Performance analyses and improvements for the IEEE 802.15.4 CSMA/CA scheme with heterogeneous buffered conditions.

PubMed

Zhu, Jianping; Tao, Zhengsu; Lv, Chunfeng

2012-01-01

Studies of the IEEE 802.15.4 Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) scheme have been received considerable attention recently, with most of these studies focusing on homogeneous or saturated traffic. Two novel transmission schemes-OSTS/BSTS (One Service a Time Scheme/Bulk Service a Time Scheme)-are proposed in this paper to improve the behaviors of time-critical buffered networks with heterogeneous unsaturated traffic. First, we propose a model which contains two modified semi-Markov chains and a macro-Markov chain combined with the theory of M/G/1/K queues to evaluate the characteristics of these two improved CSMA/CA schemes, in which traffic arrivals and accessing packets are bestowed with non-preemptive priority over each other, instead of prioritization. Then, throughput, packet delay and energy consumption of unsaturated, unacknowledged IEEE 802.15.4 beacon-enabled networks are predicted based on the overall point of view which takes the dependent interactions of different types of nodes into account. Moreover, performance comparisons of these two schemes with other non-priority schemes are also proposed. Analysis and simulation results show that delay and fairness of our schemes are superior to those of other schemes, while throughput and energy efficiency are superior to others in more heterogeneous situations. Comprehensive simulations demonstrate that the analysis results of these models match well with the simulation results.

Collision avoidance in TV white spaces: a cross-layer design approach for cognitive radio networks

NASA Astrophysics Data System (ADS)

Foukalas, Fotis; Karetsos, George T.

2015-07-01

One of the most promising applications of cognitive radio networks (CRNs) is the efficient exploitation of TV white spaces (TVWSs) for enhancing the performance of wireless networks. In this paper, we propose a cross-layer design (CLD) of carrier sense multiple access with collision avoidance (CSMA/CA) mechanism at the medium access control (MAC) layer with spectrum sensing (SpSe) at the physical layer, for identifying the occupancy status of TV bands. The proposed CLD relies on a Markov chain model with a state pair containing both the SpSe and the CSMA/CA from which we derive the collision probability and the achievable throughput. Analytical and simulation results are obtained for different collision avoidance and SpSe implementation scenarios by varying the contention window, back off stage and probability of detection. The obtained results depict the achievable throughput under different collision avoidance and SpSe implementation scenarios indicating thereby the performance of collision avoidance in TVWSs-based CRNs.

Strategies for Optimal MAC Parameters Tuning in IEEE 802.15.6 Wearable Wireless Sensor Networks.

PubMed

Alam, Muhammad Mahtab; Ben Hamida, Elyes

2015-09-01

Wireless body area networks (WBAN) has penetrated immensely in revolutionizing the classical heath-care system. Recently, number of WBAN applications has emerged which introduce potential limits to existing solutions. In particular, IEEE 802.15.6 standard has provided great flexibility, provisions and capabilities to deal emerging applications. In this paper, we investigate the application-specific throughput analysis by fine-tuning the physical (PHY) and medium access control (MAC) parameters of the IEEE 802.15.6 standard. Based on PHY characterizations in narrow band, at the MAC layer, carrier sense multiple access collision avoidance (CSMA/CA) and scheduled access protocols are extensively analyzed. It is concluded that, IEEE 802.15.6 standard can satisfy most of the WBANs applications throughput requirements by maximum achieving 680 Kbps. However, those emerging applications which require high quality audio or video transmissions, standard is not able to meet their constraints. Moreover, delay, energy efficiency and successful packet reception are considered as key performance metrics for comparing the MAC protocols. CSMA/CA protocol provides the best results to meet the delay constraints of medical and non-medical WBAN applications. Whereas, the scheduled access approach, performs very well both in energy efficiency and packet reception ratio.

Adjacency Matrix-Based Transmit Power Allocation Strategies in Wireless Sensor Networks

PubMed Central

Consolini, Luca; Medagliani, Paolo; Ferrari, Gianluigi

2009-01-01

In this paper, we present an innovative transmit power control scheme, based on optimization theory, for wireless sensor networks (WSNs) which use carrier sense multiple access (CSMA) with collision avoidance (CA) as medium access control (MAC) protocol. In particular, we focus on schemes where several remote nodes send data directly to a common access point (AP). Under the assumption of finite overall network transmit power and low traffic load, we derive the optimal transmit power allocation strategy that minimizes the packet error rate (PER) at the AP. This approach is based on modeling the CSMA/CA MAC protocol through a finite state machine and takes into account the network adjacency matrix, depending on the transmit power distribution and determining the network connectivity. It will be then shown that the transmit power allocation problem reduces to a convex constrained minimization problem. Our results show that, under the assumption of low traffic load, the power allocation strategy, which guarantees minimal delay, requires the maximization of network connectivity, which can be equivalently interpreted as the maximization of the number of non-zero entries of the adjacency matrix. The obtained theoretical results are confirmed by simulations for unslotted Zigbee WSNs. PMID:22346705

Air Traffic Control Improvement Using Prioritized CSMA

NASA Technical Reports Server (NTRS)

Robinson, Daryl C.

2001-01-01

Version 7 simulations of the industry-standard network simulation software "OPNET" are presented of two applications of the Aeronautical Telecommunications Network (ATN), Controller Pilot Data Link Communications (CPDLC) and Automatic Dependent Surveillance-Broadcast mode (ADS-B), over VHF Data Link mode 2 (VDL-2). Communication is modeled for air traffic between just three cities. All aircraft are assumed to have the same equipage. The simulation involves Air Traffic Control (ATC) ground stations and 105 aircraft taking off, flying realistic free-flight trajectories, and landing in a 24-hr period. All communication is modeled as unreliable. Collision-less, prioritized carrier sense multiple access (CSMA) is successfully tested. The statistics presented include latency, queue length, and packet loss. This research may show that a communications system simpler than the currently accepted standard envisioned may not only suffice, but also surpass performance of the standard at a lower cost of deployment.

Scalable Lunar Surface Networks and Adaptive Orbit Access

NASA Technical Reports Server (NTRS)

Wang, Xudong

2015-01-01

Teranovi Technologies, Inc., has developed innovative network architecture, protocols, and algorithms for both lunar surface and orbit access networks. A key component of the overall architecture is a medium access control (MAC) protocol that includes a novel mechanism of overlaying time division multiple access (TDMA) and carrier sense multiple access with collision avoidance (CSMA/CA), ensuring scalable throughput and quality of service. The new MAC protocol is compatible with legacy Institute of Electrical and Electronics Engineers (IEEE) 802.11 networks. Advanced features include efficiency power management, adaptive channel width adjustment, and error control capability. A hybrid routing protocol combines the advantages of ad hoc on-demand distance vector (AODV) routing and disruption/delay-tolerant network (DTN) routing. Performance is significantly better than AODV or DTN and will be particularly effective for wireless networks with intermittent links, such as lunar and planetary surface networks and orbit access networks.

Performance Analysis of IEEE 802.15.6 CSMA/CA Protocol for WBAN Medical Scenario through DTMC Model.

PubMed

Kumar, Vivek; Gupta, Bharat

2016-12-01

The newly drafted IEEE 802.15.6 standard for Wireless Body Area Networks (WBAN) has been concentrating on a numerous medical and non-medical applications. Such short range wireless communication standard offers ultra-low power consumption with variable data rates from few Kbps to Mbps in, on or around the proximity of the human body. In this paper, the performance analysis of carrier sense multiple access with collision avoidance (CSMA/CA) scheme based on IEEE 802.15.6 standard in terms of throughput, reliability, clear channel assessment (CCA) failure probability, packet drop probability, and end-to-end delay has been presented. We have developed a discrete-time Markov chain (DTMC) to significantly evaluate the performances of IEEE 802.15.6 CSMA/CA under non-ideal channel condition having saturated traffic condition including node wait time and service time. We also visualize that, as soon as the payload length increases the CCA failure probability increases, which results in lower node's reliability. Also, we have calculated the end-to-end delay in order to prioritize the node wait time cause by backoff and retransmission. The user priority (UP) wise DTMC analysis has been performed to show the importance of the standard especially for medical scenario.

Research on an uplink carrier sense multiple access algorithm of large indoor visible light communication networks based on an optical hard core point process.

PubMed

Nan, Zhufen; Chi, Xuefen

2016-12-20

The IEEE 802.15.7 protocol suggests that it could coordinate the channel access process based on the competitive method of carrier sensing. However, the directionality of light and randomness of diffuse reflection would give rise to a serious imperfect carrier sense (ICS) problem [e.g., hidden node (HN) problem and exposed node (EN) problem], which brings great challenges in realizing the optical carrier sense multiple access (CSMA) mechanism. In this paper, the carrier sense process implemented by diffuse reflection light is modeled as the choice of independent sets. We establish an ICS model with the presence of ENs and HNs for the multi-point to multi-point visible light communication (VLC) uplink communications system. Considering the severe optical ICS problem, an optical hard core point process (OHCPP) is developed, which characterizes the optical CSMA for the indoor VLC uplink communications system. Due to the limited coverage of the transmitted optical signal, in our OHCPP, the ENs within the transmitters' carrier sense region could be retained provided that they could not corrupt the ongoing communications. Moreover, because of the directionality of both light emitting diode (LED) transmitters and receivers, theoretical analysis of the HN problem becomes difficult. In this paper, we derive the closed-form expression for approximating the outage probability and transmission capacity of VLC networks with the presence of HNs and ENs. Simulation results validate the analysis and also show the existence of an optimal physical carrier-sensing threshold that maximizes the transmission capacity for a given emission angle of LED.

Link Scheduling Algorithm with Interference Prediction for Multiple Mobile WBANs

PubMed Central

Le, Thien T. T.

2017-01-01

As wireless body area networks (WBANs) become a key element in electronic healthcare (e-healthcare) systems, the coexistence of multiple mobile WBANs is becoming an issue. The network performance is negatively affected by the unpredictable movement of the human body. In such an environment, inter-WBAN interference can be caused by the overlapping transmission range of nearby WBANs. We propose a link scheduling algorithm with interference prediction (LSIP) for multiple mobile WBANs, which allows multiple mobile WBANs to transmit at the same time without causing inter-WBAN interference. In the LSIP, a superframe includes the contention access phase using carrier sense multiple access with collision avoidance (CSMA/CA) and the scheduled phase using time division multiple access (TDMA) for non-interfering nodes and interfering nodes, respectively. For interference prediction, we define a parameter called interference duration as the duration during which disparate WBANs interfere with each other. The Bayesian model is used to estimate and classify the interference using a signal to interference plus noise ratio (SINR) and the number of neighboring WBANs. The simulation results show that the proposed LSIP algorithm improves the packet delivery ratio and throughput significantly with acceptable delay. PMID:28956827

Modelling high data rate communication network access protocol

NASA Technical Reports Server (NTRS)

Khanna, S.; Foudriat, E. C.; Paterra, Frank; Maly, Kurt J.; Overstreet, C. Michael

1990-01-01

Modeling of high data rate communication systems is different from the low data rate systems. Three simulations were built during the development phase of Carrier Sensed Multiple Access/Ring Network (CSMA/RN) modeling. The first was a model using SIMCRIPT based upon the determination and processing of each event at each node. The second simulation was developed in C based upon isolating the distinct object that can be identified as the ring, the message, the node, and the set of critical events. The third model further identified the basic network functionality by creating a single object, the node which includes the set of critical events which occur at the node. The ring structure is implicit in the node structure. This model was also built in C. Each model is discussed and their features compared. It should be stated that the language used was mainly selected by the model developer because of his past familiarity. Further the models were not built with the intent to compare either structure or language but because the complexity of the problem and initial results contained obvious errors, so alternative models were built to isolate, determine, and correct programming and modeling errors. The CSMA/RN protocol is discussed in sufficient detail to understand modeling complexities. Each model is described along with its features and problems. The models are compared and concluding observations and remarks are presented.

Extremely high data-rate, reliable network systems research

NASA Technical Reports Server (NTRS)

Foudriat, E. C.; Maly, Kurt J.; Mukkamala, R.; Murray, Nicholas D.; Overstreet, C. Michael

1990-01-01

Significant progress was made over the year in the four focus areas of this research group: gigabit protocols, extensions of metropolitan protocols, parallel protocols, and distributed simulations. Two activities, a network management tool and the Carrier Sensed Multiple Access Collision Detection (CSMA/CD) protocol, have developed to the point that a patent is being applied for in the next year; a tool set for distributed simulation using the language SIMSCRIPT also has commercial potential and is to be further refined. The year's results for each of these areas are summarized and next year's activities are described.

Chondroitin sulfate-g-poly(ϵ-caprolactone) co-polymer aggregates as potential targeting drug carriers.

PubMed

Wang, Li-Fang; Ni, Hsiao-Chen; Lin, Chia-Chan

2012-01-01

The aim of this study is to delineate the effect of various amounts of hydrophobic polycaprolactone (PCL) grafted onto three different degrees of methacrylated chondroitin sulfate (CSMA) on chemical-physical properties. The co-polymers were prepared by reacting the modified PCL and the hydrophilic CSMA via a radical reaction (CSMA-PCL). The effect of degree of methacrylation of CSMA and feed ratio between CSMA and PCL on compositions and critical micelle concentrations was systematically studied. The PCL composition of the CSMA-PCL was characterized by (1)H-NMR and FT-IR. The hydrodynamic diameters and morphologies of CSMA-PCL micelles were studied by DLS and TEM. Critical micelle concentrations were determined using pyrene as a probe. Taking one of the CSMA-PCL micelles as an example, a cancer-mediated ligand, folic acid, was linked to the surface. The cellular uptake of the folic acid-linked CSMA-PCL in folate-receptor-overexpressing KB cells was studied by confocal laser scanning microscopy and flow cytometry.

Sandia Compact Sensor Node (SCSN) v. 1.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

HARRINGTON, JOHN

2009-01-07

The SCSN communication protocol is implemented in software and incorporates elements of Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Carrier Sense Multiple Access (CSMA) to reduce radio message collisions, latency, and power consumption. Alarm messages are expeditiously routed to a central node as a 'star' network with minimum overhead. Other messages can be routed along network links between any two nodes so that peer-to-peer communication is possible. Broadcast messages can be composed that flood the entire network or just specific portions with minimal radio traffic and latency. Two-way communication with sensor nodes, which sleep most ofmore » the time to conserve battery life, can occur at seven second intervals. SCSN software also incorporates special algorithms to minimize superfluous radio traffic that can result from excessive intrusion alarm messages. A built-in seismic detector is implemented with a geophone and software that distinguishes between pedestrian and vehicular targets. Other external sensors can be attached to a SCSN using supervised interface lines that are controlled by software. All software is written in the ANSI C language for ease of development, maintenance, and portability.« less

Design Sketches For Optical Crossbar Switches Intended For Large-Scale Parallel Processing Applications

NASA Astrophysics Data System (ADS)

Hartmann, Alfred; Redfield, Steve

1989-04-01

This paper discusses design of large-scale (1000x 1000) optical crossbar switching networks for use in parallel processing supercom-puters. Alternative design sketches for an optical crossbar switching network are presented using free-space optical transmission with either a beam spreading/masking model or a beam steering model for internodal communications. The performances of alternative multiple access channel communications protocol-unslotted and slotted ALOHA and carrier sense multiple access (CSMA)-are compared with the performance of the classic arbitrated bus crossbar of conventional electronic parallel computing. These comparisons indicate an almost inverse relationship between ease of implementation and speed of operation. Practical issues of optical system design are addressed, and an optically addressed, composite spatial light modulator design is presented for fabrication to arbitrarily large scale. The wide range of switch architecture, communications protocol, optical systems design, device fabrication, and system performance problems presented by these design sketches poses a serious challenge to practical exploitation of highly parallel optical interconnects in advanced computer designs.

Implementation of a Cross-Layer Sensing Medium-Access Control Scheme.

PubMed

Su, Yishan; Fu, Xiaomei; Han, Guangyao; Xu, Naishen; Jin, Zhigang

2017-04-10

In this paper, compressed sensing (CS) theory is utilized in a medium-access control (MAC) scheme for wireless sensor networks (WSNs). We propose a new, cross-layer compressed sensing medium-access control (CL CS-MAC) scheme, combining the physical layer and data link layer, where the wireless transmission in physical layer is considered as a compress process of requested packets in a data link layer according to compressed sensing (CS) theory. We first introduced using compressive complex requests to identify the exact active sensor nodes, which makes the scheme more efficient. Moreover, because the reconstruction process is executed in a complex field of a physical layer, where no bit and frame synchronizations are needed, the asynchronous and random requests scheme can be implemented without synchronization payload. We set up a testbed based on software-defined radio (SDR) to implement the proposed CL CS-MAC scheme practically and to demonstrate the validation. For large-scale WSNs, the simulation results show that the proposed CL CS-MAC scheme provides higher throughput and robustness than the carrier sense multiple access (CSMA) and compressed sensing medium-access control (CS-MAC) schemes.

Microcomputer Applications with PC LAN (Local Area Network) in Battleships.

DTIC Science & Technology

1988-12-01

NETWORKS 5 C. TRANSMISSION TECHNIQUES 6 D. MEDIUM ACCESS CONTROL METHODS 6 1. CSMA CD 6 2. Control Token 7 3. Slotted Ring 7 E...network model in the Turkish Battleships will employ the broadband technique. D. MEDIUM ACCESS CONTROL METHODS The access method is one of the most...better performance at heavier loads. 3. Slotted Ring This method is used with a ring network. The ring is initialized to contain a fixed number of

High Performance Asynchronous Limited Sensing Algorithms for CSMA and CSMA-CD Channels.

DTIC Science & Technology

1985-03-01

for CSM and CSMA-CD Channels" M. Geargiopoulos L. Merakos P. Papantoni-Kazakos- Technical Report UCT/ DEECS /TR-85-2 Mrh1985 iDISTRIBUTION STAEmEN 2j C...Perforance Asynchronous Limited Sensing Algoit~5 forCSMAandCSMA-CD Channels" M1. Georgiop0 ul 0 5 L. Merakos P. PaPantoni-.Kazakos Technical Report UCT/ DEECS ...SCHEDULE unlimited. 4 PERFORMING ORGANiZATION REPORT NUMBERIS) 5. MONITORING ORGANIZATION REPORT NUMBERIS" UCT/ DEECS /TR-85-2 SR-TR. 85-0 398 6& NAME OF

Resource sharing on CSMA/CD networks in the presence of noise. M.S. Thesis

NASA Technical Reports Server (NTRS)

Dinschel, Duane Edward

1987-01-01

Resource sharing on carrier sense multiple access with collision detection (CSMA/CD) networks can be accomplished by using window-control algorithms for bus contention. The window-control algorithms are designed to grant permission to transmit to the station with the minimum contention parameter. Proper operation of the window-control algorithm requires that all stations sense the same state of the newtork in each contention slot. Noise causes the state of the network to appear as a collision. False collisions can cause the window-control algorithm to terminate without isolating any stations. A two-phase window-control protocol and approximate recurrence equation with noise as a parameter to improve the performance of the window-control algorithms in the presence of noise are developed. The results are compared through simulation, with the approximate recurrence equation yielding the best overall performance. Noise is even a bigger problem when it is not detected by all stations. In such cases it is possible for the window boundaries of the contending stations to become out of phase. Consequently, it is possible to isolate a station other than the one with the minimum contention parameter. To guarantee proper isolation of the minimum, a broadcast phase must be added after the termination of the algorithm. The protocol required to correct the window-control algorithm when noise is not detected by all stations is discussed.

The copolymer of Poly(2-dimethylaminoethyl methacrylate) and methacrylated chondroitin sulfate with low cytotoxicity for gene delivery.

PubMed

Lo, Yu-Lun; Wang, Yao-Sheng; Wang, Li-Fang

2013-11-01

Poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) is one of the most potent synthetic nonviral gene-delivery vectors because of its high transfection efficiency. However, the cytotoxicity of PDMAEMA is a major concern for its clinical applications. An anionic crosslinker is synthesized based on a natural polysaccharide, chondroitin sulfate (CS), by introducing methacrylate groups (CSMA). By systematically adjusting the substitution degree of methacrylation on CS and the weight percent of CSMA and PDMAEMA, sol-type copolymers are obtained as a gene-delivery vector. The combination of CS and PDMAEMA is expected not only to reduce the cytotoxicity of PDMAEMA, but also to facilitate better transfection efficiency than PDMAEMA because of the recognition of CS by CD44 receptors on cell surfaces. Two CSMA-modified PDMAEMA copolymers with different CSMA constituents are selected and their polyplexes prepared with plasmid DNA. The cytotoxicity and gene transfection efficiency of the polyplexes are tested and compared with those of PDMAEMA/pDNA. The copolymers of CSMA and PDMAEMA show significantly improved cell viability as compared with PDMAEMA. Their formed polyplexes with pDNA also show lower cytotoxicity than does PDMAEMA/pDNA. The transfection efficiency remarkably increases as the CSMA-modified PDMAEMA/pDNA polyplex is prepared at a weight ratio of 2.4. The internalization mechanism of CSMA-modified PDMAEMA/pDNA in HEK 293T cells is mainly based on caveolae-mediated endocytosis. However, both caveolae-mediated and CD44-mediated endocytosis mechanisms are involved in U87 cells. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Performance Optimization of Priority Assisted CSMA/CA Mechanism of 802.15.6 under Saturation Regime

PubMed Central

Shakir, Mustafa; Rehman, Obaid Ur; Rahim, Mudassir; Alrajeh, Nabil; Khan, Zahoor Ali; Khan, Mahmood Ashraf; Niaz, Iftikhar Azim; Javaid, Nadeem

2016-01-01

Due to the recent development in the field of Wireless Sensor Networks (WSNs), the Wireless Body Area Networks (WBANs) have become a major area of interest for the developers and researchers. Human body exhibits postural mobility due to which distance variation occurs and the status of connections amongst sensors change time to time. One of the major requirements of WBAN is to prolong the network lifetime without compromising on other performance measures, i.e., delay, throughput and bandwidth efficiency. Node prioritization is one of the possible solutions to obtain optimum performance in WBAN. IEEE 802.15.6 CSMA/CA standard splits the nodes with different user priorities based on Contention Window (CW) size. Smaller CW size is assigned to higher priority nodes. This standard helps to reduce delay, however, it is not energy efficient. In this paper, we propose a hybrid node prioritization scheme based on IEEE 802.15.6 CSMA/CA to reduce energy consumption and maximize network lifetime. In this scheme, optimum performance is achieved by node prioritization based on CW size as well as power in respective user priority. Our proposed scheme reduces the average back off time for channel access due to CW based prioritization. Additionally, power based prioritization for a respective user priority helps to minimize required number of retransmissions. Furthermore, we also compare our scheme with IEEE 802.15.6 CSMA/CA standard (CW assisted node prioritization) and power assisted node prioritization under postural mobility in WBAN. Mathematical expressions are derived to determine the accurate analytical model for throughput, delay, bandwidth efficiency, energy consumption and life time for each node prioritization scheme. With the intention of analytical model validation, we have performed the simulations in OMNET++/MIXIM framework. Analytical and simulation results show that our proposed hybrid node prioritization scheme outperforms other node prioritization schemes in terms of average network delay, average throughput, average bandwidth efficiency and network lifetime. PMID:27598167

The light-harvesting antenna of Chlorobium tepidum: interactions between the FMO protein and the major chlorosome protein CsmA studied by surface plasmon resonance.

PubMed

Pedersen, Marie Østergaard; Borch, Jonas; Højrup, Peter; Cox, Raymond P; Miller, Mette

2006-09-01

Green sulfur bacteria possess two external light-harvesting antenna systems, the chlorosome and the FMO protein, which participate in a sequential energy transfer to the reaction centers embedded in the cytoplasmic membrane. However, little is known about the physical interaction between these two antenna systems. We have studied the interaction between the major chlorosome protein, CsmA, and the FMO protein in Chlorobium tepidum using surface plasmon resonance (SPR). Our results show an interaction between the FMO protein and an immobilized synthetic peptide corresponding to 17 amino acids at the C terminal of CsmA. This interaction is dependent on the presence of a motif comprising six amino acids that are highly conserved in all the currently available CsmA protein sequences.

Q-Learning and p-persistent CSMA based rendezvous protocol for cognitive radio networks operating with shared spectrum activity

NASA Astrophysics Data System (ADS)

Watson, Clifton L.; Biswas, Subir

2014-06-01

With an increasing demand for spectrum, dynamic spectrum access (DSA) has been proposed as viable means for providing the flexibility and greater access to spectrum necessary to meet this demand. Within the DSA concept, unlicensed secondary users temporarily "borrow" or access licensed spectrum, while respecting the licensed primary user's rights to that spectrum. As key enablers for DSA, cognitive radios (CRs) are based on software-defined radios which allow them to sense, learn, and adapt to the spectrum environment. These radios can operate independently and rapidly switch channels. Thus, the initial setup and maintenance of cognitive radio networks are dependent upon the ability of CR nodes to find each other, in a process known as rendezvous, and create a link on a common channel for the exchange of data and control information. In this paper, we propose a novel rendezvous protocol, known as QLP, which is based on Q-learning and the p-persistent CSMA protocol. With the QLP protocol, CR nodes learn which channels are best for rendezvous and thus adapt their behavior to visit those channels more frequently. We demonstrate through simulation that the QLP protocol provides a rendevous capability for DSA environments with different dynamics of PU activity, while attempting to achieve the following performance goals: (1) minimize the average time-to-rendezvous, (2) maximize system throughput, (3) minimize primary user interference, and (4) minimize collisions among CR nodes.

Dual Purpose Simulation: New Data Link Test and Comparison With VDL-2

NASA Technical Reports Server (NTRS)

Robinson, Daryl C.

2005-01-01

While the results of this paper are similar to those of previous research, in this paper technical difficulties present there are eliminated, producing better results, enabling one to more readily see the benefits of Prioritized CSMA (PCSMA). A new analysis section also helps to generalize this research so that it is not limited to exploration of the new concept of PCSMA. Commercially available network simulation software, OPNET version 7.0, simulations are presented involving an important application of the Aeronautical Telecommunications Network (ATN), Controller Pilot Data Link Communications (CPDLC) over the Very High Frequency Data Link Mode 2 (VDL-2). Communication is modeled for essentially all incoming and outgoing nonstop air traffic for just three United States cities: Cleveland, Cincinnati, and Detroit. The simulation involves 111 Air Traffic Control (ATC) ground stations, 32 airports distributed throughout the U.S., which are either sources or destinations for the air traffic landing or departing from the three cities, and also 1,235 equally equipped aircraft taking off, flying realistic free-flight trajectories, and landing in a 24-hr period. Collision-less PCSMA is successfully tested and compared with the traditional CSMA typically associated with VDL- 2. The performance measures include latency, throughput, and packet loss. As expected, PCSMA is much quicker and more efficient than traditional CSMA. These simulation results show the potency of PCSMA for implementing low latency, high throughput and efficient connectivity. Moreover, since PCSMA outperforms traditional CSMA, by simulating with it, we can determine the limits of performance beyond which traditional CSMA may not pass. We are testing a new and better data link that could replace CSMA with relative ease. Work is underway to drastically expand the number of flights to make the simulation more representative of the National Aerospace System.

Selective protein extraction from Chlorobium tepidum chlorosomes using detergents. Evidence that CsmA forms multimers and binds bacteriochlorophyll a.

PubMed

Bryant, Donald A; Vassilieva, Elena V; Frigaard, Niels-Ulrik; Li, Hui

2002-12-03

Chlorosomes of the photosynthetic green sulfur bacterium Chlorobium tepidum consist of bacteriochlorophyll (BChl) c aggregates that are surrounded by a lipid-protein monolayer envelope that contains ten different proteins. Chlorosomes also contain a small amount of BChl a, but the organization and location of this BChl a are not yet clearly understood. Chlorosomes were treated with sodium dodecyl sulfate (SDS), Lubrol PX, or Triton X-100, separately or in combination with 1-hexanol, and the extracted components were separated from the residual chlorosomes by ultrafiltration on centrifugal filters. When chlorosomes were treated with low concentrations of SDS, all proteins except CsmA were extracted. However, this treatment did not significantly alter the size and shape of the chlorosomes, did not extract the BChl a, and caused only minor changes in the absorption spectrum of the chlorosomes. Cross-linking studies with SDS-treated chlorosomes revealed the presence of multimers of the major chlorosome protein, CsmA, up to homooctamers. Extraction of chlorosomes with SDS and 1-hexanol solubilized all ten chlorosome envelope proteins as well as BChl a. Although the size and shape of these extracted chlorosomes did not initially differ significantly from untreated chlorosomes, the extracted chlorosomes gradually disintegrated, and rod-shaped BChl c aggregates were sometimes observed. These results strongly suggest that CsmA binds the BChl a in Chlorobium-type chlorosomes and further indicate that none of the nine other chlorosome envelope proteins are absolutely required for maintaining the shape and integrity of chlorosomes. Quantitative estimates suggest that chlorosomes contain approximately equimolar amounts of CsmA and BChl a and that roughly one-third of the surface of the chlorosome is covered by CsmA.

Dual Purpose Simulation: New Data Link Test and Comparison with VDL-2

NASA Technical Reports Server (NTRS)

Robinson, Daryl C.

2002-01-01

While the results of this paper are similar to those of previous research, in this paper technical difficulties present there are eliminated, producing better results, enabling one to more readily see the benefits of Prioritized CSMA (PCSMA). A new analysis section also helps to generalize this research so that it is not limited to exploration of the new concept of PCSMA. Commercially available network simulation software, OPNET version 7.0, simulations are presented involving an important application of the Aeronautical Telecommunications Network (A TN), Controller Pilot Data Link Communications (CPDLC) over the Very High Frequency Data Link Mode 2 (VDL-2). Communication is modeled for essentially all incoming and outgoing nonstop air traffic for just three United States cities: Cleveland, Cincinnati, and Detroit. The simulation involves 111 Air Traffic Control (ATC) ground stations, 32 airports distributed throughout the U.S., which are either sources or destinations for the air traffic landing or departing from the three cities, and also 1,235 equally equipped aircraft- taking off, flying realistic free- flight trajectories, and landing in a 24-hr period. Collision-less PCSMA is successfully tested and compared with the traditional CSMA typically associated with VDL-2. The performance measures include latency, throughput, and packet loss. As expected, PCSMA is much quicker and more efficient than traditional CSMA. These simulation results show the potency of PC SMA for implementing low latency, high throughput and efficient connectivity. Moreover, since PCSMA out performs traditional CSMA, by simulating with it, we can determine the limits of performance beyond which traditional CSMA may not pass. We are testing a new and better data link that could replace CSMA with relative ease. Work is underway to drastically expand the number of flights to make the simulation more representative of the National Aerospace System.

A Hybrid Lifetime Extended Directional Approach for WBANs

PubMed Central

Li, Changle; Yuan, Xiaoming; Yang, Li; Song, Yueyang

2015-01-01

Wireless Body Area Networks (WBANs) can provide real-time and reliable health monitoring, attributing to the human-centered and sensor interoperability properties. WBANs have become a key component of the ubiquitous eHealth (electronic health) revolution that prospers on the basis of information and communication technologies. The prime consideration in WBAN is how to maximize the network lifetime with battery-powered sensor nodes in energy constraint. Novel solutions in Medium Access Control (MAC) protocols are imperative to satisfy the particular BAN scenario and the need of excellent energy efficiency in healthcare applications. In this paper, we propose a hybrid Lifetime Extended Directional Approach (LEDA) MAC protocol based on IEEE 802.15.6 to reduce energy consumption and prolong network lifetime. The LEDA MAC protocol takes full advantages of directional superiority in energy saving that employs multi-beam directional mode in Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) and single-beam directional mode in Time Division Multiple Access (TDMA) for alternative in data reservation and transmission according to the traffic varieties. Moreover, the impacts of some inherent problems of directional antennas such as deafness and hidden terminal problem can be decreased owing to that all nodes generate individual beam according to user priorities designated. Furthermore, LEDA MAC employs a Dynamic Polled Allocation Period (DPAP) for burst data transmissions to increase the network reliability and adaptability. Extensive analysis and simulation results show that the proposed LEDA MAC protocol achieves extended network lifetime with improved performance compared with IEEE 802.15.6. PMID:26556357

Uncoordinated MAC for Adaptive Multi-Beam Directional Networks: Analysis and Evaluation

DTIC Science & Technology

2016-04-10

transmission times, hence traditional CSMA approaches are not appropriate. We first present our model of these multi-beamforming capa- bilities and the...resulting wireless interference. We then derive an upper bound on multi-access performance for an idealized version of this physical layer. We then present... transmissions and receptions in a mobile ad-hoc network has in practice led to very constrained topologies. As mentioned, one approach for system design is to de

Dual Purpose Simulation: New Data Link Test and Performance Limit Testing of Currently Deployed Data Link

NASA Technical Reports Server (NTRS)

Robinson, Daryl C.

2002-01-01

While the results of this paper are similar to those of [I], in this paper technical difficulties present in [I] are eliminated, producing better results, enabling one to more readily see the benefits of Prioritized CSMA (PCSMA). A new analysis section also helps to generalize this research so that it is not limited to exploration of the new concept of PCSMA. Commercially available network simulation software, OPNET version 7.0, simulations are presented involving an important application of the Aeronautical Telecommunications Network (ATN), Controller Pilot Data Link Communications (CPDLC) over the Very High Frequency Data Link Mode 2 (VDL-2). Communication is modeled for essentially all incoming and outgoing nonstop air-traffic for just three United States cities: Cleveland, Cincinnati, and Detroit. The simulation involves 111 Air Traffic Control (ATC) ground stations, 32 airports distributed throughout the U.S., which are either sources or destinations for the air traffic landing or departing from the three cities, and also 1,235 equally equipped aircraft-taking off, flying realistic free-flight trajectories, and landing in a 24-hr period. Collision-less PCSMA is successfully tested and compared with the traditional CSMA typically associated with VDL-2. The performance measures include latency, throughput, and packet loss. As expected, PCSMA is much quicker and more efficient than traditional CSMA. These simulation results show the potency of PCSMA for implementing low latency, high throughput and efficient connectivity. Moreover, since PCSMA outperforms traditional CSMA, by simulating with it, we can determine the limits of performance beyond which traditional CSMA may not pass. So we have the tools to determine the traffic-loading conditions where traditional CSMA will fail, and we are testing a new and better data link that could replace it with relative ease. Work is currently being done to drastically expand the number of flights to make the simulation more representative of the National Aerospace System.

Modeling and Performance Evaluation of Backoff Misbehaving Nodes in CSMA/CA Networks

DTIC Science & Technology

2012-08-01

Modeling and Performance Evaluation of Backoff Misbehaving Nodes in CSMA/CA Networks Zhuo Lu, Student Member, IEEE, Wenye Wang, Senior Member, IEEE... misbehaving nodes can obtain, we define and study two general classes of backoff misbehavior: continuous misbehavior, which keeps manipulating the backoff...misbehavior sporadically. Our approach is to introduce a new performance metric, namely order gain, to characterize the performance benefits of misbehaving

TERRESTRIAL PLANET FORMATION AROUND THE CIRCUMBINARY HABITABLE ZONE: INWARD MIGRATION IN THE PLANETESIMAL SWARM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong Yanxiang; Zhou Jilin; Xie Jiwei, E-mail: yxgong@nju.edu.cn, E-mail: zhoujl@nju.edu.cn

2013-01-20

According to the core accretion theory, circumbinary embryos can form only beyond a critical semimajor axis (CSMA). However, due to the relatively high density of solid materials in the inner disk, a significant amount of small planetesimals must exist in the inner zone when embryos form outside this CSMA. Thus, embryo migration induced by the planetesimal swarm is possible after gas disk depletion. Through numerical simulations, we found that (1) the scattering-driven inward migration of embryos is robust and planets can form in the habitable zone if we adopt a mass distribution of an MMSN-like disk; (2) the total massmore » of the planetesimals in the inner region and continuous embryo-embryo scattering are two key factors that cause significant embryo migrations; and (3) the scattering-driven migration of embryos is a natural water-delivery mechanism. We propose that planet detections should focus on the close binary with its habitable zone near CSMA.« less

The AAS Working Group on Accessibility and Disability (WGAD): Year 1 Highlights

NASA Astrophysics Data System (ADS)

Aarnio, Alicia; Monkiewicz, Jacqueline; Murphy, Nicholas Arnold; Nordhaus, Jason; Tuttle, Sarah E.

2017-01-01

The AAS Working Group on Accessibility and Disability (WGAD) was formed in January of 2016 with the express purpose of seeking equity of opportunity and building inclusive practices for disabled astronomers at all career stages. In our first year, the WGAD has been actively developing resources and the online infrastructure for the dissemination of information and engagement with the astronomy community. Our official WGAD website has gone live, and we have used both the access: astronomy google group and blog to discuss specific issues of disability justice and to raise awareness for less-discussed barriers to access. The WGAD has developed relationships and collaboration with AAS inclusion committees (SGMA, CSMA, CSWA) so our work can recognize and address the intersections of identity astronomers occupy. In this presentation, we summarize our year one activities, focusing on our recently developed set of recommendations for journal accessibility to ensure everyone can engage with journal content and navigate the submission process. We will also discuss ongoing and future endeavors: a best practices guide for accessibility to be available via our website, and a site visit program.

In Vitro and In Vivo Evaluation of Casein as a Drug Carrier for Enzymatically Triggered Dissolution Enhancement from Solid Dispersions.

PubMed

Bani-Jaber, Ahmad; Alshawabkeh, Iyad; Abdullah, Samaa; Hamdan, Imad; Ardakani, Adel; Habash, Maha

2017-07-01

Due to its unique properties, such as biodegradability, biocompatibility, high amphiphilic property, and micelle formation, casein (CS) has been increasingly studied for drug delivery. We used CS as a drug carrier in solid dispersions (SDs) and evaluated the effect of its degradation by trypsin on drug dissolution from the dispersions. SDs of CS and mefenamic acid (MA) were prepared by physical mixing, kneading, and coprecipitation methods. In comparison to pure MA, the dispersions were evaluated for drug-protein interaction, loss of drug crystalinity, and drug morphology by differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Drug dissolution from the dispersions was evaluated in simulated intestinal fluid as enzyme free and trypsin-enriched media. Furthermore, in vivo drug absorption of MA from CS-MA coprecipitate was evaluated in rats, in comparison with a reference SD of polyethylene glycol and MA (PEG-MA SD). Relative to other CS preparations, CS-MA coprecipitate showed the highest loss of drug crystallinity, drug micronization, and CS-MA interaction. CS remarkably enhanced the dissolution rate and extent of MA from the physical and kneaded mixtures. However, the highest dissolution enhancement was obtained when MA was coprecipitated with CS. Trypsin that can hydrolyze CS during dissolution resulted in further enhancement of MA dissolution from the physical and kneaded mixtures. However, a corresponding retardation effect was obtained for the coprecipitate. In correlation with in vitro drug release, CS-MA coprecipitate also showed significantly higher MA bioavailability in rats than PEG-MA SD.

Spacelab system analysis: The modified free access protocol: An access protocol for communication systems with periodic and Poisson traffic

NASA Technical Reports Server (NTRS)

Ingels, Frank; Owens, John; Daniel, Steven

1989-01-01

The protocol definition and terminal hardware for the modified free access protocol, a communications protocol similar to Ethernet, are developed. A MFA protocol simulator and a CSMA/CD math model are also developed. The protocol is tailored to communication systems where the total traffic may be divided into scheduled traffic and Poisson traffic. The scheduled traffic should occur on a periodic basis but may occur after a given event such as a request for data from a large number of stations. The Poisson traffic will include alarms and other random traffic. The purpose of the protocol is to guarantee that scheduled packets will be delivered without collision. This is required in many control and data collection systems. The protocol uses standard Ethernet hardware and software requiring minimum modifications to an existing system. The modification to the protocol only affects the Ethernet transmission privileges and does not effect the Ethernet receiver.

Access Protocol For An Industrial Optical Fibre LAN

NASA Astrophysics Data System (ADS)

Senior, John M.; Walker, William M.; Ryley, Alan

1987-09-01

A structure for OSI levels 1 and 2 of a local area network suitable for use in a variety of industrial environments is reported. It is intended that the LAN will utilise optical fibre technology at the physical level and a hybrid of dynamically optimisable token passing and CSMA/CD techniques at the data link (IEEE 802 medium access control - logical link control) level. An intelligent token passing algorithm is employed which dynamically allocates tokens according to the known upper limits on the requirements of each device. In addition a system of stochastic tokens is used to increase efficiency when the stochastic traffic is significant. The protocol also allows user-defined priority systems to be employed and is suitable for distributed or centralised implementation. The results of computer simulated performance characteristics for the protocol using a star-ring topology are reported which demonstrate its ability to perform efficiently with the device and traffic loads anticipated within an industrial environment.

Evaluation of the Effects of Hidden Node Problems in IEEE 802.15.7 Uplink Performance

PubMed Central

Ley-Bosch, Carlos; Alonso-González, Itziar; Sánchez-Rodríguez, David; Ramírez-Casañas, Carlos

2016-01-01

In the last few years, the increasing use of LEDs in illumination systems has been conducted due to the emergence of Visible Light Communication (VLC) technologies, in which data communication is performed by transmitting through the visible band of the electromagnetic spectrum. In 2011, the Institute of Electrical and Electronics Engineers (IEEE) published the IEEE 802.15.7 standard for Wireless Personal Area Networks based on VLC. Due to limitations in the coverage of the transmitted signal, wireless networks can suffer from the hidden node problems, when there are nodes in the network whose transmissions are not detected by other nodes. This problem can cause an important degradation in communications when they are made by means of the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) access control method, which is used in IEEE 802.15.7 This research work evaluates the effects of the hidden node problem in the performance of the IEEE 802.15.7 standard We implement a simulator and analyze VLC performance in terms of parameters like end-to-end goodput and message loss rate. As part of this research work, a solution to the hidden node problem is proposed, based on the use of idle patterns defined in the standard. Idle patterns are sent by the network coordinator node to communicate to the other nodes that there is an ongoing transmission. The validity of the proposed solution is demonstrated with simulation results. PMID:26861352

Evaluation of the Effects of Hidden Node Problems in IEEE 802.15.7 Uplink Performance.

PubMed

Ley-Bosch, Carlos; Alonso-González, Itziar; Sánchez-Rodríguez, David; Ramírez-Casañas, Carlos

2016-02-06

In the last few years, the increasing use of LEDs in illumination systems has been conducted due to the emergence of Visible Light Communication (VLC) technologies, in which data communication is performed by transmitting through the visible band of the electromagnetic spectrum. In 2011, the Institute of Electrical and Electronics Engineers (IEEE) published the IEEE 802.15.7 standard for Wireless Personal Area Networks based on VLC. Due to limitations in the coverage of the transmitted signal, wireless networks can suffer from the hidden node problems, when there are nodes in the network whose transmissions are not detected by other nodes. This problem can cause an important degradation in communications when they are made by means of the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) access control method, which is used in IEEE 802.15.7 This research work evaluates the effects of the hidden node problem in the performance of the IEEE 802.15.7 standard We implement a simulator and analyze VLC performance in terms of parameters like end-to-end goodput and message loss rate. As part of this research work, a solution to the hidden node problem is proposed, based on the use of idle patterns defined in the standard. Idle patterns are sent by the network coordinator node to communicate to the other nodes that there is an ongoing transmission. The validity of the proposed solution is demonstrated with simulation results.

An Ultra-Low Power and Flexible Acoustic Modem Design to Develop Energy-Efficient Underwater Sensor Networks

PubMed Central

Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

2012-01-01

This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network. PMID:22969324

An ultra-low power and flexible acoustic modem design to develop energy-efficient underwater sensor networks.

PubMed

Sánchez, Antonio; Blanc, Sara; Yuste, Pedro; Perles, Angel; Serrano, Juan José

2012-01-01

This paper is focused on the description of the physical layer of a new acoustic modem called ITACA. The modem architecture includes as a major novelty an ultra-low power asynchronous wake-up system implementation for underwater acoustic transmission that is based on a low-cost off-the-shelf RFID peripheral integrated circuit. This feature enables a reduced power dissipation of 10 μW in stand-by mode and registers very low power values during reception and transmission. The modem also incorporates clear channel assessment (CCA) to support CSMA-based medium access control (MAC) layer protocols. The design is part of a compact platform for a long-life short/medium range underwater wireless sensor network.

Oregon's Toxic Household Products Law.

PubMed

Neumann, C M; Giffin, S; Hall, R; Henderson, M; Buhler, D R

2000-01-01

In 1991, Oregon became the first state in the U.S. to require the addition of an aversive agent to ethylene glycol-containing antifreeze and methanol-containing windshield wiper fluid. This new law, entitled "Toxic Household Products (THP) Act," was designed to reduce pediatric and animal poisonings from accidental ingestion of these two potentially lethal consumer automotive products. While not the stated intention of the law, addition of aversive agents to consumer automotive products could also reduce adult poisonings associated with intentional (suicides or alcoholics ingesting methanol-containing windshield wiper fluid) or accidental exposures. This law went into effect April 30, 1995, following settlement of a lawsuit brought by the Chemical Manufacturing Specialties Association (CSMA), a trade group representing the five largest manufacturers of ethylene glycol-based antifreeze in the U.S. This paper discusses the major policy issues that arose following the passage of Oregon's THP Act. Major provisions of the law are provided along with a discussion of CSMA's opposition to the Act's implementation. A description of the eventual settlement that was reached with CSMA as well as the major components of Oregon Health Division's (OHD) enforcement program are also highlighted. Data are presented for 1987 through 1998 on the number of exposures and severity of effects for pediatric cases (children < 6 years old) following exposure to both of these potentially lethal automotive products. However, because of the low incidence of exposures each year, these data are insufficient to draw any conclusions on the impact of the THP Act.

Collision Resolution Scheme with Offset for Improved Performance of Heterogeneous WLAN

NASA Astrophysics Data System (ADS)

Upadhyay, Raksha; Vyavahare, Prakash D.; Tokekar, Sanjiv

2016-03-01

CSMA/CA based DCF of 802.11 MAC layer employs best effort delivery model, in which all stations compete for channel access with same priority. Heterogeneous conditions result in unfairness among stations and degradation in throughput, therefore, providing different priorities to different applications for required quality of service in heterogeneous networks is challenging task. This paper proposes a collision resolution scheme with a novel concept of introducing offset, which is suitable for heterogeneous networks. Selection of random value by a station for its contention with offset results in reduced probability of collision. Expression for the optimum value of the offset is also derived. Results show that proposed scheme, when applied to heterogeneous networks, has improved throughput and fairness than conventional scheme. Results show that proposed scheme also exhibits higher throughput and fairness with reduced delay in homogeneous networks.

Optimizing the MAC Protocol in Localization Systems Based on IEEE 802.15.4 Networks

PubMed Central

Claver, Jose M.; Ezpeleta, Santiago

2017-01-01

Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, the wireless transceivers integrated in the network motes are usually based on the IEEE 802.15.4 standard. But, the CSMA-CA, which is the basis for the medium access protocols in this category of communication systems, is not suitable when several users want to exchange bursts of radio packets with the same beacon to acquire the radio signal strength indicator (RSSI) values needed in the location process. Therefore, new protocols are necessary to avoid the packet collisions that appear when multiple users try to communicate with the same beacons. On the other hand, the RSSI sampling process should be carried out very quickly because some systems cannot tolerate a large delay in the location process. This is even more important when the RSSI sampling process includes measures with different signal power levels or frequency channels. The principal objective of this work is to speed up the RSSI sampling process in indoor localization systems. To achieve this objective, the main contribution is the proposal of a new MAC protocol that eliminates the medium access contention periods and decreases the number of packet collisions to accelerate the RSSI collection process. Moreover, the protocol increases the overall network throughput taking advantage of the frequency channel diversity. The presented results show the suitability of this protocol for reducing the RSSI gathering delay and increasing the network throughput in simulated and real environments. PMID:28684666

Optimizing the MAC Protocol in Localization Systems Based on IEEE 802.15.4 Networks.

PubMed

Pérez-Solano, Juan J; Claver, Jose M; Ezpeleta, Santiago

2017-07-06

Radio frequency signals are commonly used in the development of indoor localization systems. The infrastructure of these systems includes some beacons placed at known positions that exchange radio packets with users to be located. When the system is implemented using wireless sensor networks, the wireless transceivers integrated in the network motes are usually based on the IEEE 802.15.4 standard. But, the CSMA-CA, which is the basis for the medium access protocols in this category of communication systems, is not suitable when several users want to exchange bursts of radio packets with the same beacon to acquire the radio signal strength indicator (RSSI) values needed in the location process. Therefore, new protocols are necessary to avoid the packet collisions that appear when multiple users try to communicate with the same beacons. On the other hand, the RSSI sampling process should be carried out very quickly because some systems cannot tolerate a large delay in the location process. This is even more important when the RSSI sampling process includes measures with different signal power levels or frequency channels. The principal objective of this work is to speed up the RSSI sampling process in indoor localization systems. To achieve this objective, the main contribution is the proposal of a new MAC protocol that eliminates the medium access contention periods and decreases the number of packet collisions to accelerate the RSSI collection process. Moreover, the protocol increases the overall network throughput taking advantage of the frequency channel diversity. The presented results show the suitability of this protocol for reducing the RSSI gathering delay and increasing the network throughput in simulated and real environments.

A comparative study of software programmes for cross-sectional skeletal muscle and adipose tissue measurements on abdominal computed tomography scans of rectal cancer patients.

PubMed

van Vugt, Jeroen L A; Levolger, Stef; Gharbharan, Arvind; Koek, Marcel; Niessen, Wiro J; Burger, Jacobus W A; Willemsen, Sten P; de Bruin, Ron W F; IJzermans, Jan N M

2017-04-01

The association between body composition (e.g. sarcopenia or visceral obesity) and treatment outcomes, such as survival, using single-slice computed tomography (CT)-based measurements has recently been studied in various patient groups. These studies have been conducted with different software programmes, each with their specific characteristics, of which the inter-observer, intra-observer, and inter-software correlation are unknown. Therefore, a comparative study was performed. Fifty abdominal CT scans were randomly selected from 50 different patients and independently assessed by two observers. Cross-sectional muscle area (CSMA, i.e. rectus abdominis, oblique and transverse abdominal muscles, paraspinal muscles, and the psoas muscle), visceral adipose tissue area (VAT), and subcutaneous adipose tissue area (SAT) were segmented by using standard Hounsfield unit ranges and computed for regions of interest. The inter-software, intra-observer, and inter-observer agreement for CSMA, VAT, and SAT measurements using FatSeg, OsiriX, ImageJ, and sliceOmatic were calculated using intra-class correlation coefficients (ICCs) and Bland-Altman analyses. Cohen's κ was calculated for the agreement of sarcopenia and visceral obesity assessment. The Jaccard similarity coefficient was used to compare the similarity and diversity of measurements. Bland-Altman analyses and ICC indicated that the CSMA, VAT, and SAT measurements between the different software programmes were highly comparable (ICC 0.979-1.000, P < 0.001). All programmes adequately distinguished between the presence or absence of sarcopenia (κ = 0.88-0.96 for one observer and all κ = 1.00 for all comparisons of the other observer) and visceral obesity (all κ = 1.00). Furthermore, excellent intra-observer (ICC 0.999-1.000, P < 0.001) and inter-observer (ICC 0.998-0.999, P < 0.001) agreement for all software programmes were found. Accordingly, excellent Jaccard similarity coefficients were found for all comparisons (mean ≥ 0.964). FatSeg, OsiriX, ImageJ, and sliceOmatic showed an excellent agreement for CSMA, VAT, and SAT measurements on abdominal CT scans. Furthermore, excellent inter-observer and intra-observer agreement were achieved. Therefore, results of studies using these different software programmes can reliably be compared. © 2016 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

A comparative study of software programmes for cross‐sectional skeletal muscle and adipose tissue measurements on abdominal computed tomography scans of rectal cancer patients

PubMed Central

Levolger, Stef; Gharbharan, Arvind; Koek, Marcel; Niessen, Wiro J.; Burger, Jacobus W.A.; Willemsen, Sten P.; de Bruin, Ron W.F.

2016-01-01

Abstract Background The association between body composition (e.g. sarcopenia or visceral obesity) and treatment outcomes, such as survival, using single‐slice computed tomography (CT)‐based measurements has recently been studied in various patient groups. These studies have been conducted with different software programmes, each with their specific characteristics, of which the inter‐observer, intra‐observer, and inter‐software correlation are unknown. Therefore, a comparative study was performed. Methods Fifty abdominal CT scans were randomly selected from 50 different patients and independently assessed by two observers. Cross‐sectional muscle area (CSMA, i.e. rectus abdominis, oblique and transverse abdominal muscles, paraspinal muscles, and the psoas muscle), visceral adipose tissue area (VAT), and subcutaneous adipose tissue area (SAT) were segmented by using standard Hounsfield unit ranges and computed for regions of interest. The inter‐software, intra‐observer, and inter‐observer agreement for CSMA, VAT, and SAT measurements using FatSeg, OsiriX, ImageJ, and sliceOmatic were calculated using intra‐class correlation coefficients (ICCs) and Bland–Altman analyses. Cohen's κ was calculated for the agreement of sarcopenia and visceral obesity assessment. The Jaccard similarity coefficient was used to compare the similarity and diversity of measurements. Results Bland–Altman analyses and ICC indicated that the CSMA, VAT, and SAT measurements between the different software programmes were highly comparable (ICC 0.979–1.000, P < 0.001). All programmes adequately distinguished between the presence or absence of sarcopenia (κ = 0.88–0.96 for one observer and all κ = 1.00 for all comparisons of the other observer) and visceral obesity (all κ = 1.00). Furthermore, excellent intra‐observer (ICC 0.999–1.000, P < 0.001) and inter‐observer (ICC 0.998–0.999, P < 0.001) agreement for all software programmes were found. Accordingly, excellent Jaccard similarity coefficients were found for all comparisons (mean ≥ 0.964). Conclusions FatSeg, OsiriX, ImageJ, and sliceOmatic showed an excellent agreement for CSMA, VAT, and SAT measurements on abdominal CT scans. Furthermore, excellent inter‐observer and intra‐observer agreement were achieved. Therefore, results of studies using these different software programmes can reliably be compared. PMID:27897414

On the routing protocol influence on the resilience of wireless sensor networks to jamming attacks.

PubMed

Del-Valle-Soto, Carolina; Mex-Perera, Carlos; Monroy, Raul; Nolazco-Flores, Juan Arturo

2015-03-27

In this work, we compare a recently proposed routing protocol, the multi-parent hierarchical (MPH) protocol, with two well-known protocols, the ad hoc on-demand distance vector (AODV) and dynamic source routing (DSR). For this purpose, we have developed a simulator, which faithfully reifies the workings of a given protocol, considering a fixed, reconfigurable ad hoc network given by the number and location of participants, and general network conditions. We consider a scenario that can be found in a large number of wireless sensor network applications, a single sink node that collects all of the information generated by the sensors. The metrics used to compare the protocols were the number of packet retransmissions, carrier sense multiple access (CSMA) inner loop retries, the number of nodes answering the queries from the coordinator (sink) node and the energy consumption. We tested the network under ordinary (without attacks) conditions (and combinations thereof) and when it is subject to different types of jamming attacks (in particular, random and reactive jamming attacks), considering several positions for the jammer. Our results report that MPH has a greater ability to tolerate such attacks than DSR and AODV, since it minimizes and encapsulates the network segment under attack. The self-configuring capabilities of MPH derived from a combination of a proactive routes update, on a periodic-time basis, and a reactive behavior provide higher resilience while offering a better performance (overhead and energy consumption) than AODV and DSR, as shown in our simulation results.

A secure RFID-based WBAN for healthcare applications.

PubMed

Ullah, Sana; Alamri, Atif

2013-10-01

A Wireless Body Area Network (WBAN) allows the seamless integration of small and intelligent invasive or non-invasive sensor nodes in, on or around a human body for continuous health monitoring. These nodes are expected to use different power-efficient protocols in order to extend the WBAN lifetime. This paper highlights the power consumption and security issues of WBAN for healthcare applications. Numerous power saving mechanisms are discussed and a secure RFID-based protocol for WBAN is proposed. The performance of the proposed protocol is analyzed and compared with that of IEEE 802.15.6-based CSMA/CA and preamble-based TDMA protocols using extensive simulations. It is shown that the proposed protocol is power-efficient and protects patients' data from adversaries. It is less vulnerable to different attacks compared to that of IEEE 802.15.6-based CSMA/CA and preamble-based TDMA protocols. For a low traffic load and a single alkaline battery of capacity 2.6 Ah, the proposed protocol could extend the WBAN lifetime, when deployed on patients in hospitals or at homes, to approximately five years.

Self-assembled poly(ε-caprolactone)-g-chondroitin sulfate copolymers as an intracellular doxorubicin delivery carrier against lung cancer cells

PubMed Central

Lin, Yue-Jin; Liu, Yu-Sheng; Yeh, Hsin-Hwa; Cheng, Tian-Lu; Wang, Li-Fang

2012-01-01

The aim of this study was to utilize self-assembled polycaprolactone (PCL)-grafted chondroitin sulfate (CS) as an anticancer drug carrier. We separately introduced double bonds to the hydrophobic PCL and the hydrophilic CS. The modified PCL was reacted with the modified CS through a radical reaction (CSMA-g-PCL). The copolymer without doxorubicin (DOX) was noncytotoxic in CRL-5802 and NCI-H358 cells at a concentration ranging from 5–1000 μg/mL and DOX-loaded CSMA-g-PCL (Micelle DOX) had the lowest inhibitory concentration of 50% cell growth values against the NCI-H358 cells among test samples. The cellular uptake of Micelle DOX into the cells was confirmed by flow cytometric data and confocal laser scanning microscopic images. The in vivo tumor-targeting efficacy of Micelle DOX was realized using an NCI-H358 xenograft nude mouse model. The mice administered with Micelle DOX showed suppressed growth of the NCI-H358 lung tumor compared with those administered with phosphate-buffered saline and free DOX. PMID:22904627

A Green Media Access Method for IEEE 802.15.6 Wireless Body Area Network.

PubMed

Jacob, Anil K; Jacob, Lillykutty

2017-09-30

It is of utmost importance to conserve battery energy to the maximum possible extent in WBAN nodes while collecting and transferring medical data. The IEEE 802.15.6 WBAN standard does not specify any method to conserve energy. This paper focuses on a method to conserve energy in IEEE 802.15.6 WBAN nodes when using CSMA/CA, while simultaneously restricting data delivery delay to the required value as specified in medical applications. The technique is to allow the nodes to sleep all the times except for receiving beacons and for transmitting data frames whenever a data frame enters an empty buffer. The energy consumed by the nodes and the average latency of data frame for periodical arrival of data are found out analytically. The analytical results are validated and also the proposed method is compared with other energy conserving schemes, using Castalia simulation studies. The proposed method shows superior performance in both device lifetime and latency of emergency medical data.

Deletion of a Chitin Synthase Gene in a Citric Acid Producing Strain of Aspergillus niger

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rinker, Torri E.; Baker, Scott E.

Citric acid production by the filamentous fungus Aspergillus niger is carried out in a process that causes the organism to drastically alter its morphology. This altered morphology includes hyphal swelling and highly limited polar growth resulting in clumps of swollen cells that eventually aggregate into pellets of approximately 100 microns in diameter. In this pelleted form, A. niger has increased citric acid production as compared to growth in filamentous form. Chitin is a crucial component of the cell wall of filamentous fungi. Alterations in the deposition or production of chitin may have profound effects on the morphology of the organism.more » In order to study the role of chitin synthesis in pellet formation we have deleted a chitin synthase gene (csmA) in Aspergillus niger strain ATCC 11414 using a PCR based deletion construct. This class of chitin synthases is only found in filamentous fungi and is not present in yeasts. The csmA genes contain a myosin motor domain at the N-terminus and a chitin synthesis domain at the C-terminus. They are believed to contribute to the specialized polar growth observed in filamentous fungi that is lacking in yeasts. The csmA deletion strain (csmAΔ) was subjected to minimal media with and without osmotic stabilizers as well as tested in citric acid production media. Without osmotic stabilizers, the mutant germlings were abnormally swollen, primarily in the subapical regions, and contained large vacuoles. However, this swelling is ultimately not inhibitory to growth as the germlings are able to recover and undergo polar growth. Colony formation was largely unaffected in the absence of osmotic stabilizers. In citric acid production media csmAΔ was observed to have a 2.5 fold increase in citric acid production. The controlled expression of this class of chitin synthases may be useful for improving production of organic acids in filamentous fungi.« less

Dynamic Spectrum Management for Military Wireless Networks

DTIC Science & Technology

2010-09-01

auctions, and protocols and etiquettes . Command and control assignments are provided by the regulatory agency by reviewing specific licensing...devices and amateur licensees do not have specific frequency assignments. The Protocols and Etiquettes methods allow these devices to operate within a...with Collision Avoidance (CSMA/CA) a protocol . Etiquettes are rules that are followed without explicit interaction between devices. Simple etiquettes

Associations of muscle force, power, cross-sectional muscle area and bone geometry in older UK men.

PubMed

Zengin, Ayse; Pye, Stephen R; Cook, Michael J; Adams, Judith E; Rawer, Rainer; Wu, Frederick C W; O'Neill, Terence W; Ward, Kate A

2017-08-01

Ageing is associated with sarcopenia, osteoporosis, and increased fall risk, all of which contribute to increased fracture risk. Mechanically, bone strength adapts in response to forces created by muscle contractions. Adaptations can be through changes in bone size, geometry, and bending strength. Muscle mass is often used as a surrogate for muscle force; however, force can be increased without changes in muscle mass. Increased fall risk with ageing has been associated with a decline in muscle power-which is a measure of mobility. The aims of this study were as follows: (i) to investigate the relationship between muscle parameters in the upper and lower limbs with age in UK men and the influence of ethnicity on these relationships; (ii) to examine the relationships between jump force/grip strength/cross-sectional muscle area (CSMA) with bone outcomes at the radius and tibia. White European, Black Afro-Caribbean, and South Asian men aged 40-79 years were recruited from Manchester, UK. Cortical bone mineral content, cross-sectional area, cortical area, cross-sectional moment of inertia, and CSMA were measured at the diaphysis of the radius and tibia using peripheral quantitative computed tomography. Lower limb jump force and power were measured from a single two-legged jump performed on a ground-reaction force platform. Grip strength was measured using a dynamometer. Associations between muscle and bone outcomes was determined using linear regression with adjustments for age, height, weight, and ethnicity. Three hundred and one men were recruited. Jump force was negatively associated with age; for every 10 year increase in age, there was a 4% reduction in jump force (P < 0.0001). There was a significant age-ethnicity interaction for jump power (P = 0.039); after adjustments, this was attenuated (P = 0.088). For every 10 year increase in age, grip strength decreased by 11%. Jump force was positively associated with tibial bone outcomes: a 1 standard deviation greater jump force was associated with significantly higher cortical bone mineral content 3.1%, cross-sectional area 4.2%, cortical area 3.4%, and cross-sectional moment of inertia 6.8% (all P < 0.001). Cross-sectional muscle area of the lower leg was not associated with tibial bone outcomes. Both grip strength and CSMA of the arm were positively associated, to a similar extent, with radius diaphyseal bone outcomes. Jump force and power are negatively associated with age in UK men. In the lower limb, the measurement of jump force is more strongly related to bone outcomes than CSMA. It is important to consider jump force and power when understanding the aetiology of bone loss and mobility in ageing men. © 2017 The Authors. Journal of Cachexia, Sarcopenia and Muscle published by John Wiley & Sons Ltd on behalf of the Society on Sarcopenia, Cachexia and Wasting Disorders.

Protocol for buffer space negotiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nessett, D.

There are at least two ways to manage the buffer memory of a communications node. On etechnique veiws the buffer as a single resource that is to be reserved and released as a unit for a particular communication transaction. A more common approach treats the node's buffer space as a collection of resources (e.g., bytes, words, packet slots) capable of being allocated among multiple concurrent conversations. To achieve buffer space multiplexing, some sort of negotiation for buffer space must take place between source and sink nodes before a transaction can commence. Results are presented which indicate that, for an applicationmore » involving a CSMA broadcast network, buffer space multiplexing offers better performance than buffer reservation. To achieve this improvement, a simple protocol is presented that features flow-control information traveling both from source to sink as well as from sink to source. It is argued that this bidirectionality allows the sink to allocate buffer space among its active communication paths more effectively. 13 figures.« less

GLOBECOM '87 - Global Telecommunications Conference, Tokyo, Japan, Nov. 15-18, 1987, Conference Record. Volumes 1, 2, & 3

NASA Astrophysics Data System (ADS)

The present conference on global telecommunications discusses topics in the fields of Integrated Services Digital Network (ISDN) technology field trial planning and results to date, motion video coding, ISDN networking, future network communications security, flexible and intelligent voice/data networks, Asian and Pacific lightwave and radio systems, subscriber radio systems, the performance of distributed systems, signal processing theory, satellite communications modulation and coding, and terminals for the handicapped. Also discussed are knowledge-based technologies for communications systems, future satellite transmissions, high quality image services, novel digital signal processors, broadband network access interface, traffic engineering for ISDN design and planning, telecommunications software, coherent optical communications, multimedia terminal systems, advanced speed coding, portable and mobile radio communications, multi-Gbit/second lightwave transmission systems, enhanced capability digital terminals, communications network reliability, advanced antimultipath fading techniques, undersea lightwave transmission, image coding, modulation and synchronization, adaptive signal processing, integrated optical devices, VLSI technologies for ISDN, field performance of packet switching, CSMA protocols, optical transport system architectures for broadband ISDN, mobile satellite communications, indoor wireless communication, echo cancellation in communications, and distributed network algorithms.

Wireless Sensor Networks for High Fidelity Sampling

DTIC Science & Technology

2007-07-20

Transmission Schedule . . . . . . . . . . 156 8.3 CSMA versus TDMA . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 8.4 Practical Issues...goes into sleep mode when no job is running. Let W be the wakeup time; then the peak at 0 moves to W . In fact the entire graph can be moved to the left...tio n Immediate Context Switching Wakeup from Sleep Context Switching after Finishing Atomic Section Figure 2.9. Histogram of Jitter at 5kHz Sampling

Chitin Synthases with a Myosin Motor-Like Domain Control the Resistance of Aspergillus fumigatus to Echinocandins

PubMed Central

Jiménez-Ortigosa, Cristina; Aimanianda, Vishukumar; Muszkieta, Laetitia; Mouyna, Isabelle; Alsteens, David; Pire, Stéphane; Beau, Remi; Krappmann, Sven; Beauvais, Anne; Dufrêne, Yves F.

2012-01-01

Aspergillus fumigatus has two chitin synthases (CSMA and CSMB) with a myosin motor-like domain (MMD) arranged in a head-to-head configuration. To understand the function of these chitin synthases, single and double csm mutant strains were constructed and analyzed. Although there was a slight reduction in mycelial growth of the mutants, the total chitin synthase activity and the cell wall chitin content were similar in the mycelium of all of the mutants and the parental strain. In the conidia, chitin content in the ΔcsmA strain cell wall was less than half the amount found in the parental strain. In contrast, the ΔcsmB mutant strain and, unexpectedly, the ΔcsmA/ΔcsmB mutant strain did not show any modification of chitin content in their conidial cell walls. In contrast to the hydrophobic conidia of the parental strain, conidia of all of the csm mutants were hydrophilic due to the presence of an amorphous material covering the hydrophobic surface-rodlet layer. The deletion of CSM genes also resulted in an increased susceptibility of resting and germinating conidia to echinocandins. These results show that the deletion of the CSMA and CSMB genes induced a significant disorganization of the cell wall structure, even though they contribute only weakly to the overall cell wall chitin synthesis. PMID:22964252

VoIPNET: A Software Based Communications Tool for Low-Bandwidth Networks

DTIC Science & Technology

2007-06-01

Plan Suplemental Tools. <http://www.dir.state.tx.us/pubs/framework/gate2/riskplan/ Deitel , H.M. and Deitel , P.J. Java: How To Program . 5th...Up. 3rd Edition. California: McGraw-Hill, 2003. Deitel , H.M. and Deitel , P.J. C++: How to Program . 5th Edition. New Jersey: Prentice Hall...users. It is possible for a single user to consume all available bandwidth. Hop limits are programmed during EPLRS 8 network planning. CSMA

Analyzing the effect of routing protocols on media access control protocols in radio networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, C. L.; Drozda, M.; Marathe, A.

2002-01-01

We study the effect of routing protocols on the performance of media access control (MAC) protocols in wireless radio networks. Three well known MAC protocols: 802.11, CSMA, and MACA are considered. Similarly three recently proposed routing protocols: AODV, DSR and LAR scheme 1 are considered. The experimental analysis was carried out using GloMoSim: a tool for simulating wireless networks. The main focus of our experiments was to study how the routing protocols affect the performance of the MAC protocols when the underlying network and traffic parameters are varied. The performance of the protocols was measured w.r.t. five important parameters: (i)more » number of received packets, (ii) average latency of each packet, (iii) throughput (iv) long term fairness and (v) number of control packets at the MAC layer level. Our results show that combinations of routing and MAC protocols yield varying performance under varying network topology and traffic situations. The result has an important implication; no combination of routing protocol and MAC protocol is the best over all situations. Also, the performance analysis of protocols at a given level in the protocol stack needs to be studied not locally in isolation but as a part of the complete protocol stack. A novel aspect of our work is the use of statistical technique, ANOVA (Analysis of Variance) to characterize the effect of routing protocols on MAC protocols. This technique is of independent interest and can be utilized in several other simulation and empirical studies.« less

Aspergillus fumigatus Trehalose-Regulatory Subunit Homolog Moonlights To Mediate Cell Wall Homeostasis through Modulation of Chitin Synthase Activity.

PubMed

Thammahong, Arsa; Caffrey-Card, Alayna K; Dhingra, Sourabh; Obar, Joshua J; Cramer, Robert A

2017-04-25

Trehalose biosynthesis is found in fungi but not humans. Proteins involved in trehalose biosynthesis are essential for fungal pathogen virulence in humans and plants through multiple mechanisms. Loss of canonical trehalose biosynthesis genes in the human pathogen Aspergillus fumigatus significantly alters cell wall structure and integrity, though the mechanistic link between these virulence-associated pathways remains enigmatic. Here we characterize genes, called tslA and tslB , which encode proteins that contain domains similar to those corresponding to trehalose-6-phosphate phosphatase but lack critical catalytic residues for phosphatase activity. Loss of tslA reduces trehalose content in both conidia and mycelia, impairs cell wall integrity, and significantly alters cell wall structure. To gain mechanistic insights into the role that TslA plays in cell wall homeostasis, immunoprecipitation assays coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to reveal a direct interaction between TslA and CsmA, a type V chitin synthase enzyme. TslA regulates not only chitin synthase activity but also CsmA sub-cellular localization. Loss of TslA impacts the immunopathogenesis of murine invasive pulmonary aspergillosis through altering cytokine production and immune cell recruitment. In conclusion, our data provide a novel model whereby proteins in the trehalose pathway play a direct role in fungal cell wall homeostasis and consequently impact fungus-host interactions. IMPORTANCE Human fungal infections are increasing globally due to HIV infections and increased use of immunosuppressive therapies for many diseases. Therefore, new antifungal drugs with reduced side effects and increased efficacy are needed to improve treatment outcomes. Trehalose biosynthesis exists in pathogenic fungi and is absent in humans. Components of the trehalose biosynthesis pathway are important for the virulence of human-pathogenic fungi, including Aspergillus fumigatus Consequently, it has been proposed that components of this pathway are potential targets for antifungal drug development. However, how trehalose biosynthesis influences the fungus-host interaction remains enigmatic. One phenotype associated with fungal trehalose biosynthesis mutants that remains enigmatic is cell wall perturbation. Here we discovered a novel moonlighting role for a regulatory-like subunit of the trehalose biosynthesis pathway in A. fumigatus that regulates cell wall homeostasis through modulation of chitin synthase localization and activity. As the cell wall is a current and promising therapeutic target for fungal infections, understanding the role of trehalose biosynthesis in cell wall homeostasis and virulence is expected to help define new therapeutic opportunities. Copyright © 2017 Thammahong et al.

Correlates of bone quality in older persons

PubMed Central

Lauretani, F.; Bandinelli, S.; Russo, C.R.; Maggio, M.; Di Iorio, A.; Cherubini, A.; Maggio, D.; Ceda, G.P.; Valenti, G.; Guralnik, J.M.; Ferrucci, L.

2009-01-01

Purpose of the study In a population-based sample of older persons, we studied the relationship between tibial bone density and geometry and factors potentially affecting osteoporosis. Methods Of the 1260 participants aged 65 years or older eligible for the InCHIANTI study, 1155 received an interview and 915 (79.2%) had complete data on tibial QCTscans and other variables used in the analysis presented here. The final study population included 807 persons (372 men and 435 women, age range 65–96 years) after exclusion of participants affected by bone diseases or treated with drugs that interfere with bone metabolism. Results In both sexes, calf cross-sectional muscle area (CSMA) was significantly and independently associated with total bone cross-sectional area (tCSA) and cortical bone cross-sectional area (cCSA) but not with trabecular or cortical volumetric bone mineral density (vBMD). Bioavailable testosterone (Bio-T) was independently associated with both trabecular and cortical vBMD in both sexes. In women, independently of confounders, 25(OH)-vitamin D was positively associated with tCSA and cortical vBMD, while PTH was negatively associated with cortical vBMD. IL-1 beta was negatively correlated with cortical vBMD in women, while TNF-alpha was associated with enhanced bone geometrical adaptation in men. Conclusions Physiological parameters that are generically considered risk factors for osteoporosis were associated with specific bone parameters assessed by tibial QCT. Factors known to be associated with increased bone reabsorption, such as 25(OH)-vitamin D, PTH and Bio-T, affected mainly volumetric BMD, while factors associated with bone mechanical stimulation, such as CSMA, affected primarily bone geometry. Our results also suggested that pro-inflammatory cytokines might be considered as markers of bone resorption. PMID:16709469

A Distributed Transmission Rate Adjustment Algorithm in Heterogeneous CSMA/CA Networks

PubMed Central

Xie, Shuanglong; Low, Kay Soon; Gunawan, Erry

2015-01-01

Distributed transmission rate tuning is important for a wide variety of IEEE 802.15.4 network applications such as industrial network control systems. Such systems often require each node to sustain certain throughput demand in order to guarantee the system performance. It is thus essential to determine a proper transmission rate that can meet the application requirement and compensate for network imperfections (e.g., packet loss). Such a tuning in a heterogeneous network is difficult due to the lack of modeling techniques that can deal with the heterogeneity of the network as well as the network traffic changes. In this paper, a distributed transmission rate tuning algorithm in a heterogeneous IEEE 802.15.4 CSMA/CA network is proposed. Each node uses the results of clear channel assessment (CCA) to estimate the busy channel probability. Then a mathematical framework is developed to estimate the on-going heterogeneous traffics using the busy channel probability at runtime. Finally a distributed algorithm is derived to tune the transmission rate of each node to accurately meet the throughput requirement. The algorithm does not require modifications on IEEE 802.15.4 MAC layer and it has been experimentally implemented and extensively tested using TelosB nodes with the TinyOS protocol stack. The results reveal that the algorithm is accurate and can satisfy the throughput demand. Compared with existing techniques, the algorithm is fully distributed and thus does not require any central coordination. With this property, it is able to adapt to traffic changes and re-adjust the transmission rate to the desired level, which cannot be achieved using the traditional modeling techniques. PMID:25822140

Wireless Networks under a Backoff Attack: A Game Theoretical Perspective.

PubMed

Parras, Juan; Zazo, Santiago

2018-01-30

We study a wireless sensor network using CSMA/CA in the MAC layer under a backoff attack: some of the sensors of the network are malicious and deviate from the defined contention mechanism. We use Bianchi's network model to study the impact of the malicious sensors on the total network throughput, showing that it causes the throughput to be unfairly distributed among sensors. We model this conflict using game theory tools, where each sensor is a player. We obtain analytical solutions and propose an algorithm, based on Regret Matching, to learn the equilibrium of the game with an arbitrary number of players. Our approach is validated via simulations, showing that our theoretical predictions adjust to reality.

Wireless Networks under a Backoff Attack: A Game Theoretical Perspective

PubMed Central

Zazo, Santiago

2018-01-01

We study a wireless sensor network using CSMA/CA in the MAC layer under a backoff attack: some of the sensors of the network are malicious and deviate from the defined contention mechanism. We use Bianchi’s network model to study the impact of the malicious sensors on the total network throughput, showing that it causes the throughput to be unfairly distributed among sensors. We model this conflict using game theory tools, where each sensor is a player. We obtain analytical solutions and propose an algorithm, based on Regret Matching, to learn the equilibrium of the game with an arbitrary number of players. Our approach is validated via simulations, showing that our theoretical predictions adjust to reality. PMID:29385752

Throughput and delay analysis of IEEE 802.15.6-based CSMA/CA protocol.

PubMed

Ullah, Sana; Chen, Min; Kwak, Kyung Sup

2012-12-01

The IEEE 802.15.6 is a new communication standard on Wireless Body Area Network (WBAN) that focuses on a variety of medical, Consumer Electronics (CE) and entertainment applications. In this paper, the throughput and delay performance of the IEEE 802.15.6 is presented. Numerical formulas are derived to determine the maximum throughput and minimum delay limits of the IEEE 802.15.6 for an ideal channel with no transmission errors. These limits are derived for different frequency bands and data rates. Our analysis is validated by extensive simulations using a custom C+ + simulator. Based on analytical and simulation results, useful conclusions are derived for network provisioning and packet size optimization for different applications.

Proceedings of the Mobile Satellite System Architectures and Multiple Access Techniques Workshop

NASA Technical Reports Server (NTRS)

Dessouky, Khaled

1989-01-01

The Mobile Satellite System Architectures and Multiple Access Techniques Workshop served as a forum for the debate of system and network architecture issues. Particular emphasis was on those issues relating to the choice of multiple access technique(s) for the Mobile Satellite Service (MSS). These proceedings contain articles that expand upon the 12 presentations given in the workshop. Contrasting views on Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), and Time Division Multiple Access (TDMA)-based architectures are presented, and system issues relating to signaling, spacecraft design, and network management constraints are addressed. An overview article that summarizes the issues raised in the numerous discussion periods of the workshop is also included.

Cascaded neural networks for sequenced propagation estimation, multiuser detection, and adaptive radio resource control of third-generation wireless networks for multimedia services

NASA Astrophysics Data System (ADS)

Hortos, William S.

1999-03-01

A hybrid neural network approach is presented to estimate radio propagation characteristics and multiuser interference and to evaluate their combined impact on throughput, latency and information loss in third-generation (3G) wireless networks. The latter three performance parameters influence the quality of service (QoS) for multimedia services under consideration for 3G networks. These networks, based on a hierarchical architecture of overlaying macrocells on top of micro- and picocells, are planned to operate in mobile urban and indoor environments with service demands emanating from circuit-switched, packet-switched and satellite-based traffic sources. Candidate radio interfaces for these networks employ a form of wideband CDMA in 5-MHz and wider-bandwidth channels, with possible asynchronous operation of the mobile subscribers. The proposed neural network (NN) architecture allocates network resources to optimize QoS metrics. Parameters of the radio propagation channel are estimated, followed by control of an adaptive antenna array at the base station to minimize interference, and then joint multiuser detection is performed at the base station receiver. These adaptive processing stages are implemented as a sequence of NN techniques that provide their estimates as inputs to a final- stage Kohonen self-organizing feature map (SOFM). The SOFM optimizes the allocation of available network resources to satisfy QoS requirements for variable-rate voice, data and video services. As the first stage of the sequence, a modified feed-forward multilayer perceptron NN is trained on the pilot signals of the mobile subscribers to estimate the parameters of shadowing, multipath fading and delays on the uplinks. A recurrent NN (RNN) forms the second stage to control base stations' adaptive antenna arrays to minimize intra-cell interference. The third stage is based on a Hopfield NN (HNN), modified to detect multiple users on the uplink radio channels to mitigate multiaccess interference, control carrier-sense multiple-access (CSMA) protocols, and refine call handoff procedures. In the final stage, the Kohonen SOFM, operating in a hybrid continuous and discrete space, adaptively allocates the resources of antenna-based cell sectorization, activity monitoring, variable-rate coding, power control, handoff and caller admission to meet user demands for various multimedia services at minimum QoS levels. The performance of the NN cascade is evaluated through simulation of a candidate 3G wireless network using W-CDMA parameters in a small-cell environment. The simulated network consists of a representative number of cells. Mobile users with typical movement patterns are assumed. QoS requirements for different classes of multimedia services are considered. The proposed method is shown to provide relatively low probability of new call blocking and handoff dropping, while maintaining efficient use of the network's radio resources.

Overview of Sparse Graph for Multiple Access in Future Mobile Networks

NASA Astrophysics Data System (ADS)

Lei, Jing; Li, Baoguo; Li, Erbao; Gong, Zhenghui

2017-10-01

Multiple access via sparse graph, such as low density signature (LDS) and sparse code multiple access (SCMA), is a promising technique for future wireless communications. This survey presents an overview of the developments in this burgeoning field, including transmitter structures, extrinsic information transform (EXIT) chart analysis and comparisons with existing multiple access techniques. Such technique enables multiple access under overloaded conditions to achieve a satisfactory performance. Message passing algorithm is utilized for multi-user detection in the receiver, and structures of the sparse graph are illustrated in detail. Outlooks and challenges of this technique are also presented.

Multiple access techniques and spectrum utilization of the GLOBALSTAR mobile satellite system

NASA Astrophysics Data System (ADS)

Louie, Ming; Cohen, Michel; Rouffet, Denis; Gilhousen, Klein S.

The GLOBALSTAR System is a Low Earth Orbit (LEO) satellite-based mobile communications system that is interoperable with the current and future Public Land Mobile Network (PLMN). The GLOBALSTAR System concept is based upon technological advancement in two key areas: (1) the advancement in LEO satellite technology; (2) the advancement in cellular telephone technology, including the commercial applications of Code Division Multiple Access (CDMA) technologies, and of the most recent progress in Time Division Multiple Access technologies. The GLOBALSTAR System uses elements of CDMA, Frequency Division Multiple Access (FDMA), and Time Division Multiple Access (TDMA) technology, combining with satellite Multiple Beam Antenna (MBA) technology, to arrive at one of the most efficient modulation and multiple access system ever proposed for a satellite communications system. The technology used in GLOBALSTAR exploits the following techniques in obtaining high spectral efficiency and affordable cost per channel, with minimum coordination among different systems: power control, in open and closed loops, voice activation, spot beam satellite antenna for frequency reuse, weighted satellite antenna gain, multiple satellite coverage, and handoff between satellites. The GLOBALSTAR system design will use the following frequency bands: 1610-1626.5 MHz for up-link and 2483.5-2500 MHz for down-link.

Trellis Tone Modulation Multiple-Access for Peer Discovery in D2D Networks

PubMed Central

Lim, Chiwoo; Kim, Sang-Hyo

2018-01-01

In this paper, a new non-orthogonal multiple-access scheme, trellis tone modulation multiple-access (TTMMA), is proposed for peer discovery of distributed device-to-device (D2D) communication. The range and capacity of discovery are important performance metrics in peer discovery. The proposed trellis tone modulation uses single-tone transmission and achieves a long discovery range due to its low Peak-to-Average Power Ratio (PAPR). The TTMMA also exploits non-orthogonal resource assignment to increase the discovery capacity. For the multi-user detection of superposed multiple-access signals, a message-passing algorithm with supplementary schemes are proposed. With TTMMA and its message-passing demodulation, approximately 1.5 times the number of devices are discovered compared to the conventional frequency division multiple-access (FDMA)-based discovery. PMID:29673167

Trellis Tone Modulation Multiple-Access for Peer Discovery in D2D Networks.

PubMed

Lim, Chiwoo; Jang, Min; Kim, Sang-Hyo

2018-04-17

In this paper, a new non-orthogonal multiple-access scheme, trellis tone modulation multiple-access (TTMMA), is proposed for peer discovery of distributed device-to-device (D2D) communication. The range and capacity of discovery are important performance metrics in peer discovery. The proposed trellis tone modulation uses single-tone transmission and achieves a long discovery range due to its low Peak-to-Average Power Ratio (PAPR). The TTMMA also exploits non-orthogonal resource assignment to increase the discovery capacity. For the multi-user detection of superposed multiple-access signals, a message-passing algorithm with supplementary schemes are proposed. With TTMMA and its message-passing demodulation, approximately 1.5 times the number of devices are discovered compared to the conventional frequency division multiple-access (FDMA)-based discovery.

Hubless satellite communications networks

NASA Technical Reports Server (NTRS)

Robinson, Peter Alan

1994-01-01

Frequency Comb Multiple Access (FCMA) is a new combined modulation and multiple access method which will allow cheap hubless Very Small Aperture Terminal (VSAT) networks to be constructed. Theoretical results show bandwidth efficiency and power efficiency improvements over other modulation and multiple access methods. Costs of the VSAT network are reduced dramatically since a hub station is not required.

Multiple access capacity trade-offs for a Ka-band personal access satellite system

NASA Technical Reports Server (NTRS)

Dessouky, Khaled; Motamedi, Masoud

1990-01-01

System capability is critical to the economic viability of a personal satellite communication system. Ka band has significant potential to support a high capacity multiple access system because of the availability of bandwidth. System design tradeoffs are performed and multiple access schemes are compared with the design goal of achieving the highest capacity and efficiency. Conclusions regarding the efficiency of the different schemes and the achievable capacities are given.

Advanced multiple access concepts in mobile satellite systems

NASA Technical Reports Server (NTRS)

Ananasso, Fulvio

1990-01-01

Some multiple access strategies for Mobile Satellite Systems (MSS) are discussed. These strategies were investigated in the context of three separate studies conducted for the International Maritime Satellite Organization (INMARSAT) and the European Space Agency (ESA). Satellite-Switched Frequency Division Multiple Access (SS-FDMA), Code Division Multiple Access (CDMA), and Frequency-Addressable Beam architectures are addressed, discussing both system and technology aspects and outlining advantages and drawbacks of either solution with associated relevant hardware issues. An attempt is made to compare the considered option from the standpoint of user terminal/space segment complexity, synchronization requirements, spectral efficiency, and interference rejection.

A statistical frame based TDMA protocol for human body communication.

PubMed

Nie, Zedong; Li, Zhao; Huang, Renwei; Liu, Yuhang; Li, Jingzhen; Wang, Lei

2015-07-09

Human body communication (HBC) using the human body as the transmission medium, which has been regarded as one of the most promising short-range communications in wireless body area networks (WBAN). Compared to the traditional wireless networks, two challenges are existed in HBC based WBAN. (1) Its sensor nodes should be energy saving since it is inconvenient to replace or recharge the battery on these sensor nodes; (2) the coordinator should be able to react dynamically and rapidly to the burst traffic triggered by sensing events. Those burst traffic conditions include vital physical signal (electrocardiogram, electroencephalogram etc.) monitoring, human motion detection (fall detection, activity monitoring, gesture recognition, motion sensing etc.) and so on. To cope with aforementioned challenges, a statistical frame based TDMA (S-TDMA) protocol with multi-constrained (energy, delay, transmission efficiency and emergency management) service is proposed in this paper. The scenarios where burst traffic is often triggered rapidly with low power consumption and low delay is handled in our proposed S-TDMA. A beacon frame with the contained synchronous and poll information is designed to reduce the possibility of collisions of request frames. A statistical frame which broadcasts the unified scheduling information is adopted to avoid packet collisions, idle listening and overhearing. Dynamic time slot allocation mechanism is presented to manage the burst traffic and reduce the active period in each beacon period. An emergency mechanism is proposed for vital signals to be transmitted. The theory analysis is proceed and the result is evaluated in the hardware platform. To verify its feasibility, S-TDMA was fully implemented on our independently-developed HBC platform where four sensor nodes and a coordinator are fastened on a human body. Experiment results show that S-TDMA costs 89.397 mJ every 20 s when the payload size is 122 bytes, 9.51% lower than Lightweight MAC (LMAC); the average data latency of S-TDMA is 6.3 ms, 7.02% lower than Preamble-based TDMA (PB-TDMA); the transmission efficiency of S-TDMA is 93.67%, 4.83% higher than IEEE 802.15.6 carrier sense multiple access/collision avoidance (CSMA/CA) protocol. With respect to the challenges of HBC based WBANs, a novel S-TDMA protocol was proposed in this paper. Compared to the traditional protocols, the results demonstrate that S-TDMA successfully meets the delay and transmission efficiency requirements of HBC while keeping a low energy consumption. We also believe that our S-TDMA protocol will promote development of HBC in wearable applications.

MPH-M, AODV-M and DSR-M Performance Evaluation under Jamming Attacks.

PubMed

Del-Valle-Soto, Carolina; Mex-Perera, Carlos; Monroy, Raul; Nolazco-Flores, Juan A

2017-07-05

In this work, we present the design of a mitigation scheme for jamming attacks integrated to the routing protocols MPH, AODV, and DSR. The resulting protocols are named MPH-M (Multi-Parent Hierarchical - Modified), AODV-M (Ad hoc On Demand Distance Vector - Modified), and DSR-M (Dynamic Source Routing - Modified). For the mitigation algorithm, if the detection algorithm running locally in each node produces a positive result then the node is isolated; second, the routing protocol adapts their paths avoiding the isolated nodes. We evaluated how jamming attacks affect different metrics for all these modified protocols. The metrics we employ to detect jamming attack are number of packet retransmissions, number of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) retries while waiting for an idle channel and the energy wasted by the node. The metrics to evaluate the performance of the modified routing protocols are the throughput and resilience of the system and the energy used by the nodes. We evaluated all the modified protocols when the attacker position was set near, middle and far of the collector node. The results of our evaluation show that performance for MPH-M is much better than AODV-M and DSR-M. For example, the node energy for MPH-M is 138.13% better than AODV-M and 126.07% better than DSR-M. Moreover, we also find that MPH-M benefits much more of the mitigation scheme than AODV-M and DSR-M. For example, the node energy consumption is 34.61% lower for MPH-M and only 3.92% and 3.42% for AODV-M and DSR-M, respectively. On throughput, the MPH protocol presents a packet reception efficiency at the collector node of 16.4% on to AODV and DSR when there is no mitigation mechanism. Moreover, MPH-M has an efficiency greater than 7.7% with respect to AODV-M and DSR-M when there is a mitigation scheme. In addition, we have that with the mitigation mechanism AODV-M and DSR-M do not present noticeable modification. However, MPH-M improves its efficiency by 8.4%. We also measure the resilience of these algorithms from the average packet re-transmissions perspective, and we find that MPH-M has around a 15% lower change rate than AODV-M and DSR-M. The MPH-M recovery time is 5 s faster than AODV-M and 2 s faster than DSR-M.

MPH-M, AODV-M and DSR-M Performance Evaluation under Jamming Attacks

PubMed Central

Del-Valle-Soto, Carolina

2017-01-01

In this work, we present the design of a mitigation scheme for jamming attacks integrated to the routing protocols MPH, AODV, and DSR. The resulting protocols are named MPH-M (Multi-Parent Hierarchical - Modified), AODV-M (Ad hoc On Demand Distance Vector - Modified), and DSR-M (Dynamic Source Routing - Modified). For the mitigation algorithm, if the detection algorithm running locally in each node produces a positive result then the node is isolated; second, the routing protocol adapts their paths avoiding the isolated nodes. We evaluated how jamming attacks affect different metrics for all these modified protocols. The metrics we employ to detect jamming attack are number of packet retransmissions, number of CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) retries while waiting for an idle channel and the energy wasted by the node. The metrics to evaluate the performance of the modified routing protocols are the throughput and resilience of the system and the energy used by the nodes. We evaluated all the modified protocols when the attacker position was set near, middle and far of the collector node. The results of our evaluation show that performance for MPH-M is much better than AODV-M and DSR-M. For example, the node energy for MPH-M is 138.13% better than AODV-M and 126.07% better than DSR-M. Moreover, we also find that MPH-M benefits much more of the mitigation scheme than AODV-M and DSR-M. For example, the node energy consumption is 34.61% lower for MPH-M and only 3.92% and 3.42% for AODV-M and DSR-M, respectively. On throughput, the MPH protocol presents a packet reception efficiency at the collector node of 16.4% on to AODV and DSR when there is no mitigation mechanism. Moreover, MPH-M has an efficiency greater than 7.7% with respect to AODV-M and DSR-M when there is a mitigation scheme. In addition, we have that with the mitigation mechanism AODV-M and DSR-M do not present noticeable modification. However, MPH-M improves its efficiency by 8.4%. We also measure the resilience of these algorithms from the average packet re-transmissions perspective, and we find that MPH-M has around a 15% lower change rate than AODV-M and DSR-M. The MPH-M recovery time is 5 s faster than AODV-M and 2 s faster than DSR-M. PMID:28678180

Spread-spectrum multiple access using wideband noncoherent MFSK

NASA Technical Reports Server (NTRS)

Ha, Tri T.; Pratt, Timothy; Maggenti, Mark A.

1987-01-01

Two spread-spectrum multiple access systems which use wideband M-ary frequency shift keying (FSK) (MFSK) as the primary modulation are presented. A bit error rate performance analysis is presented and system throughput is calculated for sample C band and Ku band satellite systems. Sample link analyses are included to illustrate power and adjacent satellite interference considerations in practical multiple access systems.

Methods and devices for determining quality of services of storage systems

DOEpatents

Seelam, Seetharami R [Yorktown Heights, NY; Teller, Patricia J [Las Cruces, NM

2012-01-17

Methods and systems for allowing access to computer storage systems. Multiple requests from multiple applications can be received and processed efficiently to allow traffic from multiple customers to access the storage system concurrently.

Mobile multiple access study

NASA Technical Reports Server (NTRS)

1977-01-01

Multiple access techniques (FDMA, CDMA, TDMA) for the mobile user and attempts to identify the current best technique are discussed. Traffic loading is considered as well as voice and data modulation and spacecraft and system design. Emphasis is placed on developing mobile terminal cost estimates for the selected design. In addition, design examples are presented for the alternative techniques of multiple access in order to compare with the selected technique.

Distributed reservation-based code division multiple access

NASA Astrophysics Data System (ADS)

Wieselthier, J. E.; Ephremides, A.

1984-11-01

The use of spread spectrum signaling, motivated primarily by its antijamming capabilities in military applications, leads naturally to the use of Code Division Multiple Access (CDMA) techniques that permit the successful simultaneous transmission by a number of users over a wideband channel. In this paper we address some of the major issues that are associated with the design of multiple access protocols for spread spectrum networks. We then propose, analyze, and evaluate a distributed reservation-based multiple access protocol that does in fact exploit CDMA properties. Especially significant is the fact that no acknowledgment or feedback information from the destination is required (thus facilitating communication with a radio-silent mode), nor is any form of coordination among the users necessary.

Traffic handling capability of a broadband indoor wireless network using CDMA multiple access

NASA Astrophysics Data System (ADS)

Zhang, Chang G.; Hafez, H. M.; Falconer, David D.

1994-05-01

CDMA (code division multiple access) may be an attractive technique for wireless access to broadband services because of its multiple access simplicity and other appealing features. In order to investigate traffic handling capabilities of a future network providing a variety of integrated services, this paper presents a study of a broadband indoor wireless network supporting high-speed traffic using CDMA multiple access. The results are obtained through the simulation of an indoor environment and the traffic capabilities of the wireless access to broadband 155.5 MHz ATM-SONET networks using the mm-wave band. A distributed system architecture is employed and the system performance is measured in terms of call blocking probability and dropping probability. The impacts of the base station density, traffic load, average holding time, and variable traffic sources on the system performance are examined. The improvement of system performance by implementing various techniques such as handoff, admission control, power control and sectorization are also investigated.

Development of the Average Likelihood Function for Code Division Multiple Access (CDMA) Using BPSK and QPSK Symbols

DTIC Science & Technology

2015-01-01

This research has the purpose to establish a foundation for new classification and estimation of CDMA signals. Keywords: DS / CDMA signals, BPSK, QPSK...DEVELOPMENT OF THE AVERAGE LIKELIHOOD FUNCTION FOR CODE DIVISION MULTIPLE ACCESS ( CDMA ) USING BPSK AND QPSK SYMBOLS JANUARY 2015...To) OCT 2013 – OCT 2014 4. TITLE AND SUBTITLE DEVELOPMENT OF THE AVERAGE LIKELIHOOD FUNCTION FOR CODE DIVISION MULTIPLE ACCESS ( CDMA ) USING BPSK

Pulse patterning effect in optical pulse division multiplexing for flexible single wavelength multiple access optical network

NASA Astrophysics Data System (ADS)

Jung, Sun-Young; Kim, Chang-Hun; Han, Sang-Kook

2018-05-01

A demand for high spectral efficiency requires multiple access within a single wavelength, but the uplink signals are significantly degraded because of optical beat interference (OBI) in intensity modulation/direct detection system. An optical pulse division multiplexing (OPDM) technique was proposed that could effectively reduce the OBI via a simple method as long as near-orthogonality is satisfied, but the condition was strict, and thus, the number of multiplexing units was very limited. We propose pulse pattern enhanced OPDM (e-OPDM) to reduce the OBI and improve the flexibility in multiple access within a single wavelength. The performance of the e-OPDM and patterning effect are experimentally verified after 23-km single mode fiber transmission. By employing pulse patterning in OPDM, the tight requirement was relaxed by extending the optical delay dynamic range. This could support more number of access with reduced OBI, which could eventually enhance a multiple access function.

Mof-Tree: A Spatial Access Method To Manipulate Multiple Overlapping Features.

ERIC Educational Resources Information Center

Manolopoulos, Yannis; Nardelli, Enrico; Papadopoulos, Apostolos; Proietti, Guido

1997-01-01

Investigates the manipulation of large sets of two-dimensional data representing multiple overlapping features, and presents a new access method, the MOF-tree. Analyzes storage requirements and time with respect to window query operations involving multiple features. Examines both the pointer-based and pointerless MOF-tree representations.…

Universal filtered multi-carrier system for asynchronous uplink transmission in optical access network

NASA Astrophysics Data System (ADS)

Kang, Soo-Min; Kim, Chang-Hun; Han, Sang-Kook

2016-02-01

In passive optical network (PON), orthogonal frequency division multiplexing (OFDM) has been studied actively due to its advantages such as high spectra efficiency (SE), dynamic resource allocation in time or frequency domain, and dispersion robustness. However, orthogonal frequency division multiple access (OFDMA)-PON requires tight synchronization among multiple access signals. If not, frequency orthogonality could not be maintained. Also its sidelobe causes inter-channel interference (ICI) to adjacent channel. To prevent ICI caused by high sidelobes, guard band (GB) is usually used which degrades SE. Thus, OFDMA-PON is not suitable for asynchronous uplink transmission in optical access network. In this paper, we propose intensity modulation/direct detection (IM/DD) based universal filtered multi-carrier (UFMC) PON for asynchronous multiple access. The UFMC uses subband filtering to subsets of subcarriers. Since it reduces sidelobe of each subband by applying subband filtering, it could achieve better performance compared to OFDM. For the experimental demonstration, different sample delay was applied to subbands to implement asynchronous transmission condition. As a result, time synchronization robustness of UFMC was verified in asynchronous multiple access system.

Opportunistic Access in Frequency Hopping Cognitive Radio Networks

DTIC Science & Technology

2014-03-27

thresholding MA multiple access MFSK M-ary frequency shift keying MIMO multiple-input/multiple-output OFDM orthogonal frequency-division multiplexing x...adaptive BER performance as a function of ISR with orthogonal frequency-division multiplexing ( OFDM ) interference present. . . . . . . . . . 41 4.15 Non...adaptive BER performance as a function of EB/N0 with OFDM interfer- ence present

Performance analysis of local area networks

NASA Technical Reports Server (NTRS)

Alkhatib, Hasan S.; Hall, Mary Grace

1990-01-01

A simulation of the TCP/IP protocol running on a CSMA/CD data link layer was described. The simulation was implemented using the simula language, and object oriented discrete event language. It allows the user to set the number of stations at run time, as well as some station parameters. Those parameters are the interrupt time and the dma transfer rate for each station. In addition, the user may configure the network at run time with stations of differing characteristics. Two types are available, and the parameters of both types are read from input files at run time. The parameters include the dma transfer rate, interrupt time, data rate, average message size, maximum frame size and the average interarrival time of messages per station. The information collected for the network is the throughput and the mean delay per packet. For each station, the number of messages attempted as well as the number of messages successfully transmitted is collected in addition to the throughput and mean packet delay per station.

Design of pulse waveform for waveform division multiple access UWB wireless communication system.

PubMed

Yin, Zhendong; Wang, Zhirui; Liu, Xiaohui; Wu, Zhilu

2014-01-01

A new multiple access scheme, Waveform Division Multiple Access (WDMA) based on the orthogonal wavelet function, is presented. After studying the correlation properties of different categories of single wavelet functions, the one with the best correlation property will be chosen as the foundation for combined waveform. In the communication system, each user is assigned to different combined orthogonal waveform. Demonstrated by simulation, combined waveform is more suitable than single wavelet function to be a communication medium in WDMA system. Due to the excellent orthogonality, the bit error rate (BER) of multiuser with combined waveforms is so close to that of single user in a synchronous system. That is to say, the multiple access interference (MAI) is almost eliminated. Furthermore, even in an asynchronous system without multiuser detection after matched filters, the result is still pretty ideal and satisfactory by using the third combination mode that will be mentioned in the study.

Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation

NASA Technical Reports Server (NTRS)

Wang, C.-W.; Stark, W.

2005-01-01

This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shift-keying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shift-keying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near-far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near-far effect that occurs in a multiple-access environment than are the more protected bits.

Frequency comb-based multiple-access ultrastable frequency dissemination with 7 × 10(-17) instability.

PubMed

Zhang, Shuangyou; Zhao, Jianye

2015-01-01

In this letter, we demonstrate frequency-comb-based multiple-access ultrastable frequency dissemination over a 10-km single-mode fiber link. First, we synchronize optical pulse trains from an Er-fiber frequency comb to the remote site by using a simple and robust phase-conjugate stabilization method. The fractional frequency-transfer instability at the remote site is 2.6×10(-14) and 4.9×10(-17) for averaging times of 1 and 10,000 s, respectively. Then, we reproduce the harmonic of the repetition rate from the disseminated optical pulse trains at an arbitrary point along the fiber link to test comb-based multiple-access performance, and demonstrate frequency instability of 4×10(-14) and 7×10(-17) at 1 and 10,000 s averaging time, respectively. The proposed comb-based multiple-access frequency dissemination can easily achieve highly stable wideband microwave extraction along the whole link.

AEROSAT Access Control Summary

DOT National Transportation Integrated Search

1976-10-01

The report consists of three basic sections. Section 2 is a discussion of the communications concepts germane to AEROSAT access control. It defines and reviews the principles of multiplexing, multiple access, demand access, and access control and rel...

Aerosat Access Control Summary

DOT National Transportation Integrated Search

1976-10-01

The report consists of three basic sections. Section 2 is a discussion of the communications concepts germane to AEROSAT access control. It defines and reviews the principles of multiplexing, multiple access, demand access, and access control and rel...

Querying and Computing with BioCyc Databases

PubMed Central

Krummenacker, Markus; Paley, Suzanne; Mueller, Lukas; Yan, Thomas; Karp, Peter D.

2006-01-01

Summary We describe multiple methods for accessing and querying the complex and integrated cellular data in the BioCyc family of databases: access through multiple file formats, access through Application Program Interfaces (APIs) for LISP, Perl and Java, and SQL access through the BioWarehouse relational database. Availability The Pathway Tools software and 20 BioCyc DBs in Tiers 1 and 2 are freely available to academic users; fees apply to some types of commercial use. For download instructions see http://BioCyc.org/download.shtml PMID:15961440

Post-Coma Persons with Extensive Multiple Disabilities Use Microswitch Technology to Access Selected Stimulus Events or Operate a Radio Device

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Alberti, Gloria; Oliva, Doretta; Megna, Gianfranco; Iliceto, Carla; Damiani, Sabino; Ricci, Irene; Spica, Antonella

2011-01-01

The present two studies extended research evidence on the use of microswitch technology by post-coma persons with multiple disabilities. Specifically, Study I examined whether three adults with a diagnosis of minimally conscious state and multiple disabilities could use microswitches as tools to access brief, selected stimulus events. Study II…

Gambling involvement and increased risk of gambling problems.

PubMed

Phillips, James G; Ogeil, Rowan; Chow, Yang-Wai; Blaszczynski, Alex

2013-12-01

The opportunity to gamble has undergone rapid expansion with technology allowing for access to gambling products 24 h a day. This increased online availability challenges governments' abilities to restrict access to gambling. Indeed, the ready access to multiple forms of gambling may potentially contribute to impaired control over urges for problem gamblers. The present study considered whether problem gamblers manifested a tendency to engage in multiple forms of gambling and identified forms of gambling which were more strongly related to problem gambling. In reanalyses of two surveys (Sample 1, N = 464, Sample 2, N = 1141), significant relationships accounting for between 11.3 and 13.5% of the variance were found between the numbers of forms of gambling accessed and degree of problem. Participation in online poker, playing cards and sports wagering were linked to problem gambling. Access to multiple forms of gambling may pose difficulties for the tracking and control of gambling.

Quantum internet using code division multiple access

PubMed Central

Zhang, Jing; Liu, Yu-xi; Özdemir, Şahin Kaya; Wu, Re-Bing; Gao, Feifei; Wang, Xiang-Bin; Yang, Lan; Nori, Franco

2013-01-01

A crucial open problem inS large-scale quantum networks is how to efficiently transmit quantum data among many pairs of users via a common data-transmission medium. We propose a solution by developing a quantum code division multiple access (q-CDMA) approach in which quantum information is chaotically encoded to spread its spectral content, and then decoded via chaos synchronization to separate different sender-receiver pairs. In comparison to other existing approaches, such as frequency division multiple access (FDMA), the proposed q-CDMA can greatly increase the information rates per channel used, especially for very noisy quantum channels. PMID:23860488

Design analysis tracking and data relay satellite simulation system

NASA Technical Reports Server (NTRS)

1974-01-01

The design and development of the equipment necessary to simulate the S-band multiple access link between user spacecraft, the Tracking and Data Relay Satellite, and a ground control terminal are discussed. The core of the S-band multiple access concept is the use of an Adaptive Ground Implemented Phased Array. The array contains thirty channels and provides the multiplexing and demultiplexing equipment required to demonstrate the ground implemented beam forming feature. The system provided will make it possible to demonstrate the performance of a desired user and ten interfering sources attempting to pass data through the multiple access system.

Frequency Hopping, Multiple Frequency-Shift Keying, Coding, and Optimal Partial-Band Jamming.

DTIC Science & Technology

1982-08-01

receivers appropriate for these two strategies. Each receiver is noncoherent (a coherent receiver is generally impractical) and implements hard...Advances in Coding and Modulation for Noncoherent Channels Affected by Fading, Partial Band, and Multiple- . Access Interference, in A. J. Viterbi...Modulation for Noncoherent Channels Affected by Fading, Partial Band, and Multiple-Access interference, in A. J. Viterbi, ed., Advances in Coumunication

Clandestine Transmissions and Operations of Embedded Software on Cellular Mobile Devices

DTIC Science & Technology

2011-09-01

Register EMS Enhanced Message Service FDMA Frequency Division Multiple Access GMT Greenwich Mean Time GMSC Gateway Mobile Switching Center...Message Switching Center SMS-IWMSC SMS-Interworking Mobile-Service Switching Center TCH Traffic Channels TDMA Time Division Multiple Access TP...assume the user will not attempt to re-program the device. Finally, we assume that the owner and user do not have root access and cannot disable any

An Architecture for Enabling Migration of Tactical Networks to Future Flexible Ad Hoc WBWF

DTIC Science & Technology

2010-09-01

Requirements Several multiple access schemes TDMA OFDMA SC-OFDMA, FH- CDMA , DS - CDMA , hybrid access schemes, transitions between them Dynamic...parameters algorithms depend on the multiple access scheme If DS - CDMA : handling of macro-diversity (linked to cooperative routing) TDMA and/of OFDMA...Transport format Ciphering @MAC/RLC level : SCM Physical layer (PHY) : signal processing (mod, FEC, etc) CDMA : macro-diversity CDMA , OFDMA

Full Duplex, Spread Spectrum Radio System

NASA Technical Reports Server (NTRS)

Harvey, Bruce A.

2000-01-01

The goal of this project was to support the development of a full duplex, spread spectrum voice communications system. The assembly and testing of a prototype system consisting of a Harris PRISM spread spectrum radio, a TMS320C54x signal processing development board and a Zilog Z80180 microprocessor was underway at the start of this project. The efforts under this project were the development of multiple access schemes, analysis of full duplex voice feedback delays, and the development and analysis of forward error correction (FEC) algorithms. The multiple access analysis involved the selection between code division multiple access (CDMA), frequency division multiple access (FDMA) and time division multiple access (TDMA). Full duplex voice feedback analysis involved the analysis of packet size and delays associated with full loop voice feedback for confirmation of radio system performance. FEC analysis included studies of the performance under the expected burst error scenario with the relatively short packet lengths, and analysis of implementation in the TMS320C54x digital signal processor. When the capabilities and the limitations of the components used were considered, the multiple access scheme chosen was a combination TDMA/FDMA scheme that will provide up to eight users on each of three separate frequencies. Packets to and from each user will consist of 16 samples at a rate of 8,000 samples per second for a total of 2 ms of voice information. The resulting voice feedback delay will therefore be 4 - 6 ms. The most practical FEC algorithm for implementation was a convolutional code with a Viterbi decoder. Interleaving of the bits of each packet will be required to offset the effects of burst errors.

Adaptive receiver structures for asynchronous CDMA systems

NASA Astrophysics Data System (ADS)

Rapajic, Predrag B.; Vucetic, Branka S.

1994-05-01

Adaptive linear and decision feedback receiver structures for coherent demodulation in asynchronous code division multiple access (CDMA) systems are considered. It is assumed that the adaptive receiver has no knowledge of the signature waveforms and timing of other users. The receiver is trained by a known training sequence prior to data transmission and continuously adjusted by an adaptive algorithm during data transmission. The proposed linear receiver is as simple as a standard single-user detector receiver consisting of a matched filter with constant coefficients, but achieves essential advantages with respect to timing recovery, multiple access interference elimination, near/far effect, narrowband and frequency-selective fading interference suppression, and user privacy. An adaptive centralized decision feedback receiver has the same advantages of the linear receiver but, in addition, achieves a further improvement in multiple access interference cancellation at the expense of higher complexity. The proposed receiver structures are tested by simulation over a channel with multipath propagation, multiple access interference, narrowband interference, and additive white Gaussian noise.

A comparison of Frequency Domain Multiple Access (FDMA) and Time Domain Multiple Access (TDMA) approaches to satellite service for low data rate Earth stations

NASA Technical Reports Server (NTRS)

Stevens, G.

1983-01-01

A technological and economic assessment is made of providing low data rate service to small earth stations by satellite at Ka-band. Various Frequency Domain Multiple Access (FDMA) and Time Domain Multiple Access (TDMA) scenarios are examined and compared on the basis of cost to the end user. Very small stations (1 to 2 meters in diameter) are found not to be viable alternatives to available terrestrial services. However, medium size (3 to 5 meters) earth stations appear to be very competitive if a minimum throughput of about 1.5 Mbs is maintained. This constrains the use of such terminals to large users and shared use by smaller users. No advantage was found to the use of FDMA. TDMA had a slight advantage from a total system viewpoint and a very significant advantage in the space segment (about 1/3 the required payload weight for an equivalent capacity).

Evaluation of CDMA system capacity for mobile satellite system applications

NASA Technical Reports Server (NTRS)

Smith, Partrick O.; Geraniotis, Evaggelos A.

1988-01-01

A specific Direct-Sequence/Pseudo-Noise (DS/PN) Code-Division Multiple-Access (CDMA) mobile satellite system (MSAT) architecture is discussed. The performance of this system is evaluated in terms of the maximum number of active MSAT subscribers that can be supported at a given uncoded bit-error probability. The evaluation decouples the analysis of the multiple-access capability (i.e., the number of instantaneous user signals) from the analysis of the multiple-access mutliplier effect allowed by the use of CDMA with burst-modem operation. We combine the results of these two analyses and present numerical results for scenarios of interest to the mobile satellite system community.

Asynchronous, Decentralized DS-CDMA Using Feedback-Controlled Spreading Sequences for Time-Dispersive Channels

NASA Astrophysics Data System (ADS)

Miyatake, Teruhiko; Chiba, Kazuki; Hamamura, Masanori; Tachikawa, Shin'ichi

We propose a novel asynchronous direct-sequence codedivision multiple access (DS-CDMA) using feedback-controlled spreading sequences (FCSSs) (FCSS/DS-CDMA). At the receiver of FCSS/DS-CDMA, the code-orthogonalizing filter (COF) produces a spreading sequence, and the receiver returns the spreading sequence to the transmitter. Then the transmitter uses the spreading sequence as its updated version. The performance of FCSS/DS-CDMA is evaluated over time-dispersive channels. The results indicate that FCSS/DS-CDMA greatly suppresses both the intersymbol interference (ISI) and multiple access interference (MAI) over time-invariant channels. FCSS/DS-CDMA is applicable to the decentralized multiple access.

A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

NASA Technical Reports Server (NTRS)

Wallett, Thomas M.

2009-01-01

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements.

Binary Sequences for Spread-Spectrum Multiple-Access Communication

DTIC Science & Technology

1977-08-01

Massey, J. L., and Uhran, J. J., Jr., "Sub-baud coding," Proceedings of the Thirteenth Annual Allerton Conference on Circuit and System Theory, pp. 539...sequences in a multipl.e access environment," Proceedings of the Thirteenth Annual AIlerton Conference on Circuit and System Theory, pp. 21-27, October...34 Proceedings of the Thirteenth Annual Allertcn Conference on Circuit and System Theory, pp. 548-559, October 1975. Yao, K., *Performance bounds on

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases.

PubMed

Kumar, Sundeep; Archak, Sunil; Tyagi, R K; Kumar, Jagdish; Vk, Vikas; Jacob, Sherry R; Srinivasan, Kalyani; Radhamani, J; Parimalan, R; Sivaswamy, M; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N S; Chowdhury, A K; Saha, B C; Bhattacharya, P M; Kumari, Jyoti; Singh, M C; Gangwar, O P; Prasad, P; Bharadwaj, S C; Gogoi, Robin; Sharma, J B; Gm, Sandeep Kumar; Saharan, M S; Bag, Manas; Roy, Anirban; Prasad, T V; Sharma, R K; Dutta, M; Sharma, Indu; Bansal, K C

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat-Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011-14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels.

Evaluation of 19,460 Wheat Accessions Conserved in the Indian National Genebank to Identify New Sources of Resistance to Rust and Spot Blotch Diseases

PubMed Central

Jacob, Sherry R.; Srinivasan, Kalyani; Radhamani, J.; Parimalan, R.; Sivaswamy, M.; Tyagi, Sandhya; Yadav, Mamata; Kumari, Jyotisna; Deepali; Sharma, Sandeep; Bhagat, Indoo; Meeta, Madhu; Bains, N. S.; Chowdhury, A. K.; Saha, B. C.; Bhattacharya, P. M.; Kumari, Jyoti; Singh, M. C.; Gangwar, O. P.; Prasad, P.; Bharadwaj, S. C.; Gogoi, Robin; Sharma, J. B.; GM, Sandeep Kumar; Saharan, M. S.; Bag, Manas; Roy, Anirban; Prasad, T. V.; Sharma, R. K.; Dutta, M.; Sharma, Indu; Bansal, K. C.

2016-01-01

A comprehensive germplasm evaluation study of wheat accessions conserved in the Indian National Genebank was conducted to identify sources of rust and spot blotch resistance. Genebank accessions comprising three species of wheat–Triticum aestivum, T. durum and T. dicoccum were screened sequentially at multiple disease hotspots, during the 2011–14 crop seasons, carrying only resistant accessions to the next step of evaluation. Wheat accessions which were found to be resistant in the field were then assayed for seedling resistance and profiled using molecular markers. In the primary evaluation, 19,460 accessions were screened at Wellington (Tamil Nadu), a hotspot for wheat rusts. We identified 4925 accessions to be resistant and these were further evaluated at Gurdaspur (Punjab), a hotspot for stripe rust and at Cooch Behar (West Bengal), a hotspot for spot blotch. The second round evaluation identified 498 accessions potentially resistant to multiple rusts and 868 accessions potentially resistant to spot blotch. Evaluation of rust resistant accessions for seedling resistance against seven virulent pathotypes of three rusts under artificial epiphytotic conditions identified 137 accessions potentially resistant to multiple rusts. Molecular analysis to identify different combinations of genetic loci imparting resistance to leaf rust, stem rust, stripe rust and spot blotch using linked molecular markers, identified 45 wheat accessions containing known resistance genes against all three rusts as well as a QTL for spot blotch resistance. The resistant germplasm accessions, particularly against stripe rust, identified in this study can be excellent potential candidates to be employed for breeding resistance into the background of high yielding wheat cultivars through conventional or molecular breeding approaches, and are expected to contribute toward food security at national and global levels. PMID:27942031

Heterodyne detection using spectral line pairing for spectral phase encoding optical code division multiple access and dynamic dispersion compensation.

PubMed

Yang, Yi; Foster, Mark; Khurgin, Jacob B; Cooper, A Brinton

2012-07-30

A novel coherent optical code-division multiple access (OCDMA) scheme is proposed that uses spectral line pairing to generate signals suitable for heterodyne decoding. Both signal and local reference are transmitted via a single optical fiber and a simple balanced receiver performs sourceless heterodyne detection, canceling speckle noise and multiple-access interference (MAI). To validate the idea, a 16 user fully loaded phase encoded system is simulated. Effects of fiber dispersion on system performance are studied as well. Both second and third order dispersion management is achieved by using a spectral phase encoder to adjust phase shifts of spectral components at the optical network unit (ONU).

Comparison of CDMA and FDMA for the MobileStar(sm) system

NASA Technical Reports Server (NTRS)

Jacobs, I. M.; Gilhousen, K. S.; Weaver, L. A.; Renshaw, K.; Murphy, T.

1988-01-01

Spread-spectrum code division multiple access (CDMA) and single channel per carrier frequency division multiple access (FDMA) systems are compared for spectrum efficiency. CDMA is shown to have greater maximum throughput than FDMA for the MobileStar(sm) system which uses digital voice activated carriers and directive circularly polarized satellite antennas.

Wireless Computing Architecture III

DTIC Science & Technology

2013-09-01

MIMO Multiple-Input and Multiple-Output MIMO /CON MIMO with concurrent hannel access and estimation MU- MIMO Multiuser MIMO OFDM Orthogonal...compressive sensing \\; a design for concurrent channel estimation in scalable multiuser MIMO networking; and novel networking protocols based on machine...Network, Antenna Arrays, UAV networking, Angle of Arrival, Localization MIMO , Access Point, Channel State Information, Compressive Sensing 16

Electromagnetic interference-aware transmission scheduling and power control for dynamic wireless access in hospital environments.

PubMed

Phunchongharn, Phond; Hossain, Ekram; Camorlinga, Sergio

2011-11-01

We study the multiple access problem for e-Health applications (referred to as secondary users) coexisting with medical devices (referred to as primary or protected users) in a hospital environment. In particular, we focus on transmission scheduling and power control of secondary users in multiple spatial reuse time-division multiple access (STDMA) networks. The objective is to maximize the spectrum utilization of secondary users and minimize their power consumption subject to the electromagnetic interference (EMI) constraints for active and passive medical devices and minimum throughput guarantee for secondary users. The multiple access problem is formulated as a dual objective optimization problem which is shown to be NP-complete. We propose a joint scheduling and power control algorithm based on a greedy approach to solve the problem with much lower computational complexity. To this end, an enhanced greedy algorithm is proposed to improve the performance of the greedy algorithm by finding the optimal sequence of secondary users for scheduling. Using extensive simulations, the tradeoff in performance in terms of spectrum utilization, energy consumption, and computational complexity is evaluated for both the algorithms.

Multiple Intimate Partner Violence Experiences: Knowledge, Access, Utilization and Barriers to Utilization of Resources by Women of the African Diaspora.

PubMed

Sabri, Bushra; Huerta, Julia; Alexander, Kamila A; St Vil, Noelle M; Campbell, Jacquelyn C; Callwood, Gloria B

2015-11-01

This study examined knowledge, access, utilization, and barriers to use of resources among Black women exposed to multiple types of intimate partner violence in Baltimore, Maryland and the U.S. Virgin Islands (USVI). We analyzed quantitative survey data collected by 163 women recruited from primary care, prenatal or family planning clinics in Baltimore and the USVI. In addition we analyzed qualitative data from in-depth interviews with 11 women. Quantitative data were analyzed using descriptive statistics and qualitative data were analyzed using thematic analysis. A substantial proportion of Black women with multiple types of violence experiences lacked knowledge of, did not have access to, and did not use resources. Barriers to resource use were identified at the individual, relationship, and community levels. There is need for programs to develop awareness, promote access and utilization of resources, and eliminate barriers to resource use among abused Black women.

Distributed reservation control protocols for random access broadcasting channels

NASA Technical Reports Server (NTRS)

Greene, E. P.; Ephremides, A.

1981-01-01

Attention is given to a communication network consisting of an arbitrary number of nodes which can communicate with each other via a time-division multiple access (TDMA) broadcast channel. The reported investigation is concerned with the development of efficient distributed multiple access protocols for traffic consisting primarily of single packet messages in a datagram mode of operation. The motivation for the design of the protocols came from the consideration of efficient multiple access utilization of moderate to high bandwidth (4-40 Mbit/s capacity) communication satellite channels used for the transmission of short (1000-10,000 bits) fixed length packets. Under these circumstances, the ratio of roundtrip propagation time to packet transmission time is between 100 to 10,000. It is shown how a TDMA channel can be adaptively shared by datagram traffic and constant bandwidth users such as in digital voice applications. The distributed reservation control protocols described are a hybrid between contention and reservation protocols.

Multiple-choice tests stabilize access to marginal knowledge.

PubMed

Cantor, Allison D; Eslick, Andrea N; Marsh, Elizabeth J; Bjork, Robert A; Bjork, Elizabeth Ligon

2015-02-01

Marginal knowledge refers to knowledge that is stored in memory, but is not accessible at a given moment. For example, one might struggle to remember who wrote The Call of the Wild, even if that knowledge is stored in memory. Knowing how best to stabilize access to marginal knowledge is important, given that new learning often requires accessing and building on prior knowledge. While even a single opportunity to restudy marginal knowledge boosts its later accessibility (Berger, Hall, & Bahrick, 1999), in many situations explicit relearning opportunities are not available. Our question is whether multiple-choice tests (which by definition expose the learner to the correct answers) can also serve this function and, if so, how testing compares to restudying given that tests can be particularly powerful learning devices (Roediger & Karpicke, 2006). In four experiments, we found that multiple-choice testing had the power to stabilize access to marginal knowledge, and to do so for at least up to a week. Importantly, such tests did not need to be paired with feedback, although testing was no more powerful than studying. Overall, the results support the idea that one's knowledge base is unstable, with individual pieces of information coming in and out of reach. The present findings have implications for a key educational challenge: ensuring that students have continuing access to information they have learned.

Performance Analysis of a New Coded TH-CDMA Scheme in Dispersive Infrared Channel with Additive Gaussian Noise

NASA Astrophysics Data System (ADS)

Hamdi, Mazda; Kenari, Masoumeh Nasiri

2013-06-01

We consider a time-hopping based multiple access scheme introduced in [1] for communication over dispersive infrared links, and evaluate its performance for correlator and matched filter receivers. In the investigated time-hopping code division multiple access (TH-CDMA) method, the transmitter benefits a low rate convolutional encoder. In this method, the bit interval is divided into Nc chips and the output of the encoder along with a PN sequence assigned to the user determines the position of the chip in which the optical pulse is transmitted. We evaluate the multiple access performance of the system for correlation receiver considering background noise which is modeled as White Gaussian noise due to its large intensity. For the correlation receiver, the results show that for a fixed processing gain, at high transmit power, where the multiple access interference has the dominant effect, the performance improves by the coding gain. But at low transmit power, in which the increase of coding gain leads to the decrease of the chip time, and consequently, to more corruption due to the channel dispersion, there exists an optimum value for the coding gain. However, for the matched filter, the performance always improves by the coding gain. The results show that the matched filter receiver outperforms the correlation receiver in the considered cases. Our results show that, for the same bandwidth and bit rate, the proposed system excels other multiple access techniques, like conventional CDMA and time hopping scheme.

System access control study

DOT National Transportation Integrated Search

1974-06-01

The report presents a summary of a study conducted for the Transportation Systems Center of promising access control techniques which are applicable to an aeronautical satellite system. Several frequency division multiple access (FDMA) and time divis...

Full-band TDM-OPDMA for OBI-reduced simultaneous multiple access in a single-wavelength optical access network.

PubMed

Jung, Sun-Young; Kim, Chang-Hun; Han, Sang-Kook

2018-05-14

Simultaneous multiple access (MA) within a single wavelength can increase the data rate and split ratio in a passive optical network while optical beat interference (OBI) becomes serious in the uplink. Previous techniques to reduce OBI were limited by their complexity and lack of extendibility; as well, bandwidth allocation among MA signals is needed for single photo diode (PD) detection. We proposed and experimentally demonstrated full-band optical pulse division multiplexing-based MA (OPDMA) in an optical access network, which can effectively reduce OBI with extendibility and fully utilize frequency resources of optical modulator without bandwidth allocation in a single-wavelength MA.

On board processing for future satellite communications systems: Comparison of FDM, TDM and hybrid accessing schemes

NASA Technical Reports Server (NTRS)

Berk, G.; Jean, P. N.; Rotholz, E.

1982-01-01

Several satellite uplink and downlink accessing schemes for customer premises service are compared. Four conceptual system designs are presented: satellite-routed frequency division multiple access (FDMA), satellite-switched time division multiple access (TDMA), processor-routed TDMA, and frequency-routed TDMA, operating in the 30/20 GHz band. The designs are compared on the basis of estimated satellite weight, system capacity, power consumption, and cost. The systems are analyzed for fixed multibeam coverage of the continental United States. Analysis shows that the system capacity is limited by the available satellite resources and by the terminal size and cost.

Mobile and Accessible Learning for MOOCs

ERIC Educational Resources Information Center

Sharples, Mike; Kloos, Carlos Delgado; Dimitriadis, Yannis; Garlatti, Serge; Specht, Marcus

2015-01-01

Many modern web-based systems provide a "responsive" design that allows material and services to be accessed on mobile and desktop devices, with the aim of providing "ubiquitous access." Besides offering access to learning materials such as podcasts and videos across multiple locations, mobile, wearable and ubiquitous…

Study of spread spectrum multiple access systems for satellite communications with overlay on current services

NASA Technical Reports Server (NTRS)

Ha, Tri T.; Pratt, Timothy

1989-01-01

The feasibility of using spread spectrum techniques to provide a low-cost multiple access system for a very large number of low data terminals was investigated. Two applications of spread spectrum technology to very small aperture terminal (VSAT) satellite communication networks are presented. Two spread spectrum multiple access systems which use a form of noncoherent M-ary FSK (MFSK) as the primary modulation are described and the throughput analyzed. The analysis considers such factors as satellite power constraints and adjacent satellite interference. Also considered is the effect of on-board processing on the multiple access efficiency and the feasibility of overlaying low data rate spread spectrum signals on existing satellite traffic as a form of frequency reuse is investigated. The use of chirp is examined for spread spectrum communications. In a chirp communication system, each data bit is converted into one or more up or down sweeps of frequency, which spread the RF energy across a broad range of frequencies. Several different forms of chirp communication systems are considered, and a multiple-chirp coded system is proposed for overlay service. The mutual interference problem is examined in detail and a performance analysis undertaken for the case of a chirp data channel overlaid on a video channel.

Optimal Resource Allocation for NOMA-TDMA Scheme with α-Fairness in Industrial Internet of Things.

PubMed

Sun, Yanjing; Guo, Yiyu; Li, Song; Wu, Dapeng; Wang, Bin

2018-05-15

In this paper, a joint non-orthogonal multiple access and time division multiple access (NOMA-TDMA) scheme is proposed in Industrial Internet of Things (IIoT), which allowed multiple sensors to transmit in the same time-frequency resource block using NOMA. The user scheduling, time slot allocation, and power control are jointly optimized in order to maximize the system α -fair utility under transmit power constraint and minimum rate constraint. The optimization problem is nonconvex because of the fractional objective function and the nonconvex constraints. To deal with the original problem, we firstly convert the objective function in the optimization problem into a difference of two convex functions (D.C.) form, and then propose a NOMA-TDMA-DC algorithm to exploit the global optimum. Numerical results show that the NOMA-TDMA scheme significantly outperforms the traditional orthogonal multiple access scheme in terms of both spectral efficiency and user fairness.

Quantum Optimal Multiple Assignment Scheme for Realizing General Access Structure of Secret Sharing

NASA Astrophysics Data System (ADS)

Matsumoto, Ryutaroh

The multiple assignment scheme is to assign one or more shares to single participant so that any kind of access structure can be realized by classical secret sharing schemes. We propose its quantum version including ramp secret sharing schemes. Then we propose an integer optimization approach to minimize the average share size.

Performance enhancement of optical code-division multiple-access systems using transposed modified Walsh code

NASA Astrophysics Data System (ADS)

Sikder, Somali; Ghosh, Shila

2018-02-01

This paper presents the construction of unipolar transposed modified Walsh code (TMWC) and analysis of its performance in optical code-division multiple-access (OCDMA) systems. Specifically, the signal-to-noise ratio, bit error rate (BER), cardinality, and spectral efficiency were investigated. The theoretical analysis demonstrated that the wavelength-hopping time-spreading system using TMWC was robust against multiple-access interference and more spectrally efficient than systems using other existing OCDMA codes. In particular, the spectral efficiency was calculated to be 1.0370 when TMWC of weight 3 was employed. The BER and eye pattern for the designed TMWC were also successfully obtained using OptiSystem simulation software. The results indicate that the proposed code design is promising for enhancing network capacity.

An access technology delivery protocol for children with severe and multiple disabilities: a case demonstration.

PubMed

Mumford, Leslie; Lam, Rachel; Wright, Virginia; Chau, Tom

2014-08-01

This study applied response efficiency theory to create the Access Technology Delivery Protocol (ATDP), a child and family-centred collaborative approach to the implementation of access technologies. We conducted a descriptive, mixed methods case study to demonstrate the ATDP method with a 12-year-old boy with no reliable means of access to an external device. Evaluations of response efficiency, satisfaction, goal attainment, technology use and participation were made after 8 and 16 weeks of training with a custom smile-based access technology. At the 16 week mark, the new access technology offered better response quality; teacher satisfaction was high; average technology usage was 3-4 times per week for up to 1 h each time; switch sensitivity and specificity reached 78% and 64%, respectively, and participation scores increased by 38%. This case supports further development and testing of the ATDP with additional children with multiple or severe disabilities.

A subjective scheduler for subjective dedicated networks

NASA Astrophysics Data System (ADS)

Suherman; Fakhrizal, Said Reza; Al-Akaidi, Marwan

2017-09-01

Multiple access technique is one of important techniques within medium access layer in TCP/IP protocol stack. Each network technology implements the selected access method. Priority can be implemented in those methods to differentiate services. Some internet networks are dedicated for specific purpose. Education browsing or tutorial video accesses are preferred in a library hotspot, while entertainment and sport contents could be subjects of limitation. Current solution may use IP address filter or access list. This paper proposes subjective properties of users or applications are used for priority determination in multiple access techniques. The NS-2 simulator is employed to evaluate the method. A video surveillance network using WiMAX is chosen as the object. Subjective priority is implemented on WiMAX scheduler based on traffic properties. Three different traffic sources from monitoring video: palace, park, and market are evaluated. The proposed subjective scheduler prioritizes palace monitoring video that results better quality, xx dB than the later monitoring spots.

Barriers to the Accessibility and Continuity of Health-Care Services in People with Multiple Sclerosis

PubMed Central

Bishop, Malachy; Pionke, J.J.; Strauser, David; Santens, Ryan L.

2017-01-01

Background: Individuals with multiple sclerosis (MS) face a range of barriers to accessing and using health-care services. The aim of this review was to identify specific barriers to accessing and using health-care services based on a continuum of the health-care delivery system. Methods: Literature searches were conducted in the PubMed, PsycINFO, CINAHL, and Web of Science databases. The following terms were searched as subject headings, key words, or abstracts: health care, access, barriers, physical disability, and multiple sclerosis. The literature search produced 361 potentially relevant citations. After screening titles, abstracts, and citations, eight citations were selected for full-text review. Results: Health-care barriers were divided into three continuous phases of receiving health care. In the before-visit phase, the most commonly identified barrier was transportation. In the during-visit phase, communication quality was the major concern. In the after-visit phase, discontinued referral was the major barrier encountered. Conclusions: There are multiple interrelated barriers to accessing and using health-care services along the health-care delivery continuum for people with MS and its associated physical disabilities, ranging from complex and long-recognized barriers that will likely require extended advocacy to create policy changes to issues that can and should be addressed through relatively minor changes in health-care delivery practices, improved care coordination, and increased provider awareness, education, and responsiveness to patients' needs. PMID:29270089

System and Method for Detecting Unauthorized Device Access by Comparing Multiple Independent Spatial-Time Data Sets from Other Devices

NASA Technical Reports Server (NTRS)

Westmeyer, Paul A. (Inventor); Wertenberg, Russell F. (Inventor); Krage, Frederick J. (Inventor); Riegel, Jack F. (Inventor)

2017-01-01

An authentication procedure utilizes multiple independent sources of data to determine whether usage of a device, such as a desktop computer, is authorized. When a comparison indicates an anomaly from the base-line usage data, the system, provides a notice that access of the first device is not authorized.

Persons with Multiple Disabilities Use Forehead and Smile Responses to Access or Choose among Technology-Aided Stimulation Events

ERIC Educational Resources Information Center

Lancioni, Giulio E.; Singh, Nirbhay N.; O'Reilly, Mark F.; Sigafoos, Jeff; Alberti, Gloria; Bellini, Domencio; Oliva, Doretta; Boccasini, Adele; La Martire, Maria L.; Signorino, Mario

2013-01-01

A variety of technology-aided programs have been developed to help persons with congenital or acquired multiple disabilities access preferred stimuli or choose among stimulus options. The application of those programs may pose problems when the participants have very limited behavior repertoires and are unable to use conventional responses and…

Multiple Access Interference Reduction Using Received Response Code Sequence for DS-CDMA UWB System

NASA Astrophysics Data System (ADS)

Toh, Keat Beng; Tachikawa, Shin'ichi

This paper proposes a combination of novel Received Response (RR) sequence at the transmitter and a Matched Filter-RAKE (MF-RAKE) combining scheme receiver system for the Direct Sequence-Code Division Multiple Access Ultra Wideband (DS-CDMA UWB) multipath channel model. This paper also demonstrates the effectiveness of the RR sequence in Multiple Access Interference (MAI) reduction for the DS-CDMA UWB system. It suggests that by using conventional binary code sequence such as the M sequence or the Gold sequence, there is a possibility of generating extra MAI in the UWB system. Therefore, it is quite difficult to collect the energy efficiently although the RAKE reception method is applied at the receiver. The main purpose of the proposed system is to overcome the performance degradation for UWB transmission due to the occurrence of MAI during multiple accessing in the DS-CDMA UWB system. The proposed system improves the system performance by improving the RAKE reception performance using the RR sequence which can reduce the MAI effect significantly. Simulation results verify that significant improvement can be obtained by the proposed system in the UWB multipath channel models.

High security chaotic multiple access scheme for visible light communication systems with advanced encryption standard interleaving

NASA Astrophysics Data System (ADS)

Qiu, Junchao; Zhang, Lin; Li, Diyang; Liu, Xingcheng

2016-06-01

Chaotic sequences can be applied to realize multiple user access and improve the system security for a visible light communication (VLC) system. However, since the map patterns of chaotic sequences are usually well known, eavesdroppers can possibly derive the key parameters of chaotic sequences and subsequently retrieve the information. We design an advanced encryption standard (AES) interleaving aided multiple user access scheme to enhance the security of a chaotic code division multiple access-based visible light communication (C-CDMA-VLC) system. We propose to spread the information with chaotic sequences, and then the spread information is interleaved by an AES algorithm and transmitted over VLC channels. Since the computation complexity of performing inverse operations to deinterleave the information is high, the eavesdroppers in a high speed VLC system cannot retrieve the information in real time; thus, the system security will be enhanced. Moreover, we build a mathematical model for the AES-aided VLC system and derive the theoretical information leakage to analyze the system security. The simulations are performed over VLC channels, and the results demonstrate the effectiveness and high security of our presented AES interleaving aided chaotic CDMA-VLC system.

A Review on Spectral Amplitude Coding Optical Code Division Multiple Access

NASA Astrophysics Data System (ADS)

Kaur, Navpreet; Goyal, Rakesh; Rani, Monika

2017-06-01

This manuscript deals with analysis of Spectral Amplitude Coding Optical Code Division Multiple Access (SACOCDMA) system. The major noise source in optical CDMA is co-channel interference from other users known as multiple access interference (MAI). The system performance in terms of bit error rate (BER) degrades as a result of increased MAI. It is perceived that number of users and type of codes used for optical system directly decide the performance of system. MAI can be restricted by efficient designing of optical codes and implementing them with unique architecture to accommodate more number of users. Hence, it is a necessity to design a technique like spectral direct detection (SDD) technique with modified double weight code, which can provide better cardinality and good correlation property.

A satellite mobile communication system based on Band-Limited Quasi-Synchronous Code Division Multiple Access (BLQS-CDMA)

NASA Technical Reports Server (NTRS)

Degaudenzi, R.; Elia, C.; Viola, R.

1990-01-01

Discussed here is a new approach to code division multiple access applied to a mobile system for voice (and data) services based on Band Limited Quasi Synchronous Code Division Multiple Access (BLQS-CDMA). The system requires users to be chip synchronized to reduce the contribution of self-interference and to make use of voice activation in order to increase the satellite power efficiency. In order to achieve spectral efficiency, Nyquist chip pulse shaping is used with no detection performance impairment. The synchronization problems are solved in the forward link by distributing a master code, whereas carrier forced activation and closed loop control techniques have been adopted in the return link. System performance sensitivity to nonlinear amplification and timing/frequency synchronization errors are analyzed.

Multiple Access Schemes for Lunar Missions

NASA Technical Reports Server (NTRS)

Deutsch, Leslie; Hamkins, Jon; Stocklin, Frank J.

2010-01-01

Two years ago, the NASA Coding, Modulation, and Link Protocol (CMLP) study was completed. The study, led by the authors of this paper, recommended codes, modulation schemes, and desired attributes of link protocols for all space communication links in NASA's future space architecture. Portions of the NASA CMLP team were reassembled to resolve one open issue: the use of multiple access (MA) communication from the lunar surface. The CMLP-MA team analyzed and simulated two candidate multiple access schemes that were identified in the original CMLP study: Code Division MA (CDMA) and Frequency Division MA (FDMA) based on a bandwidth-efficient Continuous Phase Modulation (CPM) with a superimposed Pseudo-Noise (PN) ranging signal (CPM/PN). This paper summarizes the results of the analysis and simulation of the CMLP-MA study and describes the final recommendations.

High data rate modem simulation for the space station multiple-access communications system

NASA Technical Reports Server (NTRS)

Horan, Stephen

1987-01-01

The communications system for the space station will require a space based multiple access component to provide communications between the space based program elements and the station. A study was undertaken to investigate two of the concerns of this multiple access system, namely, the issues related to the frequency spectrum utilization and the possibilities for higher order (than QPSK) modulation schemes for use in possible modulators and demodulators (modems). As a result of the investigation, many key questions about the frequency spectrum utilization were raised. At this point, frequency spectrum utilization is seen as an area requiring further work. Simulations were conducted using a computer aided communications system design package to provide a straw man modem structure to be used for both QPSK and 8-PSK channels.

Multiple Intimate Partner Violence Experiences: Knowledge, Access, Utilization and Barriers to Utilization of Resources by Women of the African Diaspora

PubMed Central

Sabri, Bushra; Huerta, Julia; Alexander, Kamila A.; St.Vil, Noelle M.; Campbell, Jacquelyn C.; Callwood, Gloria B.

2016-01-01

Objective This study examined knowledge, access, utilization, and barriers to use of resources among Black women exposed to multiple types of intimate partner violence in Baltimore, Maryland and the U.S. Virgin Islands (USVI). Methods We analyzed quantitative survey data collected by 163 women recruited from primary care, prenatal or family planning clinics in Baltimore and the USVI. In addition we analyzed qualitative data from in-depth interviews with 11 women. Quantitative data were analyzed using descriptive statistics and qualitative data were analyzed using thematic analysis. Results A substantial proportion of Black women with multiple types of violence experiences lacked knowledge of, did not have access to, and did not use resources. Barriers to resource use were identified at the individual, relationship, and community levels. Conclusion There is need for programs to develop awareness, promote access and utilization of resources, and eliminate barriers to resource use among abused Black women. PMID:26548679

Metro-access integrated network based on optical OFDMA with dynamic sub-carrier allocation and power distribution.

PubMed

Zhang, Chongfu; Zhang, Qiongli; Chen, Chen; Jiang, Ning; Liu, Deming; Qiu, Kun; Liu, Shuang; Wu, Baojian

2013-01-28

We propose and demonstrate a novel optical orthogonal frequency-division multiple access (OFDMA)-based metro-access integrated network with dynamic resource allocation. It consists of a single fiber OFDMA ring and many single fiber OFDMA trees, which transparently integrates metropolitan area networks with optical access networks. The single fiber OFDMA ring connects the core network and the central nodes (CNs), the CNs are on demand reconfigurable and use multiple orthogonal sub-carriers to realize parallel data transmission and dynamic resource allocation, meanwhile, they can also implement flexible power distribution. The remote nodes (RNs) distributed in the user side are connected by the single fiber OFDMA trees with the corresponding CN. The obtained results indicate that our proposed metro-access integrated network is feasible and the power distribution is agile.

Adaptive Transmission and Channel Modeling for Frequency Hopping Communications

DTIC Science & Technology

2009-09-21

proposed adaptive transmission method has much greater system capacity than conventional non-adaptive MC direct- sequence ( DS )- CDMA system. • We...several mobile radio systems. First, a new improved allocation algorithm was proposed for multicarrier code-division multiple access (MC- CDMA ) system...Multicarrier code-division multiple access (MC- CDMA ) system with adaptive frequency hopping (AFH) has attracted attention of researchers due to its

Next generation communications satellites: Multiple access and network studies

NASA Technical Reports Server (NTRS)

Stern, T. E.; Schwartz, M.; Meadows, H. E.; Ahmadi, H. K.; Gadre, J. G.; Gopal, I. S.; Matsmo, K.

1980-01-01

Following an overview of issues involved in the choice of promising system architectures for efficient communication with multiple small inexpensive Earth stations serving hetergeneous user populations, performance evaluation via analysis and simulation for six SS/TDMA (satellite-switched/time-division multiple access) system architectures is discussed. These configurations are chosen to exemplify the essential alternatives available in system design. Although the performance evaluation analyses are of fairly general applicability, whenever possible they are considered in the context of NASA's 30/20 GHz studies. Packet switched systems are considered, with the assumption that only a part of transponder capacit is devoted to packets, the integration of circuit and packet switched traffic being reserved for further study. Three types of station access are distinguished: fixed (FA), demand (DA), and random access (RA). Similarly, switching in the satellite can be assigned on a fixed (FS) or demand (DS) basis, or replaced by a buffered store-and-forward system (SF) onboard the satellite. Since not all access/switching combinations are practical, six systems are analyzed in detail: three FS SYSTEMS, FA/FS, DA/ES, RA/FS; one DS system, DA/DS; and two SF systems, FA/SF, DA/SF. Results are presented primarily in terms of delay-throughput characteristics.

Distributed magnetic field positioning system using code division multiple access

NASA Technical Reports Server (NTRS)

Prigge, Eric A. (Inventor)

2003-01-01

An apparatus and methods for a magnetic field positioning system use a fundamentally different, and advantageous, signal structure and multiple access method, known as Code Division Multiple Access (CDMA). This signal architecture, when combined with processing methods, leads to advantages over the existing technologies, especially when applied to a system with a large number of magnetic field generators (beacons). Beacons at known positions generate coded magnetic fields, and a magnetic sensor measures a sum field and decomposes it into component fields to determine the sensor position and orientation. The apparatus and methods can have a large `building-sized` coverage area. The system allows for numerous beacons to be distributed throughout an area at a number of different locations. A method to estimate position and attitude, with no prior knowledge, uses dipole fields produced by these beacons in different locations.

Feedback power control strategies in wireless sensor networks with joint channel decoding.

PubMed

Abrardo, Andrea; Ferrari, Gianluigi; Martalò, Marco; Perna, Fabio

2009-01-01

In this paper, we derive feedback power control strategies for block-faded multiple access schemes with correlated sources and joint channel decoding (JCD). In particular, upon the derivation of the feasible signal-to-noise ratio (SNR) region for the considered multiple access schemes, i.e., the multidimensional SNR region where error-free communications are, in principle, possible, two feedback power control strategies are proposed: (i) a classical feedback power control strategy, which aims at equalizing all link SNRs at the access point (AP), and (ii) an innovative optimized feedback power control strategy, which tries to make the network operational point fall in the feasible SNR region at the lowest overall transmit energy consumption. These strategies will be referred to as "balanced SNR" and "unbalanced SNR," respectively. While they require, in principle, an unlimited power control range at the sources, we also propose practical versions with a limited power control range. We preliminary consider a scenario with orthogonal links and ideal feedback. Then, we analyze the robustness of the proposed power control strategies to possible non-idealities, in terms of residual multiple access interference and noisy feedback channels. Finally, we successfully apply the proposed feedback power control strategies to a limiting case of the class of considered multiple access schemes, namely a central estimating officer (CEO) scenario, where the sensors observe noisy versions of a common binary information sequence and the AP's goal is to estimate this sequence by properly fusing the soft-output information output by the JCD algorithm.

Lexical access changes in patients with multiple sclerosis: a two-year follow-up study.

PubMed

Sepulcre, Jorge; Peraita, Herminia; Goni, Joaquin; Arrondo, Gonzalo; Martincorena, Inigo; Duque, Beatriz; Velez de Mendizabal, Nieves; Masdeu, Joseph C; Villoslada, Pablo

2011-02-01

The aim of the study was to analyze lexical access strategies in patients with multiple sclerosis (MS) and their changes over time. We studied lexical access strategies during semantic and phonemic verbal fluency tests and also confrontation naming in a 2-year prospective cohort of 45 MS patients and 20 healthy controls. At baseline, switching lexical access strategy (both in semantic and in phonemic verbal fluency tests) and confrontation naming were significantly impaired in MS patients compared with controls. After 2 years follow-up, switching score decreased, and cluster size increased over time in semantic verbal fluency tasks, suggesting a failure in the retrieval of lexical information rather than an impairment of the lexical pool. In conclusion, these findings underline the significant presence of lexical access problems in patients with MS and could point out their key role in the alterations of high-level communications abilities in MS.

Space-Time Processing for Tactical Mobile Ad Hoc Networks

DTIC Science & Technology

2010-05-01

Spatial Diversity and Imperfect Channel Estimation on Wideband MC- DS - CDMA and MC- CDMA " IEEE Transactions on Communications, Vol. 57, No. 10, pp. 2988...include direct sequence code division multiple access ( DS - CDMA ), Frequency Hopped (FH) CDMA and Orthogonal Frequency Division Multiple Access (OFDMA...capability, LPD/LPI, and operability in non-continuous spectrum. In addition, FH- CDMA is robust to the near-far problem, while DS - CDMA requires

ABSENTEE COMPUTATIONS IN A MULTIPLE-ACCESS COMPUTER SYSTEM.

DTIC Science & Technology

require user interaction, and the user may therefore want to run these computations ’ absentee ’ (or, user not present). A mechanism is presented which...provides for the handling of absentee computations in a multiple-access computer system. The design is intended to be implementation-independent...Some novel features of the system’s design are: a user can switch computations from interactive to absentee (and vice versa), the system can

Parallel Object Activation and Attentional Gating of Information: Evidence from Eye Movements in the Multiple Object Naming Paradigm

ERIC Educational Resources Information Center

Schotter, Elizabeth R.; Ferreira, Victor S.; Rayner, Keith

2013-01-01

Do we access information from any object we can see, or do we access information only from objects that we intend to name? In 3 experiments using a modified multiple object naming paradigm, subjects were required to name several objects in succession when previews appeared briefly and simultaneously in the same location as the target as well as at…

Reduced representation approaches to interrogate genome diversity in large repetitive plant genomes.

PubMed

Hirsch, Cory D; Evans, Joseph; Buell, C Robin; Hirsch, Candice N

2014-07-01

Technology and software improvements in the last decade now provide methodologies to access the genome sequence of not only a single accession, but also multiple accessions of plant species. This provides a means to interrogate species diversity at the genome level. Ample diversity among accessions in a collection of species can be found, including single-nucleotide polymorphisms, insertions and deletions, copy number variation and presence/absence variation. For species with small, non-repetitive rich genomes, re-sequencing of query accessions is robust, highly informative, and economically feasible. However, for species with moderate to large sized repetitive-rich genomes, technical and economic barriers prevent en masse genome re-sequencing of accessions. Multiple approaches to access a focused subset of loci in species with larger genomes have been developed, including reduced representation sequencing, exome capture and transcriptome sequencing. Collectively, these approaches have enabled interrogation of diversity on a genome scale for large plant genomes, including crop species important to worldwide food security. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Multiple-access phased array antenna simulator for a digital beam-forming system investigation

NASA Technical Reports Server (NTRS)

Kerczewski, Robert J.; Yu, John; Walton, Joanne C.; Perl, Thomas D.; Andro, Monty; Alexovich, Robert E.

1992-01-01

Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beamforming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise, and nonlinearities.

Multiple-access phased array antenna simulator for a digital beam forming system investigation

NASA Technical Reports Server (NTRS)

Kerczewski, Robert J.; Yu, John; Walton, Joanne C.; Perl, Thomas D.; Andro, Monty; Alexovich, Robert E.

1992-01-01

Future versions of data relay satellite systems are currently being planned by NASA. Being given consideration for implementation are on-board digital beamforming techniques which will allow multiple users to simultaneously access a single S-band phased array antenna system. To investigate the potential performance of such a system, a laboratory simulator has been developed at NASA's Lewis Research Center. This paper describes the system simulator, and in particular, the requirements, design, and performance of a key subsystem, the phased array antenna simulator, which provides realistic inputs to the digital processor including multiple signals, noise, and nonlinearities.

Structure for common access and support of fuel cell stacks

DOEpatents

Walsh, Michael M.

2000-01-01

A structure provides common support and access to multiple fuel cells externally mounted thereto. The structure has openings leading to passages defined therein for providing the access. Various other fuel cell power system components are connected at the openings, such as reactant and coolant sources.

Teaching Individuals with Profound Multiple Disabilities to Access Preferred Stimuli with Multiple Microswitches

ERIC Educational Resources Information Center

Tam, Gee May; Phillips, Katrina J.; Mudford, Oliver C.

2011-01-01

We replicated and extended previous research on microswitch facilitated choice making by individuals with profound multiple disabilities. Following an assessment of stimulus preferences, we taught 6 adults with profound multiple disabilities to emit 2 different responses to activate highly preferred stimuli. All participants learnt to activate…

Beam Design and User Scheduling for Nonorthogonal Multiple Access With Multiple Antennas Based on Pareto Optimality

NASA Astrophysics Data System (ADS)

Seo, Junyeong; Sung, Youngchul

2018-06-01

In this paper, an efficient transmit beam design and user scheduling method is proposed for multi-user (MU) multiple-input single-output (MISO) non-orthogonal multiple access (NOMA) downlink, based on Pareto-optimality. The proposed beam design and user scheduling method groups simultaneously-served users into multiple clusters with practical two users in each cluster, and then applies spatical zeroforcing (ZF) across clusters to control inter-cluster interference (ICI) and Pareto-optimal beam design with successive interference cancellation (SIC) to two users in each cluster to remove interference to strong users and leverage signal-to-interference-plus-noise ratios (SINRs) of interference-experiencing weak users. The proposed method has flexibility to control the rates of strong and weak users and numerical results show that the proposed method yields good performance.

A DTN-Based Multiple Access Fast Forward Service for the NASA Space Network

NASA Technical Reports Server (NTRS)

Israel, David; Davis, Faith; Marquart. Jane

2011-01-01

The NASA Space Network provides a demand access return link service capable of providing users a space link "on demand". An equivalent service in the forward link direction is not possible due to Tracking and Data Relay Spacecraft (TDRS) constraints. A Disruption Tolerant Networking (DTN)-based Multiple Access Fast Forward (MAFF) service has been proposed to provide a forward link to a user as soon as possible. Previous concept studies have identified a basic architecture and implementation approach. This paper reviews the user scenarios and benefits of an MAFF service and proposes an implementation approach based on the use of DTN protocols.

Case Study in Modeling Accessibility for Online Instruction

ERIC Educational Resources Information Center

Conway, Thomas Hayes

2017-01-01

The purpose of this qualitative multiple case study was to explore how accessibility standards are adapted to create online learning environments that are accessible to people who use assistive technology, or have navigational challenges due to physical or intellectual disabilities. Rogers diffusion of innovation was used as the contextual…

Identity and Access Management: Technological Implementation of Policy

ERIC Educational Resources Information Center

von Munkwitz-Smith, Jeff; West, Ann

2004-01-01

Navigating the multiple processes for accessing ever-multiplying campus information systems can be a daunting task for students, faculty, and staff. This article provides a brief overview of Identity and Access Management Services. The authors review key characteristics and components of this new information architecture and address the issue of…

Study of optoelectronic switch for satellite-switched time-division multiple access

NASA Technical Reports Server (NTRS)

Su, Shing-Fong; Jou, Liz; Lenart, Joe

1987-01-01

The use of optoelectronic switching for satellite switched time division multiple access will improve the isolation and reduce the crosstalk of an IF switch matrix. The results are presented of a study on optoelectronic switching. Tasks include literature search, system requirements study, candidate switching architecture analysis, and switch model optimization. The results show that the power divided and crossbar switching architectures are good candidates for an IF switch matrix.

MCNP6 Fission Multiplicity with FMULT Card

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilcox, Trevor; Fensin, Michael Lorne; Hendricks, John S.

With the merger of MCNPX and MCNP5 into MCNP6, MCNP6 now provides all the capabilities of both codes allowing the user to access all the fission multiplicity data sets. Detailed in this paper is: (1) the new FMULT card capabilities for accessing these different data sets; (2) benchmark calculations, as compared to experiment, detailing the results of selecting these separate data sets for thermal neutron induced fission on U-235.

Maritime Analytics Prototype: Final Development Report

DTIC Science & Technology

2014-04-01

access management platform OpenAM , support for multiple instances of the same type of widget and support for installation specific configuration files to...et de la gestion de l’accès OpenAM , le support pour plusieurs instances du même type de widget et le support des fichiers d’installation de...open source authentication and access management platform OpenAM , support for multiple instances of the same type of widget and support for

Coherent direct sequence optical code multiple access encoding-decoding efficiency versus wavelength detuning.

PubMed

Pastor, D; Amaya, W; García-Olcina, R; Sales, S

2007-07-01

We present a simple theoretical model of and the experimental verification for vanishing of the autocorrelation peak due to wavelength detuning on the coding-decoding process of coherent direct sequence optical code multiple access systems based on a superstructured fiber Bragg grating. Moreover, the detuning vanishing effect has been explored to take advantage of this effect and to provide an additional degree of multiplexing and/or optical code tuning.

On the performance of a code division multiple access scheme with transmit/receive conflicts

NASA Astrophysics Data System (ADS)

Silvester, J. A.

One of the benefits of spread spectrum is that by assigning each user a different orthogonal signal set, multiple transmissions can occur simultaneously. This possibility is utilized in new access schemes called Code Division Multiple Access (CDMA). The present investigation is concerned with a particular CDMA implementation in which the transmit times for each symbol are exactly determined in a distributed manner such that both sender and receiver know them. In connection with a decision whether to transmit or receive, the loss of a symbol in one of the channels results. The system employs thus a coding technique which permits correct decoding of a codeword even if some constituent symbols are missing or in error. The technique used is Reed Solomon coding. The performance of this system is analyzed, and attention is given to the optimum strategy which should be used in deciding whether to receive or transmit.

Heuristic query optimization for query multiple table and multiple clausa on mobile finance application

NASA Astrophysics Data System (ADS)

Indrayana, I. N. E.; P, N. M. Wirasyanti D.; Sudiartha, I. KG

2018-01-01

Mobile application allow many users to access data from the application without being limited to space, space and time. Over time the data population of this application will increase. Data access time will cause problems if the data record has reached tens of thousands to millions of records.The objective of this research is to maintain the performance of data execution for large data records. One effort to maintain data access time performance is to apply query optimization method. The optimization used in this research is query heuristic optimization method. The built application is a mobile-based financial application using MySQL database with stored procedure therein. This application is used by more than one business entity in one database, thus enabling rapid data growth. In this stored procedure there is an optimized query using heuristic method. Query optimization is performed on a “Select” query that involves more than one table with multiple clausa. Evaluation is done by calculating the average access time using optimized and unoptimized queries. Access time calculation is also performed on the increase of population data in the database. The evaluation results shown the time of data execution with query heuristic optimization relatively faster than data execution time without using query optimization.

Feedback Power Control Strategies in Wireless Sensor Networks with Joint Channel Decoding

PubMed Central

Abrardo, Andrea; Ferrari, Gianluigi; Martalò, Marco; Perna, Fabio

2009-01-01

In this paper, we derive feedback power control strategies for block-faded multiple access schemes with correlated sources and joint channel decoding (JCD). In particular, upon the derivation of the feasible signal-to-noise ratio (SNR) region for the considered multiple access schemes, i.e., the multidimensional SNR region where error-free communications are, in principle, possible, two feedback power control strategies are proposed: (i) a classical feedback power control strategy, which aims at equalizing all link SNRs at the access point (AP), and (ii) an innovative optimized feedback power control strategy, which tries to make the network operational point fall in the feasible SNR region at the lowest overall transmit energy consumption. These strategies will be referred to as “balanced SNR” and “unbalanced SNR,” respectively. While they require, in principle, an unlimited power control range at the sources, we also propose practical versions with a limited power control range. We preliminary consider a scenario with orthogonal links and ideal feedback. Then, we analyze the robustness of the proposed power control strategies to possible non-idealities, in terms of residual multiple access interference and noisy feedback channels. Finally, we successfully apply the proposed feedback power control strategies to a limiting case of the class of considered multiple access schemes, namely a central estimating officer (CEO) scenario, where the sensors observe noisy versions of a common binary information sequence and the AP's goal is to estimate this sequence by properly fusing the soft-output information output by the JCD algorithm. PMID:22291536

TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

USGS Publications Warehouse

Song, W.-Z.; Huang, R.; Shirazi, B.; Husent, R.L.

2009-01-01

Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and frame into slots. Parent determines children's frame assigmnent based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. Firstly, given any node, at any time slot, there is at most one active sender in its neighborhood (includ ing itself). Secondly, the packet scheduling with TreelMAC is bufferless, which therefore minimizes the probability of network congestion. Thirdly, the data throughput to gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24 node test bed demonstrate that TreeMAC protocol significantly improves network throughput and energy efficiency, by comparing to the TinyOS's default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC[8]. ?? 2009 IEEE.

Fourth Annual International Acquisitions Workshop: Access to Multiple Media Worldwide

NASA Technical Reports Server (NTRS)

1994-01-01

Topics discussed during the workshop include: (1) Multinational-Multiple media collections and activities spanning many countries; (2) Multiple media in North American trade and commerce; (3) African spotlight; (4) Europe-Multiple media in national libraries and services; (5) Scandinavian spotlight; (6) Internet update; (7) Multiple media in US federal agencies; (8) Open-source multiple media in US federal agencies; and (9) Multiple media at US federal technical agencies-NIST and NOAA.

Evaluation of Renal Function after Percutaneous Nephrolithotomy-Does the Number of Percutaneous Access Tracts Matter?

PubMed

Gorbachinsky, Ilya; Wood, Kyle; Colaco, Marc; Hemal, Sij; Mettu, Jayadev; Mirzazadeh, Majid; Assimos, Dean G; Gutierrez-Aćeves, Jorge

2016-07-01

Renal function following percutaneous nephrolithotomy has long been a concern to urologists, especially in the setting of multi-tract access. We determined whether the risk of renal injury after multi-tract percutaneous nephrolithotomy was greater than after a single access approach. We retrospectively reviewed the records of 307 consecutive patients treated with percutaneous nephrolithotomy from 2011 to 2012 at Wake Forest Health. Perioperative (99m)Tc-mercaptoacetyltriglycine nuclear renogram parameters along with serum creatinine values were assessed within 1 year of the procedure. Patients were stratified by single access vs multi-access (2 or more). We identified 110 cases in which renography was done before and after percutaneous nephrolithotomy. A total of 74 patients (67.3%) underwent single access percutaneous nephrolithotomy while 36 (32.7%) underwent multi-access percutaneous nephrolithotomy. Serum creatinine did not significantly differ between the 2 cohorts postoperatively (p = 0.09). There was a significant 2.28% decrease in renal function based on mercaptoacetyltriglycine nuclear renogram results after percutaneous nephrolithotomy of the affected kidney in patients with multiple accesses (p <0.01). This relationship was not observed when patients were stratified by multiple comorbidities associated with nephrolithiasis. Multi-access percutaneous nephrolithotomy is associated with a small reduction in the function of the targeted kidney compared to a single access approach. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Securely and Flexibly Sharing a Biomedical Data Management System

PubMed Central

Wang, Fusheng; Hussels, Phillip; Liu, Peiya

2011-01-01

Biomedical database systems need not only to address the issues of managing complex data, but also to provide data security and access control to the system. These include not only system level security, but also instance level access control such as access of documents, schemas, or aggregation of information. The latter is becoming more important as multiple users can share a single scientific data management system to conduct their research, while data have to be protected before they are published or IP-protected. This problem is challenging as users’ needs for data security vary dramatically from one application to another, in terms of who to share with, what resources to be shared, and at what access level. We develop a comprehensive data access framework for a biomedical data management system SciPort. SciPort provides fine-grained multi-level space based access control of resources at not only object level (documents and schemas), but also space level (resources set aggregated in a hierarchy way). Furthermore, to simplify the management of users and privileges, customizable role-based user model is developed. The access control is implemented efficiently by integrating access privileges into the backend XML database, thus efficient queries are supported. The secure access approach we take makes it possible for multiple users to share the same biomedical data management system with flexible access management and high data security. PMID:21625285

Accessing and visualizing scientific spatiotemporal data

NASA Technical Reports Server (NTRS)

Katz, Daniel S.; Bergou, Attila; Berriman, G. Bruce; Block, Gary L.; Collier, Jim; Curkendall, David W.; Good, John; Husman, Laura; Jacob, Joseph C.; Laity, Anastasia;

Broadband Time Division Multiple Access (TDMA) Solution (Tech Insertion - C4 Enhancement for the U.S. Army in Transformation)

DTIC Science & Technology

2005-06-01

synchronization , timing and frequency to all of the traffic terminals through the reference burst. The MRT also periodically synchronizes all of the traffic...1 2005 Command and Control Research and Technology Symposium The Future of C2 Broadband Time Division Multiple Access (TDMA) Solution...UK Army) Dale White Barry Kruse Shawn White LTC Edward Eidson Thomas Mims COL Charles Dunn III Charlie Pangle Battle Command Battle

Combining data from multiple sources using the CUAHSI Hydrologic Information System

NASA Astrophysics Data System (ADS)

Tarboton, D. G.; Ames, D. P.; Horsburgh, J. S.; Goodall, J. L.

2012-12-01

The Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI) has developed a Hydrologic Information System (HIS) to provide better access to data by enabling the publication, cataloging, discovery, retrieval, and analysis of hydrologic data using web services. The CUAHSI HIS is an Internet based system comprised of hydrologic databases and servers connected through web services as well as software for data publication, discovery and access. The HIS metadata catalog lists close to 100 web services registered to provide data through this system, ranging from large federal agency data sets to experimental watersheds managed by University investigators. The system's flexibility in storing and enabling public access to similarly formatted data and metadata has created a community data resource from governmental and academic data that might otherwise remain private or analyzed only in isolation. Comprehensive understanding of hydrology requires integration of this information from multiple sources. HydroDesktop is the client application developed as part of HIS to support data discovery and access through this system. HydroDesktop is founded on an open source GIS client and has a plug-in architecture that has enabled the integration of modeling and analysis capability with the functionality for data discovery and access. Model integration is possible through a plug-in built on the OpenMI standard and data visualization and analysis is supported by an R plug-in. This presentation will demonstrate HydroDesktop, showing how it provides an analysis environment within which data from multiple sources can be discovered, accessed and integrated.

Latin American algorithm for treatment of relapsing-remitting multiple sclerosis using disease-modifying agents.

PubMed

Finkelsztejn, Alessandro; Gabbai, Alberto Alain; Fragoso, Yara Dadalti; Carrá, Adriana; Macías-Islas, Miguel Angel; Arcega-Revilla, Raul; García-Bonitto, Juan; Oehninger-Gatti, Carlos Luis; Orozco-Escobar, Geraldine; Tarulla, Adriana; Vergara, Fernando; Vizcarra, Darwin

2012-10-01

It is estimated that circa 50,000 individuals have relapsing-remitting multiple sclerosis in Latin America. European and North-American algorithms for the treatment of multiple sclerosis do not foresee our regional difficulties and the access of patients to treatment. The Latin American Multiple Sclerosis Forum is an independent and supra-institutional group of experts that has assessed the latest scientific evidence regarding efficacy and safety of disease-modifying treatments. Accesses to treatment and pharmacovigilance programs for each of the eight countries represented at the Forum were also analyzed. A specific set of guidelines based upon evidence-based recommendations was designed for Latin America. Future perspectives of multiple sclerosis treatment were also discussed. The present paper translated an effort from representatives of eight countries discussing a matter that cannot be adapted to our region directly from purely European and North-American guidelines for treatment.

Virtual Computing Laboratories: A Case Study with Comparisons to Physical Computing Laboratories

ERIC Educational Resources Information Center

Burd, Stephen D.; Seazzu, Alessandro F.; Conway, Christopher

2009-01-01

Current technology enables schools to provide remote or virtual computing labs that can be implemented in multiple ways ranging from remote access to banks of dedicated workstations to sophisticated access to large-scale servers hosting virtualized workstations. This paper reports on the implementation of a specific lab using remote access to…

The introduction and evaluation of mobile devices to improve access to patient records: a catalyst for innovation and collaboration at BCCA.

PubMed

Wu, Jonn; Waldron, John; Hood, Shaina; Kahnamelli, Adam; Khan, Mohamed; Barnett, Jeff; French, John; Slager, Stacey; Melhem, Shadi; Shabestari, Omid

2013-01-01

Prompt and efficient access to patient records is vital in providing optimal patient care. The Cancer Agency Information System (CAIS) is the primary patient record repository for the British Columbia Cancer Agency (BCCA) but is only accessible on traditional computer workstations. The BCCA clinics have significant space limitations resulting in multiple health care professionals sharing each workstation. Furthermore, workstations are not available in examination rooms. A novel and cost efficient solution is necessary to improve clinician access to CAIS. This prompted the BCCA and IMITS to embark on an innovative provincial collaboration to introduce and evaluate the impact of a mobile device to improve access to CAIS. The project consisted of 2 phases with over 50 participants from multiple clinical disciplines across BCCA sites. Phase I evaluated the adoptability, effectiveness and costs associated with providing access to CAIS using a generic viewer (Citrix). Phase II incorporated the feedback and findings from Phase I to make available a customized mobile device-specific application. Phase II also addressed privacy and security requirements.

Research on a Queue Scheduling Algorithm in Wireless Communications Network

NASA Astrophysics Data System (ADS)

Yang, Wenchuan; Hu, Yuanmei; Zhou, Qiancai

This paper proposes a protocol QS-CT, Queue Scheduling Mechanism based on Multiple Access in Ad hoc net work, which adds queue scheduling mechanism to RTS-CTS-DATA using multiple access protocol. By endowing different queues different scheduling mechanisms, it makes networks access to the channel much more fairly and effectively, and greatly enhances the performance. In order to observe the final performance of the network with QS-CT protocol, we simulate it and compare it with MACA/C-T without QS-CT protocol. Contrast to MACA/C-T, the simulation result shows that QS-CT has greatly improved the throughput, delay, rate of packets' loss and other key indicators.

Performance evaluation of modulation and multiple access schemes in ultraviolet optical wireless connections for two atmosphere thickness cases.

PubMed

Raptis, Nikos; Pikasis, Evangelos; Syvridis, Dimitris

2016-08-01

The exploitation of optical wireless communication channels in a non-line-of-sight regime is studied for point-to-point and networking configurations considering the use of light-emitting diodes. Two environments with different scattering center densities are considered, assuming operation at 265 nm. The bit error rate performance of both pulsed and multicarrier modulation schemes is examined, using numerical approaches. In the networking scenario, a central node only receives data, one node transmits useful data, and the rest of them act as interferers. The performance of the desirable node's transmissions is evaluated. The access to the medium is controlled by a code division multiple access scheme.

Apollo: Giving application developers a single point of access to public health models using structured vocabularies and Web services

PubMed Central

Wagner, Michael M.; Levander, John D.; Brown, Shawn; Hogan, William R.; Millett, Nicholas; Hanna, Josh

2013-01-01

This paper describes the Apollo Web Services and Apollo-SV, its related ontology. The Apollo Web Services give an end-user application a single point of access to multiple epidemic simulators. An end user can specify an analytic problem—which we define as a configuration and a query of results—exactly once and submit it to multiple epidemic simulators. The end user represents the analytic problem using a standard syntax and vocabulary, not the native languages of the simulators. We have demonstrated the feasibility of this design by implementing a set of Apollo services that provide access to two epidemic simulators and two visualizer services. PMID:24551417

Apollo: giving application developers a single point of access to public health models using structured vocabularies and Web services.

PubMed

Wagner, Michael M; Levander, John D; Brown, Shawn; Hogan, William R; Millett, Nicholas; Hanna, Josh

2013-01-01

This paper describes the Apollo Web Services and Apollo-SV, its related ontology. The Apollo Web Services give an end-user application a single point of access to multiple epidemic simulators. An end user can specify an analytic problem-which we define as a configuration and a query of results-exactly once and submit it to multiple epidemic simulators. The end user represents the analytic problem using a standard syntax and vocabulary, not the native languages of the simulators. We have demonstrated the feasibility of this design by implementing a set of Apollo services that provide access to two epidemic simulators and two visualizer services.

Web service activities at the IRIS DMC to support federated and multidisciplinary access

NASA Astrophysics Data System (ADS)

Trabant, Chad; Ahern, Timothy K.

2013-04-01

At the IRIS Data Management Center (DMC) we have developed a suite of web service interfaces to access our large archive of, primarily seismological, time series data and related metadata. The goals of these web services include providing: a) next-generation and easily used access interfaces for our current users, b) access to data holdings in a form usable for non-seismologists, c) programmatic access to facilitate integration into data processing workflows and d) a foundation for participation in federated data discovery and access systems. To support our current users, our services provide access to the raw time series data and metadata or conversions of the raw data to commonly used formats. Our services also support simple, on-the-fly signal processing options that are common first steps in many workflows. Additionally, high-level data products derived from raw data are available via service interfaces. To support data access by researchers unfamiliar with seismic data we offer conversion of the data to broadly usable formats (e.g. ASCII text) and data processing to convert the data to Earth units. By their very nature, web services are programmatic interfaces. Combined with ubiquitous support for web technologies in programming & scripting languages and support in many computing environments, web services are very well suited for integrating data access into data processing workflows. As programmatic interfaces that can return data in both discipline-specific and broadly usable formats, our services are also well suited for participation in federated and brokered systems either specific to seismology or multidisciplinary. Working within the International Federation of Digital Seismograph Networks, the DMC collaborated on the specification of standardized web service interfaces for use at any seismological data center. These data access interfaces, when supported by multiple data centers, will form a foundation on which to build discovery and access mechanisms for data sets spanning multiple centers. To promote the adoption of these standardized services the DMC has developed portable implementations of the software needed to host these interfaces, minimizing the work required at each data center. Within the COOPEUS project framework, the DMC is working with EU partners to install web services implementations at multiple data centers in Europe.

Network accessibility & the evoluation of urban employment.

DOT National Transportation Integrated Search

2011-06-01

This research examines the impact of accessibility on the growth of employment centers in the : Los Angeles Region between 1980 and 2000. There is extensive empirical documentation of : polycentricity the presence of multiple concentrations of em...

A physical layer perspective on access network sharing

NASA Astrophysics Data System (ADS)

Pfeiffer, Thomas

2015-12-01

Unlike in copper or wireless networks, there is no sharing of resources in fiber access networks yet, other than bit stream access or cable sharing, in which the fibers of a cable are let to one or multiple operators. Sharing optical resources on a single fiber among multiple operators or different services has not yet been applied. While this would allow for a better exploitation of installed infrastructures, there are operational issues which still need to be resolved, before this sharing model can be implemented in networks. Operating multiple optical systems and services over a common fiber plant, autonomously and independently from each other, can result in mutual distortions on the physical layer. These distortions will degrade the performance of the involved systems, unless precautions are taken in the infrastructure hardware to eliminate or to reduce them to an acceptable level. Moreover, the infrastructure needs to be designed such as to support different system technologies and to ensure a guaranteed quality of the end-to-end connections. In this paper, suitable means are proposed to be introduced in fiber access infrastructures that will allow for shared utilization of the fibers while safeguarding the operational needs and business interests of the involved parties.

What versus where: Investigating how autobiographical memory retrieval differs when accessed with thematic versus spatial information.

PubMed

Sheldon, Signy; Chu, Sonja

2017-09-01

Autobiographical memory research has investigated how cueing distinct aspects of a past event can trigger different recollective experiences. This research has stimulated theories about how autobiographical knowledge is accessed and organized. Here, we test the idea that thematic information organizes multiple autobiographical events whereas spatial information organizes individual past episodes by investigating how retrieval guided by these two forms of information differs. We used a novel autobiographical fluency task in which participants accessed multiple memory exemplars to event theme and spatial (location) cues followed by a narrative description task in which they described the memories generated to these cues. Participants recalled significantly more memory exemplars to event theme than to spatial cues; however, spatial cues prompted faster access to past memories. Results from the narrative description task revealed that memories retrieved via event theme cues compared to spatial cues had a higher number of overall details, but those recalled to the spatial cues were recollected with a greater concentration on episodic details than those retrieved via event theme cues. These results provide evidence that thematic information organizes and integrates multiple memories whereas spatial information prompts the retrieval of specific episodic content from a past event.

Nonadditivity of quantum and classical capacities for entanglement breaking multiple-access channels and the butterfly network

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grudka, Andrzej; National Quantum Information Centre of Gdansk, PL-81-824 Sopot; Horodecki, Pawel

2010-06-15

We analyze quantum network primitives which are entanglement breaking. We show superadditivity of quantum and classical capacity regions for quantum multiple-access channels and the quantum butterfly network. Since the effects are especially visible at high noise they suggest that quantum information effects may be particularly helpful in the case of the networks with occasional high noise rates. The present effects provide a qualitative borderline between superadditivities of bipartite and multipartite systems.

Code division multiple access signaling for modulated reflector technology

DOEpatents

Briles, Scott D [Los Alamos, NM

2012-05-01

A method and apparatus for utilizing code division multiple access in modulated reflectance transmissions comprises the steps of generating a phase-modulated reflectance data bit stream; modifying the modulated reflectance data bit stream; providing the modified modulated reflectance data bit stream to a switch that connects an antenna to an infinite impedance in the event a "+1" is to be sent, or connects the antenna to ground in the event a "0" or a "-1" is to be sent.

System Design and Cataloging Meet the User: User Interfaces to Online Public Access Catalogs.

ERIC Educational Resources Information Center

Yee, Martha M.

1991-01-01

Discusses features of online public access catalogs: (1) demonstration of relationships between records; (2) provision of entry vocabularies; (3) arrangement of multiple entries on the screen; (4) provision of access points; (5) display of single records; and (6) division of catalogs into separate files or indexes. User studies and other research…

Action Research to Improve Methods of Delivery and Feedback in an Access Grid Room Environment

ERIC Educational Resources Information Center

McArthur, Lynne C.; Klass, Lara; Eberhard, Andrew; Stacey, Andrew

2011-01-01

This article describes a qualitative study which was undertaken to improve the delivery methods and feedback opportunity in honours mathematics lectures which are delivered through Access Grid Rooms. Access Grid Rooms are facilities that provide two-way video and audio interactivity across multiple sites, with the inclusion of smart boards. The…

Improving Global Access to New Vaccines: Intellectual Property, Technology Transfer, and Regulatory Pathways

PubMed Central

2014-01-01

The 2012 World Health Assembly Global Vaccine Action Plan called for global access to new vaccines within 5 years of licensure. Current approaches have proven insufficient to achieve sustainable vaccine pricing within such a timeline. Paralleling the successful strategy of generic competition to bring down drug prices, a clear consensus is emerging that market entry of multiple suppliers is a critical factor in expeditiously bringing down prices of new vaccines. In this context, key target objectives for improving access to new vaccines include overcoming intellectual property obstacles, streamlining regulatory pathways for biosimilar vaccines, and reducing market entry timelines for developing-country vaccine manufacturers by transfer of technology and know-how. I propose an intellectual property, technology, and know-how bank as a new approach to facilitate widespread access to new vaccines in low- and middle-income countries by efficient transfer of patented vaccine technologies to multiple developing-country vaccine manufacturers. PMID:25211753

Developing Access Control Model of Web OLAP over Trusted and Collaborative Data Warehouses

NASA Astrophysics Data System (ADS)

Fugkeaw, Somchart; Mitrpanont, Jarernsri L.; Manpanpanich, Piyawit; Juntapremjitt, Sekpon

This paper proposes the design and development of Role- based Access Control (RBAC) model for the Single Sign-On (SSO) Web-OLAP query spanning over multiple data warehouses (DWs). The model is based on PKI Authentication and Privilege Management Infrastructure (PMI); it presents a binding model of RBAC authorization based on dimension privilege specified in attribute certificate (AC) and user identification. Particularly, the way of attribute mapping between DW user authentication and privilege of dimensional access is illustrated. In our approach, we apply the multi-agent system to automate flexible and effective management of user authentication, role delegation as well as system accountability. Finally, the paper culminates in the prototype system A-COLD (Access Control of web-OLAP over multiple DWs) that incorporates the OLAP features and authentication and authorization enforcement in the multi-user and multi-data warehouse environment.

Improving global access to new vaccines: intellectual property, technology transfer, and regulatory pathways.

PubMed

Crager, Sara Eve

2014-11-01

The 2012 World Health Assembly Global Vaccine Action Plan called for global access to new vaccines within 5 years of licensure. Current approaches have proven insufficient to achieve sustainable vaccine pricing within such a timeline. Paralleling the successful strategy of generic competition to bring down drug prices, a clear consensus is emerging that market entry of multiple suppliers is a critical factor in expeditiously bringing down prices of new vaccines. In this context, key target objectives for improving access to new vaccines include overcoming intellectual property obstacles, streamlining regulatory pathways for biosimilar vaccines, and reducing market entry timelines for developing-country vaccine manufacturers by transfer of technology and know-how. I propose an intellectual property, technology, and know-how bank as a new approach to facilitate widespread access to new vaccines in low- and middle-income countries by efficient transfer of patented vaccine technologies to multiple developing-country vaccine manufacturers.

[Improving global access to new vaccines: intellectual property, technology transfer, and regulatory pathways].

PubMed

Crager, Sara Eve

2015-01-01

The 2012 World Health Assembly Global Vaccine Action Plan called for global access to new vaccines within 5 years of licensure. Current approaches have proven insufficient to achieve sustainable vaccine pricing within such a timeline. Paralleling the successful strategy of generic competition to bring down drug prices, a clear consensus is emerging that market entry of multiple suppliers is a critical factor in expeditiously bringing down prices of new vaccines. In this context, key target objectives for improving access to new vaccines include overcoming intellectual property obstacles, streamlining regulatory pathways for biosimilar vaccines, and reducing market entry timelines for developing-country vaccine manufacturers by transfer of technology and know-how. I propose an intellectual property, technology, and know-how bank as a new approach to facilitate widespread access to new vaccines in low- and middle-income countries by efficient transfer of patented vaccine technologies to multiple developing-country vaccine manufacturers.

FD/DAMA Scheme For Mobile/Satellite Communications

NASA Technical Reports Server (NTRS)

Yan, Tsun-Yee; Wang, Charles C.; Cheng, Unjeng; Rafferty, William; Dessouky, Khaled I.

1992-01-01

Integrated-Adaptive Mobile Access Protocol (I-AMAP) proposed to allocate communication channels to subscribers in first-generation MSAT-X mobile/satellite communication network. Based on concept of frequency-division/demand-assigned multiple access (FD/DAMA) where partition of available spectrum adapted to subscribers' demands for service. Requests processed, and competing requests resolved according to channel-access protocol, or free-access tree algorithm described in "Connection Protocol for Mobile/Satellite Communications" (NPO-17735). Assigned spectrum utilized efficiently.

An Educational Rationale for Deaf Students with Multiple Disabilities

ERIC Educational Resources Information Center

Ewing, Karen M.; Jones, Thomas W.

2003-01-01

Deaf students with multiple disabilities have a long history of limited opportunity, including limited access to educational opportunities available to their deaf peers. This article places the individual needs of deaf students with multiple disabilities in the context that guides much of deaf education--the importance of language acquisition.…

A multiple camera tongue switch for a child with severe spastic quadriplegic cerebral palsy.

PubMed

Leung, Brian; Chau, Tom

2010-01-01

The present study proposed a video-based access technology that facilitated a non-contact tongue protrusion access modality for a 7-year-old boy with severe spastic quadriplegic cerebral palsy (GMFCS level 5). The proposed system featured a centre camera and two peripheral cameras to extend coverage of the frontal face view of this user for longer durations. The child participated in a descriptive case study. The participant underwent 3 months of tongue protrusion training while the multiple camera tongue switch prototype was being prepared. Later, the participant was brought back for five experiment sessions where he worked on a single-switch picture matching activity, using the multiple camera tongue switch prototype in a controlled environment. The multiple camera tongue switch achieved an average sensitivity of 82% and specificity of 80%. In three of the experiment sessions, the peripheral cameras were associated with most of the true positive switch activations. These activations would have been missed by a centre-camera-only setup. The study demonstrated proof-of-concept of a non-contact tongue access modality implemented by a video-based system involving three cameras and colour video processing.

An integrated voice and data multiple-access scheme for a land-mobile satellite system

NASA Technical Reports Server (NTRS)

Li, V. O. K.; Yan, T.-Y.

1984-01-01

An analytical study is performed of the satellite requirements for a land mobile satellite system (LMSS). The spacecraft (MSAT-X) would be in GEO and would be compatible with multiple access by mobile radios and antennas and fixed stations. The FCC has received a petition from NASA to reserve the 821-825 and 866-870 MHz frequencies for the LMSS, while communications with fixed earth stations would be in the Ku band. MSAT-X transponders would alter the frequencies of signal and do no processing in the original configuration considered. Channel use would be governed by an integrated demand-assigned, multiple access protocol, which would divide channels into reservation and information channels, governed by a network management center. Further analyses will cover tradeoffs between data and voice users, probability of blocking, and the performance impacts of on-board switching and variable bandwidth assignment. Initial calculations indicate that a large traffic volume can be handled with acceptable delays and voice blocking probabilities.

An integrated voice and data multiple-access scheme for a land-mobile satellite system

NASA Astrophysics Data System (ADS)

Li, V. O. K.; Yan, T.-Y.

1984-11-01

An analytical study is performed of the satellite requirements for a land mobile satellite system (LMSS). The spacecraft (MSAT-X) would be in GEO and would be compatible with multiple access by mobile radios and antennas and fixed stations. The FCC has received a petition from NASA to reserve the 821-825 and 866-870 MHz frequencies for the LMSS, while communications with fixed earth stations would be in the Ku band. MSAT-X transponders would alter the frequencies of signal and do no processing in the original configuration considered. Channel use would be governed by an integrated demand-assigned, multiple access protocol, which would divide channels into reservation and information channels, governed by a network management center. Further analyses will cover tradeoffs between data and voice users, probability of blocking, and the performance impacts of on-board switching and variable bandwidth assignment. Initial calculations indicate that a large traffic volume can be handled with acceptable delays and voice blocking probabilities.

User needs for propagation data

NASA Technical Reports Server (NTRS)

Sullivan, Thomas M.

1993-01-01

New and refined models of radio signal propagation phenomena are needed to support studies of evolving satellite services and systems. Taking an engineering perspective, applications for propagation measurements and models in the context of various types of analyses that are of ongoing interest are reviewed. Problems that were encountered in the signal propagation aspects of these analyses are reviewed, and potential solutions to these problems are discussed. The focus is on propagation measurements and models needed to support design and performance analyses of systems in the Mobile-Satellite Service (MSS) operating in the 1-3 GHz range. These systems may use geostationary or non-geostationary satellites and Frequency Division Multiple Access (FDMA), Time Division Multiple Access Digital (TDMA), or Code Division Multiple Access (CDMA) techniques. Many of the propagation issues raised in relation to MSS are also pertinent to other services such as broadcasting-satellite (sound) at 2310-2360 MHz. In particular, services involving mobile terminals or terminals with low gain antennas are of concern.

Transparent data service with multiple wireless access

NASA Technical Reports Server (NTRS)

Dean, Richard A.; Levesque, Allen H.

1993-01-01

The rapid introduction of digital wireless networks is an important part of the emerging digital communications scene. The introduction of Digital Cellular, LEO and GEO Satellites, and Personal Communications Services poses both a challenge and an opportunity for the data user. On the one hand wireless access will introduce significant new portable data services such as personal notebooks, paging, E-mail, and fax that will put the information age in the user's pocket. On the other hand the challenge of creating a seamless and transparent environment for the user in multiple access environments and across multiple network connections is formidable. A summary of the issues associated with developing techniques and standards that can support transparent and seamless data services is presented. The introduction of data services into the radio world represents a unique mix of RF channel problems, data protocol issues, and network issues. These problems require that experts from each of these disciplines fuse the individual technologies to support these services.

Wild versus domestic prey in the diet of reintroduced tigers (Panthera tigris) in the livestock-dominated multiple-use forests of Panna Tiger Reserve, India.

PubMed

Kolipaka, S S; Tamis, W L M; van 't Zelfde, M; Persoon, G A; de Iongh, H H

2017-01-01

Grazing livestock in openly accessible areas is a common practice in the multiple-use forests of India; however, its compatibility with the reintroduction of tigers to these areas requires examination. Here, we investigated the diet of tigers in a livestock-dominated multiple-use buffer zone of the Panna Tiger Reserve, India. We hypothesised that the presence of feral cattle, along with open-access grazing practices in multiple-use forests, would increase the incidence of predation on livestock by tigers, even when wild prey are available. We used generalised linear models to test whether predation of livestock versus wild animals was influenced by (1) the sex and age class of tigers, (2) season, and (3) the distance of prey from the core-zone boundary of the reserve. Overall, sub-adult tigers and male tigers killed more livestock than wild prey, even when wild prey was available. In the winter and rainy seasons livestock were killed in higher numbers in the buffer zone than in summers, this may be because of the seasonally changing livestock herding patterns in the area. Further, with increasing distance from the core-zone boundary, all tigers killed more livestock, possibly because livestock were more easily accessible than wild prey. Our results show that open-access and unregulated livestock grazing is not currently compatible with large carnivore conservation in the same landscape. Such practices will lead to an increase in negative tiger-human-livestock interactions. In conclusion, we suggest the need to encourage locals to corral valuable cattle, leaving feral/unwanted livestock for tigers. This simple strategy would benefit both local inhabitants and tiger conservation in the multiple-use forests of India.

Wild versus domestic prey in the diet of reintroduced tigers (Panthera tigris) in the livestock-dominated multiple-use forests of Panna Tiger Reserve, India

PubMed Central

Tamis, W. L. M.; van ‘t Zelfde, M.; Persoon, G. A.; de Iongh, H. H.

2017-01-01

Grazing livestock in openly accessible areas is a common practice in the multiple-use forests of India; however, its compatibility with the reintroduction of tigers to these areas requires examination. Here, we investigated the diet of tigers in a livestock-dominated multiple-use buffer zone of the Panna Tiger Reserve, India. We hypothesised that the presence of feral cattle, along with open-access grazing practices in multiple-use forests, would increase the incidence of predation on livestock by tigers, even when wild prey are available. We used generalised linear models to test whether predation of livestock versus wild animals was influenced by (1) the sex and age class of tigers, (2) season, and (3) the distance of prey from the core-zone boundary of the reserve. Overall, sub-adult tigers and male tigers killed more livestock than wild prey, even when wild prey was available. In the winter and rainy seasons livestock were killed in higher numbers in the buffer zone than in summers, this may be because of the seasonally changing livestock herding patterns in the area. Further, with increasing distance from the core-zone boundary, all tigers killed more livestock, possibly because livestock were more easily accessible than wild prey. Our results show that open-access and unregulated livestock grazing is not currently compatible with large carnivore conservation in the same landscape. Such practices will lead to an increase in negative tiger-human-livestock interactions. In conclusion, we suggest the need to encourage locals to corral valuable cattle, leaving feral/unwanted livestock for tigers. This simple strategy would benefit both local inhabitants and tiger conservation in the multiple-use forests of India. PMID:28379997

The base rates and factors associated with reported access to firearms in psychiatric inpatients.

PubMed

Kolla, Bhanu Prakash; O'Connor, Stephen S; Lineberry, Timothy W

2011-01-01

The aim of this study was to define whether specific patient demographic groups, diagnoses or other factors are associated with psychiatric inpatients reporting firearms access. A retrospective medical records review study was conducted using information on access to firearms from electronic medical records for all patients 16 years and older admitted between July 2007 and May 2008 at the Mayo Clinic Psychiatric Hospital in Rochester, MN. Data were obtained only on patients providing authorization for record review. Data were analyzed using univariate and multivariate logistic regression analyses accounting for gender, diagnostic groups, comorbid substance use, history of suicide attempts and family history of suicide/suicide attempts. Seventy-four percent (1169/1580) of patients provided research authorization. The ratio of men to women was identical in both research and nonresearch authorization groups. There were 14.6% of inpatients who reported firearms access. In univariate analysis, men were more likely (P<.0001) to report access than women, and a history of previous suicide attempt(s) was associated with decreased access (P=.02). Multiple logistic regression analyses controlling for other factors found females and patients with history of previous suicide attempt(s) less likely to report access, while patients with a family history of suicide or suicide attempts reported increased firearms access. Diagnostic groups were not associated with access on univariate or multiple logistic regression analyses. Men and inpatients with a family history of suicide/suicide attempts were more likely to report firearms access. Clinicians should develop standardized systems of identification of firearms access and provide guidance on removal. Copyright © 2011 Elsevier Inc. All rights reserved.

"My Daughter Does Not Know How to Make the Chappati": Understanding Food Access among African Immigrants in Lewiston, Maine

ERIC Educational Resources Information Center

Jacobus, Michelle Vazquez; Ahmed, Hussein; Jalali, Reza

2013-01-01

Food access for Maine's growing African refugee population reflects multiple levels of general access to society. To better understand the challenges and opportunities unique to this community, a multidisciplinary team of students, faculty, and community partners integrated the expertise of local residents with the results of a food assessment of…

Post-coma persons with extensive multiple disabilities use microswitch technology to access selected stimulus events or operate a radio device.

PubMed

Lancioni, Giulio E; Singh, Nirbhay N; O'Reilly, Mark F; Sigafoos, Jeff; Alberti, Gloria; Oliva, Doretta; Megna, Gianfranco; Iliceto, Carla; Damiani, Sabino; Ricci, Irene; Spica, Antonella

2011-01-01

The present two studies extended research evidence on the use of microswitch technology by post-coma persons with multiple disabilities. Specifically, Study I examined whether three adults with a diagnosis of minimally conscious state and multiple disabilities could use microswitches as tools to access brief, selected stimulus events. Study II assessed whether an adult, who had emerged from a minimally conscious state but was affected by multiple disabilities, could manage the use of a radio device via a microswitch-aided program. Results showed that the participants of Study I had a significant increase of microswitch responding during the intervention phases. The participant of Study II learned to change radio stations and seemed to spend different amounts of session time on the different stations available (suggesting preferences among the programs characterizing them). The importance of microswitch technology for assisting post-coma persons with multiple disabilities to positively engage with their environment was discussed. Copyright © 2011 Elsevier Ltd. All rights reserved.

IMPROVING ACCESS TO INFORMATION ABOUT ORD PROJECTS

EPA Science Inventory

ORD project information is maintained in, and retrieved from, multiple systems and home pages. Not all sources of project information are Intranet accessible. Descriptive information may be abbreviated and not useful in conveying a comprehensive understanding of a project. The m...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forslund, D.W.; Cook, J.L.

One of the most powerful tools available for telemedicine is a multimedia medical record accessible over a wide area and simultaneously editable by multiple physicians. The ability to do this through an intuitive interface linking multiple distributed data repositories while maintaining full data integrity is a fundamental enabling technology in healthcare. The authors discuss the role of distributed object technology using Java and CORBA in providing this capability including an example of such a system (TeleMed) which can be accessed through the World Wide Web. Issues of security, scalability, data integrity, and usability are emphasized.

Why is CDMA the solution for mobile satellite communication

NASA Technical Reports Server (NTRS)

Gilhousen, Klein S.; Jacobs, Irwin M.; Padovani, Roberto; Weaver, Lindsay A.

1989-01-01

It is demonstrated that spread spectrum Code Division Multiple Access (CDMA) systems provide an economically superior solution to satellite mobile communications by increasing the system maximum capacity with respect to single channel per carrier Frequency Division Multiple Access (FDMA) systems. Following the comparative analysis of CDMA and FDMA systems, the design of a model that was developed to test the feasibility of the approach and the performance of a spread spectrum system in a mobile environment. Results of extensive computer simulations as well as laboratory and field tests results are presented.

Lowering data retention voltage in static random access memory array by post fabrication self-improvement of cell stability by multiple stress application

NASA Astrophysics Data System (ADS)

Mizutani, Tomoko; Takeuchi, Kiyoshi; Saraya, Takuya; Kobayashi, Masaharu; Hiramoto, Toshiro

2018-04-01

We propose a new version of the post fabrication static random access memory (SRAM) self-improvement technique, which utilizes multiple stress application. It is demonstrated that, using a device matrix array (DMA) test element group (TEG) with intrinsic channel fully depleted (FD) silicon-on-thin-buried-oxide (SOTB) six-transistor (6T) SRAM cells fabricated by the 65 nm technology, the lowering of data retention voltage (DRV) is more effectively achieved than using the previously proposed single stress technique.

Comparison of FDMA and CDMA for second generation land-mobile satellite communications

NASA Technical Reports Server (NTRS)

Yongacoglu, A.; Lyons, R. G.; Mazur, B. A.

1990-01-01

Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA) (both analog and digital) systems capacities are compared on the basis of identical link availabilities and physical propagation models. Parameters are optimized for a bandwidth limited, multibeam environment. For CDMA, the benefits of voice activated carriers, antenna discrimination, polarization reuse, return link power control and multipath suppression are included in the analysis. For FDMA, the advantages of bandwidth efficient modulation/coding combinations, voice activated carriers, polarization reuse, beam placement, and frequency staggering were taken into account.

The role of CORBA in enabling telemedicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forslund, D.W.

1997-07-01

One of the most powerful tools available for telemedicine is a multimedia medical record accessible over a wide area and simultaneously editable by multiple physicians. The ability to do this through an intuitive interface linking multiple distributed data repositories while maintaining full data integrity is a fundamental enabling technology in healthcare. The author discusses the role of distributed object technology using CORBA in providing this capability including an example of such a system (TeleMed) which can be accessed through the World Wide Web. Issues of security, scalability, data integrity, and useability are emphasized.

Construction of a virtual EPR and automated contextual linkage to multiple sources of support information on the Oxford Clinical Intranet.

PubMed

Kay, J D; Nurse, D

1999-01-01

We have used internet-standard tools to provide access for clinicians to the components of the electronic patient record held on multiple remote disparate systems. Through the same interface we have provided access to multiple knowledgebases, some written locally and others published elsewhere. We have developed linkage between these two types of information which removes the need for the user to drill down into each knowledgebase to search for relevant information. This approach may help in the implementation of evidence-based practice. The major problems appear to be semantic rather than technological. The intranet was developed at low cost and is now in routine use. This approach appears to be transferable across systems and organisations.

Optical Multiple Access Network (OMAN) for advanced processing satellite applications

NASA Technical Reports Server (NTRS)

Mendez, Antonio J.; Gagliardi, Robert M.; Park, Eugene; Ivancic, William D.; Sherman, Bradley D.

1991-01-01

An OMAN breadboard for exploring advanced processing satellite circuit switch applications is introduced. Network architecture, hardware trade offs, and multiple user interference issues are presented. The breadboard test set up and experimental results are discussed.

Visualization of Multi-mission Astronomical Data with ESASky

NASA Astrophysics Data System (ADS)

Baines, Deborah; Giordano, Fabrizio; Racero, Elena; Salgado, Jesús; López Martí, Belén; Merín, Bruno; Sarmiento, María-Henar; Gutiérrez, Raúl; Ortiz de Landaluce, Iñaki; León, Ignacio; de Teodoro, Pilar; González, Juan; Nieto, Sara; Segovia, Juan Carlos; Pollock, Andy; Rosa, Michael; Arviset, Christophe; Lennon, Daniel; O'Mullane, William; de Marchi, Guido

2017-02-01

ESASky is a science-driven discovery portal to explore the multi-wavelength sky and visualize and access multiple astronomical archive holdings. The tool is a web application that requires no prior knowledge of any of the missions involved and gives users world-wide simplified access to the highest-level science data products from multiple astronomical space-based astronomy missions plus a number of ESA source catalogs. The first public release of ESASky features interfaces for the visualization of the sky in multiple wavelengths, the visualization of query results summaries, and the visualization of observations and catalog sources for single and multiple targets. This paper describes these features within ESASky, developed to address use cases from the scientific community. The decisions regarding the visualization of large amounts of data and the technologies used were made to maximize the responsiveness of the application and to keep the tool as useful and intuitive as possible.

Identifying Opportunities for Decision Support Systems in Support of Regional Resource Use Planning: An Approach Through Soft Systems Methodology.

PubMed

Zhu; Dale

2000-10-01

/ Regional resource use planning relies on key regional stakeholder groups using and having equitable access to appropriate social, economic, and environmental information and assessment tools. Decision support systems (DSS) can improve stakeholder access to such information and analysis tools. Regional resource use planning, however, is a complex process involving multiple issues, multiple assessment criteria, multiple stakeholders, and multiple values. There is a need for an approach to DSS development that can assist in understanding and modeling complex problem situations in regional resource use so that areas where DSSs could provide effective support can be identified, and the user requirements can be well established. This paper presents an approach based on the soft systems methodology for identifying DSS opportunities for regional resource use planning, taking the Central Highlands Region of Queensland, Australia, as a case study.

Barriers to prompt and effective malaria treatment among the poorest population in Kenya.

PubMed

Chuma, Jane; Okungu, Vincent; Molyneux, Catherine

2010-05-27

Prompt access to effective malaria treatment is central to the success of malaria control worldwide, but few fevers are treated with effective anti-malarials within 24 hours of symptoms onset. The last two decades saw an upsurge of initiatives to improve access to effective malaria treatment in many parts of sub-Saharan Africa. Evidence suggests that the poorest populations remain least likely to seek prompt and effective treatment, but the factors that prevent them from accessing interventions are not well understood. With plans under way to subsidize ACT heavily in Kenya and other parts of Africa, there is urgent need to identify policy actions to promote access among the poor. This paper explores access barriers to effective malaria treatment among the poorest population in four malaria endemic districts in Kenya. The study was conducted in the poorest areas of four malaria endemic districts in Kenya. Multiple data collection methods were applied including: a cross-sectional survey (n=708 households); 24 focus group discussions; semi-structured interviews with health workers (n=34); and patient exit interviews (n=359). Multiple factors related to affordability, acceptability and availability interact to influence access to prompt and effective treatment. Regarding affordability, about 40 percent of individuals who self-treated using shop-bought drugs and 42 percent who visited a formal health facility reported not having enough money to pay for treatment, and having to adopt coping strategies including borrowing money and getting treatment on credit in order to access care. Other factors influencing affordability were seasonality of illness and income sources, transport costs, and unofficial payments. Regarding acceptability, the major interrelated factors identified were provider patient relationship, patient expectations, beliefs on illness causation, perceived effectiveness of treatment, distrust in the quality of care and poor adherence to treatment regimes. Availability barriers identified were related to facility opening hours, organization of health care services, drug and staff shortages. Ensuring that all individuals suffering from malaria have prompt access to effective treatment remains a challenge for resource constrained health systems. Policy actions to address the multiple barriers of access should be designed around access dimensions, and should include broad interventions to revitalize the public health care system. Unless additional efforts are directed towards addressing access barriers among the poor and vulnerable, malaria will remain a major cause of morbidity and mortality in sub-Saharan Africa.

Network Access Control List Situation Awareness

ERIC Educational Resources Information Center

Reifers, Andrew

2010-01-01

Network security is a large and complex problem being addressed by multiple communities. Nevertheless, current theories in networking security appear to overestimate network administrators' ability to understand network access control lists (NACLs), providing few context specific user analyses. Consequently, the current research generally seems to…

Distributed observing facility for remote access to multiple telescopes

NASA Astrophysics Data System (ADS)

Callegari, Massimo; Panciatici, Antonio; Pasian, Fabio; Pucillo, Mauro; Santin, Paolo; Aro, Simo; Linde, Peter; Duran, Maria A.; Rodriguez, Jose A.; Genova, Francoise; Ochsenbein, Francois; Ponz, J. D.; Talavera, Antonio

2000-06-01

The REMOT (Remote Experiment Monitoring and conTrol) project was financed by 1996 by the European Community in order to investigate the possibility of generalizing the remote access to scientific instruments. After the feasibility of this idea was demonstrated, the DYNACORE (DYNAmically, COnfigurable Remote Experiment monitoring and control) project was initiated as a REMOT follow-up. Its purpose is to develop software technology to support scientists in two different domains, astronomy and plasma physics. The resulting system allows (1) simultaneous multiple user access to different experimental facilities, (2) dynamic adaptability to different kinds of real instruments, (3) exploitation of the communication infrastructures features, (4) ease of use through intuitive graphical interfaces, and (5) additional inter-user communication using off-the-shelf projects such as video-conference tools, chat programs and shared blackboards.

Dual-balanced detection scheme with optical hard-limiters in an optical code division multiple access system

NASA Astrophysics Data System (ADS)

Liu, Maw-Yang; Hsu, Yi-Kai

2017-03-01

Three-arm dual-balanced detection scheme is studied in an optical code division multiple access system. As the MAI and beat noise are the main deleterious source of system performance, we utilize optical hard-limiters to alleviate such channel impairment. In addition, once the channel condition is improved effectively, the proposed two-dimensional error correction code can remarkably enhance the system performance. In our proposed scheme, the optimal thresholds of optical hard-limiters and decision circuitry are fixed, and they will not change with other system parameters. Our proposed scheme can accommodate a large number of users simultaneously and is suitable for burst traffic with asynchronous transmission. Therefore, it is highly recommended as the platform for broadband optical access network.

Who's Got the Booze? The Role of Access to Alcohol in the Relations Between Social Status and Individual Use.

PubMed

Deutsch, Arielle R; Steinley, Douglas; Sher, Kenneth J; Slutske, Wendy S

2017-09-01

The findings of previous research that examined relationships between popularity and alcohol use in adolescents have been mixed, and few hypotheses have proposed mechanisms for this relationship. The current study expands on previous literature (a) by examining a possible mechanism that can explain the relation between popularity and alcohol use (home access to alcohol) and (b) by using another sociometric measure ("betweenness"), beyond popularity, that may relate more to home alcohol access. Using network-level data from adolescents in 9th-11th grades in eight schools within two in-home waves of the National Longitudinal Study of Adolescent to Adult Health (Add Health), we examined two sociometric measures of social status: popularity (number of schoolmates who nominated participants as a friend) and betweenness (level of ties participants have to multiple social subgroups within a network). Betweenness, but not popularity, related to later alcohol use. Having home access to alcohol positively related to later alcohol use, and having friends with home access to alcohol negatively related to later alcohol use. Alcohol access was also related to later sociometric status. Friends' alcohol access negatively related to later betweenness, and personal alcohol access moderated other pathways predicting betweenness. Betweenness appears to play a unique role in the association between social status and alcohol use in adolescent social networks. This is potentially tied to specific ways in which adolescents may be able to access alcohol (through home or through friends with access at home). More research is necessary to examine the ways in which multiple sociometric statuses relate to the contexts in which adolescents access and use alcohol.

76 FR 7213 - ACRAnet, Inc.; SettlementOne Credit Corporation, and Sackett National Holdings, Inc.; Fajilan and...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-02-09

... allege that hackers were able to exploit vulnerabilities in the computer networks of multiple end user clients, putting all consumer reports in those networks at risk. In multiple breaches, hackers accessed...

An Evaluation of a Three-Component Multiple Schedule to Indicate Attention Availability

ERIC Educational Resources Information Center

Nava, Maria J.; Vargo, Kristina K.; Babino, Misti M.

2016-01-01

Students may engage in high rates of social approach responses at inappropriate times throughout the school day. One intervention that has been used to teach students appropriate and inappropriate times to access attention is a multiple schedule of reinforcement. In this study, we evaluated the efficacy of a multiple schedule that indicated when…

Development of a Prototype System for Accessing Linked NCES Data. Working Paper Series.

ERIC Educational Resources Information Center

Salvucci, Sameena; Wenck, Stephen; Tyson, James

A project has been developed to advance the capabilities of the National Center for Education Statistics (NCES) to support the dissemination of linked data from multiple surveys, multiple components within a survey, and multiple time points. An essential element of this study is the development of a software prototype system to facilitate NCES…

Concept and implementation of the Globalstar mobile satellite system

NASA Technical Reports Server (NTRS)

Schindall, Joel

1995-01-01

Globalstar is a satellite-based mobile communications system which provides quality wireless communications (voice and/or data) anywhere in the world except the polar regions. The Globalstar system concept is based upon technological advancements in Low Earth Orbit (LEO) satellite technology and in cellular telephone technology, including the commercial application of Code Division Multiple Access (CDMA) technologies. The Globalstar system uses elements of CDMA and Frequency Division Multiple Access (FDMA), combined with satellite Multiple Beam Antenna (MBA) technology and advanced variable-rate vocoder technology to arrive at one of the most efficient modulation and multiple access systems ever proposed for a satellite communications system. The technology used in Globalstar includes the following techniques in obtaining high spectral efficiency and affordable cost per channel: (1) CDMA modulation with efficient power control; (2) high efficiency vocoder with voice activity factor; (3) spot beam antenna for increased gain and frequency reuse; (4) weighted satellite antenna gain for broad geographic coverage; (5) multisatellite user links (diversity) to enhance communications reliability; and (6) soft hand-off between beams and satellites. Initial launch is scheduled in 1997 and the system is scheduled to be operational in 1998. The Globalstar system utilizes frequencies in L-, S- and C-bands which have the potential to offer worldwide availability with authorization by the appropriate regulatory agencies.

Unique Access to Learning

ERIC Educational Resources Information Center

Goble, Don

2009-01-01

This article describes the many learning opportunities that broadcast technology students at Ladue Horton Watkins High School in St. Louis, Missouri, experience because of their unique access to technology and methods of learning. Through scaffolding, stepladder techniques, and trial by fire, students learn to produce multiple television programs,…

Line drawing titled 'TDRS Spacecraft On-Orbit Configuration'

NASA Technical Reports Server (NTRS)

1988-01-01

Line drawing titled 'TDRS Spacecraft On-Orbit Configuration' identifies the various tracking and data relay satellite (TDRS) components (solar arrays, C-Band antenna, K-Band antenna, space ground link (SGL) antenna, single access antennas, multiple access antenna, omni antenna, solar sail). A TDRS will be deployed during the STS-26 mission. Including the space shuttle, the TDRS will be equipped to support up to 26 user spacecraft simultaneously. It will provide two types of service: 1) multiple access which can relay data from as many as 20 low data rate (100 bits per second to 50 kilobits per second) user satellites simultaneously and; 2) single access which will provide two high data rate (to 300 megabits per second) communication relays. The TDRS is three-axis stabilizrd with the body fixed antennas pointing constantly at the Earth while the solar arrays track the Sun. TDR satellites do no processing of user traffic in either direction. Rather, they operate as 'bent pipe' repeaters,

Optical beat interference noise reduction in OFDMA optical access link using self-homodyne balanced detection

NASA Astrophysics Data System (ADS)

Jung, Sang-Min; Won, Yong-Yuk; Han, Sang-Kook

2013-12-01

A Novel technique for reducing the OBI noise in optical OFDMA-PON uplink is presented. OFDMA is a multipleaccess/ multiplexing scheme that can provide multiplexing operation of user data streams onto the downlink sub-channels and uplink multiple access by means of dividing OFDM subcarriers as sub-channels. The main issue of high-speed, single-wavelength upstream OFDMA-PON arises from optical beating interference noise. Because the sub-channels are allocated dynamically to multiple access users over same nominal wavelength, it generates the optical beating interference among upstream signals. In this paper, we proposed a novel scheme using self-homodyne balanced detection in the optical line terminal (OLT) to reduce OBI noise which is generated in the uplink transmission of OFDMA-PON system. When multiple OFDMA sub-channels over the same nominal wavelength are received at the same time in the proposed architecture, OBI noises can be removed using balanced detection. Using discrete multitone modulation (DMT) to generate real valued OFDM signals, the proposed technique is verified through experimental demonstration.

Writing and applications of fiber Bragg grating arrays

NASA Astrophysics Data System (ADS)

LaRochelle, Sophie; Cortes, Pierre-Yves; Fathallah, H.; Rusch, Leslie A.; Jaafar, H. B.

2000-12-01

Multiple Bragg gratings are written in a single fibre strand with accurate positioning to achieve predetermined time delays between optical channels. Applications of fibre Bragg grating arrays include encoders/decoders with series of identical gratings for optical code-division multiple access.

What Are the Factors Influencing Implementation of Advanced Access in Family Medicine Units? A Cross-Case Comparison of Four Early Adopters in Quebec

PubMed Central

Touati, Nassera; Maillet, Lara; Gaboury, Isabelle

2017-01-01

Introduction Advanced access is an organizational model that has shown promise in improving timely access to primary care. In Quebec, it has recently been introduced in several family medicine units (FMUs) with a teaching mission. The objectives of this paper are to analyze the principles of advanced access implemented in FMUs and to identify which factors influenced their implementation. Methods A multiple case study of four purposefully selected FMUs was conducted. Data included document analysis and 40 semistructured interviews with health professionals and staff. Cross-case comparison and thematic analysis were performed. Results Three out of four FMUs implemented the key principles of advanced access at various levels. One scheduling pattern was observed: 90% of open appointment slots over three- to four-week periods and 10% of prebooked appointments. Structural and organizational factors facilitated the implementation: training of staff to support change, collective leadership, and openness to change. Conversely, family physicians practicing in multiple clinical settings, lack of team resources, turnover of clerical staff, rotation of medical residents, and management capacity were reported as major barriers to implementing the model. Conclusion Our results call for multilevel implementation strategies to improve the design of the advanced access model in academic teaching settings. PMID:28775899

Dynamic Network Selection for Multicast Services in Wireless Cooperative Networks

NASA Astrophysics Data System (ADS)

Chen, Liang; Jin, Le; He, Feng; Cheng, Hanwen; Wu, Lenan

In next generation mobile multimedia communications, different wireless access networks are expected to cooperate. However, it is a challenging task to choose an optimal transmission path in this scenario. This paper focuses on the problem of selecting the optimal access network for multicast services in the cooperative mobile and broadcasting networks. An algorithm is proposed, which considers multiple decision factors and multiple optimization objectives. An analytic hierarchy process (AHP) method is applied to schedule the service queue and an artificial neural network (ANN) is used to improve the flexibility of the algorithm. Simulation results show that by applying the AHP method, a group of weight ratios can be obtained to improve the performance of multiple objectives. And ANN method is effective to adaptively adjust weight ratios when users' new waiting threshold is generated.

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

PubMed

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.

Iterative MMSE Detection for MIMO/BLAST DS-CDMA Systems in Frequency Selective Fading Channels - Achieving High Performance in Fully Loaded Systems

NASA Astrophysics Data System (ADS)

Silva, João Carlos; Souto, Nuno; Cercas, Francisco; Dinis, Rui

A MMSE (Minimum Mean Square Error) DS-CDMA (Direct Sequence-Code Division Multiple Access) receiver coupled with a low-complexity iterative interference suppression algorithm was devised for a MIMO/BLAST (Multiple Input, Multiple Output / Bell Laboratories Layered Space Time) system in order to improve system performance, considering frequency selective fading channels. The scheme is compared against the simple MMSE receiver, for both QPSK and 16QAM modulations, under SISO (Single Input, Single Output) and MIMO systems, the latter with 2Tx by 2Rx and 4Tx by 4Rx (MIMO order 2 and 4 respectively) antennas. To assess its performance in an existing system, the uncoded UMTS HSDPA (High Speed Downlink Packet Access) standard was considered.

Inferring geographic origin of barley accessions using molecular markers

USDA-ARS?s Scientific Manuscript database

The USDA Agricultural Research Service (ARS) National Small Grains Collection (NSGC) has 207 landrace barleys obtained from a nursery grown in the Ukraine in 1930 by N.I. Vavilov, many of which have multiple resistance (MR) to disease similar to accessions from Ethiopia. Vavilov collected germplasm ...

Deja Vu--The Access/Success Pendulum

ERIC Educational Resources Information Center

Gandara, Patricia; Orfield, Gary

2010-01-01

In education, reform tends to follow cycles, often bouncing from one extreme to another without considering the possibility of incorporating multiple perspectives simultaneously. Policies aimed at helping more underrepresented students enter college and complete degrees have bounced from one pole to another, embracing access as the primary goal…

Investing in Digital

ERIC Educational Resources Information Center

Grogg, Jill E.

2007-01-01

Librarians face two very pressing charges: make voluminous numbers of electronic resources as visible as possible in a landscape with multiple access points, and simultaneously manage all the technology, tasks, and data necessary to facilitate such ubiquitous access. In the past ten years, solutions have emerged and become commonplace in many…

Computer Access. Tech Use Guide: Using Computer Technology.

ERIC Educational Resources Information Center

Council for Exceptional Children, Reston, VA. Center for Special Education Technology.

One of nine brief guides for special educators on using computer technology, this guide focuses on access including adaptations in input devices, output devices, and computer interfaces. Low technology devices include "no-technology" devices (usually modifications to existing devices), simple switches, and multiple switches. High technology input…

Analysis of hybrid subcarrier multiplexing of OCDMA based on single photodiode detection

NASA Astrophysics Data System (ADS)

Ahmad, N. A. A.; Junita, M. N.; Aljunid, S. A.; Rashidi, C. B. M.; Endut, R.

2017-11-01

This paper analyzes the performance of subcarrier multiplexing (SCM) of spectral amplitude coding optical code multiple access (SAC-OCDMA) by applying Recursive Combinatorial (RC) code based on single photodiode detection (SPD). SPD is used in the receiver part to reduce the effect of multiple access interference (MAI) which contributes as a dominant noise in incoherent SAC-OCDMA systems. Results indicate that the SCM OCDMA network performance could be improved by using lower data rates and higher number of weight. Total number of users can also be enhanced by adding lower data rates and higher number of subcarriers.

Attentional priorities and access to short-term memory: parietal interactions.

PubMed

Gillebert, Céline R; Dyrholm, Mads; Vangkilde, Signe; Kyllingsbæk, Søren; Peeters, Ronald; Vandenberghe, Rik

2012-09-01

The intraparietal sulcus (IPS) has been implicated in selective attention as well as visual short-term memory (VSTM). To contrast mechanisms of target selection, distracter filtering, and access to VSTM, we combined behavioral testing, computational modeling and functional magnetic resonance imaging. Sixteen healthy subjects participated in a change detection task in which we manipulated both target and distracter set sizes. We directly compared the IPS response as a function of the number of targets and distracters in the display and in VSTM. When distracters were not present, the posterior and middle segments of IPS showed the predicted asymptotic activity increase with an increasing target set size. When distracters were added to a single target, activity also increased as predicted. However, the addition of distracters to multiple targets suppressed both middle and posterior IPS activities, thereby displaying a significant interaction between the two factors. The interaction between target and distracter set size in IPS could not be accounted for by a simple explanation in terms of number of items accessing VSTM. Instead, it led us to a model where items accessing VSTM receive differential weights depending on their behavioral relevance, and secondly, a suppressive effect originates during the selection phase when multiple targets and multiple distracters are simultaneously present. The reverse interaction between target and distracter set size was significant in the right temporoparietal junction (TPJ), where activity was highest for a single target compared to any other condition. Our study reconciles the role of middle IPS in attentional selection and biased competition with its role in VSTM access. Copyright © 2012 Elsevier Inc. All rights reserved.

CRAVE: a database, middleware and visualization system for phenotype ontologies.

PubMed

Gkoutos, Georgios V; Green, Eain C J; Greenaway, Simon; Blake, Andrew; Mallon, Ann-Marie; Hancock, John M

2005-04-01

A major challenge in modern biology is to link genome sequence information to organismal function. In many organisms this is being done by characterizing phenotypes resulting from mutations. Efficiently expressing phenotypic information requires combinatorial use of ontologies. However tools are not currently available to visualize combinations of ontologies. Here we describe CRAVE (Concept Relation Assay Value Explorer), a package allowing storage, active updating and visualization of multiple ontologies. CRAVE is a web-accessible JAVA application that accesses an underlying MySQL database of ontologies via a JAVA persistent middleware layer (Chameleon). This maps the database tables into discrete JAVA classes and creates memory resident, interlinked objects corresponding to the ontology data. These JAVA objects are accessed via calls through the middleware's application programming interface. CRAVE allows simultaneous display and linking of multiple ontologies and searching using Boolean and advanced searches.

47 CFR 14.52 - Copies; service; separate filings against multiple defendants.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 47 Telecommunication 1 2014-10-01 2014-10-01 false Copies; service; separate filings against multiple defendants. 14.52 Section 14.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL ACCESS TO ADVANCED COMMUNICATIONS SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Recordkeeping, Consumer...

47 CFR 14.52 - Copies; service; separate filings against multiple defendants.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 47 Telecommunication 1 2012-10-01 2012-10-01 false Copies; service; separate filings against multiple defendants. 14.52 Section 14.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL ACCESS TO ADVANCED COMMUNICATIONS SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Recordkeeping, Consumer...

47 CFR 14.52 - Copies; service; separate filings against multiple defendants.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 47 Telecommunication 1 2013-10-01 2013-10-01 false Copies; service; separate filings against multiple defendants. 14.52 Section 14.52 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL ACCESS TO ADVANCED COMMUNICATIONS SERVICES AND EQUIPMENT BY PEOPLE WITH DISABILITIES Recordkeeping, Consumer...

Generation-based memory synchronization in a multiprocessor system with weakly consistent memory accesses

DOEpatents

Ohmacht, Martin

2017-08-15

In a multiprocessor system, a central memory synchronization module coordinates memory synchronization requests responsive to memory access requests in flight, a generation counter, and a reclaim pointer. The central module communicates via point-to-point communication. The module includes a global OR reduce tree for each memory access requesting device, for detecting memory access requests in flight. An interface unit is implemented associated with each processor requesting synchronization. The interface unit includes multiple generation completion detectors. The generation count and reclaim pointer do not pass one another.

Generation-based memory synchronization in a multiprocessor system with weakly consistent memory accesses

DOEpatents

Ohmacht, Martin

2014-09-09

In a multiprocessor system, a central memory synchronization module coordinates memory synchronization requests responsive to memory access requests in flight, a generation counter, and a reclaim pointer. The central module communicates via point-to-point communication. The module includes a global OR reduce tree for each memory access requesting device, for detecting memory access requests in flight. An interface unit is implemented associated with each processor requesting synchronization. The interface unit includes multiple generation completion detectors. The generation count and reclaim pointer do not pass one another.

A Systematic Scheme for Multiple Access in Ethernet Passive Optical Access Networks

NASA Astrophysics Data System (ADS)

Ma, Maode; Zhu, Yongqing; Hiang Cheng, Tee

2005-11-01

While backbone networks have experienced substantial changes in the last decade, access networks have not changed much. Recently, passive optical networks (PONs) seem to be ready for commercial deployment as access networks, due to the maturity of a number of enabling technologies. Among the PON technologies, Ethernet PON (EPON) standardized by the IEEE 802.3ah Ethernet in the First Mile (EFM) Task Force is the most attractive one because of its high speed, low cost, familiarity, interoperability, and low overhead. In this paper, we consider the issue of upstream channel sharing in the EPONs. We propose a novel multiple-access control scheme to provide bandwidth-guaranteed service for high-demand customers, while providing best effort service to low-demand customers according to the service level agreement (SLA). The analytical and simulation results prove that the proposed scheme performs best in what it is designed to do compared to another well-known scheme that has not considered providing differentiated services. With business customers preferring premium services with guaranteed bandwidth and residential users preferring low-cost best effort services, our scheme could benefit both groups of subscribers, as well as the operators.

Developing a composite index of spatial accessibility across different health care sectors: A German example.

PubMed

Siegel, Martin; Koller, Daniela; Vogt, Verena; Sundmacher, Leonie

2016-02-01

The evolving lack of ambulatory care providers especially in rural areas increasingly challenges the strict separation between ambulatory and inpatient care in Germany. Some consider allowing hospitals to treat ambulatory patients to tackle potential shortages of ambulatory care in underserved areas. In this paper, we develop an integrated index of spatial accessibility covering multiple dimensions of health care. This index may contribute to the empirical evidence concerning potential risks and benefits of integrating the currently separated health care sectors. Accessibility is measured separately for each type of care based on official data at the district level. Applying an Improved Gravity Model allows us to factor in potential cross-border utilization. We combine the accessibilities for each type of care into a univariate index by adapting the concept of regional multiple deprivation measurement to allow for a limited substitutability between health care sectors. The results suggest that better health care accessibility in urban areas persists when taking a holistic view. We believe that this new index may provide an empirical basis for an inter-sectoral capacity planning. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Timing divided attention.

PubMed

Hogendoorn, Hinze; Carlson, Thomas A; VanRullen, Rufin; Verstraten, Frans A J

2010-11-01

Visual attention can be divided over multiple objects or locations. However, there is no single theoretical framework within which the effects of dividing attention can be interpreted. In order to develop such a model, here we manipulated the stage of visual processing at which attention was divided, while simultaneously probing the costs of dividing attention on two dimensions. We show that dividing attention incurs dissociable time and precision costs, which depend on whether attention is divided during monitoring or during access. Dividing attention during monitoring resulted in progressively delayed access to attended locations as additional locations were monitored, as well as a one-off precision cost. When dividing attention during access, time costs were systematically lower at one of the accessed locations than at the other, indicating that divided attention during access, in fact, involves rapid sequential allocation of undivided attention. We propose a model in which divided attention is understood as the simultaneous parallel preparation and subsequent sequential execution of multiple shifts of undivided attention. This interpretation has the potential to bring together diverse findings from both the divided-attention and saccade preparation literature and provides a framework within which to integrate the broad spectrum of divided-attention methodologies.

Undersea Communication Network Self-Localization during the Unet󈧌 Seatrial

DTIC Science & Technology

2010-06-01

Multiple Access Collision Avoidance ( MACA ) suitable for underwater networks [6]. Control frames are short 9-byte utility packets which are...Proceedings of the MILCOM’08 Conference, San Diego, CA, USA, November 2008. [6] P. Karn, MACA --a new channel access method for packet radio, in ARRL/CRRL

Are CD-ROM LANs a Thing of the Past?

ERIC Educational Resources Information Center

Mehta, Apurva

1996-01-01

Remote access to full-text and CD-ROM databases using the Internet has advantages over a CD-ROM local area network. Topics include speed, document delivery, multiple platforms, technical support, licensing, copyright, and access to graphics. Considerations of duplication of information, platform compatibility, print versus digital media, back…

Widening Access, Widening Participation, Widening Success: An Indian Case Study

ERIC Educational Resources Information Center

Thornton, Mary

2006-01-01

Multiple deprivations are widespread in rural India. Literacy levels remain stubbornly low, albeit gradually improving. Caste, class, religion, gender, age and disability all impact on access to education, participation and successful completion. The education of girls remains problematic given the higher value attached to sons, especially in…

Opening our science: Open science and cyanobacterial research at the US EPA

EPA Science Inventory

In this blog post we introduce the idea of Open Science and discuss multiple ways we are implementing these concepts in our cyanobacteria research. We give examples of our open access publications, open source code that support our research, and provide open access to our resear...

Electronic Reference Library: Silverplatter's Database Networking Solution.

ERIC Educational Resources Information Center

Millea, Megan

Silverplatter's Electronic Reference Library (ERL) provides wide area network access to its databases using TCP/IP communications and client-server architecture. ERL has two main components: The ERL clients (retrieval interface) and the ERL server (search engines). ERL clients provide patrons with seamless access to multiple databases on multiple…

Managing intellectual property to develop medicines for the world's poorest.

PubMed

Fonteilles-Drabek, Sylvie; Reddy, David; Wells, Timothy N C

2017-04-01

It has been argued that patents impede the development and access of medicines for tropical diseases such as malaria. However, we believe that intellectual property can be a key tool to enable timely progression of drug development projects involving multiple partners and to ensure equitable access to successful products.

An Access Control and Trust Management Framework for Loosely-Coupled Multidomain Environments

ERIC Educational Resources Information Center

Zhang, Yue

2010-01-01

Multidomain environments where multiple organizations interoperate with each other are becoming a reality as can be seen in emerging Internet-based enterprise applications. Access control to ensure secure interoperation in such an environment is a crucial challenge. A multidomain environment can be categorized as "tightly-coupled" and…

Providing Students with Severe Disabilities Access to the General Education Curriculum

ERIC Educational Resources Information Center

Olson, Amy; Leko, Melinda M.; Roberts, Carly A.

2016-01-01

This case study explored how multiple educational personnel in a middle school identified as an exemplar of inclusive education defined and provided students with severe disabilities access to the general education curriculum. Data sources including a questionnaire, interviews, observations, observation reflections, and artifacts were collected…

Digital Exclusion: Coming out from behind Closed Doors

ERIC Educational Resources Information Center

Watling, Sue

2011-01-01

Government visions of a digital future show little indication of how disabled people, reliant on access technology, will participate. Access technology has the potential to offer independent use of the Internet but many disabled people already face barriers that prevent them having equitable digital experiences. Multiple obstacles include high…

Why Atens Enjoy Enhanced Accessibility for Human Space Flight

NASA Technical Reports Server (NTRS)

Barbee, Brent W.; Adamo, Daniel R.

2011-01-01

Near-Earth objects can be grouped into multiple orbit classifications, among them being the Aten group, whose members have orbits crossing Earth's with semi-major axes less than 1 astronomical unit. Atens comprise well under 10% of known near-Earth objects. This is in dramatic contrast to results from recent human space flight near-Earth object accessibility studies, where the most favorable known destinations are typically almost 50% Atens. Geocentric dynamics explain this enhanced Aten accessibility and lead to an understanding of where the most accessible near-Earth objects reside. Without a comprehensive space-based survey, however, highly accessible Atens will remain largely unknown.

Channel Access in Erlang

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nicklaus, Dennis J.

2013-10-13

We have developed an Erlang language implementation of the Channel Access protocol. Included are low-level functions for encoding and decoding Channel Access protocol network packets as well as higher level functions for monitoring or setting EPICS process variables. This provides access to EPICS process variables for the Fermilab Acnet control system via our Erlang-based front-end architecture without having to interface to C/C++ programs and libraries. Erlang is a functional programming language originally developed for real-time telecommunications applications. Its network programming features and list management functions make it particularly well-suited for the task of managing multiple Channel Access circuits and PVmore » monitors.« less

Secure, web-accessible call rosters for academic radiology departments.

PubMed

Nguyen, A V; Tellis, W M; Avrin, D E

2000-05-01

Traditionally, radiology department call rosters have been posted via paper and bulletin boards. Frequently, changes to these lists are made by multiple people independently, but often not synchronized, resulting in confusion among the house staff and technical staff as to who is on call and when. In addition, multiple and disparate copies exist in different sections of the department, and changes made would not be propagated to all the schedules. To eliminate such difficulties, a paperless call scheduling application was developed. Our call scheduling program allowed Java-enabled web access to a database by designated personnel from each radiology section who have privileges to make the necessary changes. Once a person made a change, everyone accessing the database would see the modification. This eliminates the chaos resulting from people swapping shifts at the last minute and not having the time to record or broadcast the change. Furthermore, all changes to the database were logged. Users are given a log-in name and password and can only edit their section; however, all personnel have access to all sections' schedules. Our applet was written in Java 2 using the latest technology in database access. We access our Interbase database through the DataExpress and DB Swing (Borland, Scotts Valley, CA) components. The result is secure access to the call rosters via the web. There are many advantages to the web-enabled access, mainly the ability for people to make changes and have the changes recorded and propagated in a single virtual location and available to all who need to know.

Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks.

PubMed

Lyu, Bin; Yang, Zhen; Gui, Guan; Sari, Hikmet

2017-06-01

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model.

Optimal Time Allocation in Backscatter Assisted Wireless Powered Communication Networks

PubMed Central

Lyu, Bin; Yang, Zhen; Gui, Guan; Sari, Hikmet

2017-01-01

This paper proposes a wireless powered communication network (WPCN) assisted by backscatter communication (BackCom). This model consists of a power station, an information receiver and multiple users that can work in either BackCom mode or harvest-then-transmit (HTT) mode. The time block is mainly divided into two parts corresponding to the data backscattering and transmission periods, respectively. The users first backscatter data to the information receiver in time division multiple access (TDMA) during the data backscattering period. When one user works in the BackCom mode, the other users harvest energy from the power station. During the data transmission period, two schemes, i.e., non-orthogonal multiple access (NOMA) and TDMA, are considered. To maximize the system throughput, the optimal time allocation policies are obtained. Simulation results demonstrate the superiority of the proposed model. PMID:28587171

A hybrid MAC protocol design for energy-efficient very-high-throughput millimeter wave, wireless sensor communication networks

NASA Astrophysics Data System (ADS)

Jian, Wei; Estevez, Claudio; Chowdhury, Arshad; Jia, Zhensheng; Wang, Jianxin; Yu, Jianguo; Chang, Gee-Kung

2010-12-01

This paper presents an energy-efficient Medium Access Control (MAC) protocol for very-high-throughput millimeter-wave (mm-wave) wireless sensor communication networks (VHT-MSCNs) based on hybrid multiple access techniques of frequency division multiplexing access (FDMA) and time division multiplexing access (TDMA). An energy-efficient Superframe for wireless sensor communication network employing directional mm-wave wireless access technologies is proposed for systems that require very high throughput, such as high definition video signals, for sensing, processing, transmitting, and actuating functions. Energy consumption modeling for each network element and comparisons among various multi-access technologies in term of power and MAC layer operations are investigated for evaluating the energy-efficient improvement of proposed MAC protocol.

FINDING A COMMON DATA REPRESENTATION AND INTERCHANGE APPROACH FOR MULTIMEDIA MODELS

EPA Science Inventory

Within many disciplines, multiple approaches are used to represent and access very similar data (e.g., a time series of values), often due to the lack of commonly accepted standards. When projects must use data from multiple disciplines, the problems quickly compound. Often sig...

Measuring and reducing college students' procrastination.

PubMed

Perrin, Christopher J; Miller, Neal; Haberlin, Alayna T; Ivy, Jonathan W; Meindl, James N; Neef, Nancy A

2011-01-01

We examined college students' procrastination when studying for weekly in-class quizzes. Two schedules of online practice quiz delivery were compared using a multiple baseline design. When online study material was made available noncontingently, students usually procrastinated. When access to additional study material was contingent on completing previous study material, studying was more evenly distributed. Overall, the mean gain in percentage correct scores on weekly in-class quizzes relative to pretests was greater during contingent access than during noncontingent access conditions.

Searching to Translate and Translating to Search: When Information Retrieval Meets Machine Translation

ERIC Educational Resources Information Center

Ture, Ferhan

2013-01-01

With the adoption of web services in daily life, people have access to tremendous amounts of information, beyond any human's reading and comprehension capabilities. As a result, search technologies have become a fundamental tool for accessing information. Furthermore, the web contains information in multiple languages, introducing another barrier…

The US EPA CompTox Chemistry Dashboard as a source of data to fill data gaps for chemical sources of risk

EPA Science Inventory

Chemical risk assessment is both time-consuming and difficult because it requires the assembly of data for chemicals generally distributed across multiple sources. The US EPA CompTox Chemistry Dashboard is a publicly accessible web-based application providing access to various da...

Newer Technologies for School Security. ERIC Digest Number 145.

ERIC Educational Resources Information Center

Schneider, Tod

This digest describes several technologies that can be used to control access to, and improve surveillance of, school grounds. Access can be controlled by using "smart" cards to control keyed entries. Many schools have problems with multiple copies of keys, and these card systems are integrated with computer software that allows for…

Communication and Empowerment: A Place for Rich and Multiple Media?

ERIC Educational Resources Information Center

Bunning, Karen; Heath, Becky; Minnion, Andy

2009-01-01

Background: Project @pple (Access & Participation for People with intellectual disability in Learning Environments) was about exploring the terms on which young people with intellectual disability access and participate with e-Learning and the Web. The current study is one of a number of related studies. It explores the culture of information and…

Acquired Severe Disabilities and Complex Health Care Needs: Access to Inclusive Education

ERIC Educational Resources Information Center

Ballard, Sarah L.; Dymond, Stacy K.

2016-01-01

This case study examined one high school student's access to inclusive education and experiences in an inclusive English class after he acquired severe disabilities and complex health care needs from a nontraumatic brain injury. Multiple sources of data (i.e., interviews, field notes, and documents) were collected and analyzed to formulate…

Strategies for Disseminating Information on Biomedical Research on Autism to Hispanic Parents

ERIC Educational Resources Information Center

Lajonchere, Clara M.; Wheeler, Barbara Y.; Valente, Thomas W.; Kreutzer, Cary; Munson, Aron; Narayanan, Shrikanth; Kazemzadeh, Abe; Cruz, Roxana; Martinez, Irene; Schrager, Sheree M.; Schweitzer, Lisa; Chklovski, Tara; Hwang, Darryl

2016-01-01

Low income Hispanic families experience multiple barriers to accessing evidence-based information on Autism Spectrum Disorders (ASD). This study utilized a mixed-strategy intervention to create access to information in published bio-medical research articles on ASD by distilling the content into parent-friendly English- and Spanish-language ASD…

Embedded controller for GEM detector readout system

NASA Astrophysics Data System (ADS)

Zabołotny, Wojciech M.; Byszuk, Adrian; Chernyshova, Maryna; Cieszewski, Radosław; Czarski, Tomasz; Dominik, Wojciech; Jakubowska, Katarzyna L.; Kasprowicz, Grzegorz; Poźniak, Krzysztof; Rzadkiewicz, Jacek; Scholz, Marek

2013-10-01

This paper describes the embedded controller used for the multichannel readout system for the GEM detector. The controller is based on the embedded Mini ITX mainboard, running the GNU/Linux operating system. The controller offers two interfaces to communicate with the FPGA based readout system. FPGA configuration and diagnostics is controlled via low speed USB based interface, while high-speed setup of the readout parameters and reception of the measured data is handled by the PCI Express (PCIe) interface. Hardware access is synchronized by the dedicated server written in C. Multiple clients may connect to this server via TCP/IP network, and different priority is assigned to individual clients. Specialized protocols have been implemented both for low level access on register level and for high level access with transfer of structured data with "msgpack" protocol. High level functionalities have been split between multiple TCP/IP servers for parallel operation. Status of the system may be checked, and basic maintenance may be performed via web interface, while the expert access is possible via SSH server. System was designed with reliability and flexibility in mind.

System level comparison of FDMA vs. CDMA (under conference guideline constraint)

NASA Technical Reports Server (NTRS)

Renshaw, Ken

1989-01-01

The margin that is required to mitigate the near-far problem in a Code Division Multiple Access (CDMA) mobile satellite system is determined by the radio-propagation model selected, the distribution of the users in clear and shadowed environments, and implementation techniques. The use of revenue potential as a means of evaluating the relative merits of CDMA and Frequency Division Multiple Access (FDMA) systems is a convenient way to rationalize the performance of systems using high-gain and low-gain antennas. The revenue potential of CDMA is much greater than the revenue potential for FDMA for a particular satellite design considered.

OCDMA Over WDM PON—Solution Path to Gigabit-Symmetric FTTH

NASA Astrophysics Data System (ADS)

Kitayama, Ken-Ichi; Wang, Xu; Wada, Naoya

2006-04-01

It will be revealed that a myth of deploying low bit-rate uplink fiber-to-the-home (FTTH) services while providing a high bit-rate downlink is wrong. Therefore, for the future broadband FTTH services, the focus should be on the capability to provide gigabit-or even multigigabits-per-second both in up-and downlinks, namely gigabit symmetric systems. Optical code-division multiple access (OCDMA) now deserves a revisit as a powerful alternative to time-division multiple access and wavelength-division multiple (WDM) access in FTTH systems. In this paper, the authors will first highlight the OCDMA systems. The system architecture and its operation principle, code design, optical en/decoding, using a long superstructured fiber Bragg grating (SSFBG) en/decoder, and its system performance will be described. Next, an OCDMA over WDM passive optical network (PON) as a solution for the gigabit-symmetric FTTH systems will be proposed. The system architecture and the WDM interchannel crosstalk will be studied. It will be shown that by taking advantage of reflection spectrum notches of the SSFBG en/decoder, the WDM interchannel crosstalk can be suppressed and can enable OCDMA over WDM PON to simultaneously provide multigigabit-per-second up-and downlinks to a large number of users.

Hermitian symmetry free optical-single-carrier frequency division multiple access for visible light communication

NASA Astrophysics Data System (ADS)

Azim, Ali W.; Le Guennec, Yannis; Maury, Ghislaine

2018-05-01

Optical-orthogonal frequency division multiplexing (O-OFDM) is an effective scheme for visible light communications (VLC), offering a candid extension to multiple access (MA) scenarios, i.e., O-OFDMA. However, O-OFDMA exhibits high peak-to-average power ratio (PAPR), which exacerbates the non-linear distortions from the light emitting diode (LED). To overcome high PAPR while sustaining MA, optical-single-carrier frequency-division multiple access (O-SCFDMA) is used. For both O-OFDMA and O-SCFDMA, Hermitian symmetry (HS) constraint is imposed in frequency-domain (FD) to obtain a real-valued time-domain (TD) signal for intensity modulation-direct detection (IM-DD) implementation of VLC. Howbeit, HS results in an increase of PAPR for O-SCFDMA. In this regard, we propose HS free (HSF) O-SCFDMA (HSFO-SCFDMA). We compare HSFO-SCFDMA with several approaches in key parameters, such as, bit error rate (BER), optical power penalty, PAPR, quantization, electrical power efficiency and system complexity. BER performance and optical power penalty is evaluated considering multipath VLC channel and taking into account the bandwidth limitation of LED in combination with its optimized driver. It is illustrated that HSFO-SCFDMA outperforms other alternatives.

Non-Orthogonal Multiple Access for Ubiquitous Wireless Sensor Networks.

PubMed

Anwar, Asim; Seet, Boon-Chong; Ding, Zhiguo

2018-02-08

Ubiquitous wireless sensor networks (UWSNs) have become a critical technology for enabling smart cities and other ubiquitous monitoring applications. Their deployment, however, can be seriously hampered by the spectrum available to the sheer number of sensors for communication. To support the communication needs of UWSNs without requiring more spectrum resources, the power-domain non-orthogonal multiple access (NOMA) technique originally proposed for 5th Generation (5G) cellular networks is investigated for UWSNs for the first time in this paper. However, unlike 5G networks that operate in the licensed spectrum, UWSNs mostly operate in unlicensed spectrum where sensors also experience cross-technology interferences from other devices sharing the same spectrum. In this paper, we model the interferences from various sources at the sensors using stochastic geometry framework. To evaluate the performance, we derive a theorem and present new closed form expression for the outage probability of the sensors in a downlink scenario under interference limited environment. In addition, diversity analysis for the ordered NOMA users is performed. Based on the derived outage probability, we evaluate the average link throughput and energy consumption efficiency of NOMA against conventional orthogonal multiple access (OMA) technique in UWSNs. Further, the required computational complexity for the NOMA users is presented.

Microprocessor-controlled, wide-range streak camera

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amy E. Lewis, Craig Hollabaugh

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storagemore » using flash-based storage media. The camera’s user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.« less

A Novel Multiple-Access Correlation-Delay-Shift-Keying

NASA Astrophysics Data System (ADS)

Duan, J. Y.; Jiang, G. P.; Yang, H.

In Correlation-Delay-Shift-Keying (CDSK), the reference signal and the information-bearing signal are added together during a certain time delay. Because the reference signal is not strictly orthogonal to the information-bearing signal, the cross-correlation between the adjacent chaotic signal (Intra-signal Interference, ISI) will be introduced into the demodulation at the receiver. Therefore, the Bit-Error Ratio (BER) of CDSK is higher than that of Differential-Chaos-Shift-Keying (DCSK). To avoid the ISI component and enhance the BER performance of CDSK in multiuser scenario, Multiple-Access CDSK with No Intra-signal Interference (MA-CDSK-NII) is proposed. By constructing the repeated chaotic generator and applying the Walsh code sequence to modulate the reference signal, in MA-CDSK-NII, the ISI component will be eliminated during the demodulation. Gaussian approximation method is adopted here to obtain the exact performance analysis of MA-CDSK-NII over additive white Gaussian noise (AWGN) channel and Rayleigh multipath fading channels. Results show that, due to no ISI component and lower transmitting power, the BER performance of MA-CDSK-NII can be better than that of multiple-access CDSK and Code-Shifted Differential-Chaos-Shift-Keying (CS-DCSK).

Microprocessor-controlled wide-range streak camera

NASA Astrophysics Data System (ADS)

Lewis, Amy E.; Hollabaugh, Craig

2006-08-01

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera's user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.

Optical multiple access techniques for on-board routing

NASA Technical Reports Server (NTRS)

Mendez, Antonio J.; Park, Eugene; Gagliardi, Robert M.

1992-01-01

The purpose of this research contract was to design and analyze an optical multiple access system, based on Code Division Multiple Access (CDMA) techniques, for on board routing applications on a future communication satellite. The optical multiple access system was to effect the functions of a circuit switch under the control of an autonomous network controller and to serve eight (8) concurrent users at a point to point (port to port) data rate of 180 Mb/s. (At the start of this program, the bit error rate requirement (BER) was undefined, so it was treated as a design variable during the contract effort.) CDMA was selected over other multiple access techniques because it lends itself to bursty, asynchronous, concurrent communication and potentially can be implemented with off the shelf, reliable optical transceivers compatible with long term unattended operations. Temporal, temporal/spatial hybrids and single pulse per row (SPR, sometimes termed 'sonar matrices') matrix types of CDMA designs were considered. The design, analysis, and trade offs required by the statement of work selected a temporal/spatial CDMA scheme which has SPR properties as the preferred solution. This selected design can be implemented for feasibility demonstration with off the shelf components (which are identified in the bill of materials of the contract Final Report). The photonic network architecture of the selected design is based on M(8,4,4) matrix codes. The network requires eight multimode laser transmitters with laser pulses of 0.93 ns operating at 180 Mb/s and 9-13 dBm peak power, and 8 PIN diode receivers with sensitivity of -27 dBm for the 0.93 ns pulses. The wavelength is not critical, but 830 nm technology readily meets the requirements. The passive optical components of the photonic network are all multimode and off the shelf. Bit error rate (BER) computations, based on both electronic noise and intercode crosstalk, predict a raw BER of (10 exp -3) when all eight users are communicating concurrently. If better BER performance is required, then error correction codes (ECC) using near term electronic technology can be used. For example, the M(8,4,4) optical code together with Reed-Solomon (54,38,8) encoding provides a BER of better than (10 exp -11). The optical transceiver must then operate at 256 Mb/s with pulses of 0.65 ns because the 'bits' are now channel symbols.

The academic, economic and societal impacts of Open Access: an evidence-based review.

PubMed

Tennant, Jonathan P; Waldner, François; Jacques, Damien C; Masuzzo, Paola; Collister, Lauren B; Hartgerink, Chris H J

2016-01-01

Ongoing debates surrounding Open Access to the scholarly literature are multifaceted and complicated by disparate and often polarised viewpoints from engaged stakeholders. At the current stage, Open Access has become such a global issue that it is critical for all involved in scholarly publishing, including policymakers, publishers, research funders, governments, learned societies, librarians, and academic communities, to be well-informed on the history, benefits, and pitfalls of Open Access. In spite of this, there is a general lack of consensus regarding the potential pros and cons of Open Access at multiple levels. This review aims to be a resource for current knowledge on the impacts of Open Access by synthesizing important research in three major areas: academic, economic and societal. While there is clearly much scope for additional research, several key trends are identified, including a broad citation advantage for researchers who publish openly, as well as additional benefits to the non-academic dissemination of their work. The economic impact of Open Access is less well-understood, although it is clear that access to the research literature is key for innovative enterprises, and a range of governmental and non-governmental services. Furthermore, Open Access has the potential to save both publishers and research funders considerable amounts of financial resources, and can provide some economic benefits to traditionally subscription-based journals. The societal impact of Open Access is strong, in particular for advancing citizen science initiatives, and leveling the playing field for researchers in developing countries. Open Access supersedes all potential alternative modes of access to the scholarly literature through enabling unrestricted re-use, and long-term stability independent of financial constraints of traditional publishers that impede knowledge sharing. However, Open Access has the potential to become unsustainable for research communities if high-cost options are allowed to continue to prevail in a widely unregulated scholarly publishing market. Open Access remains only one of the multiple challenges that the scholarly publishing system is currently facing. Yet, it provides one foundation for increasing engagement with researchers regarding ethical standards of publishing and the broader implications of 'Open Research'.

The academic, economic and societal impacts of Open Access: an evidence-based review

PubMed Central

Tennant, Jonathan P.; Waldner, François; Jacques, Damien C.; Masuzzo, Paola; Collister, Lauren B.; Hartgerink, Chris. H. J.

2016-01-01

Ongoing debates surrounding Open Access to the scholarly literature are multifaceted and complicated by disparate and often polarised viewpoints from engaged stakeholders. At the current stage, Open Access has become such a global issue that it is critical for all involved in scholarly publishing, including policymakers, publishers, research funders, governments, learned societies, librarians, and academic communities, to be well-informed on the history, benefits, and pitfalls of Open Access. In spite of this, there is a general lack of consensus regarding the potential pros and cons of Open Access at multiple levels. This review aims to be a resource for current knowledge on the impacts of Open Access by synthesizing important research in three major areas: academic, economic and societal. While there is clearly much scope for additional research, several key trends are identified, including a broad citation advantage for researchers who publish openly, as well as additional benefits to the non-academic dissemination of their work. The economic impact of Open Access is less well-understood, although it is clear that access to the research literature is key for innovative enterprises, and a range of governmental and non-governmental services. Furthermore, Open Access has the potential to save both publishers and research funders considerable amounts of financial resources, and can provide some economic benefits to traditionally subscription-based journals. The societal impact of Open Access is strong, in particular for advancing citizen science initiatives, and leveling the playing field for researchers in developing countries. Open Access supersedes all potential alternative modes of access to the scholarly literature through enabling unrestricted re-use, and long-term stability independent of financial constraints of traditional publishers that impede knowledge sharing. However, Open Access has the potential to become unsustainable for research communities if high-cost options are allowed to continue to prevail in a widely unregulated scholarly publishing market. Open Access remains only one of the multiple challenges that the scholarly publishing system is currently facing. Yet, it provides one foundation for increasing engagement with researchers regarding ethical standards of publishing and the broader implications of 'Open Research'. PMID:27158456

Current State of Overlapping, Concurrent, and Multiple-Room Surgery in Otolaryngology: A National Survey.

PubMed

Cognetti, David M; Nussenbaum, Brian; Brenner, Michael J; Chi, David H; McCormick, Michael E; Venkatraman, Giri; Zhan, Tingting; McKinlay, Alex J

2017-12-01

Objective Multiple-room surgery has gained attention due to reports in the lay press scrutinizing the activity, with hospitals and the government collecting data on current practice. We studied practices and attitudes toward multiple-room surgery in otolaryngology. Methods A survey was developed by members of the Patient Safety and Quality Improvement Committee of the American Academy of Otolaryngology-Head and Neck Surgery. The survey was distributed to members of the Academy and included questions on demographics, current practices, and opinions regarding multiple-room surgery. The survey was designed to capture the spectrum of multidisciplinary, overlapping, and simultaneous/concurrent surgery practices. Data were collected via SurveyMonkey. Results A total of 907 of 9520 members completed the survey. Of the respondents, 40.4% reported performing some form of multiple-room surgery. Multiple-room surgery is more common amongst subspecialists than general otolaryngologists. Most believed that regulations disallowing multiple-room surgery would result in an increase in late starts (73.5%), an increase in the time to schedule surgery (84.5%), a detriment to residency training (63.1%), and no improvement in patient safety (60%.) Discussion Multiple-room surgery is common among responding otolaryngologists. Most respondents consider the practice to serve a role in facilitating access, efficiency, and training. Implications for Practice Due to recent attention placed on multiple-room surgery, institutions are reviewing policies regarding the practice. This survey suggests that policy changes that restrict multiple-room surgery must consider a potential unintended negative impact on patient care and access.

Multiple Voices, Multiple Genres: Fiction for Young Adults.

ERIC Educational Resources Information Center

Gillis, Candida

2002-01-01

Notes that with so many multivoice novels accessible to teens, there is a great opportunity to expand students' reading repertoire. Proposes that young adult novels are an excellent transition to classic literature that may seem remote or difficult. Offers advice on teaching multivoice novels. Concludes that multivoice novels show young readers…

The Design of Lessons Using Mathematics Analysis Software to Support Multiple Representations in Secondary School Mathematics

ERIC Educational Resources Information Center

Pierce, Robyn; Stacey, Kaye; Wander, Roger; Ball, Lynda

2011-01-01

Current technologies incorporating sophisticated mathematical analysis software (calculation, graphing, dynamic geometry, tables, and more) provide easy access to multiple representations of mathematical problems. Realising the affordances of such technology for students' learning requires carefully designed lessons. This paper reports on design…

77 FR 33486 - Certain Integrated Circuit Packages Provided With Multiple Heat-Conducting Paths and Products...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-06

... INTERNATIONAL TRADE COMMISSION [Docket No. 2899] Certain Integrated Circuit Packages Provided With... complaint entitled Certain Integrated Circuit Packages Provided With Multiple Heat-Conducting Paths and..., telephone (202) 205-2000. The public version of the complaint can be accessed on the Commission's electronic...

Adaptive Digital Signature Design and Short-Data-Record Adaptive Filtering

DTIC Science & Technology

2008-04-01

rate BPSK binary phase shift keying CA − CFAR cell averaging− constant false alarm rate CDMA code − division multiple − access CFAR constant false...Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation criterion,” EURASIP Journal...415-428, Mar. 2002. [6] P. Cotae, “Spreading sequence design for multiple cell synchronous DS-CDMA systems under total weighted squared correlation

Optimization of knowledge sharing through multi-forum using cloud computing architecture

NASA Astrophysics Data System (ADS)

Madapusi Vasudevan, Sriram; Sankaran, Srivatsan; Muthuswamy, Shanmugasundaram; Ram, N. Sankar

2011-12-01

Knowledge sharing is done through various knowledge sharing forums which requires multiple logins through multiple browser instances. Here a single Multi-Forum knowledge sharing concept is introduced which requires only one login session which makes user to connect multiple forums and display the data in a single browser window. Also few optimization techniques are introduced here to speed up the access time using cloud computing architecture.

Household trends in access to improved water sources and sanitation facilities in Vietnam and associated factors: findings from the Multiple Indicator Cluster Surveys, 2000-2011.

PubMed

Tuyet-Hanh, Tran Thi; Lee, Jong-Koo; Oh, Juhwan; Van Minh, Hoang; Ou Lee, Chul; Hoan, Le Thi; Nam, You-Seon; Long, Tran Khanh

2016-01-01

Despite progress made by the Millennium Development Goal (MDG) number 7.C, Vietnam still faces challenges with regard to the provision of access to safe drinking water and basic sanitation. This paper describes household trends in access to improved water sources and sanitation facilities separately, and analyses factors associated with access to improved water sources and sanitation facilities in combination. Secondary data from the Vietnam Multiple Indicator Cluster Survey in 2000, 2006, and 2011 were analyzed. Descriptive statistics and tests of significance describe trends over time in access to water and sanitation by location, demographic and socio-economic factors. Binary logistic regressions (2000, 2006, and 2011) describe associations between access to water and sanitation, and geographic, demographic, and socio-economic factors. There have been some outstanding developments in access to improved water sources and sanitation facilities from 2000 to 2011. In 2011, the proportion of households with access to improved water sources and sanitation facilities reached 90% and 77%, respectively, meeting the 2015 MDG targets for safe drinking water and basic sanitation set at 88% and 75%, respectively. However, despite these achievements, in 2011, only 74% of households overall had access to combined improved drinking water and sanitation facilities. There were also stark differences between regions. In 2011, only 47% of households had access to both improved water and sanitation facilities in the Mekong River Delta compared with 94% in the Red River Delta. In 2011, households in urban compared to rural areas were more than twice as likely (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.9-2.5) to have access to improved water and sanitation facilities in combination, and households in the highest compared with the lowest wealth quintile were over 40 times more likely (OR: 42.3; 95% CI: 29.8-60.0). More efforts are required to increase household access to both improved water and sanitation facilities in the Mekong River Delta, South East and Central Highlands regions of Vietnam. There is also a need to address socio-economic factors associated with inadequate access to improved sanitation facilities.

The INDIGO-Datacloud Authentication and Authorization Infrastructure

NASA Astrophysics Data System (ADS)

Ceccanti, A.; Hardt, M.; Wegh, B.; Millar, AP; Caberletti, M.; Vianello, E.; Licehammer, S.

2017-10-01

Contemporary distributed computing infrastructures (DCIs) are not easily and securely accessible by scientists. These computing environments are typically hard to integrate due to interoperability problems resulting from the use of different authentication mechanisms, identity negotiation protocols and access control policies. Such limitations have a big impact on the user experience making it hard for user communities to port and run their scientific applications on resources aggregated from multiple providers. The INDIGO-DataCloud project wants to provide the services and tools needed to enable a secure composition of resources from multiple providers in support of scientific applications. In order to do so, a common AAI architecture has to be defined that supports multiple authentication mechanisms, support delegated authorization across services and can be easily integrated in off-the-shelf software. In this contribution we introduce the INDIGO Authentication and Authorization Infrastructure, describing its main components and their status and how authentication, delegation and authorization flows are implemented across services.

Embedded diagnostic, prognostic, and health management system and method for a humanoid robot

NASA Technical Reports Server (NTRS)

Barajas, Leandro G. (Inventor); Strawser, Philip A (Inventor); Sanders, Adam M (Inventor); Reiland, Matthew J (Inventor)

2013-01-01

A robotic system includes a humanoid robot with multiple compliant joints, each moveable using one or more of the actuators, and having sensors for measuring control and feedback data. A distributed controller controls the joints and other integrated system components over multiple high-speed communication networks. Diagnostic, prognostic, and health management (DPHM) modules are embedded within the robot at the various control levels. Each DPHM module measures, controls, and records DPHM data for the respective control level/connected device in a location that is accessible over the networks or via an external device. A method of controlling the robot includes embedding a plurality of the DPHM modules within multiple control levels of the distributed controller, using the DPHM modules to measure DPHM data within each of the control levels, and recording the DPHM data in a location that is accessible over at least one of the high-speed communication networks.

Tecnologias mas nuevas para la seguridad escolar (Newer Technologies for School Security). ERIC Digest.

ERIC Educational Resources Information Center

Schneider, Tod

This digest in Spanish describes several technologies that can be used to control access to, and improve surveillance of, school grounds. Access can be controlled by using "smart" cards to control keyed entries. Many schools have problems with multiple copies of keys, and these card systems are integrated with computer software that…

77 FR 66454 - Gulf LNG Liquefaction Company, LLC; Application for Long-Term Authorization To Export Liquefied...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-05

... integrated U.S. natural gas pipeline system. GLLC notes that due to the Gulf LNG Terminal's direct access to multiple major interstate pipelines and indirect access to the national gas pipeline grid, the Project's... possible impacts that the Export Project might have on natural gas supply and pricing. Navigant's analysis...

Video Modeling and Observational Learning to Teach Gaming Access to Students with ASD

ERIC Educational Resources Information Center

Spriggs, Amy D.; Gast, David L.; Knight, Victoria F.

2016-01-01

The purpose of this study was to evaluate both video modeling and observational learning to teach age-appropriate recreation and leisure skills (i.e., accessing video games) to students with autism spectrum disorder. Effects of video modeling were evaluated via a multiple probe design across participants and criteria for mastery were based on…

Useful, Used, and Peer Approved: The Importance of Rigor and Accessibility in Postsecondary Research and Evaluation. WISCAPE Viewpoints

ERIC Educational Resources Information Center

Vaade, Elizabeth; McCready, Bo

2012-01-01

Traditionally, researchers, policymakers, and practitioners have perceived a tension between rigor and accessibility in quantitative research and evaluation in postsecondary education. However, this study indicates that both producers and consumers of these studies value high-quality work and clear findings that can reach multiple audiences. The…

ViSA: A Neurodynamic Model for Visuo-Spatial Working Memory, Attentional Blink, and Conscious Access

ERIC Educational Resources Information Center

Simione, Luca; Raffone, Antonino; Wolters, Gezinus; Salmas, Paola; Nakatani, Chie; Belardinelli, Marta Olivetti; van Leeuwen, Cees

2012-01-01

Two separate lines of study have clarified the role of selectivity in conscious access to visual information. Both involve presenting multiple targets and distracters: one "simultaneously" in a spatially distributed fashion, the other "sequentially" at a single location. To understand their findings in a unified framework, we propose a…

Designing Programs for Multiple Configurations: "You Mean Everyone Doesn't Have a Pentium or Better!"

ERIC Educational Resources Information Center

Conkright, Thomas D.; Joliat, Judy

1996-01-01

Discusses the challenges, solutions, and compromises involved in creating computer-delivered training courseware for Apollo Travel Services, a company whose 50,000 agents must access a mainframe from many different computing configurations. Initial difficulties came in trying to manage random access memory and quicken response time, but the future…

Iowa Flood Information System: Towards Integrated Data Management, Analysis and Visualization

NASA Astrophysics Data System (ADS)

Demir, I.; Krajewski, W. F.; Goska, R.; Mantilla, R.; Weber, L. J.; Young, N.

2012-04-01

The Iowa Flood Information System (IFIS) is a web-based platform developed by the Iowa Flood Center (IFC) to provide access to flood inundation maps, real-time flood conditions, flood forecasts both short-term and seasonal, flood-related data, information and interactive visualizations for communities in Iowa. The key element of the system's architecture is the notion of community. Locations of the communities, those near streams and rivers, define basin boundaries. The IFIS provides community-centric watershed and river characteristics, weather (rainfall) conditions, and streamflow data and visualization tools. Interactive interfaces allow access to inundation maps for different stage and return period values, and flooding scenarios with contributions from multiple rivers. Real-time and historical data of water levels, gauge heights, and rainfall conditions are available in the IFIS by streaming data from automated IFC bridge sensors, USGS stream gauges, NEXRAD radars, and NWS forecasts. Simple 2D and 3D interactive visualizations in the IFIS make the data more understandable to general public. Users are able to filter data sources for their communities and selected rivers. The data and information on IFIS is also accessible through web services and mobile applications. The IFIS is optimized for various browsers and screen sizes to provide access through multiple platforms including tablets and mobile devices. The IFIS includes a rainfall-runoff forecast model to provide a five-day flood risk estimate for around 500 communities in Iowa. Multiple view modes in the IFIS accommodate different user types from general public to researchers and decision makers by providing different level of tools and details. River view mode allows users to visualize data from multiple IFC bridge sensors and USGS stream gauges to follow flooding condition along a river. The IFIS will help communities make better-informed decisions on the occurrence of floods, and will alert communities in advance to help minimize damage of floods. This presentation provides an overview and live demonstration of the tools and interfaces in the IFIS developed to date to provide a platform for one-stop access to flood related data, visualizations, flood conditions, and forecast.

Iowa Flood Information System

NASA Astrophysics Data System (ADS)

Demir, I.; Krajewski, W. F.; Goska, R.; Mantilla, R.; Weber, L. J.; Young, N.

2011-12-01

The Iowa Flood Information System (IFIS) is a web-based platform developed by the Iowa Flood Center (IFC) to provide access to flood inundation maps, real-time flood conditions, flood forecasts both short-term and seasonal, flood-related data, information and interactive visualizations for communities in Iowa. The key element of the system's architecture is the notion of community. Locations of the communities, those near streams and rivers, define basin boundaries. The IFIS provides community-centric watershed and river characteristics, weather (rainfall) conditions, and streamflow data and visualization tools. Interactive interfaces allow access to inundation maps for different stage and return period values, and flooding scenarios with contributions from multiple rivers. Real-time and historical data of water levels, gauge heights, and rainfall conditions are available in the IFIS by streaming data from automated IFC bridge sensors, USGS stream gauges, NEXRAD radars, and NWS forecasts. Simple 2D and 3D interactive visualizations in the IFIS make the data more understandable to general public. Users are able to filter data sources for their communities and selected rivers. The data and information on IFIS is also accessible through web services and mobile applications. The IFIS is optimized for various browsers and screen sizes to provide access through multiple platforms including tablets and mobile devices. The IFIS includes a rainfall-runoff forecast model to provide a five-day flood risk estimate for around 500 communities in Iowa. Multiple view modes in the IFIS accommodate different user types from general public to researchers and decision makers by providing different level of tools and details. River view mode allows users to visualize data from multiple IFC bridge sensors and USGS stream gauges to follow flooding condition along a river. The IFIS will help communities make better-informed decisions on the occurrence of floods, and will alert communities in advance to help minimize damage of floods. This presentation provides an overview of the tools and interfaces in the IFIS developed to date to provide a platform for one-stop access to flood related data, visualizations, flood conditions, and forecast.

Flood Risk Management in Iowa through an Integrated Flood Information System

NASA Astrophysics Data System (ADS)

Demir, Ibrahim; Krajewski, Witold

2013-04-01

The Iowa Flood Information System (IFIS) is a web-based platform developed by the Iowa Flood Center (IFC) to provide access to flood inundation maps, real-time flood conditions, flood forecasts both short-term and seasonal, flood-related data, information and interactive visualizations for communities in Iowa. The key element of the system's architecture is the notion of community. Locations of the communities, those near streams and rivers, define basin boundaries. The IFIS provides community-centric watershed and river characteristics, weather (rainfall) conditions, and streamflow data and visualization tools. Interactive interfaces allow access to inundation maps for different stage and return period values, and flooding scenarios with contributions from multiple rivers. Real-time and historical data of water levels, gauge heights, and rainfall conditions are available in the IFIS by streaming data from automated IFC bridge sensors, USGS stream gauges, NEXRAD radars, and NWS forecasts. Simple 2D and 3D interactive visualizations in the IFIS make the data more understandable to general public. Users are able to filter data sources for their communities and selected rivers. The data and information on IFIS is also accessible through web services and mobile applications. The IFIS is optimized for various browsers and screen sizes to provide access through multiple platforms including tablets and mobile devices. The IFIS includes a rainfall-runoff forecast model to provide a five-day flood risk estimate for around 1100 communities in Iowa. Multiple view modes in the IFIS accommodate different user types from general public to researchers and decision makers by providing different level of tools and details. River view mode allows users to visualize data from multiple IFC bridge sensors and USGS stream gauges to follow flooding condition along a river. The IFIS will help communities make better-informed decisions on the occurrence of floods, and will alert communities in advance to help minimize damage of floods. This presentation provides an overview and live demonstration of the tools and interfaces in the IFIS developed to date to provide a platform for one-stop access to flood related data, visualizations, flood conditions, and forecast.

Access to Electronic Personal Health Records Among Patients With Multiple Chronic Conditions: A Secondary Data Analysis

PubMed Central

Falisi, Angela L; Finney Rutten, Lila J; Chou, Wen-Ying Sylvia; Patel, Vaishali; Moser, Richard P; Hesse, Bradford W

2017-01-01

Background In the United States, national incentives for offering access to electronic personal health records (ePHRs) through electronic means are geared toward creating a culture of patient engagement. One group of patients who stand to benefit from online access to ePHRs is the growing population with multiple chronic conditions (MCC). However, little is known about the current availability and use of ePHRs and patient portals among those managing MCC. Objective The aim was to determine the associations between number of chronic conditions and sociodemographic characteristics and usage of ePHRs, and to assess how the public’s use of ePHRs varies across subpopulations, including those with MCC. Methods This study used data collected from the 2014 Health Information National Trends Survey (HINTS), and assessed differences in use of ePHRs between those with and without MCC (N=3497) using multiple logistic regression techniques. Variables associated with health care systems (insurance status, having a regular provider) and patient-reported self-efficacy were included in the statistical models. Results Those with MCC (n=1555) had significantly higher odds of accessing their records three or more times in the past year compared to those reporting no chronic conditions (n=1050; OR 2.46, 95% CI 1.37-4.45), but the overall percentage of those with MCC using ePHRs remained low (371 of 1529 item respondents, 25.63% weighted). No difference in odds of accessing their records was found between those reporting one chronic condition (n=892) and those reporting none (n=1050; OR 1.02, 95% CI 0.66-1.58). Significant differences in odds of accessing ePHRs were seen between income and age groups (P<.001 and P=.05, respectively), and by whether respondents had a regular provider (P=.03). Conclusions We conclude that ePHRs provide a unique opportunity to enhance MCC patient self-management, but additional effort is needed to ensure that these patients are able to access their ePHRs. An increase in availability of patient access to their ePHRs may provide an opportunity to increase patient engagement and support self-management for all patients and especially those with MCC. PMID:28576755

Low- and High-Achieving Sixth-Grade Students' Access to Participation during Mathematics Discourse

ERIC Educational Resources Information Center

Lack, Brian; Swars, Susan Lee; Meyers, Barbara

2014-01-01

A descriptive, holistic, multiple-case methodology was applied to examine the nature of participation in discourse of two low- and two high-achieving grade 6 students while solving mathematical tasks in a standards-based classroom. Data collected via classroom observations and student interviews were analyzed through a multiple-cycle coding…

Systematic considerations in the area of multiple chemical sensitivity.

PubMed Central

Benignus, V A

1997-01-01

Many workers who speculate about multiple chemical sensitivity (MCS) have devised a large number of hypothetical constructs designed to explain the phenomena. Too often these are not logically connected to the larger body of scientific thought but instead appeal to ideas not documented in accessible literature and often appearing metaphysical in nature. PMID:9167984

Creating Multiple Pathways in the Arts: A New York City Case Study

ERIC Educational Resources Information Center

Maguire, Cindy; Mishook, Jacob; Garcia, Ivonne; de Gaillande, Genevieve

2013-01-01

Increasingly, education policy makers understand the importance of students and families having access to a range of high quality educational opportunities inside and outside of school, 365 days a year. This paper explores the concept of multiple pathways in arts education to further conceptualize and build upon such opportunities, inside and…

The Multiple Pendulum Problem via Maple[R

ERIC Educational Resources Information Center

Salisbury, K. L.; Knight, D. G.

2002-01-01

The way in which computer algebra systems, such as Maple, have made the study of physical problems of some considerable complexity accessible to mathematicians and scientists with modest computational skills is illustrated by solving the multiple pendulum problem. A solution is obtained for four pendulums with no restriction on the size of the…

An Adaptive Association Test for Multiple Phenotypes with GWAS Summary Statistics.

PubMed

Kim, Junghi; Bai, Yun; Pan, Wei

2015-12-01

We study the problem of testing for single marker-multiple phenotype associations based on genome-wide association study (GWAS) summary statistics without access to individual-level genotype and phenotype data. For most published GWASs, because obtaining summary data is substantially easier than accessing individual-level phenotype and genotype data, while often multiple correlated traits have been collected, the problem studied here has become increasingly important. We propose a powerful adaptive test and compare its performance with some existing tests. We illustrate its applications to analyses of a meta-analyzed GWAS dataset with three blood lipid traits and another with sex-stratified anthropometric traits, and further demonstrate its potential power gain over some existing methods through realistic simulation studies. We start from the situation with only one set of (possibly meta-analyzed) genome-wide summary statistics, then extend the method to meta-analysis of multiple sets of genome-wide summary statistics, each from one GWAS. We expect the proposed test to be useful in practice as more powerful than or complementary to existing methods. © 2015 WILEY PERIODICALS, INC.

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

NASA Astrophysics Data System (ADS)

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.

Baseband-processed SS-TDMA communication system architecture and design concepts

NASA Technical Reports Server (NTRS)

Attwood, S.; Sabourin, D.

1982-01-01

The architecture and system design for a commercial satellite communications system planned for the 1990's was developed by Motorola for NASA's Lewis Research Center. The system provides data communications between individual users via trunking and customer premises service terminals utilizing a central switching satellite operating in a time-division multiple-access (TDMA) mode. The major elements of the design incorporating baseband processing include: demand-assigned multiple access reservation protocol, spectral utilization, system synchronization, modulation technique and forward error control implementation. Motorola's baseband processor design, which is being proven in a proof-of-concept advanced technology development, will perform data regeneration and message routing for individual users on-board the spacecraft.

Access to Care and Satisfaction Among Health Center Patients With Chronic Conditions.

PubMed

Shi, Leiyu; Lee, De-Chih; Haile, Geraldine Pierre; Liang, Hailun; Chung, Michelle; Sripipatana, Alek

This study examined access to care and satisfaction among health center patients with chronic conditions. Data for this study were obtained from the 2009 Health Center Patient Survey. Dependent variables of interest included 5 measures of access to and satisfaction with care, whereas the main independent variable was number of chronic conditions. Results of bivariate analysis and multiple logistic regressions showed that patients with chronic conditions had significantly higher odds of reporting access barriers than those without chronic conditions. Our results suggested that additional efforts and resources are necessary to address the needs of health center patients with chronic conditions.

Accelerating global access to plant diversity information.

PubMed

Lughadha, Eimear Nic; Miller, Chuck

2009-11-01

Botanic gardens play key roles in the development and dissemination of plant information resources. Drivers for change have included progress in information technology, growing public expectations of electronic access and international conservation policy. Great advances have been made in the quantity, quality and accessibility of plant information in digital form and the extent to which information from multiple providers can be accessed through a single portal. However, significant challenges remain to be addressed in making botanic gardens resources maximally accessible and impactful, not least the overwhelming volume of material which still awaits digitisation. The year 2010 represents an opportunity for botanic gardens to showcase their collaborative achievements in delivery of electronic plant information and reinforce their relevance to pressing environmental issues.

Miscarriage - Multiple Languages

MedlinePlus

... Management of Miscarriage Aftercare Instructions - English ... updates Subscribe to RSS Follow us Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players MedlinePlus Connect for EHRs For ...

Origin and Reticulate Evolutionary Process of Wheatgrass Elymus trachycaulus (Triticeae: Poaceae)

PubMed Central

Zuo, Hongwei; Wu, Panpan; Wu, Dexiang; Sun, Genlou

2015-01-01

To study origin and evolutionary dynamics of tetraploid Elymus trachycaulus that has been cytologically defined as containing StH genomes, thirteen accessions of E. trachycaulus were analyzed using two low-copy nuclear gene Pepc (phosphoenolpyruvate carboxylase) and Rpb2 (the second largest subunit of RNA polymerase II), and one chloroplast region trnL–trnF (spacer between the tRNA Leu (UAA) gene and the tRNA-Phe (GAA) gene). Our chloroplast data indicated that Pseudoroegneria (St genome) was the maternal donor of E. trachycaulus. Rpb2 data indicated that the St genome in E. trachycaulus was originated from either P. strigosa, P. stipifolia, P. spicata or P. geniculate. The Hordeum (H genome)-like sequences of E. trachycaulus are polyphyletic in the Pepc tree, suggesting that the H genome in E. trachycaulus was contributed by multiple sources, whether due to multiple origins or introgression resulting from subsequent hybridization. Failure to recovering St copy of Pepc sequence in most accessions of E. trachycaulus might be caused by genome convergent evolution in allopolyploids. Multiple copies of H-like Pepc sequence from each accession with relative large deletions and insertions might be caused by either instability of Pepc sequence in H- genome or incomplete concerted evolution. Our results highlighted complex evolutionary history of E. trachycaulus. PMID:25946188

Performance Enhancement of MC-CDMA System through Novel Sensitive Bit Algorithm Aided Turbo Multi User Detection

PubMed Central

Kumaravel, Rasadurai; Narayanaswamy, Kumaratharan

2015-01-01

Multi carrier code division multiple access (MC-CDMA) system is a promising multi carrier modulation (MCM) technique for high data rate wireless communication over frequency selective fading channels. MC-CDMA system is a combination of code division multiple access (CDMA) and orthogonal frequency division multiplexing (OFDM). The OFDM parts reduce multipath fading and inter symbol interference (ISI) and the CDMA part increases spectrum utilization. Advantages of this technique are its robustness in case of multipath propagation and improve security with the minimize ISI. Nevertheless, due to the loss of orthogonality at the receiver in a mobile environment, the multiple access interference (MAI) appears. The MAI is one of the factors that degrade the bit error rate (BER) performance of MC-CDMA system. The multiuser detection (MUD) and turbo coding are the two dominant techniques for enhancing the performance of the MC-CDMA systems in terms of BER as a solution of overcome to MAI effects. In this paper a low complexity iterative soft sensitive bits algorithm (SBA) aided logarithmic-Maximum a-Posteriori algorithm (Log MAP) based turbo MUD is proposed. Simulation results show that the proposed method provides better BER performance with low complexity decoding, by mitigating the detrimental effects of MAI. PMID:25714917

Multi-static networked 3D ladar for surveillance and access control

NASA Astrophysics Data System (ADS)

Wang, Y.; Ogirala, S. S. R.; Hu, B.; Le, Han Q.

2007-04-01

A theoretical design and simulation of a 3D ladar system concept for surveillance, intrusion detection, and access control is described. It is a non-conventional system architecture that consists of: i) multi-static configuration with an arbitrarily scalable number of transmitters (Tx's) and receivers (Rx's) that form an optical wireless code-division-multiple-access (CDMA) network, and ii) flexible system architecture with modular plug-and-play components that can be deployed for any facility with arbitrary topology. Affordability is a driving consideration; and a key feature for low cost is an asymmetric use of many inexpensive Rx's in conjunction with fewer Tx's, which are generally more expensive. The Rx's are spatially distributed close to the surveyed area for large coverage, and capable of receiving signals from multiple Tx's with moderate laser power. The system produces sensing information that scales as NxM, where N, M are the number of Tx's and Rx's, as opposed to linear scaling ~N in non-network system. Also, for target positioning, besides laser pointing direction and time-of-flight, the algorithm includes multiple point-of-view image fusion and triangulation for enhanced accuracy, which is not applicable to non-networked monostatic ladars. Simulation and scaled model experiments on some aspects of this concept are discussed.

Self-organizing feature maps for dynamic control of radio resources in CDMA microcellular networks

NASA Astrophysics Data System (ADS)

Hortos, William S.

1998-03-01

The application of artificial neural networks to the channel assignment problem for cellular code-division multiple access (CDMA) cellular networks has previously been investigated. CDMA takes advantage of voice activity and spatial isolation because its capacity is only interference limited, unlike time-division multiple access (TDMA) and frequency-division multiple access (FDMA) where capacities are bandwidth-limited. Any reduction in interference in CDMA translates linearly into increased capacity. To satisfy the high demands for new services and improved connectivity for mobile communications, microcellular and picocellular systems are being introduced. For these systems, there is a need to develop robust and efficient management procedures for the allocation of power and spectrum to maximize radio capacity. Topology-conserving mappings play an important role in the biological processing of sensory inputs. The same principles underlying Kohonen's self-organizing feature maps (SOFMs) are applied to the adaptive control of radio resources to minimize interference, hence, maximize capacity in direct-sequence (DS) CDMA networks. The approach based on SOFMs is applied to some published examples of both theoretical and empirical models of DS/CDMA microcellular networks in metropolitan areas. The results of the approach for these examples are informally compared to the performance of algorithms, based on Hopfield- Tank neural networks and on genetic algorithms, for the channel assignment problem.

Unified double- and single-sided homogeneous Green’s function representations

PubMed Central

van der Neut, Joost; Slob, Evert

2016-01-01

In wave theory, the homogeneous Green’s function consists of the impulse response to a point source, minus its time-reversal. It can be represented by a closed boundary integral. In many practical situations, the closed boundary integral needs to be approximated by an open boundary integral because the medium of interest is often accessible from one side only. The inherent approximations are acceptable as long as the effects of multiple scattering are negligible. However, in case of strongly inhomogeneous media, the effects of multiple scattering can be severe. We derive double- and single-sided homogeneous Green’s function representations. The single-sided representation applies to situations where the medium can be accessed from one side only. It correctly handles multiple scattering. It employs a focusing function instead of the backward propagating Green’s function in the classical (double-sided) representation. When reflection measurements are available at the accessible boundary of the medium, the focusing function can be retrieved from these measurements. Throughout the paper, we use a unified notation which applies to acoustic, quantum-mechanical, electromagnetic and elastodynamic waves. We foresee many interesting applications of the unified single-sided homogeneous Green’s function representation in holographic imaging and inverse scattering, time-reversed wave field propagation and interferometric Green’s function retrieval. PMID:27436983

Unified double- and single-sided homogeneous Green's function representations

NASA Astrophysics Data System (ADS)

Wapenaar, Kees; van der Neut, Joost; Slob, Evert

2016-06-01

In wave theory, the homogeneous Green's function consists of the impulse response to a point source, minus its time-reversal. It can be represented by a closed boundary integral. In many practical situations, the closed boundary integral needs to be approximated by an open boundary integral because the medium of interest is often accessible from one side only. The inherent approximations are acceptable as long as the effects of multiple scattering are negligible. However, in case of strongly inhomogeneous media, the effects of multiple scattering can be severe. We derive double- and single-sided homogeneous Green's function representations. The single-sided representation applies to situations where the medium can be accessed from one side only. It correctly handles multiple scattering. It employs a focusing function instead of the backward propagating Green's function in the classical (double-sided) representation. When reflection measurements are available at the accessible boundary of the medium, the focusing function can be retrieved from these measurements. Throughout the paper, we use a unified notation which applies to acoustic, quantum-mechanical, electromagnetic and elastodynamic waves. We foresee many interesting applications of the unified single-sided homogeneous Green's function representation in holographic imaging and inverse scattering, time-reversed wave field propagation and interferometric Green's function retrieval.

Using Multidisciplinary Focus Groups to Inform the Development of mI SMART: A Nurse-Led Technology Intervention for Multiple Chronic Conditions

PubMed Central

Theeke, Laurie A.; Theeke, Elliott; Mallow, Brian K.

2016-01-01

Used as integrated tools, technology may improve the ability of healthcare providers to improve access and outcomes of care. Little is known about healthcare teams' preferences in using such technology. This paper reports the findings from focus groups aimed at evaluating a newly developed primary care technology platform. Focus groups were completed in academic, outpatient, and community settings. Focus groups were attended by 37 individuals. The participants included professionals from multiple disciplines. Both prescribing (N = 8) and nonprescribing healthcare team members (n = 21) completed the focus groups and survey. The majority were practicing for more than 20 years (44.8%) in an outpatient clinic (62%) for 20–40 hours per week (37.9%). Providers identified perceived obstacles of patient use as ability, willingness, and time. System obstacles were identified as lack of integration, lack of reimbursement, and cost. The positive attributes of the developed system were capability for virtual visits, readability, connectivity, user-friendliness, ability to capture biophysical measures, enhanced patient access, and incorporation of multiple technologies. Providers suggested increasing capability for biophysical and symptom monitoring for more common chronic conditions. Technology interventions have the potential to improve access and outcomes but will not be successful without the input of users. PMID:27504199

The Impacts of Using a Collaborative Evaluation Approach in Higher Education: A Case Study of Local YMCAs Providing College Access Services

ERIC Educational Resources Information Center

Campbell, Johnavae E.

2013-01-01

This dissertation offers a case study of the YMCA of the USA's pilot Higher Education Service Project (YHESP) with 61 local YMCAs on how the collaborative evaluation approach functioned to facilitate an organizational culture around evaluation and reinvention strategies of YMCAs as college access service providers. Multiple data collection sources…

Access to English Language Acquisition in Ghana Schools for the Deaf: Are the Deaf Students Handicapped?

ERIC Educational Resources Information Center

Obosu, Gideon Kwesi; Opoku-Asare, Nana Afia; Deku, Prosper

2016-01-01

This paper primarily discusses the challenges deaf students in Ghana are likely to grapple with as they access education provided for them in English language. The arguments discussed in this paper are supported by findings from a multiple site case study of five Schools for the Deaf purposively sampled from four regions of Ghana. Observations…

Health Service Access across Racial/Ethnic Groups of Children in the Child Welfare System

ERIC Educational Resources Information Center

Wells, Rebecca; Hillemeier, Marianne M.; Bai, Yu; Belue, Rhonda

2009-01-01

Objective: This study examined health service access among children of different racial/ethnic groups in the child welfare system in an attempt to identify and explain disparities. Methods: Data were from the National Survey of Child and Adolescent Well-Being (NSCAW). N for descriptive statistics = 2,505. N for multiple regression model = 537.…

Access-Control Schemes for Real-Time and Store-and-Forward Multiple-Access Communication Channels

DTIC Science & Technology

1980-01-01

N00014-78-C-0778 and SThe National Science Foundation under Grant NSF-EN677- 20799 Reproduction in whole or in part is permitted for any purpose of the...by the Naval Research Laboratory under Contract NRL-N00014-78-C-0778 and by the National Science Foundation under Grant NSF-ENG77- 20799 . Special thanks

Networking CD-ROMs: The Decision Maker's Guide to Local Area Network Solutions.

ERIC Educational Resources Information Center

Elshami, Ahmed M.

In an era when patrons want access to CD-ROM resources but few libraries can afford to buy multiple copies, CD-ROM local area networks (LANs) are emerging as a cost-effective way to provide shared access. To help librarians make informed decisions, this manual offers information on: (1) the basics of LANs, a "local area network primer";…

Multiple Motives, Conflicting Conceptions: Parsing the Contexts of Differentiated Access to Scientific Information in the Federal Government

ERIC Educational Resources Information Center

Oltmann, Shannon M.

2012-01-01

Scientific information, used by the U.S. federal government to formulate public policy in many arenas, is frequently contested and sometimes altered, blocked from publication, deleted from reports, or restricted in some way. This dissertation examines how and why restricted access to science policy (RASP) occurs through a comparative case study.…

Access and Use of New ICT Resources in Romanian Schools

ERIC Educational Resources Information Center

Onofrei, Smaranda Gabriela

2016-01-01

In the context of a digital age that marks all sectors of modern life, access and use of new technologies and the Internet by digital natives is an area with multiple speculations based on relatively little empirical research. It was noted that young people of this generation share a global common culture characterized more by their experience in…

Wireless Distribution Systems To Support Medical Response to Disasters

PubMed Central

Arisoylu, Mustafa; Mishra, Rajesh; Rao, Ramesh; Lenert, Leslie A.

2005-01-01

We discuss the design of multi-hop access networks with multiple gateways that supports medical response to disasters. We examine and implement protocols to ensure high bandwidth, robust, self-healing and secure wireless multi-hop access networks for extreme conditions. Address management, path setup, gateway discovery and selection protocols are described. Future directions and plans are also considered. PMID:16779171

Kenya's Constituency Development Fund, Free Secondary Education Policy, and Access to Secondary Education

ERIC Educational Resources Information Center

Nzuki, Charles Kyalo

2018-01-01

The effects of the Constituency Development Fund (CDF) and the Free Secondary Education Policy (FSEP) on access to secondary school education in Kenya's Yatta sub-county have not been adequately explored in available public policy literature. Hence, this qualitative multiple-case study was designed to understand the effects of the 2 policies on…

The Role of Women's Colleges and Universities in Providing Access to Postsecondary Education

ERIC Educational Resources Information Center

Renn, Kristen A.

2017-01-01

Based on a qualitative, comparative, multiple case study of the contributions and status of 21st century women's colleges and universities, this article analyzes the topic of women's access to postsecondary education in ten nations. Despite decreasing numbers of women-only institutions in some regions (e.g., North America), the sector is growing…

International Cancer Genome Consortium Data Portal--a one-stop shop for cancer genomics data.

PubMed

Zhang, Junjun; Baran, Joachim; Cros, A; Guberman, Jonathan M; Haider, Syed; Hsu, Jack; Liang, Yong; Rivkin, Elena; Wang, Jianxin; Whitty, Brett; Wong-Erasmus, Marie; Yao, Long; Kasprzyk, Arek

2011-01-01

The International Cancer Genome Consortium (ICGC) is a collaborative effort to characterize genomic abnormalities in 50 different cancer types. To make this data available, the ICGC has created the ICGC Data Portal. Powered by the BioMart software, the Data Portal allows each ICGC member institution to manage and maintain its own databases locally, while seamlessly presenting all the data in a single access point for users. The Data Portal currently contains data from 24 cancer projects, including ICGC, The Cancer Genome Atlas (TCGA), Johns Hopkins University, and the Tumor Sequencing Project. It consists of 3478 genomes and 13 cancer types and subtypes. Available open access data types include simple somatic mutations, copy number alterations, structural rearrangements, gene expression, microRNAs, DNA methylation and exon junctions. Additionally, simple germline variations are available as controlled access data. The Data Portal uses a web-based graphical user interface (GUI) to offer researchers multiple ways to quickly and easily search and analyze the available data. The web interface can assist in constructing complicated queries across multiple data sets. Several application programming interfaces are also available for programmatic access. Here we describe the organization, functionality, and capabilities of the ICGC Data Portal.

Despite Increased Insurance Coverage, Nonwhite Sexual Minorities Still Experience Disparities In Access To Care.

PubMed

Hsieh, Ning; Ruther, Matt

2017-10-01

Previous studies suggest that members of sexual minority groups have poorer access to health services than heterosexuals. However, few studies have examined how sexual orientation interacts with gender and race to affect health care experience. Moreover, little is known about the role in health care disparities played by economic strains such as unemployment and poverty, which may result from prejudice and discrimination based on sexual orientation. Using data for 2013-15 from the National Health Interview Survey, we found that most members of sexual minority groups no longer have higher uninsurance rates than heterosexuals, but many continue to experience poorer access to high-quality care. Gay nonwhite men, bisexual white women, and bisexual and lesbian nonwhite women are disadvantaged in multiple aspects of access, compared to straight white men. Only some of these disparities are attributable to economic factors, which implies that noneconomic barriers to care are substantial. Our results suggest that the intersection of multiple social identities can reveal important gaps in health care experience. Making culturally sensitive services available may be key to closing the gaps. Project HOPE—The People-to-People Health Foundation, Inc.

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

NASA Astrophysics Data System (ADS)

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

2015-12-01

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

Optimizing multiple-choice tests as tools for learning.

PubMed

Little, Jeri L; Bjork, Elizabeth Ligon

2015-01-01

Answering multiple-choice questions with competitive alternatives can enhance performance on a later test, not only on questions about the information previously tested, but also on questions about related information not previously tested-in particular, on questions about information pertaining to the previously incorrect alternatives. In the present research, we assessed a possible explanation for this pattern: When multiple-choice questions contain competitive incorrect alternatives, test-takers are led to retrieve previously studied information pertaining to all of the alternatives in order to discriminate among them and select an answer, with such processing strengthening later access to information associated with both the correct and incorrect alternatives. Supporting this hypothesis, we found enhanced performance on a later cued-recall test for previously nontested questions when their answers had previously appeared as competitive incorrect alternatives in the initial multiple-choice test, but not when they had previously appeared as noncompetitive alternatives. Importantly, however, competitive alternatives were not more likely than noncompetitive alternatives to be intruded as incorrect responses, indicating that a general increased accessibility for previously presented incorrect alternatives could not be the explanation for these results. The present findings, replicated across two experiments (one in which corrective feedback was provided during the initial multiple-choice testing, and one in which it was not), thus strongly suggest that competitive multiple-choice questions can trigger beneficial retrieval processes for both tested and related information, and the results have implications for the effective use of multiple-choice tests as tools for learning.

On the Performance Evaluation of a MIMO-WCDMA Transmission Architecture for Building Management Systems.

PubMed

Tsampasis, Eleftherios; Gkonis, Panagiotis K; Trakadas, Panagiotis; Zahariadis, Theodοre

2018-01-08

The goal of this study was to investigate the performance of a realistic wireless sensor nodes deployment in order to support modern building management systems (BMSs). A three-floor building orientation is taken into account, where each node is equipped with a multi-antenna system while a central base station (BS) collects and processes all received information. The BS is also equipped with multiple antennas; hence, a multiple input-multiple output (MIMO) system is formulated. Due to the multiple reflections during transmission in the inner of the building, a wideband code division multiple access (WCDMA) physical layer protocol has been considered, which has already been adopted for third-generation (3G) mobile networks. Results are presented for various MIMO orientations, where the mean transmission power per node is considered as an output metric for a specific signal-to-noise ratio (SNR) requirement and number of resolvable multipath components. In the first set of presented results, the effects of multiple access interference on overall transmission power are highlighted. As the number of mobile nodes per floor or the requested transmission rate increases, MIMO systems of a higher order should be deployed in order to maintain transmission power at adequate levels. In the second set of results, a comparison is performed among transmission in diversity combining and spatial multiplexing mode, which clearly indicate that the first case is the most appropriate solution for indoor communications.

Evaluation of a palliative and hospice care telephone hotline for patients severely affected by multiple sclerosis and their caregivers.

PubMed

Strupp, J; Groebe, B; Knies, A; Mai, M; Voltz, R; Golla, H

2017-12-01

Palliative and hospice care (PHC) still mainly focuses on patients with cancer. In order to connect patients severely affected by multiple sclerosis (MS) and caregivers to PHC, a nationwide hotline was implemented to facilitate access to PHC. The hotline was designed in cooperation with the German Multiple Sclerosis Society. Self-disclosed information given by callers was documented using case-report forms supplemented by personal notes. Data were analysed descriptively. A total of 222 calls were documented in 27 months. The patients' mean age was 51.12 years (range 27-84 years) and mean illness duration was 18 years (range 1 month to 50 years). Inquiries included information on PHC (28.8%) and access to PHC (due to previous refusal of PHC, 5.4%), general care for MS (36.1%), adequate housing (9.0%) and emotional support in crisis (4.5%). A total of 31.1% of callers reported 'typical' palliative symptoms (e.g. pain, 88.4%), 50.5% reported symptoms evolving from MS and 35.6% reported psychosocial problems. For 67 callers (30.2%), PHC services were recommended as indicated. The hotline provided insight into the needs and problems of patients severely affected by MS and their caregivers, some of which may be met by PHC. Future follow-up calls will demonstrate if the hotline helped to improve access to PHC beyond providing information. Overall, the hotline seemed to be easily accessible for patients severely affected by MS whose mobility is limited. © 2017 EAN.

Multiple memory stores and operant conditioning: a rationale for memory's complexity.

PubMed

Meeter, Martijn; Veldkamp, Rob; Jin, Yaochu

2009-02-01

Why does the brain contain more than one memory system? Genetic algorithms can play a role in elucidating this question. Here, model animals were constructed containing a dorsal striatal layer that controlled actions, and a ventral striatal layer that controlled a dopaminergic learning signal. Both layers could gain access to three modeled memory stores, but such access was penalized as energy expenditure. Model animals were then selected on their fitness in simulated operant conditioning tasks. Results suggest that having access to multiple memory stores and their representations is important in learning to regulate dopamine release, as well as in contextual discrimination. For simple operant conditioning, as well as stimulus discrimination, hippocampal compound representations turned out to suffice, a counterintuitive result given findings that hippocampal lesions tend not to affect performance in such tasks. We argue that there is in fact evidence to support a role for compound representations and the hippocampus in even the simplest conditioning tasks.

Performance of the Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the input/output (I/O) needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. This interface conceals the parallism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. Initial experiments, reported in this paper, indicate that Galley is capable of providing high-performance 1/O to applications the applications that rely on them. In Section 3 we describe that access data in patterns that have been observed to be common.

Acquisition of electroencephalographic data in a large regional hospital - Bringing the brain waves to the computer.

NASA Technical Reports Server (NTRS)

Low, M. D.; Baker, M.; Ferguson, R.; Frost, J. D., Jr.

1972-01-01

This paper describes a complete electroencephalographic acquisition and transmission system, designed to meet the needs of a large hospital with multiple critical care patient monitoring units. The system provides rapid and prolonged access to a centralized recording and computing area from remote locations within the hospital complex, and from locations in other hospitals and other cities. The system includes quick-on electrode caps, amplifier units and cable transmission for access from within the hospital, and EEG digitization and telephone transmission for access from other hospitals or cities.

Analyzing public inputs to multiple objective decisions on national forests using conjoint analysis

Treesearch

Donald F. Dennis

1998-01-01

Faced with multiple objectives, national forest managers and planners need a means to solicit and analyze public preferences and values. A conjoint ranking survey was designed to solicit public preferences for various levels of timber harvesting, wildlife habitats, hiking trails, snowmobile use, and off-road-vehicle (ORV) access on the Green Mountain National Forest....

A distributed data base management facility for the CAD/CAM environment

NASA Technical Reports Server (NTRS)

Balza, R. M.; Beaudet, R. W.; Johnson, H. R.

1984-01-01

Current/PAD research in the area of distributed data base management considers facilities for supporting CAD/CAM data management in a heterogeneous network of computers encompassing multiple data base managers supporting a variety of data models. These facilities include coordinated execution of multiple DBMSs to provide for administration of and access to data distributed across them.

Effects of a Voice Output Communication Aid on Interactions between Support Personnel and an Individual with Multiple Disabilities.

ERIC Educational Resources Information Center

Schepis, Maureen M.; Reid, Dennis H.

1995-01-01

A young adult with multiple disabilities (profound mental retardation, spastic quadriplegia, and visual impairment) was provided with a voice output communication aid (VOCA) which allowed communication through synthesized speech. Both educational and residential staff members interacted with the individual more frequently when she had access to…

Utilizing Spectrum Efficiently (USE)

DTIC Science & Technology

2011-02-28

18 4.8 Space-Time Coded Asynchronous DS - CDMA with Decentralized MAI Suppression: Performance and...numerical results. 4.8 Space-Time Coded Asynchronous DS - CDMA with Decentralized MAI Suppression: Performance and Spectral Efficiency In [60] multiple...supported at a given signal-to-interference ratio in asynchronous direct-sequence code-division multiple-access ( DS - CDMA ) sys- tems was examined. It was

Navigating Access and Maintaining Established Practice: Social Studies Teachers' Technology Integration at Three Florida Middle Schools

ERIC Educational Resources Information Center

Sheffield, Caroline

2011-01-01

This mixed methods multiple case study explored middle school social studies teachers' instructional use of digital technology at three suburban middle schools This mixed methods, multiple-case study explored middle school social studies teachers' instructional use of digital technology at three suburban middle schools in a large Florida school…

Touching Mercury in Community Media: Identifying Multiple Literacy Learning through Digital Arts Production

ERIC Educational Resources Information Center

Arndt, Angela E.

2011-01-01

Educational paradigm shifts call for 21st century learners to possess the knowledge, skills, abilities, values, and experiences associated with multiple forms of literacy in a participatory learning culture. Contemporary educational systems are slow to adapt. Outside of school, people have to be self-motivated and have access to resources in order…

Phylogeny and evolutionary histories of Pyrus L. revealed by phylogenetic trees and networks based on data from multiple DNA sequences

USDA-ARS?s Scientific Manuscript database

Reconstructing the phylogeny of Pyrus has been difficult due to the wide distribution of the genus and lack of informative data. In this study, we collected 110 accessions representing 25 Pyrus species and constructed both phylogenetic trees and phylogenetic networks based on multiple DNA sequence d...

Logical optical line terminal technologies towards flexible and highly reliable metro- and access-integrated networks

NASA Astrophysics Data System (ADS)

Okamoto, Satoru; Sato, Takehiro; Yamanaka, Naoaki

2017-01-01

In this paper, flexible and highly reliable metro and access integrated networks with network virtualization and software defined networking technologies will be presented. Logical optical line terminal (L-OLT) technologies and active optical distribution networks (ODNs) are the key to introduce flexibility and high reliability into the metro and access integrated networks. In the Elastic Lambda Aggregation Network (EλAN) project which was started in 2012, a concept of the programmable optical line terminal (P-OLT) has been proposed. A role of the P-OLT is providing multiple network services that have different protocols and quality of service requirements by single OLT box. Accommodated services will be Internet access, mobile front-haul/back-haul, data-center access, and leased line. L-OLTs are configured within the P-OLT box to support the functions required for each network service. Multiple P-OLTs and programmable optical network units (P-ONUs) are connected by the active ODN. Optical access paths which have flexible capacity are set on the ODN to provide network services from L-OLT to logical ONUs (L-ONUs). The L-OLT to L-ONU path on the active ODN provides a logical connection. Therefore, introducing virtualization technologies becomes possible. One example is moving an L-OLT from one P-OLT to another P-OLT like a virtual machine. This movement is called L-OLT migration. The L-OLT migration provides flexible and reliable network functions such as energy saving by aggregating L-OLTs to a limited number of P-OLTs, and network wide optical access path restoration. Other L-OLT virtualization technologies and experimental results will be also discussed in the paper.

From continuing education to personal digital assistants: what do physical therapists need to support evidence-based practice in stroke management?

PubMed

Salbach, Nancy M; Veinot, Paula; Jaglal, Susan B; Bayley, Mark; Rolfe, Danielle

2011-08-01

Understanding how to structure educational interventions and resources to facilitate physical therapists' application of the research literature is required. The objective of this study was to explore physical therapists' preferences for strategies to facilitate their access to, evaluation and implementation of the stroke research literature in clinical practice. In-depth, qualitative telephone interviews were conducted with 23 physical therapists who treat people with stroke in Ontario, Canada and who had participated in a previous survey on evidence-based practice. Data were analysed using a constant comparative approach to identify emergent themes. Participants preferred online access to research summaries or systematic reviews to save time to filter and critique research articles. To enable access in the workplace, an acceptable computer-to-staff ratio, permission to access web sites and protected work time were suggested. Participants considered personal digital assistants as excellent tools for quick access to online resources but were unsure of their advantage over a desktop computer. Therapists favoured use of non-technical language, glossaries of research terms and quality ratings of studies to ease understanding and appraisal. Teleconferencing or videoconferencing overcame geographical but not scheduling barriers to accessing education. To achieve behaviour change in clinical practice, therapists preferred multiple interactive, face-to-face education sessions in a group format, with opportunities for case-based learning and practice of new skills. Physical therapists prefer technology-assisted access to resources and education and favour attending multiple interactive, expert-facilitated education sessions incorporating opportunities for case-based learning and practice of new skills to change behaviour related to evidence-based practice. © 2010 Blackwell Publishing Ltd.

Providing Access and Visualization to Global Cloud Properties from GEO Satellites

NASA Astrophysics Data System (ADS)

Chee, T.; Nguyen, L.; Minnis, P.; Spangenberg, D.; Palikonda, R.; Ayers, J. K.

2015-12-01

Providing public access to cloud macro and microphysical properties is a key concern for the NASA Langley Research Center Cloud and Radiation Group. This work describes a tool and method that allows end users to easily browse and access cloud information that is otherwise difficult to acquire and manipulate. The core of the tool is an application-programming interface that is made available to the public. One goal of the tool is to provide a demonstration to end users so that they can use the dynamically generated imagery as an input into their own work flows for both image generation and cloud product requisition. This project builds upon NASA Langley Cloud and Radiation Group's experience with making real-time and historical satellite cloud product imagery accessible and easily searchable. As we see the increasing use of virtual supply chains that provide additional value at each link there is value in making satellite derived cloud product information available through a simple access method as well as allowing users to browse and view that imagery as they need rather than in a manner most convenient for the data provider. Using the Open Geospatial Consortium's Web Processing Service as our access method, we describe a system that uses a hybrid local and cloud based parallel processing system that can return both satellite imagery and cloud product imagery as well as the binary data used to generate them in multiple formats. The images and cloud products are sourced from multiple satellites and also "merged" datasets created by temporally and spatially matching satellite sensors. Finally, the tool and API allow users to access information that spans the time ranges that our group has information available. In the case of satellite imagery, the temporal range can span the entire lifetime of the sensor.

Effects of semantic context on access to words of low imageability in deep-phonological dysphasia: a treatment case study.

PubMed

McCarthy, Laura Mary; Kalinyak-Fliszar, Michelene; Kohen, Francine; Martin, Nadine

2017-01-01

Deep dysphasia is a relatively rare subcategory of aphasia, characterised by word repetition impairment and a profound auditory-verbal short-term memory (STM) limitation. Repetition of words is better than nonwords (lexicality effect) and better for high-image than low-image words (imageability effect). Another related language impairment profile is phonological dysphasia, which includes all of the characteristics of deep dysphasia except for the occurrence of semantic errors in single word repetition. The overlap in symptoms of deep and phonological dysphasia has led to the hypothesis that they share the same root cause, impaired maintenance of activated representation of words, but that they differ in severity of that impairment, with deep dysphasia being more severe. We report a single-subject multiple baseline, multiple probe treatment study of a person who presented with a pattern of repetition that was consistent with the continuum of deep-phonological dysphasia: imageability and lexicality effects in repetition of single and multiple words and semantic errors in repetition of multiple-word utterances. The aim of this treatment study was to improve access to and repetition of low-imageability words by embedding them in modifier-noun phrases that enhanced their imageability. The treatment involved repetition of abstract noun pairs. We created modifier-abstract noun phrases that increased the semantic and syntactic cohesiveness of the words in the pair. For example, the phrases "long distance" and "social exclusion" were developed to improve repetition of the abstract pair "distance-exclusion". The goal of this manipulation was to increase the probability of accessing lexical and semantic representations of abstract words in repetition by enriching their semantic -syntactic context. We predicted that this increase in accessibility would be maintained when the words were repeated as pairs, but without the contextual phrase. Treatment outcomes indicated that increasing the semantic and syntactic cohesiveness of low-imageability and low-frequency words later improved this participant's ability to repeat those words when presented in isolation. This treatment approach to improving access to abstract word pairs for repetition was successful for our participant with phonological dysphasia. The approach exemplifies the potential value in manipulating linguistic characteristics of stimuli in ways that improve access between phonological and lexical-semantic levels of representation. Additionally, this study demonstrates how principles of a cognitive model of word processing can be used to guide treatment of word processing impairments in aphasia.

Hierarchy Bayesian model based services awareness of high-speed optical access networks

NASA Astrophysics Data System (ADS)

Bai, Hui-feng

2018-03-01

As the speed of optical access networks soars with ever increasing multiple services, the service-supporting ability of optical access networks suffers greatly from the shortage of service awareness. Aiming to solve this problem, a hierarchy Bayesian model based services awareness mechanism is proposed for high-speed optical access networks. This approach builds a so-called hierarchy Bayesian model, according to the structure of typical optical access networks. Moreover, the proposed scheme is able to conduct simple services awareness operation in each optical network unit (ONU) and to perform complex services awareness from the whole view of system in optical line terminal (OLT). Simulation results show that the proposed scheme is able to achieve better quality of services (QoS), in terms of packet loss rate and time delay.

Patterns of perceived barriers to medical care in older adults: a latent class analysis.

PubMed

Thorpe, Joshua M; Thorpe, Carolyn T; Kennelty, Korey A; Pandhi, Nancy

2011-08-03

This study examined multiple dimensions of healthcare access in order to develop a typology of perceived barriers to healthcare access in community-dwelling elderly. Secondary aims were to define distinct classes of older adults with similar perceived healthcare access barriers and to examine predictors of class membership to identify risk factors for poor healthcare access. A sample of 5,465 community-dwelling elderly was drawn from the 2004 wave of the Wisconsin Longitudinal Study. Perceived barriers to healthcare access were measured using items from the Group Health Association of America Consumer Satisfaction Survey. We used latent class analysis to assess the constellation of items measuring perceived barriers in access and multinomial logistic regression to estimate how risk factors affected the probability of membership in the latent barrier classes. Latent class analysis identified four classes of older adults. Class 1 (75% of sample) consisted of individuals with an overall low level of risk for perceived access problems (No Barriers). Class 2 (5%) perceived problems with the availability/accessibility of healthcare providers such as specialists or mental health providers (Availability/Accessibility Barriers). Class 3 (18%) perceived problems with how well their providers' operations arise organized to accommodate their needs and preferences (Accommodation Barriers). Class 4 (2%) perceived problems with all dimension of access (Severe Barriers). Results also revealed that healthcare affordability is a problem shared by members of all three barrier groups, suggesting that older adults with perceived barriers tend to face multiple, co-occurring problems. Compared to those classified into the No Barriers group, those in the Severe Barrier class were more likely to live in a rural county, have no health insurance, have depressive symptomatology, and speech limitations. Those classified into the Availability/Accessibility Barriers group were more likely to live in rural and micropolitan counties, have depressive symptomatology, more chronic conditions, and hearing limitations. Those in the Accommodation group were more likely to have depressive symptomatology and cognitive limitations. The current study identified a typology of perceived barriers in healthcare access in older adults. The identified risk factors for membership in perceived barrier classes could potentially assist healthcare organizations and providers with targeting polices and interventions designed to improve access in their most vulnerable older adult populations, particularly those in rural areas, with functional disabilities, or in poor mental health.

Household trends in access to improved water sources and sanitation facilities in Vietnam and associated factors: findings from the Multiple Indicator Cluster Surveys, 2000–2011

PubMed Central

Tuyet-Hanh, Tran Thi; Lee, Jong-Koo; Oh, Juhwan; Van Minh, Hoang; Ou Lee, Chul; Hoan, Le Thi; Nam, You-Seon; Long, Tran Khanh

2016-01-01

Background Despite progress made by the Millennium Development Goal (MDG) number 7.C, Vietnam still faces challenges with regard to the provision of access to safe drinking water and basic sanitation. Objective This paper describes household trends in access to improved water sources and sanitation facilities separately, and analyses factors associated with access to improved water sources and sanitation facilities in combination. Design Secondary data from the Vietnam Multiple Indicator Cluster Survey in 2000, 2006, and 2011 were analyzed. Descriptive statistics and tests of significance describe trends over time in access to water and sanitation by location, demographic and socio-economic factors. Binary logistic regressions (2000, 2006, and 2011) describe associations between access to water and sanitation, and geographic, demographic, and socio-economic factors. Results There have been some outstanding developments in access to improved water sources and sanitation facilities from 2000 to 2011. In 2011, the proportion of households with access to improved water sources and sanitation facilities reached 90% and 77%, respectively, meeting the 2015 MDG targets for safe drinking water and basic sanitation set at 88% and 75%, respectively. However, despite these achievements, in 2011, only 74% of households overall had access to combined improved drinking water and sanitation facilities. There were also stark differences between regions. In 2011, only 47% of households had access to both improved water and sanitation facilities in the Mekong River Delta compared with 94% in the Red River Delta. In 2011, households in urban compared to rural areas were more than twice as likely (odds ratio [OR]: 2.2; 95% confidence interval [CI]: 1.9–2.5) to have access to improved water and sanitation facilities in combination, and households in the highest compared with the lowest wealth quintile were over 40 times more likely (OR: 42.3; 95% CI: 29.8–60.0). Conclusions More efforts are required to increase household access to both improved water and sanitation facilities in the Mekong River Delta, South East and Central Highlands regions of Vietnam. There is also a need to address socio-economic factors associated with inadequate access to improved sanitation facilities. PMID:26950563

A study and experiment plan for digital mobile communication via satellite

NASA Technical Reports Server (NTRS)

Jones, J. J.; Craighill, E. J.; Evans, R. G.; Vincze, A. D.; Tom, N. N.

1978-01-01

The viability of mobile communications is examined within the context of a frequency division multiple access, single channel per carrier satellite system emphasizing digital techniques to serve a large population of users. The intent is to provide the mobile users with a grade of service consistant with the requirements for remote, rural (perhaps emergency) voice communications, but which approaches toll quality speech. A traffic model is derived on which to base the determination of the required maximum number of satellite channels to provide the anticipated level of service. Various voice digitalization and digital modulation schemes are reviewed along with a general link analysis of the mobile system. Demand assignment multiple access considerations and analysis tradeoffs are presented. Finally, a completed configuration is described.

Fiber-Bragg-Grating-Based Optical Code-Division Multiple Access Passive Optical Network Using Dual-Baseband Modulation Scheme

NASA Astrophysics Data System (ADS)

Lin, Wen-Piao; Wu, He-Long

2005-08-01

We propose a fiber-Bragg-grating (FBG)-based optical code-division multiple access passive optical network (OCDMA-PON) using a dual-baseband modulation scheme. A mathematical model is developed to study the performance of this scheme. According to the analyzed results, this scheme can allow a tolerance of the spectral power distortion (SPD) ratio of 25% with a bit error rate (BER) of 10-9 when the modified pseudorandom noise (PN) code length is 16. Moreover, we set up a simulated system to evaluate the baseband and radio frequency (RF) band transmission characteristics. The simulation results demonstrate that our proposed OCDMA-PON can provide a cost-effective and scalable fiber-to-the-home solution.

Packet communications in satellites with multiple-beam antennas and signal processing

NASA Technical Reports Server (NTRS)

Davies, R.; Chethik, F.; Penick, M.

1980-01-01

A communication satellite with a multiple-beam antenna and onboard signal processing is considered for use in a 'message-switched' data relay system. The signal processor may incorporate demodulation, routing, storage, and remodulation of the data. A system user model is established and key functional elements for the signal processing are identified. With the throughput and delay requirements as the controlled variables, the hardware complexity, operational discipline, occupied bandwidth, and overall user end-to-end cost are estimated for (1) random-access packet switching; and (2) reservation-access packet switching. Other aspects of this network (eg, the adaptability to channel switched traffic requirements) are examined. For the given requirements and constraints, the reservation system appears to be the most attractive protocol.

A Simple Exact Error Rate Analysis for DS-CDMA with Arbitrary Pulse Shape in Flat Nakagami Fading

NASA Astrophysics Data System (ADS)

Rahman, Mohammad Azizur; Sasaki, Shigenobu; Kikuchi, Hisakazu; Harada, Hiroshi; Kato, Shuzo

A simple exact error rate analysis is presented for random binary direct sequence code division multiple access (DS-CDMA) considering a general pulse shape and flat Nakagami fading channel. First of all, a simple model is developed for the multiple access interference (MAI). Based on this, a simple exact expression of the characteristic function (CF) of MAI is developed in a straight forward manner. Finally, an exact expression of error rate is obtained following the CF method of error rate analysis. The exact error rate so obtained can be much easily evaluated as compared to the only reliable approximate error rate expression currently available, which is based on the Improved Gaussian Approximation (IGA).

MAI statistics estimation and analysis in a DS-CDMA system

NASA Astrophysics Data System (ADS)

Alami Hassani, A.; Zouak, M.; Mrabti, M.; Abdi, F.

2018-05-01

A primary limitation of Direct Sequence Code Division Multiple Access DS-CDMA link performance and system capacity is multiple access interference (MAI). To examine the performance of CDMA systems in the presence of MAI, i.e., in a multiuser environment, several works assumed that the interference can be approximated by a Gaussian random variable. In this paper, we first develop a new and simple approach to characterize the MAI in a multiuser system. In addition to statistically quantifying the MAI power, the paper also proposes a statistical model for both variance and mean of the MAI for synchronous and asynchronous CDMA transmission. We show that the MAI probability density function (PDF) is Gaussian for the equal-received-energy case and validate it by computer simulations.

NewProt - a protein engineering portal.

PubMed

Schwarte, Andreas; Genz, Maika; Skalden, Lilly; Nobili, Alberto; Vickers, Clare; Melse, Okke; Kuipers, Remko; Joosten, Henk-Jan; Stourac, Jan; Bendl, Jaroslav; Black, Jon; Haase, Peter; Baakman, Coos; Damborsky, Jiri; Bornscheuer, Uwe; Vriend, Gert; Venselaar, Hanka

2017-06-01

The NewProt protein engineering portal is a one-stop-shop for in silico protein engineering. It gives access to a large number of servers that compute a wide variety of protein structure characteristics supporting work on the modification of proteins through the introduction of (multiple) point mutations. The results can be inspected through multiple visualizers. The HOPE software is included to indicate mutations with possible undesired side effects. The Hotspot Wizard software is embedded for the design of mutations that modify a proteins' activity, specificity, or stability. The NewProt portal is freely accessible at http://newprot.cmbi.umcn.nl/ and http://newprot.fluidops.net/. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

D3: A Collaborative Infrastructure for Aerospace Design

NASA Technical Reports Server (NTRS)

Walton, Joan; Filman, Robert E.; Knight, Chris; Korsmeyer, David J.; Lee, Diana D.; Clancy, Daniel (Technical Monitor)

2001-01-01

DARWIN is a NASA developed, Internet-based system for enabling aerospace researchers to securely and remotely access and collaborate on the analysis of aerospace vehicle design data, primarily the results of wind-tunnel testing and numeric (e.g., computational fluid dynamics) model executions. DARWIN captures, stores and indexes data, manages derived knowledge (such as visualizations across multiple data sets) and provides an environment for designers to collaborate in the analysis of the results of testing. DARWIN is an interesting application because it supports high volumes of data, integrates multiple modalities of data display (e.g. images and data visualizations), and provides non-trivial access control mechanisms. DARWIN enables collaboration by allowing not only sharing visualizations of data, but also commentary about and view of data.

Performance analysis of quantum access network using code division multiple access model

NASA Astrophysics Data System (ADS)

Hu, Linxi; Yang, Can; He, Guangqiang

2017-06-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 61475099 and 61102053), the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices (Grant No. KF201405), the Open Fund of IPOC (BUPT) (Grant No. IPOC2015B004), and the Program of State Key Laboratory of Information Security (Grant No. 2016-MS-05).

Vocational Guidance for Equal Access and Opportunity for Girls and Women in Technical and Vocational Education. UNEVOC Studies in Technical and Vocational Education 6.

ERIC Educational Resources Information Center

Miller, Juliet V.; Vetter, Louise

A study examined the relevance of vocational information and guidance for the equal access of girls and women to technical/vocational education in the following countries: Argentina; India; Mexico; Republic of Korea; South Africa; Spain; Sweden; Turkey; United Arab Emirates; and Zambia. Case studies were conducted by using a multiple-strategy…

High Productivity Computing Systems Analysis and Performance

DTIC Science & Technology

2005-07-01

cubic grid Discrete Math Global Updates per second (GUP/S) RandomAccess Paper & Pencil Contact Bob Lucas (ISI) Multiple Precision none...can be found at the web site. One of the HPCchallenge codes, RandomAccess, is derived from the HPCS discrete math benchmarks that we released, and...Kernels Discrete Math … Graph Analysis … Linear Solvers … Signal Processi ng Execution Bounds Execution Indicators 6 Scalable Compact

State Public Policies and the Racial/Ethnic Stratification of College Access and Choice in the State of Maryland

ERIC Educational Resources Information Center

Perna, Laura W.; Steele, Patricia; Woda, Susan; Hibbert, Taifa

2005-01-01

This study uses descriptive analyses of data from multiple sources to examine changes during the 1990s in the racial/ethnic stratification of college access and choice in Maryland and to explore state public policies that may have influenced changes in the demand for and supply of higher education for students of different racial/ethnic groups…

Ease of Access to List Items in Short-Term Memory Depends on the Order of the Recognition Probes

ERIC Educational Resources Information Center

Lange, Elke B.; Cerella, John; Verhaeghen, Paul

2011-01-01

We report data from 4 experiments using a recognition design with multiple probes to be matched to specific study positions. Items could be accessed rapidly, independent of set size, when the test order matched the study order (forward condition). When the order of testing was random, backward, or in a prelearned irregular sequence (reordered…

Influence of Special Needs Education Policy on Access to Secondary School Education by Learners with Hearing Impairments in Nandi County, Kenya

ERIC Educational Resources Information Center

Muhombe, Joseph Andrew; Rop, Naftali K.; Ogola, Fredrick O.; Wesonga, Justus Nyongesa

2015-01-01

This study sought to examine influence of Special Needs Education Policy on access to secondary school education by learners with hearing impairments in Nandi County, Kenya. The study was informed by the Multiple Intelligences theory and the Dewey theory of Progressivism. The findings showed that majority of the respondents were aware of the…

Innovative Approaches Address Aging and Mental Health Needs in LGBTQ Communities.

PubMed

Hoy-Ellis, Charles P; Ator, Michael; Kerr, Christopher; Milford, Jessica

2016-01-01

LGBTQ older adults have higher levels of psychological distress as compared to older adults in general. They also experience multiple barriers to accessing equitable, culturally competent mental health and aging services because of their distinct histories and particular social contexts. This article discusses this lack of access to services, and highlights an innovative way mental health services are being delivered in LGBTQ communities.

Evaluating multiple dimensions of visitors' tradeoffs between access and crowding at Arches National Park using indifference curve analysis

Treesearch

Steven R. Lawson; Robert E. Manning

2001-01-01

Tradeoffs are an inherent part of many of the decisions faced by outdoor recreation managers. For example, decisions concerning the social carrying capacity of popular attraction sites involve tradeoffs between limiting visitor use to ensure a high quality experience and allowing high levels of visitor use to ensure that large numbers of visitors retain access to park...

People with Profound and Multiple Intellectual Disabilities Using Symbols to Control a Computer: Exploration of User Engagement and Supporter Facilitation

ERIC Educational Resources Information Center

Bunning, Karen; Kwiatkowska, Gosia; Weldin, Nick

2012-01-01

Computer usage features in everyday life for the majority of people in developed countries. Access is a problem for many users with intellectual disability. Action-research was conducted to develop and explore the potential of specially adapted, computer readable symbols for choosing and accessing media on a computer. Five people with profound and…

The effects of note-taking and trial transcript access on mock jury decisions in a complex civil trial.

PubMed

Horowitz, I A; ForsterLee, L

2001-08-01

Mock juries were either permitted to take notes or not and provided with access to the trial transcript during deliberations or were not given access. Juries viewed a videotape of a complex trial involving multiple plaintiffs. Note-taking juries were able to distinguish among differentially worthy plaintiffs when assigning awards while non note takers did not distinguish among the plaintiffs and allocated higher overall compensation. Note-taking was significantly more effective than access to trial transcripts in increasing jury competence. Note-taking juries appeared better able to recognize probative evidence and reject false lures than were non note-taking juries. Limits and implications of the present study were discussed.

Efficient accesses of data structures using processing near memory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jayasena, Nuwan S.; Zhang, Dong Ping; Diez, Paula Aguilera

Systems, apparatuses, and methods for implementing efficient queues and other data structures. A queue may be shared among multiple processors and/or threads without using explicit software atomic instructions to coordinate access to the queue. System software may allocate an atomic queue and corresponding queue metadata in system memory and return, to the requesting thread, a handle referencing the queue metadata. Any number of threads may utilize the handle for accessing the atomic queue. The logic for ensuring the atomicity of accesses to the atomic queue may reside in a management unit in the memory controller coupled to the memory wheremore » the atomic queue is allocated.« less

Multi-Mode, Multi-Antenna Software Defined Radar for Adaptive Tracking and Identification of Targets in Urban Environments

DTIC Science & Technology

2011-10-31

designs with code division multiple access ( CDMA ). Analog chirp filters were used to produce an up-chirp, which is used as a radar waveform, coupled with...signals. A potential shortcoming of CDMA techniques is that the addition of two signals will result in a non-constant amplitude signal which will be...of low-frequency A/ Ds . As an example for a multiple carrier signal all the received signals from the multiple carriers are aliased onto the

Synthesis of Polyheteroaromatic Compounds via Rhodium-Catalyzed Multiple C-H Bond Activation and Oxidative Annulation.

PubMed

Peng, Shiyong; Liu, Suna; Zhang, Sai; Cao, Shengyu; Sun, Jiangtao

2015-10-16

Polyheteroaromatic compounds are potential optoelectronic conjugated materials due to their electro- and photochemical properties. Transition-metal-catalyzed multiple C-H activation and sequential oxidative annulation allows rapidly assembling of those compounds from readily available starting materials. A rhodium-catalyzed cascade oxidative annulation of β-enamino esters or 4-aminocoumarins with internal alkynes is described to access those compounds, featuring multiple C-H/N-H bond cleavages and sequential C-C/C-N bond formations in one pot.

Study of advanced communications satellite systems based on SS-FDMA

NASA Technical Reports Server (NTRS)

Kiesling, J.

1980-01-01

A satellite communication system based on the use of a multiple, contiguous beam satellite antenna and frequency division multiple access (FDMA) is studied. Emphasis is on the evaluation of the feasibility of SS (satellite switching) FDMA technology, particularly the multiple, contiguous beam antenna, the onboard switch and channelization, and on methods to overcome the effects of severe Ka band fading caused by precipitation. This technology is evaluated and plans for technology development and evaluation are given. The application of SS-FDMA to domestic satellite communications is also evaluated. Due to the potentially low cost Earth stations, SS-FDMA is particularly attractive for thin route applications up to several hundred kilobits per second, and offers the potential for competing with terrestrial facilities at low data rates and over short routes. The onboard switch also provides added route flexibility for heavy route systems. The key beneficial SS-FDMA strategy is to simplify and thus reduce the cost of the direct access Earth station at the expense of increased satellite complexity.

Supporting Young Children with Multiple Disabilities: What Do We Know and What Do We Still Need to Learn?

ERIC Educational Resources Information Center

Horn, Eva; Kang, Jean

2012-01-01

Young children with multiple disabilities have unique needs and challenges. Many of these young children struggle to communicate their wants and needs, to freely move their body to access and engage their world, and to learn abstract concepts and ideas. Professionals and families working together must identify the individual supports each child…

The Value of Tuition Assistance Programs: A Multiple Exploratory Case Study

ERIC Educational Resources Information Center

Tlapa, Margie

2017-01-01

Organizations invest billions annually in the form of Tuition Assistance Programs (TAP) with little knowledge as to the reasons why employees choose to participate. The purpose of this multiple exploratory case study was to explore the perceptions of employees with access to a TAP of at least $5,250 per year. Interviews were conducted with 17…

Ocean Variability Effects on Underwater Acoustic Communications

DTIC Science & Technology

2011-09-01

schemes for accessing wide frequency bands. Compared with OFDM schemes, the multiband MIMO transmission combined with time reversal processing...systems, or multiple- input/multiple-output ( MIMO ) systems, decision feedback equalization and interference cancellation schemes have been integrated...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 MIMO receiver also iterates channel estimation and symbol demodulation with

Optimized scheduling technique of null subcarriers for peak power control in 3GPP LTE downlink.

PubMed

Cho, Soobum; Park, Sang Kyu

2014-01-01

Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system.

Optimized Scheduling Technique of Null Subcarriers for Peak Power Control in 3GPP LTE Downlink

PubMed Central

Park, Sang Kyu

2014-01-01

Orthogonal frequency division multiple access (OFDMA) is a key multiple access technique for the long term evolution (LTE) downlink. However, high peak-to-average power ratio (PAPR) can cause the degradation of power efficiency. The well-known PAPR reduction technique, dummy sequence insertion (DSI), can be a realistic solution because of its structural simplicity. However, the large usage of subcarriers for the dummy sequences may decrease the transmitted data rate in the DSI scheme. In this paper, a novel DSI scheme is applied to the LTE system. Firstly, we obtain the null subcarriers in single-input single-output (SISO) and multiple-input multiple-output (MIMO) systems, respectively; then, optimized dummy sequences are inserted into the obtained null subcarrier. Simulation results show that Walsh-Hadamard transform (WHT) sequence is the best for the dummy sequence and the ratio of 16 to 20 for the WHT and randomly generated sequences has the maximum PAPR reduction performance. The number of near optimal iteration is derived to prevent exhausted iterations. It is also shown that there is no bit error rate (BER) degradation with the proposed technique in LTE downlink system. PMID:24883376

Patient-Centered Appointment Scheduling Using Agent-Based Simulation

PubMed Central

Turkcan, Ayten; Toscos, Tammy; Doebbeling, Brad N.

2014-01-01

Enhanced access and continuity are key components of patient-centered care. Existing studies show that several interventions such as providing same day appointments, walk-in services, after-hours care, and group appointments, have been used to redesign the healthcare systems for improved access to primary care. However, an intervention focusing on a single component of care delivery (i.e. improving access to acute care) might have a negative impact other components of the system (i.e. reduced continuity of care for chronic patients). Therefore, primary care clinics should consider implementing multiple interventions tailored for their patient population needs. We collected rapid ethnography and observations to better understand clinic workflow and key constraints. We then developed an agent-based simulation model that includes all access modalities (appointments, walk-ins, and after-hours access), incorporate resources and key constraints and determine the best appointment scheduling method that improves access and continuity of care. This paper demonstrates the value of simulation models to test a variety of alternative strategies to improve access to care through scheduling. PMID:25954423

Connecting AAC devices to the world of information technology.

PubMed

Caves, Kevin; Shane, Howard C; DeRuyter, Frank

2002-01-01

Modern day information technology (IT) is converging around wireless networks. It is now possible to check E-mail and view information from the World Wide Web from commercially available mobile phones. For individuals with disabilities, the ability to access multiple and different types of information not only promises convenience, but also can help to promote independence and facilitate access to public and private information systems. There are many barriers to access for people with disabilities, including technological hurdles, security, privacy, and access to these emerging wireless technologies. However, legislation, advocacy, standards, and research and development can ensure that users of augmentative and alternative communication (AAC) and assistive technology have access to these technologies. This article provides a historical context for the field of AAC and IT development, a review of the current state of these technologies, a glimpse of the potential of wireless information access for the lives of AAC users, and a description of some of the barriers and enablers to making access available to users of AAC and assistive technologies.

'It's risky to walk in the city with syringes': understanding access to HIV/AIDS services for injecting drug users in the former Soviet Union countries of Ukraine and Kyrgyzstan

PubMed Central

2011-01-01

Background Despite massive scale up of funds from global health initiatives including the Global Fund to Fight AIDS, Tuberculosis and Malaria (Global Fund) and other donors, the ambitious target agreed by G8 leaders in 2005 in Gleneagles to achieve universal access to HIV/AIDS treatment by 2010 has not been reached. Significant barriers to access remain in former Soviet Union (FSU) countries, a region now recognised as a priority area by policymakers. There have been few empirical studies of access to HIV/AIDS services in FSU countries, resulting in limited understanding and implementation of accessible HIV/AIDS interventions. This paper explores the multiple access barriers to HIV/AIDS services experienced by a key risk group-injecting drug users (IDUs). Methods Semi-structured interviews were conducted in two FSU countries-Ukraine and Kyrgyzstan-with clients receiving Global Fund-supported services (Ukraine n = 118, Kyrgyzstan n = 84), service providers (Ukraine n = 138, Kyrgyzstan n = 58) and a purposive sample of national and subnational stakeholders (Ukraine n = 135, Kyrgyzstan n = 86). Systematic thematic analysis of these qualitative data was conducted by country teams, and a comparative synthesis of findings undertaken by the authors. Results Stigmatisation of HIV/AIDS and drug use was an important barrier to IDUs accessing HIV/AIDS services in both countries. Other connected barriers included: criminalisation of drug use; discriminatory practices among government service providers; limited knowledge of HIV/AIDS, services and entitlements; shortages of commodities and human resources; and organisational, economic and geographical barriers. Conclusions Approaches to thinking about universal access frequently assume increased availability of services means increased accessibility of services. Our study demonstrates that while there is greater availability of HIV/AIDS services in Ukraine and Kyrgyzstan, this does not equate with greater accessibility because of multiple, complex, and interrelated barriers to HIV/AIDS service utilisation at the service delivery level. Factors external to, as well as within, the health sector are key to understanding the access deficit in the FSU where low or concentrated HIV/AIDS epidemics are prevalent. Funders of HIV/AIDS programmes need to consider how best to tackle key structural and systemic drivers of access including prohibitionist legislation on drugs use, limited transparency and low staff salaries within the health sector. PMID:21752236

Space Network IP Services (SNIS): An Architecture for Supporting Low Earth Orbiting IP Satellite Missions

NASA Technical Reports Server (NTRS)

Israel, David J.

2005-01-01

The NASA Space Network (SN) supports a variety of missions using the Tracking and Data Relay Satellite System (TDRSS), which includes ground stations in White Sands, New Mexico and Guam. A Space Network IP Services (SNIS) architecture is being developed to support future users with requirements for end-to-end Internet Protocol (IP) communications. This architecture will support all IP protocols, including Mobile IP, over TDRSS Single Access, Multiple Access, and Demand Access Radio Frequency (RF) links. This paper will describe this architecture and how it can enable Low Earth Orbiting IP satellite missions.

Demonstration of an SOA-assisted open metro-access infrastructure for heterogeneous services.

PubMed

Schmuck, H; Bonk, R; Poehlmann, W; Haslach, C; Kuebart, W; Karnick, D; Meyer, J; Fritzsche, D; Weis, E; Becker, J; Freude, W; Pfeiffer, T

2014-01-13

An open converged metro-access network approach allows for sharing optical layer resources like fibers and optical spectrum among different services and operators. We demonstrated experimentally the feasibility of such a concept by the simultaneous operation of multiple services showing different modulation formats and multiplexing techniques. Flexible access nodes are implemented including semiconductor optical amplifiers to create a transparent and reconfigurable optical ring network. The impact of cascaded optical amplifiers on the signal quality is studied along the ring. In addition, the influence of high power rival signals in the same waveband and in the same fiber is analyzed.

On the Performance Evaluation of a MIMO–WCDMA Transmission Architecture for Building Management Systems

PubMed Central

Tsampasis, Eleftherios; Gkonis, Panagiotis K.; Trakadas, Panagiotis; Zahariadis, Theodοre

2018-01-01

The goal of this study was to investigate the performance of a realistic wireless sensor nodes deployment in order to support modern building management systems (BMSs). A three-floor building orientation is taken into account, where each node is equipped with a multi-antenna system while a central base station (BS) collects and processes all received information. The BS is also equipped with multiple antennas; hence, a multiple input–multiple output (MIMO) system is formulated. Due to the multiple reflections during transmission in the inner of the building, a wideband code division multiple access (WCDMA) physical layer protocol has been considered, which has already been adopted for third-generation (3G) mobile networks. Results are presented for various MIMO orientations, where the mean transmission power per node is considered as an output metric for a specific signal-to-noise ratio (SNR) requirement and number of resolvable multipath components. In the first set of presented results, the effects of multiple access interference on overall transmission power are highlighted. As the number of mobile nodes per floor or the requested transmission rate increases, MIMO systems of a higher order should be deployed in order to maintain transmission power at adequate levels. In the second set of results, a comparison is performed among transmission in diversity combining and spatial multiplexing mode, which clearly indicate that the first case is the most appropriate solution for indoor communications. PMID:29316720

Innovative Approaches Address Aging and Mental Health Needs in LGBTQ Communities

PubMed Central

Hoy-Ellis, Charles P.; Ator, Michael; Kerr, Christopher; Milford, Jessica

2016-01-01

LGBTQ older adults have higher levels of psychological distress as compared to older adults in general. They also experience multiple barriers to accessing equitable, culturally competent mental health and aging services because of their distinct histories and particular social contexts. This article discusses this lack of access to services, and highlights an innovative way mental health services are being delivered in LGBTQ communities. PMID:28366982

Survey of Federal, National, and International standards applicable to the NASA applications data services

NASA Technical Reports Server (NTRS)

Kuch, T.; Sakamoto, R.

1981-01-01

An applications data service (ADS) was developed to meet the challenges in the data access and integration. The ADS provides a common service to locate and access applications data electronically and integrate the cross correlative data sets required by multiple users. Its catalog and network services increase data visibility as well as provide the data in a more rapid manner and a usable form.

Establishing Core Mental Health Workforce Attributes for the Effective Mental Health Care of People with an Intellectual Disability and Co-Occurring Mental Ill Health

ERIC Educational Resources Information Center

Weise, Janelle; Fisher, Karen R.; Trollor, Julian N.

2017-01-01

Background: People with intellectual disability experience high rates of mental ill health but multiple barriers to access to quality mental health care. One significant barrier to access is a generalist mental health workforce that lacks capacity, and consensus on what constitutes core workforce competencies in this area. As such, the first step…

The patient's perspective: How to create awareness for improving access to care and treatment of MS patients?

PubMed

Vermersch, Patrick; Faller, Andreas; Czarnota-Szałkowska, Dominika; Meesen, Bianca; Thalheim, Christoph

2016-08-01

There is currently no known cure for multiple sclerosis (MS). Four stakeholders play a major role in MS: healthcare professionals, regulators, payers and patients. In Europe, patients are represented by the European Multiple Sclerosis Platform (EMSP), which aims to improve MS management and patients' quality of life. The EMSP has recently shown that there are major disparities in Europe in terms of access to care and treatment. Implementing the Code of Good Practice and a standardised MS nurse training may be useful in harmonising MS management across Europe. Additionally, the burden for novel therapeutic options to be approved by regulatory agencies has to decrease in order to provide faster access of treatment to patients. Data collection (e.g. national registers) also appears crucial to help research and shape the most effective policy in each country. Finally, people with MS should get appropriate (financial) support in order to complete their studies and find a job, as their active participation in society requires proper access to education and employment. Moreover, as they are the ones affected by MS, they seem to be best placed to represent themselves and their needs and should be consulted more often during decision-making processes by policy makers, regulators and payers. © The Author(s), 2016.

The virtual library: Coming of age

NASA Technical Reports Server (NTRS)

Hunter, Judy F.; Cotter, Gladys A.

1994-01-01

With the high speed networking capabilities, multiple media options, and massive amounts of information that exist in electronic format today, the concept of a 'virtual' library or 'library without walls' is becoming viable. In virtual library environment, the information processed goes beyond the traditional definition of documents to include the results of scientific and technical research and development (reports, software, data) recorded in any format or media: electronic, audio, video, or scanned images. Network access to information must include tools to help locate information sources and navigate the networks to connect to the sources, as well as methods to extract the relevant information. Graphical User Interfaces (GUI's) that are intuitive and navigational tools such as Intelligent Gateway Processors (IGP) will provide users with seamless and transparent use of high speed networks to access, organize, and manage information. Traditional libraries will become points of electronic access to information on multiple medias. The emphasis will be towards unique collections of information at each library rather than entire collections at every library. It is no longer a question of whether there is enough information available; it is more a question of how to manage the vast volumes of information. The future equation will involve being able to organize knowledge, manage information, and provide access at the point of origin.

An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things.

PubMed

Yi, Meng; Chen, Qingkui; Xiong, Neal N

2016-11-03

This paper considers the distributed access and control problem of massive wireless sensor networks' data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate.

Routes to DNA accessibility: alternative pathways for nucleosome unwinding.

PubMed

Schlingman, Daniel J; Mack, Andrew H; Kamenetska, Masha; Mochrie, Simon G J; Regan, Lynne

2014-07-15

The dynamic packaging of DNA into chromatin is a key determinant of eukaryotic gene regulation and epigenetic inheritance. Nucleosomes are the basic unit of chromatin, and therefore the accessible states of the nucleosome must be the starting point for mechanistic models regarding these essential processes. Although the existence of different unwound nucleosome states has been hypothesized, there have been few studies of these states. The consequences of multiple states are far reaching. These states will behave differently in all aspects, including their interactions with chromatin remodelers, histone variant exchange, and kinetic properties. Here, we demonstrate the existence of two distinct states of the unwound nucleosome, which are accessible at physiological forces and ionic strengths. Using optical tweezers, we measure the rates of unwinding and rewinding for these two states and show that the rewinding rates from each state are different. In addition, we show that the probability of unwinding into each state is dependent on the applied force and ionic strength. Our results demonstrate not only that multiple unwound states exist but that their accessibility can be differentially perturbed, suggesting possible roles for these states in gene regulation. For example, different histone variants or modifications may facilitate or suppress access to DNA by promoting unwinding into one state or the other. We anticipate that the two unwound states reported here will be the basis for future models of eukaryotic transcriptional control. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Optical multidimensional multiple access(O-MDMA): a new concept for free-space laser communication based on photonic mixer devices

NASA Astrophysics Data System (ADS)

Hess, Holger; Albrecht, Martin; Grothof, Markus; Hussmann, Stephan; Schwarte, Rudolf

2004-01-01

Working on optical distance measurement a new optical correlator was developed at the Institute for Data Processing of the University of Siegen in the last years. The so called Photonic Mixer Device (PMD), to be meant originally for laser ranging systems, offers a lot of advantages for wireless optical data communication like high speed spatial light demodulation up to the GHz range and inherent backlight suppression. This contribution describes the application of such PMDs in a free space interconnect based on the principle of Multi Dimensional Multiple Access (MDMA) and the advantages of this new approach, starting from the MDMA principle and followed by the fundamental functionality of PMDs. After that an Optical MDMA (O-MDMA) demonstrator and first measurement results will be presented.

Comparison of a video-based assessment and a multiple stimulus assessment to identify preferred jobs for individuals with significant intellectual disabilities.

PubMed

Horrocks, Erin L; Morgan, Robert L

2009-01-01

The authors compare two methods of identifying job preferences for individuals with significant intellectual disabilities. Three individuals with intellectual disabilities between the ages of 19 and 21 participated in a video-based preference assessment and a multiple stimulus without replacement (MSWO) assessment. Stimulus preference assessment procedures typically involve giving participants access to the selected stimuli to increase the probability that participants will associate the selected choice with the actual stimuli. Although individuals did not have access to the selected stimuli in the video-based assessment, results indicated that both assessments identified the same highest preference job for all participants. Results are discussed in terms of using a video-based assessment to accurately identify job preferences for individuals with developmental disabilities.

A performance analysis of DS-CDMA and SCPC VSAT networks

NASA Technical Reports Server (NTRS)

Hayes, David P.; Ha, Tri T.

1990-01-01

Spread-spectrum and single-channel-per-carrier (SCPC) transmission techniques work well in very small aperture terminal (VSAT) networks for multiple-access purposes while allowing the earth station antennas to remain small. Direct-sequence code-division multiple-access (DS-CDMA) is the simplest spread-spectrum technique to use in a VSAT network since a frequency synthesizer is not required for each terminal. An examination is made of the DS-CDMA and SCPC Ku-band VSAT satellite systems for low-density (64-kb/s or less) communications. A method for improving the standardf link analysis of DS-CDMA satellite-switched networks by including certain losses is developed. The performance of 50-channel full mesh and star network architectures is analyzed. The selection of operating conditions producing optimum performance is demonstrated.

Fast converging minimum probability of error neural network receivers for DS-CDMA communications.

PubMed

Matyjas, John D; Psaromiligkos, Ioannis N; Batalama, Stella N; Medley, Michael J

2004-03-01

We consider a multilayer perceptron neural network (NN) receiver architecture for the recovery of the information bits of a direct-sequence code-division-multiple-access (DS-CDMA) user. We develop a fast converging adaptive training algorithm that minimizes the bit-error rate (BER) at the output of the receiver. The adaptive algorithm has three key features: i) it incorporates the BER, i.e., the ultimate performance evaluation measure, directly into the learning process, ii) it utilizes constraints that are derived from the properties of the optimum single-user decision boundary for additive white Gaussian noise (AWGN) multiple-access channels, and iii) it embeds importance sampling (IS) principles directly into the receiver optimization process. Simulation studies illustrate the BER performance of the proposed scheme.

A CDMA system implementation with dimming control for visible light communication

NASA Astrophysics Data System (ADS)

Chen, Danyang; Wang, Jianping; Jin, Jianli; Lu, Huimin; Feng, Lifang

2018-04-01

Visible light communication (VLC), using solid-state lightings to transmit information, has become a complement technology to wireless radio communication. As a realistic multiple access scheme for VLC system, code division multiple access (CDMA) has attracted more and more attentions in recent years. In this paper, we address and implement an improved CDMA scheme for VLC system. The simulation results reveal that the improved CDMA scheme not only supports multi-users' transmission but also maintains dimming value at about 50% and enhances the system efficiency. It can also realize the flexible dimming control by adjusting some parameters of system structure, which rarely affects the system BER performance. A real-time experimental VLC system with improved CDMA scheme is performed based on field programmable gate array (FPGA), reaching a good BER performance.

LiFi: transforming fibre into wireless

NASA Astrophysics Data System (ADS)

Yin, Liang; Islim, Mohamed Sufyan; Haas, Harald

2017-01-01

Light-fidelity (LiFi) uses energy-efficient light-emitting diodes (LEDs) for high-speed wireless communication, and it has a great potential to be integrated with fibre communication for future gigabit networks. However, by making fibre communication wireless, multiuser interference arises. Traditional methods use orthogonal multiple access (OMA) for interference avoidance. In this paper, multiuser interference is exploited with the use of non-orthogonal multiple access (NOMA) relying on successive interference cancellation (SIC). The residual interference due to imperfect SIC in practical scenarios is characterized with a proportional model. Results show that NOMA offers 5 -10 dB gain on the equivalent signal-to-interference-plus-noise ratio (SINR) over OMA. The bit error rate (BER) performance of direct current optical orthogonal frequency division multiplexing (DCO-OFDM) is shown to be significantly improved when SIC is used.

Code-division multiple-access multiuser demodulator by using quantum fluctuations.

PubMed

Otsubo, Yosuke; Inoue, Jun-Ichi; Nagata, Kenji; Okada, Masato

2014-07-01

We examine the average-case performance of a code-division multiple-access (CDMA) multiuser demodulator in which quantum fluctuations are utilized to demodulate the original message within the context of Bayesian inference. The quantum fluctuations are built into the system as a transverse field in the infinite-range Ising spin glass model. We evaluate the performance measurements by using statistical mechanics. We confirm that the CDMA multiuser modulator using quantum fluctuations achieve roughly the same performance as the conventional CDMA multiuser modulator through thermal fluctuations on average. We also find that the relationship between the quality of the original information retrieval and the amplitude of the transverse field is somehow a "universal feature" in typical probabilistic information processing, viz., in image restoration, error-correcting codes, and CDMA multiuser demodulation.

Code-division multiple-access multiuser demodulator by using quantum fluctuations

NASA Astrophysics Data System (ADS)

Otsubo, Yosuke; Inoue, Jun-ichi; Nagata, Kenji; Okada, Masato

2014-07-01

We examine the average-case performance of a code-division multiple-access (CDMA) multiuser demodulator in which quantum fluctuations are utilized to demodulate the original message within the context of Bayesian inference. The quantum fluctuations are built into the system as a transverse field in the infinite-range Ising spin glass model. We evaluate the performance measurements by using statistical mechanics. We confirm that the CDMA multiuser modulator using quantum fluctuations achieve roughly the same performance as the conventional CDMA multiuser modulator through thermal fluctuations on average. We also find that the relationship between the quality of the original information retrieval and the amplitude of the transverse field is somehow a "universal feature" in typical probabilistic information processing, viz., in image restoration, error-correcting codes, and CDMA multiuser demodulation.

The Relationship between Iranian EFL High School Students' Multiple Intelligence Scores and Their Use of Learning Strategies

ERIC Educational Resources Information Center

Hajhashemi, Karim; Ghombavani, Fatemeh Parasteh; Amirkhiz, Seyed Yasin Yazdi

2011-01-01

According to the theory of multiple intelligences (MI) propounded by Gardner (1983, 1999a, 1999b), each individual has a multitude of intelligences that are quite independent of each other and each individual has a unique cognitive profile. Having access to the MI profiles and learning strategies of learners could help the teachers in planning…

Multiple-User, Multitasking, Virtual-Memory Computer System

NASA Technical Reports Server (NTRS)

Generazio, Edward R.; Roth, Don J.; Stang, David B.

1993-01-01

Computer system designed and programmed to serve multiple users in research laboratory. Provides for computer control and monitoring of laboratory instruments, acquisition and anlaysis of data from those instruments, and interaction with users via remote terminals. System provides fast access to shared central processing units and associated large (from megabytes to gigabytes) memories. Underlying concept of system also applicable to monitoring and control of industrial processes.

Managing Teacher Leave and Absence in South African Rural Schools: Implications for Supporting Schools in Contexts of Multiple-Deprivation

ERIC Educational Resources Information Center

Moletsane, Relebohile; Juan, Andrea; Prinsloo, Cas; Reddy, Vijay

2015-01-01

Research increasingly points to the negative impacts of teacher absence from school on access to schooling and success in learning in schools, in particular in schools in areas of multiple-deprivation (including rural schools). South African schools are no exception. In this regard, like any other employer, the South African Department of Basic…

Career Academies: A Holistic Multiple-Case Study of the Development and Sustainability of High School-College Partnerships in Nebraska

ERIC Educational Resources Information Center

Christensen, Kelly Scott

2014-01-01

The purpose of this qualitative study was to conduct a holistic, multiple-case analysis of career academy partnerships in Nebraska public high schools. Career academies are poised to be an important solution to improving student access to career and technical education in Nebraska while ultimately helping to close the skills gap. This is at a time…

An open source web interface for linking models to infrastructure system databases

NASA Astrophysics Data System (ADS)

Knox, S.; Mohamed, K.; Harou, J. J.; Rheinheimer, D. E.; Medellin-Azuara, J.; Meier, P.; Tilmant, A.; Rosenberg, D. E.

2016-12-01

Models of networked engineered resource systems such as water or energy systems are often built collaboratively with developers from different domains working at different locations. These models can be linked to large scale real world databases, and they are constantly being improved and extended. As the development and application of these models becomes more sophisticated, and the computing power required for simulations and/or optimisations increases, so has the need for online services and tools which enable the efficient development and deployment of these models. Hydra Platform is an open source, web-based data management system, which allows modellers of network-based models to remotely store network topology and associated data in a generalised manner, allowing it to serve multiple disciplines. Hydra Platform uses a web API using JSON to allow external programs (referred to as `Apps') to interact with its stored networks and perform actions such as importing data, running models, or exporting the networks to different formats. Hydra Platform supports multiple users accessing the same network and has a suite of functions for managing users and data. We present ongoing development in Hydra Platform, the Hydra Web User Interface, through which users can collaboratively manage network data and models in a web browser. The web interface allows multiple users to graphically access, edit and share their networks, run apps and view results. Through apps, which are located on the server, the web interface can give users access to external data sources and models without the need to install or configure any software. This also ensures model results can be reproduced by removing platform or version dependence. Managing data and deploying models via the web interface provides a way for multiple modellers to collaboratively manage data, deploy and monitor model runs and analyse results.

The relationship between employment and health and health care among working-age adults with and without disabilities in the United States.

PubMed

Reichard, Amanda; Stransky, Michelle; Brucker, Debra; Houtenville, Andrew

2018-05-20

To better understand the relationship between employment and health and health care for people with disabilities in the United States (US). We pooled US Medical Expenditure Panel Survey (2004-2010) data to examine health status, and access to health care among working-age adults, comparing people with physical disabilities or multiple disabilities to people without disabilities, based on their employment status. Logistic regression and least squares regression were conducted, controlling for sociodemographics, health insurance (when not the outcome), multiple chronic conditions, and need for assistance. Employment was inversely related to access to care, insurance, and obesity. Yet, people with disabilities employed in the past year reported better general and mental health than their peers with the same disabilities who were not employed. Those who were employed were more likely to have delayed/forgone necessary care, across disability groups. Part-time employment, especially for people with multiple limitations, was associated with better health and health care outcomes than full-time employment. Findings highlight the importance of addressing employment-related causes of delayed or foregone receipt of necessary care (e.g., flex-time for attending appointments) that exist for all workers, especially those with physical or multiple disabilities. Implications for rehabilitation These findings demonstrate that rehabilitation professionals who are seeking to support employment for persons with physical limitations need to ensure that overall health concerns are adequately addressed, both for those seeking employment and for those who are currently employed. Assisting clients in prioritizing health equally with employment can ensure that both areas receive sufficient attention. Engaging with employers to develop innovative practices to improve health, health behaviors and access to care for employees with disabilities can decrease turnover, increase productivity, and ensure longer job tenure.

BioSYNTHESIS: access to a knowledge network of health sciences databases.

PubMed

Broering, N C; Hylton, J S; Guttmann, R; Eskridge, D

1991-04-01

Users of the IAIMS Knowledge Network at the Georgetown University Medical Center have access to multiple in-house and external databases from a single point of entry through BioSYNTHESIS. The IAIMS project has developed a rich environment of biomedical information resources that represent a medical decision support system for campus physicians and students. The BioSYNTHESIS system is an information navigator that provides transparent access to a Knowledge Network of over a dozen databases. These multiple health sciences databases consist of bibliographic, informational, diagnostic, and research systems which reside on diverse computers such as DEC VAXs, SUN 490, AT&T 3B2s, Macintoshes, IBM PC/PS2s and the AT&T ISN and SYTEK network systems. Ethernet and TCP/IP protocols are used in the network architecture. BioSYNTHESIS also provides network links to the other campus libraries and to external institutions. As additional knowledge resources and technological advances have become available. BioSYNTHESIS has evolved from a two phase to a three phase program. Major components of the system including recent achievements and future plans are described.

Central venous access in children: indications, devices, and risks.

PubMed

Ares, Guillermo; Hunter, Catherine J

2017-06-01

Central venous catheters (CVCs) have a prominent role in the diagnostic and therapy of neonates and children. Herein, we describe the multiple indications for CVC use and the different devices available for central venous access. Given the prevalent use of CVCs, healthcare systems are focused on reducing complications from their use, particularly central line-associated bloodstream infections (CLABSIs). The most up-to-date information available sheds light on best practices and future areas of investigation. Large systematic reviews of randomized trials suggest that ultrasound guidance for placement of CVCs in children is safer than using blind technique, at least for internal jugular vein access. Appropriate catheter tip placement is associated with decreased complications. Furthermore, the prophylactic use of ethanol lock between cycles of parenteral nutrition administration has reduced the rates of CLABSI. A recent randomized trial in pediatric CVCs showed a benefit with antibiotic-coated CVCs. Based on the available evidence, multiple techniques for CVC placement are still valid, including the landmark technique based on practitioner experience, but ultrasound guidance has been shown to decrease complications from line placement. Adherence to CVC care protocols is essential in reducing infectious complications.

A System for Distributing Real-Time Customized (NEXRAD-Radar) Geosciences Data

NASA Astrophysics Data System (ADS)

Singh, Satpreet; McWhirter, Jeff; Krajewski, Witold; Kruger, Anton; Goska, Radoslaw; Seo, Bongchul; Domaszczynski, Piotr; Weber, Jeff

2010-05-01

Hydrometeorologists and hydrologists can benefit from (weather) radar derived rain products, including rain rates and accumulations. The Hydro-NEXRAD system (HNX1) has been in operation since 2006 at IIHR-Hydroscience and Engineering at The University of Iowa. It provides rapid and user-friendly access to such user-customized products, generated using archived Weather Surveillance Doppler Radar (WSR-88D) data from the NEXRAD weather radar network in the United States. HNX1 allows researchers to deal directly with radar-derived rain products, without the burden of the details of radar data collection, quality control, processing, and format conversion. A number of hydrologic applications can benefit from a continuous real-time feed of customized radar-derived rain products. We are currently developing such a system, Hydro-NEXRAD 2 (HNX2). HNX2 collects real-time, unprocessed data from multiple NEXRAD radars as they become available, processes them through a user-configurable pipeline of data-processing modules, and then publishes processed products at regular intervals. Modules in the data processing pipeline encapsulate algorithms such as non-meteorological echo detection, range correction, radar-reflectivity-rain rate (Z-R) conversion, advection correction, merging products from multiple radars, and grid transformations. HNX2's implementation presents significant challenges, including quality-control, error-handling, time-synchronization of data from multiple asynchronous sources, generation of multiple-radar metadata products, distribution of products to a user base with diverse needs and constraints, and scalability. For content management and distribution, HNX2 uses RAMADDA (Repository for Archiving, Managing and Accessing Diverse Data), developed by the UCAR/Unidata Program Center in the Unites States. RAMADDA allows HNX2 to publish products through automation and gives users multiple access methods to the published products, including simple web-browser based access, and OpenDAP access. The latter allows a user to set up automation at his/her end, and fetch new data from HNX2 at regular intervals. HNX2 uses a two-dimensional metadata structure called a mosaic for managing metadata of the rain products. Currently, HNX2 is in pre-production state and is serving near real-time rain-rate map data-products for individual radars and merged data-products from seven radars covering the state of Iowa in the United States. These products then drive a rainfall-runoff model called CUENCAS, which is used as part of the Iowa Flood Center (housed at The University of Iowa) real-time flood forecasting system. We are currently developing a generalized scalable framework that will run on inexpensive hardware and will provide products for basins anywhere in the continental United States.

Health care access and support for disabled women in Canada: falling short of the UN Convention on the Rights of Persons with Disabilities: a qualitative study.

PubMed

Gibson, Barbara E; Mykitiuk, Roxanne

2012-01-01

The United Nations Convention on the Rights of Persons with Disabilities and other international human rights conventions guarantee the fundamental human rights to physical, social, and psychological health. The purpose of this study was to examine whether these rights are being upheld in Canada for disabled women. An interpretive, qualitative, focus group design was employed. Participants were women 18 to 67 years of age with a self-identified physical, sensory, cognitive, and/or psychiatric impairment. Eleven focus groups were conducted with 74 disabled women from urban and rural settings in Northern Ontario, Manitoba, and Nova Scotia. The data were analyzed for themes using a flexible coding system derived from and consistent with the research objectives and the study's human rights framework. Participants described multiple intersecting factors that impeded or facilitated access to health care. Services included both generic health services and impairment-specific services. Participants experienced a number of barriers accessing professionals, support programs, and services. These are described under three broad themes: 1) Labyrinthine health service 'systems,' 2) assumptions, attitudes, and discriminatory practices, and 3) inadequate sexual health or reproductive services and supports. The results suggest that Canada falls significantly short of guaranteeing disabled women's human rights to access health care supports and services. Access barriers resulted from the inefficiencies and complexities of the multiple agencies and programs that disabled women had to navigate, difficulties accessing information on available services, and negative attitudes of some health and social service providers. Copyright © 2012 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Access to parks and physical activity: an eight country comparison.

PubMed

Schipperijn, Jasper; Cerin, Ester; Adams, Marc A; Reis, Rodrigo; Smith, Graham; Cain, Kelli; Christiansen, Lars B; van Dyck, Delfien; Gidlow, Christopher; Frank, Lawrence D; Mitáš, Josef; Pratt, Michael; Salvo, Deborah; Schofield, Grant; Sallis, James F

2017-10-01

Several systematic reviews have reported mixed associations between access to parks and physical activity, and suggest that this is due to inconsistencies in the study methods or differences across countries. An international study using consistent methods is needed to investigate the association between access to parks and physical activity. The International Physical Activity and Environment Network (IPEN) Adult Study is a multi-country cross-sectional study using a common design and consistent methods. Accelerometer, survey and Geographic Information Systems (GIS) data for 6,181 participants from 12 cities in 8 countries (Belgium, Brazil, Czech Republic, Denmark, Mexico, New Zealand, UK, USA) were used to estimate the strength and shape of associations of 11 measures of park access (1 perceived and 10 GIS-based measures) with accelerometer-based moderate-to-vigorous physical activity (MVPA) and four types of self-reported leisure-time physical activity. Associations were estimated using generalized additive mixed models. More parks within 1 km from participants' homes were associated with greater leisure-time physical activity and accelerometer-measured MVPA. Respondents who lived in the neighborhoods with the most parks did on average 24 minutes more MVPA per week than those living in the neighborhoods with the lowest number of parks. Perceived proximity to a park was positively associated with multiple leisure-time physical activity outcomes. Associations were homogeneous across all cities studied. Living in neighborhoods with many parks could contribute with up to 1/6 of the recommended weekly Having multiple parks nearby was the strongest positive correlate of PA. To increase comparability and validity of park access measures, we recommend that researchers, planners and policy makers use the number of parks within 1 km travel distance of homes as an objective indicator for park access in relation to physical activity.

Simultaneous Iliac Vein Bovine Pericardial Patch Venoplasty and Creation of PTFE Lower Limb Arteriovenous Fistula Graft for Rescue Vascular Access.

PubMed

Meecham, Lewis; Fisher, Owain; Kirby, George; Evans, Richard; Buxton, Pauline; Legge, Jocelyn; Rajagopalan, Sriram; Asquith, John; Pherwani, Arun

2016-10-01

We present a case of external iliac vein patch venoplasty to accommodate rescue vascular access via a polytetrafluoroethylene loop arteriovenous fistula graft (AVG) for a patient with multiple central venous stenoses. A 35-year-old female with anti-glomerular basement membrane antibody disease required rescue vascular access for hemodialysis. Repeated occlusion and/or thrombosis of long-term central venous access cannulae, to facilitate dialysis, had caused stenosis of brachiocephalic veins: right external iliac vein and occlusion of the left common iliac vein. A previous right brachiobasilic fistula had occluded within 1 year. No other upper limb options for arteriovenous fistula (AVF) were available. A right external iliac vein bovine patch angioplasty concurrently with a polytetrafluoroethylene AV graft between common femoral artery and common femoral vein was performed to restore venous patency and allow rescue dialysis access. At 3-year follow-up, the fistula remains widely patent with 2 L/min flow rates and no recurrent stenosis to the treated iliac vein. She has not required any further surgical or interventional radiological procedures to maintain fistula or central venous patency. Central venous stenosis or occlusion is common for patients requiring dialysis, especially those with multiple previous long-term central venous cannulations. If restriction of outflow is present, AVF may fail. Venous patch angioplasty in these cases is a successful technique, allowing AVF formation and long-term patency. Central venous stenosis can be treated successfully with patch venoplasty to accommodate AVF/AVG formation for rescue vascular access; this is a potentially lifesaving intervention for patients requiring dialysis. Copyright © 2016 Elsevier Inc. All rights reserved.

Action research to improve methods of delivery and feedback in an Access Grid Room environment

NASA Astrophysics Data System (ADS)

McArthur, Lynne C.; Klass, Lara; Eberhard, Andrew; Stacey, Andrew

2011-12-01

This article describes a qualitative study which was undertaken to improve the delivery methods and feedback opportunity in honours mathematics lectures which are delivered through Access Grid Rooms. Access Grid Rooms are facilities that provide two-way video and audio interactivity across multiple sites, with the inclusion of smart boards. The principal aim was to improve the student learning experience, given the new environment. The specific aspects of the course delivery that the study focused on included presentation of materials and provision of opportunities for interaction between the students and between students and lecturers. The practical considerations in the delivery of distance learning are well documented in the literature, and similar problems arise in the Access Grid Room environment; in particular, those of limited access to face-to-face interaction and the reduction in peer support. The nature of the Access Grid Room classes implies that students studying the same course can be physically situated in different cities, and possibly in different countries. When studying, it is important that students have opportunity to discuss new concepts with others; particularly their peers and their lecturer. The Access Grid Room environment also presents new challenges for the lecturer, who must learn new skills in the delivery of materials. The unique nature of Access Grid Room technology offers unprecedented opportunity for effective course delivery and positive outcomes for students, and was developed in response to a need to be able to interact with complex data, other students and the instructor, in real-time, at a distance and from multiple sites. This is a relatively new technology and as yet there has been little or no studies specifically addressing the use and misuse of the technology. The study found that the correct placement of cameras and the use of printed material and smart boards were all crucial to the student experience. In addition, the inclusion of special tutorial type sessions were necessary to provide opportunities to students for one-on-one discussion with both lecturer and other students. This study contributes to the broader understanding of distance education in general and future Access Grid Room course delivery in particular.

The Correlation Between Poverty and Access to Essential Surgical Care in Ghana: A Geospatial Analysis

PubMed Central

Stewart, Barclay T.; Gyedu, Adam; Boakye, Godfred; Lewis, Daniel; Hoogerboord, Marius; Mock, Charles

2017-01-01

Background Surgical disease burden falls disproportionately on individuals in low- and middle-income countries. These populations are also the least likely to have access to surgical care. Understanding the barriers to access in these populations is therefore necessary to meet the global surgical need. Methods Using geospatial methods, this study explores the district-level variation of two access barriers in Ghana: poverty and spatial access to care. National survey data were used to estimate the average total household expenditure (THE) in each district. Estimates of the spatial access to essential surgical care were generated from a cost-distance model based on a recent surgical capacity assessment. Correlations were analyzed using regression and displayed cartographically. Results Both THE and spatial access to surgical care were found to have statistically significant regional variation in Ghana (p < 0.001). An inverse relationship was identified between THE and spatial access to essential surgical care (β −5.15 USD, p < 0.001). Poverty and poor spatial access to surgical care were found to co-localize in the northwest of the country. Conclusions Multiple barriers to accessing surgical care can coexist within populations. A careful understanding of all access barriers is necessary to identify and target strategies to address unmet surgical need within a given population. PMID:27766400

Upper extremity access for fenestrated endovascular aortic aneurysm repair is not associated with increased morbidity.

PubMed

Knowles, Martyn; Nation, David A; Timaran, David E; Gomez, Luis F; Baig, M Shadman; Valentine, R James; Timaran, Carlos H

2015-01-01

Fenestrated endovascular aortic aneurysm repair (FEVAR) is an alternative to open repair in patients with complex abdominal aortic aneurysms who are neither fit nor suitable for standard open or endovascular repair. Chimney and snorkel grafts are other endovascular alternatives but frequently require bilateral upper extremity access that has been associated with a 3% to 10% risk of stroke. However, upper extremity access is also frequently required for FEVAR because of the caudal orientation of the visceral vessels. The purpose of this study was to assess the use of upper extremity access for FEVAR and the associated morbidity. During a 5-year period, 148 patients underwent FEVAR, and upper extremity access for FEVAR was used in 98 (66%). Outcomes were compared between those who underwent upper extremity access and those who underwent femoral access alone. The primary end point was a cerebrovascular accident or transient ischemic attack, and the secondary end point was local access site complications. The mean number of fenestrated vessels was 3.07 ± 0.81 (median, 3) for a total of 457 vessels stented. Percutaneous upper extremity access was used in 12 patients (12%) and open access in 86 (88%). All patients who required a sheath size >7F underwent high brachial open access, with the exception of one patient who underwent percutaneous axillary access with a 12F sheath. The mean sheath size was 10.59F ± 2.51F (median, 12F), which was advanced into the descending thoracic aorta, allowing multiple wire and catheter exchanges. One hemorrhagic stroke (one of 98 [1%]) occurred in the upper extremity access group, and one ischemic stroke (one of 54 [2%]) occurred in the femoral-only access group (P = .67). The stroke in the upper extremity access group occurred 5 days after FEVAR and was related to uncontrolled hypertension, whereas the stroke in the femoral group occurred on postoperative day 3. Neither patient had signs or symptoms of a stroke immediately after FEVAR. The right upper extremity was accessed six times without a stroke (0%) compared with the left being accessed 92 times with one stroke (1%; P = .8). Four patients (4%) had local complications related to upper extremity access. One (1%) required exploration for an expanding hematoma after manual compression for a 7F sheath, one (1%) required exploration for hematoma and neurologic symptoms after open access for a 12F sheath, and two patients (2%) with small hematomas did not require intervention. Two (two of 12 [17%]) of these complications were in the percutaneous access group, which were significantly more frequent than in the open group (two of 86 [2%]; P = .02). Upper extremity access appears to be a safe and feasible approach for patients undergoing FEVAR. Open exposure in the upper extremity may be safer than percutaneous access during FEVAR. Unlike chimney and snorkel grafts, upper extremity access during FEVAR is not associated with an increased risk of stroke, despite the need for multiple visceral vessel stenting. Copyright © 2015 Society for Vascular Surgery. All rights reserved.

In the Eye of the Perfect Storm: The Convergence of Policy and Latina/o Trends in Access and Financial Concerns, 1975-2008

ERIC Educational Resources Information Center

Santos, José L.; Sáenz, Victor B.

2014-01-01

The authors paint a national portrait of Latina/o trends over more than 30 years in terms of demographic and financial concerns that pertain to access at 4-year institutions. Using a multiple policy streams framework, the authors contend that growing numbers of Latina/os are in the eye of the perfect storm in a global economy that calls for more…

GenePattern | Informatics Technology for Cancer Research (ITCR)

Cancer.gov

GenePattern is a genomic analysis platform that provides access to hundreds of tools for the analysis and visualization of multiple data types. A web-based interface provides easy access to these tools and allows the creation of multi-step analysis pipelines that enable reproducible in silico research. A new GenePattern Notebook environment allows users to combine GenePattern analyses with text, graphics, and code to create complete reproducible research narratives.

UNificatins and Extensions of the Multiple Access Communications Problem,

DTIC Science & Technology

1981-07-01

Control , Stability and Waiting Time in a Slotted ALOHA Random Access System ," IEEE...quceing, them, the control procedure must tolerate a larger average number of’ messages in the system if it is to limit the number of times that the system ...running fas- ter than real time to provide some flow control for that class . The virtual clocks for every other class merely act as a "gate" which

Gonadal status and physical performance in older men.

PubMed

Maggio, Marcello; Ceda, Gian Paolo; Lauretani, Fulvio; Bandinelli, Stefania; Metter, Earl Jeffrey; Guralnik, Jack M; Basaria, Shehzad; Cattabiani, Chiara; Luci, Michele; Dall'Aglio, Elisabetta; Vignali, Alessandro; Volpi, Riccardo; Valenti, Giorgio; Ferrucci, Luigi

2011-03-01

To test the relationship between gonadal status and objective measures and determinants of physical performance in older men and their determinants. The study included 455 ≥ 65 year older men of InCHIANTI study, Italy, with complete data on testosterone levels, hand grip strength, cross-sectional muscle area (CSMA), short physical performance battery (SPPB). Linear models were used to test the relationship between gonadal status and determinants of physical performance. Three different groups of older men were created: (1) severely hypogonadal (N=23), total testosterone levels ≤ 230 ng /dl; (2) moderately hypogonadal (N=88), total testosterone >230 and < 350 ng/dl) and (3) eugonadal (N=344), testosterone levels ≥ 350 ng/dl. With increased severity of hypogonadal status, participants were significantly older while their BMI was substantially similar. In the age and BMI adjusted analysis, there was a significant difference in haemoglobin levels, hand grip strength and SPPB score (p for trend < 0.001) among three groups, with severely hypogonadal men having lower values of haemoglobin, muscle strength and physical performance. We found no association between testosterone group assignment and calf muscle mass and 4 m walking speed. In the multivariate analysis grip strength (p for trend = 0.004) and haemoglobin (p for trend < 0.0001) but not SPPB and other determinants of physical performance were significantly different between the three groups. In older men, gonadal status is independently associated with some determinants (haemoglobin and muscle strength) of physical performance.

Improving Access to Medicines in Low and Middle Income Countries: Corporate Responsibilities in Context

PubMed Central

Leisinger, Klaus Michael; Garabedian, Laura Faden; Wagner, Anita Katharina

2012-01-01

More than two billion people in low- and middle-income countries (LMIC) lack adequate access to essential medicines. In this paper, we make strong public health, human rights and economic arguments for improving access to medicines in LMIC and discuss the different roles and responsibilities of key stakeholders, including national governments, the international community, and non-governmental organizations (NGOs). We then establish a framework of pharmaceutical firms’ corporate responsibilities - the “must,” the “ought to,” and the “can” dimensions - and make recommendations for actionable business strategies for improving access to medicines. We discuss controversial topics, such as pharmaceutical profits and patents, with the goal of building consensus around facts and working towards a solution. We conclude that partnerships and collaboration among multiple stakeholders are urgently needed to improve equitable access to medicines in LMIC. PMID:23535994

UPC++ Programmer’s Guide (v1.0 2017.9)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachan, J.; Baden, S.; Bonachea, D.

UPC++ is a C++11 library that provides Asynchronous Partitioned Global Address Space (APGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The APGAS model is single program, multiple-data (SPMD), with each separate thread of execution (referred to as a rank, a term borrowed from MPI) having access to local memory as it would in C++. However, APGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the ranks. UPC++ provides numerous methods for accessing and using global memory. In UPC++, allmore » operations that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores.« less

UPC++ Programmer’s Guide, v1.0-2018.3.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachan, J.; Baden, S.; Bonachea, Dan

UPC++ is a C++11 library that provides Partitioned Global Address Space (PGAS) programming. It is designed for writing parallel programs that run efficiently and scale well on distributed-memory parallel computers. The PGAS model is single program, multiple-data (SPMD), with each separate thread of execution (referred to as a rank, a term borrowed from MPI) having access to local memory as it would in C++. However, PGAS also provides access to a global address space, which is allocated in shared segments that are distributed over the ranks. UPC++ provides numerous methods for accessing and using global memory. In UPC++, all operationsmore » that access remote memory are explicit, which encourages programmers to be aware of the cost of communication and data movement. Moreover, all remote-memory access operations are by default asynchronous, to enable programmers to write code that scales well even on hundreds of thousands of cores.« less

DISTRIBUTED AND ACCUMULATED REINFORCEMENT ARRANGEMENTS: EVALUATIONS OF EFFICACY AND PREFERENCE

PubMed Central

DELEON, ISER G.; CHASE, JULIE A.; FRANK-CRAWFORD, MICHELLE A.; CARREAU-WEBSTER, ABBEY B.; TRIGGS, MANDY M.; BULLOCK, CHRISTOPHER E.; JENNETT, HEATHER K.

2015-01-01

We assessed the efficacy of, and preference for, accumulated access to reinforcers, which allows uninterrupted engagement with the reinforcers but imposes an inherent delay required to first complete the task. Experiment 1 compared rates of task completion in 4 individuals who had been diagnosed with intellectual disabilities when reinforcement was distributed (i.e., 30-s access to the reinforcer delivered immediately after each response) and accumulated (i.e., 5-min access to the reinforcer after completion of multiple consecutive responses). Accumulated reinforcement produced response rates that equaled or exceeded rates during distributed reinforcement for 3 participants. Experiment 2 used a concurrent-chains schedule to examine preferences for each arrangement. All participants preferred delayed, accumulated access when the reinforcer was an activity. Three participants also preferred accumulated access to edible reinforcers. The collective results suggest that, despite the inherent delay, accumulated reinforcement is just as effective and is often preferred by learners over distributed reinforcement. PMID:24782203

Random-access algorithms for multiuser computer communication networks. Doctoral thesis, 1 September 1986-31 August 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papantoni-Kazakos, P.; Paterakis, M.

1988-07-01

For many communication applications with time constraints (e.g., transmission of packetized voice messages), a critical performance measure is the percentage of messages transmitted within a given amount of time after their generation at the transmitting station. This report presents a random-access algorithm (RAA) suitable for time-constrained applications. Performance analysis demonstrates that significant message-delay improvement is attained at the expense of minimal traffic loss. Also considered is the case of noisy channels. The noise effect appears at erroneously observed channel feedback. Error sensitivity analysis shows that the proposed random-access algorithm is insensitive to feedback channel errors. Window Random-Access Algorithms (RAAs) aremore » considered next. These algorithms constitute an important subclass of Multiple-Access Algorithms (MAAs); they are distributive, and they attain high throughput and low delays by controlling the number of simultaneously transmitting users.« less

[The global and national context regarding the challenges involved in ensuring adequate access to water for human consumption].

PubMed

Augusto, Lia Giraldo da Silva; Gurgel, Idê Gomes Dantas; Câmara Neto, Henrique Fernandes; de Melo, Carlos Henrique; Costa, André Monteiro

2012-06-01

The scope of this article is to analyze the challenges involved in ensuring access to water for human consumption taking the international and national context into consideration. Based on the UN declaration that access to safe and clean drinking water is a fundamental human right, vulnerabilities are identified that can consist in restrictions to access to adequate supplies. The distribution of water and the population across the planet, pollution, inadequate policies and management lead to environmental injustice. The iniquity of access to water constitutes the contemporary water crisis. From the 1980s onwards, the transnational water market emerged for private control that occurs at three main levels: surface and underground water sources; bottled water; and public water supply services. The conflicts of the multiple uses of water resources, the market and environmental problems have contributed to rendering the health of the population and ecosystems vulnerable. Adequate public policies are essential to ensure the basic human right to access to safe and clean drinking water.

A palliative care hotline for multiple sclerosis: A pilot feasibility study.

PubMed

Knies, Andrea K; Golla, Heidrun; Strupp, Julia; Galushko, Maren; Schipper, Sabine; Voltz, Raymond

2015-08-01

Research findings suggest that patients severely affected by multiple sclerosis benefit from palliative care. Our objectives were to (1) implement a pilot palliative care counseling hotline for severely affected multiple sclerosis patients and their caregivers in order to connect them to palliative care, and (2) evaluate its preliminary feasibility through a pilot study. The hotline was designed in cooperation with the local state association of the German Multiple Sclerosis Society and based on a review of the literature. The initial study setting for the hotline was the broader region of the cities Cologne and Bonn in Germany. The hotline was introduced through a magazine published by the German Multiple Sclerosis Society and leaflets sent to local healthcare providers. Calls were conducted using a semistructured interview guide and documented by a standardized case report form. Measures to assess feasibility were both quantitative (e.g., number of calls) and qualitative (e.g., criteria for eligibility for palliative care). During its pilot year, the hotline received 18 calls. Some 15 callers were included in the analysis, and 10 of these 15 were deemed eligible for palliative care due to such criteria as medical characteristics, care or nursing conditions, caregiver strain, and concerns regarding death and dying. Access to palliative care services could be provided for all 10 callers. Based on our pilot feasibility study, the hotline seems to be a valuable service for patients severely affected by multiple sclerosis (MS) and their caregivers in order to gain information about and access to palliative care. It will be extended on a nationwide scale through a grant of the German Multiple Sclerosis Society. Awareness of the hotline needs to be enhanced in order to attract and support a significant number of new callers.

Advancements in Data Access at the IRIS Data Management Center to Broaden Data Use

NASA Astrophysics Data System (ADS)

Benson, R. B.; Trabant, C. M.; Ahern, T. K.

2013-12-01

The IRIS Data Management Center (DMC) has been serving digital seismic data for more than 20 years and has offered a variety of access mechanisms that have stood the test of time. However, beginning in 2010, and in response to multiple needs being requested from the IRIS DMC, we have developed web service interfaces to access our primary data repository. These new interfaces have rapidly grown in popularity. In 2013, the third full year of their operation, these services were responsible for half of all the data shipped from the DMC. In the same time period, the amount of data shipped from the other data access mechanisms has also increased. This non-linear growth of data shipments reflects the increased data usage by the research community. We believe that our new web service interfaces are well suited to fit future data access needs and signify a significant evolution in integrating different scientific data sets. Based on standardized web technologies, support for writing access software is ubiquitous. As fundamentally programmatic interfaces, the services are well suited for integration into data processing systems, in particular large-scale data processing systems. Their programmatic nature also makes then well suited for use with brokering systems where, for example, data from multiple disciplines can be integrated. In addition to providing access to raw data, the DMC created web services that apply simple, on-the-fly processing and format conversion. Processing the data (e.g. converting to Earth units) and formatting the result into something generally usable (e.g. ASCII) removes important barriers for users working in other disciplines. The end result is that we are shipping a much larger amount of data in a manner more directly usable by users. Many of these principles will be applied to the DMC's future work in the NSF's EarthCube Web Service Building Blocks project.

International Data Sharing in Practice: New Technologies Meet Old Governance.

PubMed

Murtagh, Madeleine J; Turner, Andrew; Minion, Joel T; Fay, Michaela; Burton, Paul R

2016-06-01

The social structures that govern data/sample release aim to safeguard the confidentiality and privacy of cohort research participants (without whom there would be no data or samples) and enable the realization of societal benefit through optimizing the scientific use of those cohorts. Within collaborations involving multiple cohorts and biobanks, however, the local, national, and supranational institutional and legal guidelines for research (which produce a multiplicity of data access governance structures and guidelines) risk impeding the very science that is the raison d'etre of these consortia. We present an ethnographic study, which examined the epistemic and nonepistemic values driving decisions about data access and their consequences in the context of the pilot of an integrated approach to co-analysis of data. We demonstrate how the potential analytic flexibility offered by this approach was lost under contemporary data access governance. We identify three dominant values: protecting the research participant, protecting the study, and protecting the researcher. These values were both supported by and juxtaposed against a "public good" argument, and each was used as a rationale to both promote and inhibit sharing of data. While protection of the research participants was central to access permissions, decisions were also attentive to the desire of researchers to see their efforts in building population biobanks and cohorts realized in the form of scientific outputs. We conclude that systems for governing and enabling data access in large consortia need to (1) protect disclosure of research participant information or identity, (2) ensure the specific expectations of research participants are met, (3) embody systems of review that are transparent and not compromised by the specific interests of one particular group of stakeholders, and (4) facilitate data access procedures that are timely and efficient. Practical solutions are urgently needed. New approaches to data access governance should be trialed (and formally evaluated) with input from and discussion with stakeholders.

VSAT communications networks - An overview

NASA Astrophysics Data System (ADS)

Chakraborty, D.

1988-05-01

The very-small-aperture-terminal (VSAT) fixed satellite communication network is a star network in which many dispersed micro terminals attempt to send data in a packet form through a random access/time-division multiple-access (RA/TDMA) satellite channel with transmission delay. The basic concept of the VSAT and its service potential are discussed. Two classes of traffic are addressed, namely, business-oriented low-rate-data traffic and bulk data traffic of corporate networks. Satellite access, throughput, and delay are considered. The size of the network population that can be served in an RA/TDMA environment is calculated. User protocols are examined. A typical VSAT business scenario is described.

Conceptual framework of the Controlling Asthma in American Cities Project.

PubMed

Herman, Elizabeth Jane

2011-02-01

The Controlling Asthma in American Cities Project (CAACP) was designed to improve the control of asthma in inner-city populations of children with a disparate burden of symptoms and adverse outcomes. As with many chronic diseases, asthma is the manifestation of multiple biologic, environmental, and social determinants. In addition to appropriate medical management, individuals with asthma must have logistical, financial, and cultural access to environments that allow avoidance of asthma triggers and encourage good asthma management practices. In recognition of this complexity, the CAACP required the seven project sites to coordinate and synchronize multiple interventions (education, healthcare access, medical management, trigger reduction) at multiple levels (individual, home, school, community, and policy) through the collaboration of relevant groups, institutions, and individuals. This paper describes the "program theory" of the CAACP project-the assumptions about how the project worked, how the components were linked, and what outcomes were anticipated. It relates the subsequent papers in the supplement to the program theory and describes how the papers can inform and guide other community-based interventions, and advance the translation of scientific knowledge to effective interventions in communities of need.

Multilevel resistive information storage and retrieval

DOEpatents

Lohn, Andrew; Mickel, Patrick R.

2016-08-09

The present invention relates to resistive random-access memory (RRAM or ReRAM) systems, as well as methods of employing multiple state variables to form degenerate states in such memory systems. The methods herein allow for precise write and read steps to form multiple state variables, and these steps can be performed electrically. Such an approach allows for multilevel, high density memory systems with enhanced information storage capacity and simplified information retrieval.

Multi-pulse multi-delay (MPMD) multiple access modulation for UWB

DOEpatents

Dowla, Farid U.; Nekoogar, Faranak

2007-03-20

A new modulation scheme in UWB communications is introduced. This modulation technique utilizes multiple orthogonal transmitted-reference pulses for UWB channelization. The proposed UWB receiver samples the second order statistical function at both zero and non-zero lags and matches the samples to stored second order statistical functions, thus sampling and matching the shape of second order statistical functions rather than just the shape of the received pulses.

Access block in NSW hospitals, 1999-2001: does the definition matter?

PubMed

Forero, Roberto; Mohsin, Mohammed; Bauman, Adrian E; Ieraci, Sue; Young, Lis; Phung, Hai N; Hillman, Kenneth M; McCarthy, Sally M; Hugelmeyer, C David

2004-01-19

To estimate the magnitude of access block and its trend over time in New South Wales hospitals, using different definitions of access block, and to explore its association with clinical and non-clinical factors. An epidemiological study using the Emergency Department Information System datasets (1 January 1999 to 31 December 2001) from a sample of 55 NSW hospitals. Prevalence of access block measured by four different definitions; strength of association between access block, type of hospital, year of presentation, mode and time of arrival, triage category (an indicator of urgency), age and sex. Rates of access block (for all four definitions) increased between 1999 and 2001 by 1%-2% per year. There were increases across all regions of NSW, but urban regions in particular. Patients presenting to Principal Referral hospitals and those who arrived at night were more likely to experience access block. After adjusting for triage category and year of presentation, the mode of arrival, time of arrival, type of hospital, age and sex were significantly associated with access block. Access block continues to increase across NSW, whatever the definition used. We recommend that hospitals in NSW and Australia move to the use of one standard definition of access block, as our study suggests there is no significant additional information emerging from the use of multiple definitions.

Random access with adaptive packet aggregation in LTE/LTE-A.

PubMed

Zhou, Kaijie; Nikaein, Navid

While random access presents a promising solution for efficient uplink channel access, the preamble collision rate can significantly increase when massive number of devices simultaneously access the channel. To address this issue and improve the reliability of the random access, an adaptive packet aggregation method is proposed. With the proposed method, a device does not trigger a random access for every single packet. Instead, it starts a random access when the number of aggregated packets reaches a given threshold. This method reduces the packet collision rate at the expense of an extra latency, which is used to accumulate multiple packets into a single transmission unit. Therefore, the tradeoff between packet loss rate and channel access latency has to be carefully selected. We use semi-Markov model to derive the packet loss rate and channel access latency as functions of packet aggregation number. Hence, the optimal amount of aggregated packets can be found, which keeps the loss rate below the desired value while minimizing the access latency. We also apply for the idea of packet aggregation for power saving, where a device aggregates as many packets as possible until the latency constraint is reached. Simulations are carried out to evaluate our methods. We find that the packet loss rate and/or power consumption are significantly reduced with the proposed method.

An Effective Massive Sensor Network Data Access Scheme Based on Topology Control for the Internet of Things

PubMed Central

Yi, Meng; Chen, Qingkui; Xiong, Neal N.

2016-01-01

This paper considers the distributed access and control problem of massive wireless sensor networks’ data access center for the Internet of Things, which is an extension of wireless sensor networks and an element of its topology structure. In the context of the arrival of massive service access requests at a virtual data center, this paper designs a massive sensing data access and control mechanism to improve the access efficiency of service requests and makes full use of the available resources at the data access center for the Internet of things. Firstly, this paper proposes a synergistically distributed buffer access model, which separates the information of resource and location. Secondly, the paper divides the service access requests into multiple virtual groups based on their characteristics and locations using an optimized self-organizing feature map neural network. Furthermore, this paper designs an optimal scheduling algorithm of group migration based on the combination scheme between the artificial bee colony algorithm and chaos searching theory. Finally, the experimental results demonstrate that this mechanism outperforms the existing schemes in terms of enhancing the accessibility of service requests effectively, reducing network delay, and has higher load balancing capacity and higher resource utility rate. PMID:27827878

Pace: Privacy-Protection for Access Control Enforcement in P2P Networks

NASA Astrophysics Data System (ADS)

Sánchez-Artigas, Marc; García-López, Pedro

In open environments such as peer-to-peer (P2P) systems, the decision to collaborate with multiple users — e.g., by granting access to a resource — is hard to achieve in practice due to extreme decentralization and the lack of trusted third parties. The literature contains a plethora of applications in which a scalable solution for distributed access control is crucial. This fact motivates us to propose a protocol to enforce access control, applicable to networks consisting entirely of untrusted nodes. The main feature of our protocol is that it protects both sensitive permissions and sensitive policies, and does not rely on any centralized authority. We analyze the efficiency (computational effort and communication overhead) as well as the security of our protocol.

Design of Accelerator Online Simulator Server Using Structured Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Guobao; /Brookhaven; Chu, Chungming

2012-07-06

Model based control plays an important role for a modern accelerator during beam commissioning, beam study, and even daily operation. With a realistic model, beam behaviour can be predicted and therefore effectively controlled. The approach used by most current high level application environments is to use a built-in simulation engine and feed a realistic model into that simulation engine. Instead of this traditional monolithic structure, a new approach using a client-server architecture is under development. An on-line simulator server is accessed via network accessible structured data. With this approach, a user can easily access multiple simulation codes. This paper describesmore » the design, implementation, and current status of PVData, which defines the structured data, and PVAccess, which provides network access to the structured data.« less

Methodological proceedings to evaluate the physical accessibility in urban historic sites.

PubMed

Ribeiro, Gabriela Sousa; Martins, Laura Bezerra; Monteiro, Circe Maria Gama

2012-01-01

Historic urban sites are set by cultural and social diversities, generating multiple activities and use and access to these sites should be available to all people including those with disabilities. Taking into consideration that using the same methodology that was used in different historic sites researches with positive results facilitates replication, we aimed to develop methodological procedures that identify conditions of physical accessibility in open public spaces and access to public buildings in historic urban sites to support proposals about design requirements for improvements to the problems diagnosed and control inadequacies of the physical environment. The study methods and techniques from different areas of knowledge culminated in a proposal built with an emphasis on user participation that could be applied with low cost and in relatively short period of time.

Operational evaluation of a DGPS / SATCOM VTS : final report

DOT National Transportation Integrated Search

1996-09-01

Satellite communications (SATCOM) using code division multiple access(CDMA) modulation and burst messaging, provided a new dimension to communication channel capacity, operating dependability, and area of coverage. This technology, together with diff...

Personal Health Records - Multiple Languages

MedlinePlus

... Seattle and King County Spanish (español) Expand Section Personal Health Records: MedlinePlus Health Topic - English ... Subscribe to RSS Follow us Disclaimers Copyright Privacy Accessibility Quality Guidelines Viewers & Players MedlinePlus Connect for ...

Intersectionality and the LGBT Cancer Patient.

PubMed

Damaskos, Penny; Amaya, Beau; Gordon, RuthAnn; Walters, Chasity Burrows

2018-02-01

To present the ways in which race, ethnicity, class, gender, and sexual orientation interact in the context of cancer risk, access to care, and treatment by health care providers. Cancer risk factors, access to care, and treatment for lesbian, gay, bisexual, and transgender (LGBT) patients are discussed within the context of intersectionality and cultural humility. Peer reviewed articles, cancer organizations, and clinical practice. LGBT patients have multiple identities that intersect to create unique experiences. These experiences shape their interactions with the health care system with the potential for positive or negative consequences. More data is needed to describe the outcomes of those experiences and inform clinical practice. Oncology nurses have an obligation to acknowledge patients' multiple identities and use the practice of cultural humility to provide individualized, patient-centered care. Copyright © 2017 Elsevier Inc. All rights reserved.

Using Palm Technology in Participatory Simulations of Complex Systems: A New Take on Ubiquitous and Accessible Mobile Computing

NASA Astrophysics Data System (ADS)

Klopfer, Eric; Yoon, Susan; Perry, Judy

2005-09-01

This paper reports on teachers' perceptions of the educational affordances of a handheld application called Participatory Simulations. It presents evidence from five cases representing each of the populations who work with these computational tools. Evidence across multiple data sources yield similar results to previous research evaluations of handheld activities with respect to enhancing motivation, engagement and self-directed learning. Three additional themes are discussed that provide insight into understanding curricular applicability of Participatory Simulations that suggest a new take on ubiquitous and accessible mobile computing. These themes generally point to the multiple layers of social and cognitive flexibility intrinsic to their design: ease of adaptation to subject-matter content knowledge and curricular integration; facility in attending to teacher-individualized goals; and encouraging the adoption of learner-centered strategies.

The Galley Parallel File System

NASA Technical Reports Server (NTRS)

Nieuwejaar, Nils; Kotz, David

1996-01-01

As the I/O needs of parallel scientific applications increase, file systems for multiprocessors are being designed to provide applications with parallel access to multiple disks. Many parallel file systems present applications with a conventional Unix-like interface that allows the application to access multiple disks transparently. The interface conceals the parallelism within the file system, which increases the ease of programmability, but makes it difficult or impossible for sophisticated programmers and libraries to use knowledge about their I/O needs to exploit that parallelism. Furthermore, most current parallel file systems are optimized for a different workload than they are being asked to support. We introduce Galley, a new parallel file system that is intended to efficiently support realistic parallel workloads. We discuss Galley's file structure and application interface, as well as an application that has been implemented using that interface.

Evaluating IAIMS at Yale: information access.

PubMed

Grajek, S E; Calarco, P; Frawley, S J; McKay, J; Miller, P L; Paton, J A; Roderer, N K; Sullivan, J E

1997-01-01

To evaluate use of information resources during the first year of IAIMS implementation at the Yale-New Haven Medical Center. The evaluation asked: (1) Which information resources are being used? (2) Who uses information resources? (3) Where are information resources used? (4) Are multiple sources of information being integrated? Measures included monthly usage data for resources delivered network-wide, in the Medical Library, and in the Hospital; online surveys of library workstation users; an annual survey of a random, stratified sample of Medical Center faculty, postdoctoral trainees, students, nurses, residents, and managerial and professional staff; and user comments. Eighty-three percent of the Medical Center community use networked information resources, and use of resources is increasing. Both status (faculty, student, nurse, etc.) and mission (teaching, research, patient care) affect use of individual resources. Eighty-eight percent of people use computers in more than one location, and increases in usage of traditional library resources such as MEDLINE are due to increased access from outside the Library. Both survey and usage data suggest that people are using multiple resources during the same information seeking session. Almost all of the Medical Center community is using networked information resources in more settings. It is necessary to support increased demand for information access from remote locations and to specific populations, such as nurses. People are integrating information from multiple sources, but true integration within information systems is just beginning. Other institutions are advised to incorporate pragmatic evaluation into their IAIMS activities and to share evaluation results with decision-makers.

Efficiently sphere-decodable physical layer transmission schemes for wireless storage networks

NASA Astrophysics Data System (ADS)

Lu, Hsiao-Feng Francis; Barreal, Amaro; Karpuk, David; Hollanti, Camilla

2016-12-01

Three transmission schemes over a new type of multiple-access channel (MAC) model with inter-source communication links are proposed and investigated in this paper. This new channel model is well motivated by, e.g., wireless distributed storage networks, where communication to repair a lost node takes place from helper nodes to a repairing node over a wireless channel. Since in many wireless networks nodes can come and go in an arbitrary manner, there must be an inherent capability of inter-node communication between every pair of nodes. Assuming that communication is possible between every pair of helper nodes, the newly proposed schemes are based on various smart time-sharing and relaying strategies. In other words, certain helper nodes will be regarded as relays, thereby converting the conventional uncooperative multiple-access channel to a multiple-access relay channel (MARC). The diversity-multiplexing gain tradeoff (DMT) of the system together with efficient sphere-decodability and low structural complexity in terms of the number of antennas required at each end is used as the main design objectives. While the optimal DMT for the new channel model is fully open, it is shown that the proposed schemes outperform the DMT of the simple time-sharing protocol and, in some cases, even the optimal uncooperative MAC DMT. While using a wireless distributed storage network as a motivating example throughout the paper, the MAC transmission techniques proposed here are completely general and as such applicable to any MAC communication with inter-source communication links.

The NCAR Research Data Archive's Hybrid Approach for Data Discovery and Access

NASA Astrophysics Data System (ADS)

Schuster, D.; Worley, S. J.

2013-12-01

The NCAR Research Data Archive (RDA http://rda.ucar.edu) maintains a variety of data discovery and access capabilities for it's 600+ dataset collections to support the varying needs of a diverse user community. In-house developed and standards-based community tools offer services to more than 10,000 users annually. By number of users the largest group is external and access the RDA through web based protocols; the internal NCAR HPC users are fewer in number, but typically access more data volume. This paper will detail the data discovery and access services maintained by the RDA to support both user groups, and show metrics that illustrate how the community is using the services. The distributed search capability enabled by standards-based community tools, such as Geoportal and an OAI-PMH access point that serves multiple metadata standards, provide pathways for external users to initially discover RDA holdings. From here, in-house developed web interfaces leverage primary discovery level metadata databases that support keyword and faceted searches. Internal NCAR HPC users, or those familiar with the RDA, may go directly to the dataset collection of interest and refine their search based on rich file collection metadata. Multiple levels of metadata have proven to be invaluable for discovery within terabyte-sized archives composed of many atmospheric or oceanic levels, hundreds of parameters, and often numerous grid and time resolutions. Once users find the data they want, their access needs may vary as well. A THREDDS data server running on targeted dataset collections enables remote file access through OPENDAP and other web based protocols primarily for external users. In-house developed tools give all users the capability to submit data subset extraction and format conversion requests through scalable, HPC based delayed mode batch processing. Users can monitor their RDA-based data processing progress and receive instructions on how to access the data when it is ready. External users are provided with RDA server generated scripts to download the resulting request output. Similarly they can download native dataset collection files or partial files using Wget or cURL based scripts supplied by the RDA server. Internal users can access the resulting request output or native dataset collection files directly from centralized file systems.

Epistemological Access through Lecture Materials in Multiple Modes and Language Varieties: The Role of Ideologies and Multilingual Literacy Practices in Student Evaluations of Such Materials at a South African University

ERIC Educational Resources Information Center

Antia, Bassey E.; Dyers, Charlyn

2016-01-01

This paper seeks to address the ways in which ideology and literacy practices shape the responses of students to an ongoing initiative at the University of the Western Cape aimed at diversifying options for epistemological access, specifically the language varieties and the modes in which parts of the curriculum for a third year linguistics module…

Intersystem Interference Reduction for Overlaid HAPS-Terrestrial CDMA System

NASA Astrophysics Data System (ADS)

Huang, Jeng-Ji; Wang, Wei-Ting; Li, Mingfu; Shiung, David; Ferng, Huei-Wen

In this letter, we propose that directional antennas, combined with power management, be incorporated to reduce intersystem interference in a shared band overlaid high altitude platform station (HAPS)-terrestrial code division multiple access (CDMA) system. To eliminate the HAPS to terrestrial interference, the HAPS is accessed only via directional antennas under the proposed scheme. By doing so, the uplink power to the HAPS can accordingly be increased, so that the terrestrial to HAPS interference is also effectively suppressed.

Concepts for a global resources information system

NASA Technical Reports Server (NTRS)

Billingsley, F. C.; Urena, J. L.

1984-01-01

The objective of the Global Resources Information System (GRIS) is to establish an effective and efficient information management system to meet the data access requirements of NASA and NASA-related scientists conducting large-scale, multi-disciplinary, multi-mission scientific investigations. Using standard interfaces and operating guidelines, diverse data systems can be integrated to provide the capabilities to access and process multiple geographically dispersed data sets and to develop the necessary procedures and algorithms to derive global resource information.

The Use of Digital and Remote Communication Technologies as a Tool for Multiple Sclerosis Management: Narrative Review

PubMed Central

Marziniak, Martin; Brichetto, Giampaolo; Feys, Peter; Meyding-Lamadé, Uta; Vernon, Karen

2018-01-01

Despite recent advances in multiple sclerosis (MS) care, many patients only infrequently access health care services, or are unable to access them easily, for reasons such as mobility restrictions, travel costs, consultation and treatment time constraints, and a lack of locally available MS expert services. Advances in mobile communications have led to the introduction of electronic health (eHealth) technologies, which are helping to improve both access to and the quality of health care services. As the Internet is now readily accessible through smart mobile devices, most people can take advantage of eHealth apps. The development of digital applications and remote communication technologies for patients with MS has increased rapidly in recent years. These apps are intended to complement traditional in-clinic approaches and can bring significant benefits to both patients with MS and health care providers (HCPs). For patients, such eHealth apps have been shown to improve outcomes and increase access to care, disease information, and support. These apps also help patients to participate actively in self-management, for example, by tracking adherence to treatment, changes in bladder and bowel habits, and activity and mood. For HCPs, MS eHealth solutions can simplify the multidisciplinary approaches needed to tailor MS management strategies to individual patients; facilitate remote monitoring of patient symptoms, adverse events, and outcomes; enable the efficient use of limited resources and clinic time; and potentially allow more timely intervention than is possible with scheduled face-to-face visits. These benefits are important because MS is a long-term, multifaceted chronic condition that requires ongoing monitoring, assessment, and management. We identified in the literature 28 eHealth solutions for patients with MS that fall within the four categories of screening and assessment, disease monitoring and self-management, treatment and rehabilitation, and advice and education. We review each solution, focusing on any clinical evidence supporting their use from prospective trials (including ASSESS MS, Deprexis, MSdialog, and the Multiple Sclerosis Performance Test) and consider the opportunities, barriers to adoption, and potential pitfalls of eHealth technologies in routine health care. PMID:29691208

Teaching individuals with intellectual disability to email across multiple device platforms.

PubMed

Cihak, David F; McMahon, Donald; Smith, Cate C; Wright, Rachel; Gibbons, Melinda M

2014-11-20

The purpose of this study was to examine the use of email by people with intellectual disability across multiple technological devices or platforms. Four individuals with intellectual disability participated in this study. Participants were taught how to access and send an email on a Windows desktop computer, laptop, and an iPad tablet device. Results indicated a functional relation. All participants acquired and generalized sending and receiving an email from multiple platforms. Conclusions are discussed about the importance of empowering people with intellectual disability by providing multiple means of expression, including the ability to communicate effectively using a variety of devices. Copyright © 2014 Elsevier Ltd. All rights reserved.

A primer on intraosseous access: History, clinical considerations, and current devices.

PubMed

Burgert, James M

2016-01-01

Intraosseous (IO) access is a method recommended by the American Heart Association and the European Resuscitation Council to administer resuscitative drugs and fluids when intravenous (IV) access cannot be rapidly or easily obtained. Many clinicians have limited knowledge or experience with the IO route. The purpose of this review was to provide the reader with a succinct review of the history, clinical considerations, and devices associated with IO access. Narrative review. University-based academic research cell. Not applicable. Not applicable. IO access is a lifesaving bridge to definitive vascular access that may be considered when an IV cannot be rapidly attained and the patient's outcome may be negatively affected without prompt circulatory access. The IO route has few contraindications for use and a low rate of serious complications. Multiple manual and powered devices that may be placed in several anatomic sites are commercially available. All clinicians who provide acute care or respond to cardiovascular emergencies should obtain training and maintain proficiency in placing and using IO devices as the IO route is recommended by the major resuscitation organizations as the preferred route of infusion when rapid, reliable IV access is unavailable.

Ubiquitous Accessibility for People with Visual Impairments: Are We There Yet?

PubMed

Billah, Syed Masum; Ashok, Vikas; Porter, Donald E; Ramakrishnan, I V

2017-05-01

Ubiquitous access is an increasingly common vision of computing, wherein users can interact with any computing device or service from anywhere, at any time. In the era of personal computing, users with visual impairments required special-purpose, assistive technologies, such as screen readers, to interact with computers. This paper investigates whether technologies like screen readers have kept pace with, or have created a barrier to, the trend toward ubiquitous access, with a specific focus on desktop computing as this is still the primary way computers are used in education and employment. Towards that, the paper presents a user study with 21 visually-impaired participants, specifically involving the switching of screen readers within and across different computing platforms, and the use of screen readers in remote access scenarios. Among the findings, the study shows that, even for remote desktop access-an early forerunner of true ubiquitous access-screen readers are too limited, if not unusable. The study also identifies several accessibility needs, such as uniformity of navigational experience across devices, and recommends potential solutions. In summary, assistive technologies have not made the jump into the era of ubiquitous access, and multiple, inconsistent screen readers create new practical problems for users with visual impairments.

Toward Proper Authentication Methods in Electronic Medical Record Access Compliant to HIPAA and C.I.A. Triangle.

PubMed

Tipton, Stephen J; Forkey, Sara; Choi, Young B

2016-04-01

This paper examines various methods encompassing the authentication of users in accessing Electronic Medical Records (EMRs). From a methodological perspective, multiple authentication methods have been researched from both a desktop and mobile accessibility perspective. Each method is investigated at a high level, along with comparative analyses, as well as real world examples. The projected outcome of this examination is a better understanding of the sophistication required in protecting the vital privacy constraints of an individual's Protected Health Information (PHI). In understanding the implications of protecting healthcare data in today's technological world, the scope of this paper is to grasp an overview of confidentiality as it pertains to information security. In addressing this topic, a high level overview of the three goals of information security are examined; in particular, the goal of confidentiality is the primary focus. Expanding upon the goal of confidentiality, healthcare accessibility legal aspects are considered, with a focus upon the Health Insurance Portability and Accountability Act of 1996 (HIPAA). With the primary focus of this examination being access to EMRs, the paper will consider two types of accessibility of concern: access from a physician, or group of physicians; and access from an individual patient.

NOTES performed using multiple ports of entry: Current experience and potential implications for urologic applications.

PubMed

Lima, Estevao; Rolanda, Carla; Correia-Pinto, Jorge

2009-05-01

An isolated transgastric port raises serious limitations in performing natural orifice translumenal endoscopic surgery (NOTES) complex procedures in the urology field. In an attempt to overcome these limitations, several solutions has been advanced, such as the hybrid approach (adding a single abdominal port access) or the pure NOTES combined approach (joining multiple natural orifice ports). To review the current state of experimental and clinical results of multiple ports in NOTES, a literature search of PubMed was performed, seeking publications from January 2002 to 2008 on NOTES. In addition, we looked at pertinent abstracts of annual meetings of the American Urological Association, the European Association of Urology, and the World Congress of Endourology from 2007. Multiple ports of entry seem to be necessary, mainly for moderately complex procedures. Thus, we could find studies using the hybrid approach (combination of transgastric or transvaginal access with a single transabdominal port), or using the pure NOTES combined approach (transgastric and transvesical, transvaginal and transcolonic, or transgastric and transvaginal). There is still limited experience in humans using these approaches, and no comparative studies exist to date. It is predictable that for moderately complex procedures, we will need multiple ports, so the transvaginal-transabdominal (hybrid) approach is the most appealing, whereas in a pure NOTES perspective, the transgastric-transvesical approach seems to be the preferred approach. We are waiting for new equipment and instruments that are more appropriate for these novel techniques.

Handling a Collection of PDF Documents

EPA Pesticide Factsheets

You have several options for making a large collection of PDF documents more accessible to your audience: avoid uploading altogether, use multiple document pages, and use document IDs as anchors for direct links within a document page.

Sampling and estimating recreational use.

Treesearch

Timothy G. Gregoire; Gregory J. Buhyoff

1999-01-01

Probability sampling methods applicable to estimate recreational use are presented. Both single- and multiple-access recreation sites are considered. One- and two-stage sampling methods are presented. Estimation of recreational use is presented in a series of examples.

Multiple attractors and dynamics in an OLG model with productive environment

NASA Astrophysics Data System (ADS)

Caravaggio, Andrea; Sodini, Mauro

2018-05-01

This work analyses an overlapping generations model in which economic activity depends on the exploitation of a free-access natural resource. In addition, public expenditures for environmental maintenance are assumed. By characterising some properties of the map and performing numerical simulations, we investigate consequences of the interplay between environmental public expenditure and private sector. In particular, we identify different scenarios in which multiple equilibria as well as complex dynamics may arise.

Knowledge Acquisition for Application: Cognitive Flexibility and Transfer of Training in III-Structured Domains

DTIC Science & Technology

1992-04-01

Derivabl, from Concentrated Conceotual Analysis Obviously, there is a prima facie medical relevance to studying concepts judged by the medical community... consumers of research, e.g., students, see and are affected only by the partial products of the overall quest, without access to the "big picture...in a number of studies that the learning of complex content materia ! in ill-structured domains requires multiple representations -- multiple

Sociocultural variables in youth access to tobacco: replication 5 years later.

PubMed

Landrine, H; Klonoff, E A; Campbell, R; Reina-Patton, A

2000-05-01

A prior study presented the only systematic investigation of the role of sociocultural variables in youth access to tobacco. White, black, and Latino girls and boys attempted to purchase cigarettes in the same 72 stores at the same time of day. Results revealed significantly greater sales to girls than to boys and to minorities than to whites. Before concluding that sociocultural variables must be addressed in merchant intervention programs designed to reduce youth access to tobacco, this study must be replicated, particularly in light of the significant decreases in youth access in the past 5 years. This article presents that replication. The stores used in the prior study were selected, and 12 white, black, and Latino girls and boys attempted to purchase cigarettes in those stores at the same time of day. Results Youths' access rate in 1999 (12.7%) was significantly lower than in the prior (1993-1995) study (41%). No effect for minors' gender was found, but the ethnicity effect again emerged: Black and Latino youth were 2.5 times more likely to be sold cigarettes than their white counterparts. Multiple sociocultural variables affect youth access to tobacco when access rates are high, but only youth ethnicity plays a role when access rates are low. Merchant interventions designed to reduce youth access to tobacco must address ethnic issues.

Linking Fine-Scale Observations and Model Output with Imagery at Multiple Scales

NASA Astrophysics Data System (ADS)

Sadler, J.; Walthall, C. L.

2014-12-01

The development and implementation of a system for seasonal worldwide agricultural yield estimates is underway with the international Group on Earth Observations GeoGLAM project. GeoGLAM includes a research component to continually improve and validate its algorithms. There is a history of field measurement campaigns going back decades to draw upon for ways of linking surface measurements and model results with satellite observations. Ground-based, in-situ measurements collected by interdisciplinary teams include yields, model inputs and factors affecting scene radiation. Data that is comparable across space and time with careful attention to calibration is essential for the development and validation of agricultural applications of remote sensing. Data management to ensure stewardship, availability and accessibility of the data are best accomplished when considered an integral part of the research. The expense and logistical challenges of field measurement campaigns can be cost-prohibitive and because of short funding cycles for research, access to consistent, stable study sites can be lost. The use of a dedicated staff for baseline data needed by multiple investigators, and conducting measurement campaigns using existing measurement networks such as the USDA Long Term Agroecosystem Research network can fulfill these needs and ensure long-term access to study sites.

Multiradio Resource Management: Parallel Transmission for Higher Throughput?

NASA Astrophysics Data System (ADS)

Bazzi, Alessandro; Pasolini, Gianni; Andrisano, Oreste

2008-12-01

Mobile communication systems beyond the third generation will see the interconnection of heterogeneous radio access networks (UMTS, WiMax, wireless local area networks, etc.) in order to always provide the best quality of service (QoS) to users with multimode terminals. This scenario poses a number of critical issues, which have to be faced in order to get the best from the integrated access network. In this paper, we will investigate the issue of parallel transmission over multiple radio access technologies (RATs), focusing the attention on the QoS perceived by final users. We will show that the achievement of a real benefit from parallel transmission over multiple RATs is conditioned to the fulfilment of some requirements related to the kind of RATs, the multiradio resource management (MRRM) strategy, and the transport-level protocol behaviour. All these aspects will be carefully considered in our investigation, which will be carried out partly adopting an analytical approach and partly by means of simulations. In this paper, in particular, we will propose a simple but effective MRRM algorithm, whose performance will be investigated in IEEE802.11a-UMTS and IEEE802.11a-IEEE802.16e heterogeneous networks (adopted as case studies).

Health seeking behaviours among electronic waste workers in Ghana.

PubMed

Asampong, Emmanuel; Dwuma-Badu, Kwaku; Stephens, Judith; Srigboh, Roland; Neitzel, Richard; Basu, Niladri; Fobil, Julius N

2015-10-16

Electronic waste workers are prone to various illnesses and injuries from numerous hazards thus the need for them to seek health care. The aim of this study was to describe health-seeking behavior, and social and other factors affecting this behavior, among electronic waste workers at Agbogbloshie, Accra, Ghana. In-depth interviews were conducted and analyzed qualitatively from a grounded theory perspective. Workers experienced various kinds of ailments. These included physical injuries, chest and respiratory tract associated symptoms, malaria, headaches, body pains and stomach discomfort. They reported seeking health care from multiple sources, and the main determinants of health seeking behaviour were severity of illness, perceived benefit of treatment, accessibility of service, quality of service, ease of communication with service provider and cost of health care. Multiple sources of health care were used by the e-waste workers. As cost was a major barrier to accessing formal health care, most of the workers did not subscribe to health insurance. Since enrollment in health insurance is low amongst the workers, education campaigns on the need to register with the National Health Insurance Scheme would facilitate access to formal health care and could result in improved health outcomes among e-waste workers.

CCDST: A free Canadian climate data scraping tool

NASA Astrophysics Data System (ADS)

Bonifacio, Charmaine; Barchyn, Thomas E.; Hugenholtz, Chris H.; Kienzle, Stefan W.

2015-02-01

In this paper we present a new software tool that automatically fetches, downloads and consolidates climate data from a Web database where the data are contained on multiple Web pages. The tool is called the Canadian Climate Data Scraping Tool (CCDST) and was developed to enhance access and simplify analysis of climate data from Canada's National Climate Data and Information Archive (NCDIA). The CCDST deconstructs a URL for a particular climate station in the NCDIA and then iteratively modifies the date parameters to download large volumes of data, remove individual file headers, and merge data files into one output file. This automated sequence enhances access to climate data by substantially reducing the time needed to manually download data from multiple Web pages. To this end, we present a case study of the temporal dynamics of blowing snow events that resulted in ~3.1 weeks time savings. Without the CCDST, the time involved in manually downloading climate data limits access and restrains researchers and students from exploring climate trends. The tool is coded as a Microsoft Excel macro and is available to researchers and students for free. The main concept and structure of the tool can be modified for other Web databases hosting geophysical data.

Comprehensive security framework for the communication and storage of medical images

NASA Astrophysics Data System (ADS)

Slik, David; Montour, Mike; Altman, Tym

2003-05-01

Confidentiality, integrity verification and access control of medical imagery and associated metadata is critical for the successful deployment of integrated healthcare networks that extend beyond the department level. As medical imagery continues to become widely accessed across multiple administrative domains and geographically distributed locations, image data should be able to travel and be stored on untrusted infrastructure, including public networks and server equipment operated by external entities. Given these challenges associated with protecting large-scale distributed networks, measures must be taken to protect patient identifiable information while guarding against tampering, denial of service attacks, and providing robust audit mechanisms. The proposed framework outlines a series of security practices for the protection of medical images, incorporating Transport Layer Security (TLS), public and secret key cryptography, certificate management and a token based trusted computing base. It outlines measures that can be utilized to protect information stored within databases, online and nearline storage, and during transport over trusted and untrusted networks. In addition, it provides a framework for ensuring end-to-end integrity of image data from acquisition to viewing, and presents a potential solution to the challenges associated with access control across multiple administrative domains and institution user bases.

Tunneling and Origin of Large Access Resistance in Layered-Crystal Organic Transistors

NASA Astrophysics Data System (ADS)

Hamai, Takamasa; Arai, Shunto; Minemawari, Hiromi; Inoue, Satoru; Kumai, Reiji; Hasegawa, Tatsuo

2017-11-01

Layered crystallinity of organic semiconductors is crucial to obtaining high-performance organic thin-film transistors (OTFTs), as it allows both smooth-channel-gate-insulator interface formation and efficient two-dimensional carrier transport along the interface. However, the role of vertical transport across the crystalline molecular layers in device operations has not been a crucial subject so far. Here, we show that the interlayer carrier transport causes unusual nonlinear current-voltage characteristics and enormous access resistance in extremely high-quality single-crystal OTFTs based on 2-decyl-7-phenyl[1]-benzothieno[3 ,2 -b ][1]benzothiophene (Ph -BTBT -C10 ) that involve inherent multiple semiconducting π -conjugated layers interposed, respectively, by electrically inert alkyl-chain layers. The output characteristics present layer-number (n )-dependent nonlinearity that becomes more evident at larger n (1 ≤n ≤15 ), demonstrating tunneling across multiple alkyl-chain layers. The n -dependent device mobility and four-probe measurements reveal that the alkyl-chain layers generate a large access resistance that suppresses the device mobility from the intrinsic value of about 20 cm2 V-1 s-1 . Our findings clarify the reason why device characteristics are distributed in single-crystal OTFTs.

One Size Does Not Fit All: Using Qualitative Methods to Inform the Development of an Internet Portal for Multiple Sclerosis Patients

PubMed Central

Atreja, Ashish; Mehta, Neil; Miller, Deborah; Moore, Shirley; Nichols, Karen; Miller, Holly; Harris, C Martin

2005-01-01

Disabled and elderly populations are the fastest growing segment of Internet usage. However, these people face an “Inverse Information law”- access to appropriate information is particularly difficult to those who need it the most. Our tertiary care Multiple Sclerosis (MS) center received funding to develop a MS specific patient portal linked to web messaging system so as to empower patients to become more active participants in their health care. In order to design an effective portal, we conducted a qualitative study using focus groups and direct observation techniques. The study explores the perceptions, expectations and interactions of MS patients with the portal and underscores the many challenges MS patients face in getting quality health information on the Internet. Many of the patient barriers were due to inappropriate font sizes, low contrast, cluttering of web page and use of dynamic and flashing objects. Some of these issues are not addressed by Section 508 accessibility guidelines. We believe that any future patient portal or health information web site needs to address these issues and educate the patients about accessibility options to enhance utilization and user satisfaction. PMID:16778993

An Adaptive OFDMA-Based MAC Protocol for Underwater Acoustic Wireless Sensor Networks

PubMed Central

Khalil, Issa M.; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

2012-01-01

Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols. PMID:23012517

An adaptive OFDMA-based MAC protocol for underwater acoustic wireless sensor networks.

PubMed

Khalil, Issa M; Gadallah, Yasser; Hayajneh, Mohammad; Khreishah, Abdallah

2012-01-01

Underwater acoustic wireless sensor networks (UAWSNs) have many applications across various civilian and military domains. However, they suffer from the limited available bandwidth of acoustic signals and harsh underwater conditions. In this work, we present an Orthogonal Frequency Division Multiple Access (OFDMA)-based Media Access Control (MAC) protocol that is configurable to suit the operating requirements of the underwater sensor network. The protocol has three modes of operation, namely random, equal opportunity and energy-conscious modes of operation. Our MAC design approach exploits the multi-path characteristics of a fading acoustic channel to convert it into parallel independent acoustic sub-channels that undergo flat fading. Communication between node pairs within the network is done using subsets of these sub-channels, depending on the configurations of the active mode of operation. Thus, the available limited bandwidth gets fully utilized while completely avoiding interference. We derive the mathematical model for optimal power loading and subcarrier selection, which is used as basis for all modes of operation of the protocol. We also conduct many simulation experiments to evaluate and compare our protocol with other Code Division Multiple Access (CDMA)-based MAC protocols.

An improved ATAC-seq protocol reduces background and enables interrogation of frozen tissues.

PubMed

Corces, M Ryan; Trevino, Alexandro E; Hamilton, Emily G; Greenside, Peyton G; Sinnott-Armstrong, Nicholas A; Vesuna, Sam; Satpathy, Ansuman T; Rubin, Adam J; Montine, Kathleen S; Wu, Beijing; Kathiria, Arwa; Cho, Seung Woo; Mumbach, Maxwell R; Carter, Ava C; Kasowski, Maya; Orloff, Lisa A; Risca, Viviana I; Kundaje, Anshul; Khavari, Paul A; Montine, Thomas J; Greenleaf, William J; Chang, Howard Y

2017-10-01

We present Omni-ATAC, an improved ATAC-seq protocol for chromatin accessibility profiling that works across multiple applications with substantial improvement of signal-to-background ratio and information content. The Omni-ATAC protocol generates chromatin accessibility profiles from archival frozen tissue samples and 50-μm sections, revealing the activities of disease-associated DNA elements in distinct human brain structures. The Omni-ATAC protocol enables the interrogation of personal regulomes in tissue context and translational studies.

Method and apparatus of prefetching streams of varying prefetch depth

DOEpatents

Gara, Alan [Mount Kisco, NY; Ohmacht, Martin [Yorktown Heights, NY; Salapura, Valentina [Chappaqua, NY; Sugavanam, Krishnan [Mahopac, NY; Hoenicke, Dirk [Seebruck-Seeon, DE

2012-01-24

Method and apparatus of prefetching streams of varying prefetch depth dynamically changes the depth of prefetching so that the number of multiple streams as well as the hit rate of a single stream are optimized. The method and apparatus in one aspect monitor a plurality of load requests from a processing unit for data in a prefetch buffer, determine an access pattern associated with the plurality of load requests and adjust a prefetch depth according to the access pattern.

Multiple Phase Transitions in the Culture Dissemination

NASA Astrophysics Data System (ADS)

Wang, Bing; Han, Yuexing; Chen, Luonan; Aihara, Kazuyuki

We study the coevolution process in the Axelrod’s model with the consideration of agents’ abilities to access to the information. With a parameter to control the ability of communication, we observe two kinds of phase transitions both for cultural domains and network fragments, respectively. With the simulation results, we find the relationship between the critical value and the controlled parameter. The results indicate that the powerful ability to access to the information benefits the dissemination of culture in the system.

Data Processing for NASA's TDRSS DAMA Channel

NASA Technical Reports Server (NTRS)

Long, Christopher C.; Horan, Stephen

1996-01-01

A concept for the addition of a Demand Assignment Multiple Access (DAMA) service to NASA's current Space Network (SN) is developed. Specifically, the design of a receiver for the DAMA channel is outlined. Also, an outline of the procedures taken to process the received service request is presented. The modifications to the (SN) system are minimal. The post reception processing is accomplished using standard commercial off the shelf (COTS) packages. The result is a random access system capable of receiving requests for service.

Response to health inequity: the role of social protection in reducing poverty and achieving equity.

PubMed

Scheil-Adlung, Xenia

2014-06-01

Health inequities are determined by multiple factors within the health sector and beyond. While gaps in social health protection coverage and effective access to health care are among the most prominent causes of health inequities, social and economic inequalities existing beyond the health sector contribute greatly to barriers to access affordable and acceptable health care. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Enterprise systems security management: a framework for breakthrough protection

NASA Astrophysics Data System (ADS)

Farroha, Bassam S.; Farroha, Deborah L.

2010-04-01

Securing the DoD information network is a tremendous task due to its size, access locations and the amount of network intrusion attempts on a daily basis. This analysis investigates methods/architecture options to deliver capabilities for secure information sharing environment. Crypto-binding and intelligent access controls are basic requirements for secure information sharing in a net-centric environment. We introduce many of the new technology components to secure the enterprise. The cooperative mission requirements lead to developing automatic data discovery and data stewards granting access to Cross Domain (CD) data repositories or live streaming data. Multiple architecture models are investigated to determine best-of-breed approaches including SOA and Private/Public Clouds.

Accessing and Visualizing scientific spatiotemporal data

NASA Technical Reports Server (NTRS)

Katz, Daniel S.; Bergou, Attila; Berriman, Bruce G.; Block, Gary L.; Collier, Jim; Curkendall, David W.; Good, John; Husman, Laura; Jacob, Joseph C.; Laity, Anastasia;

Climate change, livelihoods and the multiple determinants of water adequacy: two approaches at regional to global scale

NASA Astrophysics Data System (ADS)

Lissner, Tabea; Reusser, Dominik

2015-04-01

Inadequate access to water is already a problem in many regions of the world and processes of global change are expected to further exacerbate the situation. Many aspects determine the adequacy of water resources: beside actual physical water stress, where the resource itself is limited, economic and social water stress can be experienced if access to resource is limited by inadequate infrastructure, political or financial constraints. To assess the adequacy of water availability for human use, integrated approaches are needed that allow to view the multiple determinants in conjunction and provide sound results as a basis for informed decisions. This contribution proposes two parts of an integrated approach to look at the multiple dimensions of water scarcity at regional to global scale. These were developed in a joint project with the German Development Agency (GIZ). It first outlines the AHEAD approach to measure Adequate Human livelihood conditions for wEll-being And Development, implemented at global scale and at national resolution. This first approach allows viewing impacts of climate change, e.g. changes in water availability, within the wider context of AHEAD conditions. A specific focus lies on the uncertainties in projections of climate change and future water availability. As adequate water access is not determined by water availability alone, in a second step we develop an approach to assess the water requirements for different sectors in more detail, including aspects of quantity, quality as well as access, in an integrated way. This more detailed approach is exemplified at region-scale in Indonesia and South Africa. Our results show that in many regions of the world, water scarcity is a limitation to AHEAD conditions in many countries, regardless of differing modelling output. The more detailed assessments highlight the relevance of additional aspects to assess the adequacy of water for human use, showing that in many regions, quality and infrastructure are the main limitations to water security.

Enabling Data Intensive Science through Service Oriented Science: Virtual Laboratories and Science Gateways

NASA Astrophysics Data System (ADS)

Lescinsky, D. T.; Wyborn, L. A.; Evans, B. J. K.; Allen, C.; Fraser, R.; Rankine, T.

2014-12-01

We present collaborative work on a generic, modular infrastructure for virtual laboratories (VLs, similar to science gateways) that combine online access to data, scientific code, and computing resources as services that support multiple data intensive scientific computing needs across a wide range of science disciplines. We are leveraging access to 10+ PB of earth science data on Lustre filesystems at Australia's National Computational Infrastructure (NCI) Research Data Storage Infrastructure (RDSI) node, co-located with NCI's 1.2 PFlop Raijin supercomputer and a 3000 CPU core research cloud. The development, maintenance and sustainability of VLs is best accomplished through modularisation and standardisation of interfaces between components. Our approach has been to break up tightly-coupled, specialised application packages into modules, with identified best techniques and algorithms repackaged either as data services or scientific tools that are accessible across domains. The data services can be used to manipulate, visualise and transform multiple data types whilst the scientific tools can be used in concert with multiple scientific codes. We are currently designing a scalable generic infrastructure that will handle scientific code as modularised services and thereby enable the rapid/easy deployment of new codes or versions of codes. The goal is to build open source libraries/collections of scientific tools, scripts and modelling codes that can be combined in specially designed deployments. Additional services in development include: provenance, publication of results, monitoring, workflow tools, etc. The generic VL infrastructure will be hosted at NCI, but can access alternative computing infrastructures (i.e., public/private cloud, HPC).The Virtual Geophysics Laboratory (VGL) was developed as a pilot project to demonstrate the underlying technology. This base is now being redesigned and generalised to develop a Virtual Hazards Impact and Risk Laboratory (VHIRL); any enhancements and new capabilities will be incorporated into a generic VL infrastructure. At same time, we are scoping seven new VLs and in the process, identifying other common components to prioritise and focus development.

The D3 Middleware Architecture

NASA Technical Reports Server (NTRS)

Walton, Joan; Filman, Robert E.; Korsmeyer, David J.; Lee, Diana D.; Mak, Ron; Patel, Tarang

2002-01-01

DARWIN is a NASA developed, Internet-based system for enabling aerospace researchers to securely and remotely access and collaborate on the analysis of aerospace vehicle design data, primarily the results of wind-tunnel testing and numeric (e.g., computational fluid-dynamics) model executions. DARWIN captures, stores and indexes data; manages derived knowledge (such as visualizations across multiple datasets); and provides an environment for designers to collaborate in the analysis of test results. DARWIN is an interesting application because it supports high-volumes of data. integrates multiple modalities of data display (e.g., images and data visualizations), and provides non-trivial access control mechanisms. DARWIN enables collaboration by allowing not only sharing visualizations of data, but also commentary about and views of data. Here we provide an overview of the architecture of D3, the third generation of DARWIN. Earlier versions of DARWIN were characterized by browser-based interfaces and a hodge-podge of server technologies: CGI scripts, applets, PERL, and so forth. But browsers proved difficult to control, and a proliferation of computational mechanisms proved inefficient and difficult to maintain. D3 substitutes a pure-Java approach for that medley: A Java client communicates (though RMI over HTTPS) with a Java-based application server. Code on the server accesses information from JDBC databases, distributed LDAP security services, and a collaborative information system. D3 is a three tier-architecture, but unlike 'E-commerce' applications, the data usage pattern suggests different strategies than traditional Enterprise Java Beans - we need to move volumes of related data together, considerable processing happens on the client, and the 'business logic' on the server-side is primarily data integration and collaboration. With D3, we are extending DARWIN to handle other data domains and to be a distributed system, where a single login allows a user transparent access to test results from multiple servers and authority domains.

Handling a Large Collection of PDF Documents

EPA Pesticide Factsheets

You have several options for making a large collection of PDF documents more accessible to your audience: avoid uploading altogether, use multiple document pages, and use document IDs as anchors for direct links within a document page.

SEER*Stat Software

Cancer.gov

If you have access to SEER Research Data, use SEER*Stat to analyze SEER and other cancer-related databases. View individual records and produce statistics including incidence, mortality, survival, prevalence, and multiple primary. Tutorials and related analytic software tools are available.

On Transform Domain Communication Systems under Spectrum Sensing Mismatch: A Deterministic Analysis.

PubMed

Jin, Chuanxue; Hu, Su; Huang, Yixuan; Luo, Qu; Huang, Dan; Li, Yi; Gao, Yuan; Cheng, Shaochi

2017-07-08

Towards the era of mobile Internet and the Internet of Things (IoT), numerous sensors and devices are being introduced and interconnected. To support such an amount of data traffic, traditional wireless communication technologies are facing challenges both in terms of the increasing shortage of spectrum resources and massive multiple access. The transform-domain communication system (TDCS) is considered as an alternative multiple access system, where 5G and mobile IoT are mainly focused. However, previous studies about TDCS are under the assumption that the transceiver has the global spectrum information, without the consideration of spectrum sensing mismatch (SSM). In this paper, we present the deterministic analysis of TDCS systems under arbitrary given spectrum sensing scenarios, especially the influence of the SSM pattern to the signal to noise ratio (SNR) performance. Simulation results show that arbitrary SSM pattern can lead to inferior bit error rate (BER) performance.

Introduction of a new opto-electrical phase-locked loop in CMOS technology: the PMD-PLL

NASA Astrophysics Data System (ADS)

Ringbeck, Thorsten; Schwarte, Rudolf; Buxbaum, Bernd

1999-12-01

The huge and increasing need of information in the industrial world demands an enormous potential of bandwidth in telecommunication systems. Optical communication provides all participants with the whole spectrum of digital services like videophone, cable TV, video conferencing and online services. Especially fast and low cost opto-electrical receivers are badly needed in order to expand fiber networks to every home (FTTH--fiber to the home or FTTD--fiber to the desk, respectively). This paper proposes a new receiver structure which is designed to receiver optical data which are encoded by code division multiple access techniques (CDMA). For data recovery in such CDMA networks phase locked loops (PLL) are needed, which synchronize the local oscillator with the incoming clock. In optical code division multiple access networks these PLLs could be realized either with an electrical PLL after opto-electrical converting or directly in the optical path with a pure optical PLL.

Data integration: Combined imaging and electrophysiology data in the cloud.

PubMed

Kini, Lohith G; Davis, Kathryn A; Wagenaar, Joost B

2016-01-01

There has been an increasing effort to correlate electrophysiology data with imaging in patients with refractory epilepsy over recent years. IEEG.org provides a free-access, rapidly growing archive of imaging data combined with electrophysiology data and patient metadata. It currently contains over 1200 human and animal datasets, with multiple data modalities associated with each dataset (neuroimaging, EEG, EKG, de-identified clinical and experimental data, etc.). The platform is developed around the concept that scientific data sharing requires a flexible platform that allows sharing of data from multiple file formats. IEEG.org provides high- and low-level access to the data in addition to providing an environment in which domain experts can find, visualize, and analyze data in an intuitive manner. Here, we present a summary of the current infrastructure of the platform, available datasets and goals for the near future. Copyright © 2015 Elsevier Inc. All rights reserved.

Aeronautical audio broadcasting via satellite

NASA Technical Reports Server (NTRS)

Tzeng, Forrest F.

1993-01-01

A system design for aeronautical audio broadcasting, with C-band uplink and L-band downlink, via Inmarsat space segments is presented. Near-transparent-quality compression of 5-kHz bandwidth audio at 20.5 kbit/s is achieved based on a hybrid technique employing linear predictive modeling and transform-domain residual quantization. Concatenated Reed-Solomon/convolutional codes with quadrature phase shift keying are selected for bandwidth and power efficiency. RF bandwidth at 25 kHz per channel, and a decoded bit error rate at 10(exp -6) with E(sub b)/N(sub o) at 3.75 dB are obtained. An interleaver, scrambler, modem synchronization, and frame format were designed, and frequency-division multiple access was selected over code-division multiple access. A link budget computation based on a worst-case scenario indicates sufficient system power margins. Transponder occupancy analysis for 72 audio channels demonstrates ample remaining capacity to accommodate emerging aeronautical services.

Lynx web services for annotations and systems analysis of multi-gene disorders.

PubMed

Sulakhe, Dinanath; Taylor, Andrew; Balasubramanian, Sandhya; Feng, Bo; Xie, Bingqing; Börnigen, Daniela; Dave, Utpal J; Foster, Ian T; Gilliam, T Conrad; Maltsev, Natalia

2014-07-01

Lynx is a web-based integrated systems biology platform that supports annotation and analysis of experimental data and generation of weighted hypotheses on molecular mechanisms contributing to human phenotypes and disorders of interest. Lynx has integrated multiple classes of biomedical data (genomic, proteomic, pathways, phenotypic, toxicogenomic, contextual and others) from various public databases as well as manually curated data from our group and collaborators (LynxKB). Lynx provides tools for gene list enrichment analysis using multiple functional annotations and network-based gene prioritization. Lynx provides access to the integrated database and the analytical tools via REST based Web Services (http://lynx.ci.uchicago.edu/webservices.html). This comprises data retrieval services for specific functional annotations, services to search across the complete LynxKB (powered by Lucene), and services to access the analytical tools built within the Lynx platform. © The Author(s) 2014. Published by Oxford University Press on behalf of Nucleic Acids Research.

System and method for integrating and accessing multiple data sources within a data warehouse architecture

DOEpatents

Musick, Charles R [Castro Valley, CA; Critchlow, Terence [Livermore, CA; Ganesh, Madhaven [San Jose, CA; Slezak, Tom [Livermore, CA; Fidelis, Krzysztof [Brentwood, CA

2006-12-19

A system and method is disclosed for integrating and accessing multiple data sources within a data warehouse architecture. The metadata formed by the present method provide a way to declaratively present domain specific knowledge, obtained by analyzing data sources, in a consistent and useable way. Four types of information are represented by the metadata: abstract concepts, databases, transformations and mappings. A mediator generator automatically generates data management computer code based on the metadata. The resulting code defines a translation library and a mediator class. The translation library provides a data representation for domain specific knowledge represented in a data warehouse, including "get" and "set" methods for attributes that call transformation methods and derive a value of an attribute if it is missing. The mediator class defines methods that take "distinguished" high-level objects as input and traverse their data structures and enter information into the data warehouse.

Joint channel estimation and multi-user detection for multipath fading channels in DS-CDMA systems

NASA Astrophysics Data System (ADS)

Wu, Sau-Hsuan; Kuo, C.-C. Jay

2002-11-01

The technique of joint blind channel estimation and multiple access interference (MAI) suppression for an asynchronous code-division multiple-access (CDMA) system is investigated in this research. To identify and track dispersive time-varying fading channels and to avoid the phase ambiguity that come with the second-order statistic approaches, a sliding-window scheme using the expectation maximization (EM) algorithm is proposed. The complexity of joint channel equalization and symbol detection for all users increases exponentially with system loading and the channel memory. The situation is exacerbated if strong inter-symbol interference (ISI) exists. To reduce the complexity and the number of samples required for channel estimation, a blind multiuser detector is developed. Together with multi-stage interference cancellation using soft outputs provided by this detector, our algorithm can track fading channels with no phase ambiguity even when channel gains attenuate close to zero.

Analysis of OFDMA receiver with carrier frequency offset and common carrier frequency offset (CCFO)

NASA Astrophysics Data System (ADS)

Gauni, Sabitha; Kumar, R.

2013-01-01

The technique of Orthogonal frequency multiplexing (OFDM) is used to mitigate the multipath effects and to achieve better data rate. When these systems are extended to enable multiple access wireless multimedia communications they are more beneficial. The performance of the OFDM systems degrades with frequency offset and phase offset. The OFDM multiple access (OFDMA) technology allots groups of the OFDM subcarriers allocated to different users for transmission. In this paper we study the interference effects of the individual subcarriers with the neighbouring subcarriers which also plays a role in the system degradation is termed as Multiuser Interference (MUI). The effect of Carrier frequency offset (CFO) on these systems is also taken in account. There are conventional CFO compensation methods for OFDMA systems the CFOs are usually compensated by directly eliminating the intercarrier interference (ICI) caused by the residual CFOs for individual users.