde vinkler

    DEFF Research Database (Denmark)

    Hendricks, Vincent Fella; Hansen, Pelle Guldborg

    manipulation og fordrejning, til at påvirke menneskers overvejelser, beslutninger og handlinger, både individuelt og kollektivt, hvilket i sidste ende kan få betydning for de demokratiske processer. Oplysningens blinde vinkler gennemgår en række informationsfænomener, som optræder i vores dagligdag, og den...

  7. Leading Causes of Blindness

    Science.gov (United States)

    ... have cataracts. They are the leading cause of blindness in the world. By age 80, more than half of all people in the United States either will have a cataract or have had cataract surgery. Common symptoms are: Blurry vision Colors that seem faded Glare Not being able to ...

  8. Blind Loop Syndrome

    Science.gov (United States)

    ... or scleroderma involving the small intestine History of radiation therapy to the abdomen Diabetes Diverticulosis of the small intestine Complications A blind loop can cause escalating problems, including: Poor absorption of fats. Bacteria in your small intestine break down the bile ...

  9. Stochastic Blind Motion Deblurring

    KAUST Repository

    Xiao, Lei; Gregson, James; Heide, Felix; Heidrich, Wolfgang

    2015-01-01

    Blind motion deblurring from a single image is a highly under-constrained problem with many degenerate solutions. A good approximation of the intrinsic image can therefore only be obtained with the help of prior information in the form of (often non

  10. Postural control in blind subjects.

    Science.gov (United States)

    Soares, Antonio Vinicius; Oliveira, Cláudia Silva Remor de; Knabben, Rodrigo José; Domenech, Susana Cristina; Borges Junior, Noe Gomes

    2011-12-01

    To analyze postural control in acquired and congenitally blind adults. A total of 40 visually impaired adults participated in the research, divided into 2 groups, 20 with acquired blindness and 20 with congenital blindness - 21 males and 19 females, mean age 35.8 ± 10.8. The Brazilian version of Berg Balance Scale and the motor domain of functional independence measure were utilized. On Berg Balance Scale the mean for acquired blindness was 54.0 ± 2.4 and 54.4 ± 2.5 for congenitally blind subjects; on functional independence measure the mean for acquired blind group was 87.1 ± 4.8 and 87.3 ± 2.3 for congenitally blind group. Based upon the scale used the results suggest the ability to control posture can be developed by compensatory mechanisms and it is not affected by visual loss in congenitally and acquired blindness.

  11. Postural control in blind subjects

    Directory of Open Access Journals (Sweden)

    Antonio Vinicius Soares

    2011-12-01

    Full Text Available Objective: To analyze postural control in acquired and congenitally blind adults. Methods: A total of 40 visually impaired adults participated in the research, divided into 2 groups, 20 with acquired blindness and 20 with congenital blindness - 21 males and 19 females, mean age 35.8 ± 10.8. The Brazilian version of Berg Balance Scale and the motor domain of functional independence measure were utilized. Results: On Berg Balance Scale the mean for acquired blindness was 54.0 ± 2.4 and 54.4 ± 2.5 for congenitally blind subjects; on functional independence measure the mean for acquired blind group was 87.1 ± 4.8 and 87.3 ± 2.3 for congenitally blind group. Conclusion: Based upon the scale used the results suggest the ability to control posture can be developed by compensatory mechanisms and it is not affected by visual loss in congenitally and acquired blindness.

  12. Improved Interference-Free Channel Allocation in Coordinated Multiuser Multi-Antenna Open-Access Small Cells

    KAUST Repository

    Radaydeh, Redha; Zafar, Ammar; Al-Qahtani, Fawaz; Alouini, Mohamed-Slim

    2016-01-01

    This paper investigates low-complexity joint interference avoidance and desired link improvement for single channel allocation in multiuser multi-antenna access points (APs) for open-access small cells. It is considered that an active user is equipped with an atenna array that can be used to suppress interference sources but not to provide spatial diversity. On the other hand, the operation of APs can be coordinated to meet design requirements, and each of which can unconditionally utilize assigned physical channels. Moreover, each AP is equipped with uncorrelated antennas that can be reused simultaneously to serve many active users. The analysis provides new approaches to exploit physical channels, transmit antennas, and APs to mitigate interference, while providing the best possible link gain to an active user through the most suitable interference-free channel. The event of concurrent service requests placed by active users on a specific interference-free channel is discussed for either interference avoidance through identifying unshared channels or desired link improvement via multiuser scheduling. The applicability of the approaches to balance downlink loads is explained, and practical scenarios due to imperfect identification of interference-free channels and/or scheduled user are thoroughly investigated. The developed results are applicable for any statistical and geometric models of the allocated channel to an active user as well as channel conditions of interference users. They can be used to study various performance measures. Numerical and simulation results are presented to explain some outcomes of this work.

  13. Sum-Rate Enhancement in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2016-09-20

    In this paper, we consider a multiuser multipleinput multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting (EH) relays and multiple destinations. All the nodes are equipped with multiple antennas. The EH and information decoding (ID) tasks at the relays and destinations are separated over the time, which is termed as the time switching (TS) scheme. As optimal solutions for the sum-rate maximization problems of BC channels and the MIMO interference channels are hard to obtain, the end-to-end sum rate maximization problem of a multiuser MIMO DF relay BC channel is even harder. In this paper, we propose to tackle a simplified problem where we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relaydestination channels using an algorithm similar to the BD method. In order to show the relevance of our low complex proposed solution, we compare it to the minimum mean-square error (MMSE) solution that was shown in the literature to be equivalent to the solution of the sum-rate maximization in MIMO broadcasting interfering channels. We also investigate the time division multiple access (TDMA) solution which separates all the information transmissions from the source to the relays and from the relays to the destinations over time. We provide numerical results to show the relevance of our proposed solution, in comparison with the no co-channel interference (CCI) case, the TDMA based solution and the MMSE based solution.

  14. Improved Interference-Free Channel Allocation in Coordinated Multiuser Multi-Antenna Open-Access Small Cells

    KAUST Repository

    Radaydeh, Redha

    2016-02-16

    This paper investigates low-complexity joint interference avoidance and desired link improvement for single channel allocation in multiuser multi-antenna access points (APs) for open-access small cells. It is considered that an active user is equipped with an atenna array that can be used to suppress interference sources but not to provide spatial diversity. On the other hand, the operation of APs can be coordinated to meet design requirements, and each of which can unconditionally utilize assigned physical channels. Moreover, each AP is equipped with uncorrelated antennas that can be reused simultaneously to serve many active users. The analysis provides new approaches to exploit physical channels, transmit antennas, and APs to mitigate interference, while providing the best possible link gain to an active user through the most suitable interference-free channel. The event of concurrent service requests placed by active users on a specific interference-free channel is discussed for either interference avoidance through identifying unshared channels or desired link improvement via multiuser scheduling. The applicability of the approaches to balance downlink loads is explained, and practical scenarios due to imperfect identification of interference-free channels and/or scheduled user are thoroughly investigated. The developed results are applicable for any statistical and geometric models of the allocated channel to an active user as well as channel conditions of interference users. They can be used to study various performance measures. Numerical and simulation results are presented to explain some outcomes of this work.

  15. Sum-Rate Enhancement in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma; Salem, Ahmed Sultan; Alouini, Mohamed-Slim

    2016-01-01

    In this paper, we consider a multiuser multipleinput multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting (EH) relays and multiple destinations. All the nodes are equipped with multiple antennas. The EH and information decoding (ID) tasks at the relays and destinations are separated over the time, which is termed as the time switching (TS) scheme. As optimal solutions for the sum-rate maximization problems of BC channels and the MIMO interference channels are hard to obtain, the end-to-end sum rate maximization problem of a multiuser MIMO DF relay BC channel is even harder. In this paper, we propose to tackle a simplified problem where we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relaydestination channels using an algorithm similar to the BD method. In order to show the relevance of our low complex proposed solution, we compare it to the minimum mean-square error (MMSE) solution that was shown in the literature to be equivalent to the solution of the sum-rate maximization in MIMO broadcasting interfering channels. We also investigate the time division multiple access (TDMA) solution which separates all the information transmissions from the source to the relays and from the relays to the destinations over time. We provide numerical results to show the relevance of our proposed solution, in comparison with the no co-channel interference (CCI) case, the TDMA based solution and the MMSE based solution.

  16. Partial tooth gear bearings

    Science.gov (United States)

    Vranish, John M. (Inventor)

    2010-01-01

    A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

  17. The blind leading the blind: use and misuse of blinding in randomized controlled trials.

    Science.gov (United States)

    Miller, Larry E; Stewart, Morgan E

    2011-03-01

    The use of blinding strengthens the credibility of randomized controlled trials (RCTs) by minimizing bias. However, there is confusion surrounding the definition of blinding as well as the terms single, double, and triple blind. It has been suggested that these terms should be discontinued due to their broad misinterpretation. We recommend that, instead of abandoning the use of these terms, explicit definitions of blinding should be adopted. We address herein the concept of blinding, propose standard definitions for the consistent use of these terms, and detail when different types of blinding should be utilized. Standardizing the definition of blinding and utilizing proper blinding methods will improve the quality and clarity of reporting in RCTs. Copyright © 2010 Elsevier Inc. All rights reserved.

  18. Import and visualization of clinical medical imagery into multiuser VR environments

    Science.gov (United States)

    Mehrle, Andreas H.; Freysinger, Wolfgang; Kikinis, Ron; Gunkel, Andreas; Kral, Florian

    2005-03-01

    The graphical representation of three-dimensional data obtained from tomographic imaging has been the central problem since this technology is available. Neither the representation as a set of two-dimensional slices nor the 2D projection of three-dimensional models yields satisfactory results. In this paper a way is outlined which permits the investigation of volumetric clinical data obtained from standard CT, MR, PET, SPECT or experimental very high resolution CT-scanners in a three dimensional environment within a few worksteps. Volumetric datasets are converted into surface data (segmentation process) using the 3D-Slicer software tool and saved as .vtk files and exported as a collection of primitives in any common file format (.iv, .pfb). Subsequently this files can be displayed and manipulated in the CAVE virtual reality center. The CAVE is a multiuser walkable virtual room consisting of several walls on which stereoscopic images are projected by rear panel beamers. Adequate tracking of the head position and separate image calculation for each eye yields a vivid impression for one or several users. With the use of a seperately tracked 6D joystick manipulations such as rotation, translation, zooming, decomposition or highlighting can be done intuitively. The usage of the CAVE technology opens new possibilities especially in surgical training ("hands-on-effect") and as an educational tool (availability of pathological data). Unlike concurring technologies the CAVE permits a walk-through into the virtual scene but preserves enough physical perception to allow interaction between multiple users, e.g. gestures and movements. By training in a virtual environment on one hand the learning process of students in complex anatomic findings may be improved considerably and on the other hand unaccustomed views such as the one through a microscope or endoscope can be trained in advance. The availability of low-cost PC based CAVE-like systems and the rapidly decreasing price

  19. Essays on partial retirement

    NARCIS (Netherlands)

    Kantarci, T.

    2012-01-01

    The five essays in this dissertation address a range of topics in the micro-economic literature on partial retirement. The focus is on the labor market behavior of older age groups. The essays examine the economic and non-economic determinants of partial retirement behavior, the effect of partial

  20. INTRODUCTION Childhood blindness is increasingly becoming a ...

    African Journals Online (AJOL)

    number of blind years resulting from blindness in children is also equal to the number of blind years due to age related cataract.10 The burden of disability in terms of blind years in these children represents a major. CAUSES OF BLINDNESS AND VISUAL IMPAIRMENT AT THE SCHOOL FOR THE. BLIND OWO, NIGERIA.

  1. The Impact of Student Self-Efficacy on Scientific Inquiry Skills: An Exploratory Investigation in "River City," a Multi-User Virtual Environment

    Science.gov (United States)

    Ketelhut, Diane Jass

    2007-01-01

    This exploratory study investigated data-gathering behaviors exhibited by 100 seventh-grade students as they participated in a scientific inquiry-based curriculum project delivered by a multi-user virtual environment (MUVE). This research examined the relationship between students' self-efficacy on entry into the authentic scientific activity and…

  2. Stochastic Blind Motion Deblurring

    KAUST Repository

    Xiao, Lei

    2015-05-13

    Blind motion deblurring from a single image is a highly under-constrained problem with many degenerate solutions. A good approximation of the intrinsic image can therefore only be obtained with the help of prior information in the form of (often non-convex) regularization terms for both the intrinsic image and the kernel. While the best choice of image priors is still a topic of ongoing investigation, this research is made more complicated by the fact that historically each new prior requires the development of a custom optimization method. In this paper, we develop a stochastic optimization method for blind deconvolution. Since this stochastic solver does not require the explicit computation of the gradient of the objective function and uses only efficient local evaluation of the objective, new priors can be implemented and tested very quickly. We demonstrate that this framework, in combination with different image priors produces results with PSNR values that match or exceed the results obtained by much more complex state-of-the-art blind motion deblurring algorithms.

  3. Recurrent Partial Words

    Directory of Open Access Journals (Sweden)

    Francine Blanchet-Sadri

    2011-08-01

    Full Text Available Partial words are sequences over a finite alphabet that may contain wildcard symbols, called holes, which match or are compatible with all letters; partial words without holes are said to be full words (or simply words. Given an infinite partial word w, the number of distinct full words over the alphabet that are compatible with factors of w of length n, called subwords of w, refers to a measure of complexity of infinite partial words so-called subword complexity. This measure is of particular interest because we can construct partial words with subword complexities not achievable by full words. In this paper, we consider the notion of recurrence over infinite partial words, that is, we study whether all of the finite subwords of a given infinite partial word appear infinitely often, and we establish connections between subword complexity and recurrence in this more general framework.

  4. The role of figure-ground segregation in change blindness.

    Science.gov (United States)

    Landman, Rogier; Spekreijse, Henk; Lamme, Victor A F

    2004-04-01

    Partial report methods have shown that a large-capacity representation exists for a few hundred milliseconds after a picture has disappeared. However, change blindness studies indicate that very limited information remains available when a changed version of the image is presented subsequently. What happens to the large-capacity representation? New input after the first image may interfere, but this is likely to depend on the characteristics of the new input. In our first experiment, we show that a display containing homogeneous image elements between changing images does not render the large-capacity representation unavailable. Interference occurs when these new elements define objects. On that basis we introduce a new method to produce change blindness: The second experiment shows that change blindness can be induced by redefining figure and background, without an interval between the displays. The local features (line segments) that defined figures and background were swapped, while the contours of the figures remained where they were. Normally, changes are easily detected when there is no interval. However, our paradigm results in massive change blindness. We propose that in a change blindness experiment, there is a large-capacity representation of the original image when it is followed by a homogeneous interval display, but that change blindness occurs whenever the changed image forces resegregation of figures from the background.

  5. Heavy-tailed distribution of the SSH Brute-force attack duration in a multi-user environment

    Science.gov (United States)

    Lee, Jae-Kook; Kim, Sung-Jun; Park, Chan Yeol; Hong, Taeyoung; Chae, Huiseung

    2016-07-01

    Quite a number of cyber-attacks to be place against supercomputers that provide highperformance computing (HPC) services to public researcher. Particularly, although the secure shell protocol (SSH) brute-force attack is one of the traditional attack methods, it is still being used. Because stealth attacks that feign regular access may occur, they are even harder to detect. In this paper, we introduce methods to detect SSH brute-force attacks by analyzing the server's unsuccessful access logs and the firewall's drop events in a multi-user environment. Then, we analyze the durations of the SSH brute-force attacks that are detected by applying these methods. The results of an analysis of about 10 thousands attack source IP addresses show that the behaviors of abnormal users using SSH brute-force attacks are based on human dynamic characteristics of a typical heavy-tailed distribution.

  6. Performance of DS-UWB in MB-OFDM and multi-user interference over Nakagami-m fading channels

    KAUST Repository

    Mehbodniya, Abolfazl

    2011-01-18

    The mutual interference between the two ultra wideband (UWB) technologies, which use the same frequency spectrum, will be a matter of concern in the near future. In this context, we present a performance analysis of direct-sequence (DS) UWB communication in the presence of multiband orthogonal frequency division multiplexing (MB-OFDM) UWB interfering transmissions. The channel fading is modeled according to Nakagami-m distribution, and multi-user interference is taken into account. The DS-UWB system performance is evaluated in terms of bit error rate (BER). Specifically, using the characteristic function approach, an analytical expression for the average BER is derived conditioned on the channel impulse response. Numerical and simulation results are provided and compared for different coexistence scenarios. © 2011 John Wiley & Sons, Ltd.

  7. On the performance of two-way multiuser mixed RF/FSO relay networks with opportunistic scheduling & asymmetric channel gains

    KAUST Repository

    Al-Eryani, Yasser F.; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, the performance of two-way relaying (TWR) multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ration (SNR)) outage probability, and average ergodic channel capacity are derived assuming heterodyne detection (HD) scheme. Additionally, impacts of several system parameters including number of users, pointing errors, and atmospheric turbulence conditions on the overall network performance are investigated. All the theoretical results are validated by Monte-Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of one-way relaying (OWR) scheme with the same outage performance. Additionally, the overall diversity order of the network is shown to be affected not only by the number of users, but it is also a function of the pointing error and atmospheric turbulence conditions.

  8. On the performance of two-way multiuser mixed RF/FSO relay networks with opportunistic scheduling & asymmetric channel gains

    KAUST Repository

    Al-Eryani, Yasser F.

    2017-07-20

    In this paper, the performance of two-way relaying (TWR) multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ration (SNR)) outage probability, and average ergodic channel capacity are derived assuming heterodyne detection (HD) scheme. Additionally, impacts of several system parameters including number of users, pointing errors, and atmospheric turbulence conditions on the overall network performance are investigated. All the theoretical results are validated by Monte-Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of one-way relaying (OWR) scheme with the same outage performance. Additionally, the overall diversity order of the network is shown to be affected not only by the number of users, but it is also a function of the pointing error and atmospheric turbulence conditions.

  9. Motor development of blind toddler

    OpenAIRE

    Likar, Petra

    2013-01-01

    For blind toddlers, development of motor skills enables possibilities for learning and exploring the environment. The purpose of this graduation thesis is to systematically mark the milestones in development of motor skills in blind toddlers, to establish different factors which affect this development, and to discover different ways for teachers for visually impaired and parents to encourage development of motor skills. It is typical of blind toddlers that they do not experience a wide varie...

  10. Performance Analysis of Capacity of MIMO Systems under Multiuser Interference Based on Worst-Case Noise Behavior

    Directory of Open Access Journals (Sweden)

    Jorswieck E. A.

    2004-01-01

    Full Text Available The capacity of a cellular multiuser MIMO system depends on various parameters, for example, the system structure, the transmit and receive strategies, the channel state information at the transmitter and the receiver, and the channel properties. Recently, the main focus of research was on single-user MIMO systems, their channel capacity, and their error performance with space-time coding. In general, the capacity of a cellular multiuser MIMO system is limited by additive white Gaussian noise, intracell interference from other users within the cell, and intercell interference from users outside the considered cell. We study one point-to-point link, on which interference acts. The interference models the different system scenarios and various parameters. Therefore, we consider three scenarios in which the noise is subject to different constraints. A general trace constraint is used in the first scenario. The noise covariance matrix eigenvalues are kept fixed in the second scenario, and in the third scenario the entries on the diagonal of the noise covariance matrix are kept fixed. We assume that the receiver as well as the transmitter have perfect channel state information. We solve the corresponding minimax programming problems and characterize the worst-case noise and the optimal transmit strategy. In all scenarios, the achievable capacity of the MIMO system with worst-case noise is equal to the capacity of some MIMO system in which either the channels are orthogonal or the transmit antennas are not allowed to cooperate or in which no channel state information is available at the transmitter. Furthermore, the minimax expressions fulfill a saddle point property. All theoretical results are illustrated by examples and numerical simulations.

  11. Power Consumption Efficiency Evaluation of Multi-User Full-Duplex Visible Light Communication Systems for Smart Home Technologies

    Directory of Open Access Journals (Sweden)

    Muhammad Tabish Niaz

    2017-02-01

    Full Text Available Visible light communication (VLC has recently gained significant academic and industrial attention. VLC has great potential to supplement the functioning of the upcoming radio-frequency (RF-based 5G networks. It is best suited for home, office, and commercial indoor environments as it provides a high bandwidth and high data rate, and the visible light spectrum is free to use. This paper proposes a multi-user full-duplex VLC system using red-green-blue (RGB, and white emitting diodes (LEDs for smart home technologies. It utilizes red, green, and blue LEDs for downlink transmission and a simple phosphor white LED for uplink transmission. The red and green color bands are used for user data and smart devices, respectively, while the blue color band is used with the white LED for uplink transmission. The simulation was carried out to verify the performance of the proposed multi-user full-duplex VLC system. In addition to the performance evaluation, a cost-power consumption analysis was performed by comparing the power consumption and the resulting cost of the proposed VLC system to the power consumed and resulting cost of traditional Wi-Fi based systems and hybrid systems that utilized both VLC and Wi-Fi. Our findings showed that the proposed system improved the data rate and bit-error rate performance, while minimizing the power consumption and the associated costs. These results have demonstrated that a full-duplex VLC system is a feasible solution suitable for indoor environments as it provides greater cost savings and energy efficiency when compared to traditional Wi-Fi-based systems and hybrid systems that utilize both VLC and Wi-Fi.

  12. Blind Quantum Computation

    DEFF Research Database (Denmark)

    Salvail, Louis; Arrighi, Pablo

    2006-01-01

    We investigate the possibility of "having someone carry out the work of executing a function for you, but without letting him learn anything about your input". Say Alice wants Bob to compute some known function f upon her input x, but wants to prevent Bob from learning anything about x. The situa......We investigate the possibility of "having someone carry out the work of executing a function for you, but without letting him learn anything about your input". Say Alice wants Bob to compute some known function f upon her input x, but wants to prevent Bob from learning anything about x....... The situation arises for instance if client Alice has limited computational resources in comparison with mistrusted server Bob, or if x is an inherently mobile piece of data. Could there be a protocol whereby Bob is forced to compute f(x) "blindly", i.e. without observing x? We provide such a blind computation...... protocol for the class of functions which admit an efficient procedure to generate random input-output pairs, e.g. factorization. The cheat-sensitive security achieved relies only upon quantum theory being true. The security analysis carried out assumes the eavesdropper performs individual attacks....

  13. Blind Measurement Selection: A Random Matrix Theory Approach

    KAUST Repository

    Elkhalil, Khalil; Kammoun, Abla; Al-Naffouri, Tareq Y.; Alouini, Mohamed-Slim

    2016-01-01

    -aware fashions. We present two potential applications where the proposed algorithms can be used, namely antenna selection for uplink transmissions in large scale multi-user systems and sensor selection for wireless sensor networks. Numerical results are also

  14. Neuromuscular Exercise Post Partial Medial Meniscectomy

    DEFF Research Database (Denmark)

    Hall, Michelle; Hinman, Rana S; Wrigley, Tim V

    2015-01-01

    PURPOSE: To evaluate the effects of a 12-week, home-based, physiotherapist-guided neuromuscular exercise program on the knee adduction moment (an indicator of mediolateral knee load distribution) in people with a medial arthroscopic partial meniscectomy within the past 3-12 months. METHODS......: An assessor-blinded, randomised controlled trial including people aged 30-50 years with no to mild pain following medial arthroscopic partial meniscectomy was conducted. Participants were randomly allocated to either a 12-week neuromuscular exercise program that targeted neutral lower limb alignment...... or a control group with no exercise. The exercise program included eight individual sessions with one of seven physiotherapists in private clinics, together with home exercises. Primary outcomes were the peak external knee adduction moment during normal pace walking and during a one-leg sit-to-stand. Secondary...

  15. What makes an automated teller machine usable by blind users?

    Science.gov (United States)

    Manzke, J M; Egan, D H; Felix, D; Krueger, H

    1998-07-01

    Fifteen blind and sighted subjects, who featured as a control group for acceptance, were asked for their requirements for automated teller machines (ATMs). Both groups also tested the usability of a partially operational ATM mock-up. This machine was based on an existing cash dispenser, providing natural speech output, different function menus and different key arrangements. Performance and subjective evaluation data of blind and sighted subjects were collected. All blind subjects were able to operate the ATM successfully. The implemented speech output was the main usability factor for them. The different interface designs did not significantly affect performance and subjective evaluation. Nevertheless, design recommendations can be derived from the requirement assessment. The sighted subjects were rather open for design modifications, especially the implementation of speech output. However, there was also a mismatch of the requirements of the two subject groups, mainly concerning the key arrangement.

  16. POSTERIOR SEGMENT CAUSES OF BLINDNESS AMONG CHILDREN IN BLIND SCHOOLS

    Directory of Open Access Journals (Sweden)

    Sandhya

    2015-09-01

    Full Text Available BACKGROUND: It is estimated that there are 1.4 million irreversibly blind children in the world out of which 1 million are in Asia alone. India has the highest number of blind children than any other country. Nearly 70% of the childhood blindness is avoidable. There i s paucity of data available on the causes of childhood blindness. This study focuses on the posterior segment causes of blindness among children attending blind schools in 3 adjacent districts of Andhra Pradesh. MATERIAL & METHODS: This is a cross sectiona l study conducted among 204 blind children aged 6 - 16 years age. Detailed eye examination was done by the same investigator to avoid bias. Posterior segment examination was done using a direct and/or indirect ophthalmoscope after dilating pupil wherever nec essary. The standard WHO/PBL for blindness and low vision examination protocol was used to categorize the causes of blindness. A major anatomical site and underlying cause was selected for each child. The study was carried out during July 2014 to June 2015 . The results were analyzed using MS excel software and Epi - info 7 software version statistical software. RESULTS: Majority of the children was found to be aged 13 - 16 years (45.1% and males (63.7%. Family history of blindness was noted in 26.0% and consa nguinity was reported in 29.9% cases. A majority of them were belonged to fulfill WHO grade of blindness (73.0% and in majority of the cases, the onset of blindness was since birth (83.7%. The etiology of blindness was unknown in majority of cases (57.4% while hereditary causes constituted 25.4% cases. Posterior segment causes were responsible in 33.3% cases with retina being the most commonly involved anatomical site (19.1% followed by optic nerve (14.2%. CONCLUSIONS: There is a need for mandatory oph thalmic evaluation, refraction and assessment of low vision prior to admission into blind schools with periodic evaluation every 2 - 3 years

  17. Testing Children for Color Blindness

    Science.gov (United States)

    ... Stories Español Eye Health / News Testing Children for Color Blindness Leer en Español: Pruebas para Detectar Daltonismo en ... study shows that kids can be tested for color blindness as soon as age 4, finds Caucasian boys ...

  18. Culture and change blindness.

    Science.gov (United States)

    Masuda, Takahiko; Nisbett, Richard E

    2006-03-04

    Research on perception and cognition suggests that whereas East Asians view the world holistically, attending to the entire field and relations among objects, Westerners view the world analytically, focusing on the attributes of salient objects. These propositions were examined in the change-blindness paradigm. Research in that paradigm finds American participants to be more sensitive to changes in focal objects than to changes in the periphery or context. We anticipated that this would be less true for East Asians and that they would be more sensitive to context changes than would Americans. We presented participants with still photos and with animated vignettes having changes in focal object information and contextual information. Compared to Americans, East Asians were more sensitive to contextual changes than to focal object changes. These results suggest that there can be cultural variation in what may seem to be basic perceptual processes. 2006 Lawrence Erlbaum Associates, Inc.

  19. Hyperbolic partial differential equations

    CERN Document Server

    Witten, Matthew

    1986-01-01

    Hyperbolic Partial Differential Equations III is a refereed journal issue that explores the applications, theory, and/or applied methods related to hyperbolic partial differential equations, or problems arising out of hyperbolic partial differential equations, in any area of research. This journal issue is interested in all types of articles in terms of review, mini-monograph, standard study, or short communication. Some studies presented in this journal include discretization of ideal fluid dynamics in the Eulerian representation; a Riemann problem in gas dynamics with bifurcation; periodic M

  20. Successful removable partial dentures.

    Science.gov (United States)

    Lynch, Christopher D

    2012-03-01

    Removable partial dentures (RPDs) remain a mainstay of prosthodontic care for partially dentate patients. Appropriately designed, they can restore masticatory efficiency, improve aesthetics and speech, and help secure overall oral health. However, challenges remain in providing such treatments, including maintaining adequate plaque control, achieving adequate retention, and facilitating patient tolerance. The aim of this paper is to review the successful provision of RPDs. Removable partial dentures are a successful form of treatment for replacing missing teeth, and can be successfully provided with appropriate design and fabrication concepts in mind.

  1. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2011-01-01

    A rigorous, yet accessible, introduction to partial differential equations-updated in a valuable new edition Beginning Partial Differential Equations, Second Edition provides a comprehensive introduction to partial differential equations (PDEs) with a special focus on the significance of characteristics, solutions by Fourier series, integrals and transforms, properties and physical interpretations of solutions, and a transition to the modern function space approach to PDEs. With its breadth of coverage, this new edition continues to present a broad introduction to the field, while also addres

  2. Cross-Layer Framework for Multiuser Real Time H.264/AVC Video Encoding and Transmission over Block Fading MIMO Channels Using Outage Probability

    Directory of Open Access Journals (Sweden)

    Slavche Pejoski

    2014-01-01

    Full Text Available We present a framework for cross-layer optimized real time multiuser encoding of video using a single layer H.264/AVC and transmission over MIMO wireless channels. In the proposed cross-layer adaptation, the channel of every user is characterized by the probability density function of its channel mutual information and the performance of the H.264/AVC encoder is modeled by a rate distortion model that takes into account the channel errors. These models are used during the resource allocation of the available slots in a TDMA MIMO communication system with capacity achieving channel codes. This framework allows for adaptation to the statistics of the wireless channel and to the available resources in the system and utilization of the multiuser diversity of the transmitted video sequences. We show the effectiveness of the proposed framework for video transmission over Rayleigh MIMO block fading channels, when channel distribution information is available at the transmitter.

  3. Partial knee replacement - slideshow

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/presentations/100225.htm Partial knee replacement - series—Normal anatomy To use the sharing ... A.M. Editorial team. Related MedlinePlus Health Topics Knee Replacement A.D.A.M., Inc. is accredited ...

  4. Multi-user software of radio therapeutical calculation using a computational network; Software multiusuario de calculo radioterapeutico usando una red de computo

    Energy Technology Data Exchange (ETDEWEB)

    Allaucca P, J.J.; Picon C, C.; Zaharia B, M. [Departamento de Radioterapia, Instituto de Enfermedades Neoplasicas, Av. Angamos Este 2520, Lima 34 (Peru)

    1998-12-31

    It has been designed a hardware and software system for a radiotherapy Department. It runs under an Operative system platform Novell Network sharing the existing resources and of the server, it is centralized, multi-user and of greater safety. It resolves a variety of problems and calculation necessities, patient steps and administration, it is very fast and versatile, it contains a set of menus and options which may be selected with mouse, direction arrows or abbreviated keys. (Author)

  5. Beginning partial differential equations

    CERN Document Server

    O'Neil, Peter V

    2014-01-01

    A broad introduction to PDEs with an emphasis on specialized topics and applications occurring in a variety of fields Featuring a thoroughly revised presentation of topics, Beginning Partial Differential Equations, Third Edition provides a challenging, yet accessible,combination of techniques, applications, and introductory theory on the subjectof partial differential equations. The new edition offers nonstandard coverageon material including Burger's equation, the telegraph equation, damped wavemotion, and the use of characteristics to solve nonhomogeneous problems. The Third Edition is or

  6. The role of environment design in an educational Multi-User Virtual Environment

    DEFF Research Database (Denmark)

    Papachristos, Nikiforos; Vrellis, Ioannis; Natsis, Antonios

    2014-01-01

    This paper presents empirical results from an exploratory study conducted in an authentic educational situation with preservice education students enrolled in an undergraduate course, which was partially taught in Second Life. The study investigated the effect of environment design on presence, l...... necessary for all students to become familiar with the virtual environment and possible time losses due to technical issues. This study could act as support to construct and test hypotheses regarding the role of educational setting design in teaching and learning in MUVEs....

  7. The design of inclusive curricula for multi-user virtual environments: a framework for developers and educators

    Directory of Open Access Journals (Sweden)

    Denise Wood

    2011-09-01

    Full Text Available Increasing access to Information Communication Technologies and a growing awareness of the importance of digital media literacy have led many educators to seek innovative solutions to harness the enthusiasm of ‘net gen’ learners while also enhancing their ability to collaborate, communicate and problem solve augmented by digital technologies. One of the emergent trends in response to these demands has been the shift away from traditional models of teaching to more flexible approaches such as the use of multi-user virtual environments (MUVEs designed to facilitate a more collaborative and participatory approach to student learning. At the same time, international initiatives such as the United Nations Millennium Development Goals, Education for All and the United Nations Convention on the Rights of Persons with Disabilities have highlighted the importance of ensuring that such teaching and learning environments are inclusive of students with diverse needs. Many universities are also responding to a widening participation agenda; a policy focus which aims to increase both the access and success rates of students from low socio-economic backgrounds. Educational technology has long been regarded as a means by which students who may be isolated by disability, geographical location and/or social circumstances can gain access to such learning opportunities. The growth in the use of MUVEs combined with increasing access to mobile communications opens up new opportunities for engaging students from diverse backgrounds through virtual learning environments. Yet despite the potential, there are many challenges in ensuring that the very students who are most able to benefit from such e-learning technologies are not further disadvantaged by a lack of attention to both the technical and pedagogical considerations required in the design of inclusive e-learning environments. This paper reports on the findings of research funded through an Australian

  8. Overview on Deaf-Blindness

    Science.gov (United States)

    ... of Deaf-Blind Education Transition to Adulthood > Transition Self Determination Person Centered Planning Postsecondary Education Independent Living Employment Customized Employment Sex Education Adult Services Technology Personnel > Intervener Services Support ...

  9. American Foundation for the Blind

    Science.gov (United States)

    ... loss Text Size Smaller Type Larger Type Change Colors My AFB Search Donate to AFB Shop AFB ... and More Public Policy and Research Statistics on Blindness DirectConnect: Public Policy and Advocacy News Research Navigator: ...

  10. Partial differential equations

    CERN Document Server

    Evans, Lawrence C

    2010-01-01

    This text gives a comprehensive survey of modern techniques in the theoretical study of partial differential equations (PDEs) with particular emphasis on nonlinear equations. The exposition is divided into three parts: representation formulas for solutions; theory for linear partial differential equations; and theory for nonlinear partial differential equations. Included are complete treatments of the method of characteristics; energy methods within Sobolev spaces; regularity for second-order elliptic, parabolic, and hyperbolic equations; maximum principles; the multidimensional calculus of variations; viscosity solutions of Hamilton-Jacobi equations; shock waves and entropy criteria for conservation laws; and, much more.The author summarizes the relevant mathematics required to understand current research in PDEs, especially nonlinear PDEs. While he has reworked and simplified much of the classical theory (particularly the method of characteristics), he primarily emphasizes the modern interplay between funct...

  11. Simple pendulum for blind students

    Science.gov (United States)

    Goncalves, A. M. B.; Cena, C. R.; Alves, D. C. B.; Errobidart, N. C. G.; Jardim, M. I. A.; Queiros, W. P.

    2017-09-01

    Faced with the need to teach physics to the visually impaired, in this paper we propose a way to demonstrate the dependence of distance and time in a pendulum experiment to blind students. The periodic oscillation of the pendulum is translated, by an Arduino and an ultrasonic sensor, in a periodic variation of frequency in a speaker. The main advantage of this proposal is the possibility that a blind student understands the movement without necessity of touching it.

  12. Individual differences in change blindness

    OpenAIRE

    Bergmann, Katharina Verena

    2016-01-01

    The present work shows the existence of systematic individual differences in change blindness. It can be concluded that the sensitivity for changes is a trait. That is, persons differ in their ability to detect changes, independent from the situation or the measurement method. Moreover, there are two explanations for individual differences in change blindness: a) capacity differences in visual selective attention that may be influenced by top-down activated attention helping to focus attentio...

  13. Monotherapy for partial epilepsy: focus on levetiracetam

    Directory of Open Access Journals (Sweden)

    Antonio Gambardella

    2008-03-01

    Full Text Available Antonio Gambardella1,2, Angelo Labate1,2, Eleonora Colosimo1, Roberta Ambrosio1, Aldo Quattrone1,21Institute of Neurology, University Magna Græcia, Catanzaro, Italy; 2Institute of Neurological Sciences, National Research Council, Piano Lago di Mangone, Cosenza, ItalyAbstract: Levetiracetam (LEV, the S-enantiomer of alpha-ethyl-2-oxo-1-pyrollidine acetamide, is a recently licensed antiepileptic drug (AED for adjunctive therapy of partial seizures. Its mechanism of action is uncertain but it exhibits a unique profile of anticonvulsant activity in models of chronic epilepsy. Five randomized, double-blind, placebo-controlled trials enrolling adult or pediatric patients with refractory partial epilepsy have demonstrated the efficacy of LEV as adjunctive therapy, with a responder rate (≥50% reduction in seizure frequency of 28%–45%. Long-term efficacy studies suggest retention rates of 60% after one year, with 13% of patients seizure-free for 6 months of the study and 8% seizure-free for 1 year. More recent studies illustrated successful conversion to monotherapy in patients with refractory epilepsy, and its effectiveness as a single agent in partial epilepsy. LEV has also efficacy in generalized epilepsies. Adverse effects of LEV, including somnolence, lethargy, and dizziness, are generally mild and their occurrence rate seems to be not significantly different from that observed in placebo groups. LEV also has no clinically significant pharmacokinetic interactions with other AEDs, or with commonly prescribed medications. The combination of effective antiepileptic properties with a relatively mild adverse effect profile makes LEV an attractive therapy for partial seizures.Keywords: levetiracetam, partial epilepsy, antiepileptic drugs

  14. Optimization of partial search

    International Nuclear Information System (INIS)

    Korepin, Vladimir E

    2005-01-01

    A quantum Grover search algorithm can find a target item in a database faster than any classical algorithm. One can trade accuracy for speed and find a part of the database (a block) containing the target item even faster; this is partial search. A partial search algorithm was recently suggested by Grover and Radhakrishnan. Here we optimize it. Efficiency of the search algorithm is measured by the number of queries to the oracle. The author suggests a new version of the Grover-Radhakrishnan algorithm which uses a minimal number of such queries. The algorithm can run on the same hardware that is used for the usual Grover algorithm. (letter to the editor)

  15. Psychologica and social adjustment to blindness: Understanding ...

    African Journals Online (AJOL)

    Psychologica and social adjustment to blindness: Understanding from two groups of blind people in Ilorin, Nigeria. ... Background: Blindness can cause psychosocial distress leading to maladjustment if not mitigated. Maladjustment is a secondary burden that further reduces quality of life of the blind. Adjustment is often ...

  16. Blinded trials taken to the test

    DEFF Research Database (Denmark)

    Hróbjartsson, A; Forfang, E; Haahr, M T

    2007-01-01

    Blinding can reduce bias in randomized clinical trials, but blinding procedures may be unsuccessful. Our aim was to assess how often randomized clinical trials test the success of blinding, the methods involved and how often blinding is reported as being successful....

  17. The Viking viewer for connectomics: scalable multi-user annotation and summarization of large volume data sets.

    Science.gov (United States)

    Anderson, J R; Mohammed, S; Grimm, B; Jones, B W; Koshevoy, P; Tasdizen, T; Whitaker, R; Marc, R E

    2011-01-01

    Modern microscope automation permits the collection of vast amounts of continuous anatomical imagery in both two and three dimensions. These large data sets present significant challenges for data storage, access, viewing, annotation and analysis. The cost and overhead of collecting and storing the data can be extremely high. Large data sets quickly exceed an individual's capability for timely analysis and present challenges in efficiently applying transforms, if needed. Finally annotated anatomical data sets can represent a significant investment of resources and should be easily accessible to the scientific community. The Viking application was our solution created to view and annotate a 16.5 TB ultrastructural retinal connectome volume and we demonstrate its utility in reconstructing neural networks for a distinctive retinal amacrine cell class. Viking has several key features. (1) It works over the internet using HTTP and supports many concurrent users limited only by hardware. (2) It supports a multi-user, collaborative annotation strategy. (3) It cleanly demarcates viewing and analysis from data collection and hosting. (4) It is capable of applying transformations in real-time. (5) It has an easily extensible user interface, allowing addition of specialized modules without rewriting the viewer. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

  18. Physical Layer Security Enhancement in Multiuser Mixed RF#x002F;FSO Relay Networks under RF Interference

    KAUST Repository

    El-Malek, Ahmed H. Abd; Salhab, Anas M.; Zummo, Salam A.; Alouini, Mohamed-Slim

    2017-01-01

    In this paper, the impact of radio frequency (RF) co-channel interference (CCI) on the performance of multiuser (MU) mixed RF#x002F;free space optical (FSO) relay network with opportunistic user scheduling is studied. In the considered system, a user is opportunistically selected to communicate with a single destination through an amplify-and- forward (AF) relay in the presence of a single passive eavesdropper. The RF#x002F;FSO channel models are assumed to follow Rayleigh#x002F;Gamma-Gamma fading models, respectively with pointing errors and identical RF CCI signals. Exact closed-form expression for the system outage probability is derived. Then, an asymptotic expression for the outage probability is obtained at the high signal- to-interference-plus-noise ratio (SINR) regime. The asymptotic results are used to formulate a power allocation problem to obtain optimal RF transmission power. Then, the secrecy performance is studied in the presence of CCI at both the authorized relay and eavesdropper by obtaining exact and asymptotic closed-form expressions for the intercept probability. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the work.

  19. Phenology of the multi-use tree species Carapa guianensis in a floodplain forest of the Amazon Estuary

    Directory of Open Access Journals (Sweden)

    Adelson R. Dantas

    Full Text Available ABSTRACT Carapa guianensis is a multi-use tree species that is used for the production of timber and non-timber forest products (NTFPs that are used and sold by rural Amazonian populations. Here we aimed to evaluate the phenophases of C. guianensis in várzea forest and relate them to climatic seasonality. Phenophases of flowering (flower buds and open flowers, fruiting (unripe and ripe fruits, and leaf flush and leaf fall were recorded for 30 individual trees during a 25 month period. Relationships between rainfall and the proportion of trees in each phenophase were tested using Generalised Linear Models with quasi-binomial errors. Flowering was found to peak in the driest months of the year (September to December, while fruiting peaked during the wettest months of the year when river levels are at their highest (January to May. Leaf flush and leaf fall occurred simultaneously throughout the year, regardless of seasonality. Strong seasonality in flowering and fruiting of C. guianensis likely represents a reproductive strategy that maximizes pollination and hydrochorous seed dispersal. This study has the potential to aid in planning the timing of seed collection and oil extraction activities, thus contributing to the sustainable exploitation of this tree.

  20. A Chip-Level BSOR-Based Linear GSIC Multiuser Detector for Long-Code CDMA Systems

    Directory of Open Access Journals (Sweden)

    M. Benyoucef

    2008-01-01

    Full Text Available We introduce a chip-level linear group-wise successive interference cancellation (GSIC multiuser structure that is asymptotically equivalent to block successive over-relaxation (BSOR iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed. The main advantage of the proposed scheme is that it uses directly the spreading codes instead of the cross-correlation matrix and thus does not require the calculation of the cross-correlation matrix (requires 2NK2 floating point operations (flops, where N is the processing gain and K is the number of users which reduces significantly the overall computational complexity. Thus it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We study the convergence behavior of the proposed scheme using two approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is in the interval ]0, 2[. Simulation results are in excellent agreement with theory.

  1. Performance Analysis of a De-correlated Modified Code Tracking Loop for Synchronous DS-CDMA System under Multiuser Environment

    Science.gov (United States)

    Wu, Ya-Ting; Wong, Wai-Ki; Leung, Shu-Hung; Zhu, Yue-Sheng

    This paper presents the performance analysis of a De-correlated Modified Code Tracking Loop (D-MCTL) for synchronous direct-sequence code-division multiple-access (DS-CDMA) systems under multiuser environment. Previous studies have shown that the imbalance of multiple access interference (MAI) in the time lead and time lag portions of the signal causes tracking bias or instability problem in the traditional correlating tracking loop like delay lock loop (DLL) or modified code tracking loop (MCTL). In this paper, we exploit the de-correlating technique to combat the MAI at the on-time code position of the MCTL. Unlike applying the same technique to DLL which requires an extensive search algorithm to compensate the noise imbalance which may introduce small tracking bias under low signal-to-noise ratio (SNR), the proposed D-MCTL has much lower computational complexity and exhibits zero tracking bias for the whole range of SNR, regardless of the number of interfering users. Furthermore, performance analysis and simulations based on Gold codes show that the proposed scheme has better mean square tracking error, mean-time-to-lose-lock and near-far resistance than the other tracking schemes, including traditional DLL (T-DLL), traditional MCTL (T-MCTL) and modified de-correlated DLL (MD-DLL).

  2. A Chip-Level BSOR-Based Linear GSIC Multiuser Detector for Long-Code CDMA Systems

    Directory of Open Access Journals (Sweden)

    Benyoucef M

    2007-01-01

    Full Text Available We introduce a chip-level linear group-wise successive interference cancellation (GSIC multiuser structure that is asymptotically equivalent to block successive over-relaxation (BSOR iteration, which is known to outperform the conventional block Gauss-Seidel iteration by an order of magnitude in terms of convergence speed. The main advantage of the proposed scheme is that it uses directly the spreading codes instead of the cross-correlation matrix and thus does not require the calculation of the cross-correlation matrix (requires floating point operations (flops, where is the processing gain and is the number of users which reduces significantly the overall computational complexity. Thus it is suitable for long-code CDMA systems such as IS-95 and UMTS where the cross-correlation matrix is changing every symbol. We study the convergence behavior of the proposed scheme using two approaches and prove that it converges to the decorrelator detector if the over-relaxation factor is in the interval ]0, 2[. Simulation results are in excellent agreement with theory.

  3. Protocol Design and Performance Analysis of Multiuser Mixed RF and Hybrid FSO/RF Relaying With Buffers

    KAUST Repository

    Al-Eryani, Yasser F.

    2018-03-07

    In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users\\' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay\\'s buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.

  4. Public Auditing with Privacy Protection in a Multi-User Model of Cloud-Assisted Body Sensor Networks

    Science.gov (United States)

    Li, Song; Cui, Jie; Zhong, Hong; Liu, Lu

    2017-01-01

    Wireless Body Sensor Networks (WBSNs) are gaining importance in the era of the Internet of Things (IoT). The modern medical system is a particular area where the WBSN techniques are being increasingly adopted for various fundamental operations. Despite such increasing deployments of WBSNs, issues such as the infancy in the size, capabilities and limited data processing capacities of the sensor devices restrain their adoption in resource-demanding applications. Though providing computing and storage supplements from cloud servers can potentially enrich the capabilities of the WBSNs devices, data security is one of the prevailing issues that affects the reliability of cloud-assisted services. Sensitive applications such as modern medical systems demand assurance of the privacy of the users’ medical records stored in distant cloud servers. Since it is economically impossible to set up private cloud servers for every client, auditing data security managed in the remote servers has necessarily become an integral requirement of WBSNs’ applications relying on public cloud servers. To this end, this paper proposes a novel certificateless public auditing scheme with integrated privacy protection. The multi-user model in our scheme supports groups of users to store and share data, thus exhibiting the potential for WBSNs’ deployments within community environments. Furthermore, our scheme enriches user experiences by offering public verifiability, forward security mechanisms and revocation of illegal group members. Experimental evaluations demonstrate the security effectiveness of our proposed scheme under the Random Oracle Model (ROM) by outperforming existing cloud-assisted WBSN models. PMID:28475110

  5. Public Auditing with Privacy Protection in a Multi-User Model of Cloud-Assisted Body Sensor Networks.

    Science.gov (United States)

    Li, Song; Cui, Jie; Zhong, Hong; Liu, Lu

    2017-05-05

    Wireless Body Sensor Networks (WBSNs) are gaining importance in the era of the Internet of Things (IoT). The modern medical system is a particular area where the WBSN techniques are being increasingly adopted for various fundamental operations. Despite such increasing deployments of WBSNs, issues such as the infancy in the size, capabilities and limited data processing capacities of the sensor devices restrain their adoption in resource-demanding applications. Though providing computing and storage supplements from cloud servers can potentially enrich the capabilities of the WBSNs devices, data security is one of the prevailing issues that affects the reliability of cloud-assisted services. Sensitive applications such as modern medical systems demand assurance of the privacy of the users' medical records stored in distant cloud servers. Since it is economically impossible to set up private cloud servers for every client, auditing data security managed in the remote servers has necessarily become an integral requirement of WBSNs' applications relying on public cloud servers. To this end, this paper proposes a novel certificateless public auditing scheme with integrated privacy protection. The multi-user model in our scheme supports groups of users to store and share data, thus exhibiting the potential for WBSNs' deployments within community environments. Furthermore, our scheme enriches user experiences by offering public verifiability, forward security mechanisms and revocation of illegal group members. Experimental evaluations demonstrate the security effectiveness of our proposed scheme under the Random Oracle Model (ROM) by outperforming existing cloud-assisted WBSN models.

  6. Security-Reliability Trade-Off Analysis for Multiuser SIMO Mixed RF/FSO Relay Networks With Opportunistic User Scheduling

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2016-05-24

    In this paper, we study the performance of multiuser single-input multiple-output mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling. The considered system includes multiple users, one amplify-and-forward relay, one destination, and a multiple-antenna eavesdropper. The users are connected with the relay node through RF links and the relay is connected with the destination through an FSO link. Both maximum ratio combining and selection combining schemes are used at the multiple-antenna relay to combine the signal received from the best user on different antennas. The RF/FSO channels models are assumed to follow Nakagami-m/gamma-gamma fading models with pointing errors. Closed-form expressions are derived for the outage probability, average symbol error probability, and ergodic channel capacity. Then, the power of the selected best user is determined to minimize the system asymptotic outage probability under the dominant RF or FSO link. Then, the considered system secrecy performance is investigated, where the closed-form expressions for the intercept probability are derived. Finally, we propose a new cooperative jamming model in which the worst user is selected by the authorized system to jam the existing eavesdropper. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

  7. Physical Layer Security Enhancement in Multiuser Mixed RF#x002F;FSO Relay Networks under RF Interference

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2017-05-12

    In this paper, the impact of radio frequency (RF) co-channel interference (CCI) on the performance of multiuser (MU) mixed RF#x002F;free space optical (FSO) relay network with opportunistic user scheduling is studied. In the considered system, a user is opportunistically selected to communicate with a single destination through an amplify-and- forward (AF) relay in the presence of a single passive eavesdropper. The RF#x002F;FSO channel models are assumed to follow Rayleigh#x002F;Gamma-Gamma fading models, respectively with pointing errors and identical RF CCI signals. Exact closed-form expression for the system outage probability is derived. Then, an asymptotic expression for the outage probability is obtained at the high signal- to-interference-plus-noise ratio (SINR) regime. The asymptotic results are used to formulate a power allocation problem to obtain optimal RF transmission power. Then, the secrecy performance is studied in the presence of CCI at both the authorized relay and eavesdropper by obtaining exact and asymptotic closed-form expressions for the intercept probability. The derived analytical formulas herein are supported by numerical and simulation results to clarify the main contributions of the work.

  8. Development of a Multi-User Polyimide-MEMS Fabrication Process and its Application to MicroHotplates

    KAUST Repository

    Lizardo, Ernesto B.

    2013-05-08

    Micro-electro-mechanical systems (MEMS) became possible thanks to the silicon based technology used to fabricate integrated circuits. Originally, MEMS fabrication was limited to silicon based techniques and materials, but the expansion of MEMS applications brought the need of a wider catalog of materials, including polymers, now being used to fabricate MEMS. Polyimide is a very attractive polymer for MEMS fabrication due to its high temperature stability compared to other polymers, low coefficient of thermal expansion, low film stress and low cost. The goal of this thesis is to expand the Polyimide usage as structural material for MEMS by the development of a multi-user fabrication process for the integration of this polymer along with multiple metal layers on a silicon substrate. The process also integrates amorphous silicon as sacrificial layer to create free-standing structures. Dry etching is used to release the devices and avoid stiction phenomena. The developed process is used to fabricate platforms for micro-hotplate gas sensors. The fabrication steps for the platforms are described in detail, explaining the process specifics and capabilities. An initial testing of the micro-hotplate is presented. As the process was also used as educational tool, some designs made by students and fabricated with the Polyimide-MEMS process are also presented.

  9. Protocol Design and Performance Analysis of Multiuser Mixed RF and Hybrid FSO/RF Relaying With Buffers

    KAUST Repository

    Al-Eryani, Yasser F.; Salhab, Anas; Zummo, Salam A.; Alouini, Mohamed-Slim

    2018-01-01

    In this paper, a multiuser mixed radio frequency (RF) and hybrid free-space optical (FSO)/RF system is considered, where multiple mobile users transmit their data to an intermediate decode-and-forward relay node through RF links using a virtual multiple-input multipleoutput (MIMO) system, and the relay node forwards the multiplexed data of all users through a FSO link that is supported by a RF MIMO backup system to the destination. The relay node is equipped with a buffer in the physical layer for temporal storage of the users' data until the best channel conditions at the relay-destination link aremet. For this communication setup, we first propose a transmission protocol that achieves a multiplexing gain through a virtual MIMO system. After that, we derive closed-form expressions for the end-to-end outage probability, asymptotic outage probability, average symbol error rate, and the ergodic capacity when considering the delay-tolerant (finite buffer size) scenario. The results show that buffering in the physical layer provides a significant enhancement to the system performance (outage, error rate, and ergodic capacity). It is also found that pointing error and severe weather turbulence conditions become more tolerable with the existence of the relay's buffer and RF backup link (in the second hop). In addition, the proposed virtual MIMO scheme shows a significant performance enhancement at a high number of receiving antennas, which introduces potential lowcomplexity diversity gain-based massive MIMO schemes.

  10. Enhancing Physical Layer Security of Multiuser SIMO Mixed RF/FSO Relay Networks with Multi-Eavesdroppers

    KAUST Repository

    El-Malek, Ahmed H. Abd

    2017-02-09

    In this paper, we investigate the secrecy performance of multiuser (MU) single-input multiple-output (SIMO) mixed radio frequency (RF)/free space optical (FSO) relay network with opportunistic user scheduling and multiple eavesdropping attacks. The considered system includes multiple users, one amplify-and-froward (AF) relay, one destination and multiple eavesdroppers. The users are connected with a multi-antenna relay through RF links and the relay is connected with the destination through an FSO link. Maximal ratio combining (MRC) scheme is used at the relay node to combine the received signals at its different antennas. The RF/FSO channels are assumed to follow Nakagami-m/Gamma-Gamma fading models with considering the effect of pointing errors. In particular, we derive closed- form expressions for the exact and asymptotic outage probabilities. The asymptotic outage results are then used to obtain the optimal RF transmission power based on the dominant link between the RF and FSO links. Then, the considered system secrecy performance is investigated in the presence of multi- eavesdroppers where exact closed-form expression for the intercept probability is derived. Finally, a cooperative jamming model is proposed along with power allocation to enhance the system secrecy performance. Monte-Carlo simulations are provided to validate the achieved exact and asymptotic results.

  11. Causes of blindness in blind unit of the school for the handicapped ...

    African Journals Online (AJOL)

    To describe the causes of blindness in pupils and staff in the blind unit of the School for the Handicapped in Kwara State. 2. To identify problems in the blind school and initiate intervention. All the blind or visually challenged people in the blind unit of the school for the handicapped were interviewed and examined using a ...

  12. Auxiliary partial liver transplantation

    NARCIS (Netherlands)

    C.B. Reuvers (Cornelis Bastiaan)

    1986-01-01

    textabstractIn this thesis studies on auxiliary partial liver transplantation in the dog and the pig are reported. The motive to perform this study was the fact that patients with acute hepatic failure or end-stage chronic liver disease are often considered to form too great a risk for successful

  13. Partial Remission Definition

    DEFF Research Database (Denmark)

    Andersen, Marie Louise Max; Hougaard, Philip; Pörksen, Sven

    2014-01-01

    OBJECTIVE: To validate the partial remission (PR) definition based on insulin dose-adjusted HbA1c (IDAA1c). SUBJECTS AND METHODS: The IDAA1c was developed using data in 251 children from the European Hvidoere cohort. For validation, 129 children from a Danish cohort were followed from the onset...

  14. Fundamental partial compositeness

    DEFF Research Database (Denmark)

    Sannino, Francesco; Strumia, Alessandro; Tesi, Andrea

    2016-01-01

    We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Unde...

  15. Partially ordered models

    NARCIS (Netherlands)

    Fernandez, R.; Deveaux, V.

    2010-01-01

    We provide a formal definition and study the basic properties of partially ordered chains (POC). These systems were proposed to model textures in image processing and to represent independence relations between random variables in statistics (in the later case they are known as Bayesian networks).

  16. Partially Hidden Markov Models

    DEFF Research Database (Denmark)

    Forchhammer, Søren Otto; Rissanen, Jorma

    1996-01-01

    Partially Hidden Markov Models (PHMM) are introduced. They differ from the ordinary HMM's in that both the transition probabilities of the hidden states and the output probabilities are conditioned on past observations. As an illustration they are applied to black and white image compression where...

  17. Honesty in partial logic

    NARCIS (Netherlands)

    W. van der Hoek (Wiebe); J.O.M. Jaspars; E. Thijsse

    1995-01-01

    textabstractWe propose an epistemic logic in which knowledge is fully introspective and implies truth, although truth need not imply epistemic possibility. The logic is presented in sequential format and is interpreted in a natural class of partial models, called balloon models. We examine the

  18. Algebraic partial Boolean algebras

    International Nuclear Information System (INIS)

    Smith, Derek

    2003-01-01

    Partial Boolean algebras, first studied by Kochen and Specker in the 1960s, provide the structure for Bell-Kochen-Specker theorems which deny the existence of non-contextual hidden variable theories. In this paper, we study partial Boolean algebras which are 'algebraic' in the sense that their elements have coordinates in an algebraic number field. Several of these algebras have been discussed recently in a debate on the validity of Bell-Kochen-Specker theorems in the context of finite precision measurements. The main result of this paper is that every algebraic finitely-generated partial Boolean algebra B(T) is finite when the underlying space H is three-dimensional, answering a question of Kochen and showing that Conway and Kochen's infinite algebraic partial Boolean algebra has minimum dimension. This result contrasts the existence of an infinite (non-algebraic) B(T) generated by eight elements in an abstract orthomodular lattice of height 3. We then initiate a study of higher-dimensional algebraic partial Boolean algebras. First, we describe a restriction on the determinants of the elements of B(T) that are generated by a given set T. We then show that when the generating set T consists of the rays spanning the minimal vectors in a real irreducible root lattice, B(T) is infinite just if that root lattice has an A 5 sublattice. Finally, we characterize the rays of B(T) when T consists of the rays spanning the minimal vectors of the root lattice E 8

  19. Scheduling for Multiuser MIMO Downlink Channels with Ranking-Based Feedback

    Science.gov (United States)

    Kountouris, Marios; Sälzer, Thomas; Gesbert, David

    2008-12-01

    We consider a multi-antenna broadcast channel with more single-antenna receivers than transmit antennas and partial channel state information at the transmitter (CSIT). We propose a novel type of CSIT representation for the purpose of user selection, coined as ranking-based feedback. Each user calculates and feeds back the rank, an integer between 1 and W + 1, of its instantaneous channel quality information (CQI) among a set of W past CQI measurements. Apart from reducing significantly the required feedback load, ranking-based feedback enables the transmitter to select users that are on the highest peak (quantile) with respect to their own channel distribution, independently of the distribution of other users. It can also be shown that this feedback metric can restore temporal fairness in heterogeneous networks, in which users' channels are not identically distributed and mobile terminals experience different average signal-to-noise ratio (SNR). The performance of a system that performs user selection using ranking-based CSIT in the context of random opportunistic beamforming is analyzed, and we provide design guidelines on the number of required past CSIT samples and the impact of finite W on average throughput. Simulation results show that feedback reduction of order of 40-50% can be achieved with negligible decrease in system throughput.

  20. Future trends in global blindness

    Directory of Open Access Journals (Sweden)

    Serge Resnikoff

    2012-01-01

    Full Text Available The objective of this review is to discuss the available data on the prevalence and causes of global blindness, and some of the associated trends and limitations seen. A literature search was conducted using the terms "global AND blindness" and "global AND vision AND impairment", resulting in seven appropriate articles for this review. Since 1990 the estimate of global prevalence of blindness has gradually decreased when considering the best corrected visual acuity definition: 0.71% in 1990, 0.59% in 2002, and 0.55% in 2010, corresponding to a 0.73% reduction per year over the 2002-2010 period. Significant limitations were found in the comparability between the global estimates in prevalence or causes of blindness or visual impairment. These limitations arise from various factors such as uncertainties about the true cause of the impairment, the use of different definitions and methods, and the absence of data from a number of geographical areas, leading to various extrapolation methods, which in turn seriously limit comparability. Seminal to this discussion on limitations in the comparability of studies and data, is that blindness has historically been defined using best corrected visual acuity.

  1. [Aiming for zero blindness].

    Science.gov (United States)

    Nakazawa, Toru

    2015-03-01

    Glaucoma is the leading cause of acquired blindness in Japan. One reason that it often leads to blindness is that it can continue to worsen even after effective medical reduction of intraocular pressure (IOP), the only evidence-based treatment. The limitations of current treatments make it critical to identify IOP-independent factors that can cause glaucoma and develop new drugs to target these factors. This is a challenging task, as the pathology of glaucoma is thought to be very complex, with different combinations of factors underlying its development and progression in different patients. Additionally, there is a deficiency in methods to efficiently perform clinical evaluations and reliably probe the state of the disease over relatively short periods. In addition, newly developed drugs need to be evaluated with clinical trials, for which human and financial resources are limited, before they can be widely used for treatment. Taking all these issues into consideration, it is evident that there are two urgent issues to consider: the development of methods to classify glaucoma in detail based on its pathology, and the improvement of clinical evaluation methods. In this review, we discuss some of our efforts to develop new neuroprotective agents for glaucoma, with a focus on the following three areas: 1. Clinical research and development of methods to classify glaucoma in detail based on IOP-independent factors, and the exploration of possibilities for the improvement of clinical evaluation of glaucoma. 2. Pathology-based research and development of new drugs for glaucoma, focusing on comprehensive gene expression analysis and the development of molecule-targeting drugs, using murine optic nerve crush as a disease model. 3. Development of next generation in vivo imaging modalities and the establishment of infrastructure enabling "big-data" analysis. First, we discuss our clinical research and the development of methods to classify glaucoma in detail based on IOP

  2. Partially composite Higgs models

    DEFF Research Database (Denmark)

    Alanne, Tommi; Buarque Franzosi, Diogo; Frandsen, Mads T.

    2018-01-01

    We study the phenomenology of partially composite-Higgs models where electroweak symmetry breaking is dynamically induced, and the Higgs is a mixture of a composite and an elementary state. The models considered have explicit realizations in terms of gauge-Yukawa theories with new strongly...... interacting fermions coupled to elementary scalars and allow for a very SM-like Higgs state. We study constraints on their parameter spaces from vacuum stability and perturbativity as well as from LHC results and find that requiring vacuum stability up to the compositeness scale already imposes relevant...... constraints. A small part of parameter space around the classically conformal limit is stable up to the Planck scale. This is however already strongly disfavored by LHC results. in different limits, the models realize both (partially) composite-Higgs and (bosonic) technicolor models and a dynamical extension...

  3. Arthroscopic partial medial meniscectomy

    Directory of Open Access Journals (Sweden)

    Dašić Žarko

    2011-01-01

    Full Text Available Background/Aim. Meniscal injuries are common in professional or recreational sports as well as in daily activities. If meniscal lesions lead to physical impairment they usually require surgical treatment. Arthroscopic treatment of meniscal injuries is one of the most often performed orthopedic operative procedures. Methods. The study analyzed the results of arthroscopic partial medial meniscectomy in 213 patients in a 24-month period, from 2006, to 2008. Results. In our series of arthroscopically treated medial meniscus tears we noted 78 (36.62% vertical complete bucket handle lesions, 19 (8.92% vertical incomplete lesions, 18 (8.45% longitudinal tears, 35 (16.43% oblique tears, 18 (8.45% complex degenerative lesions, 17 (7.98% radial lesions and 28 (13.14% horisontal lesions. Mean preoperative International Knee Documentation Committee (IKDC score was 49.81%, 1 month after the arthroscopic partial medial meniscectomy the mean IKDC score was 84.08%, and 6 months after mean IKDC score was 90.36%. Six months after the procedure 197 (92.49% of patients had good or excellent subjective postoperative clinical outcomes, while 14 (6.57% patients subjectively did not notice a significant improvement after the intervention, and 2 (0.93% patients had no subjective improvement after the partial medial meniscectomy at all. Conclusion. Arthroscopic partial medial meniscetomy is minimally invasive diagnostic and therapeutic procedure and in well selected cases is a method of choice for treatment of medial meniscus injuries when repair techniques are not a viable option. It has small rate of complications, low morbidity and fast rehabilitation.

  4. Space-Time Coded MC-CDMA: Blind Channel Estimation, Identifiability, and Receiver Design

    Directory of Open Access Journals (Sweden)

    Li Hongbin

    2002-01-01

    Full Text Available Integrating the strengths of multicarrier (MC modulation and code division multiple access (CDMA, MC-CDMA systems are of great interest for future broadband transmissions. This paper considers the problem of channel identification and signal combining/detection schemes for MC-CDMA systems equipped with multiple transmit antennas and space-time (ST coding. In particular, a subspace based blind channel identification algorithm is presented. Identifiability conditions are examined and specified which guarantee unique and perfect (up to a scalar channel estimation when knowledge of the noise subspace is available. Several popular single-user based signal combining schemes, namely the maximum ratio combining (MRC and the equal gain combining (EGC, which are often utilized in conventional single-transmit-antenna based MC-CDMA systems, are extended to the current ST-coded MC-CDMA (STC-MC-CDMA system to perform joint combining and decoding. In addition, a linear multiuser minimum mean-squared error (MMSE detection scheme is also presented, which is shown to outperform the MRC and EGC at some increased computational complexity. Numerical examples are presented to evaluate and compare the proposed channel identification and signal detection/combining techniques.

  5. Blind Synchronization in Asynchronous UWB Networks Based on the Transmit-Reference Scheme

    Directory of Open Access Journals (Sweden)

    Leus Geert

    2006-01-01

    Full Text Available Ultra-wideband (UWB wireless communication systems are based on the transmission of extremely narrow pulses, with a duration inferior to a nanosecond. The application of transmit reference (TR to UWB systems allows to side-step channel estimation at the receiver, with a tradeoff of the effective transmission bandwidth, which is reduced by the usage of a reference pulse. Similar to CDMA systems, different users can share the same available bandwidth by means of different spreading codes. This allows the receiver to separate users, and to recover the timing information of the transmitted data packets. The nature of UWB transmissions—short, burst-like packets—requires a fast synchronization algorithm, that can accommodate several asynchronous users. Exploiting the fact that a shift in time corresponds to a phase rotation in the frequency domain, a blind and computationally effcient synchronization algorithm that takes advantage of the shift invariance structure in the frequency domain is proposed in this paper. Integer and fractional delay estimations are considered, along with a subsequent symbol estimation step. This results in a collision-avoiding multiuser algorithm, readily applicable to a fast acquisition procedure in a UWB ad hoc network.

  6. Hierarchical partial order ranking

    International Nuclear Information System (INIS)

    Carlsen, Lars

    2008-01-01

    Assessing the potential impact on environmental and human health from the production and use of chemicals or from polluted sites involves a multi-criteria evaluation scheme. A priori several parameters are to address, e.g., production tonnage, specific release scenarios, geographical and site-specific factors in addition to various substance dependent parameters. Further socio-economic factors may be taken into consideration. The number of parameters to be included may well appear to be prohibitive for developing a sensible model. The study introduces hierarchical partial order ranking (HPOR) that remedies this problem. By HPOR the original parameters are initially grouped based on their mutual connection and a set of meta-descriptors is derived representing the ranking corresponding to the single groups of descriptors, respectively. A second partial order ranking is carried out based on the meta-descriptors, the final ranking being disclosed though average ranks. An illustrative example on the prioritisation of polluted sites is given. - Hierarchical partial order ranking of polluted sites has been developed for prioritization based on a large number of parameters

  7. New treatments of hereditary blindness

    DEFF Research Database (Denmark)

    Bertelsen, Mette; Rosenberg, Thomas; Larsen, Michael

    2013-01-01

    Ongoing clinical trials are targeting several previously intractable hereditary causes of blindness of congenital, childhood or early adulthood onset, mainly in the optic nerve and retina. The intended stage of initiation of the new therapeutic approaches ranges from neonatal life and a structura......Ongoing clinical trials are targeting several previously intractable hereditary causes of blindness of congenital, childhood or early adulthood onset, mainly in the optic nerve and retina. The intended stage of initiation of the new therapeutic approaches ranges from neonatal life...... and a structurally intact retinal tissue to adult life with a complete loss of photoreceptors. It must be assumed that some of the trials will succeed in producing new therapies and action must be taken to refine and accelerate diagnostics and to preserve therapeutic potential in blind people....

  8. Working memory and inattentional blindness.

    Science.gov (United States)

    Bredemeier, Keith; Simons, Daniel J

    2012-04-01

    Individual differences in working memory predict many aspects of cognitive performance, especially for tasks that demand focused attention. One negative consequence of focused attention is inattentional blindness, the failure to notice unexpected objects when attention is engaged elsewhere. Yet, the relationship between individual differences in working memory and inattentional blindness is unclear; some studies have found that higher working memory capacity is associated with greater noticing, but others have found no direct association. Given the theoretical and practical significance of such individual differences, more definitive tests are needed. In two studies with large samples, we tested the relationship between multiple working memory measures and inattentional blindness. Individual differences in working memory predicted the ability to perform an attention-demanding tracking task, but did not predict the likelihood of noticing an unexpected object present during the task. We discuss the reasons why we might not expect such individual differences in noticing and why other studies may have found them.

  9. 20 CFR 416.983 - How we evaluate statutory blindness.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false How we evaluate statutory blindness. 416.983... AGED, BLIND, AND DISABLED Determining Disability and Blindness Blindness § 416.983 How we evaluate statutory blindness. We will find that you are blind if you are statutorily blind within the meaning of...

  10. 20 CFR 416.982 - Blindness under a State plan.

    Science.gov (United States)

    2010-04-01

    ... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Blindness under a State plan. 416.982 Section..., BLIND, AND DISABLED Determining Disability and Blindness Blindness § 416.982 Blindness under a State... plan because of your blindness for the month of December 1973; and (c) You continue to be blind as...

  11. A hardware and software architecture to deal with multimodal and collaborative interactions in multiuser virtual reality environments

    Science.gov (United States)

    Martin, P.; Tseu, A.; Férey, N.; Touraine, D.; Bourdot, P.

    2014-02-01

    Most advanced immersive devices provide collaborative environment within several users have their distinct head-tracked stereoscopic point of view. Combining with common used interactive features such as voice and gesture recognition, 3D mouse, haptic feedback, and spatialized audio rendering, these environments should faithfully reproduce a real context. However, even if many studies have been carried out on multimodal systems, we are far to definitively solve the issue of multimodal fusion, which consists in merging multimodal events coming from users and devices, into interpretable commands performed by the application. Multimodality and collaboration was often studied separately, despite of the fact that these two aspects share interesting similarities. We discuss how we address this problem, thought the design and implementation of a supervisor that is able to deal with both multimodal fusion and collaborative aspects. The aim of this supervisor is to ensure the merge of user's input from virtual reality devices in order to control immersive multi-user applications. We deal with this problem according to a practical point of view, because the main requirements of this supervisor was defined according to a industrial task proposed by our automotive partner, that as to be performed with multimodal and collaborative interactions in a co-located multi-user environment. In this task, two co-located workers of a virtual assembly chain has to cooperate to insert a seat into the bodywork of a car, using haptic devices to feel collision and to manipulate objects, combining speech recognition and two hands gesture recognition as multimodal instructions. Besides the architectural aspect of this supervisor, we described how we ensure the modularity of our solution that could apply on different virtual reality platforms, interactive contexts and virtual contents. A virtual context observer included in this supervisor in was especially designed to be independent to the

  12. Epidemiology of blindness in children.

    Science.gov (United States)

    Solebo, Ameenat Lola; Teoh, Lucinda; Rahi, Jugnoo

    2017-09-01

    An estimated 14 million of the world's children are blind. A blind child is more likely to live in socioeconomic deprivation, to be more frequently hospitalised during childhood and to die in childhood than a child not living with blindness. This update of a previous review on childhood visual impairment focuses on emerging therapies for children with severe visual disability (severe visual impairment and blindness or SVI/BL).For children in higher income countries, cerebral visual impairment and optic nerve anomalies remain the most common causes of SVI/BL, while retinopathy of prematurity (ROP) and cataract are now the most common avoidable causes. The constellation of causes of childhood blindness in lower income settings is shifting from infective and nutritional corneal opacities and congenital anomalies to more resemble the patterns seen in higher income settings. Improvements in maternal and neonatal health and investment in and maintenance of national ophthalmic care infrastructure are the key to reducing the burden of avoidable blindness. New therapeutic targets are emerging for childhood visual disorders, although the safety and efficacy of novel therapies for diseases such as ROP or retinal dystrophies are not yet clear. Population-based epidemiological research, particularly on cerebral visual impairment and optic nerve hypoplasia, is needed in order to improve understanding of risk factors and to inform and support the development of novel therapies for disorders currently considered 'untreatable'. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. A Web-based Multi-user Interactive Visualization System For Large-Scale Computing Using Google Web Toolkit Technology

    Science.gov (United States)

    Weiss, R. M.; McLane, J. C.; Yuen, D. A.; Wang, S.

    2009-12-01

    We have created a web-based, interactive system for multi-user collaborative visualization of large data sets (on the order of terabytes) that allows users in geographically disparate locations to simultaneous and collectively visualize large data sets over the Internet. By leveraging asynchronous java and XML (AJAX) web development paradigms via the Google Web Toolkit (http://code.google.com/webtoolkit/), we are able to provide remote, web-based users a web portal to LCSE's (http://www.lcse.umn.edu) large-scale interactive visualization system already in place at the University of Minnesota that provides high resolution visualizations to the order of 15 million pixels by Megan Damon. In the current version of our software, we have implemented a new, highly extensible back-end framework built around HTTP "server push" technology to provide a rich collaborative environment and a smooth end-user experience. Furthermore, the web application is accessible via a variety of devices including netbooks, iPhones, and other web- and javascript-enabled cell phones. New features in the current version include: the ability for (1) users to launch multiple visualizations, (2) a user to invite one or more other users to view their visualization in real-time (multiple observers), (3) users to delegate control aspects of the visualization to others (multiple controllers) , and (4) engage in collaborative chat and instant messaging with other users within the user interface of the web application. We will explain choices made regarding implementation, overall system architecture and method of operation, and the benefits of an extensible, modular design. We will also discuss future goals, features, and our plans for increasing scalability of the system which includes a discussion of the benefits potentially afforded us by a migration of server-side components to the Google Application Engine (http://code.google.com/appengine/).

  14. Non-sectarian scenario experiments in socio-ecological knowledge building for multi-use marine environments: Insights from New Zealand's Marine Futures project

    KAUST Repository

    Le Heron, Richard

    2016-01-29

    The challenges of managing marine ecosystems for multiple users, while well recognised, has not led to clear strategies, principles or practice. The paper uses novel workshop based thought-experiments to address these concerns. These took the form of trans-disciplinary Non-Sectarian Scenario Experiments (NSSE), involving participants who agreed to put aside their disciplinary interests and commercial and institutional obligations. The NSSE form of co-production of knowledge is a distinctive addition to the participatory and scenario literatures in marine resource management (MRM). Set in the context of resource use conflicts in New Zealand, the workshops assembled diverse participants in the marine economy to co-develop and co-explore the making of socio-ecological knowledge and identify capability required for a new generation of multi-use oriented resource management. The thought-experiments assumed that non-sectarian navigation of scenarios will resource a step-change in marine management by facilitating new connections, relationships, and understandings of potential marine futures. Two questions guided workshop interactions: what science needs spring from pursuing imaginable possibilities and directions in a field of scenarios, and what kinds of institutions would aid the generation of science knowledge, and it application to policy and management solutions. The effectiveness of the thought- experiments helped identify ways of dealing with core problems in multi-use marine management, such as the urgent need to cope with ecological and socio-economic surprise, and define and address cumulative impacts. Discussion focuses on how the workshops offered fresh perspectives and insights into a number of challenges. These challenges include building relations of trust and collective organisation, showing the importance of values-means-ends pathways, developing facilitative legislation to enable initiatives, and the utility of the NSSEs in informing new governance and

  15. Sound lateralization test in adolescent blind individuals.

    Science.gov (United States)

    Yabe, Takao; Kaga, Kimitaka

    2005-06-21

    Blind individuals require to compensate for the lack of visual information by other sensory inputs. In particular, auditory inputs are crucial to such individuals. To investigate whether blind individuals localize sound in space better than sighted individuals, we tested the auditory ability of adolescent blind individuals using a sound lateralization method. The interaural time difference discrimination thresholds of blind individuals were statistically significantly shorter than those of blind individuals with residual vision and controls. These findings suggest that blind individuals have better auditory spatial ability than individuals with visual cues; therefore, some perceptual compensation occurred in the former.

  16. Performances of Hybrid Amplitude Shape Modulation for UWB Communications Systems over AWGN Channel in a Single and Multi-User Environment

    Directory of Open Access Journals (Sweden)

    M. Herceg

    2009-09-01

    Full Text Available This paper analyzes the performance of the hybrid Amplitude Shape Modulation (h-ASM scheme for the time-hopping ultra-wideband (TH-UWB communication systems in the single and multi-user environment. h-ASM is the combination of Pulse Amplitude Modulation (PAM and Pulse Shape Modulation (PSM based on modified Hermite pulses (MHP. This scheme is suitable for high rate data transmission applications because b = log2(MN bits can be mapped with one waveform. The channel capacity and error probability over AWGN channel are derived and compared with other modulation schemes.

  17. Socio-Emotional Effects of the Transition from Sight to Blindness

    Science.gov (United States)

    Thurston, Mhairi; Thurston, Allen; McLeod, John

    2010-01-01

    The research examined the socio-emotional impact of sight loss on a sample of 18 blind and partially sighted adults from the east coast of Scotland (average age 64). The impact of sight loss in four core areas (mood, self-concept, social connectedness and loss) was explored. Data were collected using the mental health and social functioning…

  18. The Ability to Assume the Upright Position in Blind and Sighted Children.

    Science.gov (United States)

    Gipsman, Sandra Curtis

    To investigate the ability of 48 blind and partially sighted children (8 to 10 and 12 to 14 years old) to assume the upright position, Ss were given six trials in which they were requested to move themselves from a tilted starting position in a specially constructed chair to an upright position. No significant differences were found between three…

  19. Partially ordered algebraic systems

    CERN Document Server

    Fuchs, Laszlo

    2011-01-01

    Originally published in an important series of books on pure and applied mathematics, this monograph by a distinguished mathematician explores a high-level area in algebra. It constitutes the first systematic summary of research concerning partially ordered groups, semigroups, rings, and fields. The self-contained treatment features numerous problems, complete proofs, a detailed bibliography, and indexes. It presumes some knowledge of abstract algebra, providing necessary background and references where appropriate. This inexpensive edition of a hard-to-find systematic survey will fill a gap i

  20. Infinite partial summations

    International Nuclear Information System (INIS)

    Sprung, D.W.L.

    1975-01-01

    This paper is a brief review of those aspects of the effective interaction problem that can be grouped under the heading of infinite partial summations of the perturbation series. After a brief mention of the classic examples of infinite summations, the author turns to the effective interaction problem for two extra core particles. Their direct interaction is summed to produce the G matrix, while their indirect interaction through the core is summed in a variety of ways under the heading of core polarization. (orig./WL) [de

  1. On universal partial words

    OpenAIRE

    Chen, Herman Z. Q.; Kitaev, Sergey; Mütze, Torsten; Sun, Brian Y.

    2016-01-01

    A universal word for a finite alphabet $A$ and some integer $n\\geq 1$ is a word over $A$ such that every word in $A^n$ appears exactly once as a subword (cyclically or linearly). It is well-known and easy to prove that universal words exist for any $A$ and $n$. In this work we initiate the systematic study of universal partial words. These are words that in addition to the letters from $A$ may contain an arbitrary number of occurrences of a special `joker' symbol $\\Diamond\

  2. Partial differential equations

    CERN Document Server

    Agranovich, M S

    2002-01-01

    Mark Vishik's Partial Differential Equations seminar held at Moscow State University was one of the world's leading seminars in PDEs for over 40 years. This book celebrates Vishik's eightieth birthday. It comprises new results and survey papers written by many renowned specialists who actively participated over the years in Vishik's seminars. Contributions include original developments and methods in PDEs and related fields, such as mathematical physics, tomography, and symplectic geometry. Papers discuss linear and nonlinear equations, particularly linear elliptic problems in angles and gener

  3. Partial differential equations

    CERN Document Server

    Levine, Harold

    1997-01-01

    The subject matter, partial differential equations (PDEs), has a long history (dating from the 18th century) and an active contemporary phase. An early phase (with a separate focus on taut string vibrations and heat flow through solid bodies) stimulated developments of great importance for mathematical analysis, such as a wider concept of functions and integration and the existence of trigonometric or Fourier series representations. The direct relevance of PDEs to all manner of mathematical, physical and technical problems continues. This book presents a reasonably broad introductory account of the subject, with due regard for analytical detail, applications and historical matters.

  4. Partial differential equations

    CERN Document Server

    Sloan, D; Süli, E

    2001-01-01

    /homepage/sac/cam/na2000/index.html7-Volume Set now available at special set price ! Over the second half of the 20th century the subject area loosely referred to as numerical analysis of partial differential equations (PDEs) has undergone unprecedented development. At its practical end, the vigorous growth and steady diversification of the field were stimulated by the demand for accurate and reliable tools for computational modelling in physical sciences and engineering, and by the rapid development of computer hardware and architecture. At the more theoretical end, the analytical insight in

  5. Elliptic partial differential equations

    CERN Document Server

    Han, Qing

    2011-01-01

    Elliptic Partial Differential Equations by Qing Han and FangHua Lin is one of the best textbooks I know. It is the perfect introduction to PDE. In 150 pages or so it covers an amazing amount of wonderful and extraordinary useful material. I have used it as a textbook at both graduate and undergraduate levels which is possible since it only requires very little background material yet it covers an enormous amount of material. In my opinion it is a must read for all interested in analysis and geometry, and for all of my own PhD students it is indeed just that. I cannot say enough good things abo

  6. Generalized Partial Volume

    DEFF Research Database (Denmark)

    Darkner, Sune; Sporring, Jon

    2011-01-01

    Mutual Information (MI) and normalized mutual information (NMI) are popular choices as similarity measure for multimodal image registration. Presently, one of two approaches is often used for estimating these measures: The Parzen Window (PW) and the Generalized Partial Volume (GPV). Their theoret...... of view as well as w.r.t. computational complexity. Finally, we present algorithms for both approaches for NMI which is comparable in speed to Sum of Squared Differences (SSD), and we illustrate the differences between PW and GPV on a number of registration examples....

  7. Blind Naso-Endotracheal Intubation

    African Journals Online (AJOL)

    Difficult endotracheal intubation techniques include, use of fiberoptic bronchoscope, intubating laryngeal mask airway, tracheostomy, blind nasotracheal and retrograde intubation. According to the Difficult Airway Society guidelines, intubating with the aid of a fiberoptic scope has taken its place as the standard adjuvant for.

  8. Metro Navigation for the Blind

    Science.gov (United States)

    Sanchez, Jaime; Saenz, Mauricio

    2010-01-01

    This study evaluates the impact of using the software program AudioMetro, a tool that supports the orientation and mobility of people who are blind in the Metro system of Santiago de Chile. A quasi-experimental study considering experimental and control groups and using the paired Student's t in a two sample test analysis (pretest-posttest) was…

  9. Vesicouterine fistula and blind vagina

    International Nuclear Information System (INIS)

    Hafeez, M.; Hameed, S.; Asif, S.

    2003-01-01

    A case of vesicouterine fistula with blind vagina following cesarean section for obstructed labor is presented. It was surgically treated by fistulectomy, cervicoplasty and maintenance of bladder and cervical potency by catheterization. Intrauterine synechiae formation was prevented by copper T insertion and oral contraceptive pills. The patient is making uneventful a symptomatic progress planning to conceive. (author)

  10. Four different ways of philanthropic aid to the blind in medieval eastern Christendom.

    Science.gov (United States)

    Diamandopoulou-Drummond, A H; Diamandopoulos, A A; Marketos, S G

    1995-11-01

    The care of the blind, either as medical treatment or as divine therapy, has probably been the most ancient form of help for ill people. However, it was during the Byzantine Empire (325-1453 AD) that the state organized a 'blindness relief' plan as part of a widespread public health system. Our sources for the subject include medical writings, state decrees, Saint's 'vitae' and representations of relevant works of art. Based on the above data we classify the health care for the blind in Byzantium as: (a) support of ophthalmological education as evidenced by an abundance of medical writings on the subject; (b) establishment of charitable institutions exclusively or partially for the blind, where there was not only medical care but also provision for a wide range of social aid - the most advanced being specially trained escorts for each blind person; and (c) support by the state of an extended chain of religious institutions where miraculous help for the blind was promised. We conclude that the public health policy in Byzantium made adequate and very early provision for the blind.

  11. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... the special health problems and requirements of the blind.” News & Events Events Calendar NEI Press Releases News ... series. Dr. Sheldon Miller answers questions about color blindness, whether it can be treated, and how people ...

  12. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... series. Dr. Sheldon Miller answers questions about color blindness, whether it can be treated, and how people ... optical illusion? Click to Watch What is color blindness? Click to Watch How do I become a ...

  13. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... video series. Dr. Sheldon Miller answers questions about color blindness, whether it can be treated, and how people ... an optical illusion? Click to Watch What is color blindness? Click to Watch How do I become a ...

  14. Ask a Scientist: What is Color Blindness?

    Science.gov (United States)

    ... video series. Dr. Sheldon Miller answers questions about color blindness, whether it can be treated, and how people ... an optical illusion? Click to Watch What is color blindness? Click to Watch How do I become a ...

  15. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.” ... Clinical Studies Publications Catalog Photos ...

  16. Blinding in randomized clinical trials: imposed impartiality

    DEFF Research Database (Denmark)

    Hróbjartsson, A; Boutron, I

    2011-01-01

    Blinding, or "masking," is a crucial method for reducing bias in randomized clinical trials. In this paper, we review important methodological aspects of blinding, emphasizing terminology, reporting, bias mechanisms, empirical evidence, and the risk of unblinding. Theoretical considerations...

  17. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... Illusions Printables Ask a Scientist Video Series Why can’t you see colors well in the dark? ... Miller answers questions about color blindness, whether it can be treated, and how people become color blind. ...

  18. On imitation among young and blind children

    Directory of Open Access Journals (Sweden)

    Maria Rita Campello Rodrigues

    2016-07-01

    Full Text Available This article investigates the imitation among young and blind children. The survey was conducted as a mosaic in the time since the field considerations were taken from two areas: a professional experience with early stimulation of blind babies and a workshop with blind and low vision young between 13-18 years. By statingthe situated trace of knowledge, theresearch indicates that imitation among blind young people can be one of the ways of creating a common world among young blind and sighted people. Imitation among blind young is a multi-sensory process that requires a body experience, including both blind and people who see. The paper concludes with an indication of the unique character of imitation and at the same time, with the affirmation of its relevance to the development and inclusion process of both the child and the young blind.

  19. Unilateral removable partial dentures.

    Science.gov (United States)

    Goodall, W A; Greer, A C; Martin, N

    2017-01-27

    Removable partial dentures (RPDs) are widely used to replace missing teeth in order to restore both function and aesthetics for the partially dentate patient. Conventional RPD design is frequently bilateral and consists of a major connector that bridges both sides of the arch. Some patients cannot and will not tolerate such an extensive appliance. For these patients, bridgework may not be a predictable option and it is not always possible to provide implant-retained restorations. This article presents unilateral RPDs as a potential treatment modality for such patients and explores indications and contraindications for their use, including factors relating to patient history, clinical presentation and patient wishes. Through case examples, design, material and fabrication considerations will be discussed. While their use is not widespread, there are a number of patients who benefit from the provision of unilateral RPDs. They are a useful treatment to have in the clinician's armamentarium, but a highly-skilled dental team and a specific patient presentation is required in order for them to be a reasonable and predictable prosthetic option.

  20. "VisionTouch Phone" for the Blind.

    Science.gov (United States)

    Yong, Robest

    2013-10-01

    Our objective is to enable the blind to use smartphones with touchscreens to make calls and to send text messages (sms) with ease, speed, and accuracy. We believe that with our proposed platform, which enables the blind to locate the position of the keypads, new games and education, and safety applications will be increasingly developed for the blind. This innovative idea can also be implemented on tablets for the blind, allowing them to use information websites such as Wikipedia and newspaper portals.

  1. Tutorial on Online Partial Evaluation

    Directory of Open Access Journals (Sweden)

    William R. Cook

    2011-09-01

    Full Text Available This paper is a short tutorial introduction to online partial evaluation. We show how to write a simple online partial evaluator for a simple, pure, first-order, functional programming language. In particular, we show that the partial evaluator can be derived as a variation on a compositionally defined interpreter. We demonstrate the use of the resulting partial evaluator for program optimization in the context of model-driven development.

  2. What It's Like to Be Color Blind

    Science.gov (United States)

    ... a green leaf might look tan or gray. Color Blindness Is Passed Down Color blindness is almost always an inherited (say: in-HER- ... Eye doctors (and some school nurses) test for color blindness by showing a picture made up of different ...

  3. Occupant satisfaction with two blind control strategies

    DEFF Research Database (Denmark)

    Karlsen, Line Røseth; Heiselberg, Per Kvols; Bryn, Ida

    2015-01-01

    Highlights •Occupant satisfaction with two blind control strategies has been studied. •Control based on cut-off position of slats was more popular than closed slats. •Results from the study are helpful in development of control strategies for blinds. •The results give indications of how blinds...

  4. Type-Directed Partial Evaluation

    DEFF Research Database (Denmark)

    Danvy, Olivier

    1998-01-01

    Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML...

  5. Type-Directed Partial Evaluation

    DEFF Research Database (Denmark)

    Danvy, Olivier

    1998-01-01

    Type-directed partial evaluation uses a normalization function to achieve partial evaluation. These lecture notes review its background, foundations, practice, and applications. Of specific interest is the modular technique of offline and online type-directed partial evaluation in Standard ML of ...

  6. Bidirectional and Multi-User Telerehabilitation System: Clinical Effect on Balance, Functional Activity, and Satisfaction in Patients with Chronic Stroke Living in Long-Term Care Facilities

    Directory of Open Access Journals (Sweden)

    Kwan-Hwa Lin

    2014-07-01

    Full Text Available Background: The application of internet technology for telerehabilitation in patients with stroke has developed rapidly. Objective: The current study aimed to evaluate the effect of a bidirectional and multi-user telerehabilitation system on balance and satisfaction in patients with chronic stroke living in long-term care facilities (LTCFs. Method: This pilot study used a multi-site, blocked randomization design. Twenty-four participants from three LTCFs were recruited, and the participants were randomly assigned into the telerehabilitation (Tele and conventional therapy (Conv groups within each LTCF. Tele group received telerehabilitation but the Conv group received conventional therapy with two persons in each group for three sessions per week and for four weeks. The outcome measures included Berg Balance Scale (BBS, Barthel Index (BI, and the telerehabilitation satisfaction of the participants. Setting: A telerehabilitation system included “therapist end” in a laboratory, and the “client end” in LTCFs. The conventional therapy was conducted in LTCFs. Results: Training programs conducted for both the Tele and Conv groups showed significant effects within groups on the participant BBS as well as the total and self-care scores of BI. No significant difference between groups could be demonstrated. The satisfaction of participants between the Tele and the Conv groups also did not show significant difference. Conclusions: This pilot study indicated that the multi-user telerehabilitation program is feasible for improving the balance and functional activity similar to conventional therapy in patients with chronic stroke living in LTCFs.

  7. Investigation on iterative multiuser detection physical layer network coding in two-way relay free-space optical links with turbulences and pointing errors.

    Science.gov (United States)

    Abu-Almaalie, Zina; Ghassemlooy, Zabih; Bhatnagar, Manav R; Le-Minh, Hoa; Aslam, Nauman; Liaw, Shien-Kuei; Lee, It Ee

    2016-11-20

    Physical layer network coding (PNC) improves the throughput in wireless networks by enabling two nodes to exchange information using a minimum number of time slots. The PNC technique is proposed for two-way relay channel free space optical (TWR-FSO) communications with the aim of maximizing the utilization of network resources. The multipair TWR-FSO is considered in this paper, where a single antenna on each pair seeks to communicate via a common receiver aperture at the relay. Therefore, chip interleaving is adopted as a technique to separate the different transmitted signals at the relay node to perform PNC mapping. Accordingly, this scheme relies on the iterative multiuser technique for detection of users at the receiver. The bit error rate (BER) performance of the proposed system is examined under the combined influences of atmospheric loss, turbulence-induced channel fading, and pointing errors (PEs). By adopting the joint PNC mapping with interleaving and multiuser detection techniques, the BER results show that the proposed scheme can achieve a significant performance improvement against the degrading effects of turbulences and PEs. It is also demonstrated that a larger number of simultaneous users can be supported with this new scheme in establishing a communication link between multiple pairs of nodes in two time slots, thereby improving the channel capacity.

  8. Applied partial differential equations

    CERN Document Server

    Logan, J David

    2004-01-01

    This primer on elementary partial differential equations presents the standard material usually covered in a one-semester, undergraduate course on boundary value problems and PDEs. What makes this book unique is that it is a brief treatment, yet it covers all the major ideas: the wave equation, the diffusion equation, the Laplace equation, and the advection equation on bounded and unbounded domains. Methods include eigenfunction expansions, integral transforms, and characteristics. Mathematical ideas are motivated from physical problems, and the exposition is presented in a concise style accessible to science and engineering students; emphasis is on motivation, concepts, methods, and interpretation, rather than formal theory. This second edition contains new and additional exercises, and it includes a new chapter on the applications of PDEs to biology: age structured models, pattern formation; epidemic wave fronts, and advection-diffusion processes. The student who reads through this book and solves many of t...

  9. Inductance loop and partial

    CERN Document Server

    Paul, Clayton R

    2010-01-01

    "Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

  10. Fundamental partial compositeness

    CERN Document Server

    Sannino, Francesco

    2016-11-07

    We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Successful models exist because gauge quantum numbers of Standard Model fermions admit a minimal enough 'square root'. Furthermore, right-handed SM fermions have an SU(2)$_R$-like structure, yielding a custodially-protected composite Higgs. Baryon and lepton numbers arise accidentally. Standard Model fermions acquire mass at tree level, while the Higgs potential and flavor violations are generated by quantum corrections. We further discuss accidental symmetries and other dynamical features stemming from the new strongly interacting scalars. If the same phenomenology can be obtained from models without our elementary scalars, they would reappear as composite states.

  11. Fundamental partial compositeness

    International Nuclear Information System (INIS)

    Sannino, Francesco; Strumia, Alessandro; Tesi, Andrea; Vigiani, Elena

    2016-01-01

    We construct renormalizable Standard Model extensions, valid up to the Planck scale, that give a composite Higgs from a new fundamental strong force acting on fermions and scalars. Yukawa interactions of these particles with Standard Model fermions realize the partial compositeness scenario. Under certain assumptions on the dynamics of the scalars, successful models exist because gauge quantum numbers of Standard Model fermions admit a minimal enough ‘square root’. Furthermore, right-handed SM fermions have an SU(2)_R-like structure, yielding a custodially-protected composite Higgs. Baryon and lepton numbers arise accidentally. Standard Model fermions acquire mass at tree level, while the Higgs potential and flavor violations are generated by quantum corrections. We further discuss accidental symmetries and other dynamical features stemming from the new strongly interacting scalars. If the same phenomenology can be obtained from models without our elementary scalars, they would reappear as composite states.

  12. Partial oxidation process

    International Nuclear Information System (INIS)

    Najjar, M.S.

    1987-01-01

    A process is described for the production of gaseous mixtures comprising H/sub 2/+CO by the partial oxidation of a fuel feedstock comprising a heavy liquid hydrocarbonaceous fuel having a nickel, iron, and vanadium-containing ash or petroleum coke having a nickel, iron, and vanadium-containing ash, or mixtures thereof. The feedstock includes a minimum of 0.5 wt. % of sulfur and the ash includes a minimum of 5.0 wt. % vanadium, a minimum of 0.5 ppm nickel, and a minimum of 0.5 ppm iron. The process comprises: (1) mixing together a copper-containing additive with the fuel feedstock; wherein the weight ratio of copper-containing additive to ash in the fuel feedstock is in the range of about 1.0-10.0, and there is at least 10 parts by weight of copper for each part by weight of vanadium; (2) reacting the mixture from (1) at a temperature in the range of 2200 0 F to 2900 0 F and a pressure in the range of about 5 to 250 atmospheres in a free-flow refactory lined partial oxidation reaction zone with a free-oxygen containing gas in the presence of a temperature moderator and in a reducing atmosphere to produce a hot raw effluent gas stream comprising H/sub 2/+CO and entrained molten slag; and where in the reaction zone and the copper-containing additive combines with at least a portion of the nickel and iron constituents and sulfur found in the feedstock to produce a liquid phase washing agent that collects and transports at least a portion of the vanadium-containing oxide laths and spinels and other ash components and refractory out of the reaction zone; and (3) separating nongaseous materials from the hot raw effluent gas stream

  13. Rapid Assessment of Avoidable Blindness in Western Rwanda: Blindness in a Postconflict Setting

    OpenAIRE

    Mathenge, Wanjiku; Nkurikiye, John; Limburg, Hans; Kuper, Hannah

    2007-01-01

    Editors' Summary Background. VISION 2020, a global initiative that aims to eliminate avoidable blindness, has estimated that 75% of blindness worldwide is treatable or preventable. The WHO estimates that in Africa, around 9% of adults aged over 50 are blind. Some data suggest that people living in regions affected by violent conflict are more likely to be blind than those living in unaffected regions. Currently no data exist on the likely prevalence of blindness in Rwanda, a central African c...

  14. Contact Lenses for Color Blindness.

    Science.gov (United States)

    Badawy, Abdel-Rahman; Hassan, Muhammad Umair; Elsherif, Mohamed; Ahmed, Zubair; Yetisen, Ali K; Butt, Haider

    2018-06-01

    Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545-575 nm) to correct color vision blindness. The biocompatibility assessment of the dyed contact lenses in human corneal fibroblasts and human corneal epithelial cells shows no toxicity and cell viability remains at 99% after 72 h. This study demonstrates the potential of the dyed contact lenses in wavelength filtering and color vision deficiency management. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Demonstration of blind quantum computing.

    Science.gov (United States)

    Barz, Stefanie; Kashefi, Elham; Broadbent, Anne; Fitzsimons, Joseph F; Zeilinger, Anton; Walther, Philip

    2012-01-20

    Quantum computers, besides offering substantial computational speedups, are also expected to preserve the privacy of a computation. We present an experimental demonstration of blind quantum computing in which the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. Various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover quantum algorithms, are demonstrated. The client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.

  16. Blind Deconvolution With Model Discrepancies

    Czech Academy of Sciences Publication Activity Database

    Kotera, Jan; Šmídl, Václav; Šroubek, Filip

    2017-01-01

    Roč. 26, č. 5 (2017), s. 2533-2544 ISSN 1057-7149 R&D Projects: GA ČR GA13-29225S; GA ČR GA15-16928S Institutional support: RVO:67985556 Keywords : blind deconvolution * variational Bayes * automatic relevance determination Subject RIV: JD - Computer Applications, Robotics OBOR OECD: Computer hardware and architecture Impact factor: 4.828, year: 2016 http://library.utia.cas.cz/separaty/2017/ZOI/kotera-0474858.pdf

  17. Multichannel blind iterative image restoration

    Czech Academy of Sciences Publication Activity Database

    Šroubek, Filip; Flusser, Jan

    2003-01-01

    Roč. 12, č. 9 (2003), s. 1094-1106 ISSN 1057-7149 R&D Projects: GA ČR GA102/00/1711 Institutional research plan: CEZ:AV0Z1075907 Keywords : conjugate gradient * half-quadratic regularization * multichannel blind deconvolution Subject RIV: BD - Theory of Information Impact factor: 2.642, year: 2003 http://library.utia.cas.cz/prace/20030104.pdf

  18. Justifications shape ethical blind spots.

    Science.gov (United States)

    Pittarello, Andrea; Leib, Margarita; Gordon-Hecker, Tom; Shalvi, Shaul

    2015-06-01

    To some extent, unethical behavior results from people's limited attention to ethical considerations, which results in an ethical blind spot. Here, we focus on the role of ambiguity in shaping people's ethical blind spots, which in turn lead to their ethical failures. We suggest that in ambiguous settings, individuals' attention shifts toward tempting information, which determines the magnitude of their lies. Employing a novel ambiguous-dice paradigm, we asked participants to report the outcome of the die roll appearing closest to the location of a previously presented fixation cross on a computer screen; this outcome would determine their pay. We varied the value of the die second closest to the fixation cross to be either higher (i.e., tempting) or lower (i.e., not tempting) than the die closest to the fixation cross. Results of two experiments revealed that in ambiguous settings, people's incorrect responses were self-serving. Tracking participants' eye movements demonstrated that people's ethical blind spots are shaped by increased attention toward tempting information. © The Author(s) 2015.

  19. Adapting smart phone applications about physics education to blind students

    Science.gov (United States)

    Bülbül, M. Ş.; Yiğit, N.; Garip, B.

    2016-04-01

    Today, most of necessary equipment in a physics laboratory are available for smartphone users via applications. Physics teachers may measure from acceleration to sound volume with its internal sensors. These sensors collect data and smartphone applications make the raw data visible. Teachers who do not have well-equipped laboratories at their schools may have an opportunity to conduct experiments with the help of smart phones. In this study, we analyzed possible open source physics education applications in terms of blind users in inclusive learning environments. All apps are categorized as partially, full or non-supported. The roles of blind learner’s friend during the application are categorized as reader, describer or user. Mentioned apps in the study are compared with additional opportunities like size and downloading rates. Out of using apps we may also get information about whether via internet and some other extra information for different experiments in physics lab. Q-codes reading or augmented reality are two other opportunity provided by smart phones for users in physics labs. We also summarized blind learner’s smartphone experiences from literature and listed some suggestions for application designers about concepts in physics.

  20. Experts' understanding of partial derivatives using the Partial Derivative Machine

    OpenAIRE

    Roundy, David; Dorko, Allison; Dray, Tevian; Manogue, Corinne A.; Weber, Eric

    2014-01-01

    Partial derivatives are used in a variety of different ways within physics. Most notably, thermodynamics uses partial derivatives in ways that students often find confusing. As part of a collaboration with mathematics faculty, we are at the beginning of a study of the teaching of partial derivatives, a goal of better aligning the teaching of multivariable calculus with the needs of students in STEM disciplines. As a part of this project, we have performed a pilot study of expert understanding...

  1. Partial Actions and Power Sets

    Directory of Open Access Journals (Sweden)

    Jesús Ávila

    2013-01-01

    Full Text Available We consider a partial action (X,α with enveloping action (T,β. In this work we extend α to a partial action on the ring (P(X,Δ,∩ and find its enveloping action (E,β. Finally, we introduce the concept of partial action of finite type to investigate the relationship between (E,β and (P(T,β.

  2. Algorithms over partially ordered sets

    DEFF Research Database (Denmark)

    Baer, Robert M.; Østerby, Ole

    1969-01-01

    in partially ordered sets, answer the combinatorial question of how many maximal chains might exist in a partially ordered set withn elements, and we give an algorithm for enumerating all maximal chains. We give (in § 3) algorithms which decide whether a partially ordered set is a (lower or upper) semi......-lattice, and whether a lattice has distributive, modular, and Boolean properties. Finally (in § 4) we give Algol realizations of the various algorithms....

  3. Better outcome from arthroscopic partial meniscectomy than skin incisions only?

    DEFF Research Database (Denmark)

    Roos, Ewa M; Hare, Kristoffer Borbjerg; Nielsen, Sabrina Mai

    2018-01-01

    . In total, nine participants experienced 11 adverse events; six in the surgery group and three in the skin-incisions-only group. CONCLUSION: We found greater improvement from arthroscopic partial meniscectomy compared with skin incisions only at 2 years, with the statistical uncertainty of the between......-group difference including what could be considered clinically relevant. Because of the study being underpowered, nearly half in the sham group being non-blinded and one-third crossing over to surgery, the results cannot be generalised to the greater patient population. TRIAL REGISTRATION NUMBER: NCT01264991....

  4. Blindness

    Science.gov (United States)

    ... NEI Intranet (Employees Only) *PDF files require the free Adobe® Reader® software for viewing. This website is maintained by the NEI Office of Science Communications, Public Liaison, and Education. Technical questions about this website can be addressed ...

  5. Anatomic partial nephrectomy: technique evolution.

    Science.gov (United States)

    Azhar, Raed A; Metcalfe, Charles; Gill, Inderbir S

    2015-03-01

    Partial nephrectomy provides equivalent long-term oncologic and superior functional outcomes as radical nephrectomy for T1a renal masses. Herein, we review the various vascular clamping techniques employed during minimally invasive partial nephrectomy, describe the evolution of our partial nephrectomy technique and provide an update on contemporary thinking about the impact of ischemia on renal function. Recently, partial nephrectomy surgical technique has shifted away from main artery clamping and towards minimizing/eliminating global renal ischemia during partial nephrectomy. Supported by high-fidelity three-dimensional imaging, novel anatomic-based partial nephrectomy techniques have recently been developed, wherein partial nephrectomy can now be performed with segmental, minimal or zero global ischemia to the renal remnant. Sequential innovations have included early unclamping, segmental clamping, super-selective clamping and now culminating in anatomic zero-ischemia surgery. By eliminating 'under-the-gun' time pressure of ischemia for the surgeon, these techniques allow an unhurried, tightly contoured tumour excision with point-specific sutured haemostasis. Recent data indicate that zero-ischemia partial nephrectomy may provide better functional outcomes by minimizing/eliminating global ischemia and preserving greater vascularized kidney volume. Contemporary partial nephrectomy includes a spectrum of surgical techniques ranging from conventional-clamped to novel zero-ischemia approaches. Technique selection should be tailored to each individual case on the basis of tumour characteristics, surgical feasibility, surgeon experience, patient demographics and baseline renal function.

  6. Partial order infinitary term rewriting

    DEFF Research Database (Denmark)

    Bahr, Patrick

    2014-01-01

    We study an alternative model of infinitary term rewriting. Instead of a metric on terms, a partial order on partial terms is employed to formalise convergence of reductions. We consider both a weak and a strong notion of convergence and show that the metric model of convergence coincides with th...... to the metric setting -- orthogonal systems are both infinitarily confluent and infinitarily normalising in the partial order setting. The unique infinitary normal forms that the partial order model admits are Böhm trees....

  7. Sensory augmentation for the blind

    Directory of Open Access Journals (Sweden)

    Silke Manuela Kärcher

    2012-03-01

    Full Text Available Enacted theories of consciousness conjecture that perception and cognition arise from an active experience of the regular relations that are tying together the sensory stimulation of different modalities and associated motor actions. Previous experiments investigated this concept by employing the technique of sensory substitution. Building on these studies, here we test a set of hypotheses derived from this framework and investigate the utility of sensory augmentation in handicapped people. We provide a late blind subject with a new set of sensorimotor laws: A vibro-tactile belt continually signals the direction of magnetic north. The subject completed a set of behavioral tests before and after an extended training period. The tests were complemented by questionnaires and interviews. This newly supplied information improved performance on different time scales. In a pointing task we demonstrate an instant improvement of performance based on the signal provided by the device. Furthermore, the signal was helpful in relevant daily tasks, often complicated for the blind, such as keeping a direction over longer distances or taking shortcuts in familiar environments. A homing task with an additional attentional load demonstrated a significant improvement after training. The subject found the directional information highly expedient for the adjustment of his inner maps of familiar environments and describes an increase in his feeling of security when exploring unfamiliar environments with the belt. The results give evidence for a firm integration of the newly supplied signals into the behavior of this late blind subject with better navigational performance and more courageous behavior in unfamiliar environments. Most importantly, the complementary information provided by the belt lead to a positive emotional impact with enhanced feeling of security. This experimental approach demonstrates the potential of sensory augmentation devices for the help of

  8. Change blindness, aging, and cognition.

    Science.gov (United States)

    Rizzo, Matthew; Sparks, Jondavid; McEvoy, Sean; Viamonte, Sarah; Kellison, Ida; Vecera, Shaun P

    2009-02-01

    Change blindness (CB), the inability to detect changes in visual scenes, may increase with age and early Alzheimer's disease (AD). To test this hypothesis, participants were asked to localize changes in natural scenes. Dependent measures were response time (RT), hit rate, false positives (FP), and true sensitivity (d'). Increased age correlated with increased sensitivity and RT; AD predicted even slower RT. Accuracy and RT were negatively correlated. Differences in FP were nonsignificant. CB correlated with impaired attention, working memory, and executive function. Advanced age and AD were associated with increased CB, perhaps due to declining memory and attention. CB could affect real-world tasks, like automobile driving.

  9. Surveillance-based Mechanisms in MUVEs (MultiUser Virtual Environments used for Monitoring, Data Gathering and Evaluation of Knowledge Transfer in VirtuReality

    Directory of Open Access Journals (Sweden)

    Jakub Štogr

    2011-04-01

    Full Text Available Multiuser virtual environments (MUVEs generate a large amount of data but most of them are not accessible even to users who triggered them. What’s more, most datasets are not even stored for further use; they have only temporary character and very short "halftime of decay" limited f.e. to onesecondlong screen display. Such a huge loss of data makes evaluation of knowledge transfer in MUVEs almost impossible. There is a need to both improve monitoring capabilities of MUVEs to be able to make completion assessment and use MUVEs that enable simulation (reexperience using complete datasets gathered from environment itself. Future research in the field of simulation methodology is suggested.

  10. An Improved Digital Signature Protocol to Multi-User Broadcast Authentication Based on Elliptic Curve Cryptography in Wireless Sensor Networks (WSNs

    Directory of Open Access Journals (Sweden)

    Hamed Bashirpour

    2018-03-01

    Full Text Available In wireless sensor networks (WSNs, users can use broadcast authentication mechanisms to connect to the target network and disseminate their messages within the network. Since data transfer for sensor networks is wireless, as a result, attackers can easily eavesdrop deployed sensor nodes and the data sent between them or modify the content of eavesdropped data and inject false data into the sensor network. Hence, the implementation of the message authentication mechanisms (in order to avoid changes and injecting messages into the network of wireless sensor networks is essential. In this paper, we present an improved protocol based on elliptic curve cryptography (ECC to accelerate authentication of multi-user message broadcasting. In comparison with previous ECC-based schemes, complexity and computational overhead of proposed scheme is significantly decreased. Also, the proposed scheme supports user anonymity, which is an important property in broadcast authentication schemes for WSNs to preserve user privacy and user untracking.

  11. Blind Signal Classification via Spare Coding

    Science.gov (United States)

    2016-04-10

    Blind Signal Classification via Sparse Coding Youngjune Gwon MIT Lincoln Laboratory gyj@ll.mit.edu Siamak Dastangoo MIT Lincoln Laboratory sia...achieve blind signal classification with no prior knowledge about signals (e.g., MCS, pulse shaping) in an arbitrary RF channel. Since modulated RF...classification method. Our results indicate that we can separate different classes of digitally modulated signals from blind sampling with 70.3% recall and 24.6

  12. Tactile maze solving in congenitally blind individuals

    DEFF Research Database (Denmark)

    Gagnon, Léa; Kupers, Ron; Schneider, Fabien C

    2010-01-01

    and environmental cues such as temperature and echolocation. We hypothesize that by limiting these cues, blind individuals will lose their advantage compared with controls in spatial navigation tasks. We therefore evaluated the performance of blind and sighted individuals in small-scale, tactile multiple T mazes....... Our results show that blindfolded sighted controls outperformed blind participants in the route-learning tasks. This suggests that, contrary to indoor large-scale spaces, navigational skills inside small-scale spaces benefit from visual experience....

  13. Finding Objects for Assisting Blind People

    OpenAIRE

    Yi, Chucai; Flores, Roberto W.; Chincha, Ricardo; Tian, YingLi

    2013-01-01

    Computer vision technology has been widely used for blind assistance, such as navigation and wayfinding. However, few camera-based systems are developed for helping blind or visually-impaired people to find daily necessities. In this paper, we propose a prototype system of blind-assistant object finding by camera-based network and matching-based recognition. We collect a dataset of daily necessities and apply Speeded-Up Robust Features (SURF) and Scale Invariant Feature Transform (SIFT) featu...

  14. On Degenerate Partial Differential Equations

    OpenAIRE

    Chen, Gui-Qiang G.

    2010-01-01

    Some of recent developments, including recent results, ideas, techniques, and approaches, in the study of degenerate partial differential equations are surveyed and analyzed. Several examples of nonlinear degenerate, even mixed, partial differential equations, are presented, which arise naturally in some longstanding, fundamental problems in fluid mechanics and differential geometry. The solution to these fundamental problems greatly requires a deep understanding of nonlinear degenerate parti...

  15. [Acrylic resin removable partial dentures

    NARCIS (Netherlands)

    Baat, C. de; Witter, D.J.; Creugers, N.H.J.

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of

  16. Partial Epilepsy with Auditory Features

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-07-01

    Full Text Available The clinical characteristics of 53 sporadic (S cases of idiopathic partial epilepsy with auditory features (IPEAF were analyzed and compared to previously reported familial (F cases of autosomal dominant partial epilepsy with auditory features (ADPEAF in a study at the University of Bologna, Italy.

  17. Tactile spatial resolution in blind braille readers.

    Science.gov (United States)

    Van Boven, R W; Hamilton, R H; Kauffman, T; Keenan, J P; Pascual-Leone, A

    2000-06-27

    To determine if blind people have heightened tactile spatial acuity. Recently, studies using magnetic source imaging and somatosensory evoked potentials have shown that the cortical representation of the reading fingers of blind Braille readers is expanded compared to that of fingers of sighted subjects. Furthermore, the visual cortex is activated during certain tactile tasks in blind subjects but not sighted subjects. The authors hypothesized that the expanded cortical representation of fingers used in Braille reading may reflect an enhanced fidelity in the neural transmission of spatial details of a stimulus. If so, the quantitative limit of spatial acuity would be superior in blind people. The authors employed a grating orientation discrimination task in which threshold performance is accounted for by the spatial resolution limits of the neural image evoked by a stimulus. The authors quantified the psychophysical limits of spatial acuity at the middle and index fingers of 15 blind Braille readers and 15 sighted control subjects. The mean grating orientation threshold was significantly (p = 0.03) lower in the blind group (1.04 mm) compared to the sighted group (1.46 mm). The self-reported dominant reading finger in blind subjects had a mean grating orientation threshold of 0.80 mm, which was significantly better than other fingers tested. Thresholds at non-Braille reading fingers in blind subjects averaged 1.12 mm, which were also superior to sighted subjects' performances. Superior tactile spatial acuity in blind Braille readers may represent an adaptive, behavioral correlate of cortical plasticity.

  18. Blind Grid Scoring Record No. 290

    National Research Council Canada - National Science Library

    Overbay, Larry; Robitaille, George

    2005-01-01

    ...) utilizing the APG Standardized UXO Technology Demonstration Site Blind Grid. Scoring Records have been coordinated by Larry Overbay and the Standardized UXO Technology Demonstration Site Scoring Committee...

  19. Blind Grid Scoring Record No. 293

    National Research Council Canada - National Science Library

    Overbay, Larry; Robitaille, George; Archiable, Robert; Fling, Rick; McClung, Christina

    2005-01-01

    ...) utilizing the YPG Standardized UXO Technology Demonstration Site Blind Grid. Scoring Records have been coordinated by Larry Overbay and the Standardized UXO Technology Demonstration Site Scoring Committee...

  20. Congenital color blindness in young Turkish men.

    Science.gov (United States)

    Citirik, Mehmet; Acaroglu, Golge; Batman, Cosar; Zilelioglu, Orhan

    2005-04-01

    We investigated a healthy population of men from different regions of Turkey for the presence of congenital red-green color blindness. Using Ishihara pseudoisochromatic plates, 941 healthy men from the Turkish army were tested for congenital red-green color blindness. The prevalence of red-green color blindness was 7.33 +/- 0.98% (5.10% protans and 2.23% deutans). These ratios were higher than other reported samples from Mediterranean Europe. Higher percentages of color blindness were found in regions with a lower education level and more consanguineous marriages.

  1. Blindness and Insight in King Lear

    Institute of Scientific and Technical Information of China (English)

    岳元玉

    2008-01-01

    This paper intends to explore how William Shakespeare illustrates the theme of blindness and insight in his great tragedy "King Lear".Four characters’ deeds and their fate are used as a case study to examine what blindness is,what insight is,and the relationship between the two.The writer finds that by depicting the characters’ deeds and their fate in a double plot,Shakespeare renders the folly of blindness,the transition from blindness to insight,and the use of reason and thought to understand the truth.

  2. Causes of blindness and career choice among pupils in a blind ...

    African Journals Online (AJOL)

    available eye care services Furthermore there is need for career talk in schools for the blind to ... career where their potential can be fully maximized. .... tropicamide 1% eye drops. .... Foster A, Gilbert C. Epidemiology of childhood blindness.

  3. Partial twisting for scalar mesons

    International Nuclear Information System (INIS)

    Agadjanov, Dimitri; Meißner, Ulf-G.; Rusetsky, Akaki

    2014-01-01

    The possibility of imposing partially twisted boundary conditions is investigated for the scalar sector of lattice QCD. According to the commonly shared belief, the presence of quark-antiquark annihilation diagrams in the intermediate state generally hinders the use of the partial twisting. Using effective field theory techniques in a finite volume, and studying the scalar sector of QCD with total isospin I=1, we however demonstrate that partial twisting can still be performed, despite the fact that annihilation diagrams are present. The reason for this are delicate cancellations, which emerge due to the graded symmetry in partially quenched QCD with valence, sea and ghost quarks. The modified Lüscher equation in case of partial twisting is given

  4. Definition of blindness under National Programme for Control of Blindness: Do we need to revise it?

    Science.gov (United States)

    Vashist, Praveen; Senjam, Suraj Singh; Gupta, Vivek; Gupta, Noopur; Kumar, Atul

    2017-02-01

    A review appropriateness of the current definition of blindness under National Programme for Control of Blindness (NPCB), Government of India. Online search of peer-reviewed scientific published literature and guidelines using PubMed, the World Health Organization (WHO) IRIS, and Google Scholar with keywords, namely blindness and visual impairment, along with offline examination of reports of national and international organizations, as well as their cross-references was done until December 2016, to identify relevant documents on the definition of blindness. The evidence for the historical and currently adopted definition of blindness under the NPCB, the WHO, and other countries was reviewed. Differences in the NPCB and WHO definitions were analyzed to assess the impact on the epidemiological status of blindness and visual impairment in India. The differences in the criteria for blindness under the NPCB and the WHO definitions cause an overestimation of the prevalence of blindness in India. These variations are also associated with an over-representation of refractive errors as a cause of blindness and an under-representation of other causes under the NPCB definition. The targets for achieving elimination of blindness also become much more difficult to achieve under the NPCB definition. Ignoring differences in definitions when comparing the global and Indian prevalence of blindness will cause erroneous interpretations. We recommend that the appropriate modifications should be made in the NPCB definition of blindness to make it consistent with the WHO definition.

  5. Childhood Fears among Children Who Are Blind: The Perspective of Teachers Who Are Blind

    Science.gov (United States)

    Al-Zboon, Eman

    2017-01-01

    The aim of this study was to investigate childhood fears in children who are blind from the perspective of teachers who are blind. The study was conducted in Jordan. Forty-six teachers were interviewed. Results revealed that the main fear content in children who are blind includes fear of the unknown; environment-, transportation- and…

  6. Definition of blindness under National Programme for Control of Blindness: Do we need to revise it?

    Directory of Open Access Journals (Sweden)

    Praveen Vashist

    2017-01-01

    Full Text Available A review appropriateness of the current definition of blindness under National Programme for Control of Blindness (NPCB, Government of India. Online search of peer-reviewed scientific published literature and guidelines using PubMed, the World Health Organization (WHO IRIS, and Google Scholar with keywords, namely blindness and visual impairment, along with offline examination of reports of national and international organizations, as well as their cross-references was done until December 2016, to identify relevant documents on the definition of blindness. The evidence for the historical and currently adopted definition of blindness under the NPCB, the WHO, and other countries was reviewed. Differences in the NPCB and WHO definitions were analyzed to assess the impact on the epidemiological status of blindness and visual impairment in India. The differences in the criteria for blindness under the NPCB and the WHO definitions cause an overestimation of the prevalence of blindness in India. These variations are also associated with an over-representation of refractive errors as a cause of blindness and an under-representation of other causes under the NPCB definition. The targets for achieving elimination of blindness also become much more difficult to achieve under the NPCB definition. Ignoring differences in definitions when comparing the global and Indian prevalence of blindness will cause erroneous interpretations. We recommend that the appropriate modifications should be made in the NPCB definition of blindness to make it consistent with the WHO definition.

  7. 42 CFR 436.531 - Determination of blindness.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Determination of blindness. 436.531 Section 436.531... Requirements for Medicaid Eligibility Blindness § 436.531 Determination of blindness. In determining blindness... determine on behalf of the agency— (1) Whether the individual meets the definition of blindness; and (2...

  8. Cast Partial Denture versus Acrylic Partial Denture for Replacement of Missing Teeth in Partially Edentulous Patients

    Directory of Open Access Journals (Sweden)

    Pramita Suwal

    2017-03-01

    Full Text Available Aim: To compare the effects of cast partial denture with conventional all acrylic denture in respect to retention, stability, masticatory efficiency, comfort and periodontal health of abutments. Methods: 50 adult partially edentulous patient seeking for replacement of missing teeth having Kennedy class I and II arches with or without modification areas were selected for the study. Group-A was treated with cast partial denture and Group-B with acrylic partial denture. Data collected during follow-up visit of 3 months, 6 months, and 1 year by evaluating retention, stability, masticatory efficiency, comfort, periodontal health of abutment. Results: Chi-square test was applied to find out differences between the groups at 95% confidence interval where p = 0.05. One year comparison shows that cast partial denture maintained retention and stability better than acrylic partial denture (p< 0.05. The masticatory efficiency was significantly compromising from 3rd month to 1 year in all acrylic partial denture groups (p< 0.05. The comfort of patient with cast partial denture was maintained better during the observation period (p< 0.05. Periodontal health of abutment was gradually deteriorated in all acrylic denture group (p

  9. Can a Blind Person Play Dodge Ball? Enacting Body and Cognition with a Group of Youths with Visual Disabilities

    Science.gov (United States)

    Moraes, Marcia

    2012-01-01

    This paper presents some results of research carried out with a group of blind and partially sighted youths who are enrolled in a school for people with visual disabilities in Brazil. This research aims to promote different articulations between the body and cognition. Based on actor-network theory, it considers that having a body means learning…

  10. Semi-Blind Noise Extraction Using Partially Known Position of the Target Source

    Czech Academy of Sciences Publication Activity Database

    Koldovský, Zbyněk; Málek, J.; Tichavský, Petr; Nesta, F.

    2013-01-01

    Roč. 21, č. 10 (2013), s. 2029-2041 ISSN 1558-7916 Grant - others:GA ČR(CZ) GAP103/11/1947 Program:GA Institutional support: RVO:67985556 Keywords : Independent component analysis * noise extraction * generalized sidelobe canceler Subject RIV: BI - Acoustics Impact factor: 2.625, year: 2013 http://library.utia.cas.cz/separaty/2013/SI/tichavsky-0396861.pdf

  11. 33 CFR 117.861 - Blind Slough.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Blind Slough. 117.861 Section 117.861 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES DRAWBRIDGE OPERATION REGULATIONS Specific Requirements Oregon § 117.861 Blind Slough. The draws of the Portland and...

  12. Mentoring Transition-Age Youth with Blindness

    Science.gov (United States)

    Bell, Edward C.

    2012-01-01

    This article reports on a mentoring project designed for transition-age youth (ages 16-26) who are persons with legal blindness. Youth were matched with adult mentors who were also persons with blindness but who have achieved academic and career success. Results demonstrate that youth who participated in the project for 2 years had significant…

  13. Blindness and visual impairment in opera.

    Science.gov (United States)

    Aydin, Pinar; Ritch, Robert; O'Dwyer, John

    2018-01-01

    The performing arts mirror the human condition. This study sought to analyze the reasons for inclusion of visually impaired characters in opera, the cause of the blindness or near blindness, and the dramatic purpose of the blindness in the storyline. We reviewed operas from the 18 th century to 2010 and included all characters with ocular problems. We classified the cause of each character's ocular problem (organic, nonorganic, and other) in relation to the thematic setting of the opera: biblical and mythical, blind beggars or blind musicians, historical (real or fictional characters), and contemporary or futuristic. Cases of blindness in 55 characters (2 as a choir) from 38 operas were detected over 3 centuries of repertoire: 11 had trauma-related visual impairment, 5 had congenital blindness, 18 had visual impairment of unknown cause, 9 had psychogenic or malingering blindness, and 12 were symbolic or miracle-related. One opera featured an ophthalmologist curing a patient. The research illustrates that visual impairment was frequently used as an artistic device to enhance the intent and situate an opera in its time.

  14. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... blindness, whether it can be treated, and how people become color blind. What do my eyes do when I’m sleeping? Click to Watch What does it mean to be nearsighted or farsighted? Click to Watch Do fish have eyelids? Click to Watch Why don’t all animal eyes look the same? Click to Watch Why ...

  15. A Taxonomy for Mannerisms of Blind Children.

    Science.gov (United States)

    Eichel, Valerie J.

    1979-01-01

    The investigation involving 24 blind children (2-11 years old) set out to develop and validate a coding procedure which employed a set of 34 descriptors with their corresponding definitions. The use of the taxonomy enabled a detailed, systematic study of manneristic behavior in blind children. (Author/SBH)

  16. 45 CFR 233.70 - Blindness.

    Science.gov (United States)

    2010-10-01

    ...). Such physician is responsible for making the agency's decision that the applicant or recipient does or... XVI of the Social Security Act must: (1) Contain a definition of blindness in terms of ophthalmic measurement. The following definition is recommended: An individual is considered blind if he has central...

  17. Tackling the high burden of blindness

    African Journals Online (AJOL)

    ... care delivery, and tackling the five major eye conditions that contribute to most blindness could reduce the current burden of blindness. This would open the window for addressing glaucoma, diabetic retinopathy, and macula degeneration which are the new emerging global consequences of non-communicable diseases.

  18. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, and the special health problems and requirements of the blind.” ... DeMott, Media Relations Kathryn.DeMott@nih.gov NEI Office of Communications ( ...

  19. Individual Differences in Susceptibility to Inattentional Blindness

    Science.gov (United States)

    Seegmiller, Janelle K.; Watson, Jason M.; Strayer, David L.

    2011-01-01

    Inattentional blindness refers to the finding that people do not always see what appears in their gaze. Though inattentional blindness affects large percentages of people, it is unclear if there are individual differences in susceptibility. The present study addressed whether individual differences in attentional control, as reflected by…

  20. Deaf-Blind Perspectives, 2000-2001.

    Science.gov (United States)

    Malloy, Peggy, Ed.

    2001-01-01

    These three issues of "Deaf-Blind Perspectives" feature the following articles: (1) "A Group for Students with Usher Syndrome in South Louisiana" (Faye Melancon); (2) "Simply Emily," which discusses a budding friendship between a girl with deaf-blindness and a peer; (3) "Intervener Update" (Peggy Malloy and…

  1. Blindness in designing intelligent systems

    Science.gov (United States)

    Denning, Peter J.

    1988-01-01

    New investigations of the foundations of artificial intelligence are challenging the hypothesis that problem solving is the cornerstone of intelligence. New distinctions among three domains of concern for humans--description, action, and commitment--have revealed that the design process for programmable machines, such as expert systems, is based on descriptions of actions and induces blindness to nonanalytic action and commitment. Design processes focusing in the domain of description are likely to yield programs like burearcracies: rigid, obtuse, impersonal, and unable to adapt to changing circumstances. Systems that learn from their past actions, and systems that organize information for interpretation by human experts, are more likely to be successful in areas where expert systems have failed.

  2. Blind-date Conversation Joining

    Directory of Open Access Journals (Sweden)

    Luca Cesari

    2013-07-01

    Full Text Available We focus on a form of joining conversations among multiple parties in service-oriented applications where a client may asynchronously join an existing conversation without need to know in advance any information about it. More specifically, we show how the correlation mechanism provided by orchestration languages enables a form of conversation joining that is completely transparent to clients and that we call 'blind-date joining'. We provide an implementation of this strategy by using the standard orchestration language WS-BPEL. We then present its formal semantics by resorting to COWS, a process calculus specifically designed for modelling service-oriented applications. We illustrate our approach by means of a simple, but realistic, case study from the online games domain.

  3. Convolutive Blind Source Separation Methods

    DEFF Research Database (Denmark)

    Pedersen, Michael Syskind; Larsen, Jan; Kjems, Ulrik

    2008-01-01

    During the past decades, much attention has been given to the separation of mixed sources, in particular for the blind case where both the sources and the mixing process are unknown and only recordings of the mixtures are available. In several situations it is desirable to recover all sources from...... the recorded mixtures, or at least to segregate a particular source. Furthermore, it may be useful to identify the mixing process itself to reveal information about the physical mixing system. In some simple mixing models each recording consists of a sum of differently weighted source signals. However, in many...... real-world applications, such as in acoustics, the mixing process is more complex. In such systems, the mixtures are weighted and delayed, and each source contributes to the sum with multiple delays corresponding to the multiple paths by which an acoustic signal propagates to a microphone...

  4. Unconditionally verifiable blind quantum computation

    Science.gov (United States)

    Fitzsimons, Joseph F.; Kashefi, Elham

    2017-07-01

    Blind quantum computing (BQC) allows a client to have a server carry out a quantum computation for them such that the client's input, output, and computation remain private. A desirable property for any BQC protocol is verification, whereby the client can verify with high probability whether the server has followed the instructions of the protocol or if there has been some deviation resulting in a corrupted output state. A verifiable BQC protocol can be viewed as an interactive proof system leading to consequences for complexity theory. We previously proposed [A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual Symposium on Foundations of Computer Science, Atlanta, 2009 (IEEE, Piscataway, 2009), p. 517] a universal and unconditionally secure BQC scheme where the client only needs to be able to prepare single qubits in separable states randomly chosen from a finite set and send them to the server, who has the balance of the required quantum computational resources. In this paper we extend that protocol with additional functionality allowing blind computational basis measurements, which we use to construct another verifiable BQC protocol based on a different class of resource states. We rigorously prove that the probability of failing to detect an incorrect output is exponentially small in a security parameter, while resource overhead remains polynomial in this parameter. This resource state allows entangling gates to be performed between arbitrary pairs of logical qubits with only constant overhead. This is a significant improvement on the original scheme, which required that all computations to be performed must first be put into a nearest-neighbor form, incurring linear overhead in the number of qubits. Such an improvement has important consequences for efficiency and fault-tolerance thresholds.

  5. Blind Braille readers mislocate tactile stimuli.

    Science.gov (United States)

    Sterr, Annette; Green, Lisa; Elbert, Thomas

    2003-05-01

    In a previous experiment, we observed that blind Braille readers produce errors when asked to identify on which finger of one hand a light tactile stimulus had occurred. With the present study, we aimed to specify the characteristics of this perceptual error in blind and sighted participants. The experiment confirmed that blind Braille readers mislocalised tactile stimuli more often than sighted controls, and that the localisation errors occurred significantly more often at the right reading hand than at the non-reading hand. Most importantly, we discovered that the reading fingers showed the smallest error frequency, but the highest rate of stimulus attribution. The dissociation of perceiving and locating tactile stimuli in the blind suggests altered tactile information processing. Neuroplasticity, changes in tactile attention mechanisms as well as the idea that blind persons may employ different strategies for tactile exploration and object localisation are discussed as possible explanations for the results obtained.

  6. Subcortical functional reorganization due to early blindness.

    Science.gov (United States)

    Coullon, Gaelle S L; Jiang, Fang; Fine, Ione; Watkins, Kate E; Bridge, Holly

    2015-04-01

    Lack of visual input early in life results in occipital cortical responses to auditory and tactile stimuli. However, it remains unclear whether cross-modal plasticity also occurs in subcortical pathways. With the use of functional magnetic resonance imaging, auditory responses were compared across individuals with congenital anophthalmia (absence of eyes), those with early onset (in the first few years of life) blindness, and normally sighted individuals. We find that the superior colliculus, a "visual" subcortical structure, is recruited by the auditory system in congenital and early onset blindness. Additionally, auditory subcortical responses to monaural stimuli were altered as a result of blindness. Specifically, responses in the auditory thalamus were equally strong to contralateral and ipsilateral stimulation in both groups of blind subjects, whereas sighted controls showed stronger responses to contralateral stimulation. These findings suggest that early blindness results in substantial reorganization of subcortical auditory responses. Copyright © 2015 the American Physiological Society.

  7. Preserved sleep microstructure in blind individuals

    DEFF Research Database (Denmark)

    Aubin, Sébrina; Christensen, Julie A.E.; Jennum, Poul

    2018-01-01

    , as light is the primary zeitgeber of the master biological clock found in the suprachiasmatic nucleus of the hypothalamus. In addition, a greater number of sleep disturbances is often reported in blind individuals. Here, we examined various electroencephalographic microstructural components of sleep, both...... during rapid-eye-movement (REM) sleep and non-REM (NREM) sleep, between blind individuals, including both of early and late onset, and normal-sighted controls. During wakefulness, occipital alpha oscillations were lower, or absent in blind individuals. During sleep, differences were observed across...... electrode derivations between the early and late blind samples, which may reflect altered cortical networking in early blindness. Despite these differences in power spectra density, the electroencephalography microstructure of sleep, including sleep spindles, slow wave activity, and sawtooth waves, remained...

  8. In blind pursuit of racial equality?

    Science.gov (United States)

    Apfelbaum, Evan P; Pauker, Kristin; Sommers, Samuel R; Ambady, Nalini

    2010-11-01

    Despite receiving little empirical assessment, the color-blind approach to managing diversity has become a leading institutional strategy for promoting racial equality, across domains and scales of practice. We gauged the utility of color blindness as a means to eliminating future racial inequity--its central objective--by assessing its impact on a sample of elementary-school students. Results demonstrated that students exposed to a color-blind mind-set, as opposed to a value-diversity mind-set, were actually less likely both to detect overt instances of racial discrimination and to describe such events in a manner that would prompt intervention by certified teachers. Institutional messages of color blindness may therefore artificially depress formal reporting of racial injustice. Color-blind messages may thus appear to function effectively on the surface even as they allow explicit forms of bias to persist.

  9. User-centered Technologies For Blind Children

    Directory of Open Access Journals (Sweden)

    Jaime Sánchez

    2008-01-01

    Full Text Available The purpose of this paper is to review, summarize, and illustrate research work involving four audio-based games created within a user-centered design methodology through successive usability tasks and evaluations. These games were designed by considering the mental model of blind children and their styles of interaction to perceive and process data and information. The goal of these games was to enhance the cognitive development of spatial structures, memory, haptic perception, mathematical skills, navigation and orientation, and problem solving of blind children. Findings indicate significant improvements in learning and cognition from using audio-based tools specially tailored for the blind. That is, technologies for blind children, carefully tailored through user-centered design approaches, can make a significant contribution to cognitive development of these children. This paper contributes new insight into the design and implementation of audio-based virtual environments to facilitate learning and cognition in blind children.

  10. An Adaptive Fuzzy-Based System to Simulate, Quantify and Compensate Color Blindness

    OpenAIRE

    Lee, Jinmi; Santos, Wellington Pinheiro dos

    2017-01-01

    About 8% of the male population of the world are affected by a determined type of color vision disturbance, which varies from the partial to complete reduction of the ability to distinguish certain colors. A considerable amount of color blind people are able to live all life long without knowing they have color vision disabilities and abnormalities. Nowadays the evolution of information technology and computer science, specifically image processing techniques and computer graphics, can be fun...

  11. Physics of partially ionized plasmas

    CERN Document Server

    Krishan, Vinod

    2016-01-01

    Plasma is one of the four fundamental states of matter; the other three being solid, liquid and gas. Several components, such as molecular clouds, diffuse interstellar gas, the solar atmosphere, the Earth's ionosphere and laboratory plasmas, including fusion plasmas, constitute the partially ionized plasmas. This book discusses different aspects of partially ionized plasmas including multi-fluid description, equilibrium and types of waves. The discussion goes on to cover the reionization phase of the universe, along with a brief description of high discharge plasmas, tokomak plasmas and laser plasmas. Various elastic and inelastic collisions amongst the three particle species are also presented. In addition, the author demonstrates the novelty of partially ionized plasmas using many examples; for instance, in partially ionized plasma the magnetic induction is subjected to the ambipolar diffusion and the Hall effect, as well as the usual resistive dissipation. Also included is an observation of kinematic dynam...

  12. Partially massless fields during inflation

    Science.gov (United States)

    Baumann, Daniel; Goon, Garrett; Lee, Hayden; Pimentel, Guilherme L.

    2018-04-01

    The representation theory of de Sitter space allows for a category of partially massless particles which have no flat space analog, but could have existed during inflation. We study the couplings of these exotic particles to inflationary perturbations and determine the resulting signatures in cosmological correlators. When inflationary perturbations interact through the exchange of these fields, their correlation functions inherit scalings that cannot be mimicked by extra massive fields. We discuss in detail the squeezed limit of the tensor-scalar-scalar bispectrum, and show that certain partially massless fields can violate the tensor consistency relation of single-field inflation. We also consider the collapsed limit of the scalar trispectrum, and find that the exchange of partially massless fields enhances its magnitude, while giving no contribution to the scalar bispectrum. These characteristic signatures provide clean detection channels for partially massless fields during inflation.

  13. Blindness and severe visual impairment in pupils at schools for the blind in Burundi.

    Science.gov (United States)

    Ruhagaze, Patrick; Njuguna, Kahaki Kimani Margaret; Kandeke, Lévi; Courtright, Paul

    2013-01-01

    To determine the causes of childhood blindness and severe visual impairment in pupils attending schools for the blind in Burundi in order to assist planning for services in the country. All pupils attending three schools for the blind in Burundi were examined. A modified WHO/PBL eye examination record form for children with blindness and low vision was used to record the findings. Data was analyzed for those who became blind or severely visually impaired before the age of 16 years. Overall, 117 pupils who became visually impaired before 16 years of age were examined. Of these, 109 (93.2%) were blind or severely visually impaired. The major anatomical cause of blindness or severe visual impairment was cornea pathology/phthisis (23.9%), followed by lens pathology (18.3%), uveal lesions (14.7%) and optic nerve lesions (11.9%). In the majority of pupils with blindness or severe visual impairment, the underlying etiology of visual loss was unknown (74.3%). More than half of the pupils with lens related blindness had not had surgery; among those who had surgery, outcomes were generally poor. The causes identified indicate the importance of continuing preventive public health strategies, as well as the development of specialist pediatric ophthalmic services in the management of childhood blindness in Burundi. The geographic distribution of pupils at the schools for the blind indicates a need for community-based programs to identify and refer children in need of services.

  14. Introduction to partial differential equations

    CERN Document Server

    Greenspan, Donald

    2000-01-01

    Designed for use in a one-semester course by seniors and beginning graduate students, this rigorous presentation explores practical methods of solving differential equations, plus the unifying theory underlying the mathematical superstructure. Topics include basic concepts, Fourier series, second-order partial differential equations, wave equation, potential equation, heat equation, approximate solution of partial differential equations, and more. Exercises appear at the ends of most chapters. 1961 edition.

  15. Find Services for People Who Are Blind or Visually Impaired

    Science.gov (United States)

    ... Are Blind or Visually Impaired Find Services for People Who Are Blind or Visually Impaired Category All ... Territory Other (International) Organization Name Find Services for People Who Are Blind or Visually Impaired Browse All ...

  16. [Acrylic resin removable partial dentures].

    Science.gov (United States)

    de Baat, C; Witter, D J; Creugers, N H J

    2011-01-01

    An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of removable partial dentures, the acrylic resin removable partial denture has 3 favourable aspects: the economic aspect, its aesthetic quality and the ease with which it can be extended and adjusted. Disadvantages are an increased risk of caries developing, gingivitis, periodontal disease, denture stomatitis, alveolar bone reduction, tooth migration, triggering of the gag reflex and damage to the acrylic resin base. Present-day indications are ofa temporary or palliative nature or are motivated by economic factors. Special varieties of the acrylic resin removable partial denture are the spoon denture, the flexible denture fabricated of non-rigid acrylic resin, and the two-piece sectional denture. Furthermore, acrylic resin removable partial dentures can be supplied with clasps or reinforced by fibers or metal wires.

  17. Causes and emerging trends of childhood blindness: findings from schools for the blind in Southeast Nigeria.

    Science.gov (United States)

    Aghaji, Ada; Okoye, Obiekwe; Bowman, Richard

    2015-06-01

    To ascertain the causes severe visual impairment and blindness (SVI/BL) in schools for the blind in southeast Nigeria and to evaluate temporal trends. All children who developed blindness at schools for the blind in southeast Nigeria were examined. All the data were recorded on a WHO/Prevention of Blindness (WHO/PBL) form entered into a Microsoft Access database and transferred to STATA V.12.1 for analysis. To estimate temporal trends in causes of blindness, older (>15 years) children were compared with younger (≤15 years) children. 124 children were identified with SVI/BL. The most common anatomical site of blindness was the lens (33.9%). Overall, avoidable blindness accounted for 73.4% of all blindness. Exploring trends in SVI/BL between children ≤15 years of age and those >15 years old, this study shows a reduction in avoidable blindness but an increase in cortical visual impairment in the younger age group. The results from this study show a statistically significant decrease in avoidable blindness in children ≤15 years old. Corneal blindness appears to be decreasing but cortical visual impairment seems to be emerging in the younger age group. Appropriate strategies for the prevention of avoidable childhood blindness in Nigeria need to be developed and implemented. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  18. Parachute technique for partial penectomy

    Directory of Open Access Journals (Sweden)

    Fernando Korkes

    2010-04-01

    Full Text Available PURPOSE: Penile carcinoma is a rare but mutilating malignancy. In this context, partial penectomy is the most commonly applied approach for best oncological results. We herein propose a simple modification of the classic technique of partial penectomy, for better cosmetic and functional results. TECHNIQUE: If partial penectomy is indicated, the present technique can bring additional benefits. Different from classical technique, the urethra is spatulated only ventrally. An inverted "V" skin flap with 0.5 cm of extension is sectioned ventrally. The suture is performed with vicryl 4-0 in a "parachute" fashion, beginning from the ventral portion of the urethra and the "V" flap, followed by the "V" flap angles and than by the dorsal portion of the penis. After completion of the suture, a Foley catheter and light dressing are placed for 24 hours. CONCLUSIONS: Several complex reconstructive techniques have been previously proposed, but normally require specific surgical abilities, adequate patient selection and staged procedures. We believe that these reconstructive techniques are very useful in some specific subsets of patients. However, the technique herein proposed is a simple alternative that can be applied to all men after a partial penectomy, and takes the same amount of time as that in the classic technique. In conclusion, the "parachute" technique for penile reconstruction after partial amputation not only improves the appearance of the penis, but also maintains an adequate function.

  19. Ten years left to eliminate blinding trachoma

    Directory of Open Access Journals (Sweden)

    Haddad D.

    2010-09-01

    Full Text Available n 1997, the World Health Organization formed the Global Alliance to Eliminate Blinding Trachoma by 2020 (GET 2020, a coalition of governmental, non-governmental, research, and pharmaceutical partners. In 1998, the World Health Assembly urged member states to map blinding trachoma in endemic areas, implement the SAFE strategy (which stands for surgery for trichiasis, antibiotics, facial-cleanliness and environmental change, such as clean water and latrines and collaborate with the global alliance in its work to eliminate blinding trachoma.

  20. Blind image deconvolution methods and convergence

    CERN Document Server

    Chaudhuri, Subhasis; Rameshan, Renu

    2014-01-01

    Blind deconvolution is a classical image processing problem which has been investigated by a large number of researchers over the last four decades. The purpose of this monograph is not to propose yet another method for blind image restoration. Rather the basic issue of deconvolvability has been explored from a theoretical view point. Some authors claim very good results while quite a few claim that blind restoration does not work. The authors clearly detail when such methods are expected to work and when they will not. In order to avoid the assumptions needed for convergence analysis in the

  1. Reduced taste sensitivity in congenital blindness

    DEFF Research Database (Denmark)

    Gagnon, Lea; Kupers, Ron; Ptito, Maurice

    2013-01-01

    behavioral results showed that compared with the normal sighted, blind subjects have increased thresholds for taste detection and taste identification. This finding is at odds with the superior performance of congenitally blind subjects in several tactile, auditory and olfactory tasks. Our psychometric data...... thresholds of the 5 basic tastants in 13 congenitally blind and 13 sighted control subjects. Participants also answered several eating habits questionnaires, including the Food Neophobia Scale, the Food Variety Seeking Tendency Scale, the Intuitive Eating Scale, and the Body Awareness Questionnaire. Our...

  2. Finding Objects for Assisting Blind People.

    Science.gov (United States)

    Yi, Chucai; Flores, Roberto W; Chincha, Ricardo; Tian, Yingli

    2013-07-01

    Computer vision technology has been widely used for blind assistance, such as navigation and wayfinding. However, few camera-based systems are developed for helping blind or visually-impaired people to find daily necessities. In this paper, we propose a prototype system of blind-assistant object finding by camera-based network and matching-based recognition. We collect a dataset of daily necessities and apply Speeded-Up Robust Features (SURF) and Scale Invariant Feature Transform (SIFT) feature descriptors to perform object recognition. Experimental results demonstrate the effectiveness of our prototype system.

  3. Do students with higher self-efficacy exhibit greater and more diverse scientific inquiry skills: An exploratory investigation in "River City", a multi-user virtual environment

    Science.gov (United States)

    Ketelhut, Diane Jass

    In this thesis, I conduct an exploratory study to investigate the relationship between students' self-efficacy on entry into authentic scientific activity and the scientific inquiry behaviors they employ while engaged in that process, over time. Scientific inquiry has been a major standard in most science education policy doctrines for the past two decades and is exemplified by activities such as making observations, formulating hypotheses, gathering and analyzing data, and forming conclusions from that data. The self-efficacy literature, however, indicates that self-efficacy levels affect perseverance and engagement. This study investigated the relationship between these two constructs. The study is conducted in a novel setting, using an innovative science curriculum delivered through an interactive computer technology that recorded each student's conversations, movements, and activities while behaving as a practicing scientist in a "virtual world" called River City. River City is a Multi-User Virtual Environment designed to engage students in a collaborative scientific inquiry-based learning experience. As a result, I was able to follow students' moment-by-moment choices of behavior while they were behaving as scientists. I collected data on students' total scientific inquiry behaviors over three visits to River City, as well as the number of sources from which they gathered their scientific data. I analyzed my longitudinal data on the 96 seventh-graders using individual growth modeling. I found that self-efficacy played a role in the number of data-gathering behaviors students engaged in initially, with high self-efficacy students engaging in more data gathering than students with low self-efficacy. However, the impact of student self-efficacy on rate of change in data gathering behavior differed by gender; by the end of the study, student self-efficacy did not impact data gathering. In addition, students' level of self-efficacy did not affect how many different

  4. Blindness of Johann Sebastian Bach.

    Science.gov (United States)

    Tarkkanen, Ahti

    2013-03-01

    Johann Sebastian Bach (1685-1750) was one of the greatest composers of all time. Apart from performing as a brilliant organist, he composed over 1.100 works in almost every musical genre. He was known as a hardworking, deeply Christian person, who had to support his family of 20 children and many students staying at his home. At the age of 64 years, his vision started to decline. Old biographies claim that it was the result of overstressing his vision in poor illumination. By persuasion of his friends, he had his both eyes operated by a travelling British eye surgeon. A cataract couching was performed. After surgery, Bach was totally blind and unable to play an organ, compose or direct choirs and orchestras. He was confined to bed and suffering from immense pain of the eyes and the body. He died <4 months after surgery. In this paper, as the plausible diagnosis, intractable glaucoma because of pupillary block or secondary to phacoanaphylactic endophthalmitis is suggested. © 2012 The Author. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.

  5. Partial Transposition on Bipartite System

    International Nuclear Information System (INIS)

    Xi-Jun, Ren; Yong-Jian, Han; Yu-Chun, Wu; Guang-Can, Guo

    2008-01-01

    Many properties of partial transposition are unclear as yet. Here we carefully consider the number of the negative eigenvalues of ρ T (ρ's partial transposition) when ρ is a two-partite state. There is strong evidence to show that the number of negative eigenvalues of ρ T is N(N − 1)/2 at most when ρ is a state in Hilbert space C N C N . For the special case, the 2 × 2 system, we use this result to give a partial proof of the conjecture |ρ T | T ≥ 0. We find that this conjecture is strongly connected with the entanglement of the state corresponding to the negative eigenvalue of ρ T or the negative entropy of ρ

  6. Partial volume effect in MRI

    International Nuclear Information System (INIS)

    Maeda, Munehiro; Yoshiya, Kazuhiko; Suzuki, Eiji

    1989-01-01

    According to the direction and the thickness of the imaging slice in tomography, the border between the tissues becomes unclear (partial volume effect). In the present MRI experiment, we examined border area between fat and water components using phantom in order to investigate the partial volume effect in MRI. In spin echo sequences, the intensity of the border area showed a linear relationship with composition of fat and water. Whereas, in inversion recovery and field echo sequences, we found the parameters to produce an extremely low intensity area at the border region between fat and water. This low intensity area was explained by cancellation of NMR signals from fat and water due to the difference in the direction of magnetic vectors. Clinically, partial volume effect can cause of mis-evaluation of walls, small nodules, tumor capsules and the tumor invasion in the use of inversion recovery and field echo sequences. (author)

  7. Partially composite Goldstone Higgs boson

    DEFF Research Database (Denmark)

    Alanne, Tommi; Franzosi, Diogo Buarque; Frandsen, Mads T.

    2017-01-01

    We consider a model of dynamical electroweak symmetry breaking with a partially composite Goldstone Higgs boson. The model is based on a strongly interacting fermionic sector coupled to a fundamental scalar sector via Yukawa interactions. The SU(4)×SU(4) global symmetry of these two sectors...... is broken to a single SU(4) via Yukawa interactions. Electroweak symmetry breaking is dynamically induced by condensation due to the strong interactions in the new fermionic sector which further breaks the global symmetry SU(4)→Sp(4). The Higgs boson arises as a partially composite state which is an exact...... Goldstone boson in the limit where SM interactions are turned off. Terms breaking the SU(4) global symmetry explicitly generate a mass for the Goldstone Higgs boson. The model realizes in different limits both (partially) composite Higgs and (bosonic) technicolor models, thereby providing a convenient...

  8. Landsliding in partially saturated materials

    Science.gov (United States)

    Godt, J.W.; Baum, R.L.; Lu, N.

    2009-01-01

    [1] Rainfall-induced landslides are pervasive in hillslope environments around the world and among the most costly and deadly natural hazards. However, capturing their occurrence with scientific instrumentation in a natural setting is extremely rare. The prevailing thinking on landslide initiation, particularly for those landslides that occur under intense precipitation, is that the failure surface is saturated and has positive pore-water pressures acting on it. Most analytic methods used for landslide hazard assessment are based on the above perception and assume that the failure surface is located beneath a water table. By monitoring the pore water and soil suction response to rainfall, we observed shallow landslide occurrence under partially saturated conditions for the first time in a natural setting. We show that the partially saturated shallow landslide at this site is predictable using measured soil suction and water content and a novel unified effective stress concept for partially saturated earth materials. Copyright 2009 by the American Geophysical Union.

  9. Basic linear partial differential equations

    CERN Document Server

    Treves, Francois

    1975-01-01

    Focusing on the archetypes of linear partial differential equations, this text for upper-level undergraduates and graduate students features most of the basic classical results. The methods, however, are decidedly nontraditional: in practically every instance, they tend toward a high level of abstraction. This approach recalls classical material to contemporary analysts in a language they can understand, as well as exploiting the field's wealth of examples as an introduction to modern theories.The four-part treatment covers the basic examples of linear partial differential equations and their

  10. Elements of partial differential equations

    CERN Document Server

    Sneddon, Ian Naismith

    1957-01-01

    Geared toward students of applied rather than pure mathematics, this volume introduces elements of partial differential equations. Its focus is primarily upon finding solutions to particular equations rather than general theory.Topics include ordinary differential equations in more than two variables, partial differential equations of the first and second orders, Laplace's equation, the wave equation, and the diffusion equation. A helpful Appendix offers information on systems of surfaces, and solutions to the odd-numbered problems appear at the end of the book. Readers pursuing independent st

  11. Iterated Gate Teleportation and Blind Quantum Computation.

    Science.gov (United States)

    Pérez-Delgado, Carlos A; Fitzsimons, Joseph F

    2015-06-05

    Blind quantum computation allows a user to delegate a computation to an untrusted server while keeping the computation hidden. A number of recent works have sought to establish bounds on the communication requirements necessary to implement blind computation, and a bound based on the no-programming theorem of Nielsen and Chuang has emerged as a natural limiting factor. Here we show that this constraint only holds in limited scenarios, and show how to overcome it using a novel method of iterated gate teleportations. This technique enables drastic reductions in the communication required for distributed quantum protocols, extending beyond the blind computation setting. Applied to blind quantum computation, this technique offers significant efficiency improvements, and in some scenarios offers an exponential reduction in communication requirements.

  12. Global Transsaccadic Change Blindness During Scene Perception

    National Research Council Canada - National Science Library

    Henderson, John

    2003-01-01

    .... The results from two experiments demonstrated a global transsaccadic change-blindness effect, suggesting that point-by-point visual representations are not functional across saccades during complex scene perception. Ahstract.

  13. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... Scientist Video Series Why can’t you see colors well in the dark? Do fish have eyelids? ... video series. Dr. Sheldon Miller answers questions about color blindness, whether it can be treated, and how ...

  14. Short communication: Cerebral Malaria Complicated by Blindness ...

    African Journals Online (AJOL)

    grade intermittent fever associated with multiple convulsions and prolonged coma. He regained consciousness after 12 days of treatment with intravenous quinine but was found to have blindness, sensory‑neural deafness and extrapyramidal ...

  15. Congenital blindness improves semantic and episodic memory.

    Science.gov (United States)

    Pasqualotto, Achille; Lam, Jade S Y; Proulx, Michael J

    2013-05-01

    Previous studies reported that congenitally blind people possess superior verb-generation skills. Here we tested the impact of blindness on capacity and the fidelity of semantic memory by using a false memory paradigm. In the Deese-Roediger-McDermott paradigm, participants study lists of words that are all semantically related to a lure that is not presented. Subsequently, participants frequently recall the missing lure. We found that congenitally blind participants have enhanced memory performance for recalling the presented words and reduced false memories for the lure. The dissociation of memory capacity and fidelity provides further evidence for enhanced verbal ability in the blind, supported by their broader structural and functional brain reorganisation. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Universal blind quantum computation for hybrid system

    Science.gov (United States)

    Huang, He-Liang; Bao, Wan-Su; Li, Tan; Li, Feng-Guang; Fu, Xiang-Qun; Zhang, Shuo; Zhang, Hai-Long; Wang, Xiang

    2017-08-01

    As progress on the development of building quantum computer continues to advance, first-generation practical quantum computers will be available for ordinary users in the cloud style similar to IBM's Quantum Experience nowadays. Clients can remotely access the quantum servers using some simple devices. In such a situation, it is of prime importance to keep the security of the client's information. Blind quantum computation protocols enable a client with limited quantum technology to delegate her quantum computation to a quantum server without leaking any privacy. To date, blind quantum computation has been considered only for an individual quantum system. However, practical universal quantum computer is likely to be a hybrid system. Here, we take the first step to construct a framework of blind quantum computation for the hybrid system, which provides a more feasible way for scalable blind quantum computation.

  17. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of sight, ...

  18. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... t you see colors well in the dark? Do fish have eyelids? Why does saltwater sting your ... treated, and how people become color blind. What do my eyes do when I’m sleeping? Click ...

  19. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... Information Optical Illusions Printables Ask a Scientist Video Series Why can’t you see colors well in ... and more with our Ask a Scientist video series. Dr. Sheldon Miller answers questions about color blindness, ...

  20. Ask a Scientist: What is Color Blindness?

    Medline Plus

    Full Text Available ... NIH), the National Eye Institute’s mission is to “conduct and support research, training, health information dissemination, and other programs with respect to blinding eye diseases, visual disorders, mechanisms of visual function, preservation of ...